Strong demands for smaller, cheaper, and multifunction wireless systems have put very stringent requirements on passive devices, such as inductors and capacitors. This is especially true considering the size and weight of most radio frequency (RF) transceivers are mainly due to passives. RF micro-electro-mechanical-systems (MEMS) passives are addressing this issue by offering lower power consumption and losses, higher linearity and quality (<i>Q</i>)-factors, potential for integration and miniaturization, and batch fabrication. These advantages position RF MEMS passives as good candidates to replace conventional passives. Further, they also open an opportunity for using the passives as building blocks for lumped element-based RF circuits (e.g. Flters, couplers, etc.) which could replace the more-bulky distributed-element circuits.<p> This thesis presents the design, simulation, fabrication using the deep X-ray lithography process, and testing of thick-metal RF inductors and their applications to lumped-element low-pass Filter (LPF) circuits. The 70-um tall single-turn loop inductors are structurally compatible to a pre-existing RF MEMS capacitor concept and allow the two device types to be fabricated together. This compatibility issue is crucial if they would be used to construct more complex RF circuits.<p> At a 50-Ohm inductive reactance point, test results show <i>Q</i>-factors of 17- 55, self-resonant frequencies (SRF) exceeding 11 GHz, and nominal inductances of 0.4- 3 nH for 1-loop inductors and <i>Q</i>-factors of 11- 42, SRFs of 4- 22 GHz, and inductances of 0.8- 5.5 nH for 2-loop inductors. Further, test results reveal that high conductivity metals improve the <i>Q</i>-factors, and that low dielectric-constant substrates increase the SRFs.<p> In terms of LPFs, measurements show that they demonstrate the expected third-order Chebyshev response. Two nickel Filters on a quartz glass substrate show a 0.6-dB ripple with 3-dB frequencies (<i>f</i>-3dB) of 6.1 GHz and 11.9 GHz respectively. On an alumina substrate, they exhibit a 1.4-dB ripple with <i>f</i>-3dB of 5.4 GHz and 10.6 GHz respectively. The filters are 203- 285 um tall and feature 6- 6.5 um wide capacitance air gaps. These dimensions are different than the original designs and the filter performances were shown to be somewhat sensitive to these discrepancies. Compared to a distributed approach, the lumped-element implementations led to an area reduction of up to 95%.

Strong demands for smaller, cheaper, and multifunction wireless systems have put very stringent requirements on passive devices, such as inductors and capacitors. This is especially true considering the size and weight of most radio frequency (RF) transceivers are mainly due to passives. RF micro-electro-mechanical-systems (MEMS) passives are addressing this issue by offering lower power consumption and losses, higher linearity and quality (<i>Q</i>)-factors, potential for integration and miniaturization, and batch fabrication. These advantages position RF MEMS passives as good candidates to replace conventional passives. Further, they also open an opportunity for using the passives as building blocks for lumped element-based RF circuits (e.g. Flters, couplers, etc.) which could replace the more-bulky distributed-element circuits.<p> This thesis presents the design, simulation, fabrication using the deep X-ray lithography process, and testing of thick-metal RF inductors and their applications to lumped-element low-pass Filter (LPF) circuits. The 70-um tall single-turn loop inductors are structurally compatible to a pre-existing RF MEMS capacitor concept and allow the two device types to be fabricated together. This compatibility issue is crucial if they would be used to construct more complex RF circuits.<p> At a 50-Ohm inductive reactance point, test results show <i>Q</i>-factors of 17- 55, self-resonant frequencies (SRF) exceeding 11 GHz, and nominal inductances of 0.4- 3 nH for 1-loop inductors and <i>Q</i>-factors of 11- 42, SRFs of 4- 22 GHz, and inductances of 0.8- 5.5 nH for 2-loop inductors. Further, test results reveal that high conductivity metals improve the <i>Q</i>-factors, and that low dielectric-constant substrates increase the SRFs.<p> In terms of LPFs, measurements show that they demonstrate the expected third-order Chebyshev response. Two nickel Filters on a quartz glass substrate show a 0.6-dB ripple with 3-dB frequencies (<i>f</i>-3dB) of 6.1 GHz and 11.9 GHz respectively. On an alumina substrate, they exhibit a 1.4-dB ripple with <i>f</i>-3dB of 5.4 GHz and 10.6 GHz respectively. The filters are 203- 285 um tall and feature 6- 6.5 um wide capacitance air gaps. These dimensions are different than the original designs and the filter performances were shown to be somewhat sensitive to these discrepancies. Compared to a distributed approach, the lumped-element implementations led to an area reduction of up to 95%.

