Designing structures for lightness is an intelligent and responsible way for engineers and architects to conceive structural systems. Lightweight structures are able to bridge wide spans with a least amount of material. However, the quest for lightness remains an utopia without the driving constraints that give sense to contemporary structural design.<p><p>Previously proposed computational methods for designing lightweight structures focused either on finding an equilibrium shape, or are restricted to fairly small design applications. In this work, we aim to develop a general, robust, and easy-to-use method that can handle many design parameters efficiently. These considerations have led to truss layout optimization, whose goal is to find the best material distribution within a given design domain discretized by a grid of nodal points and connected by tentative bars. <p><p>This general approach is well established for topology optimization where structural component sizes and system connectivity are simultaneously optimized. The range of applications covers limit analysis and identification of failure mechanisms in soils and masonries. However, to fully realize the potential of truss layout optimization for the design of lightweight structures, the consideration of geometrical variables is necessary. <p><p>The resulting truss geometry and topology optimization problem raises several fundamental and computational challenges. Our strategy to address the problem combines mathematical programming and structural mechanics: the structural properties of the optimal solution are used for devising the novel formulation. To avoid singularities arising in optimal configurations, the present approach disaggregates the equilibrium equations and fully integrates their basic elements within the optimization formulation. The resulting tool incorporates elastic and plastic design, stress and displacements constraints, as well as self-weight and multiple loading.<p><p>Besides, the inherent slenderness of lightweight structures requires the study of stability issues. As a remedy, we develop a conceptually simple but efficient method to include local and nodal stability constraints in the formulation. Several numerical examples illustrate the impact of stability considerations on the optimal design.<p><p>Finally, the investigation on realistic design problems confirms the practical applicability of the proposed method. It is shown how we can generate a range of optimal designs by varying design settings. In that regard, the computational design method mostly requires the designer a good knowledge of structural design to provide the initial guess. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

The complexity associated with development of networked video games creates a need for tools for verifying a consistent player experience. Some networked games achieve consistency through the lockstep protocol, which requires identical execution of sent commands for players to stay synchronised. In this project a method for testing networked multiplayer lockstep games for synchronisation problems related to nondeterministic behaviour is formulated and evaluated. An integrated fuzzing AI is constructed which tries to cause desynchronisation in the tested game and generate data for analysis using log files. Scripts are used for performing semi-automated test runs and parsing the data. The results show that the test system has potential for finding synchronisation problems if the fuzzing AI is used in conjunction with the regular AI in the tested game, but not for finding the origins of said problems. / Komplexiteten förenad med utveckling av nätverksuppkopplade dataspel skapar ett behov av verktyg för att verifiera en konsistent spelarupplevelse. Vissa nätverksspel hålls konsistenta med hjälp av lockstep-protokollet, vilket kräver identisk exekvering av skickade kommandon för att spelarna ska hållas synkroniserade. I detta projekt formuleras och evalueras en metod för att testa om nätverksuppkopplade flerspelarspel lider av synkroniseringsproblem relaterade till ickedeterministiskt beteende. En integrerad fuzzing-AI konstrueras som försöka orsaka desynkronisering i det testade spelet och generera data för analys med hjälp av loggfiler. Skript används för att utföra halvautomatiserade testkörningar och tolka data. Resultaten visar att testsystemet har potential för att hitta synkroniseringsproblem om fuzzing-AI:n används tillsammans med den vanliga AI:n i det testade spelet, men inte för att hitta de bakomliggande orsakerna till dessa problem.

