Stochastic transportation problems attract much attention in many fields, such as resource allocation, production management, etc. In this paper, after analyzing how to process random constraints in chanceconstrained...
详细信息
ISBN:
(纸本)9781424437092
Stochastic transportation problems attract much attention in many fields, such as resource allocation, production management, etc. In this paper, after analyzing how to process random constraints in chanceconstrainedprogramming, propose a quasi-linear pattern based on expectation and variance, moreover, give the quasi-linear programming model of stochastic transportation problems with good operability, finally, the performance of this model is discussed through an example. All these indicate the quasi-linear programming model can solve the stochastic transportation problems briefly and effectively, so it enriches methods of stochastic transportation problems.
In this paper, we consider a class of two-stage stochastic optimization problems arising in the protection of vital arcs in a critical path network. A project is completed after a series of dependent tasks are all fin...
详细信息
In this paper, we consider a class of two-stage stochastic optimization problems arising in the protection of vital arcs in a critical path network. A project is completed after a series of dependent tasks are all finished. We analyze a problem in which task finishing times are uncertain but can be insured a priori to mitigate potential delays. A decision maker must trade off costs incurred in insuring arcs with expected penalties associated with late project completion times, where lateness penalties are assumed to be lower semicontinuous nondecreasing functions of completion time. We provide decomposition strategies to solve this problem with respect to either convex or nonconvex penalty functions. In particular, for the nonconvex penalty case, we employ the reformulation-linearization technique to make the problem amenable to solution via Benders decomposition. We also consider a chance-constrained version of this problem, in which the probability of completing a project on time is sufficiently large. We demonstrate the computational efficacy of our approach by testing a set of size- and-complexity diversified problems, using the sample average approximation method to guide our scenario generation.
Classical optimal reactive power dispatch (ORPD) is usually formulated as a deterministic optimization problem, such that the network structure and load power injections are known and fixed. Hence, the influences of l...
详细信息
Classical optimal reactive power dispatch (ORPD) is usually formulated as a deterministic optimization problem, such that the network structure and load power injections are known and fixed. Hence, the influences of load uncertainties and branch outages are not typically considered. This paper proposes a chance-constrained programming formulation for ORPD that considers uncertain nodal power injections and random branch outages. A solution method combining both probabilistic load flow and a genetic algorithm is proposed and demonstrated in order to solve the problem. Simulations on several test systems show that the proposed method can prevent under-compensation or over-compensation of reactive power and increase voltage security margins. These advantages are achieved with the acceptable expense of a small increase in active power loss when compared with the results of classical deterministic ORPD. Several techniques are presented in order to improve the efficiency of the proposed method and case studies demonstrate the effectiveness of the techniques. (C) 2009 Elsevier Ltd. All rights reserved.
The aim of this paper is to provide new efficient methods for solving general chance-constrained integer linear programs to optimality. Valid linear inequalities are given for these problems. They are proved to charac...
详细信息
The aim of this paper is to provide new efficient methods for solving general chance-constrained integer linear programs to optimality. Valid linear inequalities are given for these problems. They are proved to characterize properly the set of solutions. They are based on a specific scenario, whose definition impacts strongly on the quality of the linear relaxation built. A branch-and-cut algorithm is described to solve chance-constrained combinatorial problems to optimality. Numerical tests validate the theoretical analysis and illustrate the practical efficiency of the proposed approach.
In this study, a two-level scheme with robust dynamic real-time optimization and distributed model predictive control (DMPC) is presented for plant-wide processes. On the top layer, chance-constrained programming (CCP...
详细信息
ISBN:
(纸本)9781424467129
In this study, a two-level scheme with robust dynamic real-time optimization and distributed model predictive control (DMPC) is presented for plant-wide processes. On the top layer, chance-constrained programming (CCP) is employed in the real-time optimization with economic and model uncertainties, in which the constraints containing stochastic parameters are guaranteed to be satisfied at a high level of probability. On the lower layer, the on-line optimization of the whole system is decomposed into that of several small cooperative subsystems in distributed structures. The walking beam reheating furnace optimization and control problems are illustrated to verify the effectiveness and practicality of the proposed scheme.
The time-cost trade-off problem studies how to modify project activities to achieve the trade-off between the completion time and the total project *** real world,the trade-off between the total project cost and the c...
