No description available.

No description available.

No description available.

No description available.

Specific bacterial commensals demonstrating multidrug resistance (MDR) are opportunistic pathogens for immunocompromised patients, including Corynebacterium species (spp.). Severe infections due to MDR corynebacteria are being increasingly reported where several MDR phenotypes have been described. One such phenotype, the macrolide-lincosamide-streptogramin B phenotype (MLSB), is characterized by high-level resistance to macrolides, lincosamides, and streptogramin B. Resistance is thought to be attributable to acquisition of the ermX gene, a methyltransferase that alters the ribosomal macrolide binding site. Until recently, ermX had been reported in only six Corynebacterium spp. We have observed other corynebacteria can also display high-level resistance to MLSB antimicrobials and are ermX positive. Hypotheses being tested include: 1) high-level macrolide and lincosamide resistance in Corynebacterium spp. is caused by acquiring ermX; 2) distribution of ermX is more widespread than previously published; 3) ermX is associated with transposon Tn5432; 4) multidrug resistance has spread to Canadian C. afermentans and C. aurimucosum strains.

The main aim has been to investigate the effect of process parameters on the spray forming of UDIMET 720 and in particular to understand the mechanism of grain size evolution in the deposit using a combination of experimental and computer modelling techniques. Samples of two spray formed Ni superalloys, MAR-M-002 and UDIMET 720, have been re-heated into the solid/liquid region and the fully solid region just below the solidus temperature for a series of times to try and reproduce the situation of grain growth in a spray formed deposit. Grain growth in the solid/liquid region follows the equation: d³=d₀³ +Kt, where d is the grain size, d₀ is the initial grain size, K is the coarsening rate constant and t is the time. Coarsening rate constants have been determined for temperatures in the solid/liquid region and they increase with increasing temperature/decreasing solid fraction. Existing spray forming equipment for Al alloys has been modified to manufacture UDIMET 720 deposits. Process conditions were monitored continually during spray forming, in particular the temperature of the deposit by embedded thermocouples and infra red thermal imaging of the deposit top surface. Above a deposit temperature of ≈1250°C the microstructure consists of equiaxed fine grains (20μm-35μm) and the porosity is low (<1%). Below this deposit temperature the microstructure consists of droplet "splats" and the porosity is higher (2-4%). The measure grain size increases with increasing deposit temperature and solidification time and agrees reasonably well with the predicted grain size using the above equation. A commercial finite difference based fluid dynamics software program, FLUENT, has been used to model the 2-dimensional dynamic and thermal behaviour of UDIMET 720 droplets during gas atomisation and spray forming. The effect of atomising gas pressure, spray distance and melt mass flow rate on the equilibrated droplet spray temperature has been examined and shows similar variations with process parameters as the measured maximum deposit temperature. The predicted spray temperature at the substrate is always higher than the measured maximum deposit temperatures under all conditions, and increases with (i) decreasing gas pressure, (ii) decreasing spray distance and (iii) increasing MFR. Mean droplet temperatures and velocities are strongly dependent on droplet size, the mean droplet temperature decreases and mean droplet axial velocities increases with decreasing droplet size.

No description available.

Safety of a building's occupants is of primary concern in the design of a building. However, geophysical hazards such as earthquakes, still pose dangers to occupants of buildings. In an earthquake-resistant structure, even during a moderate shake, objects which are part of non-structural systems, accelerated by the sudden motion of the building, can hurt building occupants and cause damage to their property. The adoption of simple earthquake precautionary measures, could almost entirely eliminate this hazard. The adoption of these actions is the responsibility of occupants themselves, as part of their response to earthquake risk. / Previous personal experience with earthquakes has been identified to be a major component of response to hazard risk. This response relates to the incorporation of earthquake risk into daily life, by the adoption of earthquake precautionary measures, which could make a substantial difference in reducing loss of life and damage to property during an earthquake. Therefore, the investigation of occupants living patterns in relation to earthquake safety gives an insight on their vulnerability and level of adoption of earthquake precautionary measures, particularly in a city constantly exposed to ground shakes such as Mexico City. This research project concentrates in the study of the internal layout characteristics of the dwellings in a social housing complex built after the 1985 Mexico City earthquake.

