A Unified Correlation for Slip Factor in Centrifugal Impellers.

A method that unifies the trusted centrifugal impeller slip factor prediction methods o

A concentrating solar power value proposition for South Africa

Concentrating solar power (CSP) offers the potential for a high degree of localization and an alternative strategy to meet electricity demand for South Africa in a future of uncertain conventional resources. The integrated resource plan (IRP) makes strides to introduce renewables to the electricity generation system by 2030, but we argue that the proposed energy mix is too reliant on resources that are not only unsustainable but also at risk in the short to medium term. Coal and other conventional resources may be more limited than originally anticipated, which if true, requires action to be taken soon. CSP is currently the only sustainable and dispatchable energy technology that could domestically supply a significant portion of South Africa’s electricity needs. A balanced mix of PV, wind and CSP can provide the energy supply needed in South Africa, but steps are required soon to take advantage of the localization potential and excellent sustainable energy resources

Removal of non-CO2 greenhouse gases by large-scale atmospheric solar photocatalysis

Large-scale atmospheric removal of greenhouse gases (GHGs) including methane, nitrous oxide and ozone-depleting halocarbons could reduce global warming more quickly than atmospheric removal of CO2. Photocatalysis of methane oxidizes it to CO2, effectively reducing its global warming potential (GWP) by at least 90%. Nitrous oxide can be reduced to nitrogen and oxygen by photocatalysis; meanwhile halocarbons can be mineralized by red-ox photocatalytic reactions to acid halides and CO2. Photocatalysis avoids the need for capture and sequestration of these atmospheric components. Here review an unusual hybrid device combining photocatalysis with carbon-free electricity with no-intermittency based on the solar updraft chimney. Then we review experimental evidence regarding photocatalytic transformations of non-CO2 GHGs. We propose to combine TiO2-photocatalysis with solar chimney power plants (SCPPs) to cleanse the atmosphere of non-CO2 GHGs. Worldwide installation of 50,000 SCPPs, each of capacity 200 MW, would generate a cumulative 34 PWh of renewable electricity by 2050, taking into account construction time. These SCPPs equipped with photocatalyst would process 1 atmospheric volume each 14–16 years, reducing or stopping the atmospheric growth rate of the non-CO2 GHGs and progressively reducing their atmospheric concentrations. Removal of methane, as compared to other GHGs, has enhanced efficacy in reducing radiative forcing because it liberates more °OH radicals to accelerate the cleaning of the troposphere. The overall reduction in non-CO2 GHG concentration would help to limit global temperature rise. By physically linking greenhouse gas removal to renewable electricity generation, the hybrid concept would avoid the moral hazard associated with most other climate engineering proposals

Erratum: Corrigendum: Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution

International Chicken Genome Sequencing Consortium. The Original Article was published on 09 December 2004. Nature432, 695–716 (2004). In Table 5 of this Article, the last four values listed in the ‘Copy number’ column were incorrect. These should be: LTR elements, 30,000; DNA transposons, 20,000; simple repeats, 140,000; and satellites, 4,000. These errors do not affect any of the conclusions in our paper. Additional information. The online version of the original article can be found at 10.1038/nature0315

Exploring family functioning from a family resilience perspective

South African families in semi-urban townships experience more significant stress than other families. Family resilience refers to the factors or processes within families that support them to be resilient before, during or after a stressful situation. The aim of this research was to identify the key processes contributing to the successful coping of family units, when faced with adverse conditions in Mamelodi. This study is based on the theoretical framework of family resilience proposed by Walsh (2003), namely the Family Resilience Framework (FRF). Three key processes relevant to family resilience have been identified in the FRF and include: family belief systems, organisational patterns and communication processes. These processes may reduce the stress and vulnerability of families in high-risk situations and they are therefore relevant to ascertain whether the identified processes remain applicable in semi-urban communities. Furthermore should richer family information be derived by means of the FRF, more appropriate community interventions could be developed. It is anticipated that this study will contribute to prevailing literature on family resilience as well as the limited research done in semi-urban contexts. The study population comprised 13 families that were part of an intervention programme (2012) for families living in adverse conditions in the township of Mamelodi. The client files of the 13 families were broadly analysed where after one family was interviewed (unstructured interviews) in order to retrieve more in-depth information. The family was chosen as a case study for this research. By exploring the family’s own perspectives as well as their meaning-making processes related to their seeming familial strengths, more in-depth information was derived. Due to the qualitative nature of this study, the data sources (client files, interview transcriptions, photographs and photograph descriptions) were analysed by means of thematic content analysis. Themes were then discussed with the family in order to compare and confirm the suggested findings. Results which emerged qualitatively allowed for the identification of family resilience processes in South African families in semi-urban communities as well as risk and protective factors evident in Mamelodi. As a result a better understanding of the family resilience processes in semi-urban communities could assist with better service delivery for families facing various adversities.Mini-dissertation (Med)--University of Pretoria, 2015.tm2015Educational PsychologyMedUnrestricte

<B>Laminar Separation Bubble Prediction with CFD</B>

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<B>Stall Considerations in Solar Chimney Turbines</B>

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System analysis and optimisation of the cirstel tail boom

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<B>Comparison of Solar Resource Assessments for South Africa</B>

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