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Quantum spin, tensor product: a long time relationship | Should it be obvious that independent quantum states are composed by taking the tensor product? | Should it be obvious that independent quantum states are composed by taking the tensor product? | eng_Latn | 4,200 |
Infinite cartesian product from Herbert Enderton's Elements of set theory | Definition of the Infinite Cartesian Product | Tensor product vs. Cartesian Product for composite quantum systems | eng_Latn | 4,201 |
Scalable Replay-Based Replication For Fast Databases | Rethinking main memory OLTP recovery | Quantum Recommendation Systems | kor_Hang | 4,202 |
Learning with Errors is easy with quantum samples | Efficient Fully Homomorphic Encryption from (Standard) LWE | A Pseudo-Response Regulator is misexpressed in the photoperiod insensitive Ppd-D1a mutant of wheat (Triticum aestivum L.) | eng_Latn | 4,203 |
What books should I read to learn more about quantum physics? | What book should I read to understand quantum physics? | What is the best book on quantum mechanics published in 2015? | eng_Latn | 4,204 |
What is "quantization"? Give one example | What is Quantization? | What is Quantization? | eng_Latn | 4,205 |
Understanding latent sector errors and how to protect against them | A new intra-disk redundancy scheme for high-reliability RAID storage systems in the presence of unrecoverable errors | The geometry of generalized Pauli operators of N-qudit Hilbert space, and an application to MUBs | eng_Latn | 4,206 |
Which book is most useful for studying quantum mechanics? | Which book will be more prefer to study quantum mechanics? | What is the best book on quantum mechanics published in 2015? | eng_Latn | 4,207 |
define qua | Qua is defined as in the function of, or in the capacity of. An example of qua is an assistant manager acting as manager while the manager is out sick; the assistant manager qua manager. in the function, character, or capacity of; as: the President qua Commander in Chief. Origin of qua. | Look up QA/QC in Wiktionary, the free dictionary. QA/QC is the combination of quality assurance, the process or set of processes used to measure and assure the quality of a product, and quality control, the process of ensuring products and services meet consumer expectations. | ita_Latn | 4,208 |
Generation of sheet currents by high frequency fast MHD waves | Geometry of fast magnetosonic rays, wavefronts and shock waves, Physics Letters A 380, 3817-3822 | IDH1 and IDH2 mutations are rare in pediatric myeloid malignancies | eng_Latn | 4,209 |
Self-consistent particle simulation of three-dimensional dc magnetron discharge | Influence of Operating Parameters on Target Erosion of Rectangular Planar DC Magnetron | The hidden-charm strong decays of the $Z_c$ states | eng_Latn | 4,210 |
The Electrical Resistance of Iron Wires and Permalloy Strips at Radiofrequencies | The ratio of a.c. to d.c. resistances of iron wires and permalloy strips has been measured in the frequency range 1.5–6.0 megacycles per sec. Empirical equations obtained are compared with existing theoretical equations derived on the assumption of constant permeability. | We theoretically propose a method to identify $\ifmmode\pm\else\textpm\fi{}s$-wave order parameter in recently discovered Fe-pnictide superconductors. Our idea uses the Riedel anomaly in ac-Josephson current through a $\text{SI}(\ifmmode\pm\else\textpm\fi{}\text{S})$ (single-band $s$-wave superconductor/insulator/$\ifmmode\pm\else\textpm\fi{}s$-wave two-band superconductor) junction. We show that the Riedel peak effect leads to vanishing ac-Josephson current at some values of biased voltage. This phenomenon does not occur in the case when the $\ifmmode\pm\else\textpm\fi{}s$-wave superconductor is replaced by a conventional $s$-wave one so that the observation of this vanishing Josephson current would be a clear signature of $\ifmmode\pm\else\textpm\fi{}s$-wave pairing state in Fe-pnictide superconductors. | eng_Latn | 4,211 |
Relaxation of spheromak configurations with open flux | Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak | Transcriptional activation of HIF-1 by a ROS-ERK axis underlies the resistance to photodynamic therapy | eng_Latn | 4,212 |
Losses in sinusoidal filter chokes | Predicting iron losses in soft magnetic materials with arbitrary voltage supply: an engineering approach | Completely Stale Transmitter Channel State Information is Still Very Useful | eng_Latn | 4,213 |
Large-scale distribution of discrete auroras and field-aligned currents. | Euler potentials for two layers with non-constant current densities in the ambient magnetic field aligned to the layers | The transport of low density lipoprotein-derived cholesterol to the plasma membrane is defective in NPC1 cells. | eng_Latn | 4,214 |
Methane conversion in low-temperature plasma | Non Catalytic Methane Formation from Syngas in the Dielectric Barrier Discharge Plasma, Initiated by Microsecond Pulses | Practical verification of topology for a high voltage pulse converter for non-thermal plasma generation | eng_Latn | 4,215 |
A fluid model of the edge plasma in low-temperature discharges containing beam electrons | Modeling plasmas in analytical chemistry—an example of cross-fertilization | Constant delay enumeration with FPT-preprocessing for conjunctive queries of bounded submodular width | eng_Latn | 4,216 |
Visual inspection and motion control for invessel tile servoing tasks in a Tokamak vessel | Design and Material Selection for ITER First Wall/Blanket, Divertor and Vacuum Vessel | Decommissioning of the Tokamak Fusion Test Reactor | eng_Latn | 4,217 |
Fundamental limitations of the local approximation for electron distribution function and fluid model in bounded plasmas | Ambipolar field role in formation of electron distribution function in gas discharge plasma | Neural network representability of fully ionized plasma fluid model closures | eng_Latn | 4,218 |
Measurement of plasma parameters in the far-field plume of a Hall effect thruster | Evaluation of various probe designs for measuring the ion current density in a Hall thruster plume . IEPC-2017-336 | No evidence for apparent extent between parallels as the basis of the Poggendorff effect | eng_Latn | 4,219 |
Plasma physics and controlled nuclear fusion research 1974 | Effect of resonant magnetic perturbations on COMPASS-C tokamak discharges | Introduction to Plasma Physics and Controlled Fusion | eng_Latn | 4,220 |
This paper presents the braking control performance of a vehicle anti-lock brake system featuring an electrorheological (ER) fluid. As a first step, a cylindrical type of ER valve is devised and its pressure controllability is experimentally confirmed. Then, a hydraulic booster for amplifying the field-dependent pressure drop obtained from the ER valve is constructed and its pressure amplification is demonstrated by presenting the pressure tracking control performance. Subsequently, the governing equation of the rear wheel model is derived by considering the braking force distribution, and a sliding mode controller for achieving the desired slip rate is designed. The controller is then realized through the hardware-in-the-loop simulation method and controlled responses are presented in the time domain. In addition, computer animations for the braking performance under unladen and laden conditions are presented, and a comparison of the proportioning valve and the proposed ER valve pressure modulator is made. | Conventional electrorheological (ER) fluids consist of suspensions of microparticles in usually nonconducting fluids with a different dielectric constant. The interparticle interaction, and hence, the rheology of ER fluids, is determined by an external electric field, which polarizes grains and thus induces additional dipole-dipole coupling. The electric field plays a role of a new degree of freedom that allows us to ?tune? the interaction between particles. This makes the phase diagram of ER fluids remarkably diversified. Here, we report on the experimental investigations of ?ER plasmas,? where the control of the interparticle interaction by an externally applied electric field is due to distortion of the Debye spheres that surround microparticles in a plasma. Interactions in ER plasmas under weak ac fields are mathematically equivalent to those in conventional ER fluids. Microgravity experiments as well as molecular dynamics simulations show a phase transition from an isotropic to an anisotropic plasma states as the electric field is increased. The variational Gibbs-Bogoliubov approach allows us to recover the phase diagram of ER plasmas, which includes string fluids and anisotropic solid phases. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 4,221 |
The goal of the Fermilab high field magnet (HFM) R&D project is to explore various designs and production technology of a high-field, low-cost Nb/sub 3/Sn accelerator magnet suitable for a future Very Large Hadron Collider (VLHC). The model under fabrication consists of two-layer shell-type coil with 43.5 mm aperture and cold iron yoke. The Fermilab concept of magnet design and fabrication technology involves some specific features such as curing of half-coil with ceramic binder/matrix before reaction, and then simultaneous reaction and impregnation of both half-coils to get a "coil pipe" structure. The coil pipe is mechanically supported by the vertically-split iron yoke locked by two aluminum clamps and a thick stainless steel skin. 2D finite element analysis has been performed to study and optimize the prestress in the coil and in the structural elements at room temperature and at 4.2 K. Model description, material properties and the results of mechanical analysis are reported in this paper. | The superconducting 11 T dipole magnets developed at CERN for the HL-LHC project are equipped with coils manufactured from Nb3Sn Rutherford cables and following the wind and react fabrication technique. The brittleness of the multifilamentary structure of the Nb3Sn within the cable strands exposes the coils to permanent performance degradation when subjected to excessive strain during assembly and operation. This paper will show the characterisation of cable stacks (10-stack) under compression using representative coil material in order to predict the behavior of the Nb3Sn coils. By means of standard mechanical measuring techniques and finite element analysis, the results from the 10-stack measurements are extrapolated to an actual and fully detailed coil cross section using two-dimensional imaging techniques. The stress distribution from the actual coil geometry are used to predict the stresses at the strand level and the filaments within the strand. The model of the strand and filaments is based on a scanning electron microscope image of a strand of interest within the original coil in order to provide a realistic geometry and a better representation of the stresses within the multifilament structure. The results from this multiscale approach have allowed for a better understanding of the stresses that are observed at the strand and filament level by accounting for the global stresses of the realistic coil geometry. | A 75-year-old woman suffered severe haemoptysis after insertion of a Swan-Ganz catheter in an intensive care unit. Control of the pulmonary artery haemorrhage was quickly and successfully achieved with stainless steel coils as the embolic material. | eng_Latn | 4,222 |
This paper addresses nuclear analysis on the Korean fusion demonstration reactor (K-DEMO) divertor to estimate the overall trend of nuclear heating values and displacement damages. The K-DEMO divertor model was created and converted by the CAD (Pro-Engineer™) and Monte Carlo automatic modeling programs as a 22.5° sector of the tokamak. The Monte Carlo neutron photon transport and ADVANTG codes were used in this calculation with the FENDL-2.1 nuclear data library. The calculation results indicate that the highest values appeared on the upper outboard target (OT) area, which means the OT is exposed to the highest radiation conditions among the three plasma-facing parts (inboard, central and outboard) in the divertor. Especially, much lower nuclear heating values and displacement damages are indicated on the lower part of the OT area than others. These are important results contributing to thermal-hydraulic and thermo-mechanical analyses on the divertor and also it is expected that the copper alloy materials may be partially used as a heat sink only at the lower part of the OT instead of the reduced activation ferritic-martensitic steel due to copper alloy's high thermal conductivity. | This paper presents a shutdown dose rate (SDR) calculation to estimate a newly developed preliminary concept of the equatorial port model for the Korean fusion demonstration reactor (K-DEMO). The equatorial port model was designed to provide effective radiation shielding abilities adopting the port shielding block and labyrinth structure, which was integrated into the modified K-DEMO neutronic analysis model by the Monte Carlo automatic modeling system. A rigorous two-step method was applied to couple transport (MCNP) and activation (FISPACT) codes according to three steps of calculation procedures. The results of neutron flux and decay gamma transport calculation for the equatorial port area have been indicated in this paper. The SDR calculation result near the equatorial port area reveals that a dose level in the equatorial port interspace was below $100~\mu $ Sv/h after 12 days of the shutdown. Shielding blocks and two labyrinth structures prove that they effectively attenuate neutrons on the current concept of the equatorial port 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 | 4,223 |
The R3B-Glad superconducting Magnet provides the field required for a large acceptance spectrometer, dedicated to the analysis of Reactions with Relativistic Radioactive ions Beams. In the framework of the FAIR Project to GSI and within NUSTAR physics program, the technical study started in 2006, and the engineering fabrication is undertaken. The magnetic field and active shielding are achieved by means of 6 superconducting trapezoidal racetrack coils made of a Rutherford type NbTi superconducting cable. The coils are indirectly cooled at an operating temperature of 4.5 K by a thermo-siphon circuit, and are designed to run at a nominal current of 3.6 kA. The corresponding maximum stored magnetic energy reaches 24 MJ. The quench protection is achieved by discharging the magnet in an external resistor, with a voltage to ground of ±500 V at the beginning of the discharge. The design and the characteristics of the quench protection system are described. The computational results of the quench protection for several scenarii are presented as well as the thermal and electromagnetic behavior of the coil cases. | The 9-m long superconducting model coil B0 was built to verify design parameters and exercise the construction of the barrel toroid magnet of ATLAS detector. The model coil has been successfully tested at CERN. An intensive test program to study quench propagation through the coil windings as well as the temperature distribution has been carried out. The coil is well equipped with pickup coils, voltage taps, superconducting quench detectors and temperature sensors. The current is applied up to 24 kA and about forty quenches have been induced by firing internal heaters. Characteristic numbers at full current of 24 kA are a normal zone propagation of 15 m/s in the conductor leading to a turn-to-turn propagation of 0.1 m/s, the entire coil in normal state within 5.5 s and a safe peak temperature in the windings of 85 K. The paper summarizes the quench performance of the B0 coil. Based on this experience the full-size coils are now under construction and first test results are awaited by early 2004. | 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 | 4,224 |
Sufficient conditions are determined for the unboundedness (unsolvability ‘in the large’) of the solutions of boundary value problems for a class ofquasilinear equations and systems of equations of parabolic type, describing the propagation of heat in media with non-linear heat conduction and volume liberation of energy. | Three types of blow-up for a fourth-order degenerate reaction-diffusion equation are studied by a combination of analytic and numerical methods. At the critical values of parameters, there occurs a variational problem with a countable set of solutions obtained by Lysternik--Shnirelman category theory, which then are extended to neighbouring values of parameters by a homotopy-like approach. | In this study, a two-dimensional axisymmetric computational model of spark discharge in air is presented to provide a better understanding of the dynamics of the process. Better understanding of the modeling issues in spark discharge processes is an important issue for the automotive spark plug community. In this work we investigate the evolution of the shock front, temperature, pressure, density, geometry, and flow history of a plasma kernel using various assumptions that are typically used in spark discharge simulations. A continuum, inviscid, heat conducting, single fluid description of the flow is considered with radiative losses. Assuming local thermal equilibrium, the energy input due to resistive heating is determined using a specified current profile and temperature-dependent gas electrical conductivity in the gap. The spark discharge model focuses on the early time flow physics, the relative importance of conduction and radiation losses, the influence of thermodynamic model choice and ambient pressure effects. | eng_Latn | 4,225 |
