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SSRN 2023年

作者： Zhang, Hang Wen, Binrong Tian, Xinliang Li, Xin Dong, Yehong Wang, Manchang Peng, Zhike State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China SJTU Yazhou Bay Institute of Deepsea Science and Technology Sanya57200 China CSIC Offshore Wind Power Co. Ltd Chongqing401123 China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China School of Mechanical Engineering Ningxia University Yinchuan750021 China

Compared to the onshore wind turbine, the floating offshore wind turbine (FOWT) suffers from worse environmental loads during its operation, leading to complicated dynamic responses. The excessive vibration would be potentially harmful to the structure safety and reliability. The Tuned Mass Damper (TMD) is regarded as a promising vibration mitigation device and has been popularized in FOWTs recently. However, the effects on vibration mitigation of TMD is still difficult to investigate due to the flexibility of FOWT system and the varied excitations. This paper presents an experimental study on the mitigation of dynamic responses of an FOWT under complex environmental loads. According to the tower vibration characteristics, a highly adaptive TMD is designed and constructed. The integrated FOWT-TMD testing system is set up. Then, extensive tests are conducted with different offshore environments and TMD operational states. The results indicate that the tower-top acceleration amplitude and tower-base bending moment of FOWT are effectively reduced by using TMD, with the reduction of 7.8% and 8.8% in survival condition respectively. It will serve to verify the effectiveness of TMD and lay the foundation for experimentation techniques on advanced FOWT controllers. © 2023, The Authors. All rights reserved.

关键词： Dynamic response

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Structural Optimization of Photoacoustic Transducer with Pdms/Csnps Nanocomposite for Laser-Induced Nonlinear Surface Wave and its Application in Fatigue Crack Detection

SSRN

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SSRN 2023年

作者： Yao, Zhijun Li, Yehai Lv, Gaolong Chen, Dan Yang, Jian Guo, Shifeng Shenzhen Key Laboratory of Smart Sensing and Intelligent Systems Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Institute of Intelligent Manufacturing Technology Shenzhen Polytechnic Shenzhen518055 China Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Ningbo China Ningbo315100 China

Laser ultrasonics is a promising non-contact inspection technique but faces the challenges of low signal-to-noise ratio and low amplitude under the non-destructive thermoelastic regime. In this paper, an ultrasonic surface wave modulation method based on laser ultrasonics and photoacoustic transducer (PAT) is proposed and combined with nonlinear wave mixing technique to achieve non-contact detection of fatigue crack. The PAT comprised of candle soot nanoparticles and polydimethylsiloxane (PDMS) as well as a line-arrayed laser source modulated by a slit mask are firstly introduced to generate narrowband surface wave with high intensity and SNR under the thermoelastic regime. The thicknesses of the PDMS layers of PAT are thereafter optimized by analytical, numerical and experimental investigations to acquire narrowband surface wave with pure fundamental frequency component. Two modulated ultrasonic surface waves with frequencies of 2.1 MHz and 2.9 MHz are excited on a fatigued aluminum plate to generate nonlinear mixed components, and the ultrasonic responses over the fatigue crack regions are acquired by using a scanning laser Doppler vibrometer. The localization of fatigue crack with microscale is eventually acquired by mapping the nonlinear parameter of the mixed components, which proves it a reliable and nondestructive technique to inspect the fatigue crack. © 2023, The Authors. All rights reserved.

关键词： Transducers

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Effect of water states on mechanical properties of cellulose insulation paper: A molecular dynamics simulation study 7

Effect of water states on mechanical properties of cellulose...

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7th IEEE International Conference on High Voltage Engineering and Application, ICHVE 2020

作者： Dan, Linyang Huang, Zhengyong Wang, Qiang Li, Jian Chen, Gang He, Jianfeng State Key Laboratory of Power Transmission Equipment System Security and New Technology School of Electrical Engineering Chongqing University Chongqing China

ISBN: (纸本)9781728155111

A commonly accepted serious drawback for cellulose paper is high water susceptibility, making it susceptible to moisture attack. In this study, six fully atomic cellulose models with different water contents were constructed to disclose the effects of water states on the mechanical properties of cellulose. Results showed that at low water concentrations, almost all water molecules belong to the bound state. With increasing water content, free water gradually prevails since the hydrophilic sites of cellulose have been occupied. Furthermore, free water has a strong capacity of the molecular movement to diffuse in amorphous cellulose, while bound water is fixed by cellulose. For the mechanical properties, both the young's modulus and elastic modulus are slightly increased at low water concentrations, but once the water content exceeds 5%, they start to drop dramatically. This phenomenon is ascribed to the result of the competition between free water and bound water. © 2020 IEEE.

