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International Conference on reliability, Maintainability and Safety,ICRMS

作者： Xinman Wu Wenjin Zhang Yu Li Mingliang Suo Institute of Reliability Engineering National Key Laboratory of Science and Technology on Reliability and Environmental Engineering School of Reliability and Systems Engineering Beihang University Beijing

ISBN: (数字)9798350329988

ISBN: (纸本)9798350329995

With the rapid progress of technology, the application of unmanned aerial vehicles (UAVs) has become widespread in various civilian and military activities. The research on fault diagnosis during a flight is a critical step towards enhancing the safety of UAV systems. Swarm-inspired heuristic algorithms have attracted significant attention owing to their fast iteration speed and strong optimization capabilities. This paper proposes a UAV fault diagnosis method based on the slime mold algorithm (SMA) under the condition of imbalanced data, thus addressing the issue of low diagnostic accuracy caused by a significantly longer normal flight time compared to the fault flight time in UAV operations. Using a real-world dataset of UAV flight faults with multiple fault patterns, the proposed approach optimizes the parameters of the support vector machine through SMA, thereby improving the fault diagnosis performance during actual UAV flights.

关键词： Fault diagnosis Support vector machines Accuracy Heuristic algorithms Autonomous aerial vehicles Market research Data models Safety Particle swarm optimization Optimization

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reliability of system-of-systems: A new challenge of complex engineered systems

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Frontiers of engineering Management 2025年第2期12卷 434-441页

作者： Minghua LI Xing PAN Naimin ZHANG Pengwei HU Yuheng DANG China Academy of Launch Vehicle Technology Beijing 100076China School of Reliability and Systems Engineering Beihang UniversityBeijing 100191China National Key Laboratory of Reliability and Environmental Engineering Beijing 100191China System-of-Systems Center China Aerospace Science and Technology Group Co.Ltd.Beijing 100076China China Academy of Aerospace Standardization and Product Assurance Beijing 100071China

The emergence of systems-of-systems (SoS) brings new challenges for reliability research within the field of system-of-systems engineering (SoSE). In response, this study examines the requirements for measurement, evaluation, and design/testing of SoS reliability. Drawing on research practice in aerospace engineering, it outlines the concept of equipment SoS and proposes a corresponding research framework for equipment SoS reliability. By analyzing both the reliability demands of SoSE and the current research practice in aerospace equipment SoS, this study identifies several key challenges: Modeling of SoS and its reliability, network reliability in SoS, propagation and recovery of disturbances in SoS, reliability design and simulation methods, and reliability management in SoSE.

关键词： system-of-systems(SoS) architecture reliability network reliability resilience

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Investigation of Threshold Voltage Instability in p-GaN Gate HEMTs Under Surge Current Stress 17

Investigation of Threshold Voltage Instability in p-GaN Gate...

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17th IEEE International Conference on Solid-state and Integrated Circuit technology, ICSICT 2024

作者： Wang, Xiaoming Shi, Yu Zhou, David Zhi, Haizhao Xia, Yun Wan, Yuxi Sun, Ruize Chen, Xinghuan Chen, Wanjun Zhang, Bo Shenzhen Pinghu Laboratory Shenzhen518111 China University of Electronic Science and Technology of China State Key Laboratory of Electronic Thin Films and Integrated Devices Chengdu610054 China Institute of Electronic and Information Engineering of UESTC in Guangdong Dongguan523808 China China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou510610 China

ISBN: (纸本)9798350361834

In this paper, the threshold voltage (V T H ) instability mechanism in p-GaN gate HEMTs under surge current stress is revealed. The significant positive shift of V TH (Δ V TH ), which has a strong Ipeak (i.e., the peak value of surge current) dependence, is observed after the surge current passes through the device. As the Ipeak exceeds a critical value (I critical ), the Δ V TH will saturate and may decrease. Furthermore, the I critical varies with the V GS , initial gate leakage current (I g , init ), and substrate termination. It is suggested that electron trapping and hole trapping would take place during the stress. The electron trapping is more dependent on the current level, while the hole trapping is more dependent on the surge voltage, mainly the gate-to-channel voltage (V GC ). It is confirmed by mix-mode simulation and further experiments. © 2024 IEEE.

关键词： Gallium nitride

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Necessity and Optimal Design of Magnetic Shielding Structure for Leakage Current Sensors 7

Necessity and Optimal Design of Magnetic Shielding Structure...

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7th IEEE International Electrical and Energy Conference, CIEEC 2024

作者： Yin, Pengbo Liu, Yan Liu, Jianben Li, Huiqiang Hu, Wei Gao, Lianlian State Key Laboratory of Power Grid Environmental Protection China Electric Power Research Institute Wuhan China Harbin University of Science and Technology School of Electric and Electronic Engineering Harbin China

ISBN: (纸本)9798350359558

Leakage current is inextricably linked to the insulation state of power equipment, leakage current refers to the current formed inside the insulation and on the surface of the insulation between the high potential and the low potential under the condition of applied voltage. Leakage current is an essential basic parameter for the perception of insulation state of power equipment, and to improve the reliability of the perception of insulation state of power equipment, it is necessary to ensure that the leakage current measurement results are accurate, stable and reliable. Therefore, it is of great significance to study the magnetic shielding structure of microcurrent sensors and improve the shielding structure's ability to resist the interference of industrial frequency magnetic field. In this paper, by optimizing the design of magnetic shield structure, increasing the thickness of magnetic shield extension structure and magnetic shield gap, the shielding efficiency of the shielding device can be effectively enhanced. Through the study of micro-current sensors in the complex system substation environment by the external magnetic field interference on the influence of its working magnetic field characteristics, aimed at solving the micro-current sensors in the face of industrial frequency magnetic field interference in the weak anti-interference ability of technical problems. © 2024 IEEE.

