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  • 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.
481

COMPARATIVE STUDIES OF DIFFUSION MODELS AND ARTIFICIAL NEURAL INTELLIGENCE ON ELECTROCHEMICAL PROCESS OF U AND Zr DISSOLUTIONS IN LiCl-KCl EUTECTIC SALTS

Rakhshan Pouri, Samaneh 01 January 2017 (has links)
The electrorefiner (ER) is the heart of pyroprocessing technology operating at a high-temperature (723 K – 773 K) to separate uranium from Experimental Breeder Reactor-II (EBR-II) used metallic fuel. One of the most common electroanalytical methods for determining the thermodynamic and electrochemical behavior of elemental species in the eutectic molten salt LiCl-KCl inside ER is cyclic voltammetry (CV). Information from CV can possibly be used to estimate diffusion coefficients, apparent standard potentials, transfer coefficients, and numbers of electron transferred. Therefore, predicting the trace of each species from the CV method in an absence of experimental data is important for safeguarding this technology. This work focused on the development an interactive computational design for the CV method by analyzing available uranium chloride data sets (1 to 10 wt%) in a LiCl-KCl molten salt at 773 K under different scan rates to help elucidating, improving, and providing robustness in detection analysis. A principle method and a computational code have been developed by using electrochemical fundamentals and coupling various variables such as: the diffusion coefficients, formal potentials, and process time duration. Although this developed computational model works moderately well with reported uranium data sets, it experiences difficulty in tracing zirconium data sets due to their complex CV structures. Therefore, an artificial neural intelligent (ANI) data analysis has been proposed to resolve this issue and to provide comparative study to the precursor computational modeling development. For this purpose, ANI has been applied on 0.5 to 5 wt% of zirconium chloride in LiCl-KCl eutectic molten salt at 773 K under different scan rates to mimic the system and provide current and potential simulated data sets for the unseen data. In addition, a Graphical User Interface (GUI) through the commercial software Matlab was created to provide a controllable environment for different users. The computational code shows a limitation in high concentration CV prediction, capturing the adsorption peaks, and provides a dissimilarity. However, the model is able to capture the important anodic and cathodic peaks of uranium chloride CV which is the main focus of this study. Furthermore, the developed code is able to calculate the concentration of each species as a function of time. Due to the complexity of the CV of zirconium chloride, the computational model is used to predict the probability reactions occurring at each peak. The resulting study reveals that the reaction at the highest anodic peak is related to the combination of 70% Zr/Zr+4 and 30% Zr/Zr+2 for the 1.07 wt% and 2.49 wt% zirconium chloride and 30% Zr/Zr+4 and 70% Zr/Zr+2 combination for 4.98 wt% ZrCl4. The proposed alternative ANI method has demonstrated its capability in predicting the trend of species in a new situation with a high accuracy on predictions without any dissimilarity. Two final structures from zirconium chloride study which high accuracy (that is, a low error) are related to [9, 15, 10]-18 and [10, 11, 25]-19. These two final structures have been applied on uranium chloride salt experimental data sets to further validate the ANI’s ability and concept. Three different fixed data combinations were considered. The result indicates that by increasing the number of training data sets it does not necessarily help improving the prediction process. ANI implementation outcome on uranium chloride data set illustrates a good prediction with a specific fixed data combination and [9, 15, 10]-18 structure. Thus, it can be concluded that ANI is a promising method for safeguarding pyroprocessing technology due to its robustness in predicting the CV plots with high accuracy.
482

Comprehensive fluid saturation study for the Fula North field Muglad Basin, Sudan

Altayeb, Abdalmajid I. H. January 2016 (has links)
>Magister Scientiae - MSc / This study has been conducted to accurately determine fluid saturation within Fula sub-basin reservoirs which is located at the Southern part of the Republic of Sudan. The area is regarded as Shaly Sand Reservoirs. Four deferent shaly sand lithofacies (A, B, C, D) have been identified. Using method based on the Artificial Neural Networks (ANN), the core surrounding facies, within Fula reservoirs were identified. An average shale volume of 0.126 within the studied reservoirs was determined using gamma ray and resistivity logs. While average porosity of 26.7% within the reservoirs was determined using density log and the average core grain density. An average water resistivity of 0.8 Ohm-m was estimated using Pickett plot method. While formation temperature was estimated using the gradient that constrained between surface and bottom hole temperature. Water saturation was determined using Archie model and four shaly sand empirical models, the calculation was constrained within each facies zone to specify a model for each facies, and another approach was used to obtain the water saturation based on Artificial Neural Networks. The net pay was identified for each reservoir by applying cut-offs on permeability 5 mD, porosity 16%, shale volume 0.33, and water saturation 0.65. The gross thickness of the reservoirs ranges from 7.62m to 19.85m and net pay intervals from 4.877m to 19.202m. The study succeeded in establishing water saturation model for the Fula sub-basin based on neural networking which was very consistent with the core data, and hence has been used for net pay determination.
483

