The harmonic representation of the disturbing potential

Summary The alternative harmonic representations of the disturbing potential, correct to the order of the flattening, are examined and an example is given where the incorrect use of a spherical harmonic expansion can give rise to fallacious results. The correct usage of the spherical harmonic expansion for the disturbing potential is given in the solution of the general surface integral to define the indirect effect in the case of the non-regularised geoid.     

Spatial autocorrelation and the sensitivity of RESET: a simulation study

Ramsey’s regression specification error test (RESET) is thought to be robust to spatial correlation. Building on the literature on spurious spatial regression, we show that this is not so in presence of spatial correlation in both the error and the independent variable of an econometric model. Correcting the test for spatial correlation improves its performance, though in large samples this strategy is not completely successful. Once assuming that spatial autocorrelation in both the independent variable and in the error is produced by a spatial moving average model instead of a spatial autoregressive one, RESET displays more robustness.     

Theory of the local scale parameter method for EDM

The determination of a representative refractive index for the wave path is the main limitation of the attainable accuracy in electronic distance measurement. To overcome this limitation the length ratio method was initially proposed and later developed into the local scale parameter (LSP) method. In this paper, the mathematical model of the LSP method is derived for electro-optical distance measurement from first principles based on the physics of the atmospheric boundary layer. The model does not rely on standard atmospheres. It is shown that atmospheric temperatures and pressures must be observed at instrument stations but not at reflector stations. Appropriate LSP field procedures and the results of some field experiments are summarized. The method consistently produces accuracies of better than ±1 ppm. Use of the method is recommended for high precision (trilateration) networks, which need to be measured repeatedly and where absolute scale is not relevant.     

Modeling and sensitivity analysis of navigation parameter errors for airborne synthetic aperture radar stereo geolocation

For the high-resolution airborne synthetic aperture radar (SAR) stereo geolocation application, the final geolocation accuracy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geolocation errors for ground target points. In addition, utilizing true flight track parameters’ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.     

Modeling and sensitivity analysis of navigation parameter errors for airborne synthetic aperture radar stereo geolocation

For the high-resolution airborne synthetic aperture radar (SAR) stereo geolocation application, the final geolocation accuracy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geolocation errors for ground target points. In addition, utilizing true flight track parameters’ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.     

Effects of scale in spatial interaction models

We study the effects of aggregation on four different cases of nonlinear spatial gravity models. We present some theoretical results on the relationship between the mean flows at an aggregated level and the mean flow at the disaggregated level. We then focus on the case of perfect aggregation (scale problem) showing some results based on the theoretical expressions previously derived and on some artificial data. The main aim is to test the effects on the aggregated flows of the spatial dependence observed in the origin and in the destination variables. We show that positive spatial dependence in the origin and destination variables moderate the increase of the mean flows connatural with aggregation while negative spatial dependence exacerbates it.     

中小比例尺下居民地综合及冲突处理

针对中小比例尺地形图上的散列式居民地较难进行自动化综合缩编的问题,该文对中小比例尺地形图上散列式居民地的综合过程及其冲突处理方法进行了研究。首先,通过探测邻近关系和分析空间特征,对居民地进行合并和选取,减少目标数,控制数量变化;进一步地通过模板匹配对单一的目标进行形状化简,控制表达变化。同时,针对其综合处理和符号化过程中可能出现的空间冲突,提出了基于Delaunay三角网模型的探测和处理方法。最后,给出了一套中小比例尺地形图上居民地要素的综合处理策略。该研究成果可规模化应用于中小比例尺综合缩编生产实践。     

多尺度表达中空间拓扑关系等价性评价模型

本文主要讨论不同尺度下地理目标之间拓扑关系的等价性问题。根据人类认知习惯,得出从大比例尺地理空间中拓扑关系抽象为小比例尺空间中拓扑关系应当遵循的基本规则,并利用模糊函数将这些规则定量化;在此基础上,得到评价地理空间场景中多个空间目标之间拓扑关系在不同尺度下是否等价的综合评价模型。该模型可以用于检验和维护空间数据质量、为地图自动综合提供空间关系处理和评价方法的参考。     

Spatial analysis of groundwater potential using remote sensing and GIS in the Kanyakumari and Nambiyar basins,India

Remotely sensed data can provide useful information in understanding the distribution of groundwater, an important source of water supply throughout the world. In the present study, the modern geomatic technologies, namely remote sensing and GIS were used in the identification of groundwater potential zones in the Kanyakumari and Nambiyar basins of Tamil Nadu in India. The multivariate statistical technique was used to find out the relationship between rainfall and groundwater resource characteristics. It has been found out that groundwater not only depends upon rainfall, but various other factors also influence its occurrence. Eight such parameters were considered and multi criterion analysis has been carried out in order to find out the potential zones. Accordingly, it had been concluded that the Kanyakumari river basin has more ground water potential, whereas the Nambiyar basin has less potential. Thus surface investigation of groundwater has proved to be easier, time consistent and cheaper using the geomatic technologies.     

Spatial analysis of an urban flash flood survey results

The geographical distribution of a flash flood's occurrence could be an important consideration in assessing its severity and social impacts. In this study, the spatial distribution of survey responses is analysed with respect to features such as the stream network (natural water path), the drainage network, buildings, and catchments. This provides information on both flash flood distribution causes in an urban setting and residents' perceptions of the hazard that would otherwise not be revealed. The study demonstrated the possibility of taking into account people's experience in detecting the location of potential flash flood hazards. It also illustrates the usefulness of GIS-supported spatial analysis of survey results in identifying factors that increase the occurrence of urban flash floods.     

