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Letteratura scientifica selezionata sul tema "Scattering anisotropy factor"

Autore: Grafiati

Pubblicato: 30 maggio 2022

Ultima modifica: 31 maggio 2022

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Articoli di riviste sul tema "Scattering anisotropy factor"

Беликов, А. В., А. М. Загорулько, С. Н. Смирнов, А. Н. Сергеев, А. А. Михайлова e А. А. Шимко. "Оптические свойства in vitro катарактальных хрусталиков глаза человека в видимом и ближнем ИК диапазонах-=SUP=-*-=/SUP=-". Журнал технической физики 126, n. 5 (2019): 656. http://dx.doi.org/10.21883/os.2019.05.47667.16-19.

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Spectral dependences of absorption coefficient, scattering coefficient, anisotropy factor and reduced scattering coefficient for in vitro human eye lenses of different cataract type are investigated. The spectra of absorption coefficient and reduced scattering coefficient were obtained for the spectral range 400-2300 nm, and the spectra of scattering coefficient and scattering anisotropy factor - for the spectral range 400-1800 nm. The regions of wavelengths within which the spectra of the studied optical characteristics of the human eye lens are not statistically significantly different for samples with different stages of cataract maturity and, conversely, within which they are statistically significantly different, are determined.

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Dumont, M., O. Brissaud, G. Picard, B. Schmitt, J. C. Gallet e Y. Arnaud. "High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results". Atmospheric Chemistry and Physics Discussions 9, n. 5 (16 settembre 2009): 19279–311. http://dx.doi.org/10.5194/acpd-9-19279-2009.

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Abstract. High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF) were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first set of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In constrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles.

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Dumont, M., O. Brissaud, G. Picard, B. Schmitt, J. C. Gallet e Y. Arnaud. "High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results". Atmospheric Chemistry and Physics 10, n. 5 (11 marzo 2010): 2507–20. http://dx.doi.org/10.5194/acp-10-2507-2010.

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Abstract. High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF) were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first sets of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In contrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles. The whole dataset is available on demand from the corresponding author.

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Kao, Meng-Chun, Che-Yen Kung, Chun-Li Lin e Wen-Chuan Kuo. "Simultaneous Measurement of Multiple Scattering Coefficient and Scattering Anisotropy Factor in Dental Demineralization". Journal of Medical Imaging and Health Informatics 5, n. 8 (1 dicembre 2015): 1859–63. http://dx.doi.org/10.1166/jmihi.2015.1659.

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Popescu, Dan P., e Michael G. Sowa. "In Vitro Assessment of Optical Properties of Blood by Applying the Extended Huygens-Fresnel Principle to Time-Domain Optical Coherence Tomography Signal at 1300 nm". International Journal of Biomedical Imaging 2008 (2008): 1–6. http://dx.doi.org/10.1155/2008/591618.

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A direct method for the measurement of the optical attenuation coefficient and the scattering anisotropy parameter based on applying the extended Huygens-Fresnel principle to optical coherence tomography images of blood is demonstrated. The images are acquired with a low-power probing beam at the wavelength of 1300 nm. Values of 12.15 mm−1and 0.95 are found for the total attenuation coefficient and the scattering anisotropy factor, respectively. Also, as a preliminary step, the optical refraction index is determined with a precision of two decimal numbers directly from optical coherence images. The total attenuation coefficient and the scattering anisotropy factor are determined with precisions within experimental error margins of 5% and 2%, respectively. Readable OCT signal is obtained for a maximum propagation of light into blood of 0.25 mm. At the maximum probed depth, the measured signal is almost103smaller than its initial intensity when entering the sample.

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Buchen, Johannes, Wolfgang Sturhahn, Takayuki Ishii e Jennifer M. Jackson. "Vibrational anisotropy of <i>δ</i>-(Al,Fe)OOH single crystals as probed by nuclear resonant inelastic X-ray scattering". European Journal of Mineralogy 33, n. 4 (17 agosto 2021): 485–502. http://dx.doi.org/10.5194/ejm-33-485-2021.

