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Noise-Tolerant ZNN-Based Data-Driven Iterative Learning Control for Discrete Nonaffine Nonlinear MIMO Repetitive Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 344-361页

作者： yunfeng hu Chong Zhang Bo Wang Jing Zhao Xun Gong Jinwu Gao Hong Chen State Key Laboratory of Automotive Simulation and Control Jilin UniversityJilin UniversityChangchun 130025China College of Communication Engineering Jilin UniversityJilin UniversityChangchun 130025China Department of Electromechanical Engineering University of MacaoMacao 999078China School of Artificial Intelligence Jilin UniversityChangchun 130012China IEEE College of Electronics and Information Engineering Tongji UniversityShanghai 200092China

Aiming at the tracking problem of a class of discrete nonaffine nonlinear multi-input multi-output(MIMO) repetitive systems subjected to separable and nonseparable disturbances, a novel data-driven iterative learning control(ILC) scheme based on the zeroing neural networks(ZNNs) is proposed. First, the equivalent dynamic linearization data model is obtained by means of dynamic linearization technology, which exists theoretically in the iteration domain. Then, the iterative extended state observer(IESO) is developed to estimate the disturbance and the coupling between systems, and the decoupled dynamic linearization model is obtained for the purpose of controller synthesis. To solve the zero-seeking tracking problem with inherent tolerance of noise,an ILC based on noise-tolerant modified ZNN is proposed. The strict assumptions imposed on the initialization conditions of each iteration in the existing ILC methods can be absolutely removed with our method. In addition, theoretical analysis indicates that the modified ZNN can converge to the exact solution of the zero-seeking tracking problem. Finally, a generalized example and an application-oriented example are presented to verify the effectiveness and superiority of the proposed process.

关键词： Adaptive control control system synthesis data-driven iterative learning control neurocontroller nonlinear discrete time systems

Damage evolution and removal behaviors of GaN crystals involved in double-grits grinding

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International Journal of Extreme Manufacturing 2024年第2期6卷 469-484页

作者： Chen Li Yuxiu hu Zongze Wei Chongjun Wu yunfeng Peng Feihu Zhang Yanquan Geng State Key Laboratory of Robotics and System(HIT) Harbin Institute of TechnologyHarbin 150001People’s Republic of China Key Laboratory of Microsystems and Microstructures Manufacturing(HIT) Harbin Institute of TechnologyHarbin 150001People’s Republic of China College of Mechanical Engineering Donghua UniversityShanghai 201620People’s Republic of China Department of Mechanical and Electrical Engineering Xiamen UniversityXiamen 361005People’s Republic of China

Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.***.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.

关键词： grinding double-grits molecular dynamics damage material removal gallium nitride

Modeling and prediction of tribological properties of copper/aluminum-graphite self-lubricating composites using machine learning algorithms

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Friction 2024年第6期12卷 1322-1340页

作者： huifeng NING Faqiang CHEN yunfeng SU Hongbin LI Hengzhong FAN Junjie SONG Yongsheng ZHANG Litian hu School of Electrical and Mechanical Engineering Lanzhou University of TechnologyLanzhou 730050China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

The tribological properties of self-lubricating composites are influenced by many variables and complex mechanisms.Data-driven methods,including machine learning(ML)algorithms,can yield a better comprehensive understanding of complex problems under the influence of multiple parameters,typically for how tribological performances and material properties correlate.Correlation of friction coefficients and wear rates of copper/aluminum-graphite(Cu/Al-graphite)self-lubricating composites with their inherent material properties(composition,lubricant content,particle size,processing process,and interfacial bonding strength)and the variables related to the testing method(normal load,sliding speed,and sliding distance)were analyzed using traditional approaches,followed by modeling and prediction of tribological properties through five different ML algorithms,namely support vector machine(SVM),K-Nearest neighbor(KNN),random forest(RF),eXtreme gradient boosting(XGBoost),and least-squares boosting(LSBoost),based on the tribology experimental data.Results demonstrated that ML models could satisfactorily predict friction coefficient and wear rate from the material properties and testing method variables data.Herein,the LSBoost model based on the integrated learning algorithm presented the best prediction performance for friction coefficients and wear rates,with R2 of 0.9219 and 0.9243,respectively.Feature importance analysis also revealed that the content of graphite and the hardness of the matrix have the greatest influence on the friction coefficients,and the normal load,the content of graphite,and the hardness of the matrix influence the wear rates the most.

