The implicit assumption in conventional inventory models is that the stored products maintain the same utility forever, i.e., they can be stored for an infinite period of time without losing their value or characteristics. However, generally speaking, almost all products experience some sort of deterioration over time. Some products have very small deterioration rates, and henceforth the effect of such deterioration can be neglected. Some products may be subject to significant rates of deterioration. Fruits, vegetables, drugs, alcohol and radioactive materials are examples that can experience significant deterioration during storage. Therefore the effect of deterioration must be explicitly taken into account in developing inventory models for such products. In most existing deteriorating inventory models, time is treated as a continuous variable, which is not exactly the case in practice. In real-life problems time factor is always measured on a discrete scale only, i.e. in terms of complete units of days, weeks, etc. In this research, we present several discrete-in-time inventory models and identify optimal ordering policies for a single deteriorating product by minimizing the expected overall costs over the planning horizon. The various conditions have been considered, e.g. periodic review, time-varying deterioration rate, waiting-time-dependent partial backlogging, time-dependent demand, stochastic demand etc. The objective of our research is two-fold: (a) To obtain optimal order quantity and useful insights for the inventory control of a single deteriorating product over a discrete time horizon with deterministic demand, variable deterioration rates and waiting-time-dependent partial backlogging ratios; (b) To identify optimal ordering policy for a single deteriorating product over a finite horizon with stochastic demand and partial backlogging. The explicit ordering policy will be developed for some special cases. Through computational experiments and sensitivity analysis, a thorough and insightful understanding of deteriorating inventory management will be achieved.

No description available.

<p> <p>&nbsp / </p> </p> <p align="left">The underlying theme of this thesis is identification, classification, detection and prediction of cellular network faults using state of the art technologies, methods and algorithms.</p>

Les centres de données verts de dernière génération ont été conçus pour une consommation optimisée et une meilleure qualité du niveau de service SLA. Cependant,ces dernières années, le marché des centres de données augmente rapidement,et la concentration de la puissance de calcul est de plus en plus importante, ce qui fait augmenter les besoins en puissance électrique et refroidissement. Un centre de données est constitué de ressources informatiques, de systèmes de refroidissement et de distribution électrique. De nombreux travaux de recherche se sont intéressés à la réduction de la consommation des centres de données afin d'améliorer le PUE, tout en garantissant le même niveau de service. Certains travaux visent le dimensionnement dynamique des ressources en fonction de la charge afin de réduire le nombre de serveurs démarrés, d'autres cherchent à optimiser le système de refroidissement qui représente un part important de la consommation globale.Dans cette thèse, afin de réduire le PUE, nous étudions la mise en place d'un système autonome d'optimisation globale du refroidissement, qui se base sur des sources de données externes tel que la température extérieure et les prévisions météorologiques, couplé à un module de prédiction de charge informatique globale pour absorber les pics d'activité, pour optimiser les ressources utilisés à un moindre coût, tout en préservant la qualité de service. Afin de garantir un meilleur SLA, nous proposons une architecture distribuée pour déceler les anomalies de fonctionnements complexes en temps réel, en analysant de gros volumes de données provenant des milliers de capteurs du centre de données. Détecter les comportements anormaux au plus tôt, permet de réagir plus vite face aux menaces qui peuvent impacter la qualité de service, avec des boucles de contrôle autonomes qui automatisent l'administration. Nous évaluons les performances de nos contributions sur des données provenant d'un centre de donnée en exploitation hébergeant des applications réelles. / Next-generation green datacenters were designed for optimized consumption and improved quality of service level Service Level Agreement (SLA). However, in recent years, the datacenter market is growing rapidly, and the concentration of the computing power is increasingly important, thereby increasing the electrical power and cooling consumptions. A datacenter consists of computing resources, cooling systems, and power distribution. Many research studies have focused on reducing the consumption of datacenters to improve the PUE, while guaranteeing the same level of service. Some works aims the dynamic sizing of resources according to the load, to reduce the number of started servers, others seek to optimize the cooling system which represents an important part of total consumption. In this thesis, in order to reduce the PUE, we study the design of an autonomous system for global cooling optimization, which is based on external data sources such as the outside temperature and weather forecasting, coupled with an overall IT load prediction module to absorb the peaks of activity, to optimize activere sources at a lower cost while preserving service level quality. To ensure a better SLA, we propose a distributed architecture to detect the complex operation anomalies in real time, by analyzing large data volumes from thousands of sensors deployed in the datacenter. Early identification of abnormal behaviors, allows a better reactivity to deal with threats that may impact the quality of service, with autonomous control loops that automate the administration. We evaluate the performance of our contributions on data collected from an operating datacenter hosting real applications.

