Proposing an alternative allocation algorithm for smartphones: the case of Forall Phones

The refurbished market has grown at a considerable pace in recent years. The development of this market is due to the efforts of several countries to move to circular resource consumption that defines a circular economy (Mugge, Jockin, & Bocken, 2017). This is possible by reducing the waste created and reusing materials that would end up in the waste that are used again as resources (European Commission, 2019). This change has been accepted by organizations and their customers who are beginning to see the refurbished market as a great opportunity. Companies see the opportunity to dispose of used product stocks and recover some of their value (Weelden, Bakker, & Mugge, 2016). Customers see the opportunity to buy fully functional products at a fraction of the original price. The development and growth of the refurbished market has been quite noticeable in the smartphone segment, including in Portugal, where Forall Phones has been excelling. It was in the logistics area, in the allocation of smartphones to sales channels, that this project was carried out (a key area for the company's performance), with the aim of improving the allocation of smartphones to sales channels. After mapping the processes, some opportunities for improvement were identified. Then feedback on the approach (designed to respond to opportunities for improvement) was applied and implemented in Excel. The approach was then compared with other approaches being afterwards suggested some recommendations to further improve its performance.O mercado dos recondicionados tem crescido a um ritmo considerável nos últimos anos. O desenvolvimento deste mercado deve-se ao esforço de vários países em mudar para um consumo circular de recursos que é o que define uma economia circular (Mugge, Jockin, & Bocken, 2017). Isto é possível ao reduzir-se o lixo criado e ao reaproveitar materiais que iriam parar ao lixo, voltando a usá-los como recursos (European Comission, 2019). Esta mudança tem sido aceite pelas organizações e pelos seus clientes que começam a ver o mercado dos recondicionados como uma grande oportunidade. As empresas vêem a oportunidade de escoar stocks de produtos usados e de recuperar parte do seu valor (Weelden, Bakker, & Mugge, 2016). Os clientes vêem a oportunidade de comprarem produtos completamente funcionais a uma fração do preço original. O desenvolvimento e crescimento do mercado dos recondicionados tem sido bastante notório no segmento dos smartphones, incluindo em Portugal, onde a Forall Phones tem sobressaído. Foi na área logística que este projecto foi realizado (uma área fulcral para a performance da empresa), sendo o objectivo melhorar a alocação de smartphones aos canais de venda. Após o mapeamento dos processos foram identificadas algumas oportunidades de melhoria. De seguida o feedback relativamente à abordagem (criada para dar resposta às oportunidades de melhoria) foi aplicado e esta foi implementada em Excel. A abordagem foi depois comparada com outras abordagens, sugerindo-se depois recomendações para melhorar ainda mais o seu desempenho

Mathematical Methods and Operation Research in Logistics, Project Planning, and Scheduling

In the last decade, the Industrial Revolution 4.0 brought flexible supply chains and flexible design projects to the forefront. Nevertheless, the recent pandemic, the accompanying economic problems, and the resulting supply problems have further increased the role of logistics and supply chains. Therefore, planning and scheduling procedures that can respond flexibly to changed circumstances have become more valuable both in logistics and projects. There are already several competing criteria of project and logistic process planning and scheduling that need to be reconciled. At the same time, the COVID-19 pandemic has shown that even more emphasis needs to be placed on taking potential risks into account. Flexibility and resilience are emphasized in all decision-making processes, including the scheduling of logistic processes, activities, and projects

Applications of biased-randomized algorithms and simheuristics in integrated logistics

