Ethiopia Institute of Technology- Mekelle

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Developing Trip Production and Mode Choice Model for Home Based Trips: The Case of Hawelti Sub-City Residents, Mekelle - Ethiopia
(Mekelle University, 2020-03-25) Gerezgiher Gebrewahd Hagos
Hawelti sub City considered one of the most rapid increases in population and crowded subcity in Mekelle city. Hawelti sub-city does not have a transportation model; hence, developing a model is considered very important for predicting the average daily trips and use of each mode. The aim of this study is to develop trip production and mode choice model for home-based trips in Hawelti sub-city residents. The trip production includes a trip for work, education, shopping, social and recreation whereas the mode choice focuses on work and education trips. A household interview survey was used as a data source in addition to secondary data obtained from the municipality of Hawelti Sub-City. Trip production was analyzed using multiple linear regressions and multinomial logistic regression was utilized in the analyses of mode choice with statistical data processing software SPSS. The modes of transport considered in the model are Walking, Bajaj, Private car, Minibus Taxi, and Service (Company or school provided transport). Minibus taxi is found to dominate with 44% share followed by the company provided service with a 22.8% share for all trips. In the developed model the factors that affect the trip production are the number of students, employed persons, monthly income, the number of females and the age above 45 in the household. Moreover, the factors that significantly affect the choice of transport modes for employees were total travel time, work type and family size. The mode choice model developed for the case of students the significant factors were found to be travel time and gender. The developed models were significant at 95% confidence level and exhibits a good fit for the data with the coefficient of determination (R2 ) of 0.889 for the general trip production and the adjusted goodness of fit measure statistics rho square (ρ2) of 0.823 and 0.824 for the work and student models respectively for the whole study area. The models are validated to be capable of predicting 90.97% and 87.2% of the preference of trip makers for the work and education mode choice models respectively.
Effect of Filler Types (Crushed Stone, Gypsum and Lime Kiln-dust) on the Marshal Properties of Asphalt Concrete
(Mekelle University, 2020-05-18) FREWEINI WELU
Roads are one of the country’s basic infrastructural facilities, which needs a precise engineering design to minimize the life cycle cost by achieving reliable in-service performance. For the paved road types, pavement structure design and mix design of asphalt concrete mixture including adequate structure with proper drainage system and durable raw materials are the major considerations to attain reliable pavement performance that is adequately strong, durable and resistive to fatigue, and permanent deformation by considering economical aspect. The HMA contains coarse aggregate, fine aggregate and mineral filler coated with a bitumen binder and air and the mechanical properties of bituminous road pavement depend decisively upon the properties of its filler-bitumen. Although Mineral filler plays a major role in filling voids of the mixture and on the modification of the asphalt concrete properties like stiffness of the asphalt mortar matrix, improving the rutting resistance of pavements, it needs high intention on the content of the mineral filler since the excessive use have also weaken the properties of the mixture. In Ethiopia, crushed stone from dust extractor is conventional filler material in almost all flexible pavement construction projects but deficiency of this mineral filler happens and leads to crush aggregate for that purpose, which increase the production cost and environmental deterioration of the area. The main objective of this thesis is therefore to investigate the effect of the filler types (crushed stone, lime kiln-dust, and gypsum) on the marshal properties of asphalt concrete and to analyze the cost breakdown for the production of hot mix asphalt with these different filler types. To evaluate the effect of these selected filler types marshal mix design was used and conducted the laboratory test for marshal stability, flow, air void, voids in mineral aggregate and voids filled with bitumen by preparing a total of 90 specimens compacted by marshal compactor by 75 blows on the upper and lower sides of the mold. From the marshal laboratory test, asphalt concrete with crushed stone, gypsum and limekiln dust attains all the requirements specified on the ERA manual. Comparing the filler types, mixture with crushed stone filler attains the highest stability (9.45KN) at 2% filler content. For the asphalt concrete mixture at 3% filler content, mixture with gypsum filler attains the highest stability (9.4KN). From the cost break down analysis for the production of 1m3 HMA, lime kiln-dust and gypsum lowers the production cost by 1.34% and 1.21% respectively with the comparison of HMA with crushed stone filler.
