检索结果-内蒙古大学图书馆

Spin-phonon interaction in yttrium iron garnet

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Olsson, Kevin S. Choe, Jeongheon Rodriguez-Vega, Martin Khalsa, Guru Benedek, Nicole A. Fang, Bin Zhou, Jianshi Fiete, Gregory A. Li, Xiaoqin Department of Physics Center of Complex Quantum Systems The University of Texas at Austin AustinTX78712 United States Center for Dynamics and Control of Materials The University of Texas at Austin AustinTX78712 United States Department of Physics Northeastern University BostonMA02115 United States Department of Materials Science and Engineering Cornell University IthacaNY14853 United States Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Computer and Electrical Engineering University of Maryland College ParkMD20740 United States

Spin-phonon interaction is an important channel for spin and energy relaxation in magnetic insulators. Understanding this interaction is critical for developing magnetic insulator-based spintronic devices. Quantifying this interaction in yttrium iron garnet (YIG), one of the most extensively investigated magnetic insulators, remains challenging because of the large number of atoms in a unit cell. Here, we report temperature-dependent and polarization-resolved Raman measurements in a YIG bulk crystal. We first classify the phonon modes based on their symmetry. We then develop a modified mean-field theory and define a symmetry-adapted parameter to quantify spin-phonon interaction in a phononmode specific way for the first time in YIG. Based on this improved mean-field theory, we discover a positive correlation between the spin-phonon interaction strength and the phonon frequency. Copyright © 2021, The Authors. All rights reserved.

关键词： Phonons

Reliability evaluation of highly reliable computer control systems for energy generation, transmission and distribution

学校读者我要写书评

暂无评论

EUROPEAN TRANSACTIONS ON electrical POWER 1996年第2期6卷 111-118页

作者： Kochs, HD Dieterle, W Dittmar, E [?]Prof. Dr.-Ing. Hans-Dieter Kochs (1943) VDE is head of the Department of Computer Science and Information Processing Systems at the Gerhard Mercator-University of Duisburgl Germany. He received the Dip1.-Ing. degree in Electrical Engineering and the Dr.-Ing. degree from the RWTH Aached Germany in 1972 and 1976 respectively. From 1979 to 1991 he was system engineer and division leader in the areas of R & D of highly-reliable large-scale control and information systems (AEGIDaimler FAG-Kugelfischer). Since 199 1 he has been Professor at the University of Duisburg. His current R & D areas are reliability safety and fault tolerance of technical systems especially automation systems and hybridknowledge based systems including fuzzy-logic and neural networks. (Gerhard-Menxitor-University-GH Duisburg FB 71FG 10 Lotharstr. 1 D-47048 Duisburg T +49203/379-2204 Fax +49203I379-2205)

The paper presents the results of an application-based reliability study of distributed computer control systems with very high reliability demand, e.g. for supervision and control of power plants and energy distribution systems. A reliability classification scheme is presented and typical redundant control system structures are evaluated and classified due to their system reliability Special focus is placed on assessing the influence of the communication system on total system reliability.

关键词：

Roles of neural and evolutionary computing in intelligent software systems

学校读者我要写书评

暂无评论

British Telecom technology journal

British Telecom technology journal 1996年第4期14卷 46-54页

作者： Tsui, K.C. Azvine, B. Plumbley, M. Hong Kong Polytechnic University of Essex Kings College University of London BT Laboratories Manchester University Dynamics and Control Research Group Engineering Department Manchester University Contr. and Instrum. Research Group Staffordshire University Intelligent Systems Research Group Churchill College Cambridge United Kingdom Thorn-EMI Ctrl. Res. Laboratories Cambridge Univ. Eng. Department Centre for Neural Networks King's College London Department of Computer Science Electron. and Electrical Engineering King's College London United Kingdom European Neural Network Society

This paper describes two computing paradigms known as neural computing and evolutionary computing, and their potential contribution to building intelligent software systems. The paper begins by giving a brief introduction to the origins of each paradigm. Then two sections introduce the basic principles, and identify the role of each paradigm in intelligent system design. Each section ends with a number of applications that have been or are being investigated. These include connection admission control, modem communication, adaptive model-based control, face and handwriting recognition, frequency assignment, help-desk scheduling, financial time-series prediction, face recognition and evolving agent behavior. A section introduces the idea of using communications theory to design neural networks and the paper concludes with the authors' views on the future of neural and evolutionary computing for intelligent software systems.

