title: The Melting Behaviour of Coal Ore Composites

subject: melting behaviour coal ore

abstract:
A breakthrough ironmaking technology (1Tmk3) produces iron separated from slag by heating coal-iron ore composite pellets at temperatures as low as 1325C in about 10 minutes. Other researchers have studied the melting behavior, including the formation of a dense metallic shell separated from slag but the mechanism has not been yet fully understood. Exploring this knowledge gap was targeted in this study. The initial experiments included heating of composite samples at different temperatures and time intervals. Three coal types and two coal/ore ratios were investigated. By these experiments slag free iron production at low
 temperature and short time was confirmed. Coal type and coal/ore ratio were found to have a
significant effect on melting behavior. The main series of experiments focused on the effect of slag composition mainly CaO and Si02, slag content and reaction time on the melting behavior. The main characterization methods included Optical Microscopy, Energy
Dispersed X-ray Analysis (EDX), and simultaneous Differential Thermal Analysis (DTA), and Thermo Gravimetric Analysis (TGA). Despite most of the obtained results being qualitative, this study was successful in exploring some of the most important reasons behind the melting behavior of coal ore composites. It was revealed that the formation of a low melting point slag containing FeO in the core of the pellet and its exudation to the iron shell is responsible for the formation of a dense metallic shell. Densification of iron occurs by reduction of FeO in slag. The rate and extent of reduction is related to the physical properties of slag that in turn is influenced by slag composition. More basic slags tend to have higher rate of FeO reduction in slag. By reduction of FeO in slag, the interfacial tension of the remaining slag with iron increases and slag is separated from iron.

abstract: Thesis

abstract: Master of Materials Science and Engineering (MMatSE)


title: Adaptive Machine Vision for Automotive Component Inspection

contributor:
Bone, Gary M.
Mechanical Engineering

subject: machine vision inspection

abstract:
Although the consistency, low cost, and high speed of machine vision systems make them suitable for many areas of manufacturing, there exist challenges for online inspection using machine vision systems due to the presence of variations in lighting, part position/orientation and part finish. In this thesis, a novel adaptive machine vision system based on pixel-by-pixel analysis and a neural network based vision system are presented to solve two challenging industrial inspection problems. Both of the vision systems stem from the idea of adaptive image processing to analyze an image with respect to its local properties. In the first part of the thesis, a pixel-by-pixel analysis based adaptive vision system is designed for an automotive water pump housing surface inspection problem. This vision system is used to inspect the machined surface of a die-cast part. The defects on this part may include pores, dents and scratches. This problem is challenging for several reasons. First, non-uniform surface finish on the parts produces large brightness variations that must be reduced using a controlled lighting work cell and adaptive camera control. Second, the defects can be subtle and less than lmm in diameter, while the surface is roughly 180mm by llOmm. Third, the surface often includes machining marks that appear similar to defects in the image, but are not considered defects. Finally, due to the manufacturing and fixturing variations, the size and location of the area to be inspected varies considerably, so that a simple fixed mask cannot be used to separate this area from the rest of the image. These challenges have been overcome by developing an adaptive machine vision system. This system includes custom-designed controlled lighting, and several software algorithms for adapting to the variations in surface quality and geometry. The system can detect defects as small as 0.15 mm. It has been tested with over 1,700 images that were collected at the factory. The majority of the defects were
pores. These pores were correctly classified in 93% of the cases. In the second part of the thesis, a neural network-based vision system is developed for an automotive beam clip present/absent inspection problem. In this inspection problem, it is difficult to obtain the theoretical expression for the conditions of 'clip present', 'clip absent' and also for the clip orientation. Furthermore, there exist strong variations in this inspection problem, such as changing lighting conditions, environmental disturbances, clip locations and clip orientations. A CMAC neural network-based vision algorithm is developed to overcome these challenges. The CMAC neural network has the ability to learn fast and is suitable for real-time inspection applications. This vision system is demonstrated to correctly classify 100% of the cases, for the given automotive part images, after being trained for 151 seconds.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Design and Control of a Closed-Circuit Servo-Controlled Miniature Hydraulic Rotary Joint

subject: closed-circuit hydraulic

abstract:
In the last few decades, miniaturization has been in increasing demand in many applications. The miniature actuators should comprise high power-weight ratio while having a fast dynamic response, and high efficiency. In this thesis several approaches have been studied to develop a low pressure water hydraulic system driving a miniature rotary joint as the end-effecter. While the system was expected to have a cross sectional diameter of 15 mm, two prototypes were manufactured having cross sections of 12.5 mm X 13 mm (18 mm dia.) and 16 mm X 18 mm (24 mm dia.). The system involves a novel closed-circuit water hydraulic system in which a controlled volume of water supplied by a motor-cylinder pump drives the rotary joint cylinders (4 mm bore). The linear motion of these cylinders is converted to a rotational motion through a sliders-pulley mechanism. The rotation of an arm attached to this pulley is measured by a magnetic rotary encoder. The dynamic behaviour of the system was studied and the most important parameters have been modelled. This model has been utilized in the design of a model based feedforward (FFWD) controller which was added to a PID controller to enhance the position control of the rotary arm. Numerous experiments were conducted with the horizontal rotation of the rotary arm. The maximum error ( emax) recorded for a mixed
input (a combination of rising and falling cycloidals of 120° and 60° with pause periods
of 1 and 0.5 s) with a PID controller was 8.3° while with the addition of the FFWD term
this dropped to 6.2°. The maximum root mean square error (RMSE) for the same
trajectory has been 1.7° and 0.9° for PID and FFWD+PID controllers respectively. The
steady state error (SSE) which was measured during a eycloidal input of 120° was recorded to be in the range of ±0.2° for both of the controllers. The robustness of the controllers was evaluated by adding a mass of 8.5 g to the end of the rotary arm which produced an un-modelled extra large inertia to the system dynamic when the arm rotating horizontally. Robustness of both controllers was demonstrated as the change in the main numerical performance indicators (RMSE, ernax, and SSE) were not remarkable. Another set of experiments performed with the rotary joint positioned vertically introduced with an un-modelled changing force. The numerical performance indicators were almost unchanged again. A comparison between the results of this thesis with the ones from the previous work in our laboratory by R. Sindrey indicates a significant improvement.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Enhanced Conditions for High Performance Machining of Hardened H13 Die Steel

contributor:
Veldhuis, Stephen
Mechanical Engineering

subject:
high performance machining
H13 die steel

abstract:
The availability of sophisticated machine tools, together with advanced cutting tool designs and high performance coatings has allowed machining to meet many challenges. A significant remaining challenge is the competitive milling of hardened steels at moderate to high cutting speeds. This is of particular importance for the die and mould making industry. Despite the necessity to achieve higher production rates and improved surface finish, cutting speeds above the range of 300-600 m/min are still not possible. This limitation is due to the combination of high mechanical, thermal and chemical interactions that are taking place on the tool surface during cutting. To address this situation, an extensive amount of research has been focused on developments associated with hard coatings such as nano-multilayered hard PVD coatings that exhibit novel mechanical and thermal properties. The development of
methodologies for designing a cutting tool with a strong cutting edge micro-geometry has
set guidelines for selecting proper cutting edge preparation for specific cutting applications.
The results indicate that, the development of new hard coating designs is the most effective way to improve the service life of coated carbide tools for hard high speed milling applications. The developments of both robust and rigid substrate designs with adaptive cutting edge micro-geometries assist the cutting tool performance by favoring the surface adaptability of the deposited coating. The developments of different strategies for dry air cooling that provide a "soft-cool" environment seem to have a beneficial impact on cutting performance and tool life improvement. Dry air cooling is found to be more effective than chilled-air cooling and minimum-quantity-lubrication (MQL). Therefore, the utilization of a cutting environment tailored to meet the requirements of both the tool and the coating while providing sufficient air flow to remove chips from the cutting zone will complement the adaptability of the whole tool-workpiece-chip system.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Comparison of Traveling Wave and Gain-Clamped Semiconductor Optical Amplifiers and Impact of Dispersion on Hybrid of Frequency-Hopped Optical CDMA and WDMA Networks

contributor:
Huang, Wei-ping
Electrical and Computer Engineering

subject:
wave
gain-clamped semiconductor
dispersion
CDMA
WDMA

abstract:
(This thesis consists of two parts.) Part I Comparison of Traveling Wave and Gain-Clamped Semiconductor Optical Amplifiers. Today's Wavelength Division Multiplexing (WDM) optical networks are getting dynamic light-path reconfigurable and optical transparent. Optical
 amplification without optoelectronic conversion is a key technology in all-optical networks.
 semiconductor optical amplifier (SOA) is a very potential device in this field. Besides the linear amplification, the nonlinear features of SOA make it has a broad application in wavelength conversion, tunable wavelength filter, optical switching and optical logic. The simple structure and very compact size of SOA indicate the essential low-cost and compatibility of integration. Resonant cavity is the basic structure of conventional SOAs, while gain-clamped SOAs (GC-SOAs) provide a constant gain which raises a lot of interests in applications. SOA with Distributed Bragg Reflectors (DBR) is one of the structures to realize the clamped gain. In this thesis the performances of traveling wave SOA (TW-SOA) and DBR-SOA are compared through a dynamic model. This model consists of a distributed feedback wave equation, a carrier rate equation and a material gain model, thereby can be used to simulate both of the two SOAs. To balance the time cost of simulation and the accuracy of the result, three important non-physical parameters, simulated bandwidth, cavity discritization and frequency discretizaiton, are investigated. The simulation results show that DBR-SOA has a very stable device gain which is independent on input optical power. From a noise level point of view DBR-SOA and TW-SOA have different characteristics. These comparison is conducted with both large signal input and small signal input. In addition, a desirable application, SOA in a multi-channel WDM system, is also simulated with GC-SOA and TW-SOA. The Bit Error Rate (BER) of TW-SOA increases greatly due to inter-channel cross talk, while the BER of GC-SOA is virtually constant with the variation of WDM channel number. Another application, wavelength converter, shows TW-SOA is very useful in non-linear application.
Part II Impact of Dispersion on Hybrid of Frequency-Hopped Optical CDMA and WDMA Networks. A new analytical formula for analysis of the system performance of the Hybrid of Wavelength Division Multiple Access (WDMA) and Code Division Multiple Access (CDMA) is developed and presented. The effects of fiber dispersion and inter-channel crosstalk are considered and their impact on system performance is analyzed in terms of power penalty. Finally, methods to overcome the effects of the fiber dispersion are discussed.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: THE SEVEN LAWS OF NOAH OR NOVAK:  AN ANALYSIS OF DAVID NOVAK’S ACCOUNTS OF NATURAL LAW