EVALUATION OF SUSTAINABLE URBAN MOBILITY IN THE CITY OF MEK’ELE
(Mekelle University, 2020-06-28) Yoseph Solomon
Currently, cities are looking for all round transport sustainability. Nevertheless, urban transportation can create a problem on economic, social and environmental aspect of the city. Up on observation residents have complaint on the fare for local transportation, vehicles noise disturbance and services provided by public transport. This thesis indexed eleven urban sustainable transport indicators. Based on the indexed results of the tool, SWOT analysis is conducted. The study also sought to identify the remedial measures that should be undertaken to mitigate the problems. The study area is defined to be Mek’ele city. The sustainable urban mobility indicators are assessed through a procedure that requires various method of data collection and data processing. World Bank backed online software was used after data legitimizing and confirmation was made between Tigray Construction Road and Transport Bureau and the world councils of urban sustainable development headquarter at Geneva, Switzerland. The indicator, access to mobility service, is based on percentage of people living within a radius of 400 meters from a public transport stops. Fatalities were considered as the number of deaths per annum per 100,000 inhabitants. For mobility space usage, area of roads, open parking, service areas and petrol stations were considered. Length of road network with sidewalks, with bike lanes, in zone 30 (km/h) and total length of city road network were served as input for the indicator of opportunity for active mobility .The social aspects such as, access for mobility impaired groups, comfort and pleasure, commuting travel time and security is indexed using structured questionnaire as part of the tool. For noise hindrance, sound measurements were taken. Affordability of public transport for the poorest quartile is measured by GDP and population’s lowest quartile income as a data. The sustainability for Mek’le city transport system is 4.93/10, suggesting weak sustainable mobility conditions for the city‘s transport system. The SWOT analysis has the prospects of being used in policymaking, defining strategic directions and the implementation of measures towards the fulfilment of sustainable urban mobility in the city of Mek’ele.
Estimating Traffic Congestion Costs for selected Road of Mekelle City
(Mekelle University, 2020-06-28) Wahd Solomun
Traffic congestion is a problem which occurs on road network characterized by slower speed, longer trip time due to excessive vehicles from different direction. Traffic congestion have a negative impact on society such as late reach to work place by increasing travel time, on health by creating stress, mentality and physical discomfort, increasing fuel consumption and air pollution. Mekelle is one of the fastest growing city in Ethiopia. Accordingly, traffic congestion is growing extremely in the city and results time wastage on travel and other direct and indirect effects on the society. This study is concentrated on two selected intersection the first one is four leg signalized intersection which is found around commercial bank of Ethiopia, main branch and the second one is four leg intersection which is found around Relief Society of Tigray in this intersection traffic light is not functional for about two years but after data collection performed the traffic signal was maintained and the intersection become signalized. Then again traffic volume data was conducted at signalized case. The main objective of this study is to estimate traffic congestion costs for selected intersection of Mekelle city and to suggest the possible counter measure for the problem. Primary and secondary data was collected to accomplish the study objectives. Primary data traffic volume, vehicle occupancy, signal timing, geometric data and daily labor cost was collected. The traffic volume count was made using video recording starting in the morning peak time 7:00AM-10:00AM, at noon time 11:00 AM-2:30 PM and the evening peak time 4:30 PM- 7:30 PM at 15 minutes interval was done for both intersections. The vehicles were counted by type passenger car, bus and small and medium truck vehicles. The average vehicle occupancy was collected based on traffic engineering vehicle occupancy data collection manual. After the data was collected data analysis was made. Delay at the intersection was analyzed using SYNCHRO software. Then using the collected data and delay annual peak hour cost of traffic congestion in both intersection was estimated. The cost of congestion consists travel time cost, fuel consumption cost and cost of co2 emission gas due to excess fuel usage. The result is found about (5,339,609.37ETB annual peak hour cost) at CBE four leg signalized intersection, (3,789,746.99ETB annual peak hour cost) at REST four leg unsignalized intersection, and (3,181,684.41ETB annual peak hour cost) at REST four leg signalized intersection. Annual peak hour travel time cost represents the opportunity costs of wasted time on congested intersection which shows the largest category at CBE intersection found about 4,311,552.5ETB nearly 81% of total cost of the intersection, at REST unsignalized is about 3,116,165ETB about 82% of cost of intersection and REST signalized have 2,618,690.9ETB about 82% of total intersection cost. Meanwhile annual peak hour cost of fuel is the second contributor to the overall cost of congestion with 1,009,870.3ETB at CBE, 661,988.9 ETB at REST unsignalized intersection and 552,987.4 ETB at REST signalized intersection which is about 18% of the total cost. On the other hand annual peak hour emissions costs is the least contributor to the overall cost of congestion and estimated about 18,186.57ETB at CBE intersection, about 11,611.09ETB at REST unsignalized intersection and 10,006.11 ETB at REST signalized intersection. The cost of congestion result shows the effect of congestion is highly concentrated on the travel time of public transport users’ means 78% of the travel time cost is for the public transport users.
