Papers by Fulya Altiparmak
![Research paper thumbnail of A hyper heuristic for the green vehicle routing problem with simultaneous pickup and delivery](https://a.academia-assets.com/images/blank-paper.jpg)
Computers & Industrial Engineering, Mar 1, 2021
Abstract This paper studies the green vehicle routing problem with simultaneous pickup and delive... more Abstract This paper studies the green vehicle routing problem with simultaneous pickup and delivery (G-VRPSPD). It aims to minimize fuel consumption costs while satisfying customer pickup and delivery demands simultaneously. The fuel consumption is directly proportional to green house gas emissions. We mathematically formulate the problem, and develop a hyper-heuristic (HH-ILS) algorithm based on iterative local search and variable neighborhood descent heuristics to effectively solve the problem. Extensive computational experiments are conducted to analyze the impact of the G-VRPSPD and the HH-ILS. We investigate the effect of green objective function on total fuel consumption cost by comparing the G-VRPSPD with the VRPSPD. We perform comparative analysis to investigate the performance of HH-ILS. We also conduct sensitivity analysis to investigate the performance of neighborhood structures, hyper heuristic and local search. The results show that the green objective function has a significant effect on total fuel consumption cost. The HH-ILS algorithm yields competitive results when compared with the mathematical formulation and the state-of-the-art heuristics in the literature.
Selçuk Üniversitesi Sosyal Bilimler Enstitüsü Dergisi, 2004
Planlama (MİP) sistemi, stok maliyetlerini azaltırken verimliliği ve müşteri memnuniyetini artırm... more Planlama (MİP) sistemi, stok maliyetlerini azaltırken verimliliği ve müşteri memnuniyetini artırmayı hedefleyen bir üretim yönetim sistemidir. Son yıllarda, Türkiye'de özellikle imalat sanayiinde bir çok firma bu sistemi kullanmaya başlamış veya kullanmayı planlamaktadır. Her yeni sistemde olduğu gibi MİP sistemi, gerçek üretim sistemlerinin doğasında barındırdıkları karmaşıklığın ve belirsizliğin etkisiyle, başlangıç aşamasında pek çok güçlük içerir. Bu çalışmada, güneş enerjisi ve su ısıtma sistemleri imal eden bir işletmede, işlem sürelerindeki belirsizliğin Bulanık Küme Teorisi ile tanımlandığı durumda MİP sisteminin uygulanması incelenmektedir.
![Research paper thumbnail of Dağitim Ağlarinin Tasarimi Ve Eni̇yi̇lemesi̇ Kapsaminda Tedari̇k Zi̇nci̇ri̇ Ve Loji̇sti̇k Yöneti̇mi̇ne Bi̇r Bakiş: Son Geli̇şmeler Ve Genel Durum](https://attachments.academia-assets.com/113445625/thumbnails/1.jpg)
Supply chain management is concerned with optimization of the overall process of value creation f... more Supply chain management is concerned with optimization of the overall process of value creation from suppliers to last consumers. Thus, relations with the other firms are important as well as the production planning and control functions in the firm such as design, material handling, scheduling. In supply chain management, success means not an individual phenomenon but modeling and management of the complex business relations network. This paper presents a literature review on supply chain models to assist the decision maker for defining the problem structure and selecting an appropriate model based on basic characteristics of the problem. After we explain basic concepts of supply chain management, supply chain models under new classification have been analyzed. The classification includes deterministic, stochastic, fuzzy, simulation based, hybrid and information Technologies driven models.
![Research paper thumbnail of Çoklu şarj teknolojisine dayalı kısmi şarj politikalı karma filolu araç rotalama problemi: Matematiksel model ve çözüm kurucu sezgisel](https://attachments.academia-assets.com/113444159/thumbnails/1.jpg)
Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi
Bu çalışmada Çoklu Şarj Teknolojisine Dayalı Kısmi Şarj Politikalı Karma Filolu Elektrikli Araç R... more Bu çalışmada Çoklu Şarj Teknolojisine Dayalı Kısmi Şarj Politikalı Karma Filolu Elektrikli Araç Rotalama Problemi (KF-E-ARP) ele alınmıştır. Karma filo, elektrikli araçları (EA) ve konvansiyonel araçları (KA) içermektedir. Konvansiyonel araçların emisyon fonksiyonu ve elektrikli araçların şarj tüketim fonksiyonu içerisinde katedilen mesafe ile birlikte araçta taşınan yük miktarı da dikkate alınmıştır. Ayrıca şarj istasyonunda çoklu şarj konfigürasyonlarından birinin seçilmesi, karma filolu problemlerde ilk defa ele alınmıştır. Problem, müşteri dağıtım taleplerini karşılarken toplam maiyeti enazlayan araç rotalarının elde edilmesi olarak tanımlanabilir. KF-E-ARP için öncelikle karma tamsayılı matematiksel model geliştirilmiştir. Problem NP-zor olduğundan dolayı, orta ve büyük boyutlu problemlere makul sürelerde çözüm elde edebilmek amacıyla ekleme tabanlı bir çözüm kurucu sezgisel algoritma önerilmiştir. Deneysel analizlerde, matematiksel model ile 2 saat içerisinde çözüm bulunamayan...
