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INFN is developing at LASA lab (INFN Milano, Italy) the prototypes of five corrector magnets, from skew quadrupole to dodecapole, which will equip the high-luminosity interaction regions of the High Luminosity-LHC. These magnets are based on a superferric design, which allows a relatively simple, modular, and easy to construct magnet. This activity takes place within the framework of a collaboration agreement between CERN and INFN. The first prototype, a sextupole, has been assembled in early 2016. We present here the results of the cold test, including the training performed at 4.2 K and the qualification at 2.2 K. We report also on the overall experience gained during its construction and test. An important aspect is represented by the analysis of the manufacturing tolerances of the mechanical pieces and the alignment accuracy achieved. These results will serve as a basis for the design of the next magnets, the octupole, and the decapole. Other important results concern the cold performance of the coil-to-coil electrical joints (especially critical in a magnet with a large number of coils), dynamic inductance measurements and quench studies. | CERN and INFN, Italy, have signed an agreement for RD the fringe field analysis; the magnet powering and quench protection; mechanical and construction main choices. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,400 |
Synchronous colorectal cancer with liver metastasis (SCLM) represents a challenge for both surgeons and oncologists once 15-25% of patients diagnosed with colon cancer present metastatic liver disease. Surgical strategies have been developed in order to stratify patients and achieve better outcomes as simultaneous resection and reversal approach. | The idea of mucoadhesive was derived from the requirement to localize medication at a particular site within the body. Extent of drug absorption are often increased by increasing duration of the drug at the absorption site within the GI tract. Since several medication are absorbed solely from the higher a part of the bowel localizing oral drug delivery systems within the abdomen or within the small intestine would considerably improve the extent of drug absorption The idea of mucoadhesive was derived from the requirement to localize medication at a particular site within the body. Extent of drug absorption is often increased by increasing duration of the drug at the absorption site within the GI tract. Since several medication are absorbed solely from the higher a part of the bowel localizing oral drug delivery systems within the abdomen or within the small intestine would considerably improve the extent of drug absorption | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,401 |
In this work, we study in a system with weak axial non-uniformity, the required shape of the beam-tunnel boundary, so that the cross-section of a non-axisymmetric electron beam is preserved, in spite of the E/spl times/B drift. For a beam with elliptic cross section (including the limit of a sheet beam), the Poisson equation has been solved to first order in the non-uniformity, thus defining the suitable shape of the beam tunnel boundary. | The availability of high-power microwave sources like gyrotrons makes it now possible to use the Gaussian output RF beam of a conventional gyrotron propagating in free space as an input for the interaction with a sheet electron beam (e-beam) drifting along an external magnetic field, with the aim of generating even higher RF power. Since this interaction is from the beginning in the nonlinear high-efficiency regime, the corresponding field amplitude is adequate to extract a significant amount of power from the high-current e-beam with no need for feedback from the walls of any cavity or resonator. The radiation field excited by the nonlinear perturbed electron motion has been calculated using a self-consistent iterative scheme and is seen to maintain the basic features of the initial RF beam (such as the Gaussian profile), but at a much higher power level as is desired for a fusion reactor. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,402 |
publisher: Elsevier articletitle: Analytical investigation of hydrodynamic performance of a dual pontoon WEC-type breakwater journaltitle: Applied Ocean Research articlelink: http://dx.doi.org/10.1016/j.apor.2017.03.012 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved. | In the present paper, linear hydroelastic analysis is performed for the assessment of the behavior of a Flexible Floating Breakwater (FFB), which represents not only a structure for shore protection but also a device for wave energy production with the utilization of a linear hydraulic Power Take-Off mechanism (PTO). The linear hydroelastic analysis is conducted in frequency domain with a radiation/diffraction 3D hydrodynamic model considering the effect of the flexibility of the FFB as well as the damping associated with the energy extraction by the PTO mechanism. A framework for this analysis is proposed and demonstrated, which includes three components: (a) a 3D structural model for an initial eigenvalue analysis, (b) a 3D hydrodynamic model for the hydroelastic analysis and (c) a numerical analysis for the calculation of the forces associated with the PTO and, also, for the estimation of the generated power. FFB consists of a grid of flexible floating modules connected flexibly in two directions by: (a) connectors with known properties and (b) hydraulic Power Take-Off mechanisms with known linear damping characteristics. The PTO mechanisms can be oriented in any possible direction in space. The investigation of the FFBs’ behavior is executed for two grids with different number of modules as well as for different combinations of translational and rotational stiffness of the FFB's connectors and different damping coefficients of PTO. The combined effect of wave energy extraction, behavior and a desired level of protection by the FFB is illustrated. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,403 |
The present work aims to analyze the influence of the in-plan distribution of asperities on the contact between periodically rough surfaces. Square pattern and hexagonal pattern rigid surfaces are considered. Their contact with an elastic half-space is analyzed by numerical simulations. Three surfaces are generated with identical asperities periodically distributed in a plan according to different patterns. It follows from numerical results that when the load and the real contact area are small, the asperities act almost independently. However, the interaction between close asperities increases with the load becomes intensified and has a significant effect on the contact area when the situation is close to full contact. | The area and pressure distribution in elastic contacts between frictionless, nonadhesive surfaces is studied as a function of load and surface geometry using finite element calculations. Surfaces that follow self-affine scaling on all resolved scales are compared to surfaces with cutoffs at small and large length scales, and experimental surfaces that are not self-affine. In all cases the true area of contact is proportional to load and inversely proportional to elastic modulus and the mean slope of the surface. The constant of proportionality K is nearly constant and lies between analytic predictions. Large wavelength cutoffs lead to a small increase in K, a homogeneous distribution of contacts at large scales, and limit the size of the largest connected regions. Small wavelength cutoffs lead to local redistributions in pressure that decrease the probability of low and high local pressures. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,404 |
Present work analyzes the flow hydrodynamics and mass transfer mechanisms in double Rushton and CD-6 impeller on wide range (0.0075–0.25 m/s) of superficial gas velocity (v g) in a gas-liquid phase bioreactor by employing computational fluid dynamics (CFD) technique. The volume averaged velocity magnitude and dissipation rate are found higher with increasing superficial gas velocity. Higher relative power draw (P g/P 0) is predicted in CD-6 than the Rushton impeller but no significant difference in volume averaged mass transfer coefficient (k L a) observed between these two types of impeller. The ratio of power draw with mass transfer coefficient has been found higher in CD-6 impeller (25–50 %) than the Rushton impeller. | The paper presents the results of numerical simulations of hydrodynamics in a gas–liquid pseudophase system (sucrose solution with yeast suspension). The simulations were performed in a bioreactor with a working volume of 0.02 m3, equipped with a Rushton turbine or Smith turbine stirrers. The results of the study were developed in the form of vectors of liquid velocity and the contours of the analyzed magnitudes. Also, the local values of the gas hold-up φ in the gas–liquid pseudophase system were presented. The results of numerical simulations of the gas hold-up were compared to the results of my own experimental study. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,405 |
Full Brillouin zone ab-initio band-structure data was computed for a range of different strain configurations. This data was then used as target data set for the calibration of empirical pseudopotential parameters. Energy dependent statistical weights were used to emphasize critical features. The resulting pseudopotential parameterization was validated by comparing the strain dependence of density-of-states data obtained using empirical pseudopotentials to corresponding ab-initio results. Bulk Monte Carlo simulations were performed to study the strain induced mobility response. | The density functional theory (DFT) computation of electronic structure, total energy and other properties of materials, is a field in constant progress. In order to stay at the forefront of knowledge, a DFT software project can benefit enormously from widespread collaboration, if handled properly. Also, modern software engineering concepts can considerably ease its development. The ABINIT project relies upon these ideas: freedom of sources, reliability, portability, and self-documentation are emphasised, in the development of a sophisticated plane-wave pseudopotential code. We describe ABINITv3.0, distributed under the GNU General Public License. The list of ABINITv3.0 capabilities is presented, as well as the different software techniques that have been used until now: PERL scripts and CPP directives treat a unique set of FORTRAN90 source files to generate sequential (or parallel) object code for many different platforms; more than 200 automated tests secure existing capabilities; strict coding rules are followed; the documentation is extensive, including online help files, tutorials, and HTML-formatted sources. (C) 2002 Elsevier Science B.V. All rights reserved. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,406 |
The interaction between a small twist and a horizontal chromospheric shocktube is investigated. The magnetic flux tube is modeled using 1.5-D magnetohydrodynamics. The presence of a supersonic yet sub-Alfvenic flow along the flux tube allows the Alfvenic pulse driven at the photospheric boundary to become trapped and amplified between the stationary shock front and photosphere. The amplification of the twist leads to the formation of slow and fast shocks. The pre-existing stationary shock is destabilized and pushed forward as it merges with the slow shock. The propagating fast shock extracts the kinetic energy of the flow and launches rapid twists of 10–15 km s−1 upon each reflection. A cavity is formed between the slow and fast shocks where the flux tube becomes globally twisted within less than an hour. The resultant highly twisted magnetic flux tube is similar to those prone to kink instabilities, which may be responsible for solar eruptions. The generated torsional flux is calculated. | Preface 1. A description of the Sun 2. Basic equations of MHD 3. Magnetohydrostatics 4. Waves 5. Shock waves 6. Magnetic reconnection 7. Instability 8. Dynamo theory 9. Magnetoconvection and sunspots 10. Heating of the upper atmosphere 11. Prominences 12. Solar flares and coronal mass ejections 13. The solar wind Appendices References Index. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,407 |
The printing quality delivered by a Drop-on-Demand (DoD) inkjet printhead is mainly limited due to the residual oscillations in the ink channel. The maximal jetting frequency of a DoD inkjet printhead can be increased by quickly damping the residual oscillations and by bringing in this way the ink-channel to rest after jetting the ink drop. The inkjet channel model obtained is generally subjected to parametric uncertainty. This paper proposes a robust optimization-based method to design the input actuation waveform for the piezo actuator in order to improve the damping of the residual oscillations in the presence of parametric uncertainties in the ink-channel model. Experimental results are presented to show the efficacy of the proposed method. | A high-speed waveform design method for piezo inkjet printing is proposed. This method uses the pressure wave information inside the ink dispenser. The pressure wave inside the inkjet dispenser can be effectively measured from the piezo current because the piezo has the self-sensing capability. The measured pressure wave was compared with the dispenser vibration measured by the laser Doppler vibrometer. For high-speed inkjet printing, a two-pulse waveform was designed based on the measured pressure wave to effectively suppress the residual pressure wave after jetting. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,408 |
: NOVA code calculations were performed to predict flamespreading and pressure waves in an Army 155mm howitzer full bore charge (155) and the Navy 5 inch, 54 caliber gun (5/54) with a special service charge. A Zeldovich form of a transient burning model replaced the usual quasi-steady pressure dependence of regression rate. Some differences were noted for the Army application; Navy calculations showed a wide difference. Both calculations showed that transient burning can affect an interior ballistics calculation although several refinements are needed before full gun calculations can be performed. | : All current gun interior ballistics computer programs rely on, and are sensitive to, the steady state burning rate 'law', r = ap to the n power. It is not clear that this is a valid representation in a highly transient pressure environment. To estimate possible dynamic effects, numerical solutions for three thermal-wave combustion models (KTSS, Levine/Culick, Kooker/Zinn) are obtained for a series of example cases where the imposed pressure variation at the edge of the flame zone is prescribed by an experimental pressure-time history from the 105mm Gun M68. The results obtained with several different numerical solution methods indicate that (1) at low pressure (early time) the instantaneous propellant burning rate can be much greater than ap to the n power; while at high pressure the burning rate returns asymptotically to ap to the n power, and (2) burning rate 'runaway' is a numerical difficulty and is not a solution to the combustion models. The effect of dynamic burning rate on closed-bomb measurements is estimated numerically with a simple model. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,409 |
Based on theories of lifting integer wavelet,image processing and information hiding,the authors propose an information hiding algorithm with two thresholds,introduce its principle and steps to achieve,and give the specific algorithm and implementation process.It embedded secret information in integer wavelet high frequency subband coefficient using two thresholds.When extracting the embedded data the gray value overflow problem is resolved during wavelet inverse transform,and increased size and security of secret information.It was analyzed the threshold value variation,size of secret data and security with experiment data etc.Experiments show the method can embed secret information in great size.The results show that this method increases the safety and hiding capacity of secret information. | Based on wet paper code, integer wavelet and matrix coding, this paper constructs a new steganographic algorithm. Combine with the advantage in integer wavelet domain, which more close to HVS, a part of secret messages are embedded by LSB in high-frequency coefficients after integer wavelet switch, wet paper code is used to change the direction of embedding. Another part of secret messages are embedded by matrix coding in low-frequency coefficients after integer wavelet switch, wet paper code is still used to change the direction of embedding. The performance of the proposed approach shows that security and capacity of secret messages are improved in integer wavelet domain. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,410 |
Two planar diversity antennas operating in Ku- (12.4-18 GHz) and K-band (18-26.5 GHz) are proposed for ultra-wideband (UWB) applications. Both of them consist of a monopole radiating element and two orthogonal feeding ports. Their ground planes are modified and optimized to improve the isolation as well as to control the radiation. The first one is a pattern diversity antenna with a disc monopole patch. The second one is a polarization diversity antenna based on a square patch which is able to provide both linear and circular polarizations. Different feeding approaches are adopted to obtain a broadband impedance matching. Two wideband couplers are designed to provide the required feeding circuit. Both the simulated and measured results are presented to verify the proposed idea. Good radiation efficiency and isolation between the two ports are achieved. Consistent diversity performance is observed across the whole UWB bandwidth which is demonstrated by their radiation patterns. | Wireless transmission over 15Gb/s data rate is reported using space diversity MIMO. Multi-diversity planar antennas are designed and fabricated to transmit and receive the radio frequency signal simultaneously in 2 radiation diversities. Reliable 15Gb/s indoor data transmission over 5m distance is demonstrated in the super high frequency band (SHF) of 11.6GHz to 20.4GHz. Low BER is achieved with 2×2 MIMO space time block coded OFDM modulation. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,411 |
Roll forming of sheet metal is considered in terms of four fundamental types of deformation: longitudinal stretching, longitudinal bending, transverse bending and shear. Strain and work expressions are developed for each deformation type. Three of the deformation types are associated with simple sectional properties and from these it is possible to predict their relative magnitudes. It is shown that shear strain is potentially far larger than the other deformation types. Some of the implications for practical roll design are discussed. | Roll forming process, due to increased product performance, higher quality, and lower cost with other advantages, has been made suitable process to form any shapes in the sheets. In this paper stress, strain and thickness distribution in the steel galvanized hot coil commercial (SGHC) sheet with Round shape ribs formed by roll forming process was investigated by a Finite Element code, ABAQUS software. The stress and strain distributions are considered during forming. Since in round shape ribs the flow of material is easier than quadrilateral one, the Stress distribution was more uniformand thinning strain was concentrated in the ribs with maximum value of 14.5% while this value in quadrilateral shape rib forming is 15.5%. The results show that this method is applicable in reducing the thickness strain. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,412 |
The transient second harmonic generation and linear optical reflectivity signals measured simultaneously in reflection from GaAs/GaSb/InAs and GaAs/GaSb heterostructures revealed a new mechanism for creating self-induced transparency in narrow bandgap semiconductors at low temperatures, which is based on the dual-frequency electro-optic soliton propagation. This allows the ultrafast carrier dynamics at buried semiconductor heterointerfaces to be studied. | Low-energy collective electronic excitations exhibiting sound-like linear dispersion have been intensively studied both experimentally and theoretically for a long time. However, coherent acoustic plasmon modes appearing in time-domain measurements are rarely observed due to Landau damping by the single-particle continua. Here we report on the observation of coherent acoustic Dirac plasmon (CADP) modes excited in indirectly (electrostatically) opposite-surface coupled films of the topological insulator Bi2Se3. Using transient second-harmonic generation, a technique capable of independently monitoring the in-plane and out-of-plane electron dynamics in the films, the GHz-range oscillations were observed without corresponding oscillations in the transient reflectivity. These oscillations were assigned to the transverse magnetic and transverse electric guided CADP modes induced by the evanescent guided Lamb acoustic waves and remained Landau undamped due to fermion tunnelling between the opposite-surface Dirac states. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,413 |
