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Giant phonon-skyrmion coupling in ferromagnet/heavy metal heterostructures

Physical Review B 2024年第6期110卷 064423-064423页

作者： Egor Savostin Vitaliy Lomakin Program in Materials Science and Engineering Center for Memory and Recording Research Department of Electrical and Computer Engineering

The strong impact of the strain-induced Dzyaloshinskii-Moriya interaction (SIDMI) on the magnetization dynamics of skyrmions in nanomagnetic structures is demonstrated. The effects of SIDMI are characterized by skyrmion equations (SEs) of motion and magnetoelastic (ME) equations. The study is performed on a model system of MgO/CoFe/Pt stacked on a piezoelectric substrate. The results demonstrate a major nonlinear amplification in both the first- and higher-harmonic magnitudes of the skyrmion breathing mode due to SIDMI. Remarkably, this enhancement can trigger a skyrmion collapse, enabling its deletion with ultraweak strain-induced excitations. The SIDMI effect is shown to be much more significant than the conventional ME effect. These findings open different avenues for the efficient manipulation of nanomagnetic structures through strain.

关键词： Exchange interaction Magnetic interactions Magnetization dynamics Magnetoacoustic effect Micromagnetism Spin dynamics

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A Link-Quality Anomaly Detection Framework for Software-Defined Wireless Mesh Networks

IEEE Transactions on Machine Learning in Communications and ...

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IEEE Transactions on Machine Learning in Communications and Networking 2024年 2卷 495-510页

作者： Skaperas, Sotiris Mamatas, Lefteris Tsaoussidis, Vassilis University of Macedonia Department of Applied Informatics Thessaloniki546 36 Greece Athena Research and Innovation Center Marousi15125 Greece Democritus University of Thrace Department of Electrical and Computer Engineering Xanthi67100 Greece

Software-defined wireless mesh networks are being increasingly deployed in diverse settings, such as smart cities and public Wi-Fi access infrastructures. The signal propagation and interference issues that typically characterize these environments can be handled by employing SDN controller mechanisms, effectively monitoring link quality and triggering appropriate mitigation strategies, such as adjusting link and/or routing protocols. In this paper, we propose an unsupervised machine learning (ML) online framework for link quality detection consisting of: 1) improved preprocessing clustering algorithm, based on elastic similarity measures, to efficiently characterize wireless links in terms of reliability, and 2) a novel change point (CP) detector for the real-time identification of anomalies in the quality of selected links, which minimizes the overestimation error through the incorporation of a rank-based test and a recursive max-type procedure. In this sense, considering the communication constraints of such environments, our approach minimizes the detection overhead and the inaccurate decisions caused by overestimation. The proposed detector is validated, both on its individual components and as an overall mechanism, against synthetic but also real data traces;the latter being extracted from real wireless mesh network deployments. © 2023 CCBY.

关键词： Real time systems

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Energy-Efficient Fast Object Detection on Edge Devices for IoT Systems

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IEEE Internet of Things Journal 2025年第11期12卷 16681-16694页

作者： Nurul Achmadiah, Mas Ahamad, Afaroj Sun, Chi-Chia Kuo, Wen-Kai National Formosa University SMIM Research Center Department of Electro-Optics Huwei632 Taiwan Yuan Ze University Department of Computer Science and Engineering Taoyuan320 Taiwan National Taipei University Department of Electrical Engineering Taipei237303 Taiwan National Formosa University Department of Electro-Optics Huwei632 Taiwan

This article presents an Internet of Things (IoT) application that utilizes an AI classifier for fast-object detection using the frame difference method. This method, with its shorter duration, is the most efficient and suitable for fast-object detection in IoT systems, which require energy-efficient applications compared to end-to-end methods. We have implemented this technique on three edge devices: 1) AMD AlveoTMU50;2) Jetson Orin Nano;and 3) Hailo- 8TM AI Accelerator, and four models with artificial neural networks and transformer models. We examined various classes, including birds, cars, trains, and airplanes. Using the frame difference method, the MobileNet model consistently has high accuracy, low latency, and is highly energy-efficient. YOLOX consistently shows the lowest accuracy, lowest latency, and lowest efficiency. The experimental results show that the proposed algorithm has improved the average accuracy gain by 28.314%, the average efficiency gain by 3.6 times, and the average latency reduction by 39.305% compared to the end-to-end method. Of all these classes, the faster objects are trains and airplanes. Experiments show that the accuracy percentage for trains and airplanes is lower than other categories. So, in tasks that require fast detection and accurate results, end-to-end methods can be a disaster because they cannot handle fast object detection. To improve computational efficiency, we designed our proposed method as a lightweight detection algorithm. It is well suited for applications in IoT systems, especially those that require fast-moving object detection and higher accuracy. © 2014 IEEE.

