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Topological photonics: Frontiers in robust light manipulation

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Reviews in Physics 2025年 13卷

作者： Zhang, Yongliang Sha, Wei E.I. Tsukerman, Igor State Key Laboratory of Semiconductor Physics and Chip Technologies Institute of Semiconductors Chinese Academy of Sciences Beijing100083 China College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Department of Electrical and Computer Engineering The University of Akron AkronOHOH 44325-3904 United States

Thermalization of Interacting Quasi-One-Dimensional Systems

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Physical Review Letters 2023年第3期130卷 030401-030401页

作者： Miłosz Panfil Sarang Gopalakrishnan Robert M. Konik Faculty of Physics University of Warsaw ul. Pasteura 5 02-093 Warsaw Poland Department of Physics The Pennsylvania State University University Park Pennsylvania 16802 USA Department of Electrical and Computer Engineering Princeton University Princeton New Jersey 08544 USA Condensed Matter Physics and Materials Science Division Brookhaven National Laboratory Upton New York 11973 USA

Many experimentally relevant systems are quasi-one-dimensional, consisting of nearly decoupled chains. In these systems, there is a natural separation of scales between the strong intrachain interactions and the weak interchain coupling. When the intrachain interactions are integrable, weak interchain couplings play a crucial part in thermalizing the system. Here, we develop a Boltzmann-equation formalism involving a collision integral that is asymptotically exact for any interacting integrable system, and apply it to develop a quantitative theory of relaxation in coupled Bose gases in the experimentally relevant Newton’s cradle setup. We find that relaxation involves a broad spectrum of timescales. We provide evidence that the Markov process governing relaxation at late times is gapless; thus, the approach to equilibrium is generally nonexponential, even for spatially uniform perturbations.

关键词： Cold atoms & matter waves Nonequilibrium statistical mechanics Bose gases Boltzmann theory

Compressed CPD-Based Channel Estimation and Joint Beamforming for RIS-Assisted Millimeter Wave Communications

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arXiv 2022年

作者： Zheng, Xi Fang, Jun Wang, Hongwei Wang, Peilan Li, Hongbin The National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu611731 China The Department of Electrical and Computer Engineering Stevens Institute of Technology HobokenNJ07030 United States

We consider the problem of channel estimation and joint active and passive beamforming for reconfigurable intelligent surface (RIS) assisted millimeter wave (mmWave) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. We show that, with a well-designed frame-based training protocol, the received pilot signal can be organized into a low-rank third-order tensor that admits a canonical polyadic decomposition (CPD). Based on this observation, we propose two CPD-based methods for estimating the cascade channels associated with different subcarriers. The proposed methods exploit the intrinsic low-rankness of the CPD formulation, which is a result of the sparse scattering characteristics of mmWave channels, and thus have the potential to achieve a significant training overhead reduction. Specifically, our analysis shows that the proposed methods have a sample complexity that scales quadratically with the sparsity of the cascade channel. Also, by utilizing the singular value decomposition-like structure of the effective channel, this paper develops a joint active and passive beamforming method based on the estimated cascade channels. Simulation results show that the proposed CPD-based channel estimation methods attain mean square errors that are close to the Cramér-Rao bound (CRB) and present a clear advantage over the compressed sensing-based method. In addition, the proposed joint beamforming method can effectively utilize the estimated channel parameters to achieve superior beamforming performance. Copyright © 2022, The Authors. All rights reserved.

关键词： Channel estimation

Surface Acoustic Wave Sensor Interrogation Using Goubau Waves

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Surface Acoustic Wave Sensor Interrogation Using Goubau Wave...

Antennas and Propagation Society International Symposium

作者： David W. Greve Jagannath Devkota Paul Ohodnicki Ruishu Wright Department of Electrical and Computer Engineering Carnegie Mellon U. Pittsburgh PA USA ORISE Faculty Fellow National Energy Technology Laboratory Pittsburgh PA National Energy Technology Laboratory Pittsburgh PA USA NETL Support Contractor Pittsburgh PA USA Department of Mechanical Engineering & Materials Science Swanson School of Engineering University of Pittsburgh Pittsburgh PA USA

Electromagnetic waves on single conductors (Goubau waves) are investigated for the interrogation of wireless sensors. A demonstration of interrogation of a surface acoustic wave (SAW) sensor is presented, followed by ...

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An Efficient Framework for the Solution of Contact Mechanics Problems in Soft Robotics

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An Efficient Framework for the Solution of Contact Mechanics...

IEEE International Conference on Soft Robotics (RoboSoft)

作者： Kevin Wandke Y Z Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana IL USA Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana IL USA Department of Nuclear Plasma and Radiological Engineering University of Illinois at Urbana-Champaign Urbana IL USA Department of Nuclear Engineering and Radiological Sciences University of Michigan Ann Arbor MI USA

Soft robots offer an exciting and novel alternative to traditional robots composed of rigid bodies. Many of the primary benefits soft robots have over more traditional robots result from their inherent compliance and their potential for low force interactions with their environments. Therefore, modeling soft robots requires the ability to accurately simulate contact mechanics. In this work, we present the solution of contact mechanics finite element problems specifically for soft robots in a MOOSE-based multiphysics simulation platform we developed, Kraken. The primary contributions of this work are threefold. Firstly, our implementations enable the modeling of additional types of contact critical to the simulation of soft robots. Next, we demonstrate how our new self contact method can be used to dramatically decrease the computational cost of contact modeling. Finally, we demonstrate the abilities of Kraken as a platform to simulate the complex interactions of soft robots and the environment.

关键词： Actuators Codes Computational modeling Friction Force Soft robotics Finite element analysis

Giant Thermomechanical Bandgap engineering in Quasi-two-dimensional Tellurium

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arXiv 2023年

作者： Hussain, Naveed Ahmed, Shehzad Tep, Hüseyin U. Ullah, Kaleem Shahzad, Khurram Wu, Hui Shcherbakov, Maxim R. Department of Electrical Engineering and Computer Science University of California Irvine IrvineCA92697 United States State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing100084 China College of Physics and Optoelectronic Engineering Shenzhen University Guangdong518060 China Micro and Nano-Technology Program School of Natural and Applied Sciences Middle East Technical University Ankara06800 Turkey Department of Electrical and Computer Engineering University of Delaware NewarkDE19711 United States Department of Physics Middle East Technical University Ankara06800 Turkey

Mechanical straining-induced bandgap modulation in two-dimensional (2D) materials has been confined to volatile and narrow modulation due to substrate slippage and poor strain transfer. We report the thermomechanical modulation of the inherent bandgap in quasi-2D tellurium nanoflakes (TeNFs) via non-volatile strain induction during hot-press synthesis. We leveraged the coefficient of thermal expansion (CTE) mismatch between TeNFs and growth substrates by maintaining a high-pressure enforced non-slip condition during thermal relaxation (623 to 300K) to achieve the optimal biaxial compressive strain of -4.6 percent in TeNFs/sapphire. This resulted in an enormous bandgap modulation of 2.3 eV, at a rate of up to ~600 meV/%, which is two-fold larger than reported modulation rate. Strained TeNFs display robust band-to-band radiative excitonic blue photoemission with an intrinsic quantum efficiency (IQE) of c.a. 79.9%, making it promising for energy efficient blue LEDs and nanolasers. Computational studies reveal that biaxial compressive strain inhibits exciton-exciton annihilation by evading van-Hove singularities, hence promoting radiative-recombination. Bandgap modulation by such nonvolatile straining is scalable to other 2D semiconductors for on-demand nano(opto)-electronics. Copyright © 2023, The Authors. All rights reserved.

关键词： Energy gap

Electron-induced chemistry and sputtering of volatile species from amorphous and crystalline water ice

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arXiv 2025年

作者： Mishra, Yogeshwar Nath Chandra, Sankhabrata Gudipati, Murthy S. Henderson, Bryana Hanstorp, Dag Yung, Yuk L. Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States Department of Physics University of Gothenburg GothenburgSE 41296 Sweden Division of Geological and Planetary Science California Institute of Technology PasadenaCA91125 United States Computer Electrical and Mathematical Sciences and Engineering Division KAUST Saudi Arabia

Electron irradiation of water-rich ices plays a significant role in initiating the chemical and physical processes on the surface of airless icy bodies in radiation environments such as Europa and Enceladus, as well as on the Moon, comets, and asteroids interacting with the solar wind. The sputtering process by electrons and ions leads to chemical modification and outgassing of their icy surfaces and the subsequent formation of a tenuous atmosphere. Though electron-sputtering yields are known to be lower compared to ion-sputtering yields, one needs to also account for their differential fluxes. Europa receives about 10 times more electron flux than proton flux, making electron-induced outgassing important to study and understand. Here, we report a rigorous experimental study of electron bombardment of Europa analog crystalline and amorphous pure water ices at 100 K under ultrahigh vacuum and compare our results with reported data in the literature to provide quantitative data for low-energy electron-induced chemistry and sputtering of water-ice. In our experiments, the electron-induced sputtering yields of all the gaseous species H2, O, OH, H2O, and O2 are investigated for electron energies lower than 2 keV in terms of partial pressure vs. time of irradiation. The effective averaged change in partial pressure of the desorbed species is converted to the number of sputtered atoms or molecules per second per cm2 from the ice, and then to the sputtering yields (number of species sputtered per electron). These values at different electron fluences (electrons/cm2) are then used to derive the number of atoms or molecules desorbed or sputtered per keV of incident electrons, to enable utilizing our data to quantify the contribution of electron-sputtering process towards the exospheric composition of Europa. Our data agrees well with the previously reported data for the sputtering of O2 and H2O yield for the amorphous ice. We also find that crystalline ice shows significantly

关键词： Electron irradiation

Screening cognitive impairment in patients with atrial fibrillation: A deep learning model based on retinal fundus photographs

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Heart Rhythm O2

Heart Rhythm O2 2025年第5期6卷 678-686页

作者： Wang, Zhen Li, Mingxiao Xia, Peng Jiang, Chao Shen, Ting Ma, Jiaming Bai, Yu Zhang, Suhui Lai, Yiwei Li, Sitong Xu, Hui Xu, Yang Ma, Tong Ju, Lie He, Liu Dong, Li Sang, Caihua Long, Deyong Chen, Yuzhong Du, Xin Ge, Zongyuan Dong, Jianzeng Wei, Wen-Bin Ma, Changsheng Department of Cardiology Beijing Anzhen Hospital Capital Medical University Beijing China Engineering Research Center of Medical Devices for Cardiovascular Diseases Ministry of Education Capital Medical University Beijing China National Clinical Research Center for Cardiovascular Diseases Beijing China Beijing Airdoc Technology Co. Ltd. Beijing China Department of Electrical and Computer Systems Engineering Faculty of Engineering Monash University Clayton Australia Yale School of Medicine New Haven Connecticut United States School of Clinical Medicine Peking Union Medical College and Chinese Academy of Medical Science Beijing China Beijing Tongren Eye Center Beijing Key Laboratory of Intraocular Tumor Diagnosis and Treatment Beijing Ophthalmology & Visual Sciences Key Lab Medical Artificial Intelligence Research and Verification Key Laboratory of the Ministry of Industry and Information Technology Beijing Tongren Hospital Capital Medical University Beijing China Monash e-Research Center Monash University Clayton Australia

Background: Patients with atrial fibrillation (AF) have a higher risk of cognitive impairment (CI). However, complexity of CI diagnosis and lack of simple screening approaches limited early screening and intervention of CI in AF patients. Objective: Our study aimed to develop deep learning models based on fundus photographs for easy screening of CI in AF patients. Methods: From May 2021 to April 2023, patients who completed fundus examination and cognitive function evaluation in the Chinese Atrial Fibrillation Registry Study were included. The training and validation sets were randomly split at an 8:2 ratio. Participants from the Beijing Eye Study served as the external validation set. Different deep learning models were trained, and their CI detection ability was validated. Results: A total of 899 patients in the Chinese Atrial Fibrillation Registry Study were included. In the validation set, the vision-ensemble model based on fundus images alone had an area under the receiver-operating characteristic curve (AUROC) of 0.855 (95% confidence interval 0.816–0.894) for CI screening. The multimodal model (AUROC 0.861, 95% confidence interval 0.823–0.898), based on fundus photographs and 4 clinical variables, performed comparably to the vision-ensemble model. The AUROC of the vision-ensemble model for CI screening achieved 0.773 (95% confidence interval 0.709–0.837) in the external test set. In the saliency map, the vision-ensemble model focused on areas around retinal vessels and the optic disc. Conclusion: A vision-ensemble model based on fundus images might be practical for preliminary screening of CI in AF patients. © 2025 Heart Rhythm Society

关键词： Artificial intelligence Atrial fibrillation Cognitive impairment Deep learning Fundus photography

Compressed Channel Estimation for IRS-Assisted Millimeter Wave OFDM Systems: A Low-Rank Tensor Decomposition-Based Approach

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arXiv 2022年

作者： Zheng, Xi Wang, Peilan Fang, Jun Li, Hongbin The National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu611731 China The Department of Electrical and Computer Engineering Stevens Institute of Technology HobokenNJ07030 United States

We consider the problem of downlink channel estimation for intelligent reflecting surface (IRS)-assisted millimeter Wave (mmWave) orthogonal frequency division multiplexing (OFDM) systems. By exploring the inherent sparse scattering characteristics of mmWave channels, we show that the received signals can be expressed as a low-rank third-order tensor that admits a tensor rank decomposition, also known as canonical polyadic decomposition (CPD). A structured CPD-based method is then developed to estimate the channel parameters. Our analysis reveals that the training overhead required by our proposed method is as low as O(U2), where U denotes the sparsity of the cascade channel. Simulation results are provided to illustrate the efficiency of the proposed method. Copyright © 2022, The Authors. All rights reserved.

关键词： Millimeter waves