In previous papers, the authors have reported on the design and implementation of reflective middleware platforms. The aim of this paper is to consider the implications of such an architecture for the area of quality of service (QoS) management. More specifically, the paper describes how critical QoS management functions can be incorporated into our reflective middleware platform, with particular emphasis on the dynamic QoS management functions of QoS monitoring and adaptation. It is argued that the reflective approach leads to a natural and highly flexible implementation of such QoS management functions (and indeed the approach offers considerable benefits over more conventional approaches). | In order to support multimedia applications in mobile environments, it will be necessary for applications to be aware of the underlying network conditions and also to be able to adapt their behaviour and that of the underlying platform. This paper focuses on the role of middleware in supporting such adaptation. In particular, we investigate the role of open implementation and reflection in the design of middleware platforms such as CORBA. The paper initially extends CORBA with the concept of explicit binding, where path of communication between objects is represented as first class objects. We then introduce the concept of open bindings which support inspection and adaptation of the path of communications. An implementation of open bindings is described, based on the Ensemble protocol suite from Cornell University. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,414 |
Deformation of rock samples compressed up to failure has been studied in laboratory. A system of trustworthy deformational precursors of the failure stage has been developed. The system includes long-term, middle-term and short-term precursors, which correspond to the threshold of dilatancy, change of the specific volume deformation, and jump of the specific volume deformation increments, respectively. Proposed methods of the complex research include deformation and mathematical methods. The mathematical model of deformation in samples of rocks at uniaxial compression is founded on hypothesis of self-equilibrium stresses. The model had been successfully used for description of oscillating deformation. Good coincidence between the experimental and theoretical results has been observed. | "If the world is meaningless that prevents invent any sense?"-Lewis Carroll “Alice's Adventures in Wonderland”. About 50 years ago importance to apply differential geometry for extending the elastic continuous medium model was recognized by researchers. The introduced affine-metric objects characterize the internal geometric structure of the continuous media and its difference from the Euclidean geometry. The affine- metric objects are the internal variables, and they can't be measured directly. This book shows how to establish the relation between the non-Euclidean geometric parameters of description and experimentally measured characteristics. It is demonstrated on the basis of the non-equilibrium thermodynamics formalism that to determine the affine-metric characteristics it is experimentally sufficient to measure two independent functions: internal energy and dissipation function. The proposed approach allows us to construct a thermomechanical model of a continuous medium including a full set of non-Euclidean characteristics which corresponds, from the physical point of view, to the description of dislocations, disclinations and point defects. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,415 |
A scanning thermal microscope is used to study the temperature distribution on the gate surface of a MOS structure submitted to an electric stress. Over a threshold of stress current intensity, hot spots have been observed and then numbered versus stress conditions. The data analysis shows that the hot spots number depends on injected current and also on the MOS structure degradation history. The temperature map of the gate surface is riddled with hot spots since the sample breakdown. Otherwise, hot spots seem to appear in privileged areas like the gate borders. On the basis of the literature, our observations lead us to conclude that hot spots result of degradations inside the structure. | We have studied temperature variations on two dissipative structures with two different techniques. The dissipative structures are constituted of thin (0.35µm) dissipative resistors, the distance between two resistors being equal to 0.8 or 10 µm. On one hand, we have used a thermoreflectance imaging technique which is a well-known non contact optical method to evaluate temperature variations but whose spatial resolution is limited by diffraction. On the other hand, we have used a Scanning Thermal Microscope (SThM) to study the thermal behaviour of these small dissipative structures. We compare qualitative results obtained by both methods and we present their advantages and limitations for temperature measurements on microelectronic devices. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,416 |
The development of complex distributed applications running on heterogeneous computer networks raises the strong demand for effective observation and control, i.e., for the management of the entire system behavior. Distributed systems create a new class of requirements especially in the areas of installation, consistent configuration, fault detection, and management exceeding what is necessary for stand-alone applications. In this context more flexibility and generality is required for both the management system and the instrumentation of the application components than that provided by existing network management systems. This paper proposes a method to support the development of manageable distributed applications based on a formal management interface definition and an instrumentation library. This method is also applicable to already existing components of distributed applications provided their source code is available. | The author notes that standard network management has certainly had a great impact on the industry. However, he further points out that it is important to distinguish between two kinds of standards, horizontal and vertical. Horizontal standards, such as management protocols and management objects, can at most provide a technology base for enabling products. However, in order to produce a robust market, vertical standards, such as APIs and a framework for management applications are needed. The author notes that the industry continues its struggle to distinguish between dreams and reality; 'architectures' and marketeers are very good at seducing the industry's attention for long periods of time. Fortunately, it is the engineers who must ultimately deliver products that provide cost-effective solutions. As such, the outcome is uncertain, the author concludes. > | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,417 |
LHC is expected to be a top quark factory. If the fundamental Planck scale is near a TeV, then we also expect the top quarks to be produced from black holes via Hawking radiation. In this Letter we calculate the cross sections for top quark production from black holes at the LHC and compare it with the direct top quark cross section via parton fusion processes at next-to-next-to-leading order (NNLO). We find that the top quark production from black holes can be larger or smaller than the pQCD predictions at NNLO depending upon the Planck mass and black hole mass. Hence the observation of very high rates for massive particle production (top quarks, Higgs or supersymmetry) at the LHC may be an useful signature for black hole production. | We suggest a quantum black hole model that is based on an analogue to hydrogen atoms. A self-regular Schwarzschild-AdS black hole is investigated, where the mass density of the extreme black hole is given by the probability density of the ground state of hydrogen atoms and the mass densities of nonextreme black holes are given by the probability densities of excited states with no angular momenta. Such an analogue is inclined to adopt quantization of black hole horizons. In this way, the total mass of black holes is quantized. Furthermore, the quantum hoop conjecture and the Correspondence Principle are discussed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,418 |
The work is devoted to study of temperature operation of a 150 kV underground cable line with XLPE insulation. The stationary thermal conditions were calculated. The influence of outer boundary radius selection on the temperature distribution was analyzed. The limiting value of the filling mixture thermal conductivity was found, which provides an acceptable temperature of the cable. | Land shortage in metropolitan vicinities entails subsurface implementation of power transmission lines (PTLs) which demand structural flexibility, as well as substantial load bearing capability. Thus, development of a flexible gas insulated transmission line (FGIL) necessitates its strength degradation analysis, regarding the synergistic effect of aging and mechanical loadings. Moreover, correlation of conductor and enclosure dimensions of FGIL apropos field distribution, requires careful consideration regarding their dimensional specifications. In this research, a comprehensive electro-mechanical design is performed for the proposed flexible-thermoplastic-enclosure of a 132 kV FGIL by considering the synergistic impact of time and temperature-based aging, along with the effect of external and internal loadings, such as dead load, live load and internal gas pressure. Additionally, a recursive design algorithm for the proposed scheme regarding electro-mechanical aspects, along with aging perspectives is developed. Comparative analysis of proposed and conventional schemes regarding electro-mechanical and aging aspects revealed that the proposed enclosure exhibits the required structural strength, as well as flexibility for trenchless subsurface application of FGILs in metropolitan areas. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,419 |
SAXS profiles of ionomers often show a typical scattering peak located at q∼1-3 nm -1 due to ionic aggregation and a zero-order scattering upturn. Anomalous SAXS (ASAXS) has confirmed that such an upturn is due to ions. The structure of ionic aggregates and the spatial arrangement of ions can best be elucidated by the correlation function analysis of precise SAXS profiles which have a wide scattering angular range and a high spatial resolution. Electron density-density correlation functions of sulfonated polystyrene sodium and zinc salts (4.5 mol% of sulfur, 100% neutralization and M w /M n = 1.1) were computed from the SAXS profiles | The effect of neutralization level on the dynamic mechanical properties and morphology of partly neutralized poly(ethyl acrylate-co-Na acrylate) EANa ionomers was investigated. The mechanical data of EANa ionomers were compared to those of polystyrene-based ionomers having higher T g but lower ion content than the EANa ionomers. It was found that at ca. 44 % neutralization, compared to ca. 50 % neutralization for styrene ionomers, the ionomers started to show cluster T g and ionic modulus. Thus, it was suggested that the 40–50 % neutralization level might be a starting point, at which the amorphous Na-neutralized ionomers, regardless of the matrix T g and acid content, behaved like bi-phasic materials. The SAXS study suggested that with increasing neutralization level the number of multiplets increased slightly but the number of ion pairs per multiplet increased systematically. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,420 |
The laser-Doppler velocimeter is used to measure the mean and the fluctuating velocity for turbulent flow over a solid sinusoidal wave surface having a wavelength λ of 50.8 mm and a wave amplitude of 5.08 mm. For this flow, a large separated region exists, extending from x /λ = 0.14 to 0.69. From the mean velocity measurements, the time-averaged streamlines and therefore the extent of the separated region are calculated. Three flow elements are identified: the separated region, an attached boundary layer, and a free shear layer formed by the detachment of the boundary layer from the wave surface. The characteristics of these flow elements are discussed in terms of the properties of the mean and fluctuating velocity fields. | An erodible bed sheared by a fluid flow, gas or liquid, is generally unstable, and bed forms grow. This review discusses the following issues, in light of the recent literature: What are the relevant dynamical mechanisms controlling the emergence of bed forms? Do they form by linear instability or nonlinear processes such as pattern coarsening? What determines their timescales and length scales, so different in air and water? What are the similarities and differences between aeolian and subaqueous patterns? What is the influence of the mode of transport: bed load, saltation, or suspension? Can bed forms emerge under any hydrodynamical regime, laminar and turbulent? Guided by these questions, we propose a unified description of bed-form growth and saturation, emphasizing the hydrodynamical regime in the inner layer and the relaxation phenomena associated with particle transport. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,421 |
An increase in shipboard applications of lightweight structures has been evident over the recent years in both military and commercial vessels. Ship panel distortions generated through various stages of production (e.g., material handling, blast and paint, panel fabrication, subassembly, assembly, outfitting, and erection) have emerged as a major obstacle to the cost-effective fabrication of these lightweight structures. This problem is particularly challenging for naval ships that are built with relatively thin plate and require fair surfaces to maximize hydrodynamic performance and minimize radar signature. With a recent major initiative funded by the U.S. Navy, a comprehensive assessment of the lightweight panel fabrication technology has been undertaken. This assessment took into account the residual stresses of thin plate conditions during the material handling, cutting, fitting, and welding processes. A series of test panels with varying degrees of complexity representing the typical shipboard applications were designed and used to quantify dimensional variations through the entire fabrication processes in a production environment. A light detection and ranging (LIDAR) measurement system was used to analyze panel distortion topography resulting from different processes. Welding attributes, stiffener assembly sequence, and material handling methods were systematically monitored and evaluated to identify areas for fabrication improvement. Advanced computational tools were further developed and used to establish the underlying distortion mechanisms and critical process parameters in these panel structures. Some of the major findings include the following: (1) local buckling is the dominant distortion mechanisms in lightweight panel structures; (2) special care must be exercised in material handling of lightweight structures in preventing long-range permanent deformation; (3) dimensional accuracy from thermal cutting can have a significant impact on buckling distortions, particularly for different thickness combinations in complex panels; (4) any effective mitigation techniques for minimizing buckling distortion should either reduce the buckling driving force (fabrication induced stresses) and/or increase the buckling resistance (e.g., panel geometric parameters and assembly procedures); (5) butt welding of plates to make panels requires a low heat input narrow groove process to minimize distortion prior to fillet welding of stiffeners; (6) precision fillet welding process with automatic seam tracking offers the potential to minimize overwelding. | © 2012 Soul and Hamdy, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Numerical Simulation of Residual Stress and Strain Behavior After Temperature Modification | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,422 |
In this paper the classical notion of a controlled invariant subspace, together with its main properties, is extended to the case of linear periodic discrete-time systems, and used for deriving necessary and sufficient solvability conditions for the disturbance-localization problem and a synthesis procedure for the solution. Moreover, the notions of outer and inner controllable subspaces are introduced and studied for the same class of system, thus allowing the derivation of necessary and sufficient solvability conditions for the disturbance-localization problem with output or state dead-beat control and to give synthesis procedures for the solutions. | State covariances of linear systems satisfy certain constraints imposed by the underlying dynamics. These constraints dictate a particular structure of state covariances. However, sample covariances almost always fail to have the required structure. The renewed interest in using state covariances for estimating the power spectra of inputs gives rise to the approximation problem. In this note, the structured covariance least-squares problem is formulated and the Lyapunov-type matricial linear constraint is converted into an equivalent set of trace constraints. Efficient unconstrained maximization methods capable of solving the corresponding dual problem are developed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,423 |
This study evaluates the marginal adaptation of ceramic copings (In-Ceram, Vita) front of two finish lines and internal surface treatment (Rocatec, ESPE). For this, two master steel dies were milled with all-ceramic crowns preparation, one with a round shoulder (RS) margin design, and the other with a deep chamfer (DC). Twenty copings were made, and the marginal discrepancy was evaluated in measuring microscope, obtaining an initial measure. Each group was divided in two others, which received two kinds of silica sandblasting: (1) in all inner crown surface - DCt and RSt - and (2) in the inner crown surface, but preserving the cervical edge - DCa and RSa. The discrepancies were measured again and the data submitted to the statistical analysis. Marginal discrepancy values of 42,37±18,78µm were observed for group DC and 33,35±20,08µm for group RS in the initial measures, without significant statistical differences among them. The initial and final gap values were compared to each one of the experimental groups, being observed statistical differences in DCa and DCt. Statistical differences was not observed among the post-sandblasting values. It was concluded that both cervical endings present similar marginal adaptations between them when not submitted to any treatment type. When accomplished the surface treatment, negative influence was observed in the marginal adaptation of some groups, if compared the initial and final values, in spite of differences among the last ones were not been observed. | Silica coating can improve bonding of resin to glass-infiltrated aluminum oxide ceramic (In-Ceram), and sandblasting is a pretreatment to thermal silica coating (Silicoater MD system) or a tribochemical coating process (Rocatec system). This study evaluated the effects of sandblasting and coating techniques on volume loss, surface morphology, and surface composition of In-Ceram ceramic. Volume loss through sandblasting was 36 times less for In-Ceram ceramic compared with a feldspathic glass ceramic (IPS-Empress), and sandblasting of In-Ceram ceramic did not change its surface composition. After tribochemical coating with the Rocatec system, a layer of small silica particles remained that elevated the silica content to 19.7 weight percentage (energy-dispersive spectroscopy). Ultrasonic cleaning removed loose silica particles from the surface and decreased the silica content to 15.8 weight percentage, which suggested firm attachment of most of the silica layer to the surface. After treatment with the Silicoater MD system, the silica content increased only slightly from that of the sandblasted specimen. The silica layer created by these systems differs greatly in both morphology and thickness, which could result in different bond strengths. Sandblasting of all ceramic clinical restorations with feldspathic glass materials should be avoided, but for In-Ceram ceramic the volume loss was within an acceptable range and similar to that of noble metals. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,424 |
