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Regular path-constrained time-optimal control problems in three-dimensional flow fields

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arXiv 2019年

作者： Chertovskih, R. Karamzin, D. Khalil, N.T. Pereira, F.L. Electrical and Computer Engineering Department Faculty of Engineering University of Porto 4200-465 Portugal Federal Research Center "Computer Science and Control" Russian Academy of Science Moscow Russia

This article concerns a class of time-optimal state constrained control problems with dynamics defined by an ordinary differential equation involving a three-dimensional steady flow vector field. The problem is solved via an indirect method based on the maximum principle in Gamkrelidze's form. The proposed computational method essentially uses a certain regularity condition imposed on the data of the problem. The property of regularity guarantees the continuity of the measure multiplier associated with the state constraint, and ensures the appropriate behavior of the corresponding numerical procedure which, in general, consists in computing the entire field of extremals for the problem in question. Several examples of vector fields are considered to illustrate the computational *** Codes 49K15, 49M05 Copyright © 2019, The Authors. All rights reserved.

关键词： Maximum principle

Atomically sharp interface enabled ultrahigh-speed, nonvolatile memory devices

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arXiv 2021年

作者： Wu, Liangmei Wang, Aiwei Shi, Jinan Yan, Jiahao Zhou, Zhang Bian, Ce Ma, Jiajun Ma, Ruisong Liu, Hongtao Chen, Jiancui Huang, Yuan Zhou, Wu Bao, Lihong Ouyang, Min Pennycook, Stephen J. Pantelides, Sokrates T. Gao, Hong-Jun Institute of Physics Chinese Academy of Sciences P. O. Box 603 Beijing100190 China Univ. of Chinese Acad. of Sciences and Cas Center for Excellence in Topological Quantum Computation Chinese Academy of Sciences P. O. Box 603 Beijing100190 China Songshan Lake Materials Laboratory Dongguan Guangdong523808 China Department of Physics College Park University of Maryland College ParkMD20742 United States Department of Materials Science and Engineering and Centre for Advanced 2D Materials National University of Singapore 117575 Singapore Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science Vanderbilt University NashvilleTN37235 United States

Development of memory devices with ultimate performance has played a key role in innovation of modern electronics. As a mainstream technology nonvolatile memory devices have manifested high capacity and mechanical reliability, however current major bottlenecks include low extinction ratio and slow operational speed. Although substantial effort has been employed to improve their performance, a typical hundreds of micro-or even milli-second write time remains a few orders of magnitude longer than their volatile counterparts. We have demonstrated nonvolatile, floating-gate memory devices based on van der Waals heterostructures with atomically sharp interfaces between different functional elements, and achieved ultrahigh-speed programming/erasing operations verging on an ultimate theoretical limit of nanoseconds with extinction ratio up to 1010. This extraordinary performance has allowed new device capabilities such as multi-bit storage, thus opening up unforeseen applications in the realm of modern nanoelectronics and offering future fabrication guidelines for device scale-up. Copyright © 2021, The Authors. All rights reserved.

关键词： Light extinction

Time-Varying Convex Optimization: Time-Structured Algorithms and Applications

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arXiv 2020年

作者： Simonetto, Andrea Dall’Anese, Emiliano Paternain, Santiago Leus, Geert Giannakis, Georgios B. Optimization and Control Group of IBM Research Ireland Dublin Ireland College of Engineering and Applied Science University of Colorado BoulderCO80309 United States Department of Electrical and Systems Engineering University of Pennsylvania Faculty of Electrical Mathematics and Computer Science Delft University of Technology Delft2628CD Netherlands Digital Technology Center University of Minnesota MinneapolisMN55455 United States

Optimization underpins many of the challenges that science and technology face on a daily basis. Recent years have witnessed a major shift from traditional optimization paradigms grounded on batch algorithms for medium-scale problems to challenging dynamic, time-varying, and even huge-size settings. This is driven by technological transformations that converted infrastructural and social platforms into complex and dynamic networked systems with even pervasive sensing and computing capabilities. The present paper reviews a broad class of state-of-the-art algorithms for time-varying optimization, with an eye to both algorithmic development and performance analysis. It offers a comprehensive overview of available tools and methods, and unveils open challenges in application domains of broad interest. The real-world examples presented include smart power systems, robotics, machine learning, and data analytics, highlighting domain-specific issues and solutions. The ultimate goal is to exempify wide engineering relevance of analytical tools and pertinent theoretical foundations. Copyright © 2020, The Authors. All rights reserved.

