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Thesis (M. Sc.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Carbonate reservoirs are usually diffcult to map and identify in seismic sections due to their complex structure, lithology and diagenetic frabrics. The Midland Basin, located in the Permian Basin of West Texas, is an excellent example of these complex carbonate structures. In order to obtain a better characterization and imaging of the carbonate buildups, an acoustic impedance inversion is proposed here. The resolution of the acoustic impedance is the same as the input seismic data, which is greatly improved with the addition of the low frequency content extracted from well data. From the broadband volume, high resolution maps of acoustic impedance distributions were obtained, and therefore the locations of carbonate buildups were easily determined. A correlation between acoustic impedance and porosity extracted from well data shows that areas with high acoustic impedance were correlated with low porosity values, whereas high porosities were located in areas of low acoustic impedance. Theoretical analyses were performed using the time-average equation and the Gassmann equation. These theoretical models helped to understand how porosity distributions affect acoustic impedance. Both equations predicted a decrease in acoustic impedance as porosity increases. Inversion results showed that average porosity values are 5% [plus or minus] 5%, typical for densely cemented rocks. Previous studies done in the study area indicate that grains are moderately to well-sorted. This suggests that time-average approximation will overestimate porosity values and the Gassmann approach better predicts the measured data. A comparison between measured data and the Gassmann equation suggests that rocks with low porosities (less than 5%) tend to have high acoustic impedance values. On the other hand, rocks with higher porosities (5% to 10%) have lower acoustic impedance values. The inversion performed on well data also shows that the fluid bulk modulus for currently producing wells is lower than in non-productive wells, (wells with low production rates for brine and hydrocarbons), which is consistent with pore fluids containing a larger concentration of oil. The acoustic impedance inversion was demonstrated to be a robust technique for mapping complex structures and estimating porosities as well. However, it is not capable of differentiating different types of carbonate buildups and their origin.

A theoretical approach to calculating impedance of metallicmagnetic/conductor layered structures is developed. Thefrequency range considered extends to the ferromagneticresonance region of soft magnetic films (of the order of 1GHz). The analysis includes the effects of screening of thehigh frequency fields by eddy currents as well as the dynamicsand relaxation of the magnetization of the ferromagneticsub-system. Analytical expressions for the impedance as afunction of frequency and material parameters and geometry ofmagnetic sandwich stripes are obtained. Two maincross-sectional layouts are considered: amagnetic/conductor/magnetic sandwich stripe with and withoutflux closure at the edges along the stripe length - with andwithout the magnetic film enclosing the conductor strip. Theimportance of good magnetic flux closure for achieving largespecific inductance gains and high efficiency at GHzfrequencies is emphasized. The theoretical results obtained were used to design andanalyze magneticfilm inductors produced using iron nitridealloy films. Patterned sandwiches, consisting of two Fe-N filmsenclosing a conductor film made of Cu, were fabricated onoxidized Si substrates using lift-off lithography. Theinductors exhibited a 2-fold specific inductance enhancement at1 GHz. The magnetic contribution to the total flux in thenarrow devices was less then predicted theoretically, which wasattributed to hardening of the magnetic material at the edgesof the strip leading to incomplete flux closure. Material anddesign issues important for further improving the performanceof the devices are discussed.