contributor:
Planinc, Zdravko
Religious Studies

subject: David Novak, Noahide Code, Natural Law, Redemption

abstract: This thesis identifies two accounts within David Novak’s Jewish natural law theory. In the earlier account, Novak locates natural law within the Noahide commandments; in the later account, he also locates it within the reasons for the commandments and rabbinic enactments. The change between these accounts is marked by a shift in his description of rationality. The norms of the Noahide code are originally described as known strictly by reference to themselves. As he begins grounding the norms in the imago Dei, that knowledge becomes dependent on a “cultural heritage,” by which Novak comes to mean an explanation based on a doctrine of creation. By comparing the original presentation of the later account with its more developed iteration and highlighting the features that are unique to the earlier and later accounts, it becomes possible to identify components of the later account that are added to his subsequent treatment of the Noahide code and facets of the earlier account that are later added to his discussion of the reasons for the commandments and rabbinic enactments. These efforts at reconciliation include the normative content incorporated into the later account, the metaphysical background added to the later treatment of the Noahide code, the mediating concept of personhood, the phenomenological retrieval of the Noahide commandments, and the argument for minimal and maximal claims. Finally, this thesis analyzes the relationship between Novak’s natural law theory and his view of redemption. Given that as Novak’s natural law theory becomes less dependent on reason and more heavily based on a doctrine of creation, his treatment of redemption changes from being associated with a period of greater human understanding to a time that is characterized by God’s accomplishments on humanity’s behalf, I argue that there is a parallel between those concepts. I then draw on that parallel to show that Novak’s natural law is compatible with, and perhaps inseparable from, his covenantal thought.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Inuit medical evacuees and tuberculosis in Hamilton: the makings of a problem

contributor:
Satzewich, Victor
Sociology

subject:
Inuit
tuberculosis
Indigenous
social determinants of health
claims-making
social problems
resource dependency

abstract: In early twentieth century Canada, the tuberculosis (TB) epidemic struck far and wide (Herring, 2007) and its effect was greater on indigenous populations, particularly the Inuit (Public Health Agency of Canada, 2013). In 1906, the Mountain Sanatorium was founded by the Hamilton Health Association (HHA) in an effort to curb the disease (Wilson, 2006) and was designated as a treatment centre for Inuit from the Eastern Arctic. Controlling TB became a movement extensively documented by The Hamilton Spectator – a prime news provider. This research concerns the way in which social problems emerge and the responses they generate. Drawing on the literature on social problems, this thesis examines the HHA’s claims-making activities regarding tuberculosis in 1953-1963 along with The Spectator’s role in helping to define TB as a problem. It examines 1) how the HHA constructed TB as a problem 2) how the HHA understood the problems and solutions of tuberculosis; 3) it ascertains whether the HHA and The Spectator drew from a biomedical model or considered social determinants of health (SDOH) in their control and reportage of the disease; 4) the portrayal and treatment of Inuit patients; 5) the role of legitimacy; and 6) the importance of Pfeffer and Salancik’s resource dependency theory in the Sanatorium’s efforts to survive as an institution. This was executed through a content analysis of the HHA’s annual reports and newspaper articles by The Spectator. The examination of this case through the theory of social problems and resource dependency provides a lens to understand how TB became a problem and why hospitals are more than treatment facilities.

abstract: Thesis

abstract: Master of Arts (MA)


title: Nanocomposite Coatings for Biomedical Applications

contributor:
Zhitomirsky, Igor
Materials Science and Engineering

subject: nanocomposite coatings, biomedical applications, electrophoretic deposition methods, corrosion protection, stainless steel, Nitinol

abstract:
 New electrophoretic deposition methods for the fabrication of advanced organic-inorganic
composite coatings on metallic substrates for biomedical applications have been developed. In the proposed methods, chitosan was used as a matrix for the fabrication of multilayer and functional graded chitosan- hydroxyapatite (HA) coatings. The HA particles showed preferred orientation of c-axis parallel to the layer surface, which is similar to the bone structure. Electrochemical studies showed that the obtained coatings provided corrosion protection of the metallic substrates, such as stainless steel and Nitinol.

 The feasibility of co-deposition of chitosan and heparin has been demonstrated. Composite chitosan-heparin layers were used for the surface modification of chitosan-HA coatings. Obtained results paved the way for the electrophoretic fabrication of novel coatings for biomedical implants with improved blood compatibility.

 The feasibility of co-deposition of hyaluronic acid and HA has also been demonstrated. The co-deposition of hyaluronic acid and HA resulted in the fabrication of novel nanocomposite films by electrodeposition. The chemical composition,
microstructure, corrosion protection, and other functional properties of the nanocomposites have been investigated. Co-deposition of hyaluronic acid and multiwalled carbon nanotubes has been studied by TGA/DT A and SEM studies.

 The feasibility of deposition of novel composites based on alginic acid has been demonstrated. New electrochemical strategies were used for the fabrication of alginic acid-HA, alginic acid-heparin and alginic acid -hyaluronic acid nanocomposites. The composition of these nanocomposite coatings can be varied by variation in bath composition for EPD.

 The electrochemical mechanisms for the fabrication of all these advanced organic-inorganic composite coatings have been developed.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Response of Ecosystem Evapotranspiration to Water-Stress in a Temperate Deciduous Forest in southern Ontario

contributor:
Arain, Altaf
Earth and Environmental Sciences

subject: Evapotranspiration

abstract:
Seasonal droughts are becoming more prevalent in recent years as a result of climate change and associated fluctuations in precipitation events. Forested ecosystems react very differently to changes in the hydrological cycle in different regions. This study investigates how atmospheric water fluxes react to changes in meteorological variables and subsurface hydrological conditions in a 90-year old temperate deciduous forest in southern Ontario, Canada, using eddy covariance flux data over five years (2012-2016).

Results show that although drought occurrences in 2012, 2015 and 2016 put stress on the forest ecosystem, with significantly varying climate and soil conditions, no substantial impact on forest evapotranspiration appeared to occur. Annual eddy-covariance mean evapotranspiration of the study was 382 ± 46 with a growing season average of 353 ± 36. Highest annual evapotranspiration (422 mm) occurred in 2012 with 389 mm occurring during the growing season while the lowest annual evapotranspiration (341mm) occurred in 2014 with 316mm occurring in the growing season. Air temperature and vapour pressure deficit had the dominant control on evapotranspiration as expected, with the highest sensitivity occurring during drought years. Soil water potential (SWP), as the soil moisture stress proxy, reached maximum values during drought years, but was not found to have a significant control with evapotranspiration. SWP peaked when evapotranspiration values reach maximums combined with warm air temperatures, progressively increasing when precipitation input was minimal. Our results indicate that evapotranspiration rates in this forest ecosystem were predominantly determined by atmospheric controls when accessibility of deep soil water was possible. These findings suggest that temperate deciduous forests were able to sustain  ET during low to moderate intensity droughts and observed over the study period due to their ability to access deep soil moisture stores during periods of stress. However, these forests may experience significant declines in ET if severe or multi-year drought conditions arise, similar to those that occurred in the last two years of this study. These conclusions will help to elucidate how ET in deciduous forests will respond to future climate regimes in this region.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: With seasonal droughts occurring more frequently from climate change, water required by tree species may reach limitations to sustain atmospheric demand. In particular, temperate deciduous forests, that are common in the northern hemisphere, may be affected due to predicted future climate scenarios. It is important that we understand how they will respond to future climate conditions. Understanding how forest evapotranspiration is affected by various meteorological and hydrological parameters will help gauge how forests will cope with limiting water resources in the future. An assessment of a temperate deciduous forest in southern Ontario, which is part of the Turkey Point Flux Station, was conducted in this study over 5 years (2012-2016). Over this period the forest experienced varying drought intensities. Results show that air temperature and vapour pressure deficit were the dominant controls on forest ET during times of water limitations. The forest was able to withstand low-moderate droughts by accessing deep soil water stores to keep up with the extreme demand. This study suggests that temperate deciduous forests in the region are well adapted to drought stress and they may be able to cope with similar intensity droughts in the future by maintaining water flow.


