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2014-11-05
Kalman Filtering over Gilbert-Elliott Channels: Stability Conditions and the Critical Curve
This paper investigates the stability of Kalman filtering over Gilbert-Elliott channels where random packet drop follows a time-homogeneous two-state Markov chain whose state transition is determined by a pair of failure and recovery rates. First of all, we establish a relaxed condition guaranteeing peak-covariance sta...
1411.1217v1
2015-01-21
Lévy walks on lattices as multi-state processes
Continuous-time random walks combining diffusive scattering and ballistic propagation on lattices model a class of L\'evy walks. The assumption that transitions in the scattering phase occur with exponentially-distributed waiting times leads to a description of the process in terms of multiple states, whose distributio...
1501.05216v1
2015-01-31
Bases and Structure Constants of Generalized Splines with Integer Coefficients on Cycles
An integer generalized spline is a set of vertex labels on an edge-labeled graph that satisfy the condition that if two vertices are joined by an edge, the vertex labels are congruent modulo the edge label. Foundational work on these objects comes from Gilbert, Polster, and Tymoczko, who generalize ideas from geometry/...
1502.00176v1
2015-03-02
An Anisotropic Landau-Lifschitz-Gilbert model of dissipation in qubits
We derive a microscopic model for dissipative dynamics in a system of mutually interacting qubits coupled to a thermal bath that generalises the dissipative model of Landau-Lifschitz-Gilbert to the case of anisotropic bath couplings. We show that the dissipation acts to bias the quantum trajectories towards a reduced p...
1503.00651v2
2015-03-25
Optimising the neutron environment of Radiation Portal Monitors: a computational optimisation study
Efficient and reliable detection of radiological or nuclear threats is a crucial part of national and international efforts to prevent terrorist activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are intended to interdict smuggled fissile material by detecting emissions of neutrons and gamma ra...
1503.07346v1
2015-06-29
Energy spectra of primary knock-on atoms under neutron irradiation
Materials subjected to neutron irradiation will suffer from a build-up of damage caused by the displacement cascades initiated by nuclear reactions. Previously, the main "measure" of this damage accumulation has been through the displacements per atom (dpa) index. There are known limitations associated with the dpa qua...
1506.08554v1
2015-08-25
Direct Visualization of Memory Effects in Artificial Spin Ice
We experimentally demonstrate that arrays of interacting nanoscale ferromagnetic islands, known as artificial spin ice, develop reproducible microstates upon cycling an applied magnetic field. The onset of this memory effect is determined by the strength of the applied field relative to the array coercivity. Specifical...
1508.06330v1
2015-10-21
On the limiting Markov process of energy exchanges in a rarely interacting ball-piston gas
We analyse the process of energy exchanges generated by the elastic collisions between a point-particle, confined to a two-dimensional cell with convex boundaries, and a `piston', i.e. a line-segment, which moves back and forth along a one-dimensional interval partially intersecting the cell. This model can be consider...
1510.06408v2
2015-10-29
Deligne--Langlands gamma factors in families
Let F be a p-adic field, W_F its absolute Weil group, and let k be an algebraically closed field of prime characteristic l different from p. Attached to any l-adic representation of W_F are local epsilon- and L-factors. There are natural notions of families of l-adic representations of W_F, such as the theory of Galois...
1510.08743v3
2015-11-01
Verification of commercial motor performance for WEAVE at the William Herschel Telescope
WEAVE is a 1000-fiber multi-object spectroscopic facility for the 4.2~m William Herschel Telescope. It will feature a double-headed pick-and-place fiber positioning robot comprising commercially available robotic axes. This paper presents results on the performance of these axes, obtained by testing a prototype system ...
1511.00202v1
2015-11-02
Learning from history: Adaptive calibration of 'tilting spine' fiber positioners
This paper discusses a new approach for determining the calibration parameters of independently-actuated optical fibers in multi-object astronomical fiber positioning systems. This work comes from the development of a new type of piezoelectric motor intended to enhance the 'tilting spine' fiber positioning technology o...
1511.00737v1
2016-06-23
Echidna Mark II: one giant leap for 'tilting spine' fibre positioning technology
The Australian Astronomical Observatory's 'tilting spine' fibre positioning technology has been redeveloped to provide superior performance in a smaller package. The new design offers demonstrated closed-loop positioning errors of 2.8 {\mu}m RMS in only five moves (~10 s excluding metrology overheads) and an improved c...
1606.07305v1
2016-08-15
Inverse subsemigroups of finite index in finitely generated inverse semigroups
The index of a subgroup of a group counts the number of cosets of that subgroup. A subgroup of finite index often shares structural properties with the group, and the existence of a subgroup of finite index with some particular property can therefore imply useful structural information for the overgroup. A developed th...
