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on non - k \ " ahler manifolds the notion of harmonic maps is modified to that of hermitian harmonic maps in order to be compatible with the complex structure. the resulting semilinear elliptic system is { \ it not } in divergence form. the case of noncompact complete preimage and target manifolds is considered. we give conditions for existence and uniqueness of hermitian - harmonic maps and solutions of the corresponding parabolic system, which observe the non - divergence form of the underlying equations. numerous examples illustrate the theoretical results and the fundamental difference to harmonic maps.
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arxiv:math/0303137
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while the existence of a spin - liquid ground state of the spin - 1 / 2 kagome heisenberg antiferromagnet ( khaf ) is well established, the discussion of the effect of an interlayer coupling ( ilc ) by controlled theoretical approaches is still lacking. here we study this problem by using the coupled - cluster method to high orders of approximation. we consider a stacked khaf with a perpendicular ilc $ j _ \ perp $, where we study ferro - as well as antiferromagnetic $ j _ \ perp $. we find that the spin - liquid ground state ( gs ) persists until relatively large strengths of the ilc. only if the strength of the ilc exceeds about 15 \ % of the intralayer coupling the spin - liquid phase gives way for $ q = 0 $ magnetic long - range order, where the transition between both phases is continuous and the critical strength of the ilc, $ | j ^ c _ \ perp | $, is almost independent of the sign of $ j _ \ perp $. thus, by contrast to the quantum gs selection of the strictly two - dimensional khaf at large spin $ s $, the ilc leads first to a selection of the $ q = 0 $ gs. only at larger $ | j _ \ perp | $ the ilc drives a first - order transition to the $ \ sqrt { 3 } \ times \ sqrt { 3 } $ long - range ordered gs. as a result, the stacked spin - 1 / 2 khaf exhibits a rich gs phase diagram with two continuous and two discontinuous transitions driven by the ilc.
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arxiv:1510.04898
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we demonstrate that for a cosmic variance limited experiment, cmb e polarization alone places stronger constraints on cosmological parameters than cmb temperature. for example, we show that ee can constrain parameters better than tt by up to a factor 2. 8 when a multipole range of l = 30 - 2500 is considered. we expose the physical effects at play behind this remarkable result and study how it depends on the multipole range included in the analysis. in most relevant cases, te or ee surpass the tt based cosmological constraints. this result is important as the small scale astrophysical foregrounds are expected to have a much reduced impact on polarization, thus opening the possibility of building cleaner and more stringent constraints of the lcdm model. this is relevant specially for proposed future cmb satellite missions, such as core or prism, that are designed to be cosmic variance limited in polarization till very large multipoles. we perform the same analysis for a planck - like experiment, and conclude that even in this case te alone should determine the constraint on $ \ omega _ ch ^ 2 $ better than tt by 15 %, while determining $ \ omega _ bh ^ 2 $, $ n _ s $ and $ \ theta $ with comparable accuracy. finally, we explore a few classical extensions of the lcdm model and show again that cmb polarization alone provides more stringent constraints than cmb temperature in case of a cosmic variance limited experiment.
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arxiv:1403.5271
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the dimensionally regularized massless on - shell planar triple box feynman diagram with powers of propagators equal to one is analytically evaluated for general values of the mandelstam variables s and t in a laurent expansion in the parameter \ ep = ( 4 - d ) / 2 of dimensional regularization up to a finite part. an explicit result is expressed in terms of harmonic polylogarithms, with parameters 0 and 1, up to the sixth order. the evaluation is based on the method of feynman parameters and multiple mellin - barnes representation. the same technique can be quite similarly applied to planar triple boxes with any numerators and integer powers of the propagators.
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arxiv:hep-ph/0305142
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in this paper, we calculate $ ro ( c _ 2 ) $ - graded cohomology of $ c _ 2 $ - equivariant eilenberg - mac lane spaces $ k ( \ underline { z / 2 }, n + \ sigma ) $ for $ n \ geq 0 $. these can be used to give the relation between equivariant lambda algebra and equivariant adams resolution and equivariant unstable adams spectral sequence, which are defined in author ` s dissertation.
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arxiv:2301.04714
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in the context of galerkin discretizations of a partial differential equation ( pde ), the modes of the classical method of proper orthogonal decomposition ( pod ) can be interpreted as the ansatz and trial functions of a low - dimensional galerkin scheme. if one also considers a galerkin method for the time integration, one can similarly define a pod reduction of the temporal component. this has been described earlier but not expanded upon - - probably because the reduced time discretization globalizes time which is computationally inefficient. however, in finite - time optimal control systems, time \ textit { is } a global variable and there is no disadvantage from using a pod reduced galerkin scheme in time. in this paper, we provide a newly developed generalized theory for space - time galerkin pod, prove its optimality in the relevant function spaces, show its application for the optimal control of nonlinear pdes, and, by means of a numerical example with burgers ' equation, discuss the competitiveness by comparing to standard approaches.
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arxiv:1611.04050
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background. the calculation of diffusion - controlled ligand binding rates is important for understanding enzyme mechanisms as well as designing enzyme inhibitors. we demonstrate the accuracy and effectiveness of a lagrangian particle - based method, smoothed particle hydrodynamics ( sph ), to study diffusion in biomolecular systems by numerically solving the time - dependent smoluchowski equation for continuum diffusion. results. the numerical method is first verified in simple systems and then applied to the calculation of ligand binding to an acetylcholinesterase monomer. unlike previous studies, a reactive robin boundary condition ( bc ), rather than the absolute absorbing ( dirichlet ) boundary condition, is considered on the reactive boundaries. this new boundary condition treatment allows for the analysis of enzymes with " imperfect " reaction rates. rates for inhibitor binding to mache are calculated at various ionic strengths and compared with experiment and other numerical methods. we find that imposition of the robin bc improves agreement between calculated and experimental reaction rates. conclusions. although this initial application focuses on a single monomer system, our new method provides a framework to explore broader applications of sph in larger - scale biomolecular complexes by taking advantage of its lagrangian particle - based nature.
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arxiv:1501.04240
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heterogeneous graph neural networks ( hgnns ) have been widely applied in heterogeneous information network tasks, while most hgnns suffer from poor scalability or weak representation when they are applied to large - scale heterogeneous graphs. to address these problems, we propose a novel relation - aware heterogeneous graph neural network with contrastive learning ( rhco ) for large - scale heterogeneous graph representation learning. unlike traditional heterogeneous graph neural networks, we adopt the contrastive learning mechanism to deal with the complex heterogeneity of large - scale heterogeneous graphs. we first learn relation - aware node embeddings under the network schema view. then we propose a novel positive sample selection strategy to choose meaningful positive samples. after learning node embeddings under the positive sample graph view, we perform a cross - view contrastive learning to obtain the final node representations. moreover, we adopt the label smoothing technique to boost the performance of rhco. extensive experiments on three large - scale academic heterogeneous graph datasets show that rhco achieves best performance over the state - of - the - art models.
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arxiv:2211.11752
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we present the photoluminescence excitation study of the self - assembled cdte / znte quantum dots doped with manganese ions. we demonstrate the identification method of spontaneously coupled quantum dots pairs containing single mn2 + ions. as the result of the coupling, the resonant absorption of the photon in one quantum dot is followed by the exciton transfer into a neighboring dot. it is shown that the mn2 + ion might be present in the absorbing, emitting or both quantum dots. the magnetic properties of the mn2 + spin are revealed by a characteristic sixfold splitting of the excitonic line. the statistics of the value of this splitting is analyzed for the large number of the dots and gives the information on the maximum density of the neutral exciton wave function.
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arxiv:1310.3383
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we consider a partially overdetermined problem in a sector - like domain $ \ omega $ in a cone $ \ sigma $ in $ \ mathbb { r } ^ n $, $ n \ geq 2 $, and prove a rigidity result of serrin type by showing that the existence of a solution implies that $ \ omega $ is a spherical sector, under a convexity assumption on the cone. we also consider the related question of characterizing constant mean curvature compact surfaces $ \ gamma $ with boundary which satisfy a " gluing " condition with respect to the cone $ \ sigma $. we prove that if either the cone is convex or the surface is a radial graph then $ \ gamma $ must be a spherical cap. finally we show that, under the condition that the relative boundary of the domain or the surface intersects orthogonally the cone, no other assumptions are needed.
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arxiv:1802.03197
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anomaly detection aims to separate anomalies from normal samples, and the pretrained network is promising for anomaly detection. however, adapting the pretrained features would be confronted with the risk of pattern collapse when finetuning on one - class training data. in this paper, we propose an anomaly detection framework called constrained adaptive projection with pretrained features ( cap ). combined with pretrained features, a simple linear projection head applied on a specific input and its k most similar pretrained normal representations is designed for feature adaptation, and a reformed self - attention is leveraged to mine the inner - relationship among one - class semantic features. a loss function is proposed to avoid potential pattern collapse. concretely, it considers the similarity between a specific data and its corresponding adaptive normal representation, and incorporates a constraint term slightly aligning pretrained and adaptive spaces. our method achieves state - ofthe - art anomaly detection performance on semantic anomaly detection and sensory anomaly detection benchmarks including 96. 5 % auroc on cifar - 100 dataset, 97. 0 % auroc on cifar - 10 dataset and 89. 9 % auroc on mvtec dataset.
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arxiv:2112.02597
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stochastic dynamics in the energy representation is employed as a method to study non - equilibrium brownian - like systems. it is shown that the equation of motion for the energy of such systems can be taken in the form of the langevin equation with multiplicative noise. properties of the steady states are examined by solving the fokker - planck equation for the energy distribution functions. the generalized integral fluctuation theorem is deduced for the systems characterized by the shifted probability flux operator. there are a number of entropy and fluctuation relations such as the hatano - sasa identity and the jarzynski ' s equality that follow from this theorem.
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arxiv:1001.4805
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we give new examples of terminal and log canonical singularities.
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arxiv:1107.2864
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we give a general method to compute the expansion of topological tau functions for drinfeld - sokolov hierarchies associated to an arbitrary untwisted affine kac - moody algebra. our method consists of two main steps : first these tau functions are expressed as ( formal ) fredholm determinants of the type appearing in the borodin - okounkov formula, then the kernels for these determinants are found using a reduced form of the string equation. a number of explicit examples are given.
