Stiffness identification of an impacted constraint is the main issue discussed in this thesis. Primarily, a change of stability (bifurcation) is used to determine the dynamical stiffness of an impacted beam for a piecewise-linear impact oscillator. Detailed one- and two-parameter bifurcation analyses of this impacting system are carried out by means of experiments and numerical methods. Particularly, the two-parameter numerical continuation of the obtained codimension-one bifurcation (period-doubling bifurcation, or fold bifurcation) indicates a strong monotonic correlation between the stiffness of the impacted beam and the frequency at which this bifurcation appears. In addition to the bifurcation techniques, another method for stiffness identification is analysis of impact duration. To accurately detect impact durations from numerical or experimental signals, nonlinear time series methods are utilised. Two impacting systems, including the piecewise-linear impact oscillator and a drillbit-rock vibro-impact system, are studied to demonstrate this proposed method. For either system, the impact duration is relatively constant when the response of oscillator is a period-one one-impact motion, and it is approximated as a half of the natural period of the oscillator-constraint system. When the mass of oscillator is constant, for an impacted constraint with a certain stiffness, the higher the stiffness, the lower the impact duration. This monotonic correlation provides another mechanism to estimate the stiffness of the impacted constraint. Based on the developed two dynamical methods for stiffness identification, a control algorithm for parameter adjustment of the axial vibration for rotary-percussive drilling applications is designed. This control algorithm aims to maintain the optimal drilling state under the varying formations. By this way, the efficiency of rotary-percussive drilling is expected to be promoted.

Since the introduction of helmets the incidence of traumatic brain injuries (TBI) in ice hockey has greatly decreased, but the incidence of concussions has essentially remained unchanged. Despite goaltenders in ice hockey being the only players on the ice for the entire game, few have assessed the performance of ice hockey goaltender masks. In ice hockey, goaltenders are exposed to impacts from collisions, falls and projectiles. The objective of this study was to assess the protective capacity of ice hockey goaltender masks for three accident events associated with concussion. A helmeted and unhelmeted medium NOCSAE headform were tested under conditions representing three common accident events in ice hockey. Falls were reconstructed using a monorail drop. A pneumatic linear impactor was used to reconstruct collisions and projectile impacts were reconstructed using a pneumatic puck launcher. Three impact locations and three velocities were selected for each accident event based on video analysis of real world concussive events. Peak resultant linear acceleration, peak resultant rotational acceleration and rotational velocity of the headform were measured. The University College Dublin Brain Trauma Model (UCDBTM) was used to calculate maximum principal strain (MPS) and von Mises stress in the cerebrum. The results demonstrated the importance of assessing the protective capacity of ice hockey goaltenders masks for each accident, as each event created a unique response. A comparison of unhelmeted and helmeted impacts revealed ice hockey goaltender masks are effective at reducing the risk of both concussion and TBI for falls and projectiles, but less so for collisions. Further, the risk of more serious injuries was found to increase for falls and collisions as impact velocity increased. The results highlight the importance of impacting multiple locations when assessing the protective capacity of ice hockey goaltenders masks, as different impact locations result in unique responses. Overall this study demonstrated ice hockey goaltenders masks capacity to reduce the risk of concussion across three accident events.

La présente thèse traite de l’impact d’un programme de microfinance et d’assistance technique (Programa Social Agropecuario ou PSA) mis en œuvre dans la province d’Entre Ríos, en Argentine. Cette thèse contribue à répondre à la question de l’impact de la microfinance sur le développement et des mécanismes pouvant maximiser cet impact en s’attardant principalement sur la perception des bénéficiaires. Pour ce faire, des entrevues et des groupes de discussions ont été menés dans 4 villages du département de Villaguay (Entre Ríos, Argentine) afin de dresser un portrait des interventions et des impacts de celles-ci sur leur vie. Les résultats ont été analysés depuis la perspective de l’approche des capabilités de Sen. Le PSA a permis à plusieurs individus de démarrer une activité productive mais les résultats sur le long terme sont mitigés. En effet, plusieurs ont abandonné depuis notamment en raison de vulnérabilités, nouvelles ou anciennes, qui n’ont pas été tenues en compte au moment du démarrage de l’activité productive. Par contre, la méthode de travail en groupe, les formations et les réunions ont permis des retombées intéressantes sur le plan du développement humain et particulièrement, pour les femmes.

Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.

It is widely accepted that design changes, occurring during construction projects, can account for a significant proportion of the engineering design consultant’s total cost. Projects with multidisciplinary, distributed and virtual project teams, working on technically challenging problems, make the impact of design changes increasingly difficult to predict. Existing guidance suggests ‘best practice’ protocols for recording, reporting and communicating design changes. However, best practice protocols do not provide guidance for predicting the impact in terms of project cost and duration. Impact assessments are essential in the decision to implement changes and subsequently being in a position to justify fee claims to clients. Decisions in the construction process are normally based on experience and professional knowledge of practitioners, such as architects, engineers, project managers and contractors. There is evidence, however, that, in design management, sharing of professional knowledge tends to be tacit and socially constructed (where team members draw on their own experience and the experience of those around them). Although practitioner experience and intuition is invaluable in determining the impact of a design change, this research is based on the position that a more structured process is required. It is argued that a software based approach, to better inform practitioners’ existing knowledge, is required to improve the quality and accuracy of impact assessments. The current practice for managing and assessing change was examined through studying the operations of the case study organisation, undertaking a literature review and conducting interviews with representatives from organisations in other industries. A new project management tool was then developed which provides support for practitioners to make better-informed impact assessments. This is achieved through providing: (a) a process map to visualise rework, (b) instant access to previous similar impact assessments and (c) an embedded, standardised method for knowledge sharing. The concept for this tool was developed by combining appropriate techniques and tools found in the design management and knowledge management literature. Users are further encouraged to use the software tool through a system to automate the updating of Microsoft Project schedules, thus eliminating time currently spent scheduling rework. The validation and verification stages consisted of formal interviews with potential users and preliminary user testing. Regular feedback on the support tool was obtained from a wide range of peers and potential users and this was then used to develop its functionality. Positive feedback has included comments about the concept of the tool, user-friendliness and need for implementation.

Dental decay remains a global issue but, in the UK, has become concentrated within the most vulnerable section of society, namely young children and the most deprived. When dental decay and subsequent infection become too severe, teeth may need to be extracted under General Anaesthetic. The aim of this work was to develop a greater understanding of the population of young children referred for a Dental General Anaesthetic (DGA) in the North West of England and to explore possible interventions that may positively impact on this group reducing the high number of children undergoing this procedure. A mixed methods approach was utilised, combining a broad scoping review, quantitative data collection and qualitative interviews. Individually these methods were used to develop a greater understanding of the issue and of the services, processes and patients involved in DGA. The methods were subsequently combined using triangulation to address potential preventative interventions that would be appropriate and acceptable to this group. Differences were observed between hospitals in treatment experiences of children across the North West of England. These included variations in the environment, hospital setting and time from referral to treatment, all of which were shown to impact on the child. The number of children experiencing a repeat DGA was also high and noted as an area that required further intervention. While DGA could be a distressing experience it was considered necessary and resulted in a positive outcome both in terms of oral health and a child’s quality of life. Improving oral health in young children who experience severe decay is a complex and challenging area. A number of interventions were identified that could reduce the need for extraction under DGA. These ranged from targeted interventions, linked to information provision and enablement to support those who are more at risk, to policy change with regard to excessive sugar in food and beverages that could have a broader impact across the population. In addition, DGA service re-designs are discussed including increased provision of prevention that may benefit children referred along this pathway and thereby reduce repeat DGA rates in the future.

