Vehicular network is one of the most important subjects for researchers in recent years. Anycast routing protocols have many applications in vehicular ad hoc networks. The aim of an anycast protocol is sending packets...
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Vehicular network is one of the most important subjects for researchers in recent years. Anycast routing protocols have many applications in vehicular ad hoc networks. The aim of an anycast protocol is sending packets to at least one of the receivers among candidate receivers. Studies done on anycast protocols over vehicular networks, however, have capability of implementation on some applications;they are partial, and application specific. No need to say that the lack of a comprehensive study, having a strong analytical background, is felt. Mathematical modeling in vehicular networks is difficult because the topology of these networks is dynamic. In this paper, it has been demonstrated that vehicular networks can be modeled based on time-expanded networks. The focus of this article is on geographical anycast. Three different scenarios were proposed including sending geographic anycast packet to exactly-one-destination, to at-least-one-destination, and to K-anycast destination, which can cover important applications of geographical anycast routing protocols. As the proposed model is of MILP type, a decentralized heuristic algorithm was presented. The evaluation process of this study includes the production of numerical results by branch and bound algorithm in general algebraic modeling system (GAMS) software and simulation of the proposed protocol in OMNET++ simulator. The comprehension of the result of proposed protocol and model shows that the applicability of this proposed protocol and its reactive conformity with the presented models based on presented metrics.
Along with the rising prevalence of chronic diseases and the increasing complexity of pharmaceutical care, pharmacy automation dispensing systems (PADS)s are utilized to improve the quality of patient care, reduce dis...
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Along with the rising prevalence of chronic diseases and the increasing complexity of pharmaceutical care, pharmacy automation dispensing systems (PADS)s are utilized to improve the quality of patient care, reduce dispensing-related medication errors, and cut down medication-related expenses. After PADSs fulfill prescription orders, patients still have to dispense medications for each meal by themselves. It is well known that dispensing medications is time-consuming and exhausting, especially for chronic patients. During the manual dispensing process, some unexpected medical errors might appear, which would result in discomfort, harm, and even death. To provide efficient and patient-centered pharmacy care, we proposed automatically dispensing prescriptions by meal orders in PADS. Specifically, we formulated a novel three-stage assembly flowshop problem to fulfill prescription orders at the level of meal orders to minimize the total completion times of packing prescription orders. In our studied PADS, there are fully flexible parallel machines dispensing medication jobs and collating sub-orders (meal prescription orders) in the first and second stages, and one assembly machine packing prescription orders in the third stage. Based on the properties of the optimal schedule, we proposed a branch-and-bound (B&B) algorithm embedded with a constructive heuristic (CH) to obtain a fight upper bound. Since the three-stage assembly flowshop problem in PADS is strongly NP-hard, we also presented an improved tabu search (iTS) heuristic for the practical data size. Finally, we conducted a series of numerical experiments based on artificial data sets guided by characteristics obtained from practical pharmacy data sets. The computational results showed that the proposed CH algorithm is efficient, and when the computational time was allowed, the iTS algorithm could further enhance the performance. Moreover, the efficiency of collating sub-orders has a significant impact on the overa
Index tracking is a very common and popular approach in portfolio management. When there is neither (nonconvex) transaction costs nor minimal transaction unit constraints, the problem can be formulated as a convex lea...
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Index tracking is a very common and popular approach in portfolio management. When there is neither (nonconvex) transaction costs nor minimal transaction unit constraints, the problem can be formulated as a convex least square problem, so that it can be solved by standard methods. However, when the transaction cost is nonconvex and not negligible, or if there is a minimal unit constraint on the amount of transaction, the problem becomes a nonconvex minimization problem with discrete variables. In this paper, we will propose a branch and bound algorithm for solving this class of problems and show that it can solve an index tracking problem of practical size in a reasonable amount of computation time.
The topic of this paper is the cyclic job shop problem which aims at minimizing the cycle time under precedence and resource constraints. Based on graph theory, we propose a new branch and bound enumeration procedure ...
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The topic of this paper is the cyclic job shop problem which aims at minimizing the cycle time under precedence and resource constraints. Based on graph theory, we propose a new branch and bound enumeration procedure to solve this problem. We compare the new procedure with other exact methods and present numerical test results.
Urban intersections are key locations of traffic crashes that contribute significantly to the economic losses. Safety management process undertaken by most states in the United States (U.S), is often referred to as th...
