检索结果-内蒙古大学图书馆

arXiv 2018年

作者： Davison, Elizabeth N. Aminzare, Zahra Leonard, Naomi Ehrich Dey, Biswadip Department of Mechanical and Aerospace Engineering Princeton University PrincetonNJ08540 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

We study the dynamics of a low-dimensional system of coupled model neurons as a step towards understanding the vastly complex network of neurons in the brain. We analyze the bifurcation structure of a system of two model neurons with unidirectional coupling as a function of two physiologically relevant parameters: the external current input only to the first neuron and the strength of the coupling from the first to the second neuron. Leveraging a timescale separation, we prove necessary conditions for multiple timescale phenomena observed in the coupled system, including canard solutions and mixed mode oscillations. For a larger network of model neurons, we present a sufficient condition for phase locking when external inputs are heterogeneous. Finally, we generalize our results to directed trees of model neurons with heterogeneous inputs.34A26, 34C15, 34C60, 34D15, 34E17, 37G05, 37G10, 92B20, 92C20 Copyright © 2018, The Authors. All rights reserved.

关键词： Bifurcation (mathematics)

来源：评论

学校读者我要写书评

暂无评论

Configurational entropy of magnetic skyrmions as an ideal gas

arXiv

引用

arXiv 2019年

作者： Zivieri, R. Tomasello, R. Chubykalo-Fesenko, O. Tiberkevich, V. Carpentieri, M. Finocchio, G. Department of Mathematical and Computer Sciences Physical Sciences and Earth Sciences University of Messina Messina98166 Italy Institute of Applied and Computational Mathematics Foundation for Research and Technology GR 700 13 Heraklion Crete Greece Instituto de Ciencia de Materiales de Madrid CSIC Cantoblanco Madrid Spain Department of Physics Oakland University RochesterMI48309 United States Department of Electrical and Information Engineering Politecnico di Bari Bari Italy

The study of thermodynamics of topological defects is an important challenge to understand their underlying physics. Among them, magnetic skyrmions have a leading role for their physical properties and potential applications in storage and neuromorphic computing. In this paper, the thermodynamic statistics of magnetic skyrmions is derived. It is shown that the skyrmion free energy can be modelled via a parabolic function and the diameters statistics obeys the Maxwell-Boltzmann distribution. This allows for making an analogy between the behavior of the distribution of skyrmion diameters statistics and the diluted gas Maxwell-Boltzmann molecules distribution at thermodynamical equilibrium. The calculation of the skyrmion configurational entropy, due to thermally-induced changes of size and shape of the skyrmion, is essential for the determination of thermal fluctuations of the skyrmion energy around its average value. These results can be employed to advance the field of skyrmionics. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetism

来源：评论

学校读者我要写书评

暂无评论

Discrete Boltzmann trans-scale modeling of high-speed compressible flows

引用

Physical Review E 2018年第5期97卷 053312-053312页

作者： Yanbiao Gan Aiguo Xu Guangcai Zhang Yudong Zhang Sauro Succi North China Institute of Aerospace Engineering Langfang 065000 China College of Mathematics and Informatics & FJKLMAA Fujian Normal University Fuzhou 350007 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing 100088 China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University Beijing 100871 China Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing 210094 China Center for Life Nano Science at La Sapienza Fondazione Istituto Italiano di Tecnologia Viale Regina Margherita 295 00161 Roma Italy Physics Department and Institute for Applied Computational Science John A. Paulson School of Applied Science and Engineering Harvard University Oxford Street 29 Cambridge Massachusetts 02138 USA

We present a general framework for constructing trans-scale discrete Boltzmann models (DBMs) for high-speed compressible flows ranging from continuum to transition regime. This is achieved by designing a higher-order discrete equilibrium distribution function that satisfies additional nonhydrodynamic kinetic moments. To characterize the thermodynamic nonequilibrium (TNE) effects and estimate the condition under which the DBMs at various levels should be used, two measures are presented: (i) the relative TNE strength, describing the relative strength of the (N+1)th order TNE effects to the Nth order one; (ii) the TNE discrepancy between DBM simulation and relevant theoretical analysis. Whether or not the higher-order TNE effects should be taken into account in the modeling and which level of DBM should be adopted is best described by the relative TNE intensity and/or the discrepancy rather than by the value of the Knudsen number. As a model example, a two-dimensional DBM with 26 discrete velocities at Burnett level is formulated, verified, and validated.

