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Grey Relation between Nonlinear Characteristic and Dynamic Uncertainty of Rolling Bearing Friction Torque

Chinese Journal of Mechanical Engineering 2009年第2期22卷 244-249页

作者： XIA Xintao wang zhongyu College of Mechatronical Engineering Henan University of Science and Technology Luoyang 4 71003 China College of Instrumental Science and Optoelectronics Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

The rolling bearing friction torque which is characterized by its uncertainty and nonlinearity affects heavily the dynamic performance of a system such as missiles, spacecrafts and radars, etc. It is difficult to use the classical statistical theory to evaluate the dynamic evaluation of the rolling bearing friction torque for the lack of prior information about both probability distribution and trends. For this reason, based on the information poor system theory and combined with the correlation dimension in chaos theory, the concepts about the mean of the dynamic fluctuant range （MDFR） and the grey relation are proposed to resolve the problem about evaluating the nonlinear characteristic and the dynamic uncertainty of the rolling bearing friction torque. Friction torque experiments are done for three types of the rolling bearings marked with HKTA, HKTB and HKTC separately; meantime, the correlation dimension and MDFR are calculated to describe the nonlinear characteristic and the dynamic uncertainty of the friction torque, respectively. And the experiments reveal that there is a certain grey relation between the nonlinear characteristic and the dynamic uncertainty of the rolling bearing friction torque, viz. MDFR will become the nonlinear increasing trend with the correlation dimension increasing. Under the condition of fewer characteristic data and the lack of prior information about both probability distribution and trends, the unitive evaluation for the nonlinear characteristic and the dynamic uncertainty of the rolling bearing friction torque is realized with the grey confidence level of 87.7%-96.3%.

关键词： rolling bearing friction torque time series correlation dimension mean of dynamic fluctuant range (MDFR),information poor system theory

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DNA-based nanosystems to generate reactive oxygen species for nanomedicine

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Chinese Chemical Letters 2024年第11期35卷 25-34页

作者： zhongyu wang Lijun wang Huaixin Zhao Frontiers Science Center for Synthetic Biology Key Laboratory of Systems Bioengineering(MOE)Institute of Biomolecular and Biomedical EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China

Reactive oxygen species(ROS)are essential in various pathological and physiological *** nanosystems that generate ROS in a controlled manner is of great interest for *** nanotechnology offers a promising approach to constructing programmable ROS-generating *** incorporating photosensitizers or metal ions,DNA nanostructures can be designed to produce ROS in a spatially and temporally desired ***-based ROS-generating nanosystems hold great potential in intracellular homeostasis regulation,drug release,and cancer *** review summarizes recent advances in developing DNA-based ROS-generating nanosystems,highlights their emerging biomedical applications,and discusses the opportunities and challenges for further *** nanotechnology provides a versatile toolkit to construct biocompatible ROS-generating platforms for next-generation nanomedicines.

关键词： DNA nanotechnology Photodynamic therapy Chemodynamic therapy Reactive oxygen species Nanomedicine

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Fuzzy norm method for evaluating random vibration of airborne platform from limited PSD data

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Chinese Journal of Aeronautics 2014年第6期27卷 1442-1450页

作者： wang zhongyu wang Yanqing wang Qian Zhang Jianjun School of Instrumentation Science & Opto-electronics Engineering Beihang University College of Electronic Communication and Physics Shandong University of Science and Technology Center of Quality Engineering of China Aero-Polytechnology Establishment

For random vibration of airborne platform, the accurate evaluation is a key indicator to ensure normal operation of airborne equipment in flight. However, only limited power spectral density（PSD） data can be obtained at the stage of flight test. Thus, those conventional evaluation methods cannot be employed when the distribution characteristics and priori information are unknown. In this paper, the fuzzy norm method（FNM） is proposed which combines the advantages of fuzzy theory and norm theory. The proposed method can deeply dig system information from limited data, which probability distribution is not taken into account. Firstly, the FNM is employed to evaluate variable interval and expanded uncertainty from limited PSD data, and the performance of FNM is demonstrated by confidence level, reliability and computing accuracy of expanded uncertainty. In addition, the optimal fuzzy parameters are discussed to meet the requirements of aviation standards and metrological practice. Finally, computer simulation is used to prove the adaptability of FNM. Compared with statistical methods, FNM has superiority for evaluating expanded uncertainty from limited data. The results show that the reliability of calculation and evaluation is superior to 95%.

