The majority of patients with chronic obstructive pulmonary disease (COPD) have milder airway obstruction and are not diagnosed in a timely fashion. Nevertheless, these patients are largely under-studied; this, despite new evidence of increased morbidity and mortality in this sub-population. Recent studies have highlighted the increased ventilatory requirements and abnormalities in respiratory mechanics as important features to explain the relatively reduced exercise tolerance and greater exertional dyspnea in these patients. However, it remains uncertain whether such abnormal mechanical factors actually limit exercise capacity in mild COPD. Accordingly, the objective of this study was to determine whether ventilatory constraints represent a primary factor in exercise limitation and increased dyspnea in this patient group. To determine the role of mechanical factors in exercise limitation in mild COPD, we selectively loaded the respiratory system by adding dead space (DS) to the breathing circuit. We compared ventilation, breathing pattern, operating lung volumes, and dyspnea intensity during incremental cycle exercise in 20 patients with GOLD stage I COPD (post-bronchodilator FEV1/FVC=61±5%, and FEV1=95±11% predicted; mean±SD) and 20 healthy age-, sex- and BMI-matched subjects under two conditions, in randomized order: unloaded control (CTRL) or ventilatory stimulation by 600mL of an added DS. Compared to the CTRL condition, both healthy and COPD participants had small decreases in peak work rate and no significant increase in peak ventilation with the added DS. At the highest equivalent work rate of 60 watts, DS caused a smaller increase in tidal volume (VT) in COPD compared with healthy subjects (+0.26±0.29 vs. +0.56±0.22 L respectively, p<0.01) with a correspondingly greater increase in dyspnea intensity (+1.8±1.8 vs. +0.2±0.6 Borg units, respectively, p<0.0001). At peak exercise, COPD patients failed to significantly increase VT, reflecting the fact that end-inspiratory lung volume (EILV) could not increase with DS vs. CTRL (5.25±0.91 vs. 5.16±0.84 L, respectively, p=0.41). This contrasts the results in health where EILV increased with DS vs. CTRL (5.40±1.01 vs. 5.13±0.90 L, respectively, p<0.05). We conclude that the lower exercise performance in mild COPD, compared with health, is explained by critical respiratory mechanical constraints which limit further increases in ventilation to support a higher metabolic load. / Thesis (Master, Physiology) -- Queen's University, 2012-09-28 12:04:50.507

No description available.

