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Fault diagnosis of HVAC system with imbalanced data using multi-scale convolution composite neural network

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Building Simulation 2024年第3期17卷 371-386页

作者： Rouhui Wu yizhu Ren Mengying Tan Lei nie School of Mechanical Engineering Hubei University of TechnologyWuhan430068China Industrial Research Institute of Xiangyang Hubei University of Technology Xiangyang441100China

Accurate fault diagnosis of heating,ventilation,and air conditioning(HVAC)systems is of significant importance for maintaining normal operation,reducing energy consumption,and minimizing maintenance ***,in practical applications,it is challenging to obtain sufficient fault data for HVAC systems,leading to imbalanced data,where the number of fault samples is much smaller than that of normal ***,most existing HVAC system fault diagnosis methods heavily rely on balanced training sets to achieve high fault diagnosis ***,to address this issue,a composite neural network fault diagnosis model is proposed,which combines SMOTETomek,multi-scale one-dimensional convolutional neural networks(M1DCNN),and support vector machine(SVM).This method first utilizes SMOTETomek to augment the minority class samples in the imbalanced dataset,achieving a balanced number of faulty and normal ***,it employs the M1DCNN model to extract feature information from the augmented ***,it replaces the original Softmax classifier with an SVM classifier for classification,thus enhancing the fault diagnosis *** the SMOTETomek-M1DCNN-SVM method,we conducted fault diagnosis validation on both the ASHRAE RP-1043 dataset and experimental dataset with an imbalance ratio of 1:*** results demonstrate the superiority of this approach,providing a novel and promising solution for intelligent building management,with accuracy and F1 scores of 98.45%and 100%for the RP-1043 dataset and experimental dataset,respectively.

关键词： fault diagnosis chiller imbalanced data SMOTETomek multi-scale neural networks

A reduced-order model for fast predicting ionized flows of hypersonic vehicles along flight trajectory

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Chinese Journal of Aeronautics 2024年第1期37卷 89-105页

作者： jingchao ZHANG Chunsheng nie Jinsheng CAI Shucheng PAN School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Science and Technology on Space Physics Laboratory China Academy of Launch Vehicle TechnologyBeijing 100076China Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China

An improved Reduced-Order Model(ROM)is proposed based on a flow-solution preprocessing operation and a fast sampling strategy to efficiently and accurately predict ionized hypersonic *** ROM is generated in low-dimensional space by performing the Proper Orthogonal Decomposition(POD)on snapshots and is coupled with the Radial Basis Function(RBF)to achieve fast prediction ***,due to the disparate scales in the ionized flow field,the conventional ROM usually generates spurious negative ***,this issue is addressed by performing flow-solution preprocessing in logarithmic space to improve the conventional ***,extra orthogonal polynomials are introduced in the RBF interpolation to achieve additional improvement of the prediction *** addition,to construct high-efficiency snapshots,a trajectory-constrained adaptive sampling strategy based on convex hull optimization is *** evaluate the performance of the proposed fast prediction method,two hypersonic vehicles with classic configurations,i.e.a wave-rider and a reentry capsule,are used to validate the proposed *** two cases show that the proposed fast prediction method has high accuracy near the vehicle surface and the free-stream region where the flow field is *** with the conventional ROM prediction,the prediction results are significantly improved by the proposed method around the discontinuities,*** shock wave and the ionized *** a result,the proposed fast prediction method reduces the error of the conventional ROM by at least 45%,with a speedup of approximately 2.0×105compared to the Computational Fluid Dynamic(CFD)*** test cases demonstrate that the method developed here is efficient and accurate for predicting ionized hypersonic flows.

关键词： Reduced-order model Radial basis function Constrained sampling Transfer function Fast flow prediction Ionized hypersonic flows

Fluid-structure interaction simulation for multi-body flexible morphing structures

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Chinese Journal of Aeronautics 2024年第2期37卷 137-147页

作者： Wenzhi GUO Yongtao SHUI Lu nie Gang CHEN State Key Laboratory of Strength and Vibration for Mechanic Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China China Academy of Launch Vehicle Technology Beijing 100076China China Academy of Aerospace Science and Innovation Beijing 100086China Shannxi Key Laboratory of Service Environment and Control for Flight Vehicles Xi’an Jiaotong UniversityXi’an 710049China

The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions *** researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive ***,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further *** this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation *** numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability *** the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.

关键词： Fluid-structure interaction Multi-body dynamics modeling Flexible structures Aerodynamics Morphing wings

Bulging Distortion of Austenitic Stainless Steel Sheet on the Partially Penetrated Side of Non-Penetration Lap Laser Welding Joint

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 286-295页

作者： Chengwu Yao Enze Liu Jiaming Ni Binying nie Shanghai Key Laboratory of Materials Laser Processing and Modification School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Aerospace Precision Machinery Institute Shanghai 201600China Chemical and Biological Engineering College Yichun UniversityYichun 336000China

Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost ***,the application of non-penetration welded austenitic stainless steel parts is limited owing to the micro bulging distortion that occurs on the back surface of the partial penetration *** this paper,non-penetration lap laser welding experiments,were conducted on galvanized and SUS304 austenitic stainless steel plates using a fiber laser,to investigate the mechanism of bulging distortion.A comparative experiment of DC01 galvanized steel-Q235 carbon steel lap laser welding was carried out,and the deflection and distortion profile of partially penetrated side of the sheets were measured using a noncontact laser *** addition,the cold-rolled SUS304 was subjected to heat holding at different temperatures and water quenching after bending to characterize its microstructure under tensile and compressive *** results show that,during the heating stage of the thermal cycle of laser lap welding,the partial penetration side of the SUS304 steel sheet generates compressive stress,which extrudes the material in the heat-affected zone to the outside of the back of the SUS304 steel sheet,thereby forming a *** findings of these experiments can be of great value for controlling the distortion of the partial penetrated side of austenitic stainless steel sheet during laser non-penetration lap welding.