Cette thèse aborde le problème de tournées de véhicules périodiques (PVRP) lorsqu'il est appliqué au transport de marchandises convoitables. Des contraintes spécifiques relatives à la sécurité du convoi doivent être définies.Le problème de tournées de véhicules périodiques avec dispersion des instants de service (PVRPTS) est alors décrit puis modélisé mathématiquement. Le but est de servir un ensemble de clients sur plusieurs jours en respectant un degré de variation définit dans les heures de service. Le modèle obtenu est discuté et deux heuristiques constructives sont proposées et évaluées pour sa résolution.Une recherche locale itérée avec redémarrages (MS-ILS) est proposée pour ce problème. Les résultats obtenus montrent que cette méthode surpasse les deux précédentes sur toutes les instances de test. Elle est ensuite évaluée sur un problème plus classique de la littérature : le problème de tournées de véhicules avec fenêtres horaires souples (VRPSTW) et s'avère très compétitive, produisant de nouvelles meilleures solutions.La MS-ILS est ensuite transposée au problème de tournées de véhicules régulières (ConVRP). Contrairement au PVRPTS, il s'agit dans le ConVRP de servir régulièrement des clients aux demandes intermittentes. La méthode montre une flexibilité remarquable et produit de bons résultats.Pour finir, les développements effectués chez Nexxtep Technologies sont présentés. Ils comprennent la conception d'un logiciel commercial pour l'optimisation de tournées de véhicules et l'implémentation des méthodes développées / This thesis is dedicated to the periodic vehicle routing problem when applied to the transportation of valuable goods. Specifics constraints have to be defined to ensure the security of the convoy.The periodic vehicle routing problems with time spread constraints on services (PVRPTS) is defined and a mathematical model is given. The goal is to serve a set of customers over several days such that their visit times differ by a minimum amount. The depicted model is discussed and two constructive heuristics are designed and assessed.A Multi-start iterated local search (MS-ILS) is proposed to solve this problem. The results shows that the method outperform the two previous heuristics. For the sake of comparison with previous approaches, the MS-ILS is evaluated on a more classical problem : the vehicle routing problem with soft time windows (VRPSTW). The method proves to be very competitive, producing new best known solutions.The MS-ILS is then adapted to solve the consistent vehicle routing problem (ConVRP). Unlike the PVRPTS, the goal of the ConVRP is to deliver customers with intermittent demands with regularity in terms of service times and drivers. The method demonstrate his flexibility and produce good results. Finally, the developments performed at Nexxtep Technologies are depicted. They encompass commercial-software design and implementation of the proposed methods

