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On Constructions of Optimal Truncated Low-Dimensional Dynamical Systems of Navier-Stokes equations

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Communications in Nonlinear Science and Numerical Simulation 1996年第3期1卷 27-31页

作者： Chuijie WU Hongliang ZRAO(Air Force Institute of Meteorology Nanjing, 211101)(LNM, Institute of Mechanics, cas, Beijing, 100080)e-mail: wucj@*** [b] Air Force Institute of Meteorology Nanjing 211101 China [a] LNM Institute of Mechanics cas Beijing 100080 China

An optimal metliod in constructing low-dimensional dynahacal systems ofNavier-Stokes equations has been outlined in this communication. Results on closed oropen domain viscous flows show that the new method is better ... 详细信息

关键词： Navier-Stokes equations Dynamical system. Optimization

Relationship between erosion and sediment yield in drainage basins of loess gully-hilly areas

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Journal of geographical Sciences 2001年第1期11卷 71-79页

作者： CHeN Hao (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

From a long-term point of view, the balance between erosion and sediment yield in a drainage system can basically realize, i.e., the delivery ratio can be close to 1. However, substantial variations among individual rainfall events or between annual delivery ratio exist, causing frequent sediment retaining or re-erosion and re-delivery of the retained sediments in a short period of time. Thus the delivery ratio will be 1. The sediment delivery ratio is closely related to the spatial distribution of rainfall and magnitude of rise and fall of peak flood and that of runoff depth in the drainage system. Delivery ratio of single event in a drainage system and changes of delivery capacity of silt-laden runoff in various classes of gullies can be expressed by transformation mechanism of shear force of a single rainstorm event with flood resulting from increase and decrease of peak flood per unit area.

关键词： delivery ratio interaction flood and geomorphology dynamic mechanism rainstorm flood

geochemical Characteristics and Tectonic Setting of the Laohushan Basalts, North Qilian Mountains

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Acta geologica Sinica(english edition) 2001年第4期75卷 452-457页

作者： QIAN Qing and ZHANg Qi Institute of geology and geophysics, cas, P. O. Box 9825, Beijing 100029 Institute of geology and geophysics CAS P. O. Box 9825 Beijing 100029 [?]2Qian Qing Born in 1969 graduated from the Peking University in 1992 obtained the master's degree in 1996 and doctor's degree in 1999 now an associated research professor in the Institute of geology and geophysics Chinese Academy of Sciences (CAS) mainly engaged in petrological and geochemical studies of volcanic rocks. Tel: 010–62008085 e-mail: qq613@kimo.com.tw or zhangqi@***.

The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidites, including sandstones, siltstones, cherts etc. Major elements show that the basalts are subalkaline tholeiites and may be analogous to ocean-floor basalts. except a few N-MORBs, most of the basalts are e-MORBs as indicated by incompatible element ratios such as (La/Ce)N, La/Sm, Ce/Zr, Zr/Y and Zr/Nb. Negative Nb anomaly is common but negative Zr, Hf and Ti anomalies are quite rare. Based on the geochemical characteristics, it is suggested that the Laohushan basalts were formed in a back-arc basin. eNd (t) of the basalts ranges between +3.0 and +8.9 and (87Sr/86Sr), ranges between 0.7030 and 0.7060, indicating a depleted mantle source which was mixed with more or less enriched mantle components. Furthermore, the petrography of the sandstones and geochemistry of the cherts suggest that the sediments were deposited near a continental margin.

关键词： North Qilian Mountains Laohushan basalts sediments geochemistry

Soil erosion and management on the Loess Plateau

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Journal of geographical Sciences 2001年第1期11卷 53-70页

作者： CAI Qiang-guo (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

The Loess Plateau is well known to the world for its intense soil erosion. The root cause for river sedimentation of Yellow River (Huanghe) and its resultant “hanging river” in certain section is soil and water loss on the Loess Plateau. The Loess Plateau has a long cultivation history, hence population growth, vegetation degeneration and plugging constitute the chief reason for serious soil and water loss on Loess Plateau. This paper analyses several successful cases and failures in soil conservation, presents practical soil conservation technique and related benefit analysis, and discusses some effective methods adopted in China in soil erosion control, research directions and future perspectives on Loess Plateau.

关键词： soil erosion control technique management Loess Plateau

Detonation initiation developing from the Richtmyer-Meshkov instability

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Acta Mechanica Sinica 2007年第4期23卷 343-349页

作者： H.H.Teng Z.L.Jiang Z.M.Hu LHD.Institute of Mechanics,cas.Beijing 100080,China LHD Institute of Mechanics CAS Beijing 100080 China

Detonation initiation resulting from the Richtmyer-Meshkov instability is investigated numerically in the configuration of the shock/spark-induced-deflagration interaction in a combustive gas mixture. Two-dimensional multi-species Navier-Stokes equations implemented with the detailed chemical reaction model are solved with the dispersion-controlled dissipative scheme. Numerical results show that the spark can create a blast wave and ignite deflagrations. Then, the deflagration waves are enhanced due to the Richtmyer-Meshkov instability, which provides detonation initiations with local environment conditions. By examining the deflagration fronts, two kinds of the initiation mechanisms are identified. One is referred to as the deflagration front acceleration with the help of the weak shock wave, occurring on the convex surfaces, and the other is the hot spot explosion deriving from the deflagration front focusing, occurring on the concave surfaces.

