As a racecar negotiates a track, it is subjected to many inputs at both high and low frequencies. These inputs come from the track surface, the motion of the body, and from aerodynamic disturbances. The damper's ability to control these inputs leads to improved grip at the tires, which increases overall handling of the vehicle. Since dampers have always been assumed to be primarily velocity dependent, little work has gone into exploring damper's frequency dependent nature. Therefore, this study evaluates the effect input frequency has on the damper's output force. Utilizing experimental testing, with a state of the art damper dynamometer, and computer simulation with a parametric damper model developed for this study, several inputs and key parameters are tested, and the damper's frequency dependent nature starts to emerge. Constant peak velocity sinusoidal and sinusoidal sweep inputs are used for the experimental testing. The results show that as the input frequency is increased, the damper's output force lissajou transitions from the characteristic shape of a damper's lissajou to a shape characteristic of a spring's lissajou. This change in the lissajou is linked to hysteretic effects, which includes the gas spring effect. Damper parameters that are suspected to contribute to the hysteretic effects are explored with computer simulation and additional experimental testing. The results from this show that fluid preparation, fluid type, initial gas pressure, and friction have a predictable effect on the damper's output force. / Master of Science

Magnetorheolgical (MR) fluid dampers have the capability of changing their effective damping force depending on the current input to the damper. A number of factors in the construction of the damper, as well as the properties of the fluid and the electromagnet, create a dynamic response of the damper that cannot be fully described with a static model dependent on current and velocity. This study will compare different techniques for modeling the force response of the damper in the current-velocity space. To ensure that all the dynamic response characteristics of the damper are captured in data collection, random input signals were used for velocity and current inputs. By providing a normally distributed random signal for velocity to a shock dynamometer and a uniformly distributed random signal for current to a Lord rheonetic seat damper, the force response could be measured. The data from this test is analyzed as a two dimensional signal, a three dimensional force plot in the current velocity plane, and as a probability density function. Four models are created to fit the data. The first is a linear model dependent solely on current. The second is a nonlinear model dependent on both current and velocity. The third model takes the nonlinear model and includes a filter that affects the force response of the model with time. Each of these three approaches are compared based on the total error in the force response and the models? ability to match the PDF of the data. Finally, a fourth model is created for the damper that improves the nonlinear model by making one parameter a probability parameter defined by a PDF calculated from the data. However, because it is a probability model, the error cannot be found through comparison to the data. / Master of Science

Silicon carbide (SiC) is a wide bandgap material capable of higher voltage and higher temperature operation compared to its silicon (Si) counterparts due to its higher critical electric field (E-field) and higher thermal conductivity. Using SiC, MOSFETs with a theoretical high temperature operation and reliability is achievable. However, current bottlenecks in high temperature SiC MOSFETs lie within the limitations of standard packaging. Additionally, there are reliability issues relating to the gate oxide region of the MOSFET, which is exacerbated through high temperature conditions. In this thesis, high temperature effects on current-generation SiC MOSFETs are studied and analyzed. To achieve this, a high temperature package is created to achieve reliable operation of a SiC MOSFET at junction temperatures of 300 °C. The custom, high temperature package feasibility is verified through studying trends in SiC MOSFET behavior with increasing temperature up to 300 °C by static characterization. Additionally, the reliability of SiC MOSFETs at 300 °C is tested with accelerated lifetime bias tests. / M.S. / Electrical devices that are rated for high temperature applications demand a use of a material that is stable and reliable at the elevated temperatures. Silicon carbide (SiC) is such a material. Devices made from SiC are able to switch faster, have a superior efficiency, and are capable of operating at extreme temperatures much better than the currently widely used silicon (Si) devices. There are limitations on SiC certain structures of SiC devices, such as the metal oxide semiconductor field effect transistor (MOSFET), have inherent reliability issues related to the fabrication of the device. These reliability issues can get worse over higher temperature ranges. Therefore, studies must be made to determine the feasibility of SiC MOSFETs in high temperature applications. To do so, industry standard tests are conducted on newer generation SiC MOSFETs to ascertain their use for said conditions.

