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Um die Anwendung der Methode der experimentellen Tragsicherheitsbewertung auch für Bauteile zu ermöglichen, die eine Gefährdung eines gering duktilen Versagens, wie des Biegeschubversagens, aufweisen, wurden diese Versagensform und ihre messtechnisch erfassbare Vorankündigung ausführlich analysiert. Bisher waren solche sprödbruch-gefährdeten Bauteile von einer experimentellen Untersuchung ausgeschlossen, weil keine geeigneten Kriterien zur sicheren Bestimmung der Versuchsgrenzlast existierten. Diese Wissenslücke wurde in dieser Arbeit geschlossen und Indikatoren bzw. Kriterien entwickelt, die eine sichere Bestimmung der maximal zulässigen Beanspruchung während eines Belastungsversuches an einem schubbeanspruchten und sprödbruchgefährdeten Bauteil ermöglichen. In der Arbeit wurde ein zweigeteilter Ansatz verfolgt, bei dem zunächst durch theoretische Überlegungen die Gefahr eines spröden Schubversagens beurteilt werden kann. Dazu wurden die geschichtliche Entwicklung der Schubbemessung analysiert und eine Bewertung sowie ein Vergleich der verschiedenen Bemessungsregeln durchgeführt. Damit und aus der Analyse der maßgeblichen Einflussfaktoren auf das Schubtragverhalten von Stahlbetonbauteilen, konnten Randbedingungen formuliert werden, für die ein Schubversagen bereits im Vorfeld einer experimentellen Untersuchung ausgeschlossen werden kann. Ist es trotzdem notwendig, die Schubtragsicherheit eines Stahlbetonbauteiles experimentell nachzuweisen, können die in dieser Arbeit formulierten Kriterien zur Beurteilung des Tragzustandes verwendet werden. Um die theoretisch entwickelten Indikatoren zu praxistauglichen Kriterien hocharbeiten zu können, wurden experimentelle Untersuchungen an Stahlbetonbalken ohne und mit geringer Schubbewehrung durchgeführt. Dabei zeigte sich, dass für die Beurteilung des Schubtragverhaltens vor allem die schräge Rissentstehung und entwicklung maßgeblich sind. Um den kritischen Rissbildungszustand beurteilen zu können, wurde zwischen lokaler und globaler Schubschädigung unterschieden. Für die messtechnische Wahrnehmung bzw. Erfassung der schrägen Rissentwicklung wurden herkömmliche Verformungsmesstechniken wie Induktive Wegaufnehmer und Dehnungs-messungsstreifen mit der Nahbereichsphotogrammetrie und der Schallemissionsanalyse kombiniert eingesetzt. In den Versuchen konnte der Übergang vom spröden Versagen infolge Querkraft hin zu duktilem Biegeversagen durch die Veränderung der Schubschlankheit und des Bügelbewehrungsgrades gezeigt werden. Bereits geringe Bügelbewehrungsmengen führten zu einem wesentlich duktileren Verformungsverhalten und einem Versagen, das eine deutliche Vorankündigung zeigt. Aus den durchgeführten theoretischen Überlegungen und experimentellen Untersuchungen wurden Empfehlungen für die Vorgehensweise bei experimentellen Tragsicherheitsbewertungen schubgefährdeter Konstruktionen abgeleitet. / In order to allow the application of loading tests (experimental evaluation of the load bearing safety) for structural members, that are deemed to fail brittle, e. g. in shear compression, this type of failure and its measurable announcement have been studied in detail. Up till today structural members endangered of brittle failures could not be investigated experimentally, because no appropriate criteria for the determination of the ultimate test load existed. This gap in knowledge was closed in this thesis and indicators and criteria were developed, which allow the detection of the maximum allowable load during load testing of shear critical structures with the risk of a brittle failure. In this work a two-step approach is chosen. At first theoretical considerations are presented with which the danger of a brittle shear failure can be evaluated. Therefor the historical development of the shear design was analyzed and an evaluation and comparison of the different shear design rules are given. Therewith and with the analysis of the significant influencing factors on the shear bearing behavior of reinforced concrete members, boundary conditions were proposed for which a shear failure can be excluded in advance of an experimental evaluation of the load bearing safety. However, if it is still necessary to experimentally evaluate the shear bearing safety of a reinforced concrete structural member, the criteria given in this thesis can be utilized for the evaluation of the bearing condition. To develop the theoretically derived indicators up to practical criteria experimental investigations on reinforced concrete beams without and with low shear reinforcement have been carried out. It was shown that the formation and development of inclined cracks are the most significant indicators for a developing shear failure. For the assessment of the critical crack condition a distinction between local and global shear damage was formulated. For the perception and detection of the inclined crack development common deformation measurements as inductive displacement transducers and strain gauges were combined with close-range photogrammetry and acoustic emission analysis. In the experimental investigations the transition from brittle shear failure to ductile bending failure was shown by varying the shear-to-depth-ratio and the amount of shear reinforcement. Already low amounts of shear reinforcement led to a significantly ductile deformation behavior and a failure with a clear advanced notice. With the theoretical considerations and the experimental investigations recommendations for experimental evaluations of the shear bearing safety were derived.