© 2002-2011 IEEE. Due to the improvement in the manufacturing of the superconductor, the superconducting magnets have been widely used in the areas such as magnetic resonance imaging (MRI), particle accelerators, and magnetic levitation systems. The transformer-rectifier flux pump is an effective method to energize the superconducting magnets. However, in the real system of the flux pump, some undesired dc current will be inevitably generated in the flux pumping system during the process of energizing the superconducting magnets. The undesired dc current will have many negative impacts such as slowing down the charging process, decreasing the final field of the superconducting magnets, and resulting in the failure of the whole system. This paper will focus on the origin of the undesired dc current in the flux pump, investigate the damage that the undesired dc current causes, and propose an effective method of removing the undesired dc current. The proposed method has greatly improved the performance of the flux pump. An experimental system is built and tests are carried out to verify the practicality and validity of the proposed method. | The dynamic resistance in a slab-like superconductor is calculated, taking into account a field-dependent critical current density. In superconductors carrying DC transport current in an AC external magnetic field, the dynamic resistance causes a transport loss which depends on the amplitude and frequency of this field as well as on the transport current. This resistance is calculated analytically in a critical-state model applied to a superconducting slab in a parallel field. The field has a general periodic time dependence and for the superconductor a relation between critical current and momentary magnetic field as in the Kim model is assumed. The dynamic resistance appears only at field amplitudes larger than the so-called threshold field, which depends on the transport current. The model predictions are compared with experimental results obtained with a Bi-2223/Ag tape at liquid-nitrogen temperature. At small field amplitude and at low transport current, the derived model predicts the observed dependence of dynamic resistance on field amplitude, field frequency and transport current. For a larger field amplitude and simultaneous high transport current, the resistance is found to be larger than the model predicts. This is probably due to the not completely slab-like geometry and/or to a different field dependence of the critical current density in a high AC field. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 4,226 |
Benchmarks of DEGAS 2 against EIRENE yield agreement to within 5% and comparable single processor run times. DEGAS 2 demonstrates a nearly linear increase in processing speed with the number of parallel processors. That speed is put to practical use here in the first runs of UEDGE coupled to DEGAS 2. The results of the coupled codes match those of coupled UEDGE and EIRENE. Additional algorithmic improvements such as use of the correlated sampling technique promise to make runs of the coupled UEDGE - DEGAS 2 codes practical for everyday use. | A design study of a fusion ignition research experiment (FIRE) is underway to investigate and assess near term opportunities for advancing the scientific understanding of self-heated fusion plasmas. The emphasis for the FIRE program is on understanding the behavior of plasmas dominated by alpha heating (Q≥5). Study activities have focused on the technical evaluation of a compact, high field, highly shaped tokamak. One of the key issues for the design is to find suitable plasma facing components (PFCs). We have investigated a variety of plasma edge and divertor conditions ranging from reduced recycling high heat flux conditions (attached) to reduced heat flux detached operation. The inner divertor detaches easily while impurities must be added to the outer divertor to achieve detachment. The outer divertor and private space baffle will have to be actively cooled. The plasma-facing surface of the divertor is tungsten bonded to a CuCrZr heat sink. The remainder of the PFCs are beryllium coated copper attached to the vacuum vessel. Plasma current disruptions impose strong constraints on the design. Appreciable PFC surface melting and evaporation and onset of ‘plasma shielding’ are expected. The forces induced on the PFC due to disruptions determine the size of the attachment of the PFC to the vacuum vessel. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 4,227 |
Current-voltage characteristics were measured in the mixed state of Y(1)Ba(2)Cu(3)O(7-delta) superconducting films in the regime where flux flow becomes unstable and the differential conductivity dj/dE becomes negative. Under conditions where its negative slope is steep, the j(E) curve develops a pronounced staircase-like pattern. We attribute the steps in j(E) to the formation of a dynamical phase consisting of the successive nucleation of quantized distortions in the local vortex velocity and flux distribution within the moving flux matter. | We report numerical simulations of large-amplitude oscillations of a trapped vortex line under a strong ac magnetic field $H(t)=H\sin\omega t$ parallel to the surface. The power dissipated by an oscillating vortex segment driven by the surface ac Meissner currents was calculated by taking into account the nonlinear vortex line tension, vortex mass and a nonlinear Larkin-Ovchinnikov (LO) viscous drag coefficient $\eta(v)$. We show that the LO decrease of $\eta(v)$ with the vortex velocity $v$ can radically change the field dependence of the surface resistance $R_i(H)$ caused by trapped vortices. At low frequencies $R_i(H) $ exhibits a conventional increases with $H$, but as $\omega$ increases, the surface resistance becomes a nonmonotonic function of $H$ which decreases with $H$ at higher fields. The effects of frequency, pin spacing and the mean free path $l_i $ on the field dependence of $R_{i}(H) $ were calculated. It is shown that, as the surface gets dirtier and $l_i$ decreases, the anomalous drop of $ R_{i}(H) $ with $H$ shifts to lower fields which can be much smaller than the lower critical magnetic field. Our numerical simulations also show that the LO decrease of $\eta(v)$ with $v$ can cause a vortex bending instability at high field amplitudes and frequencies, giving rise to the formation of dynamic kinks along the vortex. Measurements of $R_i(H)$ caused by sparse vortices trapped perpendicular to the surface can offer opportunities to investigate an extreme nonlinear dynamics of vortices driven by strong current densities up to the depairing limit at low temperatures. The behavior of $R_i(H)$ which can be tuned by varying the rf frequency or concentration of nonmagnetic impurities is not masked by strong heating effects characteristic of dc or pulse transport measurements. | 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 | 4,228 |
This article is devoted to the study of Dielectric Barrier Discharges (DBD) and afterglows obtained at atmospheric pressure in nitrogen. Electrical and optical analysis of the DBD reactor are carried out in order to characterize specific activated gaseous species, which can travel with low energy dispersion for long distances in tubes. A hypothesis for the explanation of the presence of long-lived species in such afterglows is finally explained as related to a solitary wave effect. | The Third International Workshop & Summer School on Plasma Physics (IWSSPP'08) organized by St Kliment Ohridsky University of Sofia, with co-organizers TCPA Foundation, Association EURATOM/IRNRE, The Union of the Physicists in Bulgaria, and the Bulgarian Academy of Sciences was held in Kiten, Bulgaria, at the Black Sea Coast, from 30 June to 5 July 2008. A Special Session on Plasmas for Environmental Issues was co-organised by the Institute of Plasmas and Nuclear Fusion, Lisbon, Portugal and the Laboratory of Plasmas and Energy Conversion, University of Toulouse, France. That puts the beginning of a series in Workshops on Plasmas for Environmental Issues, now as a satellite meeting of the European Physical Society Conference on Plasma Physics. As the previous issues of this scientific meeting (IWSSPP'05, J. Phys.: Conf. Series 44 (2006) and IWSSPP'06, J. Phys.: Conf. Series 63 (2007)), its aim was to stimulate the creation and support of a new generation of young scientists for further development of plasma physics fundamentals and applications, as well as to ensure an interdisciplinary exchange of views and initiate possible collaborations by bringing together scientists from various branches of plasma physics. This volume of Journal of Physics: Conference Series includes 38 papers (invited lectures, contributed talks and posters) devoted to various branches of plasma physics, among them fusion plasma and materials, dc and microwave discharge modelling, transport phenomena in gas discharge plasmas, plasma diagnostics, cross sections and rate constants of elementary processes, material processing, plasma-chemistry and technology. Some of them have been presented by internationally known and recognized specialists in their fields; others are MSc or PhD students' first steps in science. In both cases, we believe they will raise readers' interest. We would like to thank the members of both the International Advisory Committee and the Local Organizing Committee, the participants who sent their manuscripts and passed through the (sometimes heavy and troublesome) refereeing and editing procedure and our referees for their patience and considerable effort to improve the manuscripts. We greatly appreciate the financial support from the sponsors: the Department for Language Teaching and International Students at the University of Sofia, the Austrian Science and Research Liason Offices and the Bulgarian Nuclear Society. We would like to express our gratitude to the invited lecturers who were willing to pay the participation fee. In this way, in addition to the intellectual support they provided by means of their excellent lectures, they also supported the school financially. E Benova, F M Dias and Yu Lebedev | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 4,229 |
EXPERIMENTAL RESEARCH AND DEVELOPMENT OF HEAT POWER SUPPLY PROTOTYPE BASED ON HIGH-ENERGY PROCESSES IN SOLID MEDIUM INTERACTING WITH HYDROGEN IONS FLUX | A Possible Mechanism For Cold Fusion | ON COFINITELY WEAK ı SUPPLEMENTED MODULES | yue_Hant | 4,230 |
Strand production and benchmark testing for the ITER model coils | Testing of industrial Nb3Sn strands for high field fusion magnets | Completely Stale Transmitter Channel State Information is Still Very Useful | eng_Latn | 4,231 |
Calculation of eddy currents by dual energy methods | Optimal Cohomology Generators for 2-D Eddy-Current Problems in Linear Time | Lipoprotein Electrophoresis Should Be Discontinued as a Routine Procedure | eng_Latn | 4,232 |
NEUTRAL-POINT REGION IN PETSCHEK'S MODEL OF MAGNETIC-FIELD ANNIHILATION. | 3D magnetic reconnection and its application to solar flares | Evaluation of divergent N-echelon (s, nQ)-policies under compound renewal demand | yue_Hant | 4,233 |
A High Current, Subnanosecond Response Faraday Cup | Stability of Injection of a Subnanosecond High-Current Electron Beam and Dynamic Effects Within Its Rise Time | 101 Flux Decline in Ultrafiltration Processes | eng_Latn | 4,234 |
Stability of the Primakoff-Sedov blast wave and its generalizations | The Sedov self-similar point blast solutions in nonuniform media | Further studies on numerical instabilities of Godunov-type schemes for strong shocks | eng_Latn | 4,235 |
Design and performance of a facility to measure electromagnetic emissions from electric satellite thrusters | Electromagnetic Emissions from DC to 17 GHz from a Pulsed Plasma Thruster (PPT) | No iron fertilization in the equatorial Pacific Ocean during the last ice age | eng_Latn | 4,236 |
Acceleration of ions by electric field pulses in the inner magnetosphere | Acceleration of protons and heavy ions to suprathermal energies during dipolarizations in the near-Earth magnetotail | Theory and design of piezoelectric resonators immune to acceleration: present state of the art | eng_Latn | 4,237 |
Simulation of collisionless shocks in plasmas with high metallicity | The Hybrid Multiscale Simulation Technology | Collision Capacity Evaluation of RC Columns by Impact Simulation and Probabilistic Evaluation | eng_Latn | 4,238 |
Very-near-field plume simulation of a stationary plasma thruster | Approximate semi-analytical solutions for the steady-state expansion of a contactor plasma | Characterization of the NASA Langley Arc Heated Scramjet Test Facility using NO PLIF | eng_Latn | 4,239 |
Parasitic Magnetic Coupling in Voltage Measurement Setups for Impulse Current Tests | Arc Extinguishing Method of SPD Type 1 | No evidence for apparent extent between parallels as the basis of the Poggendorff effect | eng_Latn | 4,240 |
Two-dimensional dynamics of a high-temperature magnetized plasma in plasma switches | Study of Electron Beams in Wire Arrays at 1-MA $Z$-Pinch Generators | A solvable model for the basic properties of a simple magnetized plasma torus | eng_Latn | 4,241 |
Measuring the homogeneity of ceramic superconductors by eddy current probing | REVIEW ARTICLE SQUIDs for nondestructive evaluation | Implications of Spatial Heterogeneity for the Paradox of Enrichment | eng_Latn | 4,242 |
Using SOLPS to confirm the importance of parallel area expansion in Super-X divertors | UKAEA capabilities to address the challenges on the path to delivering fusion power | No evidence for apparent extent between parallels as the basis of the Poggendorff effect | eng_Latn | 4,243 |
A detailed calculation of the sensitivity of a cryogenic current comparator (CCC) has been completed. The model accounts for the current distribution on the closed external shield and the overlapped shield around the windings. Additional refinements to the model lead to excellent agreement with sensitivity measurements for a range of CCC geometries. | The sensitivity of an overlapped-tube cryogenic current comparator (CCC) has been calculated including the effect of an external shield. Dimensions of the shield, tube and pick-up coil can be optimised to give maximum sensitivity. Improvements in sensitivity by a factor of two or three are possible for a typical design. | The sensitivity of an overlapped-tube cryogenic current comparator (CCC) has been calculated including the effect of an external shield. Dimensions of the shield, tube and pick-up coil can be optimised to give maximum sensitivity. Improvements in sensitivity by a factor of two or three are possible for a typical design. | eng_Latn | 4,244 |
We report on the detection of the time-dependent B-field amplitude and topology in a laser-driven solenoid. The B-field inferred from both proton deflectometry and Faraday rotation ramps up linearly in time reaching 210 ± 35 T at the end of a 0.75-ns laser drive with 1 TW at 351 nm. A lumped-element circuit model agrees well with the linear rise and suggests that the blow-off plasma screens the field between the plates leading to an increased plate capacitance that converts the laser-generated hot-electron current into a voltage source that drives current through the solenoid. ALE3D modeling shows that target disassembly and current diffusion may limit the B-field increase for longer laser drive. Scaling of these experimental results to a National Ignition Facility (NIF) hohlraum target size (∼0.2cm^{3}) indicates that it is possible to achieve several tens of Tesla. | Recent experiments are showing possibilities to generate strong magnetic fields on the excess of 500 T with high-energy nanosecond laser pulses in a compact setup of a capacitor connected to a single turn coil. Hot electrons ejected from the capacitor plate (cathode) are collected at the other plate (anode), thus providing the source of a current in the coil. However, the physical processes leading to generation of currents exceeding hundreds of kiloamperes in such a laser-driven diode are not sufficiently understood. Here we present a critical analysis of previous results and propose a self-consistent model for the high current generation in a laser-driven capacitor-coil assembly. It accounts for three major effects controlling the diode current: the space charge neutralization, the plasma magnetization between the capacitor plates, and the Ohmic heating of the external circuit—the coil-shaped connecting wire. The model provides the conditions necessary for transporting strongly super-Alfvenic currents through the diode on the time scale of a few nanoseconds. The model validity is confirmed by a comparison with the available experimental data. | 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 | 4,245 |
