In this paper, we present two approaches to solve the relocation problem in one-way carsharing system. We start by formulating the problem as an Integer linearprogramming Model. Then using mobility data collected fro...
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ISBN:
(纸本)9781479944972
In this paper, we present two approaches to solve the relocation problem in one-way carsharing system. We start by formulating the problem as an Integer linearprogramming Model. Then using mobility data collected from an operational carsharing system, we built demands matrices that will be used as input data for our solver. We notice that the time needed to solve the ILP using an exact solver increases dramatically when we increase the number of employees involved in the relocation process and when the system gets bigger. To cope with this problem, we develop a greedy algorithm in order to solve the relocation problem in a faster time. Our algorithm takes one second to solve the relocation problem in worst cases;also, we evaluated the robustness of the two approaches with stochastic input data using different numbers of employees.
Many serious games include computational models that simulate dynamic systems. These models promote enhanced interaction and responsiveness. Under the social web paradigm more and more usable game authoring tools beco...
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ISBN:
(纸本)9783319121574;9783319121567
Many serious games include computational models that simulate dynamic systems. These models promote enhanced interaction and responsiveness. Under the social web paradigm more and more usable game authoring tools become available that enable prosumers to create their own games, but the inclusion of dynamic simulations remains a specialist's job involving knowledge of mathematics, numerical modeling and programming. This paper describes a methodology for specifying and running a specific subset of computational models without the need of bothering with mathematical equations. The methodology comprises a knowledge elicitation procedure for identifying and specifying the required model components, whereupon the mathematical model is automatically generated. The approach is based on the fact that many games focus on optimisation problems that are covered by a general class of linear programming models. The paper thus sketches the principles of a creativity tool that removes barriers for harvesting the creative potential of teachers and students.
This paper deals with the mathematical modelling of a scheduling problem in a heterogeneous CPU/FPGA architecture with communication delay in order to minimize the makespan, C-max. This study was motivated by the qual...
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ISBN:
(纸本)9782960053241
This paper deals with the mathematical modelling of a scheduling problem in a heterogeneous CPU/FPGA architecture with communication delay in order to minimize the makespan, C-max. This study was motivated by the quality of the available solvers for Mixed Integer Program. The proposed model includes the communication delay constraints in a general form in a heterogeneous case depending at the same time on tasks and computing units. These constraints are linearized without adding any extra variables and the obtained linear model is reduced to make its solving with Cplex 12.5x faster. Computational results show that the proposed model is promising. For an average sized problem up to 50 tasks and 5 computing units the solving time under Cplex is about few seconds.
The paper presents a multi-objective mixed integer linearprogramming model for portfolio selection of research and development (R and D) projects with synergies. Partial assignment of funds is allowed to different ta...
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The paper presents a multi-objective mixed integer linearprogramming model for portfolio selection of research and development (R and D) projects with synergies. Partial assignment of funds is allowed to different tasks of the project, while synergies are considered at the task and the project level. A synergy is active if a number of its elements sufficiently supported is within certain bounds. The risk associated with insufficient support is introduced. Numerical results are presented to demonstrate the efficiency of the proposed approach for large scale instances.
Farm households in the Andean region of South America face serious livelihood challenges, including a poor natural resource base and declining agricultural yields. Conservation agriculture has been identified as a pot...
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Farm households in the Andean region of South America face serious livelihood challenges, including a poor natural resource base and declining agricultural yields. Conservation agriculture has been identified as a potential solution to environmental degradation and the associated poverty and food insecurity in the region. This study analyses the potential economic impact of conservation agriculture in two sub-watersheds in central Ecuador utilizing a linearprogramming model and data from experiments in farmer fields. The model found that specific cover crops, crop rotations and reduced tillage designed to reduce soil erosion and increase soil organic matter can lead to increased incomes for farm households in a time period of as short as two years. It appears that conservation agriculture practices have the potential to improve the livelihoods of the rural poor in Ecuador because conservation agriculture activities entered the revenue-maximizing model solution for both sub-watersheds.
Interval multiplicative preference relation is very useful in expressing decision maker's preferences on alternatives under uncertain preference information. How to derive priorities from a interval multiplicative...
