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Managing Strategic Inventories under Investment in Process Improvement Mantin, Benny ; in European Journal of Operational Research (in press) Detailed reference viewed: 73 (0 UL)Joint signature of two or more systems with applications to multistate systems made up of two-state components Marichal, Jean-Luc ; ; et al in European Journal of Operational Research (2017), 263(2), 559-570 The structure signature of a system made up of n components having continuous and i.i.d. lifetimes was defined in the eighties by Samaniego as the n-tuple whose k-th coordinate is the probability that the ... [more ▼] The structure signature of a system made up of n components having continuous and i.i.d. lifetimes was defined in the eighties by Samaniego as the n-tuple whose k-th coordinate is the probability that the k-th component failure causes the system to fail. More recently, a bivariate version of this concept was considered as follows. The joint structure signature of a pair of systems built on a common set of components having continuous and i.i.d. lifetimes is a square matrix of order n whose (k,l)-entry is the probability that the k-th failure causes the first system to fail and the l-th failure causes the second system to fail. This concept was successfully used to derive a signature-based decomposition of the joint reliability of the two systems. In the first part of this paper we provide an explicit formula to compute the joint structure signature of two or more systems and extend this formula to the general non-i.i.d. case, assuming only that the distribution of the component lifetimes has no ties. We also provide and discuss a necessary and sufficient condition on this distribution for the joint reliability of the systems to have a signature-based decomposition. In the second part of this paper we show how our results can be efficiently applied to the investigation of the reliability and signature of multistate systems made up of two-state components. The key observation is that the structure function of such a multistate system can always be additively decomposed into a sum of classical structure functions. Considering a multistate system then reduces to considering simultaneously several two-state systems. [less ▲] Detailed reference viewed: 114 (12 UL)Strategic inventories with quality deterioration Mantin, Benny ; in European Journal of Operational Research (2017), 258(1), 155-164 Detailed reference viewed: 92 (16 UL)A multi-item approach to repairable stocking and expediting in a fluctuating demand environment Arts, Joachim in European Journal of Operational Research (2017), 256(1), 102-115 Detailed reference viewed: 166 (12 UL)Payload-based fleet optimization for rail cars in the chemical industry ; Klosterhalfen, Steffen ; et al in European Journal of Operational Research (2017), 259(1), 113-129 Rail car fleets are significant investments in the chemical industry. Therefore, chemical companies constantly try to optimize the fleets as part of major working capital optimization initiatives. We ... [more ▼] Rail car fleets are significant investments in the chemical industry. Therefore, chemical companies constantly try to optimize the fleets as part of major working capital optimization initiatives. We study a complex rail car fleet optimization problem observed at BASF and an approach to tackle the problem in a sequential way. We develop a mixed integer non-linear programming model to derive suggestions to the questions: (i) How many different rail car sizes in terms of volume are appropriate and what are their optimal volumes? and (ii) For each volume, what is the optimal number of rail cars of this size? The model formulation takes into account various real-world restrictions concerning the volume and weight of the rail cars as well as the tracks that they run on. We propose two solution methods. First, we reformulate the non-linear terms, which results in a mixed integer linear programming (MILP) model. This model can be solved in a reasonable amount of time, if the number of different rail car sizes is small (2 or 3). Second, we develop a two-step approach that uses an enumeration scheme in the first stage to find good initial solutions that are fed into the MILP formulation in the second stage. This approach solves the model for larger numbers of different rail car sizes (4 or 5). Through the fleet redesign BASF has realized cost savings of nearly 2 million euros so far. [less ▲] Detailed reference viewed: 138 (25 UL)Carbon capture and storage and transboundary pollution: A differential game approach Bertinelli, Luisito ; ; Zou, Benteng in European Journal of Operational Research (2014) We study the strategic behavior of two countries facing transboundary CO2 pollution under a differential game setting. In our model, the reduction of CO2 concentration occurs through the carbon capture ... [more ▼] We study the strategic behavior of two countries facing transboundary CO2 pollution under a differential game setting. In