交叉型报表技术在GIS中的应用

分析了交叉型报表模版单元的内部结构,探寻了将ＳＱＬ语句嵌入交叉型报表表模版的基本单元,实现了报表快速自动创建的技术。     

Assessing the spatial distribution of crop areas using a cross-entropy method

While crop production statistics are reported on a geopolitical – often national – basis, we often need to know, for example, the status of production or productivity within specific sub-regions, watersheds, or agro-ecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to the plausible estimates of the spatial distribution of crop areas. Using this approach tabular crop production statistics are blended judiciously with an array of other secondary data to assess the areas of specific crops within individual ‘pixels’—typically 25–100 km² in size. The information utilized includes crop production statistics, farming system characterization, satellite-based interpretation of land cover, biophysical crop suitability assessments, and population density. An application is presented in which Brazilian state level production statistics are used to generate pixel level crop area data for eight crops. To validate the spatial allocation we aggregated the pixel estimates to obtain synthetic estimates of municipality level areas in Brazil, and compared those estimates with actual municipality statistics. The approach produced extremely promising results. We then examined the robustness of these results compared to simplified approaches to spatializing crop production statistics and showed that, while computationally intensive, the cross-entropy method does provide more reliable spatial allocations.     

The autocorrelation of waveforms generated from ocean-scattered GPS signals

A "waveform" is generated by cross-correlating local copies of a global positioning system (GPS) signal with an ocean-reflected GPS signal, over a range of carrier frequencies and code delays. The shape of this waveform can be inverted to obtain estimates of the ocean surface roughness. To assess the accuracy of these retrievals, a stochastic model for the waveform time series measurements was developed in a previous publication. In this letter, this model is validated by comparing the predicted autocorrelation function of the waveform against the autocorrelation computed from experimental waveforms collected from an airborne receiver. A 1-ms coherent integration time was used at first. Then, blocks of these measurements were concatenated to produce equivalent integration times of up to 5 ms to compare the dependence of model predictions on integration time. Correlation time was estimated by fitting a model Gaussian function to the magnitude or the real part of the autocorrelation function. The magnitude and phase of the complex autocorrelation function from the model were also studied to show the location of the first , and better explain cases in which the Gaussian function did not fit well. The autocorrelation is found to be weakly dependent upon the surface roughness, over a range of moderate wind speeds.     

Environmental sustainability and scenarios of urbanization in arid area

Based on data of questionnaire and field survey and two developing models of Business As Usual (BAU) and the Intensive Urbanization (IU), this article, taking Wuwei City, a medium size city and typical oasis arid area in Gansu Province with very vulnerable and sensitive natural environment but long history of oasis economy, as an example, evaluated the sustainability of its environment and analyzed the scenarios of Wuwei’s household energy consumption, waste discharge in transportation industry, primary industry, secondary industry, tertiary industry, by the integration of the systematical dynamics model Stella and Polestar language to simulate the future development of the research area. The results showed that, first, the developing model of IU was propitious to Wuwei City named for oasis economy and vulnerable natural environment. The strategy of "Intensive Urbanization" can change the structure of energy utilization, and improve the efficiency of energy utilization. Second, the proportion of domestic energy consumption will decrease with industrialization and economic development, while that of tertiary industry, secondary industry and transportation will gradually grow up according to strategy of "Intensive Urbanization". Third, the Wuwei City is facing a severe eco-environmental crisis under the conventional patterns of development and a better future under a sustainable urbanization scenario, in the next 10 to 20 years. The different developing trends were clarified and the relative countermeasures were put forward for the policy makers according to the driving forces. Foundation item: Under the auspices of Key Program of the National Natural Science Foundation of China (No. 90102013) and Key Innovation Sub-project of Chinese Academy of Sciences (No. KZCX1-10-07-04) Biography: YOU Fei (1972–), male, a native of Pianguan of Shanxi Province, Ph.D., assistant professor, specialized in regional sustainable development and ecological economy. E-mail: yofae@sina.com     

青藏高原1993年GPS观测成果的精度分析

应用线性回归、符号检验等数理统计方法研究了１９９３年完成的跨青藏高原首期ＧＰＳ网３９条基线的数据处理结果。通过对单基线观测中误差、重复观测基线互差及异步环闭合差的精度分析，认为由１６个观测点组成的跨青藏高原ＧＰＳ监测网的基线平均相对精度达０．１ｐｐｍ。     

三峡二期工程蓄水后的垂直形变场

根据三峡地区的数字高程模型(DEM)，模拟三峡二期工程蓄水位达到135m后的水体负载，利用Farrell提出的质量负荷产生的地球形变理论，推算三峡水库水位达到135m后整个库区的垂直形变，与三峡库区GPS形变监测网获得的蓄水前后的垂直形变图像进行对比分析，结果显示：在三斗坪-巴东库段，两者中都出现了3个相同的、明显的垂直形变集中区。在三峡大坝附近，模拟结果比观测结果大8～15mm，说明坝址附近的花岗岩具有较强的刚性；而在香溪，模拟结果比观测结果要小23mm，且GPS观测到长江两岸的垂直变化差异达到22mm，说明该段地质构造的特殊性和复杂性。综合分析表明，三峡大坝坝址所在地的地质构造和地壳是稳定的。     

中国大陆地壳现今运动的GPS测量结果与初步分析

利用中国大陆及周边地区 1991～ 2 0 0 0年间一系列全球定位系统 (GPS)观测资料 ,计算了 340个GPS站点的位移速率 ,得到了统一的中国大陆现今地壳运动速率场。这些站主要集中于青藏高原及其周缘的喜马拉雅、川滇、河西走廊、阿尔金、天山 ,以及华北、福建东南沿海等主要构造活动区。固定测站速率精度优于 1mm/a ,流动测站速率精度优于 3mm/a。根据GPS结果对中国大陆现今地壳运动的状况进行了分析。     

Research on Relationship between Elastic and Plastic Deformation of Material

Based on a lot of experiment results, it is put forward that the elastic part and plastic part of deformation of general metal material, and isotropic homogeneous, and continuous rock material follow a law—the relative law of elastic and plastic deformation. The law results from testing study and is partly proved theoretically.     

长江三峡工程诱发地震监测系统中的GPS监测网及其观测结果

阐述长江三峡工程诱发地震监测系统中的 GPS监测网的设计思路 ,并介绍了该网的第一、二期观测情况及数据处理结果。认为该网无论是技术设计还是运行质量 ,均达到世界一流的先进水平 ,其站间基线长度及其分量的测定精度优于 5mm。