No description available.

No description available.

No description available.

No description available.

Free vibrations of a thin elastic circular cylindrical panel localized near the rectilinear edge, propagating along the edge and decaying in its circumferential direction, are investigated in the framework of the two-dimensional equations in the Kircho↵-Love theory of shells. At first the panel is assumed to be infinite longitudinally and semi-infinite along its length of curvature (of course not realistically possible), followed by the assumption that the panel is then finite along its length of curvature and fixed and free conditions are imposed on the second resulting boundary. Using the comprehensive asymptotic analysis detailed in Kaplunov et al. (1998) “Dynamics of Thin Walled Elastic Bodies”, leading order asymptotic solutions are derived for three types of localized vibration, they are bending, extensional, and super-low frequency. Explicit representation of the exact solutions cannot be obtained due to the degree of complexity of the solving equations and relevant boundary conditions, however, computational methods are used to find exact numerical solutions and graphs. Parameters, particularly panel thickness, wavelength, poisson’s ratio, and circumferential panel length, are varied, and their e↵ects on vibration analyzed. This analysis is further extended to investigate localized vibration on the interface (perfect bond) of two cylindrical panels joined at their respective rectilinear edges, propagating along the interface and decaying in the circumferential direction away from the interface. An earlier, similar, localized vibration problem presented in Kaplunov et al. (1999) “Free Localized Vibrations of a Semi-Infinite Cylindrical Shell” and Kaplunov and Wilde (2002) “Free Interfacial Vibrations in Cylindrical Shells” is replicated for comparison with all cases. The asymptotics are similar, however in this problem the numerics highlight the stronger e↵ect of curvature on the decay of the super-low frequency vibrations, and to some extent on the leading order bending vibration.

Sports interventions programmes for children have gained popularity in recent years as a response to a number of welfare issues, including rising levels of obesity, declining fitness, academic attainment and delinquent behaviour. Faith in sport to address these different issues indicates that it is seen as an expedient ‘cure all’ solution. However, despite calls for evidence, few studies have addressed the impact of a programme on children’s health, fitness and well-being. This study investigates the impact of a sport intervention programme called “Move It” on (n = 785) participants (11-14 years of age) attending 3 secondary schools in inner city London between 2004 and 2007. Various measures were undertaken to monitor health, fitness, and self-evaluated self-esteem, academic attainment and behaviour. In addition, Case Study was used to understand more about a programme’s implementation at a particular school and to uncover any features that were not apparent in the earlier analysis. Results indicated that, over three years, there was no conclusive evidence of positive outcomes to health, fitness, and self-evaluated self-esteem, academic attainment and behaviour. Moreover the level of engagement of a school was not found to have an impact on quantitative outcomes. However, Case Study evidence indicated that a programme can be managed toward outcomes specifically targeted by the school, such as creating personal development avenues, opportunities for pupils, and improving social cohesion. Findings are discussed with respect to theoretical and policy developments and recommendations for future research are offered.

A análise de agrupamento de dados é uma tarefa fundamental em mineração de dados e aprendizagem de máquina. Ela tem por objetivo encontrar um conjunto finito de categorias que evidencie as relações entre os objetos (registros, instâncias, observações, exemplos) de um conjunto de dados de interesse. Os algoritmos de agrupamento podem ser divididos em particionais e hierárquicos. Uma das vantagens dos algoritmos hierárquicos é conseguir representar agrupamentos em diferentes níveis de granularidade e ainda serem capazes de produzir partições planas como aquelas produzidas pelos algoritmos particionais, mas para isso é necessário que seja realizado um corte (por exemplo horizontal) sobre o dendrograma ou hierarquia dos grupos. A escolha de como realizar esse corte é um problema clássico que vem sendo investigado há décadas. Mais recentemente, este problema tem ganho especial importância no contexto de algoritmos hierárquicos baseados em densidade, pois somente estratégias mais sofisticadas de corte, em particular cortes não-horizontais denominados cortes locais (ao invés de globais) conseguem selecionar grupos de densidades diferentes para compor a solução final. Entre as principais vantagens dos algoritmos baseados em densidade está sua robustez à interferência de dados anômalos, que são detectados e deixados de fora da partição final, rotulados como ruído, além da capacidade de detectar clusters de formas arbitrárias. O objetivo deste trabalho foi adaptar uma variante da medida da Modularidade, utilizada amplamente na área de detecção de comunidades em redes complexas, para que esta possa ser aplicada ao problema de corte local de hierarquias de agrupamento. Os resultados obtidos mostraram que essa adaptação da modularidade pode ser uma alternativa competitiva para a medida de estabilidade utilizada originalmente pelo algoritmo estado-da-arte em agrupamento de dados baseado em densidade, HDBSCAN*. / Cluster Analysis is a fundamental task in Data Mining and Machine Learning. It aims to find a finite set of categories that evidences the relationships between the objects (records, instances, observations, examples) of a data set of interest. Clustering algorithms can be divided into partitional and hierarchical. One of the advantages of hierarchical algorithms is to be able to represent clusters at different levels of granularity while being able to produce flat partitions like those produced by partitional algorithms. To achieve this, it is necessary to perform a cut (for example horizontal) through the dendrogram or cluster tree. How to perform this cut is a classic problem that has been investigated for decades. More recently, this problem has gained special importance in the context of density-based hierarchical algorithms, since only more sophisticated cutting strategies, in particular nonhorizontal cuts (instead of global ones) are able to select clusters with different densities to compose the final solution. Among the main advantages of density-based algorithms is their robustness to noise and their capability to detect clusters of arbitrary shape. The objective of this work was to adapt a variant of the Q Modularity measure, widely used in the realm of community detection in complex networks, so that it can be applied to the problem of local cuts through cluster hierarchies. The results show that the proposed measure can be a competitive alternative to the stability measure, originally used by the state-of-the-art density-based clustering algorithm HDBSCAN*.

