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Euro 2013 Abstract Book


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EURO & INFORMS 26th European Conferance on the Operational Research MMXIII ROME 2013, Sapienza Universita Di Roma, Rome-Italy, 01-04 July 2013.

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Euro 2013 Abstract Book

  2. 2. TECHNICAL SESSIONS Monday, 8:30-10:00 MA-02 Monday, 8:30-10:00 O1-2 Discrete Optimal Control, Multi-objective Control of Discrete Processes and Dynamic Positional Games Stream: Discrete Optimal Control Invited session Chair: Gerhard-Wilhelm Weber, Institute of Applied Mathematics, Middle East Technical University, ODTÜ, 06531, Ankara, Turkey, Chair: Vladimir Zubov, Mechanics of continuum media, Institution of Russian Academy of Sciences Dorodnicyn Computing Centre of RAS, Vavilova 40, 119333, Moscow, Russian Federation, 1 - Application of OR to the Control of Metal Crystalliza- tion Process in Casting Alla Albu, Applied Optimization Problems, Institution of Russian Academy of Sciences Dorodnicyn Computing Centre of RAS, Vavilova 40, 119333, Moscow, Russian Federation,, Vladimir Zubov The process of metal crystallization in casting is considered. To ob- tain a model of a good quality it is desirable the shape of solidification front to be close to a plane and its law of motion to be close to a pre- set one. To find a regime of metal solidification that will satisfy the technological requirements the optimal control problem is posed. The speed at which the mold moves is used as the control. The optimal control problem was solved numerically using gradient methods. This work was supported by RFBR N12-01-00572-a and by the Program for Fundamental Research of Presidium of RAS P18. 2 - Determining the solutions for dynamic pozitional games with informational extended strategies. Boris Hancu, Faculty of Mathematics and Informatics, Moldova State University, Mateevici str., 60, MD-2009, Chisinau, Moldova, Moldova, Republic Of, We study the non informational extended games which are generated by the two directional flow informational extended strategies of the players. The theorem about the existence of the Nash equilibrium profiles in this type of the games is proved. The static game with informational extended strategies can be treated as a dynamic game with incomplete information and non informational extended strate- gies, where nature makes the first move, but not everyone observes nature’s move. A parallel algorithm for determining the optimal strate- gies in this dynamic game is elaborated 3 - Investigation of the Fast Automatic Differentiation Technique Vladimir Zubov, Mechanics of continuum media, Institution of Russian Academy of Sciences Dorodnicyn Computing Centre of RAS, Vavilova 40, 119333, Moscow, Russian Federation,, Alla Albu The generalized FAD-methodology allows to obtain the precise value of the functional gradient. However, the discrete conjugate problem may not approximate the continuous conjugate problem, thus the dis- crete gradient wouldn’t approximate the gradient of the continuous problem. The consequence of this can be a convergence to a discrete optimal control, which doesn’t approximate the continuous optimal control. It is proposed to use approximations of the cost functional and differential constraints that will allow to avoid this problem. The work was supported by RFBR N12-01-00572-a. MA-03 Monday, 8:30-10:00 O1-3 Managing service systems Stream: MSOM Service Management SIG Stream Invited session Chair: Jan Van Mieghem, Kellogg School of Management, Northwestern University, 2001 Sheridan Road, Jacobs Center, 5th Floor, 60208, Evanston, IL, United States, 1 - Server Scheduling in Large Overloaded Queueing Systems with Impatient Customers Nahum Shimkin, Electrical Enginnering, Technion, Israel, We consider an overloaded multi-class queueing system with multiple homogeneous servers and impatient customers. Customers of different classes are assigned to servers with the goal of minimizing the wait- ing and reneging costs. For the case of exponential patience and linear waiting costs, a certain index rule (the c-mu/theta rule) is optimal in an asymptotic, fluid-limit sense. In this talk we provide several exten- sions of the asymptotic model, that include non-linear waiting costs, general waiting distributions, and constraints on the waiting times in the different queues. 2 - Does the Past Predict the Future? The Case of Delay Announcements in Service Systems Rouba Ibrahim, University College London, WC1E 6BT, London, United Kingdom,, Mor Armony, Achal Bassamboo We investigate ways of making delay announcements in large service systems, such as call centers. We consider announcing the delay of the last customer to enter service (LES) to delayed customers, upon ar- rival. Customers typically respond to delay announcements by becom- ing more or less patient, and their response alters system performance. We explicitly model announcement-dependent customer behavior. We study the accuracy of the LES announcement in single-class multi- server Markovian queueing models with customer abandonment. We supplement our results with simulation. 3 - Speed Quality Trade-offs in a Dynamic Model Vasiliki Kostami, Management Science & Operations, London Business School, Regent’s Park, NW1 4SA, London, United Kingdom,, Sampath Rajagopalan An important trade-off organizations face is one between quality and speed. Working faster may result in greater output and less delay but may result in lower quality and dissatisfied customers. In this work, we consider dynamic models in a monopoly setting to explore the op- timal balance among the multiple dimensions of speed, price and wait time. The impact of quality is captured via the market demand po- tential which is a function of quality. We obtain several noteworthy results under three scenarios: When only one feature can be changed and when both can be changed. 4 - Collaboration in Service Networks: Architectures and Throughput Jan Van Mieghem, Kellogg School of Management, Northwestern University, 2001 Sheridan Road, Jacobs Center, 5th Floor, 60208, Evanston, IL, United States, Motivated by the trend towards collaboration, we study processing net- works where some activities require the simultaneous collaboration of multiple human resources. Collaboration introduces resource synchro- nization requirements that are not captured in the standard procedure to identify bottlenecks and theoretical capacity. We introduce the notions of collaboration architecture and unavoidable idleness, due to which the theoretical capacity exceeds the maximal achievable throughput or actual capacity. We identify a special class of collaboration architec- tures that have no unavoidable idleness. 2
  3. 3. EURO-INFORMS - Rome 2013 MA-06 MA-04 Monday, 8:30-10:00 O4-4 Complementarity Problems and Variational Inequalities 1 Stream: Mathematical Programming Invited session Chair: Goran Lesaja, Mathematical Sciences, Georgia Southern University, 203 Georgia Ave., 30460-8093, Statesboro, Georgia, United States, 1 - Interior point methods for sufficient LCP in a wide neighborhood of the central path Florian Potra, Mathematics & Statistics, University of Maryland, MD 21250 , Baltimore, United States, We present three interior-point methods for solving sufficient horizon- tal linear complementarity problems using the wide neighborhood of Ai and Zhang. The algorithms do not depend on the handicap of the problem. They are superlinearly convergent and have optimal com- plexity. The first method is Q-quadratically convergent for problem that have a strict complementarity solution. The second order method is Q-superlinearly convergent with Q order 1.5 for general problems, and with Q order 3 for problems that have a strict complementarity solution. 2 - Full NT-Step Faesible Interior-Point Method for the Cartesian P(kappa)-Linear Complementarity Problem over Symmetric Cones Goran Lesaja, Mathematical Sciences, Georgia Southern University, 203 Georgia Ave., 30460-8093, Statesboro, Georgia, United States, A feasible interior-point method (IPM) for the Cartesian P(kappa)- linear complementarity problem over symmetric cones (SCLCP) is presented. The method uses Nesterov-Todd (NT) search directions and full step updates of iterates. With appropriate choice of parameters the algorithm generates a sequence of iterates in the small neighborhood of the central path which implies global convergence of the method and local quadratic convergence of iterates. The iteration complexity of the method matches the currently best known iteration bound for IPMs solving P(kappa)-SCLCP. 3 - Convergence of stochastic average approximations for a class of stochastic optimization problems Bogdan Gavrea, Faculty of Automation and Computer Science, Department of Mathematics, Technical University of Cluj-Napoca, 15 Constantin Daicoviciu Street, 400020, Cluj - Napoca, Romania, We present convergence results of sample average approximations to stochastic optimization problems with mixed expectation and per- scenario constraints. The convergence results are obtained by perform- ing a sensitivity analysis for a mixed nonlinear equations-variational inequality problem. This is a joint work with Mihai Anitescu (ANL). Acknowledgment: The work of B. Gavrea was supported by the Sec- toral Operational Program Human Resources Development 2007-2013 of the Romanian Ministry of Labor, Family and Social Protection un- der the Financial Agreement POSDRU/89/1.5/S/62557. MA-05 Monday, 8:30-10:00 O4-1 Dynamic Programming I Stream: Dynamic Programming Invited session Chair: Lidija Zadnik Stirn, Biotechnical Faculty, University of Ljubljana, Vecna pot 83, 1000, Ljubljana, Slovenia, 1 - Multiobjective and dynamic programming procedure for group decision making in resource management Lidija Zadnik Stirn, Biotechnical Faculty, University of Ljubljana, Vecna pot 83, 1000, Ljubljana, Slovenia, Resource management problems are characterized by multiple and non-commensurable objectives over a long time horizon, by uncer- tainty and participation of different stakeholders and interest groups. Hence, issues related to compromise, negotiation and conflict are cen- tral to this dynamic decision process. This paper describes the pro- cedure in which group AHP method is integrated in a discrete dy- namic programming system. A new method for aggregating individual judgments is proposed and a theorem about acceptable consistency is proved. A numerical example is used to illustrate the procedure. 2 - Stochastic Dual Dynamic Programming and CVaR Applied to Long Term Energy Operation Planning Andre Marcato, Electrical Engineering Department, UFJF, CAMPUS UFJF - Faculdade de Engenharia, Sala 206 - PPEE, 36036-900, Juiz de Fora, MG, Brazil,, Rafael Brandi, Reinaldo Souza, Bruno Dias, Tales Ramos, Ivo Chaves Silva Junior This paper presents the use of CVaR (Conditional Value at Risk) to- gether with Stochastic Dual Dynamic Programming for calculation of hydrothermal dispatch on long term horizon. The Brazilian data base comprising all hydro-thermal system was used for to validate both the CVaR as the risk aversion curve (CAR) methodologies. The CAR methodology has been used for many years in the Brazilian energy operation planning. It will be shown that using the CVaR is more ap- propriate for this problem getting operational scenarios safer. 3 - A Novel Dynamic Programming Approach for Solving the Container Pre-Marshaling Problem Matthias Prandtstetter, Mobility Department, Dynamic Transportation Systems, AIT Austrian Institute of Technology GmbH, Giefinggasse 2, 1210, Vienna, Austria, The Pre-Marshaling Problem (PMP) arises in container terminals where the goal is to find an operation plan with as few container move- ments as possible for pre-ordering containers according to specified priorities such that containers with higher priorities are not blocked by containers with lower ones. We propose a new dynamic programming approach for solving the PMP. Computational experiments emphasize that this is the first exact approach being capable of solving (almost) all benchmark instances of real-world size available in literature to proven optimality within only a few milliseconds. MA-06 Monday, 8:30-10:00 O4-2 Recent Advances in Global Optimization 1 Stream: Global Optimization Invited session Chair: Herman Mawengkang, Mathematics, The University of Sumatera Utara, FMIPA USU, KAMPUS USU, 20155, Medan, Indonesia, Chair: Elise del Rosario, OSSFFI, 14A CyberOne Bldg., Eastwood, Libis, 1110, Quezon City, Metro Manila, Philippines, Chair: Gerhard-Wilhelm Weber, Institute of Applied Mathematics, Middle East Technical University, ODTÜ, 06531, Ankara, Turkey, 1 - Direct search approach for solving non-convex mixed-integer non linear programming problems Hardi Tambunan, Mathematics, Quality University, FMIPA USU, 20155, Medan, North Sumatera Province, Indonesia,, Herman Mawengkang 3
