The maintenance of equipment has been an important issue for companies for many years. For systems with hidden or unrevealed failures (i.e., failures are not self-announcing), a common practice is to regularly inspect the system looking for such failures. Examples of these systems include protective devices, emergency devices, standby units, underwater devices etc. If no periodical inspection is scheduled, and a hidden failure has already occurred, severe consequences may result. Research on periodical inspection seeks to establish the optimal inspection interval (Failure Finding Interval) of systems to maximize availability and/or minimize expected cost. Research also focuses on important system parameters such as unavailability. Most research in this area considers non-negligible downtime due to repair/replacement but ignores the downtime caused by inspections. In many situations, however, inspection time is non-negligible. We address this gap by proposing an optimal failure finding interval (FFI) considering both non-negligible inspection time and repair/replacement time. A novel feature of this work is the development of models for both age-based and calendar-based inspection policies with random/constant inspection time and random/constant repair/replacement time. More specifically, we first study instantaneous availability for constant inspection and repair/replacement times. We start with the assumption of renewal of the system at each inspection. We then consider models with the assumption of renewal only after failure. We also develop limiting average availability models for random inspection and repair/replacement times, considering both age-based and calendar-based inspection policies. We optimize these availability models to obtain an optimal FFI in order to maximize the system’s availability. Finally, we develop several cost models for both age-based and calendar-based inspection policies with random inspection time and repair/replacement time. We formulate the model for constant inspection time and repair/replacement time as a special case. We investigate the optimization of cost models for each case to obtain optimal FFI in order to minimize the expected cost. The numerical examples and case study presented in the dissertation demonstrate the importance of considering non-negligible downtime due to inspection.

The primary aim of this thesis was to conduct a longitudinal study, to investigate the quality of life (QOL) in a large sample of people diagnosed with colorectal cancer (CRC), immediately post-diagnosis and one-year later. Various measures were utilised to capture the multifaceted concept of QOL, including psychological distress, satisfaction with life, positive affect and cancer-related quality of life. The investigation was conducted within Lazarus and Folkman’s stress and coping framework. Specifically, this research aimed to test the utility of the stress and coping framework in the context of CRC, and to explore the role of benefit-finding within the context of the stress and coping model components. One thousand, eight hundred participants (1078 men and 722 women) with a CRC diagnosis duration of 1 to 12 months, completed a telephone interview and written questionnaire, assessing demographics, disease/treatment characteristics, threat appraisal, social support, optimism, coping, benefit-finding and quality of life domains, at approximately five- and 12-months post-diagnosis. To identify CRC-specific coping strategies, the Coping with Colorectal Cancer measure was developed in the initial study. The eight factor structure was confirmed, and the subscales (Positive Perceptual Change; Religion/Spirituality; Rumination; Acceptance; Humour; Palliative; Seeking Social Support; and Lifestyle Reorganisation) found to have reliability and preliminary criterion-related validity within the context of the stress and coping framework. As predicted, regression analyses showed that, after controlling for demographics, disease/treatment characteristics and stress/coping variables, the coping subscales uniquely predicted Time 1 QOL outcomes, with Seeking Social Support continuing to predict Time 2 Positive Affect. In the second study, the benefit-finding domains specific to those with CRC were identified, and relationships with quality of life outcomes assessed, to determine the inclusion of benefit-finding in the path model. Based on completed data from 1757 of the initial 1800 participants, confirmatory factor analyses revealed three domains of benefit-finding: Personal Growth; Interpersonal Growth and Acceptance. As hypothesised, regressions analyses found that benefit-finding domains at Time 1 was associated with Time 1 QOL outcomes, specifically, Positive Affect and Cancer-related Quality of Life (both the aggregate score and its Social/Family, Functional and Colorectal Cancer-specific Well-being subscales). Time 1 Personal Growth also predicted Time 1 Psychological Distress. After controlling for Time 1 Positive Affect, Personal Growth continued to predict Time 2 Positive Affect. The final study drew on the results of the first two studies, which informed the coping strategies and benefit-finding domains to be included in regression analyses initially, and then, structural equation modelling. The final study included 1276 complete data sets of the initial 1800 participants. Parameters of the initial hypothesised model of the stress and coping framework, including relationships with benefit-finding (based on empirical findings) failed to fit the model to the data. After several revisions, the analysis revealed that the final model fit the data, where stress, coping and benefit-finding accounted for 63% of the variance in Time 1 QOL. The model showed that threat appraisal, coping resources, avoidant coping and benefit-finding directly impacted on Time 1 QOL, while threat appraisal, social support and approach coping directly