Auxiliary absorbers provide an effective means to attenuate the vibrations of a structural or mechanical system (the "primary structure"). The simplest auxiliary absorber, a tuned mass damper (TMD), provides reliable narrow-band attenuation but is not robust to the effects of detuning. Strongly nonlinear tuned mass dampers (NTMDs) are capable of wide-band, irreversible energy transfer known as "energy pumping" but can also exhibit high amplitude solutions which significantly amplify the response of the primary structure. Semi-active tuned mass dampers (STMDs) incorporate an actuating element in order to achieve real-time tuning adjustment capability. This thesis presents a global dynamic analysis of the response of a primary structure with an NTMD and then explores the performance of a novel absorber configuration consisting of an NTMD and STMD attached to the primary structure in series. The global dynamic analysis is conducted using a new cell mapping method developed by the author and introduced within the thesis: the parallelized multi-degrees-of-freedom cell mapping (PMDCM) method. The benefits of the additional STMD component are explored for two distinct applications: (1) restoring the performance of a linear TMD which develops a weak nonlinearity due to operation outside of the intended range or other means, and (2) acting as a safety device to eliminate or minimize convergence to the detached high-amplitude response. In the weakly nonlinear case, the STMD is shown to reduce the effects of the nonlinearity and improve attenuation capability by constraining the motion of the NTMD. In the strongly nonlinear case, the STMD effectively eliminates the complex response behavior and high amplitude solutions which were present in the original system, resulting in a single low amplitude response. Experimental tests using an adjustable-length pendulum STMD verify the numerical results.

A stacked microchannel heat sink was developed to provide efficient cooling for microelectronics devices at a relatively low pressure drop while maintaining chip temperature uniformity. Microfabrication techniques were employed to fabricate the stacked microchannel structure, and experiments were conducted to study its thermal performance. A total thermal resistance of less than 0.1 K/W was demonstrated for both counter flow and parallel flow configurations. The effects of flow direction and interlayer flow rate ratio were investigated. It was found that for the low flow rate range the parallel flow arrangement results in a better overall thermal performance than the counter flow arrangement; whereas, for the large flow rate range, the total thermal resistances for both the counter flow and parallel flow configurations are indistinguishable. On the other hand, the counter flow arrangement provides better temperature uniformity for the entire flow rate range tested. The effects of localized heating on the overall thermal performance were examined by selectively applying electrical power to the heaters. Numerical simulations were conducted to study the conjugate heat transfer inside the stacked microchannels. Negative heat flux conditions were found near the outlets of the microchannels for the counter flow arrangement. This is particularly evident for small flow rates. The numerical results clearly explain why the total thermal resistance for counter flow arrangement is larger than that for the parallel flow at low flow rates. In addition, laminar flow inside the microchannels were characterized using Micro-PIV techniques. Microchannels of different width were fabricated in silicon, the smallest channel measuring 34 mm in width. Measurements were conducted at various channel depths. Measured velocity profiles at these depths were found to be in reasonable agreement with laminar flow theory. Micro-PIV measurement found that the maximum velocity is shifted significantly towards the top of the microchannels due to the sidewall slope, a common issue faced with DRIE etching. Numerical simulations were conducted to investigate the effects of the sidewall slope on the flow and heat transfer. The results show that the effects of large sidewall slope on heat transfer are significant; whereas, the effects on pressure drop are not as pronounced.

In this thesis, a novel anti-sensor network paradigm is introduced against wireless sensor networks (WSN). Anti-sensor network (ASN) aims to destroy application reliability by adaptively and anonymously introducing adequate level of artificial distortion into the communication of the event features transported from the sensor nodes (SN) to the sink. ASN is composed of anti-sensor nodes (aSN) randomly distributed over the sensor network field. aSNs pretend to be SNs tomaintain anonymity and so improve resiliency against attack detection and prevention mechanisms. Performance evaluations via mathematical analysis and simulation experiments show that ASN can effectively reduce the application reliability of WSN.

