Groundwater flow in the capillary fringe is rarely measured during hydrogeological studies because of the difficulties associated with investigating this region. Previous research using a point velocity probe (PVP) to investigate groundwater velocity below the water table suggested that the PVP may also be capable of measuring groundwater velocity within the capillary fringe. The earlier PVP was redesigned for this study to allow for groundwater velocity data to be collected remotely. Using this system, groundwater velocity in the capillary fringe was investigated under field and laboratory conditions. Field experiments to investigate horizontal flow in the capillary fringe were conducted either by collecting vertical velocity profiles across the water table, or by holding the probe stationary and allowing seasonal recharge to move the capillary fringe and water table past the probe. Laboratory experiments were conducted in a controlled flow tank that simulated regions of an aquifer up to 85 cm above the water table. The redesigned PVP performed well as a remote system and provided velocity measurements up to 12 cm above the water table under field conditions. These values were consistent with those measured below the water table. In the laboratory, under conditions of drainage, groundwater velocity measurements in the capillary fringe consistent with values below the water table were measured up to 44 cm above the water table. The ability to measure horizontal flow of groundwater in the capillary fringe may open up new avenues for research in the study of contaminant transport in phreatic aquifers.

Cardiac resynchronization therapy (CRT) has recently emerged as an effective treatment option for heart failure patients with dyssynchrony. Patients have traditionally been chosen for CRT based on a prolonged QRS interval. However, this selection method is far from ideal, as approximately 30% of those receiving CRT do not show any clinical improvement. Tissue Doppler imaging (TDI) suggests that one of the best predictors of response to CRT is the underlying level of mechanical dyssynchrony in the myocardial wall prior to CRT. As a result, there has been growing interest in direct imaging of the myocardial wall. Because myocardial contraction is a complex, three-dimensional movement, providing an accurate picture of myocardial wall motion can be challenging. Echocardiography initially emerged as the modality of choice, but the long list of limitations (limited echocardiographic windows, one direction of motion, poor reproducibility) has fostered interest in exploring the use of MR for myocardial wall imaging. Although MR presents some unique drawbacks (expensive equipment, longer imaging times), it is able to overcome many of the limitations of TDI. In particular, Phase Velocity Mapping (MR PVM) can provide a complete, three-directional description of motion throughout the entire myocardial wall at high spatial and temporal resolution. The overall goal of this project was to develop a patient-selection method for CRT based on myocardial wall velocities acquired with MR PVM. First the image acquisition and post-processing protocols for MR PVM imaging of myocardial tissue were developed. A myocardial motion phantom was used to verify the accuracy of, and optimize the acquisition parameters for, the developed MR PVM sequence. Excellent correlation was demonstrated between longitudinal myocardial velocity curves acquired with the optimized MR PVM sequence and Tissue Doppler velocities. A database describing the normal myocardial contraction pattern was constructed. A small group of dyssynchrony patients was compared to the normal database, and several areas of delayed contraction were identified in the patients. Furthermore, significantly higher levels of dyssynchrony were detected in the patients than the normal volunteers. Finally, a method for computing transmural, endocardial, and epicardial, radial strains and strain rates from MR PVM velocity data was developed

The mechanical and transport properties of porous and cracked media, such as velocity and permeability, are sensitive to the effects of effective pressure, which itself is a function of the confining pressure and the pore-fluid pressure. The dependence of permeability and velocity on effective pressure has previously been modeled using the Bed-of-Nails asperity-deformation model. The main objective of this research was to explore the sensitivity of the Bed-of-Nails and effective-pressure models to random, Gaussian errors, by using an inverse approach. To achieve this, numerical modeling of pre-existing velocity and permeability experimental data sets was done. Extrapolation to 600 MPa was performed using an epidosite data set of compressional velocity as a function of confining pressure, only using measurements in the range 0-100 MPa. The results showed that, given sufficient data and considering random error only, extrapolation can be done with a level of error of less than 1.5%. Model error can also be significant in this type of exercise because it can give rise to systematic misfit, although in this case it was shown that the effects of model error were not considerable. Modeling the variation of compressional velocities as a function of confining and pore-fluid pressures in a deep-sea chalk showed that the best-fitting asperity-deformation model is sensitive to the effective-pressure model. Measurements of permeability in a Navajo-sandstone specimen as a function of confining pressure were numerically modeled, and the results showed that measurements made at low pressures, specifically near Pe = 0, are very important to constrain the model. The same result was found in the case of permeability as a function of confining and pore-fluid pressure in a Wilcox-shale where the lack of measurements near Pe = 0 caused the error in the model parameters to be overestimated. This occurs because the rate of change of permeability as a function of effective pressure is very high at low pressures. The lack of sufficient data near Pe = 0 overestimates the curvature matrix and, therefore, the errors in the model parameters.

