Dissertations / Theses on the topic 'Scattering coefficient'
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Fröba, Andreas P., Cristina Botero, Heiko Kremer, and Alfred Leipertz. "Mutual diffusion coefficient in fluids by dynamic light scattering." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196269.
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Fröba, Andreas P., Cristina Botero, Heiko Kremer, and Alfred Leipertz. "Mutual diffusion coefficient in fluids by dynamic light scattering." Diffusion fundamentals 2 (2005) 70, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14404.
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Baker, Stephen. "Optimal determination of the optical coefficients from scattering media." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268794.
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Davies, Joshua. "NNNLO and all-order corrections to splitting and coefficient functions in deep-inelastic scattering." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003745/.
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This thesis describes several calculations of quantities describing the deep-inelastic scattering (DIS) of leptons and hadrons, within the framework of massless perturbative quantum chromodynamics. The third order (NNNLO) contributions to the coefficient functions C⁻ 2,ns, C⁻ L,ns and C⁻ 3,ns, which describe charged-current (W±-exchange) DIS in the linear combination W⁺-W⁻ are presented. Complementing existing results for the W⁺+W⁻ combination, these new results complete the third-order description of charged-current DIS. The results are presented both as compact parametrizations and exact expressions. The corrections are found to be small for experimentally relevant values of the Bjorken-x variable. The behaviour of the DIS structure functions in the small-x limit is considered. By finding a suitable functional form with which to describe them, it is possible to use the results of existing fixed-order perturbative calculations to resum the leading small-x double logarithms of the coefficient functions and splitting functions to all orders in the strong coupling constant αs. All-order descriptions of the leading three double logarithms are discussed and presented for both coefficient functions and splitting functions. Finally, the results of recent advances in the fourth-order computation of the Mellin moments of structure functions are used to reconstruct expressions for the general Mellin-N dependence of the large-nf parts of the fourth-order contributions to the splitting functions. The software package FORCER is able to compute a sufficient number of Mellin moments to determine the N dependence of the n²f terms of the non-singlet splitting functions, and the n³f terms of the singlet splitting functions. The resulting expressions are in agreement with, and extend, various existing computations found in the literature.
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Aslan, Gokhan. "Cepstral Deconvolution Method For Measurement Of Absorption And Scattering Coefficients Of Materials." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608021/index.pdf.
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Several methods are developed to measure absorption and scattering coefficients of materials. In this study, a new method based on cepstral deconvolution technique is proposed. A reverberation room method standardized recently by ISO (ISO 17497-1) is taken as the reference for measurements. Several measurements were conducted in a physically scaled reverberation room and results are evaluated according to these two methods, namely, the method given
in the standard and cepstral deconvolution method. Two methods differ from each other in the estimation of specular parts of room impulse responses essential for determination of scattering coefficients. In the standard method, specular part
is found by synchronous averaging of impulse responses. However, cepstral deconvolution method utilizes cepstral analysis to obtain the specular part instead of averaging. Results obtained by both of these two approaches are compared for five different test materials. Both of the methods gave almost same values for absorption coefficients. On the other hand, lower scattering coefficient values
have been obtained for cepstral deconvolution with respect to the ISO method.
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O'Bree, Terry Adam, and s9907681@student rmit edu au. "Investigations of light scattering by Australian natural waters for remote sensing applications." RMIT University. Applied Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080110.140055.
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Remote sensing is the collection of information about an object from a distance without physically being in contact with it. The type of remote sensing of interest here is in the form of digital images of water bodies acquired by satellite. The advantage over traditional sampling techniques is that data can be gathered quickly over large ranges, and be available for immediate analysis. Remote sensing is a powerful technique for the monitoring of water bodies. To interpret the remotely sensed data, however, knowledge of the optical properties of the water constituents is needed. One of the most important of these is the volume scattering function, which describes the angular distribution of light scattered by a sample. This thesis presents the first measurements of volume scattering functions for Australian waters. Measurements were made on around 40 different samples taken from several locations in the Gippsland lakes and the Great Barrier Reef. The measurements were made by modifying an existing static light scattering spectrometer in order to accurately measure the volume scattering functions. The development of the apparatus, its calibration and automation, and the application of a complex series of post-acquisition data corrections, are all discussed. In order to extrapolate the data over the full angular range, the data was analysed using theoretical curves calculated for multi-modal size distributions using Mie light scattering theory applied to each data set. From the Mie fits the scattering and backscattering coefficients were calculated. These were compared with scattering coefficients measured using in situ sensors ac-9 and Hydroscat-6, and with values from the literature. The effect of chlorophyll a concentrations on the scattering coefficients was examined, and a brief investigation of the polarisation properties of the samples was also undertaken. Finally the angular effects on the relationship between the backscattering coefficient and the volume scattering function were investigated. This is important as in situ backscattering sensors often assume that measuring at a single fixed-angle is a good approximation for calculating the backscattering coefficient. This assumption is tested, and the optimal measurement angle determined.
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Botero, Cristina, Heiko Kremer, Andreas P. Fröba, and Alfred Leipertz. "Particle diffusion coefficient and dynamic viscosity in non-ideal liquid mixtures by dynamic light scattering." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196233.
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Botero, Cristina, Heiko Kremer, Andreas P. Fröba, and Alfred Leipertz. "Particle diffusion coefficient and dynamic viscosity in non-ideal liquid mixtures by dynamic light scattering." Diffusion fundamentals 2 (2005) 67, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14401.
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Neukermans, Griet. "Les particules en suspension dans les eaux côtières turbides : estimation par mesures optique in situ et depuis l'espace." Thesis, Littoral, 2012. http://www.theses.fr/2012DUNK0406/document.
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Les particules en suspension dans l'eau de mer incluent les sédiments, le phytoplancton, le zooplancton, les bactéries, les virus et des détritus. Ces particules sont communément appelés matière en suspension (MES). Dans les eaux côtières, la MES peut parcourir de longues distances et être transportée verticalement à travers la colonne d'eau sous l'effet des vents et des marées favorisant les processus d'advection et de resuspension. Ceci implique une large variabilité spatio-temporelle de MES et quasiment impossible à reconstituer à travers les mesures traditionnelles des concentrations de MES [MES], par filtration de l'eau de mer à bord de bateaux. La [MES] peut être obtenue à partir de capteurs optiques enregistrant la diffusion et déployés soit de manière in-situ, soit à partir d'un satellite dans l'espace. Depuis la fin des années 70, par exemple, les satellites "couleur de l'eau" permettent d'établir des cartes de [MES] globales. La fréquence d'une image par jour pour la mer di Nord de ces capteurs polaires représente un obstacle non négligeable pour l'étude de variabilité de la [MES] dans les eaux côtières où la marée et les vents engendrent des variations rapides au cours de la journée. Cette limitation est d'autant plus importante pour les régions avec une couverture nuageuse fréquente. Les méthodes in-situ à partir d'un navire autonome ou d'une plateforme amarrée permettent d'enregistrer des données en continu mais leur couverture spatiale reste néanmoins limitée. Ce travail a pour objectif de mettre en avant les techniques de mesures in-situ et satellite de la [MES] en se concentrant principalement sur deux points. Premièrement, d'acquérir une meilleure connaissance de la variabilité de la relation entre la [MES] et la lumière diffuse, et deuxièmement, d'établir des cartes de [MES] dans la mer du Nord avec le capteur géostationnaire météorologique Européen (SEVIRI) qui donne des images chaque 15 minutes.La variabilité de la relation entre la [MES] et la lumière diffuse est étudiée à l'aide d'une banque de données in-situ. Nous démontrons que la [MES] est le mieux estimée à partir des mesures dans l'intervalle rouge du spectre de lumière rétro-diffuse. Par ailleurs, la relation entre la [MES] et la rétrodiffusion est gouvernée par la composition organique/inorganique des particules, ce qui représente des possibilités d'amélioration pour les algorithmes d'estimation de [MES] à partir de la couleur de l'eau. Nous démontrons aussi qu'avec SEVIRI il est possible d'estimer la [MES], la turbidité et le coefficient d'atténuation, deux variables étroitement liées à la [MES], avec généralement une bonne précision. Bien qu'il y ait d'importantes incertitudes dans les eaux claires, cette réussite est remarquable pour un capteur météorologique initialement conçu pour le suivi des nuages et des masses glaciaires, cibles beaucoup plus brillantes que la mer! Ce travail démontre pour la première fois que la variabilité de la [MES] à l'échelle temporelle des marées dans les eaux côtières au sud de la mer du Nord peut être capturée et mesurée par le biais de la télédétection de la couleur de l'eau ; ce qui ouvre des opportunités pour le monitoring de la turbidité et pour la modélisation des écosystèmes. Le premier capteur géostationnaire couleur de l'eau a été lancé en juin 2012, donnant des images multispectrale des eaux coréennes chaque heure. D'autres capteurs vont probablement suivre dans l'avenir, couvrant le reste des eaux du globe. Ce travail nous permet donc de préparer, de façon optimale, l'arrivée de ces capteurs qui vont révolutionner l'océanographie optiqueParticles suspended in seawater include sediments, phytoplankton, zooplankton, bacteria, viruses, and detritus, and are collectively referred to as suspended particulate matter, SPM. In coastal waters, SPM is transported over long distances and in the water column by biological, tide or wind-driven advection and resuspension processes, thus varying strongly in time and space. These strong dynamics challenge the traditional measurement of the concentration of SPM, [SPM], through