The work reported in this thesis is an attempt to enhance heat transfer in electronic devices with the use of impinging air jets on pin-finned heat sinks. The cooling per-formance of electronic devices has attracted increased attention owing to the demand of compact size, higher power densities and demands on system performance and re-liability. Although the technology of cooling has greatly advanced, the main cause of malfunction of the electronic devices remains overheating. The problem arises due to restriction of space and also due to high heat dissipation rates, which have increased from a fraction of a W/cm2to 100s of W /cm2. Although several researchers have at-tempted to address this at the design stage, unfortunately the speed of invention of cooling mechanism has not kept pace with the ever-increasing requirement of heat re- moval from electronic chips. As a result, efficient cooling of electronic chip remains a challenge in thermal engineering. Heat transfer can be enhanced by several ways like air cooling, liquid cooling, phase change cooling etc. However, in certain applications due to limitations on cost and weight, eg. air borne application, air cooling is imperative. The heat transfer can be increased by two ways. First, increasing the heat transfer coefficient (forced convec- tion), and second, increasing the surface area of heat transfer (finned heat sinks). From previous literature it was established that for a given volumetric air flow rate, jet im-pingement is the best option for enhancing heat transfer coefficient and for a given volume of heat sink material pin-finned heat sinks are the best option because of their high surface area to volume ratio. There are certain applications where very high jet velocities cannot be used because of limitations of noise and presence of delicate components. This process can further be improved by pulsating the jet. A steady jet often stabilizes the boundary layer on the surface to be cooled. Enhancement in the convective heat transfer can be achieved if the boundary layer is broken. Disruptions in the boundary layer can be caused by pulsating the impinging jet, i.e., making the jet unsteady. Besides, the pulsations lead to chaotic mixing, i.e., the fluid particles no more follow well defined streamlines but move unpredictably through the stagnation region. Thus the flow mimics turbulence at low Reynolds number. The pulsation should be done in such a way that the boundary layer can be disturbed periodically and yet adequate coolant is made available. So, that there is not much variation in temperature during one pulse cycle. From previous literature it was found that square waveform is most effective in enhancing heat transfer. In the present study the combined effect of pin-finned heat sink and impinging slot jet, both steady and unsteady, has been investigated for both laminar and turbulent flows. The effect of fin height and height of impingement has been studied. The jets have been pulsated in square waveform to study the effect of frequency and duty cycle. This thesis attempts to increase our understanding of the slot jet impingement on pin-finned heat sinks through numerical investigations. A systematic study is carried out using the finite-volume code FLUENT (Version 6.2) to solve the thermal and flow fields. The standard k-ε model for turbulence equations and two layer zonal model in wall function are used in the problem Pressure-velocity coupling is handled using the SIMPLE algorithm with a staggered grid. The parameters that affect the heat transfer coefficient are: height of the fins, total height of impingement, jet exit Reynolds number, frequency of the jet and duty cycle (percentage time the jet is flowing during one complete cycle of the pulse). From the studies carried out it was found that: a) beyond a certain height of the fin the rate of enhancement of heat transfer becomes very low with further increase in height, b) the heat transfer enhancement is much more sensitive to any changes at low Reynolds number than compared to high Reynolds number, c) for a given total height of impingement the use of fins and pulsated jet, increases the effective heat transfer coefficient by almost 200% for the same average Reynolds number, d) for all the cases it was observed that the optimum frequency of impingement is around 50 − 100 Hz and optimum duty cycle around 25-33.33%, e) in the case of turbulent jets the enhancement in heat transfer due to pulsations is very less compared to the enhancement in case of laminar jets.

This research investigates the character and significance of shelf-edge deltas within the sedimentary source-to-sink system, and how variability at the shelf edge leads to different styles of deep-water deposition. Because the shelf-edge represents one of the key entry points for terrigenous sediment to be delivered into the deep water, understanding of the sedimentary processes in operation at these locations, and the character of sediment transported through these deltas is critical to understanding of deep-water sedimentary systems. The research was carried out using three datasets: an outcrop dataset of 6000 m of measured sections from the Permian-Triassic Karoo Basin, South Africa, a 3D seismic data volume from the Eocene Northern Santos Basin, offshore Brazil and a dataset of 29 previously published descriptions of shelf-edge deltas from a variety of locations and data types. The data presented highlight the importance of sediment instability in the progradation of basin margins, and deep-water transport of sediment. The strata of the Karoo Basin shelf margin represent river-dominated delta deposits that become more deformed as the shelf-edge position is approached. At the shelf edge, basinward dipping, offlapping packages of soft-sediment-deformed and undeformed strata record repetitive collapse and re-establishment of shelf-edge mouth bar packages. The offlapping strata of the Karoo outcrops record progradation of the shelf margin through accretion of the shelf-edge delta, for over 1 km before subsequent transgression. The Eocene Northern Santos Basin shelf margin, in contrast, exhibits instability features which remove kilometers-wide wedges of the outer shelf that are transported to the basin floor to be deposited as mass-transport packages. In this example, shelf-edge progradation is achieved through „stable. accretion of mixed turbidites and contourites. The data also emphasize the importance of the role of shelf-edge delta processes in the delivery of sediment to the basin floor. A global dataset of 29 examples of shelf-edge systems strongly indicates that river domination of the shelf-edge system (as read from cores, well logs or isopach maps) serves as a more reliable predictor of deep-water sediment delivery and deposition than relative sea level fall as traditionally read in shelf-edge trajectories or sequence boundaries. / text

