• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 4
  • 1
  • Tagged with
  • 10
  • 10
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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

Fraktalinių dimensijų skaičiavimas kai kurioms žmogaus organizmo fiziologinių procesų realizacijoms / Counting of Fractal Dimensions for Some Physiological Process Realizations of Human Organism

Ašeriškytė, Dovilė 08 June 2005 (has links)
For correct specification human’s physiological state, it is very important to evaluate the changes of main human organism systems. Fractal dimensions of the parameters of the human organism, according to proposed model which includes three functional elements – periphery, regulation and supplying systems were analyzed. The parameters that characterize the function of those systems, that is <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=22&k=heart%20rate" onmouseover="window.status='heart rate'; return true;" onmouseout="window.status='; return true;">heart rate</a>, JT interval, systolic and diastolic <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=22&k=blood%20pressure" onmouseover="window.status='blood pressure'; return true;" onmouseout="window.status='; return true;">blood pressure</a> have been studied. Interpolation of discrete data from the physical load obtained by provocative incremental bicycle ergometry stress test was made by cubic spline. For those approximated parameters fractal dimensions (capacity, information, correlation) were counted. The differences for various groups of persons (sportsmen, healthy persons, patients with ischemic heart disease) were investigated. Fractal dimensions integrates all features of reaction to load and recovery. The study revealed that distributions of fractal dimensions significantly differs between... [to full text]
2

Análise e simulação de padrões de fraturas geológicas

Gioveli, Izabel January 2010 (has links)
Os padrões de fratura são objeto de intensas investigações em várias áreas do conhecimento. Além disso, a busca por métodos matemáticos para simulação de mapas de fratura em meios geológicos tem sido alvo de muitas investigações. Este trabalho apresenta um estudo sobre a dimensão fractal de padrões de fraturas geológicas e a simulação de um mapa de fratura geológica através da análise fractal de áreas estruturalmente homogêneas na região Central do Brasil. As dimensões fractais são determinadas pelos métodos Box-counting e Cantor’s Dust num sistema anisotrópico de fraturas, a fim de caracterizar áreas geológicas selecionadas. A dimensão fractal obtida pelo método Box-counting possui valores entre um e dois, mas não permite analisar anisotropias de comprimento das fraturas, ou mesmo na sua distribuição espacial. A dimensão fractal obtida com o método de Cantor’s Dust, por outro lado, possui valores entre zero e um e fornece mecanismos adequados à avaliação da anisotropia das redes de fraturas geológicas. Deve-se observar, a partir dos resultados obtidos, que a dimensão fractal (Cantor’s Dust) depende das direções de fratura e que o número de interseções de fraturas aumenta com a diminuição da dimensão fractal. A dimensão fractal (Cantor’s Dust) também varia conforme a direção da rede de linhas ortogonais, indicando o caráter levemente anisotrópico dos padrões de fratura geológica sob análise. A análise estrutural dos padrões de fratura foi efetuada sobre as direções, o comprimento e a freqüência das fraturas de cada área homogênea. Assim, foi possível determinar uma relação entre a freqüência de fratura e a dimensão fractal. A simulação de um padrão de fraturas por método analítico levou em conta a direção e a freqüência de fratura e a dimensão fractal (Cantor’s Dust). Os resultados alcançados para o mapa de fraturas simulado são muito bons, principalmente pelo fato de não ter sido computado, nessa primeira versão, o comprimento das fraturas. / The fracture patterns are subject of large investigations in a number of knowledge areas. The mathematical methods research to simulate fractures patterns in geological media is also intense. This work aims to contribute for such investigations and presents the results of geological fracture pattern analysis (structural and fractal analysis) and an analytical procedure to simulate such fracture pattern. The fracture analysis was conducted in structurally homogeneous areas in Central Brazil. The fractal dimensions were computed by both Box-counting and Cantor’s Dust methods, in order to characterize each geological area. Box-counting fractal dimensions showed values in the range 1 and 2, but did not enable to evaluate fracture anisotropies, such as fracture length, frequency and orientation. On the other hand, Cantor’s Dust fractal dimensions showed values between 0 and 1, so it is able to determine fracture anisotropies, since orthogonal grid rotation defined different fractal dimensions. The structural analysis of the fracture patterns was conducted taking into account fracture directions, length and frequency. In this way, it is possible to correlate fracture frequency and Cantor’s Dust fractal dimensions. The achieved results for the fracture lineament map simulation are reasonable good, because it did not consider the fracture length according each direction.
3

