基于BP神经网络的地图数字化误差纠正

由于在数字化采集过程中不可避免地会引入系统误差和异常误差,因此消除和削弱这些误差的影响是提高空间数据质量的关键。然而由于图纸变形不均匀,扫描误差又极其复杂,用常规的多项式拟合技术只能消除部分有规律的系统误差,很难完全消除它们对地图数字化坐标的影响。BP神经网络是一个高度非线性映射系统,能以任意精度逼近。结合地图数字化坐标改正的特点,本文给出了基于BP神经网络地图数字化坐标误差纠正的方法,并通过实例验证了该方法的有效性。     

基于非等间距模型的建筑物沉降预测方法研究

该文基于实测资料进行建筑物沉降预测。在灰色模型和泊松曲线模型理论的基础上,引入对非等间距数列进行变换处理的方法,从而建立了非等间距预测模型。结合建筑物沉降监测资料进行分析比较,结果表明,两种预测方法均能较好地反映建筑物的沉降趋势。     

基于小波变换与滤波的DEM简化方法

针对现有3维地形模型简化方法中的不足,提出了一种基于小波变换与滤波的规则格网简化方法。同时还在大量实验的基础上,给出了一般情况下需要的变换层数,分析了滤波门限与简化效果之间的关系。这里的研究不仅为3维地形的多分辨率合理建模与精度评估提供了理论和方法,而且也为今后开展类似研究及进行建模质量控制提供了科学的依据。     

变形信号与噪声的分离方法及其应用

在对变形体进行监测的时候会得到一系列不同时间的观测结果,比如对滑坡的位移监测,得到一系列的坐标,通过与首期观测数据的比较可获得变形量,然而测量中不可避免的含有误差,如何将变形信息和观测噪声分离是一个需要解决的问题。本文在变形是一个连续过程的假设下,以给定的验前方差为约束条件,通过三次连续逼近样条函数建立变形曲线,达到变形信号与噪声分离的目的,文中通过对某滑坡多年监测数据的分析验证了该方法的可行性。     

地图误差对地图匹配质量的影响

高精度的数字地图是正确匹配车辆位置的基础。详细分析了地图数据的地理误差和拓扑误差的误差形式,路网数据模型的常见误差因素和改进策略,最后介绍了不同地图匹配算法对地图质量的敏感性和可行性。根据可能出现的误差对现有数字地图和匹配算法加以改进,弥补了原有数字地图带来的不精确缺陷。跑车实验证明,考虑了数字地图误差影响的匹配算法可以明显提高定位精度,减小车辆定位误差。     

GPS单点测速的误差分析及精度评价 (英文)

Error sources which decrease the accuracy of GPS in absolute velocity determination have been changed since SA was turned off. Firstly, quantities of all kinds of error sources that influence velocity determination are analyzed. The potential accuracy of GPS absolute velocity determination is derived from both theory and field GPS data simulation. After that, two tests were carried out to evaluate the performance of GPS absolute velocity determination in the case of a static and an airborne GPS receiver and INS （Inertial Navigation System） instrument in kinematic mode. In static mode, the receiver velocity has been estimated to be several mm/s with the carrier-phase derived Doppler measurements, and several cm/s with the receiver generated Doppler measurements. In kinematic mode, GPS absolute velocity estimates are compared with the synchronized measurements from the high accuracy INS. The root mean square statistics of the velocity discrepancies between GPS and INS come up to dm/s. Moreover, it has a strong correlation with the acceleration or jerk of the aircraft.     

水平井含水率上升影响因素

利用塔里木油田塔中4油田(TZ4)底水油藏相关的地质、流体数据建立数值模型。在所建模型的基础上,应用数值模拟计算的累积产油、产水和产液量回归俞启泰水驱特征曲线,以反映水平井见水特征的参数b。以参数b为研究对象,采用正交试验的方法研究不同因素对b值的影响,筛选影响水平井见水特征的主要因素,认为原油粘度、油层厚度、非均质性及水平井水平段在油藏中的位置是影响水平井含水上升趋势的主要指标。最后建立主要因素与b值的关系式,结合俞启泰曲线b值图版,提出预测水平井见水规律的公式——图版法(F-b法)。应用F-b法对塔里木水平井含水率进行预测,并与其他相关方法及实际生产数据对比,认为F-b法可作为预测塔里木油田水平井含水率、估算可采储量的一种有效方法。     

火山沉积岩及其矿床研究中伽马测井曲线解释的误区

根据酸性凝灰岩和酸性火山事件粘土岩的自然伽马测井曲线,对当前流传的"沉积岩层的放射性强度(或放射性核素的含量)随泥质含量的增加而增高"的概念和用自然伽马值及经验公式求泥质含量提出质凝。酸性凝灰岩的自然伽马曲线有高异常响应,若解释为泥岩显然是误解,故将沉积岩伽马曲线高异常一律解释为泥岩是片面的。各类火山事件粘土岩的伽马值相差悬殊,但其泥质含量几乎相等,用它们的伽马值计算泥质含量误差甚大。最后对铝土矿层的伽马曲线稍加解释,指出核测井应用的远景。     

Modelling Positional Uncertainty of Line Features by Accounting for Stochastic Deviations from Straight Line Segments

The assessment of positional uncertainty in line and area features is often based on uncertainty in the coordinates of their elementary vertices which are assumed to be connected by straight lines. Such an approach disregards uncertainty caused by sampling and approximation of a curvilinear feature by a sequence of straight line segments. In this article, a method is proposed that also allows for the latter type of uncertainty by modelling random rectangular deviations from the conventional straight line segments. Using the model on a dense network of sub‐vertices, the contribution of uncertainty due to approximation is emphasised; the sampling effect can be assessed by applying it on a small set of randomly inserted sub‐vertices. A case study demonstrates a feasible way of parameterisation based on assumptions of joint normal distributions for positional errors of the vertices and the rectangular deviations and a uniform distribution of missed sub‐vertices along line segments. Depending on the magnitudes of the different sources of uncertainty, not accounting for potential deviations from straight line segments may drastically underestimate the positional uncertainty of line features.     

GPS控制网环检验程序的设计

在GPS控制测量中,环检验是个不可或缺的步骤,其目的在于及时发现粗差,控制整网的精度。本文通过设计一个环检验程序,从算法角度讨论了手工检验和自动检验的具体实现,并详细介绍了针对复杂网形控制网构环算法的优化,保证了程序的可靠性和稳健性。