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arXiv 2025年

作者： Wan, Liang Mei, Qingsong Liu, Haowen Zhang, Huafeng Du, Jun-Ping Ogata, Shigenobu Geng, Wen Tong School of Physics and Optoelectronic Engineering Yangtze University Jingzhou434023 China Key Laboratory of Micro-Nano Photonic Materials and Devices Yangtze University Jingzhou434023 China School of Power and Mechanical Engineering Wuhan University Wuhan430072 China School of Computer Science Wuhan University Wuhan430072 China Department of Mechanical Science and Bioengineering Osaka University Osaka560-8531 Japan Department of Physics Zhejiang Normal University Jinhua321004 China

Despite its widespread use in materials science, conventional molecular dynamics simulations are severely constrained by timescale limitations. To address this shortcoming, we propose an empirical formulation of accelerated molecular dynamics method, adapted from a collective-variable-based extended system dynamics framework. While this framework is originally developed for efficient free energy sampling and reaction pathway determination of specific rare events in condensed matter, we have modified it to enable accelerated molecular dynamics simulation and prediction of microstructure evolution of materials across a broad range of scenarios. In essence, the nearest neighbor off-centering absolute displacement (NNOAD), which quantifies the deviation of an atom from the geometric center of its nearest neighbors in materials, is introduced. We propose that the collection of NNOADs of all atoms can serve as a generalized reaction coordinate for various structural transitions in materials. The NNOAD of each atom, represented by its three components, is coupled with three additional dynamic variables assigned to the atom. Time evolution of the additional dynamic variables follows Langevin equation, while Nosé-Hoover dynamics is employed to thermostat the system. Through careful analysis and benchmark simulations, we established appropriate parameter ranges for the equations in our method. Application of this method to several test cases demonstrates its effectiveness and consistency in accelerating molecular dynamics simulations and predicting various microstructure evolutions of materials over much longer timescale. We also provide a preliminary theoretical analysis and qualitative justification of the method, offering insights into its underlying principles. Copyright © 2025, The Authors. All rights reserved.

关键词： Microstructural evolution

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Lightning Precursor Discharges and Terrestrial Gamma Ray Flashes

Lightning Precursor Discharges and Terrestrial Gamma Ray Fla...

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US National Committee of URSI National Radio science Meeting (USNC-URSI NRSM)

作者： Victor P. Pasko Sebastien Celestin Anne Bourdon Reza Janalizadeh Zaid Pervez Jaroslav Jansky Pierre Gourbin School of Electrical Engineering and Computer Science Penn State University PA USA Laboratory of Physics and Chemistry of the Environment and Space (LPC2E) CNRS University of Orleans Orleans France Plasma Physics Laboratory (LPP) Ecole Polytechnique Palaiseau France Department of Mathematics and Physics University of Defense Brno Czechia

ISBN: (数字)9781946815200

ISBN: (纸本)9798331513979

Spectacular naturally occurring bursts of X-rays with tens of mega electron-volt energies are observed in association with lightning activity in the Earth's atmosphere. These events were first discovered in 1994 by NASA's Compton Gamma Ray Observatory [Fishman et al., 1994] and are commonly referred to as terrestrial gamma-ray flashes (TGFs). Although since then many other orbital observatories captured these high energy events [Smith et al., 2005; Marisaldi et al., 2010; Briggs et al., 2011; Neubert et al., 2020] and these events have been clearly linked to very intense but short (approximately 10–50 microseconds) bursts of electromagnetic radiation [Ostgaard et al., 2021], the physical nature of these events remains unclear. It is widely recognized that these electromagnetic bursts are also the strongest naturally occurring sources of terrestrial very high frequency (VHF) radiation [Jacobson et al., 2012]. The most puzzling unexplained aspect of these events is that the extreme gamma ray and electromagnetic energy fluxes originate from very compact regions with spatial extent on the order of 100 meters [Lu et al., 2010; Rison et al., 2016; Tilles et al., 2019; Tilles et al., 2020; Kohn et al., 2020; Heumesser et al., 2021], yet they are light-deficient and often even optically undetectable compared to ordinary lightning discharges [Jacobson et al., 2012]. In this work we report on the mechanism that allows precise quantitative explanation of the vast majority of currently accumulated observations of these events at different altitudes in the Earth's atmosphere. The specifics includes TGF fluences and durations, optical darkness, magnitudes and specific waveform characteristics of low and very low frequency radio emissions termed narrow bipolar events and energetic in cloud pulses that are associated with TGFs, the peculiar observations of very fast (typically one tenths of the speed of light) spatial propagation features termed fast positive breakdown in the prese

