Browsing Mechanical Engineering by Title
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Uziak, J.; Loukanov, I. A. (Dalhousie University, NaN, 2009)[more][less]
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Foster, J. D. G. (Tempus Publications http://www.ijee.ie/, NaN, 2002)[more][less]
Abstract: The economy of Botswana has grown rapidly since it became independent in 1966, but the population is only 1.7 million. Engineering construction projects are of large scale. The University of Botswana offers engineering degrees in four disciplines, under programs that cover ten semesters. The particular challenges to engineering education in Botswana, as well as the structure of the present and future University of Botswana programs, are described in this paper. Emphasis is placed on a wide range of student individual investigation and design work, and the benefits of a particular project to the student and the program are stated in an illustration. URI: http://hdl.handle.net/10311/704 Files in this item: 1
Uziak_IJEE_2002.pdf (769.0Kb) -
Uziak, J.; Foster, J.D.G. (University of Botswana, Faculty of Engineering and Technology, http://ajol.info/index.php/bjt, October NaN, 2001)[more][less]
Abstract: In this paper a method is presented which enables the solution of the equation of motion of the slider-crank mechanism. Expansion of functions into Fourier series is used in this method, whereby the solution of the equation of motion is also obtained in the form of Fourier series. This method enables also the determination of the coefficient of speed fluctuation of the slider-crank mechanism. The method creates the basis for an analysis of the influence of various factors, e.g. the working conditions or the construction parameters of the system, on the coefficient of speed fluctuation. URI: http://hdl.handle.net/10311/665 Files in this item: 1
Uziak_BJT_2001.pdf (2.257Mb) -
Uziak, J.; Foster, J.D.G. (University of Botswana, NaN, 2001)[more][less]
Abstract: In this paper a method is presented which enables the solution of the equation of motion of the slider-crank mechanism. Expansion of functions into Fourier series is used in this method, whereby the solution of the equation is also Fourier series. This method enables also the determination of the coefficient of speed fluctuation of the slider-crank mechanism. The methods create the basis for an analysis of the influence of various factors, e.g. the working conditions or the construction parameters of the system, on the coefficient of speed fluctuation. URI: http://hdl.handle.net/10311/702 Files in this item: 1
Uziak_BJT_2001.pdf (999.6Kb) -
Khartchenko, N.V.; Oladiran, M.T.; Douglass, G.W. (University of Botswana, http://www.ub.bw, NaN, 1999)[more][less]
Abstract: Coal is plentiful in many parts of the world but its combustion can create severe environmental and aesthetic problems.In the past three decades, the cost of crude oil and natural gas has been unstable and the reserves of these fuels are exhaustible. Other non-conventional energy resources, for example, solar, wind and tidal energy are only making a small contribution to the energy mix in few countries. Consequently, coal still has an important role to play to satisfy the energy demand, especially when it can be converted before combustion to other less environmentally objectionable forms, e.g. coal gas/producer gas. This paper describes the basic principles of coal gasification process and compares the performance of different gasifiers. The fundamentals of the raw gas cleaning methods are presented and experience to date of coal gasification in Botswana is discussed.It seems certain that coal gasification in tanderm with combined cycle power plant will be a principal technique for electricity generation in the next century. The paper recommends that Botswana takes necessary actions to gain maximum advantage from these developments. URI: http://hdl.handle.net/10311/710 Files in this item: 1
Khartchenko_BJT_1999.pdf (1.810Mb) -
Uziak, J.; Oladiran, M. T. (Tempus Publications http://www.ijee.ie/, NaN, 2009)[more][less]
Abstract: Complementary studies are fundamental for accreditation of engineering programmes in line with the Washington Accord. This paper presents the experiences of the University of Botswana in introducing General Education Courses (GECs) for the purpose of broadening the educational experience of all students, with particular reference to engineering students. Students registration data captured in the Integrated Tertiary Software (ITS) were analysed using Excel software. The five-year study period was from 2002 to 2007. Results indicate that engineering students mainly took GECs offered by the science and technology disciplines. It is concluded that GECs should be retained within the engineering programmes but the student advisory system should be improved and skills (e.g. IT competencies) that are important for professional development should be embedded in core courses instead of in general education. URI: http://hdl.handle.net/10311/700 Files in this item: 1
