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Chinese Journal of mechanical Engineering 2024年第2期37卷 264-282页

作者： Xin Pan Xiancheng Zhang Zhinong Jiang Guangfu Bin Beijing Key Laboratory of Health Monitoring and Self-recovery for High-End mechanical Equipment College of Mechanical and Electrical EngineeringBeijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Engine Health Monitoring-Control and Networking(Ministry of Education) College of Mechanical and Electrical EngineeringBeijing University of Chemical TechnologyBeijing 100029China college of mechanical Engineering Hunan University of Science and TechnologyXiangtan 411201China

The co-frequency vibration fault is one of the common faults in the operation of rotating equipment,and realizing the real-time diagnosis of the co-frequency vibration fault is of great significance for monitoring the health state and carrying out vibration suppression of the *** engineering scenarios,co-frequency vibration faults are highlighted by rotational frequency and are difficult to identify,and existing intelligent methods require more hardware conditions and are exclusively ***,Lightweight-convolutional neural networks(LW-CNN)algorithm is proposed in this paper to achieve real-time fault *** critical parameters are discussed and verified by simulated and experimental signals for the sliding window data augmentation *** on LW-CNN and data augmentation,the real-time intelligent diagnosis of co-frequency is ***,a real-time detection method of fault diagnosis algorithm is proposed for data acquisition to fault *** is verified by experiments that the LW-CNN and sliding window methods are used with high accuracy and real-time performance.

关键词： Co-frequency vibration Real-time diagnosis LW-CNN Data augmentation

Analysis of the Erosion-Corrosion Mechanism of the Air Cooler in a Hydrocracking Unit:A Numerical and Experimental Study

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China Petroleum Processing & Petrochemical technology 2024年第1期26卷 126-138页

作者： Su Guoqing Li Yan Guo Hongli Zhang Jianwen college of mechanical and electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China

Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the *** analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air *** fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air *** results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler *** flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted *** initiation mechanism and processes leading to the development of E-C in the air cooler were also *** study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation.

关键词： air cooler hydrocracking unit erosion-corrosion simulation visualization experiment multiphase flow

Effect of nitrile butadiene rubber hardness on the sealing characteristics of hydraulic O-ring rod seals

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 63-78页

作者： Xiaoxuan LI Bingqing WANG Xudong PENG Yuntang LI Xiaolu LI Yuan CHEN Jie JIN college of Quality and Safety Engineering China Jiliang UniversityHangzhou310018China college of mechanical and electrical Engineering China Jiliang UniversityHangzhou310018China college of mechanical Engineering Zhejiang University of TechnologyHangzhou310023China

The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic *** studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of *** optimized selections of rubber hardness are then investigated under different *** show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions;it is also more prone to leaking.A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear *** choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.

关键词： Nitrile butadiene rubber(NBR)hardness Sealing characteristics Optimized selection O-ring seal

An Imbalanced Data Classification Method Based on Hybrid Resampling and Fine Cost Sensitive Support Vector Machine

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Computers, Materials & Continua 2024年第6期79卷 3977-3999页

作者： Bo Zhu Xiaona Jing Lan Qiu Runbo Li college of mechanical and electrical Engineering Kunming University of Science&TechnologyKunming650500China

