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Dynamic analysis of spinning solar sails at deployment process

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Chinese Journal of Aeronautics 2017年第5期30卷 1719-1728页

作者： Xinxing zhang Chunyan zhou School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China

The spinning deployment process of solar sails is analyzed in this study. A simplified model is established by considering the out-of-plane and in-plane motions of solar sails. The influences of structure parameters, initial conditions, and feedback control parameters are also analyzed.A method to build the geometric model of a solar sail is presented by analyzing the folding process of solar sails. The finite element model of solar sails is then established, which contains continuous cables and sail membranes. The dynamics of the second-stage deployment of solar sails are simulated by using ABAQUS software. The influences of the rotational speed and out-of-plane movement of the hub are analyzed by different tip masses, initial velocities, and control *** with the results from theoretical models, simulation results show good agreements.

关键词： Deployment Dynamics Solar sail Spinning Stability

Decadal change of East Asian summer tropospheric temperature meridional gradient around the early 1990s

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Science China Earth Sciences 2015年第9期58卷 1609-1622页

作者： zhang LiXia zhou TianJun LASG Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Joint Center for Global Change Studies

During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper examines the decadal change of the East Asian summer tropospheric temperature around the early 1990 s. The results show that the meridional gradient of layer mean upper tropospheric temperature for 200–500 h Pa(here after UTT, UTT is upper tropospheric temperature) also underwent an obvious decadal decrease around 1992. The tropospheric temperature south to 35°N becomes decadal cooling, centered along the Yangtze River Valley, while the tropospheric temperature north to 35°N shows a decadal warming, centered in Northwest China-Mongolia. JRA-25 reanalysis is better than the other reanalysis datasets in revealing this decadal change. This decadal shift of East Asian summer UTT may be ascribed to the decadal change of the ENSO period from low-frequency oscillation(4–6 yr) to quasi-biennial oscillation since 1992. It behaves as an increase of ENSO developing events and a reduction of ENSO decaying events. It leads to stronger forcing of ENSO developing summer and weaker forcing of ENSO decaying summer, leading to the dominant role of monopole cooling mode of East Asian UTT after 1992, in contrast to the dominant role of dipole mode of East Asia UTT before 1992. The summer UTT difference between 1993–2004 and 1979–1992 shows a "South cooling-North Warming" pattern, and thereby contributes to the interdecadal decrease of East Asian summer UTT meridional gradient around 1992.

关键词： decadal variation around the early 1990s East Asian summer monsoon change of ENSO period

A vision-based navigation approach with multiple radial shape marks for indoor aircraft locating

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Chinese Journal of Aeronautics 2014年第1期27卷 76-84页

作者： zhou Haoyin zhang Tao Department of Automation School of Information Science and TechnologyTsinghua University National Key Laboratory of Integrated Flight Vehicle Control Technology Xi'an Flight Automatic Control Research Institute

Since GPS signals are unavailable for indoor navigation, current research mainly focuses on vision-based locating with a single mark. An obvious disadvantage with this approach is that locating will fail when the mark cannot be seen. The use of multiple marks can solve this problem. However, the extra process to design and identify different marks will significantly increase system complexity. In this paper, a novel vision-based locating method is proposed by using marks with feature points arranged in a radial shape. The feature points of the marks consist of inner points and outer points. The positions of the inner points are the same in all marks, while the positions of the outer points are different in different marks. Unlike traditional camera locating methods （the PnP methods）, the proposed method can calculate the camera location and the positions of the outer points simultaneously. Then the calculation results of the positions of the outer points are used to identify the mark. This method can make navigation with multiple marks more efficient. Simulations and real world experiments are carried out, and their results show that the proposed method is fast, accurate and robust to noise.

关键词： Flexible mark Indoor aircraft Multiple marks Navigation Vision-based locating

Investigation of UV–TiO_2 photocatalysis and its mechanism in Bacillus subtilis spore inactivation

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Journal of Environmental Sciences 2014年第9期26卷 1943-1948页

作者： Yiqing zhang Lingling zhou Yongji zhang Key Laboratory of Yangtze River Water Environment Ministry of EducationTongji University State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science & EngineeringTongji University

The inactivation levels of Bacillus subtilis spores for various disinfection processes （ultraviolet （UV）, TiO2 and UV-TiO2） were compared. The results showed that the inactivation effect of B. subtilis spores by UV treatment alone was far below that for bacteria without endospores. TiO2 alone in the dark, as a control experiment, exhibited almost no inactivation effect. Compared with UV treatment alone, the inactivation effect increased significantly with the addition of TiO2. Increases of the UV irradiance and Ti02 concentration both contributed to the increase of the inactivation effect. Lipid peroxidation was found to be the underlying mechanism of inactivation. Malondialdehyde （MDA）, the degradation product of lipid peroxidation, was used as an index to determine the extent of the reaction. The MDA concentration surged surprisingly to 3.24 nmol/mg dry cell with the combination disinfection for 600 see （0.10 mW/cm2 irradiance and 10 mg/L TiO2）. In contrast, for UV alone or TiO2 in the dark, the MDA concentration was 0.38 and 0.25 nmol/mg dry cell, respectively, under the same conditions. This indicated that both UV and TiO2 were essential for lipid peroxidation. Changes in cell ultrastructure were observed by transmission electron microscopy. The cell membrane was heavily damaged and cellular contents were completely lysed with the UV-TiO2 process, suggesting that lipid peroxidation was the root of the enhancement in inactivation efficiency.

