Les disruptions sont des pertes violentes et très rapides (environ 20 ms) du confinement des plasmas de tokamak qui peuvent conduire à des endommagements de la structure du tokamak. Elles génèrent des charges thermiques sur les composants face au plasma, des forces électromagnétiques dans les structures de la machine et produisent des électrons découplés relativistes pouvant perforer l'enceinte à vide. Pour des futurs réacteurs, il sera indispensable d'amortir ces effets. L'injection massive de gaz est une des méthodes proposées dans ce but. Son étude expérimentale et numérique est l'objet de la thèse. Des expériences menées sur les tokamaks Tore Supra et JET ont montré que l'injection de gaz légers comme l'hélium empêchaient la production d'électrons découplés, au contraire des gaz plus lourds. Les gaz légers sont en effet capables d'accroître suffisamment la densité du plasma pour empêcher la création de ces électrons. En revanche, les gaz lourds permettent de dissiper par rayonnement et de façon plus bénigne une partie de l'énergie thermique du plasma. Tous les gaz diminuent les forces électromagnétiques. Des mélanges de gaz ont également été testés avec succès pour profiter des avantages des deux types de gaz. La pénétration du gaz dans le plasma semble liée à des instabilités MHD augmentant le transport radial du gaz ionisé vers le centre, mais empêchant la propagation des neutres au-delà d'une surface critique. Des simulations d'injections massives ont été réalisées avec le code 3D MHD Jorek, en y ajoutant un modèle de fluide neutre. Les résultats montrent que la croissance des instabilités MHD est plus rapide lorsque de grandes quantités de gaz sont injectées et que les surfaces rationnelles sont successivement ergodisées lors de la pénétration du front de densité dans le plasma, conformément aux observations expérimentales.

Disruptions to the freight transportation system are costly due to freight's critical relationship to economic productivity. This research will analyze the current methods of estimating the economic impacts of disruptions to the freight transportation system. A review of existing literature will be conducted with the intent of finding methods that address different types of disruptions and impacts. Due to varying economic scopes and disruptions studied, the results will likely indicate a broad range of methodologies and trends. The results will be used to better understand the different approaches taken when quantifying the economic impacts of disruptions and therefore enable more informed policy, regulation and investment.

Independent de la performance remarquable accomplie par la logistique d’aujourd’hui, les réseaux actuels sont majoritairement dédiés à un acteur et donc très peu interconnectés. Cette fragmentation conduit une difficulté de mutualisation des flux et dès lors à une efficacité limitée. Ces organisations dédiées et hétérogènes sont de plus en plus challengées par les nouveaux défis d’aujourd’hui posés à l’efficacité, l’efficience et la résilience. Pour répondre à cet antagonisme, un innovant concept logistique - l’Internet Physique (PI) - a été proposé. Dans ce système, les infrastructures et les moyens de transport peuvent être organisés de façon dynamique et attribués à court ou à long terme en fonction des besoins. Par conséquent, les décisions des opérations logistiques peuvent être prises de façon dynamique, agile, et donc de manière plus optimale. Cette thèse concentre les perspectives de PI concernant la gestion de stocks et du transport par rapport aux défis de l’efficacité et de la résilience.Comme l’étude de l’efficacité de PI par rapport au transport a été déjà effectuée, le premier objectif de cette recherche est d’explorer les potentiels de l’interconnexion des réseaux dans la gestion de stocks, qui n’a par encore été adressé. À cette fin, nous examinons d'abord les trois nouvelles pratiques apportées par PI : 1) les stocks distribués à proximité des clients finaux; 2) le transbordement de stocks entre les hubs; 3) de multiples options dynamiques de sélection de la source pour chaque commande. Deux modèles de gestion de stocks correspondants sont proposés. Cette étude sert de guide pour des décisions de stockage pour les vendeurs dans un tel système logistique ouvert.Après l’analyse d’efficacité de PI, la deuxième partie de cette thèse concerne la résilience des modèles de stockage et de transport dans PI confrontés à des interruptions dans la chaîne logistique. On a étendu les modèles de stockage et de transport avec interruptions imprévisibles dans les infrastructures telles que l’usine ou les hubs. Des stratégies différentes sont développées pour atténuer les