Institute of Technology

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The Institute of Technology focuses on education, research, and innovation in engineering, technology, and applied sciences to support sustainable development.

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    VOLTAGE CONTROL OF A DC-DC BUCK CONVERTER FOR ELECTROLYSIS USING FRACTIONAL ORDER SLIDING MODE CONTROL
    (Hawassa University, 2020-10-22) DEMOZ LISANEWORK WELDETSADIK
    Switching DC-DC converters are non-linear and the most widely used circuits in power electronics. Generally, they are used in all conditions where there is need of stabilizing a given DC voltage to a desired value. DC-DC buck converters are used in voltage step down applications. A DC solar energy is converted to the desired voltage level using the a buck converter, for hydrogen generation with electrolysis process have been investigated. The electrolysis load for hydrogen production especially needs low voltage and high currents. To have these conditions the converter must be designed and controlled sensitively. For this aim, the fractional order sliding mode (FOSM) controller is used as a solution in this paper. Simulation results showed that, FOSM controller improved the rise time and settling time by 2% and 15.3% respectively compared the values using PID controller. Similarly, FOSM controller shows comparatively best performance improvement over SOSM in terms of high reduction of unwanted oscillation in addition to the rise time, settling time improvements. The overshoot is reduced from 46.3% to 5.208% using PID controller while it is totally removed when SOSM and FOSM controllers are applied. Both SOSM and FOSM controllers overcome the effect of electrolysis load variations. The actual output voltage is not deviated from desired value even for large input voltage variation using FOSM controller. Furthermore, the performance of controller was tested by increasing and decreasing 58.52% electrolysis load from operating point while desired output voltage is decreased by 50% and increased up to 20% from operating point. Generally, from the above analysis results it is evident enough that FOSM is better and preferable controller than the SOSM and PID controller
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    IMPROVING COMPETITIVENESS OF SMALL AND MEDIUM MANUFACTURING ENTERPRISES THROUGH SUPPLY CHAIN MANAGEMENT: A CASE OF LEATHER PRODUCTS MANUFACTURING ENTERPRISE IN HAWASSA CITY
    (Hawassa University, 2021-10-22) TAMIRAT YOHANNES GONDALO
    Small and medium leather products manufacturing enterprises are one of the enterprises provides expectation for the government to achieve target as one of the competitive sector in current market for economic growth, employment generation and building an industrial economy. In the different the enterprises has recorded very stagnant level of competitiveness with dynamic current market cause of gap on practicing supply chain managements. In order to conduct this research, questionnaire was developed and distributed for 132 respondents in eleven leather products manufacturing enterprises those work on different department and level. All the questionnaires were collected by using schedule data collection method; beside the questioner interview and detail observation also conducted with experts to supports the findings from the questionnaire. Then the collected data was analyzed using IBM SPSS 26; in both descriptive and inferential statics. Regarding the descriptive statistic and inferential statistics results the finding shows; the current supply chain management practice level of the leather products manufacturing enterprise is medium, this indicate its influence on their competitiveness. Regarding the correlation, all the independent variables are positively and significantly correlated with dependent variable with a significant level of less than 1%. As per the regression analysis output result the coefficients of four predictor variables are statistically significant at less than one percent (P<.001). Therefore, the purpose of this study is to propose ways to improve the competitiveness of small and medium leather products manufacturing enterprises through Supply Chain management and applying competitive priority on operation. Finally the study proposed adoptable SCM framework and recommended the manufacturing enterprises are using supply chain management practices and applying competitive priority to customer value and need with the proper support and guidance of governments in order to improve their competitiveness
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    APPLICATION OF HYBRID APPROACH FOR WOLAITA LANGUAGE PART OF SPEECH TAGGING
    (Hawassa University, 2020-03-24) BIRHANESH FIKRE SHIRKO
