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A Markov Model for Subway Composite Energy Prediction

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Computer Systems Science & Engineering 2021年第11期39卷 237-250页

作者： Xiaokan wang Qiong wang Liang Shuang Chao Chen Henan Mechanical and Electrical Vocational College Xinzheng451191China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing100044China University of Florence Firenze50041Italy

Electric vehicles such as trains must match their electric power supply and demand,such as by using a composite energy storage system composed of lithium batteries and *** this paper,a predictive control strategy based on a Markov model is proposed for a composite energy storage system in an urban rail *** model predicts the state of the train and a dynamic programming algorithm is employed to solve the optimization problem in a forecast time ***-time online control of power allocation in the composite energy storage system can be *** standard train operating conditions for simulation,we found that the proposed control strategy achieves a suitable match between power supply and demand when the train is *** with traditional predictive control systems,energy efficiency 10.5%*** system provides good stability and robustness,satisfactory speed tracking performance and control comfort,and significant suppression of disturbances,making it feasible for practical applications.

关键词： Markov model predictive control composite energy storage urban rail train

Precipitation changes in the mid-latitudes of the Chinese mainland during 1960–2014

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Journal of Arid Land 2017年第6期9卷 924-937页

作者： HU Yuling wang Shigong SONG Xuping wang Jiaxin Key laboratory of Arid Climate Change and Reducing Disaster in Gansu Province College of Atmospheric Sciences Lanzhou University Plateau Environment and Meteorology Key Laboratory of Education Bureau of Sichuan Province College of Atmospheric Sciences Chengdu University of Information Technology

Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland（MCM） during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall *** to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM. The western MCM was further divided into the western MCM1 and western MCM2 in terms of the effects of the East Asian summer monsoon. The main results were as follows：（1） During the last four decades of the 20^（th） century, the area-averaged annual precipitation presented a significant increasing trend in the western MCM, but there was a slight decreasing trend in the eastern MCM, where a seesaw pattern was apparent. However, in the 21^（st） century, the area-averaged annual precipitation displayed a significant increasing trend in both the western and eastern MCM.（2） The trend in area-averaged seasonal precipitation during 1960–2014 in the western MCM was consistent with that in the eastern MCM in winter and spring. However, the trend in area-averaged summer precipitation during1960–2014 displayed a seesaw pattern between the western and eastern MCM.（3） On an annual basis,both the trend in rainstorms and heavy rain displayed a seesaw pattern between the western and eastern MCM.（4） The precipitation intensity in rainstorms, heavy rain, and moderate rain made a greater contribution to changes in the total precipitation than precipitation frequency. The results of this study will improve our understanding of the trends and differences in precipitation changes in different areas of the MCM. This is not only useful for the management and mitigation of flood disasters, but is also beneficial to the protection of water resources across the MCM.

关键词： precipitation changes the mid-latitudes of the Chinese mainland seesaw pattern rainy days precipitation intensity precipitation frequency

Early Holocene environment at a key location of the northwest boundary of the Asian summer monsoon: a synthesis on chronologies of Zhuye Lake, Northwest China

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Journal of Arid Land 2014年第5期6卷 511-528页

作者： Yu LI NaiAng wang ChengQi ZHANG Yue wang Center for Hydrologic Cycle and Water Resources in Arid Region College of Earth and Environmental Sciences Lanzhou University