filtration of seawater sampled from ships. Estimation of [SPM] from sensors recording optical scattering allows to cover larger temporal or spatial scales. So called ocean colour satelittes, for example, have been used for the mapping of [SPM] on a global scale since the late 1970s. These polar-orbiting satellites typically provide one image per day forthe North Sea area. However, the sampling frequency of these satellites is a serious limitation in coastal waters where [SPM] changes rapidly during the day due to tides and winds.Optical instruments installed on moored platforms or on under-water vehicles can be operated continuously, but their spatial coverage is limited. This work aims to advance in situ and space-based optical techniques for [SPM] retrieval by investigating the natural variability in the relationship between [SPM] and light scattering by particles and by investigating whether the European geostationary meteorological SEVIRI sensor, which provides imagery every 15 minutes, can be used for the mapping of [SPM] in the southern North Sea. Based on an extensive in situ dataset, we show that [SPM] is best estimated from red light scattered in the back directions (backscattering). Moreover, the relationship between [SPM]] and particulate backscattering is driven by the organic/inorganic composition of suspended particles, offering opportunities to improve [SPM] retrieval algorithms. We also show that SEVIRI successfully retrieves [SPM] and related parameters such as turbidity and the vertical light attenuation coefficient in turbid waters. Even though uncertainties are considerable in clear waters, this is a remarkable result for a meteorological sensor designed to monitor clouds and ice, much brighter targets than the sea! On cloud free days, tidal variability of [SPM] can now be resolved by remote sensing for the first time, offering new opportunities for monitoring of turbidity and ecosystem modelling. In June 2010 the first geostationary ocean colour sensor was launched into space which provides hourly multispectral imagery of Korean waters. Other geostationary ocean colour sensors are likely to become operational in the (near?) future over the rest of the world's sea. This work allows us to maximally prepare for the coming of geostationary ocean colour satellites, which are expected to revolutionize optical oceanography
De in zeewater aanwezige zwevende materie zoals sedimenten, fytoplankton, zooplankton, bacteriën, virussen en detritus, worden collectief "suspended particulate matter" (SPM) genoemd. In kustwateren worden deze deeltjes over lange afstanden en in de waterkolom getransporteerd door biologische processen of wind- of getijdenwerking, waardoor SPM sterk varieert in ruimte en tijd. Door deze sterke dynamiek wordt de traditionele bemonstering van de concentratie van SPM, [SPM], door middel van filtratie van zeewaterstalen aan boord van schepen ontoereikend. Optische technieken die gebruik maken van de lichtverstriioongseigenschappen van SPM bieden een gebieds- of tijdsdekkend alternatief. Zogenaamde "ocean colour" satellieten bijvoorbeeld leveren beelden van o.a. [SPM] aan het zeeoppervlak op globale schaal sinds eind 1970, met een frequantie van één beeld per dag voor de Noordzee. Deze frequentie is echter onvoldoende in onze kustwateren waar [SPM] drastisch kan veranderen in enkele uren tijd. Optische instrumenten aan boord vann schepen of op onderwatervoertuigen kunnen continu meten, maar de gebiedsdekking is deperkt. Dit werk heeft tot doel de lichtverstriioongseigenschappen van SPM te karakterizeren en te onderzoeken of de Europese geostationaire weersatelliet, die elk kwartier een beeld geeft, kan worden gebruikt voor de kartering van [SPM] in de zuidelijke Noordzee. Op basis van een grote dataset van in situ metingen tonen wij aan dat [SPM] het nauwkeurigst kan worden bepaald door de meting van de verstrooiing van rood licht in achterwaartse richtingen (terugverstrooiing). Bovendien blijkt de relatie tussen [SPM] en terugverstrooiing afhankelijk van de organische-anorganische samenstelling van zwenvende stof, wat mogelijkhenden biedt tot het verfijnen van teledetectiealgoritmen voor [SPM]. Voorts tonen woj aan dat de Europese weersatelliet, SEVIRI, successvol kan worden aangewend voor de kartering van [SPM] en gerelateerde parameters zoals troebelheid en lichtdemping in de waterkolom. Hoewel met grote meetonzekerheid in klaar water toch een opmerkelijk resultaat voor een sensor die ontworpen werd voor detectie van wolken en ijs! Op wolkenvrije dagen wordt hierdoor de getijdendynamiek van [SPM] in de zuidelijke Noordzee voor het eerst detecteerbaar vanuit de ruimte, wat nieuwe mogelijkheden biedt voor de monitoring van waterkwaliteit en verbetering van ecosysteellodellen. Sinds juni 2010 is de eerste geostationaire ocean colour satelliet een feit : elk uur een multispectraal beeld van Koreaanse wateren. Vermoedelijk zullen er in de (nabije?) toekomst meer volgen over Europa en Amerika. Dit werk laat toe ons maximaal voor te bereiden op te komst van zo'n satellieten, waarvan verwacht wordt dat zij een nieuwe revolutie in optische oceanografie zullen ontketenen
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Синашенко, Оксана Володимирівна, Оксана Владимировна Синашенко, Oksana Volodymyrivna Synashenko, Зінаїда Миколаївна Макуха, Зинаида Николаевна Макуха, Zinaida Mykolaivna Makukha, Іван Юхимович Проценко, Иван Ефимович Проценко, and Ivan Yukhymovych Protsenko. "The Influence of Electrons Scattering at Grain Boundary and at Surface on Resistivity and Thermal Coefficient of Resistance of Nanocrystalline Silver Films." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34900.
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The paper describes the method of separation of the share of both surface and grain boundary electron
scattering on resistance and thermal coefficient of resistance (TCR). The calculation of ρd, βd and gb, βgb
values, which correspond to the surface and grain boundary electron scattering respectively, and their
comparative analysis were done based on experimental data of thermal and size dependence of specific resistance
(ρ) and TCR (β) for nanocrystalline silver films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34900
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Musser, Joseph Alan. "Novel instrumentation for a scattering independent measurement of the absorption coefficient of natural waters, and a new diffuse reflector for spectroscopic instrumentation and close cavity coupling." Diss., Texas A&M University, 2006. http://hdl.handle.net/1969.1/4736.
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We report results for the development of a flow-through integrated cavity absorption meter (ICAM.) Absorption measurements have been made with 2% or less change in the signal in the presence of up to 10 m-1 of scattering in the medium. The operating range of the ICAM ranges from 0.004 m-1 to over 40 m-1 of absorption. This range allows one to use a single instrument to measure the absorption from sediment laden rivers out to the cleanest of ocean waters. Further, the ICAM signal has been shown to be independent of the flow rate and turbulence in the medium. In addition we report the development of a diffuse reflector which, to our best knowledge, has the highest measured diffuse reflectivity of 0.998 at 532 nm and 0.996 at 266 nm. We also show that the average distance a photon travels between successive reflections in an integrating cavity of arbitrary shape is four times the volume divided by the surface area, 4 V/S. Further, for a cavity which is formed by planes tangent to an inscribed sphere and which maintains a homogeneous and isotropic field, the average distance traveled by a photon between successive reflections is equal to 4 V/S of the inscribed sphere. Thus, each cavity has the same ratio of V/S as the inscribed sphere. These advances lead to an increase in the sensitivity of absorption spectroscopy. The sensitivity approaches that of cavity ring down spectroscopy (CARS), without the adverse scattering effects traditionally associated with CARS.
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Gandhi, Shikha. "Investigation Of The Effect Of Low Molecular Weight Peg On Lysozyme Interactions In Solution Using Composition Gradient Static Light Scattering." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204599050.
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Kang, Yuhong. "Calculations and Measurements of Raman Gain Coefficients of Different Fiber Types." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/30878.
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Fiber Raman amplification using the transmission line is a promising technology to increase the repeater distance as well as the capacity of the communication systems. Because of the growing importance of fiber Raman amplification, it is desired to predict the magnitude and shape of the Raman gain spectrum from the doping level and refractive index profiles of different fiber designs.
This thesis develops a method to predict the Raman gain coefficients and spectra for a pure silica core fiber and two different types of GeO2-doped silica fibers given their index profiles. An essential feature of the model is the inclusion of the variation in Raman gain coefficient over the mode field due to the variation in the Ge concentration across the fiber core. The calculated Raman gain coefficients were compared with measurements of the peak Raman gain on a step-index GeO2-doped fiber and with published measurements from various sources. Agreement between the calculated and measured peak gain for the step-index fiber was excellent. There was qualitative agreement with published measurements but there were significant differences between the calculated and published gain coefficients, which are not understood.
Part of the work sought a way of predicting Raman gain coefficients from a standard gain curve given only the fiber type and the effective area. This approach appears promising for moderately-doped fibers with the proper choice of effective area.Master of Science
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Nwanosike, Quinta M. "Effect of divalent cations and solubilizers in apoferritin and gamma D-crystallin solutions nucleation, crystallization and light scattering studies /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31736.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Ronald Rousseau; Committee Co-Chair: Athanassios Sambanis; Committee Member: Amyn Teja; Committee Member: Athanasios Nenes; Committee Member: Ingeborg Schmidt-Krey. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Böhme, Christiane. "Decay rates and scattering states for wave models with time-dependent potential." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-70939.
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Viele Problemstellungen der Naturwissenschaften führen zur Betrachtung von nichtlinearen Wellengleichungen. Dabei ist von großem Interesse, ob zu vorgegebenen kleinen Daten Lösungen eindeutig existieren und ob diese stetig von den Daten abhängen. Hilfsmittel für diese Probleme sind Aussagen über lineare Wellengleichungen. In der vorliegenden Arbeit werden lineare Klein-Gordon Gleichungen, also Wellengleichungen mit Potentialterm, mit zeitabhängiger Masse bzgl. des Verhaltens ihrer Lösungen untersucht. Von speziellem Interesse sind Resultate mit Bezug auf verallgemeinerte Energieerhaltung und sogenannte Lp – Lq decay-Abschätzungen. Aus der Arbeit geht hervor, dass man eine Klassifizierung für Gleichungen mit fallendem Masseterm finden kann. Für Gleichungen vom Wellentyp ist der Einfluss des Potentialterms gering und die Lösungen verhalten sich wie Lösungen der Wellengleichung. Dem gegenüber stehen Gleichungen vom Klein-Gordon-Typ mit erkennbarem Einfluss des Masseterms. Ausgangspunkt für die Klassifizierung ist das kritische Verhalten der Lösungen einer skaleninvarianten Gleichung mit speziellem Masseterm.