More and more companies use a REST architecture to implement applications for an easy to use API. One important quality attribute of an application is the performance. To be able to understand how the application will perform it is important to know how the selected framework perform. By testing the performance of different frameworks it will become easier for software developers to choose the right framework to achieve their requirements and goals. At the time when this paper was written the research in this area was limited. This paper answered the question of which framework between Express, .NET Core, Spring and Flask that had the best performance. To be able to know how frameworks performed the author needed to measure them. One way of measuring performance is with response time from the server. The author used a controlled experiment to collect raw data from which the results was drawn. The author found out that Spring had the best overall performance between the different categories. By analysing the results the author also found out that performance differed a lot between the frameworks in some categories.

The increasing worldwide demand for software systems involved in society has led to the need where not only functionality is fundamental and addressed, but end-user satisfaction in terms of availability, throughput, and response time is essential and should be preserved. Thus, systems must be evaluated at preset load levels to assess the non-functional quality problems from the closest perspective of real application use. In this context, where the problem involves a high and complex search space, a search-based approach for load test generation is required. This thesis proposes and evaluates an evolutionary search-based approach for load test generation using multi-objective optimization methods consisting of selection, crossover, and mutation operators. In this thesis, load testing is addressed as a multi-objective optimization problem by using four different evolutionary algorithms: Non-dominated Storing Genetic Algorithm II (NSGA-II), Pareto Archived Evolution Strategy (PAES), The Strength Pareto Evolutionary Algorithm 2 (SPEA2), Multi-Objective Cellular Genetic Algorithm (MOCell) as well as a Random Search algorithm. Additionally, this study demonstrates the applicability of the proposed approach by running several experiments, aiming to compare the algorithms’ efficiency based on different quality indicators such as hypervolume, spread, and epsilon. Experimental results show that evolutionary search-based methods can be used to generate effective workloads. Since, all algorithms have found the optimal workload, having the hypervolume values to zero, we believe that the objectives of the problem could be combined as a single objective, hence scalarization techniques can be applicable. Based on the other quality indicators (Spread and Epsilon respectively), NSGA-II and MOCell tend to perform better compared to other algorithms. Finally, the study concludes that multi-objective evolutionary algorithms can be used for load testing purpose, obtaining better results in generating optimal workloads than an existing (adapted) model-free reinforcement learning approach.

