Potable water production from atmospheric vapour using an ejector evacuated solar powered refrigeration system

This research project explores the possibility of using solar radiation energy to produce safe liquid water through the condensation of atmospheric water vapour for human consumption, livestock watering and also for small scale high value crop irrigation. The research activities are comprised of a literature study, comparison of similar devices in use, a design and prototyping exercise, a measure of development work to enhance the performance of the prototype and testing in Al-Batinah province in the Sultanate of Oman, where the author is currently on a work assignment. This dissertation describes the research activities performed to answer the following question: ‘Is it possible to economically produce sufficient quantities of liquid water from atmospheric vapour using only heat energy from the sun?’ This question poses a further two questions which need to be answered in the literature study. These are: ‘What is an economical price for clean drinking water?’ and ‘What is a sufficient quantity of water?’ The purpose of producing liquid water from atmospheric water vapour is an attempt to develop the technology to harvest an alternative and almost inexhaustible water source. The reason for requiring a new source of water is due to the fact that the available fresh water resources of the world are diminishing due to pollution, extensive utilisation and salination. Several references indicate that the problem is compounding itself due the increasing demand on a diminishing resource, with deepening negative effects on agriculture1, health2, economy3, industry and lifestyle4. Many future scenarios depict clean water as a scarce and expensive commodity, unaffordable to many. The condensation of atmospheric vapour is not a new concept. The literature study explores historical attempts to achieve this, as well as detailing the shortcomings of contemporary vapour condensation units as the modern state of the art. This survey covers the spectrum from large versions deployed by military and remote area construction operations to produce water for all purposes, to small desktop electrical water producing machines. The focus of the research is on a more environmentally conscious process, attempting to use a simple ejector driven device with sunshine as the energy source and water as the refrigerant. A further environmental enhancement of the concept is that of designing the machine to last for an extremely long working life, thereby diluting the carbon footprint of manufacture over a great number of years. A portion of the research is devoted to the development of a basic model which takes into account the climatic and meteorological variables to accurately predict a water harvest. The development of the model is then used to optimise the process, narrow the variability of assumptions and assist with the design. The model also serves to predict the performance of the unit in other locations under different prevailing climatic conditions. A design specification and a prototype are produced and tested. Finally the design is scrutinised using value engineering principles to reduce cost, effort and environmental impact and also to reduce the overall cost to provide a more economically viable appliance. The prototype device used in this study will use a collector area of 1 square meter, roughly equivalent to 1000 Watts of solar power under ideal conditions

The hydraulic transport of high concentration stabilized flow full plant mineral tailings

Summary in English.Photocopy of typescript.Includes bibliography.This thesis involves an analytical and experimental investigation of the flow behaviour of high concentration stabilized mineral tailings used as backfill material. At high solids concentrations "anomalous" behaviour occurs and is indicated by diameter dependancy on rheogram curves. These curves are not coincident in the laminar flow region. The anomalous behaviour is examined by postulating the following mechanisms : 1. Slip velocity at the pipe wall 2. Wall effects due to particle interaction 3 . Boundary layer effects 4. Plug flow at high concentrations 5. Particle migration away from the wall leaving a sheared annular zone 6. Lateral dispersive stress acting between particle and pipe wall. The mechanism responsible for "anomalous" behaviour is found to be due to the presence of a dispersive stress acting on the pipe wall due to particle-particle and pipe wall contact. This only occurs above a critical solids concentration ratio which is defined in terms of the critical void ratio or freely settled particle concentration. The total wall shear stress is a combination of both the viscous shear stress and the solid shear stress due to the lateral dispersive stress. Measured data was obtained from several test facilities. in pipe diameters ranging from 13,48 mm to 101,5 mm and for solids volumetric concentrations from 25% to 55%. Measurements included mean mixture velocity, pressure gradient, in situ and delivered volumetric concentration, temperature and the solids particle size distribution. Vertical down pipeline pressure gradients were obtained for a 40 mm NB pipeline which was constructed for the research. A tube viscometer was used to obtain rheological parameters. The measured data was compared with several analytical models using the log standard error. Existing models were found to be unsuitable for these slurries. The "anomalous" behaviour of the high concentration stabilized slurries is explained. The flow behaviour of these slurries is analysed in detail. The output is in the form of a user friendly interactive pipeline design computer program

A study of ship wave resistance from an analysis of the wave pattern using close range photogrammetry

Bibliography: pages 156-162.In this thesis the wave pattern generated by a moving ship is investigated experimentally using close range photogrammetry. The author has been primarily interested in validating a new approach in the determination of the wave making resistance of a ship by means of the energy contained within the wave pattern. Secondary considerations were the measurement of the total ship resistance and other dynamically related applications; squat and trim, bow and stern wave profiles and their interactive effects. The proposed theoretical approach in this analysis of the wave resistance from the wave pattern is essentially phenomenological. As a ship proceeds through the fluid, it generates a set of waves radiating from the bow and stern due to the pressure differences along the hull. Energy is needed to maintain this system and is supplied at a constant rate by the ship, this being the energy required to overcome wave-making resistance. If the total change in energy within the wave pattern can be evaluated over a time interval associated with a known ship movement, then the energy difference will be a related to the wave making resistance