Recently, it was reported that RF induction plasma of a pulse-modulated operating mode had been successfully generated, for the first time, at a sufficiently high electric power level for materials processing. The unique conditions in the plasma, such as a non-equilibrium situation at the instance of pulse-on and -off and the increase of chemically reactive radical species, as well as the time-dependent change of plasma temperature, is expected to offer the unique physico–chemical conditions necessary for materials processing. As the first step of the work directed to materials processing, the thermal and chemical interactions between plasma and solid materials were examined for both cases of pulse-modulated and continuous modes. Green compacts of titanium dioxide (TiO2), whose characteristics strongly depend on the formation of lattice defects and the incorporation of hydrogen, were treated in ArH2 plasma of continuous and pulse-modulated generation modes. The oxide disks were placed at the downstream of plasma flow. The sample position and the plasma generation pressure were changed as processing parameters. The plasma-treated specimens were characterized by X-ray diffractometry and the hydrogen content was measured. The plasma treatment gave a thermal effect, rather than a chemical one, on the surface of oxide specimens. The oxides were thermally reduced by the plasma treatment and showed a change of color at the surface, while XRD did not show a change of crystal structure. Comparing specimens treated in the pulse-modulated plasma with those treated in the continuous plasma, the disk specimens had less of a thermal effect on the plasma. | This paper presents a summary of fundamental principles and applications of modulated induction thermal plasmas that have been developed by the author's group. The modulated induction thermal plasma is established using a coil current that is modulated to the order of several hundreds of amperes at a millisecond time scale. Such a large current modulation enables the creation of a large disturbance in high-pressure and high-temperature plasmas. It also enables control of the temperature and radical density in thermal plasmas in a time domain. Examples are described for application of the modulated induction thermal plasma to surface modification. Thermally and chemically non- equilibrium effects are essential in temperature and radical density fields. The latest result is also presented for various applications of modulated induction thermal plasmas. Finally, dynamic behaviors of a recently developed arbitrary- waveform modulated induction thermal plasma are also introduced as a new type of modulated induction thermal plasma. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 4,246 |
FNAL and CERN are developing a twin-aperture 11 T $$Nb_{3}Sn$$ dipole suitable for installation in the LHC. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been fabricated and tested at FNAL in 2012-2014. The two 1 m long collared coils were then assembled into the first twin-aperture $$Nb_{3}Sn$$ demonstrator dipole and tested. Test results of this twin-aperture $$Nb_{3}Sn$$ dipole model are reported and discussed. | The high-luminosity large hadron collider (LHC) project at CERN entered into the production phase in October 2015 after the completion of the design study phase. In the meantime, the development of the 11 T dipole needed for the upgrade of the collimation system of the machine made significant progress with very good performance of the first two-in-one magnet model of 2-m length made at CERN. The 11 T dipole, which is more powerful than the current main dipoles of LHC, can be made shorter with an equivalent integrated field. This will allow creating space for the installation of additional collimators in specific locations of the dispersion suppressor regions. Following tests carried out during heavy ions runs of LHC in the end of 2015, and a more recent review of the project budget, the installation plan for the 11 T dipole was revised. Consequently, one 11 T dipole full assembly containing two 11 T dipoles of 5.5-m length will be installed on either side of interaction point 7. These two units shall be installed during the long shutdown 2 in years 2019-2020. After a brief reminder on the design features of the magnet, this paper describes the current status of the development activities, in particular the short model programme and the construction of the first full scale prototype at CERN. Critical operations such as the reaction treatment and the coil impregnation are discussed, the quench performance tests results of the two-in-one model are reviewed and finally, the plan toward the production for the long shut down 2 is 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 | 4,247 |
We propose to generate an ultra-high magnetic field greater than 10 MG on the basis of a z-pinch liner powered with a fast disk flux compression generator (DFCG) and a MC-I generator. A mathematical model of the electromagnetic liner acceleration and the magnetic flux compression when DFCG current passes through the liner in z-pinch geometry is formulated. The DFCG was simulated magnetohydrodynamically as a variable inductance with set time dependence according to calculated and experimental results. Numerical simulations were made on the basis of a system of one-dimensional equations of MHD in Lagrange variables together with differential circuit equations for the DFCG and liner. DFCG and liner parameters were determined by calculations, allowing us to obtain a magnetic field greater than 10 MG in a cylindrical volume of 5-10 cm length and 3-5 mm radius. | A scheme of a device intended for amplification of an axial magnetic field by a system of solid-state cylindrical liners is described in this paper. A 1-D magnetohydrodynamic model used in this paper is stated briefly. Calculation results of ultrahigh magnetic-field generation using one-, two-, and three-stage liner systems are presented. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 4,248 |
In the work we present experimental results for AC losses and critical currents of biaxially aligned YBCO-123 coated conductors, with Hastelloy as a substrate material. The critical current density of the tapes was of the order of 4.10 9 A/m 2 at the liquid nitrogen temperature. Magnetization losses, in sinusoidally varying external AC fields directed perpendicular to the plane of the tapes, were measured using a standard Lock-in technique. The frequency of the magnetic field was in a range of 7-64 Hz. The losses in YBCO are pure hysteretic for amplitudes up to 40 mT. Magnetization losses in the tape when carrying DC transport current are also reported. From obtained experimental data of dynamic resistance and the magnetization losses the total losses dissipated in the tape have been evaluated and compared with the critical state model predictions. | For example in some supercondcuting generators, motors and power transmission cables the superconductor experiences a changing magnetic field in a DC background. Simulating the losses caused by this AC ripple field is an important task from the application design point of view. In this work, we compare two formulations, the $H$-formulation and the minimum magnetic energy variation (the MMEV-formulation), based on the eddy current model (ECM) and the critical state model (CSM), respectively, in simulating ripple field losses in a DC biased coated conductor tape. Furthermore, we compare our simulation results with measurements. We investigate the frequency-dependence of the hysteresis loss predictions of the power law based ECM and verify by a measurement, that in DC use, ECM clearly over-estimates the homogenization of the current density profile in the coated conductor tape: the relaxation of the local current density is not nearly as prominent in the measurement as it is in the simulation. Hence, we suggest that the power law resistivity, used as the \emph{local} relation between the electric field intensity ${\bf E}$ and current density ${\bf J}$ in ECM, is not an intrinsic property of high-temperature superconductors. The difference between the models manifests itself as discrepancies in ripple field loss simulations in very low AC fields with significant DC fields or currents involved. The results also show, however, that for many practical situations, CSM and ECM are both eligible models for ripple field loss simulations. | Efficient laser-diode pumped Cr, Yb:YAG self-Q-switched laser by bonding Yb:YAG crystal to enhance inversion population have been demonstrated for the first time. Average output power of 1 W and optical-to-optical efficiency of 18.5% have been achieved. | eng_Latn | 4,249 |
The magnetic design of a ten-period (each period 14 mm) prototype superconducting undulator is reported using RADIA. The results of modelling the magnetic flux density are presented in an analytical formula. The dependence of the field integrals and phase error on the current density and undulator gap has been calculated, and temperature curves are determined for the models and are compared with earlier reported Moser-Rossmanith fits. | In this paper, we study the magnetic field measurement of U20 undulator. The U20 is a prototype hybrid structure of NdFeB magnets and cobalt steel poles. The hybrid device is made up of 25 periods with a period length of 20-mm each and is designed to deliver magnetic flux density (in rms) from 2400G to 500G in the 10–20-mm gap range. The validity of the theoretical and analytical formulas is analyzed through the measured field and phase integrals. | 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 | 4,250 |
Internal transport barriers (ITBs) can provide high tokamak confinement at modest plasma current. This is desirable for operation with most of the current driven non-inductively by the bootstrap mechanism, as currently envisaged for steady-state power plants. Maintaining such plasmas in steady conditions with high plasma purity is challenging, however, due to MHD instabilities and impurity transport effects. Significant progress has been made in the control of ITB plasmas: the pressure profile has been varied using the barrier location; q-profile modification has been achieved with non-inductive current drive, and means have been found to affect density peaking and impurity accumulation. All these features are, to some extent, interdependent and must be integrated self-consistently to demonstrate a sound basis for extrapolation to future devices. | The control of the toroidal current density spatial profile in tokamak plasmas will be absolutely critical in future commercial-grade reactors to enable high fusion gain, non-inductive sustainment of the plasma current for steady-state operation, and magnetohydrodynamic (MHD) instability-free performance. The evolution in time of the current profile is related to the evolution of the poloidal magnetic flux, which is modeled in normalized cylindrical coordinates using a partial differential equation (PDE) usually referred to as the magnetic flux diffusion equation. The control objective during the ramp-up phase is to drive an arbitrary initial profile to approximately match, in a short time windows during the early flattop phase, a predefined target profile that will be maintained during the subsequent phases of the discharge. Thus, such a matching problem can be treated as an optimal control problem for a PDE system. A distinctive characteristic of the current profile control problem in tokamaks is that it admits interior, boundary and diffusivity actuation. A receding-horizon control scheme is proposed in this work to exploit this unique characteristic and to solve the associated open-loop finite-time optimal control problem using different optimization techniques. The efficiency of the proposed scheme is shown in simulations. | The Korean mobile telecommunication services industry is entering a new transition period. This has been brought about by the market for mobile telecommunications reaching maturity, the launching of the IMT-2000 service and the scheduled introduction of mobile number portability. In response, the industry is shifting its strategic focus away from attracting new customers, towards retaining existing customers through the promotion of customer loyalty. This paper investigates how customer satisfaction and the switching barrier influence customer loyalty. The adjustment effect of the switching barrier on customer satisfaction and customer loyalty is also analysed. | eng_Latn | 4,251 |
A numerical simulation that is cylindrical in configuration space and 3-D (v/sub x/, v/sub y/, v/sub z/) in velocity space has been initiated to test a model for the near-wake dynamics of a very negatively charged body, with reference to the plasma environment around spacecraft. The simulation parameters were closely matched to those of a laboratory experiment so that the results may be compared directly. It was found from the laboratory study that the electrons and ions can display different temporal features in the filling-in of the wake; and that they both can be found in the very near-wake region (within one body diameter) of an object with a highly negative body potential. It was also found that the temperature of the electrons in the very near wake could be somewhat colder than the ambient value, suggesting the possibility of a filtering mechanism being operative there. The simulation results to date largely corroborate the density findings in terms of the presence of an enhancement for both ions and electrons and in its location. > | 3D-PIC (Particle In Cell) simulations were performed to emulate the dynamics and collection of plasma particles onto the surface of the UWE-IV, a satellite of miniaturized dimensions (CubeSat) launched in 2018. We review the electrostatic potential, currents collected and plasma disturbances of the CubeSat and characterize them by numerical simulation over Low Earth Orbits (LEO), in two general cases: as a passive satellite and with active thrusters without regard of neutralization units. During one orbital period the passive CubeSat drives an isotropic impingement of plasma electrons, that (because their higher mobility regarding ions) govern a negative surface potential. However, by the time-evolution of the charge sheath, we relate that potential barriers may be forming around the satellite that can reduce the collection of electrons over spacecraft surfaces. When thrusters are fired, spacecraft becomes more negatively charged than for a passive satellite, and their potential energy Esc is about hundreds of times larger than the ambient ion flowing energies, Ei. In this case, ion density maps of ambient oxygen (O+), show particles fill in the ion void (wake) zone due to bare electrostatic attraction by a (growing) negative satellite potential. The experiment was repeated in different orbit altitudes with varying plasma densities, showing that in space zones with greater concentration of plasma ions, the satellite potential is less negative, ultimately linked to this near-wake ion-focusing collection. Thus, we conclude that if thrusters operate in LEO altitudes, where the relatively higher plasma concentrations are (equatorial orbits of 300–500 km), large negative potentials can be avoided due to the natural rule of ambient ion dynamics. This study can be important for operations of future miniaturized satellites using this type of thruster technologie. | Oscillatory modes of swimming are used by a majority of aquatic swimmers to generate thrust. This work seeks to understand the phenomenological relationship between the body and caudal fin for fast and efficient thunniform swimming. Phase-averaged velocity data was collected and analyzed in order to understand the effects of body-fin kinematics on the wake behind a two degree-of-freedom fish model. The model is based on the yellowfin tuna (Thunnus albacares) which is known to be both fast and efficient. Velocity data was obtained along the side of the tail and caudal fin region as well as in the wake downstream of the caudal fin. Body-generated vortices were found to be small and have an insignificant effect on the caudal fin wake. The evolution of leading edge vortices formed on the caudal fin varied depending on the body-fin kinematics. The circulation produced at the trailing edge during each half-cycle was found to be relatively insensitive to the freestream velocity, but also varied with body-fin kinematics. Overall, the generation of vorticity in the wake was found to dependent on the trailing edge motion profile and velocity. Even relatively minor deviations from the commonly used model of sinusoidal motion is shown to change the strength and organization of coherent structures in the wake, which have been shown in the literature to be related to performance metrics such as thrust and efficiency. | eng_Latn | 4,252 |
