Large quantities of data have described left ventricular adaptation to endurance training, but basic concepts on left ventricular performance during exercise remain controversial. In this thesis, we present the results of studies of left ventricular dynamics during exercise in 89 endurance-trained athletes. Using radionuclide ventriculography, 35 female and 30 male endurance athletes were studied in supine position. During supine exercise at 70% of the age-expected maximal heart rate, the adjustments in left ventricular volumes were small, suggesting a high preload before exercise. Stroke volume increased by changes in the left ventricular end-diastolic volumes but no changes were observed in the end-systolic volumes. Moreover, no significant differences were noted between male and female athletes. Contrast echocardiography was utilized when 24 male endurance athletes were studied during upright exercise. An almost linear increase in stroke volume was seen from upright rest to upright exercise at a heart rate of 160 beats per minute. Stroke volume increased by an almost linear increase in end-diastolic volume and showed an initial small decrease in end-systolic volume. The left ventricular cavity became geometrically more spherical with the largest increase in the left ventricular end-diastolic short-axis cavity diameters in the mid and apical part of the left ventricle. Left ventricular long-axis length obtained from the epicardial apex to the middle of the mitral annulus at end-diastole showed no significant change from rest to exercise. The mitral annulus motion contributed to more than 50% of the stroke volume during exercise with no significant difference between septal and lateral annular motion at peak exercise. Major changes were observed in left ventricular filling indices during upright exercise. The mean transmitral pressure gradient showed a linear increase and increased several times as the mean diastolic time decreased, with large reductions in mean left ventricular filling time. Despite the shortened filling time, the heart was able to increase the filling rate (measured as volume per time) five times. This observation verifies that the heart has large reserves at rest and reveals the increase in capacity during exercise.

<p>The main purpose of this research is to investigate liquid entrainment mechanisms of annular flow by computational fluid dynamics (CFD) techniques. A numerical model is developed. The model is based on the physics of an upward annular flow. In the modeling, a transient renormalization group (RNG) k-å model in conjunction with enhanced wall treatment method was employed. In order to reconstruct the two-phase interface, the geometric reconstruction scheme of volume of fluid (VOF) model was adopted. Fluent® 6.18 was used as the solution tool. Simulation results indicated that disturbance waves were generated first on the two-phase interface and their evolution eventually resulted in the liquid entrainment phenomena. The most significant accomplishment of this work is that details of the entrainment mechanisms are well described by the numerical simulation work. In addition, two new entrainment mechanisms are presented. One entrainment mechanism demonstrates that the evolution of individual waves causes the onset of liquid entrainment; the other mechanism shows that the coalescence of two adjacent waves (during the course of their evolution) plays an important role in the progression of liquid entrainment. The newly developed entrainment mechanisms are based on conservation laws. In order to explore the flow physics of the targeted annular flow, the law of the wall, in conjunction with an analytical model based on a force balance, was applied to previously collected experimental data. Results indicated that the film flow had strong features of near-wall flow. In addition, based on prior experimental work and a newly developed physical wave model by researchers in the Microgravity Research Group, University of Saskatchewan, a steady RNG k-å model, in conjunction with the enhanced wall treatment method, was applied to the gas core. The simulation results showed turbulent flow features in the gas core and strong effects of the interfacial waves on the simulation results. The above information forms the physical foundation for the simulation work on the entrainment mechanism.</p><p>One significant contribution to the authors research group is the liquid entrainment fraction data. A new method was introduced to make the measurements. The method combined a chemically-based titration method with a newly-designed instrument, a separator, to effectively measure the entrainment fraction. Experiments were conducted at low system pressure (~ 1 atm) and relatively low gas and liquid superficial velocities (Vsg = 25.8 m/s to 45.5 m/s, and Vsl = 0.15 m/s to 0.30 m/s, respectively). The entrainment fraction was found to be under 7 %, with a maximum uncertainty of 0.26 % for all the experimental set points. Repeatability test results and comparisons with previous entrainment data indicated that the new technique can perform as well as other measurement techniques.</p>