The development of label-free optical biosensors is motivated by the need for highly accurate and sensitive measurements of biomolecular interactions. The Interferometric Reflectance Imaging Sensor (IRIS) delivers precise and multiplexed detection of such interactions. A significant challenge in label-free sensing is the bulk effect, which is the presence of unwanted signals caused by variations in refractive index that can obscure true binding interactions and lead to inaccurate measurements. This thesis presents multiple advancements to IRIS technology focusing on the quantitative detection and elimination of the bulk effect using the principles of light reflection in different colors. A novel bulk-effect-free signal calculation method is introduced, significantly reducing sensitivity to refractive index variations. Additionally, a methodology for real-time detection of changes in refractive index is developed. Both systems are theoretically validated through MATLAB simulations. Experiments were conducted to demonstrate the effectiveness of the bulk-effect- free signal measurement and the refractive index detection system. Two main types of experiments were performed: with solutions of varying refractive indices without actual binding to detect refractive index changes and binding experiments to test new systems' effectiveness in detecting true biomolecular interactions. Novel experimental procedures using a combination of these methods were introduced to eliminate the bulk effect. This thesis establishes the foundation for the next-generation multicolor IRIS system, enhancing its potential for accurately detecting biomolecular interactions by eliminating the bulk effect and incorporating refractive index detection. / 2026-09-10T00:00:00Z

Tuberculosis, caused by Mycobacterium tuberculosis (MTB), is a common and potentially lethal infectious human disease. Rifampicin is a front line anti-tuberculosis drug usually prescribed in combination with isoniazid, pyrazinamide and streptomycin for a period of six to seven months. When given orally for the treatment of MTB, rifampicin exhibits low bioavailability. Recent attempts to increase bioavailability and decrease dosage of anti-tuberculosis drugs have focused on creating polymer coated rifampicin nanoparticles. The research effort presented in this thesis evaluates the formation, characterization and relative bioavailability of rifampicin loaded carboxymethylcellulose acetate butyrate (CMCAB) particles using two different formulation techniques. Multi inlet vortex mixer (MIVM) and manual spray drying techniques were used to form the rifampicin containing CMCAB particles. Characterization studies and analyses of particles revealed differences in particle sizes, shapes and drug loading between the different particle formulation techniques. In vivo pharmacokinetic studies in BALB/c mice indicate that a single dose of rifampicin laden CMCAB spray dried particle formulations are able to improve pharmacokinetic parameters including relative bioavailability of rifampicin compared to that of the free drug form at the same concentration. / Master of Science

Ionomeric polymer transducers (IPTs) are an exciting new class of smart materials that can serve a dual purpose in engineering or biomedical applications as sensors or actuators. Most commonly they are used for mechanical actuation, as they have the ability to generate large bending strains and moderate stress under low applied voltages. Although the actuation capabilities of IPTs have been extensively studied, the sensing capabilities of these transducers have yet to be fully explored. The work presented herein aims to investigate the fundamental sensing characteristics of these transducers and apply the acquired knowledge toward the development of an electronic stethoscope for digital auscultation. The sensors were characterized both geometrically and electrically to determine their effectiveness in resolving a signal from sub 1 Hz to 2 kHz. Impedance spectroscopy was used to interrogate the sensing mechanism. Following the characterization of the transducer, a bio–acoustic sensor was designed and fabricated. The bio–acoustic sensor was placed over the carotid artery to resolve the arterial pressure waveform in situ and on the thorax to measure the S1 and S2 sounds generated by the heart. The temporal response and spectral content was compared with previously known data and a commercially available electronic stethoscope to prove the acquisition of cardiovascular sounds. / Master of Science

