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SENSITIVITY CONSIDERATIONS WHEN MODELING HYDROLOGIC PROCESSES WITH DIGITAL ELEVATION MODEL (2001)

Cho, Sung-Mm ; Lee, Myung Woo

Oxford, UK : Blackwell Publishing Ltd

Journal of the American Water Resources Association 37 (2001), S. 0

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ISSN: 1752-1688

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Architecture, Civil Engineering, Surveying , Geography

Notes: : The purpose of this paper is to investigate the sensitivity of a hydrologic models to the type of DEM used. This was done while modeling basin water quality with 1:24,000 and 1:250,000 U.S. Geological Survey DEMs as input to model hydrological processes. The manner in which the model results were sensitive to the choice of raster cell size (scale) is investigated in this study. The Broadhead watershed, located in New Jersey, USA, was chosen as a study area. Curve numbers were estimated by a trial and error to match simulated and observed total discharge. Monthly runoff for the watershed was used in the calibration process. Higher runoff volumes were simulated by the model when the 1:24,000 DEM were used as input data, probably due to the finer resolution which simulated increased average slope and hence higher estimated runoff from the watershed. As the simulated slope of the watershed is flatten with the 1:250,000 DEM, the response of stream flow was delayed and simulated less runoff volume. (KEY TERMS: DEM; curve number; sensitivity analysis; runoff volume; water quality; calibration.)

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1752-1688.2001.tb05523.x

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The catalytic conversion of CO2 to hydrocarbons over Fe–K supported on Al2O3–MgO mixed oxides (1998)

Kishan, Gurram ; Lee, Myung-Woo ; Nam, Sang-Sung ; [et al.]

Springer

Catalysis letters 56 (1998), S. 215-219

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ISSN: 1572-879X

Keywords: CO2 hydrogenation ; hydrocarbons ; Al2O3–MgO ; iron ; potassium ; TPR ; TPDC

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Al2O3–MgO mixed oxides prepared by a co-precipitation method have been used as supports for potassium-promoted iron catalysts for CO2 hydrogenation to hydrocarbons. The catalysts have been characterized by XRD, BET surface area, CO2 chemisorption, TPR and TPDC techniques. The CO2 conversion, the total hydrocarbon selectivity, the selectivities of C2–C4 olefins and C5+ hydrocarbons are found to increase with increase in MgO content upto 20 wt% in Fe–K/Al2O3–MgO catalysts and to decrease above this MgO content. The TPR profiles of the catalysts containing pure Al2O3 and higher (above 20 wt%) MgO content are observed to contain only two peaks, corresponding to the reduction of Fe2O3 to Fe0 through Fe3O4. However, the TPR profile of 20 wt% MgO catalyst exhibits three peaks, which indicate the formation of iron phase through FeO phase. The TPDC profiles show the formation of three types of carbide species on the catalysts during the reaction. These profiles are shifted towards high temperatures with increasing MgO content in the catalyst. The activities of the catalysts are correlated with physico-chemical characteristics of the catalysts.