Tesis sobre el tema "Multi-spectral method"

Fluctuations in the solar wind characteristics such as speed, temperature, magnetic strength and density are associated with pulsations in the magnetosphere. Coherent magnetohydrodynamic waves in the solar wind may sometimes be a direct source of periodic pulsations in the frequency interval 1 to 7 mHz in the magnetosphere. In studies of the solar wind and the way its variation affects the magnetosphere, the significance of different frequency components and their signal fonn are of interest. Spectral analysis and signal reconstruction are important tools in these studies and in this report the MultiTaper Method (MTM) of spectral analysis is compared to the "classic" method, using the Hanning window and Fourier transformation. The MTM-SSA toolkit, developed by Department of Atmospheric Science at the University of California, is used to ascertain whether the MTM might be suitable. The advantages of the MTM are reduced information loss in analysed data sequences and statistical support in the analysis. Besides the compared methods of spectral analysis, an attempt has been made to test the validity of the adiabatic law, assumed as the relation between the thermal pressure and the density in the solar wind plasma. It was unfortunately difficult to estimate the gamma parameter of this relation, possibly due to the turbulent behaviour of the solar wind.

Inledning:Oral cancer är ett allvarligt tillstånd med hög dödlighet, särskilt vid sen diagnostisering. Brasilien är ett av de länder i världen som har högst prevalens och dödlighet i oral cancer och det är den femte vanligaste cancerformen I landet. Ett hjälpmedel för tidig diagnostisering är önskvärd.Syfte:Att utvärdera skillnaden i diagnostisk tillförlitlighet mellan konventionell oral undersökning och användning av multispektralt ljus (Identafi®) som en metod för tidig upptäckt av potentiellt maligna och maligna lesioner i munslemhinnan i en brasiliansk befolkning.Material och metod:Screening av en befolkning med förhöjd risk för att utveckla oral cancer i Goiânia, Goiás, Brasilien, för att upptäcka potentiellt maligna (PML) eller maligna lesioner (ML). Patienter med misstänkta PML eller ML upptäckta under screeningen undersöktes med multispektralt ljus (Identafi®). Tre oberoende observatörer genomförde bedömning med Identafi® och slutgiltig beslut avseende PML/ML togs i konsensus. Biopsier användes som diagnostisk referensstandard. Interobservatörs överensstämmelse beräknades som procentuell överensstämmelse och kappa-värde (κ).Resultat:Undersökning med Identafi® genererade tolv biopsier. Resultaten blev tre sant positiva, fem falskt positiva, två sant negativa och noll falskt negativa. Sensitiviteten beräknades till 0,29. Specificiteten var inte möjlig att beräkna, då det inte fanns några falska negativa resultat. Interobservatörs överensstämmelse för par av observatörer varierade mellan 78-86% och κ-värden mellan 0,46-0,60.Slutsats:Slutsatsen är att multispektralt ljus, Identafi® inte har inga fördelar jämfört med konventionell klinisk undersökning i fråga om diagnostisk träffsäkerhet för PML eller ML. Dock kan det vara till hjälp för en tandläkare eller oral kirurg som stöd i sitt beslutsfattande. Det kan också hjälpa kirurgen att ta en biopsi från det mest misstänkta delen av lesionen. Det finns inte tillräckligt publicerade studier som tyder på att Identafi® kan skilja mellan normal slemhinna och PML eller ML och denna studie bekräftar detta. Användning av Identafi® som ett hjälpmedel vid screening och undersökning för PML eller ML behöver utredas ytterligare, men baserat på denna studie kan Identafi® inte rekommenderas.
Introduction: Oral cancer is a severe condition with high mortality rate, in particular if diagnosed late. Brazil is one of the countries in the world with high prevalence and mortality from oral cancer and it is the fifth most common cancer there. An aid in early detection of oral cancer as an adjunct to health promotion is desirable.Purpose:The aim of this study was to evaluate the diagnostic accuracy of conventional oral examination and the use of multi spectral light (Identafi®) as an approach for early detection of potentially malignant or malignant lesions in the oral mucosa in a Brazilian population.Material and method:Screening of high-risk population in Goiania, Goias, Brazil, for oral potentially malignant lesions (PML) or malignant lesions (ML) as a selection phase. Patients collected from the screening were examined with multi spectral light (Identafi®) to evaluate diagnostic accuracy. Three observers independently assessed all lesions with Identafi® and the final decision if a lesion was present was taken in consensus. Inter observer agreement was calculated as overall agreement and as kappa value (κ). Biopsies were used as diagnostic reference standard.Results:Identafi® generated, from twelve biopsies, three true positive, five false positive, two true negative and zero false negative. Sensitivity was calculated to 0.29 and specificity was not possible to calculate since there were no false negative results.Inter observer agreement for the use of Identafi® was calculated as overall agreement and as kappa value (κ). The overall agreement for the three pairs of observers varied between 78-86% and κ-values between 0.46 and 0.60.Conclusion:The conclusion of this study is that Identafi® does not have any benefits over conventional oral examination in diagnostic accuracy for potentially malignant or malignant lesions in the oral mucosa. It might, however, be an aid for a dentists or oral surgeons that are unsure whether to take a biopsy or not. It can also aid the surgeon when taking a biopsy to take the most suspicious part of the lesion. There are not enough published evidence that Identafi® can discriminate between normal mucosa and PML or ML, and this study confirms previous results. The use of Identafi® as an aid in screening and examination for PML or ML needs further investigation.