title: Microfluidics devices for Drosophila-based drug discovery assays

contributor:
Selvaganapathy, Ponnambalam Ravi
Mechanical Engineering

abstract:
Drosophila  melanogaster  has  long  been  a  preferred  model  organism  for  the  study  of
developmental, genetic,  and  biochemical  processes. They  have only  four chromosomes
and  a  comparably  simple  morphology.  Given  that  60%  of  Drosophila  proteins  share
homologs with humans, this allows for the effective study of biological processes that are
of importance in human and vertebrate models. The conventional drug discovery assays
using Drosophila are manual and require skill operator, which makes them expensive and
unsuitable  for  high-throughput  screening.  Hence,  technologies  to  address  the  existing
challenges involved in the conventional Drosophila-based assays (either in embryonic or
larva  stage)  would  greatly  facilitate  drug  discovery  process.  In  this  thesis,
microfabrication  and  microfluidics  engineering  approaches  have  been  utilized  in
Drosophila-based  assays  due  to their  potential  to obtain  high  accurate  positioning  and
reagent  delivery  in  a  low-cost,  rapid  and  potentially  automated  manner.  At  embryonic
stage, the first microinjector that allow one to precisely insert a long taper microneedle
laterally  and  at  various  positions  inside  the  length  of  the  Drosophila  embryo  (up  to
250µm)  was  developed.  Using  this  device,  it  was  demonstrated  that  the  cardioblast
migration  velocity  is  modified  in  a  dose  sensitive  manner  to  varying  doses  of  injected
Sodium  Azide  (NaN3).  At  larva  stage,  a  systematic  analysis  of  various  mechanical
constrictions  incorporated into microfluidic channels were conducted. This could allow
one to find an optimized design for rapid mechanical immobilization of larvae for whole-
CNS imaging. The optimal immobilization mechanism has been used for immobilization
and live-intact fluorescence functional imaging of Drosophila larva's CNS in response to
controlled  acoustic  stimulation  using  a  Genetically  Encoded  Calcium  Indicator  (GECI)
probe,  called  GCaMP5.  The  microfluidics  clamps  developed  could  immobilized
Drosophila  larvae  for  only  whole-CNS  imaging  and  they  cannot  allow  one  to  capture
neuronal responses at single-neuron resolution, which requires stronger immobilization.
In  this  thesis,  a  simple  microfluidic  device,  which  employed  an  interesting  strategy  to
completely  immobilize  the  brain  and  the  CNS  of  a  live,  fully-functioning  Drosophila
larva was demonstrated. This enables one, for the first time, to imaging throughout these
organs  at  a  single  neuron  resolution.  None  of  the  mechanical  immobilization  methods
available currently are capable of immobilization of the brain and the CNS of a live fully
functioning  Drosophila  larva  for  intact  imaging  at  a  single  neuron  resolution.  The
application  of  this  platform  was  not  limited  to  brain  and  CNS  imaging  and  it  can
potentially being used to record neuronal events at different organs such as gut, intestine
and hearts in a fully intact manner.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Pattern Recognition of Arabic/Persian Handwritten Digits using Adaptive Boosting, Neural Networks and Deep Boltzmann Machines

contributor:
McNicholas, Paul D
Mathematics and Statistics

abstract:
Classification of handwritten numerals has captured the attention of the statistical and machine learning community. A common statistical approach is ensemble learning, which combines basic classifiers to produce one powerful predictor. Another popular method is neural networks, which is a non-linear two stage statistical model inspired by the biological neural networks. In this thesis, neural networks (nnet), adaptive boosting (AdaBoost), and deep Boltzmann machine (DBM) algorithms are tested for Arabic/Persian handwritten digits, and their recognition performance is
then compared.

abstract: Thesis

abstract: Master of Science (MSc)


title: Characterization of Amorphous Silicon (α-Si) and Silicon Rich Silicon Oxide (SiOx) Materials Produced by ECR-PECVD

contributor:
Mascher, P.
Engineering Physics

subject: amorphous silicon, silicon rich silicon oxide

abstract:
Silicon based materials, including silicon oxides and silicon oxynitrides, have found
use in a number of areas in photonics including waveguides, antireflection and highly
reflective coatings for laser facets, and detectors. For effective use of these materials
in photonics it is necessary to characterize their optical properties as a function of
their composition and structure. Since these characteristics are often dependent on
the method used to deposit the films it is necessary to also determine the effect of
deposition type and conditions on the film's properties.
Recently, silicon based materials have been seen to display luminescence due to
quantum confinement effects when nanocrystals are formed. This opens up the possibility
of a silicon based emitter, something that has not had previous success due
to the indirect bandgap of bulk silicon. The development of a silicon based emitter
in turn would open up the possibility for monolithically integrated photonic circuits
that could take advantage of CMOS processing technology.
This thesis presents the results of research into the characterization of amorphous
silicon and silicon oxide thin films deposited by electron cyclotron resonance plasma
enhanced chemical vapor deposition. Optical properties of the films have been determined
through the use of ellipsometry and correlated with the results from compositional
analysis, done using Rutherford backscattering and elastic recoil detection,
and bonding structure analysis, done using Fourier transform infrared spectroscopy.
Nanocrystals were formed within the films by subjecting them to post-deposition thermal
annealing, which induces a phase separation in silicon rich silicon oxide films. The
effects of different annealing conditions on composition, structure and optical properties
have also been analyzed. Finally, photoluminescence experiments were conducted
on the films and correlated with the results from other characterization techniques.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Comparative CT Densitometry in Murine Pulmonary Disease Models

contributor:
Labiris, N. R.
Physiology and Pharmacology

subject:
CT densitometry
murine
pulmonary
disease model

abstract:
Using micro-computed tomography it is possible to detect the presence of pathologies which alter the lung's normal density. The density of the lungs can be altered depending on the amount of air, tissue, cells or fluid they contain. Using established mouse models of house dust mite (HDM) induced asthma, TGF-J31 induced pulmonary fibrosis (PF) and lipopolysaccharide (LPS) induced neutrophilic inflammation, this thesis examines if CT densitometry can distinguish between different pathophysiological processes. An airway segmentation method was applied to the CT images and data from these regions were assessed to determine: first, if pathologies can be detected compared to control
animals; secondly, if pathological progression within each model can be measured; and finally, if it is possible to distinguish between the pathologies themselves. Lung histology and bronchoalveolar lavage fluid cytology, and total lung resistance (for the asthma model only) were assessed to confirm the disease models. The results showed that a healthy lung can be distinguished from a diseased lung in all three models. Pathological progression and resolution were also visible in the asthma and LPS groups. No changes were noted between the examined time points in the PF model. This corresponded to histological findings. It is
also possible to distinguish between many of the pathologies based on the density profiles alone. Thus, CT densitometry affords a non-invasive method to longitudinally assess disease progression and resolution which is useful for the testing of novel therapeutics within the same subject. Regional CT density assessment, allows for the detection of localized
pathologies around the airways which whole lung assessments may not be sensitive enough to detect.

abstract: Thesis

abstract: Master of Science (MSc)


title: Characterization of PMN-35PT Thin Film Relaxor Ferroelectric

contributor:
Botton, Gianluigi
Materials Science and Engineering

subject: ferroelectrics

subject: PMN-35PT

abstract: High quality epitaxial thin films oflead magnesium niobate -lead titanate (PMN0.35PT) were deposited on MgAh04 substrates in the (001) direction with a lattice mismatch of less than 2%. Characterization by transmission electron microscopy and xray diffraction, has revealed high quality single crystal epitaxial thin films oriented in the (001) direction with a tetragonal unit cell. Capacitance measurements were completed by interdigital dielectrometry and using Finite Element Modeling the dielectric constant for the thin film yielded values ranging from 561 -799 at lk:Hz and 518-746 at 100kHz when the temperature was varied from 273-473K. Additionally, the dielectric maximum has been shifted to higher temperature and the  frequency dispersion of the dielectric constant appears to be minimized. Piezoresponse microscopy and transmission electron microscopy was completed on both single and multilayer heterostructures. Transmission electron microscopy shows that the single layer samples show excellent morphology with single crystal epitaxial growth in the (001) direction. In addition piezoresponse microscopy and TEM have elucidated the difficulty in producing high quality films of PMN-0.35PT with a BaNb0.5Ti0.503 bottom electrode. The tendency for columnar growth of BaNb0.5Ti0.503 establishes an environment for polycrystalline growth drastically reducing the probability of single crystal growth in subsequent layers. Finally, piezoresponse microscopy allowed the observation of self polarization in PMN-0.35PT within the polycrystalline films which is in agreement with observations of previous researchers.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Physiological Assessment of Hearing Aid Compression Schemes

contributor:
Bruce, Ian C.
Electrical Engineering

subject: physiological assessment, hearing aid, compression scheme, linear amplification, speech material

abstract:
 Nonlinear amplification schemes for hearing aids have been developed to deal primarily with the problem of loudness recruitment. The most commonly used form of nonlinear amplification is wide-dynamic-range compression (WDRC). Unfortunately, finding WDRC characteristics that satisfactorily deal with loudness recruitment while maintaining good speech intelligibility has proven difficult. An alternative nonlinear scheme, Advanced Dynamic Range Optimization (ADRO), has been shown in several studies to provide better speech intelligibility and listening comfort than fast-acting WDRC. ADRO uses a set of fuzzy-logic rules to make gain changes to optimize audibility, comfort, protection against loud sound, and noise attenuation. The "hearing protection" gain rule acts instantaneously, whereas the audibility and comfort rules adjust the gain slowly, such that ADRO provides linear amplification most of the time.

 The goal of this study is to examine the physiological basis for the relative performance of linear amplification, WDRC, and ADRO. Sentences from the TIMIT Speech Database were processed by each algorithm. In the case of WDRC, both single-channel and multi-channel schemes with fast and slow dynamics were tested. Speech signals were presented at 52, 62, 74, and 82 dB SPL (sound pressure level) with various noise levels and types, to simulate real-life environments. The simulations first use an auditory-periphery model to generate a "neurogram" of the auditory nerve's representation of the test speech material. The spectral and temporal modulations in the
neurogram are then analyzed by a model of cortical speech processing. The effects of the
background noise, the presentation level, the hearing loss and the amplification scheme are evaluated by comparing the cortical model response for a given condition (the "test" response) to the cortical model response to the same TIMIT sentence presented in quiet at
65 dB SPL to the normal-hearing model (the "template" response). From the difference
between the test and template responses, a spectro-temporal modulation index (STMI) value is calculated. High STMI values predict good speech intelligibility, while low values predict poor intelligibility. Results show that ADRO is better at restoring the neural representation of speech than the other algorithms tested, even when the WDRC algorithms utilize slow time constants. In the case of no background noise, all the algorithms perform similarly well. However, when background noise is added, STMI values for higher SPLs drop notably for all the algorithms except for ADRO, which sustains a stable value throughout the range of SPLs test.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Sensitivity Analysis for Design Optimization of Metallic Microwave Structures with the Finite-Difference Frequency-Domain Method

contributor:
Nikolova, Natalia K.
Electrical and Computer Engineering

subject: sensitivity analysis, design optimization, metallic structures, finite-difference, frequency-domain method

abstract:
 This thesis contributes significantly towards the development of a robust algorithm for design sensitivity analysis and the optimization of microwave structures. Based on the frequency-domain finite-element method, the approach provides accurate sensitivity information using both 2-D and 3-D formulations. It also significantly accelerates the optimization process.