The Tsallis entropy is applied to derive both 1-D and 2-D velocity distributions in an open channel cross section. These distributions contain a parameter m through which the Tsallis entropy becomes a generalization of the Shannon entropy. Different m parameter values are examined to determine the best value for describing the velocity distribution.Two Lagrangian parameters that are involved in the final form of 1-D velocity distribution equation are determined from observations of mean velocity and the maximum velocity at the water surface. For channels which are not wide and where the maximum velocity does not occur at the water surface, a 2-D velocity distribution is more appropriate. The Tsallis entropy is applied to derive 2-D velocity distributions. A new parameter M is introduced which represents the hydraulic characteristics of the channel. The derived velocity distributions are verified using both field data and experimental data. The advantages are found by comparing with Parandtl-von Karman, power law and Chiu’s velocity distributions.

Conventional ion imaging techniques utilized grid electrodes to extract and to accelerate ions toward the detector. The disadvantages of grid electrodes caused transmission reduction, severe image distortions and image blur due to the non-point source geometry. All these problems can be solved by the utilization of an open lens electrode assembly. In velocity mapping, the extracting electric field of an open electrostatic lens that projects the ion cloud onto the detector. The major advantage of the combination of ion lens optics and two-dimensional detection is that ions from different positions with the same initial velocity vector would be mapped onto the same position on the detector, which was named ¡§ velocity map imaging .¡¨ The kinetic energy resolutions achievable with this method are not generally considered as being competitive with the best photofragment translational spectroscopy technique. But Ashfold and co-workers have demonstrated that velocity imaging methods can provide dissociation energy with one wavenumber resolution, i.e., it compares favourably with all rival photofragment translational spectroscopy techniques. We construct an ion imaging apparatus and the pressure inside can be maintained at ~ 10-6 Torr with differential pumping when the pulsed nozzle is shut off. The pressure in the source chamber raises from 2.1¡Ñ10-6 to 1.0¡Ñ10-5 Torr and the pressure in the photolysis chamber raises from 2.4¡Ñ10-7 to 3.6¡Ñ10-7 Torr, when the pulsed nozzle is turned on with a stagnation pressure at 3 bar. Because reactive chemicals attack the piezo disk translator and ruin the Viton O-ring, a modified pulsed nozzle and Teflon O-ring are adopted to overcome these problems. This pulsed nozzle is mounted on a three-dimensional translational stage such that the nozzle can be aligned inside vacuum. The homogeneity of the accelerating electric field is crucial to the performance of the ion imaging apparatus. To meet this requirement, parallel electrodes of identical dimensions have been assured in the manufacture of the ion lens assembly.

