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Improved CICA Algorithm Used for Single Channel Compound Fault Diagnosis of Rolling Bearings

Chinese Journal of mechanical Engineering 2016年第1期29卷 204-211页

作者： CHEN Guohua QIE Longfei ZHANG Aijun HAN Jin College of mechanical and electrical Engineering Beijing University of Chemical Technology School of mechanical Engineering Beijing Institute of Technology

A Compound fault signal usually contains multiple characteristic signals and strong confusion noise, which makes it difficult to separate week fault signals from them through conventional ways, such as FFT-based envelope detection, wavelet transform or empirical mode decomposition individually. In order to realize single channel compound fault diagnosis of bearings and improve the diagnosis accuracy, an improved CICA algorithm named constrained independent component analysis based on the energy method （E-CICA） is proposed. With the approach, the single channel vibration signal is firstly decomposed into several wavelet coefficients by discrete wavelet transform（DWT） method for the purpose of obtaining multichannel signals. Then the envelope signals of the reconstructed wavelet coefficients are selected as the input of E-CICA algorithm, which fulfills the requirements that the number of sensors is greater than or equal to that of the source signals and makes it more suitable to be processed by CICA strategy. The frequency energy ratio（ER） of each wavelet reconstructed signal to the total energy of the given synchronous signal is calculated, and then the synchronous signal with maximum ER value is set as the reference signal accordingly. By this way, the reference signal contains a priori knowledge of fault source signal and the influence on fault signal extraction accuracy which is caused by the initial phase angle and the duty ratio of the reference signal in the traditional CICA algorithm is avoided. Experimental results show that E-CICA algorithm can effectively separate out the outer-race defect and the rollers defect from the single channel compound fault and fulfill the needs of compound fault diagnosis of rolling bearings, and the running time is 0.12% of that of the traditional CICA algorithm and the extraction accuracy is 1.4 times of that of CICA as well. The proposed research provides a new method to separate single channel compound fault signals.

关键词： compound fault diagnosis, energy method constrained independent component analysis(CICA) diserete wavelet transform(DWT)

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Controllable self-transport of bouncing droplets on ultraslippery surfaces with wedge-shaped grooves

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Droplet 2024年第2期3卷 138-145页

作者： Chuchen Yue Qingwen Dai Xiaolong Yang Carsten Gachot Wei Huang Xiaolei Wang College of mechanical and electrical Engineering Nanjing University of Aeronautics&AstronauticsNanjingChina institute of Engineering design and Product Development Tribology Research GroupTU WienViennaAustria

Preventing the accretion of droplets on surfaces is vital and slippery liquid-infused porous surfaces(SLIPS)have promising application prospects,such as surface self-cleaning and droplet *** this work,controllable self-transport of bouncing droplets on ultraslippery surfaces with wedge-shaped grooves is *** impact behaviors of droplets on SLIPS under various impact velocities and diameters are explored,which can be classified as hover,total bounce,partial bounce,Worthington jet,and *** with wedge-shaped grooves were designed to transport accreted *** energy and transport model is established to explain the impact and self-transport mechanism,where the Laplace pressure and moving resistance between droplets play a key ***,SLIPS with branched wedge-shaped grooves were designed for droplet self-transport and demonstrated *** work provides a general reference for spontaneous motion control of sessile droplets,droplets with initial impacting velocity,or even liquid films.

关键词： wedge shaped droplets

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Movement Modeling and Control for Robotic Bonnet Polishing

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Chinese Journal of mechanical Engineering 2022年第3期35卷 211-218页

作者： Xuepeng Huang Zhenzhong Wang Zewen Lin Department of mechanical and electrical Engineering Xiamen UniversityXiamen 361005China Shenzhen research institute of Xiamen University Shenzhen 518057China

With the increasing demand for high-precision optical components,bonnet polishing technology is increasingly being used in the polishing process of optical components owing to its high removal efficiency and high surface ***,it is expensive and difficult to implement dedicated bonnet polishing machine tools,and their processing range is *** research combines bonnet polishing technology with industrial robot-assisted processing technology to propose a robotic bonnet polishing control model for large-diameter axisymmetric aspherical optical *** the transformation relations of the spatial coordinate system,the transformation relations of the workpiece coordinate system,local coordinate system of the polishing point,and tool coordinate system of the bonnet sphere center are established to obtain the bonnet precession polishing motion *** polishing trajectory of large-diameter axisymmetric aspherical components and the variation in the linkage angle difference were simulated by adding an efficiency-optimal control strategy to the motion *** robot motion was simulated in Robostudio to verify the correctness of the precession motion model and control ***,the robotic bonnet polishing system was successfully applied to the polishing process of the optical components.

