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arXiv 2020年

作者： Chen, Zhilin Sohrabi, Foad Liu, Ya-Feng Yu, Wei The Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto TorontoONM5S 3G4 Canada The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

This paper considers a massive random access problem in which a large number of sporadically active devices wish to communicate with a base station (BS) equipped with massive multiple-input multiple-output (MIMO) antennas. Each device is preassigned a unique signature sequence, and the BS identifies the active devices by detecting which sequences are transmitted. This device activity detection problem can be formulated as a maximum likelihood estimation (MLE) problem for which the sample covariance matrix of the received signal is a sufficient statistic. The goal of this paper is to characterize the feasible set of problem parameters under which this covariance based approach is able to successfully recover the device activities in the massive MIMO regime. Through an analysis of the asymptotic behaviors of MLE via its associated Fisher information matrix, this paper derives a necessary and sufficient condition on the Fisher information matrix to ensure a vanishing probability of detection error as the number of antennas goes to infinity, based on which a numerical phase transition analysis is obtained. This condition is also examined from a perspective of covariance matching, which relates the phase transition analysis to a recently derived scaling law. Further, we provide a characterization of the distribution of the estimation error in MLE, based on which the error probabilities in device activity detection can be accurately predicted. Finally, this paper studies a random access scheme with joint device activity and data detection and analyzes its performance in a similar way. Copyright © 2020, The Authors. All rights reserved.

关键词： Maximum likelihood estimation

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Quantitative susceptibility atlas construction in montreal neurological institute space: Towards histological-consistent Iron-rich deep brain nucleus sub-region identification

Research Square

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Research Square 2021年

作者： He, Chenyu Guan, Xiaojun Zhang, Weimin Li, Jun Liu, Chunlei Wei, Hongjiang Xu, Xiaojun Zhang, Yuyao School of Information Science and Technology ShanghaiTech University 393 Huaxia Road Shanghai201210 China Department of Radiology Second Affiliated Hospital Zhejiang University School of Medicine 88 Jiefang Road Hangzhou Zhejiang 310009 China Electrical Engineering and Computer Science University of California at Berkeley BerkeleyCA94720 United States School of Biomedical Engineering Shanghai Jiao Tong University 800 Dongchuan Road Shanghai200030 China Institute of Medical Robotics Shanghai Jiao Tong University 800 Dongchuan Road Shanghai200030 China Shanghai Engineering Research Center of Intelligent Vision and Imaging ShanghaiTech University 393 Huaxia Road Shanghai201210 China

Iron-rich deep brain nuclei (DBN) of the human brain are involved in various motoric, emotional and cognitive brain functions. The abnormal iron alterations in the DBN are closely associated with multiple neurological and psychiatric diseases. Quantitative susceptibility mapping (QSM) provides the spatial distribution of tissue magnetic susceptibility in the human brain. Compared to traditional structural imaging, QSM has superiority for imaging the iron-rich DBN owing to the susceptibility difference existing between brain tissues. In this study, we construct a Montreal Neurological institute (MNI) space unbiased QSM human brain atlas via group-wise registration from 100 healthy subjects aged 19-29 years. The atlas construction process is guided by hybrid images that fused from multi-modal Magnetic Resonance Images (MRI), thus named as Multi-modal-fused magnetic Susceptibility (MuSus-100) atlas. The high-quality susceptibility atlas provides extraordinary image contrast between iron-rich DBN with their surroundings. Parcellation maps of DBN and their sub-regions that are highly related to neurological and psychiatric pathology are then manually labeled based on the atlas set with the assistance of an image border-enhancement process. Especially, the bilateral thalamus is delineated into 64 detailed sub-regions referring to the Schaltenbrand and Wahren stereotactic atlas. To our best knowledge, the histological-consistent thalamic nucleus parcellation map is well defined for the first time in MNI space. Comparing with existing atlases emphasized on DBN parcellation, the newly proposed atlas outperforms on atlas-guided individual brain image DBN segmentation accuracy and robustness. Moreover, we apply the proposed DBN parcellation map to conduct detailed identification of the pathology-related iron content alterations in subcortical nuclei for Parkinson Disease (PD) patients. We envision that the MuSus-100 atlas could play a crucial role in improving the accuracy of