关键词： UVTi02Bacillus subfilis sporesDisinfectionLipid peroxidation

Double Hopf bifurcation of composite laminated piezoelectric plate subjected to external and internal excitations

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Applied Mathematics and Mechanics(English Edition) 2017年第5期38卷 689-706页

作者： Yan zhou Wei zhang Mathematics Science College Inner Mongolia Normal University Beijing Key Laboratory on Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of Technology

The double Hopf bifurcation of a composite laminated piezoelectric plate with combined external and internal excitations is studied. Using a multiple scale method, the average equations are obtained in two coordinates. The bifurcation response equations of the composite laminated piezoelectric plate with the primary parameter resonance, i.e., 1：3 internal resonance, are achieved. Then, the bifurcation feature of bifurcation equations is considered using the singularity theory. A bifurcation diagram is obtained on the parameter plane. Different steady state solutions of the average equations are analyzed. By numerical simulation, periodic vibration and quasi-periodic vibration responses of the Composite laminated piezoelectric plate are obtained.

关键词： double Hopf bifurcation composite laminated piezoelectric plate periodic solution quasi-periodic solution

MODIFICATION OF ONE-DIMENSION COUPLED HYSTERESIS MODEL FOR GMM WITH THE DOMAIN FLEXING FUNCTION

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Acta Mechanica Solida Sinica 2014年第5期27卷 461-466页

作者： Yongfei zhang Youhe zhou Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China Lanzhou University Department of Mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

This paper focuses on eliminating the unphysical negative susceptibility which ap- pears when magnetic field is at unsaturated excitation level and reduces from extremity of the hysteresis loop in one-dimension coupled hysteresis model. The domain flexing function c （H） is used to replace the domain flexing constant c in one-dimension coupled hysteresis model. The fea- sibility and rationality of proposed modification are convinced by comparing the magnetization and magnetostriction curves with experimental data and another typical modification results. The effects of pre-stress and temperature on magnetic-elastic-thermal coupling property and hysteresis behavior are investigated.

关键词： coupled hysteresis model domain flexing function negative susceptibility innerloop

Study on cracking of welding overlay based on the theory of diffusion-induced stress

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Acta Metallurgica Sinica(English Letters) 2011年第1期24卷 75-80页

作者： Xiliang zhang Changyu zhou School of Mechanical and Power Engineering Nanjing University of Technology Nanjing 210009 China

Hydrogen diffusion in the wall of hydrogenation reactor for three situations, i.e. operating, normal shutdown and abnormal shutdown, was numerically simulated based on the finite element program-ABAQUS. The formula of diffusion-induced stress was deduced for model of the thin walled cylinder. Distribution of diffusion-induced stress in the wall of hydrogenation reactor was studied. The results showed that the maximum stress was at the fusion surface between welding overlay and base metal and which would increase with cooling rate. The crack will initiate and propagate from fusion surface to welding overlay when the diffusion-induced stress is higher than yield stress, but it will not propagate to the base metal. Diffusion-induced stress is one of the important factors for crack initiation and propagation of welding overlay of hydrogenation reactor.

关键词： Diffusion-induced stress Hydrogen diffusion Welding overlay Crack initiation ABAQUS

Developing a Physiological Signal-Based, Mean Threshold and Decision-Level Fusion Algorithm (PMD) for Emotion Recognition

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Tsinghua Science and Technology 2023年第4期28卷 673-685页

作者： Qiuju zhang Hongtao zhang Keming zhou Le zhang College of Computer Science Sichuan UniversityChengdu 610065China August International Ltd. HoddesdonEN110EEUK Key Laboratory of Systems Health Science of Zhejiang Province Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China

With the development of computers,artificial intelligence,and cognitive science,engagement in deep communication between humans and computers has become increasingly ***,affective computing is a current hot research ***,this study constructs a Physiological signal-based,Mean-threshold,and Decision-level fusion algorithm(PMD)to identify human emotional ***,we select key features from electroencephalogram and peripheral physiological signals,and use the mean-value method to obtain the classification threshold of each participant and distinguish individual ***,we employ Gaussian Naive Bayes(GNB),Linear Regression(LR),Support Vector Machine(SVM),and other classification methods to perform emotion ***,we improve the classification accuracy by developing an ensemble *** experimental results reveal that physiological signals are more suitable for emotion recognition than classical facial and speech *** proposed mean-threshold method can solve the problem of individual differences to a certain extent,and the ensemble learning model we developed significantly outperforms other classification models,such as GNB and LR.

关键词： electroencephalogram(EEG) peripheral physiological signals machine learning emotion recognition multimodal fusion

Shock resistance of supercharged boilers through integration with ship structure

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Journal of Marine Science and Application 2007年第4期6卷 18-26页

作者： YAO Xiong-liang FENG Lin-han zhang A-man zhou Qi-xin College of Shipbuilding Engineering Harbin Engineering University Harbin 150001 China

The non-linear finite element software ABAQUS was used to simulate the dynamic response of a marine supercharged boiler when subjected to impact loading. Shock resistance was analyzed by the time-domain simulation method. After exhaustive simulations,the effect of air pressure induced by different working conditions on the shock response of a supercharged boiler was reviewed,leading to conclusions about the variability of structural response with different loading parameters. In order to simulate the real impulsive environments of supercharged boilers,the integration of equipment and ship structure was then primarily used to analyze shock response. These distinctly different equipment shock test methods,run under equivalent work conditions,were compared and the causes of discrepancy were analyzed. The main purpose of this paper is to present references for the anti-shock design of marine supercharged boilers.

关键词： supercharged boiler numerical simulation dynamic response shock resistance integrationof equipment and ship structure