Digital heterodyne methods are employed in conjunction with periodic fringe projection to produce a fast automated surface relief measurement technique. A method of sampling the image with a solid state detector array which produces a moire fringe image free of the noise terms normally present with moire techniques is presented along with an extension to Whittaker-Shannon sampling theory to cover the moire aliasing phenomena. The limitations imposed on the surface slopes by the requirement that the properly moire sampled image spectra must be confined to a moire interval are given. Moire sampling allows an optical processing step (removal of the reference surface tilt), while classical nonaliased sampling produces the same information with respect to a tilted surface. General additive noise is analyzed as regards both integrating bucket and phase stepping algorithms and yields a signal to noise ratio dependent error with twice the frequency of the fringes for some algorithms. A phase averaging technique which eliminates these oscillatory errors as well as those caused by reference phase shift errors in all the algorithms is demonstrated. Both parallel and divergent geometries are discussed. The feasibility is experimentally demonstrated with results for the parallel case based on a system composed of commercially obtainable components.

A three-beam lateral shearing interferometer has been developed. The three-beam shearing interferograms consist of two sets of fringes, one of which acts as a carrier whose intensity is modulated by the second set. The depth of modulation is directly proportional to the phase difference between the middle beam and the outer beams. Phase errors on the order of π/2 cause every other fringe to go from complete dark to complete bright. Therefore, phase errors much smaller than π/2 can be detected. The three-beam interferometer is implemented in three ways: (1) thin film thickness measurement, (2) surface roughness measurement, and (3) surface figure measurement. The three-beam interferometer implemented to measure thin film thickness and surface roughness is accurate to 25 Å. Surfaces with different microstructure are characterized. We have found that each of those surfaces may have one or more of the following: (1) random roughness, (2) slow waviness, and/or (3) periodic structure. The three-beam interferometer is also implemented for testing optical surfaces. The three-beam interferometer is more capable in detecting small zonal errors than the two-beam interferometer. Three-beam interferograms of different surfaces are produced and analyzed. The three-beam interferometer has many advantages: (1) it is a stable, common path interferometer, (2) white light can be instead of coherent light to get rid of the effects of speckle and dust particles, and (3) it is a very low cost interferometer.

Shortened periods of inundation due to water management have led to the encroachment and expansion of Carolina willow (Salix caroliniana) in sawgrass (Cladium jamaicense) marsh communities. Morphologic and physiologic differences between sawgrass and willow have potential consequences for microhabitat conditions and ecosystem function such as a reduction in temperatures and light availability and changes in primary productivity. Since it is a woody shrub, willow is often assumed to exhibit higher rates of transpiration than non woody plants, which in turn can affect photosynthesis and carbon exchange and ultimately wetland water management. In this study willow was found to have higher rates of stomatal conductance (gs) and photosynthesis (Anet) than sawgrass. However, sawgrass had greater intrinsic water use efficiency (WUE) than willow. This suggests that willow is capable of greater gas exchange and carbon assimilation than sawgrass but requires more water. Understanding the implications of willow expansion will improve landscape models of wetland water and carbon exchange and inform water management decisions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

This dissertation will demonstrate the synergy of nanoscopic materials and surface metrology methods by the fabrication and implementation of CNT atomic force microscopy (AFM) tips, CNT scanning tunneling microscopy (STM) tips, Pt spike AFM tips, and Pt spike near-field scanning optical microscopy (NSOM) tips for the methods of critical dimension metrology, STM, AFM phase imaging, scanning surface potential AFM (SSPM), NSOM, and three-dimensional AFM. Chapter 1 provides a general overview of the information that will be discussed in this dissertation. Chapter 2 describes two methods for the simultaneous fabrication of carbon nanotube atomic force microscopy and scanning tunneling microscopy probes. The fabrication of these high resolution probes, as well as their imaging characteristics, is described in detail. Resolution standards were used to characterize their behavior and resolution limits. In Chapter 3, the effect of high aspect ratio probe length on AFM phase imaging is studied by fabricating highly controllable Pt spike AFM tips. By monitoring phase shifts on homogenous surfaces as a function of Pt spike length, it is shown that attractive forces at the tip are significantly reduced when high aspect ratio structures are added to conventional AFM probes. In Chapter 4, the effect of probe geometry on scanning surface potential microscopy (SSPM) is described. By studying the effect of scan height in SSPM, it was found that large surface area probe geometries, such as conventional Pt coated AFM tips, have lower surface potential resolution because of contributions from the sides of the tip as well as the cantilever. Spatial resolution standards were probed to evaluate the effect of probe geometry on SSPM sensitivity and resolution. Chapter 5 describes the fabrication of specialized probes for three-dimensional atomic force microscopy, scanning near-field optical microscopy, and scanning electrochemical -- atomic force microscopy (SECM-AFM). Using techniques described in Chapters 2-4, high aspect ratio structures were added to conventional probes used in 3D AFM, NSOM and SECM-AFM to solve limitations inherent to current probe designs for each method. Preliminary data indicates that each probe will have a significant beneficial effect on the resolution limit of its technique.

