Approved for public release; distribution is unlimited / Variability of the MABL and its effect on the electromagnetic (EM) refractive structure around the Greenland Sea marginal ice zone were examined. Rawinsonde profiles and surface observations collected from 3 ships during MIZEX-87(20 March-11 April) served as the data set. A program, developed to calculate the refractivity at each vertical level of the rawinsonde profiles, also identified the levels at which trapping, superrefraction and subrefraction occurred. Temporal studies showed that a higher incidence of anomalous refractive layers occurred during periods when the region was under the influence of high pressure. More than 50% of the time, trapping and super-refractive layers were attributed to development of a capping inversion just above the MABL during these periods. Spatial studies showed that the refractive structure varied relative to distance from the ice edge as did the depth of the MABL. An upward slope in refractive layer heights was observed from the ice toward the open water. Significant spatial inhomogeneity was observed over horizontal ranges of less than 100 km. This was attributed to both the large-scale synoptic forcing affecting the region and to variations in the surface fluxes of heat and moisture over the ice and over the water. A range-dependent ray trace model developed at the Naval Ocean Systems Center was used to show how the ray paths of EM waves vary with a changing refractive structures. Keywords: Air water interactions, Greenland Sea, Atmospheric refraction, Electromagnetic wave propagation, Heat flux, Sea ice. Theses. (EDC) / http://archive.org/details/temporalspatialv00grot / Lieutenant, United States Navy

Neste trabalho, apresentamos uma extensão da técnica de varredura-Z baseada na análise espectral da evolução temporal da transmitância, quando um feixe laser é modulado numa freqüência f. As componentes de Fourier da evolução temporal da transmitância em f e 2f estão respectivamente relacionadas com os efeitos lineares e não-lineares e sua razão pode ser usada na eliminação de efeitos lineares. Este método, denominado varredura-Z resolvida em frequência, permite um aumento significativo na sensibilidade da técnica de varredura-Z em medidas de absorvedores lentos. Tal método se combinado com \"EZ-scan\" permite medidas de modulação de fase correspondentes a distorções da frente de onda de λ/105. A aplicabilidade bem como a sensibilidade desta técnica foram demonstradas em medidas realizadas em absorvedores lentos, especificamente o rubi e o aluminato de gadolínio dopado com cromo. Tais materiais são convenientes para estes fins, pois já tiveram suas não-linearidades investigadas anteriormente por diversos métodos. Como aplicação da técnica fizemos medidas das propriedades ópticas lineares e não-lineares em uma amostra de vidro fluoroindato dopado com cromo. Observamos que os valores de n2 (λ) seguem a curva de absorção desse material, e propomos um modelo que relaciona a origem da não-linearidade com as transições eletrônicas que ocorrem na região do visível. / This work presents an extension of the Z-scan technique based on the spectral analysis of the transmittance time-evolution when the laser beam is modulated at a frequency f. The Fourier components of the transmittance time-evolution at f and 2f are respectively related to the linear and nonlinear effects and their ratio can be used to eliminate spurious linear effects. This method, known as frequency resolved Z-scan, allows a significative increase in the sensitivity of the Z-scan technique for measurements of slow absorbers. When combined with the EZ-scan technique, it can measure transmittance changes corresponding to wavefront distortions of λ/105. The demonstration of the technique was carried out for slow absorbers, ruby and chromium-doped gadolinium aluminate. Such materials were conveniently chosen for this purpose since their optical nonlinearities are well stablished. As an application, we present linear and nonlinear optical properties of a chromium-doped fluorindate glass sample. We found that the values of n2 (λ) follow the absorption curve in this material and we have proposed a model which relates the origin of the nonlinearity with the electronic transitions that occur in the visible region of the spectrum.