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arxiv:1505.00556
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we introduce a class of optical media based on adiabatically modulated, dielectric - only, and potentially extremely low - loss, photonic crystals. the media we describe represent a generalization of the eikonal limit of transformation optics ( to ). the foundation of the concept is the possibility to fit frequency isosurfaces in the k - space of photonic crystals with elliptic surfaces, allowing them to mimic the dispersion relation of light in anisotropic effective media. photonic crystal cloaks and other to devices operating at visible wavelengths can be constructed from optically transparent substances like glasses, whose attenuation coefficient can be as small as 10 db / km, suggesting the to design methodology can be applied to the development of optical devices not limited by the losses inherent to metal - based, passive metamaterials.
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arxiv:1007.3227
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electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. we combine structural information based on x - ray computed tomography, experimental dielectric data, and electromagnetic full - wave simulations, to study microscale electromagnetic heating of realistic three - dimensional heterogeneous explosives. we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive - binder meso - structures, and compare the heating rate for various binder systems.
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arxiv:1512.01499
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the use of artificial atoms as an active lasing medium opens a way to construct novel sources of nonclassical radiation. an example is the creation of photon - number squeezed light. here we present a design of a laser consisting of multiple cooper - pair transistors coupled to a microwave resonator. over a broad range of experimentally realizable parameters, this laser creates photon - number squeezed microwave radiation, characterized by a fano factor $ f \ ll 1 $, at a very high resonator photon number. we investigate the impact of gate - charge disorder in a cooper - pair transistor and show that the system can create squeezed strong microwave fields even in the presence of maximum disorder.
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arxiv:1611.07484
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functional data analysis has become a tool of interest in applied areas such as economics, medicine, and chemistry. among the techniques developed in recent literature, functional semiparametric regression stands out for its balance between flexible modelling and output interpretation. despite the large variety of research papers dealing with scalar - on - function ( sof ) semiparametric models, there is a notable gap in software tools for their implementation. this article introduces the r package \ texttt { fsemipar }, tailored for these models. \ texttt { fsemipar } not only estimates functional single - index models using kernel smoothing techniques but also estimates and selects relevant scalar variables in semi - functional models with multivariate linear components. a standout feature is its ability to identify impact points of a curve on the response, even in models with multiple functional covariates, and to integrate both continuous and pointwise effects of functional predictors within a single model. in addition, it allows the use of location - adaptive estimators based on the $ k $ - nearest - neighbours approach for all the semiparametric models included. its flexible interface empowers users to customise a wide range of input parameters and includes the standard s3 methods for prediction, statistical analysis, and estimate visualization ( \ texttt { predict }, \ texttt { summary }, \ texttt { print }, and \ texttt { plot } ), enhancing clear result interpretation. throughout the article, we illustrate the functionalities and the practicality of \ texttt { fsemipar } using two chemometric datasets.
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arxiv:2405.14048
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this chapter discusses how the plumed plugin for molecular dynamics can be used to analyze and bias molecular dynamics trajectories. the chapter begins by introducing the notion of a collective variable and by then explaining how the free energy can be computed as a function of one or more collective variables. a number of practical issues mostly around periodic boundary conditions that arise when these types of calculations are performed using plumed are then discussed. later parts of the chapter discuss how plumed can be used to perform enhanced sampling simulations that introduce simulation biases or multiple replicas of the system and monte carlo exchanges between these replicas. this section is then followed by a discussion on how free - energy surfaces and associated error bars can be extracted from such simulations by using weighted histogram and block averaging techniques.
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arxiv:1812.08213
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we present mid - infrared ( 2 - 12 micron ) spectra of the microquasar ss 433 obtained with the infrared space observatory ( spectroscopic mode of isophot and isocam ). we compare them to the spectra of four wolf - rayet stars : wr78, wr134, wr136, and wr147 in the same wavelength range. the mid - infrared spectrum of ss 433 mainly shows hi and hei emission lines and is very similar to the spectrum of wr147, a wn8 ( h ) + b0. 5v binary. the 2 - 12 micron continuum emission of ss 433 corresponds to optically thin and partially optically thick free - free emission, from which we calculate a mass loss rate of 2 - 3 x 10 ^ { - 4 } msun / yr if the wind is homogeneous and a third of these values if it is clumped. this is consistent with a strong stellar wind from a wn star. however, following recent studies concluding that the mass donor star of ss 433 is not a wolf - rayet star, we propose that this strong wind out flows from a geometrically thick envelope of material that surrounds the compact object like a stellar atmosphere, imitating the wolf - rayet phenomenon. this wind could also wrap the mass donor star, and at larger distances ( ~ 40 au ), it might form a dust envelope from which the thermal emission, detected with isophot at 25 micron and 60 micron, would originate. this wind also probably feeds the material that is ejected in the orbital plane of the binary system and that forms the equatorial outflow detected in radio at distances > 100 au.
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arxiv:astro-ph/0512190
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we show that final state interactions ( fsi ) within a cpt invariant two - channel framework can enhance the charge - parity ( cp ) violation difference between $ d ^ 0 \ to \ pi ^ - \ pi ^ + $ and $ d ^ 0 \ to k ^ - k ^ + $ decays up to the current experimental value. this result relies upon : ( i ) the dominant tree level diagram, ( ii ) the well - known experimental values for the $ d ^ 0 \ to \ pi ^ - \ pi ^ + $ and $ d ^ 0 \ to k ^ - k ^ + $ branching ratios, and ( iii ) the $ \ pi \ pi \ to \ pi \ pi $ and $ \ pi \ pi \ to k k $ scattering data to extract the strong phase difference and inelasticity. based on well - grounded theoretical properties, we find the sign and bulk value of the $ \ delta a _ { cp } $ and $ a _ { cp } ( d ^ 0 \ to \ pi ^ - \ pi ^ + ) $ recently observed by the lhcb collaboration.
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arxiv:2203.04056
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in this paper we propose aleph, a leaderless, fully asynchronous, byzantine fault tolerant consensus protocol for ordering messages exchanged among processes. it is based on a distributed construction of a partially ordered set and the algorithm for reaching a consensus on its extension to a total order. to achieve the consensus, the processes perform computations based only on a local copy of the data structure, however, they are bound to end with the same results. our algorithm uses a dual - threshold coin - tossing scheme as a randomization strategy and establishes the agreement in an expected constant number of rounds. in addition, we introduce a fast way of validating messages that can occur prior to determining the total ordering. this version of the protocol is deprecated. for current version see arxiv : 1908. 05156.
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arxiv:1810.05256
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we investigate the hydrostatic approximation of a hyperbolic version of navier - stokes equations, which is obtained by using cattaneo type law instead of fourier law, evolving in a thin strip $ \ r \ times ( 0, \ varepsilon ) $. the formal limit of these equations is a hyperbolic prandtl type equation. we first prove the global existence of solutions to these equations under a uniform smallness assumption on the data in gevrey $ 2 $ class. then we justify the limit globally - in - time from the anisotropic hyperbolic navier - stokes system to the hyperbolic prandtl system with such gevrey $ 2 $ class data. compared with \ cite { pzz2 } for the hydrostatic approximation of 2 - d classical navier - stokes system with analytic data, here the initial data belong to the gevrey $ 2 $ class, which is very sophisticated even for the well - posedness of the classical prandtl system ( see \ cite { dg19, wwz1 } ), furthermore, the estimate of the pressure term in the hyperbolic prandtl system arises additional difficulties.
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arxiv:2111.12836
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in this paper, we consider the zero - viscosity limit of the navier - stokes equations in a half space with the navier friction boundary condition $ $ ( \ beta u ^ { \ varepsilon } - \ varepsilon ^ { \ gamma } \ partial _ y u ^ { \ varepsilon } ) | _ { y = 0 } = 0, $ $ where $ \ beta $ is a constant and $ \ gamma \ in ( 0, 1 ] $. in the case of $ \ gamma = 1 $, the convergence to the euler equations and the prandtl equation with the robin boundary condition is justified for the analytic data. in the case of $ \ gamma \ in ( 0, 1 ) $, the convergence to the euler equations and the linearized prandtl equation is justified for the data in the gevrey class $ \ frac 1 { \ gamma } $.
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arxiv:1805.10063
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a secure key distribution ( exchange ) scheme is unconditionally secure if it is unbreakable against arbitrary technological improvements of computing power and / or any development of new algorithms. there are only two families of experimentally realized and tested unconditionally secure key distribution technologies : quantum key distribution ( qkd ), the base of quantum cryptography, which utilizes quantum physical photonic features ; and the kirchhoff - law - johnson - noise ( kljn ) system that is based on classical statistical physics ( fluctuation - dissipation theorem ). the focus topic of this paper is the thermodynamical situation of the kljn system. in all the original works, the proposed kljn schemes required thermal equilibrium between the devices of the communicating parties to achieve perfect security. however, vadai, et al, in ( nature ) science reports 5 ( 2015 ) 13653 shows a modified scheme, where there is a non - zero thermal noise energy flow between the parties, yet the system seems to resist all the known attack types. we introduce a new attack type against their system. the new attack utilizes coincidence events between the line current and voltages. we show that there is non - zero information leak toward the eavesdropper, even under idealized conditions. as soon as the thermal equilibrium is restored, the system becomes perfectly secure again. in conclusion, perfect unconditional security requires thermal equilibrium.
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arxiv:2105.12592
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generalized permutohedra are deformations of regular permutohedra, and arise in many different fields of mathematics. one important characterization of generalized permutohedra is the submodular theorem, which is related to the deformation cone of the braid fan. we lay out general techniques for determining deformation cones of a fixed polytope and apply it to the braid fan to obtain a natural combinatorial proof for the submodular theorem. we also consider a refinement of the braid fan, called the nested braid fan, and construct usual ( respectively, generalized ) nested permutohedra which have the nested braid fan as ( respectively, refining ) their normal fan. we extend many results on generalized permutohedra to this new family of polytopes, including a one - to - one correspondence between faces of nested permutohedra and chains in ordered partition posets, and a theorem analogous to the submodular theorem. finally, we show that the nested braid fan is the barycentric subdivision of the braid fan, which gives another way to construct this new combinatorial object.
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arxiv:1710.01899
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we study the bandwidth and the pathwidth of multi - dimensional grids. it can be shown for grids, that these two parameters are equal to a more basic graph parameter, the vertex boundary width. using this fact, we determine the bandwidth and the pathwidth of three - dimensional grids, which were known only for the cubic case. as a by - product, we also determine the two parameters of multi - dimensional grids with relatively large maximum factors.
