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Layered structural engineering of Bi 2 O 3 /PP and WO 3 /PP composites for γ-ray shielding in high energy range: anisotropic attenuation mechanisms via Monte Carlo simulation and experiments

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Journal of Materials Research and technology 2025年 36卷 10324-10336页

作者： Xiangjie Duan Jie Zhao Shuaida Song Na Zhou Jizhuang Fan Bo Tian Yunchen Du State Key Laboratory of Space Power-Sources School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 People's Republic of China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150006 People's Republic of China Heilongjiang Institute of Atomic Energy Heilongjiang Academy of Sciences Harbin 150081 People's Republic of China

The development of non-toxic and flexible polymer-based shielding composites has become a research hotspot due to the severe harm of γ ray to living organisms, mechanical equipment, and environment. However, the γ-ray shielding performance of polymer-based composites in high-energy range remains unsatisfactory. Herein, FLUKA Monte Carlo simulations capable of visualizing γ-photon transport behaviors are investigated in Bi 2 O 3 /PP and WO 3 /PP multi-layer composites with various layered configurations. The simulation results reveal significant anisotropic attenuation effects on shielding characteristics caused by layered configurations and incident path of γ-photons relative to the interface position. Subsequently, single-layer, AB, and sandwich-like ABA composites with a fixed thickness of 2.0 mm are experimentally fabricated via melt-mixing and hot press methods. At 1332 keV, sandwich-like WPPBPPWPP composite (WO 3 /PP outer layers + Bi 2 O 3 /PP core) achieves linear attenuation coefficients and radiation protection efficiency of 0.31 cm −1 and 6 %, respectively, which are 29 % higher than those of single-layer composite. These improvements originate from multiple scattering induced by interlayer interface. Additionally, layered configurations with externally placed high-density fillers (WO 3 ) and internally placed high atomic number fillers (Bi 2 O 3 ) further promote γ-photon attenuation in high-energy range. Experimental results validate the anisotropic shielding trends observed in MC simulations. Moreover, multi-layer composites demonstrate significantly improved energy storage capacity, thermal stability, and oxidation resistance while maintaining comparable to those of single-layer composites. This work provides a scalable strategy for developing non-toxic and flexible shielding materials applicable in nuclear protection, medical devices, and aerospace systems, where lightweight and efficient radiation attenuation are critical.

关键词： Polymer-based composites Multi-layer structural engineering γ-Ray shielding Monte Carlo simulation Anisotropy attenuation Heterogeneous interface

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Optimal Controller Design for Non-Affine Nonlinear Power systems with Static Var Compensators for Hybrid UAVs

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Tsinghua Science and technology 2022年第1期27卷 196-206页

作者： Yanchu Li Qingqing Ding Shufang Li Stanimir Valtchev Beijing Key Laboratory of Network System Architecture and Convergence Beijing Laboratory of Advanced Information Networkand School of Information&Communication EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua UniversityBeijing 100084China the Nova School of Science and Technology(FCT/UNL) Caparica 2829-516LisbonPortugal Technical University of Sofia(TUS) Sofia 2125Bulgaria

A generalized non-affine nonlinear power system model is presented for a single machine bus power system with a Static Var Compensator(SVC)or state Var system(SVS)for hybrid Unmanned Aerial Vehicles(UAVs).The model is constructed by differential algebraic equations on the MATLAB-Simulink platform with the programming technique of its *** the inverse system method and the Linear Quadratic Regulation(LQR),an optimized SVC controller is *** simulations under three fault conditions show that the proposed controller can effectively improve the power system transient performance.

关键词： Static Var Compensator(SVC) Unmanned Aerial Vehicles(UAV) power system non-affine nonlinear control inverse system method Linear Quadratic Regulation(LQR)

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Research on Gas Diffusion Behavior in Three-Element Mixed Insulation Oil-Paper Composite system 18th

Research on Gas Diffusion Behavior in Three-Element Mixed In...