A pesquisa teve como objetivo integrar o método GPR (Ground Penetrating Radar) com a sísmica de refração, visando o mapeamento do N.A. e a estimativa do teor de umidade em uma área de estudos hidrogeológicos no campus da USP, assim como analisar a acurácia da medida dos dois métodos. Foram realizados ensaios geofísicos, granulométricos, de teor de umidade, do grau de saturação, do monitoramento do N.A. e acompanhamento dos índices pluviométricos em três períodos com variações sazonais no decorrer de um ano denominados período chuvoso (janeiro/2004); período intermediário (abril/2004) e período seco (setembro/2004). O mapeamento do N.A. com GPR foi feito com geometria multi-offset, com as antenas de freqüências centrais 50 MHz, 100 MHz e 200 MHz, sendo que as antenas de 100 MHz e 200 MHz foram as que caracterizaram o N.A., refletindo sua variação sazonal e mantendo a tendência prof. N.A. janeiro < prof. N.A. abril < prof. N.A. setembro. O emprego da sísmica de refração gerou maiores erros e ambigüidades na inversão dos dados. Neste estudo, a sísmica de refração não foi sensível às variações sazonais e, embora os resultados tenham se aproximado das observações diretas, não permitiram mapear a flutuação do N.A. entre os diferentes períodos. A estimativa do teor de umidade volumétrico pelo GPR foi obtida com duas metodologias diferentes que utilizaram a onda direta no solo. Foram empregadas antenas de 50 MHz, 100 MHz e 200 MHz nos diferentes períodos. Observou-se uma variação da umidade entre os períodos, sendo o teor de umidade de janeiro > abril > setembro. A antena de 200 MHz foi a que possibilitara uma melhor acurácia na estimativa do teor de umidade volumétrico. / The present study had as objective to integrate GPR (Ground Penetrating Radar) method to seismic refraction, focusing on water table mapping and on the estimate of water content in an area of hydrogeological studies at USP\'s campus, as well as analysing the measuring accuracy of both methods. Several assays were accomplished, such as geophysical, granulometric, of water content, saturation degree, water table monitoring assays and also accompaniment of pluviometric indexes in the study periods with seasonal variations, along a year, denominated rainy period (january/2004), intermediaty period (april/2004), and dry period (september/2004). Water table mapping by GPR was made with multi-offset geometry, with 50 MHz, 100 MHz and 200 MHz central frequency antennas, seeing that 100 MHz and 200 MHz antennas were those ones, which characterized the water table, reflecting its seasonal variation and maintaining the depth of the water tablejanuary < depthapril < depthseptember tendency. The use of seismic refraction generated larger mistakes and ambiguities in the data inversion. In this study, seismic refraction was not sensitive to seasonal variations and, although the results have approached to direct observations, they did not allow mapping the water table fluctuation among the different periods. The estimate of volumetric water content by GPR was obtained with two different methodologies that have used the direct ground wave. Fifty MHz, 100 MHz and 200 MHz antennas were used in the different periods. A moisture variation was observed among these periods, being the water content of January > April > September. Two hundred MHz antenna was the one that had facilitated a better accuracy in the estimate of moisture content.

Desembocaduras são ambientes bastante dinâmicos e sujeitos à complexa interação entre fatores estabilizadores e desestabilizadores. Dependendo dessa interação, desembocaduras podem apresentar a tendência de migração ao longo de barreiras arenosas. Um dos mecanismos mais eficientes de transporte de sedimento paralelo à costa, e conseqüentemente migração de canais, são as correntes longitudinais geradas pelas ondas se aproximando obliquamente a costa. A motivação do presente trabalho é entender o comportamento morfodinâmico do sistema de desembocadura do rio Itapocú, localizado no centro-norte de Santa Catarina, frente aos processos forçantes que atuam na sua migração ao longo da linha de costa. A morfologia dos pontais arenosos foi obtida a partir de levantamentos morfológicos com o uso de DGPS. Para analisar a refração de ondas foi utilizado o modelo numérico MIKE 21 - SW, sendo considerados como condições de contorno dados de ondas referentes ao ano de 2002 e dados de ondas previstos referentes ao período de coleta. Os dados de saída do modelo foram utilizados para estimar a deriva litorânea potencial na região. Os resultados morfológicos obtidos demonstraram uma migração da desembocadura para o norte durante o período analisado, sendo mais intenso durante o inverno e o verão. A refração de ondas incidentes do quadrante sul sofreram mais o fenômeno da refração e as ondas de leste apresentaram menor variação angular ao se aproximarem da costa. A deriva litorânea potencial anual para os dados de ondas de 2002 apresentou sentido norte-sul, com inversão de sentido durante o outono, sul-norte. A deriva litorânea potencial para os dados referentes ao período estudado apresentou sentido sul-norte, concordando com a migração observada. A deriva potencial em frente aos pontais apresentou direção para o norte durante todas as estações. Os dados de descarga fluvial não apresentaram influência na migração do canal, porém apresentaram uma relação com a largura do mesmo sazonalmente. Os dados de morfologia juntamente com os dados de deriva litorânea referentes às ondas de 2004/2005 mostraram claramente a migração do canal para o norte sendo a deriva a principal contribuinte para a migração da desembocadura. / Inlets are highly dynamic environments subjected to the complex interaction between stabilizing and destabilizing factors. Depending on this interaction, inlets have a tendency to migrate along sandy barriers. One of the most effective