作者:
Wei ZhaoHao ChenDevrim Murat YazanHadi TaghavifarYucheng LyuAldis BulisIEBIS
Department of High-tech Business and Entrepreneurship Faculty of Behavioural Management and Social Sciences University of Twente the Netherlands Faculty of Business Administration
Turiba University Latvia. IEBIS
Department of High-tech Business and Entrepreneurship Faculty of Behavioural Management and Social Sciences University of Twente the Netherlands. Electronic address: h.chen-3@utwente.nl. IEBIS
Department of High-tech Business and Entrepreneurship Faculty of Behavioural Management and Social Sciences University of Twente the Netherlands. Department of Technology and Safety (ITS)
UiT-The Arctic University of Norway Tromso Norway.
Effective management of energy and water resources is essential for mitigating environmental impacts and enhancing sustainability. This paper proposes a multiple-objective linear program tailored to accommodate energy...
详细信息
Effective management of energy and water resources is essential for mitigating environmental impacts and enhancing sustainability. This paper proposes a multiple-objective linear program tailored to accommodate energy-water applications in diverse climatic conditions in the Netherlands. It introduces an innovative approach that combines few-shot learning, designed to expand the datasets effectively, and sophisticated machine learning architectures such as Deep Autoregression to allow for more precise and reliable predictions. The method implements machine learning to enhance multi-objective operations research optimisation problems and significantly reduces the reliance on extensive datasets typically necessary for accurate predictive modelling. Experimental results show a notable increase in prediction accuracy, with the integrated approach surpassing traditional models by up to about 33 %. Additionally, we achieve an extension of the 8 solved scenarios to 800 similar scenarios so that the operational efficiency and sustainability of resource management are significantly improved, demonstrating the potential of machine learning technologies in this field. The strategic application of the proposed method compensates for the limitations associated with small datasets and ensures the scalability and effectiveness of the predictive models across various environmental scenarios.
In surface mining operations, fleet management systems seek to make optimal decisions to handle material in two steps: path production optimization and real-time truck dispatching. This paper develops a multiple objec...
详细信息
In surface mining operations, fleet management systems seek to make optimal decisions to handle material in two steps: path production optimization and real-time truck dispatching. This paper develops a multipleobjective transportation model for real-time truck dispatching. The model addresses two major drawbacks of former models. The proposed model dispatches the trucks to destinations trying to simultaneously minimize shovel idle times, truck wait times, and deviations from the path production requirements established by the production optimization stage. To evaluate the performance of the proposed model, we developed a benchmark model based on the backbone of the most widely used fleet management system in the mining industry (Modular Mining DISPATCH). Afterward, we built a discrete event simulation model of the truck and shovel operation using an iron ore mine case study, implemented both of the dispatching models, and compared the results. The implementation of the models suggests that the multipleobjective model developed in this paper is able to meet the production requirements of the operation using a fleet at 85% of the size of the deterministically calculated desired fleet. In addition, the model is able to meet the full capacity of the processing plants with a fleet of 30% less trucks than the desired fleet. (C) 2019 Elsevier B.V. All rights reserved.
The cutting-plane optimization methods rely on the idea that any subgradient of the objective function or the active/violated constraints defines a halfspace to be excluded from a set that contains an optimal solution...
详细信息
The cutting-plane optimization methods rely on the idea that any subgradient of the objective function or the active/violated constraints defines a halfspace to be excluded from a set that contains an optimal solution: the localizing set. This algorithm converges towards a global minimum of any pseudoconvex subdifferentiable function. A naive extension for multiobjective optimization would be using simultaneously some subgradients of all objective functions for a given feasible point. However, as demonstrated in this paper, this approach can lead to a convergence towards non-optimal points. This paper introduces an optimization strategy for cutting-plane methods to cope with multiobjective problems without any scalarization procedure. The proposed strategy guarantees that its optimal solution is a Pareto Optimal solution of the original problem, which is also no worse than the starting point, and that any Pareto Optimal solution can be sampled. Moreover, the auxiliary problem is infeasible only if the original problem is also infeasible. The new strategy inherits the original theoretical guarantees of cutting planes methods and it can be applied to build other strategies. (C) 2019 Elsevier B.V. All rights reserved.
