Industrial Engineering
http://hdl.handle.net/10679/45
2024-03-28T18:06:49Z
2024-03-28T18:06:49Z
A novel collection optimisation solution maximising long-term profits: a case study in an international bank
Duman, Ekrem
Ecevit, F.
Çakır, Ç.
Altan, O.
http://hdl.handle.net/10679/9314
2024-03-25T10:30:32Z
2017-10-02T00:00:00Z
A novel collection optimisation solution maximising long-term profits: a case study in an international bank
Duman, Ekrem; Ecevit, F.; Çakır, Ç.; Altan, O.
When customers fail to pay the amount they owe to their bank related with a credit product (credit cards, overdraft accounts or instalment loans), the bank starts the collection process. This process typically lasts for a particular amount of time after which the customer is labelled as defaulted and a litigation period is launched. Banks try to minimise the percentage of credit exposure that goes to litigation since it negatively affects the bank’s profitability. Accordingly, they take various actions to maximise the collections before litigation. In this study, we approach this problem from a different perspective as we maximise not the short-term collections but the long-term revenues from customers by incorporating the churn effects of these actions in our modelling. © 2018 Informa UK Limited, trading as Taylor & Francis Group.
2017-10-02T00:00:00Z
International roaming traffic optimization with call quality
Şahin, Ahmet
Demirel, Kenan Cem
Albey, Erinç
Gürsun, Gonca
http://hdl.handle.net/10679/9296
2024-03-14T06:54:20Z
2019-01-01T00:00:00Z
International roaming traffic optimization with call quality
Şahin, Ahmet; Demirel, Kenan Cem; Albey, Erinç; Gürsun, Gonca
In this study we focus on a Steering International Roaming Traffic (SIRT) problem with single service that concerns a telecommunication’s operators’ agreements with other operators in order to enable subscribers access services, without interruption, when they are out of operators’ coverage area. In these agreements, a subscriber’s call from abroad is steered to partner operator. The decision for which each call will be forwarded to the partner is based on the user’s location (country/city), price of the partner operator for that location and the service quality of partner operator. We develop an optimization model that considers agreement constraints and quality requirements while satisfying subscribers demand over a predetermined time interval. We test the performance of the proposed approach using different execution policies such as running the model once and fixing the roaming decisions over the planning interval or dynamically updating the decisions using a rolling horizon approach. We present a rigorous trade off analysis that aims to help the decision maker in assessing the relative importance of cost, quality and ease of implementation. Our results show that steering cost is decreased by approximately 25% and operator mistakes are avoided with the developed optimization model while the quality of the steered calls is kept above the base quality level.
2019-01-01T00:00:00Z
Contributions to humanitarian and non-profit operations: Equity impacts on modeling and solution approaches
Koyuncu, Burcu Balçık
Smilowitz, K.
http://hdl.handle.net/10679/9289
2024-03-12T09:48:06Z
Contributions to humanitarian and non-profit operations: Equity impacts on modeling and solution approaches
Koyuncu, Burcu Balçık; Smilowitz, K.
Equity has been acknowledged as an important concern in designing and managing humanitarian and non-profit operations over the past decade. Given the significant demands for relief supplies created by a disaster and the scarcity of resources (such as supplies, vehicles, equipment), it is inevitable that some needs will be satisfied later than others, and effective prioritization is crucial. Relief organizations are faced with the challenge of finding ways to deliver resources in an equitable way to increase the chances of survival of people. These issues also emerge in the operations of non-profit organizations that allocate distribute scarce resources. Important contributions have been made by women in studying equity in humanitarian and non-profit operations, both in terms of practical insights and methodological advances. In this chapter, we review key papers written by women, which have advanced the literature in characterizing equity in humanitarian and non-profit operations and exploring the methodological implications of equity.
Robust reformulations of ambiguous chance constraints with discrete probability distributions
Yanıkoğlu, İhsan
http://hdl.handle.net/10679/9270
2024-03-07T16:58:53Z
2019-01-01T00:00:00Z
Robust reformulations of ambiguous chance constraints with discrete probability distributions
Yanıkoğlu, İhsan
This paper proposes robust reformulations of ambiguous chance constraints when the underlying family of distributions is discrete and supported in a so-called ``p-box'' or ``p-ellipsoidal'' uncertainty set. Using the robust optimization paradigm, the deterministic counterparts of the ambiguous chance constraints are reformulated as mixed-integer programming problems which can be tackled by commercial solvers for moderate sized instances. For larger sized instances, we propose a safe approximation algorithm that is computationally efficient and yields high quality solutions. The associated approach and the algorithm can be easily extended to joint chance constraints, nonlinear inequalities, and dependent data without introducing additional mathematical optimization complexity to that of the original robust reformulation. In numerical experiments, we first present our approach over a toy-sized chance constrained knapsack problem. Then, we compare optimality and computational performances of the safe approximation algorithm with those of the exact and the randomized approaches for larger sized instances via Monte Carlo simulation.
2019-01-01T00:00:00Z