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Abstract. The formation of high-pressure oxyhydroxide phases spanned by the components AlOOH–FeOOH–MgSiO2(OH)2 in experiments suggests their capability to retain hydrogen in Earth's lower mantle. Understanding the vibrational properties of high-pressure phases provides the basis for assessing their thermal properties, which are required to compute phase diagrams and physical properties. Vibrational properties can be highly anisotropic, in particular for materials with crystal structures of low symmetry that contain directed structural groups or components. We used nuclear resonant inelastic X-ray scattering (NRIXS) to probe lattice vibrations that involve motions of 57Fe atoms in δ-(Al0.87Fe0.13)OOH single crystals. From the recorded single-crystal NRIXS spectra, we calculated projections of the partial phonon density of states along different crystallographic directions. To describe the anisotropy of central vibrational properties, we define and derive tensors for the partial phonon density of states, the Lamb–Mössbauer factor, the mean kinetic energy per vibrational mode, and the mean force constant of 57Fe atoms. We further show how the anisotropy of the Lamb–Mössbauer factor can be translated into anisotropic displacement parameters for 57Fe atoms and relate our findings on vibrational anisotropy to the crystal structure of δ-(Al,Fe)OOH. As a potential application of single-crystal NRIXS at high pressures, we discuss the evaluation of anisotropic thermal stresses in the context of elastic geobarometry for mineral inclusions. Our results on single crystals of δ-(Al,Fe)OOH demonstrate the sensitivity of NRIXS to vibrational anisotropy and provide an in-depth description of the vibrational behavior of Fe3+ cations in a crystal structure that may motivate future applications of NRIXS to study anisotropic vibrational properties of minerals.

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Tong, S. Y., C. W. Mok, Huasheng Wu e L. Z. Xin. "Role of scattering-factor anisotropy in electron, positron, and photon holography". Physical Review B 58, n. 16 (15 ottobre 1998): 10815–22. http://dx.doi.org/10.1103/physrevb.58.10815.

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Baranyai, László, e Manuela Zude. "Analysis of laser light migration in apple tissue by Monte Carlo simulation". Progress in Agricultural Engineering Sciences 4, n. 1 (1 dicembre 2008): 45–59. http://dx.doi.org/10.1556/progress.4.2008.3.

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The distribution of laser light in the tissue of Golden Delicious and Idared apples was measured with backscattering imaging and simulated with Monte Carlo (MC) method. The settings of the vision system (sensitivity and resolution) and the parameters of the laser modules (wavelength, power and beam diameter) were used in a time resolved MC model to optimize the computation. The 1 ns pulse containing 1.42 × 10 7 (at 670 nm) and 2.49 × 10 8 (at 785 nm) photons was selected for the simulation of backscattering on the fruit surface. The statistical effect of the scattering coefficient (µ s ), absorption coefficient (μ a ), and anisotropy factor ( g ) on photon flux and shape of the backscattering profile was evaluated within ±20 % range relative to expected mean values for apple tissue (µ a = 0.63 cm −1 , µ s = 30.0 cm −1 and g = 0.8). The multi-factor ANOVA test pointed out the highest importance (p<0.001) of the anisotropy factor compared to the scattering and absorption coefficients. Decreasing value of anisotropy factor enhanced the maximum intensity and increased the decline of the gradient resulting in a rotation of the intensity profiles. The measured backscattering profiles for Golden Delicious apples responded to bruising (p<0.05) already after one day storage.

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Stocker, Sabrina, Florian Foschum e Alwin Kienle. "Spatially Resolved Lateral Transmission Measurements to Characterize Changes in the Scattering Coefficient and the Anisotropy Factor". Applied Spectroscopy 72, n. 5 (21 febbraio 2018): 757–64. http://dx.doi.org/10.1177/0003702818757520.