Abstract Cognitive Radio (CR) improves the efficiency of spectrum utilization by allowing non- licensed users to utilize bands when not occupied by licensed users. In this thesis, we address several challenges currently limiting the wide use of cognitive radios. These challenges include identification of unoccupied bands, energy consumption and other technical challenges. Improved accuracy edge detection techniques are developed for CR to mitigate both noise and estimation error variance effects. Next, a reduced complexity Simplified DFT (SDFT) is proposed for use in CR. Then, a sub-Nyquist rate A to D converter is introduced to reduce energy consumption. Finally, a novel multi-resolution PSD estimation based on expectation-maximization algorithm is introduced that can obtain a more accurate PSD within a specified sensing time.

Ce mémoire est constitué de deux parties relativement indépendantes, dont la première partie porte sur les méthodes de mesure de température par méthodes Multi-Spectrales (pyrométrie optique passive), et la seconde sur la Caractérisation Thermique à haute température par transformations intégrales de matériaux orthotropes. Dans chacune de ces deux parties, les méthodes/modèles développés ont été traités du point de vue théorique, numérique, et expérimental. Dans la partie multi-spectrale, une méthode de mesure de température permettant de prendre en compte les variations spectrales de la chaine de mesure globale (incluant l’émissivité) a été présentée. De plus, une méthode de détermination des longueurs d’ondes optimales au sens de la minimisation de l’écart-type sur la température, a été développée. Enfin, il a également été montré que les longueurs d’ondes optimales pour les mesures mono-spectrales et bi-spectrales pouvaient être déterminées à l’aide de lois analogues à la loi de déplacement de Wien. Dans la partie Caractérisation Thermique, différentes méthodes et modèles ont été développés. Les méthodes proposées effectuent l’estimation des diffusivités longitudinales et transversales sur l’ensemble des harmoniques simultanément. De plus, ces méthodes permettent de s’affranchir du couplage thermique dû à la présence d’un porte-échantillon, et/ou d’effectuer des mesures de diffusivités pseudo-locales, en injectant comme conditions aux limites les informations expérimentales obtenues par caméra infrarouge. Enfin, les notions de corrélation entre les paramètres et de durée d’exploitabilité des harmoniques ont également été abordées
This thesis consists of two relatively independent parts, the first part focuses on methods of temperature measurement using Multi-Spectral (passive optical pyrometry) methods, and the second on the Thermal Characterization by integral transforms at high temperature of orthotropic materials. In each of these two parts, methods / models developed were treated from a theoretical point of view, numerical and experimental. In the multi-spectral part, a method of temperature measurement to take into account a spectral variation of the overall measurement chain (including the emissivity) was introduced. Moreover, a method of determining the optimal wavelengths in the sense of minimizing the standard deviation of temperature, has been developed. Finally, it has also been shown that the optimal wavelengths for mono-spectral and bi-spectral measurements could be determined with similar laws to Wien's displacement law. In the Thermal Characterization part, different methods and models have been developed. The proposed methods perform the estimation of longitudinal and transverse diffusivities on all harmonics simultaneously. Furthermore, they allow overcoming the thermal coupling due to the presence of a sample holder, and / or making pseudo-local measurements of diffusivities. Finally, the concepts of correlation between parameters and duration of harmonics exploitability were also discussed.This thesis consists of two relatively independent parts, the first part focuses on methods of temperature measurement using Multi-Spectral (passive optical pyrometry) methods, and the second on the Thermal Characterization by integral transforms at high temperature of orthotropic materials. In each of these two parts, methods / models developed were treated from a theoretical point of view, numerical and experimental. In the multi-spectral part, a method of temperature measurement to take into account a spectral variation of the overall measurement chain (including the emissivity) was introduced. Moreover, a method of determining the optimal wavelengths in the sense of minimizing the standard deviation of temperature, has been developed. Finally, it has also been shown that the optimal wavelengths for mono-spectral and bi-spectral measurements could be determined with similar laws to Wien's displacement law. In the Thermal Characterization part, different methods and models have been developed. The proposed methods perform the estimation of longitudinal and transverse diffusivities on all harmonics simultaneously. Furthermore, they allow overcoming the thermal coupling due to the presence of a sample holder, and / or making pseudo-local measurements of diffusivities. Finally, the concepts of correlation between parameters and duration of harmonics exploitability were also discussed