[1] Measurements from the Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft during 40 orbits about Mercury are used to characterize the plasma depletion layer just exterior to the planet's dayside magnetopause. A plasma depletion layer forms at Mercury as a result of piled-up magnetic flux that is draped around the magnetosphere. The low average upstream Alfvenic Mach number (MA ~3–5) in the solar wind at Mercury often results in large-scale plasma depletion in the magnetosheath between the subsolar magnetopause and the bow shock. Flux pileup is observed to occur downstream under both quasi-perpendicular and quasi-parallel shock geometries for all orientations of the interplanetary magnetic field (IMF). Furthermore, little to no plasma depletion is seen during some periods with stable northward IMF. The consistently low value of plasma β, the ratio of plasma pressure to magnetic pressure, at the magnetopause associated with the low average upstream MA is believed to be the cause for the high average reconnection rate at Mercury, reported to be nearly 3 times that observed at Earth. Finally, a characteristic depletion length outward from the subsolar magnetopause of ~300 km is found for Mercury. This value scales among planetary bodies as the average standoff distance of the magnetopause. | [1] The Magnetic Pileup Boundary (MPB) is a sharp and permanent plasma boundary located between the bow shock and the ionospheric boundary, reported so far at Mars and comets. We use Mars Global Surveyor Magnetometer data to do a quantitative analysis of the magnetic field geometry in the surroundings of the Martian MPB. As a result, we report for the first time a dramatic enhancement of the magnetic field draping at this boundary. This new feature, already reported at comets, is independent of the presence of the crustal magnetic sources. Comparisons with similar results across the Martian and cometary magnetotails reveal that the MPB and the magnetotail boundary are connected. Moreover, the study of this feature can help understand the physics of the Venusian magnetic barrier. | 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 | 4,253 |
The electrical potential of plasma generated from an atmospheric plasma jet device with Ar or He gas is measured with a high voltage probe in a plasma column inside a tube as well as in the plasma ejected through the open end of the tube. When the double plasma jet devices with Ar-gas are operated by the opposite polarities of an ac voltage with a few kV at both ends of a glass tube, the electrical potential of plasma column is high at both ends of the column, while the electrical potential in the middle of the plasma column is a few tens of volts. When the plasma column is formulated with the double plasma jets of a high voltage electrode at one end of the glass tube and a grounded electrode at the other end of the tube, the plasma column potential decreases linearly from a high voltage to a very low value, as the measurement position moves from the side of high voltage to the grounded location. In the double plasma jets of He-gas operated by high voltages in opposite polarities, the ejected plasma jets ... | The current–voltage characteristics of atmospheric pressure plasma jets with various working gases (He, Ne, Ar, N2, and air) are investigated. Systems of the plasma jets are composed of a syringe needle inserted into a glass tube and are operated by a sinusoidal high-voltage through a dc–ac inverter generating several tens of kilohertz. The various electrode structures with or without the ground electrode are analyzed by using an equivalent circuit model. For the biomedical applications concerning the discharge stability and the electric safety with a low plasma-current and a low voltage operation, the suitable structures of plasma jets for each gas are suggested. For the plasma jets of inert gases (He, Ne, and Ar), the discharge triggered by an external ground electrode seems to be suitable, because the low current of a plasma plume is adjusted readily with a low voltage of 1–2 kV. For the jets of N2 and air, the nozzle of a metal ground electrode at the end of a glass tube is suggested to reduce the operation voltage below 3 kV and to acquire a low plume-current of a few milliamperes exiting the metal nozzle. | 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 | 4,254 |
An assessment of the trade-offs between total electrical energy, the pulse shape which is delivered to the gun and the chemical energy is presented for a future medium/large calibre (circa 130 mm) electrothermal-chemical (ETC) indirect fire gun system. In particular, this paper discusses the implications on total gun system volume i.e. including the electrical power supply and pulse conditioning system. The study considered electrical requirements of up to 25 MJ per shot. The potential performance improvements, compared with a similar sized chemical gun system, are also presented. The FNGUN finite difference based internal ballistics code has been used to simulate the likely trade-offs between electrical input energy, chemical energy and gun performance. This has shown that there is a dependence of the overall system performance on such parameters as: the anticipated electrical behaviour of the plasma; the shape of the electrical pulse supplied to the gun; and the internal ballistics of the gun. In particular it has been found that there is potentially a practical limit to the extent of pulse forming which is worth carrying out before parasitic losses in the pulse conditioning system become too great. Consequently, it is concluded that while some pulse shaping is necessary to meet the requirements of the internal ballistics, i,e, power increasing with time, there is little benefit from further optimisation of the pulse shape. > | Summary form only given. In this paper, a new method for current pulse shape conditioning is presented by taking a two-phase, 4 poles, slotless and iron-based passive compulsator (PCPA) as an example. The method is based on changing the number of turns of two-phase windings placed orthogonally while the number of conductors per pole is kept fixed. A conventional electrothermal chemical gun system (ETC) is simulated using this machine as power supply. The simulation results indicate that it is feasible to provide pulse-shaping flexibility compared with a two-phase PCPA, whose two-phase windings are also placed orthogonally with the equal number of turns. The machine is suitable for use as the power supply for conventional ETC. | 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 | 4,255 |
A version of extended magnetohydrodynamics (MHD) that incorporates electron inertia is obtained by constructing an action principle. Unlike MHD which freezes in magnetic flux, the present theory freezes in an alternative flux related to the electron canonical momentum. The associated Hamiltonian formulation is derived and reduced models that have previously been used to describe collisionless reconnection are obtained. | Recently, an extended version of magnetohydrodynamics that incorporates electron inertia, dubbed inertial magnetohydrodynamics, has been proposed [Lingam et al., Phys. Lett. A, 379, 570–576 (2015)]. This model features a noncanonical Hamiltonian formulation with a number of conserved quantities, including the total energy and modified versions of magnetic and cross helicity. In this work, a variational integrator is presented which preserves these conservation laws to machine accuracy. As long as effects due to finite electron mass are neglected, the scheme preserves the magnetic field line topology so that unphysical reconnection is absent. Only when the effects of finite electron mass are added, magnetic reconnection takes place. The excellent conservation properties of the method are illustrated by numerical examples in 2D. | This textbook provides a modern and accessible introduction to magnetohydrodynamics (MHD). It describes the two main applications of plasma physics – laboratory research on thermonuclear fusion energy, and plasma-astrophysics of the solar system, stars and accretion discs – from the single viewpoint of MHD. This approach provides effective methods and insights for the interpretation of plasma phenomena on virtually all scales, from the laboratory to the Universe. It equips the reader with the necessary tools to understand the complexities of plasma dynamics in extended magnetic structures. The classical MHDmodel is developed in detail without omitting steps in the derivations, and problems are included at the end of each chapter. This text is ideal for senior-level undergraduate and graduate courses in plasma physics and astrophysics. | eng_Latn | 4,256 |
Aims. We perform a three-dimensional (3D) high resolution numerical simulation in isothermal magnetohydrodynamics to study the magnetic reconnection process in a current sheet (CS) formed during an eruption of a twisted magnetic flux rope (MFR). Because the twist distribution violates the Kruskal-Shafranov condition, the kink instability occurs, and the MFR is distorted. The centre part of the MFR loses its equilibrium and erupts upward, which leads to the formation of a 3D CS underneath it. Methods. In order to study the magnetic reconnection inside the CS in detail, mesh refinement has been used to reduce the numerical diffusion and we estimate a Lundquist number S = 10 4 in the vicinity of the CS. Results. The refined mesh allows us to resolve fine structures inside the 3D CS: a bifurcating sheet structure signaling the 3D generalization of Petschek slow shocks, some distorted-cylindrical substructures due to the tearing mode instabilities, and two turbulence regions near the upper and the lower tips of the CS. The topological characteristics of the MFR depend sensitively on the observer’s viewing angle: it presents as a sigmoid structure, an outwardly expanding MFR with helical distortion, or a flare-CS-coronal mass ejection symbiosis as in 2D flux-rope models when observed from the top, the front, or the side. | We describe a partial filament eruption on 11 December 2011 that demonstrates that the inclusion of mass is an important next step for understanding solar eruptions. Observations from the Solar Terrestrial Relations Observatory-Behind (STEREO-B) and the Solar Dynamics Observatory (SDO) spacecraft were used to remove line-of-sight projection effects in filament motion and correlate the effect of plasma dynamics with the evolution of the filament height. Flux cancellation and nearby flux emergence are shown to have played a role in increasing the height of the filament prior to eruption. The two viewpoints allow the quantitative estimation of a large mass-unloading, the subsequent radial expansion, and the eruption of the filament to be investigated. A 1.8 to 4.1 lower-limit ratio between gravitational and magnetic-tension forces was found. We therefore conclude that following the loss-of-equilibrium of the flux-rope, the radial expansion of the flux-rope was restrained by the filamentary material until 70% of the mass had evacuated the structure through mass-unloading. ::: ::: ::: Electronic Supplementary Material ::: The online version of this article (10.1007/s11207-017-1224-y) contains supplementary material, which is available to authorised users. | We present the case of a 50-year-old man who developed a delayed progressive swelling over the medial aspect of his right thigh, six weeks following minimally invasive plate osteosynthesis (MIPO) of a supracondylar femur fracture. Angiography showed a false aneurysm of the superficial femoral artery, caused by progressive displacement of a butterfly fragment. Open vascular repair was performed and the sharp edge of the butterfly fragment was removed. | eng_Latn | 4,257 |
[1] We propose a quasi-steady nonlinear circuit model for the solar wind-magnetosphere-ionosphere (SW-M-I) coupling to study the observed saturation of polar cap potential. The oval conductance is shown to be a nonlinear circuit element since it increases with increasing dayside reconnection E field driving the proposed circuit. Oval conductance is produced by precipitating particles energized by enhanced sunward convection in the plasma sheet driven by reconnection at the dayside magnetopause and in the plasma sheet. The asymptotic saturation potential is shown to increase with (1) decreasing internal resistance of the dynamo region, (2) increasing length of dayside reconnection line, (3) increasing ratio of nightside to dayside reconnection potentials, and (4) increasing ratio of nightside to dayside internal resistances. | [1] Cross polar cap voltage saturation has been observed by various measurement techniques. An example of the saturation is shown in this paper and an explanation is proposed in terms of magnetospheric current behavior. The cross cap voltage saturation might be associated with either a voltage source or a current source effect since the cross cap potential and cross cap current are related by Ohm's law. The cross cap current is the difference between the Region 1 current influx to the polar cap boundary and the Region 2 current. Because, during high interplanetary magnetic field (IMF) −Bz conditions, the Region 2 current is significantly enhanced, the cross cap current, and hence cross cap voltage, is not anomalously higher than usual. Our measurements show agreement with Region 2 (partial ring current) enhancement during high IMF −Bz conditions. | 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 | 4,258 |
Stability of efficient operation at one of the high-order modes is of great importance for the development of megawatt-level gyrotrons intended for plasma experiments in controlled fusion reactors. Typically such gyrotrons operate at modes with large azimuthal indices, which form a rather dense spectrum of eigenfrequencies. Therefore, instead of considering interaction of electrons with a large number of such modes it is more convenient to analyze the spatial-temporal evolution of an envelope formed by a superposition of these modes with the electrons. In all previous studies of stability of such envelopes it was assumed that some kind of azimuthal nonuniformity is present in the initial condition for the wave envelope. However, the physical reason for this nonuniformity, which is apparently the nonuniformity of the electron emission, was not analyzed. In the present paper, the relation between the emission nonuniformity and resulting nonuniformity of the wave envelope is established. Then, results of num... | In this paper, the design studies of a triple frequency (170/204/236GHz) coaxial cavity gyrotron are carried out which is suitable for plasma heating application in a commercial fusion demonstration (DEMO) tokamak class prototype reactor. To reduce the spatial and maintenance requirements in the heating system of the DEMO tokamak, the output power of the proposed gyrotron is targeted at $\approx 3$ MW for all the three operating frequencies. The cavity modes are selected by considering various physical and technical constraints of the multifrequency gyrotron. The dimensions of the interaction cavity are optimized for the chosen modes at the desired frequencies through cold-cavity calculations. Mode competition studies are then performed to understand the effect of the parasitic modes on the desired modes around the operating frequencies. A triangular corrugated coaxial insert is considered for reducing the problem of localized heating. Initial optimization of beam parameters and magnetic field is carried out using single-mode calculations for the maximum output efficiency. A triode-type coaxial magnetron injection gun is designed for supporting this multifrequency operation. Startup calculations are carried out with beam space-charge neutralization at all the three operating frequencies. These studies predict that a 3-MW, continuous-wave operation is possible at the desired frequencies of the proposed DEMO class gyrotron. | 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 | 4,259 |
The results on time-dependent 2-D fluid modeling of edge plasmas with non-diffusive intermittent transport across the magnetic field (termed cross-field) based on the novel macro-blob approach are presented. The capability of this approach to simulate the long temporal evolution (∼0.1 s) of the background plasma and simultaneously the fast spatiotemporal dynamics of blobs (∼10−4 s) is demonstrated. An analysis of a periodic sequence of many macro-blobs (PSMB) is given showing that the resulting plasma attains a dynamic equilibrium. Plasma properties in the dynamic equilibrium are discussed. In PSMB modeling, the effect of macro-blob generation frequency on edge plasma parameters is studied. Comparison between PSMB modeling and experimental profile data is given. The calculations are performed for the same plasma discharge using two different models for anomalous cross-field transport: time-average convection and PSMB. Parametric analysis of edge plasma variation with transport coefficients in these models... | A simplified model describing turbulent plasma transport in the far scrape-off layer has been proposed for calculation of the plasma heat and particle fluxes to the first wall (FW) of the DEMO tokamak. The model has been implemented in the TOKES code for simulation of the heat flux distribution along the tokamak FW. First simulations of the wall heat flux, using this model, predict more pronounced “hot spots” at the top of the DEMO wall in comparison with the exponential heat flux decay model, commonly used for simulation of the flux. | Perfect Quantum Cloning Machines (QCM) would allow to use quantum nonlocality for arbitrary fast signaling. However perfect QCM cannot exist. We derive a bound on the fidelity of QCM compatible with the no-signaling constraint. This bound equals the fidelity of the Bu\v{z}ek-Hillery QCM. | eng_Latn | 4,260 |
