Browsing Mechanical Engineering by Title
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Now showing items 26-39 of 39
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Masoso, O.T. (Elsevier http://www.linkinghub.elsevier.com/retrieve/pii/S0378778808000923, NaN, 2008)[more][less]
Abstract: This paper presents the findings of a case study with building simulation using EnergyPlus dynamic thermal simulation software, in which wall insulation was varied together with cooling set-point temperature in a hot and dry climate of Botswana. Against the established norm that adding wall insulation reduces annual fuel consumption, it is shown in this paper that this is not always the case: there are instances where adding wall insulation directly increases annual fuel consumption. Initial cost of insulation aside, as the cooling set-point temperature is gradually increased, the building switches from an ‘‘insulation reduces cooling load’’ to an ‘‘insulation increases cooling load’’ behaviour. In other words, the well established knowledge that ‘‘the lower the u-value the better’’ gets overridden by ‘‘the higher the u-value the better’’. We termed this a ‘‘point of thermal inflexion’’. Simple graphical demonstration of the existence of this point is presented in the paper. According to the findings, design engineers and building economics related professionals who quantify investment on insulation can get disastrous results if they assume that all buildings behave pro-insulation since a building may behave anti-insulation. URI: http://hdl.handle.net/10311/673 Files in this item: 1
Masoso_EB_2008.pdf (867.2Kb) -
Inambao, F.L.; Mosweu, M. (University of Botswana, NaN, 2001)[more][less]
Abstract: Diesel engines are used in heavy duty applications because of their high effeciency an reliability. However, oxides of nitrogen emissions remain a major concern. In diesel engines, fuel combustion is responsible for a major proportion of oxides of nitrogen emissions. Four sources of the oxides have been identified. The range of possible types of damage to environment and health, as well as effective methods for reduction of oxides of nitrogen, have been analysed. URI: http://hdl.handle.net/10311/620 Files in this item: 1
Inambao_BJT_2001.pdf (1.720Mb) -
Uziak, J.; Loukanov, I. A. (CIGR Journal http://www.cigrjournal.org/, NaN, 2007)[more][less]
Abstract: The ram-press technology for oil expression has received a lot of attention in many African countries during the last two decades. The technology is based on manually operated mechanical presses, which employ a slider-crank mechanism in two different configurations. The original machine was invented by Karl Bielenberg in 1985 and since then continuous design improvements have been made to improve their performance and ease of operation. This paper deals with the performance of some commonly used ram press machines such as BP-35, BP-30 and FI-32, in order to establish their suitability for small rural oil expression technology. The available oil-seed processing techniques were discussed, including their suitability for locally grown sunflower varieties, and the characteristics of the ram press machines. The machines were tested by using three varieties of sunflower seeds, namely PNR 7225, PNR 7369, and Peredovik. The machines were compared by their outputs obtained when conducting a high production and high expression tests. Based on the above analysis the Camartec design (BP-30) was found to have the best performance. The machine had the highest efficiency and also the highest expression rate in comparison to CAPU design (BP-35) and RAM design (FI-32) machines. The FI-32 machine was found to be ineffective, having in the high expression test an expression rate below 20% irrespective of the type of seeds used. In terms of the speed of oil production the CAPU (BP-35) design performed better then the other machines. However in the high production test its performance was similar to that of Camartec machine. URI: http://hdl.handle.net/10311/697 Files in this item: 1
Uziak_AEI2_2007.pdf (989.2Kb) -
Mothibi, J.; Kutua, S. (University of Botswana, www.ub.bw, NaN, 2001)[more][less]
Abstract: One of the critical elements that determine the competitiveness of nations is the population density of, and quality of its engineers. This view has been corroborated by researchers such as Biluch (1989), Garelli et al (1997), and Gharajedaghi (1986). Unfortunately most African countries are not performing well on this front. Engineering education institutions, entrusted with the task of improving the measures, find themselves in the uneviable position of attempting to operate in environments in which governments are continuously reducing funding to education in general. The objective of this paper is to develop conceptual models which can aid engineering institution overcome the financial constraints, increase throughput of engineers, and improve the quality of engineering education. The model is based on the cybernetics paradigm and is validated through structural and multiplicative corroboration. URI: http://hdl.handle.net/10311/825 Files in this item: 1
Mothibi_BJT_2001.pdf (725.3Kb) -
Mothibi, J.; Kutua, S. (University of Botswana, Faculty of Engineering and Technology, http://ajol.info/index.php/bjt, October NaN, 2001)[more][less]
