Thermochromic energy-efficient windows have been investigated intensively ever since the rise of an energy-efficient model for VO2-based windows. However, pure VO2 possesses an energetic difference of low-to-high-temperature infrared transmittance lower than 10% and visible transmittance at about 40%, which limits its commercial application as a coating material for smart...
High Temperature Reactors (HTRs), particularly the very high temperature reactor (VHTR), represents a significant advancement in nuclear reactor technology. Reactors operate at temperatures exceeding 1000 °C, which enhance the thermal efficiency and allow the potential for hydrogen production through thermochemical processes. In a VHTR, the generated impurities in the helium coolant can lead...
We present a browser-based simulation tool for Surface Plasmon Resonance (SPR) sensor modelling, developed using Python and Flask. The tool allows users to visualize reflectance curves based on selected or custom parameters, incorporating Drude models for metals and experimentally validated refractive index equations for biological media such as plasma and blood. Users can generate real-time...
In large-scale particle physics experimentation, maintaining precise control of diverse environmental parameters across complex detector subsystems constitutes a fundamental operational requirement, directly impacting data acquisition integrity, component longevity, and systemic stability. Contemporary slow control infrastructures predominantly employ static threshold parameters, deterministic...
ABSTRACT
Electricity usage and demand has risen tremendously over the years and so has its price. This has resulted in the need for less expensive, viable and ecologically acceptable means of producing energy for electricity. Currently, the primary source of electricity and power in South Africa is sourced from fossil fuels which has impacts on global warming. Bongumusa Secondary School in...
The High Luminosity Large Hadron Collider (HL-LHC) is scheduled to commence operations in 2030, targeting a luminosity five times than that of the current LHC run. This substantial increase in luminosity necessitates significant upgrades to the LHC detector systems. The Phase-II upgrades of the ATLAS detector involve a complete upgrade to the low voltage power supply (LVPS) system of its Tile...
The rapid expansion of the solar photovoltaic (PV) sector has brought increasing attention to the sustainable management of decommissioned solar panels. This study investigates circular economy strategies for addressing the environmental and material recovery challenges associated with end-of-life (EoL) PV modules. Drawing on a review of current practices and policy frameworks, the paper...
In this study, we present a comparative analysis of deep neural networks (DNN) and XGBoost for the classification of γγ+τ final states to separate rare signal events from background using Monte Carlo data. The dataset is preprocessed to exclude energy-related features and focus on the kinematic variables of the first identified tau lepton (τ₁). A DNN model is a machine learning model that...
Sodium-ion batteries (SIBs) represent a cost-effective and sustainable alternative to lithium-ion batteries, especially in the context of large-scale energy storage applications. This study utilized first-principles calculations grounded in density functional theory (DFT) with a spin-polarized generalized gradient approximation (GGA + U), applying a U value of 4.0 eV for all transition metals....
Waste-to-energy conversion is contributing significantly in enhancing the economic growth and health quality in society. One of the technologies that utilized waste-to-energy transformation is biomass technology. The study focused on the development of a nonlinear multiple regression (response surface) model to predict the biogas production with input parameters being relative pH of slurry,...
Biogas, as a renewable energy source, has gained attention due to its potential to reduce greenhouse gas emissions and provide sustainable alternatives to fossil fuels. However, its widespread adoption is hindered by challenges such as low methane (CH4) content and corrosive impurities such as hydrogen sulphide (H2S), which limit its efficiency and application. This...
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...
The global shift towards sustainable energy highlights the importance of supplying electricity to rural regions through renewable energy microgrids. Community development centres, such as the Masia Development Centre in Limpopo, South Africa, play a crucial role in community development and local economic growth. However, they often face challenges related to unreliable or insufficient power...
Equilibrium and elastic properties of hexagonal molybdenum disulphide (MoS2) are investigated using the full-potential all electrons linearised augmented plane wave method. Generalized gradient approximation of Perdew-Burke-Ernzerhof for solids (GGA_PBE_Sol) was chosen to calculate equilibrium electronic structure and elastic properties. Electronic band structure and density of states results...
Titanium Nickel (TiNi) alloys are widely used in biomedical and aerospace applications due to their unique shape memory effect and superelastic properties. However, their susceptibility to corrosion in aggressive environments limits their long-term performance and reliability. Understanding the surface stability of TiNi is crucial for developing strategies to enhance corrosion resistance and...