risques de perturbation des flux. Des études numériques sont effectuées pour évaluer la performance des modèles proposés.En résumé, cette recherche est la première qui étudie le potentiel de l’Internet Physique pour la gestion de stock et la résilience de ce système. D’après les résultats, il n’y a aucun doute que le PI change le design de chaîne logistique d’aujourd’hui et améliore la performance de gestion de logistique à la fois en efficience et en résilience. / Irrespective of significant performance achieved, today’s logistics networks are overwhelmingly dedicated to an actor and therefore poorly interconnected. This fragmentation exhibits inevitable inefficiency and needs to be changed in respond to today’s new arising challenges in efficiency and resilience. To solve this antagonism, an innovative concept - Physical Internet (PI) - has been proposed which is a fully interconnected, open, dynamic logistics system. In such a system, the facilities and means of transportation can be dynamically organized and allocated in the short-term or long-term according to the economic environment. As a result, decisions can be made dynamically, agilely, and thus optimally. This thesis studies the perspectives of the PI to inventory management and transportation regarding the challenges in efficiency and resilience.As the efficiency of the PI to transportation has been carried out in literature, the first objective of this thesis is to explore the potentials of the PI to inventory management. To this end, we firstly qualitatively examine the new practices brought by the PI and conclude three main characteristics: 1) Distributed stocks near end customers; 2) Transshipment of inventories; and 3) multiple dynamic source options. Corresponding inventory models and solutions are proposed and evaluated with numerical experiments in Fast Moving Consumer Goods (FMCG). This part of study gives a guideline for the vendors applying the PI to make inventory decisions in such an open logistic system.The second objective is to analyze the resilience of the proposed PI enabled inventory and transportation model confronted to disruptions. The proposed inventory and transportation model are extended with different disruptions at facilities including plants and hubs. Different disruption strategies are developed. Numerical studies in FMCG are carried out.In a word, this research investigates the inventory management in the PI and the resilience of PI enabled logistics models. It is the first time such a work is done and it should be upfront. From the results of studies, there is no doubt that the PI changes today’s supply chains design and improve the performance of supply chain management both in efficiency, effectiveness and resilience.

O consumo de drogas resulta em consequências para o indivíduo tanto no âmbito social quanto no de saúde. Conhecimentos sobre comportamentos de saúde dos usuários de drogas tornam-se relevante para melhor compreender esse grupo. O estudo teve por objetivo avaliar as propriedades psicométricas do Questionário Comportamentos de Saúde em usuários de substâncias psicoativas. Trata-se de um estudo quantitativo do tipo descritivo. O estudo foi desenvolvido no Centro de Atenção Psicossocial - Álcool e Drogas de Ribeirão Preto, SP, Brasil. A amostra foi composta por 140 usuários do serviço. O instrumento utilizado foi composto por: Informações sociodemográficas, Escala de Severidade da Dependência de Drogas, Severity Alcohol Dependence Data e o Questionário Comportamentos de Saúde. Utilizou-se a análise descritiva dos dados e a validade de construto por meio da análise fatorial. Para a consistência interna do instrumento e de seus fatores utilizou-se o coeficiente alfa de Cronbach. A amostra caracteriza-se predominantemente por usuários do sexo masculino, adultos, solteiros, cor da pele branca, com baixo nível de escolaridade. A maior parte deles já esteve em tratamento e a busca por atendimento ocorreu voluntariamente ou por meio de seus familiares. A droga de maior consumo foi o crack. Os usuários, em sua maioria apresentaram níveis graves de severidade da dependência alcoólica e também da dependência de cocaína e crack. A maconha foi a droga de primeiro uso. A análise fatorial resultou em um modelo composto por oito fatores, sendo: comportamentos sexuais seguros; autocuidado com poluição ambiental; saúde; atividades físicas; autocuidado com alimentação; alimentação saudável; automedicação e consumo de bebidas alcoólicas, além da segurança motorizada. Os coeficientes de alfa de Cronbach mostraram-se satisfatórios com índices acima de 0,50 para os fatores, e 0,82 para o questionário Comportamentos de Saúde global. Os