Abstract: One of the critical elements that determine the competitiveness of nations is the population density of, and quality of, its engineers. This view has been corroborated by researchers such as Bilich (1989), Garelli et al (1997), and Gharajedaghi (1986). Unfortunately, most African countries are not performing well on this front. Engineering education institutions, entrusted with the task of improving these measures, find themselves in the unenviable position of attempting to operate in environments in which governments are continuously reducing funding to education in general. The objective of this paper is to develop a conceptual model which can aid engineering institutions overcome the financial constraints, increase throughput of engineers, and improve the quality of engineering education. The model is based on the cybernetics paradigm and is validated through structural and multiplicative corroboration. URI: http://hdl.handle.net/10311/663 Files in this item: 1
Mothibi_BJT_2001.pdf (3.126Mb) -
Kiravu, C.S.A.M. (University of Botswana, NaN, 2000)[more][less]
Abstract: Computer models are used to replicate the essential performance features of a physical element using convenient modeling and simulation programs. Within SPICE, an acronym for the Simulation Program with Integrated-Circuit Emphasis, a model for the twin-depencence of the machine's open circuit generated e.m.f. on the time-independent flux and machine speed has not been investigated. This paper describes a steady state model of an open circuit DC shunt machine using PSPICE, the PC version of SPICE packaged within the OrCAD programming environment. The model is based on characterization of the generated e.m.f.as field current dependent polymial voltage source whose coeffecients are generated within MATHCAD by applying a linear regression fit on a set of experimental laboratory data points. The simulation results are displayed using the inbuilt graphic postprocessor within PSPICE called PROBE. This results show good replicative model validity within the laboratory range of exciting currents used in the simulative. URI: http://hdl.handle.net/10311/621 Files in this item: 1
Kiravu_BJT_2000.pdf (849.3Kb) -
Matshediso, I.B. (University of Botswana, http://www.ub.bw, NaN, 2004)[more][less]
Abstract: Although most SADC countries have or were in the process of liberalizing their legislation and fiscal regimes some member states seemed to levy exorbitant tax rates. SADC members’ states need to note that in designing the optimum tax regime for their respective countries a balance will have to be struck between all the role-players including the investor, government and the community. It is imperative that the tax regimes are designed to provide stability over time and are transparent, easy to administer and internationally competitive. Mining investors view taxation systems as a cost of doing business in a particular country. The effects of taxes can influence company decisions. It is therefore of paramount importance for SADC governments to design tax regimes which will allow the mining sector to get a return on investments which is commensurate with the capital outlay and risk. It is equally important that the mining business should play a key role to the socio-economic developments of the host country in terms of job markets, secondary industries, hospital, schools, skills development and education. The taxation level in SADC countries should be both comparable and competitive with other countries with similar geological potential and this is currently not the case. Chile offered investors the best fiscal regime when compared to the twelve selected SADC countries. URI: http://hdl.handle.net/10311/1107 Files in this item: 1
Matshediso_BJT_2004.pdf (1.076Mb) -
Ketlogetswe, C.; Fiszdon, J.K.; Seabe, O.O. (Elsevier Science Ltd. www.elsevier.com/locate/rser, NaN, 2007)[more][less]
Abstract: Import of a huge proportion of electrical energy from the Southern African Power Pool, and the geographical location and population distribution of Botswana stimulated the need to consider renewable energy as an alternative to imported power. The paper describes a systematic experimental study on a mini-solar chimney system. Particular attention is given to measurements of air velocity, temperature and solar radiation. The results for the selected 5 and 6 clear days of October and November, respectively, are presented. These results enable the relationship between average insolation, temperature difference and velocity for selected clear days to be discussed. URI: http://hdl.handle.net/10311/271 Files in this item: 1
Ketlogetswe_RSER12_2008.pdf (1.195Mb) -
Ketlogetswe, C.; Mothudi, T.H. (Elsevier Science Ltd. http://www.elsevier.com/locate/rser, NaN, 2009)[more][less]
Abstract: Lack of access to electricity grid form the main challenge facing majority of developing regions particularly in rural communities. The situation is driven mostly by the absence of electricity infrastructure in most of the developing countries particularly in rural communities. A number of developing countries are now encouraging the use of solar home systems in isolated areas. Botswana is not immune to this trend. Consequently, available evidence puts the overall contribution of solar energy to primary energy supply in Botswana to less than 1%. A plethora of factors are responsible for inhibiting rapid development of solar home systems in isolated areas in Botswana. Some major impediments often cited as causing low use of solar home systems by rural communities in Botswana include, among others, the following: (i) Low-income status of most rural inhabitants. (ii) Migration of house-owners from village status to lands, or cattle posts. This paper, therefore, analyses factors that impede the rapid development of photovoltaics power generation systems in rural environments in Botswana. The analysis is based on photovoltaic power generation pilot project which was carried out in three (3) villages in Botswana, namely Kudumatse, Lorolwana and Motlhabaneng. URI: http://hdl.handle.net/10311/327 Files in this item: 1