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Bartling, Karsten. "Apoferritin Crystallization in relation to Eye Cataract." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14111.
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Protein crystallization is significant in both biotechnology and biomedical applications. In biotechnology, crystallization is essential for determining the structure of both native and synthesized therapeutically important proteins. It can also be used as a final purification step and as a stable form for protein storage. With regard to biomedical systems, protein crystallization appears to be involved in the development and manifestation of certain human diseases. In particular, there exists evidence that L-rich ferritin crystals are involved in Hereditary Hyperferritinemia Cataract Syndrome (HHCS).
In the current research a microbatch crystallization apparatus has been introduced that enables (1) multiple batch crystallization experiments at various temperatures and solution conditions in parallel and (2) quantitative monitoring of crystal growth without disturbing the progress of an experiment for observation. The primary application of the apparatus is, but not limited to, screening of protein crystallization conditions, although the system can also be used for other macromolecular and small-molecule crystallization experiments.
Multiwell microbatch experiments demonstrated the dependence of apoferritin crystal growth kinetics and final crystal size on temperature and cadmium concentration. Although the solubility of apoferritin might be independent of temperature, the results of this study show that the crystal growth kinetics are affected by temperature, profoundly under some conditions.
For apoferritin under near physiological conditions the solution thermodynamics in the form of the second virial coefficient have proofed to be a valuable predictor for the crystallization outcome. Furthermore, the significance of the elevated level of some divalent cations in cataractous lenses has been studied both in dilute solutions and under crystallization conditions and cadmium seems to be sole menace in apoferritin condensation.
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Liu, Yajing. "Measurement of tissue optical properties during mechanical compression using swept source optical coherence tomography." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32395.
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Laser-based photo-thermal therapies can provide minimally-invasive treatment of cancers. Their effectiveness is limited by light penetration depth in tissue due to its highly scattering properties. The highly disordered refractive index distribution in tissue leads to multiple-scattering of incident light. It has been hypothesized that mechanical compression has a great potential to enhance the capabilities of laser therapy by inducing localized water transport, decreasing the refractive index mismatch, and decreasing the scattering coefficient of tissue. To better understand this process, we investigated the refractive index change of ex-vivo dog skin during mechanical compression using a swept-source optical coherence tomography (OCT) device built in our lab. The Lorentz-Lorenz rule of mixtures was applied to evaluate the water and protein weight fraction of tissue simultaneously. Results show that the refractive index of skin increased from 1.38 to 1.52 during compression and water content decreased about 60%-70% when the skin sample was compressed by 70%.
In addition, we conducted compression experiments on human finger, palm, back of hand, and front of forearm in vivo. OCT images of these skin sites before and after compression by 1 minute were compared. Optical thickness of epidermis and light penetration depth in the dermis were measured. The extended Huygens-Fresnel model was applied to measure the scattering coefficient μs of skin specimens. μs of skin was measured to be about 10-17 mm-1 before compression and decreased 60%-80% after compression, which increases the averaged light intensity by 2-7 dB and almost doubles light penetration depth in dermis. It is quite significant in laser therapies especially for treating epithelia cancers which originate at 1-2 mm beneath the tissue surface.
In the OCT imaging of skin dehydration experiment, we conclude that dehydration is an important mechanism of mechanical clearing.Master of Science
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Geraldelli, Wender. "Desenvolvimento e aplicação de um sistema de raios X dispersivo em energia para determinação do coeficiente de atenuação linear e do perfil de espalhamento de neoplasias mamárias." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-22072013-105636/.
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As propriedades de espalhamento de raios X e atenuação de tecidos mamários normais (adiposo e fibroglandular), neoplásicos (benigno e maligno) e vários materiais tecido-equivalente (nylon, poliacetato, polimetilmetacrilato (PMMA), água, músculo-equivalente, osso-equivalente e adiposo-equivalente) foram determinados usando um sistema de raios X dispersivo em energia (SRXDE). O SRXDE consistiu de um tubo de raios X com anodo de tungstênio operando a 60kVp, um goniômetro e dois detectores: um detector de telureto de cádmio (CdTe), posicionado a 7 graus com relação ao feixe incidente usado para detectar a distribuição em energia dos fótons espalhados (numa faixa de momento transferido de 0,5nm-1 - 3,5nm-1) e um detector de silício (Silicon Drift Detector, SDD), posicionado a zero graus e usado para detectar a distribuição em energia do feixe transmitido (com amostra) ou do feixe incidente (sem amostra). A distribuição espectral foi processada para se obter o perfil de espalhamento e o coeficiente de atenuação linear de 100 amostras de tecidos mamários (59 normal, 30 maligno e 11 benigno). Este sistema foi, também, aplicado ao estudo de regiões de transição entre tecidos com diferentes composições. Os resultados encontrados neste trabalho mostram que os tecidos mamários podem ser caracterizados através de suas propriedades de atenuação e espalhamento. Perfis de espalhamento neoplásico apresentam formato do pico principal significativamente diferente na faixa de momento transferido de 0,8nm-1 - 2,0nm-1, aos tecidos normais. Especificamente, o tecido adiposo apresentou um perfil de espalhamento muito diferente (pico principal em 1,12nm-1 e LMA de 0,33nm-1) quando comparado com tecidos neoplásico maligno e benigno e normal fibroglandular (pico principal em torno de 1,54nm-1 e LMA em torno de 0,73nm-1). O coeficiente de atenuação linear observado para os tecidos maligno, benigno e fibroglandular são muito similares e mostraram diferenças menores que 8% para energias entre 10 e 35keV. Entretanto, o tecido adiposo apresentou diferenças significativas com relação aos outros tecidos em toda faixa de energia (diferenças de até 40% foram observadas). Os resultados obtidos da varredura espacial das amostras heterogêneas mostram que o sistema desenvolvido permite o estudo de regiões de transição entre tecidos com diferentes composições. Finalmente, nossos resultados foram comparados com dados experimentais previamente publicados na literatura, mostrando boa concordância dentro das incertezas estatísticas.The X-ray scattering and attenuation properties for normal (adipose and glandular) and neoplastic (benign and malignant) breast tissues and several tissue-equivalent materials (nylon, polyacetate, polymethylmethacrylate (PMMA), water, muscle-equivalent, bone-equivalent and adipose-equivalent) were determined using an energy dispersive X-ray system (EDXS). The EDXS consisted of a tungsten anode X-ray tube operating at 60kVp, a goniometer, and two detectors: a Cadmium Telluride (CdTe) detector, positioned at 7 degrees with relation to the incident beam used for detecting the energy distribution of scattered photons (over the momentum transfer range of 0,5nm-1- 3,5nm-1) and a Silicon Drift Detector (SSD), positioned at zero degree used for detecting the energy distribution of the transmitted beam (with the sample) or the incident beam (without the sample). The spectra distributions were processed to obtaine the scattering profile and the linear attenuation coefficient of 100 samples of breast tissues (59 normal, 30 malignant and 11 benign). This system was also applied to the study of the transition regions between tissues with different composition. The results found in this work show that breast tissues may be characterized through their attenuation and scattering properties. Neoplastic scattering profiles presented format and the main peak position significantly different in the range of momentum transfer from 0,8nm-1- 2,0nm-1, to normal tissues. Specifically, adipose tissue presented a very different scattering profile (main peak at 1,12nm-1and FWHM of 0,33nm-1) when compared with malignant, benign and also normal glandular tissues (main peak around 1,54nm-1and FWHM about of 0,73nm-1). The linear attenuation coefficient observed for malignant, benign and normal glandular tissues were quite similar and showed differences smaller than 8% for energies between 10 and 35keV. However, adipose tissue presented significant differences from the others tissues type in all energy range (differences up to 40% were observed). The results of the spatial scan of heterogeneous samples show that the developed system allows the study of transition regions between tissues with different composition. Finally, our results were compared with previous experimental data showing a good agreement within the experimental uncertainties
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Lehtonen, Lauri Kalevi. "Elucidating the nature of bonding in mechanical pulps." Diss., Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-11252004-163945/.
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Thesis (Ph. D.)--Institute of Paper Science and Technology, Georgia Institute of Technology, 2005.Alan Rudie, Committee Member ; Derek Page, Committee Member ; Douglas Coffin, Committee Member ; Kari Ebeling, Committee Member ; Timothy Patterson, Committee Member. Includes bibliographical references (p. 222-231).
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Kefi, Monia. "Coefficients d'attenuation et facteurs de diffusion atomique des elements 46 a 54 dans leur region k." Paris 6, 1988. http://www.theses.fr/1988PA066326.
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Mesure des coefficients d'attenuation des elements de numero atomique 46 a 54 dans le domaine 15 a 45 kev. Determination des parametres de la loi de variation empirique du coefficient d'attenuation en fonction de la longueur d'onde du rayonnement. Determination des facteurs de diffusion anomale vers l'avant, en utilisant la relation de dispersion
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Burda, Jan. "Návrh a měření parametrů akustických difúzních prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377009.
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This work focuses on the issue of acoustic diffusers. The introductory chapter describes the necessary theory of the sound distribution through enclosed space. Acoustic fields are also described. A description of the different diffusion element types and theirs design methods follows. It focuses mainly on design, which uses pseudo-random mathematical sequences. The aim of the work is to produce several types of acoustic diffusors and to verify their diffusion properties by means of measurements. The work uses the AFMG Reflex to simulate the diffusion properties of the proposed elements. Further, the thesis contains a description of the diffusion properties measurement process by the boundary plane method and the process of evaluating the measured data using the Matlab program.
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Borsali, Redouane. "Etude theorique du comportement dynamique des melanges ternaires de polymere en solution : etude experimentale par spectroscopie rayleigh quasi-elastique." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13138.
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L'etude d'un melange ternaire de polymeres en solution semidiluee presente deux modes de relaxation. Mise en evidence par diffusion de lumiere quasi-elastique de deux processus de diffusion: le premier, lent, correspond au mouvement relatif des deux polymeres; le second, rapide, correspond au mouvement cooperatif du reseau physique forme par les deux polymeres
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Mariaud, Christian. "Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX030/document.
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En astronomie gamma, les systèmes binaires sont des objets stellaires impliquant une étoile massive et un objet compact, le plus léger des deux en orbite autour de l’autre. Ils émettent de façon régulière à haute et très haute énergie (E > 100 GeV) et peuvent être détectés par le réseau de télescopes H.E.S.S.. Malgré leur faible nombre, ils présentent une grande diversité de comportement et sont caractérisés par une modulation de flux dépendant de la position de l’objet compact. 2 systèmes binaires sont étudiés : LS 5039 et PSR B1259–63, en effet un jeu de données conséquent est disponible puisque ces sources sont observées maintenant depuis plus de 10 ans. En 2012, le cinquième télescope de plus grande taille a commencé ses observations et permet ainsi de faire la connexion avec le domaine du GeV.Une modélisation de ces deux systèmes binaires dans le cas d’une diffusion anisotrope inverse Compton dans le régime de Klein–Nishina sera aussi proposée avec une prise en compte du disque circumstellaire pour PSR B1259¡63. Les données recueillies lors d’une observation peuvent être détériorées par une atmosphère dégradée, affectant ainsi le flux de photons ° collectés. Un coefficient traduisant la qualité de l’atmosphère est donc nécessaire. De plus les gerbes peuvent être déformées à cause de laprésence du champ magnétique terrestre, les études de ces phénomènes sont donc nécessaires pour essayer de corriger ces effetsBinary systems in gamma astronomy are stellar objects involving a massive star with a compact object, the lightest in orbit around the other. They emit regularly at high energy and very high energy (E > 100 GeV) for detection by H.E.S.S. telescopes. Despite their low relative number, they are all characterized by a modulation of gamma photon flux which depends on the position of the lightest object. We will focus more on 2 binary systems : LS 5039 and PSR B1259–63, we have a susbstantial data, H.E.S.S. telescopes have regularly observed these objects for more than 10 years. In 2012, a fifth telescope much larger size, began observations and enables to get events at lower energy and then make the connection with other experiments such as Fermi-LAT. A modelling of these two binary systems in anisotropic inverse Compton in Klein–Nishina regime are also presented and the circumstellar disk is taken into account for PSR B1259–63. Data taken by theH.E.S.S. telescopes can be improved. During observations, atmosphere can be degraded and thus affecting the flux of gamma photons collected. It’s therefore important to know the transparency coefficient of the atmosphere during an analysis. Furthermore, the electromagnetic air showers are more distorted because of the Earth’s magnetic field, a study of these phenomenas is necessary to correct these effects
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Hargreaves, T. J. "Acoustic diffusion and scattering coefficients for room surfaces." Thesis, University of Salford, 2000. http://usir.salford.ac.uk/14819/.
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This project concerns quantifying the diffuseness of sound reflections from surfaces by means of a diffusion coefficient. Afthough it is now acknowledged that diffuse reflections are important in determining sound fields within rooms, no standardised diffusion coefficient currently exists. Definition of a universal coefficient would permit comparison of different surfaces and aid the understanding of diffusion. It would also benefit diffuser designers and room acoustic computer modellers. Previously proposed diffusion parameters for room surfaces are investigated and new ones developed. One approach is to parameterise the uniformity of the scattered energy measured as a polar response; a number of such parameters have been previously published. These are appraised using measured and predicted 2D and 3D polar responses for a diverse range of sample surfaces. The situations in which the parameters succeed and fail are discussed and it is demonstrated that none is ideal. A new polar response coefficient, superior to those previously published, is presented. This satisfies many criteria of the ideal diffusion measure and is likely to be standardised by the Audio Engineering Society. It is shown that the application of all polar response diffusion parameters is, however, limited. Two recently proposed alternative approaches to evaluating a scattering coefficient, which involve measuring the invariance of the energy reflected from a surface to its orientation, are discussed. One of these is a free field technique and the other requires reverberant conditions. Practical analysis shows that the reverberation chamber method is superior. It is likely to be standardised by ISO. An empirical reverberation chamber technique is also investigated, as is the possibility of quantifying the diffusion efficacy of surfaces from their effect on sound field diffuseness. Both of these approaches require further research. It is concluded that to provide maAmum benefit, the choice of diffusion coefficient is application dependent.
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De, Silva Vashista C. "Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062904/.
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The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports our experiments and indicates that light goes mostly through the epsilon-near-zero shell with approximately wavelength independent absorption rate. Broadband extinction in fractal shells allows as well for a laser photoburning of holes in the extinction spectra and consequently windows of transparency in a controlled manner. Au fractal nanostructures grown on PCC flakes provide the highest mass normalized extinction, up to 3 m^2/g, which has been demonstrated in the broad spectral range. In the nanoplasmonic field active devices consist of a Au nanoparticle that acts as a cavity and the dye molecules attached to it via thin silica shell as the active medium. Such kind of devices is considered as a nano-laser or nano-amplifier. The fabricated nanolasers were studied for their photoluminescence kinetic properties. It is shown that the cooperative effects due to the coupling of dye molecules via Au nanoparticle plasmons result in bi-exponential emission decay characteristics in accord with theory predictions. These bi-exponential decays involve a fast superradiant decay, which is followed by a slow subradiant decay. To summarize, this work shows new attractive properties of core-shell nanoparticles. Fractal Au shells on silica cores prove to be a good scattering suppressor and a band pass filter in a broadband spectral range. They can also be used as an obscurant when PCC is used as the core material. Finally, gold nanoparticles coated with silica with dye results in bi-exponential decays.
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Jeyakumaran, R. "Some scattering and sloshing problems in linear water wave theory." Thesis, Brunel University, 1993. http://bura.brunel.ac.uk/handle/2438/5390.
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Using the method of matched asymptotic expansions the reflection and transmission coefficients are calculated for scattering of oblique water waves by a vertical barrier. Here an assumption is made that the barrier is small compared to the wavelength and the depth of water. A number of sloshing problems are considered. The eigenfrequencies are calculated when a body is placed in a rectangular tank. Here the bodies considered are a vertical surface-piercing or bottom-mounted barrier, and circular and elliptic cylinders. When the body is a vertical barrier, the eigenfunction expansion method is applied. When the body is either a circular or elliptic cylinder, and the motion is two-dimensional, the boundary element method is applied to calculate the eigenfrequencies. For comparison, two approximations, "a wide-spacing", and "a small-body" are used for a vertical barrier and circular cylinder. In the wide-spacing approximation, the assumption is made that the wavelength is small compared with the distance between the body and walls. The small-body approximation means that a typical dimension of the body is much larger than the cross-sectional length scale of the fluid motion. For an elliptic cylinder, the method of matched asymptotic expansions is used and compared with the result of the boundary- element method. Also a higher-order solution is obtained using the method of matched asymptotic expansions, and it is compared with the exact solution for a surface-piercing barrier. Again the assumption is made that the length scale of the motion is much larger than a typical body dimension. Finally, the drift force on multiple bodies is considered the ratio of horizontal drift force in the direction of wave advance on two cylinders to that on an isolated cylinder is calculated. The method of matched asymptotic expansions is used under the assumption that the wavelength is much greater than the cylinder spacing.
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Daniels, Timothy Vaughn Clegg Thomas B. "Spin-correlation coefficients and phase-shift analysis for p+3He elastic scattering." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2225.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Jun. 26, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics and Astronomy." Discipline: Physics and Astronomy; Department/School: Physics and Astronomy. On t.p., 3 in title is superscript.
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Mapingire, Hezekia. "Clebsch-Gordan coefficients and electron-phonon scattering in the valence band of Ge." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63287.
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The abstract contains mathematical symbols and do not display correctly. It can be read in the document attached.Dissertation (MSc)--University of Pretoria, 2017.
Physics
MSc
Unrestricted
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Ould-Kaddour, Latifa. "Etude par diffusion de la lumiere des systemes ternaires : polymere-polymere-solvant." Strasbourg 1, 1988. http://www.theses.fr/1988STR13006.
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Etude experimentale de plusieurs systemes ternaires, comportant deux polymeres differents en solution par diffusion de la lumiere. L'analyse de l'intensite diffusee a vecteur d'onde nul a permis de caracteriser les proprietes thermodynamiques et plus particulierement le parametre d'interaction entre les deux polymeres
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Weser, Robert. "Erfassung und Auswertung von Ultraschallechosignalen zur Charakterisierung konzentrierter disperser Stoffsysteme." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-158895.
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Die Charakterisierung von Dispersionen hat das Ziel, die Zusammensetzung und den Zustand von partikelhaltigen Stoffgemischen zu erfassen. Vor allem der Zustand der dispersen Phase (Partikel), der wiederum von der Größe und der Konzentration der Partikel bestimmt wird, ist in diesem Zusammenhang von besonderer Bedeutung. Neben optischen Verfahren, wie der Laserbeugung oder der Lichtstreuung, ist die Anwendung von akustischen Methoden vor allem dann sinnvoll, wenn die zu untersuchenden dispersen Stoffgemische opak und optische Methoden nur noch eingeschränkt (nach Verdünnung) anwendbar sind. Derartige Dispersionen weisen oftmals eine hohe Partikelkonzentration auf.
