In this paper, a nonconvex multiobjective optimization problem with Lipschitz objective functions is considered. A branch and bound algorithm that incorporates the decision maker's preference information is propos...
详细信息
In this paper, a nonconvex multiobjective optimization problem with Lipschitz objective functions is considered. A branch and bound algorithm that incorporates the decision maker's preference information is proposed for this problem. In the proposed algorithm, a new discarding test is designed to check whether a box contains preferred solutions according to the preference information expressed by means of reference points. In this way, the proposed algorithm is able to gradually guide the search towards the region of interest on the Pareto fronts during the solution process. We prove that the proposed algorithm obtains e-efficient solutions distributed among the regions of interest with respect to the given reference points. Moreover, lower bound on the total finite number of required iterations for predefined precision is also provided. Finally, the algorithm is illustrated with a number of test problems.
The branch and bound (BB) algorithm, while ensuring optimality, often encounters performance bottlenecks, characterized by slow execution and high computational overhead, especially when dealing with intricate or exte...
详细信息
The branch and bound (BB) algorithm, while ensuring optimality, often encounters performance bottlenecks, characterized by slow execution and high computational overhead, especially when dealing with intricate or extensive problem instances (NP-Hard). This study introduces an innovative approach by dividing the problem into partial (local) problems in a manner that would not compromise optimality and solving sub-problems of each local problem individually, to shrink the solution space. In the initial phase, this research establishes and validates the mathematical foundation of the proposed algorithm, which involves a pruning approach. Subsequently, enhancements are incorporated into the existing BB to partition the solution space into more manageable sub-spaces and consolidate solutions from these sub-spaces. In the final phase, the Enhanced branch and bound (EBB) algorithm is applied to a real-world power dispatching optimization case study. The outcomes of this investigation reveal the following: 1) For smaller problem instances, both the conventional BB and the proposed EBB algorithm yield identical optimal solutions. 2) In contrast, the EBB algorithm demonstrates significantly improved performance in solving NP-hard problems that pose challenges for the BB and BB with pruning. The primary contribution of this research is the introduction of EBB, an enhanced version of BB, specifically designed to effectively tackle NP-hard problems. This approach can be integrated with all pruning, branching, and bounding strategies used in BB, thereby boosting its performance and making it applicable to all problems solved by BB variations.
Flexible manufacturing systems (FMSs), which can easily adapt to changes in job types, have been widely used in manufacturing areas. Scheduling of FMSs is a variant of a flexible job shop with transport robots and no ...
详细信息
Flexible manufacturing systems (FMSs), which can easily adapt to changes in job types, have been widely used in manufacturing areas. Scheduling of FMSs is a variant of a flexible job shop with transport robots and no buffer, and it is extremely hard as it involves determining the job processing sequence on machines and the sequence of robot tasks, with various jobs with different processing flows and the risk of deadlocks. Due to these characteristics, many existing studies have focused on developing heuristic algorithms. However, an optimal solution is still crucial to minimize FMSs makespan. Therefore, we propose a mixed integer programming (MIP) and a branch and bound (B & B) algorithm with a timed Petri net (TPN) to achieve optimal scheduling of FMSs. FMSs are first modeled with a TPN, and tight lower bounds are proposed based on bottleneck machines and sophisticated ready times. In addition, the search space is effectively reduced by the transition index marking (TIM)-based dominance rule and various deadlock prevention conditions based on the TPN. The experimental results show that our proposed B & B algorithm outperforms mathematical formulation and previous algorithms in various FMS instances
The branch and bound (BB) algorithm is widely used to obtain the global solution of mixed-integer linear programming (MILP) problems. On the other hand, when the traditional BB structure is directly used to solve nonc...
详细信息
The branch and bound (BB) algorithm is widely used to obtain the global solution of mixed-integer linear programming (MILP) problems. On the other hand, when the traditional BB structure is directly used to solve nonconvex mixed-integer nonlinear programming (MINLP) problems, it becomes ineffective, mainly due to the nonlinearity and nonconvexity of the feasible region of the problem. This article presents the difficulties and ineffectiveness of the direct use of the traditional BB algorithm for solving nonconvex MINLP problems and proposes the formulation of an efficient BB algorithm for solving this category of problems. The algorithm is formulated taking into account particular aspects of nonconvex MINLP problems, including (i) how to deal with the nonlinear programming (NLP) subproblems, (ii) how to detect the infeasibility of an NLP subproblem, (iii) how to treat the nonconvexity of the problem, and (iv) how to define the fathoming rules. The proposed BB algorithm is used to solve the transmission network expansion planning (TNEP) problem, a classical problem in power systems optimization, and its performance is compared with the performances of off-the-shelf optimization solvers for MINLP problems. The results obtained for four test systems, with different degrees of complexity, indicate that the proposed BB algorithm is effective for solving the TNEP problem with and without considering losses, showing equal or better performance than off-the-shelf optimization solvers.
In the current era of multimedia, television (TV) plays an important role in transmitting advertising messages. In addition, advertising is the primary source of revenue for the TV industry. Thus, a critical issue for...
