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This thesis contains a brief description of the apparatus, the procedure, and the results of an investigation of the absorption of cosmic rays in thin absorbers. The existence of an anomalous maximum at a thickness of 10.5 cm. of lead is reported, which is tenatively interpreted as being caused by the production of a penetrating ionizing radiation by a neutral radiation through some seemingly unknown process. / Thesis / Master of Science (MS)

The importance of school buildings, among the built heritage of a community, is largely acknowledged. Due to past seismic events, damage or even collapse of schools have had a huge social impact. The safety of children and youth has a fundamental priority and, in addition, the unsafety of schools can aggravate social dispersion phenomena which follow an earthquake. In the aftermath of the Molise earthquake (2002), which caused the collapse of a primary school in San Giuliano di Puglia (Campobasso, Italy) and the consequent death of 27 children and a teacher, the Italian government issued a national plan for the seismic vulnerability assessment of relevant and strategic structures all over the country. The huge number of structures to be evaluated makes this operation extremely complex and, after almost twenty years, it still requires efficient and cost-effective (also in terms of execution time) tools to be effectively planned. More recently, the United Nations adopted, in March 2015, the Sendai Framework for Disaster Risk Reduction 2015-2030, which is articulated in “priorities”, providing actions to be implemented. Specifically, Priority 1 is focused on “understanding disaster risk”, while Priority 2 sets the goal of “strengthening disaster risk governance to manage disaster risk”. Both objectives require to deepen knowledge of risks and of its components (i.e., hazard, exposure and vulnerability) at various territorial scale (e.g., national or urban). This thesis presents the seismic vulnerability and fragility assessment of school buildings in Italy, to address this problem at multiple scales, at municipality level and at national level, also including investigations on case studies for refined modelling. First, a prioritisation procedure to sort school buildings part of an urban stock by their seismic vulnerability is proposed. This procedure has the aim of supporting local administrations and enterprises in charge with built stocks in decision-making for the allocation of limited funds for retrofit. The knowledge process of the building stock is comprised of on-site visual surveys and retrieval of original projects documentations. Then, the priority list is defined based on the combination of a qualitative evaluation and of a quantitative capacity/demand ratio resulting from a simplified mechanics-based model. The former results from the application of a form, counting structural and non-structural deficiencies, which is proposed in this work for masonry, reinforced concrete (r.c.), and mixed masonry-r.c. buildings, by updating an existing form. The priority-ranking procedure was applied to r.c. school buildings managed by the Municipality of Padova, in north-east Italy. Then, in the second part of the thesis, the research focuses on the fragility assessment of macro-classes of buildings, representative of the Italian school taxonomy, aimed at risk evaluation at national scale. Based on the Italian school building census, macro-classes of buildings were identified according to a limited number of parameters (i.e., the construction material, age of construction, number of stories, and plan area). Fragility curves were derived for five damage states (from slight damage to complete collapse), with reference to the European Macroseismic Scale (EMS98). For masonry schools, fragility curves were derived for 265 building types by means of a simplified mechanics-based approach, named Vulnus, which accounts for both in-plane and out-of-plane responses. Fragility assessment was also carried out for a macro-class of r.c. school buildings by selecting two representative schools from the above-mentioned urban stock managed by the Municipality of Padova. A non-linear fibre model was developed for each prototype building, taking into account its specific features, such as the presence of infills and of non-seismic joints. Non-Linear Time History Analyses (NLTHA) were carried out by applying a great number of natural and scaled ground motion records, covering a large range of seismic intensities. Fragility curves were derived by statistically processing the outcomes of NLTHA. Thus, the application of two alternative approaches for fragility estimate are provided in this work. Finally, damage maps at national scale are provided by implementing the obtained fragilities, showing the distribution of expected damage for a selected return period and for observation time windows.