关键词： Non-penetration lap laser welding Bulging distortion Austenitic stainless steel Compressive stress Tension stress

Passive particles driven by self-propelled particle:The wake effect

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Chinese Physics B 2024年第4期33卷 500-507页

作者：郑凯选汪静文王世锋聂德明 Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310018China Department of Mechanical Engineering Hangzhou Vocational&Technical CollegeHangzhou 310018China

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's *** research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's *** stronger dipolarity of squirmer results in an increased critical capture ***,the Reynolds number is found to have minimal influence on this ***,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's *** results in a mutual acceleration for both *** findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

关键词： lattice Boltzmann method(LBM) self-propelled particles particle-laden flow

Reverse metabolomics as a novel strategy to annotate the human metabolome

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Chinese Journal of Natural Medicines 2024年第4期22卷 289-290页

作者： YAN Tingting nie Liangliang HAO Haiping State Key Laboratory of Natural Medicines China Pharmaceutical UniversityNanjing 211198China Laboratory of Metabolic Regulation and Drug Target Discovery School of PharmacyChina Pharmaceutical UniversityNanjing 210009China

Identifying chemical structures inhuman-derived samples presents significant challenges due to limited structural data obtained from untargeted metabolomics *** the chemical structures of molecules are closely related to the phenotypic status of human ecosystems,it becomes invaluable to devise a method for efficiently and systematically determining structures that correlate with the pathophysiological status of humans in a high-throughput approach.

关键词： Reverse metabolomics Human metabolome Combinational synthesis Bile amidates

Autophagy Alleviates Cold Exposure-induced Tight Junction Injury in Murine Ileum

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Biomedical and Environmental Sciences 2024年第7期37卷 800-804页

作者： jingru Guo jing Xu Leichong Chen Huijie Hu Junshu nie Jianbin Yuan Li Ma jingjing Lu Hong Ji Bin Xu Key Laboratory of Bovine Disease Control in Northeast China Ministry of Agriculture and Rural affairsHeilongjiang Provincial Key Laboratory of Prevention and Control of Bovine DiseasesCollege of Animal Science and Veterinary MedicineHeilongjiang Bayi Agricultural UniversityDaqing 163319HeilongjiangChina

Cold exposure is a pervasive stressor in the polar and subpolar regions,exerting both acute and chronic effects on *** environmental factor is known to induce physiological stress,compromise immune response efficacy,and increase susceptibility to various *** cold exposure,characterized by repetitive nonconsecutive exposure to suboptimal temperatures over an extended duration.

关键词： acute exposure susceptibility

Natural forests exhibit higher organic carbon concentrations and recalcitrant carbon proportions in soil than plantations:a global data synthesis

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Journal of Forestry Research 2024年第5期35卷 131-141页

作者： Xiuqing nie Hui Wang Jian Wang Shirong Liu Ecology and Nature Conservation Institute Chinese Academy of ForestryKey Laboratory of Forest Ecology and Environment of National Forestry and Grassland AdministrationNo.2 DongxiaofuHaidian DistrictBeijing 100091People’s Republic of China

Different chemical compositions of soil organic carbon(SOC)affect its persistence and whether it signifi-cantly differs between natural forests and plantations remains *** synthesizing 234 observations of SOC chemical compositions,we evaluated global patterns of concentra-tion,individual chemical composition(alkyl C,O-alkyl C,aromatic C,and carbonyl C),and their distribution *** results indicate a notably higher SOC,a markedly larger proportion of recalcitrant alkyl C,and lower easily decomposed carbonyl C proportion in natural ***-ever,SOC chemical compositions were appreciably more evenly distributed in *** on the assumed con-ceptual index of SOC chemical composition evenness,we deduced that,compared to natural forests,plantations may have higher possible resistance to SOC decomposition under *** tropical regions,SOC levels,recalcitrant SOC chemical composition,and their distributed evenness were significantly higher in natural forests,indicating that SOC has higher chemical stability and possible resistance to *** factors had minor effects on alkyl C in forests globally,while they notably affected SOC chemi-cal composition in tropical *** could contribute to the differences in chemical compositions and their distrib-uted evenness between plantations and natural stands.

关键词： Global data synthesis Natural forest Plantations Soil organic carbon Soil organic carbon chemical composition

Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

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Research 2024年第1期2023卷 209-236页

作者： Feng Tian Zhongya Pang Shen Hu Xueqiang Zhang Fei Wang Wei nie Xuewen Xia Guangshi Li Hsien-yi Hsu Qian Xu Xingli Zou Li Ji Xionggang Lu State Key Laboratory of Advanced Special Steel&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai University99#Shangda RoadShanghai 200444China Center for Hydrogen Metallurgy Technology Shanghai UniversityShanghai 200444China State Key Laboratory of ASIC and System School of MicroelectronicsFudan University220#Handan RoadShanghai 200433China School of Energy and Environment Department of Materials Science and EngineeringCity University of Hong KongKowloon TongHong KongChina

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science ***,considered a promising strategy,has been explored to produce silicon due to prominent advantages:(a)high electricity utilization efficiency;(b)low-cost silica as a raw material;and(c)tunable morphologies and structures,including films,nanowires,and *** review begins with a summary of early research on the extraction of silicon by *** has been placed on the electro-deoxidation and dissolution–electrodeposition of silica in chloride molten salts since the 21st century,including the basic reaction mechanisms,the fabrication of photoactive Si films for solar cells,the design and production of nanoSi and various silicon components for energy conversion,as well as storage ***,the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are *** this basis,the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed,which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

关键词： directions electrodeposition electricity