Ketlogetswe_RSER_2009.pdf (1.107Mb) -
Oladiran, M.T.; Pheko, H. (Elsevier Science Ltd, http://journals.elsevier.com/00014575/accident-analysis-and-prevention/, NaN, 1995)[more][less]
Abstract: In many African countries, including Botswana, the driving schools and instruction given to pupils are uncontrolled. Thus, this paper presents the results of an investigation into the level of professional training offered by the driving schools in Gaborone. A total of 400 randomly selected drivers completed questionnaires on their training, accident records, and L-tests. Male trainee drivers received more instruction than females, and there was some indication that the pass rate on L-tests was lower for female drivers. Also, the pickup van forms the majority of the national vehicle population. It accounts for almost 40% of the accidents but is presently not used for training in the commercial driving schools. It is concluded that the quality of professional instruction in driving schools needs improvement so that learners can be encouraged to take training from these institutes. URI: http://hdl.handle.net/10311/669 Files in this item: 1
Oladiran_AAP_1995.pdf (1.673Mb) -
Kanyarusoke, K.E.; Uziak, J. (Wiley Periodicals Inc. http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-0542, NaN, 2009)[more][less]
Abstract: Formal Engineering Education has traditionally been delivered using the low technology—high touch lecturing method, in which the lecturer and student meet face to face. Distance education in this field has been quite slow to develop primarily because of difficulty in delivery of practical based instructions and problems on integrity of assessments. Developments in information technology and the increased demand for further education by people already in employment have however changed this even in developing countries. It puts extra demand on Lecturers to guide distance learners in handling numerical computations so prevalent in Engineering. At the campuses, computer based methods are available in the high touch—high tech lecture method. High level and efficient computer software is used to help the student to simulate and solve some problems. However, such software is expensive—and therefore—not readily available to the distant learner. Spreadsheets on the other hand are almost universal on today’s computers and they bridge the gap between hand calculations and high level programme computations. This paper therefore makes a case for the use of spreadsheets in Distance Engineering Education. An example in Spring Design, Selection and Adaptation is used to illustrate the simplification and other advantages of their use by practicing distance learners. URI: http://hdl.handle.net/10311/603 Files in this item: 1
Kanyarusoke_CAEE_2009.pdf (1.031Mb) -
Loukanov, I. A.; Uziak, J. (International Symposium on Theory of Machines and Mechanisms (IFToMM), NaN, 2001)[more][less]
Abstract: The single-stroke ram press machine is widely used for sunflower oil extraction in African countries. It is manually operated, low speed machine constructed on the basis of slider-crank mechanism. The paper presents a detailed theoritical analysis of the mechanism of the linkage system. The analysis is done for different positions of the driving lever (handle) nad other parameters, which influence the performance of the machine. Based on that analysis conclusions on the optimal performance of the mechanism are drawn. URI: http://hdl.handle.net/10311/667 Files in this item: 1
Loukanov_IFToMM_2001.pdf (993.1Kb) -
Oladiran, M.T. (Elsevier Science Ltd, http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/description#description, NaN, 1994)[more][less]
Abstract: Solar energy is finding wide application via several energy-saving devices and systems. Its use, especially in rural areas, can often be limited by the non-availability of complete information on insolation data. In this investigation, both the mean extraterrestrial and terrestrial radiations were calculated for three zones in Nigeria. These zones were assumed to be dependent mainly on the latitude, L. The isotropic model was employed for the computation of the diffuse and ground reflected components of radiation. Consequently, the total insolation was obtained for various inclinations of the collector surface. It was found that three solar energy seasons exist for each zone. For maximum total incident radiation, a different collector inclination is ideal for each solar energy season. However, for all year round applications, a fixed inclination varying between L and (L+10) degrees is recommended. URI: http://hdl.handle.net/10311/672 Files in this item: 1
Oladiran_AE_1994.pdf (1.391Mb) -
Kutua, S.; Mothibi, J. (University of Botswana, Faculty of Engineering and Technology, http://ajol.info/index.php/bjt, April NaN, 2003)[more][less]
Abstract: “Sustainable development” as a concept was popularised by a 1987 report of the United Nations World Commission on Environment and Development. The report defined sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. However, from this definition, we cannot ascertain the central intuition of the notion of sustainable development. Failure to do this makes it difficult to derive methods that can be used to formulate effective intervention policies that can enable nations to attain sustainable development. This paper briefly reviews various schools of thought in popular literature on the notion of sustainable development, exposes their weaknesses and develops a holistic notion of sustainable development based on the systems approach. URI: http://hdl.handle.net/10311/660 Files in this item: 1
Kutua_BJT_2003.pdf (5.513Mb)
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Now showing items 26-39 of 39