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Design and Testing of a Direct Oil Cooled Homopolar Synchronous Generator with Dual DC-Link via Diode Rectifiers

IEEE Transactions on Transportation Electrification 2025年

作者： Vannini, Amedeo Nardo, Mauro Di Rocca, Antonino La Riccio, Jacopo Korman, Oguz Rocca, Salvatore La Marfoli, Alessandro Gerada, Chris University of Nottingham Power Electronics Machines and Control Research Institute NottinghamNG7 2GT United Kingdom Politecnico di Bari Department of Electrical Engineering and Information Technology Bari70126 Italy ARQUIMEA Research Center Santa Cruz de Tenerife Spain

The drivetrains of large transportation systems, such as aircraft or ships, are evolving towards hybrid configurations with DC primary power distribution thanks to their higher efficiency. In this context, synchronous homopolar machines equipped with diode rectifiers are promising solutions for on-board generation units as they eliminate the need for active power electronic converters. In this paper, a synchronous homopolar generator with a dual DC-link configuration, where each power bus is supplied via two series-connected rectifiers, is designed and tested. A direct oil-cooled excitation coil provides the full voltage-control capability of the two independent DC links. The manuscript addresses the challenge of the analytical electromagnetic sizing of this machine topology, which has an intrinsic three-dimensional magnetic behaviour. The electromagnetic design is validated through a 3D-FE analysis, while the thermal sizing of the solenoid hollow oil-cooled excitation coil is analytically carried out and validated through CFD analysis. A 1.2 kW, 6000 rpm proof-of-concept demonstrator has been built and tested, and the reported measurements match the predicted electromagnetic and thermal operation. Although the experimental validation is performed on a small-scale prototype, this work may provide a foundation for designing an active power electronic-free electric generation unit for future large transportation systems. © 2015 IEEE.

关键词： Electromagnetic propulsion

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Enhanced Security Through Honeywords and Video CAPTCHA: An Innovative Authentication and Tracking Mechanism

Enhanced Security Through Honeywords and Video CAPTCHA: An I...

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Advances in Electrical, Computing, Communication and Sustainable Technologies (ICAECT), International Conference on

作者： Madhuri Gurale Komal Borate Rachana R. Sangitrao Garima Tiwari Information Technology Department D. Y. Patil College of Engineering Akurdi Pune India Artifical Intelligency and Data Science Department D. Y. Patil College of Engineering Akurdi Pune India Department of Instrumentation and Control D. Y. Patil College of Engineering Akurdi Pune India Department of Electronics & Communication D. Y. Patil College of Engineering Akurdi Pune India

ISBN: (数字)9798350356236

ISBN: (纸本)9798350356243

In recent years, activities across countries have increasingly been carried out digitally, with information being shared over networks to boost speed and efficiency. However, this digital transformation poses security threats. Cybercrime has consistently evolved, necessitating improved network security measures to combat digital scams. To maintain security, users are assigned unique identification passwords, which they are instructed to keep secret. Despite this, attackers often manage to steal passwords. To counter these threats, we propose using honeywords, which are decoy passwords created from the existing user password. If an attacker inputs a honeyword, an alert is activated for the administrator. Moreover, we implement IP and location monitoring for users and introduce a approach known as the video click-based CAPTCHA system. This scheme authenticates users by distinguishing between humans and bots, addressing issues in traditional graphic password CAPTCHA schemes. This architecture significantly enhances protection and security of data and applications over online networks.

关键词： Resistance Authentication Passwords Network security Reliability Protection Computer crime Usability Monitoring CAPTCHAs

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Photonic axion insulator

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Science (New York, N.Y.) 2025年第6730期387卷 162-166页

作者： Liu, Gui-Geng Mandal, Subhaskar Xi, Xiang Wang, Qiang Devescovi, Chiara Morales-Pérez, Antonio Wang, Ziyao Yang, Linyun Banerjee, Rimi Long, Yang Meng, Yan Zhou, Peiheng Gao, Zhen Chong, Yidong García-Etxarri, Aitzol Vergniory, Maia G. Zhang, Baile Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Research Center for Industries of the Future Department of Electronic and Information Engineering School of Engineering Westlake University Hangzhou China School of Electrical Engineering and Intelligentization Dongguan University of Technology Dongguan China National Laboratory of Solid State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing China Donostia International Physics Center Donostia-San Sebastian Spain Institute for Theoretical Physics ETH Zurich Zurich Switzerland Material and Applied Physics Department University of the Basque Country (UPV/EHU) Donostia-San Sebastián Spain Department of Electronic and Electrical Engineering Southern University of Science and Technology Shenzhen China National Engineering Research Center of Electromagnetic Radiation Control Materials Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China Chengdu China State Key Laboratory of Optical Fiber and Cable Manufacture Technology Department of Electronic and Electrical Engineering Guangdong Key Laboratory of Integrated Optoelectronics Intellisense Southern University of Science and Technology Shenzhen China Centre for Disruptive Photonic Technologies Photonics Institute Nanyang Technological University Singapore IKERBASQUE Basque Foundation for Science Bilbao Spain Max Planck Institute for Chemical Physics of Solids Dresden Germany Département de Physique et Institut Quantique Université de Sherbrooke Sherbrooke Canada