This licentiate thesis aims to understand how infection preventionists (IPs) continuously find problems and implement solutions related to health care-associated infections (HAIs) in hospital settings. HAIs are infections acquired by patients during the process of care and are among the main causes of deaths worldwide. Recently, practices for HAIs prevention and control have challenged IPs due to pandemics (e.g. COVID-19), antimicrobial resistance, population aging and limited resources in health care facilities. Such challenges demand actions to find, solve problems and implement solutions. However, IPs often fail to address these problems. The reasons stem from their inability to timely identify valuable problems and implement new solutions. Although the literature on infection prevention and control is well developed, previous studies have largely investigated how IPs implement preconceived practices to solve given problems as a single event, rather than on how to continuously find problems and implement solutions.  This licentiate thesis comprises two empirical papers. Paper I investigates how infection prevention and control teams find problems with HAIs, and is based on a multiple case study of three infection prevention and control teams from one Swedish and two Brazilian hospitals. Paper II investigates how IPs continuously implement changes in infection prevention and control practices during pandemics, and is based on a qualitative descriptive study. The data in both papers were collected from 44 semi-structured interviews with health care professionals enrolled as IPs in Brazilian and Swedish hospitals. The key theories and literatures covered include Problem-Finding and Problem-Solving Perspective and Implementation research. This licentiate thesis contains three main contributions. First, it advances the Problem-Finding and Problem-Solving Perspective literature by providing empirical evidence on how to create valuable knowledge from ill-structured and complex problems. Second, this licentiate thesis suggests a distinction between HAI prevention and HAI control based on two modes of decision-making for finding valuable problems with HAIs. Third, the licentiate thesis describes and categorizes sets of practices that allow to continuously implement changes of infection prevention and control practices during pandemics.

Dans cette thèse, nous nous intéressons à l'étude des structures déterminantielles apparaissent dans l'optimisation semi-définie (SDP), le prolongement naturel de la programmation linéaire au cône des matrices symétrique semi-définie positives. Si l'approximation d'une solution d'un programme semi-défini peut être calculé efficacement à l'aide des algorithmes de points intérieurs, ni des algorithmes exacts efficaces pour la SDP sont disponibles, ni une compréhension complète de sa complexité théorique a été atteinte. Afin de contribuer à cette question centrale en optimisation convexe, nous concevons un algorithme exact pour décider la faisabilité d'une inégalité matricielle linéaire (LMI) $A(x)\succeq 0$. Quand le spectraèdre associé (le lieu $\spec$ des $x \in \RR^n$ ou $A(x)\succeq 0$) n'est pas vide, la sortie de cet algorithme est une représentation algébrique d'un ensemble fini qui contient au moins un point $x \in \spec$: dans ce cas, le point $x$ minimise le rang de $A(x)$ sur $\spec$. La complexité est essentiellement quadratique en le degré de la représentation en sortie, qui coïncide, expérimentalement, avec le degré algébrique de l'optimisation semi-définie. C'est un garantie d'optimalité de cette approche dans le contexte des algorithmes exacts pour les LMI et la SDP. Remarquablement, l'algorithme ne suppose pas la présence d'un point intérieur dans $\spec$, et il profite de l'existence de solutions de rang faible de l'LMI $A(x)\succeq 0$. Afin d'atteindre cet objectif principal, nous développons une approche systématique pour les variétés déterminantielles associées aux matrices linéaires. Nous prouvons que décider la faisabilité d'une LMI $A(x)\succeq 0$ se réduit à calculer des points témoins dans les variétés déterminantielles définies sur $A(x)$. Nous résolvons ce problème en concevant un algorithme exact pour calculer au moins un point dans chaque composante connexe réelle du lieu des chutes de rang de $A(x)$. Cet algorithme prend aussi avantage des structures supplémentaires, et sa complexité améliore l'état de l'art en géométrie algébrique réelle. Enfin, les algorithmes développés dans cette thèse sont implantés dans une nouvelle bibliothèque Maple appelé Spectra, et les résultats des expériences mettant en évidence la meilleure complexité sont fournis. / In this thesis we focus on the study of determinantal structures arising in semidefinite programming (SDP), the natural extension of linear programming to the cone of symetric positive semidefinite matrices. While the approximation of a solution of a semidefinite program can be computed efficiently by interior-point algorithms, neither efficient exact algorithms for SDP are available, nor a complete understanding of its theoretical complexity has been achieved. In order to contribute to this central question in convex optimization, we design an exact algorithm for deciding the feasibility of a linear matrix inequality (LMI) $A(x) \succeq 0$. When the spectrahedron $\spec = \{x \in \RR^n \mymid A(x) \succeq 0\}$ is not empty, the output of this algorithm is an algebraic representation of a finite set meeting $\spec$ in at least one point $x^*$: in this case, the point $x^*$ minimizes the rank of the pencil on the spectrahedron. The complexity is essentially quadratic in the degree of the output representation, which meets, experimentally, the algebraic degree of semidefinite programs associated to $A(x)$. This is a guarantee of optimality of this approach in the context of exact algorithms for LMI and SDP. Remarkably, the algorithm does not assume the presence of an interior point in the spectrahedron, and it takes advantage of the existence of low rank solutions of the LMI. In order to reach this main goal, we develop a systematic approach to determinantal varieties associated to linear matrices. Indeed, we prove that deciding the feasibility of a LMI can be performed by computing a sample set of real solutions of determinantal polynomial systems. We solve this problem by designing an exact algorithm for computing at least one point in each real connected component of the locus of rank defects of a pencil $A(x)$. This algorithm admits as input generic linear matrices but takes also advantage of additional structures, and its complexity improves the state of the art in computational real algebraic geometry. Finally, the algorithms developed in this thesis are implemented in a new Maple library called {Spectra}, and results of experiments highlighting the complexity gain are provided.