In a multivariate stratified sampling more than one characteristic are defined on every unit of the population. An optimum allocation which is optimum for one characteristic will generally be far from optimum for others. A compromise criterion is needed to work out a usable allocation which is optimum, in some sense, for all the characteristics. When auxiliary information is also available the precision of the estimates of the parameters can be increased by using it. Furthermore, if the travel cost within the strata to approach the units selected in the sample is significant the cost function remains no more linear. In this paper an attempt has been made to obtain a compromise allocation based on minimization of individual coefficients of variation of the estimates of various characteristics, using auxiliary information and a nonlinear cost function with fixed budget. A new compromise criterion is suggested. The problem is formulated as a multiobjective all integer nonlinear programming problem. A solution procedure is also developed using goal programming technique. | We consider the problem of multivariate multi-objective allocation where no or limited information is available within the stratum variance. Results show that a game theoretic approach (based on weighted goal programming) can be applied to sample size allocation problems. We use simulation technique to determine payoff matrix and to solve a minimax game. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,425 |
Whole-plant drought tolerance and leaf abscission in response to drought of 5-month-old, half-sib black walnut (Juglansnigra L.) seedlings representing seven geographic origins were examined. Seedlings were subjected to six different levels of drought stress and then reirrigated. Mortality, leaf abscission, and refoliation responses were measured. Only one of 404 seedlings actually died. Survival of stem cambial tissues at predawn leaf xylem pressure potential values as low as −4.0 MPa was associated with the capacity for drought-induced leaf abscission. The percentage of seedlings exhibiting at least 80% leaf abscission increased linearly as predawn leaf xylem pressure potential decreased from −1.5 to −3.5 MPa. Although substantial differences in leaf abscission among families were observed, these differences were not statistically significant (P ≤ 0.05). Eighteen percent of all seedlings exhibited some degree of refoliation upon recovery of plant water status. However, the cumulative area of regrowth fo... | • Context ::: Walnuts (Juglans spp.) are ecologically and commercially important trees, yet synthesis of past and current research findings on walnut ecophysiology is lacking, especially in terms of potential acclimation to climate change. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,426 |
Magnetic data are often recorded in text files by magnetometers. They are not easy to deal with, and they are often transferred and written into Excel files to further process. The aim of this paper is to discuss how to use Visual C# to do the transferring work. Development tools, key technologies and flow chart of the program edited by Visual C# are introduced. The main steps of transferring work are elaborated. | In today’s world large number of companies are facing problem related to version control systems. The problem is about comparing binary files such as excel file and recalling what changes have been done over the period of time. It is hard to keep track of what all changes have been made over a set of files in the company and hence comes the need of an approach which can fetch and compare the files with changes that have been done. Since binary files are not readable with human eye, this approach can convert those binary files to XML and compare it on the GUI to show and highlight the changes that have been made over the version control system. A VCS is a system that keeps track of changes one does over a set of files over the time and records it so it can be recalled in the future when needed. Binary file conversion approach is implemented to provide a solution to the problem for the companies that have extensive use for the binary files like Excel and need to refer the changes that were made on them. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,427 |
The time calibration for barrel TOF system of BESIII is studied in this paper. The time resolution for single layer and double layer have been achieved about 97 ps and 78 ps for electrons in Bhabha events respectively. The pulse height correction using electronic scan curve and the predicted time calculated using Kalman filter method are introduced. This paper also describes the analysis of correlation of measured time. | An upgrade, based on Multigap Resistive Plate Chamber (MRPC) technology, of the endcap Time-Of-Flight (ETOF) detector of the Beijing Spectrometer III (BESIII) has been proposed for the replacement of the current scintillator + PMT based ETOF, with the aim of improving the time resolution down to 80 ps sigma. This improvement will enhance the particle identification capability to meet the higher precision requirements of physics. The ETOF system including MRPC modules, Front End Electronics (FEE), CLOCK module, fast control boards and Time to Digital modules (TDIG), has been designed, constructed and parts of the ETOF system have seperately tested. Aiming at examining the quality of entire ETOF system and training the operation of all participated instruments, a cosmic ray test system was built and tested in the laboratory for about three months to guarantee the performance. In this paper the results of the test are presented indicating that the entire ETOF system works well and satisfies the requirements of the upgrade. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,428 |
High-pressure behaviors of wurtzite-type hexagonal CoO nanocrystals were investigated by in situ high-pressure synchrotron radiation X-ray diffraction measurements up to 57.4 GPa at ambient temperature. It is found that bulk modulus of the hexagonal CoO phase is about 115 GPa at zero pressure. During compression, the hexagonal CoO phase transfers into rocksalt-type cubic phase in the pressure range of 0.8−6.9 GPa. The volume collapse accompanied by the transition was estimated to be about 20%. This is irreversibly phase transformation; that is, the cubic CoO phase remains after pressure release. Based on the data of peak width vs pressure, a cubic-to-rhombohedral phase transition was detected for the nanocrystalline cubic CoO phase with the transition pressure of about 36 GPa, lower than 43 GPa for bulk cubic CoO phase. The bulk modulus of the nanocrystalline cubic CoO phase of about 258 GPa is larger than 180 GPa for the corresponding bulk cubic CoO phase. | We synthesized Cu3.8Ni/CoO and Cu3.8Ni/MnO nanoparticles via an easy and scalable solution synthesis. The synthesized Cu3.8Ni/CoO and Cu3.8Ni/MnO nanoparticles were annealed to remove the organic surfactants without phase transitions or side reactions. Electrons can be transferred via metallic Cu3.8Ni, which will not react with lithium ions. The heterogeneous structures of Cu3.8Ni/CoO and Cu3.8Ni/MnO nanoparticles could enhance the lithium ion mobility and improve the life cycle, and these materials are therefore promising candidates as high-power-density and high-energy-density anode materials for lithium-ion batteries in diverse applications, such as electrical vehicles. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,429 |
We update the well-known BLNY fit to the low transverse momentum Drell-Yan lepton pair productions in hadronic collisions, by considering the constraints from the semi-inclusive hadron production in deep inelastic scattering (SIDIS) from HERMES and COMPASS experiments. We follow the Collins-Soper-Sterman (CSS) formalism with the b_*-prescription. A universal non-perturbative form factor associated with the transverse momentum dependent quark distributions is found in the analysis with a new functional form different from that of BLNY. This releases the tension between the BLNY fit to the Drell-Yan data with the SIDIS data from HERMES/COMPASS in the CSS resummation formalism. | We present the extraction of unpolarized quark transverse momentum dependent parton distribution functions (TMDPDFs) and the non-perturbative part of TMD evolution kernel from the global analysis of Drell-Yan and Z-boson production data. The analysis is performed at the next-to-next-to-leading order (NNLO) in perturbative QCD, using the -prescription. The estimation of the error-propagation from the experimental uncertainties to non-perturbative function is made by the replica method. The importance of the inclusion of the precise LHC data and its influence on the determination of non-perturbative functions is discussed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,430 |
A novel class of dispersants for colloidal processing of Si 3 N 4 in non-aqueous media has been developed. The sedimentation, rheology and adsorption studies show that with O -(2-aminopropyl)- O ′-(2-methoxyethyl)polypropylene glycol (AMPG) as dispersant a deagglomerated stable Si 3 N 4 suspension with low viscosity and high solid volume fraction ( φ >0.5) can be realised. The dispersing ability of AMPG is believed being related to its high affinity of the amino head group to the powder surface and the solubility of the polymer chain. | Bulk graphite blocks are infiltrated by a Si slurry method to form composites of graphite containing SiC or Si3N4 reinforcements, in order to enhance the wear resistance of the graphitic structure. The microstructure of the SiC reinforcements includes nuclei grains and whiskers, while the microstructure of the Si3N4 reinforcements is a mixture of fine grains, grains of blade- and needle-like morphology. The wear rate of the SiC- and Si3N4-reinforced graphitic block is 77.7 and 42.8 μm3/Nmm, respectively, as measured using an unlubricated pin-on-disc test. These values are ˜55% and 75% lower than the wear rate of the reference graphite (174 μm3/Nmm). The coefficient of friction of the composites is as low as the coefficient of friction of the reinforcement-free graphite, showing values of ˜0.17. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,431 |
This paper addresses the question of how to predict the series feedback termination required to generate negative resistance in a microwave transistor in different circuit configurations. Although this question is usually approached through computer modelling and simulation, we present here a simple closed form equation that predicts the value of feedback reactance most likely to generate negative resistance at the input of a 2-port sub-circuit comprising a transistor plus series feedback, based solely on the 2-port S-parameters of the transistor. This simple equation provides new insight into the effect of series feedback on a transistor and leads us to propose a general rule, namely that the series feedback reactance required to generate negative resistance in a given transistor in a given configuration depends on the sign of the imaginary part of the sum of the 2-port S-parameters for the device in that configuration. | Limits of active device S-parameters obtainable using feedback are predicted by classification of feedback mappings. Reverse mapping is used to determine optimum feedback terminations. The prediction of maximum S-parameters and optimal terminations based solely on the measured two-port parameters of the active device is described. The advantage of using the technique is illustrated by an oscillator design example. > | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,432 |
Porous Ti compacts with large size and complex shape for biomedical applications were fabricated in the porosity range from 40.5% to 53.8% by controlling gelcasting parameters and sintering conditions. The experimental results show that the total porosity and open porosity of porous titanium compacts gelcast from the Ti slurry with 34 vol.% solid loading and sintered at 1100°C for 1.5 h are 46.5% and 40.7%, respectively, and the mechanical properties are as follows: compressive strength 158.6 MPa and Young's modulus 8.5 GPa, which are similar to those of human cortical bone and appropriate for implanting purpose. | The porous titanium alloy prepared by gel-casting methods was used as precursor and the composite coatings with hydroxyapatite HA/TiO2 were prepared on the precursor which was treated by NaOH solution, H2O2 + NH3 solution, HF+HNO3, PdCl2 solution to improve the capability of coatings. The microstructure was examined by SEM and the corrosion behavior of the coating layers in the simulated body fluids (SBF) was evaluated by potentiodynamic polarization test and impedance plots. The results show that the corrosion resistance of samples using PdCl2 treatment is superior to else others. The PdCl2 processing provides the substrate surface an excellent oxide film, which plays a key role in the corrosion resistance of coating. The thickness of the coatings is about 60μm and the surface morphologies are more uniform than the others and have no crack. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,433 |
The Smith predictor is the most effective control scheme for processes with dead time while the proportional−integral−derivative (PID) controller is the most widely used controller in industry. This paper presents a control scheme which combines their advantages. The proposed controller is inherently a PID-type controller in which the integral action is implemented using a delay unit rather than a pure integrator while retaining the advantage of the Smith predictor (Smith principle). The setpoint response and the disturbance response are decoupled from each other and can be designed separately. Another advantage of this control scheme is that the robustness is easy to analyze and can be guaranteed explicitly, compromising between the robustness and the disturbance response. Examples show that this controller is very effective in the control of processes with dead time. | Simple formulae are derived to tune/design the PI and PID controllers to meet user-specified gain margin and phase margin. These formulae are particularly useful in the context of adaptive control and auto-tuning, where the controller parameters have to be calculated on-line. The results in this paper can be used to predict the achievable rise time of the closed-loop system, which is useful for self-diagnosis—a desirable feature of ‘intelligent’ controllers. New insights into the internal model control design for the PID controller are also given. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,434 |
High-frequency 3-D ultrasound imaging is an informative tool for diagnosis, surgery planning and skin lesion examination. The purpose of this article was to describe a semi-automated segmentation tool providing easy access to the extent, shape and volume of a lesion. We propose an adaptive log-likelihood level-set segmentation procedure using non-parametric estimates of the intensity distribution. The algorithm has a single parameter to control the smoothness of the contour, and we describe how a fixed value yields satisfactory segmentation results with an average Dice coefficient of D = 0.76. The algorithm is implemented on a grid, which increases the speed by a factor of 100 compared with a standard pixelwise segmentation. We compare the method with parametric methods making the hypothesis of Rayleigh or Nakagami distributed signals, and illustrate that our method has greater robustness with similar computational speed. Benchmarks are made on realistic synthetic ultrasound images and a data set of nine clinical 3-D images acquired with a 50-MHz imaging system. The proposed algorithm is suitable for use in a clinical context as a post-processing tool. | In the field of high-frequency ultrasound imaging ( MHz), tools for characterizing the performance of imaging systems are lacking. Indeed, commercial phantoms are often inadequate for this frequency range. The development of homemade phantoms on the laboratory scale is often required but is hindered by the difficulty in making very small structures that must be distributed with high accuracy in 3-D space. We propose investigating the use of 3-D photopolymer printing to create resolution and calibration phantoms designed for high-frequency ultrasound imaging. The quality and importance of these phantoms are discussed from the point of view of ultrasound parameters and imaging. First, the compressional wave group velocity, acoustic impedance, and attenuation of six photopolymerized materials were measured using temporal and spectral methods in a substitution experimental setup. Measurements were performed on printed samples using a broadband-focused single-element transducer covering a large frequency range (15-55 MHz). Two 3-D phantoms incorporating different shapes and dimensions were designed and printed. Finally, 3-D acoustic images were obtained using either a mechanically driven single-element transducer or a high-frequency commercial imaging system. Three-dimensional printing enabled us to generate phantoms suitable for high-frequency imaging with complex geometry inclusions and with a surrounding material having acoustic properties close to those of human skin. The calculated SNR between the inclusion and surrounding media is approximately 50 dB. In conclusion, 3-D printing is a useful tool for directly, easily, and rapidly manufacturing ultrasound phantoms for ultrasound imaging system assessments and computational calibration or validation. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,435 |
The aim of the present work is to find out whether or not, and to what extent, the environmental impacts of reverse osmosis desalination are reduced when brackish groundwater is used instead of sea water. In order to answer this question, the Life-Cycle Assessment (LCA) methodology is used, and two water production plants are compared. The brackish groundwater scenario is based on a plant located in Almeria (southern Spain), while the sea water scenario is based on literature data. Four impact categories and two environmental indicators, one of them related to brine discharge, are included. The results show that the key life-cycle issue of brackish groundwater desalination is electricity consumption, and since this is substantially reduced with regard to using sea water, the life-cycle impacts are found to be almost 50% lower. An uncertainty analysis based on Monte-Carlo simulation shows that these environmental savings are significant for all impact categories. Potential local impacts provoked by brine discharge are also found to be lower, due to a reduced content of salts. It is concluded that, when and wherever possible, exploitation of brackish groundwater resources should be assigned priority to sea water resources as an input for reverse osmosis desalination, although it must be taken into account that groundwater, as opposed to sea water, is a limited resource. | This work has been financially supported by projects CTQ2008-0690, ENE2010-15585 and CTM2011-23912 (co-financed by ERDF Funds). | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,436 |
Modeling the ore grinding and classification process is very important to the optimization of production index.A hybrid intelligent model is thus developed for the simulation of ore grinding and classification process according to its compositive complexity including nonlinearity,multivariable,time-varying parameters and boundary condition fluctuation.This dynamic model is based on the population balance models for ball mill and sump,TSK(Takagi-Sugeno-Kang) model for net mill power draft,empirical cyclone model together with the RBF networks to compensate for the estimation error of overflow density and particle size distribution.With the actual process data from a grinding circuit of a concentration plant,the simulation results of this hybrid intelligent model have the same dynamic characteristics during the variation in fresh slurry feed velocity,density,particle size distribution and cyclone feed manipulating variables. | The grinding industrial production system is a typical complex nonlinear multivariable process with strongly coupling and large time delays. The up-to-the-minute research results of integrated modeling and intelligent control of grinding process are summarized. It mainly includes the fuzzy control, artificial neural network control, soft-sensor modeling and hybrid intelligent control strategy. In the end the future research directions in the grinding process control field is concluded. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,437 |
