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Cavitation research with computational fluid dynamics:From Euler-Euler to Euler-Lagrange approach

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Journal of Hydrodynamics 2024年第1期36卷 1-23页

作者： Bin Ji Zi-yang Wang Huai-yu Cheng Rickard E.Bensow State Key Laboratory of Water Resources Engineering and management Wuhan UniversityWuhan430072China department of Mechanics and maritime Sciences Chalmers University of TechnologyGothenburgSweden

Unsteady cavitating flow often contains vapor structures with a wide range of different length scales,from micro-bubbles to large cavities,which issues a big challenge to precisely investigate its evolution mechanism by computational fluid dynamics(CFD)*** present work reviews the development of simulation methods for cavitation,especially the emerging Euler-Lagrange ***,the progress of the numerical investigation of hot and vital issues is discussed,including cavitation inception,cloud cavitation inner structure and its formation mechanism,cavitation erosion,and cavitation *** is indicated that the Euler-Lagrange method can determine cavitation inception point *** cloud cavitation,the Euler-Lagrange method can reveal the source of microbubbles and their distribution law inside the shedding *** method also has advantages and great potential in assessing cloud cavitation-induced erosion and *** the ever-growing demands of cavitation simulation accuracy in basic research and engineering applications,how to improve the Euler-Lagrange method’s stability and applicability is still an open *** further promote the application of this advanced CFD simulation technology in cavitation research,some key issues are to be solved and feasible suggestions are put forward for further work.

关键词： numerical simulation Euler-Euler method Euler-Lagrange method bubble dynamicsgy,Gothenburg,Sweden

Experimental study on the dynamic response of a 3-D wedge under asymmetric impact

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Journal of Hydrodynamics 2024年第2期36卷 263-274页

作者： Saeed Hosseinzadeh Kristjan Tabri maritime Engineering Research Group School of EngineeringUniversity of SouthamptonSouthamptonUK department of Civil Engineering and Architecture Tallinn University of TechnologyTallinnEstonia Marine technology Competence Center Tallinn University of TechnologyKuressaareEstonia

Water entry problems represent complex multiphase flows involving air,water,and structure interaction,occurring rapidly in rough seas,and potentially effecting structural integrity of floating *** paper experimentally investigates asymmetric slamming loads acting on a 3-D elastic wedge *** specimen,featuring two different bottom plates(stiffened and unstiffened),each 4 mm thick,aims to assess the effect of structural stiffness on dynamic *** experiments are conducted at different drop heights of 25 cm and 50 cm and varying heel angles from 5°to 25°.The paper describes the experimental conditions,including wedge geometry,material properties,and the test *** study explores the influence of heel angle on impact acceleration,revealing an increase in peak acceleration with a higher inclination angle,particularly in the vertical ***,the hydrodynamic pressure resulting from asymmetric slamming is *** pressure results analyzed and compared at different locations along the length of the *** experimental findings indicate that,despite the leeward side(stiffened)experiencing a smaller hydrodynamic load,the heel angle significantly affects pressure results on the windward side(unstiffened),leading to a more pronounced dynamic *** time history of pressure results emphasizes the effect of elastic vibrations,particularly noticeable on the unstiffened bottom *** study contributes to a deeper understanding of asymmetric slamming on aluminum structures,facilitating the enhancement of mathematical models and the validation of numerical simulations.

关键词： Flexible fluid structure interactions(FFSI) experimental study asymmetric impact hydrodynamic pressure slamming loads

Models to Simulate Effective Coverage of Fire Station Based on Real-Time Travel Times

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 483-513页

作者： Sicheng Zhu Dingli Liu Weijun Liu Ying Li Tian Zhou department of Engineering management Changsha University of Science and TechnologyChangsha410114China

In recent years,frequent fire disasters have led to enormous damage in *** firefighting rescues can minimize the losses caused by *** the rescue processes,the travel time of fire trucks can be severely affected by traffic conditions,changing the effective coverage of fire ***,it is still challenging to determine the effective coverage of fire stations considering dynamic traffic *** paper addresses this issue by combining the traveling time calculationmodelwith the effective coverage *** addition,it proposes a new index of total effective coverage area(TECA)based on the time-weighted average of the effective coverage area(ECA)to evaluate the urban fire *** also selects China as the case study to validate the feasibility of the models,a fire station(FS-JX)in ***-JX station and its surrounding 9,117 fire risk points are selected as the fire service supply and demand points,respectively.A total of 196 simulation scenarios throughout a consecutiveweek are ***,1,933,815 sets of valid sample data are *** results showed that the TECA of FS-JX is 3.27 km^(2),which is far below the standard requirement of 7.00 km^(2) due to the traffic *** visualization results showed that three rivers around FS-JX interrupt the continuity of its effective *** proposed method can provide data support to optimize the locations of fire stations by accurately and dynamically determining the effective coverage of fire stations.