Life cycle costing methodology for sustainable commerical office buildings

Oduyemi, Olufolahan Ifeoluwa January 2015 (has links)
The need for a more authoritative approach to investment decision-making and cost control has been a requirement of office spending for many years now. The commercial offices find itself in an increasingly demanding position to allocate its budgets as wisely and prudently as possible. The significant percentage of total spending on buildings demands a more accurate and adaptable method of achieving quality of service within the constraints on the budgets. By adoption of life cycle costing techniques with risk management, practitioners have the ability to make accurate forecasts of likely future running costs. This thesis presents a novel framework (Artificial Neural Networks and probabilistic simulations) for modelling of operating and maintenance historical costs as well as economic performance measures of LCC. The methodology consisted of eight steps and presented a novel approach to modelling the LCC of operating and maintenance costs of two sustainable commercial office buildings. Finally, a set of performance measurement indicators were utilised to draw inference from these results. Therefore, the contribution that this research aimed to achieve was to develop a dynamic LCC framework for sustainable commercial office buildings, and by means of two existing buildings, demonstrate how assumption modelling can be utilised within a probabilistic environment. In this research, the key themes of risk assessment, probabilistic assumption modelling and stochastic assessment of LCC has been addressed. Significant improvements in existing LCC models have been achieved in this research in an attempt to make the LCC model more accurate and meaningful to estate managers and high-level capital investment decision makers A new approach to modelling historical costs and forecasting these costs in sustainable commercial office buildings is presented based upon a combination of ANN methods and stochastic modelling of the annual forecasted data. These models provide a far more accurate representation of long-term building costs as the inherent risk associated with the forecasts is easily quantifiable and the forecasts are based on a sounder approach to forecasting than what was previously used in the commercial sector. A novel framework for modelling the facilities management costs in two sustainable commercial office buildings is also presented. This is not only useful for modelling the LCC of existing commercial office buildings as presented here, but has wider implications for modelling LCC in competing option modelling in commercial office buildings. The processes of assumption modelling presented in this work can be modified easily to represent other types of commercial office buildings. Discussions with policy makers in the real estate industry revealed that concerns were held over how these building costs can be modelled given that available historical data represents wide spending and are not cost specific to commercial office buildings. Similarly, a pilot and main survey questionnaire was aimed at ascertaining current level of LCC application in sustainable construction; ranking drivers and barriers of sustainable commercial office buildings and determining the applications and limitations of LCC. The survey result showed that respondents strongly agreed that key performance indicators and economic performance measures need to be incorporated into LCC and that it is important to consider the initial, operating and maintenance costs of building when conducting LCC analysis, respondents disagreed that the current LCC techniques are suitable for calculating the whole costs of buildings but agreed that there is a low accuracy of historical cost data.
484

Data Collection, Analysis, and Classification for the Development of a Sailing Performance Evaluation System

Sammon, Ryan January 2013 (has links)
The work described in this thesis contributes to the development of a system to evaluate sailing performance. This work was motivated by the lack of tools available to evaluate sailing performance. The goal of the work presented is to detect and classify the turns of a sailing yacht. Data was collected using a BlackBerry PlayBook affixed to a J/24 sailing yacht. This data was manually annotated with three types of turn: tack, gybe, and mark rounding. This manually annotated data was used to train classification methods. Classification methods tested were multi-layer perceptrons (MLPs) of two sizes in various committees and nearest- neighbour search. Pre-processing algorithms tested were Kalman filtering, categorization using quantiles, and residual normalization. The best solution was found to be an averaged answer committee of small MLPs, with Kalman filtering and residual normalization performed on the input as pre-processing.
485

Predikce výsledků hokejových utkání pomocí data mining modelu / Ice Hockey Match Prediction Using Data Mining Model

