This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

At the opposite of numerous countries in the world, despite its natural assets and its enormous surface and underground water potential, Cameroon is still trying to put down effective policies for the supply of safe drinking water for its rural population. Many initiatives to supply these communities through a national water distribution network have remained for the most dead letters or fruitless. A very high number of people still endanger their life daily by relying on archaic water supply techniques – when they are working – and by consuming unsafe water. This study therefore investigates if fog and rainwater harvesting could help in securing safe drinking water to these same rural communities, leaving the remaining demand - if any - to be provided by the existing but too often non-reliable supply system. Two pilot sites have been selected for their different climatic conditions; a village in the mountainous Western Province and another in the low-lying area of the Far-North Province of Cameroon. Average climatic data and basic topographical information from each location were used to determine the size and number of required collectors. The potential monthly water-yield at each site was then assessed using an actual climatic data series (8 years) and the theoretical performance simulated based on an increasing per capita daily consumption (10 – 40 l.d-1). An estimate of implementation cost is provided as part of the discussion on the feasibility of using both fog and rainwater harvesting as low-cost approaches to securing safe drinking water in Cameroon.

Background: Coronary Artery Bypass Grafting (CABG) surgery is one of the most commonly performed surgical procedures to improve the symptoms of coronary artery disease. The Long Saphenous Vein (LSV) is typically used as a graft to bypass the blocked coronary arteries. The traditional way of harvesting the LSV is to make a long skin incision in the patient's leg. This technique has a high rate of incidence of wound complications and postoperative pain and poorer patient satisfaction. Endoscopic Vein Harvesting (EVH) techniques, introduced more than a decade ago, reduce these complications and improve quality of life. Findings regarding the safety and efficacy of EVH techniques and the quality of the vessel harvested by this technique are contradictory. Adoption of EVH techniques is still inconsistent globally and it is not completely accepted by all cardiac centres. Many studies are available in the literature measuring either histological outcome or clinical outcome in relation to different harvesting techniques. However, there remains no definitive randomised data available directly correlating harvesting-induced vein damage with clinical outcome. The aim of this Vein Integrity and Clinical Outcome (VICO) randomised trial was designed to assess the direct relationship between the histological damage caused during different methods of vein harvesting and clinical outcome post coronary artery bypass surgery. Methods: 100 patients were randomised in each group: Group 1 consists of closed tunnel CO2 endoscopic vein harvesting (EVH) (CT-EVH) and Group 2 consists of open tunnel CO2 EVH (OT-EVH) with the control Group 3 consists of standard open vein harvesting (OVH) with a total of 300 patients in this study. All the veins were harvested by an experienced practitioner who has performed &gt;2000 OVH and &gt;250 EVH. 1cm x 3 segments from three different parts of the vein were obtained for all patients (n=900). The histological levels of damage (endothelial and muscular layers) of the harvested vein and post clinical outcome for Major Adverse Cardiac Events (MACE) were measured using validated measuring tools. Health economic (cost effectiveness, EQ-5D) and health-related quality of life (SF-36) data were also recorded to assess the impact of these surgical techniques. Results: The level of endothelial disruption was greatest in the OT-EVH group in the proximal, distal and random samples (all p < 0.001). Internal muscle migration was greatest in OT-EVH compared to the other groups for proximal, distal and random samples (all p < 0.001). Smooth muscle circular layer detachment was observed on a much greater scale in the endoscopic groups compared to OVH in proximal (p=0.008), distal (p < 0.001) and random (p=0.001). Smooth muscle longitudinal layer detachment was consistent between groups in proximal (p=0.113) and distal (p=0.380) samples but was greater in endoscopic groups compared to OVH (p=0.012). Secondary clinical outcomes demonstrated no significant differences in composite MACE scores at 3, 6, 12, 18 and 24 months. The quality adjusted life in years (QALYs) gain per patient was: 0.11 (p < 0.001) for closed tunnel CO2 EVH and 0.07 (p=0.003) for open tunnel CO2 EVH compared with open vein harvesting. The likelihood of being cost-effective, at a pre-defined threshold of £20,000 per QALYs gained was: 75% for closed tunnel EVH, 19% for open tunnel EVH and 6% for open vein harvesting. Conclusion: In this study, open vein harvesting was associated with better preservation of vein layers in non-distended proximal samples than endoscopic vein harvesting. Both EVH groups displayed some degree of histological damage; OT-EVH was associated with more endothelial disruption. Clinical outcomes suggest that histological findings do not directly contribute to MACE outcomes. Gains in health status were observed and cost-effectiveness was better with CT-EVH compared with the other two surgical techniques. These results suggest that EVH can be utilised safely, but with careful selection of patients.

