加解密技术在我国新一代气象卫星数据传输中的应用     

崔鹏 杨军施进明  王素娟 《气象科技》2006,34(2):233-236

我国新一代气象卫星探测资料种类繁多,资料发送方式多种多样,为了保证某种探测资料在特定环境下的授权使用,在数据传输过程中采用了加密和解密技术。在星上,对将要传输的数据通过分配的加密密钥进行加密处理;在地面,只对授权用户分配解密密钥,保证授权用户可以对接收到的数据进行解密处理,把数据恢复为可用状态。本文介绍了应用在新一代气象卫星数据传输过程中的加解密算法,并讲述了应用软件实现地面解密的过程。  相似文献   

Recent Advances and Difficulties of Infrasonic Wave Investigation in the Ionosphere     

Valeriy M. Krasnov  Yana V. Drobzheva  Jan Laštovička 《Surveys in Geophysics》2006,27(2):169-209

Acoustic waves have a remarkable ability to transfer energy from the ground up to the uppermost layers of the atmosphere. On the ground, there are many permanent sources of infrasound, and also pulsed and/or sporadic sources (e.g., sea waves, infrasonic and sonic noise of cities, lightning, earthquakes, explosions, etc.). The infrasonic waves carry away the major part of their energy upwards through the atmosphere. What are the consequences of the upward energy transfer? What heights of the atmosphere are supplied by energy from various sources of an infrasonic wave? In most cases, the answers to these questions are not well known at present. The only opportunity to monitor the propagation of an infrasonic wave to high altitudes is to watch for its influence on the ionospheric plasma. Unfortunately, most of standard equipment for ionospheric sounding, as a rule, cannot detect plasma fluctuations in the infrasonic range. Besides, the form of an infrasonic wave strongly varies during propagation due to nonlinear effects. However, the development of the Doppler method of radiosounding of the ionosphere has enabled progress to be made. Simultaneously, the ionospheric method for sensing aboveground and underground explosions has been developed. Its main advantage is the remote observation of an explosion in the near field zone by means of short radio waves, i.e., the radio sounding of the ionosphere directly above the explosion. The theory of propagation of an acoustic pulse produced by an explosion on the ground up to ionospheric heights has been developed better than the theory for other sources, and has been quantitatively confirmed by experiments. A review of some advances in the area of infrasound investigations at ionospheric heights is given and some current problems are presented.  相似文献   

前期中高纬大气环流异常与我国汛期雨带类型关系的研究   总被引：1，自引：2，他引：1  

严华生  杨素雨  胡娟  陈建刚 《大气科学》2006,30(2):285-292

使用国家气候中心提供的1951～2002年北半球500 hPa高度上的月平均格点资料,对前期(1～5月)中高纬大气环流的异常与中国汛期雨带类型分布的关系进行了研究.结果表明,冬季(1～2月)500hPa环流的时空演变与中国汛期雨带类型分布有明显的相关,春季(3～5月)是转换季节,与雨带类型分布的关系不如冬季密切.尽管不同的雨带类型对应不同的高度距平合成场,但各雨型的高度距平之间只存在三个显著性差异区,且各雨带类型的西风指数显著性差异区与同期高度距平合成场的显著性差异区的经度范围一致.1、2月第一与第二显著  相似文献   

会泽铅锌矿床的地质特征及成因探讨   总被引：2，自引：0，他引：2  

严鑫熔  李元 《地下水》2006,28(6):123-125

本文通过对矿床地质特征的综合分析研究,讨论了成矿的地质环境、物质来源、矿床形成的物理化学条件,建立了矿床的成矿模式.  相似文献   

放坡填筑方法在防治大型岸坡中的应用     

温小刚 《贵州地质》2006,23(2):127-131

本文结合湖北省三峡库区宜昌市夷陵区太平溪集镇岸坡防治工程实例,应用了放坡填筑方法治理大型岸坡。主要介绍了放坡填筑治理大型岸坡的施工方法、关键措施,以及常见问题的处理方法,为以后类似工程提供了应用和施工实例。  相似文献   

Power law distributions of seismic rates     

A. Saichev  D. Sornette   《Tectonophysics》2007,431(1-4):7

We report an empirical determination of the probability density functions P_data(r) of the number r of earthquakes in finite space–time windows for the California catalog for different space (5 × 5 to 50 × 50 km²) and time intervals (0.1 to 1000 days). The data can be represented by asymptotic power law tails together with several cross-overs reasonably explained by one of the most used reference model in seismology (ETAS), which assumes that each earthquake can trigger other earthquakes according to complex cascades. These results are useful to constrain the physics of earthquakes and to estimate the performance of forecasting models of seismicity.  相似文献   

