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Acoustic propagation uncertainty in internal wave environments using an ocean-acoustic joint model

Chinese Physics B 2023年第3期32卷 308-319页

作者：高飞徐芳华李整林秦继兴章沁雅 Department of Earth System Science Ministry of Education Key Laboratory of Earth System ModelingInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China Naval Research Institute Tianjin 300061China School of Ocean Engineering and technology Sun Yat-Sen UniversityZhuhai 519000China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China

An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave *** internal waves are numerically produced by tidal forcing over a continental slope using an ocean *** parameters(i.e.,internal wave,source depth,and water depth)contribute to the dynamic waveguide environments,and result in stochastic sound *** sensitivity of the transmission loss(TL)to environment parameters,statistical characteristics of the TL variation,and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method,the Monte Carlo sampling,and the coupled normal mode theory,*** results show that the TL is most sensitive to the source depth in the near field,resulted from the initial amplitudes of higher-order modes;while in middle and far fields,the internal waves are responsible for more than 80%of the total acoustic propagation *** addition,the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.

关键词： acoustic propagation uncertainty ocean-acoustic joint model internal wave sensitivity analysis

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Autonomous planning and control strategy for space manipulators with dynamics uncertainty based on learning from demonstrations

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Science China(Technological Sciences) 2021年第12期64卷 2662-2675页

作者： LI ChongYang LI ZhiQi JIANG ZaiNan CUI ShiPeng LIU Hong CAI HeGao State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

Autonomous planning is a significant development direction of the space manipulator,and learning from demonstrations(LfD)is a potential strategy for complex tasks in the ***,separating control from planning may cause large torque fluctuations and energy consumptions,even instability or danger in control of space manipulators,especially for the planning based on the human ***,we present an autonomous planning and control strategy for space manipulators based on LfD and focus on the dynamics uncertainty problem,a common problem of actual *** process can be divided into three stages:firstly,we reproduced the stochastic directed trajectory based on the Gaussian process-based LfD;secondly,we built the model of the stochastic dynamics of the actual manipulator with Gaussian process;thirdly,we designed an optimal controller based on the dynamics model to obtain the improved commanded torques and trajectory,and used the separation theorem to deal with stochastic characteristics during *** evaluated the strategy with locating pre-screwed bolts experiment by Tiangong-2 manipulator system on the *** result showed that,compared with other strategies,the strategy proposed in this paper could significantly reduce torque fluctuations and energy consumptions,and its precision can meet the task requirements.

关键词： space manipulator optimal control dynamics uncertainty learning from demonstrations

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Repaired morphology of CO_(2)laser rapid ablation mitigation of fused silica and its influence on downstream light modulation

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Science China(Technological Sciences) 2022年第5期65卷 1116-1126页

作者： TAN Chao ZHAO LinJie CHEN MingJun CHENG Jian ZHANG Yu ZHANG Jiong YANG Hao YIN ZhaoYang State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin150001China Department of Mechanical Engineering National University of SingaporeSingapore117575Singapore

The threat of cascading damage to downstream components caused by the light modulation intensification of laser repaired morphology on the surface of fused silica optics cannot be ignored in high-power laser *** paper uses the angular spectrum diffraction theory based on the analysis of repaired surface morphology of CO_(2)laser rapid ablation mitigation to study the influence of different repaired morphologies on the downstream 355 nm laser *** show that the arc-shaped laser processing lines on the repaired surface are formed by the residual height superposition of the material after laser scanning of two adjacent layers,and the short-pulse laser can substantially suppress the heat-affected zone of the repaired *** offaxis ring caustic and on-axis hotspot are sequentially generated in the downstream modulated light fields of the conical repaired sites with different diameters.A secondary peak with modulation larger than 3 emerges downstream of the modulation ***,the maximum modulation and the secondary peak increase with the diameter and cone angle of the repaired site,and the position of the secondary peak appears farther away from the rear *** modulations of three repaired sites with cone angles of 15°,20°,and 25°can finally be stabilized below ***,the downstream optics should be installed far away from the positions where the maximum modulation and the secondary peak ***,the maximum value and the secondary peak of the downstream light modulation of double repaired sites are larger than that of the single repaired site,and both rise as the repaired sizes ***,large-scale and large-size repairing of multiple surface damages in the same area should be avoided in the laser repairing of fused silica.

关键词： fused silica laser repairing morphology light modulation secondary peak double repaired sites

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Indoor Confined Space: GNSS Multi-Frequency Location Method based on Pursuit Principle 14

Indoor Confined Space: GNSS Multi-Frequency Location Method ...

