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101.
102.
In this paper we develop and compare several heuristic methods for solving the general two-dimensional cutting stock problem.
We follow the Gilmore-Gomory column generation scheme in which at each iteration a new cutting pattern is obtained as the
solution of a subproblem on one stock sheet. For solving this subproblem, in addition to classical dynamic programming, we
have developed three heuristic procedures of increasing complexity, based on GRASP and Tabu Search techniques, producing solutions
differing in quality and in time requirements. In order to obtain integer solutions from the fractional solutions of the Gilmore-Gomory
process, we compare three rounding procedures, rounding up, truncated branch and bound and the solution of a residual problem.
We have coded and tested all the combinations of algorithms and rounding procedures. The computational results obtained on
a set of randomly generated test problems show their relative efficiency and allow the potential user to choose from among
them, according to the available computing time.
Rceived: January 9, 2001 / Accepted: December 10, 2001 相似文献
103.
This paper informs about an evaluation of Spanish educational research journals using the modality of reputation inferred
from survey data. Univariate and multivariate patterns are offered. Specifically cluster analysis and non-parametric multidimensional
scaling reveal themselves as useful methods to inquire the complexity of this scientometric question which is the evaluation
of periodical series.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
104.
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Loss of residual heat removal system (RHRS) at midloop operation is one of the most significant core damage risk contributor at low power and shutdown conditions. During this kind of transients the reflux-condensation is one of the cooling mechanisms anticipated in the abnormal procedure of loss of RHRS at midloop level. In this sense, several simulations of loss of the RHRS with closed primary system with the TRACE V4.160 code have been performed considering different availability of steam generators. The present study aims to analyze the thermal-hydraulic behavior after the loss of RHRS at midloop conditions with the reflux-condensation as the only cooling mechanism available and to investigate the capability of this cooling mechanism. The simulation results show that one steam generator is sufficient to remove core decay heat of 11 MW obtaining an equilibrium pressure, but the core uncovery depends on the number of steam generators operating. Finally, an analysis of the abnormal procedure and the event trees of the loss of RHRS sequences at midloop operation has been performed taking into account the results obtained in the simulation with TRACE. 相似文献
108.
Alexander Pavlov Gonzalo D Garcia De Fernando Juan A Ordoez Lorenzo Hoz 《Journal of the science of food and agriculture》1994,64(2):141-143
The β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of unfrozen and thawed frog legs was investigated. The enzyme was extracted by either immersing frog legs in phosphate buffer 0.1 M, pH 6.0 at 25°C for 15 min or pressing them between trichinoscopy glasses. The enzyme activity was assayed using acetoacetyl-CoA as substrate and measured spectrophotometrically at 340 nm. It was possible by both extraction methods to distinguish between thawed and unfrozen samples although when the juice was obtained by pressing the HADH activity of the dilution was ~ 1.5 times higher than that obtained by immersion. The HADH activity was significantly higher (P≤0·001) in frozen-thawed frogs than in unfrozen legs because during freezing there is a release of HADH. No significative differences were found in the HADH activity in samples frozen in the temperature range -10 to -196°C. HADH activity was not affected by the storage time in crushed ice up to 6 days. 相似文献
109.
110.
Vicente Rodríguez Montequín Francisco Ortega Fernández Nicolás Abajo de Martínez Juan Antonio González Rodríguez 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(7):46-50
This research summary discusses the application of neural networks, evolutionary strategies, and other artificial intelligence
techniques in the modeling and optimization of the models used for temperature, rolling force, and torque calculation in heavy
plate milling. 相似文献