黑河流域中游无人机遥感影像数据处理

无人机低空遥感技术是航空遥感领域一个新的发展方向,具有低成本、快捷、灵活机动,以及数据高时效、高分辨率等特点。本文以无人机低空遥感在黑河流域中游张掖的应用为例,介绍了无人机低空遥感系统的基本构成,论述了影像数据的获取、影像的匀色、特征点的提取与匹配、几何纠正与镶嵌、DTM和DOM的生成等处理流程与分析方法。实验结果表明,无人机低空遥感系统能够满足局部区域内的高分辨率、大比例尺基础数据采集的实际需求,在三维重建、土地调查、环境监测等领域具有良好的应用前景。     

Positional accuracy improvement: a comparative study in Shanghai,China

With the rapid development of geospatial data capture technologies such as the Global Positioning System, more and higher accuracy data are now readily available to upgrade existing spatial datasets having lower accuracy using positional accuracy improvement (PAI) methods. Such methods may not achieve survey-accurate spatial datasets but can contribute to significant improvements in positional accuracy in a cost-effective manner. This article addresses a comparative study on PAI methods with applications to improve the spatial accuracy of the digital cadastral for Shanghai. Four critical issues are investigated: (1) the choice of improvement model in PAI adjustment; five PAI models are presented, namely the translation, scale and translation, similarity, affine, and second-order polynomial models; (2) the choice of estimation method in PAI adjustment; three estimation methods in PAI adjustment are proposed, namely the classical least squares (LS) adjustment, which assumes that only the observation vector contains error, the general least squares (GLS) adjustment, which regards both the ground and map coordinates of control points as observations with errors, and the total least squares (TLS) adjustment, which takes the errors in both the observation vector and the design matrix into account; (3) the impact of the configuration of ground control points (GCPs) on the result of PAI adjustment; 12 scenarios of GCP configurations are tested, including different numbers and distributions of GCPs; and (4) the deformation of geometric shape by the above-mentioned transformation models is presented in terms of area and perimeter.

The empirical experiment results for six test blocks in Shanghai demonstrated the following. (1) The translation model hardly improves the positional accuracy because it accounts only for the shift error within digital datasets. The other four models (i.e., the scale and translation, similarity, affine, and second-order polynomial models) significantly improve the positional accuracy, which is assessed at checkpoints (CKPs) by calculating the difference between the updated coordinates transformed from the map coordinates and the surveyed coordinates. On the basis of the refined Akaike information criterion, the two best optimal transformation models for PAI are determined as the scale and translation and affine transformation models. (2) The weighted sum of square errors obtained using the GLS and TLS methods are much less than those obtained using the classical least squares method. The result indicates that both the GLS and TLS estimation methods can achieve greater reliability and accuracy in PAI adjustment. (3) The configuration of GCPs has a considerable effect on the result of PAI adjustment. Thus, an optimal configuration scheme of GCPs is determined to obtain the highest positional accuracy in the study area. (4) Compared with the deformations of geometric shapes caused by the transformation models, the scale and translation model is found to be the best model for the study area.     

新型超高层节能建筑抗风研究

在大气边界层风洞进行了"珠江城"商务写字楼大比例尺(1:150)模型风洞试验,通过对风洞试验数据分析,获得了基础等效静风荷载及结构顶部风致加速度响应。并将其结果与其它较小比例尺的两个风洞试验结果相对比,分析了模型几何缩尺比、周边建筑及平均风剖面对试验结果的影响。获得的结果可以为此结构设计提供风荷载,同时也为其他建筑的抗风设计和风洞实验提供技术参考。     

1991年来台商在大陆直接投资区位选择及驱动机制

采用1991-2011 年台商大陆投资资料,分析在较长时间尺度上、随台海局势不断变化,台商对大陆直接投资行为的转变,并从大陆整体层面及各经济区两个空间尺度进行驱动机制变化研究。结果表明：自1991 年起,台商在大陆地区投资规模（尤其是投资金额） 显著上升,累计金额呈“T”字型分布;TDI 在大陆分布存在一定的空间集聚及明显的“核心—外围—边缘”梯度结构,投资热点及次热点均向北推移,热点最终停留于长三角地区。台商在大陆直接投资的主要驱动因素由前期（1991-2000） 的地区电信发展水平、市场规模、劳动力成本、电力供应水平、高素质劳动力、政策环境、对外开放度,以及交通运输水平,转变为后期（2001-2011） 的前期台资累积量、对外开放水平、地区市场规模、高素质劳动力、劳动力成本、区域政策环境、电力供应水平,以及产业集聚水平。具体至各经济区,其不同要素的发展水平对TDI的吸引程度不同,文化距离因素的影响仍然存在。     

附加线性不等式约束的条件平差模型未知参数的解算

讨论附加线性不等式约束的条件平差模型的解算思路。根据K-T定理,对拉格朗日乘子λ进行约束,通过迭代算法求解满足K-T条件的拉格朗日乘子,进而求得未知参数的最佳估值,并用算例验证该方法的可行性。     

Allowance of lateral breakthrough error for super long tunnels from 20km to 50km

Up to now there is no specification about the allowance of lateral breakthrough error for super long tunnel from 20 km to 50 km. On the basis of the design of GPS networks located outside and inside tunnel traverse network, we propose a method for calculating the influence value caused by control surveying errors.Through a lot of simulative calculations and combination with piercing practice of super tunnels in Wan Jiazai Project, Shanxi province, we present an allowance table of lateral breakthrough error for super long tunnels from 20 km to 50 km.     

青海省东草河地区铀矿化特征及找矿前景

东草河地区地处祁连-龙首山碱交代型铀成矿带,铀矿（化）体主要产于构造破碎带中,断裂构造多期次活动和碱交代岩的二次破碎是铀矿化形成的必要条件;通过对岩石样品的岩相学分析、电子探针分析,表明东草河地区的铀矿化为碱交代型;东草河地区具备地层、构造、岩浆岩、热液活动及围岩蚀变等有利成矿条件,围绕已发现的3条矿化蚀变带存在较好的找矿前景。