    The aim of this research is to develop part-of-speech tagger for Wolaita Language using hybrid approach. Part of speech tagger is one of the subtasks in natural language processing (NLP) applications which is vital for other NLP tasks, like parser, machine translator, speech recognizer and search engines. It is a process of labeling a corresponding part of speech (PoS) tag for a word that defines how the word is used in a sentence. The PoS tagging for Wolaita language is not sufficient yet to be used as one important component in other natural language processing (NLP) applications. In this thesis, the development of part of speech tagger using hybrid approach that combines HMM and transformation based learning approaches is conducted for Wolaita language. In general, HMM model needs large data to increase the performance and the transformation based learning model learn rule based on the language features. The HMM model tags the words based on the optimal path for a given sequence of words and transformation based learning is a rule based model that tag the words based on rules; it learns rule directly from the training corpus without expert knowledge. The developed hybrid approach of Wolaita language PoS tagger uses HMM tagger as initial annotators and the rule based tagger as a corrector based on fixed threshold values. For implementation and experiment, the author used python programming and NLTK. For training and testing the model, 14,358 untagged Wolaita language words are collected from three different categories (Bible, Social media in Wolaita language (Wogetta FM 96.6) and Wolaita language department). The annotation of corpus performed manually by two language experts. For tagging purpose 26 PoS tag are identified based on the work of Berhanu H., work of wakasa (2008) and with help of language experts. From the entire corpus, 90% is used for training and the remaining 10% is used for testing purpose. The performance of the three taggers is tested by using different experiments. After experiment the researcher found that the performance of HMM, rule based and hybrid taggers shows 88.14%, 92.96% and 94.82% respectively. Generally, hybrid approach showed the better performance to assigning part of speech tag for Wolaita language sentences
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    EVALUATING THE PERFORMANCE OF HEC-HMS AND SWAT HYDROLOGICAL MODELS IN SIMULATING THE RAINFALL RUNOFF PROCESS FOR DATA SCARCE REGION OF ETHIOPIAN RIFT VALLEY LAKE BASIN
    (Hawassa University, 2020-10-23) MOHAMMEDRESHID ABDALA ALIYE
    Several physically-based and distributed watershed models have been developed to model the hydrology of the watershed. For a specific watershed, selecting the most suitable hydrological model is necessary to obtain good simulated results. In this study, two hydrologic models, Soil and Water Assessment Tool (SWAT) and Hydrological Engineering Centre–Hydrologic Modeling System (HEC-HMS), were applied to simulate streamflow in the Katar river basin, Ethiopia. The performances of these two models were compared to select the right model for the study basin. Both models were calibrated and validated with streamflow data of 11 years (1990- 2000) and 7years (2001-2007) respectively. Nash-Sutcliffe Error (NSE) and Coefficient of Determination (R2 ) were used to evaluate the efficiency of the models. The results of calibration and validation indicated that, for river basin Katar, both models could simulate fairly well the streamflow. SWAT gave the model performance with the R2 > 0.78 and NSE > 0.67; and the HEC-HMS model provided the model performance with the R2 > 0.87 and NSE > 0.73. Hence, the simulated streamflow given by the HEC-HMS model is more satisfactory than that provided by the SWAT model
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    PERFORMANCE OF HOLLOW CONCRETE BLOCKS WITH CRUSHED WASTE GLASS AS PARTIAL REPLACEMENT OF FINE AGGREGATE
    (Hawassa University, 2020-10-23) YOSEF KUMA AYANA
    Construction is booming in developing countries like Ethiopia. As construction is increasing, demand and price of the construction materials are increasing. Among building construction components hollow concrete block is being widely used. From concrete block making materials fine aggregate is higher constituent. The uses of river sand as fine aggregate leads to exploitation of natural resources and also environmental concerns related to the disposal of various waste materials have escalated to a worrying level, among those: crushed wastes glass is one of them. Therefore, to make the construction industry sustainable, the use of waste materials in place of natural resources is one of the recommended. The main objectives of this study was to investigate the performance of class C hollow concrete blocks with crushed waste glass as partial replacement of fine aggregate and to determine the replacement percentages at which crushed waste glass can be effectively put into service and also compare the cost of crushed waste glass partially replaced in hollow concrete block with the conventional ones. The method used was experimental study. The crushed waste glass partial replaced fine aggregate with 10%, 20% and 30% by volume and the control mix was prepared. The compressive strength test was carried out at the 7th, 14th and 28th days, whereas the density and water absorption tests were carried out on the 28th day. As per the finding, the control mix compared with the replacement specimen, the density is decreased as the proportion of crushed waste glass increases and decreases by 5.6% at a 30% replacement, the water absorption decreases as crushed waste glass content increases and it decreased by 2.5% at a 30% replacement, the compressive strength with up to 20% replacement increases by 59.72%, but after that, it starts decreasing for 30% replacement by 10.64%, results showed that replacement of 20% fine aggregate by crushed waste glass was found to have optimal compressive strength, and also the production of block using 20% crushed waste glass saves cost compared to the conventional once by 2.06% in 1m2 area.
