Orientadores: Sonia Maria Gomes, Philippe Remy B. Devloo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-12T16:13:07Z (GMT). No. of bitstreams: 1 Farias_AgnaldoMonteiro_M.pdf: 8740364 bytes, checksum: 603f864d40bd5cd37235d0c7e8f5000e (MD5) Previous issue date: 2008 / Resumo: Em muitas situações na modelagem de problemas aplicados, o que se deseja de uma solução da Equação Diferencial Parcial que descreve o modelo, não é a própria solução e sim alguma quantidade de interesse. De forma geral, estas quantidades de interesse são caracterizadas por funcionais lineares limitados no espaço de funções que contém as soluções. Como exemplo, tem-se: a derivada da solução, o fluxo através de uma região da fronteira, o valor médio da solução sobre uma região do domínio, o valor da solução em um ponto etc. Em tais circunstâncias, nem sempre o refinamento uniforme ou uma estratégia de hp-refinamento, que diz respeito à qualidade global da solução, são as estratégias mais apropriadas para melhorar a aproximação da quantidade, pois podem tornar o custo computacional muito alto. Neste sentido, estratégias direcionadas para o aprimoramento da aproximação de quantidades de interesse são temas que têm recebido grande interesse nas últimas décadas. Um dos objetivos deste trabalho é o estudo de métodos para o pós-processamento da solução por elementos finitos com objetivo de se obter uma precisão desejável na aproximação das quantidades de interesse. Em particular, estudam-se dois métodos: a estratégia de adaptatividade goal-oriented e o método da função de extração. / Abstract: In many situations in the modeling of applied problems, what is wish is not the solution of governing partial differential equation system but rather a quantities of interest. In general, the quantities of interest are characterized by bounded linear functionals on the space of functions to which the solutions belongs. As an example, we have: the derivative of the solution, the flux through part of the bondary of the domain, the average of the solution over a subdomain, the value of the solution in a point etc. In this circumstances, the uniform refinement or a strategy for hp-refinement, which concerns the overall quality of the solution, not always are the most appropriate strategies to improve the approximation of the quantity, because the computational cost may become too high. In this sense, strategies directed to improve the accuracy of quantities of interest are topics that have received considerable interest in recent decades. One of the objectives of this work is the study of post-processing methods of the solution by finite elements in order to achieve a desirable precision in the approximation of quantities of interest. In particular two methods are studied: the strategy goal-oriented adaptivity and the method of the extraction function. / Mestrado / Analise Numerica / Mestre em Matemática Aplicada

Community colleges serve a diverse population of learners including many older students counting on the community college for enhanced skills or personal enrichment. Many of these colleges target this population with programs designed specifically to meet the needs and goals of the older adult but may not consider this population when designing a website. Older users of a community college website have similar needs to the traditional student; however, little was known about the impact of the typical navigational links on the successful completion of tasks and obtaining information for this type of user. It is essential for educational institution website designers to understand which navigational links will provide the best usability for older adults with differing levels of experience. Previous research has found that usage-oriented links and pages that offer both usage and subject-oriented links yield statistically higher performance than subject-oriented links. Other research has found that presenting navigational links in the form of an action enhances usability. For this study, three websites were created utilizing navigational links in the form of usage-oriented links, subject-oriented navigational links, and then a combination of both to conduct a usability study to expand on previous work. This study was designed to determine the impact of such navigation on obtaining the correct answer, time on task, and the user's perception of the navigation. The research question, Does website usability and the user's perception of usability vary for older users based on navigational links, task type, and audience type? was addressed through two hypotheses and data which were obtained during the study. The first hypothesis: Website navigation, task type, and audience type significantly affect usability, was based on performance, and was measured on the two components, correct answer ratio (CAR) and navigation time (NT). The results indicated that the older user's ability to complete tasks faster and more accurately depended on the user's experience level, the difficulty of the task, and the types of navigational links presented, with usage-based navigation being the more effective solution. The second hypothesis: Website navigation, task type, and audience type significantly affect perceptions of usability, was based on perception questions presented after task completion and was measured by a four question post-test questionnaire, which used a 7-point Likert scale. This study found the older user's perception of usability varied based on the navigational links presented, but the experience level of the participant or the task type did not have a significant effect on the perception of usability. Therefore, it is recommended that designers of educational sites present navigational links in a goal-oriented, action-based format to support the end users of all ages and to enhance usability of the institution's website. This research found that if developers emphasize accuracy and the need to navigate quickly as a goal of an educational website for the older user, the website should be designed using a usage-based navigation structure. This research provides the detail to support a better understanding of which navigation type results in higher usability for the older user and enhances the guidelines of website design for this population.