Análise e simulação de padrões de fraturas geológicas

Gioveli, Izabel January 2010 (has links)
Os padrões de fratura são objeto de intensas investigações em várias áreas do conhecimento. Além disso, a busca por métodos matemáticos para simulação de mapas de fratura em meios geológicos tem sido alvo de muitas investigações. Este trabalho apresenta um estudo sobre a dimensão fractal de padrões de fraturas geológicas e a simulação de um mapa de fratura geológica através da análise fractal de áreas estruturalmente homogêneas na região Central do Brasil. As dimensões fractais são determinadas pelos métodos Box-counting e Cantor’s Dust num sistema anisotrópico de fraturas, a fim de caracterizar áreas geológicas selecionadas. A dimensão fractal obtida pelo método Box-counting possui valores entre um e dois, mas não permite analisar anisotropias de comprimento das fraturas, ou mesmo na sua distribuição espacial. A dimensão fractal obtida com o método de Cantor’s Dust, por outro lado, possui valores entre zero e um e fornece mecanismos adequados à avaliação da anisotropia das redes de fraturas geológicas. Deve-se observar, a partir dos resultados obtidos, que a dimensão fractal (Cantor’s Dust) depende das direções de fratura e que o número de interseções de fraturas aumenta com a diminuição da dimensão fractal. A dimensão fractal (Cantor’s Dust) também varia conforme a direção da rede de linhas ortogonais, indicando o caráter levemente anisotrópico dos padrões de fratura geológica sob análise. A análise estrutural dos padrões de fratura foi efetuada sobre as direções, o comprimento e a freqüência das fraturas de cada área homogênea. Assim, foi possível determinar uma relação entre a freqüência de fratura e a dimensão fractal. A simulação de um padrão de fraturas por método analítico levou em conta a direção e a freqüência de fratura e a dimensão fractal (Cantor’s Dust). Os resultados alcançados para o mapa de fraturas simulado são muito bons, principalmente pelo fato de não ter sido computado, nessa primeira versão, o comprimento das fraturas. / The fracture patterns are subject of large investigations in a number of knowledge areas. The mathematical methods research to simulate fractures patterns in geological media is also intense. This work aims to contribute for such investigations and presents the results of geological fracture pattern analysis (structural and fractal analysis) and an analytical procedure to simulate such fracture pattern. The fracture analysis was conducted in structurally homogeneous areas in Central Brazil. The fractal dimensions were computed by both Box-counting and Cantor’s Dust methods, in order to characterize each geological area. Box-counting fractal dimensions showed values in the range 1 and 2, but did not enable to evaluate fracture anisotropies, such as fracture length, frequency and orientation. On the other hand, Cantor’s Dust fractal dimensions showed values between 0 and 1, so it is able to determine fracture anisotropies, since orthogonal grid rotation defined different fractal dimensions. The structural analysis of the fracture patterns was conducted taking into account fracture directions, length and frequency. In this way, it is possible to correlate fracture frequency and Cantor’s Dust fractal dimensions. The achieved results for the fracture lineament map simulation are reasonable good, because it did not consider the fracture length according each direction.
4

