The majority of the antimicrobial compounds used for treating textiles are synthetic based and are not considered to be environmentally friend. Therefore, solanum incanum fruit and onion peel were selected for the current study based on its potent antimicrobial activity. The active substance was extracted from fruit and peel by using the maceration extraction technique for 7 days with mass to solvent ratio of 1:10. The solanum incanum fruit and red onion peel extracts were applied alone and together, on the cotton fabric samples by the pad-dry-cure method, using citric acid as a cross-linking agent. The antibacterial activity and the wash durability of the treated cotton fabrics were assessed by AATCC 100-2004 method. Among all treatments, the cotton fabric treated with 50:50 combinations were found to be more in bacterial reduction. It was 100% and 99.92% bacterial reduction in cotton fabric with 5g/l concentration for S. aureus and E. coli respectively. The wash durability of fabric treated with 50:50 combinations was 85% for S.aureus and 84.17% was for E.coli bacteria after 15 wash cycle. After treatment, the tensile strength air permeability, bending length, water absorbency and soil degradation were tested. Air permeability, water absorbency, and tensile strength were decreased. Soil degradation tests proved the biodegradability of the treated sample. The result recommended that the use of herbal extract could potentially be used as a substituent to a synthetic agent.
Authors: Tesfa Gesese (Bahir Dar Institute of Technology, Bahir Dar University,Bahir Dar, Ethiopia), Solomon Fanta (Bahir Dar Institute of Technology, Bahir Dar University,Bahir Dar, Ethiopia), Desalegn Mersha (Bahir Dar Institute of Technology, Bahir Dar University,Bahir Dar, Ethiopia),
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This study aimed to evaluate the anti-Picornaviruses, anti-influenza A and B viruses and anti-dengue activity of Aloe pirottae root in Vero cell line. In this study, crude methanol extract (MeOH) and its organic solvent fractions including n-hexane (HxF), chloroform (CHF), ethyl acetate (EAF) and n-butanol (BuF) of Aloe pirottae root in different concentrations was evaluated by a cytopathic effect (CPE) inhibitory assay for influenza virus and picornavirus and an immunofluorescence assay (IFA) for dengue virus. In vitro test revealed that Aloe pirottae root have significant effects in reducing both type A and B influenza virus, both type HRV B14 and EV-71(H) Picornaviruses and DENV-2 replication in MDCK cells. EAF exhibit more potent inhibitory activity with selectivity index >7.2 > 17.8 and >8.5 than positive controls AMT with selectivity index not determined (ND), >47.6 and ND and RBV with selectivity index > 2.9, > 5.3 and > 5 against PR8, HK and Lee, respectively. EAF exhibits the strongest anti-HRV B14 and anti-EV-71(H) activity in MDCK cells. Crude MeOH extract, EAF and BuF at both concentrations exhibit strong inhibition of DENV-2 induced CPE whereas CHF and HxF at both concentrations exhibit strong inhibition of DENV-2 production. The findings shows significant inhibitory effect of Aloe pirottae root on influenza A and B viruses, both type HRV B14 and EV-71(H) Picornavi-ruses and DENV-2 growth in Vero cell line.
Authors: Anuradha G (Assistant Professor), Akalu Terfa (Lecturer), Hailemicahel Tesso (Assistant Professor), Young Jung (Professor),
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In the recent years, bioethanol derived from lignocelluloses biomass as an alternative to the conventional fuels is becoming a focus of many researchers. In this study, bamboo is used as a feedstock for the production of bioethanol via alkaline pretreatment followed by, enzymatic and acid hydrolysis process. Specifically, the focus is mainly on the investigation of the effect of alkaline pretreatment on the yield of total fermentable sugar from bamboo (yushania alpine) biomass using sodium hydroxide as a catalyst. Alkali concentration, pretreatment temperature, and reaction time were varied in the alkali pretreatment experiments. Following the pretreatment, enzymatic and dilute sulfuric acid hydrolysis of the pretreated bamboo were carried out separately to measure the success of the alkaline pretreatment in improving the total reducing sugar yields. The composition of raw and pretreated bamboo were characterized using NREL and ASTM protocols.It was found that, the raw bamboo has a composition of 42.45 % cellulose, 23.6 % hemicelluloses, and 32.4% Lignin.The alkali pretreatment resulted in a maximum lignin removal of 35.5% at temperature of 60oC, contact time of 50 min, and alkali concentration of 4.5% w/v, which leads to an increment of cellulose fraction to 64.93% and reduction of lignin to 20.8%. A maximum total reducing sugar yield of 206.3 mg/g and 351.9 mg/g were obtained for pretreated bamboo by using enzymatic and dilute sulfuric acid hydrolysis, respectively.
Authors: Netsanet Alemayehu Bitew (Department of Chemical Engineering, Institute of Technology, University of Gondar), Yalew W/Amanuel (2College of Biological and Chemical Engineering, Addis Ababa Science and Technology University), Nigus Gabbiye Habtu (Bahir Dar University, Bahir Dar Institute of Technology),
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Ground water have been under increasing threat of pollution in recent years due to improper management of vast amount of wastes generated by various human activities. Improper dump sites have served many years as ultimate disposal site for all types of waste; municipal solid waste, industrial sewage and hazardous waste in developing countries such as Ethiopia. Physical, chemical and biological processes interact simultaneously to bring about the overall decomposition of the wastes. If not deal properly such kind of dumping site can cause pollution to groundwater (because of Leachates) and surface water (through contaminant transportation by flooding and ground water movements). Therefore, this study investigates the spatial and temporal variation of ground water quality within the Chilanchil Abay water shade during dry and wet season due to waste disposal site of Bahir Dar city. Water samples were collected from6 sampling points of ground water from 30th march to 20th august by monthly period. Over 15 water quality parameters such as pH, TDS, Electrical conductivity, Turbidity, Temperature, DO, TH, BOD, COD, TC, NO3- , PO43-, Cr, Mn and Pb were analyzed. Moreover, the overall status of the ground water quality of the study area was evaluated by Canadian Water Quality Index. The analyzed result showed that the Chilanchil Abay water shade water quality status ranges from 42 to 46.2 for ground water (marginal status).
Authors: Dargie Molla (Lecturer of Chemical engineering (master’s degree in Environmental engineering). Department of Chemical Engineering, Institute of technology Woldia University, Ethiopia. E-mail: dargiehaile3@gmail.com.P.O. Box 400. 2), Nigus Habtu (Associate professors of chemical, Environmental and Process Engineering, Reginal coordinator for the PHL - IL project feed the future innovation Lab, department of chemical engineering, Bahir-Dar institute of technology Bahir-Dar University, Ethiopia. E-mail:),
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The paper examined the possibility of substitution of fire wood by sawdust briquettes. Easy to operate and portable homemade briquetting machine was fabricated. Three diameters of molding cylinder/ die diameters specifically 6, 8 and 10 cm were used to examine the effect of pressure on quality of sawdust briquettes. For all types of sawdust briquettes, the highest and lowest values of density, porosity index, volatile matter, ash content, fixed carbon and calorific value are 218.24-322.62kg/m3, 33.97- 312.4%, 70.24-90.56%, 2.33-7.26%, 6.7-24.26% and 14.5019-18.3832MJ/kg respectively. The figured physical and chemical properties of sawdust briquettes were interesting. Density and porosity index of sawdust briquettes were extensively affected by molding cylinder diameter and waste paper percentage. An interesting quality of sawdust briquettes was attained at lower particle dimension, waste paper percentage and at higher pressure. The optimum value of density, porosity index, percentage volatile content, percentage ash content and gross calorific value of 306.079 kg/m3, 35.92 %, 83.90 %, 3.05 % 17.134 MJ/kg respectively were acquired at combination of die diameter of 6 cm and waste paper percentage of 25 %. Capability of production of sawdust briquettes with good quality using only waste paper as a binder is an encouraging fact and the briquettes can be an excellent substitutes augments to firewood.
Authors: Muluken Mengist Moges (University of Gondar, Institute of Technology), Belay Woldeyes (Addis Ababa University, Addis Ababa Institute of Technology), Nigus Gabbiye Habtu (Bahir Dar University, Bahir Dar Institute of Technology),
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Dyes extracted from natural sources have appeared as important substitutes to synthetic dyes. The aim of this study was to extract eco-friendly natural dye from the root of Rumex Abyssinicus (Mekmeko) by using an aqueous extraction method. The extraction was performed in the acidic, basic and neutral medium at temperatures of 40oC, 60oC and 80oC for 1 hour. The best condition for dye extraction was obtained in a basic medium at a temperature of 80oC for 1 hour with absorbance of 0.783 at 428nm. UV-Visible scan of extract from 200 to 800 nm showed a maximum absorbance peak (λmax) detected at 278.18nm with an absorbance of 0.67 in UV region. The FTIR anal-ysis test confirmed the presence of chromophores (color bearing groups) compounds like carbonyl (C=O) and nitro (NO2). The coloring potential of the extracted dyes has been studied using selected mordant types such as aluminum sulfate, iron sulfate, and copper (II) sulfate applied on fabric cotton and tanned leather. Evaluation of the colorfastness on the dye properties was assessed by evaluating washing and rubbing fastness. The dyed cotton fabric showed a good to excellent washing and rubbing fastness rating whereas the non-mordanting cotton fabric showed poor colorfastness. Dyed tanned chrome leather showed good to excellent grade washing and rubbing fastness in both mordanting and non-mordanting conditions.
Authors: Melkamu Birlie,
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There are very limited studies regarding the causes and extent of postharvest losses of tomato in Northwest Ethiopia. The aim of the present study was to determine quantitative postharvest loss of tomatoes along the supply chain in Northwest Ethiopia. The study was conducted in three productive kebeles, Chimba, Gumara, and Kudmi of Northwest Ethiopia following the FAO load tracking method. Key informant interviews were conducted to document common pre-harvest practices of tomato in the study kebeles and an experiment consisting of 3x4 factorial design considering growing locations and supply chain was conducted to determine quantitative postharvest losses of tomato along the supply chain. Postharvest losses of tomatoes ranged from 6.17-8.62%, 1.23-8.24%, 3.35-4.30%, and 9.38-12.58% at the farm, transportation, wholesale, and retail levels, respectively. The average total postharvest loss of tomatoes was 25.91±1.04% along the supply chain. Inadequate pre-harvest management, inappropriate harvesting time and method, lack of appropriate harvesting and packaging containers, lack of on-farm storage facilities, poor road access and infrastructures, inappropriate mode of transport, lack of storage facilities at wholesale and retail levels, and lack of reliable market system and market information were also identified as contributors for the high losses of tomatoes recorded in our study.
