Flush repairs to military aircraft are expected to become more prevalent as more thick skin composites are used, particularly on the surface of the fuselage, wings and other external surfaces. The use of these repairs, whilst difficult to manufacture provide an aerodynamic, ???stealthy??? finish that is also more structurally efficient than overlap repairs. This research was undertaken to improve the design methodology of scarf repairs with reduced material removal and to investigate the damage tolerance of scarf repair to low velocity impact damage. Scarf repairs involve shallow bevel angles to ensure the shear stress in the adhesive does not exceed allowable strength. This is important when repairing structures that need to withstand hot and humid conditions, when the adhesive properties degrade. Therefore, considerable amounts of parent material must be machined away prior to repair. The tips of the repair patch and the parent laminate are very sharp, thus a scarf repair is susceptible to accidental damage. The original contributions include: ??? Developed analytic means of predicting the stresses within optimised scarf joints with dissimilar materials. New equations were developed and solved using numerical algorithms. ??? Verified using finite element modelling that a scarfed insert with dissimilar modulus subjected to uniaxial loading attracted the same amount of load as an insert without a scarf. As such, the simple analytic formula used to predict load attraction/diversion through a plate with an insert may be used to predict the load attraction/diversion into a scarf repair that contains a dissimilar adherend patch. ??? Developed a more efficient flush joint with a doubler insert placed near the mid line of the parent structure material. This joint configuration has a lower load eccentricity than external doubler joint. ??? Investigated the damage tolerance of scarf joints, with and without the external doubler. The results showed that scarf joints without external doublers exhibited a considerable strength reduction following low velocity impact. Based on the observations, the major damage mechanics in the scarf joint region following impact have been identified. These results demonstrated that it is important to incorporate damage tolerance in the design of scarf repairs.

Insitu cementitious stabilisation is an economical, environmentally sustainable and socially advantageous means of rehabilitating pavements. With the recent availability of a wide range of binders and advanced construction equipment, the characterisation of cementitiously stabilised pavement materials has become the focus of further advancement of this technology. Australian practice has moved towards the use of Indirect Diametric Tensile (IDT) methods for the characterisation of these materials. A draft protocol for the IDT test has been prepared and specifies samples to be compacted by gyratory compactor. This procedure provides for both monotonic and repeated load testing, which aims to measure the material???s strength, modulus and fatigue life. A range of host materials, including a new crushed rock and a reclaimed existing pavement base course, were assessed when stabilised with a General Purpose cement binder as well as with a slag-lime blended binder. Materials were assess for their inherent material properties, Unconfined Compression Strength (UCS), Unconfined Compression modulus, IDT strength and modulus under both monotonic and repeated load. A number of amendments and refinements to the testing protocol were recommended. These included the use of minimum binder contents to ensure the binder was uniformly distributed and to promote heavy binding of the materials to ensure they behaved elastically. It was also recommended that samples be gyratory compacted to a pre-determined sample height to allow a constant density to be achieved. The variability of the test results was examined. UCS results were found to be comparatively as variable as other researchers had reported. IDT strength results contained a similar level of variability, which was considered to be acceptable. Modulus results, both monotonic and repeated load, were found to be five to ten times more variable than strength results, which is a generally accepted trend for modulus testing. Under repeated loading, some challenges with the test protocol were encountered. The primary challenge was obtaining reliable and repeatable diametrical displacement data for modulus calculation. This was partially overcome by the insertion of smooth spacers to prevent the Linear Voltage Displacement Transformer (LVDTs) becoming caught on the sample sides. The achievement of reliable and repeatable IDT modulus results through improved displacement measurements should be the focus of future research efforts in this area.

Amendments pasted onto front end-cover. / Bibliography: p. 221-240. / xvi, 354 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Documents the experimental and analytical research undertaken aimed at providing the fundamental tools required to succesfully avoid the identified brittle "weak link" in the design of new and the assessment of existing unreinforced masonary buildings. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 2000?