关键词： Cellulose

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Distributed Energy Optimization for Mobile Networks Using Potential Games

Distributed Energy Optimization for Mobile Networks Using Po...

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IEEE Internatonal Conference on Mobile Adhoc and Sensor systems (MASS)

作者： Zhizongkai Wang Hanfei Wang Zhongji Wang Yilin Xiao Yunzhi Zhao Xiaowen Li Xufeng Chen Lin Gao Fen Hou Jianwei Huang School of Electronics and Information Engineering and the Guangdong Provincial Key Laboratory of Aerospace Communication and Networking Technology Harbin Institute of Technology Shenzhen Guangdong P.R. China School of Science and Engineering Shenzhen Institute of Artificial Intelligence and Robotics for Society Shenzhen Key Laboratory of Crowd Intelligence Empowered Low-Carbon Energy Network and CSIJRI Joint Research Centre on Smart Energy Storage The Chinese University of Hong Kong Shenzhen Guangdong P.R. China Department of Electrical and Computer Engineering State Key Laboratory of IoT for Smart City University of Macau Macau SAR P.R. China Huawei Technologies P.R. China

ISBN: (数字)9798350363999

ISBN: (纸本)9798350364002

The rapid advancement of information and communication technology (ICT) has made the industry a significant contributor to global carbon emissions. As the foundation of ICT, next-generation mobile communication networks aim to be more powerful and energy-efficient. However, optimizing energy efficiency in real networks is challenging due to large-scale, multi-layer control variables and the dynamic environment. This paper addresses the energy efficiency optimization problem from a network perspective by controlling cross-layer variables including both cell activation status and cell priority, to minimize overall network energy consumption while ensuring user quality-of-experience, which poses an NP-hard mixed-integer nonlinear programming problem. To tackle this, we propose a non-cooperative game where each cell acts as a player, optimizing its activation status and reference signal transmission power (determining its priority). We show that the game is a potential game, guaranteeing the existence of Nash equilibrium and the convergence of simple distributed algorithms towards Nash equilibrium. We further show that the Nash equilibrium points of the game can (but not always) reach the global optimal energy efficiency. Simulation results show that our proposed method can reduce the total system cost (including both energy consumption cost and user experience loss) by up to 28% compared to existing methods in the literature. Moreover, the performance loss of our proposed method, compared to the global optimal solution, is less than 13.7%. In summary, this work offers a realistic network model, introduces a novel game-based method, and provides extensive performance evaluation, making a significant contribution to both industry and academia.

关键词： Industries Energy consumption Costs Simulation Games Nash equilibrium Energy efficiency Information and communication technology Distributed algorithms Optimization

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Augmented Box Replay: Overcoming Foreground Shift for Incremental Object Detection

arXiv

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arXiv 2023年

作者： Liu, Yuyang Cong, Yang Goswami, Dipam Liu, Xialei van de Weijer, Joost State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences China University of Chinese Academy of Sciences China South China University of Technology China Computer Vision Center Barcelona Spain VCIP CS Nankai University China Department of Computer Science Universitat Autònoma de Barcelona Spain

In incremental learning, replaying stored samples from previous tasks together with current task samples is one of the most efficient approaches to address catastrophic forgetting. However, unlike incremental classification, image replay has not been successfully applied to incremental object detection (IOD). In this paper, we identify the overlooked problem of foreground shift as the main reason for this. Foreground shift only occurs when replaying images of previous tasks and refers to the fact that their background might contain foreground objects of the current task. To overcome this problem, a novel and efficient Augmented Box Replay (ABR) method is developed that only stores and replays foreground objects and thereby circumvents the foreground shift problem. In addition, we propose an innovative Attentive RoI Distillation loss that uses spatial attention from region-of-interest (RoI) features to constrain current model to focus on the most important information from old model. ABR significantly reduces forgetting of previous classes while maintaining high plasticity in current classes. Moreover, it considerably reduces the storage requirements when compared to standard image replay. Comprehensive experiments on Pascal-VOC and COCO datasets support the state-of-the-art performance of our model 1 © 2023, CC BY.