Background: Children in South Africa are still affected by micronutrient deficiencies and children living in farm communities are especially vulnerable. African Leafy Vegetables (ALVs) are well endowed with micronutrients such as iron, zinc and vitamin A and might contribute to the nutritional status of children. However, these vegetables have been perceived as “poor people’s food” and over the years knowledge of and use of ALVs has decreased. Aim: This study assessed the potential contribution of ALVs to the nutritional status of children in a semi-rural farm community. Method: In this cross-sectional study, anthropometric indices, serum iron, zinc and retinol concentrations were determined in school children aged 5−13 years (n=155). Dietary intake of iron, zinc and vitamin A was evaluated by three 24-hour diet recalls of children (n=154). The iron, zinc and β-carotene content of selected ALVs was determined. Knowledge of and use of ALVs by primary caregivers was established using focus group discussions (FGDs). Descriptive statistics, independent t-tests, the Pearson Chi-Square Test and Mann-Whitney U Test were used. Anthropometric data were analysed using the World Health Organization Reference 2007 data. Dietary data were analysed using FoodFinder (version 3). Qualitative data from FGDs were translated, transcribed and color-coded to generate emerging themes. Results: Stunting (11%) was the most prevalent anthropometric indicator of malnutrition. This was supported by the low socio-economic status of households. Deficiency prevalence in iron (serum ferritin <15 μg/L; 15.5%) and vitamin A (serum retinol <20 μg/dL; 3.2%) was low. Zinc deficiency was the most prevalent (serum zinc <65 μg/dL; 74.8%) deficiency. Median dietary intake of iron, zinc and vitamin A was generally above the Estimated Average Requirement. ALVs were potentially good sources of iron, zinc and β-carotene and could contribute substantially to the Recommended Dietary Allowance for these nutrients in children, without taking into account inhibiting factors that might affect the bioavailability. Iron content of the ALVs studied ranged from 1.4−3.2 mg/100 g edible portion. Amaranthus cruentus was the best source of iron. Zinc content of the ALVs ranged from 0.7−1.4 mg/100g edible portions, with Cleome gynandra having the highest zinc composition. The β-carotene content of the ALVs ranged from 182−314 μg RAE/100 g edible portion, with both Amaranthus cruentus and Cleome gynandra being the best sources. Knowledge of ALVs and their use was indigenous and was transferred between generations. Caregivers had positive attitudes towards the use of ALVs. Conclusion: Although the prevalence of deficiencies was not severe (with exception of zinc deficiency), micronutrient deficiencies exist in the rural farm community studied. ALVs are potentially good sources of iron, zinc and β-carotene and might contribute to the nutritional status of school children. Knowledge of ALVs and the positive attitude and perceptions regarding their use by primary caregivers implied a potentially positive future response to interventions promoting consumption of ALVs in order to contribute to the alleviation of micronutrient deficiencies. / Thesis (MSc (Nutrition))--North-West University, Potchefstroom Campus, 2013.