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18th Annual Conference of China Electrotechnical Society, ACCES 2023

作者： Liu, Xiong Wang, Qian Qin, Wei Xu, Qing Zhang, Junyi Hao, Jian State Grid Chongqing Electric Power Co. Chongqing Electric Power Research Institute Chongqing404100 China State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing400044 China

ISBN: (纸本)9789819714469

The gas information in oil-immersed transformers is an important parameter in the identification of the insulation condition Three-element mixed insulation oil is a new type of insulating liquid, which has been safely used in transformer insulation systems. There is an urgent need to develop fault diagnosis method for three-element mixed insulation oil transformers. In this paper, the transfer characteristics of different types of gases between oil and paper insulation in the three-element mixed insulation oil-cellulose system are studied through simulation. The results show that when the initial position of gas is in the cellulose, the greater the absorption force between cellulose and gas, the more difficult for the gas to transfer from the cellulose to oil. When the initial position of gas is in the three-element mixed insulation oil, the larger the free volume fraction of gas molecules in oil and cellulose, the easier gas transfers from three-element mixed insulation oil to cellulose. The conclusions contribute to improving the accuracy of the fault diagnosis for three-element mixed insulation oil transformers based on dissolved gas analysis. © Beijing Paike Culture Commu. Co., Ltd. 2024.

关键词： Molecular dynamics

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Forest terrain and canopy height estimation using stereo images and spaceborne LiDAR data from GF-7 satellite

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地球空间信息科学学报（英文版） 2024年第3期27卷 811-821页

作者： Liming Du Yong Pang Wenjian Ni Xiaojun Liang Zengyuan Li Juan Suarez Wei Wei Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijingChina Key Laboratory of Forestry Remote Sensing and Information System National Forestry and Grassland AdministrationBeijingChina State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina Forest Research Northern Research StationMidlothianUK Institute of Science and Technology Information Yunnan Academy of Forestry and GrasslandKunmingChina

Accurate estimation of forest terrain and canopy height is crucial for timely understanding of forest *** Fen-7(GF-7)Satellite is China's first sub-meter-level three-dimensional(3D)mapping satellite for civilian use,which was equipped with a two-line-array stereo mapping camera and a laser altimeter system that can provide stereo images and full waveform LiDAR data *** of the existing studies have concentrated on evaluating the accu-racy of GF-7 for topographic survey in bare land,but few have in-depth studied its ability to measure forest terrain elevation and canopy *** purpose of this study is to evaluate the potential of GF-7 LiDAR and stereo image for forest terrain and height *** Airborne Laser Scanning(ALS)data were utilized to generate reference terrain and forest vertical *** validation test was conducted in Pu'er City,Yunnan Province of China,and encouraging results have *** GF-7 LiDAR data obtained the accuracy of forest terrain elevation with RMSE of 8.01 m when 21 available laser footprints were used for results verification;meanwhile,when it was used to calculate the forest height,R2 of 0.84 and RMSE of 3.2 m were obtained although only seven effective footprints were used for result *** canopy height values obtained from GF-7 stereo images have also been proven to have high accuracy with the resolution of 20 m x 20 m compared with ALS data(R2=0.88,RMSE=2.98 m).When the results were verified at the forest sub-compartment scale that taking into account the forest types,further higher accuracy(R2=0.96,RMSE=1.23 m)was *** results show that GF-7 has considerable application potential in forest resources monitoring.

关键词： Gao Fen-7(GF-7) spaceborne LiDAR stereo image Airborne Laser Scanning(ALS) forest height Pu'er

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Air-Ground Collaborative Mobile Edge Computing:Architecture,Challenges,and Opportunities

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China Communications 2024年第5期21卷 1-16页

作者： Qin Zhen He Shoushuai Wang Hai Qu Yuben Dai Haipeng Xiong Fei Wei Zhenhua Li Hailong College of Communications Engineering Army Engineering University of PLANanjing 210000China Department of Information and Communication Noncommissioned Officer Academy of PAPHangzhou 310000China Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Ministry of Industry and Information TechnologyNanjing 211106China College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China State Key Laboratory for Novel Software Technology Nanjing UniversityNanjing 210023China CMC Political and Law Commission Beijing100120China Xi’an Research Institute of High Technology Xi’an 710025China

By pushing computation,cache,and network control to the edge,mobile edge computing(MEC)is expected to play a leading role in fifth generation(5G)and future sixth generation(6G).Nevertheless,facing ubiquitous fast-growing computational demands,it is impossible for a single MEC paradigm to effectively support high-quality intelligent services at end user equipments(UEs).To address this issue,we propose an air-ground collaborative MEC(AGCMEC)architecture in this *** proposed AGCMEC integrates all potentially available MEC servers within air and ground in the envisioned 6G,by a variety of collaborative ways to provide computation services at their best for ***,we introduce the AGC-MEC architecture and elaborate three typical use ***,we discuss four main challenges in the AGC-MEC as well as their potential ***,we conduct a case study of collaborative service placement for AGC-MEC to validate the effectiveness of the proposed collaborative service placement ***,we highlight several potential research directions of the AGC-MEC.