关键词： Object detection

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CrashTranslator: Automatically Reproducing Mobile Application Crashes Directly from Stack Trace

arXiv

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arXiv 2023年

作者： Huang, Yuchao Wang, Junjie Liu, Zhe Wang, Yawen Wang, Song Chen, Chunyang Hu, Yuanzhe Wang, Qing Institute of Software Chinese Academy of Sciences Beijing China York University Toronto Canada Monash University Melbourne Australia State Key Laboratory of Intelligent Game Institute of Software CAS China Science and Technology on Integrated Information System Laboratory Institute of Software CAS China University of Chinese Academy of Sciences China

Crash reports are vital for software maintenance since they allow the developers to be informed of the problems encountered in the mobile application. Before fixing, developers need to reproduce the crash, which is an extremely time-consuming and tedious task. Existing studies conducted the automatic crash reproduction with the natural language described reproducing steps. Yet we find a non-neglectable portion of crash reports only contain the stack trace when the crash occurs. Such stack-trace-only crashes merely reveal the last GUI page when the crash occurs, and lack step-by-step guidance. Developers tend to spend more effort in understanding the problem and reproducing the crash, and existing techniques cannot work on this, thus calling for a greater need for automatic support. This paper proposes an approach named CrashTranslator to automatically reproduce mobile application crashes directly from the stack trace. It accomplishes this by leveraging a pre-trained Large Language Model to predict the exploration steps for triggering the crash, and designing a reinforcement learning based technique to mitigate the inaccurate prediction and guide the search holistically. We evaluate CrashTranslator on 75 crash reports involving 58 popular Android apps, and it successfully reproduces 61.3% of the crashes, outperforming the state-of-the-art baselines by 109% to 206%. Besides, the average reproducing time is 68.7 seconds, outperforming the baselines by 302% to 1611%. We also evaluate the usefulness of CrashTranslator with promising results. Copyright © 2023, The Authors. All rights reserved.

关键词： Application programs

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Electric Field and Temperature Distribution Analysis For 110 kV Transformer After Replacing Three-element Mixed Insulating Oil

Electric Field and Temperature Distribution Analysis For 110...

引用

International Conference on High Voltage Engineering and Application, ICHVE

作者： Jian Hao Junyi Zhang Jie Wu Xiong Liu Wei Qin Qian Wang State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China State Grid Chongqing Electric Power Co. Chongqing Electric Power Research Institute Chongqing China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407519

Power transformer play a central role in energy conversion in the process of power transmission and distribution. It is the key equipment for the safe operation of power grid. In order to study the electric field and temperature distribution characteristics of the transformer after replacing the three-element mixed insulating oil, this paper takes mineral oil as a reference and analyzes the electric field and thermal field of a 110 kV three-winding power transformer based on multi-physics simulation method. Results show that after replacing the three-element mixed insulating oil, the maximum field strength of the low-voltage windings of the two oil-paper systems is located in the middle and lower parts, and the maximum field strength of the high-voltage windings is located at the bottom. The maximum electric field strengths of the high-voltage winding and low-voltage winding in the mineral are 4.079 kV/mm and 3.814 kV/mm, and the voltage at the same position in the three-element mixed insulating oil transformer are 4.162 kV/mm and 4.041 kV/mm. Compared with the mineral insulating oil, the electric field of the mixed insulating oil is increased about 0.1kV/mm. After replacing the ternary mixed insulating oil, under the conditions of load ratios of 1 and 0.5, the maximum temperature of the low-voltage winding of the transformer has increased by about 8K and 6K respectively compared with that before the replacement. This study provides a theoretical basis for the further application of three-element mixed insulating oil in high-voltage transformers.

