544 research outputs found

    Feature Trajectory Dynamic Time Warping for Clustering of Speech Segments

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    Dynamic time warping (DTW) can be used to compute the similarity between two sequences of generally differing length. We propose a modification to DTW that performs individual and independent pairwise alignment of feature trajectories. The modified technique, termed feature trajectory dynamic time warping (FTDTW), is applied as a similarity measure in the agglomerative hierarchical clustering of speech segments. Experiments using MFCC and PLP parametrisations extracted from TIMIT and from the Spoken Arabic Digit Dataset (SADD) show consistent and statistically significant improvements in the quality of the resulting clusters in terms of F-measure and normalised mutual information (NMI).Comment: 10 page

    Hierachical methods for large population speaker identification using telephone speech

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    This study focuses on speaker identificat ion. Several problems such as acoustic noise, channel noise, speaker variability, large population of known group of speakers wi thin the system and many others limit good SiD performance. The SiD system extracts speaker specific features from digitised speech signa] for accurate identification. These feature sets are clustered to form the speaker template known as a speaker model. As the number of speakers enrolling into the system gets larger, more models accumulate and the interspeaker confusion results. This study proposes the hierarchical methods which aim to split the large population of enrolled speakers into smaller groups of model databases for minimising interspeaker confusion

    Linguistics and HLT for Countries with Minimal ICT Infrastructure

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    Comparison of canine and premolar root lengths between group function and canine guided occlusions

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    A research report submitted to the Postgraduate committee in partial fulfilment of the requirements for the degree of Master of Dentistry in the branch of Orthodontics Parktown, Johannesburg, South Africa 2016Background: During orthodontic treatment, the maxillary canines are commonly extruded to give a patient canine disocclusion, without the clinician having previously checked as to whether the presenting function was canine guided occlusion or group function occlusion. There is a general belief that the roots of canines are longer than premolars and therefore are able to better withstand occlusal forces than the other teeth. Aim: The aim of this research was to compare the root lengths of the canines and premolars between and within subjects with canine guidance (CG) and group function (GF). Methods: Root lengths of canines and premolars were measured on periapical radiographs and compared between and within subjects with CG and GF. Results: The canine roots were generally longer than those of the premolars in both groups. However, this difference was much greater in the CG group compared with GF. Premolar roots in GF were significantly longer than in CG. Conclusion: Canine and premolar root lengths are fairly similar in GF but not in CG, where the canine roots are much longer than premolars. The roots of premolars in GF occlusion are longer than those in CG occlusion. There is no difference in root lengths of the canines between CG and GF occlusions.MT201

    Investigating the Effect of Surface Properties on Ice Scaling in Eutectic Freeze Crystallization

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    Eutectic Freeze Crystallization (EFC) is an innovative technology that can be applied to treat reverse osmosis (RO) waste streams (brines), to produce pure salt and water. Scaling of the heat exchanger (HX) surface by both ice and salt is currently one of the major drawbacks in the industrial implementation of EFC. At present scaling is controlled by the use of mechanical scraping, which is susceptible to mechanical breakdown, thus reducing the overall process efficiency. Previous studies have shown that lower surface energy materials delay the onset of freezing, and that smooth surfaces reduce nucleation and adhesion sites, thereby reducing the probability of scale formation. Therefore, this study aimed to investigate how the HX surface properties affect ice scaling in EFC, without the influence of mechanical scraping. Copper, Aluminium, Stainless Steel 316 and Brass were the selected HX materials. Ice scaling on the HX materials was investigated using a near eutectic 4 wt.% Na2SO4 aqueous solution, in a crystallization test cell uniquely designed to mimic the region near the HX wall of a crystallizer. The Differential Interference Contrast (DIC) technique was used to study the formation of the initial ice scale layer on the HX material used in the test cell. This method of observation was effective, asfor the first time in a continuous system, the crystallization of the initial ice scale layer was observable in-situ and in real-time. Therefore, with this method, it was possible to investigate the evolution of the predominantscaling modes(nucleation and growth), which differed for the different HX surfaces. The difference was proposed to be due to their distinct surface free energies and surface topographies. The effect of surface free energy and topography on the scaling induction time was investigated while operating at similar heat fluxes (similar cooling rates) for all the metals. The scaling induction time decreased with an increase in the surface free energy, with the Aluminium as an outlier. The recorded scaling induction times for Brass, primary-SS316 and Copper were 92.54, 70.95 and 54.06 min, respectively. Aluminium recorded the longestscaling induction time of 134.74 min. Both the polytetrafluoroethylene (PTFE) coated-SS316 and the primary-SS316 HX surface were used to investigate further the effect of surface free energy on the scaling induction time. The PTFE-coated-SS316 was found to increase the scaling induction times 2.79-fold at a coolant temperature of -15°C, compared to that of the primary-SS316. However, at -20°C and -25°C, the scaling induction times on both surfaces were comparable, which indicated that the benefit of using a low surface free energy material was limited by the cooling rate of the system. It was also found that the scaling induction times were shorter when using a rough-SS316 HX plate, compared to the primary-SS316, because of the larger surface area available for heat transfer. The end of the scaling induction time was characterised by the heterogeneous nucleation and subsequent growth of the ice on the HX surfaces. There was no direct correlation between the HX surface free energy and the nucleation and growth rates. This was because the Brass, Aluminium, SS316 and Copper plates all consist of different surface topographies which also influenced the nucleation and growth rates. However, the nucleation rates consistently increased when the scaling induction times were longer, regardless of the HX material used. The presence of deep sharp crevices on the primary-SS316 also enhanced nucleation rates. These deep sharp crevices created regions of high local supersaturation, where heterogenous nucleation predominated. It was, therefore, reasonable to conclude that the ice scaling induction time was increased by using smooth materials and those of lower surface free energy. The scaling mode was dependent on the surface topography and length of the ice scaling induction time, as longer ice scaling induction times resulted in heterogenous nucleation dominated scaling mode and vice versa. Materials that had a low surface free energy and were smooth minimised the nucleation rate, resulting in a reduced overall scaling rate

