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Ultrasonic imaging and cortical thickness determination of long bonesZheng, Rui Unknown Date
No description available.
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An experimental and numerical study on the effect of some properties of non-metallic materials on the ice adhesion levelPiles Moncholi, Eduardo January 2013 (has links)
The rise of the Environmentalism in every sector of the Industry has lead the aircraft
and engine manufacturing companies to develop new generations of more
environmentally friendly engines. The companies, encouraged to this purpose, are in a
constant research for new manufacturing and production techniques, in order to improve
their products, from the environmental point of view, by gaining efficiency in the
manufacturing techniques and reduce the fuel consumption and emissions in-flight.
Having in mind this scenario, the sponsor of this Project is interested in understanding
how changing the materials of the blades, titanium alloys currently, for other lighter
materials, such as composites, is going to have an effect in the overall gas turbine
efficiency.
In the particular case of this Project, it will be studied the influence of the Stiffness and
coating Thickness of those non-metallic materials suitable to be employed as coatings
on gas turbine fan blades, from the icing point of view. The work procedure will be
based on a study of Linear Elastic Fracture Mechanics of bi-material junctions and will
extrapolate the general problem to the ice-coatings case, by getting experimental data
from tests carried out in an Icing Tunnel.
It will be observed that the coating Stiffness has an influence on the Adhesion Level of
ice to less stiff materials, if compared with the Adhesion Level of ice to metals. Besides,
it will be described how a 0.5 millimetres thin polymeric coating placed over a metallic
substrate is enough to reduce the Adhesion Level of ice, hiding any effect that the
underneath materials might have on the Adhesion Level.
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Synthesis and electrochemical modulation of the actuator properties of poly(phenazine-2,3-diimino (pyrrol-2-yl)).Botha, Shanielle Veronique. January 2008 (has links)
<p>The focus of this study is to synthesize a novel hinged polymer actuator. The linking molecule (hinge) is phenazine with interconnected dipyrrole units.</p>
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Persistence of Laminar Flamelet Structure Under Highly Turbulent CombustionYAMAMOTO, Kazuhiro, NISHIZAWA, Yasuki, ONUMA, Yoshiaki 08 1900 (has links)
No description available.
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乱流予混合火炎の燃焼診断に対するアセトン-OH同時PLIF計測手法の有効性の検討馬目, 聡, MANOME, Satoshi, 中村, 祐二, NAKAMURA, Yuji, 林, 直樹, HAYASHI, Naoki, 山本, 和弘, YAMAMOTO, Kazuhiro, 山下, 博史, YAMASHITA, Hiroshi 25 January 2007 (has links)
No description available.
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An experimental and numerical study on the effect of some properties of non-metallic materials on the ice adhesion levelPiles Moncholi, Eduardo January 2013 (has links)
The rise of the Environmentalism in every sector of the Industry has lead the aircraft and engine manufacturing companies to develop new generations of more environmentally friendly engines. The companies, encouraged to this purpose, are in a constant research for new manufacturing and production techniques, in order to improve their products, from the environmental point of view, by gaining efficiency in the manufacturing techniques and reduce the fuel consumption and emissions in-flight. Having in mind this scenario, the sponsor of this Project is interested in understanding how changing the materials of the blades, titanium alloys currently, for other lighter materials, such as composites, is going to have an effect in the overall gas turbine efficiency. In the particular case of this Project, it will be studied the influence of the Stiffness and coating Thickness of those non-metallic materials suitable to be employed as coatings on gas turbine fan blades, from the icing point of view. The work procedure will be based on a study of Linear Elastic Fracture Mechanics of bi-material junctions and will extrapolate the general problem to the ice-coatings case, by getting experimental data from tests carried out in an Icing Tunnel. It will be observed that the coating Stiffness has an influence on the Adhesion Level of ice to less stiff materials, if compared with the Adhesion Level of ice to metals. Besides, it will be described how a 0.5 millimetres thin polymeric coating placed over a metallic substrate is enough to reduce the Adhesion Level of ice, hiding any effect that the underneath materials might have on the Adhesion Level.