Transportation and logistics (T&L) activities play a vital role in the development of many businesses from different industries. With the increasing number of people living in urban areas, the expansion of on-demand economy and e-commerce activities, the number of services from transportation and delivery has considerably increased. Consequently, several urban problems have been potentialized, such as traffic congestion and pollution. Several related problems can be formulated as a combinatorial optimization problem (COP). Since most of them are NP-Hard, the finding of optimal solutions through exact solution methods is often impractical in a reasonable amount of time. In realistic settings, the increasing need for 'instant' decision-making further refutes their use in real life. Under these circumstances, this thesis aims at: (i) identifying realistic COPs from different industries; (ii) developing different classes of approximate solution approaches to solve the identified T&L problems; (iii) conducting a series of computational experiments to validate and measure the performance of the developed approaches. The novel concept of 'agile optimization' is introduced, which refers to the combination of biased-randomized heuristics with parallel computing to deal with real-time decision-making.Las actividades de transporte y logística (T&L) juegan un papel vital en el desarrollo de muchas empresas de diferentes industrias. Con el creciente número de personas que viven en áreas urbanas, la expansión de la economía a lacarta y las actividades de comercio electrónico, el número de servicios de transporte y entrega ha aumentado considerablemente. En consecuencia, se han potencializado varios problemas urbanos, como la congestión del tráfico y la contaminación. Varios problemas relacionados pueden formularse como un problema de optimización combinatoria (COP). Dado que la mayoría de ellos son NP-Hard, la búsqueda de soluciones óptimas a través de métodos de solución exactos a menudo no es práctico en un período de tiempo razonable. En entornos realistas, la creciente necesidad de una toma de decisiones "instantánea" refuta aún más su uso en la vida real. En estas circunstancias, esta tesis tiene como objetivo: (i) identificar COP realistas de diferentes industrias; (ii) desarrollar diferentes clases de enfoques de solución aproximada para resolver los problemas de T&L identificados; (iii) realizar una serie de experimentos computacionales para validar y medir el desempeño de los enfoques desarrollados. Se introduce el nuevo concepto de optimización ágil, que se refiere a la combinación de heurísticas aleatorias sesgadas con computación paralela para hacer frente a la toma de decisiones en tiempo real.Les activitats de transport i logística (T&L) tenen un paper vital en el desenvolupament de moltes empreses de diferents indústries. Amb l'augment del nombre de persones que viuen a les zones urbanes, l'expansió de l'economia a la carta i les activitats de comerç electrònic, el nombre de serveis del transport i el lliurament ha augmentat considerablement. En conseqüència, s'han potencialitzat diversos problemes urbans, com ara la congestió del trànsit i la contaminació. Es poden formular diversos problemes relacionats com a problema d'optimització combinatòria (COP). Com que la majoria són NP-Hard, la recerca de solucions òptimes mitjançant mètodes de solució exactes sovint no és pràctica en un temps raonable. En entorns realistes, la creixent necessitat de prendre decisions "instantànies" refuta encara més el seu ús a la vida real. En aquestes circumstàncies, aquesta tesi té com a objectiu: (i) identificar COP realistes de diferents indústries; (ii) desenvolupar diferents classes d'aproximacions aproximades a la solució per resoldre els problemes identificats de T&L; (iii) la realització d'una sèrie d'experiments computacionals per validar i mesurar el rendiment dels enfocaments desenvolupats. S'introdueix el nou concepte d'optimització àgil, que fa referència a la combinació d'heurístiques esbiaixades i aleatòries amb informàtica paral·lela per fer front a la presa de decisions en temps real.Tecnologies de la informació i de xarxe

A Metaheuristic-Based Simulation Optimization Framework For Supply Chain Inventory Management Under Uncertainty