详细信息
In the current era of multimedia, television (TV) plays an important role in transmitting advertising messages. In addition, advertising is the primary source of revenue for the TV industry. Thus, a critical issue for TV stations is the scheduling of commercials in suitable advertising breaks on different TV channels to maximize revenue and minimize penalties. This type of TV commercial scheduling problem is similar to the machine scheduling problem, and both have availability constraints. However, the literature on TV commercial scheduling has not considered this perspective. Motivated by this, we consider the problem of scheduling commercials with specific service-level requirements on TV channels while minimizing the maximum lateness. The lateness of a commercial is defined to be its completion time minus its due date, and the maximum lateness is the maximum value of lateness among all commercials. We propose an exact branch and bound algorithm based on the LFJ (least flexible job first)/EDD (earliest due date first) rules and network flow methods, which were developed to solve the machine scheduling problem with availability constraints. Computational analysis shows that the bounding scheme proposed is highly effective, and a very low percentage of nodes is generated by the branch and bound algorithm. The algorithm can obtain an optimal solution for the problem.
In this paper described of assignment cost for the numbers that are fuzzy. Here, the assignment problem, which is fuzzy or invalid, is turned into crisp values throughout robust ranking technique, and by using branch ...
详细信息
In this paper described of assignment cost for the numbers that are fuzzy. Here, the assignment problem, which is fuzzy or invalid, is turned into crisp values throughout robust ranking technique, and by using branch and bound algorithm we gated the optimal solution and at a less *** applied example is taken from Source No. (9) to solving the assignment problem for the Cotton Industries Company in Iraq and find the optimal assignment and total cost.
This paper addresses a two-machine no-wait flowshop problem with the effect of the truncated learning function of jobs whose actual processing times depend on their positions in the sequence. By considering truncated ...
详细信息
This paper addresses a two-machine no-wait flowshop problem with the effect of the truncated learning function of jobs whose actual processing times depend on their positions in the sequence. By considering truncated learning effect, the actual processing time of a job is a function of its position index in the schedule and a control parameter. In a production scenario with truncated learning effect, the actual processing time of a job will not be lower than a threshold when the number of processed jobs increases. We develop a branch and bound algorithm to minimize the makespan. A lower bound and a dominance property have been proposed to increase the speed of elimination process in the branch and bound algorithm.
In this paper, a methodology to solve the optimal reactive power dispatch (ORPD) in electric power systems (EPS), considering discrete controllers, is proposed. Discrete controllers, such as the tap position of on-loa...
详细信息
In this paper, a methodology to solve the optimal reactive power dispatch (ORPD) in electric power systems (EPS), considering discrete controllers, is proposed. Discrete controllers, such as the tap position of on-load tap changing (OLTC) transformers and switchable reactive shunt compensation, are optimized by the proposed method. A semidefinite relaxation (SDR) of the ORPD problem and a branch-and-bound (B&B) algorithm have been fully deployed. A new formulation is presented for the OLTC transformers to obtain a connected structure of the semidefinite programming (SDP) matrices. The customized B&B algorithm deals with the discrete nature of the binary control variables. Moreover, in order to enhance the convexification, valid inequalities called lifted nonlinear cuts (NLC) are implemented in the SDR. Additionally, a chordal decomposition technique is used to improve the computational performance. Finally, the B&B algorithm is used to solve the mixed-integer semidefinite programming problem. Several benchmarks have been used to show the accuracy and scalability of the proposed method, and convergence analysis shows that near-global optimal solutions are generated with small relaxation gaps.
The use of information technology in the e-Learning process gives positive and negative impacts. One of the positive impacts is the easy access for vast information;while the negative impacts is the ineffective learni...
详细信息
ISBN:
(纸本)9781728152929
The use of information technology in the e-Learning process gives positive and negative impacts. One of the positive impacts is the easy access for vast information;while the negative impacts is the ineffective learning because it makes students lazy. Previous research has used games or game elements to decrease the negative impacts of e-Learning. A survey about algorithm Design and Analysis course was conducted, and it shows that there are some difficult subjects that need to be taught using an alternative method of learning. This research discusses how to design a video game in order to learn branch and bound algorithm and evaluate the game produced with the design. First, online surveys were done to gather the requirement, then the game design was made, then the game was implemented and evaluated. The evaluation would be used to make a better design for the next development iteration. The result of playtesting shows positive feedbacks and receives critics and suggestions. This research finds that designing a good game for learning is hard because developer must carefully define all elements in the game, so that everything is balanced and complements each other.
In this paper, we study a novel self-driving travel planning problem, where the tourist aims to minimize the total cost. The idea is to use a mathematical model to planning a route-time scheme for travel spots and hot...
详细信息
ISBN:
(纸本)9781538675182
In this paper, we study a novel self-driving travel planning problem, where the tourist aims to minimize the total cost. The idea is to use a mathematical model to planning a route-time scheme for travel spots and hotels. Specifically, this planning determines the tour for travel spots and considers the hotel selection under the rest break constraint, as well as schemes routes and time arrangement for the trip. Meanwhile, based on real-time and multi-resource demand, we use multi-resource data to execute multiple websites' information extraction. We utilize two algorithms to solve the proposed problem and make a comparison, one is exact branch and bound scheme and the other is the branch and bound based heuristic algorithm. In the proposed heuristic algorithm, the travel spots in the problem are decomposed by K-means algorithm, then each group of travel spots is bounded by the greedy algorithm and Hungarian method for upper bound and lower bound, respectively. Each branch node branches using Hungarian method and each branch can be treated as an assignment problem solved by Hungarian method. Finally, we give numerical examples and discuss the results.
暂无评论