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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.
131

Comparing generalized additive neural networks with multilayer perceptrons / Johannes Christiaan Goosen

Goosen, Johannes Christiaan January 2011 (has links)
In this dissertation, generalized additive neural networks (GANNs) and multilayer perceptrons (MLPs) are studied and compared as prediction techniques. MLPs are the most widely used type of artificial neural network (ANN), but are considered black boxes with regard to interpretability. There is currently no simple a priori method to determine the number of hidden neurons in each of the hidden layers of ANNs. Guidelines exist that are either heuristic or based on simulations that are derived from limited experiments. A modified version of the neural network construction with cross–validation samples (N2C2S) algorithm is therefore implemented and utilized to construct good MLP models. This algorithm enables the comparison with GANN models. GANNs are a relatively new type of ANN, based on the generalized additive model. The architecture of a GANN is less complex compared to MLPs and results can be interpreted with a graphical method, called the partial residual plot. A GANN consists of an input layer where each of the input nodes has its own MLP with one hidden layer. Originally, GANNs were constructed by interpreting partial residual plots. This method is time consuming and subjective, which may lead to the creation of suboptimal models. Consequently, an automated construction algorithm for GANNs was created and implemented in the SAS R statistical language. This system was called AutoGANN and is used to create good GANN models. A number of experiments are conducted on five publicly available data sets to gain insight into the similarities and differences between GANN and MLP models. The data sets include regression and classification tasks. In–sample model selection with the SBC model selection criterion and out–of–sample model selection with the average validation error as model selection criterion are performed. The models created are compared in terms of predictive accuracy, model complexity, comprehensibility, ease of construction and utility. The results show that the choice of model is highly dependent on the problem, as no single model always outperforms the other in terms of predictive accuracy. GANNs may be suggested for problems where interpretability of the results is important. The time taken to construct good MLP models by the modified N2C2S algorithm may be shorter than the time to build good GANN models by the automated construction algorithm / Thesis (M.Sc. (Computer Science))--North-West University, Potchefstroom Campus, 2011.
132

Comparing generalized additive neural networks with multilayer perceptrons / Johannes Christiaan Goosen

Goosen, Johannes Christiaan January 2011 (has links)
In this dissertation, generalized additive neural networks (GANNs) and multilayer perceptrons (MLPs) are studied and compared as prediction techniques. MLPs are the most widely used type of artificial neural network (ANN), but are considered black boxes with regard to interpretability. There is currently no simple a priori method to determine the number of hidden neurons in each of the hidden layers of ANNs. Guidelines exist that are either heuristic or based on simulations that are derived from limited experiments. A modified version of the neural network construction with cross–validation samples (N2C2S) algorithm is therefore implemented and utilized to construct good MLP models. This algorithm enables the comparison with GANN models. GANNs are a relatively new type of ANN, based on the generalized additive model. The architecture of a GANN is less complex compared to MLPs and results can be interpreted with a graphical method, called the partial residual plot. A GANN consists of an input layer where each of the input nodes has its own MLP with one hidden layer. Originally, GANNs were constructed by interpreting partial residual plots. This method is time consuming and subjective, which may lead to the creation of suboptimal models. Consequently, an automated construction algorithm for GANNs was created and implemented in the SAS R statistical language. This system was called AutoGANN and is used to create good GANN models. A number of experiments are conducted on five publicly available data sets to gain insight into the similarities and differences between GANN and MLP models. The data sets include regression and classification tasks. In–sample model selection with the SBC model selection criterion and out–of–sample model selection with the average validation error as model selection criterion are performed. The models created are compared in terms of predictive accuracy, model complexity, comprehensibility, ease of construction and utility. The results show that the choice of model is highly dependent on the problem, as no single model always outperforms the other in terms of predictive accuracy. GANNs may be suggested for problems where interpretability of the results is important. The time taken to construct good MLP models by the modified N2C2S algorithm may be shorter than the time to build good GANN models by the automated construction algorithm / Thesis (M.Sc. (Computer Science))--North-West University, Potchefstroom Campus, 2011.
133

Vyhledávání ve videu / Video Retrieval

Černý, Petr January 2012 (has links)
This thesis summarizes the information retrieval theory, the relational model basic and focuses on the data indexing in relational database systems. The thesis focuses on multimedia data searching. It includes description of automatic multimedia data content extraction and multimedia data indexing. Practical part discusses design and solution implementation for improving query effectivity for multidimensional vector similarity which describes multimedia data. Thesis final part discusses experiments with this solution.
134