With the growth of cloud computing, various delivery models have emerged to attract developers looking for scalable and cost-effective infrastructures for their software. Traditionally, applications are developed as a monolith with one single codebase repository, and they are easily deployed; for example as Platform as a Service (PaaS). However, monolithic applications have received criticism for inefficient resource handling when deployed on the cloud; therefore, new delivery models have been introduced as alternatives. Recent research points towards Function as a Service (FaaS) to potentially solve the issue of inefficient resource handling and, therefore, reduce costs. Furthermore, since multiple distinct development strategies and delivery models exist, it becomes increasingly important to choose the right strategy from the beginning since migrating to another development strategy or deployment model in the future is rather expensive. This thesis load tests monolithic and serverless applications to determine which development approach best suits performance, scalability, and cost requirements. The findings obtained showed that an application implemented with a serverless architecture can be a better strategy if the application needs to be able to handle a sudden large up-scaling. Otherwise, both architectures showed similar results to stable workloads. Regarding costs, the serverless architecture optimized costs on a smaller scale but further analysis showed that it can surpass the costs of a monolithic architecture if it surpasses a threshold of requests per month. / Nya molntjänster har lanserats för att locka utvecklare som letar efter skalbara och kostnadseffektiva infrastrukturer för sin programvara. Traditionellt utvecklas applikationer som en monolit med en enda kodbas, och de är lätta att lansera; till exempel med Platform as a Service (PaaS). Monolitiska applikationer har dock fått kritik för ineffektiv resurshantering när de distribueras i molnet; därför har nya servicemodeller introducerats som alternativ. Ny forskning pekar mot Function as a Service (FaaS) för att potentiellt lösa problemet med ineffektiv resurshantering och därför minska kostnaderna. Dessutom, eftersom det finns flera olika utvecklingsstrategier och servicemodeller, blir det allt viktigare att välja rätt strategi från början eftersom att det kan bli dyrt att migrera till en annan strategi i framtiden. Detta examensarbete testar en monolitisk applikation och en serverlös applikation för att avgöra vilken utvecklingsmetod som passar bäst gällande prestanda, skalbarhet och kostnadskrav. Resultaten som erhölls visade att en applikation implementerad med en serverlös arkitektur kan vara en bättre strategi om applikationen ska kunna hantera en snabb uppskalning. Annars visade båda arkitekturerna liknande resultat när det var stabilare arbetsbelastningar. Serverlösa arkitekturen optimerade kostanderna i en mindre skala, men vidare analyser visade att kostnaden kan överskrida en monolitisk arkitektur om applikationens efterfrågan skulle passera ett visst antal användare per månad.

Objetivos: Avaliar a percepção da dispneia em pacientes com fibrose cística (FC) comparando com indivíduos normais, durante teste com cargas resistivas inspiratórias e durante teste de caminhada de seis minutos (TC6M). Secundariamente, avaliar a correlação entre os escores de dispneia induzida pelas cargas resistivas e os escores de dispneia provocada pelo TC6M. Métodos: estudo transversal em pacientes com FC (≥15 anos) e indivíduos normais. Os voluntários foram submetidos a teste com cargas resistivas inspiratórias, medida das pressões respiratórias máximas, espirometria, avaliação nutricional e TC6M. Resultados: Foram incluídos no estudo 31 pacientes com FC pareados com 31 indivíduos normais. À medida que a magnitude das cargas resistivas inspiratórias aumentou, os escores de dispneia aumentaram (p<0,001), porém não houve diferença entre grupos quanto ao escore de dispneia (p=0,654) e não houve efeito de interação (p=0,654). SpO2 foi menor em pacientes com FC (p<0,001) e aumentou à medida que a magnitude das cargas aumentou (p<0,001), sem ocorrer efeito de interação (p=,364). Vinte e seis (84%) indivíduos normais completaram o teste com cargas resistivas, comparado com apenas 12 (39%) dos pacientes com FC (p<0,001). Os escores de dispneia foram maiores ao final do TC6M do que no repouso (p<0,001), mas não houve diferença entre os grupos (p=0,080) e não houve efeito de interação (p=0,091). SpO2 foi menor nos pacientes com FC (p<0,001) e diminuiu do repouso ao final do TC6M nos pacientes com FC (p<0,001) com efeito de interação (p=0,004). Os escores de dispneia ao final do TC6M correlacionaram-se significativamente com os escores de dispneia induzidos pelo teste com cargas resistivas. Conclusão: a percepção da