关键词： Insulation

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Mechanical behavior and damage constitutive model of sandstone under hydro-mechanical (H-M) coupling

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International Journal of Mining science and technology 2024年第6期34卷 837-853页

作者： Tao Tan Chunyang Zhang Yanlin Zhao Xiaoshuang Li School of Resources and Environmental Engineering Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Safety and Health in Metal Mines Maanshan 243000China Sinosteel Maanshan General Institute of Mining Research Co. Ltd.Maanshan 243000China School of Resource&Environment and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Urban Construction Changzhou UniversityChangzhouJiangsu 213164China

Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-C) model has become the focus of attention. Considering the inadequacy of the current research on rock strength parameters,energy evolution characteristics and D-C model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of characteristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-Coulomb(M-C) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution characteristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage efficiency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-C models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-C models have high reliability, and can characterize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-C models

关键词： H-M coupling Water-saturated sandstone Mechanical mechanism Energy evolution D-C model

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Coherence analysis of laser pulses based on an external cavity circulation 1

Coherence analysis of laser pulses based on an external cavi...

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1st International Conference on Spatial Atmospheric Marine environmental Optics, SAME 2023

作者： Xu, He Sun, Difeng Li, Jianbing National University of Defense Technology State Key Laboratory of Complex Electromagnetic Environmental Effects on Electronics and Information System College of Electronic Science and Technology Hunan Changsha410073 China Northwest Institute of Nuclear Technology Shaanxi Xi’an710024 China

ISBN: (纸本)9781510666337

By constructing an external circulating cavity to provide sufficient delay that equals a multiple of pulse repetition time, a method with a fixed experimental configuration is proposed to measure the coherence length of both single-frequency and microwave-modulated optical pulses. This method can accurately determine the number of coherent pulses as well as distinguish the coherence states: complete coherence, partial coherence and complete incoherence. In addition, all desired coherence phenomena are obtained by one-time measurement, avoiding other operations like frequent fiber-cutting or devices-reconnection in previous methods. Simulation results show that the coherence length of the dual-frequency laser is periodically extended by the reciprocal of the frequency difference, and the random jitter of pulse propagation time would result in obvious measurement errors via perturbing coherence status. © 2023 SPIE.

关键词： Random errors

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When Neural Code Completion Models Size up the Situation: Attaining Cheaper and Faster Completion through Dynamic Model Inference 24

When Neural Code Completion Models Size up the Situation: At...

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44th ACM/IEEE International Conference on Software engineering, ICSE 2024

作者： Sun, Zhensu Du, Xiaoning Song, Fu Wang, Shangwen Li, Li Beihang University Beijing China Monash University Melbourne VIC Australia Institute of Software Chinese Academy of Sciences State Key Laboratory of Computer Science Beijing China National University of Defense Technology Changsha China Beihang University Beijing Yunnan Key Laboratory of Software Engineering China

ISBN: (纸本)9798400702174

Leveraging recent advancements in large language models, modern neural code completion models have demonstrated the capability to generate highly accurate code suggestions. However, their massive size poses challenges in terms of computational costs and environmental impact, hindering their widespread adoption in practical scenarios. Dynamic inference emerges as a promising solution, as it allocates minimal computation during inference while maintaining the model's performance. In this research, we explore dynamic inference within the context of code completion. Initially, we conducted an empirical investigation on GPT-2, focusing on the inference capabilities of intermediate layers for code completion. We found that 54.4% of tokens can be accurately generated using just the first layer, signifying significant computational savings potential. Moreover, despite using all layers, the model still fails to predict 14.5% of tokens correctly, and the subsequent completions continued from them are rarely considered helpful, with only a 4.2% Acceptance Rate. These findings motivate our exploration of dynamic inference in code completion and inspire us to enhance it with a decision-making mechanism that stops the generation of incorrect code. We thus propose a novel dynamic inference method specifically tailored for code completion models. This method aims not only to produce correct predictions with largely reduced computation but also to prevent incorrect predictions proactively. Our extensive evaluation shows that it can averagely skip 1.7 layers out of 16 layers in the models, leading to an 11.2% speedup with only a marginal 1.1 % reduction in ROUGE- L. © 2024 ACM.

