518 research outputs found

    Methods and tools to evaluate the availability of renewable energy sources

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    The recent statements of both the European Union and the US Presidency pushed in the direction of using renewable forms of energy, in order to act against climate changes induced by the growing concentration of carbon dioxide in the atmosphere. In this paper, a survey regarding methods and tools presently available to determine potential and exploitable energy in the most important renewable sectors (i.e., solar, wind, wave, biomass and geothermal energy) is presented. Moreover, challenges for each renewable resource are highlighted as well as the available tools that can help in evaluating the use of a mix of different sources

    Electromagnetic Radiation

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    The application of electromagnetic radiation in modern life is one of the most developing technologies. In this timely book, the authors comprehensively treat two integrated aspects of electromagnetic radiation, theory and application. It covers a wide scope of practical topics, including medical treatment, telecommunication systems, and radiation effects. The book sections have clear presentation, some state of the art examples, which makes this book an indispensable reference book for electromagnetic radiation applications

    A Review of Current Methodologies for Regional Evapotranspiration Estimation from Remotely Sensed Data

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    An overview of the commonly applied evapotranspiration (ET) models using remotely sensed data is given to provide insight into the estimation of ET on a regional scale from satellite data. Generally, these models vary greatly in inputs, main assumptions and accuracy of results, etc. Besides the generally used remotely sensed multi-spectral data from visible to thermal infrared bands, most remotely sensed ET models, from simplified equations models to the more complex physically based two-source energy balance models, must rely to a certain degree on ground-based auxiliary measurements in order to derive the turbulent heat fluxes on a regional scale. We discuss the main inputs, assumptions, theories, advantages and drawbacks of each model. Moreover, approaches to the extrapolation of instantaneous ET to the daily values are also briefly presented. In the final part, both associated problems and future trends regarding these remotely sensed ET models were analyzed to objectively show the limitations and promising aspects of the estimation of regional ET based on remotely sensed data and ground-based measurements

    Earth Resources: A continuing bibliography with indexes, issue 10, August 1976

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    This bibliography lists 506 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1976 and June 1976. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis

    Earth resources: A continuing bibliography, issue 46

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    This bibliography lists 467 reports, articles and other documents introdcued into the NASA scientific and technical information system between April 1 and June 30, 1985. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental cultural resources geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economical analysis

    Doctor of Philosophy

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    dissertationThis dissertation examines the influence of environmental conditions and orographic barriers on the frequency, occurrence, and morphology of Great Salt Lake Effect (GSLE) precipitation. The analysis consists of the development of an updated event climatology, statistical examination of the factors necessary for events, and two case studies that employ numerical modeling to investigate orographic influences. For the climatology, events were identified using cool season (16 Sep- 15 May) WSR-88D radar imagery, radiosonde soundings, and MesoWest surface observations from 1997-98 - 2009/10. During this period, the frequency of GSLE events features considerable interannual variability that is more strongly correlated to large-scale circulation changes than lake-area variations. Events are most frequent in fall and spring, with a minimum in January when the climatological lake-surface temperature is lowest. Although forecasters commonly use a 16°C lake-700-hPa temperature difference (∆T) as a threshold for GSLE occurrence, a seasonally varying threshold based on a quadratic fit to the monthly minimum ∆T values during GSLE events is more appropriate than a single value. A probabilistic forecast method based on the difference between ∆T and this seasonally varying threshold, 850-700-hPa relative humidity, and 700-hPa wind direction offers substantial improvement over existing methods. An important consideration for forecasting because of their higher precipitation rates, banded features- with a horizontal aspect ratio of 6:1 or greater-dominate only 20% of the time the GSLE is occurring, while widespread, nonbanded precipitation is much more common. The two events examined in the second part of the study (27 Oct 2010 and 5 Nov 2011) produce synergistic interactions between lake-effect and orographic processes. A dramatic decrease in precipitation intensity and coverage occurs in numerical simulations when either the lake or terrain forcings are removed. A foehn-like flow over upstream orography reduces the relative humidity of the incipient low-level airmass and limits the intensity of both events. A convergence zone in the lee of isolated upstream topography in positioned over the north arm of the GSL, and may play a role in orgainizing the 27 Oct 2010 lake-effect band. Downstream orographic influences are large in both events, and include (1) overlake convergence due to flow stagnation along and/or blocking by the Wasatch Mountains, (2) enhancement of blocking effects due to a horizontal moisture gradient, (3) flow deflection around the Oquirrh Mountains into an orographic concavity, and (4) hydrometeor transport into high terrain. These influences are not unique to the GSL region, and our results suggest applicability to other areas where lake-effect occurs in close proximity to mountain barriers, particularly in the case of small water bodies

