Desktop and mobile computing devices increasingly store critical data, both personal and professional in nature. Yet, the enormous code bases of their monolithic operating systems (hundreds of thousands to millions of lines of code) are likely to contain exploitable weaknesses that jeopardize the security of this data in the file system. Using a highly componentized system architecture based on a microkernel (or a very small hypervisor) can significantly improve security. The individual operating system components have smaller code bases running in isolated address spaces so as to provide better fault containment. Their isolation also allows for smaller trusted computing bases (TCBs) of applications that comprise only a subset of all components. In my thesis, I built VPFS, a virtual private file system that is designed for such a componentized system architecture. It aims at reducing the amount of code and complexity that a file system implementation adds to the TCB of an application. The basic idea behind VPFS is similar to that of a VPN, which securely reuses an untrusted network: The core component of VPFS implements all functionality and cryptographic algorithms that an application needs to rely upon for confidentiality and integrity of file system contents. These security-critical cores reuse a much more complex and therefore untrusted file system stack for non-critical functionality and access to the storage device. Additional trusted components ensure recoverability.

Alongside the evolution of the recruitment process, different types of recommendation systems have been developed. The purpose of this study is to investigate recommendation systems within educational contexts, successful implementations of recommendation system architecture patterns, and alternatives to previous experience when evaluating candidates. The study is conducted through two separate methods; A literature review with a qualitative approach and design science research methodology focused on design and development, demonstration and evaluation. The literature review shows that, for recommendation systems, a layered architecture built within a microservice ecosystem is successfully utilized and has multiple beneficial aspects such as improved scalability, maintainability and security. Through design science research methodology, this study shows a suggested approach to implementing a layered architecture in combination with KNN and hybrid filtering. To avoid the lapse of suitable candidates, caused by demanding previous experience, this study shows an alternative approach to recruitment, within an educational context, through the use of soft skills. Within the study, this approach is successfully used to evaluate and compare students, but the same approach could possibly be applied to evaluate and compare companies. Moving forward, this study could be further expanded by looking into possible biases arising as a result of using AI and choices made during this study, as well as weighting of student-attributes.

The diploma thesis Principles of information visualization in public transit information systems considers the ways information design affects one of the most common activities of people in an urban environment: the use of public transit system. In this work, the city space becomes a framework for several disciplines connected to the concept of wayfinding. The author sets the topic in a wide historical and architectural context and links the connections with cognitive science. The case study describes principals for information design using the example of the Prague subway and their application to an experimental station with a new information system installed.

<p>  Modern datacenter network applications continue to demand ultra low latencies and very high throughputs. At the same time, network infrastructure keeps achieving higher speeds and larger bandwidths. We still need better network management solutions to keep these two demand and supply fronts go hand-in-hand. There are key metrics that define network performance such as flow completion time (the lower the better), throughput (the higher the better), and end-to-end latency (the lower the better) that are mainly governed by how effectively network application get their fair share of network resources. We observe that buffer utilization on network switches gives a very accurate indication of network performance. Therefore, network buffer management is important in modern datacenter networks, and other network management solutions can be efficiently built around buffer utilization. This dissertation presents three solutions based on buffer use on network switches.</p> <p>  This dissertation consists of three main sections. The first section is on a specification language for buffer management in modern programmable switches. The second section is on a congestion control solution for Remote Direct Memory Access (RDMA) networks. The third section is on a solution to head-of-the-line blocking in modern datacenter networks.</p>

The microservice architecture is widely considered to be best practice. Yet, there still exist many companies currently working in monolith systems. This can largely be attributed to the difficult process of updating a systems architecture. The first step in this process is to identify microservices within a monolith. Here, artificial intelligence could be a useful tool for automating the process of microservice identification. The aim of this thesis was to propose a deep learning-based model for the task of microservice identification, and to compare this model to previously proposed approaches. With the goal of helping companies in their endeavour to move towards a microservice-based architecture. In particular, the thesis has evaluated whether the more complex nature of newer deep learning-based techniques can be utilized in order to identify better microservices. The model proposed by this thesis is based on overlapping community detection, where each identified community is considered a microservice candidate. The model was evaluated by looking at cohesion, modularity, and size. Results indicate that the proposed deep learning-based model performs similarly to other state-of-the-art approaches for the task of microservice identification. The results suggest that deep learning indeed helps in finding nontrivial relations within communities, which overall increases the quality of identified microservices, From this it can be concluded that deep learning is a promising technique for the task of microservice identification, and that further research is warranted. / Allmänt anses mikrotjänstarkitekturen vara bästa praxis. Trots det finns det många företag som fortfarande arbetar i monolitiska system. Detta då det finns många svårigheter runt processesen av att byta systemaritekture. Första steget i denna process är att identifiera mikrotjänster inom en monolit. Här kan artificiell intelligens vara ett användbart verktyg för att automatisera processen runt att identifiera mikrotjänster. Denna avhandling syftar till att föreslå en djupinlärningsbaserad modell för att identifiera mikrotjänster och att jämföra denna modell med tidigare föreslagna modeller. Målet är att hjälpa företag att övergå till en mikrotjänstbaserad arkitektur. Avhandlingen kommer att utvärdera nyare djupinlärningsbaserade tekniker för att se ifall deras mer komplexa struktur kan användas för att identifiera bättre mikrotjänster. Modellen som föreslås är baserad på överlappande klusterdetektion, där varje identifierad kluster betraktas som en mikrotjänstkandidat. Modellen utvärderades genom att titta på sammanhållning, modularitet och storlek. Resultaten indikerar att den föreslagna djupinlärningsbaserade modellen identifierar mikrotjänster av liknande kvalitet som andra state-of-the-art-metoder. Resultaten tyder på att djupinlärning bidrar till att hitta icke triviala relationer inom kluster, vilket ökar kvaliteten av de identifierade mikrotjänsterna. På grund av detta dras slutsatsen att djupinlärning är en lovande teknik för identifiering av mikrotjänster och att ytterligare forskning bör utföras.