Intelligent robots are rational agents. The rationality of robots working cooperatively is significantly different from robots working independently. Cooperation between intelligent robots requires the high level of reasoning and complex interactions for successful operations. The required reasoning process includes knowledge representation and sharing as well as the ability to understand the context of a situation. The reasoning process heavily influences on the planning of deciding what actions need to be taken. Goal deliberation and planning is the process that deals with those requirements. This dissertation investigates the problem of goal deliberation and planning to enable such cooperation between goal-oriented intelligent robots, working as a team. The dissertation then proposes a multi-robot system model that embraces results of the investigation. The proposed model is realized on the top of the platform ‘robot operating system’ (ROS). The implemented system, named ‘goal-oriented multi agent systems’ (GOMAS), is demonstrated with the computer game, StarCraft II. Units in StarCraft II are individually controlled by the GOMAS robots and work cooperatively to attain a set of goals given from operators. The demonstration with the three different scenarios validates that the GOMAS system successfully and efficiently deliberates and plans the given goals.

Business processes are essential instruments used for the coordination of organisational activities in order to produce value in the form of products and services. Information security is an important non-functional characteristic of business processes due to the involvement of sensitive data exchanged between their participants. Therefore, potential security shortfalls can severely impact organisational reputation, customer trust and cause compliance issues. Nevertheless, despite its importance, security is often considered as a technical concern and treated as an afterthought during the design of information systems and the business processes which they support. The consideration of security during the early design stages of information systems is highly beneficial. Goal-oriented security requirements engineering approaches can contribute to the early elicitation of system requirements at a high level of abstraction and capture the organisational context and rationale behind design choices. Aligning such requirements with process activities at the operational level augments the traceability between system models of different abstraction levels and leads to more robust and context-aware operationalisations of security. Therefore, there needs to be a well-defined and verifiable interconnection between a system’s security requirements and its business process models. This work introduces a framework for the design of secure business process models. It uses security-oriented goal models as its starting point to capture a socio-technical view of the system to-be and its security requirements during its early design stages. Concept mappings and model transformation rules are also introduced as a structured way of extracting business process skeletons from such goal models, in order to facilitate the alignment between the two different levels of abstraction. The extracted business process skeletons, are refined to complete business process models through the use of a set of security patterns, which standardise proven solutions to recurring security problems. Finally, the framework also offers security verification capabilities of the produced process models through the introduction of security-related attributes and model checking algorithms. Evaluation of this work is performed: (i) through individual evaluation of its components via their application in real-life systems, (ii) a workshop-based modelling exercise where participants used and evaluated parts of the framework and (iii) a case study from the public administration domain where the overall framework was applied in cooperation with stakeholders of the studied system. The evaluation indicated that the developed framework provides a structured approach which supports stakeholders in designing and evaluating secure business process models.

The education sector can be seen as a cornerstone of today's society, an organization that is under constant change and evolve as society. The compulsory school system is of significant role in society that places high demands on its management. The following study investigates the requirements for documentation in primary school organization and operations, and how these requirements are perceived and affect the school's organization and activities of the study carried out at different levels of the organization so as to get an overall picture of its impact.   In order to analyze and create understanding of the results, the study applies the theory of New Public Management and various reforms that can be linked to the increased documentation requirements and its influence in the public administration. Study results show that there is a mixed picture of the documentation impact on the school system. Shown are both positive and negative effects of the documentation requirements. It also becomes clear that there is a connection between the theory and the increased documentation requirements.

This thesis aims to develop a knowledge structuring framework to organize knowledge according to means-ends relationships. Means-ends relationships are particularly relevant in technology and goal-oriented domains such as the geo-engineering domain, where technical problems are identified, and solutions proposed. The proposed goal oriented representation in this thesis does not replace current classification methodologies. In this project, a small corpus of research publications from a technology domain is used to help construct the framework. The main means-ends relationships from the articles are manually extracted and represented in a graphical model showing which problems are approached, by which solutions proposed, and in which publications. Proposed solutions can lead to new problems which are in turn addressed by solutions proposed in other publications. A metamodel is derived to capture the important concepts and relationships relevant for this purpose. The metamodel, and the framework have undergone several iterations before finalization.

This thesis aims to develop a knowledge structuring framework to organize knowledge according to means-ends relationships. Means-ends relationships are particularly relevant in technology and goal-oriented domains such as the geo-engineering domain, where technical problems are identified, and solutions proposed. The proposed goal oriented representation in this thesis does not replace current classification methodologies. In this project, a small corpus of research publications from a technology domain is used to help construct the framework. The main means-ends relationships from the articles are manually extracted and represented in a graphical model showing which problems are approached, by which solutions proposed, and in which publications. Proposed solutions can lead to new problems which are in turn addressed by solutions proposed in other publications. A metamodel is derived to capture the important concepts and relationships relevant for this purpose. The metamodel, and the framework have undergone several iterations before finalization.