关键词： Expanded uncertainty Fuzzy norm method Limited PSD data Random vibration Reliability Variable interval

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Dynamically Adapt to Uneven Terrain Walking Control for Humanoid Robot

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 214-222页

作者： WEI Hui SHUAI Mei wang zhongyu School of Instrumentation Science and Opto-electronics Engineering Beihang UniversityBeijing 100191China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Dynamically adapt to uneven ground locomotion is a crucial ability for humanoid robots utilized in human ***,because of the effect of current pattern generation method,adapting to unknown rough ground is ***,to maintain large support region by four-point contact during the landing phase is usually a key *** order to solve these problems,a landing phase control and online pattern generation in three dimensional environments is *** the basis of robot-environment non-planar interactive modes,a method of landing control based on optimal support region is put forward to realize stable four-point contact by flexible foot,and a controller is employed to adapt to the changes of ground without using prior ***,an adaptable foothold planning is put forward to the online pattern generation considering walking speed,uneven terrain,and the effect of lateral movement to the locomotion ***,the effectiveness of landing control and online pattern generation is demonstrated by dynamic simulations and real robot walking experiments on outdoor uneven *** results indicate that the robot kept its balance even though the ground is unknown and *** proposed methods lay a foundation for studies of humanoid robots performing tasks in complex environments.

关键词： humanoid robots landing control online gait generation uneven terrain

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Oxidation reactivity of 1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE)by CompoundⅠmodel of cytochrome P450s

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Journal of Environmental Sciences 2017年第12期29卷 11-21页

作者： zhongyu wang Zhiqiang Fu Qi Yu Jingwen Chen Key Laboratory of Industrial Ecology and Environmental Engineering(MOE) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China

Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is *** have previously proved that density functional theory（DFT） is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis（2,4,6-tribromophenoxy）ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis（2,4,6-tribromophenoxy）ethanol, which may undergo hydrolysis yielding2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.

关键词： 1 2-Bis(2 4 6-tribromophenoxy)ethane(BTBPE) Alternative brominated flame retardants Metabolic reactivity P450 Compound Ⅰ

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Gray bootstrap method for estimating frequency-varying random vibration signals with small samples

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Chinese Journal of Aeronautics 2014年第2期27卷 383-389页

作者： wang Yanqing wang zhongyu Sun Jianyong Zhang Jianjun Zissimos Mourelato School of Instrumentation Science & Opto-electronics Engineering Beihang University College of Science Shandong University of Science and Technology The Comprehensive Technology Research Institute of China Aviation Mechanical Engineering Department Oakland University

During environment testing, the estimation of random vibration signals （RVS） is an important technique for the airborne platform safety and reliability. However, the available meth- ods including extreme value envelope method （EVEM）, statistical tolerances method （STM） and improved statistical tolerance method （ISTM） require large samples and typical probability distri- bution. Moreover, the frequency-varying characteristic of RVS is usually not taken into account. Gray bootstrap method （GBM） is proposed to solve the problem of estimating frequency-varying RVS with small samples. Firstly, the estimated indexes are obtained including the estimated inter- val, the estimated uncertainty, the estimated value, the estimated error and estimated reliability. In addition, GBM is applied to estimating the single flight testing of certain aircraft. At last, in order to evaluate the estimated performance, GBM is compared with bootstrap method （BM） and gray method （GM） in testing analysis. The result shows that GBM has superiority for estimating dynamic signals with small samples and estimated reliability is proved to be 100% at the given confidence level.

关键词： Dynamic process Estimation Frequency-varying Gray bootstrap method Random vibration signalsSmall samples

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Novel Flexible Foot System for Humanoid Robot Adaptable to Uneven Ground

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Chinese Journal of Mechanical Engineering 2010年第6期23卷 725-732页

作者： WEI Hui SHUAI Mei wang zhongyu ZHANG Chuanyou LI Li School of Instrumentation Science and Opto-electronics Engineering Beihang University Beijing 100191 China School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Zhejiang New Jack Sewing Machine Co Ltd Taizhou 318010 China