Microservices is one of the most commonly used buzzword of the systems architecture industry and is being adopted by several of the world’s largest technology companies such as Netflix, Uber and Amazon. The architecture which embraces splitting up your system in smaller independent units is an extension of the service-oriented architecture and an opponent of the monolithic architecture. Being a top buzzword and promises of extreme scalability has spiked the interest for microservices, but unlike the relatively simple monolithic architecture the complexity of microservices creates a new set of obstacles. This work sheds a light on these issues and implements solutions for some of the most frequent problems using a case study. The study shows that while microservices can help reduce the inner complexity of a system, it greatly increases the outer complexity and creates the need for a variety of tools aimed at distributed systems. It also concludes that communication and data storage are two of the most frequently occurring issues when developing microservices with the most difficult one being how you reason with and structure your data, especially for efficient queries across microservices. / Microservices eller så kallade mikrotjänster är ett ofta förekommande buzzword inom systemarkitektur och nyttjas av flera teknikjättar som exempelvis Netflix, Uber och Amazon. Arkitekturen som bygger på att dela upp sina system i mindre oberoende delar är en utbyggnad av den tjänstorienterade arkitekturen och numera motståndare till den klassiska monolitiska arkitekturen. En plats högt upp på trendlistan och lovord om extrem skalbarhet har gjort att intresset för mikrotjänster är enormt, men till skillnad från den relativt simpla monolitiska arkitekturen skapar komplexiteten hos mikrostjänster en rad nya hinder. Det här arbetet belyser dessa hinder och implementerar även lösningar för de vanligaste förekommande problemen med hjälp av en fallstudie. Resultatet visar att även fast en mikrotjänstarkitektur kan minska systemets interna komplexitet så leder det till en markant ökning av systemets yttre komplexitet och det skapas ytterligare behov av en mängd olika verktyg och tjänster designade för distribuerade system. Studien visar också att de två mest förekommande problemen vid utveckling av en mikrotjänstarkitektur är kommunikation och datalagring där hantering och struktur av data är den mest komplicerade och kräver mycket kunskap, speciellt för att skapa effektiva datasökningar som sträcker sig över flera mikrotjänster.

A 3D bioprinter employing light-based technology has been designed and constructed in an EU-funded research initiative known as BRIGHTER (Bioprinting by Light-Sheet Lithography). This initiative is a collaborative effort between institutions and companies and aims to develop a technique for efficient and accurate production of engineered tissue. Presently, the bioprinter’s function is limited to 2D printing, with the lack of 3D printing capabilities.  The problem addressed is the integration of two separate electronic systems within the bioprinter to control the laser beam’s trajectory for 3D printing. The goal of the project is to create functional software and simulation tools to control the hardware modules in a precise and synchronized manner, thereby enabling 3D printing. The outcome manifests as a software prototype, which successfully facilitates intercommunication between the two electronic subsystems within the bioprinter, thereby enabling further progress on the bioprinter with 3D printing available. Nevertheless, the prototype requires thorough testing to determine its optimal operational efficiency in terms of timing the movements for the various hardware modules. / En 3D-bioprinter som använder ljusbaserad teknik har designats och konstruerats i ett EU-finansierat forskningsinitiativ som kallas BRIGHTER (Bioprinting by Light-Sheet Lithography). Detta initiativ är ett samarbete mellan institutioner och företag och syftar till att utveckla en teknik för effektiv och korrekt produktion av konstruerad vävnad.  I dagsläget har bioprintern inte möjligheten för 3D-utskrift, utan är begränsad till 2D-utskrift. Problemet som åtgärdas är integrationen av två separata elektroniska system inom bioprintern för att styra laserstrålens bana för 3D-utskrift. Målet med projektet är att skapa funktionell mjukvara och simuleringsverktyg för att styra hårdvarumodulerna på ett exakt och synkroniserat sätt och därigenom möjliggöra 3D-utskrift. Resultatet av examensarbetet är en mjukvaruprototyp, som framgångsrikt möjliggör interkommunikation mellan de två elektroniska systemen inom bioprintern och därigenom öppnar möjligheten för vidare arbete med 3D-utskrift tillgängligt. Prototypen kräver dock noggranna tester för att fastställa dess optimala operativa effektivitet när det gäller koordinationen av hårdvarumodulernas rörelser.

