The proposed tension measurement method focuses on measurement of tension in a single belt span of the multi-pulley Front End Accessory Drive (FEAD) system. The mean belt span tension is calculated from the measured belt span natural vibration frequency. The oscillation belt span tension is calculated from the measured belt span transverse displacement. The dynamic belt span tension is calculated using the mean and oscillation tensions, belt span support pulley rotations, and belt slip, where the slip equation is based on Euler's equation. The proposed tension measurement method is validated using an experimental testing FEAD system which consists of a five pulley system and an automatic tensioner arm. Non-contact sensors are used to prevent disruption of the typical system behaviour. Testing conditions simulate typical engine crankshaft rotation input. Results from experimental testing consistently produce results with percent error less than 10 % for mean and maximum belt span dynamic tension.

Spacecraft thermal design is an inverse problem that requires one to determine the choice of surface properties that yield a desired temperature distribution within a satellite. The current techniques for spacecraft thermal design are very much in the frame of trial and error. The goal of this work is to move away from that procedure, and have the thermal design solely dependent on heat transfer parameters. It will be shown that the only relevant parameters to attain this are ones which pertain to radiation. In particular, these parameters are absorptivity and emissivity. We intend to utilize an optimal/analytical approach, and obtain a solution via optimization. As mentioned in the motivation, having a purely passive thermal system will greatly reduce costs, and our optimization solution will enable that. This topic involves heat transfer (conduction and radiation), spacecraft thermal network models, numerical optimization, and materials selection.