Cyclone separators are widely used in agricultural processing industries as air pollution abatement devices. The performance of cyclones is a function of the geometry of the cyclone, operating parameters, and the particle size distribution (PSD) of the entrained aerosol. Multiple models have been proposed to predict the performance of cyclones given different geometric proportions, but many of these models do not quantify changes in performance with changes in inlet velocity or cyclone diameter given fixed geometric proportions. The Texas A&M Cyclone Design (TCD) method is a simple method for designing cyclones based on an inlet design velocity. The TCD method specifies “ideal” inlet velocities of 975 ± 120 m/min (3200 ± 400 fpm) and 914 ± 120 m/min (3000 ± 400 fpm) for 1D3D and 2D2D cyclones, respectively. However, there is evidence that higher dust collection efficiencies may be obtained from cyclones using different inlet velocities than those specified as the “ideal” velocity. Furthermore, the TCD method assumes that cyclone performance is independent of cyclone diameter. The present research demonstrates that, for large particles, the collection efficiency of 15.24 cm (six inch) diameter 1D3D and 2D2D cyclones is similar for inlet velocities from 10.16 standard m/s (2000 fpm) up to the design velocity, with significantly lower pressure drop at lower inlet velocities, resulting in lower energy requirements. However, the performance of cyclones is a function of cyclone diameter. Using similar operating parameters, the collection efficiency of a 60.96 cm (24 inch) diameter 1D3D cyclone was significantly lower (α = 0.05) than that of a 15.24 and a 30.48 cm (6 and 12 inch) diameter cyclone, and the collection efficiency of a 91.44 cm (36 inch) cyclone was significantly lower (α = 0.05) than that of a 60.96 cm (24 inch) diameter cyclone. The results of this research suggests the need for a new mathematical model to predict the performance of cyclones.

<p>The purpose of air distribution systems for HVAC is tocreate proper air quality and thermal conditions in an occupiedzone. In mixing type air distribution systems air is suppliedinto a room through various types of outlets and distributed byturbulent air jets. These air jets are the primary factorsaffecting room air motion. The ASHRAE handbook recognises fourmajor zones of maximum velocity decay along a jet.</p><p>Although numerous theoretical and experimental studies havebeen conducted to develop turbulent air jet theory from the1930's, air jet performance in the further field from theoutlet is still not well understood.</p><p>Many studies were therefore carried out, and the followingconclusions can be drawn from them:</p><p>    The end centerline velocities of zone 3 for both "free"jet and wall jet could strongly depend on the outletvelocities and room size.</p><p>    The<i>K</i>-value of wall jets could be a function of bothoutlet velocities and outlet size.</p><p>    It is very important to choose suitable sampling time toevaluate jet performance.</p><p>    CFD can not always be used to predict jet behaviour,especially for the jet with low outlet velocity and in thearea far away from the outlet. However, for a two-dimensionwall jet, CFD could be a powerful tool for designers.</p><p><b>KEYWORDS</b>: air jet, centerline velocity,<i>K</i>-velocity, air diffuser, ventilation, measurement,CFD</p>

The focus of this work is the experimental investigation of electron velocity distribution functions in the plasma of the Texas Helimak experiment. Texas Helimak has a cylindrical geometry and relatively moderate plasma parameter, which allow the use of a retarding field analyzer that is located approximately in the middle of the vacuum vessel. Electron velocity distribution functions were measured for a variety of different operating conditions and for two gas species, namely argon and helium. Parameter scans, whereby all parameter except the scan parameter were kept constant, were done in order to investigate the influence of the scan parameter on the velocity distribution. It was found, that most electron velocity distribution functions are not alone Maxwellian. One of the reasons therefore is electron cyclotron resonance heating, which was used for ionizing and heating the plasma and what produces a suprathermal tail. It is possible, however, to obtain effective electron temperatures. These effective electron temperatures range from about 10 eV , what is similar to the electron bulk temperature, to more than 150 eV. / text

