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This study aims to identify and explain relationships between some major factors associated with successful reading at Grade 5 level in South African primary schools. In South Africa, grave concerns with regards to low levels of student achievement pervade research initiatives and educational debates. Despite considerable investments in educational inputs (such as policy and resources) and processes (such as curriculum provision and teacher support), outcomes (such as student achievement) remain disappointingly low. The South African population is characterized by great diversity and variation. With 11 official languages, current educational policy in South Africa advocates an additive bilingualism model and students in Grade 1 to 3 are taught in their mother tongue. Thereafter, when these students progress to Grade 4, the language of learning and teaching changes to a second language, which in most cases is English. At this key developmental stage students are also expected to advance from learning to read to a stage where they can use reading in order to learn. With this complexity of issues in mind, Hierarchical Linear Modeling (HLM) was used to determine the effect of a number of explanatory variables at learner and school level on reading achievement as outcome variable, while controlling for language using the South African Progress in International Reading Literacy Study (PIRLS) 2006 data. As an international comparative evaluation of reading literacy involving more than 40 countries, PIRLS 2006 was the second, after PIRLS 2001, in a series of planned five-year cycles of assessment to measure trends in children’s reading literacy achievement, policy and practices related to literacy. Grade 5 learners in South African primary schools who participated in PIRLS 2006 were not able to achieve satisfactory levels of reading competence. The gravity of this finding is exacerbated by the fact that these learners were tested in the language in which they had been receiving instruction during the Foundation Phase of schooling. This study found most significant factors associated with reading literacy at learner-level, but this does not mean that the existence of teacher- and school-level factors is not of importance. While some explanatory factors at learner-level can more easily become the target of reading interventions, the higher level effect of the classroom and school are not diminished by this study. Creemers’ Comprehensive Model of Educational Effectiveness was utilized as theoretical point of departure. Creemers’ model was adapted for the purposes of this study to reflect a South African model of reading effectiveness in contrast with Creemers’ original use of it as a model of school effectiveness. Evidence was provided that the conceptual framework was inadequate in identifying factors affecting reading achievement for all South African language groupings. More specifically, the adapted South African reading effectiveness model was only appropriate in explaining reading achievement scores for the Afrikaans and English language groupings than for those from African language groupings. / Thesis (PhD)--University of Pretoria, 2010. / Science, Mathematics and Technology Education / unrestricted

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O dilema do prisioneiro é geralmente visto como o ponto de partida para entender o problema da cooperação. Em comparação com o dilema do prisioneiro discreto e iterado, poucos estudos existem sobre o dilema do prisioneiro contínuo e iterado. A maioria dos trabalhos que investigaram o dilema do prisioneiro contínuo e iterado concentrou-se no período de 1990 a 2000, não obtendo resultados conclusivos sobre a melhor estratégia a ser adotada neste tipo de jogo. Duas estratégias diferentes se destacam neste tipo de dilema. A primeira é a estratégia RTS (Raise-the-Stakes) de Roberts e Sherrat (1998) que testa o terreno antes de aumentar os investimentos na relação. A segunda deriva do modelo LRS (Linear Reactive Strategies) de Wahl e Nowak (1999a). Esta última estratégia estando em equilíbrio de Nash cooperativo apresenta três características: (i) generosidade, i.e., investir o máximo possível no início da relação de cooperação; (ii) otimismo, i.e., contar com o melhor cenário para as próximas rodadas, e (iii) intransigência. Esta pesquisa tem como objetivo principal contrapor as estratégias RTS e LRS num dilema do prisioneiro contínuo e iterado, na presença e ausência de ruído, com jogadas simultâneas e alternadas e para diferentes valores do parâmetro w (probabilidade de interagir novamente). Restringimos a nossa análise a um conjunto de seis estratégias: ALLC, ALLD, TFT, RTS, LRS e RTSM. O método utilizado foi o da simulação baseada em agente (ABM) no formato de torneios, semelhante ao de Axelrod (2006), Roberts & Sherratt (1998), Nowak & Sigmund (1992) e Nowak & Sigmund (1993). Utilizamos o