International Technology Transfer (the transfer of technology across national borders) is extensively believed to be necessary for the industrialisation of any country. The experiences of some successful countries in rapid economic and industrial development show that the acquisition of a significant amount of foreign technology has played a crucial role in promoting their managerial and technical expertise as well as increasing their productivity level In particular, the experiences of some successful East Asian Newly Industrialised Countries (NICs) during the past three decades indicate that they could achieve rapid industrialisation and technological development through the adoption of a set of appropriate policies and strategies. The experiences of these countries can have valuable lessons and policy implications for other countries which wish to follow the same path of rapid industrialisation and technological development. Although many Less Developed Countries (LDCs) have realised the great importance of technological transformation for their rapid economic and industrial development, they have not designed effective and efficient policies and strategies for the transfer of appropriate and high-level technologies. Therefore, it seems necessary for decision makers in these countries to formulate appropriate policies for effective and successful transfer of technology as well as rapid industrialisation. Iran, as a developing country with large natural and human resources has also attempted to adopt the best approach of technology transfer to improve and promote its technological capability and achieve rapid industrialisation. However, like many other countries, the industrial base of Iran can be characterised as being heavily dependent on importing their required parts and components for manufacturing outputs, which in tum is due to the assembly nature of many of its industries. In other words, Iran as wen as many other developing countries has been faced with heavy technological dependency. The main purpose of this study is to identify and examine the critical success factors for the effective technology transfer and rapid industrialisation of the LDCs in general and Iran in Particular. Firstly, some of the most important and relevant theoretical frameworks as well as conceptual issues of technology transfer and industrialisation of LDCs are analysed. The empirical and practical experiences of some selected countries in particular East Asian first and second tier Newly Industrialised Countries (NICs) as well as Mexico and Turkey are also studied. The critical success factors of these countries in rapid industrialisation and technological development are identified. Moreover, the past and present industrialisation policies as well as technology transfer status of Iran is investigated in detail to identify and determine the most important strengths and weaknesses which are needed for designing its future plan. Finally, a framework of an appropriate policy and strategy for international technology transfer to LDCs in general and Iran in particular is proposed. Some overall recollections and suggestions derived from the research findings and results for the effective and succesful technology transfer and industrialisation of LDCs in general and Iran in particular is also included.

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Orientadores: Gilberto D'Assunção Fernandes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-26T01:44:56Z (GMT). No. of bitstreams: 1 Guimaraes_Fernando_M.pdf: 10011651 bytes, checksum: a93242d30f0af2645d3e080c6b7aa6c5 (MD5) Previous issue date: 2000 / Resumo: Alguns trabalhos relataram a participação de estruturas límbicas na modulação da resposta imune. Com relação aos núcleos septais, a lesão ampla desta área alterou a resposta humoral de ratos imunizados com hemácias de carneiro, enquanto a lesão septal medial inibiu a resposta mitogênica in vitro de linfócitos T. Neste trabalho, investigou-se a influência da área septal do cérebro sobre as freqüências de linfócitos T CD4+ e T CD8+ no baço de ratos durante o desenvolvimento tumora!. Para isso, ratos com a área septal do cérebro lesada através de cirurgia estereotáxica (LW) e ratos controles (cirurgia simulada, SW) foram comparados após receberem uma inoculação subcutânea (sc) do tumor de Walker 256 Ar (variante celular com elevado índice de regressão, obtida a partir das células tumorais de Walker 256 A). A possibilidade da atividade adrenocortical mediar os efeitos septais foi verificada pela dosagem de corticosterona sérica. Também foi investigada a influência da lesão septal sobre os efeitos sistêmicos tais como, anorexia, ganho de peso corpóreo, retenção renal de sódio e água induzidos pelo tumor (modelo de inoculação multifocal com células