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In the design of piping systems the importance of the pipe bend is well established. Recent publications have been increasingly concerned with the effect of end constraints on the behaviour of smooth pipe bends. This has been aimed almost exclusively at in-plane bending, there being no serious attempts at the solution to out-of-plane bending. In PART (1) of this thesis a theoretical solution is presented for the out-of-plane bending of linear elastic curved pipes with rigid flanges. The analysis employs the theorem of minimum total potential energy with suitable kinematically admissable displacements in the form of fourier series. Integration and minimisation is performed numerically. Results are given for a wide range of practical bend geometries. A comparison with previous theoretical predictions highlights the inadequacy of these earlier solutions. The present results are shown to be in favourable agreement with results from tests conducted by the author and more recent results using a different solution procedure. Work in the creep of pipe bends necessitates a substantial amount of experimental work and expertise. Most publications dealing with the creep of pipe bends under bending loads fail to present much information on this aspect. In PART (2) of this thesis a general description is given of an experimental creep programme on pipe bends. The measurement of strain at elevated temperature was accomplished using the CERL-PLANER capacitance strain gauge. It is shown that the application of this gauge to pipe bends requires particular techniques if meaningful results are to be obtained. The results of development work arising from other problems encountered during the test programme are also presented. These include the measurement of displacement and distortion at elevated temperature and the provision of an efficient and novel heating system.

Since the ancient years, human beings were using holes and caves to protect themselves from weather conditions making it the first known form of exploiting ground’s heat, known as Geothermal Energy. Nowadays, geothermal energy is mainly used for electricity production, space heating and cooling, Ground Coupled Heat Pump (GCHP) applications, and many other purposes depending on the morphology of the ground and its temperature. This study presents results of investigations into the evaluation of the thermal properties of the ground in Cyprus. The main objectives were i) to determine the thermal characteristics of the ground in Cyprus, ii) investigate how they affect the sizing and positioning of Ground Heat Exchangers (GHE) and iii) present the results for various ground depths, including a temperature map of the island, as a guide for engineers and specifiers of GCHPs. It was concluded that there is a potential for the efficient exploitation of the thermal properties of the ground in Cyprus for geothermal applications leading to significant savings in power and money as well. Six new boreholes were drilled and two existing ones were used for the investigation and determination of i) the temperature of the ground at various depths, ii) its thermal conductivity, iii) its specific heat and iv) its density. The thermal conductivity was determined by carrying out experiments using the line source method and was found to vary in the range between 1.35 and 2.1 W/mK. It was also observed that the thermal conductivity is strongly affected by the degree of saturation of the ground. The temperature of the undisturbed ground in the 8 borehole locations was recorded monthly for a period of 1 year. The investigations showed that the surface zone reaches a depth of 0.25 m and the shallow zone 7 to 8 m. The undisturbed ground temperature in the deep zone was measured to be in the range of 18.3 °C to 23.6 °C and is strongly dependent on the soil type. Since the ground temperature is a vital parameter in ground thermal applications, the temperature of the ground in locations that no information is available was predicted using Artificial Neural Networks and the temperature map of the island at depths of 20 m, 50 m and 100 m was generated. Data obtained at the location of each borehole were used for the training of the network. Data for the sizing of GHEs based on the ground properties of Cyprus were presented in an easily accessible form so that they can be used as a guide for preliminary system sizing calculations. With the aid of Computational Fluid Dynamics (CFD) software the capacity of the GHEs in each location and the optimum distance between them was estimated. Additionally, the long term temperature variation of the ground was investigated. For the first time since a limited study in the 1970’s, a research focusing on the determination and presentation of the thermal properties of the ground in Cyprus has been carried out. Additionally, the use of Artificial Neural Networks (ANNs) is an innovative approach for the prediction of data at locations where no information is available. The publication of this information not only contributes to knowledge locally but also internationally as it enables comparison with other countries with similar climatic conditions to be carried out.

Burkholderia pseudomallei et Burkholderia mallei sont respectivement les agents biologiques responsables de la mélioïdose et de la morve. Pour déterminer si les échecs thérapeutiques étaient dus à l'émergence d'une résistance acquise durant le traitement antibiotique, nous avons sélectionné des souches de Burkholderia thailandensis, modèle d'étude, B. pseudomallei et B. mallei, avec différents antibiotiques : le chloramphénicol, la doxycycline et le triméthoprime-sulfaméthoxazole. Les Burkholderia ont montré qu'elles étaient capables de développer une multirésistance in vitro en réponse à chaque antibiotique utilisé dans le traitement oral de la mélioïdose ou de la morve. Pour comprendre les mécanismes de résistance impliqués, nous avons étudié les aspects moléculaires et génétiques de la résistance chez B. thailandensis par des méthodes protéomiques et transcriptomiques. Nous avons développé une méthode pour quantifier l'expression des gènes de pompes d'efflux par RT-PCR quantitative après normalisation sur plusieurs gènes de référence. Ces méthodes nous ont permis d'identifier la surproduction séquentielle de trois pompes d'efflux de type RND : BpeAB-OprB, AmrAB-OprA et BpeEF-OprC, toutes induites par le chloramphénicol ou la doxycycline chez les souches multirésistantes. L'étude de mutants déficients en pompe d'efflux nous a permis de mieux appréhender les relations étroites entre ces trois pompes et a confirmé que l'efflux actif était le principal mécanisme impliqué cette résistance induite. / Burkholderia pseudomallei and Burkholderia mallei are respectively the causative agents of melioidosis and glanders. To determine whether treatment failures were due to the emergence of acquired resistance during antibiotic treatment, we selected strains of B. pseudomallei, B. mallei, and Burkholderia thailandensis, used as a study model of these two pathogenic bacteria, with structurally unrelated antibiotics: chloramphenicol, doxycycline and trimethoprim-sulfamethoxazole. We showed that Burkholderia were able to develop multidrug resistance in vitro in response to each of theses antibiotics used in the oral treatment of melioidosis and glanders. To understand the resistance mechanisms involved, we studied the molecular and genetic aspects of resistance in B. thailandensis by proteomic and transcriptomic methods. We have developed a method to quantify efflux pumps gene expression by quantitative RT-PCR after normalization with several reference genes. These methods allowed us to identify sequential overproduction of three RND efflux pumps: BpeAB-OprB, AmrAB-OprA and BpeEF-OprC, all induced by chloramphenicol or doxycycline in multiresistant strains. The study of mutants respectively defective in one of these efflux pumps has allowed us to better understand the close relationship between these three pumps and confirmed that active efflux acted as a major mechanism involved in the induced resistance.