mechanisms for transporting sediment alongshore and consequently controlling the migration of inlets, are currents generated by waves approaching the coast at an angle. The motivation of this study is to better understand the morphodynamic behavior of the Itapocú inlet, at the northern Santa Catarina coast. The morphology of the sandy spits that enclose the inlet was obtained from morphological surveys conducted with the use of DGPS. To analyze the wave refraction the numerical model MIKE 21 SW has been applied to the region. Boundary conditions have been set based on a one-year long database (2002) and predicted waves for the studied period. The model output has been used to estimate the potential longshore drift in the region. Results show the migration of the inlet to the north during the analyzed period, with higher migration rates during winter and summer. Waves inciding from the south are the most influenced by the refraction process, while the less refracted waves are those coming from the east The net longshore drift obtained when using the 2002 database is southwards, presenting slight inversions during the year. When using the predicted wave data for the studied period, the potential longshore drift is dominated by northward direction, in agreement with the observed inlet migration. The Itapocú river discharge does not present any relation with the observed inlet migration rates, although there seems to be a relation with the seasonal channel width variability. The surveyed morphological evolution is well related to the potential longshore drift, indicating that during the monitored period, the northwards inlet migration is being controlled by the wave generated longshore drift.

Desembocaduras são ambientes bastante dinâmicos e sujeitos à complexa interação entre fatores estabilizadores e desestabilizadores. Dependendo dessa interação, desembocaduras podem apresentar a tendência de migração ao longo de barreiras arenosas. Um dos mecanismos mais eficientes de transporte de sedimento paralelo à costa, e conseqüentemente migração de canais, são as correntes longitudinais geradas pelas ondas se aproximando obliquamente a costa. A motivação do presente trabalho é entender o comportamento morfodinâmico do sistema de desembocadura do rio Itapocú, localizado no centro-norte de Santa Catarina, frente aos processos forçantes que atuam na sua migração ao longo da linha de costa. A morfologia dos pontais arenosos foi obtida a partir de levantamentos morfológicos com o uso de DGPS. Para analisar a refração de ondas foi utilizado o modelo numérico MIKE 21 - SW, sendo considerados como condições de contorno dados de ondas referentes ao ano de 2002 e dados de ondas previstos referentes ao período de coleta. Os dados de saída do modelo foram utilizados para estimar a deriva litorânea potencial na região. Os resultados morfológicos obtidos demonstraram uma migração da desembocadura para o norte durante o período analisado, sendo mais intenso durante o inverno e o verão. A refração de ondas incidentes do quadrante sul sofreram mais o fenômeno da refração e as ondas de leste apresentaram menor variação angular ao se aproximarem da costa. A deriva litorânea potencial anual para os dados de ondas de 2002 apresentou sentido norte-sul, com inversão de sentido durante o outono, sul-norte. A deriva litorânea potencial para os dados referentes ao período estudado apresentou sentido sul-norte, concordando com a migração observada. A deriva potencial em frente aos pontais apresentou direção para o norte durante todas as estações. Os dados de descarga fluvial não apresentaram influência na migração do canal, porém apresentaram uma relação com a largura do mesmo sazonalmente. Os dados de morfologia juntamente com os dados de deriva litorânea referentes às ondas de 2004/2005 mostraram claramente a migração do canal para o norte sendo a deriva a principal contribuinte para a migração da desembocadura. / Inlets are highly dynamic environments subjected to the complex interaction between stabilizing and destabilizing factors. Depending on this interaction, inlets have a tendency to migrate along sandy barriers. One of the most effective mechanisms for transporting sediment alongshore and consequently controlling the migration of inlets, are currents generated by waves approaching the coast at an angle. The motivation of this study is to better understand the morphodynamic behavior of the Itapocú inlet, at the northern Santa Catarina coast. The morphology of the sandy spits that enclose the inlet was obtained from morphological surveys conducted with the use of DGPS. To analyze the wave refraction the numerical model MIKE 21 SW has been applied to the region. Boundary conditions have been set based on a one-year long database (2002) and predicted waves for the studied period. The model output has been used to estimate the potential longshore drift in the region. Results show the migration of the inlet to the north during the analyzed period, with higher migration rates during winter and summer. Waves inciding from the south are the most influenced by the refraction process, while the less refracted waves are those coming from the east The net longshore drift obtained when using the 2002 database is southwards, presenting slight inversions during the year. When using the predicted wave data for the studied period, the potential longshore drift is dominated by northward direction, in agreement with the observed inlet migration. The Itapocú river discharge does not present any relation with the observed inlet migration rates, although there seems to be a relation with the seasonal channel width variability. The surveyed morphological evolution is well related to the potential longshore drift, indicating that during the monitored period, the northwards inlet migration is being controlled by the wave generated longshore drift.

