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| 1 | An Eddy-Permitting Oceanic General Circulation Model and Its Preliminary Evaluation显示文摘An eddy-permitting, quasi-global oceanic general circulation model, LICOM (LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics) Climate System Ocean Model), with a uniform grid of 0.5? × 0.5? is established. Forced by wind stresses from Hellerman and Rosenstain (1983), a 40-yr integration is conducted with sea surface temperature and salinity being restored to the Levitus 94 datasets. The evaluation of the annual mean climatology of the LICOM control run shows that the large-scale circulation can be well reproduced. A comparison between the LICOM control run and a parallel integration of L30T63, which has the same framework but a coarse resolution, is also made to con?rm the impact of resolution on the model performance. On account of the reduction of horizontal viscosity with the enhancement of the horizontal resolution, LICOM improves the simulation with respect to not only the intensity of the large scale circulations, but also the magnitude and structure of the Equatorial Undercurrent and South Equatorial Current. Taking advantage of the ?ne grid size, the pathway of the Indonesian Through?ow (ITF) is better represented in LICOM than in L30T63. The transport of ITF in LICOM is more convergent in the upper layer. As a consequence, the Indian Ocean tends to get warmer in LICOM. The poleward heat transports for both the global and individual basins are also signi?cantly improved in LICOM. A decomposed analysis indicates that the transport due to the barotropic gyre, which primarily stands for the barotropic e?ect of the western boundary currents, plays a crucial role in making the di?erence. | 刘海龙 张学洪 李薇 俞永强 宇如聪 | 2004 | Advances in Atmospheric Sciences2004，21，5： | 68 |
| 2 | Development of distributed time-variant gain model for nonlinear hydrological systems显示文摘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. | 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 | 2005 | Science China Earth Sciences2005，48，6： | 32 |
| 3 | Numerical simulation of air-water two-phase flow over stepped spillways显示文摘Stepped spillways for significant energy dissipation along the chute have gained interest and popularity among researchers and dam engineers. Due to the com- plexity of air-water two-phase flow over stepped spillways, the finite volume computational fluid dynamics module of the FLUENT software was used to simulate the main characteristics of the flow. Adopting the RNG k-ε turbulence model, the mixture flow model for air-water two-phase flow was used to simulate the flow field over stepped spillway with the PISO arithmetic technique. The numerical result successfully reproduced the complex flow over a stepped spillway of an experiment case, including the interaction between entrained air bubbles and cavity recirculation in the skimming flow regime, velocity distribution and the pressure profiles on the step surface as well. The result is helpful for under-standing the detailed information about energy dissipation over stepped spillways. | CHENG Xiangju1, CHEN Yongcan1 & LUO Lin2 1. Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China 2. State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China | 2006 | Science China(Technological Sciences)2006，49，6： | 23 |
| 4 | Quantitative Modelling of Multiphase Lithospheric Stretching and Deep Thermal History of Some Tertiary Rift Basins in Eastern China显示文摘The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the basins as the rifting process cannot be accurately described by a simple (one episode) stretching model. The study shows that the multiphase stretching model, combined with the back-stripping technique, can be used to reconstruct the subsidence history and the stretching process of the lithosphere, and to evaluate the depth to the top of the asthenosphere and the deep thermal evolution of the basins. The calculated results obtained by applying the quantitative model to the episodic rifting process of the Tertiary Qiongdongnan and Yinggehai basins in the South China Sea are in agreement with geophysical data and geological observations. This provides a new method for quantitative evaluation of the geodynamic process of multiphase rifting occurring during the Tertiary in eastern China. | 林畅松 张燕梅 李思田 刘景彦 仝志刚 丁孝忠 李喜臣 | 2002 | Acta Geologica Sinica(English Edition)2002，76，3： | 21 |
| 5 | A cellular automata evacuation model considering friction and repulsion显示文摘There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed and efficiency. Most former evacuation models focus on the attraction force, while repulsion and friction are not well modeled. As a kind of multi-particle self-driven model, the social force model introduced in recent years can represent those three forces but with low simulation efficiency because it is a continuous model with complex rules. Discrete models such as the cellular automata model and the lattice gas model have simple rules and high simulation efficiency, but are not quite suitable for interactions’ simulation. In this paper, a new cellular automata model based on traditional models is introduced in which repulsion and friction are modeled quantitatively. It is indicated that the model can simulate some basic behaviors, e.g. arching and the “faster-is-slower” phenomenon, in evacuation as multi-particle self-driven models, but with high efficiency as the normal cellular automata model and the lattice gas model. | SONG Weiguo YU Yanfei FAN Weicheng Zhang Heping | 2005 | Science China(Technological Sciences)2005，48，4： | 19 |
