Thesis (M. Soc. Sc.)--University of Hong Kong, 1986.

Thesis (M.Soc.Sc.)--University of Hong Kong, 1986. / Also available in print.

A collection of hardware weightless Boolean elements has been developed. These form fundamental building blocks which have particular pertinence to the field of weightless neural networks. They have also been shown to have merit in their own right for the design of robust architectures. A major element of this is a collection of weightless Boolean sum and threshold techniques. These are fundamental building blocks which can be used in weightless architectures particularly within the field of weightless neural networks. Included in these is the implementation of L-max also known as N point thresholding. These elements have been applied to design a Boolean weightless hardware version of Austin’s ADAM neural network. ADAM is further enhanced by the addition of a new learning paradigm, that of non-Hebbian Learning. This new method concentrates on the association of ‘dis-similarity’, believing this is as important as areas of similarity. Image processing using hardware weightless neural networks is investigated through simulation of digital filters using a Type 1 Neuroram neuro-filter. Simulations have been performed using MATLAB to compare the results to a conventional median filter. Type 1 Neuroram has been tested on an extended collection of noise types. The importance of the threshold has been examined and the effect of cascading both types of filters was examined. This research has led to the development of several novel weightless hardware elements that can be applied to image processing. These patented elements include a weightless thermocoder and two weightless median filters. These novel robust high speed weightless filters have been compared with conventional median filters. The robustness of these architectures has been investigated when subjected to accelerated ground based generated neutron radiation simulating the atmospheric radiation spectrum experienced at commercial avionic altitudes. A trial investigating the resilience of weightless hardware Boolean elements in comparison to standard weighted arithmetic logic is detailed, examining the effects on the operation of the function when implemented on hardware experiencing high energy neutron bombardment induced single event effects. Further weightless Boolean elements are detailed which contribute to the development of a weightless implementation of the traditionally weighted self ordered map.

A combination of climate change, due to anthropogenic CO2 emissions and concerns over energy security, due to fluctuating fuel prices, has led to the UK pushing to increase its renewable energy production. Harnessing tidal stream energy is an infant sector in the UK’s renewable energy portfolio, despite the UK’s large tidal stream resource, and is harnessed through deploying tidal stream energy converters. This thesis focuses on the design of a novel vertical axis tidal turbine (VATT) called CarBine which is driven by drag force and therefore has several unique advantages, including slow rotational speed, omni-directionality and a simple design. This research focused on the optimisation of the CarBine design and was split into two areas: physical testing and numerical modelling. A conventional Savonius was also analysed in both of these respects and this enabled a direct comparison of CarBine to a competing drag force driven VATT. Physical testing measured the power of the turbines and was conducted in hydraulic flumes at both Cardiff University (CU) and IFREMER in Northern France for a range of flow conditions. Testing at IFREMER enabled the quantification of the blockage effect in the CU experiments. Physical testing resulted in the optimised design of CarBine being one with a four arm configuration. From physical testing at CU, CarBine showed inferior efficiency performance to that of the conventional Savonius, a Cp of 0.117 compared to 0.225 at U∞=0.72 m/s. As a result a hybrid of both the Savonius and CarBine was tested, namely a Savonius with flaps. However, results from physical testing showed the Savonius with flaps to have inferior performance to both CarBine and the conventional Savonius, with a Cp of 0.103 at U∞=0.72 m/s at CU. Numerical modelling was conducted using the commercial CFD software package, Ansys CFX. Both transient and steady state simulations along with 2D and 3D models were used to model both CarBine and the Savonius. Both the k-ε and SST turbulence models were used for comparison. The two degrees of rotational freedom present in the CarBine design resulted in CarBine being difficult to model precisely. The numerical modelling results were validated against the physical testing results and where available, 3D results showed closer validation than the 2D results.

This thesis addresses the architectural integration of transpired solar collectors (TSC), as a building envelope technology patented in 1980s to pre-heat ambient air that would be used for space heating. It explores the reasons for low take up of the technology. It further explores the preferences, perceptions and recommendations of architectural integration quality of TSC in buildings. The research analyses the associated technological innovation development at entrepreneurial level in the UK and North America in a variety of terms including knowledge diffusion and research and development. Building-integrated renewable energy is an important response to concerns about climate change and energy poverty. As space heating accounts for 61% of total domestic energy consumption in countries with long cold seasons, the transpired solar collector (TSC) is a promising technology. However, TSC suffers from low take up despite its apparent technical competitiveness. A large-scale questionnaire, an experimental prototype and technological innovation system analysis were used to provide insight into architecturally integrating and developing TSC technology in buildings, and clarifying its potential contribution to pre-heating ambient air. The research outcomes inferred multi-dimensional reasons behind limited adoption of the technology. Respondents were generally aware of TSC technology; however, few were satisfied with available technology. Various preferences determining selection of TSCs were investigated, including: ‘invisible’ integration, planning guidelines for traditional buildings, stage of integration and sustainable factors. Respondents indicated that the ultimate feature considered when sourcing TSC technology was its reliability followed by capital cost. The solar irradiation only needed to exceed 60W/m2 for TSC to generate an output temperature greater than the ambient temperature. A significant temperature increase was observed when solar irradiation exceeded 400W/m2. Output temperature increased to 16ºC above ambient temperature in autumn and 12ºC in winter in the TSC prototype. A comparison of relevant actors, institutions and networks of TSC in the United Kingdom (UK) with North America, found both to be cautious about communication to protect intellectual property: this hampers knowledge exchange and development. Despite TSC take up in North America being restricted by cheap gas prices, end-user feedback reflects a level of satisfaction versus fewer such examples in the UK. Identified barriers included immaturity of technology, reluctance to implement new technology, lack of supply chain and low institutional support. A framework of potential enablers and architectural design guidelines were proposed to breakthrough take up of TSC.