When building a classification model,the scenario where the samples of one class are significantly more than those of the other class is called data *** imbalance causes the trained classification model to be in favor of the majority class(usually defined as the negative class),which may do harm to the accuracy of the minority class(usually defined as the positive class),and then lead to poor overall performance of the model.A method called MSHR-FCSSVM for solving imbalanced data classification is proposed in this article,which is based on a new hybrid resampling approach(MSHR)and a new fine cost-sensitive support vector machine(CS-SVM)classifier(FCSSVM).The MSHR measures the separability of each negative sample through its Silhouette value calculated by Mahalanobis distance between samples,based on which,the so-called pseudo-negative samples are screened out to generate new positive samples(over-sampling step)through linear interpolation and are deleted finally(under-sampling step).This approach replaces pseudo-negative samples with generated new positive samples one by one to clear up the inter-class overlap on the borderline,without changing the overall scale of the *** FCSSVM is an improved version of the traditional *** considers influences of both the imbalance of sample number and the class distribution on classification simultaneously,and through finely tuning the class cost weights by using the efficient optimization algorithm based on the physical phenomenon of rime-ice(RIME)algorithm with cross-validation accuracy as the fitness function to accurately adjust the classification *** verify the effectiveness of the proposed method,a series of experiments are carried out based on 20 imbalanced datasets including both mildly and extremely imbalanced *** experimental results show that the MSHR-FCSSVM method performs better than the methods for comparison in most cases,and both the MSHR and the FCSSVM played significan

关键词： Imbalanced data classification Silhouette value Mahalanobis distance RIME algorithm CS-SVM

Chain Rule for Extracting Resilience Procurement Costs from Locational Marginal Prices

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1342-1355页

作者： Yifei Wang Tong Zhu Tiancong Chen Mohammad Shahidehpour Qingshan Xu college of electrical Engineering Southeast UniversityNanjing 210096China Henan mechanical&electrical Vocational college Xinzheng 451191China Illinois Institute of technology ChicagoIllinois 60616USA IEEE CSEE

Power system resilience procurement costs in N-k contingencies have gained more prominence as number of extreme events continues to increase.A chain rule is presented in this paper for extracting resilience procurement costs from a fully decomposed locational marginal price(LMP)***,power transfer distribution factor(PTDF)matrices with AC power flow(i.e.,AC-PTDF)are ***-PTDF and AC-LODF(line outage distribution factor)equations are derived for N-k contingencies and a fully decomposed LMP model is developed where generation and transmission security components are established for specific ***,resilience procurement costs can be measured at different buses for the proposed security *** of N-k contingencies on resilience procurement costs at specific buses can be determined as proposed security components will gain more insight for resilience procurement in power *** modified IEEE 6-bus and 118-bus systems are adopted to verify effectiveness of the proposed resilience procurement method.

关键词： Line outage distribution factors locational marginal price power system resilience power transfer distribution factor security components

Blind Signal Reception in Downlink Generalized Spatial Modulation Multiuser MIMO System Based on Minimum Output Energy

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Chinese Journal of Electronics 2024年第2期33卷 504-515页

作者： Wei-Chiang WU college of mechanical and electrical Engineering Sanming University

This paper considers downlink multiuser multiple-input-multiple-output system with parallel spatial modulation scheme, in which base station transmitter antennas are separated into K groups corresponding to K user terminals. Generalized spatial modulation is employed, in which a subset(more than single antenna) of transmit antenna array are activated and the activating pattern corresponds to specific spatial symbol. Different from existing precoding-based algorithms, we develop a two-stage detection scheme at each user terminal: In the pre-processing stage, a minimax algorithm is proposed to identify the indices of active antennas, where the key idea is that the minimum output energy of the detector is maximized; A constrained minimum output energy algorithm is proposed in the post-processing stage to mitigate multiuser interference and extract temporal symbols. Compared with existing precoding-based algorithms, the complexity is significantly reduced. Moreover, the proposed algorithm is semi-blind,in which only a small subset of channel state information is required to identify active antennas as well as eliminate multiuser interference. Simulation results demonstrate that the proposed algorithm is near-far resistant and the spectral efficiency is extensively increased compared to the conventional spatial modulation scheme.