A least-squares mixed finite element method for the incremental formulation of elasto-plasticity using a plastic flow rule of von Mises type with isotropic hardening is presented. This approach is based on the use of the stress tensor, in addition to the displacement field, as independent process variables. The nonlinear least-squares functional is shown to constitute an a posteriori error estimator on which an adaptive refinement strategy may be based. For the finite element implementation under plane strain conditions, quadratic (i.e., next-to-lowest-order) Raviart-Thomas elements are used for the stress approximation, while the displacement is represented by standard quadratic conforming elements. Computational results for a benchmark problem of elasto-plasticity under plane strain conditions are presented in order to illustrate the effectiveness of the least-squares approach. | We propose a goal-oriented, local a posteriori error estimator for H(div) least-squares (LS) finite element methods. Our main interest is to develop an a posteriori error estimator for the flux approximation in a preassigned region of interest $D \subset \Omega$. The estimator is obtained from the LS functional by scaling residuals with proper weight coefficients. The weight coefficients are given in terms of local mesh size $h_T$ and a function $\omega_D$ depending on the distance to $D$. This new error estimator measures the pollution effect from the outside region of $D$ and provides a basis for local refinement in order to efficiently approximate the solution in $D$. Numerical experiments show superior performances of our goal-oriented a posteriori estimators over the standard LS functional and global error estimators. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,438 |
Current subcritical limits for a number of uranium and plutonium materials (metals and compounds) as given in the ANSI/ANS standards for criticality safety are based on evaluations performed in the late 1970s and early 1980s. This paper presents the results of an analytical study of the minimum critical mass values for a set of materials using current codes and standard cross section sets. This work is meant to produce a consistent set of minimum critical mass values that can form the basis for adding new materials to the single-parameter tables in ANSI/ANS-8.1. Minimum critical mass results are presented for bare and water reflected full-density spheres and for full density moist (1.5 wt-% water) as calculated with KENO-Va, MCNP4A and ONEDANT. Calculations were also performed for both dry and moist materials at one-half density. Some KENO calculations were repeated using several cross section sets to examine potential bias differences. The results of the calculations were compared to the currently accepted subcritical limits. The calculated minimum critical mass values are reasonably consistent for the three codes, and differences most likely reflect differences in the cross section sets. The results are also consistent with values given in ANSI/ANS-8.1. 3 refs., 2 tabs. | As a contribution to a required review of American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors, limits for plutonium systems have been recalculated to confirm their subcriticality under the stated conditions or to propose other values. This paper presents calculation methods and results. The validity of each calculation method was established by extensive correlation with critical experiments, and in some cases with experiments performed subsequent to the original limit calculations. 48 refs. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,439 |
We report gain-saturated operation of a 13.2 nm table-top laser in Ni-like Cd at a 5 Hz repetition rate. A gain-length product G x L = 17.6 was obtained by heating a precreated plasma with 8 ps duration Ti:sapphire laser pulses with an energy of only 1 J impinging at a grazing angle of 23 degrees. With an average power of approximately 1 muW [corrected] this laser is an attractive coherent source for at-wavelength metrology of extreme UV lithography optics and other applications. | We have recently demonstrated high repetition rate tabletop lasers operating at wavelengths as short as 10.9 nm ::: based on collisional transient excitation of ions in plasmas created by laser heating of solid targets. As a further step in ::: the development of these lasers into very high brightness and fully coherent soft x-ray sources, we have demonstrated ::: injection seeding of the amplifiers with high harmonic seed pulses. We report results of an experiment in which a 32.6 ::: nm Ne-like Ti amplifier was used to amplify a seed pulse from the 25 th harmonic of Ti:Sapphire into the gain saturation ::: regime. Simultaneous amplification of the 27 th harmonic at 30.1 nm was also observed. The seeded soft x-ray laser beam ::: was measured to approach full spatial coherence. We have demonstrated that this scheme is scalable to shorter ::: wavelengths and that is capable of producing extremely bright soft x-ray laser pulse with essentially full coherence. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,440 |
This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso-and microscale systems. Despite the advantages of shape memory alloys-high strain, silent operation, and mechanical simplicity-their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180 degrees motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin (<1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. | The static and dynamic performance of a new kind of linear microactuators of 4/spl times/4/spl times/0.1 mm/sup 3/ size is presented providing large work outputs. The actuators consist of a stress-optimised active microdevice of a shape memory alloy with one-way effect. As a biasing mechanism, a superelastic microspring or a second active device with opposite actuation direction are used. For a maximum strain of 1.3%, strokes above 500 /spl mu/m and maximum forces of 110 mN are achieved. Time-resolved experiments with an optical transmission scheme reveal for a driving power of 190 mW heating and cooling times of 300 ms and 1.5 s, respectively. Considerably shorter switching times are achieved by making use of partial phase transformations. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,441 |
This paper intends to examine the motivation of diversification. We choose the Shanghai listed companies that adopted a diversification strategy in 2011 but realized a declined performance in 2012 as the study samples, and come to the following conclusions: (1) The macro environment will affect the implementation of the diversification strategy for some industries, such as extractive industry, wood furniture industry, rubber industry, and the building industry; (2) As to the sample of downward performance diversified companies, the shareholders’ benefits transfer motivation is an important consideration. Further analysis shows that there are some differences in the degree of diversification, benefits transfer motivation, and the degree of income impairment when the sample is classified by corporate nature, growth stage, and firm size. The differences are more obvious in different corporate natures; and (3) A clear correlation between the management ability and the degree of income impairment is not found. But there are some correlations between ownership concentration and the degree of income impairment. | We investigate the idea that firms diversify to utilize excess capacity of resources. Knowledge of these resources allows us to make predictions about the direction of a firm's expansion. We expect... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,442 |
: A quantitative study was made of the heat budget of the Arctic and its relationship to the atmospheric circulation of the hemisphere. It combines the available data to produce a description of the input, transformation, and output of thermal energy in the Arctic regions and provides new insights into the mechanism of the Arctic climate. The Report points out the specific measurements most urgently needed for future Arctic investigation, if we are not only to explain some of the climatic variations of the past but also to determine how the climate of the future might be foreseen and influenced. | Since the Apr 1957 occupation of the first long-term US drifting station on sea ice, much has been learned about the properties of sea ice as a material. Properties of large, composite sheets of natural sea ice are still to be defined, however, because of the need for accurate knowledge of strength, roughness and albedo, among other parameters. In explanation of the ice cover, studies have been made of energy fluxes, radiative fluxes, albedos, wind and water flow profiles in boundary layers, air and ice temperature profiles and evaporation of condensation. There remain unresolved and complex questions concerning the circumstances under which the present ice cover could change. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,443 |
The sounding rocket for the DELTA (Dynamics and Energetics of the Lower Thermosphere in Aurora) campaign was successfully launched from Andoya at 00:33 UT on Dec 13, 2004. Though it was cloudy at the time of launch, theWeber Na lidar was operating intermittently between 20:00 UT and 23:30 UT on Dec 12, observing Na density, temperature and meridional wind between 80 and 100 km. Throughout the lidar observations, we observed significant small (λz < 5 km) and medium-scale (λz ≈8–15 km) wave activity producing significant wind and temperature shears. There were unusually large (up to 10 m/s and 10 K amplitudes) perturbations of the vertical wind and temperature profiles at 21 UT with a 3 km vertical wavelength that was much stronger in the vertical beam than in the north beam. The atmosphere appeared to become more active as the launch time approached. During the last interval with data, at ∼23:20 UT, Dec. 12th, the lidar profiles revealed a gravity wave in both beams with a magnitude of 5–10 K in temperature and approximately 5 km vertical wavelength. The large background shear plus the wave perturbation produced regions with potential convective instability at multiple altitudes. | This paper describes a laboratory study into the chemical pathways by which Na + is converted to Na in the upper atmosphere. The termolecular clustering reactions of Na + with N 2 , O 2 , and CO 2 were studied in a low-temperature fast flow reactor coupled to a quadrupole mass spectrometer. This yielded κ(Na + + N 2 + He, 93-255 K) = (1.20 ± 0.13) x 10 -30 (T/200 K) -(2.20±0.09) , κ(Na + + O 2 + He, 93-130 K) = (5.20 ± 2.62) x 10-31 (T/200 K) -(2.64±0.74) κ(Na + + CO 2 + He, 158-300 K) = (9.05±1.38) x 10 -30 (T/200 K) -(2.84±0.48) , where the units are cm 6 molecule -2 s -1 and the stated errors are a combination of the 2σ standard errors in the kinetic data and the systematic errors in the temperature, pressure, and flow rates. It was then shown that atomic O will ligand switch with Na.N 2 + but not with Na.CO 2 + , and that the former reaction proceeds essentially at the Langevin collision frequency. The neutralization of Na + in the upper atmosphere is therefore rather complex. The first step is formation of the Na.N 2 + ion from the recombination of Na + with N 2 . This cluster ion can then either switch with CO 2 , which leads to a stable cluster ion that will undergo dissociative electron recombination to form Na; or switch with atomic O, which reforms Na + . The result of this is that the lifetime of Na + changes very rapidly from more than a day above 100 km to just a few minutes at 90 km. Furthermore, the rate of neutralization is largely independent of the electron concentration. A simple model describing the conversion of Na + to atomic Na in a descending sporadic E layer demonstrates that this ion-molecule mechanism appears to fulfil many of the major criteria for producing sporadic sodium layers. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,444 |
Considering the interplay between different phases of fault tolerance, a new problem of locating a faulty module in a computing system is formulated and solved. First, the probability of each module being faulty, or faulty probability, is calculated using the likelihood principle from the model parameters for fault detection, diagnostics, error propagation, and error detection. Then, based on the faulty probabilities and a given required diagnostic coverage, the order in which modules are to be diagnosed and the maximum time allotted to diagnose each module are determined by minimizing the average total diagnostic time. An example is presented and analyzed to answer the question of whether or not a system should delay the diagnosis upon detection of an error until more errors are detected. > | A comparison method for diagnosis of multiprocessor systems is introduced. Given a system of n units modeled by a linear graph, problems of finding the minimum number of comparison edges required for fault detection and fault location are solved by the use of a covering algorithm. The bounds for the number of comparison edges, the number of necessary comparisons and test cycles in fault detection and fault location in systems with n units are determined and an algorithm for an optimal comparison connection assignment is given. Simplicity and ease of implementation make the described method applicable for fault detection and location in multiprocessor systems. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,445 |
The electrostatic forces on an isolated particulate in a low‐pressure discharge are calculated assuming a screened Coulomb potential profile for the particle sheath. In the absence of particle sheath distortion due to a flowing plasma and assuming that there is no charge ‘‘bound’’ to the particle in the form of ions in trapped orbits, the monopolar and dipolar forces on the particle are essentially identical to the corresponding forces on a charged sphere in vacuum. | We report our results on a radio-frequency plasma reactor used for thin-film deposition on particles. Deposition experiments in a reactive dusty plasma seeded with a bimodal distribution of seeds reveal that the mean film thickness is proportional to the deposition time. However, the deposition rate is not uniform for all particles. The distribution of deposition rates is obtained from measurements of the size distribution of the deposited films. The results show that the deposition rate exhibits a wide, approximately exponential distribution, which is attributed to spatial nonuniformities and gradients in the space between the electrodes. The conformity of the deposited films onto the surface of spherical seed particles is studied as a function of time. We find that the sphericity of the deposited film is generally good although deposition on the smallest seeds of this study (0.115 /spl mu/m in radius) show a higher incidence of nonspherical coatings. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,446 |
The use of laser Doppler velocimeters in the analysis of in-plane motion of a solid body is spreading both in the scientific research and in the industrial experimentation fields. The applicability and accuracy of this measurement technique depend on the conditions in which the system operates: the level of the signal available, the characteristics of the surface observed, the environmental conditions, the presence of other shifts in addition to the ones pointed out, etc. This is the subject of this analysis carried out through a comparison between an axial vibrometer in conditions of ideal operation and a tangential vibrometer operating on various surface states. The experimental results have been supported by a theoretic modelling of the interaction between this measuring system and the measurand, thereby providing a rational description of the phenomena observed. This study has made it possible to verify the interfering inputs due to the various operative conditions and the chance of extending the use of the measurement system also to cases in which the applications of the technique proves to be difficult. | Gas-solid two-phase flow is widely used in the industrial process. It is important to know the parameters for the control of process. There are three ways to measure the velocity of the flow but the cross-correlation method and spatial filtering menthod are commonly used in the velocity measurements, so this article summarizes the fundamental principles of the two methods and their advantages and disadvantages. Also the future developments of the velocity measurements are included. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,447 |
In this study, the oscillation behavior and aseismicity of a 4-span Rahmen bridge with a sliding type seismic isolation foundation are investigated using model vibration experiments and numerical simulation. Built on Type III ground, the bridge is erected to 1/10 scale with a sliding-type foundation that was made by separating the footing in the horizontal direction, whereas conventionally piers and foundation structures are rigidly linked together. Teflon (PTFE) was inserted between the separated sections as the sliding interface material. The study results show that a sliding-type seismic isolation foundation has a significant positive effect in decreasing responses during earthquakes and the experimental results can be explained by the dynamic analysis. | During the Chilean earthquakes of May, 1960, a number of tall, slender structures survived the ground shaking whereas more stable appearing structures were severely damaged. An analysis is made of the rocking motion of structures of inverted pendulum type. It is shown that there is a scale effect which makes tall slender structures more stable against overturning than might have been expected, and, therefore, the survival of such structures during earthquakes is not surprising. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,448 |
Guarded Au/n‐GaAs Schottky barrier diodes fabricated from epitaxial and bulk material with carrier concentrations of 2.2×1016 and 7.8×1016 cm−3, respectively, were exposed to fast neutron fluences between 3.6×1014 and 2.2×1015 neutron/cm2. The forward I‐V and 1‐MHz C‐V characteristics remained relatively unchanged after irradiation at the lower fluences where carrier compensation is small (reduction in carrier concentration less than 15%). However, the reverse current increased by more than one order of magnitude at room temperature, which is neither a result of surface leakage (prevented by the guarded device structure used), classical generation‐recombination current (depletion volume changes are too small), nor thermionic emission (too weak a temperature dependence). This increase in reverse current is attributed to enhanced field emission from traps. | Guarded Al-and Au-nGaAs Schottky barrier diodes were subjected to Co60 ?-ray irradiation and their electrical characteristics evaluated. These GaAs Schottkys did not exhibit significant change in their I-V and C-V characteristics up to an absorbed dose as high as 1.5 × 107 rads. Diodes that were previously neutron-irradiated with consequent degradation were also subjected to Co60 irradiation, but no synergistic changes were observed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,449 |
The aim of this paper is to present a detailed analysis of the problem of steady conjugate mixed-convection flow along a vertical finite flat plate which is embedded in a porous medium under the boundary-layer approximation. The problem then reduces to a parabolic partial differential equation which involves only the buoyancy parameter, λ. The cases of both aiding (λ > 0) and opposing (λ | This paper reports us the surface temperature distribution effects of free convective flow along a vertical flat plate with temperature dependent thermal conductivity and viscous dissipation with asymptotic solution. The governing equations with associated boundary conditions reduce to local non-similarity boundary layer equations for this phenomenon are converted to dimensionless forms using a suitable transformation. The transformed non-linear equations are then solved using the implicit finite difference method together with Keller-box technique. Numerical results of the velocity and temperature profiles, skin friction and surface temperature profiles for different values of the thermal conductivity variation parameter, the Prandtl number and the viscous dissipation parameters are presented graphically. Also we considered the asymptotic solution for the effect of the thermal conductivity variation parameter, the Prandtl number and the viscous dissipation parameters in skin friction and surface temperature profiles. Detailed discussion is given for the aforementioned parameters. A good similarity is found in small and large value solution with all value solution for the thermal conductivity variation parameter, the Prandtl number and the viscous dissipation parameter for skin friction and surface temperature. Divergence is found near one (1). GANIT J. Bangladesh Math. Soc. Vol. 36 (2016) 33-46 | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,450 |