关键词： Brain

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Roadmap for Optical Tweezers

arXiv

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arXiv 2022年

作者： Volpe, Giovanni Maragò, Onofrio M. Rubinzstein-Dunlop, Halina Pesce, Giuseppe Stilgoe, Alexander B. Volpe, Giorgio Tkachenko, Georgiy Truong, Viet Giang Chormaic, Síle Nic Kalantarifard, Fatemeh Elahi, Parviz Käll, Mikael Callegari, Agnese Marqués, Manuel I. Neves, Antonio A.R. Moreira, Wendel L. Fontes, Adriana Cesar, Carlos L. Saija, Rosalba Saidi, Abir Beck, Paul Eismann, Jörg S. Banzer, Peter Fernandes, Thales F.D. Pedaci, Francesco Bowen, Warwick P. Vaippully, Rahul Lokesh, Muruga Roy, Basudev Thalhammer, Gregor Ritsch-Marte, Monika García, Laura Pérez Arzola, Alejandro V. Castillo, Isaac Pérez Argun, Aykut Muenker, Till M. Vos, Bart E. Betz, Timo Cristiani, Ilaria Minzioni, Paolo Reece, Peter J. Wang, Fan McGloin, David Ndukaife, Justus C. Quidant, Romain Roberts, Reece P. Laplane, Cyril Volz, Thomas Gordon, Reuven Hanstorp, Dag Marmolejo, Javier Tello Bruce, Graham D. Dholakia, Kishan Li, Tongcang Brzobohatý, Oto Simpson, Stephen H. Zemánek, Pavel Ritort, Felix Roichman, Yael Bobkova, Valeriia Wittkowski, Raphael Denz, Cornelia Kumar, G.V. Pavan Foti, Antonino Donato, Maria Grazia Gucciardi, Pietro G. Gardini, L. Bianchi, G. Kashchuk, A. Capitanio, M. Paterson, Lynn Jones, P.H. Berg-Sørensen, Kirstine Barooji, Younes F. Oddershede, Lene B. Pouladian, Pegah Preece, Daryl Adiels, Caroline Beck De Luca, Anna Chiara Magazzù, A. Ciriza, D. Bronte Iatì, M.A. Swartzlander, Grover A. Department of Physics University of Gothenburg Gothenburg41296 Sweden CNR IPCF Istituto per i Processi Chimico-Fisici Messina Italy ARC CoE for Engineered Quantum Systems School of Mathematics and Physics The University of Queensland Australia Department of Chemistry University College London 20 Gordon Street LondonWC1H 0AJ United Kingdom Dipartimento di Fisica Università degli studi di Napoli Federico II Italy Okinawa Institute of Science and Technology Graduate University Japan Department of Health Technology Technical University of Denmark Lyngby Denmark Physics Department Boğaziçi University Istanbul Turkey Chalmers University of Technology Gothenburg Sweden Departamento de Física de Materiales IFIMAC Instituto Nicolás Cabrera Universidad Autónoma de Madrid Spain Santo André São Paulo Brazil Tratamento de dados geofísicos Tecnologia e processamento de geologia e geofísica Exploração Petrobras - Petróleo Brasileiro S.A. Rio de Janeiro Rio de Janeiro Brazil Pernambuco Recife Brazil Ceará Fortaleza Brazil Campinas São Paulo Brazil Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra Università di Messina Italy Institute of Optics Information and Photonics University Erlangen-Nuremberg Staudtstr. 7/B2 ErlangenD-91058 Germany Max Planck Institute for the Science of Light Staudtstr. 2 ErlangenD-91058 Germany Institute of Physics University of Graz NAWI Graz Universitätsplatz 5 Graz8010 Austria Centre de Biologie Structurale CNRS INSERM Univ.Montpellier France Indian Institute of Technology Madras India Institute for Biomedical Physics Medical University of Innsbruck Austria Instituto de Física Universidad Nacional Autónoma de México Ciudad de MéxicoC. P. 04510 Mexico Departamento de Física Universidad Autónoma Metropolitana-Iztapalapa San Rafael Atlixco 186 Ciudad de México09340 Mexico Third Institute of Physics - Biophysics Georg August University Göttingen Germany Department of Electrical

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nanoparticle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration. Copyright © 2022, The Authors. All rights reserved.

关键词： Optical tweezers

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Multi-objective predictive taxi dispatch via network flow optimization∗

arXiv

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arXiv 2020年

作者： Kim, Beomjun Kim, Jeongho Huh, Subin You, Seungil Yang, Insoon Department of Electrical and Computer Engineering Seoul National University Seoul08826 Korea Republic of Institute of New Media and Communications Seoul National University Seoul08826 Korea Republic of Automation and Systems Research Institute Seoul National University Seoul08826 Korea Republic of Kakao Mobility Gyeonggi-do13494 Korea Republic of

In this paper, we discuss a large-scale fleet management problem in a multi-objective setting. We aim to seek a receding horizon taxi dispatch solution that serves as many ride requests as possible while minimizing the cost of relocating vehicles. To obtain the desired solution, we first convert the multi-objective taxi dispatch problem into a network flow problem, which can be solved using the classical minimum cost maximum flow (MCMF) algorithm. We show that a solution obtained using the MCMF algorithm is integer-valued;thus, it does not require any additional rounding procedure that may introduce undesirable numerical errors. Furthermore, we prove the time-greedy property of the proposed solution, which justifies the use of receding horizon optimization. For computational efficiency, we propose a linear programming method to obtain an optimal solution in near real time. The results of our simulation studies using the real-world data for the metropolitan area of Seoul, South Korea indicate that the performance of the proposed predictive method is almost as good as that of the oracle that foresees the future. Copyright © 2020, The Authors. All rights reserved.

关键词： Linear programming

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STROBE-X Mission Overview

arXiv

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arXiv 2024年

作者： Ray, Paul S. Roming, Peter W.A. Argan, Andrea Arzoumanian, Zaven Ballantyne, David R. Bogdanov, Slavko Bonvicini, Valter Brandt, Terri J. Bursa, Michal Cackett, Edward M. Chakrabarty, Deepto Christophersen, Marc Coderre, Kathleen M. De Geronimo, Gianluigi Del Monte, Ettore DeRosa, Alessandra Dietz, Harley R. Evangelista, Yuri Feroci, Marco Ford, Jeremy J. Froning, Cynthia Fryer, Christopher L. Gendreau, Keith C. Goldstein, Adam Gonzalez, Anthony H. Hartmann, Dieter Hernanz, Margarita Hutcheson, Anthony Zand, Jean in't Jenke, Peter Kennea, Jamie Lloyd-Ronning, Nicole M. Maccarone, Thomas J. Maes, Dominic Markwardt, Craig B. Michalska, Malgorzata Okajima, Takashi Patruno, Alessandro Persyn, Steven C. Phillips, Mark L. Prescod-Weinstein, Chanda Redfern, Jillian A. Remillard, Ronald A. Santangelo, Andrea Schwendeman, Carl L. Sleator, Clio Steiner, James Strohmayer, Tod E. Svoboda, Jiri Tenzer, Christoph Thompson, Steven P. Warwick, Richard W. Watts, Anna L. Wilson-Hodge, Colleen A. Wu, Xin Wulf, Eric A. Zampa, Gianluigi Space Science Division U.S. Naval Research Laboratory WashingtonDC20375 United States Southwest Research Institute San AntonioTX78238 United States NASA’s Goddard Space Flight Center GreenbeltMD20771 United States Columbia Astrophysics Laboratory Columbia University New YorkNY10027 United States Trieste TS Italy SRON Netherlands Institute for Space Research Niels Bohrweg 4 CA Leiden2333 Netherlands Astronomical Institute of the Czech Academy of Sciences Boční II 1401 Prague14100 Czech Republic Department of Physics & Astronomy Wayne State University DetroitMI48201 United States Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Department of Nuclear Engineering and Radiological Sciences Univeristy of Michigan Ann ArborMI United States INAF - Istituto di Astrofisica e Planetologia Spaziali Roma00133 Italy Los Alamos National Laboratory Los AlamosNM87545 United States Universities Space Research Association HuntsvilleAL35805 United States Department of Astronomy University of Florida GainesvilleFL32611 United States IEEC Campus UAB Carrer de Can Magrans s/n Bellaterra Barcelona08193 Spain University of Alabama in Huntsville HuntsvilleAL35805 United States Department of Astronomy and Astrophysics The Pennsylvania State University University ParkPA16802 United States Department of Physics & Astronomy Texas Tech University LubbockTX79409 United States Space Research Center Polish Academy of Sciences Warszawa Poland Department of Physics and Astronomy University of New Hampshire DurhamNH03824 United States Harvard-Smithsonian Center for Astrophysics CambridgeMA02138 United States Eberhard Karls Universität Tübingen Germany Anton Pannekoek Institute for Astronomy University of Amsterdam Amsterdam1090GE Netherlands Astrophysics Branch NASA’s Marshall Space Flight Center HuntsvilleAL35812 United States Department of Nuclear and Particle Physics Univ