Die Erfassung und Auswertung von Ultraschallechosignalen aus konzentrierten Dispersionen stellt einen neuartigen Ansatz innerhalb der akustischen Partikelmesstechnik dar. Im Rahmen der vorliegenden Arbeit wurden theoretische und experimentelle Untersuchungen zum Ultraschallrückstreuverhalten von konzentrierten Dispersionen im unteren Megahertzbereich durchgeführt. Die messtechnische Erfassung der von der Dispersion reflektierten Schallanteile stellte eine besondere Herausforderung dar. Vor allem bei Partikeln, die klein gegenüber der Wellenlänge des Schalls sind oder einen geringen akustischen Kontrast gegenüber der kontinuierlichen Phase aufweisen, ist ein entsprechend schwaches Echosignal zu erwarten. Im Ergebnis der durchgeführten Untersuchungen zeigt sich eine hohe Sensitivität des akustischen Rückstreuverhaltens gegenüber der Zusammensatzung der Dispersion. Vor allem in konzentrierten Dispersionen kann die Messung direkt, d. h. ohne vorherige Verdünnung durchgeführt werden. Dieser Umstand prädestiniert das entwickelte Messverfahren für den Einsatz innerhalb der prozessnahen Charakterisierung von Partikelsystemen, beispielsweise bei Nasszerkleinerungs- oder Kristallisationsprozessen. Bei derartigen Prozessen ist eine Probenahme und Probenaufbereitung nicht oder nur eingeschränkt möglich.
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Parupudi, Arun Kumar. "Demonstration of scale-down dynamic light scattering and determination of osmotic second virial coefficients for proteins." Master's thesis, Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11092007-112135/.
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Pandini, D. "STUDI PER LA MODELLIZZAZIONE DELLA RIFLETTANZA SPETTRALE NEGLI STRATI PITTORICI." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168396.
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Nowadays a lot of physical techniques are available in order to have information about an historical painting. They are able to know which chemical elements are present in the paint layer, or they are also able to show the pattern under the colored layer, but there is not a non-destructive technique able to study the artist technique of painting or the historical pigments used in order to obtain the particular nuance we can observe.
In this thesis we study an evolution of the VIS-NIR-spectroscopic technique with these goals. In particular we start from a preliminary historical study of the artist’s pigments available for paintings and, starting from the colorimetric technique till the spectrophotometetric technique we create a representative pigments Database and we study a new method for pigment grindings identification, pigment’s mixture recognition and pigments layer technique studies.
The international method for color measurements provides the use of colorimeter but the sizes of these instruments don’t allow to perform measurements in any cases. Applications in the field of cultural heritage like as pigment characterizations on statues or ceramic and sometimes paintings don’t allow the use of integrating sphere. So we study the applicability of optical fiber for the realization of optical fiber remote probes. The use of optical fibre is consolidated for spectroscopy measurements (in particular for UV-VIS-NIR spectroscopy), but it may introduce an error in the detection of the spectra and, in consequence, a further error in the definition of the color of the sample analyzed. The first goal of this work was therefore the evaluation of compatibility of CIE colorimetric results obtained using Fiber Optic Reflectance Spectroscopy (FORS) and those values obtained with a standard colorimeter and then we extend the use of remote probe in NIR range for the measure of the pigments reflectance spectra.
After the test of the remote probe setup we have studied spectra obtained for well-defined mixtures of the most important artist’s pigments with the barium sulphate white pigment, the same used like standard sample for color measurements. These mixture simulate the different desaturation degree of the main color like in the earlier paintings techniques before Renaissance age. In order to have the best numerical characterization we fit the main behavior of the spectra using two analytical models: the Gaussian function (with 4 free parameters) and the sigmoidal function (with 4 free parameters): the comparison of their parameters allow to define the change of the spectra for different concentration of each colored pigment in the white one when thy were mixed in oil or without oil (as in oil renaissance paint technique and in the tipical affresco Middleage paint technique). Determination of weight mixture Pigment to white were: pigment pure, 1:1, 1:2, 1:5, 1:10, 1:20, 1:50. The pigments analyzed with sigmoidal fit were: Cadmium Red , Lacca rossa (Red Laquel), Chromium Orange, Cadmium Yellow, Naple Yellow (with Lead), Green Chromium oxide, Cobalt Blue, Cobalt Violet and Ultramarine Green. Pigments studied using Gaussian fit were: Green Chromium oxide, Cobalt Violet, Ultramarine Green, Verderame (Copper Green), Azurite, Ultramarine blue (artificial), Lapislazuli, Green earth, Malachite Green, Zinc Yellow and Cinabrum.
The next step is the research of a model able to study mixtures of two different colored pigments. The best historical model able to describe the interaction light-pigment was the Kubelka-Munk theory. In this model the Absorbtion (K) and Scattering (S) coefficients are needed. Here we study a method to obtain this coefficient from the reflectance spectra of the pigments and the spectra of their mixtures with barium sulphate and we use the same method in order to obtain the spectra of a mixture of two different colored pigment in an oil-paint layer.
The change of the color due to the presence of the oil is finest and the normal remote probes (optical fiber) setup is not enough to solve the differences, like it is not able for study the effect of the different grindings of the pigment’s powders. We realized an high-definition setup for reflectance measurements without optical fibers and a Fianium white LASER source (collaboration wit AMOLF-Fom institute, Amsterdam) creating also samples with characteristics nearest the Kubelka-Munk request. Using this high sensitivity setup we obtain the reflectance spectra for all the selected pigments and we study the difference of color due to the different grindings of the powder for the azurite and verderame pigments.
We were able also to study color differences of specific paint techniques of ancient painters: the “Italian” Renaissance technique based on the mixtures of color pigments and the “Flamish” technique based on the overlapping of translucent glaze of different color in order to obtain the deep in the paint and the famous sfumato.
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Lawrence, Heather. "MODÉLISATION DE L'EFFET DE LA RUGOSITÉ DE SURFACE ET DE LA LITIÈRE DES COUVERTS NATURELS SUR LES OBSERVATIONS MICRO-ONDES PASSIVES - APPLICATION AU SUIVI GLOBAL DE L'HUMIDITÉ DU SOL PAR LA MISSION SMOS." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-01024075.
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Dans le cadre de la mission spatiale SMOS (Soil Moisture and Ocean Salinity), nous présentons dans cette thèse une nouvelle approche numérique de modélisation du calcul de l'émissivité et du coefficient bi-statique de systèmes forestiers sol-litière en Bande L. Le système sol-litière est représenté par deux couches diélectriques 3D comportant des interfaces rugueuses, une démarche qui n'apparait pas actuellement dans la littérature. Nous validons notre approche pour une seule couche en comparant les simulations de l'émissivité avec celles produites par la méthode des moments et des données expérimentales. A partir de ce nouveau modèle, nous évaluons la sensibilité de l'émissivité du système sol-litière en fonction de l'humidité et de la rugosité de la litière. Ce nouveau modèle permettra de créer une base de données synthétiques d'émissivités calculées en fonction de nombreux paramètres qui contribuera à améliorer la prise en compte de la litière dans l'algorithme d'inversion des données de la mission spatiale SMOS.
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Maess, Johannes Thomas. "Attenuation models for material characterization." Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-10252004-031615/unrestricted/maess%5Fjohannes%5Ft%5F200412%5Fmast.pdf.
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Thesis (M.S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.Laurence J. Jacobs, Committee Chair ; Reginald DesRoches, Committee Member ; Jianmin Qu, Committee Member. Includes bibliographical references.
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Cassiani-Ingoni, Lionel. "Etude d'un hydrogel, copolymere (mma-co-vp) utilise comme precurseur de lentilles de contact : caracterisation du gel, diffusion et activite du lysozyme dans la matrice." Paris 6, 1987. http://www.theses.fr/1987PA066299.
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Barret, Laurie-Anne. "Influence des tensioactifs dans la cristallisation du complexe photosynthétique RC-LH1-pufX de Rhodobacter blasticus." Phd thesis, Université d'Avignon, 2013. http://tel.archives-ouvertes.fr/tel-01017895.
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Ce projet vise à étudier, par une approche pluridisciplinaire, l'influence des la cristallisation des protéines membranaires (PM) en prenant pour protéine modèle le complexe photosynthétique RC-LH1-pufX de Rhodobacter blasticus. Des cristaux de ce complexe avaient été obtenus en présence de dodécyl-!-maltoside (DDM) et avaient diffractés à 8 Å de résolution. L'objectif final est de pouvoir améliorer, de façon rationnelle, la qualité des cristaux du complexe RC-LH1-pufX grâce à une meilleure compréhension des mécanismes mis en jeu. Dans un premier temps, trois tensioactifs dérivés du DDM ont été conçus et synthétisés. L'intérêt est d'augmenter la rigidité et le caractère lipophobe des parties hydrophobes des tensioactifs par rapport au DDM, pour les rendre moins déstabilisants envers la protéine: soit par l'incorporation d'un groupement bicyclohexyle (PCC-maltoside), soit par l'ajout d'un segment fluoré de longueur modulable (F4H5- et F2H9-maltoside). Nous avons inclus également le F8TAC, tensioactif fluoré utilisé depuis une vingtaine d'années pour le maintien en solution des PM, et les "tripodes", amphiphiles faciaux dont la géométrie particulière n'avaient jamais été testée. Nous avons ensuite réalisé la caractérisation physico-chimique, en solution, de ces tensioactifs et du DDM en terme de CMC (concentration micellaire critique), nombre d'agrégation, taille (par diffusion de la lumière dynamique, DLS), facteur de forme (par diffusion des rayons X aux petits angles, SAXS) et facteur de structure (par mesure du second coefficient du viriel, indicateur du potentiel des tensioactifs à initier la cristallisation)afin de déterminer les caractéristiques importantes au maintien en solution et à la cristallisation des PM. Le PCC-malt présentant le même comportement que le DDM,nous l'avons sélectionné pour réaliser une étude en présence de la protéine.Après avoir mis au point une méthode de dosage des tensioactifs par HPTLC (HighPerformance Thin Layer Chromatography) et identifier les lipides présents dans les de Rhodobacter blasticus, nous avons pu quantifier les quantités de lipides et de tensioactifs associés à la protéine en présence de DDM et de PCC-malt.Enfin, dans une dernière partie, nous avons réalisé des essais de cristallisation du complexe RC-LH1-pufX en présence des tensioactifs sélectionnés pour faire le lien entre les conditions de cristallisation et l'étude physico-chimique des micelles en solution.