resultados confirmam a confiabilidade do Questionário Comportamentos de Saúde na versão brasileira para sua aplicabilidade em usuários de substâncias psicoativas. / Drugs consumption results in consequences for the individual both in the social as in health environment. Knowledge about health behaviors of drug users becomes important to better understand this group. The study aimed to evaluate the pschycometric propriety of the health behavior questionnaires in users of psychoactive substances. It is about a quantitative descriptive study. The study was conducted at the Center of Psychosocial Care - Alcohol and Drugs from Ribeirão Preto, SP, Brazil. The sample consisted of 140 service users. The instrument used was composed of: Sociodemographic Information, Severity of Dependence Scale, Severity Alcohol Dependence Data and the Health Behaviors Questionnaire. It has been used a descriptive analyses of the data and construct validity using factor analysis. For the internal consistency of the instrument and it\'s factors it was used the Cronbach Alpha Coefficient. The sample is characterized predominantly by male users, adults, singles, white color (Caucasian) with a low educational level. Most of them have already been on treatment and the search for it happened voluntarily or through their families. The most consumed drug was crack. The majority of users presented serious levels of severity of alcohol dependence and also the dependence of cocaine and crack. Cannabis was the first used drug. Factor analysis resulted in a model composed of eight factors, as follows: safe sexual behavior; self care with environmental pollution; health; physical activity; self care with food; healthy eating; self medication and alcohol consumption, as well as motorized safety. The Cronbach\'s alpha coefficients were satisfactory with indexes above 0.50 for the factors, and 0.82for the global Health Behaviors Questionnaire. The results confirm the reliability of the Health Behaviors Questionnaire in Brazilian version forits applicability in users of psychoactive substances.

Com a heterogeneidade de tecnologias de comunicação sem fio presentes na borda de redes de acesso, serviços providos na Internet podem ser acessados de forma quasi ubíqua através de dispositivos móveis ou portáteis. O acesso a esses serviços, contudo, está associado a atrasos e rupturas frequentes na comunicação devido a razões inerentes à mobilidade do dispositivo, como: i) perda de sinal em locais onde há pouca ou nenhuma cobertura de acesso móvel; ii) erros no quadro de dados durante a transmissão e, consequentemente, perdas de pacotes, que podem ser ocasionados por interferência no sinal ou enfraquecimento deste pelo distanciamento do dispositivo em relação à Estação Base; iii) mudanças de endereços IP durante transmissões em andamento causadas pela migração do dispositivo entre diferentes redes. Como consequência, aplicações falham com a ruptura de comunicações orientadas a conexão. Tratar a mobilidade de forma transparente à aplicação é um dos desafios da Computação Móvel e Ubíqua que vem sendo pesquisado ao longo da última década. Soluções foram propostas para operarem desde a Camada de Enlace à Aplicação. Muitas delas, entretanto, exigem modificações na pilha de protocolos TCP/IP e adição de infraestrutura específica de rede no suporte à comunicação fim-a-fim. Além de elevar o custo das etapas de implantação e manutenção, estratégias intrusivas e dependentes de infraestrutura adicional podem não apresentar desempenho satisfatório. Nesse contexto, propomos tratar a mobilidade no nível da própria aplicação através de Sessões de Comunicação que não falham com atrasos e desconexões. Operando somente nos nós-fim e de modo transparente às Camadas adjacentes de Aplicação e Transporte, as sessões não requerem infraestrutura adicional para intermediar ou controlar a comunicação entre pares, tampouco modificações em protocolos legados da pilha TCP/IP. O conceito de Sessões Tolerantes a Rupturas é implementado através de uma API de propósito geral em sistemas Linux que estende a interface de Sockets. A API é, na prática, uma camada transparente sobre o Socket que provê Ciência de Mobilidade à aplicação através de mecanismos para: acompanhar a localização de nós ao longo da duração de uma sessão; detectar rupturas nas transmissões causadas pela mobilidade do nó ou de seu par remoto; suspender e retomar sessões de forma eficiente, segura e confiável. Experimentos conduzidos em ambientes emulados e reais com equipamentos de uso comercial mostram a eficiência das sessões. Além de introduzir baixa degradação na vazão fim-a-fim, rupturas na transmissão podem ser detectadas em microssegundos