The safety and quality of agricultural raw materials are important in the food service industry because raw materials are temperature sensitive and perishable. Hence, they should be stored in cold storage and temperature-controlled truck to maintain quality and safety. This study investigates the current cold chain management of a chain restaurant. The objective is to identify the problems and suggest how to establish the proper cold storages and temperature-controlled trucks. The scope of the study is a restaurant having nine branches, two refrigerated containers (20 feet) for storing raw material and three temperature-controlled trucks for sending raw material to each branch. We conduct in-depth interviews with the restaurant owner and operators and check the temperature in cold storage and during transportation of raw material by using an infrared thermal camera and data logger to identify the problem. Then, we analyze the causes of the problem and suggest solutions for the improvement such as the design of cold storage and delivery platform. In summary, this research will be beneficial to other cold storage and temperature-controlled truck users. It can enhance the cold chain efficiency and food safety as well as energy cost-saving.

Recently, the topic of designing a closed loop supply chain network has attracted researcher’s attention. This is due to the enormous financial and environmental benefits obtained from closed loop supply chain practices. This paper addresses a new model of designing a closed loop supply chain network, which considers downward product substitution policy under four carbon emission regulation policies: carbon cap policy, carbon tax policy, carbon cap-and-trade policy and carbon offset policy. To solve the assumed uncertainties of product demand and number of products returned, robust optimization is adopted. The goal of the proposed model is to select which facility to open/operate, select a transportation mode and determine the quantity of shipped and substituted products. We show a numerical example of using the four carbon emission regulation policies.

City logistics, which started to examine as a subdivision of logistics, aims the planning and management of transportation, efficiency, protection of the environment, reduction of traffic, security, and energy-saving. Rapidly growing population and migration from rural to urban areas have an important place in many of the problems of cities. A smart city is an approach that has a significant potential to solve urban logistics problems with information technologies. "Smart city logistics solutions" such as full adaptive traffic management system, security, and emergency systems, electronic detection system, etc. present based on information technologies to meet the increasing demand for logistics services more efficiently, safely and environmentally. In this study, the evaluation of smart city logistics solutions that contain many components is considered as a multi-criteria decision-making (MCDM) problem. Given the complex nature of this problem and insufficient knowledge, the decision-making approach is supported by fuzzy logic. In this context, the smart city logistics solutions in Istanbul determined by literature review and expert opinions are modeled, analyzed, and the results are interpreted by using the House of Quality matrix of Quality Function Deployment (QFD) approach with fuzzy MCDM methods.

This paper considers the pickup and delivery problem with time windows (PDPTW). It is named as the single-commodity vehicle routing problem with pickups and deliveries, in which a fleet of vehicles satisfy a collection of customer requests. Each customer request requires the use of a single vehicle both to load a specified amount of one type of commodity at one location and to deliver them to another location. All requests must be performed without violating the vehicle capacity and the customer time windows specified for each location. In this study, we propose a novel Constraint Programming (CP) model for the PDPTW. CP is an exact solution approach which is well known for its abilities to express complex relationships and to obtain high-quality solutions within reasonable computational times for densely constrained combinatorial optimization problems such as the PDPTW. The performance of the proposed CP model is evaluated using benchmark instances from the literature. The computational results show that the proposed CP model is effective in finding high-quality solutions for large size problems.

Milk-run is one of the lean logistics implementations defined as a cyclic materials delivering system. In-plant milk-run system, a variant of milk-run, runs for the delivering materials within the plant from warehouse to assembly stations in a cyclic manner. It is implemented using Automated Guided Vehicles (AGV), which provide automated materials handling in plant. In this study, in-plant milk-run system is discussed and the importance of determining milk-run routes and period is emphasized. A mixed integer mathematical model is proposed for the determination of milk-run routes and its period simultaneously for AGVs. Besides, the mathematical model allows split deliveries for assembly stations. The proposed model is coded using GAMS software and the success of this model is shown on randomly generated test problems. The proposed model obtains the optimal solution approximately in 1 second for generated two test problems. This points out the advantage and practicability of the proposed mathematical model for in-plant milk-run system.

The studies about Electric Vehicles (EV) have gained importance and increased in the last years depending on the environmental concerns of the classic transportation systems. One of the problems to consider at this point is locating the proper points of electric charging stations for EVs. The primary objective of this research is to locate the electric charging stations in Istanbul considering the flow of the paths. The locations of electric charging stations are determined by using a mathematical model based on the flow-refuelling location model with the aim of maximizing the captured flow. The mathematical model is run for various values of “p” and the optimum locations are obtained.

The fact that the production and consumption amounts are different from each other gives a dynamic feature to the concept of storage. In addition, an effective storage activity hinges upon the selection of the right warehouse location that takes into account capital and labor investments; minimizes the transportation cost and time. The aim of this study is to investigate the preliminary researches in the selection of the warehouse location selection and to present information on which success factors and methods are preferred. Within this scope, many academic studies have been examined by filtering various databases. According to the results of the study, the most used methods in warehouse location selection are multi-criteria decision making methods such as AHP, ANP and TOPSIS; and the most commonly used success factor is determined as the cost-based factors.

In this study, we consider to improve efficiency of an after-sales technical service in home appliances industry. The efficiency measure is the total time spent in a day to serve customer requests. Hence, the objective is to minimize total working hours spent in a day in the after-sales services. We first analyze the system to identify causes of delays in job completion. Upon findings of our analysis we choose to focus on job assignment and job sequencing to improve efficiency. We propose a mixed integer programming model for the assignment of technicians to jobs and sequencing of jobs for each technician to minimize total time spent in a day. Through this model we solve the problem with expected job durations. We present a (two?) numerical study to illustrate the proposed solution procedure.

The accessibility of airports and the airport preference of users are significant criteria for the competitiveness of airports. When passengers choose a route, they actually expect the completion of the transportation chain and they want to travel to the door from the door. For this reason, the factors that affect the passenger's decision for a significant option go beyond the price and quality of air services. The decision for a specific air service and a particular airport depends on the accessibility of the airport to a considerable extent. Factors affecting the choice of the airport can simply be divided into two categories. The category that reflects the number of air fares, frequencies and served destinations is defined as "air side". The category of airport accessibility, namely access, is also called "land side". The locations of the airports are usually set up around the periphery of the city’s with a reasonable length such as 50 km. The access of the airports may affect the passenger demands, so this study investigate the Turkish airport coverage in length of 50, 75 and 100 km radius from city centers. The main purpose of this study thus investigates whether a new airport construction is needed or not for domestic flights. Results showed that if 100 km radius length is used as a criterion for building new airport, only 10 cities with total population of about 2.5 million people will be outside the airport access. Socio-economical features are highly related with the location choice of airports. Therefore, accessibility properties are compared with the special properties of the cities and possible new airport locations have been determined.

The number of microorganisms and chemical values of the milks separated according to their quality are different from each other. In case of mixing different quality types of milk, composed milk quality is considered equal to the lowest quality milk type among the types of milk added to the mixture. Therefore, different types of raw milk should not be mixed during collection. The problem of milk collection is related to the collection of raw milk, which is separated according to the quality types, from the producers at different points by multi-tank tankers. In this study, an integrated mathematical model has been developed to collect different quality types of raw milk at different points under the specified time limit by means of tankers having multiple tanks. The results obtained by solving a hypothetical case study with ILOG CPLEX show that proposed model allows to optimally collect different type of raw milks without mixing. Thus, it will be possible to produce higher quality dairy products.