High-field accelerator magnets of the next generation will require coil grading in order to decrease the amount of superconductor and hence the magnet cost. The joints between Nb ::: 3 ::: Sn conductor grades must have low electrical resistance (<;1 nΩ) and reasonably good mechanical strength. The joints are classified as “Wind & React” because they will be assembled during the coil winding, prior to the heat treatment. Various techniques have been initially considered for the preparation of joints between Nb ::: 3 ::: Sn Rutherford cables, including soldering, diffusion bonding with and without interleaved copper foil, electroplated cables (to “smooth” the surface of the cable overlap), and crimped cables. Initial investigations included examinations of cross-sections (cut by electro-erosion). In a second stage, joint samples are prepared and assembled for test in the SULTAN test facility, with background field up to 11 T and operating current up to 14 kA. Besides the resistance test results, the selection of the most promising joint layout will also consider the restriction imposed by the coil manufacturing, e.g., available space for assembly, access after heat treatment, applicable quality control, etc. | The German SUpraLeiterTest ANlage (SULTAN) test facility at the Centre de Recherches en Physique des Plasma (CRPP), Villigen, is a worldwide unique tool to test high current superconductors over a broad range of operating conditions. The key component of the facility is a set of forced flow superconducting coils to generate a background field up to 11 T. A flux pump supplies the test sample with current up to 100 kA. A set of pulsed coils generates a transverse, time varying field, with amplitude up to 4 T and field rate up to 65 T/s. The instrumentation and the data acquisition system allow accurate measurements of the dc behavior, ac losses, transient stability, current distribution. A clear definition of the interface between facility and users gives flexible and easy access to external scientists with minimum time requirement for sample replacement. The experiments from the last five years of operation contributed to the progress in understanding design issues for large cable-in-conduit conductors, including quench propagation, copper segregation, coupling loss, joint, stability, and cyclic load. | 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 | 4,261 |
The ATLAS detector is one of the huge detectors used on the future LHC at CERN. Its magnet system is composed of a barrel toroid (BT) and two end-cap toroids (ECT) inserted at the ends of the BT, of an inner solenoid and of an iron shield close to the inner bore of the BT. The coil cryogenic system is designed to cool down the thermal shields by helium gas at 80 K. In the event of any variation of the magnetic flux, eddy currents are induced in these shields. This paper presents the computations of eddy currents in the shields using a variational formulation of the problem in terms of the electric vector potential and a finite element method. The worst case - fast discharge into dump diodes and resistors - is presented in the electrical behavior section. The evolution of eddy currents is computed using this method. Finally, anchor points are determined in the mechanical analysis in order to minimize the mechanical stresses on the shields. | This paper deals with the calculation of the eddy currents in the structures of a Tokamak, which can be assimilated to thin conductors, so that the three-dimensional problem can be reduced mathematically to a two-dimensional one, the variables being two orthogonal coordinates of the considered surface. A variational formulation of the problem in terms of the electric vector potential is then given and a finite element method has been used, which enables to treat the complicated geometry of the toroidal field magnet, the mechanical structures and the vacuum vessels of Tore Supra. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 4,262 |
An extremely simple arc discharge unit for producing high-energy carbon plasma ions for the deposition of the adhesion layer of high-quality diamond-like carbon (DLC) coatings is presented. The system contains only a simplistic anode–cathode arrangement and the anode–cathode and ignition circuits. The high-ion energies result from high current rise rates of the short arc discharge pulses. In our current system a sufficient rise rate (5·10 9 A/s) is achieved with 6 kV anode–cathode voltages. However, much lower voltages can be used if low inductance circuits are used. The presented arc discharge set-up has no particle filtering system. The number of particles in a sufficiently thick adhesion layer was 40/mm 2 , which is acceptable for most applications. | The current status of diamond-like carbon (DLC) coatings for biomedical applications is reviewed with emphasis on load-bearing coatings. Although diamond-like carbon coating materials have been studied for decades, no indisputably successful commercial biomedical applications for high load situations exist today. High internal stress, leading to insufficient adhesion of thick coatings, is the evident reason behind this delay of the break-through of DLC coatings for applications. Excellent adhesion of thick DLC coatings is of utmost importance for load-bearing applications. According to this review superior candidate material for articulating implants is thick and adherent DLC on both sliding surfaces. With the filtered pulsed arc discharge method, all the necessary requirements for the deposition of thick and adherent DLC are fulfilled, provided that the substrate material is selected properly. | Several researchers have measured ions leaving ion thruster discharge chambers with energies far greater than measured discharge chamber potentials. Presented in this paper is a new mechanism for the generation of high energy ions and a comparison with measured ion spectra. The source of high energy ions has been a puzzle because they not only have energies in excess of measured steady state potentials, but as reported by Goebel et. al. [1], their flux is independent of the amplitude of time dependent plasma fluctuations. The mechanism relies on the charge exchange neutralization of xenon ions accelerated radially into the potential trough in front of the discharge cathode. Previous researchers [2] have identified the importance of charge exchange in this region as a mechanism for protecting discharge cathode surfaces from ion bombardment. This paper is the first to identify how charge exchange in this region can lead to ion energy enhancement. | eng_Latn | 4,263 |
We analyse the changes in the partial polarization of random, stationary light fields in transmission through a near-field probe. The probe is modelled as a two-dimensional metal-coated optical fibre tip through which the field is propagated by applying the boundary-integral method. Both the magnitude of the opening angle and the aperture size of the probe are found to significantly influence the partial polarization of the field. We discuss the results in terms of both the conventional two-dimensional and the recent three-dimensional formalism for the degree of polarization. | L Ramdas Ram-Mohan Oxford: Oxford University Press (2002) £26.50 (paperback), ISBN 0-19-852522-2 Although this book is one of the Oxford Texts in Applied and Engineering Mathematics, we may think of it as a physics book. It explains how to solve the problem of quantum mechanics using the finite element method (FEM) and the boundary element method (BEM). Many examples analysing actual problems are also shown. As for the ratio of the number of pages of FEM and BEM, the former occupies about 80%. This is, however, reasonable reflecting the flexibility of FEM. Although many explanations of FEM and BEM exist, most are written using special mathematical expressions and numerical computation fields. However, this book is written in the `language of physicists' throughout. I think that it is very readable and easy to understand for physicists. In the derivation of FEM and the argument on calculation accuracy, the action integral and a variation principle are used consistently. In the numerical computation of matrices, such as simultaneous equations and eigen value problems, a description of important points is also fully given. Moreover, the practical problems which become important in the electron device design field and the condensed matter physics field are dealt with as example computations, so that this book is very practical and applicable. It is characteristic and interesting that FEM is applied to solve the Schrodinger and Poisson equations consistently, and to the solution of the Ginzburg--Landau equation in superconductivity. BEM is applied to treat electric field enhancements due to surface plasmon excitations at metallic surfaces. A number of references are cited at the end of all the chapters, and this is very helpful. The description of quantum mechanics is also made appropriately and the actual application of quantum mechanics in condensed matter physics can also be surveyed. In the appendices, the mathematical foundation, such as numerical quadrature formulae and Green's functions, is conveniently described. I recommend this book to those who need to solve Schrodinger equations, especially within a system of complicated shape. | The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) is making and testing 20 insertion region dipoles for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets have the same coil design as the arc dipoles now operating in the Relativistic Heavy Ion Collider (RHIC) at BNL and will be of single and twin aperture cold mass configurations. They will produce fields up to 4.14 T for operation at 7.56 TeV. The magnets will be tested at 4.5 K using either forced flow supercritical helium or liquid helium. This paper reports the results of tests of four D1 magnets, including spontaneous quench performance, verification of quench protection heater operation, and magnetic field quality. | eng_Latn | 4,264 |
The Sun is a magnetic star whose magnetism and cyclic activity is linked to the existence of an internal dynamo. We aim to understand the establishment of the solar magnetic 22-yr cycle, its associated butterfly diagram and field parity selection through numerical simulations of the solar global dynamo. Inspired by recent observations and 3D simulations that both exhibit multicellular flows in the solar convection zone, we seek to characterise the influence of various profiles of circulation on the behaviour of solar mean-field dynamo models. We are using 2-D mean field flux transport Babcock-Leighton numerical models in which we test several types of meridional flows: 1 large single cell, 2 cells in radius and 4 cells per hemisphere. We confirm that adding cells in latitude tends to speed up the dynamo cycle whereas adding cells in radius more than triples the period. We find that the cycle period in the four cells model is less sensitive to the flow speed than in the other simpler meridional circulation profiles studied. Moreover, our studies show that adding cells in radius or in latitude seems to favour the parity switching to a quadrupolar solution. According to our numerical models, the observed 22-yr cycle and dipolar parity is easily reproduced by models including multicellular meridional flows. On the contrary, the resulting butterfly diagram and phase relationship between the toroidal and poloidal fields are affected to a point where it is unlikely that such multicellular meridional flows persist for a long period of time inside the Sun, without having to reconsider the model itself. | We want to study the connections between the magnetic field generated inside the Sun and the solar wind impacting Earth, especially the influence of north-south asymmetry on the magnetic and velocity fields. We study a solar-like 11-year cycle in a quasi-static way: an asymmetric dynamo field is generated through a 2.5-dimensional (2.5-D) flux-transport model with the Babcock-Leighton mechanism, and then is used as bottom boundary condition for compressible 2.5-D simulations of the solar wind. We recover solar values for the mass loss rate, the spin-down time scale and the Alfv\'en radius, and are able to reproduce the observed delay in latitudinal variations of the wind and the general wind structure observed for the Sun. We show that the phase lag between the energy of the dipole component and the total surface magnetic energy has a strong influence on the amplitude of the variations of global quantities. We show in particular that the magnetic torque variations can be linked to topological variations during a magnetic cycle, while variations in the mass loss rate appear to be driven by variations of the magnetic energy. | Obesity and metabolic syndrome (MetS) are serious and growing health care problems worldwide, leading an increased risk for type 2 diabetes (T2D) and cardiovascular disease (CVD). Over the past decade, emerging evidence has shown that an increased chromosomal damage, as determined by the cytokinesis-block micronucleus (CBMN) assay, is correlated to the pathogenesis of metabolic and CVD. An increased micronuclei (MN) frequency has been demonstrated in peripheral blood lymphocytes of patients with polycystic ovary syndrome, a common condition in reproductive-aged women associated with impaired glucose tolerance, T2D mellitus and the MetS. High levels of MN have been detected to be significantly correlated with T2D as well as with the occurrence and the severity of coronary artery disease (CAD). Long-term follow-up studies have shown that an increased MN frequency is a predictive biomarker of cardiovascular mortality within a population of healthy subjects as well as of major adverse cardiovascular events in patients with known CAD. Overall, these findings support the hypothesis that CBMN assay may provide an useful tool for screening of the MetS and its progression to diabetes and CVD in adults as well in children. Large population-based cohorts are needed in order to compare the MN frequencies as well as to better define whether MN is a biomarker or a mediator of cardiometabolic diseases. | eng_Latn | 4,265 |
Detailed stability studies are made with new diagnostics in the FRX‐C/LSM field‐reversed theta pinch [Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Vienna, 1989), Vol. II, p. 517]. These studies seek the origin of a degradation of the confinement properties of field‐reversed configurations (FRC’s) that appears associated with strong axial dynamics during plasma formation. Several instabilities are observed, including rotational modes, interchanges, and tilt instabilities. Only the latter are strongly correlated with FRC confinement. Tilt instabilities are observed for FRC’s with larger average number of ion gyroradii (s∼3–5) and smaller separatrix elongations (e∼3–4). Coincidently, strong axial dynamics occurs for cases with larger s and smaller e values, through increases in either reversed bias field or fill pressure. These data provide some understanding of FRC stability. In agreement with finite Larmor radius theory, there is a regime of gross stability for the very kinetic and elongate... | We describe a program to demonstrate the scientific basis of magnetized target fusion (MTF). MTF is a potentially low-cost path to fusion which is intermediate in plasma regime between magnetic (MFE) and inertial fusion energy (IFE). MTF involves the compression of a magnetized target plasma and pressure times volume (PdV) heating to fusion relevant conditions inside a converging flux conserving boundary. We have chosen to demonstrate MTF by using a field-reversed configuration (FRC) as our magnetized target plasma and an imploding metal liner for compression. These choices take advantage of significant past scientific and technical accomplishments in MFE and defense programs research and should yield substantial plasma performance (n/spl tau/>10/sup 13/ s-cm/sup -3/ T>5 keV) using an available pulsed-power implosion facility at modest cost. We have recently shown the density, temperature, and lifetime of this FRC to be within a factor of 2-3 of that required for use as a suitable target plasma for MTF compression for a fusion demonstration. | We characterize stability under composition, inversion, and solution of ordinary differential equations for ultradifferentiable classes, and prove that all these stability properties are equivalent. | eng_Latn | 4,266 |
