检索结果-南通市图书馆

Stabilization for discrete-time fuzzy systems with Takagi-Sugeno's models:reduce the complexity

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2010年第12期53卷 2506-2513页

作者： WANG LiKui 1 & LIU XiaoDong 2 1 School of Mathematics and Information Science,Nanchang Hangkong University,Nanchang 330063,China 2 Research center of Information and Control,Dalian University of Technology,Dalian 116024,China School of Mathematics and Information Science Nanchang Hangkong University Research center of Information and Control Dalian University of Technology

The problem of sate feedback control for discrete-time fuzzy systems with Takagi-Sugeno's models is investigated to reduce the computational burden.A stabilization condition is obtained by applying a new Lyapunov *** is shown that our new theorem is equivalent to an existing result in guaranteeing the stability of the fuzzy system but consumes less computational time than the *** effectiveness and the superiority of the proposed design approach are demonstrated by an example borrowed from the literature.

关键词： Takagi-Sugeno’s fuzzy model non-quadratic Lyapunov function linear matrix inequality

Similar component analysis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第12期16卷 1343-1347页

作者： ZHANG Hong~1**, WANG Xin~1, LI Junwei~2 and CAO Xianguang~1(1. Image center, Astronautics School, BeiHang University, Beijing 100083, China 2. The 207th Institute of the Second Academy of China Aerospace Science Industry Corporation, Beijing 100854, China) Image center Astronautics School BeiHang University Beijing 100083 China. 207th Institute of Second Academy of China Aerospace Science Industry Corporation Beijing 100854 China

A new unsupervised feature extraction method called similar component analysis (SCA) is proposed in this paper. SCA method has a self-aggregation property that the data objects will move towards each other to form clusters through SCA theoretically, which can reveal the inherent pattern of similarity hidden in the dataset. The inputs of SCA are just the pairwise similarities of the dataset, which makes it easier for time series analysis due to the variable length of the time series. Our experimental results on many problems have verified the effectiveness of SCA on some engineering application.

关键词： clustering feature extraction similar component.

Flow instability of buoyant-Marangoni convection in the LEC GaAs melt

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第4期51卷 397-406页

作者： CHEN ShuXian1 & LI MingWei2,3 1 Aviation Engineering Institute, Civil Aviation Flight University of China, Guanghan 618307, China 2 Institute of Power Engineering of Chongqing University, Chongqing 400030, China 3 Research center of Biological Function Information and Instruments of Chongqing University by Sec-ond-Term national 985 Project, Chongqing University, Chongqing 400030, China Aviation Engineering Institute Civil Aviation Flight University of China Guanghan 618307 China Institute of Power Engineering of Chongqing University Chongqing 400030 China

Flow transitions and instabilities have significant effects on the quality of the crystals. The flow and heat transfer in the LEC GaAs melt are numerically studied by a time-dependent and three-dimensional turbulent flow model. The effects of the change of the buoyancy and Marangoni force on the flow state are analyzed by changing the temperature difference between the crystal and the crucible walls. The results show that the flow will transform from axisymmetric steady flow to non-axisymmetric oscillatory flow when the temperature difference exceeds the critical value, and that the mechanism of the transition is attributed to the Marangoni instability. The critical temperature differences for the flow transitions corresponding to different melt depth H are numerically predicted. Several important characteristics of the non-axisymmetric buoyant-Marangoni convection are numerically observed and compared with that of the non-axisymmetric mixed convection coupled with crystal rotation.

关键词： flow transition flow instability buoyant-Marangoni convection mixed convection LEC GaAs melt

Nonlinear interactions between gravity waves and background winds

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第6期17卷 639-644页

作者： Liu Xiao1,2 and Xu Jiyao1(1. State Key Laboratory for Space Weather, center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100080, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China) State Key Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China Graduate University of Chinese Academy of Sciences Beijing 100039 China

Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.

关键词： gravity waves background winds vertical group velocity vertical wavelength nonlinear interactions.

Constructive proof of deficiency theorem of (g,f)-factor

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2010年第6期53卷 1657-1662页

作者： LU HongLiang1,& YU QingLin2 1center for Combinatorics,LPMC,Nankai University,Tianjin 300071,China 2Department of Mathematics and Statistics,Thompson Rivers University,Kamloops V2C5N3,Canada center for Combinatorics LPMC Nankai University Department of Mathematics and Statistics Thompson Rivers University

Berge(1958) gave a formula for computing the deficiency of maximum matchings of a *** generally,Lov'asz obtained a deficiency formula of(g,f)-optimal graphs and consequently a criterion for the existence of(g,f)-***,Lov'asz proved that there is one of these decompositions which is "canonical" in a *** this paper,we present a short constructive proof for the defficiency formula of(g,f)-optimal graphs,and the proof implies an efficient algorithm of time complexity O(g(V)|E|) for computing the ***,this proof implies this canonical decomposition via efficient algorithms(i.e.,in polynomial time).

