In rapid wireless communication technology development environment, antennas, the interface among many wireless communications, are an indispensable component for wireless systems. Miniaturization and functionality stability (high tolerance to environmental variations) of the antenna are fast becoming the design trends in research and development of wireless communication systems. They are also the main objectives of this thesis. In the first part of this thesis, we designed two highly stable antennas, which can be used in notebook computers or tablet PCs. The antenna has self-balanced characteristics, where the environmental interference is minimized, in its performance/functionality and patterns. The first antenna design, which can be easily integrated into an RF front-end board, employed capacitive coupling, differential feed printed loop configurations. Comparing to the existing differentially fed antenna design, our designs are much more miniaturized: the antenna size was 13 mm ¡Ñ 27 mm, the ground size was 4.5 mm ¡Ñ 4.5 mm. Implemented on a low-cost FR4 board, the antenna reduced the leakage current formed on coaxial transmission line, due to the advantage of being differentially fed. The second antenna design, fed by coaxial cable (single-ended fed), and without a ground plane, excited only self-balanced modes. The radiation patterns of higher modes in this antenna design are complete and without side lobes. This antenna design also has wide bandwidth characteristics: at 2.4 GHz it had 380 MHz, and at 5.2 GHz it had 1270 MHz bandwidths of high tolerance (stability). The actual measurement validated our simulation results. In the second part, MIMO antennas were designed for 802.11n wireless standards with maximum transfer rates of up to 300 Mbps. First, we designed two small single antennas, which were applied later in MIMO antenna designs. The size of our MIMO antenna designs was only 19 mm ¡Ñ 30.3 mm. In MIMO antenna designs, we employed two methods to increase the isolation between the two MIMO antennas: one manipulated the ground plane size, in which the isolation reached 18.9 dB; the other utilized a decoupling metal, where the overall isolation reached 24.6 dB in all of the operating frequencies, with the best isolation being 31.4 dB. The frequency of the coupling/decoupling for the decoupling metal can be adjusted independently; thus not affecting the original resonant frequency and the return loss of the two MIMO antennas. Actual measurements conducted in the microwave chamber (Reverberation Chamber) have verified the channel capacity were effectively increased, the total radiation efficiencies were about 60%, and the effective diversity gain was about 7dB. The MIMO antenna designs can practically and easily applied in the USB dongles.

The St. Croix ground lizard, Ameiva polops, is a United States endangered species endemic to St. Croix, U.S. Virgin Islands. It was extirpated from St. Croix Proper by invasive mongooses, and remaining populations are on small, nearby cays. In the summer of 2008, as part of the recovery plan for this species, I worked in a multi-agency effort to translocate a population of A. polops to Buck Island Reef National Monument, U.S. Virgin Islands to focus on two main objectives: 1) examine the detection probability of A. polops and infer the consequences of it on population estimates; and 2) examine whether A. polops may deplete its prey base or alter the arthropod assemblage at the translocation site. We used a soft-release strategy for the translocation, in which 57 lizards were initially contained in a series of eight 10 m x 10 m enclosures in the habitat on Buck Island for monitoring. As part of the initial monitoring I conducted visual surveys through all enclosures, with the known number of lizards, to calculate the detection probability and to demonstrate how many individuals would be estimated using visual encounter surveys of this known population. Adjacent to enclosures housing A. polops were control enclosures, without A. polops, which I used to test whether the translocated lizards would impact their prey base over 6 weeks. I found that the detection probability of A. polops is very low (<0.25), which causes population sizes to be severely underestimated, even using some mark-resight techniques. My study of A. polops on the prey community indicated that the lizards generally had no effect on abundance or diversity of arthropods in general, though they may cause small changes for particular taxa. My results help corroborate other evidence that accuracy of population enumeration techniques needs to be improved in order to adequately understand the status of wildlife populations. Additionally, prey resources do not seem to be limiting A. polops in the short-term, and I expect the population will grow, expanding through Buck Island. Future monitoring will be carried out by the National Park Service using robust mark-resight techniques.