We are inspired to study the K2SbAu ternary compound using first-principles methods based on density functional theory (DFT) to advance the optoelectronic technology. This comprehensive study predicts structural, electronic, elastic, mechanical, and optical properties. The lattice parameters of the K2SbAu ternary compound were in agreement with the experimentally observed...
The growing global energy crisis necessitates the search for sustainable and environmentally friendly alternatives to fossil fuels. In this study, first-principles Density Functional Theory (DFT) calculations were employed to investigate the structural, electronic, optical, and mechanical properties of the all-inorganic perovskite compound CsPbI₃, a promising material for clean energy...
Tungsten (w) is considered as the potential plasma facing material for fusion reactor application due to its exceptional mechanical and thermal properties. The notable properties of tungsten are its high melting point, high thermal conductivity, hardness, and low sputtering yield. However, tungsten also presents a very low fracture toughness limiting its application as plasma coating material....
The threats posed by climate change have been reported to be driven by use of fossil fuels. Therefore, to effectively mitigate these challenges, there is need of transitioning to renewable energy sources such as solar and wind. A critical component of this transition is developing energy storage devices that not only match but exceed the energy and power densities of fossil fuels. Batteries...
Polyanionic phosphate-based materials have gained significant interest as cathode materials for sodium-ion batteries (SIBs) owing to their intrinsic thermal stability, structural integrity, and elevated operating voltage. This study employed first-principles density functional theory (DFT) computations with the generalized gradient approximation (GGA + U) in Materials Studio, applying an...
The development of sodium-ion battery (SIB) technology relies on the development of high-performance cathode materials. Ithis study investigates the structural, electrical, and electrochemical properties of Ni-doped NaMnPO3F cathodes (NaMn1-xNixPO3F, 0 < x < 0.5) through the first-principles calculations based on density functional theory (DFT). The simulations conductedin this study show a...
Understanding the impact of radiation on detector components is essential for ensuring the sustained long-term performance of the ATLAS TileCal, particularly in the high-luminosity phase of the LHC. This study details a variety of FLUKA Monte Carlo simulations investigating the effects
of gamma irradiation on selected materials used in the dynode chain of photomultiplier tubes, a vital...
We performed water adsorptions on the PtSb2 (100) surface, where H2O was adsorbed through oxygen on top of the surface Pt and Sb atoms. The (100) surface was explored by increasing the number of H2O on the surface. The (100) surface was explored by increasing the number of H2O on the surface. Lastly, the full-surface coverage (16/16 H2O/Sb, Pt) was investigated where all Pt and Sb were...
In this study, we combine simulation and topological analysis techniques to identify and study cosmic filaments. We employ the Simba-C simulation, a large-volume hydrodynamic cosmological simulation that incorporates dark matter, baryonic matter, and chemical enrichment, to produce a representative slice of the Universe. To detect filamentary structures within this simulated data, we utilize...
The production of high-quality radioisotopes is essential for nuclear medicine, scientific research and various industries. These radioisotopes are produced using advanced particle accelerators at iThemba LABS and have become the leading organization for radioisotope production. The process requires precise control over the beam parameters, the target material, and the chemical processing....
Abstract
The ongoing issue of community blackouts due to load reduction and shedding needs urgent solutions. These power interruptions disrupt daily life and affect supply and demand dynamics. The root of the problem is the high cost of electricity and annual tariff increases. As a result, some customers resort to illegal connections, theft, and meter tampering to reduce their...
As technology advances, ionizing radiation has become an essential tool in various fields such as medicine, industry, and research. However, excessive exposure poses serious health risks, including cancer. This study investigates the radiation shielding properties of heavy metal oxide (HMO) glasses to provide safer, lead-free alternatives for X-ray and gamma-ray protection. A series of glasses...
Over the past decade, photovoltaic water pumping system (PVWPS) concept failed to perform optimally due to its complexity of multiple systems that run together. Lack of access to real-time data caused poor system’s performance and ultimately ceased to supply the solar energy to pump the water. Therefore, a system to integrate and manage the multi-systems nexus of PV solar power output, water...
Sensors based on Low Gain Avalanche Diode (LGAD) technology enable high precision timing and position measurements. Paired with a high radiation hardness as well as low production costs, LGAD sensors represent excellent candidates for in-beam detectors, such as beam structure monitoring, but also for various tracking applications. They are currently used for both ATLAS and CMS experiments for...