关键词： Data Analytics

Verification of application of ANN modelling in study of compressive behaviour of aluminium sponges

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engineering Transactions 2019年第2期67卷 271-288页

作者： Stręk, Anna M. Dudzik, Marek Kwiecień, Arkadiusz Wańczyk, Krzysztof Lipowska, Barbara Cracow University of Technology Faculty of Civil Engineering Institute of Structural Mechanics Warszawska 24 Kraków31-155 Poland Cracow University of Technology Faculty of Electrical and Computer Engineering Department of Traction and Traffic Control Warszawska 24 Kraków31-155 Poland Foundry Research Institute Center for Design and Prototyping Zakopiańska 73 Kraków30-418 Poland Institute of Ceramics and Building Materials Refractory Materials Division in Gliwice Toszecka 99 Gliwice44-100 Poland

This article presents a preliminary neural network analysis of the compressive behaviour of aluminium open-cell sponges and answers the question of whether this phenomenon can be modelled using artificial intelligence. The research consisted of two phases: first – compression experiments, which in turn provided data for the second phase – the artificial neural network (ANN) analysis. A two-argument function was proposed and tested using the gathered experimental data with a two-layer feedforward network. The determination coefficient R2 for linear correlation between targets and modelling outputs was chosen as the criterion for the assessment of the quality of modelling. The obtained values were R2 > 0.96, which shows that neural networks hold the capacity to address the characterisation of the mechanical response of aluminium open-cell sponges in compression. Additionally, the mean absolute relative error (MARE) and the mean square error (MSE) were also determined. © 2019, Polish Academy of Sciences. All rights reserved.

关键词： Aluminum

Single pixel fourier computed tomography

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Single pixel fourier computed tomography

Novel Techniques in Microscopy, NTM 2019

作者： Stockton, Patrick A. Wernsing, Keith A. Field, Jeff J. Squier, Jeff Bartels, Randy A. Department of Electrical and Computer Engineering Colorado State University United States Department of Biochemistry and Molecular Biology Colorado State University United States Microscope Imaging Network Foundational Core Facility Colorado State University United States School of Biomedical Engineering Colorado State University United States Center for Microintegrated Optics for Advanced Biological Control Department of Physics Colorado School of Mines United States

ISBN: (纸本)9781943580545

关键词： computerized tomography

Quantum repeaters: From quantum networks to the quantum internet

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arXiv 2022年

作者： Azuma, Koji Economou, Sophia E. Elkouss, David Hilaire, Paul Jiang, Liang Lo, Hoi-Kwong Tzitrin, Ilan NTT Basic Research Laboratories NTT Corporation 3-1 Morinosato Wakamiya Kanagawa Atsugi243-0198 Japan NTT Research Center for Theoretical Quantum Physics NTT Corporation 3-1 Morinosato-Wakamiya Kanagawa Atsugi243-0198 Japan Department of Physics Virginia Tech BlacksburgVA24061 United States QuTech Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Networked Quantum Devices Unit Okinawa Institute of Science and Technology Graduate University Okinawa Japan Quandela SAS 10 Boulevard Thomas Gobert Palaiseau91120 France Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60637 United States Quantum Bridge Technologies Inc. 100 College Street TorontoONM5G 1L5 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Center for Quantum Information and Quantum Control Department of Physics Department of Electrical & Computer Engineering University of Toronto TorontoM5S 3G4 Canada Department of Physics University of Toronto Toronto Canada

A quantum internet is the holy grail of quantum information processing, enabling the deployment of a broad range of quantum technologies and protocols on a global scale. However, numerous challenges exist before the quantum internet can become a reality. Perhaps the most crucial of these is the realization of a quantum repeater, an essential component in the long-distance transmission of quantum information. As the analog of a classical repeater, extender, or booster, the quantum repeater works to overcome loss and noise in the quantum channels comprising a quantum network. Here, we review the conceptual frameworks and architectures for quantum repeaters, as well as the experimental progress towards their realization. We also discuss the various near-term proposals to overcome the limits to the communication rates set by point-to-point quantum communication. Finally, we overview how quantum repeaters fit within the broader challenge of designing and implementing a quantum internet. Copyright © 2022, The Authors. All rights reserved.