 The design sensitivity analysis method greatly influences the efficiency and accuracy of gradient-based optimization by providing the response gradient
(response Jacobians) for the whole range of parameter values. However, common commercial electromagnetic simulators provide only specific engineering responses, such as Z- or S-parameters. No sensitivity information is made available for further exploration of the design-parameter space. It is common to compute the design sensitivities from the response themselves using finite-difference or higher-order approximations at the response level. Consequently, for each design parameter of interest, at least one additional full-wave analysis is performed. However, when the number of design parameters becomes large, the
simulation time becomes prohibitive for electromagnetic design procedures.

 The self-adjoint sensitivity analysis (SASA) is so far the most efficient way to extract the sensitivity information for the network parameters with the finite-element method. As an improvement of the adjoint-variable method (AVM), it eliminates the additional (adjoint) system analyses. With one single full-wave analysis, the sensitivities with respect to all design parameters are computed. This significantly improves the efficiency of the sensitivity computations. Through our proposed method, the finite-difference frequency-domain self-adjoint sensitivity analysis (FDFD-SASA), the process is further improved by eliminating the need for exporting the system matrix, thus improving both compatibility and computation time. The only requirement for integrating the sensitivity solver with the commercial EM simulators is the ability to access the field solution at the user-defined grid points. The sensitivity information is obtained by simple manipulation of the field solution as a post-process and hence, it adds little or no overhead to the simulation time.

 We explore the feasibility of implementing our newly proposed method using field solutions from a frequency-domain commercial solver HFSS v 11. We confirm the accuracy of the FDFD-SASA for shape parameters of metallic structures. Both 2-D and 3-D examples are presented, where the reference results are provided through the traditional finite-difference approximations. Also, the efficiency of the FDFD-SASA is validated by a filter design example, exploiting
gradient-based optimization algorithm.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Dilatation, Flame Strain, Displacement Speed and Curvature in Turbulent Premixed Flames Using Direct Numerical Simulation

contributor:
Tullis, S.
Mechanical Engineering

subject:
dilatation
turbulent flames

abstract:
The relationship between dilatation, displacement speed, flame tangential strain rate and flame normal velocity gradient for a premixed turbulent flame in a corrugated/wrinkled flame regime is analyzed. The decomposition of dilatation into the flame tangential and normal strains and their relationship with curvature is studied. Three-dimensional, fully compressible direct numerical simulations (DNS) of premixed flames in a cube have been performed using a uniform 256^3 grid. For the turbulent case, decaying isotropic homogeneous turbulent velocity field is considered with an initial turbulence spectrum imposed. Simple single-step chemistry with an Arrhenius reaction rate is used. This simplification is valid as the flame considered is in the corrugated/wrinkled regime where the flame thickness is smaller than the smallest scales of turbulence. A single laminar flame is initially inserted into the turbulent field. A strongly linear relationship between dilatation and curvature has been seen which is due to the high correlation of displacement speed with curvature. The correlation between tangential strain rate and curvature is shown to be negative with a breakdown due to the curvature reaching the scale of the flame thickness at the cusps. To isolate the effect of heat release and turbulence, cases of a laminar sinusoidal wrinkled flame and a turbulent
𝛕=0 flame have been carried out. For a laminar sinusoidal wrinkled flame, a negative correlation between a^𝛕 and curvature was seen. This contradicts previous hypotheses (Haworth and Poinsot, 1992) (Chakraborty and Cant, 2004) where the negative correlation between a^𝛕 and curvature was explained to be due to different turbulence levels in front and behind the flame. Turbulence and alignment of flame surface with expansive tangential strains is shown to be responsible for the scatter seen in a^n and a^𝛕 relationships with curvature. Changing the peak reaction location towards the front of the flame did not change the trend in the plots of dilatation, tangential and normal strain rates versus curvature, confirming that dilatation relationship with curvature in particular is not due to any curvature distortion of the flame interior. However, it did thicken the flame and reduce the dilatation (and consequently its components, an and at) plot versus curvature and the magnitude of their curvature dependence.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Nature of Mobile Work and the Needs for Mobile Work Technology Support: A Task-Technology Fit Perspective

contributor:
Yuan, Yufei
Business Administration

subject:
mobile work
technology support

abstract: The rapid growth in the use of wireless communication and portable devices in recent years has created a great potential for a variety of mobile work technology support. However, we still lack the theories to explore the nature of mobile work, examine the needs for mobile work support, and identify the appropriate mobile technologies for various kinds of mobile work. This study is an attempt to meet the challenge. A mobile task model is proposed in this study which includes four dimensions: task complexity, task interdependence, time criticality, and location sensitivity. New instruments are developed to measure the constructs of time criticality and location sensitivity. Six typical mobile work support functions are examined: mobile communication, mobile information searching, mobile transaction processing, location related service, mobile job dispatching and mobile office. In light of contingency theory and attitude/behavioral theory, a research model is proposed to identify the ideal fit between task characteristics and typical mobile work support functions. Based on empirical data from real mobile workers, the nature of mobile work and the differences in mobile work between mobile knowledge workers and field workers are analysed. New instruments for the time and location related constructs are validated through the empirical data. The differences in perceived usefulness of the typical mobile work support functions between mobile knowledge workers and field workers are presented, as well as those of the current usage and intention to use. Finally, the ideal fit is identified on the basis of the empirical data. This study contributes both to theory and practice. The establishment of a mobile task model, including the development of new instruments for time and location constructs, provides a foundation for future mobile business research. The identification of the ideal fit between task characteristics and mobile technology functions, based on contingency theory and attitude/behavioral theory, extends and enriches mobile business research. The results of the study can provide guidance and recommendations on how to strategically plan and implement suitable mobile applications, and to identify opportunities for the development of appropriate technological solutions for mobile work support.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Ionoregulatory Physiology of the African Lungfish, Protopterus dolloi and Protopterus annectens

contributor:
Wood, C.M.
Biology

subject: teresstial vertebrates, water-dependent fish, African Lungfish, ionoregulatory physiology, freshwater teleosts, gill, kidneys

abstract:
 The origin of terrestrial vertebrates from water-dependent fish involved numerous
morphological and physiological modifications (Benton, 1990). Interest in the adaptive mechanisms involved in the transition from aquatic to terrestrial environments has led to
research involving lungfish. African lungfish are obligatory air breathers and have a primitive lung and characteristically underdeveloped gills compared to freshwater teleosts. The gills are thought to play an important role in CO2 excretion and possibly in water and ionic exchange while in aquatic conditions. At present, little is known about the basic ionoregulatory physiology of lungfishes; the aim of this thesis was to describe the basic principles of ion and water balance in two species of African lungfish, Protopterus dolloi and Protopterus annectens. Patterns and rates are very similar in the two species, apart from differences in water handling at the kidney. In aquatic conditions, plasma ion (Na+, Cl-, Ca2+) levels are lower than in teleost fish. The major site of diffusive water exchange appears to be the gills. The skin is well vascularized and also serves as site of water exchange, and likely Cl- and Ca2+ uptake as well. However, water and ion exchange rates are lower than in freshwater teleosts, probably due to the reduced gill area, though glomerular filtration, urine flow rates (an index of osmotic permeability), and urinary ion excretion rates are comparable to those of teleosts. Water exchange rates increase immediately after feeding, likely associated with specific
dynamic action, and decrease with prolonged terrestrialization, likely due to disturbances in gill function. A budget analysis of ion balance indicates that both unidirectional uptake from the water and net uptake from the food (especially for Cl-) are important, whereas unidirectional efflux across the gills and/or skin is a larger route of ion loss than are feces or urine. Despite many physiological differences between freshwater teleosts and the African lungfish, water and ion balance are maintained in a broadly similar fashion and are achieved by compensating for the reduced gill area by ion acquisition via the skin and by greater ion reabsorption by the kidneys.

abstract: Thesis

abstract: Master of Science (MSc)


title: TACTILE NAVIGATION: AN ADDITIONAL PROCESSING CHANNEL FOR ENVIRONMENTS OF HIGH SENSORY LOAD

contributor:
Goldreich, Daniel
Psychology

subject:
Tactile Navigation
Tactile information
tactile channel
multiple resource theory
audio GPS
sensory load

abstract: Persons with visual impairments often rely on navigational electronic aids, which typically employ speech commands for guidance through novel routes. However, navigational speech commands may interfere with the perception of acoustically rich environmental information, resulting in potentially detrimental effects. We investigated the sense of touch as a means to convey navigational commands instead. The somatotopic representation of the body surface within the central nervous system makes spatial information intuitive to our skin, suggesting that the tactile channel should be equivalent to, if not better than, the auditory channel at processing directional commands. Additionally, based on Wickens’ Multiple resource theory, the tactile channel should mitigate the sensory load in the auditory channel in travelers with visual impairments. We tested the ability of blind users to process directional commands conveyed via a tactile navigational belt. 14 blind participants were tested with the tactile belt under conditions of either low or high acoustic sensory load, simulating different outdoor environments. For comparison, the same participants were tested also with a conventional auditory device.  Consistent with previous studies, we found navigation with the tactile belt to be less efficient than navigation with the auditory aid in the absence of environmental sounds. However, we found also – for the first time, to our knowledge – that tactile performance was less compromised under conditions of high acoustic sensory load. These results will help to inform the further investigation and development of tactile displays to benefit blind travelers.