This research study presents two control solutions, PID and the novel hyper-clothoid control strategy, to autonomously navigate a car. These waypoint navigation solutions smoothly connect the given waypoints with C1 continuity using Hermite cubic splines which is used as a reference path for the controller to track. The PID controller uses lateral and heading error to generate a steering profile for the vehicle to track the constructed reference path. A novel real time solution is presented as the second control strategy which involves constructing clothoids to generate a steering profile. The resultant car trajectory preserves curvature and curvature rate continuity. A simulation test bench was developed in MATLAB and Simulink. Six benchmark waypoint datasets have been used for regression testing and validating the algorithms. Both the proposed control strategies have been implemented on a 2017 GM Chevy Bolt EV. A real time operating system (QNX) has been used and was time-synced with the localization suite in the test vehicle. Closed loop results with accuracies up to 50 cm of lateral error have been achieved using the test vehicle. / Doctor of Philosophy / The research into self-driving cars has been one of the most sought out areas these past couple of decades. There are many components into building a self-driving car - Sensing, Perception, Localization, Navigation. Lot of strategies have been developed over the years with waypoint navigation being the most widely used for navigation an autonomous vehicle. Waypoint Navigation utilizes GPS data to move the car from one point to the other. The traditional process of this strategy involves two parts - curve fitting between waypoints and using a control scheme to track the path with the car. Numerous methods have been developed to fit a curve in between two points. Most of these methods use a variant of 3rd degree or higher order polynomials . Also different control strategies have been developed to track the generated path. Model predictive control strategies are among the popular control architectures used for this purpose. This work proposes a novel method to track a path using clothoids. The proposed algorithm has a novel approach of integrating the path construction and control strategy. The algorithm also has a low computational requirement making it highly suitable for implementation in real-time.

Horizontal curves are a contributing factor for numerous deaths on roadways. The curve characteristics dictate the severity of the curve and require the driver to be more attentive while driving. To address this issue, advisory speeds are posted on horizontal curves to warn drivers to slow down for their safety. There are six main procedures to assign advisory speeds. This paper focuses on two of these methods, finds a connection between the two, and develops an Android Application that can be used to determine an advisory speed for a curve. In this work, a brief summary of the six existing methods for advisory speed assignment are discussed. Pros and cons are included for each for comparison purposes. Next, two of these methods are highlighted by applying them in the field. Data is collected and a relationship between them is determined. Using this relationship, an Android Application is created and the various details of the design process are described. This Application, called CurveAdvisor, allows the user to assign the appropriate advisory speed on a desired horizontal curve. An analysis is then conducted to test the effectiveness of CurveAdvisor. Results indicate that CurveAdvisor is successful in many cases. Finally, contributions and suggestions for future work are included. / Master of Science

This thesis deals with the relationship between form and strength in architecture. The proposed building is a Kindergarten which unites issues of shape, physics, and habitat. The roof is vaulted and the walls are curved for lateral resistance and in order to make folds scaled to a child. These physical moves work towards the theme of the Kindergarten: a place for the transition between home and school. / Master of Architecture

