A combined inventory routing and game theory approach for a real-world distribution problem

In this paper, we develop a solution approach combining inventory routing and game theory and discuss it application to solve a real-world distribution and logistics problem. The problem consists of developing a distribution plan to replenish inventory at the involved sales-points and then clustering these sales-points into groups willing to cooperate and share a part of their stocks. The distribution and clustering strategies should be developed in such a way so as to minimize distribution and inventory costs of the system. The cooperation inside each cluster increases the potential inventory to which each member of this cluster has access. This enhances, in tum, the service level of each sales-point. The approach is implemented for a real-life case and the obtained results are reported and discussed in this paper.Postprint (published version

Solving the single-period inventory routing problem with the deterministic approach

This paper considers the problem of managing inventory and routing problems in a two-stage supply chain system under a Vendor Managed Inventory (VMI) policy. VMI policy is an integrating decisions between a supplier and the customers. Thus, we assumed that the demand at each customer is stationary and the warehouse is implementing a VMI. The focus of this research is to optimize the inventory and the transportation costs of the customers for a twostage supply chain system. The problem is to define the delivery quantities, delivery times and routes to the customers for the single-period deterministic inventory routing problem (SP-DIRP) system. As a result, a linear mixedinteger program is established for the solutions of the SP-DIRP problem. A detailed analysis of an illustrative example for solving the SP-DIRP problem is presented to describe the integration of the proposed model

Una aproximación a través del modelo p-robusto para el problema estocástico de ruteo e inventario

Context: Approaches to logistics solutions through mathematical optimization are widely studied in the literature given their importance for business operations and their computational complexity. In this way, studying the uncertainty associated to operations is a key factor in modeling and decision-making. Method: A stochastic mathematical model is proposed for the Inventory Routing Problem (IRP), considering scenarios with variation in the demands. To obtain a suitable approach, a p-robustness approach and the reformulation of the classical IRP are presented. Results: The performed experiments show the benefits of including uncertainty through a p-robust approach when they are analyzed within an instance of the IRP. Moreover, given the selected modeling, the benefits of combining the approaches can be analyzed. Conclusions: The development of stochastic approaches for decision-making applied to the IRP allow analysts to handle uncertainty and also reduce the complexity of decision when combining different types of problems (Routing + Inventory) in the same model.Contexto: Las aproximaciones de soluciones logísticas a través de la optimización matemática son altamente estudiadas en la literatura debido a su importancia en las operaciones de las compañías y su complejidad computacional. En este sentido, el estudio de la incertidumbre asociada a la operación es un factor fundamental del modelamiento y la toma de decisiones. Método: Un modelo matemático estocástico es propuesto para el problema combinado de ruteo e inventario (IRP), considerando escenarios de variaciones en la demanda. Para obtener un enfoque adecuado, se presenta una aproximación de p-robusto y la reformulación del problema clásico de aplicación. Resultados: Los experimentos realizados muestran los beneficios de incluir la incertidumbre a través de la aproximación de p-robusto cuando se analizan en el marco de una instancia del IRP. También, dado el tipo de modelado seleccionado, se pueden analizar los beneficios de combinar las aproximaciones. Conclusiones: El desarrollo de aproximaciones estocásticas de toma de decisiones aplicadas al problema IRP permite a los analistas gestionar la incertidumbre y reducir la complejidad de las decisiones cuando se combinan diferentes tipos de problemas (Ruteo + Inventario) en un mismo modelo.

An Adaptive Large Neighborhood Search Heuristic for the Inventory Routing Problem with Time Windows

This research addresses an integrated distribution and inventory control problem which is faced by a large retail chain in the United States. In their current distribution network, a direct shipping policy is used to keep stores stocked with products. The shipping policy specifies that a dedicated trailer should be sent from the warehouse to a store when the trailer is full or after five business days, whichever comes first. Stores can only receive deliveries during a window of time (6 am to 6 pm). The retail chain is seeking more efficient alternatives to this policy, as measured by total transportation, inventory holding and lost sales costs. More specifically, the goal of this research is to determine the optimal timing and magnitudes of deliveries to stores across a planning horizon. While dedicated shipments to stores will be allowed under the optimal policy, options that combine deliveries for multiple stores into a single route should also be considered. This problem is modeled as an Inventory Routing Problem with time window constraints. Due to the complexity and size of this NP-hard combinatorial optimization problem, an adaptive large neighborhood search heuristic is developed to obtain solutions. Results are provided for a realistic set of test instances

Zaman pencereli ve değişken başlama zamanlı bir araç rotalama problemi için sütun türetme temelli matsezgiseller

