REACH is a joint venture between the University of Cambridge and Stellenbosch University in South Africa. With primary funding for hardware and logistics from the Kavli Foundation (through the Kavli Institute for Cosmology in Cambridge) and Stellenbosch University, REACH will be deployed in the Karoo region of South Africa, a unique Radio Frequency Interference (RFI) quiet site that is also home to the Square Kilometer Array telescope. The team has conceived the basics of the proposed system over a period of 2 years and is now in the next phase – construction and the ultimate deployment and operation over the period 2020-2021 (taking into account a probable delay due to the COVID-19 pandemic). The Big Bang model is a theory mapping out the origin and evolution of the Universe and has, over time, become a well-studied field of research. It facilitated a better understanding of the subsequent theory of evolution, over billions of years, of stars and other celestial objects. However, less is known about the period spanning approximately 0.35 to 1 billion years after the assumed Big Bang. According to the theory, during this time, the Universe transitioned from “being a vast volume filled with a cooling neutral gas” to a realm of cosmic objects observable from Earth.
The global demand for energy is rapidly increasing each year. In fact, BP’s Statistical Review of World Energy indicates that “[p]rimary energy consumption grew at a rate of 2.9% … almost double its 10-year average of 1.5% per year, and the fastest since 2010” moving even further away from the accelerated transition envisaged by the Paris climate goals. It has, therefore, become crucial to develop and utilise alternative techniques to meet global energy needs. To facilitate a global energy transition to the clean, sustainable and eco-friendly generation of electricity, the energy sector continuously searches for ways to shift the world to a low-carbon economy; promoting energy-efficient techniques through renewable energy sources for reducing the world’s dependence on fossil fuels. Floating photovoltaic systems, as discussed in this article, are one such technique. We have compiled a table of contents for ease of navigation: Background What are floating photovoltaic systems and how do they work? Conclusion
The current COVID-19 pandemic has sparked a controversial debate around whether radio frequencies such as the latest 5G communication band can be connected to human illness or disease. Most of the claims made online stems from the fact that radio waves are technically radiation. Radiation is more often than not viewed in a negative light without realising that not all radiation is bad and that a distinction should be drawn between ionizing and non-ionizing radiation. Two of the most prevalent questions are: Can viruses be transmitted through electromagnetic energy and can electromagnetic energy transmitted at these frequencies penetrate the human body or alter it in any significant way? In this article, we consider the 5G phenomenon as well as, to our current knowledge, the effect of 5G signals on the human body.
1. Introduction and objectives The ability to accurately forecast energy usage has become progressively more important, especially in the current South African milieu. An interest in energy conservation within today’s energy-conscious society has also grown rapidly. In addition, increased public awareness and political pressure resulted in a universal push to “move away from carbon-emitting energy supplies”. Schools are but one scenario where this has become topical. The problem, however, is that the “current techno-economic sizing of [photovoltaic] PV solutions for schools in South Africa rely on hourly smart meter measurements, costly equipment and scarce skills.” Schools are currently billed on commercial and industrial tariff structures, and by reducing their energy usage and maximum monthly demand, the money saved can be utilised towards improving the quality of education delivered. The recent reductions in PV costs and the convenient concurrence of insolation and schools’ energy usage have piqued interest in enhancing supply with solar PV to save on energy costs and so unburden the grid in developing countries. Furthermore, with the recent advances in PV technology, the costs of the actual solar panels have reduced dramatically. In response, the Department of Electric and Electronic Engineering presented a novel approach to forecast schools’ hourly demand using only monthly utility bills and a trained forecasting model by (1) developing a computationally low-cost, accurate forecasting model using easily accessible input parameters, (2) using the forecast to develop a method capable of adequate load-matching using a solar model, (3) combining the thermal-storage capabilities of EWHs with load-matched solar through smart-scheduling techniques to decrease peak monthly demand and basic energy usages, and (4) providing accurate cost and savings forecasts to determine the viability of the energy-saving intervention at a particular school.
Background When harvesting the Rooibos plant, only the top 30cm of the shrub is cut off. Rooibos plants are harvested annually, and the lifecycle of a plant is between 3 to 5 years whereafter the plant dies and new Rooibos needs to be planted. It takes about 2 years for a new harvest to be ready. After being harvested, the tea is put through a chopping machine that cuts the tea into 3mm pieces whereafter the tea is spread out on a concrete slab in anticipation of its fermentation process. To properly ferment the tea, the moisture content of the tea is raised, and a heavy roller is used to bruise the tea. The tea is left to ferment overnight during which process the temperature of the fermenting tea rises to about 38 to 40°C. The last step entails spreading the tea out in the sun to dry. Thereafter the tea is sifted to remove twigs and stems and to improve the quality of the tea. The sifted product is sterilizes using steam which reaches temperatures of approximates 85 to 92°C for about 2,5 minutes or 160°C for 1,5 minutes. After sterilisation, the team is air-dried and packed for bulk storage.