Aim: Despite the growing trend in offering online therapy to young people this area has received little attention to date. This project therefore aims to systematically explore work in this territory by investigating the types of goals that young people approach online services with, and the challenges and opportunities that online counsellors have experienced when working with them. Methods: Initially 1,137 client articulated goals which were collated by an online youth counselling service in England between December 2013 and July 2014. Secondly, semi-structured interviews were conducted with six online counsellors who have utilised a goal-based approach to therapy with young people. Both data strands were examined by utilising the Grounded Theory Methodology. Results: The goals young people brought into therapy were conceptualized under three core categories: (1) "Intra-personal goals", (2) "Inter-personal goals" and (3) "Goals on Self relating to others". Findings from the experience of online practitioners have provided four further core-categories: (1) "The impact of goals as an ingredient of the online therapy", (2) "The effect of virtual environment working towards goals", (3) "Key themes around youth goals", and (4) "The evolution of a practitioner's therapeutic identity". Discussion: The codified types of goals proved similar to the taxonomy of goals articulated within the Berne Inventory of Therapeutic Goals. Nuances related to the online environment and age group of the clients appeared to be present and are considered. In particular, the concept of goals on "Self relating to others" provided some interesting discussion points on the nature of services provided in both online and face-to-face youth services. The practitioner views echoed the published literature reflecting on the broader experiences of working with therapeutic goals. However the lack of research into the experiences of counsellors working with therapy goals is noted. Further reflection on the findings suggested a four stage working model for goal oriented online therapy. Reflections upon the limitations of the work, implications for therapists, researchers and service providers interested in online therapeutic work are outlined.

More and more challenging designs are required everyday in today¿s industries. The traditional trial and error procedure commonly used for mechanical parts design is not valid any more since it slows down the design process and yields suboptimal designs. For structural components, one alternative consists in using shape optimization processes which provide optimal solutions. However, these techniques require a high computational effort and require extremely efficient and robust Finite Element (FE) programs. FE software companies are aware that their current commercial products must improve in this sense and devote considerable resources to improve their codes. In this work we propose to use the Cartesian Grid Finite Element Method, cgFEM as a tool for efficient and robust numerical analysis. The cgFEM methodology developed in this thesis uses the synergy of a variety of techniques to achieve this purpose, but the two main ingredients are the use of Cartesian FE grids independent of the geometry of the component to be analyzed and an efficient hierarchical data structure. These two features provide to the cgFEM technology the necessary requirements to increase the efficiency of the cgFEM code with respect to commercial FE codes. As indicated in [1, 2], in order to guarantee the convergence of a structural shape optimization process we need to control the error of each geometry analyzed. In this sense the cgFEM code also incorporates the appropriate error estimators. These error estimators are specifically adapted to the cgFEM framework to further increase its efficiency. This work introduces a solution recovery technique, denoted as SPR-CD, that in combination with the Zienkiewicz and Zhu error estimator [3] provides very accurate error measures of the FE solution. Additionally, we have also developed error estimators and numerical bounds in Quantities of Interest based on the SPR-CD technique to allow for an efficient control of the quality of the numerical solution. Regarding error estimation, we also present three new upper error bounding techniques for the error in energy norm of the FE solution, based on recovery processes. Furthermore, this work also presents an error estimation procedure to control the quality of the recovered solution in stresses provided by the SPR-CD technique. Since the recovered stress field is commonly more accurate and has a higher convergence rate than the FE solution, we propose to substitute the raw FE solution by the recovered solution to decrease the computational cost of the numerical analysis. All these improvements are reflected by the numerical examples of structural shape optimization problems presented in this thesis. These numerical analysis clearly show the improved behavior of the cgFEM technology over the classical FE implementations commonly used in industry. / Cada d'¿a dise¿nos m'as complejos son requeridos por las industrias actuales. Para el dise¿no de nuevos componentes, los procesos tradicionales de prueba y error usados com'unmente ya no son v'alidos ya que ralentizan el proceso y dan lugar a dise¿nos sub-'optimos. Para componentes estructurales, una alternativa consiste en usar procesos de optimizaci'on de forma estructural los cuales dan como resultado dise¿nos 'optimos. Sin embargo, estas t'ecnicas requieren un alto coste computacional y tambi'en programas de Elementos Finitos (EF) extremadamente eficientes y robustos. Las compa¿n'¿as de programas de EF son conocedoras de que sus programas comerciales necesitan ser mejorados en este sentido y destinan importantes cantidades de recursos para mejorar sus c'odigos. En este trabajo proponemos usar el M'etodo de Elementos Finitos basado en mallados Cartesianos (cgFEM) como una herramienta eficiente y robusta para el an'alisis num'erico. La metodolog'¿a cgFEM desarrollada en esta tesis usa la sinergia entre varias t'ecnicas para lograr este prop'osito, cuyos dos ingredientes principales son el uso de los mallados Cartesianos de EF independientes de la geometr'¿a del componente que va a ser analizado y una eficiente estructura jer'arquica de datos. Estas dos caracter'¿sticas confieren a la tecnolog'¿a cgFEM de los requisitos necesarios para aumentar la eficiencia del c'odigo cgFEM con respecto a c'odigos comerciales. Como se indica en [1, 2], para garantizar la convergencia del proceso de optimizaci'on de forma estructural se necesita controlar el error en cada geometr'¿a analizada. En este sentido el c'odigo cgFEM tambi'en incorpora los apropiados estimadores de error. Estos estimadores de error han sido espec'¿ficamente adaptados al entorno cgFEM para aumentar su eficiencia. En esta tesis se introduce un proceso de recuperaci'on de la soluci'on, llamado SPR-CD, que en combinaci'on con el estimador de error de Zienkiewicz y Zhu [3], da como resultado medidas muy precisas del error de la soluci'on de EF. Adicionalmente, tambi'en se han desarrollado estimadores de error y cotas num'ericas en Magnitudes de Inter'es basadas en la t'ecnica SPR-CD para permitir un eficiente control de la calidad de la soluci'on num'erica. Respecto a la estimaci'on de error, tambi'en se presenta un proceso de estimaci'on de error para controlar la calidad del campo de tensiones recuperado obtenido mediante la t'ecnica SPR-CD. Ya que el campo recuperado es por lo general m'as preciso y tiene un mayor orden de convergencia que la soluci'on de EF, se propone sustituir la soluci'on de EF por la soluci'on recuperada para disminuir as'¿ el coste computacional del an'alisis num'erico. Todas estas mejoras se han reflejado en esta tesis mediante ejemplos num'ericos de problemas de optimizaci'on de forma estructural. Los resultados num'ericos muestran claramente un mejor comportamiento de la tecnolog'¿a cgFEM con respecto a implementaciones cl'asicas de EF com'unmente usadas en la industria. / Nadal Soriano, E. (2014). Cartesian grid FEM (cgFEM): High performance h-adaptive FE analysis with efficient error control. Application to structural shape optimization [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35620 / TESIS