We give an overview of the science objectives and mission design of the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X) observatory, which has been proposed as a NASA probe-class (∼$1.... 详细信息

关键词： NASA

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Systematic Resource Allocation in Cloud RAN with Caching as a Service under Two Timescales

Systematic Resource Allocation in Cloud RAN with Caching as ...

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作者： Tang, Jianhua Quek, Tony Q. S. Chang, Tsung-Hui Shim, Byonghyo Hunan Provincial Key Laboratory of Intelligent Computing and Language Information Processing College of Information Science and Engineering Hunan Normal University Changsha410081 China Institute of New Media and Communications Department of Electrical and Computer Engineering Seoul National University Seoul08826 Korea Republic of Information Systems Technology and Design Pillar Singapore University of Technology and Design Singapore487372 Singapore Department of Electronic Engineering Kyung Hee University Yongin17104 Korea Republic of School of Science and Engineering Chinese University of Hong Kong Shenzhen518172 China Shenzhen Research Institute of Big Data Shenzhen518172 China Department of Electrical and Computer Engineering Institute of New Media and Communications Seoul National University Seoul08826 Korea Republic of

Recently, cloud radio access network (C-RAN) with caching as a service (CaaS) was proposed to merge the functionalities of communication, computing, and caching (CCC) together. In this paper, we dissect the interactions of CCC in C-RAN with CaaS from two dimensions: physical resource dimension and time dimension. In the physical resource dimension, we identify how to segment the baseband unit (BBU) pool resources (i.e., computation and storage) into different types of virtual machines (VMs). In the time dimension, we address how the long-term resource segmentation in the BBU pool impacts on the short-term transmit beamforming at the remote radio heads. We formulate the problem as a stochastic mixed-integer nonlinear programming (SMINLP) to minimize the system cost, including the server cost, VM cost and wireless transmission cost. After a series of approximation, including sample average approximation, successive convex approximation, and semidefinite relaxation, the SMINLP is approximated as a global consensus problem. The alternating direction method of multipliers (ADMM) is utilized to obtain the solution in a parallel fashion. Simulation results verify the convergence of our proposed algorithm, and also confirm that the proposed scheme is more cost-saving than that without considering the integration of CCC. © 1972-2012 IEEE.

关键词： Integer programming

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Blind identification of stochastic block models from dynamical observations

arXiv

引用

arXiv 2019年

作者： Schauby, Michael T. Segarraz, Santiago Tsitsiklisx, John N. Institute for Data Systems and Society Massachusetts Institute of Technology United States Department of Engineering Science University of Oxford Department of Electrical and Computer Engineering Rice University United States Laboratory of Information and Decision Systems Massachusetts Institute of Technology United States

We consider a blind identification problem in which we aim to recover a statistical model of a network without knowledge of the network's edges, but based solely on nodal observations of a certain process. More concretely, we focus on observations that consist of snapshots of a diffusive process that evolves over the unknown network. We model the network as generated from an independent draw from a latent stochastic block model (SBM), and our goal is to infer both the partition of the nodes into blocks, as well as the parameters of this SBM. We present simple spectral algorithms that provably solve the partition recovery and parameter estimation problems with high accuracy. Our analysis relies on recent results in random matrix theory and covariance estimation, and associated concentration inequalities. We illustrate our results with several numerical experiments. Copyright © 2019, The Authors. All rights reserved.

