水流冲刷沉积物生成泥石流的条件及运动规律的试验研究   总被引：6，自引：0，他引：6  

王姚印  张新玉 《地理学报》1989,44(3):291-301

在铺满卵石的陡槽上释放不同浓度、不同流量的泥浆或清水，观测卵石在泥浆流作用下的运动，研究泥石流的形成条件和运动规律。试验结果表明，当K（=rqJ）大于某临界值K_c时就会发生泥石流，但这个临界值K_c随波相泥浆浓度而变。泥石流龙头由大卵石组成，在不断摩擦和碰撞中翻滚着推进，消耗大量动能，同时控制着后续流不离散。后续流液相流速显著大于龙头，不断把能量输送到龙头，维持龙头运动。大卵石在运动中受到液相流的推动力较大，而受到的碰撞阻力较小，比龙头运动的快。因而大卵石逐渐集中于龙头。  相似文献   

空间太阳望远镜高速数据传输系统     

耿立红 《天文研究与技术》2002,(1)

“空间太阳望远镜”是中国的一项非常重要的天文卫星计划。卫星上将搭载 5个有效载荷 ,在可见光、远紫外、硬X射线、软X射线、Hα和射电波段同时观测太阳 ,其中的主光学望远镜口径达 1m。各有效载荷的CCD器件和其它敏感器件每天采集的科学数据量经过预处理后达 50Gbytes,再由数据压缩系统压缩至 8Gbytes,并储存在海量存储器中。如此庞大的数据量要求空间太阳望远镜的科学数据传输系统以高达 60Mbps的码速率向地面站传送。本文所有的工作均围绕着空间太阳望远镜高速数据传输系统展开 :1 .根据空间太阳望远镜的需求 ,综合研究、分析了它的科学数据传输系统的性能指标和特点 ,并作总体的方案设计 ;2 .设计开发了科学数据传输系统的信道编码和信道解码单元。信道编码单元将把海量存储器中的数据转换为适于QPSK射频调制格式化的串行数据流 ,信道解码单元实现相反的过程 ,文中详细给出了信道编码系统的原理、方法和实验结果。设计中引入了新的设计思想和方法 ,通信协议与现有地面站兼容 ;3 .完成了信道编码、解码环路的地面试验 ,结果表明信道编码、解码系统的技术指标完全符合空间太阳望远镜的要求。在理想无噪声条件下 ,闭环试验数据传输结果无误码 ,数据传输率达 60Mbps,是目前国内科学数据传输系统码速率  相似文献   

一种无线数据传输接口及控制装置     

陆斌  李景彬 《成都信息工程学院学报》1990,(Z1)

本文介绍一种无线数据传接口及控制装置。装置中采用计算机软件实现串—并、并—串变换及频率调制、其硬件成本低廉,工作可靠,可用于速率为50、300、600或1200bps的数传通信。  相似文献   

Characterisation of Soot Emitted by Domestic Heating,Aircraft and Cars Using Diesel or Biodiesel   总被引：1，自引：0，他引：1  

Anne?Smekens  Ricardo?Henrique?Moreton?Godoi  Patrick?Berghmans  René?Van?GriekenEmail author 《Journal of Atmospheric Chemistry》2005,52(1):45-62

The characterisation of aggregates, like soot, firstly requires the determination of the size distribution of the primary particles. The primary particle size of combustion generated aggregates depends upon the combustion environment and the formation conditions, such as temperature, pressure and fuel-to-air ratio, among others. Since the combustion characteristics are different in the different types of burners, the characterisation of primary particles may offer the possibility to distinguish soot from different sources. In this paper, we present the signature of the primary particles and the aggregates of soot emitted by cars using diesel or biodiesel, by domestic heating, and by aircraft exhausts, which can be considered as the major sources as derived from measurements on transmission electron micrographs. The size distributions of all aggregates types with different aerodynamic diameter were log-normal and quasi-monodisperse. The size distribution of the primary particles for soot emitted by different sources showed minor differences. However, a comparison between the diameter of the primary particles and those obtained using a standard method for carbon black revealed discrepancies. The median diameter of the primary particles was combined with the median number of primary particles in an aggregate to calculate the relative particle surface area available for adsorption. In a similar way, the relative specific surface area was determined. The surface area was measured using the Brunauer-Emmett-Teller (B.E.T.) nitrogen adsorption method and the relative surface area available for adsorption was calculated.  相似文献   

A simplified method for simulation of strong ground motion using finite rupture model of the earthquake source     

