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.

Evolution of PAPR Reduction Techniques: A Wavelet Based OFDM Approach

Abstract: Orthogonal frequency division multiplexing (OFDM) is considered among the most suitable multiplexing technique for realizing high speed wireless communication in the present era. Substantially immune to frequency selective fading, high spectral efficiency and superior data rate made OFDM a preferred and popular modulation technique in 3rd generation and 4th generation mobile communication systems. The high value of peak to average power ratio (PAPR) and inter carrier interference (ICI) are the most severe bottleneck for OFDM applications to deliver high performance in communication system. The present work portraits most of conventional and current PAPR reduction techniques through comparative study assisted by simulative analysis which foretells future research potential in wavelet based OFDM to generate more efficient system. PAPR optimization is achieved through hybridization of wavelet with clipping and companding techniques. Different modulation techniques have been analyzed (through Matlab simulation) over proposed hybrid model to observe the PAPR reduction in OFDM system.

Barbers' knowledge and practice about occupational biological hazards was low in Gondar town, North West Ethiopia.

Abstract: Several health hazards including communicable diseases and skin conditions are associated with Barbers’ profession to which their visitors are exposed. Thus, knowledge and practice of Barbers would play a vital part in prevention and control of these health hazards. So, the aim of this study is to assess knowledge and practice, and associated factors among barbers about biological hazards associated with their profession in Gondar town, North West Ethiopia. To assess knowledge and practice, and associated factors among barbers about biological hazards associated with their profession in Gondar town, North West Ethiopia, A work place based cross-sectional study was conducted from March 28 to April 6, 2012. The total numbers of Barbers in the town were 960 of which 400 Barbers were participated in the study. Sample size was determined using the formula for single population proportion by considering, 51% proportion, knowledgeable Barbers from Jimma, Ethiopia, 95% level of confidence, 5% margin of error and 15% none response rate. The numbers of barbers included in the study were selected by using systematic random sampling. Data was collected by face to face interview using a structured and pre-tested questionnaire. Binary and multivariate logistic regression analyses were conducted to identify factors associated with knowledge and practice of barbers. Of 400 barbers, only 72 (18%) had good knowledge about biological hazards associated to their profession, While only 61 (15.3%) were practicing safely during barbering. Knowledge of the barbers was associated significantly with educational level, owner of the business, working hour and work experience, while practice was associated only with availability of UV sterilizers in the room and working hour. Barbers’ practice and knowledge to prevent biological hazards associated with their profession is very poor. Thus, giving training for the Barbers is required toward prevention of biological hazards associated to their profession.

Impacts of climate change on stream flow and water availability in Anger sub-basin, Nile Basin of Ethiopia

Abstract: This study focused on analysis of response of stream flow and water availability that may happen due to climate change in the case of Anger sub-basin (8001.28 km2) in the southern part of the Upper Blue Nile River Basin. A single GCM from Coupled Model Inter-comparison Project Phase 5 with single regional climate model and delta change bias correction approaches combined with SWAT hydrological model were used to project stream flow for the developed scenario over the study periods of 2020s and 2080s including the current conditions. The result indicates that inconsistent increasing or decreasing of water availability was observed. The total annual surface water resource potential of Anger sub-basin estimated at the base period according to this study was about 3.396 BCM/year at current situations. However, the future scenarios in 2020s increasing water availability are shown by 2.71% for RCP 4.5 and negligible decrement shown by 0.14% for RCP 8.5 scenarios. As well as decreasing of water resource was shown by 7.43% and 11.3% at 2080s for both RCP 4.5 and RCP 8.5 scenarios, respectively. This is indicative of the likely future response of stream flow of the study area.

Activity Measurement of the CaS–MnS Sulfide Solid Solution and Thermodynamic Modeling of the CaO–MnO–Al2O3–CaS–MnS–Al2S3 System

Abstract: In order to provide a prediction tool for sulfide/oxide/oxysulfide inclusion evolution in Mn–Al steel with a Ca addition/CaO-based flux, a comprehensive thermodynamic database for the inclusion system composed of CaO–MnO–Al2O3–CaS–MnS–Al2S3 was developed in the present study. Activity of MnS in a CaS– MnS sulfide solid solution was experimentally determined by employing a chemical equilibrium technique at 1 400°C and 1 500°C. The measured activity exhibits a positive deviation from an ideal behavior, which is in consistent with the known two-phase separation of the sulfide solid solution at lower temperature (Tcr = ~ 1 200°C). Based on the activity and the phase diagram data available in literature, a thermodynamic modeling of the CaS–MnS system was carried out. The following excess Gibbs free energy of the CaS– MnS sulfide solid solution was obtained:

Green synthesis of Co-doped ZnO via the accumulation of cobalt ion onto Eichhornia crassipes plant tissue and the photocatalytic degradation efficiency under visible light

Abstract: Nowadays, water pollution is a major concern to the globe. For this reason, various research works has been done to access pure water thereby minimizing the effect of pollutants. In this work, the cobalt doped ZnO (Co-doped ZnO) via the accumulation of cobalt ion onto Eichhornia crassipes plant tissue for different days and combined with zinc precursor was synthesized. The resulting catalyst powder samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and Ultraviolet–vis (UV–vis) spectroscopy, and microwave plasma atomic emission spectrometer (MP-AES). The catalysts were also tested for the photocatalytic degradation of methylene blue (MB) in the presence of H2O2 under visible light irradiation. The best catalytic activity was gained by the 8th-days accumulation of cobalt ion onto the Eichhornia crassipes plant tissue and 99.6% of the dye was degraded within 45 min. However, 69.6, 65.7, 73.6, and 94.8% of MB dye was degraded by 1, 2, 4, and 6 days accumulations. Hence, removal of toxic heavy metal by using Eichhornia crassipes plant and recycling in the wastewater treatment gain is highly appreciated. Moreover, the Co-doped ZnO photocatalysts could enhance the photocatalytic activities due to suppressing of the electron and hole recombination and the porosity of the catalysts resulted from the Eichhornia crassipes plant after calcination.