The need for inventory control models for practical real-world applications is growing with the global expansion of supply chains. The widely used traditional optimization procedures usually require an explicit mathematical model formulated based on some assumptions. The validity of such models and approaches for real world applications depend greatly upon whether the assumptions made match closely with the reality. The use of meta-heuristics, as opposed to a traditional method, does not require such assumptions and has allowed more realistic modeling of the inventory control system and its solution. In this dissertation, a metaheuristic-based simulation optimization framework is developed for supply chain inventory management under uncertainty. In the proposed framework, any effective metaheuristic can be employed to serve as the optimizer to intelligently search the solution space, using an appropriate simulation inventory model as the evaluation module. To be realistic and practical, the proposed framework supports inventory decision-making under supply-side and demand-side uncertainty in a supply chain. The supply-side uncertainty specifically considered includes quality imperfection. As far as demand-side uncertainty is concerned, the new framework does not make any assumption on demand distribution and can process any demand time series. This salient feature enables users to have the flexibility to evaluate data of practical relevance. In addition, other realistic factors, such as capacity constraints, limited shelf life of products and type-compatible substitutions are also considered and studied by the new framework. The proposed framework has been applied to single-vendor multi-buyer supply chains with the single vendor facing the direct impact of quality deviation and capacity constraint from its supplier and the buyers facing demand uncertainty. In addition, it has been extended to the supply chain inventory management of highly perishable products. Blood products with limited shelf life and ABO compatibility have been examined in detail. It is expected that the proposed framework can be easily adapted to different supply chain systems, including healthcare organizations. Computational results have shown that the proposed framework can effectively assess the impacts of different realistic factors on the performance of a supply chain from different angles, and to determine the optimal inventory policies accordingly

MRP and Scheduling integration: A case study for the food industry

En este proyecto, se estudió una empresa encargada de elaborar productos alimenticios, con un proceso de producción complejo. Esta empresa no dispone de herramientas o metodologías para analizar el comportamiento de las variables, que en la literatura son consideradas importantes para planificar adecuadamente un determinado período de tiempo. Por esta razón, el foco del proyecto está en la planificación y ejecución del proceso productivo de la empresa. Para solucionar este problema, se propone una secuencia que vincula la metodología de planeamiento con la metodología de ejecución, donde ambas tienen objetivos diferentes, pero sus resultados son utilizados para retroalimentar el proceso en general, logrando un mejor desempeño en la utilización de materias primas y la reducción de posibles faltantes, que al final influyen en la reducción de los costos de producción, generando mayores ganancias para la empresa. La secuencia parte del desarrollo por separado de herramientas, que en primer lugar dan solución a la planificación del abastecimiento de materias primas para atender la demanda prevista, y en segundo lugar, la creación de herramientas que establecen un plan de producción, indicando el orden de los trabajos a realizar y proporcionando una idea de la capacidad productiva actual de la empresa. Para comprobar la eficacia de las metodologías, se utilizaron los datos de la empresa relacionados con los tiempos de procesamiento de los puestos, las máquinas, las cantidades producidas para cada día y las demandas históricas de la empresa. Se analizaron todos esos datos y se construyó un modelo de simulación para ajustar la metodología final. De hecho, una parte importante del proceso fue el trabajo en colaboración con la empresa, ya que se recibió feedback a través de la comunicación de los resultados.In this project, a company in charge of producing food products, with a complex production process, was studied. This company does not have tools or methodologies to analyze the behavior of variables, which in the literature are considered important to adequately plan a specific period of time. For this reason, the focus of the project is on the planning and execution of the company's production process. To solve this problem, a sequence is proposed that links the planning methodology with the execution methodology, where both have different objectives, but their results are used to feed back the process in general, achieving a better performance in the use of raw materials and the reduction of possible shortages, which in the end influence the reduction of production costs, generating more profits for the company. The sequence starts from the separate development of tools, which firstly provide a solution to the planning of the supply of raw materials to meet the forecasted demand, and secondly, the creation of tools that establish a production plan, indicating the order of the work to be done and providing an idea of the current production capacity of the company. To test the effectiveness of the methodologies, company’s data related to processing times of the stations, machines, quantities produced for each day and the historical demands of the company was used. All those data were analyzed, and a simulation model was built to adjust the final methodology. Indeed, an important part of the process was the collaborative work with the company, since feedback was received through the communication of the results.Ingeniero (a) IndustrialPregrad

A Special Case of the Multiple Traveling Salesmen Problem in End-of-Aisle Picking Systems

