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<p>In this thesis, we investigate the properties of a model of an anti-phase modulated d-wave superconductor, particularly in the presence of a magnetic field. This so-called model of $\pi$-striped superconductor has been proposed to describe the decoupling between Cu-O planes in $1/8$ doped La$_{2-x}$Ba$_{x}$CuO$_{4}$. The d-wave superconducting order parameter in a $\pi$-striped superconductor oscillates spatially with period 8 and zero average value. Unlike a uniform d-wave superconductor, this model has non-zero density of states at zero energy and exhibits an extended Fermi surface. Within Bogoliubov-de Gennes theory, we study the mixed state of this model and compare it to the case of a uniform d-wave superconductor. We find a periodic structure of the low-energy density of states, with a period that is proportional to $B$, corresponding to Landau levels that are a coherent mixture of particles and holes. These results are also discussed in the context of experiments which observe quantum oscillations in the cuprates.</p> <p>Furthermore, within Bogoliubov-de Gennes theory, a semiclassical approximation is used to study quantum oscillations and to determine the Fermi surface area associated with these oscillations in this model. The Fermi surface is reconstructed via Andreev-Bragg scattering, and the semiclassical motion is along these Fermi surface sections as well as between them via magnetic breakdown. Oscillations periodic in 1/B are found in both the positions and widths of the lowest Landau levels. The area corresponding to these quantum oscillations for intermediate pairing interaction is similar to that reported for experimental measurements in the cuprates. A comparison is made of this theory to data for quantum oscillations in the specific heat measured by Riggs et al.</p> / Doctor of Philosophy (PhD)

Innovative methods to control the viscosity and turbulence in the flow of liquid suspension can be engineered by way of incorporating the concepts of electric and magnetic field into the rheology of complex fluids. Rheology of liquid Chocolate is a very crucial factor in determining the cost of manufacturing process as well as formulating varieties of end consumer products, for example, containing less fat. We have invented a method to lower the viscosity of liquid chocolate flow with the application of electric field. In the lab, we have found that viscosity of chocolate samples is reduced by 40~50% with our method. Thus, fat content in those samples can be reduced by 10% or more. Therefore, we expect to see much healthier and tastier chocolate product in the market once this technology gets implemented in commercial manufacturing. High viscosity and turbulence in blood flow greatly increase the risk of cardiac diseases. Hence, discovering new method to address turbulence suppression and viscosity reduction is critically important. In our study, we have found that in the in-vitro experiment, if blood is subjected to flow through a channel placed inside a strong magnetic field, its viscosity reduces by 10~20%. Based on these findings, a Megneto-Rheology (MR) therapeutic device has been developed to examine the effect on the blood pressure in human subjects. Preliminary clinical trials show that application of this MR therapy reduces blood pressure by 10% or more. In this thesis, above mentioned inventions for the flow of Blood and liquid Chocolate will be thoroughly discussed. / Physics / Accompanied by two .mpeg4 files.

Over the past 20 years research into miniature actuators has been increasing. In addition to having a compact geometry, desirable characteristics for miniature actuators include having a large power-to-weight ratio, fast response, fine resolution of movement and high power efficiency. In the first part of this thesis the design of a miniature rotary robot joint is presented. Two single acting miniature cylinders each with a bore diameter of 4 mm drive the joint using water as the hydraulic fluid. The cylinders are mated to a rack and pinion mechanism that converts the opposing linear motion of the cylinders shafts into rotation. Also within the design, a novel position sensor using magnetic field sensing technology is presented. Overall, the joint measures 11 mm wide x 8.8 mm high x 150 mm long. In the second part of this thesis a hydraulic servo positioning system is presented along with a novel valve modeling technique and two position control strategies. Four low-cost, 3-way on/off solenoid valves were used to control the flow of the water in and out of the cylinders. The two nonlinear position controllers employed were a position-velocity-acceleration plus model-based feedforward controller (PVA+FF) and a novel PVA + FF plus sliding mode controller. For experiments involving horizontal rotation of the joint while carrying no load the PVA +FF controller achieved a steady-state error of ± 0.77° or ± 0.06 mm in terms of rack position. The steady-state error produced by the PVA + FF plus sliding mode controller was ± 0.85° or ± 0.07 mm. The maximum tracking error produced by both controllers was 5° or 0.41 mm and occurred during the initial cycloidal rising portion of a 120° displacement. The root mean square error (RMSE) of the PVA + FF and PVA + FF plus sliding mode controllers were 42% and 54% less than that produced by a linear PVA controller. Both controllers were found to be robust to changes in payload. This was experimentally verified by adding masses of 6.5 g and 13.5 g to the end of the output link of the joint. By conducting similar experiments in the vertical direction it was found that the PVA + FF plus sliding mode controller was more robust, achieving on average a 30% reduction in RMSE compared to the FF + PVA controller. / Thesis / Master of Applied Science (MASc)