关键词： Industrial robot Bonnet polishing Precession movement Control algorithm

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SOME IMPROVEMENTS IN VISCO-PLASTIC MODEL CONSIDERING DYNAMIC RECRYSTALLIZATION

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Acta Mechanica Sinica 2004年第5期20卷 499-506页

作者：曲杰金泉林徐秉业 Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China Beijing research institute of mechanical and electrical Technology Beijing 100083China

Some improvements in Jin's thermal visco-plastic constitutive model considering dy- namic recrysytallization is presented in this *** introducing the influence of the strain rate on the mobility of dynamic recovery,the improved model can be more smoothly applied to numeri- cal simulation of material flow behaviour and microstructure prediction during hot *** improvement is to consider the accumulated dislocation energy in the newly recrystallized grains as a resistance to the driving force of dynamic recrystallization *** improvement makes the predicted results of dynamic recrystallization progress agree better with the actual physical process. Finally,some numerical examples are given to show the advantages of the improved model and the ability to predict the dynamic recrystallization.

关键词： microstructures constitutive model dynamic recrystallization

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Mission decision-making method of multi-aircraft cooperatively attacking multi-target based on game theoretic framework

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Chinese Journal of Aeronautics 2016年第6期29卷 1685-1694页

作者： Yao Zongxin Li Ming Chen Zongji Zhou Rui Shenyang Aircraft design and research institute Shenyang 110035China School of Automation Science and electrical Engineering Beihang UniversityBeijing 100083China

Coordinated mission decision-making is one of the core steps to effectively exploit the capabilities of cooperative attack of multiple aircrafts. However, the situational assessment is an essential base to realize the mission decision-making. Therefore, in this paper, we develop a mission decision-making method of multi-aircraft cooperatively attacking multi-target based on situational assessment. We have studied the situational assessment mathematical model based on the Dempster-Shafer(D-S) evidence theory and the mission decision-making mathematical model based on the game theory. The proposed mission decision-making method of antagonized airfight is validated by some simulation examples of a swarm of unmanned combat aerial vehicles(UCAVs)that carry out the mission of the suppressing of enemy air defenses(SEAD).

关键词： Antagonized airfight D-S evidence theory Fuzzy mapping function Game theoretic framework Mission decision-making Multi-aircraft coordination Situational assessment

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A frequency domain reliability analysis method for electromagnetic problems based on univariate dimension reduction method

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Science China(Technological Sciences) 2019年第5期62卷 787-798页

作者： PING MengHao HAN Xu JIANG Chao ZHONG JianFeng XIAO XiaoYa HUANG ZhiLiang WANG ZhongHua State Key Laboratory of Advanced design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan University Nanjing research institute of Electronics Technology

In this paper, a class of electromagnetic field frequency domain reliability problem is first defined. The frequency domain reliability refers to the probability that an electromagnetic performance indicator can meet the intended requirements within a specific frequency band, considering the uncertainty of structural parameters and frequency-variant electromagnetic *** then a frequency domain reliability analysis method based on univariate dimension reduction method is proposed, which provides an effective calculation tool for electromagnetic frequency domain reliability. In electromagnetic problems, performance indicators usually vary with frequency. The method firstly discretizes the frequency-variant performance indicator function into a series of frequency points' functions, and then transforms the frequency domain reliability problem into a series system reliability problem of discrete frequency points' functions. Secondly, the univariate dimension reduction method is introduced to solve the probability distribution functions and correlation coefficients of discrete frequency points' functions in the system. Finally, according to the above calculation results, the series system reliability can be solved to obtain the frequency domain reliability, and the cumulative distribution function of the performance indicator can also be obtained. In this study,Monte Carlo simulation is adopted to demonstrate the validity of the frequency domain reliability analysis method. Three examples are investigated to demonstrate the accuracy and efficiency of the proposed method.

关键词： electromagnetic field frequency domain reliability system reliability random process discretization univariate dimension reduction method

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Energy and comfort performance of occupant-centric air conditioning strategy in office buildings with personal comfort devices

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Building Simulation 2022年第5期15卷 899-911页

作者： Jingsi Zhang Xiang Zhou Song Lei Maohui Luo School of mechanical Engineering Tongji UniversityShanghai 200092China East China Architectural design and research institute 151 Hankou RoadShanghaiChina

The personal comfort system(PCS)aims to meet individual thermal comfort demands efficiently to achieve higher thermal comfort satisfaction while reducing air conditioning energy *** date,many PCS devices have been developed and evaluated from the perspective of thermal *** will be useful for future PCS development if an approach to quantify the thermal comfort and energy performance of certain PCS devices and their combinations with consideration of user behaviors can be *** study attempted to fill this gap by integrating thermal comfort experiments,occupancy simulations,usage behavior modeling,and building energy simulation ***,human subject experiments were conducted to quantify the thermal comfort effects of the ***,the Markov chain model and conditional probability model were employed to describe the room occupancy and PCS usage ***,the extended comfort temperature range and user behavior models were imported into the building energy simulation tool to analyze the energy-saving potential of the *** results show that the use of PCS can significantly improve occupants,thermal comfort and satisfaction rate under both warm and cool *** a cooling cushion and desktop fan can lift the upper limit of the comfortable temperature to 29.5℃while the heated cushion can extend the lower limit to 15℃.By increasing the air conditioning temperature setpoint by 2℃in summer and reducing by 2.5℃the heating temperature setpoint in winter,PCS devices can reduce heating and air conditioning energy consumption by 25%-40%while maintaining occupants’thermal comfort.