A full RCS (radar cross section) calibration technique using a dihedral corner reflector is presented. This method differs from several previous studies in the following aspects: (1) the frequency responses of four measurement channels can be mutually independent and thus no special care has to be taken for signal paths; (2) only scattering matrix measurements of the dihedral at two orientations about the line-of-sight direction are needed since the transmitter and receiver are related through the reciprocity theorem; and (3) simple and useful expressions are used to solve for the calibration parameters. The proposed calibration technique was evaluated by calibrating the cross-polarized return of a sphere, which should be zero. Time domain responses illustrate about a 10-dB overall improvement by using the full calibration procedure. > | A polarimetric radar calibration procedure is introduced and verified with experimental results. The procedure requires measurements of three known targets in order to determine the distortion matrices that characterize the effect of the measurement system on the transmitted and received waves. The scattering matrices for the known targets can be of any form, provided that a limited set of constraints is satisfied. A special case, wherein the transmit and receive distortion matrices are the transpose of each other, is considered. This case is useful for some single antenna systems and has the advantage that only two known targets are required. > | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,451 |
Laminar diffusion flames in counterfiow configurations such as stagnation-point boundary layers are analyzed by methods of matched asymptotic expansions with large parameters being the temperature sensitivities of the rates of chemical heat generation and radiant heat loss. Formulas are derived defining critical conditions for flame extinction, including influences of radiant loss. | A new analytical model of a quasi one-dimensional non-adiabatic dust flame is developed with the assumption that the particle burning rate in the flame front is controlled by the process of oxygen diffusion. In this model, the flame propagation mechanism is considered to be radiation, conduction, and convection. Algebraic equations defining the laminar flame speed were obtained in two limiting cases: lean and rich mixtures. The flame structure is assumed to consist of a preheat zone, a reaction zone, and a postflame zone for lean mixtures and a preheat zone and a reaction zone for rich mixtures. Under the lean mixture approximation, values of the flame speed, lean limit, and flame temperature were calculated by adding the radiation term; flame temperature in the preheat zone increased, while it decreased in the postflame zone. This phenomenon may be attributed to the radiative heat transfer from the postflame zone to the preheat zone. Also, when the radiation term was considered, the flame speed i... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,452 |
This article documents the author’s personal journey as a new evaluator traversing paradigms, continents, and timelines on a quest to discover how best to practice evaluation for the benefit of Maori people (indigenous to New Zealand). The journey has taken the author to a number of evaluation conferences in Australasia and North America, which she has used as monitoring tools to help assess both her progress and the progress of indigenous evaluation generally. The article reports on the positioning of the indigenous evaluation journey from the global perspective afforded by attendance at these conferences. As well, from an indigenous perspective, it documents the author’s insights into the social interactions and internal politics of the evaluation conference “culture.” | In an environment where M ori approaches to evaluation are developing quickly, with ever-widening influence, this article is an attempt to capture the theoretical roots of Kaupapa M ori evaluation approaches. From a range of Kaupapa M ori theorists, six principles are drawn and their relevance to evaluation theory and practice is discussed. These principles are then mapped to major movements in evaluation theory, illustrating how Kaupapa M ori theory-based evaluation, arising as a unique praxis within the context of Aotearoa New Zealand, has strong alignment with international developments. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,453 |
Based on the comparison of experimental results to field study results, the relevance and significance of various similitude parameters for snowdrift modelling is discussed. A series of wind tunnel model tests were carried out on a single building and groups of buildings, both on-ground and above-ground. Results of snowdrift profiles and volumes are presented. | When high-speed trains run on a snowy railway line in cold weather, a large amount of snow and ice will accumulate on the brake calipers, which can lead to huge safety problems. In this paper, to s... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,454 |
We investigate the superconducting proximity effect in clean ferromagnetic layers with rough boundaries. The subgap density of states is formed by Andreev bound states at energies which depend on trajectory length and the ferromagnetic exchange field. At energies above the gap, the spectrum is governed by resonant scattering states. The resulting density of states, measurable by tunneling spectroscopy, exhibits a rich structure, which allows us to connect the theoretical parameters from experiments. | Majorana fermions are particles identical to their own antiparticles. They have been theoretically predicted to exist in topological superconductors. Here, we report electrical measurements on indium antimonide nanowires contacted with one normal (gold) and one superconducting (niobium titanium nitride) electrode. Gate voltages vary electron density and define a tunnel barrier between normal and superconducting contacts. In the presence of magnetic fields on the order of 100 millitesla, we observe bound, midgap states at zero bias voltage. These bound states remain fixed to zero bias, even when magnetic fields and gate voltages are changed over considerable ranges. Our observations support the hypothesis of Majorana fermions in nanowires coupled to superconductors. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,455 |
This paper describes an attempt to present living stem tissue with defined mechanical stress in a spatial configuration which can be easily interpreted in section. We have applied compressive stress to a growing Coleus internode in vivo, using stainless-steel spring-clips which act through a double-edged glass interface of known area. We have found that cambial activity consisting of cell division and enlargement continues even under applied compressive stress ranging up to 20 atm. Tissue reactions to applied stress are discussed in terms of the equilibration of forces propagating through the tissue before, during, and after the presentation of externally applied stress. THE NOTION that mechanical pressure may be able to control the plane of orientation of new cell walls dates back to the work of Kny (1902). More recent studies by this author (Lintilhac, 1974a; Lintilhac and Vesecky, 1980) have offered preliminary evidence that cell wall orientation in actively dividing plant tissues may be considered to correspond with the trajectories of the lines of principal stress as they exist within a meristematic tissue at the moment of cell plate orientation. The verification of this possibility has led us in a search for simple methods of applying stress to living plant tissues in order to achieve some control over division-wall orientation through manipulation of the stress-mechanical environment | One key aspect of cell division in multicellular organisms is the orientation of the division plane. Proper division plane establishment contributes to normal plant body organization. To determine the importance of cell geometry in division plane orientation, we designed a three-dimensional probabilistic mathematical model to directly test the century-old hypothesis that cell divisions mimic soap-film minima. According to this hypothesis, daughter cells have equal volume and the division plane occurs where the surface area is at a minimum. We compared predicted division planes to a plant microtubule array that marks the division site, the preprophase band (PPB). PPB location typically matched one of the predicted divisions. Predicted divisions offset from the PPB occurred when a neighboring cell wall or PPB was directly adjacent to the predicted division site to avoid creating a potentially structurally unfavorable four-way junction. By comparing divisions of differently shaped plant cells (maize [Zea mays] epidermal cells and developing ligule cells and Arabidopsis thaliana guard cells) and animal cells (Caenorhabditis elegans embryonic cells) to divisions simulated in silico, we demonstrate the generality of this model to accurately predict in vivo division. This powerful model can be used to separate the contribution of geometry from mechanical stresses or developmental regulation in predicting division plane orientation. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,456 |
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90°, decelerated to zero velocity in less than 25 μs, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed. | One of the simplest, and most completely treated, fields of application of quantum mechanics is the theory of atoms with one or two electrons. For hydrogen and the analcgous ions He+, Li++, etc., the calculations can be performed exactly, both in Schrodinger’s nonrelativistic wave mechanics and in Dirac’s relativistic theory of the electron. More specifically, the calculations are exact for a single electron in a fixed Coulomb potential. Hydrogen-like atoms thus furnish an excellent way of testing the validity of quantum mechanics. For such atoms the correction terms due to the motion and structure of atomic nuclei and due to quantum electrodynamic effects are small and can be calculated with high accuracy. Since the energy levels of hydrogen and similar atoms can be investigated experimentally to an astounding degree of accuracy, some accurate tests of the validity of quantum electrodynamics are also possible. Finally, the theory of such atoms in an external electric or magnetic field has also been developed in detail and compared with experiment. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,457 |
A key issue in RBAC systems is how to efficiently handle the user authorization process. That is, whether or not to grant a user's request to acquire a set of requested permissions or to activate a set of requested roles in a single session. The presence of hybrid hierarchies as well as the cardinality and dynamic separation of duty constraints make the issue more complex. In this paper, we define this issue as the user authorization query problem consisting of a role mapping problem and an activation checking problem. We also propose a set of algorithms to solve the role mapping and the activation checking problems. We show that our model is practical and flexible, and can deal with various cases in presence of the hybrid hierarchy and cardinality/DSoD constraints. | ABSTRACT With the increasing availability of networks and the advancements in their underlying infrastructure of mobile devices, access control and authorization issues will be enablers of future technologies in collaborative environments. Recent works demonstrate efforts to dynamically authorize users without prior knowledge and with no security configuration attributes or roles previously assigned to them. Moreover, current role-based engineering approaches construct role hierarchies without reflecting the organizational structure, since they do not take into account structural organizational characteristics. In this paper we propose an innovative role structure, not solely dependent on naming methods but also that takes into account organizational as well as functional characteristics to provide a practical role assignment methodology between organizations in a collaborative environment. More specifically, we argue that beyond the fact that a role represents a job assignment to perform certain function(s), it is also a composite element representing several organizational characteristics such as organizational function, organizational domain and level of authority. The proposed role structure enables role-to-role assignment as external nonlocal users request access in a particular information system (e.g., people on the move, users logged in from a collaborative organization) and acquire local role(s). A clear advantage in the proposed framework is its flexibility in the role assignment process, since the proposed role decomposition does not require an exact match of predefined credentials. The methodology is autonomous, as no prior trust establishment is required between interactive organizations, expendable as new organizations can join the collaboration without affecting the existing ones, flexible as it does not affect the local access control policy, scalable as the collaboration can increase arbitrary and efficient as the comparison methodology guarantees the selection of the appropriate local role, if such one exists. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,458 |
A system that facilitates airplane maintenance provides decision support for finding the root-cause of a failure from observed symptoms and findings. Such system provides diagnostic advice listing the most probable causes and recommending possible remedial actions. Furthermore, its goal is to reduce the number of delays and cancellations and unnecessary parts removal, which add significant costs to airplane maintenance operations. A Bayesian belief network, model-based approach is presently being used for building such diagnostic models. The paper describes the pertinent issues in using such models. | Elicitation of probabilities is one of the most laborious tasks in building decision-theoretic models, and one that has so far received only moderate attention in decision-theoretic systems. We propose a set of user interface tools for graphical probabilistic models, focusing on two aspects of probability elicitation: (1) navigation through conditional probability tables and (2) interactive graphical assessment of discrete probability distributions. We propose two new graphical views that aid navigation in very large conditional probability tables: the CPTREE (Conditional Probability Tree) and the sCPT (shrinkable Conditional Probability Table). Based on what is known about graphical presentation of quantitative data to humans, we offer several useful enhancements to probability wheel and bar graph, including different chart styles and options that can be adapted to user preferences and needs. We present the results of a simple usability study that proves the value of the proposed tools. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,459 |
A solution is presented for the stresses, both shear and normal, in adhesive-bonded joints between orthotropic adherends. The types of joint considered are stepped lap joints and smoothly tapered joints. The influences of important geometrical and material properties are studied for specific joints utilising metals and fibre-reinforced composites. | Metallic bolted flanges and pipes have both been increasingly replaced by fibre-reinforced polymer materials in many applications which deal with extreme harsh environments such as oil, chemical, marine, etc. This is not only due to the fibre-reinforced polymer material’s resistance to the chemical reaction but also due to their inherent mechanical properties of high strength to weight ratio. However, very little research has been published regarding bolted flange joints made of fibre-reinforced polymer materials. Also, the availability of standards and relevant design codes are very limited for bolted fibre-reinforced polymer flange joints. Hence, the design guidelines, dimensional considerations and selection of fabrication methods for the bolted fibre-reinforced polymer flange joints have yet to be optimized fully. For instance, the ASME Boiler and Pressure Vessel Code, section X and ASME PCC-1-2013 appendix O or other similar standards do not include specific rules for the design of the bolted fibre-r... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,460 |
LetA be a positive integral power of a natural, conformally covariant differential operator on tensor-spinors in a Riemannian manifold. Suppose thatA is formally self-adjoint and has positive definite leading symbol. For example,A could be the conformal Laplacian (Yamabe operator)L, or the square of the Dirac operator ::: Open image in new window ::: . Within the conformal class\(\left\{ {g = e^{2w} g_0 |w \in C^\infty (M)} \right\}\) of an Einstein, locally symmetric “background” metricgo on a compact four-manifoldM, we use an exponential Sobolev inequality of Adams to show that bounds on the functional determinant ofA and the volume ofg imply bounds on theW2,2 norm of the conformal factorw, provided that a certain conformally invariant geometric constantk=k(M, g o A) is strictly less than 32π2. We show for the operatorsL and ::: Open image in new window ::: that indeedk < 32π2 except when (M, g o ) is the standard sphere or a hyperbolic space form. On the sphere, a centering argument allows us to obtain a bound of the same type, despite the fact thatk is exactly equal to 32π2 in this case. Finally, we use an inequality of Beckner to show that in the conformal class of the standard four-sphere, the determinant ofL or of ::: Open image in new window ::: is extremized exactly at the standard metric and its images under the conformal transformation groupO(5,1). | We consider the constant Q-curvature metric problem in the given conformal class on conic 4-manifolds and study related differential equations. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,461 |
Novel dual-band microstrip bandpass filters (BPFs) are proposed with good in-between isolation. A half-wavelength stepped-impedance resonator (SIR) is characterized, aiming at producing the two resonant frequencies at 2.4 and 5.2GHz. Two types of coupled microstrip lines in the parallel and anti-parallel formats are then investigated in terms of unified equivalent J-inverter network. Extensive results are derived to show their frequency-distributed coupling performances under the different coupling lengths. The parallel coupled line is modeled to bring out a promising transmission zero between the two resonant frequencies so as to achieve a good in-between isolation. In this way, a two-stage BPF is designed to exhibit their dual-band frequency responses with good isolation. A three-stage dual-band BPF is in final optimally designed and its predicted performance is further confirmed in experiment. | A new configuration of dual-band filter design is presented in this paper. Stepped-impedance transmission-line sections are used as the tunable dual-band resonators. New coupling structures and matching networks at input and output are also proposed to achieve a dual-band characteristics. Three filters with their second passband at 1.5, 2, and 2.5 times the fundamental frequency are designed as examples, and they are all verified by experimental results. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,462 |
We report on the first single-junction GaSb solar cell epitaxially grown on a Si substrate. A control stand-alone GaSb solar cell was primarily fabricated, which demonstrated a 5.90% efficiency (AM1.5G). The preparation, growth and manufacturing procedures were then adapted to create the GaSb-on-Si solar cell. The hybrid device resulted in a degraded efficiency for which comparison between experimental and simulated data revealed dominant non-radiative recombination processes. Material and electrical characterization also highlighted the impact of anti-phase domains and boundaries and threading dislocation density on the shunt resistance of the cell. Nevertheless, the GaSb-on-Si cell performance is close to recent results on the integration of GaSb solar cells on GaAs, despite a much larger lattice mismatch (12% vs 8%). Routes for improvement, concerning the material quality and cell structure, are proposed. This work lays the foundations of a GaSb-based multi-junction solar cell monolithically integrated on Si. | The role of antiphase domains formed on GaAs grown on Ge is analyzed by means of conductive atomic force microscopy. The correlation of the derivative topography scans with the conductive scans shows a constant current value in most of the surface under study; although at certain locations high current leaks occur causing an inhomogeneous conductivity through the GaAs layer as the density of antiphase domains increases. This result implies that the existence of antiphase domains decreases the parallel resistance of solar cells, helping to understand the impact of these defects on the electrical behavior of these devices | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,463 |