关键词： deficiency factor alternating trail

Kalman filtering for time-delayed linear systems

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2006年第4期49卷 461-470页

作者： LU Xiao1,2 & WANG Wei1 1. Research center of Information and Control, Dalian University of Technology, Dalian 116024, China 2. Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China Research center of Information and Control Dalian University of Technology Shenzhen Graduate School Harbin Institute of Technology

This paper is to study the linear minimum variance estimation for discretetime systems. A simple approach to the problem is presented by developing re-organized innovation analysis for the systems with instantaneous and double time-delayed measurements. It is shown that the derived estimator involves solving three different standard Kalman filtering with the same dimension as the original system. The obtained results form the basis for solving some complicated problems such as H, fixed-lag smoothing, preview control, H, filtering and control with time delays.

关键词： discrete-time systems delayed measurements innovation analysis Riccati equations.

fMRI time series analysis based on stationary wavelet and spectrum analysis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第11期16卷 1171-1176页

作者： ZHI Lianhe~ 1,2,3 , ZHAO Xia~4, SHAN Baoci~1**, PENG Silong~5, YAN Qiang~1, YUAN Xiuli~1 and TANG Xiaowei~ 1,6 (1. Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China 2. Graduate School of Chinese Academy of Sciences, Beijing 100049, China 3. Department of Physics, Zhoukou Normal University, Zhoukou 466100, China 4. Research Imaging center, University of Texas Health Science center, San Antonio, Texas 78229, USA 5. national ASIC Design and Engineering center, Institute of Automation, Chinese Academy of Sciences, Beijing 100049, China 6. Department of Physics, Zhejiang University, Hangzhou 310027, China) Key Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method.

关键词： fMRI stationary wavelet transform spectrum analysis data analysis.

The HY-1 satellite and ground system in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2003年第2期22卷 301-308页

作者： Liu Jianqiang , Jiang Xingwei, Lin Mingsen national Satellite Ocean Application service of State Oceanic Administration, Beijing 100081, China, Natl. Satellite Ocean Appl. Serv. Beijing 100081 China

INTRODUCTIONWith the coming of the 21st century, we are faced the problems of the environment, re-sources and population. The ocean is regarded as supplier of resources such as food, minerals,energy and space, and plays an important role in sustainable economic development. At thesame time the ocean has a very important effect on the worldwide environmental changes.

关键词： HY-1 satellite ground system China

Integrating MODFLOW and GIS technologies for assessing impacts of irrigation management and groundwater use in the Hetao Irrigation District,Yellow River basin

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第11期52卷 3257-3263页

作者： XU Xu1,2, HUANG GuanHua1,2 & QU ZhongYi3 1 center for Agriculture Water Research, China Agricultural University, Beijing 100083, China 2 Chinese-Israeli International center for Research and Training in Agriculture, China Agricultural University, Beijing 100083, China 3 Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China center for Agriculture Water Research China Agricultural University Chinese-Israeli International center for Research and Training in Agriculture China Agricultural University Water Conservancy and Civil Engineering College Inner Mongolia Agricultura

Due to severe water scarcity, water resources used in agricultural sector have been reduced markedly in Hetao irrigation district. Application of water-saving practices (WSPs) is required for the sustainable agricultural development. The human activities including WSPs and increase of groundwater abstraction can lower down the groundwater table, which is helpful to the salinity control. Meanwhile, an excessively large groundwater table depth may result in negative impact on crop growth and fragile ecological environment. In this paper, the Jiefangzha irrigation system in Hetao irrigation district was selected as a typical area, a groundwater flow model based on ArcInfo Geographic Information System (GIS) was developed and implemented to quantify the effect of human activities on the groundwater system in this area. The preand post-processing of model data was performed efficiently by using the available GIS tools. The time-variant data in boundary conditions was further edited in Microsoft Excel with programs of Visual Basic for Application (VBA). The model was calibrated and validated with independent data sets. Application of the model indicated that it can well describe the effect of human activities on groundwater dynamics in Jiefangzha irrigation system.

关键词： groundwater flow modeling MODFLOW GIS water-saving practices irrigation district