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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd.
    The @journal of American culture 22 (1999), S. 0 
    ISSN: 1542-734X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: English, American Studies
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 33 (1995), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Cross-sectional, finite-difference, steady-state ground-water-flow models of a generalized New England landscape were constructed to examine the effects of hydraulic conductivity and topography on bulk-fluid flow processes in fractured crystalline rock. The generalized landscape consists of a flat hilltop, a hillside that has a slope of 0.17 ft/ft, and a flat river valley. It includes three hydrogeologic units, stratified drift in the river valley, glacial till, and underlying crystalline rock.Distribution of recharge to and discharge from bedrock is affected by the presence of small topographic features, such as terraces on the hillside. Most of these terraces consist partly or entirely of sand, and they create localized areas of recharge to and discharge from bedrock. Maximum recharge to bedrock commonly occurs at downward inflections of the water table, and discharge occurs at upward inflections of the water table. These inflections of the water table are associated with inflections in topography because the shallow depth of water on hilltops and hillsides resemble the configuration of the land surface.Regional ground-water flow in crystalline rock and distribution of bedrock recharge and discharge are also affected by heterogeneities in hydraulic conductivity of the bedrock. Vertical heterogeneity creates short, shallow flow paths in high-relief terrain. Horizontal heterogeneity causes large variations in the size of bedrock recharge areas; in some cases the difference from homogeneous conditions is more than 50 percent.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Hydrographs of stream discharge were analyzed to determine ground-water recharge for two small basins draining into Mirror Lake, New Hampshire. Two methods of hydrograph analysis developed for determining ground-water recharge were evaluated, the instantaneous recharge method and the constant recharge method. For the instantaneous recharge method, recharge is assumed to be instantaneous and uniform over the basin. For the constant recharge method, recharge is assumed to be constant and uniform over the basin for a period of weeks to months. Both methods require that a ground-water recession slope be determined. The recession slope is used directly in the calculation for the instantaneous recharge method, and it is used as a base of reference for fitting a type curve in the constant recharge method. Results of the study indicated that the estimates of ground-water recharge for both methods agree to within about 10 percent. Two approaches to the instantaneous recharge method, manual and automated, were also evaluated, and the results were statistically similar.The baseflow component of streamflow commonly is assumed to be equivalent to ground-water recharge; therefore, two methods developed for determining the baseflow component of streamflow, graphical partitioning and digital filtering, were evaluated also. Baseflow values determined by graphical partitioning of hydrographs were about 25 percent less than the ground-water recharge values. Baseflow values determined by two different approaches to the mathematical digital filtering method were generally less than baseflow determined by graphical partitioning. However, one of the approaches to digital filtering agreed reasonably well with graphical partitioning if an appropriate filter constant was used. The other approach to digital filtering resulted in baseflow values that were much less than the other baseflow values and was therefore deemed inappropriate for use on these small mountain watersheds.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Cambridge University Press
    International labor and working class history 50 (1996), S. 169-173 
    ISSN: 0147-5479
    Source: Cambridge Journals Digital Archives
    Topics: History , Sociology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Neurofibromatose I ; Segmentale Neurofibromatose ; Erblichkeit-Somatische Mutation ; Blaschko-Linien ; Key words Neurofibromatosis I ; Segmental neurofibromatosis ; Heredity ; Somatic mutation ; Blaschko lines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary We describe a patient with plexiform neurofibroma and contralateral circumscribed hyperpigmentation along the lines of Blaschko. Such findings represent a form of segmental neurofibromatosis. The origin and classification of segmental neurofibromatosis and its relationship to NFI (von Recklinghausen disease) are discussed.
