Small-world characteristics on transportation networks: a perspective from network autocorrelation

Studies on small-world networks have received intensive interdisciplinary attention during the past several years. It is well-known among researchers that a small-world network is often characterized by high connectivity and clustering, but so far there exist few effective approaches to evaluate small-world properties, especially for spatial networks. This paper proposes a method to examine the small-world properties of spatial networks from the perspective of network autocorrelation. Two network autocorrelation statistics, Moran’s I and Getis–Ord’s G, are used to monitor the structural properties of networks in a process of “rewiring” networks from a regular to a random network. We discovered that Moran’s I and Getis–Ord’s G tend to converge and have relatively low values when properties of small-world networks emerge. Three transportation networks at the national, metropolitan, and intra-city levels are analyzed using this approach. It is found that spatial networks at these three scales possess small-world properties when the correlation lag distances reach certain thresholds, implying that the manifestation of small-world phenomena result from the interplay between the network structure and the dynamics taking place on the network.      

苏通大桥钢箱梁制造几何控制三维高精度基准网测设

本文详细介绍了对苏通大桥主桥钢箱梁制造几何控制三维高精度基准网的测设，通过实际工程的实施对高精度三维基准网的方案设计和精度控制进行了有效的探索。     

改进的光谱角制图沿照度方向分类法及其应用——以ETM数据为例

选取多光谱遥感数据（ETM）对新疆北山西段中坡山笔架山一带进行了遥感蚀变信息提取方法研究。根据光谱角制图信息增强方法的优缺点,通过对光谱照度的研究,提出了结合光谱角分类方法进行沿光谱照度方向距离分类的信息提取方法。实验表明,该方法应用于ETM数据,增强了目标信息,同时剔除掉因照度所产生的大量非目标信息,为优化信息提供了一种有效的方法。在地形比较平坦的研究区取得了很好的应用效果。     

以TCSEC标准为基础对我国政府机关内部网络安全问题的探讨

通过对目前我国政府机关内网安全观念缺失的背景及安全缺陷的分析,提出目前内部网络安全缺陷的几种表现形式,并提出加强网络安全的几点对策和建议。     

煤矿地理信息系统数据模型的研究

地下煤矿开采所面对的空间目标具有灰色、动态变化的特征。本文在分析煤矿空间信息特点的基础上,提出了实用于煤矿的地理信息系统数据模型。这些数据模型包括全要素的结构化不规则三角网（ＴＩＮ）与ＧＩＳ一体化数据模型以及网状模型。     

钻井参数评价和优选的模糊综合评判方法

根据模糊综合评判理论,结合钻井资料的分析,建立了一套对钻井参数进行评价和优选的方法。整个过程简单易行,可对实际钻井中钻进参数的合理组配和优化提供有价值的信息。     

二滩水电站地震遥测台网持续时间震级的研制

利用二滩水电站地震遥测台网的速度量和位移量观测记录,收集了震级ＭＬ为０．４￣５．４的４６０次地震（Δ〈２１０ｋｍ）的振动持续时间３５００多条,制作了该台网的持续时间震级公式和便查表。在方法上,不同于通常的按一次或两次曲线拟合,而采取计算机自动分段按折线拟合的方法,以阻尼最小二乘法完成其计算;在资料上,先分台制作８个子台的持续时间震级公式,在此基础上选择仪器、台基及公式中参数相近的子台,制作了适用于     

中国数字地震台网数字化地震资料使用指南

由于数字地震记录仪具有记录频带宽,分辨率高,动态范围大以及易于用计算机处理等优点,所以数字地震台网产出的数字地震资料成为地震活动性,震源机制,地球内部研究,地震监测及预报等的最基本数据源。     

基于免疫进化算法的排放口最优规划

免疫进化算法是在现有进化算法的基础上发展起来的一种新的优化算法,其具有许多独特的性能.把该算法应用于排放口最优规划,结果表明:免疫进化算法不仅取得了良好的应用效果,而且成功地解决了此类问题中存在的非线性目标函数、约束条件过于复杂、"维数灾"等问题.     

Concentration–discharge relationships reflect chemostatic characteristics of US catchments

Concentration–discharge relationships have been widely used as clues to the hydrochemical processes that control runoff chemistry. Here we examine concentration–discharge relationships for solutes produced primarily by mineral weathering in 59 geochemically diverse US catchments. We show that these catchments exhibit nearly chemostatic behaviour; their stream concentrations of weathering products such as Ca, Mg, Na, and Si typically vary by factors of only 3 to 20 while discharge varies by several orders of magnitude. Similar patterns are observed at the inter‐annual time scale. This behaviour implies that solute concentrations in stream water are not determined by simple dilution of a fixed solute flux by a variable flux of water, and that rates of solute production and/or mobilization must be nearly proportional to water fluxes, both on storm and inter‐annual timescales. We compared these catchments' concentration–discharge relationships to the predictions of several simple hydrological and geochemical models. Most of these models can be forced to approximately fit the observed concentration–discharge relationships, but often only by assuming unrealistic or internally inconsistent parameter values. We propose a new model that also fits the data and may be more robust. We suggest possible tests of the new model for future studies. The relative stability of concentration under widely varying discharge may help make aquatic environments habitable. It also implies that fluxes of weathering solutes in streams, and thus fluxes of alkalinity to the oceans, are determined primarily by water fluxes. Thus, hydrology may be a major driver of the ocean‐alkalinity feedback regulating climate change. Copyright © 2009 John Wiley & Sons, Ltd.