  4. 4. MA-07 EURO-INFORMS - Rome 2013 The mixed integer nonlinear programming problem addressed in this paper has a structure characterized by a subset of variables restricted to assume discrete values, which are linear and separable from the contin- uous variables. The basic idea is to use a strategy of releasing nonbasic variables from their bounds found in the optimal continuous solution in such a way to force the appropriate non-integer basic variables to move to their neighbourhood integer points. Some computational experience are presented. 2 - Stochastic programming model for Land use man- agement problems Siti Rusdiana, Mathematics, University of Syiah Kuala, FMIPA USU, 20155, Medan, North Sumatera Province, Indonesia, Land is used to meet a multiplicity and variety of human needs and to serve numerous, diverse purposes. Our study is focused finding an optimal land/resources portfolio composition through time, in the presence of future market uncertainty. In this paper we formulate a scenario-based stochastic integer programming model, which takes into account the uncertainty related to the market value of revenues ac- cruing from the land in different states In order to take into account the non-constant incremental benefits accruing from different land alloca- tions. 3 - Sampling and integer programming approach for solving water distribution network with reliability consideration Asrin Lubis, Mathematics, Unimed/Graduate School of Mathematics, University of Sumatera Utara, FMIPA USU, 20155, Medan, Sumatra Utara, Indonesia, We propose a nonlinear stochastic optimization model for tackling a WDN under the consideration of reliability in water flows. The non- linearities arise through pressure drop equation. We adopt sampling and integer programming based approch for solving the model. A di- rect search algorithm is used to solve the integer part. 4 - Scrambling index of a class of 2-digraphs Mulyono Mulyono, Mathematics, University Negeri Medan/Grad. School of Math. USU, Fmipa usu, 20155, Medan, Indonesia,, Saib Suwilo A 2-digraph D is a digraph in which each of its arcs is colored by red or blue. The srambling index of 2-digraph D, denoted k(D), is the small- est positive integer s+t over all nonnegative integers s and t such that for each pair of vertices u and v in D there is a vertex w with the prop- erty that there is walks from u to w and from v to w consisting of s red arcs and t blue arcs. We discuss the scrambling index for 2-digraph consisting of two cycles whose lengths differ by 1. MA-07 Monday, 8:30-10:00 O4-3 Vector and Set-Valued Optimization I Stream: Vector and Set-Valued Optimization Invited session Chair: César Gutiérrez, Departamento de Matemática Aplicada, Universidad de Valladolid, E.T.S.I. Informática, Co . Cementerio s/n, Campus Miguel Delibes, 47011, Valladolid, Spain, Chair: Vicente Novo, Matematica Aplicada, Universidad Nacional de Educacion a Distancia, Juan del Rosal no. 12, 28040, Madrid, Spain, 1 - Generating epsilon-optimal solutions in multiobjec- tive optimization by genetic algorithm Marcin Studniarski, Faculty of Mathematics and Computer Science, University of Lodz, ul. S. Banacha 22, 90-238, Lodz, Poland,, El-Desouky Rahmo In [1], some stopping criterion for a genetic algorithm was established, which enables one to find, with a prescribed probability, all minimal solutions in a finite multiobjective optimization problem. In this pa- per, we show how to apply the above-mentioned result to generate epsilon-optimal solutions to some continuous multiobjective optimiza- tion problem. [1] M. Studniarski, Finding all minimal elements of a finite partially ordered set by genetic algorithm with a prescribed probability, Numer- ical Algebra, Control and Optimization 1 (2011), 389-398. 2 - Coercivity, stability, and well-posedness in multiob- jective optimization Ruben Lopez, Departamento de Matematica y Fisica Aplicadas (DMFA), Universidad Catolica de la Santisima Concepcion, Alonso Ribera 2850, 409-0541, Concepcion, VIII Region, Chile, In this talk we show how the notions of coercivity, stability, and well- posedness are related in multiobjective optimization theory. To do this, we employ a recent notion of variational convergence for vector-valued functions. * This work has been supported by Proyecto FONDECYT 1100919 through CONICYT-Chile. 3 - Approximate proper solutions of vector optimization problems. Properties and limit behaviour Lidia Huerga, Applied Mathematics, UNED, C/Juan del Rosal, 12, 28040, Madrid, Spain,, César Gutiérrez, Bienvenido Jiménez, Vicente Novo We present a new notion of approximate proper solution for a con- strained vector optimization problem on a locally convex topological vector space. We study the properties of this type of approximate proper solutions when the error is fixed and also when it tends to zero. In particular, we show that these solutions are useful in order to obtain outer approximations of the efficient set without considering convexity assumptions. 4 - A new concept of solution in vector optimization de- fined via improvement sets César Gutiérrez, Departamento de Matemática Aplicada, Universidad de Valladolid, E.T.S.I. Informática, Co . Cementerio s/n, Campus Miguel Delibes, 47011, Valladolid, Spain,, Bienvenido Jiménez, Vicente Novo In this talk we introduce a new notion of solution for vector optimiza- tion problems based on improvement sets. This notion generalizes the most usual concepts of non-dominated solution for this kind of opti- mization problems. We characterize these solutions by scalarization in convex and non-convex problems. In the first case, the results are obtained by assuming generalized convexity assumptions, and in the second one, they are consequence of characterizing the improvement sets as sublevel sets of nonlinear mappings. MA-11 Monday, 8:30-10:00 G5-3 System Dynamics Modelling and Simulation Session 1 Stream: System Dynamics Modeling and Simulation Invited session Chair: Rogelio Oliva, Mays Business School, 301C Wehner - 4217 TAMU, 77843-4217, College Station, Texas, United States, 1 - Modeling bounded rationality: analysis of the con- sumer choice in the adoption of alternative fuel vehi- cles Laura Ardila, Computer and Decision Science Department, Universidad Nacional de Colombia, Carrera 80 No 65-223, Medellín, Antioquia, Colombia,, Carlos Jaime Franco 4
  5. 5. EURO-INFORMS - Rome 2013 MA-13 This paper presents an approximation to the modeling of bounded ra- tionality (BR) in the adoption of alternative-fuel vehicles in the Colom- bian Market. In order to do this, a simulation model was built. From the results is possible analyze the importance of including BR in the modeling process. The formulated model using BR explains ade- quately the behavior within the system; the model allows a better com- prehension of the consumer decisions, and helps with strategy’s con- struction. The model can be adapted for other economies with similar characteristics to the Colombian market. 2 - Analysis of the mechanism Reliability Charge in the Colombian electricity market: a system dynamic ap- proach Estefany Garcés Arango, Ciencias de la computación y la decisión, Universidad Nacional de Colombia, Colombia,, Carlos Jaime Franco, Isaac Dyner Rezonzew One of the main problems facing liberalized electricity markets is to es- tablish how the generators must be paid to guarantee the investments in new capacity and to ensure the system reliability. Therefore, the mar- ket regulator has decided to implement a security mechanism called Reliability Charge. The results of this new regulation are not obvious, because Colombia has a high dependence on hydro-electric plants. In this paper, we explain a System Dynamic model build for analyzing the effects involving the implementation of this Reliability Charge in the Colombian electricity market. 3 - Three strategic views of organizations. Implications for their dynamics. Bent Erik Bakken, Norwegian Defence University College, St. Georgs vei 4, 0280 OSLO, 0280 OSLO, Norway, Oslo, Norway, A common strategic view of organizations as value chains has been challenged by two complementary value configuration views; value shops and value networks. This paper discusses where each perspec- tive adds value, and the advantages and disadvantages of allowing 1, 2 or 3 configurations to be used in parallel. One system dynamics model portraying each of the three perspectives are provided for a defence or- ganization. Reference modes and sensitivity analysis are provided for each value configuration, and implications for organizational design discussed. 4 - Structural dominance in large and stochastic system dynamics models Rogelio Oliva, Mays Business School, 301C Wehner - 4217 TAMU, 77843-4217, College Station, Texas, United States, Duggan and Oliva (2013) report a significant effort to develop methods for identifying structural dominance in system dynamics models. To date, however, the testing of these methods has been in small (less than 10 stocks) deterministic models that show smooth transitions. While the analysis of simple models is necessary step for proof of concept, the methods have become stable enough to be tested in a wider domain. In this paper we report the findings from expanding the application these methods in two dimensions: increasing model size and incorporating stochastic variance in model variables. MA-12 Monday, 8:30-10:00 G5-4 Facility location Stream: Transportation and Logistics Invited session Chair: Bernard Gendron, DIRO/CIRRELT, Université de Montréal, C.P. 6128, succ. Centre-ville, H3C 3J7, Montréal, Québec, Canada, 1 - Dynamic Facility Location with Generalized Modular Capacities Sanjay Dominik Jena, CIRRELT, Université de Montréal, Canada,, Bernard Gendron, Jean-François Cordeau We introduce a facility location problem with multiple time periods and multiple capacity levels, where the costs for capacity changes are based on a cost matrix. A strong mixed integer programming model is presented that unifies several existing problems found in the literature. We apply our model to three special cases. Computational experiments show that our model can obtain optimal solutions in shorter comput- ing times than the existing specialized formulations. Furthermore, we present a Lagrangean Relaxation heuristic to find good quality solu- tions in even shorter computation times. 