This work describes the modeling, control design, and experimental verification of an electromagnetic suspension system with position feedback using infrared sensors. A nonlinear model is obtained by fitting a first principle analytical model of the system to experimental data. A sliding control strategy is designed using a sliding surface derived from the model to achieve robust stabilization for the closed-loop system. The control is then implemented on an embedded commercial DSP system for experimental verification of the designed control on a laboratory scale electromagnetic suspension system. To compensate for the steady-state tracking error, two modifications are considered. In the first method, a small magnitude integral term is added to the error feedback, equivalently adjusting the reference signal and eliminating the constant bias. In the second method, an integral sliding control is considered, using a higher-order sliding surface, which also eliminates the constant bias. The experimental results show the efficacy of all designed control techniques. The modified techniques, unlike the original design, effectively eliminate the constant position error.

This project explores the fundamental mechanisms of grain boundary sliding (GBS) with an emphasis on its role in superplasticity, using both micro- and macro-mechanical testing methods. GBS plays an important role in the deformation of polycrystalline materials, especially at high homologous temperatures (above half of the melting point). Classical models for GBS (Rachinger sliding and Lifshitz sliding) assume that all grains and grain boundaries undergo the same process, but recent research has shown this is not true. Individual grain boundaries differ in their ability to participate in sliding and diffusion. Therefore, it is important to investigate the response of individual grain boundaries to stress. This project uses microcantilevers, loaded using a nanoindenter, to investigate the response to stress of individual grain boundaries in Sn-1%Bi, which is expected to exhibit GBS at room temperature. The response of individual grain boundaries are correlated with grain boundary characters determined using electron backscattered diffraction (EBSD). On the macroscopic scale, both in-situ and ex-situ shear tests are conducted to investigate the superplastic behaviour of this material. The strain rate sensitivity index of the material with a grain size of 8.5 μm is found to be around 0.45. Surface marker lines have quantitatively revealed grain boundary sliding. The investigation from surface studies is expanded to the interior of bulk material in 3D by conducting an in-situ tensile test coupled with diffraction contrast tomography (DCT) at a synchrotron facility. The microcantilever tests enable grain boundary sliding and diffusion creep to be investigated separately by varying the normal and shear stresses on the grain boundary plane. GBS is dependent on grain boundary structure (misorientation angle, rotation axis and grain boundary plane orientation). The microcantilever size is similar to the grain size used in the macro-mechanical tests. It is demonstrated that the shear stress for steady-state GBS is comparable in micro- and macro-tests. Grain neighbour switching events have been identified in the interior of bulk material in 3D for the first time.

abstract: Solution conformations and dynamics of proteins and protein-DNA complexes are often difficult to predict from their crystal structures. The crystal structure only shows a snapshot of the different conformations these biological molecules can have in solution. Multiple different conformations can exist in solution and potentially have more importance in the biological activity. DNA sliding clamps are a family of proteins with known crystal structures. These clamps encircle the DNA and enable other proteins to interact more efficiently with the DNA. Eukaryotic PCNA and prokaryotic β clamp are two of these clamps, some of the most stable homo-oligomers known. However, their solution stability and conformational equilibrium have not been investigated in depth before. Presented here are the studies involving two sliding clamps: yeast PCNA and bacterial β clamp. These studies show that the β clamp has a very different solution stability than PCNA. These conclusions were reached through various different fluorescence-based experiments, including fluorescence correlation spectroscopy (FCS), Förster resonance energy transfer (FRET), single molecule fluorescence, and various time resolved fluorescence techniques. Interpretations of these, and all other, fluorescence-based experiments are often affected by the properties of the fluorophores employed. Often the fluorescence properties of these fluorophores are influenced by their microenvironments. Fluorophores are known to sometimes interact with biological molecules, and this can have pronounced effects on the rotational mobility and photophysical properties of the dye. Misunderstanding the effect of these photophysical and rotational properties can lead to a misinterpretation of the obtained data. In this thesis, photophysical behaviors of various organic dyes were studied in the presence of deoxymononucleotides to examine more closely how interactions between fluorophores and DNA bases can affect fluorescent properties. Furthermore, the properties of cyanine dyes when bound to DNA and the effect of restricted rotation on FRET are presented in this thesis. This thesis involves studying fluorophore photophysics in various microenvironments and then expanding into the solution stability and dynamics of the DNA sliding clamps. / Dissertation/Thesis / Ph.D. Chemistry 2013

