• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 513
  • 232
  • 186
  • 72
  • 38
  • 22
  • 17
  • 14
  • 13
  • 13
  • 11
  • 10
  • 9
  • 7
  • 7
  • Tagged with
  • 1332
  • 121
  • 113
  • 100
  • 98
  • 98
  • 97
  • 88
  • 67
  • 63
  • 61
  • 60
  • 59
  • 52
  • 51
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Métodos de Projeção Multidimensional

Col Júnior, Alcebíades Dal 10 May 2013 (has links)
Made available in DSpace on 2016-12-23T14:34:47Z (GMT). No. of bitstreams: 1 Alcebiades Dal Col Junior - Parte 01.pdf: 9389564 bytes, checksum: 9f9b7659588a24bb015e4032ebe84dd1 (MD5) Previous issue date: 2013-05-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O problema que estamos interessados em resolver provém de uma área do conhecimento denominada visualização de dados. Nos nossos estudos, grupos de objetos são analisados para produzir os dados de entrada do nosso problema, cada um dos objetos é representado por atributos, temos assim uma lista de atributos para cada objeto. A ideia é representar, através dessas listas de atributos, os objetos através de pontos em R2 para que possamos realizar um estudo do grupo de objetos. Como dissemos cada objeto é representado por uma lista de atributos, esta pode ser interpretada como um ponto de um espaço multidimensional. Por exemplo, se são considerados m atributos valorados para todos os objetos podemos interpretá-los como sendo pontos de um espaço de imensão m, ou m dimensional. Mas, queremos produzir uma visualização dos dados na tela do computador através de pontos em R2, realiza-se então um processo conhecido como projeção multidimensional, que é a obtenção de pontos em um espaço de baixa dimensão que represente pontos de um espaço de alta dimensão preservando relações de vizinhaça tanto quanto possível. Diversos métodos de projeção multidimensional são encontrados na literatura. Neste trabalho, estudamos e implementamos os métodos NNP, Force, LSP, PLP e LAMP. Estes métodos abordam o problema de diferentes formas: geometricamente; sistemas lineares, em particular, sistemas laplacianos; e mapeamentos ortogonais afins. As listas de atributos associadas aos grupos de objetos recebem o nome de conjuntos de dados. Dois dos conjuntos de dados abordados neste trabalho apresentam tendências de agrupamento conhecidas a priori, portanto foram utilizados para dar credibilidade as nossas implementações dos métodos. Outros dois conjuntos de dados são estudados e esses não eram dotados de tal característica, os métodos de projeção multidimensional são então utilizados para definir tendências de agrupamento para esses dois conjuntos de dados OBS: Os Gráficos de dispersão das projeções dos conjuntos de dados Iris, Wine, Housing (de cima para baixo) através dos métodos NNP, Force, LSP, PLP e LAMP (da esquerda para a direita) não foram anexados por terem mais de 2 KB, excedendo o limite do site. / The problem we are interested in solving comes from a area of knowledge called data visualization. In our studies, groups of objects are analyzed to produce the input data of our problem, each object is represented by attributes, have so a list of attributes for each object. The idea is to represent, through these lists of attributes, objects through points in R2 so that we can conduct a group of objects. As we said each object is represented by a list of attributes, this may be interpreted as a point of a multidimensional space. For example, if they are considered m valued attributes for all objects can interpret them as points in a space of dimension m, or m-dimensional. But we want to produce a visualization of the data on the computer screen through points in R2, it was then performs a process known as multidimensional projection, that is obtaining points in a low dimensional space representing points in a high dimensional space preserving neighborhood relations as much as possible. Various methods of multidimensional projection are found in the literature. In this work, study and implement methods NNP, Force, LSP, PLP and LAMP. These methods deal with the problem in different ways: geometrically; linear systems, in particular, laplacian systems; and mappings related orthogonal. The lists of attributes associated with the groups of objects are called dataset. Two sets of data in this paper present trends grouping known a priori, therefore were used to give credibility to our implementations of the methods. Two other data set are studied and these were not provided with such feature, the methods of multidimensional projection are then used to define trends grouping for these two data sets
202

Discurso e sujeito : a representação do ensino público nos textos dos alunos de ensino médio