2 - A primal heuristic and a Lagrangian relaxation for an industrial two-echelon location-distribution problem Paul-Virak Khuong, DIRO/CIRRELT, Université de Montréal, H3C 3J7, Montreal, Canada,, Bernard Gendron We describe practical methods to solve an industrial location- distribution problem approximately, with solution quality estimates. The problem pertains to the operation of an adaptive multi-echelon distribution system: intermediate locations consolidate flows, and are adjusted in response to changes in demand. A MIP formulation cap- tures the problem’s complex costs, but is very large. We present a multilayer variable neighbourhood search and a Lagrangian decompo- sition method for the same model: the former quickly yields feasible solutions, while the latter proves their quality. 3 - Lagrangian Relaxation Approaches for Multicom- modity Uncapacitated Network Design Enrico Gorgone, DIMES - Dipartimento di Ingegneria Informatica Modellistica Elettronica e Sistemistica, Università della Calabria, Via Bucci, CUBO 41c, VI piano, 87036, Rende, Cosenza, Italy,, Antonio Frangioni, Bernard Gendron We present several algorithms for solving the multicommodity un- capacitated network design problem. We report the results obtained by using different Lagrangian relaxation approaches, a classical spe- cialized dual-ascent method and combinations of these algorithms. We solve the Lagrangian duals by using different variants of non differentiable optimization approaches like (incremental, deflected, projected) subgradient-type methods and (disaggregated, generalized) bundle type methods. 4 - The Impact of Filtering in a Branch-and-Cut Algo- rithm for Multicommodity Capacitated Network De- sign Bernard Gendron, DIRO/CIRRELT, Université de Montréal, C.P. 6128, succ. Centre-ville, H3C 3J7, Montréal, Québec, Canada,, Mervat Chouman, Teodor Gabriel Crainic We study the impact of different filtering methods embedded into a specialized branch-and-cut algorithm for the multicommodity capac- itated network design problem. Contrary to the preprocessing tech- niques used in state-of-the-art MIP solvers, these filtering methods ex- ploit the structure of the problem, while being applicable to a very large class of network design problems. Three types of filtring meth- ods are developed: preprocessing and postprocessing at each node of the tree, as well as domination rules among different nodes of the tree. Computational results will be presented. MA-13 Monday, 8:30-10:00 G5-5 Facility Logistics and Order-Picking in a Warehouse Stream: Facility Logistics Invited session Chair: Pierre Baptiste, de mathématiques et de Génie Industriel, École Polytechnique de Montréal, CP. 6079, succ. centre-ville„ H3C 3A7, Montréal, Québec, Canada, 5
  6. 6. MA-14 EURO-INFORMS - Rome 2013 1 - Ergo-picking: multi-objective approach to consider ergonomics aspects in picking systems design and management Fabio Sgarbossa, Department of Management and Engineering (DTG), Univerity of Padova, 36100, Vicenza, Italy,, Daria Battini, Alessandro Persona One of the most time consuming activities in the logistics, with im- portant energy expenditure, is picking. Traditional optimization ap- proaches considers only time variables. In this paper an innovative multi-objective model has been developed to design picking systems considering also the ergonomics aspect, defined by energy expendi- ture, based on main features of these systems, such as: location, char- acteristics of the piece and handling systems. Several real case studies have allowed the validation using an innovative motion capture system with an integrated ergonomic evaluation tool. 2 - A multi period order picking approach to a multi stage logistic system Rifat Gürcan Özdemir, Industrial Engineering Department, Istanbul Kültür University, Atakoy Campus, Atakoy-Bakirkoy, 34156, Istanbul, Turkey,, Ezgi Nilay Uzun, Nihan Topuk In this paper, a multi period order picking approach to a multi stage lo- gistic system is developed and aimed to determine optimal order pick- ing strategy. The logistic system involves three components as follows: A plant that sends items to the warehouse in which orders are picked and shipped to the customers. The most critical issue for the entire system is planning order picking process in the warehouse efficiently. For this purpose, a mathematical model is developed for minimizing number of pickers subject to lumpy orders received from customers, and dynamic shelf capacities. 3 - Integrated Batching and Routing in Warehouses with Orders and Returns Susanne Wruck, Distribution and Supply Chain Logistics, VU University Amsterdam, De Boelelaan 1105, 1081 HV, Amsterdam, Netherlands, We present an iterated local search approach for the simultaneous op- timization of order batching and order picker routing in warehouses. Thereby we incorporate deadlines of customer orders and schedule a working shift for multiple order pickers simultaneously. Further- more, we incorporate the restoring of potential product returns during the picking tours. We demonstrate that significant cost savings can be achieved by the integration of order and return processing and that joint batch and route optimization can lead to better order picking per- formance. 4 - Multiple doors cross docks scheduling Pierre Baptiste, de mathématiques et de Génie Industriel, École Polytechnique de Montréal, CP. 6079, succ. centre-ville„ H3C 3A7, Montréal, Québec, Canada,, Mohammad yousef Maknoon Material handling inside cross dock plays a critical role. To have efficient handling plan, transferring decisions should be simultane- ously considered with the trucks processing order, incoming and out- going.We present a mathematical model of the material handling in a cross dock with multiple doors (optimal solution up to 6 doors, 20 trucks with Cplex) and an heuristic for bigger size problems. Numer- ical results depict the stability of this heuristic and compare both ap- proaches. Finally, we investigate various loading scenarios and provide some recommendations on material handling decisions. MA-14 Monday, 8:30-10:00 G5-6 Metaheuristics Stream: Metaheuristics Invited session Chair: Alok Choudhary, Management School, University of Sheffield, IWP Building, Mushroom Lane, S10 2TN, Sheffield, United Kingdom, 1 - GRASP and Path Relinking based on structured so- lution clustering Arne Løkketangen, Molde University College, Britveien 2, 6411, Molde, Norway,, Jianyong Jin Solution clustering based on structural similarity is a novel way to par- tition elite solutions found during a search. The structural information captured provides superior guidance for later intensification phases. We explore different structurally based solution distance measures, as well as novel variants of GRASP and Path Relinking based on utiliz- ing information from structured solution clustering. Both in-cluster and between-cluster guidance is investigated. The methods are tested on large benchmark VRPs from the literature. 2 - Optimization of microchannels for liquid cooling of electronic chips Tuba Okutucu, Mechanical Engineering, Middle East Technical University, Makina Mühendisli˘gi Bölümü, A-143, ODTU, 06800, Ankara, Turkey,, GÖker TÜrkakar Dimensional optimization of silicon microchannel heat sinks is per- formed by minimizing the total thermal resistance. Intel Core i7-900 Desktop Processor is considered as the reference chip to be cooled. The study is unique in that the optimization has been performed for localized multiple heat sources. The results of the optimization agreed very well with available ones in the literature. Grid search is utilized to obtain the minimum value of the objective function. The optimization procedure may be improved using a meta-heuristic algorithm such as Tabu search. 3 - Progressive multi-objective optimization Kenneth Sörensen, Faculty of Applied Economics, University of Antwerp, Prinsstraat 13, 2000, Antwerpen, Belgium,, Johan Springael PMOO is a novel technique that includes the decision maker’s prefer- ences into the multi-objective optimization process instead of tackling these steps sequentially. In this talk, we present a PMOO method for the multi-objective knapsack problem. This approach integrates the well-known PROMETHEE multi-criteria method into a simple tabu search method. 4 - A carbon-footprint optimization model for integrated forward-reverse logistics Alok Choudhary, Management School, University of Sheffield, IWP Building, Mushroom Lane, S10 2TN, Sheffield, United Kingdom, This research proposed a MILP optimization model for forward- reverse logistics with carbon-footprint considerations. This research extends the traditional model by both minimizing cost and carbon foot- print across the supply chain and incorporates carbon emission param- eters with various operational decision-making variables related to fa- cility layout decisions, procurement and production. We provide a se- ries of insights that highlight the impact of operational decisions on carbon emissions. An efficient forest data structure algorithm is used to solve the optimization problem. MA-15 Monday, 8:30-10:00 G5-2 Genetic Algorithms and Genetic Programming Stream: Metaheuristics (contributed) Contributed session Chair: Derya Dengi, Department Industrial Engineering, Yasar University, Yasar University Selcuk Yasar Kampusu No:35-37, Agacliyol Bornova, 35100, Izmir, Izmir, Turkey, 6
  7. 7. EURO-INFORMS - Rome 2013 MA-17 1 - Comparative Analysis of Differential Evolution, Fire- fly and Genetic Algorithms on Dynamic Environ- ments Burcin Ozsoydan, Industrial Engineering, Dokuz Eylul University, Turkey,, Adil Baykaso˘glu Most of the real-life problems require a dynamic optimization aris- ing from the uncertainty of future events, which makes optimization harder. Genetic Algorithms (GA) and Differential Evolution (DE) have been widely used for static optimization. Their applications to dynamic optimization problems are rare. In the present work an improved Fire- fly Algorithm (FA) is presented for dynamic optimization along with comparisons via GA and DE. Results demonstrate that, the proposed FA significantly achieves superior results for both stationary and dy- namic problems in comparison to GA and DE. 2 - Optimizing intrusion detection system performance in ubiquitous environments using genetic algorithm approach Lynda Sellami, computer science, University of Bejaia, route de targua ouzemou, 06000, Bejaia, Algeria, The objective of ubiquitous computing is to give the users the ability to communicate and provide information regardless of their location in the Internet network, The success of these distributed computing depends largely on a strong security mechanism such as intrusion de- tection. This article presents a review to understand, examine, and cri- tique the current state of its applications in various fields and proposing a solution to this problem by using genetic algorithm approach. 3 - Internet decision system for combinatorial optimiza- tion problems under permutation Lamia Trabelsi, Laboratoire ROI Ecole Polytechnique, Tunisia,, Talel Ladhari In this work, we propose a web-based decision support system to solve combinatorial optimization problems under permutation (COPP) using genetic programming. The REST (Representational State Transfer) ar- chitecture style is used to allow the new system to communicate with researcher applications over the net. REST avoids inter-operability problem. It allows accessing resources by URI (Universal Resource Identifier). Via the URI, researchers are able to reuse or to evaluate at run-time their operators with the available operators. 