Along with the rapid growth of the nanotechnology, nanoparticles (NPs) have found many applications in commercial products. However, there are only a few studies on the toxicity and the environmental effects of NPs in biological systems. <p>In the study described in this thesis, I have used water-soluble Au NPs that were synthesized using the Brust method and then modified by small molecules. I explored the interactions of these modified Au NPs with self-assembled monolayer films on gold surfaces.<p>Three types of self-assembled monolayer (SAM) modified gold surfaces were used in this study. The surfaces had SAMs that could be positively or negatively charged or carry no charge, or be able to engage in hydrogen bonding. <p>Cyclic voltammetry (CV) was used to characterize SAMs of disulfide-glycine conjugate, disulfide-aspartic conjugate, and 11-mercaptoundecanoic acid (MUA) on gold surface electrodes. The possible interactions of Au NPs with the disulfide-aminoacid conjugates and alkanethiol modified surfaces were evaluated by cyclic voltammetry and by electrochemical impedance spectroscopy (EIS). An apparent decline in current density observed in CV along with an electron transfer resistance increase in EIS measurements upon exposure of the films to the MUA-modified anionic Au NPs clearly indicate interactions of the NPs with the films. Likewise, upon exposure of the films to cationic NPs, electron transfer resistance decreases dramatically in EIS experiments. In addition, the current increase in CV measurements provided further evidences for the interactions. The interactions between modified Au NPs and the SAMs were investigated in more detail by infrared spectroscopy and by employing quartz crystal microbalance. These studies clearly showed that upon exposure of these SAM films to the water-soluble Au NPs, significant changes occur. As would be expected for the adsorption of the Au NPs onto the SAMs, the weight of the film increased due to the addition of the NPs on the surface. Moreover, there are significant increases in the carbonyl stretching vibration at 1735 cm-1 along with the appearance of the amide hydrogen stretching band, between 3160-3380 cm-1, which indicate the adsorption of Gly-CSA modified Au NPs onto the MUA film.

Along with the rapid growth of the nanotechnology, nanoparticles (NPs) have found many applications in commercial products. However, there are only a few studies on the toxicity and the environmental effects of NPs in biological systems. <p>In the study described in this thesis, I have used water-soluble Au NPs that were synthesized using the Brust method and then modified by small molecules. I explored the interactions of these modified Au NPs with self-assembled monolayer films on gold surfaces.<p>Three types of self-assembled monolayer (SAM) modified gold surfaces were used in this study. The surfaces had SAMs that could be positively or negatively charged or carry no charge, or be able to engage in hydrogen bonding. <p>Cyclic voltammetry (CV) was used to characterize SAMs of disulfide-glycine conjugate, disulfide-aspartic conjugate, and 11-mercaptoundecanoic acid (MUA) on gold surface electrodes. The possible interactions of Au NPs with the disulfide-aminoacid conjugates and alkanethiol modified surfaces were evaluated by cyclic voltammetry and by electrochemical impedance spectroscopy (EIS). An apparent decline in current density observed in CV along with an electron transfer resistance increase in EIS measurements upon exposure of the films to the MUA-modified anionic Au NPs clearly indicate interactions of the NPs with the films. Likewise, upon exposure of the films to cationic NPs, electron transfer resistance decreases dramatically in EIS experiments. In addition, the current increase in CV measurements provided further evidences for the interactions. The interactions between modified Au NPs and the SAMs were investigated in more detail by infrared spectroscopy and by employing quartz crystal microbalance. These studies clearly showed that upon exposure of these SAM films to the water-soluble Au NPs, significant changes occur. As would be expected for the adsorption of the Au NPs onto the SAMs, the weight of the film increased due to the addition of the NPs on the surface. Moreover, there are significant increases in the carbonyl stretching vibration at 1735 cm-1 along with the appearance of the amide hydrogen stretching band, between 3160-3380 cm-1, which indicate the adsorption of Gly-CSA modified Au NPs onto the MUA film.