关键词： air-ground architecture collaborative mobile edge computing

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Formation of secondary inorganic aerosol in a frigid urban atmosphere

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Frontiers of Environmental Science & Engineering 2022年第2期16卷 39-50页

作者： Yuan Cheng Qinqin Yu Jiumeng Liu Youwen Sun Linlin Liang Zhenyu Du Guannan Geng Wanli Ma Hong Qi Qiang Zhang Kebin He State Key Laboratory of Urban Water Resource and Environment School of EnvironmentHarbin Institute of TechnologyHarbin 150090China Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China State Key Laboratory of Severe Weather&CMA Key Laboratory of Atmospheric Chemistry Chinese Academy of Meteorological SciencesBeijing 100081China National Research Center for Environmental Analysis and Measurement Environmental Development Center of the Ministry of Ecology and EnvironmentBeijing 100029China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Department of Earth System Science Tsinghua UniversityBeijing 100084China

Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,*** sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement *** to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less *** addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~***,the sulfate formation was considered inefficient in this *** excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being *** nitrate to sulfate ratio tended to increase with increasing temperature as *** on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also *** stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely *** different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.

关键词： Haze Sulfate Nitrate Heterogeneous chemistry Biomass burning

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Multi Physical Modeling for the Press-Pack IGBT Device by Considering Material Temperature Effect 3

Multi Physical Modeling for the Press-Pack IGBT Device by Co...

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3rd IEEE International Power Electronics and Application Conference and Exposition, PEAC 2022

作者： Yao, Ran Li, Hui Duan, Zeyu Lai, Wei Chen, Zhongyuan Li, Yaosheng Chongqing University State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing China Beijing Institute of Smart Energy State Key Laboratory of Advanced Power Transmission Technology Beijing China

ISBN: (数字)9781665491419

ISBN: (纸本)9781665491419

The accuracy of multi-physics simulation analysis of Press-Pack IGBT (PP-IGBT) devices is related to the failure simulation and reliability lifetime modeling. The existing finite element modeling of PP-IGBT devices only considers the coupling relationship between various physical fields. The temperature effects on the material properties are ignored, which may lead to errors in the stress evaluation of the PP-IGBT device between finite element simulation and actual operation. This paper proposes a multi-physics coupling finite element modeling method for the PP-IGBT device by considering the temperature effect of materials. Firstly, the thermal conductivity and electrical conductivity of the packaging material in the PP-IGBT device are analyzed, and a finite element calculation method that considers the temperature effects of material properties is proposed. Secondly, the electrical, thermal, and mechanical coupling finite element model of the PP-IGBT device is established with temperature feedback. The performance of the PP-IGBT device is compared to the existing and proposed multi-physics coupling finite element model under power cycling conditions. Finally, the infrared temperature test platform of the PP-IGBT device is established to verify the effectiveness of the proposed finite element model. The results show that compared to the existing finite element model of the PP-IGBT device, the average errors of the proposed model are reduced by about 5 %. © 2022 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

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Human-Robot Collaborative Decision Method of Hexapod Robot Based on Prior Knowledge and Negotiation Strategy

SSRN

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SSRN 2024年

作者： You, Bo Chen, Xiaolei Li, Jiayu Ding, Liang Dong, Zheng The Key Laboratory of Intelligent Technology for Cutting and Manufacturing Ministry of Education Harbin University of Science and Technology Harbin150080 China The Heilongjiang Provincial Key Laboratory of Complex Intelligent System and Integration Harbin University of Science and Technology Harbin150080 China The Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