4 - A Genetic Algorithm Based Approach for Opera- tor Allocation Problem in Garment Industry with the Consideration of Labour Skill Levels Derya Dengi, Department Industrial Engineering, Yasar University, Yasar University Selcuk Yasar Kampusu No:35-37, Agacliyol Bornova, 35100, Izmir, Izmir, Turkey,, Gonca Tuncel Sewing lines in garment industry are complicated assembly lines due to the labour intensive work nature with great number of operations, various types of machines, and different labour skill levels. In this study, we considered operator allocation problem in an international garment factory. Labour skill levels in each of the operation are also taken into account to improve the workload balance. The problem is solved by using a genetic algorithm based approach. The experimental results for different product models are presented and discussed. MA-16 Monday, 8:30-10:00 G5-7 Network Flows I Stream: Routing Problems Invited session Chair: Paola Festa, Dept. of Mathematics and Applications, University of Napoli Federico II, Compl. MSA - Via Cintia, 80126, Napoli, Italy, Chair: Francesca Guerriero, D.E.I.S.: Department of Electronics, Computer Science and Systems, University of Calabria, Via P. Bucci, 87036, Rende, Italy, 1 - Solving the Shortest Path Tour Problem and Some of Its Variants Paola Festa, Dept. of Mathematics and Applications, University of Napoli Federico II, Compl. MSA - Via Cintia, 80126, Napoli, Italy,, Daniele Ferone, Francesca Guerriero, Demetrio Laganà The shortest path tour problem consists of finding in a weighted di- graph a shortest path from a given origin node to a given destination node, crossing a sequence of disjoint and possibly different-sized node subsets, given in a fixed order. In this talk, a polynomial-time reduc- tion of the problem to a classical shortest path problem over a modified digraph is illustrated. Several exact solution methods are proposed and their performances are compared with the state-of the-art solving pro- cedure. Some variants of the problem and their properties are analyzed. 2 - Maximizing the propagation of the advertisements in social networks Ciriaco D’Ambrosio, Department of Computer Science, University of Salerno, Italy,, Francesco Carrabs, Raffaele Cerulli We study the problem of maximizing the propagation of an advertise- ment in a social network where a node represents a user and an edge represents the friendship relation. The problem is to identifying a set of nodes in which to publish an advertisement in order to maximize its propagation without wasting ad spaces. Moreover, we analyze an- other problem where the aim is to maximize the number of selected nodes ensuring a fixed propagation level. Two formulations and a metaheuristic approach are presented. 3 - Fast Shortest Path Queries in Road Networks Leonid Antsfeld, NICTA, 223 Anzac Pde., NICTA, Level 4, Reception, 2052, Kensington, NSW, Australia,, Philip Kilby, Andrew Verden, Toby Walsh Our new algorithm, identifies key nodes in a road network. Initially, we identify all major nodes, i.e., nodes which have at least one end- point as a highway. Next, we divide our map to clusters. Then for every cluster, we identify the furthest major node, such that there is no other major node on a shortest path from this cluster. The set of access nodes of a cluster is defined as a hitting set of all major nodes which are on a shortest paths originating from the convex hull of the cluster. On average a cluster has 5 access nodes, therefore the query translates to just a few table lookups. 4 - Network interdiction by dynamic interdictor using shortest path Ahmet Kabarcik, Industrial Engineering, Cankaya University, Eskisehir Yolu, Yenimahalle, 06810, Ankara, Turkey,, Levent Kandiller, Haluk Aygunes This study considers a network interdiction problem in which arcs are disabled by a dynamic interdictor. Its assumed that the network is com- posed of two interconnected networks. One of the networks is used by the user and the other one is used by the interdictor. An interdictor’s node may either be deployed on an arc or on a node of the network user. Nodes on the interdictor’s network are candidate points for de- struction. Here, it’s aimed to find the shortest path that can be used by the interdictor while destroying all paths between origin and destina- tion nodes of network user. MA-17 Monday, 8:30-10:00 G5-8 Green Vehicle Routing Stream: Sustainable Transport Planning Invited session Chair: Esben Linde, DTU Transport, Technical University of Denmark, Bygning 115, Bygningstorvet, 2800, Kgs. Lyngby, Denmark, 7
  8. 8. MA-19 EURO-INFORMS - Rome 2013 1 - Environmental Vehicle Routing Problem (VRP) Georgios K.D. Saharidis, Mechanical Engineering, University of Thessaly, Pedion Areos, 38334, Volos, Thessaly, Greece,, George Liberopoulos The vehicle is a very important component for the evaluation and es- timation of environmental externalities in the transport sector. How- ever, there is another important component that affects the amount of emissions that has been taken either partially or not at all under consid- eration. This component is related to the characteristics of the trans- portation network (TN). In this research, we develop a novel objective function for the environmental VRP that takes as input several data and estimates the Environmental Externalities Score (EES) of a route. 2 - Demand Management and Vehicle Routing in E- fulfilment Richard Eglese, The Management School, Lancaster University, Department of Management Science, LA1 4YX, Lancaster, Lancashire, United Kingdom,, Xinan Yang, Arne Karsten Strauss, Christine Currie For many customers, ordering goods over the internet for home deliv- ery offers a more sustainable way of shopping than making a special trip by car to a retail outlet. However attended home delivery services face the challenge of providing narrow delivery time slots to ensure customer satisfaction, whilst keeping the delivery cost under control. Dynamic pricing policies based on a customer choice model are pro- posed to determine how much incentive (discount or charge) to offer for which time slot. A simulation study based on real data shows the effectiveness of the approach. 3 - An Algorithm for Sustainable Vehicle Routing Fernando Oliveira, Operations MAnagement, ESSEC Business School, Cergy, France,, Anne Liret The vehicle routing problem is known for being NP-hard. In this ar- ticle we analyze this problem from a perspective of a company that wants to introduce vehicle sharing in an attempt to increase efficiency and reduce CO2 emissions. We provide a formulation of the problem considering multiple depots and time windows. We propose an algo- rithm to approximate the solution is a real-case study and analyze its main properties. 4 - Routing of Electric Vehicles: City Distribution in Copenhagen Esben Linde, DTU Transport, Technical University of Denmark, Bygning 115, Bygningstorvet, 2800, Kgs. Lyngby, Denmark,, Allan Larsen, Anders Vedsted Noerrelund, Stefan Ropke, Min Wen In this work, a Vehicle Routing Problem with Time Windows consid- ering EV constraints of limited driving range and freight capacity is addressed (EVRPTW). The EVs are allowed to recharge at certain lo- cations, and aspects of intelligent location of these recharging points are considered. The objective is to find the least cost plan for EV rout- ing and compare this to conventional routing. A heuristic method is developed and tested on data based on real-life collected data on distri- bution vehicles in central Copenhagen, Denmark. The EVRPTW has so far received little attention in the literature. MA-19 Monday, 8:30-10:00 G5-10 Advanced Inventory Control in SCM Stream: Business Excellence in Logistics Invited session Chair: Sebastian Langton, Logistics Management Department, Helmut-Schmidt-University, 22041, Hamburg, Germany, Chair: Johannes Siebert, Business Administration, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Bayern, Germany, 1 - Inventory optimization for a recoverable manufactur- ing system with product substitution Semra Sebnem Ahiska, Industrial Engineering Department, Galatasaray University, Ciragan Cad. No:36 Ortakoy, 34349, Istanbul, Turkey,, Emre Kurtul, Rusty King The periodic-review inventory control problem for a stochastic manu- facturing/remanufacturing system with product substitution is studied. A remanufactured item has a lower selling price than a manufactured (i.e., new) item, thus separate demand streams exist for those products. A product substitution strategy is considered where the demand for a remanufactured item is satisfied by a new item if no remanufactured item is left in stock and new item inventory is available. Through a Markov decision analysis, we find the optimal inventory policies, and determine the value of product substitution. 2 - Decision Making under Bounded Rationality Terms: Application in a Transportation Problem Maria Giannopoulou, Industrial Management & Technology, University of Piraeus, Department of Industrial Management & Technology University of Piraeus — 18534 Piraeus, GREECE, 18534, Piraeus, Greece,, Dimitrios Emiris Decision makers operate under cognitive, emotional and computa- tional constraints in unstable and complicated environments. The Bounded Rationality (BR) theory takes into account such constraints and weaknesses to provide a more realistic decision making frame- work. This work presents a Fuzzy Cognitive Map (FCM) for a simu- lation problem of strategy optimization in transportation contracts sold by e-auctions. The model inputs are concepts concerning BR elements affecting bidders’ behavior and generates data concerning the interac- tions between these concepts and potential correlations among them. 3 - A Two-Loop Machine Learning Approach for Evaluat- ing Supply Chain Stockout Events Sebastian Langton, Logistics Management Department, Helmut-Schmidt-University, 22041, Hamburg, Germany,, Johannes Siebert, Martin Josef Geiger Despite the relevance of stockout cost parameters in many logistics models, a need for practicable cost quantification methods can still be stated. As a methodologically new idea we present an interac- tive machine learning approach for estimating such costs. Previous experiments revealed that the consistency of data from the decision maker (DM) is essential for satisfying machine learning results. In line with this, we introduce an idea of inconsistent data elimination by re-integrating the DM in a second learning loop. The talk completes with presenting experimental work and numerical results. MA-20 Monday, 8:30-10:00 G5-11 Routing in Public Transport Networks Stream: Optimization in Public Transport Invited session Chair: Gianpaolo Oriolo, Universita’ Roma Tor Vergata, Italy, Chair: Giuseppe Italiano, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", via del Politecnico 1, 00133, Rome, Italy, 1 - Stochastic Route Planning in Public Transport Alpár Jüttner, IBM-ELTE Center for Applied Mathematics, Dept of Operations Research, ELTE, Pázmány P. sétány, 1/C, H-1117, Budapest, Hungary,, Kristof Berczi, Mátyás Korom, Jacint Szabo, Tim Nonner, Marco Laumanns There are plenty of public transport planners that help passangers to find a route satisfying their needs. However, a common weakness 8