tumorais de Walker 256 A ), visto a possibilidade de variações destes parâmetros fisiológicos servirem como uma indicação indireta da atividade imunológica. Com relação aos efeitos sistêmicos tumorais foi observado que a lesão septal causou uma redução temporária na retenção de sódio e água induzida pelo tumor, possivelmente como conseqüência da inibição da liberação do hormônio antidiurético. Duas semanas após a inoculação do tumor de Walker 256 Ar foram identificadas regressões tumorais em 46,2 % do grupo SW e 57,1 % do grupo LW. Tanto no grupo SW como no LWo percentual de linfócitos T CD4+ nos ratos cujos tumores não regrediram (SW = 19,5 ::t 1,4 %; L W = 23,8 ::t 1,6 %) foi significativamente menor que naqueles com regressão tumoral (SW = 29,3 ::t 2,4 %; LW = 31,4::t 1,6 %). Como conseqüência a relação CD4+/CDS+ também foi significativamente menor nos ratos cujos tumores não regrediram (SW = 0,91 ::t 0,07; LW = 1,20 ::t 0,07) que naqueles com regressão tumoral (SW = 1,45 ::t 0,1; L W = 1,59 ::t 0,1). Concluiu-se que as variações nas freqüências de linfócitos T, bem como na relação CD4+/CDS+ estiveram associadas ao desenvolvimento tumoral e não foram afetadas pela lesão ampla da área septal. Através de um experimento com ratos adrenalectomizados foi observado que o crescimento contínuo ou a regressão dos tumores, bem como a resposta imune celular associada a estes eventos, não foram influenciados pela atividade adrenocortical / Abstract: Some studies have shown the influence of limbie-hypothalamie areas on the immune response modulation. Concerning the septal nueleus, the whole lesion of this limbie area impaired the humoral immune response of rats immunized with sheep red blood eells, while lesions of the medial septal nueleus produced a long lasting inhibition of T Iymphoeyt proliferation induced by mitogens. The proposal of the present study was to investigate the influenee of septal area lesion on frequeneies of splenie T CD4+ and T CDS+ Iymphoeytes, during tumor development. Therefor, septal-Iesioned rats (LW), obtained through stereotaxie surgery, were compared with sham-operated rats (SW), afier one subeutaneous (se) inoculation of Walker 256 Ar tumor cells (a cell variant obtained from Walker 256 A tumor, distinguished by presenting a high regression ineidence). The adrenocortical aetivity in the mediation of septal lesion effects was evaluated by assessing serum corticosterone. The influenee of septal lesion on systemie effeets induced by the tumor, like body weight gain and, sodium and water renal retention was also investigated (by using the multifocal se inoeulation model of Walker 256 A cells). It was suggested that ehanges in these parameters would help as an indireet indication of the immunological function alterations. Conceming the systemie effects, sodium and fluid retention induced by the Walker 256 A tumor was temporarily reduced in animais with septal area lesions. This effect was possibly a result of an inhibition of antidiuretie hormone release. By using the Walker 256 Ar tumor cells, it was observed tumor regressions in 46.2 % of the SW group and 57.1 % of the LW group two weeks afier se inoculation. In both groups SW and LW, the frequency of splenic T CD4+ Iymphocytes was significantly reduced in rats which tumors did not regress (SW = 19.5:t 1.4 %; LW = 23.8:t 1.6 %) compared with rats with tumor regression (SW = 29.3:t 2.4 %; LW = 31.4 :t 1.6 %). As a consequence, the CD4+/CD8+ ratio was also significantly reduced in rats without tumor regression (SW = 0.91 :I:: 0.07; LW = 1.20 :t 0.07) in relation to those with tumor regression (SW = 1.45 :I:: 0.1; LW = 1,59 :t 0.1 %). Therefore, septal area lesion did not affect the frequencies of T Iymphocytes. Nevertheless, the alterations observed in the frequencies of T Iymphocytes, as well as in CD4+/CD8+ ratio were associated with tumor development (continuous growth or regression). It was also observed that tumor continuous growth or tumor regression, as well as the immune response associated with these events were not affected by adrenocortical activity / Mestrado / Fisiologia / Doutor em Ciências Biológicas

Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-04-18T17:31:50Z No. of bitstreams: 1 Salvador, Raquel Rocha Silva [Dissertação, 2012].pdf: 704535 bytes, checksum: 012b827ee322bb83f22e0531f9d7c888 (MD5) / Made available in DSpace on 2017-04-18T17:31:50Z (GMT). No. of bitstreams: 1 Salvador, Raquel Rocha Silva [Dissertação, 2012].pdf: 704535 bytes, checksum: 012b827ee322bb83f22e0531f9d7c888 (MD5) / Neste trabalho relatamos a síntese e avaliação de atividade tripanocida de novos derivados 4-carboidrazidas do sistema heterocíclico 1H-pirazolo[3,4-b]piridina, substituídos na posição C-6 por grupamentos metílicos (-CH3 ou -CF3). Foram obtidos 24 novos compostos, sendo 12 da série metílica e 12 da série trifluorometílica. Estes compostos foram identificados por métodos espectroscópicos e avaliados em ensaios biológicos in vitro a fim de verificar a atividade antiparasitária sobre a forma tripomastigota de T. cruzi. Os derivados da série metílica apresentaram melhor perfil de atividade tripanocida do que os derivados da série de trifluorometílica. O composto 1-fenil-3,6-dimetil-1H-pirazolo[3,4-b]piridina-4- carboidrazida (10) exibiu o mais significativo perfil antiparasitário (IC50= 227,9 μM) / This research report the synthesis and evaluation of trypanocidal activity of novel derivatives from 4-carbohydrazides of the heterocyclic system 1H-pyrazolo [3,4-b] pyridine, substituted in position C-6 by methyl groups (-CH3 or-CF3). It was obtained 24 novel compounds, with 12 from the methyl series and 12 from trifluoromethyl series. These compounds were identified by spectroscopic methods and evaluated by biological assay in vitro to verify the antiparasitic activity of the trypomastigotes from T. cruzi. The methyl derivatives showed better profile of trypanocidal activity than derivatives of the trifluoromethyl series. The compound 4- carbohydrazide-1-phenyl-3,6-dimethyl-1H-pyrazolo[3,4-b]pyridine (10) exhibited the most significant antiparasitic activity (IC50 = 227.9 μM)

The thesis presents analytical and experimental methods of studying various aspects of the optical and thermal performance of a transwall passive solar system. Some of these methods are applicable to other solar systems. Two ray-tracing techniques, 1-dimensional and 3-dimensional, are presented for an accurate calculation of the optical properties of a transwall module with its outside glass plate(s). These techniques calculate not only the reflected, absorbed or transmitted fractions of the incident radiation but also the spectrum of the transmitted radiation. This information is required for a better assessment of the transwall system as an illuminating source and as a thermal system. Both techniques are applied to a particular transwall module with one outside glass plate and the importance of various features of the incident solar radiation (such as spectrum, angular variation, polarization, etc.) are discussed. The difficulties associated with the nature of the diffuse solar radiation coming from the sky, or the ground , are overcome by employing a discretization method in which the continuous diffuse radiation is divided into discrete pencils of radiation. An analytical thermal model of a passive solar system is presented and its verification is established by using a test-box containing a full size transwall module. The outcome of this verification is satisfactory given the uncertainties of the optical and thermal properties of the various elements of the test-box. The success of the analytical modelling depends on accounting for the 3-dimensional solar radiation field outside and inside the passive solar system. The methods developed, accompanied by the two ray-tracing techniques, allow for an accurate distribution of the total incident radiation among the semitransparent elements and the external and internal surfaces of any passive system. The method of distributing the solar radiation among the internal surfaces of an enclosure is applied to the convex parallelepiped enclosure of the test-box and, as additional example of the method, also applied to the non-convex enclosure of a typical glasshouse with E-w transwalls. The phenomenon of the natural convection of a fluid inside a transwall module induced by the absorption of radiation is predicted by a numerical method, first introduced by Patankar. Examples of the temperature, pressure and velocity fields of three transwall modules filled with distilled water under the irradiance conditions of 400 to 500 W/m2 are presented. By introducing the effective conductivity concept the complicated phenomenon of the fluid convection inside the module is simplified to a conduction phenomenon. This is also necessary for the long term-days or months - analytical modelling of the total transwall passive system because the numerical prediction of the former phenomenon requires an excessive amount of computer time. The calculation of the effective conductivity is obtained by employing an analytical approach which makes use of the data collected from the application of the numerical method, mentioned above. Values of the ratio of the effective conductivity to the conductivity of the still water are calculated at two interfaces inside the water of four different transwall modules. Measurements of the temperature and the velocity at certain points in a small transwall module irradiated by a solar simulator have been performed to support some of the numerical predictions.