This thesis deals with the retribution judicature within Czech cinematography in the years 1945-1948. Right after the Second World War, revolutionary denazification commission came into being on the level of companies and union boards. Almost 270 workers from all areas of cinematography underwent the process of the Disciplinary Board of the Union of Czech film workers, including cinema usherettes or directors of film companies. The cases were not judged on any legal basis, but rather under the supervision of a new cinematography leadership. For many of the workers it ended in being forced to leave the industry. Some of the cases were included into the proceedings of the Great Retribution Decree or the Small Retribution Decree. According to the Extraordinary People's Courts and the Penalty Finding Commissions the people were likely to end up in prison or with a fine, or for the worst case there was a possibility of the death sentence. Eventhough an extensive number of cinematography workers stood in front of these courts the conclusions had not such a big influence on the future of Czech film industry as it was in the case of the Disciplinary Board. Despite of this fact, the revolutionary and the offical branches of retribution are often mixed up. The aim of this thesis is to make a distinction and...

The diploma project is focused on finding a new urban solution for the Brno Exhibition Center. Based on the theoretical assumptions, it develops an urban strategy for the transformation of the western part of the BVV area. The central theme is the relocation of administrative functions and accompanying exhibition functions from the eastern part to the western part of the fairground. The main spatial concept of the study focuses primarily on the location of a new fire station.

The theme of this doctoral thesis is the design of concrete shell structures with the focus on finding their optimal shape. The optimal shape of a concrete shell is the shape in which for a given load (usually the dead weight of the structure) no significant bending moments are generated in the shell and the structure is in the so-called membrane state. The inspiration for this thesis is the work of Swiss engineer Heinz Isler, who developed the shapes of shell structures using model tests of appropriately loaded flexible membranes. He developed the shell structure for large spans by inverting the resultant shape, which carried its weight almost entirely via membrane forces. The numerical solution of the above experiments using Midas Civil is presented herein. The basic principles of the method are demonstrated on the example of sagged cable. The numerically found shapes are compared with the analytical solution. A shell is designed based on the numerically found shapes and its stress response to dead load is described, particularly in relation to the membrane action. In the next part, the acquired knowledge and methods were used to design three relatively complicated shell structures. Each structure was statically analysed and its static behaviour was described. Structures with perfectly rigid or flexible supports, which simulate real behaviour of the supports, were studied. In the final phase, the results of static analysis of the selected shell were experimentally verified on a physical model in a scale of 1: 55.56. The model has been built using 3D printing. The thesis describes the use of a modelling similarity, the model design, the production process, and the experiment. The load test confirmed the optimal design of the shell structure and the validity of the numerical method for finding their shapes.