Lilian Mobrizi Silva Werlang 25 April 2008 (has links)
Este estudo nasceu do interesse em averiguar os motivos da falta de interesse dos alunos do nível de ensino médio pela Escola, portanto, pela educação formal. A hipótese para o desinteresse dos alunos pela Escola é que o método avaliativo das escolas públicas do Estado de São Paulo (Progressão continuada) não avalia a aprendizagem, o que não os motiva a estudarem e, por conseguinte, a se interessarem pela Escola. O objetivo deste estudo foi verificar, na materialidade lingüística do discurso de alunos de nível de ensino médio, indícios de que acreditam que a falta de avaliação nas escolas públicas, em relação ao Estado de São Paulo, é um fator que desmotiva o interesse pelo estudo e, portanto, pela Escola. Considerando que os discentes não são seres cartesianos, analíticos e que são constituídos sóciohistoricamente e, portanto, pela ideologia e, ainda, que o discurso materializa tal constituição, e crendo na inextrincabilidade entre discurso e sujeito, convocando como pilares teóricos a Análise do Discurso de linha francesa e Psicanálise lacaniana, no que diz respeito ao conceito freudiano de sublimação. O corpus de pesquisa foi coletado em uma escola pública, no bairro Jardim Araretama, em Pindamonhangaba-SP, por meio de excertos de textos dissertativos, produzidos pelos alunos do Ensino Médio. As perguntas de pesquisa norteadoras foram: 1- Quais são as representações ou imagens que os alunos de nível de ensino médio de escolas da rede pública de ensino fazem da Escola? 2- Quais são as representações ou imagem que fazem de aluno de escolas da rede pública, isto é, sobre si mesmo? 3- Quais são as representações ou imagem que fazem de avaliação? Os resultados da pesquisa revelaram que: 1) As representações que fazem da escola pública é daquela que idealizam, mas a qual não têm acesso; 2) As representações que fazem sobre si são de que constituem a parcela da sociedade que não tem acesso ao saber de qualidade e, determinados pela memória discursiva de divisão social do saber e de interdiscursos judaico-cristãos e estóicos, buscam culpados pelo insucesso escolar; 3) As representações que fazem sobre o método avaliativo do Estado de São Paulo (Progressão continuada) instauram-se a partir da percepção de que, tal método, tirou a validade da educação, promovendo o desinteresse pelo estudo e, por conseguinte, pela Escola, por parte dos discentes, uma vez que só estuda quem é avaliado. Os resultados demonstraram, ainda, que, para além da busca de culpados pelo insucesso escolar, os discentes sublimam a educação de qualidade, procurando atenuar a dor de não terem a qualidade de ensino que almejam, bem como projetam suas supostas realizações nas gerações vindouras. / This study was of interest to ascertain the reasons for the lack of interest of students in the level of high school by school, so the formal education. The hypothesis for the lack of students by the school is that the evaluative method of the public schools of the State of Sao Paulo (Progress continued) does not evaluate the learning, which is not the motivation to study and, therefore, is interested by the School. The purpose of this study was to verify, in the materiality of language speech of students, level of education, evidence that believe that the lack of evaluation in public schools in the state of Sao Paulo, is a factor that discourages interest in the study and therefore by the School. Whereas the students are not being cartesianos, analytical and which consist socio-historically, and therefore by ideology, and that the speech materialized this constitution, and believing in inextrincabilidade between speech and subject, calling pillars as a theoretical analysis of Speech-line French and Lacanian psychoanalysis, with regard to the concept of Freudian sublimation. The body of research was collected in a public school in the neighborhood Garden Araretama in Pindamonhangaba-SP, through excerpts of texts dissertativos, produced by the students of high school. The questions guiding the search were: 1 - What are the representations or images that the students of high school level of the public network of schools of education are the School? 2 - What are the representations or images that make student of the public schools, that is, about themselves? 3 - What are the representations or images that make assessment? The survey results showed that: 1) the representations that are of public schools is that which idealizam, but which do not have access, 2) the representations that are about you are that form the part of society that has no access to knowledge quality and, determined by the memory of discursive social division of knowledge and interdiscursos Judeo-Christian and estóicos, looking guilty by school failure, 3) the representations that are on the evaluative method of the State of Sao Paulo (Progress continued) introduce themselves from the perception that such method, took the validity of education, promoting the disinterest by the study, and therefore the school, on the part of students, since only those studies is evaluated. The results showed also that, in addition to the search for the culprits school failure, the students sublimate the education of quality, seeking alleviate the pain of not having the quality of education that aim, as well as project their "supposed" achievements in the generations come.
203

Estimativa da energia de lançamento das argamassas projetadas por spray a ar comprimido. / Estimation of projection energy of mortars sprayed by compressed air.