software Netlogo e documentamos todo o processo da concepção e construção do modelo por meio da ferramenta TRACE (TRAnsparent and Comprehensive model Evaludation). Os resultados mostram que as estratégias mais cooperativas são mais favorecidas quando o jogo consiste em jogadas alternadas ao invés de simultâneas. A estratégia RTS teve melhor desempenho em jogos simultâneos para valores intermediários de w, na presença ou ausência de ruído. Por sua vez, a estratégia LRS teve melhor desempenho nos jogos simultâneos, na presença ou ausência de ruído, ou alternados e na presença de ruído, em ambos os casos para valores grandes de w / The prisoner\'s dilemma is generally seen as the starting point for understanding the problem of cooperation. In comparison with the discreet and iterated prisoner\'s dilemma, few studies exist on the continuous iterated prisoner\'s dilemma. Most of the works that have investigated the continuous iterated prisoner\'s dilemma has concentrated in the period from 1990 to 2000, not getting conclusive results on the best strategy to be adopted in this type of game. Two different strategies stand out in this kind of dilemma. The first is the RTS strategy (Raise-the-Stakes) of Roberts and Sherrat (1998) that tests the ground before increasing investment in the relationship. The second is the model deriva LRS (Linear Reactive Strategies) de Wahl and Nowak (1999a). This last strategy being in Nash equilibrium cooperative presents three characteristics: (i) generosity, i.e., investing as much as possible at the beginning of the cooperation relationship; (ii) optimism, i.e., rely on the best scenario for the next rounds, and (iii) intransigence. This research has as main goal to reconcile opposing RTS strategies and LRS in a continuous iterated prisoner\'s dilemma, in the presence and absence of noise, with simultaneous moves and alternate and for different values of the parameter w (probability of interacting again). We restrict our analysis to a set of six strategies: ALLC, ALLD, TFT, RTS, LRS and RTSM (halfway between RTS and LRS). The method used was the agent-based simulation (ABM) in tournament format, similar to that of Axelrod (2006), Roberts (1998), Sherratt & Nowak & Sigmund (1992) and Nowak & Sigmund (1993). We use the NetLogo software and document the whole process of design and construction of the tool model TRACE (TRAnsparent and Comprehensive model Evaludation). The results show that most strategies are more favoured unions when the game consists of alternating plays rather than simultaneous. The RTS strategy had better performance in simultaneous games for intermediate values of w, in the presence or absence of noise. In turn, the IRS strategy had better performance when simultaneous games, in the presence or absence of noise, or switched, and in the presence of noise, in both cases, for large values of w

O dilema do prisioneiro é geralmente visto como o ponto de partida para entender o problema da cooperação. Em comparação com o dilema do prisioneiro discreto e iterado, poucos estudos existem sobre o dilema do prisioneiro contínuo e iterado. A maioria dos trabalhos que investigaram o dilema do prisioneiro contínuo e iterado concentrou-se no período de 1990 a 2000, não obtendo resultados conclusivos sobre a melhor estratégia a ser adotada neste tipo de jogo. Duas estratégias diferentes se destacam neste tipo de dilema. A primeira é a estratégia RTS (Raise-the-Stakes) de Roberts e Sherrat (1998) que testa o terreno antes de aumentar os investimentos na relação. A segunda deriva do modelo LRS (Linear Reactive Strategies) de Wahl e Nowak (1999a). Esta última estratégia estando em equilíbrio de Nash cooperativo apresenta três características: (i) generosidade, i.e., investir o máximo possível no início da relação de cooperação; (ii) otimismo, i.e., contar com o melhor cenário para as próximas rodadas, e (iii) intransigência. Esta pesquisa tem como objetivo principal contrapor as estratégias RTS e LRS num dilema do prisioneiro contínuo e iterado, na presença e ausência de ruído, com jogadas simultâneas e alternadas e para diferentes valores do parâmetro w (probabilidade de interagir novamente). Restringimos a nossa análise a um conjunto de seis estratégias: ALLC, ALLD, TFT, RTS, LRS e RTSM. O método utilizado foi o da simulação baseada em agente (ABM) no formato de torneios, semelhante ao de Axelrod (2006), Roberts & Sherratt (1998), Nowak & Sigmund (1992) e Nowak & Sigmund (1993). Utilizamos o software Netlogo e documentamos todo o processo da concepção e construção do modelo por meio da ferramenta TRACE (TRAnsparent and Comprehensive model Evaludation). Os resultados mostram que as estratégias mais cooperativas são mais favorecidas quando o jogo consiste em jogadas alternadas ao invés de simultâneas. A estratégia RTS teve melhor desempenho em jogos simultâneos para valores intermediários de w, na presença ou ausência de ruído. Por sua vez, a estratégia LRS teve melhor