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The tree Acacia mearnsii is native to south-eastern Australia but has become an aggressive invader in many countries. In South Africa, it is a significant threat to the conservation of biomes. Detecting and mapping its early invasion is critical. The current ground-based methods to map A. mearnsii are accurate but are neither economical nor practical. Remote sensing (RS) provides accurate and repeatable spatial information on tree species. The potential of RS technology to map A. mearnsii distributions remains poorly understood, mainly due to a lack of knowledge on the spectral properties of A. mearnsii relative to co-occurring native plants. We investigated the spectral uniqueness of A. mearnsii compared to co-occurring native plant species within the South African landscape. We explored full-range (400–2500 nm), leaf and canopy hyperspectral reflectance of the species. The spectral reflectance was collected biweekly from December 23, 2016 and May 31, 2017. We conducted a time series analysis, to assess the effect of seasonality on species discrimination. For comparison, two classification models were employed: parametric interval extended canonical variate discriminant (iECVA-DA) and nonparametric random forest discriminant classifiers (RF-DA). The results of this paper suggest that phenology plays a crucial role in discriminating between A. mearnsii and sampled species. The RF classifier discriminated A. mearnsii with slightly higher accuracies (from 92% to 100%) when compared with the iECVA-DA (from 85% to 93%). The study showed the potential of RS to discriminate between A. mearnsii and co-occurring plant species. [ABSTRACT FROM AUTHOR]

In this paper, laboratory-based bidirectional reflectance distribution function (BRDF) analysis of vegetation leaves, soil, and leaf-litter samples is presented. The leaf litter and soil samples, numbered 1 and 2, were obtained from a site located in the savanna biome of South Africa (Skukuza: 25.0° S, 31.5° E). A third soil sample, number 3, was obtained from Etosha Pan, Namibia (19.20° S, 15.93° E, altitude of 1100 m). In addition, BRDF of local fresh and dry leaves from tulip polar tree (Liriodendron tulipifera) and black locust tree (Robinia pseudoacacia) were studied. It is shown how the BRDF depends on the incident and scatter angles, sample size (i.e., crushed versus whole leaf), soil samples fraction size, sample status (i.e., fresh versus dry leaves), vegetation species (i.e., poplar versus locust), and the vegetation's biochemical composition. As a demonstration of the application of the results of this paper, airborne BRDF measurements acquired with NASA's Cloud Absorption Radiometer over the same general site where the soil and leaf-litter samples were obtained are compared to the laboratory results. Good agreement between laboratory and airborne-measured BRDF is reported. [ABSTRACT FROM AUTHOR]

This paper reports on an investigation into the incidence of plagiarism in the context of a new university of technology in South Africa. The findings indicate that plagiarism can take many forms, some of which are a result of dishonesty and academic misconduct, while others are related to the educational levels and cultural diversity of the faculty and student body. The paper argues that a "one-size-fits-all" approach to plagiarism is not likely to be effective within a context of development and change, different forms of plagiarism should be clearly identified, and different institutional responses are necessary to address these items. [ABSTRACT FROM AUTHOR]

This paper describes the application of the abrupt change detection technologies to detect the abrupt changes in the signals recorded during disturbances in the electrical power network of South Africa for disturbance analysis and relay performance monitoring. The aim is to estimate the time instants of the changes in the signal model parameters during the prefault condition, after initiation of fault, after the circuit-breaker opening and autoreclosure, etc. After these event-specific segmentations, the synchronization of the different digital fault recorder recordings are done based on the fault inception timings. The synchronized signals are segmented again. This synchronized segmentation is the first step toward automatic disturbance recognition, facilitating further complex feature vector analysis and pattern recognition. Besides, the synchronized, segmented recordings can be directly used to analyze certain kinds of disturbances and monitor the relay performance. This paper presents many practical examples from the power network in South Africa. [ABSTRACT FROM AUTHOR]