关键词： Classical statistical mechanics Classical transport Compressible flows Rarefied flows Nonequilibrium lattice models Lattice-Boltzmann methods

来源：评论

学校读者我要写书评

暂无评论

Joint quantum-state and measurement tomography with incomplete measurements

引用

Physical Review A 2018年第4期98卷 042318-042318页

作者： Adam C. Keith Charles H. Baldwin Scott Glancy E. Knill Applied and Computational Mathematics Division National Institute of Standards and Technology Boulder Colorado 80305 USA Department of Physics University of Colorado Boulder Colorado 80309 USA Center for Theory of Quantum Matter University of Colorado Boulder Colorado 80309 USA

Estimation of quantum states and measurements is crucial for the implementation of quantum information protocols. The standard method for each is quantum tomography. However, quantum tomography suffers from systematic errors caused by imperfect knowledge of the system. We present a procedure to simultaneously characterize quantum states and measurements that mitigates systematic errors by use of a single high-fidelity state preparation and a limited set of high-fidelity unitary operations. Such states and operations are typical of many state-of-the-art systems. For this situation we design a set of experiments and an optimization algorithm that alternates between maximizing the likelihood with respect to the states and measurements to produce estimates of each. In some cases, the procedure does not enable unique estimation of the states. For these cases, we show how one may identify a set of density matrices compatible with the measurements and use a semidefinite program to place bounds on the state's expectation values. We demonstrate the procedure on data from a simulated experiment with two trapped ions.

关键词： Quantum benchmarking Quantum information with trapped ions Quantum tomography

来源：评论

学校读者我要写书评

暂无评论

Numerical Analysis of QCW-Laser-Based Spot-Beam Crystallization of Si Films

Numerical Analysis of QCW-Laser-Based Spot-Beam Crystallizat...

引用

SID Symposium, Seminar, and Exhibition 2017, Display Week 2017

作者： Pann, Wenkai Song, Ruobing Suresh, Akhilesh K. Wong, Vernon K. Yu, Miao Choi, Insung Im, James S. Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New YorkNY United States

ISBN: (纸本)9781510848757

We are in the process of developing a new laser annealing method referred to as Spot-Beam Crystallization (SBC). The SBC method, which is potentially well suited for manufacturing advanced ultra-high-resolution AMOLED displays, is most effectively implemented using ultra-high- frequency quasi-continuous-wave (QCW) pulsed lasers. Conceptually and physically, this QCW-laser-based SBC (Q- SBC) approach builds on a thermally additive utilization of multiple short-lived ultra-high-frequency pulses, achieved via overlapped scanning of a small spot beam to incrementally and gradually heat and melt the beam-irradiated region. Using an updated version of a previously developed numerical program, we have carried out a simulation-based investigation to quantitatively examine and evaluate the basic tenets of the approach relevant specifically to partial-melting-based "ELA- like" crystallization of small-columnar-grained polycrystalline Si films using the Q-SBC method. The results from the effort to date as reported in this paper (1) largely confirm and validate the viability of the Q-SBC approach, and (2) suggest some specific directions for optimal development of the Q-SBC equipment and process. © 2017 SID.

关键词： Continuous wave lasers

来源：评论

学校读者我要写书评

暂无评论

Shape evolution of neutron-rich Mo106,108,110 isotopes in the triaxial degree of freedom

引用

Physical Review C 2020年第4期101卷 044311-044311页

作者： J. Ha T. Sumikama F. Browne N. Hinohara A. M. Bruce S. Choi I. Nishizuka S. Nishimura P. Doornenbal G. Lorusso P.-A. Söderström H. Watanabe R. Daido Z. Patel S. Rice L. Sinclair J. Wu Z. Y. Xu A. Yagi H. Baba N. Chiga R. Carroll F. Didierjean Y. Fang N. Fukuda G. Gey E. Ideguchi N. Inabe T. Isobe D. Kameda I. Kojouharov N. Kurz T. Kubo S. Lalkovski Z. Li R. Lozeva H. Nishibata A. Odahara Zs. Podolyák P. H. Regan O. J. Roberts H. Sakurai H. Schaffner G. S. Simpson H. Suzuki H. Takeda M. Tanaka J. Taprogge V. Werner O. Wieland Department of Physics and Astronomy Seoul National University Seoul 08826 Republic of Korea RIKEN Nishina Center 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan Department of Physics Tohoku University Aoba Sendai Miyagi 980-8578 Japan School of Computing Engineering and Mathematics University of Brighton Brighton BN2 4GJ United Kingdom Center for Computational Sciences University of Tsukuba Tsukuba 305-8577 Japan Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba 305-8571 Japan Department of Physics University of Surrey Guildford GU2 7XH United Kingdom National Physical Laboratory Teddington Middlesex TW11 0LW United Kingdom IRCNPC School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China Department of Physics Osaka University Toyonaka Osaka 560-0043 Japan Department of Physics University of York Heslington York YO10 5DD United Kingdom Department of Physics Peking University Beijing 100871 China Department of Physics University of Tokyo Hongo Bunkyo-ku Tokyo 113-0033 Japan Department of Physics University of Hong Kong Pokfulam Road Hong Kong IPHC CNRS/IN2P3 Université de Strasbourg 67037 Strasbourg France LPSC Université Grenoble-Alpes CNRS/IN2P3 F-38026 Grenoble Cedex France ILL 38042 Grenoble Cedex France GSI Helmholtzzentrum für Schwerionenforschung GmbH 64291 Darmstadt Germany Department of Physics University of Sofia 1164 Sofia Bulgaria CSNSM CNRS/IN2P3 Université Paris-Sud F-91405 Orsay Campus France Research Center for Nuclear Physics (RCNP) Osaka University Ibaraki Osaka 567-0047 Japan Departamento de Física Teórica Universidad Autónoma de Madrid E-28049 Madrid Spain Instituto de Estructura de la Materia CSIC E-28006 Madrid Spain A.W. Wright Nuclear Structure Laboratory Yale University New Haven Connecticut 06520 USA Institut für Kernphysik Technische Universität Darmstadt 64289 Darmstadt Germany INFN Sezione di Milano I-20133 Milano Italy