1608.04254v1
2016-10-03
Magnetic microscopy and simulation of strain-mediated control of magnetization in Ni/PMN-PT nanostructures
Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated from these materials is limited. Here we characterize ferromagnetic...
1610.00746v1
2016-10-17
Formalising Real Numbers in Homotopy Type Theory
Cauchy reals can be defined as a quotient of Cauchy sequences of rationals. The limit of a Cauchy sequence of Cauchy reals is defined through lifting it to a sequence of Cauchy sequences of rationals. This lifting requires the axiom of countable choice or excluded middle, neither of which is available in homotopy type ...
1610.05072v2
2016-11-04
The flow and evolution of ice-sucrose crystal mushes
We study the rheology of suspensions of ice crystals at moderate to high volume fractions in a sucrose solution in which they are partially soluble; a model system for a wide class of crystal mushes or slurries. Under step changes in shear rate, the viscosity changes to a new `relaxed' value over several minutes, in a ...
1611.01365v1
2016-11-08
Convergence of an implicit-explicit midpoint scheme for computational micromagnetics
Based on lowest-order finite elements in space, we consider the numerical integration of the Landau-Lifschitz-Gilbert equation (LLG). The dynamics of LLG is driven by the so-called effective field which usually consists of the exchange field, the external field, and lower-order contributions such as the stray field. Th...
1611.02465v2
2016-11-17
Dynamical contribution to the heat conductivity in stochastic energy exchanges of locally confined gases
We present a systematic computation of the heat conductivity of the Markov jump process modeling the energy exchanges in an array of locally confined hard spheres at the conduction threshold. Based on a variational formula [Sasada M. 2016, {\it Thermal conductivity for stochastic energy exchange models}, arXiv:1611.088...
1611.05809v3
2016-11-27
Thermal conductivity for stochastic energy exchange models
We consider a class of stochastic models for energy transport and study relations between the thermal conductivity and some static observables, such as the static conductivity, which is defined as the contribution of static correlations in Green-Kubo formula. The class of models is a generalization of two specific mode...
1611.08866v1
2016-12-07
Spatial heterogeneity of W transmutation in a fusion device
Accurately quantifying the transmutation rate of tungsten (W) under neutron irradiation is a necessary requirement in the assessment of its performance as an armour material in a fusion power plant. The usual approach of calculating average responses, assuming large, homogenised material volumes, is insufficient to cap...
1612.03892v1
2017-01-20
Structure of optimal strategies for remote estimation over Gilbert-Elliott channel with feedback
We investigate remote estimation over a Gilbert-Elliot channel with feedback. We assume that the channel state is observed by the receiver and fed back to the transmitter with one unit delay. In addition, the transmitter gets ACK/NACK feedback for successful/unsuccessful transmission. Using ideas from team theory, we e...
1701.05943v1
2017-02-04
Fabrication of Atomically Precise Nanopores in Hexagonal Boron Nitride
We demonstrate the fabrication of individual nanopores in hexagonal boron nitride (hBN) with atomically precise control of the pore size. Previous methods of pore production in other 2D materials create pores of irregular geometry with imprecise diameters. By taking advantage of the preferential growth of boron vacanci...
1702.01220v1
2017-02-10
A finite element approximation for the stochastic Maxwell--Landau--Lifshitz--Gilbert system
The stochastic Landau--Lifshitz--Gilbert (LLG) equation coupled with the Maxwell equations (the so called stochastic MLLG system) describes the creation of domain walls and vortices (fundamental objects for the novel nanostructured magnetic memories). We first reformulate the stochastic LLG equation into an equation wi...
1702.03027v1
2017-03-07
The extrapolated explicit midpoint scheme for variable order and step size controlled integration of the Landau-Lifschitz-Gilbert equation
A practical and efficient scheme for the higher order integration of the Landau-Lifschitz-Gilbert (LLG) equation is presented. The method is based on extrapolation of the two-step explicit midpoint rule and incorporates adaptive time step and order selection. We make use of a piecewise time-linear stray field approxima...
1703.02479v1
2017-09-06
Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: implementation and validation in MuMax3
Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a time stepping algorithm with a fixed time step in order to perform micromagnetic simulations at nonzero temperatures. Howev...
1709.01682v1
2017-09-18
Growth-Induced In-Plane Uniaxial Anisotropy in V$_{2}$O$_{3}$/Ni Films
We report on a strain-induced and temperature dependent uniaxial anisotropy in V$_{2}$O$_{3}$/Ni hybrid thin films, manifested through the interfacial strain and sample microstructure, and its consequences on the angular dependent magnetization reversal. X-ray diffraction and reciprocal space maps identify the in-plane...
