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Thesis (Ph. D.)--Tufts University, 2001. / Adviser: David W. Krumme. Submitted to the Dept. of Computer Science. Includes bibliographical references (leaves 433-435). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Ce travail s'articule en quatre parties. Les trois premières ont pour socle commun l'adaptation d'un schéma volumes finis (VFFC) à des situations variées, dans le but d'un gain en efficacité pour la simulation numérique d'écoulements complexes. La première partie concerne la simulation numérique efficace de la chute d'un bloc de liquide au sein d'une poche de gaz, et propose un nouveau modèle mutualisant de précédents travaux pour associer finesse des résultats et efficacité de calcul. La deuxième partie vise à la mise en place d'un schéma AMR (Adaptive Mesh Refinement) général pour la résolution par volumes finis des systèmes non conservatifs. La troisième partie a pour finalité le couplage dynamique de deux modèles représentant plus ou moins finement une physique donnée. Enfin, dans un tout autre domaine où l'efficacité de résolution des équations aux dérivées partielles revêt également une grande importance, la quatrième partie s'intéresse au problème du flot optique en imagerie - c'est à dire à la recherche d'un champ de déplacement à partir d'une suite d'image - et approfondit une méthode existante (méthode de Horn et Schunck) d'un point de vue pratique et théorique. / This work is divided into four parts. The first three parts, as a common base, aim at adapting a finite volume scheme (VFFC) to various situations, in order to get a better efficiency for the numerical simulation of complex flows. The first part deals with the efficient numerical simulation of a falling block of liquid in a gas pocket, and proposes a new model to combine previous work for associating precision of results and computational efficiency. The second part aims at the establishment of a general AMR (Adaptive Mesh Refinement) scheme for resolution by finite volumes of non-conservative systems. The purpose of the third part is the dynamic coupling of two models representing more or less finely a given physical system. Finally, in any other area where the efficiency of solving partial differential equations is of great importance too, the fourth part deals with the problem of optical flow in imaging - i.e. the research of a displacement field from several successive images - and deepens an existing method (Horn and Schunck method) from a practical and theoretical perspective.

The purpose of this study was to evaluate the impact of computer-based simulation on prelicensure senior second semester undergraduate baccalaureate nursing students' knowledge and satisfaction. The goal was to explore the current state of nursing education in relation to the nursing student's experience with interruptions and interruption management as interruptions and interruption management are an underexplored area of the nursing education experience, yet interruptions impact nursing performance and patient safety. Including effective interruption management in nursing education is the ultimate aim of this effort. The design of the study was a descriptive case study with mixed methods including quantitative and qualitative data collection and analysis. The quantitative analysis encompassed pretest and posttest drug calculation knowledge tests and a satisfaction survey. The qualitative portion of the study involved a focus group discussion relating to the nursing student's experience with interruptions and interruption management. The study results demonstrated that the participants were satisfied with the computer-based simulation. Furthermore, the results demonstrated that the professional nursing education of the study participants was devoid of interruption and interruption management education in the classroom, lab, and high-fidelity simulation. The themes that emerged from this study describe the current state of the second semester nursing student's experience with interruptions and interruption management and inform the need for interruption and interruption management education in professional nursing educational programs.

This study develops a methodology for the analysis of Part Task Trainer (PTT) refresh scheduling used in conjunction with large simulators. A human performance model is defined through the development of descriptive equations and system random variables. PTT scheduling calculations are performed by employing a computer program simulation. The computer algorithm generates a set of random vectors to represent the learning characteristics of a sample group of individual trainees. The relationships between simulator scheduling time, PTT frequency training, and model variables are demonstrated to be user interactive. This will allow the PTT refresh scheduling program to be used as an analytical tool for the investigator and training planner. A computer summary of the resulting simulator retraining times with PTT refresh is provided to the user.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Computer simulations of the optical servo functions of optical disk drives are developed and compared with experimental results. The focus control servo is investigated first, with emphasis on the astigmatic focus detection method. A paraxial ray trace, enhanced to allow tolerance studies of tilted and decentered surfaces, is used to calculate the size and orientation of an astigmatic blur on a quadrant photodetector as a function of focus error. The resulting irradiance distribution is integrated over the detector elements and processed to yield typical focus servo signals. A method for simulating generalized astigmatic focus systems, independent of a particular design, is also shown. The simulation results are used to derive normalized tolerance curves for detector misalignment and spot motion. Alignment diagnostics based on the servo signals are also presented. A wavefront aberration model is also developed and used to investigate the focus servo's performance in the presence of common aberrations. Simulations based on diffraction theory are used to investigate the radial tracking servo. Both scalar and vector diffraction theories are considered. The scalar theory is found to be adequate in most cases, while offering a large advantage in computational efficiency. A model for computing the signals detected by scanning the microscopic features of the disk is developed using the optical cross transfer function that describes the imaging characteristics of partially coherent systems. This model is used to investigate push-pull and three beam tracking. Aberrations, data patterns, detector misalignment, and pregroove profile are all examined for their effects on the servo signals. Crosstalk between the focus and tracking error detection is also briefly considered, and a possible extension of the radial tracking servo model to investigate this phenomenon is suggested.