This paper extends the use of Zoutendijk method for constrained multiobjective optimization problems. This extension is a nonparametric direction-based algorithm. More precisely, considering all objective functions an...
详细信息
This paper extends the use of Zoutendijk method for constrained multiobjective optimization problems. This extension is a nonparametric direction-based algorithm. More precisely, considering all objective functions and binding constraints, this algorithm proposes a convex quadratic subproblem for generating a convenient improving feasible direction. Then, by using some elementary computation, the step length corresponding to the current direction is obtained. Some useful theoretical results corresponding to the proposed method are demonstrated. Using some of these theoretical results and under some mild conditions, the convergence of the proposed method is proved. The Zoutendijk multiobjective optimization (ZMO) method is not a population-based method. However, in order to find an approximation of the nondominated frontier, we need to have an appropriate population of initial feasible solutions. To achieve this aim, in this paper a cutting plane-like procedure which can generate an appropriate population of feasible solutions over the feasible set is proposed. Finally, in order to show its superiority, the proposed method is implemented for some well-known test problems. By employing some performance assessment criteria, the obtained numerical results are compared with the NSGA II method for all test problems. To have a more convenient comparison, the results are depicted in some performance profiles. Moreover, the obtained nondominated frontiers of these methods are compared for some test problems. The numerical results confirm the high performance of the ZMO method. (C) 2018 Elsevier B.V. All rights reserved.
We introduce a new interactive multiobjective optimization method operating in the objective space called Nonconvex Pareto Navigator. It extends the Pareto Navigator method for nonconvex problems. An approximation of ...
详细信息
We introduce a new interactive multiobjective optimization method operating in the objective space called Nonconvex Pareto Navigator. It extends the Pareto Navigator method for nonconvex problems. An approximation of the Pareto optimal front in the objective space is first generated with the PAINT method using a relatively small set of Pareto optimal outcomes that is assumed to be given or computed prior to the interaction with the decision maker. The decision maker can then navigate on the approximation and direct the search for interesting regions in the objective space. In this way, the decision maker can conveniently learn about the interdependencies between the conflicting objectives and possibly adjust one's preferences. To facilitate the navigation, we introduce special cones that enable extrapolation beyond the given Pareto optimal outcomes. Besides handling nonconvexity, the new method contains new options for directing the navigation that have been inspired by the classification-based interactive NIMBUS method. The Nonconvex Pareto Navigator method is especially well-suited for computationally expensive problems, because the navigation on the approximation is computationally inexpensive. We demonstrate the method with an example. Besides proposing the new method, we characterize interactive navigation based methods in general and discuss desirable properties of navigation methods overall and in particular with respect to Nonconvex Pareto Navigator. (C) 2018 Elsevier B.V. All rights reserved.
At universities, the timetable plays a large role in the daily life of students and staff, showing when and where lectures are given. But whenever a schedule is executed in a dynamic environment, disruptions will occu...
详细信息
At universities, the timetable plays a large role in the daily life of students and staff, showing when and where lectures are given. But whenever a schedule is executed in a dynamic environment, disruptions will occur. It is then desirable to find a new timetable similar to the old one, so only a few people will be affected. This leads to a minimum perturbation problem, where the goal is to find a feasible timetable by changing as few assignments as possible. This solution will, however, often lead to timetables of low quality as it can have many undesired features that will cause much inconvenience for effected parties. In this paper we show that minimum perturbation solutions often have low quality and how using additional perturbations results in timetables with significantly higher quality while still keeping the number of perturbations low, so the solutions can be practically implemented. We formulate a bi-objective model and propose a method to solve it by using mixed integer programming. We test the method on standard instances of the Curriculum-based Course Timetabling Problem with four different types of disruptions. The use of bi-objective optimization enables us to generate multiple solutions whereby we provide the decision makers with multiple choices for handling the disruption. This allows the decision makers to determine the best trade-off between the number of perturbations and the quality, ultimately leading to better timetables for students and staff when disruptions occur. (C) 2019 Elsevier B.V. All rights reserved.
Several robustness concepts for multi-objective uncertain optimization have been developed during the last years, but not many solution methods. In this paper we introduce two methods to find min-max robust efficient ...