1709.06100v1
2018-05-07
Generalized Random Gilbert-Varshamov Codes
We introduce a random coding technique for transmission over discrete memoryless channels, reminiscent of the basic construction attaining the Gilbert-Varshamov bound for codes in Hamming spaces. The code construction is based on drawing codewords recursively from a fixed type class, in such a way that a newly generate...
1805.02515v2
2018-07-04
Deep Autoencoder for Combined Human Pose Estimation and body Model Upscaling
We present a method for simultaneously estimating 3D human pose and body shape from a sparse set of wide-baseline camera views. We train a symmetric convolutional autoencoder with a dual loss that enforces learning of a latent representation that encodes skeletal joint positions, and at the same time learns a deep repr...
1807.01511v1
2018-10-08
Hiding the weights -- CBC black box algorithms with a guaranteed error bound
The component-by-component (CBC) algorithm is a method for constructing good generating vectors for lattice rules for the efficient computation of high-dimensional integrals in the "weighted" function space setting introduced by Sloan and Wo\'zniakowski. The "weights" that define such spaces are needed as inputs into t...
1810.03394v1
2018-10-11
Alternative Stacking Sequences in Hexagonal Boron Nitride
The relative orientation of successive sheets, i.e. the stacking sequence, in layered two-dimensional materials is central to the electronic, thermal, and mechanical properties of the material. Often different stacking sequences have comparable cohesive energy, leading to alternative stable crystal structures. Here we ...
1810.04814v1
2018-10-17
Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques
Spin torques play a crucial role in operative properties of modern spintronic devices. To study current-driven magnetization dynamics, spin-torque terms providing the action of spin-polarized currents have previously often been added in a phenomenological way to the Landau-Lifshitz-Gilbert equation describing the local...
1810.07438v1
2018-10-23
Resource-Constrained Simultaneous Detection and Labeling of Objects in High-Resolution Satellite Images
We describe a strategy for detection and classification of man-made objects in large high-resolution satellite photos under computational resource constraints. We detect and classify candidate objects by using five pipelines of convolutional neural network processing (CNN), run in parallel. Each pipeline has its own un...
1810.10110v1
2018-11-01
Ludometrics: Luck, and How to Measure It
Game theory is the study of tractable games which may be used to model more complex systems. Board games, video games and sports, however, are intractable by design, so "ludological" theories about these games as complex phenomena should be grounded in empiricism. A first "ludometric" concern is the empirical measureme...
1811.00673v1
2019-01-28
Topology and Observables of the Non-Hermitian Chern Insulator
Topology plays a central role in nearly all disciplines of physics, yet its applications have so far been restricted to closed, lossless systems in thermodynamic equilibrium. Given that many physical systems are open and may include gain and loss mechanisms, there is an eminent need to reexamine topology within the con...
1901.09961v2
2019-03-25
Deep Shape from Polarization
This paper makes a first attempt to bring the Shape from Polarization (SfP) problem to the realm of deep learning. The previous state-of-the-art methods for SfP have been purely physics-based. We see value in these principled models, and blend these physical models as priors into a neural network architecture. This pro...
1903.10210v2
2019-04-30
The algebra of rewriting for presentations of inverse monoids
We describe a formalism, using groupoids, for the study of rewriting for presentations of inverse monoids, that is based on the Squier complex construction for monoid presentations. We introduce the class of pseudoregular groupoids, an example of which now arises as the fundamental groupoid of our version of the Squier...
1904.13135v1
2019-05-31
Characterizing the mod-$\ell$ local Langlands correspondence by nilpotent gamma factors
Let $F$ be a $p$-adic field and choose $k$ an algebraic closure of $\mathbb{F}_{\ell}$, with $\ell$ different from $p$. We define ``nilpotent lifts'' of irreducible generic $k$-representations of $GL_n(F)$, which take coefficients in Artin local $k$-algebras. We show that an irreducible generic $\ell$-modular represent...
1905.13487v2
2019-07-18
The homology of groups, profinite completions, and echoes of Gilbert Baumslag
We present novel constructions concerning the homology of finitely generated groups. Each construction draws on ideas of Gilbert Baumslag. There is a finitely presented acyclic group $U$ such that $U$ has no proper subgroups of finite index and every finitely presented group can be embedded in $U$. There is no algorith...
1907.08072v2
2019-08-08
Semantic Estimation of 3D Body Shape and Pose using Minimal Cameras
We aim to simultaneously estimate the 3D articulated pose and high fidelity volumetric occupancy of human performance, from multiple viewpoint video (MVV) with as few as two views. We use a multi-channel symmetric 3D convolutional encoder-decoder with a dual loss to enforce the learning of a latent embedding that enabl...
