利用FFT技术计算垂线偏差研究

首先导出了更加严密的二维平面FFT垂线偏差计算公式 ,在深入分析和比较二维平面和二维球面FFT算法特点和差异的基础上 ,给出了二维球面FFT计算公式的改进形式 ,并通过大量的数值计算 ,详细讨论了参考场选取、积分球冠半径确定、边缘效应、积分元离散化误差以及计算点奇异积分处理对垂线偏差计算结果的作用和影响。最后 ,利用全国 5′× 5′实测重力异常对我国海陆垂线偏差进行了试算 ,并将计算结果同实际观测值作了比较。     

消费型倾斜无人机技术在旧城区改造的应用

系统介绍倾斜无人机摄影测量系统及关键技术.首先,对整个旧城区进行规划,设计航线区域,对不同的建筑物采用不同的数据采集方法获取多视影像数据;然后,对多视影像数据处理构建实景三维模型的技术流程进行详细的论述,并建立旧城区的实景三维模型;最后,通过量测模型点的三维坐标与外业实测数据进行精度对比分析.结果表明,采用倾斜无人机摄影测量技术获取的多视影像数据构建实景三维模型精度满足1:500大比例尺测图应用需求.     

顾及海底地形非线性项的最小二乘配置反演方法

针对目前常用的反演海底地形方法主要考虑海底地形和卫星测高重力数据线性趋势项而忽略非线性项影响现状,提出了顾及海底地形非线性项的最小二乘配置反演方法.选择日本海某海域作为目标海区,利用卫星测高重力异常和重力异常垂直梯度数据作为输入源进行了方法试算并构建了相应的海深模型,然后以实际船测海深作为外部检核参考,评估了反演模型效能,同时分析了反演模型频谱特征.目标海区试验结果表明:相较于本文仅仅考虑海底地形和重力数据线性趋势项采用最小二乘方法建立的海深模型,基于最小二乘配置方法,利用相同重力异常和重力异常垂直梯度数据获得的目标海区反演海深模型检核精度最低分别提高了大约2.5倍和3.5倍,相对精度最高分别提升了9.76％ 和13.07％,极大地提升了海底地形建模质量;采用本文方法建立的海底地形模型在研究海域表现良好,反演模型与S&S V18.1、ETOPO1、GEBCO和BAT_VGG模型在研究海域相关系数均达到了0.95以上;在研究海区本文模型检核精度与S&S V18.1相当,远远优于ETOPO1等海深模型;本文模型可有效改善船测海深相关波段信息(本文反演波段范围为15～160 km),其中重力异常垂直梯度构建的海深模型相比重力异常为输入源建立的海深模型改善船测海深相关波段信息更为明显,验证了本文方法的可行性和有效性.     

一种改进的不适定问题奇异值分解法

综合截断奇异值法和奇异值修正法的特点,提出了一种改进的不适定问题奇异值分解法,先用截断参数将奇异值分为相对较大的奇异值和相对较小的奇异值;再用修正参数对相对较小的奇异值进行修正,以抑制其对观测噪声的放大作用。通过位场延拓中航空重力测量数据向下延拓的仿真实验,验证了改进的奇异值分解法要优于截断奇异值法、奇异值修正法和Tikhonov正则化法。     

New achievements of 1:50 000 regional geological survey of three sheets including Jingnan in Guizhou Province

In order to find out the distribution of strata, rock, paleontology and Carlin-type gold desposits in Southwestern Guizhou Province, the authors developed the 1:50 000 regional geological survey of Jingnan sheet, Bajie sheet and Pojiao sheet using the new methods of digital geological mapping, modern geological theory and test methods. The results show that the strata graphical units were clarified and divided, and that 18 informal mapping units were established according to rock associations as well as animal and plant fossils. Marine reptile fossils--Ichthyosaurid were first found in shelf facies of late Early Triassic at Northwestern Youjiang Basin. Marine reptile fossils--Nothosaurus were also found in platform-edge reefs facies of Middle Triassic. 11 new mineralization occurrences were discovered, including 9 gold mineralization occurrences, 1 molybdenum mineralization occurrence and 1 collophanite mineralization occurrence. This paper also delineated three metallogenic prospective areas and one target area. The research can provide useful information for geological and mineral investigations and researches in this area.     

On the evaluation of deflections of the vertical using FFT technique

There exist three types of convolution formulae for the efficient evaluation of gravity field convolution integrals, i.e., the planar 2D convolution, the spherical 2D convolution and the spherical 1D convolution. The largest drawback of both the planar and the spherical 2D FFT methods is that, due to the approximations in the kernel function, only inexact results can be achieved. Apparently, the reason is the meridian convergence at higher latitudes. As the meridians converge, the ??,?λ blocks do not form a rectangular grid, as is assumed in 2D FFT methods. It should be pointed out that the meridian convergence not only leads to an approximation error in the kernel function, but also causes an approximation error during the implementation of 2D FFT in computer. In order to meet the increasing need for precise determination of the vertica deflections, this paper derives a more precise planar 2D FFT formula for the computation of the vertical deflections. After having made a detailed comparison between the planar and the spherical 2D FFT formulae, we find out the main source of errors causing the loss in accuracy by applying the conventional spherical 2D FFT method. And then, a modified spherical 2D FFT formula for the computation of the vertical deflections is developed in this paper. A series of numerical tests have been carried out to illustrate the improvement made upon the old spherical 2D FFT. The second part of this paper is to discuss the influences of the spherical harmonic reference field, the limited capsize, and the singular integral on the computation of the vertical deflections. The results of the vertical deflections over China by applying the spherical 1D FFT formula with different integration radii have been compared to the astro-observed vertical deflections in the South China Sea to obtain a set of optimum deflection computation parameters.     

Experimental study on the seismic performance of new sandwich masonry walls

Sandwich masonry walls are widely used as energy-saving panels since the interlayer between the outer leaves can act as an insulation layer.New types of sandwich walls are continually being introduced in research and applications,and due to their unique bond patterns,experimental studies have been performed to investigate their mechanical properties,especially with regard to their seismic performance.In this study,three new types of sandwich masonry wall have been designed,and cyclic lateral loading tests were carried out on five specimens.The results showed that the specimens failed mainly due to slippage along the bottom cracks or the development of diagonal cracks,and the failure patterns were considerably influenced by the aspect ratio.Analysis was undertaken on the seismic response of the new walls,which included ductility,stiffness degradation and energy dissipation capacity,and no obvious difference was observed between the seismic performance of the new walls and traditional walls.Comparisons were made between the experimental results and the calculated results of the shear capacity.It is concluded that the formulas in the two Chinese codes(GB 50011 and GB 50003) are suitable for the calculation of the shear capacity for the new types of walls,and the formula in GB 50011 tends to be more conservative.     

用无味变换法求解交会测量及其协方差传播

在交会测量中,交会角的测量误差会使得定位结果具有不确定性,定位坐标的均值和协方差用于表示定位结果及其不确定度。首先对基于一阶Taylor级数展开的前方交会测量及其协方差传播进行研究,分析发现该方法仅具有一阶精度,特别是在测量误差较大的场合,该方法精度较低。然后将无味变换方法用于前方交会测量定位问题,使定位精度、协方差传播精度均提高到二阶以上。最后通过数值仿真验证了无味变换方法在定位精度以及协方差传播精度方面的优势。     

面向冰冻圈服务功能核算的西藏公路经济增长贡献及空间效应

为面向冰冻圈服务功能核算,采用投入产出法和ESDA分析,评估了2012-2016年间西藏自治区公路交通基础设施建设对经济增长的贡献程度,并解释作用机理,在此基础上运用GlobalMoran's I指数和Local Moran's I指数作出空间效应分析。结果表明：公路建设直接和间接创造的增加值对区域经济增长具有巨大的促进作用,在空间分布上,各地市公路建设对经济增长的贡献度在自治区范围内存在差异,但未呈现出固定的变化趋势。由于公路对经济增长巨大的溢出效应,应高度重视公路等交通基础设施建设,加大投资力度,拓展通达里程与空间分布,在冰冻圈服务功能核算中纳入交通设施建设的社会经济效益,同时充分考虑冰冻圈气候变化等因素对交通基础设施的危害影响,确保区域经济保持平稳快速增长。     

喀喇昆仑山厦呈、吕莫慕士塔格山段现代冰川分布及变化特征

在全球气候普遍变暖、冰川大面积退缩的大背景下,为揭示山岳冰川十分发育的喀喇昆仑山脉现代冰川分布及变化特征,以中等空间分辨率(ETM和Landsat 8)卫星数据为主要数据源,采用人机交互式解译方法完成了厦呈慕士塔格山、吕莫慕士塔格山段冰川变化遥感调查,基本查明了区内冰川面积、分布特征和变化状况,共调查1 373处冰川,其中中国境内有554处,境外克什米尔印控区有819处; 同时对区内典型冰川变化进行了2期对比分析,得出冰舌退缩、前进或稳定现象同时存在的结论,为喀喇昆仑山脉冰川变化研究提供了参考依据,为我国西部边海防地区水资源的开发利用和冰雪灾害的防治等提供了科学依据。