Master of Science / Department of Mechanical and Nuclear Engineering / Akira Tokuhiro / One of the most deadly tactics used by today’s terrorists is suicide bombing. Sensors have been developed and are being used in different situations to detect weapons and the people initiating suicide bombing attacks. The ideal detection technology would be fast, accurate, effective from long distances, and safe for the both detector and the object being detected. One detector that has shown potential as a tool for detecting hidden weapons is an infrared detector. Infrared detectors are passive sensors that create infrared, or thermal, images without having to expose the subject to any radiation. These images show the heat signature that is given off by objects of interest. Previous studies using infrared detectors for concealed weapon detection have tried to observe the image of the weapon. These have been largely unsuccessful, however, because infrared waves will not readily penetrate clothing. The research presented here determines the feasibility of modeling the heat signature produced by a suicide bomber using thermal models that predict the temperature of the exterior layers of clothing worn. The goal is to be able to compare the images acquired of the suspected bomber to the expected temperatures from the thermal models. If the presence of a hidden weapon affects the emitted heat signature to a point in which the clothing temperatures are not responding as predicted by a model, it is possible a detection system may be created using these models as a comparator and signal for detection. This research also determines a temperature range for which an operator viewing infrared images for suicide bomb detection may be relatively certain of the presence of a foreign object. Testing was also completed to determine those variables that affect an infrared image in ways that help or hinder the use of the thermal models in predicting the temperatures that appear in the infrared images.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Kevin B. Lease / Xiao J. Xin / Peridynamics is a non-local continuum theory that formulates problems in terms of integration of interactions between the material points. Because the governing equation of motion in the peridynamic theory involves only integrals of displacements, rather than derivatives of displacements, this new theory offers great advantages in dealing with problems that contain discontinuities. Integration of the interaction force plays an important role in the formulation and numerical implementation of the peridynamic theory. In this study two enhanced methods of integration for peridynamics have been developed. In the first method, the continuum is discretized into cubic cells, and different geometric configurations over the cell and the horizon of interaction are categorized in detail. Integration of the peridynamic force over different intersection volumes are calculated accurately using an adaptive trapezoidal integration scheme with a combined relative-absolute error control. Numerical test examples are provided to demonstrate the accuracy of this new adaptive integration method. The bond-based peridynamic constitutive model is used in the calculation but this new method is also applicable to state-based peridynamics. In the second method, an integration method with fixed Gaussian points is employed to accurately calculate the integration of the peridynamic force. The moving least square approximation method is incorporated for interpolating the displacement field from the Gaussian points. A compensation factor is introduced to correct the soft boundary effect on the nodes near the boundaries. This work also uses linear viscous damping to minimize the dynamic effect in the solution process. Numerical results show the accuracy and effectiveness of this Gaussian integration method. Finally current research progress and prospective directions for several topics are discussed.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Sameer I. Madanshetty / Cavitation is a long studied phenomenon, fascinating and varied. Observed cavitation thresholds vary, typically ranging from the vapor pressure of the liquid to several atmospheres. Recent studies in cavitation involving very clean liquids give rise to thresholds that surpass 100 atmospheres. Calibrating such high intensity, high frequency, focused acoustic fields presents a significant challenge. The present investigation describes how it is possible to exploit the second order acoustic effect of radiation pressure to seek reliable calibration of the high intensity acoustic fields. Experiments describe how to account for the attendant second order effect of acoustic streaming in the evaluation of the radiation force to accomplish meaningful calibration. Beyond the measurement of the second order quantities associated with cavitation, the work also presents a first investigation of a direct estimation of implosion energies of collapsing bubbles near well-characterized surfaces.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Donald Fenton / Combustion turbine performance deterioration, quantified by loss of system power, is an artifact of increased inlet air temperature and continuous degradation of the machine. Furthermore, the combustion turbine operator has to meet ever changing stricter emission levels. Different technologies exist to mitigate the impact of performance loss and meeting the emission standard. However an upgrade using one or more of the available technologies has associated capital and operating costs. Thus, there is a need for a tool that can evaluate power boosting and emission control technologies in concert with the machine maintenance strategy. This dissertation provides the turbine operator with a new and novel tool to examine each of the upgrades and determine its suitability both from the cost and technical stand point. The main contribution of this dissertation is a tool-kit called the Combustion Turbine Operation and Optimization Model (CTOOM) that can evaluate both power-boosting and emission control technologies. It also includes a machine maintenance model to account for degradation recovery. The tool-kit is made up a system level thermodynamic optimization solver (CTOOM-OPTIMIZE) and two one-dimensional, mean-line, aero-thermodynamic component level solvers for the compressor (CTOOMCOMP1DPERF) and the turbine (CTOOMTURB1DPERF) sections. In this work, the cogeneration system as given by the classical CGAM problem was used for system level optimization. The cost function was modified to include the cost of emissions while the maintenance cost of the combustion turbine was separated from the capital cost to include a degradation recovery model. Steam injection was evaluated for NO[subscript]x abatement, power boosting was examined by both the use of inlet air cooling and steam injection, and online washing was used for degradation recovery. Based on the cost coefficients used, it was seen that including the cost of emissions impact resulted in a significant increase in the operational cost. The outcomes of the component level solvers were compressor and turbine performance maps. It was demonstrated that these maps could be used to integrate the components with the system level information.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Warren N. White / There are a number of different types of mechanical systems which can be termed as underactuated. The degrees of freedom (DOF) of a system are defined by the system’s number of independent movements. Underactuated mechanical systems have fewer actuators than DOF. Some examples such as satellites, air craft, overhead crane loads, and missiles have at least one unactuated DOF. The work presented here develops a nonlinear control law for the asymptotic stabilization of underactuated systems. This is accomplished by finding the solution of matching conditions that arise from Lyapunov’s second method, analogous to the dissipation of energy. The direct Lyapunov approach (DLA) offers a wide range of applications for underactuated systems due to the fact that the algebraic equations, ordinary differential equations, and partial differential equations stemming from the matching conditions are more tractable than those appearing in other approaches. Two lemmas of White et al. (2007) are applied for the positive definiteness and symmetry condition of the KD matrix which is used to define an analogous kinetic energy for the system. The defined KD matrix and the Lyapunov candidate function are developed to ensure stability. The KD matrix is analogous to the mass matrix of the dynamic system. The candidate Lyapunov function, involving the analogous kinetic energy and an undefined potential of the generalized position coordinates, is presented. By computing the time derivative of the Lyapunov candidate function, three equations called matching conditions emerge and parts of their solution provide the nonlinear control law that stabilizes the system. This dissertation presents the derivation of the DLA, provides a new method to solve the first matching condition (FMC), and shows the tools for the control law design. The stability is achieved from the proper shape of the potential, the positive definiteness of the KD matrix, and the non-positive rate of change of the Lyapunov function. The ball and beam, the inverted pendulum cart, and, a more complicated system, the ball and arc are presented to demonstrate the importance of the results because the methods to solve the matching equations, emerging from the system examples, are simple and easier. The presented controller design formulation satisfies the FMC exactly without introducing control law terms that are quadratic in the velocities or approximations. This methodology allows the development of the first nonlinear stabilizing control law for the ball and arc system, a simple and effective formulation to find a control law for the inverted pendulum cart, and a stabilizing control of the ball and beam apparatus without the necessity of approximations to solve the FMC. To illustrate the formulation, the derivation is performed using the symbolic manipulation program Maple and it is simulated in the Matlab/Simulink environment. The dissertation on the solvability of the first matching condition for stabilization is organized into six different chapters. The introduction of the problem and the previous approaches are presented in Chapter 1. Techniques for solving of the first matching condition, as well as the limitations, are provided in Chapter 2. The application of this general strategy to the ball and beam system appears in Chapter 3. Chapter 4 and 5 present the application of the method to the ball and arc apparatus and to the inverted pendulum cart, respectively. The difficulties for each application are also presented. Particularly, Chapter 5 shows the application of the produced material to obtain an easier formulation for the inverted pendulum cart compared to previous published controller examples. Finally, some conclusions and recommendations for future work are presented.

