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Planar chiral metasurfaces with maximal tunable chiroptical response driven by bound states in the continuum

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arXiv 2021年

作者： Shi, Tan Deng, Zi-Lan Geng, Guangzhou Zeng, Yixuan Hu, Guangwei Overvig, Adam Li, Junjie Qiu, Cheng-Wei Alù, Andrea Kivshar, Yuri S. Li, Xiangping Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics Technology Jinan University Guangzhou510632 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100191 China Department of Electrical and Computer Engineering National University of Singapore Kent Ridge 117583 Singapore Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Nonlinear Physics Center Australian National University CanberraACT2601 Australia

Optical metasurfaces with high-Q chiral resonances can boost light-matter interaction for various applications of chiral response for ultrathin, active, and nonlinear metadevices. Usually, such metasurfaces require sophisticated depth-resolved nanofabrication to realize subwavelength stereo-nanostructures, posing overwhelming challenges, especially in the short-wavelength range. Here, we suggest a novel planar design for chiral metasurfaces supporting bound states in the continuum (BICs) and demonstrate experimentally chiroptical responses with record-high Q-factors (Q=390) and near-perfect circular dichroism (CD=0.93) at optical frequencies. The symmetry-reduced meta-atoms are highly birefringent and support winding elliptical eigen-polarizations with opposite helicity surrounding the BIC polarization singularity, providing a convenient way for achieving maximal planar chirality tuned by either breaking in-plane symmetry or changing illumination direction. Such sharply resonant chirality realized in planar metasurfaces promises various practical applications in classical and quantum optics including chiral sensing, enantiomer selection, and chiral quantum emitters. © 2021, CC BY.

关键词： Dichroism

MULTI-TASK LEARNING WITH LOW-RANK MATRIX FACTORIZATION FOR HYPERSPECTRAL NONLINEAR UNMIXING

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MULTI-TASK LEARNING WITH LOW-RANK MATRIX FACTORIZATION FOR H...

IEEE International Geoscience and Remote Sensing Symposium

作者： Yuanchao Su Jun Li Hairong Qi Paolo Gamba Antonio Plaza Javier Plaza Guangdong Provincial Key Laboratory of Urbanization and Geo-simulation Sun Yat-sen University Guangzhou China Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN USA Department of Electrical Computer and Biomedical Engineering University of Pavia Italy Department of Technology of Computers and Communications University of Extremadura Caceres Spain

Nonlinear unmixing of hyperspectral images has been a very challenging research problem, as it needs to consider the physical interactions between the sunlight scattered by multiple materials. In this paper, we propose a new approach for nonlinear unmixing which is based on multi-task learning (MTL) with low-rank matrix factorization (LRMF). The proposed approach establishes two tasks to conduct the unmixing problem under a nonlinear mixing model. In the first task, we employ LRMF to obtain endmember signatures and their corresponding abundance fractions simultaneously. Then, the second task uses LRMF to solve interactions from multiple scattering. The effectiveness of the proposed method is verified by using real hyperspectral data. Compared with other state-of-the-art nonlinear unmixing algorithms, the proposed approach demonstrates very competitive performance.

关键词： Hyperspectral imaging Task analysis Scattering Matrix decomposition Linear programming Image reconstruction

Codes with Locality for Two Erasures

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Codes with Locality for Two Erasures

作者： Prakash, N. Lalitha, V. Balaji, S.B. Vijay Kumar, P. Indian Institute of Science Bengaluru560 012 India Signal Processing and Communications Research Centre International Institute of Information Technology Hyderabad500 032 India Department of Electrical Communication Engineering Indian Institute of Science Bengaluru560 012 India Department of Electrical Communication Engineering Indian Institute of Science Bengaluru560 012 India Intel Labs HillsboroOR97124 United States Department of Electrical and Computer Engineering University of Southern California Los AngelesCA United States

Codes with locality are a class of codes introduced by Gopalan et al. to efficiently repair a failed node, by minimizing the number of nodes contacted during repair. An [n,k] systematic code is said to have information locality r , if each message symbol can be recovered by accessing ≤q r other symbols. An [n,k] code is said to have all-symbol locality r , if each code symbol can be recovered by accessing ≤ r other symbols. In this paper, we consider a generalization of codes with all-symbol locality to the case of handling two erasures. We study codes with locality that can recover from two erasures via a sequence of two local, parity-check computations. We refer to these codes as sequential-recovery locally repairable codes (denoted by 2-seq LR codes). Earlier approaches to handling multiple erasures considered recovery in parallel;the sequential approach allows us to potentially construct codes with improved minimum distance. We derive an upper bound on the rate of 2-seq LR codes. We provide constructions based on regular graphs which are rate-optimal with respect to the derived bound. We also characterize the structure of any rate-optimal code. By studying the Generalized Hamming Weights of the dual code, we derive a recursive upper bound on the minimum distance of 2-seq LR codes. We also provide constructions of a family of codes based on Turán graphs, that are optimal with respect to this bound. We also present explicit distance-optimal Turán graph based constructions of 2-seq LR codes for certain parameters. Our approach also leads to a new bound on the minimum distance of codes with all-symbol locality for the single-erasure case. © 1963-2012 IEEE.