Análise e simulação de padrões de fraturas geológicas

Gioveli, Izabel January 2010 (has links)
Os padrões de fratura são objeto de intensas investigações em várias áreas do conhecimento. Além disso, a busca por métodos matemáticos para simulação de mapas de fratura em meios geológicos tem sido alvo de muitas investigações. Este trabalho apresenta um estudo sobre a dimensão fractal de padrões de fraturas geológicas e a simulação de um mapa de fratura geológica através da análise fractal de áreas estruturalmente homogêneas na região Central do Brasil. As dimensões fractais são determinadas pelos métodos Box-counting e Cantor’s Dust num sistema anisotrópico de fraturas, a fim de caracterizar áreas geológicas selecionadas. A dimensão fractal obtida pelo método Box-counting possui valores entre um e dois, mas não permite analisar anisotropias de comprimento das fraturas, ou mesmo na sua distribuição espacial. A dimensão fractal obtida com o método de Cantor’s Dust, por outro lado, possui valores entre zero e um e fornece mecanismos adequados à avaliação da anisotropia das redes de fraturas geológicas. Deve-se observar, a partir dos resultados obtidos, que a dimensão fractal (Cantor’s Dust) depende das direções de fratura e que o número de interseções de fraturas aumenta com a diminuição da dimensão fractal. A dimensão fractal (Cantor’s Dust) também varia conforme a direção da rede de linhas ortogonais, indicando o caráter levemente anisotrópico dos padrões de fratura geológica sob análise. A análise estrutural dos padrões de fratura foi efetuada sobre as direções, o comprimento e a freqüência das fraturas de cada área homogênea. Assim, foi possível determinar uma relação entre a freqüência de fratura e a dimensão fractal. A simulação de um padrão de fraturas por método analítico levou em conta a direção e a freqüência de fratura e a dimensão fractal (Cantor’s Dust). Os resultados alcançados para o mapa de fraturas simulado são muito bons, principalmente pelo fato de não ter sido computado, nessa primeira versão, o comprimento das fraturas. / The fracture patterns are subject of large investigations in a number of knowledge areas. The mathematical methods research to simulate fractures patterns in geological media is also intense. This work aims to contribute for such investigations and presents the results of geological fracture pattern analysis (structural and fractal analysis) and an analytical procedure to simulate such fracture pattern. The fracture analysis was conducted in structurally homogeneous areas in Central Brazil. The fractal dimensions were computed by both Box-counting and Cantor’s Dust methods, in order to characterize each geological area. Box-counting fractal dimensions showed values in the range 1 and 2, but did not enable to evaluate fracture anisotropies, such as fracture length, frequency and orientation. On the other hand, Cantor’s Dust fractal dimensions showed values between 0 and 1, so it is able to determine fracture anisotropies, since orthogonal grid rotation defined different fractal dimensions. The structural analysis of the fracture patterns was conducted taking into account fracture directions, length and frequency. In this way, it is possible to correlate fracture frequency and Cantor’s Dust fractal dimensions. The achieved results for the fracture lineament map simulation are reasonable good, because it did not consider the fracture length according each direction.
5