    Exploring the implementation of an internet based rehabilitation programme for HIV adults in a public health centre

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    Abstract South Africa has one of the largest population of adults living with HIV. About 30 to 60% of people living with HIV have been found to have HAND which can affect treatment with HAART which requires 95% compliance rate in order to be effective. Interventions that seek to alleviate the cognitive deterioration that is associated with HIV can include Internet based rehabilitation programmes. However, internet based interventions are plagued by poor adherence and attrition rates. The aim of the study was to describe the challenges and facilitating factors in the process of implementing the CogMed™ Working Memory Training Programme at a public HIV clinic for adults living with HIV. The study used a qualitative method with an ethnographic approach. Data was collected through CogMed™ administrator console, observations, interactions with gatekeepers, interactions and interviews with participants and interviews healthcare workers. The factors involved in the implementation process were categorised into the four “Stages of Use”. In the Recruitment/Consideration Stage perception of need, identifying and defining an ideal user were the main themes. Factors affecting the Initiation of Use Stage were sense of obligation, time to commit and access to suitable training environment. Utilisation of Service was influenced by ease of drop out, ease of use, perceived cost versus the perceived benefits of participating. Predisposing, enabling, and needs factors that affected adherence and participation were explored. Finally the Outcomes Stage covered the experiences and perceptions of using the rehabilitation tool. Limitations of the study were also discussed. Keywords: CogMed, Working Memory, HIV, HAND, Internet based interventions, Stages of Us

    Parallel Land Use and Land Development Application Procedures in a Semi-Urban Context: A Case Study of the Thembisile Hani Local Municipality

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    Planning Honours Report 2-15, Wits UniversityRural and former homeland areas, mostly within a semi-urban context, are predominantly characterised by parallel statutory and customary legislative regimes which are both fully recognised under the current constitutional dispensation of the Republic of South Africa. The existence of this dichotomy in rural South Africa pre-dates the 1996 Constitutional dispensation and is therefore the legacy of the apartheid era, which saw the passing of various laws such as the Bantu Homelands Constitution Act, 1971 (Act 21 of 1971) which was also later renamed the Self-Governing Territories Constitution Act, 1971 (Act 21 of 1971). The basis of the passing of these laws emanated from subsequent laws such as the Bantu Authorities Act, 1951 (Act68 of 1951) and the Promotion of Bantu Self-Government Act, 1959 (Act 46 of 1959) which also resulted in the establishment of tribal/traditional, territorial and regional authorities which relied on customary and indigenous understanding to the management of land.The statutory regulation of planning and land use management was later introduced in the self-governing and homeland areas with the promulgation of Proclamations R293 of 1962 and R188 of 1969 which were enacted as Land Use and Planning Regulations in terms of the Black Administration Act, 1927 (Act 38 of 1927). This signalled the beginning of a legacy of parallel land use and land development application procedures found in the semi-urban contexts of Post-Apartheid South Africa. The Post-1994planning legislative reform process has resulted in a planning system that is very complex and difficult for the rural communities to comprehend, and for the tribal/traditional authorities to embrace. The reason for the challenge induced on the rural community is due to the current planning laws that prescribe land use and land development application procedures that have very technical and expensive requirements for the majority of the rural community to understand and afford.On the other hand, discontent from the tribal/traditional authorities is due to the fact that the current institutional arrangements in terms of the Constitution of the Republic of South Africa, 1996 (Act 108 of 1996), the Local Government: Municipal Structures Act, 1998 (Act 117 of 1998), the Local Government: Municipal Systems Act & Regulations, 2000 (Act 32 of 2000), as well as the new Spatial Planning and Land Use Management Act, 2013 (Act 16 of 2013) has placed municipal Councils at Local Government, at the centre of planning and land use and development management decision-making, with tribal authorities as consulted participants in the process.In attaining the intended outcomes of planning, this therefore calls for an incremental approach to the introduction of a statutory land use management system, in as far as land use and development application procedures in a semi-urban context are concerned. This approach is one that embraces the incorporation of local indigenous and customary knowledge and understanding into land use planning and resource management. With the Thembisile Hani Local Municiplality as a case study, emphasis is placed on the context-specificity of land use management systems and applicable procedures in a semi-urban context

    University of the Witwatersrand residence students' perspectives on factors that promote or hinder academic success

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    Academic attrition remains a phenomenon that riddles educational institutions world-wide. This study sought to explore perceptions of residential students on the matter; to engage them in ascertaining how they have managed to pursue their studies as well as perhaps find out what challenges the students faced which that could lead to attrition. Correlational and phenomenological research designs were used. The correlational research design was used in determining the relationship between variables measured through the study instruments. The phenomenological research design was used to explore students’ views on how they had experienced academic success thus far. This study was conducted with residential students from the University of the Witwatersrand. A total of sixty-six participants participated in this study and their ages ranged from nineteen to thirty-eight years
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