This paper describes how HIV/AIDS education is being introduced into the curriculum of the Department of Electrical, Electronic, and Computer Engineering at the University of Pretoria, Pretoria, South Africa. Third- and fourth-year students were provided with an HIV/AIDS Educational CD developed at the university. Their knowledge of the subject was tested via two quizzes -- one written before they were exposed to the material on the CD and one after. In addition, a mathematical HIV/AIDS model is being incorporated into a third-year control systems course. This model is used to illustrate standard control systems engineering concepts, such as linearization, system stability, feedback, and dynamic compensation. This paper is an example of how topical nonengineering material can effectively be made part of a high-level undergraduate engineering course. Students benefit not only from the topical nature of the subject, hut also from an improved understanding of control engineering concepts which can be applied to many different fields. [ABSTRACT FROM AUTHOR]

In South Africa, the need exists for a long-term monitoring system to detect deformation because of mining. Differential radar interferometry (dInSAR) is recognized for its ability to detect deformation without the need for extensive field observations. However, phase noise (assessed by interferometric coherence) is known to adversely affect interferometric measurements. In this paper, 12 polarimetric RADARSAT-2 SAR images are used to statistically analyze the sensitivity of coherence to perpendicular baseline, Doppler centroid (DC) difference, temporal baseline, land surface evolution, and polarization. The results suggest that the average scene coherence for HH and VV polarizations is most sensitive to the effects of temporal baseline if RADARSAT-2 data with small perpendicular baselines and DC differences are considered. However, an increase in the sensitivity to dc difference and perpendicular baseline is observed after analysis of ERS-2 data for which higher values of these parameters are available. The choice of optimal polarization is seasonally dependent, with VV polarization data being more suitable at the end of the growing season after harvesting, while HH polarization is more suitable during the peak of the growing season. Image pairs with at most 24-day temporal baselines are required during the peak of the growing season while successful interferogram generation is possible with temporal baselines of up to 120 days after the peak of the growing season. Subsidence basins are successfully detected, demonstrating that the dInSAR techniques would be suitable for the long-term monitoring of surface subsidence in this dynamic commercial agricultural environment. [ABSTRACT FROM PUBLISHER]

Technological advances have driven all aspects of Earth observation data, including improvements realized in sensor characteristics and capabilities, global data processing, near real-time monitoring, value-added products, and the distribution of global products. In particular, the growth of the World Wide Web is contributing to an increase in the global user base. The synergy of remote sensing, geographic information systems (GIS), Internet, and mobile phone technologies is revolutionizing the way in which satellite-derived information is archived and distributed to users. The Fire Information for Resource Management System (FIRMS), a NASA-funded application, is just one of many examples that illustrate the increasing ease with which Earth observation data are accessible to a broad range of users. This paper describes how the delivery of satellite-derived fire information has evolved over the last six years. By understanding user requirements and taking advantage of recent developments in areas such as information management, search, access, visualization, and enabling technologies, FIRMS has expanded the number and range of users that are able to access and utilize satellite-derived fire information. Specifically, we describe how satellite remote sensing and GIS technologies have been integrated to deliver MODIS active fire data to natural resource managers using Internet mapping services and customized e-mail alerts to users in more than 90 countries. We also describe how this web-based desktop application has been transitioned to a mobile service in South Africa to deliver fire information to field staff to warn of fires that may be potentially damaging to both natural resources and infrastructure. [ABSTRACT FROM AUTHOR]

This paper presents a dual cumulative probability distribution model for predicting the cumulative distribution of the probability that a particular value of the propagation k-factor will be exceeded. The distributions relate to so-called ‘dry’ and ‘wet’ (or ‘climatic’) components. The model is based on meteorological radiosonde data observed over a period of some 11 years and published by other workers. The model is extended by a simple height regression analysis in order to predict the cumulative behavior of the k-factor at different ground level heights in the summer rainfall area of South Africa during different months. Comparisons are made between predicted and observed data. The model may have potential applications in other parts of the world where data on k-factor behavior are scarce. [ABSTRACT FROM AUTHOR]

In this paper, a laboratory experiment, which was developed to teach undergraduate students at the University of Pretoria, Pretoria, South Africa, some of the main issues regarding closed-loop system identification, is discussed. In this experiment, a plant is identified both from open-loop and closed-loop data. The model obtained from the open-loop data is used as reference to evaluate a closed-loop system identification approach. A motivation for closed-loop system identification and a Laboratory experiment in this field is given. The experiment is outlined, each step is discussed, and the experiment is evaluated. This experiment shows that closed-loop system identification can be taught in an uncomplicated manner. [ABSTRACT FROM AUTHOR]