There are many harmful airborne microorganisms which can be breathed in by animals or humans and lead to illness or even death. Such organisms can land on surfaces or in liquid leading to other opportunistic routes to infection such as touch and ingestion. Consequently, there is a need to develop novel forms of decontamination and detection of pathogens in air, on surfaces and in liquids. The present work investigates these areas and in particular assesses the impact of novel laser and plasma decontamination systems on inactivation of Bacillus atropheaus spores, an anthrax simulant, in aerosols and on surfaces. To further evaluate the performance of the methods, it was necessary to identify how the spores flowed through the systems. Experiments were devised to quantify the effect of flow shaping and the electrode’s surface roughness, on the spore deposition. The spatial distribution of B. atropheaus spores on the electrodes was determined by using two methods, either a membrane filter or an imprinting (pressing) technique. Rougher surfaces allowed a higher level of microorganisms adhesion compared to smooth surfaces. The angle of incidence of the flowshaping on the spore distribution was investigated by using two angles, 10° and 30°. The capture was quantified by the number of spores that were counted on agar plates following incubation. The number of colony forming unit CFU was greatest near the entry point, and generally reduced along the electrodes’ length and was also greater for the 30° inlet angle. Computational Fluid Dynamics (CFD) techniques were applied to model the particular flow through the electrode geometry and for the laser decontamination system. Methods of spatial detection of microorganisms on surface were further developed using microscopy methods. Three methods were used in this research: optical microscopy examination to find the minimum detectable level of B. atrophaeus spores on surfaces, a fluorescence technique using LEDs was developed to investigate the spatial detection of spores and microalgae and a flow chamber system was developed that was used for cell counting of microalgae in liquid. The effect of excimer laser radiation on Escherichia coli vegetative cells and Bacillus atrophaeus spores was investigated. E. coli or B. atrophaeus spores were lawned onto agar plates and treated with pulsed excimer laser radiation at 248 nm. The plates were incubated overnight at 37 °C and assessed for areas of clearing or inactivation. The applied pulse energy was 37 mJ, the pulse repetition frequency (PRF) was either 20 or 100 Hz, exposures were from 1-10 pulses, or up to 1 min. The range of applied energy densities was from 0.31 to 18500 Jcm-2. Image processing techniques were developed to determine the cleared area, major and minor axis and fractional clearing away from the region directly exposed to the laser beam. The area of clearing was approximately linear for treatment against E. coli, and was non-linear against B. atrophaeus. Increasing the PRF increased the area of clearing, as did increasing the exposure time. Interestingly, these areas of clearing were much greater than the beam area (2 x 6 mm), suggesting that scattering of the radiation played a significant role in contributing towards inactivation away from the directly laser exposed region. The results showed that excimer lasers offer the potential for rapid decontamination of microorganisms and spores on surfaces. Simple protocols allow direct comparison of the inactivation efficacy of different laser sources and image processing techniques can be applied to accurately quantify these results. Growing and harvesting microalgae is important for sustainable and secure biofuel and food production. There is a wide spread interest in growing and exploiting the microalgae. The lipid, protein, carbohydrate and vitamin content of microalgae are not only species dependent but are also a function of their growth parameters such as nutrient, light, temperature and CO2. The importance of detection of microalgae on assessing optimal growth conditions was investigated, along with the impact of harvesting and lipid extraction. Image processing systems were developed to quantify the size distribution of microalgae as a determinant of growth efficiency.