| 6 | Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern China显示文摘Climatic change has significant impacts on snow cover in mid-latitude mountainous re- gions, in the meantime, spatial and temporal changes of snow cover and snowmelt runoffs are con- sidered as sensitive indicators for climatic change. In this study, the upper Heihe Watershed in the Qilian Mountains was selected as a typical area affected by snow cover and snowmelt runoffs in northwestern China. The changes in air temperatures, precipitation, snowfall and spring snowmelt runoffs were analyzed for the period from 1956 to 2001. The results indicate that climatic warming was apparent, particularly in January and February, but precipitation just fluctuated without a clear trend. The possible changes of snowmelt runoffs in the upper Heihe watershed in response to a warming of 4℃ were simulated using Snowmelt Runoff Model (SRM) based on the degree-day factor algorithm. The results of the simulation indicate that a forward shifting of snow melting season, an increase in water flows in earlier melting season, and a decline in flows in later melting season would occur under a 4℃ warming scenario. | WANG Jian1 & LI Shuo2 1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. College of Geography, Nanjing Normal University, Nanjing 210097, China | 2006 | Science China Earth Sciences2006，49，8： | 18 |
| 7 | Theoretical analyses and numerical experiments of variational assimilation for one-dimensional ocean temperature model with techniques in inverse problems显示文摘In the present work, the data assimilation problem in meteorology and physical oceanography is re-examined using the variational optimal control approaches in combination with regularization techniques in inverse problem. Here the estimations of the initial condition, boundary condition and model parameters are performed simultaneously in the framework of variational data assimilation. To overcome the difficulty of ill-posedness, especially for the model parameters distributed in space and time, an additional term is added into the cost functional as a stabilized functional. Numerical experiments show that even with noisy observations the initial conditions and model parameters are recovered to an acceptable degree of accuracy. | HUANG Sixun1,2, HAN Wei1 & WU Rongsheng2 1. P. O. Box 003, Nanjing 211101,China 2. Key Laboratory of Meso-Scale Severe Weather /MOE, Department of Atmospheric Sciences, Nanjing University, Nanjing 210093, China Correspondence should be addressed to Huang Sixun | 2004 | Science China Earth Sciences2004，47，7： | 18 |
| 8 | Fiducial inference in the pivotal family of distributions显示文摘In this paper a family, called the pivotal family, of distributions is considered.A pivotal family is determined by a generalized pivotal model. Analytical results show that a great many parametric families of distributions are pivotal. In a pivotal family of distributions a general method of deriving fiducial distributions of parameters is proposed. In the method a fiducial model plays an important role. A fiducial model is a function of a random variable with a known distribution, called the pivotal random element, when the observation of a statistic is given.The method of this paper includes some other methods of deriving fiducial distributions. Specially the first fiducial distribution given by Fisher can be derived by the method. For the monotone likelihood ratio family of distributions, which is a pivotal family, the fiducial distributions have a frequentist property in the Neyman-Pearson view. Fiducial distributions of regular parametric functions also have the above frequentist property. Some advantages of the fiducial inference are exhibited in four applications of the fiducial distribution. Many examples are given, in which the fiducial distributions cannot be derived by the existing methods. | XU Xingzhong & LI Guoying Department of Mathematics, Beijing Institute of Technology, Beijing 100081, China Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100080, China | 2006 | Science China Mathematics2006，49，3： | 16 |
| 9 | Simulation of rainfall-runoff and watershed convergence process in the upper reaches of Heihe River Basin,July 2002显示文摘The watershed flow concentration scheme in the distributed hydrology-soil- vegetation model (DHSVM) is coupled with the mesoscale atmospheric model MM5 version 3.5, in which the Oregen States University land surface model (OSULSM) was involved. The flood event which happened in July 2002 in the upper reaches of Heihe river basin is simulated and the surface flow convergence process is shown with this coupled model. It has been concluded that times water head reaches each place of the basin are different. Water amount at each point is split-flow proportionally as the drops in elevation between it and neighbor points. Large part of the water amount pass away in greater slope direction and small part pass away in smaller slope one.Adding of the slope convergence makes the atmospheric model redistributes the surface water laterally. | GAO Yanhong L(U) Shihua CHENG Guodong | 2004 | Science China Earth Sciences2004，47，z1： | 13 |