Lighting installations are usually static and based on long-standing visual indicators such as colour temperature, colour rendering, and illuminance values. However, we now know that spectral variations in light elicit non-visual effects via a distinct pathway in our brain, and it is important for designers and architects to take these into account: light influences our mood, modulates our attention, can suppress the production of melatonin and can shift our circadian rhythms. Considering all the spectral aspects of light is the initial step towards designing healthier environments that are both pleasant and respectful to our biology. Multi-channel LED light engines can provide the core technology for a truly spectral lighting design, thereby enabling wider applications of light with different purposes. This dissertation aims at facilitating this transition by delivering cost-effective multi-channel LED light engines capable of generating arbitrary spectral shapes. In the first part of this work, we develop a light engine for a research-oriented market and explore novel designs and solutions for an advanced industrial device aimed at tackling a more general lighting market. These two efforts led to the development of two optically and spectrally different devices: the SPECTRA TUNE LAB light engine (with an on-board spectrometer and ten different LED channels), and the VEGA 07 light engine (equipped with a colour sensor and seven different LED channels). Second, to generate arbitrary spectral shapes, we perform an extensive study on different heuristic algorithms implemented directly in the microcontroller of the light engine as well as in its control software. We show that the simulated annealing algorithm provides fast computation times with excellent spectral fidelity. Third, we develop two types of optical feedback controllers with different light sensors to prevent temperature-driven colour and spectral shifts, and the wear-out of the LEDs. Both these sensors, i.e. the spectrometer in the SPECTRA TUNE LAB and the colour sensor in the VEGA 07, are used to ensure high precision and accuracy of the emitted light at all times and for any kind of target spectrum. Finally, we demonstrate the ways in which these devices can be used for different applications, thereby verifying the huge advantages and added value of this technology as compared to traditional lighting systems. Our developed light engines were installed in the intensive care units of two hospitals (Hospital Vall d'Hebron and Hospital Clínic in Barcelona), in office settings (ARUP's office in London), and 24/7 control rooms (Repsol's refinery control room in Tarragona), among others.
Les instal·lacions dil·luminació solen ser estàtiques i basades en indicadors visuals clàssics com la temperatura de color, la representació dels colors o els nivells d'il·luminació. Tanmateix, avui sabem que la llum també té una funció que no és propiament visual i que els arquitectes i dissenyadors haurien de començar a tenir en compte: la llum pot influir en el nostre estat d'ànim, modular la nostra atenció, regular la producció de melatonina o modificar els ritmes circadiaris. Tenir en compte totes les propietats espectrals de la llum és el primer pas per dissenyar entorns més sans i respectuosos amb la nostra biologia. Així, el disseny i desenvolupament de noves fonts de llum LED multicanal assequibles serà la tecnologia que permetrà un autentic canvi de paradigma espectral i començar a utilitzar la llum per a múltiples aplicacions. Aquest treball té com a objectiu facilitar aquesta transició proporcionant fonts de llum LED amb capacitat per generar qualsevol tipus de forma espectral. En una primera part, hem desenvolupat un sistema d'il·luminació multicanal orientat a un mercat d'investigació i recerca, i hem explorat nous dissenys i solucions per a un dispositiu més industrial amb l'objectiu de penetrar al mercat d'il·luminació general. Els dos esforços s'han materialitzat en dos dispositius òpticament i espectralment diferents: el sistema de llum SPECTRA TUNE LAB (amb un espectròmetre a l'interior i 10 canals LED diferents) i el sistema de llum VEGA 07 (amb un colorímetre i 7 canals LED diferents). En segon lloc, per poder crear qualsevol tipus de forma espectral, hem estudiat diferents algorismes heurístics implementats directament al micro-controlador de la lluminària o en un programari extern. L'algorisme desenvolupat de simulated annealing ha resultat ser el més ràpid amb una fidelitat espectral excel·lent. En tercer lloc, hem desenvolupat dos tipus de controladors òptics de llaç tancat amb dos sensors de llum diferents per evitar canvis de color i canvis espectrals degut a increments de la temperatura o degradació dels LEDs. Ambdós sensors, l'espectròmetre per l'SPECTRA TUNE LAB i el colorímetre pel VEGA 07, s'utilitzen per assegurar que la llum emesa romangui precisa i estable en tot moment, per a qualsevol espectre que vulguem generar. Finalment, demostrem com aquests dispositius es poden utilitzar per a diferents aplicacions oferint grans avantatges en comparació amb sistemes tradicionals. El nostre sistema d'il·luminació s'ha instal·lat a la unitat de cures intensives dhospitals (a l'Hospital Vall d'Hebron i a l'Hospital Clínic, a Barcelona), en entorns d'oficina (a ARUP, a Londres) o en sales de control 24 hores (a la sala de control de la refineria de Repsol, a Tarragona), entre d'altres
Enginyeria òptica

This thesis considers new methods that exploit recent developments in computer technology to address three extant problems in the area of Finance and Econometrics. The problem of Asian option pricing has endured for the last two decades in spite of many attempts to find a robust solution across all parameter values. All recently proposed methods are shown to fail when computations are conducted using standard machine precision because as more and more accuracy is forced upon the problem, round-off error begins to propagate. Using recent methods from numerical analysis based on multi-precision arithmetic, we show using the Mathematica platform that all extant methods have efficacy when computations use sufficient arithmetic precision. This creates the proper framework to compare and contrast the methods based on criteria such as computational speed for a given accuracy. Numerical methods based on a deformation of the Bromwich contour in the Geman-Yor Laplace transform are found to perform best provided the normalized strike price is above a given threshold; otherwise methods based on Euler approximation are preferred. The same methods are applied in two other contexts: the simulation of stable distributions and the computation of unit root densities in Econometrics. The stable densities are all nested in a general function called a Fox H function. The same computational difficulties as above apply when using only double-precision arithmetic but are again solved using higher arithmetic precision. We also consider simulating the densities of infinitely divisible distributions associated with hyperbolic functions. Finally, our methods are applied to unit root densities. Focusing on the two fundamental densities, we show our methods perform favorably against the extant methods of Monte Carlo simulation, the Imhof algorithm and some analytical expressions derived principally by Abadir. Using Mathematica, the main two-dimensional Laplace transform in this context is reduced to a one-dimensional problem.