关键词： Recovery

Spectral and energy efficiency of IRS-assisted MISO communication with hardware impairments

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arXiv 2020年

作者： Zhou, Shaoqing Xu, Wei Wang, Kezhi Di Renzo, Marco Alouini, Mohamed-Slim National Mobile Communications Research Laboratory Southeast University Nanjing210096 China National Mobile Communications Research Laboratory Southeast University Nanjing210096 China Purple Mountain Laboratories Nanjing211111 China Department of Computer and Information Sciences Northumbria University Newcastle upon TyneNE1 8ST United Kingdom Université Paris-Saclay CNRS CentraleSupélec Laboratoire des Signaux et Systèmes Gif-sur-Yvette France Division of Computer Electrical and Mathematical Science and Engineering King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia

In this letter, we analyze the spectral and energy efficiency of an intelligent reflecting surface (IRS)-assisted multiple-input single-output (MISO) downlink system with hardware impairments. An extended error vector magnitude (EEVM) model is utilized to characterize the impact of radio-frequency (RF) impairments at the access point (AP) and phase noise is considered for the imperfect IRS. We show that the spectral efficiency is limited due to the hardware impairments even when the numbers of AP antennas and IRS elements grow infinitely large, which is in contrast with the conventional case with ideal hardware. Moreover, the performance degradation at high SNR is shown to be mainly affected by the AP hardware impairments rather than the phase noise of IRS. We further obtain the optimal transmit power in closed form for energy efficiency maximization. Simulation results are provided to verify these results. Copyright © 2020, The Authors. All rights reserved.

关键词： Energy efficiency

Risk-Sensitive Task Fetching and Offloading for Vehicular Edge Computing

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arXiv 2019年

作者： Batewela, Sadeep Liu, Chen-Feng Bennis, Mehdi Suraweera, Himal A. Hong, Choong Seon Nokia Networks Tampere33100 Finland Centre for Wireless Communications University of Oulu Oulu90014 Finland Centre for Wireless Communications University of Oulu Oulu90014 Finland Department of Computer Science and Engineering Kyung Hee University Yongin17104 Korea Republic of Department of Electrical and Electronic Engineering University of Peradeniya Peradeniya20400 Sri Lanka Department of Computer Science and Engineering Kyung Hee University Yongin17104 Korea Republic of

This letter studies an ultra-reliable low latency communication problem focusing on a vehicular edge computing network in which vehicles either fetch and synthesize images recorded by surveillance cameras or acquire the synthesized image from an edge computing server. The notion of risk-sensitive in financial mathematics is leveraged to define a reliability measure, and the studied problem is formulated as a risk minimization problem for each vehicle’s end-to-end (E2E) task fetching and offloading delays. Specifically, by resorting to a joint utility and policy estimation-based learning algorithm, a distributed risk-sensitive solution for task fetching and offloading is proposed. Simulation results show that our proposed solution achieves performance improvements up to 40% variance reduction and steeper distribution tail of the E2E delay over an averaged-based baseline. Copyright © 2019, The Authors. All rights reserved.

关键词： 5G mobile communication systems

A bibliometric study of the research area of videogames using *** database

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Procedia computer Science 2019年 162卷 737-744页

作者： Pablo García-Sánchez Antonio M. Mora Pedro A. Castillo Ignacio J. Pérez Department of Computer Science and Engineering Universtiy of Cádiz Escuela Superior de Ingeniería Avda. de la Universidad 10 Puerto Real 11519 Cádiz Spain Department of Signal Theory Telematics and Communications ETSIIT-CITIC University of Granada Calle Periodista Daniel Saucedo Aranda s/n Granada Spain Department of Computer Science and Computer Architecture ETSIIT-CITIC University of Granada Calle Periodista Daniel Saucedo Aranda s/n Granada Spain

Videogames are a very interesting area of research for fields as diverse as computer science, health, psychology or even social sciences. Every year a growing number of articles are published in different topics inside this field, so it is very convenient to study the different bibliometric data in order to consolidate the research efforts. Thus, the aim of this work is to conduct a study on the distribution of articles related to videogames in the different fields of research, as well as to measure their interest over time, to identify the sources, countries and authors with the highest scientific production. In order to carry out this analysis, the information system *** has been considered, since it covers a large number of documents and allows for easy downloading and analysis of datasets. According to the study, three countries are the most prolific in this area: USA, Canada and UK. The obtained results also indicate that the fields with the highest number of publications are Information and computer Sciences, Medical and Health Sciences, and Psychology and Cognitive Sciences, in this order. With regard to the impact of the publications, differences between the number of citations, and the number of Altmetric Attention Score, have been found.