This study focuses on the problem of sequencing requests for an end-of-aisle automated storage and retrieval system in which each retrieved load must be returned to its earlier storage location after a worker has picked some products from the load. At the picking station, a buffer is maintained to absorb any fluctuations in speed between the worker and the storage/retrieval machine. We show that, under conditions, the problem of optimally sequencing the requests in this system with a buffer size of m loads forms a special case of the multiple traveling salesmen problem in which each salesman visits the same number of cities. Several interesting structural properties for the problem are mathematically shown. In addition, a branch-and-cut method and heuristics are proposed. Experimental results show that the proposed simulated annealing-based heuristic performs well in all circumstances and significantly outperforms benchmark heuristics. For instances with negligible picking times for the worker, we show that this heuristic provides solutions that are, on average, within 1.8% from the optimal value

Management, Technology and Learning for Individuals, Organisations and Society in Turbulent Environments

This book presents the collection of fifty papers which were presented in the Second International Conference on BUSINESS SUSTAINABILITY 2011 - Management, Technology and Learning for Individuals, Organisations and Society in Turbulent Environments , held in Póvoa de Varzim, Portugal, from 22ndto 24thof June, 2011.The main motive of the meeting was growing awareness of the importance of the sustainability issue. This importance had emerged from the growing uncertainty of the market behaviour that leads to the characterization of the market, i.e. environment, as turbulent. Actually, the characterization of the environment as uncertain and turbulent reflects the fact that the traditional technocratic and/or socio-technical approaches cannot effectively and efficiently lead with the present situation. In other words, the rise of the sustainability issue means the quest for new instruments to deal with uncertainty and/or turbulence. The sustainability issue has a complex nature and solutions are sought in a wide range of domains and instruments to achieve and manage it. The domains range from environmental sustainability (referring to natural environment) through organisational and business sustainability towards social sustainability. Concerning the instruments for sustainability, they range from traditional engineering and management methodologies towards “soft” instruments such as knowledge, learning, and creativity. The papers in this book address virtually whole sustainability problems space in a greater or lesser extent. However, although the uncertainty and/or turbulence, or in other words the dynamic properties, come from coupling of management, technology, learning, individuals, organisations and society, meaning that everything is at the same time effect and cause, we wanted to put the emphasis on business with the intention to address primarily companies and their businesses. Due to this reason, the main title of the book is “Business Sustainability 2.0” but with the approach of coupling Management, Technology and Learning for individuals, organisations and society in Turbulent Environments. Also, the notation“2.0” is to promote the publication as a step further from our previous publication – “Business Sustainability I” – as would be for a new version of software. Concerning the Second International Conference on BUSINESS SUSTAINABILITY, its particularity was that it had served primarily as a learning environment in which the papers published in this book were the ground for further individual and collective growth in understanding and perception of sustainability and capacity for building new instruments for business sustainability. In that respect, the methodology of the conference work was basically dialogical, meaning promoting dialog on the papers, but also including formal paper presentations. In this way, the conference presented a rich space for satisfying different authors’ and participants’ needs. Additionally, promoting the widest and global learning environment and participation, in accordance with the Conference's assumed mission to promote Proactive Generative Collaborative Learning, the Conference Organisation shares/puts open to the community the papers presented in this book, as well as the papers presented on the previous Conference(s). These papers can be accessed from the conference webpage (http://labve.dps.uminho.pt/bs11). In these terms, this book could also be understood as a complementary instrument to the Conference authors’ and participants’, but also to the wider readerships’ interested in the sustainability issues. The book brought together 107 authors from 11 countries, namely from Australia, Belgium, Brazil, Canada, France, Germany, Italy, Portugal, Serbia, Switzerland, and United States of America. The authors “ranged” from senior and renowned scientists to young researchers providing a rich and learning environment. At the end, the editors hope, and would like, that this book to be useful, meeting the expectation of the authors and wider readership and serving for enhancing the individual and collective learning, and to incentive further scientific development and creation of new papers. Also, the editors would use this opportunity to announce the intention to continue with new editions of the conference and subsequent editions of accompanying books on the subject of BUSINESS SUSTAINABILITY, the third of which is planned for year 2013.info:eu-repo/semantics/publishedVersio