| 10 | A MATHEMATICAL MODEL FOR UNSTEADY SEDIMENT TRANSPORT IN THE LOWER YELLOW RIVER显示文摘A one-dimensional mathematical model for unsteady sediment transport in the Lower Yellow River is developed. A coefficient of sediment distribution is defined to represent the ratio of the bottom to the average concentration under the equilibrium conditions. The coefficient is not constant and is evaluated by using an empirical expression obtained by integrating the sediment concentration along water depth. The concentration distributions and the mean diameter distributions of suspended sediment in the transversal direction are also estimated in this model. A four-point (Preismann type) finite difference scheme and TDMA are employed in the numerical method. Three typical floods occurd in 1977,1982 and 1996, respectively, in the Lower Yellow River from Tiexie to Shunkou with a length of 393.67km are numerically simulated with the model. The computed results, such as the water stage, discharge, and sediment concentration agree well with the measured data. | ZHANG Hongwu1, HUANG Yuandong1 and ZHAO Lianjun2 1 Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China 2 Yellow River Institute of Hydraulic Research, Zhengzhou 450003, China | 2001 | International Journal of Sediment Research2001，16，2： | 13 |
| 11 | Numerical modeling of secondary migration and its applications to Chang-6 Member of Yanchang Formation (Upper Triassic), Longdong area, Ordos Basin, China显示文摘Mathematic modeling, established on the basis of physical experiments, is becoming an increasingly important tool in oil and gas migration studies. This technique is based on the observation that hydrocarbon migration tends to take relative narrow pathways. A mathematical model of hydrocarbon migration and accumulation is constructed using the percolation theory. It is then calibrated using physical experimental results, and is tested under a variety of conditions, to understand the applicability of the model in different migration cases. Through modeling, dynamic conditions of large-scale migration pathways within homogeneous formations can be evaluated. Basin-scale hydrocarbon migration pathways and their characteristics are analyzed during the model application to the Chang-8 Member of the Triassic Yanchang Formation in Longdong area of Ordos Basin. In heterogeneous formations, spatial changes in fluid potential determine the direction of secondary migration, and heterogeneity controls the characteristics and geometry of secondary migration pathways. | LUO XiaoRong YU Jian ZHANG LiuPing YANG Yang CHEN RuiYin CHEN ZhanKun ZHOU Bo | 2007 | Science China Earth Sciences2007，50，z2： | 13 |
| 12 | Empirical likelihood confidence regions of the parameters in a partially linear single-index model显示文摘In this paper, a partially linear single-index model is investigated, and three empirical log-likelihood ratio statistics for the unknown parameters in the model are suggested. It is proved that the proposed statistics are asymptotically standard chi-square under some suitable conditions, and hence can be used to construct the confidence regions of the parameters. Our methods can also deal with the confidence region construction for the index in the pure single-index model. A simulation study indicates that, in terms of coverage probabilities and average areas of the confidence regions, the proposed methods perform better than the least-squares method. | XUE Liugen~1 & ZHU Lixing~2 1. College of Applied Sciences,Beijing University of Technology,Beijing 100022,China 2. Department of Mathematics,Hong Kong Baptist University,Hong Kong,China | 2005 | Science China Mathematics2005，48，10： | 13 |
| 13 | A bi-directional gap model for simulating the directional thermal radiance of row crops显示文摘Row crops are a kind of typical vegetation canopy between discrete canopy and continuous canopy. Kimes et al. studied the directional thermal radiation of row crops using the geometrical optical model, which simplified row structure as 'box' and neglected the gap among foliage and did not consider the emissivity effects. In this work we take account of the gaps along illumination and viewing directions and propose a bi-direction gap model on the basis of the idea of gap probability of discrete vegetation canopy introduced by 'Li-Strahler' and inter-correlation of continuous vegetation developed by Kuusk. It can be used to explain 'hot spot' effects in thermal infrared region. The gap model has been validated by field experiment on winter wheat planted in shape of rows and results show that the gap model is better than Kimes' model in describing the directionality of thermal infrared emission for row crops. | CHEN Liangfu (陈良富) LIU Qinhuo (柳钦火) FAN Wenjie (范闻捷) LI Xiaowen (李小文) XIAO Qing (肖青) YAN Guangjian (闫广建) TIAN Guoliang (田国良) | 2002 | Science China Earth Sciences2002，45，12： | 12 |
| 14 | 3D mathematical model for suspended load transport by turbulent flows and its applications显示文摘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. | 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 | 2004 | Science China(Technological Sciences)2004，47，2： | 12 |