This work focuses on the need for new knowledge to allow hierarchical multi-project management to be conducted in the construction industry, which is characterised by high uncertainty, fragmentation, complex decisions, dynamic changes and long-distance communication. A dynamic integrated project management approach is required at strategic, tactical and operational levels in order to achieve adaptability. The work sees the multi-project planning and control problem in the context of supply chain management at main contractor companies. A portfolio manager must select and prioritise the projects, bid and negotiate with a wide range of clients, while project managers are dealing with subcontractors, suppliers, etc whose relationships and collaborations are critical to the optimisation of schedules in which time, cost and safety (etc) criteria must be achieved. Literature review and case studies were used to investigate existing approaches to hierarchical multi-project management, to identify the relationships and interactions between the parties concerned, and to investigate the possibilities for integration. A system framework was developed using a multi-agent-system architecture and utilising procedures adapted from literature to deal with short, medium and long-term planning. The framework is based on in-depth case study and integrates time-cost trade-off for project optimisation with multi-attribute utility theory to facilitate project scheduling, subcontractor selection and bid negotiation at the single project level. In addition, at the enterprise level, key performance indicator rule models are devised to align enterprise supply chain configuration (strategic decision) with bid selection and bid preparation/negotiation (tactical decision) and project supply chain selection (operational decision). Across the hierarchical framework the required quantitative and qualitative methods are integrated for project scheduling, risk assessment and subcontractor evaluation. Thus, experience sharing and knowledge management facilitate project planning across the scattered construction sites. The mathematical aspects were verified using real data from in-depth case study and a test case. The correctness, usefulness and applicability of the framework for users was assessed by creating a prototype Multi Agent System-Decision Support System (MAS-DSS) which was evaluated empirically with four case studies in national, international, large and small companies. The positive feedback from these cases indicates strong acceptance of the framework by experienced practitioners. It provides an original contribution to the literature on planning and supply chain management by integrating a practical solution for the dynamic and uncertain complex multi-project environment of the construction industry.

