Endüstri Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/279

Browse

Filters

2022 - 20233

Settings

Access Right: Open AccessAuthor: search.filters.author.Aydemir-Karadag, Ayyuce

Search Results

Now showing 1 - 3 of 3
  • Article
    Design of a Distribution Network for the School Lunch Program
    (Academic Publication Council, 2023) Aydemir-Karadag, Ayyuce; Akdere, Erol; Karadag, Ayyuce Aydemir
    The national school lunch program (NSLP) is crucial for providing healthy, inexpensive, or free lunches to children, thus benefiting society. Designing a distribution network for the program requires solving a location and routing problem. In this paper, first, we formulate a multi -objective non-linear integer programming formulation of the problem. Next, we develop a two-step approach since the problem is Np-hard. The first stage presents a K -mean clustering method that deals with routing decisions by determining the locations of food processing centers and allocating schools to these centers. The second stage offers a multi -objective mixed -integer linear mathematical model for finding the locations of distribution centers. Besides economic and environmental factors, we optimize travel time in the network as perishable items are involved. A weighted sum approach is presented for different weights of objectives. We provide a real case study in Turkey to demonstrate the applicability of the two -stage approach proposed in this study. The numerical results provide valuable information for decision -makers and authorities to prioritize and prepare action plans.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Designing an Annual Leave Scheduling Policy: Case of a Financial Center
    (Amer inst Mathematical Sciences-aims, 2022) Aydemir-Karadag, Ayyuce; Yildirim, Gonca
    Providing annual leave entitlements for employees can help allevi-ate burnout since paid-time off work directly affects the health and productivity of workers as well as the quality of the service provided. In this paper, we de-velop realistic vacation scheduling policies and investigate how they compare from both the employer and the employees' perspectives. Among those poli-cies, we consider one that is used in practice, another that we propose as a compromise which performs very well in most cases, and one that is similar to machine scheduling for benchmarking. Integer programming models are for-mulated and solved under various settings for workload distribution over time, substitution and unit of time for vacations. We use three performance mea-sures for comparisons: penalty cost of unused vacation days, percent vacation granted and level of employee satisfaction. We provide a real-life case study at a bank's financial center. Numerical results suggest that an all-or-nothing type of vacation policy performs economically worse than the others. Attrac-tive annual leave scheduling policies can be designed by administering vacation schedules daily rather than weekly, ensuring full cover for off-duty employees, and offering employees some degree of choice over vacation schedules.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 27
    Bi-Objective Adaptive Large Neighborhood Search Algorithm for the Healthcare Waste Periodic Location Inventory Routing Problem
    (Springer Heidelberg, 2022) Aydemir-Karadag, Ayyuce
    There has been an unexpected increase in the amount of healthcare waste during the COVID-19 pandemic. Managing healthcare waste is vital, as improper practices in the waste system can lead to the further spread of the virus. To develop effective and sustainable waste management systems, decisions in all processes from the source of the waste to its disposal should be evaluated together. Strategic decisions involve locating waste processing centers, while operational decisions deal with waste collection. Although the periodic collection of waste is used in practice, it has not been studied in the relevant literature. This paper integrates the periodic inventory routing problem with location decisions for designing healthcare waste management systems and presents a bi-objective mixed-integer nonlinear programming model that minimizes operating costs and risk simultaneously. Due to the complexity of the problem, a two-step approach is proposed. The first stage provides a mixed-integer linear model that generates visiting schedules to source nodes. The second stage offers a Bi-Objective Adaptive Large Neighborhood Search Algorithm (BOALNS) that processes the remaining decisions considered in the problem. The performance of the algorithm is tested on several hypothetical problem instances. Computational analyses are conducted by comparing BOALNS with its other two versions, Adaptive Large Neighborhood Search Algorithm and Bi-Objective Large Neighborhood Search Algorithm (BOLNS). The computational experiments demonstrate that our proposed algorithm is superior to these algorithms in several performance evaluation metrics. Also, it is observed that the adaptive search engine increases the capability of BOALNS to achieve high-quality Pareto-optimal solutions.