Worldwide, multiple countries are investing a great deal of time and energy towards developing a new class of technologically advanced nuclear reactors. These new reactors have come to be known as the Generation IV (Gen IV) class of nuclear reactors. Similarly to the other designs, the Gas Fast Reactor (GFR) has many advantages, such as electricity production at high efficiency, hydrogen production, minor actinide burning capabilities, etc. However, there are currently no immediate plans to build a GFR due to uncertainties regarding safety issues. The study conducted herein contains input techniques for the development of new neutronic and thermal hydraulic input decks for the United States (US) Department of Energy (DOE) GFR design. The Monte Carlo N-Particle (MCNP) and MELCOR codes are used to model neutronic and thermal hydraulic characteristics, respectively. These codes are used with the intention of gaining further insight into GFR design and steady state operating characteristics of the US DOE GFR. Descriptions of inputs for all input decks, along with the results of the execution of both input decks can be found in this thesis. Although many alterations are made to original design specifications, results found in this thesis support the design modifications that have been made. Results suggest that steady-state operation of the GFR is a plausible possibility, given the right conditions. The lack of design criteria for both the reflector and borated shield regions imposes a necessity of invention upon all those who seek to clarify design criteria for the US DOE GFR. Furthermore, resulting temperature profiles for the fuel, cladding and coolant give rise to the possibility of the design of a system, based on thermionic principles, that converts core thermal energy directly to electricity. Such a system is envisioned to provide electricity to a decay heat removal system and possibly increase plant efficiency.

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In the near future, multimedia will form the majority of Internet traffic and the most popular standard used to transport and view video is MPEG. The MPEG media content data is in the form of a time-series representing frame/VOP sizes. This time-series is extremely noisy and analysis shows that it has very long-range time dependency making it even harder to predict than any typical time-series. This work is an effort to develop multi-step-ahead predictors for the moving averages of frame/VOP sizes in MPEG-coded video streams. In this work, both linear and non-linear system identification tools are used to solve the prediction problem, and their performance is compared. Linear modeling is done using Auto-Regressive Exogenous (ARX) models and for non linear modeling, Artificial Neural Networks (ANN) are employed. The different ANN architectures used in this work are Feed-forward Multi-Layer Perceptron (FMLP) and Recurrent Multi-Layer Perceptron (RMLP). Recent researches by Adas (October 1998), Yoo (March 2002) and Bhattacharya et al. (August 2003) have shown that the multi-step-ahead prediction of individual frames is very inaccurate. Therefore, for this work, we predict the moving average of the frame/VOP sizes instead of individual frame/VOPs. Several multi-step-ahead predictors are developed using the aforementioned linear and non-linear tools for two/four/six/ten-step-ahead predictions of the moving average of the frame/VOP size time-series of MPEG coded video source traffic. The capability to predict future frame/VOP sizes and hence the bit rates will enable more effective bandwidth allocation mechanism, assisting in the development of advanced source control schemes needed to control multimedia traffic over wide area networks, such as the Internet.

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Recent emphasis has been placed on merging regional forest inventory data with satellite-based information both to improve the efficiency of estimates of population totals, and to produce regional maps of forest variables. There are numerous ways in which forest class and structure variables may be modeled as functions of remotely sensed variables, yet surprisingly little work has been directed at surveying modem statistical techniques to determine which tools are best suited to the tasks given multiple objectives and logistical constraints. Here, a series of analyses to compare nonlinear and nonparametric modeling techniques for mapping a variety of forest variables, and for stratification of field plots, was conducted using data in the Interior Western United States. The analyses compared four statistical modeling techniques for predicting two discrete and four continuous forest inventory variables. The modeling techniques include generalized additive models (GAMs), classification and regression trees (CARTs), multivariate adaptive regression splines (MARS), and artificial neural networks (ANNs). Alternative stratification schemes were also compared for estimating population totals. The analyses were conducted within six ecologically different regions using a variety of satellite-based predictor variables. The work resulted in the development of an objective modeling box that automatically models spatial response variables as functions of any assortment of predictor variables through the four nonlinear or nonparametric modeling techniques. In comparing the different modeling techniques, all proved themselves workable in an automated environment, though ANNs were more problematic. When their potential mapping ability was explored through a simple simulation, tremendous advantages were seen in use of MARS and ANN for prediction over GAMs, CART, and a simple linear model. However, much smaller differences were seen when using real data. In some instances, a simple linear approach worked virtually as well as the more complex models, while small gains were seen using more complex models in other instances. In real data runs, MARS performed (marginally) best most often for binary variables, while GAMs performed (marginally) best most often for continuous variables. After considering a subjective "ease of use" measure, computing time and other predictive performance measures, it was determined that MARS had many advantages over other modeling techniques. In addition, stratification tests illustrated cost-effective means to improve precision of estimates of forest population totals. Finally, the general effect of map accuracy on the relative precision of estimates of population totals obtained under simple random sampling compared to that obtained under stratified random sampling was established and graphically illustrated as a tool for management decisions.