Fractal Dimensions in Classical and Quantum Mechanical Open Chaotic Systems

Schönwetter, Moritz 17 January 2017 (has links) (PDF)
Fractals have long been recognized to be a characteristic feature arising from chaotic dynamics; be it in the form of strange attractors, of fractal boundaries around basins of attraction, or of fractal and multifractal distributions of asymptotic measures in open systems. In this thesis we study fractal and multifractal measure distributions in leaky Hamiltonian systems. Leaky systems are created by introducing a fully or partially transparent hole in an otherwise closed system, allowing trajectories to escape or lose some of their intensity. This dynamics results in intricate (multi)fractal distributions of the surviving trajectories. These systems are suitable models for experimental setups such as optical microcavities or microwave resonators. In this thesis we perform an improved investigation of the fractality in these systems using the concept of effective dimensions. They are defined as the dimensions far from the usually considered asymptotics of infinite evolution time $t$, infinite sample size $S$, and infinite resolution (infinitesimal box-size $varepsilon$). Yet, as we show, effective dimensions can be considered as intrinsic to the dynamics of the system. We present a detailed discussion of the behaviour of the numerically observed dimension $D_mathrm{obs}(S,t,varepsilon)$. We show that the three parameters can be expressed in terms of limiting length scales that define the parameter ranges in which $D_mathrm{obs}(S,t,varepsilon)$ is an effective dimension of the system. We provide dynamical and statistical arguments for the dependence of these scales on $S$, $t$, and $varepsilon$ in strongly chaotic systems and show that the knowledge of the scales allows us to define meaningful effective dimensions. We apply our results to three main fields. In the context of numerical algorithms to calculate dimensions, we show that our findings help to numerically find the range of box sizes leading to accurate results. We further show that they allow us to minimize the computational cost by providing estimates of the required sample-size and iteration time needed. A second application field of our results is systems exhibiting non-trivial dependencies of the effective dimension $D_mathrm{eff}$ on $t$ and $varepsilon$. We numerically explore this in weakly chaotic leaky systems. There, our findings provide insight into the dynamics of the systems, since deviations from our predictions based on strongly chaotic systems at a given parameter range are a sign that the stickiness inherent to such systems needs to be taken into account in that range. Lastly, we show that in quantum analogues of chaotic maps with a partial leak, a related effective dimension can be used to explain the numerically observed deviation from the predictions provided by the fractal Weyl law for systems with fully absorbing leaks. Here, we provide an analytical description of the expected scaling based on the classical dynamics of the system and compare it with numerical results obtained in the studied quantum maps. / Es ist seit langem bekannt, dass Fraktale eine charakteristische Begleiterscheinung chaotischer Dynamik sind. Sie treten in Form von seltsamen Attraktoren, von fraktalen Begrenzungen der Einzugsbereiche von Attraktoren oder von fraktalen