Optimization problems arise in many contexts. Sometimes finding a good formulation takes considerable effort. A modeling language, such as AMPL, facilitates experimenting with formulations and simplifies using suitabl...
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ISBN:
(纸本)9783319176895;9783319176888
Optimization problems arise in many contexts. Sometimes finding a good formulation takes considerable effort. A modeling language, such as AMPL, facilitates experimenting with formulations and simplifies using suitable solvers to solve the resulting optimization problems. AMPL lets one use notation close to familiar mathematical notation to state variables, objectives, and constraints and the sets and parameters that may be involved. AMPL does some problem transformations and makes relevant problem information available to solvers. The AMPL command language permits computing and displaying information about problem details and solutions returned by solvers. It also lets one modify problem formulations and solve sequences of problems. AMPL addresses both continuous and discrete optimization problems and offers some constraint-programming facilities for the latter. More generally, AMPL permits stating and solving problems with complementarity constraints. For continuous problems, AMPL makes first and second derivatives available via automatic differentiation. The freely available AMPL/solver interface library (ASL) facilitates interfacing with solvers. This paper gives an overview of AMPL and its interaction with solvers and discusses some problem transformations and implementation techniques. It also looks forward to possible enhancements to AMPL.
Purpose Airlines use various analytical techniques to optimally control seats in its various fare classes. Most literature on inventory control does not discuss policies for group arrivals. This study aims to address ...
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Purpose Airlines use various analytical techniques to optimally control seats in its various fare classes. Most literature on inventory control does not discuss policies for group arrivals. This study aims to address the literature gap in determining an optimal booking policy which considers the dynamics of group behaviour with respect to cancellations and refunds. Design/methodology/approach An analytical model by which bid price control mechanism can be applied to group bookings is developed through this study. Findings Numerical experiments are performed to demonstrate the analytical model under various scenarios. A comparison of the model with the traditional model indicates an increase in the total revenue generated. Originality/value The novelty of this work is in modelling the dynamics of group behaviour in a network of flights, and it contributes to the literature on revenue management.
Selecting appropriate sites for municipal solid waste (MSW) is a challenging problem for urban communities and has economic and environmental implications. This paper proposes a mathematical optimization model to solv...
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Selecting appropriate sites for municipal solid waste (MSW) is a challenging problem for urban communities and has economic and environmental implications. This paper proposes a mathematical optimization model to solve the location problem of MSW sites incorporating both push and pull characteristics. Four objective functions comprising health, safety, environmental (HSE), and economic indicators are considered. These objectives are combined into a single objective function using the weighted sum method and the best method is selected based on noise analysis. The parameter uncertainty is incorporated into the model using expert judgments followed by sensitivity analysis to show the effect of the most important parameters. Using the data from a network of 360 population centers in Tehran, the solution for the model is demonstrated. To our knowledge, this is the first study on location optimization of MSW considering combined HSE and economic indicators. The proposed approach is flexible and parsimonious.
Let us consider a function {mathematical expression} where the functions fij(z) are supposed to be continuously differentiable and real-valued on a set Ω of En, z∂En. The problem is to find maxze{open}Ωφ{symbol}(z)...
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Cloud computing and storage have attracted a lot of attention due to the ever increasing demand for reliable and cost-effective access to vast resources and services available on the Internet. Cloud services are typic...
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ISBN:
(纸本)9783981537024
Cloud computing and storage have attracted a lot of attention due to the ever increasing demand for reliable and cost-effective access to vast resources and services available on the Internet. Cloud services are typically hosted in a set of geographically distributed data centers, which we will call the cloud infrastructure. To minimize the total cost of ownership of this cloud infrastructure (which accounts for both the upfront capital cost and the operational cost of the infrastructure resources), the infrastructure owners/operators must do a careful planning of data center locations in the targeted service area (for example the US territories), data center capacity provisioning (i.e., the total CPU cycles per second that can be provided in each data center). In addition, they must have flow control policies that will distribute the incoming user requests to the available resources in the cloud infrastructure. This paper presents an approach for solving the unified problem of data center placement and provisioning, and request flow control in one shot. The solution technique is based on mathematical programming. Experimental results, using Google cluster data and placement/provisioning of up to eight data center sites demonstrate the cost savings of the proposed problem formulation and solution approach.