  9. 9. EURO-INFORMS - Rome 2013 MA-22 of these methods that they assume a deterministic environment. Ve- hicles in public transport are typically behind or before time, hence making the availability of a given journey in real life questionable. We present an algorithm that overcomes this uncertainty by using a stochastic model for departure and travel times. The output of the al- gorithm is not a single route but a policy for each node that defines which services to take at a given time. 2 - Stochastic on-time arrival problem on public trans- portation networks Sebastien Blandin, IBM Research Collaboratory – Singapore, IBM Singapore Pte Ltd, 9 Changi Business Park Central, The IBM Place, 486048, Singapore, Singapore, Singapore,, Samitha Samaranayake, Alex Bayen We formulate the stochastic on-time arrival problem on public trans- portation networks. Link travel times are estimated according to a route-based headway diffusion model, which allows the computation of associated waiting times at connection nodes. We prove that this for- mulation leads to efficient computations tractable for large networks, even in the case of time-varying headway distributions. Additionally, robustness to recurrent variability as well as unexpected events is very naturally represented under this formulation. Algorithm performance is illustrated using realistic transit data. 3 - When Algorithms Come True: A Dynamic Multimodal Route Planner for Rome Luca Allulli, Centrale della Mobilità, Roma servizi per la mobilità srl, Piazzale degli Archivi, 40, 00144, Rome, Italy, "Roma servizi per la mobilità" is the municipal agency for public and private transport in Rome. The agency recently developed a dynamic multimodal route planner ( Real-time data is col- lected from GPS bus trackers, which cover the vast majority of buses in Rome. We present the main challenges our small development team had to face: creating a simple, yet flexible framework for dynamic multimodal routing, which allows us to rapidly prototype and integrate diverse means of transport; dealing with raw data from bus trackers; and tuning code to obtain adequate performance. 4 - Real-Time Public Transportation Route Planners Federico Santaroni, Department of Civil Engineering and Computer Science Engineering, Tor Vergata, Via Politecnico 1, 00133 , Roma, Italy,, Luigi Laura, Federico Cosentino, Emanuele Paracone In the last years we have seen a huge contribution to routing algorithms in large transportation networks, especially focusing on road networks. Despite many results in this direction, if we switch our attention to public transportation networks, this is a completely different scenario in which one cannot directly apply the same algorithmic techniques. In this talk we will discuss the challenges arising in designing a pub- lic transportation route-planner, in particular in the case where one can use data provided by the GPS vehicles’ devices in real time. MA-21 Monday, 8:30-10:00 G6-1 Scheduling Approaches for Complex Manufacturing and Service Systems Stream: Scheduling Invited session Chair: Lars Moench, FernUniversität in Hagen, 58097, Hagen, Germany, 1 - A Reinforcement Learning Approach to Solving Hy- brid Flexible Flowline Scheduling Problems Dmitry Borodin, Optimization, OM Partners, Koralenhoeve 23, 9000, Wommelgem (Antwerp), Belgium,, Bert Van Vreckem, Ann Nowe, Kris Dockx, Wim De Bruyn This research presents a technique based on Learning Automata (LA) to solve Hybrid Flexible Flowline Scheduling Problems with addi- tional constraints like sequence dependent setup times, precedence re- lations between jobs and machine eligibility that occur in complex real- life problems like those in process industry. In the proposed method, LA play a dispersion game to determine the order of jobs to be pro- cessed so that makespan is minimized while avoiding illegal permuta- tions. Computational results on benchmark problems indicate that LA can yield better results than the ones known until now. 2 - Missing operations in reentrant flow-shop problems Richard Hinze, TU Dresden, Germany,, Dirk Sackmann, Udo Buscher, Gerhard Aust We propose a model for the reentrant flow-shop scheduling in order to minimize makespan. Reentrant flow shop scheduling problems occur in practical applications, such as the manufacturing of semiconduc- tors, airplane engines, and petrochemical production. The formulation considers missing operations. Compared to traditional formulations the values of makespan are significantly reduced, due to an appropri- ate dealing with processing times equal to zero. Computational tests with different problem sizes reveal that computation times are mainly influenced by the total number of jobs. 3 - A new method for the evaluation of a neighbor so- lution in local search procedures for solving the JSPTWT Jens Kuhpfahl, School of Economics and Business, Chair of Production and Logistics, MLU Halle-Wittenberg, Germany,, Christian Bierwirth Efficient local search in job shop scheduling requires estimating the success of possible neighborhood moves. Typically, a lower bound is calculated for a new schedule by estimating heads and tails of the op- erations affected by the neighborhood search operator. In this talk we show how this technique can be improved for the JSPTWT regarding reliability and computation time. It allows us to determine the true ob- jective function value of the neighbor solution instead of just verifying a necessary condition for descent moves in the local search. 4 - An Instance Generator for Scheduling Problems with Alternative Process Plans Oleh Sobeyko, University of Hagen, 58097, Hagen, Germany,, Roman Capek, Zdenek Hanzalek, Lars Moench We consider scheduling problems with alternative process plans. A new generator for problem instances is proposed. The generator is designed for both resource constrained project scheduling problems and problems based on the integrated process planning and schedul- ing model while the data representation for both classes of problems is unified. We propose a common model for scheduling problems with alternatives and fill the gap in existing tools for generating problem instances. Structural properties, the resource environment, and the at- tributes of activities are defined as input parameters. MA-22 Monday, 8:30-10:00 G6-2 Scheduling & Project Management Stream: Scheduling, Time Tabling & Project Manage- ment (contributed) Contributed session Chair: Ching Chih Tseng, Business Administration, Dayeh University, 168 University Rd., Dacun, Taiwan, R.O.C., 51591, Changhua, Taiwan, 1 - A heuristic approach for profit oriented disassembly sheduling problem Melike Kaya Akça, METU-Industrial Engineering Dept., Graduate School of Natural and Applied Sciences, Turkey,, Z. Pelin Bayindir, Ferda Can Cetinkaya 9
  10. 10. MA-23 EURO-INFORMS - Rome 2013 We consider a disassembly scheduling problem for multiple products with parts commonality and ample supply of discarded products. We propose a heuristic algorithm which is based on the idea of sequentially solving a relaxed version of the problem and single-period integer pro- gramming models. In a computational study, the performance of the heuristic approach is assessed. The results of the computational exper- iments indicate that the heuristic algorithm solves the problems in a reasonable computational time and generates near optimal solutions. 2 - On an algorithm of multicriteria scheduling problem Ketevan Kutkhashvili, Mathematics, University of Georgia, 77 Kostava Street, 0102, Tbilisi, Georgia,, Liana Qaralashvili On the basis of general theory methods mathematical model is con- structed for such scheduling theory problems for which tasks imple- mentation is possible by single-step multiprocessing system in which processors are half interchangeable and additional resources and sets of partial order are empty. The new multicriteria optimization algo- rithm (from the viewpoint of speed of acting and other certain criteria) is constructed. 3 - A bayesian approach to preventive maintenance op- timization in unreliable systems Dincer Goksuluk, Biostatistics, Hacettepe University, Sıhhiye Campus, Faculty of Medicine, Department of Biostatistics, Ankara - TURKEY, 06590, Ankara, Turkey,, Selma Gürler, Deniz Türsel Eliiyi In this study, we present a sequential preventive maintenance (PM) model for a component subject to failure. We assume an age reduc- tion model for imperfect PMs, performed whenever the component’s reliability falls below the threshold level, R. We consider the problem under lack of data where Bayesian methods are more appropriate than the frequentist view. We model the total expected cost over all cy- cles, and the optimal preventive maintenance plan until replacement is found dependent on the threshold value. A numerical study is also conducted for sensitivity analysis of the developed model. 4 - Minimizing the total weighted completion time for time-dependent jobs Krzysztof Ocetkiewicz, Department of Algorithms and System Modelling, Gdansk University of Technology, 11/12 Gabriela Narutowicza Street, 80-233, Gda´nsk, Poland,, Marek Kubale We consider a single machine time-dependent scheduling problem with linear deterioration and Sum wiCi objective. We present a branch-and-bound algorithm improved by elimination of dominated partial schedules. Such an algorithm makes possible to deal with huge memory requirements of the elimination while retaining running time speedup. Also,it is capable of finding all Pareto optimal solutions sub- ject to Sum wiCi and Cmax criteria and scheduling jobs with prece- dence constraints. Our algorithm allows to double the size of instances that can be solved to optimality in a reasonable time. MA-23 Monday, 8:30-10:00 G6-3 Realistic Production Scheduling Stream: Realistic Production Scheduling Invited session Chair: Cyrus Siganporia, Biochemical Engineering, University College London, United Kingdom, 1 - New lower bounds for minimising the total comple- tion time in a two-machine non permutation flowshop scheduling problem Sabrine Chalghoumi, Economie, Ecole supérieure des sciences économiques et commerciales de Tunis, 4, Rue Abou Zakaria El Hafsi, 1089 Montfleury, Tunis, Tunisia,, Mrad Mahdi, Talel Ladhari The presented work addresses the two-machine non-permutation flow shop scheduling problem with the objective of minimizing the total completion time subject to release dates. We proposed two new mixed integer linear programming formulations. The first proposed MILP formulation is based on the Completion Time Variable formulation while the second one is based on a time indexed formulation. More- over, two new derived lower bounds are obtained by linear relaxation technique. Our computational experiments provide evidence that these new lower bounds present interesting and significant results. 2 - Solution Approaches For Flexible Job Shop Schedul- ing Problems Serife Aytug Balci, Industrial Engineering, Graduate School of Natural and Applied Sciences, Ankara, Turkey,, Meral Azizoglu, Cemal Oguzsoy In this study, we consider FJSP existing in discrete parts manufactur- ing industries. We are motivated by the production environment of a company, operating at Turkish defense industry. Our objective is to minimize the total weighted completion times of the jobs in the sys- tem. We formulate the problem as a mixed integer linear program and find that our model could find optimal solutions only to small sized problem instances. For medium and large sized problem instances, we develop heuristic algorithms with high quality approximate solutions in reasonable solution time. 3 - A genetic algorithm for flexible job shop scheduling with overlapping in operations Yunus Demir, Industrial Engineering, Ataturk University, Erzurum Turkey, 25240, Erzurum, Outside US, Turkey,, Selçuk Kür¸sat ˙I¸sleyen Flexible job shop scheduling problem (FJSP) is extension of job shop scheduling problem (JSP) which allows an operation to be performed by any machine among a set of available machines. In this paper we handled FJSP with overlapping in operations. To solve this problem a genetic algorithm (GA) is proposed. The proposed algorithm was tested on benchmark problems taken from literature of different scales. Obtained results were compared with the results obtained by other al- gorithms. 4 - Multi-objective optimisation of biopharmaceutical production plans using a state task network repre- sentation Cyrus Siganporia, Biochemical Engineering, University College London, United Kingdom,, Lazaros Papageorgiou, Suzanne Farid Biotech firms face mounting pressure to meet demands for multiple commercial therapeutics whilst minimising costs. Obtaining optimal capacity plans across multiple sites is complicated by conflicting ob- jectives and products with batch and semi-continuous modes of pro- duction. This presentation describes development of a multi-objective STN MILP model to help decide whether to outsource manufacturing, build a new facility, or do both as capacity limits are reached. An in- dustrial case study is presented showing how better long-term capacity plans can be generated when including various criteria. MA-24 Monday, 8:30-10:00 G6-4 Airport Operations Management Stream: Project Management and Scheduling Invited session Chair: Jeroen Belien, Center for Informatics, Modeling and Simulation, Hogeschool-Universiteit Brussel, Warmoesberg 26, 1000, Brussels, Belgium, 10
