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Iterative HOEO fusion strategy:a promising tool for enhancing bearing fault feature

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Frontiers of Mechanical Engineering 2023年第1期18卷 253-273页

作者： Xingxing JIANG Demin PENG Jianfeng GUO Jie LIU changqing shen Zhongkui ZHU School of Rail Transportation Soochow UniversitySuzhou 215131China China Academy of Railway Sciences Co.Ltd. Beijing 100094China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China

As parameter independent yet simple techniques,the energy operator(EO)and its variants have received considerable attention in the field of bearing fault feature ***,the performances of these improved EO techniques are subjected to the limited number of EOs,and they cannot reflect the non-linearity of the machinery dynamic systems and affect the noise *** a result,the fault-related transients strengthened by these improved EO techniques are still subject to contamination of strong *** address these issues,this paper presents a novel EO fusion strategy for enhancing the bearing fault feature nonlinearly and ***,the proposed strategy is conducted through the following three ***,a multi-dimensional information matrix(MDIM)is constructed by performing the higher order energy operator(HOEO)on the analysis signal *** is regarded as the fusion source of the proposed strategy with the properties of improving the signal-to-interference ratio and suppressing the noise in the low-frequency ***,an enhanced manifold learning algorithm is performed on the normalized MDIM to extract the intrinsic manifolds correlated with the fault-related ***,the intrinsic manifolds are weighted to recover the fault-related *** studies and experimental verifications confirm that the proposed strategy is more effective for enhancing the bearing fault feature than the existing methods,including HOEOs,the weighting HOEO fusion,the fast Kurtogram,and the empirical mode decomposition.

关键词： higher order energy operator fault diagnosis manifold learning rolling element bearing information fusion

Continual learning fault diagnosis:A dual-branch adaptive aggregation residual network for fault diagnosis with machine increments

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Chinese Journal of Aeronautics 2023年第6期36卷 361-377页

作者： Bojian CHEN changqing shen Juanjuan SHI Lin KONG Luyang TAN Dong WANG Zhongkui ZHU School of Rail Transportation Soochow UniversitySuzhou 215131China China Chang Guang Satellite Technology CO.LTD Changchun 130102China Department of Industrial Engineering and Management and in the State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200030China

As a data-driven approach, Deep Learning(DL)-based fault diagnosis methods need to collect the relatively comprehensive data on machine fault types to achieve satisfactory performance. A mechanical system may include multiple submachines in the real-world. During condition monitoring of a mechanical system, fault data are distributed in a continuous flow of constantly generated information and new faults will inevitably occur in unconsidered submachines, which are also called machine increments. Therefore, adequately collecting fault data in advance is difficult. Limited by the characteristics of DL, training existing models directly with new fault data of new submachines leads to catastrophic forgetting of old tasks, while the cost of collecting all known data to retrain the models is excessively high. DL-based fault diagnosis methods cannot learn continually and adaptively in dynamic environments. A new Continual Learning Fault Diagnosis method(CLFD) is proposed in this paper to solve a series of fault diagnosis tasks with machine increments. The stability–plasticity dilemma is an intrinsic issue in continual learning. The core of CLFD is the proposed Dual-branch Adaptive Aggregation Residual Network(DAARN).Two types of residual blocks are created in each block layer of DAARN: steady and dynamic blocks. The stability–plasticity dilemma is solved by assigning them with adaptive aggregation weights to balance stability and plasticity, and a bi-level optimization program is used to optimize adaptive aggregation weights and model parameters. In addition, a feature-level knowledge distillation loss function is proposed to further overcome catastrophic forgetting. CLFD is then applied to the fault diagnosis case with machine increments. Results demonstrate that CLFD outperforms other continual learning methods and has satisfactory robustness.

关键词： Catastrophic forgetting Continual learning Fault diagnosis Knowledge distillation Machine increments Stability-plasticity dilemma

Synchronous chirp mode extraction: A promising tool for fault diagnosis of rolling element bearings under varying speed conditions

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Chinese Journal of Aeronautics 2022年第1期35卷 348-364页

作者： Xingxing JIANG Qiang HUANG changqing shen Qian WANG Kun XU Jie LIU Juanjuan SHI Zhongkui ZHU School of Rail Transportation Soochow UniversitySuzhou 215131China Wenzheng College of Soochow University Suzhou 215104China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Sclool of Hydropower and Infonnation Engineering Huazhong University of Science and TechnologyWuhan 430074China