关键词： Neural networks

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Coupling Mobile Brain Imaging and Virtual Reality Omnidirectional Treadmill to Explore Attenuated Situational Awareness during Distracted Walking

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IEEE Transactions on Cognitive and Developmental Systems 2024年第3期16卷 1063-1076页

作者： Chuang, Chun-Hsiang Chiu, Tsai-Feng Hsu, Hao-Che Lin, Shih-Syun National Tsing Hua University Research Center for Education and Mind Sciences College of Education The Institute of Information Systems and Applications College of Electrical Engineering and Computer Science Hsinchu300 Taiwan National Tsing Hua University Research Center for Education and Mind Sciences Hsinchu300 Taiwan National Yang Ming Chiao Tung University Department of Computer Science Hsinchu300193 Taiwan National Taiwan Ocean University Department of Computer Science and Engineering Keelung20224 Taiwan

Walking while engaging in distracting activities affects our perception of changes happening on the road, leading to exposure to hazardous conditions. This study aimed to evidence that pedestrians who become distracted when absorbed in their smartphones fail to maintain situational awareness. Thirty-six recruited participants performed a psychomotor vigilance task and a wayfinding task designed to simulate a multitasking scenario;meanwhile, an auditory oddball paradigm presented to participants tested their situational awareness of an external stimulus. The experiment was conducted in virtual reality (VR) environment with an omnidirectional treadmill. Participant's behavioral and electroencephalographic (EEG) responses were measured and analyzed using a newly proposed brain network measure, phase locking distance (PLD), to capture multitasking-associated couplings between brain regions. The current study supports the notion that multitasking can lead to diminished behavioral performance and changes in walking patterns. Despite the increased interregional brain connectivity, which may be an adaptive response to heightened cognitive demands, the associated reduction in event-related EEG activity suggests competition for neural resources during multitasking. Moreover, the observed EEG activities could indicate additional information processing capacity limitations and provide evidence of decreased situational awareness during multitasking, thereby increasing susceptibility to potentially hazardous situations. © 2016 IEEE.

关键词： Electroencephalography

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RP-SWSGD: Design of sliding window stochastic gradient descent method with user’s ratings pattern for recommender systems

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Multimedia Tools and Applications 2024年第14期83卷 41083-41120页

作者： Khan, Zeshan Aslam Raja, Hafiz Anis Chaudhary, Naveed Ishtiaq Iqbal, Sumbal Mehmood, Khizer Raja, Muhammad Asif Zahoor Department of Electrical and Computer Engineering International Islamic University Islamabad Pakistan Future Technology Research Center National Yunlin University of Science and Technology 123 University Road Section 3 Yunlin Douliou64002 Taiwan

To offer relevant and useful recommendations, the crucial role of recommender systems in e-commerce industry is to predict the users’ concern for various items by estimating items’ attributes and users’ preferences. The reliability of a recommender system is usually assessed through accuracy and speed of relevant recommendations for a variety of items. The matrix factorization-based stochastic gradient descent (SGD) methods proposed by researchers lack memory needed to capture the ratings history hidden in the previous iterations. Recently, sliding window-based SGD strategies designed for Recommender systems and Hammerstein nonlinear systems gained attention due to the improved performance in terms of convergence speed and estimated accuracy. The memory impact with regard to the historical information enhances the performance of sliding window-based SGD techniques. However, sliding window-based methods are deficient in capturing the ratings history based on the users’ rating patterns. Hence utilizing the same window length for the set of observed ratings rated by users. Therefore, we propose an improved sliding window-based SGD strategy to acquire historical information of the ratings with respect to a user’s rating patterns for efficient matrix factorization of recommender systems. The proposed strategy performs significantly by accomplishing fast convergence speed and accuracy for window sizes greater than 1. The accuracy of the suggested technique is verified for two benchmark datasets such as ML-100 K and Film-Trust. However, the authenticity of the proposed method as compared to the standard counterpart (window size = 1) is confirmed through Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE). The average improvements achieved by the proposed strategy in terms of RMSE and MAE over the baseline for ML-100 K dataset are 0.726% and 2.245% respectively. Whereas the proposed method accomplishes considerable average improvement of 7.89% and 9.41% for RMSE an

关键词： Recommender systems

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AN AC-DC COUPLED IMPEDANCE MODEL AND STABILITY ANALYSIS FOR MORE ELECTRIC AIRCRAFT

AN AC-DC COUPLED IMPEDANCE MODEL AND STABILITY ANALYSIS FOR ...

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2024 CSAA/IET International Conference on Aircraft Utility Systems, AUS 2024

作者： Zhang, Tieyan Gao, Fei Gu, Chunyang Zhang, Boshen Chen, Jiawei Chen, Jie Department of Electrical Engineering Shanghai Jiao Tong University Shanghai China Advanced Electrical Machine Drive Research Center Yongjiang Laboratory Ningbo China College of Automation Chongqing University Chongqing China College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing China

High voltage DC systems have become one of the dominant electrical power system architectures for future applications in more electric aircraft. Accurate model and stability analysis of these systems are crucial. However, past studies typically use the DC impedance model, which may overlook some system characteristics. Additionally, the impedance model needs repetitive adjustment as the source side and the load side change. In this paper, an AC-DC coupled impedance model is proposed, which can model the overall system into submodules. The resulting converter impedance is independent of load and source-side parameters, which means that changes on the AC and DC side have no effect on the converter impedance model. Furthermore, this model is more accurate as it includes AC, DC, and AC-DC coupled terms, better aligning with actual onboard characteristics. The modelling process, frequency sweep verification, and stability analysis in MATLAB/Simulink are provided in this paper. © The Institution of engineering & Technology 2024.

关键词： Aircraft power systems

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Far-field super-resolution chemical microscopy

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Light(Science & Applications) 2023年第7期12卷 1246-1267页

作者： Mingwei Tang Yubing Han Danchen Jia Qing Yang Ji-Xin Cheng State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China Intelligent Perception Research Institute Zhejiang LabHangzhou 311100China Department of Biomedical Engineering Department of Electrical and Computer EngineeringPhotonics CenterBoston UniversityBostonMA 02459USA

Far-feld chemical microscopy providing molecular electronic or vibrational fingerprint information opens a new window for the study of three-dimensional biological,material,and chemical *** microscopy provides a nondestructive way of chemical identification without exterior ***,the diffraction limit of optics hindered it from discovering more details under the resolution *** development of super-resolution techniques gives enlightenment to open this door behind far-field chemical ***,we review recent advances that have pushed the boundary of far-field chemical microscopy in terms of spatial *** further highlight applications in biomedical research,material characterization,environmental study,cultural heritage conservation,and integrated chip inspection.

关键词： chemical details optics

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Finite-Time Distributed Identification for Nonlinear Interconnected Systems

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IEEE/CAA Journal of Automatica Sinica 2022年第7期9卷 1188-1199页

作者： Farzaneh Tatari Hamidreza Modares Christos Panayiotou Marios Polycarpou Mechanical Engineering Department Michigan State UniversityEast LansingMI 48824 USA KIOS Research and Innovation Center of Excellence and the Department of Electrical and Computer Engineering University of CyprusNicosia 1678Cyprus IEEE

In this paper,a novel finite-time distributed identification method is introduced for nonlinear interconnected systems.A distributed concurrent learning-based discontinuous gradient descent update law is presented to learn uncertain interconnected subsystems’*** concurrent learning approach continually minimizes the identification error for a batch of previously recorded data collected from each subsystem as well as its neighboring *** state information of neighboring interconnected subsystems is acquired through direct *** overall update laws for all subsystems form coupled continuous-time gradient flow dynamics for which finite-time Lyapunov stability analysis is *** a byproduct of this Lyapunov analysis,easy-to-check rank conditions on data stored in the distributed memories of subsystems are obtained,under which finite-time stability of the distributed identifier is *** rank conditions replace the restrictive persistence of excitation(PE)conditions which are hard and even impossible to achieve and verify for interconnected ***,simulation results verify the effectiveness of the presented distributed method in comparison with the other methods.

关键词： Distributed concurrent learning finite-time identification nonlinear interconnected systems unknown dynamics

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Design and Implementation of Optimized Resource Low-Power SoC Multi-Soft-Processor FPGA Hardware Acceleration Architecture for Fast Digital Image Processing

Design and Implementation of Optimized Resource Low-Power So...