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arxiv:1101.0964
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the constraints induced by prohibited zones ( pzs ) were traditionally formulated as multiple disjoint regions. it was difficult to solve the optimal power flow ( opf ) problems subject to the disjoint constraints. this paper proposes a new formulation for the opf problem with pzs. the proposed formulation significantly expedites the algorithm implementation. the effectiveness of the new approach is verified by different methods including traditional optimization methods, pso and particle swarm optimization with adaptive parameter control which is conducted on the ieee 30 - bus test system.
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arxiv:1805.03769
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to investigate the cosmic no hair conjecture, we analyze numerically 1 - dimensional plane symmetrical inhomogeneities due to gravitational waves in vacuum spacetimes with a positive cosmological constant. assuming periodic gravitational pulse waves initially, we study the time evolution of those waves and the nature of their collisions. as measures of inhomogeneity on each hypersurface, we use the 3 - dimensional riemann invariant $ { \ cal i } \ equiv { } ~ ^ { ( 3 ) \! } r _ { ijkl } ~ ^ { ( 3 ) \! } r ^ { ijkl } $ and the electric and magnetic parts of the weyl tensor. we find a temporal growth of the curvature in the waves ' collision region, but the overall expansion of the universe later overcomes this effect. no singularity appears and the result is a ` ` no hair " de sitter spacetime. the waves we study have amplitudes between $ 0. 020 \ lambda \ leq { \ cal i } ^ { 1 / 2 } \ leq 125. 0 \ lambda $ and widths between $ 0. 080l _ h \ leq l \ leq 2. 5l _ h $, where $ l _ h = ( \ lambda / 3 ) ^ { - 1 / 2 } $, the horizon scale of de sitter spacetime. this supports the cosmic no hair conjecture.
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arxiv:gr-qc/9305014
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compact obscured nuclei ( cons ) account for a significant fraction of the population of luminous and ultraluminous infrared galaxies ( lirgs and ulirgs ). these galaxy nuclei are compact, with radii of 10 - 100 ~ pc, with large optical depths at submm and far - infrared wavelengths, and characterized by vibrationally excited hcn emission. it is not known what powers the large luminosities of the con host galaxies because of the extreme optical depths towards their nuclei. cons represent an extreme phase of nuclear growth, hiding either a rapidly accreting supermassive black hole or an abnormal mode of star formation. here we apply principal component analysis ( pca ) tomography to high - resolution ( 0. 06 $ ^ { \ prime \ prime } $ ) alma observations at frequencies 245 to 265 ~ ghz of the nearby con ( 59 ~ mpc ) ic ~ 860. pca is a technique to unveil correlation in the data parameter space, and we apply it to explore the morphological and chemical properties of species in our dataset. the leading principal components reveal morphological features in molecular emission that suggest a rotating, infalling disk or envelope, and an outflow analogous to those seen in galactic protostars. one particular molecule of astrochemical interest is methanimine ( ch $ _ 2 $ nh ), a precursor to glycine, three transitions of which have been detected towards ic 860. we estimate the average ch $ _ 2 $ nh column density towards the nucleus of ic ~ 860 to be $ \ sim10 ^ { 17 } $ cm $ ^ { - 2 } $, with an abundance exceeding $ 10 ^ { - 8 } $ relative to molecular hydrogen, using the rotation diagram method and non - lte radiative transfer models. this ch $ _ 2 $ nh abundance is consistent with those found in hot cores of molecular clouds in the milky way. our analysis suggests that cons are an important stage of chemical evolution in galaxies, that are chemically and morphologically similar to milky way hot cores.
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arxiv:2210.04499
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in recent years, traffic flow prediction has played a crucial role in the management of intelligent transportation systems. however, traditional prediction methods are often limited by static spatial modeling, making it difficult to accurately capture the dynamic and complex relationships between time and space, thereby affecting prediction accuracy. this paper proposes an innovative traffic flow prediction network, sfadnet, which categorizes traffic flow into multiple traffic patterns based on temporal and spatial feature matrices. for each pattern, we construct an independent adaptive spatio - temporal fusion graph based on a cross - attention mechanism, employing residual graph convolution modules and time series modules to better capture dynamic spatio - temporal relationships under different fine - grained traffic patterns. extensive experimental results demonstrate that sfadnet outperforms current state - of - the - art baselines across four large - scale datasets.
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arxiv:2501.04060
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the classical reduced - form and filtration expansion framework in credit risk is extended to the case of multiple, non - ordered defaults, assuming that conditional densities of the default times exist. intensities and pricing formulas are derived, revealing how information driven default contagion arises in these models. we then analyze the impact of ordering the default times before expanding the filtration. while not important for pricing, the effect is significant in the context of risk management, and becomes even more pronounced for highly correlated and asymmetrically distributed defaults. finally, we provide a general scheme for constructing and simulating the default times, given that a model for the conditional densities has been chosen.
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arxiv:1104.5272
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controlling magnetic anisotropy by orbital magnetic moments related to interfacial strains has considerable potential for the development of future devices using spins and orbitals. for the fundamental physics, the relationship between strain and orbital magnetic moment is still unknown, because there are few tools to probe changes of orbital magnetic moment. in this study, we developed an electric - field - ( e ) - induced x - ray magnetic circular dichroism ( exmcd ) technique to apply e to a ferroelectric batio3 substrate. we reversibly tuned the interfacial lattice constants of ni / cu multilayers on batio3 using this technique. as the domain structures in batio3 are modulated by e, exmcd measurements reveal that the changes in the magnetic anisotropy of ni / cu films are induced through the modulation of orbital magnetic moments in ni with magneto - elastic contributions. the strained ni layer that induces the perpendicular magnetic anisotropy without e is released at e = 8 kv / cm, and in - plane magnetization also occurs. we observed that exmcd measurements clarified the origin of the reversible changes in perpendicular magnetic anisotropy and established the relationship between macroscopic inverse magnetostriction effects and microscopic orbital moment anisotropy.
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arxiv:1904.09719
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we propose the concepts of intersection distribution and non - hitting index, which can be viewed from two related perspectives. the first one concerns a point set $ s $ of size $ q + 1 $ in the classical projective plane $ pg ( 2, q ) $, where the intersection distribution of $ s $ indicates the intersection pattern between $ s $ and the lines in $ pg ( 2, q ) $. the second one relates to a polynomial $ f $ over a finite field $ \ mathbb { f } _ q $, where the intersection distribution of $ f $ records an overall distribution property of a collection of polynomials $ \ { f ( x ) + cx \ mid c \ in \ mathbb { f } _ q \ } $. these two perspectives are closely related, in the sense that each polynomial produces a $ ( q + 1 ) $ - set in a canonical way and conversely, each $ ( q + 1 ) $ - set with certain property has a polynomial representation. indeed, the intersection distribution provides a new angle to distinguish polynomials over finite fields, based on the geometric property of the corresponding $ ( q + 1 ) $ - sets. among the intersection distribution, we identify a particularly interesting quantity named non - hitting index. for a point set $ s $, its non - hitting index counts the number of lines in $ pg ( 2, q ) $ which do not hit $ s $. for a polynomial $ f $ over a finite field $ \ mathbb { f } _ q $, its non - hitting index gives the summation of the sizes of $ q $ value sets $ \ { f ( x ) + cx \ mid x \ in \ mathbb { f } _ q \ } $, where $ c \ in \ mathbb { f } _ q $. we derive bounds on the non - hitting index and show that the non - hitting index contains much information about the corresponding set and the polynomial. more precisely, using a geometric approach, we show that the non - hitting index is sufficient to characterize the corresponding point set and the polynomial when it is close to the lower and upper bounds. moreover, we employ an algebraic approach to derive the intersection distribution of several families of point sets and polynomials, and compute the sizes of related kakeya sets in affine planes.
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arxiv:2003.06678
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in this paper, we study lefschetz properties of artinian reductions of stanley - reisner rings of balanced simplicial $ 3 $ - polytopes. a $ ( d - 1 ) $ - dimensional simplicial complex is said to be balanced if its graph is $ d $ - colorable. if a simplicial complex is balanced, then its stanley - reisner ring has a special system of parameters induced by the coloring. we prove that the artinian reduction of the stanley - reisner ring of a balanced simplicial $ 3 $ - polytope with respect to this special system of parameters has the strong lefschetz property if the characteristic of the base field is not two or three. moreover, we characterize $ ( 2, 1 ) $ - balanced simplicial polytopes, i. e., polytopes with exactly one red vertex and two blue vertices in each facet, such that an analogous property holds. in fact, we show that this is the case if and only if the induced graph on the blue vertices satisfies a laman - type combinatorial condition.
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arxiv:1606.02028
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github ' s copilot for pull requests ( prs ) is a promising service aiming to automate various developer tasks related to prs, such as generating summaries of changes or providing complete walkthroughs with links to the relevant code. as this innovative technology gains traction in the open source software ( oss ) community, it is crucial to examine its early adoption and its impact on the development process. additionally, it offers a unique opportunity to observe how developers respond when they disagree with the generated content. in our study, we employ a mixed - methods approach, blending quantitative analysis with qualitative insights, to examine 18, 256 prs in which parts of the descriptions were crafted by generative ai. our findings indicate that : ( 1 ) copilot for prs, though in its infancy, is seeing a marked uptick in adoption. ( 2 ) prs enhanced by copilot for prs require less review time and have a higher likelihood of being merged. ( 3 ) developers using copilot for prs often complement the automated descriptions with their manual input. these results offer valuable insights into the growing integration of generative ai in software development.
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arxiv:2402.08967
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the majority of internet traffic is video content. this drives the demand for video compression to deliver high quality video at low target bitrates. optimising the parameters of a video codec for a specific video clip ( per - clip optimisation ) has been shown to yield significant bitrate savings. in previous work we have shown that per - clip optimisation of the lagrangian multiplier leads to up to 24 % bd - rate improvement. a key component of these algorithms is modeling the r - d characteristic across the appropriate bitrate range. this is computationally heavy as it usually involves repeated video encodes of the high resolution material at different parameter settings. this work focuses on reducing this computational load by deploying a nn operating on lower bandwidth features. our system achieves bd - rate improvement in approximately 90 % of a large corpus with comparable results to previous work in direct optimisation.
