1544981 |
Reliability and maintenance for interrelated systemsArmstrong, Michael John 11 1900 (has links)
In this paper we consider three topics in reliability and maintenance. Their
common feature is the explicit consideration of interdependence, either amongst
components within a machine, amongst stages in a logistics chain, or amongst machines
sharing maintenance facilities.
Chapter 1 examines measures of the contribution of a component towards a
system's reliability; these measures include structural importance, marginal reliability
importance, joint reliability importance, and link importance. We review these different
measures and examine how they relate to each other. We show that some structural
results previously derived for independent components continue to hold for associated
components. We then propose extensions to each importance measure to cover
components which have two failure modes rather than the conventional one, and show
that these extensions largely retain the properties of the original definitions.
Chapter 2 examines a system containing one machine subject to random failure, for
which we wish to determine a maintenance policy and a spare ordering policy. We
consider the solvability and desirability of jointly optimizing these two traditionally
separate policies. We discuss why the general form of the problem is intractable and show
how it might be approached using bounds and heuristic policies; more importantly, we
examine several special cases which are more tractable. Particular attention is paid to
systems which contain only one spare at a time; we show that these systems have some
convexity properties which facilitate cost minimization. We subsequently consider
systems which allow more than one spare, but make use of other restrictions or
assumptions to simplify analysis.
Chapter 3 examines how to coordinate maintenance for machines sharing repair
facilities, a task which is commonly called the machine repairman problem. Existing
studies of this problem make the restrictive assumption that repairs are performed only
after machine failure; our work extends the machine repairman model by allowing
preventive repair. We derive analytical results for a single critical age repair policy, and
then use numerical studies to investigate other heuristic policies which can improve the
system's cost effectiveness. / Business, Sauder School of / Graduate
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1544982 |
Mathematical modelling of the microstructure and texture changes during hot tandem rolling of AA5182 and AA5052 aluminum alloysWells, Mary A. 05 1900 (has links)
A mathematical model to predict the through-thickness microstructure and texture
changes during hot tandem rolling has been developed for two commercially significant
aluminum alloys - AA5182 and AA5052. The model includes a plasticity component to
model the temperature and deformation during rolling as well as an interpass component to
model the microstructure, texture and temperature changes which occur in the strip between
the rolling passes.
The plasticity model was developed using a commercial finite element package
DEFORM - a 2-D transient Lagrangian model which couples the thermal and deformation
phenomena which occur during strip rolling and is able to predict the temperature, strain rate
and strain distribution in the strip at any position in the roll bite.
The interstand model includes semi-empirical equations describing the microstructure
(percent recrystallization and recrystallized grain size) and texture changes occurring in the
strip between the rolling passes. The interstand model also includes a temperature module to
predict the through-thickness temperature distribution in the strip based on the one-dimensional
heat conduction equation which is solved by a finite difference method.
The semi-empirical equations used in the interstand model were developed using
experimental data for the two alloys. The experimental programme was carried out at Alcan
International's Banbury and Kingston Laboratories, as well as at the Atomic Energy of
Canada Limited Chalk River Laboratories. The experimental programme involved plane
strain compression testing industrial rolled samples of AA5182 and AA5052 aluminum
alloys based on a test matrix which covered similar temperature, strain and strain rate
conditions as those seen in industrial hot tandem rolling. The samples were given a single
deformation and then quenched immediately to preserve the as-deformed structure. The
samples were then heat-treated in a salt bath for various lengths of time and the percent
recrystallization, recrystallized grain size and texture changes during recrystallization were
measured. A temperature compensated time parameter was used to convert the isothermal
recrystallization and texture kinetics to non-isothermal applications.
Validation of the model using industrial data and samples indicated that it gave
reasonable predictions for the temperature, grain size and volume fraction of some of the
deformation texture components after recrystallization was completed. However, the model
tended to over-estimate the mill loads in the last stands for both the AA5182 and AA5052
alloys and tended to underestimate the amount of cube and S texture in the recrystallized
strip.
A sensitivity analysis of the process parameters indicated that both the microstructure
and texture were most sensitive to the rolling temperature. Indicating the need for good
control of temperature during rolling operations as well as accurate temperature predictions
for process modelling activities. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate
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1544983 |
Development of a low background environment for the cryogenic dark matter searchDa Silva, Angela Jane 05 1900 (has links)
A major problem currently facing astrophysics and cosmology is the question of dark
matter. Although there is little doubt about the existence of dark matter, there is considerable
uncertainty about the abundance and nature of this matter. One possibility is
that dark matter consists of weakly interacting massive particles (WIMPs), such as the
lightest stable particle in supersymmetry models.