impacted on benefit-finding. In this study, the approach coping strategies included in the path model could also be conceptualised as meaning-based coping strategies, as they appeared to facilitate a meaning-making process. However, benefit-finding, which some researchers have suggested is also a meaning-based coping strategy, had differential relationships with stress, coping and outcome variables, compared with the approach coping strategies. These results indicate that benefit-finding is an empirically distinct construct in the context of CRC. Finally, in this study, the impact of stress, coping and benefit-finding on Time 2 QOL, was indirect, being mediated by Time 1 QOL outcomes. The accumulated findings of these three studies have extended the cancer coping and benefit-finding research by revealing new relations between stress, coping and benefit-finding and QOL in a mixed-gender, older population with CRC. There are implications for measurement of, and theory building around benefit-finding. Finally, these studies inform the development of clinical interventions to enhance the quality of life in the short- and longer-term for individuals diagnosed with CRC.

The primary aim of this thesis was to conduct a longitudinal study, to investigate the quality of life (QOL) in a large sample of people diagnosed with colorectal cancer (CRC), immediately post-diagnosis and one-year later. Various measures were utilised to capture the multifaceted concept of QOL, including psychological distress, satisfaction with life, positive affect and cancer-related quality of life. The investigation was conducted within Lazarus and Folkman’s stress and coping framework. Specifically, this research aimed to test the utility of the stress and coping framework in the context of CRC, and to explore the role of benefit-finding within the context of the stress and coping model components. One thousand, eight hundred participants (1078 men and 722 women) with a CRC diagnosis duration of 1 to 12 months, completed a telephone interview and written questionnaire, assessing demographics, disease/treatment characteristics, threat appraisal, social support, optimism, coping, benefit-finding and quality of life domains, at approximately five- and 12-months post-diagnosis. To identify CRC-specific coping strategies, the Coping with Colorectal Cancer measure was developed in the initial study. The eight factor structure was confirmed, and the subscales (Positive Perceptual Change; Religion/Spirituality; Rumination; Acceptance; Humour; Palliative; Seeking Social Support; and Lifestyle Reorganisation) found to have reliability and preliminary criterion-related validity within the context of the stress and coping framework. As predicted, regression analyses showed that, after controlling for demographics, disease/treatment characteristics and stress/coping variables, the coping subscales uniquely predicted Time 1 QOL outcomes, with Seeking Social Support continuing to predict Time 2 Positive Affect. In the second study, the benefit-finding domains specific to those with CRC were identified, and relationships with quality of life outcomes assessed, to determine the inclusion of benefit-finding in the path model. Based on completed data from 1757 of the initial 1800 participants, confirmatory factor analyses revealed three domains of benefit-finding: Personal Growth; Interpersonal Growth and Acceptance. As hypothesised, regressions analyses found that benefit-finding domains at Time 1 was associated with Time 1 QOL outcomes, specifically, Positive Affect and Cancer-related Quality of Life (both the aggregate score and its Social/Family, Functional and Colorectal Cancer-specific Well-being subscales). Time 1 Personal Growth also predicted Time 1 Psychological Distress. After controlling for Time 1 Positive Affect, Personal Growth continued to predict Time 2 Positive Affect. The final study drew on the results of the first two studies, which informed the coping strategies and benefit-finding domains to be included in regression analyses initially, and then, structural equation modelling. The final study included 1276 complete data sets of the initial 1800 participants. Parameters of the initial hypothesised model of the stress and coping framework, including relationships with benefit-finding (based on empirical findings) failed to fit the model to the data. After several revisions, the analysis revealed that the final model fit the data, where stress, coping and benefit-finding accounted for 63% of the variance in Time 1 QOL. The model showed that threat appraisal, coping resources, avoidant coping and benefit-finding directly impacted on Time 1 QOL, while threat appraisal, social support and approach coping directly impacted on benefit-finding. In this study, the approach coping strategies included in the path model could also be conceptualised as meaning-based coping strategies, as they appeared to facilitate a meaning-making process. However, benefit-finding, which some researchers have suggested is also a meaning-based coping strategy, had differential relationships with stress, coping and outcome variables, compared with the approach coping strategies. These results indicate that benefit-finding is an empirically distinct construct in the context of CRC. Finally, in this study, the impact of stress, coping and benefit-finding on Time 2 QOL, was indirect, being mediated by Time 1 QOL outcomes. The accumulated findings of these three studies have extended the cancer coping and benefit-finding research by revealing new relations between stress, coping and benefit-finding and QOL in a mixed-gender, older population with CRC. There are implications for measurement of, and theory building around benefit-finding. Finally, these studies inform the development of clinical interventions to enhance the quality of life in the short- and longer-term for individuals diagnosed with CRC.