Most formation models and numerical simulations cause a helical magnetic field to form, accelerate and collimate jets in active galactic nuclei (AGN). For this reason, observational direct evidence for the existence of these helical magnetic fields is of special relevance. In this work, we present ultra-high-resolution observations of the innermost regions of the jet in the quasar NRAO150. We study the polarization structure and report evidence of a helical magnetic field. | The presence of a helical magnetic field threading the jet of an Active Galactic Nucleus (AGN) should give rise to a gradient in the observed Faraday rotation measure (RM) across the jet, due to the associated systematic change in the line-of-sight magnetic field. Reports of observations of transverse RM gradients across AGN jets have appeared in the literature starting from 2002, but concerns were raised about the resolution required for these gradients to be reliable, and there was a lack of a full understanding of the best approach to accurate estimation of the uncertainties of local RM values. These questions have now been resolved by recent Monte Carlo simulations carried out by various groups, enabling both a verification of previously published results and reliable analyses of new data. We consider here RM gradients across the jet structures of 15 AGN, some previously published in the refereed literature but without a correct and complete error analysis, and some published for the first time here, all of which have monotonic transverse RM gradients with significances of at least 3 sigma. | We consider classical magnetic helicity (a Gauss invariant of magnetic lines) and higher helicity invariants as nonlinear constraints for dynamo action. We argue that the Gauss invariant has several properties absent from higher helicity invariants which prevents use of the latter to constrain dynamo action. We consider other helicities (hydrodynamic helicity and cross helicity) in the context of the dynamo problem. | eng_Latn | 4,267 |
In order to model the non-equilibrium plasma within the discharge region of a Hall thruster, the velocity distribution functions (VDFs) must be obtained accurately. A direct kinetic (DK) simulation method that directly solves the plasma Boltzmann equation can achieve better resolution of VDFs in comparison to particle simulations, such as the particle-in-cell (PIC) method that inherently include statistical noise. In this paper, a one-dimensional hybrid-DK simulation, which uses a DK simulation for heavy species and a fluid model for electrons, is developed and compared to a hybrid-PIC simulation. Time-averaged results obtained from the hybrid-DK simulation are in good agreement with hybrid-PIC results and experimental data. It is shown from a comparison of using a kinetic simulation and solving the continuity equation that modeling of the neutral atoms plays an important role for simulations of the Hall thruster discharge plasma. In addition, low and high frequency plasma oscillations are observed. Altho... | A 100 W radial scaled Hall Thruster has been designed and manufactured using as reference design the D-55 thruster with anode layer (TAL). The magnetic field required is provided by permanent magnets following a modular design in order to compare three different magnetic field configurations: A) nominal, B) orthogonal magnetic field and C) high magnetic field. In Hall Thrusters the magnetic field is used to confine the electrons and create highly ionized plasma. Configuration A and configuration B were chosen to compare two different topographies of the magnetic field with two different magnetic field gradients and to study their influence in the plasma discharge and thruster performance. Both configurations where derived assuming Bohm diffusion as the dominant process in the plasma discharge. If instead of Bohm diffusion it is considered electron-wall collisions as main mechanism in the electron transport then a higher magnetic field is required and in consequence configuration C was designed. These three configurations are intended to provide a better understanding of the influence of the magnetic field in the thruster discharge. | 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 | 4,268 |
The auroral current density-voltage and energy flux density-voltage relationships are derived under the assumption that magnetospheric electrons above the auroral acceleration region are described by the κ distribution function. To illustrate the effects of this boundary condition on auroral precipitation, a two-dimensional model of auroral electrodynamics similar to that of Lyons [1980] has been developed by imposing current continuity in a region of converging electric field in the auroral zone. The current carried by precipitating magnetospheric electrons inside auroral arcs connects to return current regions at the arc edges via ionospheric Pedersen currents. A key feature is the ability to parameterize the magnetospheric boundary electron population as either a κ or Maxwellian distribution. For equal density and temperature a κ = 5 boundary condition yields a parallel potential drop ∼ 5% larger and a precipitating energy flux structure ∼ 5% wider than those of its Maxwellian counterpart. More significant differences emerge between these two distributions when the density is held constant but the spectral shape of the distributions are allowed to differ. The κ distribution results predict up to double the peak auroral energy flux and as much as a 20-30% increase in the latitudinal width of the auroral energy flux as compared with the Maxwellian results. The width and intensity of the inverted V structures in the model results are found to be closely related to the level of thermal energy flux outside the inverted V. | We present two case studies of FAST electrostatic analyzer measurements of both highly nonthermal ($\kappa \lesssim$~2.5) and weakly nonthermal/thermal monoenergetic electron precipitation at $\sim$4000~km, from which we infer the properties of the magnetospheric source distributions via comparison of experimentally determined number density--, current density--, and energy flux--voltage relationships with corresponding theoretical relationships. We also discuss the properties of the two new theoretical number density--voltage relationships that we employ. Moment uncertainties, which are calculated analytically via application of the \citet{Gershman2015} moment uncertainty framework, are used in Monte Carlo simulations to infer ranges of magnetospheric source population densities, temperatures, $\kappa$ values, and altitudes. We identify the most likely ranges of source parameters by requiring that the range of $\kappa$ values inferred from fitting experimental moment-voltage relationships correspond to the range of $\kappa$ values inferred from directly fitting observed electron distributions with two-dimensional kappa distribution functions. Observations in the first case study, which are made over $\sim$78--79$^\circ$ invariant latitude (ILAT) in the Northern Hemisphere and 4.5--5.5 magnetic local time (MLT), are consistent with a magnetospheric source population density $n_m =$~0.7--0.8~cm$^{-3}$, source temperature $T_m \approx$~70~eV, source altitude $h =$~6.4--7.7~$R_E$, and $\kappa =$~2.2--2.8. Observations in the second case study, which are made over 76--79$^\circ$~ILAT in the Southern Hemisphere and $\sim$21~MLT, are consistent with a magnetospheric source population density $n_m =$~0.07--0.09~cm$^{-3}$, source temperature $T_m \approx$~95~eV, source altitude $h \gtrsim$~6~$R_E$, and $\kappa =$~2--6. | 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 | 4,269 |
The feeding of as many as four experimental areas from a single ZGS pulse calls for a flexible system for controlling the spill of the beam. The beam is displaced radially into as many as four targets plunged into position after radial damping of the beam has occurred. Beam spills have been adjusted in time duration from 5 microseconds to 500 milliseconds during a flat-top period of the main magnet cycle. Spills shorter than about 0.5 millisecond are accomplished by a pulsed magnetic bump which displaces the orbit center. Spills longer than about 0.2 milliseconds are accomplished by programmed adjustment of the accelerating rf so as to expand or contract the orbit radius. Radiation level monitors in the vicinity of the targets or in the experimental beam lines are used to feedback a signal into the rf program which results in the reduction of spill irregularities due to main magnet ripple and other noises. Such a spill has rf structure and is "on" from 25% to 50% of the time. The repeatability for placing the beam into a given position for targeting is about 0.01 inch without employing feedback from radiation level monitors. A description of the equipment and instrumentation is given along with the performance. | An energy discharge system has been constructed which permits repetitive pulses spaced 30 ms apart or greater to the Zero Gradient Synchrotron (ZGS) beam bumper magnet. To allow beam bumping to either side of the equilibrium orbit, each pulse is independent in polarity and magnitude. Two pulses per machine cycle are provided, but the system is being expanded to five. The system consists of the beam bumper magnet time-sharing two independent energy storage subsystems each containing two series ignitrons, one for each polarity and two crowbar ignitrons, one for each polarity. A logic system automatically triggers the crowbar associated with a given subsystem. An early crowbar trigger can be used which shunts the coil well before peak current occurs reducing the peak current on a given pulse. Each subsystem contains a 2 A, 14 kV power supply and 450 ?F of capacitance. The beam bumper magnet has a 4-turn coil which may be connected either in parallel or series. The inductance for one turn is 1.6 ?H. The beam may be targeted or extracted in less than 20 ?s or as long as several hundred ?s, depending on the choice of C and L. If exceptionally long times are needed, the subsystems may be interconnected causing all capacitors to be in parallel. | 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 | 4,270 |
The Tevatron magnets at Fermilab are cooled by a hybrid system which consists of a 5000 liters/hr central helium liquefier coupled with a small-diameter liquid transfer line connecting twenty-four satellite refrigerators. The transfer line supplies liquid helium for both the refrigerators and the magnet lead flow as well as liquid nitrogen for the magnet shields. The satellites act as amplifiers with a gain of twelve by using the enthalpy of the helium supplied by the central liquefier as liquid and converting it to 4.5-K refrigeration and then returning it as 300-K gas. This arrangement combines the advantages of a single central facility with those of individual stand-alone units stationed around the ring. The central liquefier has the high efficiency associated with large components but its requirements for distribution of both cryogenic liquids and electric power to the service buildings is reduced. The six compressor buildings supply 20 atm helium to the twenty-four refrigerators through a discharge header located on the berm and a suction header located in the tunnel. The compressor buildings each have four-two stage 58 g/sec screw compressors; each of these has its own oil removal system. The inventory in the ring is controlled at the first compressormore » building through a cross-connect line to the central liquefier. The suction header is also used as the cooldown line as well as for quench relief. A third header located in the tunnel is the nitrogen collection and relief header.« less | The Energy Saver Refrigeration System is based on the concept of a central helium liquefier (5000 l/hr) providing liquid to 24 satellite refrigerators (966 W at 4.6/degree/K), which operate as amplifiers with a gain of 12. This concept was tested, cooling two 125 m long strings of superconducting magnets. The test was run using one satellite refrigerator operating as the ''central liquefier'', shipping liquid helium through a 250 m long transfer line to a second satellite refrigerator, which in turn cooled the magnets. In addition to testing the satellite concept, the heat loads of the magnets and transfer line were also measured. 3 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 | 4,271 |
In this paper we examine theoretically the influence of density profile shape on the diocotron instability in a cylindrical, low-density (ωpe2≪ωce2) non-neutral electron plasma column confined radially by a uniform axial magnetic field B0ez. The analysis assumes electrostatic flute perturbations (∂/∂z=0) about an axisymmetric equilibrium density profile ne0(r), where r=(x2+y2)1/2 is the radial distance from the column axis. Two classes of density profiles with inverted population in radius r are considered. These are the following: (a) a step-function density profile with uniform density ne⋅Δ in the column interior 0⩽r<rb−, and uniform density ne in an outer annular region rb−<r<rb+; and (b) a continuously-varying density profile of the form ne0(r)=ne(Δ+r2/rb2)(1−r2/rb2)2 over the interval 0⩽r<rb. Here, ne, rb−, rb+ and rb are positive constants, and the dimensionless parameter Δ measures the degree of “hollowness” of the equilibrium density profile ne0(r). Detailed linear stability properties are cal... | We report on the physical mechanisms of development, coexistence and interaction of Pierce-Bursian and diocotron instabilities in the non-neutral relativistic electron beam (REB) in the classic vircator. The analytical and numerical analysis is provided by means of 3D electromagnetic simulation. We conducted an extensive study of characteristic regimes of REB dynamics determined by the instabilities development. As a result, a regime map has been obtained. It demonstrates sequential switching of the REB dynamics from the regime with N=1 to the regime with N = 7 electron bunches in the azimuth direction with the beam current growth for the different external magnetic fields. The numerical analysis of bunch equilibrium states has identified the physical causes responsible for the REB regime switchings. | We characterize stability under composition, inversion, and solution of ordinary differential equations for ultradifferentiable classes, and prove that all these stability properties are equivalent. | eng_Latn | 4,272 |
In electromagnetic launch (EML) applications, a compensated pulsed alternator is an effective form of pulsed power supply because of its high energy density and power density. The basic advantages of compensated pulsed alternators for EML applications are their higher energy density than capacitors and their export ac output that is suitable for transmission and transformation. In general, external excitation is adopted as a form of self-excitation or pulse excitation in compensated pulsed alternators with an iron core or air core. Using this form not only results in heavy and bulky components but also complicates and reduces the reliability of the system. This paper proposes a novel compensated pulsed alternator that is excited by permanent magnets (PMs) and equipped with an iron core or air-core stator. This system does not require any excitation converter or brush–slip ring, thereby making it more reliable, less massive, and less voluminous than the system with self-excitation or pulse excitation. In addition, analytical models are introduced to simulate the air-gap magnetic distribution, back-electromotive force, pulsed current wave, discharge torque, and energy exchange of this machine. A scale-model prototype of the PM-compensated pulsed alternator is designed, fabricated, and tested. The actual output voltage waveform and pulsed current waveform are sampled and compared with the predicted ones. The results show that the design of the PM compulsator is feasible and reliable. | Air-core pulsed alternators greatly enhance the power density capabilities of pulsed power supply for electromagnetic launchers. Compared with iron-core electric machines, they require very high-excitation currents. Usually, the self-excitation mode is adopted in these systems. However, the self-excitation mode is a positive feedback process that should be precisely controlled to avoid the system being destroyed. The excitation losses are very large during the process of establishing the large field current. To solve these problems, a new excitation mode, the pulse-excitation mode, is presented in this paper. The main idea is that a pulsed current charges the field coil so that the field coil and the armature coil conduct only for a short time around the main discharge pulse. This will avoid the machine being overheated and the risk of positive feedback process. Compared with the self-excitation mode, the pulsed alternator can be operated in a higher discharge frequency and the circuit schematic of the system is simpler. A larger field capacitor is used that charges the field coil to the desired current just by a pulse. As the energy density of pulse capacitor is enhanced rapidly, the volume and mass of the field capacitor are acceptable. The pulse-excitation mode is a combination of pulsed alternator and pulsed capacitor. In this paper, the characteristics of self-excitation and pulse-excitation are analyzed, respectively. The performances of both systems are simulated, and the main waveforms are presented. Finally, there is a practical comparison between them. | Attraction of lung macrophages to particle deposition sites has been demonstrated in different animal species. We reported a threefold increase of the number of macrophages to occur within 40 min after polystyrene particle deposition in hamster airways [Geiser et al. (1994) Am. J. Respir. Cell Mol. Biol. 160: 594–603]. Complement-derived chemotactic activity is one of the mechanisms postulated for macrophage recruitment. It was the aim of this study to test whether complement-derived chemotactic activity is involved in the rapid recruitment of macrophages to the site of deposited polystyrene particles in hamster airways. We first developed an in vitro cell migration assay for hamster macrophages to assess complement-derived chemotaxis. Second, the bronchoalveolar lavage fluids (BALF) of four hamsters that had inhaled aerosols of polystyrene microspheres were tested for chemotactic activity by this bioassay and compared with BALF of four sham-exposed hamsters. Chemotactic response of macrophages was found toward complement-activated hamster serum, whereas macrophage migration was not increased toward BALF of particle and sham-exposed hamsters. In contrast, macrophage migration to BALF of both groups was reduced by 1.6-fold. Thus, the stimulus for macrophage recruitment to the site of deposited polystyrene particles in hamster airways could not be demonstrated using this bioassay. | eng_Latn | 4,273 |
