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961.
962.
本文回顾了W UMa型相接双星观测和理论研究的历史。总结了W UMa型相接双星观测特性和理论研究的成果。最后讨论了W UMa型相接双星理论模型研究中存在的问题及其解决这些问题的一些可行方法。 相似文献
963.
Today, most land surface process models have prescribed seasonal change of vegetation with regard to the exchange processes between land and the atmosphere. However, in order to consider the real interaction between vegetation and atmosphere and represent it best in a climate model, the vegetation growth process should be included. In other words, “life” should be brought into climate models. In this study, we have coupled the physical and biological components of AVIM (Atmosphere–Vegetation Interaction Model), a land surface model including plant ecophysiological processes, into the IAP/LASG L9 R15 GOALS GCM. To exhibit terrestrial vegetation information, the vegetation is given a high resolution of 1.5° by 1.5° to nest and couple the fine grid cells of land with the coarse grid cells of atmosphere, which is 7.5° longitude and 4.5° latitude. The simulated monthly mean surface air temperature and precipitation is close to the observations. The monthly mean Leaf Area Index (LAI) is consistent with the observed data. The global annual mean net primary production (NPP) simulation is also reasonable. The coupled model is stable, providing a good platform for research on two-way interaction between land and atmosphere, and the global terrestrial ecosystem carbon cycle. 相似文献
964.
M. Todd Walter Tammo S. Steenhuis Vishal K. Mehta Dominique Thongs Mark Zion Elliot Schneiderman 《水文研究》2002,16(10):2041-2046
The TOPMODEL framework was used to derive expressions that account for saturated and unsaturated flow through shallow soil on a hillslope. The resulting equations were the basis for a shallow‐soil TOPMODEL (STOPMODEL). The common TOPMODEL theory implicitly assumes a water table below the entire watershed and this does not conceptually apply to systems hydrologically controlled by shallow interflow of perched groundwater. STOPMODEL provides an approach for extending TOPMODEL's conceptualization to apply to shallow, interflow‐driven watersheds by using soil moisture deficit instead of water table depth as the state variable. Deriving STOPMODEL by using a hydraulic conductivity function that changes exponentially with soil moisture content results in equations that look very similar to those commonly associated with TOPMODEL. This alternative way of conceptualizing TOPMODEL makes the modelling approach available to researchers, planners, and engineers who work in areas where TOPMODEL was previously believed to be unsuited, such as the New York City Watershed in the Catskills region of New York State. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
965.
966.
《禹贡》——世界上最早的区域人文地理学著作 总被引:7,自引:0,他引:7
《禹贡》是中国最早的地理著作,本文从九州边界的确定、九州的区域研究模式、治山和治水的辩证关系与圈层地带结构模式的朦胧设计四个方面进行分析论述,认为《禹贡》是中国第一个奴隶制国家的国土综合整治开发建设总体规划,内分分区国土整治开发,分系统国土整治开发和国土整治开发战略。战略的最终目标是建立以华夏族为主的多民族统一国家。五服说在理论、内容、方法上,都显示了超前水平,具有一定学术价值和现实意义。本文认为它是世界上最早的区域人文地理学著作。 相似文献
967.
针对农田水利工程中农田纵横坡度设计与填挖土方计算问题,本文提出了三角网地面模型,推证了地面坐标转化为设计面坐标的坐标转化公式及三角形模型体积计算公式,给出了设计计算的逐步趋近算法。 相似文献
968.
George Chatzigeorgiou Vincent Picandet Abdelhafid Khelidj Gilles Pijaudier‐Cabot 《国际地质力学数值与分析法杂志》2005,29(10):1005-1018
A significant increase of the permeability of concrete upon micro‐cracking and a good correlation between the evolution of damage (material stiffness) and permeability are observed experimentally. The present contribution investigates this correlation theoretically, with the help of lattice analyses. Scaling analysis of lattices which contain elastic brittle bonds has shown that the material degradation should be described by the evolution of the material stiffness, or compliance, in a continuum setting (damage models). This result is reviewed and further documented in the first part of the paper. In the second part, hydro‐mechanical problems are considered with the construction of a hydraulic lattice, dual to the mechanical one. We observe that the average permeability upon micro‐cracking is the lattice scale‐independent controlling variable in the hydraulic problem. Additionally, results show that in a continuum poro‐mechanical approach, the evolution of the material permeability ought to be related to the elastic unloading stiffness, described e.g. with the help of continuum damage variables. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
969.
The paper describes prediction of thermal conductivity in terrestrial soil media. The model operates statistically by probability of occurrence for contacts between particular fractional compounds. It combines physical properties, specific to particular compounds, into one apparent conductance specific to the mixture. The concept of substituting grain compounds by hypothetical spheres is an essential tool to control porosity by the number of spheres, their radii and probability of contacts between them. The spheres are equal in radii. The spheres substitute compounds, regardless of the phase state. Control of particular phase states is possible by means of specific properties assigned to the spheres, at the input to the model. Performance of the model is successfully proved for many diverse terrestrial soil media in a wide range of bulk density, composition, water and water vapour content. Only the compounds of sand decline from the expected values and require introducing a correction to the thermal conductivity of sand grains. One possible explanation is that the thermal conductivity of sand is uncertain. Nevertheless, the model is useful and worth extending beyond terrestrial purposes. 相似文献
970.
速率面拟合法已应用于地壳垂直形变模型分析,本文利用这一曲面拟合理论研究了地壳水平形变模型,详细推导了相应的公式,并进行了模拟试算。 相似文献