As critical components in modern aerospace productions,rolling element bearings(REBs)generally work under varying speed conditions,which brings great challenges to their operating health *** novel time–frequency decomposition(TFD)algorithms are established recently to extract nonlinear features from the non-stationary signals effectively,which are promising for realizing fault diagnosis of REBs under varying speed ***,numerous personal experiences must be incorporated and the anti-noise performance of these methods needs to be further *** these issues,a synchronous chirp mode extraction(SCME)-based REB fault diagnosis method is proposed for the health monitoring of REBs under varying speed conditions in this *** mainly consists of following two parts.(a)The shaft rotational frequency(SRF)is initially estimated from the low-frequency band of the vibration ***,an adaptive refining strategy is incorporated to obtain a suitable bandwidth parameter.(b)A cycle-one-step estimation frame is constructed to extract synchronous modes from the envelope waveform of the vibration ***,a synchronous mode spectrum(SMS)is generated using the information of the extracted synchronous modes,which is a novel REBs fault diagnosis technique with tacholess and *** contrast to the current TFD algorithms,the proposed method needs fewer input parameters and owns a well anti-noise performance because there is no iterative optimization in the procedure of construction of *** a result,the health conditions of REBs are evaluated by detecting the exhibited features in the *** and experiments are conducted to validate the effectiveness of the proposed method in terms of REB fault *** results demonstrate that the proposed method outperforms the current TFD algorithm and the conventional order tracking technique for fault diagnosis of REB under varying speed conditions.

关键词： Envelope analysis Fault diagnosis Order tracking Rolling element bearing Varying speed

Preparation of meter-scale Cu foils with decimeter grains and the use for the synthesis of graphene films

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Journal of Materiomics 2024年第1期10卷 1-6页

作者： Ruitao Jia Fangzhu Qing Shurong Wang Yuting Hou changqing shen Feng Hao Yang Yang Hongwei Zhu Xuesong Li School of Integrated Circuit Science and Engineering(Exemplary School of Microelectronics) University of Electronic Science and Technology of ChinaChengdu610054China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China shenzhen Institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen518110China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu610054China PipeChina Southwest Pipeline Co. Ltd.Chengdu610041China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Chemical vapor deposition(CVD)is the most promising method for the preparation of high-quality and large-area graphene films,especially the epitaxial growth of graphene on large-area single-crystal Cu *** single-crystal Cu foils are normally achieved by thermally annealing the commercial poly-crystalline Cu foils,their size and therefore the size of graphene films grown on them are limited to the size of the reaction *** report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils,where the Cu layers are separated by thin porous carbon fiber *** carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas *** such a way,the utilization efficiency of the reaction chamber is significantly improved,e.g.,0.2 m×(1e2)m Cu foils can be processed even in a 5 cm diameter quartz tube ***-quality graphene films grown on such Cu foils are then *** method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.

关键词： Graphene Single-crystal Cu Chemical vapor deposition Synthesis

Criteria for the growth of large-area adlayer-free monolayer graphene films by chemical vapor deposition

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Journal of Materiomics 2019年第3期5卷 463-470页

作者： changqing shen Xingzhou Yan Fangzhu Qing Xiaobin Niu Richard Stehle Samuel S.Mao Wanli Zhang Xuesong Li School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu610054China Department of Mechanical Engineering Sichuan University-Pittsburgh InstituteSichuan UniversityChengdu610207China Institute of New Energy Shenzhen518031China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA94720USA

Homogeneity is important to material applications for good performance of individual devices,for making AB-stacked bilayer graphene in a layer-by-layer stacking order,and from the point of view of industrial *** many properties to be controlled,for the case of graphene,the thickness(or layer number)uniformity is the *** vapor deposition(CVD)of C precursors on Cu substrates is the most popular method to produce large-area graphene *** date,precise control on the number of graphene layers as well as the uniformity over a large area is still very *** this work,with a further understanding of the factors affecting adlayer growth,the synthesis of large-area adlayer-free monolayer graphene(MLG)films was achieved up to tens of squared centimeters in area by just using untreated Cu foil and a normal CVD *** found that keeping equal C precursor concentration on the two sides of the Cu substrate is a criterion in addition to other factors such as the ratio of H:C and the substrate surface morphology for the growth of adlayer-free *** finding is not only of great significance for the industrial production of large-area adlayer-free MLG films but also instructive for the synthesis of homogeneous few-layer graphene.