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arxiv:2204.09056
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we carried out deep mapping observations of the atomic hydrogen ( hi ) 21 cm line emission in a field centered on the famous galaxy group stephan ' s quintet ( sq ), using the five - hundred - meter aperture spherical telescope ( fast ) equipped with the 19 - beam receiver. the final data cube reaches an hi column density sensitivity of $ 5 \ sigma = 2. 1 \ times 10 ^ { 17 } $ cm $ ^ { - 2 } $ per 20 km s $ ^ { - 1 } $ channel with an angular resolution of $ 4 '. 0 $. the discovery of a large diffuse feature of the hi emission in the outskirt of the intragroup medium of sq was reported in a previous paper ( xu et al. 2022 ). here we present a new study of the total hi emission of sq and the detection of several neighboring galaxies, exploiting the high sensitivity and the large sky coverage of the fast observations. a total hi mass of $ m _ { \ rm hi } = 3. 48 \ pm 0. 35 \ times 10 ^ { 10 } \ ; m _ \ odot $ is found for sq, which is significantly higher than previous measurements in the literature. this indicates that, contrary to earlier claims, sq is not hi deficient. the excessive hi gas is mainly found in the velocity ranges of 6200 - 6400 km s $ ^ { - 1 } $ and 6800 - 7000 km s $ ^ { - 1 } $, which was undetected in previous observations that are less sensitive than ours. our results suggest that the ` ` missing hi " in compact groups may be hidden in the low - density diffuse neutral gas instead of in the ionized gas.
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arxiv:2306.11231
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minwise hashing ( minhash ) is a widely popular indexing scheme in practice. minhash is designed for estimating set resemblance and is known to be suboptimal in many applications where the desired measure is set overlap ( i. e., inner product between binary vectors ) or set containment. minhash has inherent bias towards smaller sets, which adversely affects its performance in applications where such a penalization is not desirable. in this paper, we propose asymmetric minwise hashing ( mh - alsh ), to provide a solution to this problem. the new scheme utilizes asymmetric transformations to cancel the bias of traditional minhash towards smaller sets, making the final " collision probability " monotonic in the inner product. our theoretical comparisons show that for the task of retrieving with binary inner products asymmetric minhash is provably better than traditional minhash and other recently proposed hashing algorithms for general inner products. thus, we obtain an algorithmic improvement over existing approaches in the literature. experimental evaluations on four publicly available high - dimensional datasets validate our claims and the proposed scheme outperforms, often significantly, other hashing algorithms on the task of near neighbor retrieval with set containment. our proposal is simple and easy to implement in practice.
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arxiv:1411.3787
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we investigate a possibility of odd - parity multipole orderings in a locally noncentrosymmetric tetragonal compound cecosi. by performing symmetrical and microscopic mean - field analyses on a two - orbital tight - binding model, we propose potential odd - parity multipoles hidden in staggered antiferromagnetic and antiferroquadrupole orderings in cecosi. we show that $ 3z ^ 2 - r ^ 2 $ type of the magnetic quadrupole is induced by the staggered magnetic dipole ordering for a large crystal - field splitting between two orbitals, while $ xy $ type of the electric toroidal quadrupole is emergent by the staggered electric quadrupole ordering for a small crystal - field splitting. furthermore, we discuss a magneto - electric effect and elastic - electric effect due to the odd - parity multipoles, which will be useful to identify order parameters in cecosi.
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arxiv:1912.02422
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the vertex cover problem is one of the most important and intensively studied combinatorial optimization problems. khot and regev ( 2003 ) proved that the problem is np - hard to approximate within a factor $ 2 - \ epsilon $, assuming the unique games conjecture ( ugc ). this is tight because the problem has an easy 2 - approximation algorithm. without resorting to the ugc, the best inapproximability result for the problem is due to dinur and safra ( 2002 ) : vertex cover is np - hard to approximate within a factor 1. 3606. we prove the following unconditional result about linear programming ( lp ) relaxations of the problem : every lp relaxation that approximates vertex cover within a factor $ 2 - \ epsilon $ has super - polynomially many inequalities. as a direct consequence of our methods, we also establish that lp relaxations ( as well as sdp relaxations ) that approximate the independent set problem within any constant factor have super - polynomial size.
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arxiv:1503.00753
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mean motion resonance. stability analysis indicates that this configuration is stable over million years of evolution.
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arxiv:1910.08522
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this study employs an improved volume of fluid method and adaptive mesh refinement algorithm to numerically investigate the internal jet - like mixing upon the coalescence of two initially stationary droplets of unequal sizes. the emergence of the internal jet is attributed to the formation of a main vortex ring, as the jet - like structure shows a strong correlation with the main vortex ring inside the merged droplet. by tracking the evolution of the main vortex ring together with its circulation, we identified two mechanisms that are essential to the internal - jet formation : the vortex - ring growth and the vortex - ring detachment. recognizing that the manifestation of the vortex - ring - induced jet physically relies on the competition between the convection and viscous dissipation of the vortex ring, we further developed and substantiated a vortex - ring - based reynolds number criterion to interpret the occurrence of the internal jet at various ohnesorge numbers and size ratios. for the merged droplet with apparent jet formation, the average mixing rate after jet formation increases monotonically with the vortex - ring reynolds number, which therefore serves as an approximate measure of the jet strength. in this respect, stronger internal jet is responsible for enhanced mixing of the merged droplet.
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arxiv:1706.07214
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the fourth chapter of the collection of problems in cosmology, devoted to black holes. consists of basic introduction, sections on schwarzschild and kerr black holes, a section on particles ' motion and collisions in general black hole space - times, and the astrophysical part. this version contains only formulations of 137 problems. the full collection, with solutions included, is available in the form of a wiki - based resource at www. universeinproblems. com. the cosmological community is welcome to contribute to its development.
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arxiv:1305.0259
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we propose a model of transport in thick - film resistors which naturally explains the observed nonuniversal values of the conductance exponent t extracted in the vicinity of the percolation transition. essential ingredients of the model are the segregated microstructure typical of thick - film resistors and tunneling between the conducting grains. nonuniversality sets in as consequence of wide distribution of interparticle tunneling distances.
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arxiv:cond-mat/0307141
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we study universal quadratic forms over totally real number fields using dedekind zeta functions. in particular, we prove an explicit upper bound for the rank of universal quadratic forms over a given number field $ k $, under the assumption that the codifferent of $ k $ is generated by a totally positive element. motivated by a possible path to remove that assumption, we also investigate the smallest number of generators for the positive part of ideals in totally real numbers fields.
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arxiv:2311.12911
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the exact period determination of a multi - periodic variable star based on its luminosity time series data is believed a task requiring skill and experience. thus the majority of available time series analysis techniques require human intervention to some extent. the present work is dedicated to establish an automated method of period ( or frequency ) determination from the time series database of variable stars. relying on the sigspec method ( reegen 2007 ), the technique established here employs a statistically unbiased treatment of frequency - domain noise and avoids spurious ( i. e. noise induced ) and alias peaks to the highest possible extent. several add - on ' s were incorporated to tailor sigspec to our requirements. we present tests on 386 stars taken from asas2 project database. from the output file produced by sigspec, the frequency with maximum spectral significance is chosen as the genuine frequency. out of 386 variable stars available in the asas2 database, our results contain 243 periods recovered exactly and also 88 half periods, 42 different periods etc. sigspec has the potential to be effectively used for fully automated period detection from variable stars ' time series database. the exact detection of periods helps us to identify the type of variability and classify the variable stars, which provides a crucial information on the physical processes effective in stellar atmospheres.
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arxiv:1005.3599
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wasp - 33 is a fast rotating, main sequence star which hosts a hot jupiter moving along a retrograde and almost polar orbit with semi - major axis a = 0. 02 au and eccentricity provisionally set to e = 0. the quadrupole mass moment j _ 2 and the proper angular momentum s of the star are 1900 and 400 times, respectively, larger than those of the sun. thus, huge classical and relativistic non - keplerian orbital effects should take place in such a system. in this paper we investigate the perspectives in detecting them ( abridged )
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arxiv:1006.2707
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william w. ; lyson, thomas a. ( 1988 ). high tech, low tech, no tech : recent industrial and occupational change in the south. suny press. isbn 978 - 0 - 88706 - 729 - 7. de decker, kris ( 2012 ). low - tech magazine ( tome 1 and 2 ). low - tech magazine. isbn 978 - 1 - 79471 - 152 - 5. watson, julia ( 2020 ). lo — tek. design by radical indigenism. taschen. isbn 978 - 3 - 8365 - 7818 - 9. ginn, peter ( 2019 ). slow tech : the perfect antidote to today ' s digital world. haynes uk. isbn 978 - 1 - 78521 - 616 - 9. = = references = = general merriam webster dictionary = = external links = = low - tech magazine – doubts on progress and technology low - tech lab ( english version )
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https://en.wikipedia.org/wiki/Low_technology
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we give a proof of linear inviscid damping and vorticity depletion for non - monotonic shear flows with one critical point in a bounded periodic channel. in particular, we obtain quantitative depletion rates for the vorticity function without any symmetry assumptions.
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arxiv:2301.00288
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within the framework of unified approach we study the casimir - lifshitz interaction, the van der waals friction force and the radiative heat transfer at nonequilibrium conditions, when the interacting bodies are at different temperatures, and they move relative to each other with the arbitrary velocity $ v $. the analysis is focused on the surface - surface and surface - particle configuration. our approach is based on the exact solution of electromagnetic problem about the determination of the fluctuating electromagnetic field in the vacuum gap between two flat parallel surfaces moving relative to each other with the arbitrary velocity $ v $. the velocity dependence of the considered phenomena is determined by doppler shift and can be strong for resonant photon tunneling between surface modes. we show that relativistic effects give rise to a mixing of the contributions from the electromagnetic waves with different polarization to the heat transfer and the interaction forces. we find that these effects are of the order $ ( v / c ) ^ 2 $. the limiting case when one of the bodies is sufficiently rarefied gives the heat transfer and the interaction forces between a moving small particle and a surface. we also calculate the friction force acting on a particle moving with an arbitrary velocity relative to the black body radiation.
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arxiv:0807.1004
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isomers close to the doubly magic nucleus $ ^ { 78 } $ ni ( $ z = 28 $, $ n = 50 $ ) provide essential information on the shell evolution and shape coexistence far from stability. the existence of a long - lived isomeric state in $ ^ { 76 } $ cu has been debated for a long time. we have performed high - precision mass measurements of $ ^ { 76 } $ cu with the jyfltrap double penning trap mass spectrometer at the ion guide isotope separator on - line facility and confirm the existence of such a isomeric state with an excitation energy $ e _ x = 64. 8 ( 25 ) $ kev. based on the ratio of detected ground - and isomeric - state ions as a function of time, we show that the isomer is the shorter - living state previously considered as the ground state of $ ^ { 76 } $ cu. the result can potentially change the conclusions made in previous works related to the spin - parity and charge radius of the $ ^ { 76 } $ cu ground state. additionally, the new $ ^ { 76 } $ cu $ ( n, \ gamma ) $ reaction $ q $ - value has an impact on the astrophysical rapid neutron - capture process.