Background: Neutron-rich nuclei with mass number between 100 and 110 attract much attention, since several kinds of shapes, such as spherical, prolate, oblate, and triaxial shapes, are predicted. In particular, for neutron-rich Mo isotopes, different models predict different magnitudes and rigidity of triaxial deformation. Previous interpretations of experimental results based solely on low-lying 22+ states are insufficient to distinguish between the rigid triaxial shape, γ vibration, or γ-soft rotor.

关键词： Beta decay Collective levels Nuclear structure & decays Nucleon distribution 90 ≤ A ≤ 149

来源：评论

学校读者我要写书评

暂无评论

Algorithms of signal parameter estimation based on the theory of Compressive Sensing and their computer simulation

引用

Journal of physics: Conference Series 2020年第1期1479卷

作者： V I Parfenov D Y Golovanov N A Kunaeva Department of Physics Voronezh State University 1 Universitetskaya pl. Voronezh 394018 Russian Federation Department of Applied Mathematics Computational Science and Mechanics Voronezh State University 1 Universitetskaya pl. Voronezh 394018 Russian Federation Joint Stock Company «Concern «Sozvezdie» 14 Plehanovskaya Voronezh 394018 Russian Federation

The problem of estimating unknown signal parameters in the presence of noise is a classical problem in statistical radio engineering. There are many algorithms for solving this problem. Many of these algorithms are based on the use of well-known statistical optimality criteria in order to improve the estimation efficiency. Therefore, they acquire a high computational complexity. In this article, in order to reduce computational complexity, it is proposed to modernize the classical correlation algorithm based on the new Compressive Sensing theory, which has been actively developed in recent decades. The article presents a new simplified algorithm of signal parameters estimation, outlines operational speed benefits, and compares the efficiency of the proposed algorithm to the efficiency of the classical algorithm as well as some other algorithms. The proposed algorithm has also been compared to the classical one according to computational complexity. Practical implementation of the proposed algorithm requires much smaller number of arithmetical operations with some deterioration in unknown parameter estimation accuracy.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Strichartz estimates and wave equation in a conic singular space

arXiv

引用

arXiv 2018年

作者： Zhang, Junyong Zheng, Jiqiang Department of Mathematics Beijing Institute of Technology Beijing100081 China School of Mathematics Cardiff University CardiffCF24 4AG United Kingdom Institute of Applied Physics and Computational Mathematics Beijing100088 China

Consider the metric cone X = C(Y) = (0, ∞)r × Y with metric g = dr2 + r2h where the cross section Y is a compact (n - 1)-dimensional Riemannian manifold (Y, h). Let ∆g be the positive Friedrichs extension Laplacian on X and let ∆h be the positive Laplacian on Y, and consider the operator LV = ∆g +V0r-2 where V0 ∈ C∞(Y) such that ∆h + V0 + (n - 2)2/4 is a strictly positive operator on L2(Y). In this paper, we prove global-in-time Strichartz estimates without loss regularity for the wave equation associated with the operator LV . It verifies a conjecture in Wang [62, Remark 2.4] for wave equation. The range of the admissible pair is sharp and the range is influenced by the smallest eigenvalue of ∆h + V0 + (n - 2)2/4. To prove the result, we show a Sobolev inequality and a boundedness of a generalized Riesz transform in this setting. In addition, as an application, we study the wellposed theory and scattering theory for energy-critical wave equation with small data on this setting of dimension n ≥ *** Codes 42B37, 35Q40, 47J35 Copyright © 2018, The Authors. All rights reserved.