In the last two decades, the emphasis in aircraft maintenance has been on developing online structural health monitoring systems to replace conventional non destructive inspection techniques which require considerable down-time, human effort and cost. Vibration based damage detection is one of the most promising techniques for implementation in Structural Health Monitoring (SHM). In vibration based methods, the presence of damage is detected by monitoring changes in one of the dynamic parameters of the structure, resonant frequencies, modeshapes or damping characteristics. Compared to modeshape based methods, frequency based methods have the advantage that measurements need to be taken only at a single location. Previous developments on frequency based techniques have relied on Finite Element Model updating; analytical techniques have hitherto been restricted to beams due to the complexity in developing equations for cracked two dimensional structures. In this thesis the analytical approach using an energy formulation is extended to plates with through-thickness cracks, where modeshapes from either numerical modelling or experimental measurements can be employed to determine the energy of vibration. It is demonstrated that by using a hybrid approach, incorporating experimentally measured modeshapes along with measured changes in frequencies, the damage parameters can be estimated without resorting to theoretical modelling or numerical analysis. The inverse problem of finding the crack location, size and orientation from measured changes in frequencies is addressed using minimisation techniques. The forward problem and the inverse algorithm is first validated using numerical simulation and experimental testing of beams with edge cracks and centre cracks. The application of the methodology to the two dimensional case is then validated by numerical simulation and experimental modal analysis of plates with through thickness cracks. A statistical procedure is developed for determination of the 90/95 probability of crack detection and the minimum detectable crack size in both cases. It is demonstrated that the measurement of frequency changes can be successfully employed to detect and assess the location and size of cracks in beams and plates, using modeshapes from theory, Finite Element Analysis.

Thesis (D. Min.)--Liberty Baptist Theological Seminary, 2000. / Includes bibliographical references.

Membrane technology can be utilised for the high purification and desalination of water. However membrane filtration processes are commonly impeded by membrane fouling, which can lead to flux decline and an overall reduction in separation efficiency within the process. Therefore the aim of this research study was a comprehensive investigation of the issue of biofouling on industrial RO membranes through molecular biology techniques, characterisation of surface charge of foulant bacteria and RO membrane surface and AFM imaging and force measurements on clean and fouled membranes for the determination of adhesion force and micromechanical properties. The laboratories within Gwangju Institute of Science and Technology, South Korea and Swansea University, Wales were equipped for the scope of this research work. Research focused on the extraction of microbial DNA obtained from fouling layers on the surface of Reverse Osmosis Membranes obtained from the Fujairah Water and Power Plant, UAE. The use of the culture independent method of the molecular technique based on the 16S rDNA sequence and constructed gene libraries, was then used to determine the bacterial species that caused significant fouling on the RO membrane. Four bacterial species isolated from the fouling layer from the RO membrane were characterised in terms of electrophoretic mobility and zeta potential to determine the cell surface charge within various industrial relevant environments for the elucidation of cell adhesion mechanisms to the membrane surface. AFM images of virgin and fouled membranes were obtained and analysed to reveal the roughness of the surface which could influence fouling and the surface charge of the membranes were measured through the method of streaming potential at various industrial relevant environments to further elucidate the mechanisms of cell adhesion to the membrane surface. Force measurements were performed to reveal the adhesion force and elasticity values of virgin, process fouled and purposely fouled with the four bacterial isolates, to determine process behaviour in various environmental conditions. Through this research and future work, it is hoped that a rational strategy for economic and effective cleaning processes will be developed which will maintain efficient membrane operation and prolong membrane life, thus enabling the reduction of operating costs of such processes.

