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.

Multiple modeling to estimate sediment loss and transport capacity employing hourly rainfall and In-Situ data: A prioritization of highland watershed in Awash River basin, Ethiopia

Abstract: In present study, the sediment yield/loss and Transport Capacity (TC) has been estimated in a highland watershed of Adama Woreda, part of Awash River Basin in Ethiopia. For the study, average hourly 14 years rainfall data obtained from different gauging stations in the study area during 2001–2014 was utilized to calculate rain erosivity (R factor). Subsequently, soil erodibility K, length-slope LS factors of Revised Universal Soil Loss Equation (RUSLE) were adopted for the calculation of WATEM/SEDEM sediment delivery algorithm. The average R factor value for the watershed was evaluated as 2075.27 MJ/ha mm/year. The grid based KTC (Transport Capacity Coefficient) was determined for the WATEM/SEDEM sediment transport estimation through the results of Soil Water Assessment Tool (SWAT) and Revised/Modified USLE. The SWAT simulated suspended solids (SS) versus two years (2013 and 2014) rainfall measured records at single observatory was used for the SWAT calibration and validation. The SWAT sediment yields and Transport Capacity (TC) were used to determine the KTC at each sub-watershed. The mean value of KTC was estimated 8.033 and minimum and maximum values were found 0.080 and 51.49 respectively. Moreover, the Sediment Deliver Ratio (SDR) model equation was calculated and resulted values were found >0.7 in the main streams. For the prioritization, sediment yield and loss estimated values using Sediment Yield Index (SYI) and RUSLE along with SWAT models were employed. The results generated through these models were averaged and accordingly the ranks and severity classes were determined.

Modeling and control of a Doubly Fed Induction Generator using a back-to-back converters in grid tied wind power system

Abstract: The demand of energy is drastically increasing now days mainly in developing countries like Ethiopia. In connection, wind energy is one of the promising renewable energies sources with the most commonly used Doubly Fed Induction Generator (DFIG). The DFIG's stator is directly connected to the grid, whereas the rotor is tied via dual back-to-back Pulse Width Modulation (PWM) converters. Its active and reactive power can be controlled independently using converters as per the demand of system operators or grid code requirements. The PWM strategy has a capacity of giving higher converter output voltage by high switching frequency modulation process. Thus, this paper models the DFIG and uses PWM to control the power flow at rotor and grid sides independently. MATLAB-Simulink software is used for modeling and simulation. Finally, conclusions are drawn.

Curie depth estimated from high-resolution aeromagnetic data of parts of lower and middle Benue trough (Nigeria)

Abstract: To quantitatively understand the geodynamic process of a region, study of geothermal parameters underneath the earth surface is very paramount. Curie depth can be an alternative to delineate geothermal parameters. In the present study, we estimated Curie depths from the power spectra of 25 equally window sizes areas/points with 50% overlap extracted from high-resolution aeromagnetic anomalies of parts of lower and middle Benue Trough, Nigeria using modified centroid method based on fractal distribution of magnetic sources. Curie depths with associated uncertainties calculated from the region under study are between 11 ± 2 and 27 ± 2 km. The shallowest depth (11 ± 2) km is calculated around the area of Abakaliki whereas the deepest depth is calculated around Otukpa area of Anambra basin. The shallowest Curie depth as calculated is related with the Abakaliki anticlinorium while the deepest result is in connection with the Anambra basin. These suggest that different geological structures and magnetic anomalies (i.e. high or low magnetic anomaly) influenced the calculated Curie depth results. In the region, it is noted that lower Curie depths (14–18 km) are recorded over the basement rocks and Curie depths between 18 and 22 km within zones of volcanoes. The interpretation hypothesized presence of underplating in the crust and possibly mantle plume as a result of the Mesozoic–Cenozoic volcanic magmatism (magmatic centers) mostly basalts distributed and scattered in the region. It has also been hypothesized that the uncertainties calculated (± 0.2 to ± 5.0) in the region correlate more strongly with the geology, tectonic structures and type of anomalies than estimated Curie depths.