The classical problem of predicting the atmospheric circulation response to extratropical surface forcing is revisited in the context of the observed connection between autumn snow cover anomalies over Eurasia and the wintertime Northern Annular Mode (NAM). In general circulation model (GCM) simulations with prescribed autumn Siberian snow forcing, a vertically propagating Rossby wave train is generated, driving dynamical stratospheric warming and a negative NAM response that couples to the troposphere. It is shown that unexplained aspects of the evolution of this response can be clarified by examining the time evolution of the phasing, and hence the linear interference, between the wave response and the background climatological wave. When the wave response and background wave are in phase (out of phase), wave activity into the stratosphere is amplified (attenuated) and the zonal mean stratosphere-troposphere NAM response displays a negative (positive) tendency. This effect is probed further in a simplified GCM with imposed lower tropospheric cooling. As in the comprehensive GCM, linear interference strongly influences the NAM response. The transition from linear to nonlinear behaviour is shown to depend on forcing strength. Linear interference also plays a key role in the observed October Eurasian snow cover-NAM connection. It is shown that the time lag between October Eurasian snow anomalies and the peak wave activity flux arises because the Rossby wave train associated with the snow is out of phase with the climatological stationary wave from October to mid-November. Beginning in mid-November, the associated wave anomaly migrates into phase with the climatological wave, leading to constructive interference and anomalously positive upward wave activity fluxes. Current generation climate models do not capture this behaviour. Linear interference is not only associated with stratospheric warming due to Eurasian snow cover anomalies but is a general feature of both Northern and Southern Hemisphere stratosphere-troposphere interactions, and in particular dominated the negative NAM events of the fall-winter of 2009-2010. The interannual variability in upward wave activity flux during the season of strongest stratosphere-troposphere interactions is primarily determined by linear interference of quasi-stationary waves. The persistence of the linear interference component of this flux may help improve wintertime extratropical predictability.

The classical problem of predicting the atmospheric circulation response to extratropical surface forcing is revisited in the context of the observed connection between autumn snow cover anomalies over Eurasia and the wintertime Northern Annular Mode (NAM). In general circulation model (GCM) simulations with prescribed autumn Siberian snow forcing, a vertically propagating Rossby wave train is generated, driving dynamical stratospheric warming and a negative NAM response that couples to the troposphere. It is shown that unexplained aspects of the evolution of this response can be clarified by examining the time evolution of the phasing, and hence the linear interference, between the wave response and the background climatological wave. When the wave response and background wave are in phase (out of phase), wave activity into the stratosphere is amplified (attenuated) and the zonal mean stratosphere-troposphere NAM response displays a negative (positive) tendency. This effect is probed further in a simplified GCM with imposed lower tropospheric cooling. As in the comprehensive GCM, linear interference strongly influences the NAM response. The transition from linear to nonlinear behaviour is shown to depend on forcing strength. Linear interference also plays a key role in the observed October Eurasian snow cover-NAM connection. It is shown that the time lag between October Eurasian snow anomalies and the peak wave activity flux arises because the Rossby wave train associated with the snow is out of phase with the climatological stationary wave from October to mid-November. Beginning in mid-November, the associated wave anomaly migrates into phase with the climatological wave, leading to constructive interference and anomalously positive upward wave activity fluxes. Current generation climate models do not capture this behaviour. Linear interference is not only associated with stratospheric warming due to Eurasian snow cover anomalies but is a general feature of both Northern and Southern Hemisphere stratosphere-troposphere interactions, and in particular dominated the negative NAM events of the fall-winter of 2009-2010. The interannual variability in upward wave activity flux during the season of strongest stratosphere-troposphere interactions is primarily determined by linear interference of quasi-stationary waves. The persistence of the linear interference component of this flux may help improve wintertime extratropical predictability.