The maximum lifetime data gathering and aggregation (MLDA) problem is concerned with maximizing the system lifetime T so that we can perform T rounds of data gathering with in-network aggregation, given the initial available energy of the sensors. A solution of value T to the MLDA problem consists of a collection of aggregation trees together with the number of rounds each such tree should be used in order to achieve lifetime T. We describe a combinatorial iterative algorithm for finding an optimal continuous solution to the MLDA problem that consists of up to n-1 aggregation trees and achieves lifetime To, which depends on the network topology and initial energy available at the sensors. We obtain an alpha-approximate optimal integral solution by simply rounding down the optimal continuous solution, where alpha = (To-n+1)/To. Since in practice To Gt n, alpha ap 1. We get asymptotically optimal integral solutions to the MLDA problem whenever the optimal continuous solution is omega(n). Furthermore, we demonstrate the efficiency and effectiveness of the proposed algorithm via extensive experimental results. | The rapid advances in processor, memory, and radio technology have enabled the development of distributed networks of small, inexpensive nodes that are capable of sensing, computation, and wireless communication. Sensor networks of the future are envisioned to revolutionize the paradigm of collecting and processing information in diverse environments. However, the severe energy constraints and limited computing resources of the sensors, present major challenges for such a vision to become a reality.We consider a network of energy-constrained sensors that are deployed over a region. Each sensor periodically produces information as it monitors its vicinity. The basic operation in such a network is the systematic gathering and transmission of sensed data to a base station for further processing. During data gathering, sensors have the ability to perform in-network aggregation (fusion) of data packets enroute to the base station. The lifetime of such a sensor system is the time during which we can gather information from all the sensors to the base station. A key challenge in data gathering is to maximize the system lifetime, given the energy constraints of the sensors.Given the location of n sensors and a base station together with the available energy at each sensor, we are interested in finding an efficient manner in which data should be collected from all the sensors and transmitted to the base station, such that the system lifetime is maximized. This is the maximum lifetime data gathering problem. In this paper, we describe novel algorithms, with worst-case running times polynomial in n, to solve the data gathering problem with aggregation in sensor networks. Our experimental results demonstrate that the proposed algorithms significantly outperform previous methods in terms of system lifetime. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,464 |
Magnesiowustite is likely the second most abundant and probably weakest lower-mantle phase. Its deformation properties will therefore influence the rheological and dynamic behaviour of this region. In this study magnesiowustite aggregates with a composition of Mg 0.8 Fe 0.2 O have been deformed under dry conditions in axial compression at a confining pressure of 300 MPa and temperatures from 1200 to 1400 K (0.41 T m n =4.0±0.2 and an activation energy for creep of Q =327±5 kJ/mol. Deformation in the dislocation creep regime is corroborated by the development of a crystallographic preferred orientation (texture), which is consistent with simultaneous slip on the {100} and {110} slip planes in the 〈110〉 direction. Microstructures show the rapid formation of a subgrain boundary network indicating that mobility of dislocations is high and the recovery rate is fast. | We report a first combination of diamond anvil cell radial x-ray diffraction with in situ laser heating. The laser-heating setup of ALS beamline 12.2.2 was modified to allow one-sided heating of a sample in a diamond anvil cell with an 80 W yttrium lithium fluoride laser while probing the sample with radial x-ray diffraction. The diamond anvil cell is placed with its compressional axis vertical, and perpendicular to the beam. The laser beam is focused onto the sample from the top while the sample is probed with hard x-rays through an x-ray transparent boron-epoxy gasket. The temperature response of preferred orientation of (Fe,Mg)O is probed as a test experiment. Recrystallization was observed above 1500 K, accompanied by a decrease in stress. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,465 |
As one kind with the best comprehensive performance of various honeycombs, triangular honeycomb is an important structure to achieve lightweight. Focusing on the deficiency of the non-optimized macro-material distribution in uniform triangular honeycomb, a design and modeling method of variable-density triangular honeycomb structures was proposed. With a three-point bending beam as the design object, type and sizes of honeycomb cells were specified beforehand. The beam was topology-optimized and the density results were mapped to the relative density matrix of cells. The rapid and automatic modeling of variable-density triangular honeycomb was realized with the cyclic definitions of the User-Defined Features (UDF). The simulation results show that the mechanical performance of variable-density triangular honeycomb is better than uniform honeycomb and the efficiency of the proposed method is validated. | The finite-element methodology is presented to evaluate the energy absorption performance of staggered triangular honeycombs under in-plane crushing loadings at impact velocities of 50–300 m/s. The minimum dynamic cushioning coefficient is proposed to characterize the maximum energy absorption efficiency of staggered triangular honeycombs. When all configuration parameters are constant, the energy absorption per unit volume is proportional to the square of the impact velocity; for a given impact velocity, the energy absorption per unit volume is related to the ratio of the cell wall thickness to the edge length by a power law and to the expanding angle by complicated analytical equations. The maximum energy absorption efficiency is insensitive to the impact velocity. Only for the smaller ratio of the cell wall thickness to the edge length does the maximum energy absorption efficiency increase with the increasing expanding angle. At a given impact velocity there is a threshold ratio of the cell wal... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,466 |
This study was aimed at identifying the influence of the temperature transient on the creep–fatigue behavior of a steam turbine rotor. Especially, the steam temperature fluctuations during the steady state operation phase could lead the stress to the oscillation, which also contributes to the fatigue damage. Toward this end, in-service operating data during startup, shutdown and steady state operation phases was chosen to investigate the creep–fatigue damage of a 1000 MW steam turbine rotor. A viscoplastic constitutive model with damage was presented to describe creep–fatigue deformation behavior. A significant growth in creep damage was found under the influence of the temperature fluctuation compared to the creep damage under the stable temperature condition. In addition, steam temperature fluctuation induced the larger thermal gradient and temperature difference at the location where is closer to the rotor surface. The correlation of the stress range due to these temperature fluctuations has been established by carrying out the transient thermo-mechanical FE analysis. Frequent thermal fluctuations during the steady state operation phase were identified as one of the most influential factors for the creep–fatigue damage of the steam turbine rotor. | The aim of this paper is the analysis of inelastic behavior under periodic cyclic loading regimes for materials showing recovery effects. Starting with the Armstrong–Frederick type model and applyi... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,467 |
Deployable space structures have long been investigated as a means for packaging the desired solution within the confines of the launch environment. In this study, the design of a highly compact reflector that can be stowed in a 1U CubeSat is addressed. The ideal diameter of the finished reflector is 1 meter. In order to accomplish this objective, a folding method is developed and design constraints are derived from the packaging requirement. A design method is presented in which the deployed shape is divided into gores and flattened for manufacturing. Constraints on the shape of the gores are imposed in order to produce a flat configuration with desirable stowing characteristics. Two iterations of the design are presented with deployed diameters of 0.8 and 0.5m and final stowed diameters of 16 and 14cm respectively. | This paper presents a novel scheme to biaxially package and deploy flat membranes, in which the thickness of the membrane is accounted for through the novel concept of slipping folds. The membrane is divided into parallel strips connected by slipping folds, and specially chosen wrapping profiles that require zero slip along the edges of the membrane are identified. This packaging scheme avoids the kinematic incompatibilities that in other schemes result in local buckles and wrinkles that increase the deployment force and permanently deform the membrane. The paper also presents a scheme to apply uniform uniaxial prestress to the deployed membrane, as well as a two-stage deployment scheme. Packaging efficiencies of up to 83% have been demonstrated for meter-scale models, although for large membranes the packaging efficiency approaches 100%. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,468 |
A dual one-way ranging system (DOWR) provides very high precision range measurements between two carrier phase transceiver-receiver systems by combining the one-way range measurements from each system. A key requirement for the DOWR system is the synchronization of the two one-way range measurement times, and this requirement makes it necessary to interpolate the raw one-way phase measurements toward a common epoch. This interpolation process may degrade numerical accuracy under large time-tag offsets. This study proposed a new interpolation process to reduce the degradation. Numerical simulation analysis was performed to validate the performance of the proposed method. | Wireless high-precision time synchronization between distributed nodes is the basis of autonomous application of nodes. In this paper, the signal transmission mode between nodes and the baseband processing algorithm of receivers are designed. On the basis of dual one-way ranging measurement and signal design system with semi-data-free modulation, the signal is divided into pilot branch without information and data branch with information. In the aspect of signal acquisition, coherent joint acquisition algorithm is used, and in the aspect of signal tracking, fusion algorithm is used to track code and carrier phase. Finally, the detection probability of the receiver and the mean square deviation of tracking error are simulated to verify the superiority of the coherent joint acquisition algorithm and the fusion tracking algorithm. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,469 |
Chemical warfare agents such as sarin are highly toxic, and detection of even trace levels is important. Using a hydrogel film containing a built-in two-dimensional chemical potential gradient, we demonstrate the detection of a sarin simulant under conditions potentially as low as a level 1 (6.90 × 10–9 mg/cm3 for 10 min) Acute Exposure Guideline Level sarin exposure. Specifically, the sarin simulant diisopropyl fluorophosphate (DFP) is aerosol-deposited on a hydrogel film containing a built-in ionic chemical gradient and the enzyme, diisopropyl fluorophosphatase (DFPase). DFPase degrades the DFP, releasing fluoride ions. The fluoride ions are then concentrated by the gradient to a miniature electrochemical sensor embedded in the hydrogel providing a 30-fold amplification of the fluoride ion signal, which is an indication of exposure to DFP, relative to a gradient-free system. This method is general for agents which hydrolyze into chemically detectable ionic species. | Results are presented from Brownian dynamics simulations and from experimental measurements of self-diffusion coefficients of monovalent ions in systems of oppositely charged polymers. The simulations were carried out in ordered and in random polyion systems. The ordered systems consisted of parallel straight chains on a square lattice, while in the other systems the straight polymer chains were randomly oriented. At low polymer concentrations there was good agreement between the results obtained in both types of systems. However, when the polyion concentration was increased, the ion diffusion was slower in the random than in the ordered systems | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,470 |
The time-varying design flood can make full use of the measured data, which ::: can provide the reservoir with the basis of both flood control and operation ::: scheduling. This paper adopts peak over threshold method for flood sampling ::: in unit periods and Poisson process with time-dependent parameters model for ::: simulation of reservoirs time-varying design flood. Considering the ::: relationship between the model parameters and hypothesis, this paper presents ::: the over-threshold intensity, the fitting degree of Poisson distribution and ::: the design flood parameters are the time-varying design flood unit period and ::: threshold discriminant basis, deduced Longyangxia reservoir time-varying ::: design flood process at 9 kinds of design frequencies. The time-varying ::: design flood of inflow is closer to the reservoir actual inflow conditions, ::: which can be used to adjust the operating water level in flood season and ::: make plans for resource utilization of flood in the basin. | Annual maximum flood (AMF) sampling remains the most popular approach to flood frequency analysis. An alternative, the “peaks over threshold” (POT) approach, deals with the selection of over-threshold values. However, the POT approach remains under-employed mainly because of the complexities associated with its use. Among the difficulties are the choice of threshold and the selection of criteria for retaining flood peaks. The literature remains sparse and incoherent concerning the various elements and complexities of the POT model. The purpose of the present paper is to shed some light on some of the recurrent and most important questions with regard to the practice of POT modeling, and to make a first step in establishing a set of coherent practice-oriented guidelines for the use of the POT model. This paper reviews tests and methods useful for modeling the process of over-threshold values, the choice of the threshold level, the verification of the independence of the values and the stationarity of the process, and also presents an application. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,471 |
A traditional Boost Inverter generates output more than the applied DC-input. However, boost converter exhibits highly nonlinear control to output response. A Dynamic linearizing modulator (DLM) was used to control a boost converter which improves the large signal linearity of the converter at higher operating frequency. The DLM controlled boost converter has a conversion ratio which is highly dependent on the design of the modulator. These design limitations are described in this paper. Methods to overcome these limitations are proposed. Based on these proposals, an improved control strategy is validated using simulation and experiments. | Various methods to linearize the control-to-output behavior of a boost converter are discussed. Most of the previously reported linearizing techniques are not suitable when the reference input amplitude or frequency is large. In this paper, a dynamic linearizing modulator for the boost converter is proposed, which transforms the open-loop converter into a linear amplifier with an operating frequency as high as one-fifth the switching frequency. The modulator generates a duty ratio by comparing the nonlinear part of the boost converter dynamic equation with a sine wave reference voltage on a cycle-to-cycle basis. The technique exhibits superior audio susceptibility due to the feedforward of input voltage. The formulation, implementation, and verification of this technique are discussed. Experimental results show the validity of the technique for a reference input frequency up to one-fifth the switching frequency. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,472 |
In this paper, we focus on printed circuit boards (PCB) and their components arrangement optimization problem, which is derived from electronic surface mounting manufacturing process. It includes two tasks: the sequencing of PCBs and the assignment of components on PCBs to different mounting machines. A taboo search (TS) with kick strategy is proposed to solve this problem: (1) ordinal optimization (OO) is applied to obtain a favorable initial solution. It compensates for the dependence on the initial solution of taboo search and contributes to obtain a better result in a large possibility. (2) kick strategy is embedded into taboo search, and the global searching ability of the algorithm is greatly strengthened. It not only inherits the characteristic of previous local optimization, but also avoids being trapped in the specific region which fails to find a better solution. The experimental result shows that the algorithm is effective for solving the PCBs and their components arrangement optimization problem. | In this paper, we propose a tabu search approach for solving the permutation flow shop scheduling problem. The proposed implementation of the tabu search approach suggests simple techniques for generating neighborhoods of a given sequence and a combined scheme for intensification and diversification that has not been considered before. These new features result in an implementation that improves upon previous tabu search implementations that use mechanisms of comparable simplicity. Also, better results were obtained than those produced by a simulated annealing algorithm from the literature. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,473 |
The present invention relates to providing a device used in a wireless network including a first patch member whose two facing corners are cut and a first micro strip feeding line providing a signal by being connected to one side of the first patch member, in order to be used in the wireless network. The first micro strip feeding line forms 45 degree angle actually at one side of the first patch member. An antenna further includes a second patch member whose two facing corners are cut and a second micro strip feeding line connected to one side of the second patch member. The second micro strip feeding line forms 45 degree angle actually as to one side of the second patch member. The patch members form an antenna array being being serially connected. One patch member indicates a host patch member, and the other patch member indicates a parasitic patch member. | In this paper, a phased array designed for millimeter-wave mobile handset is demonstrated. The low profile antenna array is capable of covering a quarter of the entire space with 11dBi peak gain when beam is electronically steered. Four such arrays on each side of the mobile device would provide full spatial coverage. The antenna design is based on waveguide structure and allows for an all metallic mobile phone case when integrated. The specific antenna presented in this paper is designed around 28GHz with 2GHz bandwidth for the future Samsung 5G cellular system. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,474 |