abstract: Thesis

abstract: Master of Science (MSc)


title: Kinematics and Wear of Novel EDM Tooling

subject: kinematics EDM

abstract:
Over the last few decades Electrical Discharge Machining (EDM) has become a well established technology that is used throughout the manufacturing sector. In this time, changes in generator technology as well as tool design have brought about a many fold increase in EDM machining rates, particularly in Wire EDM. Yet in Ram-EDM issues with flushing of the inter-electrode gap hinders such improvements to material removal rates. In order to improve the removal rates in Ram-EDM new flushing methodologies are necessary.
With this in mind an investigation into novel tooling kinematics, aimed at enhancing inter-electrode gap flushing is presented. Theses novel kinematics are inspired by the Reuleaux Triangle and its ability to machine near sharp comers. This concept is expanded upon in 1)rder to generate tool kinematics, which can machine regular as well as irregular polygons with sharp comers using rotating tools. The curvilinear tooling geometries described in this work are moved along complex orbits which necessitate a 4-axis CNC EDM machining center. Furthermore the slow axis travel speeds on current EDM machining centers presents an obstacle to properly implementing a rapid orbit meant to generating flushing. This problem is obviated in new ED-milling machines, but in the absence of such a machine alternative testing methods were investigated to prove the concept. It is shown that the Reuleaux Triangle inspired tooling machines at constant speed independent of depth, unlike traditional Ram-EDM tools that slow down as greater depths are reached. Thus tr e novel tooling geometries are capable of many fold improvements of machining rates. Ur fortunately these improved removal rates are achieved at the expense of localized tool wear. The novel tooling kinematics result in uneven tool wear patterns that cannot be modded using currently available techniques, thus a new simulation technique is presented. This technique reduces the 3D wear experienced by tools to allow a 2D simulation thereof. A number of examples area shown in order to validate this simulation technique. Due to uneven wear and poor machining rates at low pulse energies, the novel tooling kinematics are deemed unsuitable for finishing operations, but they excel in roughing regimes. It is therefore suggested that the novel tooling be used for the bulk material removal and a conventional Ram-EDM form tool be used to finish the cavity.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: An ALMA Archival Study of the Clump Mass Function in the Large Magellanic Cloud

contributor:
Wilson, Christine
Physics and Astronomy

subject:
Astronomy
Interstellar Medium
Large Magellanic Cloud
Mass Function

abstract: This thesis presents 1.3 mm and 3.1 mm continuum maps of seven star forming regions within the Large Magellanic Cloud (LMC) as observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). The data were taken as part of six projects retrieved from the ALMA public archive plus one project observed specifically for this work. We developed a technique to combine Band 3 and Band 6 maps to estimate dust-only emission corrected for free-free emission contamination. We also present an automated \texttt{clean} masking script, with a listing of the code, which we adapted and used for all of the imaging in this thesis. From these observations we identify 32 molecular clumps in the LMC and estimate their total mass from their dust emission. We derive a cumulative clump mass function ($N(\geq M) \propto M^{\alpha+1}$) and fit it with a double power law to find $\alpha_{\mathrm{low}} = -1.76^{+0.07}_{-0.1}$, $\alpha_{\mathrm{high}} = -3.3^{+0.3}_{-0.6}$, and a break mass of $2500^{+700}_{-300}$ M$_{\odot}$. Comparing to the clump mass function derived by Indebetouw et al. (2013) from carbon monoxide spectral line emission for 30 Doradus-10 shows a consistent mass range of clumps between 205 $\mathrm{M}_{\odot}$ and 5740 $\mathrm{M}_{\odot}$ as well as consistency between their single power law fit and our low mass power law index. Also comparing to core and clump mass functions from several star forming regions in the Milky Way we find consistency between most of their high mass indices and our low mass index, which is where the clump mass ranges overlap.

abstract: Thesis

abstract: Master of Science (MSc)


title: NOVEL THERAPEUTIC FOR RESPIRATORY SYNCYTIAL VIRUS

contributor: Medical Sciences (Molecular Virology and Immunology Program)

subject: Virology, RSV, peptide mimetic, P1-29, antiviral

abstract:
Background: Respiratory syncytial virus (RSV) is one of the leading causes of acute lower respiratory tract infection and childhood hospitalization worldwide. However, there are currently no vaccines or antivirals available to prevent or treat RSV infections. Of the 11 proteins encoded by RSV’s negative-sense single-stranded RNA genome, the nucleoprotein, phosphoprotein, and large polymerase interact through well characterized domains to form the RNA-dependent RNA polymerase complex. This polymerase complex is essential for viral replication and virulence, which makes it an excellent antiviral target. Previous studies have shown that the nucleoprotein-phosphoprotein interaction of the polymerase complex can be disrupted by synthetic peptides of the last 21 C-terminal (P220-241) or the first 29 N-terminal (P1-29) amino acids of the phosphoprotein.
Objective: The Mahony lab has also previously demonstrated that P220-241 conjugated to a maltose binding protein (MBP) and HIV-1 Tat cell penetrating peptide (CPP) could inhibit up to 90% of RSV A replication in vitro. However, the bacterial derived MBP is immunogenic. This study builds on these findings by developing and evaluating the efficacy of a P220-241 peptide mimetic conjugated to human thioredoxin (hTrx) carrier protein and a P1-29 peptide mimetic conjugated to MBP.
Methods and Results: Inverse PCR and In-Fusion® cloning was used to clone a hTrx-P220-241 plasmid, which was then expressed as a recombinant protein and purified by affinity chromatography for functional analysis. HTrx-P220-241 was shown to specifically interact with RSV nucleoprotein in a glutathione S-transferase (GST) pull down assays and it could successfully enter into LLC-MK2 cells. However, upon challenge with RSV A, LLC-MK2 cells that were incubated with increasing concentrations of hTrx-P220-241 did not inhibit RSV A replication when assessed by indirect immunofluorescence microscopy. The MBP-P1-29 construct did not exhibit any significant cytotoxicity in LLC-MK2 cells nor BEAS-2B cells. Upon challenge with RSV A, LLC-MK2 cells and BEAS-2B cells pre-treated with MBP-P1-29 demonstrated a dose-dependent inhibition of RSV replication in vitro, with a percent inhibition of infection of 80% and 60% respectively. Furthermore, MBP-P1-29 also reduced the release of infectious progeny virion by up to 74% in LLC-MK2 cells and 34% in BEAS-2B cells.
Conclusion: Phosphoprotein peptide mimetics targeting essential nucleoprotein-phosphoprotein interaction are a promising approach in the development of therapeutic treatments for RSV. In this study, a P220-241 peptide mimetic conjugated to a human thioredoxin scaffold protein was not able to inhibit RSV A replication while a P1-29 peptide attached to a maltose binding protein was effective in reducing RSV replication in vitro. Thus, further studies are required to evaluate a P1-29 peptide mimetic against different RSV A and B strains and to find an appropriate human carrier protein to attach it to.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Respiratory syncytial virus is a respiratory illness that is one of the leading causes of childhood hospitalization worldwide. RSV infects almost all infants at least once by the age of two. It can also repeatedly infect individuals throughout their lives, which puts the elderly and individuals with weak immune, cardiac or pulmonary systems at risk. There are also no approved vaccines or antiviral treatments available to prevent or combat a RSV infection, which highlights the pressing need for the development of new antiviral drugs. This thesis focuses on developing and evaluating the efficacy of two different antiviral peptides, which both target and disrupt the formation of the viral machinery required for the replication of the RSV genome.


title: 3-D Imaging of Root Architecture Using Multichannel GPR

title: Multichannel 3-D Ground-Penetrating Radar (GPR) Imaging of Tree Root Architecture for Biomass Estimation