Syfte– Syftet med denna studie var att finna ett klassificeringsverktyg som kan underlätta beslutsfattande vid reservdelsuppläggning. För att besvara syftet formuleradestre frågeställningar;   Vilket analysverktyg kan användas för att systematiskt klassificera reservdelar i olika    grupper? Hur kan de klassificerade grupperna nyttjas vid reservdelsuppläggning?  Hur kan efterfrågan prognostiseras för de olika klassificerade grupperna med hänsyn till servicenivå? Metod– Studien bedrevs deduktivt genom teoribyggande, med både en empiriskt fallstudie och analytisk konceptuell inriktning. De metoder som studien använts sig av är; litteraturstudier, intervjuer och insamling från dokumentstudien. Litteraturstudien har varit inom områdena; reservdelsklassificering och prognostisering.  Resultat– Studiens resultat är att det krävs en multiklassificeringsmodell för att systematiskt klassificera reservdelar på grund av den komplexa naturen av reservdelshanteringen. Klassificeringsmodellen kan sedan utnyttjas till flera ändamål. De användningsområden som studien funnit är; hjälp vid bestämning av servicenivå, hjälp med val av prognostiseringsmetod för reservdelsgrupperna samt att finna reservdelar som har en skiftande efterfrågetrend.    Implikationer– Klassificeringsmodellen ämnar sig till att underlätta företags reservdelsuppläggning. Med hjälp av modellen ska fallföretaget lättare kunna ta beslut så som vilken servicenivå och prognosmetod som kan användas för deras reservdelar. Begränsningar–  Den här studiens begränsning är att bara ett fallföretag studerades på grund av tidsbegränsningen. Detta medförde att modellen som anpassades blev företagsspecifik och rekommenderas att valideras på andra företag.  Nyckelord– Klassificering, Reservdelsklassificering, Beslutstöd, Prognostisering, Reservdelsprognostisering, Servicenivå / Purpose–The purpose of this study was to find a classification tool that can ease the decision-making process of spare parts planning and forecasting. To accomplish this, three research questions were formulated; Which analysis tools can be used for a systematic classification of spare parts into different groups? How can the classified groups be used when planning and forecasting spare parts? How can the forecasting be done for the different classified groupsconsidering thecustomer service level?  Method– The study was deductively through theory-building, with both an empirical case study and analytical conceptual approach. The methods used were; litterateur research, interviews and collection of secondary data. The litterateur research has been conducted in the areas; spare parts classification and forecasting.  Findings– The finding of this study was that a multi criteria method is needed for a systematic classification of spare parts, because of the complex nature of spare part handling. The classification model can then be used for multiple tasks. The tasks that this study found were; help in deciding the customer service level, help in choosing forecast method for the different spare part groups and finding the spare parts that have shifted in demand trend. Implications– The classification model intends to ease companies spare parts planning and forecasting process. With help from the model the case company should have a more effective process now in choosing which customer service level and forecasting method to use for their spare part.   Limitations– This studies limitation was that only one case company was studied because of time constraints. This makes the modified model very company specific and needs to be further validated on other companies.  Keywords– Classification, Spare parts classification, Decision support, Forecasting, Spare parts forecasting, customer service level

Le Cloud Computing est en plein essor, grace a ses divers avantages, telsl'elasticite, le cout, ou encore son importante exibilite dans le developpementd'applications. Il demeure cependant des problemes en suspens, lies auxperformances, a la disponibilite, la fiabilite, ou encore la securite. De nombreusesetudes se focalisent sur la fiabilite et les performance dans les servicesdu Cloud, qui sont les points critiques pour le client. On retrouve parmicelles-ci plusieurs themes emergents, allant de l'ordonnancement de tachesau placement de donnees et leur replication, en passant par la tolerance auxfautes adaptative ou a la demande, et l'elaboration de nouveaux modeles defautes.Les outils actuels evaluant la fiabilite des services du Cloud se basent surdes parametres simplifies. Ils ne permettent pas d'analyser les performancesou de comparer l'efficacite des solutions proposees. Cette these aborde precisement ce probleme en proposant un modele d'environnement complet detest destine a evaluer la fiabilite et les performances des services de CloudComputing. La creation d'outils de tests destines a l'evaluation de la fiabiliteet des performances des services du Cloud pose de nombreux defis, en raisonde la grande quantite et de la complexite des donnees traitees par ce genrede services. Les trois principaux modeles de Cloud Computing sont respectivement:Infrastructure en tant que Service (IaaS), Plate-forme en tant queService (PaaS) et Logiciel en tant que Service (SaaS).Dans le cadre de cettethese, nous nous concentrons sur le modele PaaS. Il permet aux systemesd'exploitation ou aux intergiciels d'etre accessibles via une connexion internet.Nous introduisons une architecture de test generique, qui sera utiliseepar la suite lors de la creation d'outils de tests, destines a l'evaluation de lafiabilite et de la performance. / Cloud computing models are attractive because of various benefits such asscalability, cost and exibility to develop new software applications. However,availability, reliability, performance and security challenges are still not fullyaddressed. Dependability is an important issue for the customers of cloudcomputing who want to have guarantees in terms of reliability and availability.Many studies investigated the dependability and performance of cloud services,ranging from job scheduling to data placement and replication, adaptiveand on-demand fault-tolerance to new fault-tolerance models. However, thead-hoc and overly simplified settings used to evaluate most cloud service fault toleranceand performance improvement solutions pose significant challengesto the analysis and comparison of the effectiveness of these solutions.This thesis precisely addresses this problem and presents a benchmarkingapproach for evaluating the dependability and performance of cloud services.Designing of dependability and performance benchmarks for a cloud serviceis a particular challenge because of high complexity and the large amount ofdata processed by such service. Infrastructure as a Service (IaaS), Platform asa Service (PaaS) and Software as a Service (SaaS) are the three well definedmodels of cloud computing. In this thesis, we will focus on the PaaS modelof cloud computing. PaaS model enables operating systems and middlewareservices to be delivered from a managed source over a network. We introduce ageneric benchmarking architecture which is further used to build dependabilityand performance benchmarks for PaaS model of cloud services.