![Research paper thumbnail of Kırsal alanlarda gezici sağlık hizmeti planlaması: Karma kayıttan kayıta gezinti algoritması](https://a.academia-assets.com/images/blank-paper.jpg)
Journal of The Faculty of Engineering and Architecture of Gazi University, Mar 19, 2023
Küreselleşme ve teknolojik gelişmelerle birlikte 21. Yüzyılın ikinci yarısında toplumların sağlık... more Küreselleşme ve teknolojik gelişmelerle birlikte 21. Yüzyılın ikinci yarısında toplumların sağlık ihtiyaçları değişmiş ve sağlık hizmeti sunumunda değişiklikler yapılması zorunlu hale gelmiştir. Nüfusun seyrek olduğu yerleşim yerlerinde kapsamlı sağlık tesisleri kurmanın ekonomik olarak sürdürülebilir olmaması, devletlerin vatandaşlarının sağlık hizmetlerine eşit erişimini sağlamakla yükümlü olması sağlık hizmeti sunumunda farklı arayışlara neden olmuştur. Türkiye Cumhuriyeti Sağlık Bakanlığı halka eşit şartlarda sağlık hizmeti sunabilmek için 3400 sağlık kuruluşu ve yaklaşık 7500 doktorla kırsal bölgelere gezici sağlık hizmeti (GSH) sunumu uygulamasını başlatmıştır. GSH sunan doktorlar günde 8 saat çalışarak her ay yaklaşık 9 milyon kişiye GSH vermektedir. Türkiye genelinde uygulanan kapsamlı bir hizmet olması nedeniyle hizmet sunumu planlaması için kırsal yerleşim bölgelerine sağlık merkezi ve doktor atama, rotalama, çizelgeleme ihtiyacı doğmuştur. Bu çalışmada, kırsal alanlarda GSH rotalama ve çizelgeleme problemi (GSH-RÇP) ele alınmıştır. GSH-RÇP’de amaç, çalışma saati, rota süresi, ziyaret başına minimum hizmet süresi, köylere her ay aynı doktorların hizmet sunması gibi kısıtlar altında, toplam katedilen mesafeyi enazlayacak şekilde aylık periyotlarda doktorların günlük rotalarını belirlemektir. Problemin çözümü için öncelikle karma tamsayılı matematiksel model geliştirilmiştir. GSH-RÇP, çok depolu zaman kısıtlı periyodik araç rotalama problemine eşdeğer olduğu için NP-zor problemler sınıfında yer almaktadır. Bu nedenle, orta ve büyük boyutlu problemlere makul sürelerde çözüm bulabilmek amacıyla bir karma sezgisel algoritma geliştirilmiştir. Açgözlü çözüm kurucu (Greedy Constructive) sezgiseli ve Kayıttan Kayıta Gezinti (Record to Record Travel) metasezgiseline dayalı olan bu karma sezgisel algoritma “AGS-KKG” olarak adlandırılmıştır. Matematiksel model ve AGS-KKG algoritmasının performansı Ankara iline ait verilere dayalı olarak mevcut planlar ile karşılaştırmalı incelenmiştir. Karşılaştırma sonucunda mevcut planlara göre toplam katedilen mesafede matematiksel model ile %15,6, AGS-KKG ile %22,3 iyileşme sağlanmıştır.
