Begell House Inc.
Hybrid Methods in Engineering
HME
1099-2391
1
1
1999
A CLOSED-FORM SOLUTION TO THE ONE-DIMENSIONAL LINEAR AND NONLINEAR RADIATIVE TRANSFER PROBLEM
18
Marco T.
Vilhena
Departamento de Engenharia Mecânica, Instituto de Matematica Aplicada, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
L. B.
Barichello
Instituto de Matematica, Universidade Federal do Rio Grande do Sul, 91509-900 Porto Alegre, RS, Brazil
The LTSN method, combined with the decomposition method, is used to develop a closed-form solution to one-dimensional linear and nonlinear discrete ordinates radiative transfer problems. The extension of this procedure to all one-dimensional approximations of the transport equations, displayed as a set of first-order linear differential equations, is also presented. Our attention is focused on the topics of derivation and review of some applications of the discussed method.
POWER PLANT DISCHARGES OF TOTAL RESIDUAL CHLORINE AND TRIHALOMETHANES INTO RIVERS: POTENTIAL FOR HUMAN HEALTH AND ECOLOGICAL RISKS
18
Christine S.
Lew
Applied Research and Development Division, Tetra Tech, Inc., Lafayette, California, USA 94549
William B.
Mills
Applied Research and Development Division, Tetra Tech, Inc., 3746 Mt. Diablo Blvd., #300, Lafayette, California 94549, USA 94549
John Y.
Loh
Applied Research and Development Division, Tetra Tech, Inc., Lafayette, California, USA 94549
A model was developed and applied to predict the fate of total residual chlorine, free residual chlorine, and chloramines in rivers from time-variable releases from power plant discharges of these constituents. The model also predicts the formation of trihalomethanes in the presence of the residual chlorine. The stoichiometric yield and formation rate of each trihalomethane are estimated using data from prior studies. Carcinogenic human health risks are predicted from exposure to trihalomethanes; an ecological risk screening, using the hazard quotient approach, is used to evaluate total residual chlorine impacts. To illustrate the model's capabilities and limitations, the model is applied to a power plant discharge scenario: predicted total residual chlorine levels, expressed in terms of a hazard quotient for the protection of aquatic organisms, exceed the U.S. Environmental Protection Agency's (EPA's) criteria for locations less than 5 km downstream of the discharge; excess lifetime risk from exposure to four trihalomethanes is just below 10−6, which is a typical level of concern.
DESIGN OF OPTIMUM EXPERIMENTS FOR THE ESTIMATION OF THE THERMAL CONDUCTIVITY COMPONENTS OF ORTHOTROPIC SOLIDS
18
M. M.
Mejias
Department of Mechanical Engineering, EE/COPPE, Federal University of Rio de Janeiro, UFRJ Cid. Universitaria, Cx. Postal: 68503 Rio de Janeiro, RJ, 21945-970 Brazil
M. N.
Ozisik
Mechanical and Aerospace Engineering Department North Carolina State University, Raleigh, N. C. 27607
Helcio R. B.
Orlande
Department of Mechanical Engineering, Federal University of Rio de Janeiro – POLI/COPPE,
Centro de Tecnologia, Caixa Postal: 68503, Cidade Universitária, Rio de Janeiro, 21941-972, Brazil
In this article we apply the D-optimum criterion to determine experimental variables, such as the number and locations of sensors, heating time, and duration of the experiment, for the estimation of the three thermal conductivity components of an orthotropic solid. The Levenberg-Marquardt method is applied for solving the present parameter estimation problem, by using simulated experimental data. Highly accurate estimates are obtained here with such a method for three different test cases. We also show that the accuracy of the estimated parameters deteriorates as experimental variables other than those chosen optimally are used in the analysis.
THERMAL INTERACTION BETWEEN FREE CONVECTION AND FORCED CONVECTION ALONG A CONDUCTING PLATE EMBEDDED IN A POROUS MEDIUM
12
J.-J.
Shu
Department of Pharmacy, National University of Singapore, Singapore
Ioan
Pop
Department of Applied Mathematics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
The article investigates the conjugate problem of free convection and forced convection along a conducting vertical plate separating two semi-infinite porous reservoirs maintained at different temperatures. The mean heat flux through the plate and the wall temperature distribution on the both sides of the plate are determined. The results show the effects of the resistance parameter Rt and free-to-forced-convection parameter Rt* on the mean heat transfer through the plate and on the wall temperatures of the both sides of the plate.
INTEGRAL TRANSFORM SOLUTION OF THE RADIOACTIVE TRACER EQUATION FOR A FIVE-SPOT PATTERN
12
Alcino Resende
Almeida
Petrobras Research Center, DIPLOT/SEPROT, Ilha do Fundao Quadra 7, Rio de Janeiro, Brazil
The generalized integral transform technique (GITT) is employed to solve analytically the two-dimensional tracer equation for the radioactive case, i.e., a very small amount of a decaying tracer released at the injection wells (impulsive input). A five-spot pattern and classic assumptions of steady-state single-phase flow and unit mobility ratio are adopted. The solution is compared against asymptotic analytical solutions from other sources, and benchmark results are presented. Additionally, some results that are not given explicitly in the literature are presented.
SHAPE FUNCTIONS GENERATION WITH Mathematica
8
Mikhail D.
Mikhailov
Applied Mathematics Center, PO Box 384, Sofia, Technical University, Sofia, Bulgaria; and Mechanical Engineering Department—EE/COPPE/UFRJ, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CP 68.503, Rio de Janeiro, RJ, 21945-970, Brasil
Mathematica rules that produce explicit closed-form formulas for a large class of shape functions are presented. Since the results differ from the ones recently published by Dydo and Busby in Communications in Numerical Methods in Engineering, the Mathematica implementation of their algorithm is also given to show that both approaches lead to the same results. Examples are solved for 1D, 2D, and 3D elements. Mathematica, using the rules presented, obtains the desired shape functions directly in C or FORTRAN form.