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14th International Conference on Indoor Positioning and Indoor Navigation - Work-in Progress Papers, IPIN-WiP 2024

作者： Heng, Zhang Qing, Wang Lu, Huang Yaning, Li Jianqiang, Cheng Shiyuan, Liu The 54th Research Institute of China Electronics Technology Group Corporation China State Key Laboratory of Satellite Navigation System and Equipment Technology China

Aiming at the problem that it is difficult to carry out effective high-precision positioning in the complex and limited indoor space environment, this paper proposes an indoor limited space GNSS multi-frequency PSO (Particle Swarm Optimization) positioning method. This algorithm effectively solves the positioning technical problems which caused by inaccurate indoor spatial signal ranging. further we analyze the factors that affect the performance of the positioning algorithm. Compared to our team's existing KPI-based doppler positioning algorithm, the algorithm in this paper improves the problem of inaccurate range measurement, which caused by frequent cycle slips of signal loss. Through multi-frequency coordination and local optimization processing, the stability and continuity of indoor high-precision positioning are improved. The simulation results of semi-measured data show that the accuracy of the positioning algorithm in this paper is equivalent to that of the existing algorithm. When some signals are temporarily lost and refilled, the performance of this algorithm is better than that of the existing algorithm, and it has better continuity and robustness. © 2024 Copyright for this paper by its authors.

关键词： Particle swarm optimization (PSO)

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Axial and radial electromagnetic-vibration characteristics of converter transformer windings under current harmonics

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High Voltage 2023年第3期8卷 477-491页

作者： Peiyu Jiang Zhanlong Zhang Zijian Dong Yu Yang Zhicheng Pan Jun Deng State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingShapingbaChina Maintenance&Test Centre EHVChina Southern Power GridGuangzhouGuangdongChina

The winding current harmonic content of converter transformer in operation is ***,affected by harmonics,the radial vibration characteristics are quite different from the power transformer,structural loosening and deformation caused by winding vibration are more ***,in view of the influence of current harmonics on axial and radial vibrations,this study builds a 3D winding electromagnetic vibration finite element simulation model,analyses the components and contents of current harmonics,compares the leakage flux and vibration distribution under the fundamental,harmonic and superimposed *** correlation relationship between the harmonic components and axial and radial vibration characteristics is obtained,and the vibration measurement test of±800 kV converter transformer in operation is carried out to verify the correctness of the analysis *** results show that the winding radial vibration amplitude will exceed the axial vibration affected by *** importantly,under the superposition of the fundamental,5th and 7th harmonic current,the vibration contribution of the converter transformer tank is mainly radial vibration,and the vibration dominant frequency is shifted from 100 Hz under the fundamental current to 400 Hz.

关键词： winding harmonics harmonic

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Significantly enhanced flashover voltage of epoxy in vacuum by graded surface roughness modification

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High Voltage 2023年第5期8卷 997-1010页

作者： Inzamam Ul Haq Feipeng Wang Shakeel Akram Muneeb Ahmed Muhammad Tariq Nazir State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjingChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina School of Engineering RMIT UniversityMelbourneVictoriaAustralia

The flashover strength of epoxy(EP)insulations in the High voltage direct current applications of future energy grids can be improved by tailoring their surface *** work aims to improve the DC surface flashover characteristics of EP after being treated with sandpaper of different *** with virgin EP and homogenously modified EP considering varying surface roughness(R_(a)=0.54,3.16,5.24,and 8.35μm)are *** experimental characterisations,such as water contact angle,surface intrinsic conductivity,surface voltages,flashover strength,and trap distributions are conducted and evaluated to analyse the difference between virgin and treated ***,based on the obtained experimental results of homogenously treated EP and theoretical analysis,the concept of surface functionally graded materials(SFGMs)is put *** flashover voltages of homogenously treated EP are augmented significantly compared to virgin EP regardless of the voltage polarity and enhanced by enhancing the surface *** sample T_(Model‐C) with SFGM design shows a 45.02%and 43.75%improvement in the negative and positive flashover voltages than that of the virgin *** the end,COMSOL simulations are conducted to justify the experimental findings and to analyse the difference between virgin and modified samples in terms of electric field distribution.

关键词： flash graded roughness

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Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

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Research 2024年第1期2023卷 209-236页

作者： Feng Tian Zhongya Pang Shen Hu Xueqiang Zhang Fei Wang Wei Nie Xuewen Xia Guangshi Li Hsien-Yi Hsu Qian Xu Xingli Zou Li Ji Xionggang Lu State Key Laboratory of Advanced Special Steel&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai University99#Shangda RoadShanghai 200444China Center for Hydrogen Metallurgy Technology Shanghai UniversityShanghai 200444China State Key Laboratory of ASIC and System School of MicroelectronicsFudan University220#Handan RoadShanghai 200433China School of Energy and Environment Department of Materials Science and EngineeringCity University of Hong KongKowloon TongHong KongChina