Modern manufacturing processes require better quality control of the manufactured products at a faster rate, for achieving good throughput. This is increasing the need for process-oriented precision metrology capable of providing faster inspection and yielding valuable feedback to the manufacturing system for quality control of the manufactured products. Over the past twenty years optical sensors have emerged as a preferred method for the measurement applications in manufacturing automation, owing to some inherent advantages, such as high speed, high resolution, non-contact operation, and low cost. Improved online optical sensors for surface measurement would enable incorporating measuring systems into production processes and machines, improving the production performance and the quality of products, which is highly desired in many high/ultraprecision manufacturing applications. This thesis presents a novel spatially dispersed short coherence interferometry (SDSCI) sensor system for online surface measurement applications on the nanoscale. The SDSCI sensor system uses a low-cost broadband super-luminescent diode (SLD) with an emission bandwidth of 25 nm. Two measurement methods, phase shifting interferometry and Fourier transform for surface profile measurements, have been investigated in this study. The metrology sensor system incorporated the Michelson interferometer configuration with an optical probe in the measurement arm, while the reference arm had a mirror with a piezo-electric transducer. The technique involves surface scanning by spatially dispersing the broadband light using a reflective grating and a scan lens, and recording the resulting interferogram by using a high-speed spectrometer. The first measurement method involved investigations of implementation of phase shifting interferometry and the Carré algorithm for phase retrieval from the measured phase-shifted interferograms for profile measurements. Standard diamond turned multi-stepped and NPL artefact samples with 550-nm and 100-nm-high steps, respectively, were measured and confirmed the capability of the measurement sensor. The measurement speed of this technique was limited by the spectrometer speed and by the piezo-electric transducer movement. The optimised system has a measurement time of 1s. The second method was then investigated based on the Fourier transform profilometry technique for further increasing the measurement speed of the sensor device, as it required a single-shot interferogram, alleviating the need of any phase shifting. With increased measurement speed, this technique further reduced the problem of environmental noise inherent to all interferometer-based systems. Similar artefacts were measured by using this technique for evaluating its applicability for surface profile measurements. Once the sensor system was optimised and calibrated, the resulting open-space system could be further miniaturised into a compact sensor system by using optical fibres with a remote probe connected via a fibre link for use in embedded metrology applications. This method will be very beneficial in online inspection of samples in rollto-roll manufacturing processes, where the measurand is constantly moving. An example of such a measurement challenge is detection of defects on vapour barrier films formed by depositing an aluminium oxide layer several tens of nanometres thick on a flexible polymer substrate. Effective detection and characterisation of defects in this layer requires a single-shot approach with nanometre-scale vertical resolution.

This thesis concerns numerical investigations of the combustion behaviour of various combustion regimes. The simulations are based on modelling the flow of the fuels in the combustion devices. Computational fluid dynamics (CFD) modelling and analysis were used in three different works. FLUENT software, which is based on the finite volume method, is used to carry out all the simulations. Firstly, numerical simulations were carried out to investigate the turbulent non-premixed combustion of a mixture of methane (CH4) 90% and nitrogen (N2) 10%, on volume basis, inside an axis-symmetric cylindrical chamber (base case). The objective is to investigate the turbulent flow, flame propagation, temperature and species concentration and evaluate the effects of different reduced reaction mechanisms of methane and the influence of various turbulence models on them. The turbulent combustion inside the chamber occurs under a condition for which the equivalence ratio (ɸ) of 1.04 is used. Instead of using fully detailed chemical kinetics schemes and to reduce the computational costs, four global reduced chemical kinetics mechanisms are employed in the combustion model and they are named as (M-I, M-II, M-III and M-IV). The simulations, in which M-I is used, are performed by Renolds-Averaged Navier Stokes (RANS) approach with the three two-equation k-ϵ closures (standard, realizable and RNG) employed to model the turbulent flow. Concerning the chemistry-turbulence interaction, the finite-rate/eddy-dissipation model (FR/ED) is used. The first two of the above kinetics schemes are two-step reaction mechanisms and the other two are first-step and five-step reaction mechanisms, respectively. The latter one is used to assess the capability of FR/ED model for modeling such a mechanism. The influence of thermal radiation is also investigated by means of P-1 model. The standard k-ϵ model and realizable k-ϵ model are also modified and used in the course of simulations. Moreover, the reaction mechanism (M-II) is optimized to see its effects on the combustion process. The results are compared with the experimental data and gave good agreement. It is found that the best