This paper presents equilibrium conditions of multiparty information exchange problems. Pieces of information are exchanged among parties in a fair, peer-to-peer, private and simultaneous manner. The idea is so that a...
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ISBN:
(纸本)9781467366014
This paper presents equilibrium conditions of multiparty information exchange problems. Pieces of information are exchanged among parties in a fair, peer-to-peer, private and simultaneous manner. The idea is so that at the end each party can construct secrets from what it receives. These secrets can either be false or true, which yield negative or positive payoffs. By formalising, we demonstrate that although cheating is a dominant strategy, there might be other less trivial equilibria in which parties are reluctant to information exchange. We devise a method for computing generalized equilibria, based on solving MLIP models. The necessary and sufficient conditions for the equilibrium existence can be tested by the MLIP model. We present case studies that illustrate our model features, essentially with multiple equilibria and with more than five players. The running time is exponential in the number of players and polynomial in the number of information pieces.
In this paper, we describe a general non-simplex type algorithm for determining all essential solutions and inequalities for any convex polyhedron defined either in a tangential or in a barycentric form. This algorith...
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This paper proposes a framework to recommend personal sightseeing route as well as to objectively obtain the tourist's utility to sightseeing plans and sightseeing spots from subjective comparison. The subjective ...
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ISBN:
(纸本)9781467389853
This paper proposes a framework to recommend personal sightseeing route as well as to objectively obtain the tourist's utility to sightseeing plans and sightseeing spots from subjective comparison. The subjective comparison is qualitatively performed using a scale of measurement such as Likert scale, and the mathematical programming problem including this comparison as constraints is introduced. In the case of route planning, traveling and sightseeing times are randomly changed dependent on current traffic and congestion conditions, and hence, Time-Expanded Network (TEN) to represent these traffic conditions in the underlying static network with each discrete time step is introduced. In addition, the network optimization problem is introduced to obtain the personal appropriate sightseeing route. This problem is formulated as a nonlinear and discrete optimization problem, and it is hard to solve it directly and efficiently. Therefore, an efficient algorithm is also developed based on dynamic programming and transformation of the main problem into the recursive equation.
The potential price for enabling network slicing in multi-tenant virtualized mobile networks is the underutilization of the scarce wireless and/or network resources. One way to increase overall network utilization wou...
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ISBN:
(纸本)9781538617342
The potential price for enabling network slicing in multi-tenant virtualized mobile networks is the underutilization of the scarce wireless and/or network resources. One way to increase overall network utilization would be to allow inter-tenant sharing, i.e., sharing of resources between different network slices. To this end, this work tries to shed further light into this issue by discussing different possible degrees of network sharing together with the associated linear integer mathematical programs that allows to investigate upper bounds on the achievable performance improvement. Furthermore, in order to realize real time and adaptive sharing of resources a scale-free heuristic is also presented that is amenable for real-time implementation. Based on the depth of the aforementioned multitenant sharing, we propose a sharing scheme with two options named Tight Coupling (TX) and Loose Coupling (LX). Under the 3GPP baselines and certain assumptions, a set of numerical investigations have been carried out demonstrating significant gain in aggregated network throughput and per user throughput compared to traditional fully isolated network slicing method.
This survey considers the application of Operational Research techniques to the solution of packing problems. Such problems arise in a variety of situations including pallet loading, container stuffing and placement p...
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This survey considers the application of Operational Research techniques to the solution of packing problems. Such problems arise in a variety of situations including pallet loading, container stuffing and placement problems. The focus of this paper is on the modelling and solution of problems in two and three dimensions and a number of exact and heuristic approaches are reviewed.
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