Spherical gauges for improving the accuracy of rainfall measurements

Rain‐gauge catch efficiencies are affected by wind. Wind makes raindrops fall at an angle of inclination and the effective diameter of the rain gauge orifice smaller than if raindrops fall into the gauge vertically. Two spherical and two semi‐spherical orifices were designed to modify standard gauges and others in use today. The two spherical orifices catch rain with an effective diameter always equal to the actual diameter regardless of wind speed and direction. The semi‐spherical orifices, used side‐by‐side with a standard gauge, correct 50% of catch deficiencies made by the standard gauge. Tests based on 115 storms show that the four new gauges caught more rainfall than the standard gauge, with an average catch increase ranging from 8% to 16%. Compared with the pit gauge, average deficiency in catch ranged from ?1% (spherical rain gauge orifice with cylinders) to 4%, whereas the deficiency for the standard gauge was ?10%. Percentage deficiencies of the new gauges were positively affected by wind speed, raindrop inclination and rainfall intensity. Although the new gauges tended to underestimate the standard gauge in small storms (<0·25 cm) and overestimated the pit gauge under strong winds, their deviations are small. Underestimates for small storms could be improved by using gauge materials that reduce surface temperature, evaporation and water retention. The gauges are simple in design, easy to operate and inexpensive. In order to maintain a historically consistent set of rainfall data, a dual‐gauge (standard gauge + spherical gauge) is recommended for existing rainfall stations. The new rain gauge orifices are suitable for large‐scale applications. Copyright © 2001 John Wiley & Sons, Ltd.     

中国内陆沿边省份对外开放竞争力研究

依据中共十八届四中全会提出的努力稳定对外贸易,提高对外开放水平的要求,结合中国内陆沿边9省份的实际情况,建立了由经济发展水平、对外贸易发展、对外旅游发展3项一级指标和12项二级指标组成的中国内陆沿边省份对外开放竞争力评价指标体系.采用主成分分析法对对外开放竞争力指标进行分析,得出内陆沿边九省份对外开放竞争力得分和排名,辽宁省的对外开放竞争力水平最高,其次是云南、黑龙江和广西,新疆、内蒙古、吉林、西藏、甘肃对外开放竞争力较弱.最后针对9省份提出提升对外开放竞争力的建议.     

青藏高原山地系统动力学模型研究

以地球系统科学为研究思路。研究了青藏高原山地系统各圈层相互作用的统一构造动力模型、力学模型和数值模拟等。关于青藏高原山地系统动力学特征。主要研究高原山地系统现今构造应力场演化特征和高原山地系统统一构造动力模型。认为均起源于喜马拉雅运动期印度一欧亚板块碰撞引发的统一的板块汇聚动力体系和各圈层与之相应的一系列运动学和动力学过程。关于青藏高原山地各圈层力学系统描述，主要把山地各圈层块体质点作为一个力学系统来描述。求解速度向量、位移向量、密度场、温度场、应力张量等物理量和状态空间。最后求解运动方程。关于青藏高原山地系统的非稳定性问题。将给定的载荷历史分成许多小的增量步。对每一个增量步求解一个非线性边值问题。使用失稳量准则判断山地系统的稳定性。关于青藏高原山地各圈层多体系统力学描述。青藏高原是由多圈层多块体不同物质结构组成的。皆可用若干塑性、流变体、流体和弹性组成的系统模型予以有效地描述。主要研究内容有：高原山地系统碰撞隆升的分类和现象、山地主动碰撞构造体特性和山地被动碰撞体(靶体)特性等力学模型。文中初步分析和推断了演变的历史与现状。探讨了青藏高原隆升的动力学过程。     

A global spectral element model for poisson equations and advective flow over a sphere

A global spherical Fourier–Legendre spectral element method is proposed to solve Poisson equations and advective flow over a sphere. In the meridional direction, Legendre polynomials are used and the region is divided into several elements. In order to avoid coordinate singularities at the north and south poles in the meridional direction, Legendre–Gauss–Radau points are chosen at the elements involving the two poles. Fourier polynomials are applied in the zonal direction for its periodicity,with only one element. Then, the partial differential equations are solved on the longitude–latitude meshes without coordinate transformation between spherical and Cartesian coordinates. For verification of the proposed method, a few Poisson equations and advective flows are tested. Firstly, the method is found to be valid for test cases with smooth solution. The results of the Poisson equations demonstrate that the present method exhibits high accuracy and exponential convergence. Highprecision solutions are also obtained with near negligible numerical diffusion during the time evolution for advective flow with smooth shape. Secondly, the results of advective flow with non-smooth shape and deformational flow are also shown to be reasonable and effective. As a result, the present method is proved to be capable of solving flow through different types of elements, and thereby a desirable method with reliability and high accuracy for solving partial differential equations over a sphere.     

Assessing the implications of the recent community opening policy on the street centrality in China: A GIS-based method and case study

Recently, the Chinese government raised an urban planning policy which suggests communities open their private roads for public transport and establish street networks with high spatial density in cities. In this context, the purpose of this study is to analyze the potential changes to street network accessibility using GIS techniques and to provide spatial information that may influence the decision making of urban managers. In addition to the existing street network data in the case study city, Shenzhen, intra-community roads are extracted from building footprints in GIS topographic database and used to construct a potential street network with respect to the community opening policy. An automatic GIS-based method is proposed here to analyze the location advantage information in the simulated urban environment, by combining Delaunay triangulation model and graph theory concepts. Specifically, we establish a two-step framework based on the spatial relationships between roads and buildings. Firstly, intra-community roads between neighboring building footprints are generated using a Delaunay triangulation skeleton model, and with the existing inter-community roads they form the simulated network. Secondly, street centrality indices of the current and simulated networks are compared in terms of closeness, betweenness and straightness. Results indicate that after applying the policy the global accessibility in the city would be increased at some places and decreased at others, and places' directness among others would be generally improved. In addition, the skeleton of central routes for through traffic would not change much. The presented method can also be applied to other cities.     

论中国主要沿边省区地域开发战略的调整*——以新疆、云南、黑龙江三省区为例

从区域开发的理论模式及其评价入手,结合沿边省区经济发展所处的阶段以及国家沿边开放政策的实施,以新疆、云南、黑龙江三省区为例,提出了中近期中国主要沿边省区的外向性地域开发战略。     

内核地球自转动力学理论的研究进展(Ⅰ)

地球固体内核（SIC）和地球其余部分之间的引力和压力的耦合作用引起了一个力矩，从而对地球的章动运动产生影响.由于SIC的转动惯量和整体地球转动惯量相比是非常小的，因此可以认为SIC的动力学效应只是导致一个新的章动本征模，其频率与自由核章动（FCN）相差不太远，且对地球章动产生了一个微弱的共振影响.本文在文献〔1〕理论的基础上，对内核地球自转动力学理论进行了更加深入和详细的研究，顾及到高阶引潮力位的影响，介绍了研究内核地球自转的基本假设和定义，引潮力位的复数球函数表示，复数矢量球函数的基本理论等.     

球面四元三角网的三拓扑数计算

讨论了任意球面三角格网p的三拓扑数计算.任意球面三角格网p的三拓扑数是指和该球面三角格网互为三邻近的目标球面三角格网的个数,它是讨论球面栅格区域局部拓扑不变量的重要参数,也是描述和推断球面栅格拓扑关系首先要解决的问题.