Axions, hypothetical elementary particles that remain undetectable in nature, can arise as quasiparticles in three-dimensional crystals known as axion insulators. Previous implementations of axion insulators have largely been limited to two-dimensional systems, leaving their topological properties in three dimensions unexplored in experiment. Here, we realize an axion insulator in a three-dimensional photonic crystal and probe its topological properties. Demonstrated features include half-quantized Chern numbers on each surface that resembles a fractional Chern insulator, unidirectional chiral hinge states forming topological transport in three dimensions, and arithmetic operations between fractional and integer Chern numbers. Our work experimentally establishes the axion insulator as a three-dimensional topological phase of matter and enables chiral states to form complex, unidirectional three-dimensional networks through braiding.

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Characteristic and Mechanism of Pressure Fluctuation Caused by Self-Induced Oscillation of Supersonic Impinging Jet

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Journal of Thermal Science 2013年第2期22卷 123-127页

作者： Tsuyoshi Yasunobu Yumiko Otobe Hideo Kashimura Department of Control & Information Systems Engineering Kitakyushu College of Technology

When the underexpanded supersonic jet impinges on the obstacle, it is well known that the self-induced flow os- cillation occurs. This oscillation depends on the pressure ratio in the flowfield, the position of an obstacle and is related with the noise problems of aeronautical and other industrial engineering. The characteristic and the mechanism of self-induced flow oscillation, have to be clarified to control various noise problems. But, it seems that the characteristics of the oscillated flowfield and the mechanism of an oscillation have to be more cleared to control the oscillation. This paper aims to clarify the effect of the pressure ratio and the obstacle position and the mechanism of self-induced flow oscillation by numerical analysis and experiment, when the underexpanded su- personic jet impinges on the cylindrical body. From the result of this study, it is clear that occurrence of the self-induced flow osciUation depends on the pressure balance in the flowfield.

关键词： Supersonic Jet Mach Disk Barrel Shock Flow Oscillation Flow Visualization Numerical Analysis

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High-temperature current conduction through three kinds of Schottky diodes

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Chinese Physics B 2009年第11期18卷 5029-5033页

作者：李菲张小玲段毅谢雪松吕长志 Department of Electronic Information and Control Engineering Beijing University of Technology

Fundamentals of the Schottky contacts and the high-temperature current conduction through three kinds of Schottky diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and AlGaN/GaN Schottky diodes are investigated by I-V-T measurements ranging from 300 to 523 K. For these Schottky diodes, a rise in temperature is accompanied with an increase in barrier height and a reduction in ideality factor. Mechanisms are suggested, including thermionic emission, field emission, trap-assisted tunnelling and so on. The most remarkable finding in the present paper is that these three kinds of Schottky diodes are revealed to have different behaviours of high-temperature reverse currents. For the n-Si Schottky diode, a rise in temperature is accompanied by an increase in reverse current. The reverse current of the GaN Schottky diode decreases first and then increases with rising temperature. The AlGaN/GaN Schottky diode has a trend opposite to that of the GaN Schottky diode, and the dominant mechanisms are the effects of the piezoelectric polarization field and variation of two-dimensional electron gas charge density.

关键词： Schottky diodes Schottky barrier height ideality factor reverse current

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Full life-cycle cost model for practical application of solar energy system

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Energy Informatics 2025年第1期8卷

作者： Sha, Ang Xiong, Zhen Zang, Xiaolin Zhao, Wei Ge, Ruibang Yao, Wanxiang Aiello, Marco Innovation Institute for Sustainable Maritime Architecture Research and Technology Qingdao University of Technology Qingdao266033 China School of Architecture and Urban Planning Qingdao University of Technology Qingdao266033 China School of Information and Control Engineering Qingdao University of Technology Qingdao266520 China School of Continuing Education Qingdao University of Technology Qingdao266033 China Service Computing Department Institute of Architecture of Application Systems University of Stuttgart Universitätsstraße 38 Stuttgart70569 Germany

