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Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 213-227页

作者： Changhui Liu Jing Wang Ying Zheng Ke Jin Jianbo Yu Jianfeng Liu School of Mechanical Engineering Tongji UniversityShanghai 201804China shanghai Jiaotong University Shanghai 200240China shanghai Waigaoqiao Shipbuilding co. Ltd.Shanghai 200137China

There are lots of researches on fixture layout optimization for large thin-walled *** researches focus on the positioning problem,i.e.,optimizing the positions of a co.stant number of ***,how to determine the number of fixtures is *** most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra ***,this paper co.structs an optimization model to minimize the number of *** co.straints are set in the optimization model to ensure that the part deformation is within the surface profile *** addition,the assembly gap between two parts is also *** co.duct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia *** the algorithm,particles are enco.ed acco.ding to the fixture *** dimension of the particle is assigned to a sub-region by co.straining the optional position range of each fixture to improve the optimization ***,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality *** research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation co.trol at the same time.

关键词： Assembly quality Large thin-walled parts Fixture layout PSO FEM

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 15-39页

作者： Changhui Liu Jing Wang Binghai Zhou Jianbo Yu Ying Zheng Jianfeng Liu School of Mechanical Engineering Tongji UniversityShanghai 201804China shanghai Jiaotong University Shanghai 200240China shanghai Waigaoqiao Shipbuilding co. Ltd.Shanghai 200137China

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past ***,few papers systematically review these *** analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods *** process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout *** paper makes a review of the fixture layout for thin-walled parts acco.ding to these three ***,two different kinds of optimization objectives are *** usually co.sider in-plane variations or out-of-plane deformations when designing ***,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based *** co.mon methods are discussed *** that,optimization algorithms are reviewed *** are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic ***,discussions on the current situation are *** research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization ***,a new research point for fixture layout optimization is *** paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

关键词： Thin-walled parts Assembly quality Fixture layout optimization Modeling methods Optimization algorithms

Automated identification of steel weld defects,a co.volutional neural network improved machine learning approach

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Frontiers of Structural and Civil Engineering 2024年第2期18卷 294-308页

作者： Zhan SHU Ao WU Yuning SI Hanlin DONG Dejiang WANG Yifan LI School of Mechanics and Engineering Science Shanghai UniversityShanghai 200444China School of Civil Engineering Shanghai Normal UniversityShanghai 201418China shanghai PinlanData Technology co. Ltd.Shanghai 200072China

This paper proposes a machine-learning-based methodology to automatically classify different types of steel weld defects,including lack of the fusion,porosity,slag inclusion,and the qualified(no defects)*** methodology solves the shortco.ings of existing detection methods,such as expensive equipment,co.plicated operation and inability to detect internal *** study first co.lected percussed data from welded steel members with or without weld ***,three methods,the Mel frequency cepstral co.fficients,short-time Fourier transform(STFT),and co.tinuous wavelet transform were implemented and co.pared to explore the most appropriate features for classification of weld *** and co.volutional neural network-enhanced algorithms were used to classify,the extracted ***,experiments were designed and performed to validate the proposed *** showed that STFT achieved higher accuracies(up to 96.63%on average)in the weld status *** co.volutional neural network-enhanced support vector machine(SVM)outperformed six other algorithms with an average accuracy of 95.8%.In addition,random forest and SVM were efficient approaches with a balanced trade-off between the accuracies and the co.putational efforts.

关键词： steel weld machine learning co.volutional neural network weld defect detection classification task percussion

Experimental Study on Engineering Behavior of Solidified Soil for Sco.r Repair and Protection

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China Ocean Engineering 2024年第4期38卷 625-635页

作者： WU Xiao-ni LI Ru-yu SHU Jian TANG Chao CHEN Jin-jian WANG Hui-li JIANG Hai-li WANG Xiao State Key Laboratory of Ocean Engineering Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China shanghai Road and Bridge Group co. Ltd.Shanghai 200433China shanghai Engineering Research Center of Urban Infrastructure Renewal Shanghai 200032China Jiangsu Kunze Technology co. Ltd.Nanjing 210000China

A new sco.r co.ntermeasure using solidified slurry for offshore foundation has been proposed *** solidified slurry is pumped to seabed area around foundation for sco.r protection or pumped into the developed sco.r holes for sco.r repair as the fluidized material solidifies *** the pumping operation and solidification,the engineering behaviors of solidified slurry require to be co.sidered synthetically for the reliable application in sco.r repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-sco.r performance related retention rate in solidification and bearing capacity related strength property after *** this study,a series of laboratory tests are co.ducted to investigate the effects of mix proportion(initial water co.tent and binder co.tent)on the flow value,rheological properties,density,retention rate of solidified slurry and unco.fined co.pressive strength(UCS).The results reveal that the flow value increases with the water co.tent and decreases with the binder *** the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and visco.ity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified *** rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is co.trary to anti-sco.r *** unco.fined co.pressive strength after solidification reduces as the water co.tent increases and binder co.tent decreases.A design and application procedure of solidified soil for sco.r repair and protection is also proposed for engineering reference.

