有耗媒质中脉冲响应的研究   总被引：1，自引：0，他引：1  

沈飚  于东海 《物探化探计算技术》1996,18(4):304-309

本文详细论述了一维有耗媒质中脉冲响应的正演理论及其模拟技术。深入研究了导电率、介电常数对脉冲响应的影响。以平面脉冲电磁波在一维介质中的传播理论为基础，编制脉冲响应的仿真模拟软件。最后，用实际模型验证了该模拟技术的正确性和可靠性。  相似文献   

土壤—植物—大气系统水分运行的界面过程研究   总被引：62，自引：1，他引：62  

刘昌明 《地理学报》1997,52(4):366-373

本文从水文循环的微观角度出发，针对大田土壤－大气系统中的水分运行与转化，研究了ＳＰＡＣ各界面上水分与能量的交换过程，旨在通过各界面上水分运行与生态环境因子相互作用关系，探索各界面水分、能量通量的计算与人工调控的可能途径，为农业节水提供理论依据。  相似文献   

利用太阳直射光谱遥感大气柱水汽总量的研究     

李放  吕达仁  刘锦丽 《遥感学报》1996,(4)

太阳光谱仪测得的直接辐射光谱含有大气水汽含量的信息。本文提出一种用太阳直射光谱反演大气柱水汽总量的方法。采用分子吸收的随机模式，而不是通常的Ｂｏｕｇｕｅｒ定理，处理水汽吸收，故更为合理。选取水汽的α，β和ρστ吸收带逐次扣除，联合订正，给出水汽含量。并与探空资料结果做了对比，有较好的一致性。  相似文献   

地面沉降研究的新进展与面临的新问题   总被引：39，自引：0，他引：39  

刘毅 《地学前缘》2001,8(2):273-278

通过国内外地面沉降研究历史概述 ,介绍了多方面的地面沉降原因。由于地下支撑物的移动导致地面标高损失是目前对地面沉降概念或原理的最新概括和总结。文章从监测技术、信息系统、图件编制、预测计算、损失评估和防治措施等方面概括了中国近年来地面沉降研究取得的新进展。同时提出淤泥质软土沉降问题、深部土层沉降问题、工程性沉降问题、长江三角洲地面沉降的严重性和系统性问题、地面沉降引起的全国性防汛能力降低问题和干涉合成孔径雷达 (InSAR)探测技术是中国当前地面沉降研究面临的新问题。最后指出 ,在中国城市化和工业化高速发展的 2 1世纪上半叶 ,中国东部的地面沉降问题将更大、更多、更复杂 ,需要认真规划和控制。  相似文献   

基于非线性理论的大气环境质量预测与评价     

徐辉  陈少华 《华东地质学院学报》2001,24(4):357-360

大气环境质量的预测和评价是一个典型的多变量和非线性问题。根据大气环境系统的性质，运用灰色系统理论和模糊数学理论建立大气环境质量预测和评价 的数学模型，通过对江西省抚州市环保局提供的实测数据进行科学计算，得到令人满意的结果，有较好的实用价值。  相似文献   

Pond biodiversity and habitat loss in the UK   总被引：2，自引：0，他引：2  

P J Wood  M T Greenwood  M D Agnew 《Area》2003,35(2):206-216

Ponds are common landscape features but have been poorly studied compared to other freshwater habitats in the UK, despite their high frequency of occurrence. In the last century, many ponds have been lost and those that remain face increasing pressure due to agricultural land drainage, pollution and urban development. However, ponds provide important habitats for diverse floral and faunal communities, including a number of rare taxa of conservation interest. This paper examines the biodiversity and wider environmental value of ponds, with particular reference to the aquatic invertebrate and amphibian communities they support, and the adverse impact of anthropogenic activity on their aquatic habitats.  相似文献   

Loss estimation: a powerful tool for risk assessment and mitigation     

F. Bendimerad   《Soil Dynamics and Earthquake Engineering》2001,21(5)

Earlier loss estimation studies were limited to investigating particular scenarios and were carried out by highly specialized experts. Today, loss estimation techniques are translated into efficient software applications that are accessible by a large constituency of end-users. These techniques offer a high level of analysis sophistication and enable users to perform various ‘if–then’ scenarios to study the sensitivity of the results, to develop a better understanding of the outcomes and to gain insight on the consequences of the findings and decisions. Functionality of loss estimation models has improved significantly due to advances in information technology such as the introduction of Geographical Information Systems (GIS). GIS allows for easy display of input and output (in standard reports and maps) providing a critical functionality for communication of outcomes to emergency planners and decision-makers.  相似文献   

2000年全世界地震灾害综述     

李卫平  黄瑾 《国际地震动态》2001,(6):12-15

2000年全世界地震活动水平略高于往年，但地震灾情很轻，地震死亡人数总计240人，伤3096人，经济损失约3亿美元，2000年印度尼西亚是地震灾害最严重的国家。  相似文献   

2001年上半年全世界地震灾情综述     

赵荣国  王科英 《国际地震动态》2001,(9):17-20

2001年1－6月全世界发生的较重大灾害地震共计8次，地震共计造成17759人死亡，953人失踪，15．9万人受伤，经济损失约163．3亿美元。重大灾害地震发生在印度。  相似文献   

A new procedure to estimate the RUSLE EI₃₀ index, based on monthly rainfall data and applied to the Algarve region, Portugal     

Nuno de Santos Loureiro  Miguel de Azevedo Coutinho 《Journal of Hydrology》2001,250(1-4):12-18

One of the best indicators of the potential erosion risks is the rainfall–runoff erosivity factor (R) of the revised universal soil loss equation (RUSLE). Frequently, however, there is not enough data available to compute the R value, and other parameters, such as the modified Fournier index (F_mod), are used instead. But RUSLE is less effective if only the alternative procedures exist. One of the major discrepancies between R and the alternative parameters is time resolution: individual storms are used to calculate R while monthly averages over the year are used to calculate F_mod.

In this study, a multiple linear regression (r²=0.89) involving monthly EI₃₀, monthly rainfall for days with ≥10.0 mm and monthly number of days with rainfall ≥10.0 mm, for the Algarve region, is presented. Twenty-seven years of monthly rainfall erosivity values were computed for the 32 standard daily-read raingauge stations of the Algarve region.  相似文献