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A new setup is described to characterize the scattering coefficient and the scattering phase function of liquid media. The setup utilizes the basic idea of a spatially resolved reflectance measurement combined with a sophisticated illumination geometry. The sample is illuminated parallel and close to the interface of the sample and a glass window to get information from single scattered and multiple scattered light. By illuminating the sample with a fiber orientated with the axis parallel to the glass surface, small distances to the source can be examined unimpeded by the illumination beam. The derived information is, for example, not only sensitive to the concentration of the scatterers but also to the size of the scattering particles. We present the setup including the theory to describe the light propagation in the whole configuration using Monte Carlo simulations. The validation has been done with polystyrene microsphere dispersions with different scattering coefficients. As application for the developed setup, we show measurements of different milk samples which vary in concentration of fat, protein, and in fat droplet size during homogenization process. By measuring milk, we show the ability of the sensor to determine information about the scattering phase function without diluting the sample. For sensors in the dairy industry, a measurement with no pre-processing and no diluting of the sample is worthwhile, because this can be used to determine the fat and protein concentration on-line.

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Mettus, Denis, e Andreas Michels. "Small-angle neutron scattering correlation functions of bulk magnetic materials". Journal of Applied Crystallography 48, n. 5 (29 agosto 2015): 1437–50. http://dx.doi.org/10.1107/s1600576715013187.

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On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g.elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g.the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strengthHpto the jump ΔMin the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratioHp/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel.

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Tesi sul tema "Scattering anisotropy factor"

Безугла, Наталя Василівна. "Просторова фотометрія біологічних середовищ". Thesis, НТУУ "КПІ", 2016. https://ela.kpi.ua/handle/123456789/15918.

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Дисертаційна робота присвячена розробці методу фотометричного аналізу біологічних середовищ шляхом розширення простору визначення їх оптичних властивостей, що дозволило одночасно врахувати характеристики відбитого та пропущеного середовищем оптичного випромінювання в межах повного тілесного кута. У роботі розроблено методики реалізації математичного базису просторової фотометрії біологічних середовищ за принципами визначення інтенсивності розсіяння по паралелях (кільцевих смугах) та меридіанах (перетинах). Запропоновані схемо-технічні рішення двох- та восьми-канальної інформаційно-вимірювальних систем для просторової фотометрії за перетинами, реалізовані на рівні експериментальних установок. Розроблено програмне забезпечення фотометричного паралельного аналізу, що дозволяє досліджувати індикатриси розсіяння за перетинами. Проведено аналіз індикатрис розсіяння лазерного випромінювання товщинними зразками м’язових тканини на різних довжинах хвиль та з різним розміщенням волокон. Здійснено перехід від індикатриси розсіяння товщинними зразками до фактору анізотропії однократного розсіяння. Доведено ідентичність експериментально-визначених величин оптичних коефіцієнтів дифузного відбиття та повного пропускання та визначених за результатами Монте-Карло моделювання з використанням усередненої за перетинами величини фактору анізотропії однократного розсіяння.
The thesis is devoted to developing the method of photometric analysis of biological media by expansion the space of definition their optical properties. That made possible the simultaneously consider the characteristics of the optical radiation, reflected and transmitted by biological media, within the full solid angle. In the work the main methods of solution the basic equation of radiative transfer theory in problems of optical biomedical diagnostics, were analyzed. Thus, the main attention focused on optical parameters of biological media: scattering (μs), absorption (μa) coefficients, and the anisotropy factor of single scattering (g), which are responsible for spatial distribution of scattered radiation by normal and pathology tissues or media (first order approximation, diffuse approximation, small angle approximation, flux models, Monte Carlo method). Conditions of use depending the type of biological media are described. The phase functions of single scattering (Mie, Henyey-Greenstein, Gegenbauer kernel, Delta-Eddington, Eddington), which used to describe the propagation the optical radiation in different types of biological media, were considered. Systematized the methods and tools of biophotonics with the possibilities of spatial-oriented analysis of radiation, scattered by sample of biological media, organs and body parts. Goniometric and spherical types of experimental setup are the most appropriated types that can used for spatial photometry. Photometric image of varying thickness samples of biological media by ellipsoidal reflectometry were received. Based on experimental research, the axial asymmetry of anisotropy of scattering by porcine and chicken muscle tissues of varying thickness in vitro at a wavelength of 632.8 nm was found. The influence of anisotropy of scattering on accuracy of determination the optical coefficients of diffuse reflection and total transmission by method Monte Carlo was demonstrated. Study of spatial anisotropy scattering by method of photometry was suggested. On this basis, has developed methods of implementing of the mathematical basis of spatial photometry of biological media by determining the scattering intensity along parallels (circular bands) and meridians (sections). The mechanism of the transition from experimentally determined indicatrix of scattering of thick sample to the anisotropy factor of single scattering by designed methods is proposed. The proposed scheme-technical versions of information-measurement system for spatial photometry along sections with two and eight channel, which were realized in experimental setups of goniometric and spherical type. The features of element synthesis, exploitation and calibration of setups are described. The interfaces and methods of application of developed software for parallel photometric analysis "IMSOB" and "IMSOB-2", to support research the scattering indicatrix along sections in reflected or transmitted light for two- and eight-channel systems respectively are given. The method of sample preparation of biological media and features of experiment for different experimental setups of spatial photometry are given. The methodology of preparation the biological samples used for research in this paper were detail described. The analysis of the indicatrix of laser light scattering by thick samples of muscle tissue at different wavelengths with transverse and longitudinal placement of fibers was made. The data obtained by method of spatial photometry, which realized the principle of analyses of the sections. Experimental studies conducted on goniometric type setup. For phase function of single scattering Henyey-Greenstein, modified by isotropic component in each sections, the transition from indicatrix scattering of thick sample to the single scattering anisotropy factor g was made. Identity of experimentally-determined values of the optical coefficients of diffuse reflection and total transmission and determined by the results of Monte Carlo simulation using the average values by sections of the anisotropy factor of single scattering are approved.
Диссертация посвящена разработке метода фотометрического анализа биологических сред путем расширения пространства определения их оптических свойств, что позволило одновременно учесть характеристики отраженного и пропущенного средой оптического излучения в пределах полного телесного угла. В работе разработаны методики реализации математического базиса пространственной фотометрии биологических сред по принципу определения интенсивности рассеяния по параллелям (кольцевым полосам) и меридианам (сечениям). Предложены схемотехнические решения двух- и восьмиканальной информационно-измерительных систем для пространственной фотометрии по сечениям, реализованные на уровне экспериментальных установок. Разработано программное обеспечение фотометрического параллельного анализа, позволяющее исследовать индикатрисы рассеяния по сечениям. Проведен анализ индикатрис рассеяния лазерного излучения толщинными образцами мышечных тканей на различных длинах волн и с разным размещением волокон. Осуществлен переход от индикатрисы рассеяния толщинных образцов к фактору анизотропии однократного рассеяния. Доказана идентичность экспериментально определенных величин оптических коэффициентов диффузного отражения и полного пропускания и определенных по результатам моделирования Монте-Карло с использованием усредненной по сечениям величины фактора анизотропии однократного рассеяния.