Background: Children in South Africa are still affected by micronutrient deficiencies and children living in farm communities are especially vulnerable. African Leafy Vegetables (ALVs) are well endowed with micronutrients such as iron, zinc and vitamin A and might contribute to the nutritional status of children. However, these vegetables have been perceived as “poor people’s food” and over the years knowledge of and use of ALVs has decreased. Aim: This study assessed the potential contribution of ALVs to the nutritional status of children in a semi-rural farm community. Method: In this cross-sectional study, anthropometric indices, serum iron, zinc and retinol concentrations were determined in school children aged 5−13 years (n=155). Dietary intake of iron, zinc and vitamin A was evaluated by three 24-hour diet recalls of children (n=154). The iron, zinc and β-carotene content of selected ALVs was determined. Knowledge of and use of ALVs by primary caregivers was established using focus group discussions (FGDs). Descriptive statistics, independent t-tests, the Pearson Chi-Square Test and Mann-Whitney U Test were used. Anthropometric data were analysed using the World Health Organization Reference 2007 data. Dietary data were analysed using FoodFinder (version 3). Qualitative data from FGDs were translated, transcribed and color-coded to generate emerging themes. Results: Stunting (11%) was the most prevalent anthropometric indicator of malnutrition. This was supported by the low socio-economic status of households. Deficiency prevalence in iron (serum ferritin <15 μg/L; 15.5%) and vitamin A (serum retinol <20 μg/dL; 3.2%) was low. Zinc deficiency was the most prevalent (serum zinc <65 μg/dL; 74.8%) deficiency. Median dietary intake of iron, zinc and vitamin A was generally above the Estimated Average Requirement. ALVs were potentially good sources of iron, zinc and β-carotene and could contribute substantially to the Recommended Dietary Allowance for these nutrients in children, without taking into account inhibiting factors that might affect the bioavailability. Iron content of the ALVs studied ranged from 1.4−3.2 mg/100 g edible portion. Amaranthus cruentus was the best source of iron. Zinc content of the ALVs ranged from 0.7−1.4 mg/100g edible portions, with Cleome gynandra having the highest zinc composition. The β-carotene content of the ALVs ranged from 182−314 μg RAE/100 g edible portion, with both Amaranthus cruentus and Cleome gynandra being the best sources. Knowledge of ALVs and their use was indigenous and was transferred between generations. Caregivers had positive attitudes towards the use of ALVs. Conclusion: Although the prevalence of deficiencies was not severe (with exception of zinc deficiency), micronutrient deficiencies exist in the rural farm community studied. ALVs are potentially good sources of iron, zinc and β-carotene and might contribute to the nutritional status of school children. Knowledge of ALVs and the positive attitude and perceptions regarding their use by primary caregivers implied a potentially positive future response to interventions promoting consumption of ALVs in order to contribute to the alleviation of micronutrient deficiencies. / Thesis (MSc (Nutrition))--North-West University, Potchefstroom Campus, 2013.

Mastering the physical aspect of piano technique has long been a topic of great interest and importance to pianists. This is borne out in the numerous pedagogical approaches on the topic of piano technique. Despite the many contributions from pedagogues and scholars in developing an understanding of piano technique, many conflicting approaches often cause more confusion than clarity. After reviewing the literature on pedagogical approaches to piano technique, this study determined that problematic language might lie at the root of the confusion. Core concepts identified in the review of literature as recurring areas of misunderstanding were tension, relaxation, co-contraction, arm weight, and hand and finger shape. The purpose of this study is to seek where issues of language exist in contemporary piano pedagogical approaches and to show how these problems may contribute to the systemic confusion in piano technique. To do this, the language that is used to describe and define the core concepts identified in the review of literature is analyzed in five modern pedagogical approaches. Five authors who have developed approaches that reflect current trends in piano technique have been selected for this study: Barbara Lister-Sink; Dorothy Taubman; Thomas Mark; Fred Karpoff; and Alan Fraser. The first step of this study entails collecting data from each of the five pedagogical approaches. The data is then analyzed for consistency and accuracy. Problems in language that contribute to the inconsistencies and inaccuracies are examined and illustrated with material from the data collection. This study concludes by identifying the main sources of confusion in the use of language: inconsistent and inaccurate use of terms; wavering between scientific, common, and invented language; challenges in describing opposing qualities that come from tension and relaxation; and failing to discern between the individual subjective experience and the mechanics of movement. By recognizing where the problems in language exist, this study represents an important first step for the pedagogical community to reach a common understanding of the language used to describe the physical aspect of piano technique.

