Wind power variability and power system reserves in South Africa

Variable renewable generation, primarily from wind and solar, introduces new uncertainties in the operation of power systems. This paper describes and applies a method to quantify how wind power development will affect the use of short-term automatic reserves in the future South African power system. The study uses a scenario for wind power development in South Africa, based on information from the South African transmission system operator (Eskom) and the Department of Energy. The scenario foresees 5% wind power penetration by 2025. Time series for wind power production and forecasts are simulated, and the duration curves for wind power ramp rates and wind power forecast errors are applied to assess the use of reserves due to wind power variability. The main finding is that the 5% wind power penetration in 2025 will increase the use of short-term automatic reserves by approximately 2%

Signal processing with Levy information

Levy processes, which have stationary independent increments, are ideal for modelling the various types of noise that can arise in communication channels. If a Levy process admits exponential moments, then there exists a parametric family of measure changes called Esscher transformations. If the parameter is replaced with an independent random variable, the true value of which represents a "message", then under the transformed measure the original Levy process takes on the character of an "information process". In this paper we develop a theory of such Levy information processes. The underlying Levy process, which we call the fiducial process, represents the "noise type". Each such noise type is capable of carrying a message of a certain specification. A number of examples are worked out in detail, including information processes of the Brownian, Poisson, gamma, variance gamma, negative binomial, inverse Gaussian, and normal inverse Gaussian type. Although in general there is no additive decomposition of information into signal and noise, one is led nevertheless for each noise type to a well-defined scheme for signal detection and enhancement relevant to a variety of practical situations.Comment: 27 pages. Version to appear in: Proc. R. Soc. London

The Vocal Traditions of two Indigenous Cultures of South Africa

I have selected only two groups from the vastly differing groups of people in the Southern African society and will deal with each in an individual manner as the sociological, philosophical and musical practise of the music is so diverse. I will deal with the CAPEMALAYvocal tradition first as it is very close to my heart because the secular repertoire is sung in my mother tongue. It is music that originated on South African soil when the Malays were brought by the Dutch Colonists to the Cape as slaves. The second vocal tradition is that of the Xhosa! people, one of the many black traditions in South Africa, and constitutes 76.6% of the Eastern Cape population, where I now live

Towards a sustainable society: a profile of social accents

Against the background of the pending global environmental crisis, this article argues that the solutions to the crisis are as much part of the sociopolitical field as they are of the technological and scientific fields. Consequently a number of social accents that should be addressed in the attempt to achieve a sustainable society are elucidated. These accents include revision of current value systems characterized mainly by economic variables, the curbing of population growth rates, expansion of human rights, alleviation of poverty, universal access to education, health sen’ices and family planning. The redistribution of and access to natural resources, community involvement and the fostering of a political will to address these issues should also be reflected o

Short-term relationships between winter temperatures and cardiac disease mortality in Cape Town

No Abstract

Precise Model-Free Spline-Based Approach for Magnetic Field Mapping

Untethered magnetic manipulation has found applications in a rapidly increasing number of fields, ranging from minimally invasive surgery to assembly of industrial micro electromechanical systems. Despite this relevance, present-day literature on precise magnetic mapping is sparse, especially for magnetic fields affected by external disturbances. In this work, we address this deficiency by introducing a model-free mapping technique. Remarkably, the presented spline-based approach is capable of addressing the presence of inhomogeneous static disturbances and the mapping of non-azimuthally symmetric electromagnets. The work is validated with the mapping of nine metal-core electromagnets in the presence of inhomogeneous static disturbances. A grid of 5120 measurements is collected, by a custom-programed robotic arm, and used for mapping. Further, the values predicted by the approach are compared against 3430 independent field measurements, obtaining an R 2 value of 0.9884 and maximum relative errors of 7%. Overall, this spline-based approach provides a flexible technique for the precise mapping of electromagnetic fields and gradients even when, for reasons regarding coil shape or disturbances, the electromagnetic field does not present any axial symmetry

Speech-language therapy treatment practices for multilingual speakers with aphasia : a scoping review

