A multiperiod drayage problem with customer-dependent service periods

We investigate a routing problem arising in the domain of drayage operations. to determine mimimum-cost vehicle routes in several periods. We adapt a set-covering model, which is solved either with all feasible routes by an off-the-shelf MIP solver, or by and a Price-and-Branch algorithm in which the pricing problem is a formulated as a collection of shortest path problems in tailor-made auxiliary acyclic networks. We propose a new arc-flow formulation based on the previous auxiliary networks and show that solving it by a MIP solver is usually preferable. Finally, we characterize how possible changes in flexibility levels affect routing costs

Yeşil depo yeri belirleme ve araç rotalama problemlerinin GA ve sezgisel metotlarla çözülmesi : boya imalat firmasında uygulanması

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Yer seçimi ve rotalama problemleri, lojistik problemlerinin en önemli konularından olup farklı yaklaşımlarla ve çözüm yöntemleri ile geliştirilerek daha özel hale getirilmiş problemlerdir. Bu çalışmada verimlilik ve karlılık oranlarını arttırmak için bir boya firmasının lojistik biriminde, kara lojistiğinin en önemli problemlerinden olan depo yeri seçimi ve rotalama problemine farklı yaklaşımlarla çözümler aranmaktadır. İki farklı model önerilmiştir. İlk modelde şehirlerarası km'leri dikkate alarak çözüm yolu önerisi getirilmiştir. İkinci modelde ise çevreye karşı farkındalığı arttırmak için dünyada hızla artan küresel ısınmanın en önemli sebeplerinden olan sera gazlarından CO2 emisyon miktarlarını yolların eğimini dikkate alarak azaltan çözüm yolu önerisi getirilmiştir. Yer seçimi ve rotalama problemine, depo-yer seçimi ve atama problemi, kapasiteli araç rotalama problemi olmak üzere kademeli yaklaşım önerilmiştir. Birinci aşamada problem Mixed-Integer Linear Programming (MILP)'de çözülerek atama yapılmıştır. Sonuç olarak tüm şehirler uygun depolara tahsis edilmiştir. İkinci aşamada kapasiteli araç rotalama problemi sezgisel algoritma ve genetik algoritma yöntemleri kullanılarak çözülmüştür. Önerilen modeller Marmara Bölgesi'nde boya fabrikasında uygulanmıştır. Sonuç olarak önerilen genetik algoritmaların model 1 ve model 2'de klasik sezgisel yöntemden daha avantajlı olduğu sonucuna varılmıştır.Location and routing problems are one of the most important issues of logistics problems and solved using different approaches. In this study, location and routing problems were solved in a logistic department of a paint firm to increase the productivity and profitability rates. Two different models were proposed. The first model was only related with kms among cities. At the second model, in order to raise awareness on the environment, greenhouse gases that are one of the most important reasons of global warming in the world, was included into the model to reduce CO2 emissions by taking into account the inclination of roads. A hierarchical approach was proposed to solve these problems. At the first level, an assignment to problem (MILP) was solved. As a result, all the cities were assigned to proper storages. At the second level, capacitated routing problem was solved using a heuristic and genetic algorithm. The proposed models were applied in a real life paint factory, in Marmara region, Turkey. The results illustrate that the proposed genetic algorithm produced better result than the classical heuristic method for model 1 and model 2

Diseño de una cadena de suministro con un único producto usando programación lineal entera

En los últimos años, la globalización y los diversos cambios tecnológicos han contribuido en el desarrollo de la logística y la cadena de suministro, la cual se ha convertido en un todo para el funcionamiento eficiente de todos los involucrados. La correcta gestión de la cadena de suministro ha sido de gran importancia para el desarrollo empresarial, ha pasado de ser una operación más a convertirse en una de las áreas más intensivas en inversión, mano de obra, trabajo en equipo y sobre todo en la utilización de todo tipo de información..

Inventory routing with pickups and deliveries

This paper introduces a class of problems which integrate pickup and delivery vehicle routing problems (PDPs) and inventory management, and we call them inventory routing problems with pickups and deliveries (IRP-PD). We consider a specific problem of this class, where a commodity is made available at several origins and demanded by several destinations. Time is discretized and transportation is performed by a single vehicle. A mathematical programming model is proposed together with several classes of valid inequalities. The models are solved with a branch-and-cut method. Computational tests are performed to show the effectiveness of the valid inequalities on instances generated from benchmark instances for the inventory routing problem. Results show that the branch-and-cut algorithm is able to solve to optimality 345 over 400 instances with up to 50 customers over 3 periods of time, and 142 over 240 instances with up to 30 customers and 6 periods. From a management perspective, results show that the average cost of a non integrated policy is more than 35% higher than the cost of an integrated policy

Inventory routing with pickups and deliveries

This paper introduces a class of problems which integrate pickup and delivery vehicle routing problems (PDPs) and inventory management, and we call them inventory routing problems with pickups and deliveries (IRP-PD). We consider a specific problem of this class, where a commodity is made available at several origins and demanded by several destinations. Time is discretized and transportation is performed by a single vehicle. A mathematical programming model is proposed together with several classes of valid inequalities. The models are solved with a branch-and-cut method. Computational tests are performed to show the effectiveness of the valid inequalities on instances generated from benchmark instances for the inventory routing problem. Results show that the branch-and-cut algorithm is able to solve to optimality 345 over 400 instances with up to 50 customers over 3 periods of time, and 142 over 240 instances with up to 30 customers and 6 periods. From a management perspective, results show that the average cost of a non integrated policy is more than 35% higher than the cost of an integrated policy