Redesigning heavy components with thinner components is one way to lower automotive weight and improve fuel efficiency. Therefore, replacing thick cast iron exhaust manifolds with thinner heat resistant stainless steel one is a prime example of this approach. Material for a thin exhaust manifold must tolerate cyclic thermal fatigue. In SUS 444, this characteristic is directly related to the influence of microstructure on high temperature strength and the stability of the microstructure at the high operating temperature range. The goal of this research is to identify the cause for the drastic difference in the stress-strain behavior between two potential manufacturer heat treatments that will serve as a simplified model case for high temperature cyclic fatigue.  Transmission electron microscopy (TEM) based microstructure analyses of samples which have been aged at 750"C for 100 hours and then hot-tensile tested at 750"C with a strain rate of   suggest continuous recrystallization as the mechanism responsible for the stable high temperature strength. The initial high temperature strength observed in the unaged sample was due to the precipitation of fine Laves phases which pinned down the motion of dislocations. As deformation progressed the strength increased until a critical precipitate size, volume fraction and dislocation density before Laves phases begun to rapidly coarsen and resulted in the abrupt decrease in strength. Microstructure evidence suggests the absence of precipitation strengthening effect in the aged samples could be a contributing factor to the decrease in peak strength between the aged samples and the unaged samples. / Master of Science

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Context: Clinicians use a number of superficial and deep heating modalities, including pulsed shortwave diathermy (PSWD) and moist hot packs, in the clinical setting. Recently, a continuous diathermy unit called ReBound was introduced into the clinical setting. Its effectiveness as a heating modality is unknown. Objective: To compare the effects of PSWD, moist hot packs and the ReBound unit on tissue temperature in the triceps surae muscle. Design: A 3 x 27 factorial cross-over design with repeated measures. Setting: University research laboratory. Subjects: Twelve healthy college-aged volunteers (4 men, 8 women; age = 22.2 ± 2.25; calf subcutaneous fat thickness = .72 cm ± .19 cm). Interventions: On three different days separated by at least 48 hours, one of three modality treatments (PSWD, moist hot packs or ReBound unit) selected using a Latin-square was applied to the triceps surae muscle of each participant for 30 minutes. After the 30 minute treatment, the modality was removed and temperature decay was recorded for 20 minutes. Main Outcome Measures: Medial triceps surae intramuscular tissue temperature at 1 cm and 3 cm deep was measured using implantable thermocouples inserted horizontally into the muscle. Measurements were taken every 5 minutes during the 30 minute treatment and every minute during the 20 minute temperature decay for a total of 50 minutes. A 3 x 27 mixed model analysis of variance blocking by subject was used to assess the effects of treatments and time, and their interaction on the tissue temperature at 1 cm and 3 cm depths. Results: A significant treatment by time interaction main effect was found for tissue temperature increase at each depth, 1 cm (F52, 572 =14.66, p < .0001) and 3 cm (F52, 572 = 17.86, p < .0001). Post-hoc measures revealed that tissue temperature significantly increased with the PSWD over the ReBound unit and moist hot packs at 1 cm and 3 cm depths. There was no significant difference between the ReBound unit and moist hot packs throughout the treatment and temperature decay. The greatest mean tissue temperature increase from baseline was observed with the PSWD unit at 1 cm (5.96°C ± 2.04°C) and at 3 cm (4.32°C ± 1.79°C). There was no statistical difference between the increases observed with the ReBound (1 cm: 3.69°C ± 1.50; 3 cm: 2.31°C ± .87) and moist hot packs (1 cm: 2.82°C ± .90; 3 cm: 1.56°C ± 1.00). Conclusions: During a 30 minute treatment, PSWD was the most effective at increasing intramuscular tissue temperature of the triceps surae muscle group. There was no significant difference between the effectiveness of moist hot packs and the ReBound continuous diathermy unit in increasing intramuscular tissue temperature.