Pavement management system development for Mekelle city road network and prioritization of roads for maintenance based on their performance index
(Mekelle University, 2020-06-28) Hadush Hagos
Pavement represents an important asset which is a pillar for the economy of one nation and this demands well-organized asset management. In Mekelle city, intensive investment has been made on constructing and maintaining roads at a network level. The current maintenance strategy followed by Mekelle city municipality is reactive. It responds to a problem after it has occurred. Instead of providing preventative maintenance at an early stage, roads are left until much more expensive reconstruction is needed and this maintenance delay will induce rising cost. This, in turn, causes spending a large amount of money to maintain extensively distressed pavements. The network needs great caution through periodic evaluation of pavement conduction and timely maintenance to keep the network operating under an acceptable level of service. This research work is intended to develop web-based flexible pavement management system software for Mekelle city road networks which will support the local road agency on road maintenance decisions. The developed decision supporting tool software compiles the basic components of a pavement management system using MySQL as a database creating quarry language and PHP software creating platform. The components of the pavement management system are framed as input data, analysis part and reporting tool for the outputs of the analysis section. The software uses road inventory data, road condition assessment data, road section data, and road traffic survey data as input. Storing all this data on its database the software utilizes those data to make pavement performance evaluation analysis employing the pavement condition index as a performance indicator. A case study of 6 km main access road segmented to eight sections was inspected to analyze the proposed pavement management system software. Finally, the software reports the results of the analysis part in the form of road Id, pavement condition index, rating scale, repair alternatives, and maintenance strategy as end results of the analysis for each road on the network then a priority for maintenance is made based on PCI value. In addition to this, the developed system can perform life cycle cost analysis for each road on the network employing net present value as economic evaluation criteria. According to the analysis result of the developed software, Alula Street i.e. form commercial bank of Ethiopia to Romanat roundabout is with least pavement condition index value, a PCI value of 11.17, a rating scale of very poor, and the corresponding maintenance strategy is reconstruction.
ANALYSIS & DESIGN OF STEEL WIND TURBINE TOWER UNDER COMBINED EFFECT OF WIND LOAD AND EARTHQUAKE
(Mekelle University, 2020-08-09) Negassi G/kidan
SELECTION OF SUITABLE TRAFFIC MODEL USING FUNDAMENTAL DIAGRAM UNDER DIFFERENT ROAD GEOMETRY AND OPERATING CONDITION IN MEKELLE CITY SUB-ARTERIAL ROADS
(Mekelle University, 2020-08-28) Bereket G/Egzabher Berhe
The relationship between macroscopic traffic flow parameters (flow rate, speed, and density) is represented graphically by fundamental diagrams. These diagrams play an important role in traffic flow theory and transportation engineering. Most conventional traffic stream models are mainly applicable for homogenous traffic conditions. These models are not suitable for the traffic condition of Mekelle city which is characterized by weak lane discipline and heterogonous in nature. This thesis select suitable traffic model for different roadway geometry and operating condition. It also compares the flow parameters for the stated traffic condition. For this thesis three different cases have been considered, those are road way with and without median structure, road way with and without footpath and road way with and without side market. Traffic data collection is done through video recording at midblock rod from six different locations. To select the suitable traffic model the speed –density plot of field data for different locations is fitted with five established FD models linear, polynomial 2nd degree, polynomial 3rd degree, exponential and logarithmic. From the result, polynomial 3rd degree is the best FD model for case one which compares the roadway with and without a structural median. For the second case which comprises roadway with and without footpath, exponential models are the best-fitted model, but hence it doesn't satisfy the boundary condition to compare the flow parameters polynomial 2nd degree is the second best model. Similarly, for case three which compares roadway with and without side market the exponential and 3rd-degree polynomial is the best-fitted models, but hence exponential model doesn't satisfy the boundary condition to compare the flow parameters 2nd-degree polynomial is the second-best fitted model. It is also found that free-flow speed trends decrease if there is no structural median, footpath and if there is a road side activity by (4.8%, 6.19% and,9.11%). The jam density increases if there is no structural median, footpath and if there is a road side activity by (41%, 8.8% and, 6.68%) consecutively.
Three-Dimensional Finite Element Analysis of Dowel-Concrete Contact Stresses In JPCP Using Abaqus 6.14.