dispneia em pacientes com FC induzidos por teste com cargas resistivas inspiratórias e pelo TC6M não diferiu dos indivíduos normais. Contudo, os pacientes com FC descontinuaram o teste com cargas resistivas inspiratórias mais frequentemente. Além disso, houve correlação significativa entre o escore de percepção da dispneia induzida pelas cargas resistivas inspiratórias e pelo TC6M. / Objectives: To evaluate dyspnea perception in cystic fibrosis (CF) patients compared with normal subjects, during inspiratory resistive loading and the six-minute walk test (6MWT). Secondarily, to assess the correlation between dyspnea scores induced by resistive loads and those induced by the 6MWT. Methods: cross-sectional study in patients with CF (≥15 years old) and normal subjects. Volunteers underwent inspiratory resistive loading, measurement of maximal respiratory pressures, spirometry, nutritional evaluation, and the 6MWT. Results: Thirty-one CF patients and 31 paired normal subjects were included in the study. As the magnitude of the inspiratory loads increased, dyspnea scores increased (p<.001), but there was no difference between groups in dyspnea score (p=.654) and no group interaction effect (p=.654). SpO2 was lower in CF patients (p<.001) and increased as the magnitude of the loads increased (p<.001), with no interaction effect (p=.364). Twenty-six (84%) normal subjects completed the whole test, compared to only 12 (39%) CF patients (p<.001). Dyspnea scores were higher post-6MWT than at rest (p<.001), but did not differ between groups (p=.080) with no interaction effect (p=.091). SpO2 was lower in CF patients (p<.001) and decreased from resting to post-6MWT in CF patients (p<.001) with an interaction effect (p=.004). Post-6MWT dyspnea scores were significantly correlated with dyspnea scores induced by resistive loads. Conclusion: dyspnea perception in CF patients induced by inspiratory resistive loading and by 6MWT did not differ from normal subjects. However, CF patients discontinued inspiratory resistive loading more frequently. In addition, there were significant correlations between dyspnea perception score induced by inspiratory resistance loading and by the 6MWT.

Objetivos: Avaliar a percepção da dispneia em pacientes com fibrose cística (FC) comparando com indivíduos normais, durante teste com cargas resistivas inspiratórias e durante teste de caminhada de seis minutos (TC6M). Secundariamente, avaliar a correlação entre os escores de dispneia induzida pelas cargas resistivas e os escores de dispneia provocada pelo TC6M. Métodos: estudo transversal em pacientes com FC (≥15 anos) e indivíduos normais. Os voluntários foram submetidos a teste com cargas resistivas inspiratórias, medida das pressões respiratórias máximas, espirometria, avaliação nutricional e TC6M. Resultados: Foram incluídos no estudo 31 pacientes com FC pareados com 31 indivíduos normais. À medida que a magnitude das cargas resistivas inspiratórias aumentou, os escores de dispneia aumentaram (p<0,001), porém não houve diferença entre grupos quanto ao escore de dispneia (p=0,654) e não houve efeito de interação (p=0,654). SpO2 foi menor em pacientes com FC (p<0,001) e aumentou à medida que a magnitude das cargas aumentou (p<0,001), sem ocorrer efeito de interação (p=,364). Vinte e seis (84%) indivíduos normais completaram o teste com cargas resistivas, comparado com apenas 12 (39%) dos pacientes com FC (p<0,001). Os escores de dispneia foram maiores ao final do TC6M do que no repouso (p<0,001), mas não houve diferença entre os grupos (p=0,080) e não houve efeito de interação (p=0,091). SpO2 foi menor nos pacientes com FC (p<0,001) e diminuiu do repouso ao final do TC6M nos pacientes com FC (p<0,001) com efeito de interação (p=0,004). Os escores de dispneia ao final do TC6M correlacionaram-se significativamente com os escores de dispneia induzidos pelo teste com cargas resistivas. Conclusão: a percepção da dispneia em pacientes com FC induzidos por teste com cargas resistivas inspiratórias e pelo TC6M não diferiu dos indivíduos normais. Contudo, os pacientes com FC descontinuaram o teste com cargas resistivas inspiratórias mais frequentemente. Além disso, houve correlação significativa entre o escore de percepção da dispneia induzida pelas cargas resistivas inspiratórias e pelo TC6M. / Objectives: To evaluate dyspnea perception in cystic fibrosis (CF) patients compared with normal subjects, during inspiratory resistive loading and the six-minute walk test (6MWT). Secondarily, to assess the correlation between dyspnea scores induced by resistive loads and those induced by the 6MWT. Methods: cross-sectional study in patients with CF (≥15 years old) and normal subjects. Volunteers underwent inspiratory resistive loading, measurement of maximal respiratory pressures, spirometry, nutritional evaluation, and the 