Rotating machine play an important role in modern technology. Compressors in ventilating and cooling systems, pumps in power generation facilities, as well as high speed computer are all examples of flexible rotating machinery that must remain functional during and after a sever earthquake. Recent earthquakes have demonstrated that an aseismically designed structure may perform well during a strong earthquake yet still become nonfunctional due to damage in critical nonstructural components. For example, evacuation of several hospitals during the recent Northridge earthquake in the LA area was not caused by structural failure bur resulted from mechanical failure of the systems described above. Rotating machines are key components of such system. Further study into the behavior of these systems and technique for their protection for their protection during severe ground motion is needed. The flexible rotating machine is significantly complex, even for highly simplified models, due to gyroscopic and other effects. This paper presents the coupled, linear partial differential equations of motion of a flexible rotating shaft subjected to ground motion. Classical and finite element methods are developed to solve these equations. The effects of various physical parameters on the response of the system; magnitude, duration, and frequency content of the ground motion; bearing stiffness and damping; flexibility of the deformation and rotatory inertia effects are investigated, Both vertical and horizontal ground motion, individually and in combination, will be considered. / Graduation date: 1995

In the last decade, Australian civil engineers have not paid enough attention to earthquake resistant design of structures. It was commonly believed that the earthquake risk was insignificant thus earthquake resistant design was not considered for most buildings. Earthquake resistant design of structures has become an important issue in Australia following the Newcastle earthquake in 1989. / Masonry is one of the most commonly used materials throughout Australia for the construction of low rise buildings. Even though the history of past earthquakes has shown that masonry buildings suffered the maximum damage and accounted for the maximum loss of life, they continue to be popular. It was evident from the Newcastle earthquake that most unreinforced masonry structures were seriously damaged. Therefore it is important to retrofit and strengthen existing masonry structures to resist the potential earthquake damages. / For the last twenty years, several seismic retrofitting techniques for masonry structures have been developed and practiced, but rarely validated with experiments and numerical modelling. Further more, the research has been carried out mainly in America and Japan where the risk of major earthquake is high. In Australia, although unreinforced masonry is one of the most popular types of construction, research into seismic retrofitting of masonry structures is rare. / The purpose of this research is to develop a new, cheaper and high strength seismic retrofitting technique for masonry structures. An innovative retrofitting technique is presented for improving the seismic resistance of unreinforced masonry walls using cable systems. In this thesis, the experimental results from four unreinforced masonry walls and eight unreinforced masonry walls retrofitted with cable systems are presented. Seven unreinforced masonry walls retrofitted with FRP were also conducted in this research for comparison purpose. All walls were tested under combined constant gravity load and incrementally increasing in-plane lateral displacement reversals. The results showed that both the strength and ductility of tested specimens were significantly enhanced with this new technique. Seismic retrofitting of unreinforced masonry walls with cables proved to be an effective and reliable strengthening alternative. / In this thesis, a basic mechanical model has been introduced first using the simple truss model. Then, two nonlinear finite element models based on this basic mechanical model have been developed to validate the experimental results. One model is developed for unreinforced masonry walls retrofitted by cable system and the other model is developed for unreinforced masonry walls retrofitted by FRP. All of the models have been found between the analytical and experimental results are reasonably good agreement. The model takes into account the material nonlinearities as well as damage due to progressive cracking. Behaviour of the masonry is modelled using the theory of plasticity and cracking is modelled using smear cracking approach. The model is generated using ABAQUS Finite Element program. The validity of the model is established by comparison with the experimental results. It is shown that both of the numerical models are capable of predicting not only the load carrying capacity, but also the failure mode and, ductility of the retrofitted masonry walls. / This thesis reviews the literature on all seismic retrofitting techniques and compares their advantages and disadvantages to identify the most effective and economic retrofitting method for unreinforced masonry buildings. It also presents the basic concepts of seismic retrofitting and summarizes the findings from recent experimental and analytical research activities on the seismic retrofitting of unreinforced masonry buildings and provides some retrofit strategies on the most common failure modes. It is expected that this thesis will provide some guidelines to assist Australian engineers to retrofit unreinforced masonry buildings. / Thesis (PhD)--University of South Australia, 2005.