关键词： Quantum optics

Comparing relaxation mechanisms in quantum and classical transverse-field annealing

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arXiv 2020年

作者： Albash, Tameem Marshall, Jeffrey Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States Department of Physics and Astronomy Center for Quantum Information and Control CQuIC University of New Mexico AlbuquerqueNM87131 United States QuAIL NASA Ames Research Center Moffett FieldCA94035 United States USRA Research Institute for Advanced Computer Science Mountain ViewCA94043 United States

Annealing schedule control provides new opportunities to better understand the manner and mechanisms by which putative quantum annealers operate. By appropriately modifying the annealing schedule to include a pause (keeping the Hamiltonian fixed) for a period of time, we show it is possible to more directly probe the dissipative dynamics of the system at intermediate points along the anneal and examine thermal relaxation rates, for example, by observing the re-population of the ground state after the minimum spectral gap. We provide a detailed comparison of experiments from a D-Wave device, simulations of the quantum adiabatic master equation and a classical analogue of quantum annealing, spin-vector Monte Carlo, and we observe qualitative agreement, showing that the characteristic increase in success probability when pausing is not a uniquely quantum phenomena. We find that the relaxation in our system is dominated by a single time-scale, which allows us to give a simple condition for when we can expect pausing to improve the time-to-solution, the relevant metric for classical optimization. In the system studied here, only for short pauses is there expected to be an improvement. Finally, we also explore in simulation the role of temperature whilst pausing as a means to better distinguish quantum and classical models of quantum annealers. Copyright © 2020, The Authors. All rights reserved.

关键词： Annealing

Doping-driven electronic and lattice dynamics in the phase-change material vanadium dioxide

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Physical Review B 2020年第11期102卷 115148-115148页

作者： Kannatassen Appavoo Joyeeta Nag Bin Wang Weidong Luo Gerd Duscher E. Andrew Payzant Matthew Y. Sfeir Sokrates T. Pantelides Richard F. Haglund, Jr. Department of Physics University of Alabama at Birmingham Birmingham Alabama 35294 USA Department of Physics and Astronomy Vanderbilt University Nashville Tennessee 37235 USA School of Chemical Biological and Materials Engineering University of Oklahoma Norman Oklahoma 73019 USA Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Key Laboratory of Artificial Structures and Quantum Control School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Department of Materials Science and Engineering University of Tennessee Knoxville Tennessee 37996 USA Center for Functional Nanomaterials Brookhaven National Laboratory Upton New York 11973 USA Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235 USA

Doping is generally understood as a strategy for including additional positive or negative charge carriers in a semiconductor, thereby tuning the Fermi level and changing its electronic properties in the equilibrium limit. However, because dopants also couple to all of the microscopic degrees of freedom in the host, they may also alter the nonequilibrium dynamical properties of the parent material, especially at large dopant concentrations. Here, we show how substitutional doping by tungsten at the 1 at. % level modifies the complex electronic and lattice dynamics of the phase-change material vanadium dioxide. Using femtosecond broadband spectroscopy, we compare dynamics in epitaxial thin films of pristine and tungsten-doped VO2 over the broadest wavelength and temporal ranges yet reported. We demonstrate that coupling of tungsten atoms to the host lattice modifies the early electron-phonon dynamics on a femtosecond timescale, altering in a counterintuitive way the ps-to-ns optical signatures of the phase transition. Density functional theory correctly captures the enthalpy difference between pristine and W-doped VO2 and shows how the dopant softens critical V-V phonon modes while introducing new phononic modes due to W-V bonds. While substitutional doping provides a powerful method to control the switching threshold and contrast of phase-change materials, determining how the dopant dynamically changes the broadband optical response is equally important for optoelectronics.

关键词： Electronic structure Lattice dynamics Phase transitions Phonons Photonics Functional materials Thin films Band structure methods Electron microscopy Epitaxy Femtosecond laser spectroscopy Film deposition First-principles calculations Laser techniques Monte Carlo methods Scanning electron microscopy

Opacity of Nondeterministic Transition Systems: A (Bi)Simulation Relation Approach

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Opacity of Nondeterministic Transition Systems: A (Bi)Simula...

作者： Zhang, Kuize Yin, Xiang Zamani, Majid ACCESS Linnaeus Center School of Electrical Engineering KTH Royal Institute of Technology Stockholm10044 Sweden Department of Automation Key Laboratory of System Control and Information Processing Shanghai Jiao Tong University Shanghai200240 China Computer Science Department University of Colorado Boulder BoulderCO80309 United States

In this paper, we propose several opacity-preserving (bi)simulation relations for nondeterministic transition systems (NTSs) in terms of initial-state opacity, current-state opacity, K-step opacity, and infinite-step opacity. We also show how one can leverage quotient constructions to compute such relations. As a result, although the opacity verification problem for infinite NTSs is generally undecidable, if one can find such an opacity-preserving relation from an infinite NTS to a finite one, the (lack of) opacity of the infinite NTS can be easily verified over the finite one, which is decidable. © 1963-2012 IEEE.

关键词： Opacity