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Scenario simulation and forecast of land use/cover in northern china

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Chinese science Bulletin 2008年第9期53卷 1401-1412页

作者： LI YueChen 1,2,3 & HE ChunYang 3 1 college of Geographical science, Chongqing Normal university, Chongqing 400047, china 2 college of Resources and Environmental science, Chongqing university, Chongqing 400044, china 3 college of Resources science & technology, Beijing Normal university, Beijing 100875, china college of Geographical science Chongqing Normal University Chongqing 400047 China college of Resources and Environmental science Chongqing University Chongqing 400044 China college of Resources science & technology Beijing Normal University Beijing 100875 China

Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics (SD) model, Back Propagation Neural Network (BPNN) and Cellular Automata (CA) model is developed with land use/cover scenario changes in northern china in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors’ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern china.

关键词：土地利用中国北方细胞自动机系统动力学

Damage detection based on the propagation of longitudinal guided wave in a bimetal composite pipe

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Theoretical & Applied Mechanics Letters 2011年第2期1卷 20-24页

作者： Huixing Yun~(1,a) and Weiwei Zhang~2 1.college of Engineering Shanxi Agricultural university,Taigu 030801,china 2.college of science & Engineering,jinan university,guangzhou,china college of Engineering Shanxi Agricultural university Taigu 030801 China college of science & Engineering Jinan University Guangzhou China

This paper investigates the damage detection based on the propagation of guided wave in bimetal composite pipes,which can identify damage locations in both axial and circumferential *** feasibility of the method is showed by numerical simulations using FEM code ANSYS. Mode analysis is used to evaluate the guided wave mode and its structure,which can provide the basis of the mode selection in measurements *** guided wave propagation in a damaged pipe is computed by transient analysis.16 nodes around the pipe wall,as probes,are used to record the guided wave *** Pseudo Margenau-Hill distribution(PMHD)for each signal is carried out, three types of modes could be found,which are led mode,excited mode and lag mode in sequences. Based on the results,the arrival time of the excited mode could be used to locate damage in axial direction,and the energy distribution around the pipe of lag mode is consistent with the damage in circumferential *** simulation illustrated the possibility of detecting damage location in both axial and circumferential directions based on longitudinal ultrasonic guided waves only.

关键词： damage detection crack PMHD pipe

Physiological and ultralstructural changes of Chlorella sp. induced by UV-B radiation

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Progress in Natural science:Materials International 2005年第8期15卷 678-683页

作者： YU Juan1, TANG Xuexi1*, ZHANG Peiyu 1,2, TIAN Jiyuan1 and DONG Shuanglin1(1. Division of life science and technology, Ocean university of china, Qingdao 266003, china 2. college of life sciences, Qufu Normal university, Qufu 2731653, china) Division of life science and technology Ocean University of China Qingdao 266003 China. college of life sciences Qufu Normal University Qufu 2731653 China

In order to investigate the mechanisms of enhanced UV-B radiation on algae, the effects of UV-B radiation on the physiological and ultrastructural changes of Chlorella sp. were examined. The results showed that UV-B radiation could inhibit the growth and photosynthesis of microalgae. UV-B radiation at lower doses increased the photosynthetic pigment (chlorophyll a (Chla) and carotenoid (Car)) contents, while at higher doses of UV-B radiation Chla and Car contents were decreased. The ultrastructure of Chlorella sp. without exposure to UV-B showed that the thylakoid lamellae were clear and regular, the stroma of its chloroplast was apparent and clear. The globules with photosynthetic pigments and the cristae of mitochondria were clearly seen. After exposure to UV-B radiation at dose of 2.88 kJ/m2, the thylakoid lamellae of Chlorella sp. were lost and dissolved, the globules which contained photosynthetic pigments in chloroplast were bleached; some mitochondria cristae were dissolved; slight plasmolysis was found in some Chlorella sp. cells. After exposure to 5.76 kJ/m2 UV-B radiation, the thylakoid was in disarray and disintegration, plasmolysis was found in most cells, and the cell wall was broken and began to fall out. Many blank areas were observed in cells, mitochondria were seriously deformed and most of the mitochondria cristae were dissolved. Also, globules containing photosynthetic pigments in chloroplast were bleached and some empty globules were found in chloroplast. Therefore, UV-B radiation could damage cell structure of Chlorella sp., and this damage increased with the dose of UV-B radiation they exposed to.

关键词： UV-B radiation physiological changes ultrastructure Chlorella sp.

Direct adaptive neural control for stabilization of nonlinear time-delay systems

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science china(Information sciences) 2010年第4期53卷 800-812页

作者： WANG Min1,2*, ZHANG SiYing2, CHEN Bing2 & LUO Fei2 1college of Automation, South china university of technology, guangzhou 510641, china 2Institute of Complexity science, Qingdao university, Qingdao 266071, china 1. college of Automation South China University of Technology Guangzhou 510641 China2. Institute of Complexity Science Qingdao University Qingdao 266071 China

This paper is concerned with the problem of adaptive neural control for uncertain nonlinear strict-feedback time-delay systems with unknown virtual control coefficients. Radial basis function (RBF) neural networks are employed to directly approximate unknown virtual control signals, and then the adaptive neural control law is constructed by Lyapunov-Krasovskii functionals and backstepping. In order to avoid encountering a large number of adaptive parameters when using RBF neural networks as function approximators, an unknown constant, instead of unknown neural weights themselves, is employed as the estimated parameter. This technique makes only one adaptive parameter tuned online, thus significantly alleviating the burdensome computation. Meanwhile, some continuous functions are introduced to overcome the design difficulty originating from the use of one adaptive parameter. The proposed adaptive control guarantees the boundedness of all the signals in the closed-loop system. Simulation studies are presented to illustrate the effectiveness of the scheme.