关键词： Forecasting

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Comparison of dominant frequency attenuation of blasting vibration for different charge structures

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Journal of Rock Mechanics and Geotechnical engineering 2022年第2期14卷 448-459页

作者： Pengchang Sun Wenbo Lu Junru Zhou Xincheng Huang Ming Chen Qi Li State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China School of Resource and Environmental Engineering Wuhan University of Science and TechnologyWuhan430081China Changjiang Institute of Survey PlanningDesign and ResearchWuhan430010China

Dominant frequency attenuation is a significant concern for frequency-based criteria of blasting vibration *** is necessary to develop a concise and practical prediction equation describing dominant frequency *** this paper,a prediction equation of dominant frequency that accounts for primary parameters influencing the dominant frequency was proposed based on theoretical and dimensional *** blasting experiments were carried out in the Chiwan parking lot for collecting blasting vibration data used to conduct regression analysis of the proposed prediction *** fitting equations were further adopted to compare the reliability of three different types of dominant frequencies in the proposed equation and to explore the effects of different charge structures on the dominant frequency *** apparent frequency proved to be more reliable to express the attenuation law of the dominant *** reliability and superiority of the proposed equation employing the apparent frequency were verified by comparison with the other five prediction *** smaller blasthole diameter or decoupling ratio leads to the higher initial value and corresponding faster attenuation of the dominant *** blasthole diameter has a greater influence on the dominant frequency attenuation than the decoupling ratio *** the charge structures applied in the experiments,the charge structure with decoupling ratio of 1.5 and blasthole diameter of 48 mm results in the greatest initial value and corresponding fastest attenuation of the dominant frequency.

关键词： Dominant frequency Blasting vibration Attenuation law Prediction equation Charge structures

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Crustal thickness,V_(P)/V_(S) ratio,and shear wave velocity structures beneath Myanmar and their tectonic implications

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Earthquake Research Advances 2022年第1期2卷 15-21页

作者： Lay Nwe Zigen Wei Zhiwei Li Feng Bao Xuelei Li Jintao Hu State Key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430077China Science and Technology on Reliability and Environmental Engineering Laboratory Beijing Institute of Spacecraft Environment EngineeringBeijing100094China School of Science Hunan University of Technology and BusinessChangsha410205China Department of Meteorology and Hydrology Ministry of Transport and CommunicationsMyanmar Hebei University of Engineering Handan056009China

The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision *** successively performed H-k stacking of the receiver function and joint inversion of the receiver function and surface wave dispersion to invert the crustal thickness(H),shear wave velocity(V_(S)),and the V_(P)/V_(S) ratio(k)beneath nine permanent seismic stations in Myanmar.H was found to increase from 26 km in the south and east of the study area to 51 km in the north and west,and the V_(P)/V_(S) ratio was complex and *** differences in the crust were observed for different tectonic *** the Indo-Burma Range,the thick crust(H~51 km)and lower velocities may be related to the accretionary wedge from the Indian *** the Central Myanmar Basin,the thin crust(H=26.9-35.5 km)and complex V_(P)/V_(S) ratio and V_(S) suggest extensional *** the Eastern Shan Plateau,the relatively thick crust and normal V_(P)/V_(S) ratio are consistent with its location along the western edge of the rigid Sunda Block.

关键词： Myanmar Crustal thickness VP/VSratio Shear wave velocity Receiver function Surface wave dispersion

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Sulfate diffusion in coal pillar:experimental data and prediction model

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International Journal of Coal science & technology 2023年第2期10卷 117-128页

作者： Min Wang Xun Xi Qifeng Guo Jiliang Pan Meifeng Cai Shangtong Yang School of Resource Environment and Safety Engineering University of South ChinaHengyang 421001China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Water Resource Protection and Utilization in Coal Mining China Energy InvestmentBeijing 100000China Department of Civil and Environmental Engineering University of StrathclydeGlasgow G11XJUK

The stability of coal pillar dams is crucial for the long-term service of underground reservoirs storing water or ***-cal damage of coal dams induced by ions-atttacking in coal is one of the main reasons for the premature failure of coal ***,the diffusion process of harmful ions in coal is far from clear,limiting the reliability and durability of coal dam *** paper investigates sulfate diffusion in coal pillar through experimental and analytical *** specimens are prepared and exposed to sulfate solutions with different *** sulfate concentrations at different locations and time are *** on experimental data and Fick's law,the time-dependent surface concentration of sulfate and diffusion coefficient are determined and ***,an analytical model for predicting sulfate diffusion in coal pillar is developed by considering dual time-dependent characteristics and Laplace *** comparisons with experimental data,the accuracy of the analytical model for predicting sulfate diffusion is ***,sulfate diffusions in coal dams for different concentrations of sulfate in mine water are *** has been found that the sulfate concen-tration of exposure surface and diffusion coefficient in coal are both time-dependent and increase with *** Fick's law is not able to predict the sulfate diffusion in coal pillar due to the dual time-dependent *** sulfate attacking makes the coal dam a typical heterogeneous gradient *** sulfate concentrations 0.01-0.20 mol/L in mine water,it takes almost 1.5 and 4 years for sulfate ions to diffuse 9.46 and 18.92 m,*** experimental data and developed model provide a practical method for predicting sulfate diffusion in coal pillar,which helps the service life design of coal dams.

关键词： Sulfate diffusion Coal dam-Underground reservoirs Time-dependent Analytical model Chemical damage

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