Published scientific work indicates that residential large diameter drinking water wells are at a higher risk of contamination from surface water impacts than drilled wells. The possibility of a higher incidence of contamination of large diameter wells is attributed to site selection and construction problems such as leaking joints in the well casing, ineffective annular sealant placed between the well casing and the formation, a poorly fitted cover with an access lid that promotes contaminant entry and air entry without adequate air filtration, well location down gradient of septic effluent sources, and depth limitations due to improper equipment used to advance the well which results in shallow wells often situated in topographical lows. In some situations, flaws in the well design were actually deliberate measures intended to capture surface water at sites with low groundwater yield. Historically, residential drinking water well performance studies have focussed on existing wells; however, uncertainty in the actual well construction methods and materials, well age and maintenance efforts have been problematic. A field and laboratory study was completed to assess the performance of several design changes that were thought to improve the integrity of large diameter drinking water wells, and to determine whether one design is more prone to atmospheric and/or surface water contamination than the other. Four large diameter residential wells were installed at a study site in Lindsay, Ontario. Three of these wells are constructed with enhanced construction methods (two using a cement tile casing and one using a galvanized steel casing) and annular sealants, while the fourth was constructed using conventional methods for cement cased wells. The enhanced test wells utilized a sealant between the casing sections, various annular sealants between the formation and the well casing, sanitary waterline connections, and ventilation with air filtration. The well constructed using outdated methods did not have any of these advanced features. An automated water extraction system removed about 875 L/day from each well to mimic residential usage. Routine monitoring, and laboratory and field testing were used to collect pertinent data required for this performance assessment. Routine monitoring involved the visual inspection of the wells, collection of well water elevation, collection of soil temperature profile data, collection and analysis of water samples, and collection of cumulative water volumes purged from the test wells. A biofilm cleaning study and analysis of cement-bentonite grout was conducted in the laboratory while smoke and aqueous tracer tests were conducted in the field. The biofilm cleaning study entailed growing a biofilm on different large diameter well casing materials and applying cleaning methods thought to be practical for cleaning the interior walls of large diameter wells. Different mixtures of cement-bentonite grout were subjected to volume measurements, vertical load bearing capacity analysis, and hydraulic conductivity analysis to determine their suitability as a potential annular sealant. The tracer tests were developed to determine whether pathways for either airborne contaminants or surface water to enter the test wells exist. The test wells were filled with smoke and monitored for potential atmospheric pathways. A tracer solution was infiltrated around the test wells and the interior of the tests wells were monitored for potential pathways for surface water to enter. Bacteriological indicators were detected in all test wells. The smoke tracer tests demonstrated that pathways for airborne contaminants to enter the test wells exist with more pathways observed in the winter than the summer. The aqueous tracer tests highlighted several areas where surface water could enter the test wells if ponding occurred around the well casing. As expected the enhanced test wells performed much better than the conventional test well for both of these tracer tests. The results of the biofilm cleaning study indicated that galvanized steel or fibreglass casing materials were the only materials able to be cleaned effectively. The best method in this study to remove biofilm from casing materials was pressure washing. The results from the cement-bentonite grout investigation indicated that cement-bentonite grout with 5% bentonite would make the most suitable annular sealant as its volume changed the least during curing, it was strong enough to support the load from maintenance efforts, and was the most impervious. The results of this study indicate that large diameter wells constructed with a proper annular sealant, sealant between casing sections and a sanitary waterline connection are less prone to contamination. Monitoring of the test wells should continue as they mature to determine whether this plays a significant role in their ability to prevent contamination of large diameter wells. Smoke tracer tests should be conducted again during the winter to determine if temperature was the cause of increased atmospheric pathways. A field-scale method to remove biofilm from the interior casing wall of large diameter wells should be developed and tested. A field-scale investigation of cement-bentonite grout for use as an annular sealant should be completed. Fibreglass casings can be fabricated as a continuous piece with no seams or joints and hence another well should be constructed and studied using corrugated fibreglass (NSF ANSI 61) casing.

Published scientific work indicates that residential large diameter drinking water wells are at a higher risk of contamination from surface water impacts than drilled wells. The possibility of a higher incidence of contamination of large diameter wells is attributed to site selection and construction problems such as leaking joints in the well casing, ineffective annular sealant placed between the well casing and the formation, a poorly fitted cover with an access lid that promotes contaminant entry and air entry without adequate air filtration, well location down gradient of septic effluent sources, and depth limitations due to improper equipment used to advance the well which results in shallow wells often situated in topographical lows. In some situations, flaws in the well design were actually deliberate measures intended to capture surface water at sites with low groundwater yield. Historically, residential drinking water well performance studies have focussed on existing wells; however, uncertainty in the actual well construction methods and materials, well age and maintenance efforts have been problematic. A field and laboratory study was completed to assess the performance of several design changes that were thought to improve the integrity of large diameter drinking water wells, and to determine whether one design is more prone to atmospheric and/or surface water contamination than the other. Four large diameter residential wells were installed at a study site in Lindsay, Ontario. Three of these wells are constructed with enhanced construction methods (two using a cement tile casing and one using a galvanized steel casing) and annular sealants, while the fourth was constructed using conventional methods for cement cased wells. The enhanced test wells utilized a sealant between the casing sections, various annular sealants between the formation and the well casing, sanitary waterline connections, and ventilation with air filtration. The well constructed using outdated methods did not have any of these advanced features. An automated water extraction system removed about 875 L/day from each well to mimic residential usage. Routine monitoring, and laboratory and field testing were used to collect pertinent data required for this performance assessment. Routine monitoring involved the visual inspection of the wells, collection of well water elevation, collection of soil temperature profile data, collection and analysis of water samples, and collection of cumulative water volumes purged from the test wells. A biofilm cleaning study and analysis of cement-bentonite grout was conducted in the laboratory while smoke and aqueous tracer tests were conducted in the field. The biofilm cleaning study entailed growing a biofilm on different large diameter well casing materials and applying cleaning methods thought to be practical for cleaning the interior walls of large diameter wells. Different mixtures of cement-bentonite grout were subjected to volume measurements, vertical load bearing capacity analysis, and hydraulic conductivity analysis to determine their suitability as a potential annular sealant. The tracer tests were developed to determine whether pathways for either airborne contaminants or surface water to enter the test wells exist. The test wells were filled with smoke and monitored for potential atmospheric pathways. A tracer solution was infiltrated around the test wells and the interior of the tests wells were monitored for potential pathways for surface water to enter. Bacteriological indicators were detected in all test wells. The smoke tracer tests demonstrated that pathways for airborne contaminants to enter the test wells exist with more pathways observed in the winter than the summer. The aqueous tracer tests highlighted several areas where surface water could enter the test wells if ponding occurred around the well casing. As expected the enhanced test wells performed much better than the conventional test well for both of these tracer tests. The results of the biofilm cleaning study indicated that galvanized steel or fibreglass casing materials were the only materials able to be cleaned effectively. The best method in this study to remove biofilm from casing materials was pressure washing. The results from the cement-bentonite grout investigation indicated that cement-bentonite grout with 5% bentonite would make the most suitable annular sealant as its volume changed the least during curing, it was strong enough to support the load from maintenance efforts, and was the most impervious. The results of this study indicate that large diameter wells constructed with a proper annular sealant, sealant between casing sections and a sanitary waterline connection are less prone to contamination. Monitoring of the test wells should continue as they mature to determine whether this plays a significant role in their ability to prevent contamination of large diameter wells. Smoke tracer tests should be conducted again during the winter to determine if temperature was the cause of increased atmospheric pathways. A field-scale method to remove biofilm from the interior casing wall of large diameter wells should be developed and tested. A field-scale investigation of cement-bentonite grout for use as an annular sealant should be completed. Fibreglass casings can be fabricated as a continuous piece with no seams or joints and hence another well should be constructed and studied using corrugated fibreglass (NSF ANSI 61) casing.