e sessões suspensas são reabertas em milissegundos. Com um desempenho superior a solução de mobilidade geral da Camada IP, as sessões não necessitam de adaptações de software em equipamentos de rede / Nowadays services available on the Internet can be accessed from mobile devices while they roam across heterogeneous wireless networks. Due to the inherent reasons of device mobility, however, the access to such services is frequently involved with delay and disruptions. The most common reasons are: i) losing radio signal at places where mobile access coverage area is not available; ii) frame error, losses, and fading on the radio signal when the mobile device moves away from the Base Station; iii) changes on the devices IP address over ongoing transmission, while the mobile node migrates among different wireless networks. As result, networked application fails with disruptions on TCP connections established in the mobile users path. Handling seamlessly mobility on the Internet is a technical challenge of the Mobile Computing Paradigm. It has been widely researched over the last decade. Several solutions have been proposed to work from the Link Layer to the Application Layer. Most of them, however, work intrusively and require modifications in the classical TCP/IP protocol stack, as well as rely on additional network infrastructure to support mobile end-to-end communication. Besides increasing the cost of deployment and maintenance, intrusive and infrastructure dependent strategies may not present suitable performance. In this sense, we devised an architecture to handle mobility at the Application level by means of communication sessions that do not fail with delay, disruption or disconnection. Such sessions work only at the end-systems in a such way that: are fully transparent to the adjacent layers of Transport and Application; do not require additional network infrastructure to forward and manage the communication between two mobile peers; and do not impose any modification on the legacy protocols from the TCP/IP stack. The concept of Disruption-Tolerant Sessions is implemented in Linux by means of a general purpose API extended from the Socket interface. Such API is a transparent layer placed on top of the Socket to provide mobility awareness to the Application Layer. To do so, session services are provided for: tracking mobile peers along the session duration; detecting disruptions over TCP connection caused by mobility of the local or remote peer; suspending and resuming sessions with efficiency, security and reliability. Experiments conducted in emulated and real systems (off-the-shelf hardware and open source software) showed the desired efficiency. Besides introducing little overhead on the goodput, disruptions are detected in a range of microseconds and suspended sessions are resumed in milliseconds. With performance greater than the general IP layer mobility solution, the proposed sessions do not require software adaptation in the core of the network infrastructure

The world is changing, what has been known to work has been put to the test when both the geopolitical and the environmental climate are changing. War, a pandemic, material shortage, financial difficulties and an overall dis- tressed global transportation sector have shown that the ever-more important topic of resilience is crucial to stay relevant in today’s competitive markets. Companies are therefore switching focus towards ensuring sufficient supply chain resilience capabilities to handle these ever-changing situations on the global market.  In this thesis, we focus on how Volvo SML is working with resilience today, and how graph theory and optimisation can be useful tools when analysing a supply chain’s resilience. We made a qualitative analysis by conducting inter- views with employees and comparing our findings with capabilities related to resilience. In addition, we conducted a quantitative analysis by constructing a simulation of the supply chain, comparing two topology metrics and two op- timisation metrics, to analyse the robustness of the aftermarket supply chain.  We analysed the data and summarised the insights gathered from the inter- views using a resilience capability framework. Volvo SML proved to be agile and reactive when dealing with disruptions but is missing some key capabil- ities during the pre-and post-disruption phases. Some areas of improvement we identified were: robustness, collaboration and redundancy. We proved that the simulation is useful when evaluating the robustness of a supply chain, and we showed that a more flexible way of working would improve the overall robustness of Volvo SML’s aftermarket supply chain.