A need exists to obtain accurate, reliable and valid data to assess the external and internal loads of soccer matches, especially as it relates to South African soccer teams. Consequently, the objectives of this study were firstly to determine the fatigue rates and patterns of a cohort of university-level soccer players during matches when using global positioning system (GPS) to quantify the high-intensity running performances in rolling 5-min periods. Secondly, to determine the influence of Yo-Yo intermittent recovery test level 1 (Yo- Yo IR1) determined training status of a cohort of university-level soccer players on fatigue patterns and rate during match play. Thirdly, to determine the positional-internal match loads of a cohort of university-level soccer players by making use of heart rates and the Yo-Yo IR1-determined threshold values. Lastly, to compare the match analysis results of different methods aimed at determining the external and internal match loads of a cohort of university-level soccer players. Selected groups of university-level soccer players (n = 10–13) were required to complete a 40-m maximum speed test and the Yo-Yo IR1 during a two-week period either before or after each analysed match. The heart rate (HR) values and GPS data of each player were recorded during league soccer matches. For the first and second objectives of the study players were categorised into three activity level categories (low, moderate and high) according to their activity levels of the first half of the match. Furthermore, their high-intensity running (> 3.7m/s) (HIR) was monitored in rolling 5-min periods. The low-activity group showed a small to moderate difference (p <0.05) in high-intensity running (HIR) at 5-min and 15-min after the peak period compared to the average 5-min period. The moderate-activity group showed a moderate difference (p <0.05) in HIR at 5-min after the peak period. The high-activity group showed moderate to large declines in distance covered between the first 15-min of the second half (103.9 m/min) compared to the first 15-min of the first half (122.5 m/min). They also showed small to moderate declines in HIR during the first 10-min of the second half (25.7 m/min) compared to the first half (34.1 m/min). The low-activity group showed a small decline in distance covered during the first 5-min of the second half (76.3 m/min) compared to the first half (87.7 m/min). Conversely the low-activity group showed a small to moderate increase in distance covered during the last 10-min of the second half (95.7 m/min) compared to the first half (84.4 m/min). The Yo-Yo IR1 was not significantly correlated with any of the variables associated with HIR. For the third objective of the study players’ heart rates that corresponded with the first and second ventilatory thresholds as obtained during a Yo-Yo IR1 were used to classify heart rates into low (LI HR zone), moderate (MI HR zone) and high-intensity zones (HI HR zone). Results showed that attackers spent more time in the LI HR zone (3386 s; 62%; p <0.05) than defenders (2155 s; 40%) and midfielders (2425 s; 42%). The attackers spent less time in the HI HR zone (260 s; 4%; p <0.05) than the defenders (964 s; 15%). Midfielders (2444 s; 44%) and defenders (2364 s; 41%) spent more time in the MI HR zone than attackers (1854 s; 44%). For the fourth objective of the study players’ individualised velocity and heart rate (HR) thresholds were determined from the 40-m maximum speed test and the Yo-Yo IR1. Results showed a large (r = 0.5; p ≤0.01) correlation between the time spent in the LIVZ (5017 ± 368 s) and the LI HR zone (2891 ± 1086 s), with the true correlation value that varied between moderate and large. Similarly, a moderate (r = 0.3; p ≤0.01) to large (r = 0.6; p ≤0.01) correlation was found between the relative (11.4 ± 3.7%) and absolute time (669 ± 223 s) spent in the MIVZ and the MI HR zone (41.0 ± 16.8% and 2253 ± 752 s). However, the true correlation value for the absolute time spent in the MI zone fell between the large to very large category, whereas the correlation for the relative time was small to moderate. There were no significant correlations (p ≤0.01) between the HIVZ and the HI HR zone. Although some correlations were found from the Spearman’s rank correlation, when adjusting for 2max O V• and Yo-Yo IR1 performance these correlations became non-significant. From these study results it is clear that the Yo-Yo IR1 and 40-m speed test show promise to be used as valid sports-specific field tests for determining ventilatory thresholds for each player, the heart rates that correspond to these thresholds and the different velocity thresholds. The authors therefore recommend that researchers use these methods in future to determine individualised HR and velocity zones in combination with the GPS analysis results to define both the internal and external match loads of soccer players. Results of these analyses could enable future coaches and sport scientists to develop match-specific conditioning programs that reflect both the internal and external demands of soccer matches / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2015