Uppsatsen undersöker hur Emballator Växjöplast prioriterar och resonerar kring aspekterna volymutnyttjande, plocktid, säkerhet, kapitalbindning och servicenivå vid optimering av deras färdigvarulager. Författarna kom fram till följande slutsats: Fallföretaget prioriterar säkerhet högst för att skydda individen Servicenivå prioriteras efter säkerhet då de arbetar kundfokuserat. Efter servicenivå prioriteras volymutnyttjande för att minska sin externlagring. Plocktid prioriteras efter volymutnyttjande där målsättningen är att undvika nyanställningar. Sist prioriteras kapitalbindning då denna inte är fokus för logistikfunktionen.   Vidare undersöker författarna hur en multi-criteria optimization av aspekterna vid optimering av färdigvarulagret kan gå till. Författarna kommer fram till följande slutsatser: The main criteria method är bäst lämpad optimeringsmetod. Volymutnyttjande ska minimeras givet att resterande aspekter uppfyller respektive bivillkor. De flesta förvaringsmetoder och artikelplaceringar uppfyller aspekternas bivillkor Bäst lämpad förvaringsmetod och artikelplacering grundas därför på vilken som möjliggör bäst volymutnyttjande. Slutligen utvärderas Emballator Växjöplasts nuvarande färdigvarulager sett till aspekterna utifrån analysen för frågeställning 2. Här presenteras även kortsiktiga och långsiktiga förbättringsförslag. Författarna kom fram till följande slutsats: Deras nuvarande förpackning, förvaringsmetod samt artikelplacering tillgodoser respektive bivillkor men kan förbättras sett till the main criteria, volymutnyttjande. Ett kortsiktigt förbättringsförslag genom att utföra en liknande artikelplacering på bättre sätt kan upp till 38-57 fler pallar rymmas på färdigvarulagret. Ett långsiktigt förbättringsförslag genom att kombinera traditionella pallställage och drive-through eller push-back-hyllor, kan totala antal pallplatser på färdigvarulagret öka med 18,4 %. / The essay examines how Emballator Växjöplast prioritize and reason among the aspects safety, service level, utilization rate, order picking time and capital tied up in inventory when optimizing their finished goods warehouse. The authors came to the following conclusion: Firstly, they prioritize safety the highest to protect the individuals within the warehouse. Service level is prioritized secondly because they operate with a customer focus. After service level utilization rate is prioritized to lower their need for external storage. Order picking time is prioritized after utilization rate with the goal to avoid the need for employing more operators within the warehouse. Lastly capital tied up in inventory is prioritized because the aspect is not in focus for the logistics department.   Moreover, the authors investigate how multi-criteria optimization as an optimization method can be used when optimizing a finished goods warehouse considering several contradictive aspects and the conclusion is: The main criteria method is best suited in optimization method. Utilization rate is the main criteria and the other aspects are constraints. The majority of storage systems and storage assignment policy are within the constraints. The best storage systems and storage assignment policy is therefore mainly determined by the main criteria.   Lastly a discussion regarding the finished goods warehouse is held and both short term and long term improvements regarding the aspects are presented. The conclusions made by the authors are as follows: Their current packaging, storage systems and storage assignment policy is sufficient in terms of the different constraints but the main criteria can be improved. Short term improvements are to use a similar storage assignment policy in a better way and enable room for 38-57 more pallets in the finished goods warehouse. Long term improvements are to improve both storage assignment policy and the storage system. By combining traditional racks with some other storage system such as drive-through or push-back-shelves the number of pallets that can fit within the warehouse can increase by 18,4%.