Purpose: An experimental study to examine the effects of CardioWaves interval training (IT) and continuous training (CT) on resting blood pressure, resting heart rate, and mind-body wellness. Methods: Fifty-two normotensive (blood pressure <120/80 mmHg), pre-hypertensive (120-139/80-89 mmHg), and hypertensive (>140/90 mmHg) participants were randomly assigned and equally divided between the IT and CT groups. Both groups participated in the assigned exercise protocol thirty minutes per day, four days per week for eight weeks. Resting blood pressure, resting heart rate, and mind-body wellness were measured pre- and post-intervention. Results: A total of 47 participants (15 females and 32 males) were included in the analysis. The IT group had a non-significant trend of reduced systolic blood pressure (SBP) and increased diastolic blood pressure (DBP) while the CT group had a statistically significant decrease in awake SBP (p=0.01) and total SBP (p=0.01) and a non-significant decrease in DBP. With both groups combined, the female participants had a statistically significant decrease in awake SBP (p=0.002), asleep SBP (p=0.01), total SBP (p=0.003), awake DBP (p=0.02), and total DBP (p=0.05). The male participants had an increase in SBP and DBP with total DBP showing a statistically significant increase (p=0.05). Neither group had consistent change in resting heart rate. Both groups showed improved mind-body wellness. Conclusion: IT and CT reduced resting blood pressure, with CT having a greater effect. Resting heart rate did not change in either group. Additionally, both IT and CT improved mind-body wellness.

DevOps and continuous practices are increasingly popular development practices aiming at bridging the gap between software development and IT operations with the indented outcome of shorter development life cycles while maintaining a high software quality. A fundamental part of many DevOps systems is a CI/CD (continuous integration/deployment) pipeline allowing for automatic building, testing and deployment of software. The use of continuous practices have been shown to achieve the desired outcomes, whereas the adopting of such practices has been attributed with the challenges of lacking expertise and skill as well as lacking available tools and technology. Execution of commands in a CI/CD pipeline are handled by a runner application, which can be configured in different ways allowing for different levels of the quality attributes performance, response time, throughput, robustness, stability, resource constraints, cost and maintainability. Five different types of runner infrastructure were implemented and evaluated on the quality attributes. These were: one single-machine implementation, one serverless implementation and three autoscaling implementations. For robustness and stability autoscaling implementations achieved the best results. Performance and throughput were affected by resource constraints which in turn affected the cost. Similar results were found for response time for all but one of the three autoscaling implementations, and for the serverless implementation. Finally, all implementations had similar results for reliability.

Energy and performance improvements of continuous-time analog-based computation for selected applications offer an avenue to continue improving the computational ability of tomorrow*s electronic devices at current technology scaling limits. However, analog computation is plagued by the difficulty of designing complex computational circuits, programmability, as well as the inherent lack of accuracy and precision when compared to digital implementations. In this thesis, evolutionary algorithm-based techniques are utilized within a reconfigurable analog fabric to realize an automated method of designing analog-based computational circuits while adapting the functional range to improve performance. A Self-Scaling Genetic Algorithm is proposed to adapt solutions to computationally-tractable ranges in hardware-constrained analog reconfigurable fabrics. It operates by utilizing a Particle Swarm Optimization (PSO) algorithm that operates synergistically with a Genetic Algorithm (GA) to adaptively scale and translate the functional range of computational circuits composed of high-level or low-level Computational Analog Elements to improve performance and realize functionality otherwise unobtainable on the intrinsic platform. The technique is demonstrated by evolving square, square-root, cube, and cube-root analog computational circuits on the Cypress PSoC-5LP System-on-Chip. Results indicate that the Self-Scaling Genetic Algorithm improves our error metric on average 7.18-fold, up to 12.92-fold for computational circuits that produce outputs beyond device range. Results were also favorable compared to previous works, which utilized extrinsic evolution of circuits with much greater complexity than was possible on the PSoC-5LP.

