A study of the charge structure and energy utilisation in a Stirred Media Detritor using DEM-SPH

The Stirred Media Detritor, (SMD), is a grinding device used for fine and ultra-fine grinding applications in mineral processing. The SMD has a vertically orientated shell that supports a shaft, with protruding impeller arms for agitating the charge. There is currently limited understanding of charge structure and motion in the SMD, particularly the interaction of the media and the slurry. Additionally, the number of arms and their arrangement on the shaft, are important aspects of the impeller that determine flow, energy consumption and grinding efficiency. Impeller geometry choices affect these characteristics of the process. This work focuses on studying the flow of grinding media and slurry for the industrial scale SMD 1100- E. This information is used to explore charge dynamics and energy utilisation in the SMD. To investigate the effect of impeller arm configuration on the operational behaviour of the SMD, the commercially available impeller configuration of the industrial scale SMD 335-E is used as the base case. Mill charge dynamics, transport and mixing, patterns of energy absorption on the mill surfaces are examined for the base case and compared to three different impeller arm arrangements. A two-way transient coupled Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics model is used to achieve this. The ceramic grinding media is represented by the DEM component of the model, which is fully resolved, while the slurry (water and fine particles) is represented by the Smoothed Particle Hydrodynamics (SPH) model. The focus is on steady state operation therefore discharge from and feed into the mill are omitted. A nominal media size of 8 mm is used. The rotational action of the impeller forces the charge to the mill wall creating vortex centred on the mill shaft. The vortex is conical with a large diameter at the bottom, which decrease towards the bottom of the mill. Abrasion is found to be the dominant breakage mechanism in the SMD. Mixing behaviour is complex with media transfer past layers of impeller arms being influenced by the fall distance of media between impeller arm encounters

African languages as medium of assessment in the teaching of indigenous languages in higher education: a paradigm shift

This study was a call for a paradigm shift in the language of assessment for indigenous languages in higher education. It challenged the continued use of English in Teaching Practice supervision at one Zimbabwean State University whose language policy emphasises the teaching of African languages through the respective languages. It sought to establish challenges encountered by students studying African languages who are taught and examined through indigenous languages in all the other modules except for Teaching Practice. This research used the qualitative paradigm where ten randomly selected student teachers practicing ChiShona were interviewed together with two section coordinators. Document analysis was also used to analyse assessment reports. From the study, it was established that the English instruments were designed to accommodate supervisors who are not indigenous languages specialists, there was confusion among supervisors and supervisees on translating indigenous languages on documents and used during lesson delivery to English and vice versa and the student teachers’ potentials were limited due to difficulties in interpreting the instrument. The study concluded that the use of English in teaching practice for African languages was not effective as it compromised quality in both practice and supervision. It, therefore, recommends the use of assessment instruments prepared in indigenous languages

Hospitality Industry Law 11

Exam paper for first semeste

The South African Shipping Industry: BEE and Seaborne Trade.

Thesis (MBA)-University of KwaZulu-Natal, 2006.The South African Maritime Industry has, as well as other industry sectors, recently been exposed to the dynamics that have been brought about by the Broad Based Black Economic Empowerment Policy which has become law in South Africa. The nature of the policy has created a situation where it (the policy itself) needs to have attention apportioned to it. The attention has been directed towards the implementation of the policy by the shipping companies. In addition, there has been attention directed towards compliance with the legislation that polices Broad Based Black Economic Empowerment. The government's requirement that the South African maritime industry generates a strategy document led to the adoption, by the industry's major role players, of the Maritime Transport & Service Industry Black Economic Empowerment Charter. The purpose of this research work is to investigate and create an understanding whether the aspirations of the above mentioned charter are realistic and feasible to achieve when, the nature of the shipping industry and other maritime related businesses, is considered. Does the way in which the shipping business operates make it easy for Broad Based Black Economic Empowerment to be implemented in the way proposed by the charter? The qualitative theory generating approach is adopted on the research. In the design of this research work a case. study is done where a major shipping company, Island View Shipping was studied. The aim is to consider issues that affect the maritime industry as viewed from inside the business environment. Semi-structured interviews are also conducted with the individuals at Island View Shipping who have, for many years, played (working in different levels/positions and working for different companies almost all over the world) major roles in the company itself and in the industry in general. Data analysis is based on the inductive reasoning approach where themes are created and analyzed. The conclusions and recommendations are divided according to themes that are identified in Chapter Five