The alongshore variability of beach-dune systems and the response and recovery from extreme storms remains poorly understood. The height and extent of foredunes along barrier islands varies over a range of spatial scales, implying that during extreme storms, the beach-dune system should respond in different ways depending on the elevation and volume of the dunes relative to the storm surge. The purpose of this study is to use Ground-Penetrating Radar (GPR) and vibra-cores to investigate the internal structure of small, intermediate and large dunes along a 2.5 km transect of beach in Padre Island National Seashore, TX with particular attention to storm impacts. A series of dune normal and parallel GPR profiles were collected to capture the variation in beach-dune morphology at the three sites. Site locations were chosen along a transition from dissipative to intermediate beach states. Following the Sallenger (2000) storm impact model, the small dune is defined by low-lying topography that is susceptible to overwash and inundation depending on the size of the storm surge. The large dune is characteristic of the “collision regime”, while the intermediate dune represents a transition between “overwash” and “collision regimes”, with the underlying assumption that all three dunes would be impacted by the same level of surge during a single storm event. Results from the GPR survey suggest that each site contains a bright, laterally continuous radar reflector that is interpreted with the aid of the sedimentary data as an erosional layer. Different characteristic radar facies and sequence boundaries provide evidence as to how each dune evolved through and after the storm. Results from XRF scans and grain size analysis show a direct comparison between the GPR reflectors at the storm surface and spikes in calcium counts from XRF scans to distinct changes in grain size parameters at the same depth. It is argued that the location of each shell layer corresponds to a storm surface generated during a single storm, which means it is possible to interpret different recovery mechanisms. The presence of the storm layer across the backbeach and dunes provides evidence for the height and extent of the surge during the storm event. The data suggests that the small dune was overtopped by the surge, experiencing minimal erosion and recovery. The intermediate dune was completely eroded by the surge, but showed the greatest recovery of all the dune sites. The large dune was scoured at the base with marginal impact along its crest and shows minimal recovery after the storm. These results suggest that the evolution (i.e., transgression) of a barrier island varies considerably over short distances.

Abstract Whether an Open Area Test Site (OATS) is qualified is based on the Normalized Site Attenuation (NSA). The purpose is to eliminate the influence of Antenna Factor (AF). Usually the AF provided by the manufacturer adopts the Standard Site Method (SSM) and is quoted from measurements at a 10-m range. In practice, the AF varies with the measurement conditions. This uncertainly will translate into error in NSA measurements. Currently radiated electromagnetic interference measurement mostly adopts the broadband antennas, and LPDA is one of the antennas used extensively. However, the AF provided by the manufacturer does not consider shifts in the phase center of LPDA with frequency. In the meantime the radiation pattern of LPDA is different from that of a short dipole. The investigation of this thesis will focus on these two parts. In determining the phase center of LPDA antenna we adopt the average shift of phase center to improve the AF. The numerical simulation results show that such an arrangement can result in improvement. We also use the method of PCPM (Phase Center and Pattern Matching) to modify the AF under different conditions of measurement when a ground plane is present. Our study, by using the numerical simulation and measurement, shows that this indeed improves the variation of AF over that obtained by SSM. In addition, efforts are also made to have a detailed discussion in mutually coupling effects between the LPDA antenna and the ground plane, in order to distinguish the impact on AF due to the coupling of the LPDA antenna and its image. Our numerical simulation results indicate that it does not have a significant effect.

In recent high-speed digital circuits with pico-second rising/falling edges, it is reasonable to consider the power/ground planes as a dynamic electromagnetic system. The simultaneous switching noise (SSN) or ground bounce noise (GBN), resulting from the transient currents which flow between power/ground planes during the state transitions of the logic gates, has become a critical factor to degrade the signal integrity (SI) and power integrity (PI) in PCB or package design. In order to accurately perform overall system-level power integrity simulation, extracting the SPICE-compatible models with the resonant effect being considered in the power/ground planes and incorporating the model into the conventional circuit simulator, such as SPICE, is essential. In this thesis, a two-dimensional transmission line (2D-TL) model is proposed for constructing the SPICE-compatible model of the power/ground planes. Based on this model, the ground bounce noise for the BGA package mounted on a PCB can be efficiently evaluated. It is found that the behavior of GBN between the only package and package mounted on a PCB (hybrid structure) is obvious different. Then, we combine the SPICE-compatible model of the power/ground planes with decoupling capacitors to fast evaluate the behavior of GBN. It also has a good agreement between our model and the measured result. Adding decoupling capacitors between the power and ground planes is a typical way to suppress the GBN. However, they are not effective at the frequency higher than GHz due to their inherent lead inductance. In recent, a new method for eliminating the GBN at higher frequency is proposed by electromagnetic bandgap (EBG) structure with high impedance surface (HIS). Finally, we utilize 2D-TL model to fast analyze the behavior of the EBG, and combine decoupling capacitors with EBG structure to research the suppression of the GBN.

Estimation of the ground motion parameters is extremely important for engineers to make the structures safer and more economical, so it is one of the main issues of Earthquake Engineering. Peak values of the ground motions obtained either from existing records or with the help of attenuation relationships, have been used as a useful parameter to estimate the effect of an earthquake on a specific location. Peak Ground Velocities (PGV) of a ground motion is used extensively in the recent years as a measure of intensity and as the primary source of energy-related analysis of structures. Consequently, PGV values are used to construct emergency response systems like Shake Maps or to determine the deformation demands of structures. Despite the importance of the earthquakes for Turkey, there is a lack of suitable attenuation relationships for velocity developed specifically for the country. The aim of this study is to address this deficiency by developing an attenuation relationship for the Peak Ground Velocities of the chosen database based on the strong ground motion records of Turkey. A database is processed with the established techniques and corrected database for the chosen ground motions is formed. Five different forms of equations that were used in the previous studies are selected to be used as models and by using nonlinear regression analysis, best fitted mathematical relation for attenuation is obtained. The result of this study can be used as an effective tool for seismic hazard assessment studies for Turkey. Besides, being a by-product of this study, a corrected database of strong ground motion recordings of Turkey may prone to be a valuable source for the future researchers.