关键词： Artificial intelligence

State Estimation of LPV Discrete-Time Systems with Application to Output Feedback Stabilization

学校读者我要写书评

暂无评论

State Estimation of LPV Discrete-Time Systems with Applicati...

IEEE Annual Conference on Decision and control

作者： K. Chaib-Draa A. Zemouche R. Rajamani Y. Wang F. Bedouhene H. R. Karimi T. M. Laleg-Kirati University of Luxembourg Belval Luxembourg CRAN CNRS UMR 7039 Université de Lorraine France Laboratory for Innovations in Sensing Estimation and Control University of Minnesota Minneapolis USA Auris Health Inc. Redwood City CA USA Laboratoire de Mathématiques Pures et Appliquées Université Mouloud Mammeri de Tizi-Ouzou Algeria Department of Mechanical Engineering Politecnico di Milano Milan Italy Department of Computer Electrical and Mathematical Science an-dEngineering KAUST Saudi Arabia

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

This paper deals with new finite-time estimation algorithms for Linear Parameter Varying (LPV) discrete-time systems and their application to output feedback stabilization. Two exact finite-time estimation schemes are proposed. The first one provides a direct and explicit estimation algorithm based on the use of delayed outputs, while the second one uses two combined asymptotic observers, connected by a condition of invertibility of a certain time-varying matrix, to recover in a finite-time the solution of the LPV system. Furthermore, a stabilization strategy is proposed as an extension. This strategy, called Two Connected Observers Feedback (2-COF) stabilization method, is based on the use of the two combined observers based estimation algorithm.

关键词： Observers State estimation Output feedback Nonlinear systems control system synthesis Asymptotic stability Discrete-time systems Time-varying systems

High-quality Thermal Gibbs Sampling with Quantum Annealing Hardware

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Nelson, Jon Vuffray, Marc Lokhov, Andrey Y. Albash, Tameem Coffrin, Carleton Center for Non Linear Studies Los Alamos National Laboratory Los AlamosNM United States Advanced Network Science Initiative Los Alamos National Laboratory Los AlamosNM United States Theoretical Division Los Alamos National Laboratory Los AlamosNM United States Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM United States Department of Physics and Astronomy Center for Quantum Information and Control University of New Mexico AlbuquerqueNM United States

Quantum Annealing (QA) was originally intended for accelerating the solution of combinatorial optimization tasks that have natural encodings as Ising models. However, recent experiments on QA hardware platforms have demonstrated that, in the operating regime corresponding to weak interactions, the QA hardware behaves like a noisy Gibbs sampler at a hardware-specific effective temperature. This work builds on those insights and identifies a class of small hardware-native Ising models that are robust to noise effects and proposes a procedure for executing these models on QA hardware to maximize Gibbs sampling performance. Experimental results indicate that the proposed protocol results in high-quality Gibbs samples from a hardware-specific effective temperature. Furthermore, we show that this effective temperature can be adjusted by modulating the annealing time and energy scale. The procedure proposed in this work provides an approach to using QA hardware for Ising model sampling presenting potential new opportunities for applications in machine learning and physics simulation. Copyright © 2021, The Authors. All rights reserved.

关键词： Ising model

Squeezing-enhanced quantum sensing with quadratic optomechanics

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Zhang, Sheng-Dian Wang, Jie Zhang, Qian Jiao, Ya-Feng Zuo, Yun-Lan Özdemir, Şahin K. Qiu, Cheng-Wei Nori, Franco Jing, Hui Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China Department of Engineering Science and Mechanics Materials Research Institute Pennsylvania State University University Park State CollegePA16802 United States Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Saitama Wako-shi351-0198 Japan Physics Department The University of Michigan Ann ArborMI48109-1040 United States

Cavity optomechanical (COM) sensors, enhanced by quantum squeezing or entanglement, have become powerful tools for measuring ultra-weak forces with high precision and sensitivity. However, these sensors usually rely on linear COM couplings, a fundamental limitation when measurements of the mechanical energy are desired. Very recently, a giant enhancement of the signal-to-noise ratio was predicted in a quadratic COM system. Here we show that the performance of such a system can be further improved surpassing the standard quantum limit by using quantum squeezed light. Our approach is compatible with available engineering techniques of advanced COM sensors and provides new opportunities for using COM sensors in tests of fundamental laws of physics and quantum metrology applications. Copyright © 2022, The Authors. All rights reserved.