und multifraktalen Verteilungen asymptotischer Maße in offenen Systemen auf. In dieser Arbeit betrachten wir fraktal und multifraktal verteilte Maße in geöffneten hamiltonschen Systemen. Geöffnete Systeme werden dadurch erzeugt, dass man ein völlig oder teilweise transparentes Loch im Phasenraum definiert, durch das Trajektorien entkommen können oder in dem sie einen Teil ihrer Intensität verlieren. Die Dynamik in solchen Systemen erzeugt komplexe (multi)fraktale Verteilungen der verbleibenden Trajektorien, beziehungsweise ihrer Intensitäten. Diese Systeme sind zur Modellierung experimenteller Aufbauten, wie zum Beispiel optischer Mikrokavitäten oder Mikrowellenresonatoren, geeignet. In dieser Arbeit führen wir eine verbesserte Untersuchung der Fraktalität in derartigen Systemen durch, die auf dem Konzept der effektiven Dimensionen beruht. Diese sind als die Dimensionen definiert, die weit weg von den üblicherweise betrachteten Limites unendlicher Iterationszeit $t$, unendlicher Stichprobengröße $S$ und unendlicher Auflösung, also infinitesimaler Boxgröße $varepsilon$ auftreten. Dennoch können effektive Dimensionen, wie wir zeigen, als der Dynamik des Systems inhärent angesehen werden. Wir führen eine detaillierte Diskussion der numerisch beobachteten Dimension $D_mathrm{obs}(S,t,varepsilon)$ durch und zeigen, dass die drei Parameter $S$, $t$ und $varepsilon$ in Form grenzwertiger Längenskalen ausgedrückt werden können, die die Parameterbereiche definieren, in denen $D_mathrm{obs}(S,t,varepsilon)$ den Wert einer effektiven Dimension des Systems annimmt. Wir beschreiben das Verhalten dieser Längenskalen in stark chaotischen Systemen als Funktionen von $S$, $t$ und $varepsilon$ anhand statistischer Überlegungen und anhand von auf der Dynamik basierenden Aussagen. Weiterhin zeigen wir, dass das Wissen um diese Längenskalen die Definition aussagekräftiger effektiver Dimensionen ermöglicht. Wir wenden unsere Ergebnisse hauptsächlich in drei Bereichen an: Im Kontext numerischer Algorithmen zur Dimensionsberechnung zeigen wir, dass unsere Ergebnisse es erlauben, diejenigen $varepsilon$-Bereiche zu finden, die zu korrekten Ergebnissen führen. Weiterhin zeigen wir, dass sie es uns erlauben, den Rechenaufwand zu minimieren, indem sie uns eine Abschätzung der benötigten Stichprobengröße und Iterationszeit ermöglichen. Ein zweiter Anwendungsbereich sind Systeme, die sich durch eine nichttriviale Abhängigkeit von $D_mathrm{eff}$ von $t$ und $varepsilon$ auszeichnen. Hier ermöglichen unsere Ergebnisse ein besseres Verständnis der Systeme, da Abweichungen von den Vorhersagen basierend auf der Annahme von starker Chaotizität ein Anzeichen dafür sind, dass im entsprechenden Parameterbereich die Eigenschaft dieser Systeme, dass Bereiche in ihrem Phasenraum Trajektorien für eine begrenzte Zeit einfangen können, relevant ist. Zuletzt zeigen wir, dass in quantenmechanischen Analoga chaotischer Abbildungen mit partiellen Öffnungen eine verwandte effektive Dimension genutzt werden kann, um die numerisch beobachteten Abweichungen vom fraktalen weyl'schen Gesetz für völlig transparente Öffnungen zu erklären. In diesem Zusammenhang zeigen wir eine analytische Beschreibung des erwarteten Skalierungsverhaltens auf, die auf der klassischen Dynamik des Systems basiert, und vergleichen sie mit numerischen Erkenntnissen, die wir über die Quantenabbildungen gewonnen haben.
6