A.?JoshiEmail author  S.?Midorikawa 《Journal of Seismology》2004,8(4):467-484

We present a simplified method to simulate strong ground motion for a realistic representation of a finite earthquake source burried in a layered earth. This method is based on the stochastic simulation method of Boore (Boore, D. M., 1983, Bull. Seism. Soc. Am. 73, 1865–1894) and the Empirical Greens Function (EFG) method of Irikura (Irikura, K., 1986, Proceedings of the 7th Japan Earthquake symposium, pp. 151–156). The rupture responsible for an earthquake is represented by several subfaults. The geometry of subfaults and their number is decided by the similarity relationships. For simulation of ground motion using the stochastic simulation technique we used the shapping window based on the kinetic source model of the rupture plane. The shaping window deepens on the geometry of the earthquake source and the propagation characteristics of the energy released by various subfaults. The division of large fault into small subfaults and the method for accounting their contribution at the surface is identical to the EGF. The shapping window has been modified to take into account the effect of the transmission of energy released form the finite fault at various boundaries of the layered earth model above the source. In the present method we have applied the correction factor to adjust slip time function of small and large earthquakes. The correction factor is used to simulate strong motion records having basic spectral shape of ² source model in broad frequency range. To test this method we have used the strong motion data of the Geiyo earthquake of 24th March 2001, Japan recorded by KiK network. The source of this earthquake is modelled by a simple rectangular rupture of size 24 × 15 km, burried at a depth of 31 km in a multilayered earth model. This rupture plane is divided into 16 rectangular subfaults of size 6.0 × 3.75 km each. Strong motion records at eight selected near-field stations were simulated and compared with the observed records in terms of the acceleration and velocity records and their response spectrum. The comparison confirms the suitability of proposed rupture model responsible for this earthquake and the efficacy of the approach in predicting the strong motion scenario of earthquakes in the subduction zone. Using the same rupture model of the Geiyo earthquake, we compared the simulated records from our and the EGF techniques at one near-field station. The comparison shows that this technique gives records which matches in a wide frequency range and that too from simple and easily accessible parameters of burried rupture.  相似文献   

线要素多尺度表达的一种新方法     

梁鹏  荣伟  李云锦 《测绘科学》2012,(4):129-131,134

本文依据多比例尺条件下矢量数据的绘制原理,提出了多尺度线化简与线选取方法。多尺度线化简算法依比例尺将空间坐标转换为像素坐标,根据像素坐标删除曲线中重合点与共线点,综合后的曲线与原始曲线在各比例尺下绘制结果相同;多尺度线选取算法利用仿射变换结果快速计算线要素之间的连通关系,然后渐进删除长度小于阈值的悬线与孤立弧段,保持了线要素的连通性。对不同类型数据的实验验证了本文算法的有效性和可行性。  相似文献   

地市级城镇天气预报制作及传输系统设计与实现     

刘春风  周立伟  余建华  张玉霞 《气象科技》2012,40(6):928-932

在城镇精细化预报制作和传输特点及需求分析的基础上,阐述了地市级城镇天气预报制作与传输系统的设计思路、功能实现和系统应用.系统选取PowerBuilder 7.0开发环境,PowerScript可视化编程语言,在Windows 2000操作系统上研制而成.由人机交互、预报自动传输和预报查询3个子系统构成,可制作城镇精细化、短时、评分、城区、城区上下班等多项预报,可随时查询利用该系统制作和传输到本地服务器上的各项预报,可用人工与自动两种方式向省局传输所需的预报.该系统为省级以下气象台的预报员提供了一个可靠、高效的预报制作、传输平台,为预报服务人员提供了一个方便、快捷的预报查询平台.  相似文献   

高空报文传输常见问题及处理方法     

韦肖林  韦丽英  文芳一  毛照军  赵琴 《气象研究与应用》2012,33(2):74-76

对全国三年来高空传输报文情况进行分析,指出报文传输过程中常见出错环节及问题,提出处理方法及应对措施,为高空气象业务观测员提供实用参考经验,确保报文传输的准确性和时效性,达到提高高空气象业务质量的目的。  相似文献   

移动地图的信息传输模型研究     

马超  刘文兵 《东北测绘》2012,(10):153-155

分析了移动地图的特点,通过对现有地图信息传输模型的改进,得到了一种基于移动通信条件下的地图信息传输模型。该模型强调了实时信息在移动地图信息传输中的重要作用,分析了移动地图的信息传输过程,为移动地图的设计提供了理论支持。  相似文献   

重庆10 kV高压输电线路雷击火灾事故分析   总被引：3，自引：2，他引：1  

李家启  申双和  陈宏  廖瑞金  任艳  林涛 《气象科技》2010,38(6):821-824

针对2007年7月12日重庆华浩冶炼有限公司粉末厂火灾事故,用力学性能分析和剩余磁场测试相结合的方法对该厂火灾发生处的10 kV高压输电线路进行鉴定,并结合雷电天气分析,得出该火灾事故是由雷击10 kV高压输电线路造成。该方法为在没有安装录波器和闪电计数器的情况下,判断输电线路故障是否由于雷击引起提供参考。  相似文献