desempenho nos jogos simultâneos, na presença ou ausência de ruído, ou alternados e na presença de ruído, em ambos os casos para valores grandes de w / The prisoner\'s dilemma is generally seen as the starting point for understanding the problem of cooperation. In comparison with the discreet and iterated prisoner\'s dilemma, few studies exist on the continuous iterated prisoner\'s dilemma. Most of the works that have investigated the continuous iterated prisoner\'s dilemma has concentrated in the period from 1990 to 2000, not getting conclusive results on the best strategy to be adopted in this type of game. Two different strategies stand out in this kind of dilemma. The first is the RTS strategy (Raise-the-Stakes) of Roberts and Sherrat (1998) that tests the ground before increasing investment in the relationship. The second is the model deriva LRS (Linear Reactive Strategies) de Wahl and Nowak (1999a). This last strategy being in Nash equilibrium cooperative presents three characteristics: (i) generosity, i.e., investing as much as possible at the beginning of the cooperation relationship; (ii) optimism, i.e., rely on the best scenario for the next rounds, and (iii) intransigence. This research has as main goal to reconcile opposing RTS strategies and LRS in a continuous iterated prisoner\'s dilemma, in the presence and absence of noise, with simultaneous moves and alternate and for different values of the parameter w (probability of interacting again). We restrict our analysis to a set of six strategies: ALLC, ALLD, TFT, RTS, LRS and RTSM (halfway between RTS and LRS). The method used was the agent-based simulation (ABM) in tournament format, similar to that of Axelrod (2006), Roberts (1998), Sherratt & Nowak & Sigmund (1992) and Nowak & Sigmund (1993). We use the NetLogo software and document the whole process of design and construction of the tool model TRACE (TRAnsparent and Comprehensive model Evaludation). The results show that most strategies are more favoured unions when the game consists of alternating plays rather than simultaneous. The RTS strategy had better performance in simultaneous games for intermediate values of w, in the presence or absence of noise. In turn, the IRS strategy had better performance when simultaneous games, in the presence or absence of noise, or switched, and in the presence of noise, in both cases, for large values of w

Master thesis is devoted to the development of a model of socially responsible lending with LLC "Home Credit Bank". Within this goal, the paper examines the essence and principles of responsible lending; analysis of current concepts and problems in Russian and foreign practice. / Магистерская диссертация посвящена вопросам разработки модели социально- ответственного кредитования в ООО «Home Credit Bank». В рамках поставленной цели в работе поставлены задачи изучения сущности и принципов ответственного кредитования; анализа современных концепций и проблем в российской и зарубежной практике.

Tesis por compendio / [ES] El ruido de rodadura de vehículos ferroviarios presenta importantes desafíos en entornos urbanos y suburbanos, siendo precisa una comprensión integral de sus mecanismos subyacentes para una mitigación efectiva. Esta Tesis ofrece una investigación exhaustiva sobre la generación de ruido de rodadura, tanto en vías rectas como curvas, a través del desarrollo de modelos avanzados de alta frecuencia y herramientas de cálculo para una rigurosa predicción de niveles de ruido. El ruido de rodadura surge de la interacción entre las ruedas y los carriles en presencia de imperfecciones en sus superficies de contacto. Los principales componentes ferroviarios que contribuyen a la emisión acústica son las traviesas, los carriles y las ruedas. Las traviesas y los carriles están conectados por medio de las placas de asiento, mientras que las ruedas y los carriles están dinámicamente acoplados a través de su contacto. En consecuencia, cambios en cualquier componente pueden afectar al comportamiento dinámico y acústico del resto, subrayando la necesidad de un modelo integral para abordar eficazmente la radiación por ruido de rodadura. En esta Tesis se exploran y desarrollan diferentes modelos dinámicos de la vía y del eje montado. La vía, que se asume infinita, se describe utilizando la teoría de estructuras periódicas y se caracteriza por sus números y formas de onda. El eje montado se modeliza mediante el Método de Elementos Finitos y se caracteriza por sus frecuencias naturales y modos de vibración. La interacción rueda/carril se describe como una relación linealizada entre el movimiento relativo de ambos componentes y las fuerzas de contacto. Cabe indicar que los modelos explorados en este trabajo están formulados en el dominio de la frecuencia. Asimismo, se realiza un estudio de influencia del diseño de la vía en la radiación por ruido de rodadura, cuantificando los parámetros contribuyentes a la emisión acústica mediante técnicas