Fibre reinforced composites have higher specific strength and stiffness in comparison to metals. However, composites are susceptible to impact damage resulting in degradation of mechanical properties especially compression strength. Numerous studies have been conducted to improve the impact damage tolerance of composite laminates using modified resin systems, thermoplastic matrices, 3-D fibre architectures and through thickness reinforcement. This work is primarily focussed on incorporating non dissolvable polypropylene fibres (PP) in a thermoset matrix for improving the damage tolerance. Commingling and wrapping techniques have been investigated. PP fibres have been incorporated at the preform stage and hence do not adversely affect the viscosity of the resin during infusion. The healing effect of PP fibres on impact damaged composite laminates when heating is introduced has also been studied. High velocity impact test results showed that using commingled glass/PP fibres increased the total energy absorption of composite laminates by 20% due to the extensive plastic deformation of the PP fibres and through the use of toughening mechanisms in the form of resin cracking and delamination. It has been found that PP fibres provide protection to the glass fibres during low velocity impact loading, so fewer fibre breakages occur which lead to improved residual properties compared with pristine glass laminates. Compression after impact (CAI) tests showed that the residual strength as a percentage of non-impacted strength increased with percentage of PP fibres used. For impact of 20-50J, glass/epoxy laminates retained 32 45% of their compressive strength while laminates with 7%, 13% and 18% PP fibres retained 37 50%, 42-52% and 43-60% of their compressive strength, respectively. It was also observed that glass/PP woven laminates had better compressive strength retention (62 83%) than the glass/PP non-crimp laminates (37-50%). Composite laminates with high-modulus PP fibres (Innegra) exhibited higher residual compression strengths in comparison to laminates with lower modulus PP fibres. For 15-50J impact, glass/Innegra laminates showed residual compression strength of 50 63% in comparison to 39-60%; laminates without thermoplastic fibres exhibited 33 43% residual compression strength. Modulus of thermoplastic fibres appears to be important at higher energy levels. Healing of damaged commingled laminates produced a significant reduction in the damage area and a corresponding increase in CAI strength after heating at 200ºC; CAI strength of healed laminates is about 85% of undamaged samples in comparison to 60% for non-healed samples. A novel micro-wrapping technique, developed in this work, demonstrated significant reduction in damage area (46%) in comparison to the commingling method. Core wrapped laminates had higher residual strength (43-60%) than glass laminates (33-43%). Better PP distribution in core-wrapped composites helped to decrease the PP rich areas and the impact damage did not propagate easily in comparison to commingled composites. However due to the reduction in damage area, impact energy absorption in core wrapped laminates was lower than for commingled.

The aim of this study was to investigate how Microfinance Institutions (MFIs) in South Africa balance sustainability with developmental objectives. Twelve semistructured, in-depth interviews were conducted with microfinance subject matter and microfinance institutions. The research found that commercialisation is not compatible with social impact as it leads to mission drift, which can be managed by an inclusive stakeholder governance structure. The trade-off between sustainability and social impact (outreach) was evident for commercial MFIs; while sustainability can be achieved through scale and cost management. In addition, MFIs achieve lower delinquency rate by implementing non-financial interventions such as client training and using group lending methodology that fosters social capital in the client base. The lack of a visible collaboration between MFIs has deprived the industry of a strong voice that can mobilise society to leverage the benefits of microfinance to help South Africa reduce inequalities. Despite the fact that regulatory restrictions concerning savings mobilisation for micro enterprise lenders are inhibiting product innovation and curtailing outreach, microfinance has proved to be a valuable tool that South Africa has not leveraged to alleviate poverty and reduce income inequalities. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted

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Thesis (M. A. (African languages)) --University of Limpopo, 2014 / In this research an attempt has been made to assess and investigate the impact of the in-laws on Tshivenḓa marriage. This study was found to be necessary because although other scholars have investigated various aspects with regard to the impact of the in-laws on Tshivenḓa marriage, an in depth research on their impact has not been conducted. According to the Tshivenḓa culture, when boys and girls become older they are expected to get married. So this marriage can be influenced negatively or positively by the in-laws. Some couples are forced to live with the in-laws. There are some marriages that do not last due to the negative interference of the in-laws but there are some marriages that are succeeding due to the positive relationship with the in-laws, therefore the aim of this research is to investigate the impact of in-laws on marriages.