1908.03030v2
2019-09-06
The universal unramified module for GL(n) and the Ihara conjecture
Let $F$ be a finite extension of $\mathbb{Q}_p$. Let $W(k)$ denote the Witt vectors of an algebraically closed field $k$ of characteristic $\ell$ different from $p$ and $2$, and let $\mathcal{Z}$ be the spherical Hecke algebra for $GL_n(F)$ over $W(k)$. Given a Hecke character $\lambda:\mathcal{Z}\to R$, where $R$ is a...
1909.02709v3
2019-10-10
Weak-strong uniqueness for the Landau-Lifshitz-Gilbert equation in micromagnetics
We consider the time-dependent Landau-Lifshitz-Gilbert equation. We prove that each weak solution coincides with the (unique) strong solution, as long as the latter exists in time. Unlike available results in the literature, our analysis also includes the physically relevant lower-order terms like Zeeman contribution, ...
1910.04630v2
2019-11-20
Hard Choices in Artificial Intelligence: Addressing Normative Uncertainty through Sociotechnical Commitments
As AI systems become prevalent in high stakes domains such as surveillance and healthcare, researchers now examine how to design and implement them in a safe manner. However, the potential harms caused by systems to stakeholders in complex social contexts and how to address these remains unclear. In this paper, we expl...
1911.09005v1
2019-11-22
Asymmetric entanglement-assisted quantum error-correcting codes and BCH codes
The concept of asymmetric entanglement-assisted quantum error-correcting code (asymmetric EAQECC) is introduced in this article. Codes of this type take advantage of the asymmetry in quantum errors since phase-shift errors are more probable than qudit-flip errors. Moreover, they use pre-shared entanglement between enco...
1911.10031v2
2019-12-16
Nanosecond-timescale development of Faraday rotation in an ultracold gas
When a gas of ultracold atoms is suddenly illuminated by light that is nearly resonant with an atomic transition, the atoms cannot respond instantaneously. This non-instantaneous response means the gas is initially more transparent to the applied light than in steady-state. The timescale associated with the development...
1912.07553v1
2020-01-31
An efficient automated data analytics approach to large scale computational comparative linguistics
This research project aimed to overcome the challenge of analysing human language relationships, facilitate the grouping of languages and formation of genealogical relationship between them by developing automated comparison techniques. Techniques were based on the phonetic representation of certain key words and conce...
2001.11899v1
2020-03-24
An information theoretic framework for classifying exoplanetary system architectures
We propose several descriptive measures to characterize the arrangements of planetary masses, periods, and mutual inclinations within exoplanetary systems. These measures are based in complexity theory and capture the global, system-level trends of each architecture. Our approach considers all planets in a system simul...
2003.11098v1
2020-05-14
On the Performance Analysis of Streaming Codes over the Gilbert-Elliott Channel
The Gilbert-Elliot (GE) channel is a commonly-accepted model for packet erasures in networks. Streaming codes are a class of packet-level erasure codes designed to provide reliable communication over the GE channel. The design of a streaming code may be viewed as a two-step process. In the first, a more tractable, dela...
2005.06921v2
2020-08-25
Differentiating a Tensor Language
How does one compile derivatives of tensor programs, such that the resulting code is purely functional (hence easier to optimize and parallelize) and provably efficient relative to the original program? We show that naively differentiating tensor code---as done in popular systems like Tensorflow and PyTorch---can cause...
2008.11256v1
2020-09-14
Moduli of Langlands Parameters
Let $F$ be a nonarchimedean local field of residue characteristic $p$, let $\hat{G}$ be a split reductive group over $\mathbb{Z}[1/p]$ with an action of $W_F$, and let $^LG$ denote the semidirect product $\hat{G}\rtimes W_F$. We construct a moduli space of Langlands parameters $W_F \to {^LG}$, and show that it is local...
2009.06708v3
2020-09-30
Spin-diffusion model for micromagnetics in the limit of long times
In this paper, we consider spin-diffusion Landau-Lifshitz-Gilbert equations (SDLLG), which consist of the time-dependent Landau-Lifshitz-Gilbert (LLG) equation coupled with a time-dependent diffusion equation for the electron spin accumulation. The model takes into account the diffusion process of the spin accumulation...
2009.14534v1
2020-12-20
Reconstructing phase-resolved hysteresis loops from first-order reversal curves
The first order reversal curve (FORC) method is a magnetometry based technique used to capture nanoscale magnetic phase separation and interactions with macroscopic measurements using minor hysteresis loop analysis. This makes the FORC technique a powerful tool in the analysis of complex systems which cannot be effecti...