Thesis (M.A.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

学位授与大学：京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2856号 ; 請求記号: 新制/工/1420 ; 整理番号: 25541 / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13385号 / 工博第2856号 / 新制||工||1420(附属図書館) / 25541 / UT51-2007-Q786 / 京都大学大学院工学研究科建築学専攻 / (主査)教授 加藤 直樹, 教授 上谷 宏二, 准教授 大﨑 純 / 学位規則第4条第1項該当

Este trabalho define um ambiente que auxilia o usuário a determinar as raízes complexas de um polinômio, dados apenas seus coeficientes complexos. Para tanto é definida uma interface que habilita a comunicação e a apresentação de resultados de forma mais expressiva do que as habitualmente usadas, permitindo que o usuário perceba mais rapidamente as informações que a ferramenta lhe apresenta. Para capacitar o usuário a determinar as soluções o sistema faz uso de uma abordagem baseada em imagens, obtidas a partir da interpretação do polinômio sendo estudado como se fosse uma superfície originada por uma função de dual variáveis. Através do uso de imagens o usuário pode orientar o sistema para determinar as soluções de seu interesse particular, e pode adicionalmente perceber de forma muito clara detalhes do polinômio que não são apresentados por outras ferramentas. São definidas operações que facilitam a manipulação das imagens obtidas, podendo-se efetuar uma serie de computações que eventualmente dispensam os métodos de determinação numérica de raízes, obtendo-se de uma forma alternativa possíveis aproximações para as soluções. Esta abordagem apoiada em imagens é muito útil na determinação de raízes em regiões onde a avaliação do polinômio se mostra instável ou sujeita a erros grosseiros, como por exemplo raízes múltiplas. Quando são geradas imagens pode ser percebida claramente a presença de erros de avaliação, permitindo que o usuário tome a atitude que julgar adequada. Outros sistemas não permitem que tais instabilidades sejam notadas, fornecendo respostas que podem lido ter qualquer nexo com a realidade. Para uso na ferramenta que implementa a solução proposta, existe uma serie de comandos definidos que capacitam o usuário a fazer quaisquer operações de seu interesse. Estes comandos foram já testados no período da implementação do sistema e permitem que sejam feitas operações sobre o polinômio, as imagens geradas e as raízes determinadas. Em todo o projeto do sistema existe a preocupação de tornar claro o que está acontecendo a cada momento com o polinômio ou com os dados dele obtidos, para que o usuário não se canse em demasia, seja interpretando dados do sistema ou procurando decidir o que fazer em seguida. Assim, o use da ferramenta d bastante natural, e tenta atingir a intuição daqueles que a irão usar. Exemplos são apresentados, bem como descrições dos comandos utilizados na interface. De especial interesse são os algoritmos usados na construção das imagens, pois estes permitem uma grande economia nas avaliações do polinômio quando da geração das cenas, reduzindo sobremaneira o tempo de espera do usuário. Quanto as imagens, são fornecidos três tipos de representações: imagens coloridas em duas dimensões, curvas de nível e curvas de sinal. O uso de três dimensões nas imagens foi descartado, e as razões para tanto estão descritas no texto. Todos os tipos de imagens permitem que se determine e identifique com facilidade as soluções desejadas, e são construídas a partir de uma transformação sobre o polinômio original. Esta transformação é explicada em detalhe no transcorrer do texto. / This work describes an environment that helps the user to find the complex solutions of a polynomial, given its coefficients. To do so, a quite expressive user interface is defined providing easy communication between man and machine and also allowing users to perceive much more rapidly the informations given by the tool. The system uses an image-based interface, obtained from a two-variable surface defined by the polynomial. By using these pictures, it is possible to direct the tool, finding any solutions of special meaning to the user. In addition, some details and features of the polynomial can be very easily seen. To manipulate images a set of operations was defined, and this set has so many features that the use of some operations can even avoid the effort of numerically computing the zeros of the polynomial, also reducing the numerical error embedded in these computations. This image-based approach is very useful when finding domains where the evaluation of the polynomial is unstable or prone to errors, e. g., near multiple roots. In pictures, any evaluation problems are easily detected, and the user can decide how to take the answers given by the system. Other tools usually do not provide any means to detect such behavioral oscillations, and can give nonsense answers. There is a set of commands embedded on the tool that implements the proposed solution, and they allow the user to perform any operations of his (her) interest. Such commands were tested at implementation time, and all were useful at some moment. They perform operations on the polynomial, on the pictures and on the detected