Water treatment facilities commonly reduce soluble contaminants, such as soluble manganese (Mn2+), in water by oxidation and subsequent filtration. Previous studies have shown that conventional porous filter system removes Mn2+ from drinking water by developing Mn-oxides (MnOx(s)) bearing coating layers on the surface of filter media. Multiple models have been developed to explain this Mn2+ removal process and the formation mechanism of MnOx(s) coatings. Both, experimental and theoretical studies to date have been largely focused on the micrometer to millimeter scale range; whereas, coating layers are composed of nanoscale particles and films. Hence, understanding the nanoscale particle and film formation mechanisms is essential to comprehend the complexity of soluble contaminant removal processes. The primary objective of this study was to understand the initial MnOx(s) coating formation mechanisms and evaluate the influence of filter media characteristics on these processes. We pursued this objective by characterizing at the micro and nanoscale MnOx(s) coatings developed on different filter media by bench-scale column tests with simulating inorganic aqueous chemistry of a typical coagulation fresh water treatment plant, where free chlorine is present across filter bed. Analytical SEM and TEM, powder and synchrotron-based XRD, XPS, and ICPMS were used for characterization of coatings, filter media and water solution elemental chemistry. A secondary objective was to model how surface coating formation occurred and its correlation with experimentally observed physical characteristics. This modeling exercise indicates that surface roughness and morphology of filtering media are the major contributing factors in surface coating formation process. Contrary to previous models that assumed a uniform distribution and growth of surface coating, the experimental results showed that greater amounts of coating were developed in rougher areas. At the very early stage of coating formation, unevenly distributed thin films and/or particle aggregates were observed, which provided active sites for further surface coating growth. The predominant MnOx(s) phase in the surface coatings was identified to be poorly crystalline birnessite having scavenging activity by intercalation and/or sorption. This would explain the enhancement of efficiency in removing soluble manganese and other contaminants during water filtration. Moreover, the increased Mn2+ removal effect of having aluminum (Al) in pre-treated water is explained. These results indicate that the surface roughness and morphology need to be incorporated into particle capture models to more precisely describe the soluble manganese removal process. / Ph. D.

Knowledge of water distribution in sludges is important in developing a better understanding of the mechanisms by which various fractions of water are bound to the sludge matrix as well as the extent to which sludges may be dewatered in an economic manner. Various models have been proposed in the literature to describe the types or fractions of water present in sludges, both before and after dewatering. Likewise, there exist a variety of measurement techniques to quantify the fractions of water believed to be present in sludges. The major objective of the research reported herein was an attempt to develop a more rational basis for defining the various fractions of water present in sludges, as well as to apply and develop feasible analytical techniques to characterize moisture distribution in sludges and determine if there was any correlation between these techniques. Secondary objectives included investigation of polymer addition, mechanical dewatering, and the effect of freeze-thaw cycles to different water fractions in sludge samples, and measuring or estimating various densities (bulk, floc, dry) and specific surface areas of sludge particles in an attempt to predict the dewatering performance of various sludge samples. The matrix of sludges included various water treatment plant/inorganic chemical sludges and biosolids. The sludge moisture characterization techniques used or developed in this study were the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dilatometric methods. The TGA method developed used the drying curve rate technique whereby changes in the drying (water removal) rates would provide information on moisture distribution in sludges. The DSC and dilatometric methods used the property of the free water fraction to freeze by -20° C, as compared to the bound water fraction that is thought not to freeze until well below -20°C. It was found that there were uncertainties in the determination of different sub-fractions of sludge water. In an effort to better rationalize these various subfractions, it has been proposed in this study that water in sludges be considered to be in two major fractions: bound and unbound. For the TGA, the demarcation point between these two fractions was indicated by the onset of the first critical/inflection point on the drying rate curve. The DSC and dilatometric methods determined the amount of bound water by first measuring the amount of unbound water that froze by -20°C, and subtracting this value from the total water present in the dry solids analysis. While the DSC measured the calorimetric (enthalpic) changes, the dilatometer measured the expansion of the unbound water. The three DSC instruments evaluated in this study were not able to measure the rapid exothermic change of the freezing of unbound water, but was able to measure the amount of unbound water that melted. Freezing point depression (supercooling) phenomena was also observed for various samples using this technique. Due to these effects, the sludge moisture characterization method developed for the DSC measured the amount of unbound water from the endothermic changes upon melting. The three different analytical techniques used to determine moisture in sludges were found to provide different quantities of the bound water fraction. Other sludge characteristics evaluated included the bulk, floc, and dry density values, as well as the specific surface area of dry sludge particles. Correlations were attempted to determine if there were any meaningful relationships in the results obtained. / Ph. D.

