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Numerical Prediction of Ride Comfort of Tracked Vehicle Equipped with Novel Flexible Road Wheels

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Chinese Journal of Mechanical eng.neering 2024年第4期 290-302页

作者： Yaoji Deng.Zhiyue Wang Youqun Zhao Junjie Gong Hui Shen Fen Lin college of Mechanical eng.neering Yangzhou University college of Energy and power eng.neering Nanjing University of Aeronautics and Astronautics

Enhancing ride comfort has always constituted a crucial focus in the design and research of modern tracked vehicles, heavily reliant on the driving system's performance. While the road wheel is a key component of the driving system, traditional road wheels predominantly adopt a solid structure, exhibiting subpar adhesion performance and damping effects, thereby falling short of meeting the demands for high-speed, stable, and long-distance driving in tracked vehicles. Addressing this issue, this paper proposes a novel type of flexible road wheel(FRW) characterized by a catenary construction. The study investigates the ride comfort of tracked vehicles equipped with flexible road wheels by integrating finite element and vehicle dynamic. First, three-dimensional(3D) finite element(FE) models of both flexible and rigid road wheels are established, considering material and contact nonlinearities. These models are validated through a wheel radial loading test. Based on the validated FE model, the paper uncovers the relationship between load and radial deformation of the road wheel, forming the basis for a nonlinear mathematical ***, a half-car model of a tracked vehicle with seven degrees of freedom is established using Newton's second law. A random road model, considering the track effect and employing white noise, is constructed. The study concludes by examining the ride comfort of tracked vehicles equipped with flexible and rigid road wheels under various speeds and road grades. The results demonstrate that, in comparison to the rigid road wheel(RRW), the flexible road wheel enhances the ride comfort of tracked vehicles on randomly uneven roads. This research provides a theoretical foundation for the implementation of flexible road wheels in tracked vehicles.

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Automatic Generation Control in a Distributed power Grid Based on Multi-step Reinforcement Learning

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Protection and Control of Modern power Systems 2024年第4期9卷 39-50页

作者： Wenmeng.Zhao Tuo Zeng.Zhihong Liu Lihui Xie Lei Xi Hui Ma the Electric power Research Institute Southern Power GridGuangzhou 510663China the Heyuan power Supply Bureau Guang-dong Power Grid Co.Ltd.Heyuan 517000China the college of Electrical eng.neering&New Energy China Three Gorges UniversityYichang 443002China the college of Electrical eng.neering&New Energy and Hubei Provincial Key Laboratory for Operation and Control of Cascaded Hydropower Station China Three Gorges UniversityYichang 443002China IEEE

The increasing use of renewable energy in the power system results in strong stochastic disturbances and degrades the control performance of the distributed power *** this paper,a novel multi-agent collaborative reinforcement learning algorithm is proposed with automatic optimization,namely,Dyna-DQL,to quickly achieve an optimal coordination solution for the multi-area distributed power *** proposed Dyna framework is combined with double Q-learning to collect and store the environmental *** can iteratively update the agents through buffer replay and real-time *** the environmental data can be fully used to enhance the learning speed of the *** mitigates the negative impact of heavy stochastic disturbances caused by the integration of renewable energy on the control *** are conducted on two different models to validate the effectiveness of the proposed *** results demonstrate that the proposed Dyna-DQL algorithm exhibits superior stability and robustness compared to other reinforcement learning algorithms.

关键词： Automatic generation control Dyna framework distributed power grid multi-agent mod-el-based reinforcement learning

Modeling the System for Hybrid Renewable Energy Using Highly Efficient Converters and Generator

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CES Transactions on Electrical Machines and Systems 2024年第3期 356-366页

作者： Tefera Kitaba Department of Electrical power eng.neering Ethiopian Defence University College of Engineering

High-efficient isolated DC/DC converters with a high-efficiency synchronous reluctance generator(SRG) are the ultimate solutions in DC microgrid systems. The design and modeling of isolated DC/DC converters with the performance of SRG are carried out. On the generator side, reactive and active powers are used as pulse width modulation(PWM) control variables. Further, the flux estimator is used. Three-phase PWM rectifier is used by applying space vector modulation(SVM) with a constant switching frequency for direct power control. Further, the paper also includes the experimental validation of the results. The paper also proposes that highly efficient power converters and synchronous reluctance generators are required to achieve high performance for hybrid renewable energy systems applications.