zeros. All over the design phase there was the care of making clear what is happening to the polynomial or any data, so that the user can always work without being stressed by trying to find out what is happening. So, we try to build a natural approach to this interfacing problem, trying to reach user's intuition. Examples and descriptions of the commands are given, and also there is a description of a quite important algorithm, the one that builds the pictures themselves. This algorithm needs quite few evaluations of the function to generate pictures, thus reducing the waiting times. For the images, there are three presentation types: color images in two dimensions, height curves or signal curves. Three-dimensional pictures were discarded, and the reasons to such decision are described on the text. All kinds of images provide easy and simple identification of solutions. The images are produced from a simple transformation of the starting polynomial. This transformation is also explained in detail.

Cette thèse portant sur l’analyse des pratiques d’information chez la population jeune en France vise à montrer comment leurs habitudes en matière de recherche et de consommation d’information (journalistique) ont évolué, ont été transformées et modifiées avec les moyens numériques. Il s’agit par ailleurs d’une étude comparative des usages des moyens d’accès à l’information, établissant un contraste entre les médias dits traditionnels (la télévision, la radio et la presse papier) et Internet. Dans cette optique, l’essentiel de notre réflexion est de tenter de savoir et comprendre comment les jeunes s’approprient du web comme outil communicationnel dans un rapport global aux autres médias. L’information numérique a-t-elle provoqué une mutation dans les pratiques d’information au quotidien ? Notre recherche a permis de relever quelques transformations dans les pratiques d’informations des jeunes : l’essentiel de la consommation d’information se fait par internet ; ils ont tendance à délaisser la lecture de la presse papier en faveur de la presse en ligne compte tenu de la gratuité des informations ; la recherche et la consommation des sites d’information alternative restent une pratique extrêmement minoritaire ; les pratiques informationnelles des jeunes tendent à mêler divertissement et information d’actualité humoristique. En définitive, cette thèse a permis de clarifier le rapport des jeunes à l’information, la manière dont ils s’informent en ligne au travers des supports numériques. Elle a aussi permis de réfuter l’idée selon laquelle les jeunes ne s’intéressent plus à l’actualité et la politique. Bien au contraire, la gratuité des informations sur le web, la facilité et les nouvelles façons de présenter l’information (information divertissante) ont considérablement élargi la capacité des jeunes à connaître le fonctionnement du monde qui les entoure / This thesis on the analysis of information practices among the young population in France aims to show how their habits in research and information consumption (Journalistic) have evolved, have been transformed and modified with digital means. This is also a comparative study of the uses of means of access to information, establishing a contrast between so-called traditional media (television, radio and the printed press) and Internet. In this sense, much of our thinking is to try to know and understand how young people take ownership of the web as a communicative tool in a global comparison with other media. Does Digital information has caused a change in the information practices in everyday life? Our research has identified some changes in youth information practices: most of the information consumption is through Internet; they tend to neglect reading the newspapers in favour of online media because the information is there massively Free; Research and consumption of alternative news sites remain an extremely minority practice; The information practices of young people tend to mix entertainment and humorous topical information. Ultimately, this thesis has clarified the relation of youth to information, the way they inform online through digital media. It also helped to refute the idea that young people are no longer interested in news and politics. On the contrary, free information on the web, the ease and new ways of presenting information (entertainment news) have greatly expanded the ability of young people to know how the world around them

