The implementation of learning styles models in the classroom remains a heavily debated topic in education. Notable problems with utilization of learning styles in the classroom include a lack of empirical research support and potential maladaptive effects on student learning and motivation. The primary research questions focused on the presence and quantity of learning styles discussion in the text, which definitions, models, and recommendations were presented, and which of the cited references were based on empirical data. The answers to these questions were compared between educational psychology and introduction to education textbooks. A content analysis of introduction to education (n = 10) and educational psychology (n = 10) textbooks was conducted. Eighty percent of the textbooks included a discussion of learning styles. Half of the textbooks defined learning style as a preference or approach and the other half as an individual process or style. One-fourth of the textbooks recommended matching instructional methods to learning styles. One comparison of text types, the number of empirical references cited in the text, was statistically significant. Given that most textbooks do not recommend matching instructional methods to learning styles, future research should examine the source of teachers’ beliefs that student learning is improved with the matching of learning styles to teaching approach.

A new integrated layout optimization method is proposed here for the design of multi-component systems. By introducing movable components into the design domain, the components layout and the supporting structural topology are optimized simultaneously. The developed design procedure mainly consists of three parts: (i). Introduction of non-overlap constraints between components. The Finite Circle Method (FCM) is used to avoid the components overlaps and also overlaps between components and the design domain boundaries. It proceeds by approximating geometries of components and the design domain with numbers of circles. The distance constraints between the circles of different components are then imposed as non-overlap constraints. (ii). Layout optimization of the components and supporting structure. Locations and orientations of the components are assumed as geometrical design variables for the optimal placement. Topology design variables of the supporting structure are defined by the density points. Meanwhile, embedded meshing techniques are developed to take into account the finite element mesh change caused by the component movements. Moreover, to account for the complicated requirements from aerospace structural system designs, design-dependent loads related to the inertial load or the structural self-weight and the design constraint related to the system gravity center position are taken into account in the problem formulation. (iii). Consistent material interpolation scheme between element stiffness and inertial load. The common SIMP material interpolation model is improved to avoid the singularity of localized deformation due to the presence of design dependent loading when the element stiffness and the involved inertial load are weakened with the element material removal. Finally, to validate the proposed design procedure, a variety of multi-component system layout design problems are tested and solved on account of inertia loads and gravity center position constraint.

To extend the use of computational techniques like finite element analysis to clinical settings, it would be beneficial to have the ability to generate a unique model for every subject quickly and efficiently. To this end, we previously developed two mapped meshing tools that utilized force and displacement control to map a template mesh to a subject-specific surface. This work is an extension of those methods; the objective of this study was to map a template block structure, common to multi-block meshing techniques, to a subject-specific surface. The rationale was that the blocks are considerably less refined and may be readily edited, thereby yielding a mesh of high quality in less time than mapping the mesh itself. In this paper, the versatility and robustness of the method was verified by processing four datasets. The method was found to be robust enough to cope with the variability of bony surface size, spatial position and geometry, producing building block structures that generated meshes comparable to those produced using building block structures that were created manually.

This thesis discusses the application, evaluation, and extension of dimensionally adaptive meshing to the numerical solution of velocity and pressure fields inside cylindrical reactors. Due to the high length to diameter ratios of many cylindrical reactor vessels the flow field can become axisymmetric, allowing for simplification of the governing equations and significant reduction in computational time required for solution. A fully 3D solver is developed from existing computational tools at BYU and validated against theoretical velocity profiles for pipe flow at various Reynolds numbers, as well as with experimental data for an axial-fired center jet with recirculating flow. Dimensionally adaptive meshing is then incorporated into the validated 3D solver. The boundary conditions and assumptions at the dimensional boundary are discussed. The flow information is passed across the boundary through spatial mass-weighted averaging. The 3D and axisymmetric computational domains are decoupled from one another so information can only be passed from the 3D domain downstream to the axisymmetric domain. The dimensional boundary placement must meet two main requirements, the flow must be one-way and axisymmetric. It is found that the flow becomes axisymmetric early on in the reactor (~0.3-0.4 m), but recirculation exists farther downstream (until ~0.61 m) and thus governs the placement of the dimensional boundary. The resulting computational tool capable of running simulations using dimensionally adaptive meshes is called CEDAR (Computationally Efficient Dimensionally Adaptive Recirculating flow solver). Several studies are then undertaken to examine CEDAR's ability to reproduce exit velocity profiles comparable to those produced by a fully 3D mesh, including variations in pressure, firing rate, and geometry. It is found that the flow structure inside the reactor is self-similar over a wide range of operating parameters as long as the burner jets are turbulent. This observation is supported by free and confined jet theory. These theories also provide a method for placing the dimensional boundary, which is a linear function of the confining geometry diameter only (assuming that the jet diameter is less than 1/10 the diameter of the confining geometry). All exit velocity profiles produced by CEDAR are on average within 5% of the fully 3D profiles. Timing studies reveal an average 5.16 times speedup in computational time over fully 3D computations.

The presented research summarizes (1) the development of a rapid prototyping framework, (2) the application of advance meshing algorithms, data structures, programming languages and libraries toward the field of numerical surface-water modeling (NSWM), (3) the application of (2) in (1), and (4) a real world application. The result of the research was the development of a prototype grid generator tool, the Mesh Generation and Refinement Tool (MGRT). MGRT supports a customizable interface and plug-and-play functionality through the use of plug-ins and incorporates a plug-in based topology/geometry system. A detailed explanation of the data structures, algorithms, and tools used to construct the MGRT are presented. Additionally, the construction of a mesh of Mobile Bay is presented. This represents a real world application of the MGRT. This tool provides many benefits over current tools in NSWM, which include faster meshing and the ability the use any grid generator that can be plugged-in.