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Capitoli di libri sul tema "Scattering anisotropy factor"

Boothroyd, Andrew T. "Magnetic Scattering: General Properties". In Principles of Neutron Scattering from Condensed Matter, 185–212. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862314.003.0006.

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The basic theory of magnetic scattering is presented. A response function for magnetic scattering is defined, and expressed in terms partial response functions. The relation between the partial response functions and the correlation function for components of the magnetization is obtained, and the dynamical part of the partial reponse functions is linked via the fluctuation-dissipation theorem to the absorptive part of the generalized susceptibility. It is shown how the dipole approximation can be used to simply the magnetic scattering operator for localized electrons, and the magnetic form factor is introduced. Examples of the use of the dipole magnetic form factor, as well as more general anisotropic magnetic form factors, are given. A comparison with the X-ray atomic form factor is given. Various sum rules for the magnetic response function and generalized susceptibility are obtained.

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Boothroyd, Andrew T. "Practical Aspects of Neutron Scattering". In Principles of Neutron Scattering from Condensed Matter, 343–404. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862314.003.0010.

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In this chapter, aspects of the planning and optimization of a neutron scattering experiment are covered, including attenuation, multiple scattering, data normalization, counting statistics, resolution, corrections for polarization analysis, and spurions. Practical aspects of diffraction experiments are described, including instrumentation, Rietveld refinement, anisotropic displacement parameters, the Ewald sphere construction, Lorentz factors, extinction and multiple scattering. Practical aspects of spectroscopy are also described, including triple-axis, time-of-flight and backscattering spectrometers, direct and indirect geometry, and some specific points arising in time-of flight inelastic scattering.