Be X-ray binaries (BeXBs) are a subclass of high-mass X-ray binaries consisting of a Be star and a compact object, typically a neutron star. The Be star features a Keplerian disc, known as a "decretion" disc, in its equatorial regions. This disc is thought to form due to the star's rapid rotation. The interaction between the decretion disc and the neutron star leads to the accretion of matter,...
In this work, we aim to compute the radio flux from the decay of axions close to Saggitarius A, the supermassive black hole at the center of our galaxy. These particles can undergo stimulated decay in the presence of photons with energies of half the axion mass. We make use of an observed spectrum for Sgr A emission in the frequency range of SKA and the VLBA, to find the effect of stimulated...
In this work simulations of the interaction of a stellar wind with the interstellar medium, which forms an astrospheric cavity, are presented. Results are shown where the astrosphere of Lambda Cephei is simulated for three different scenarios, corresponding to three different ISM speeds. The results can be visualized as density contour plots as well as radial profiles for different simulation...
From the rich soil of Tshivhase tea estate in Thohoyandou, blooms the green fields of Midi tea plantation and processing units. This delicious and locally produced black tea is largely available locally and open for market anywhere in the world. The increase in demand for storage devices prompted researchers to consider other possible, low cost and commercially viable alternatives to meet the...
This study examines the contribution of hybrid energy systems to achieving carbon neutrality in South Africa's power sector by integrating solar, wind, and hydroelectric resources. Employing the IRENA FlexTool, the study examines various hybrid system configurations to evaluate their efficiency in reducing reliance on fossil fuels while ensuring grid stability. This study investigates the...
The ATLAS inner tracker (ITK) proposed for the upgrade is divided into the strips, outer pixels and inner pixels, each with its own complexities and inbuilt systems. The outer pixel is sandwiched between the strips and the inner pixel. It is flushed with N₂ from the inlet to the outlet to maintain the dryness of the outer pixels. However, specific temperature, humidity and dew point...
ABSTRACT
Neonatal jaundice, also known as neonatal hyperbilirubinemia, is a common condition among newborns in the first week after birth. Notable, it is a leading cause of death and disability for newborns in low-resource nations, including Southern Africa nations. Persistent challenges due to inadequate, inefficient or financially inaccessible diagnostic alternatives for its management in...
Nuclear Forensic Science (NFS) plays a crucial role in enhancing nuclear security, primarily through the detection and attribution of illicit nuclear materials. However, its application in nuclear waste management remains underexplored. Inadequate disposal and poor tracking of nuclear waste pose significant environmental and public health risks, especially in regions with limited regulatory...
Dye-sensitized solar cells (DSSCs) are photovoltaic devices that provide high solar to electric energy conversion efficiency through light sensitization of metal oxides by adsorbed dyes. Recently, considerable research has focused on enhancing the efficiency of DSSCs by improving individual elements of the device. Among all the elements, porous TiO2 thin-films sensitized with light-absorbing...
South Africa, with abundant renewable energy resources, is undergoing a significant transition as it strives to integrate renewable energy into its energy mix to meet the country’s growing demands sustainably. However, the efficient utilization and integration of renewable energy sources into the grid poses several technical, economic, and regulatory challenges. This research proposes a...
The growing demand for electricity in off-grid regions, combined with rising global energy needs driven by population growth, underscores the urgent need to explore renewable energy alternatives to fossil fuels key contributors to carbon emissions and climate change. Wind energy offers a sustainable option but is challenged by its variability and low-speed performance in certain regions. This...
As South Africa grapples with ongoing energy shortages and rising demand, hybrid renewable energy microgrids have emerged as an effective and scalable approach for supplying power to off-grid and rural communities. This study, which explores the performance of a hybrid microgrid that integrates photovoltaic (PV) panels, fuel cells, and battery storage systems, plays a crucial role in providing...
Computational magnetohydrodynamics (MHD) provides a powerful framework for modelling matter in extreme environments where both fluid dynamics and magnetic fields are critical. These conditions arise in heavy-ion collisions (HIC) and astrophysical events like core-collapse supernovae (CCSNe). To ensure solver accuracy, we validate our RMHD model using a piston-driven shock wave test problem,...
The global shift towards sustainable energy highlights rural electrification via renewable energy microgrids. In South Africa, agricultural development centres are crucial for ensuring food security and fostering rural economic growth, yet they frequently struggle with unreliable electricity access. Understanding the energy consumption patterns of these facilities is essential for effective...