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Ice dynamics and mass balance in the grounding zone of outlet glaciers in the Transantarctic MountainsMarsh, Oliver John January 2013 (has links)
The Antarctic grounding zone has a disproportionately large effect on glacier dynamics and ice sheet stability relative to its size but remains poorly characterised across much of the continent. Accurate ice velocity and thickness information is needed in the grounding zone to determine glacier outflow and establish to what extent changing ocean and atmospheric conditions are affecting the mass balance of individual glacier catchments.
This thesis describes new satellite remote sensing techniques for measuring ice velocity and ice thickness, validated using ground measurements collected on the Beardmore, Skelton and Darwin Glaciers and applied to other Transantarctic Mountain
outlet glaciers to determine ice discharge. Outlet glaciers in the Transantarctic Mountains provide an important link between the East and West Antarctic Ice Sheets but remain inadequately studied. While long-term velocities in this region
are shown here to be stable, instantaneous velocities are sensitive to stresses induced by ocean tides, with fluctuations of up to 50% of the mean observed in GPS measurements. The potential error induced in averaged satellite velocity measurements due to these effects is shown to be resolvable above background noise in the grounding zone but to decrease rapidly upstream. Using a new inverse finite-element modelling
approach based on regularization of the elastic-plate bending equations, tidal flexure information from differential InSAR is used to calculate ice stiffness and infer thickness in the grounding zone. This technique is shown to be successful at reproducing the thickness distribution for the Beardmore Glacier, eliminating current issues in the calculation of thickness from freeboard close to the grounding line where ice is not in hydrostatic equilibrium. Modelled thickness agrees to within 10% of ground penetrating radar measurements. Calibrated freeboard measurements and tide-free velocities in the grounding zones of glaciers in the western Ross Sea are used to calculate grounding zone basal melt rates, with values between 1.4 and 11.8 m/a⁻¹ in this region. While strongly dependent on grounding line ice thickness and velocity, melt rates show no latitudinal trend between glaciers, although detailed error analysis highlights the need for much improved estimates of firn density distribution in regions of variable accumulation such as the Transantarctic Mountains.
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Paraoxonase 1 and the risk for cardiovascular disease in a mixed ancestry population of South AfricaMacharia, Muiruri 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Paraoxonase (PON) 1 is a high density lipoprotein (HDL) - bound antioxidant enzyme that
was originally discovered and better known for its role in protecting against organophosphate
(OP) - induced neurotoxicity. In the past two decades, the enzyme has gained prominence
as a protective agent against atherosclerosis on account of increasing evidence that it
accounts for many of the anti-atherogenic roles attributed to HDL. PON1 is a polymorphic
enzyme displaying a high variability in human populations which is associated with a
considerable degree of inter-individual differences in enzyme phenotype that translates to
differential risk for OP toxicity and cardiovascular disease (CVD). In a series of studies and
analyses, this thesis describes investigations regarding the possible involvement of PON 1 in
the risk for CVD in a mixed ancestry population from Bellville, Western Cape, South Africa.
This was done by evaluating the distribution of PON1 coding region polymorphisms (Q192R
and L55M) and their influence on PON1 phenotype as well as the latter‟s relation to CVD risk
factors (oxidative stress, inflammation and atherogenic dyslipidemia) and possible
involvement in early CVD assessed by measuring intima media thickness of the carotid
artery (CIMT).
Since PON1 is increasingly measured in samples that have been stored for varied periods of
time, the main study was preceded by a pilot study evaluating the influence of baseline
conditions on the stability of PON 1 activity and antioxidant status in human sera stored for
up to 12 months. It was shown that baseline glycemic status enhances the degradation of
antioxidants in stored samples with indications of also accelerating the decline of PON1
levels and activity. Thus baseline glycemic status should be a factor to be considered in
analyses involving stored samples.
