Detailed knowledge of tissue mechanical properties is widely required by medical applications, such as disease diagnostics, surgery operation, simulation, planning, and training. A new two degrees of freedom portable device, called Tissue Resonator Indenter Device (TRID), has been developed for measurement of regional viscoelastic properties of soft tissues at the Bio-instrument and Biomechanics Lab of the University of Toronto. As a device for clinical application, the accuracy and reliability of TRID is crucial. This thesis thus investigates the tissue samples’ mechanical properties through finite element analysis method after reviewing the experimental results of the same tissue samples using TRID. The accuracy of TRID is verified through comparing its experimental results with finite element simulation results of tissue mechanical properties. This thesis also investigates the reliability of TRID through experimental study of its indenter misalignment effect on the measurement results of tissue static stiffness, dynamic stiffness, and damping respectively.

This study examined the performance of a residential micro–cogeneration system based on a Stirling engine and fuelled by diesel and ethanol. An extensive number of engine tests were conducted to ensure highly accurate and reproducible measurement techniques. Appropriate energy efficiencies were determined by performing an energy balance for each fuel. Particulate emissions were measured with an isokinetic particulate sampler, while a flame ionization detector was used to monitor unburned hydrocarbon emissions. Carbon monoxide, nitric oxide, nitrogen dioxide, carbon dioxide, water, formaldehyde, acetaldehyde and methane emissions were measured using a Fourier transform infrared spectrometer. When powered by ethanol, the system had slightly higher thermal efficiency, slightly lower power efficiency and considerable reductions in emission levels during steady state operation. To further study engine behaviour, parametric studies on primary engine set points, including coolant temperature and exhaust temperature, were also conducted.

Thin-walled metallic components have been widely used as energy absorbers. One key drawback is the high initial crippling load, which typically results in passenger injuries. It is the objective of this study to introduce taper angle to thin-walled prisms, and to examine the crushing response of thin-walled frusta. Nonlinear finite element models of thin-walled frusta of different cross-sectional geometries were developed. Experimental investigations were conducted to validate these models. The effects of key design parameters on the energy absorption characteristics of frusta were explored. Comparison between thin-walled prisms and frusta show that taper angle helps to reduce the initial crippling load and increase the resistance to global buckling. To take advantage of the interaction effects, a novel multi-frusta configuration was developed and it was shown that the energy absorption efficiency is significantly increased. The results of this work are valuable for enhancing the crashworthiness performance of thin-walled metallic energy absorber.

Thin-walled metallic components have been widely used as energy absorbers. One key drawback is the high initial crippling load, which typically results in passenger injuries. It is the objective of this study to introduce taper angle to thin-walled prisms, and to examine the crushing response of thin-walled frusta. Nonlinear finite element models of thin-walled frusta of different cross-sectional geometries were developed. Experimental investigations were conducted to validate these models. The effects of key design parameters on the energy absorption characteristics of frusta were explored. Comparison between thin-walled prisms and frusta show that taper angle helps to reduce the initial crippling load and increase the resistance to global buckling. To take advantage of the interaction effects, a novel multi-frusta configuration was developed and it was shown that the energy absorption efficiency is significantly increased. The results of this work are valuable for enhancing the crashworthiness performance of thin-walled metallic energy absorber.

The aerosol diluter characteristics of three different systems, the single-stage and the two-stage TSI 379020A rotary disk thermodiluters and Dekati FPS-4000 ejector diluter, were tested using gases and particles over a range of dilution ratios. The upstream and downstream gas and particle concentrations of the diluters were measured in real-time to compute the actual dilution ratio achieved by the three systems. Dilution ratios from approximately 15 to 100 were found to fall within the expected operating error margin of ± 10% for CO2 and CH4. Dilution ratios covering a similar range were also achieved to within ± 10% for particles with diameters from 9.3 to 200 nm. However, when engine exhaust was sampled, significant loss of particles smaller than 29.4 nm occurred during the dilution process. As the dilution ratio increased, the deviation from the expected value increased due to an increase in measurement uncertainty.

The aerosol diluter characteristics of three different systems, the single-stage and the two-stage TSI 379020A rotary disk thermodiluters and Dekati FPS-4000 ejector diluter, were tested using gases and particles over a range of dilution ratios. The upstream and downstream gas and particle concentrations of the diluters were measured in real-time to compute the actual dilution ratio achieved by the three systems. Dilution ratios from approximately 15 to 100 were found to fall within the expected operating error margin of ± 10% for CO2 and CH4. Dilution ratios covering a similar range were also achieved to within ± 10% for particles with diameters from 9.3 to 200 nm. However, when engine exhaust was sampled, significant loss of particles smaller than 29.4 nm occurred during the dilution process. As the dilution ratio increased, the deviation from the expected value increased due to an increase in measurement uncertainty.

Digital Microfluidics (DMF) is a new field of science and technology that introduces movement of nanoliter to microliter size droplets on patterned electrodes. Droplets can be moved, dispensed, merged, and split on devices. Sequential chemical reaction, and DNA extraction are examples of biological applications of DMF. In this thesis, sol-gel technology has been used as a coating method for thin film fabrication. Sol-gel is suitable for coating thin films with flexible shapes. BaTiO3 was used as a dielectric material for coating the insulator layer of the device. The material was spin coated on glass substrates. Devices were coated spinning at 500 rpm for 45 s, and annealed at 600 °C for 2hrs. The ceramic layer obtained, had a thickness of ~1 µm and average roughness of 60 nm. Nanoliter size droplets of water of ~400 nl were moved on the surface of the devices applying minimum voltage of 30 Volts.

This thesis illustrates a comprehensive study on the PVT, solubility and surface tension properties of polylactic acid (PLA) with dissolved CO2 based on thermodynamic models. The solubility of CO2 in PLA melt was calculated by means of a gravimetric method, using a Magnetic Suspension Balance (MSB). The swelling volume of the polymer/gas mixture due to dissolution of gas was compensated for by direct measurement through a view cell or by theoretical models such as Simha Somcynsky (SS) - Equation of State (EOS) and Sanchez Lacombe (SL) - Equation of State (EOS). Three grades of PLA (i.e., PLA3001D, PLA8051D, and PLA4060D) were chosen. It was observed that the pressure, temperature, D-content and Molecular weight variance had an effect on the swelling and solubility. The surface Tension of PLA/CO₂ mixture was also calculated from the captured image using the Axsymmetric Drop Shape Analysis (ADSA). The effects of varying the pressure, temperature, and molecular weight on surface tension were investigated.

The rheological properties of polymer melts and polymer/blowing agent (BA) solutions are determined experimentally and the influences of material rheological properties and crystallization on low-density foaming behaviour of polylactic acid (PLA) are investigated. Understanding the rheological properties of foaming polymers allows the optimization of polymer chemical structure and the development of technologies that produce desired cell morphologies. Although the technology for producing CO2-blown polystyrene (PS) foams is well established, the rheological properties of a PS/CO2 solution, especially its extensional property, are not well understood. In this study, these properties are determined with an in-house developed, online technique, and the measured data are compared with those from commercial rheometers. The online measurement system consists of a tandem foam extrusion system and a die for measuring pressure drops. Shear viscosity is determined from the pressure drop over a straight rectangular channel, while planar extensional viscosity from the pressure drop over a thin hyperbolic channel, taking into account the pressure drop due to shearing. Measured viscosities of the polystyrene without CO2 compare well with those from commercial rheometers. With the presence of dissolved CO2, both the shear and extensional viscosities of the polystyrene are significantly reduced. The influence of CO2 on the two viscosities is found to be similar to an increase of temperature. Polylactic acid is the first mass-produced biodegradable polymer, and has potential to replace petroleum-based polymers in foaming applications. In this study, the influences of material rheological properties and crystallization on the low-density, microcellular extrusion foaming behaviour of polylactic acids (PLAs) are investigated. Comparisons are made between linear and branched PLAs and between amorphous and crystalline PLAs. The branched PLAs are found to produce foams with higher expansion ratios and reduced open-cell content compared to the linear PLA. The foaming behaviour of the linear PLA, then, is significantly improved by adding a small amount of long-chain-branched PLA. The improved cell structure with branched PLAs is attributed to their relatively high melt strength and strain to break. For the first time, it is shown that crystallization, induced by cooling and macroscopic flow during processing, increases melt strength, which aids the production of low-density foams.

Digital Microfluidics (DMF) is a new field of science and technology that introduces movement of nanoliter to microliter size droplets on patterned electrodes. Droplets can be moved, dispensed, merged, and split on devices. Sequential chemical reaction, and DNA extraction are examples of biological applications of DMF. In this thesis, sol-gel technology has been used as a coating method for thin film fabrication. Sol-gel is suitable for coating thin films with flexible shapes. BaTiO3 was used as a dielectric material for coating the insulator layer of the device. The material was spin coated on glass substrates. Devices were coated spinning at 500 rpm for 45 s, and annealed at 600 °C for 2hrs. The ceramic layer obtained, had a thickness of ~1 µm and average roughness of 60 nm. Nanoliter size droplets of water of ~400 nl were moved on the surface of the devices applying minimum voltage of 30 Volts.