关键词： Jacobian matrices Observatories Stimulated emission Optical propagation Gamma-rays Lightning X-rays Orbits Discharges (electric) Optical pulses

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Heat transfer software for local materials in Cameroon (HTSLM 1.0): simplified building energy software based on local realities

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Discover Energy 2025年第1期5卷 1-22页

作者： Tchawa, Lynda Phalone Ndjonnou Mandeng, Lucien Mandeng Tchameu, Joël Durel Tchinang Menkem, Ramses Tanankem Kom, Florian Kamsu Ntamag, Jacques Lionel Pondi, Joseph Department of Civil Engineering National Advanced School of Engineering University of Yaoundé I Yaoundé Cameroon Local Materials Promotion Authority (MIPROMALO) Yaoundé Cameroon NASEY OPTICA CHAPTER of the National Advanced School of Engineering of Yaoundé Yaoundé Cameroon Department of Mathematics and Physical Sciences National Advanced School of Engineering of Yaoundé University of Yaoundé I Yaoundé Cameroon Laboratory of Mechanics Materials and Structures Department of Physics Faculty of Science University of Yaoundé I Yaoundé Cameroon MoSIG/DSAI ENSIMAG Grenoble France Department of Computer Science National Advanced School of Engineering of Yaoundé University of Yaoundé I Yaoundé Cameroon LIMOS Université Clermont Auvergne Aubiere France

We report in this work the overall design of a software application for calculating the indoor temperature in a room of a building constructed from local materials in Cameroon based on heat transfer modes. This software is intended to be simplified and at a lower cost for the user. We dubbed it LOBATIN/HTSLM 1.0 for the first release. We describe the physical modeling background based on the stationary aspect of the transfer of heat flow via conduction, convection and radiation from the outside to the inside of the supposedly uninhabited building. We present how we manage Cameroon’s meteorological data to implement them in LOBATIN/HTSLM 1.0 and we compare our results with pre-existing software such as EnergyPlus. The curves obtained for hourly indoor temperatures for the chosen days in the five climatic zones defined for the software, all show a realistic bell-shaped evolution, thus prefiguring a digital decision support tool for such admitted infrastructures to be made of materials from the Local Materials Promotion Authority of Cameroon.

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Leaf Disease Segmentation Using Uunet++ Architecture 3rd

Leaf Disease Segmentation Using Uunet++ Architecture

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3rd International Conference on Trends in Electronics and Health Informatics, TEHI 2023

作者： Farooqui, Nafees Akhter Mishra, Amit Kumar Ray, Kanad Mallik, Saurav Department of Computer Science and Engineering Koneru Lakshmaiah Education Foundation Andhra Pradesh Guntur India Karnataka Bengaluru India Department of Physics Amity School of Applied Sciences Amity University Rajasthan Rajasthan Jaipur India Amity Cognitive Computing and Brain Informatics Centre Amity University Rajasthan Rajasthan303002 India Department of Environmental Health Harvard T H Chan School of Public Health BostonMA02115 United States Pharmacology & Toxicology University of Arizona TucsonAZ85721 United States