关键词： GSM Spectral efficiency Computer network reliability Transmitting antennas Modulation Symbols Downlink

Calculation and Analysis of TVMS Considering Profile Shifts and Surface Wear Evolution Process of Spur Gear

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Chinese Journal of mechanical Engineering 2024年第3期37卷 136-150页

作者： Wenzheng Liu Rupeng Zhu Wenguang Zhou Jingjing Wang college of mechanical and electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina

Profile shift is a highly effective technique for optimizing the performance of spur gear transmission ***,tooth surface wear is inevitable during gear meshing due to inadequate lubrication and long-term *** profile shift and tooth surface wear(TSW)can impact the meshing characteristics by altering the involute tooth *** this study,a tooth stiffness model of spur gears that incorporates profile shift,TSW,tooth deformation,tooth contact deformation,fillet-foundation deformation,and gear body structure coupling is *** model efficiently and accurately determines the time-varying mesh stiffness(TVMS).Additionally,an improved wear depth prediction method for spur gears is developed,which takes into consideration the mutually prime teeth numbers and more accurately reflects actual gear meshing *** show that consideration of the mutual prime of teeth numbers will have a certain impact on the TSW ***,the finite element method(FEM)is employed to accurately verify the values of TVMS and load sharing ratio(LSR)of profile-shifted gears and worn *** study quantitatively analyzes the effect of profile shift on the surface wear process,which suggests that gear profile shift can partially alleviate the negative effects of *** contribution of this study provides valuable insights into the design and maintenance of spur gear systems.

关键词： Profile shift Tooth surface wear Structure coupling effect Improved wear depth prediction method TVMS

Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

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Chinese Journal of mechanical Engineering 2024年第2期37卷 283-293页

作者： Guolong Chen Zheng Cao Shuaishuai Zhang Ji Wei Wei Gao Wuyin Jin School of mechanical and electrical Engineering Lanzhou University of TechnologyLanzhou 730050China

A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of ***,the extent of the lift-off effect on differential probes,including different coil structures,*** this study,two planar eddy current probes with differential pickup structures and the same size,Koch and circular probes,were used to compare lift-off *** eddy current distributions of the probes perturbed by 0°and 90°cracks were obtained by finite element *** analysis results show that the 90°crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off *** peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental *** addition,the effects of different frequencies on the lift-off were studied *** results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90°orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 *** addition,the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via *** indicates that the influence becomes more evident with an increase in excitation *** research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90°cracks at low lift-off distances.

关键词： Eddy current testing Differential pickup probe Fractal Koch curve Flexible eddy current probe

Cooperative control for heterogeneous multi-agent systems: progress, applications, and challenges

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Science China(Information Sciences) 2024年第5期67卷 318-320页

作者： Bing YAN Peng SHI Jonathon CHAMBERS School of electrical and mechanical Engineering Faculty of Science Engineering and TechnologyThe University of Adelaide School of Engineering College of Science and Engineering University of Leicester

Cooperative control for heterogeneous multi-agent systems(MASs) is a critical and rapidly evolving field in modern automation and robotics. Characterized by the integration of agents with diverse capabilities and func... 详细信息

关键词： Multi agent systems

Flat jet electrochemical milling of TC4 alloy with tailoring backward parallel flow

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Chinese Journal of Aeronautics 2024年第4期37卷 574-592页

作者： Huanghai KONG Ningsong QU college of mechanical and electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In flat jet electrochemical milling, the electrolyte forms a backward parallel flow after impacting the workpiece, resulting in a weak current density distribution on the workpiece. Poor surface quality usually occurs on the machined titanium alloy surface because it inevitably suffers from the weak current density. In this study, a method of flat jet electrochemical milling with tailoring the backward parallel flow was proposed to eliminate the negative effects caused by the weak current density. Multiphysics simulations are carried out to comprehend the mechanism of flat jetEC milling with tailoring backward parallel flow and better construct the novel tool *** on flat jet electrochemical milling of TC4 alloy with and without tailoring backward parallel flow are conducted. The results reveal that, compared with flat jet electrochemical milling without tailoring backward parallel flow, the recommended tool reduces the surface roughness by86% to 93%, and improves the material removal rate by 93% to 163% with different feed ***, the recommended tool is more conducive to maintaining the inherent hardness of the material. Finally, a surface with low Sa of 0.37 μm is obtained.

关键词： Flat jet electrochemical milling TC4 alloy Surface roughness Micro-hardness Material removal rate