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arxiv:2401.14018
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harer - kas - kirby conjectured that every handle decomposition of the elliptic surface e ( 1 ) _ { 2, 3 } requires both 1 - and 3 - handles. we prove that the elliptic surface e ( n ) _ { p, q } has a handle decomposition without 1 - handles for $ n \ geq 1 $ and ( p, q ) = ( 2, 3 ), ( 2, 5 ), ( 3, 4 ), ( 4, 5 ).
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arxiv:0802.3372
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physics simulations like computational fluid dynamics ( cfd ) are a computational bottleneck in computer - aided design ( cad ) optimization processes. to overcome this bottleneck, one requires either an optimization framework that is highly sample - efficient, or a fast data - driven proxy ( surrogate model ) for long - running simulations. both approaches have benefits and limitations. bayesian optimization is often used for sample efficiency, but it solves one specific problem and struggles with transferability ; alternatively, surrogate models can offer fast and often more generalizable solutions for cfd problems, but gathering data for and training such models can be computationally demanding. in this work, we leverage recent advances in optimization and artificial intelligence ( ai ) to explore both of these potential approaches, in the context of designing an optimal unmanned underwater vehicle ( uuv ) hull. our study finds that the bayesian optimization - lower condition bound ( bo - lcb ) algorithm is the most sample - efficient optimization framework and has the best convergence behavior of those considered. subsequently, we show that our dnn - based surrogate model predicts drag force on test data in tight agreement with cfd simulations, with a mean absolute percentage error ( mape ) of 1. 85 %. combining these results, we demonstrate a two - orders - of - magnitude speedup ( with comparable accuracy ) for the design optimization process when the surrogate model is used. to our knowledge, this is the first study applying bayesian optimization and dnn - based surrogate modeling to the problem of uuv design optimization, and we share our developments as open - source software.
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arxiv:2304.12420
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we present a sequent calculus for the modal grzegorczyk logic grz allowing non - well - founded proofs and obtain the cut - elimination theorem for it by constructing a continuous cut - elimination mapping acting on these proofs.
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arxiv:1704.03258
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we outline an approach to the inverse problem of calder \ ' on that highlights the role of microlocal normal forms and propagation of singularities and extends a number of earlier results also in the anisotropic case. the main result states that from the boundary measurements it is possible to recover integrals of the unknown coefficient over certain two - dimensional manifolds called good bicharacteristic leaves. this reduces the calder \ ' on problem into solving a linear integral geometry problem ( inversion of a bicharacteristic leaf transform ).
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arxiv:1702.02136
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by using the conserved currents in the bulk space - time, we study dynamical holographic systems and the relation between thermodynamical and dynamical stability of such systems. in particular, in the probe limit a generalized free energy is defined with the property of monotonic decreasing in dynamic processes. it is then shown that the ( absolute ) thermodynamical stability implies the dynamical stability, while the linear dynamical stability implies the thermodynamical ( meta - ) stability. the holographic superfluid is taken as an example to illustrate our general formalism, where the dynamic evolution of the system in contact with a particle source is clarified by theoretical investigation and numerical verification. the case going beyond the probe limit is also discussed.
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arxiv:1912.01159
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in recent years, recommender system has become an indispensable function in all e - commerce platforms. the review rating data for a recommender system typically comes from open platforms, which may attract a group of malicious users to deliberately insert fake feedback in an attempt to bias the recommender system to their favour. the presence of such attacks may violate modeling assumptions that high - quality data is always available and these data truly reflect users ' interests and preferences. therefore, it is of great practical significance to construct a robust recommender system that is able to generate stable recommendations even in the presence of shilling attacks. in this paper, we propose graphrfi - a gcn - based user representation learning framework to perform robust recommendation and fraudster detection in a unified way. in its end - to - end learning process, the probability of a user being identified as a fraudster in the fraudster detection component automatically determines the contribution of this user ' s rating data in the recommendation component ; while the prediction error outputted in the recommendation component acts as an important feature in the fraudster detection component. thus, these two components can mutually enhance each other. extensive experiments have been conducted and the experimental results show the superiority of our graphrfi in the two tasks - robust rating prediction and fraudster detection. furthermore, the proposed graphrfi is validated to be more robust to the various types of shilling attacks over the state - of - the - art recommender systems.
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arxiv:2005.10150
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we prove that $ i ) $ if $ \ mathcal { a } $ is $ \ lambda $ - accessible and it is axiomatizable in ( finitary ) coherent logic then $ \ lambda $ - pure maps are strict monomorphisms and $ ii ) $ if there is a proper class of strongly compact cardinals and $ \ mathcal { a } $ is $ \ lambda $ - accessible then for some $ \ mu \ vartriangleright \ lambda $ every $ \ mu $ - pure map is a strict monomorphism.
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arxiv:2407.13448
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the validity of the jarzynski equation for a very simple, exactly solvable quantum system is analyzed. the implications of two different definitions of work proposed in the literature are investigated. the first one derives from measurements of the system energy at the beginning and at the end of the process under consideration making the work a classical stochastic variable with transition probabilities derived from quantum mechanics. in the second definition an operator of work is introduced and the average in the jarzynski equation is a quantum expectation value. for the first definition a general quantum mechanical version of the jarzynski equation is known to hold. for the second one the jarzynski equation fails to yield the free energy difference at low temperature.
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arxiv:cond-mat/0612527
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we study the solvability of the second boundary value problem for a class of highly singular fourth order equations of monge - amp \ ` ere type. they arise in the approximation of convex functionals subject to a convexity constraint using abreu type equations. both the legendre transform and partial legendre transform are used in our analysis. in two dimensions, we establish global solutions to the second boundary value problem for highly singular abreu equations where the right hand sides are of $ q $ - laplacian type for all $ q > 1 $. we show that minimizers of variational problems with a convexity constraint in two dimensions that arise from the rochet - chon \ ' e model in the monopolist ' s problem in economics with $ q $ - power cost can be approximated in the uniform norm by solutions of the abreu equation for a full range of $ q $.
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arxiv:2011.05262
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we present an approach for road segmentation that only requires image - level annotations at training time. we leverage distant supervision, which allows us to train our model using images that are different from the target domain. using large publicly available image databases as distant supervisors, we develop a simple method to automatically generate weak pixel - wise road masks. these are used to iteratively train a fully convolutional neural network, which produces our final segmentation model. we evaluate our method on the cityscapes dataset, where we compare it with a fully supervised approach. further, we discuss the trade - off between annotation cost and performance. overall, our distantly supervised approach achieves 93. 8 % of the performance of the fully supervised approach, while using orders of magnitude less annotation work.
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arxiv:1708.06118
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deep neural networks for video classification, just like image classification networks, may be subjected to adversarial manipulation. the main difference between image classifiers and video classifiers is that the latter usually use temporal information contained within the video. in this work we present a manipulation scheme for fooling video classifiers by introducing a flickering temporal perturbation that in some cases may be unnoticeable by human observers and is implementable in the real world. after demonstrating the manipulation of action classification of single videos, we generalize the procedure to make universal adversarial perturbation, achieving high fooling ratio. in addition, we generalize the universal perturbation and produce a temporal - invariant perturbation, which can be applied to the video without synchronizing the perturbation to the input. the attack was implemented on several target models and the transferability of the attack was demonstrated. these properties allow us to bridge the gap between simulated environment and real - world application, as will be demonstrated in this paper for the first time for an over - the - air flickering attack.
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arxiv:2002.05123
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large - scale " foundation models " have gained traction as a way to leverage the vast amounts of unlabeled remote sensing data collected every day. however, due to the multiplicity of earth observation satellites, these models should learn " sensor agnostic " representations, that generalize across sensor characteristics with minimal fine - tuning. this is complicated by data availability, as low - resolution imagery, such as sentinel - 2 and landsat - 8 data, are available in large amounts, while very high - resolution aerial or satellite data is less common. to tackle these challenges, we introduce cross - sensor self - supervised training and alignment for remote sensing ( x - stars ). we design a self - supervised training loss, the multi - sensor alignment dense loss ( msad ), to align representations across sensors, even with vastly different resolutions. our x - stars can be applied to train models from scratch, or to adapt large models pretrained on e. g low - resolution eo data to new high - resolution sensors, in a continual pretraining framework. we collect and release msc - france, a new multi - sensor dataset, on which we train our x - stars models, then evaluated on seven downstream classification and segmentation tasks. we demonstrate that x - stars outperforms the state - of - the - art by a significant margin with less data across various conditions of data availability and resolutions.
