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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.
1

Environment effects on the fractal dimension of Gracilaria tenuistpitata

Guay, Te-Juing 28 July 2004 (has links)
The effects of environmental factors were investigated in fractal dimension (D) of Gracilaria tenuistpitata. G. tenuistipitata was cultured indoors under various factors for 30 days. Algal thalli were pressed on flat surface for photopraph with optical or digital camera to measure fractal dimension based on the relationship between levels and numbers of algal branch. Environment factors in this study were including illumination (L¡F 45~365£gmol¡Em-2¡Es-1), water flow (F¡F 80~900L¡Eh-1), temperature (T¡F 10~35¢J) and salinity (S¡F 10~50 ppt). The results of ANOVA and General linear models showed that illumination, temperature and salinity but water flow significantly affected thallus fractal dimension with the maximum at 255£gmol¡Em-2¡Es-1, 19¢J and 24 ppt respectively, The cross reactions between environment factors did not significantly affect the fractal dimension, reflecting that environment factors affect the appearance of G. tenuistpitata independently. The effect of environment factors on biomass of G. tenuistpitata was studied in each experiment and the results showed that all environment factors tested in this study significantly affected the biomass of G. tenuistpitata.
2

The use of spontaneous vestibular response for diagnosis of meniere’s disease

Dastgheib, Zeinab 08 September 2016 (has links)
Meniere's disease is a common inner ear disorder that affects balance and hearing. Electrovestibulography (EVestG) is a relatively new vestibular driven test that measures spontaneous and driven field potential activity recorded in the external ear canal in response to various vestibular stimuli. The main objectives of this thesis were to record and analyze EVestG signals in order to 1) testify whether the EVestG technology is capable of classifying individuals with Meniere’s from healthy ones, and if it is, then 2) identify the EVestG tilt stimulus providing the most informative response in relation to identifying Meniere’s symptoms; thus, optimizing the EVestG experimental protocol as a Meniere’s disease diagnostic aid. EVestG signals of two groups of Meniere’s and control individuals during seven different EVestG tilt stimuli were recorded and analyzed by linear and nonlinear signal processing techniques. Data of 14 with Meniere’s disease and 16 healthy individuals were used as the training set, while additional data of 21 individuals with vertiginous disorders (and suspected of Meniere’s disease) and 10 controls were used as the test set. An ad-hoc voting classifier built upon single-feature linear classifiers was designed, and used for classification of the two groups of both training and test datasets. The results showed an overall accuracy of 87% and 84% for training and test datasets, respectively. Among the seven different tilts that each evokes a specific part of the inner ear organ, the side tilt which stimulates most of the labyrinth and particularly the utricle, was found to generate the best characteristic features for identifying Meniere’s disease from controls. Thus, one may simplify the EVestG protocol to only the side tilt stimulus for a quick screening of Meniere’s disease. The proposed method encourages the use of EVestG technology as a non-invasive and potentially reliable diagnostic/screening tool to aid clinical diagnosis of Meniere’s diseases. / October 2016
3

Elektrokardiogramos variacijos pobūdžio tyrimas / Electrocardiogram Variation Complexion Research

Antanavičius, Karolis 06 June 2006 (has links)
In our research we analyse electrocardiograms (ECG). The aim of this research is to apply the fractal dimension computing method to electrocardiograms, i.e. to create an algorithm, due to which it would be possible to get a few parameters describing ECG. Then, to check, whether the created the mathematical model for computing fractal dimension classify the possessed data. According to Hausdorf “capacity dimension” we compute and analyze “capacity coefficient”. The research of the plane “capacity coefficient” was carried out in this work (it is a fractal dimension, which was computed at the fixed dimension of the iterational window). The computing algorithm was made, with the help of which the ECG plane capacity coefficient was computed for 300 persons. When the initial information on the examined persons is known, the results are tried to be assessed from the mathematical, as well as medical, point of view.
4