Orientador : Paulo de Oliveira Camargo / Resumo: Atualmente, a maior fonte de erro sistemático no posicionamento com receptores GPS de uma freqüência é devido à refração ionosférica. O erro associado à refração ionosférica depende do conteúdo total de elétrons (TEC) na camada ionosférica, que por sua vez, é influenciado por diversas variáveis, tais como: ciclo solar, época do ano, hora do dia, localização geográfica e atividade geomagnética, e é difícil de ser corrigido. Os receptores GPS de dupla freqüência permitem efetuar correções do efeito da refração ionosférica, devido ao fato da mesma ser dependente da freqüência do sinal. Porém, receptores GPS de dupla freqüência são equipamentos caros, fazendo com que os de uma freqüência sejam amplamente empregados no posicionamento com GPS. As mensagens de navegação trazem informações que permitem efetuar correções da ionosfera para receptores GPS de uma freqüência, utilizando o modelo de Klobuchar. Porém vários estudos realizados mostraram que o modelo de Klobuchar pode remover apenas algo em torno de 50-60% do efeito total. Desta maneira, é necessário dispor de uma estratégia mais efetiva de eliminar os efeitos da ionosfera, a qual tem sido investigada a partir do uso de modelos regionais para a ionosfera. No Brasil, tem-se o modelo regional da ionosfera (Mod_Ion), desenvolvido na FCT/UNESP, que utiliza dados GPS da Rede Brasileira de Monitoramento Contínuo (RBMC). Neste modelo, a ionosfera é representada analiticamente pela série de Fourier. Nesta pesquisa, outras funções de modelagem e de mapeamento da ionosfera foram implementadas no Mod_Ion, visando melhorar a eficiência do modelo para posicionamento com receptores de uma freqüência. Os resultados dos experimentos do posicionamento por ponto mostraram que as funções série de Fourier, de Taylor e a polinomial foram as mais eficazes na correção do efeito sistemático...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nowadays, one of the main drawbacks of the GPS accuracy for L1 users is the ionospheric refraction, which affects, mainly, the point positioning. The error associated with the ionospheric refraction depends on the Total Electron Content (TEC) in the ionospheric layer, that is influenced by several variables, including the solar cycle, the season, the local time, the geographical location of the receiver and the Earth's magnetic field. The broadcast ephemeris contains information for computing the group delay, using the broadcast model. The literatures report that the model correct 50 to 60% of the total effect of ionospheric refraction. Therefore, it is necessary a more effective strategy of eliminating the effects of the ionosphere. Some techniques and models have been developed to estimate these effects using data collected with double frequency GPS receivers. In Brazil, a regional model of the ionosphere (Mod_Ion) was developed in FCT/UNESP, which makes use of GPS data collected at the active stations of RBMC (Brazilian Network for Continuous Monitoring of GPS satellites) In this model, the ionosphere is represented analytically by a Fourier series type. In this research, other modelling and mapping functions of the ionosphere were implemented in Mod_Ion, seeking to improve the efficiency of the model for positioning with L1 receivers. The results of the experiments showed that the functions: Fourier series, Taylor series and the polynomial, were the most effective in the correction of the systematic effect due to the ionosphere, providing a improvement in the acuracy better than 79,5%, with values of discrepancies in the resultant of the cartesian coordinates better than 3 m, and the largest influence concentrates on the height. / Mestre

The San Andreas Fault stretches for over 800 miles through California. Along the foothills of the San Bernardino Mountains, areas in close proximity to the San Andreas Fault Zone may be subject to site amplification of ground motion caused by seismic activity via wave propagation through the subsurface. These seismic hazards are being addressed via the Alquist-Priolo Earthquake Faulting Zone Act and the National Earthquake Hazards Reduction Program (NEHRP). Shear wave velocity of the subsurface has served as a proxy for ground motion amplification and is therefore a useful parameter to help analyze and reduce seismic hazards. Low shear wave velocities of the subsurface have been known to correlate with higher amplitude ground motion. This study focuses on refraction microtremor analysis (ReMi) of the subsurface in Northern San Bernardino; more specifically, areas encompassing California