Ces travaux de recherche ont pour objectif de contribuer au développement et à l'exploitation d'outils de vérification des problèmes de mécanique linéaires dans le cadre des méthodes de décomposition de domaine sans recouvrement. Les apports de cette thèse sont multiples : * Nous proposons d'améliorer la qualité des champs statiquement admissibles nécessaires à l'évaluation de l'estimateur par une nouvelle méthodologie de reconstruction des contraintes en séquentiel et par des optimisations du calcul de l'intereffort en cadre sous-structuré.* Nous démontrons des bornes inférieures et supérieures de l'erreur séparant l'erreur algébrique (due au solveur itératif) de l'erreur de discrétisation (due à la méthode des éléments finis) tant pour une mesure globale que pour une quantité d'intérêt. Cette séparation permet la définition d'un critère d'arrêt objectif pour le solveur itératif.* Nous exploitons les informations fournies par l'estimateur et les espaces de Krylov générés pour mettre en place une stratégie auto-adaptative de calcul consistant en une chaîne de résolution mettant à profit remaillage adaptatif et recyclage des directions de recherche. Nous mettons en application le pilotage du solveur par un objectif de précision sur des exemples mécaniques en deux dimensions. / This research work aims at contributing to the development of verification tools in linear mechanical problems within the framework of non-overlapping domain decomposition methods.* We propose to improve the quality of the statically admissible stress field required for the computation of the error estimator thanks to a new methodology of stress reconstruction in sequential context and thanks to optimizations of the computations of nodal reactions in substructured context.* We prove guaranteed upper and lower bounds of the error that separates the algebraic error (due to the iterative solver) from the discretization error (due to the finite element method) for both global error measure mentand goal-oriented error estimation. It enables the definition of a new stopping criterion for the iterative solver which avoids over-resolution.* We benefit the information provided by the error estimator and the Krylov subspaces built during the resolution to set an auto-adaptive strategy. This strategy consists in sequel of resolutions and takes advantage of adaptive remeshing and recycling of search directions .We apply the steering of the iterative solver by objective of precision on two-dimensional mechanical examples.