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science ***,considered a promising strategy,has been explored to produce silicon due to prominent advantages:(a)high electricity utilization efficiency;(b)low-cost silica as a raw material;and(c)tunable morphologies and structures,including films,nanowires,and *** review begins with a summary of early research on the extraction of silicon by *** has been placed on the electro-deoxidation and dissolution–electrodeposition of silica in chloride molten salts since the 21st century,including the basic reaction mechanisms,the fabrication of photoactive Si films for solar cells,the design and production of nanoSi and various silicon components for energy conversion,as well as storage ***,the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are *** this basis,the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed,which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

关键词： directions electrodeposition electricity

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A Two-stage Stochastic Mixed-integer Programming Model for Resilience Enhancement of Active Distribution Networks

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Journal of Modern Power systems and Clean Energy 2023年第1期11卷 94-106页

作者： Hongzhou Chen Jian Wang Jizhong Zhu Xiaofu Xiong Wei Wang Hongrui Yang State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China South China University of Technology Guangzhou 510641China Electric Power Research Institute State Grid Chongqing Electric Power CompanyChongqing 401123China IEEE

Most existing distribution networks are difficult to withstand the impact of meteorological disasters. With the development of active distribution networks(ADNs), more and more upgrading and updating resources are applied to enhance the resilience of ADNs. A two-stage stochastic mixed-integer programming(SMIP) model is proposed in this paper to minimize the upgrading and operation cost of ADNs by considering random scenarios referring to different operation scenarios of ADNs caused by disastrous weather events. In the first stage, the planning decision is formulated according to the measures of hardening existing distribution lines, upgrading automatic switches, and deploying energy storage resources. The second stage is to evaluate the operation cost of ADNs by considering the cost of load shedding due to disastrous weather and optimal deployment of energy storage systems(ESSs) under normal weather condition. A novel modeling method is proposed to address the uncertainty of the operation state of distribution lines according to the canonical representation of logical constraints. The progressive hedging algorithm(PHA) is adopted to solve the SMIP model. The IEEE 33-node test system is employed to verify the feasibility and effectiveness of the proposed method. The results show that the proposed model can enhance the resilience of the ADN while ensuring economy.

关键词： Active distribution network(ADN) resilience disastrous weather event stochastic programming

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An ISAR Image Reconstruction Method via Signal Support Reweighted l1 Minimization 2

An ISAR Image Reconstruction Method via Signal Support Rewei...

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2nd IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2024

作者： Zhao, Tiehua Wu, Qihua Xu, Zhiming Ai, Xiaofeng Zhao, Feng Xiao, Shunping National University of Defense Technology The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology Changsha China

ISBN: (纸本)9798331515669

The sparse aperture caused by data loss or unintentional interference is the actual problem in radar imaging process. Therefore, a compressed sensing (CS) based ISAR image reconstruction method with signal support aided is proposed in this paper. Firstly, the signal support is constructed from FFT-based imaging results. Then the signal support is introduced as a prior information into the reweighted function during the CS reconstruction. The simulation results show that, when the azimuth effective aperture ratio is as low as 30 % and signal-to-noise ratio (SNR) equals to -10 dB, the proposed method can obtain clear imaging results like that of complete aperture data. Besides, compared with the traditional CS reconstruction method, the number of false points in the reconstruction results by proposed method is greatly reduced. © 2024 IEEE.

关键词： Radar imaging

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Dynamic Response Characteristics of Multi-Generation system Integrated with Gas and Heat Storage

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Journal of Thermal Science 2025年第3期34卷 913-935页

作者： WANG Xiaomeng DUAN Liqiang ZHENG Nan WANG Qiushi Beijing Laboratory of New Energy Storage Technology North China Electric Power University School of Energy Power and Mechanical Engineering North China Electric Power University State Key Laboratory of Alternate Electric Power System with Renewable Energy Sources (NCEPU) North China Electric Power University Institute of Technology for Carbon Neutralization College of ElectricalEnergy and Power EngineeringYangzhou University

In this paper,a new multi-generation system,incorporating solid oxide fuel cell(SOFC),gas turbine(GT),lithium bromide chiller,gas and heat storage components is proposed to address the issues of volatility in user load and energy source input and mismatching between supply and *** dynamic model and control strategy of the system are established,and the system dynamic characteristics in response to solar DNI and external load disturbances are *** system can rapidly adjust the key output and input parameters to realize a new supply-demand balance in a shorter period of time by multiple PID control *** response processes of two combined cooling,heating and power(CCHP) systems with and without gas storage to cope with load changes are *** results show that the CCHP system with gas storage can effectively shorten the response time of load *** solar collector and the SOFC-GT can reach a new equilibrium within a few tens of seconds under the *** response time of the methanol reactor is longer compared to those of solar collector and the SOFC-GT,taking several minutes to *** the cooling and heating load change,the system can adjust the output to the demand value within 500 and 260 seconds.

关键词： dynamic analysis energy storage load-following methanol to hydrogen multi-generation system

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