![Research paper thumbnail of Evde sağlık hizmetlerinde çok amaçlı, çok turlu ve zaman pencereli rotalama problemi için hedef programlama yaklaşımı](https://attachments.academia-assets.com/110053532/thumbnails/1.jpg)
Journal of The Faculty of Engineering and Architecture of Gazi University, Sep 2, 2021
Home health care routing problem has been defined. The test problems are produced based on the ... more Home health care routing problem has been defined. The test problems are produced based on the data and the information obtained from a hospital in Ankara. The problem in this study has been defined as a multi-objective, multitrip and time-windows home healthcare routing problem. Purpose: Apply a mixed integer programming model for multi trip vehicle routing with time window constraints (MTTW-HHCRP) for home health care services maximizing patient satisfaction while minimizing environmental effects. Theory and Methods: The problem addressed in this study has been defined as a multi-objective, multi-trip and time-windows home healthcare routing problem (MTTW-HHCRP). Weighted goal programming (GP) method is used to solve the problem. Results: Results are provided for a set of test problems generated from data obtained from a hospital in Ankara, Turkey for two different scenarios; 1-Analyze the effect of goal programming weights, 2-Analyze the effect of minimum percentage of patient demand to be met on solutions and performance metrics. For scenario 1, it is found that w1 ≥ 0.3 for the emissions to meet the target whereas in order to meet at least 50% of patient demands, w2 0.9. For scenario 2, the increase in minimum percentage of patient demand to meet causes an increase in resource requirements as expected. Conclusion: Based on the data and the information obtained from the hospital in Ankara, test problems are produced and the solutions obtained for each scenario analysis are evaluated to guide the decision-making process.
Expert Systems With Applications, Jun 1, 2023
... Fatma Pinar GOKSAL, Fulya ALTIPARMAK Department of Industrial Engineering Gazi University Ank... more ... Fatma Pinar GOKSAL, Fulya ALTIPARMAK Department of Industrial Engineering Gazi University Ankara, Turkey [email protected]; [email protected] ... The objective is to find a set of routes to service all customers while minimizing the total travel distance/time or the ...
![Research paper thumbnail of A Hybrid Genetic Algorithm for the Location-Routing Problem with Simultaneous Pickup and Delivery](https://attachments.academia-assets.com/110053559/thumbnails/1.jpg)
Industrial Engineering and Management Systems, Mar 1, 2011
In this paper, we consider the Location-Routing Problem with simultaneous pickup and delivery (LR... more In this paper, we consider the Location-Routing Problem with simultaneous pickup and delivery (LRPSPD) which is a general case of the location-routing problem. The LRPSPD is defined as finding locations of the depots and designing vehicle routes in such a way that pickup and delivery demands of each customer must be performed with same vehicle and the overall cost is minimized. Since the LRPSPD is an NP-hard problem, we propose a hybrid heuristic approach based on genetic algorithms (GA) and simulated annealing (SA) to solve the problem. To evaluate the performance of the proposed approach, we conduct an experimental study and compare its results with those obtained by a branch-and-cut algorithm on a set of instances derived from the literature. Computational results indicate that the proposed hybrid algorithm is able to find optimal or very good quality solutions in a reasonable computation time.
![Research paper thumbnail of Two-echelon vehicle routing problem with simultaneous pickup and delivery: Mathematical model and heuristic approach](https://attachments.academia-assets.com/110053556/thumbnails/1.jpg)
Computers & Industrial Engineering, 2018
The vehicle routing problem is one of the most important areas of logistics management. This stud... more The vehicle routing problem is one of the most important areas of logistics management. This study considers two-echelon vehicle routing problem with simultaneous pickup and delivery (2E-VRPSPD) which is a variant of vehicle routing problem. In the 2E-VRPSPD, the pickup and delivery activities are performed simultaneously by the same vehicles through depot to satellites in the first echelon and from satellites to customers in the second echelon. To solve the problem, firstly, a node-based mathematical model is proposed and three valid inequalities from the literature are adapted to strengthen the model. Because of the NP-hardness of the 2E-VRPSPD, secondly, a hybrid heuristic algorithm based on variable neighborhood descent (VND) and local search (LS), called VND_LS, is developed to solve medium-and large-size instances of the 2E-VRPSPD. We conduct an experimental study to investigate the effectiveness of the valid inequalities on the mathematical model and also to evaluate the effectiveness and efficiency of the VND_LS. Computational results show that valid inequalities have significant effect to strengthen the mathematical formulation. Furthermore, 2 the VND_LS finds good solutions for the problem efficiently. Finally, we apply the VND_LS to compare single-and two-echelon distribution systems for a supermarket chain located in Turkey. The results indicate that the VND_LS can easily be applied for real-world problems.