2012.11041v1
2021-01-13
Self-organization in the one-dimensional Landau-Lifshitz-Gilbert-Slonczewski equation with non-uniform anisotropy fields
In magnetic films driven by spin-polarized currents, the perpendicular-to-plane anisotropy is equivalent to breaking the time translation symmetry, i.e., to a parametric pumping. In this work, we numerically study those current-driven magnets via the Landau-Lifshitz-Gilbert-Slonczewski equation in one spatial dimension...
2101.05263v1
2021-01-20
Global Optimization of the Mean First Passage Time for Narrow Capture Problems in Elliptic Domains
Narrow escape and narrow capture problems which describe the average times required to stop the motion of a randomly travelling particle within a domain have applications in various areas of science. While for general domains, it is known how the escape time decreases with the increase of the trap sizes, for some speci...
2101.08368v2
2021-02-03
Bounds and Genericity of Sum-Rank-Metric Codes
We derive simplified sphere-packing and Gilbert--Varshamov bounds for codes in the sum-rank metric, which can be computed more efficiently than previous ones. They give rise to asymptotic bounds that cover the asymptotic setting that has not yet been considered in the literature: families of sum-rank-metric codes whose...
2102.02244v3
2021-03-01
A pathwise stochastic Landau-Lifshitz-Gilbert equation with application to large deviations
Using a rough path formulation, we investigate existence, uniqueness and regularity for the stochastic Landau-Lifshitz-Gilbert equation with Stratonovich noise on the one dimensional torus. As a main result we show the continuity of the so-called It\^o-Lyons map in the energy spaces $L^\infty(0,T;H^k)\cap L^2(0,T;H^{k+...
2103.00926v1
2021-03-17
Numerical analysis of the Landau-Lifshitz-Gilbert equation with inertial effects
We consider the numerical approximation of the inertial Landau-Lifshitz-Gilbert equation (iLLG), which describes the dynamics of the magnetization in ferromagnetic materials at subpicosecond time scales. We propose and analyze two fully discrete numerical schemes: The first method is based on a reformulation of the pro...
2103.09888v2
2021-07-12
Human-like Relational Models for Activity Recognition in Video
Video activity recognition by deep neural networks is impressive for many classes. However, it falls short of human performance, especially for challenging to discriminate activities. Humans differentiate these complex activities by recognising critical spatio-temporal relations among explicitly recognised objects and ...
2107.05319v2
2021-08-17
Small-misorientation toughness in biominerals evolved convergently
The hardest materials in living organisms are biologically grown crystalline minerals, or biominerals, which are also incredibly fracture-tough. Biomineral mesostructure includes size, shape, spatial arrangement, and crystal orientation of crystallites, observable at the mesoscale (10 nanometer - 10 micron). Here we sh...
2108.07877v1
2021-08-19
Evidence for a liquid precursor to biomineral formation
The crystals in animal biominerals such as sea urchin spines, mollusk shells, and coral skeletons, form by attachment of amorphous particles that subsequently crystallize. Do these solid amorphous precursor particles have liquid precursors? Polymer-induced liquid precursors (PILP), or prenucleation clusters coalescing ...
2108.08429v1
2021-08-22
Factors Enhancing E-Government Service Gaps in a Developing Country Context
Globally, the discourse of e-government has gathered momentum in public service delivery. No country has been left untouched in the implementation of e-government. Several government departments and agencies are now using information and communication technology (ICTs) to deliver government services and information to ...
2108.09803v1
2021-09-23
Cyclically presented groups as Labelled Oriented Graph groups
We use results concerning the Smith forms of circulant matrices to identify when cyclically presented groups have free abelianisation and so can be Labelled Oriented Graph (LOG) groups. We generalize a theorem of Odoni and Cremona to show that for a fixed defining word, whose corresponding representer polynomial has an...
2109.11463v1
2021-12-03
Spectral reconstruction in NRQCD via the Backus-Gilbert method
We present progress results from the FASTSUM collaboration's programme to determine the spectrum of the bottomonium system as a function of temperature using a variety of approaches. In this contribution, the Backus Gilbert method is used to reconstruct spectral functions from NRQCD meson correlator data from FASTSUM's...
2112.02075v2
2021-12-23
Energy minimizing maps with prescribed singularities and Gilbert-Steiner optimal networks
We investigate the relation between energy minimizing maps valued into spheres having topological singularities at given points and optimal networks connecting them (e.g. Steiner trees, Gilbert-Steiner irrigation networks). We show the equivalence of the corresponding variational problems, interpreting in particular th...
2112.12511v4
2022-02-02
Asymptotic stability of precessing domain walls for the Landau-Lifshitz-Gilbert equation in a nanowire with Dzyaloshinskii-Moriya interaction
We consider a ferromagnetic nanowire and we focus on an asymptotic regime where the Dzyaloshinskii-Moriya interaction is taken into account. First we prove a dimension reduction result via $\Gamma$-convergence that determines a limit functional $E$ defined for maps $m:\mathbb{R}\to \mathbb{S}^2$ in the direction $e_1$ ...