A local approach to optimize the scale parameter in multiresolution segmentation for multispectral imagery

The results obtained using the object-based image analysis approach for remote sensing image analysis depend strongly on the quality of the segmentation step. In this paper, to optimize the scale parameter in a multiresolution segmentation, we analyse a high-resolution image of a large and heterogeneous agricultural area. This approach is based on using a set of agricultural plots extracted from official maps as uniform spatial units. The scale parameter is then optimized in each uniform spatial unit. Intra-object and inter-object heterogeneity measurements are used to evaluate each segmentation. To avoid subsegmentation, some oversegmentation is allowed, but is attenuated in a second step using the spectral difference segmentation algorithm. The statistical distribution of the scale parameter is not equal in all land uses, indicating the soundness of this local approach. A quantitative assessment of the results was also conducted for the different land covers. The results indicate that the spectral contrast between objects is larger with the local approach than with the global approach. These differences were statistically significant in all land uses except irrigated fruit trees and greenhouses. In the absence of subsegmentation, this suggests that the objects will be placed far apart in the space of variables, even if they are very close in the physical space. This is an obvious advantage in a subsequent classification of the objects.     

极坐标法在非量测相机检校场控制测量中的应用

分析室内检校场精度的常用测量控制方法,将极坐标应用于非量测相机检校场控制测量精度分析,研究其控制过程和精度误差。通过应用于铁路隧道衬砌表面状态检测与隧道限界测量系统,证明了文中方法具有较高的控制精度,可以满足一般工业摄影测量任务的需要。     

Spatial dependency of cholera prevalence on potential cholera reservoirs in an urban area,Kumasi, Ghana

Cholera has been a public health burden in Ghana since the early 1970s. Between 1999 and 2005, a total of 25,636 cases and 620 deaths were officially reported to the WHO. In one of the worst affected urban cities, fecal contamination of surface water is extremely high, and the disease is reported to be prevalent among inhabitants living in close proximity to surface water bodies. Surface runoff from dump sites is a major source of fecal and bacterial contamination of rivers and streams in the study area. This study aims to determine (a) the impacts of surface water contamination on cholera infection and (b) detect and map arbitrary shaped clusters of cholera. A Geographic Information System (GIS) based spatial analysis is used to delineate potential reservoirs of the cholera vibrios; possibly contaminated by surface runoff from open space refuse dumps. Statistical modeling using OLS model reveals a significant negative association between (a) cholera prevalence and proximity to all the potential cholera reservoirs (R² = 0.18, p < 0.001) and (b) cholera prevalence and proximity to upstream potential cholera reservoirs (R² = 0.25, p < 0.001). The inclusion of spatial autoregressive coefficients in the OLS model reveals the dependency of the spatial distribution of cholera prevalence on the spatial neighbors of the communities. A flexible scan statistic identifies a most likely cluster with a higher relative risk (RR = 2.04, p < 0.01) compared with the cluster detected by circular scan statistic (RR = 1.60, p < 0.01). We conclude that surface water pollution through runoff from waste dump sites play a significant role in cholera infection.     

1：5万矢量地形数据空间拓扑关系的自动检查方法

本文论述了1：5万矢量地形数据空间拓扑关系自动检查的必要性，提出了拓扑关系检查的内容、方法和过程，并应用到1：5万矢量地形数据库的建库工作中．     

单窗算法和单通道算法对参数估计误差的敏感性分析

单窗算法和单通道算法的提出为应用LandsatTM热波段反演地表温度开辟了新途径。由于进行地面像元尺度同步温度测量难度较大,目前尚无法对这两种算法进行直接评判。通过对算法所需参数分别取一定变动区间并进行渐变取值测算,分析了算法对其参数估计误差的敏感性,以此作为对这两种算法适用性的一个间接评判依据。     

Spectral representation and analysis of the KBR precision based on the earth gravity spectrum

Satellite-to-Satellite Tracking in low-low model (SST-ll) is a new technique to resolve the series of problems met in the determination of the earths gravity field. As the key technique of SST-ll, KBR can get SST-ll measurements directly. So the KBR performance analysis is the first step in SST-ll design. In this paper, assuming that the satellite pairs of SST-ll are in near circle polar orbits, the spectrum relationship between the earth gravity field and KBR is established using analytic method. And then some examples are analyzed, the suggestions and conclusions are drawn from these examples. The research results could be taken as a reference for future satellite gravity project of China.     

Spectral Representation and Analysis of the KBR Precision Based on the Earth Gravity Spectrum

IntroductionThe GRACE (gravity recovery and cli mate ex-peri ment) mission,twin satellites flying in for-mation ,which carries several key payloadsinclu-ding KBR (K-band ranging) system, waslaunchedin 2002 . The unique design of GRACEmissionis expected to lead to ani mprovement inseveral orders of magnitude in these gravitymeasurements and allow much i mproved resolu-tion of the Earth gravity field of finer scale overbothland and ocean to study a lot of geosciencesphenomena[1]. Though th…     

A scoping review on the multiplicity of scale in spatial analysis

Journal of Geographical Systems - Scale is a central concept in the geographical sciences and is an intrinsic property of many spatial systems. It also serves as an essential thread in the fabric...     

中国人口分布及空间相关分析

利用2000年人口普查信息,介绍了在人口地理信息系统中,通过三维模型显示,罗伦斯曲线,人口重心和人口潜力等方法,分析中国人口分布的特征。在此基础上,用空间相关方法对人口分布的现象进行分析,揭示了其空间地理分布的内在联系。