Bülent Çatay

Third‐party logistics provider selection: insights from a Turkish automotive company

Purpose – The purpose of this paper is to highlight the efforts of a leading Turkish automotive company to restructure its supply chain for export parts.Design/methodology/approach – The paper presents hand‐on experiences of a pilot project conducted at Tofas‐Fiat automotive company to redesign its logistics operations and to select a global logistics service provider, using an analytic hierarchy process for multi‐criteria decision‐making.Findings – 3PL providers in Turkey must improve their capabilities and act proactively in providing value‐adding services as the companies are becoming more demanding in their expectations in building strategic relationships.Research limitations/implications – The focus of the paper is on automotive supply chain for export parts, but the analysis as well as 3PL selection methodology may be successfully applied to other products in different settings and in other sectors.Practical implications – Companies must determine logistics goals and requirements prior to taking on ...

A decision support system for machine tool selection

Globalization of business, the worldwide competitive economy and the decrease in product life force companies to use new equipments that are continuously introduced to the market with the advances in technology. An improper selection can negatively affect productivity, precision, flexibility and company’s responsive manufacturing capabilities. Thus, selecting the most suitable machine from the increasing number of available machines can be highly demanding. A decision support system is developed for the selection of machine tools. It will guide the selection process and help a decision maker solve the selection problem. Multi‐criteria weighted average is used in decision‐making process to rank the machines evaluated with respect to several criteria. The method is demonstrated with an example.

A new saving-based ant algorithm for the Vehicle Routing Problem with Simultaneous Pickup and Delivery

The Vehicle Routing Problem with Pickup and Delivery (VRPPD) is a variant of the Vehicle Routing Problem where the vehicles are not only required to deliver goods but also to pick up some goods from the customers. Given a fleet of vehicles and a set of customers with known delivery and/or pickup demands for one commodity VRPPD determines a set of vehicle routes originating and ending at a single depot and visiting all customers exactly once. The objective is to minimize the total distance traversed. In this paper, we consider a special case of the VRPPD where each customer has both a delivery and a pickup demand to be satisfied simultaneously. For this problem, we propose an ant colony algorithm employing a new saving-based visibility function and pheromone updating procedure. The numerical tests with the well-known benchmark problems from the literature show that the proposed approach provides competitive results and improves several best-known solutions.

Strategic level three-stage production distribution planning with capacity expansion

In this paper, we address a strategic planning problem for a three-stage production-distribution network. The problem under consideration is a single-item, multi-supplier, multi-producer, and multi-distributor production-distribution network with deterministic demand. The objective is to minimize the costs associated with production, transportation, and inventory as well as capacity expansion costs over a given time horizon. The limitations are the production capacities of the suppliers and producers, and transportation capacities of the corresponding transportation network. On the other hand, all capacities may be increased at a fixed cost. The problem is formulated as a 0-1 mixed integer programming model. Since the problem is intractable for real life cases efficient relaxation-based heuristics are considered to obtain a good feasible solution.

Competition through collaboration: insights from an initiative in the Turkish textile supply chain

Purpose – To gain an understanding of the benefits, bridges, and barriers associated with supply chain collaboration.Design/methodology/approach – Insights from extensive field research of a successful collaboration example in the Turkish dyeing and finishing industry.Findings – The competition among firms is increasingly shifting from company vs company to supply chain vs supply chain. The insights obtained from the collaborative model in this textile supply chain provide a good understanding of the benefits, bridges, and barriers associated with supply chain collaboration. Benefits can be grouped as customer‐oriented benefits, productivity benefits, and innovation related benefits. Factors supporting collaboration are observed as trust, common goals for cooperation, and existence of cooperation mechanisms, while barriers are related to three factors: lack of trust, risk‐benefit evaluation, and lack of common goals for cooperation.Research limitations/implications – Findings are based on interviews and q...

A multi-period double coverage approach for locating the emergency medical service stations in Istanbul

We consider the multi-period location planning problem of emergency medical service (EMS) stations. Our objective is to maximize the total population serviced by two distinct stations within two different response time limits over a multi-period planning horizon. Our aim is to provide a backup station in case no ambulance is available in the closer station and to develop a strategic plan that spans multiple periods. In order to solve this problem, we propose a Tabu Search approach. We demonstrate the effectiveness of the proposed approach on randomly generated data. We also implement our approach to the case of Istanbul to determine the locations of EMS stations in the metropolitan area.

Tool capacity planning in semiconductor manufacturing

The demand for distinct wafer types in semiconductor manufacturing is an explicit function of the electronic components in which these wafers are used. Given that the component demands vary not only by the product type but also over time, it is obvious that wafer demands are also lumpy and time varying. In this paper, we discuss strategic level investment decisions on procuring new equipment and aggregate level capacity planning. In this context, we examine the problem of planning wafer production over multiple time periods within a single facility assuming that a demand forecast for each wafer type for each period is known. To address this problem, we develop a multi-period mixed-integer programming model to minimize the machine tool operating costs, new tool acquizition costs, and inventory holding costs. Given that production of wafers requires a large number of operations with multiple tools capable of performing each operation, tool operating costs are explicitly minimized by integrating the assignment of specific operations to tools in our model. Since our model is computationally intractable, we propose a Lagrangean-based relaxation heuristic to find efficient tool procurement plans.

A taxonomy for emergency service station location problem

The emergency service station (ESS) location problem has been widely studied in the literature since 1970s. There has been a growing interest in the subject especially after 1990s. Various models with different objective functions and constraints have been proposed in the academic literature and efficient solution techniques have been developed to provide good solutions in reasonable times. However, there is not any study that systematically classifies different problem types and methodologies to address them. This paper presents a taxonomic framework for the ESS location problem using an operations research perspective. In this framework, we basically consider the type of the emergency, the objective function, constraints, model assumptions, modeling, and solution techniques. We also analyze a variety of papers related to the literature in order to demonstrate the effectiveness of the taxonomy and to get insights for possible research directions.

Finding a minimum cost path between a pair of nodes in a time-varying road network with a congestion charge

The minimum cost path problem in a time-varying road network is a complicated problem. The paper proposes two heuristic methods to solve the minimum cost path problem between a pair of nodes with a time-varying road network and a congestion charge. The heuristic methods are compared with an alternative exact method using real traffic information. Also, the heuristic methods are tested in a benchmark dataset and a London road network dataset. The heuristic methods can achieve good solutions in a reasonable running time.

Design of an RFID-based Manufacturing Monitoring and Analysis System

Radio frequency identification (RFID) technology has become an important driver in the production and logistics activities of todays information-based industries and economies. With the innovative developments in information and communication technologies, companies focus more on how these changes can be implemented and promoted in order to improve their value-added processes. This paper presents one such implementation approach for the monitoring and analysis of a discrete manufacturing environment using the RFID technology. Our aim is to bridge the gap between the physical flow of materials on the shop floor and manufacturing information and execution systems by allowing a rapid development and deployment of an RFID-based manufacturing automation solution.