It is common to schedule project activities first, then the utilization of equipment and its operating crew is planned based on such schedule. Real world experiences indicate that activity scheduling can be heavily im...
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It is common to schedule project activities first, then the utilization of equipment and its operating crew is planned based on such schedule. Real world experiences indicate that activity scheduling can be heavily impacted by the resources needed. In particular, if a project requires highly specialized and expensive equipment type, then one needs to take into account the schedule and cost of such resources in developing the project schedule. In this paper, we consider the impact of using expensive and specialized equipment on the project schedule and its cost. The integration of project scheduling with equipment planning introduces new trade-offs that would lead to more realistic and cost-effective project schedules. Such trade-offs include the costs of: activity crashing, equipment setup, transition, idle time, and operator's overtime as well as the project worth;rewards for early completion and penalty for delayed completion. An efficient mixedinteger linear program is developed to capture the real world considerations of the integrated problem. The solution of the program yields the optimal schedules for the activities, equipment, and operators. These schedules involve crashing of critical and non-critical activities. An efficient heuristic is also developed and used to schedule large size projects. Optimal schedules are analyzed and computational experiences are provided. Published by Elsevier B.V.
Quay crane scheduling a yard truck scheduling are two important subproblems in container terminal operations, which have been studied separately in previous research. This paper treats the scheduling of quay crane and...
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ISBN:
(纸本)9781424426294
Quay crane scheduling a yard truck scheduling are two important subproblems in container terminal operations, which have been studied separately in previous research. This paper treats the scheduling of quay crane and yard truck in a whole. The problem is formulated as a mixed integer programming model and solved with a genetic algorithm. Computational examples show the benefits of integrated methods and the efficiency of the proposed algorithm.
The problem of determining the sequence of stops and the amount of load to carry in each segment route, named the Multi-Stop Routing Problem (MSRP) is addressed. A 0/1 mixedinteger linear program and formulation refi...
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The problem of determining the sequence of stops and the amount of load to carry in each segment route, named the Multi-Stop Routing Problem (MSRP) is addressed. A 0/1 mixedinteger linear program and formulation refinements which facilitate the solution process are presented. Since the constraint set of the MSRP includes 0/1 mixed rows, valid inequalities for this type of regions are presented. Then these results are applied to the constraint set of the routing problem, presenting additional valid inequalities. In addition, polynomial separation algorithms associated with the valid inequalities are given, computational results are also included.
Second generation biofuels from wood gasification are thought to become competitive in the face of effective climate and energy security policies. Cost competitiveness crucially depends on the optimization of the enti...
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Second generation biofuels from wood gasification are thought to become competitive in the face of effective climate and energy security policies. Cost competitiveness crucially depends on the optimization of the entire supply chain-field-wheel involving optimal location, scaling and logistics. In this study, a linear mixed integer programming model has been developed to determine the optimal geographic locations and sizes of methanol plants and gas stations in Austria. Optimal locations and sizes are found by the minimization of costs with respect to biomass and methanol production and transport, investments for the production plants and the gas stations. Hence, the model covers competition in all levels of a biofuel production chain including supply of biomass, biofuel and heat, and demand for bio- and fossil fuels. The results show that Austria could be self-sufficient in the production of methanol for biofuels like M5, M10 or M20, using up to 8% of the arable land share. The plants are optimally located close to the potential supply of biomass (i.e. poplar) in Eastern Austria, and produce methanol around 0.4 is an element of(-1). Moreover, heat production could lower the methanol cost by 12%. Copyright (C) 2008 John Wiley & Sons, Ltd.
This paper introduces a mixedinteger mathematical model formulation for the "Carbon-Market Sensitive - Green Supply Chain Network Design" problem (CMS/GSCND) where carbon trading considerations are integrat...