In pursuit of carbon neutrality, a swift transformation is underway in the global energy structure, marked by a consistent rise in the installed capacity of solar energy systems. Meanwhile, the substantial reduction of government subsidies in the solar industry intensifies focus on the economic viability of solar energy installations. In this study, we propose a full life-cycle cost model, named the F-LCC model, for calculating the cost of the solar energy system on the long term, e.g., 20–30 years. This model integrates replacement costs, residual value calculation, interest rate, and inflation impacts while supporting market price estimation for individual components, thereby aiding feasibility analysis in the early project phase. We design an investment cost recovery algorithm based on the F-LCC model to calculate the break-even electricity price for solar energy system. Moreover, we analyze component cost distributions, Net Present Value (NPV), and Discounted Payback Period (DPP) for grid-connected and off-grid solar energy systems with capacities of 10 kWp and 100 kWp in the Chinese market. The results show that the proposed model, compared to other models, captures the fact that payback times are longer. In a solar energy system without storage, solar panels have the highest component cost share at 28.8%. With battery storage, batteries dominate the total cost, reaching up to 74.6%. And the the grid-connected systems DPP ranging from a minimum of 5.5 to a maximum of 7.0 years by grid-connected electricity price, while off-grid systems require at least 19.9 years. The 10 kWp off-grid fixed mounting system’s break-even price being 137.1% higher than its grid-connected counterpart. In addition, tracking-mount systems offer greater cost-reduction potential than fixed installations, with the payback period reduced by 20% for 100 kWp grid-connected systems and 15% for off-grid systems. Finally, we develop a plugin based on the F-LCC model. These findings deepen unde

关键词： Commerce

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Surrogate-Assisted Multiobjective Gene Selection for Cell Classification from Large-Scale Single-Cell RNA Sequencing Data

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IEEE Transactions on Evolutionary Computation 2025年

作者： Lin, Jianqing He, Cheng Jiang, Hanjing Huang, Yabing Jin, Yaochu Huazhong University of Science and Technology Key Laboratory of Image Information Processing and Intelligent Control of Education Ministry of China School of Artificial Intelligence and Automation Wuhan430074 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Wuhan430074 China Renmin Hospital Department of Pathology Wuhan University Wuhan430060 China Westlake University Trustworth and General Artificial Intelligence Laboratory School of Engineering Hangzhou310030 China

Accurate cell classification is crucial but expensive for large-scale single-cell RNA sequencing (scRNA-seq) analysis. Gene selection (GS) emerges as a pivotal technique in identifying gene subsets of scRNA-seq for classification accuracy improvement and gene scale reduction. Nevertheless, the rising scale of scRNA-seq data presents challenges to existing GS methods regarding performance and computational time. Thus, we propose a surrogate-assisted evolutionary algorithm for multiobjective GS to address these deficiencies. An innovative two-phase initialization method is proposed to select sparse solutions to provide preliminary insights into gene contributions. Then, a binary competitive swarm optimizer is proposed for effective global search, where a local search method is embedded to eliminate irrelevant genes for efficiency consideration. Additionally, a surrogate model is adopted to forecast classification accuracy efficiently and substitutes part of the computationally expensive classification process. Experiments are conducted on eight large-scale scRNA-seq datasets with more than 20,000 genes. The effectiveness of the proposed GS method for scRNA-seq cell classification compared with eight state-of-the-art methods is validated. Gene expression analysis results of selected genes further validated the significance of the genes selected by the proposed method in the classification of scRNA-seq data. © 1997-2012 IEEE.

关键词： Gene expression

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Semantic Feature Division Multiple Access for Digital Semantic Multiple Access Channels

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IEEE Transactions on Cognitive Communications and Networking 2025年

作者： Shen, Bin Ma, Shuai Chen, Rui Wu, Youlong Li, Hang Shi, Guangming Li, Shiyin Al-Dhahir, Naofal China University of Mining and Technology School of Information and Control Engineering Xuzhou221116 China Xidian University State Key Laboratory of Integrated Service Networks School of Telecommunications Engineering Shaanxi Xi'an710071 China ShanghaiTech University School of Information Science and Technology Shanghai201210 China Shenzhen Research Institute of Big Data Guangdong Shenzhen518172 China Xidian University School of Artificial Intelligence Shaanxi Xi'an710071 China Peng cheng Laboratory Shenzhen518066 China The University of Texas at Dallas Department of Electrical and Computer Engineering RichardsonTX75080 United States

