Neural networks for time series analysis

The analysis of a time series is a problem well known to statisticians. Neural networks form the basis of an entirely non-linear approach to the analysis of time series. It has been widely used in pattern recognition, classification and prediction. Recently, reviews from a statistical perspective were done by Cheng and Titterington (1994) and Ripley (1993). One of the most important properties of a neural network is its ability to learn. In neural network methodology, the data set is divided in three different sets, namely a training set, a cross-validation set, and a test set. The training set is used for training the network with the various available learning (optimisation) algorithms. Different algorithms will perform best on different problems. The advantages and limitations of different algorithms in respect of all training problems are discussed. In this dissertation the method of neural networks and that of ARlMA. models are discussed. The procedures of identification, estimation and evaluation of both models are investigated. Many of the standard techniques in statistics can be compared with neural network methodology, especially in applications with large data sets. Additional information available on two discs stored at the Africana section, Merensky Library.Dissertation (MSc (Mathematical Statistics))--University of Pretoria, 2007.Statisticsunrestricte

Evaluation of a Continuous Miner Half-Curtain Dust Control System in a South African Underground Coal Mine

The issues of public health and safety in the mining industry have been dealt with around the world through the intervention of governments. In 1997 the South African Department of Minerals and Energy (DME) sent out a directive to reduce the dust concentration level to /m3 at the operator\u27s position for the sampling period. The reasons for the difficulty with compliance are: long headings up to 35m, inherently high dust generation rates of coal, and the increased use of highly mechanized equipment. A project was formulated under SIMRAC auspices with the title of Underground Mechanical Miner Environmental Control to address the dust problem. The project was planned in two phases. The first phase involved laboratory tests on a continuous miner model for different ventilation and spray systems at the newly built ventilation simulation tunnel at the Kloppersbos research center. In the second phase of the project, tests were carried out underground, based on the findings and recommendations from the simulated tests. This paper focuses on the results and findings for the half-curtain system which has been encouraging. The average dust concentration for the sampling period at the operator\u27s position for the half-curtain system was 3.20 mg/m3. On the other hand, the equivalent average dust concentration (TWA-CONC) for the half-curtain system for an 8-h period was 2.04 mg/m3. The outcome of this project has shown that the regulatory dust level of /m3 can be achieved through close collaboration with all the interested parties

‘Goldilocks anatomy’ – data-conserving anatomy video tutorials during emergency remote teaching

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Development of guidance for sustainable irrigation use of greywater in gardens and small-scale agriculture in South Africa

Greywater is untreated household effluent from baths, showers, kitchen and hand-wash basins and laundry (i.e. all non-toilet uses). More than half of indoor household water is normally used for these purposes and can potentially be intercepted by the householder for additional beneficial uses. Greywater use is practised on an informal basis to supplement irrigation water, either in urban gardens in middle- to upper-income suburbs or in food gardens in lower-income informal, periurban and rural areas. It holds the potential to contribute significantly to food security in poor settlements by providing a source of both irrigation water and nutrients for crop plants. However, there are presently no formal guidelines for the use of greywater in South Africa. This paper presents the rationale and framework of a guidance document for the sustainable use of greywater to irrigate gardens and small-scale agriculture in South Africa, developed under the auspices of the Water Research Commission. The 3 driving principles in developing this guidance were: protection of human health; protection of plants irrigated; and protection of soil and the environment. Risk-management scenarios were developed on the basis of the extent of greywater characterisation. Water-quality constituents for inclusion were selected from among those indicated as presenting a problem in previous studies. Guidance was provided for managing greywater quality, either by mitigation of greywater quality (by practices such as irrigation method, amelioration of soil, leaching of soil and planting of tolerant plant types) or by small-scale biological treatment of greywater. Guidance was also given regarding the volumes of greywaterwhich can be applied, together with factors to adjust these volumes for site-specific conditions.Keywords: greywater, irrigation, food security, sustainable agriculture, health, soil, plant growt

Preliminary investigation into the cause of acid mine water induced seismicity in Johannesburg

A preliminary investigation was done into the possible causes of the increased seismic activity in the Witwatersrand Basin. The paper focuses on approximated underground mining areas, groundwater mobility, rock types and the proximity of fault lines to seismic events. These parameters were mapped and correlated with observed seismicity in the area. There is some indication that the presence of underground mining areas has a positive relationship with the occurrence of seismic events. The other parameters exhibit a negative relationship with seismic activity. However, more detailed investigations are required before final conclusions can be drawn. An approach to risk assessment of possible earthquake scenarios in the City of Johannesburg (CoJ) is proposed. The approach aims to assess potential damage to infrastructure and loss of life in the case of an earthquake. The results of such an assessment may provide justification for more detailed investigations