  11. 11. EURO-INFORMS - Rome 2013 MA-26 1 - A rolling horizon framework for an aircraft line main- tenance problem Jorne Van den Bergh, HUBrussel, Belgium,, Jeroen Belien, Liesje De Boeck, Erik Demeulemeester We present a rolling horizon framework for an aircraft line mainte- nance scheduling problem. The procedure starts with the creation of a "robust’ base schedule in order to deal with the stochasticity in the release times of the jobs. In the rolling horizon procedure, flight de- lays are simulated and we check whether the base schedule can handle these delays with the available capacity and/or time buffers or whether the base schedule needs to be adjusted. When rescheduling is needed, we search for the cheapest solution that results in the smallest number of changes to the base schedule. 2 - Flight and Crew Rescheduling in Post Perturbation Situation Peiman Alipour Sarvari, Industril engineering, Gazi University, Yunus Emre ogrenci yurdu, Altindag-Ulus, 06500, Ankara, Select, Turkey, Abstract- Airline operations are disrupted frequently. The most impor- tant factors are unstable weather conditions and unpredictable techni- cal aeronautics problems. In a disrupted situation, an airline operator needs to quickly adjust the timetable and the resource schedules so the importance of re-assignment of facilities to flight is much more clearer. In this study, we considered the re-assignment of aircraft to flight after the emergence of disorder in the initial planning with regard to crew scheduling constraints. We propose a problem formulation and a heuristic solution algorithm. 3 - Aircraft Maintenance Scheduling and Optimization for Summer Period: A Case for Turkish Airlines Yavuz Ozdemir, Industrial Engineering, Yildiz Technical University, Yildiz Teknik Universitesi Endustri Muhendisligi Bolumu Barbaros Bulvari, Yildiz/Besiktas/Istanbul TURKEY, Istanbul, Turkey, Turkey,, Ahmet Bolat, Merve Karaca Decreased ticket prices in airline transportation make a competitive airline market, and forces airline companies to make professional de- cisions for their activities. In this study, C type maintenance, which is one of the important and long lasting maintenance, is assigned for summer period considering the capacity of hangar with Microsoft Vi- sual Basic. Maximizing the utilization and minimizing the number or required aircrafts are considered as our aims. According to dynamic frame of airline operations and daily irregularities, manual editing is allowed in the code that studied in this paper. MA-25 Monday, 8:30-10:00 G9-1 Retail models Stream: INFORMS MSOM Stream Invited session Chair: Esra Cinar, Operations Management, IESE Business School, Cr. Arnús i Garí 3-7, 08034, Barcelona, Spain, 1 - A closed-loop approach to dynamic assortment plan- ning Esra Cinar, Operations Management, IESE Business School, Cr. Arnús i Garí 3-7, 08034, Barcelona, Spain,, Victor Martínez de Albéniz Firms offering short-lived products are constantly trying to keep the customers interested by refreshing their assortments, for example in fashion retailing. We model these dynamics by assuming that products lose their attractiveness over time and we let the firm enhance the as- sortment at a cost, e.g., with new product introductions. We character- ize the optimal closed-loop policy that maximizes the revenue obtained by increasing the attractiveness of an assortment, minus the associated cost of the adjustments. Interestingly, we find that an assort-up-to pol- icy is optimal in some cases. 2 - Optimal Assortment Planning for Retailers Using Transshipments Nagihan Comez, Faculty of Business Administration, Bilkent University, Bilkent University Isletme Fakultesi MAZ 20, Bilkent, 06800, Ankara, -, Turkey,, Alper Sen, Hilal Dag Transshipments among retailers may help to recover stock-outs timely and economically. In this study, our objective is to find the optimal assortments in a centralized retailer system, where retailers can utilize transshipments for the products they don’t keep. Using an exogenous demand model, we show that when all possible products can be ranked according to certain popularity criteria, the products in both the to- tal and common assortments of retailers will be chosen following this popularity list at the optimality. We also show the benefits of trans- shipments wrt a no-transshipment system. 3 - Assortment Competition with Information Revelation Victor Martínez de Albéniz, IESE Business School, Barcelona, Spain,, Gurhan Kok In industries where customer needs quickly change, retailers can post- pone their assortment decisions (amount of variety, balance across categories) if they are quick enough. We study here how assortment competition depends on the postponement capabilities of retailers. We develop a stylized model where two retailers choose their assortment breadth either before or after market characteristics are revealed. MA-26 Monday, 8:30-10:00 G9-7 Combinatorial Optimization: Applications Stream: Combinatorial Optimization I Invited session Chair: Jan van Vuuren, Department of Logistics, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, Western Cape, South Africa, 1 - Choosing fuel treatment sites to reduce risk of fire John Hearne, Mathematical and Geospatial Sciences, RMIT University, GPO Box 2476v, 3001, Melbourne, Victoria, Australia,, James Minas Reducing fuel loads is a method for reducing the risk of wildfires. Planning for this requires decisions relating to location, extent, and timing of treatment. We formulate MIP problems to deal with this at the landscape-level in the presence of resource limitations. We gener- ate a number of fuel treatment patterns and landscape metrics with a view to modifying the behaviour and effects of large wildfires. Meth- ods for incorporation of a range of ecological, operational and cost constraints are also considered. 2 - An exact dynamic programming algorithm for the air- craft sequencing problem Martin Kidd, Dipartimento di Elettronica, Informatica e Sistemistica (DEIS), University of Bologna, Bologna, Italy,, Fabio Furini, Carlo Alfredo Persiani, Paolo Toth We consider the static case of the aircraft sequencing problem on a sin- gle runway with constraints on the deviation from the first-come-first- serve order. An exact dynamic programming algorithm is proposed, and the effects of limiting the states in the state space graph are inves- tigated. Completion bounds are computed and are used together with heuristic upper bounds to further limit the number of states. For real world air traffic instances from Milan Linate Airport it is shown that the algorithm is able to outperform the previously best exact algorithm from the literature. 11
  12. 12. MA-27 EURO-INFORMS - Rome 2013 3 - Finding bounds for the minimum number of moves for solving the WrapSlide puzzle Alewyn Burger, Department of Logistics, Stellenbosch University, Private Bag X1, Matieland, 7600, Stellenbosch, Western Cape, South Africa, WrapSlide is a slide-puzzle consisting of a 6 by 6 grid of tiles in which each quadrant of 3 by 3 tiles are coloured differently. The puzzle can be scrambled by performing a number of moves involving wrapping of tiles. A move consists of sliding either the top, bottom, left or right two quadrants of tiles 1 to 5 units horizontally or vertically. We discuss bounds on the minimum number of moves to unscramble the puzzle. 4 - A linear algorithm for secure domination in trees Jan van Vuuren, Department of Logistics, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, Western Cape, South Africa,, Alewyn Burger, Anton de Villiers A secure dominating set of a graph is an assignment of guards to its vertices, at most one guard per vertex, so that (a) every vertex is either occupied by a guard or adjacent to an accupied vertex and (b) there is a guard in the neighbourhood of each unoccupied vertex who can move to that vertex, again leaving a configuration satisfying (a) above. In this talk an algorithm is proposed for finding a secure dominating set of minimum cardinality for any tree in linear time and space. MA-27 Monday, 8:30-10:00 G9-8 Applications of Boolean Functions Stream: Boolean and Pseudo-Boolean Optimization Invited session Chair: Endre Boros, RUTCOR, Rutgers University, 08854, Piscataway, New Jersey, United States, 1 - Discovery of strong association rules in binary ta- bles based on hypergraph dualization Kira Adaricheva, Mathematical Sciences, Yeshiva University, 245 Lexington ave, 10016, New York, NY, United States, Discovery of (strong) association rules, or implications, is an important task in data management, that finds application in artificial intelligence, data mining and semantic web. We introduce the novel approach for the discovery of a specific set of implications, called the D-basis, that provides a representation for a binary table, based on the structure of its Galois lattice. At the core of the method is the D-relation defined in the lattice theory framework, and the hypergraph dualization algo- rithm that allows to effectively produce the set of transversals for a given hypergraph. 2 - The performance of box-type classifiers in the logical analysis of numerical data Martin Anthony, London School of Economics, WC2A 2AE, London, United Kingdom,, Joel Ratsaby The use of boxes for pattern classification is a fairly natural way in which to partition data into different classes or categories. It is one of the standard LAD approaches when dealing with numerical (rather than binary) data. We consider the performance of classifiers which are based on unions of boxes. The classification method studied may be described as follows: find boxes such that all points in the region enclosed by each box are assumed to belong to the same category, and then classify remaining points by considering their distances to these boxes. 3 - Quadratic reformulations of nonlinear binary opti- mization problems Yves Crama, HEC - Management School, University of Liège, Rue Louvrex 14 (N1), 4000, Liege, Belgium,, Martin Anthony, Endre Boros, Aritanan Gruber We consider the problem of minimizing a pseudo-Boolean function f(x), i.e., a real-valued function of 0-1 variables. Several authors have recently proposed to reduce this problem to the quadratic case by ex- pressing f(x) as min g(x,y) s.t. y = 0, 1, where g is a quadratic function of x and of additional binary variables y. We establish lower and up- per bounds on the number of additional y-variables needed in such a reformulation, both for the general case and for the special case of symmetric functions like positive or negative monomials, k-out-of-n majority functions, or parity functions. 