http://ir.bdu.edu.et/handle/123456789/10157 There are three undergraduate and five postgraduate programs running under the Faculty of Mechanical and Industrial Engineering..The mechanical engineering program is a full time based on-campus mode program offered during the day time via lecture, tutorial, and laboratory. Aside the traditional way of course delivery students will take a one semester intensive internship at different factories at a national level. Sat, 13 Jan 2001 06:34:47 GMT 2001-01-13T06:34:47Z http://ir.bdu.edu.et/handle/123456789/16591 DESIGN AND PERFORMANCE INVESTIGATION ON ROUGHENED SOLAR-ABSORBER DRYER Urmale, Wegaso Kambo Solar air heaters have been used for many purposes requiring low to medium grade thermal energy, mainly due to their low manufacturing cost, simple design and operation, and maintenance. Their usefulness and the quantitative energy collection has been limited because of low thermal efficiency primarily as a result of low convective heat transfer coefficient, between the absorber plate and air leading to higher plate temperature, and thus resulting in greater thermal losses. One of several methods that have been proposed and investigated for the enhancement of heat transfer coefficient is the use of artificial roughness. Since the use of inclined and transverse wire rib roughness has shown to enhance the heat transfer rate considerably, it is worth exploring. Experimental investigation has been carried out to study heat transfer enhancement by using small diameter wire ribs on absorber plate of solar air heater duct, with the roughened wall exposed to the glazing side while the remaining three walls insulated. The roughened wall has relative roughness height (e/Dh) 0.023, relative roughness pitch (p/e) 11.1, rib height 0.9 mm, angle of attack of 90° for transverse and 45° for inclined configuration, and duct aspect ratio of 12. The air flow rate corresponds to Reynolds number between 2500 – 18,000. Results of the experimental investigation revealed that provision of artificial wire rib roughness resulted in a considerable enhancement in heat transfer and friction factor. It has been found that the heat transfer coefficient could be improved by a factor up to 2.2 and the friction factor had been found to increase by a factor of 1.2 times that of the smooth duct. The investigation emphasized that the secondary flow rolling along the inclined ribs is responsible for higher heat transfer rates. Based on minimum unit energy cost criteria a set of roughness parameters can be selected by the designer for a given operating condition. Key Words: Solar air heater, wire rib roughness, air duct, inclined ribs, unit energy cost. Thu, 01 Aug 2024 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/16591 2024-08-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16590 Optimization of Modified Bach-Type Savonius Wind Turbine With Obstacle Shielding and Deflector Plate Using Gentic Algorithm and NLopt Biniam, Tewbo The Savonius wind turbine is a drag-based vertical axis wind turbine and is used as an alternative source in small-scale energy generation. Design simplicity, low cost, easy installation, good starting ability, relatively low operating speed, and independent wind directions are the main advantages of this rotor. However, because of its low efficiency and high negative torque produced by the returning blade, this rotor concept rarely gained popularity. Over the last few decades, although some investigations around the world have reported performance gains of the Savonius rotor, the available technical design is still not able to fulfill the demand for efficient small-scale wind energy converter at low wind speeds. This study presents a comprehensive computational investigation into the performance enhancement of Savonius vertical axis wind turbines (VAWTs) through optimization in augmentation technique. The research focuses on optimizing the turbine's efficiency and power output by integrating three novel features: obstacle shielding returning blades and deflector plate with a modified Bach blade shape. The obstacle shielding returning blades aim to mitigate the adverse effects of wind obstacles commonly encountered in urban and turbulent environments, while the modified Bach blade shape seeks to improve aerodynamic performance and torque generation. Computational fluid dynamics (CFD) simulations are employed to analyze the flow behavior, pressure distribution, and performance characteristics of the enhanced Savonius turbine design. The study evaluates various design parameters, including blade geometry, obstacle placement, and airflow patterns, to determine their impact on turbine performance metrics such as power coefficient, torque, and rotational speed. This automatic optimization is carried out by coupling an in-house optimization library (OPAL) in Visual Studio compiled with NLopt and SFML with an industrial flow simulation code (ANSYS Fluent). Inlet velocity 9m/s, turbulence intensity 4% and no slip condition consider. K-ω turbulence model used for simulation. A considerable improvement in the performance of Savonius turbines can be obtained in this manner, in particular a relative increase of the power output coefficient by more than 46.5%. It is furthermore demonstrated that the optimized configuration involving A modified Bach-type turbine is good for improvement. KEYWORD: Savonius, modified Bach blade, negative torque, obstacle shielding, deflector plate, CFD simulations Sat, 01 Jun 2024 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/16590 2024-06-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16589 PREDICTING THE CONDITION OF EQUIPMENT USING CBM-BASED RCM ANALYSIS (Case Study of Ries Engineering) Hemen, Zemenu In modern manufacturing, optimizing maintenance strategies is essential for cost reduction, competitive advantage, and product integrity. This study investigates the integration of Condition-Based Maintenance (CBM) and Reliability-Centered Maintenance (RCM) in vehicle manufacturing, focusing on Ries Engineering. The goal is to enhance system efficiency, minimize downtime, and improve reliability by constructing RCM-based CBM model for predicting equipment conditions. Following a Risk Priority Number (RPN) assessment, the study emphasizes the critical status of the EcoSport car's transmission system. It integrates oil analysis (viscosity, wear particles, contamination), vibration analysis (vibration levels, frequencies), and temperature analysis (thermal stress, cooling effectiveness). High RPN values identified critical failure modes: shift timing issues, fluid degradation, and solenoid or sensor failures. Each failure mode was analyzed to determine underlying causes and consequences, leading to targeted maintenance strategies. The results show that combining CBM with RCM will enhances maintenance efficiency, reduces costs, and improves reliability. Shift timing issues were managed through condition-based monitoring, fluid degradation was addressed with regular fluid changes and proactive oil analysis, and solenoid or sensor failures were mitigated with inspections and predictive maintenance. This structured approach significantly boosts operational reliability, extends component lifespan, and optimizes maintenance practices. Future research should validate these findings in real-world settings, implement continuous monitoring systems, provide targeted training, and conduct cost-benefit analyses. Refining the risk matrix and incorporating expert judgment are recommended to advance predictive maintenance capabilities. This study highlights the potential of integrating CBM and RCM to drive innovation in automotive maintenance and enhance overall operational excellence. Keyword: Condition-based maintenance; reliability-centered maintenance Sun, 01 Sep 2024 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/16589 2024-09-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16588 Assessment of Productivity Loss and Forecast Addiction Levels of Khat, In Bahir Dar City. Gashaw, Asnakew Fentie Many companies promote the value of maintaining productivity to ensure the company's continuous financial success. A variety of factors could result in a loss in productivity. Khat chewing during work is a factor in productivity loss. Khat chewing is a daily activity that is extremely addictive and takes billions of hours of work time. The Markov chain model is a stochastic process and an excellent tool for evaluating the state of daily activities. It has led to the assessment of loss of productivity and forecasting of the addiction level of khat in a novel way using the Markov chain model to mitigate negative effects. The data were collected through pre-tested structured questionnaires and interviews. An SPSS version 21 was used for data analysis. The assessment of opportunity cost is an economic expense and productivity loss. The daily loss is 86,840.75 birrs, which is considered an economic burden and productivity loss khat users. The frequency prevalence of chewing the khat once a day was 60.7 %. This study evaluated addiction levels of khat were low, moderate, high, and chronic. In low addiction, 84% continued use in this period, and 16% increased to moderate addiction. At moderate addiction, 69% continued in this period, at high addiction, 93% continued during this period and 5% increased khat chewing by six or more hours. In chronic addiction level, 94% of respondents continued in this period and 5% decreased khat chewing use from four and six hours their khat chewing. POM/QM analysis determined khat addiction levels in the long-term behaviors were 0.5(low), 0.07(mod), 0.48(high), and 0.4(chronic) addiction levels. The long-term probability value of a high addiction level (0.48) is higher than the other addiction levels. To validate the developed model, the chi-square test used that it was greater than the critical value on the significance level (40.4 > 16.919). The results determined the independent variable that grams of khat used have an impact on the developed model of khat addiction levels. The chewing has been taking different chemicals with khat leaves and taking alcohol after chewing khat leaves. In this study, effectively assessed productivity loss and the Markov chain model have been successfully applied to evaluate and forecast future addiction levels of khat chewing. Create awareness about the economic burden and production loss related to khat. give knowledge of the addiction level of khat chewing to make policies and strategies for controlling and preventing khat chewing in the city. Keywords: Addiction level, Evaluate, Forecast, Khat, Markov chain, Prevalence. Productivity loss. Fri, 01 Nov 2024 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/16588 2024-11-01T00:00:00Z