A comprehensive study has been carried out to investigate the correlation between deformation demands of frame structures and a number of widely cited ground motion intensity parameters. Nonlinear response history analyses of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) models derived from sixteen reinforced concrete frames were carried out under a set of eighty ground motion records. The frames were selected to portray features of typical low-to-mid rise reinforced concrete structures. The records contained in the ground motion database were compiled from the recorded ground motions with the intention to possess a broad range of amplitude, frequency content and duration characteristics that shift selected frames into various degrees of elastic as well as inelastic response. Maximum deformation demands of SDOF models and the maximum interstory drift ratios of MDOF models, response parameters of interest, were computed employing 1280 nonlinear response history analyses. Computed response parameters were compared with the ground motion intensity parameters employed and correlation between them were quantified through coefficients of correlation and determination. The results revealed that the spectral intensity parameters including spectral amplitudes over a range of period covering the frame structures have the strongest correlation and present better relationship with the deformation demands compared to the intensity parameters that are based on a single amplitude such as PGA, PGV and spectral acceleration. Besides analytical study, association of ground motion parameters with observed damage has been investigated and no clear trend has been observed between the performance of the buildings and the seismic indices.

Ground-borne vibration from underground rail vehicles is studied analytically. A previously developed model by J.A.Forrest and H.E.M.Hunt is modified to account for different track and vehicle models. The tunnel is modeled as infinite cylindrical shell surrounded by viscoelastic soil. The track is coupled to the tunnel with supports of complex stiffness. The rails, which are modeled as infinite Euler beams, are supported by discrete sleepers with regular spacing, and railpads with complex stiffness. A modified hysteretic damping model for moving loads is applied to soil. Linearized Hertzian contact spring is included between the wheel and the rail. The solution is obtained in frequency domain using random process theory. Effects of improvements in the model are graphically presented to enable comparison with the previously developed model and measurements from literature.

This thesis presents a critical reading of the multilayeredness in contemporary cities through the case of Divanyolu, main road of the historical istanbul. The ground in this case displays the fragmented character, so in order to follow the discontinuities in the morphological, economical, cultural and also hypothetic structures / this study will concentrate on the confrontation of layers within the framework of modernization process in the city. Beyond many possible discussions questioning the multiplicity of Istanbul, this study aims to encompass the specific character of the modernization process observed in Divanyolu. Furthermore, the information derived from the evaluation can suggest an exemplary framework for the new grounds in the multilayered sites, which is actually the other aim of the study. Within this framework, Divanyolu is chosen as a major urban case to discuss the complexity of the stratified ground. It was an example of a stratified ground being the main thoroughfare of the Ottoman Capital, which formed the important network from the Topkapi Palace to the Edirne Gate. The road has been the stage for the modernization process beginning from the 19th century to the present. With the different stage modernization process, the ground displayed the fragmented character. In this thesis, the main dynamics of this partial transformation will be evaluated.

Concentrations of 17 organochlorine and 14 organophosphorus pesticides were measured in 27 ground and 11 surface water samples collected from a heavily agricultural area, Kumluca, in spring and fall seasons of 2005. The samples were preconcentrated by Solid Phase Extraction. GC-ECD and GC-NPD systems were used for quantitative determination of organochlorine and organophosphorus pesticides respectively. The quality check/quality assurance tests were performed by the analysis of field and laboratory blanks, standard reference materials, spiked control and sample matrices, surrogate standards, sampling and analysis replicates. It is observed that, sample matrix lowers average percent recoveries from 89% to 76%. The uncertainties of measurements were calculated to determine major factors affecting the analysis results. It was observed that uncertainty arising from extraction procedure was generally the highest. The most commonly observed pesticide was endosulfan (70%) and chlorpyriphos (53%) for organophosphorus and organochlorine pesticides. The highest average concentration was observed for heptachlor (26 ng/L) and fenamiphos (184 ng/L). Generally pesticides were detected more often in surface waters, where the concentrations were also higher. The concentrations of organophosphorus pesticides in spring, and organochlorine pesticides in fall season were higher. The high occurrences and detection of degradation products of chlorinated pesticides clearly indicate their intense use before 1980s. It is shown that, in Kumluca environment, degradation of these pesticides mostly occurs in surface waters. It is observed that agricultural activities affect water quality in the region. The total concentration limit (500ng/L) was exceeded for 27% of surface and 14% of ground water samples, at least once in both seasons. The legal limit for a single pesticide (100ng/L) was exceeded by 32 % of surface, 24 % of ground water samples.