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81.
中国地震台网数字化改造的进展   总被引:12,自引:0,他引:12       下载免费PDF全文
介绍了九五期间(1996~2000年)中国地震台网数字化改造的进展和首都圈数字地震台网(1999~2001年)的建设情况,重点介绍了国家数字地震台网、区域数字地震台网和流动数字地震台网的台站分布、仪器配备和主要任务.   相似文献   
82.
The advanced personal computer models, new storage media such as CD-ROMs, new authoring tools and especially the Internet will influence the production of learning software for photogrammetry. Some examples of learning programs are presented, including experience from the development and use of these programs in the education of land surveyors. They demonstrate the progress made over the years as well as the potential and possibilities of computer-assisted teaching and learning in photogrammetry.  相似文献   
83.
杨燕  纪立人 《大气科学》1997,21(5):533-534
用数字滤波方法对观测资料序列进行处理,得到初始场用于T42L9全球谱模式的月预报,以去除误差增长较快的高频扰动对低频过程的影响,并且利用多时刻的观测资料提取低频过程的信息。对冬季和夏季两个不同个例进行了实例,并比较了取不同长度的观测序列,截取不同周期的过程作为初值对预报效果的影响。结果说明,经过滤波后对低频分量和平均场的预报都有显著的改进。而且对于较长时效的预报,应保留更低频的过程(比如10d以上  相似文献   
84.
通过计算机对数字地震台网产出的大动态、高分辨率、高精度的地震波形数据进行的实时采集跟踪分析,发现了有些台站大震前地脉动波形的周期和幅度有明显异常变化,探索大震前地脉动变化的特征和规律,将为区域性地震预报研究开辟一条新的途径。  相似文献   
85.
陕西中南部的视应力场研究   总被引:2,自引:1,他引:2       下载免费PDF全文
利用西安数字地震台网的宽频带数字地震记录,计算了陕西中、南部地震的视应力水平,并讨论了泾阳5.2级地震前后地震视应力的时间变化特征及视应力与震级的关系。  相似文献   
86.
87.
The introduction of digital cameras for aerial survey photography and use of scanners with processed aerial film present a number of technical questions concerning the way photography is to be acquired in the future. Among the questions to be addressed are the comparative metric properties of images acquired by each system and the associated image quality characteristics. The new digital camera systems will require very careful appraisal, using well-established methods of assessing metric quality already available to survey organisations. The questions concerning image quality are more difficult to answer, as they require very specialised instrumentation if measurements are to be made directly in practice. Over the course of the past several decades a more analytical approach to assessing image quality has emerged, and one that may be used by individuals. The method is particularly effective where information on the micro-image characteristics of products is made available by the manufacturers concerned. An outline is given of some considerations that need to be taken into account when using an analytical approach, with references given for further reading.  相似文献   
88.
Sanyal  Joy  Lu  X. X. 《Natural Hazards》2004,33(2):283-301
The conventional means to record hydrological parameters of aflood often fail to record an extreme event. Remote sensingtechnology along with geographic information system (GIS)has become the key tool for flood monitoring in recent years.Development in this field has evolved from optical to radarremote sensing, which has provided all weather capabilitycompared to the optical sensors for the purpose of flood mapping.The central focus in this field revolves around delineation of floodzones and preparation of flood hazard maps for the vulnerable areas.In this exercise flood depth is considered crucial for flood hazardmapping and a digital elevation model (DEM) is considered to bethe most effective means to estimate flood depth from remotelysensed or hydrological data. In a flat terrain accuracy of floodestimation depends primarily on the resolution of the DEM. Riverflooding in the developing countries of monsoon Asia is very acutebecause of their heavy dependence on agriculture but any floodestimation or hazard mapping attempt in this region is handicappedby poor availability of high resolution DEMs. This paper presents areview of application of remote sensing and GIS in flood managementwith particular focus on the developing countries of Asia.  相似文献   
89.
随着Internet技术的飞速发展,以及对数字地球概念的深入探讨,WebGIS已经是GIS发展的必然趋势。本文在WebGIS技术基础上,以中国矿业大学为例,论述了基于MapObjects IMS及VB6.0语言的数字校园网上发布的实现过程。  相似文献   
90.
High‐resolution historical (1942) and recent (1994) digital terrain models were derived from aerial photographs along the Big Sur coastline in central California to measure the long‐term volume of material that enters the nearshore environment. During the 52‐year measurement time period, an average of 21 000 ± 3100 m3 km?1 a?1 of material was eroded from nine study sections distributed along the coast, with a low yield of 1000 ± 240 m3 km?1 a?1 and a high of 46 700 ± 7300 m3 km?1 a?1. The results compare well with known volumes from several deep‐seated landslides in the area and suggest that the processes by which material is delivered to the coast are episodic in nature. In addition, a number of parameters are investigated to determine what influences the substantial variation in yield along the coast. It is found that the magnitude of regional coastal landslide sediment yield is primarily related to the physical strength of the slope‐forming material. Coastal Highway 1 runs along the lower portion of the slope along this stretch of coastline, and winter storms frequently damage the highway. The California Department of Transportation is responsible for maintaining this scenic highway while minimizing the impacts to the coastal ecosystems that are part of the Monterey Bay National Marine Sanctuary. This study provides environmental managers with critical background data on the volumes of material that historically enter the nearshore from landslides, as well as demonstrating the application of deriving historical digital terrain data to model landscape evolution. Published in 2005 by John Wiley & Sons, Ltd.  相似文献   
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