Dreissenid mussels alter particle transport dynamics in the near shore environment of the Great Lakes by intercepting, retaining and recycling suspended solids that might otherwise be exported to the offshore environment (Hecky et al., 2004). Particulate materials filtered from the water column by dreissenids are subsequently released as either feces or pseudofeces (Walz, 1978). This bio-transformation process alters the nature (grain size distribution, settling velocity and density) and transport properties (critical shear stress for erosion, erosion rates and bed stability) of particulate matter in surficial sediments. While knowledge of the transport characteristics of this material is required to refine particle transport dynamics and energy flow models in the Great Lakes, few studies have been specifically conducted to directly quantify these processes. An annular flume was used to determine the bed stability, rate of erosion and critical shear stress for erosion of dreissenid biodeposits. Materials studied in the flume consisted of 1) a combination of biodeposits and surface sediments collected from dreissenid beds and 2) biodeposits harvested in a weir box with dreissenids. The results show that erosion characteristics and sediment transport properties were strongly influenced by bed age; however particle sizes did not increase in the presence of mussels as originally speculated. Bed stability increased after 7 days, with a τcrit of 0.26 Pa compared to the 2 and 14 day consolidation periods (τcrit= 0.13 and 0.15 Pa respectively). In 2010, following a 2 day consolidation period, pure biodeposits harvested in the weir box had a critical shear stress for erosion of 0.052 Pa. The decrease in bed stability found in biodeposits from 2010 compared to the 2008 biodeposit mixture, may be a result of a more diffuse biofilm developing on the highly organic substrate. The mixture of biodeposits collected in 2008 were a combination organic and inorganic materials which may be creating a nutrient limited environment, where biofilm structure consists of more tightly organized biofilm cells and as a result enhance stability in the bed sediments. The decrease observed after 14 days is likely a result of the microbes depleting their resources and dying off. Due to the added roughness the mussels created in the flume, τcrit could not be measured and critical revolutions per minute (RPM) for erosion are reported for flume runs with mussels. During experiments conducted in 2009 with pure biodeposits and mussels the critical RPM was 5.83 while in 2010 in the presence of mussels a critical RPM was not observed. Settling experiments found biodeposits from both years (2008 and 2010) had decreased settling velocities when compared to different sediment types from lacustrine environments. I speculate that the added enrichment of the surficial sediments by mussel biodeposits is enhancing the process of biostabilization and increasing the bed stability and that the presence mussels themselves may additionally be enhancing bed stability by inhibiting flow from reaching the surface sediments/biodeposits.