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Chimenti, Dale, Stanislav Rokhlin e Peter Nagy. "Measurement of Scattering Coefficients". In Physical Ultrasonics of Composites. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195079609.003.0012.

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In the previous chapters, we saw how waves in composites behaved under various circumstances, depending on material anisotropy and wave propagation direction. The most important function that describes guided wave propagation, and the plate elastic behavior on which propagation depends, is the reflection coefficient (RC) or transmission coefficient (TC). More generally, we can call either one simply, the scattering coefficient (SC). It is clear that the elastic properties of the composite are closely tied to the SC, and in turn the scattering coefficient determines the dispersion spectrum of the composite plate. Measuring the SC provides a route to the inference of the elastic properties. To measure the SC, we need only observe the reflected or transmitted ultrasonic field of the incident acoustic energy. In doing so, however, the scattered ultrasonic field is influenced by several factors, both intrinsic and extrinsic. Clearly, the scattered ultrasonic field of an incident acoustic beam falling on the plate from a surrounding or contacting fluid will be strongly influenced by the RC or TC of the plate material. The scattering coefficients are in turn dependent on the plate elastic properties and structural composition: fiber and matrix properties, fiber volume fraction, layup geometry, and perhaps other factors. These elements are not, however, the only ones to determine the amplitude and spatial distribution of energy in the scattered ultrasonic field. Extrinsic factors such as the finite transmitting and receiving transducers, their focal lengths, and their placement with respect to the sample under study can make contributions to the signal as important as the SC itself. Therefore, a systematic study of the role of the transducer is essential for a complete understanding and correct interpretation of acoustic signals in the scattered field. The interpretation of these signals leads ultimately to the inference of composite elastic properties. As we pointed out in Chapter 5, the near coincidence under some conditions of guided plate wave modes with the zeroes of the reflection coefficient (or peaks in the transmission coefficient) has been exploited many times to reveal the plate’s guided wave mode spectrum.

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Hayati Raad, Shiva, e Zahra Atlasbaf. "Dyadic Green’s Function for Multilayered Planar, Cylindrical, and Spherical Structures with Impedance Boundary Condition". In Electromagnetic Wave Propagation for Industry and Biomedical Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.95834.

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The integral equation (IE) method is one of the efficient approaches for solving electromagnetic problems, where dyadic Green’s function (DGF) plays an important role as the Kernel of the integrals. In general, a layered medium with planar, cylindrical, or spherical geometry can be used to model different biomedical media such as human skin, body, or head. Therefore, in this chapter, different approaches for the derivation of Green’s function for these structures will be introduced. Due to the recent great interest in two-dimensional (2D) materials, the chapter will also discuss the generalization of the technique to the same structures with interfaces made of isotropic and anisotropic surface impedances. To this end, general formulas for the dyadic Green’s function of the aforementioned structures are extracted based on the scattering superposition method by considering field and source points in the arbitrary locations. Apparently, by setting the surface conductivity of the interfaces equal to zero, the formulations will turn into the associated problem with dielectric boundaries. This section will also aid in the design of various biomedical devices such as sensors, cloaks, and spectrometers, with improved functionality. Finally, the Purcell factor of a dipole emitter in the presence of the layered structures will be discussed as another biomedical application of the formulation.

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Atti di convegni sul tema "Scattering anisotropy factor"

Choudhury, Niloy, e Steven L. Jacques. "Extracting scattering coefficient and anisotropy factor of tissue using optical coherence tomography". In SPIE BiOS, a cura di E. Duco Jansen e Robert J. Thomas. SPIE, 2012. http://dx.doi.org/10.1117/12.907401.

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Falconet, Julie, Raphael Sablong, Emmanuel Perrin, Franck Jaillon e Herve Saint-Jalmes. "Backscattered Stokes Vectors of Turbid Media: Anisotropy Factor and Reduced Scattering Coefficient Estimation". In 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2007. http://dx.doi.org/10.1109/iembs.2007.4352616.