(Mekelle University, 2020-09-21) Goytom Gidey Desta
Jointed Plain Concrete Pavements (JPCPs) are the most common and applicable type of rigid pavement in road and airfields. Yet, it has been very common to see JPCP failed at transverse joint, globally. Study of dowel-concrete contact interface behavior and induced concrete contact stresses at this interface has received significant attention in recent years because of its relevance to overcome transverse joint problem and design effective doweled joints in JPCP. However, most of the previous studies relied on simplifying assumptions that neglected the exact dowel concrete interface behavior. With the above context, this thesis addresses a numerical analysis of contact stresses and strains at dowel-concrete interface and load transfer efficiency (LTE) in JPCP by means of FEM. So as to attain this objective, a nonlinear 3D-FEA was performed using a commercial software package, ABAQUS (6.14). Moreover, theoretical calculations were done based on friberg‟s closed form solution for verification of the FEA result, and a slight difference was achieved. The analysis was made to understand the effect of transverse joint parameters on dowel-concrete contact stresses and LTE. According to the outcome of this thesis, the decreasing of friction value that represents dowel-concrete bonding form 1 to 0.05 resulted decrease in bearing stress and LTE by 0.66% and 0.69%. Also, as the concrete weight increased by 28.57% (from thickness of 250mm to 350mm), the bearing stress decreased by 3.05% and LTE increased by 0.69%, for the 15.78% increase in dowel bar weight, the bearing stress decreased by 12.5% and LTE increased by 2.56%, for the change in joint width form 10mm to 12mm the bearing stress increases with 3.45% and the LTE decrease about 0.86%, for 46.67% increase in axle load, the bearing stress increased by 60.90% and LTE decreased by 5.23%, for 96.5% increase in stiffness of the base course (from 350MPa. to 10,000MPa.) the bearing stress decreased by 60.90% and LTE increased by 7.93%. In addition, for a change in modulus of dowel support from 4.07MPa/m to 6MPa/m, the bearing stress increased by 0.79% and LTE by 1.22%. Form effect of dowel bar misplacement, for the 30mm vertical misplacement a single bar misplacement produced 2.66% higher bearing stress and 0.76% less in LTE than two bars. In general, it can be concluded that a 3D-FEM is a promising approach for modelling JPCPs.
Fuel blending Options in cement pyro processing of Messebo Cement factory by Co firing of Sawdust and Coal
(Mekelle University, 2024-01-25) Guesh Tewele G/her
This research assesses the technical, economic, and environmental viability of co-firing biomass fuels (eucalyptus sawdust, olea sawdust, and pine sawdust) alongside coal in cement manufacturing at Messebo Cement Factory. The evaluation emphasizes fuel blend composition, calorific values, combustion properties, and the potential for emissions reduction. Employing a mass-based fuel blend composition model, the study determines the molar composition of the blended fuels while examining their performance across 10%, 15%, and 20% co-firing ratios. Key results indicate that co-firing biomass significantly lowers CO₂ emissions compared to coal. At a co-firing rate of 10%, eucalyptus sawdust emits 0. 46426 kg of CO₂ per kg of cement, in contrast to 0. 760 kg for coal by itself. This results in a CO₂ emissions reduction of 0. 304875%, which escalates to 1. 009417% at a co-firing rate of 20% for olea and pine sawdust. The flame temperature of 1770 K (1497°C) for 10% eucalyptus co-firing satisfies kiln operational specifications, confirming its technical feasibility. From an economic standpoint, substituting 10% of coal with eucalyptus yields approximately 75,297,000 birr in annual savings, with savings rising to 150,600,000 birr at a 20% co-firing rate. The cost of eucalyptus (0. 38205 birr/kg of cement) is considerably lower than that of coal (1. 637 birr/kg of cement), leading to a 7. 67% decrease in fuel expenses at a 10% co-firing rate. Moreover, 10% eucalyptus co-firing decreases coal consumption by 5. 6%, which further boosts economic and environmental advantages. Environmental benefits encompass significant reductions in SO₂ and NOₓ emissions. For instance, 20% eucalyptus co-firing decreases SO₂ emissions by 19. 15264 units and NOₓ emissions by 12. 49865 units. Pine sawdust exhibits the greatest reduction in SO₂ (19. 77646 units at 20% co-firing), while olea sawdust achieves the most substantial reduction in NOₓ (13. 02422 units at 20% cofiring). A lower ash content (18. 67% at 20% co-firing) and minimal sulfur content in biomass further enhance combustion efficiency and lessen environmental impacts. The study also underscores the practical use of pine sawdust as an alternative fuel, which lowers the air-to-fuel ratio, excess air ratio, oxygen demands, flame temperature, as well as SO₂ and NOₓ emissions. Locally sourced pine sawdust offers benefits such as decreased transportation expenses, reduced moisture content, and less biological degradation. It can be processed and burned in a manner similar to coal or pet coke, needing only slight modifications. The thesis concludes that co-firing biomass fuels, especially pine sawdust, represents a feasible and sustainable approach to cement production, delivering considerable environmental and economic advantages. It suggests additional actions like waste heat recovery, alternative raw material usage, carbon capture, and the integration of renewable energy to further enhance system efficiency. Co-firing coal with biomass provides significant benefits for cement kiln pyro processing but necessitates precise optimization and execution suited to specific operational circumstances