Cette étude porte sur la mesure de la température à l’échelle microscopique par voie optique dans la gamme UV-visible par comptage de photons à l’aide d’un PMT refroidi. À partir des avantages et des inconvénients de chaque technique existante, la première partie permet de comprendre les orientations de nos travaux. Le Second Chapitre montre et insiste sur l’intérêt de travailler aux courtes longueurs d’onde (limite de diffraction, précision sur la mesure...), d’utiliser la méthode multi-spectrale pour s’affranchir de paramètres inconnus (e.g. l’émissivité) en choisissant judicieusement les longueurs d’onde de travail, ainsi que les lois statistiques classiques pour mesurer le flux photonique sachant son émission aléatoire. Le Chapitre Trois présente le banc de mesure (microscope optique, système de mesure du flux photonique...) et une attention toute particulière est portée sur la conception des éléments chauffants servant à l’étalonnage. Le Quatrième Chapitre présente les résultats en températures obtenues à l’aide des lois statistiques. Ils valident le bon fonctionnement du dispositif, la mise au point de la zone microscopique, et l’intérêt de bien modéliser les filtres monochromatiques. Enfin, des améliorations sur la précision de la mesure (réseau de diffraction, analyseur multi-canal) et pour mesurer des températures plus faibles (LIF, méthode corrélation temporelle) sont présentées dans le Cinquième Chapitre
The aim of this study is to measure microscale temperature by optical way in the UV-visible range by photons counting using a cooled PMT. From the existing techniques advantages and disadvantages, this first part allows to understand the choices of this study. The second part shows and underlines the interest in working in short wavelengths (diffraction limit, measurement accuracy), in using the multi-spectral method to get rid of unknown parameters (e.g. emissivity) by choosing judicious working wavelengths, as well as the statistic laws to measure the photonic flux knowing its random emission. The third chapter presents the optical bench (optical microscope, photonic flux measurement facility…). A particularly attention is given to the design of the heated elements, which allow to calibrate the facility. The fourth part exposes the temperature results obtained through statistic laws. They validate the well-running of the facility, the microscopic area focusing, and the interest to model correctly the filters. Finally, measurement accuracy improvements (diffraction grating, multi-channel analyzer) and lower temperature measurement techniques (LIF, time-correlated method) are presented in the fifth part

Fusion of images captured from different viewpoints is a well-known challenge in computer vision with many established approaches and applications; however, if the observations are captured by sensors also separated by wavelength, this challenge is compounded significantly. This dissertation presents an investigation into the fusion of visible and thermal image information from two front-facing sensors mounted side-by-side. The primary focus of this work is the development of methods that enable us to map and overlay multi-spectral information; the goal is to establish a combined image in which each pixel contains both colour and thermal information. Pixel-level fusion of these distinct modalities is approached using computational stereo methods; the focus is on the viewpoint alignment and correspondence search/matching stages of processing. Frequency domain analysis is performed using a method called phase congruency. An extensive investigation of this method is carried out with two major objectives: to identify predictable relationships between the elements extracted from each modality, and to establish a stable representation of the common information captured by both sensors. Phase congruency is shown to be a stable edge detector and repeatable spatial similarity measure for multi-spectral information; this result forms the basis for the methods developed in the subsequent chapters of this work. The feasibility of automatic alignment with sparse feature-correspondence methods is investigated. It is found that conventional methods fail to match inter-spectrum correspondences, motivating the development of an edge orientation histogram (EOH) descriptor which incorporates elements of the phase congruency process. A cost function, which incorporates the outputs of the phase congruency process and the mutual information similarity measure, is developed for computational stereo correspondence matching. An evaluation of the proposed cost function shows it to be an effective similarity measure for multi-spectral information.

Land cover change detection in urban areas provides valuable data on loss of forest and agricultural land to residential and commercial development. Using Landsat 5 Thematic Mapper (1991) and Landsat 7 ETM+ (2000) imagery of Gwinnett County, GA, change images were obtained using image differencing of Normalized Difference Vegetation Index (NDVI), principal components analysis (PCA), and Tasseled Cap-transformed images. Ground truthing and accuracy assessment determined that land cover change detection using the NDVI and Tasseled Cap image transformation methods performed best in the study area, while PCA performed the worst of the three methods assessed. Analyses on vegetative and vegetation changes from 1991- 2000 revealed that these methods perform well for detecting changes in vegetation and/or vegetative characteristics but do not always correspond with changes in land use. Gwinnett County lost an estimated 13,500 hectares of vegetation cover during the study period to urban sprawl, with the majority of the loss coming from forested areas.

Thesis (M.A.)--Georgia State University, 2005.
Title from title screen. Zhi-Yong Yin, committee chair; Paul Knapp, Truman Hartshorn, committee members. Electronic text (135 p. : col. ill., col. maps)) : digital, PDF file. Description based on contents viewed Aug. 2, 2007. Includes bibliographical references (p. 125-133).

