海杂波微弱目标分形检测

The target on the sea surface is complex and difficult to detect due to the interference of backscattered returns from the sea surface illuminated by the radar pulse. Detrended fluctuation analysis （DFA） has been used successfully to extract the time-domain Hurst exponent of sea-clutter series. Since the frequency of the sea clutter mainly concentrates around Doppler center so that we consider to extract frequency-do- main fractal characterization and then detect a weak target within sea clutter by using the difference of frequency-domain fractal characterization. The generalized detrended fluctuation analysis （GDFA） is more flexible than traditional DFA owing to its smoothing action for the clutters. In this paper, we apply the GDFA to evaluate the generalized Hurst exponent of sea-clutter series in the frequency domain. The difference of generalized Hurst exponents between different sea-clutter range bins would be used to determine whether the target exists. Moreover, some simulations with the real IPIX radar data have also been demonstrated in order to suooort this conclusion.     

基于移动GIS和LBS技术的地名地址快速采集方法研究与应用

介绍移动GIS的特点和LBS定位技术,针对目前地名地址采集过程中存在的数据采集不准确、不规范和周期长等一系列问题,设计了从外业拍照、数据采集、内业录入到数据更新的地名地址数据采集流程,并开发了地名地址数据采集系统,其次,介绍地名地址采集系统的实现和功能配置,并结合实例分析系统的应用情况.系统既简化了地名地址的采集流程,同时又提高了数据采集的效率.     

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线状空间数据传输的几何相似性度量算法与实验分析

 同一地物在不同比例尺或者不同来源的地图上通常存在着相似性,对于图形几何形似性度量方法的研究有利于地图编制、查询、匹配、更新。线状地物要素在地图中占有很大的比例,因此,本文以线状空间目标为例,在前人的基础上给出了线状空间数据的几何图形相似性度量模型:(1)以差异距离作为相似性特征的位置相似度;(2)以分形维数作为相似性特征的形状相似度;(3)以长度或者周长作为相似性特征的大小相似度。相对于(3)大小相似度而言,(1)位置相似度、(2)形状相似度综合考虑了几何图形整体统计的方法和局部几何特征结构。完成多尺度传输的线状空间数据几何相似性度量实验,并对数据传输量与几何相似性度量方法进行比较,实验结果表明:基于广义Hausdorff距离模型的中位数Hausdorff距离的位置相似性对于空间数据渐进性传输具有稳定性和可行性。最后,总结了本文的研究成果,并展望了该方向进一步研究的若干问题。     

异心球形电容器电容的精确解

提出了导体系统电容问题求解的一种新方法，借助双球面坐标系和平行板电容公式，求出了异心球形电容器电容的解析式。此外，对另外几种类型异体系统的电容也作了讨论。     

区域CORS网坐标时间序列周期特征分析

通过精密单点定位的方法获取了区域CORS网各基准站的坐标时间序列,并利用最大似然估计法和频谱分析法对其32个基准站坐标时间序列的周期特征进行了分析,获取了各基准站年周期、半年周期的振幅和相位值,以及各基准站的周期功率谱图。结果表明:GNSS基准站坐标时间序列不仅存在线性变化,还存在周期性变化,其中以U方向表征最为明显,与双差定位获得的坐标时间序列周期特性分析结果一致,说明以精密单点定位获取的GNSS基准站坐标时间序列是可靠的,可以用来分析基准站的变化特征。     

中小地形对局地天气气候的影响

本文采用地形活动坐标系,研究在二维运动条件下地形对局地天气气候的影响。指出:地形对气流的影响不仅与地形高度z有关,而且与地形的坡度α,下垫面的热力分布,近地层大气稳定度г,垂直交换系数k以及基流v等诸因素密切相关。其中下垫面温差,地形坡度和基流尤为重要。     

Long-term growth of the oil industry in the United States

A number of growth models have been developed and used in an attempt to project the historical pattern of oil activities to some estimate of their upper limit. Techniques are outlined for the estimation of parameters of the logistic and Gompertz curves. Factor analysis indicated a close relationship between production and demand, whereas annual discoveries and discoveries classified by year of discovery tended to comprise unique factors which were indifferent to changes in time. The growth models projected relatively high values for ultimate demand and production in comparison to the figures for ultimate reserves. Inasmuch as these trends seemed to be occurring independently, some reconciliation of the results was necessary. Using the highest projections of estimates for reserves suggests that over 420 billion barrels of oil in place will eventually be discovered in the United States, with perhaps 200 billion barrels of this eventually to be proved in the form of reserves. Projections for production were higher, corresponding to a trend indicating high levels in demand for crude oil. The only credible long-term estimate of demand was given by a bounded exponential growth model, in which ultimate cumulative demand for crude oil would reach about 416 billion barrels. These figures imply that over 150 billion barrels of oil would be imported into the United States from 1970 to 2070. Provided the time pattern for one of the variables has been determined, then estimates of the other variables probably would be facilitated because of the high interrelationship between variables. Models are suggested in which accurate pivotal forecasting in the short term might be possible—assuming the particular future trend in some of the independent variables has been predetermined.Research Council of Alberta Contribution No. 596.     

非保守弹性动力系统两类变量的广义拟变分原理及其应用

按照广义力和广义位移之间的对应关系,将弹性动力学的各基本方程分别乘上相应的虚量,然后在相应的体积域和面积域上积分,将积分式代数相加,再将代数和在时间域上积分,代入本构关系,并考虑到体积力和面积力均为伴生力,进而建立了非保守弹性动力系统的第1类两类变量的广义拟变分原理;再应用类似的方法,通过代入另一类本构关系,建立了非保守弹性动力系统的第2类两类变量广义拟变分原理.应用第1类两类变量广义拟余能原理给出同时求解1个典型的非保守弹性动力系统的固有频率、变形和内力的计算方法.最后,讨论了有关问题.     

道路平面测设计算的通用公式

基于各类道路线型曲率呈线性变化的共同特性,给出了线元上任意点坐标方位角的统一计算公式,进而提出了适用于所有道路线型平面测设计算的中桩坐标、边桩坐标的通用公式。在此基础上,讨论线路外一点对应中桩的计算以及直线与线路交点的计算,给出了相应的计算方案。