ResearchSpace

Communities in ResearchSpace

Welcome to ResearchSpace, the institutional repository of the CSIR. ResearchSpace is an open access electronic archive collecting, preserving and distributing scholarly digital materials created by the CSIR.

Recent Submissions

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Radar detectability of light aircraft micro‐Doppler modulation

(2024-10) Berndt, Robert J; Gaffar, MYA; Nel, Willem AJ; O’Hagan, DW

The critical role of specifying micro-Doppler mode performance in the modelling and development of modern radar systems is investigated. The authors focus on the detection of micro-Doppler modulation from light aircraft, analysing data from eight helicopters and nine propeller aircraft. With the growing need for accurate target classification in radar technology, incorporating micro-Doppler detection metrics into radar performance specifications has become increasingly important. This research offers a novel approach to measuring the detectability of micro-Doppler modulation relative to returns from the main fuselage. The investigation covers the impacts of various preprocessing techniques, polarisation, and aspect angle on detection capabilities. Findings reveal that, on average, micro-Doppler modulation from propellers is detectable at distances between 50% and 100% of the range at which the fuselage is detected. For helicopters, this range decreases to between 30% and 80%. Additionally, the study introduces empirically derived statistical models designed to predict micro-Doppler detection ranges in relation to fuselage returns, enhancing the predictability and specificity of radar system performance. This novel contribution presents a basis for improving radar system specifications, leading ultimately to more predictable and reliable light aircraft classification.

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Conceptual Model for Taxation and Regulatory Governance among South African Crypto Asset Holders

(2024-12) Ramazhamba, Pardon T; Venter, HS, Pardon T

The rapid adoption of digital assets has revolutionised the global financial landscape, bringing new opportunities and challenges. In South Africa, digital asset adoption has surged, driven by economic factors and a tech-savvy population. However, this growth has outpaced regulatory development, particularly around tax compliance. This paper proposes a conceptual model aimed at addressing the non-compliance issues among crypto asset holders. The model incorporates advanced mechanisms for visualising crypto address interactions and generating crypto tax Non-Fungible Tokens as a verification tool. By mapping and monitoring crypto transactions, the model provides regulatory bodies with enhanced tools to track, verify and enforce tax obligations transparently and efficiently.

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Project management as an enabler of doctoral completion

(African Minds, 2024-12) Meyer, Isabella A; Botha, Jan; Frick, Liezel; Tshuma, Nompilo

South Africa has a population of 62 million. The country has 26 public universities with a total enrolment of 1.1 million students. Doctoral enrolments in South Africa have increased from 9 994 in 2008 to 23 588 in 2020 (CHE, Vitalstats). During the period 2000-2018, a total of 32 025 doctoral students graduated at South African universities. Annual doctoral graduates increased from 972 in 2000 to 3 339 in 2019 (SciSTIP, Tracer Study). Stellenbosch University became an independent university in 1918, tracing its origins to the Theological Seminary of the Dutch Reformed Church (est. 1859) and Stellenbosch College (est. 1880). The university has ten faculties located on four campuses (in Stellenbosch, Bellville, Cape Town and Saldanha). In 2021 it had 1 400 academic staff members and 32 471 students, including 1 611 doctoral candidates, and 310 doctoral degrees were awarded. The first doctoral degree was awarded by Stellenbosch University in 1923, in physics. The Council for Scientific and Industrial Research (CSIR) is a national research and development organisation in South Africa, established in 1945. The CSIR undertakes directed, multidisciplinary research and technological innovation that contributes to the improved quality of life of South Africans. The CSIR’s shareholder is the South African Parliament, held in proxy by the Minister of Higher Education, Science and Innovation.

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Earth Observation support for water quality monitoring in estuaries 2025

(2025-03) Smith, Marié A

Focus on development of EO products and services that support applications relating to water quality, harmful algal bloom detection, and coastal ecosystem monitoring.

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Effects of earth metal dopants on the properties of a neodymium magnet using a first-principles approach

(2025-03) Miya, L; Sithole, E; Modiba, Rosinah

Rare-earth (RE) ions enhance the stability of permanent magnets against demagnetization, making them vital in wind turbines, electric vehicle engines, magnetic resonance imaging machines, and cell phone devices. However, the rising costs and dwindling reserves of RE materials necessitate the development of RE-free permanent magnets for a sustainable economy. This study uses first-principles calculations to investigate the magnetic properties and electronic structure of RE2Fe14B (RE = Nd, Dy, Y, La, and Ce). Spin-polarized density functional theory, using the generalized gradient approximation and Perdew–Burke–Ernzerhof function, was performed to predict the properties of RE2Fe14B permanent magnets. The study found that the spin and orbital magnetic moments of Nd, Dy, Y, La, and Ce atoms are opposite, consistent with Hund’s rule, with the total orbital magnetic moment exceeding the total spin magnetic moment. Y prefers the 4f site, while La prefers the 4g site. Ce showed specific magnetic moments at the 4f and 4g sites, contributing oppositely to the total magnetic moment. Substitutions of nonmagnetic La and Ce reduced the total magnetic moments of the cells. The bandwidth of the Fe d states in La2Fe14B is shorter than those of the Nd, Dy, Y, and Ce structures because the lattice parameter of La2Fe14B was greater than those of all of the other structures. The findings align well with previous experimental and theoretical data, indicating that substituting Dy, Y, La, and Ce affects the properties of permanent magnets, where Ce has the highest magnetic moments and Dy has the highest Curie temperature compared to the other RE substitutes.