contributor:
Boyce, Joseph
Earth Sciences

subject:
3-D multi channel GPR
dual polarization
tree roots
root detection

abstract:
Root biomass accounts for about 25% of the carbon storage in mid-latitude forests. Estimation of root biomass for carbon cycling studies requires either direct measurement by excavation of root systems, or remote measurement using ground penetrating radar (GPR) or other geophysical methods. This study evaluated the ability of a 2-GHz multi-channel GPR system (IDS Hi-BrigHT) to detect and map white pine roots in managed forest near Turkey Point, southern Ontario. The GPR system employed eight dual-polarized antenna pairs separated at 10 cm intervals. GPR data were acquired as overlapping swaths (2 cm line spacing, 0.4 cm inline) across a 25-m2 test site (TP74-R) containing a juvenile white pine tree. Radargrams were processed to full 3-D radar volumes for time slicing and interpretation of root architecture and comparison with the excavated root network.
Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found in the rooting zone at a depth of 5-40 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Root detection was strongly dependent on root orientation; large, coarse roots (>3-5 cm) were imaged as continuous root segments when oriented perpendicular to GPR profiles.  Roots intersecting GPR profiles at angles <30-45 degrees were either imaged incompletely or not detected on radargrams. The highest rate of root detection was achieved with horizontally polarized (HH) antennas (dipole axis parallel with the root structures). Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. Isosurface models provide a means for estimating the coarse root volume for large roots and could be employed in future work to monitor temporal changes in root biomass by repeat survey at the same measurement site.
Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found in the rooting zone at a depth of 5-40 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Many roots were not detected due to dependence of root reflection amplitude on root orientation. Roots oriented at >30-45 degrees to the survey swaths were imaged incompletely or not detected. Most large coarse roots (>5 cm diameter) were mapped as continuous structures when the root orientation was either parallel to, or perpendicular to the GPR transects. The highest rate of root detection was achieved with the horizontally polarized (HH) antennas, with the dipole axis perpendicular to the root structures. Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. The isosurface models provide a means for estimating the coarse volume and belowground biomass but further work is required to improve 3-D image resolution to allow detection of the entire root network. The method could be employed to measure the temporal changes in root biomass by conducting repeat surveys at the same measurement site.
Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found above a depth of 40 cm with the root zone being detected at a depth of10-15 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Many roots were not detected due to dependence of root reflection amplitude on root orientation. Roots oriented at >30-45 degrees to the survey swaths were imaged incompletely or not detected. Most large coarse roots (>5 cm diameter) were mapped as continuous structures when the root orientation was either parallel to, or perpendicular to the GPR transects. The highest rate of root detection was achieved with the horizontally polarized (HH) antennas, with the dipole axis perpendicular to the root structures. Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. The isosurface models provide a means for estimating the coarse volume and belowground biomass but further work is required to improve 3-D image resolution to allow detection of the entire root network.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
Forests play an important role in the global carbon cycle by removing carbon from the Earth’s atmosphere and storing it in tree tissues as biomass. Estimation of the amount of biomass and carbon stored in forests is critical to predictive climate change models, and increasingly employs remote sensing methods to detect both the above ground biomass (e.g. leaves, tree branches) and the belowground carbon in the tree root system. Measurement of the belowground biomass is most difficult, as it cannot be directly observed without destructive excavation of the tree root system.
This study investigated the application of new technology, multi-channel ground penetrating radar (GPR), for mapping tree root systems. The GPR system (IDS Hi-BrigHT) employs ‘swath mapping’ using high frequency pulsed radio waves and multiple transmitting and receiving antennas to produce detailed maps of roots structure. The GPR capabilities were evaluated at a test site at the Turkey Point Flux Station (TPFS) in southern Ontario. The root system of a juvenile white pine tree (20-30 cm diameter) was swath mapped over a 25-m2 area with a line spacing of 2 cm. The GPR data were processed to produce a 3-dimensional radar volume, which can be ‘sliced’ in various orientations to reveal the root structure. The time slice maps show that roots as small as 1-cm can be detected and roots larger than 3 cm in diameter can be mapped as continuous root segments.


title: A Spatial Analysis of Fish Habitats in Coastal Wetlands of the Laurentian Great Lakes

contributor:
Chow-Fraser, Patricia
Biology

subject:
fish habitats
coastal wetlands

abstract: The overall objective of this study was to provide a spatial pattern analysis offish distribution in the Great Lakes and to relate these patterns to shoreline features such as coastal wetlands, tributaries and substrate type. Very little is known regarding the distribution patterns of fish in the Great Lakes at the geographical scale of each lake basin. I first explored whether there were systematic patterns in distribution offish and coastal wetlands by looking at density maps of each and calculating nearest neighbor distances. I used three different classification schemes to sort the 139 fish taxa into functional categories to produce ecologically meaningful distribution maps. There were striking differences in the overall distribution pattern of nursery and spawning habitat in the five Great Lakes when data were compared for Jude and Pappas' classification taxocenes: open-water, intermediate and coastal. Overall, open-water species were the most abundant, and were also widely distributed throughout all five lakes. Coastal species were the least abundant and appeared to be restricted to the two lower lakes. The distribution pattern of coastal and intermediate taxa overlapped a great deal; both taxocenes made extensive use of the two lower lakes for spawning and nursery habitat during this synoptic survey, especially in western Lake Erie and eastern Lake Ontario. Fish distribution patterns sorted by thermal preference and by reproductive guild were compared with those sorted by taxocene. Results from a chi-square analysis indicated a high degree of overlap between thermal classes and taxocenes. There were also positive associations between many reproductive guilds and the three taxocenes, although these were not as strong as the previous comparison. I then examined spatial association between distributions of fish and coastal wetlands and other geomorphic features by testing the distribution offish along the shore of the Great Lakes and calculating the correlation between fish and coastal wetlands of Lake Ontario. A chi-square goodness-of-fit test indicated strong associations between the distribution offish and three shoreline classes: (wetland, sandy beach/dunes and bluff) and fish used coast~cl wetlands preferentially for spawning and nursery habitat at a basin-wide scale. Bivariate pattern analysis indicated that occurrences offish in L. Ontario were positively associated with both coastal wetlands and tributaries, although the relationship was considerably weaker for tributaries than for wetlands. Results from this study indicated that 1) Fish have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 2) Coastal wetlands have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 3) Spatial distribution offish and wetlands is positively associated; 4) The preferred utilization of coastal wetlands by majority of the Great Lakes fishes is consistent across geographic scales, from the site level to that of the entire Great Lakes basin.

abstract: Thesis

abstract: Master of Science (MSc)


title: Pneumatic Non-Contact Roughness Assessment of Moving Surfaces

contributor:
Koshy, Philip
Mechanical Engineering

subject: moving surfaces

abstract:
All machined surfaces inherently have roughness. The level of control of this
surface is dependeat on the specifications outlined for its intended use. In strictly
controlled situatiom, the monitoring and characterization of these surfaces becomes
increasingly important to ensure that each component conforms to specifications. For this
reason, the need for in-situ monitoring systems has increased in order to optimize
manufacturing time and minimize generated scrap for companies to remain competitive
in industry. Current in-situ roughness monitoring systems, such as optical methods, are
limited by the harsl: environments in which these systems are required to operate and the
requirement for highly reflective materials. Accordingly, the need to develop a more
robust system is required. The objective of this work was to develop and test a noncontact
surface roughness characterization system which can be implemented into a machining center in order to provide in-situ measurements where currently available methods are rendered inappropriate. Through the use of a pneumatic technique, a non-contact surface assessment tool has been developed and tested for use in a machining center. The development began
offline for characterization of surfaces created by different machining operations and was
then introduced in to a turning center for in-situ evaluation. The developed system is
capable of distinguishing surfaces created from different machining operations with the
same Ra values, characterize milled and turned surfaces down to R^a values of 0.8 μm that
are comparable with stylus measurements, impervious to external influences on the measurement process such as cutting fluid, capable of characterizing moving surfaces with surface speeds up to 100 m/min, provides surface characterization around the entire
workpiece instead of along a single line, and can be operated in-process to monitor the
entire workpiece or be used to make spot checks for important surface features.
The developed system is capable of providing a method for in-situ monitoring of machined surfaces where currently available techniques fall short. The limitations caused by the harsh environment in which these in-situ monitoring devices operate and the limitations of workpiece materials have been eliminated and the developed system has been proven to provide results comparable to stylus measurements that are the industrial standard.
This work is the basis for the development of a non-contact, in-situ surface roughness assessment tool. Limitations of the current device are also presented. Further research and development avenues are identified to expand the operating envelope of the developed pneumatic system.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The role of the p53 and nucleotide excision repair proteins in the base excision repair of methylene blue plus visible light induced DNA damage

subject: nucleotide excision repair proteins, methylene blue, oxidative damage,

abstract: The nucleotide excision repair pathway (NER) has been shown to efficiently remove bulky base lesions from the DNA, including those induced by solar light. It has been suggested that the NER pathway may be involved also in removing smaller oxidative base lesions from the DNA. Oxidative damage in the cell is caused by cellular aerobic respiration, with base damage to the nucleotides of the DNA being the most biologically relevant. One of the most common oxidative base lesions in the genome is the 7 ,8-dihydro-8-oxoguanine (8-oxoG). This lesion is pre-mutagenic since it can base pair with equal efficiency to the correct cytosine base, or the incorrect adenine base during DNA replication. Oxidative damage, including 8-oxoG, is repaired primarily by the base excision repair (BER) pathway, which is a multi-step, multi-protein pathway similar to NER. One key protein involved in both BER and NER is the p53 protein, which can act as a transcription factor and protein regulator to influence DNA repair. We have used a recombinant non-replicating human adenovirus, Ad5HCMVlacZ, which expresses the ~-galactosidase (~-gal) reporter gene, to examine the role of several NER proteins and the p53 protein in the BER of oxidative damage in human cells. Methylene blue (MB) acts as a photosenstizer, and after irradiation by visible light (VL) produces reactive oxygen species that cause 8-0xoG in the DNA. By infecting several normal, NER deficient and p53 deficient -tumor, primary and transformed fibroblast cell lines with a MB+VL-treated Ad5HCMVlacZ reporter construct, we were able to determine the host cell reactivation (HCR) of the oxidatively damaged reporter. Results indicate that the HCR of the MB+VL-treated reporter and the expression of p53 are enhanced by UVC pretreatment in normal human fibroblasts, suggesting that p53 may be involved in inducible BER. In addition, increased expression of p53 facilitated by pre-infection of normal cells with p53 expressing Ad5p53wt similarly enhanced HCR in the normal fibroblasts, giving further evidence that increased expression of p53 alone enhances BER. In contrast, although UVC pretreatment of p53 compromised cells resulted in enhanced HCR, the enhanced HCR did not correlate with enhanced p53 expression, suggesting that enhancement in BER can result from both p53 dependent and p53 independent mechanisms. We report also that HCR of the MB+VL-treated reporter gene was substantially reduced in SV40-transformed XP-C cells, with little or no reduction in SV40-transformed XPA, XPD, XPF, XPG and CSB cells, suggesting a role for the XPC protein in the BER ofMB+VL-induced DNA damage. In particular, the XPC protein appears to be involved in both the constitutive and inducible aspects of BER, as the HCR of the MB + VL-treated reporter was reduced in 3 UVC pretreated as well as untreated XP-C primary human fibroblast strains. In addition, pre-infection of cells with Ad5p53wt, resulted in an enhanced HCR of normal but not XP-C deficient fibroblasts consistent with a p53 dependent involvement of the XPC protein in BER of MB+VL-treated DNA. Additional studies were also conducted to determine the cell sensitivity of normal and NER deficient SV40-transformed cell lines to MB and MB+VL. The results show that MB alone and MC+VL are toxic to cells, and that cells deficient in NER are not more sensitive to MC or MB+VL compared to NER proficient normal cells. In fact, the NER deficient cell lines were more resistant to MB alone compared to NER proficient normal cells. In particular, although the SV40- transformed XP-C cell line showed a significant reduction in HCR of the MB-Vl-treated reporter gene, suggesting a deficiency in the repair of MB+VL-induced DNA damage, the SV40-transformed XP-C cells were not more sensitive to MB or MB+VL. This suggests that the toxicity of human cells to MB and MB+VL results primarily from damage to cellular components other than DNA such as membrane structures including the mitochondria and lysozomes as has been reported for other photosensitizers.

abstract: Thesis

abstract: Master of Science (MSc)


title: Markerless Human Tracking for Industrial Environments

contributor:
Bone, Gary M.
Mechanical Engineering

subject: human industrial markerless

abstract: This thesis presents a markerless multiple-camera vision-based 30 human tracking method for industrial environments. The method can track humans in the vicinity of moving robots without using skin color cues or articulated human models. It is robust to self-occlusions and to partial occlusions caused by the robot. Foreground pixels corresponding to humans are found by background subtraction. A convex polyhedron enclosing the human(s) is generated online by bounding the foreground pixels in 30 space. Experimental results are included for a single person and multiple persons walking near a moving PUMA robot in a cluttered environment. Reliable tracking at 11.2Hz is demonstrated using four cameras and a Pentium 4 PC. The tracking data may be used for online robot collision avoidance.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Fluidelastic Instability of Finned Tube Bundles in Normal and Parallel Triangular Arrays

contributor:
Weaver, D. S.
Mechanical Engineering

subject:
finned tube
triangular arrays

abstract: Experimental study was conducted to investigate fluidelastic instability in finned tube bundles with normal and parallel triangular arrays. Three arrays of each geometry type were studied experimentally: two arrays with serrated, helically wound finned tubes of different fin densities, and a bare tube array with the same base diameter as the finned tubes. The finned tubes under consideration were commercial finned tubes typically used in the fossil and process industries. For the purpose of the present investigation, the concept of "effective diameter" of a finned tube, as used to predict the vortex shedding, was used to compare the finned tube results with the existing bare tube world data and some theoretical predictions for fluidelastic instability. The finned tube arrays in this study have the same tube pitch and have been scaled to have the same mass ratio and tuned to have the same natural frequency. A low speed wind tunnel, Betz micro manometer and HP 35670a dynamic signal analyzer were employed to conduct the experiments. Experimental results for the triangular arrays show that the fin's structure strongly influences the fluidelastic stability of finned tube bundles and the fin pitch is demonstrated to reduce the difference in the fluidelastic instability between the tube arrangements as the fin density increases. The results also suggest that there might be an optimum fin pitch value at which the threshold reduced velocity for a finned tube array is much higher than the one for its corresponding bare tube array, due to the influence of fin geometry. In the appendix, an analytical model produces a new correlation of critical reduced velocity against mass damping parameter to predict the fluidelastic instability of tube bundles. Its predictions are in reasonable agreement with the experimental data. Since negative damping is one of the mechanisms of fluidelastic instability of a tube array, "Lift effect" was applied to explain the negative damping in an inviscid flow. An experiment is suggested to test the relationship between the pitch flow velocity and a tube velocity dependent "lift effect". Accordingly, two duct structure designs are suggested which may alleviate the negative damping by using the energy of oncoming flow to reduce the "lift effect" on the tubes.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Joint Design of Transceivers for Multiple Access Channels using MMSE Decision Feedback Detection

contributor:
Wong, Kon Max
Zhang, Jian-Kang
Electrical and Computer Engineering

subject: MMSE Transceivers

abstract: In this thesis, we consider the joint design of transceivers for a multiple access Multiple Input and Multiple Output (MIMO) system having Inter-Symbol Interference (ISI) channels. The system we consider is equipped with the Minimum Mean Square Error (MMSE) Decision-Feedback (DF) detector. Traditionally, transmitter designs for this system have been based on constraints of either the transmission power or the signal-to-interference-and-noise ratio (SINR) for each user. Here, we explore a novel perspective and examine a transceiver design which is under a fixed sum Gaussian mutual information constraint and minimizes the arithmetic mean square error of the MMSE-decision feedback detection. For this optimization problem, a closed-form solution is obtained. We prove that the optimal solution is achieved if and only if the sum mutual information is uniformly distributed over each individual user per the number of its active subchannels; i.e., user mutual information uniform distribution. Meanwhile, the Gaussian mutual information of the current user under perfect feedback for all the previous users is uniformly distributed over each individual symbol within the block signal of the user; i.e., symbol mutual information uniform distribution. The user mutual information uniform distribution is attained by successively solving a series of inverse (dual) problems of maximizing single user throughput, while the symbol mutual information uniform distribution is maintained by using the equal diagonal QRS decomposition. We also show that such uniform decomposition, in addition to minimizing the arithmetic MSE of MMSE-decision feedback detection, also has another two optimality properties: (a) Both the optimal user-detection order and symbol-detection order are natural orders in terms of signal to interference and noise ratios. (b) The free-distance for the Maximum Likelihood (ML) detector has an asymptotic behavior when the sum Gaussian mutual information tends to large.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Analysis of Trauma Patterns and Post-Traumatic Time Interval in a Late Romano-British and Spanish Context

contributor:
Brickley, Megan
Anthropology

subject:
Fractures
Trauma Patterns
Injury Recidivism
Paleopathology
Bioarchaeology
Roman Empire

abstract:
Fractures, one of the most common findings in paleopathology, can reveal information about behaviour and social identity in the past. A new methodology for assessing the healing stages of fractures has recently been proposed, which could allow for additional data to be gathered from the study of fractures. Trauma, post-traumatic time interval, and injury recidivism were studied in five late Roman (c. 3rd – 4th centuries AD) British and Spanish skeletal samples. The aims of this thesis are: 1) record fractures and their healing stage using new post-traumatic time interval estimation methods; 2) determine how trauma profiles vary in the Romano-British and Spanish samples; 3) employ biocultural and life course approaches in the analysis of the results to reveal information about the culture, social identities, and environmental circumstances in the two Roman provinces under study.
The remains of 214 adults from two Romano-British and three Romano-Spanish sites were examined for the presence of long bone and rib fractures. Fracture data was analyzed by age, sex, site, bone element, and fracture type to build a profile of trauma at each of the sites. In addition, cases of multiple injury were assessed using new post-traumatic time interval methods in order to discern cases of injury recidivism.
A total of 44 individuals were identified as having 89 fractures across all the skeletal samples. Sixteen individuals had multiple fractures, eight of which were determined to have fractures of different ages using methods for determining post-traumatic time interval. Males and females had similar rates of fractures and multiple injuries. Fractures peaked among economically active young and middle-aged adults. A number of differences between the Romano-British and Spanish sample were observed with regards to trauma patterns and fracture prevalence.
The results of this research contribute to our understandings of trauma profiles and injury recidivism in Roman populations, and provide the first comprehensive trauma study of a Romano-Spanish skeletal sample.

abstract: Thesis

abstract: Master of Arts (MA)


title: An Improved Stochastic Hodgkin-Huxley Based Model of a Node of Ranvier for Cochlear Implant Stimulation

contributor:
Bruce, Ian
Biomedical Engineering

subject:
Hodgkin-Huxley
Cochlear Implant
Ranvier

abstract:
Cochlear implants (CIs) are prosthetic devices used to partially restore hearing for profound
and severely deaf individuals. CIs convert sounds into electrical pulses which stimulate
the auditory nerve fibers. An accurate model of auditory nerve fibers (ANFs) would
help in improving the functionality of CIs. Previous studies have shown that the original
Hodgkin-Huxley (1952) model (with kinetics adjusted for mammalian body temperature)
may be better at describing nodes of Ranvier in ANFs than models for other mammalian
axon types. However, the Hodgkin-Huxley model is still unable to explain a number of
phenomena observed in auditory nerve responses to CI stimulation, such as short-term and
long-term adaptation, the time-course of relative refractoriness, and stimulus-dependent
random fluctuations in membrane threshold. Recent physiological investigations of spiral
ganglion cells have shown the presence of a number of ion channel types not considered
in the previous modelling studies, including low-threshold potassium (𝐼^KLT) channels and
hyperpolarization-activated cation (𝐼^h) channels. In this thesis, inclusion of these ion channel types in a stochastic Hodgkin-Huxley model is investigated. Four versions of the model are formed and compared: that is, the standard Hodgkin-Huxley model, the standard model with /h only added, the standard model with 𝐼^KLT only added, and finally, the standard model with both h and 𝐼^KLT added. Two group of responses are explored: i) single-pulse responses and ii) pules-train responses. For the single pulse responses, a charge-balanced biphasic stimulus pulse is used. The effect of varying the pulse-width and the interphase gap is investigated for both leading phase polarities. Results are compared to responses for single monophasic stimulus pulses in some cases. Pulse-train responses are investigated for charge-balanced depolarizing-phase leading biphasic pulses at rates of 200, 800, and 2000 pulse/s. Results from single-pulse responses show an increase in spike threshold when one or both of these channel types are included. The addition of 𝐼^KLT increases random threshold fluctuations in the stochastic model, particularly for longer pulse widths. For pulse-train responses, rapid adaptation in spike rate may be resulting from 𝐼^KLT whereas 𝐼^h produces slower "short-term" adaptation. Thus, the simulation results suggest that including 𝐼^KLT
and/or 𝐼^h in a Hodgkin-Huxley model improves the accuracy of the model in describing
auditory nerve fiber responses during cochlear implant stimulation.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Convection, Diffusion, Thermophoresis and Electric Field Effects on Diesel Soot Deposition in a Cooled Exhaust Channel

contributor:
Berezin, A.
Chang, J.