Planning and Scheduling Optimization

Although planning and scheduling optimization have been explored in the literature for many years now, it still remains a hot topic in the current scientific research. The changing market trends, globalization, technical and technological progress, and sustainability considerations make it necessary to deal with new optimization challenges in modern manufacturing, engineering, and healthcare systems. This book provides an overview of the recent advances in different areas connected with operations research models and other applications of intelligent computing techniques used for planning and scheduling optimization. The wide range of theoretical and practical research findings reported in this book confirms that the planning and scheduling problem is a complex issue that is present in different industrial sectors and organizations and opens promising and dynamic perspectives of research and development

Survivable virtual topology design in optical WDM networks using nature-inspired algorithms

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Bilişim Enstitüsü, 2012Thesis (PhD) -- İstanbul Technical University, Institute of Informatics, 2012Günümüzde bilgisayar ağları hayatımızın önemli bir parçası ve ihtiyaç haline gelmiştir. İstediğimiz veriye, istediğimiz anda, daha hızlı, daha güvenli ve kesintisiz olarak erişme isteğimiz aslında ağ altyapısının nasıl tasarlanacağını belirlemektedir. Kullanıcıların istekleri sürekli artarken, teknolojik gelişmelerle birlikte yeni yöntem ve algoritmalarla bu istekleri karşılamanın yolları aranmaktadır. Ağdaki aktarım hızı, aktarım ortamından doğrudan etkilenmektedir; bugün uzak mesafelere en yüksek kapasiteli ve hızlı aktarımın yapılabileceği ortam ise fiberdir. Fiber optik ağlar, fiberin üstün özelliklerini (hız, düşük bit hata oranı, elektromanyetik ortamlardan etkilenmeme, düşük işaret zayıflaması, fiziksel dayanıklılık, ucuzluk, güvenlilik, vs.) en iyi kullanacak şekilde tasarlanan ağlardır. Günümüzde dünyadaki iletişim ağ altyapısı, omurga ağlardan erişim ağlarına kadar, hızla fiber optik ağlara dönüşmektedir. Optik ağların en önemli özelliklerinden biri veri aktarım hızıdır, tek bir fiberden teorik olarak 50 Tb/s veri aktarımı yapılabileceği hesaplanmaktadır. Bugün, lider iletişim firmaları 100 Gb/s ya da 1 Tb/s hızda veri aktarımı yapacak kanalllardan bahsedebiliyorsa, bu, fiziksel altyapı optik bir omurgadan oluştuğu içindir. Dalgaboyu bölmeli çoğullama (WDM) teknolojisi sayesinde bir fiber üzerinde aynı anda kurulabilecek kanal sayısı, günümüz teknolojisiyle yüzler mertebesine çıkabilmektedir. Dalgaboyu bölmeli çoğullama teknolojisi ile, optik aktarım birbiriyle çakışmayan dalgaboyu bantlarına bölünür ve her bir dalgaboyu istenen hızda çalışan, ışıkyolu olarak adlandırılan, bir iletişim kanalını destekler. Böylece, yakın gelecek için öngörülen çok yüksek hızlara çıkmadan bile, bir fiberden herbiri birkaç on Gb/s hızda çalışan yüz dolayında ışıkyolu geçebilmektedir. Bu kadar yüksek hızlarda veri aktarımı, özellikle her bir fiberinde çok sayıda kanalın taşındığı omurga ağlarda bir konuya büyük önem kazandırmaktadır: Hataya bağışıklık. En sık rastlanan hata olan, bir fiberin, herhangi bir nedenle kesilmesi (çoğunlukla inşaat makineleri tarafından, ya da doğal afetlerce), fiber tamir edilene kadar, her saniyede birkaç terabitlik veri kaybı anlamına gelecektir. Örnek olarak 10 km uzunlukta bir fiberin kopma sıklığı 11 yılda birdir. Omurga ağlarda yüzlerce, bazen binlerce, kilometrelik fiberler döşendiği gözönüne alındığında, böyle bir hata durumu için tedbir alınmaması düşünülemez. Optik ağ üzerindeki herhangi bir fibere zarar gelmesi demek bu fiber