Orientador: José Pissolato Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T11:22:49Z (GMT). No. of bitstreams: 1 Carriel_LazaroPartamian_M.pdf: 4727086 bytes, checksum: dcf745210139d03b3d6ea5af9c6db4d8 (MD5) Previous issue date: 2012 / Resumo: O transformador é o maior ativo, o mais importante e o mais caro do sistema elétrico de potência. Este estudo tem a finalidade de apresentar uma metodologia e um processo de análise do ciclo de vida útil de transformadores de potência baseada na condição, para evitar perda de vida adicional devido ao acréscimo de carga em condição de contingência no sistema. A abordagem foi feita em duas fases e abrangem tanto a metodologia da norma ABNT como a norma do IEEE. Na primeira fase é verificado o comportamento do modelo térmico devido a sobrecargas e, na segunda, a influência das condições do óleo isolante / Abstract: The transformer is the largest, most expensive, most important asset in the electric power system. This study will present a methodology to analyze the useful life of power transformers based on their condition, in order to avoid incremental loss of life caused by overload under contingent operating conditions. The approach has been performed in two phases, following both ABNT and IEEE standards. In the first phase, a thermal model evaluates the effect of overloads on transformers' useful life. In the second phase, the influence of the conditions of the insulating oil is verified / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

M.Ing. (Mechanical Engineering) / Considering the high cost of maintenance, effective maintenance management have the potential to contribute to the profit of a petrochemical business. The complexity of the maintenance domain in the petrochemical business demands the use of information systems for the management of maintenance. The availability of correct, easily interpretable information about maintenance can therefore contribute to the profit of a petrochemical business. Management decisions are based on available information. The quality (accuracy and timeliness) of the information create more room for creative decisions in the maintenance department. A computerized information management system is a tool employed in the optimization of maintenance cost and a requirement for world class maintenance. This system depends on information of a high quality. It should be kept in mind that this systems is an aid to maintenance management and would never be able to replace the maintenance manager. The role played by high quality information in the success of a computerized maintenance management system point towards the importance of the personnel that maintain the system and those that provide input to the system. These personnel need to be highlytrained and should have the most recent technology available. Continuing development of the computerized maintenance management system within a company is necessary for the system to succeed.

Workers have the right to a safe working environment. This right is encapsulated in the Bill of Rights (1996) wherein strong emphasis is placed on the right to a healthy and safe work environment. The construction industry has been labeled as dangerous owing to regular incidents, serious accidents, and fatalities. Road workers’ safety is at high risk in road construction areas, as they perform their work activities alongside moving vehicles that are often large and sometimes moving at high speed. It was determined that very few secondary sources provided information regarding the safety of South African road construction workers. Therefore, the knowledge obtained from this study contributes to the body of knowledge on the subject matter. To collect data, three descriptive surveys were conducted on two different road construction projects within the Eastern Cape. The survey participants included engineering consultants, contractors, traffic safety officers, general road construction workers, as well as random motorists driving through the work zone. Further data was collected from a speed measuring instrument placed in the work zone of the Port Elizabeth. The findings of this research report indicate that road users are not cognizant of the risk to workers in the work zone and that signage and advance warning signs alone are not sufficient to slow motorists’ speed. A further significant threat to road worker safety, is plant operator visibility. This study recommends that government and construction firms educate the public regarding the risks associated with speeding through a work zone. Construction firms should use electronic speed measuring devices prior to the work zone to make road users aware of their speed in relation to the speed limit. To limit plant related accidents, companies should install sensors or cameras on the rear and side panels of plant, so that plant operators have all round vision. Furthermore, road workers could be educated on the controlled use of their mobile phones to reduce the risks associated with the use of mobile phones inside work zones.

The focus of the study was on the relationship between employee engagement strategies and intention-to-stay of engineering professionals at a power station. The investigated engagement strategies or drivers in the model adopted for this study included: leadership style, remuneration structure, physical and emotional work climate, nature of work and career development opportunities. The purpose of the study was to investigate and contribute to a better understanding of a voluntary turnover problem of engineering professionals at a power station by considering the influence of engagement on intention-to-stay. The research was conducted on a sample of 65 engineering professionals employed at a power station. The findings of the study revealed that only one variable, namely nature of work, was significantly related to employee engagement. It was also established that of the five engagement strategies investigated, nature of work and leadership style (transformational) were significantly related to intention-to-stay. A positive relationship between employee engagement and intention-to-stay was proven in this study.