subject:
convection
diffusion
thermophoresis
soot deposition

abstract:
New demands and tighter government legislations on greenhouse gases and pollutants, especially for those produced by diesel engines, there has been much focus on developing more efficient diesel engine designs and pollution control devices. There are several pollution control devices currently being implemented in diesel engines such as, diesel particulate filters, selective reduction catalyst, electrostatic filters, exhaust gas recirculation systems, etc. Diesel particulate matter is of particular importance especially when deposited because of its corrosive and thermal insulating nature. There are many complex mechanisms involved in fine particle deposition. This study will focus on the main deposition mechanisms such as
convection, diffusion, thermophoresis and electric field effects. The objective of this study was to evaluate experimentally the mechanisms of diesel soot deposition in a rectangular (RWCS) and cylindrical (CWCS) wall cooled sections to evaluate thermophoretic effects. In additional, the coaxial cylindrical wall cooled section with additional with coaxial wire electrode was used to study applied electric field effect (CCWCSE) on soot deposition. A non-destructive Real-Time Neutron Radiography technique was used to evaluate the soot deposition thickness profiles inside the cooled sections. The experiments were conducted using diesel engine exhaust from a single cylinder diesel engine operated at fixed 2.4kW, at a exhaust gas mass flow rate of 20 kg/hr with exposure times ranging 0 to 3hrs, coolant temperatures from 20 to 40°C and exhaust gas temperatures from 250 and 270°C. The resulting Reynolds Number based on the mass flow rate per cross-sectional area times the hydraulic diameter was 6300 for the RWCS and 9000 for the CWCS and CCWCSE. The results show that for the RWCS, the soot deposition pattern qualitatively matched the cooling water channel outer wall surface
temperature profile along with thicker deposition at the entrance region due to convection effects. For the ewes, the deposition was more uniformly distributed throughout the device. It was observed for both devices that as the mean soot deposition thickness increases with increasing exhaust gas exposure time and decreasing wall cooling temperature. Finally the experimental results for the CCWCSE shows that the soot deposition was enhanced by a positive or negative applied electric field.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Understanding Bike Share Usage: An Investigation of SoBi (Social Bicycles) Hamilton

contributor:
Scott, Darren
Geography and Earth Sciences

subject:
bike share
active travel
travel demand
cycling

abstract:
This thesis examines factors that influence the daily number of trip departures and
arrivals at over 100 hubs comprising Hamilton, Ontario’s (Canada) bike share program
– SoBi (Social Bicycles) Hamilton. SoBi operates all year, and during its first year of
operation (April 1, 2015 to March 31, 2016), over 200,000 trips were generated on SoBi
bikes. The study utilizes data from SoBi Hamilton, the 2011 Canadian Census, the 2011
Transportation Tomorrow Survey, Environment Canada, and Hamilton’s Open Source
Data initiative. From these master files, daily trips, meteorological data, temporal
variables, socio-demographic and built environment attributes were obtained to generate
a comprehensive suite of explanatory variables to explain the daily trips at each hub. A
multilevel regression approach was used to understand the associations between bike
share usage at each hub and each suite of explanatory variables at two temporal scales:
total daily trips at hubs and total daily trips across four time periods of the day. Findings
demonstrate that weather and temporal attributes play a significant role in trip departures
and arrivals. In addition, hub attributes vary in significance throughout different times of
the day for trip departures and arrivals. Overall, the methodology and findings allow us
to identify factors that increase SoBi usage, which can also benefit city planners and
engineers who are implementing a bike share system with the goal of maximizing bike
share activity in urban centers.

abstract: Thesis

abstract: Master of Science (MSc)


title: Determining Effective Lifetime of Minority Carriers in Silicon Through Modulated Free Carrier Absorption

contributor:
Kleiman, Rafael
Engineering Physics

subject: Free Carrier Absorption

abstract:
The minority carrier lifetime is a valuable parameter for determining the electrical properties of semiconductors. It is particularly useful in the fabrication of solar cells as minority carrier lifetime is directly related to device efficiency. Pump-probe techniques, in which a pump laser of photon energy above the bandgap energy of the material is used to excite free carrier populations while a sub-bandgap probe laser is used to monitor the change in excess carrier density have been demonstrated to be an effective, non-contact, method to measure the minority carrier lifetime, particularly well-suited for use as an in-line measurement apparatus for the solar cell manufacturing processes
 	In this thesis a non-contact, optical, pump-probe method has been used to determine the minority carrier lifetime of float zone and Czochralski grown <100> silicon samples through measurements of modulated free carrier absorption. The equivalence between measurements performed using the transmitted part of the probe beam and those made with the reflected part have been demonstrated on bare silicon wafers, as well as measurement of effective minority carrier lifetime of a completed solar cell, demonstrating the ability of this technique to measure the effective minority carrier lifetime at any stage of the solar cell manufacturing process.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Clinching of AA7075 Aluminum Sheets

contributor:
Mukesh, Jain
Mechanical Engineering

subject: Die-less clinching, Joining by forming, AA7075 aluminum, temper, material flow

abstract:
Weight reduction, increased fuel economy, and increased safety of structures in transportation applications has led to much interest in lightweight higher strength structural aluminum alloys. Suitable joining techniques to create such structures with aluminum sheets are required. Generally, similar and dissimilar sheet metals can be joined by adhesive bonding, welding, and mechanical fastening. Difficulty of welding and long processing times for adhesive bonding make mechanical fastening a process of much interest for joining of high strength aluminum sheets.
	Among the different mechanical fastening techniques available in manufacturing, clinching is a common method of joining by forming in which a punch and die are used to form a geometrical interlock. However, the process introduces surface steps on both sides of the joined sheets where one side consists of a protrusion and the other a pit. Also, clinch joining, a well-accepted and widely used process for joining ductile sheet metals, is more challenging for high strength lower ductility aluminum sheets such as AA7075.
	The current work aims at studying clinch-ability of high strength lower ductility AA7075 aluminum sheets of different tempers by conventional as well as a new clinching technique called "die-less" clinching. A new tooling was designed in order to conduct die-less clinches. The results showed that room temperature clinching is possible for the softer tempers namely solution treated and annealed states. However, the peak aged sheets failed to form a successful joint. A novel electrical resistance heating technique (ERH) to provide ductility to the joined sheets was used to obtain die-less clinched joints in AA7075-T6. ERH technique provides a large range of heating temperatures from room temperature to 270°C for a current duration of 3 sec. The AA7075-T6 sheets showed a superior joining by using ERH. The joint showed a metallurgical locking mechanism in addition to the commonly available form locking mechanism.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Clinching is a common method of joining sheet metals by forming. A punch and die are used to form a permanent geometrical interlock. However, the process introduces surface steps on both sides of the joined sheets where one side consists of a protrusion and the other a pit. Clinch joining is a well-accepted and widely used process for joining ductile sheet metals. Joining of high strength lower ductility aluminum sheets such as AA7075 is more challenging.
	The current work aims at joining AA7075 aluminum sheets of different tempers by clinching using the conventional method as well as a new clinching technique called "die-less" clinching. The study includes a new tooling design in order to conduct die-less clinches. Also, a novel electrical resistance heating technique (ERH) to provide ductility to the joined sheets was used to obtain die-less clinched joints in the peak aged AA7075-T6. ERH technique provides a large range of heating temperatures from room temperature to 270°C for a current duration of 3 sec. The AA7075-T6 sheets showed a superior joining by using ERH.


title: A History and Bibliography of George Herbert Editions

contributor:
Hammond, A.
English

subject:
Bibliography
George Herbert

abstract:
A descriptive bibliography of the numerous editions together with their later issues of George Herbert's writings. The list includes separate sections of both relevant manuscripts and also ghost editions. Selections are not included in the bibliography, but the more significant ones are noted in the accompanying essay on the history of George Herbert publications. The essay traces the trends which influence both publishers and their readership over the years 1612-1993, and though the focus is on George Herbert materials, the discussion is applicable to any study of publishing history. It argues that the nineteenth-century revival of interest in Herbert at its most prominent in the Victorian period was primarily a result of a devotionalism which favoured traditional ways. Yet, it is hard to separate this devotionalism from the
bourgeoning antiquarianism of the period. Similarly, those at the head of the
revival of interest in Herbert were literary people: S. T. Coleridge, Ralph
Waldo Emerson, John Keble and the Tractarians, The Pre-Raphaelites, George
Macdonald, and A. B. Grosart. As a result the revival represented a
remarkably comprehensive interest in Herbert's works. By way of contrast, in
the twentieth century the scholarly interest in Herbert appears to have
detached itself from a devotional involvement, and as the century draws to a
close this approach fostered eagerly by the universities brings with it the idea
that Herbert's poetry is inaccessible without an expert's instruction. Thus, at a
time when there is an extraordinary flowering of books about George Herbert,
we are beginning to see the return of Herbert to obscurity, an obscurity in practice which exceeds that which he suffered in the eighteenth century. The essay also considers the variety of ornamentation employed in Herbert editions, particularly the treatments of the shape poems "The Altar" and "Easter Wings", but also the use of plates and illustrations within the text. The bibliography itself includes details of trade bindings, original prices, numbers printed, and printers' and publishers' full addresses wherever possible. There are a number of uses for this bibliography beyond its immediate purpose. Anyone interested in the history of a printing or publishing house
should find helpful data, for instance. Bibliographers who are faced with undated issues or editions of a certain author may find a parallel item in this list which has an assigned date. It is hoped, too, that other bibliographers who are investigating Herbert publications will find this a source of data. The most important purpose of the bibliography, though, is to fill a present gap in Herbert studies, namely the need for a study of the publishing history of Herbert's writings.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)