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  • 1
    Electronic Resource
    Electronic Resource
    COMPARATWE EVALUATION OF FREQUENCY DISTRIBUTIONS FOR LOUISIANA EXTREME RAINFALL (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 29 (1993), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : A comparative study of five popular frequency distributions and three parameter estimation methods was conducted by using 92 Louisiana rainfall data sets. Computed results showed that the log-Pearson type 3 (LPEAR3) distribution was the most appropriate probability distribution for the Louisiana rainfall data. Furthermore, the method of moments was found to be the best estimation method for the LPEAR3 distribution based on descriptive performance indices. A first-order error analysis was performed on the parameters of the LPEAR3 distribution. Computed results showed that the predicted quantiles of the LPEAR3 distribution were most sensitive to the population mean and relatively insensitive to the coefficient of the skewness of the distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1993.tb03202.x
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  • 2
    Electronic Resource
    Electronic Resource
    Phosphor currents in ZnS:Mn ac thin film electroluminescent display devices (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4148-4155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conduction current in the phosphor layer of ZnS:Mn ac thin film electroluminescent (ACTFEL) display device was measured as a function of the amplitude and the rise time of the bipolar voltage pulses: electric field in the phosphor was also determined. It was found that the clamping field of an ac thin film electroluminescent device is not a single-valued device characteristic. The clamping field depended upon the rise time of the applied voltage pulse increasing in value as the rise time became smaller. These data were interpreted in terms of a nonideal breakdown of the insulator-phosphor interface and a time delay involved in the emission of electrons from this interface. To account for the nonideality in the interface breakdown the ac equivalent circuit of the ACTFEL device was modified by including a voltage-dependent resistor in parallel with the phosphor capacitance. The phosphor current measurements, transferred charge measurements and tunneling current calculations indicate that in the nonhysteretic ZnS:Mn devices under investigation, impact ionization in the phosphor layer, if present at all, leads to relatively small carrier multiplication factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352223
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  • 3
    Electronic Resource
    Electronic Resource
    Electric field and conduction current in ac thin-film electroluminescent display devices (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1811-1819 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Current flow through the phosphor layer of ac thin film electroluminescent display devices has been analyzed. It is shown that the traditional capacitive bridge technique for measuring the time dependence of phosphor conduction current [iLP(t)] can yield inaccurate results, especially when the multiplication factor of [(CI + Cp)/CI] is not used, and the phosphor layer has bulk space charge; CI and Cp are insulator and phosphor layer capacitances, respectively. A new method for the measurement of iLP(t) has been developed. It is more accurate and is applicable even when the bulk charge in the phosphor layer is not negligible. The new method was applied to the study of ZnS:Mn ac thin-film electroluminescent (ACTFEL) devices excited by voltage pulses of three different slew rates. iLP(t) measured by the new method was compared against the bridge current (ibridge). Electric field and displacement current in the phosphor were calculated. Transferred charge computed by integrating iLP and ibridge over half cycle was compared against the polarization charge obtained from the Q–V curve of the device.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349497
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  • 4
    Electronic Resource
    Electronic Resource
    Sampling variance of a T-year flood estimated by curve-fitting (1994)
    Springer
    Stochastic environmental research and risk assessment 8 (1994), S. 233-258 
    Details
    ISSN: 1436-3259
    Keywords: Flood ; China ; river ; sampling variance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The sampling variance of a T-year flood when estimated using a curve-fitting method results from the errors in hydrologic observations, plotting positions, and model-fitting. This paper develops a method to quantify the contribution of plotting positions to the sampling variance of the T-year flood magnitude. Application of the method to 150 flood-flow data sets of 41 rivers in the People's Republic of China show that the errors due to plotting positions contribute more to the sampling variance than others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01587237
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  • 5
    Electronic Resource
    Electronic Resource
    MMO: An improved estimator for log-Pearson type-3 distribution (1994)
    Springer
    Stochastic environmental research and risk assessment 8 (1994), S. 219-231 
    Details
    ISSN: 1436-3259
    Keywords: Parameter estimation ; flood frequency analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A mixed method combining the method of moments and the method of optimization (MMO) was developed for estimating the parameters of the log-Pearson type 3 (LP3) distribution. The MMO estimates the parameters of mean and standard deviation by the method of indirect moments (MIM) and estimates the coefficient of skewness by minimizing both the relative root average square error (RRASE) and the relative average bias (RAB). Both the predictive capability and descriptive capability of six popular estimation methods were evaluated using 90 sets of observed flood data and six selected LP3 populations with 1000 samples for each selected sample size. The performance of the MMO was compared with those of five other selected estimation methods. A weighted ranking index (WRI) procedure was developed to help select the best combination of distribution and method for the Louisiana flood data. The WRI takes both the predictive capability and the descriptive capability into account in the evaluation. The combination of LP3/MMO was found to be the best combination for Louisiana flood data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01587236