The experimental investigations of Sn diffusion in ferromagnetic α-Fe within the pulsed magnetic field by X-ray diffraction analysis were performed. The pulsed magnetic field was found to influence significantly the diffusion coefficients of Sn in α-Fe.

In the report the results of phase formation and magnetoplastic effect (МPE) researches in five alloys on the Al-basis with additives Mg, Li, Zn, Cu, Si, Fe and Mn, aged in a constant magnetic field (CMF) and pulse magnetic field (PMF), are presented. Preliminary the samples subjected to annealing in the furnace at the air atmosphere, then quenched in water at a room temperature. Further the quenched samples are artificial aged in vacuum in CMF and PMF and without it. Microstructure, MPE, phase content and parameters of thin structure of a residual α-matrix of samples have been investigated by methods of metallography, microhardness, X-ray structure and phase analysis.

Layer-by-layer (LBL) polyelectrolyte capsules can be modified to incorporate stimuli such as superparamagnetic nanoparticles which respond to a magnetic field only when it is turned on. Thus, they can act as a switch to load or unload their drug cargo on demand. Specifically, magnetite is incorporated into bilayer capsules made of alternating poly(allylamine hydrochloride) (PAH) and poly(sodium-p-styrenesulfonate) (PSS) which surrounds calcium carbonate core. The core is then dissolved using ethylenediaminetetraacetic acid (EDTA). These capsules are loaded with at FITC-BSA conjugate and examined with fluorescence to show the unloading of the FITC-BSA from capsules as it brightens the entire field of view of the microscope. The results suggest that we can next load and unload an anticancer drug such as doxorubicin using the combination of microcapsule and alternating magnetic field (AMF) to treat the cancer cells. Preliminary data interprets that the low frequency AMF we use has little to no adverse effect cells viability. This coincides with the general thought that low frequency AMF signals are not harmful to humans. Therefore, as an alternative to hyperthermia methods which use heat, it may be possible to deliver the anticancer drugs specifically to the cells when and where it is needed.

Master of Science / We are in an ever-increasing demand for computing power to sustain our technological advancements. A significant driving factor of our progress is the size and speed of memory we possess. Modern computer architectures use DDR4-based DRAM (Dynamic Random Access Memory) to hold all the immediate information for processing needs. Each bit in a DRAM memory module is implemented with a tiny capacitor and a transistor. Since the capacitors are prone to charge leakage, each bit must be frequently rewritten with its old value. A dedicated memory controller handles the periodic refreshes. If the cells aren't refreshed, the bits lose their charge and lose the information stored by flipping to either 0 or 1 (depending upon the design). Due to manufacturing variations, every tiny capacitor fabricated will have different physical characteristics. Charge leakage depends upon capacitance and other such physical properties. Hence, no two DRAM modules can have the same properties and decay pattern and cannot be reproduced again accurately. This DRAM attribute can be considered a source of 'Physically Unclonable Functions' and is sought after in the Cryptography domain. This thesis aims to characterize the decay patterns of commercial DDR4 DRAM modules. I implemented a custom System On Chip on AMD/Xilinx's ZCU104 FPGA platform to interface different DDR4 modules with a primitive memory controller (without refreshes). Additionally, I introduced electric and magnetic fields close to the DRAM module to investigate their effects on the decay characteristics.