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Germond, Jeffrey. "Structural Characterization and Thermoelectric Performance of ZrNiSn Half-Heusler Compound Synthesized by Mechanical Alloying." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1197.
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Thermoelectric (TE) ZrNiSn samples with a half-Heusler atomic structure were synthesized by mechanical alloying (MA) and consolidation by either Spark Plasma Sintering (SPS) or hot pressing (HP). X-Ray diffraction patterns of as milled powders and consolidated samples were compared and analyzed for phase purity. Thermal conductivity, electrical conductivity and Seebeck coefficient are measured as a function of temperature in the range 300 K to 800 K and compared with measurements reported for high temperature solid state reaction synthesis of this compound. HP samples, compared to SPS samples, demonstrate increased grain growth due to longer heating times. Reduced grain size achieved by MA and SPS causes increased phonon scattering due to the increased number of grain boundaries, which lowers the thermal conductivity without doping the base system with addition phonon scattering centers. Mechanical characterization of the samples by microindentation and depth sensing indentation for hardness and elastic modulus will be discussed.
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Chang, Yongbin. "The Concept of Collision Strength and Its Applications." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4530/.
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Collision strength, the measure of strength for a binary collision, hasn't been defined clearly. In practice, many physical arguments have been employed for the purpose and taken for granted. A scattering angle has been widely and intensively used as a measure of collision strength in plasma physics for years. The result of this is complication and unnecessary approximation in deriving some of the basic kinetic equations and in calculating some of the basic physical terms. The Boltzmann equation has a five-fold integral collision term that is complicated. Chandrasekhar and Spitzer's approaches to the linear Fokker-Planck coefficients have several approximations. An effective variable-change technique has been developed in this dissertation as an alternative to scattering angle as the measure of collision strength. By introducing the square of the reduced impulse or its equivalencies as a collision strength variable, many plasma calculations have been simplified. The five-fold linear Boltzmann collision integral and linearized Boltzmann collision integral are simplified to three-fold integrals. The arbitrary order linear Fokker-Planck coefficients are calculated and expressed in a uniform expression. The new theory provides a simple and exact method for describing the equilibrium plasma collision rate, and a precise calculation of the equilibrium relaxation time. It generalizes bimolecular collision reaction rate theory to a reaction rate theory for plasmas. A simple formula of high precision with wide temperature range has been developed for electron impact ionization rates for carbon atoms and ions. The universality of the concept of collision strength is emphasized. This dissertation will show how Arrhenius' chemical reaction rate theory and Thomson's ionization theory can be unified as one single theory under the concept of collision strength, and how many important physical terms in different disciplines, such as activation energy in chemical reaction theory, ionization energy in Thomson's ionization theory, and the Coulomb logarithm in plasma physics, can be unified into a single one -- the threshold value of collision strength. The collision strength, which is a measure of a transfer of momentum in units of energy, can be used to reconcile the differences between Descartes' opinion and Leibnitz's opinion about the "true'' measure of a force. Like Newton's second law, which provides an instantaneous measure of a force, collision strength, as a cumulative measure of a force, can be regarded as part of a law of force in general.
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Pham, Thanh Tung. "Multiscale modelling and simulation of slip boundary conditions at fluid-solid interfaces." Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00980155.
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In most applications concerning a fluid flowing over a solid surface, the no-slip velocity condition was widely used because it is simple and produces the results in agreement with experiments. However, this dynamical boundary condition is not appropriate when the flow under consideration is at a micro or nano length scale.In order to model this effect at the macroscopic scale, the Navier boundary conditions have been introduced, with the slip length as a parameter. When the fluid is a gas, this length is related to the tangential momentum accommodation coefficient (TMAC) and the mean free path, according to the Maxwell model. The aim of this work is to systematically address this model using a multi-scale approach and to extend it by incorporating both the morphology and the anisotropy of a surface. The thesis consists of five chapters. In Chapter 1, the basics of the kinetic theory of gases, the Boltzmann equation and related solutions (Navier-Stokes-Fourier, Burnett, Grad, Direct Simulation Monte Carlo ...) are briefly presented. The models of gas-wall interaction and slip models introduced in the fluid mechanics are also recalled. The chapter ends with a description of the computational method used for the molecular dynamics simulations performed in this work. Chapter 2 is dedicated to the development of a simple technique to simulate the pressure driven flows. The principle is to rely on the atomistic formulas of the stress tensor (Irving Kirkwood, Method of Plane, Virial Stress) and to modify the periodic conditions by maintaining the difference between the kinetic energy of the ingoing and outgoing particles of the simulation domain. Several types of channels are studied with this technique. The results (temperature, velocity ...) are discussed and compared. Chapter 3 deals with the study of the gas-wall interaction potential by the ab-initio method. The code CRYSTAL 09 is used to obtain the potential between an atom of argon (Ar) and a surface of platinum (Pt) <111> as a function of distance. Then the gas-wall potential is decomposed into binary potential and approached by an analytic function. This function is then implemented in a MD code to simulate the gas-wall collisions and determine the TMAC coefficient. In Chapter 4, the effect of morphology is studied. The multi-body Quantum Sutton Chen (QSC) potential is used for Pt <100> solid and the binary potential proposed in the previous chapter for the Ar-Pt couple is employed. The QSC potential is needed to reproduce the surface effects that affect the final results. Different surfaces are treated : smooth, nanostructured surface and, random surface obtained by Chemical vapor deposition (CVD). The TMAC is determined using a generalized approach, i.e. depending on the angle of incident flux of gas atoms on the surface. The surface anisotropy and the scattering kernel are also examined. In Chapter 5, we propose a model of anisotropic slip for fluids based on accommodation tensor. The model is obtained by the analytical approximate calculations developed in the framework of the kinetic theory. We thus generalize Maxwell's equation by showing that the slip length tensor is directly related to the accommodation tensor. The model is in good agreement with the MD results. Thanks to our MD simulations, we develop a suitable technique for reproducing the anisotropy of the accommodation tensor. The thesis ends with a conclusion section in which we suggest some perspectives for a continuation of this work
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Sajjad, Naheed. "Bistatic scattering of electromagnetic waves from rough surface by using second order twoscale model : application to sea and bare soil surface." Brest, 2011. http://www.theses.fr/2011BRES2049.
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The estimation of radar cross section (RCS) of randomly rough surfaces is essential for designing terrain and sea surface remote sensing systems. The particular problem of wave scattering at low grazing angles is of great interest because of its importance for the low-altitude/long-range radar surveillance, target tracking, communication and navigation systems operating at low grazing conditions above the rough surface. The radar cross section from a rough surface becomes very small at grazing incidence, since most part of the incident power is scattered around the specular direction (depending on the degree of surface roughness). Moreover, the dominant scattering mechanisms at low and high grazing angles are different e. G. , the effects of multiple scattering (or higher order scattering), shadowing, fading and mechanisms attributable to wave breaking are particularly marked in the low grazing angle regime. Therefore, in this context the research has been conducted in this thesis. A second order two-scale model (TSM2) has been developed to study the bistatic scattering enhancement at grazing angles and the accurate depolarization estimation in a radar return. The applications of TSM2 are presented for sea and bare soil surfaces. The results obtained from newly developed model are compared with the available experimental data and other models to demonstrate the validity and efficiency of TSM2L’estimation de la surface équivalente radar (SER) des fouillis de mer et terrestre est essentielle pour la conception et l’amélioration des performances des systèmes de télédétection et d’observation de la planète. Le problème particulier de la diffusion des ondes en configuration à angle rasant est de grand intérêt à cause de son importance pour la surveillance, suivi de cible, la communication et les systèmes de navigation fonctionnant au-dessus de surfaces rugueuses, terrestre ou maritime. La surface équivalente radar d’une surface rugueuse devient très faible en incidence rasante puisque la plus grande partie de la puissance incidente est diffusée dans la direction spéculaire (selon le degré de rugosité de k surface). De plus, les mécanismes principaux de diffusion sont différents aux angles rasants, par exemple, les effets de diffusion multiple (ou de diffusion d’ordre supérieur), l’ombrage, fading et les mécanismes liés au déferlement des vagues sont particulièrement présents dans une telle configuration. Par conséquent, c’est dans ce contexte que s’intègre les travaux de recherche développés dans cette thèse. Ceci en développant le modèle deux échelles à l’ordre 2 (TSM2) permettant ainsi de contribuer à l’estimation des coefficients de diffusion bistatique par les surfaces rugueuses avec l’application de ce modèle aux surfaces maritime et terrestre. L’évaluation du modèle développé est réalisée en effectuant des comparaisons par rapport aux résultats obtenus avec d’autres modèles et aussi aux données issues de la littérature ouverte
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Smith, Heather. "Geometric Acoustic Modeling of the LDS Conference Center." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd591.pdf.
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Ben, Khadra Slahedine. "Etude de la signature EM bistatique d'une surface maritime hétérogène avec prise en compte des phénomènes hydrodynamiques." Thesis, Brest, 2012. http://www.theses.fr/2012BRES0089/document.