Fractal Dimensions in Classical and Quantum Mechanical Open Chaotic Systems

Schönwetter, Moritz 17 January 2017 (has links)
Fractals have long been recognized to be a characteristic feature arising from chaotic dynamics; be it in the form of strange attractors, of fractal boundaries around basins of attraction, or of fractal and multifractal distributions of asymptotic measures in open systems. In this thesis we study fractal and multifractal measure distributions in leaky Hamiltonian systems. Leaky systems are created by introducing a fully or partially transparent hole in an otherwise closed system, allowing trajectories to escape or lose some of their intensity. This dynamics results in intricate (multi)fractal distributions of the surviving trajectories. These systems are suitable models for experimental setups such as optical microcavities or microwave resonators. In this thesis we perform an improved investigation of the fractality in these systems using the concept of effective dimensions. They are defined as the dimensions far from the usually considered asymptotics of infinite evolution time $t$, infinite sample size $S$, and infinite resolution (infinitesimal box-size $varepsilon$). Yet, as we show, effective dimensions can be considered as intrinsic to the dynamics of the system. We present a detailed discussion of the behaviour of the numerically observed dimension $D_mathrm{obs}(S,t,varepsilon)$. We show that the three parameters can be expressed in terms of limiting length scales that define the parameter ranges in which $D_mathrm{obs}(S,t,varepsilon)$ is an effective dimension of the system. We provide dynamical and statistical arguments for the dependence of these scales on $S$, $t$, and $varepsilon$ in strongly chaotic systems and show that the knowledge of the scales allows us to define meaningful effective dimensions. We apply our results to three main fields. In the context of numerical algorithms to calculate dimensions, we show that our findings help to numerically find the range of box sizes leading to accurate results. We further show that they allow us to minimize the computational cost by providing estimates of the required sample-size and iteration time needed. A second application field of our results is systems exhibiting non-trivial dependencies of the effective dimension $D_mathrm{eff}$ on $t$ and $varepsilon$. We numerically explore this in weakly chaotic leaky systems. There, our findings provide insight into the dynamics of the systems, since deviations from our predictions based on strongly chaotic systems at a given parameter range are a sign that the stickiness inherent to such systems needs to be taken into account in that range. Lastly, we show that in quantum analogues of chaotic maps with a partial leak, a related effective dimension can be used to explain the numerically observed deviation from the predictions provided by the fractal Weyl law for systems with fully absorbing leaks. Here, we provide an analytical description of the expected scaling based on the classical dynamics of the system and compare it with numerical results obtained in the studied quantum maps. / Es ist seit langem bekannt, dass Fraktale eine charakteristische Begleiterscheinung chaotischer Dynamik sind. Sie treten in Form von seltsamen Attraktoren, von fraktalen Begrenzungen der Einzugsbereiche von Attraktoren oder von fraktalen und multifraktalen Verteilungen asymptotischer Maße in offenen Systemen auf. In dieser Arbeit betrachten wir fraktal und multifraktal verteilte Maße in geöffneten hamiltonschen Systemen. Geöffnete Systeme werden dadurch erzeugt, dass man ein völlig oder teilweise transparentes Loch im Phasenraum definiert, durch das Trajektorien entkommen können oder in dem sie einen Teil ihrer Intensität verlieren. Die Dynamik in solchen Systemen erzeugt komplexe (multi)fraktale Verteilungen der verbleibenden Trajektorien, beziehungsweise ihrer Intensitäten. Diese Systeme sind zur Modellierung experimenteller Aufbauten, wie zum Beispiel optischer Mikrokavitäten oder Mikrowellenresonatoren, geeignet. In dieser Arbeit führen wir eine verbesserte Untersuchung der Fraktalität in derartigen Systemen durch, die auf dem Konzept der effektiven Dimensionen beruht. Diese sind als die Dimensionen definiert, die weit weg von den üblicherweise betrachteten Limites unendlicher Iterationszeit $t$, unendlicher Stichprobengröße $S$ und unendlicher Auflösung, also infinitesimaler Boxgröße $varepsilon$ auftreten. Dennoch können effektive Dimensionen, wie wir zeigen, als der Dynamik des Systems inhärent angesehen werden. Wir führen eine detaillierte Diskussion der numerisch beobachteten Dimension $D_mathrm{obs}(S,t,varepsilon)$ durch und zeigen, dass die drei Parameter $S$, $t$ und $varepsilon$ in Form grenzwertiger Längenskalen ausgedrückt werden können, die die Parameterbereiche definieren, in denen $D_mathrm{obs}(S,t,varepsilon)$ den Wert einer effektiven Dimension des Systems annimmt. Wir beschreiben das Verhalten dieser Längenskalen in stark chaotischen Systemen als Funktionen von $S$, $t$ und $varepsilon$ anhand statistischer Überlegungen und anhand von auf der Dynamik basierenden Aussagen. Weiterhin zeigen wir, dass das Wissen um diese Längenskalen die Definition aussagekräftiger effektiver Dimensionen ermöglicht. Wir wenden unsere Ergebnisse hauptsächlich in drei Bereichen an: Im Kontext numerischer Algorithmen zur Dimensionsberechnung zeigen wir, dass unsere Ergebnisse es erlauben, diejenigen $varepsilon$-Bereiche zu finden, die zu korrekten Ergebnissen führen. Weiterhin zeigen wir, dass sie es uns erlauben, den Rechenaufwand zu minimieren, indem sie uns eine Abschätzung der benötigten Stichprobengröße und Iterationszeit ermöglichen. Ein zweiter Anwendungsbereich sind Systeme, die sich durch eine nichttriviale Abhängigkeit von $D_mathrm{eff}$ von $t$ und $varepsilon$ auszeichnen. Hier ermöglichen unsere Ergebnisse ein besseres Verständnis der Systeme, da Abweichungen von den Vorhersagen basierend auf der Annahme von starker Chaotizität ein Anzeichen dafür sind, dass im entsprechenden Parameterbereich die Eigenschaft dieser Systeme, dass Bereiche in ihrem Phasenraum Trajektorien für eine begrenzte Zeit einfangen können, relevant ist. Zuletzt zeigen wir, dass in quantenmechanischen Analoga chaotischer Abbildungen mit partiellen Öffnungen eine verwandte effektive Dimension genutzt werden kann, um die numerisch beobachteten Abweichungen vom fraktalen weyl'schen Gesetz für völlig transparente Öffnungen zu erklären. In diesem Zusammenhang zeigen wir eine analytische Beschreibung des erwarteten Skalierungsverhaltens auf, die auf der klassischen Dynamik des Systems basiert, und vergleichen sie mit numerischen Erkenntnissen, die wir über die Quantenabbildungen gewonnen haben.
7