Supply chain disruptions, ranging from epidemics to geopolitical tensions, have been especially evident in recent years and have consequently become a hot topic in both boardrooms and academic literature. Supply chain resilience (SCR) denotes the ability to prepare, respond, recover, and facilitate growth during disruptions and is usually thought of as consisting of several enablers. Initial evidence suggests that one such enabler could be analytics, which broadly refers to the processing of data to support decision-making. This thesis aims to explore the use of analytics for SCR. The research design comprise one conceptual component followed by two empirical components consisting of a survey and interviews. The findings reveal six application areas for analytics in SCR. Three paths to SCR are also identified in terms of configurations of analytics and other SCR enablers, only one of which does not seem to be contingent on the level of supply chain complexity. Finally, obstacles to the use of analytics were identified. Clear consensus was noted for low data availability and/or quality as a major obstacle to SCR, while a somewhat consensus existed concerning the hindrance to quick decision-making, lack of a data-driven culture, and insufficient benefits and/or use. The thesis contributes to the nascent stream of research on the use of analytics and SCR by complementing individual observations with broader and deeper insights through the spectrum of application areas, configurations of analytics and complementary SCR-enablers, and finally, obstacles. For practitioners, the thesis provides insights into using analytics as a potential enabler for SCR. Firms can evaluate their current use of analytics for SCR and adjust their set of application areas and configurations of SCR-enablers as per the options outlined in the findings to better align with their specific needs and prerequisites. Finally, guidance is provided on what obstacles to be cognizant of and attempt to mitigate. / Störningar i försörjningskedjor, orsakade av händelser såsom pandemier och geopolitiska spänningar, har varit särskilt påtagliga under de senaste åren och har därmed blivit ett hett ämne både i näringslivet och akademin. Begreppet Supply chain resilience (SCR) avser försörjningskedjans förmåga att förbereda sig, reagera, återhämta sig och stödja tillväxt under sådana störningar. Det anses vanligtvis bestå av flera möjliggörare. Initiala bevis i litteraturen tyder också på att en av dessa möjliggörare kan vara analytics, som i stora drag betyder bearbetning av data för att stödja beslutsfattande. Denna avhandling syftar till att utforska användningen av analytics för SCR. Forskningsmetoden bestod av en konceptuell studie, följt av två empiriska studier i form av en enkät och intervjuer. Resultaten visar sex tillämpningsområden för analytics med avseende på SCR. Dessutom identifierades tre vägar till SCR när det gäller konfigurationer av analytics och andra SCR-möjliggörare, varav endast en konfiguration är oberoende av försörjningskedjans komplexitetsnivå. Slutligen identifierades hinder för användning av analytics för SCR. Det fanns en tydlig konsensus kring låg tillgänglighet och/eller kvalitet på data, medan det fanns viss enighet om hinder för snabba beslut, bristen på en kultur att basera beslutsfattande på analytics och slutligen otillräcklig nytta och/eller användning. Avhandlingen bidrar till forskning om användningen av analytics för SCR genom att komplettera enskilda observationer med bredare och djupare insikter om spektrumet av tillämpningsområden, konfigurationer av analytics och kompletterande SCR-möjliggörare, och slutligen, hinder. För praktiker ger avhandlingen insikter i att använda analytics som en potentiell möjliggörare för SCR. Företag kan utvärdera sin nuvarande användning av analytics för SCR och förändra tillämpningsområden och konfigurationer av SCR-möjligare enligt de identifierade alternativen för att bättre tillgodose sina behov och förutsättningar. Slutligen ges vägledning om vilka hinder man bör vara medveten om och försöka mildra.