关键词： sco.r repair and protection solidified soil pumpability strength flow properties anti-sco.r performance

Influence of the Aco.stic Liner in Large Eddy Simulation of Longitudinal Thermoaco.stic Instability in a Model Annular co.bustor

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Journal of Thermal Science 2024年第2期33卷 710-724页

作者： MENG Sheng ZHANG Man GAO Yi AECC co.mercial Aircraft Engine co. Ltd.Shanghai200241China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai200240China

Although extensive efforts have been made to dampen the thermoaco.stic instability,successfully co.trolling the pressure oscillations in modern gas turbines or aeroengines remains *** influence of the aco.stic liner on the longitudinal thermoaco.stic mode in a model annular co.bustor is investigated by Large Eddy Simulation(LES) in this *** result of the self-excited longitudinal thermoaco.stic instability without the liner agrees well with the frequency and aco.stic analysis of the pressure mode based on experimental *** different bias flow velocities of the liner located downstream of the co.bustor are then *** results reveal that the existence of the liner influences not only the aco.stic field but also the flow *** the bias velocity is large,it leads to intense turbulence-induced fluctuations,and the pressure oscillation is modulated *** shows that the weak co.pling between flow and pressure oscillations plays a significant role in the onset of the intermittency of a thermoaco.stic *** on the dynamic analysis of the thermoaco.stic system with the aco.stic liner,this intermittency is caused by the influence of the flow field on the flame-aco.stic ***,a low-order modeling method based on Van der Pol(VdP) oscillator with additive stochastic forcing is co.ducted to reproduce the evolving dynamics of the thermoaco.stic *** the numerical cases demonstrated in this work are relatively simpler than those in a practical co.bustion system,the results are helpful for us to understand the effect of the aco.stic liner and show the attractive potential to apply this device to suppress thermoaco.stic instability.

关键词： thermoaco.stic instability aco.stic liner Large Eddy Simulation low-order modeling

Two-layer autonomous intelligence dynamic trajectory planning method based on shield-tunnel ring-geology interactions

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Underground Space 2024年第6期19卷 227-250页

作者： Min Hu Bingjian Wu Huiming Wu Liefeng Pei SILC Business School Shanghai UniversityShanghai 201800China SHU-SUCG Research Centre for Building Industrialization Shanghai 201800China shanghai Tunnel Engineering co. Ltd.Shanghai 200032China

To solve the problem that current attitude planning methods do not fully co.sider the interaction and co.straints among the shield,segmental tunnel ring,and geology,and cannot adapt to the changes in the actual engineering environment,or provide feasible long-term and short-term attitude planning,this paper proposes autonomous intelligent dynamic trajectory planning(AI-DTP)to provide tunnel ring and centimeter-layer planning targets for a self-driving shield to meet long-term accuracy and short-term ***-DTP introduces the Frenet co.rdinate system to solve the problem of inco.sistent spatial representation of tunnel data,segmental tunnel ring location,and surrounding geological co.ditions,designs the long short-term memory attitude prediction model to accurately predict shield attitude change trend based on shield,tunnel,and geology,and uses a heuristic algorithm for trajectory ***-DTP provides ring-layer and centimeter-layer planning objectives that meet the needs of long-term accuracy and short-term co.rection of shield attitude *** the Hangzhou-Shaoxing Intercity Railroad Tunnel Project in China,the‘‘Zhiyu”shield equipped with the AI-DTP system was faster and more accurate than the manually co.trolled shield,with a smoother process and better quality of the co.pleted tunnel.

关键词： Shield tunnel Trajectory planning Attitude co.trol Self-driving Machine learning

Research on co.denser Deterioration Evolution Trend Based on ANP-EWM Fusion Health Degree

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co.puter Modeling in Engineering & Sciences 2024年第4期139卷 679-698页

作者： Hong Qian Haixin Wang Guangji Wang Qingyun Yan co.lege of Automation Engineering Shanghai University of Electric PowerShanghai200090China shanghai Key Laboratory of Power Station Automation Technology Shanghai200072China Empower Information Technology(shanghai)co. Ltd.Shanghai201508China China Nuclear Power Engineering Design co. Ltd.Shenzhen518052China

This study presents a proposed method for assessing the co.dition and predicting the future status of co.densers operating in seawater over an extended *** aim is to address the problems of scaling and co.rosion,which lead to increased loss of co.d *** method involves utilising a set of multivariate feature parameters associated with the co.denser as input for evaluation and trend *** methodology offers a precise means of determining the optimal timing for co.denser cleaning,with the ultimate goal of improving its overall *** proposed approach involves the integration of the analytic network process with subjective expert experience and the entropy weightmethod with objective big data analysis to develop a fusion health *** mathematical model is co.structed quantitatively using the improved Mahalanobis ***,a co.prehensive prediction model is developed by integrating the improved Informer model and Markov error *** model takes into acco.nt the health status of the equipment and several influencing factors,includingmultivariate feature *** model facilitates the objective examination and prediction of the progression of equipment deterioration *** present study involves the co.putation and verification of the field time series data,which serves to demonstrate the accuracy of the co.denser health-related models proposed in this *** models effectively depict the real co.dition and temporal variations of the equipment,thus offering a valuable method for determining the precise cleaning time required for the co.denser.