Against the unstructured terrain environment, human drivers often rely on remote operating patterns to accomplish tasks with robots. With the gradual improvement in robot intelligence, a key problem that urgently requires attention is how to bridge cognitive and perceptual differences between human and robot in collaborative decision-making processes. Particularly effective resolution of differences in decision outcomes is crucial. Therefore, this paper utilizes the decision logic process and prior knowledge model of human drivers to form robot’s decision framework, narrowing the cognitive differences between human and robot. Besides, embedding the human-robot-environment features that affect the decision-making process as prior knowledge into the robot’s decision-making system can effectively reduce perceptual gaps. Under the same decision framework, a negotiation strategy is proposed for forming a unified decision outcome between human and robot by finding an optimal concession rate. This study utilizes a hexapod robot simulated driving platform to gather experimental data and develop prior knowledge for robots. It also leverages virtual reality equipment and visual augmentation technologies to establish a remote human-robot collaborative decision-making experimental system. The experimental results conducted in complex obstacle terrain demonstrate the effectiveness of adopting the negotiation strategy for human-robot collaborative decision-making. Compared with the individual human or robot decision, the human-robot collaborative decision method significantly enhances robot stability, reduces energy consumption, and minimizes collisions. © 2024, The Authors. All rights reserved.

关键词： Decision making

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A Novel Post-Transient Voltage-Based Protection Scheme for DC Shipboard systems

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IEEE Transactions on Transportation Electrification 2025年第3期11卷 8377-8389页

作者： Wang, Dong Hu, Pengfei Cao, Yu Syed, Mazheruddin Zhejiang University Zhejiang Key Laboratory of Electrical Technology and System on Renewable Energy College of Electrical Engineering Hangzhou310027 China State Grid Zhejiang Electric Power Company Ltd. Hangzhou Power Supply Company Hangzhou310050 China WSP GlasgowG1 3BX United Kingdom

With increasing environmental concerns in transportation, existing shipboard power distribution systems are under pressure regarding system efficiency and fuel consumption constraints. DC shipboard systems are being considered as an effective solution to alleviate these pressures, offering convenient connections of variable speed engines, energy storages, and shaft generators. However, the development of fast, selective, and reliable protection solutions remains a key challenge, critical for the broader adoption of dc shipboard systems. Compared to existing HVdc grids and transmission systems, dc shipboards are more compact, leading to rapid propagation of fault disturbances. This necessitates more stringent protection coordination and selectivity requirements. This article develops a novel post-transient voltage (PTV)-based protection scheme. The method utilizes inherent PTV features to distinguish downstream and upstream internal and external faults. The proposed method provides anti-noise capabilities, overcoming selectivity limitations of existing voltage-based solutions when a lower sampling frequency is applied. The credibility and the effectiveness of the proposed scheme are tested against different fault scenarios applied on a dc shipboard test system built in power systems computer aided design (PSCAD)/electromagnetic transients including direct current (EMTdc) and validated in a real time (RT)-Box-based hardware testbed. Noise signals are considered in the tests to appraise the resilience of the developed protection scheme. © 2015 IEEE.

关键词： HVDC power transmission

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Study on Thermal Aging Insulation Characteristics of Transformer Oil-Paper Insulation 4

Study on Thermal Aging Insulation Characteristics of Transfo...

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4th IEEE International Conference on Power, Electronics and Computer Applications, ICPECA 2024

作者： Qin, Chunxu Lin, Wenjie Huang, Yongxiang Liang, Huijuan Hua, Huichun College of Electric Power Inner Mongolia University of Technology Hohhot China North China Electric Power University State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources Baoding China

ISBN: (纸本)9798350359589

The insulation aging of rectifier transformers is one of the significant factors affecting the stable operation of the power grid. To clarify the aging mechanism of transformer oil-paper insulation, establish measures for aging prevention and deceleration, and enhance the reliability of electrical equipment operation, this study summarizes the characteristics and variations of recent thermal aging products of oil-paper insulation. It emphasizes the influence of moisture on transformer oil-paper insulation and summarizes the electrical characteristics of transformer thermal aging. This research provides technical insights for the long-term stable operation of transformer oil-paper insulation equipment. © 2024 IEEE.

关键词： Breakdown voltage Insulation characteristics Oil-paper insulation Thermal aging

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