Estudos anteriores têm relatado um decremento na capacidade de produção de força com a idade. Mudanças estruturais e funcionais nos músculos esqueléticos tal como a sarcopenia (perda de massa muscular), diminuição da ativação das unidades motoras, co-contração aumentada da musculatura antagonista, diminuição da tensão da fibra muscular e rigidez do tendão são referidos para explicar a funcionalidade motora reduzida em indivíduos idosos. Este estudo objetivou investigar as mudanças ligadas à idade na produção de torque voluntário isométrico e isocinético (TVM), como também as respostas eletromiográficas (EMG). Hipotetizamos, como conseqüências do envelhecimento: a) uma redução da capacidade de produção de TVM; b) deslocamento da curva torque-ângulo (para a esquerda) na direção de menores comprimentos musculares; c) deslocamento da curva torque-velocidade (para a esquerda) na direção de menores velocidades; d) que uma menor ativação muscular seria observada. Quarenta indivíduos saudáveis, do gênero masculino, divididos igual e randomizadamente em quatro grupos (15-30; 31-45; 46-60 e 61-75 anos), participaram neste estudo como sujeitos, aos quais foram solicitados produzir torques máximos de extensão de joelho em um dinamômetro isocinético (Byodex®) em diferentes ângulos (15º; 30º;45º; 60º; 75º; 90º e 105º) e velocidades (60º/s; 120º/s; 180º/s; 240º/s; 300º/s e 360º/s) Sinais da EMG dos músculos da coxa, como vasto lateral, reto femoral e vasto medial foram simultaneamente registrados. O nível de atividade física foi avaliado pelo IPAQforma curta (International questionnaire of physical activity ). Valores de TVM, valores RMS do sinal EMG e nível de atividade física foram usados como medidas dependentes. Os resultados demonstraram uma diminuição no TVM com a idade. Particularmente, menores valores de TVM foram encontrados durante as maiores velocidades em condições isocinéticas. Nenhuma mudança foi observada nas curvas torque-ângulo e torque-velocidade e nenhuma mudança ligada à idade foram encontradas nas respostas da EMG. Concluímos que a idade afeta a produção de TVM, particularmente em maiores velocidades. Além disso, os resultados permitemnos apontar que os altos níveis de atividade física e demandas funcionais possam explicar a similaridade encontrada nas respostas EMG entre os diferentes grupos. / Previous studies have reported a decrease in force production ability with age. Structural and functional changes on the skeletal muscles such as sarcopenia (loss of muscle mass), decreased ability of motor unit firing, increased co-activation of antagonist muscle, decreased muscle fiber tension and tendon’s rigidity are taken into account for the reduced motor functionality in elderly individuals. This study aimed to investigate age-related changes of maximum voluntary isometric and isokinetic torque production (MVT), as well as electromyography (EMG) responses. We hypothesized that as consequence of aging: a) a reduced ability of MVT production; b) a torque/angle curve displacement (left side) towards the lowers muscle lengths; c) a torque/velocity curve displacement (left side) towards smaller velocities; d) and decreased muscle activation will be observed. Forty healthy male individuals, evenly and randomly divided in four age groups (15–30; 31– 35; 45– 60; 60–75 years old), participated in this study as subjects. The subjects were asked to produce maximum knee extension torques on the isokinetic dynamometer (Cybex ®) in different angles (15º; 30º; 45º; 60º; 75º; 90º and 105º) and velocities (60º/s; 120º/s; 180º/s; 240º/s; 300º/s and 360º/s) EMG signals from the upper leg muscles such as, vatsus lateralis, rectus femoris, vastus medialis, were simultaneously recorded. The level of physical activity was evaluated by the QIAF–short form (International questionnaire of physical activity). MVT values, RMS values from EMG signals and level of physical activity were used as dependent measures. The results showed a decrease in MVT with age. Particularly, lower values of MVT were found during higher velocities under isokinetic condition. No changes were observed for torque/angle and torque/velocity curves and no age-related changes were found on the EMG responses. We conclude that aging affects MVT production, particularly during high velocities. In addition, the results allowed us to point out that higher levels of physical activity and functional demand, showed by the older groups, could explain the similarities found on EMG responses among the different age groups.