ISBN: (纸本)9789819739363

Segmentation of leaves is an initial step in image-based plant phenotyping, which has received more attention recently. Leaf segmentation shows features of the leaf and growth stages at the leaf level. Due to the significant overlapping between leaves and fluctuating environmental circumstances, such as intensity change and blur due to wind, segmentation of plant tissues like leaves is a most important issue in plant phenotyping. The leaf segmentation work has more complicated problems, such as leaf surface, genotypes, length, structure, and thickness variability. This study proposes an ultra-modern deep gaining knowledge of architectures: UUNet++, a convolutional neural network for advance segmentation. A vital assessment is done using computer Vision for Plant Phenotyping dataset (CVPPP). The plant phenotyping is performed on tobacco and Arabidopsis leaf of RGB images from plant village dataset. The proposed model needs less space as compared to the main UNet architecture. In contrast to typical deep learning image sets, this dataset contains a limited number of samples. Despite that, we achieve exceptional results in leaf segmentation, specifically in distinguishing the interior of leaves from the binary segmentation of the entire leaf. Furthermore, studies are necessary to accurately quantify the number of leaves. Without reducing performance measures, the disease classification inferences time is extremely efficient and accurate. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Plant diseases

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Search is All You Need for Few-shot Anomaly Detection

arXiv

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arXiv 2025年

作者： Wang, Qishan Guo, Jia Gao, Shuyong Wang, Haofen Xiong, Li Hu, Junjie Guo, Hanqi Zhang, Wenqiang Academy for Engineering and Technology Fudan University Shanghai China School of Biomedical Engineering Tsinghua University Beijing China School of Computer Science Fudan university Shanghai China College of Design & Innovation Tongji University Shanghai China School of Physics and Mechanical & Electrical Engineering Hexi University Gansu China Engineering Research Center of AI&Robotics Ministry of Education Academy for Engineering&Technology Fudan university Shanghai China

Few-shot anomaly detection (FSAD) has emerged as a crucial yet challenging task in industrial inspection, where normal distribution modeling must be accomplished with only a few normal images. While existing approaches typically employ multi-modal foundation models combining language and vision modalities for prompt-guided anomaly detection, these methods often demand sophisticated prompt engineering and extensive manual tuning. In this paper, we demonstrate that a straightforward nearest-neighbor search framework can surpass state-of-the-art performance in both single-class and multi-class FSAD scenarios. Our proposed method, VisionAD, consists of four simple yet essential components: (1) scalable vision foundation models that extract universal and discriminative features;(2) dual augmentation strategies - support augmentation to enhance feature matching adaptability and query augmentation to address the oversights of single-view prediction;(3) multi-layer feature integration that captures both low-frequency global context and high-frequency local details with minimal computational overhead;and (4) a class-aware visual memory bank enabling efficient one-for-all multi-class detection. Extensive evaluations across MVTec-AD, VisA, and Real-IAD benchmarks demonstrate VisionAD’s exceptional performance. Using only 1 normal images as support, our method achieves remarkable image-level AUROC scores of 97.4%, 94.8%, and 70.8% respectively, outperforming current state-of-the-art approaches by significant margins (+1.6%, +3.2%, and +1.4%). The training-free nature and superior few-shot capabilities of VisionAD make it particularly appealing for real-world applications where samples are scarce or expensive to obtain. Code is available at ***/Qiqigeww/VisionAD. Copyright © 2025, The Authors. All rights reserved.

关键词： Normal distribution

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Blending Optimal Control and Biologically Plausible Learning for Noise-Robust Physical Neural Networks

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Physical Review Letters 2025年第1期134卷 017301-017301页

作者： Satoshi Sunada Tomoaki Niiyama Kazutaka Kanno Rin Nogami André Röhm Takato Awano Atsushi Uchida Faculty of Mechanical Engineering Institute of Science and Engineering Kanazawa University Kakuma-machi Kanazawa Ishikawa 920-1192 Japan Department of Information and Computer Sciences Saitama University 255 Shimo-Okubo Sakura-ku Saitama City Saitama 338-8570 Japan Department of Information Physics and Computing Graduate School of Information Science and Technology The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan

The rapidly increasing computational demands for artificial intelligence (AI) have spurred the exploration of computing principles beyond conventional digital computers. Physical neural networks (PNNs) offer efficient neuromorphic information processing by harnessing the innate computational power of physical processes; however, training their weight parameters is computationally expensive. We propose a training approach for substantially reducing this training cost. Our training approach merges an optimal control method for continuous-time dynamical systems with a biologically plausible training method—direct feedback alignment. In addition to the reduction of training time, this approach achieves robust processing even under measurement errors and noise without requiring detailed system information. The effectiveness was numerically and experimentally verified in an optoelectronic delay system. Our approach significantly extends the range of physical systems practically usable as PNNs.

关键词： Continuous time systems

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Complex Network Modelling with Power-law Activating Patterns and Its Evolutionary Dynamics

arXiv

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arXiv 2025年

作者： Zeng, Ziyan Feng, Minyu Liu, Pengfei Kurths, Jurgen College of Artificial Intelligence Southwest University Chongqing400715 China School of Computer Science and Engineering University of Electronic Science and Technology China University of Electronic Science and Technology China Potsdam Institute for Climate Impact Research Potsdam14437 Germany Institute of Physics Humboldt University of Berlin Berlin Germany

Complex network theory provides a unifying framework for the study of structured dynamic systems. The current literature emphasizes a widely reported phenomenon of intermittent interaction among network vertices. In this paper, we introduce a complex network model that considers the stochastic switching of individuals between activated and quiescent states at power-law rates and the corresponding evolutionary dynamics. By using the Markov chain and renewal theory, we discover a homogeneous stationary distribution of activated sizes in the network with power-law activating patterns and infer some statistical characteristics. To better understand the effect of power-law activating patterns, we study the two-person-two-strategy evolutionary game dynamics, demonstrate the absorbability of strategies, and obtain the critical cooperation conditions for prisoner’s dilemmas in homogeneous networks without mutation. The evolutionary dynamics in real networks are also discussed. Our results provide a new perspective to analyze and understand social physics in time-evolving network systems. Copyright © 2025, The Authors. All rights reserved.

关键词： Markov chains

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A Radio-Frequency Emitter Design for the Low-Frequency Regime in Atomic Experiments

arXiv

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arXiv 2025年

作者： Wei, Yudong Hu, Zhongshu Guo, Yajing Qian, Zhentian Jin, Shengjie Chen, Xuzong Liu, Xiong-Jun International Center for Quantum Materials School of Physics Peking University Beijing100871 China Hefei National Laboratory Hefei230088 China School of Electronics Engineering and Computer Science Peking University Beijing100871 China International Quantum Academy Shenzhen518048 China

Radio frequency (RF) control is a key technique in cold atom experiments. Here, we present a new design based on virtual load, where a low-frequency coil with a frequency of up to 30 MHz, functions as both an inductor and a power-sharing element in a capacitive transformer circuit. This design enables a highly efficient RF circuit with tunable matching bandwidth. It integrates broadband and narrowband coils into a compact configuration, overcoming the distance limitations of metallic chambers. The broadband RF system, tested in a 10-second evaporative cooling experiment, reduced input power from 14.7 dBW to -3.5 dBW due to its low-pass behavior, effectively cooling the Bose-Fermi mixture to below 10 μK. The narrowband RF system was tested in a Landau-Zener experiment and transferred 80 % of Rb atoms from |F = 2,mF = 2〉 to |2,−2〉 in 1 second, yielding a Rabi frequency of 7.6 kHz at 0.1 dBW. The power-sharing properties of the virtual load ensure impedance closely matches the ideal lumped-element simulations, demonstrating the design’s robustness to disturbances. Copyright © 2025, The Authors. All rights reserved.