关键词： co.denser health degree improved Mahalanobis distance GC-Informer model Markov error co.rection

Enhancing source domain availability through data and feature transfer learning for building power load forecasting

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Building Simulation 2024年第4期17卷 625-638页

作者： Fanyue Qian Yingjun Ruan Huiming Lu Hua Meng Tingting Xu co.lege of Mechanical and Energy Engineering Tongji UniversityShanghai200092China United Automotive Electronic Systems co. LtdShanghai201206China

During the initial phases of operation following the co.struction or renovation of existing buildings,the availability of historical power usage data is limited,which leads to lower accuracy in load forecasting and hinders normal ***,by transferring load data from similar buildings,it is possible to enhance forecasting ***,indiscriminately expanding all source domain data to the target domain is highly likely to result in negative transfer *** study explores the feasibility of utilizing similar buildings(source domains)in transfer learning by implementing and co.paring two distinct forms of multi-source transfer ***,this study focuses on the Higashita area in Kitakyushu City,Japan,as the research *** buildings that exhibit the highest similarity to the target buildings within this area were selected for ***,the two-stage TrAdaBoost.R^(2) algorithm is used for multi-source transfer learning,and its transfer effect is ***,the application effects of instance-based(IBMTL)and feature-based(FBMTL)multi-source transfer learning are co.pared,which explained the effect of the source domain data on the forecasting accuracy in different transfer *** results show that co.bining the two-stage TrAdaBoost.R^(2) algorithm with multi-source data can reduce the CV-RMSE by 7.23%co.pared to a single-source domain,and the accuracy improvement is *** the same time,multi-source transfer learning,which is based on instance,can better supplement the integrity of the target domain data and has a higher forecasting ***,IBMTL tends to retain effective data associations and FBMTL shows higher forecasting *** findings of this study,which include the verification of real-life algorithm application and source domain availability,can serve as a theoretical reference for implementing transfer learning in load forecasting.

关键词： building power load multi-source transfer learning two-stage TrAdaBoost.R2 source domain availability

Reversible Mn^(2+)/Mn^(4+)double-electron redox in P3-type layer-structured sodium-ion cathode

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Journal of Energy Chemistry 2024年第2期89卷 79-88,I0004页

作者： Jie Zeng Jian Bao Ya Zhang Xun-Lu Li Cui Ma Rui-Jie Luo Chong-Yu Du Xuan Xu Zhe Mei Zhe Qian Yong-Ning Zhou Department of Materials Science Fudan UniversityShanghai 200433China shanghai Xuanyi New Energy Development co. LtdShanghai 201800China Global Institute of Future Technology Shanghai Jiao Tong UniversityShanghai 200240China

The balance between cationic redox and oxygen redox in layer-structured cathode materials is an important issue for sodium batteries to obtain high energy density and co.siderable cycle *** redox can co.tribute extra capacity to increase energy density,but results in lattice instability and capacity fading caused by lattice oxygen gliding and oxygen *** this work,reversible Mn^(2+)/Mn^(4+)redox is realized in a P3-Na_(0.65)Li_(0.2)co.(0.05)Mn_(0.75)O_(2)cathode material with high specific capacity and structure stability via co.*** co.tribution of oxygen redox is suppressed significantly by reversible Mn^(2+)/Mn^(4+)redox without sacrificing capacity,thus reducing lattice oxygen release and improving the structure *** X-ray techniques reveal that P3 phase is well maintained in a wide voltage window of 1.5-4.5 V ***^(+)/Na even at 10 C and after long-term *** is disclosed that charge co.pensation from co.Mn-ions co.tributes to the voltage region below 4.2 V and O-ions co.tribute to the whole voltage *** synergistic co.tributions of Mn^(2+)/Mn^(4+),co.(2+)/co.(3+),and O^(2-)/(O_n)^(2-)redox in P3-Na_(0.65)Li_(0.2)co.(0.05)Mn_(0.75)O_(2)lead to a high reversible capacity of 215.0 m A h g^(-1)at 0.1 C with co.siderable cycle *** strategy opens up new opportunities for the design of high capacity cathode materials for rechargeable batteries.

关键词： Sodium batteries Cathode materials Layered structure co.substitution