The relative rates of detrital decomposition in four vegetation communities within the Everglades' ridge-slough microtopography were evaluated during two trials. Litterbags with community-specific detritus in proportion to each community's composition were put into the four communities; namely, submerged marsh, emergent marsh, short Cladium ridge, and tall Cladium ridge. These litterbags were paired with litterbags containing control leaf litter from Chrysobalanus icaco and Salix caroliniana during the wet and dry season trials, respectively. No regional differences in decomposition were shown, but there were significant differences across communities, attributed to the initial C:N ratio of the detritus, with the fastest decomposition occurring in the deepest submerged marsh followed by emergent marsh, and the shallower ridge communities had equally slower decomposition. Additionally, both controls followed the same pattern. Thus, decomposition contributes to an active self-maintenance mechanism within the vegetation communities which ultimately helps to conserve the ridges and sloughs. / by Sheryl R. van der Heiden. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

O movimento relativo entre superfícies planas de contato são comuns a muitos projetos de engenharia. Na operação de muitos mecanismos identificam-se os problemas de atrito como um dos principais obstáculos para o êxito do funcionamento desses dispositivos. Neste trabalho avaliou-se a influência da pressão nominal de contato no atrito estático entre superfícies de aço ABNT 1020 e 1045 contra uma placa de vidro. As superfícies dos corpos de prova foram obtidas através do Processo de Fabricação por Usinagem Com Ferramenta de Geometria Não Definida – Retificação Plana Tangencial. Os corpos de prova foram constituídos de dois grupos: o Grupo A (tipo copo - ABNT1010) e do Grupo B (tipo Maciço - ABNT1045). Todas as superfícies foram caracterizadas quanto à rugosidade, utilizando-se um perfilômetro 3-D óptico sem contato. Para as medições do atrito estático foi utilizado um sistema plano inclinado, com automatização para detecção dos movimentos dos corpos de prova ao longo do tempo. Demonstrou-se que a pressão nominal não influencia os valores de coeficiente de atrito estático. Investigou-se a partir de então, um possível efeito da rugosidade no atrito. A partir dos parâmetros de rugosidade 3D foram calculados os momentos espectrais m0, m2 e m4, e o Parâmetro Largura de Banda, Alfa (α) que foi correlacionado com o coeficiente de atrito estático. Dentro dos parâmetros analisados: Sq, Sdq e Sds, o parâmetro Sq foi o que apresentou a maior discrepância entre os dados coletados. Com base na análise estatística de variância com nível de confiança de 5%, do parâmetro Sq, as amostras foram realocadas em 4 grupos para os quais foram calculados os Parâmetros Alfa. Considerando-se estes grupos de amostras, mostrou-se que o parâmetro alfa afetou o coeficiente de atrito estático, ou seja, quanto maior o parâmetro, maior o coeficiente de atrito estático. / The relative movement among flat surfaces in contact is common for many engineering projects. During the operation of many mechanisms, friction problems are identified as a main obstacle to the successful performance of them. In this study the influence of nominal pressure contact on static friction between steel surfaces (ABNT 1020 and 1045) and glass plate is evaluated. The specimens‘ surfaces were obtained by means of a manufacturing process classified as machining with undefined tool – tangential plane grinding. The specimens were constituted by two groups: the group A (type cup – ABNT1010) and the group B (type compact – ABNT1045). All specimens were characterized with respect to surface roughness, using a 3-D optical non-contact profilometer. For static friction measurements, an inclined plan system was used, with an automated detection of movements of specimens along time. The nominal contact pressure not has any effect on the values of static friction coefficient. Since then, a possible effect of surface roughness on friction was investigated. The spectral moments m0, m2 and m4, and the bandwidth parameter, Alpha (α), were calculated from the 3-D roughness parameters, and this latter was correlated with static friction coefficient. Within the analyzed parameters: Sq, Sdq and Sds, the Sq parameter presented the largest discrepancy within the sampling data. Based on the statistical analysis of variance, with a confidence level of 5%, of Sq parameter, the specimens were relocated into 4 groups, for which we calculated alpha parameter. Considering these groups, we demonstrated that the alpha parameter affected the static friction coefficient, that is, the higher this parameter, the greater the static friction coefficient.

