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Design of high-efficiency and large-angle homo-metagratings for light source integration

Optics Express 2023年第15期31卷 24404-24411页

作者： Tsai, Wei-Cheng Hong, Yu-Heng Kuo, Hao-Chung Huang, Yao-Wei Department of Photonics College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Semiconductor Research Center Hon Hai Research Institute Taipei11492 Taiwan

Meta-optics integrated with light sources has gained significant attention. However, most focused on the efficiency of metasurfaces themselves, rather than the efficiency of integration. To design highly efficient beam deflection, we develop a scheme of homo-metagrating, involving the same material for meta-atoms, substrate, and top layer of the laser, to achieve near-unity power from light-emitting to metasurfaces. We utilize three degrees of freedom: overall add-on phase, parameters of meta-atoms in a period, and lattice arrangement. The overall efficiency of homo-metagratings is higher than that of hetero-metagratings. We believe our approach is capable of being implemented in various ultracompact optic systems. © 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Efficiency

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Learning Compositional, Time-Varying Neural Barrier Contracts 27

Learning Compositional, Time-Varying Neural Barrier Contract...

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27th European Conference on Artificial Intelligence, ECAI 2024

作者： Low, Matthew Wang, Timothy E. Nuzzo, Pierluigi Department of Electrical and Computer Engineering University of Southern California Los AngelesCA United States RTX Technology Research Center BerkeleyCA United States Department of Electrical Engineering and Computer Sciences University of California BerkeleyCA United States

ISBN: (纸本)9781643685489

Certificate functions can be used to efficiently capture and prove various properties of a system or controller. Control barrier functions (CBFs) are certificate functions that define a region of forward-invariance, which makes them a natural choice to enforce a notion of "safety" for a system. However, synthesizing CBFs, especially in the case of complex systems with learning-enabled components, remains a challenge. Recent work achieves promising results by leveraging neural networks as function approximators to learn CBFs. However, a single CBF may not exist or be difficult to obtain for complex hybrid systems. To overcome this difficulty, this paper presents a framework to simultaneously learn simpler, time-varying control barrier functions (TV-CBFs) that are composable. We embed these neural certificates in a compositional framework based on assume-guarantee contracts. The resulting neural barrier contracts can then be combined by leveraging the rigorous contract algebra. Learning multiple, composable CBFs empowers the verification process (1) by simplifying the verification of complex systems via decomposition and (2) by broadening the expressivity in capturing complex systems and controllers. We illustrate the effectiveness of our approach on the verification of an aircraft's automatic landing system and a quadrotor navigating an indoor environment. © 2024 The Authors.

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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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Giant phonon-skyrmion coupling in ferromagnet/heavy metal heterostructures

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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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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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Skull Fracture Visualization Using Disk Harmonic Maps 22

Skull Fracture Visualization Using Disk Harmonic Maps

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22nd IEEE International Symposium on Biomedical Imaging, ISBI 2025

作者： Hadjittoouli, Nicolas Pitris, Costas University of Cyprus Kios Research and Innovation Center of Excellence Department of Electrical and Computer Engineering Nicosia Cyprus

ISBN: (纸本)9798331520526

Skull fractures, especially those of the base and facial regions, are challenging to identify due to the intricate anatomy and their subtle morphological characteristics. They necessitate meticulous attention and allocation of sufficient time to ensure accurate diagnosis and optimal patient care. This paper introduces a novel approach that converts a head CT to a mesh representation, in order to utilize disk harmonic mapping and eventually create a flatten map of the skull for improved visualization. In such a view, fractures appear continuous with enhanced contrast. The effectiveness of this technique was evaluated using the CQ500 dataset. This alternative visualization of a flattened skull can provide radiologists and emergency department personnel a valuable addition to conventional radiological views, increasing the effectiveness and speed of skull fracture detection. © 2025 IEEE.

关键词： Computed Tomography computer-Aided Diagnosis image processing medical imaging skull fracture

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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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