Lung cancer has highest mortality rate of all cancers worldwide and this is due to late detection of the disease. Current diagnostic techniques are invasive and expensive resulting in late diagnosis. Exhaled human breath offers an alternative rapid and non-invasive technique. This is because human breath has volatile organic compounds (VOCs) some which can be biomarkers of certain diseases....
The Phase-II upgrades focus on enhancing the Tile Calorimeter's capabilities in ATLAS detectors, essential for high-energy physics research. Led by Wits University, these upgrades involve improving LVPS bricks, which convert 200V DC to 10V DC for detector operations, ensuring radiation resistance and reliability. Over a thousand LVPS bricks will be produced, each undergoing initial and final...
Real-time monitoring and control are essential in particle physics environments, where experimental precision depends not only on instrumentation stability but also on the well-being of personnel. Technicians and physicists at CERN often work long hours on sensitive detector systems within confined spaces, where elevated CO₂ levels can impair cognitive function and reduce operational...
Variable stars are stars whose brightness varies with time when observed from Earth. The change in brightness may
be due to changes in star’s luminosity, and obstructions in the amount of light that reaches Earth. Studying variable
stars helps understand stellar evolution and properties. The project aims to search for and classify variable stars using
photometric time-series data from the...
The target star of this research, HD68695, has characteristics of a young star with its age estimated to be about 7.3 million years by Arun et al. 2019. Murphy et al. 2020 observed strong emission in H-β, concluding that HD 68695 did not appear to be a λ-Böotis star and therefore its membership in the class was uncertain. Furthermore, Murphy et al. 2020, and Medupe et al. (2019) using...
We study the role of Parton Distribution Functions (PDFs) in calculating cross sections of Drell-Yan processes in proton-proton collisions at $\sqrt{s} = 13.6$ TeV. The theoretical production cross-sections of W$^\pm$ and Z bosons are calculated via their muonic decay channel using POWHEG and PYTHIA8 event generators. The contributions from each parton's PDF are explicitly shown in the...
Often extracted from an ore with a grade ranging between 25 and 35%, phosphorus is an important element in fertilizers, medicines, selected chemical compounds, cleaning products, steels, animals’ food and sensor devices. In addition to the physical magnetic and chemical concentration methods, direct concentration by flotation of phosphorus bearing minerals is employed. With an emphasis on the...
We investigated the dependence of particle ratios on collision energy in Pb+Pb high-energy heavy-ion collisions using the Ultra-relativistic Quantum Molecular Dynamics model (UrQMD-3.4). This latest model version incorporates charmed particles (e.g., D, $J/\psi$, $X_{c}$), crucial in understanding particle production mechanisms and the chemical freeze-out of hadronic matter. Our simulations...
The Technology Innovation Platform (TIP) at iThemba LABS, South Africa's national facility for accelerator-based sciences, aims to transform our nuclear and particle physics research into practical applications. We've set up TIP around several key technology projects in detector systems, data acquisition, specialised fabrication, and control interfaces. The work will include thick GEM...
ABSTRACT:
The transforming growth factor-beta (TGF-β) pathway is a pivotal regulator in directing adipose-derived stem cells (ADSCs) toward tenogenic lineage, making it a vital focus in tendon tissue engineering. Concurrently, photobiomodulation (PBM) has gained attention as a non-invasive technique to influence cell behavior and support tissue repair. Its potential to interact with...
Localized surface plasmon resonance (LSPR) phenomenon occurs when incident light of specific wavelength excites the free electrons on the gold nanoparticles surface, which then leads to the enhancement of the nanoparticle surface electromagnetic field. The enhanced electromagnetic field has a short decay length and is localized in LSPR as opposed to the surface plasmon resonance (SPR) where...
Atmospheric monitoring systems play a crucial role in tracking weather conditions and assessing air quality, which is essential for both climate research and public health. While ground-based monitoring systems provide valuable localized data, they are limited in their ability to capture measurements at higher altitudes. Balloon-borne systems offer a solution to this gap, enabling the...
This research focuses on more than 15,000-millimetre wavelength sources observed using the Atacama Cosmology Telescope. These sources cover an area of approximately 18,000 square degrees and the ACT data observed at 98 GHz allows us to have a large population of AGNs at different redshift bands. This makes it possible to study the light these AGNs released at a redshift of up to 4.5,...
While Dark Matter (DM) is treated as a single substance in contemporary astrophysics research, the process whereby this DM paradigm has been established is a complex one, involving both theoretical contributions and astronomical observations. In defining this paradigm, we trace the growth in the number of citations since publication for a number of seminal papers. These include theoretical...
