Prediction of crushing stress in composite materials

A simple mathematical model for predicting the crushing stress of composite materials was derived and presented in this paper. The present knowledge of fracture mechanics and strength of materials are used as the basis for the model. The fracture mechanics part of the analysis was based on energy release rate approach; the energy release rate, G, of the proposed model was determined by this approach. This energy release rate was based on the Mode I (opening or tensile mode) failure. As for the strength of materials part analysis, buckling theory was used to determine the critical load of the fibre beams. These two engineering concepts were combined to form the equation for the proposed model. The derived equation is a function of the materials properties, geometric and physical parameters of the composite materials. The calculated stresses from the derived equation were compared with experimental data from technical and research papers. Good agreements shown in the results are encouraging and recommendations for future analysis with different modes of failure were also presented. This paper enables engineering designers to predict crushing stress in composite materials with confidence and makes their work more efficient and reliable

Dark Matter in Gauge Mediation from Emergent Supersymmetry

We investigated the viability of neutralino dark matter in the gauge mediation from emergent supersymmetry proposal. In this proposal, supersymmetry is broken at Planck scale and consequently, the gravitino is superheavy and completely decouples from the low energy theory. Squarks and sleptons obtain their soft masses dominantly through gauge mediation with other mechanisms highly suppressed. The lightest supersymmetric partner, in contrast to traditional gauge mediation, is a neutralino which is also a dark matter candidate. By explicit calculation of the low energy spectra, the parameter space was constrained using the WMAP observed relic density of dark matter, LEP2 Higgs mass bounds, collider bounds on supersymmetric partners and exotic B-meson decays. We found that the model has intriguing hybrid features such as a nearly gauge-mediated spectrum (the exception being the superheavy gravitino) but with a dominant mSUGRA-like bino-stau coannihilation channel and at large $\tan \beta$, A-resonance-like annihilation.Comment: 14 pages, 4 figure

Establishing links between organizational climate, employee well-being and historical patient outcomes

This research undertaken in collaboration with Queensland Health analysed the links between dimensions of workplace climate/employee well-being contained in a number of Queensland Health databases, including the Patient Satisfaction Survey, the Clinical Incident database, the compliments and complaints database, the Variable Life Adjusted Display (VLAD) Database and the Better Workplaces Staff Opinion Survey database. Queensland Health sought to identify in what ways workplace climate is related to patient outcomes using existing datasets collected within the Queensland Health Centre for Healthcare Improvement. The process of establishing links involved matching aggregated data for specific facilities (where possible), or failing that, larger facilities (e.g. Hospital), or the Health Service District. Once the datasets had been matched on location or facility, correlations were calculated between the aggregated scores. The results demonstrated links between the data sets. These links showed that a better workplace climate is associated with greater reported numbers of clinical incidents, especially “no harm” clinical incidents. There was also a link between workplace climate and patient compliments/complaints which show that unsolicited compliments received from patients and their families are clearly related to a number of positive aspects of workplace climate (workplace morale, role clarity, and appraisal and recognition) and individual morale. The results linking workplace climate and patient satisfaction showed that there is a strong positive relationship between overall patient satisfaction and role clarity, and a negative relationship between overall patient satisfaction and both workplace distress and excessive work demands. While these results relate to historical data and therefore should not be construed to reflect the current state of operation within Queensland Health, they are still indicative of some very important relationships. This is the first study to demonstrate that more positive clinical management practices, better perceptions of the workplace climate and better employee well-being are a reflection of a better incident reporting and learning culture in a health care organization, ultimately resulting in improved patient outcomes

Leadership in Action: The Effects of Leader-Member Exchange on Outcomes within Virtual Organizations

Player-founded organizations, or guilds, within massively multiplayer online games (MMOG) are complex social entities with organizational forms that mirror real-world companies. These guilds require leaders who possess a diverse array of skills. Examples of the skills required read like the introductory course of a business management degree – mediating conflict, planning, controlling, motivating. These skills are important - just as with real-world companies, failures on the part of leaders may explain the high degree of guild failures witnessed. The purpose of this purpose of this dissertation is to explore how relationships between leaders and members within this completely computer-mediated and synchronous environment affect member outcomes within guilds. I discuss how an exploratory study informs the choice of leader-member exchange theory to underpin this dissertation, develop a testable model which seeks to explain how relationship quality between leaders and members affects member outcomes as mediated by relational capital and the allocation of resources, and explain how this model will be operationalized and tested

Biomechanical evaluation of prosthetic feet

An evaluation method was developed which can be used generally for the assessment of any prosthetic feet. The two most common prosthetic feet prescribed to below-knee and above-knee amputees are the Uniaxial and SACH feet. A review of prescription practices shows that in the United Kingdom about 80% of the below-knee and above-knee amputees are fitted with a Uniaxial foot, whereas in the United States about 80% are fitted with the SACH foot. These contradictory prescription practices between the two countries, prompted the project to be concentrated on the evaluation of the SACH and Uniaxial feet. The method developed includes a subjective assessment procedure and a biomechanical evaluation on the function of the two prosthetic feet and their effects on whole body gait kinematics and lower limb kinetics. A review of the methods used in gait analysis is presented in the thesis. This forms a basis for the selection of a suitable gait recording system for the project. A background study of lower limb prosthetics in general and a review of prosthetic ankle/foot assemblies in particular are also presented. The methodology and instrumentation used in the project are given. Altogether, six below-knee and five above-knee amputees were tested. Due to insufficient supply of heel bumper stiffness by the manufacturer for the Uniaxial foot, heel bumpers of varying stiffnesses had to be made in the Bioengineering Unit. The development of the analytical procedure for the three-dimensional analysis is presented. A suite of computer programs was written to facilitate the handling of the large amount of data, details of which are included in the Appendix. Results from the analysis of the tests performed are discussed. Although some apparent differences were observed between the SACH and Uniaxial feet, no conclusion can be drawn as to which is better for the function of the amputee.An evaluation method was developed which can be used generally for the assessment of any prosthetic feet. The two most common prosthetic feet prescribed to below-knee and above-knee amputees are the Uniaxial and SACH feet. A review of prescription practices shows that in the United Kingdom about 80% of the below-knee and above-knee amputees are fitted with a Uniaxial foot, whereas in the United States about 80% are fitted with the SACH foot. These contradictory prescription practices between the two countries, prompted the project to be concentrated on the evaluation of the SACH and Uniaxial feet. The method developed includes a subjective assessment procedure and a biomechanical evaluation on the function of the two prosthetic feet and their effects on whole body gait kinematics and lower limb kinetics. A review of the methods used in gait analysis is presented in the thesis. This forms a basis for the selection of a suitable gait recording system for the project. A background study of lower limb prosthetics in general and a review of prosthetic ankle/foot assemblies in particular are also presented. The methodology and instrumentation used in the project are given. Altogether, six below-knee and five above-knee amputees were tested. Due to insufficient supply of heel bumper stiffness by the manufacturer for the Uniaxial foot, heel bumpers of varying stiffnesses had to be made in the Bioengineering Unit. The development of the analytical procedure for the three-dimensional analysis is presented. A suite of computer programs was written to facilitate the handling of the large amount of data, details of which are included in the Appendix. Results from the analysis of the tests performed are discussed. Although some apparent differences were observed between the SACH and Uniaxial feet, no conclusion can be drawn as to which is better for the function of the amputee