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A wideband circularly polarized crossed dipole antenna with compact structure and frequency reconfiguration

MICROWAVE AND OPTICAL technology LETTERS 2021年第7期63卷 1886-1891页

作者： Li, Wentao Qu, Haotian Wang, Yiming Wei, Meng Hei, Yongqiang Xidian Univ Sch Elect Engn Xian 710071 Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian Peoples R China

In this letter, a novel wideband circularly polarized (CP) crossed dipole antenna with frequency reconfiguration is proposed. By introducing two quasi-Sierpinski fractal orthogonal dipoles printed on both sides of the substrate, compact, broadband and low cross-polarization characteristics are achieved. The proposed antenna can be switched flexibly over two frequency bands via controlling the states of the PIN diodes inserted in each arm of the crossed dipole. The measured -10 dB impedance bandwidths of the antenna are 63% in 2.23-4.27 GHz and 12.5% in 4.04-4.58 GHz, respectively. Meanwhile, the 3 dB axial ratio bandwidths are 34.7% in 2.5-3.55 GHz and 4.16% in 4.23-4.41 GHz, respectively. The proposed antenna is desired to be applied in the future wireless communication systems.

关键词： circular polarization crossed dipole fractal structure frequency reconfiguration

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High-temperature oxidation resistance of spent MoSi2 modified ZrB2-SiC-MoSi2 coatings prepared by spark plasma sintering

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CERAMICS INTERNATIONAL 2023年第20期49卷 32913-32922页

作者： Mao, Chenhao Ren, Xuanru Ji, Xiang Xu, Leihua Wang, Xiaoye Zhu, Nana Zhang, Ping Feng, Peizhong China Univ Min & Technol Sch Mat & Phys Xuzhou 221116 Jiangsu Peoples R China Henan Acad Sci Carbon Matrix Composites Res Inst Henan Key Lab High Performance Carbon Fiber Reinfo Zhengzhou 450046 Peoples R China

The spent MoSi2 modified ZrB2-SiC-MoSi2 coatings were prepared on carbon matrixes by spark plasma sintering. A continuous metallurgical bonding was formed at the interface between the coating and matrix, and no obvious defects such as pores and cracks were observed inside. The effects of spent MoSi2 content and trace doping in the spent powder on the oxidation behavior of the coatings in air at 1700 degrees C were investigated. During the active oxidation stage, the spent MoSi2 promoted the densification of the coating and enhanced the structural oxygen barrier properties. With the increase of service time, during the inert oxidation stage, doping an appropriate amount of spent MoSi2 helped to increase the fluidity of the rich-SiO2 protective layer so that the Zr oxides fully dispersed in the generated Zr-B-Si-O-Al multiphase glass layer, which could impede the penetration of oxygen and enhance the oxidation protection efficiency. However, excessive spent MoSi2 exacerbated the volatilization of gas by-products, forming pores and cracks in the glass layer and rising the oxidation loss. When the content of spent MoSi2 was 20 vol%, the glass layer is dense and uniform, with few defects and the best oxygen resistance property. Moreover, compared with commercial powders, spent MoSi2 contained Al2O3 and SiO2. Al2O3 had an excellent modification effect, while SiO2 glass can promote liquid phase sintering and seal the defects in the coatings. By adding spent MoSi2, the modified ZrB2-SiC-MoSi2 composite coatings could inhibit the formation of defects and improve the dynamic stability of the coatings effectively.

关键词： SpentMoSi2 ZrB2-SiC-MoSi2 coating Active/inert oxidation Oxygen permeability Multiphase glass layer

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Constructing Cyber-Physical System Testing Suites Using Active Sensor Fuzzing

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IEEE TRANSACTIONS ON SOFTWARE engineering 2023年第11期49卷 4829-4845页

作者： Zhang, Fan Wu, Qianmei Xuan, Bohan Chen, Yuqi Lin, Wei Poskitt, Christopher M. Sun, Jun Chen, Binbin Zhejiang Univ Coll Comp Sci & Technol Hangzhou 310027 Peoples R China ZJU Hangzhou Global Sci & Technol Innovat Ctr Hangzhou 311200 Peoples R China Key Lab Blockchain & Cyberspace Governance Zhejian Hangzhou 310027 Peoples R China Zhejiang Univ Jiaxing Res Inst Jiaxing 314000 Peoples R China Zhengzhou Xinda Inst Adv Technol Zhengzhou 450000 Peoples R China ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Singapore Univ Technol & Design Informat Syst Technol & Design Pillar Singapore 487372 Singapore Singapore Management Univ Sch Comp & Informat Syst Singapore 178902 Singapore

