UNCERTAINTY AND SENSITIVITY ANALYSES OF SEDIMENT TRANSPORT FORMULAS     

Keh Chia YEH  Sen Long DENG 《国际泥沙研究》1998,(1)

ＵＮＣＥＲＴＡＩＮＴＹＡＮＤＳＥＮＳＩＴＩＶＩＴＹＡＮＡＬＹＳＥＳＯＦＳＥＤＩＭＥＮＴＴＲＡＮＳＰＯＲＴＦＯＲＭＵＬＡＳＫｅｈＣｈｉａＹＥＨ１ａｎｄＳｅｎＬｏｎｇＤＥＮＧ２ＡＢＳＴＲＡＣＴＩｎｖｉｅｗｏｆｔｈｅｒａｎｄｏｍｃｈａｒａｃｔｅｒｉｓｔ...  相似文献   

The development and applications of geographic information systems for urban and regional planning in the developing countries     

ANTHONY GAR-ON YEH 《International journal of geographical information science》2013,27(1):5-27

Abstract

In the past 10 years, geographic information systems (GIS) have been widely used in urban and regional planning in the developed countries in Australia, North America and Europe. However, the use of GIS in urban and regional planning in the developing countries is limited and still at an early stage of development. This paper examines the current use of GIS in urban and regional planning in the developing countries in Asia. The major hindrances in the use of GIS in the developing countries is related not so much to the technology of GIS but more to data availability, leadership, organization structure and planning practice. For GIS to be more useful to urban and regional planning in the developing countries the development of a sustainable strategy in developing GIS and staff training is needed. International assistance agencies and GIS software companies can play an active role in making GIS available and usable to the planners in the developing countries.  相似文献   

长波的垂直結构和它的移动与发展的关系     

叶篤正  陈雄山 《气象学报》1963,33(1):25-36

本文利用线性两层模式討論了对流层上部和下部扰动的发展和移动,以及它們之間相互关系。有以下主要結果: 1.一般常用的“溫度波落后于气压波,扰动发展”这一規則,对于超长波(波长大于10000公里)只适用于对流层上部,对于波长为7000公里左右的长波自对流层中部以上皆可应用,对于較短的长波整个对流层皆可应用。 2。当槽线或脊线随高度向西傾斜时,扰动的上层发展,下层阻尼;向东傾斜时,上层阻尼,下层发展;当时,上下层同时发展. 3.溫度波和高度波的移速可以不同,甚至方向可以相反;无論在上层或下层,当脊移进輻散区或槽移进輻合区时,扰动发展;当脊移进輻合区或槽移进輻散区时,扰动阻尼. 4.扰动的振幅和移速随时間而变,它不仅决定于基本流場的参数和扰动的波长,同时决定于扰动本身的上下結构. 5.周期性变化的稳定波在发展时期,其振幅的发展一天可达两倍半以上.因此日常所观測到的环流的巨大变化是否都属于一般所謂的西风带不稳定的現象值得深入研究.  相似文献   

约束性单元自动演化CA模型及可持续城市发展形态的模拟   总被引：100，自引：7，他引：93  

黎夏  叶嘉安 《地理学报》1999,54(4):289-298

单元自动演化ＣＡ可以大大增强ＧＩＳ的空间模型能力,在国外被越来越多地应用于城市发展演化过程的模拟。本文探讨了如何通过ＣＡ与ＧＩＳ的结合来进行可持续土地发展规划的新方法。提出了基于约束性的ＣＡ模型,具体分析了局部、区域以及全局约束性对ＣＡ模型结果的影响。并将灰度的概念引起ＣＡ模型中来反映状态连续的变化,克服常规ＣＡ模型的缺陷。将该模型应用于球江三角洲地区来获得合理的城市发展空间布局,取得了较好的效果  相似文献   

单斜辉石的 X 射线粉末法研究          下载免费PDF全文

叶大年  金成伟  彭志忠 《地质科学》1975,10(2):132-149

辉石是最重要的造岩矿物之一。无论是研究火成岩,变质岩,还是研究深部地质或月球岩石都离不开辉石的鉴定和研究。在工艺岩石学(例如铸石学)的研究中辉石鉴定问题也极为重要,尤其是X射线粉末法鉴定。因此,近五十年来很多人对辉石的X射线粉末图进行过研究。为了研究辉石类质同象对晶格常数的影响及其和成因的关系,各种辉石(主  相似文献   