关键词： self-lubricating composites machine learning(ML) tribological properties prediction

Improvement effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)on hydrogen storage performance of MgH_(2)

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Journal of Magnesium and Alloys 2024年第1期12卷 197-208页

作者： Yingyan Zhao Zhibing Liu Jiangchuan Liu yunfeng Zhu Jiguang Zhang Yana Liu Xiaohui hu Liquan Li College of Materials Science and Engineering Nanjing Tech University30 South Puzhu RoadNanjing211816PR China Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites Nanjing Tech UniversityNanjing211816PR China

The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.

关键词： Magnesium hydride Reversible solid solution Core-shell nanoparticles Hydrogen storage performance

Research Progress on the Association between Schizophrenia and Toxoplasma gondii Infection

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Biomedical and Environmental Sciences 2024年第6期37卷 647-660页

作者： Yiting Zhu Xiaohui Yang Miaoru Chen Yu hu yunfeng Chang Xiang Wu Department of Forensic Medicine Science Xiangya School of Basic MedicineCentral South UniversityChangsha 410013HunanChina Nursing Department The Third Xiangya Hospital of Central South UniversityChangsha 410013HunanChina Department of Basic Medicine Science Xiangya School of Basic MedicineCentral South UniversityChangsha 410013HunanChina Department of Parasitology Xiangya School of Basic MedicineCentral South UniversityChangsha 410013HunanChina

Toxoplasma gondii(T.gondii or Tg),is an obligatory intracellular parasite with humans as its intermediate hosts.In recent years,significant correlations between T.gondii infection and schizophrenia have been reported,including the possible mediating mechanisms.Currently,mechanisms and hypotheses focus on central neurotransmitters,immunity,neuroinflammation,and epigenetics;however,the exact underlying mechanisms remain unclear.In this article,we review the studies related to T.gondii infection and schizophrenia,particularly the latest research progress.Research on dopamine(DA)and other neurotransmitters,the blood-brain barrier,inflammatory factors,disease heterogeneity,and other confounders is also discussed.In addition,we also summarized the results of some new epidemiological investigations.

关键词： Toxoplasma gondii Schizophrenia Neurotransmitters Neuroinflammation Immunity Epigenetics

Regional Differences of China′s Urban Expansion from Late 20th to Early 21st Century Based on Remote Sensing Information

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Chinese Geographical Science 2012年第1期22卷 1-14页

作者： LIU Jiyuan ZHANG Qian hu yunfeng Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Department of Urban Planning and Environment KTH-Royal Institute of Technology Stockholm 10044 Sweden

This study investigated the regional differences of China′s urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China′s land cover/land use database) datasets which were mainly produced from remote sensing imagery data. A newly defined urbanization level index (UI), based on urban land area, is proposed to describe Chinese urban expansion process at 1 kilometer, provincial, regional, and na-tional scales, together with the absolute urban expansion index (UEa) and the relative urbanization expansion index (UEr). The results indicate that the percentages of total land area occupied by urban in the late 1980s, 1995, 2000, 2005, and 2008 were approximately 0.25%, 0.32%, 0.33%, 0.43% and 0.52% of China′s total land area, respectively. Between the late 1980s and 2008, the total urban expansion in the mainland of China was 2.645 × 104 km2, resulting in an annual urban expansion area of about 1322.7 km2/yr, with the UEr of 111.9%. This study also finds that there has been an obvious spatial gradient of urbanization ratio running from the east coast to the west inland, and the urbanization gaps among different regions have persisted over the past two decades. The study also reveals obvious temporal varia-tions of the urbanization rates. There was very little urban growth during the period of 1995-2000 due to the governmental policy factors.