Examination of the gelling properties of canola and soy protein isolates

2015 February 1900 (has links)
Canola protein isolate (CPI) has tremendous potential as a protein alternative to soy within the global protein ingredient market. The overall goal of this thesis was to compare and contrast the gelling mechanism of CPI with a commercial soy protein isolate (SPI) ingredient. Specifically, the gelation properties of CPI and SPI were evaluated as a function of protein concentration (5.0–9.0%), destabilizing agent [0.1 – 5.0 M urea; 0.1 and 1.0% 2-mercaptoethanol], ionic strength (0.1, 0.5 M NaCl) and pH (3.0, 5.0, 7.0, 9.0). The fractal properties of CPI were evaluated as a function of protein concentration (5.0 – 9.0%) and pH (3.0, 5.0, 7.0, 9.0). In the first study, the gelling properties of CPI and SPI as a function of concentration were evaluated, along with the nature of the interactions within their respective gel networks. Overall, the magnitude of the storage modulus (G') of the gel was found to increase with increasing concentration at pH 7.0, whereas the gelling temperature (Tgel) remained constant at ~88ºC. As the NaCl level was increased from 0.1 to 0.5 M, the zeta potential was found to be reduced from ~-20 to -4 mV, but with little effect on Tgel or network strength. In the presence of 2-mercaptoethanol, networks became weaker, indicating the importance of disulfide bridging within the CPI network. Disulfide bridging, electrostatics and hydrogen bonding are all thought to have a role in CPI gelation. In the case of SPI, the magnitude of the storage modulus (G') and Tgel were found to increase and decrease (~80ºC to 73ºC), respectively, with increasing urea concentration at pH 7.0. Increases in NaCl from 0.1 to 0.5 M reduced the zeta potential from ~-44 to -13 mV and caused a shift in Tgel from ~84ºC to 67ºC, and increased G'. No gels were formed in the presence of 2-mercaptoethanol. In the second study, the effect of pH on the gelling properties of CPI and SPI was evaluated. Surface charge (i.e., zeta potential) measurements as a function of pH found CPI to be positively (+18.6 mV), neutral and negatively (-32 mV) charged at pH 3.0, ~5.6 and 9.0, respectively. On the other hand, SPI was observed to be positively (+35.4 mV), neutral and negatively (-51 mV) charged at pH 3.0, 5.0 and 9.0, respectively. An increases in NaCl concentration from 0 M to 0.1 M resulted in a reduction in surface charge at all pHs for both CPI and SPI. Differential scanning calorimetry was performed to determine the thermal properties of CPI. The gelation temperature was found to be above the onset temperature for denaturation. For CPI, the onset of denaturation was found to occur at ~68ºC and then increased to ~78-79ºC at pH 7.0-9.0. With respect to rheological properties, SPI did not gel at pH 9.0, and G' declined as pH increased from 3.0 to 7.0. CPI did not gel at pH 3.0, however the network formed at pH 5.0 became stronger (higher G') as pH increased. The SPI gelling temperature at pH 3.0, 5.0 and 7.0 was observed to be ~85.6, ~46 and ~81ºC, respectively. SPI gels formed at pH 5.0 earlier due to increased protein aggregation near its isoelectric point (pI). The gelation temperature for CPI at pH 5.0 and 7.0 were similar (~88ºC), then declined at pH 9.0 (~82ºC). Network structure of CPI as a function of pH also was investigated using confocal scanning light microscopy (CSLM). As the pH became more alkaline from pH 7.0 to pH 9.0, there was a decrease in lacunarity (~0.41->~0.25). However, the fractal dimension was found to increase (from ~1.54 to ~1.82) showing that increasing the pH resulted in a more compacted CPI network. In summary, protein-protein aggregation induced either by increasing concentration or changing the pH resulted in network formation for both CPI and SPI, where both networks were thought to be stabilized by disulfide bridging and hydrogen bonding. SPI underwent protein aggregation earlier than CPI near its pI value, whereas CPI gels formed the strongest networks away from its pI under alkaline conditions. In all cases, CPI grew in diffusion-limited cluster-cluster aggregation to from the gel network.
5

Entropy and Fractal Dimension of Swallow Acceleration Signals

Paxitzis, James T., Jr. 17 August 2011 (has links)
No description available.
6

A combined experimental and numerical approach to the assessment of floc settling velocity using fractal geometry

