LandScan USA: a high-resolution geospatial and temporal modeling approach for population distribution and dynamics   总被引：8，自引：0，他引：8  

Budhendra Bhaduri  Edward Bright  Phillip Coleman  Marie L. Urban 《GeoJournal》2007,69(1-2):103-117

High-resolution population distribution data are critical for successfully addressing important issues ranging from socio-environmental research to public health to homeland security, since scientific analyses, operational activities, and policy decisions are significantly influenced by the number of impacted people. Dasymetric modeling has been a well-recognized approach for spatial decomposition of census data to increase the spatial resolution of population distribution. However, enhancing the temporal resolution of population distribution poses a greater challenge. In this paper, we discuss the development of LandScan USA, a multi-dimensional dasymetric modeling approach, which has allowed the creation of a very high-resolution population distribution data both over space and time. At a spatial resolution of 3 arc seconds (～90 m), the initial LandScan USA database contains both a nighttime residential as well as a baseline daytime population distribution that incorporates movement of workers and students. Challenging research issues of disparate and misaligned spatial data and modeling to develop a database at a national scale, as well as model verification and validation approaches are illustrated and discussed. Initial analyses indicate a high degree of locational accuracy for LandScan USA distribution model and data. High-resolution population data such as LandScan USA, which describes both distribution and dynamics of human population, clearly has the potential to profoundly impact multiple domain applications of national and global priority.  相似文献   

A continuum representation of fracture networks. Part I: Method and basic test cases     

Urban Svensson 《Journal of Hydrology》2001,250(1-4):170-186

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AN IMPROVED SEMI-IMPLICIT TIME DIFFERENCE SCHEME OF SPECTRAL MODEL AND NUMERICAL APPLICATIONS   总被引：1，自引：0，他引：1  

张朝林  yahoo.com.  郑庆林  宋青丽 《Acta Meteorologica Sinica》2002,(2)

In fact,the popular semi-implicit time difference scheme of spectral model still includes someimportant linear terms using time explicit difference scheme,and the major terms are directlyrelated to fast internal-and external-gravity waves in the atmospheric forecasting equation.Additionally,due to using time difference on two terms at different time.the popular schemeartificially introduces unbalance between pressure gradient force and Coriolis force terms whilenumerically computing their small difference between large quantities.According to thecomputational stability analysis conducted to the linear term time difference scheme in simpleharmonic motion equation,one improved semi-implicit time difference scheme is also designed inour study.By adopting a kind of revised time-explicit-difference scheme to these linear terms thatstill included in spectral model governing equations,the defect of spectral model which only partlyusing semi-implicit integrating scheme can be overcome effectively.Moreover,besides all spectralcoefficients of prognostic equations,especially of Helmholtz divergence equation,can be workedout without any numerical iteration,the time-step (computation stability) can also be enlarged(enhanced) by properly introducing an adjustable coefficient.  相似文献   

Conceptualizing Anthropogenic Change in Fluvial Systems: Drainage Development on the Upper Embarras River,Illinois   总被引：1，自引：0，他引：1  

Michael A. Urban 《The Professional geographer》2002,54(2):204-217

While the geomorphic structure of many landscapes is materially molded, shaped and transformed by human practices, it is at the same time experienced and perceived through the mediation of cultural discourse and representation. The objective of this article is twofold: (1) to establish a conceptual framework for integrated analysis of human and geomorphic dimensions of landscape change; and (2) to illustrate the use of this framework in the assessment of a physical system severely affected by human agency. This perspective offers one way in which human agency can be synthesized and integrated into aspects of physical geography— specifically fluvial geomorphology— from both a conceptual and a pragmatic point of view. The upper Embarras River in east central Illinois, used as a case study, has been and continues to be physically affected by the cultural practice of agricultural drainage over the past century and a half.  相似文献   

Are we measuring concern about global climate change correctly? Testing a novel measurement approach with the data from 28 countries     

Jan Urban 《Climatic change》2016,138(3-4):397-410

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Sampling the Chemistry of Shallow Aquifer Systems — A Case Study     

H. B. Pionke  J. B. Urban 《Ground Water Monitoring & Remediation》1987,7(2):79-88

Pumped waters from 14 Pennsylvania wells, located in shallow sandstone, siltstone and shale aquifers, were continuously monitored for dissolved oxygen (D. O.), nitrate (NO₃), pH, electrical conductivity (EC) and water temperature in a discharge manifold at the well head. The amount of pumping or purging required to stabilize these parameter readings varied by well site and parameter being analyzed. However, the purging required was generally greatest for D. O. and least for water temperature where: D. O. < NO₃ pH < EC < water temperature. Wells located near the siltstone-shale interface generally required far more purging than did wells located elsewhere. Although parameter stability was often achieved within purging one bore volume, the complexity, diversity, and variability in the data and these well-ground water systems, suggest that no single purging rule is appropriate. Instead, the extent of purging required before sampling these shallow aquifers should be determined by incorporating on-site monitoring of target or related parameters into the purging process.
From a sampling perspective, the relationship between NO₃ and D. O. concentrations during purging were analyzed relative to aquifer type. For most wells located in sandstone or siltstone, NO₃ concentrations remained relatively constant during purging irrespective of changes in D. O. For most wells located in shale, these two were positively and similarly correlated, suggesting that a general relationship exists.  相似文献   