详细信息
The time-cost trade-off problem studies how to modify project activities to achieve the trade-off between the completion time and the total project *** real world,the trade-off between the total project cost and the completion time,and the uncertainty of the external environment are both considerable for *** this paper,a new fuzzy random time-cost trade-off model is proposed,in which the philosophy of chance-constrained programming is introduced as decision-making *** approach by integrating fuzzy random simulation and genetic algorithm is produced to search the quasi-optimal *** the whole,this paper is to illustrate the process of achieving the optimal balance of the completion time and the project total cost in mixed uncertain environment with randomness and fuzziness.
In this study, a random-boundary-interval linear programming (RBILP) method is developed and applied to the planning of municipal solid waste (MSW) management under dual uncertainties. In the RBILP model, uncertain in...
详细信息
In this study, a random-boundary-interval linear programming (RBILP) method is developed and applied to the planning of municipal solid waste (MSW) management under dual uncertainties. In the RBILP model, uncertain inputs presented as interval numbers can be directly communicated into the optimization process;besides, intervals with uncertain lower and upper bounds can be handled through introducing the concept of random boundary interval. Consequently, robustness of the optimization process can be enhanced. To handle uncertainties with such complex presentations, an integrated chance-constrained programming and interval-parameter linear programming approach (ICCP) is proposed. ICCP can help analyze the reliability of satisfying (or risk of violating) system constraints under uncertainty. The applicability of the proposed RBILP and ICCP approach is validated through a case study of MSW management. Violations for capacity constraints are allowed under a range of significant levels. Interval solutions associated with different risk levels of constraint violation are obtained. They can be used for generating decision alternatives and thus helping waste managers to identify desired policies under various environmental, economic, and system-reliability constraints.
In real-life projects, both the trade-off between the project cost and the project completion time, and the uncertainty of the environment are considerable aspects for decision-makers. However, the research on the tim...
详细信息
In real-life projects, both the trade-off between the project cost and the project completion time, and the uncertainty of the environment are considerable aspects for decision-makers. However, the research on the time-cost trade-off problem seldom concerns stochastic environments. Besides, optimizing the expected value of the objective is the exclusive decision-making criterion in the existing models for the stochastic time-cost trade-off problem. In this paper, two newly developed alternative stochastic time-cost trade-off models are proposed, in which the philosophies of chance-constrained programming and dependent-chanceprogramming are adopted for decision-making. In addition, a hybrid intelligent algorithm integrating stochastic simulations and genetic algorithm is designed to search the quasi-optimal schedules under different decision-making criteria. The goal of the paper is to reveal how to obtain the optimal balance of the project completion time and the project cost in stochastic environments. (C) 2009 Elsevier Inc. All rights reserved.
This paper considers product mix problems including randomness of future returns, ambiguity of coefficients and flexibility of upper value with respect to each constraint such as budget, human resource, time and sever...
详细信息
This paper considers product mix problems including randomness of future returns, ambiguity of coefficients and flexibility of upper value with respect to each constraint such as budget, human resource, time and several costs. Particularly, the flexibility is assumed to be a fuzzy goal. Then, several models based on maximizing total future profits under a level of satisfaction to each fuzzy goal are proposed. Furthermore, the model considering preference ranking to each fuzzy goal of constraints is proposed. Since these problems are basically formulated as nonlinear programming problems, the transformations into deterministic equivalent problems are introduced and the efficient solution methods are developed. A numerical example for product mix problem is given to illustrate our proposed models. (C) 2008 Elsevier Ltd. All rights reserved.
Reliability-based design optimization is concerned with designing a product to optimize an objective function, given uncertainties about whether various design constraints will be satisfied. However, the widespread pr...
详细信息
Reliability-based design optimization is concerned with designing a product to optimize an objective function, given uncertainties about whether various design constraints will be satisfied. However, the widespread practice of formulating such problems as chance-constrained programs can lead to misleading solutions. While a decision-analytic approach would avoid this undesirable result, many engineers find it difficult to determine the utility functions required for a traditional decision analysis. This paper presents an alternative decision-analytic formulation that, although implicitly using utility functions, is more closely related to probability maximization formulations with which engineers are comfortable and skilled. This result combines the rigor of decision analysis with the convenience of existing optimization approaches.
暂无评论