Abstract  Date: 2023-05-30 Level: Master thesis in Business Administration, 15 cr  Institution: School of Business, Society and Engineering, Mälardalen University  Authors: Ramak Amyari Khamneh (84/01/29), Aymen Safi (00/03/27) Title: Artificial Intelligence as a Catalyst for Supply Chain Resilience: A Qualitative Study Comparing Scania and Volvo in the Construction Equipment Industry Supervisor: Emre Yildiz Keywords: Artificial Intelligence (AI), Supply Chain Resilience, Construction Equipment Industry, Disruptions, Agility, Redundancy Research question: How do Scania and Volvo interpret and implement Artificial Intelligence (AI) technologies to enhance supply chain resilience and mitigate disruptions in the construction equipment industry? Purpose: The purpose of this master thesis is to investigate how Scania and Volvo interpret and implement AI technologies to enhance supply chain resilience and mitigate disruptions in the construction equipment industry. Method: Qualitative Conclusion: The conclusion of the master thesis is that Scania and Volvo have successfully implemented AI technologies to enhance supply chain resilience in the construction equipment industry, despite challenges, and see AI as a critical component for future supply chain strategies.

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Cette thèse participe à accroitre les connaissances sur les facteurs régissant la structures des communautés benthiques de la Grande Vasière (GV) du Golfe de Gascogne. Une attention particulière a été portée au rôle du chalutage de fond, dont l’intensité a été estimée à l’aide des données VMS. A l’échelle de la GV, nos résultats suggèrent que le chalutage de fond serait le principal moteur de structuration du mégabenthos (> 10 mm). Cependant, cette hypothèse n’a pu être formellement démontrée en raison de la co-variation entre l’activité de pêche et certaines caractéristiques environnementales. Par conséquent, les travaux ont été poursuivis sur une zone restreinte de la GV, choisie de manière à minimiser les variations dans l’habitat, tout en conservant un large gradient d’intensité de chalutageNous avons ainsi observé des modifications saisonnières et temporaires de la structure des communautés méga et macro-benthiques (>1 mm) en lien avec le chalutage. Ils proviendraient essentiellement d’une disponibilité alimentaire accrue pour les prédateurs-charognards de la mégafaune et de modifications des caractéristiques sédimentaires pour la macrofaune. En revanche, l’étude de la diversité fonctionnelle montre que ces changements n’ont que des répercussions mineures sur le fonctionnement de l’écosystème. Nos conclusions suggèrent que l’écosystème benthique de la GV a probablement été façonné par plusieurs décennies de pêche intensive et qu’il est actuellement adapté à des perturbations anthropiques chroniques / This PhD thesis aims at increasing the knowledge on factors influencing the benthic community structures of the « Grande Vasière » (GV) of the Bay of Biscay. Particular attention has been paid to the role of bottom trawling whose intensity has been estimated using VMS data. At the scale of the GV, our results suggest that bottom-trawling is the main driver of the megabenthic community structure (> 10mm). However, this hypothesis has not been formally demonstrated due to the co-variations between the trawling intensity and certain environmental characteristics. Hence, works continued on a restricted part of the GV that displayed minimal variations of environmental characteristics while exhibiting a wide gradient of trawling intensityResults suggest that bottom-trawling induces seasonnal and transient modifications on the mega and macrobenthic (> 1mm) communities. These changes could be due to an increase of food availability for the megabenthic predator-scavengers and to changes of sedimentary characteristics for macrofauna. However, investigation about functional diversity showed that these changes did not have major consequences on ecosystem functioning. We concluded that decades of bottom trawling may have shaped the benthic ecosystem of the GV and that it is currently adapted to frequent disruptions.