abstract: Sliding-Mode Control (SMC) has several benefits over traditional Proportional-Integral-Differential (PID) control in terms of fast transient response, robustness to parameter and component variations, and low sensitivity to loop disturbances. An All-Digital Sliding-Mode (ADSM) controlled DC-DC converter, utilizing single-bit oversampled frequency domain digitizers is proposed. In the proposed approach, feedback and reference digitizing Analog-to-Digital Converters (ADC) are based on a single-bit, first order Sigma-Delta frequency to digital converter, running at 32MHz over-sampling rate. The ADSM regulator achieves 1% settling time in less than 5uSec for a load variation of 600mA. The sliding-mode controller utilizes a high-bandwidth hysteretic differentiator and an integrator to perform the sliding control law in digital domain. The proposed approach overcomes the steady state error (or DC offset), and limits the switching frequency range, which are the two common problems associated with sliding-mode controllers. The IC is designed and fabricated on a 0.35um CMOS process occupying an active area of 2.72mm-squared. Measured peak efficiency is 83%. / Dissertation/Thesis / Ph.D. Electrical Engineering 2013

Class of 2005 Abstract / Objectives: The purpose was to describe the glycemic control of hospitalized patients treated with sliding scale insulin (SSI) and correlate glycemic episodes to other factors. Methods: The records of 315 patients admitted to a private, 166-bed hospital between August 25 and November 30, 2004 were identified from orders for antidiabetic medications then screened for inclusion and exclusion criteria. 135 of these patients met the criteria for inclusion in this study and their charts were reviewed for demographic data, medical history, medication regimens, blood glucose measurements and SSI use during hospitalization. Hypoglycemia was defined as less than or equal to 50 mg/dL and hyperglycemia greater than 250 mg/dL. Results: Orders for SSI were written for 93% of diabetic patients admitted. 2,904 blood glucose fingerstick measurements were recorded: 15.9% were greater than 250 mg/dL and 0.689% were under 50 mg/dL. The only statistically significant result was the correlation between increased numbers of hyperglycemic episodes and the consumption of the hospital’s “diabetic diet,” p<0.001. The small group of patients admitted for cellulitis (N=6) also experienced more hyperglycemic episodes. There was a trend approaching significance, p=0.055, for an increased number of hyperglycemic episodes in patients with admission blood glucose value over 200 mg/dL. Results based upon the hospital’s standard SSI regimen were not significantly different from other variations of SSI. Implications: SSI was almost always prescribed for hospitalized patients with type 2 diabetes and this regimen resulted in poor glucose control in approximately 17% of fingerstick measurements.

Gun barrels are an important component in advanced defence systems. The gun barrels are used for direct and indirect fire and the material of the gun barrel is exposed to great strains and high temperatures. This sets high demands on the material of the gun barrel. During firing the gun barrel can be damaged. The first damage in gun barrels is the wear of the rifling followed by fatigue. When fatigue occurs cracks can propagate downwards into the bore and could result in catastrophic failure. Therefore investigation regarding the wear, the mechanisms and the underlying factors causing the damage will be performed. How and where the wear in gun barrels occur and also which wear mechanisms causing the wear. Wear in gun barrels involves extreme conditions during firing such as high gas pressure and high temperature from the burning propellant. This thesis work aims to understand how and why wear and damaging mechanisms in gun barrels occurs. Moreover how other ballistic factors influences have on the wear. The wear in gun barrels is caused by erosion from the combustion gases or/and sliding wear caused by the high-speed projectile. The phenomena of wear are complicated and factors like deformation state, types of wear, environment and process are interrelated with each other. These give the rise of wear. In this thesis, samples from three gun barrels were analysed. A new unworn gun barrel, a medium worn gun barrel and a severely worn gun barrel. From the used gun barrels 4 critical positions were identified, then samples from both surface and cross-section were obtained from the gun barrels. The surface and cross-section were analysed using different methods including optical light microscopy and scanning electron microscopy to characterise the surface damage and wear mechanisms. The results from the investigation revealed the dominating wear mechanism to be thermal and chemical erosion at the positions closest to the combustion chamber with heat checks as its signature feature. The heat checks are associated with fatigue cracks developed at the surface and during thermo-mechanical loading, allows it to propagate down into the surface. For both samples at position 2, after the start of the rifling, adhesive wear was obtained too. The adhesive wear was induced by material pick-up from the driving band of the projectile during sliding. In other meaning, the material is transferred from the counter-face to the bore surface. The severely worn gun barrel had been subjected to sliding wear at the muzzle end compared to the medium worn gun barrel which hadn’t experience the same wear rate at the same position. The analysis of the cross-section examination revealed information about the structure and condition of the material. To obtain more information about mechanical properties, a hardness test was performed. The hardness test revealed a hard but brittle surface which can be sheared by the frictional force caused by the sliding projectile. The analysis of the gun barrels revealed information about wear mechanisms and damages in medium and severely worn gun barrels. The detected wear mechanism was thermal erosion, chemical erosion, mechanical erosion and sliding wear.