In this study, a vehicle routing problem with time windows is investigated, where the costs depend on the total duration of vehicle routes and the starting time from the depot for each vehicle is determined by a decision maker. In order to solve the problem, two column generation based mat-heuristics are developed, where the first one makes use of the iterated local search and the second one uses the variable neighbourhood search. In order to assess the accuracy of the mat-heuristics, they are first compared with an exact algorithm on small instances taken from the literature. Since their performance are quite satisfactory, they are further tested on 87 large instances by running each algorithm 3 times for each instance. The computational results prove that the mat-heuristic using the variable neighbourhood search outperforms the other one. Hence, this enables to obtain a good feasible solution in a very short time when it is not possible to solve large instances with an exact solution method in a reasonable CPU time.Bu çalışmada, araçların kullanıldıkları süreye bağlı maliyetlerin oluştuğu ve araçların depodan başlama zamanının bir karar verici tarafından belirlendiği zaman pencereli bir araç rotalama problemi ele alınmaktadır. Problemi çözmek için biri yinelemeli yerel arama meta-sezgiselinden, diğeri değişken komşuluk arama meta-sezgiselinden yararlanan iki sütun türetme temelli mat-sezgisel geliştirilmiştir. Geliştirilen mat-sezgiseller ilk önce literatürden alınarak türetilen küçük bir veri kümesi üzerinde problemin eniyi sonucunu bulan kesin bir yöntem ile karşılaştırılarak kaliteli sonuçlar ürettiklerini kanıtlamışlardır. Yöntemlerin ürettikleri sonuçların doğruluk derecesinden emin olunduktan sonra, daha büyük 87 örnek üzerinde her mat-sezgisel her örnekte 3 kere çalıştırılarak test edilmiştir. Bilgisayımsal sonuçlar değişken komşuluk arama meta-sezgiseli kullanan mat-sezgiselin, daha kaliteli ve verimli sonuçlar vererek daha başarılı bir algoritma olduğunu göstermiştir. Bu sayede kesin bir yöntemle makul bir ana işlemci zamanında çözülemeyen büyük ölçülü problemler için çok kısa bir zaman içerisinde iyi bir olurlu çözüm elde etmek mümkün hale gelmiştir.TÜBİTAK BİDEBWOS:000486923100003Scopus - Affiliation ID: 60105072TR - DizinScience Citation Index ExpandedQ4ArticleUluslararası işbirliği ile yapılmayan - HAYIROcak2019YÖK - 2018-1

Optimization of the fuel chips production and distribution network with Forest and Landscape, Denmark

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Diseño de una cadena de suministro con un único producto usando programación lineal entera

En los últimos años, la globalización y los diversos cambios tecnológicos han contribuido en el desarrollo de la logística y la cadena de suministro, la cual se ha convertido en un todo para el funcionamiento eficiente de todos los involucrados. La correcta gestión de la cadena de suministro ha sido de gran importancia para el desarrollo empresarial, ha pasado de ser una operación más a convertirse en una de las áreas más intensivas en inversión, mano de obra, trabajo en equipo y sobre todo en la utilización de todo tipo de información..

An operational model for liquefied natural gas spot and arbitrage sales

As more buyers become interested in the spot purchase of liquefied natural gas (LNG), the share of spot trade in LNG business increases. This means that the cash flowing into the upstream of LNG projects is a combination of that generated by deliveries to long-term contract (LTC) customers and uncommitted product and arbitrage spot sales. LTC cash flows are more predictable while uncommitted product and arbitrage cash flows, affected by the dynamics of supply and demand, are more volatile and therefore less predictable. In this research, we formulate an inventory routing problem (IRP) which maximizes the profit of an LNG producer with respect to uncommitted product and arbitrage spot sales, and also LTC deliveries at an operational level. Using the model, the importance of arbitrage, interest rates and compounding frequency in profit maximization, and also the significance of interest rates and fluctuation in spot prices in decision-making for spot sales of uncommitted product are studied. It is proven that writing traditional LTCs with relaxed destination clauses which assist in arbitrage is beneficial to the LNG producer. However, in contrast to what was predicted neither the interest rate nor the compounding frequency has any importance in profit maximization when no change of selling strategy is observed. Apart from these, it is shown that there is a trade-off between the expectation of higher spot prices and the inventory and shipping costs in decision-making for spot sales of uncommitted product in the LNG industry. Finally, it is observed that the interest rate can affect the set of decisions on spot sales of uncommitted product, although the importance of such changes in profit remains to be further explored