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21.
Kohei Cho 《ISPRS Journal of Photogrammetry and Remote Sensing》1997,52(6):277-280
The first ISPRS software contest for computer-assisted teaching, CATCON, took place on July 12, 1996 at the ISPRS Congress in Vienna. The main objective of the contest was to promote the development and dissemination of good/user-friendly software packages for computer-assisted teaching. Ten software packages and one data set from six countries were nominated. All the software and the data set were demonstrated at the contest, and prizes were given to three software packages and to one data set. 相似文献
22.
Joachim Höhle 《ISPRS Journal of Photogrammetry and Remote Sensing》1997,52(6):266-276
The advanced personal computer models, new storage media such as CD-ROMs, new authoring tools and especially the Internet will influence the production of learning software for photogrammetry. Some examples of learning programs are presented, including experience from the development and use of these programs in the education of land surveyors. They demonstrate the progress made over the years as well as the potential and possibilities of computer-assisted teaching and learning in photogrammetry. 相似文献
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本文针对加拿大地球物理学家EdoNgland教授提出的问题,对M—P广义逆矩阵的递推算法进行了探分论述探讨的初步结果和对Greville递推算法的扩充。文中对算法的扩充给出严格的证明。 相似文献
25.
姚磊华 《吉林大学学报(地球科学版)》1997,(4)
对对流占优的三维溶质运移问题提出了分步广义迎风解法,首先利用N.N.Ya-nenko对水动力弥散方程分步求解的思想,将原来的一个定解问题分解为两个定解问题即对流定解问题和扩散定解问题,对对流定解问题采用广义迎风对偶单元均衡法求解,对扩散定解问题采用一般的Galerkin有限元法求解,不仅避免了用一般有限元法和有限差分法求解对流占优的地下水水质数学模型时常出现数值弥散和过量问题,而且避免了求节点速度这一步,节省运算步骤,对井点的浓度变化给出了更合适的求解方法。 相似文献
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C. J. Hapke 《地球表面变化过程与地形》2005,30(6):679-697
High‐resolution historical (1942) and recent (1994) digital terrain models were derived from aerial photographs along the Big Sur coastline in central California to measure the long‐term volume of material that enters the nearshore environment. During the 52‐year measurement time period, an average of 21 000 ± 3100 m3 km?1 a?1 of material was eroded from nine study sections distributed along the coast, with a low yield of 1000 ± 240 m3 km?1 a?1 and a high of 46 700 ± 7300 m3 km?1 a?1. The results compare well with known volumes from several deep‐seated landslides in the area and suggest that the processes by which material is delivered to the coast are episodic in nature. In addition, a number of parameters are investigated to determine what influences the substantial variation in yield along the coast. It is found that the magnitude of regional coastal landslide sediment yield is primarily related to the physical strength of the slope‐forming material. Coastal Highway 1 runs along the lower portion of the slope along this stretch of coastline, and winter storms frequently damage the highway. The California Department of Transportation is responsible for maintaining this scenic highway while minimizing the impacts to the coastal ecosystems that are part of the Monterey Bay National Marine Sanctuary. This study provides environmental managers with critical background data on the volumes of material that historically enter the nearshore from landslides, as well as demonstrating the application of deriving historical digital terrain data to model landscape evolution. Published in 2005 by John Wiley & Sons, Ltd. 相似文献
28.
The dynamic characteristics and migration of a pyramid dune 总被引:6,自引:0,他引:6
TAO WANG WEIMIN ZHANG ZHIBAO DONG JIANJUN QU ZHEFAN JING WANFU WANG JIANMIN FENG 《Sedimentology》2005,52(3):429-440
The results of wind tunnel experiments and field observations show that when the intersection angle between airflow direction and dune crest (ridge) line is > 30°, a reverse vortex is formed. Because of the convergence of sand streams from the windward and lee slopes at the crest, sand accumulates in the crestal region, causing vertical growth. Nevertheless, studies also show that the common asymmetry of the two slopes of a dune may significantly influence the evolution of arms of a pyramid dune. The migration rates of pyramid dunes are mediated by the interplay of their arms moving transversely and the vertical growth in response to the variations in wind regimes. Comparing the effects of airflow transverse to a given arm with longitudinal airflow, it is indicated that the transverse airflow is more significant in controlling the arms of pyramid dunes. The whole body of the studied pyramid dune, particularly the upper quarter section, migrated SE direction during the monitoring period. The patterns of wind erosion and deposition change alternately with seasonal variations in wind directions. The W, NE and SE sides undergo constant erosion, deposition and both erosion and deposition, respectively. The results of long-term monitoring of a pyramid dune show that southerly winds, resulting from a local circulation, markedly affect the transverse migration of the whole pyramid dune. 相似文献
29.
The behavior of granular materials is known to depend on its loose or dense nature, which in turns depends both on density and confining pressure. Many models developed in the past require the use of different sets of constitutive parameters for the same material under different confining pressures. The purpose of this paper is to extend a basic generalized plasticity model for sands proposed by Pastor, Zienkiewicz and Chan by modifying the main ingredients of the model flow—rule, loading–unloading discriminating direction and plastic modulus—to include a dependency on the state parameter. The proposed model is tested against the available experimental data on three different sands, using for each of them a single set of material parameters, finding a reasonably good agreement between experiments and predictions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
30.
The aim of this paper is to extend the generalized plasticity state parameter‐based model presented in part 1 to reproduce the hydro‐mechanical behavior of unsaturated soils. The proposed model is based on two pairs of stress–strain variables and a suitable hardening law taking into account the bonding—debonding effect of suction and degree of saturation. A generalized state parameter for unsaturated state is proposed to reproduce soil behavior using a single set of material parameters. Generalized plasticity gives a suitable framework to reproduce not only monotonic stress path but also cyclic behavior. The hydraulic hysteresis during a drying—wetting cycle and the void ratio effect on the hydraulic behavior is introduced. Comparison between model simulations and a series of experimental data available, both cohesive and granular, are given to illustrate the accuracy of the enhanced generalized plasticity equation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献