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141.
Peng Wang Lei Liu Xichuan Liu Shuai Hu Shijun Zhao Wenming Ji Taichang Gao 《地球科学进展》1986,35(7):704-714
The accurate observation of the microphysical structure of cloud and precipitation plays an important role in understanding the formation of clouds and precipitation. In-situ measurement using measuring instruments carried by meteorological balloons is an effective way to obtain the microphysical properties of cloud and precipitation particles, which is a supplementary means for aircraft to observe cloud and precipitation particles. This observation method plays a more and more important role in in-situ measurement. According to the difference of the working principle of the existing balloon-borne cloud and precipitation particles probes, the detectors can be divided into particle impact-sampling sensors, particle imaging sensors, light-scattering sensors, light intensity attenuation sensors and charge measurement sensors. The working principles, key technologies and main advantages and disadvantages of typical instruments were summarized, and their applications to detailed cloud structure acquisition, cloud remote sensing method establishment, cloud and precipitation physical process research and parameterization, and scientific observation of thunderstorm clouds were briefly introduced. Finally, the development trend of balloon-borne cloud precipitation particle detectors was prospected, which will provide reference for related technical research and equipment development. 相似文献
142.
Stefan Keller 《Surveys in Geophysics》1995,16(5-6):661-670
Laboratory simulation of powder snow avalanches serves for the validation of numerical models and as a tool in its own right for consulting and research purposes. Two-phase gravity currents are simulated in water with quartz powder or glass spheres as the particle phase. Particle-phase velocity profiles and particle-phase volume fraction profiles are measured with an ultrasonic device. The experimental setup and the current state of the measurement technique are described and preliminary results are presented. 相似文献
143.
1987年1月8日甘肃迭部5.9级地震与地形变特征 总被引:1,自引:0,他引:1
根据1987年1月8日甘肃迭部5.9级地震前,该区域的地壳形变中长期背景和定点台站连续观测资料的震反应异常,分析研究了这此异常的变化特征。 相似文献
144.
145.
拱形波纹钢屋盖动力特性测试及分析 总被引:2,自引:0,他引:2
拱形波纹钢屋盖是一种新颖的金属拱形薄壳结构,在我国已经得到了广泛的应用。由于结构的复杂性,目前有关的理论研究尚不够深入,动力研究还很少有人涉及。以18m和30m两种跨度的W666型拱形波纹钢屋盖为研究对象,测试了拱在竖向平面内振动时的频率、振型及阻尼。在所提简化计算模型的基础上,采用有限元方法计算了结构的动力特性,其结果与试验数据符合较好。测试和分析结果为该结构的动力反应研究提供了方便。 相似文献
146.
Vilmos Vasvri 《Atmospheric Research》2005,77(1-4):18
The Institute of Urban Water Management and Landscape Water Engineering of the Graz University of Technology (Austria) operates a hydrological research area in the City of Graz. In this urban research area precipitation and runoff data are collected by order of the municipality of Graz. At present precipitation data are measured by seven tipping bucket rain gauges. Comparative measurements have shown a deviation between the recorded and the actual precipitation intensity. This made the institute calibrate the rain gauges periodically. In the middle of the 1990s, the development of a field calibration kit was started. Based on the experiences with the first field calibration kit, a microprocessor controlled device was developed. With this calibration device, the tipping bucket rain gauges are calibrated at regular intervals. In this paper the calibration process and the current results for seven rain gauges are discussed. The calibration process is dynamic calibration and uses a peristaltic pump. Not all of the tipping buckets investigated underestimate the rain intensity in the whole measuring range. Several rain gauges have a positive relative deviation, not exceeding 22%, in the low intensity range up to 0.5 mm/min. Positive deviation can be explained by retention of water in the buckets between tips. The reason for the negative deviation is the loss of water during the tips. It leads to the underestimate of the actual intensity. The largest relative deviation in the range of underestimate exceeds 30%. In the range of extreme intensities, the larger buckets (5 cm3) show a lower relative deviation than the smaller (2 cm3) buckets. The gauge characteristic can change in favourable or unfavourable directions after several years. Therefore, the calibration of tipping buckets is recommended at least every 2 to 3 years. 相似文献
147.
青藏高原腹地现今构造活动强烈,为了解强烈构造活动下的应力背景,我们在五道梁、风火山、雁石坪和安多不同构造部位的四个测点采用压磁应力解除法进行了现场应力实测工作,测量深度12~20m.测量结果表明, 最大主应力方向总体为北东向,与地质、地震以及大地测量等方面的研究成果基本吻合;最大主应力量值为36~68MPa(安多测点除外),与其他地区测量结果相比,属于中等偏高;安多测点最大主应力方向为北西西向,最大主应力量值为81MPa,与其他测点有较大差别,反映了板块缝合带附近现今应力状态的复杂性. 相似文献
148.
三角形量测法在隧道变形监测中的应用研究 总被引:3,自引:0,他引:3
通过对隧道变形监测中三角形量测法原理、计算公式的分析,认为公式中的三角形三边长度并不是收敛计的读数,两者相差一个收敛计本身的附加长度,这是使监测数据产生误差的原因之一。同时探讨了忽略收敛计附加长度引起的误差对监测结果的影响,并结合工程实例介绍了在实测过程中应注意的问题及误差原因。 相似文献
149.
150.
Bolivia is a country with high levels of poverty and inequality among its peoples and regions. For the nation and its urban
and rural areas, trends in the social and spatial distribution of poverty (and extreme poverty) are identified from 1976 to
2003 using UBN data with minor support where appropriate from poverty lines. The main survey between 1992 and 2001 uses composite
and selected UBN to track detailed poverty change for the country’s nine departments, its ten largest cities and a selection
of other smaller urban and rural municipalities. Because of rising background increases in population in the various surveyed
administrative units, many instances of relative reductions in poverty are accompanied by rising absolute increases. Marked
spatial variations in poverty and development in the country over the last several decades are identified as the main driver
for the country’s quickening pace of rural–urban migration. As a result, the paper concludes by assessing two different but
closely related views. One investigation tests the notion that because more poor people have been living in Bolivia’s cities
than in its rural areas since the mid to late 1990s, rapid rural–urban migration has simply shifted the locus of poverty from
the countryside to the cities in a process called, the ‘urbanisation of poverty.’ A second, more challenging, investigation
assesses the view that the flow of poor rural people to the better serviced urban areas of Bolivia has actually acted to alleviate
national poverty levels. 相似文献