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    EFFECT OF SOIL BUND ON SELECTED SOIL PROPERTIES AND ASSESSING FARMERS´ ADOPTION OF PHYSICAL SOIL AND WATER CONSERVATION TECHNOLOGIES; A CASE STUDY OF FANTA WATERSHED GENA BOSSA WOREDA, SOUTHERN ETHIOPIA
    (Hawassa University, 2019-10-22) Wondimu Bekele Goba
    Land degradation is one of the major challenges in agricultural production in Ethiopia. To combat the problem various Soil and Water Conservation (SWC) measures were introduced in the country. Soil nutrients assessment is valuable for evaluating agro-ecosystem sustainability, soil degradation and identifying land management practices. This research aimed i) to evaluate the effect of soil bunds on selected soil properties (soil texture, soil organic carbon, phosphorus, potassium and nitrogen); ii) to assess the adoption of farmers and factors influencing physical soil and water conservation (SWC) technologies in the Fanta watershed. Twenty-seven soil samples at 3 slope positions were collected from soil bund and 9 soil samples at 3 slope positions were collected from no bund plots. Samples were taken at 0-20 cm, depth. Analyses were done for soil texture, soil organic carbon (SOC), available phosphorous (AP), available potassium (AK) and total nitrogen (TN). In addition, 128 households were selected from three kebeles for interview to evaluate soil and water conservation (SWC) measures adoption. The results showed that SOC, AP, and AK were significantly (p≤0.05) increased and decreased by the soil bunds and slope positions. Sand and clay fractions significantly varied with both soil bunds and slope gradient but silt and TN, was not significantly differed in no-bund plots within its slope and adjacent conserved plots. The highest values of most parameters were recorded in lower slope positions both in bund and no-bund plots and near soil bund at upslope side. Farmers differ in their willingness and ability to adopt new practices. Adoption of physical SWC was negatively correlated to age of head of household, family size, farm size, plot numbers and livestock numbers while education level, location of land, extension service and access to training were positively and significant difference. Thus, it can be concluded that soil bunds retain essential plant nutrients but its adoption was limited due to some socio-economic factors in the Fanta watershed. Therefore, Structures were not regularly maintained thus, there should be a continuous awareness creation mechanism on stakeholders and prevent cropland from open grazing. In addition, emphasis should be required on variables which negatively affecting adoption of physical soil and water conservation technologies
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    DESIGN AND SIMULATION OF DC MICROGRID FOR ELECTRIC VEHICLE CHARGING STATION (A CASE STUDY HAWASSA CITY)
    (Hawassa University, 2020-08-17) MATHEWOS HADERO GUTENA
    Development of electric vehicle has been established as an effective way to ensure energy security and realize emission reduction. However, the public electric vehicles charging station which is important element of using electric vehicles is not installed in Ethiopia. Therefore design of DC microgrid for charging station is proposed in this paper. In Ethiopia the electric energy infrastructure is not modernized enough and it is really difficult to fully depend on the energy obtained from grids. Thus, it is important to integrate the renewable energy (solar), grids and energy storage. However, the reliability of integration of renewable energy is dependent on the ability of the system to accommodate expected and unexpected changes (in production and consumption) and disturbances, while maintaining quality and continuity of service to the customers. Thus to improve real-time control performance and reduce possible seasonal variation forecasting is proposed for the solar energy used in the system. Thus in this study the author used the metrological data from Hawassa station and used machine learning algorithm for train the model with collected data and python used as programming language to develop forecasting model score system. Python is one of a well known high level programming language in data science.In this thesis, Jupiter notebook is used to write Python codes to develop a solar energy forecasting system.The designed forecasting system can predict the next day irradiance with accuracy of 97.56%. Next MATLAB simulation tool is used to integrate system. The proposed maximum operating voltage of this DC microgrid charging station is 500 Vdc. Power flow management using fuzzy logic controller keeps voltage within expected range with standard voltage deviation 2.2 and improved the response time 1.645 ms. More over the author also investigated the operating costs per year for this design. The operating costs for energy is $43,651per year if you use grid only for charging of EVs. On the other hand if 400 kW of PV and 680 kWh of battery capacity is integrated to the grid it reduce the operating costs to$6,344 /yearwith annualized saving of $37,306.This implies as the hybrid system has investment payback of 3.06 years and an IRR of 32.7%.Thus, clearly the result obtain in this thesis have great potential in future charging station design
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    IMPACT OF CLIMATE CHANGE ON AGRICULTURAL WATER DEMAND: THE CASE OF BILATE RIVER CATCHMENT
    (Hawassa University, 2019-10-27) ZEKIWOS KEBEDE KARISA
    Climate change has impact on agricultural water demand by affecting the different climate variables such as temperature and rainfall. This study was carried out to detect the impact of the climate change on agricultural water demand under different time horizon to prevent vulnerability to climate change at Lower Bilate River sub-basin. The data used in this study were collected from National Meteorology Agency of Ethiopia, Ministry of Water, Irrigation and Electricity. Simulated climate data were obtained with using single climate model ICHEC-EC EARTH, Precipitation and temperature time series of historical and projected time period. The scenarios used were from the Eth_CORDEX_Grids archive based on RCP4.5 and RCP8.5 Scenarios. The trend analysis for the last 32 years, indicated that the impact of the climate change to changes in long-term maximum and minimum temperature is increased by 0.0395o c and 0.1380 c respectively and changes in precipitation is by the factor of the -0.83, the prediction analysis indicates that precipitation at the study area will be -35.71% and -40.18% for the year 2048 and 2080 respectively from RCP4.5 Scenarios. Whereas, based on RCP8.5 Scenarios the change in the same order will be -48.90% and -60.11%. As a result the change is expected in agricultural water demand for the selected crops at specific study area. The average irrigated agriculture water demand of selected crops Tobacco and cotton are found to be 19.01Mm3. However, this value is not kept constant as a result of the change in climate that for future time period (2017-2048) and (2049-2080) found to be 24.01Mm3 and 25.01Mm3 respectively for RCP4.5, and in case of RCP8.5 is found to be 25.33Mm3 and 28.36Mm3 respectively. Whereas, the Rain fed agriculture water demand for the crops maize and haricot bean are estimated 87.98Mm3 at the study area. As a result, the change in climate computed as 86.65Mm3 and 104.28Mm3 for the period of 2048 and 2080 respectively for RCP4.5 Scenarios, whereas based on RCP8.5 Scenarios the change will be 100.39Mm3 and 125.42Mm3 respectively
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    EVALUTION OF THE CONTRIBUTION OF GEOMETRIC DESIGN OF THE ROAD INTERSECTION IN ALLEVIATING TRAFFIC ACCIDENT IN SHASHEMENE TOWN
    (Hawassa University, 2020-08-18) YASIN ASSEFA MOSSA
    Efficiency of intersections contributes significantly towards the efficiency of urban road networks. Whereas intersections constitute a very small part of the entire transportation network, more than 50% of all motor vehicle accidents occur at intersections. Because of the overrepresentation of intersection-accidents, intersections require special attention in the planning and designing of road networks. Thus, the main aim of this research study is the evaluation of the contribution of geometric design of the road intersections in alleviating traffic accident in the Shashemene town. Abosto and Kudus Mikael signalized intersections while Tekliye, Semaniyaand (81), arada Sefer, Gibrna, Zero Amst (05) and Mobile non signalized intersections were chosen for this thesis. These intersections were selected for the study from different locations within the town. They have more traffic accident than any other similar junctions do in Shashemene town. The geometric, traffic and accident data were collected during the morning and afternoon peak time periods using site observation, field measurement and video camera in each of the selected junctions. The study use four distinct scientific principles namely: accident frequency, accident rate, empirical Bayesian and critical accident method to identify black spot locations at selected intersections. Out of the methods, empirical Bayesian proved superiority so that much of the conclusion was based on this method. Log linear Poisson regression and Negative binomial regression model was used to investigate the effect of road geometric design elements on the road crash occurrence in the selected junctions.The results of paper proved that road junction Semaniyand, Tekliye, Kudus Mikael and Abosto were highly prone to accidents than other road junctions in Shashemene town with adjusted accident frequency values of 27.85, 26.54, 25.25 and 22.65 respectively. And also the result of this study shows, there is a strong correlation between road geometric design elements and road crash occurrence. The modeling result indicated that the explanatory variables such as lane width, super elevation, gradient, and intersection sight distance, shoulder width, median type, and median width, angle of intersection, side walk width and curves radius had significant effects on the occurrence of road traffic crashes
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    CORRELATION BETWEEN INDEX PROPERTIES WITH SHEAR STRENGTH PARAMETERS FOR HAWASSA SOIL
    (Hawassa University, 2017-04-23) BATAMO BELIHU
    Shear strength parameters (angle of internal friction and cohesion) are the key engineering properties of soil. In every situation finding these parameters by laboratory testing or by using advanced equipment may be uneconomical for clients during the preliminary design phase. So it is a common practice in geotechnical engineering to estimate these parameters by employing empirical equations from easily found engineering properties of soil. Correlations and empirical equations developed are site specific, and a good result will be found using them for soils from which they are developed. In this study an attempt was made to correlate shear strength parameters (angle of internal friction and cohesion) for Hawassa city soil from index properties. Detailed analysis was carried out by randomly taking thirty four samples from seven sub cities of Hawassa city. The sampling pits were dug manually using hand tools with plan area of 1.50 m by 1.50 m at depth of 3.0 m from the ground surface. From laboratory test results, most samples were found to be with very low values of density and no plasticity. The soil was classified as cohesionless soil of fine to medium sized sand with group name silty sand, sandy silt, silty, clayey sand, silty, clayey sand with gravel and well graded sand with gravel consecutively. Due to the nature of the soil, cohesion was exempted from correlation. The Influence of easily found index properties of soil on its shear strength parameter was studied, and a regression carried out for the selection of most influencing variables. This parameters identified as the grain size distribution, density, and water content of the soil