The Q192R polymorphism was found to be the functional variant influencing both
concentration and activity of plasma PON1. Contrary to expectation, the L55M was nonfunctional,
possibly due to its unusual distribution in this population where the 55M (83%)
allele overwhelmingly predominated over the L55 allele. The R allele was the more frequent
(60.4%) of the 192 polymorphism. The R allele has previously been associated with less
efficient breakdown of lipid peroxides and a subsequent higher risk for atherosclerotic heart
disease while the 55M is recognized as a “low concentration/activity” variant. Thus the
predominant PON1 genotype distribution in this population constitutes a risk profile that may
relate to increased risk for CVD. The risk for CVD was confirmed to be very high in this population indicated by high
prevalence of the metabolic syndrome (48%) and its key components (and CVD risk factors)
diabetes (28%), obesity (53%) and high blood pressure (57%). Paraoxonase activity
associated inversely with indices of inflammation (high sensitive C- reactive protein [hs-CRP]
and leptin) and oxidative stress (oxidized low density lipoprotein [LDL]) and directly with
adiponectin and markers of systemic antioxidant status. These findings suggest that low
paraoxonase-I activity contributes to increased cardiovascular risk possibly via involvement
in early atherogenesis. However, only a modest inverse relation was observed between
PON1 phenotype and CIMT thus suggesting that PON1 may not play a major role in early
atherosclerosis.
Taken together, the findings presented in this thesis demonstrate the presence of a risk
PON1 genotypic profile and indication that the enzyme may play a role in the enhanced CVD
risk in this population possibly via interactions with inflammation and oxidative stress.
However, conclusive evidence for the involvement of PON1 in early CVD was not
demonstrated indicating a need to explore the participation of PON1 in later stages of CVD. / AFRIKAANSE OPSOMMING: Paraoksonase (PON) 1 is 'n antioksidant ensiem wat aan HDL gebind is. Oorspronklik is dit
ontdek en het bekend geword as 'n beskermer teen organofosfaat (OF)-gedrewe
neurotoksisiteit. In die afgelope twee dekades het die ensiem belangrik geraak as 'n
beskermer teen arterosklerose as gevolg van toenemende bewyse dat dit 'n belangrike rol
speel in die beskermende effekte van HDL teen arterosklerose. PON1 is 'n polimorfiese
ensiem wat groot variasie toon in verskillende populasies. Daar is ook inter-individuele
verskille in ensiem fenotipe wat uitloop op 'n differensiele risiko vir OF toksisiteit en
kardiovaskulêre hartsiekte (KVH). Hierdie tesis beskryf 'n reeks analises en ondersoeke
betreffende die moontlike betrokkenheid van PON1 in die risiko vir KVH in 'n gemengdeafkoms
populasie van Bellville, Wes-Kaap, Suid Afrika. Dit was gedoen deur die evaluering
van die verspreiding van die PON-1 koderende omgewing polimorfismes (Q192R en L55M),
hulle invloed op PON1 fenotipe en laasgenoemde se verhouding tot KVH risikofaktore
(oksidatiewe stress, inflammasie en arterogeniese dislipedimie) en moontlike voorkoms in
vroeë kardiovaskulêre siekte bepaal deur die meting van die intima media dikte van die
karotied slagaar.
Aangesien PON1 al hoe meer gemeet word in monsters wat vir verskeie tydperke gestoor
word, was die hoofstudie voorafgegaan deur 'n loodsstudie wat die invloed van basislyn
kondisies op die stabiliteit van PON1 aktiwiteit en antioksidant status in menslike sera wat vir
tot 12 maande gestoor was, bepaal het. Dis is duidelik aangetoon dat basislyn glisemiese
status die afbraak van antioksidante in gestoorde monsters verhoog het, asook aanduidings
van die afname van PON1 vlakke en aktiwitetit. Basislyn glisemiese status behoort dus ook
as 'n faktor ingereken te word in analises van gestoorde monsters.
Die Q192R polimorfisme is aangetoon om 'n funksionele variant te wees wat beide die
konsentrasie asook die aktiwiteit van PON1 beïnvloed het. Anders as wat verwag is, was die
L55M polimorfisme nie-funksioneel, moontlik as gevolg van sy ongewone distribusie in
hiedie populasie waar die voorkoms van die 55M (83%) alleel die L55 alleel oorheers het.