üzerinden yönlendirilmiş olan tüm ışıkyollarının kopması demektir. Her bir ışıkyolu üzerinden yüksek miktarda (40 Gb/s) veri aktarımı yapıldığından, böyle bir zarar ciddi veri kayıplarına neden olabilir. Temel olarak fiber kopmasına karşı geliştirilen iki yaklaşım vardır. Birinci yaklaşımda fiber üzerinden geçen her bir bağlantının, yani ışıkyolunun, yedek yollarla korunmasıdır. İkinci yaklaşım ise, özellikle birçok internet uygulamasına da uygun ve yeterli olacak şekilde, ışıkyollarının oluşturduğu sanal topolojinin bağlı kalmasının sağlanmasıdır. Bu ikinci yaklaşımda herbir ışıkyoluna ayrı ayrı yedek koruma yollarının atanması yerine, sanal topolojinin korunması dikkate alınarak, üst katmanların (paket katmanları) koruma mekanizmalarının devreye girebilmesi için gereken minimum koşulların sağlanması amaçlanmaktadır. Birinci yaklaşım belirli düzeylerde garantili bir koruma sağlarken yüksek miktarda ağ kaynağının atıl durmasına neden olmakta, dolayısıyla bu kadar üst düzey koruma gerektirmeyen uygulamalar için pahalı bir çözüm sunmaktadır. Son yıllarda özellikle dikkat çeken ikinci yaklaşım ise, daha ekonomik bir yöntemle iletişimin kopmaması garantisini vermekte, ancak daha yavaş bir düzeltme sağlamaktadır. Günümüzde birçok uygulama bağlantı kopmadığı sürece paket katmanının, yeni yol bulma gibi hata düzeltme mekanizmalarının devreye girmesi için gerekli olan, dakikalar mertebesindeki gecikmelere toleranslıdır (web dolaşımı, dosya aktarımı, mesajlaşma, uzaktan erişim gibi). Bu yaklaşım ilkine göre daha az ağ kaynağının atıl kalmasına neden olarak kullanıcıya daha ekonomik hizmet verilmesini sağlayacaktır. Bu çalışmada üzerinde durduğumuz hataya bağışık sanal topoloji tasarımı problemi de bu ikinci yaklaşımı benimsemektedir. Hataya bağışık sanal topoloji tasarımı problemi kendi içinde dört alt probleme ayrılmaktadır: ışıkyollarının belirlenmesi (sanal topolojiyi oluşturma), bu ışıkyollarının herhangi bir fiber kopması durumunda bile sanal topolojinin bağlı kalmasını sağlayacak sekilde fiziksel topoloji üzerinde yönlendirilmesi, dalgaboyu atanması, ve paket trafiğinin yönlendirilmesi. Bu alt problemler ayrı ayrı çözülebilir. Ancak, bunlar bağımsız problemler değildir ve bunları tek tek çözmek elde edilen çözümün kalitesinin çok düşük olmasına neden olabilir. Bununla birlikte, hataya bağışık sanal topoloji tasarımı problemi NP-karmaşıktır. Karmaşıklığı nedeniyle bu problemin, gerçek boyutlu ağlar için, klasik optimizasyon teknikleriyle kabul edilebilir zamanda çözülmesi mümkün değildir. Bu çalışmada, fiziksel topolojinin ve düğümler arası paket trafiği yoğunluğunun bilindiği durumlar için, hataya bağışık sanal topoloji tasarımı problemi bütün halinde ele alınmaktadır. Tezin ilk aşamasında, hataya bağışık sanal topoloji tasarımı probleminin alt problemi olan hataya bağışık sanal topoloji yönlendirmesi problemi ele alınmıştır. Verilen bir sanal topoloji için en az kaynak kullanarak hataya bağışık yönlendirme yapmak için iki farklı doğa-esinli algoritma önerilmektedir: evrimsel algoritmalar ve karınca kolonisi optimizasyonu. Öncelikle önerilen algoritmaların problem için uygun parametre kümesi belirlenmiş, daha sonra, algoritmaların başarımını ölçmek için, deneysel sonuçlar tamsayı doğrusal programlama (ILP) ile elde edilen sonuçlarla karşılaştırılmışır. Sonuçlar göstermektedir ki; önerdiğimiz iki algoritma da, tamsayı doğrusal programlama ile uygun bir çözüm bulunamayan büyük ölçekli ağlar için dahi, problemi çözebilmektedir. Bunun yanında, doğa-esinli algoritmalar çok daha az CPU zamanı ve hafıza kullanmaktadır. Elde edilen çözüm kalitesi ve çözüm için kullanılan CPU zamanının kabul edilebilir düzeyde olması, her iki doğa-esinli