The objective of this thesis is to obtain knowledge regarding how effective user centred evaluation methods are and how user centred evaluations are conducted by IT professionals. This will be achieved by exploring user centred evaluation in experimental and practical settings. The knowledge gained in these studies should inspire suggestions for further research and suggestions for improvements on the user centred evaluation activity. Two experimental studies were conducted. One compares the results from using three user centred evaluation methods, and the other examines two factors while conducting heuristic evaluation. The results show that the think-aloud evaluation method was the most effective method in finding realistic usability problems of the three methods. The number of critical problems found during think-aloud evaluation increases, if heuristic evaluation is conducted prior to the think-aloud evaluations. Further, two studies of user centred evaluation in practical settings were performed. The IT professionals participating in those studies were using the software development process Scrum to plan their work. The results show that user centred evaluation is infrequently conducted in Scrum projects, compared to testing activities like acceptance testing. The main type of evaluation is qualitative. Few participants measure user performance or use surveys to gather quantitative results on the usability and the user experience. IT professionals get feedback from users in an informal way and gather informal feedback from peers. Many participants use a mixture of methods for gathering feedback on their work. The outcome of this thesis shows that IT professionals should be encouraged to include users whenever possible when evaluating software, for example by using the think-aloud method. Using heuristic evaluation prior to conducting think-aloud evaluations is also recommended. In addition, IT professionals are encouraged to evaluate their software in an informal way frequently, rather than waiting for the right time to conduct a thorough quantitative evaluation. To advance this field further, researchers who want to improve the evaluation activity for the IT professionals should study how user centred evaluation methods could be combined in an efficient way and how the use of qualitative evaluation methods could be made more effective. / QC 20120522

Information is a central theme of the twenty-first century. This is evident in the fact that everyday objects are being augmented to provide information. Thus, ubiquitous computing – providing information using everyday objects – becomes increasingly popular. The problem is that information requires attention for acquisition. Hence, ubiq- uitous computing puts a strain on attention, which is limited. There are many innovations that attempt to solve this problem; this thesis focusses on one: calm technology, which was introduced to interface design by Mark Weiser. Calm tech- nology attempts to reduce the attention required to acquire information. Ideally, calm technology would provide information without requiring any attention. I call this technology unattended. Calm technology research, however, typically provides little evidence showing that calm artifacts reduce the amount of attention required. Moreover, evaluations that are conducted on individual artifacts often fail to generalize. That is, evalua- tions only apply to the artifact that is evaluated. They do not identify properties of the artifact that make it calm. In this thesis, I design and conduct a dual task experiment. The results of the experiment indicate that users can perform an attention saturating primary task, and acquire information from a calm artifact not involved in the task, without sacrificing performance on the primary task. Thus, the artifact does not require any attention, as can be measured by the experiment, while providing information. Thus, the artifact is unattended, which provides an existence proof for unattended technology.

Information is a central theme of the twenty-first century. This is evident in the fact that everyday objects are being augmented to provide information. Thus, ubiquitous computing – providing information using everyday objects – becomes increasingly popular. The problem is that information requires attention for acquisition. Hence, ubiq- uitous computing puts a strain on attention, which is limited. There are many innovations that attempt to solve this problem; this thesis focusses on one: calm technology, which was introduced to interface design by Mark Weiser. Calm tech- nology attempts to reduce the attention required to acquire information. Ideally, calm technology would provide information without requiring any attention. I call this technology unattended. Calm technology research, however, typically provides little evidence showing that calm artifacts reduce the amount of attention required. Moreover, evaluations that are conducted on individual artifacts often fail to generalize. That is, evalua- tions only apply to the artifact that is evaluated. They do not identify properties of the artifact that make it calm. In this thesis, I design and conduct a dual task experiment. The results of the experiment indicate that users can perform an attention saturating primary task, and acquire information from a calm artifact not involved in the task, without sacrificing performance on the primary task. Thus, the artifact does not require any attention, as can be measured by the experiment, while providing information. Thus, the artifact is unattended, which provides an existence proof for unattended technology.