Matuš, Martin January 2014 (has links)
This thesis focuses on creation and comparison of ice hockey matches prediction models with the view on ice hockey world championship matches. The first part is dedicated to collecting theoretical knowledge needed for solving this problem and the second to applying this set of knowledge. The model creation approach is intertwined with the CRISP-DM data mining methodology, which also defines several chapters of this work. As input data for the models I used performance statistics of individual ice hockey players -- this brought me to implementing a script capable of automatic downloading and aggregating of player data from the Internet. Downloaded data were arranged so as they would represent ice hockey matches that were played during the championships (team A consisting of players X against team B consisting of players Y) with result of the match added to the data row. Data were also analyzed to detect any quality issue prior to the model creation and transformed into an integrated view. Result assessment consists of two parts, in the first the technical evaluation of models using data from the testing data set takes place. The first part also points out practical usefulness of the models. The next part is about comparing result data with the betting odds -- the business relevance of the model. This part uses open source data about betting odds listed on the corresponding matches. Finally, the outcome model is used for predicting matches of the group phase of the world championship taking place in Prague, 2015.
486

Souvislost volatility akciových kurzů a pozice ekonomiky v hospodářském cyklu / The Connection Between Stock Market Volatility and a Position of Economy in a Business Cycle

Poláková, Soňa January 2014 (has links)
Finding significant relation between stock markets (including omnipresent volatility) and real economy of the US, Germany, Great Britain and Japan is the main aim of this thessis. If not found it is also the final conclusion. By means of time series analysis using artificial neural networks from the beginning of 2000 till the November of 2014 was proved that the strong single -- way relation between prime stock indices and GDP of chosen economies does exist. Highest quality of prediction was proved on the American and British economy. S&P 500, FTSE and VIX indicator made a precise prediction of future economic progress in the US and Great Britain for six to nine months ahead with 71% to 86% accuracy. The artificial neural networks proved an extraordinary ability to predict chosen financial time series regardless the actual position in a business cycle.
487

Combinação de Classificadores para Reconhecimento de Padrões / Not available

Paulo Sérgio Prampero 16 March 1998 (has links)
O cérebro humano é formado por um conjunto de neurônios de diferentes tipos, cada um com sua especialidade. A combinação destes diferentes tipos de neurônios é um dos aspectos responsáveis pelo desempenho apresentado pelo cérebro na realização de várias tarefas. Redes Neurais Artificiais são técnicas computacionais que apresentam um modelo matemático inspirado no sistema nervoso e que adquirem conhecimento através da experiência. Uma alternativa para melhorar o desempenho das Redes Neurais Artificiais é a utilização de técnicas de Combinação de Classificadores. Estas técnicas de combinação exploram as diferenças e as semelhanças das redes para a obtenção de resultados melhores. Dentre as principais aplicações de Redes Neurais Artificiais está o Reconhecimento de Padrões. Neste trabalho, foram utilizadas técnicas de Combinação de Classificadores para a combinação de Redes Neurais Artificiais em problemas de Reconhecimento de Padrões. / The human brain is formed by neurons of different types, each one with its own speciality. The combination of theses different types of neurons is one of the main features responsible for the brain performance in severa! tasks. Artificial Neural Networks are computation technics whose mathematical model is based on the nervous system and learns new knowledge by experience. An alternative to improve the performance of Artificial Neural Networks is the employment of Classifiers Combination techniques. These techniques of combination explore the difference and the similarity of the networks to achieve better performance. The main application of Artificial Neural Networks is Pattern Recognition. In this work, Classifiers Combination techniques were utilized to combine Artificial Neural Networks to solve Pattern Recognition problems.
488

Extração de conhecimento de redes neurais artificiais. / Knowledge extraction from artificial neural networks.

Edmar Martineli 20 August 1999 (has links)
Este trabalho descreve experimentos realizados com Redes Neurais Artificiais e algoritmos de aprendizado simbólico. Também são investigados dois algoritmos de extração de conhecimento de Redes Neurais Artificiais. Esses experimentos são realizados com três bases de dados com o objetivo de comparar os desempenhos obtidos. As bases de dados utilizadas neste trabalho são: dados de falência de bancos brasileiros, dados do jogo da velha e dados de análise de crédito. São aplicadas sobre os dados três técnicas para melhoria de seus desempenhos. Essas técnicas são: partição pela menor classe, acréscimo de ruído nos exemplos da menor classe e seleção de atributos mais relevantes. Além da análise do desempenho obtido, também é feita uma análise da dificuldade de compreensão do conhecimento extraído por cada método em cada uma das bases de dados. / This work describes experiments carried out witch Artificial Neural Networks and symbolic learning algorithms. Two algorithms for knowledge extraction from Artificial Neural Networks are also investigates. This experiments are performed whit three data set with the objective of compare the performance obtained. The data set used in this work are: Brazilians banks bankruptcy data set, tic-tac-toe data set and credit analysis data set. Three techniques for data set performance improvements are investigates. These techniques are: partition for the smallest class, noise increment in the examples of the smallest class and selection of more important attributes. Besides the analysis of the performance obtained, an analysis of the understanding difficulty of the knowledge extracted by each method in each data bases is made.
489