Direct detection experiments look for nuclear recoils from WIMPs scattering in a
detector. The first generation of direct detection experiments were ultimately limited by
radioactive backgrounds. The Cryogenic Dark Matter Search (CDMS) is a direct detection
experiment based on novel particle detectors operated at millikelvin temperatures that
provide intrinsic background rejection. This capability, however, is not 100% effective.
Therefore a low background environment is essential to the experiment.
To create such an environment, all possible background sources have been extensively
studied both by measuring the background contribution from muons, photons and neutrons
and by performing detailed Monte Carlo simulations of the photon and neutron
backgrounds. The results of this investigation, as discussed in this thesis, have influenced
all aspects of the CDMS experiment.
The initial site for the CDMS experiment is the Stanford Underground Facility. The
relatively high muon flux at this site due to its shallow depth was balanced against the
convenience of a local site with the unlimited access necessary for operating a complicated
cryogenic system and developing new detector technology. The cryostat used to house the detectors was designed to accommodate the extensive shielding necessary to reduce
the ambient backgrounds to acceptable levels and to minimize the amount of radioactive
contamination near the detectors. Simulations and measurements of the local backgrounds
led to a layered shield design that consists primarily of plastic scintillators to veto muons,
lead and copper to attenuate photons and polyethylene to moderate neutrons.
With the background rejection capabilities of the cryogenic detectors and the low background
environment created in the Stanford Underground Facility, we expect to extend
the current limit on WIMP dark matter by more than an order of magnitude and begin
testing models for the lightest supersymmetric particle. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
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1544984 |
Negative regulators of hematopoiesis from normal and leukemic granulocytesAbdel-Kader, A. Karim 11 1900 (has links)
Hematopoiesis is controlled by a dynamic equilibrium between positive and negative
growth regulatory signals. Initially, much investigation focused on the positive regulatory
signals. The importance of the negative regulators in maintaining the tightly controlled limits on
cell numbers seen in vivo is now being appreciated. This thesis describes research into the role
of negative regulation in normal and leukemic hematopoiesis. The proteins believed to be
responsible for the inhibitory activity of two crude neutrophil preparations, one from patients
suffering from chronic myeloid leukemia (CML) and one from normal donors, have been
identified. Limited characterization of these activities on normal and leukemic hematopoiesis
has also been performed.
Previous work in our laboratory described an activity derived from immunoaffinity
enriched cell lysates of patients with chronic or acute myeloid leukemia (CML or AML). This
material demonstrated significant inhibition of growth of committed progenitor cells (especially
CFU-GM) from normal individuals (both human and murine) but did not inhibit equivalent
colonies from samples taken from patients with CML. Preliminary attempts to characterize this
material (referred to previously as CAMAL) isolated the active constituent to within a 30 to 35
kDa molecular size fraction.
Further purification of this activity was undertaken. Using reverse phase high pressure
liquid chromatography (rpHPLC) to fractionate the immunoaffinity enriched material, the
inhibitory activity was found to elute exclusively in a single rpHPLC fraction corresponding to
the leading portion of the peak corresponding to the 29 to 37 kDa serine protease homologue
azurocidin/CAP37. The main portion of the azurocidin peak was found to have no inhibitory
activity. Two-dimensional gel analysis of the active part of the peak and a reference of
azurocidin (isolated from normal azurophilic granules) showed no entity distinct from the
higher molecular weight glycoforms of azurocidin. As azurocidin is found within normal neutrophils, we purified this molecule from this
source. Only one of six azurocidin preparations from normal donors was found to contain
inhibitory activity on normal CFU-GM.