<p><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">The most significant human impacts on the hydrological system are due to land-use change. The conversion of land to agricultural, mining, industrial, or residential uses significantly alters the hydrological characteristics of the land surface and modifies pathways and rates of water flow. If this occurs over large or critical areas of a catchment, it can have significant short and long-term impacts, on the quality of water. While there are methods available to quantify the pollutants in surface water, methods of linking non-point source pollution to water quality at catchment scale are lacking. Therefore, the research presented in this thesis investigated modelling techniques to estimate the effect of land-cover type on water quality. The main goal of the study was to contribute towards improving the understanding of how different land-covers in an urbanizing catchment affect surface water quality. The aim of the research presented in this thesis was to explain how the quality of surface runoff varies on different land-cover types and to provide guidelines for minimizing water pollution that may be occurring in the Kuils-Eerste River catchment. The research objectives were / (1) to establish types and spatial distribution of land-cover types within the Kuils-Eerste River catchment, (2) to establish water quality characteristics of surface runoff from specific land-cover types at the experimental plot level, (3) to establish the contribution of each land-cover type to pollutant loads at the catchment scale.<span style="mso-spacerun:yes"> </span><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">Land-cover characteristics and water quality were investigated using GIS and Remote Sensing tools. The application of these tools resulted in the development of a land-cover map with 36 land classifications covering the whole catchment. Land-cover in the catchment is predominantly agricultural with vineyards and grassland covering the northern section of the catchment. Vineyards occupy over 35% of the total area followed by fynbos (indigenous vegetation) (12.5 %), open hard rock area (5.8 %), riparian forest (5.2 %), mountain forest<span style="mso-spacerun:yes">&nbsp / &nbsp / </span>(5 %), dense scrub (4.4 %), and improved grassland (3.6 %). The residential area covers about 14 %. Roads cover 3.4 % of the total area. </span><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">Surface runoff is responsible for the transportation of large quantities of pollutants that affect the quality of water in the Kuils-Eerste River catchment. The different land-cover types and the distribution and concentration levels of the pollutants are not uniform. Experimental work was conducted at plot scale to understand whether land-cover types differed in their contributions to the concentration of water quality attributes emerging from them.<span style="color:black"> Four plots each with a length of 10 m to 12 m and 5 m width were set up. Plot I was set up on open grassland, Plot II represented the vineyards, Plot III covered the mountain forests, and Plot IV represented the fynbos land-cover.</span> Soil samples analyzed from the experimental plots fell in the category of sandy soil (Sa) with the top layer of Plot IV (fynbos) having loamy sand (LmSa). The soil particle sizes range between fine sand (59.1 % and 78.9 %) to coarse sand (between 7 % and 22 %). The content of clay and silt was between 0.2 % and 2.4 %. Medium sand was between 10.7 % and 17.6 %. In terms of vertical distribution of the particle sizes, a general decrease with respect to the size of particles was noted from the top layer (15 cm) to the bottom layer (30 cm) for all categories of the particle sizes. There was variation in particle size with depth and location within the experimental plots.</span><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">Two primary methods of collecting water samples were used / grab sampling and composite sampling. The quality of water as represented by the samples collected during storm events during the rainfall season of 2006 and 2007 was<span style="mso-spacerun:yes">&nbsp / </span>used to establish <span style="mso-spacerun:yes">&nbsp / </span>water quality characteristics for the different land-cover types. The concentration of total average suspended solids was highest in the following land-cover types, cemeteries (5.06 mg L^-1), arterial roads/main roads (3.94 mg L^-1), low density residential informal squatter camps (3.21 mg L^-1) and medium density residential informal townships (3.21 mg L^-1). Chloride concentrations were high on the following land-cover types, recreation grass/ golf course (2.61 mg L^-1), open area/barren land (1.59 mg L^-1), and improved grassland/vegetation crop (1.57 mg L^-1). The event mean concentration (EMC) values for NO₃-N were high on commercial mercantile (6 mg L^-1) and water channel (5 mg L^-1). The total phosphorus concentration mean values recorded high values on improved grassland/vegetation crop (3.78 mg L^-1), medium density residential informal townships (3mgL^-1) and low density residential informal squatter camps (3 mg L^-1). Surface runoff may also contribute soil particles into rivers during rainfall events, particularly from areas of disturbed soil, for example areas where market gardening is taking place. The study found that different land cover types contributed differently to nonpoint source pollution. </span><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">A GIS model was used to estimate the diffuse pollution of five pollutants (chloride, phosphorus, TSS, nitrogen and NO₃-N) in response to land cover variation using water quality data. The GIS model linked land cover information to diffuse nutrient signatures in response to surface runoff using the Curve Number method and EMC data were developed. Two models (RINSPE and N-SPECT) were used to estimate nonpoint source pollution using various GIS databases. The outputs from the GIS-based model were compared with recommended water quality standards. It was found that the RINSPE model gave accurate results in cases where NPS pollution dominate the total pollutant inputs over a given land cover type. However, the N-SPECT model simulations were too uncertain in cases where there were large numbers of land cover types with diverse NPS pollution load. All land-cover types with concentration values above the recommended national water quality standard were considered as areas that needed measures to mitigate the adverse effects of nonpoint pollution. </span><span lang="EN-GB" style="font-size: 12.0pt / line-height:150% / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / ">The expansion of urban areas and agricultural land has a direct effect on land cover types within the catchment. 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It is expected that South Africa will have to construct as much generating capacity in the next five years as has been constructed over the past 50 years. Industrialization and urbanization dictates that the larger portion of this increase will be required in the supply areas under the control of Municipal Electricity Undertakings, which means that these undertakings will have to anticipate rapid growth in their infrastructures. This will put a tremendous strain on their resources of revenue, materials and labour, and it is obvious that comprehensive and co-ordinated policies are required to be developed to enable these undertakings to deliver the electrical energy to the final consumers at the lowest possible cost. The Electricity Undertaking is a business organization with unusually difficult managerial problems in all its functional areas. Its personnel are adversely affected by the vast area of supply and by the resulting difficulty of direct supervision and control. The capital cost of electrical equipment is high, and there may be a tendency to reduce the initial cost by ignoring the long term costs associated with the selection of equipment. Electricity pricing is very difficult, as electricity is not a uniform product. The consumption patterns of the consumers causes severe peaking of loads to occur, resulting in very low utilization )f the capital equipment involved, and which can threaten to overload existing networks. These problems are compounded by the fact that the undertaking is a monopoly and as such is not driven by the free-market motivating forces, such as a profit motive and the constant need to improve to meet competition. There is thus no motive to seek optimum solutions to the many problems. It is shown that the Load Factor is an indication of the efficient use of scarce resources, and that it is similar to measurements of profitability, such as Return-on-Investment, etc. It is therefore possible to replace the missing drive for profit and product improvement by the need to constantly improve the load factor. By making this the main objective of the undertaking many of the stated problems are put in their correct perspective. Maintenance becomes important, as power failures adversely affect the load factor. More care is exercised in equipment selection, as long term energy losses are taken into account. Electricity pricing and its effect on consumer consumption patterns becomes important. The concerted effort to improve the load factor is referred to as load management. Due to the tremendous increase in electricity consumption which is expected over the next decade it is certain that load management will play an ever increasing role. Load Management is defined as the sustained attempt at modifying the load curve. Soft load management refers to pricing policies and incentive schemes designed to induce users to shift their loads .out of the peak periods. Hard load management physically switches customer loads. This thesis examines the results obtainable from various methods of load management including off-peak incentive tariffs, on-peak-reduction rebates, the use of current limiters, peak load reduction by means of voltage reduction and remote control of water heater cylinders. It is shown that whereas Sasolburg saves around R7S0 000.00 p.a. and Randburg saves over Rl,5-million p.a.,other towns such as Pretoria and Pietermaritzburg find their geyser control systems ineffective, and are phasing them out. It has hitherto not been possible to determine the actual savings which would result from the installation of a geyser control system, or to determine the optimum number of controlled geysers. The result was that some undertakings would install a control system at considerable expense which resulted in minimal savings, while other towns forego the opportunity to save hundreds of thousands of rands in reduced demand charges. In this thesis, the author develops a feasibility study model which permits the system load curve to be analysed and the viability of a geyser control system to be determined. The model was tested against the controlled and uncontrolled load curves of Somerset West, and was found to be accurate. It was shown that a geyser control scheme is a very viable proposition for those undertakings where the feasibility study shows a contribution of more than 0,5 KVA per geyser towards peak load reduction. This forms the basic guideline for the selection of an appropriate form of load mangement, and guidelines are presented to develop supporting policies in all fields of the undertakings' functions. In order to facilitate correct decision-making and to assist in the development of comprehensive policies, a database of concepts and models is presented in the various fields and various misconceptions are dicussed. The guidelines have been applied by several electricity undertakings. By using the Feasibility Study Model it was shown that the proposed installation of 4000 geyser control units at Oudtshoorn, at a cost of over RI-million, was not viable. The Feasibility Study Model permits the savings to be calculated for different numbers of geysers and it was shown that the system saturates at about 1500 controlled geysers. By reduci ng the number of controlled geysers to around 1500 the installation cost will be reduced by about R500 000.00 and the system will show a net operating savings , " of RI05 540.00 in the first year, increasing as ESCOM increases its tariffs. The application of these principles conceivably prevented the needless expenditure of RI-million on a system that would have run at an operating loss of over R17 000.00 p.a. The feasibility study model was applied to the Stanger load curve to determine the correct selection of load management. The results indicate excellent response to geyser control, and showed that a system controlling 2500 geysers, costing R498 500.00 would show a gross savings of R297 000.00 in the first year, rising to RSI0 000.00 within 5 years if ESCOM increases its tariff by 10% p.a. Based on these results and recommendations the Department of Finance gave ad hoc approval to the Borough of Stanger for the additional expenditure in the current financial year to install the control equipment. The guidelines indicated a similar result for Tongaat, where the gross savings would be R360 000.00 in the first year, increasing to R637 680.00 within 5 years if ESCOM increases its tariff by 10% p.a. The estimated cost of the control equipment is R493 649.00. In complete contrast, the feasibility studies for geyser control undertaken on the Ballito load curve showed a contribution of less than 0,5 KVA per geyser, which indicated that the alternative forms of load management should be implemented. The results are contained in the case studies. / Thesis (DBA)-University of Durban-Westville, 1986.

Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.

No description available.

Stay-in-place (SIP) formwork has been used as an alternative to the conventional formwork system. The systems are mainly assembled on site, hence simplifying the construction process and reducing the construction time as the removal procedure has been eliminated. SIP formwork systems can be divided into two main categories; structural and non-structural formwork, based on their contribution to resist applied loads. The structural formwork provides the same advantages as the non-structural formwork, in addition to its contribution to resist the applied loads. As a result, the cross section and the reinforcement of the structural member can be reduced. Recently, polyvinyl chloride (PVC) has been used as a stay-in-place formwork because of its lower cost compared to other materials, durability, and ease to assemble. The PVC SIP formwork consists of interconnected elements; panels and connectors that serve as permanent formwork for the concrete walls. In this study, the behaviour of the PVC encased reinforced concrete walls under eccentric compression loading was investigated. The variables in this study were the type of the specimen (PVC encased or control), the longitudinal reinforcement (4-10M or 4-15M rebars) and the eccentricity of the applied compression load (33.87 mm, 67.73 mm and 101.6 mm). Generally, the control walls (without PVC encasement) failed by yielding of the steel followed by crushing of the concrete, or by crushing of the concrete without yielding of the steel. For the PVC encased walls, buckling of the PVC occurred after the concrete crushed. The PVC encased specimens showed a higher peak load than their peer control walls. The effect of the PVC on increasing the ultimate capacity at a given eccentricity was more significant for the walls reinforced with 4-10M than the walls reinforced with 4-15M. For the lowest reinforcement ratio (4-10M), the PVC encased specimens showed an increase in peak load by 37.2% and 17.1% at an eccentricity of 67.73 mm and 101.6 mm, respectively. When the reinforcement was increased to 4-15 M, the increase in the peak load dropped at all eccentricities to 10%. For the vertical and the mid-span deflection, the PVC encased specimens and the control specimens showed the same values. Also, the test results showed an increase in the energy absorption capacity for the PVC encased specimens compared to the controls specimens, where the effect for the walls reinforced with 4-10M was higher than the walls reinforced with 4-15M at a given eccentricity. An analytical model was developed to predict the ultimate load capacity of the specimens taking into consideration the effect of the PVC on the load carrying capacity of the walls. The provision was derived based on the moment magnification factor method in which the effect of secondary stresses associated with the column deformations was taken into consideration. The calculated capacities of the PVC encased specimens showed a conservative error of 5.9% on average.

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases.

Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases.