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In this article we draw on the power of geographic information systems (GIS) to examine the progression of HIV/AIDS in Africa for the period from 1986 to 2003. We use GIS for two purposes: (1) to transform and interpolate a set of annual point-based HIV/AIDS rates into area data; and (2) to extract or “mine” annual HIV/AIDS prevalence rates from the interpolated area (country) level maps. Once the rates are extracted from the GIS analysis we then model and forecast them into the near future (i.e., 2004–2010) by using the UNAIDS Estimation and Projection Package (EPP) software. The article offers an alternative grounded in geospatial analysis for yielding estimates of HIV/AIDS rates in Africa. Using incomplete sets of data for the period from 1986 to 2003, mean HIV/AIDS rates are generated from spatially interpolated data and future trends are estimated. The results indicate that the HIV/AIDS epidemic for many countries in Africa has reached the saturation or maturity level as evidenced by the typical S-shaped curves in the trends over time. As a matter of fact, some countries have begun to experience a sustained decline in the rates (e.g., Uganda, Burundi, Rwanda, and Zimbabwe). 相似文献
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高校专业课的课程思政建设是高校思想政治工作的基本载体。“地图学”是测绘工程、遥感科学与技术、地理信息科学、地理科学等本科专业的基础课,在测绘、地理等学科的课程思政建设中具有基础性地位。本文依据教学实践,归纳了地图学课程中与课程思政相结合的知识点,并介绍了在教学中如何巧妙、潜移默化地融入思政元素,在地图学课程教学过程中做到能力培养和素质提升共同进步。 相似文献
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在铁路测量中,长度投影变形要求小于2.5cm/km。但是由于铁路为典型的线性工程,通常横跨多个投影带,因此采用国家标准3。带难以满足铁路测量精度要求,本文通过分析高斯投影长度变形,提出分段建立独立坐标系的方法,控制长度投影变形,满足精度要求,最后介绍利用GlobalMapper软件实现两个独立坐标系的转换。 相似文献
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The topographic mapping products of airborne light detection and ranging (LiDAR) are usually required in the national coordinates (i.e., using the national datum and a conformal map projection). Since the spatial scale of the national datum is usually slightly different from the World Geodetic System 1984 (WGS 84) datum, and the map projection frame is not Cartesian, the georeferencing process in the national coordinates is inevitably affected by various geometric distortions. In this paper, all the major direct georeferencing distortion factors in the national coordinates, including one 3D scale distortion (the datum scale factor distortion), one height distortion (the earth curvature distortion), two length distortions (the horizontal-to-geodesic length distortion and the geodesic-to-projected length distortion), and three angle distortions (the skew-normal distortion, the normal-section-to-geodesic distortion, and the arc-to-chord distortion) are identified and demonstrated in detail; and high-precision map projection correction formulas are provided for the direct georeferencing of the airborne LiDAR data. Given the high computational complexity of the high-precision map projection correction approach, some more approximate correction formulas are also derived for the practical calculations. The simulated experiments show that the magnitude of the datum scale distortion can reach several centimeters to decimeters for the low (e.g., 500 m) and high (e.g., 8000 m) flying heights, and therefore it always needs to be corrected. Our proposed practical map projection correction approach has better accuracy than Legat’s approach,1 but it needs 25% more computational cost. As the correction accuracy of Legat’s approach can meet the requirements of airborne LiDAR data with low and medium flight height (up to 3000 m above ground), our practical correction approach is more suitable to the high-altitude aerial imagery. The residuals of our proposed high-precision map projection correction approach are trivial even for the high flight height of 8000 m. It can be used for the theoretical applications such as the accurate evaluation of different GPS/INS attitude transformation methods to the national coordinates. 相似文献
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ABSTRACT A geometric algorithm for Tilted-Camera Perspective (TCP) projection is proposed in this paper based on the principle of perspective projection. According to that, the difference between TCP projection and External Perspective (EXP) projecton is analyzed. It is put forward prerequisites making these two projections were compatible, and some examples are given. 相似文献
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