铸石结晶过程中球体的发育特征   总被引：1，自引：0，他引：1       下载免费PDF全文

金成伟  叶大年 《地质科学》1974,9(3):227-233

在火成岩、变质岩、混合岩中,“球状”岩石是不乏见的。“球状”岩石最早为伯奇(Buch)所描述,以后一直为岩石学家所注意。对“球状”岩石中球体的成因,有各种各样的解释莱维森(Leveson)。凯斯勒(Kesler)用电子探针研究了球状安山岩中球体和基质的化学成分特点,并据基思(Keith)假说,推测了球体形成温度为900-1000℃,球体生长速度为10^-6厘米/秒。  相似文献   

Inventory of mangrove wetlands in the Pearl River Estuary of China using remote sensing     

LI Xia  YEH Anthony  LIU Kai  WANG Shugong 《地理学报》2006,16(2):155-164

Mangrove forests have important ecological functions in protecting the environment. However, the mangrove wetlands have been largely lost because of intensified human activities in the study area. Remote sensing can be conveniently used for the inventory of mangrove forests because field investigation is very difficult. In this study, a knowledge-based system is developed to retrieve spatio-temporal dynamics of mangrove wetlands using multi-temporal remote sensing data. Radar remote sensing data are also used to provide complementary information for the quantitative analysis of mangrove wetlands. Radar remote sensing is able to penetrate mangrove forests and obtain the trunk information about mangrove structures. The integration of radar remote sensing with optical remote sensing can significantly improve the accuracies of classifying mangrove wetland types and estimating wetland biomass.  相似文献   

The experimental study for the allocation of ground-sills downstream of check dams   总被引：2，自引：1，他引：1  

Bing-Shyan LIN  Chao-Hsien YEH  Hui-Pang LIEN 《国际泥沙研究》2008,23(1):28-43

The main purpose of this study is to understand the stabilizing effect of ground-sills on the riverbed through a series of flume model experiments. From results, although check dams have the ability to control upstream sediment transport, the mass energy produced by the free fall of the overtopping discharge still causes strong local scour downstream of the structure, and this scour leads to the instability of the check dam. Therefore, this study conducted model experiments on various types of serial ground-sills to determine the appropriate spacing to best protect the downstream bed. Based on the observations and analysis of channel geomorphology and sedimentation, this study concluded the following results： 1） Serial ground-sills reduces the sediment transport ability perfectly, especially under a mild channel gradient equipped with 2 4 times the average channel width interval. But for steep slopes, it is suggested that the proper spacing should be shortened to 1 2 times the average channel width. 2） Ground-sills can effectively protect the streambed from scouring under a suitable equipped condition and the concepts of guiding scour and riverbed inertia were used in the analysis of optimal ground-sill spacing.  相似文献   

遗传算法和GIS结合进行空间优化决策   总被引：15，自引：2，他引：13  

黎夏  叶嘉安 《地理学报》2004,59(5):745-753

资源的有效利用和管理往往涉及到空间的优化配置问题。例如需要在空间上确定n个设施的最佳位置。当选址问题涉及多个目标和不同的约束性条件时,就会变得十分复杂。利用一般的brute-force搜索方法无法对涉及高维数据的问题进行求解。利用遗传算法和GIS结合来解决复杂的空间优化配置问题,具有智能的搜索方法可以大大提高空间的搜索能力。在基于进化的优化过程中,根据GIS的空间数据来计算不同解决方案 (染色体) 的适应度。针对不同的应用目的,GIS可以给出不同的适应度函数。实验表明,所提出的方法比简单的搜索方法和退火算法有更大的优越性。该方法在处理复杂的空间优化问题有更好的表现。  相似文献   

DEPTH-INTEGRATED MODELING FOR AGGRADING/DEGRADING MOBILE CHANNELS I： MODEL DEVELOPMENT     

En-Tian LIN Chih-Tsung HSU Keh-Chia YEH 《国际泥沙研究》2006,21(4):281-293

1 INTRODUCTION The study of sediment transport in alluvial river is one of the most important fields in hydraulic engineering. Sediment transport has direct influence on the evolution of riverbeds, estuaries and coastlines, and, in turn, affects decision-making of flood control, operating rule of reservoir, design of hydraulic structure and many other aspects. Models with different orders of dimensions were presented in the literature, and most of them had common basis that they were formu…  相似文献