合肥南环铁路某钢桁梁大桥测量监测控制

详细介绍新建合肥铁路枢纽工程南环线某钢桁梁大桥测量监控控制网的布设及施测。利用GPS对原有控制点进行复核、加密,再用全站仪进行校核,保证测量监控质量。     

基于Contourlet变换的遥感影像数字水印方案

针对现有变换域遥感影像数字水印算法存在的问题,提出一种基于Contourlet变换的遥感影像数字水印方案。算法首先对宿主遥感影像进行图像归一化;然后,对水印图像进行Arnold置乱预处理,并将置乱后的水印图像利用行扫描形成一维向量,得到二值水印序列作为数字水印信息;最后对宿主遥感影像进行Contourlet变换,并通过奇偶量化将水印嵌入所选Contourlet变换系数中。实验证明该算法对JEPG压缩、滤波和噪声以及旋转、缩放、平移等几何攻击均具有较好的鲁棒性。     

基于主色提取和主色集扩充的图像检索算法

提出一种基于主色提取和主色集扩充的图像检索算法。算法首先对图像进行主色特征提取,采用提出的改进主色集扩充方法分别对两图像进行主色集扩展,使其维数相同;然后,将经过主色提取得到的主色集从传统RGB颜色空间转换为具有良好视觉一致性HSV颜色空间;最后,采用Quadratic距离进行图像的相似性度量。实验证明算法易于实现、具有较好的时间复杂度及较高的查准率和查全率。     

双轴旋转光纤捷联惯导八位置标定方法

针对双轴旋转捷联惯导系统长期工作时光纤陀螺误差参数随时间变化问题,提出一种姿态未知条件下的八位置标定方法.该方法利用双轴旋转机构可提供惯性测量单元(LMU)相对载体固定角位置特性,结合光纤陀螺简化误差模型,设计出八位置标定路径并激励出光纤陀螺误差参数.新的标定方法既避免了陀螺误差参数的耦合影响,又可以解算出载体航向信息.转台实验结果表明,八位置标定方法可在载体姿态未知条件下完成对光纤陀螺误差参数的标定工作.     

遥感图像中机场目标的识别方法

机场识别作为模式识别领域的问题之一,在军事上有着重要的应用前景。它包括判断机场是否存在和机场定位两个方面。结合已有的方法,提出了一种新的机场识别的解决方案。该方案先使用阈值分割方法进行图像分割,然后利用像素标记法提取出最大连通区域,作为疑是机场区域(ROI);用Canny算子进行图像的边缘提取,提出了一种改进的Hough变换,能够从边缘图像中准确地提取出直线段,并最终实现机场跑道的定位。     

Shifting land-based coalitions in Shanghai's second hub

Hongqiao is one of China's largest ever urban development projects, and within Shanghai second only to Pudong. It is designed to kick-start growth in the western part of China's economic capital, just as Pudong did in the east. The project comprises a transport hub and a new central business district and involves the participation of an array of organizations, including government at various levels, specially created bodies, property developers and banks. The central argument of this paper is that these organizations formed what can best be conceived of as a government-led land-based urban growth coalition and that this coalition became the driving force behind the Hongqiao project. It further argues that, rather than being one monolithic coalition, this was a shifting constellation of corporate actors, forming informal subcoalitions with different but interlocking roles and functions. The paper concludes by arguing that land-based urban growth coalitions rely on participants benefitting from rising land and property values once land has been developed, but for this debt financing is required, and this comes with its own substantial problems. The concept of land-based urban growth coalition can be useful in helping to interpret urban change in China so long as the coalition is examined in some detail.     

Reality check: Planning education in the African urban century

Planning in Sub-Saharan Africa owes much to the colonial legacies that inform the shape and composition of African urban spaces and places. This applies to legislation, institutional systems and planning education. In 2008, the Association of African Planning Schools AAPSs embarked on a 3-year initiative on the revitalisation of planning education in Africa, funded by the Rockefeller Foundation. The aim of the project was to propose ways through which the training of urban planners can be more responsive to the special circumstances of African urbanisation. This paper reflects on this initiative.     

基于MATLAB的GPS网三维平差方法研究

研究了GPS控制网平差模型，探讨了采用MATLAB进行GPS网三维平差的可行性，并结合GPS控制网三维无约束平差实例的结果进行分析。实例证明，基于MATLAB进行GPS网平差具有精度高、编程简单、工作效率高、平差过程清晰等优点。为解决复杂的GPS网平差计算提供了新的便捷途径。     

A 3D indoor positioning system based on low-cost MEMS sensors

A positioning system in the absence of GPS is important in establishing indoor directional guidance and localization. Inertial Measuring Units (IMUs) can be used to detect the movement of a pedestrian. In this paper, we present a three-dimensional (3D) indoor positioning system using foot mounted low cost Micro-Electro-Mechanical System (MEMS) sensors to locate the position and attitude of a person in 3D view, and to plot the path travelled by the person. The sensors include accelerometers, gyroscopes, and a barometer. The pedestrians motion information is collected by accelerometers and gyroscopes to achieve Pedestrian Dead-Reckoning (PDR) which is used to estimate the pedestrian’s rough position. A zero velocity update (ZUPT) algorithm is developed to detect the standing still moment. A Kalman filter is combined with the ZUPT to eliminate non-linear errors in order to obtain accurate positioning information of a pedestrian. The information collected by the barometer is integrated with the accelerometer data to detect the altitude changes and to obtain accurate height information. The main contribution of this research is that the approach proposed fuses barometer and accelerometer in Kalman filter to obtain accurate height information, which has improved the accuracy at x axis and y axis. The proposed system has been tested in several simulated scenarios and real environments. The distance errors are around 1%, and the positioning errors are less than 1% of the total travelled distance. Results indicate that the proposed system performs better than other similar systems using the same low-cost IMUs.     

A method of automatic extraction of parameters of multi-LoD BIM models for typical components in wooden architectural-heritage structures

A building-information-modeling (BIM) model, which is established based on high-fidelity point-cloud data, can be well used to preserve architectural heritage. Two related critical issues for this conservation are multiple-level-of-detail (multi-LoD) parametric models that emphasize different protection requirements for typical components, and a method for automatically extracting the corresponding parameters from a high-fidelity point cloud. Taking typical Chinese wooden architectural-heritage structures as an example, multi-LoD principles for typical components without damage are proposed according to the different requirements. Then, a framework of multi-LoD parametric models was developed and implemented in BIM. Based on this, a method for automatically extracting the abovementioned parameters is developed and the critical parameters of this method are recommended. To validate the reliability and efficiency of this method, the parameters of multi-LoD models of typical components are extracted. The results indicate that the relative and absolute errors of values of such parameters are mostly less than 2% and 0.5 mm, respectively. Moreover, this method is capable of extracting parameters from millions of point-cloud data within 7 min, thus validating the high efficiency and reliability of the proposed method.