The thick-shelled river mussel (Unio crassus) is a red listed species classified as Endangered (EN) and is also considered within the Habitats Directive. The distribution in Sweden is fragmented and it is mostly occurring in the south eastern parts. We investigated the presence of Unio crassus in a section of the stream Storån, Östergötland County, from Falerum to the inflow into Lake Åkervristen. The environmental parameters investigated were water depth, bottom substrate, shading, water velocity and the slope over the water surface. In this thesis I have focused mainly on water depth and shading, comparing sites with and without mussels. In addition, I used a multivariate PCA analysis to evaluate all parameters together. The water depth was significantly larger in habitats with mussels than in those without. Shading varied from 5 to 80 %, but there was no significant difference between habitats with and without mussels. There was no correlation between water depth and mussel density and not between shading and mussel density either. The multivariate PCA analysis showed that the habitats with and without mussels were different from with regard to the PC1 axis, which included water depth, bottom substrate and water velocity. Alone, the water depth is not enough to predict the presence of Unio crassus in the stream, and it is likely that more parameters need to be considered.  Previous work indicate that the more parameters and habitats that are investigated, the more confident results can be stated of which habitats Unio crassus prefer.

The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t&gt;2.54, p&lt;0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size &lt;4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t&gt;2.54, p&lt;0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size &lt;4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

Biological hydrogen production through integration of dark and photo-fermentation by using biomass is a promising alternative for energy supply problems. The main purpose of this study was to investigate photobiological H2 production by the purple non-sulfur (PNS) bacteria Rb. capsulatus on dark fermentation effluent of sugar beet thick juice (DFESBTJ). Presence of NH4+ in effluents is an important parameter since NH4+ inhibit the nitrogenase enzyme activity. Therefore, the influence of different NH4+ concentrations in the DFESBTJ by removing using natural zeolite clinoptilolite on photofermentative H2 production were studied using Rb. capsulatus DSM1710 and Rb. capsulatus YO3 (hup-). Also, the effect of EtOH concentrations (between 6.25 and 200 mM) in the defined medium on H2 production were studied using both bacterial strains since EtOH is a possible by-product of dark fermentation process. The experiments were carried out in small scale bottle photobioreactors (PBRs) and outdoor panel PBR (4 L). H2 productivity of 1.12 mmol/Lc/h was attained over 15 days of operation for panel PBR. The results showed that the zeolite was effective in removing NH4+ from the DFESBTJ as its concentration decreased by 95% after treatment. In both bacterial strains, an increase in the maximum productivities and molar H2 yields was observed with the decrease in NH4+concentrations. There was no significant effect of EtOH on H2 production except the inhibition at 200 mM. The main conclusions were that both bacterial strains could effectively utilize the DFESBTJ for growth and H2 production, therefore facilitating the integration of the dark and photo-fermentation for sustainable biohydrogen production.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 86-95.

In the past decade, there has been an increased interest in magnetostrictive materials for micro actuators and sensors. Of particular importance are the Fe₂R intermetallics, where R = Tb, Dy. In this study, films of Tb[subscript 0.3]Dy[subscript 0.7]Fe[subscript 1.92] were prepared by three laser processing techniques (pulsed laser deposition, flat plate ablation and laser ablation of microparticles) to explore the effect of processing parameters on particle size, crystallinity and magnetic properties. The laser used in the experiments was a KrF laser with a 12 ns pulse width. Pulsed laser deposition of an alloyed target in vacuum produces dense amorphous films with the similar composition to the target, low coercivity (46 Oe) and good magnetostriction ([lambda][subcript two horizontal lines] = 305 ppm at 2300 Oe). Flat plate ablation and laser ablation of microparticles produced amorphous nanoparticles at 1 atm. The particles were subsequently jet deposited onto substrates to form thick films. Nanoparticle films produced by flat plate ablation resulted in oxidized and segregated particles due to extended, non-uniform plume expansion, laser target modification, and open porosity. Laser ablation of microparticles produced thick films with M[subscript s] = 13.8 emu/g. Two types of annealing treatments were performed to close porosity and increase Youngs modulus. Annealing of LAM films at temperatures up to 700°C in-situ and 950°C in a reducing atmosphere did not result in coarsening of the particles or crystallization of the Laves phase due to the core-shell structure of nanoparticles (rare earth oxide shell, Fe rich core) brought about by oxidation-induced segregation.