![Research paper thumbnail of The location-routing problem with simultaneous pickup and delivery: Formulations and a heuristic approach](https://a.academia-assets.com/images/blank-paper.jpg)
Omega, Aug 1, 2012
ABSTRACT In this paper, we consider a variant of the Location-Routing Problem (LRP), namely the L... more ABSTRACT In this paper, we consider a variant of the Location-Routing Problem (LRP), namely the LRP with simultaneous pickup and delivery (LRPSPD). The LRPSPD seeks to minimize total cost by simultaneously locating the depots and designing the vehicle routes that satisfy pickup and delivery demand of each customer at the same time. We propose two polynomial-size mixed integer linear programming formulations for the problem and a family of valid inequalities to strengthen the formulations. While the first formulation is a node-based formulation, the second one is a flow-based formulation. Furthermore, we propose a two-phase heuristic approach based on simulated annealing, tp_SA, to solve the large-size LRPSPD and two initialization heuristics to generate an initial solution for the tp_SA. We then empirically evaluate the strengths of the proposed formulations with respect to their ability to find optimal solutions or strong lower bounds, and investigate the performance of the proposed heuristic approach. Computational results show that the flow-based formulation performs better than the node-based formulation in terms of the solution quality and the computation time on small-size problems. However, the node-based formulation can yield competitive lower bounds in a reasonable amount of time on medium-size problems. Meantime, the proposed heuristic approach is computationally efficient in finding good quality solutions for the LRPSPD.
![Research paper thumbnail of Multiple Service Home Health Care Routing and Scheduling Problem: A Mathematical Model](https://a.academia-assets.com/images/blank-paper.jpg)
Advances in intelligent systems and computing, Jun 6, 2019
The home health care routing and scheduling problem (HHCRSP) is an extension of the vehicle routi... more The home health care routing and scheduling problem (HHCRSP) is an extension of the vehicle routing problem (VRP) that are scheduled and routed to perform a wide range of health care services. Nurses, doctors and/or caregivers provide these services at patients’ home. In this study, a mathematical model for HHCRSP is presented. The model is extended to take into account additional characteristics and/or constraints based on specific services, patient needs. In the home health care (HHC) problems, services that must be performed simultaneously or within a convinced time are undoubtedly very important. Thus, we consider several numbers of services, skill requirements for the care workers and time windows. Generally, the main aim of the HHC problems is minimizing the travelling distance as well as maximizing the patients’ satisfaction. Thus, the model in this study contains both of these objectives taking into account several measurements.
![Research paper thumbnail of Two Echelon Location Routing Problem with Simultaneous Pickup and Delivery: Mixed Integer Programming Formulations and Comparative Analysis](https://a.academia-assets.com/images/blank-paper.jpg)
Lecture Notes in Computer Science, 2016
This paper addresses the two-echelon location routing problem with simultaneous pickup and delive... more This paper addresses the two-echelon location routing problem with simultaneous pickup and delivery (2E-LRPSPD). The 2E-LRPSPD deals with optimally locating primary and secondary facilities, and integrating goods distribution from depots and collection from customers and secondary depots. To the best of our knowledge there is no previous study on this problem. We propose two mixed integer programming formulations for the 2E-LRPSPD. While the first formulation is a two-index node-based formulation, the second one is a two-index flow-based formulation. Moreover, a family of valid inequalities are adapted from the literature to strengthen the formulations. In order to evaluate the performances of the formulations and valid inequalities, we conduct an experimental study on the instances derived from the literature. The computational results show that the flow-based formulation produces better lower bounds than the node-based formulation on small and medium-size problems.
![Research paper thumbnail of A Mobile Healthcare Service Routing and Scheduling Problem in Rural Areas](https://a.academia-assets.com/images/blank-paper.jpg)
Springer eBooks, 2021
A change in health policy become essential since healthcare needs of societies have changed over ... more A change in health policy become essential since healthcare needs of societies have changed over the past sixty years. It is not possible to build a hospital wherever people live especially in less populated settlements. However, equal access of people to health services must be ensured by governments. To tackle this issue, Turkey Ministry of Health has enforced to give mobile healthcare services in rural areas by approximately 7.5 thousand doctors located in 3.4 thousand medical centers. These doctors work 8 h/day and give mobile healthcare service to approximately 9 million people each month. This study considers Turkey rural healthcare delivery system as a Multi-depot Time Constrained Periodic Vehicle Routing Problem (md-TCPVRP) and presents a mixed-integer linear programming formulation for the problem. The goal is to derive daily routes of the doctors each month, under some constraints such as maximum workhours, route duration, minimum service time per visit, assigning dedicated doctors to villages while minimizing the total route distance. In order to investigate the performance of the model a computational experiment is carried. The real-life application of Health Directorate of the province and proposed mathematical model results are compared. Computational results show significant improvements in total distances.