We investigate the evolution of the infrared–radio correlation (q$_{\rm IR}$) as a function of redshift (z) and stellar mass (M$_∗$ ) for star-forming galaxies (SFGs) in the COSMOS field, using MIGHTEE Early Science data. We use radio-detected galaxies with multi-wavelength counterparts to classify sources as radio-quiet AGN (RQ AGN), radio-loud AGN (RL AGN), and SFGs over the redshift range 0...
The migration of silver (Ag) and strontium (Sr) ions co-implanted into polycrystalline silicon carbide (SiC) in the presence of helium (He) was studied using Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy (TEM). 360 keV Ag ions were first implanted into SiC, followed by...
University of Johannesburg contributes 25% to the final design of the Tile Pre-Processor Modules for the ATLAS Tile Calorimeter at the High-Luminosity Large Hadron Collider (HL-LHC). This work focuses on the status of the Tile Computer-on-Module (TileCoM) and the Tile Gigabit Ethernet Switch (Tile GbE) in terms of firmware, software and hardware integration. The procurement of 62 Xilinx FPGAs...
Abstract
The stimulated luminescence features of aluminum oxide (Al2O3) regulated by defects and impurities within the structure are well-known. Examples of resultant applied materials include Al2O3:C and Al2O3:C,Mg. This study examines the basis for the experimental observation that doping Al2O3 with Mg and C improves its thermoluminescence (TL) sensitivity. In order to study the...
Organic polymers with inorganic reinforced composites are in daily use both domestically and industrially - in coating, adhesives, primers, aeronautic utilities, electro-optical devices and sensors, among others. These polymer-based materials are competing with metallic alloys in terms of cost and functionality (durability, strength, and other physical and chemical properties). However, the...
The High-Luminosity Large Hadron Collider (HL-LHC) necessitates a comprehensive electronics upgrade of the ATLAS Tile Calorimeter (TileCal) to ensure robust operation under increased radiation and data-rate conditions. To address this, the ATLAS TileCal has introduced the Phase-II upgrade, which involves a complete replacement of the existing electronic system. As part of the Phase-II upgrade,...
This research focuses on the design and development of high-resolution Time-to-Digital Converters (TDCs) and explores key parameters for evaluating their performance. Among various time-to-digital conversion methods, three approaches are examined in detail: counter-based, delay line-based (including Vernier, buffer, and inverter-based delay lines). The study specifically investigates the...
Accurate track matching is vital for reconstructing particle trajectories
in high-energy physics. In ALICE at the LHC, the upgraded muon tracking
system combines data from the Muon Spectrometer with the new Muon
Forward Tracker (MFT), a highly segmented silicon pixel detector positioned
near the interaction point before the hadron absorber. With the
MFT recording orders of magnitude more...
Graphdiyne, a carbon allotrope characterized by its unique two-dimensional structure, semiconducting behavior, and rich sp-hybridized carbon content, shows great promise for practical applications in fields such as energy storage, catalysis, and gas separation. Understanding the electronic properties of graphdiyne under tensile and compressive deformation is essential for its integration into...
Cosmological models in which dark matter and dark energy interact in a non-gravitational manner are known as Interacting Dark Energy (IDE) models and have been proposed to address many long-standing shortcomings and tensions in standard cosmology. Furthermore, recent results from the DESI Collaboration have suggested hints of dynamical dark energy, for which IDE models could provide a viable...
In Radio Astronomy there are several steps to follow to calibrate the data before it can be used for scientific research. One of these steps, specifically for a single-dish telescope like the Hartebeesthoek 26m telescope, is to do pointing observations to determine if the pointing model of the telescope is working properly. The pointing observations consists of pointing the telescope at the...
The search for new physics is one of the key goals of the ATLAS Collaboration. With the discovery of the Higgs boson in 2012, the Standard Model (SM) gained an essential ingredient towards the understanding of fundamental particles and their interactions – but it cannot yet be considered complete. The nature of Dark Matter (DM), which constitutes about 27% of the Universe, remains a major open...
Rural regions are largely reliant on non-renewable energy sources and frequently experience energy shortages. Alternative renewable energy sources like wind energy must be investigated to lessen dependency on fossil fuels and advance sustainability in these areas. This study evaluates wind energy potential in nearby locations by examining wind speed, direction, and flux data gathered using a...