Heloísa Cristina Fernandes 26 March 2007 (has links)
O revestimento de argamassa é um componente comum das fachadas dos edifícios brasileiros. Sua aderência à base é um fator determinante para seu adequado desempenho, pois a queda de placas de revestimento pode resultar em falhas funcionais e estéticas e até em acidentes fatais. Está provado que a aderência do revestimento depende da combinação entre o comportamento reológico da argamassa e a energia com que foi lançada à base durante a aplicação. Sabe-se, também, que a introdução da técnica de aplicação de argamassa por spray a ar comprimido aumentou a aderência dos revestimentos com relação à aplicação manual. Não se conhecia ainda a energia empregada por esse tipo de equipamento e os fatores que exerceriam influência nesse sistema de projeção. Este trabalho apresenta o desenvolvimento de uma metodologia simples que estima a energia de lançamento dos projetores a ar comprimido e estuda experimentalmente os fatores importantes para a projeção, tais como a pressão do ar comprimido e o comportamento reológico de diversas composições de argamassa preparadas com dois teores de água em diferentes equipamentos do mercado brasileiro. Foram estimadas, também, a produtividade, a partir do tempo necessário para esvaziamento do projetor, e as perdas potenciais de cada combinação. Dados experimentais mostraram que a energia de lançamento, empregada pelos equipamentos estudados, para as argamassas ensaiadas variou de 2 a 16 J/kg, as perdas potenciais estimadas variaram de 1% a 25% e o intervalo de tempo para projeção medido foi de 5 a 20 s. / Mortar rendering is commonly applied to Brazilian buildings façades. Its adherence to the base is an important enabler for its adequate performance, since the fall of not properly applied rendering plates may result in functional and esthetical failures and even in fatalities. It is known that the mortar rendering bond strength depends on the combination between its rheological behavior and the energy (or speed) utilized in its projection. It has also already been demonstrated that the mortar projected by spray equipment propelled by compressed air have better bond strength than the same mortar projected manually. However, the projection energy of the equipment and the related parameters that may influence this process has not been measured yet. This paper aims to develop a simple methodology to measure the projection energy provided by the air spray equipment and also the role of the parameters that affect this process, such as air pressure values and rheological behavior of several mortar formulations prepared with distinct water contents being projected by different equipments commonly found in the Brazilian market. The process productivity, by means of the time necessary to empty the projector mortar reservoir, and the potential material waste of each combination were also studied. A set of experimental data demonstrated that the projection energy provided by the studied equipments to the different mortar formulations presented a variation range from 2 to 16 J/kg, an estimated potential material losses ranged from 1% to 25% and a projection time from 5 to 20 s.
204

Projeção e avaliação do consumo de combustíveis fósseis para a geração de eletricidade na Venezuela : Projection of fossil fuels consumption for electricity generation in Venezuela / Projection of fossil fuels consumption for electricity generation in Venezuela

Vidoza Guillen, Jorge Alejandro, 1988- 24 August 2018 (has links)
Orientador: Waldyr Luiz Ribeiro Gallo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T19:50:08Z (GMT). No. of bitstreams: 1 VidozaGuillen_JorgeAlejandro_M.pdf: 6817089 bytes, checksum: a261816320a3076eeb75253558a35d02 (MD5) Previous issue date: 2014 / Resumo: O objetivo principal deste trabalho é analisar os impactos futuros da aplicação de políticas energéticas mais eficientes no consumo de combustíveis fósseis para a geração de eletricidade na Venezuela. Os recursos principais utilizados na indústria elétrica são: gás natural, óleo diesel e óleo combustível. Esta análise foi feita projetando o desenvolvimento a médio prazo do setor elétrico em um horizonte de tempo de quinze anos. Diferentes cenários de crescimento econômico e mudanças tecnológicas foram assumidos a fim de realizar essas projeções. A ferramenta de simulação usada foi o programa de planejamento energético LEAP. Após simular um esquema de demanda e fixar as características de desenvolvimento de cada cenário, obtiveram-se os resultados de consumo e disponibilidade. O cenário de alto crescimento econômico e baixa eficiência (CRE) apresenta uma importação de gás natural de 15% da demanda total. Por outro lado, o cenário de baixo crescimento econômico e baixa eficiência (BAS), além de importações de gás natural, apresenta uma importação direta de eletricidade de 8% da demanda total. Estes cenários com baixa eficiência deixariam a Venezuela vulnerável em termos de segurança energética. Devido ao grande risco que apresentam esses cenários, é mais provável que ocorra maior investimento na produção e exploração interna de recursos energéticos, que investimentos em infraestrutura para importação. O óleo diesel apresenta cenários menos divergentes e mais independentes das hipóteses utilizadas. O consumo de óleo combustível depende em grande parte da disponibilidade dos outros dois e da conjuntura econômica, porque, para deixar de utilizar este recurso são necessárias mudanças mais estruturais nas usinas de geração e refinarias. Deve-se alcançar uma utilização mais eficiente dos combustíveis líquidos, que atenue também o déficit temporário de gás natural. O incremento da eficiência nesses processos é vital para a economia venezuelana já que poderia incrementar a quantidade de petróleo cru disponível para a exportação / Abstract: The main goal of this work was to make a prospective analysis on the impacts of efficient energy policies application, regarding the fossil fuel consumption for electricity generation in Venezuela. The main fossil resources used for the electric power industry are: natural gas, diesel and fuel oil. The analysis was done by projecting the middle-term development of the electrical sector in a fifteen year time horizon. Different conditions of economic growth and technology were assumed in order to carry out these projections. Energy planning software LEAP was the simulation tool used in this study. Results on consumption and availability were finally obtained after simulating a demand scheme and fixing the development characteristics of every scenario. The high-economic growth and low-efficiency scenario (CRE) results in gas imports that correspond to 15% of total demand. The low-economic growth and low-efficiency scenario (BAS), besides of resulting in natural gas imports, also presents electrical energy imports of 8% of the total demand. These low-efficiency scenarios would make Venezuela vulnerable in terms of energy security. Because of the high risks presented in these scenarios, investments in the inner production and exploitation of energy resources are more likely to happen, rather than investments in imports infrastructure, such as ports, piping or power transmission connections. Diesel oil presents less divergent and more independent scenarios, for the chosen hypotheses. Consumption of fuel oil depends on the availability of the other analyzed fuels. To reduce the consumption of this resource, more structural changes would be needed, such as retrofitting of oil refineries and power generation units. A more efficient use of liquid fossil fuels must be achieved, also helping to reduce the temporary natural gas shortage. Efficiency increase in these processes is vital to Venezuelan economy as it could increase the available quantity of petroleum for exports / Mestrado / Planejamento de Sistemas Energeticos / Mestre em Planejamento de Sistemas Energéticos
205

A visual training based approach to surface inspection

Niskanen, M. (Matti) 18 June 2003 (has links)
Abstract Training a visual inspection device is not straightforward but suffers from the high variation in material to be inspected. This variation causes major difficulties for a human, and this is directly reflected in classifier training. Many inspection devices utilize rule-based classifiers the building and training of which rely mainly on human expertise. While designing such a classifier, a human tries to find the questions that would provide proper categorization. In training, an operator tunes the classifier parameters, aiming to achieve as good classification accuracy as possible. Such classifiers require lot of time and expertise before they can be fully utilized. Supervised classifiers form another common category. These learn automatically from training material, but rely on labels that a human has set for it. However, these labels tend to be inconsistent and thus reduce the classification accuracy achieved. Furthermore, as class boundaries are learnt from training samples, they cannot in practise be later adjusted if needed. In this thesis, a visual based training method is presented. It avoids the problems related to traditional training methods by combining a classifier and a user interface. The method relies on unsupervised projection and provides an intuitive way to directly set and tune the class boundaries of high-dimensional data. As the method groups the data only by the similarities of its features, it is not affected by erroneous and inconsistent labelling made for training samples. Furthermore, it does not require knowledge of the internal structure of the classifier or iterative parameter tuning, where a combination of parameter values leading to the desired class boundaries are sought. On the contrary, the class boundaries can be set directly, changing the classification parameters. The time need to take such a classifier into use is small and tuning the class boundaries can happen even on-line, if needed. The proposed method is tested with various experiments in this thesis. Different projection methods are evaluated from the point of view of visual based training. The method is further evaluated using a self-organizing map (SOM) as the projection method and wood as the test material. Parameters such as accuracy, map size, and speed are measured and discussed, and overall the method is found to be an advantageous training and classification scheme.
206

