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Endoscopy has become a very advantageous medical procedure particularly for investigative and operational surgery for cancer. The preferred method over open surgery, it offers the advantages of less invasion with shorter operation time, less trauma to the patient and quicker recovery time. The method proves beneficial to the patient as well as providing a cost saving to the NHS. This study made possible through a collaboration between The University of South Wales and the company partner, Cymtec Ltd. investigates the possibility of producing a solid-state LED or laser pumped phosphor white light system. The overall aim was to replace current xenon lamps, which have many unwanted characteristics with lower cost, higher efficiency and more environmentally friendly solid state devices to improve the benefits of endoscopic minimal invasive surgery even further. Instruments used in the procedures are small for use in restrictive spaces, the investigation therefore is focused on not just producing high power white light, but to provide high power white light that can be coupled into a small diameter liquid light guide (LLG), which can then be connected to endoscopic instruments. The etendue of the light therefore becomes a critical factor of the investigation. A patented light guide multiplexer technology designed by the company partner, Cymtec Ltd. which multiplexes light from red, green and blue high-power LEDs with relatively narrowband wavelengths is firstly reviewed. Following which development of the technology is achieved through careful consideration of optical bonding to increase efficiency whilst providing structural strength. From this investigation possible improvements to the system are identified and reviewed with a view to increasing the overall luminous output. As an alternative to multiplexing of blue, green and red LEDs to, phosphor technology is also investigated. YAG:Ce powdered phosphor coated on float glass in varying thicknesses is evaluated for suitability for pumping with high power LEDs and potentially lasers. The review highlights the importance of material properties and thermal dissipation in staying within the limits of the material. As a continuation, phosphor with ceramic or single crystal structures are identified and evaluated. High power blue lasers are used as the pumping source to overcome efficiency droop experienced by LEDs to increase output. Experimental analysis found the single crystal YAG:Ce option was deemed favourable due to the overall performance and light generated, proving suitable to be multiplexed with additional blue and red LEDs to produce white light. The combined light was then coupled into a Ø5mm liquid light guide, typically used for endoscopic equipment, providing over 1700 lm of D65 white light, a suitable alternative to xenon lamps for endoscopic procedures. To overcome the etendue limitation to using multiple LEDs as with lighting applications, a solution is designed to combine the output of multiple high power blue LEDs to pump phosphor whilst keeping the overall emitting area and etendue equivalent to that of the LED. The high reflective hollow light guide with internally coated phosphor design is firstly modelled in Zemax optical studio to prove the concept, using a suitable phosphor and binder combination. Bringing the concept to reality is achieved with custom components and specifically designed jigs. Testing the prototype proved the concept, with multi-LED phosphor converted light being generated and exiting the light guide with the same aperture size as the original LEDs. The output, found to be less than that modelled in the Zemax optical model is analysed with improvements to the design highlighted and discussed. Each method investigated proved to have advantages and disadvantages in comparison to each other. The study showed however the methods have merit in producing a soild-state based light engine to replace lamp based systems to provide optical performance whilst adding the advantage of colour tuning and overcoming the disadvantages and drawbacks of cost, lifetime and associated issues found with lamp based systems.

Flash-boiling of fuel sprays can occur when a liquid is discharged into an ambient environment with pressure lower than the fuels saturation pressure. The fuel enters a metastable superheated state which promotes atomisation and evaporation due to rapid phase change. The flash-boiling mechanism typically refers to high temperature thermally driven phase-change in the form of superheat, as opposed to mechanically driven low pressure phase-change associated with cavitation. Flash-boiling can exist in direct-injection spark-ignition engines operating at low in-cylinder pressures and/or high fuel temperatures. The addition of even small amounts of novel high volatile additives/fuels may also promote the onset of flash-boiling. Within multi-hole injectors flash-boiling can significantly vary spray formation, causing individual plumes to interact and collapse which can be both advantageous and detrimental to engine operation. The modelling of flash-boiling fuel sprays using a Lagrangian Particle Tracking framework within the CFD code of STAR-CD in the context of direct-injection spark-ignition engines was investigated in the current work. This included parametric studies into important aspects of flash-boiling as well as the development of flash-boiling sub-models which introduced thermal mechanisms such as in-nozzle phase-change, near-nozzle plume expansion through droplet shattering and increased evaporation rates. The parametric study highlighted the importance of increased atomisation and evaporation rates within flash-boiling sprays. This led to the development of two flash-boiling models which were applied to a wide range of operating conditions, single-component fuels and injector configurations. The models included a flash-boiling spray effective nozzle model and a flash-boiling breakup model which attempted to quantify both in-nozzle phase change effects and near-nozzle thermal atomisation, respectively. Both modelling techniques showed promise individually but also as a combination of in-nozzle and near-nozzle mechanisms. Important flash-boiling spray characteristics including complex plume interactions, spray collapse, droplet recirculation and effects on penetration lengths were captured and where possible quantitative and qualitative comparisons were made to experimental data. The developed flash-boiling capability was used to investigate spray and mixture formation within a direct-injection spark-ignition engine and the potential improvements in mixture homogeneity were confirmed.

This thesis is an extended examination of a lithograph, dated 1826, purporting to show a meeting of the Canterbury Catch Club—a musical society which flourished in the early nineteenth century. A very large collection of documents relating to the Club, now held in the Cathedral Library and Archives and the city Library, is used extensively to interrogate the print in order to assess what it tells us about the social, historical and cultural context within which the Club members and musicians promoted, performed and consumed the music which was, ostensibly, the Club’s raison-d’être. The thesis begins with an iconographical study comparing the image with other representations of convivial song of the period, and with contemporary written accounts of such evenings to be found in diaries and other literature, to ascertain how accurate it might be in its depiction of gentlemen at such an evening as this. After this, the archival evidence is then used to scrutinise, in Part I, that which is clearly visible; in Part II, that which is less clearly drawn—the musicians; and finally, in Part III, those elements conspicuous by their absence. Part I thus makes clear that the image is intended to assert the professional and socio-cultural identity of the gentlemen shown in the picture, by dint of careful composition and adherence to matters of dress, consumption, gender definition, and cultural association. Part II uses both Club and Cathedral records to investigate the extent to which the musicians employed by the Club may—as was often the case—have sung in the Cathedral Choir, and contributes to scholarship on this subaltern group of men by the use of detailed reference to hitherto unseen archival records. Part III—not for the first time in the thesis—notes the absence of women, whether as audience or performer, and then proceeds to a searching analysis of the musical repertoire itself, discussing the instrumental and vocal music which made up the programme of a Club evening, arguing that the musical taste evidenced here speaks volumes for the process of aspirational embourgoisement at work in this print and in society at large. This work is substantiated by extensive transcription, cataloguing and documentation of the Club’s archive and repertoire. Further reference is made to the clues herein about another aspect of Club culture noticeably absent from this print: the libertine revelry of the later evening singing. This speaks to a central point of the thesis: that this “after-evening” behaviour is a fascinating relic of the manners and mores of the Georgian period which gave it birth, offering Club members an opportunity to indulge in convivial behaviours which were unacceptable in more public environments. The thesis argues that the image is a telling assertion of socio-political identity at a turbulent point in British history, proclaiming an emerging certain social and economic status but also testifying eloquently to the continuation of an older, alternative, convivial culture.