Grasslands throughout the world including those in British Columbia have been severely reduced and altered by agricultural production and inappropriate livestock grazing practices. Ongoing degradation of rangelands is a worldwide problem, currently affecting about 680 million hectares of rangelands. Studies on development and application of criteria and indicators for forests and grasslands are often lacking, or have been done on a limited number of sites with relatively narrow ranges of climate and soil type. This study aims to (i) quantify the relationships among soil/vegetation properties known to be affected by grazing to easily-assessed indicators, used in the existing health assessment systems, that do not require laboratory analyses or time consuming measurement, and (ii) to evaluate impacts of grazing on soil aggregate stability on the rough fescue grasslands of the southern interior of British Columbia. During the growing seasons of 2006 and 2007, soil and vegetation properties were measured on nine open grassland sites with a potential natural plant community dominated by rough fescue (Festuca campestris Rydb.) in the southern interior of British Columbia. Each site had at least one area excluded from grazing and all units were classified into different seral stages according to the amount of rough fescue present on the land. Rough fescue cover was found to be a useful indicator of the presence of functioning recovery mechanisms. Percent exposed mineral soil was found to be a sensitive indicator of the degree of soil stability and watershed function, as well as an indicator of the integrity of nutrient cycles and energy flows in rough fescue grasslands. Percent Junegrass cover was not as sensitive an indicator as percent exposed mineral soil, but has general overall strength with many health measures.. Only the 1-2 mm aggregate size class was closely related to most soil and vegetation properties, showing that it is more sensitive than the other aggregate stability parameters to soil and vegetation properties. The results from this study can help rangeland managers and ranchers in determining the rangeland health in their area as well as help researchers understand that only a certain number of parameters need to be assessed. / Land and Food Systems, Faculty of / Graduate

This thesis is dedicated to the derivation and the validation of a new collision model as a stabilization technique for high-order lattice Boltzmann methods (LBM). More specifically, it intends to stabilize simulations of: (1) isothermal and weakly compressible flows at high Reynolds numbers, and (2) fully compressible flows including discontinuities such as shock waves. The new collision model relies on an enhanced regularization step. The latter includes a recursive computation of nonequilibrium Hermite polynomial coefficients. These recursive formulas directly derive from the Chapman-Enskog expansion, and allow to properly filter out second- (and higher-) order nonhydrodynamic contributions in underresolved conditions. This approach is even more interesting since it is compatible with a very large number of velocity sets. This high-order LBM is first validated in the isothermal case, and for high-Reynolds number flows. The coupling with a shock-capturing technique allows to further extend its validity domain to the simulation of fully compressible flows including shockwaves. The present work ends with the linear stability analysis(LSA) of the new approach, in the isothermal case. This leads to a proper quantification of the impact induced by each discretization (velocity and numerical) on the spectral properties of the related set of equations. The LSA of the recursive regularized LBM finally confirms the drastic stability gain obtained with this new approach.

Abstract Study was made of host-guest complexation of neutral crown ethers with five- and six-membered N-heteroaromatic cations and purinium cation. Complexation of tetraphenylborate with selected N-heteroaromatic cations and tropylium cation also was studied. Crown ether complexes were characterized by mass spectrometric and 1H NMR spectrometric methods and by X-ray crystallography. Fast atom bombardment mass spectrometry (FABMS) was used as a prelimary tool to characterize the complexes and electrospray ionization mass spectrometry (ESIMS) was used to confirm the complexation stoichiometry. Crystal structures were determined by X-ray crystallography to study the complexation in solid state, and stability constants were measured in acetonitrile by 1H NMR titration at 30 °C to study the complexation in solution. Mass spectrometric studies indicated preferential 1:1 complexation stoichiometry between crown ethers and N-heteroaromatic cations. Crystal structures of crown ether complexes showed that hydrogen bonding and to a lesser degree cation-π and π-π interactions stabilize the structures in solid state. The values of stability constants for crown ether complexes with N-heteroaromatic cations and purinium cation varied between 10 and 350 M-1. Stability constants were higher for complexes with six-membered N-heteroaromatic cations and purinium cation than for complexes with five-membered cations. The values indicated that hydrogen bonding was the main interaction in solution. Tetraphenylborate formed complexes with four N-heteroaromatic cations and tropylium cation, and reacted with six N-heteroaromatic cations through the displacement of one phenyl group by N-heterocycle to form triphenylboranes. The complexes and displacement products were characterized by 1H NMR spectrometry. Four crystal structures of complexes and three crystal structures of displacement products were resolved. Stability constants of complexes were measured in methanol/acetonitrile (1:1) solution at 30 °C by 1H NMR titration method. The values of stability constants for tetraphenylborate complexes with N-heteroaromatic cations ranged from 10 to 50 M-1. C-H···π and N-H···π interactions were found to stabilize the structures both in solid state and in solution.