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2023 IEEE National Aerospace and Electronics Conference, NAECON 2023

作者： Namou, L. Megherbi, D.B. University of Massachusetts Cminds Research Center Department of Electrical and Computer Engineering LowellMA01854 United States

ISBN: (纸本)9798350338782

This paper focuses on designing, implementing, and optimizing a distributed multi-soft-processor SoC low-power FPGA-based software-hardware co-design architecture for fast digital image processing computing acceleration. The paper demonstrates an on and off-the-chip augmented hardware architecture implementation to overcome Memory, Cost, Size, and Power prohibitive resource constraints. This implementation experimentally achieves an optimized accelerated digital image processing and digital filtering execution time. The method achieves 80 times computational speedup with the proposed augmented hardware-accelerated optimization scheme compared to an initial practical implementation without hardware acceleration. This design is implemented on an SoC Altera Cyclone- V FPGA. In this design, an FPGA Multi Softcore Processor is instantiated in the fabric and interfaced with an external SDRAM via a 16-bit Memory Controller Intellectual Property (IP) core. An 8-bit intensity resolution image (up to 1280 x 1280 pixels, but not limited) was imported from a PC (via Serial Communication) to the FPGA for Sobel spatial filter processing. Each Soft Core was memory mapped to each image segment to create a parallel multiprocessing architecture. Multiple Sobel Filters are written and synthesized in the fabric. The Register Transfer Logic (RTL) code is written in VHDL and Verilog as a Hardware Description Language (HDL) to accelerate the design implementation. A different number of Softcore Processors in conjuncture with accelerated hardware are tested to compare the resulting computational efficiency. The timings between accessing the on-chip SRAM and the off-chip SDRAM can also be compared. In the final analysis, understanding that the FPGA Softcore using C is quick to implement and flexible to interface with, but it is a non-deterministic and sequentially executed process, and that the FPGA Fabric using HDL is rigid and constraint-driven, but no overhead, implemented in fabric, det

关键词： Field programmable gate arrays (FPGA)

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Resource Allocation for Fairness Enhancement in Multi-Cell Vehicular VLC System With Optical IRS: A Cooperative Transmission Approach

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IEEE Internet of Things Journal 2025年第11期12卷 16931-16946页

作者： An, Nan Yang, Fang Liu, Chang Cheng, Ling Song, Jian Han, Zhu Tsinghua University Beijing National Research Center for Information Science and Technology Department of Electronic Engineering Beijing100084 China Center of National Railway Intelligent Transportation System Engineering and Technology Beijing100081 China China Academy of Railway Sciences Corporation Limited Signal and Communication Research Institute Beijing100081 China University of the Witwatersrand School of Electrical and Information Engineering Johannesburg2050 South Africa Tsinghua University Department of Electronic Engineering Beijing National Research Center for Information Science and Technology Beijing100084 China Tsinghua University Shenzhen International Graduate School Shenzhen518055 China University of Houston Department of Electrical and Computer Engineering HoustonTX77004 United States Kyung Hee University Department of Computer Science and Engineering Seoul446-701 Korea Republic of

In multi-cell downlink vehicular visible light communication (VLC) systems, vehicles at a cell edge experience lower achievable data rates compared with those at a cell center, primarily due to the weaker channel gain and inter-cell interference, leading to unfairness among vehicles. In this paper, a cooperative transmission approach is proposed for a vehicular VLC system with optical intelligent reflecting surface (OIRS) to enhance the max-min fairness of the system by leveraging the additional OIRS-reflected channels and the interference-mitigating capabilities of cooperative transmission. To this end, the system model is established, followed by the formulation of a resource allocation problem aiming at enhancing max-min fairness, in which the minimum achievable data rate among vehicles is optimized. Then, an effective resource algorithm is proposed, transforming the original problem into an equivalent form and subsequently decomposing it into three subproblems, focusing on OIRS assignment, subchannel allocation, and power adjustment, respectively. By employing a block coordinate descent algorithm, the three subproblems are solved iteratively until convergence. In addition, simulation results confirm the improvement in max-min fairness brought by OIRS and the proposed cooperative transmission approach. Moreover, compared with various baselines, the proposed resource allocation algorithm significantly enhances in the max-min fairness for the vehicular VLC system, crucial for this application. © 2014 IEEE.

关键词： Resource allocation

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