关键词： videogames Dimensions.ai bibliometrics scientometrics

A crowdsourcing framework for on-device federated learning

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arXiv 2019年

作者： Pandey, Shashi Raj Tran, Nguyen H. Bennis, Mehdi Tun, Yan Kyaw Manzoor, Aunas Hong, Choong Seon Department of Computer Science and Engineering Kyung Hee University Yongin-si Gyeonggi-do17104 Korea Republic of School of Computer Science University of Sydney NSW2006 Australia Center for Wireless Communications University of Oulu Oulu90014 Finland

Federated learning (FL) rests on the notion of training a global model in a decentralized manner. Under this setting, mobile devices perform computations on their local data before uploading the required updates to improve the global model. However, when the participating clients implement an uncoordinated computation strategy, the difficulty is to handle the communication efficiency (i.e., the number of communications per iteration) while exchanging the model parameters during aggregation. Therefore, a key challenge in FL is how users participate to build a high-quality global model with communication efficiency. We tackle this issue by formulating a utility maximization problem, and propose a novel crowdsourcing framework to leverage FL that considers the communication efficiency during parameters exchange. First, we show an incentive-based interaction between the crowdsourcing platform and the participating client's independent strategies for training a global learning model, where each side maximizes its own benefit. We formulate a two-stage Stackelberg game to analyze such scenario and find the game's equilibria. Second, we formalize an admission control scheme for participating clients to ensure a level of local accuracy. Simulated results demonstrate the efficacy of our proposed solution with up to 22% gain in the offered reward. Copyright © 2019, The Authors. All rights reserved.

关键词： Crowdsourcing

Sign Language Translator using the Back Propagation Algorithm of an MLP

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Sign Language Translator using the Back Propagation Algorith...

IEEE International Conference on Future Internet of Things and Cloud Workshops (FiCloudW)

作者： Gaby Abou Haidar Roger Achkar Dian Salhab Antoine Sayah Fadi Jobran American University of Science and Technology Beirut Lebanon Department of Computer and Communications Engineering American University of Science and Technology AUST Beirut Lebanon American University of Science and Technology

ISBN: (数字)9781728144115

ISBN: (纸本)9781728144122

Although technology has been evolving rapidly in this information age, deaf/mute people still use sign language as their only way of communication. Using sign language as a communication tool can be beneficial among those who are familiar with this language, but the problem remains when communicating with the wider community. Sign Language Translator is the appropriate solution that enables deaf/mute people to communication fluently through technology in different languages. It is a combination of two gloves with the required sensors and a smart phone that contains the mobile application that translates the hand gestures into spoken words, is based on the Lebanese Sign Language; Artificial Neural Networks plays a big role in releasing the exact output.

关键词： backpropagation data gloves handicapped aids language translation mobile computing multilayer perceptrons natural language processing sign language recognition smart phones Smartphone Handicapped accessibility data gloves back propagation handicapped aids Multilayer perceptrons Natural Language Processing Mobile Computing interpreters sign language recognition CSRP3 gene Communication tools translator

Generalized Bussgang LMMSE Channel Estimator for One-Bit Massive MIMO Systems

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Generalized Bussgang LMMSE Channel Estimator for One-Bit Mas...

IEEE Global communications Conference

作者： Qian Wan Jun Fang Zhi Chen Hongbin Li National Key Laboratory on Communications University of Electronic Science and Technology of China Chengdu China Department of Electrical and Computer Engineering Stevens Institute of Technology Hoboken NJ USA

ISBN: (数字)9781728109626

ISBN: (纸本)9781728109633

We consider the problem of channel estimation for uplink massive multiple-input multiple-output systems, where one-bit analog-to-digital converters (ADCs) are used at the base station (BS) to quantize the received signal. In this paper, we study the problem of one-bit quantizer design when a Bussgang linear minimum mean square error (BLMMSE) estimator is used for channel estimation. We first extend the conventional Bussgang LMMSE estimator to the general nonzero threshold case. We then analyze the estimation performance of the generalized Bussgang LMMSE estimator and investigate the design of quantization thresholds. A gradient descent scheme is developed to search for optimal quantization thresholds. Simulation results show that, with carefully devised quantization thresholds, the generalized Bussgang LMMSE estimator can achieve a substantial performance improvement over the conventional Bussgang LMMSE estimator.

关键词： Covariance matrices Channel estimation MIMO communication Quantization (signal) Receiving antennas Estimation