Adama University

About: Adama University is a education organization based out in Nazrēt, Ethiopia. It is known for research contribution in the topics: Population & Adsorption. The organization has 840 authors who have published 1010 publications receiving 5547 citations. The organization is also known as: Adama Science and Technology University & ቴክኖሎጂ ዩኒቨርሲቲ, አዳማ ሳይንስና ቴክኖሎጂ ዩኒቨርሲቲ.

Development and performance evaluation of a mechanized hand borehole drilling rig in submerged areas of Nigeria

Abstract: Significant of water for agricultural production, be it crop or animal production and even for domestic use cannot be over emphasized. A mechanized hand borehole drilling rig was developed with entire mechanism involve the vertical movement of the drilling bit. The main components of the machine are the power screw, power transmission unit (crown bevel gear), the drilling bit, turning handle and the frame. In operation, as the drilling bit rotate it penetrates the soil until the required depth is attained. A depth of 1m was chosen for the purpose of this study and if more drilling pipes are provided, a depth of 4-6m can be achieved. A performance test was carried out on the rig and an average depth of 1.8m was attained in 15 minutes for sandy soil, 1.7m in 20 minutes for sandy loam and for clay soil, an average depth of 1.2 m for 23 minutes was also achieved. The constructed drilling rig uses human power to operate and for this reason it can only be used for shallow borehole drilling, where the water table is close to the surface. A device of this nature can be manufactured in small workshop to aid water supply in small farms especially during dry season, mostly in the rural areas. Hence the outcome of the research will help further researches water availability and its predicaments.

Wind Energy Conversion System Model Identification and Validation

Abstract: Wind energy conversion system (WECS) is complex because of wind speed varies in time and space. Model identification is required to represent its dynamics for real-time implementation. In this paper a doubly-fed induction generator (DFIG) WECS is used. Different model structures are generated and simulated using MATLAB/SIMULINK. The models are generated using both nonlinear and linear system identification tool boxes. Linear system identification toolbox generates both model structure and model parameters; whereas the nonlinear system identification tool generates only the system model structures. From linear models, the BJ33221 model has better performance with best fit of 74.78%, final prediction error (FPE) value of 0.0445 and mean square error (MSE) is 0.04265. ARX211 model structure provides best fit of 74.39%, FPE of 0.0453, and MSE is 0.04465. This study shows as model order increases, the best fit value too, but the system become more complex. The nonlinear models have better performance than the linear models. The nlarx121 model structure provides the best fit of 96.43% and MSE of 0.0322, with other technique for its model parameters estimation. The output residuals are within the confident range (0.2 to −0.2), indicating the model structure was validated.

In vitro regeneration of Allophylus serratus. Roxb (Kurz), an important medicinal plant

Abstract: Abstract Background Allophylus serratus Roxb (Kurz.) is a medicinal plant with various therapeutic properties. It has been used for the treatment of various alignments such as elephantiasis, edema, fractured bones, in bone dislocations, wound, several gastrointestinal disorders such as dyspepsia, anorexia, and diarrhea. The aim of this study is to establish protocol for surface sterilization, in vitro callus induction and plant regeneration from leaf and nodal segment explants of Allophylus serratus. Results From the tested media, the maximum callus induction frequency (81.11%) from leaf and 84.44% from nodal segment explants were achieved on MS medium supplemented with 3 mg l − 1 BAP) combined with 0.5mgl − 1 NAA. The highest shoot regeneration frequency (57.78%) and root regeneration frequency (65.55%) were achieved on growth regulators free MS medium and MS medium supplemented with 1.5 mg l − 1 IBA respectively. Acclimatization of the regenerated plantlets was established successfully (100%) in a pot containing sand, soil and compost in 1:2:2 ratios. Conclusions In this study successful callus induction protocol from leaf and nodal explants of A. serratus using MS media supplemented with different concentrations and combinations of plant growth regulators (2,4-D, NAA, and BAP). MS media containing 3mg/l BAP and 0.5mg/l NAA was the most efficient for callus induction. these callus induction and plant regeneration protocols are very important for mass propagation of the species and also opens a new way to facilitate secondary metabolites production and isolation of pharmaceuticals from callus rather than harvesting the plant.

Optimization of Friction Welding Process Parameters for Weldment of Aluminium–Copper Electrical Connector

Abstract: Friction welding of aluminium and copper has been widely used in electrical transmission in production of bimetallic (lug) or connectors. The use of dissimilar metal connector is to prevent high electrical losses due to contact resistance and mechanical contact between aluminium and copper which is not permanent in their application for the fact of environmental degradation. Galvanic corrosion between the two metals in mechanical contact is saviour and it is technically distractive; hence friction welding of the two metals solved the problem by introducing technically acceptable joint between the two metals. Mechanical strength of the connectors has been very important to withstand stress caused by heat and mechanical force. Electrical resistance behaviour has also been highly important. The aim of this research has to optimize process parameters that gave the best electrical and mechanical properties of the weldment. The selected materials and method are different and unique from any other studies. Optimization of welding parameter that gave two characteristics of their performances such as strength and electrical resistance when optimized successfully. Grey relational analysis, ANOVA and Taguchi method have been used for the optimization process. Vertical drilling machine was used for the friction welding process and the machine was 1.7 KW power with the rotational speed of 3060 RPM. The optimization of the process parameters of the friction welding, i.e. RPM, friction pressure and friction time was conducted. The obtained optimum setting for two performance output characteristics such as strength and electrical resistance was friction time at 20 seconds, friction pressure 117 (MPa) and 1050 (RPM). Furthermore, based on two performance studies, friction pressure has a basic parameter that determined the desired response.