关键词： thermal comfort personal comfort system occupant behavior building energy simulation building energy saving

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Direct-Ink-Writing Printed Strain Rosette Sensor Array with Optimized Circuit Layout

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Chinese Journal of mechanical Engineering 2023年第4期36卷 205-211页

作者： Peishi Yu Lixin Qi Zhiyang Guo Yu Liu Junhua Zhao Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology School of Mechanical EngineeringJiangnan UniversityWuxi 214122China Jiangsu Province Engineering research Center of Micro-Nano Additive and Subtractive Manufacturing Institute of Advanced TechnologyJiangnan UniversityWuxi 214122China

The full-field multiaxial strain measurement is highly desired for application of structural monitoring but still challenging,especially when the manufacturing and assembling for largearea sensing devices is quite *** with the traditional procedure of gluing commercial strain gauges on the structure surfaces for strain monitoring,the recently developed Direct-Ink-Writing(DIW)technology provides a feasible way to directly print sensors on the ***,there are still crucial issues in the design and printing strategies to be probed and ***,in this work,we propose an integrated strategy from layered circuit scheme to rapid manufacturing of strain rosette sensor array based on the DIW *** from the innovative design with simplified circuit layout and the advantages of DIW for printing multilayer structures,here we achieve optimization design principle for strain rosette sensor array with scalable circuit layout,which enable a hierarchical printing strategy for multiaxial strain monitoring in large scale or multiple *** strategy is highly expected to adapt for the emerging requirement in various applications such as integrated soft electronics,nondestructive testing and small-batch medical devices.

关键词： Direct-ink-writing Strain rosette sensor array Layered circuit scheme Printing strategy

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Forces and Stresses During Friction Stir Joining of 2024 Aluminum Alloy

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第2期33卷 237-242页

作者： Deng Yongfang Zuo Dunwen Song Bo College of mechanical & electrical Engineering Nanjing University of Aeronautics and Astronautics institute of Engineering and research Jiangxi University of Science and Technology

An attempt is made to measure three direction forces using octagonal ring dynamometer in the 2024 aluminum alloy friction stir joining(FSJ)process.A test is made to measure the specific area stress and stress distributions in the specific area of the workpiece are *** workpiece stresses in the FSJ process are analyzed by numerical simulation *** is found that,in the downward stage of the process,feed force and lateral force in the tool are small,almost zero,and the maximum axial force can reach *** the stable joining stage,the forces acting on the tool become *** with the low speed,high feed speed results in small feed force and small lateral force,but large feed force in the stable joining *** stresses in three directions of feed direction,direction that perpendicular to butt face and direction perpendicular to the surface are *** simulation stress value of measure point is *** and numerical simulation can authenticate each *** experimental stress values and numerical simulation stress values are credible.

关键词： friction stir joining(FSJ) force stress 2024 aluminum alloy

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Resilience Augmentation in Unmanned Weapon Systems via Multi-Layer Attention Graph Convolutional Neural Networks

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Computers, Materials & Continua 2024年第8期80卷 2941-2962页

作者： Kexin Wang Yingdong Gou Dingrui Xue Jiancheng Liu Wanlong Qi Gang Hou Bo Li Northwest institute of mechanical and electrical Engineering Xianyang712099China

The collective Unmanned Weapon System-of-Systems(UWSOS)network represents a fundamental element in modern warfare,characterized by a diverse array of unmanned combat platforms interconnected through hetero-geneous network *** its strategic importance,the UWSOS network is highly susceptible to hostile infiltrations,which significantly impede its battlefield recovery *** methods to enhance network resilience predominantly focus on basic graph relationships,neglecting the crucial higher-order dependencies among nodes necessary for capturing multi-hop meta-paths within the *** address these limitations,we propose the Enhanced-Resilience Multi-Layer Attention Graph Convolutional Network(E-MAGCN),designed to augment the adaptability of *** approach employs BERT for extracting semantic insights from nodes and edges,thereby refining feature representations by leveraging various node and edge ***,E-MAGCN integrates a regularization-based multi-layer attention mechanism and a semantic node fusion algo-rithm within the Graph Convolutional Network(GCN)*** extensive simulation experiments,our model demonstrates an enhancement in resilience performance ranging from 1.2% to 7% over existing algorithms.

关键词： Resilience enhancement heterogeneous network graph convolutional network

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