A política dos livros didáticos de história nas salas de aula sul-africanas na era do Curriculum 2005

A África do Sul celebrou recentemente vinte anos da transição política do regime de apartheid para uma nação democrática. Uma das mudanças importantes nesta transição foi a reforma curricular, incluindo a natureza do conteúdo dos livros didáticos ensinado nas escolas Sul-Africanas pós-apartheid. Este artigo discute o conteúdo dos livros didáticos na era do Curriculum 2005, uma declaração nacional curricular introduzida em 1997 e posteriormente revista em 2002. Primeiramente, discuto a história sócio-política da educação na África do Sul, incluindo a transição do apartheid para o pós-apartheid como um contexto para esta análise. Em segundo lugar, descrevo as limitações de conteúdo dos livros didáticos de história, ensinado nas salas de aula pós-apartheid. Usando a teoria crítica, argumento que o conteúdo dos livros adotados recentemente não interrompeu de forma decisiva a histórica deturpação e sub-representação da história política de grupos marginalizados na África do Sul, embora alguns livros tenham feito mais progressos do que outros.Palavras-chave: Livros Didáticos de História. África do Sul. Pós-Apartheid. Curriculum 2005. Teoria Crítica

Ideal hydrocracking catalysts for the conversion of FT wax to diesel

Includes bibliographical references.The Fischer-Tropsch wax synthesis process and the subsequent upgrade of the wax to useful distillate fuels by mild hydrocracking is a well-known, economically viable method of producing liquid fuels, in particular diesel fuel. This project seeks to develop an ideal hydrocracking catalyst (i.e. a hydrocracking unit in which only primary cracking occurs) for the conversion of Fischer-Tropsch (FT) wax to diesel and to determine the effect of carbon monoxide on the activity and selectivity of the hydrocracking catalyst for possible integration of low temperature FT wax synthesis with wax hydrocracking into a single stage. Theoretically, a combination of the Fischer-Tropsch unit with an ideal hydrocracking unit can produce diesel yields of up to 80 wt. A non-ideal hydrocracking catalyst would lower the middle distillate yields due to the occurrence of secondary cracking. Primary cracking of the paraffins produced by the low temperature FT process occurs only when the activity of the metal is high and the rate limiting step occurs on the acid site. Integrating the wax synthesis process with the subsequent work up of the wax to produce distillate fuels is not without challenges, mainly the low reaction temperature and pressure (225°C and 20 bar), in which the hydrocracking catalyst is to operate. Noble metals, combined with zeolites are known to be active for hydrocracking at such conditions. Carbon monoxide, a feedstock of the FT process poisons noble metal catalysts; therefore knowledge of its effect on the hydrocracking catalysts performance is essential. The hydrocracking catalysts were tested when the metal and the acid sites were segregated (i.e. the metal supported on an inert carrier, physically mixed with the zeolite), and when the two sites are in close proximity (i.e. the metal impregnated into the zeolite). The tests were carried out both in the presence and absence of CO consistent with the FT feed ratio. The noble metals, Rh, Ru and Pd were used as co-catalysts to H-MFI-90. It was found that the physical distance between the metal and the acid sites has disturbs the balance of the two sites by introduction of a transport steps, this seen through both the activity and selectivity of the catalyst. Pd exhibited higher activity than Rh and Ru. Primary cracking was found to be unattainable when the metal and the acid sites are segregated. When the metal and the acid sites were in close proximity (impregnated catalyst), near primary hydrocracking performance was observed at metal loading of 0.9 wt Pd. Secondary cracking was aggravated upon the introduction of CO on both the segregated and impregnated catalyst

Introducing portfolio assessment as an alternative assessment method in the Department of Biomedical Technology at Mangosuthu Technikon : the perceptions of staff and students.