Recently, we have devoted our efforts to extend the identification and characterization
of a myelopoietic inhibitory activity originally described by Boyum and colleagues from normal
neutrophils (147). Using density gradient fractionation of neutrophil lysates, we localized the
activity to the cytosol and the specific granules fraction. Using sub-fractionation of
granulocytes, ammonium sulfate and heat precipitation coupled with size exclusion and anion
exchange chromatography, we have purified the molecule responsible for the inhibitory activity
on myeloid progenitors to a single, silver stained band of approximately 15 kDa. Identification
of this material as cytidine deaminase (CD) was established by Western blot analysis, the use
of recombinant cytidine deaminase and blockage of the inhibitory activity by the known
inhibitor of CD activity tetrahydrouridine (THU). Normal human, murine and CML
progenitors were equally susceptible to the inhibitory activity of this molecule. In addition the
proliferation and clonogenicity of various leukemic cell lines was also inhibited. Interestingly,
even at high concentrations (> 60 ng/ml) of pure recombinant CD, no more than a 70%
inhibition of myeloid colony formation was seen. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate
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1544985 |
Evaluation of anti-sperm monoclonal antibodies as biomarkers to assess bull sperm capacitation, acrosome reaction and fertility in vitroAmbrose, Divakar Justus 05 1900 (has links)
Anti-sperm monoclonal antibodies (mAbs) were evaluated as biomarkers to assess
capacitation, acrosome reaction, cryodamage and fertility of bull spermatozoa in vitro. Three
anti-human sperm mAbs crossreacting with bull sperm antigens were identified. They showed
time-dependent changes in binding to bull spermatozoa incubated under capacitation conditions
when assessed by indirect immunofluorescence, with maximum binding at 4 h. Bull and human
sperm antigens recognized by one mAb (HS-11) were isolated and their immunological
relatedness shown by ELISA. The possible relationship between fertility and the binding of HS-
11 to bull (n=8) spermatozoa was tested in a bovine in vitro fertilization system. In vitro
fertility based on cleavage of oocytes and mAb-binding to spermatozoa at 4 h incubation under
capacitation conditions were correlated (r=0.43; n=32; P<0.05), but in vivo fertility and
sperm-HS-11 binding were not correlated.
In the next set of experiments, 15 mAbs specific to bull sperm antigens were generated.
The mAbs were sperm-specific, but not species-specific. The mAbs identified five distinct
antigenic domains of bull spermatozoa. Seven of the 13 mAbs tested, recognized bull sperm
proteins of >200 kDa in western blots. Three detected more than one protein band (40-200
kDa), while three recognized none.
Thirteen of the 15 mAbs were tested for their influence on bovine sperm-zona
interactions in vitro. Sperm-zona binding was not affected by 12 mAbs. However, sperm-zona
binding in the presence of one surface-reacting mAb was higher than the control (23.6+5.6 vs
10.0+2.4 sperm/zona, mean+SE; P<0.001). Four mAbs specific to intra-acrosomal antigens
exhibited a time dependent increase (P<0.05) in binding to bull spermatozoa incubated under
capacitation conditions. In contrast, the binding of mAbs specific to surface antigens decreased (P < 0.05) after 4 h incubation in the presence of heparin. Following induced acrosome reaction,
a significant decrease (P<0.01) in the binding of acrosome-specific mAbs was observed. Four
selected mAbs were then evaluated as possible indicators of cryodamage in frozen-thawed bull
spermatozoa. Even though the mAbs showed higher binding to frozen-thawed spermatozoa,
there was no conclusive evidence to support the hypothesis that the mAbs will be useful to detect
live membrane-damaged spermatozoa. / Land and Food Systems, Faculty of / Graduate
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1544986 |
Surimi-based product development and viscous properties of surimi pasteBouraoui, Moez Mohamed 05 1900 (has links)
Raman spectroscopy was used to study the protein structure in raw and
salted surimi from Pacific whiting, and in gels formed by setting (32°C),
cooking (86°C) or setting followed by cooking. The intensity of the peaks
assigned to disulfide bond stretching vibrations increased considerably in the
cooked and set-cooked gels. A smaller increase was found in the gels that
were subject to setting alone. Secondary structure estimation based on the
amide I band indicated a change from predominantly a-helical structure in raw
surimi to similar proportions of a-helical and anti-parallel p-sheet after setting.
A further increase in anti-parallel p-sheet and decrease in a-helix content
occurred during the kamaboko stage. The intensity of C-H stretching
vibrations of the aliphatic residues decreased after salting, setting and
cooking. The set and cooked gel had a better gel strength and fold score
than the cooked gel which, in turn, had better properties than the set gel.
Response surface methodology was used to determine the optimal setting
and cooking time and temperature conditions resulting in a maximized gel
strength, fold score and color, (whiteness index), and a minimized gel
expressible liquid. Cooking temperature was the variable that had the
strongest influence on the gel quality characteristics. Level set programming, a global optimization method, gave essentially the same results as a gradient
based optimization method. The results obtained by these two methods were
better than those generated by the Simplex technique.
Using a formulation composed of pink salmon surimi, salt, whey protein
concentrate and wheat starch, an optimal final product, kamaboko sausage,
was developed. In addition, when this formulation was applied to herring
surimi, the kamaboko obtained had similar gel strength and elasticity as a
commercial surimi-based product. The effects of frozen storage conditions of
roe herring on its gel making ability (GMA) were investigated. Frozen storage
at around -45°C maintained the GMA for seventy days while storage at -83°C
further increased the GMA period.