Moruzzi, R.B., Bridgeman, John, Silva, P.A.G. 20 June 2020 (has links)
Yes / Sedimentation processes are fundamental to solids/liquid separation in water and wastewater treatment, and therefore a robust understanding of the settlement characteristics of mass fractal aggregates (flocs) formed in the flocculation stage is fundamental to optimized settlement tank design and operation. However, the use of settling as a technique to determine aggregates’ traits is limited by current understanding of permeability. In this paper, we combine experimental and numerical approaches to assess settling velocities of fractal aggregates. Using a non-intrusive in situ digital image-based method, three- and two-dimensional fractal dimensions were calculated for kaolin-based flocs. By considering shape and fractal dimension, the porosity, density and settling velocities of the flocs were calculated individually, and settling velocities compared with those of spheres of the same density using Stokes’ law. Shape analysis shows that the settling velocities for fractal aggregates may be greater or less than those for perfect spheres. For example, fractal aggregates with floc fractal dimension, Df ¼ 2.61, floc size, df > 320 μm and dp ¼ 7.5 μm settle with lower velocities than those predicted by Stokes’ law; whilst, for Df ¼ 2.33, all aggregates of df > 70 μm and dp ¼ 7.5 μm settled below the velocity calculated by Stokes’ law for spheres. Conversely, fractal settling velocities were higher than spheres for all the range of sizes, when Df of 2.83 was simulated. The ratio of fractal aggregate to sphere settling velocity (the former being obtained from fractal porosity and density considerations), varied from 0.16 to 4.11 for aggregates in the range of 10 and 1,000 μm, primary particle size of 7.5 μm and a three-dimensional fractal dimension between 2.33 and 2.83. However, the ratio decreases to the range of 0.04–2.92 when primary particle size changes to 1.0 μm for the same fractal dimensions. Using the floc analysis technique developed here, the results demonstrate the difference in settlement behaviour between the approach developed here and the traditional Stokes’ law approach using solid spheres. The technique and results demonstrate the improvements in understanding, and hence value to be derived, from an analysis based on fractal, rather than Euclidean, geometry when considering flocculation and subsequent clarification performance / Rodrigo B. Moruzzi is grateful to São Paulo Research Foundation (Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP) Grant 2017/19195-7 for financial support and to CNPq for the fellowship Grant 301210/2018-7.
7

Node Localization using Fractal Signal Preprocessing and Artificial Neural Network

Kaiser, Tashniba January 2012 (has links)
This thesis proposes an integrated artificial neural network based approach to classify the position of a wireless device in an indoor protected area. Our experiments are conducted in two different types of interference affected indoor locations. We found that the environment greatly influences the received signal strength. We realized the need of incorporating a complexity measure of the Wi-Fi signal as additional information in our localization algorithm. The inputs to the integrated artificial neural network were comprised of an integer dimension representation and a fractional dimension representation of the Wi-Fi signal. The integer dimension representation consisted of the raw signal strength, whereas the fractional dimension consisted of a variance fractal dimension of the Wi-Fi signal. The results show that the proposed approach performed 8.7% better classification than the “one dimensional input” ANN approach, achieving an 86% correct classification rate. The conventional Trilateration method achieved only a 47.97% correct classification rate.
8

Estimação da dimensão fractal de imagens de SPM / Estimating fractal dimension of SPM images

Pinto, Silvia Cristina Dias 26 October 2001 (has links)
Este trabalho utiliza o método da Salsicha de Minkowski usando dilatação exata para estimação da dimensão fractal em imagens de superfícies de SPM (Microscópio de Varredura por Ponta de prova). Descrevemos uma rotina que permite o cálculo de uma série de dilatações da superfície original em relação a vários raios. O método de dilatação exata considera todas as possíveis salsichas envolvendo um pré-cálculo das distâncias (raios) numa grade ortogonal, que são armazenadas em uma lista junto com suas coordenadas relativas. A partir daí, realizamos um estudo multiescala sobre a curva log-log do volume dilatado em termos dos raios a fim de obter o valor da dimensão fractal para a superfície analisada. Para isso aplicamos dois métodos numéricos exatos, os quais são baseados em: diferenciação da curva por diferenças finitas e, por diferenciação usando uma propriedade da Transformada de Fourier. Os valores da derivada do sinal obtido permitem caracterizar a evolução da dimensão fractal da superfície ao longo de várias escalas espaciais, isto é, a dimensão fractal apresenta um comportamento dinâmico em termos de escalas espaciais definida pelos raios. / This work uses the Minkowski Sausage method using exact dilation for estimating fractal dimension to SPM (Scanning Probe Microscopy) surface images. We describe a routine that permits the calculation of a series of dilations of the original surface, with respect to several radii. The exact dilation method considers all the possible sausages, involving pre-calculation of the distances (radiuses) in the orthogonal lattice, which are stored into a list together with the relative coordinates. Afterwards, we did a multiscale analysis of the log-log plot of the dilated volume in terms of radiuses, in order to obtain the dimension fractal of the studied surface. For this we applied two accurate numerical methods, which are based: on the differentiation by Finite Difference and, by differentiation using a Fourier transform property. The derivative values obtained allow to characterize the evolution of the fractal dimension of the surface along several spatial scales, i.e., the fractal dimension presents a dynamic behavior in terms of different spatial scales defined by radiuses.
9