In-situ fluid-pressure measurements for earthquake prediction: An example from a deep well at Hi Vista,California   总被引：1，自引：0，他引：1  

John H. Healy  T. C. Urban 《Pure and Applied Geophysics》1984,122(2-4):255-279

Short-term earthquake prediction requires sensitive instruments for measuring the small anomalous changes in stress and strain that precede earthquakes. Instruments installed at or near the surface have proven too noisy for measuring anomalies of the size expected to occur, and it is now recognized that even to have the possibility of a reliable earthquake-prediction system will require instruments installed in drill holes at depths sufficient to reduce the background noise to a level below that of the expected premonitory signals. We are conducting experiments to determine the maximum signal-to-noise improvement that can be obtained in drill holes. In a 592 m well in the Mojave Desert near Hi Vista, California, we measured water-level changes with amplitudes greater than 10 cm, induced by earth tides. By removing the effects of barometric pressure and the stress related to earth tides, we have achieved a sensitivity to volumetric strain rates of 10^–9 to 10^–10 per day. Further improvement may be possible, and it appears that a successful earthquake-prediction capability may be achieved with an array of instruments installed in drill holes at depths of about 1 km, assuming that the premonitory strain signals are, in fact, present.  相似文献   

Zur Kenntnis der präkambrischen,schichtgebundenen Molybdänitvorkommen in Südnorwegen     

Abteilungsleiter Dr. Hans Urban 《International Journal of Earth Sciences》1974,63(1):180-190

The southern Norwegian molybdenum deposits have hitherto been looked upon as typical examples of deposits of pneumatolytic — catathermal origin formed by emanations from intrusive granites. It is now demonstrated that all these deposits are to be found stratabound in a series of grey gneisses. They are accompanied by varying amounts of graphite and apatite of biogenetic origin and all of them show the same sulphide and oxide ore mineral paragenesis. It is concluded that the concentration and precipitation of metals took place in marine environments. Both the ores and their host rocks later underwent the same highmetamorphic processes.  相似文献   

Geomagnetic field: Contribution of higher harmonics to the variations of virtual pole positions     

A. Janáčková  L. Urban 《Studia Geophysica et Geodaetica》1990,34(4):382-387

Summary On the basis of the 1945 IGRF two sets of virtual geomagnetic poles have been computed and compared. The first set refers to a realistic model of the field; these virtual poles are all located in the north polar area. The second set refers to an artificial field containing higher harmonics only; these virtual poles are distributed over the Earth's surface as a whole. However both sets of virtual poles yield similar distributions of values of their space (and probably also time) variations.  相似文献   

The lower carboniferous black shale formation,a possible source for noble and base metal deposits in the NE Rhenish Massif,Federal Republic of Germany     

Dr. B. Stribrny  Prof. Dr. H. Urban  Dipl.-Min. H. Weber 《Mineralogy and Petrology》1988,39(2):129-143

Summary In the northeastern Rhenish Massif the Lower Carboniferous black shale formation, comprising black shales, black lydites, siliceous limestones and clayshales, host low concentrations of stratabound sulfides, which are interpreted as sedimentary-exhalative depositions. Intraformational mobilizations and migrations of metals and their reprecipitation in physico-chemical traps led locally to minable ores. Further metal concentration has been caused by supergene processes.

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Die unterkarbonische Schwarzschieferserie: potentielle Muttergesteine für Edel- und Buntmetall-Vorkommen im nordöstlichen Rheinischen Schiefergebirge, Bundesrepublik Deutschland

Zusammenfassung Im nordöstlichen Rheinischen Schiefergebirge treten in der unterkarbonischen Schwarzschieferserie, die sich aus Schwarzschiefern, schwarzen Lyditen, Kieselkalken und Tonschiefern zusammensetzt, geringe Konzentrationen an schichtgebundenen Sulfiden auf. Die schichtgebundenen Sulfide werden als sedimentär-exhalative Bildungen gedeutet. Intraformationale Mobilisationen und Migrationen von primär in Sulfiden fixierten Metallen sowie deren Wiederabsetzung in physikalisch-chemischen Fallen führten lokal zur Bildung von bauwürdigen Erzen. Weitere Anreicherungen erfolgten teilweise durch supergene Prozesse.

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