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Xu, M., M. Alrubaiee, S. K. Gayen e R. R. Alfano. "Determination of light absorption, scattering and anisotropy factor of a highly scattering medium using backscattered circularly polarized light". In Biomedical Optics (BiOS) 2007, a cura di Steven L. Jacques e William P. Roach. SPIE, 2007. http://dx.doi.org/10.1117/12.703578.

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DeAngelo, Bianca, Grant Arzumanov, Patrick Shanley, Zhang Xu e M. Xu. "Determination of the scattering coefficient, the reduced scattering coefficient, and the anisotropy factor of tissue with differential interference contrast microscopy". In SPIE BiOS, a cura di Adam P. Wax e Vadim Backman. SPIE, 2012. http://dx.doi.org/10.1117/12.910457.

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Sullivan, Anthony, Anil Saigal e Michael A. Zimmerman. "Investigation of Structure-Property Relationships Between Crystal Orientation and Dielectric Behavior in Liquid Crystalline Polymers". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70628.

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Liquid crystalline polymers (LCP’s) make up a class of high performance materials, which derive favorable mechanical, chemical, and electrical characteristics from their long-range molecular order. The unique LCP microstructure gives rise to anisotropic bulk behavior and an understanding of the driving forces behind this morphology is essential to the design of manufacturing processes for isotropic material production. In this investigation, the crystalline orientation in injection molded LCP plaque samples was measured using 2D wide-angle x-ray scattering (WAXS). The direction of preferred alignment was observed from the WAXS scattering patterns and the degree of orientation in the material was quantified using an order parameter and an anisotropy factor. In addition, the dielectric constant was measured with respect to the mold direction (MD) and transverse direction (TD). To investigate the effects of processing on hierarchal structure in the material, and the resulting macroscopic properties, plaques of two different thicknesses were analyzed, both as-injection molded and with the skin layer mechanically removed. It is shown that preferred orientation along the shear direction in the LCP samples corresponds to dielectric anisotropy, and increasing sample thickness, or conversely, mechanically removing the shear aligned layer, results in a more isotropic dielectric response.

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Fukutomi, D., K. Ishii e K. Awazu. "Determination of scattering coefficient considering wavelength and absorption dependence of anisotropy factor measured by polarized beam for biological tissues". In SPIE/OSJ Biophotonics Japan, a cura di Takashige Omatsu, Yoshio Hayasaki, Yusuke Ogura, Yasuyuki Ozeki e Seigo Ohno. SPIE, 2015. http://dx.doi.org/10.1117/12.2203194.

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Sullivan, Anthony, Anil Saigal e Michael A. Zimmerman. "Structure-Property Relationships Between Morphological Anisotropy and Mechanical, Thermal, and Dielectric Behavior in Liquid Crystal Polymers". In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11608.

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Abstract Liquid crystal polymers (LCPs) form a class of high-performance plastics that exhibit comparable mechanical, chemical, and electrical characteristics to engineering metals and ceramics arising from their mesoscopic ordering. The unique hierarchal LCP microstructure leads to anisotropic bulk behavior and an understanding of the development of this morphology during manufacturing, as well as the subsequent effect on polymer properties, is essential to the design of isotropic material manufacturing processes. In this investigation, the preferred orientation in injection molded LCP plaque samples was measured using wide-angle x-ray scattering (WAXS). The direction of preferred alignment was observed from the WAXS scattering patterns and the degree of orientation in the material was quantified using an anisotropy factor. In addition, the mechanical, thermal, and dielectric bulk behavior was measured with respect to the mold direction (MD) and transverse direction (TD). To investigate the effects of processing geometry on microstructural development, and the resulting macroscopic properties, plaques of three different thicknesses were analyzed. In addition, the influence of melt rheology was probed through the comparison of two different commercial LCP resins. It is shown that a strong correlation exists between material performance and both the bulk polymer texture and the individual regimes of the hierarchal structure. The effects of processing geometry and polymer rheology also demonstrate the structure-property-processing dynamics at work in injection molded LCPs.