Titanium based alloys reinforced uniaxially with silicon carbide fibres (Ti/SiC) are advanced and innovative materials for aerospace vehicles. To avoid potential problems, these new materials should be extensively tested and analyzed before application. This research focuses on experimental fracture toughness study on 0.5 mm thick Ti/SiC composite materials for aerospace applications. The fracture toughness tests are mainly based on BS 7448 with some modifications for transversely isotropic behaviour of the composite materials. By loading on specimens in the direction perpendicular to the fibre axis, three critical values of fracture toughness parameters characterizing fracture resistance of material, plane strain fracture toughness [Plane strain fracture toughness }, critical crack tip opening displacement [Critical crack tip opening displacement ] and critical J-integral [Critical at the onset of brittle crack extension or pop-in when Δa is less than 0.2 mm. ]are measured for two kinds of titanium alloy specimens and three kinds of Ti/SiC composites specimens. The values of [Provisional value of Plane strain fracture toughness ] obtained from the fracture toughness tests are not valid [Plane strain fracture toughness ] for these materials, since the thickness of specimens is insufficient to satisfy the minimum thickness criterion; however, the results could be used as particular critical fracture toughness parameter for 0.5 mm thick structures of the materials. The valid values of [Critical J at the onset of brittle crack extension or pop-in when Δa is less than 0.2 mm. ] and [Critical crack tip opening displacement ] could be used as fracture toughness parameters for all thickness of structures of the materials. The results also show that: fracture toughness of the titanium alloys decreases dramatically after being unidirectional reinforced with SiC fibre, which is mainly triggered by poor fibre/matrix bonding condition. Moreover, Ti-Al3-V2.5 reinforced with 25% volume fraction SiC fibre performs better than the other two composites in fracture resistance.

Šio darbo tikslas buvo ištirti Galaktikos storojo disko žvaigždžių cheminę evoliuciją. Devynių F-G-K spektrinės klasės žvaigždžių spektrai buvo gauti SOFIN spektrografu su Šiaurės šalių teleskopu. Iš spektrų nustačiau pagrindinius žvaigždžių atmosferų fizikinius parametrus: efektinę temperatūra Teff., gravitacinį pagreitį žvaigždės paviršiuje lg g, mikroturbulencijos greitį vt. ir deguonies, geležies, α, r- ir s-procesų elementų gausas devyniose storojo Galaktikos disko žvaigždėse. Rezultatus palyginau su kitų mokslininkų grupių darbais: tai Tautvaišienės ir kt. darbas (2001 m.); Bensby ir kt. darbai (2004, 2005, 2007 m.); Reddy ir kt. darbas (2006 m.). Geležies gausai [Fe/H] esant intervale nuo ≈ –0,9 iki ≈ –0,3 dešimtųjų žvaigždės, pasižyminčios storojo Galaktikos disko kinematika, yra turtingesnės deguoniu, magniu ir alfa-proceso elementais, nei plonojo disko žvaigždžių populiacija. Kitų cheminių elementų gausos storajame ir plonajame Galaktikos diskų žvaigždėse yra panašios. / The aim of this research is to study the Galactic thick disk chemical evolution. Using high-resolution spectra I have derived the chemical composition of a sample of Galactic thick disk stars. High resolution spectra of 9 F-G-K spectral type stars in the Galactic thick disk have been obtained by the SOFIN spectrograph on the Nordic Optical Telescope. From these stellar spectra I determined the basics stellar atmosphere parameters: effective temperatures Teff [K], surface gravities lg g, microturbulent velocities vt [km/s], and abundances of oxygen, iron, α, r- and s-process elements in the Galactic thick disk. The results are similar to those of other investigations: Tautvaišienė et al., 2001; Bensby et al., 2004, 2005, 2007; Reddy et al., 2006. For a given [Fe/H] the stars with kinematics typical of the thick disk are more enriched in oxygen and α- process elements (Mg, Si, Ca, Ti) than the stars with kinematics typical of the thin disk. The abundance of other elements (Al, Na, Cr, Ni, V, Sc, Mn, Co, Cu, Y, Zr, Ba, La and Nd) is similar for the two disks. The abundance ratios of oxygen, α, r- and s-process elements to iron provide further evidence that the thick disk star population have a different chemical history compared to the thin disk. The stars formation rate was probably higher in the Galactic thick disk than in the Galactic thin disk.