The construction industry is the second largest industry of the country after agriculture. It makes a significant contribution to the national economy and provides employment to large number of people. The use of various new technologies and deployment of project management strategies has made it possible to undertake projects of mega scale. In its path of advancement, the industry has to overcome a number of challenges. However, the industry is still faced with some major challenges, including housing, disaster resistant construction, water management and mass transportation. Recent experiences of several new mega-projects are clear indicators that the industry is poised for a bright future. It is the second homecoming of the civil engineering profession to the forefront amongst all professions in the country. | Construction is one of the important industries employing a large number of people on its workforce. A wide range of activities are involved in it. Due to the advent of industrialization and recent developments, this industry is taking a pivotal role for construction of buildings, roads, bridges, and so forth. The workers engaged in this industry are victims of different occupational disorders and psychosocial stresses. In India, they belong to the organized and unorganized sectors. However, data in respect to occupational health and psychosocial stress are scanty in our country. It is true that a sizable number of the workforce is from the unorganized sectors ― the working hours are more than the stipulated hours of work — the work place is not proper ― the working conditions are non-congenial in most of the cases and involve risk factors. Their wages are also not adequate, making it diffi cult for them to run their families. The hazards include handling of different materials required for construction, and exposure to harsh environmental conditions like sun, rain, and so on. On account of this, in adverse conditions, it results in accidents and adverse health conditions cause psychosocial strain and the like. They are victims of headache, backache, joint pains, skin diseases, lung disorders like silicosis, other muscular skeletal disorders, and so on. The repetitive nature of the work causes boredom and the disproportionate earning compared to the requirements puts them under psychological stress and strain and other abnormal behavioral disorders. The Government of India has realized the importance of this industry and has promulgated an Act in 1996. The state government are being asked to adhere to this, although only a few states have partially enforced it. In this article, attempts have been made to review some of the important available articles for giving a broad idea of the problem and for furtherance of research in this fi eld. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,475 |
Applying nonlinear optimization techniques such as quasi-Newton methods to aerodynamic shape optimization problems requires the calculation of gradients of a given objective function. An effective way of calculating such gradients is through the use of the so-called adjoint equations. To achieve fast convergence in the optimization algorithm, accurately computed gradients are needed. In the computation of such gradients the discretization of the problem and the choice of boundary conditions are two important aspects. These issues are studied in the context of shape optimization of a quasi-1D nozzle using physically relevant boundary conditions. Isentropy is enforced at the inlet boundary, and the static pressure is specified at the outlet boundary for subsonic flows. A cell-centered finitevolume discretization with a standard implementation of the boundary conditions is applied, and the corresponding numerical scheme and numerical boundary conditions for the adjoint equations are derived in a fully discrete sense. Numerical experiments at subsonic and transonic speeds, show that the gradient evaluations are accurate enough to obtain satisfactory convergence of the quasi-Newton algorithm. | In this paper, we study a design problem for a duct flow with a shock. The presence of the shock causes numerical difficulties. Good shock-capturing schemes with low continuity properties often cannot be combined successfully with efficient optimization methods requiring smooth functions. A remedy studied in this paper is to introduce the shock location as an explicit variable. This allows one to fit the shock and yields a problem with sufficiently smooth functions. We prove the existence of optimal solutions, Frechet differentiability, and the existence of Lagrange multipliers. In the second part, we introduce and investigate the discrete problem and study the relations between the optimality conditions for the infinite-dimensional problem and the discretized one. This reveals important information for the numerical solution of the problem. Numerical examples are given to demonstrate the theoretical findings. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,476 |
Effect of time delay (τ) on intracellular calcium dynamics with non-Gaussian noises in transmission processes of intracellular Ca2+ is studied by means of second-order stochastic Runge-Kutta type algorithm. By simulating and analyzing time series, normalized autocorrelation function, and characteristic correlation time of cytosolic and calcium store’s Ca2+ concentration, the results exhibit: (i) intracellular calcium dynamics’s time coherence disappears and stability strengthens as τ → 0.1s; (ii) for the case of τ 0.1s, they show different variation as τ increases, the former changes from underdamped motion to a level line, but the latter changes from damped motion to underdamped motion; and (iii) at the moderate value of time delay, reverse resonance occurs both in cytosol and calcium store. | Considering the time-delayed feedback and environmental perturbations in spin-crossover system, we construct a stochastic delayed differential equation to study the state transitions from the low spin (LS) state to the high spin (HS) state in spin-crossover solids. It is shown that the delayed feedback and noise can induce optical bistability and state transitions. The mean first-passage time (MFPT) of the transition from the LS state to the HS state as the function of the noise intensity exhibits a maximum, and the noise-enhanced stability is observed. However the MFPT decreases with increase of the delayed feedback intensity, thus the delayed feedback accelerates the conversion from the LS state to the HS state. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,477 |
Wool fibers are subjected to severe mechanical processing following scouring, which results in physical damage. This study investigates the role of physical processing in changing the physical and chemical properties of the fibers. Removal of surface-bound lipids following physical processing is minimal, but there are significant morphological changes related to an increase in the chemical susceptibility of the fibers to chemical attack. The finding is demonstrated by the more effective removal of bound lipids from fibers in the form of top than from aqueous scoured fibers. | The model described in Part I has been evaluated using as a starting point fiber strength and withdrawal-force parameters derived from tensile testing. These param eters were then adjusted to give an optimum fit of the theory to published data. The differences in the measured and the fitted values could probably be mainly ascribed to differences between the wool types measured and those used in the published data and to differences between the slow loading in testing and the more rapid loading that occurs in carding. With optimum adjusted values of the parameters, it was possible to get good agreement between the predicted and the actual fiber length distributions after carding, except for a tendency for the proportion of short fibers to be underestimated. This was no doubt due to the nonconformity of actual fibers to some of the assumptions made. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,478 |
Two experimental slurry bubble column facilities comprising of 10.8 and 30.5 cm diameter columns and appropriate for conducting hydrodynamic and heat transfer studies are described. The average and local gas holdup data are reported for the air-water system as a function of air velocity. The holdups for the three phases are also reported for the air-water-glass beads system over a range of air velocity values. The air holdup data are compared with the predictions of some of the commonly used correlations. The heat transfer coefficient for a 19 mm diameter cylindrical probe and the two- and three-phase dispersions are measured as a function of air velocity. Most of these hydrodynamic and heat transfer data correspond to the churn turbulent regime and the values obtained on the two columns differ appreciably from each other under similar operating conditions. This fact indicates that the scaleup of slurry bubble columns could be quite difficult on the basis of data obtained on the bench and pilot-plant scal... | Knowledgeoftheheattransfercoefficientisanessentialprerequisiteforanyindustrialgas/liquidbubble column reactor design. In this paper, experiments were carried out in a laboratory scalebubble column using air–water and 10wt% glycerin–air solution systems. Experimental values ofthe heat transfer coefficient were compared with some of the previous published correlations andwere also compared with the model predicted by ANN in our previous work (Ahmedzeki, 2007).The ANN model was found to be better than all previous published correlations. %AARE was8.2 and %standard deviation was 7.85. A mechanistic model was also developed to analyze thesystem. The resulting correlation was a %AARE of 17.5 and %standard deviation of 15. Boththe above models and the experimental results compared well with the previous published corre-lations.KEYWORDS: heat transfer coefficient, bubble columns, ANN | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,479 |
Considering both plane stress and plane strain conditions, the plastic zone size and the crack tip opening displacement of an interface crack between a coating and a semi-infinite substrate under a normal load on the crack surfaces are investigated by the mixed-mode Dugdale model. In the model, stresses applied in the plastic zones satisfy the Von Mises yield criterion. The plastic zone size can be calculated by satisfying the condition that the complex stress intensity factors vanish. After the plastic zone size is solved, the crack tip opening displacement can be obtained by dislocation theories. In numerical examples, a uniform load is considered, and the effects of the normalized elastic modulus (the ratio of the elastic modulus of the coating to the elastic modulus of the substrate) and the normalized crack depth (the ratio of the coating thickness to the interface crack length) on the normalized plastic zone size and the normalized crack tip opening displacement are examined. Numerical examples show in the case of thin coatings, the value of the normalized plastic zone size decreases with increasing the normalized elastic modulus. | The plane problem of a Dugdale crack under mixed mode loading is investigated. An exact closed form solution is given and the corresponding crack displacements are discussed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,480 |
In this paper, it studies the problems of the on-line identification on the nonlinear and time-lag SISO dynamic system. It puts forward the recurrent structure to linearize the input neurons of the neural network which can describe the feasibility of the algorithm, so the neural network has the dynamic on-line identification capability. Simulation results show that the input linearization dynamic recurrent network has a strong self-adaptability and robustness. It gives a new method for SISO nonlinear dynamic system identification. | A type of recurrent neural network is discussed which provides the potential for the modelling of unknown nonlinear systems with multi-inputs and multi-outputs. The proposed network is a generalization of the network described by Elman (1989). It is shown that the proposed network with appropriate neurons in the context layer can model unknown nonlinear systems. Based on a PID-like training objective function, the learning algorithm of the proposed network is considerably faster through the introduction of dynamic backpropagation, which is used to estimate the weights of both the feedforward and feedback connections. The techniques have been successfully applied to the modelling nonlinear plants and simulation results are included. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,481 |
We study the boundedness of weighted multilinear operators given by products of finite vectors of Calderon-Zygmund operators. We also investigate weighted estimates for bilinear operators related to Schrodinger operator. | In this paper, we characterize the weighted Hardy space related to the Schrodinger operator , with V a non-negative potential satisfying a reverse Holder inequality, by atomic decomposition and Riesz transforms. We also get a characterization of its dual space through a weighted Carleson measure. Then we prove the boundedness of some classical operators associated to on the weighted BMO space . | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,482 |
With the tremendous growth of information available on the Web, there is a dire need of classifying it for the ease of use and for the brisk accessibility. The classified data can be used for making recommendations. This paper discusses and compares three classifiers applied on movie data-set using WEKA 3.7 data mining tool. The data is classified into five different classes namely: bad, ok, average, good and excellent. A discussion about true positive rate, false positive rate, precision, and recall based on confusion matrix for each class is carried out. Subsequently the boundary visualization of data is captured in form of a graph, and a meaningful comparison between Zero R rule, Naive Bayes classifier and J48 tree is done by experimentation and analysis. In this paper, an attempt has been made to analyze the best classifier for movie data based on users' ratings and then the classification is used for making the recommendations for users. | This article examines how product and consumer characteristics moderate the influence of online consumer reviews on product sales using data from the video game industry. The findings indicate that online reviews are more influential for less popular games and games whose players have greater Internet experience. The article shows differential impact of consumer reviews across products in the same product category and suggests that firms' online marketing strategies should be contingent on product and consumer characteristics. The authors discuss the implications of these results in light of the increased share of niche products in recent years. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,483 |
Highly supersaturated solid solutions of selenium or sulfur in silicon were formed by ion implantation followed by nanosecond pulsed laser melting. n+p photodiodes fabricated from these materials exhibit gain (external quantum efficiency >3000%) at 12 V of reverse bias and substantial optoelectronic response to light of wavelengths as long as 1250 nm. The amount of gain and the strength of the extended response both decrease with decreasing magnitude of bias voltage, but >100% external quantum efficiency is observed even at 2 V of reverse bias. The behavior is inconsistent with our expectations for avalanche gain or photoconductive gain. | Se doped silicon is prepared by femtosecond-laser irradiation of Si coated with Si/Se bilayer films. The effects of Se film thickness on optical and electrical properties of Se doped silicon are studied. With the increase of the thickness of dopant film, the infrared absorptance increases significantly at wavelengths from 1100 to 2200 nm. At −10 V bias, the responsivities at 1064 nm for samples prepared with Se film thicknesses of 50, 75, 100 and 125 nm are 0.310, 0.786, 0.911 and 1.22 A/W, respectively. This investigation demonstrates that the increase of doping concentration is beneficial to improve infrared absorption and photoresponse of Se doped silicon. This observation has potential to improve the property of Se doped silicon and facilitate its application in photoelectric devices. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,484 |
Rhodamine-WT dye, ethylene, and propane were injected at three sites along a 21.6-kilometer reach of the West Fork Trinity River below Fort Worth, Texas. Complete dye concentration versus time curves and peak gas concentrations were measured at three cross sections below each injection. The peak dye concentrations were located and samples were collected at about three-hour intervals for as many as six additional cross sections. These data were analyzed to determine the longitudinal dispersion coefficients as well as the gas desorption coefficients using both standard techniques and a numerical routing procedure. The routing procedure, using a Lagrangian transport model to minimize numerical dispersion, provided better estimates of the dispersion coefficient than did the method of moments. At a steady flow of about 0.76 m3/s, the dispersion coefficient varied from about 0.7 m2/s in a reach contained within a single deep pool to about 2.0 m2/s in a reach containing riffles and small pools. The bulk desorption coefficients computed using the routing procedure and the standard peak method were essentially the same. The liquid film coefficient could also be obtained using the routing procedure. Both the bulk desorption coefficient and the liquid film coefficient were much smaller in the pooled reach than in the reaches containing riffles. | Materials engineers easily recognize that the conduction of heat within solids is fundamental to understanding and controlling many processes. We could cite numerous examples to emphasize the importance of this topic. Some important applications that fall in this category include estimating heat losses from process equipment, quenching, or cooling operations where the cooling rate of a part actually controls its microstructure and hence its application, and solidification. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,485 |
A projection pursuit cluster model is used to resolve the problem of Karstic water pollution evaluation. First, the projection pursuit cluster model is stated. Then, a genetic algorithm is applied to optimise the projection direction of the projection pursuit cluster model, and the steps of the genetic algorithm are introduced in detail. Finally, a case study of Karstic water pollution evaluation is presented. The projection pursuit cluster model is a powerful tool in analysing complex multifactor problems, and it is also a new method for Karstic water pollution evaluation. | This paper presents an approach based on Projection Pursuit and fuzzy rule extraction combining new hybrid method of classification system. This method is the first to use projection pursuit technology to deal with training set of sample dimensionality reduction and in accordance with the sample classification. According to the results of the classification and the best value projection, using trapezoid distribution method extraction fuzzy rules, producing three types of fuzzy membership function. Finally, in accordance with Fuzzy nearness value to determined the sample under the credit level. The results of experiment showed this method of classification accuracy than the traditional credit evaluation techniques have markedly improved, the reliability is better, has a good application value. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,486 |
A three-terminal superconducting device composed of a semiconductor-coupled Josephson junction and an oxide-insulated gate is fabricated. A p-type Si single-crystal film having a 100-nm thickness is used for the semiconductor layer. Two superconducting electrodes of the Josephson junction correspond to source and drain electrodes of the three-terminal device. Josephson tunneling current flows between source and drain electrodes, and is controlled by the gate bias voltage. | Spin transistors are a new concept device that unites an ordinary transistor with the useful functions of a spin (magnetoresistive) device. They are expected to be a building block for novel integrated circuits employing spin degrees of freedom. The interesting features of spin transistors are nonvolatile information storage and reconfigurable output characteristics: these are very useful and suitable functionalities for various new integrated circuit architectures that are inaccessible to ordinary transistor circuits. This article reviews the current status and outlook of spin transistors from the viewpoint of integrated circuit applications. The device structure, operating principle, performance, and features of various spin transistors are discussed. The fundamental and key phenomena/technologies for spin injection, transport, and manipulation in semiconductors and the integrated circuit applications of spin transistors to nonvolatile logic and reconfigurable logic are also described. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,487 |
The lodestar of contract conflicts, i.e., the principle of party autonomy,1 has long been controversial in Latin-American legal literature and practice.2 This principle is of course irreconcilable with the classical Savignian approach, which authors and courts throughout the subcontinent still profess to follow.3 Such doctrinal scruples, however, did not stop European courts from adopting it for the simple reason that party autonomy is indispensable for the conduct of international trade and commerce. Indeed, it is difficult to envision a safe and orderly conduct of business across national borders-in Kozolchyk's terms a "juridical road" on which the free flow of goods | Article 3 of the Hague Principles on Choice of Law in International Contracts is the first quasi-legislative text on choice of law to allow explicitly for the choice of non-state law also before state courts. This paper, forthcoming in a Festschrift, puts the provision into a broader context, discusses their drafting history and particular issues involved in their interpretation. It also provides a critical evaluation. Article 3 does not respond to an existing need, and its formulation, the fruit of a compromise between supporters and opponents of choosing non-state law, makes the provision unsuccessful for state courts and arbitrators alike. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,488 |