The viscous properties of a salmon surimi paste were studied using a
rotational viscometer. The paste behaved as a shear thinning fluid with a
yield stress that increased with temperature up to 21 °C. Viscosity also
increased with temperature up to 21 °C, possibly because of protein-protein
interactions. The Theological data were reasonably well represented by a
simple model which takes into consideration the effects of both shear rate and
temperature. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate
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1544987 |
Relationships between cognitive and linguistic processes and second language production in French immersion programmesBournot-Trites, Monique 05 1900 (has links)
Some researchers believe that all French immersion students speak the same way and
that they make many transfer errors (borrowing English structures). Although these beliefs
are not founded on rigorous observations, current teaching strategies emphasize repeating
correct patterns rather than teaching according to student's individual differences.
My study posed two main questions. First, are there individual differences in the
quality of French spoken by French immersion students? Second, do individual differences
in cognitive and linguistic processes influence the type and frequency of errors observed in
French immersion students' language production?
To analyse individual differences in linguistic processes, I used variables from verbal
learning theory that measure Paradigmatic and Syntagmatic processes. I analysed
differences in cognitive processes with the PASS (Planning, Arousal/Attention,
Simultaneous and Successive processes) cognitive theory. PASS is operationalized in the
Cognitive Assessment System test (CAS). These theories generated a secondary purpose
for the study: to verify and explain the findings of Jarman's (1980) study concerning the
parallelism between Paradigmatic and Simultaneous processes, and between Syntagmatic
and Successive processes.
Data came from 89 girls and 63 boys from anglophone families in grade three French immersion schools in British Columbia. I analysed four areas of individual differences
(Paradigmatic and Syntagmatic processes; Simultaneous and Successive processes; Planning;
and Attention), and the relationship between these processes with Vocabulary, Grammar,
and Transfer Errors in oral and written French language production.
LISREL measurement models did not converge due to variables' low correlation.
Relationships between the variables were not found probably because of low reliabilities of
the CAS measures. A subsequent analysis used observed variables' models (multiple
regressions), rather than latent variables' models. The strongest relation was between
Planning and Attention, and Transfer Errors. Grammar Errors, rather than Transfer Errors
prevailed. Consequently, I suggested teaching methods reinforcing communicative sentence
structures.
As in Jarman (1980), cognitive and linguistic processes were not demonstrably
parallel. Contrary to what verbal learning researchers thought, various linguistic processes'
measures are not equivalent. Linguistic measures' constraint level as well as Planning level
affected my results. For further research, I proposed a model of linguistic tasks of various
constraint levels. / Education, Faculty of / Graduate
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1544988 |
Effects of cultural values and attribution of outcome feedback on reasoning in Canadian and Chinese college studentsYao, Min 05 1900 (has links)
The primary purpose of the present study was to investigate the joint effects of
culture and attribution of outcome feedback on reasoning performance. This study
attempted to address four major research questions: (a) Do Canadian and Chinese
students have different cultural values and causal attribution patterns? (b) Do pre-experimental
individual differences in causal attribution patterns lead to differences in
Canadian and Chinese students' inductive reasoning performance? (c) Does attribution
of outcome feedback affect Canadian and Chinese students' inductive reasoning
performance? (d) Do Canadian and Chinese students conduct deductive reasoning
differently as a function of outcome feedback and reasoning task contents?
A total of 120 college students (60 Canadian and 60 Chinese) performed three
phases of computerized experimental tasks. The research design involved 2 types of
culture groups (Canadian and Chinese) under 3 conditions of outcome feedback (success,
failure, and control) as two independent variables. The dependent variables observed
were the number of instances used or correct responses made and response time, when
possible.
In terms of culture differences, Canadian students appear to be distinct and
articulate about the matters of socio-cultural values, while Chinese students are relatively
less distinct and articulate. When making attribution for other people's success, both
Canadian and Chinese students held internal factors (i. e., good effort and high ability) as
responsible. When accounting for other people's failure, Canadian students picked
controllable factors (i.e., lack of effort), while Chinese students picked both controllable
and uncontrollable factors (i.e., largely lack of effort and occasionally difficult task) as
the reasons. However, following the success outcome feedback about their own
reasoning performance, Canadian students emphasized mostly high ability and,
occasionally, effort as the reasons, while Chinese students picked mostly good luck and,
occasionally, high ability. Given the failure outcome feedback about their own task
performance, Canadian students attributed to lack of effort and bad luck as causes, while
Chinese students exclusively picked lack of effort as the explanation.