A need exists to obtain accurate, reliable and valid data to assess the external and internal loads of soccer matches, especially as it relates to South African soccer teams. Consequently, the objectives of this study were firstly to determine the fatigue rates and patterns of a cohort of university-level soccer players during matches when using global positioning system (GPS) to quantify the high-intensity running performances in rolling 5-min periods. Secondly, to determine the influence of Yo-Yo intermittent recovery test level 1 (Yo- Yo IR1) determined training status of a cohort of university-level soccer players on fatigue patterns and rate during match play. Thirdly, to determine the positional-internal match loads of a cohort of university-level soccer players by making use of heart rates and the Yo-Yo IR1-determined threshold values. Lastly, to compare the match analysis results of different methods aimed at determining the external and internal match loads of a cohort of university-level soccer players. Selected groups of university-level soccer players (n = 10–13) were required to complete a 40-m maximum speed test and the Yo-Yo IR1 during a two-week period either before or after each analysed match. The heart rate (HR) values and GPS data of each player were recorded during league soccer matches. For the first and second objectives of the study players were categorised into three activity level categories (low, moderate and high) according to their activity levels of the first half of the match. Furthermore, their high-intensity running (> 3.7m/s) (HIR) was monitored in rolling 5-min periods. The low-activity group showed a small to moderate difference (p <0.05) in high-intensity running (HIR) at 5-min and 15-min after the peak period compared to the average 5-min period. The moderate-activity group showed a moderate difference (p <0.05) in HIR at 5-min after the peak period. The high-activity group showed moderate to large declines in distance covered between the first 15-min of the second half (103.9 m/min) compared to the first 15-min of the first half (122.5 m/min). They also showed small to moderate declines in HIR during the first 10-min of the second half (25.7 m/min) compared to the first half (34.1 m/min). The low-activity group showed a small decline in distance covered during the first 5-min of the second half (76.3 m/min) compared to the first half (87.7 m/min). Conversely the low-activity group showed a small to moderate increase in distance covered during the last 10-min of the second half (95.7 m/min) compared to the first half (84.4 m/min). The Yo-Yo IR1 was not significantly correlated with any of the variables associated with HIR. For the third objective of the study players’ heart rates that corresponded with the first and second ventilatory thresholds as obtained during a Yo-Yo IR1 were used to classify heart rates into low (LI HR zone), moderate (MI HR zone) and high-intensity zones (HI HR zone). Results showed that attackers spent more time in the LI HR zone (3386 s; 62%; p <0.05) than defenders (2155 s; 40%) and midfielders (2425 s; 42%). The attackers spent less time in the HI HR zone (260 s; 4%; p <0.05) than the defenders (964 s; 15%). Midfielders (2444 s; 44%) and defenders (2364 s; 41%) spent more time in the MI HR zone than attackers (1854 s; 44%). For the fourth objective of the study players’ individualised velocity and heart rate (HR) thresholds were determined from the 40-m maximum speed test and the Yo-Yo IR1. Results showed a large (r = 0.5; p ≤0.01) correlation between the time spent in the LIVZ (5017 ± 368 s) and the LI HR zone (2891 ± 1086 s), with the true correlation value that varied between moderate and large. Similarly, a moderate (r = 0.3; p ≤0.01) to large (r = 0.6; p ≤0.01) correlation was found between the relative (11.4 ± 3.7%) and absolute time (669 ± 223 s) spent in the MIVZ and the MI HR zone (41.0 ± 16.8% and 2253 ± 752 s). However, the true correlation value for the absolute time spent in the MI zone fell between the large to very large category, whereas the correlation for the relative time was small to moderate. There were no significant correlations (p ≤0.01) between the HIVZ and the HI HR zone. Although some correlations were found from the Spearman’s rank correlation, when adjusting for 2max O V• and Yo-Yo IR1 performance these correlations became non-significant. From these study results it is clear that the Yo-Yo IR1 and 40-m speed test show promise to be used as valid sports-specific field tests for determining ventilatory thresholds for each player, the heart rates that correspond to these thresholds and the different velocity thresholds. The authors therefore recommend that researchers use these methods in future to determine individualised HR and velocity zones in combination with the GPS analysis results to define both the internal and external match loads of soccer players. Results of these analyses could enable future coaches and sport scientists to develop match-specific conditioning programs that reflect both the internal and external demands of soccer matches / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2015