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ISBN:
(纸本)9781424426294
This paper introduces a mixedinteger mathematical model formulation for the "Carbon-Market Sensitive - Green Supply Chain Network Design" problem (CMS/GSCND) where carbon trading considerations are integrated within the supply chain network design phase. The solution methodology allows the evaluation of different strategic decisions alternatives, such as supplier and subcontractor selection, product allocation, capacity utilization, and transportation configuration, and their impact in terms of carbon footprint. This new formulation provides decision makers with the ability to understand the trade-offs between total logistics costs and the impact of greenhouse gases reduction. It also allows offsetting the latter through both supply chain reengineering and carbon trading. Model validation, results, and extended analysis are demonstrated via a numerical study.
This paper discusses a novel approach for distributing a large number of multimedia (video) titles to users via a managed network infrastructure based on DSL technology. The approach, sometimes called push-VOD, is bas...
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ISBN:
(纸本)9781424417841
This paper discusses a novel approach for distributing a large number of multimedia (video) titles to users via a managed network infrastructure based on DSL technology. The approach, sometimes called push-VOD, is based on multicasting and the direct download of the content on user disks, followed by the local, but delayed playback of the video. We analyze in a first step the optimization problems related to the efficient packing of multicast trees on capacity constrained links. Then, we show that the model in which the user requests several alternative titles for download performs much better than the single title case. Finally, we consider the multiperiod scheduling performance and describe ways to reduce both the number of downloads of the same title and the delivery time of less frequent titles.
Based on the management goals of order planning of the iron-steel plants, a mixed integer programming model for the order planning is constructed The goals include balancing production capacity and minimizing the tota...
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ISBN:
(纸本)9780769533049
Based on the management goals of order planning of the iron-steel plants, a mixed integer programming model for the order planning is constructed The goals include balancing production capacity and minimizing the total cost of infringing contracts. As the data of orders and processes are put together to make a point graph, the problem of order planning is transferred into an improved Traveling Salesman Problem. An improved ant colony algorithm is presented to solve this model. The computational results show that the model comes up to the production processes, the satisfying solutions can be obtained within acceptable time.
This paper investigates the reverse logistics vehicle routing problem with a single depot, simultaneous distribution and collection of the goods by a homogeneous fleet of vehicles under the restrictions of maximum cap...
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ISBN:
(纸本)9781424417339
This paper investigates the reverse logistics vehicle routing problem with a single depot, simultaneous distribution and collection of the goods by a homogeneous fleet of vehicles under the restrictions of maximum capacities and maximum distance. A mixed integer programming model is constructed. To solve this problem, a mixed PSO (particle swarm optimization and simulated annealing) algorithm is designed. This paper designs the coding rules of initial solution, 2-opt information exchange strategy, neighborhood solution generation strategy and cooling schedule of SA algorithm strategy. The penalty function is used in the fitness function to avoid the generation of infeasible solutions. Taking one typical instances as example, the experimental study indicates that this approach could improve the vehicle load rate and get rid of the additional total distance caused by the fluctuating vehicle load and the limited capacity. The satisfying solutions can be obtained in acceptable computational time.
In the energy management of the isolated operation of small power system, the economic scheduling of the generation units is a crucial problem. Applying right timing can maximize the performance of the supply. The opt...
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ISBN:
(纸本)9781424419050
In the energy management of the isolated operation of small power system, the economic scheduling of the generation units is a crucial problem. Applying right timing can maximize the performance of the supply. The optimal operation of a wind turbine, a solar unit, a fuel cell and a storage battery is searched by a mixed-integer linear programming implemented in GAMS (General Algebraic Modeling Systems). A VPP (Virtual Power Producer) can optimal operate the generation units, assured the good functioning of equipment, including the maintenance, operation cost and the generation measurement and control. A central control at system allows a VPP to manage the optimal generation and their load control. The application of methodology to a real case study in Budapest Tech's, demonstrate the effectiveness of a this method to solve the optimal isolated dispatch of the DC microgrid renewable energy park. The problem has been converged in 0.09 seconds and 30 iterations.
In theory, a public utility company improves the quality of community life through its projects and actions. However, project selection and prioritization by these companies are highly complex processes. To assist com...
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