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491.
尝试应用MAPGIS手段对新疆40年来的气温、积温、降水、蒸发等要素进行了一系列的计算、分析和制图。生成图像、数据可与其它应用系统进行信息交换、输出编辑图文并茂的应用产品。开拓性、探索性地开展气象服务信息化工作。 相似文献
492.
薛洁 《沙漠与绿洲气象(新疆气象)》2002,25(5):32-34
介绍了新疆铁路大风监测系统的设计思路、系统结构、系统的特点及功能等研制情况。该系统在铁路安全运输中发挥了重要的作用。 相似文献
493.
494.
通过对海温资料和500hPa位势高度、垂直速度、850 hPa的水平风分量资料的分析,探讨ENSO的各不同阶段西太平洋副高和东亚季风的变化特征.结果表明:赤道东太平洋海温与西太平洋副高有密切的关系.Nino 1+2区海温有明显的10年际变化,与西太平洋副高的1O年际变化非常吻合;前期Nino 1+2区为冷、暖水期时西太平洋副高的强度和位置有明显差异,前期为暖水期时夏季西太平洋副高较强,范围向西和向南伸展,冷水期反之,西太平洋副高较弱,位置偏东偏北.西太平洋副高的变化进一步影响东亚季风和我国的降水.这种影响在Nino 1+2区海温变化后4~6个月最明显.因此,前期Nino 1+2区海温的变化可以为东亚季风和我国降水的长期预报提供依据. 相似文献
495.
应用NOAA-AVHRR气象卫星数据,通过近似的大气校正模型及双向反射模型,结合地理信息系统,建立了动态的反照率反演模型,并反演计算了我国长江三角洲地区1995年3~12月的地表反照率.通过对诸多影响反照率变化因子的分析显示,遥感反演结果与地表覆盖特征及气候特征基本相符. 相似文献
496.
区域间技术和创新传播的理论分析与政策思考 总被引:4,自引:0,他引:4
新古典区域经济学有关区域间技术与创新传播的理论存在明显的缺陷,从理论上分析,等级传播与波浪式传播是区际技术与创新传播的两种主要方式,在这两种不同传播与扩散方式并不是朴素排斥的,在不同的发展阶段,区域间技术与创新传播的样式有所不同,且其影响也不同,在理论分析的基础上,文章针对西部大开发战略提出了一些政策建议。 相似文献
497.
Zoltan A. Der Douglas R. Baumgardt Robert H. Shumway 《Geophysical Journal International》1993,115(3):1012-1024
The particle motion of regional arrivals is frequently treated in automatic phase-recognition schemes as that appropriate to simple P or S waves incident on an elastic, laterally homogeneous half-space. This model implies that the motion in ' P -type' phases can be described in terms of a single, generalized signal process and ' S -type' phases in terms of two independent processes ( SV and SH ) and thus, all regional arrivals could be fully characterized by three components of motion. In this paper, we present anlyses of the particle-motion patterns of various regional arrivals recorded at the ARCESS array from closely spaced events in the Kola Peninsula. We have found that only Pn -particle motion, described in terms of two independent signal processes, can be reliably characterized by three-component recordings. On the other hand, the various regional arrivals following Pn , such as Pg and Sn and Lg , can only be poorly characterized on the basis of three-component recordings alone. The reason is that these arrivals must be described in terms of more than two independent generalized signal processes, at least three for Pg and Sn , and possibly up to five for Lg . Recognition of these phases will thus require the use of more sensors than signal processes in the observing sensor configuration, such as three-component sensors combined with a small tripartite array. We have investigated the feasibility of adaptive, automatic recognition of regional arrivials by a wavefield extrapolation scheme utilizing such a mini-array. The process, which appear to be promising, adaptively learns the particle-motion patterns of individual arrivals, including complex site-response functions, from examples of closely located regional events. 相似文献
498.
499.
Geometrical structure of shear wave surfaces near singularity directions in anisotropic media 总被引:1,自引:0,他引:1
There are three types of surfaces which are used for studying wave propagation in anisotropic media: normal surfaces, slowness surfaces and wave surfaces. Normal surfaces and slowness surfaces have been researched in detail. Wave surfaces are the most complicated and comparatively poorly known compared with the other two. Areas of complicated geometrical structure of the wave surfaces are located in the vicinity of conical acoustic axes. There is an elliptical hole on the quick shear wave surface and complicated folds and cusps on the slow shear wave surface. Decomposition of the slow shear wave surface into smooth sheets is used for the study of its geometrical structure. Complexity of shear wave surfaces can be expressed by the number of waves corresponding to a fixed ray. An original approach to the calculation of wave normals depending on ray direction is presented. 相似文献
500.
Edward W. Bolton 《Geophysical Journal International》1993,115(3):654-666
We present a simple notation for performing differential vector operations in orthogonal curvilinear coordinates, and for easily obtaining partial differential expressions in terms of the physical components. We express n th-order tensors as the summed products of the physical components and n th-order polyads of unit vectors (an extension of Gibbs dyadic notation convenient for a summation convention). By defining a gradient operator with partial derivatives balanced by the inverse scale factors, differential vector (or tensor) operations in orthogonal coordinates do not require the covariant/contravariant notation. Our primary focus is on spherical-polar coordinates, but we also derive formulae which may be applied to arbitrary orthogonal coordinate systems. The simpler case of cylindrical-polar coordinates is briefly discussed. We also offer a compact form for the gradient and divergence of general second-order tensors in orthogonal curvilinear coordinates, which are generally unavailable in standard handbooks. We show how our notation relates to that of tensor analysis/differential geometry. As the analysis is not restricted to Euclidean geometry, our notation may be extended to Riemannian surfaces, such as spherical surfaces, so long as an orthogonal coordinate system is utilized. We discuss the Navier-Stokes equation for the case of spatially variable viscosity coefficients. 相似文献