Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 293-299).

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 170).

Thesis (MS)--Montana State University--Bozeman, 2010. / Typescript. Chairperson, Graduate Committee: Rick L. Lawrence. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 158-163).

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

A typical "white" LED comprises a blue source and one or more phosphors, which down-convert the high energy blue light to longer wavelengths. The resultant "mixture" of wavelengths (predominantly residual blue light from the source and yellow and red from the phosphors) produces white light. Typically, phosphors are coated directly (proximally) onto the blue source. This work differs from the conventional approach by incorporating phosphors in a secondary optic, which is remote from the source. This has the advantages of being able to recover the source LED and to change the output wavelength by stacking optics that contain different levels of different phosphors, or by mixing different phosphors into a single optic. The work has created a range of secondary optics that contain one or more phosphors at relatively low levels of addition (1%-4% by weight) in thermoplastic and thermosetting matrices including polystyrene, poly(methylmethacrylate) and silicone. The phosphors are based on a range of YAGs and nitrides. The secondary optics were manufactured by injection moulding (thermoplastics) or casting (thermosets) and were used singly or in stacked layers to down-convert light from a royal blue (450 nm) LED source to produce a range of "white" light sources. Both injection moulding and casting are relatively inexpensive and commonly encountered processes. The optical performance of these optics was measured by Spectral Power Distribution (SPD), chromaticity, Colour Temperature (CCT) and Colour Rendering Index (CRI). CCT and CRI values ranged from 3000K to 6500K and (80-95) depending on the phosphor composition. Measurements were also carried out on the long-term performance of the secondary optics and these showed little or no change after 24 months continuous and intermittent exposure.

Field measures were combined with synthetic aperture radar (SAR) images to evaluate the use of radar for estimating temporal biomass and mapping of aquatic vegetation in the lower Amazon. A SAR-based methodology was developed for quantification of the annual net primary productivity (NPP) of aquatic vegetation. The predictable monomodal flooding cycle of the floodplain is the primary control of the growth pattern of the aquatic vegetation. The total biomass increased steadily from November to August following the hydrological cycle. However, the above water biophysical properties of the canopy remained constant all year around, except in November. By November, when the water level started to rise, new leaves and nodes were formed; the backscattering values were on average -12 and -l4dB for RADARS AT and JERS-1, respectively. By April, a full canopy was developed, remaining constant due to the high turn over rate of leaves. By August, the water level quickly receded, the senescent stage began, the plant water content decreased, and the stems bent, changing from an almost vertical orientation. From April onwards the backscattering coefficientes were on average -7 and -9.5 dB, respectively. The spatial variability of the canopy biophysical properties was detectable with radar data. Significant correlation existed between backscattering coefficients and above water dry biomass, height, and percentage of canopy cover. The logarithmic relationship between backscattering coefficients and biomass suggested that ( 1 ) at low biomass, high transmissivity of the microwave radiation through the vegetation canopy occurred and the backscattering was a result of quasi-specular reflection of both C and L bands and a minor contribution of canopy volume scattering from C band; (2) at intermediate levels of biomass, moderate changes in backscattering values occurred and the backscattering saturation point was reached at 470, 660, and 620 gm⁻², for C band, L band, and the index, respectively; and (3) at high biomass, the transmissivity of C and L band radiation was equally attenuated and backscattering approached similar values for both. The derived index [special characters omitted] combines the capabilities of both C and L bands providing an empirical model for estimating above water biomass [special characters omitted] with the highest R² (0.67), the lowest root mean square error (34%), and an intermediate saturation point. The despeckled composite SAR images (C and L bands from the same season) were classified using a region-based approach. Complementary information of the satellites yielded classification accuracy higher than 95% for vegetated areas of the floodplain. The seasonal thematic classification yielded an estimate of the length of inundation of different regions of the floodplain. Regions under flooded conditions of at least 300 days yr⁻¹ were colonized predominantly by the aquatic vegetation, Hymenachne amplexicaulis; the tree-like aquatic plant, Montrichartia arborescens; and some shrub-like trees. Secondary colonizers such as Cecropia sp., Pseudobombax munguba, and Astrycaryum jauari, which are tall well-developed flooded forest, colonized regions with inundation periods of approximately 150 days yr⁻¹. Climax forest colonized regions with inundation periods of approximately 60 days yr⁻¹. The combination of the mapped area of seasonal aquatic vegetation with the SAR derived-biomass estimation allowed the calculation of the seasonal total biomass. By November, the new generation of aquatic vegetation started to develop; total biomass in the area was O.l x lO⁻¹² g. The steady growth of vegetation yielded a total biomass of 1.5 x 10⁻¹² g in an area of 395 km² in May. From May onwards, with the water receding, some plants detached from the sediment and were carried towards the Amazon River. Consequently, by August, both area and total biomass decreased to 281km² and 5 x lO⁻¹¹g, respectively. Any estimate of total biomass had a margin of error of at least 18%. After correction for seasonal biomass loss, the estimated annual NPP was 6350gm⁻² or 4.l x l0⁻¹²g for the entire area. Despite the smaller dimensions and the C3 photosynthetic pathway of the dominant H. amplexicaulis, its estimated productivity was comparable to the values reported for the most productive aquatic vegetation of the Amazon floodplain, and other aquatic plants colonizing wetlands worldwide. The estimated NPP of the aquatic vegetation yielded a total carbon uptake of 1.9 x l0⁻¹² g C yr⁻¹. Calculations based on the estimated area of each habitat of the floodplain, and the productivity data suggested in the literature, resulted in a net carbon productivity from flooded forest, phytoplankton, and periphyton of 0.35 x l0⁻¹²gC yr⁻¹, 0.22 x l0⁻¹²g C yr⁻¹, 0.07 x 10⁻¹² g C yr⁻¹, respectively. The total combined autochthonous annual net productivity of the study area was 2.5 x 10⁻¹² g C, of which 75% was from C3 aquatic plants. This study represents the first attempt to develop a method to use SAR and field data for estimating spatial and temporal variations in biomass of aquatic vegetation from a natural floodplain. / Graduate