The work is devoted to the influence of dust particles on the operation of rotating machines with sliding contact. In the work are described and characterized dust particles from environment of selected machines. Their influence on sliding contact and influence on the insulation system of these machines is investigated.

The resolution of spatial data has increased over the past decade making them more accurate in depicting landform features. From using a 60m resolution Landsat imagery to resolution close to a meter provided by data from Unmanned Aerial Systems, the number of pixels per area has increased drastically. Topographic features derived from high resolution remote sensing is relevant to measuring agricultural yield. However, conventional algorithms in Geographic Information Systems (GIS) used for processing digital elevation models (DEM) have severe limitations. Typically, 3-by-3 window sizes are used for evaluating the slope, aspect and curvature. Since this window size is very small compared to the resolution of the DEM, they are mostly resampled to a lower resolution to match the size of typical topographic features and decrease processing overheads. This results in low accuracy and limits the predictive ability of any model using such DEM data. In this dissertation, the landform attributes were derived over multiple scales using the concept of sliding window-based aggregation. Using aggregates from previous iteration increases the efficiency from linear to logarithmic thereby addressing scalability issues. The usefulness of DEM-derived topographic features within Random Forest models that predict agricultural yield was examined. The model utilized these derived topographic features and achieved the highest accuracy of 95.31% in predicting Normalized Difference Vegetation Index (NDVI) compared to a 51.89% for window size 3-by-3 in the conventional method. The efficacy of partial dependence plots (PDP) in terms of interpretability was also assessed. This aggregation methodology could serve as a suitable replacement for conventional landform evaluation techniques which mostly rely on reducing the DEM data to a lower resolution prior to data processing. / National Science Foundation (Award OIA-1355466)

A vertical-style data structure and operations on data in that structure are explored and tested in the domain of sliding window average algorithms for geographical information systems (GIS) data. The approach allows working with data of arbitrary precision, which is centrally important for very large GIS data sets. The novel data structure can be constructed from existing multi-channel image data, and data in the structure can be converted back to image data. While in the new structure, operations such as addition, division, and bit-level shifting can be performed in a parallelized manner. It is shown that the computation of averages for sliding windows on this data structure can be performed faster than using traditional computation techniques, and the approach scales to larger sliding window sizes.

Using the 2009 National Survey of Substance Abuse Treatment Services (N-SSATS), this paper uses logistic regressions to explore the effect of facility ownership on a facility’s show of altruism. Facility’s show of altruism is operationalized as a facility offering free treatment to all its clients, free treatment to some of its clients, or a facility offering a sliding fee scale to its client base in order to absorb some of the cost of treatment based on a potential client's income. Region, receipt of public funds, and religious affiliation are added as covariates in order to gauge whether the potential relationship between facility ownership and a facility’s show of altruism is genuine. Results indicate that private, for-profit ownership status of a facility is associated with a lower likelihood that a substance-abuse treatment facility would engage in altruistic behavior. However, receipt of public funds acts as a mediating variable, in that, its inclusion raises the likelihood that a private, for-profit facility would engage in shows of altruism. Furthermore, it appears that religious-affiliation increases the likelihood that a facility would display altruism by providing free treatment, to some of its clients, or to all, but less likely to display altruism by employing a sliding fee scale. Overall, inclusion of region, receipt of public funds, and religious affiliation all produce statistically significant results, along with facility ownership. This suggests that there are a variety of variables, apart from facility ownership alone, that might be influential over a facility's show of altruism.