A Positive Engagement, Continuously Variable Transmission (PECVT) allows for a continuously variable transmission ratio over a given range using positively engaged members, such as gear teeth, to transmit torque. This research is an investigation of PECVTs to establish a classification system and governing principles that must be satisfied for an embodiment to overcome the non-integer tooth problem. Results of an external patent search are given as examples of different concepts and PECVT embodiments that have been employed to negate the effects of the non-integer tooth problem. To classify all published and unpublished PECVT embodiments, a classification system is developed, based on how particular PECVT embodiments overcome the non-integer tooth problem. Two classes of PECVTs are defined: 1) the problem correction class and 2) the alternate device class. General principles that must be satisfied for a promising PECVT embodiment to exist in each class of PECVTs are also developed. These principles, along with the classification system, are the major contribution of this research. The principles describe what an embodiment in each of the PECVT classes must accomplish to negate the effects of the non-integer tooth problem. A product development phase integrated with TRIZ methodology is implemented to generate several concepts that satisfy the newly developed general principles and the product specifications that were also created. A screening and scoring process is used to eliminate less promising concepts and to find the most viable PECVT embodiment. An embodiment that only operates at preferred transmission ratios, where no meshing problems exist, proves to be the most promising concept based on the results of this methodology. The embodiment also utilizes cams and a differential device to provide the needed correction to the orientation of the driving members when misalignment occurs. This misalignment only occurs while transitioning between preferred operating ratios. A case study of the final embodiment developed by Vernier Moon Technologies and Brigham Young University is presented and analyzed to show how the final concepts ensure proper engagement without the effects of the non-integer tooth problem. The final embodiment is not the optimal solution but represents a conceptual design of an embodiment that satisfies the governing principles. The classification system and the governing principles that have been established are valid for all PECVT embodiments and will be valuable in future research. Future work yet to be conducted for this research, including an involutometry analysis, is discussed as well as other recommendations.

Simulations were performed to evaluate solution adaptive meshing strategies for flows with vortices whose axes of rotation are parallel to the bulk fluid motion. Two configurations were investigated: a wing in a wind tunnel and a missile spinning at 30Hz and 60Hz at 0◦ angle of attack with canards deflected 15◦. Feature-based descriptors were used to identify regions of the flow near vortices that are candidate regions for adaptive meshing. Several different adaptive meshing techniques were evaluated. These techniques include refinement around the vortex core, refinement near the vortex extent surface, refinement inside the extent surface, refinement inside and near the extent surface, and mesh regeneration using the vortex extent surface as an embedded surface. Results for the wing case, compared to experimental data, indicate that it is necessary to refine the region within and near the vortex extent surface to accurately recreate physical characteristics and achieve an acceptable solution.

No description available.

Yes / Microstrip patch antennas with harmonic suppression are designed and optimised, using a genetic algorithm and applying a novel adaptive meshing program to generate a wire-grid simulation. A coaxially-fed air-dielectric patch antenna design with a folded patch was investigated. It was confirmed that antennas with excellent performances could be designed by this method. / MSCRC

Orientador: Aparecido Carlos Gonçalves / Resumo: Pares engrenados são elementos de transmissão de potência amplamente utilizados em máquinas e equipamentos, todavia as falhas catastróficas desses componentes são comuns e dispendiosas. A análise de vibrações está entre as técnicas de diagnóstico de defeitos incipientes utilizadas em manutenção preditiva, posto que a presença de uma falha altera o comportamento dinâmico do sistema e o estado de degradação pode ser detectado pelo monitoramento dos sinais de vibração. Na indústria atual, onde as aquisições de dados, tanto para controle de processos, quanto para o monitoramento das condições de integridade de equipamentos, são realizadas em tempo real, faz-se necessário o desenvolvimento de métodos que aumentem a confiabilidade das tomadas de decisões em relação à identificação, localização e prognóstico de falhas. O objetivo deste trabalho é desenvolver um modelo matemático de par de engrenagens que auxilie no monitoramento da condição e validar o modelo dinâmico com dados de vibração de um multiplicador de velocidades obtidos experimentalmente. Para tanto, foi elaborada uma metodologia baseada no modelo dinâmico de par engrenado com 6 graus de liberdade para simulação de sinais de vibração; nesse modelo, inclui-se erros geométricos no perfil do dente; de maneira analítica, simula-se uma a trinca do dente de uma das engrenagens que ocasiona a queda de rigidez em função do tempo; desenvolveu-se também um experimento com um multiplicador de velocidades; e, por fim, algumas técnic... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Spur gears are transmission power elements widely used in machinery, however catastrophic failures of this components are just as common and onerous. Vibration analysis is a technique, in among of others, that can be used in diagnostics of incipient damages, common in predictive maintenance, because they change the dynamic behavior of the mechanical system, and the degradation state can be detected by vibration signal or noise. In the current industry production, in which real-time data acquisition - whether for processes control, or for health condition monitoring of equipment - is the reality, it is necessary to develop auxiliary methods that provide high reliability to identification, localization and failure prognostics. In this work, the main objective is to provide a spur gears’ model-based methodology for condition-monitoring and to validate a dynamic model with experimental vibration data of a gearbox. Hence, a dynamic model of spur meshing gears was developed considering a 6 degrees of freedom and time-varying meshing stiffness to simulate vibrations signals; a tooth profile error was also included; in this analytical model, a straight crack was simulated by reducing the meshing stiffness in a tooth; experiments with a gearbox experimental set were run; and, some signal processing was apllied in the vibration data. The results allowed the model validation with the comparison between simulate and experimental signals, in time-domain and frequency-domain / Mestre