2202.01005v1
2022-02-14
The Higgs Boson Mass as Fundamental Parameter of the Minimal Supersymmetric Standard Model
In the Minimal Supersymmetric Standard Model (MSSM) the mass of the lightest neutral Higgs boson is determined by the supersymmetric parameters. In the $m_h$MSSM the precisely measured Higgs boson replaces the trilinear coupling $A_t$ as input parameter. Expressions are derived to extract $A_t$ in a semi-analytical for...
2202.06919v2
2022-02-15
Coding and Bounds for Partially Defective Memory Cells
This paper considers coding for so-called partially stuck (defect) memory cells. Such memory cells can only store partial information as some of their levels cannot be used fully due to, e.g., wearout. First, we present new constructions that are able to mask $u$ partially stuck cells while correcting at the same time ...
2202.07541v1
2022-03-24
Multi-platform Process Flow Models and Algorithms for Extraction and Documentation of Digital Forensic Evidence from Mobile Devices
The increasing need for the examination of evidence from mobile and portable gadgets increases the essential need to establish dependable measures for the investigation of these gadgets. Many differences exist while detailing the requirement for the examination of each gadget, to help detectives and examiners in guaran...
2203.13258v1
2022-06-07
Implicit biases in transit models using stellar pseudo-density
The transit technique is responsible for the majority of exoplanet discoveries to date. Characterizing these planets involves careful modeling of their transit profiles. A common technique involves expressing the transit duration using a density-like parameter, $\tilde{\rho}$, often called the "circular density." Most ...
2206.03432v1
2022-06-22
Homogenization of the Landau-Lifshitz-Gilbert equation with natural boundary condition
The full Landau-Lifshitz-Gilbert equation with periodic material coefficients and natural boundary condition is employed to model the magnetization dynamics in composite ferromagnets. In this work, we establish the convergence between the homogenized solution and the original solution via a Lax equivalence theorem kind...
2206.10948v1
2022-09-12
GenLoco: Generalized Locomotion Controllers for Quadrupedal Robots
Recent years have seen a surge in commercially-available and affordable quadrupedal robots, with many of these platforms being actively used in research and industry. As the availability of legged robots grows, so does the need for controllers that enable these robots to perform useful skills. However, most learning-ba...
2209.05309v1
2022-10-11
Element-Specific First Order Reversal Curves Measured by Magnetic Transmission X-ray Microscopy
The first order reversal curve (FORC) method is a macroscopic measurement technique which can be used to extract quantitative, microscopic properties of hysteretic systems. Using magnetic transmission X-ray microscopy (MTXM), local element-specific FORC measurements are performed on a 20 nm thick film of CoTb. The FORC...
2210.05739v1
2022-11-08
Landau-Lifshitz-Gilbert equations: Controllability by Low Modes Forcing for deterministic version and Support Theorems for Stochastic version
In this article, we study the controllability issues of the Landau-Lifshitz-Gilbert Equations (LLGEs), accompanied with non-zero exchange energy only, in an interval in one spatial dimension with Neumann boundary conditions. The paper is of twofold. In the first part of the paper, we study the controllability issues of...
2211.04204v1
2022-11-18
Knowledge Graph Refinement based on Triplet BERT-Networks
Knowledge graph embedding techniques are widely used for knowledge graph refinement tasks such as graph completion and triple classification. These techniques aim at embedding the entities and relations of a Knowledge Graph (KG) in a low dimensional continuous feature space. This paper adopts a transformer-based triple...
2211.10460v1
2022-11-22
Generalized Random Gilbert-Varshamov Codes: Typical Error Exponent and Concentration Properties
We find the exact typical error exponent of constant composition generalized random Gilbert-Varshamov (RGV) codes over DMCs channels with generalized likelihood decoding. We show that the typical error exponent of the RGV ensemble is equal to the expurgated error exponent, provided that the RGV codebook parameters are ...
2211.12238v1
2023-01-05
Improved Gilbert-Varshamov bounds for hopping cyclic codes and optical orthogonal codes
Hopping cyclic codes (HCCs) are (non-linear) cyclic codes with the additional property that the $n$ cyclic shifts of every given codeword are all distinct, where $n$ is the code length. Constant weight binary hopping cyclic codes are also known as optical orthogonal codes (OOCs). HCCs and OOCs have various practical ap...
2301.02042v1
2023-01-11
Thou Shalt not Pick all Items if Thou are First: of Strategyproof and Fair Picking Sequences
When allocating indivisible items to agents, it is known that the only strategyproof mechanisms that satisfy a set of rather mild conditions are constrained serial dictatorships: given a fixed order over agents, at each step the designated agent chooses a given number of items (depending on her position in the sequence...