results are generally obtained using the modified standard k-ϵ model. Moreover, the simulation results using the realizable turbulence model are found to have large discrepancies compared to the experimental data. In comparison with the experimental data, the optimization of M-II (Em = 1.6x108 J/kmol) is found to have good results in terms of temperature. Increasing the dilution of the fuel by N2 is investigated. Four cases, CH4 (85, 80, 75 and 100%) on volume basis, are performed. The latter one concerns the combustion of pure methane. The results are compared with the base case and found that the base case is the best compromise to obtain the highest temperature in inside the chamber. Secondly, an axis-symmetric combustion model based on the Euler-Lagrange approach was formulated to model the combustion of pulverized bituminous coal. Three cases with three different char oxidation models are presented. In case1 and case 2, the diffusion and kinetic/diffusion global char models are used, respectively. Whereas, to model char oxidation in case 3, the multi-surface reactions model is used. The volatiles released during the devolatilization stage, which is modelled using a single kinetic rate model, are treated as one species and its combustion is modelled using the FR/ED model. The predicted results have good agreement with the available experimental data and the best predictions are obtained from case 3. The results showed that the combustion inside the reactor was affected by the particulate size. It is found that the burnout of the particle with the diameter of 16 μm at the exit of the furnace is 100%. Whereas, the burnout of the particles with diameters of 84, 154, 222, 291 μm is approximately 86, 75, 35, 33, 29 %, respectively. A number of simulations were carried out to find the best values of parameters suitable for predicting NOx pollutants. The chemical formation and reduction rates of NO are calculated by post-processing data obtained from the previously reacting flow simulations. This method is computationally efficient. For volatile-N is assumed that the nitrogen is released via the intermediates HCN and NH3. For char-N path way, it is assumed that all the nitrogen is released via the intermediate HCN. It is found that the assumption of the partition of volatile-N by 52% HCN, 10% NH3 and 38% NO has the best agreement with the experiment data. The influence of different operating parameters on the combustion process and NOx formation was investigated as well. For the same operating conditions and the same particles size distribution, the combustion of pulverised biomass alone, represented by straw, was investigated followed by the investigation of its firing with coal. The former one show a promising results under such operating conditions. It is found that the temperature distribution when burning straw particles is nearly the same as that obtained from burning coal because all the saw particles are completely burned out inside the furnace when compared with the coal particles. The NOx model, in which the ratio of HCN to NH3 is suggested to be for the partitioning of volatile-N, shows that NO formation is reduced by approximately 20% for case I and 26% for case II at the exit of the furnace when compared to coal. For the latter one the results of co-firing blends of coal with 10, 20, 30 and 40% share of biomass are presented and show the influence of co-firing on the combustion process. Co-firing of straw with coal enhances the combustion behaviour and increases the burnout of coal particles compared to that of coal firing only. It is seen that the burnout of the particles with sizes 84, 154 and 222 μm is remarkably increased. On the other hand, the burnout of the other two particles (291 μm and 360 μm) does not show a great change. The share of 10% of straw shows the highest temperature. Thirdly, Two-phase computational modelling based on the Euler–Euler was developed to investigate the heterogeneous combustion processes of carbon particles inside a newly designed combustion chamber. A transient simulation was carried out for a small amount of carbon powder situated in a cup which was located at the centre of the combustion chamber. A heat source was provided to initiate the combustion with the air supplied by three injection nozzles. The combustion simulations are performed for particle sizes with different diameters (0.5mm, 1mm, 1.5mm, 2mm, 2.5mm and 3mm). The particle of 1mm diameter is assigned to the baseline case. The results show that the combustion is sustained in the chamber, as evidenced by the flame temperature. It is shown that, up to a time of 0.55 s, the higher temperature was gained from the case of carbon particles with the diameter of 3 mm and burning the carbon particles with a diameter of 0.5 mm produces lower temperature. This may be attributed to the residence time of the carbon particles and the design of the burner. The larger particles stay longer than the smaller ones inside the chamber. This may due to the reason that the smaller particles follow the streamlines of the continuous phase and increasing the particle size leads to that the larger particles may deviate from the streamlines of the continuous phase and their slip velocity may increase resulting in enhancing convective transports of heat and species concentrations. The influence of the chamber design was also investigated. The height of the chamber is doubled. With the same operating conditions, up to a time of approximately 0.55 s, it is found that burning carbon particles in the doubled height chamber produces higher temperature than the baseline case (particle diameter 1 mm) and after this time the opposite takes place. Most of the other cases do so.