Thesis (MSL&HT)--Stellenbosch University, 2021.ENGLISH SUMMARY : The management of multilingual aphasia, a multi-layered phenomenon, is a growing and complex field in speech-language therapy. Researchers and clinicians are often faced with many challenges and questions when making clinical decisions. The decision-making process includes the following considerations: which language(s) to treat; the transfer of therapeutic benefits between the treated and untreated language(s), or not, and whether there is little or no effect in the untreated language. Despite demographic and epidemiological trends such as increased migration patterns and the linguistic diversity in South Africa (11 official languages), a comprehensive inquiry regarding clinical practices employed by speech-language therapists (SLTs) with multilingual speakers with aphasia has not been conducted yet. Given the limited clinical guidelines available for managing this clinical population, this scoping review was conducted to explore, describe, and summarise reported speech-language therapy treatment practices used with multilingual speakers with aphasia. The scoping review included two phases. Phase one was a literature review investigating international trends in the treatment of multilingual speakers with aphasia (step one to step five). This was followed by the consultation phase (step six) in the form of semi-structured interviews with five South African SLTs working with adult multilingual speakers with aphasia. Content analysis was the primary means of analysis with a quantitative approach in phase one and a qualitative approach in phase two. The scoping review revealed a range of information regarding treatment practices for multilingual speakers with aphasia. There was variability in the practices employed and broad definitions of the terminology used. The primary concern in the stakeholder consultation process was the mismatch between the linguistic diversity amongst SLTs and most of the multilingual population in South Africa. The need for including interpreters in clinical work was also noted. These findings highlight the need to develop local research that includes evidenced-based guidelines regarding treatment practices for multilingual speakers with aphasia, despite the complexity and challenge of the heterogeneous composition of South Africa.AFRIKAANSE OPSOMMING : Meertalige afasie is 'n verskynsel met baie fasette en die behandeling daarvan is ’n groeiende en ingewikkelde proses. Navorsers en klinici het dikwels vrae wat kliniese besluitneming kan beinvloed. Die besluitnemingsproses behels onder andere die volgende: watter taal/tale om te behandel; die oordrag van terapeutiese voordele tussen die behandelde en onbehandelde tale, al dan nie, en of daar min of geen effek in die onbehandelde taal voorkom. Ten spyte van uiteenlopende demografiese en epidemiologiese neigings, soos verhoogde migrasiepatrone en die taalkundige diversiteit (11 amptelike tale) in Suid-Afrika, is daar tot op datum nie 'n omvattende ondersoek gedoen rakende kliniese praktyke wat deur spraak-taalterapeute by die meertalige bevolking gebruik word nie. 'n Oorsigstudie is aangewend om bestaande behandelingspraktyke vir spraak-taalbehandeling wat by meertalige sprekers met afasie gebruik word, te ondersoek, te beskryf en op te som. Die oorsigstudie het twee fases ingesluit. Fase een was ’n literatuuroorsig wat internasionale tendense vir die behandeling van meertalige sprekers met afasie ondersoek het (stap een tot stap vyf), gevolg deur 'n reeks semi-gestruktureerde onderhoude (stap ses) met vyf Suid-Afrikaanse spraak-taalterapeute wat betrokke was by die rehabilitasie van volwasse meertalige sprekers met afasie. Inhoudsanalise was die primêre metode van analise met 'n kwantitatiewe benadering in fase een en 'n kwalitatiewe benadering in fase twee. Die oorsigstudie het 'n verskeidenheid aspekte aangaande die behandelingspraktyke vir meertalige sprekers met afasie aangedui met verskillende resultate, asook 'n gebrek aan gedefinieerde besonderhede. Die primêre kommer wat tydens die konsultasieproses geopper is, was die wanbalans tussen die taalkundige diversiteit onder spraak-taalterapeute en die meerderheid van die veeltalige bevolking in Suid-Afrika. Daar is ook kennis geneem van die behoefte om tolke by kliniese werk in te sluit. Hierdie bevindings beklemtoon die behoefte aan plaaslike navorsing wat bewysgebaseerde riglyne rakende behandelingspraktyke vir meertalige sprekers met afasie insluit, ondanks die kompleksiteit en uitdaging van die heterogene samestelling van Suid-Afrika.Master