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Hunter, Brian, e Zhixiong Guo. "Improved Treatment of Anisotropic Scattering for Ultrafast Radiative Transfer Analysis". In ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/mnhmt2013-22006.

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The necessity of conserving both scattered energy and asymmetry factor for ballistic incidence after either FVM or DOM discretization is convincingly shown by analyzing ultrafast laser radiative transfer in a cubic enclosure housing a participating medium. A phase-function normalization technique introduced previously by the present authors to correct for non-conservation of energy and asymmetry factor in diffuse radiant energy scattering is applied to scattering of ballistic incidence for the first time in 3-D FVM/DOM in order to improve treatment of anisotropic scattering through reduction of angular false scattering errors. Treatment of only the diffuse radiation will not conserve ballistic properties if the direction of ballistic incidence differs from a predetermined discrete direction. Our ultrafast radiative transfer predictions generated using the FVM and DOM are compared to benchmark Monte Carlo predictions in the literature to gauge accuracy and to illustrate the necessity of ballistic phase-function normalization. Additionally, numerical predictions of energy deposition in a tissue-phantom medium are analyzed to further clarify the importance of accurate numerical predictions. It is shown that the addition of proper ballistic phase-function treatment greatly improves predicted heat fluxes and energy deposition for anisotropic scattering and for situations where accurate numerical modeling is crucial.

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Hunter, Brian, e Zhixiong Guo. "A New Phase Function Normalization Approach for Radiative Transfer Analysis in Highly Anisotropic Scattering Media". In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63664.

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A new phase function normalization approach is applied to both the DOM and FVM for predicting radiative heat transfer in an extreme condition — highly anisotropic scattering media. Previous attempts to normalize the DOM result in a distortion of the overall phase function asymmetry factor. The splitting of each solid angle into numerous sub-angles in the FVM is shown to also produce a lack of conservation of asymmetry factor, even though scattered energy is conserved. The current normalization technique is crafted such that scattered energy and asymmetry factor are accurately conserved after both DOM and FVM discretization. The change in scattering effect when asymmetry factor is not conserved is examined for both methods. Wall flux profiles generated by DOM with old and new normalization techniques as well as FVM with and without phase function normalization are compared to isotropic scaling law profiles to gauge the accuracy of the techniques. The effects of changes in both optical thickness and scattering albedo are investigated. It is found that the current normalization approach vastly improves accuracy of flux profiles. The current procedure also greatly decreases FVM convergence time by eliminating the need for large amounts of solid angle splitting.

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Boumaza, Mohamed. "Crystallographic Orientation Effect On Hole Polar Optical Phonon Scattering Rates in Thin Gaas/Alxga1-Xas Quantum Wells". In 2nd International Conference on Research in Science, Engineering and Technology. Acavent, 2019. http://dx.doi.org/10.33422/2nd.icrset.2019.11.784.

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We report on hole polar optical phonon scattering processes in thin GaAs/AlxGa1-xAs quantum wells grown in various crystallographic directions, such as [001], [110]. Using the dielectric continuum model we focus on how the different scattering processes of holes with interface phonon modes depend on the initial hole energy. In our work, we use the Luttinger-Kohn (LK) 6×6 k.p Hamiltonian with the envelope function approximation, from which we compute numerically the electronic structure of holes for a thin quantum well sustaining only one bound state for each type of hole. Due to mixing between the heavy, light, and split off bands, hole subbands exhibit strong nonparabolicity and important warping that have their word to say on physical properties. Detailed and extensive calculations that the rates for intra-subband scattering processes differ significantly from those of bulk GaAs because of quantization and reduced dimensionality. Moreover, the study of scattering as a function of hole energy shows that the trend of the scattering rates is governed mostly by i) overlap integrals and ii) the density of the final states to which the hole scatters. The influence of warping, in the hole energy dispersion, on the phonon scattering rates is also explored and found to be important when the initial hole energy is high. Our calculations show evidence of strong anisotropy in the scattering rates especially for processes involving the heavy hole subband, which anisotropy is in fact quite important and far from being negligible. However, strain effect can reduce scattering rates.

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