The basic function of an electric power system is to supply its customers with electric energy as economically as possible and with a reasonable degree of continuity and quality. Power system reliability evaluation techniques are now highly developed through the work of many researchers and engineers. It is expected that the application of power system reliability evaluation in bulk power systems will continue to increase in the future especially in the newly deregulated power industry. This thesis presents research conducted on the three areas of incorporating multi-state generating unit models, evaluating system performance indices and identifying transmission deficiencies in composite system adequacy assessment. The research was done using a previously developed software package designated as MECORE. Many generating companies in both the traditionally regulated and newly deregulated electrical power industry have large generating units that can operate in one or more derated states. In this research work, load point and system reliability indices are evaluated using two-state and multi-state generating unit models to examine the impact of incorporating multi-state generating unit models in composite system adequacy assessment. The intention behind deregulation in the power industry is to increase competition in order to obtain better service quality and lower production costs. This research illustrates how Canadian power systems have performed in the past using data compiled by the Canadian Electricity Association. A procedure to predict similar indices is presented and used to estimate future performance and the effects of system modifications. The incentives for market participants to invest in new generation and transmission facilities are highly influenced by the market risk in a deregulation environment. An adequate transmission system is a key element in a dynamic competitive market. This thesis presents a procedure to identify transmission deficiencies in composite generation and transmission system. The research work illustrated in this thesis is focused on the application of probabilistic techniques in composite system adequacy assessment and particularly in the newly deregulated electric power industry. The conclusions and the techniques presented should prove valuable to those responsible for power system planning.

The basic function of an electric power system is to supply its customers with electric energy as economically as possible and with a reasonable degree of continuity and quality. Power system reliability evaluation techniques are now highly developed through the work of many researchers and engineers. It is expected that the application of power system reliability evaluation in bulk power systems will continue to increase in the future especially in the newly deregulated power industry. This thesis presents research conducted on the three areas of incorporating multi-state generating unit models, evaluating system performance indices and identifying transmission deficiencies in composite system adequacy assessment. The research was done using a previously developed software package designated as MECORE. Many generating companies in both the traditionally regulated and newly deregulated electrical power industry have large generating units that can operate in one or more derated states. In this research work, load point and system reliability indices are evaluated using two-state and multi-state generating unit models to examine the impact of incorporating multi-state generating unit models in composite system adequacy assessment. The intention behind deregulation in the power industry is to increase competition in order to obtain better service quality and lower production costs. This research illustrates how Canadian power systems have performed in the past using data compiled by the Canadian Electricity Association. A procedure to predict similar indices is presented and used to estimate future performance and the effects of system modifications. The incentives for market participants to invest in new generation and transmission facilities are highly influenced by the market risk in a deregulation environment. An adequate transmission system is a key element in a dynamic competitive market. This thesis presents a procedure to identify transmission deficiencies in composite generation and transmission system. The research work illustrated in this thesis is focused on the application of probabilistic techniques in composite system adequacy assessment and particularly in the newly deregulated electric power industry. The conclusions and the techniques presented should prove valuable to those responsible for power system planning.

Metallic glasses are amorphous alloys that do not possess long-range structural order in contrast to crystalline alloys. Ni-free Ti-based bulk metallic glasses (BMGs) have potential for biomedical applications due to their attractive properties such as high strength, good corrosion resistance and excellent micro-formability, which cannot be obtained for conventional crystalline alloys. In this PhD thesis, Ni-free Ti-based BMGs, i.e. Ti40Zr10Cu34Pd14Sn2 and Ti40Zr10Cu36-xPd14Inx (x = 0, 2, 4, 6, 8), were prepared in the shape of rods by suction casting. Both alloy classes were systematically characterized in terms of glass forming ability, thermal stability, phase formation and mechanical properties. The largest diameter obtained in the fully glassy state for Ti40Zr10Cu34Pd14Sn2 alloy is 3 mm and for Ti40Zr10Cu36-xPd14Inx (x = 2, 4, 6, 8) alloys is 2 mm. Base alloy (Ti40Zr10Cu36Pd14) contains some crystalline phase(s) in the glassy matrix for a 2 mm diameter rod. The structural transformations of Ti40Zr10Cu34Pd14Sn2 BMG upon heating were thoroughly analyzed by utilizing different combination of methods. Firstly, we used differential scanning calorimetry (DSC), X-Ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate the first crystallization event. The main products of the first crystallization are possibly -(Ti, Zr) and Cu3Ti (orthorhombic) phases. Secondly, we employed in situ x-ray diffraction in transmission mode using synchrotron beam to deeply study the thermally-induced structural changes like relaxation, glass transition and crystallization. Since the first peak in the diffraction patterns reflects the structure of the glassy phase on the medium-range scale, the position, width and intensity of this peak in diffraction patterns are fitted through Voigt function below 800 K. All the peak position, width and intensity values show a nearly linear increase with increasing temperature to the onset temperature of structural relaxation, Tr = 510 K. However, these values start to deviate from the linear behavior between Tr and glass transition temperature Tg. The changes in the free volume, which was arrested during rapid quenching of the BMG, and the coefficient of volumetric thermal expansion prove that the aforementioned phenomenon is closely related to the structural relaxation. Above 800 K, three crystallization events are detected and the first exothermic event is due to the formation of metastable nanocrystals. For the Ti40Zr10Cu34Pd14Sn2 alloy, 2 mm diameter rods exhibit the best combination of mechanical properties (e.g. large plastic strain and high yield strength) among all the diameters (ø2, ø3 and ø4 mm) under the room-temperature compression tests. With the aim to improve its room-temperature mechanical properties, the processes of pre-annealing and cold rolling have been applied for the 2 mm diameter rods. Annealed and quenched specimens below Tg and in the supercooled liquid region (between Tg and onset crystallization temperature Tx) do not lead to the enhancement of the plasticity compared to as-cast alloys due to annihilation of excess free volume and crystallization. Cold rolling can effectively improve the plasticity of this BMG by inducing structural heterogeneities. Rolled samples up to a thickness reduction of 15% result in the largest plasticity of 5.7%. Low yield strength and visible work hardening ability are observed in the both 10%-rolled and 15%-rolled samples. The deformation behavior of Ti40Zr10Cu34Pd14Sn2 BMG at the elevated temperatures slightly below Tg and in the supercooled liquid region has been investigated. The stress-strain relations for this BMG over a broad range of temperatures (298 ~716 K) and strain rates (10-5 to 10-3 s-1) were established in uniaxial compression. Under compression tests at the highest test temperature of 716 K, the Ti-based BMG partially crystallizes and low strain rates can lead to the formation of larger volume fractions of crystals. In order to further improve the plasticity of Ti-Zr-Cu-Pd BMGs and simultaneously reduce the content of Cu (considering harmful element for the human body), the Ti40Zr10Cu36-xPd14Inx (x = 2, 4, 6, 8) BMGs have been newly developed with different short- or medium-range order in the structure. The compressive global strain of Ti40Zr10Cu36-xPd14Inx (x = 0, 2, 4, 6, 8) can be significantly improved from 4.5% for the In-free alloy to 10.2% for x = 4. However, a further increase of the indium content to 8 at.% results in a decrease of the plasticity. Among all the monolithic Ni-free Ti-based BMGs reported so far, the novel Ti40Zr10Cu32Pd14In4 BMG shows the largest plasticity. Inspired by the dislocation concept in crystalline materials, we propose a strategy for the design of ductile BMGs through minor substitution using relatively large atoms, which make the bonding nature become more metallic and with it less shear resistant. Such a locally modified structure results in topological heterogeneity, which appears to be crucial for achieving enhanced plasticity. This strategy is verified for Ti-Zr-Cu-Pd glassy alloys, in which Cu was replaced by In, and seems to be extendable to other BMG systems. The atomic-scale heterogeneity in BMGs is somewhat analog to defects in crystalline alloys and helps to improve the overall plasticity of BMGs.

This dissertation describes a structural investigation of hyaluronan (HA) with neutron scattering techniques. HA is a natural biopolymer and one of the major components of the extracellular matrix, synovial fluid, and vitreous humor.  It is used in several biomedical applications like tissue engineering, drug delivery, and treatment of osteoarthritis. Although HA is extensively studied, very little is known about its three-dimensional conformation and how it interacts with ions and other molecules. The study aims to understand the bulk structure of a cross-linked HA hydrogel, as well as the conformational arrangement of HA at solid-liquid interfaces. In addition, the structural changes of HA are investigated by simulation of physiological environments, such as changes in ions, interactions with nanoparticles, and proteins etc. Small-angle neutron scattering and neutron reflectivity are the two main techniques applied to investigate the nanostructure of hyaluronan in its original, hydrated state. The present study on hydrogels shows that they possess inhomogeneous structures best described with two correlation lengths, one of the order of a few nanometers and the other in the order of few hundred nanometers. These gels are made up of dense polymer-rich clusters linked to each other. The polymer concentration and mixing governs the connectivity between these clusters, which in turn determines the viscoelastic properties of the gels. Surface-tethered HA at a solid-liquid interface is best described with a smooth varying density profile. The shape of this profile depends on the immobilization chemistry, the deposition protocol, and the ionic interactions. HA could be suitably modified to enhance adherence to metal surfaces, as well as incorporation of proteins like growth factors with tunable release properties. This could be exploited for surface coating of implants with bioactive molecules. The knowledge gained from this work would significantly help to develop future biomaterials and surface coatings of implants and biomedical devices.

No description available.

No description available.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.

The purpose of this project is to reexamine established free-radical polymerization theories and build a mechanistic reactor model for multi-component (up to six monomers) bulk and solution polymerizations under batch/semi-batch reactor configurations. The six-monomer system of interest is: Styrene (Sty), n-Butyl acrylate (BA), Butyl methacrylate (BMA), Hydroxyethyl acrylate (HEA), Hydroxybutyl acrylate (HBA), and Acrylic acid (AA). In order to develop a flexible, comprehensive, and user-friendly model, not only a physical/kinetic database of individual monomers and ingredients such as solvents, initiators, and chain transfer agents, but also a co-polymer database of reactivity ratios, and glass transition temperatures were built and combined with the modeling steps. Through an extensive literature search for polymerization models and kinetics, the simulation model was developed in a general way to cover the range from homo- to hexa-polymerization at both regular and elevated temperature levels, and explain various polymerization kinetics and characteristics. Model testing was conducted with experimental data as much as possible to check the model’s reliability. Due to limited experimental data for higher multi-component polymerizations, the simulation model was tested with homo-polymerizations and other available cases of combinations of two to four monomers. Very reasonable agreement was found between model predictions and experimental data on rate of polymerization, molecular weight, polymer composition, sequence length, etc. through the entire conversion. This multi-component modeling study continuously requires experimental checkups and parameter fine-tuning for better predictions. Further literature search or experimental studies still remain necessary for the hydroxyalkyl acrylate kinetic database and model testing of the depropagation feature. Sensitivity analysis also could be performed to locate critical parameters. This model should find use in industry for analyzing and optimizing reactor conditions as well as in the academic field as a research and educational tool.

This thesis discusses non-linearities associated with a sampling switch and compares transmission gate, bootstrapping and bulk-effect compensation architectures at circuit level from linearity point of view for 0.35 um CMOS process. All switch architectures have been discussed and designed with an additional constraint of switch reliability. Results indicate that for a specified supply of 3.3 Volts, bulk-effect compensation does not improve third-order harmonic distortion significantly which defines the upper most limit on linearity for a differential topology. However, for low-voltage operations bulk-effect compensation improves third-order harmonic noticeably.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.