The effects of crosslinking on EVA foaming are studied in this thesis. A fundamental approach was applied to describe the influences of crosslinking on EVA/gas viscosities, gas solubility and diffusivity in EVA, EVA foaming nucleation and early stage of bubble growth, which leads to a better understanding of the plastic foaming mechanism. Although crosslinked polyolefin foaming technology has been well applied in industry, more fundamental and thorough studies are demanded to understand the mechanism, which can serve to improve the present technology. The shear and extensional viscosities have been measured for the chemically crosslinked EVA with dissolved gas which could not be found from literature. Furthermore, by controlling the crosslinking agent amount, the polymer melt strength/viscosity can be controlled, so as to obtain optimum foam morphology. The crosslinking also has effects on the diffusivity and solubility of a blowing agent inside EVA. The solubility and the diffusivity of the blowing agent in the EVA decrease with the crosslinking degree increases. The diffusivity decrease makes more gas is utilized for the foaming rather than leak out of the polymer matrix quickly. This thesis also presents the fundamental studies on the effects of crosslinking on cell nucleation and early bubble growth. Theoretical work and in-situ visualization experimental results indicate that partial crosslinking leads to higher cell nucleation density and slower bubble growth, both of which benefit a fine-cell foam morphology generation. Last but not least, an optimized foaming process was conducted to produce chemically crosslinked EVA foams with large expansion ratios in a batch system, using a chemical blowing agent. The results determine that an optimal crosslinking degree is critical for the crosslinked EVA foaming with maximum expansion ratio. Furthermore, all research results not only benefit the foaming of crosslinked EVA, but also serve the better production of other crosslinked polyolefin foams.

Surface temperature and heat flux measurements were made in a single cylinder SI engine piston when uncoated and with two different surface coatings: a metal TBC and YSZ. A new thermocouple was developed to accurately measure surface temperatures. The engine was operated in a standard full load mode and a knock promoting mode featuring heated intake air and advanced spark timing. Cylinder pressures were measured to quantify knock. It was found that average heat flux into the piston substrate was 33 % higher with the metal TBC and unchanged with the YSZ relative to the uncoated surface. The increase with the metal TBC was attributed to its surface roughness. However, the metal TBC and YSZ reduced peak heat flux by 69 and 77 %, respectively. Both the metal TBC and YSZ reduced knock compared to the uncoated surface. After testing, the metal TBC was undamaged and the YSZ was slightly chipped.

Laser scanning cytometry (LSC) is a slide-based method that is used clinically for Quantitative Imaging Cytometry (QIC). A “Clatch” slide, named after the inventor, which is used in conjunction with the LSC for immunophenotyping patient cell samples, has several drawbacks. The slide requires time consuming and laborious pipette steps, making the slide prone to handling errors. The Clatch slide also uses a significant amount of cell sample, limiting the number of analyses for fine needle aspirate (FNA) samples. This thesis details an automated microfluidic system, composed of an embedded circuit, a plastic and polymer microfluidic device, and an aluminum frame, which can perform the same immunophenotyping procedures. This new system reduces the labor from 36 pipette steps to 8, it reduces the amount of cell sample from 180 μL to 56 μL, and it shortens the entire procedure from 75 minutes to 42 minutes.