Análise fractal de redes de canais de bacias hidrográficas na escala 1:50.000 / Fractal analysis of hydrographic basin drainage network

Gomes, Maria Helena Rodrigues 14 November 1997 (has links)
Pesquisas têm sido realizadas visando a investigação das características fractais das redes de drenagem de bacias hidrográficas, com base na geomorfologia clássica proposta por HORTON (1945). A dimensão fractal foi introduzida na hidrologia por MANDELBROT (1977) e usada por vários autores, com intuito de analisar as características das redes de drenagem. O presente trabalho explora este conceito, utilizando três bacias hidrográficas do estado de São Paulo. Analisaram-se os mapas topográficos das bacias a fim de obter-se os parâmetros geomorfológicos necessários. Realizou-se a análise da dimensão fractal por métodos gráficos, como também a relação entre a dimensão fractal e as razões de Horton. Os resultados obtidos foram comparadas com aqueles encontrados na literatura e verificou-se que as bacias hidrográficas, usadas nesta pesquisa, podem ser vistas como objetos fractais com uma dimensão fractal característica. / There have been a number of investigations on the fractal characteristics of hydrographic basin drainage networks on the basis in the classical geomorfological proposed by HORTON (1945). The fractal dimension was introduced in hydrology by MANDELBROT (1977) and used by various authors in order to analyse drainage network characteristics. This study explores this concept in three hydrographic basins in the State of São Paulo. The topographic maps were employed to obtain the geomorphological parameters and fractal dimensions. Fractal analysis was performed by graphical methods and the relationship between fractal dimensions and Horton geomorphological laws was studied. The results obtained in this study are compared to those found in literature. It is verified that the basin employed in this research may be considered as fractal objects with a characteristic fractal dimension.
10

Análise fractal de redes de canais de bacias hidrográficas na escala 1:50.000 / Fractal analysis of hydrographic basin drainage network

Maria Helena Rodrigues Gomes 14 November 1997 (has links)
Pesquisas têm sido realizadas visando a investigação das características fractais das redes de drenagem de bacias hidrográficas, com base na geomorfologia clássica proposta por HORTON (1945). A dimensão fractal foi introduzida na hidrologia por MANDELBROT (1977) e usada por vários autores, com intuito de analisar as características das redes de drenagem. O presente trabalho explora este conceito, utilizando três bacias hidrográficas do estado de São Paulo. Analisaram-se os mapas topográficos das bacias a fim de obter-se os parâmetros geomorfológicos necessários. Realizou-se a análise da dimensão fractal por métodos gráficos, como também a relação entre a dimensão fractal e as razões de Horton. Os resultados obtidos foram comparadas com aqueles encontrados na literatura e verificou-se que as bacias hidrográficas, usadas nesta pesquisa, podem ser vistas como objetos fractais com uma dimensão fractal característica. / There have been a number of investigations on the fractal characteristics of hydrographic basin drainage networks on the basis in the classical geomorfological proposed by HORTON (1945). The fractal dimension was introduced in hydrology by MANDELBROT (1977) and used by various authors in order to analyse drainage network characteristics. This study explores this concept in three hydrographic basins in the State of São Paulo. The topographic maps were employed to obtain the geomorphological parameters and fractal dimensions. Fractal analysis was performed by graphical methods and the relationship between fractal dimensions and Horton geomorphological laws was studied. The results obtained in this study are compared to those found in literature. It is verified that the basin employed in this research may be considered as fractal objects with a characteristic fractal dimension.

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