<p>Variability in complex systems offering rich set of features is a seriouschallenge to their users in term of flexibility with many possible variants fordifferent application contexts and maintainability. During the long period oftime, much effort has been made to deal with these issues. An effort in thisregard is developing and implementing different variability modelingtechniques.This thesis argues the explanation of three modeling techniques namedconfigurable components, feature models and function-means trees. The maincontribution to the research includes:• A comparison of above mentioned variability modeling techniques in asystematic way,• An attempt to find the integration possibilities of these modelingtechniques based on literature review, case studies, comparison,discussions, and brainstorming.The comparison is based on three case studies each of which is implemented inall above mentioned three modeling techniques and a set of generic aspects ofthese techniques which are further divided into characteristics. At the end, acomprehensive discussion on the comparison is presented and in final sectionsome integration possibility are proposed on the basis of case studies,characteristics, commonalities and experience gained through theimplementation of case studies and literature review.</p>

Dissertation submitted to the Department of Psychology, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Arts. / The aim of the present study was to develop and evaluate a process model linking stressful environmental change, perceived job insecurity and stress reactions, A review of the literature revealed that stressful changes in the environment are linked to individual stress reactions, Stress theory has also recognised that appraisal of a stressful situation leads to stress reactions, Moreover, the literature has identified job Insecurity as a form of appraisal in that it is an internal event reflecting a transformation of beliefs about what 's happening in the organisation and environment. Job insecurity in turn has been shown to result in various stress reactions in individuals, Based on such research and theorising, a causal model was developed and tested using structural equation modeling techniques, It was assessed whether: stressful environmental change impacted upon stress reactions and job insecurity; job insecurity impacted upon stress reactions; and whether Job insecurity operated as a form of appraisal in mediating the relationship between stressful environmental change and stress reactions, The Independent variable, stressful environmental change, was specified as a common factor of the measured variables, political change, social change and organisational change, The proposed mediator variable, job insecurity, was specified as a common factor of the measured variables perceived threat to total job multiplied by powerlessness, and perceived threat to job features multiplied by powerlessness, The dependent variable, stress reactions, was specified as a common factor of the measured variables psychological distress, job dissatisfaction and reduced organisational commitment. The model was tested empirically using a combined sample of 267 subjects from three organisations, Results indicated that all relationships In the proposed model were confirmed, and that a reasonable fit was demonstrated between the empirical data and the theoretical model. Stressful environmental change was causally related to both stress reactions and Job insecurity, Job Insecurity was causally related to stress reactions, and in addition operated as a partial mediator between stressful environmental change and stress reacdons. Conceptual and methodological reasons for the findings are discussed, as well as some theoretical and practical implications, Limitations in the methodology are identified and future considerations of research are suggested, / AC2017

Técnicas de modelagem baseada em imagens têm recebido considerável atenção da comunidade de visualização computacional devido ao potencial de criar cenas realistas a partir de um pequeno conjunto de imagens bi-dimensionais. Entretanto, a qualidade dos modelos gerados pelas ferramentas atualmente disponíveis é extremamente dependente de entradas fornecidas pelo usuário. Este trabalho propõe a execução do projeto de uma ferramenta de auxílio para sistemas de modelagem baseada em imagens que utiliza o conceito de contornos ativos para aumentar o grau de automação do processo de localização do contorno do objeto presente na fotografia, que servirá de guia para a posterior localização dos vértices desse objeto. Através desta abordagem, figuras geométricas mais simples, como pirâmides e hexaedros, puderam ser reconstruídas após a recuperação das coordenadas de seus vértices / Image Based Modelling techniques has received considerable attention from the computer vision community due to the potential to create realistic scenes from some bi-dimensional images. However, the model?s quality generated by the tools available nowadays is extremely dependent on entries provided by the user. This work proposes the execution of a help tool project for image based modelling systems that uses the active contours concept to increase the process automation degree of locating the contour of an object in the image, which will guide the vertex location process of this object. Through this approach, simple geometric figures, as pyramids and squares, could be reconstructed after the vertex coordinates recuperation

Técnicas de modelagem baseada em imagens têm recebido considerável atenção da comunidade de visualização computacional devido ao potencial de criar cenas realistas a partir de um pequeno conjunto de imagens bi-dimensionais. Entretanto, a qualidade dos modelos gerados pelas ferramentas atualmente disponíveis é extremamente dependente de entradas fornecidas pelo usuário. Este trabalho propõe a execução do projeto de uma ferramenta de auxílio para sistemas de modelagem baseada em imagens que utiliza o conceito de contornos ativos para aumentar o grau de automação do processo de localização do contorno do objeto presente na fotografia, que servirá de guia para a posterior localização dos vértices desse objeto. Através desta abordagem, figuras geométricas mais simples, como pirâmides e hexaedros, puderam ser reconstruídas após a recuperação das coordenadas de seus vértices / Image Based Modelling techniques has received considerable attention from the computer vision community due to the potential to create realistic scenes from some bi-dimensional images. However, the model?s quality generated by the tools available nowadays is extremely dependent on entries provided by the user. This work proposes the execution of a help tool project for image based modelling systems that uses the active contours concept to increase the process automation degree of locating the contour of an object in the image, which will guide the vertex location process of this object. Through this approach, simple geometric figures, as pyramids and squares, could be reconstructed after the vertex coordinates recuperation

No description available.