Browsing Mechanical Engineering by Issue Date
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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) -
Loukanov, I. A.; Uziak, J.; Michalek, J. (Czech Academy of Agricultural Sciences http://agriculturejournals.cz/web/RAE.htm, NaN, 2005)[more][less]
Abstract: The power requirement of tillage implements is an important design consideration particularly for animal-drawn implements where the power is limited. The paper presents the possibility of reduction in the draught requirements of animal-drawn mouldboard plough by using enamel coating on the soil-engaged components such as the mouldboard, share and the landside. Trials were conducted to compare enamel-coated Maun Series single mouldboard plough (manufactured by Zimplow Limited, Bulawayo, Zimbabwe) with similar uncoated plough, both animal-drawn, under comparable working conditions. Experiments were done at 25% and 32% d.b. soil moisture content on a red clay soil in Zimbabwe. The parameters measured in evaluating the draught performance of both ploughs were the tractive effort(pull),speed of ploughing,depth and width of ploughing,and soil conditions(i.e.soil moisture content,soil bulk density and soil penetration resistance). It was found that for similar working conditions the enamel coating reduced the specific draught by 20 to 26% depending upon soil moisture content. URI: http://hdl.handle.net/10311/705 Files in this item: 1
Uziak_RAE_2005.pdf (504.4Kb) -
Oladiran, M.T.; Meyer, J.P. (Elsevier http://www.elsevier.com, NaN, 2007)[more][less]
Abstract: The energy-utilization over a 10-year period (1994–2003) has been analysed for the South African industrial sector, which consumes more primary energy than any other sector of the economy. Four principal sub-sectors, namely iron and steel, chemical and petrochemical, mining and quarrying, and non-ferrous metals/non-metallic minerals were considered in this study. Primary-energy utilization data were used to calculate the weighted mean energy and exergy efficiencies for the sub-sectors and then overall values for the industrial sector were obtained. The results indicate that exergy efficiency is considerably lower than energy efficiency in all the sub-sectors, particularly in mining and quarrying processes, for which the values were approximately 83% and 16%, respectively. The performance of exergy utilization in the industrial sector can be improved by introducing various conservation strategies. Results from this study were compared with those for other countries. URI: http://hdl.handle.net/10311/957 Files in this item: 1
Oladiran_AP_2007.pdf (792.0Kb) -
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) -
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) -
Loukanov, I.A.; Uziak, J. (Akademiai Kiado, NaN, 2007)[more][less]
Abstract: The effect of enamel-coating on the draught performance of an animal-drawn mouldboard plough was studied. A single furrow swing mouldboard plough-Maun Series, and the same type enamel-coated plough both ox-drawn, are compared under similar working conditions such as soil moisture content, depth and width of cut and approximately constant speed of ploughing. It was found that the enamel-coating reduces both the plough draught and the specific draught. The percentage reduction of the plough draught for enamel-coated plough compared to uncoated plough varied from 12.7% at 25% soil moisture content to 18.1% at 32% soil moisture content (dry basis). It was also found that the percentage reduction of the specific draught achieved with the enamel-coated plough in comparison with the uncoated plough varied from 20.3% at 32% soil moisture content to 25.7% at 25% soil moisture content (dry basis). URI: http://hdl.handle.net/10311/632 Files in this item: 1
Loukanov_PAES_2007.pdf (692.2Kb) -
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) -
Meyer, J.P. (Elsevier Science Ltd, http://www.elsevier.com/locate/apenergy, NaN, 2007)[more][less]
Abstract: The energy-utilization over a 10-year period (1994–2003) has been analysed for the South African industrial sector, which consumes more primary energy than any other sector of the economy. Four principal sub-sectors, namely iron and steel, chemical and petrochemical, mining and quarrying, and non-ferrous metals/non-metallic minerals were considered in this study. Primary-energy utilization data were used to calculate the weighted mean energy and exergy efficiencies for the sub-sectors and then overall values for the industrial sector were obtained. The results indicate that exergy efficiency is considerably lower than energy efficiency in all the sub-sectors, particularly in mining and quarrying processes, for which the values were approximately 83% and 16%, respectively. The performance of exergy utilization in the industrial sector can be improved by introducing various conservation strategies. Results from this study were compared with those for other countries. URI: http://hdl.handle.net/10311/668 Files in this item: 1