Authors: Eskindir E. Tadesse (Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia), Hirut Assaye (Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia), Mulugeta A. Delele (Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia), Solomon W. Fanta (Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia), Dawit F. Huluka (Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia), Melkamu Alemayehu (College of Agriculture and Environmental Sciences, P.O. Box 5501, Bahir Dar University, Bahir Dar, Ethiopia), Getachew Alemayehu (College of Agriculture and Environmental Sciences, P.O. Box 5501, Bahir Dar University, Bahir Dar, Ethiopia), Enyew Adgo (College of Agriculture and Environmental Sciences, P.O. Box 5501,Bahir Dar University, Bahir Dar, Ethiopia), Jan Nyssen (Department of Geography, Ghent University, Krijgslaan 281 S8, B-9000 Gent, Belgium), Pieter Verboven (BIOSYST-MeBioS, KU Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium), Bart M. Nicolai (BIOSYST-MeBioS, KU Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium),
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Drying is the oldest method of food preservation. However, the drying method can adversely affect product quality. The present work aims to measure the texture, color, vitamin C and β-carotene content of solar, oven and integrated solar-oven drying of apple and kent mango slices. Micro stable texture profile analyzer (TPA), spectrometer and UV-Vis spectrophotometer were used to determine the texture, color, vitamin C and β-carotene content, respectively. The result shows variety had a non-significant effect (p>0.05), while the drying method has a significant effect (p<0.05) on the texture and color values of dried mango slices. The mango slice structure was become harder in texture and darkens in color. Apple (72.38mg/100g, (91.05µg/100g) and kent mango (66.72mg/100g, 73.80µg/100g) showed a significant difference (p<0.05) on their vitamin C and β-carotene content. The loss of vitamin C (58.41mg/100g) and β-carotene (58.60µg/100g), was low in the integrated solar-oven dryer. The loss of vitamin C was high in kent mango than the apple mango, while the β-carotene lost was high in apple mango than the kent mango. This study indicates that the use of integrated solar-oven drying was the preferred drying method to keep vitamin C and β-carotene loss minimum.
Authors: Tadlo Atlog (Bahir Dar University), Tadesse Yehuala (Bahir Dar University),
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Nanomembranes are important class of nanomaterials, with significantly advancing applications in a wide range of applications, including molecular separations, energy conversion and storage, sensing, catalysis and biomedical applications such as wound dressing, owing to their nano-scale thickness and high aspect ratios. However, in order to exploit the unique features of self-supporting nanomembranes (transferability onto any arbitrary substrate, high aspect ratio and unique interfacial properties), they need to have sufficient mac-roscopic stabilities. Conventional mechanical enhancement approaches, such as use of nanoparticle fillers often face material compatibility problems, limiting the range of material selection. In this work, a simple one-step strategy for de-veloping functional free-standing nanomembranes (FS-NMs) from blended types of organic/inorganic composites has been presented. Such blending approach offers atomic scale in-situ interaction of organic and inorganic structures, ensuring nanoscale stability in membranes. Here, a hydroxyl-terminated polyethylene glycol (PEG-OH) was premixed with different metal oxide pre-cursors for sol-gel assisted membrane formation, and the mechanical properties of the resulting FS-NMs were compared. The gas separation behavior of me-chanically stable nanomembranes was also discussed. The presented strategy offers an alternative approach to develop functional self-supporting nanomem-branes.
Authors: Anteneh Mersha (Department of Industrial Chemistry, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia),
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The photocatalytic activity of graphitic carbon nitride (g-C3N4) is limited as a re-sult of insufficient visible light absorption and fast electron–hole recombination. In this work, we synthesized Porous g-C3N4 using facile polycondensation meth-od. The physicochemical and structural properties of the prepared g-C3N4 sam-ples were characterized using XRD, DRS, PL, FTIR, Raman spectroscopy, SEM, BET specific surface area and the CHN elemental analyzer. The prepared g-C3N4 showed extraordinary photocatalytic activity towards photodegradation of rhodamine-B (RhB) under visible light irradiation. Out of the prepared g-C3N4 samples, the g-C3N4-550 exhibited photodegradation efficiency of 100 % to-wards the RhB pollutant in water within 30 min. No appreciable decrease of the photocatalytic efficiency of g-C3N4 was observed up to five consecutive cycles, confirming the prepared g-C3N4 was highly stable. Thus, this work provided a simple method for mass-production of highly photoactive and stable g-C3N4 ma-terials for environmental remediation.
Authors: Gebrehiwot Gebreslassie (Department of Industrial Chemistry, College of Applied Sciences, Addis Ababa Science and Technology University, Addis Ababa 16417, Ethiopia), Pankaj Bharali (Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784028, India), Gebremedhin Gebremariam (Department Chemistry, College of Natural and Computational Sciences, Mekelle University, Mekelle 231, Ethiopia), Assefa Sergawie (Department of Industrial Chemistry, College of Applied Sciences, Addis Ababa Science and Technology University, Addis Ababa 16417, Ethiopia), Esayas Alemayehu (Faculty of Civil and Environmental Engineering, Jimma University, Jimma 378, Ethiopia),
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Natural fibers have received significant research attention at global level because of their advantages, environmentally friendliness and cost-effectiveness. Among various natural fibers, water hyacinth is one of the cheapest fibers. The water hyacinth has not yet been used as reinforcing material for composites. The goal of this research work is to fabricate water hyacinth fiber reinforced polyester composites with an objective of characterizing the mechanical properties of water hyacinth fiber reinforced composite. The composite of water hyacinth fiber is fabricated with polyester resin, using hand lay-up methods in different fiber/matrix ratios. The mechanical properties of the specimens were then measured according to ASTM standard recommendations and the prepared composite materials were tested tensile, flexural and compressive experimental tests. The results show that 20% fiber content is around optimum content for best mechanical behavior and all the mechanical properties are satisfactorily improved when the water hyacinth polyester composite is chemically treated using NaOH. Therefore, using water hyacinth fibers as reinforcement in a polymer matrix, it has been proved that successful composites can be developed.
Authors: YOHANNES REGASSA (Addis Ababa Science and Technology University), Samirawit Alemayehu (Addis Ababa Science and Technology University), Bisrat Yoseph (College of Engineering), Hirpa G. Lemu (University of Stavanger, Norway),
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This study aimed to investigate the effectiveness of liquid membrane – forming concrete curing compounds produced in Ethiopia. Curing in local construction sites, challenges a problem such as ineffective curing, omission of continues curing and using not pure water for curing. Drying time, deleterious reaction, compressive strength (on C-25 and C-40 grades of concrete) and water absorption tests were carried out.The test samples of compressive strength and water absorption are examined under laboratory conditions which were cured through immersion curing and curing compounds and by exposing samples to external weather conditions which were cured through curing compounds, water sprinkling and plastic sheet covering. Economic cost comparisons between two conventional curing methods (water sprinkling and burlap covering) and applying curing compound is the other aspect of this research. Liquid membrane – forming concrete curing compounds produced in Ethiopia are effective in compressive strength but not in water absorption. Also, liquid membrane – forming curing compounds are cost effective following water sprinkling method of curing. Water sprinkling and plastic sheet covering methods were effective in compressive strength than curing compounds.Water absorption tests also showed that that immersion curing, plastic sheet cover and water sprinkling lead to better concrete quality than curing compounds. Water sprinkling is less costly but Curing compound is costlier.
Authors: Rahel Alemu (PG Student, Department of Construction Technology and management, Bahir Dar Institute of Technology, Bahir Dar University, Ethiopia), Kassahun Admassu (Ethiopian Institute of Architecture, Building Construction and City Development, Addis Ababa university, Addis Ababa, Ethiopia),
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Shoe polish is a type of waxy paste that used in gloss, rub resistance, resistance to fading and dust by providing a thin film on the surfactants of the shoe. In this research work, new shoe polish was prepared from 5-gram cactus and 5-gram charcoal powders in 75:25 mL wax to olive oil ratio in the presence of denatured alcohol and benzene at an optimized procedure. Furthermore, this prepared shoe polish was subjected to different quality analysis parameters such as viscosity, density, melting point, reflexive index, pH value, ash content, conductivity and moisture content in the comparison of with purchased shoe polish (Kiwi). As the results of these tested parameters indicated, the prepared shoe polish has shown a comparable result with purchased shoe polish (Kiwi). The functional group of the prepared shoe polish was also identified using FTIR analysis and the FTIR peaks confirmed that the presence of long-chain ester groups in prepared shoe polish. This ester group is responsible for quick-dry and good smells. Besides, the practical use of the prepared shoe polish and purchased shoe polish were examined by polishing some shoes with these shoe polishes. The prepared shoe polish exhibited a very good gloss, dust adsorption resistance, fading resistance and rub resistance just after three wearing days. Thus, the prepared shoe polish is fulfilled the quality parameters and replaceable the commercially available shoe polish on the market.
Authors: Tessema Hailegebreal (Wachemo University), Tassew Alemayehu (2Department of Chemistry, Adigrat University), Dinku Senbeta (Adigrat University),
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Currently, there is an expanding demand of composite materials for various engineering applications. Glass fiber reinforced polymer composites, prepared by an injection molding, is among these composites. Injection molding method has basic process parameters which determine the mechanical behaviors of polymer matrix composites (PMCs). However, only few studies have been reported on the effects of process parameters of injection molding of glass fiber reinforced polypropylene composites. In this study, process parameters such as melting temperature, mold temperature, packing pressure and flow rate were used during manufacturing of specimens. The modeled specimens, loaded by a compression force, were simulated and analyzed using moldflow (R2018) and ansys (R19.2) software. The specimens were subjected to compression testing to study the effects of process parameters on mechanical properties of the composites. As a result, it is found that fiber orientation, deflection and mechanical properties of the composites are significantly affected by the process parameters. So, in pursuit of increasing the mechanical properties of the composites, 200c mold temperature, 2100c melt temperature, 60cm3/s flow rate and 40 MPa packing pressure are required. From the results, more influences are registered by melt temperature than the remaining process parameters.
Authors: Eshetie Adugna (Ethiopian Institute of Technology -Mekelle, Mekelle University, Tigray, Ethiopia, P.O. Box: 231), Frederik Desplentere (ProPoLiS research group, KU Leuven Bruges Campus, Spoorwegstraat 12,B-8200 Bruges, Belgium), Temesgen Yallew (Ethiopian Institute of Technology -Mekelle, Mekelle University, Tigray, Ethiopia, P.O. Box: 231), Bart Buffel (ProPoLiS research group, KU Leuven Bruges Campus, Spoorwegstraat 12,B-8200 Bruges, Belgium),
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Power-line communication (PLC) reuses electric signal carrying power-lines to carry information bearing signals. Since PLC channels are primarily designed to carry low frequency electric signal, they pose harsh conditions for transmission of high frequency communication signals. Impulsive noise (IN) and frequency selective fading, due to multipath characteristic of PLC channels, are the primary challenges in PLC. Orthogonal frequency division multiplexing (OFDM) is successful in reducing the effect of both challenges up to a certain level of noise energy in the system, beyond which it needs to be augmented by other mitigation techniques to reduce error, which is primarily caused by IN. In this work, Turbo codes and hybrid nonlinear preprocessors are proposed and to be applied together to combat IN in OFDM-PLC systems. Error performance of an OFDM-PLC system with the proposed scheme applied is investigated for various levels of PLC channel impulsiveness. It is found that Turbo code plus hybrid preprocessors achieve better error performance than previously applied IN mitigation techniques of Turbo code plus blanking and Turbo code plus clipping.