长江中上游土壤自然侵蚀量及其估算方法   总被引：7，自引：2，他引：7  

景可  张信宝 《地理研究》2007,26(1):67-74

首先阐述了土壤侵蚀可分为自然侵蚀和人为加速侵蚀,自然侵蚀是自地球形成以来就普遍存在的一种自然现象;继而从夷平面、河流阶地、沉积盆地等侵蚀和堆积地貌形迹论述了第四纪以来长江中上游土壤自然侵蚀存在的佐证事实;在此基础上,依据侵蚀沉积相关原理,利用沉积物的厚度、面积和沉积时段分别计算了洞庭湖流域、鄱阳湖流域和古云梦泽流域全新世以来的自然侵蚀量,它们分别为264.2t/km² · a、 312.5t/km² · a和297.0t/km² · a;同时,本文还辅以川西和三峡地区的对比实验小区资料,现代自然侵蚀量分别为342.0t/km² · a、 75~270t/km² · a佐证历史自然侵蚀量。长江上中游区域的自然侵蚀量介于264.0t/km² · a ~342.0t/km² · a之间。流域平均自然侵蚀量是现代侵蚀量的50%~60%之间;本研究成果有助于对长江中上游现代土壤侵蚀的属性、演变过程有一个科学的认识;同时可为生态保护、环境友好建设目标提供背景参照物。  相似文献   

关于重点开发区域主体功能定位的思考——以河南省为例     

陈佳丽 《地域研究与开发》2007,26(5):48-50

论述了主体功能区划在国土空间布局上落实科学发展观的重大战略意义,认为国家重点开发区域向中部地区转移是一次全局性的战略抉择.着重阐明了重点开发区域的主体功能定位,即:通过推进城镇化、工业化,实现人口与经济的协调聚集,培育促进全国经济长期持续又好又快发展的新的增长区域,提出了推进形成重点开发区域的财政、投资、产业、土地及人口管理政策,为政府决策提供参考依据.  相似文献   

HEAVY METAL POLLUTION IN SURFACE SEDIMENTS COLLECTED FROM DRAINAGES RECEIVING DIFFERENT ANTHROPOGENIC SOURCES FROM PENINSULAR MALAYSIA     

Chee Kong Yap  Bin Huan Pang  Yoong Inn Hoo  Soon Guan Tan 《湿地科学》2007,5(2):97-104

Surface drainage sediments were collected, between January and April in 2005, from 6 sampling sites in Peninsular Malaysia suspected to have received different anthropogenic sources. These drainages included sites near a petrochemical plant, an electronic factory, a metal factory and 2 townships in addition to a relatively unpolluted site (a reference site). Based on the aqua-regia method, the metal concentrations for all the sampling sites except for the agricultural site (reference site) at Sg. Benut were between 60.92-1 019 μg/g dry weight for copper (Cu), 65.32-1 266.6μg/g dry weight for plumbum (Pb), 1.46-15.93 μg/g dry weight for cadmium (Cd), 330.10-484.14 μg/g dry weight for zinc (Zn) and 47.03-120.90 μg/g dry weight for nickel (Ni). All of these ranges were significantly (p< 0.05) higher than those (Cu: 8.77 μg/g; Pb: 57.42 μg/g; Cd: 0.96 μg/g; Zn: 68.21 μg/g; and Ni: 17.87 μg/g) of the reference site at Sg. Benut that only received agricultural disposal. The concentrations for the 5 metals from all the sites (except for the reference site) were higher than the Sediment Quality Values for Hong Kong by Chapman et al (1999) for the 5 metals. Based on the sequential extraction technique, 3 geochemical fractions [easily, freely leachable and exchangeable (EFLE), acid-reducible and oxidisable-organic] were also useful in identifying these polluted sites. The elevated metal concentrations found in the sediments might be related to point sources of industrial effluent and urban waste. Hence, the results emphasized the necessity for the treatment of effluents into this drainage area. As part of the effort to control illegal discharges and dumping into drainages, public awareness should be enhanced.  相似文献   

上海地区地质灾害危险性评估关键技术问题研究   总被引：13，自引：2，他引：13  

龚士良 《中国地质灾害与防治学报》2007,18(3):92-96

"建设项目地质灾害危险性评估技术规程"即将成为上海市工程建设规范。该规程总结了以往评估实践,细化和完善了具体技术细则,强化了指导性和可操作性。介绍了上海地区确定的地面沉降、地基变形、边坡失稳、砂土液化、水土突涌、岸带冲淤、浅层天然气害、水土污染等8个评估灾种的界定、地质环境条件复杂程度的分类要素及划分标准、建设项目重要性的具体划分、评估范围的确定、地质灾害危险性分级分区原则、拟建场地建设适宜性评价准则等灾评实践及规程编制中的关键技术问题。  相似文献