2301.06086v1
2023-01-17
Comparison of Optical and Electrical Links for Highly-Interconnected Systems
As data rates for multi-gigabit serial interfaces within multi-node compute systems approach and exceed 10 Gigabits per second (Gbps), board-to-board and chip-to-chip optical signaling solutions become more attractive, particularly for longer (e.g. 50-100 cm) links. The transition to optical signaling will potentially ...
2301.10169v1
2023-01-17
PWB Manufacturing Variability Effects on High Speed SerDes Links: Statistical Insights from Thousands of 4-Port SParameter Measurements
Variability analysis is important in successfully deploying multi-gigabit backplane printed wiring boards (PWBs) with growing numbers of high-speed SerDes links. We discuss the need for large sample sizes to obtain accurate variability estimates of SI metrics (eye height, phase skew, etc). Using a dataset of 11,961 S...
2301.10176v1
2023-01-17
A Zero Sum Signaling Method for High Speed, Dense Parallel Bus Communications
Complex digital systems such as high performance computers (HPCs) make extensive use of high-speed electrical interconnects, in routing signals among processing elements, or between processing elements and memory. Despite increases in serializer/deserializer (SerDes) and memory interface speeds, there is demand for hig...
2302.05427v1
2023-03-20
Dynamic Documentation for AI Systems
AI documentation is a rapidly-growing channel for coordinating the design of AI technologies with policies for transparency and accessibility. Calls to standardize and enact documentation of algorithmic harms and impacts are now commonplace. However, documentation standards for AI remain inchoate, and fail to match the...
2303.10854v1
2023-01-17
56 Gbps PCB Design Strategies for Clean, Low-Skew Channels
Although next generation (>28 Gbps) SerDes standards have been contemplated for several years, it has not been clear whether PCB structures supporting 56 Gbps NRZ will be feasible and practical. In this paper, we assess a number of specific PCB design strategies (related to pin-field breakouts, via stubs, and fiber wea...
2304.01909v1
2023-01-17
Inverting the SerDes Link Design Flow Process
The traditional SerDes link simulation process begins with the extraction of printed circuit board (PCB) physical stripline and via models, followed by channel modeling and link simulation. We invert this simulation flow by first creating link performance curves across an array of hypothetical channels defined with spe...
2304.01911v1
2023-01-17
Plated-Through-Hole Via Design Specifications for 112G Serial Links
An earlier study of a high layer-count test board using plated-through-hole (PTH) vias and a limited quantity of laser vias was shown to be capable of supporting 112 Gb/s PAM-4 links (or equivalent signaling having 28 GHz (Nyquist) bandwidth). This original board design was then rebuilt using a different fabricator, an...
2304.01913v1
2023-04-18
Sample-and-Hold Safety with Control Barrier Functions
A common assumption on the deployment of safeguarding controllers on the digital platform is that high sampling frequency translates to a small violation of safety. This paper investigates and formalizes this assumption through the lens of Input-to-State Safety. From this perspective, and leveraging control barrier fun...
2304.08685v2
2023-01-17
Efficient Circuit-Level Implementation of Knuth-Based Balanced and Nearly-Balanced Codes
Coding schemes are often used in high-speed processor-processor or processor-memory busses in digital systems. In particular, we have introduced (in a 2012 DesignCon paper) a zero sum (ZS) signaling method which uses balanced or nearly-balanced coding to reduce simultaneous switching noise (SSN) in a single-ended bus t...
2304.13497v1
2023-01-17
Capacitor Optimization in Power Distribution Networks Using Numerical Computation Techniques
This paper presents a power distribution network (PDN) decoupling capacitor optimization application with three primary goals: reduction of solution times for large networks, development of flexible network scoring routines, and a concentration strictly on achieving the best network performance. Example optimizations a...
2305.01540v1
2023-05-26
Sphaleron rate from a modified Backus-Gilbert inversion method
We compute the sphaleron rate in quenched QCD for a temperature $T \simeq 1.24~T_c$ from the inversion of the Euclidean lattice time correlator of the topological charge density. We explore and compare two different strategies: one follows a new approach proposed in this study and consists in extracting the rate from f...
2305.17120v2
2023-07-21
Visibility graph-based covariance functions for scalable spatial analysis in nonconvex domains
We present a new method for constructing valid covariance functions of Gaussian processes over irregular nonconvex spatial domains such as water bodies, where the geodesic distance agrees with the Euclidean distance only for some pairs of points. Standard covariance functions based on geodesic distances are not positiv...