algoritmanın da gerçek boyutlu ağlar için kullanılabileceğini doğrulamaktadır. İkinci aşamada, hataya bağışık sanal topoloji tasarımı problemini bir bütün halinde çözmek için dört farklı üst-sezgisel yöntem önerilmektedir. Önerilen üst-sezgisel yöntemler alt seviyedeki sezgiselleri seçme asamasında dört farklı yöntem kullanmaktadır: evrimsel algoritmalar, benzetimli tavlama, karınca kolonisi optimizasyonu ve uyarlamalı yinelenen yapıcı arama. Deneysel sonuçlar tüm üst-sezgisel yöntemlerin hataya bağışık sanal topoloji tasarımı problemini çözmede başarılı olduğunu göstermektedir. Ancak, karınca kolonisi optimizasyonu tabanlı üst-sezgisel diğerlerine göre daha üstün sonuçlar vermektedir. Işıkyolları üzerindeki trafik akışını dengelemek için, karınca kolonisi optimizasyonu tabanlı üst-sezgisele akış deviasyonu yöntemi de eklenmiştir. Literatürde hataya bağışık sanal topoloji tasarımı problemini ele alan tüm çalışmalar çift fiber kopması durumunu gözardı etmektedir. Bu çalışmada, önerdiğimiz üst-sezgisel yöntemin başarımını hem tek hem de çift fiber kopması durumları için değerlendirdik. Önerdiğimiz yöntem çoklu fiber kopması durumları için çok kolay şekilde adapte edilebilmektedir. Tek yapılması gereken hataya bağışıklık kontrolünü yapan yordamın değiştirilmesidir. Deneysel sonuçlar göstermiştir ki, önerdiğimiz karınca kolonisi optimizasyonu tabanlı üst-sezgisel hataya bağışık sanal topoloji tasarımı problemini hem tek hem de çift fiber kopması durumları için kabul edilebilir bir sürede çözebilmektedir. Üst-sezgisel yöntemlerin hataya bağışık sanal topoloji tasarımı çözmedeki başarımını değerlendirebilmek amacıyla, karınca kolonisi optimizasyonu tabanlı üst-sezgiselle elde edilen sonuçlar, literatürde bu problem için önerilmiş başka bir yöntemle karşılaştırılmıştır. Sonuçlar üst-sezgisel yöntemlerin, çok daha az CPU zamanı kullanarak, problem için daha kaliteli çözümler verdiğini göstermektedir.Today, computer networking has become an integral part of our daily life. The steady increase in user demands of high speed and high bandwidth networks causes researchers to seek out new methods and algorithms to meet these demands. The transmission speed in the network is directly affected by the transmission medium. The most effective medium to transmit data is the fiber. Optical networks are designed for the best usage of the superior properties of the fiber, e.g. high speed, high bandwidth, low bit error rate, low attenuation, physical strength, cheapness, etc. The world's communication network infrastructure, from backbone networks to access networks, is consistently turning into optical networks. One of the most important properties of the optical networks is the data transmission rate (up to 50 Tb/s on a single fiber). Today, with the help of the wavelength division multiplexing (WDM) technology, hundreds of channels can be built on a single fiber. WDM is a technology in which the optical transmission is split into a number of non-overlapping wavelength bands, with each wavelength supporting a single communication channel operating at the desired rate. Since multiple WDM channels, also called lightpaths, can coexist on a single fiber, the huge fiber bandwidth can be utilized. Any damage to a physical link (fiber) on the network causes all the lightpaths routed through this link to be broken. Since huge data transmission (40 Gb/s) over each of these lightpaths is possible, such a damage results in a serious amount of data loss. Two different approaches can be used in order to avoid this situation: 1. Survivability on the physical layer, 2. Survivability on the virtual layer. The first approach is the problem of designing a backup link/path for