Cyber-physical systems (CPSs) automating critical public infrastructure face a pervasive threat of attack, motivating research into different types of countermeasures. Assessing the effectiveness of these countermeasures is challenging, however, as benchmarks are difficult to construct manually, existing automated testing solutions often make unrealistic assumptions, and blindly fuzzing is ineffective at finding attacks due to the enormous search spaces and resource requirements. In this work, we propose active sensor fuzzing, a fully automated approach for building test suites without requiring any a prior knowledge about a CPS. Our approach employs active learning techniques. Applied to a real-world water treatment system, our approach manages to find attacks that drive the system into 15 different unsafe states involving water flow, pressure, and tank levels, including nine that were not covered by an established attack benchmark. Furthermore, we successfully generate targeted multi-point attacks which have been long suspected to be possible. We reveal that active sensor fuzzing successfully extends the attack benchmarks generated by our previous work, an ML-guided fuzzing tool, with two more kinds of attacks. Finally, we investigate the impact of active learning on models and the reason that the model trained with active learning is able to discover more attacks.

关键词： Fuzzing Benchmark testing Actuators Predictive models Space exploration Data models Process control Cyber-physical systems fuzzing testing machine learning metaheuristic optimisation

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Autonomous Robotic Ultrathin Laser-Scribed Microheater for Effective Insect Control

ADVANCED INTELLIGENT SYSTEMS

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advanced INTELLIGENT SYSTEMS 2025年第2期7卷

作者： Poon, Wing Yan Zhong, Haosong Xu, Yang Kim, Minseong Lin, Jing Yang, Rongliang Lee, Kong Wai Yuan, Qiaoyaxiao Tam, Wan Hin Li, Mitch Guijun Hong Kong Univ Sci & Technol Ctr Smart Mfg Div Integrat Syst & Design Kowloon Clear Water Bay Hong Kong 999077 Peoples R China Hong Kong Univ Sci & Technol State Key Lab Adv Displays & Optoelect Technol Kowloon Clear Water Bay Hong Kong 999077 Peoples R China

Insects such as ants and termites have always been a common household hazard, closely correlated to various health risks causing allergies or infections. Present-day chemical insecticides pose carcinogenic threats to human health and the environment, according to the World Health Organisation. Herein, a novel autonomous robotic ultrathin laser-scribed microheater is presented as a safe, efficient, and cost-effective alternative for insect control. A microheater is fabricated using an array of laser-scribed micro-wires and an autonomous robotic module, allowing for rapid and uniform heat transfer in less than 3 s. The integrated robotic microheater successfully (100%) eradicates household ants at 60 degrees C within 30 s. Such results significantly advance insect control, reducing treatment time from hours to seconds while attenuating chemical insecticides' critical safety and health risks. Ultimately, this innovative approach demonstrates the promise of autonomous robotic microheaters for broader agriculture, healthcare, and manufacturing applications, where insect control is crucial. A novel laser-assisted micro-heating autonomous robot is developed to deliver a safe and effective pest control strategy. The robot has laser-scribed micropores and a microwire array, promoting a rapid and uniform heat distribution. The results show that it successfully exterminated 100% of Tapinoma melanocephalum in 30 s, advancing pest control technologies and reducing reliance on dangerous *** (c) 2024 WILEY-VCH GmbH

关键词： autonomous robots laser-assisted manufacturing micro-heating pest control

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Object-Attribute-Relation Representation Based Video Semantic Communication

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IEEE Journal on Selected Areas in Communications 2025年第7期43卷 2446-2461页

作者： Du, Qiyuan Duan, Yiping Yang, Qianqian Tao, Xiaoming Debbah, Merouane Tsinghua University Department of Electronic Engineering Beijing China Beijing China State Key Laboratory of Space Network and Communications Beijing China Zhejiang University College of Information Science and Electronic Engineering Hangzhou China Xinjiang University School of Computer Science and Technology Xinjiang China Khalifa University KU6G Research Center Department of Computer and Information Engineering Abu Dhabi127788 United Arab Emirates University Paris-Saclay CentraleSupelec Gif-sur-Yvette91192 France

With the rapid growth of multimedia data volume, there is an increasing need for efficient video transmission in applications such as virtual reality and future video streaming services. Semantic communication is emerging as a vital technique for ensuring efficient and reliable transmission in low-bandwidth, high-noise settings. However, most current approaches focus on joint source-channel coding (JSCC) that depends on end-to-end training. These methods often lack an interpretable semantic representation and struggle with adaptability to various downstream tasks. In this paper, we introduce the use of object-attribute-relation (OAR) as a semantic framework for videos to facilitate low bit-rate coding and enhance the JSCC process for more effective video transmission. We utilize OAR sequences for both low bit-rate representation and generative video reconstruction. Additionally, we incorporate OAR into the image JSCC model to prioritize communication resources for areas more critical to downstream tasks. Our experiments on traffic surveillance video datasets assess the effectiveness of our approach in terms of video transmission performance. The empirical findings demonstrate that our OAR-based video coding method not only outperforms H.265 coding at lower bit-rates but also synergizes with JSCC to deliver robust and efficient video transmission. © 1983-2012 IEEE.