Analiza dinamičkog ponašanja kugličnih ležaja primenom veštačkih neuronskih mreža / Analysis of Dynamical Behaviour of Ball Bearings Using Artificial NeuralNetworks

Knežević Ivan 03 November 2020 (has links)
<p>Predmet ove doktorske disertacije je analiza dinamičkog ponašanja<br />kotrljajnih ležaja primenom veštačkih neuronskih mreža. Na bazi<br />rezultata eksperimentalnog ispitivanja obučene su veštačke<br />neuronske mreže koje su sposobne da predvide amplitude brzine<br />vibracija ležaja. Vibracije koje ležaj generiše zavise od niza<br />uticajnih parametara koji se mogu podeliti na konstrukcione,<br />tehnološke i eksploatacione. Modeli dobijeni primenom veštačkih<br />neuronskih mreža određuju zavisnosti između uticajnih parametara i<br />amplituda brzine vibracija koje ležaj generiše. Validacija<br />neuronskih modela izvršena je na osnovu eksperimentalnih rezultata.<br />Analiziran je uticaj svakog parametra ležaja na amplitude brzine<br />vibracija u karakterističnim područjima frekvencija. U radu su<br />prikazani i rezultati međusobnog uticaja više parametara. Modelima<br />su dobijene preporučene vrednosti uticajnih parametara ležaja. Pri<br />analizi tehnoloških parametara uvedeni su: parametar ekvivalentne<br />površinske hrapavosti, parametar ekvivalentne valovitosti i<br />parametar ekvivalentnog odstupanja od kružnosti staza kotrljanja.<br />Novouvedeni parametri omogućavaju bolje razumevanje uticaja na<br />dinamičko ponašanje. U radu je pokazano da su neuronski modeli<br />sposobni da na osnovu parametara ležaja predvide klasu kvaliteta<br />ležaja.</p> / <p>The subject of this doctoral dissertation is the analysis of the dynamic<br />behavior of ball bearings using artificial neural networks. Based on the<br />results of the experimental test, artificial neural networks were trained to be<br />able to predict the amplitudes of the bearing vibration velocity. The vibrations<br />generated by the bearing depend on a number of influential parameters that<br />can be divided into construction, technological and exploitation. Models<br />obtained by applying artificial neural networks determined the dependences<br />between the influencing parameters and the amplitudes of the vibration<br />velocity generated by the bearing. Validation of neural models was<br />performed based on experimental results. The influence of each parameter<br />on the vibration velocity amplitudes in the characteristic frequency ranges<br />was analyzed. The paper also presents the results of the mutual influence of<br />several parameters. The models obtained the recommended values of the<br />influential bearing parameters. In the analysis of technological parameters,<br />the following parameters were introduced: the parameter of equivalent<br />surface roughness, the parameter of equivalent waviness and the parameter<br />of equivalent roundness error of raceways. The newly introduced parameters<br />provide a better understanding of the impact on dynamic behavior. The paper<br />shows that neural models are able to predict the bearing quality class based<br />on bearing parameters.</p>
490

Evaluating the lifting capacity in a mobile crane simulation

Roysson, Simon January 2020 (has links)
The work environment of a mobile crane is hazardous where accidents can cause serious injuries or death for workers and non-workers. Therefore, the risk for these accidents should be avoided when possible. One way to avoid the potential accidents is to use mobile crane simulations instead, which removes the risk. Because of this, simulations have been developed to train operators and plan future operations. Mobile crane simulations can also be used to perform research related to mobile cranes, but for the result to be applicable to real-world settings the simulation has to be realistic enough. Therefore, this thesis evaluated an aspect of realism which is the lifting capacity of a mobile crane. This was done by having an artificial neural network train on values from load charts of a real crane, that was then used to predict the lifting capacities based on the boom length and the load radius of the virtual crane. An experiment was conducted in the simulation that collected the predicted lifting capacities which was then compared to the lifting capacities in the load charts of a real crane. The results showed that the lifting capacities could be predicted with little to no deviation except for in a few cases. When conducting the experiment, it was found that the virtual mobile crane could not reach all load radiuses documented in the real load charts. The predicted lifting capacities are concluded to be realistic enough for crane-related research, but should be refined if the lifting capacity plays a key role in the research. Future works such as improving and generalizing the artificial network, and performing the evaluation with user tests are prompted.

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