The interplay between physical and chemical processes in the formation of world-class orogenic gold deposits in the Eastern Goldfields Province, Western Australia

Hodkiewicz, Paul January 2003 (has links)
[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] The formation of world-class Archean orogenic gold deposits in the Eastern Goldfields Province of Western Australia was the result of a critical combination of physical and chemical processes that modified a single and widespread ore-fluid along fluid pathways and at the sites of gold deposition. Increased gold endowment in these deposits is associated with efficient regional-scale fluid focusing mechanisms and the influence of multiple ore-depositional processes at the deposit-scale. Measurement of the complexity of geologic features, as displayed in high-quality geologic maps of uniform data density, can be used to highlight areas that influence regional-scale hydrothermal fluid flow. Useful measurements of geological complexity include fractal dimensions of map patterns, density and orientation of faults and lithologic contacts, and proportions of rock types. Fractal dimensions of map patterns of lithologic contacts and faults highlight complexity gradients. Steep complexity gradients, between domains of high and low fractal dimensions within a greenstone belt, correspond to district-scale regions that have the potential to focus the flow of large volumes of hydrothermal fluid, which is critical for the formation of significant orogenic gold mineralization. Steep complexity gradients commonly occur in greenstone belts where thick sedimentary units overly more complex patterns of lithologic contacts, associated with mafic intrusive and mafic volcanic units. The sedimentary units in these areas potentially acted as seals to the hydrothermal Mineral Systems, which resulted in fluid-pressure gradients and increased fluid flow. The largest gold deposits in the Kalgoorlie Terrane and the Laverton Tectonic Zone occur at steep complexity gradients adjacent to thick sedimentary units, indicating the significance of these structural settings to gold endowment. Complexity gradients, as displayed in surface map patterns, are an indication of three-dimensional connectivity along fluid pathways, between fluid source areas and deposit locations. Systematic changes in the orientation of crustal-scale shear zones are also significant and measurable map features. The largest gold deposits along the Bardoc Tectonic Zone and Boulder-Lefroy Shear Zone, in the Eastern Goldfields Province, occur where there are counter-clockwise changes in shear zone orientation, compared to the average orientation of the shear zone along its entire length. Sinistral movement along these shear zones resulted in the formation of district-scale dilational jogs and focused hydrothermal fluid-flow at the Golden Mile, New Celebration and Victory-Defiance deposits. Faults and lithologic contacts are the dominant fluid pathways in orogenic gold Mineral Systems, and measurements of the density of faults and contacts are also a method of quantifying the complexity of geologic map patterns on high-quality maps. Significantly higher densities of pathways in areas surrounding larger gold deposits are measurable within 20- and 5-kilometer search radii around them. Large variations in the sulfur isotopic composition of ore-related pyrites in orogenic gold deposits in the Eastern Goldfields Province are the result of different golddepositional mechanisms and the in-situ oxidation of a primary ore fluid in specific structural settings. Phase separation and wall-rock carbonation are potentially the most common mechanisms of ore-fluid oxidation and gold precipitation. The influence of multiple gold-depositional mechanisms increases the potential for significant ore-fluid oxidation, and more importantly, provides an effective means of increasing gold endowment. This explains the occurrence of negative δ34S values in ore-related pyrites in some world-class orogenic gold deposits. Sulfur isotopic compositions alone cannot uniquely define potential gold endowment. However, in combination with structural, hydrothermal alteration and fluid inclusion studies that also seek to identify multiple ore-forming processes, they can be a useful indicator. The structural setting of a deposit is also a potentially important factor controlling ore-fluid oxidation and the distribution of δ34S values in ore-related pyrites. At Victory-Defiance, the occurrence of negative δ34S(py) values in gently-dipping dilational structures, compared to more positive δ34S(py) values in steeply-dipping compressional structures, is potentially associated with different gold-depositional mechanisms that developed as a result of fluid-pressure fluctuations during different stages of the fault-valve cycle. During the pre-failure stage, when fluids are discharging from faults, fluid-rock interaction is the dominant gold-depositional mechanism. Phase separation and back-mixing of modified ore-fluid components are dominant during and immediately after faulting. Under appropriate conditions, any, or all, of these three mechanisms can oxidize orogenic gold fluids and cause gold deposition. The influence of multiple gold-depositional mechanisms during fault-valve cycles at dilational jogs, where fluid pressure fluctuations are interpreted to be most severe, can potentially explain both the large gold endowment of the giant to world-class Golden Mile, New Celebration and Victory-Defiance deposits along the Boulder-Lefroy Shear Zone, and the presence of gold-related pyrites with negative δ34S values in these deposits. This study highlights the interplay that exists between physical and chemical processes in orogenic gold Mineral Systems, during the transport of ore fluids in pathways from original fluid reservoirs to deposit sites. Potentially, a single and widespread orogenic ore-fluid could become oxidized, and lead to the formation of ore-related sulfides with variable sulfur isotopic compositions, depending on the nature and orientation of major fluid pathways, the nature of wall-rocks through which it circulates, and the precise ore-depositional processes that develop during fault-valve cycles.
8

Identification of Fractal Dimensions from a Dynamical Analogy / Identificação de dimensões fractais a partir de uma analogia dinâmica