关键词： Video streaming

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Correlating multi-scale structure characteristics to mechanical behavior of Caprinae horn sheaths

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JOURNAL OF MATERIALS RESEARCH AND technology-JMR&T 2022年 21卷 2191-2202页

作者： Yang, Kang Qin, Nannan Zhou, Changgeng Deng, Hailiang Tian, Wenhan Cai, Siyu Wu, Zihong Guan, Juan Anhui Univ Technol Key Lab Green Fabricat & Surface Technol Adv Met M Minist Educ Maanshan 243002 Peoples R China Anhui Univ Technol Sch Mat Sci & Engn Maanshan 243002 Peoples R China Fudan Univ State Key Lab Mol Engn Polymers Shanghai 200433 Peoples R China Corporation Ltd Aviat Ind Corp China AVIC Composite Composite Component Technol Ctr Beijing 101300 Peoples R China Beihang Univ Int Res Ctr Adv Struct & Biomat Sch Mat Sci & Engn Beijing 100191 Peoples R China Guiyang Engine Res Inst Aviat Ind Corp China AV Guiyang 550081 Peoples R China

Horns are used by Bovidae animals for intraspecific combat;as such they are among Na-ture's toughest materials that require resistance to extreme loads. As a typical subfamily among Bovidae, Caprinae own light-wight horn with balanced strength and toughness. However, their structure and the salient mechanisms that underlie their mechanical behavior remain uncertain. This work clarifies the effect of multi-scale structure charac-teristics on mechanical behaviors of horn sheath by comparing Cashmere goat, White goat and Black sheep. With the methods of fractographic observations, conformational analysis, acoustic emission and finite element methods. Conformation of keratin and strength of fibre were proposed to influence the tensile/flexural performance a lot under both dried and hydrated condition. The corrugated lamellae structure was assumed to promote crack deflection and enhance dried samples, which showed more advantageous for applications of flexural loading. It is hard to impute the difference of mechanics to any one factor, and the synergism of multi-scale mechanisms is important to mechanical properties in Cap-rinae horn sheath. This research is expected to further encourage the horn-inspired design of secondary load-carrying lightweight composites.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Caprinae horn sheaths Multi -scale structure Mechanical behavior Corrugated lamellae

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Research on the parameter calibration and the interaction mechanisms of irregular wet particles

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POWDER technology 2025年 457卷

作者： Zhou, Jiacheng Liu, Fei Zhang, Libin Chen, Liuyang Wang, Xuesong Duan, Chenlong Jiang, Haishen Pan, Miao Wuhan Text Univ Sch Mech Engn & Automat Hubei Key Lab Digital Text Equipment Wuhan 430200 Peoples R China Zhejiang Univ State Key Lab Silicon & Adv Semicond Mat Hangzhou 310027 Peoples R China China Univ Min & Technol Sch Chem Engn & Technol Xuzhou Peoples R China Taiyuan Heavy Machinery Grp Co Ltd Taiyuan Peoples R China

To increase the accuracy of simulation parameters for wet irregular particles and investigate the interaction mechanisms between wet particles, the parameters for three types of irregular wet particles are calibrated and validated. Firstly, the models for the three types of wet irregular particles are constructed, and the corresponding stacking angles are obtained. Then, the linear regression equation between the significant parameters and the particle stacking angle is established to validate the relative errors. The results showed that the relative errors for the simulated and experimental stacking angles of the capsule, cassia seed, and colored sand particles are 1.83 %, 1.51 %, and 2.23 %, respectively. These relative errors are lower than those reported in existing literature. Moreover, particle fluidity tests are conducted to explore the particle interaction mechanisms. The results indicate that the smooth and hydrophilic particle surfaces are more likely to accumulate water molecules and form liquid bridges, which lead to enhanced adhesion and decreased particle fluidity. On the contrary, the liquid bridge is more prone to fracture on a rough and hydrophobic particle surface, which leads to decreased adhesion and enhanced particle fluidity. The study demonstrates that this parameter calibration method and the interaction mechanisms of wet irregular particles are reliable.

关键词： Irregular wet particles DEM modeling Stacking angle Parameter calibration JKR model Interaction mechanisms

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Control of Variable Speed Pumped Storage Unit Based on Power Electronic Transformer Under Unbalance of Power Grid Voltage

Control of Variable Speed Pumped Storage Unit Based on Power...