Visible light communication is a developing technology making use of light-emitting diodes (LEDs) and laser diodes in the visible spectrum for communication purposes. This thesis looks at the use of gallium nitride (GaN) devices for high speed measurements in free space, through fibre and underwater. Micro-pixellated LEDs (micro-LEDs) have been used as a source for these measurements and the different ways to drive these devices is explored. LEDs are limited in how fast they can be driven and therefore laser diodes are also considered for these high speed measurements. The frequency responses of such devices are measured and data transmission experiments are conducted. However, these devices can be used for more than just free-space communication. Laser diodes are much more powerful than their LED counterparts and can be modulated much faster making them ideal for fibre communications and underwater communications, where eye-safety is not an issue. By using these devices, a study of step-index plastic optical fibre (SI-POF) and multi-core fibre is carried out, analysing their dispersion properties and transmission characteristics. Further high speed measurements were conducted under the water as the need to communicate with unmanned vehicles under the ocean continues to be an important issue. Many security and defence companies and oil and gas industries are interested in this technology for that purpose, as the current setup is complex, expensive and limited in bandwidth. High modulation bandwidths and high data transmission rates are achieved, with some of the leading results in the field presented here. These results highlight the importance of the topic of visible light communication and show the attractiveness of using these visible GaN devices for this purpose.

Analytical, computational and experimental studies were carried out to investigate heat transfer and fluid flow in micro-channel absorber plates for compact (thin and light-weight) solar thermal collectors. The main objective of the work was to study different design and/or operating scenarios as well as study the significance of various micro-scaling effects. Analytical investigation showed that, under similar conditions, the proposed design yields a much higher fin efficiency, F and collector efficiency factor, F’ compared with the conventional solar collector design. An analytical model combining convective heat transfer in the collector fluid with axial conduction in the metal plate was developed. The predicted plate temperature profiles from the analytical model were in close agreement with the measured profiles. The model further showed that axial thermal conduction can significantly alter the plate temperature profile. Experiments were designed to represent real life operation of the proposed system. A CFD study, using the same design and operating parameters, produced results comparable with experiments. This numerical simulation also gave further insight into the heat transfer and fluid flow patterns in the micro-channel plate. The effect of channel cross section geometry was studied. The Nusselt number was observed to increase as the aspect ratio approached unity. Measured friction factors were similar in trend to the predictions for rectangular channels, although the overall rise in fluid temperature resulted in slightly lower friction factors. Thermal performance reduced slightly with increase in hydraulic diameter. The significance of various scaling effects was also investigated experimentally and numerically. Most of the typical scaling effects such as viscous dissipation and entrance effects were found to be insignificant however, conjugate heat transfer, surface boundary condition, surface finish and measurement uncertainties could be significant. The results showed a Reynolds number dependent Nusselt number which has been attributed to axial thermal conduction. It was also observed that only three walls were transferring heat; the walls of heat transfer had a uniform peripheral temperature while the heat flux varied peripherally. The closest simplified thermal boundary condition to represent heat transfer in these channels is the H1 with three (3) walls transferring heat. Increased surface roughness (obtained by using an etching technique to create the channels) was found to have a detrimental effect on heat transfer. The results showed that thermal improvement can be achieved by increasing the fluid velocity; however, pumping the thermal fluid above a pump power per plate area of 0.3 W/m2 resulted in marginal improvement. In practice, optimum microchannel geometry in plates should be sized based on fluid properties and operating conditions. The micro-channels should also have thin walls to minimise the effects of conjugate heat transfer. A Photovoltaic pump should be installed alongside the collector in order to provide pumping power required and minimise the overall fluid temperature rise. The results are beneficial for the design of micro-channel absorber plates for low heat flux operation up to 1000W/m2.