Diagnostic des systèmes dynamiques hybrides à modes non linéaires / Diagnosis of hybrid dynamical systems with nonlinear modes

Zouari, Talel 09 October 2013 (has links)
Cette thèse concerne le diagnostic des systèmes à commutations (classe particulière de systèmes dynamiques hybrides) à modes non linéaires. Certains modes correspondent au fonctionnement normal, sans défaut ; d’autres modes représentent le comportement du système en présence de défauts capteurs, actionneurs ou composants internes. Une représentation générale multi-mode/multimodèle est proposée. Chaque mode non linéaire est modélisé sous la forme multimodèle de type Takagi-Sugeno. Cette modélisation permet de représenter un système non linéaire par une agrégation de modèles locaux linéaires. Une fonction de pondération est utilisée pour déterminer la contribution de chaque modèle local linéaire. Une conception robuste de résidus, basée sur des techniques de projection matricielle est proposée. Cette méthode utilise uniquement les données d’entrées/sorties et la connaissance des fonctions de pondération. En premier lieu, la méthode de projection des données permet de détecter et de localiser les défauts affectant les capteurs dans un mode non linéaire. En deuxième lieu, elle permet de détecter les défauts actionneurs ou les défauts internes en détectant les commutations et en reconnaissant, à chaque instant, le mode actif. Des conditions de discernabilité entre les modes sont établies et un indice de discernabilité calculé en-ligne est utilisé pour réduire la complexité de la méthode d’identification du mode courant. Des exemples académiques sont traités tout au long de la thèse afin d'illustrer en simulation, les différentes méthodes proposées. / This thesis deals with the diagnosis of switching systems (a special class of hybrid dynamical systems) with nonlinear modes. Some modes correspond to the normal operation, i.e. the fault-free case. The other modes may represent the system behavior in the presence of sensors, actuators or internal component faults. A general representation called multimode/multimodels is proposed. It models each nonlinear mode by a set of linear models. A weighting function is used to determine the contribution of each local model. A design method of robust residuals based on projection techniques is proposed. It uses only inputs/outputs data and the weighting functions. The knowledge of local parameters is not needed to compute the residuals. The fault detection and isolation with the data projection method includes firstly, the sensor faults in a nonlinear mode and secondly, the actuator faults or internal faults by detecting the mode switching and by recognizing, at each time-instant, the active mode.Discernability conditions between modes are established and a discernability index computed online is introduced in order to reduce the complexity of the current mode identification method. Academic examples are taken all along the thesis in order to illustrate the effectiveness of the different proposed methods and tools.
207

