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Original Equation (original + equation)

Distribution by Scientific Domains

Earth and Environmental Science	50%

Selected Abstracts

Modelling variable source area dynamics in a CEAP watershed

ECOHYDROLOGY, Issue 3 2009
Helen E. Dahlke
Abstract In the Northeast US, saturation excess is the most dominant runoff process and locations of runoff source areas, typically called variable source areas (VSAs), are determined by the available soil water storage and the landscape topographic position. To predict runoff generated from VSAs some water quality models use the Soil Conservation Service Curve Number equation (SCS-CN), which assumes a constant initial abstraction of rainfall is retained by the watershed prior to the beginning of runoff. We apply a VSA interpretation of the SCS-CN runoff equation that allows the initial abstraction to vary with antecedent moisture conditions. We couple this modified SCS-CN approach with a semi-distributed water balance model to predict runoff, and distribute predictions using a soil topographic index for the Town Brook watershed in the Catskill Mountains of New York State. The accuracy of predicted VSA extents using both the original and the modified SCS-CN equation were evaluated for 14 rainfall-runoff events through a comparison with average water table depths measured at 33 locations in Town Brook from March,September 2004. The modified SCS-CN equation captured VSA dynamics more accurately than the original equation. However, during events with high antecedent rainfall VSA dynamics were still under-predicted suggesting that VSA runoff is not captured solely by knowledge of the soil water deficit. Considering the importance of correctly predicting runoff generation and pollutant source areas in the landscape, the results of this study demonstrate the feasibility of integrating VSA hydrology into water quality models to reduce non-point source pollution. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Technical note: Usability evaluation of the modified CIE1976 Uniform-Chromaticity scale for assessing image quality of visual display monitors

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 1 2003
WookGee Lee
White uniformity indicates the degree of uniform distribution of white color across the display screen and is one of the important inspection factors determining the image quality of a visual display unit (VDU). Experiments in which participants were confronted with 6 evaluation points embedded in 3 measurement groups on a VDU screen were conducted to gather the psychophysical data that include the levels of white uniformity obtained from participants and a colorimetric system (CA-100). In an accuracy test, 37.12% of the participants showed the same conclusion led by the original CIE1976 criteria, and 62.88% of the participants showed the same conclusion led by the modified equation. In magnitude estimation evaluating the display's white uniformity, the magnitude score of the modified equation (0.36) was significantly larger than that of the original equation (0.32). It was concluded that the modified equation is more sensitive to the change of white uniformity. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 85,95, 2003. [source]

A new perturbation solution for systems with strong quadratic and cubic nonlinearities

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 6 2010
Mehmet Pakdemirli
Abstract The new perturbation algorithm combining the method of multiple scales (MS) and Lindstedt,Poincare techniques is applied to an equation with quadratic and cubic nonlinearities. Approximate analytical solutions are found using the classical MS method and the new method. Both solutions are contrasted with the direct numerical solutions of the original equation. For the case of strong nonlinearities, solutions of the new method are in good agreement with the numerical results, whereas the amplitude and frequency estimations of classical MS yield high errors. For strongly nonlinear systems, exact periods match well with the new technique while there are large discrepancies between the exact and classical MS periods. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A conservative scheme for the shallow-water system on a staggered geodesic grid based on a Nambu representation

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 639 2009
Matthias Sommer
Abstract A conservative spatial discretization scheme is constructed for a shallow-water system on a geodesic grid with C-type staggering. It is derived from the original equations written in Nambu form, which is a generalization of Hamiltonian representation. The term ,conservative scheme' refers to one that preserves the constitutive quantities, here total energy and potential enstrophy. We give a proof for the non-existence of potential enstrophy sources in this semi-discretization. Furthermore, we show numerically that in comparison with traditional discretizations, such schemes can improve stability and the ability to represent conservation and spectral properties of the underlying partial differential equations. Copyright © 2009 Royal Meteorological Society [source]