our model, the reduction of CO2 concentration occurs through the carbon capture and storage process, rather than through the adoption of cleaner technologies. Furthermore, we first provide the explicit short-run dynamics for this dynamic game with symmetric open-loop and a special Markovian Nash strategy. Then, we compare these strategies at the games’ steady states and along some balanced growth paths. Our results show that if the initial level of CO2 is relatively high, state dependent emissions reductions can lead to higher overall environmental quality, hence, feedback strategy leads to less social waste. [less ▲] Detailed reference viewed: 171 (14 UL)An Integrated Guaranteed- and Stochastic-Service Approach to Inventory Optimization in Supply Chains Klosterhalfen, Steffen ; ; in European Journal of Operational Research (2013), 231 Multi-echelon inventory optimization literature distinguishes stochastic- (SS) and guaranteed-service (GS) approaches as mutually exclusive frameworks. While the GS approach considers flexibility measures ... [more ▼] Multi-echelon inventory optimization literature distinguishes stochastic- (SS) and guaranteed-service (GS) approaches as mutually exclusive frameworks. While the GS approach considers flexibility measures at the stages to deal with stockouts, the SS approach only relies on safety stock. Within a supply chain, flexibility levels might differ between stages rendering them appropriate candidates for one approach or the other. The existing approaches, however, require the selection of a single framework for the entire supply chain instead of a stage-wise choice. We develop an integrated hybrid-service (HS) approach which endogenously determines the overall cost-optimal approach for each stage and computes the required inventory levels. We present a dynamic programming optimization algorithm for serial supply chains that partitions the entire system into subchains of different types. From a numerical study we find that, besides implicitly choosing the better of the two pure frameworks, whose cost differences can be considerable, the HS approach enables additional pipeline and on-hand stock cost savings. We further identify drivers for the preferability of the HS approach. [less ▲] Detailed reference viewed: 56 (1 UL)Analysis of a two-echelon inventory system with two supply modes Arts, Joachim ; in European Journal of Operational Research (2013), 225(2), 263-272 Detailed reference viewed: 43 (0 UL)Weighted Banzhaf power and interaction indexes through weighted approximations of games Marichal, Jean-Luc ; Mathonet, Pierre in European Journal of Operational Research (2011), 211(2), 352-358 The Banzhaf power index was introduced in cooperative game theory to measure the real power of players in a game. The Banzhaf interaction index was then proposed to measure the interaction degree inside ... [more ▼] The Banzhaf power index was introduced in cooperative game theory to measure the real power of players in a game. The Banzhaf interaction index was then proposed to measure the interaction degree inside coalitions of players. It was shown that the power and interaction indexes can be obtained as solutions of a standard least squares approximation problem for pseudo-Boolean functions. Considering certain weighted versions of this approximation problem, we define a class of weighted interaction indexes that generalize the Banzhaf interaction index. We show that these indexes define a subclass of the family of probabilistic interaction indexes and study their most important properties. Finally, we give an interpretation of the Banzhaf and Shapley interaction indexes as centers of mass of this subclass of interaction indexes. [less ▲] Detailed reference viewed: 58 (3 UL)On the dynamics of capital accumulation across space ; Zou, Benteng ; in European Journal of Operational Research (2008), 186(2), 451-465 We solve an optimal growth model in continuous space, continuous and bounded time. The optimizer chooses the optimal trajectories of capital and consumption across space and time by maximizing an ... [more ▼] We solve an optimal growth model in continuous space, continuous and bounded time. The optimizer chooses the optimal trajectories of capital and consumption across space and time by maximizing an objective function with both space and time discounting. We extract the corresponding Pontryagin conditions and prove their sufficiency. We end up with a system of two parabolic differential equations with the corresponding boundary conditions. We propose a simple numerical set-up to simulate PDE systems which we employ to study the roles of initial capital and technology distributions over space in various scenarios. [less ▲] Detailed reference viewed: 101 (3 UL)OR and the management of electronic services - EURO'2004 Bisdorff, Raymond ; ; in European Journal of Operational Research (2008), 187(3), 1293-1295 Detailed reference viewed: 26 (0 UL)Entropy of bi-capacities ; Marichal, Jean-Luc in European Journal of Operational Research (2007), 