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Flame Structure of Methane and Kerosene Combustion with a Compact Concave Flame-Holder using the LES-pdf Method

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Journal of Thermal Science 2024年第1期33卷 222-234页

作者： WANG Fang WANG Yunfan WEI Guanyi LIU Deng.uan JIN Jie JONES P.William School of Energy and power eng.neering Beihang UniversityBeijingBeijing 100191China Department of Mechanical eng.neering Imperial College LondonLondon SW72AZUK

Compact flame-holders for afterburners are an increasing requirement for modern aero ***,flame-holder design is non-trivial since high inlet temperatures,velocities,and elaborate structures induce complex turbulence,combustion,and spray coupling in modern *** this work,the LES-pdf and stochastic fields-Lagrangian particle spray methods are used to investigate methane and aviation kerosene combustion structures formed by new-type concave *** flow pattern,combustion mode,and flame structure of gaseous and liquid fuel around a concave flame-holder are analyzed,discussed,and compared with experimental *** reveal that the flame stability of a concave flame-holder is better than that of the non-concave ***,when using liquid fuel,the concave flame-holder forms a stable and compact *** results suggest concave flame-holders are a promising design for compact afterburners.

关键词： concave structure flame-holder LES-pdf spray combustion flame structure AECSC

Electrical discharge and arc milling with automatic tracking of optimal flushing direction:A novel high-efficiency compound machining method

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Chinese Journal of Aeronautics 2024年第3期37卷 351-364页

作者： Xinlei WU Yonghong LIU Peng.in ZHANG Liang QI Dege LI Chi MA Renjie JI college of Mechanical and Electronic eng.neering China University of Petroleum(East China)Qingdao 266580China School of Mechanical and power eng.neering Nanjing Tech UniversityNanjing 211816China

The arc milling method has the advantages of high machining efficiency and low cost and is independent of the streng.h and hardness of machined ***,frequent electrode back-offs and the risk of workpiece burning may occur if erosion products are not removed *** this study,it was found that the flushing method of the working medium had a significant impact on the machining performance of arc *** on this,a novel highefficiency compound machining method of electrical discharge and arc milling with automatic tracking of the optimal flushing direction was *** automatic tracking optimizer for external working medium injection was designed to determine the optimal external flushing direction according to the feed *** influence of flushing methods,working mediums,and machining parameters on the machining efficiency,tool electrode wear rate,machining error,and surface integrity of titanium alloys were *** results indicated that better machining performance and environmental friendliness were achieved using the compound flushing method of outer compressed air and inner deionized ***,the automatic tracking flushing method in the opposite direction of the feed direction showed superior results compared to other *** material removal rate with the opposite direction injection could be increased up to 1.62 times that of the same direction,and the relative electrode wear rate could be reduced by 14.76%.This novel method has broad application prospects for machining parts with difficult-to-cut materials in aerospace and military industries.

关键词： Arc milling Dielectric Difficult-to-cut materials Electric discharge machining Erosion Material removal rate

Using CONTAM to design ventilation strategy of negative pressure isolation ward considering different height of door gaps

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Energy and Built Environment 2024年第1期5卷 32-45页

作者： Mingyao Ma Changsheng.Cao Yukun Xu Zhijian Liu Lingjie Zeng.Cheng.uan Zhang Jun Gao School of Mechanical eng.neering Tongji UniversityShanghai 200092China Department of power eng.neering North China Electric Power UniversityBaodingHebei 071003China college of Civil eng.neering Tongji UniversityShanghai 200092China

Infectious disease departments in hospitals require pressure gradient to create unidirectional airflow to prevent the spread of contaminants,typically by creating active air infiltration through the difference between supply and exhaust air *** door gap is the channel of air flow between rooms,so its height has an important influence on the pressure difference and infiltration air volume of the *** is still a lack of research on setting reasonable ventilation strategies according to the different heights of door gaps at different positions in the *** this study,model of a set of isolation wards was established and analyzed using the multi-zone simulation software CONTAM,and the ventilation strategies with different heights of door gaps were applied to the actual infection diseases *** results show that in a building with ventilation system divided by functional area,the difference in the height of the door gaps requires different active infiltration air *** fluctuations in the medical and patient corridors are greater than in other *** significance of this study is to understand the active infiltration of air to guide the design and operation of ventilation systems in infectious disease hospitals or building remodeled to isolate close contacts of COVID-19 *** is also instructive for the design of pressure gradients in clean workshops,biological laboratories,and other similar buildings.