[pt] Considerando a disponibilidade do Big Data para engenharia de software, como no caso do GitHub, a semi-automação da elicitação de requisitos não funcionais (NFRs) é uma estratégia fundamental para a definição de requisitos. Como tal, a elicitação de NFRs, dentro da automação da leitura de documentos, pode gerenciar a massa de informações valiosas existentes nos dados disponíveis. Esta tese explora esse contexto em três partes, a escolha de fontes apropriadas de informação, uma elicitação de descoberta de fatos e a identificação de NFRs. As avaliações realizadas mostraram que a automação enfrenta um balance entre eficiência e eficácia. Esse equilíbrio é detalhado com diferentes estratégias inovadoras. O conhecimento adquirido é organizado como um catálogo SIG (Softgoal Interdependence Graph). / [en] Considering the availability of Big Data for software engineering, as the case of GitHub, the semi-automation of non-functional requirements (NFRs) elicitation is a key strategy towards requirements definition. As such, NFRs elicitation, within the automation of document reading, can manage the mass of valuable information existing in available data. This thesis explores this context in three parts, the choice of proper sources of information, a fact-finding elicitation, and NFRs identification. The assessments performed showed that the automation faces a trade-off between efficiency and efficacy. This trade-off is detailed with different novel strategies. The acquired knowledge is organized as a SIG (Softgoal Interdependence Graph) catalog.

Learning Management Systems have become increasingly used in all levels of education since more people have access to computers and the internet. An important feature of the LMS is to provide students with information about their courses. This information, however, is not always easy to find. Especially when the system does not follow usability guidelines about how to provide your users with information. In this study four different course pages on the KTH LMS Canvas have been evaluated with a moderated usability test to asses how well users find information on the LMS. The results show that some improvements could be made by adhering more to usability guidelines and that the courses that did were easier for testers to navigate. Some conclusions that can be made are that users find things easier when there is a high similarity between link names and the information they are looking for and that users scan web pages rather than read them. This is in line with previous research. The conclusions lead to four recommendations to KTH that can improve the usability of all Canvas course pages. / Utbildningsplattformar används allt mer sen intågen av datorer och internet i människors hem. En viktig funktion på en utbildningsplattform är att ge studenter information om sina kurser. Dock är denna information inte alltid så lätt att hitta. Särskilt inte om plattformen inte följer de riktlinjer som finns för hur man förser användare med information på ett användarvänligt sätt. I denna studie har fyra olika KTH- Canvassidor undersökts med ett modererat användartest för att utvärdera hur lätt användare hittar information på utbildningsplattformen. Resultaten visar att vissa förbättringar kan ske genom att tydligare följa riktlinjerna för användarvänlighet och att kurserna som följde riktlinjerna bättre var lättare att navigera. Slutsater som kan dras är bland annat att det är lättare för användare att hitta information när länknamnet är likt den information som söks och att användare skumläser hemsidor istället för att läsa dem noggrant. Detta överensstämmer med resultat från tidigare studier. Från slutsatserna gjordes fyra rekommendationer till KTH som kan förbättra användarvänligheten för alla Canvassidor.

The aim of this thesis is to explore and discover how an immigrant ‘finds home’ inSweden through homeownership and to document first-hand experiences on their journey tohomeownership. Thirteen questions were sent via e-mail to twelve (12) participants whowere self-identified immigrants within Sweden. This deductive research rests on thetheoretical framework of the Theory of Finding Home (ToFH) and research on the meaningof ‘home’ that supports the hypothesis that homeownership contributes to an immigrant‘finding home’ in Sweden. The twelve (12) immigrants in Sweden of various backgroundsprovide the foundation for the analysis by elaborating on the relationship between owning ahome and the feeling of being at ‘home’ in Sweden. Home is found to be closely associatedwith feelings of belonging, comfort, safety, and financial well-being. The respondents’answers strongly suggest that owning a house/apartment in Sweden is a tremendousaccomplishment for an immigrant and serves as a major factor in finding the feeling of being‘at home.’