Assessing spatial and attribute errors in large national datasets for population distribution models: a case study of Philadelphia county schools

Geospatial technologies and digital data have developed and disseminated rapidly in conjunction with increasing computing efficiency and Internet availability. The ability to store and transmit large datasets has encouraged the development of national infrastructure datasets in geospatial formats. National datasets are used by numerous agencies for analysis and modeling purposes because these datasets are standardized and considered to be of acceptable accuracy for national scale applications. At Oak Ridge National Laboratory a population model has been developed that incorporates national schools data as one of the model inputs. This paper evaluates spatial and attribute inaccuracies present within two national school datasets, Tele Atlas North America and National Center of Education Statistics (NCES). Schools are an important component of the population model, because they are spatially dense clusters of vulnerable populations. It is therefore essential to validate the quality of school input data. Schools were also chosen since a validated schools dataset was produced in geospatial format for Philadelphia County; thereby enabling a comparison between a local dataset and the national datasets. Analyses found the national datasets are not standardized and incomplete, containing 76 to 90 percent of existing schools. The temporal accuracy of updating annual enrollment values resulted in 89 percent inaccuracy for 2003. Spatial rectification was required for 87 percent of NCES points, of which 58 percent of the errors were attributed to the geocoding process. Lastly, it was found that by combining the two national datasets, the resultant dataset provided a more useful and accurate solution.     

城市相互作用关系的一种新模式--近域城市整合研究

市场机制下的生产要素流动以及经济发展全球化、区域集团化的走向，改变了近域城市间要么行政协调、要么纯粹竞争的传统相互关系，代之以“整合并共同繁荣”这一新的发展模式，以前期实证研究为基础，从理论上论述了城市整合的背景、理论内涵和城市不整合的状态特征；指出制度创新、生产要素互补、企业集团化、统一市场体系建设、基础设施和生态环境共享共建是近域城市整合的动力机制和“结节点”；同时还提出了“成长三角”，“雁行式”、“多极式”、“双核式”等近域城市整合发展模式。     

油、水、干层的地球化学识别

本文介绍一种判断油、水、干层的地球化学方法，根据储层样品中有机抽提的的含量和组成特征，结合油层物性，地层测试和试油资料编制织识别油、水，干层的图版，提出判别油、水、干层的地质／地球化学指标，确定油层的地球化学参数的下限，并运用此方法对松辽盆地新站油田主要油层分布段的油、水、干层进行判别。根据试油资料验证表明，地球化学判断结果比传统的地质录井及地球物理测井资料判断结果更符合实际情况。     

Reconstruction from three orthographic views

Summary As Ullman (1979) showed, an object can be reconstructed uniquely from three orthographic views, if at least four homologous tripels of points are known. If only three homologous tripels of points are observed, the reconstruction problem has a finite number of solutions (cf. Huang and Lee (1989)). In this article the 3-point-problem is reduced to a quadratic problem: If the squares of the sides of the considered triangles are interpreted as coordinates in a three-dimensional parameter space, the reconstruction problem is equivalent to the determination of the intersection of three parallelly shifted cones subject to certain constraints.     

Magnetic field measurements in India during the last two centuries

Summary The direction of the geomagnetic field has changed substantially less in India than in Europe since the end of the 18th century.Whereas the European geomagnetic time series indicate a tendency of secular variation from which a remarkable westward drift of the non-axial field can be deduced, in India the field direction seems to have remained more or less fixed over the last two centuries. The drift of the non-axial field seems to be very small, or even eastward.     

Administrative division system changes and urbanization in China

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Correlation of Plio-Pleistocene deposits of the Lower Rhine Basin (North-West Germany) and the Valle Ricca pits (Central Italy)

Biostratigraphic and palaeomagnetic research has been carried out on selected profiles in North-Western Germany and Central Italy in order to correlate Plio-Pleistocene sections.Around the Réunion subchronozone, vegetation in the Valle Ricca was dominated by a mountain forest type pointing to cool climatic conditions. In the Lower Rhine Basin vegetation had a slightly warmer character, but was also dominated strongly by a mountain type of forest vegetation, characteristic of cooler summers and higher precipitation than at present.Two warmer periods have been determined in the Central Italian profiles; the youngest around the Olduvai reversal, should correspond to the youngest Tiglian beds of the Lower Rhine Basin.Deposits older than the Réunion subzone have not been found in the Valle Ricca. In the Lower Rhine Basin, on the other hand, the Gauss-Matuyama boundary is located between the uppermost Pliocene, the Reuverian C and the Praetiglian.     

Selection criteria for continuous channel electron multipliers in space applications

Criteria for selecting continuous channel electron multipliers were applied to fifteen Mullard units without significantly affecting their overall lifetime. The gain fatigue vs accumulated counts, the change of the pulse height distribution during lifetime, the gain degradation vs count rates as well as the gain vs operating voltage and the resolution vs operating voltage have been investigated using a tritium source. The results provide several criteria to determine good, marginal and poor multipliers. From all tested devices 25% had a very low gain and did not operate satisfactory at the end of their lifetime investigations (4×10⁹ accumulated counts). 40% of all devices could be classified as good multipliers. Their main characteristic was a gain recovery phenomenon after 3×10⁹ accumulated counts with a progressive gain stabilizing. Multipliers classified as marginal exhibited some unexpected behaviour during the lifetime but a gain recovery phase and gain plateau region could be identified. Furthermore, the relative efficiency of the multipliers vs electron energy as a function of the operating voltage has been measured by using a near monoenergetic electron beam.Originally submitted to the journalSpace Science Instrumentation.     

Transboundary impacts on regional ground water modeling in Texas

Recent legislation required regional grassroots water resources planning across the entire state of Texas. The Texas Water Development Board (TWDB), the state's primary water resource planning agency, divided the state into 16 planning regions. Each planning group developed plans to manage both ground water and surface water sources and to meet future demands of various combinations of domestic, agricultural, municipal, and industrial water consumers. This presentation describes the challenges in developing a ground water model for the Llano Estacado Regional Water Planning Group (LERWPG), whose region includes 21 counties in the Southern High Plains of Texas. While surface water is supplied to several cities in this region, the vast majority of the regional water use comes from the High Plains aquifer system, often locally referred to as the Ogallala Aquifer. Over 95% of the ground water demand is for irrigated agriculture. The LERWPG had to predict the impact of future TWDB-projected water demands, as provided by the TWDB, on the aquifer for the period 2000 to 2050. If detrimental impacts were noted, alternative management strategies must be proposed. While much effort was spent on evaluating the current status of the ground water reserves, an appropriate numerical model of the aquifer system was necessary to demonstrate future impacts of the predicted withdrawals as well as the effects of the alternative strategies. The modeling effort was completed in the summer of 2000. This presentation concentrates on the political, scientific, and nontechnical issues in this planning process that complicated the modeling effort. Uncertainties in data, most significantly in distribution and intensity of recharge and withdrawals, significantly impacted the calibration and predictive modeling efforts. Four predictive scenarios, including baseline projections, recurrence of the drought of record, precipitation enhancement, and reduced irrigation demand, were simulated to identify counties at risk of low final ground water storage volume or low levels of satisfied demand by 2050.