A economia globalizada e os avanços tecnológicos propiciaram um novo modelo de Outsourcing de Tecnologia de Informação (TI): os provedores de serviços de aplicativos (ASP - Application Service Providers). As discussões a respeito de ASP intensificaram-se nos três últimos anos, com a proposta de comercialização do software como um serviço. Quanto maior a interdependência da área de TI com as metas de negócios das organizações, maior a ênfase dada à satisfação das expectativas do cliente quanto aos serviços prestados pelos provedores. No mercado, têm-se adotado os acordos dos níveis de serviços (SLA - Service Level Agreements) como mecanismo de controle das atividades de outsourcing. Porém, essa adoção é nova e imatura, e a literatura é escassa. Tanto os provedores quanto os cliente sentem a necessidade por estruturas de implantação semelhantes às de SLA. Essa carência é ressaltada no caso dos modelos ASP. Propondo-se a contribuir com a compressão do modelo ASP e de SLA para ASP, apresenta-se uma pesquisa exploratória das características desse modelo com SLA, de modelos de qualidade de serviços de outsourcing e finalmente de considerações que devem ser feitas para garantir a qualidade dos serviços ASP, empregando-se os SLA. / The global economy and technological advances propitiated a new model of Information Technology (IT) Outsourcing: the Application Service Providers - ASP. Discussions regarding ASP became more frequent in the last three years because of the new approach of selling software as a service. As the interdependency between the IT area and the business goals of organizations becomes greater, the emphasis on fulfilling the client\'s expectations regarding service rendered by providers becomes stronger. In the market, Service Level Agreements - SLA have been adopted as control mechanisms of outsourcing activities. However, this adoption is new and immature, and the literature on the matter is scarce. Providers and clients feel the need for implementation structures similar to SLA\'s. In lhe case of ASP models, this necessity is emphasized mainly due to the lack of conceptual information on the ASP model. In order to better comprehend lhe ASP and the SLA models for ASP, I am presenting an exploratory research about the characteristics of the new approach with SLA models, outsourcing models of service quality and considerations, which must be carried out to ensure quality of ASP services employing SLA.

With Cloud Computing becoming a popular term on the Information Technology (IT) market, security and accountability has become important issues to highlight. In our research we review these concepts by focusing on security risks with Cloud Computing and the associated services; Software, Platform and Infrastructure (SPI) and connecting them with a social study of trust. The method that was conducted during our research was reviewing secondary literature, interviewing different experts regarding Cloud Computing and relating standards already established by ENISA, NIST, and CSA to the interviews. The result of this study shows connections between the specific SPIs, both how they compare, but also how they differ. In the end we were also able to rank the top security risks from interviews with experts and see which SPI could be the most insecure one and  what countermeasures could be applied. This was further related to trust and Service Level Agreement (SLA) in Cloud Computing to show how the security risks we discuss are related to these two specific areas. By highlighting this we wanted to present useable information for both clients and providers in how to create a better Cloud Computing environment.