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arxiv:2405.09922
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rise of both bachelor ' s and master ' s degree higher engineering apprenticeships. all accredited engineering courses and apprenticeships are assessed and approved by the various professional engineering institutions reflecting the subject by engineering discipline covered ; imeche, iet, bcs, ice, istructe etc. many of these institutions date back to the 19th century, and have previously administered their own engineering examination programmes. they have become globally renowned as premier learned societies. the degree then counts in part to qualifying as a chartered engineer after a period ( usually 4 – 8 years beyond the first degree ) of structured professional practice, professional practice peer review and, if required, further exams to then become a corporate member of the relevant professional body. the term ' chartered engineer ' is regulated by royal assent and its use is restricted only to those registered ; the awarding of this status is devolved to the professional institutions by the engineering council. in the uk ( except scotland ), most engineering courses take three years for an undergraduate bachelors ( beng ) and four years for an undergraduate master ' s. students who read a four - year engineering course are awarded a masters of engineering ( as opposed to masters of science in engineering ) some universities allow a student to opt out after one year before completion of the programme and receive a higher national diploma if a student has successfully completed the second year, or a higher national certificate if only successfully completed year one. many courses also include an option of a year in industry, which is usually a year before completion. students who opt for this are awarded a ' sandwich degree '. beng graduates may be registered as an " incorporated engineer " by the engineering council after a period of structured professional practice, professional practice peer review and, if required, further exams to then become a member of the relevant professional body. again, the term ' incorporated engineer ' is regulated by royal assent and its use is restricted only to those registered ; the awarding of this status is devolved to the professional institutions by the engineering council. unlike the us and canada, engineers do not require a licence to practice the profession in the uk. in the uk, the term " engineer " can be applied to non - degree vocations such as technologists, technicians, draftsmen, machinists, mechanics, plumbers, electricians, repair people, semi - skilled and even unskilled occupations. in recent developments by government and industry, to address the growing skills deficit in many fields of uk engineering, there has been a strong emphasis placed on dealing with engineering in school and providing
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https://en.wikipedia.org/wiki/Engineering_education
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zrte5 is a layered material that exhibits intricate topological effects. intensive theoretically and experimental efforts have been devoted to try to understand the physics in this materials. in this paper the temperature dependent magneto - transport properties of zrte5 thin flakes are investigated. a characteristic temperature t * is observed in the temperature dependence of three different types of magnetoresistance simultaneously, which are the saturated hall anomaly, the chiral anomaly and the longitudinal magnetoresistance. furthermore, the value of t * decreases monotonically from 200k to 160k with increasing thickness of the zrte5 thin flakes from 42nm to 89nm. temperature induced topological phase transitions are attributed to the cause of such anomaly in the three types of magnetoresistance at t *. our findings provide a multi - parameter indicator for the emergence of topological phase transition in zrte5 and could be extended to the study of other topological materials. the temperature dependence of the three types of magnetoresistance also shed light on the role of anomalous hall effect in the transport properties of zrte5.
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arxiv:2110.02759
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deep learning on the point cloud is increasingly developing. grouping the point with its neighbors and conducting convolution - like operation on them can learn the local feature of the point cloud, but this method is weak to extract the long - distance global feature. performing the attention - based transformer on the whole point cloud can effectively learn the global feature of it, but this method is hardly to extract the local detailed feature. in this paper, we propose a novel module that can simultaneously extract and fuse local and global features, which is named as ct - block. the ct - block is composed of two branches, where the letter c represents the convolution - branch and the letter t represents the transformer - branch. the convolution - branch performs convolution on the grouped neighbor points to extract the local feature. meanwhile, the transformer - branch performs offset - attention process on the whole point cloud to extract the global feature. through the bridge constructed by the feature transmission element in the ct - block, the local and global features guide each other during learning and are fused effectively. we apply the ct - block to construct point cloud classification and segmentation networks, and evaluate the performance of them by several public datasets. the experimental results show that, because the features learned by ct - block are much expressive, the performance of the networks constructed by the ct - block on the point cloud classification and segmentation tasks achieve state of the art.
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arxiv:2111.15400
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traffic congestion is rapidly increasing in urban areas, particularly in mega cities. to date, there exist a few sensor network based systems to address this problem. however, these techniques are not suitable enough in terms of monitoring an entire transportation system and delivering emergency services when needed. these techniques require real - time data and intelligent ways to quickly determine traffic activity from useful information. in addition, these existing systems and websites on city transportation and travel rely on rating scores for different factors ( e. g., safety, low crime rate, cleanliness, etc. ). these rating scores are not efficient enough to deliver precise information, whereas reviews or tweets are significant, because they help travelers and transportation administrators to know about each aspect of the city. however, it is difficult for travelers to read, and for transportation systems to process, all reviews and tweets to obtain expressive sentiments regarding the needs of the city. the optimum solution for this kind of problem is analyzing the information available on social network platforms and performing sentiment analysis. on the other hand, crisp ontology - based frameworks cannot extract blurred information from tweets and reviews ; therefore, they produce inadequate results. in this regard, this paper proposes fuzzy ontology - based sentiment analysis and swrl rule - based decision - making to monitor transportation activities and to make a city - feature polarity map for travelers. this system retrieves reviews and tweets related to city features and transportation activities. the feature opinions are extracted from these retrieved data, and then fuzzy ontology is used to determine the transportation and city - feature polarity. a fuzzy ontology and an intelligent system prototype are developed by using prot \ ' eg \ ' e owl and java, respectively.
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arxiv:1701.05334
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we characterize the irreducible representations of the general linear group gl ( v ) that have multiplicity 1 in the direct sum of all schur modules of a given exterior power of v. these have come up in connection with the relations of the lower order minors of a generic matrix. we show that the minimal relations conjectured by bruns, conca and varbaro are exactly those coming from partitions of single exterior type.
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arxiv:1308.0220
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hollow nanostructures are paid increasing attention in many nanotechnology - related communities in view of their numerous applications in chemistry and biotechnology, e. g. as smart nanoreactors or drug - delivery systems. in this paper we consider irreversible, diffusion - influenced reactions occurring within a hollow spherical cavity endowed with a circular hole on its surface. importantly, our model is not limited to small sizes of the aperture. in our scheme, reactants can freely diffuse inside and outside the cavity through the hole, and react at a spherical boundary of given size encapsulated in the chamber and endowed with a given intrinsic rate constant. we work out the solution of the above problem, enabling one to compute the reaction rate constant to any desired accuracy. remarkably, we show that, in the case of narrow holes, the rate constant is extremely well - approximated by a simple formula that can be derived on the basis of simple physical arguments and that can be readily employed to analyze experimental data.
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arxiv:1412.1969
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it is of utmost importance to have a clear understanding of the status of air pollution and to provide forecasts and insights about the air quality to the general public and researchers in environmental studies. previous studies of spatio - temporal models showed that even a short - term exposure to high concentrations of atmospheric fine particulate matters can be hazardous to the health of ordinary people. in this study, we develop a spatio - temporal model with space - time interaction for air pollution data. the proposed model uses a parametric space - time interaction component along with the spatial and temporal components in the mean structure, and introduces a random - effects component specified in the form of zero - mean spatio - temporal processes. for application, we analyze the air pollution data ( pm2. 5 ) from 66 monitoring stations across taiwan.
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arxiv:1801.00211
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this study evaluates the integration of bloom ' s taxonomy into oneclickquiz, an artificial intelligence ( ai ) driven plugin for automating multiple - choice question ( mcq ) generation in moodle. bloom ' s taxonomy provides a structured framework for categorizing educational objectives into hierarchical cognitive levels. our research investigates whether incorporating this taxonomy can improve the alignment of ai - generated questions with specific cognitive objectives. we developed a dataset of 3691 questions categorized according to bloom ' s levels and employed various classification models - multinomial logistic regression, naive bayes, linear support vector classification ( svc ), and a transformer - based model ( distilbert ) - to evaluate their effectiveness in categorizing questions. our results indicate that higher bloom ' s levels generally correlate with increased question length, flesch - kincaid grade level ( fkgl ), and lexical density ( ld ), reflecting the increased complexity of higher cognitive demands. multinomial logistic regression showed varying accuracy across bloom ' s levels, performing best for " knowledge " and less accurately for higher - order levels. merging higher - level categories improved accuracy for complex cognitive tasks. naive bayes and linear svc also demonstrated effective classification for lower levels but struggled with higher - order tasks. distilbert achieved the highest performance, significantly improving classification of both lower and higher - order cognitive levels, achieving an overall validation accuracy of 91 %. this study highlights the potential of integrating bloom ' s taxonomy into ai - driven assessment tools and underscores the advantages of advanced models like distilbert for enhancing educational content generation.
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arxiv:2504.14232
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we compute the scattering amplitude in wilson chiral perturbation theory for two flavors. the lattice spacing effects due to the explicit chiral symmetry breaking are kept through o ( a ^ 2 ), and we consider the regime where the quark mass m is of order a ^ 2 lambda _ ^ 3. analytic expressions for the scattering lengths in different isospin channels are given. as a result of the o ( a ^ 2 ) terms the scattering lengths do not vanish in the chiral limit. moreover, additional chiral logarithms proportional to a ^ 2 ln m _ pi ^ 2 are present in the one - loop results. these contributions can obscure the continuum chiral logarithms and the determination of low - energy constants from numerical lattice simulations.
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arxiv:0809.0412
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metastable states arise in a range of quantum systems and can be observed in various dynamical scenarios, including decay, bubble nucleation, and long - lived oscillations. the phenomenology of metastable states has been examined in quantum many - body systems, notably in 1d ferromagnetic ising spin systems and superfluids. in this paper, we study long - lived oscillations of metastable and ground states in 1d antiferromagnetic neutral atom chains with long - range rydberg interactions. we use a staggered local detuning field to achieve confinement. using theoretical and numerical models, we identify novel spectral signatures of quasiparticle oscillations distinct to antiferromagnetic neutral atom systems and interpret them using a classical energy model of short - range meson repulsion. finally, we evaluate the experimental accessibility of our proposed setup on current neutral - atom platforms and discuss experimental feasibility and constraints.
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arxiv:2404.12371
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computational fluid dynamics ( cfd ) is a valuable tool for personalised, non - invasive evaluation of hemodynamics in arteries, but its complexity and time - consuming nature prohibit large - scale use in practice. recently, the use of deep learning for rapid estimation of cfd parameters like wall shear stress ( wss ) on surface meshes has been investigated. however, existing approaches typically depend on a hand - crafted re - parametrisation of the surface mesh to match convolutional neural network architectures. in this work, we propose to instead use mesh convolutional neural networks that directly operate on the same finite - element surface mesh as used in cfd. we train and evaluate our method on two datasets of synthetic coronary artery models with and without bifurcation, using a ground truth obtained from cfd simulation. we show that our flexible deep learning model can accurately predict 3d wss vectors on this surface mesh. our method processes new meshes in less than 5 [ s ], consistently achieves a normalised mean absolute error of $ \ leq $ 1. 6 [ % ], and peaks at 90. 5 [ % ] median approximation accuracy over the held - out test set, comparing favourably to previously published work. this demonstrates the feasibility of cfd surrogate modelling using mesh convolutional neural networks for hemodynamic parameter estimation in artery models.
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arxiv:2109.04797
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the ability to anticipate the future is essential when making real time critical decisions, provides valuable information to understand dynamic natural scenes, and can help unsupervised video representation learning. state - of - art video prediction is based on lstm recursive networks and / or generative adversarial network learning. these are complex architectures that need to learn large numbers of parameters, are potentially hard to train, slow to run, and may produce blurry predictions. in this paper, we introduce dyan, a novel network with very few parameters and easy to train, which produces accurate, high quality frame predictions, significantly faster than previous approaches. dyan owes its good qualities to its encoder and decoder, which are designed following concepts from systems identification theory and exploit the dynamics - based invariants of the data. extensive experiments using several standard video datasets show that dyan is superior generating frames and that it generalizes well across domains.