Design of Fuzzy logic controller to series active variable geometry suspension system of automobile vehicle using full car model (With preview road profile information)
(Mekelle University, 2024-04-07) Binyam Tadros
Recent advancements in electro-mechanical active suspensions are presenting new opportunities, showcasing numerous benefits over traditional passive and semi-active systems, while also overcoming the significant drawbacks of other active solutions. This thesis introduces fuzzy logic controller with perfect preview information to improve the performance of Series Active Variable Geometry Suspension (SAVGS), which enhances conventional independent passive or semi-active suspensions by actively regulating the suspension geometry through an electromechanical actuator. The research work explores the benefits of this suspension type and provides an in-depth analysis of its simplest form. Additionally, it offers insights into the design process, including liberalized full-car modeling and selection. A control system designed to manage pitch and roll attitude of the chassis is also discussed. Simulation results demonstrate the viability of the proposed system as the fuzzy logic controller (FLC) is developed using MATLAB-Simulink for the SAVGS improves the suspension system, with various performance metrics (Passenger Ride Comfort, Suspension Safety, and Road Handling) evaluated at different speed for Road disturbance. The performance response at 20 kilometer per hour shows improvement in all the performance metrics, like in Passenger ride comfort is reduced in Vertical acceleration by 41.67% with reduced pitch and roll acceleration, Suspension safety is reduced in suspension deflection by 49.1% in front and 43.1% in rear sides with reduced velocity, and in road handling the tire deflection reduces by 46.3% at front and 36.9% at the rear sides of the car
Design of a Genetic Algorithm (GA) and Particle Swarm Optimization (PSO)-based Linear Quadratic Gaussian (LQG) regulator for a Series Double Inverted Pendulum on a Cart
(Mekelle University, 2024-04-11) Solomon Teklehaimanot
This thesis focuses on the design of a Genetic Algorithm (GA) and Particle Swarm Optimization (PSO)-based Linear Quadratic Gaussian (LQG) regulator for a Series Double Inverted Pendulum on a Cart (SDIPC). The primary issues motivating the design of this regulator are the unstable behavior of the SDIPC, the slow settling times, and the significant steady-state errors observed in previously designed regulators. For this plant model, the LQG is developed using a cascaded combination of a GA and PSO-tuned Linear Quadratic Regulator (LQR) and a full-state observer, based on the separation principle theory of control systems. This approach is optimal for fully stabilizing the SDIPC and can withstand process and measurement noise through a Kalman filter. The entire system is designed in MATLAB®/SIMULINK®. Simulation results demonstrate that the PSO-tuned LQG achieves faster settling times and smaller steady-state errors compared to the GA-tuned LQG. With the PSO-tuned LQG, the steady-state errors for the upper pendulum angle, lower pendulum angle, and cart position are reduced to 1.033 × 10⁻⁴ rad, 4.206 × 10⁻⁵ rad, and 2.920 × 10⁻⁴ m, respectively. Additionally, the settling times for the upper pendulum angle, lower pendulum angle, and cart position are 0.897 s, 0.711 s, and 0.780 s, respectively. Thus, the regulator design objectives are successfully achieved with the PSO-tuned LQG than with GAtuned LQG.
Developing a Predictive Model for CBR Value Using Soil Index Properties: A Case Study of the Mekelle Asphalt Road Project
(Mekelle University, 2024-04-15) Million Abrha Weldegeorgis
California Bearing Ration (CBR) value is an important soil parameter considered as main design input in the design of flexible pavements and runways of airfields. The design of pavement thickness determined depending on the strength and stability of sub-grade materials are evaluated before construction of pavement by using CBR test. And Index properties of soil are properties which are used to characterize soils and facilitate identification and classification of soils for engineering purposes. However, in a large-scale road project soil properties vary from region to region and season to season as it appears naturally. Thus, developing empirical equations specific to a certain region and soil type could be considered nearly as good insight of soil behavior. This study was conducted to developing a predictive model for CBR value using soil index properties of soils in the case study of the Mekelle Asphalt Road Project. The study was carried out using 27 samples collected from SUR Construction PLC Mekelle Asphalt Road Project. And test procedures were carried out based on the (ASTM) and (AASHTO) at Mekelle Asphalt Road Project Laboratory. This study tries to use