关键词： Fire services fire station effective coverage real-time traffic simulation

An effective strategy for dendrite free Li metal anodes:Nickel foam decorated with high lattice-matching CoN and CoF_(2) nanosheets for dense deposition

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Nano Research 2024年第5期17卷 4069-4078页

作者： Wenlong Liu Jianzong Man Xiaodong Sun Ning Zhang Yehong Du Kun Liu Zhongsheng Wen Song Li Juncai Sun Institute of Materials and technology Dalian Maritime UniversityDalian 116026China Shandong Provinvial Key Laboratory of Chemical Energy Storage and Novel Cell technology and School of Chemistry and Chemical enginneringLiaocheng UniversityLiaocheng 252000China department of Public Security management Liaoning Police CollegeDalian 116036China

The notorious dendrite and infinite volume change seriously restrict the advancement of lithium metal anodes(LMAs),during the long-term process of stripping/***,the nanosheets of metal fluoride(CoF_(2))and metal nitride(CoN)with magnificent lithiophilicity on the nickel(Ni)foam are designed as the“regulator”to uniform the Li plating and build stronger solid electrolyte interface(SEI)layer for dendrite free *** Ni foam offers abundant space to receive deposited Li *** CoN nanosheets can guarantee the fast transfer of electrons,which provides a stable interface of Li^(+)***,the nanosheet structure with lithiophilicity would accelerate the move of Li+and decrease the nucleation barrier,due to the high lattice-matching of Li and ***,the CoF_(2) could increase the content of F(LiF)in the SEI layer,which enhances the strength and avoids the destruction of SEI *** the cooperation of CoN and CoF_(2),the composited anode(Li/NF@CNCF)exhibits ultra-long cycle performance(more than 1200 h)and fantastic structure stability at 1 mA·cm^(-2) with 1 mAh·cm^(-2).Based on the LiFePO_(4) and Li/NF@CNCF,the full cells deliver excellent specifical capacity and steady coulombic *** strategy contributes an effective approach to alleviate the issues of lithium metal anodes in the field of LMAs.

关键词： CoN and CoF_(2) lattice-matching nanosheet lithiophilicity lithium metal anodes

RepDNet:A re-parameterization despeckling network for autonomous underwater side-scan sonar imaging with prior-knowledge customized convolution

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Defence technology（防务技术） 2024年第5期35卷 259-274页

作者： Zhuoyi Li Zhisen Wang Deshan Chen Tsz Leung Yip Angelo P.Teixeira department of Logistics and maritime Studies The Hong Kong Polytechnic UniversityChina State Key Laboratory of maritime technology and Safety Wuhan University of TechnologyChina School of Transportation and Logistics Engineering Wuhan University of TechnologyChina National Engineering Research Center for Water Transport Safety Wuhan University of TechnologyChina Centre for Marine technology and Ocean Engineering(CENTEC) Instituto Superior TecnicoUniversidade de LisboaPortugal

Side-scan sonar(SSS)is now a prevalent instrument for large-scale seafloor topography measurements,deployable on an autonomous underwater vehicle(AUV)to execute fully automated underwater acoustic scanning imaging along a predetermined ***,SSS images often suffer from speckle noise caused by mutual interference between echoes,and limited AUV computational resources further hinder noise *** approaches for SSS image processing and speckle noise reduction rely heavily on complex network structures and fail to combine the benefits of deep learning and domain *** address the problem,Rep DNet,a novel and effective despeckling convolutional neural network is *** DNet introduces two re-parameterized blocks:the Pixel Smoothing Block(PSB)and Edge Enhancement Block(EEB),preserving edge information while attenuating speckle *** training,PSB and EEB manifest as double-layered multi-branch structures,integrating first-order and secondorder derivatives and smoothing *** inference,the branches are re-parameterized into a 3×3 convolution,enabling efficient inference without sacrificing *** DNet comprises three computational operations:3×3 convolution,element-wise summation and Rectified Linear Unit *** on benchmark datasets,a real SSS dataset and Data collected at Lake Mulan aestablish Rep DNet as a well-balanced network,meeting the AUV computational constraints in terms of performance and latency.

关键词： Side-scan sonar Sonar image despeckling Domain knowledge Re-parameterization

Influence of railway wheel tread damage on wheel-rail impact loads and the durability of wheelsets

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Railway Engineering Science 2024年第1期32卷 20-35页

作者： Michele Maglio Tore Vernersson Jens C.O.Nielsen Anders Ekberg Elena Kabo CHARMEC Department of Mechanical and Maritime SciencesChalmers University of TechnologySE‑41296 GothenburgSweden

Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle *** on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation *** relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is *** calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are *** results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.