关键词： Blind equalization

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CMOS-compatible multi-band plasmonic TE-pass polarizer

arXiv

引用

arXiv 2022年

作者： Abadía, Nicolás Saber, Md. Ghulam Bello, Frank Samani, Alireza El-Fiky, Eslam Wang, Yun Donegan, John F. Plant, David V. Photonic Systems Group Department of Electrical and Computer Engineering McGill University 3480 University Street MontréalH3A 0E9 Canada Photonics Group School of Physics Trinity College Dublin 2 Ireland Trinity College Dublin Dublin 2 Ireland Amber Research Centre Trinity College Dublin Dublin 2 Ireland School of Physics and Astronomy Cardiff University Queen's Buildings The Parade CardiffCF24 3AA United Kingdom Institute for Compound Semiconductors Cardiff University Queen's Buildings The Parade CardiffCF24 3AA United Kingdom

A CMOS-compatible plasmonic TE-pass polarizer capable of working in the O, E, S, C, L, and U bands is numerically analyzed. The device is based on an integrated hybrid plasmonic waveguide (HPW) with a segmented metal design. The segmented metal will avoid the propagation of the TM mode, confined in the slot of the HPW, while the TE fundamental mode will pass. The TE mode is not affected by the metal segmentation since it is confined in the core of the HPW. The concept of the segmented metal can be exploited in a plasmonic circuit with HPWs as the connecting waveguides between parts of the circuit and in a silicon photonics circuit with strip or slab waveguides connecting the different parts of the circuit. Using 3D FDTD simulations, it is shown that for a length of 5.5 μm the polarization extinction ratios are better than 20 dB and the insertion losses are less than 1.7 dB over all the optical communication bands. © 2022, CC BY.

关键词： Metals

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Primal-dual optimization methods for large-scale and distributed data analytics

arXiv

引用

arXiv 2019年

作者： Jakovetić, Dušan Bajović, Dragana Xavier, João Moura, José M.F. Faculty of Sciences University of Novi Sad Novi Sad Serbia Faculty of Technical Sciences University of Novi Sad Novi Sad Serbia Instituto Superior Tećnico Universidade de Lisboa Institute for Systems and Robotics Laboratory for Robotics and Engineering Systems Lisbon Portugal Department of Electrical and Computer Engineering Carnegie Mellon University PittsburghPA United States

The augmented Lagrangian method (ALM) is a classical optimization tool that solves a given "difficult" (constrained) problem via finding solutions of a sequence of "easier" (often unconstrained) sub-problems with respect to the original (primal) variable, wherein constraints satisfaction is controlled via the so-called dual variables. ALM is highly flexible with respect to how primal sub-problems can be solved, giving rise to a plethora of different primal-dual methods. The powerful ALM mechanism has recently proved to be very successful in various large scale and distributed applications. In addition, several significant advances have appeared, primarily on precise complexity results with respect to computational and communication costs in the presence of inexact updates and design and analysis of novel optimal methods for distributed consensus optimization. We provide a tutorial-style introduction to ALM and its analysis via control-theoretic tools, survey recent results, and provide novel insights in the context of two emerging applications: federated learning and distributed energy trading. Copyright © 2019, The Authors. All rights reserved.

关键词： Constrained optimization

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Reciprocal collision avoidance for general nonlinear agents using reinforcement learning

arXiv

引用

arXiv 2019年

作者： Li, Hao Weng, Bowen Gupta, Abhishek Pan, Jia Zhang, Wei Department of Electrical and Computer Engineering Ohio State University ColumbusOH United States Department of Computer Science University of Hong Kong Hong Kong SUSTech Institute of Robotics Southern University of Science and Technology China

Finding feasible and collision-free paths for multiple nonlinear agents is challenging in the decentralized scenarios due to limited available information of other agents and complex dynamics constraints. In this paper, we propose a fast multi-agent collision avoidance algorithm for general nonlinear agents with continuous action space, where each agent observes only positions and velocities of nearby agents. To reduce online computation, we first decompose the multiagent scenario and solve a two agents collision avoidance problem using reinforcement learning (RL). When extending the trained policy to a multi-agent problem, safety is ensured by introducing the optimal reciprocal collision avoidance (ORCA) as linear constraints and the overall collision avoidance action could be found through simple convex optimization. Most existing RL-based multi-agent collision avoidance algorithms rely on the direct control of agent velocities. In sharp contrasts, our approach is applicable to general nonlinear agents. Realistic simulations based on nonlinear bicycle agent models are performed with various challenging scenarios, indicating a competitive performance of the proposed method in avoiding collisions, congestion and deadlock with smooth trajectories. Copyright © 2019, The Authors. All rights reserved.

关键词： Multi agent systems

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