<p>The main purpose of this research is to investigate liquid entrainment mechanisms of annular flow by computational fluid dynamics (CFD) techniques. A numerical model is developed. The model is based on the physics of an upward annular flow. In the modeling, a transient renormalization group (RNG) k-å model in conjunction with enhanced wall treatment method was employed. In order to reconstruct the two-phase interface, the geometric reconstruction scheme of volume of fluid (VOF) model was adopted. Fluent® 6.18 was used as the solution tool. Simulation results indicated that disturbance waves were generated first on the two-phase interface and their evolution eventually resulted in the liquid entrainment phenomena. The most significant accomplishment of this work is that details of the entrainment mechanisms are well described by the numerical simulation work. In addition, two new entrainment mechanisms are presented. One entrainment mechanism demonstrates that the evolution of individual waves causes the onset of liquid entrainment; the other mechanism shows that the coalescence of two adjacent waves (during the course of their evolution) plays an important role in the progression of liquid entrainment. The newly developed entrainment mechanisms are based on conservation laws. In order to explore the flow physics of the targeted annular flow, the law of the wall, in conjunction with an analytical model based on a force balance, was applied to previously collected experimental data. Results indicated that the film flow had strong features of near-wall flow. In addition, based on prior experimental work and a newly developed physical wave model by researchers in the Microgravity Research Group, University of Saskatchewan, a steady RNG k-å model, in conjunction with the enhanced wall treatment method, was applied to the gas core. The simulation results showed turbulent flow features in the gas core and strong effects of the interfacial waves on the simulation results. The above information forms the physical foundation for the simulation work on the entrainment mechanism.</p><p>One significant contribution to the authors research group is the liquid entrainment fraction data. A new method was introduced to make the measurements. The method combined a chemically-based titration method with a newly-designed instrument, a separator, to effectively measure the entrainment fraction. Experiments were conducted at low system pressure (~ 1 atm) and relatively low gas and liquid superficial velocities (Vsg = 25.8 m/s to 45.5 m/s, and Vsl = 0.15 m/s to 0.30 m/s, respectively). The entrainment fraction was found to be under 7 %, with a maximum uncertainty of 0.26 % for all the experimental set points. Repeatability test results and comparisons with previous entrainment data indicated that the new technique can perform as well as other measurement techniques.</p>

Most of reports deal with bounded simply-connected domains; only a few involve in exterior and annular problems (Chen et al. [3], Katsuroda[10] and Ushijima and Chibu [30]). For exterior problems of Laplace's equations, there exist two kinds of infinity conditions, (1) |u|≤C and (2) u=O( ln r), which must be complied with by the fundamental solutions chosen. For u=O(ln r), the traditional fundamental solutions can be used. However, for |u|≤C, new fundamental solutions are explored, with a brief error analysis. Numerical experiments are carried out to verify the theoretical analysis made. Numerical experiments are also provided for annular domains, to show that the method of fundamental solutions (MFS) is inferior to the method of particular solutions (MPS), in both accuracy and stability. MFS and MPS are classified into the Trefftz method (TM) using fundamental solutions (FS) and particular solutions (PS), respectively. The remarkable advantage of MFS over MPS is the uniform $ln|overline{PQ_i}|$, to lead to simple algorithms and programming, thus to save a great deal of human power. Hence, we may reach the engineering requirements by much less efforts and a little payment. Besides, the crack singularity in unbounded domain is also studied. A combination of both PS and FS is also employed, called combination of MFS. The numerical results of MPS and combination of MFS are coincident with each other. The study in this thesis may greatly extend the application of MFS from bounded simply-connected domains to other more complicated domains.

The annular-return flow and the utility of small-scale, combustion-based actuators for its control are investigated experimentally. The annular return flow is generated by an axial primary round jet, which impinges normally on a bounded end wall of a concentric tube, subsequently reverses direction, and exits the tube in a countercurrent flow to the primary jet. The combustion-based actuator generates a momentary (pulsed) jet that is produced by the ignition of a mixture of gaseous fuel and oxidizer in a small (cubic centimeter scale) combustion chamber. The operating frequency and the phase can be continuously varied by independently controlling the flow rate of the fuel/oxidizer and the ignition frequency. Two radially-opposing actuators are mounted on the wall of the annular return tube and are used to trigger flow transients that alter the global flow through strong feedback. The characteristics of the baseline flow and the effects of actuation are investigated using particle image velocimetry (PIV) as well as static and unsteady pressure measurements. The baseline flow is highly unstable, exhibiting very high rates of flow recirculation. The actuator jet acts as an azimuthal obstruction deflecting the primary jet and causing it to flow around the actuator jet. Furthermore, the interaction of the primary jet with the actuator jets generates large-scale circulation domains.