Este trabalho define um ambiente que auxilia o usuário a determinar as raízes complexas de um polinômio, dados apenas seus coeficientes complexos. Para tanto é definida uma interface que habilita a comunicação e a apresentação de resultados de forma mais expressiva do que as habitualmente usadas, permitindo que o usuário perceba mais rapidamente as informações que a ferramenta lhe apresenta. Para capacitar o usuário a determinar as soluções o sistema faz uso de uma abordagem baseada em imagens, obtidas a partir da interpretação do polinômio sendo estudado como se fosse uma superfície originada por uma função de dual variáveis. Através do uso de imagens o usuário pode orientar o sistema para determinar as soluções de seu interesse particular, e pode adicionalmente perceber de forma muito clara detalhes do polinômio que não são apresentados por outras ferramentas. São definidas operações que facilitam a manipulação das imagens obtidas, podendo-se efetuar uma serie de computações que eventualmente dispensam os métodos de determinação numérica de raízes, obtendo-se de uma forma alternativa possíveis aproximações para as soluções. Esta abordagem apoiada em imagens é muito útil na determinação de raízes em regiões onde a avaliação do polinômio se mostra instável ou sujeita a erros grosseiros, como por exemplo raízes múltiplas. Quando são geradas imagens pode ser percebida claramente a presença de erros de avaliação, permitindo que o usuário tome a atitude que julgar adequada. Outros sistemas não permitem que tais instabilidades sejam notadas, fornecendo respostas que podem lido ter qualquer nexo com a realidade. Para uso na ferramenta que implementa a solução proposta, existe uma serie de comandos definidos que capacitam o usuário a fazer quaisquer operações de seu interesse. Estes comandos foram já testados no período da implementação do sistema e permitem que sejam feitas operações sobre o polinômio, as imagens geradas e as raízes determinadas. Em todo o projeto do sistema existe a preocupação de tornar claro o que está acontecendo a cada momento com o polinômio ou com os dados dele obtidos, para que o usuário não se canse em demasia, seja interpretando dados do sistema ou procurando decidir o que fazer em seguida. Assim, o use da ferramenta d bastante natural, e tenta atingir a intuição daqueles que a irão usar. Exemplos são apresentados, bem como descrições dos comandos utilizados na interface. De especial interesse são os algoritmos usados na construção das imagens, pois estes permitem uma grande economia nas avaliações do polinômio quando da geração das cenas, reduzindo sobremaneira o tempo de espera do usuário. Quanto as imagens, são fornecidos três tipos de representações: imagens coloridas em duas dimensões, curvas de nível e curvas de sinal. O uso de três dimensões nas imagens foi descartado, e as razões para tanto estão descritas no texto. Todos os tipos de imagens permitem que se determine e identifique com facilidade as soluções desejadas, e são construídas a partir de uma transformação sobre o polinômio original. Esta transformação é explicada em detalhe no transcorrer do texto. / This work describes an environment that helps the user to find the complex solutions of a polynomial, given its coefficients. To do so, a quite expressive user interface is defined providing easy communication between man and machine and also allowing users to perceive much more rapidly the informations given by the tool. The system uses an image-based interface, obtained from a two-variable surface defined by the polynomial. By using these pictures, it is possible to direct the tool, finding any solutions of special meaning to the user. In addition, some details and features of the polynomial can be very easily seen. To manipulate images a set of operations was defined, and this set has so many features that the use of some operations can even avoid the effort of numerically computing the zeros of the polynomial, also reducing the numerical error embedded in these computations. This image-based approach is very useful when finding domains where the evaluation of the polynomial is unstable or prone to errors, e. g., near multiple roots. In pictures, any evaluation problems are easily detected, and the user can decide how to take the answers given by the system. Other tools usually do not provide any means to detect such behavioral oscillations, and can give nonsense answers. There is a set of commands embedded on the tool that implements the proposed solution, and they allow the user to perform any operations of his (her) interest. Such commands were tested at implementation time, and all were useful at some moment. They perform operations on the polynomial, on the pictures and on the detected zeros. All over the design phase there was the care of making clear what is happening to the polynomial or any data, so that the user can always work without being stressed by trying to find out what is happening. So, we try to build a natural approach to this interfacing problem, trying to reach user's intuition. Examples and descriptions of the commands are given, and also there is a description of a quite important algorithm, the one that builds the pictures themselves. This algorithm needs quite few evaluations of the function to generate pictures, thus reducing the waiting times. For the images, there are three presentation types: color images in two dimensions, height curves or signal curves. Three-dimensional pictures were discarded, and the reasons to such decision are described on the text. All kinds of images provide easy and simple identification of solutions. The images are produced from a simple transformation of the starting polynomial. This transformation is also explained in detail.