Oladiran_AE_2007.pdf (589.3Kb) -
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) -
Uziak, J.; Loukanov, I. A. (Dalhousie University, NaN, 2009)[more][less]
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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) -
Oladiran, M.T.; Foster, J. (Trans Tech Publications http://www.scientific.net/AMR.62-64.551, NaN, 2009)[more][less]
Abstract: A team of academics produced a Design Brief (DB) to assist architects design a scholarly physical environment for modern engineering education and research. The information gathered from external and internal sources was used to define important themes that the buildings should reflect and hence to arrive at a list of the required spaces. Critical internal and external reviews and budget constraints led to a series of successive refinements of the DB. A design competition was organised for all interested architects in the country to select the architect for the project and consolation prizes were awarded to second and third finalists. The planned development will provide 17900 m2 and 25200 m2 net usable space and estimated gross building area respectively. URI: http://hdl.handle.net/10311/599 Files in this item: 1
Oladiran_AMR_2009.pdf (635.7Kb) -
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) -
Uziak, J.; Gizejowski, M. (University of Botswana, NaN, 2009)[more][less]
Abstract: A new design developed by the authors that gives an opportunity to account for the interaction of different modes of buckling is presented.Eurocode 3 model is used as the reference model, an equivalent geometric imperfection comprising of an initial bow being equal to the length divided by 500 is used.The model is based on the design criterion referred to the individual chord components. It allows to avoid the application of complicated procedure based on an explicitly given imperfection parameter. It is achieved by a treatment of a chord local buckling mode between lacing connections in the same way as the plate buckling of chord sectional elements.The buckling design of the compound number can therefore be carried out in the same wayas for a single element provided that the stiffness of lacing members is properly taken care of. URI: http://hdl.handle.net/10311/610 Files in this item: 1
Uziak_BJT_2009.pdf (1.086Mb) -
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) -
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) -
Acceptance of blackboard technology by mechanical engineering students at the University of BotswanaUziak, J. (Tempus Publications, NaN, 2009)[more][less]
Abstract: Technology-based teaching and learning is entering academic life at an amazing rate. It comes whether invited or not. Students and lecturers are confronted with new technologies. There are new teaching methods to accompany them, and new pressures to use them. E-learning is penetrating all areas of teaching and learning: academic institutions and corporate training alike. It has been generally accepted as a major and viable component of higher education. However, it is not clear how students accept the use of new technology. This paper deals with the question of acceptance by analysing the University of Botswana engineering students' reflection on Blackboard technology. URI: http://hdl.handle.net/10311/694 Files in this item: 1
Uziak_IJEE_2009.pdf (976.8Kb) -
Batane, N.R.; Morrison, D.J.; Moosbrugger, J.C. (Elsevier, www.elsevier.com, NaN, 2010)[more][less]
Abstract: The axial–torsional cyclic deformation behavior of polycrystalline nickel was investigated by performing fully reversed plastic strain amplitude controlled fatigue experiments at effective plastic strain amplitudes ranging from 1×10−4 to 1×10−3. Experiments were accomplished under proportional and 90◦ out-of-phase nonproportional loading paths. Results indicate that loading path has very little effect on the cyclic response at the lower effective plastic strain amplitude. However, at the higher effective plastic strain amplitude, significant additional hardening is induced by the nonproportional loading path. Description: some symbols may not appear as in the original abstract. URI: http://hdl.handle.net/10311/847 Files in this item: 1
Batane_MSE_2010.pdf (613.9Kb)
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