详细信息
Several robustness concepts for multi-objective uncertain optimization have been developed during the last years, but not many solution methods. In this paper we introduce two methods to find min-max robust efficient solutions based on scalarizations: the min-ordering and the max-ordering method. We show that all point-based min-max robust weakly efficient solutions can be found with the max-ordering method and that the min-ordering method finds set-based min-max robust weakly efficient solutions, some of which cannot be found with formerly developed scalarization based methods. We then show how the scalarized problems may be approached for multi-objective uncertain combinatorial optimization problems with special uncertainty sets. We develop compact mixed-integer linear programming formulations for multi-objective extensions of bounded uncertainty (also known as budgeted or Gamma-uncertainty). For interval uncertainty, we show that the resulting problems reduce to well-known single-objective problems. (C) 2018 The Authors. Published by Elsevier B.V.
Decision making in the presence of uncertainty and multiple conflicting objectives is a real-life issue in many areas of human activity. To address this type of problem, we study highly robust (weakly) efficient solut...
详细信息
Decision making in the presence of uncertainty and multiple conflicting objectives is a real-life issue in many areas of human activity. To address this type of problem, we study highly robust (weakly) efficient solutions to uncertain multiobjective linear programs (UMOLPs) with objective-wise uncertainty in the objective function coefficients. We develop properties of the highly robust efficient set, characterize highly robust (weakly) efficient solutions using the cone of improving directions associated with the UMOLP, derive several upper and lower bound sets on the highly robust (weakly) efficient set, and present a robust counterpart for a class of UMOLPs. As various results rely on the acuteness of the cone of improving directions, we also propose methods to verify this property. (C) 2018 Elsevier B.V. All rights reserved.
This paper presents a biobjectivemultiple allocation p-hub median problem, discusses the properties of the Pareto frontier and proposes exact and heuristic algorithms for finding the Pareto frontier. Our motivation e...
详细信息
This paper presents a biobjectivemultiple allocation p-hub median problem, discusses the properties of the Pareto frontier and proposes exact and heuristic algorithms for finding the Pareto frontier. Our motivation emanates from airline networks and their new hub investment strategies. The first objective minimizes the total transportation cost of the network, while the second one minimizes 2-stop journeys in order to improve customer satisfaction, which is negatively affected by the multiple-transit routes of airlines. Although using hubs reduces operating costs in networks, a cost-effective hub network may not imply minimum individual travel times for passengers, or happy passengers. It is well-known that airline customers prefer flights with fewer stops. However, reducing 2-stop routes increases the number of arcs, non-stop and 1-stop routes, and thus the total cost in the network. We analyzed the tradeoff between these objective functions. We performed experiments on well-Known data sets from the literature. We were able to find the Pareto frontier exactly for small/medium size instances. A variable neighborhood search (VNS) heuristic is presented to approximate the Pareto frontier of large size instances. We also performed an application on the current Turkish aeronautics network. The results are presented and discussed. (C) 2019 Elsevier B.V. All rights reserved.
In robust optimization, the parameters of an optimization problem are not deterministic but uncertain. Their values depend on the scenarios which may occur. Single-objective robust optimization has been studied extens...
详细信息
In robust optimization, the parameters of an optimization problem are not deterministic but uncertain. Their values depend on the scenarios which may occur. Single-objective robust optimization has been studied extensively. Since 2012, researchers have been looking at robustness concepts for multi-objective optimization problems as well. In another line of research, single-objective uncertain optimization problems are transformed to deterministic multi-objective problems by treating every scenario as an objective function. In this paper we combine these two points of view. We treat every scenario as an objective function also in uncertain multi-objective optimization, and we define a corresponding concept of dominance which we call multi scenario efficiency. We sketch this idea for finite uncertainty sets and extend it to the general case of infinite uncertainty sets. We then investigate the relation between this dominance and the concepts of highly, locally highly, flimsily, and different versions of minmax robust efficiency. For all these concepts we prove that every strictly robust efficient solution is multi-scenario efficient. On the other hand, under a compactness condition, the set of multi-scenario efficient solutions contains a robust efficient solution for all these concepts which generalizes the Pareto robustly optimal (PRO) solutions from single-objective optimization to Pareto robust efficient (PRE) solutions in the multi-objective case. We furthermore present two results on reducing an infinite uncertainty set to a finite one which are a basis for computing multi scenario efficient solutions. (C) 2018 Elsevier B.V. All rights reserved.
暂无评论