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Le travail réalisé dans cette thèse s'intègre globalement dans le cadre de I'observation et la surveillance maritime.Afin d'améliorer la reconnaissance et I'identification automatique de cibles noyées dans un environnement perturbé, nous avons opté à la fusion de différentes connaissances et informations concernant une scène observée à distance par des capteurs micro-ondes. En effet, plusieurs phénomènes physiques co-existent et perturbent la propagation des ondes électromagnétiques au-dessus d'une surface et notamment au-dessus d'une surface maritime hétérogène (la réfraction due aux gradients d'indice, la rugosité de la surface de mer, les effets hydrodynamiques non linéaires du type vagues déferlantes, la présence d'objets, les polluants, sillage de navires, zones côtières, ...). Dans ce contexte, le travail présenté dans cette thèse porte sur l'étude de la signature électromagnétique (coefficients de diffusion) d'une surface maritime hétérogène avec la prise en compte des phénomènes hydrodynamiques (linéaires : vagues de capillarité et de gravité, non linéaires : vagues déferlantes). Cette estimation de la signature électromagnétique est effectuée en configuration bistatique (monostatique et propagation avant) et en bande X. L'étude complète de cette problématique est difficile. En effet, le déferlement est un processus dissipatif de l'énergie qui correspond à la dernière étape de la vie d'une vague et qui a donc le plus souvent lieu à I'approche du rivage. Ce phénomène non linéaire produit un pic de mer qui est une augmentation rapide des coefficients de diffusion et qui peut dépasser 10 dB dans une période de 100 ms. Ce pic peut conduire à des échos parasites, qui peuvent être identifiés comme des cibles virtuelles, et par la suite elles peuvent perturber le système de détection radar (fausses alarmes). Par conséquent, pour améliorer le processus de détection et pour réduire le taux de fausses alarmes, il est important de distinguer entre les cibles et les pics de mer générés par des vagues déferlantes. Ceci constitue I’une des motivations et aussi I'intérêt d'étudier la signature électromagnétique des vagues déferlantes dans différentes configurations d'observation de sorte que nous puissions facilement indiquer la présence voir I'identification des pics de mer. Pour contribuer à cette problématique, nous avons proposé une méthodologie basée sur un modèle électromagnétique hybride basé sur une combinaison d'une part de méthodes asymptotiques(SPMI utilisée dans le cadre de ce travail) pour simuler la réponse radar des vagues linéaire (vagues de capillarité et de gravité décrites via le spectre de mer d'Elfouhaily), et d'autre part de méthodes exactes (MoM, FB < Forward-Backward ) retenue dans le travail présenté dans ce manuscrit) pour calculer la réponse électromagnétique des vagues non-linéaires (profils considérés sont issus des résultats du code LONGTANK). Afìn de compléter l'étude théorique et les simulations réalisées, nous avons effectué une phase d'évaluation et de validation par des mesures de signature radar réalisées dans la chambre anéchoïque de I'Ensta BretagneThe work done in this thesis fits generally under the observation and maritime surveillance. To improve the detection and automatic identification of targets embedded in a noisy environment targets, we opted for the fusion of different knowledge and information regarding a remotely observed scene by microwave sensors. Indeed, several physical phenomena co-exist and interfere with the propagation of electromagnetic waves over a heterogeneous sea surface (the refraction due to the index gradients, the roughness of the sea surface, nonlinear hydrodynamic effects like waves breaking, the presence of objects, pollutants, ship wake, coastal areas,..). In this context, the work presented in this thesis focuses on the study of electromagnetic signature (diffusion coefficients) of a heterogeneous sea surface with consideration of hydrodynamic phenomena (linear: capillary and gravity waves, nonlinear: breaking waves). The electromagnetic signature is performed in bistatic configuration (monostatic and forward propagating) and in X-band. The complete study of this problem is difficult.Indeed, the breaking wave is a dissipative process of energy that corresponds to the last stage of the life of a wave and therefore has most often held in the shore. This nonlinear phenomenon produces a sea peak which is a rapid increase of the diffusion coefficients and can exceed l0 dB in a 100 ms period. This peak can lead to clutter, which can be identified as virtual targets, and then they can disrupt the detection radar system (false alarms). Therefore, to improve the detection process and reduce the false alarm rate, it is important to distinguish between targets and sea peaks generated by breaking waves. This represents one of the motivations and also the interest to study the electromagnetic signature of breaking waves in different observation configurations so that we can easily detect and identify the sea peaks. To solve this problem, we proposed a methodology based on a hybrid electromagnetic model which is on a combination of asymptotic methods (SPMI used in this work) to simulate the radar response of linear waves (capillary and gravity waves described via the Elfouhaily sea spectrum) and an exact methods, the method of moment (the FB "Forward-Backward" method is used in this work), to calculate the electromagnetic response of nonlinear waves (profiles are produced by the LONGTANK code). To complement the theoretical study and simulations, we carried out an evaluation and validation phase by measuring the radar signature of breaking wave profiles in the ENSTA Bretagne anechoic chamber
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Neubauer, Svetlana. "Untersuchungen von inter- und intramolekularen Interaktionen des globalen Regulators AbrB und dessen Antirepressors AbbA." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16887.
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Aus den frühen Bindungsstudien des globalen Regulators AbrB mit der ausgedehnten phyC-Promotorregion von Bacillus amyloliquefaciens FZB45 konnte ein mehrstufiger kooperativer Bindungsprozess abgeleitet werden. Dabei verlangt die AbrB-vermittelte Repression von phyC nach Integrität zweier großer Bindungsstellen, ABS1 und ABS2, die 162 bp voneinander entfernt liegen. In der vorliegenden Arbeit wurden die ersten Echtzeitkinetiken zur DNA-AbrB-Interaktion mittels der Oberflächenplasmonresonanz (SPR) gemessen und analysiert. AbrB zeigte hohe Affinitäten zu den 40 bp langen Oligonukleotiden, die den beiden Bindungsstellen entstammen. Dabei verursachten alle Oligonukleotide der ABS2 und nur eine kurze Region innerhalb der ABS1 bei der Bindung von AbrB Konformationsänderungen im Protein und in der DNA (CD - Zirkulardichroismusspektroskopie) und wiesen eine Kooperativität von 2In previous binding studies it could be demonstrated that a global regulator AbrB and the extensive phyC promoter region of Bacillus amyloliquefaciens FZB45 interact in a complex manner. AbrB binding is a multistep cooperative process. The integrity of both binding sites, ABS1 and ABS2, which are separated by 162 bp, is crucial for the AbrB-mediated repression of phyC. This work presents the first real-time binding kinetics of the AbrB-DNA interaction using surface plasmon resonance (SPR). AbrB exhibited high affinities to all analyzed 40-bp oligonucleotides that were derived from the ABSs of phyC. All parts of the ABS2, but only a small region within ABS1, were bound cooperatively to AbrB with a stoichiometry of 2 DNA to 1 AbrB tetramer and with 2
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Chen, Lu-Yen, and 陳律言. "Influence of relative humidity on particles' scattering coefficient." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65409124982209468364.
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博士國立臺灣大學
環境工程學研究所
92
Size distribution and scattering coefficients of particles are significantly influenced by relative humidity (RH). The scattering coefficient change caused by particles’ size change is especially important for environments with high relative humidity. In order to quantify the effects of RH change on scattering coefficients of particles, the hygroscopic growth of particles and size change occurring in scattering measurement instrument, integrating nephelometer, are investigated in this study. Hygroscopic growth of particles of different sizes and the resultant size distribution changes were observed as a function of the relative humidity (RH). A particle generation device, relative humidity module, and a Tandem Differential Mobility Analyzer system were set up to measure the particle size distributions under different RH conditions. Adopting Nafion as an RH adjusting module, the aerosol hygroscopic observations were successfully performed without the interference caused by blending sample stream with humidified air. The measured deliquescence humidity of model compounds, NaCl and (NH4)2SO4, agree with the theoretical values reported by other investigators. The particle growth factor is enhanced around the RH of 70%. In addition, particle size distribution behaves as two split groups of particles with the RH greater than 76%. The average growth factors of hygroscopic ambient particles in Taiwan are similar to those reported elsewhere. There are several hygroscopic salt compositions in ambient aerosols, (NH4)2SO4 is the most abundant one. Observed particle deliquescence behaviors showed limited alternation of organics on particle growth at higher RH. Nephelometer is widely used to measure the scattering coefficient of ambient particles. The sample stream is heated in nephelometer to avoid the possible formation of water film on the inner wall of nephelometer. The relative humidity change of heated sample stream also alters particles’ size distribution. In order to clarify the meaning of scattering coefficient measured by nephelometer, it is necessary to quantify the difference of measured and true scattering coefficient of ambient particles. In this study, the flow field, temperature field, and relative humidity field of nephelometer’s test chamber are solved by computational fluid dynamics. The corresponding scattering coefficient changes are calculated for three different types of particles including typical urban particles, rural particles, and marine particles. For sample stream with 90% relative humidity, the measured particle scattering coefficient is 63.5%, 41.7%, and 72.5% lower than the ambient particle scattering coefficient for typical urban particles, rural particles, and marine particles, respectively. For typical urban particles and rural particles, the differences between measured and ambient particle scattering coefficients are larger in environments with higher relative humidity. The differences range from 23.8% to 63.5% for typical urban particles, from 8.4% to 41.7% for rural particles. For marine particles, this difference is about 70%, and not sensitive to relative humidity.
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Chen, Endom, and 陳英堂. "Aerosol Distribution and Scattering Coefficient Measuring in Taiwan Area." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/07868505602992134754.