Chinese subjects' inductive and deductive reasoning performances remained
relatively unswayed by success or failure outcome feedback, whereas Canadian subjects'
reasoning performance remained good only when success feedback was received. When
failure feedback was provided, Canadian subjects' reasoning performances deteriorated
and remained poor throughout the experiment.
While Chinese students' reasoning performance is not predictable from their low-ability
attribution of other people's failure outcome, Canadian students' reasoning
performance is highly predictable; that is, the more they attributed others' failure to low
ability, the faster they completed the culture-fair inductive reasoning task. On the other
hand, when making attribution based on their own experience, given success feedback,
Canadian students attributed their performance to their high ability. Given failure
feedback, Canadian students attributed their performance to their lack of effort, with
improved performance commensurable to their verbal causal attribution.
The present findings indicate that Canadian and Chinese college students showed
differences in causal attribution patterns, depending on when they explain others'
success/failure experiences or their own, and further that upon receipt of failure outcome
feedback, Canadian students' reasoning performance deteriorated, while Chinese
students' performance remained insensitive to success or failure outcome feedback.
Further fine-grained analyses of such causal attribution patterns interacting with outcome
feedbacks and cognitive performance needs some more careful studies. / Education, Faculty of / Educational and Counselling Psychology, and Special Education (ECPS), Department of / Graduate
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1544989 |
Moral perception in the nondual key : towards an ethic of moral proprioceptionBai, Hee-Soon 11 1900 (has links)
Moral actions characteristically emanate from moral perception; therefore, if
we are to improve moral action, we should see to improving moral
perception. Accordingly, this thesis prioritizes the importance of moral
perception in moral performance. Yet, perception is usually interpreted as
reception and, hence, lying outside one's direct control, in which case the
notion of improving moral perception would be limited. However, many
contemporary moral theorists who profess the primacy of moral perception
are rather strongly committed to such a notion as evidenced in their pursuit
of the possibility of open moral perception which is not rigidly prescribed by
prior doxastic and dispositional conditions. I problematize this situation by
arguing that in the way perception ordinarily operates, which is
superimposition of the subject's beliefs and dispositions on what is perceived,
moral perception as open perception is not possible in any serious sense.
Unless this superimposition is first of all recognized—a difficult task, given
our tendency to objectify what is perceived—and, secondly, given to
deconstruction in both theory and experience, the proposal for open
perception would not yield far-reaching results. I examine this tendency to
objectification and attempt to repudiate our foundational subject-object
dualistic epistemology and ontology that lie behind this tendency. Then I
consider how the resulting thesis of nonduality can be experientially
established. For this step, I explore the resources available in the Buddhist
tradition of vipassana theory and practice which proposes laying bare the
process of superimposition, and furthermore, deconstructing it experientially,
thereby availing to us the possibility of nondual moral perception—that is,
perception freed from the enthrallment of superimposition. I also explore
the epistemology and phenomenology behind vipassana, and I attempt to
picture human intentionality in the mode of nonduality. Furthermore, I
attempt to construct a general ethical theory, which I term "nondual ethic,"
that centralizes empathic, compassionate, and harmony-making perception.
Finally, I consider the kinds of educative practices that foster nondual ways of
experience, and hence nondual moral perception. With this thesis, I lay the
preliminary groundwork for further investigation. / Education, Faculty of / Graduate
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1544990 |
Patients’ and families’ perceptions of factors that affect recovery from cadiac disease : a rural community perspectiveWichmann, Laurel Lynne 05 1900 (has links)
This study used focus groups as a research method to elicit cardiac patients' and
families' perspectives of the factors that affect recovery from cardiac disease in a rural
community. The purpose of studying these perceptions was to gain an understanding of the
behavioral characteristics, environmental indicators and educational factors that affect their
recovery from heart disease. It was proposed that the behavioral and environmental forces
and educational factors impacting on the cardiac patients' health and recovery needed to be
understood before patients could be encouraged to participate actively in decision making
that affects their health. A health promotion model was used as a conceptual framework.
Eight males and three females participated in one of two focus groups and three males
and one female were interviewed individually as key informants. The ages of the participants
ranged from 45 to 79 years. From analysis of the data, themes were identified and significant
statements were used to describe the phenomenon under study.
The findings of this study suggest that although in-hospital cardiac education
programs can provide general information to patients and families, there is a need to give
specific information regarding the first few weeks at home and to provide early home support
by health care professionals to reinforce this information and to provide emotional support.
Knowledge of the available resources in the rural community is essential. A group setting for educational, psychosocial and physical exercise is beneficial.
However, families and physicians need to be educated to the benefits of these programs.
Alternative resources may be required for people who cannot or will not attend these groups. / Applied Science, Faculty of / Nursing, School of / Graduate
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