    Earth resources, a continuing bibliography with indexes

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    This bibliography lists 541 reports, articles and other documents introduced into the NASA scientific and technical information system. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis

    Using Spatial Data for Geo-Environmental Studies

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    The physically-based spatially-distributed model PROMET (Processes of Radiation, Mass and Energy Transfer) is applied to the Greater Damascus Basin, which is considered as one of the most important basins in Syria, to serve as a case study of using spatial data for Geo-environmental studies. Like most areas of the Middle East, the study area is characterized by large temporal and spatial variations in precipitation and by limited water resources. Due to the increasing water demand caused by the economic development and the rapid growth of population, the study area is expected to suffer from further water shortages in the future. This highlights the necessity of developing an integrated Decision Support System (DSS) to evaluate strategies for efficient and sustainable water resources management in the basin, taking into consideration global environmental changes and socio-economic conditions. The work presented here represents the first steps toward achieving this goal through applying a distributed hydrological model (an important component of any integrated DSS for water resources management) to the Greater Damascus Basin utilizing different types of spatial data used as time-dependent (e.g., meteorology) and time-independent (e.g., topography and soil) input parameters. The model PROMET, which was developed within the GLOWA-Danube project as part of the decision support system DANUBIA, is run on an hourly time step (for the period from 1991 to 2005) and a 180*180m spatial resolution to simulate the water and energy fluxes in this basin. The model is embedded within a raster-based GIS-structure which facilitates the integration of the diverse types of spatial data. The spatial information related to topography (such as elevation, slope, and exposition) as well as those related to runoff routing (such as upstream-area, channel width, and downstream proxel) are automatically extracted from Digital Elevation Model (Shuttle Radar Topography Mission, SRTM-90m DEM). The spatial patterns of the different land use/land cover classes are derived from remote sensing data (classification of a cloud-free LANDSAT 7 ETM+ image using the supervised classification algorithm). The spatial fields of meteorological input data are provided on an hourly basis through spatiotemporal interpolation of the measurements of the available weather stations. Spatial information about the soil texture is provided through generalization and aggregation of the soil type classes of the Soil Map of Syria (prepared by USAID) and transferring the soil types to texture classes. Several pedotransfer functions are then used to estimate the soil hydraulic properties for each soil texture class (and each soil layer) found in the study area. While plant physiological parameters (which are assumed to be static, such as minimum stomatal resistance) are estimated for each vegetation class using information taken from literature sources, the temporal evolution of Albedo and Leaf Area Index (LAI) are derived from five cloud-free LANDSAT-7 images acquired at different seasons of the year. The goodness of the results obtained by the model PROMET are verified and/or validated by comparing them either with their corresponding data observed in the filed or with remote sensing-derived information (e.g., snow cover). Two subcatchments are selected for the purpose of calculating the spatially-distributed annual water balances. The results indicate that the modelled mean annual runoff volume fits well with the measured discharge for both chosen subcatchment. In addition, the simulated discharge is compared to the observed one (at seven gauge stations) on a monthly basis, covering the whole simulation period (15 years). The results of the regression analysis for each of these gauge stations (with slope of regression line ranges from 0.79 to 1.04; coefficient of determination 0.69-0.90; and Nash-Sutcliffe Coefficient 0.73-0.95) indicate that there is a good correlation between simulated and observed monthly mean discharge volumes

    Earth resources: A continuing bibliography with indexes (issue 51)

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    This bibliography lists 382 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1 and September 30, 1986. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis
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