Humanoid robots can walk stably on flat ground, regular slopes, and stairs. However, because of their rigid and flat soles, adapting to unknown rough terrains is limited, moreover, to maintain large scale four-point contact for foot structures to keep balance is usually a key technical problem. In order to solve these problems, the control strategy and foot structures should be improved. In this paper, a novel flexible foot system is proposed. This system occupies 8 degrees of freedom （DOF）, and can obtain larger support region to keep in four-point contact with uneven terrains; Novel cable transmission technology is put forward to reduce complexity of traditional mechanism and control strategy, and variation of each DOF is mapped to cable displacement. Furthermore, kinematics of this new system and a global dynamic model based on contact-force feedback are analyzed. According to stability criterion and feedback sensor information, a method calculating the optimal attitude matrix of contact points and joint variables is introduced. Virtual prototyping models of a 30-DOF humanoid robot and rough terrain are established to simulate humanoid robot walking on uneven ground, and feasibility of this system adapted to uneven terrain and validity of its control strategy are verified. The proposed research enhances the capability of humanoid robots to adapt to large scale uneven ground, expands the application field of humanoid robots, and thus lays a foundation for studies of humanoid robots performing tasks in complex environments in place of humans.

关键词： humanoid robots flexible foot contact force feedback uneven ground

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Cycle-by-Cycle Queue Length Estimation for Signalized Intersections Using Multi-Source Data

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Journal of Harbin Institute of Technology(New Series) 2015年第2期22卷 86-93页

作者： zhongyu wang Qing Cai Bing Wu Yinhai wang Linbo Li Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji University Dept. of Civil and Environmental Engineering University of Washington

In order to estimate vehicular queue length at signalized intersections accurately and overcome the shortcomings and restrictions of existing studies especially those based on shockwave theory,a new methodology is presented for estimating vehicular queue length using data from both point detectors and probe vehicles. The methodology applies the shockwave theory to model queue evolution over time and space. Using probe vehicle locations and times as well as point detector measured traffic states,analytical formulations for calculating the maximum and minimum( residual) queue length are developed. The proposed methodology is verified using ground truth data collected from numerical experiments conducted in Shanghai,China. It is found that the methodology has a mean absolute percentage error of 17. 09%,which is reasonably effective in estimating the queue length at traffic signalized intersections. Limitations of the proposed models and algorithms are also discussed in the paper.

关键词： queue length estimation multi-source data traffic signals traffic shockwave theory

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Femtosecond laser-acoustic modeling and simulation for AlCu nanofilm nondestructive testing

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Frontiers of Mechanical Engineering 2024年第5期19卷 59-71页

作者： zhongyu wang Jing MIN Jing HU Zehan wang Xiuguo CHEN Zirong TANG Shiyuan LIU State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Optics Valley Laboratory Wuhan 430074China

Photoacoustic detection has shown excellent performance in measuring thickness and detecting defects in metal ***,existing research on ultrafast lasers mainly focuses on using picosecond or nanosecond lasers for large-scale material processing and *** theoretical study of femtosecond laser sources for photoacoustic nondestructive testing(NDT)in nanoscale thin film materials receives much less emphasis,leading to a lack of a complete physical model that covers the entire process from excitation to *** this study,we developed a comprehensive physical model that combines the two-temperature model with the acoustic wave generation and detection *** the basis of the physical model,we established a simulation model to visualize the ultrafast lasermaterial interaction *** damage threshold of the laser source is determined,and the effect of key parameters(laser fluence,pulse duration,and wavelength)for AlCu nanofilms on the femtosecond photoacoustic NDT process is discussed using numerical results from the finite element *** numerical results under certain parameters show good agreement with the experimental results.

关键词： femtosecond photoacoustic nondestructive testing metal nanofilm ultrafast laser-matter interaction modeling and simulation semiconductor manufacturing

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Occurrence and Removal of Antibiotic Resistance in Nationwide Hospital Wastewater Deciphered by Metagenomics Approach-China,2018-2022

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China CDC weekly 2023年第46期5卷 1023-1028,I0001-I0004页

作者： Jin Huang zhongyu wang Zihan Chen Hebin Liang Xiaoyan Li Bing Li State Environmental Protection Key Laboratory of Microorganism Application and Risk Control Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen CityGuangdong ProvinceChina Shenzhen Environmental Science and New Energy Laboratory Tsinghua-Berkeley Shenzhen InstituteTsinghua UniversityShenzhen CityGuangdong ProvinceChina

Summary What is already known about this topic?Hospital wastewater represents a significant conduit for the dissemination of antibiotic resistance genes(ARGs),including those that are of clinical ***,the variation in antibiotic resistance on a national level,which can be influenced by regional differences,has not been thoroughly elucidated.

关键词： wastewater Wastewater thoroughly

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