The electrochemical permeation test is one of the most used methods for characterising hydrogen diffusion in metals. The flux of hydrogen atoms registered in the oxidation cell might be fitted to obtain apparent diffusivities. The magnitude of this coefficient has a decisive influence on the kinetics of fracture or fatigue phenomena assisted by hydrogen and depends largely on hydrogen retention in microstructural traps. In order to improve the numerical fitting of diffusion coefficients, a permeation test has been reproduced using FEM simulations considering two approaches: a continuum 1D model in which the trap density, binding energy and the input lattice concentrations are critical variables and a polycrystalline model where trapping at grain boundaries is simulated explicitly including a segregation factor and a diffusion coefficient different from that of the interior of the grain. Results show that the continuum model captures trapping delay, but it should be modified to model the trapping influence on the steady state flux. Permeation behaviour might be classified according to different regimes depending on deviation from Fickian diffusion. Polycrystalline synthetic permeation shows a strong influence of segregation on output flux magnitude. This approach is able to simulate also the short-circuit diffusion phenomenon. The comparison between different grain sizes and grain boundary thicknesses by means of the fitted apparent diffusivity shows the relationships between the registered flux and the characteristic parameters of traps. | Hydrogen-enhanced localized plasticity (HELP) is an acceptable mechanism for hydrogen embrittlement which is based on the experimental observations and the theoretical computations. The underlying principle in the HELP theory is that the presence of hydrogen causes the localization of the slip bands which results in the decrease of the fracture strength. In a sample under plane-strain tensile stress, plastic instability can lead to either the concentration of plastic flow in a narrow neck or bifurcation from homogeneous deformation into a mode of an exclusively localized narrow band of intense shear. Recently, it has been demonstrated that the presence of hydrogen can indeed induce shear banding bifurcation at macroscopic strains. By using a steady-state equilibrium equation for hydrogen diffusion analysis, the effect of hydrogen on the bifurcation of a homogeneous deformation in a plane-strain tension specimen into a necking or a shear localization mode of deformation has already been studied. In the present research, using a transient hydrogen diffusion analysis and introducing a new constitutive equation accompanied by considering the reduction in the local flow stress upon hydrogen dissolution into the lattice, the effect of hydrogen on shear localization is investigated. In addition, progress has been made in that, the changes in the distribution of the total and trapping hydrogen concentrations through the loading time and particularly during the development of the necking event have been determined. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,489 |
The various regions of the gas production rate curve were investigated and related to the similar behaviour of the boiling curve. The effects of temperature, electrolyte concentration and electrode material on the maximum value of the electrical current density were studied for both electrodes. Especially, the effect of electrolyte concentration is essential. In agreement with theoretical predictions, gas bubble growth during electrolysis is mass diffusion controlled, i.e. the bubble radius is proportional to the square root of time. The bubble growth rate increases at increasing electrical current density. Also, gas bubble behaviour was studied for different geometries and various types of electrodes. | Hydrogen produced by water electrolysis with renewable electricity is a reliable, affordable and environmental friendly energy carrier for future energy supply and storage. Alkaline water electrolysis is a well matured technique and proved to be suitable for large-scale applications. Materials development for alkaline water electrolyzers is still of interest for academia and industry to address the issues of low compatibility to renewable power sources. A lab-scale system for alkaline water electrolysis was developed, aiming to advance materials development and to bridge the intrinsic properties of materials with their performance under realistic operating conditions. As the smallest pressure-type electrolyzer, it is capable of working at 30 bar and 80 °C with continuous liquid electrolyte circulation. Experimental studies investigate the influence of temperature, pressure, and intrinsic properties of materials on voltage efficiency and hydrogen purity. With appropriate analysis, links between material sp... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,490 |
The electrorheological (ER) behaviour of particulates in an external a.c. electric field can be explained by the structuring of dispersed particles caused by the oscillations of induced dipoles in the particles. In this work, the effect of an a.c. electric field on a water-activated ER fluid was investigated under both continuous and oscillatory shear. An a.c. frequency-dependent behaviour of a model ER fluid was found at large deformations (continuous shear). Specifically, it was observed that the Bingham yield value decreased as the a.c. frequency increased and above 500 Hz was independent of frequency, implying that the fluid has a response time of 2 ms. However, there was no significant dependence on the a.c. frequency at small deformations (oscillatory shear); the elastic modulus was found to be constant over the range 10–1500 Hz. This dichotomy has been resolved by recalling that the Bingham yield value is a measure of the energy needed to break the structure, whilst the elastic modulus is more a measure of the extent of structure. The data suggest that in the oscillatory experiments, which were obtained in the linear viscoelastic region, the structure is not destroyed, whilst in the continuous shear experiments the structure is broken and at high frequencies, above 500 Hz, the structure does not have time to reform. | The electrorheological effect produced by an ER-Fluid with an applied electric field is not yet fully understood. However, it is significant to understand how the viscosity increases, and thus, the... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,491 |
We discuss the design of a Digital Micromirror Device-based Snapshot Spectral Imaging (DMD-SSI) system for NIR ::: wavelengths. A pair of low/high dispersion glasses was selected for building an NIR relay-lens and a double-Amici ::: prism, which are needed for generating Compressive Sensing (CS) measurements in experimental settings. Aberrations ::: of the system were simulated using the Zemax software, which were considered in a numerical model of the system. CS ::: measurements were generated using this model accounting for those aberrations. We evaluated the quality of the ::: spatial/spectral data-cubes reconstructed using those non-ideal CS measurements and discuss possible solutions of ::: enhancing the reconstruction quality. | Compressive spectral imaging (CSI) has demonstrated to be a feasible technique for capturing the 3D spatio spectral information of a scene through less measurements than the Nyquist rate. The coded aperture snapshot spectral imaging (CAS-SI) is an example of a CSI optical architecture, which has been proposed to work on the visible electromagnetic spectrum. Due to the rich information contained in the infrared spectrum, in this paper, we mathematically model and demonstrate the implementation of a broadband CASSI system covering the visible and the near infrared spectra between 448 nm to 1436 nm. Particularly, we developed a Digital Micromirror Device-based CSI system, which implements dual-band CS measurement processes of 3D spatio-spectral scenes. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,492 |
Utilizing the technology of image recognition, a design scheme of monitoring device of risks caused by external damages on overhead transmission lines was presented based on embedded DSP platform. Based on binocular stereo vision, the algorithm for detecting intrusions in the overhead transmission line corridor was investigated. Applying binocular cameras to obtain scenes of high-voltage overhead transmission lines, the functions calculating the distance between each conductor and intrusion and space coordinates were developed. The accuracy of the three-dimensional positions of the invasion objects obtained by binocular stereo vision algorithm was verified in the laboratory. The field availability of detecting external damages with binocular stereo vision algorithm was analyzed. | This paper proposes a method of 3D(three- dimensional) object recognition using binocular parallax. The calibration object is a 2D(two-dimensional) object and a calibration label is placed on its plane. The internal, external, and distortion parameters of the camera are collaborated by taking pictures of the calibration object in different angles. This research allows image distortions caused by the camera to be calibrated, allowing the image coordinate of the characteristic point to better match with its actual coordinate. After calibration, the depth, localization, and identification of stereo vision of the image developed by the left and right cameras are optimized; the coordinate, distance, and the angle of rotation can be precisely identified. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,493 |
The Laboratório de Ciências Radiológicas is developing an irradiator for neutron survey meters calibration. Part of this work is related to the characterization of the neutron source that will be used in the irradiator. Therefore, a source of 241Am-Be(α,n) was characterized according to the following attributes: neutron energy distribution, anisotropy and emission rate. In order to make these values into high-level metrological references traceable by the Bureau International des Poids et Mesures, these measurements were taken at the Neutron Laboratory part of the Laboratório Nacional de Metrologia das Radiações Ionizantes. Results obtained for the source spectrum have strong adherence to the reference spectrum established by ISO 8529-1. The new laboratory for neutron calibration will allow calibration in an approximate ambient dose equivalent ranging 20-4500 μSv/h. | The Manganese sulphate solution has been used for neutron metrology through the method of Manganese Bath. This method uses physical parameters of manganese sulphate solution to obtain its corrections. This work established a functional relationship, using the gravimetric method, between those physical parameters: density, concentration and hydrogen to manganese ratio. Comparisons were done between manganese sulphate solution concentration from the Manganese Bath system of Laboratory of Metrology of Ionising Radiation and estimated values from the functional relationship obtained, showing percentage difference of less than 0.1%. This result demonstrates the usefulness in the correlation of the physical values of the solution to the MB. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,494 |
This paper investigates the relationship between the two parameters, aquifer media and hydraulic conductiv-ity, and assesses their reliability for aquifer vulnerability assessment. To evaluate the possible non-inde-pendence of the parameters in question, sensitivity analysis procedure was used in a GIS environment. The procedure was tested in three areas where aquifer vulnerability was assessed, corresponding to three different hydrogeological settings. The applications demonstrate that non-independence is confirmed and is more evident in alluvial and volcano-pyroclastic aquifers. | This proceedings, "Groundwater: An Endangered Resource", contains papers presented at the 27th Congress of the International Association of Hydraulic Research (IAHR) entitled "Water for a Changing Global Community." In many places in the world, groundwater is threatened either by excessive use or by contamination resulting from industrial activities, agricultural practices and waste disposal methods. Over the last two decades many researchers and practitioners have concentrated their efforts on addressing these issues. This proceedings brings together some of the results of these efforts. The papers cover six general topics: heterogeneous aquifers; groundwater remediation and risk management; stochastic approaches to subsurface hydrology; drainage water relationship to water quality; groundwater modeling; and water and contaminant movement in porous and fractured media. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,495 |
This paper deals with a boost dc-dc converter for fuel cell application. In fuel cell e lectric vehicles application, a high power boost dc-dc converter is adopted to adjust the output voltage, current and power of fuel cell engine to meet the vehicle requirements. One of challenge in designing a boost converter for high power application is how to handle the high current at the input side. In this paper an interleaved boost dc-dc converter is proposed for current sharing on high power application. Moreover, this converter also reduces the fuel ripple current. Performance of the interleaved boost converter is tested through simulation and experimental results. Keywords: component; Interleaved Boost Converter; Fuel Cell Electric Vehicle; high power application. | The aim of this study is to propose a experimental verification for single-phase to three phase drive system composed of two parallel single-phase rectifiers, a three-phase inverter and an induction motor. Apart from traditional application in dc motor drives, new applications of BDC include energy storage in renewable energy systems, fuel cell energy systems, Hybrid Electric Vehicles (HEV) and Uninterruptible Power Supplies (UPS). A dc-dc converter is always required to allow energy exchange between storage device and the rest of system. In HEV applications, BDCs are required to link different dc voltage buses and transfer energy between them. A non-isolated bi-directional dc-dc converters is used in our project to achieve better efficiency. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,496 |
Summary ::: Novel epoxy resins with unsaturated ester chains (maleate, M-series) were synthesized from sodium lignosulfonate and maleic anhydride. Epoxy resins with saturated ester chains (succinate, S-series) were also synthesized from succinic anhydride. Thermal properties of the obtained epoxy resins were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). The glass transition temperatures (Tg's) increased with increasing ligosulfonate content in epoxy resins for both M- and S-series. Tgvalues of epoxy resins in M-series were ca. 15 °C higher than those in S-series. The activation energies of curing reaction in M- and S-series were ca. 59.6 and 66.1 kJ mol−1, respectively. Thermal degradation temperatures (Td's) were almost constant at 350 °C regardless of lignosulfonate contents in epoxy resins in both M- and S-series. Mass residues at 500 °C increased with increasing lignosulfonate contents in epoxy resins in both M- and S-series. | Lignin containing substantial aromatic rings and high content of carbon has been employed as carbonizing agent to investigate the flame retardancy in the lignin/ammonium polyphosphate (APP) intumescent flame retardant (IFR) system. In addition, owing to the abundant phenolic and aliphatic hydroxyl groups, lignosulfonate, which is considered as a renewable aromatic macropolyols, substituted part of diethylene glycol (DEG) and copolymerized with isocyanate to produce lignosulfonate-based rigid polyurethane (LRPU) foams. Thermal stability was characterized by thermogravimetric analysis (TGA), and flame retardancy was investigated by limiting oxygen index (LOI) and cone calorimetry testing (CCT). Lignosulfonate increases thermal stability of LRPU foams and LRPU containing 15 wt% of lignosulfonate based on DEG (L15RPU) give rise to the best thermal stability. When 15% of lignosulfonate incorporated in the LRPU, reduced the heat release rate (HRR) and total heat release (THR) value 21 kW/m2 and 13 MJ/m2, respectively, and postponed 96 s time-to-peak carbon monoxide production than that of pure DEG rigid polyurethane (RPU) foam, the LOI values increased progressively with lignosulfonate content increasing. These results showed that lignosulfonate polyol may substitute polyol to produce lignosulfonate-based RPU foam and the presence of lignosulfonate could improve the flame retardancy. The mass loss gradually decreases with increasing APP addition, and the highest char yield was obtained from LRPU5 foam which at the lignosulfonate-to-APP ratio is 1:5. At the lignosulfonate-to-APP ratio of 1:5, the LOI value increased over 30%, and the HRR value reduced and the time-to-peak HRR postponed significantly. In addition, LRPU5 foams give rise to the lowest effect heat combustion (EHC) value, less smoke, and carbon monoxide (CO) production. Lignosulfonate acts as carbonizing agent in the lignosulfonate/APP IFR system, and the best fire retardancy is obtained at 1:5 of lignosulfonate-to–APP ratio. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,497 |
The dependence of the magnitude of the Zener relaxation effect on temperature, T , is measured on polycrystalline samples of α Ag-Zn of three compositions. The experimental results for the relaxation strength, Δ G , are found to obey the equation: Δ G = T 0 (T − T c ) , where T 0 and T c are constants. This equation, originally derived by Zener, is rederived here under more general assumptions. The quantity T c , which is interpreted as the critical temperature for self-induced ordering of the alloy, is found to be equal to 175°K, 140°K and 97°K for alloys containing 33.5, 30.2 and 24.2 at.% Zn, respectively. | Many instruments used to measure viscoelastic properties are only capable of subjecting a sample to a limited range of loading frequencies. For thermorheologically simple materials, it is assumed that a change in temperature is equivalent to a shift of the viscoelastic behavior on the log frequency or time axis. For many materials, time–temperature superposition appears to work well for modulus or compliance curves over three decades of time or frequency, but some deviations are known if the window is expanded to five or six decades. To apply a more stringent test of the validity of time–temperature superposition, broadband viscoelastic spectroscopy is used to isothermally study polymethylmethacrylate and low-density polyethylene at several temperatures in the glassy region. Shear modulus and damping (tan δ) are measured isothermally over a wide range (up to 11 decades) of time and frequency. Results indicate that, while modulus curves can be approximately superimposed, the damping (tan δ) curves change in height and shape with temperature. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,498 |
Optical Ground Station 1 (OGS1) is the first of a new breed of dedicated ground terminals to support NASA’s developing space-based optical communications infrastructure. It is based at NASA’s Optical Communications Telescope Laboratory (OCTL) at the Table Mountain Observatory near Wrightwood, CA. The system will serve as the primary ground station for NASA’s Laser Communications Relay Demonstration (LCRD) experiment. This paper presents an overview of the OCTL telescope facility, the OGS1 ground-based optical communications systems, and the networking and control infrastructure currently under development. The OGS1 laser safety systems and atmospheric monitoring systems are also briefly described. | The Laser Communications Relay Demonstration (LCRD) will implement an optical communications link between ::: a pair of Earth terminals via an Earth-orbiting satellite relay. Optical turbulence over the communication ::: paths will cause random ::: uctuations, or fading, in the received signal irradiance. In this paper we characterize ::: losses due to fading caused by optical turbulence. We illustrate the performance of a representative relay link, ::: utilizing a channel interleaver and error-correction-code to mitigate fading, and provide a method to quickly ::: determine the link performance. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 24,499 |
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