No description available.

<p> Mid-infrared emissivity spectra are an extremely useful tool for determining bulk surface composition of planetary bodies. Our current interpretation of these spectra relies primarily on studies of spectra acquired in a terrestrial environment, which do not exhibit the same behavior as spectra measured on the surface of airless bodies like the Moon. From previous studies, we know that the environmental conditions in which mid-infrared spectra are measured affect the position and spectral contrast of spectral features used in compositional identification and analysis. The unique thermal environment within the upper 100s of microns of lunar regolith results in an anisothermal emissivity spectrum that cannot be directly compared to typical isothermal spectral libraries. It is also known that physical attributes of the material, such as particle size, will affect spectral features; however, this has not been studied in an airless environment. The second chapter of this dissertation is therefore dedicated to understanding the changes to mid-infrared spectra acquired under a simulated lunar environment due to particle size variation. </p><p> An additional aspect of the lunar environment not seen on Earth is the process of space weathering. Space weathering is the amalgamation of exposure to solar and cosmic radiation as well as micrometeoroid bombardment resulting in physical, chemical, and optical alteration of lunar regolith. For this work, I focus on the resulting albedo decrease in mature regolith, i.e., regolith that has been exposed to space weathering for a substantial period of time. In Chapter 3, I focus on the mid-infrared spectral changes due to albedo on pure minerals measured under a simulated lunar environment, and Chapter 4 describes the effect of albedo on emissivity data from the Diviner Lunar Radiometer Experiment, the only current mid-infrared instrument in orbit around the Moon. </p><p> From this work, I determine that both particle size and albedo affect mid-infrared emissivity spectral features in ways that complicate mineral identification and show how our laboratory work can enable better interpretation of spectra from the Moon, as well as other airless bodies within our Solar System.</p><p>