To solve the multi-user semantic communication network capacity bottlenecks, this paper proposes a semantic feature domain multiple access (SFDMA) scheme. By extracting and encoding semantic features and jointly processing multi-user data, the scheme can realize the encoding and transmission of multi-user semantic information in the separated feature subspace. Based on this scheme, a semantic digital multiple access network model is proposed to perform multi-user inference tasks, and an efficient semantic encoding and decoding scheme is developed by using variational information bottleneck (VIB) theory to ensure both the orthogonality in the feature domain and the classification accuracy. Furthermore, a SFDMA model for image reconstruction is designed based on the Swin Transformer. The modified model also considers the reconstruction quality and orthogonality of semantic feature domain. In addition, we design an optimization target for multiple access to implement an adaptive power allocation method for multi-user semantic communications. Simulation results show that our proposed SFDMA scheme exhibits semantic feature domain orthogonality in different applications, and the adaptive power allocation method shows excellent performance in the classification task, and effectively guarantee the quality of service (QoS) of the semantic communications. © 2015 IEEE.

关键词： Image reconstruction

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Service Function Chain Dynamic Scheduling in Space-Air-Ground Integrated Networks

arXiv

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arXiv 2025年

作者： Jia, Ziye Cao, Yilu He, Lijun Wu, Qihui Zhu, Qiuming Niyato, Dusit Han, Zhu College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing211106 China State Key Laboratory of ISN Xidian University Xian710071 China School of Information and Control Engineering China University of Mining and Technology Xuzhou221116 China School of Computer Science and Engineering Nanyang Technological University Singapore639798 Singapore Department of Electrical and Computer Engineering the University of Houston HoustonTX77004 United States Department of Computer Science and Engineering Kyung Hee University Seoul446-701 Korea Republic of

As an important component of the sixth generation communication technologies, the space-air-ground integrated network (SAGIN) attracts increasing attentions in recent years. However, due to the mobility and heterogeneity of the components such as satellites and unmanned aerial vehicles in multilayer SAGIN, the challenges of inefficient resource allocation and management complexity are aggregated. To this end, the network function virtualization technology is introduced and can be implemented via service function chains (SFCs) deployment. However, urgent unexpected tasks may bring conflicts and resource competition during SFC deployment, and how to schedule the SFCs of multiple tasks in SAGIN is a key issue. In this paper, we address the dynamic and complexity of SAGIN by presenting a reconfigurable time extension graph and further propose the dynamic SFC scheduling model. Then, we formulate the SFC scheduling problem to maximize the number of successful deployed SFCs within limited resources and time horizons. Since the problem is in the form of integer linear programming and intractable to solve, we propose the algorithm by incorporating deep reinforcement learning. Finally, simulation results show that the proposed algorithm has better convergence and performance compared to other benchmark algorithms. Copyright © 2025, The Authors. All rights reserved.

关键词： Network function virtualization

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Resonance-mode-induced beating effect for THz wave generation and principal demonstration

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Optics and Lasers in engineering 2025年 192卷

作者： Tyagi, Deepika Laxmi, Vijay Asrafali, Barkathulla Parveen, Abida Lin, Mi Wang, Qiong Tao, Keyu Liu, Qiang Shen, Suling Ouyang, Zhengbiao THz Technology Laboratory Shenzhen Key Laboratory of Micro-nano Photonic Information Technology Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China College of Mechatronics and Control Engineering Shenzhen University Shenzhen518000 China Department of Biomedical Engineering Southern University of Science and Technology Guangdong Shenzhen518055 China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization College of Civil and Transportation Engineering Shenzhen University Shenzhen518060 China

We present a method of terahertz (THz) wave generation in the complete THz band that harnesses resonance modes within high-quality-factor photonic-crystal resonators. In the proposed method, the input infrared "single-frequency" wave and the resonance mode induced efficiently in the resonator generate a beat note of THz frequency, and the beat note is converted to an independent THz radiation wave with the help of an amplitude demodulator, which provides high power-conversion efficiency (PCE). The theoretical PCE is a 22.93 % half-wave-rectification amplitude demodulator without considering the insertion loss. Through simulations, we demonstrate the feasibility of our approach of inducing a resonance mode from a conventional "single-frequency" wave and using the induced resonance mode to beat with the input source wave with PCE of 24.03 % in agreement with the theoretical PCE value by half-wave-rectification demodulation. Such a high PCE can be obtained only at a certain frequency. The mechanism of the proposed method is further demonstrated experimentally in the microwave band. The proposed method is a general method that can be applied to frequency conversion of all kinds of waves, showcasing its potential across various applications in electronics, optics, acoustics, and beyond. We expect to overcome many future challenges in terahertz technology because of its high efficiency and miniaturization. Furthermore, our findings pave the way for efficient frequency manipulation with broad implications in signal processing, detection, and communication systems. © 2025 Elsevier Ltd

关键词： Terahertz waves

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