ResearchSpace

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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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First record of acid sulfate soils in a southern African Ramsar estuarine lake

(2025-11) Adams, JB; Penaluna, J; Lakane, CP; Riddin, T; Rishworth, GM; Turner, D; Van Niekerk, Lara; Lemley, DA

Rewetting of acid sulfate soils (ASS) that had prevailed after prolonged drought conditions between 2016 and 2021 caused acidification of the Verlorenvlei Estuarine Lake Ramsar site. ASS had not been recorded previously in South African estuarine systems. Historical aerial photographs revealed large areas of orange ASS visible in 2019 and 2020. In late 2021 the main lake basin of Verlorenvlei was highly acidic (pH < 3.5). After water levels increased in June 2023 following high winter rainfall, the pH of the water column in the main lake increased but remained acidic (pH ~ 4). Despite initial buffering of the pH (pH ~ 6.5) during high freshwater inflow and open mouth conditions in September 2023, the water column returned to an acidic state by February 2024 (pH ~ 4.7) once the mouth closed and water levels receded. Coupled to these water column observations, analyses revealed highly acidic (pH < 4) and sulfate-rich conditions in exposed soils during low water levels. Similarly, pyrite and jarosite both occurred in exposed soils in the middle reaches of the Verlorenvlei Estuarine Lake during the drying out phase characterised by extremely low water levels. These minerals are indicative of the presence of ASS that have become exposed and oxidised. The acidic conditions recorded in this study pose a threat to biodiversity and the Ramsar status of this estuarine system and is likely to impact surrounding livestock and agriculture. This study is globally relevant as climate change and freshwater abstraction pressures increase.

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A web scraping approach towards cryptocurrency investigations

(2025-06) Mawhayi, B; Botha, Johannes G; Leenen, L

The investigation of cryptocurrency crimes is still in its infancy with no standardised process or methodology to follow. This paper describes research that forms part of a broader project led by the second author (Botha, et al., 2025). The broader project’s aim is to develop a methodology to follow when conducting cryptocurrency crime investigations. One of the steps in the proposed methodology is web scraping. The authors of this paper present a detailed exploration of web scraping techniques within the broader context of the proposed investigation methodology. In this paper, the focus is on developing a well-structured methodology for scraping social media platforms and online forums to gather data related to fraudulent activities; the goal is to find posts that include references to the wallet address of interest. This exploration uses an iterative approach; for every new cryptocurrency wallet address discovered or revealed through on-chain analysis, a parallel path is followed by scraping the Internet. If a mention of the cryptocurrency address should be discovered it is considered to be a key finding, creating a pivot point in the investigation. From a pivot point, further open-source intelligence (OSINT) techniques will be applied, though this aspect falls beyond the scope of this paper. If no relevant information or link is found, the scraping path will not be pursued, and the investigation proceeds with on-chain analysis to identify additional wallet addresses. Additionally, challenges encountered in web scraping, such as handling platform restrictions, ensuring data accuracy, and managing large volumes of data, are addressed. The goal of the proposed methodology is to enhance data extraction and analysis efficiency contributing to the proposed methodology for investigating cryptocurrency scams.

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Precision measurement and sustainable assessment in milling of additively manufactured TiC–Ti64-ELI composites

(2025-09) Ross, NS, NS Tema; Tema, P; Masina, Bathusile N; Lekoadi, Paul M; Mashinini, PM; Ananth, MBJ , MBJ Rai; Rai, R; Nag, A

The quality of the machined surface and reduced carbon footprint are crucial factors for the operational effectiveness and lifetime of the manufactured components. Direct energy deposition (DED) can be employed to create large and complex metal parts, but low-dimensional accuracy usually requires finishing by a subtractive process. The present work deals with the sustainability assessment and machinability analysis in the machining of laser-melted titanium-based composites (TiC–Ti64-ELI) for the aviation sector. In this regard, the milling experiments were performed under distinct environmentally friendly cooling conditions. The results were analyzed in terms of environmental concerns, such as carbon emissions and specific cutting energy, as well as machining quality characteristics, including surface roughness and tool wear. The results indicate that cryogenic cooling with the carbon dioxide (Cryo-CO2) technique with laser-melted titanium composites can significantly lower carbon emissions while maintaining high-quality performance standards required in aviation applications. The desirability function was employed to obtain the best speed-feed combinations and environmental conditions for milling TiC–Ti64-ELI. The derived optimal conditions are Vc = 60 m/min, fr = 0.082 mm/rev, and Cryo-CO2 cooling. In addition, sustainable assessment was employed to study the effectiveness of environmental conditions.

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Enhancing digital wallet security: A systematic comparison of passwordless and risk-based authentication approaches

(2025-12) Mthethwa, Sthembile N; Ndhlovu, Nomalisa; Myaka, Zanele S; Ntshangase, Sthembile N; Shadung, Lesiba D; Singano, Zothile

The dynamic nature of the digital landscape necessitates robust security measures for the use of digital wallets, with authentication being pivotal in ensuring both user safety and system integrity. Traditionally, password-based authentication has been the predominant method employed. However, it is also the primary target for cyber attackers, with numerous successful breaches resulting from compromised credentials. Despite the availability of alternative methods, passwords continue to be the preferred choice. This paper examines various authentication techniques—such as passwordless, behavioral, continuous, and adaptive authentication—emphasizing their respective advantages and disadvantages. Additionally, it discusses the challenges associated with the implementation of these methods and outlines key considerations for organisations prior to adoption. Specifically for digital wallets, passwordless and risk-based authentication methods are identified as the most appropriate. Future research will focus on testing and comparing the effectiveness of these two methods by simulating attacks to determine which provides greater security.

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Embedded systems design of a low-cost flight controller for use in UAV platforms

(2025-09) Fraser, D; Pretorius, A; Hepworth, J; Botha, Natasha

Serving as a critical interface between high-level software and low-level electronic systems, flight controllers are essential for aerial robotic applications. However, their significant cost poses a barrier to widespread adoption. While affordable, off-the-shelf flight controllers exist, they generally do not support the firmware required for research- and industrylevel implementation, such as PX4. This paper presents embedded system designs for low-cost flight controllers that are PX4 compliant. The research delves into examining the necessary components, existing open-source firmware/software, and appropriate hardware solutions. The presented designs are based on open standards and capable of operating with various platforms, applications, and components. The final design is shown to be low in cost while also demonstrating substantial potential for integration with existing applications. The flight controllers were verified with a range of tests, including the implementation of a control system that was responsible for governing the roll angle of a quadcopter. The overall flight controller performance is shown to be comparable with the performance and functionality of commercial solutions.