This paper presents a study of the magnetization AC loss characteristics of YBCO coated conductors arranged in vertical stacks, which is a common configuration in practical applications such as superconducting coils. The AC losses in applied external perpendicular field are investigated both experimentally and by means of finite-element method calculations. The numerical method is validated by comparison with experimental results, and is also used for calculation of the losses in cases for which our present experimental setup is not suitable due to physical constraints. It is shown that increasing the number of tapes in the stack leads to a decrease of the magnetization AC loss. The inter-tape spacing has been also varied in order to investigate its influence on the AC loss performance of the YBCO stacks. The calculated magnetic field and current density profiles are used to illustrate the loss differences in the various cases. | The AC loss measurements of the high temperature superconductor (HTS) cable prototype in the EDIPO test facility motivated detailed investigations of the loss contributions from the tape, strand and cable stages of the HTS fusion conductor design proposed at the Swiss Plasma Center. As an initial step of the task, magnetization tests of soldered stacks of HTS tapes were carried out at temperatures of 5 and 77 K and magnetic fields up to 12 T using the vibrating sample magnetometer technique. The influence on the magnetization loss of the number of tapes, width of the tape, field's orientation and tape's manufacturer is studied experimentally performing both the major and minor magnetization loops with different ramp rates of the applied magnetic field. In order to validate the test results, a numerical model is developed and presented in this work. From the numerical model we also deduced an analytical approach for the magnetization loss in the stacks of tapes with arbitrary number of tapes in the critical state model. Comparison between the measured and estimated magnetization loss of the cable prototypes is reported as well. | 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 | 4,274 |
The paper aims to analyze the electromagnetic field components in the near field of a high frequency (HF) emission antenna. The typical case of a dipole antenna emitting Near Vertical Incident Skywave (NVIS) HF signals at two emitting frequencies (3.6 MHz and 7.1 MHz) and at 100 W input power is being discussed. The measurements have highlighted the places around the antenna where the field levels are high, from the perspective of safe exposure to electromagnetic radiation. Thus, it was found that on a line situated just beneath and parallel to the emitting antenna, the electric field strength may exceed the safety limit recommended for the population by ICNIRP guidelines. The magnetic field component however was lower than the limit in all considered cases. | High frequency data transmission over short distances (few tens-few hundreds of km) is a valuable option for communication links in special/critical situations. Present experimental study of noise level and channel availability for digital multi-carrier modulated signals in the range 2.5–7.6MHz showed that reliable transmission is possible when signal to noise ratio exceeds 14dB and when receiving location is well characterized empirically prior to link deployment. | The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) is making and testing 20 insertion region dipoles for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets have the same coil design as the arc dipoles now operating in the Relativistic Heavy Ion Collider (RHIC) at BNL and will be of single and twin aperture cold mass configurations. They will produce fields up to 4.14 T for operation at 7.56 TeV. The magnets will be tested at 4.5 K using either forced flow supercritical helium or liquid helium. This paper reports the results of tests of four D1 magnets, including spontaneous quench performance, verification of quench protection heater operation, and magnetic field quality. | eng_Latn | 4,275 |
High-Speed and Schlieren Imaging of a Low Power Inductively Coupled Plasma Source for Potential Biomedical Applications | High-speed and Schlieren imaging have been used to visualize ignition transients, discharge behavior and flow fields of a plasma device integrating a low-power inductively coupled plasma torch, generating a high temperature thermal plasma, with a quenching device, able to cool the gaseous effluent down to biocompatible temperatures for effective use in biomedical applications. | In this paper, we consider the second order wave equation discretized in space by summation-by-parts-simultaneous approximation term (SBP-SAT) technique. Special emphasis is placed on the accuracy analysis of the treatment of the Dirichlet boundary condition and of the grid interface condition. The result shows that a boundary or grid interface closure with truncation error $\mathcal{O}(h^p)$ converges of order $p + 2$ if the penalty parameters are chosen carefully. We show that stability does not automatically yield a gain of two orders in convergence rate. The accuracy analysis is verified by numerical experiments. | eng_Latn | 4,276 |
On the origin of deformation microstructures in austenitic stainless steel: part I—microstructures | Abstract A comprehensive characterization of room temperature deformation microstructures was carried out by transmission electron microscopy for ion irradiated and deformed AISI 316LN austenitic stainless steel. Deformation microstructures were produced by a recently developed disk-bend test method and also by a uniaxial tensile test. Cross-slip was dramatically suppressed by the radiation-induced defects and slip occurred predominantly by planar glide of Shockley partial dislocations. Deformed microstructures consisted of piled-up dislocations, nanotwin layers, stacking faults, and defect-reduced dislocation channel bands. Analyses revealed that all these features were different manifestations of the same type of deformation band, namely a composite of overlapping faulted layers produced by Shockley partial dislocations. | This paper deals with the development of a mathematical model for very high power density actively shielded air-core superconducting (SC) machines. The interacting forces of SC coils in the actively shielded SC machine are studied using a two-dimensional analytical approach. The transfer relation methodology is employed to analyze the fully air-core SC motor that is designed to reduce the weight of the machine with actively shielded coil stator. Magnetic flux and force density distributions obtained by the proposed method are compared with those obtained from finite element analyses. The results can be considered as elements of a library of tools leading toward efficient optimization and mechanical design of actively shielded SC machines. | eng_Latn | 4,277 |
Tubular discharge in a magnetic field | Visual observations of Xe discharge glow in an axial magnetic field are described. Tubular discharge is detected in a narrow range of the parameters p, I, and H. A qualitative explanation of this effect is proposed. | Abstract An exact, three-dimensional, analytical description of the current distribution in the nozzle of an MHD channel, under imposed open conditions, is obtained. Strong vorticity of the current flow and high current concentration in the small regions toward the one side of the sidewalls and near the exit of the channel are found. | eng_Latn | 4,278 |
Dynamo bifurcations in an array of driven convectionlike rolls | The bifurcations in a three-dimensional incompressible, electrically conducting fluid with an external forcing of the Roberts type have been studied numerically. The corresponding flow can serve as a model for the convection in the outer core of the Earth and is realized in an ongoing laboratory experiment aimed at demonstrating a dynamo effect. The symmetry group of the problem has been determined and special attention has been paid to symmetry breaking by the bifurcations. The nonmagnetic, steady Roberts flow loses stability to a steady magnetic state, which in turn is subject to secondary bifurcations. The secondary solution branches have been traced until they end up in chaotic states. | Abstract A very promising spin physics programme will be soon on the way at the BNL Relativistic Heavy Ion Collider (RHIC). By studying the spin asymmetries for various processes (single photon, single jet and W ± production), we will compare the different predictions obtained using some sets of polarized parton distributions, available in the recent literature. We will put some emphasise on the analysis of the anticipated errors, given the event rates expected from this high luminosity new machine and the current acceptance for the detector systems at RHIC. | eng_Latn | 4,279 |
Electron Spin Resonance Study of the Special Features of Plasma-Induced Radicals and Their Corresponding Peroxy Radicals in Polytetrafluoroethylene. | The structure of plasma-induced PTFE radicals was studied. It was shown that the effect of plasma irradiation on radical formation of PTFE was much smaller than on hydrocarbon polymers. When the plasma-irradiated PTFE was exposed to air, peroxy radicals were rapidly formed. They were markedly stable for a long period of time at room temperature. It was difficult to isolate completely each of the component radicals formed because of the presence of durable dangling-bond sites. | Abstract Asymmetric vibration of polar orthotropic circular plates of linearly varying thickness subjected to hydrostatic in-plane force are discussed on the basis of classical plate theory. An approximate solution of the problem has been obtained by the Ritz method, which employs functions based upon the static deflection of polar orthotropic plates. This method has a faster rate of convergence as compared to the polynomial co-ordinate functions. Frequency parameters of the plate with elastically restrained edge conditions are presented for the three modes of vibrations for various values of taper parameter, rigidity ratio, flexibility parameter and buckling load parameter. The critical buckling loads for elastically restrained edge conditions have been obtained. A comparison of results with those available in the literature shows an excellent agreement. | eng_Latn | 4,280 |
The tracking force on a relativistic electron beam in an ohmic plasma channel | The linearized tracking force on an electron beam propagating slightly off axis in an Ohmic plasma channel is calculated. Electron inertial effects are included in Ohm’s law. The channel of conductivity (σ), density (ne), and radius (a) is surrounded by a region of ambient plasma with conductivity (σ0), density (ne0), and radius (b). Enclosing the system is a highly conducting metallic tank. The electromagnetic fields are calculated using the frozen‐field approximation of the Maxwell field equations. The fields are expanded into monopole and dipole moments linearized in the small parameter (d/a), where (d) is the beam displacement. The electron beam is assumed to be a rigid cylinder of charge propagating at the speed of light through the channel and is not allowed to respond dynamically to the force. | The orthogonal features of the guided wave-modes have been discussed in details for a two-layered plate with a weak interface. The elastic operator is proved to be a self-adjoint operator under the weak interface modeled by the spring model. However, it is proved to be non-self-adjoint operator, and a new orthogonal relation is derived for the weak interface modeled by the density model. The theoretical analyses are verified by numerical calculations for the spring model. | eng_Latn | 4,281 |
Influence of an electric field on self-diffraction of light waves in titanosillenite | A titanosillenite crystal is used as an example to demonstrate a strong dependence of the characteristics of energy exchange by self-diffraction of light in photorefractive crystals on the initial polarizations of the interacting waves and on the presence of an external electric field. | In support of the TCV experimental campaign aiming at studying H-mode plasmas with snowflake (SF) divertor, free boundary equilibrium and stability studies were performed with the SPIDER and KINX codes. Due to the high flexibility of plasma shaping capabilities of TCV, SF divertor conditions can be reached for various plasma geometries. However, at high plasma current some configurations require poloidal field (PF) coil currents close to the machine limit. This is particularly important when the equilibrium sensitivity to the edge pedestal profiles, which is higher than for standard X-point configurations, is taken into account. That is why the configuration optimization should also include the profile sensitivity study when planning the shot scenario. | eng_Latn | 4,282 |
Elastic, piezoelectric, and dielectric properties of multidomain 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 single crystals | The elastic, piezoelectric, and dielectric constants of 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 domain engineered single crystal were determined experimentally by using ultrasonic and resonance methods. It was confirmed that the single crystal system has large electromechanical coupling coefficient k33 (∼94%) and piezoelectric constant d33 (∼2800 pC/N) if the poling is done along the [001] of pseudocubic directions. A soft shear mode with a velocity of 880 m/s was observed in the [110] direction with displacement in [110]. Using the measured data, the orientation dependence of phase velocities and electromechanical coupling coefficients were calculated. The origin of experimental errors and their influence on measured results are also examined. | Abstract A mathematical model of the dissipative plasma layer incorporating viscous forces and field line reconnection effects is described. The behavior of plasma electric field and currents in the magnetospheric tail is analysed using exact model solutions. The electric potential associated with the reconnection magnetic fields is an outer parameter of the model that enters explicitly in all of the solutions. A method for the determination of the inner dissipative parameters (conductivity and Hartman number) is worked out and their values are found. A simple generalization of the model which includes ionospheric conductivity is proposed. The obtained solutions allow one to analyse qualitatively various processes in the nightside magnetosphere for various solar wind conditions. Conditions involving B Z southward (in enhanced reconnection) result in a simple electric field mapping. B Z northward conditions, however, allow for more complicated analytic solutions consistent with observations. | eng_Latn | 4,283 |
An Easily-Constructed Rotating Tungsten Anode | A rotating tungsten anode of diameter 97 mm has been constructed by wrapping a thin tungsten plate around a water-cooled copper body with hoops. The anode was operated continuously at 40 kV and 60 mA at a target revolution of 1800 rpm, without sustaining any damage. The focus size was about 3 mm×0.6 mm. | In this paper, we extend our previous template analysis of a self-exciting Faraday disc dynamo with a linear series motor to the case of a nonlinear series motor. This introduces two additional nonlinear symmetry-breaking terms into the governing dynamo equations. We investigate the consequences for the identification of a possible template on which the unstable periodic orbits (UPOs) lie. By computing Gauss linking numbers between pairs of UPOs, we show that their values are not incompatible with those for a template for the Lorenz attractor for its classic parameter values. | kor_Hang | 4,284 |
