基于713雷达回波实施人影作业指挥的技术方法

文章介绍了利用VC编程软件实现对713天气雷达dBZ文件自动读取、平显高显自动关联、自动分块、自动跟踪、自动预警以及自动判断是否可以实施人影作业的技术方法。     

一种非凸包边界约束不规则三角网生成算法

数字高程模型(DEM)模拟的大多数地形区域是多种类型区域镶嵌而成的复合体,且子区域的边界一般为非凸多边形,即三角网受到边界的约束。而目前已有的各种Delaunay三角网构网算法生成的不规则三角网的边界都是区域内采样点集的凸包,不能表达复合区域和边界为非凸多边形的区域。本文作者对三角网扩张法作了扩展,使之能够在任意多边形所包围的区域内生成不规则三角网。扩展后的算法具有步骤简单、适合任意多边形边界内生成不规则三角网的优点,而且该算法可用于"分块"式生成数据量较大的三角网,同时保证各"分块"之间完整的邻接关系。     

土壤湿度对不规则起伏地表雷电垂直电场传播影响的研究

本文采用二维fractional Brown motion(f Bm)随机分形界面模拟不规则起伏地表,基于Longmire-Scott提出的土壤电参数等效模型(L-S模型),分析研究不规则起伏地表的土壤湿度对地闪回击垂直电场传播的影响。结果表明:(1)地表的不规则起伏程度主要会引起垂直电场峰值的衰减和上升沿时间的滞后。随着地表不规则起伏程度的增大,垂直电场峰值衰减越明显,且波形上升沿时间增长。(2)无论地表不规则程度如何,随着土壤湿度的增大,垂直电场的衰减反而减小。(3)总的来说,地表的不规则程度越大,土壤湿度越小,垂直电场的峰值衰减越大,波头上升沿时间越长。     

竖向不规则框架结构连续性倒塌分析

国内外学者利用非线性静力方法进行结构倒塌分析时,研究对象主要集中在规则的结构形式,而针对大量出现的造型独特的竖向不规则建筑的倒塌研究还相对较少。本文基于拆除构件法,利用SAP2000结构有限元软件,对竖向不规则多层框架结构进行了基于非线性静力Pushdown方法的抗连续性倒塌研究。分别研究了拆除同一结构中不同部位构件、不同层数塔楼结构中相同部位构件后剩余结构的承载力变化情况,研究结果表明：拆除竖向承重柱后的剩余结构承载力,随着上部塔楼层数的增加以及拆柱位置的上升而出现不同程度的降低;加强裙楼顶部水平向承重构件,可以使塔楼底部构件破坏后的剩余结构更好地发挥悬链线机制,并防止剩余结构发生无明显征兆的连续性倒塌。     

波流水槽模拟波浪技术的研究

介绍了实验室的造波机系统和造波特性及其在模型试验中的应用,并讨论了实验室内模拟海浪的检验标准及其方法。并对造波机应用前景进行讨论,对不规则波造波机进行物模试验具有一定的现实意义。     

Astrometry of near-earth objects using small telescopes

Currently, when a near-Earth object (NEO: any asteroid or comet approaching the terrestrial orbit about the Sun) is discovered, there is a distinct chance that it will be lost again due to the lack of suitable follow-up astrometry. The burgeoning international Spaceguard program — which has an aim of discovering and determining the orbits of all possible Earth-impactors so that calamitous collisions can be avoided-will make this problem more acute, as the discovery rate increases. When NEOs reach visual magnitudes brighter than 21, they may be observed with suitable CCD-equipped telescopes with apertures of one metre or less; in fact, even 0.25-m aperture instruments are now being employed to great effect in this regard. This means that in the present situation, countries or individuals having access to quite modest-sized and modest-priced equipment can make a real, valuable contribution to this international effort. When Spaceguard begins in earnest it will be vital that astronomers spread around the world, using small telescopes, take over the tracking of NEOs discovered by the large, expensive, search instruments. The Spaceguard project therefore represents an excellent opportunity for international collaboration, with scientists in developing nations being valuable contributors in a space program with real significance for all humankind. Presented at the UN/ESA Workshop on Basic Space Science: From Small Telescope to Space Mission, Colombo, Sri Lanka, 11–14 January 1996.

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Macroseismic evidence and site effects for the Lunigiana (Italy) 1995 Earthquake

On October 10, 1995, an M_L= 4.8 (ING) earthquake occurred in the region of Lunigiana (northwestern Italy). The shock was felt over a large area and produced significant damage. We performed a macroseismic survey and damage zonation and assessed a maximum intensity VII MCS in the epicentral area. The damage pattern, that we investigated in detail for some of the villages in the most heavily damaged area, emphasises the role of surface geology in amplifying the effects. Topographic effects and near-surface geology are largely responsible for broadening the damage area. Given the moderate size of the earthquake, many of the macroseismic observations, including rotations of objects and the propagation of visible waves in the ground, are suggestive of amplification phenomena.     

顾及地形的城市三维可视化方法研究

介绍了三维房屋重建与城市可视化方法研究和应用模块开发的初步成果。在一般二维不规则三角网的基础上,发展了有确定边界条件下的二维不规则三角网,通过对顾及地形的铅直墙面和不规则屋顶的分别构网和合成,形成建筑物的表面不规则三角网,消去共面条件下的公共边后,实现了顾及地形的的城市房屋重建。