Many households in developing countries rely on biomass (wood, charcoal, agricultural wastes, sawdust, and animal dung) and coal to meet their energy needs. The burning of these fuels in open fires creates environmental problems one of which is indoor air pollution (IAP). For effective reduction of indoor air pollution in sub-Saharan Africa, it is therefore, important to understand factors that determine the choice and uptake of cleaner fuels for household energy use. This research investigates the salient factors influencing households in developing countries in choosing fuel types, using the households in peri-urban areas of Ado Ekiti, Ekiti State, Nigeria as a case study. This research used holistic approaches to understand energy issues in the study area and used methods such as questionnaires, interviews, and field observation during data collection. Key findings suggest that underlying socio-cultural contexts of households’ ethnic groups guided wood-fuel harvesting in the peri-urban areas of Ado Ekiti, Ekiti State, Nigeria. Wood fuel continues to be households’ main domestic energy source irrespective of their socio-economic status. The open burning of wood fuel causes indoor air pollution as the recorded 24-hour particulate matter levels was between 42µg/m3 – 275µg/m3 for indoor kitchens and 48µg/m3 – 648µg/m3 for outdoor kitchens. The cultural perception of the households that natural aeration blows particulates into buildings hinders them from believing that the open of burning of biomass fuels for domestic activities is the cause of indoor air pollution. Based on the findings of this study, it is argued that the traditional norms and values of the householders, being embedded in their socio-cultural contexts, are vital for understanding energy issues in the global South.

This research investigated novel decontamination methods of airborne microorganisms in enclosed public spaces. There are many ways the pathogenic micro-organisms can be transmitted from one body to another, which includes for example, physical contact between the contaminated surface to another, transfer of infected blood from a donor to another medium, or respiratory infections where the large droplets containing micro-organisms caused by talking, sneezing or coughing can infect another whether by direct or close contact, and airborne transmission where the tiny aerosol droplets containing the micro-organisms remain in the air for a long period of time thus spreading to wider areas, making this mode of transmission the most effective and thus dangerous. There are many technique and systems in the market today in the field of air cleaning, and many more under development, these include: ozone, plasma, UV, IR, microwave irradiation, passive solar exposure, pulsed light, electrostatic precipitation, photo-catalytic oxidation etc. However air decontamination using a laser is an unexplored approach. In general two different mechanisms are studied in detail in this research. The possibility of using radiation from the laser and also using plasma and its bi-products were investigated. Many variations and techniques were evaluated for both mechanisms to optimise each decontamination effect. Two types of lasers were used to investigate the concept of using lasers to decontaminate air: a CO2 laser producing a beam at 10.6 μm in the IR region and a KrF excimer laser producing a beam at 248 nm in the UV region. This research was to investigate and make use of the power that is available in the laser in a certain way to decontaminate the air. The effect of laser beam absorption in the presence of microorganisms was modelled in Matlab and this could be used to analyse any wavelength. Two variations of creating a plasma were investigated, one method used a Chang profiled, uniform field electrode and the other used an increased size flat electrode. The plasma produced from these systems emitted radiation around 200 nm to 900 nm. The Chang profiled electrode, which was manufactured in house, was originally designed to be used as a Nitrogen air laser. However, experiments with a purchased Nitrogen laser (detailed in Chapter 3) did not show any significant bacterial killing so the system was modified to be used as a plasma air decontamination device. The electrode was sized 60 mm x 10 mm, and the discharge volume was varied by altering the discharge gap. The effects of various parameters were investigated including: the discharge voltage, type of pre-ionisers to optimise the discharge and air flow shaping through the discharge region. Microbiological experiments conducted using air seeded with microorganisms was used to test the system’s decontamination efficiency. The second plasma system used larger 200 mm x 30 mm aluminium electrodes. Again various parameters were investigated to maximise the discharge stability which included, type of dielectric medium, type of power source, electrical circuit setup, use of laser marked electrodes, air flow shaping and using multiple electrode pairs running off the same power supply. Again, microbiological experiments conducted using air seeded with microorganisms was used to test the system’s decontamination efficiency. Two further systems were built using the results obtained from testing the 200 mm x 30 mm aluminium electrodes, an Industrial Based Air Decontamination Unit and a Ozone Shock Plasma System. Both systems were comprised with multiple pairs of laser marked electrodes with dielectric media and possible addition of flow shaping. The two systems were tested as before with good effect. The developed prototypes can be applied to most applications where air cleanliness is required.