关键词：中国内地城市扩展区域差异遥感信息后期城市化水平土地利用数据库基础

Utilization of One Novel Microbial Esterase WDEst9 in the Kinetic Resolution of (5)-Methyl 2-chloropropionate and (5)-Ethyl 2-chloropropionate

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Chemical Research in Chinese Universities 2019年第5期35卷 830-836页

作者： WANG Yilong XU Yongkai ZHANG Yun SUN Aijun hu yunfeng CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301P.R.China Guangdong Key Laboratory of Marine Materia Medica South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301P.R.China Affiliated Hospital of Shandong University of Traditional Chinese Medicine Jinan 250014P.R.China

One novel microbial esterase WDEst9 from Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085 was functionally characterized and the results demonstrated that the enantio-preference of WDEst9 was opposite to that of three other microbial esterases(BSE01701, PHE14 and Bae02030) in the kinetic resolution of racemic methyl lactate. We further investigated the potential of esterase WDEst9 in the kinetic resolution of both (±)-methyl 2-chloropropionate and (±)-ethyl 2-chioropropionate. The enantio-preference of WDEst9 was also interestingly opposite to that of esterases EST 12-7 and EstC10, and generated (S)-methyl 2-chloropropionate and (S)-ethyl 2-chloropropionate with high enantiomeric excess(both e.e.>98%) and high yield after many iterations of process optimization. Through genome mining, microbial esterase WDEst9 was characterized to be a novel esterase which may provide valuable complementary enantio-selectivity and possesses very good potential in the kinetic resolution of high value-added chiral chemicals.

关键词： Biocatalysis Novel esterase Asymmetric hydrolysis Complementary enantio-preference (5)-Methyl 2-chloropropionate (S)-Ethyl 2-chloropropionate

Modeling the radiation balance of different urban underlying surfaces

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Chinese Science Bulletin 2012年第9期57卷 1046-1054页

作者： CUI YaoPing LIU JiYuan hu yunfeng WANG JunBang KUANG Wenhui Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

An urban net all-wave radiation parameterization scheme is evaluated using annual datasets for 2010 recorded at a Beijing urban observation site.The statistical relationship between observed data and simulation data of net radiation has a correlation coefficient of 0.98 and model efficiency of 0.93.Therefore,it can be used to simulate the radiation balance of Beijing.This study analyzes the variation in the radiation balance for different underlying surfaces.To simulate radiation balance differences,we set four pure land-cover types(forest,grass,roads,and buildings).Keeping all other conditions inputted unchanged,we model the radiation balance by changing the land-cover type.The results show that the effects of different underlying surfaces on radiation differ,and that there is much upward long-wave radiation,accounting for 84.3% of the total radiation energy falling incident on the land surface.The annual averages of net radiation for the four land-cover types are in the range of 38.2-53.4 W/m2.The net radiation of the grass surface is minimal while that of the roads surface is maximal.Additionally,with urbanization the net radiation values of common types of land-cover change,such as conversion from forest to roads,grass to roads,and grass to buildings,all have increasing trends,indicating that net radiation usually increases with urban sprawl.

关键词：辐射平衡城市化下垫面土地覆盖类型建模模拟数据平衡模型参数化方案

Using ^(137)Cs tracing technique to estimate wind erosion rates in the typical steppe region, northern Mongolian Plateau

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Chinese Science Bulletin 2008年第9期53卷 1423-1430页

作者： QI YongQing LIU JiYuan SHI huaDing hu yunfeng ZhuANG DaFang Institute of Geographic Sciences and Resources Research Chinese Academy of Sciences Beijing 100101 China Chinese Research Academy of Environmental Sciences Beijing 100012 China

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.

关键词：蒙古高原北部草原风蚀铯元素跟踪技术