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ISBN:
(纸本)9781424423873
Interval multiplicative preference relation is very useful in expressing decision maker's preferences on alternatives under uncertain preference information. How to derive priorities from a interval multiplicative preference relation is an interesting and important issue in decision making. In this paper,we first define the concepts of interval multiplicative preference relations, consistent interval multiplicative preference relations, and then propose some simple and practical linear programming models, based on consistent interval multiplicative preference relations for obtaining the priority vector of interval multiplicative preference relations. These linear programming models are also extended to obtain the collective priority vector of several interval multiplicative preference relations. Finally, the proposed models are tested and examined with two numerical examples and prove to be simple, effective and practical.
Deriving priority weights from fuzzy preference relations is a significant issue in decision making problems. In this paper, based on the definition of additive consistent fuzzy preference relations proposed by Tanino...
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Deriving priority weights from fuzzy preference relations is a significant issue in decision making problems. In this paper, based on the definition of additive consistent fuzzy preference relations proposed by Tanino, a new approach with a parameter is developed to obtain priority weights, and properties of the new approach are explored. Then, a method for correcting inconsistent fuzzy preference relations is derived, and a new definition for the additive consistent interval fuzzy preference relations is obtained for the interval complementary pairwise comparison matrix. From these, linear programming models for generating interval priority weights from additive consistent or inconsistent interval fuzzy preference relations are established. Finally, three numerical examples are examined to show the feasibility of the developed method, and comparisons are also made between this new approach and the methods proposed by Xu and Chen [15]. Through the numerical examples, the ranking of interval priority weights using the different methods was found to be the same but with a slightly different degree of possibility. However, for the same interval complementary pairwise comparison matrix, the new definition for additive consistent interval fuzzy preference relations proposed in this paper was found to have more consistent information. (C) 2011 Elsevier B.V. All rights reserved.
In this study, the authors propose the formalisation of the Simultaneous Slot Allocation Problem (SSAP), that extends, in two directions, the current way of allocating airport slots in Europe. The SSAP requires, first...
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In this study, the authors propose the formalisation of the Simultaneous Slot Allocation Problem (SSAP), that extends, in two directions, the current way of allocating airport slots in Europe. The SSAP requires, first, to perform the slot allocation at all airports simultaneously and, second, to respect airspace sector capacities. The authors solve the SSAP with two algorithms based on metaheuristics, namely Iterated Local Search and Variable Neighborhood Search, and with an algorithm based on an integer linearprogramming model. They compare these algorithms on randomly generated instances and show that for small instances metaheuristics are competitive with the integer linearprogramming model. Nevertheless, the integer linearprogramming model is unable to solve medium or large instances because of memory and computation time requirements. Metaheuristics, instead, can deal with large instances, allocating slots to more than 99.8% of flights.
The Instituto para el Depósito de Valores (INDEVAL) is the Central Securities Depository of Mexico. It is the only Mexican institution authorized to perform, in an integrated manner, the activities of safe-keepin...
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Wireless Body Area Networks (WBANs) represent one of the most promising approaches for improving the quality of life, allowing remote patient monitoring and other healthcare applications. In such networks, traffic rou...
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ISBN:
(纸本)9781457720529
Wireless Body Area Networks (WBANs) represent one of the most promising approaches for improving the quality of life, allowing remote patient monitoring and other healthcare applications. In such networks, traffic routing plays an important role together with the positioning of relay nodes, which collect the information from biosensors and send it towards the sinks. This work investigates the optimal design of wireless body area networks by studying the joint data routing and relay positioning problem in a WBAN, in order to increase the network lifetime. To this end, we propose an integer linearprogramming model which optimizes the number and location of relays to be deployed and the data routing towards the sinks, minimizing both the network installation cost and the energy consumed by wireless sensors and relays. We solve the proposed model in realistic WBAN scenarios, and discuss the effect of different parameters on the characteristics of the planned networks. Numerical results demonstrate that our model can design energy-efficient and cost-effective wireless body area networks in a very short computing time, thus representing an interesting framework for the WBAN planning problem.
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