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arxiv:1803.07201
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the backpropagation algorithm has experienced remarkable success in training large - scale artificial neural networks ; however, its biological plausibility has been strongly criticized, and it remains an open question whether the brain employs supervised learning mechanisms akin to it. here, we propose correlative information maximization between layer activations as an alternative normative approach to describe the signal propagation in biological neural networks in both forward and backward directions. this new framework addresses many concerns about the biological - plausibility of conventional artificial neural networks and the backpropagation algorithm. the coordinate descent - based optimization of the corresponding objective, combined with the mean square error loss function for fitting labeled supervision data, gives rise to a neural network structure that emulates a more biologically realistic network of multi - compartment pyramidal neurons with dendritic processing and lateral inhibitory neurons. furthermore, our approach provides a natural resolution to the weight symmetry problem between forward and backward signal propagation paths, a significant critique against the plausibility of the conventional backpropagation algorithm. this is achieved by leveraging two alternative, yet equivalent forms of the correlative mutual information objective. these alternatives intrinsically lead to forward and backward prediction networks without weight symmetry issues, providing a compelling solution to this long - standing challenge.
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arxiv:2306.04810
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tumor segmentation in pet - ct images is challenging due to the dual nature of the acquired information : low metabolic information in ct and low spatial resolution in pet. u - net architecture is the most common and widely recognized approach when developing a fully automatic image segmentation method in the medical field. we proposed a two - step approach, aiming to refine and improve the segmentation performances of tumoral lesions in pet - ct. the first step generates a prior tumor appearance map from the pet - ct volumes, regarded as prior tumor information. the second step, consisting of a standard u - net, receives the prior tumor appearance map and pet - ct images to generate the lesion mask. we evaluated the method on the 1014 cases available for the autopet 2022 challenge, and the results showed an average dice score of 0. 701 on the positive cases.
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arxiv:2210.02203
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the problem of finding weight matrices $ w ( x ) $ of size $ n \ times n $ such that the associated sequence of matrix - valued orthogonal polynomials are eigenfunctions of a second - order matrix differential operator is known as the matrix bochner problem, and it is closely related to darboux transformations of some differential operators. this paper aims to study darboux transformations between weight matrices and to establish a direct connection with the structure of the algebra $ \ mathcal d ( w ) $ of all differential operators that have a sequence of matrix - valued orthogonal polynomials with respect to $ w $ as eigenfunctions.
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arxiv:2311.16325
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expanding media are typical in many different fields, e. g. in biology and cosmology. in general, a medium expansion ( contraction ) brings about dramatic changes in the behavior of diffusive transport properties. here, we focus on such effects when the diffusion process is described by the continuous time random walk ( ctrw ) model. for the case where the jump length and the waiting time probability density functions ( pdfs ) are long - tailed, we derive a general bifractional diffusion equation which reduces to a normal diffusion equation in the appropriate limit. we then study some particular cases of interest, including l \ ' evy flights and subdiffusive ctrws. in the former case, we find an analytical exact solution for the green ' s function ( propagator ). when the expansion is sufficiently fast, the contribution of the diffusive transport becomes irrelevant at long times and the propagator tends to a stationary profile in the comoving reference frame. in contrast, for a contracting medium a competition between the spreading effect of diffusion and the concentrating effect of contraction arises. for a subdiffusive ctrw in an exponentially contracting medium, the latter effect prevails for sufficiently long times, and all the particles are eventually localized at a single point in physical space. this " big crunch " effect stems from inefficient particle spreading due to subdiffusion. we also derive a hierarchy of differential equations for the moments of the transport process described by the subdiffusive ctrw model. in the case of an exponential expansion, exact recurrence relations for the laplace - transformed moments are obtained. our results confirm the intuitive expectation that the medium expansion hinders the mixing of diffusive particles occupying separate regions. in the case of l \ ' evy flights, we quantify this effect by means of the so - called " l \ ' evy horizon ".
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arxiv:1706.06793
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of traditional continuous mathematics. = = = combinatorics = = = combinatorics studies the ways in which discrete structures can be combined or arranged. enumerative combinatorics concentrates on counting the number of certain combinatorial objects - e. g. the twelvefold way provides a unified framework for counting permutations, combinations and partitions. analytic combinatorics concerns the enumeration ( i. e., determining the number ) of combinatorial structures using tools from complex analysis and probability theory. in contrast with enumerative combinatorics which uses explicit combinatorial formulae and generating functions to describe the results, analytic combinatorics aims at obtaining asymptotic formulae. topological combinatorics concerns the use of techniques from topology and algebraic topology / combinatorial topology in combinatorics. design theory is a study of combinatorial designs, which are collections of subsets with certain intersection properties. partition theory studies various enumeration and asymptotic problems related to integer partitions, and is closely related to q - series, special functions and orthogonal polynomials. originally a part of number theory and analysis, partition theory is now considered a part of combinatorics or an independent field. order theory is the study of partially ordered sets, both finite and infinite. = = = graph theory = = = graph theory, the study of graphs and networks, is often considered part of combinatorics, but has grown large enough and distinct enough, with its own kind of problems, to be regarded as a subject in its own right. graphs are one of the prime objects of study in discrete mathematics. they are among the most ubiquitous models of both natural and human - made structures. they can model many types of relations and process dynamics in physical, biological and social systems. in computer science, they can represent networks of communication, data organization, computational devices, the flow of computation, etc. in mathematics, they are useful in geometry and certain parts of topology, e. g. knot theory. algebraic graph theory has close links with group theory and topological graph theory has close links to topology. there are also continuous graphs ; however, for the most part, research in graph theory falls within the domain of discrete mathematics. = = = number theory = = = number theory is concerned with the properties of numbers in general, particularly integers. it has applications to cryptography and cryptanalysis, particularly with regard to modular arithmetic, diophantine equations, linear and quadratic congruences, prime numbers and
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https://en.wikipedia.org/wiki/Discrete_mathematics
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we theoretically predict and experimentally verify the illusion of transforming the magnetic signature of a 3d object into that of another arbitrary object. this is done by employing negative - permeability materials, which we demonstrate that can be emulated by tailored sets of currents. the experimental transformation of the magnetic response of a ferromagnet into that of its antagonistic material, a superconductor, is presented to confirm the theory. the emulation of negative - permeability materials by currents provides a new pathway for designing devices for controlling magnetic fields in unprecedented ways.
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arxiv:1803.08009
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we study the quantum mechanical model obtained as a dimensional reduction of n = 1 super yang - mills theory to a periodic light - cone " time ". after mapping the theory to a cohomological field theory, the partition function ( with periodic boundary conditions ) regularized by a massive term appears to be equal to the partition function of the twisted matrix oscillator. we show that this partition function perturbed by the operator of the holonomy around the time circle is a tau function of toda hierarchy. we solve the model in the large n limit and study the universal properties of the solution in the scaling limit of vanishing perturbation. we find in this limit a phase transition of gross - witten type.
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arxiv:hep-th/9907058
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one of the most powerful theorems in metric geometry is the arzela - ascoli theorem which provides a continuous limit for sequences of equicontinuous functions between two compact spaces. this theorem has been extended by gromov and grove - petersen to sequences of functions with varying domains and ranges where the domains and the ranges respectively converge in the gromov - hausdorff sense to compact limit spaces. however such a powerful theorem does not hold when the domains and ranges only converge in the intrinsic flat sense due to the possible disappearance of points in the limit. in this paper two arzela - ascoli theorems are proven for intrinsic flat converging sequences of manifolds : one for uniformly lipschitz functions with fixed range whose domains are converging in the intrinsic flat sense, and one for sequences of uniformly local isometries between spaces which are converging in the intrinsic flat sense. a basic bolzano - weierstrass theorem is proven for sequences of points in such sequences of spaces. in addition it is proven that when a sequence of manifolds has a precompact intrinsic flat limit then the metric completion of the limit is the gromov - hausdorff limit of regions within those manifolds. applications and suggested applications of these results are described in the final section of this paper.
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arxiv:1402.6066
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the main purpose of this book is to propose an introduction to the modern tools of algebraic complexity. to remain as simple as possible while providing meaningful examples, we chose to focus on effective linear algebra ; this is certainly one of the best possible choices to give an idea of the main problems in algebraic complexity. the contents of the book are the following : classical results of linear algebra and basic algorithms in linear algebra, straight - line programs as a model of computation, with an emphasis on strassen ' s method known as " elimination of divisions ", a discussion on various notions of complexity, a presentation of the general algorithmic strategy " divide and conquer ", a first important example : the fast multiplication of polynomials, the very heart of the book : the fast multiplication of matrices, with a discussion of derived fast algorithms for various problems of linear algebra. the particular case of the computation of the determinant is then discussed, and the last chapter deals with the difficult computation of the permanent ( valiant ' s conjecture ). this book gives an introduction to a fascinating subject at a reasonable level... for french - speaking people.
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arxiv:1604.00795
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following feynman and as elaborated on by lloyd, a universal quantum simulator ( qs ) is a controlled quantum device which reproduces the dynamics of any other many particle quantum system with short range interactions. this dynamics can refer to both coherent hamiltonian and dissipative open system evolution. we investigate how laser excited rydberg atoms in large spacing optical or magnetic lattices can provide an efficient implementation of a universal qs for spin models involving ( high order ) n - body interactions. this includes the simulation of hamiltonians of exotic spin models involving n - particle constraints such as the kitaev toric code, color code, and lattice gauge theories with spin liquid phases. in addition, it provides the ingredients for dissipative preparation of entangled states based on engineering n - particle reservoir couplings. the key basic building blocks of our architecture are efficient and high - fidelity n - qubit entangling gates via auxiliary rydberg atoms, including a possible dissipative time step via optical pumping. this allows to mimic the time evolution of the system by a sequence of fast, parallel and high - fidelity n - particle coherent and dissipative rydberg gates.
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arxiv:0907.1657
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we present the next - to - leading - order calculation of the partial decay widths of light cp - even higgs bosons decaying into four fermions in the two - higgs - doublet model and a singlet extension of the standard model. different renormalization schemes are applied in the calculation, which is implemented into the analysis tool prophecy4f. some sample results on the higgs - > 4fermions decay widths illustrate how the corrections reduce the dependence on the renormalization scale and the choice of the scheme.