Marcelo Miranda Barros 23 March 2007 (has links)
Several areas of knowledge use fractal geometry to help to understand natural objects and phenomena. Irregular self-similar - in which parts resemble the whole - objects may be better understood through fractal dimensions which provide how a property varies with resolution or scale. We present a new approach to calculate fractal dimensions that, instead of the frequently used methods based on covering, seeks geometry information from physical characteristics. Here, we treat the element of a fractal sequence as structures. Imposing constraints on the structures, we build simple harmonic oscillators. The variation of the period of these oscillators with respect to a determined measure of length provides a fractal dimension. This techinique was tested for a family of continuous self-similar plane curves, including the classical Koch triadic. We show that this dynamical dimension may be related to Hausdorff-Besicovitch dimension. With random geometry, the techinique besides providing a fractal dimension, identifies randomness. A new kind of fractal is also presented. The ideia is to use more than one generator in the generation process of a fractal to obtain mixed fractals. / Diversas áreas do conhecimento têm utilizado a geometria fractal para melhor entender muitos objetos e fenômenos naturais. Objetos irregulares com padrão auto-similar onde as partes se assemelham ao todo podem ser melhor compreendidos através de dimensões fractais que fornecem como o valor de uma propriedade varia dependendo da resolução, ou escala, em que o objeto é observado ou medido. Apresentamos uma nova abordagem para calcular dimensões fractais através de características físicas. Neste trabalho busca-se uma caracterização da dinâmica de estruturas lineares com geometria fractal. Trata-se os elementos de uma sequência geradora de um fractal como estruturas. Osciladores harmônicos simples são construídos com tais estruturas. A variação do período de vibração desses osciladores com uma determinada medida de comprimento nos fornece uma dimensão fractal. A técnica foi testada para a família de curvas contínuas e auto-similares no plano, onde está incluída a clássica triádica de Koch. Mostramos que essa dimensão dinâmica pode ser relacionada à dimensão de Hausdorff-Besicovitch. Com geometria aleatória, a técnica além de fornecer a dimensão fractal, identifica a aleatoriedade. Um novo tipo de fractal é apresentado. A idéia é usar mais de um gerador no processo de geração de um fractal para obter os fractais mistos.
9

MULTISCALING ANALYSIS OF FLUIDIC SYSTEMS: MIXING AND MICROSTRUCTURE CHARACTERIZATION

Camesasca, Marco 07 April 2006 (has links)
No description available.
10

Identificação de dimensões fractais a partir de uma analogia dinâmica / Identification of Fractal Dimensions from a Dynamical Analogy

Barros, Marcelo Miranda 23 March 2007 (has links)
Made available in DSpace on 2015-03-04T18:50:54Z (GMT). No. of bitstreams: 1 Dissertacao Marcelo Barros.pdf: 906132 bytes, checksum: 67f089fdd05da5a2f2ab6d807fbbf51b (MD5) Previous issue date: 2007-03-23 / Several areas of knowledge use fractal geometry to help to understand natural objects and phenomena. Irregular self-similar - in which parts resemble the whole - objects may be better understood through fractal dimensions which provide how a property varies with resolution or scale. We present a new approach to calculate fractal dimensions that, instead of the frequently used methods based on covering, seeks geometry information from physical characteristics. Here, we treat the element of a fractal sequence as structures. Imposing constraints on the structures, we build simple harmonic oscillators. The variation of the period of these oscillators with respect to a determined measure of length provides a fractal dimension. This techinique was tested for a family of continuous self-similar plane curves, including the classical Koch triadic. We show that this dynamical dimension may be related to Hausdorff-Besicovitch dimension. With random geometry, the techinique besides providing a fractal dimension, identifies randomness. A new kind of fractal is also presented. The ideia is to use more than one generator in the generation process of a fractal to obtain mixed fractals. / Diversas áreas do conhecimento têm utilizado a geometria fractal para melhor entender muitos objetos e fenômenos naturais. Objetos irregulares com padrão auto-similar onde as partes se assemelham ao todo podem ser melhor compreendidos através de dimensões fractais que fornecem como o valor de uma propriedade varia dependendo da resolução, ou escala, em que o objeto é observado ou medido. Apresentamos uma nova abordagem para calcular dimensões fractais através de características físicas. Neste trabalho busca-se uma caracterização da dinâmica de estruturas lineares com geometria fractal. Trata-se os elementos de uma sequência geradora de um fractal como estruturas. Osciladores harmônicos simples são construídos com tais estruturas. A variação do período de vibração desses osciladores com uma determinada medida de comprimento nos fornece uma dimensão fractal. A técnica foi testada para a família de curvas contínuas e auto-similares no plano, onde está incluída a clássica triádica de Koch. Mostramos que essa dimensão dinâmica pode ser relacionada à dimensão de Hausdorff-Besicovitch. Com geometria aleatória, a técnica além de fornecer a dimensão fractal, identifica a aleatoriedade. Um novo tipo de fractal é apresentado. A idéia é usar mais de um gerador no processo de geração de um fractal para obter os fractais mistos.

Page generated in 0.1318 seconds