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碩士國立中央大學
環境工程學系
84
The scattering and/or absorption of atmospheric aerosols to the solar radiation play an important role in the global change as well as in the global weather change. Atmospheric aerosols were collected at Chungli and Tainan each for a month from fall to winter in 1995. A scanning mobility particle sizer ( TSI model 3934 SMPS ) and an aerosol spectrometer ( PMS model PCASP- X ) were used to measure aerosol size distribution, and an integrating Nephelometer was set up to acquire aerosol light- scattering coefficient. In the meantime, fine particles ( cut- size ≦2.5μm ) were sampled through an annular denuder to investigate chemical species of aerosol mass and their precursor gases. The green-wavelength light-scattering coefficients measured at Chungli were in the range of 5*10-5 and 1.5*10-4 m-1, while those at Tainan were varied from 1*10-4 to 3*10-4 m-1. The aerosol light-scattering coefficients acquired in this work are consistent with values reported in other urban area. Among the three methods in estimating aerosol light-scattering coefficients evaluated in this study, the statistical regression model from chemical species is the most accurate one but lacks of stability, the simplified theoretical model possesses both the high accuray and stability, the MAR theoretical model ( Wilson and Reist, 1994 ) has a good performance on estimating Tainan data but was bad in Chungli data.
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Chia-LunLiu and 劉家綸. "Numerical Calculation and Analysis of A Plate Crack Scattering Coefficient." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85833803323296627502.
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碩士國立成功大學
系統及船舶機電工程學系碩博士班
101
Time Reversal Method (TRM) is now widely used in under water exploration, medical testing and on the structure of non-destructive testing. In theory Iterative Time Reversal Process and Decomposition of Time Reversal Operator (D.O.R.T.) appears to solve many issues, simply are not resolved by utilizing the time reversal method. Further expand the time reversal theory application scope. While using this process for time reversal, the cumbersome process of iterative experiments can be eliminated directly by the mathematical derivation obtained from the iteration results. This research will explore the application of the D.O.R.T. theory in analyzing the scattering coefficient related to the signal refracting off the cracked plate, along with the affect of repositioning the signal at different angle in retrospect to the crack on the plate. As one component of this simulation, the ANSYS finite element software is implemented to stimulate the plate structure and retrieve the signal transmitter. Writing MATLAB programs, processing applications along with outputting scattered patterns are inclusive with the signal analysis. The simulation is ran by emitting signals from a transducer on two plates, one with cracks and one without cracks, the signal is emitted and captured. These two sets of signals are subtracted in order to obtain the scattered signals refracted from the cracked plate. In the time domain the signals are convoluted, and in the frequency domain they are multiplied. Multiplying in the frequency domain is significantly simpler, so Fast Fourier Transform(FFT) is used to convert the signal from the time domain to the frequency domain. We are able to derive the frequency domain signal that is arranged in the transfer matrix by utilizing the D.O.R.T. theory. Then the transfer matrix is used to calculate the scattering coefficient. Circular-shaped array transducers are used to calculate the various angles of the scattering coefficient, which we used to draw the scattered patterns. A characteristic chart is developed to differentiate the scattering characteristics of different size and shaped cracks. By this method to establish a calculation of the scattering coefficient in each direction. Wish this method applied in practice, and have a further contribution for non-destructive testing.
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Tsai, Chiung-Cheng, and 蔡炯禎. "The measuring of Tainan spring aerosol size distribution and scattering-coefficient." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/95376109314767758757.
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碩士國立中央大學
環境工程學系
85
Abstract The scattering and/or absorption of atmospheric aerosols to solar radiation play an important role in direct radiative forcing of climate. Atmospheric aerosols were collected at Tainan for nearly two month in the springtime of 1997. An aerosol spectrometer (PMS model PCASP- X) was used to measure aerosol size distribution, and an integrating nephelometer (TSI model 3563) was set up to acquire aerosol light-scattering coefficient (ssp). Moreover, two collocated MOUDI (Micro-orifice Uniform Deposit Impactor) samplers were installed at the site to collect sub-micron aerosols for chemical analysis. The daily averages of ssps from green-wavelength measured at Tainan were in the range of 0.06 to 0.48 Km-1. The results are consistent with those measured at other urban areas in the world. Meanwhile, the ssp is found in this work to have a close relation with meteorological factors. A rapid increase of ssp is shown when relative humidity reaches 75~80% and above. This environmental humidity is consistent with the deliquescent point of hygroscopic aerosols. Another finding displays wind speed exhibits an inverse relationship with ssp. The pollution event analysis shows that source emissions or dense fog has a great effect on short term ssp, sub-micron particles are found to be influenced most among all sizes. For springtime aerosols collected at Tainan, the resolved major chemical species including sulfates, nitrates, elemental carbon, and organic carbon. As a correlation matrix analysis shows, the ssp is related to sub-micron aerosol mass, nitrates, sulfates, ammonium ions, and aerosol water contents. Both the linear regression model and simplified theoretical model for estimating ssp are very consistent with the measured ssp. The results imply that either aerosol physical property (theoretical model) or chemical property (regression model) for estimating ssp is applicable.
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Lin, 秀姿, and 林秀姿. "Characteristics of atmospheric Aerosols in Taiwan- aerosol light-scattering coefficient aerosol size distribution." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/98874546037218891291.
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碩士國立中央大學
環境工程學系
86
The light scattering of atmospheric aerosols are important in radiative forcing in global warming. Among factors affecting aerosol light-scattering coefficient (ssp), aerosol size distribution has been known to be a major one. Although ssp is an integrating effect from all sizes of aerosols, a revelation of significant sizes in determining ssp is crucial in evaluating the control measures for atmospheric visibility. In the present study, a system consists of a scanning mobility particle sizer (SMPS, TSI Model 3934) and an integrating nephelometer (TSI Model 3563) was set up to assess shape effects on ssp size distribution and measure ssp size distribution. For the same mobility diameter, ssp is shown increased with an increasing ratio of long-to-short axis among sphere, short prism, and long prism. Meanwhile, aerosol back- scattering coefficient is decreased for an increasing ratio of long-to-short axis. The ssp size distribution was measured both at the campus of National Central University (NCU, in a suburban area) and at Sun-chun air quality monitoring station (on a traffic laden road). The results at NCU site showed a uni-modal ssp size distribution with a peak diameter at 0.5mm and the ssp in the range of 0.06~0.14Km-1. In contrast, Sun- chun site showed a bi-modal ssp size distribution with peak diameters at 0.45mm and 0.65 mm, individually, and the ssp in the range of 0.08~0.36Km-1. In the present study, a theoretical ssp size distribution is calculated from Mie theory and the measured aerosol size distribution. For a comparison, the ratio of the sum from theoretical ssp size distribution to that from measured ssp size is 89% and 82% at NCU site and Sun-chun site, individually. Meanwhile, the ratio of theoretical ssp to the sum from theoretical ssp size distribution is 80% and 81% at NCU site and Sun-Chun site ,individually.
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Yu-WenChen and 陳昱文. "Development of a precise algorithm based on Mie theory to recover the absorption coefficient, scattering coefficient and phase function of biomedical superficial tissue." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/65y5cv.
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Lin, Li-Wei, and 林立偉. "Aerosol size distribution and the effects of meteorological factors on aerosol scattering coefficient in Kenting area." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/09013485009300044292.
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碩士國立中央大學
環境工程研究所
87
Aerosol particles play an important role in global environmental change due to their scattering and absorption of solar radiation received by the earth. In this study, atmospheric aerosols were collected at Kenting National Park from October to December in 1998. An aerosol collection system consisted of aerosol spectrometer to acquire aerosol size distribution, an Integrated Nephelometer to measure aerosol scattering coefficients(ssp), and a weather station to collect the meteorological factors of the site. The objectives of this study are to characterize the physical properties of the background aerosols in Taiwan during the prevailing northeast monsoon and to investigate the effects of meteorological factors on the physical properties. A backward trajectory analysis combined with chemical speciation on aerosols were employed to evaluate the effects of the airflow transport on ssp. The results show the average ssp of green wavelength was 0.046 km-1 with daily averages ranged from 0.009 to 0.127 km-1 during the sampling period. The ssp was found a high correlation (R2 = 0.9) with the corresponding value calculated from Mie theory (Bohren and Huffman, 1983). The calculated ssp was 4.6% higher than the measured value. A discussion of the on/off heater effect on ssp showed the calculated ssp from aerosol spectrometer was 8% higher than that measured from the Nephelometer. As the calculated ssp showed, supermicron and submicron aerosols contributed 44% and 56% during the prevailing northeast monsoon at Kenting site. The variation of ssp was highly correlated with meteorological factors. For relative humidity below 75%, the ssp was decreased with an increasing wind speed as wind speed lower than 7ms-1, however, the trend was opposite as wind speed higher than 7ms-1. In contrast, as relative humidity higher than 75%, the ssp increased with an increasing wind speed. A higher ssp was found as the wind came from northwest and southwest. An increase of ssp was observed with the enhancement of submicron aerosols as an event was noted in the nearby area. During the sampling period, the synoptic weather patterns can be classified into five major types, i.e., weak northeast monsoon, Pacific high, prevailing northeast monsoon, the outer circulation of the tropical cyclone, and cold front. As eight-hour backward trajectory (Dharmavaram, 1987) shows, a high ssp with more secondary aerosols is usually associated with weak southwesterly flow passing over the sea and weak northeasterly flow from the land under Pacific high. In this weather type, 83% of ssp was found to be contributed from submicron aerosols. As the weather pattern shifted to prevailing northeast monsoon, the strong northeasterly wind from the sea brought more sea-salt aerosols to the site. The fraction of ssp contributed from supermicron and submicron aerosols was approximately the same. Combining weather patterns, chemical species of aerosols, and measured ssp showed ssp and sulfate were in a good agreement as the weather pattern was weak or prevailing northeast monsoon.