Class of 2015 Abstract / Objectives: To determine if a change in the amount of sodium bicarbonate (NaHCO3) in 5 different IV solutions will help prevent phenytoin from falling out of solution (i.e. precipitating). Our working hypothesis is that the stability of the phenytoin solution will change with different IV solutions and will increase with increasing the amount of sodium bicarbonate. Methods: A constant amount of phenytoin injection solution was mixed with a constant amount of one IV solution per beaker. Different amounts of alkalizing agents were then added to each phenytoin and IV mixture. Precipitation of the mixtures was observed every 30 minutes for 4 hours, then again in 24 hours. Results: When different IV solutions were added to the phenytoin and alkalizing agent mixture , the pH of the mixture dropped from 10 to 9 independent of the amount of alkalizing agent present in the mixture. All phenytoin mixtures precipitated within 60 minutes; 0.9% NaCl and phenytoin mixture being the one with the most delayed precipitation. Conclusions: Based on the result of this experiment, we rejected both of our specific aim hypotheses. Our hypothesis is rejected because the stability of the phenytoin solution will not change by using different IV solutions or by changing the amount of sodium bicarbonate.

M.Ing. (Electrical Engineering) / Induction heating has been used in practice for many years. The main goal of this study is to investigate the use of a single-turn coil in a typical induction heater. The work starts off with a background study of elecrroheat and specifically high-frequency induction heating. Finite element simulations were conducted on different coil shapes and compared with each other. The converter. with control and driver circuits. used in the, experimental setup, as well as the experimental construction and results are described. The work is concluded with an evaluation of the project.

In order to achieve the ambitious decarbonisation targets of the UK government, up to 30GW of wind generation could be connected to the GB transmission system by 2020. The challenges imposed when incorporating this volume of renewable energy are significant, introducing new technical challenges for National Grid as the system operator for the Great Britain transmission system. The majority of this new renewable generation will be connecting in Scotland and offshore in the UK as a whole. This results in greater uncertainty in the system from significant changes to the direction and volume of power flows across the network. In addition this implies a higher power transfer capacity requirement on the AC transmission lines, which are currently stability-limited, connecting SPT (Scottish Power Transmission) and National Grid networks. The required power transfer capability increases every year because of the large-scale increase in wind generation. Therefore, there is insufficient transmission capacity in the existing network to accommodate the increasing power transfer without constraining output of some generation plants. A range of new state of art technologies such as embedded HVDC link and Thyristor Controlled Series Compensation (TCSC) are planned to be added to the GB system in order to provide additional capacity and consequently facilitate the integration of large-scale renewable generation. It is, therefore essential that National Grid explores new ways of operating the transmission network and new devices to gain additional benefit from the HVDC link and the TCSC capabilities with regard to the system stability enhancement. This thesis investigates the effectiveness of the HVDC link and the TCSC with a view to system stability enhancement. A hierarchical stability control system to enhance the stability limit and achieve the best transient and dynamic performance using the HVDC link and the TCSCs as actuators in the feedback control system is proposed. In addition, a stability control system, using a robust and stabilising Sample Regulator multivariable control design method , to guarantee the system robustness and stability is proposed and designed. The performance and capability of the designed controller in co-ordinated control of the forthcoming power flow control devices are demonstrated on benchmark networks as well as full dynamic models of the GB transmission system using various study cases. Finally, the effectiveness of the West Coast HVDC link in improving the inter-area oscillation damping is presented using the developed model of the future GB transmission system.