Recent advances in dust control technology on South African underground coal mines

Despite the much-heralded arrival of the new millennium, improving mine health and safety remains an enormous challenge. Considerable progress with environmental (dust and methane) control in South African mines has indeed been made but it remains a matter of great concern to all parties, i.e. mine management, labor and the government. The introduction of the 1997 Directive on dust exposure and mine ventilation was a milestone for the South African coal mining industry in improving health and safety standards. These stricter guidelines and the latest dust control technologies are beneficial not only in the longterm health perspective, but also to in terms of controlling methane and coal dust explosions (high-risk) in the short term. Over the past two years, CSIR: Miningtek personnel developed new dust control systems through various Safety In Mines Research Advisory Committee (SIMRAC) funded projects and successfully implemented them in underground coal mines. Currently, it can be confidently claimed that the new and proven dust control systems are being effectively operated in more than 80% of the bord and pillar sections in South Africa. This paper highlights the critical components of the new dust control systems evaluated underground, viz., the half-curtain system, the retrofitted hood system, the double scrubber system and the integrated hood system for continuous miners, and the road header dust control system. The status of wet head dust control systems and the challenges facing high seam longwall mines are also presented in the paper. The relative effectiveness of various dust control systems are discussed and the relevant test results are given in the paper. It concludes with a discussion of the progress made and challenges facing the coal mining industry in reducing workers’ exposure to respirable dust.SIMRAChttp://www.mvssa.co.zaam2017Mining Engineerin

Evaluation of a continuous miner half-curtain dust control system in a South African underground coal mine

The project was planned in two phases. The first phase involved laboratory tests on a continuous miner model for different ventilation and spray systems at the newly built ventilation simulation tunnel at the Klopperbos research centre. In the second phase of the project, tests were carried out underground based on the findings and recommendations from the simulated tests. This paper focuses on the results and findings for the half-curtain system which have been encouraging. The average dust concentration for the sampling period at the operator’s position for the half-curtain system was 3.20 mg/m3. On the other hand, the equivalent average dust concentration (TWA-CONC) for the half-curtain system for a 8-h period was 2.04 mg/m3. The outcome of this project has shown that the regulatory dust level of <5 mg/m3 can be achieved through close collaboration with all the interested parties.http://www.mvssa.co.zaam2017Mining Engineerin

Burden, spectrum and outcomes of children with tuberculosis diagnosed at a district-level hospital in South Africa

CITATION: Du Preez, K., et al. 2018. Burden, spectrum and outcomes of children with tuberculosis diagnosed at a district-level hospital in South Africa. International Journal of Tuberculosis and Lung Disease, 22(9):1037-1043, doi:10.5588/ijtld.17.0893.The original publication is available at https://www.ingentaconnect.com/content/iuatld/ijtldSETTING: The Khayelitsha subdistrict has the highest burden of reported tuberculosis (TB) cases in Cape Town, Western Cape Province, South Africa. OBJECTIVES: To characterise the TB burden, spectrum and treatment outcomes among children managed at a district-level hospital, the Khayelitsha District Hospital. DESIGN: Retrospective medical record review of all children (age <13 years) diagnosed with TB in January–July 2014. A lay health care worker completed daily surveillance and supported linkage to TB care. Symptoms and investigations at presentation, TB disease spectrum, referral pathways and outcomes were reported. RESULTS: Most children were aged ≤2 years (84/99, 85%), 18/96 (19%) were infected with the human immunodeficiency virus, 31/91 (34%) were malnourished and 80/99 (81%) had pulmonary TB only. The majority of the children (63/80, 79%) presented with cough of acute onset (<2 weeks). Only 5/36 (14%) eligible child contacts had documentation of receiving isoniazid preventive therapy. Twelve (13%) children had bacteriologically confirmed pulmonary TB. Overall, 93/97 (96%) children successfully continued TB care after hospital discharge. Favourable TB treatment outcomes were recorded in only 77 (78%) children. CONCLUSIONS: Children with TB managed at this district-level hospital were young, and frequently had acute symptoms and substantial comorbidities. Missed opportunities for TB prevention were identified. Linkage to care support resulted in excellent continuation of TB care; however, treatment outcomes could be further improved.https://www.ingentaconnect.com/content/iuatld/ijtld/2018/00000022/00000009/art00012Publisher's versio