Our previous post noted that for SKA2, large, electronically steerable phased arrays or “aperture arrays” are being developed for the mid-frequency band (450 – 1450 MHz). The Mid-Frequency Aperture Array (MFAA) Consortium in collaboration with Stellenbosch University, as a member of the MFAA, is tasked with developing these large systems. The MFAA forms part of the SKA Advanced Instrumentation Programme (AIP) responsible for developing the technology required to realise the aperture array concept in the mid-frequency range. The mid-frequency aperture array Thermal analysis Conclusion Furthermore, with recent advancements in low-power electronics and computing aperture arrays have become a workable option for certain frequency bands. For SKA2, the MFAA consortium is currently evaluating, amongst others, the Dense Dipole Array (DDA) developed at Stellenbosch University’s Electrical and Electronic Department, as a candidate for the MFAA. The DDA is a ground planar structure with tightly coupled dipole elements which is fed differentially through an expressly designed common-mode suppressing feed. The planar nature of the DDA structure will assist in simplifying mass-production and maintenance as many are to be deployed in the field.
In our previous post, we discussed the history of the Square Kilometre Array (SKA) project which commenced during September 1993 and is being constructed in South Africa and Australia. However, the complete vision for SKA encompasses a second phase that will see the SKA telescope become one of the most visionary science projects of the twenty-first century. The SKA will ultimately use thousands of dishes and nearly a million low-frequency antennas that will allow astronomers to observe the sky in unparalleled detail and survey the entire sky much faster than any current system. About SKA2 SKA2 aims for a significant increase in capabilities and to expand the project to other African countries ultimately seeing approximately 2 000 dishes distributed across Africa with an expanded frequency range of up to 25GHz. It will build on the work of SKA1, namely, to pursue Science Driver in greater depth and to follow up on new discoveries emerging from the SKA1 programme. For SKA2, large, electronically steerable phased arrays or “aperture arrays” are being developed for the mid-frequency band (450 – 1450 MHz). The Mid-Frequency Aperture Array (MFAA) Consortium is tasked with developing these large systems and Stellenbosch University, as a member of the MFAA, is closely involved with the project.
“I always thought something was fundamentally wrong with the universe” – Arthur Dent The Large Millimeter Telescope (LMT) is the world’s largest single-dish steerable millimetre wave telescope. The Mexican government, under the leadership of Prof Laurent Lionard of the National Autonomous University of Mexico, funded a project to investigate the feasibility of adding a K-band receiver to the telescope cabin. Prof De Villiers, of the Department of Electrical and Electronic Engineering at Stellenbosch University, in close collaboration with William Cerfonteyn, a PhD student, form part of the team who was tasked with developing an optical design of the required reflectors for this project. We have compiled a handy table of contents to help you navigate: What is the LMT? What is its objective? Progress made
The Square Kilometre Array (SKA) project was born out of an international effort to build the world’s largest radio telescope. The name derives from the fact that the telescope has over a square kilometer of collecting area. The SKA telescope is one of the largest scientific endeavours in history operating over sites in South Africa and Western Australia and as such draws the world’s finest scientists, engineers, and policymakers. MeerKAT, the South African radio telescope, is the SKA’s forerunner and will integrate into the mid-frequency component of SKA. Prof Dirk de Villiers of the Department of Electric and Electronic Engineering currently has a large research programme in this field. The history of the SKA project The SKA project commenced during September 1993 with the International Union of Radio Science’s (URSI) establishment of the Large Telescope Working Group. This heralded a worldwide effort to develop scientific goals and technical specifications for a next-generation radio observatory. After various meetings of the working group and the ratification of various memoranda pertaining to the SKA project, it is now led by the SKA Organisation, a not-for-profit company established in December 2011 to formalise relationships between the international partners.
Merriam-Webster defines “novel” as “new and not resembling something formerly known or used” and “original or striking especially in conception …”. There is no better description for the 3D printed horn antenna final year student, Kobus Kotzé, recently designed under the supervision of Dr Jacki Gilmore at the Faculty of Electrical and Electronic Engineering at Stellenbosch University. What is a waveguide? Selective Laser Melting (SLM) 3D-printing Project motivation and goal Conclusion 3D printing has been around for a number of years, yet it has only very recently been applied to the printing of waveguides and antennas. This breakthrough research has laid the foundation for a whole new field of design possibilities as in the past, waveguides were only available in limited sizes (that is, widths and heights).
