川藏公路地质环境与整治改建方案的思考

川藏公路由于地质环境复杂、建设标准低、后遗病害多,抗灾能力差,泥石流、滑坡、山崩、雪害、水毁等自然灾害频繁发生,公路阻车断道严重。国家投入巨资进行整治改建,并取得了明显的效果,但由于自然环境特殊、影响因素复杂,许多特大型、大型工程地质病害问题还没有可行、可靠的解决方案。本文通过分析川藏公路沿线的地质环境和灾害特点,总结历年整治改建和经验的教训,提出川藏公路建设的途径、可能达到的目标和应采用的原则。     

高分辨率FMS成像测井资料在科学大洋钻探中的应用

FMS地层微电阻率扫描成像测井技术诞生于1986年,1989年首次在大洋钻探中获得应用。它采用纽扣电极阵列沿井壁纵向扫描方式采集地层的电阻率信息,经过适当的数字和图像处理后转化为井壁地层的二维微电阻率图像。FMS资料具有分辨率高(理论分辨率为5 mm)、连续原位测量及定向性等特点,是科学大洋钻探中岩芯地质分析方法的重要补充,具有其他地球物理方法难以替代的作用。从岩芯归位和定向、岩性岩相识别及地层剖面重建、沉积构造和古流方向分析、地层旋回性与古气候周期分析、浊积层厚度统计分析、构造和应力场分析及洋壳研究等7个方面对FMS在科学大洋钻探中的应用现状进行综述,对目前FMS成像测井资料应用中存在的问题及发展方向进行分析,包括利用率不高、定量分析成果欠缺、研究深度和广度有待拓展等。     

Reconstruction of ion and electron density profiles from space-based measurements of the upper electron content

Presented is a new method for retrieving the topside electron density distribution from space-based observations of the total electron content. By assuming an adequate topside density distribution, the profile reconstruction technique utilizes ionosonde and oxygen-hydrogen ion transition level measurements for uniquely determining the unknown ion scale heights and the corresponding ion and electron density profiles. The method is tested on actual measurements from the CHAMP satellite. Important applications are envisaged, such as developing and evaluating empirical and theoretical ionosphere-plasmasphere models.     

Automatic representation and reconstruction of DBM from LiDAR data using Recursive Minimum Bounding Rectangle

Three-dimensional building models are important for various applications, such as disaster management and urban planning. The development of laser scanning sensor technologies has resulted in many different approaches for efficient building model generation using LiDAR data. Despite this effort, generation of these models lacks economical and reliable techniques that fully exploit the advantage of LiDAR data. Therefore, this research aims to develop a framework for fully-automated building model generation by integrating data-driven and model-driven methods using LiDAR datasets.The building model generation starts by employing LiDAR data for building detection and approximate boundary determination. The generated building boundaries are then integrated into a model-based processing strategy because LiDAR derived planes show irregular boundaries due to the nature of LiDAR point acquisition. The focus of the research is generating models for the buildings with right-angled-corners, which can be described with a collection of rectangles under the assumption that the majority of the buildings in urban areas belong to this category. Therefore, by applying the Minimum Bounding Rectangle (MBR) algorithm recursively, the LiDAR boundaries are decomposed into sets of rectangles for further processing. At the same time, the quality of the MBRs is examined to verify that the buildings, from which the boundaries are generated, are buildings with right-angled-corners. The parameters that define the model primitives are adjusted through a model-based boundary fitting procedure using LiDAR boundaries. The level of details in the final Digital Building Model is based on the number of recursions during the MBR processing, which in turn are determined by the LiDAR point density. The model-based boundary fitting improves the quality of the generated boundaries and as seen in experimental results, the quality depends on the average LiDAR point spacing. This research thus develops an approach which not only automates the building model generation, but also achieves the best accuracy of the model while utilizing only LiDAR data.     

日本3月11日大地震灾情及震后重建困局

文章通过收集日本3月11日大地震的资料,分析汇总其灾害情况、复兴重建情况以及次生灾害福岛核辐射为日本社会和公众带来的灾难及影响,为日后此类重大地震事件的灾害评估及重建提供一定的借鉴作用。     

Long-term Reconstructions and Simulations of the Hydrological Cycle in the Inland Rivers,Arid China: A Case Study of the Shiyang River Drainage Basin

Hydrological cycles of inland rivers are highlighted in paleoclimate studies of arid regions. A great number of studies have been published in this regard, but most of the studies have mainly used climate proxies to reconstruct the evolution of paleoclimate and paleoenvironment, and there have been little long-term simulation and reconstruction experiments. Concerning this issue, we systematically carried out the long-term reconstruction and simulation experiments of hydrological cycle based on paleoenvironment records of the Shiyang River drainage basin with a lot of methods such as paleoclimate simulations, the Holocene monsoon simulations, lake water and energy balance model and quantitative reconstruction of paleo-precipitation and paleo-runoff. The results showed that the simulation results had a good consistency with the reconstruction results, indicating that mid-Holocene was “climatic optimum” in the Holocene. This research provided a new perspective for reconstruction and simulation studies of climate change in arid areas.     

锥束重建的Smith—Grangeat方法的分析

ＣＴ机、ＳＰＥＣＴ及ＰＥＴ等医疗设备是当前重要的医疗诊断工具，但这些设备都跟某些射互有关，当放射性元素衰变而发射某种射线时，如果它们在４立体角范围内是等概率分布的，则扇形采集比在上方向上有集的效率提高了许多。     

The influence of Asian summer monsoon variability on the water balance of a Tibetan lake

Past water-balance changes in Tibetan lakes are generally attributed to changes in the strength of the summer monsoon. However, the water balance of a lake reflects many different water fluxes, which are controlled by many climatic and hydrologic processes. In this research, weather data and evaporation models are used to determine the climatic cause of a recent water-balance change in Ahung Co, a lake in central Tibet. Between 1995 and 2001, lake level rose at least 20 cm and the lake began to overflow. Results indicate that an increase in summer monsoon precipitation over the lake and drainage basin is responsible for the rise in lake level. Stronger monsoon conditions between 1995 and 2001 also led to decreased lake evaporation and basin evapotranspiration due to increased clouds and humidity. This contributed to the rise in lake level, but to a much smaller extent than the increase in monsoon precipitation. Lake evaporation during the spring and fall was also reduced between 1995 and 2001 due to longer lasting ice cover. Variations in ice cover play a small role in the overall water balance of Ahung Co, however, because the lake area is small compared to the drainage basin area. If these results hold true for the past, water-balance fluctuations inferred from the geochemistry of sediments from Ahung Co provide a record of variations in monsoon precipitation during the Holocene.     

非均匀有耗媒质层介电常数剖面和电导率剖面的重建

本文从微波网络的观点出发，在高频近似下，导出了非均匀有耗媒质在ＴＥ波和ＴＭ波入射时反射系数的近似解析表达式，进而获得重建媒质介电常数剖面和电导率剖面的解析反演公式。研究表明，当媒质的损耗为零时，本文公式退化成无耗媒质的重建公式（１－４）。重建实例证明了本文方法的有效性。     

三维体数据可视化技术

本文对体数据、可视化技术发展的历史和现状进行了综述，介绍了体数据显示的主要过程，全面地分析了各种算法和技术的特点。同时介绍我们所提出的一种体数据显示算法。最后，我们将讨论体数据可视化目前存在的问题及其发展趋势。