178(1), 168-184 In the context of multicriteria decision making whose aggregation process is based on the Choquet integral, bi-capacities can be regarded as a natural extension of capacities when the underlying ... [more ▼] In the context of multicriteria decision making whose aggregation process is based on the Choquet integral, bi-capacities can be regarded as a natural extension of capacities when the underlying evaluation scale is bipolar. The notion of entropy, recently generalized to capacities to measure their uniformity, is now extended to bi-capacities. We show that the resulting entropy measure has a very natural interpretation in terms of the Choquet integral and satisfies many natural properties that one would expect from an entropy measure. [less ▲] Detailed reference viewed: 46 (4 UL)k-intolerant capacities and Choquet integrals Marichal, Jean-Luc in European Journal of Operational Research (2007), 177(3), 1453-1468 We define an aggregation function to be (at most) k-intolerant if it is bounded from above by its kth lowest input value. Applying this definition to the discrete Choquet integral and its underlying ... [more ▼] We define an aggregation function to be (at most) k-intolerant if it is bounded from above by its kth lowest input value. Applying this definition to the discrete Choquet integral and its underlying capacity, we introduce the concept of k-intolerant capacities which, when varying k from 1 to n, cover all the possible capacities on n objects. Just as the concepts of k-additive capacities and p-symmetric capacities have been previously introduced essentially to overcome the problem of computational complexity of capacities, k-intolerant capacities are proposed here for the same purpose but also for dealing with intolerant or tolerant behaviors of aggregation. We also introduce axiomatically indices to appraise the extent to which a given capacity is k-intolerant and we apply them on a particular recruiting problem. [less ▲] Detailed reference viewed: 79 (3 UL)Human centered processes: Toward a naturalistic decision making paradigm Bisdorff, Raymond ; ; Marichal, Jean-Luc in European Journal of Operational Research (2007), 177(3), 1313-2118 Detailed reference viewed: 48 (8 UL)Human centered processes: Toward a naturalistic decision making paradigm Bisdorff, Raymond ; in European Journal of Operational Research (2007), 177(3), 1313-1316 Detailed reference viewed: 50 (1 UL)Choices and kernels in bipolar valued digraphs Bisdorff, Raymond ; ; in European Journal of Operational Research (2006), 175(1), 155-170 Detailed reference viewed: 37 (1 UL)Tolerant or intolerant character of interacting criteria in aggregation by the Choquet integral Marichal, Jean-Luc in European Journal of Operational Research (2004), 155(3), 771-791 In many multi-criteria decision-making problems the decision criteria present some interaction whose nature may vary from one situation to another. For example, some criteria may be statistically ... [more ▼] In many multi-criteria decision-making problems the decision criteria present some interaction whose nature may vary from one situation to another. For example, some criteria may be statistically correlated, thus making them somewhat redundant or opposed. Some others may be somewhat substitutive or complementary depending on the behavior of the decision maker. Some others may be decisive in the sense that the global score (of any alternative) obtained by aggregation is bounded by the partial score along one of them. In this paper we analyze this latter form of interaction. When a criterion bounds the global score from above, it is called a blocker or a veto, due to its rather intolerant character. When it bounds the global score from below, it is then called a pusher or a favor. We thus investigate the tolerance of criteria, or equivalently, the tolerance of the weighted aggregation operator (here the Choquet integral) that is used to aggregate criteria. More specifically, we propose (axiomatically) indices to appraise the extent to which each criterion behaves like a veto or a favor in the aggregation by the Choquet integral. Previous to this, we also propose global tolerance degrees measuring the extent to which the Choquet integral is conjunctive or disjunctive. [less ▲] Detailed reference viewed: 53 (2 UL)Entropy of discrete Choquet capacities Marichal, Jean-Luc in European Journal of Operational Research (2002), 137(3), 612-624 We introduce a measure of entropy for any discrete Choquet capacity and we interpret it in the setting of aggregation by the Choquet integral. Detailed reference viewed: 58 (2 UL)Electre-like clustering from a pairwise fuzzy proximity index Bisdorff, Raymond in European Journal of Operational Research (2002), 138(2), 320-331 Detailed reference viewed: 35 (0 UL)Human centered processes and decision support systems ; Bisdorff, Raymond ; in European Journal of Operational Research (2002), 136(2), 233-252 Detailed reference viewed: 42 (0 UL) |
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