关键词： Graphene Adlayer-free Chemical vapor deposition Monolayer Bilayer

A general and simple method for evaluating the electrical transport performance of graphene by the van der Pauw–Hall measurement

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Science Bulletin 2018年第22期63卷 1521-1526页

作者： Fangzhu Qing Yang Shu Linsen Qing Yuting Niu He Guo Shuyi Zhang Chunlin Liu changqing shen Wanli Zhang Samuel S.Mao Wenjuan Zhu Xuesong Li State Key Laboratory of Electronic Thin Films and Integrated Devices &School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Chengdu Institute of Biology Chinese Academy of SciencesChengdu 610041China National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of ChinaChengdu 610054China Institute of New Energy Shenzhen 518031China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA 94720USA Department of Electrical and Computer Engineering University of Illinois at Urbana-ChampaignUrbanaIL 61801USA

Expected for many promising applications in the field of electronics and optoelectronics, a reliable method for the characterization of graphene electrical transport properties is desired to predict its device performance or provide feedback for its ***, the commonly used methods of extracting carrier mobility from graphene field effect transistor or Hall-bar is time consuming, expensive, and significantly affected by the device fabrication process other than graphene *** we reported a general and simple method to evaluate the electrical transport performance of graphene by the van der Pauw–Hall *** annealing graphene in vacuum to remove the adsorbed dopants and then exposing it in ambient surroundings, carrier mobility as a function of density can be measured with the increase of carrier density due to the dopant re-adsorption from the ***, the relationship between the carrier mobility and density can be simply fitted with a power equation to the first level approximation, with which any pair of measured carrier mobility and density can be normalized to an arbitrary carrier density for *** experimentally demonstrated the reliability of the method, which is much simpler than making devices and may promote the standard making for graphene characterization.

关键词： Graphene Van der Pauw Hall Chemical vapor deposition (CVD)

A time domain correction method for Doppler-distortion signal from acoustic moving source

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Chinese Journal of Acoustics 2014年第1期33卷 32-41页

作者： LIU Fang HE Qingbo shen changqing HU Fei ZHANG Ao KONG Fanrang Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China

Doppler effect widely exists in the signal from the moving acoustic source. In order to solve such problems as frequency shift and frequency band expansion, a time domain cor- rection method is presented in this paper. First, the discrete time vector for interpolation and the amplitude restoration formula is derived based on the moving relationship and the Morse acoustic theory, then the amplitude weights are corrected and the distortion signal is interpolated. Every point of the discrete signal is operated separately in time domain. Compared with the existing frequency domain methods, this method does not need to know the characteristic frequency beforehand and would not be influenced by the blending of the frequency band. Hence, this method can be employed to correct multiple frequency signals and it is also a simple and effective Doppler effect reduction method.

关键词： time A time domain correction method for Doppler-distortion signal from acoustic moving source

Investigation on graphene growth by roll-to-roll chemical vapor deposition

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Science China Materials 2022年第4期65卷 1042-1048页

作者： Minghao Liang Ling-Xuan Qian Yuting Hou Jun Li changqing shen Fangzhu Qing Xuesong Li State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China shenzhen Institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen518110China

Both batch-to-batch(B2 B)and roll-to-roll(R2 R)processes can be used for mass production of graphene *** of the simplicity of equipment,the B2 B process is more commonly used in laboratory *** contrast,the R2 R process is more industrially preferred because it is easier to automate and more compatible with the subsequent transfer *** to now,the research on R2 R process has mainly focused on the design of the reactor or the loading configuration,but the in-depth understanding on the growth kinetics is *** this paper,we investigated the evolution of graphene growth and revealed that the graphene domain density grown by the R2 R process was larger than that by the B2 B process with the same reaction parameters,which was attributed to different reaction profiles between the two ***,the defective graphene could be healed with elongated reaction *** the optimized R2 R process,graphene films with quality comparable to those grown by conventional B2 B process could be *** research will promote the development of the mass-production technique for graphene films.

关键词： graphene chemical vapor deposition roll to roll kinetics

“信息园林”——构建新世纪信息化、人文化的景观大学城

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新建筑 2002年第4期 12-15页

作者：沈济黄叶长青浙江大学建筑设计研究院杭州310027

从对大学发展的简要回顾入手,探讨了大学校园在信息社会面临的各种建设问题,分析了新世纪大学校园规划与设计的发展趋势,并结合实例提出了创建新世纪“信息园林”为目标的大学校园规划与设计策略。

关键词：信息社会大学校园规划设计策略