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  • 6
    Electronic Resource
    Electronic Resource
    Modeling and error analysis of kinematic-wave equations of furrow irrigation (1994)
    Springer
    Irrigation science 15 (1994), S. 113-121 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A moving control volume approach was used to model the advance phase of a furrow irrigation system whereas a fixed control volume was used to model the nearly stationary phase and the runoff rate. The resulting finite-difference equations of the kinematic-wave model were linearized and explicit algebraic expressions were obtained for computation of advance and runoff rate. The solutions for the advance increment and the runoff rate were compared with the nonlinear scheme, the zero-inertia model, and a set of field data. A close agreement was found between the models and the field data. Assuming a constant infiltration rate, a differential equation was derived to estimate the error between the kinematic-wave model and the zero-inertia model in predicting the flow cross-sectional area along the field length. The differential equation and two dimensionless terms were used to define the limits for use of the kinematic-wave model in furrow irrigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187197
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  • 7
    Electronic Resource
    Electronic Resource
    Simulation of leachate migration in leaky aquifers (1994)
    Springer
    Water resources management 8 (1994), S. 265-284 
    Details
    ISSN: 1573-1650
    Keywords: Groundwater ; pollution ; finite difference method ; dispersion ; density dependent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A two-dimensional cross-section finite difference model is presented to simulate density dependent leachate migration in leaky aquifers. Unlike existing models, a new approach is adopted to couple the groundwater-flow equation and the hydrodynamic dispersion equation with the elimination of the intermediate step of calculating velocities. The concept of the reference density is employed, permitting increased accuracy (over pressure-based models) in the representation of the transport process. The model is then used to study the effect of several hydraulic and transport parameters on the flow pattern and plume migration which are found to be very sensitive to most of these parameters. Equiconcentration and equipotential lines are overlapped to provide a better understanding of the coupling effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872401
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  • 8
    Electronic Resource
    Electronic Resource
    A note on saltwater intrusion in coastal aquifers (1990)
    Springer
    Water resources management 4 (1990), S. 123-134 
    Details
    ISSN: 1573-1650
    Keywords: Coastal aquifers ; cyclic flow ; dispersion ; finite element method ; Galerkin's method ; molecular diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Description / Table of Contents: Resumé Pendant les dernières quelques années, le transport des contaminants dans les aquifères a reçu une attention considerable. Aux aquifères de la côte, il existe des zones où l'eau salé et l'eau douce se dispersent quand le flux de l'eau et le transport des ions du sel s'unissent. Le patron de flux [flow pattern] des fluides miscibles qui ont des différents unités de poids est characterisé par le flux cyclique au bord de la côte la largeur de la region de dispersion est considerable, et les suppositions de ‘'interface tranchante’ [sharp interface] peut conduire a des faux résultats. Pour mieux comprendre le phénomène de l'instrusion de l'eau salé, le modèle des ‘éléments limités’ [finite element] a été appliqué dans deux problèmes dejà publiés. L'effet de l'abaissement piezométrique à cause du pompage excessif a été étudiés. Les paramètres physique ont été extraits des cas dejà étudiés, conduits par Rouven-Stoessinger et Kawatani, et la comparaisons avec leurs résultats a été fait.
    Notes: Abstract Transport of contaminants in aquifers has received considerable attention over the past few years. In coastal aquifers, a dispersion zone between saline water and fresh water exists where the flow of water and transport of salt ions are coupled. The flow pattern of two miscible fluids of different unit weights is characterized by the cyclic flow at the shore boundary. The width of the dispersion zone may be considerable, with the sharp interface assumption leading to erroneous results. A finite element model was applied to two prepublished problems for purposes of obtaining a better understanding of the saline water intrusion phenomenon. The effect of lowering the piezometric head due to excessive pumping was investigated. Physical parameters were extracted from the studies conducted by Kawatani and Rouve and Stoessinger, and comparison with their results was made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429801
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  • 9
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    Characterization of thin film CdS-CdTe solar cells (1991)
    Elsevier
    Details
    Publication Date: 1991-02-01
    Print ISSN: 0379-6787
    Electronic ISSN: 1878-2655
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Elsevier
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  • 10
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    Sampling variance of a T-year flood estimated by curve-fitting (1994)
    Springer
    Details
    Publication Date: 1994-09-01
    Print ISSN: 1436-3240
    Electronic ISSN: 1436-3259
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Published by Springer
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