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arxiv:1807.05876
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random teleportation is a necessary evil for ranking and clustering directed networks based on random walks. teleportation enables ergodic solutions, but the solutions must necessarily depend on the exact implementation and parametrization of the teleportation. for example, in the commonly used pagerank algorithm, the teleportation rate must trade off a heavily biased solution with a uniform solution. here we show that teleportation to links rather than nodes enables a much smoother trade - off and effectively more robust results. we also show that, by not recording the teleportation steps of the random walker, we can further reduce the effect of teleportation with dramatic effects on clustering.
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arxiv:1112.5252
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we have realized a compact system to efficiently couple the fluorescent light emitted by a single trapped ion to two opposing optical fibers. the fibers are tightly integrated in the center electrodes of a miniature endcap trap. they capture light from the ion with a numerical aperture of 0. 34 each, corresponding to 6 % of the solid angle in total. the high collection efficiency and high signal - to - background ratio make the setup an ideal quantum light source. we have observed strong antibunching of the photons emitted from the two fibers. the system has a range of applications from single - ion state detection in quantum information processing to strong coupling cavity - qed with ions.
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arxiv:1101.5877
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the generation structure in the quark and lepton spectrum is explained as originating from the excitation spectrum s _ n of su ( 2 ) _ w doublet scalar fields, whose ground state s _ 1 is the standard model higgs field. there is only one basic family of su ( 2 ) _ w doublet left - handed fermions, nu _ l, e _ l, u _ l, d _ l, whose bound states with s _ n manifest themselves as the generations of left - handed quarks and leptons. likewise, there is only one basic family of the right - handed fermions, nu _ r, e _ r, u _ r, d _ r, which combine with the gauge invariant scalar fields g _ n to produce the right - handed quarks and leptons of the second and higher generations. there are only four yukawa coupling constants, g _ nu, g _ e, g _ u, and g _ d, and all quark and lepton masses are proportional to them. suppression of flavor changing neutral currents ( gim mechanism ) is automatic. nu _ mu and nu _ tau are expected to be massive.
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arxiv:hep-ph/0002067
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consider n points on the unit 2 - sphere. the potential of the interaction of two points is a function f ( r ) of the distance r between the points. the total energy e of n points is the sum of the pairwise energies. the question is how to place the points on the sphere to minimize the energy e. for the coulomb potential f ( r ) = 1 / r, the problem goes back to thomson ( 1904 ). the results for n < 5 are well known. we focus on the case n = 5, which turns out to be difficult. in this case, the following results have been obtained. for n = 5, dragnev, legg, and townsend ( 2002 ) give a solution of the problem for f ( r ) = - log r known as whyte ' s problem. hou and shao ( 2009 ) give a rigorous computer - aided solution for f ( r ) = - r. schwartz ( 2010 ) gives a rigorous computer - aided solution of thompson ' s problem. we give a solution for biquadratic potentials.
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arxiv:1208.5044
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classical hamming graphs are cartesian products of complete graphs, and two vertices are adjacent if they differ in exactly one coordinate. motivated by connections to unitary cayley graphs, we consider a generalization where two vertices are adjacent if they have no coordinate in common. metric dimension of classical hamming graphs is known asymptotically, but, even in the case of hypercubes, few exact values have been found. in contrast, we determine the metric dimension for the entire diagonal family of $ 3 $ - dimensional generalized hamming graphs. our approach is constructive and made possible by first characterizing resolving sets in terms of forbidden subgraphs of an auxiliary edge - colored hypergraph.
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arxiv:2208.01519
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the observation of higgs pair production at high - energy colliders can give evidence for the presence of a triple higgs coupling. however, the actual determination of the value of this coupling is more difficult. in the context of general models for new physics, double higgs production processes can receive contributions from many possible beyond - standard - model effects. this dependence must be understood if one is to make a definite statement about the deviation of the higgs field potential from the standard model. in this paper, we study the extraction of the triple higgs coupling from the process $ e ^ + e ^ - \ to zhh $. we show that, by combining the measurement of this process with other measurements available at a 500 gev $ e ^ + e ^ - $ collider, it is possible to quote model - independent limits on the effective field theory parameter c6 that parametrizes modifications of the higgs potential. we present precise error estimates based on the anticipated ilc physics program, studied with full simulation. our analysis also gives new insight into the model - independent extraction of the higgs boson coupling constants and total width from $ e ^ + e ^ - $ data.
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arxiv:1708.09079
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new data on the membership of the local group, in conjunction with new and improved radial velocity data, are used to refine the derivation of the motion of the sun relative to the local group ( hereafter lg ). the sun is found to be moving with a velocity of vbulk = 306 \ pm 18 km / s, towards an apex at l = 99 \ pm 5 and b = - 4 \ pm 4 degrees. this agrees very well with previous analyses, but we discuss the possibility of a bias if the phase - space distribution of lg galaxies is bimodal. the lg radial velocity dispersion is 61 \ pm 8 km / s. we use various mass estimators to compute the mass of the local group and the andromeda subgroup. we find m _ lg = ( 2. 3 \ pm 0. 6 ) * 10 ^ 12 \ msol, from which m / l _ v = 44 \ pm 12 ( in solar units ). for an assumed lg age of 14 \ pm 2 gyr, the radius of an idealized lg zero - velocity surface is r _ 0 = 1. 18 \ pm 0. 15 mpc. the local group is found to have 35 likely members. only three of those have ( uncertain ) distances \ grtapr 1. 0 mpc from the lg barycenter. barring new discoveries of low surface brightness dwarfs, this suggests that the local group is more compact, and isolated from its surroundings, than previously believed.
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arxiv:astro-ph/9903298
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with the growing scale and complexity of video data, efficiently processing long video sequences poses significant challenges due to the quadratic increase in memory and computational demands associated with existing transformer - based large multi - modal models ( lmms ). to address these issues, we introduce video - ma $ ^ 2 $ mba, a novel architecture that incorporates state space models ( ssms ) within the mamba - 2 framework, replacing the attention mechanisms. this allows the lmms to scale linearly in terms of time and memory requirements, making it feasible to handle long - duration video content. furthermore, we enhance the memory efficiency introducing the multi - axis gradient checkpointing ( ma - gc ) method, which strategically manages memory by retaining only essential activations across multiple computational axes. our approach significantly reduces the memory footprint compared to standard gradient checkpointing. empirical analyses show that video - ma $ ^ 2 $ mba can process extensive video sequences - equivalent to millions of tokens or over two hours of continuous sequences at 1 fps - on a single gpu. by maintaining a detailed capture of temporal dynamics, our model improves the accuracy and relevance of responses in long video understanding tasks, demonstrating substantial advantages over existing frameworks.
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arxiv:2411.19460
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the bilateral asymmetry of flanks of animals with visual body marks that uniquely identify an individual, complicates tasks like population estimations. automatically generated additional information on the visible side of the animal would improve the accuracy for individual identification. in this study we used transfer learning on popular cnn image classification architectures to train a flank predictor that predicts the visible flank of quadruped mammalian species in images. we automatically derived the data labels from existing datasets originally labeled for animal pose estimation. we trained the models in two phases with different degrees of retraining. the developed models were evaluated in different scenarios of different unknown quadruped species in known and unknown environments. as a real - world scenario, we used a dataset of manually labeled eurasian lynx ( lynx lynx ) from camera traps in the bavarian forest national park to evaluate the model. the best model, trained on an efficientnetv2 backbone, achieved an accuracy of 88. 70 % for the unknown species lynx in a complex habitat.
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arxiv:2406.13588
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artificial intelligence necessitates adaptable hardware accelerators for efficient high - throughput million operations. we present pipelined architecture with cordic block for linear mac computations and nonlinear iterative activation functions ( af ) such as $ tanh $, $ sigmoid $, and $ softmax $. this approach focuses on a reconfigurable processing engine ( rpe ) based systolic array, with 40 \ % pruning rate, enhanced throughput up to 4. 64 $ \ times $, and reduction in power and area by 5. 02 $ \ times $ and 4. 06 $ \ times $ at cmos 28 nm, with minor accuracy loss. fpga implementation achieves a reduction of up to 2. 5 $ \ times $ resource savings and 3 $ \ times $ power compared to prior works. the systolic cordic engine for reconfigurability and enhanced throughput ( sycore ) deploys an output stationary dataflow with the caesar control engine for diverse ai workloads such as transformers, rnns / lstms, and dnns for applications like image detection, llms, and speech recognition. the energy - efficient and flexible approach extends the enhanced approach for edge ai accelerators supporting emerging workloads.
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arxiv:2503.11685
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we analyse dynamics of the closed type iia and iib string on various tri - vector deformed background searching for signatures of integrability. using numerical methods we construct poincar \ ' e sections for particular embeddings of the string and show that these are not destroyed under tri - vector deformation. we find that the corresponding lyapunov exponents decay showing that trajectories do not diverge.
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arxiv:2504.16773
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we elaborate a full superfield description of the interacting system of dynamical d = 4, n = 1 supergravity and dynamical superstring. as far as minimal formulation of the simple supergravity is used, such a system should contain as well the tensor ( real linear ) multiplet which describes the dilaton and the two - superform gauge field whose pull - back provides the wess - zumino term for the superstring. the superfield action is given by the sum of the wess - zumino action for d = 4, n = 1 superfield supergravity, the superfield action for the tensor multiplet in curved superspace and the green - schwarz superstring action. the latter includes the coupling to the tensor multiplet both in the nambu - goto and in the wess - zumino terms. we derive superfield equations of motion including, besides the superfield supergravity equations with the source, the source - full superfield equations for the linear multiplet. the superstring equations keep the same form as for the superstring in supergravity and 2 - superform background. the analysis of gauge symmetries shows that the superfield description of the interacting system is gauge equivalent to the dynamical system described by the sum of the spacetime, component action for supergravity interacting with tensor multiplet and of the purely bosonic string action.
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arxiv:hep-th/0308102
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in this paper, the perpendicular magnetic anisotropy ( pma ) is tailored by changing the thickness of the free layer with the objective of producing mtj nano - pillars with smooth linear resistance dependence with both in - plane magnetic field and dc bias. we furthermore demonstrate how this linear bias dependence can be used to create a zero - threshold broadband voltage rectifier, a feature which is important for rectification in wireless charging and energy harvesting applications. by carefully balancing the amount of pma acting in the free layer the measured rf to dc voltage conversion efficiency can be made as large as 11 %.
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arxiv:1804.04104
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