Gebreselassie T.R.,Adama Science and Technology University
Agricultural Engineering International: CIGR Journal | Year: 2014
Dekoko is a cool season legume plant grown in northern Africa. It is a rich source of protein for people in the region. The effect of moisture on some of the physical properties of dekoko seed was studied because it frequently affects some important parameters for the design of mechanical unit operations. The moisture content of dekoko seed was determined according to ASAE standards S352.3 and all other physical properties following standard procedure described elsewhere. The length, width, thickness, geometric mean diameter, thousand seed mass, porosity, true density and angle of repose increased from 5.60 to 6.51 mm, 4.99 to 5.78 mm, 4.60 to 5.44 mm, 5.05 to 5.89 mm, 94.08 to 126.10 g, 39.36 to 48.14%, 1361.66 to 1470.77 kg/m3 and 29.89° to 37.84° respectively. The sphericity increased from 90.05% to 91.14% with increase in moisture content from 10.28% to 19.67% and decreased from 90.83% to 90.55% with further increase of moisture content from 24.42% to 28.61%. Whereas, bulk density decreased from 829.89 kg/m3 at 10.28% to 762.75 kg/m3 at 28.61% moisture content. In the same moisture range, the lowest value of static coefficient of friction recorded when dekoko seed slide against mild steel (0.35 to 0.48,) and the highest value of static coefficient of friction noticed when dekoko seed slide against plywood (0.42 to 0.54). The static coefficient of friction of for galvanized iron increased from (0.37 to 0.51) as moisture increased from 10.28% to 28.61%. Generally, moisture content directly or indirectly affected the physical properties of dekoko seeds.
Borojo D.G.,Adama Science and Technology University
International Journal of Energy Economics and Policy | Year: 2015
This study has applied a recursive dynamic computable general equilibrium model to examine the economic impact of investment on infrastructure for electricity using an updated 2009/10 social accounting matrix. Three simulations (foreign saving, domestic household and enterprises saving and mix of foreign and domestic saving to finance the investment) in combination with total factor productivity of industrial and service sectors are used. The findings of the study have shown the improvement of the real gross domestic product (GDP), output of industrial and service sectors in all simulations. Nonetheless, mixed effects have found on household consumption and trade balance. The highest growth of real GDP is registered when the investment on electricity is fully financed by domestic household and enterprise saving. However, household consumption expenditure has grown at negative rate worsening the welfare of households. Investment on electricity fully financed by foreign saving is resulted in lower growth rate of real GDP due to worsening of net export. In addition, it has benefits for households as it increases their welfare. But it is to be repaid in the future that would increase indebtedness of the country. So, financing the investment partly by domestic household saving and foreign saving would be worthwhile. © 2015, Econjournals. All rights reserved.
Kim M.,Pohang University of Science and Technology |
Heo J.,Pohang University of Science and Technology |
Heo J.,Adama Science and Technology University
Ceramics International | Year: 2015
Glass-ceramic wasteforms containing vitusite (Na3Ce(PO4)2) and Ce-rich crystals were investigated to immobilize lanthanide oxide wastes generated by pyro-processing. Controlled crystallization of alkali borosilicate glasses containing small amounts of P2O5 by heating at T>600 °C for 3 h resulted in formation of vitusite as a major crystalline phase with a minor Ce-rich crystalline phase. Lanthanide oxide waste loading was 11.87 wt%. Rare-earth wastes were efficiently immobilized inside the crystalline phases: lanthanide elements such as Ce and Nd constituted ∼26 wt% of vitusite and 80 wt% of Ce-rich crystals. Amounts of Ce and Nd ions released in a product consistency test were below the detection limit (0.1 ppm) of inductively coupled plasma atomic emission spectroscopy. Glass-ceramic wasteforms that contain vitusite crystals are good candidates to immobilize lanthanide wastes generated by pyro-processing. © 2015 Elsevier Ltd and Techna Group S.r.l.
Gebreselassie T.R.,Adama Science and Technology University
Agricultural Engineering International: CIGR Journal | Year: 2012
Design of unit operations for mechanical and pneumatic cleaning, transportation (conveying), processing and storage of cardamom seeds are dependent on moisture content. Some of moisture dependent physical properties of cardamom seeds were studied at moisture contents 9.9%, 13.57%, 18.41%, and 23.29% wet basis (w.b.). The length, width, thickness, geometric mean diameter, thousand seed mass, and sphericity increased from 17.01 to 17.30 mm, 5.68 to 6.57 mm, 5.02 to 5.35 mm, 7.86 to 8.47 mm, 120.83 to 165.60 g, and 0.46 to 0.49, respectively, with the increase in the moisture content from 9.9 to 23.29% w.b. As the moisture content increased from 9.9 to 23.29% the bulk density, true density, and porosity decreased from 408.2 to 358.90 kg/m 3, 926.57 to787.19 kg/m 3, and 55.94 to 54.41%, respectively. The angle of repose increased from 72.16° at 9.9% to 73.80° at 23.29% moisture content. Whereas, the static coefficient of friction increased with the increase in moisture content from 9.9 to 23.29% on three different surfaces. The highest static coefficient of friction was recorded when cardamom seed against plywood (0.47 to 0.56), and lowest static coefficient of friction against mild steel (0.41 to 0.50). The static coefficient of friction between cardamom seeds and galvanized iron surface increased from 0.44 to 0.53 within the studied moisture content range.
Ashango A.A.,Adama Science and Technology University |
Patra N.R.,Indian Institute of Technology Kanpur
Journal of Materials in Civil Engineering | Year: 2016
This paper presents the stabilization of expansive soil (C) with steel slag (SS), rice husk ash (RHA), and quick lime (L). The geotechnical properties, shearing strength characteristics, and dynamic properties of stabilized soil have been studied. The optimum mix is found to be in the proportion of 65C + 20SS + 5L + 10RHA. The unconfined compressive test shows that strength of treated soil increases about 45 and 90% for uncured and cured samples at 30 days. The soaked California bearing ratio (CBR) test shows that the strength increases with increasing curing periods from 7 to 30 days. Laboratory strain-controlled cyclic triaxial tests have been carried out under undrained conditions to study the dynamic properties of stabilized soil for different strain amplitudes and frequencies. The stiffness of stabilized soil increases to 58-78% as compared to clay soil. This study discussed the suitability of stabilized material for subgrade pavement. © 2016 American Society of Civil Engineers.