4 - Threshold separability of boolean functions and its application to data discretization Giovanni Felici, Istituto di Analisi dei Sistemi ed Informatica, Consiglio Nazionale delle Ricerche, Viale Manzoni 30, 00185, Roma, Italy,, Endre Boros We consider the conditions for the existence of a Linear Threshold Function that separates two sets of Boolean vectors obtained by dis- cretization of real valued data. We state a combinatorial necessary and sufficient condition for the existence of such function when points be- long to the plane, and show its equivalency with a straight-forward interpretation of the Farkas’ Lemma. Such equivalency provides inter- esting insights for our problem in larger dimensions and supports the design of a discretization algorithm, for which we provide computa- tional experience and comparative tests. MA-28 Monday, 8:30-10:00 G9-2 Geometric Clustering 1 Stream: Geometric Clustering Invited session Chair: Belen Martin-Barragan, Dpto. Estadistica, Universidad Carlos III de Madrid, c/Madrid 126, 28903, Getafe, Madrid, Spain, 1 - On the existence of feasible power diagrams for op- timal weighted balanced clusterings Peter Gritzmann, Mathematics, TU München, Arcisstr. 21, D-80290, Munich, Germany,, Andreas Brieden A highly desirable property of a weighted clustering of points in d- space under balancing constraints is the existence of specific cell com- plexes that partition the space, and whose defining polyhedra con- tain the clusters, respectively. We introduce gravity polytopes and more general gravity bodies that encode all feasible clusterings and show that and how their extreme points correspond to strongly feasible power diagrams. Further, we characterize strongly feasible centroidal power diagrams in terms of the local optima of some ellipsoidal func- tion over the gravity polytope. 2 - Soft power diagrams Steffen Borgwardt, Fakultät für Mathematik, Technische Universität München, Boltzmannstr. 3, 85748, Garching, Bayern, Germany, In many applications, the points of a set in d-space are partitioned as a balanced least-squares assignment. Then there is a separating power diagram, for which each cluster lies in its own cell. In practice how- ever, data noise may destroy this nice property. We deal with this prob- lem by showing how to compute an optimal ’soft power diagram’ for general data sets: These are power diagrams for which we are able to control the number of points outside of their respective cluster’s cell. This leads to efficient algorithms for outlier detection and ’threshold- setting’. 12
  13. 13. EURO-INFORMS - Rome 2013 MA-30 3 - Approximation algorithm for plane polyhedral sepa- rability problem Konstantin Kobylkin, Optimization, IMM UB RAS, Sophya Kovalevskaya st., 16, 620990, Ekaterinburg, Sverdlovskaya, Russian Federation, We give an efficient approximation algorithm for an NP-hard sim- plest majority-based polyhedral separation problem for two sets on the plane which embeds minimum line covering problem as a special case. Specifically, we restrict separating lines to have positive constant terms which makes the problem approximately solvable within constant rel- ative accuracy in some cases. Results of experiments will be given in the talk on several problems of interest: polygon and star-like separa- ble integer-valued sets, mixtures of Gaussians, etc.. 4 - Nested Variable Neighborhood Search for Classifica- tion and Clustering. Belen Martin-Barragan, Dpto. Estadistica, Universidad Carlos III de Madrid, c/Madrid 126, 28903, Getafe, Madrid, Spain,, Emilio Carrizosa, Dolores Romero Morales Model selection is a critical issue in Data Analysis. Such selection involves the choice of a suitable distance, or a kernel. Enriching the models allows us to capture important information in the data, at the expense of tuning more parameters. Existing metaheuristics are ef- fective when the dimension of the parameter space is low, but tend to fail when it is high. We customize a continuous VNS that is able to cope with complex and flexible models that involve a larger number of parameters. We do it by exploiting the fact that rich models can be usually seen as generalization of simpler ones. MA-29 Monday, 8:30-10:00 G9-3 Management and control of queues Stream: Stochastic Modeling / Applied Probability Invited session Chair: Dieter Claeys, Department TELIN, Ghent University, B9000, Ghent, Belgium, Chair: Joris Walraevens, Department of Telecommunications and Information Processing, Ghent University, B9000, Ghent, Belgium, 1 - Performance evaluation of an overload control mech- anism in clustered servlet applications Marie-Ange Remiche, University of Namur, 5000, Namur, Belgium,, Laurent Schumacher Convergent Java Servlet infrastructure are key component in today’s cluster computing. They support services for many different types of protocols and applications. However, to remain reliable, an admission control algorithm is needed. One is defined based on the actual load of the servlet processor. A simple and efficient Markov model is build up to measure the performance of this admission control mechanism. Performance measures of interest are then obtained by means of matrix analytic technics. We validate our model in case of SIP traffic. 2 - Analysis and applications of coupled queues Eline De Cuypere, TELIN, University Ghent, St-Pietersnieuwstraat 41, 9000, Ghent, Belgium,, Koen De Turck, Dieter Fiems A coupled queueing system consists of multiple queues, served by a single server such that in every queue a customer leaves upon service completion, and such that service is blocked if any of the queues is empty. Coupled queueing systems are frequently encountered in vari- ous contexts including assembly, production and communication net- works. While conceptually simple, the analysis and performance of coupled queues is a challenging task, which draws upon different anal- ysis methodologies. We focus on several numerical techniques and develop a novel Taylor series expansion. 3 - Size-aware MDP approach to dispatching problems Samuli Aalto, Networking Laboratory, Helsinki University of Technology, P.O.Box 3000, FIN-02015, TKK, Finland,, Esa Hyytia Dispatching problems are related to parallel server systems where new jobs arrive dynamically and each job is assigned to one of the servers upon its arrival. Assuming Poisson arrivals, any static dispatching pol- icy can, in principle, be improved by the policy iteration technique developed in the MDP theory. We summarize many recent studies where the state of the queueing system is described based on the size information of jobs. In addition, we give illustrative examples where these iterated policies are compared to well-known dynamic dispatch- ing policies (such as JSQ and LWL). 4 - A queueing model for group-screening facilities Dieter Claeys, Ghent University, Belgium,, Joris Walraevens, Herwig Bruneel Classification of items can often be achieved more economically by screening the items in groups rather than individually. We model a group screening facility by a batch-service queueing model where the service (screening) time of a batch (group) is dependent on the number of customers (items) within it. We calculate the fraction of time the screening facility is screening and the average delay of items. These performance measures enable to evaluate every possible screening pol- icy by defining the dependency between the service time of a batch and the number of items within it appropriately. MA-30 Monday, 8:30-10:00 G9-10 Combinatorial Optimization & Applications Stream: Discrete and Global Optimization Invited session Chair: Mikhail Goubko, Institute of Control Sciences RAS, Russian Federation, Chair: Xianping Guo, Zhongshan University, China, 1 - Optimization of Cable Cycle: A Tradeoff between the Safety and Cost Barsam Payvar, School of Technology and Business Studies, University of Dalarna, Plogstigen 20 C, 78451, Borlänge, Dalarna, Sweden,, Hasan Fleyeh In networks, length of the path is a factor which plays a central role in the evaluation of the best path. In ring networks finding the short- est path is very hard. The problem is not a variation of the Traveling Salesman Problems (TSP) because the existence of Hamiltonian Cycle cannot be guaranteed. In such cases, the cycle may include more than one route which means increasing risk of losing more nodes during a failure. Thus, beside the cable length risk is another crucial factor. This work aims to optimize the network in order to find the shortest path with minimum risk. 2 - Charging Station Allocation for Selfish Electric Vehi- cles Takashi Tsubota, Department of Industrial and Systems Engineering, Aoyama Gakuin University, Chuo-ku,Fuchinobe,5-10-1, 2298558, Sagamihara, Kanagawa, Japan,, Shao-Chin Sung We are concerned with an allocation problem of charging stations for electric vehicles (EV). Since EV’s batteries have limited capacities, plan of charging and delays caused by charging itself and by queuing for charging have to be taken into consideration for routing of EVs. Hence, routing of EVs depends strongly on charging station alloca- tion. We propose a game theoretical approach based on an extended model of selfish routing game, in which each charging station is con- sidered as a player whose location is decided based on its incentive, and the allocations are provided by stable solutions. 13
  14. 14. MA-31 EURO-INFORMS - Rome 2013 3 - On Communication Network Topology Problem with Node Costs Mikhail Goubko, Institute of Control Sciences RAS, Russian Federation, The communication network topology problem is studied with no edge costs and node costs depending on the node degree and capacity. If cost depends on the degree only, the optimal network is shown to be the tree T of known cost. If capacity only matters, a two-layered network N is optimal where secondary nodes form a complete graph. When both de- gree and capacity matter, LB and UB are constructed using costs of T and N networks. A branch-and-bound procedure is designed. The lo- cal search heuristics is suggested and tested on a collection of random networks. 4 - Network Optimization Models for Resouce Allocation in Developing Military Countermeasures Boaz Golany, Industrial Engineering & Management, Technion - Israel Institute of Technology, Technion City, 32000, Haifa, Israel,, Moshe Kress, Michal Penn, Uriel G. Rothblum We consider an arms race where an attacker introduces new weapons to gain some advantage and a defender develops countermeasures that mitigate the weapons’ effects. We address the defender’s problem: given limited resources, which countermeasures to develop and how much to invest in them to minimize the damage caused by the weapons over a certain horizon. We formulate several models, corresponding to different operational settings as constrained shortest path problems and variants thereof. We then demonstrate the potential applicability and robustness of our approach in various scenarios. MA-31 Monday, 8:30-10:00 G9-11 Retail Assortment Planning Stream: Demand and Supply Planning in Consumer Goods and Retailing Invited session Chair: Heinrich Kuhn, Operations Management, Catholic University of Eichstaett-Ingolstadt, Auf der Schanz 49, 85049, Ingolstadt, Bavaria, Germany, 1 - Assortment planning and inventory management un- der stock-out based substitution for perishable prod- ucts Rob Broekmeulen, OPAC, TU Eindhoven, P.O. Box 516, Pav. E10, 5600 MB, Eindhoven, -, Netherlands,, Karel van Donselaar We study a combined assortment planning and inventory optimization problem for perishable products in a retail environment with stock-out based demand substitution. We develop a fast heuristic which enables the joint determination of optimal assortments and optimal reorder lev- els. We evaluated the impact of demand substitution on expected profit, outdating, assortment size and product availability. The impact of de- mand substitution on profit and outdating is large for product subcat- egories with a large assortment size, low total demand for the assort- ment, and small product lifetimes. 