    Notes: Zusammenfassung Wir berichten über eine Patientin mit plexiformem Neurofibrom und kontralateraler streifenförmiger Hyperpigmentierung entlang den Blaschko-Linien. Die Entstehungsmechanismen dieser ungewöhnlichen Form einer segmentalen Neurofibromatose und die Einordnung der segmentalen Formen der Neurofibromatose I mit ihren Beziehungen zu der (NFI) (Morbus von Recklinghausen) werden diskutiert.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-1480
    Keywords: wetland hydrology ; Palmer Drought Severity Index ; Devils Lake ; Pembina River
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract From 1988 to 1992 the north-central plains of North America had a drought that was followed by a wet period that continues to the present (1997). Data on the hydrology of the Cottonwood Lake area (CWLA) collected for nearly 10 years before, and during, the recent dry and wet periods indicate that some prairie pothole wetlands served only a recharge function under all climate conditions. Transpiration from groundwater around the perimeter of groundwater discharge wetlands drew water from the wetlands by the end of summer, even during very wet years. Long-term records of a climate index (Palmer Drought Severity Index), stream discharge (Pembina River), and lake level (Devils Lake) were used to put the 17-year CWLA record into a longer term perspective. In addition, proxy records of climate determined from fossils in the sediments of Devils Lake were also used. These data indicate that the drought of 1988-92 may have been the second worst of the 20th century, but that droughts of that magnitude, and worse, were common during the past 500 years. In contrast, the present wet period may be the wettest it has been during the past 130 years, or possibly the past 500 years.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hydrogeology journal 7 (1999), S. 28-45 
    ISSN: 1435-0157
    Keywords: Key words geologic fabric ; groundwater recharge/water budget ; groundwater/surface-water relations ; general hydrogeology ; groundwater management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé Les eaux de surface sont parties intégrantes des systèmes aquifères. Les eaux souterraines interagissent avec les eaux de surface dans presque tous les types d'environnements, depuis les petits ruisseaux, les lacs et les zones humides jusqu'aux bassins versants des vallées des grands fleuves et aux lignes de côte. Il est en général admis que les zones topographiquement hautes sont des lieux de recharge des aquifères et les zones basses des lieux de décharge, ce qui est le cas des grands systèmes aquifères régionaux. La superposition de systèmes locaux, associés à des eaux de surface, à l'organisation régionale d'écoulements souterrains résulte d'interactions complexes entre les eaux souterraines et les eaux de surface dans tous les environnements, quelle que soit la situation topographique régionale. Les processus hydrologiques associés aux eaux de surface elles-mêmes, tels que des niveaux d'eau de surface saisonnièrement hauts et l'évaporation et la transpiration de l'eau souterraine à la périphérie des eaux de surface, sont les causes essentielles de la dynamique complexe et saisonnière des nappes associées aux eaux de surface. Ces processus ont été mis en évidence sur des sites de recherche dans des formations glaciaires, dunaires, littorales, fluviales et de karst couvert.
    Abstract: Resumen Los cuerpos de aguas superficiales son partes integrales de los sistemas de flujo subterráneo. El agua subterránea interactúa con la superficial en prácticamente todo tipo de paisajes, desde pequeños torrentes, lagos y humedales, hasta grandes valles fluviales y costas. Aunque se suele asumir que las áreas topográficamente elevadas son zonas de recarga de aguas subterráneas, mientras las áreas topográficamente más bajas lo son de descarga, esto es cierto básicamente para los sistemas de flujo regional. Al superponer los sistemas de flujo local, asociados a los cuerpos de agua superficial, a las condiciones regionales, resultan interacciones complejas, y esto ocurre independientemente de su posición topográfica. Los procesos hidrológicos asociados con los propios cuerpos de agua superficial, como los niveles superficiales máximos estacionales y la evapotranspiración de agua subterránea en los perímetros de cuerpos superficiales, son una de las principales causas de la complejidad y de las variaciones dinámicas de las interacciones entre aguas subterráneas y superficiales. Estos procesos se han documentado en distintas zonas investigadas, incluyendo depósitos glaciares, dunas, áreas costeras, karsts y terrazas fluviales.
    Notes: Abstract  Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical methods of operations research 49 (1999), S. 137-148 
    ISSN: 1432-5217
    Keywords: Key words: Combinatorial optimization ; complexity ; ℳ?-completeness ; scheduling ; assignment ; stack
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract. In this note, we prove ??-completeness of the following problem: Given a set of trams of different types, which are stacked on sidings in their depot and an order in which trams of specified types are supposed to leave. Is there an assignment of trams to departure times without any shunting movements? In the particular case where the number of sidings is fixed, the problem is solvable in polynomial time. We derive a dynamic program and improve its performance by a state elimination scheme. We implemented three variants of the dynamic program and applied them to random data as well as to real-world data.
    Type of Medium: Electronic Resource
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