The intensified monsoon increases summer rainfall and creates wet conditions in the Asian summer monsoon region during the early Holocene. Along with millennial-scale changes of the monsoon intensity, it is still unclear whether the boundary of the monsoon region changes according to monsoon variability. Investigations into the early Holocene environment in monsoon marginal zones are crucial for understanding the monsoon boundary changes. Zhuye Lake is located at the northwest edge of the Asian summer monsoon, the northern Qilian Mountains, which are less affected by modern summer monsoon water vapor. Previous studies have reached different conclusions regarding the early Holocene climatic and environmental changes based on different dating methods（^14C and OSL（optically stimulated luminescence）） and materials（shells, carbonate, pollen concentrates and bulk organic carbon）. In this study, we synthesized 102 ^14C dates and 35 OSL dates from ten Holocene sedimentary sections and ten paleo-shorelines in the lake basin. A comparison between ages from different dating methods and materials generally shows that carbon reservoir effects are relatively slight in Zhuye Lake while the disordered chronologies are mainly related to the erosion processes and reworking effects. In addition, proxy data, including lithology, pollen, total organic carbon and carbonate, were collected from different sites of Zhuye Lake. According to the new synthesis, the early Holocene environment was relatively humid, associated with high runoff and lake water levels. The result indicates that the monsoon boundary moves to the north during the period of the intensified monsoon. A typical arid-area lake was formed during the mid-Holocene when carbonate accumulation and high organic matter contents were the main features of this period. The lake retreated strongly during the late Holocene, showing a drought trend. Overall, the lake evolution is generally consistent with the Holocene Asian summer mons

关键词： the early Holocene ^14C dating OSL dating lacustrine sediments Asian summer monsoon monsoon marginal zones

Improved statistical sparse decomposition principle method for underdetermined blind source signal recovery

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The Journal of China Universities of Posts and Telecommunications 2019年第6期26卷 94-102页

作者： wang Chuanchuan Zeng Yonghu wang Liandong Fu Weihong State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang 471003China State Key Laboratory of Integrated Services Networks Xidian UniversityXi'an 710071China

Aiming at the statistical sparse decomposition principle(SSDP) method for underdetermined blind source signal recovery with problem of requiring the number of active signals equal to that of the observed signals, which leading to the application bound of SSDP is very finite, an improved SSDP(ISSDP) method is proposed. Based on the principle of recovering the source signals by minimizing the correlation coefficients within a fixed time interval, the selection method of mixing matrix’s column vectors used for signal recovery is modified, which enables the choose of mixing matrix’s column vectors according to the number of active source signals self-adaptively. By simulation experiments, the proposed method is validated. The proposed method is applicable to the case where the number of active signals is equal to or less than that of observed signals, which is a new way for underdetermined blind source signal recovery.

关键词： underdetermined blind source separation signal recovery ISSDP

Influence of control strategy on stability of dual-spin projectiles with fixed canards

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Defence Technology（防务技术） 2018年第6期14卷 709-719页

作者： Yu wang Xiao-ming wang Ji-yan Yu Nanjing University of Science & Technology School of Mechanical Engineering

Existing literature has shown that the control force at the nose could cause dynamic instability for controlled projectiles. To lower the adverse impact on the dual-spin projectile with fixed canards under the premise of meeting guidance system requirements, the influence of control moment provided by a motor on the flight stability is analyzed in this paper. Firstly, the effect of the rolling movement on stability is analyzed based on the stability criterion derived using the Hurwitz stability theory. Secondly, the evaluation parameters combining the features of different control periods that could assess the variation of stability features after the motor torque are obtained. These effective formulas are used to indicate that, to reduce the flight instability risks, the stabilized rolling speed of roll speed keeping period should be as small as possible; the variation trend of motor torque during the rolling speed controlling period and the roll angle of the forward body during roll angle switching period are recommended corresponding to the projectile and trajectory characteristics. Moreover,detailed numerical simulations of 155 mm dual-spin projectile are satisfactory agreement with the theoretical results.

关键词： Dual-spin projectile Fixed canards Control strategy Flight stability

Recent advances of covalent organic frameworks in electronic and optical applications

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Chinese Chemical Letters 2016年第8期27卷 1383-1394,1470页

作者： Li Ma Shan wang Xiao Feng Bo wang Key Laboratory of Cluster Science Ministry of Education of ChinaBeijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of ChemistryBeijing Institute of Technology

Covalent organic frameworks（COFs） as an emerging class of porous materials have achieved remarkable progress in recent *** high surface area,low mass densities,highly ordered periodic structures,and ease of functionalization make COFs exhibit superior potential in gas storage and separation,optoelectronic device and *** mini review gives a brief introduction of COFs and highlights their applications in electronic and optical fields.