O Método das Densidades de Força (MDF), proposto primeiramente por Linkwitz (1971) e depois por Scheck (1974), é uma alternativa conveniente para encontrar configurações de redes de cabos e membranas, uma vez que fornece geometrias viáveis com uma única análise linear de equilíbrio. O Método das Densidades de Força Natural (MDFN) é uma extensão do MDF para busca de formas de estruturas de membranas, que preserva a linearidade do método original e supera suas dificuldades em lidar com malhas irregulares. Foi primeiramente sugerido por Pauletti em 2006, baseado no elemento triangular de membrana introduzido por Argyris em 1974. O Método tem sido aplicado com sucesso em vários projetos. O MDFN original requer o uso de malhas compostas exclusivamente por elementos triangulares. Esta dissertação apresenta uma extensão do método para elementos quadrangulares, considerando um elemento composto por quatro subelementos triangulares. Mesmo que a ideia básica seja muito simples, algumas dificuldades surgem do fato de que nesta abordagem, o elemento de quatro nós pode não conter todos os nós em um mesmo plano, especialmente no caso de superfícies anticlásticas, sendo que não existe um campo de tensões bem definido para o interior do elemento. O trabalho compara alguns resultados obtidos com malhas exclusivamente triangulares, como requerido pelo método original, com os resultados obtidos com o elemento quadrangular proposto, discutindo a forma de combinar as tensões dos subelementos triangulares para originar as tensões atuantes no elemento quadrangular. Os modelos obtidos no MDFN são inseridos no programa Ansys, e os resultados são comparados para analisar a viabilidade da solução proposta e dos resultados obtidos por meio desta. / The Force Density Method (FDM), first proposed by Linkwitz(1971) and after by Scheck(1974), is a convenient alternative for finding configurations of cable nets and membranes, since it provides viable geometries in a single linear equilibrium analysis. The Natural Force Density Method (NFDM) is an extension of the FDM to the shape finding of membrane structures, which preserves the linearity of the original method and overcomes the difficulties of the original method to deal with irregular meshes. It was first suggested by Pauletti in 2006, based on a triangular membrane element introduced by Argyris in 1974. The method has been successfully applied to several design cases. The original NFDM required the use of meshes composed exclusively of triangular elements. This text presents an extension of the method to quadrangular elements, considering an equivalent assemblage of flat triangular elements. Even if the basic idea is very simple, some difficulties arise from the fact that in this approach, the quadrangular element can have a non-flat configuration, especially in the anticlastic shape, and there is not a know stress field into the interior of the element. The text compares several results obtained with fully triangulated meshes, as required by the original NFDM, to those obtained with the proposed quadrangular element, discussing the different strategies that have been explored to map stresses from the internal triangular mesh to the four nodes of the element. The models obtained in the NFDM are inserted in software Ansys and the results compared to approve the solution and the results obtained.