2 - Retail assortment, shelf space and inventory plan- ning Alexander Hübner, Operations Management, Catholic University Eichstaett-Ingolstadt, Auf der Schanz 49, 85049, Ingolstadt, Germany,, Heinrich Kuhn, Sabine Raettig Managing assortment, shelf space and inventory is a core decision in retail, as increasing product variety is in conflict with the limited shelf space. A retailer needs to define assortment size, assign shelf space and define reorder volume which then meets stochastic consumer demand. Our goal is to describe the underlying planning problem and develop a Newsboy-model. We describe a capacitated multi-product assort- ment, shelf space and inventory management problem under stochastic demand and substitution effects. Our numerical examples show signif- icant impact of substitution effects. 3 - Modeling Category Captaincy with Asymmetric Man- ufacturers Udatta Palekar, Business Administration, University of Illinois at Urbana-Champaign, 350 Wohlers Hall, 1206 S. Sixth Street, 61820, Champaign, Illinois, United States,, Erik Bushey Retailers are increasingly using category captains to manage multi- brand categories. We consider the asymmetric case where one brand has more brand-loyals than other. We develop a game-theoretic model to study the optimal strategy for the retailer and the two manufacturers. We present results that show when it is optimal for the retailer to select the smaller or larger manufacturer as a category captain. We find that for some situations it is not optimal for the retailer to have a category captain. We also discuss the gains/losses incurred by each player due to introduction of this category. MA-32 Monday, 8:30-10:00 G8-1 Supply Network Dynamics and Disruption Management Stream: Supply Chain Optimization Invited session Chair: Dmitry Ivanov, Supply Chain Management, Berlin School of Economics and Law, Germany, 1 - Modeling and Analysis of Supply Chain Viability Scott Mason, Clemson University, 124 Freeman Hall, 29634, Clemson, SC, United States,, Mariah Magagnotti, Kasin Ransikarbum Supply chain viability is a network’s ability to grow, expand, recover, and/or develop. Today, the degree to which a supply chain pos- sesses these important characteristics that we believe facilitate multi- dimensional performance is unmeasured. We present our research fo- cusing on the question of how and where should organizations spend available resources in order to improve the viability of their supply chain? We motivate our research using a variety of different supply chain types: functioning supply chains, damaged/interrupted networks, and disturbed/re-organized chains. 2 - Disturbances and plan deviations: Process control loops and quantitative analysis Dmitry Ivanov, Supply Chain Management, Berlin School of Economics and Law, Germany,, Boris Sokolov Integrated supply chain (SC) planning has been a visible research topic over the past two decades. Plan execution is subject to uncertainty. Disturbances may occur both in the flow/job shops and in the master planning environment and cause deviations in both schedules and mas- ter plans, influencing operative and tactical performance. Based on the mutli-disciplinary theory of quantitative analysis and practical cases, this study presents models and corresponding control processes for the control and adaptation of master plans and schedules in centralized multi-stage SCs. 3 - A State-space Model for Chemical Production Scheduling Christos Maravelias, Univeristy of Wisconsin - Madison, United States,, James Rawlings, Kaushik Subramanian We express a general mixed-integer programming (MIP) scheduling model in state-space form, and show how common scheduling dis- ruptions, which lead to rescheduling, can be modeled as disturbances. We also discuss how a wide range of scheduling models, with differ- ent types of decisions and processing constraints, can be expressed in state-space form. We hope that the proposed framework will lead to the development of scheduling solution methods with desired closed- loop properties, a topic that has received no attention in the process operations literature. 14
  15. 15. EURO-INFORMS - Rome 2013 MA-34 4 - Outsourcing negotiation under ambiguity and trust- worthiness: A Real Options Approach Yongling Gao, Business School, Central University of Finance and Economics, Haidian District Xueyuannan Road 39, 100081, Beijing, China,, T Driouchi We present an iterative negotiation method for partial outsourcing un- der ambiguity using real options with multiple-priors and bilevel pro- gramming. We obtain the lowest offer price for the vendor and optimal outsourcing proportion for the client, providing new insights into the role of (probabilistic) ambiguity in decision-making. We find that an increase in pessimism raises the vendor’s offer price under NPV but has an equivocal effect on the price when considering real options ef- fects. Meanwhile, the client unequivocally increases her optimal out- sourcing proportion under more pessimism. MA-33 Monday, 8:30-10:00 G8-3 Inventory management Stream: Production and the Link with Supply Chains Invited session Chair: Lionel Amodeo, Charles Delaunay Institute, University of Technology of Troyes, 12 Rue Marie Curie BP2060, 10000, Troyes, France, Chair: Jairo Montoya-Torres, Universidad de La Sabana, Colombia, and University of Leeds, UK, Leeds University Business School, Woodhouse Lane, LS2 9JT, Leeds, United Kingdom, 1 - Software design to storage centers, automation and optimization implementing EPC-RFID technologies Luis Ramirez, Fundacion Centro de Investigacion en Modelacion empresarial del caribe, Cra 53 No 74-86 ofic 402, Barranquilla, Atlantico, Colombia,, Diana Ramirez, Jairo Montoya-Torres, Erick Maldonado, Miguel Jimenez, Lauren Castro This paper shows the development of a decision support system for managing storage centers, with radio frequency technology for au- tomation and traceability and integrating optimization mechanisms and internal control processes. The paper shows in detail the system de- sign and how to operate the software integration with storage center based on RFID-WMS multi-criteria optimization Involving processes like picking, slotting and routing, seeking the improvement of man- agement practices, enhancing product traceability and showing process automation result of an applied research project. 2 - Solving the stochastic location-routing problem with ACO and Discrete-Event Simulation Nilson Herazo, Universidad de la Sabana Colombia and FCIMEC Colombia, Barranquilla, Atlántico, Colombia,, Santiago Nieto, Jairo Montoya-Torres, Luis Ramirez, Andres Munoz Villamizar We consider the minimisation of total travel cost in the location-routing problem (LRP) in which travel times and costs are both stochastic. A hierarchical solution approach based on Ant Colony Optimisation and Discrete-Event Simulation is proposed. Experiments are carried out using random data. Since this version of the problem has not been pre- viously studied in the literature, the proposed ACO-DES approach is compared against the non-stochastic version. Results are discussed in order to assess the actual impact of the system’s stochastic behaviour. 3 - Two-Stage Supply Chain Integration: Inventory Man- agement and Liner Service Optimization Ali Cheaitou, College of Engineering - Industrial Engineering and Management Department, University of Sharjah, Sharjah University City, 27272, Sharjah, United Arab Emirates,, Pierre Cariou When determining the optimal speed and number of vessels in a liner service, shipping companies would maximize their profit, although this choice may lead to significant increase in the transit time and conse- quently to a rise in inventory holding costs incurred by shippers. This paper proposes a model to investigate this trade-off in liner shipping market, through a comparison of a decentralized and a centralized sys- tem. Assuming that transport demand is normally distributed, this ar- ticle provides an optimization procedure along with an application to Europe/Far East services. 4 - Continuous Time Control of Make-to-Stock Produc- tion Systems Murat Fadiloglu, Industrial Engineering, Yasar University, Yasar Universitesi Endustri Muhendisligi Bolumu, Universite Caddesi Bornova, 35100, Izmir, Turkey, We consider the problem of production control and stock rationing in a make-to-stock production system with multiple servers —parallel pro- duction channels–, and several customer classes that generate inde- pendent Poisson demands. At decision epochs, in conjunction with the stock allocation decision, the control specifies whether to increase the number of operational servers or not. Previously placed production or- ders cannot be cancelled. We both study the cases of exponential and Erlangian processing times and model the respective systems as M /M /s and M /Ek /s make-to-stock queues. MA-34 Monday, 8:30-10:00 G8-4 Supply Risk and Reliability Stream: Supply Chain Risk Management Invited session Chair: Suresh Sethi, Jindal School of Management - ISOM, University of Texas at Dallas, 800 W. Campbell Rd. SM30, 75080, Richardson, TX, United States, 1 - How Does Pricing Power Affect a Firm’s Sourcing De- cisions from Unreliable Suppliers? Suresh Sethi, Jindal School of Management - ISOM, University of Texas at Dallas, 800 W. Campbell Rd. SM30, 75080, Richardson, TX, United States,, Tao Li We study sourcing decisions of price-setting and price-taking firms with unreliable suppliers. We define a supplier’s reliability in terms of the "size’ or "variability’ of his random capacity. With a price-setting firm, a supplier wins a larger order by increasing reliability. It is not always so with a price-taking firm. 2 - A reference model for analyzing corporate supply risk regarding scarce resources and components Mario Dobrovnik, Institute of Transport and Logistics Management, Vienna University of Business and Economics, Nordbergstrasse 15, 1090, Vienna, Vienna, Austria, This paper introduces a reference model for analyzing corporate sup- ply risk. It is an instrument for evaluating risk-mitigating strategies and serves as a source of information for knowledge-based risk deci- sions. It is based on product-related and environmental aspects as well as on the supply chain’s structure. Furthermore, a company’s knowl- edge about product composition, purchasing markets, and its supply chain are considered. The presented model enables firms to holisti- cally assess their purchasing practices in a standardized way and to take strategic action within its risk appetite. 3 - Critical Social Networking Project Team Attributes for Successful New Product Development Stamatia Kylindri, Institute of Technology and Innovation, University of Southern Denmark, Niels Bohrs Allé 1, DK-5230, Odense, Denmark,, George Blanas, Stoyan Tanev, Leif Henriksen 15