基于数字摄影测量的GIS数据获取

作为一种重要的数据获取的手段，数字摄影测量技术逐渐得到了GIS工作者的重视。本文的作者着重探讨了数字摄影测量作为获取GIS数据的手段所具有的优势，同时结合自己在超高压输电线路数字化运行维护管理系统中的开发工作，具体介绍了一种用数字摄影测量获取GIS数据的方法。     

乾安地区盐碱地显热通量的测量

文中给出了用大孔径闪烁仪在 2 0 0 0年生长季观测到的盐碱地区显热通量的主要结果 ,并初步计算了当地的水热平衡状况。结果表明 :乾安盐碱地区显热通量占净辐射量的百分比在干旱、非生长季达到 6 5 % ,在多雨、植被生长季仅为 11% ;显热通量因降水而明显降低 ,幅度与降水强度有关 ,反映了当地的气候和土壤特征。文中还把LAS的测量结果与传统的梯度法作了比较 ,结果基本一致。     

青藏高原地面-对流层系统的能量收支

利用CCM3中的辐射模式CRM，计算了1月和7月地－气系统、地面－对流层系统和地面辐射能收支，研究了青藏高原地面－对流层系统辐射能收支的冬、夏季节特征及其与地面和地－气系统辐射能收支的关系，并与东部平原地区和高原北侧干旱地区比较。文中还讨论了云和高原冬季地面积雪对辐射能收支的影响，比较了大气辐射加热和地面感热通量对夏季高原对流层大气加热的贡献。     

青藏高原近地面层微气象学特征

利用1998年5月-7月在改则、当雄和昌都三测站获得的近地面层气象要素变化的观测资料，分析了青藏高原近地面层风速、温度和湿度日变化特征及廓线规律，发现高原近地面层微气象学特征具有自己的特点；同时还讨论了高原近地面层白天出现的逆湿现象。     

根据Dobson和TOMS资料分析北京和昆明大气臭氧总量变化特征

用约２０年 Ｄｏｂｓｏｎ和ＴＯＭＳ资料来分析北京（３９.９３°Ｎ，１１６.４０°Ｅ）和昆明 （２５.０２°Ｎ，１０２．６８°）两地大气臭氧总量的变化特征，结果表明：（１）在１９７９－２０００年间北京大气臭氧长期变化趋势是－０．６４２ ＤＵ／年，而昆明在１９８０－２０００年间的趋势是－０.００９ ＤＵ／年；（２）北京和昆明两地大气臭氧都有很强的季节内变化（尤其冬季更强），与季节性变化强度相当；（３）在北京和昆明，由记录较短的大气臭氧资料分析得到的长期变化趋势，与较长记录得到的结果有显著差异；（４）在北京（中纬度）和昆明（低纬度）大气臭氧都有显著的准两年振荡信号；（５）两个站点大气臭氧的年际变化主要由长期趋势项和准两年振荡信号组成；（６）Ｄｏｂｓｏｎ仪测量得到的臭氧总量与ＴＯＭＳ资料非常一致。     

The thermodynamic influence of subgrid orography in a global climate model

Assessments of the impacts of climate change typically require information at scales of 10 km or less. Such a resolution in global climate simulations is unlikely for at least two decades. We have developed an alternative to explicit resolution that provides a framework for meeting the needs of climate change impact assessment much sooner. We have applied to a global climate model a physically based subgrid-scale treatment of the influence of orography on temperature, clouds, precipitation, and land surface hydrology. The treatment represents subgrid variations in surface elevation in terms of fractional area distributions of discrete elevation classes. For each class it calculates the height rise/descent of air parcels traveling through the grid cell, and applies the influence of the rise/descent to the temperature and humidity profiles of the elevation class. Cloud, radiative, and surface processes are calculated separately for each elevation class using the same physical parametrizations used by the model without the subgrid orography parametrization. The simulated climate fields for each elevation class can then be distributed in post-processing according to the spatial distribution of surface elevation within each grid cell. Parallel 10-year simulations with and without the subgrid treatment have been performed. The simulated temperature, precipitation and snow water are mapped to 2.5-minute (~5 km) resolution and compared with gridded analyses of station measurements. The simulation with the subgrid scheme produces a much more realistic distribution of snow water and significantly more realistic distributions of temperature and precipitation than the simulation without the subgrid scheme. Moreover, the 250-km grid cell means of most other fields are virtually unchanged by the subgrid scheme. This suggests that the tuning of the climate model without the subgrid scheme is also applicable to the model with the scheme.     

矿产勘查与评估的统计地球化学方法

统计地球化学在矿产勘查与评估中的应用，主要包括采术规则，临界品位计算，资源量／储量公式，边界品位确定，网度判别，矿床经济分类以及矿床开发风险等内容。     

西南某电站右岸倾坡内夹泥裂隙成因探讨

西南某拟建大型水电站的右岸岩体中存在倾向坡内的夹泥裂隙，通过对其的发育情况以及所处的地质环境进行系统的研究和认真剖析，认为该区内的倾坡内夹泥裂隙的成因并非正常卸荷引起，而是在构造的基础上，穹隆挽近期隆起的结果，为右岸坝肩稳定性评价提供了可靠的依据。     

一种新的储层孔隙成因类型--石英溶解型次生孔隙

石英作为碎屑岩储层中的一种难溶组分,普遍认为它和次生孔隙的形成关系不十分密切。研究认为泌阳凹陷核桃园组储层中的碎屑石英颗粒存在明显的溶解现象,并形成以石英直接溶解型孔隙为主的储集空间特征。石英颗粒被溶解的部分在薄片中所占的范围为 2 %～ 7%者常见,高者达 8%以上,在总孔隙中所占的相对含量也多数在10 %～ 35 %之间,早成岩B期是其最主要形成期。石英溶解型次生孔隙的大量存在为碎屑岩储层中SiO₂ 胶结物及次生孔隙成因等问题的解释以及储层预测和评价提供了新的可能性。     

Tests on low‐ductility RC frames under high‐ and low‐frequency excitations

The response of low‐ductility reinforced concrete (RC) frames, designed typically for a non‐seismic region, subjected to two frequencies of base excitations is studied. Five half‐scaled, two‐bay, two‐storey, RC frames, each approximately 5 m wide by 3.3 m high, were subjected to both horizontal and/or vertical base excitations with a frequency of 40 Hz as well as a lower frequency of about 4 Hz (close to the fundamental frequency) using a shake table. The imposed acceleration amplitude ranged from 0.2 to 1.2g. The test results showed that the response characteristics of the structures differed under high‐ and low‐frequency excitations. The frames were able to sustain high‐frequency excitations without damage but were inadequate for low‐frequency excitations, even though the frames exhibited some ductility. Linear‐elastic time‐history analysis can predict reasonably well the structural response under high‐frequency excitations. As the frames were not designed for seismic loads, the reinforcement detailing may not have been adequate, based on the crack pattern observed. The effect of vertical excitation can cause significant additional forces in the columns and moment reversals in the beams. The ‘strong‐column, weak‐beam’ approach for lateral load RC frame design is supported by experimental observations. Copyright © 2001 John Wiley & Sons, Ltd.