Doctor of Philosophy / Department of Animal Sciences and Industry / John M. Gonzalez / American beef producers use a multitude of production regimens, with new products constantly becoming available to producers that could ultimately produce beef that fits niche markets. Additionally, U.S. producers employ the use of two exogenous growth promotants (ExGP), anabolic implants and β-adrenergic agonists, to maximize production efficiency. This body of work examined effects of different production strategies on beef quality. In the first study, steers were fed a conventional diet or a diet containing two supplements of the Programmed Nutrition Beef Program (PN) and each diet was fed with or without ExGP. There were no adverse effects on color, but use of ExGP negatively impacted tenderness of steaks. However, the inclusion of the PN supplements decreased purge loss of loins during aging and decreased cook loss of beef steaks. The decrease in purge and cook loss may be intriguing for retailer who purchase-in and cook products as they could specify a demand for beef from animals in this program to potentially save on product losses. Researchers have examined strategies to increase omega-3 fatty acids within beef, as omega-3 fatty acids are health beneficial. The second study examined impacts of feeding increasing levels of a docosahexaenoic acid (DHA)-rich microalgae to heifers on fatty acid profiles, color stability, and palatability of the LM and color and . Feeding increasing levels of microalgae meal quadratically increased total omega-3 PUFA, with increases in DHA content up to 850% and eicosapentaenoic acid (EPA) up to 340% at the greatest feeding level. Although feeding microalgae changed fatty acid profiles to be more health beneficial, color and flavor were adversely affected. At the end of display, steaks from heifers fed the greatest amount of microalgae had reduced a* (redness) values and increases in surface metmyoglobin (discoloration) formation. Panelists detected more off-flavors as the level of microalgae meal increased in the diet. Poor color stability and increases in off-flavors were due to increased oxidation products in these steaks, but problems could be mitigated by inclusion of antioxidants in the diet. The third study presented examined effects of feeding antioxidants to steers fed microalgae meal on color and palatability of Longissimus lumborum steaks. Steers were fed vitamin E at a level over their nutritional need and a selenium-yeast product in addition to feeding microalgae. Again, feeding microalgae without antioxidants in the diet negatively impacted color during display, but feeding antioxidants significantly improved the color stability. There were no off-flavor differences between steaks from steers fed the diet containing only microalgae and diet containing microalgae with antioxidants. Increasing the antioxidant content of the finishing diet when microalgae was fed is feasible way to increase the color stability of steaks and decrease off-flavors of Longissimus lumborum steaks.

Magister Economicae - MEcon / The transmission mechanism of monetary policy has generated a substantial amount of interest in economic research in many countries, with most studies focusing on how a change in monetary policy stance, usually defined as an exogenous shock in a short-term interest rate, affects the economy at a national level, with changes in output, inflation and exchange rates being the key variables under investigation. This study adopts a similar analysis, with the general objective of examining the effectiveness of monetary policy in Botswana. Specifically, this study aims at finding out how the central bank rate affects inflation in Botswana and the duration of its effects on economic variables in Botswana. The study adopts the recursive VAR methodology, using quarterly data from 1995 quarter one to 2009 quarter four. The results show that monetary policy is most effective via the interest rate channel in Botswana, followed by the credit channel and then the exchange rate channel. In addition, the results reflect that the economy reacts to monetary policy actions with a one period lag, with the effect lasting for seven quarters.

A teleoperation system is a master-slave robotic system in which the master and slave robots are at different geographical locations and synchronize their motions through the communication channel, with the goal of enabling the human operator to interact with a remote environment. The two primary objectives of bilateral teleoperation systems, position tracking and force feedback, are necessary for providing the user with high fidelity telepresence. However, time delays in communication channels impede the realization of the two objectives and even destabilize the system. To guarantee stability and improve performance, several damping injection-based controllers have been developed in this thesis for two channel and four channel teleoperation systems. For two channel teleoperation, an adaptive bounded state feedback controller has firstly been proposed to address teleoperation with time-varying delays, model uncertainties and bounded actuations. Next, a simplified and augmented globally exponentially convergent velocity observer has been designed and incorporated in the conventional P+d control to obtain stable bilateral teleoperation without using velocity measurements. Then, the more challenging bounded output feedback control problem has been solved by combining the bounded state feedback control and output feedback control two techniques with more conservative control gains. In four channel teleoperation, a hybrid damping and stiffness adjustment strategy has been introduced to tightly constrain the master and slave robots and achieve robust stability. Further, the nonsingular version is developed to conquer the singularity problem in the hybrid strategy, which has been proved to avoid unexpected torque spikes due to the singularity problem at zero velocities. Besides, this thesis has also provided a reduced-order controller to guarantee position coordination for arbitrarily large position errors and maintain the tight coupling between the master and slave sites. After concluding all the research results, future study directions are pointed out at the end of this thesis. / Graduate