2307.11941v2
2023-08-23
Consistency of common spatial estimators under spatial confounding
This paper addresses the asymptotic performance of popular spatial regression estimators on the task of estimating the effect of an exposure on an outcome in the presence of an unmeasured spatially-structured confounder. This setting is often referred to as "spatial confounding." We consider spline models, Gaussian pro...
2308.12181v1
2023-09-19
Stochastic control of the Landau-Lifshitz-Gilbert equation
We consider the stochastic Landau-Lifshitz-Gilbert equation in dimension 1. A control process is added to the effective field. We show the existence of a weak martingale solution for the resulting controlled equation. The proof uses the classical Faedo-Galerkin approximation, along with the Jakubowski version of the Sk...
2309.10260v1
2023-10-13
Unified framework of the microscopic Landau-Lifshitz-Gilbert equation and its application to Skyrmion dynamics
The Landau-Lifshitz-Gilbert (LLG) equation is widely used to describe magnetization dynamics. We develop a unified framework of the microscopic LLG equation based on the nonequilibrium Green's function formalism. We present a unified treatment for expressing the microscopic LLG equation in several limiting cases, inclu...
2310.08807v1
2023-10-18
Parallel-in-Time Integration of the Landau-Lifshitz-Gilbert Equation with the Parallel Full Approximation Scheme in Space and Time
Speeding up computationally expensive problems, such as numerical simulations of large micromagnetic systems, requires efficient use of parallel computing infrastructures. While parallelism across space is commonly exploited in micromagnetics, this strategy performs poorly once a minimum number of degrees of freedom pe...
2310.11819v1
2023-12-29
Chebyshev and Backus-Gilbert reconstruction for inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD
We present a study on the nonperturbative calculation of observables for inclusive semileptonic decays of $B_{(s)}$ mesons using lattice QCD. We focus on the comparison of two different methods to analyse the lattice data of Euclidean correlation functions, specifically Chebyshev and Backus-Gilbert approaches. This typ...
2312.17401v1
2024-02-22
Gilbert-Varshamov Bound for Codes in $L_1$ Metric using Multivariate Analytic Combinatorics
Analytic combinatorics in several variables refers to a suite of tools that provide sharp asymptotic estimates for certain combinatorial quantities. In this paper, we apply these tools to determine the Gilbert--Varshamov lower bound on the rate of optimal codes in $L_1$ metric. Several different code spaces are analyze...
2402.14712v1
2024-02-28
Embodied Supervision: Haptic Display of Automation Command to Improve Supervisory Performance
A human operator using a manual control interface has ready access to their own command signal, both by efference copy and proprioception. In contrast, a human supervisor typically relies on visual information alone. We propose supplying a supervisor with a copy of the operators command signal, hypothesizing improved p...
2402.18707v1
2024-03-14
Quantum analog of Landau-Lifshitz-Gilbert dynamics
The Landau-Lifshitz-Gilbert (LLG) and Landau-Lifshitz (LL) equations play an essential role for describing the dynamics of magnetization in solids. While a quantum analog of the LL dynamics has been proposed in [Phys. Rev. Lett. 110, 147201 (2013)], the corresponding quantum version of LLG remains unknown. Here, we pro...
2403.09255v1
2024-03-15
Identification and estimation of mediational effects of longitudinal modified treatment policies
We demonstrate a comprehensive semiparametric approach to causal mediation analysis, addressing the complexities inherent in settings with longitudinal and continuous treatments, confounders, and mediators. Our methodology utilizes a nonparametric structural equation model and a cross-fitted sequential regression techn...
2403.09928v1
2024-03-22
Two-scale Analysis for Multiscale Landau-Lifshitz-Gilbert Equation: Theory and Numerical Methods
This paper discusses the theory and numerical method of two-scale analysis for the multiscale Landau-Lifshitz-Gilbert equation in composite ferromagnetic materials. The novelty of this work can be summarized in three aspects: Firstly, the more realistic and complex model is considered, including the effects of the exch...
2403.14957v1
2020-11-30
Role of Compressive Viscosity and Thermal Conductivity on the Damping of Slow Waves in the Coronal Loops With and Without Heating-Cooling Imbalance
In the present paper, we derive a new dispersion relation for slow magnetoacoustic waves invoking the effect of thermal conductivity, compressive viscosity, radiation and unknown heating term along with the consideration of heating cooling imbalance from linearized MHD equations. We solve the general dispersion relatio...
2011.14519v2
1993-06-22
Weakly Damped Modes in Star Clusters and Galaxies
A perturber may excite a coherent mode in a star cluster or galaxy. If the stellar system is stable, it is commonly assumed that such a mode will be strongly damped and therefore of little practical consequence other than redistributing momentum and energy deposited by the perturber. This paper demonstrates that this a...
9306020v1