Technology as text: the changing meanings of the fixed and mobile telephone

Recent sociological studies of the mobile phone and the fixed line telephone have drawn attention to the changing meanings of communications technologies. Whilst manufacturers often represent “preferred” uses in product marketing, users frequently subvert such intended purposes, modify them or invent new practices. Mobile phones, whose “essential” function was verbal communication, were initially designed and marketed for business and professional use. Today we use them to chat and keep in touch with our children. Their basic function of speech communication has been subverted as teenagers opt to for text messages. School-children have invented new social uses despite the efforts of mobile phone companies to persuade them otherwise.Traditionally, social scientists have assumed that a device such as the telephone has an intrinsic purpose determined by some essential property of its technology. Such an approach stands in contrast to the analysis of works of art or products of the media where factors such as religious belief, social values and political ideology are routinely invoked to explain their various interpretations. This paper suggests that such a dichotomy is false. Concepts from cultural studies and communications theory are used to argue that technologies such as the telephone are cultural products with symbolic as well as economic value and that users can shift their meanings

Enhancement of domestic solar photovoltaic unit productivity through the use of a cost effective tracking system

The majority of new and existing small photovoltaic (PV) installations in South Africa are fixed-panel systems, largely due to the cost of photovoltaic panel components having reduced steadily in recent years where an increased requirement is met with a larger number of panels, whilst tracking system costs remain prohibitively expensive. Fixed installations realise only a part of their energy potential as they are truly effective for only short periods of the day. The aim of this study is to investigate and build on the current technology of PV tracking systems with the aim of specifying a simple control and actuation system which performs the tracking function. The eventual purpose of this thesis is to reliably produce more energy from solar photovoltaic installations than similar installations using fixed panels. This would be achieved by the use of an effective and affordable tracking system which yields acceptable accuracy and reliability and opens the potential for the system to be further developed for other purposes. These alternative uses could be the control of sunlight into green buildings, control of dampers for building ventilation and cooling and Trombe wall air control. This study has investigated the potential of several passive and active methods to actuate a sun tracking system. A useful closed loop system, which uses low pressure hydraulics, was developed and tested. The prototype is detailed in the drawings, Appendix D.Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, 202

Enhancement of domestic solar photovoltaic unit productivity through the use of a cost effective tracking system

The majority of new and existing small photovoltaic (PV) installations in South Africa are fixed-panel systems, largely due to the cost of photovoltaic panel components having reduced steadily in recent years where an increased requirement is met with a larger number of panels, whilst tracking system costs remain prohibitively expensive. Fixed installations realise only a part of their energy potential as they are truly effective for only short periods of the day. The aim of this study is to investigate and build on the current technology of PV tracking systems with the aim of specifying a simple control and actuation system which performs the tracking function. The eventual purpose of this thesis is to reliably produce more energy from solar photovoltaic installations than similar installations using fixed panels. This would be achieved by the use of an effective and affordable tracking system which yields acceptable accuracy and reliability and opens the potential for the system to be further developed for other purposes. These alternative uses could be the control of sunlight into green buildings, control of dampers for building ventilation and cooling and Trombe wall air control. This study has investigated the potential of several passive and active methods to actuate a sun tracking system. A useful closed loop system, which uses low pressure hydraulics, was developed and tested. The prototype is detailed in the drawings, Appendix D.Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, 202

Preprosthetic Surgery-Narrative Review and Current Debate

This review describes the role of modern preprosthetic surgery. The atrophic edentulous jaw can cause severe functional impairment for patients, leading to inadequate denture retention, reduced quality of life, and significant health problems. The aim of preprosthetic surgery is to restore function and form due to tooth loss arising from congenital deformity, trauma, or ablative surgery. Alveolar bone loss is due to disuse atrophy following tooth loss. The advent of dental implants and their ability to preserve bone heralded the modern version of preprosthetic surgery. Their ability to mimic natural teeth has overcome the age-old problem of edentulism and consequent jaw atrophy. Controversies with preprosthetic surgery are discussed: soft tissue versus hard tissue augmentation in the aesthetic zone, bone regeneration versus prosthetic tissue replacement in the anterior maxilla, sinus floor augmentation versus short implants in the posterior maxilla-interpositional bone grafting versus onlay grafts for vertical bone augmentation. Best results for rehabilitation are achieved by the team approach of surgeons, maxillofacial prosthodontists/general dentists, and importantly, informing patients about the available preprosthetic surgical options.</p

LiDAR, UAV or compass-clinometer? Accuracy, coverage and the effects on structural models

This study was carried out as part of a University of Aberdeen provided PhD supported by The NERC Centre for Doctoral Training in Oil & Gas, (grant reference: NE/M00578X/1). Thanks to Magda Chmielewska for her training and help with LiDAR processing, without which this study could not have been undertaken. Midland Valley Exploration is thanked for academic use of Move 2016 software. We gratefully acknowledge the detailed and constructive reviews by Mike James and an anonymous reviewer, and thanks to Bill Dunne for careful and thorough editorial comments, all of which greatly improved the manuscript.Peer reviewedPublisher PD