estadísticas. Los resultados apuntan a que la geometría del carril tiene un impacto limitado en la radiación, mientras que las propiedades viscoelásticas de la vía, en particular la rigidez de la placa de asiento, desempeñan un papel fundamental en la generación de ruido. Es remarcable que, entre los distintos diseños, se han encontrado variaciones de hasta 7,4 dB(A) en la radiación acústica. Durante el desarrollo de esta investigación, se ha prestado atención al modelizado del eje montado. Su rotación se incluye usando coordenadas Eulerianas, lo que resulta un enfoque conveniente ya que el punto de contacto de la rueda con el carril permanece en una posición espacial constante. Dada la simetría axial de su geometría, la respuesta dinámica del eje montado se expande a lo largo de la dirección circunferencial mediante series de Fourier, lo que permite formular el comportamiento dinámico y acústico de este cuerpo tridimensional (3D) en un marco bidimensional (2D), resolviendo analíticamente la coordenada circunferencial. Esta metodología ofrece sin pérdida de generalidad una reducción del tiempo de cálculo computacional, lo que hace que el modelo sea idóneo para su integración en algoritmos de optimización. Por último, se realiza una investigación pionera sobre el ruido de rodadura cuando el vehículo negocia una curva. Si bien la curva está generalmente asociada con el ruido por chirridos, esta Tesis explora y confirma la importancia que también tiene el ruido de rodadura en estas condiciones. Para ello, se modelizan los efectos inerciales y giroscópicos que sufre un eje montado al describir una trayectoria curva. Además, diferentes fenómenos complejos que ocurren en el contacto rueda/carril, como por ejemplo el movimiento relativo entre estos elementos, se incorporan en el modelo de interacción. Los resultados indican que la posición del contacto rueda/carril sirve como un buen indicador del impacto que la negociación de una curva tiene en el ruido de rodadura. / [CA] El soroll de rodament de vehicles ferroviaris presenta importants reptes en entorns urbans i suburbans, requerint una comprensió integral dels seus mecanismes subjacents per a una mitigació efectiva. Aquesta Tesi ofereix una investigació exhaustiva sobre la generació de soroll de rodament, tant en vies rectes com corbes, mitjançant el desenvolupament de models avançats d'alta freqüència i eines de càlcul per a la rigorosa predicció dels nivells de soroll radiat. El soroll de rodament sorgeix de la interacció entre les rodes i els carrils en presència d'imperfeccions en les seues superfícies de contacte. Els principals components ferroviaris que contribueixen a l'emissió acústica són les travesses, els carrils i les rodes. Les travesses i els carrils estan connectats a través de les plaques d'assentament, mentre que les rodes i els carrils estan acoblats mitjançant la seua interacció. En conseqüència, canvis en qualsevol component poden afectar al comportament dinàmic i acústic de la resta, subratllant la necessitat d'un model integral. En aquesta Tesi s'exploren i desenvolupen diversos models dinàmics de la via i de l'eix muntat. La via, que es considera infinita, es descriu utilitzant la teoria d'estructures periòdiques i es caracteritza pels seus números i formes d'ona. L'eix muntat es modelitza mitjançant el Mètode d'Elements Finits i es caracteritza per les seues freqüències naturals i modes de vibració. La interacció entre l'eix muntat i la via es descriu com una relació linealitzada entre el moviment relatiu d'ambdós components i les forces de contacte. Cal assenyalar que els models explorats en aquest treball estan formulats en el domini de la freqüència. Així mateix, es realitza un estudi d'influència del disseny de la via en la radiació, quantificant els paràmetres contribuents a l'emissió acústica mitjançant tècniques estadístiques. Els resultats apunten que la geometria del carril té un impacte limitat en la radiació sonora, mentre que les propietats viscoelàstiques de la via, en particular la rigidesa de la placa d'assentament, tenen un paper fonamental en la generació de soroll. És destacable que, entre els diferents dissenys, s'han trobat variacions de fins a 7,4 dB(A) en la radiació per soroll de rodament. Durant el desenvolupament d'aquesta investigació, s'ha prestat atenció al modelatge de l'eix muntat. La seua rotació s'inclou en la formulació utilitzant coordenades Eulerianes, la qual cosa resulta un enfocament convenient ja que el punt de contacte de la roda amb el carril roman en una posició constant. Donada la simetria axial de la seua geometria, la resposta dinàmica de l'eix muntat s'amplia al llarg de la direcció circumferencial mitjançant sèries de Fourier, permetent formular el comportament dinàmic i acústic d'aquest cos tridimensional (3D) en un marc bidimensional (2D), i resolent la coordenada circumferencial analíticament. Aquesta metodologia ofereix sense pèrdua de generalitat una reducció del temps de càlcul computacional, la qual cosa fa que el model siga idoni per a la seua integració en algoritmes d'optimització. Finalment, es realitza una investigació pionera sobre el soroll de rodament quan el vehicle negocia una corba. Si bé la corba està generalment associada amb el soroll per grinyols, aquesta Tesi explora i confirma la importància que també té el soroll de rodament en aquestes condicions. Per a això, es modelitzen els efectes inercials i giroscòpics que pateix un eix muntat al descriure una trajectòria corba. A més, diferents fenòmens complexes que ocorren en el contacte roda/carril, com el moviment relatiu entre aquests elements, s'incorporen en el model d'interacció. Els resultats indiquen que la posició del contacte roda/carril serveix com un bon indicador de l'impacte que la negociació d'una corba té en el soroll de rodament. / [EN] Rolling noise emission in railway systems presents significant challenges in urban and suburban environments, requiring a comprehensive understanding of its underlying mechanisms for effective mitigation. This Thesis offers a thorough investigation into rolling noise generation, considering both tangent and curved tracks, through the development of advanced high-frequency models and calculation tools to predict noise levels accurately. Rolling noise arises from the interaction between railway wheels and tracks in the presence of roughness on their contact surfaces. The principal components contributing to the acoustic emission are the sleepers, rails, and wheels. Sleepers and rails are interconnected through rail pads, while wheels and rails are dynamically coupled due to their contact. Consequently, changes in any component might impact the dynamic and acoustic behaviour of all of them, outlining the necessity of a comprehensive model to address rolling noise radiation effectively. Various models for the track and wheelset are explored and developed in this Thesis. The track, assumed to be infinite, is described using periodic structure theory and it is characterised by its wavenumbers and waveshapes. The wheelset is modelled through the Finite Element Method (FEM) and it is characterised by its natural frequencies and vibration modes. The wheelset and track interaction is described as a linearised relationship between the relative motion of both components and the contact forces. The models examined in this work are formulated in the frequency domain. Identified track properties influencing rolling noise radiation are quantified using statistical techniques. While the rail geometry is found to have a limited impact on the total radiation, the viscoelastic properties of the track, particularly the rail pad stiffness, play a crucial role in noise generation. Variations up to 7.4 dB(A) were observed for different track designs. Special attention is devoted to the wheelset modelling in this Thesis. Its rotation is considered using Eulerian coordinates, a convenient approach as the wheel contact point with the rail remains at a constant spatial position. Given the axial symmetry of its geometry, the wheelset dynamic response is expanded around the circumferential direction using Fourier series, which yields a two-dimensional (2D) formulation of the dynamic and acoustic behaviour of this three-dimensional (3D) system, with the circumferential coordinate being solved analytically. This methodology, denoted as axisymmetric approach, offers a significant reduction in the associated computational calculation time while preserving accuracy, making the model well suited for its integration into optimisation algorithms. Lastly, a novel investigation into rolling noise when the vehicle negotiates a curve is conducted. While curved tracks are generally associated with squeal noise, this Thesis offers valuable insights into the importance of rolling noise as well. To achieve this, the inertial and gyroscopic effects associated with a wheelset running on a curve are modelled. Complex phenomena occurring at the wheel/rail contact, such as the relative motion between these two elements, are incorporated into the interaction model. The results indicate that the wheel/rail contact position serves as a reliable indicator of the impact of a curve on the rolling noise. / This Thesis has been supported by Ministerio de Ciencia, Innovación y Universidades in the framework of the FPU grant program. Grants FPU18/03999, EST21/00213, and EST22/00353 as well as projects TRA2017-84701-R, PID2020-112886RA-I00, and PID2023-148483OB-I00 funded by MCIN/AEI/10.13039/501100011033, “ESF Investing in your future”, and “ERDF A way of making Europe” are acknowledged. The author also expresses his gratitude for the support provided by Programa PROMETEO/2021/046 of Generalitat Valenciana. / Andrés Ruiz, VT. (2024). Comprehensive dynamic models of railway wheelsets and tracks for the prediction of rolling noise [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206074 / Compendio