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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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Impact of Improper Battery Management System Design for Lithium-Iron- Phosphate Batteries

(2025-10) Thakoorden, Renesh R; Mabeo, Reuben T; Hlalele, Thabo G

This paper presents an experimental investigation into the impact of Battery Management System (BMS) design on the performance and reliability of Lithium-Iron Phosphate (LiFePO4) batteries. The original objective of this study was to determine the State-of-Health (SoH) of three commercially available LiFePO4 batteries under a selected test protocol. The experimental results showed that the integrated BMSs in all three tested brands exhibited erratic and unpredictable behaviour in their charge and discharge current limits. The initial hypothesis was that the behaviour is directly linked to the overall battery temperature due to the heating during charging and discharging however, no discernible relationship could be determined. Tne observation was the premature shutdown of the batteries as depicted by the sharp current drops. The BMSs shutdown and disconnected the battery from the test equipment thereby ceasing the test. The tests were restarted and the data stitched together to be able to conduct an analysis. This highlights a flaw in the design or implementation of these “off-the-shelf” BMSs, as they limit the optimal operation of these batteries. This study demonstrates that improperly designed and implemented Battery Management Systems can affect battery performance. While the original scope of the tests was to determine SoH, the observed BMS behaviour prevented this assessment, shifting the focus to the critical impact of these design deficiencies.

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Dynamic deformation behavior of the TM380 mild steel subjected to blast

(2025-06) Shoke, Lerato S; Sono, Tleyane J; Mutombo, Kalenda; Snyman, IM

The dynamic deformation behavior of the mild-steel TM380 subjected to explosive loading has been investigated. An imparted impulse and high pressure, from a PE4 explosive charge, interacted with the plate which is attached to a deflection gauge designed to measure the mid-point deflection time history and the imparted impulse. The shape of the bulge at the midsection of the plate was that of a paraboloid. The deflection-time curve is characterized by an escalation, followed by a very short plateau of a few microseconds at mid-point deflection, and finally a drop in deflection timespan. The dynamic strain, strain rate and impulse changes are revealed by deflection-time, velocity-time and hydrostatic pressure curves. Although no significant change in grain size and morphology occurs after shock wave loading, the pearlite lamellar structure transformed into spheroidized cementite as a result of shock induced phase transformation.

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Southern Ocean summer warming is regulated by storm-driven mixing

(2025-12) Du Plessis, MD; Nicholson, Sarah-Anne; Giddy, I; Monteiro, PMS; Prend, CJ; Swart, S

The Southern Ocean absorbs most of the excess heat resulting from climate change. However, climate projections show a persistent warm summer bias in its sea surface temperatures, indicating a limited understanding of the air–sea heat exchange mechanisms governing this region. Here we examine the impact of storms on the interannual variability of Southern Ocean surface temperatures during summer using in situ observations from underwater and surface robotic vehicles, climate reanalyzes and satellite data. We show that synoptic-scale storms regulate summer sea surface temperatures through alteration of the effective heat capacity of the mixed layer and the entrainment of colder water from below. Storms reduce the summer ocean heat gain by limiting solar radiation reaching the surface. This effect is partially offset by a reduction in heat loss due to turbulent air–sea exchange. We also find that interannual variations in sea surface temperature during summer in the Southern Ocean are driven by changes in storm-mean wind speeds, which are linked to the Southern Annular Mode. Our results demonstrate a causal link between storm forcing and sea surface temperature variability, which is critical for reducing warming biases in climate models and improving future climate projections.

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Evaluating the efficacy of hybrid deep learning models in assessing temporal night-time light trends for the cities of Cape Town, Durban and Johannesburg in South Africa

(2025-01) Mncube, Z; Xulu, S; Mbatha, Nkanyiso B

Introduction: Increasing research demonstrates the value of nighttime light (NTL) data for studying human activities, including urban change. The public availability of these products on geospatial computing platforms like Google Earth Engine (GEE) has expanded their use for various applications and adding incorporation of Python and R analysis tools. Methods: Deep learning techniques such as Wavelet Denoise (WD), Empirical Mode Decomposition (EMD), and Enhanced Empirical Mode Decomposition (EEMD) are seldom used in NTL research, but here were used them with long short-term memory (LSTM) to form hybrid models to denoise and decompose NTL trajectory to interpretable frequency levels and intrinsic mode functions (IMFs) that improve trend evaluation. We leveraged these tools to assess the performance of deep learning models in modelling and forecasting NTL trends in Cape Town, Durban, and Johannesburg from 2014 to 2023. Root mean square error (RMSE) and mean absolute error (MAE) were used to evaluate model performance. Results: The findings indicate that integrating decomposition approaches with LSTM enhances the precision and interpretability of NTL modelling. In Cape Town, the RMSE for all models varied from 0.083 to 0.114, while the MAE ranged from 0.063 to 0.085. Durban, RMSE ranged from 0.069 to 0.133, and MAE varied from 0.055 to 0.108. Johannesburg, RMSE ranged from 0.124 to 0.449 and MAE varied from 0.102 to 0.383. Discussion: Because of decomposition advantages, EEMD-LSTM hybrid model showing superior efficacy in Cape Town and Johannesburg, whilst EMD-LSTM model excelled in Durban.

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Enhancing water permeability in thin-film nanocomposite membranes utilizing electrospun recycled PET and graphene oxide

(2025-02) Zamisa, Mantsopa K; Sinha Ray, Supraka; Madirisha, MM; Ojijo, Vincent O; Seadira, T; Sadiku, RE; Kumar, Neeraj; Orasugh, Jonathan

Addressing the challenge of low permeability in Thin-Film Nanocomposite (TFNC) membranes is crucial for improving water filtration efficiency. Despite advancements in membrane technology, the interface between the substrate and active layer remains a critical research gap affecting overall permeability. This study aims to fill this gap using electrospun recycled polyethylene terephthalate (rPET) substrates combined with graphene oxide (GO). A vacuum-assisted self-assembly method was employed to coat microporous rPET substrates with GO. Extensive characterization techniques, including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), x-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analyses, demonstrated the uniform GO layer formation on rPET substrates, indicating enhanced structural and operational efficiency. The integration of GO resulted in a crystalline structure modification, improved surface morphology, and increased water permeability. The optimized rPET-GO membranes showcased a significant decrease in water contact angle to approximately 93 degrees, denoting enhanced hydrophilicity and, consequently, better permeability compared to uncoated rPET membranes. Despite increased hydrophilicity, the membranes exhibited reduced but stable permeability rates, highlighting the effectiveness of the GO and rPET blend in advancing membrane functionality. These findings mark a significant advancement in membrane technology, offering enhanced water permeability efficiency and paving the way for a substantial impact on sustainable water management. Additionally, this study underscores the importance of recycling in developing advanced materials for environmental applications.