Carrier recovery for 49 quadrature partial response signals

Published ArticleA reference carrier signal should be regenerated from a received partial response (PR) signal in order to facilitate optimal demodulation of the received signal. This paper describes the development and evaluation of such a carrier recovery system using DSP techniques. The relative phase of a free-running local oscillator at the receiver is synchronized with the carrier signal of a received 49 quadrature partial response signal (49QPRS). Synchronization is achieved and maintained by means of a process of cross-correlation

Thermal process and novel control methods for spin-casting

Published ArticleThe quality of spin casting products and mould life are critically dependent on thermal conditions they undergo. In order to improve the performance of production and to optimise the spin-casting process, characteristics of the thermal process was firstly identified by means of the measurement and simulation. Furthermore the investigation of the developed control methods, including the thermal property substitute method and mixture method of the metal powder, was kept on the effect of air-cooling induced automatically from the spinning of the mould on the thermal process. The air cooling system was developed to optimise the thermal process during casting, utilising a theoretical analysis of the air-flow characteristics in a cooling tube submerged in a silicon mould and the characteristics of convection heat transfer associated with the mould and cast part. A numerical simulation of the casting process was also adopted in the analysis. The effect of the developed system on the thermal process was determined experimentally and it was found that a system of aircooling, automatically induced from the spinning of the mould, is feasible in optimisation of the thermal process. The developed control methods can be applied to the practice of spin casting individually or collectively according to the specific situations and requirements

Short term load forecasting using neural networks

Published ArticleSeveral forecasting models are available for research in predicting the shape of electric load curves. The development of Artificial Intelligence (AI), especially Artificial Neural Networks (ANN), can be applied to model short term load forecasting. Because of their input-output mapping ability, ANN's are well-suited for load forecasting applications. ANN's have been used extensively as time series predictors; these can include feed-forward networks that make use of a sliding window over the input data sequence. Using a combination of a time series and a neural network prediction method, the past events of the load data can be explored and used to train a neural network to predict the next load point. In this study, an investigation into the use of ANN's for short term load forecasting for Bloemfontein, Free State has been conducted with the MATLAB Neural Network Toolbox where ANN capabilities in load forecasting, with the use of only load history as input values, are demonstrated

Wavelets and short time fourier transforms on ultrasonic doppler signals for pregnancy determination in sheep

Published ArticleThe reproductive status of animals is of utmost importance to the modern farmer. Decisions concerning the management of the flock are influenced by the knowledge of the percentage of animals that are pregnant at any specific time. The aim of the project was to gain knowledge for the development of an instrument that is affordable and with which a farmer can do pregnancy determination himself/herself, thereby enabling him/her to make the correct management decisions. Experimental data were obtained from pregnant Dorper ewes with the aid of a portable Doppler instrument. Using real data as input, simulations of Wavelet and Short Time Fourier Transforms (STF) were done in MathCAD. In the simulations known levels of noise were added to the Doppler signals. Satisfactory results were obtained from the simulations of Wavelet Transforms. In the simulation of the Wavelet Transforms, signals with a SNR of -6.5 dB were successfully identified. It can thus be concluded that Wavelet Transforms can be used successfully for the detection of the fetal heartbeat in noisy ultrasonic Doppler signals

Automated component-handling system for education and research in Mechatronics

Published ArticleMechatronic practitioners are engaged in the assembly and maintenance of complex machines, plants and systems in the engineering sector or in organisations which purchase and operate such mechatronic systems. Mechatronics, often described as the synergy of mechanical and computer systems together with electronic technologies, is increasingly being singled out as a core focus by both the education and business sectors. This international trend is also evident in South Africa and Engineering Faculties now have to provide students with the opportunity not only to acquire theoretical knowledge in Mechatronics but also to develop skills in implementing and designing mechatronics systems

Modelling as Research Methodology

Modelling as Research Methodology is written for the scientist and student researching the (expected) functioning of systems under specified conditions. As such, it represents an introduction to the use of modelling in natural, human and economical sciences. The book is divided into two sections. The first section illustrates the universal nature of modelling as aid to the researcher. In the second section, several typical examples of modelling are described

Modelling as Research Methodology

Modelling as Research Methodology is written for the scientist and student researching the (expected) functioning of systems under specified conditions. As such, it represents an introduction to the use of modelling in natural, human and economical sciences. The book is divided into two sections. The first section illustrates the universal nature of modelling as aid to the researcher. In the second section, several typical examples of modelling are described

The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251○ ≤l ≤ 358○ and 2○ ≤l ≤ 61○ at |b| ≤ 1 5). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8″ and a broadband RMS sensitivity of ∼10–20 μJy beam−1. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908–1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE H II region candidates are not true H II regions; and a large sample of previously undiscovered background H I galaxies in the Zone of Avoidance

A reconfigurable AGV with omni-directional sensing

Published ArticleAutomatic guided vehicles are being used increasingly in a manufacturing environment. Developing a platform that could be easily reconfigured is perhaps a desirable option for a user with low capacity outputs. The research described in this article concentrates on such a vehicle and the development of the actuators and sensors for navigation and proper functionality