关键词： Temperature distribution Low voltage Oils Windings High-voltage techniques Oil insulation Minerals

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PCG: Mitigating Conflict-based Cache Side-channel Attacks with Prefetching

arXiv

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arXiv 2024年

作者： Jiang, Fang Tong, Fei Wang, Hongyu Cheng, Xiaoyu Zhou, Zhe Ling, Ming Mao, Yuxing The School of Cyber Science and Engineering Southeast University Jiangsu Nanjing China Jiangsu Province Engineering Research Center of Security for Ubiquitous Network China The Purple Mountain Laboratories Jiangsu Nanjing China The State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Wiscom System Co. LTD China The School of Integrated Circuits Southeast University Jiangsu Nanjing China

To defend against conflict-based cache side-channel attacks, cache partitioning or remapping techniques were proposed to prevent set conflicts between different security domains or obfuscate the locations of such conflicts. But such techniques complicate cache design and may result in significant performance penalties. Therefore, there have been lightweight prefetching-based schemes proposed to introduce noise to confuse attackers’ observation. However, we have validated experimentally that relying on prefetching to only introduce noise is insufficient, as attackers can still reliably distinguish the victim’s cache accesses. This paper proposes a novel prefetching-based scheme, called PCG. It combines adding victim-irrelevant cache occupancy changes and reducing victim-relevant cache occupancy changes to disrupt attackers by generating noisy and indistinguishable cache access patterns. Additionally, PCG can either work independently or seamlessly be integrated with most of the commonly used prefetchers. We have implemented and evaluated PCG in both gem5 and the open-source RISC-V core BOOMv3. The evaluation results show the PCG’s robust security superior to the existing solutions, while without resulting in significant performance degradation. According to the evaluation based on the SPEC CPU 2017 benchmark suite, PCG even shows an average performance improvement of about 1.64%. Moreover, it incurs only 1.26% overhead on hardware resource consumption. Copyright © 2024, The Authors. All rights reserved.

关键词： Side channel attack

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Study on Ice - Melting Model and Experimental Verification of Conductor W Ith Carr Ying Direct Current

SSRN

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SSRN 2022年

作者： Dong, Bingbing Jiang, Xingliang School of Electrical Engineering and Automation Hefei University of Technology Hefei230009 China State Key Laboratory of Power Transmission Equipment & System Security New Technology College of Electrical Engineering Chongqing University Chongqing400044 China

Atmospheric icing of power lines is one of the most frequent causes of power system interruption, resulting in large-scale mechanical failures and electrical decrease accidents. As o... 详细信息

Atmospheric icing of power lines is one of the most frequent causes of power system interruption, resulting in large-scale mechanical failures and electrical decrease accidents. As one of the widely used de-icing strategies, accurately predicting the melting current and the melting time is persistent research problem. Based on the ice-melting test of icing conductors with carrying direct current, an ice-melting model considering the thermal balance performance is developed. The influence of various parameters on the ice-melting period are considered, such as wind speed, air temperature, ice thickness and current density. And the increase of wind velocity has an obvious constraint effect on ice-melting of conductors evidently. Both theory and tests proved that the new model is valuable for the calculation of ice-melting on conductors. The theoretical reference for the design, operation and maintenance of anti-icing and mitigation with power infrastructure can be provided. © 2022, The Authors. All rights reserved.

关键词： Ice

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Controlled Propulsion of Asymmetric Janus Microdimer Swimmers under Rotating Magnetic Fields

Controlled Propulsion of Asymmetric Janus Microdimer Swimmer...

引用

IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Shimin Yu Tianlong Li Shaopeng Wu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Harbin Institute of Technology Harbin China

ISBN: (数字)9781728151694

ISBN: (纸本)9781728151700

Untethered micro-/nanorobots at low Reynolds numbers present significant potential in biomedical applications as result of their enhanced power, remote actuation, and versatility. Herein, a highly efficient asymmetric Janus microdimer swimmer propelled by a rotating uniform magnetic field was investigated experimentally. The asymmetric microdimers can achieve speed of 98 μm·s -1 at 20 Hz and 5 mT. Besides, the controllable and flexible motility performance of microdimer motors can be easily obtained by adjusting the magnetic field. Such an asymmetric Janus microdimer swimmer is highly promising in a variety of realistic micro-/nanoscale scenarios.

关键词： Industrial electronics Navigation Conferences Propulsion Nanoscale devices Trajectory Magnetic fields

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