关键词： nonlinear time-delay systems neural control adaptive control backstepping

ASYMPTOTIC ERROR EXPANSION FOR THE NYSTROM METHOD OF NONLINEAR VOLTERRA INTEGRAL EQUATION OF THE SECOND KIND

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Journal of Computational Mathematics 1994年第1期12卷 31-35页

作者： Han Guo-qiang (Dept. Of Comp, science, South china university of science and technology, guangzhou, china) 华南理工大学计算机系广东广州

While the numerical solution of one-dimensional Volterra integral equations of the second kind with regular kernels is well understood, there exist no systematic studies of asymptotic error expansion for the approximate solution. In this paper,we analyse the Nystrom solution of one-dimensional nonlinear Volterra integral equation of the second kind and show that approkimate solution admits an asymptotic error expansion in even powers of the step-size h, beginning with a term in h2. So that the Richardson's extrapolation can be done. This will increase the accuracy of numerical solution greatly.

关键词： ASYMPTOTIC ERROR EXPANSION FOR THE NYSTROM METHOD OF NONLINEAR VOLTERRA INTEGRAL EQUATION OF THE SECOND KIND

Thermal stability conditions of a weakly interacting Fermi gas in a weak magnetic field

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Progress in Natural science:Materials International 2009年第1期19卷 121-124页

作者： Fudian Mena,Hui Liub,Houyu Zhua a college of Physics science and technology,china university of Petroleum(East china),Dongying 257061,china b college of science,Anhui science and technology university,Fengyang 233100,china [a]college of Physics science and technology China University of Petroleum (East China) Dongying 257061 China [b]College of Science Anhui Science and Technology University Fengyang 233100 China

On the basis of the results derived from pseudopotential method and ensemble theory,thermal stability of a weakly interacting Fermi gas in a weak magnetic field is studied by using analytical method of *** exact analytical expressions of stability conditions at different temperatures are given,and the effects of interactions as well as magnetic field on the stability of the system are *** is shown that there is an upperlimit magnetic field for the stability of the system at low temperatures,and there is an attractive dividing value at high *** attractive interaction is lower than the critical value,the stability of the system has no request for magnetic field,but if attractive interaction is higher than the dividing value,a lower-limit magnetic field exists for the stability of the system.

关键词： Fermi gas Interaction Heat capacity Stability

Preparation of CaS:Eu^(2+) Phosphor by Microwave Heating Method and its Luminescence

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Chinese Chemical Letters 2000年第9期11卷 843-846页

作者： Peng Jun LIU Ying Liang LIU Department of Chemistry, jinan university, guangzhou 510632 Department of Chemistry, Hainan Normal college, Haikou 571158 jinan Univ Dept Chem Guangzhou 510632 Peoples R China Hainan Normal Coll Dept Chem Haikou 571158 Peoples R China

This is the first report of using the microwave heating technique to synthesize calcium sulphide activated by europium whose structure is determined as the face-centered cubic by conventional X-ray powder diffraction method. The phosphor has maximum excitation peaks located at 280 urn and 560 urn and the maximum emission of the phosphor is 630 nm. When the concentration of Eu^(2+) in CaS increases from I .0 × 10^(-5) to l.0 × 10^(-2) mole per mole host, the body colour of the calcium sulphide activated with europium changes from white, through light-red to pink to deep-red. The phosphor obtains the longest afterglow at the concentration of 0.1% Eu^(2+)doped and is a kind of good material excited by sunlight.

关键词： Microwave radiation heating calcium sulphide europium luminescence.

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2, Wu Yigen3 and Guo Shengli3(1. college of life sciences, Zhejiang university, Hangzhou 310058, china 2. Imaging Department of Tongji Hospital of Tongji university, Shanghai 200065, china 3. college of Mathematics and Physics, Nanjing university of Information science and technology, Nanjing 210044, china) college of life sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China college of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Properties of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin liquid crystal Co and Ni complexes

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science china Chemistry 2007年第4期50卷 488-493页

作者： LIU Wei1,2 & SHI TongShun2 1 college of Materials science and Engineering, Shandong university of technology, Zibo 255049, china 2 Department of Chemistry, Jilin university, Changchun 130023, china 1. college of Materials science and Engineering Shandong University of Technology Zibo 255049 China 2. Department of Chemistry Jilin University Changchun 130023 China

Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid crystal properties and display a hexagonal columnar discotic columnar (Colh) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, 1H NIVR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence, and surface photovoltage spectroscopy.

关键词： porphyrin liquid crystal cyclic voltammetry luminescence surface photovoltage spectroscopy