Authors: Fikreselam Mengistu (Bahir Dar University),
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In the bandwidth demanding world, TV white space is becoming one of the best options. Its use as a secondary system with incumbent system must be managed in order not affect the primary users. This can be done by determining first the incumbent coverage and then the spatial variation that should be kept in order to maintain unaffecting region. Our primary concern is keeping the incumbent users safe. This is accompanied by different methods to keep the secondary device non interfering. The interference can be avoided by efficient cognitive radio technique or spatial variation between the two systems. The second technique requires efficient signal modeling and planning. The secondary system should be deployed in an area that is out of primary coverage. This is done by first determining the incumbent coverage. To determine this coverage, different factors must be taken in to account. Frequency and antenna height are the most significant factors. After the signal range of primary transmission with receivable quality is determined, we have determined another reserved distance that a secondary device should be kept away in its active status, without affecting the incumbent system. This is what is known to be reserved distance. From the most significant factors in determining the spatial variations, we have found transmitter antenna height to be the most significant factor in white space system planning.
Authors: Tessema Terefe (Addis Ababa Science and Technology University), Habib Hussien (Addis Ababa Institute of Technology), Sultan Meko (Addis Ababa Science and Technology University),
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Ethiopia is one of coffee producing countries in the world, especially it is known for coffee Arabica. The coffee supply chain includes different participating organizations from its production place up to its consumption in the international market. Ethiopian coffee suffers from the two most prominent supply chain problems which are provenance traceability and transaction transparency for the participating parties. In this paper, we tried to implement blockchain technology for the Ethiopian green coffee supply chain to improve traceability and transparency by using Sidama coffee as case study. Distributed ledger technology was proposed to solve those problems by distributing a record of coffee transactions throughout the network participants. Among available blockchain technologies, we choose Hyperledger blockchain technology because it is suitable for business to business (B2B) model. We were able to design and implement a number of smart contracts using Hyperledger composer modeling language based on our field study and deploy them in the underlying Hyperledger Fabric blockchain network. The prototype system was able to create a traceable route for the coffee by recording every transaction in an immutable and untampered way and the transactions were transparent for participating parties since they get an exact copy of ordered transaction as a block. We also were able to solve confidentiality issues in the network by implementing multiple channels in the network.
Authors: Temesgen Abebe (Bahir Dar University/Institute of Technology/Faculty of Electrical and Computer Engineering), Alehegn Semegn (Bahir Dar University/Institute of Technology/Faculty of Mechanical and Industrial Engineering),
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In computer security Intrusion Detection System (IDS) is a mechanism of detecting an intruder in the system and notifying malicious activities for system administrators. The IDS researches on wireless Local Area Network (LAN) started recently. Until now there are some researches like publishing Aegean Wi-Fi Intrusion Dataset (AWID) dataset publically for the research community and evaluating the dataset using different machine learning algorithms. But the wireless IDS is not well researched and it needs further scientific investigation for performance improvement. In this paper, we propose Deep Belief Network (DBN) to evaluate AWID dataset for intrusion detection analysis. Since AWID dataset contains different data types which are numeric, string, and hexadecimals; before training the model and evaluation of its performance the dataset is preprocessed and finally 102 attributes are used for system training. Also, two-stage feature selection is implemented to reduce the training cost and improve system performance. The first stage is removing duplicated attributes which reduced the dataset size to 68 attributes. The second stage is done by applying Weka implemented Information Gain Ratio (IGR). Using three thresholds three datasets are prepared with 41 attributes, 34 attributes, and 25 attributes. The system was able to achieve 98.55% accuracy with 102 attributes and it was able to improve this result to 98.97% with selected 34 attributes set evaluation.
Authors: Temesgen Abebe (Computer Engineering), Menore Mengistu (Computer Engineering),
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Next generation networks are expected to provide a wide range of services and functionalities. These services have imposed different requirements at the physical layer. Due to ease of implementation, immunity to interference and high data rate support, orthogonal frequency division multiplexing (OFDM) have been the most promising multicarrier waveforms for the development of recent wireless networks. Whereas, to provide the expected requirements in next generation networks, more advanced multicarrier modulation techniques are required. Hence, other candidate multicarrier modulation techniques have been proposed to address the challenges of OFDM. In this work, we evaluate and analyze the performances of candidate multicarrier modulation techniques for next generation networks such as filter-bank multicarrier (FBMC) and universal filtered multicarrier (UFMC). To obtain insightful analysis, we first analyze the basic principles and characteristics of each multicarrier modulation technique. Then, we compare their performances in terms of power spectral density (PSD), bit error rate (BER) and spectral efficiency. Besides, the computational complexity of the proposed multicarrier modulation techniques is evaluated. Finally, numerical simulation is done to validate the theoretical analysis. The results show that FBMC has minimum out-of-band (OOB) emission and this helps to be almost insensitive to multiuser interference to support different use cases in the same bands.
Authors: Amare Yimer (Addis Ababa University, Bahir Dar University), Fikreaddis Tazeb (Addis Ababa University), Dereje Woldegebriel (Addis Ababa University), Fikireselam Mengistu (Bahir Dar University),
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Demand for enhanced mobile broadband has been increasing due to increasing penetration of data-intensive services. For accommodating this demand, various network capacity enhancing technologies including cell densification have been investigated and incorporated in 5G. Cellular network densification can be performed either by deploying small cells or further sectoring horizontally and vertically existing network sites. Various literatures investigate performance benefits of vertical sectorization based densification but considering theoretical network environment and user distribution. In this paper, we present performance analysis of vertical sectorization under realistic network environment and user distribution for selected area of Addis Ababa, Ethiopia. The analysis is performed for sub 6 GHz bands including the new 5G bands. Network simulation is undertaken using Matlab while network modeling and assumptions are developed based on data collected for selected area from network management system of Addis Ababa network. Propagation is computed using deterministic 3D ray tracing method based on building map for the selected Addis Ababa area. Performance metrics of 10 % tile, 50% tile and 90 % of CDF of SINR and their modified Shannon mapping in realistic environment are examined. This configuration enhances system performance up to 513.11% and 982.03% of user throughput at 10%-ile and 50%-ile compared to the existing 3x1 configuration.
Authors: Seifu Zeleke (AAiT), Beneyam Haile (AAIT), Ephrem Bekele (AAiT),
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As per the present switched system theorem, data package-drop ratio decides the strength of NCSs. Through the focal point principle to offer small data package-drop ratio for dispersed networked control systems (NCSs) under parameter transmission environment, the communication improvement issue is described from global transmission aspect. Initially, system stimulated break is illustrated as time-correlative function by auto-regressive-moving-average (ARMA) pattern, and the upcoming break is forecasted by the obtained break samples. Subsequently, the widespread referred shortest-route-of-time-dependent-network(SPTDN) algorithm is described and enhanced by means of introducing waiting-time previous to data packages are dispatched to subsequent unit in a route, in order to get earlier coming time than SPTDN. Subsequently, the concept of earliest-arrival time (EAT) is suggested to calculate the excellence of transmission route, the connected EAT algorithm is intended to look for upcoming EAT and the equivalent route from the global system vigorously. Advantage from the active EAT route, data packages reach at target as early as feasible, it reduces data package-drop ratio. Therefore, EAT route make sure the steadiness of shared NCSs from the opinion of worldwide system. Atlast, the experiment demonstrates the strength and efficiency of the suggested method.
Authors: Sundarrajan Mohan (Arbaminch University), Dr.Arunkumar Rengasubbu (Arbaminch University), Anusuya R (arbaminch university), Abraham Mesfin Federe (Arbaminch University),
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This paper presents the design and performance enhancement of single element, 2x1, 4x1, 4x4, and 8x8 elements inset-feed rectangular MSPA arrays for 5G mobile applications. The performance enhancement is achieved by employing in-set-feed impedance matching techniques, quarter-wave impedance transformer, and optimization of the parameters of the antenna simultaneously. All the studied antenna structures are designed using FR-4 substrate with a dielectric constant value of 4.4, and a height of 0.244mm to operate at 28GHz. The performances of the proposed antennas are analyzed using CST-MW studio software. The simulation results show that directivity of the proposed single element, 2x1, 4x1, 4x4, and 8x8 inset-feed rectangular MSPA arrays are 7.41dBi, 9.451dBi, 11.2dBi, 15.80dBi, 19.31dBi; similarly, the bandwidths are 572MHz, 575MHz, 1394MHz, 332MHz and 368MHz respectively. Moreover, the radiation efficiency is more than 94.95% for one-dimensional antenna arrays and more than 79% for the two-dimensional antenna arrays. As compared to existing designs in literature, the proposed antennas show significantly improved performance.
Authors: MULUGETA TEGEGN,
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Cardiovascular (CV) disorder is one of the critical health problem that cause economical and social impacts, even death to lots of peoples globally. Electrocardiogram (ECG) signal is the signal taken from the human body to study the status of CV and heart conditions. Before the introduction of computers, those tasks were done by the experts that cause various mistakes. Currently, the use of advancing signal processing devices manage to reduce these effects. Besides, it allows to develop various signal detection and parameter estimation algorithms. By studying the parameters of ECG signals, it is possible to determine whether the person is in critical condition or not. This helps to take an appropriate action. Various methods can be used to study and characterize the essential properties and parameters of CV signals. In this work, we study and analyze the state of the art on ECG based CV parameters estimation. We evaluate the performance of both classical and machine learning algorithms for parameter estimation. Besides we proposed an algorithm that combines adaptive Kalman filter (AKF) and discrete wavelet transform (DWT). In the proposed algorithm, the ECG signal is filtered using AKF. Then segmentation is performed and features are extracted using DWT algorithm. Numerical simulation is done to validate their performances. The results show that the proposed algorithm gives better performance than Kalman filter and has nearly the same performance with machine learning method.
Authors: Hiwot Birhanu Tazebew (Bahir Dar University), Amare Kassaw Yimer (Bahir Dar University),
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Now a days, many researchers are focussing on renewable energy sources to decrease or limit environmental effects. Wind energy is one of the fastest growing up energy source due to its cost effectiveness. In this paper, direct adaptive fuzzy proportional integral strategy for a maximum power point tracking (MPPT) control of variable speed wind turbine is proposed. Among different techniques of MPPT, tip speed ratio is proposed here. The basic idea of the proposed MPPT technique is to retrieve the optimal generator reference speed for any value of the wind speed. A 1.5 MW permanent magnet synchronous generator (PMSG) is selected for wind turbine due to its self-excitation property which allows operation at high power factor and efficiency. The effectiveness of the proposed system is tested through MATLAB/Simulink. The outcomes of the system through the proposed system are compared to the results of the system by conventional controller and shows better result.
Authors: Abrham Kassie (Debre Tabor University, Debre Tabor, Ethiopia, abrham2048@gmail.com), Endalew Haile (Addis Ababa Science and Technology University, Addis Ababa, Ethiopia, end_enday@yahoo.com), Venkata Lakshmi Narayana K (Addis Ababa Science and Technology University, Addis Ababa, Ethiopia, kvlnarayana@yahoo.co.in),
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This paper describes application of type-3 compensated error amplifier for switch-mode dc-dc converter using OrCad/Pspice simulation tool. For several decades power supply design has been showing a gradual movement away from the use of linear power supplies to the more practical switched mode power supply. The linear power supply contains a mains transformer and a dissipative series regulator that increase the size extremely and heavy 50/60 Hz transformers, and also very poor power conversion efficiencies approximated below 50%. These drawbacks are improved using switch mode power supplies that incorporates fast switching devices having estimated efficiency of above 80%, compact size and light in weight. These features are mainly due to the controller as a basic building block apart from the Dc-Dc converter, which is the heart of switch mode Dc power supply. Thus, in this paper application of type-3 compensated error amplifier for switch-mode dc-dc converter has been proposed and implemented using OrCAD/Pspice tool. Accordingly, dynamic and steady-state performance/evaluations have been performed for step changes input/output (load) side. The results revealed that the system has fast dynamic response and reduced steady-state error for input and output side disturbances.
Authors: Tefera T Yetayew (Adama Science and Technology Universty),
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In this paper, trajectory tracking control of quadrotor Unmanned Aerial Vehicle (UAV) is done by controlling attitude and position of the quadrotor using Sliding Mode Controller (SMC) including the effect of disturbances. Quadrotor UAV have been an increasingly popular research topic in recent years due to their low cost, maneuverability, simplicity of structure, ability to hover, vertical take-off and landing (VTOL) capacity and ability to perform variety of tasks. Dynamic modeling of the quadrotor was derived using Newton-Euler formalization including aerodynamic effects. Here SMC controllers were designed for the nonlinear model to track reference trajectories. The controller robustness are tested by adding external random disturbance on the position and attitude of the quadrotor. Finally, the behavior of the quadrotor under the proposed control system was validated or implemented by using MATLAB/Simulink. The results show that all control system becomes stable and robust in terms of disturbance rejection.
Authors: Biruk Nadew (Addis Ababa Science and Technology University), Asrat Mulatu Beyene (Addis Ababa Science and Technology University), Beza Nekatibeb (College of Electrical and Mechanical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia), Mulugeta Teji (Addis Ababa Science and Technology University),
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Nowadays, power systems especially distribution networks often operate close to their stability limit due to the rapid growth of new customers and inauguration of industrial sectors. Though the advancement of renewable energy sources (RESs) and Flexible Alternating Current Transmission (FACT) devices are the best solu-tions to meet these demands, they increase the complexity and dynamic behavior of the network. To solve these problems, the best option is to introduce advanced controllers that are fast, accurate and have a reliable synchronization method. Within this context, the Phasor Measurement Units (PMU) device is one of the most promising technologies which compose the backbone of wide-area and local monitoring systems in real-time. Thus, in this paper, the synchrophasor estimation (SE) algorithm which is the main component to build up a PMU, to estimate the phasor parameters (amplitude, phase, and frequency) is developed using iterative interpolated DFT technique. Even if the analyzed interferences are two harmonics (3rd and 5th), the developed algorithm can work for any type and number of inter-ferences. The simulation result shows that the algorithm can estimate the ampli-tude, phase, and frequency within the maximum error of 0.039, 0.002 and 0.0001 respectively. This research work can solve various interrelated problems of electrical utilities for those lack of a tool that able to trace the system at proper time snapshot like in our country Ethiopia.
Authors: Kassaye Eshetie (Bahir Dar Institute of Technology), Alganesh Teferi (Bahir Dar Institute of Technology), Belachew Gessesse (Bahir Dar Institute of Technology), Habtemariam Kefale (Bahir Dar Institute of Technology),
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The direct current from excitation system sustains stator and rotor magnetically coupled by spawning reactive power in the generator. Though, any excitation system failure grades generator loss of excitation and suspends power transmis-sion from generating unit to the grid. This paper presents a new excitation loss protection scheme based on study of field voltage, quadrature axis voltage and re-active power under specified system voltage. The proposed algorithm limits the reactive power consumption of the faulted generator to the ability of system to feed faulted generator without system loss of stability. IEEE 9 bus system is used to study the proposed approach on various excitation loss events. And the results showed that the new algorithm not only overwhelmed mal-operation of excitation loss relay, but also detects all possible excitation failures without system collapse in a short period of time.
Authors: Alganesh Teferi (Bahir Dar Institute of Technology), Habtemariam Kefale (Bahir Dar Institute of Technology), Kassaye Eshetie (Bahir Dar Institute of Technology), Belachew Gessesse (Bahir Dar Institute of Technology),
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The primary challenge in choosing the right electrification approach for any region is understanding the local energy resource potential. In this paper, estimation of solar resource potential in East Gojjam (EG) Zone, Ethiopia is presented. The solar insolation at four meteorological stations of EG is estimated from sunshine hour and extraterrestrial radiation. The sunshine hour data which covered a period of eleven years has been collected from National Meteorological Agency Bahir Dar Branch. This data is prepared and used to estimate the solar insolation using linear Ångestrӧm-Prescott (A-P) model. Site-specific A-P model is adopted by using regression coefficients, ‘a’ and ‘b’, which are obtained from empirical formulas. These empirical formulas are validated using the measured data from other meteorological sites in the region. The annual mean values of ‘a’ and ‘b’ for East Gojjam are found to be both 0.37. The annual mean daily solar insolation for Debre Markos, Debrewerq, Mota and Yetnora is estimated to be 5.47, 7.05, 6.11 and 6.16 kWh/m2, respectively, and 6.20kWh/m2 for EG. EG receives the highest and lowest solar insolation in April and July, respectively. The solar insolation profile at Debre Markos demonstrates a significant variability while Debrewerq receives more uniform solar radiation throughout the year; and therefore, the later site is the most suitable of all for solar energy investments with a highest and more uniform insolation throughout the year.
Authors: Engidaw Abel Hailu, Amache Godebo (School of Electrical and Computer Engineering, Debre Markos University, Debre Markos, EthiopiA), Ghantasala Rao (Debre Markos University), Takele Agajie (Debre Markos University), Yayehyirad Awoke (Debre Markos University), Ayodeji Salau (Afe Babalola University), Tesfaye Anteneh (Debre Markos University),
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Operating the photovoltaic (PV) system at/near Maximum power point is an imperative task of a maximum power point tracking (MPPT) technique. Available MPPT techniques can be classified as classical and modern optimization techniques. Among classical techniques perturb and observe (P&O) and incremental conductance (InCond) with duty ratio control are widely used due to relatively accurate MPP tracking capability and less implementation complexity under uniform radiation. However; steady-state oscillation, wrong perturbation direction for rapid climate change and failure to track the global peak under partial shade/mismatching operating conditions of the PV system are some of the drawbacks of these techniques. In this paper, a succinct review, formulations and evaluations of widely used classical techniques along with a proposed classical improved P&O to improve drawbacks of steady state oscillation has been done. The performance evaluation results of widely used classical techniques of P&O, InCond and the proposed improved P&O using MATLAB/Simulink revealed improved performances of the proposed algorithm over the existing classical P&O algorithm in reducing steady-state oscillations under uniform solar radiation conditions of the PV system.
Authors: Tefera T Yetayew (Adama Science and Technology Universty),
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Abstract-This paper presents the control scheme Modeling and analysis of three phase voltage switching inverter in using Space vector Pulse Width Modulation (SVPWM) technique for induction motor driven three-wheel electric vehicles. Induction motors are now widely applied in electric vehicle industries as the replacement of internal combustion engine due to the over striking price and environmental concerns. Performance of speed, direction and torque control for three wheel electric drives (Bajaj) has been studied. Better dc utilization for medium performance drive system, more efficient use of DC supply voltage, produce less ripples makes space vector pulse width modulation technique a good choice for this work. By keeping the ratio of stator voltage to frequency constant, this system tips can adjust the speed of the motor by control the frequency and amplitude of the stator voltage. Transfer model of induction motor, vehicle dynamic model and voltage source inverter type SVPWM model are designed and simulated using matlab Simulink. Control scheme visual realization has been done though Protues and Arduino IDE software. To demonstrate good performance of SVPWM based induction motor for three wheel drive, parameters such has stator current, rotor current, torque and speed as well as switching patter of the inverter waveforms have been displayed and analyzed.
Authors: Tewodros Gera, Assefa Egziabher (Adama science and Technology University), Tefera T Yetayew (Adama Science and Technology Universty),
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. In this paper Particle Swarm Optimization (PSO) based simultaneous distribution net-work reconfiguration and optimal Distributed Generation (DG) integration is conducted to significantly minimize the power losses and enhance the voltage profile of an electric power distribution network. The resource feasibility of solar and wind energy in Bahir Dar town was also assessed and the results revealed that solar energy production is more preferable. Backward/forward load flow analysis is deployed so as to determine the pow-er losses and the voltage profile of each buses in the system. The proposed method is tested using MATLAB software in one of Bahir Dar distribution feeders called Bata feeder, and the objective function is evaluated by considering numerous constraints such as radiality, voltage profile, DG output limit and branch current limit. The simulation results obtained using simultaneous distribution network reconfiguration and DG inser-tion are encouraging. The voltage magnitude of all nodes is above the minimum threshold value and the minimum voltage is enhanced from 0.9150pu to 0.9600pu. In addition to this, the active and reactive power loss reduction are 54.42% and 46.37%, respectively. The cost effectiveness of the required DG size is also scrutinized and the payback period has become five years.
Authors: Habtemariam Aberie (Bahir Dar Institute of Technology), Kassaye Gizaw (Bahir Dar Institute of Technology), Belachew Bantiyrga (Bahir Dar Institute of Technology), Alganesh Ygzaw (Bahir Dar Institute of Technology),
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This paper is aimed to statistically estimate wind power that can be converted to electrical power. It is important to have an inclusive fact of wind phenomenon to efficiently plan generation of power from the wind. To estimate wind power potential, this paper includes daily average wind speeds, monthly average wind speeds, and related wind power density, and frequency distribution based on wind speed probability frequency, Weibull and Rayleigh distributions. The two parameters for Weibull distribution were found out using data from the Adama wind farm site. The yearly average wind power densities for wind velocity frequency distribution, the Weibull distribution, and the Rayleigh distribution models 412W/m2, 370W/m2 and 532W/m2 respectively were estimated using wind speed statistics of the 2018 year at the ADAMA wind farm site. The result of this study shows that the selected site has utility-scale potential wind power.
Authors: Endalew Ayenew (College of Electrical and Mechanical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia),
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this paper presents Security Constrained Economic Dispatch (SCED) of renewable energy systems (RES). Reformulation of SCED for RES comprising biomass, large and micro-hydro plants, solar PV, solar thermal, waste to energy plant, wind farm and geothermal has been carried out. This enables RES prime-moved power systems provide secure and reliable service. Each of these sources requires problem formulation and constraint handling mechanism that take into account security limits and credible contingencies. Modified IEEE 118 bus system (NREL-118 test system), Ethiopian renewable energy system, and modified New England 39-bus system with high RES penetration features were used as case studies. Modeling and simulation was conducted on MATLAB, MATLAB/MATPOER, and DIGSILENT power factory simulation platforms. According to the simulation results obtained, it is deduced that the economic dispatch of RES is a promising step in connection to developments needed in the adoption and realization of smarter grids.
Authors: Shewit Tsegaye (Jimma University), Fekadu Shewarega (University of Duisburg-Essen), Getachew Bekele (Addis Ababa University),
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Fog computing is an extension of cloud computing where services are provided at the edge of a network. With the growth of the Internet of Things (IoTs) different applications are emerging. Many of these applications are delay sensitive that need high reliability. Different task scheduling algorithms are proposed to manage such applications under fog computing environments. Still, it is difficult to meet the required latency requirements of applications with existing algorithms. Therefore, in this paper, a delay sensitive data offloading algorithm is proposed that considers three different criteria during scheduling – the expected deadline of a given task and the computational capability of nodes. The effectiveness of the proposed algorithm is evaluated; first, by comparing the results obtained with existing task offloading algorithms, and second, by using two typical working scenarios of fog nodes. The overall result shows that the proposed algorithm can provide up to 70% improvement in the average response times of tasks of IoT applications.
Authors: Asrat Mulatu Beyene (Addis Ababa Science and Technology University),
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The insurance industry has been factually a growing industry.Fraud in workmen’s compensation insurance is done by intentional deception or misrepresentation for gaining some benefit in the form of health expenditures.Handling fraud manually has always been costly for insurance companies. This study is initiated with the aim of demystifying predictive analytics with DM techniques in developing models that can detect and predict fraud suspicious insurance claims with a particular emphasis on EIC in the case of WC. The research has applied the clustering algorithm followed by classification techniques for developing the predictive model. Predictive analytics is used to build analytical models that use past data (where outcome variable is known) to build a model, which can predict the value of the outcome variable in new data where outcome variable is not known, and it helps to decision making. K-Means clustering algorithm is employed to find the natural grouping of the insurance claims as fraud and non-fraud. The resulting cluster is then used for developing the classification model. The classification task is using the J48 decision tree and JRip rule algorithm in order to create the model of classifying fraud suspicious claims. An ensemble method is to improve the performance of the classifier, particularly the Adaboost method JRip as a base classifier scored an accuracy of 98.26% on 80% split. CLAIM_REPORT _LENGTH_ DATE is the determinant factor for predict fraud suspicious
Authors: Betelhem Zewdu (Wachemo University), Gebeyehu Belay (Bahir Dar University),
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Open Information Extraction (OIE) is the process of discovering domain-independent relations from natural language text. It has recently received increased attention and was applied extensively to various downstream applications, such as text summarization, question answering, and informational retrieval. Although a lot of OIE systems have been developed for various natural language text, no research has been conducted in Amharic OIE yet. In this paper, we present AOIE, an Open Information Extraction for Amharic language, which implements hand-crafted rules working on simplified and shallow parsed sentences. The system comprises of a preprocessor for POS tagging, sentence cleaning and morphologically analyzing the input text, a phrasal chunker which divides the input sentence into non-overlapping phrases, a sentence simplifier for segmenting each sentence into a number of self-contained simple sentences that are easier to process, the relation extractor which extracts relations from simplified sentences and finally the post-processor prints extracted relations in N-ary format. The system was evaluated with a dataset from different domains. Test results show that AOIE achieves 0.88 precision and 0.64 recall. The result of the evaluation shows the complexity of sentences and the accuracy of parsing techniques has a significant impact on the accuracy of AOIE.
Authors: Seble Girma, Yaregal Assabie (Addis Ababa University),
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Amharic is the official language of Ethiopia. It is the second-most commonly spoken Semitic language in the world next to Arabic. Amharic is morphologically complex and under-resourced, which poses tremendous challenges for natural language processing. The development of fully functional Amharic text processing applications is a non-trivial task for researchers and developers. Despite attempts to develop some applications, lack of standards in corpus collection and resource development resulted in the problem of interoperability. The aim of this paper is to present and evaluate accessible Amharic corpora, resources and tools with the purpose of highlighting the status of Amharic language processing applications. We present available resources and linguistic tools, assess their usability and effectiveness, investigate the implications of the morphological complexity and put the way forward in the development of Amharic text processing applications.
Authors: Tilahun Yeshambel (IT Doctoral Program ,IR Track,Addis Ababa University), Josiane Mothe (INSPE, Univ. de Toulouse Institut de Recherche en Informatique de Toulouse, UMR5505 CNRS), Yaregal Assabie (Associate Professor of Computer Science , Associate Dean for Research and Technology Transfer College of Natural and Computational Sciences, Addis Ababa University),
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Main challenge in the technology of image processing is designing of efficient technique for a suitable application area, because the technology is application dependent. Therefore, great attention must be given to designing of the efficient technique and utilizing of the efficient one for the right application. The main aim of this paper is proposed to design efficient image processing techniques by applying Canny edge detection method for extraction of edges. Next, Hough Transform (HT) for getting strong and thin lines from extracted edges. Eventually, orthogonality checking for corner detection and cropped corner parts of image for similarity matching to detect solid waste bin (SWB). To detect corner of the image correctly, two orthogonal lines whose length and coordinate points are thoroughly considered. These orthogonal lines are extracted from detected corners. 20-by-20pixel width of the detected corner part is cropped. Similarity matching of template image with original image by using cross correlation is done for the correctly detected corner part of the images. Eventually, performance evaluation of the designed technique with existing techniques is done which shows the proposed technique is efficient in detection of SWB.
Authors: Bereket Simon (Wolkite University),
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One of the major forms of pre-processing in information retrieval and many other text processing applications is filtering out stopwords. They are ignored by many retrieval systems during indexing and retrieval in order to enhance retrieval effectiveness and efficiency. Although stopword lists have been constructed for many languages, there is no standard stopword list for Amharic. Therefore, the aim of this paper was to present the construction of morpheme-based Amharic stopwords and investigate their effect on Information Retrieval (IR) tasks. The stopword list is constructed based on semantics of Amharic words and corpus statistics such as frequency, variance, entropy and mean parameters. The stopword list is evaluated using Lemur on Amharic IR test collection. Removal of stopwords has shown significant impacts on retrieval effectiveness, size of index, and term weighting of non-stopwords. Their presence in index and query affects the retrieval effectiveness of Amharic retrieval system. The average precisions of retrieving with and without stopwords using language modeling (LM) on root based approach are 0.24 and 0.70 respectively.
Authors: Tilahun Yeshambel (IT Doctoral Program ,IR Track,Addis Ababa University), Mothe Josiane (NSPE, University of Toulouse, IT Research Institute, UMR5505 CNRS), Yaregal Assabie (Associate Professor of Computer Science Associate Dean for Research and Technology Transfer , College of Natural and Computational Sciences, Addis Ababa University),
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The coronavirus pandemic caused a radical change in everyone's life, the number of infected persons increases each day, in some hospitals in Mexico, especially in rural areas, artificial respirators are not available to treat this disease, since they are costly devices high. This article presents a ventilator alternative controlled and monitored by an Internet of Things platform, which has three au-tomatic modes of operation with certain frequencies, which are for children, ad-olescents and adults. In addition, a manual configuration was added to modify the frequency from the operating system. The structure of the ventilator has a cam system that allows the pressure to be changed in a medical resuscitator AMBU, modifying the level of oxygen that can be supplied to a patient. To move the cam system, an axle was placed which is powered by a gear system connected to a recycled wiper motor.
Authors: Fabián García Vázquez (Posgrado en ingeniería y tecnología aplicada, Unidad Académica de Ingeniería, Universidad Autónoma de Zacatecas, Ramón López Velarde 801, C.P. 98000, Zacatecas, Zacatecas, México.), Héctor Alonso Guerrero Osuna (Posgrado en ingeniería y tecnología aplicada, Unidad Académica de Ingeniería, Universidad Autónoma de Zacatecas, Ramón López Velarde 801, C.P. 98000, Zacatecas, Zacatecas, México), José Manuel Ortiz Rodríguez (Posgrado en ingeniería y tecnología aplicada, Unidad Académica de Ingeniería, Universidad Autónoma de Zacatecas, Ramón López Velarde 801, C.P. 98000, Zacatecas, Zacatecas, México), Ma. Del Rosario Martínez Blanco (Posgrado en ingeniería y tecnología aplicada, Unidad Académica de Ingeniería, Universidad Autónoma de Zacatecas, Ramón López Velarde 801, C.P. 98000, Zacatecas, Zacatecas, México.), Antonio del Rio-De Santiago (Posgrado en ingeniería y tecnología aplicada, Unidad Académica de Ingeniería, Universidad Autónoma de Zacatecas, Ramón López Velarde 801, C.P. 98000, Zacatecas, Zacatecas, México),
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The increase in large scale data available from different sources and the user’s need access to information retrieval becomes more popular these days. The way of providing the queries and the system responds to relevant results for the users should be improved by expanding the original queries from semantic lexical resources that are constructed automatically from a text corpus using neural word embedding. In this study, we propose Amharic information retrieval using semantic vocabulary. After the embedding is implemented using Word2Vec, the semantic vocabulary is constructed using cosine distance. We believe providing lexical resources is much essential for the users as well as for the NLP communities. After constructing the resource, we have integrated it with the information retrieval system and the user’s query is expanded from the semantic vocabulary which could enhance the retrieval relevancy. The semantic vocabulary based on the word analog prediction using the cosine metric is promising. It is also compared against the semantic thesaurus constructed with the latent semantic analysis (LSA) and it increases by 17.2% accuracy. Information retrieval using semantic vocabulary based on ranked retrieval increases by 24.3% recall, and using an unranked set of retrieval, 10.89% recall improvement was obtained.
Authors: Berihun Getnet (Wolkite University), Yaregal Assabie (Addis Ababa University),
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To foster an agile process of learning of students by value-based Scrum is the motivation of the author as researcher and practitioner in both software engi-neering and education. This article describes the Framework valuable Scrum Learning Process Coaching, which enables the development and implementa-tion of self-effective learning arrangements for an agile mindset of students. The research showed that there is a huge amount of articles describing the use of scrum teaching Software Engineering establishing a virtual or real capstone project, but there are some open research questions. It appears to be relevant to find out what are the impacts of successful supporting, what has a positive ef-fect on the learning result of participants in value-based scrum. In order to an-swer the questions an experimental study was conducted with students in Ger-man higher education (N=78). Considering the students´ point-of-view, the di-dactical approach allows to improve their own learning process reflecting the learning cycle: Plan, Do, Check and Learn. With this sustainable didactical ap-proach, it is possible to research the impacts of using value-based Scrum as a framework of agile teaching and learning. The results show that groups with dedicated values benefit from their intensive teamwork.
Authors: Martina Mueller-Amthor (University of Applied Sciences Kempten), Georg Hagel (University of Applied Sciences Kempten),
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This paper deals with the characteristics of performance of Artificial Im-mune Network System (AINS) for practical application. Research builds immune based control model for pendulum with nonlinear characteristic and compare its characteristics with GA. AINS always has a new parallel decentralized processing mechanism for various situations by using the an-tibody communication function. Antibody has huge communication sys-tem function among different species of antibodies B-cells through the stimulation and suppression chains among antibodies that form a large-scaled network. In addition to that, the structure of the network is not fixed, but varies continuously. That is, AISN has a flexibly self-organizes accord-ing to dynamic changes of external situation. From the above facts, this pa-per studies performance of controller of ANIS and compare its control func-tion with GA.
Authors: Dong Hwa Kim (ASTU), T Tefera (ASTU), Hee Won (Wonkwang Uni),
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Abstract: Disposal of wastes resulting from myriads of human activities continues to be a problem especially in developing nations like Ethiopia, where effective and efficient wastes disposal system is lacking. Animal bone ash, being rich in calcium content, enhances binding property of cementitious substances and has potential to partially replace cement in concrete production. This study aims at investigating behavior of concrete produced with cement being partially replaced with bone ash at elevated temperatures. The effect of intensity of elevated temperature (300, 600 and 9000C), duration of temperature exposure (1hr.and 3hr.), cooling methods and various bone ash cement blending percentages (0%, 5%, 10%, 15% and 20%) are investigated. To this end, a total of 237 concrete cylindrical test specimens were casted and tested to explore behavior of concrete with cement replaced with bone ash at elevated temperatures. Test results indicate that weight, compressive and tensile strengths of bone ash blended cement concrete reduce with an increase in temperature and their respective test values depends on choice of cooling methods. Fast cooling results in an additional strength loss of 35% as compared to natural air cooling. Also, residual compressive strength of concrete decreases sharply beyond 10% replacement of cement with bone ash. This implies optimum threshold value of bone ash replacement of cement in concrete at elevated temperature is 10%.
Authors: Solomon Anteneh (Department of Civil Engineering, Institute of Technology, University of Gondar, Ethiopia), Tesfaye Mohammed (Civil Engineering Department, Addis Ababa Science and Technology, Ethiopia),
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Rock bolts and concrete lining are usually provided to support excavated tunnels on different ground conditions. These two support systems are worthy and need in-depth consideration as their impact on tunnel cost and deformation are critical. Thus, the optimum use of these support systems are a challenge that demands the best design solution. In this study, in order to facilitate the determination of the optimal combination of the two, an optimization scheme has been devised using Finite Element Analysis (FEA) and MATLAB for a specific under-construction tunnel in Karakore, Ethiopia. The tunnel displacements found from the FEA and the cost of tunnel construction are modeled using polynomial functions. Since the problem has two objectives, a multi objective optimization is executed. Considering displacement and cost functions, the optimum combination of rock bolt and concrete lining has been found. The result shows that the optimum combination can be found by increasing the number of rock bolts. The finite element analysis result of optimized design combination gives a total displacement of 6.34 cm at the best scenario case. But the observed total displacement inside the tunnel was about 6 cm which is less than the predicted displacement of optimum combination using numerical analysis. The total cost of rock bolt & concrete lining for the optimum combination become $30,700 per 34 m2 of tunnel rock bolt and concrete lining construction.
Authors: Sinodos Sefene (Debre Markos University), Henok Gebregziabher (Addis Ababa Institute of Technology),
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Two dams have been constructed on Ribb and Megech Rivers, in Tana Sub basin, Ethiopia. The dams and appurtenant structures have been designed by same designer, both dams have similar foundation, capacity and profile. However, Ribb dam spillway was designed and constructed with drainage blanket beneath the spillway channel slab. Whereas, the design and construction of Megech Dam Spillway was without this material. This study investigates the distribution of uplift pressure and seepage at control, chute and terminal section of the spillways foundation of Megech and Ribb dam projects with and without drainage blanket using SEEP/W software and measured data. The result showed that on Ribb dam spillway up to 14% reduction of uplift pressure around control section and an average of 5% uplift pressure reduction at chute section of the spillway was found by using drainage blanket beneath the structure. If this drainage sand has been used on Megech dam spillway up to 12% uplift reduction around control section and an average of 3% reduction can be achieved at chute section of the spillway. Therefore, the provided drainage blanket beneath the spillway channel slab at control and chute section of Ribb dam spillway is necessary and good design. Whereas, the design and construction of control and chute section of Megech dam spillway without drainage blanket beneath channel slab is not safe against uplift pressure.
Authors: Yirga Anteneh (Ethiopian), Mengiste Meshesha (Ethiopian),
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There are few pressurized irrigation projects launched in Ethiopia. Yet, there are no more research works on the performance evaluation of pressurized irrigation systems. So to fill this gap, this study was conducted on performance evaluation of Hormat Golina– 4 drip irrigation systems in Kobo Girana Valley. The objective of the study was to evaluate the hydraulic and operational performance of Kobo Girana pressurized irrigation system. The emitter discharge and soil mois-ture content were collected from seven experimental plots. The emitter flow was collected by using a total of 63 catch cans, 9 catch can per plot area and measured by using graduated cylinder. Hydraulic performance indicators such as application efficiency (Ea), irrigation adequacy (Pa), equity performance (PE), dependability performance (PD), delivery performance ratio (DPR) and distribution uniformity characteristics; percentage of completely clogged emitters (Pclog), emis-sion uniformity (EU), emitter flow rate variation due to emitter performance in the field (qvar), coefficient of variation (Cv) and coefficient of uniformity (Uc) were evaluated accordingly. The average values of the above discussed parameters in the scheme were found that Ea (61.41%), Pa (41.52%), PE (0.33), PD (0.23), DPR (2.21), Pclog (33.33%), EU (47.71%), pvar (71.03%), CV (45.31%) and UC (53.42%), respectively. Results showed that the overall performance level of Hormat Golina – 4 drip irrigation systems is low and poor.
Authors: Kassa Abera,
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Water and energy are so versatile that play great role in fulfilling the daily requirements of human life. Having knowledge on the future water and energy demand of the world as a whole, a country, a region and even a single city/town helps for planning and establishing water and energy policies. Regression model was used to estimate the energy and water demand considering the socio-economic drivers as parameters. Urban population growth rate is around 5.2% due to the rapid population growth rate of the commute. As different studies show, the low GDP growth rate of Addis Ababa is roughly 11%. Average population and GDP/capita based scenario was used to predict the residential, commercial and industrial energy demands. Population and GDP/capita based scenario was used to predicts the transport (street-lighting) energy demand. The total electricity energy demand for residential, commercial, industrial sectors and street-lighting was around 50 and 190 Peta Joule in 2030 and 2050 respectively. The energy requirement for water distribution, transmission and water treatment was determined. Population and GDP scenario based residential, commercial and in-dustrial was used for the estimation of water demand. Hence, the total water demand of the city was predicted to be 0.4 and 0.68 billion cubic meters in 2030 and 2050 respectively.
Authors: Bedassa Kitessa, Semu Moges (University of Connecticut, School of Civil and Environmental Engineering), Geremew Gebrie (Addis Ababa Institutes of Technology, Addis Ababa University-School of Civil and Environmental Engineering, P.O.Box 385), Solomon Teferi (Addis Ababa Institutes of Technology, Addis Ababa University, P.O.Box 385),
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This study tried to investigate trends and variabilities in mean and extreme hydro-climatic varia-bles in Wabi Shebele river basin. Linear trend investigation, Mann-kendall trend significance test and quantile perturbation method (QPM) are used in the study. The result indicates that less in-creasing trend in mean annual flow in the basin up to 0.58Mm^3/year, 1.49Mm^3/year, 0.94Mm^3/year and 11.06Mm^3 in Maribo, Wabi at Dodola, Robe and Erer river flows respec-tively. Similarly, less increasing trend is observed in annual rainfall in western-eastern upper basin whereas decreasing trend in middle-lower part of the basin around Robe, Gindhir, Degeha-bour and Gode area. Mean temperature shows significant increasing trend in upper and middle part of the basin, but decreasing trend in lower basin. The QPM analysis in flood and precipita-tion extremes indicates there is five/5/ year frequency of significant anomalies and general in-creasing trends in floods. In early 1980s, significant negative perturbation was observed in Mari-bo, Robe and Erer rivers. Whereas, positive significant perturbations are observed in Maribo, Wabi at Dodola, Robe and Erer watersheds between 1986-1989. The precipitation extreme anom-alies increase at Adaba station and decreasing trend at Robe (Arsi) station. The positive signifi-cant correlation between precipitation and flood discharge up to 65% R2 value is observed in dry season. The others statistical correlation values show, less than 50% in average.
Authors: Fraol Abebe (School of Civil and Environmental Engineering, Addis Ababa Institute of Technology (AAiT), Addis Ababa University, Ethiopia), Semu Moges (Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd, Storrs, CT 06269), Belete Berhanu (School of Civil and Environmental Engineering, Addis Ababa Institute of Technology (AAiT), Addis Ababa University, Ethiopia),
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Industrial Effluents are a major challenge to be treated and disposed of without contamination of water and soil. Soft drinks Industrial effluents are having alcoholic compounds which are toxic to aquatic life as well as the environment. In the past, the increasing demands for energy and impending climate change have driven the search for renewable energy sources. Diminishing supplies of fossil fuels and production of pollution are the major challenges with the continued use of fossil fuels. The aim of this paper was to give an account of biogas production from beverage, industrial effluents as well as effluent treatment for environmental safety. Besides, the study helped to compare the capacity of mixed substrates and pure beverage, industrial effluents to release methane gas. The anaerobic digestion removed 68.95%, 65.30% and 71.74% of BOD5, TS and VS, respectively from beverage industrial effluents. Mixed substrates comparatively produced more methane than beverage industrial effluents. Beverage industrial effluent released 323. 5ml of bio-methane with a cumulative CH4 yield of 76.15ml per gram of VS which was added into the reactor per working volume of 1.8L. Soft drink industry can establish a biogas plant to fulfill the energy needs of industry.
Authors: Reddythota Daniel, Atsede Tesfay (M.Sc Student, Faculty of Water Supply & Environmental Engineering, ArbaMinch Water Technology Institute, Arba Minch University, ArbaMinch, Ethiopia),
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In this paper we investigate the sizing and design of a standalone photovoltaic water pumping system in Ngoundiane, a village located in Senegal. We apply first an intuitive sizing method to get approximate information on the sizes of the various components. To improve the results, we elaborate a new sizing approach based on numerical methods using the Average Loss of Power Supply Probability (ALPSP) criterion. The comparison of the results showed that the numerical method proposed allow a reduction of the storage capacity when compared to the intuitive meth-od. However, we notice that the values of ALPSP are particularly high, probably due to the over-estimation of input parameters.
Authors: Senghane MBODJI (Alioune Diop University), Amy Sadio (Alioune Diop University), Biram DIENG (Alioune Diop University), Arona NDIAYE (Alioune Diop University), Ibrahaima FALL (Alioune Diop University), Papa Lat Tabara SOW (Alioune Diop University of Bambey),
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This paper deals on design and experimental test on solar powered evaporative cooling which maintain the inside temperature is lower than ambient temperature with higher relative humidity for storage of fresh agricultural products such as tomato, carrot and green chili (pepper) and it is compared with an ambient conditions by hourly in every day. The experimental setup is a rectangular shaped storage space made of galvanized steel for external cover, aluminum for internal cover insulated with fiber glass. Axial fan supplies 0.78 m3/s air at a speed of 0.93 m/s to wet pad and for recycling of water through copper tube, an axial pump having flow rate of 0.054 kg/s is used to remove the heat from the commodities. The results reveal that the shelf life of the vegetables is increased 12 days when compared with ambient conditions. The temperature range of the cooling cabinet is found 16.2 to 22.1°C during the hottest time of the day and the ambient temperature varied from 22.6 to 29.8°C. The relative humidity is found between 75 and 90 percent when the outside condition is recorded between 66 and 80 percent. The maximum weight loss found after the sixth day for carrot, tomato and pepper are 8, 10 and 16 percent in cabinet conditions and 50.6, 38 and 50 percent in ambient conditions respectively. The commodity decay is found in the ambient a condition is faster than that of the commodity stored in an evaporative cooling system. Evaporative cooling efficiency is found 82 percent.
Authors: Lijalem Abate (Faculty of Mechanical and Industrial Engineering, Bahir Dar Institute of Technology, Bahir Dar University), Dr. Bimrew Tamrat (Bahir Dar University), Raja Kathiravan (BiT, BDU),
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Human bodies are often exposed to vibrations when they are in the working place or vehicles.The low back pain and the degenerative diseases of the spine are more frequently found in humans exposed to vibration. In order to minimize these diseases, the occurrence of resonance conditions in the human spine body should be prevented; the determination of the natural frequency of each vertebra of the spine is the most required parameter to satisfy no occurrence of a resonant condition. This study aimed to determine the specific fundamental frequencies of the human spine vertebrae. In this paper, a detailed three-dimensional geometrical model of seated human spine vertebral is developed in Solidworks software based on actual vertebral geometry and the finite element model modal analysis is done by using ANSYS software. After FE modal analy-sis, the resonant frequencies of each vertebra of cervical (7), thoracic (12) and lumber (5) of the adult human spine are obtained and the fundamental frequencies of the vertebrae versus span of the spine are plotted. The result shows that the fundamental frequencies of all vertebra of the spine are different and the mini-mum fundamental frequency is 6.023 Hertz for the thoracic spine (T4). In addi-tion, it is revealed that for the whole spine vertebrae the fundamental frequency range is 6-19Hz. The spine resonant condition may occur at any of this frequency range even though the fundamental frequency of the spine is 6.023Hz.
Authors: Mekete Mulualem (Bahir Dar Institute of Technology),
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The Stirling cycle refrigerators, which are the counterparts of the Stirling engines are of gas cycle machines. The present research focuses on the simulation of numerical model of a Beta-type Stirling cycle refrigerator for domestic application especially to evaluate the effect of different working fluids. The simulation result of the model is validated using experiment. First, the developed model which is a modified simple analysis method is validated experimentally using the FEMTO 60 Stirling engine as a case study. The minimum no-load temperature achieved from experiment at a pressure of 25 bars and a frequency of 12.1Hz is -68.20C. The stabilization temperature is found after 20 minutes of operation. The input power required, cooling capacity, and COP of the refrigerating machine are evaluated for different fluid types(air, nitrogen, helium, and hydrogen) at different charge pressure and operating frequency. Better refrigeration performance is found for this Beta-type Stirling refrigerator in case of using nitrogen or air gas rather than using either helium or hydrogen. The maximum COP found for the existing configuration is 74.9% using nitrogen gas at hot heat exchanger temperature of 305 K, chiller temperature of 295K, charging pressure of 25 bar, and operating frequency of 8.5Hz.
Authors: Muluken GETIE (FEMTO-ST Institute, Univ. Bourgogne Franche-Comté, CNRS), François LANZETTA (FEMTO-ST Institute, Univ. Bourgogne Franche-Comté, CNRS), Sylvie BEGOT (FEMTO-ST Institute, Univ. Bourgogne Franche-Comté, CNRS), Bimrew ADMASSU (Bahir Dar Institute of Technology, Bahir Dar university, Bahir Dar, Ethiopia), Steve DJETEL GOTHE (FEMTO-ST Institute, Univ. Bourgogne Franche-Comté, CNRS),
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Damping capacity is the ability of materials which absorb vibration energy by converting into heat. Materials which have high damping capacity can suppressed excessive vibrations to a reasonable limit. Therefore, this paper investigates the damping characteristics of five indigenous wood species (Cordia Africana, Juniperus Procera, Afrocarpus Gracilior, Syzygium Guineense and Acacia Decurrens) found in Ethiopia through analytical, numerical and experimental approaches. The experimental testing was performed using piezoelectric accelerometer in association with LabVIEW for a perfectly clamped-free cantilever beam based on the impact hammer excitation. The damping ratio was computed using logarithmic decrement method from the decay curve measured. Based on the investigation, the damping factor for all species of woods was almost equal to 0.020 at room condition, and it is definitely greater than most other crystalline materials. Thus, wooden materials are better suitable for engineering applications in terms of vibrations if the other strength properties are satisfactory
Authors: Fasikaw Kibret (Kombolcha Institute of Technology), Dr Hailu Shimles Gebremedhen (Bahir Dar Institute of Technology),
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One of the most utilized materials in the construction sectors having enormous compressive strength but weak in tension is concrete. This weakness overcomes with addition of the steel reinforcing bars whose properties must comply stand-ards. Steel is an ideal material available at affordable cost to reinforce concrete as it has good ductility with high modulus of elasticity and same thermal expansion with concrete. The Ethiopian construction industry uses locally manufactured and imported rebar available from an open market. Locally produced reinforcing steel bars are milled from imported billets or local billets manufactured from scraps collected as obsolete products. Reinforcing bars produced from Ethiopian metal industries are selected next to the imported one without justifiable reasons. This paper dealt with evaluation of yield strength and ductility of rebar based on the compulsory Ethiopian standard to comply the quality of these locally manufac-tured rebar in order to build customers confidence. The Strength of four samples 14 mm diameter rebar three from locally produced and one the imported taken from the construction site were tested using universal testing machine. Addition-ally tension test data of different rebar collected from Amhara Design Supervi-sion and Consultancy Work Enterprise were analyzed. Based on the results ob-tained, some of reinforcing bars from imported and locally produced have faced rejection
Authors: Tefera Eniyew Fente (Bahir Dar University), Assefa Tsegaw (Bahir Dar Institute of Technology), Wim Dewulf (KU Leuven – University of Leuven, Department of Mechanical Engineering, Leuven, Belgium),
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Mathematical modeling of a unidirectional hybrid composite is performed using classical lamination theory. The effects of varying volume fractions of sisal and glass fibers on the mechanical properties of the hybrid composite are studied. Experimental results were obtained for seven samples of composite materials. Impact, tensile and three-point bending tests were performed for studying different characteristics of the hybrid composites. Variability in mechanical properties due to different volume fractions of the two fibers was studied. It is found that there was significant variability in tensile strength, flexural strength, and impact resistance properties of the hybrid composite materials due to the variation in volume fractions of sisal and glass fibers. Generally, the hybrid composite samples have better mechanical properties compared with pure sisal epoxy and glass-epoxy composite materials.
Authors: Abebe Zeleke, Dr Hailu Shimles Gebremedhen (Bahir Dar Institute of Technology),
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The main purpose of this study was analysis the effect of oil treatment of Ethiopian lowland bamboo on tensile and bending strength of bamboo. In this study Ethiopian lowland bamboo treated by oil in different treatment condition with hot oil and without hot oil. The treatment temperatures were 100, 130 and 160 degree centigrade with sun flower oil and treatment duration of 30,60 and 90 minutes and bamboo immersed in oil for 2, 4 and 6 days without heat. After oil treatment of bamboo tensile and three point bending experimental test were investigated for treated and untreated bamboo samples. The experimental result showed that from all condition of oil heat treatment best tensile results were bamboo treated at 100 degree centigrade with sun flower oil for a duration of 60 minutes and for bending bamboos treated at 160 degree centigrade for a duration of 30 minutes. In addition to this bamboo treated without hot oil for a duration of 2,4 and 6 days had good tensile and bending strength at long treatment duration.
Authors: Berhanu Mengstie (Ethiopia), Eden Addisu (Ethiopia),
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This research work focuses on design of improved class room chair for adult students to enhance active and conducive teaching learning environment in Ethiopia. The motivation to do this research is the observed challenges and functional requirements in the classroom of many Ethiopian higher education institutes. A well designed classroom chair is considered as an important teaching resource to improve comfort and concentration in lecturing and peer activities of students. After considering the challenges and functional requirements in class room, many conceptual nodal classroom chairs were sketched to reach to the final design of the class room chair that can meet the specified objectives. The designed nodal class room chair was developed based on the assigned criteria’s such us functionality, manufacturability, flexibility affordability etc. The designed chair has four pivots to move the seat and table on the specified position to allow interaction of students on any given task of the lecturer. It is also designed considering the international furniture design guide line to maintain the ergonomic and anthropometric size of higher education students. In the final design of nodal class room chair, the critical dimensions of average popliteal height of seat chair and table height are taken 46cm and 760cm respectively to reduce fatigue as per BS EN 1729 standard guide line.
Authors: Fetene Teshome (Bahir Dar Institute of Technology-Bahir Dar University), Eyob Messele (Bahir Dar Institute of Technology-Bahir Dar University),
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Porosity are an inherent characteristics of Powder metallurgy (PM) materials. The size, distribution and morphology of porous in the microstructure have negative effect on mechanical properties, to the resistance of impact, normal fatigue and contact fatigue damages it is more deterministic. The presence of larger size and irregular shape of the pore are statically the site for crack nucleation, and propagates through the cluster of porous. Modeling and measuring pore parameters are important to predict these behaviors and link with the mechanical properties. Pore modeling using a basic feature of square, rectangular and triangular geometries were proposed. Pore parameters, such as fcircle, fshape and equivalent diameters were analyzed using the model developed based on the proposed geometries of porous. Moreover, the pore parameters were measured directly on microstructures of pre-alloyed and diffusion bonded sintered steels using digital image analysis. The experimental results were in agreement with the model results. Larger rectangular geometric pore characterized by lower in circularity and elongated in shape.
Authors: Samuel Tesfaye Mekonone (Addis Ababa Institute of Technology), Solomon Mesfin Demlie (University of Gondar), Alberto Molinari (University of Trento),
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In this study, the free and forced vibration analysis of fiber reinforced plas-tic composite beam has been conducted using numerical method (finite el-ement analysis) and mathematical modeling in MATLAB. Mechanical and physical properties of the beam material are found using strength of material and semiempirical approach to get the equivalent properties. The beam is configured as cantilever beam with dimensions of 191 mm ×33 mm × 5.66 mm for all analyses of the vibration. For modal analysis of the vibrations, different effects such as fiber volume ratio, fiber materials, angle of orienta-tion and stacking sequence of laminates are studied. From these effects, stacking sequence of laminates have highest influence on variation of stiff-ness and natural frequencies with unique fiber volume ratio and same fiber material. Forced vibration analysis was carried out using the same beam configuration as modal analysis, but with different stacking sequence of layers with harmonically exited loads. It has been observed that the vibra-tion resonance occurred close to the natural frequencies of the beam.
Authors: Hirpa G. Lemu (University of Stavanger, Norway), Nigatu Tilahun (Addis Ababa Science and Technology University, Addis Ababa, Ethiopia),
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A hydraulic ram is a cyclic water pump powered by water hammer effect. The device uses to develop pressure permits a portion of water that powers pump to be elevated to a point higher than where the originally started. The ram is often useful, since it requires no outside source of power other than kinetic energy of flowing water. This paper deals with adaptation of water ram pump for small-scale irrigation. This research conducted making using of ANSYS, computational fluid dynamics. Different configurations of waste valves have been designed, checked and investigation results recorded. Investigations show that height testes effect on drive head, delivery head, pipe cross sections, design and arrangements of waste valve, flow rate and velocity. The final optimum ram pump has de-signed, developed and tested at ‘Woreb’ villages around Bahir Dar for small-scale irrigation and household purpose. It is observed that at a river flow rate of 9L/min and head of 5 meters, hydraulic ram pumps water at a flow rate of 0.7L/min for 37M head. This typical test shows raising of water up to 740% with respect to height can be achievable. Moreover, this pump can extensively be uti-lized in rural areas where water is flowing in gorge areas for 7/24 at no expense of extra power utilized.
Authors: Assefa Asmare Tsegaw (Bahir Dar University),
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By this study, there is an effort to investigate the practice and method of nature-inspired design. Engineering design enhancement that achieved by natural phenomena mimicking and adapting it to develop new products is the designers' initiative as cost-effective design methods. The use of spider web geometry practice and trends as a technique for orienting fiber to reinforce composite was reviewed rigorously in this paper. An Orb web possesses many unique features to be mimicked for engineering structure. Spider web develops a self-stressing nature, which offers its excellent inelasticity and provides webs a mechanism for competent and economical means for harmonizing the local and global induced stresses in the structure. These make a spider web a model of engineering material with exceptional properties of combining a unique strength and toughness. Since the mechanical property of the fiber-reinforced composite intensely swayed by fiber orientation. Spider web-oriented types of fiber orientation not yet used for the engineered composite product except for cable-stayed bridges load suspension. Lastly, a significant research gap between engineering design cognition and natural phenomena identified for forthcoming researchers. Concluding remark on natural emulating design practice was lightened.
Authors: YOHANNES DHUGA (Addis Ababa Science and Technology University), Belete Yigezu (Addis Ababa Science and Technology University), Hirpa G. Lemu (University of Stavanger, Norway),
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The intent of the study reported in this paper is to make analysis of the wind speed data and annual wind energy potential at Abomsa Metehara and Ziway in Ethiopia. The wind speed data was collected from National Me-trology Agency of Ethiopia, and then monthly and annual mean wind speed, wind power potential, wind energy potential and Weibull distribu-tion parameters for these three sites have been analyzed and assessed. In the results, the monthly mean wind speeds, the measured and Weibull estimat-ed of most probable monthly wind velocity, wind velocity carrying maxi-mum energy, monthly wind power and wind energy density for these three sites at site locations have been estimated. Based on monthly and annually mean wind speeds at stations, annually and monthly mean wind velocities at 40 m, 60 m, 80 m, 100 m and 120 m heights via wind shear law have been extrapolated. At these heights, annual mean wind velocity carrying maxi-mum energy, annual most probable wind velocity, annual mean wind power and annual wind energy density for these sites have been estimated. Addi-tionally, the annual cumulative distribution function and probability den-sity function of wind speed for the selected sites have been obtained using the Weibull distribution functions.
Authors: abdulbasit Mohammed (Addis Ababa Science and Technology University), Hirpa G. Lemu (University of Stavanger, Norway), Belete Sirahbizu (Addis Ababa Science and Technology University),
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Strategic production configuration in developing economies requires verified knowledge of the production system and its environment. In order to model these reproducibly, we use a fuzzy logic based model in this paper. This allows for simulation of dependencies within strategic assembly configuration. The results are transparent and reproducible and support strategic decisions-making. Thus, this method clarifies the correlations between business strategy, product, assembly and production system in developing economies. To evaluate the impact of local conditions on location configuration, we test scenarios such as changing competitive priorities, locations in different countries and product adaptation. The scenarios are tested within the aCar mobility project, a project in which an electric vehicle was designed for local value creation in Africa. The results allow for identifying similarities and differences in strategic recommendations, and therefore to develop a suitable production configuration.
Authors: Matthias Brönner (Technische Universität München), Dominik Fries (EVUM Motors GmbH), Markus Lienkamp (Technische Universität München), Julia Pelka (Technische Universität München),
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Bamboos are evergreen perennial flowering plants in the subfamily Bambusoideae of the grass family Po-aceae. The word "bamboo" comes from the Kannada term bamboo, which introduced to English through Indonesian and Malay. Bamboo is one of the most amply found with remarkable mechanical property. The investigation essences on optimization of treatment parameters to enhancement bending strength of bamboo. Treatment conditions taken at: 500C, 1000C and 1500C with palm oil for 30min, 500C,1000C and 1500C with boil water for 30min. Soaking with water for 30min,1hr and 1.5hr, baking with for 20min, 40min and 60min at 1500C and exposing to smoking for 30min, 60min and 90min. The optimum results obtained on specimens treated in water soaking for 90min; boiled in oil with 1500C for 30min; boiling in water for 30min at 1500C; smoking for 90 min and baking at 1500C for 60min results the best performance on bam-boo sample ultimately. Optimization confirmed with predicted bending strength and achieved 73.11% of enhancement.
Authors: Assefa Asmare Tsegaw (Bahir Dar University),
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This research described the development of a test setup and performance evaluation of a Multistage Evaporative Desert Cooling System (MEDCS) (Cooling - Humidification - Cooling -Dehumidification) by considering the advantage of indirect evaporative system and overcoming the disadvantages of direct evaporative cooling system using copper tubes and Honey comb cooling pads. In this research the maximum performance in multistage evaporative cooling at 2450 rpm. The best parameters are found at this rpm are temperature 23.6℃, relative humidity 63%, specific humidity 0.13 kg of water vapors/kg of dry air, dry bulb temperature 38℃, dew point temperature 10℃, wet bulb temperature 13℃ and enthalpy 75 kJ/kg at average consumption of 8.07L/h. In multistage evaporative cooling, after reached required relative humidity and specific humidity, by switching off direct evaporative cooling system we can maintain same room temperature by running indirect evaporative cooling technology without any addition of moisture. Acknowledgments: This Project is sponsored by the Samara University, Samara, Afar, Ethiopia, under research and community Service. Awarded best research and researcher of the year 2018/2019 for multistage desert cooling system innovation.
Authors: D Somashekar (Samara University), kezal Mohammed (Samara University), Wegaso Urmale (Samara University), Ali Adem (Samara university),
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Friction Stir welding process is suitable for the joining of similar and dissimilar materials. At the current epoch, many transportation industries utilize friction stir welding by lightweight higher strength weld properties. However, many prob-lems are associated and diminution on the weld quality by a shortage of skills. One of the challenges of researchers/fabricators in doing of friction stir welding is not able to choose appropriate process parameters that would produce an out-standing welded joint. In addition to this, they are suffering from selecting opti-mization techniques to predict the welding parameters precisely without consum-ing time, materials, and labor effort. However, it is difficult to select appropriate process parameters and optimization techniques for single and multiple response studies. The current scenario focused on the determination and identification of appropriate process parameters and optimization techniques for welding of 6061AA materials in friction stir welding. All process parameters and optimiza-tion techniques are intensely studied from the previous kinds of literature and identified appropriate process parameters for 6061AA materials. Based on the results, a rotational speed of 47.31%, traverses speed of 17.92%, tool tilt angle 7.64%, axial force 7.09%, shoulder diameter to pin diameter D/d ratio 3.96%, and other parameters are 1.73% contribute for getting a higher hardness and ten-sile strength of 6061AA.
Authors: Eyob Sefene (Bahir Dar institute of Technology),
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