a single linear regression model and multiple linear regression models to characterize the strength of the subgrade soils from the soil index properties using a statistical method. The laboratory test results and statistical analysis were carried out using Microsoft Excel and SPSS software. To develop the intended correlation and regression analysis CBR value at different blows such as 10, 30 and 65 blows were considered as dependent variable. And index properties of soil such as percent passing 2.0, 0.425, and 0.075 mm (sieve No. 10, 40, and 200) sieve size, LL, PI, OMC and DD at points 10, 30, 65 blows were considered as independent variables. From the regression analysis result, the equation and coefficient of determination developed are:  CBRat 10 Blow = -7.99 - 0.024LL - 0.025PI + 0.187P10 - 0.133P40 + 0.027P200 - 0.025OMC + 2.68DDat 10 blow, R2=0.913, adj R2=0.881  CBRat 30 Blows = -3.1 - 0.058LL + 0.006PI + 0.133P10 - 0.092P40 + 0.008P200 - 0.055OMC + 2.87DDat 30 Blows, R2=0.965, adj R2=0.953  CBRat 65 Blows = -3.301 - 0.113LL + 0.054PI + 0.085P10 - 0.004P40 + 0.050P200 - 0.088OMC + 1.373DDat 65 Blows, R2=0.928, adj R2=0.902
Identifying and evaluating various regulatory countermeasures to traffic congestion in selected intersections of Mekelle city
(Mekelle University, 2024-06-21) Rahwa Berhe Baryagabr
Traffic congestion reduces the effective accessibility of residents, activities and jobs resulting in lost opportunities for both the public and business. Longer journey times, higher fuel consumption and increased emissions of air pollutants are some of the impacts of congestion. Traffic congestion is a major phenomenon in most intersection of Mekelle city, especially in kedamay weyane sub city. Therefore, this thesis attempts to first evaluate the state of traffic congestion, then offers some suggested countermeasures to lessen the congestion, illustrates the results of applying the countermeasures at the chosen intersections, and finally outlines the factors that contribute to the congestion. The congestion is measured by determining the level of service (LOS) . And the LOS was analyzed by VISSIM software using peak hour turning traffic volume, vehicle composition and geometry of the intersections as input data. For determining peak hour turning traffic volume the calculation is made through the manual counting of vehicles and multiplying by passenger car unit factor (PCU factor) to determine passenger car equivalent (PCE). The LOS output among the 9 selected intersections around kedamay weyane sub city the 6 of them are below D. By applying some regulatory countermeasures for the only 6 congested intersections and reanalyze the LOS of all intersections, most LOS of the selected intersections is become to above LOS C. Even though the LOS of intersection 1 and some turning movements in intersection 8 are decrease after apply the counter measures; because some minibus taxi routes are changes to them, most LOS of the selected intersections are become A, B and C. At final this thesis concluded that high number of bajaj using the intersection, the route of minibus taxi concentrated to one direction, stop vehicles near intersections and illegal trading on walk way and traffic lane are the cause of the traffic congestion.
Feasibility Study of Integrated Hybrid Energy System for off-Grid Rural Electrification: Case of Three Village
(Mekelle University, 2024-09-28) Yeshareg Yrgalem
This research presents a feasibility study of an integrated hybrid energy system designed for off grid rural electrification in three villages in Ethiopia's Tigray region. With over 56% of Ethiopia's population lacking access to electricity, the National Electrification Program (NEP) aims to achieve universal electricity access by 2025, promoting a mix of grid and off-grid solutions. This study explores the potential of combining wind, solar, and biogas to create a sustainable energy model that aligns with the NEP's objectives. The objectives of this study are threefold: to assess the renewable energy resources available in the selected villages, to design and size the components of a hybrid energy system, and to evaluate the technical and economic feasibility of the proposed solution. The methodology involves data collection through site assessments, resource evaluations, load estimations, and modeling using the HOMER Pro software. The study evaluates the energy demands of Felege Mayat, May Shih, and Mayderhu villages, revealing daily energy requirements of 1673 kWh, 1215 kWh, and 785 kWh, respectively. The findings indicate that a hybrid system—combining wind, solar, and biogas—can deliver a sustainable, reliable, and cost-effective electricity supply, with levelized costs of electricity (COE) at $0.0139/kWh, $0.0158/kWh, and $0.0167/kWh for each village. This approach not only addresses the immediate energy needs in these rural communities but also promotes environmental sustainability by reducing dependence on traditional biomass. In conclusion, this thesis highlights the potential of integrated hybrid energy systems to bridge the energy gap in rural Ethiopia, promoting sustainable development and improving human wellbeing. Recommendations for future research and implementation strategies are provided to facilitate the adoption of such systems in similar contexts.