关键词： Evaporative cooling systems

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Joint Covert and Secure Communication for SWIPT Assisted CNOMA Systems

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IEEE Internet of Things Journal 2025年

作者： Huang, Gaojian Lei, Yuxin Li, Xingwang Khan, Wali Ullah Wang, Gongpu Nallanathan, Arumugam Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo454003 China City University of Macau Faculty of Data Science 999078 China Henan Polytechnic University School of Surveying and Land Information Engineering Jiaozuo454003 China Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo454099 China Southeast University National Mobile Communications Research Laboratory Nanjing210096 China Luxembourg City1855 Luxembourg Beijing Jiaotong University Beijing Key Laboratory of Transportation Data Analysis and Mining School of Computer and Information Technology Beijing100044 China Institute of Internet of Things Wuxi214111 China Queen Mary University of London School of Electronic Engineering and Computer Science LondonE1 4NS United Kingdom Kyung Hee University Department of Electronic Engineering Gyeonggi-do Yongin-si17104 Korea Republic of

With the rapid advancement of physical-layer security technology, the covert and secure communication has become crucial in safeguarding wireless communication systems. In this paper, we propose a joint covert and secure transmission scheme for simultaneous wireless information and power transfer (SWIPT) assisted cooperative non-orthogonal multiple access (CNOMA) systems. In the CNOMA system, a greedy relay transmits the confidential information to the far user (Carol), with the assistance of the near user (Bob). Meanwhile, as a SWIPT node, Bob is self-sustained by harvesting energy from relay. What's more, a warden (Alice) and non-colluding eavesdroppers (Eves) always attempt to detect and capture the confidential information, respectively. To counteract the attacks from Alice and Eves, a jamming-assisted scheme is employed. For the proposed system model, we derive closed-form expressions for the detection error probability (DEP) and the average minimum detection error probability (AMDEP) of Alice. Additionally, closed-form expressions for the outage probability (OP) of users and the intercept probability (IP) of Eves are obtained. Furthermore, to maximize the effective covert rate (ECR) of Carol, an optimization problem is formulated, subject to covertness and security constraints. Numerical results are provided to demonstrate the impact of the system parameters on covert and secure performance, with the results showing perfect agreement with the theoretical analysis. © 2014 IEEE.

关键词： Inductive power transmission

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Hybrid Josephson Rhombus: A Superconducting Element with Tailored Current-Phase Relation

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Physical Review X 2025年第1期15卷 011021-011021页

作者： L. Banszerus C. W. Andersson W. Marshall T. Lindemann M. J. Manfra C. M. Marcus S. Vaitiekėnas Center for Quantum Devices Niels Bohr Institute University of Copenhagen 2100 Copenhagen Denmark Department of Physics University of Washington Seattle Washington 98195 USA Department of Physics and Astronomy Purdue University West Lafayette Indiana 47907 USA Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907 USA School of Electrical and Computer Engineering Purdue University West Lafayette Indiana 47907 USA School of Materials Engineering Purdue University West Lafayette Indiana 47907 USA Materials Science and Engineering University of Washington Seattle Washington 98195 USA

Controlling the current-phase relation (CPR) of Josephson elements is essential for tailoring the eigenstates of superconducting qubits, tuning the properties of parametric amplifiers, and designing nonreciprocal superconducting devices. Here, we introduce the hybrid Josephson rhombus, a highly tunable superconducting circuit containing four semiconductor-superconductor hybrid Josephson junctions embedded in a loop. Combining magnetic frustration with gate-voltage-controlled tuning of individual Josephson couplings provides deterministic control of the harmonic content of the rhombus CPR. We show that, for balanced Josephson couplings at full frustration, the hybrid rhombus displays a π-periodic cos(2φ) potential, indicating coherent charge-4e transport. Tuning away from the balanced configuration, we observe a superconducting diode effect with efficiency exceeding 25%. These results showcase the potential of hybrid Josephson rhombi as fundamental building blocks for noise-resilient qubits and quantum devices with custom transport properties.

关键词： Parametric amplifiers

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