Engineering Literature (engineering + literature)

Distribution by Scientific Domains


Selected Abstracts


An adaptive penalty scheme for genetic algorithms in structural optimization

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2004
Afonso C. C. Lemonge
Abstract A parameter-less adaptive penalty scheme for genetic algorithms applied to constrained optimization problems is proposed. Using feedback from the evolutionary process the procedure automatically defines a penalty parameter for each constraint. The user is thus relieved from the burden of having to determine sensitive parameter(s) when dealing with every new constrained optimization problem. The procedure is shown to be effective and robust when applied to test problems from the evolutionary computation literature as well as several optimization problems from the structural engineering literature. Copyright © 2003 John Wiley & Sons, Ltd. [source]


A new model for gas flow in pipe networks

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 7 2010
M. Herty
Abstract We introduce a new model for gas dynamics in pipe networks by asymptotic analysis. The model is derived from the isothermal Euler equations. We present the derivation of the model as well as numerical results illustrating the validity and its properties. We compare the new model with existing models from the mathematical and engineering literature. We further give numerical results on a sample network. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Robust sequential designs for nonlinear regression

THE CANADIAN JOURNAL OF STATISTICS, Issue 4 2002
Sanjoy Sinha
Abstract The authors introduce the formal notion of an approximately specified nonlinear regression model and investigate sequential design methodologies when the fitted model is possibly of an incorrect parametric form. They present small-sample simulation studies which indicate that their new designs can be very successful, relative to some common competitors, in reducing mean squared error due to model misspecifi-cation and to heteroscedastic variation. Their simulations also suggest that standard normal-theory inference procedures remain approximately valid under the sequential sampling schemes. The methods are illustrated both by simulation and in an example using data from an experiment described in the chemical engineering literature. Les auteurs définissent formellement le concept de modéle de régression non linéaire approxima-tif et proposentdes plans d'expérience séquentiels pour les situations o4uG la forme paramétrique du modéle ajusté est inexacte. Ils présentent une étude de simulation qui montre que, pour de petits échantillons, leurs nouveaux plans sont largement préférables aux plans usuels en terme de réduction de I'erreur quadratique moyenne associée à rinadéquation du modéle et à l'hétéroscédasticité. Leurs simulations montrent aussi que les procédures d'inférence classiques associées au paradigme normal restent valables, à peu de choses prés, pour ces plans expéimentaux se'quentiels. La methodologie proposde est illustrée par voie de simulation et au moyen d'une application concréte tirée de la pratique du génie chimique. [source]


INCENTIVE REGULATION AND THE ROLE OF CONVEXITY IN BENCHMARKING ELECTRICITY DISTRIBUTION: ECONOMISTS VERSUS ENGINEERS

ANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 2 2008
Emili GRIFELL-TATJÉ
ABSTRACT,:,This note illustrates the potential impact of the specification of a convex production technology on establishing minimal costs compared to the use of a non-convex technology when benchmarking electricity distributors. This methodological reflection is mainly motivated by recent engineering literature providing evidence for non-convexities in electricity distribution. An empirical illustration using non-parametric specifications of technology illustrates this main point using a sample of Spanish electricity distribution firms earlier analysed in Grifell-Tatjé and Lovell (2003). [source]