Este trabalho define um ambiente que auxilia o usuário a determinar as raízes complexas de um polinômio, dados apenas seus coeficientes complexos. Para tanto é definida uma interface que habilita a comunicação e a apresentação de resultados de forma mais expressiva do que as habitualmente usadas, permitindo que o usuário perceba mais rapidamente as informações que a ferramenta lhe apresenta. Para capacitar o usuário a determinar as soluções o sistema faz uso de uma abordagem baseada em imagens, obtidas a partir da interpretação do polinômio sendo estudado como se fosse uma superfície originada por uma função de dual variáveis. Através do uso de imagens o usuário pode orientar o sistema para determinar as soluções de seu interesse particular, e pode adicionalmente perceber de forma muito clara detalhes do polinômio que não são apresentados por outras ferramentas. São definidas operações que facilitam a manipulação das imagens obtidas, podendo-se efetuar uma serie de computações que eventualmente dispensam os métodos de determinação numérica de raízes, obtendo-se de uma forma alternativa possíveis aproximações para as soluções. Esta abordagem apoiada em imagens é muito útil na determinação de raízes em regiões onde a avaliação do polinômio se mostra instável ou sujeita a erros grosseiros, como por exemplo raízes múltiplas. Quando são geradas imagens pode ser percebida claramente a presença de erros de avaliação, permitindo que o usuário tome a atitude que julgar adequada. Outros sistemas não permitem que tais instabilidades sejam notadas, fornecendo respostas que podem lido ter qualquer nexo com a realidade. Para uso na ferramenta que implementa a solução proposta, existe uma serie de comandos definidos que capacitam o usuário a fazer quaisquer operações de seu interesse. Estes comandos foram já testados no período da implementação do sistema e permitem que sejam feitas operações sobre o polinômio, as imagens geradas e as raízes determinadas. Em todo o projeto do sistema existe a preocupação de tornar claro o que está acontecendo a cada momento com o polinômio ou com os dados dele obtidos, para que o usuário não se canse em demasia, seja interpretando dados do sistema ou procurando decidir o que fazer em seguida. Assim, o use da ferramenta d bastante natural, e tenta atingir a intuição daqueles que a irão usar. Exemplos são apresentados, bem como descrições dos comandos utilizados na interface. De especial interesse são os algoritmos usados na construção das imagens, pois estes permitem uma grande economia nas avaliações do polinômio quando da geração das cenas, reduzindo sobremaneira o tempo de espera do usuário. Quanto as imagens, são fornecidos três tipos de representações: imagens coloridas em duas dimensões, curvas de nível e curvas de sinal. O uso de três dimensões nas imagens foi descartado, e as razões para tanto estão descritas no texto. Todos os tipos de imagens permitem que se determine e identifique com facilidade as soluções desejadas, e são construídas a partir de uma transformação sobre o polinômio original. Esta transformação é explicada em detalhe no transcorrer do texto. / This work describes an environment that helps the user to find the complex solutions of a polynomial, given its coefficients. To do so, a quite expressive user interface is defined providing easy communication between man and machine and also allowing users to perceive much more rapidly the informations given by the tool. The system uses an image-based interface, obtained from a two-variable surface defined by the polynomial. By using these pictures, it is possible to direct the tool, finding any solutions of special meaning to the user. In addition, some details and features of the polynomial can be very easily seen. To manipulate images a set of operations was defined, and this set has so many features that the use of some operations can even avoid the effort of numerically computing the zeros of the polynomial, also reducing the numerical error embedded in these computations. This image-based approach is very useful when finding domains where the evaluation of the polynomial is unstable or prone to errors, e. g., near multiple roots. In pictures, any evaluation problems are easily detected, and the user can decide how to take the answers given by the system. Other tools usually do not provide any means to detect such behavioral oscillations, and can give nonsense answers. There is a set of commands embedded on the tool that implements the proposed solution, and they allow the user to perform any operations of his (her) interest. Such commands were tested at implementation time, and all were useful at some moment. They perform operations on the polynomial, on the pictures and on the detected zeros. All over the design phase there was the care of making clear what is happening to the polynomial or any data, so that the user can always work without being stressed by trying to find out what is happening. So, we try to build a natural approach to this interfacing problem, trying to reach user's intuition. Examples and descriptions of the commands are given, and also there is a description of a quite important algorithm, the one that builds the pictures themselves. This algorithm needs quite few evaluations of the function to generate pictures, thus reducing the waiting times. For the images, there are three presentation types: color images in two dimensions, height curves or signal curves. Three-dimensional pictures were discarded, and the reasons to such decision are described on the text. All kinds of images provide easy and simple identification of solutions. The images are produced from a simple transformation of the starting polynomial. This transformation is also explained in detail.