关键词： Covalent organic frameworks Semiconduction Photoconduction Energy storage Chemosensor

Formal modeling and quantitative evaluation for information system survivability based on PEPA

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The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 88-96,113页

作者： wang Jian wang Hui-qiang ZHAO Guo-sheng Institute of Computer Science and Technology Harbin Engineering UniversityHarbin 150001 China

Survivability should be considered beyond security for information system. To assess system survivability accurately, for improvement, a formal modeling and analysis method based on stochastic process algebra is proposed in this article. By abstracting the interactive behaviors between intruders and information system, a transferring graph of system state oriented survivability is constructed. On that basis, parameters are defined and system behaviors are characterized precisely with performance evaluation process algebra （PEPA）, simultaneously considering the influence of different attack modes. Ultimately the formal model for survivability is established and quantitative analysis results are obtained by PEPA Workbench tool. Simulation experiments show the effectiveness and feasibility of the developed method, and it can help to direct the designation of survivable system.

关键词： survivability stochastic process algebra performanceevaluation process algebra formal modeling quantitativeevaluation

Effect of urbanization on the winter precipitation distribution in Beijing area

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Science China Earth Sciences 2009年第2期52卷 250-256页

作者： wang XiQuan wang ZiFa QI YanBin GUO Hu Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Jilin Province Weather Modification Offices Changchun 130062China Beijing Meteorological Bureau Beijing 100089China

According to the urbanization extent of Beijing area, and with 1980 as a turning point, the duration from 1961 to 2000 is divided into two periods: one is defined as the slow urbanization period from 1961 to 1980, and other one as the fast urbanization period from 1981 to 2000. Based on the 40-year’s precipi-tation data of 14 standard weather stations in Beijing area, the effect of urbanization on precipitation distribution is studied. It is found that there has been a noticeable and systematic change of winter precipitation distribution pattern between these two periods in Beijing area: in the slow urbanization period, the precipitation in the southern part of Beijing is more than that in the northern part; but in the fast urbanization period, the precipitation distribution pattern is reverse, i.e. the precipitation in the southern part is less than that in the northern part; But in other seasons, the precipitation distribution pattern did not change remarkably in general. The possible cause resulting in the change of winter precipitation distribution pattern, might be that with urban area extension, the effects of "urban heat island" and "urban dry island" become more and more intensified, and increase hydrometeors evapo-ration below precipitable cloud, and then cause less precipitation received on the ground surface in the downtown and the southern part. It is also noteworthy to further research why the precipitation distri-bution pattern does not change systematically in other seasons except winter after intense urbaniza-tion in Beijing area.

关键词： urbanization urban precipitation urban heat island urban dry island Beijing area

A model for parameter estimation of multistage centrifugal compressor and compressor performance analysis using genetic algorithm

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Science China(Technological Sciences) 2012年第11期55卷 3163-3175页

作者： CHU Fei wang FuLi wang XiaoGang ZHANG ShuNing College of in formation Science and Engineering Northeastern UniversityShenyang 110819China State Key Laboratory of Integrated Automation for Process Industries Northeastern UniversityShenyang 110819China

A model for performance prediction of multistage centrifugal compressor is proposed. The model allows the users to predict the compressor performance, e.g. pressure ratio, efficiency and losses using the compressor geometric information and speed by a stage stacking calculation based on the characteristics of each stage. To develop the compressor elemental stage charac- teristics, the compressor losses, such as incidence losses and friction losses, are mathematically modeled. For a composite sys- tems, for instance a gas turbine power plant, the performance of the multistage centrifugal compressor can be evaluated. Since some important parameters of the compressor model, e.g., the slip factor or, shock loss coefficient （and reference diameter DI, are hard to be determined by empirical laws, a genetic algorithm （GA） is used to solve the parameter estimation problem of the proposed model, and in turn the compressor performance analysis and parameters study are performed. The surge line for the multistage centrifugal compressor can also be determined from the simulation results. Furthermore, the model presented here provides a valuable tool for evaluating the multistage centrifugal compressor performance as a function of various operation parameters.

关键词： performance predication centrifugal compressor incidence loss genetic algorithm surge line