关键词： Door gap height Active infiltration Pressure gradient Multizone model CONTAM Control strategy

Insight study of rare earth elements in PM_(2.5)during five years in a Chinese inland city:Composition

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Journal of Environmental Sciences 2024年第4期138卷 439-449页

作者： Yi-Wen Shen Chang-Xian Zhao Hao Zhao Shuo-Fei Dong Qi Guo Jiao-Jiao Xie Mei-Ling Lv Chun-Gang Yuan Hebei Key Lab of power Plant Flue Gas Multi-Pollutants Control Department ofEnvironmental Science&EngineeringNorth China Electric Power UniversityBaoding 071000China MOE Key Laboratory of Resources and Environmental Systems Optimization College of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China Agilent Technologies Co.Ltd.(China) Beijing 100102China

The booming development of rare earth industry and the extensive utilization of its products accompanied by urban development have led to the accelerated accumulation of rare earth elements(REEs)as emerging pollutants in atmospheric *** this study,the variation of REEs in PM_(2.5)with urban(a non-mining city)transformation was investigated through five consecutive years of sample *** compositional variability and provenance contribution of REEs in PM_(2.5)were characterized,and the REEs exposure risks of children and adults via inhalation,ingestion and dermal absorption were also *** results showed an increase in the total REEs concentration from 46.46±35.16 mg/kg(2017)to 81.22±38.98 mg/kg(2021)over the five-year period,with Ce and La making the largest *** actual increment of industrial and traffic emission source among the three pollution sources was 1.34 ng/m^(3).Coal combustion source displayed a downward *** was the main exposure pathway for REEs in PM_(2.5)for both children and *** contributed the most to the total intake of REEs in PM_(2.5)among the population,followed by La and *** exposure risks of REEs in PM_(2.5)in the region were relatively low,but the trend of change was of great *** was strongly recommended to streng.hen the concern about traffic-related non-exhaust emissions of particulate matter.

关键词： Rare earth elements Exposure risks Pollution sources Traffic-related non-exhaust emissions

Optimal Planning of Hybrid AC/DC Low-voltage Distribution Networks Considering DC Conversion of Three-phase Four-wire Low-voltage AC Systems

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Journal of Modern power Systems and Clean Energy 2024年第1期12卷 141-153页

作者： Bo Zhang Lu Zhang Wei Tang Gen Li Chen Wang the college of Information and Electrical eng.neering China Agricultural UniversityBeijing 100083China the Electric Energy Group Department of Engineering TechnologyTechnical University of Denmark(DTU)2750 BallerupDenmark the power Distribution Technology Center State Grid Beijing Electric Power Research InstituteBeijing 100075China

The increasing integration of distributed household photovoltaics(PVs)and electric vehicles(EVs)may further ag gravate voltage violations and unbalance of low-voltage distribu tion networks(LVDNs).DC distribution networks can increase the accommodation of PVs and EVs and mitigate mutilple pow er quality problems by the flexible power regulation capability of voltage source *** paper proposes schemes to es tablish hybrid AC/DC LVDNs considering the conversion of the existing three-phase four-wire low-voltage AC systems to DC op *** characteristics and DC conversion constraints of typical LVDNs are *** addition,converter configura tions for typical LVDNs are proposed based on the three-phase four-wire characteristics and quantitative analysis of various DC ***,an optimal planning method of hybrid AC/DC LVDNs is proposed,which is modeled as a bi-level programming model considering the annual investments and three-phase *** are conducted to verify the effectiveness of the proposed optimal planning *** ulation results show that the proposed optimal planning method can increase the integration of PVs while simultaneously reduc ing issues related to voltage violation and unbalance.

关键词： Optimal planning low-voltage distribution net work three-phase unbalance DC conversion

Morphological analysis for thermodynamics of cavitation collapse near fractal solid wall

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Chinese Physics B 2024年第6期33卷 422-432页

作者：单鸣雷杨雨阚雪芬殷澄韩庆邦 Jiangsu Key Laboratory of power Transmission and Distribution Equipment Technology Hohai UniversityChangzhou 213022China college of Information Science and Technology Nanjing Forestry UniversityNanjing 210000China Department of Transportation eng.neering Jiangsu Shipping CollegeNantong 226000China

A fractal geometric boundary with natural wall features is introduced into a hybrid lattice-Boltzmann-method(LBM)multiphase model. The physical model of cavitation bubble collapse near the irregular geometric wall is established to study the thermodynamic characteristics of the bubble collapse. Due to the lack of periodicity, symmetry, spatial uniformity and obvious correlation in the LBM simulation of the bubble collapse near the fractal wall, the morphological analysis based on Minkowski functional is introduced into the thermodynamic investigation of cavitation bubble so as to analyze and obtain the effective information. The results show that the Minkowski functional method can employed to study the temperature information in complex physical fields hierarchically and quantitatively. The high/low temperature region of the cavitation flow is explored, and thermal effect between irregular and fractal geometric wall and cavitation bubble can be revealed. It illustrates that LBM and morphological analysis complement each other, and morphological analysis can also be used as an optional and potential tool in research field of complex multiphase flows.

关键词： lattice Boltzmann method cavitation bubble morphological analysis