Search results for " operations"
showing 10 items of 1066 documents
The shortest-path problem with resource constraints with -loop elimination and its application to the capacitated arc-routing problem
2014
Abstract In many branch-and-price algorithms, the column generation subproblem consists of computing feasible constrained paths. In the capacitated arc-routing problem (CARP), elementarity constraints concerning the edges to be serviced and additional constraints resulting from the branch-and-bound process together impose two types of loop-elimination constraints. To fulfill the former constraints, it is common practice to rely on a relaxation where loops are allowed. In a k-loop elimination approach all loops of length k and smaller are forbidden. Following Bode and Irnich (2012) for solving the CARP, branching on followers and non-followers is the only known approach to guarantee integer …
Networking strategy for competitive advantage
2011
This paper explores the potential of networking strategy as a source of competitive advantage by integrating market- based and resource-based logics. It contributes to operations management literature by considering not just supply chain structures but also others kinds of network that can emerge from horizontal agreements (i.e. alliances, partnerships, joint ventures, etc.). The paper reviews the literature and develops propositions regarding how make/buy/make together decisions, governance mechanisms and network-base structures allow firms both to pursue operations performance objectives and obtain/create valuable resources. A case study supports the propositions and shows a practical app…
Evolution of Telecom Operator Software Industry: Conclusions and Future
2009
Analysis of software industry is a challenging task due to the inherent characteristics of software industry. This is not simply due to the immaterial nature of software, or to zero marginal cost of replicating software, nor it is due to knowledge intensiveness of the industry. Most software is vertical software and is developed for the purposes of some vertical industry, such as finance or telecom, whose business the software will support. The major challenge for analysing a vertical software industry comes from understanding the interaction of software technology and the business requirements of the vertical industry.
The calculation of shadow prices for industrial wastes using distance functions: An analysis for Spanish ceramic pavements firms
2001
Abstract This paper deals with the calculation of shadow prices for two industrial wastes generated on their production processes by 18 firms belonging to the Spanish ceramic pavements industry. These prices are then used to calculate an extended productivity index which takes into consideration wastes going with the production of marketable goods. We follow the methodological approach first proposed by Fare et al. (The Review of Economics and Statistics 75 (1993)). A negative correlation is found between absolute shadow prices and wastes production intensity, reflecting a greater marginal cost of eliminating wastes for those firms using less contaminant production processes. Differences be…
Tool replacement with adaptive control in a non-stationary non-periodic stochastic process
1991
Abstract The problem of optimum tool replacement is studied in the case in which tool performance is characterized by progressive decay over time following stochastic laws. A control system is assumed which detects, continuously or at fixed intervals, the service state of the tool. Assuming that the service state of the tool affects the marginal cost of production, the latter is used in order to minimize the unit production cost for an unlimited production horizon. The replacement policy proposed is able to update itself in process by means of an iterative procedure which converges to a conditioned optimum. The effectiveness of such a policy is demonstrated analytically, and illustrative ex…
A contribution to the linear programming approach to joint cost allocation: Methodology and application
2009
Abstract The linear programming (LP) approach has been commonly proposed for joint cost allocation purposes. Within a LP framework, the allocation rules are based on a marginal analysis. Unfortunately, the additivity property which is required to completely allocate joint costs fails in presence of capacity, institutional or environmental constraints. In this paper, we first illustrate that the non allocated part can be interpreted as a type of producer’s surplus. Then, by using the information contained in the Simplex tableau we propose an original two-stage methodology based on the marginal costs and the production elasticity of input factors to achieve an additive cost allocation pattern…
Catastrophic risks and the pricing of catastrophe equity put options
2021
In this paper, after a review of the most common financial strategies and products that insurance companies use to hedge catastrophic risks, we study an option pricing model based on processes with jumps where the catastrophic event is captured by a compound Poisson process with negative jumps. Given the importance that catastrophe equity put options (CatEPuts) have in this context, we introduce a pricing approach that provides not only a theoretical contribution whose applicability remains confined to purely numerical examples and experiments, but which can be implemented starting from real data and applied to the evaluation of real CatEPuts. We propose a calibration framework based on his…
Minimising value-at-risk in a portfolio optimisation problem using a multi-objective genetic algorithm
2011
[EN] In this paper, we develop a general framework for market risk optimisation that focuses on VaR. The reason for this choice is the complexity and problems associated with risk return optimisation (non-convex and non-differential objective function). Our purpose is to obtain VaR efficient frontiers using a multi-objective genetic algorithm (GA) and to show the potential utility of the algorithm to obtain efficient portfolios when the risk measure does not allow calculating an optimal solution. Furthermore, we measure differences between VaR efficient frontiers and variance efficient frontiers in VaR-return space and we evaluate out-sample capacity of portfolios on both bullish and bearis…
A GRASP algorithm for constrained two-dimensional non-guillotine cutting problems
2005
This paper presents a greedy randomized adaptive search procedure (GRASP) for the constrained two-dimensional non-guillotine cutting problem, the problem of cutting the rectangular pieces from a large rectangle so as to maximize the value of the pieces cut. We investigate several strategies for the constructive and improvement phases and several choices for critical search parameters. We perform extensive computational experiments with well-known instances previously reported, first to select the best alternatives and then to compare the efficiency of our algorithm with other procedures.
Bayesian forecasting with the Holt–Winters model
2010
Exponential smoothing methods are widely used as forecasting techniques in inventory systems and business planning, where reliable prediction intervals are also required for a large number of series. This paper describes a Bayesian forecasting approach based on the Holt–Winters model, which allows obtaining accurate prediction intervals. We show how to build them incorporating the uncertainty due to the smoothing unknowns using a linear heteroscedastic model. That linear formulation simplifies obtaining the posterior distribution on the unknowns; a random sample from such posterior, which is not analytical, is provided using an acceptance sampling procedure and a Monte Carlo approach gives …