| 15 | Diagnosabilities of exchanged hypercube networks under the pessimistic one-step diagnosis strategy显示文摘The exchanged hypercube EH(s, t)(where s≥1 and t ≥1) is obtained by systematically reducing links from a regular hypercube Qs+t+1. One-step diagnosis of exchanged hypercubes which involves only one testing phase during which processors test each other is discussed. The diagnosabilities of exchanged hypercubes are studied by using the pessimistic one-step diagnosis strategy under two kinds of diagnosis models: the PMC model and the M M*model. The main results presented here are the two proofs that the degree of diagnosability of the EH(s, t) under pessimistic one-step t1/t1 fault diagnosis strategy is 2s where1≤s≤t(respectively, 2t, where 1≤t≤s) based on the PMC model and that it is also 2s where 1≤s≤t(respectively, 2t,where 1≤t≤s) based on the M M*model. | Jiarong Liang Ying Huang Liangcheng Ye | 2015 | Journal of Systems Engineering and Electronics2015，26，2： | 12 |
| 16 | One-step estimation for varying coefficient models显示文摘A one-step method is proposed to estimate the unknown functions in the varying coefficient models, in which the unknown functions admit different degrees of smoothness. In this method polynomials of different orders are used to approximate unknown functions with different degrees of smoothness. As only one minimization operation is employed, the required computation burden is much less than that required by the existing two-step estimation method. It is shown that the one-step estimators also achieve the optimal convergence rate. Moreover this property is obtained under conditions milder than that imposed in the two-step estimation method. More importantly, as only one minimization operation is employed, the full asymptotic properties, not only the asymptotic bias and variance, but also the asymptotic distributions of the estimators can be derived. The asymptotic distribution results will play a key role for making statistical inference. | TANG Qingguo & WANG Jinde Department of Mathematics, Nanjing University, Nanjing 210093, China Institute of Sciences, PLA University of Science and Technology, Nanjing 210007, China | 2005 | Science China Mathematics2005，48，2： | 11 |
| 17 | Large deviations for generalized compound Poisson risk models and its bankruptcy moments显示文摘We extend the classical compound Poisson risk model to the case where the premium income process, based on a Poisson process, is no longer a linear function.For this more realistic risk model, Lundberg type limiting results on the finite time ruin probabilities are derived. Asymptotic behaviour of the tail probabilities of the claim surplus process is also investigated. | HU Yijun | 2004 | Science China Mathematics2004，47，2： | 11 |
| 18 | Preliminary study on assessment of nutrient transport in the Taihu Basin based on SWAT modeling显示文摘With the Taihu Basin as a study area, using the spatially distributed and mechanism-based SWAT model, preliminary simulations of nutrient transport in the Taihu Basin during the period of 1995~2002 has been carried out. The topography, soil, meteorology and land use with industrial point pollution discharge, the loss of agricultural fertilizers, urban sewerage, and livestock drainages were all considered in the boundary conditions of the simulations. The model was calibrated and validated against water quality monitoring data from 2001 to 2002. The results show that the annual total productions of nitrogen (TN) and phosphorus (TP) into Lake Taihu are 40000t and 2000t respectively. Nutrient from the Huxi Region is a major resource for Lake Taihu. The non-point source (surface source) pollution is the main form of catchment sources of nutrients into Lake Taihu,occupied TN 53% and TP 56% respectively. TN and TP nutrients from industrial point pollution discharge are 30% and 16%, and sewerage in both forms of point source and non-point source are TN 31% and TP 47%. Both the loss of agricultural fertilizers and livestock drainages from the catchment should be paid more attention as an important nutrient source. The results also show that SWAT is an effective model for the simulation of temporally and spatially nutrient changes and for the assessment of the trends in a catchment scale. | LAI Geying, YU Ge & GUI Feng Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China The Graduate School of the Chinese Academy of Sciences, Beijing 100039, China Key Lab of Poyang Lake Ecological Environment and Resource Development, Jiangxi Normal University, Nanchang 330027, China | 2006 | Science China Earth Sciences2006，49，z1： | 11 |
| 19 | An asymptotic relationship for ruin probabilities under heavy-tailed claims显示文摘The famous Embrechts-Goldie-Veraverbeke formula shows that, in the classical Cramér-Lundberg risk model, the ruin probabilities satisfy R(x, ∞)~ p-1 e(x) if the claim sizes are heavy-tailed, where Fe denotes the equilibrium distribution of the common d.f. F of the i.i.d. claims, p is the safety loading coefficient of the model and the limit process is for x →∞. In this paper we obtain a related local asymptotic relationship for the ruin probabilities. In doing this we establish two lemmas regarding the n-fold convolution of subexponential equilibrium distributions, which are of significance on their own right. | 唐启鹤 | 2002 | Science China Mathematics2002，45，5： | 11 |
| 20 | Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin显示文摘Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1970, 1986 and 1999 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 20%. | CHEN Junfeng1,2, LI Xiubin2 & ZHANG Ming2 1. Institute of Remote Sensing & GIS, Peking University, Beijing 100871, China 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China | 2005 | Science China Earth Sciences2005，48，9： | 10 |
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