O problema de seleção de características, no contexto de Reconhecimento de Padrões, consiste na escolha de um subconjunto X de um conjunto S de características, de tal forma que X seja \"ótimo\" dentro de algum critério. Supondo a escolha de uma função custo c apropriada, o problema de seleção de características é reduzido a um problema de busca que utiliza c para avaliar os subconjuntos de S e assim detectar um subconjunto de características ótimo. Todavia, o problema de seleção de características é NP-difícil. Na literatura existem diversos algoritmos e heurísticas propostos para abordar este problema; porém, quase nenhuma dessas técnicas explora o fato que existem funções custo cujos valores são estimados a partir de uma amostra e que descrevem uma \"curva em U\" nas cadeias do reticulado Booleano (P(S),<=), um fenômeno bem conhecido em Reconhecimento de Padrões: conforme aumenta-se o número de características consideradas, há uma queda no custo do subconjunto avaliado, até o ponto em que a limitação no número de amostras faz com que seguir adicionando características passe a aumentar o custo, devido ao aumento no erro de estimação. Em 2010, Ris e colegas propuseram um novo algoritmo para resolver esse caso particular do problema de seleção de características, que aproveita o fato de que o espaço de busca pode ser organizado como um reticulado Booleano, assim como a estrutura de curvas em U das cadeias do reticulado, para encontrar um subconjunto ótimo. Neste trabalho estudamos a estrutura do problema de minimização de funções custo cujas cadeias são decomponíveis em curvas em U (problema U-curve), provando que o mesmo é NP-difícil. Mostramos que o algoritmo de Ris e colegas possui um erro que o torna de fato sub-ótimo, e propusemos uma versão corrigida e melhorada do mesmo, o algoritmo U-Curve-Search (UCS). Apresentamos também duas variações do algoritmo UCS que controlam o espaço de busca de forma mais sistemática. Introduzimos dois novos algoritmos branch-and-bound para abordar o problema, chamados U-Curve-Branch-and-Bound (UBB) e Poset-Forest-Search (PFS). Para todos os algoritmos apresentados nesta tese, fornecemos análise de complexidade de tempo e, para alguns deles, também prova de corretude. Implementamos todos os algoritmos apresentados utilizando o arcabouço featsel, também desenvolvido neste trabalho; realizamos experimentos ótimos e sub-ótimos com instâncias de dados reais e simulados e analisamos os resultados obtidos. Por fim, propusemos um relaxamento do problema U-curve que modela alguns tipos de projeto de classificadores; também provamos que os algoritmos UCS, UBB e PFS resolvem esta versão generalizada do problema. / The feature selection problem, in the context of Pattern Recognition, consists in the choice of a subset X of a set S of features, such that X is \"optimal\" under some criterion. If we assume the choice of a proper cost function c, then the feature selection problem is reduced to a search problem, which uses c to evaluate the subsets of S, therefore finding an optimal feature subset. However, the feature selection problem is NP-hard. Although there are a myriad of algorithms and heuristics to tackle this problem in the literature, almost none of those techniques explores the fact that there are cost functions whose values are estimated from a sample and describe a \"U-shaped curve\" in the chains of the Boolean lattice o (P(S),<=), a well-known phenomenon in Pattern Recognition: for a fixed number of samples, the increase in the number of considered features may have two consequences: if the available sample is enough to a good estimation, then it should occur a reduction of the estimation error, otherwise, the lack of data induces an increase of the estimation error. In 2010, Ris et al. proposed a new algorithm to solve this particular case of the feature selection problem: their algorithm takes into account the fact that the search space may be organized as a Boolean lattice, as well as that the chains of this lattice describe a U-shaped curve, to find an optimal feature subset. In this work, we studied the structure of the minimization problem of cost functions whose chains are decomposable in U-shaped curves (the U-curve problem), and proved that this problem is actually NP-hard. We showed that the algorithm introduced by Ris et al. has an error that leads to suboptimal solutions, and proposed a corrected and improved version, the U-Curve-Search (UCS) algorithm. Moreover, to manage the search space in a more systematic way, we also presented two modifications of the UCS algorithm. We introduced two new branch-and-bound algorithms to tackle the U-curve problem, namely U-Curve-Branch-and-Bound (UBB) and Poset-Forest-Search (PFS). For each algorithm presented in this thesis, we provided time complexity analysis and, for some of them, also proof of correctness. We implemented each algorithm through the featsel framework, which was also developed in this work; we performed optimal and suboptimal experiments with instances from real and simulated data, and analyzed the results. Finally, we proposed a generalization of the U-curve problem that models some kinds of classifier design; we proved the correctness of the UCS, UBB, and PFS algorithms for this generalized version of the U-curve problem.