关键词： Wheel tread damage Rolling contact fatigue cluster Field measurements Dynamic vehicle-track interaction Wheel-rail impact load Wheelset durability

Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 562-573页

作者： Huimin Zhao Zhikang Shuai Jun Ge An Luo Weimin Wu Z.John Shen College of Electrical and Information Engineering Hunan UniversityChangsha 410006China Electrical Engineering department Shanghai Maritime UniversityShanghai 201306China department of Electrical and Computer Engineering Ilinois Institute of TechnologyChicagoIL 60616 USA

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyzing the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyzed. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyzed. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

关键词： Asymmetrical fault analysis droop control fault current calculation method limiter transient fault characteristics

Coupling and coordinated evolution characteristics of regional economy-energy-carbon emission multiple systems:A case study of main China's Basin

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Journal of Environmental Sciences 2024年第6期140卷 204-218页

作者： Lu Chen Xin Li Jingyi Zhao Xinyu Kang Lu Liu Minxi Wang Wu Chen College of management Science Chengdu University of TechnologyChengdu 610051China SDU Life Cycle Engineering Department of Green TechnologyUniversity of Southern Denmark5230 OdenseDenmark

Comprehensive analysis of the Economy-Energy-Carbon Emission(EECE)system is beneficial for promoting sustainable social *** study analyzes the system development of major watersheds in China from 2010 to *** research fully considers the system’s internal and external inputs and outputs and proposes an evaluation index system for regional EECE coupling and coordinated ***,using the difference in system weight allocation to improve the coupling and coordination model,the study explores the dynamic system’s coupling and *** results show that(1)The development of the system structure is relatively stable,but the overall development status is not ideal;(2)The downstream of China’s main river basins has obvious economic advantages,while the energy system fluctuates *** efficiency of the carbon emission system will decrease in areas with rapid economic *** coupling and coordination level of the EECE system is better in the Yangtze River Basin than in the Yellow River Basin;(3)From the perspective of dynamic coordinated development,the main river basins have been divided into two states since 2012,but it is relatively stable *** dynamic coordination is often at a disadvantage in regions with rapid economic and energy development;(4)The coupling coordination degree of the two river basins has significant positive spatial *** provinces’significant spatial clustering characteristics of the coupling coordination degree are High-High ***-Low type provinces are mainly concentrated *** research process has certain reference significance for the collaborative governance of complex regional systems.

关键词： System structure Efficiency measure Coupling mechanism Dynamic coordination

A Multi-Objective Optimization for Locating Maintenance Stations and Operator Dispatching of Corrective Maintenance

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Computers, Materials & Continua 2024年第6期79卷 3519-3547页

作者： Chao-Lung Yang Melkamu Mengistnew Teshome Yu-Zhen Yeh Tamrat Yifter Meles department of Industrial management National Taiwan University of Science and TechnologyTaipie106Taiwan department of Industrial Engineering University of Gondar Institute of TechnologyGondar196Ethiopia

In this study,we introduce a novel multi-objective optimization model tailored for modern manufacturing,aiming to mitigate the cost impacts of operational disruptions through optimized corrective *** to our approach is the strategic placement of maintenance stations and the efficient allocation of personnel,addressing a crucial gap in the integration of maintenance personnel dispatching and station *** model uniquely combines the spatial distribution of machinery with the expertise of operators to achieve a harmonious balance between maintenance efficiency and *** core of our methodology is the NSGA Ⅲ+Dispatch,an advanced adaptation of the Non-Dominated Sorting Genetic Algorithm Ⅲ(NSGA-Ⅲ),meticulously designed for the selection of maintenance stations and effective operator *** method integrates a comprehensive coding process,crossover operator,and mutation operator to efficiently manage multiple *** empirical testing,including a detailed analysis from a taiwan region electronic equipment manufacturer,validated the effectiveness of our approach across various scenarios of machine failure frequencies and operator *** findings reveal that the proposed model significantly outperforms current practices by reducing response times by up to 23%in low-frequency and 28.23%in high-frequency machine failure scenarios,leading to notable improvements in efficiency and cost ***,it demonstrates significant improvements in oper-ational efficiency,particularly in selective high-frequency failure contexts,while ensuring substantial manpower cost savings without compromising on operational *** research significantly advances maintenance strategies in production environments,providing the manufacturing industry with practical,optimized solutions for diverse machine malfunction ***,the methodologies and principles developed in this study have pote

关键词： Corrective maintenance multi-objective optimization non-dominated sorting genetic algorithmⅢ operator allocation maintenance station location