Thesis (M.Ed.) - University of KwaZulu-Natal, Pietermaritzburg, 2008.The assessment procedures utilized in the Department of Biomedical Technology at Mangosuthu Technikon were critically reviewed. This revealed a rather narrow approach with an emphasis on traditional assessment methods such as tests and examinations that provide limited feedback that does not necessarily determine whether learning has taken place. This study was prompted by the realization that the existing traditional methods of assessment promote or encourage a surface approach to learning which makes it difficult for the students to transfer the theoretical knowledge that they have attained into the practical performance that is required in the workplace. The study was conducted over a period of four years using an action research approach, which revolved mainly around the use of the existing assessment methods and an evaluation of the participants’ perceptions regarding the introduction of portfolio assessment in the Department of Biomedical Technology at Mangosuthu Technikon. During the study a group of students in the Department of Chemical Pathology was exposed to an in-course portfolio assessment as well as an experiential training portfolio assessment. A number of variables in the in-course portfolio assessment was tested. These variables were related to the concerns raised in the workplace. The introduction of the in-course portfolio showed some improvement in the way students performed their basic duties in 2005. The 2006 group of students was not exposed to the in-course portfolio assessment therefore this provided a better comparison of students by the employers. The study also involved the lecturers in the department who had different opinions regarding portfolio assessment. It was found that some of them supported the idea whereas others felt that the time allocated for lecturers’ duties did not permit them to introduce such a time-consuming assessment format. Employers involved in the study clearly indicated which areas or skills students needed to develop before they could come to the workplace for experiential training. However, the researcher concluded that some of those skills could be accumulated with further years of work experience. The study revealed that a significant portion of the students realized that, by integrating assessment in the learning process, they are able to be more critical of their own work, thereby putting more effort into understanding what they learn through the use of formative assessment. This in turn should pave the way for students to understand that learning is no longer teacher-centred, but learner-centred. This approach means that they are expected to work in more reflective and independent ways in the future. The study highlighted a number of issues that need to be addressed in assessment strategies. The lecturers were accustomed to assessment system that was time-efficient and yielded the scores required by the system. However, the way this assessment system related to learning was not so clear to either lecturers or students. Particularly, students felt that a mark did not necessarily reflect what they knew about the subject matter. They argued that if the same subject content had been assessed in other ways, a different performance outcome might have been achieved. This means that the actual awarding of marks is an intimidating process for some students and that ways should be found to render assessment less intimidating or threatening. A critical finding of the study is that assessment requires not only a high level of critical reflection, but also active engagement and discipline-specific knowledge by the lecturers to make the necessary changes for an assessment method where students’ learning is the centre of focus

The Phenomenon of church hopping in the Black community of Rustenburg : an investigation into some underlying factors

Introduction: Rustenburg is a fast growing city in the world. This growth influences establishment of new faith based churches which is, in many respects at the expense of mission churches. The HIV/AIDS pandemic and diseases related to stresses results in movement of Christians from one church to the other. Christians are vulnerable when facing life stressors which results into changing allegiance to a particular church. This is a qualitative descriptive/ exploratory study Method: The researcher purposely selected respondents from the black Christian community of Rustenburg. These are those Christians who have moved from one church to join another .From these interviews the themes that emanate are discussed. Leaders of prominent churches were also interviewed . Findings: The qualities of church leaders have an influence on the movement of its members. The media, especially the local radio station has been widely used to attract new members. The availability of a pastor in times of need plays a vital role. Power struggles seem to disappoint some loyal Christians who may reluctantly leave the church. Financial benefits also play an important role in attracting membership. The faith based churches have grown both in numbers and in membership. Women with their healing power are active especially in the Zion churches. The help seeking behaviour of Christians also influences their affiliation to a particular church such as seekingChristian Spirituality, Church History and MissiologyM. Th. (Missiology