关键词： Hot spot Deflagration front acceleration Detonation initiation Richtmyer-Meshkov instability

Delineation of boundary between tropical/subtropical in the middle section for eco-geographic system of South China

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Journal of geographical Sciences 2001年第1期11卷 80-86页

作者： WU Shao-hong, ZHeNg Du (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

This paper discusses division on tropical/subtropical boundary of middle section in South China. This discussion results in new understanding on eco-geographic regions and their boundaries, especially on gradual changes of natural conditions between eco-geographic regions. It analyzes results of the same area by other researchers, clarifies differences and causes of the differences for the results. Boundaries of eco-geographic regions cannot be drawn as a line as changes from tropical to subtropical are gradual. Therefore, for an eco-geographic region like tropical zone, definite boundaries must be mapped while gradual changes are considered. Temperature, vegetation and soil are the indexes to divide tropical and subtropical. After indexes of tropical zone are confirmed, data of annual average index reflect general state of the tropical zone. Line from such data is called “tropical boundary”. On the other hand, affected by the monsoon climate, some years are hotter and some are cooler. In hotter years, temperature of north area of tropical boundary reaches tropical state whereas in cooler years, such area moves southward. Boundary of the hottest year is called annual tropical line and that of the coolest year true tropical line. Temperatures in areas south to annual tropical line can probably reach tropical in some years. Temperatures in areas south to real tropical line reach tropical every year. The area from true tropical to annual tropical is called tropical fluctuating zone. Therefore, new concepts of tropical, annual tropical, true tropical and tropical fluctuating zone are formed to understand tropical area from a new point of view in the paper. Based on the indexes of climate, vegetation and soil, boundaries of tropical, annual tropical, true tropical and tropical fluctuating zone of the study area are established. The tropical fluctuating zone explains different locating of different researchers. The paper also puts forward a new method to display boundary

关键词： eco-geographic region tropical annual tropical true tropical tropical fluctuating zone

“greatest lake period” and its palaeo-environment on the Tibetan Plateau

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Journal of geographical Sciences 2001年第1期11卷 34-42页

作者： LI Bing-yuan, ZHU Li-ping (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

The “greatest lake period” means that the lakes are in the stage of their maximum areas. As the paleo lake shorelines are widely distributed in the lake basins on the Tibetan Plateau, the lake areas during the “greatest lake period” may be inferred by the last highest lake shorelines. They are several, even tens times larger than that at present. According to the analyses of tens of lakes on the Plateau, most dating data fell into the range of 40-25 ka BP, some lasted to 20 ka BP. It was corresponded to the stage 3 of marine isotope and interstitial of last glaciation. The occurrence of maximum areas of lakes marked the very humid period on the Plateau and was also related to the stronger summer monsoon during that period.

关键词： Tibetan Plateau greatest lake period highest lake levels interstitial of last glaciation paleo-monsoon

On coordinated development of oasis and environment in arid area

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Journal of geographical Sciences 2001年第1期11卷 117-121页

作者： FU Xiao-feng, LI Zhe (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

Based upon the formation and evolution of oasis and the factors restricting the coordinated development of oasis economy and environment, this paper presents a goal of the development in coordination. It suggests that the sustainable survival and development of oasis could be ensured only if the oasis-desert and water source ecology are managed in a combined way to form a macro system. In light with the above mentioned, the approach to the development of economy and environment of oasis in arid area should depend upon the establishment of an oasis ecological and economic system, which suits the arid environment and promotes the efficiency of resource configuration, stabilizes economic increment and benefits ecological development.

关键词： oasis development environment arid area

Structural patterns of land types and optimal allocation of land use in Qinling Mountains

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Journal of geographical Sciences 2001年第1期11卷 99-109页

作者： LIU Yan-sui, DeNg Xiang-zheng (Institute of geographic Sciences and Natural Resources Research, cas, Beijing 100101, China) cas Institute of Geographic Sciences and Natural Resources Research Beijing China (GRID:grid.9227.e) (ISNI:***)

The case study based on Qinling Mountains in Shaanxi Province of China, in virtue of the information from TM image, classifies the land types and analyzes their spatial and temporal differential law, and puts forward three structural patterns of land types in mountainous areas, namely, spatial, quantitative and qualitative structures of mountainous land types. Furthermore, it has been noticed that the analysis of structural patterns can disclose the heterogeneity and orderliness of combination of land types, which can lay the theoretic foundation for comprehensively recognizing ecological characteristics and succession law of structure and function of land types. After the all-around comparative analysis, an optimal allocation of land use in Qinling Mountains has been put forward according to the principle of sustainable development and landscape ecology, which can lay the scientific foundation in practice for the structural adjustment and distribution optimization from the macro level to micro level.

关键词： land types succession of land types structural patterns optimal allocation Qinling Mountains