In many developing countries, the stress of rapidly growing populations, mismanagement of resources and changing climate has created a burden on already compromised water resources. In Africa, where a significant proportion of the population is without access to improved water source, the urgency for clean available water sources to sustain healthy and productive human and natural populations has become a priority. As a water scarce country, Kenya has seen an increased investment in rainwater harvesting (RWH) projects to harness the vastly untapped rainwater resource, particularly in rural areas. Most of RWH literature is centered on the potential and implementation of rainwater harvesting systems, however not much focus has been placed on examining the demand satisfaction of these systems. This study investigates the reliability of rooftop rainwater harvesting (RRWH) as a key priority source of water supply for domestic use in three towns in Western Kenya: Kisumu, Nakuru and Lodwar. This was done using two approaches (1) the fraction of time water was available and (2) the fraction of time that a minimum demand was met, with acceptable reliability of 0.95 or higher. Actual rainfall data and RRWH parameters were used to produce supply/demand simulations of the system under Constant-Demand and Responsive-Demand scenarios over ten years. It was observed that all towns achieved acceptable reliability values for RRWH in terms of water availability however Lodwar only achieved demand satisfaction below 0.95. This study concluded that though RRWH cannot satisfy the minimum demand requirement through all days of the year, it is more than able to provide an alternative water supply for the domestic household in periods of long dry spells or when primary water source are inadequate.

Presently, wireless sensor nodes are widely used and the lifetime of the system is becoming the biggest problem with using this technology. As more and more low power products have been used in WSN, energy harvesting technologies, based on their own characteristics, attract more and more attention in this area. But in order to design high energy efficiency, low cost and nearly perpetual lifetime micro energy harvesting system is still challenging. This thesis proposes a new way, by applying three factors of the system, which are the energy generation, the energy consumption and the power management strategy, into a theoretical model, to optimally design a highly efficient micro energy harvesting system in a real environment. In order to achieve this goal, three aspects of contributions, which are theoretically analysis an energy harvesting system, practically enhancing the system efficiency, and real system implementation, have been made. For the theoretically analysis, the generic architecture and the system design procedure have been proposed to guide system design. Based on the proposed system architecture, the theoretical analytical models of solar and thermal energy harvesting systems have been developed to evaluate the performance of the system before it being designed and implemented. Based on the model's findings, two approaches (MPPT based power conversion circuit and the power management subsystem) have been considered to practically increase the system efficiency. As this research has been funded by the two public projects, two energy harvesting systems (solar and thermal) powered wireless sensor nodes have been developed and implemented in the real environments based on the proposed work, although other energy sources are given passing treatment. The experimental results show that the two systems have been efficiently designed with the optimization of the system parameters by using the simulation model. The further experimental results, tested in the real environments, show that both systems can have nearly perpetual lifetime with high energy efficiency.

