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A Catastrophe model to Assess Soil Restoration Under Ecological Restoration in the Red Soil Hilly Region of China

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Pedosphere 2017年第4期27卷 778-787页

作者： CHEN Zhiqiang CHEN Zhibiao BAI Liyue ZENG Yuee School of Geographical Sciences Fujian Normal UniversityFuzhou 350007China State Key Laboratory of Humid Subtropical Mountain Ecology Fuzhou 350007China Institute of Geography Sciences Fujian Normal UniversityFuzhou 350007China Rural Work Research Center of Fujian Agriculture Department Fuzhou 350007China

Current methods that utilize simple data or models to evaluate soil restoration under ecological restoration are not sufficiently rigorous.Soil restoration under ecological restoration measures was evaluated in the red soil hilly region of China by applying the catastrophe model.Among 89 soil sites selected,26(29.21%) were in the middle lobe,10(11.24%) in the upper lobe,and 53(70.79%)in the lower lobe of the process surface in the Cusp catastrophe model.The catastrophic direction of the 26 unstable soil sites was to the upper lobe of the process surface according to vegetation cover change and fieldwork.There was a significant negative correlation of the variation in bifurcation set(? value) with vegetation cover increase,and a higher vegetation cover increase was related to higher unstable probability.The four ecological restoration measures were listed in the order:low-quality forest improvement(LQFI)>arbor-bush-herb mixed plantation(ABHMP)>orchard improvement(OI)>closing measures(CM) according to the proportions of unstable soil sites,which were all higher than no restoration measure,while they were in the order:LQFImodel.

关键词： 3S technologies, Catastrophe theory, Cusp catastrophe model, farmers' assessment, process surface, soil and waterlosses, soil quality integrated index

Application of ensemble kalman filter to geophysical parameters retrieval in remote sensing:A case study of kernel-driven BRDF model inversion

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Science China Earth Sciences 2006年第6期49卷 632-640页

作者： QIN Jun1, YAN Guangjian1, LIU Shaomin1, LIANG Shunlin2, ZHANG Hao1, WANG Jindi1 & LI Xiaowen1 1. State Key Laboratory of Remote Sensing Science, School of Geography and Remote Sensing, Research Center for RS&GIS, Beijing Normal University, Beijing 100875, China 2. Department of Geography, 2181 Lefrak Hall, University of Maryland, College Park, MD20742, USA State Key Laboratory of Remote Sensing Science School of Geography and Remote Sensing Research Center for RS&GIS Beijing Normal University Beijing China Department of Geography 2181 Lefrak Hall University of Maryland College Park USA

The use of a priori knowledge in remote sensing inversion has great implications for ensuring the stability of inversion process and reducing uncertainties in retrieved results, especially under the condition of insufficient observations. Common optimization algorithms have difficulties in providing posterior distribution and thus cannot directly acquire uncertainties in inversion results, which is of no benefit to remote sensing application. In this article, ensemble Kalman filter (EnKF) has been introduced to retrieve surface geophysical parameters from remote sensing observations, which has the capability of not merely obtaining inversion results but also giving its posterior distribution. To show the advantage of EnKF, it is compared to standard MODIS AMBRALS algorithm and highly effi-cient global optimization method SCE-UA. The inversion abilities of kernel-driven BRDF models with different kernel combinations at several main cover types are emphatically discussed when observa-tions are deficient and a priori knowledge is introduced into inversion.

关键词： remote sensing inversion, a priori knowledge, posterior distribution, ensemble kalman filter, BRDF, kernel-driven model, albedo.

An improved dynamic subgrid-scale model and its application to large eddy simulation of rotating channel flows

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 463-476页

作者： LIU Nansheng LU Xiyun ZHUANG Lixian Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China

A new dynamic subgrid-scale (SGS) model, which is proved to satisfy the principle of asymptotic material frame indifference (AMFI) for rotating turbulence, is proposed based on physical and mathematical analysis. Comparison with direct numerical simulation (DNS) results verifies that the new SGS model is effective for large eddy simulation (LES) on rotating turbulent flow. The SGS model is then applied to the LES of the spanwise rotating turbulent channel flow to investigate the rotation effect on turbulence characteristics, budget terms in the transport equations of resolved Reynolds stresses, and flow structures near the wall regions of the rotating channel.

关键词： large eddy simulation (LES), dynamic subgrid-scale (SGS) model, rotating turbulent channel flow,asymptotic material frame indifference (AMFI).

The study on Sanmenxia annual flow forecasting in the Yellow River with mix regression model

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Science China(Technological Sciences) 2004年第Z1期47卷 118-126页

作者： JIANG Xiaohui1, LIU Changming1,2, WANG Yu3 & WANG Hongrui1 1. Beijing Normal University, Beijing 100875, China 2. Institute of Geographic Science and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China 3. Reconnaissance, Planning, Design and Research Institute, YRCC, Zhengzhou 450003, China Beijing Normal University Beijing China Institute of Geographic Science and Natural Resources Chinese Academy of Sciences Beijing China Reconnaissance Planning Design and Research Institute YRCC Zhengzhou China

This paper established mix regression model for simulating annual flow, in which annual runoff is auto-regression factor, precipitation, air temperature and water consumption are regression factors; we adopted 9 hypothesis climate change schemes to forecast the change of annual flow of Sanmenxia Station. The results show : (1) When temperature is steady, the average annual runoff will increase by 8.3% if precipitation increases by 10%; when precipitation decreases by 10%, the average annual runoff will decrease by 8.2%; when precipitation is steady, the average annual runoff will decrease by 2.4% if temperature increases 1℃; if temperature decreases 1℃, runoff will increase by 1.2%. The mix regression model can well simulate annual runoff. (2) As to 9 different temperature and precipitation scenarios, scenario 9 is the most adverse to the runoff of Sanmenxia Station of Yellow River; i.e. temperature increases 1℃ and precipitation decreases by 10%. Under this condition, the simulated average annual runoff decreases by 10.8%. On the contrary, scenario 1 is the best to the enhancement of runoff; i.e. when temperature decreases 1 ℃ precipitation will increase by 10%, which will make the annual runoff of Sanmenxia increase by 10.6%.

关键词： forecast annual flow, mix regression model, Sanmenxia Station

A microcosmic discrete occupant evacuation model based on individual characteristics

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Science China(Technological Sciences) 2004年第5期47卷 608-615页

作者： YANG Lizhong LI Jian ZHAO Daoliang FANG Weifeng FAN Weicheng State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China

The research of occupant evacuation in an emergency is of great benefit to building design and evacuation guidance. In this paper a microcosmic discrete evacuation model based on Cellular Automata (CA) is presented, in which the occupants?individual characteristics are considered. Thus, our model has given a description of evacuation route choice with influencing factors, including: individual knowledge of the building, individual realization of the emergency development, and the attractive and repulsive force between occupants. This model differs somewhat from other models in the attention to the associative and separate effect of influencing factors, based on occupants behaviors. In addition, the model could reveal the phenomenon of escape in fire, as those simulations involving a fire condition have shown.

关键词： evacuation, cellular automata, microcosmic discrete model, occupant behavior, fire.

3-D network model and its parameter calibration

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Science China Mathematics 2002年第10期45卷 1351-1360页

作者：刘晓宇梁乃刚李敏 Stt. Key Lab. of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

A material model, whose framework is parallel spring-bundles oriented in 3-D space, isproposed. Based on a discussion of the discrete schemes and optimum discretization of the solidangles, a 3-D network cell consisted of one-dimensional components is developed with its geomet-rical and physical parameters calibrated. It is proved that the 3-D network model is able to exactlysimulate materials with arbitrary Poisson ratio from 0 to 1/2, breaking through the limit that the pre-vious models in the literature are only suitable for materials with Poisson ratio from 0 to 1/3. A sim-plified model is also proposed to realize high computation accuracy within Iow computation cost.Examples demonstrate that the 3-D network model has particular superiority in the simulation ofshort-fiber reinforced composites.

关键词： strain energy stiffness modulus, orientation component, network model, poisson ratio.

3D mathematical model for suspended load transport by turbulent flows and its applications

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Science China(Technological Sciences) 2004年第2期47卷 237-256页

作者： LU Yongjun1,DOU Guoren1,HAN Longxi2,SHAO Xuejun3 & YANG Xianghua1,3 1.Nanjing Hydraulic Research Institute,Nanjing 210029,China 2.College of Environmental Engineering of Hohai University,Nanjing 210098,China 3.Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China Nanjing Hydraulic Research Institute Nanjing China College of Environmental Engineering of Hohai University Nanjing China Department of Hydraulic Engineering Tsinghua University Beijing China

This paper presents a 3D mathematical model for suspended load transport in turbulent flows. Based on Dous stochastic theory of turbulent flow, numerical schemes of Reynolds stresses for anisotropic turbulent flows were obtained. A refined wall function was employed to treat solid wall boundaries. The equations for 2D suspended load motion and sorting of bed material have been expanded into 3D cases. Numerical results are validated by the measured data of the Gezhouba Project, and proved to be in good agreement with the experimental. The present method has been employed to simulate sediment erosion and deposition in the dam area of Three Gorges Project, and for the operation of the project, siltation process and deposition pattern in the near-dam area of the reservoir, size distribution of the deposits and bed material, and flow fields and sediment concentration fields at different time and elevations are predicted. The predicted results are close to the experimental observations in physical model studies. Thus, a new method is established for 3D simulation of sediment motion in dam areas of multi-purpose water projects.

关键词： turbulent flows, Dou's stochastic theory, nonuniform suspended load, riverbed erosion and deposition, 3D mathematical model, Three Gorges Project.

Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media

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Science China Mathematics 2002年第6期45卷 808-816页

作者：蔡睿贤张娜 Inst. of Engineering Thermophysics Chinese Academy of Sciences Beijing 100080 China

Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model an improved Darcy model describing the natural convection in porous media. Besides their important theoretical meaning (for example, to analyze the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions to promoting the develop ment of computational heat and mass transfer. For instance, we can use them to check the accuracy,convergence and effectiveness of various numerical computational methods and to improve numerical calculation skills such as differential schemes and grid generation ways.

关键词： explicit analytical solution, porous medium, natural convection, Brinkman model, anisotropic.

Development of distributed time-variant gain model for nonlinear hydrological systems

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Science China Earth Sciences 2005年第6期48卷 713-723页

作者： XIA Jun1, 2, WANG Gangsheng1, TAN Ge1, YE Aizhong2 & G. H. Huang3 1. Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2. State Key Laboratory of Water Resources & Hydropower Engineering Sciences, Wuhan University, Wuhan 430072, China 3. Faculty of Engineering, University of Regina, 3737 Wascana Parkway, Regina, Sask., S4S 0A2, Canada Correspondence should be addressed to Xia Jun Key Laboratory of Water Cycle & Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China State Key Laboratory of Water Resources & Hydropower Engineering Sciences Wuhan University Wuhan China Faculty of Engineering University of Regina Sask Canada

In this paper, a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach. Two models, i.e. the time-variant gain model (TVGM) and the distributed time-variant gain model (DTVGM) that are built on the platform of Digital Elevation model (DEM), Remote Sensing (RS) and Unit Hydro-logical Process were proposed. The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern China and the Chaobai River basin located in the semihumid region of northern China. The results indicate that, in addition to the classic dynamic differential approach to describe nonlinear processes in hy-drological systems, it is possible to study such complex processes through the proposed sys-tematic approach to identify prominent hydrological relations. The DTVGM, coupling the advan-tages of both nonlinear and distributed hydrological models, can simulate variant hydrological processes under different environment conditions. Satisfactory results were obtained in fore-casting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation.

关键词： hydrological process, nonlinearity, time-variant gain model, distributed hydrological model.