Determination of rumen escape of rumen protected nutrients is needed to accurately assess the amount of nutrients that can be absorbed and utilised from the intestinal tract of dairy cows. This assessment allows more precise feeding of specific nutrients, thereby increasing metabolic efficiency and reducing production of animal wastes. The currently used method of choice to determine the rumen escape of rumen protected nutrients is ruminal in situ evaluation, which cannot measure actual rumen escape, as the experimentalist can only estimate the rate at which a rumen protected product (RPP) will exit the rumen. The two-part objective of the study was to use an in vivo dual liquid phase marker system to determine ruminal stability of RPP and to determine the stability of the three RPP, as well as determine the best in sacco incubation time to match the determined stability. Four multiparous, ruminally cannulated, lactating Jersey cows [body weight 384 kg ± 28.0 kg, milk yield 24 ± 4.0 L, days in milk 69 ± 42 d, parity 4.5 ± 1.29 (mean ± standard deviation)] were used in a 4 x 4 Latin square design. Cows were assigned to one of four groups with one group being the control group and the other three each receiving a different RPP. The study was composed of four 14 d periods with a 10 d adaptation period before the start of the study to allow the cows to adjust to the individual stalls, diets and conditions. Days 1-6 of each period were for recovery/ rest, days 7-8 for an in sacco measurement to determine the stability of the RPP, days 8-11 for pH logging, and days 11-14 to determine the in vivo stability of the RPP. Cows were fed ad libitum a common total mixed ration (TMR) composed of chopped lucerne hay, maize stover, maize meal, soybean oilcake, hominy chop, molasses, urea, rumen inert fat and a vitamin/mineral premix containing 180 g/kg crude protein, 317 g/kg neutral detergent fibre and 213 g/kg starch on a dry matter basis. Cows were fed twice daily at 2 kg above their daily voluntary feed intake level and kept in individual stalls of 6 x 6 m with wood chips on the floor as bedding. The three RPP were: RP Ascorbic Acid (A), RP Lysine (L) and RP Niacin (N). The RP A and RP N were both composed of 623 g/kg nutrient (Ascorbic acid/ Niacin respectively), 89 g/kg Co-EDTA and 288 g/kg fat matrix, with a measured specific gravity of 1.21. The RP Lysine was composed of 518.7 g/kg Lysine, 86.5 g/kg of Co- EDTA and 394.8 g/kg fat matrix, with a measured specific gravity of 1.21. The fat matrix used in all the RPP’s was the same. The method used in this study aimed to create an accurate quantitative value of true ruminal stability, which traditional methods lack. Stability of the RPP was measured as the proportion of the area under the curve from the ruminal clearance of Co (included in the RPP as Co-EDTA) relative to the clearance of the Cr (as free Cr-EDTA). In sacco measures consisted of insertion of six Dacron bags into each treatment cow (i.e. A, L, N), with each Dacron bag containing 5 g of the relevant product and each cow receiving a different product. Two bags were collected after 12, 24 and 30 h of incubation and then weighed back to determine the stability of the RPP as well as disappearance of the RPP over the 30 h period. Ruminal pH logging occurred directly after and the pH loggers were left in the rumens for 48 h to measure pH every 10 min in each cow. During in vivo measurements each cow was dosed simultaneously with 150 g of the relevant RPP (calculated to contain 15g Co-EDTA) as well as 16.679 g of Cr-EDTA (Control group was dosed with 16.679 g Cr-EDTA and 15 g Co-EDTA) calculated to deliver 2.4 g of Co and 2.4 g of Cr respectively, into the rumen of each cow. Pre-dosing rumen fluid samples were collected and samples were then collected, starting one hour post dosing, every 2 h through 25 h post-dosing, then every 4 h until 49 h post dosing, and thereafter every 6 h until 73 h post dosing. These samples were analyzed for Co, Cr and pH. Samples were also collected every 6 h throughout the 74 h test period for nitrogen ammonia and volatile fatty acid analysis. Rumen pH was within normal ranges and showed normal diurnal variations during sampling. Ruminal pH was unaffected by in vivo treatment and averaged 5.88, with a diurnal variation between 5.65 and 6.40. Animal performance was unaffected by treatment with average milk production of 24.6 L/ day, milk fat of 41.8 g/ kg and milk crude protein of 35.6 g/ kg. The rumen stability of the RPP differed, despite having the same fat matrix, presumably due to differences in the chemical interactions of the nutrients with the fat cover; for example lysine is known to be more reactive. The rumen stability of RP Niacin was the highest (p = 0.06) at 66.7% relative to RP Lysine at 55.0%, with RP Ascorbic acid at 58.7%. In sacco incubations of the RPP showed variation in results. This in vivo method can be utilised to quantitate rumen stability of RPP, although it can not indicate the most appropriate rumen in sacco incubation time to reflect that measurement. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted