A process planning framework for milling of titanium alloys

Titanium alloys are being used increasingly in new generation aircraft, creating a market for high value components. It is argued that knowledge development is the key factor for South African machining suppliers to penetrate the global aerospace supply chains. This paper discusses current results of a collaborative project aiming at systematic research towards improved and more efficient utilisation of the High Speed Cutting (HSC), and particularly the High Performance Machining (HPM) technologies for selected titanium alloys. A process planning framework for milling of titanium alloys has been developed. Using as point of departure prominent tool demands, this framework combines a tool wear map approach and cost modelling that enables process planners as well as machine operators to act towards optimised machining. In this way the targeted cost minimisation and lead time shortening could be modelled and practically achieved

Investigating current smart production innovations in the machine building industry on sustainability aspects

CITATION: Waibel, M. W., Oosthuizen, G. A. & Du Toit, D. W. 2018. Investigating current smart production innovations in the machine building industry on sustainability aspects. Procedia Manufacturing, 21:774-781, doi:10.1016/j.promfg.2018.02.183.The original publication is available at https://www.sciencedirect.comENGLISH ABSTRACT: Driven by the rising demand for individualized high-tech products the machine building industry continuously introduces a wide variety of smart innovations. Manufacturing companies face growing production requirements which can only be only handled by intelligent systems. During the last decades the trend in manufacturing has shifted from the classic mass production to complex individualized products which have to be produced to compete with the costs of mass products. Smart Production Systems are characterized by its flexibility, resource efficiency, ergonomic design and the ability to integrate customer and business partner into the value creation process. This research study investigates current smart production innovations and trends in the machine building industry. The sustainability aspects and the potential of various smart innovations are outlined.https://www.sciencedirect.com/science/article/pii/S2351978918302233Publisher's versio

The effects of selective laser melting scan strategies on deviation of hybrid parts

CITATION: Hagedorn-Hansen, D., et al. 2017. The effects of selective laser melting scan strategies on deviation of hybrid parts. South African Journal of Industrial Engineering, 28(3):200-212, doi:10.7166/28-3-1862.The original publication is available at http://sajie.journals.ac.zaENGLISH ABSTRACT: The use of additive manufacturing to produce intricate part geometries in the aerospace, medical, and tool-and-die industries is increasingly incorporated in manufacturing process chains. However, the high costs, long production times, and material integrity issues associated with additive manufacturing technologies such as selective laser melting make the process suitable only for certain applications. In order to reduce selective laser melting production costs for selected parts, a combination of selective laser melting and milling can be used. Metal parts produced with this method are referred to as hybrid parts. A challenge in producing hybrid parts is to reduce the geometrical deviation due to process-induced warping. This paper discusses the effects of various laser scan strategies on the deviation of hybrid parts. A newly developed scan strategy is experimentally compared with its commercial counterpart with regard to as-built part warping and porosity. The novel strategy resulted in a significant reduction in warping and porosity.AFRIKAANSE OPSOMMING: Die benutting van toevoegingsvervaardiging vir die produksie van komplekse onderdeel geometrieë in die lugvaart, mediese, en werktuig industrieë word toenemend geïnkorporeer in vervaardigingsproseskettings. Gepaardgaande hoë kostes, lang produksietye, en materiaal integriteitstekortkominge met toevoegingsvervaardiging tegnologieë soos selektiewe laser smelting veroorsaak dat die proses slegs uitvoerbaar is vir sekere toepassings. Ten einde selektiewe laser smelting produksiekoste te verminder vir geselekteerde onderdele, kan ’n kombinasie van selektiewe laser smelting en freesmasjinering geïmplementeer word. Metaal onderdele wat met so kombinasie geproduseer word, word na verwys as hibried onderdele. ’n Uitdaging in die vervaardiging van hibried onderdele is om geometriese afwyking deur skeeftrekking wat deur die proses veroorsaak word, te verminder. Hierdie artikel bespreek die effekte van verskeie laser skandeer strategieë op die afwyking van hibried onderdele. ’n Nuut ontwikkelde skandeer strategie is eksperimenteel vergelyk met ’n kommersiële eweknie met betrekking tot skeeftrekking en porositeit. Die skeeftrekking en porositeit van die nuut uitgevonde strategie is beduidend laer.http://sajie.journals.ac.za/pub/article/view/1862Publisher's versio

Venous bicarbonate and creatine kinase as diagnostic and prognostic tools in the setting of acute traumatic rhabdomyolysis

Background. Myorenal or crush syndrome often develops following soft-tissue traumatic injury. It is a spectrum of disease that may result in severe renal dysfunction and kidney injury requiring renal replacement therapy.Objectives. To review a large cohort of patients with so-called myorenal or crush syndrome and assess the biochemical markers of venous bicarbonate and creatine kinase as predictors for the development of acute kidney injury (AKI).Methods. All patients with myorenal syndrome who presented to Khayelitsha District Hospital, Cape Town, South Africa (SA), and Ngwelezana Hospital, Empangeni, KwaZulu-Natal, SA, between January and December 2017 were identified and reviewed.Results. A total of 212 patients were included in the study. At both hospitals, 94% of the patients were male. Using the Pearson correlation coefficient, we compared creatinine kinase (CK) against serum creatinine. The mean CK level was 5 311.8 U/L and the mean creatinine level 133.457 μmol/L. The r-value was 0.2533. Although this is a technically positive correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000208. When comparing venous bicarbonate (HCO3) against creatinine, the mean HCO3 level was 22.296 mmol/L and the mean creatinine level 162.053 μmol/L. The r-value was –0.3468. Although this is a technically negative correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000013. The inverse ratio shown with HCO3 v. creatinine, although still a weak correlation, is significantly better in predicting an increase in creatinine compared with the weak positive correlation of CK v. creatinine.Conclusions. Although both venous HCO3 and CK showed a weak correlation with creatinine, the former performed significantly better in predicting AKI. In a resource-constrained system, we recommend that HCO3 be measured to assess patients with crush injury and that CK be regarded as a complementary modality

Satellite tracking of leatherback and loggerhead sea turtles on the Southeast African coastline

The waters of southeast Africa contain important habitats for several sea turtle species, including the leatherback Dermochelys coriacea, loggerhead Caretta caretta, hawksbill Eretmochelys imbricata, green Chelonia mydas, and olive ridley turtle Lepidochelys olivacea. Many of these species are of conservation concern (Rakotoniria & Cooke, 1994; Thorson et al., 2012; Nel et al., 2013) and vulnerable to regional threats such as fisheries by-catch or boat-strikes (Bourjea et al., 2008; Grantham et al., 2008; Pusineri & Quillard, 2008). To help in the development of effective conservation plans for these species, many conservation or research organisations have used satellite transmitters to help identify critical habitats for sea turtles (Harris et al., 2015; Robinson et al., 2016). Here, we review the movement patterns of sea turtles that have been tracked through satellite telemetry from their nesting beaches on the east coast of South Africa

A raised serum lactate level is an independent predictor of in-hospital mortality in patients with isolated cerebral gunshot wounds

Background. Cerebral gunshot wounds (CGSWs) represent a highly lethal form of traumatic brain injury, and triaging these patients is difficult. The prognostic significance of the serum lactate level in the setting of CGSWs is largely unknown.Objectives. To examine the relationship between elevated serum lactate levels and mortality in patients with isolated CGSWs.Methods. A retrospective review of the regional trauma registry was undertaken at the Pietermaritzburg Metropolitan Trauma Service, South Africa, over a 5-year period from 1 January 2010 to 31 December 2014. All patients with an isolated CGSW were included.Results. A total of 102 patients with isolated CGSWs were identified. Of these, 92.2% (94/102) were male. The mean age (standard deviation) was 29 (8) years, and the in-hospital mortality rate was 21.6% (22/102). The mean serum lactate level was significantly higher among non-survivors than among survivors (6.1 mmol/L v. 1.3 mmol/L; p<0.001). Lactate levels among non-survivors were <2 mmol/L in 4.5%, 2 - 3.99 mmol/L in 9.1%, 4 - 5.99 mmol/L in 36.4% and ≥6 mmol/L in 50.0%. The odds ratio for mortality with a lactate level of 4 - 5.99 mmol/L was 67 (95% confidence interval (CI) 1.7 - 2 674.2), while for a lactate level of ≥6 mmol/L it was 1 787 (95% CI 9.0 - 354 116.1). The serum lactate level accurately predicted mortality even after adjustment for other variables. Based on a receiver operating curve analysis, an optimal cut-off of 3.3 mmol/L for serum lactate as a predictor for mortality was identified (area under the curve = 0.957).Conclusions. CGSWs are associated with significant mortality, and a raised serum lactate level appears to be an independent predictor of in-hospital mortality. It is a potentially useful adjunct in the resuscitation room for identifying patients with a very poor prognosis.

Assessing the efficacy of a modified assertive community-based treatment programme in a developing country

<p>Abstract</p> <p>Background</p> <p>A number of recently published randomized controlled trials conducted in developed countries have reported no advantage for assertive interventions over standard care models. One possible explanation could be that so-called "standard care" has become more comprehensive in recent years, incorporating some of the salient aspects of assertive models in its modus operandi. Our study represents the first randomised controlled trial assessing the effect of a modified assertive treatment service on readmission rates and other measures of outcome in a developing country.</p> <p>Methods</p> <p>High frequency service users were randomized into an intervention (n = 34) and a control (n = 26) group. The control group received standard community care and the active group an assertive intervention based on a modified version of the international model of assertive community treatment. Study visits were conducted at baseline and 12 months with demographic and illness information collected at visit 1 and readmission rates documented at study end. Symptomatology and functioning were measured at both visits using the PANSS, CDSS, ESRS, WHO-QOL and SOFAS.</p> <p>Results</p> <p>At 12 month follow-up subjects receiving the assertive intervention had significantly lower total PANSS (p = 0.02) as well as positive (p < 0.01) and general psychopathology (p = 0.01) subscales' scores. The mean SOFAS score was also significantly higher (p = 0.02) and the mean number of psychiatric admissions significantly lower (p < 0.01) in the intervention group.</p> <p>Conclusions</p> <p>Our results indicate that assertive interventions in a developing setting where standard community mental services are often under resourced can produce significant outcomes. Furthermore, these interventions need not be as expensive and comprehensive as international, first-world models in order to reduce inpatient days, improve psychopathology and overall levels of functioning in patients with severe mental illness.</p

Poverty and Well-being in Post-Apartheid South Africa: An Overview of Data, Outcomes and Policy

WP 2006-03 January 2006This is an overview of poverty and well-being in the first decade of post-apartheid South Africa. It is an introduction to a volume that brings together some of the most prominent academic research done on this topic for the 10-year review process in South Africa. This overview highlights three key aspects of the picture that the detailed research paints. First, data quality and comparability has been a constant issue in arriving at a consensus among analysts on the outcomes for households and individuals in postapartheid South Africa. Second, while the outcomes on unemployment, poverty and inequality are indeed bad, the outcomes on social indicators and access to public services are much more encouraging. Third, the prospects for rapid and sustained economic growth, without which poverty and well-being cannot be addressed in the long run, are themselves negatively affected by increasing inequality, poverty and unemployment