关键词： Wave equations

来源：评论

学校读者我要写书评

暂无评论

Emergent stability in complex network dynamics

arXiv

引用

arXiv 2020年

作者： Meena, Chandrakala Hens, Chittaranjan Acharyya, Suman Haber, Simcha Boccaletti, Stefano Barzel, Baruch Department of Mathematics Bar-Ilan University Ramat-Gan Israel Gonda Multidisciplinary Brain Research Center Bar-Ilan University Ramat-Gan Israel Chemical Engineering and Process Development CSIR-National Chemical Laboratory Pune India Indian Institute of Science Education and Research Maruthamala P. O Vithura Kerala Thiruvananthapuram695551 India Physics and Applied Mathematics Unit Indian Statistical Institute Kolkata India Center for Computational Natural Sciences and Bioinformatics International Institute of Information Technology Gachibowli Telangana Hyderabad500032 India Cnr Institute of Complex Systems Florence Italy Moscow Russia Universidad Rey Juan Carlos calle Tulipán s/n Madrid Móstoles28933 Spain Network Science Institute Northeastern University BostonMA United States

The stable functionality of networked systems is a hallmark of their natural ability to coordinate between their multiple interacting components. Yet, real world networks often appear random and highly irregular, raising the question of what are the naturally emerging organizing principles of complex system stability. The answer is encoded within the system's stability matrix - the Jacobian - but is hard to retrieve, due to the scale and diversity of the relevant systems, their broad parameter space, and their nonlinear interaction dynamics. Here, we introduce the dynamic Jacobian ensemble, which allows us to systematically investigate the fixed-point dynamics of a range of relevant network-based models. Within this ensemble, we find that complex systems exhibit discrete stability classes. These range from asymptotically unstable, where stability is unattainable, to sensitive, in which stability abides within a bounded range of the system's parameters. Alongside these two classes, we uncover a third asymptotically stable class, in which a sufficiently large and heterogeneous network acquires a guaranteed stability, independent of its microscopic parameters and of external perturbation. Hence, in this ensemble, two of the most ubiquitous characteristics of real-world networks - scale and heterogeneity - emerge as natural organizing principles to ensure fixed-point stability in the face of changing environmental conditions. © 2020, CC BY.

关键词： System stability

来源：评论

学校读者我要写书评

暂无评论

TGMin： A global-minimum structure search program based on a constrained basin-hopping algorithm

引用

Nano Research 2017年第10期10卷 3407-3420页

作者： Yafan Zhao Xin Chen Jun Li Institute of Applied Physics and Computational Mathematics Beijing 100088 China CAEP Software Center for High Performance Numerical Simulation Beijing 100088 China Department of Chemistry and Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education Tsinghua University Beijing 100084 China

In this article, we introduce Tsinghua Global Minimum （TGMin） as a new program for the global minimum searching of geometric structures of gas-phase or surface-supported atomic clusters, and the constrained basin-hopping （BH） algorithm implemented in this program. To improve the efficiency of the BH algorithm, several types of constraints are introduced to reduce the vast search space, including constraints on the random displacement step size, displacement of low-coordination atoms, and geometrical structure adjustment after displacement. The ultrafast shape-recognition （USR） algorithm and its variants are implemented to identify duplicate structures during the global minimum search. In addition to the Metropolis acceptance criterion, we also implemented a morphology-based constraint that confines the global minimum search to a specific type of morphology, such as planar or non-planar structures, which offers a strict divide-and-conquer strategy for the BH algorithm. These improvements are implemented in the TGMin program, which was developed over the past decade and has been used in a number of publications. We tested our TGMin program on global minimum structural searches for a number of metal and main-group clusters including C60, Au20 and B20 clusters. Over the past five years, the TGMin program has been used to determine the global minimum structures of a series of boron atomic clusters （such as [B26]^-, [B28]^-, [B30]^-, [B35]^-, [B36]^-, [B39]^-, [B40]^-, [MnB16]^-, [COB18]^-, [RhB18]^-, and [TaB20]^-）, metal-containing clusters Lin （n = 3-20）, Aug（CO）8^＋ and [Cr6O19]^2-. and the oxide-supported metal catalyst Au7/γ-Al2O3, as well as other isolated and surface-supported atomic clusters. In this article we present the major features of TGMin program and show that it is highly efficient at searching for global-minimum structures of atomic clusters in the gas phase and on various surface supports.

关键词： basin hopping ultrafast shape recognition global minimum search density functional theory cluster

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：