Reusage classification of damaged Paper Cores using Supervised Machine Learning

Elofsson, Max, Larsson, Victor January 2023 (has links)
This paper consists of a project exploring the possibility to assess paper code reusability by measuring chuck damages utilizing a 3D sensor and usingMachine Learning to classify reusage. The paper cores are part of a rolling/unrolling system at a paper mill whereas a chuck is used to slow and eventually stop the revolving paper core, which creates damages that at a certain point is too grave for reuse. The 3D sensor used is a TriSpector1008from SICK, based on active triangulation through laser line projection and optic sensing. A number of paper cores with damages varying in severity labeled approved or unapproved for further use was provided. SupervisedLearning in the form of K-NN, Support Vector Machine, Decision Trees andRandom Forest was used to binary classify the dataset based on readings from the sensor. Features were extracted from these readings based on the spatial and frequency domain of each reading in an experimental way.Classification of reusage was previously done through thresholding on internal features in the sensor software. The goal of the project is to unify the decision making protocol/system with economical, environmental and sustainable waste management benefits. K-NN was found to be best suitedin our case. Features for standard deviation of calculated depth obtained from the readings, performed best and lead to a zero false positive rate and recall score of 99.14%, outperforming the compared threshold system. / Den här rapporten undersöker möjligheten att bedöma papperskärnors återanvändbarhet genom att mäta chuck skador med hjälp av en 3D-sensor för att genom maskininlärning klassificera återanvändning. Papperskärnorna används i ett rullnings-/avrullningssystem i ett pappersbruk där en chuck används för att bromsa och till sist stoppa den roterande papperskärnan, vilket skapar skador som vid en viss punkt är för allvarliga för återanvändning. 3D-sensorn som används är en TriSpector1008 från SICK,baserad på aktiv triangulering genom laserlinje projektion och optisk avläsning. Projektet försågs med ett antal papperskärnor med varierande skador, märkta godkända eller ej godkända för vidare användning av leverantören. Supervised Learning i form av K-NN, Support VectorMachine, Decision Trees och Random Forest användes för att binärt klassificera datasetet baserat på avläsningar från sensorn. Features Extraherades från dessa avläsningar baserat på spatial och frekvensdomänen för varje avläsning på ett experimentellt sätt. Klassificering av återanvändning gjordes tidigare genom tröskelvärden på interna features isensorns mjukvara. Målet med projektet är att skapa ett enhetligtbeslutsprotokoll/system med ekonomiska, miljömässiga och hållbaraavfallshanteringsfördelar. K-NN visades vara bäst lämpad för projektet.Featuerna representerande standardavvikelse för beräknat djup som erhållits från avläsningarna visades vara bäst och leder till en false positive rate lika med noll och recall score på 99.14%, vilket överpresterade det jämförda tröskel systemet.
135

Methods for face detection and adaptive face recognition

Pavani, Sri-Kaushik 21 July 2010 (has links)
The focus of this thesis is on facial biometrics; specifically in the problems of face detection and face recognition. Despite intensive research over the last 20 years, the technology is not foolproof, which is why we do not see use of face recognition systems in critical sectors such as banking. In this thesis, we focus on three sub-problems in these two areas of research. Firstly, we propose methods to improve the speed-accuracy trade-off of the state-of-the-art face detector. Secondly, we consider a problem that is often ignored in the literature: to decrease the training time of the detectors. We propose two techniques to this end. Thirdly, we present a detailed large-scale study on self-updating face recognition systems in an attempt to answer if continuously changing facial appearance can be learnt automatically. / L'objectiu d'aquesta tesi és sobre biometria facial, específicament en els problemes de detecció de rostres i reconeixement facial. Malgrat la intensa recerca durant els últims 20 anys, la tecnologia no és infalible, de manera que no veiem l'ús dels sistemes de reconeixement de rostres en sectors crítics com la banca. En aquesta tesi, ens centrem en tres sub-problemes en aquestes dues àrees de recerca. En primer lloc, es proposa mètodes per millorar l'equilibri entre la precisió i la velocitat del detector de cares d'última generació. En segon lloc, considerem un problema que sovint s'ignora en la literatura: disminuir el temps de formació dels detectors. Es proposen dues tècniques per a aquest fi. En tercer lloc, es presenta un estudi detallat a gran escala sobre l'auto-actualització dels sistemes de reconeixement facial en un intent de respondre si el canvi constant de l'aparença facial es pot aprendre de forma automàtica.

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