A fabricação de moldes e matrizes são ricas em detalhes e geometrias complexas, exigindo tecnologias mais inovadoras e precisas. Um dos processos que se destaca na fabricação de moldes e matrizes, é o de eletroerosão por penetração (Electrical Discharge Machining - EDM). A usinagem por descargas elétricas é classificada como um processo de fabricação de geometria não definida, onde a remoção de material é realizada por repetidas descargas elétricas entre dois eletrodos eletricamente condutores. O desgaste da ferramenta é um dos principais parâmetros de medida no desempenho da usinagem por EDM. O maior problema ocasionado pelo desgaste de canto do eletrodo é a mudança de geometria da ferramenta no decorrer da usinagem, alterando a tolerância geométrica e o dimensional da cavidade. O presente trabalho propõe avaliação dimensional do desgaste de canto do eletrodo, no decorrer da usinagem do processo de EDM, variando o ângulo de superfície frontal do eletrodo. Outro propósito é a criação de um índice, chamado de taxa de arredondamento, que leva em consideração as áreas de desgaste de canto do eletrodo em função da área removida de material da peça. Os resultados mostraram que os eletrodos de cobre, cobre tungstênio e grafite, tem um grande crescimento de raio de canto no inicio da usinagem, estabilizando esses valores com tempo maiores de processo. O ângulo de superfície frontal do eletrodo influência diretamente no desgaste de canto do eletrodo. Os eletrodos de grafite não apresentaram comportamento de arredondamento de desgaste de canto durante os ensaios. Para o índice de taxa de arredondamento os eletrodos de cobre tungstênio tiveram o menor valor apresentado na usinagem do AISI H13. / The manufacture of molds and dies are rich in detail and complex geometries, requiring more innovative and precise technologes. One of the processes that stands out in the manufacture of molds and dies, is to EDM by penetration (Electrical Discharge Machining - EDM). The cutting by electrical discharge is classified as a non-defined geometry manufacturing process where material removal is carried out by repeated electrical discharge between two electrodes electrically conductive. The tool wear is a major measurement parameters in machining performance by EDM. The biggest problem caused by the electrode corner wear is the tool geometry change during the machining by changing the geometric tolerance and dimensional cavity. This paper proposes dimensional evaluation of the electrode corner wear, during the machining of the EDM process, varying the front surface of the electrode angle. Another purpose is to create an index, called rounding rate, which takes into account the areas of electrode corner wear due to the removed area of the workpiece material. The results showed that the copper electrode, copper tungsten and graphite, has a large corner radius growth at the beginning of machining, stabilizing these values with higher process time. The front surface of the electrode angle influence directly on the electrode corner wear. Graphite electrodes showed no corner wear rounding behavior during the tests. For rounding rate index tungsten copper electrodes had the lowest value presented in the machining of AISI H13.

A fabricação de moldes e matrizes são ricas em detalhes e geometrias complexas, exigindo tecnologias mais inovadoras e precisas. Um dos processos que se destaca na fabricação de moldes e matrizes, é o de eletroerosão por penetração (Electrical Discharge Machining - EDM). A usinagem por descargas elétricas é classificada como um processo de fabricação de geometria não definida, onde a remoção de material é realizada por repetidas descargas elétricas entre dois eletrodos eletricamente condutores. O desgaste da ferramenta é um dos principais parâmetros de medida no desempenho da usinagem por EDM. O maior problema ocasionado pelo desgaste de canto do eletrodo é a mudança de geometria da ferramenta no decorrer da usinagem, alterando a tolerância geométrica e o dimensional da cavidade. O presente trabalho propõe avaliação dimensional do desgaste de canto do eletrodo, no decorrer da usinagem do processo de EDM, variando o ângulo de superfície frontal do eletrodo. Outro propósito é a criação de um índice, chamado de taxa de arredondamento, que leva em consideração as áreas de desgaste de canto do eletrodo em função da área removida de material da peça. Os resultados mostraram que os eletrodos de cobre, cobre tungstênio e grafite, tem um grande crescimento de raio de canto no inicio da usinagem, estabilizando esses valores com tempo maiores de processo. O ângulo de superfície frontal do eletrodo influência diretamente no desgaste de canto do eletrodo. Os eletrodos de grafite não apresentaram comportamento de arredondamento de desgaste de canto durante os ensaios. Para o índice de taxa de arredondamento os eletrodos de cobre tungstênio tiveram o menor valor apresentado na usinagem do AISI H13. / The manufacture of molds and dies are rich in detail and complex geometries, requiring more innovative and precise technologes. One of the processes that stands out in the manufacture of molds and dies, is to EDM by penetration (Electrical Discharge Machining - EDM). The cutting by electrical discharge is classified as a non-defined geometry manufacturing process where material removal is carried out by repeated electrical discharge between two electrodes electrically conductive. The tool wear is a major measurement parameters in machining performance by EDM. The biggest problem caused by the electrode corner wear is the tool geometry change during the machining by changing the geometric tolerance and dimensional cavity. This paper proposes dimensional evaluation of the electrode corner wear, during the machining of the EDM process, varying the front surface of the electrode angle. Another purpose is to create an index, called rounding rate, which takes into account the areas of electrode corner wear due to the removed area of the workpiece material. The results showed that the copper electrode, copper tungsten and graphite, has a large corner radius growth at the beginning of machining, stabilizing these values with higher process time. The front surface of the electrode angle influence directly on the electrode corner wear. Graphite electrodes showed no corner wear rounding behavior during the tests. For rounding rate index tungsten copper electrodes had the lowest value presented in the machining of AISI H13.