The importance of communication is vital in wartime. The capability of having all the position information of the allied and enemy forces in a single Tactical Information Display System (TIDS), maintains a great advantage for deciding what to do before the enemy reacts. A Naval Information Distributing System (NIDS) is developed for building an effective communication infrastructure between the war ships. In the designed network, besides the mobile platforms (ships), some fixed platforms (land stations) are used to transfer the information coming from these mobile platforms to all the other platforms. To demonstrate the performance and effectiveness of the Naval Information Distribution System, a discrete event simulation model is developed on a Geographic Information System. The goal of this thesis is to describe and experimentally evaluate an effective and feasible information sharing and routing system for Navy.

Reservoir quality of subsurface sandstones depends on the composition, texture and grain size of the initial sediments. These factors are a function of hinterland processes: tectonic setting, provenance, climate and depositional environment, and sediment transportation processes. This study focuses on a modern, dryland, fluvial deposition system from source-to-sink that aims to provide a quantitative dataset analogue to facilitate forward modelling for prediction of subsurface compositions, grain size and textures of reservoir sandstones. Umbum Creek, in the western Lake Eyre Basin of Central Australia, was selected as a small river network (~ 100km²) in order to study source-to-sink sedimentation. The provenance area was analysed using isopach maps derived from a 783 drill-hole dataset, which included stratigraphy and lithology information. Subsequently forty-three samples of different provenance lithotypes from the Umbum Creek catchment were collected for petrographic thin-section analysis. Recent sediments were then sampled from 90 strategically located stream confluences along Umbum Creek and tributaries (proximal, medial and distal subsets). A quantitative textural and compositional dataset was subsequently generated from 34 selected samples. With half-phi sieve analysis (4mm to 32 microns), and an associated petrographic description recognising 72 categories of grain composition was undertaken for each sample. The provenance analysis using isopach maps demonstrated that Palaeozoic and Mesozoic sedimentary basin evolution in the study area was controlled by northeast and northwest-trending structural elements. The regional uplift of the Peake and Denison Inliers that occurred during the Cenozoic had a significant impact on the evolution of the Lake Eyre Basin, causing changes in the provenance of Late Neogene sedimentation and on through to the present. The sink area represents a shallow intracratonic basin whereby a thin veneer of fluvial/lacustrine sediments is accumulating adjacent to a basement uplift. This study has highlighted the importance of multiple sediment provenances. Five different provenance lithotype grains were identified in the Umbum Creek modern sediments: the Gawler Craton plutonic / basement provenance (recycled) the Peake and Denison Inliers Proterozoic volcanic provenance (recycled), the Davenport Ranges metamorphic provenance, the Mesozoic sedimentary provenance and the Cenozoic sedimentary provenance. Whereas a downstream fining of grain size was expected, a general trend of downstream coarsening of grain size was noted being the result of aeolian deflation of fines and intra-basinal coarse-grained sediment contributions. In the sink area, modern sediments from the terminal splay complex comprise 70-80% quartz, 10-20% lithic fragments (of which ~ 7% are ductile lithic grains), < 3% feldspar, and clay (<2%). Grains are sub-angular to well-rounded and moderately well sorted. The compositional and textural maturity of the terminal splay sediments is attributed to reworked plutonic quartz grains, the dissolution and disintegration of feldspar and carbonate grains during transportation, along with the breakdown of lithic fragments due to fluvio-aeolian interactions and subsequent mechanical/ chemical weathering processes. These data were used to build a predictive forward model for modal sandstone analysis that achieved a fair to good correlation between predicted and observed grain lithotypes and provenance categories. These results illustrate that the character of sands in the Umbum Creek catchment are governed by a multiplicity of controls such as tectonic setting, provenance lithotype analysis, climate, regional topographic gradient, hinterland transport distance, basin subsidence rate and depositional environment. The fluvio-aeolian depositional environment along with the current arid to semi-arid playa climatic conditions of Umbum Creek catchment facilitate the growth of clay coatings, however accounts for a low clay matrix within the deposits. In addition, the playa environment also facilitates the alteration of infiltrated detrital clay to kaolinite, the formation of evaporites (gypsum, halite and anhydrite) and the formation of authigenic clays. These factors are all significant in determining the ultimate reservoir quality of reservoir sandstones, emphasising the importance of this study as an analogue for modelling ‘buried’ dryland depositional systems. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1337211 / Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2008