Null Synthesis and Implementation of Cylindrical Microstrip Patch Arrays

Niemand, Philip 16 May 2005 (has links)
As the wireless communications networks expand, the number of both unwanted directional interferences and strong nearby sources increase, which degrade system performance. The signal-tointerference ratio (SIR) can be improved by using multiple nulls in the directions of the interferences while maintaining omnidirectional coverage in the direction of the network users. For the communication system considered, the interferences are static and their spatial positions are known. A non-adaptive antenna array is needed to provide spatial filtering in a static wireless environment. Omnidirectional arrays, such as cylindrical arrays, are the most suitable to provide the omnidirectional coverage and are capable of suppressing interferences when nulls are inserted in the radiation pattern. In this thesis, a cylindrical microstrip patch antenna array is investigated as an antenna to provide an omnidirectional radiation pattern with nulls at specified angular locations to suppress interference from directional sources. Three null synthesis methods are described and used to provide the omnidirectional array pattern with nulls using the radiation characteristics of the cylindrical microstrip patch antenna elements. The orthogonal projection method is extended to incorporate the directive radiation patterns of the cylindrical microstrip patch elements. Using this method, an optimal pattern that minimises the squared pattern error with respect to the ideal pattern is obtained. Instead of only minimising the array pattern error, a multi-objective optimisation approach is also followed. The objective weighting method is applied in null pattern synthesis to improve the amplitude pattern characteristics of the cylindrical patch arrays. As a third null synthesis technique, a constraint optimisation method is applied to obtain a constrained pattern with the desired amplitude pattern characteristics. The influence of the array attributes on the characteristics of the amplitude patterns obtained from the null synthesis methods, is also studied. In addition, the implementation of the cylindrical microstrip patch array is investigated. The influence of the mutual coupling on the characteristics of the null patterns of the cylindrical patch arrays is investigated utilising simulations and measurements. A mutual coupling compensation technique is used to provide matched and equal driving impedances for all the patch antenna elements given a required set of excitations. Test cases in which this technique is used, are discussed and the consequent improvements in the bandwidth and reflection coefficient of a linear patch arrays are shown. The characteristics of the resulting null pattern for the cylindrical microstrip patch array is also improved using the compensation technique. / Thesis (PhD (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted
208

Les applications qui commutent avec la transformation de Aluthge / Commuting maps with the Aluthge transform

Chabbabi, Fadil 07 July 2017 (has links)
Cette thèse se situe dans le cadre de l'analyse fonctionnelle et plus précisément dans le domaine de la théorie des opérateurs dans des espaces de Hilbert. Elle consiste à étudier les applications bijectives entre des algèbres d'opérateurs, qui commutent avec la transformation de Aluthge. Dans la première partie, nous allons étudier la transformation de Aluthge, qui joue un rôle important en théorie des opérateurs. Nous allons démontrer plusieurs résultats intéressants sur cette transformation. Ces résultats seront utilisés dans la suite de ce travail. Dans la deuxième partie, nous étudierons les bijections additives qui commutent avec la transformation de Aluthge. Nous donnerons également une forme complète des applications ω-additive qui commutent avec cette transformation. Ensuite, nous considérons les applications qui commutent avec la transformation de Aluthge sous le produit usuel et le produit de Jordan. Nous démontrerons que ces applications ont une forme simple. Dans la dernière partie, nous donnerons plusieurs expressions du rayon spectral via la transformation λ-Aluthge et ses itérées. / Our aim in this thesis in function analysis is to study the bijective maps between the algebras of linear and bounded operators, which commute with the Aluthge transform in different way. In the first part, we study the Aluthge transformation which play an crucial role on operator theory in the recent years. We will establish some useful results and properties of the λ-Aluthge transform. These results are required to prove our main theorems in the next chapters. In the second part, we study the bijective and additive maps which commute with the λ-Aluthge transform. We also give a description of ω-additive commuting maps with this transformation. In the last part, we consider the problem of commuting maps with the λ-Aluthge transform, under the usual product and Jordan product, we show that these maps are a simple form. Finally, we give several expressions of the spectral radius via the λ-Aluthge transform and its iterates.
209

Comparison of filtered back projection and Osem in reducing bladder artifacts in pelvic spect imaging