La modélisation numérique de la propagation des ondes sismiques fait partie des études principales sur le calcul du mouvement sismique basées sur de différents schèmes numériques. La prise en compte du comportement nonlinéaire du sol est consideré désormais très important afin de pouvoir calculer la réponse du milieu cohéremment aux observations sous les sollications sismiques très fortes. En plus, le paramètre de pression interstitielle, qui pourrait emmener le sol aux phénomènes de liquéfaction, devient très important pour les sols saturés. Dans cette étude, dans un premier temps, la propagation des ondes sismiques est modelisée sur une composante (1C) dans les milieux linéaires et nonlinéaires en utilisant la méthode numérique des éléments spéctraux. Les rhéologies viscoélastique et nonlinéaire sont implementées par le méthode de technique des variables de mémoire et le modèle élastoplastique d’Iwan, respectivement. Ensuite, le modèle 1D - trois composantes (3C) est développé et une comparaison préalable sur l’effet de la considération des approches 1C et 3C est faite. L’effet de pression interstitielle est implementé dans le code 1D-3C et le site américain Wildlife Refuge Liquefaction Array (WRLA), qui a été frappé par le séisme de Superstition Hills en 1987 est étudié. Le changement de la réponse du sol sous les différents hypothèses de rhéologie du sol et de mouvement d’entrée est étudié. Le mouvement calculé est noté d’être amplifié pour les basses fréquences et atténué pour les hautes fréquences en raison de l’excès de pression interstitielle dans les sols liquéfiables. Par ailleurs, le sol devient plus nonlinéaire sous le chargement triaxial dans l’approche 3C et plus dilatant dû à la nonlinéarite élevée. En dépit de la similitude entre les accélérations et les vitesses en surface des approches 1C et 3C, une importante différence dans le déplacement en surface entre les deux approches est notée. Les analyses sont répétées pour deux sites japonais Kushiro Port et Onahama Port, qui ont été influencés par le séisme de Kushiro-Oki en 1993 et le séisme de la côte Pacifique de Tohoku en 2011, respectivement. Il a été montré que les changements apportés par la nonlinéarite ne sont pas identiques dans toute la gamme de fréquence concernée et l’influence du comportement des sols non-cohésives sur la propagation des ondes sismiques dépend fortement des propriétés du modèle et des conditions de chargement. Dernièrement, le code SEM est avancé en 2D en considerant les mêmes modèles implementés en 1D-3C pour la nonlinéarite du sol et les effets de pression interstitielle. Le code SEM 2D est mis en application dans un modèle de bassin sédimentaire dont la géometrie est assymmétrique et le profile du sol est composé des couches possédant différentes propriétés nonlinéaires. Le modèle est étudié par les analyses totale et effective pour les propagation des ondes P-SV et SH. La differentiation du mouvement calculé en surface est très importante sous les chargements avec les signaux d’entrée synthétique et réel. L’analyse effective résulte en plus de déformations dans les couches superficielles par rapport à l’analyse totale.De plus, la durée de propagation des ondes augmente à l’intérieur du bassin et les reflections aux frontières de bassin-rocher entraînent plus de nonlinéarite dans les coins du bassin. Cette thèse révèle la possibilité de la modélisation du comportement nonlinéaire du sol en prenant en compte l’effet de pression interstitielle dans les études de la propagation des ondes sismiques en couplant les modèles différents avec la méthode des éléments spéctreaux. Ces analyses contribuent à l’identification et la compréhension des phénomènes majeures qui se déroulent dans les couches superficielles en respectant les conditions locales et les mouvements d’entrées, ce quirend ce travail très important pour les études spécifiques de sites
Numerical modeling of seismic wave propagation has been a major topic on ground motion studies using a number of different numerical integration schemes. The consideration of soil nonlinearity holds an important place in order to achieve simulations consistent with real observations for strong seismic shaking. Additionally, in the presence of strong ground motion in saturated soils, pore pressure becomes an important parameter to take into account for related phenomena such as flow liquefaction and cyclic mobility. In this study, first, one component (1C) - seismic wave propagation is modeled in linear and nonlinear media in 1D based on the spectral element numerical method. Viscoelastic and nonlinear soil rheologies are implemented by use of the memory variables technique and Iwan’s elastoplastic model, respectively. Then, the same study is extended to a 1D - three component (3C) model and a preliminary comparison on the effect of using 1C and 3C approaches is made. Then, the influence of excess pore pressure development is included in the 1D-3C model and the developped numerical model is applied to realistic case on the site of Wildlife Refuge Liquefaction Array (USA) which is affected by the 1987 Superstition Hills event. The ground motion modification for different assumptions of the soil rheology in the media and different input motions is studied. The calculated motion is found to be amplified on low frequency and damped in high frequency range due to excess pore pressure development. Furthermore, the soil is found to be more nonlinear under triaxial loading in 3C approach and more dilative due to higher nonlinearity. Despite the similitude in surface acceleration and velocity results, significant differences in surface displacement results of 1C and 3C approaches are remarked. Similar analyses are performed on two Japanese sites Kushiro Port and Onahama Port, which are influenced by the 1993 Kushiro-Oki and the 2011 off the Pacific coast of Tohoku earthquakes, respectively. It has been shown that the nonlinearity-related changes are not homogeneous all over the concerned frequency band and the influence of cohesionless soil behavior on wave propagation is highly dependent on model properties and loadingconditions. Lastly, the 2D SEM code is developped by taking into account soil nonlinearity and pore pressure effects similary to 1D-3C SEM code. The developped 2D SEM code is applied to a 2D sedimentary basin site where the basin geometry is asymmetrical and soil profile consists of layers with different nonlinearity properties. Total and effective stress analyses are performed on the 2D basin for P-SV and SH zave propagation models. The calculated surface motion is shown to differ significantly under synthetic and realistic input motion loading conditions and the resultant deformation in superficial layers is found to be very high in effective stress analysis compared to total stress analysis. Also, wave propagation takes longer time inside basin media and the reflections on bedrock-basin boundaries lead the soil in basin edges to higher nonlinearity. This study shows the possibility of modeling nonlinear soil behavior including pore pressure effects in seismic wave propagation studies by coupling different models with spectral element method. These analyses help identifying and understanding dominant phenomena occurring in superficial layers, depending on local conditions and input motions. This is of great importance for site-specific studies

In this work, we proposed a spectral integral method (SIM)-spectral element method (SEM)- finite element method (FEM) domain decomposition method (DDM) for solving inhomogeneous multi-scale problems. The proposed SIM-SEM-FEM domain decomposition algorithm can efficiently handle problems with multi-scale structures,

by using FEM to model electrically small sub-domains and using SEM to model electrically large and smooth sub-domains. The SIM is utilized as an efficient boundary condition. This combination can reduce the total number of elements used in solving multi-scale problems, thus it is more efficient than conventional FEM or conventional FEM domain decomposition method. Another merit of the proposed method is that it is capable of handling arbitrary non-conforming elements. Both geometry modeling and mesh generation are totally independent for different sub-domains, thus the geometry modeling and mesh generation are highly flexible for the proposed SEM-FEM domain decomposition method. As a result, the proposed SIM-SEM-FEM DDM algorithm is very suitable for solving inhomogeneous multi-scale problems.

Dissertation

碩士
國立中央大學
電機工程研究所
95
Magnetic Resonance Imaging (MRI) is a useful medical instrument in medical science. It provides unparallel capability of revealing soft tissue characterization as well as 3-D visualization and proposes the diagnosis without needing to intrude into the human body. MRI produces a sequence of multiple spectral images of tissues with a variety of contrasts, but the multi-spectral images cannot be conveniently used to be a pathology diagnosis correctly. In general, we need to transform the multi-spectral images to an enhanced image which is easier to be used for doctor’s clinical diagnosis. One of the potential applications of MRI in clinical practice is the brain parenchyma classification. In this thesis, we first present a feature selection method called Target Generation Process (TGP) and the TGP generates a set of potential targets from an unknown background. Let the targets be the training data for the classifiers of Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM), respectively, such that the classification and segmentation for the MR images are achieved. The algorithm combining TGP and LDA (or SVM) is called Unsupervised Linear Discriminant Analysis (ULDA) (or Unsupervised Support Vector Machine (USVM)). Finally, the effectiveness of ULDA and USVM in target classification is evaluated by several MRI images experiments. In order to further evaluate its performance, they are compared with the method of Fuzzy c-mean. Several experiment results show that the ULDA and USVM have the better effective segmentation for multi-spectral MR images.

Thesis (Ph. D.)--Florida State University, 2008.
Advisor: David A. Kopriva, Florida State University, College of Arts and Sciences, Dept. of Mathematics. Title and description from dissertation home page (viewed July 9, 2008). Document formatted into pages; contains xii, 111 pages. Includes bibliographical references.

碩士
國立臺灣科技大學
色彩與照明科技研究所
106
The key point enabling multi-spectral LED lighting to be superior to the traditional lighting source is that multi-spectral LED lighting could create a suitable lighting environment by dimming for users in different occasions. However, under the long-term current driven, the effects of electricity and heat from LED Lighting would reduce optical power output and even lead to inconsistent light source decay, which results in color difference. In order to detect color difference of light source, spectrometer, a considerably accurate color detecting instrument, could identify changes in spectrum. Yet, in light of price and universality of spectrometer, the instrument is not a better choice. Therefore, the thesis utilizes two RGB color sensors as the device to perceive interior light source and ambient light. After color calibration, the sensor could get average ∆u’v’ less than 0.0015 and average illuminance error less than 10lux under various illuminance within the range of common mixed temperature (2000K-7000K) to detect color deviation of light. As the outcome of light source is beyond expectation, we would compensate light source via closed-loop control. The result implies that as differences of color or illuminance have reached certain errors, system can adjust automatically and keep producing light source output effectively. Moreover, by utilizing the way of control, measuring under warm, neutral and cool color temperatures could obtain illuminance errors with 2.2lux/5.6lux/5.3lux respectively and errors of color temperature only with 5.9K/12.2K and 11.9K. In terms of ambient detection, we classify characteristics of color sensor through collecting four kinds of light source with total twenty-four lighting conditions, thereby generating decision tree. Applying varied light sources chosen by decision tree into calibration matrix, color sensor could recognize lighting condition of interior environment. We, further, propose two modes where light supplement of multi-spectral LED lighting is applied. One of the modes could adjust illumination as color of ambient light alters, which can achieve the purpose of saving energy. The other could meet users’ demands by mingling ambient light in specific area. After calculating differences, the Du’v’ under the first mode is less than 0.0015 and DY is only 0.77%. Under the other mode, the Du’v’ is only 0.0017 and DY is merely 2.9%. The outcomes show that light supplement of multi-spectral LED lighting could achieve effective effect when applied into these two modes.

This thesis presents an efficient self-consistent Hybrid Spectral Ray Tracing (HSRT) technique for analysis and design of multi-scale sub-millimeter wave problems, where sub-wavelength features are modeled using rigorous methods, and complex structures with dimensions in the order of tens or even hundreds of wavelengths are modeled by asymptotic methods. Quasi-optical devices are used in imaging arrays for sub-millimeter and terahertz applications, THz time-domain spectroscopy (THz-TDS), high-speed wireless communications, and space applications to couple terahertz radiation from space to a hot electron bolometer. These devices and structures, as physically small they have become, are very large in terms of the wavelength of the driving quasi-optical sources and may have dimension in the tens or even hundreds of wavelengths. Simulation and design optimization of these devices and structures is an extremely challenging electromagnetic problem. The analysis of complex electrically large unbounded wave structures using rigorous methods such as method of moments (MoM), finite element method (FEM), and finite difference time domain (FDTD) method can become almost impossible due to the need for large computational resources. Asymptotic high-frequency techniques are used for analysis of electrically large quasi-optical systems and hybrid methods for solving multi-scale problems. Spectral Ray Tracing (SRT) has a number of unique advantages as a candidate for hybridization. The SRT method has the advantages of Spectral Theory of Diffraction (STD). STD can model reflection, refraction and diffraction of an arbitrary wave incident on the complex structure, which is not the case for diffraction theories such as Geometrical Theory of Diffraction (GTD), Uniform theory of Diffraction (UTD) and Uniform Asymptotic Theory (UAT). By including complex rays, SRT can effectively analyze both near-fields and far-fields accurately with minimal approximations. In this thesis, a novel matrix representation of SRT is presented that uses only one spectral integration per observation point and applied to modeling a hemispherical and hyper-hemispherical lens. The hybridization of SRT with commercially available FEM and MoM software is proposed in this work to solve the complexity of multi-scale analysis. This yields a computationally efficient self-consistent HSRT algorithm. Various arrangements of the Hybrid SRT method such as FEM-SRT, and MoM-SRT, are investigated and validated through comparison of radiation patterns with Ansoft HFSS for the FEM method, FEKO for MoM, Multi-level Fast Multipole Method (MLFMM) and physical optics. For that a bow-tie terahertz antenna backed by hyper-hemispherical silicon lens, an on-chip planar dipole fabricated in SiGe:C BiCMOS technology and attached to a hyper-hemispherical silicon lens and a double-slot antenna backed by silica lens will be used as sample structures to be analyzed using the HSRT. Computational performance (memory requirement, CPU/GPU time) of developed algorithm is compared to other methods in commercially available software. It is shown that the MoM-SRT, in its present implementation, is more accurate than MoM-PO but comparable in speed. However, as shown in this thesis, MoM-SRT can take advantage of parallel processing and GPU. The HSRT algorithm is applied to simulation of on-chip dipole antenna backed by Silicon lens and integrated with a 180-GHz VCO and radiation pattern compared with measurements. The radiation pattern is measured in a quasi-optical configuration using a power detector. In addition, it is shown that the matrix formulation of SRT and HSRT are promising approaches for solving complex electrically large problems with high accuracy. This thesis also expounds on new measurement setup specifically developed for measuring integrated antennas, radiation pattern and gain of the embedded on-chip antenna in the mmW/ terahertz range. In this method, the radiation pattern is first measured in a quasi-optical configuration using a power detector. Subsequently, the radiated power is estimated form the integration over the radiation pattern. Finally, the antenna gain is obtained from the measurement of a two-antenna system.

碩士
國立臺灣海洋大學
機械與機電工程學系
100
We presented a multi-polarization spectral integration method to increase the refractive index detection limit of gold nanostructures. This analysis method considers all resonances in transmission spectra for various polarized light. By integrating all the intensity changes over all the polarized resonances, the noise level is greatly decreased. For a nanoslit structure the signal-to-noise ratio is increased about 1.7 times larger than the simple spectral integration method. Further studies with dual-period nanogrid structures show that the signal-to-noise ratio and refractive index detection limit are increased to 8.16 times due to more resonances in different polarization states. The nanogrid structures achieve a detection limit of 2.26×10-6 refractive index unit when the intensity stability is 0.2%. The proposed method provides an efficient way for improving surface plasmon detection limits of polarization-dependent metallic nanostructures.

Two surface wave testing methods, namely, (i) the spectral analysis of surface waves (SASW), and (ii) the multi-channel analysis of surface waves (MASW), form non-destructive and non-intrusive techniques for predicting the shear wave velocity profile of different layers of ground and pavement. These field testing tools are based on the dispersive characteristics of Rayleigh waves, that is, different frequency components of the surface wave travel at different velocities in layered media. The SASW and MASW testing procedure basically comprises of three different components: (i) field measurements by employing geophones/accelerometers, (ii) generating dispersion plots, and (iii) predicting the shear wave velocity profile based on an inversion analysis. For generating the field dispersion plot, the complexities involved while doing the phase unwrapping calculations for the SASW technique, while performing the spectral calculations on the basis of two receivers’ data, makes it difficult to automate since it requires frequent manual judgment. In the present thesis, a new method, based on the sliding Fourier transform, has been introduced. The proposed method has been noted to be quite accurate, computationally economical and it generally overcomes the difficulties associated with the unwrapping of the phase difference between the two sensors’ data. In this approach, the unwrapping of the phase can be carried out without any manual intervention. As a result, an automation of the entire computational process to generate the dispersion plot becomes feasible. The method has been thoroughly validated by including a number of examples on the basis of surface wave field tests as well as synthetic test data. While obtaining the dispersion image by using the MASW method, three different transformation techniques, namely, (i) the Park’s wavefield transform, (ii) the frequency (f) -wavenumber ( ) transform and (iii) the time intercept ( -phase slowness (p) transform have been utilized for generating the multimodal dispersion plots. The performance of these three different methods has been assessed by using synthetic as well as field data records obtained from a ground site by means of 48 geophones. Two-dimensional as well as three-dimensional dispersion plots were generated. The Park’s wavefield transformation method has been found to be especially advantageous since it neither requires a very high sampling rate nor an inclusion of the zero padding of the data in a wavenumber (distance) domain. In the case of an irregular dispersive media, a proper analysis of the higher modes existing in the dispersion plots becomes essential for predicting the shear wave velocity profile of ground on the basis of surface wave tests. In such cases, the establishment of the predominant mode becomes quite significant. In the current investigation for Rayleigh wave propagation, the predominant mode has been computed by maximizing the normalized vertical displacements along the free surface. Eigenvectors computed from the thin layer approach (TLM) approach are analyzed to predict the corresponding predominant mode. It is noted that the establishment of the predominant mode becomes quite important where only two to six sensors are employed and the governing (predominant) modal dispersion curve is usually observed rather than several multiple modes which can otherwise be identified by using around 24 to 48 multiple sensors. By using the TLM, it is, however, not possible to account for the exact contribution of the elastic half space in the dynamic stiffness matrix (DSM) approach. A method is suggested to incorporate the exact contribution of the elastic half space in the TLM. The numerical formulation is finally framed as a quadratic eigenvalue problem which can be easily solved by using the subroutine polyeig in MATLAB. The dispersion plots were generated for several chosen different ground profiles. The numerical results were found to match quite well with the data available from literature. In order to address all the three different aspects of SASW and MASW techniques, a series of field tests were performed on five different ground sites. The ground vibrations were induced by means of (i) a 65 kg mass dropped freely from a height of 5 m, and (ii) by using a 20 pound sledge hammer. It was found that by using a 65 kg mass dropped from a height of 5 m, for stiffer sites, ground exploration becomes feasible even up to a depth of 50-80 m whereas for the softer sites the exploration depth is reduced to about 30 m. By using a 20 lb sledge hammer, the exploration depth is restricted to only 8-10 m due to its low impact energy. Overall, it is expected that the work reported in the thesis will furnish useful guidelines for (i) performing the SASW and MASW field tests, (ii) generating dispersion plots/images, and (iii) predicting the shear wave velocity profile of the site based on an inversion analysis.

博士
中興大學
應用數學系所
98
In this dissertation we study three methods such as a novel multigrid-continuation method, multi-level spectral-Galerkin continuation method and pseudo-spectral continuation method where the Fourier sine functions are used as the basis functions for treating parameter-dependent problems. The proposed algorithms are exploited to compute energy levels and superfluid densities of Bose-Einstein condensation (BEC) in a periodic potential, which is governed by the nonlinear Schr¨odinger equation (NLS). Both positive and negative scattering lengths are onsidered in our numerical experiments. For positive scattering length, if the chemical potential is large enough, and the domain is properly chosen, the results show that the number of peaks of the first few energy states of the 2D BEC in a periodic potential depends on the wave number of the periodic potential. First, we present a novel multigrid-continuation method for treating parameterdependent problems. The proposed algorithm which can be flexibly implemented is a generalization of the two-grid discretization schemes [1]. That is, approximating points on a solution curve do not necessarily lie on the same fine grid. Our numerical results show that for bright solitons the number of peaks of the ground state solutions is (1/d−1)^2 and (1/d)^2, where the periodic potential is expressed in terms of the sine or the cosine functions, respectively. However, these formulae do not hold if the scattering length is negative. The numerical study is extended to the twocomponent, 1D and 2D BEC in a periodic potential. Next, we study multi-level spectral-Galerkin continuation methods for parameterdependent problems, where the Fourier sine functions are used as the basis functions. The algorithm which has the advantage over the single level method is that certain amounts of computational cost can be saved. Our numerical results show that if the chemical potential is large enough and the domain Ω = (0, 1)^n, n = 1, 2, the number of peaks of the ground state solution of the BEC in a periodic potential is Π^n_{j=1}(1/dj − 1), where dj is/are the distance of neighbor wells in the x-coordinate (respectively, x- and y-coordinate). For a large domain Ω = (−l, l)^n, l > 1, we obtain the more general formula Π^n_{j=1}( 2l/dj − 1) for the ground state solution of the BEC. Finally, we study pseudo-spectral continuation method for treating parameterdependent problems, where the Fourier sine functions are used as the basis functions. This algorithm was advocated as a fast and efficient method for computing the energy levels of the Gross-Pitaevskii quation (GPE) in a periodic potential. The numerical results of 1D and 2D GPE in a periodic potential are reported.

碩士
國立成功大學
電機工程學系碩士在職專班
103
This thesis aims at the multi-spectral image error caused during the transmission of the remote sensing satellite image to combine the panchromatic image with multi-spectral B1, B2, B3 images as a way to generate predicted B ̃_4 image for restoration. In case the multi-spectral B1, B2, B3 images are used respectively to patch the B4 image, though the structure of the band image is similar, the difference of the reflective spectrum on four typical land objects (snow, desert, wetland, vegetation) is significant that the image looked unnatural so the existing algorithm is applied to improve the current loss. The panchromatic band covers most of the multi-spectral bands that the multi-spectral image data is included in the PAN image, and through the fusion of the non-damaged multi-spectral images and the data of these images to generate the B ̃_4 image prediction as a reference image to restore the multi-spectral image B4. The experimental results indicated that the algorithm may stably strengthen up the existing algorithm to better the image quality and allow the overall image look much natural, also, to present more details contained in the multi-spectral band image B4 clearly.