关键词： Quantum entanglement

Local Partial Zero-Forcing Combining for Cell-Free Massive MIMO Systems

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Zhang, Jiayi Zhang, Jing Björnson, Emil Ai, Bo The School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China The Frontiers Science Center for Smart High-Speed Railway System Beijing Jiaotong University Beijing100044 China The Department of Electrical Engineering Linköping University Linköping Sweden The Department of Computer Science KTH Royal Institute of Technology Kista Sweden The State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China The Frontiers Science Center for Smart High-Speed Railway System Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen China

Cell-free massive multiple-input multiple-output (MIMO) provides more uniform spectral efficiency (SE) for users (UEs) than cellular technology. The main challenge to achieve the benefits of cell-free massive MIMO is to realize signal processing in a scalable way. In this paper, we consider scalable full-pilot zero-forcing (FZF), partial FZF (PFZF), protective weak PFZF (PWPFZF), and local regularized ZF (LRZF) combining by exploiting channel statistics. We derive closed-form expressions of the uplink SE for FZF, PFZF, and PWPFZF combining with large-scale fading decoding over independent Rayleigh fading channels, taking channel estimation errors and pilot contamination into account. Moreover, we investigate the impact of the number of pilot sequences, antennas per AP, and APs on the performance. Numerical results show that LRZF provides the highest SE. However, PWPFZF is preferable when the number of pilot sequences is large and the number of antennas per AP is small. The reason is that PWPFZF has lower computational complexity and the SE expression can be computed in closed-form. Furthermore, we investigate the performance of PWPFZF combining with fractional power control and the numerical results show that it improves the performance of weak UEs and realizes uniformly good service for all UEs in a scalable fashion. Copyright © 2022, The Authors. All rights reserved.

关键词： Power control

Particle gibbs with ancestor sampling

学校读者我要写书评

暂无评论

The Journal of Machine Learning Research

The Journal of Machine Learning Research 2014年第1期15卷

作者： Kevin Murphy Bernhard Schölkopf Fredrik Lindsten Michael I. Jordan Thomas B. Schön Google Department of Engineering University of Cambridge Cambridge UK and Division of Automatic Control Linköping University Linköping Sweden Computer Science Division and Department of Statistics University of California Berkeley CA Department of Information Technology Uppsala University Uppsala Sweden

Particle Markov chain Monte Carlo (PMCMC) is a systematic way of combining the two main tools used for Monte Carlo statistical inference: sequential Monte Carlo (SMC) and Markov chain Monte Carlo (MCMC). We present a new PMCMC algorithm that we refer to as particle Gibbs with ancestor sampling (PGAS). PGAS provides the data analyst with an off-the-shelf class of Markov kernels that can be used to simulate, for instance, the typically high-dimensional and highly autocorrelated state trajectory in a state-space model. The ancestor sampling procedure enables fast mixing of the PGAS kernel even when using seemingly few particles in the underlying SMC sampler. This is important as it can significantly reduce the computational burden that is typically associated with using SMC. PGAS is conceptually similar to the existing PG with backward simulation (PGBS) procedure. Instead of using separate forward and backward sweeps as in PGBS, however, we achieve the same effect in a single forward sweep. This makes PGAS well suited for addressing inference problems not only in state-space models, but also in models with more complex dependencies, such as non-Markovian, Bayesian nonparametric, and general probabilistic graphical models.

关键词： Bayesian inference non-Markovian models particle Markov chain Monte Carlo sequential Monte Carlo state-space models

Reconstruction algorithm of the refractive index of a cylindrical object from the intensity measurements of the total field

学校读者我要写书评

暂无评论

Microwave and Optical Technology Letters 1998年第3期14卷

作者： Takashi Takenaka David J. N. Wall Haruyuki Harada Mitsuru Tanaka Department of Electrical Engineering and Computer Science Nagasaki University Nagasaki 852 Japan Department of Mathematics and Statistics University of Canterbury Christchurch 1 New Zealand Department of Control Engineering Kagoshima National College of Technology Kagoshima 899-51 Japan Department of Electrical and Electronic Engineering Oita University Oita 870-11 Japan

A reconstruction algorithm for determining the complex refractive index of the object from measurements of the intensity of the total field is presented. The algorithm is based on an optimization procedure. The simulated results show that the algorithm is very effective in reconstructing refractive index distributions to which the first-order Born approximation cannot be applied. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14, 182–188, 1997

关键词： inverse scattering problems phase problems cost functional conjugate-gradient method