Made available in DSpace on 2016-04-29T14:23:45Z (GMT). No. of bitstreams: 1 Wander de Moraes Paes.pdf: 1162817 bytes, checksum: 45da7f91468b50a422ea7d8a7cd4f2a1 (MD5) Previous issue date: 2008-08-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The concept of sharing computing resources among WEB participants, has been gradually extended to support scenarios in wireless world, networks, mobile devices which introduce a variety possible uses. Wireless devices become a key of sharing information among peoples. In this point of view we present the main challenges in pervasive/ubiquitous concepts for wireless applications networks, focusing on the resource of systems and information interoperability. The idea about interdisciplinary culture, as instrument of dissemination and production of the knowledge in the digital environment, is a factor that also is applied to the environment of the mobile devices that remain the necessity of a study related to the interoperability what refers to the communication and the exchange information among peoples. This phenomenon shows up as a trend of the systems solutions in Wireless environments and WEB due to variety use of the electronic devices without wire as: cellular, PDA´s, Smartphone and Pocket PC. The consolidation of the Internet as a collaboration environment as well as the sprout of the mobile applications had directly influenced the business solutions and the systems architecture in the contemporary society. This new cartographic map of the decentralized services in cyberspace is fertile environment for the study about mobile medias environment and its consequence among stakeholders in ciberspace, a scene that represents significant impact in the contribution of the information in the development of the interfaces of the mobile systems. This map of information characterizes for a harmonic acquaintance between the centralization and the decentralization of the information in the mobile network. Therefore, the specific objective of the thesis involves the idea about mobile interoperability devices under the phenomenal about: mobility, cyberspace, portable devices and the technological aspects of the hybrid networks and new media architecture. The emergency of this context represents an important research study of the technology due a great solution offered by telecom corporations and political government. The aim of this research does not only approach the technological aspect centered in design of systems and programs, but also it focuses the benefits of the interoperability about all the flow of the information, deriving of the decentralized flow of information in wireless environment and WEB, these aspects had influenced the companies and the society in the digital culture. These solutions prevail are inside the same solution for the collaboration and people integration in cyberspace / O conceito da cultura interdisciplinar, como instrumento de disseminação e produção do conhecimento no ambiente digital é um fator que também se aplica ao ambiente dos dispositivos móveis. O que traduz a necessidade de um estudo relacionado à interoperabilidade das informações no que tange a comunicação e a troca das informações por meio destes últimos. O tecnologia sem fio afirma-se como tendência das soluções sistêmicas devido à popularização do uso dos dispositivos eletrônicos (celular, PDA´s, Smartphone e Pocket PC) e principalmente pelo papel da sociedade como parte integrante no dinamismo do processo de colaboração das informações. A consolidação da Internet e do surgimento da tecnologia móvel, sob a perspectiva da colaboração das informações, influenciou diretamente as soluções de negócio e os sistemas computacionais na sociedade contemporânea. Esse novo mapa cartográfico dos serviços descentralizados no ciberespaço é um palco fértil para o estudo da influência das mídias móveis e seu reflexo nas relações humanas. O que representou um impacto significativo no ambiente de desenvolvimento de sistemas inserido num ambiente heterogêneo que se caracteriza também por uma convivência harmônica entre a centralização e a descentralização das informações. Portanto, o objetivo específico dessa dissertação é apresentar a idéia da interoperabilidade dos dispositivos móveis sob o contexto dos fenômenos contemporâneos da mobilidade, ciberespaço móvel e os aspectos tecnológicos das redes e arquitetura de sistemas móveis. A emergência deste contexto representa um palco fértil para o estudo da tecnologia sem fio oferecida pelas grandes corporações. O foco desta pesquisa não aborda somente os aspectos tecnológicos centrados no design de sistemas e programas, mas também enfoca a interoperabilidade em todo o fluxo das informações na WEB e no emergente ambiente tecnológico Wireless com abordagens que influenciaram as empresas e a sociedade na cultura digital. O que representa o meio digital móvel e a interoperabilidade como parte integrante de uma mesma inovação tecnológica como solução para a colaboração das informações e integração de pessoas no ciberespaço

Les tempêtes hivernales causent des pertes en bois qui s’élèvent à 50% du volume des dégâts dans les forêts européennes. Les phénomènes de déracinement des arbres (chablis) sont les plus fréquents or ils sont encore mal compris. Cette thèse vise à mieux comprendre le processus de déracinement de l’arbre et à identifier les traits structuraux et matériels (racines, sol) ayant un effet du premier ordre sur l’ancrage racinaire dans le cas du Pinus pinaster. Un modèle d’éléments finis a été développé et permis de simuler et suivre la chronologie des ruptures successives au cours du déracinement. Un seuil de rupture globale de l’ancrage est ainsi défini comme une résultante de l’architecture et de la résistance des matériaux en jeu (racines, sol). Cela devrait permettre à terme d’améliorer les modèles de risque au vent qui actuellement n’incluent pas de relation mécaniste pour le chablis. Dans la même logique, nous nous sommes appuyés sur les données expérimentales pour construire une architecture simplifiée du système racinaire du P. pinaster. L’importance des différentes composantes sur le mécanisme d’ancrage a été étudiée et le rôle essentiel joué par le pivot et les racines traçantes montré. Ce résultat confirme de nombreuses études expérimentales et théoriques et pour la première fois permet de quantifier ces effets. Le nombre de paramètres pertinents pourra ainsi être réduit pour exprimer l’ancrage. Cela ouvre des perspectives intéressantes pour simplifier l’utilisation du modèle pour l’appliquer à d’autres espèces, d’autres conditions de sol et différentes pratiques sylvicoles. / Winter storms cause 50% of wood damage by volume to European forests. Tree uprooting isthe most frequent phenomenon during storms ; however the mechanism is not well understood.This thesis aims to better understand the tree uprooting process and to identify both rootstructural features and material properties which have first-order effects on tree anchoragestrength for the case ofPinus pinaster. A Finite Element Model has been developed and allowedsimulating and tracking the sequential root breakage during the course of tree overturning. Anoverall tree anchorage strength is thus defined as the resultant of contribution of root systemarchitecture and material strength (roots, soil). This would allow improving the risk modelswhich currently don’t include any mechanistic relationships to describe tree uprooting. In thesame spirit, we have relied on root architectural data to build a simplified root system patternwith features ofP. pinaster. Importance of different root components has been studied andthe essential role of the taproot and shallow roots demonstrated. This result has confirmednumerous experimental and theoretical studies and for the first time quantified these impacts.Therefore the number of relevant parameters can be reduced to express overall root anchorage.This opens new prospects to simplify the model in order to apply to other species under othersoil conditions and considering different silvicultural practices