each link/path of the optical layer. The second approach is the problem of designing the optical layer such that the optical layer remains connected in the event of a single or multiple link failure. While the first approach provides faster protection for time-critical applications (such as, IP phone, telemedicine) by reserving more resources, the second approach, i.e. the survivable virtual topology design, which has attracted a lot of attention in recent years, aims to protect connections using less resources. The problem that will be studied in this project is to develop methods for survivable virtual topology design, that enables effective usage of the resources. Survivable virtual topology design consists of four subproblems: determining a set of lightpaths (forming the virtual topology), routing these lightpaths on the physical topology (routing and wavelength assignment (RWA) problem), so that any single fiber cut does not disconnect the virtual topology (survivable virtual topology mapping), assigning wavelengths, and routing the packet traffic. Each of these subproblems can be solved separately. However, they are not independent problems and solving them one by one may degrade the quality of the final result considerably. Furthermore, the survivable virtual topology design is known to be NP-complete. Because of its complexity, it is not possible to solve the problem optimally in an acceptable amount of time using classical optimization techniques, for real-life sized networks. In this thesis, we solve the survivable virtual topology design problem as a whole, where the physical topology and the packet traffic intensities between nodes are given. In the first phase, we propose two different nature inspired heuristics to find a survivable mapping of a given virtual topology with minimum resource usage. Evolutionary algorithms and ant colony optimization algorithms are applied to the problem. To assess the performance of the proposed algorithms, we compare the experimental results with those obtained through integer linear programming. The results show that both of our algorithms can solve the problem even for large-scale network topologies for which a feasible solution cannot be found using integer linear programming. Moreover, the CPU time and the memory used by the nature inspired heuristics is much lower. In the second phase, we propose four different hyper-heuristic approaches to solve the survivable virtual topology design problem as a whole. Each hyper-heuristic approach is based on a different category of nature inspired heuristics: evolutionary algorithms, ant colony optimization, simulated annealing, and adaptive iterated constructive search. Experimental results show that, all proposed hyper-heuristic approaches are successful in designing survivable virtual topologies. Furthermore, the ant colony optimization based hyper-heuristic outperforms the others. To balance the traffic flow over lightpaths, we adapt a flow-deviation method to the ant colony optimization based hyper-heuristic approach. We explore the performance of our hyper-heuristic approach for both single and double-link failures. The proposed approach can be applied to the multiple-link failure problem instances by only changing the survivability control routine. The experimental results show that our approach can solve the problem for both single-link and double-link failures in a reasonable amount of time. To evaluate the quality of the HH approach solutions, we compare these results with the results obtained using tabu search approach. The results show that HH approach outperforms tabu search approach both in solution quality and CPU time.DoktoraPh