Katua, Agatha Mary 08 July 2011 (has links)
Bladder artifacts during bone single photon emission computed tomography (SPECT) is a common source of errors. The extent and severity of bladder artifacts have been described for filtered back projection (FBP) reconstruction. OSEM may help to address this poor record of bladder artifacts, which render up to 20% of the images unreadable. Aims and objectives To evaluate the relationship of the bladder to acetabulum ratio in guiding the choice of the number of iterations and subsets used for OSEM reconstruction, for reducing bladder artifacts found on FBP reconstruction. Materials and Methods 105 patients with various indications for bone scans were selected and planar and SPECT images were acquired. The SPECT images were reconstructed with both filtered back projection and OSEM using four different combinations of iterations and subsets. The images were given to three well experienced Nuclear Physicians who were blinded to the diagnosis and type of reconstruction used. They then labelled images from the best to the worst after which the data was analysed. The bladder to acetabulum ratio for each image was determined which was then correlated with the different iterations and subsets used. Results The study demonstrated that reconstruction using OSEM led to better lesion detectability compared to filtered back projection in 87.62% of cases. It further demonstrated that the iterations and subsets used for reconstruction of an image correlates to the bladder to acetabulum ratio. Four iterations and 8 subsets yielded the best results in 48.5% of the images whilst two iterations and 8 subsets yielded the best results in 33.8%. The number of reconstructed images which yielded the best results with 2 iterations and 8 subsets were the same as or more than those with 4 iterations and 8 subsets when the bladder/acetabulum ratio was between 0.2-0.39. A ratio below 0.2 or above 0.39 supports the usage of 4 iterations and 8 subsets over 2 iterations and 8 subsets. Conclusion Bladder to acetabulum ratio can be used to select the optimum number of iterations and subsets for reconstruction of bone SPECT for accurate characterization of lesions. This study also confirms that reconstruction with OSEM (vs FBP) leads to better lesion detectability and characterisation. / Dissertation (MSc)--University of Pretoria, 2011. / Nuclear Medicine / unrestricted
210

A play technique programme for autistic children in middle childhood

Davies, Catherine Elizabeth 06 August 2008 (has links)
In this study an attempt was firstly made to theoretically conceptualize autism as a phenomenon in Middle Childhood and the impact thereof on the family, as well as play techniques in the context of autism. The characteristics, behaviour and statistics of autism were looked at as well as the expectations of development of a child (with autism) in middle childhood. The impact of the diagnosis of autism, particularly on the family, was also discussed as well as play techniques in the context of autism. Secondly the researcher focused on exploring the nature of existing play technique programmes on a national and international level. The focus then was placed on developing a play technique programme for autistic children in middle childhood (between the ages of six and 12 years). This programme was then implemented with 12 autistic children in middle childhood at The Key School for Specialized Education in Parktown West, Johannesburg. Each of the 12 respondents were seen for six sessions, with each session lasting 30 minutes. The empirical results were then given through evaluating the play technique programme to assess the effectiveness of the play technique programme. Finally the researcher came to conclusions and recommendations, based on the research findings, regarding the effectiveness of the play technique programme for autistic children in order to enhance the impact of the play technique programme. The broad aim of the study was to develop and evaluate the effectiveness of a play technique programme to enhance the social behaviour of autistic children between the ages of six and 12. The following hypothesis was developed: if autistic children are involved in the play technique programme, then their social behaviour will improve. Consequently, the following sub hypotheses were developed: (1) If autistic children are involved in the play technique programme then their verbal communication skills will improve; (2) If autistic children are involved in a play technique programme then their non-verbal communication skills will improve; (3) If autistic children are involved in a play technique programme then their social interaction skills will improve; (4) If autistic children are involved in a play technique programme then their challenging behaviours will decrease. In the context of applied research, intervention research was the most appropriate type of research for this particular study. This is due to the fact that the researcher aimed to conduct an intervention, namely a play technique programme, which was attempting to impact a particular problem within society, namely the lack of support provided for parents and/or professionals dealing with autistic children in middle childhood. The research approach used in the study was quantitative. The researcher utilized the one-group pretest-posttest design (i.e. quasi-experimental/associative design). In this particular design there is a measurement (pre-test) of a dependent variable (the autistic children’s social behaviour) when no independent variable (play technique programme) is present. Subsequently the independent variable is introduced, followed by a repeated measurement (posttest) of the dependent variable. The 12 respondents were selected through probability sampling, more specifically stratified and systematic sampling. A self-constructed measuring instrument was used, within structured observation, to evaluate the respondents’ changes in social behaviour, due to exposure to the various play techniques. The specific behaviours focused on included verbal communication, non-verbal communication, social interaction and challenging behaviours. The findings confirmed that the play technique programme had a highly significant effect on all four areas measured (verbal communication, non-verbal communication, social interaction and challenging behaviour). The respondents (the autistic children) therefore showed a marked improvement in their social behaviour due to being involved in the play technique programme and the conclusion that can be reached is that the play technique programme can be perceived as having had the impact that was hoped for. / Thesis (PhD)--University of Pretoria, 2008. / Social Work and Criminology / unrestricted

Page generated in 0.0202 seconds