M.Ing. (Civil Engineering Science) / In recent years, there has been an international trend towards installing rainwater tanks in an attempt to save water. However, there are no clear guidelines for determining the optimal size of such a tank in South Africa. This study investigates the possibility of simplifying the process of sizing a rainwater tank for optimal results. It utilises daily data from four rainfall stations, namely Kimberley, Mossel Bay, Punda Maria and Rustenburg, obtained from the South African Weather Services. The water use is considered to be for indoor purposes only, therefore assuming a constant daily demand to be extracted from the tank. The required size of a rainwater tank is influenced by the MAP, the area of the roof draining into the tank, the water demand (both the average demand and seasonal variations), the desired reliability of supply, and the rainfall patterns. The first step in simplifying the process is to consolidate the above variables. The tank volume is expressed as the number of days it could supply the average daily water demand. Another variable is created which provides the ratio of the total water volume which could theoretically be harvested from the roof in an average year, to the total water demand, from the tank, for a year. This has the effect of consolidating the MAP, the roof area, the water demand and the tank volume into two variables only and eliminates the need to consider numerous demand values. Using simulations over 16 years for each location, the relationships between these variables were determined to ensure 90%, 95% and 98% assurance of supply.

Vibration energy harvesting has been widely investigated by academia and industry in the past decade with focus on developing distributed power sources. One of the prime goals of energy harvesters is to provide power to wireless sensors allowing for the placement of these sensors in the remote and inaccessible areas where battery is not an option. Electromechanical modeling approaches have been developed for enhancing the mechanical to electrical conversion efficiencies utilizing electromagnetic, piezoelectric, and magnetostrictive mechanisms. Models based upon the constitutive equations for these three conversion mechanisms, supported by extensive experimental results available in literature, suggest that power requirement through energy harvesters can be met only when the total volume is in the range of 1-100 cm3. There exists a critical volume of 0.5 cm³ at which above which the electromagnetic mechanism exhibits higher power density as compared to the other mechanisms. Therefore, in this thesis electromagnetic energy conversion was adopted to develop high power energy harvesters. We also present a novel vibration energy harvesting method which rivals the power density and bandwidth of the traditional methods. The overarching theme throughout the design process was selecting the structure and fabrication methodology that facilitates the transition of the technology. The experimental models were characterized at accelerations and frequencies typically found in the environmental vibration sources. The thesis provides in-depth the design, modeling, and characterization of a vibration energy harvester which creates relative motion differently than the conventional harvesters. Conventional designs rely on amplifying the original source displacement operating at the resonance condition. In the harvester design proposed in this thesis, the relative motion is created by cancelling the vibration at one location and transferring the source vibration directly to another location by combining a vibration isolator with a vibration absorber. In this novel configuration, termed as Direct Vibration Harvester (DVH), the energy is harvested directly from the vibrating source mass rather than a vibrating seismic mass attached to the source increasing the harvesting bandwidth and power density. Four bar magnet and magnetic levitation architectures were modified and modeled to reach closer to the theoretical maximum power densities. Extensive FEM was utilized to understand the performance limitations of the existing structures and the results from this analysis paved the pathway towards the development of the DVH. �A comparative analysis of the performance of the DVH with the traditional harvesting methods in terms of normalized power output and bandwidth was conducted. Performance improvements of DVH required development of the high efficiency rotational generators as linear to rotational conversion occurs in the DVH. The optimized rotational generator was modeled and all the predicted performance metrics were validated through experiments. The generator was applied towards the fabrication of DVH and also in a micro windmill. The power density of the micro windmill was found to be better than all the other results reported in literature. Extensive fluid and structural modeling was conducted to tailor the performance of the micro windmill in the desired wind speed range. Combined, this thesis provides significant advancement on many fronts. It pushes the magnetic levitation and four-bar mechanism harvester systems to their theoretical limits. It demonstrates a novel direct vibration harvester that has the possibility of surpassing the power density and bandwidth of all the known vibration harvester with large magnitude of output power. It provides a design process for an efficient small scale electromagnetic generator that can form for the backbone of many rotational and linear harvesters. This generator was used to develop the world's highest power density micro windmill in the small wind speed range. / Ph. D.