State University San Bernardino, in close proximity to the San Andreas Fault. The technique will resolve shear wave velocity values for the top 30 meters (Vs30) of the subsurface. This depth of investigation has proven to be an effective means in determining subsurface conditions. ReMi profiles were situated 0.25 to 2.0 miles away from the San Andreas Fault, and in some instances, strategically positioned next to housing developments and structures. Phase velocity dispersion curves were generated by processing ReMi seismic data and subsequently inverted to attain average shear wave velocity profiles with depth. The geologic units in the study area consist of very young wash deposits, young alluvial fan deposits and Pelonist schist deposits. These geologic units may be an indicator to how seismic waves behave in subsurface lithology. To highlight differences in Vs30 values across the project area, a microzonation map was constructed.

This thesis deals with the topic of reflection and refraction of light from the boundary of nonlinear materials in general, and saturating amplifiers in particular. We first study some of the basic properties of the light waves in nonlinear materials. We then develop a general formalism to model the reflection and refraction of light with an arbitrary angle of incidence from the boundary of a nonlinear medium. This general formalism is then applied to the case of reflection and refraction from the boundary of linear dielectrics. It will be shown that in this limit, it reduces to the well known Fresnel and Snell's formulas. We also study the interface of a saturating amplifier. The wave equation we use for this purpose is approximate, in the sense that it assumes the amplitude of the wave does not vary significantly in a distance of a wave length. The limits and implications of this approximation are also investigated. We derive expressions for electric field and intensity reflection and transmission coefficients for such materials. In doing so, we make sure that the above mentioned approximation is not violated. These results are compared with the case of reflection and refraction from the interface of a linear dielectric.

Metamaterials are artificial structures, which periodically arranged to exhibit fascinating electromagnetic properties, not existing in nature. A great deal of research in the field of metamaterial was conducted in a linear regime, where the electromagnetic responses are independent of the external electric or magnetic fields. Unfortunately, in linear regime the desired properties of metamaterials have only been achieved within a narrow bandwidth, around a fixed frequency. Therefore, nonlinearity is introduced into metamaterials by merging meta-atoms with well-known nonlinear materials. Nonlinear metamaterials are exploited in this dissertation to introduce and develop applications in microwave frequency with broadband responses. The nonlinearity was achieved via embedding varactor diode on to split ring resonator (SRR) design, which demonstrates tunability in resonance frequency and phase of the transmission signal. SRR exhibits power and frequency dependent broadband tunability and it is realized for external electro-magnetic signals. More importantly, the nonlinear SRR shows bi-stability with distinct transmission levels, where the transition between bi-states is controlled by the impulses of pump signal and it can be used as a switching device in microwave regime. In order to increase its functionality in other frequencies, a new design, double split ring resonator (DSRR) is introduced with two rings, which has two distinct resonance frequencies. The double split ring resonator also demonstrate similar behavior as the SRR but it is broadband. Furthermore, by designing the structure such that the inner ring has a frequency twice as outer ring resonance frequency; we observed the enhancement of harmonic generation. We exhibit enhancement in second harmonic generation and methods that can use to increase the harmonic signal power. Arranging the unit cells in an array and particular orientation further increases the harmonic power. In addition, we show that using a back plate to create a cavity will help to increase harmonic power. Furthermore, we have demonstrated that applying an external DC voltage can be used to tune resonance frequency as well as phase of the signal. Exploring these ideas in THz frequency regime is also important. So simulation results were obtained with advanced designs to achieve non-linearity in terahertz frequency regime to realize tunability, hysteresis and bi-stable states. A negative refractive index can be realized in metamaterials consisting of strong magnetic and electric resonators with responses at the same frequency band. However, high loss and narrow bandwidth resulting from strong resonances have impeded negative index optical components and devices from reaching expected functionalities (e.g. perfect lens). Here, we demonstrate experimentally and numerically that a 2D helical chiral metamaterial exhibits broadband negative refractive index with extremely low loss. With Drude-like dispersion, its permittivity leads to zero-index, and broadband chirality further brings the index to negative values for left-handed circularly polarized light in the entire range below the plasma frequency. Non-resonant architecture results in very low loss (<2% per layer) and an extremely high Figure-of-merit (>90). Tunable THz metamaterials has shown great potential to solve the material challenge due to the so-called “THz gap”. However, the tunable mechanism of current designs relies on using semiconductors insertions, which inevitably results in high Ohmic loss, and thereby significantly degrades the performance of metamaterials. In this work, we demonstrate a novel tunable mechanism based on polymeric microactuators. Our metamaterials are fabricated on the surface of patterned pillar array of flexible polymers embedded with magnetic nanoparticles. The transmission spectrum of the metamaterial can be tuned as the pillars are mechanically deformed though applied magnetic field. We observed and measured several type of deformation including bending, twisting and compressing when the applied magnetic field is polarized along different direction with respected to the axis of the magnetic particles. Compared to previous semiconductor based tunable mechanism, our structure has shown much lower loss. We demonstrate using simulations and experimentally that with an external magnetic field, we can achieve phase modulation using magnetic polymeric micro-actuators.

Birefringence measurements are of great importance in a plethora of applications spanning from biology to optical communications. Birefringence measurements of nerve-fiber layers have emerged as an important diagnostic technique for early detection of glaucoma. Stress-induced birefringence in optical devices affects their performances by causing Polarization-Mode Dispersion (PMD) and Polarization-Dependent Loss (PDL). Stress-relaxation constitutes a key phenomenon governing the fabrication of some optical devices such as Long-Period Fiber Gratings (LPFGs). This drives the need to develop accurate optical instrumentation techniques to evaluate form and stress-induced birefringence. This thesis deals with the development of new high-accuracy techniques for the characterization of stress-induced birefringence in optical devices. The new Two-Waveplate Compensator (TWC) technique is presented for single-point retardation measurements. It is extensively compared theoretically and experimentally to existing techniques including the Snarmont and Brace-Khler techniques. The Phase-Stepping Two-Waveplate Retarder (PSTWR) is also presented for high-accuracy measurements of retardation magnitude and orientation. The Colorimetry-Based Retardation Method (CBRM) is presented to measure retardation using white-light interference colors. The technique is implemented using a polarization microscope and a spectrophotometer. The TWC and the Brace-Khler methods are implemented for full-field retardation measurements using a polarization microscope. Their accuracies are quantified over the entire field-of-view for small retardations. They are applied to the stress-induced birefringence imaging of LPFGs and polymer pillar waveguides. The TWC technique achieves an accuracy of 0.06 nm and a sensitivity of 0.07 nm. The Brace- Khler technique achieves an accuracy of 0.04 nm and a sensitivity of 0.09 nm. The spatial resolution of both techniques is 0.45 and #61549;m. A Fourier-based algorithm is presented to compute the inverse Abel transform relating the retardation to the axial residual stress profile in optical fibers. It is used to calculate the residual stress profiles of single-mode fibers from full-field retardation measurements with the TWC and Brace- Khler techniques. The stress profiles computed in this work are in very good agreement with previously reported results in the literature. The TWC technique produces the most accurate stress measurements. The TWC technique is used to investigate the stress-relaxation phenomena in LPFGs fabricated using CO2 laser irradiations.