Uziak_IJEE2_2009.pdf (886.3Kb) -
Loukanov, I. A. (Research in Agricultural Engineering http://journals.uzpi.cz/web/RAE.htm, NaN, 2007)[more][less]
Abstract: This paper deals with the pumping process of a resonance-vibrating pump, which utilizes the resonance vibrations of one degree-of-freedom oscillating system. The pump is powered by a mechanical shaker consisting of two counter rotating offset masses and operating in resonance. The study investigates the nature of the pumping process and conditions required to achieve pumping action. Equations for the flow rate, pressure developed at ground level or any height above it, the pump efficiency, and the power delivered by the shaker are derived. The analysis of the pumping process revealed that the flow rate of the pump may be maximized either by increasing the acceleration imparted on the oscillating system, and/or by reducing the resonance frequency. It was found that the pressure developed by the pump is independent of the depth of pumping, provided that the same acceleration is imparted, and its efficiency may be increased either by reducing the resonance frequency and/or by increasing the depth of pumping. The preliminary test results about the flow rate and pressure developed at ground level appeared to be close to the values predicted by the proposed theory. Based on the analysis of the theoretical and experimental findings it is concluded that the equations derived in this study may be employed in designing resonance vibrating pumps for a desirable flow rate, pressure, and efficiency in pumping water from a specified depth. URI: http://hdl.handle.net/10311/693 Files in this item: 1
Loukanov_RAE_2007.pdf (792.9Kb) -
Ketlogetswe, C.; Kemoeng, L.L.; Nato, L.T. (University of Botswana, www.ub.bw, NaN, 2004)[more][less]
Abstract: This paper describes a case study that evaluated the level of recycling operations in Botswana. Recycling operations are now recommended as effective waste management strategies for reducing the amount of municipal solid waste disposed at landfill. In assesing the level of recycling operations in Botswana, two companies which are effectively involved in the recycling operation were selected as the focus of the evaluation process. Then data from the two companies is complemented by the data collected from Gaborone landfill site. Finally the role of non-governmental organisations particularly environmental watch Botswana (somarelang Tikologo) is discussed. URI: http://hdl.handle.net/10311/822 Files in this item: 1
Ketlogetswe_BJT-2004.pdf (799.8Kb) -
Ketlogetswe, C. (University of Botswana, NaN, 1998)[more][less]
Abstract: Since independence, the economy of Botswana has been undergoing a rapid transition from one in which the majority of the people depend on traditional agriculture and pastoralism to one in which formal sector employment predominates. This is partly reflected by rapid increase in vehicle population. Because of these changes,the country started to experience environmental problems. Unfortunately from the time of independence until late eighties, the level of environmental awareness in the country was very low, and therefore waste minimisation and reduction of environmental impact procedures were never in place.To date, many organizations in the country still seem not to be committed to reducing and disposing their wastes in environmentally friendly manner. The need to reconcile development with environmental concern, thus sustainable development, is vital. For the country to achieve that, an introduction of an environmental impact assessment in Botswana is essential, and thus, the main thrust of the current investigation is to determine the level of concern about environmental problems posed by waste engine oil in various organizations in the country. Management of various organizations were interviewed on their methods of waste of engine oil disposal. It was found that the disposal of waste engine oil by many organizations is resulting in serious environmental problems. URI: http://hdl.handle.net/10311/675 Files in this item: 1
Ketlogetswe_BJT_1998.pdf (1.028Mb) -
Ketlogetswe, C. (University of Botswana, Faculty of Engineering and Technology, http://ajol.info/index.php/bjt, April NaN, 1998)[more][less]