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Urban intersections are key locations of traffic crashes that contribute significantly to the economic losses. Safety management process undertaken by most states in the United States (U.S), is often referred to as the hazard elimination program which consists of three steps: (1) selections of hazardous locations, (candidate locations) where safety improvements are warranted, (2) development of countermeasures for potential reduction of crashes, (3) allocation of resources among the independent candidate locations in conformance to budgetary and other constraints. Often these three steps are independently considered with very limited detail on each step in the state planning agencies. This paper presents a simultaneous model which predicts the occurrence of crashes and allocates resources by maximizing benefits subjected to budget and other constraints. The analysis is carried out for a planning period of five years. The crash prediction is analysed as a negative binomial model. The resource allocation model is solved using branch and bound algorithm. Prediction and allocation is conducted simultaneously to achieve realistic results rather than analysing both steps independently. The allocation model further prioritizes the projects to be implemented to optimally distribute funds to maximize benefits. Model results reveal that the proposed approach can be used as a tool for resource allocation on highway safety projects for urban intersections.
We study assembly systems with one type of finished products and several types of components. The lead times of components are random variables, and the customer demand of finished product is constant. We proposed a M...
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We study assembly systems with one type of finished products and several types of components. The lead times of components are random variables, and the customer demand of finished product is constant. We proposed a Markov chain that enables the determination of system performance measures, and we show how to exploit this model for optimization. Our aim is to minimize the average holding cost for the components while keeping a given service level for customer demands. In this paper we propose lower bounds and dominance properties of goal function. These results can be used in a branch and bound algorithm.
This paper provides a design method for two-degrees-of-freedom PID controllers including switched PD compensator based on bilinear matrix inequalities (BMIs). Two design specifications based on H 2 norm are formulated...
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This paper provides a design method for two-degrees-of-freedom PID controllers including switched PD compensator based on bilinear matrix inequalities (BMIs). Two design specifications based on H 2 norm are formulated in BMIs, and PID parameters can be exactly obtained by solving the BMI problems via branch and bound algorithms. A set of PD compensators can be obtained simultaneously by using proposed design method. The most effective parameter is selected out of the set of PD compensator based on the switching criterion which obtained from estimated system conditions using recursive least square algorithms. Numerical example is also shown.
Technological advancement, the emergence of more complex production systems, and the need for greater manufacturer competition have caused production systems to shift from a centralized environment to a decentralized ...
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Technological advancement, the emergence of more complex production systems, and the need for greater manufacturer competition have caused production systems to shift from a centralized environment to a decentralized one. Researchers have paid more attention to distributed flow shop scheduling problems and investigated various features and issues related to them in recent years. However, special types of these problems, in which the network structure is serial and inter-factory transportation is significant, have received less attention. This study investigated the two-machine decentralized flow shop scheduling problem, in which inter-factory transportation is handled by a batch delivery system. The goal was to simultaneously reduce the costs of makespan and batch delivery. A mixed-integer linear programming model capable of solving small-size instances in a logical running time was presented to better describe the problem. Then, in order to solve large-size instances in a logical running time, a fast branch and bound algorithm with a heuristic method were developed to obtain the appropriate upper bound as well as the tight lower bounds at each node. The computational results indicated that the B&B algorithm performed very well in terms of problem-solving running time. The findings also demonstrated that the heuristic method can solve the most complex instances by 100 jobs with less than 13% error.
The optimization of scheduling problems is based on different criteria to optimize. One of the most important criteria is the minimization of completion time of the last task on the last machine called makespan. In th...
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The optimization of scheduling problems is based on different criteria to optimize. One of the most important criteria is the minimization of completion time of the last task on the last machine called makespan. In this paper, we present a parallel algorithm for solving the permutation flow shop problem. Our algorithm is a basic parallel distributed algorithm deployed in a grid of computer (Grid' 5000). The objective of this work is minimizing the total makespan of the tasks. Our algorithm uses the exact branch and bound method to find optimal solutions of the problem through the distribution of the tasks among the available processors. Computational results of our parallel algorithm using well known Taillard's benchmarks, showed encouraging results. In particular, we succeeded to solve two new instances to optimality which had never been resolved before neither in sequential nor in parallel [29].
Nash Equilibrium is the solution of the Cournot Model considering the reaction functions provided that outputs are *** in practice,the outputs of some products are not *** improved branch and bound algorithm is propos...
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Nash Equilibrium is the solution of the Cournot Model considering the reaction functions provided that outputs are *** in practice,the outputs of some products are not *** improved branch and bound algorithm is proposed combining the Nash Equilibrium,considering the discontinuous *** proposed algorithm is different from the traditional algorithm where the respond functions would be converted into *** the improved algorithm is used to calculate the output of each manufacturer,the worst solution arising in the mid-process of calculation will be removed firstly,and then the final common integer solution of all manufactures will be the optimal *** procedure of the proposed algorithm is explicated in this *** example where two manufactures exist is studied,and the results validate the effectiveness of the method.
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