Die R alleel was die mees algemene (60.4%) van die 192 polimorfisme. Die R alleel is
voorheen reeds geassosieer met minder effektiewe afbraak van lipied peroksides en
gevolglike hoër voorkoms van arteriosklerotiese hartsiekte, terwyl die 55M erken word as 'n
“lae konsentrasie/aktiwiteit” variant. Die oorheersende PON1 genotipe distribusie in hierdie
populasie behels dus 'n risikoprofiel wat betrekkking mag hê op verhoogde KVH. Die risiko vir KVH was bevestig om baie hoog te wees in hierdie populasie, soos aangedui
deur 'n hoë voorkoms van die metaboliese sindroom (48%) en die sleutelkomponente
daarvan (insluitend KVH risikofaktore), diabetes (28%), obesiteit (53%) en hipertensie
(57%). Paraoksinase aktiwiteit was omgekeerd geassosieer met indekse van inflammasie
(hoë C-reaktiewe proteïen [hs-CRP] en leptien) en oksidatiewe stres (geoksideerde lae
digtheid lipoproteïen [LDL], en direk geassosieer met adiponektien en merkers van
sistemiese antioksidantstatus. Hierdie bevindings mag aandui dat lae paraoksonase-1
aktiwiteit bydra tot verhoogde kardiovaskulêre risiko, moontlik via betrokkenheid in vroeë
arterogenese. Slegs 'n klein omgekeerde verhouding is egter waargeneem tussen die PON1
fenotipe en karotied intima media dikte, wat mag aandui dat PON1 nie 'n beduidende rol
speel in vroeë arterosklerose nie.
In geheel, die bevindinge voorgedra in hierdie tesis demonstreer die voorkoms van 'n risiko
PON1 genotipiese profiel wat 'n aanduiding mag wees dat die ensiem 'n rol mag speel in die
verhoogde KVH risiko in hierdie populasie, moontlik deur interaksies met inflammasie en
oksidatiewe stress. Afdoende bewys van die betrokkenheid van PON1 in vroeë KVH was
egter nie gedemonstreer nie, wat die nodigheid aandui om die deelname van PON1 in latere
stadiums van KVH te ondersoek.
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EVALUATION OF MECHANICAL PROERTIES AND EFFECTIVE THICKNESS OF THE INTERFACES BY FINITE ELEMENT ANALYSISPulla, Sesha Spandana 01 January 2011 (has links)
The nanoindentation technique has been used to identify the interfaces between dissimilar materials and subsequently to evaluate the physical and mechanical properties across the interfaces. The interfaces could represent the interface (transition face) between oxidized and unoxidized polymers, the interface between rigid fiber and polymer matrix, or other similar situations. It is proposed to use a nanoindenter equipped with small spherical tip to indent across the interfaces of dissimilar materials. The proposed method has been validated by conducting a large number of virtual experiments through 3-dimensional finite element simulations, by varying the properties of the two dissimilar materials, including various combinations of modulus (E1/E2), yield strength (σy1/σy2), hardening index (n1/n2), interface sizes (R/T), Poisson’s ratio (ν), etc. The mechanical properties across the interfaces have been obtained, and a quantitative model for predicting the interface sizes has been established.
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Study of DXA-derived cortical bone thickness in assessing hip fracture riskLong, Yujia 14 August 2014 (has links)
Hip fracture has been identified as one of the main health problems in the elderly. To improve the accuracy in assessing subject-specific hip fracture risk, this study proposed normalized cortical bone thickness (NCBT) estimated from patient’s hip DXA as an alternative predictor of hip fracture risk. Hip fracture risk index (HFRI) derived from DXA-based finite element model was utilized as a baseline for evaluating the effectiveness of NCBT in predicting hip fracture risk. It was found that NCBT at the lateral side of the narrowest femoral neck had the strongest correlation with femoral neck HFRI among the six locations of the proximal femur. This study suggests that it is possible to use NCBT as a surrogate for a quick evaluation of hip fracture risk. Yet its clinical performances such as sensitivity to therapy effectiveness and the ability to discriminate clinical fracture cases will be investigated in a future study.
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