Interaction Between a Slow Magnetohydrodynamic Shock Wave and a Tangential Discontinuity | The self-similar problem of the oblique interaction between a slow MHD shock wave and a tangential discontinuity is solved within the framework of the ideal magnetohydrodynamic model. The constraints on the initial parameters necessary for the existence of a regular solution are found. Various feasible wave flow patterns are found in the steady-state coordinate system moving with the line of intersection of the discontinuities. As distinct from the problems of interaction between fast shock waves and other discontinuities, when the incident shock wave is slow the state ahead of it cannot be given and must to be determined in the process of solving the problem. As an example, a flow in which the slow shock wave incident on the tangential discontinuity is generated by an ideally conducting wedge located in the flow is considered. The basic features of the developing flows are determined. | Abstract An exact, three-dimensional, analytical description of the current distribution in the nozzle of an MHD channel, under imposed open conditions, is obtained. Strong vorticity of the current flow and high current concentration in the small regions toward the one side of the sidewalls and near the exit of the channel are found. | eng_Latn | 4,285 |
Electromagnetic modulations of electron whistlers in plasmas | This paper presents a formulation of the nonlinear coupling of the electron whistler mode radiation with generalized (including higher frequencies than allowed by the magnetohydrodynamic model) magnetosonic fluctuations. A coupled set of nonlinear equations describing the interaction of the whistler wave electric field with the density and the field-aligned magnetic fluctuations of the generalized magnetosonic waves is derived and the problem of modula-tional instability is discussed. Our results have relevance to the non-thermal magnetic field fluctuations which lead to supplementary plasma heating. | To attenuate the negative effects brought by heavy unsprung mass of the decentralized driving electric vehicle, a novel e-DVA module featuring of synergy between driving and vibration attenuation is proposed in this paper. It presents the advantages of compact structure and low cost. Structure design proves the feasibility of the e-DVA module. Kinematic analysis of the slider-crank mechanism is carried out to conclude the transmission ratio ripple under road excitation. After parameter matching and optimization of the e-DVA module based on the norm criterions, vertical dynamics analyses in both frequency and time domains are conducted theoretically to prove the performance improvements on the ride comfort and handling stability under the constraint of DVA deflection bound. | eng_Latn | 4,286 |
Modeling of MHD Stability Consistent to the Transport | scales (10 -6 to 10 2 m ), and these are linked with each other. Especially, the tokamak burning plasma has an autonomous property due to the large fusion power against the additional heating power and due to the large bootstrap current against the total current. To predict and control the burning plasma, the simulation code including these complex factors is necessary. At the present, it is not realistic to simulate the whole burning plasma based on the first principle such as the particle simulation. Therefore, the modeling of the various physics in tokamak plasmas and the integration of the models are necessary. In this paper, the plan of the integrated modeling of the tokamak physics is described and the progress on the modeling of Edge Localized Mode (ELM) is presented. | According to Mazhai Oil Field's hostile sandstone reservoir factors,we introduce HD surfactant.Laboratory tests indicate that the HD surfactant suit high salt and high temperature oil floor,and can improve effectually oil quality.6 well times of injection well Permeability control jobs were completed,the cumulative increased oil was 2937t.Thus HD surfactant suit Mazhai Oil Field.So HD is a good oil displacement agent. | eng_Latn | 4,287 |
TUNNEL IONIZATION AND MAGNETIC FIELD GENERATION | Abstract The possibility of the generation of a megagaus magnetic field in a plasma, creating at atom tunnel ionization in a high-power laser radiation field has been predicted. | In this paper,the soil disturbance induced by the construction process of dry-cement jet mixing columns,the change of the radial stress and the tangential stress,and the analytial solution of the radial displacement are all analysed in this paper,the analytial solution to the boundary between the plastic section and the elastic section is also included. | yue_Hant | 4,288 |
Scattering of ordinary‐mode electromagnetic waves by density fluctuations in tokamaks | Discussion and applications are presented for two approaches for estimating the effects of scattering of electromagnetic waves by turbulent density fluctuations in tokamaks. Ordinary‐mode waves propagating nearly perpendicular to the equilibrium magnetic field are considered. The multiple‐scattering approach provides analytic results for the angular and spatial spreading of a microwave beam by the turbulence. The single‐scattering approach yields numerical results and is derived by a compact technique involving Wigner functions. Both approaches are applied to idealized tokamaks to clarify relationships between the approaches and to test limits of applicability of the multiple‐scattering approach. | In the context of structural health monitoring (SHM) applications, this article first presents an example of damage detection uncertainty in a typical fiberglass woven thermoplastic plate structure with pre-embedded disbonds of various sizes and locations. A Taguchi experimental design has been implemented to statistically assess the significance of uncertainty in the performed ultrasonic NDT tests. Next, a Gaussian Process (GP)-based SHM framework has been suggested to account for such possible uncertainties in training datasets of SHM applications, and hence arriving at more robust damage systems. | eng_Latn | 4,289 |
T cell receptor beta-chain gene rearrangement without gamma-chain gene rearrangement in cutaneous T cell lymphoma: an unusual finding. | T cells from the blood and skin of a patient with cutaneous T cell lymphoma demonstrated rearrangement of the T cell receptor beta-chain gene in the absence of rearrangement of the gamma-chain gene. To our knowledge, this has not been previously reported. This finding was unexpected in light of prevailing concepts of T cell ontogeny. Potential explanations for it are discussed. | Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten-Lan-van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfvenic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the "diamond-chain" structure due to multiple shock reflections. Under a uniform resistivity, Sweet-Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection. | eng_Latn | 4,290 |
Two-dimensional calculation of tokamak stability | A numerical procedure for determining the hydromagnetic stability of axisymmetric systems is described. The growth rates and eigenfunctions are determined by means of a modified initial value method. A number of tokamak configurations have been studied and stability boundaries and growth rates are given. With a conducting wall on the plasma the fundamental toroidal mode is stable and the m = 1 mode is stable for q 1/2. | A new modeling method based on sample data is described in this paper,through physics and sample date analysis on displacement vs.voltage characteristics of x-y plane of cylindrical piezoelectric scanner used in scanning probe microscope(SPM).Through sample data statistical analysis,and considering the error factors such as scan speed,scan angle,nonlinearity and coupling,a model represented by a binomial plus some error expressions is constructed.A nonlinearity correction expression based on the model is deduced.With the software Matlab this nonlinearity correction is simulated.The result of simulation indicates that it can eliminate the errors effectively.The ascendency of the method is that there are no polarization mechanism analysis and fewer number of model parameters.The method is practical applied to engineering. | eng_Latn | 4,291 |
Stimulated scattering of electromagnetic ordinary waves from electron plasma waves at the upper hybrid frequency | Stimulated scattering of electromagnetic waves of ordinary polarization incident on a magnetized plasma from electrostatic waves propagating normal to an external magnetic field at the upper hybrid frequency is studied. The analysis is based on a multiple‐time‐scale perturbation expansion of the fluid equations, incorporating the effects of temperature, collisions, and the spatial variation of the pump wave. The threshold intensity required for the process and the growth rate above threshold are calculated. | Abstract We consider a class of staggered grid schemes for solving the 1D Euler equations in internal energy formulation. The proposed schemes are applicable to arbitrary equations of state and high-order accurate in both space and time on smooth flows. Adding a discretization of the kinetic energy equation, a high-order kinetic energy synchronization procedure is introduced, preserving globally total energy and enabling proper shock capturing. Extension to nD Cartesian grids is done via C-type staggering and high-order dimensional splitting. Numerical results are provided up to 8th-order accuracy. | eng_Latn | 4,292 |
Effect of neutral injection on impurity diffusion in a collisional tokamak | Changes in the diffusion fluxes in a plasma due to continuous neutral particle injection are calculated for the PFirsch-Schlueter case. | Application of the AVL Video System to investigate the combustion process in the cylinder of CC490ZQ turbo charged diesel engine in real working conditions of low and medium speeds with different loads is introduced, and the HC, CO, and NO_x emissions are measured and analyzed by the authors at the same time. It is found that the intake swirl is a main controlling factor of the flame distribution in initial stages in cylinder, the portion diffusive combustion has been increased and the ignition delay is shorten with the intake pressure increased, and the combustion has been improved. | eng_Latn | 4,293 |
Geometrical aspects of jet quenching in JEWEL | In this publication the performance of the Monte Carlo event generator JEWEL in non-central heavy-ion collisions is investigated. JEWEL is a consistent perturbative framework for jet evolution in the presence of a dense medium. It yields a satisfactory description of a variety of jet observables in central collisions at the LHC, although so far with a simplistic model of the medium. Here, it is demonstrated that also jet measurements in non-central collisions, and in particular the dependence of the jet suppression on the angle relative to the reaction plane, are reproduced by the same model. | Abstract Reducing the specimen-probe spacing to increase the sensitivity of measurement of weak remanence in geological samples, etc. introduces potential inaccuracies. These are analysed by comparing the field distributions derived for transversely magnetized cylinders with those for dipoles and for nulling coils. An optimum coil geometry is found. | eng_Latn | 4,294 |
Relaying of High Voltage Interconnection Transmission Lines | This paper presents an operating engineer's point of view of the practical and theoretical problems presented in applying relays for the protection of high voltage open wire interconnection transmission lines. It points out that the relaying of such lines involves problems which are not ordinarily present in the relaying of intra-system lines. These problems are enumerated and the extent to which modern relaying meets them is discussed. It is shown that the most satisfactory schemes are very expensive and the cheaper schemes are not entirely effective. The limitations of available schemes are discussed and their economics compared. A theoretical solution is proposed. | Two dimensional hybrid simulations with particle ions and fluid electrons are used to calculate the kinetic evolution of the Kelvin-Helmholtz instability at a boundary similar to the ionopause at the planet Venus. The magnetic field has been chosen to be essentially transverse to the plasma flow velocity, which is the most unstable case for the Kelvin-Helmholtz instability. Effects analogous to those found in MHD simulations are recovered, including a mode cascade to longer wavelengths. In addition, isolated structures on the order of the ion gyroradium are formed which can cross the boundary in either direction. These structures may be related to flux ropes commonly observed near the ionopause of Venus. The time evolution of these structures may represent transport across the boundary layers and the smearing of the shear layer may give rise to internal structure in the boundary. Similar processes occur in magnetized layers skin to the Earth's magnetopause. | eng_Latn | 4,295 |
On the Triggering of M-Class Solar Flare due to Loop-loop Interaction in AR NOAA 10875 | We present multiwavelength analysis of an M7.9 /1N solar flare which occurred on 27 April 2006 in AR NOAA 10875. The flare was triggered due to the interaction of two loop systems. GOES soft X-ray and TRACE 195 {\AA} image sequences show the observational evidences of 3-D X-type loop-loop interaction with converging motion at the interaction site. We found the following characteristics during the loop- loop interaction: (i) a short duration/impulsive flare obeying the Neupart effect, (ii) double peak structure in radio flux profiles (in 4.9 and 8.8 GHz), (iii) quasi-periodic oscillations in the radio flux profiles for the duration of \sim3 min, (iv) absence of CME and type III radio burst. The above characteristics observed during the flare are in agreement with the theory and simulation of current loop coalescence by Sakai et al. (1986). These are unique multiwavelength observations, which provide the evidences of loop-loop interaction and associated triggering of solar flare without CME. | We have studied the variation of the ODMR effect according to the intensity of a microwave field. We have highlighted a saturation effect of ODMR lines. This effect has been studied as part of the kinetic theory by developing the pilot equation while utilizing for the first time the formalism of a superoperator coupled with a time dependent sinusoidal perturbation. The agreement of the best fit between the experiment and the theory gives the mixing between singlet and quintuplet states, which seems to depend on the direction of the applied magnetic field. | kor_Hang | 4,296 |
Ion-acoustic wave induced convective cells | It is shown that a finite-amplitude ion-acoustic wave in a uniform magneto- plasma can enhance two-dimensional plasma vortices. The latter results from a modulational instability. The growth rates are obtained analytically. | After making some critical comments about the traditional method of extracting the gluon condensate from lattice QCD data, I present an alternative analysis. The result is more than a factor of five larger than the phenomenological value. Two closely related subjects, the effects of the infrared renormalons on the extraction and the Lepage and Mackenzie improvement on a lattice perturbation series, are also discussed. | eng_Latn | 4,297 |
Free-electron lasers driven by laser plasma accelerators | Laser-plasma accelerators (LPAs) have the potential to drive compact free-electron lasers (FELs). Even with LPA energy spreads typically at the percent level, the e-beam brightness can be excellent, due to the low normalized emittance (<0.5 µm) and high peak current (multi-kA) resulting from the ultra-short e-beam duration (few fs). It is critical, however, that in order to mitigate the effect of percent-level energy spread, one has to actively manipulate the phase-space distribution of the e-beam. We provide an overview of the methods proposed by the various LPA FEL research groups. At the BELLA Center at LBNL, we are pursuing the use of a chicane for longitudinal e-beam decompression (therefore greatly reducing the slice energy spread), in combination with short-scale-length e-beam transportation with an active plasma lens and a strong-focusing 4-m-long undulator. We present ELEGANT & GENESIS simulations on the transport and FEL gain, showing strong enhancement in output power over the incoherent backgr... | We report on the first direct numerical simulation of drift-Alfven wave turbulence in three-dimensional magnetic field geometries. It is found that the local metric has significant influence on instability and transport and that local shear contributes as the principal damping mechanism in low-global-shear field configurations. An example of such configurations are advanced stellarator fusion concepts. The transition from simple tokamak to stellarator geometry and effects on plasma edge turbulence and anomalous transport are investigated in flux-tube models of the equilibria and suitable interpolations. In the conclusion we outline a possible optimization in regard to turbulent transport reduction of steliarator configurations. | eng_Latn | 4,298 |
Plasma diffusion in a toroidal stellarator | Particle trajectories in a gently toroidal stellarator are investigated. The distribution function for the particles is determined in the absence of collisions. | Using a pump-probe Michelson experiment, we test the theory of thermo-optic (TO) effects in dielectric mirror coatings. We observe partial cancellation between coating expansion and TO effects. We also measure relevant thin film material parameters. | eng_Latn | 4,299 |
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