6MWT. Results: Thirty-one CF patients and 31 paired normal subjects were included in the study. As the magnitude of the inspiratory loads increased, dyspnea scores increased (p<.001), but there was no difference between groups in dyspnea score (p=.654) and no group interaction effect (p=.654). SpO2 was lower in CF patients (p<.001) and increased as the magnitude of the loads increased (p<.001), with no interaction effect (p=.364). Twenty-six (84%) normal subjects completed the whole test, compared to only 12 (39%) CF patients (p<.001). Dyspnea scores were higher post-6MWT than at rest (p<.001), but did not differ between groups (p=.080) with no interaction effect (p=.091). SpO2 was lower in CF patients (p<.001) and decreased from resting to post-6MWT in CF patients (p<.001) with an interaction effect (p=.004). Post-6MWT dyspnea scores were significantly correlated with dyspnea scores induced by resistive loads. Conclusion: dyspnea perception in CF patients induced by inspiratory resistive loading and by 6MWT did not differ from normal subjects. However, CF patients discontinued inspiratory resistive loading more frequently. In addition, there were significant correlations between dyspnea perception score induced by inspiratory resistance loading and by the 6MWT.

As the Internet has become increasingly important for people and for businesses that rely on it to create revenue, Internet unavailability can have major consequences. A common cause to unavailability is performance related problems. In order to evade such problems, the system’s quality characteristics in terms of performance need to be evaluated, which is commonly done with performance testing. When performance tests are conducted, the system under test is driven by an artificial workload or a sample of its natural workload while performance related metrics are measured. The workload is a very important aspect of performance testing, proved by measured performance metrics being directly dependent on the workload processed by the system under test. In order to conduct performance tests with representative workloads, the concept of workload modelling should be considered. Workload models attempt to model all relevant features of the workload experienced by a system within a given period of time. A workload model is created by set of consecutive activities that together constitute a process. This explorative feasibility study focuses on exploring, describing and evaluating the feasibility of a tool for automating the process of modelling Web server workloads for performance testing. A literature review was conducted in this student thesis, from which a research model was developed that describes the key factors in the process of modelling Web server workloads for performance testing, the relationships between these factors and their variables. The key factors constitute of four sub-processes and the relationships between them are the sequence flow, i.e. the order of events in the process. The process is initiated by the sub-process Establish Workload Data, where the workload data are retrieved and sanitised. The workload data are then categorised in homogeneous groups called workload entities, which is done in the Identify Workload Entities sub-process. Each workload entity has some associated workload attributes that are identified in the Identify Workload Attributes sub-process. In the last sub-process, Represent Workload, statistical methods, such as standard deviation and arithmetic mean, are applied in order to represent the workload in graphs and tables. Based on the research model and in order to evaluate the feasibility of a tool, a prototype was developed. The feasibility was evaluated through analysis of the primary empirical data, collected from an interview with a field expert who had tested the prototype. The analysis indicated that developing a tool for automating the process of modelling Web server workloads for performance testing is indeed feasible, although some aspects should be addressed if such a tool was to be realised. Analysis implied that an important aspect of modelling Web server workloads for performance testing is that the modeller must be in controller of what is being modelled. The prototype that was developed is highly static, i.e. it is not possible to create customised workload models. Therefore, if the tool is going to be realised, functionality for customising workload models should be added to the tool. Another important aspect that should be addressed if the tool is going to be realised is graphical representation of multiple workload attributes. The analysis indicated that there might be correlations between workload attributes. It is therefore important to be able to graphically represent multiple workload attributes together so that such correlations can be identified.