In March 2007 five satellites were launched as part of the NASA mission THEMIS. The aim of the mission is to answer the unknown questions regarding the onset of substorms. THEMIS data has also been used within other research fields. Today many scientists aim to investigate wave phenomena, such as whistler waves, wave interactions in the radiation belts and general turbulence in the magnetosphere and the solar wind. These processes occur at intermediate frequencies (a few hundreds of Hertz). Correct and reliable results require good knowledge of the frequency response,  the so called transfer function, for the electric field instrument (EFI). Post-launch calibrations have given good knowledge of the instrument's response at high and low frequencies. However, at intermediate frequencies (50-3000 Hz) the transfer function has only been determined via calculations/simulations and not yet obtained from data collected in space. Moreover, the transfer function changes substantially in this range, as the instrument transitions from a resistive low-frequency coupling to a capacitive high-frequency coupling. The transition is known as the RC roll-off. In this thesis, data from different regions and with different electrical settings have been analyzed to estimate the EFI sensors' sheath impedance and transfer function. Data have been collected during July 2009 and March 2011. From the first period, I-V curves where extracted for four different regions (i.e. with different plasma conditions) and their associated sheath impedance calculated. I-V curves are graphical representations of how the voltage differs with the changed bias current. From the sheath impedance and the measured free-space capacitance the RC roll-off can been directly calculated. An experiment was also conducted in March 2011 where the instrument was run in a special mode designed to measure the relative transfer function with the probes run at different bias setting, yielding different sheath impedances. The analysis of the I-V curves and relative transfer function show similar results, which clearly differ from the earlier believed values. Values for the sheath impedance are lower (4-6 MΩ) than the expected (30 MΩ) and depend on the usher setting. The usher is an electronic device which should shield the sensor from the photoelectron produced by illumination of the preamplifier. This lower sheath resistance implies higher than expected RC roll-off frequency, a result which is confirmed by the results from the relative transfer function. The roll-off is between 2-3 kHz, compared to the 400-500 Hz assumed prior to this study based on the assumption of a sheath impedance of around 30 MΩ.

Interconnect modeling plays an important role in design and verification of VLSI circuits and packages. For low frequency circuits, great advances for parasitic resistance and capacitance extraction have been achieved and wide varieties of techniques are available. However, for high frequency circuits and packages, parasitic inductance and impedance extraction still poses a tremendous challenge. Existing algorithms, such as FastImp and FastHenry developed by MIT, are slow and inherently unable to handle multiple dielectrics and magnetic materials. In this research, we solve three problems in interconnect modeling for high frequency circuits and packages. 1) Multiple dielectrics are common in integrated circuits and packages. We propose the first Boundary Element Method (BEM) algorithm for impedance extraction of interconnects with multiple dielectrics. The algorithm uses a novel equivalentcharge formulation to model the extraction problem with significantly fewer unknowns. Then fast matrix-vector multiplication and effective preconditioning techniques are applied to speed up the solution of linear systems. Experimental results show that the algorithm is significantly faster than existing methods with sufficient accuracy. 2) Magnetic materials are widely used in MEMS, RFID and MRAM. We present the first BEM algorithm to extract interconnect inductance with magnetic materials. The algorithm models magnetic characteristics by the Landau Lifshitz Gilbert equation and fictitious magnetic charges. The algorithm is accelerated by approximating magnetic charge effects and by modeling currents with solenoidal basis. The relative error of the algorithm with respect to the commercial tool is below 3%, while the speed is up to one magnitude faster. 3) Since traditional interconnect model includes mutual inductances between pairs of segments, the resulting circuit matrix is very dense. This has been the main bottleneck in the use of the interconnect model. Recently, K = L-1 is used. The RKC model is sparse and stable. We study the practical issues of the RKC model. We validate the RKC model and propose an efficient way to achieve high accuracy extraction by circuit simulations of practical examples.

In this study, we design and fabricate novel tag antennas, which can be used on the metallic surface for radio frequency identification systems. We first focus on the effects when the antenna is placed on the metallic surface. Based on the simulation results, we investigate how the parameters of the antennas are affected. The helps us find solutions to reduce the effects when the antennas are placed on the metallic surface. In order to conform to the IC chips of RFID and reduce the influence of metal objects, we use the structure of the dipole antenna is used as the basis of the novel tag antenna design. And we employ the high impedance surface periodic structure which behaves similarly to a perfect magnetic conductor in the design of the novel tag antenna. The novel tag antenna is able to work normally when it was attached on the surface of the carton or metallic object. Finally, the tag antenna is fabricated and measured in a chamber. The measured results agree with simulated ones well.

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