STUDY ON TIME AND COST PERFORMANCE ASSESMENT OF PUBLIC CONSTRUCTION PROJECTS IN TIGRAY REGION: A CASE STUDY IN ABIADI TOWN
(Mekelle University, 2024-10-04) LEMLEM DESALEGN
Most of Ethiopian construction projects are affected by time and cost performance problems. This research was conducted in an attempt to identify major factors for such problems in the typical environment of Ethiopia Tigray region in case of Abi Adi town. The main objective of this study was to assess the performance of public construction projects in Abi Adi town with respect to their time and cost. And under this, specific objectives were also drown: To evaluate the performance of public construction projects in relation to project time and cost, to identify the factors influencing public construction projects to perform the construction project as per required time and cost in Abi Adi town. Quantitative research method was used to collect the data and questioners were prepared and distributed to the three professional bodies of the construction projects, such as owners, consultants, and contractors. To analysis the data collected from the respondents, performance index and relative important index statistical methods were used. The result of the finding indicated that, high number of time and cost performance of the projects was below target and poor performance. The study has identified client, consultant, contractor and external environment related factors that resulted on time overrun: such as, delay to payment and financial problem, delay to deliver the site, poor communication and coordination, absence of consultant site staff, poor skills and experience of labor, Poor site management and lack of site contractors’ staff, lack of equipment and tools on the market, poor economic condition, Lack of materials on the market and Delay in obtaining permits from municipality. The cost performance factors were; Inadequate project preparation, planning and implementation delay in construction, technical incompetence and poor organizational structure, delays in decisions making by government, failure of specific coordinating bodies, supply of raw materials and equipment by contractors, and resources constraint such as: funds foreign exchange, power associated auxiliaries not ready. Finally the main stakeholders of the construction projects should improve problems related them and use resource effectively and efficiently
Voltage Control of DC-DC Boost Converter Using Lyapunov Rule Based Model Reference Adaptive Controller
(Mekelle University, 2024-10-24) : Mebrahtu Ngusse
The switched mode DC-DC converters are the simplest power electronic circuits that facilitate the conversion of electrical voltage from one level to another through a switching process efficiently. DC-DC boost converters are utilized for step-up voltage in various applications. The output voltage of boost converter has, oscillation, overshoot, undershoot, and steady-state error. PID controllers have been usually applied to the converters because of their simplicity to obtain the desired voltage. But, PID controller could work well in one operating condition and cannot continuously adapt the changes in the process dynamic. To overcome this problem an advanced controller is required. The proposed Lyapunov Rule Based MRAC is adaptive and non-linear controller designed to overcome the uncertainties and nonlinearities for DC-DC boost Converter under Continuous Conduction Mode (CCM) operating condition. Using MATLAB/Simulink the performance of the proposed Lyapunov rule based MRAC is compared with that of the PID controller based on the dynamic response of the system. Using PID controller, overshoot and settling time have been improved by reducing from 67.5229% to 7.7717% and 0.6985 Sec to 0.277 Sec respectively. In the case of the proposed controller (Lyapunov rule based MRAC), overshoot, settling time, and undershoot have been improved by reducing from 67.5229% to 4.5993%, from 0.6985 Sec to 0.1458 Sec, and from 0.0036% to 0.0% respectively. To test the performance of the DC-DC boost converter, it is assumed that, the input voltage has been decreased and increased from its operating point by 25% and 41.67% respectively. Also the load resistance is assumed to be decreased and increased from its operating load resistance by 25% and 20% respectively. An external disturbance is applied to the system to check how the controller handles to uncertainties and PID controller has shown deviation from the desired value but, the controller MRAC maintained the desired value.
Medium Voltage Distributed Network Performance Optimization by Reliability Centered Maintenance Prioritization of Distributed Feeders and DG Integration
(Mekelle University, 2024-10-25) Rahwa Berhane
In today's world, virtually every human activity relies on electricity, either directly or indirectly. Reliable electric power is essential for our daily activities, and this power is delivered through a distribution network. However, numerous issues prevent the continuous supply of electricity to end-users. The main problem on the distribution network are lack of planned preventive maintenance, improper feeder size selection, over load and lack of DG. To address these issues, this work employs a reliability-centered prioritization of feeders for maintenance and integrate a solar PV system to the distribution network using the Electrical Transient Analyzer Program (ETAP) to improve the reliability and availability of electric power. A comprehensive reliability analysis for identifying a feeder R5 as a case study sample, making it the case study for Reliability improvement. By integrating, a DG in the selected feeder results a significant improvement in reliability indices. The System Average Interruption Duration Index (SAIDI) was reduced from 735.43 hours/customer/year to 369.413 hours/customer/year, and the System Average Interruption Frequency Index (SAIFI) decreased from 293.259 per year to 200.30 per year. These reductions represent decreases of 49.77% and 31.7%, respectively. Furthermore, the Expected Energy Not Supplied (EENS) dropped from 46,107.5 MWh to 23106.71 MWh, and the Expected Outage Cost (ECOST) decreased from $2,019,508.5 to $1,012,073.898, indicating an improvement in cost-worth reliability indices and the network's revenue. The reduced reliability indices demonstrate the enhanced performance of the distribution network from a reliability perspective. Implementing a reliability-centered maintenance for the feeders in the conventional distribution network would also improve the reliability of Mekelle city distribution network.