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International Conference on Electrical Machines and Systems (ICEMS)

作者： Pei Huang Xiang Peng Renjun Dian School of Information Science and Engineering Wuhan University of Science and Technology Wuhan China Engineering Research Center for Metallurgical Automation and Measurement Technology of Ministry of Education Wuhan University of Science and Technology Wuhan China

ISBN: (数字)9784886864406

ISBN: (纸本)9798350379105

To enhance the power density and improve the grid-connection capability of the variable-speed pumped storage unit, this paper proposes a topology for full-power variable-speed pumped storage based on power electronic transformer. This topology does not require a power frequency transformer and can isolate the double frequency fluctuation of the high-voltage DC bus voltage in the event of asymmetric faults in the grid, so as not to affect the control of the motor side and improve the unit's ability to adapt to the power grid.

关键词： Fluctuations Pumps High-voltage techniques Transformers Motors Power grids Power electronics Topology Voltage control Frequency control

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Verifiable and Dynamic Multi-keyword Search Over Encrypted Cloud Data Using Bitmap

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IEEE TRANSACTIONS ON CLOUD COMPUTING 2023年第1期11卷 336-348页

作者： Li, Feng Ma, Jianfeng Miao, Yinbin Jiang, Qi Liu, Ximeng Choo, Kim-Kwang Raymond Xidian Univ Sch Cyber Engn Xian 710071 Shaanxi Peoples R China Guilin Univ Elect Technol Guangxi Key Lab Trusted Software Guilin 541004 Peoples R China City Univ Hong Kong Dept Comp Sci Hong Kong 999077 Peoples R China Xidian Univ Sch Cyber Engn Shaanxi Key Lab Network & Syst Secur Xian 710071 Shaanxi Peoples R China Network Commun Res Ctr Peng Cheng Lab Shenzhen 518055 Guangdong Peoples R China Fuzhou Univ Coll Math & Comp Sci Key Lab Informat Secur Network Syst Fuzhou 350108 Fujian Peoples R China Univ Texas San Antonio Dept Informat Syst & Cyber Secur San Antonio TX 78249 USA

Searchable Symmetric Encryption (SSE), which enables users to search over encrypted data without decryption, has gained increasing attention from both academic and industrial fields. However, existing SSE schemes either have low search efficiency or cannot support multi-keyword search, dynamic updates, and result verification simultaneously. To solve these problems, we propose a Verifiable and Dynamic Multi-keyword Search (VDMS) scheme over encrypted data by using the bitmap and RSA accumulator, which provides multi-keyword search over encrypted data in an efficient, verifiable and updated way. The bitmap is used as a data structure to build the indexes, which improves the search efficiency and reduces the storage space of the indexes. The RSA accumulator and bitmap are combined to verify the correctness of results. Formal security analysis proves that our VDMS is adaptively secure against Chosen-keyword Attacks (CKA), and empirical experiments using a real-world dataset demonstrate that our VDMS is efficient and feasible in practical applications.

关键词： Searchable symmetric encryption multi-keyword search bitmap chosen-keyword attack

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Recent Progress in and Perspectives on Emerging Halide Superionic Conductors for All‑Solid‑state Batteries

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Electrochemical Energy Reviews 2023年第1期6卷 234-279页

作者： Kaiyong Tuo Chunwen Sun Shuqin Liu School of Chemical and Environmental Engineering China University of Mining&Technology(Beijing)Beijing 100083China 21C Innovation Laboratory Contemporary Amperex Technology Ltd.(21C LAB)Ningde 352100FujianChina

Rechargeable all-solid-state batteries(ASSBs)are considered to be the next generation of devices for electrochemical energy *** development of solid-state electrolytes(SSEs)is one of the most crucial subjects in the field of energy storage *** newly emerging halide SSEs have recently been intensively studied for application in ASSBs due to their favorable combination of high ionic conductivity,exceptional chemical and electrochemical stability,and superior mechanical *** this review,a critical overview of the development,synthesis,chemical stability and remaining challenges of halide SSEs is *** design strategies for optimizing the ionic conductivity of halide SSEs,such as element substitution and crystal structure design,are summarized in ***,the associated chemical stability issues in terms of solvent compatibility,humid air stability and corresponding degradation mechanisms are *** particular,advanced in situ/operando characterization techniques applied to halide-based ASSBs are *** addition,a comprehensive understanding of the interface issues,cost issues,and scalable processing challenges faced by halide-based ASSBs for practical application is ***,future perspectives on how to design high-performance electrode/electrolyte materials are given,which are instructive for guiding the development of halide-based ASSBs for energy conversion and storage.

关键词： Halide solid-state electrolytes Synthesis Ionic conductivity Chemical stability In situ/operando characterization All-solid-state batteries

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