![Research paper thumbnail of A mathematical formulation and heuristic approach for the heterogeneous fixed fleet vehicle routing problem with simultaneous pickup and delivery](https://attachments.academia-assets.com/110053554/thumbnails/1.jpg)
Journal of Industrial & Management Optimization, 2017
This study considers a variant of the vehicle routing problem (VRP) called the heterogeneous VRP ... more This study considers a variant of the vehicle routing problem (VRP) called the heterogeneous VRP with simultaneous pickup and delivery (HVRPSPD). The HVRPSPD may broadly be defined as identifying the minimum cost routes and vehicle types. To solve the HVRPSPD, first, we propose a polynomial-size mixed integer programming formulation. Because the HVRPSPD is an NP-hard problem, it is difficult to determine the optimal solution in a reasonable time for moderate and large-size problem instances. Hence, we develop a hybrid metaheuristic approach based on the simulated annealing and local search algorithms called SA-LS. We conduct a computational study in three stages. First, the performance of the mathematical model and SA-LS are investigated on small and medium-size HVRPSPD instances. Second, we compare SA-LS with the constructive heuristics, nearest neighborhood and Clarke-Wright savings algorithms, adapted for the HVRPSPD. Finally, the performance of SA-LS is evaluated on the instances of the heterogeneous VRP (HVRP), which is a special case of the HVRPSPD. Computational results demonstrate that the mathematical model can solve small-size instances optimally up to 35 nodes; SA-LS provides good quality solutions for medium and large-size problems. Moreover, SA-LS is superior to simple constructive heuristics and can be a preferable solution method to solve HVRP and VRP-SPD instances successfully.
Endüstri Mühendisliği, 2005
ÖZET Gerçek hayatta karşılaşılan sistemler büyük boyutlu ve karmaşık olup birtakım belirsizlikler... more ÖZET Gerçek hayatta karşılaşılan sistemler büyük boyutlu ve karmaşık olup birtakım belirsizlikler içerdiğinde analitik çözümleri mümkün olmamaktadır. Bu tür sistemlerin bu karmaşık ve olasılıklı yapısından dolayı benzetim, mevcut sistemlerin performans ...
Transportation Research Part E: Logistics and Transportation Review
![Research paper thumbnail of Rekabetçi̇ Tesi̇s Yer Seçi̇mi̇ Problemleri̇ne İli̇şki̇n Bi̇r Tarama Çalişmasi](https://attachments.academia-assets.com/106097262/thumbnails/1.jpg)
Verimlilik Dergisi
Amaç: Bu çalışmanın amacı, son yıllarda Rekabetçi Tesis Yer Seçimi (RTYS) problemlerinin ve probl... more Amaç: Bu çalışmanın amacı, son yıllarda Rekabetçi Tesis Yer Seçimi (RTYS) problemlerinin ve problem bileşenlerinin literatürde ele alınış biçimlerine ilişkin bir bilimsel yayın taraması sunmaktadır. Yöntem: İlk olarak literatürde problemin temel bileşenlerinin ele alınış biçimlerine yer verilmiştir. Daha sonra RTYS problemi için literatürdeki en temel sınıflandırma kriteri olan rekabet tiplerine göre problem türleri incelenmiştir. Son olarak genişletilmiş RTYS problem türlerini ve çok amaçlı RTYS problemlerini ele alan çalışmalara yer verilmiş ve tarama çalışmasının sonuçları sunulmuştur. Bulgular: Tarama çalışması sonucu RTYS alanında gelecek vadeden çalışma konuları; birden fazla firmanın pazar paylarının enbüyüklenmesi amaçlarının çok-amaçlı olarak ele alındığı RTYS problemleri, müşterilerin tesis seçimlerinin çok amaçlı eniyileme kullanılarak yapıldığı RTYS problemleri, ikiden fazla rakip firma içeren RTYS problemleri olarak belirlenmiştir. Özgünlük: RTYS, hem tedarik zinciri iç...
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Papers by Fulya Altiparmak