Pelvic organ prolapse, the decent of the pelvic organs from their normal anatomical position, is a common condition among women that is associated with mechanical alterations of the vaginal wall. In order to characterize the complex mechanical behavior of the vagina, we performed planar biaxial tests of vaginal specimens in both the passive (relaxed) and active (contracted) states. Specimens were isolated from virgin, female Long-Evans rats (n=16) and simultaneously stretched along the longitudinal direction (LD) and circumferential direction (CD) of the vagina. Tissue contraction was induced by electric field stimulation (EFS) at incrementally increasing values of stretch and, subsequently, by KCl. On average, the vagina was stiffer in the CD than in the LD (p<0.001). The mean maximum EFS-induced active stress was significantly higher in the CD than in the LD (p<0.001). On the contrary, the mean KCl-induced active stress was lower in the CD than in the LD (p<0.01). When comparing the mean maximum EFS-induced active stress to the mean KCl-induced active stress, no differences were found in the CD (p=0.404) but, in the LD, the mean active stress was much higher in response to the KCl stimulation (p<0.001). Collectively, these results demonstrate that the anisotropic behavior of the vaginal tissue is determined not only by the collagen and smooth muscle fiber organization but also by the innervation. The findings of this study may contribute to the development of more effective treatments for pelvic organ prolapse. / MS / Pelvic organ prolapse (POP), the decent of the pelvic organs from their normal anatomical position, is a common condition among women that is associated with alterations of the mechanical properties of the vaginal wall. The characterization of the mechanical properties of the vagina is crucial for the development of effective treatments for POP. Biaxial tensile tests were performed in this study so we could observe the behavior of the vagina along both the circumferential direction (CD) and the longitudinal direction (LD). In these tests, square specimens were secured along all four edges and pulled outward such that we could observe the relationship between the stretch and the stress that the tissue experienced. Additionally, because the vagina contains smooth muscle, we also tested the tissue in its active, or contractile state at each stretch level. Contractions were induced by applying electric field stimulation (EFS) to observe nerve-mediated responses, and subsequently by potassium chloride (KCl). On average, the vagina was stiffer in the CD than in the LD (p<0.001). The mean maximum EFS-induced active stress was significantly higher in the CD than in the LD (p<0.001). On the contrary, the mean KCl-induced active stress was lower in the CD than in the LD (p<0.01).

The Thrace Basin, NW Turkey, is one of the most important basins in Turkey in terms of hydrocarbon potential. Previous studies, starting in the 1930s, focused on tectonics, basin evolution, sedimentation and stratigraphy, depositional systems, and hydrocarbon potential. Eocene turbiditic sandstones and reefal limestones, and Oligocene deltaic sandstones are the major reservoir targets in the basin today. The focus of this research is the Upper Oligocene deltaic sandstones, namely the Danismen and Osmancik formations, which contain potential hydrocarbon reservoirs. The aims of research were to develop a better understanding of the geometric configuration of the Oligocene strata and to identify potential reservoirs within the study area. Accordingly, the geometric configurations of the strata were delineated using 3D seismic reflection data whereas petro-physical properties of the target formations were determined using wireline logs from three wells. A right-lateral strike slip or reverse fault system and associated NW-SE trending asymmetric fold extend across the study area. Both the fault system and the fold are truncated beneath the Miocene unconformity and are thus dated as late Oligocene to early Miocene in age. The Miocene unconformity forms a stratigraphic trap whereas the fault system and associated fold construct a NW-SE trending structural trap. Hydrocarbon-bearing, five main clean sandstone (shale volume less than %10) intervals were identified using wireline logs and evaluated as potential targets. Hydrocarbon concentrations increase through the fold structure. Thus, the fault system and the associated asymmetric fold were the main factors that affected the zonal distribution of hydrocarbons in the study area. / Master of Science / Thrace Basin, northwest part of Turkey, is one of the most important basins in Turkey in terms of oil and gas potential. Previous studies started in1930s and included studies on the geology of the basin. Major reservoir targets in the basin today are Eocene turbiditic sandstones and reefal limestones, and Oligocene deltaic sandstones. This study focuses on the Oligocene deltaic sandstones of the Danismen and Osmancik formations, which are significant in terms of the oil and gas potential in the basin. The main purpose of this thesis is to evaluate the geometric configurations of these two formations and to identify potential reservoirs within the study area. For this purpose, geometric representation of the study area was generated by mapping the formations with the help of 3D seismic data. Reservoir characteristics related to physical properties were determined by utilizing the data obtained from three wells within the study area. As a result, potential reservoir zones are discovered mainly in the Danismen Formation, which can further be incorporated with exploration activities in the basin.