This diploma thesis deals with computer simulation. In the opening, there are descriptions of theoretical aspect of computer simulation, simulation model structure and individual phases of simulation process. After that follow areas of application, characteristic features of each area and classification of simulation models, that are used in those areas. In this thesis only 4 areas of application were chosen: automotive industry, logistics and transportation systems, healthcare and military simulation. Each application area contains descriptions of a few chosen simulation software products that are used in this area. At the close there is a price comparison of described simulation products, their usage in Czech Republic and their development evaluation.

Afin de lutter contre les allergies alimentaires, la société pharmaceutique DBV Technologies propose un patch épicutané permettant un traitement efficace, la plateforme Viaskin ®.Pour envisager de nouveaux moyens de production de ce patch, nous avons étudié dans cette thèse le procédé d'aérospray (AS).Pour cela, nous avons développé des modèles numériques des différentes parties spatiales de l'AS.Dans un premier temps, nous étudions le cône de liquide formé à la sortie de buse d'AS. L'approche diphasique est traitée à l'aide de la méthode de champ de phase (dite à interface diffuse), dans laquelle l'équation de Cahn-Hilliard gouverne la fonctionnelle d'interface.Deux régimes principaux sont identifiés : le régime Stationnaire Dynamique, où le cône de liquide est stable, et le régime Transitoire, où sa dynamique est périodique.Dans ce second régime, les résultats du modèle ont montré une évolution discontinue de la période d'oscillation du cône en fonction du débit liquide. Nous avons corrélé ce phénomène avec des oscillations capillaires du cône, et comparé avec succès les résultats des simulations numériques aux résultats expérimentaux.Dans un second temps, la fragmentation du jet de liquide produit par le cône est étudiée numériquement, et comparée aux résultats d'analyses de stabilité linéaire produites dans la littérature. Le modèle proposé est une méthode utilisant un maillage mobile, à interface nette.Nous avons montré que la taille des gouttelettes produites variait peu en fonction de la pression de gaz appliquée.L'ensemble des travaux permet de comprendre les phénomènes physiques sous-jacents à l'AS, et à sélectionner dans une optique industrielle les modes optimaux de fonctionnement. / In order to fight against food allergies, the pharmaceutical company DBV Technologies offers an epicutaneous patch for effective treatment, the Viaskin ® platform.To consider new ways of producing this patch, we studied in this thesis the aerospray (AS) process.For this, we have developed numerical models of the different spatial parts of the AS.First, we study the cone of liquid formed at the nozzle exit of AS. The two-phase approach is processed using the so-called diffuse interface phase field method, in which the Cahn-Hilliard equation governs the interface functional.Two main regimes are identified: the Stationary Dynamic flow regime, where the liquid cone is stable, and the Transient regime, where its motion is periodic.In this second regime, the results of the model showed a discontinuous evolution of the oscillation period of the cone as a function of the liquid flow. We have correlated this phenomenon with capillary oscillations of the cone, and successfully compared the results of the numerical simulations to the experimental results.In a second time, the fragmentation of the liquid jet produced by the cone is studied numerically, and compared to the results of linear stability analyzes produced in the literature. The proposed model is a method using a mobile mesh, with a net interface.We have shown that the size of droplets produced varies little according to the applied gas pressure.All of this work improves the understanding of the physical phenomena underlying the AS, and to select from an industrial point of view the optimal modes of operation.