A continuous flow, passive separation device was designed using an equivalent circuit to create variable flow rates for hydrodynamic focusing to drain channels and collection outlets. By varying the diameter of the sample inlet connection into the reservoir, the particle position was influenced significantly, which enabled desired separations. Additionally it was noted that the relative, horizontal position of the inlet also had a significant influence on particle position within the device. A dimensionless number, the Characteristic Sample Inlet, was developed to relate geometric properties of the inlet reservoir to downstream particle distribution. It was found that a 2:1 ratio between inlet reservoir and sample inlet diameter, and placed at the top of the reservoir yielded the best separation results. Fluid velocity profiles in the reservoir were explored using Comsol Multyphysics. The experimentally observed particle trajectories and COMSOL predictions were in good agreement. Based on Comsol models a dimensionless parameter to relate the unique velocity profiles within the inlet reservoir to downstream separation of particles was also developed. A mixture of 10, 5.5, and 3.0 µm particles were separated to three distinct collection outlets at 73.4%, 64.7%, and 52.8% respectively. Therefore this project shows that passive separations of particles can be achieved simply by alerting the ratio of inlet hole relative to inlet reservoir diameter, and by placing the inlet hole at the top of the reservoir.

Co-continuous structures generated from the phase separation of polymer blends present many opportunities for practical application. Due to the large interfacial area in such structures and the incompatibility between the components, such non-equilibrium structures tend to coarsen spontaneously into larger sizes and eventually form dispersed morphologies. Here, we utilize various strategies to kinetically stabilize the co-continuous structures in polymer blend systems at nano- to micro- size scales. In the partially miscible blend of polystyrene and poly(vinyl methyl ether), we took advantage of the spinodal decomposition (SD) process upon thermal quenching, and arrested the co-continuous micro-structures by the addition of nanoparticles. In this approach, the critical factor for structural stabilization is that the nanoparticles are preferentially segregated into one phase of a polymer mixture undergoing SD and form a percolated network (colloidal gel) beyond a critical loading of nanoparticles. Once formed, this network prevents further structural coarsening and thus arrests the co-continuous structure with a characteristic length scale of several microns. Our findings indicate that a key to arresting the co-continuous blend morphology at modest volume fractions of preferentially-wetted particles is to have attractive, rather than repulsive, interactions between particles. For the immiscible blend of polystyrene and poly(2-vinyl pyridine) (PS/P2VP), we presented a strategy to compatibilize the blend by using random copolymers of styrene and 2-vinylpyridine, controlling the degree of immiscibility between PS and P2VP. Based on such compatibilization, co-continuous structured membranes, having characteristic size down to tens of nanometers, were fabricated in a facile way, via the solvent-induced macrophase separation of polymer blend thin films. The feature size was controlled by controlling the film thickness and varying the molecular weight of the PS homopolymer and the random copolymers. As the processing method (solution casting) is simple and the structures are insensitive to the solvent or substrate choices, this approach shows great potential in the large scale fabrication of co-continuous nanoscopic templates on flexible substrates via roll-to-roll processes. Moreover, we proposed a quasi-binary blend system based on the PS/P2VP pair with the addition of a common solvent. An experimentally accessible phase mixing temperature was achieved, and the co-continuous morphologies were generated via thermally induced spinodal decomposition. The addition of solid particles significantly slowed down the coarsening kinetics and, in some cases, arrested the co-continuous structures at ~6 &mum for a short period of time. This study suggests an alternative means to achieve co-continuous structures in polymer solutions and also provides better understanding of the thermodynamics and kinetics of polymer blend phase separation. Our research demonstrates several means of kinetically trapping the non-equilibrium interconnected structures at sub-micron to tens-of-nanometer size scales that are germane to several functions including active layers of photovoltaic cells and polymer-based membranes.

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<p> This dissertation describes an investigation into the free radical polymerization of styrene in continuous stirred tank reactors (CSTR's). The aim was to develop a steady state polymerization model which would accurately predict conversion and molecular weight distribution (MWD) up to high conversion. </p> <p> The dissertation is divided into three self-contained parts. Part I describes the testing and development of polymerization kinetics using a single CSTR. The single CSTR model is described. Theoretical and experimental conversions and MWD's are compared and discussed. </p> <p> Part II describes the development of a model for a system of CSTR's. It is based upon the single CSTR model and the kinetics developed in Part I. Theoretical and experimental results for a three reactor system are compared and discussed. </p> <p> Part III describes the development of gel permeation chromatography (GPC) for measuring MWD. Molecular weight and resolution calibration data are presented and discussed. Four methods of chromatogram interpretation that correct for imperfect resolution are compared. </p> / Thesis / Doctor of Philosophy (PhD)