This thesis explores urban smoke and its nuisances in Georgian England, especially focusing on the period, 1800-1830. During this period, a number of English towns experienced accelerated industrialisation and many of them first experienced air pollution. In 1821, Michael Angelo Taylor, MP, passed a parliamentary bill on smoke abatement, Taylor’s Act. Although it has generally been believed that the Act did not have much of a social impact, this thesis argues that the Act diffused the usage of smoke abatement technology and triggered dozens of legal cases. The geographical focus of this thesis is Leeds and London. The Leeds case study examines the Leeds smoke abatement campaign and the smoke nuisance court case against Benjamin Gott, a leading merchant/ manufacturer in Leeds. It shows that the confusion over the effectiveness of smoke abatement technology represented the main difficulty in the smoke abatement campaign. The court case between the Duke of Northumberland and Clowes represents an example of the London nuisance cases in the 1820s. After the introduction of the steam press, the printing business became a polluting business. Because the plaintiff was the aristocrat, the case was interpreted as a class issue between aristocrat and middle-class printer. However, it was the Duke’s servants who suffered most from the nuisance and the case shows more complex class politics. This thesis also explores smoke nuisance caused by conventional smoke-producing industries in London, waterworks and brickmaking. Some water companies adopted smoke abatement technology but the confusion over the effectiveness of the technology can be observed in London, too. Taylor’s Act did not directly influence brickmaking business but it could cause nuisance to its neighbours, especially nurseries and gardens.

The optimisation of biogas digesters is crucial for further development of sustainable energy sources. In this research, an integrative approach was taken to understanding how this problem can be addressed including: seeking a better understanding of protein – surface interactions on the molecular level; larger scale experiments to screen the best materials for use in laboratory scale anaerobic digesters to influence microbial growth and biofilm development as well as analysis of farm-scale data using the ADM1 multiparameter model. The laboratory-scale experiments were undertaken to develop surfaces suitable for studying microbial immobilization. This work, currently using tertiary amines, amine oxides and comparator oligoethylene glycol studies the adsorption of two classic model proteins: lysozyme and fibrinogen using quartz crystal microbalance methods and represents important steps for selecting and exploring surface – protein interactions. The data showed that tertiary amine oxides are more resistant to nonspecific protein adsorption than the corresponding tertiary amines. Heat modified polyurethane foam was used to explore biofilm and planktonic phase microbial populations in a fixed film biogas reactor. After four weeks the foam was analysed by ‘next generation’ 454-sequencing to identify the influence of the supporting materials on microbial population residing in anaerobic digesters. The results revealed that Spirochaetes, Methanobacterium and Methanocorpusculum associated themselves with heat modified polyurethane foams. Finally, data from a farm-scale anaerobic digester (volatile fatty acid concentration, temperature and pH) have been gathered and entered into the ADM1 model, developed by the mathematical modelling group from Lund University, to mimic the behaviour of a laboratory scale 1.5 l reactor and identify improved conditions for methanogens stability. The combination of approaches described above will allow the identification of which parameters will enhance the operation of anaerobic digesters and has identified surfaces that promote adhesion of particular Bacteria and Archaea in order to increase biogas production.

Local weather data (wind direction, wind speed and temperature) from meteorological stations and daily synoptic data have been examined in relation to airborne particulate material (PM10) concentrations recorded at 17 pollution monitoring sites throughout Kent for the period 2000 to 2008, as an aid to understanding dispersal patterns in relation to topography. In general, local and synoptic wind direction patterns followed the same trends: the yearly distribution is dominated by southwesterly winds, followed by winds from the west and the northwest. Detailed analysis of local wind patterns at four sites (two coastal and two inland) strongly suggested the presence of seas breezes, reaching maximum frequency between March and August and fewest occurrences between November and February. Transport of PM10 over 30 km inland was also inferred. In addition to local wind transport, the location of the pollution monitoring sites and their environment are key to explaining the differences in PM10 concentrations recorded between the sites. The 10 sites located on roadsides registered the highest number of particle counts, followed by the five sites located within urban areas. The lowest amount of particles was found at the two rural sites. The five roadside sites closest to London (two in Gravesham and three in Dartford) exceeded the daily recommended amount of 50 μg/m3 several times each month, probably reflecting the increased road traffic in those areas. Aside from the variation in PM10 amount between sites, seasonal differences were also observed, with the lowest amount of PM10 recorded in the autumn and the highest in spring. Episodes of pollution affecting the whole of Kent were also observed. These were more clearly related to the synoptic situation rather than any local wind variations and appear to indicate regional or trans-boundary pollution transport. The latter is also supported by preliminary evidence from a PM10 trap sampling at a site on the south coast.