Investigation of Ceramic Tile Waste as Partial Replacement of Cement in concrete
(Mekelle University, 2024-11-08) Tsegay Kassahun Gebreegzabihe
The construction industry's rapid growth coupled with increasing environmental concerns and necessitates sustainable practices. The study investigates grinded ceramic tile wastes as a partial replacement for cement for C-30 concrete grade having an aim to feel material scarcity and enhance sustainability in the construction industry. After the concrete ingredients test, mix design of C-30 concrete grade was prepared and concrete cube specimen with 0%, 5%, 10%, 15%, 20%, 25% and 30% of ceramic tile wastes in place of cement were casted, cured and tested for compressive and flexural strength. The experimental test results have revealed, an increase in the proportion of grinded ceramic tile waste in concrete production decreases workability. In terms of strength, both compressive and flexural strengths initially increased with ceramic tile waste, peaking at 10% replacement with a compressive strength of 40.26 MPa and a flexural strength of 4.31 MPa at 28 days. Beyond 10%, both strengths declined indicating that while moderate ceramic waste enhances concrete strength but excessive replacement negatively impacts performance. And the cost analysis revealed that incorporating ceramic waste significantly reduces the cement cost. It can therefore be concluded that in areas where cement scarcity or high costs are prevalent, the partial replacement of cement with grinded ceramic tile waste in concrete is a viable and sustainable alternative. The use of ceramic waste at optimal levels can improve strength properties and offers significant cost advantages while contributing to waste management and reducing the environmental impact of construction activities.
Design and Optimization of Bamboo/Glass Fiber Reinforced Epoxy Composites for Sustainable Wall Panel Application
(Mekelle University, 2024-11-12) Tedros Tilahun
Estimating the angle of arrival (AoA) of a coming signal can accomplished using various methods. In most cases algorithms are used for such purposes. However, algorithms are naturally complicated and expensive, and also cause a degradation in system performance. Therefore, other methods such as, 1800-hybrid rat race (HRR) coupler can be applied for effectively estimating the AOA of a coming signal. In this thesis work, an 1800 HRR coupler integrated with a 2x1 closely-spaced patch antenna array and a negative permeability metamaterial was studied for estimating AoA of a coming signal. The 1800 HRR was made up of a ring metallic sheet integrated with four additional branches placed at the edges of it. It operates at 10 GHz so as to make compatible with the 2x1 patch antenna array’s operating frequency. The simulation results show, the 1800 HRR coupler is characterized by 00- phase at the sum (Σ)-port while 1800 phase shift at the difference (Δ) port at the given operating frequency. In order to integrate with the 1800 HRR, a 2x1 array patch antenna with an inter - element distance of 0.6λ (where λ is the operating wave length) was designed. The antenna array workes at 10GHz with a maximum simulated gain of 8.824 dB while keeping the mutual coupling to a minimum of -23 dB. To further achieving miniaturization, the inter-element distance reduced to 0.4λ. The simulation result shows a resonance at 10 GHz frequency and maximum gain of 7.8 dB while the mutual coupling increased to -9 dB. The 2x1 patch antenna array with inter - element distance of 0.6λ -1800 HRR coupler system was able to estimate the AoA of the received signal from 00 to 190 with error of less than 50. While with a reduced inter – element distance to 0.4λ, the system was able to estimate signals from 00 to 500 with error of less than 50. Upon integrating split ring resonator (SRR) met materials, mutual coupling reduced to -15.6 dB without affecting the AOA of the system. This study was able to estimate AOA in a wide range of an incoming signal while keeping the inter – element distance smaller. The proposed design can be applied in radar system applications where accurate estimation of AOA of an incoming signal is needed such as in target tracking, surveillance, and navigation missions.
Design and Experimental Evaluation of passive Solar Still under hottest and driest climate condition of Ethiopia: A case of lake-Afdera saline water
(Mekelle University, 2024-12-25) Mohammed Ahmed Yasin
Access to potable water remains a critical challenge globally, particularly in arid regions such as Ethiopia's Afar Region, where groundwater is often limited or contaminated with high levels of fluoride and salinity. This study investigates the design and performance of passive solar stills for desalinating saline water from Lake Afdera under extreme climatic conditions. The objective was to enhance the productivity of conventional single-slope, single-basin solar stills by incorporating black volcanic rocks as thermal energy-absorbing materials. Two solar still configurations a conventional design and a modified design with black volcanic rocks were constructed and experimentally evaluated over two days in Afdera. Parameters such as ambient temperature, water temperature, and hourly yield were recorded. To validate the results, the modified still was later tested under different environmental conditions at Mekelle University using thermocouples, PicoLog software, a pyranometer, and measuring jars for precise data collection. Results showed that the modified solar still significantly outperformed the conventional still in water yield, producing 3,482 ml and 3,800 ml over two days compared to 1,920 ml and 1,780 ml, respectively. It also demonstrated improved night-time performance, yielding 890 ml versus 340ml, due to better heat retention from the black rocks. Correlation analysis from the Mekelle validation indicated strong relationships between water yield and solar radiation (r = 0.60), rock temperature (r = 0.96), internal temperature (r = 0.85), and ambient temperature (r = 0.83). The modified system achieved 32.87% higher efficiency in Afdera than in Mekelle, highlighting the role of environmental conditions. The findings confirm that integrating black volcanic rocks into solar still design enhances efficiency and output, offering a cost-effective and sustainable desalination solution for arid, high radiation regions like Afar.