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991.
İbrahim Muter Ş. İlker BirbilKerem Bülbül Güvenç Şahin 《European Journal of Operational Research》2012
In their paper, Avella et al. (2006) investigate a time-constrained routing problem. The core of the proposed solution approach is a large-scale linear program that grows both row- and column-wise when new variables are introduced. Thus, a column-and-row generation algorithm is proposed to solve this linear program optimally, and an optimality condition is presented to terminate the column-and-row generation algorithm. We demonstrate by using Lagrangian duality that this optimality condition is incorrect and may lead to a suboptimal solution at termination. 相似文献
992.
The Pollution-Routing Problem (PRP) is a recently introduced extension of the classical Vehicle Routing Problem with Time Windows which consists of routing a number of vehicles to serve a set of customers, and determining their speed on each route segment so as to minimize a function comprising fuel, emission and driver costs. This paper presents an adaptive large neighborhood search for the PRP. Results of extensive computational experimentation confirm the efficiency of the algorithm. 相似文献
993.
994.
A new sequential quadratic programming (SQP) method for nonlinear inequality constrained optimization is proposed. The aim of this paper is to promote global convergence for SQP methods using a flexible step acceptance strategy which combines merit functions and filter techniques. Global convergence is proved under some reasonable assumptions and preliminary numerical results are reported. 相似文献
995.
An Extended Ant Colony Algorithm and Its Convergence Analysis 总被引:2,自引:0,他引:2
Giovanni?SebastianiEmail author Giovanni?Luca Torrisi 《Methodology and Computing in Applied Probability》2005,7(2):249-263
In this work, we propose a stochastic algorithm for solving
combinatorial optimization problems. The procedure is formulated within the Ant Colony Optimization (ACO) framework, and extends the so-called Graph-based Ant System with time-dependent evaporation factor, (GBAS/tdev) studied in Gutjahr (2002). In particular, we consider an ACO search procedure which also takes into account the objective function value. We provide a rigorous theoretical study on the convergence of the proposed algorithm. Further, for a toy example, we compare by simulation the rate of convergence of the proposed algorithm with those from the Random Search (RS) and from the corresponding procedure in Gutjahr (2002).AMS 2000 Subject Classification: 9OC15, 9OC27 相似文献
996.
Logic-Based Modeling and Solution of Nonlinear Discrete/Continuous Optimization Problems 总被引:2,自引:0,他引:2
This paper presents a review of advances in the mathematical programming approach to discrete/continuous optimization problems.
We first present a brief review of MILP and MINLP for the case when these problems are modeled with algebraic equations and
inequalities. Since algebraic representations have some limitations such as difficulty of formulation and numerical singularities
for the nonlinear case, we consider logic-based modeling as an alternative approach, particularly Generalized Disjunctive
Programming (GDP), which the authors have extensively investigated over the last few years. Solution strategies for GDP models
are reviewed, including the continuous relaxation of the disjunctive constraints. Also, we briefly review a hybrid model that
integrates disjunctive programming and mixed-integer programming. Finally, the global optimization of nonconvex GDP problems
is discussed through a two-level branch and bound procedure. 相似文献
997.
Hyun-Soo Ahn Rhonda Righter J. George. Shanthikumar 《Mathematical Methods of Operations Research》2005,62(3):499-514
In this paper we consider a firm that employs heterogeneous workers to meet demand for its product or service. Workers differ
in their skills, speed, and/or quality, and they randomly leave, or turn over. Each period the firm must decide how many workers
of each type to hire or fire in order to meet randomly changing demand forecasts at minimal expense. When the number of workers
of each type can by continuously varied, the operational cost is jointly convex in the number of workers of each type, hiring
and firing costs are linear, and a random fraction of workers of each type leave in each period, the optimal policy has a
simple hire- up-to/fire-down-to structure. However, under the more realistic assumption that the number of workers of each
type is discrete, the optimal policy is much more difficult to characterize, and depends on the particular notion of discrete
convexity used for the cost function. We explore several different notions of discrete convexity and their impact on structural
results for the optimal policy. 相似文献
998.
Vector Ordinal Optimization 总被引:2,自引:0,他引:2
Ordinal optimization is a tool to reduce the computational burden in simulation-based optimization problems. So far, the major effort in this field focuses on single-objective optimization. In this paper, we extend this to multiobjective optimization and develop vector ordinal optimization, which is different from the one introduced in Ref. 1. Alignment probability and ordered performance curve (OPC) are redefined for multiobjective optimization. Our results lead to quantifiable subset selection sizes in the multiobjective case, which supplies guidance in solving practical problems, as demonstrated by the examples in this paper.This paper was supported in part by Army Contract DAAD19-01-1-0610, AFOSR Contract F49620-01-1-0288, and a contract with United Technology Research Center (UTRC). The first author received additional funding from NSF of China Grants 60074012 and 60274011, Ministry of Education (China), and a Tsinghua University (Beijing, China) Fundamental Research Funding Grant, and the NCET program of China.The authors are grateful to and benefited from two rounds of reviews from three anonymous referees. 相似文献
999.
The majority of research on bilevel programming has centered on the linear version of the problem in which only one leader
and one follower are involved. This paper addresses linear bilevel multi-follower programming (BLMFP) problems in which there
is no sharing information among followers. It explores the theoretical properties of linear BLMFP, extends the Kth-best approach for solving linear BLMFP problems and gives a computational test for this approach. 相似文献
1000.
In this work we are interested in a sufficiently accurate approximation of the steady-state potentials in a Metal Semiconductor
Field Effect Transistor (MESFET), which can be obtained with the so-called depletion region approximation (see [5]). We propose
a robust method based on the shape optimization techniques to analyze and compute the depletion boundary as a function of
the applied voltage and the geometry material properties of the device. During the optimization process several intermediate
direct problems are solved using the boundary element method (BEM). To accelerate the solutions of of these systems we use
a strategy of subdividing the domain into a number of smaller subdomains [11,9]. The scheme is iterative and each subdomain
is handled by a separate node in parallel. Test runs comparing the performance of the parallel with the serial code, and other
numerical discussions are presented.
AMS subject classification 65N55, 65N38, 65K10, 78A55.
A. Nachaoui: Corresponding author. 相似文献