Abstract: Since independence, the economy of Botswana has been undergoing a rapid transition from one in which the majority of the people depend on traditional agriculture and pastoralism to one in which formal sector employment predominates. This is partly reflected by rapid increase in vehicle population. Because of these changes, the country started to experience environmental problems. Unfortunately from the time of independence until late eighties, the level of environmental awareness in the country was very low, and therefore waste minimisation and reduction of environmental impact procedures were never in place. To date, many organisations in the country still seem not to be committed to reducing and disposing their wastes in environmentally friendly manner. The need to reconcile development with environmental concern, thus sustainable development, is vital. For the country to achieve that, an introduction of environmental impact assessment in Botswana is essential, and thus, the main thrust of the current investigation is to determine the level of concern about environmental problems posed by waste engine oil in various organisations in the country. Management of various organisations were interviewed on their methods of waste engine oil disposal. It was found that the disposal of waste engine oil by many organizations is resulting in serious environmental problems. URI: http://hdl.handle.net/10311/659 Files in this item: 1
Ketlogetswe_BJT_1998.pdf (3.285Mb) -
Oladiran, M.T. (Elsevier Science Ltd, http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/description#description, NaN, 1995)[more][less]
Abstract: The use of solar energy is well established for low-grade thermal applications such as water heating and purification. In many of the solar systems, the collector surface located in the Northern Hemisphere faces the true south direction. However, there are occasions in which the radiation received by the collector at various orientations is desirable, such as a collector incorporated with a tracking system. The data for such situations are not available for several solar farms in Nigeria. Consequently, in this study, the average global radiation on flat surfaces was determined for three zones in Nigeria. The total insolation was obtained while the surface azimuth angle was varied between 0° and 75° at 15° intervals. The results are presented for three inclinations of the collector surface, namely L − 10, L, and L + 10 degrees respectively. URI: http://hdl.handle.net/10311/671 Files in this item: 1
Oladiran_AE_1995.pdf (1.847Mb) -
Foster, J.D.G.; Uziak, J.; Loukanov, I.A. (Blackwell Publishing Ltd, http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1475-1305, NaN, 2009)[more][less]
Abstract: This study presents the experimental setup and results of measurement of forces and moments in a manually operated ram press machine. Tests were conducted on a BP30 ram press using electrical resistance strain gauges to measure forces present in the machine under operating conditions. The forces were obtained by capturing data for the strains in six channels, using a digital instrument system, and later calculated by using the sensitivity factors. A method was proposed to estimate the tension force and bending moment in the connecting rods based on the sums and differences of measured strains. Results obtained were converted into spreadsheet data and presented in graphs versus the position angle of the operating lever. URI: http://hdl.handle.net/10311/633 Files in this item: 1
Foster_SIJEM_2009.pdf (460.1Kb) -
Marumo, R.; Tokhi, M.O. (University of Botswana, Faculty of Engineering and Technology, http://ajol.info/index.php/bjt, April NaN, 2007)[more][less]
Abstract: This article proposes a new modeling scheme using extended radial basis function (RBF) and adaptive neuro-fuzzy filter for handling nonlinear uncertainties of an air motor servo valve. This model combines the fast model development ability of RBF and the adaptation capability of adaptive neuro-fuzzy inference system (ANFIS) used instead of the well known conventional modeling techniques. The ANFIS structure provided parameter partitioning and better performance under transient response to handle the problem of disturbance attenuation. The pneumatic H-bridge, characterizing a pneumatic servo valve has been devised for speed and direction control of the motor and the system characteristics conveniently divided into three main regions; of low speed (below 390 rev/min), medium speed (390 to 540 rev/min) and high speed (540 to 680 rev/min). The system is highly non-linear in the low speed region and hence the need to use an adaptive intelligent based modeling technique arises. Simulation results has proven that for an air motor system with uncertainty and perturbed noise, the RBF-ANFIS model scheme performed well and out past its conventional counterpart by far. URI: http://hdl.handle.net/10311/657 Files in this item: 1
Marumo_BJT_2007.pdf (5.657Mb) -
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)