Mekelle University Institutional Repository
Discover scholarly works, research outputs, and institutional publications.
The Mekelle University Institutional Repository is a digital collection of scholarly and research outputs created by the university's faculty, students, and researchers. This repository provides open access to a wide range of materials, including articles, theses, dissertations, conference papers, books, and more."
By making our research available, we aim to
- Increase the visibility and impact of research conducted at Mekelle University.
- Promote knowledge sharing and collaboration within the academic community.
- Preserve and disseminate valuable scholarly works for future generations
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- A central archive for Mekelle University’s institutional abstract books from academic and research conferences.
Recent Submissions
DEVELOP A Bi-DIRECTIONAL ENGLISH - NUER MACHINE TRANSLATION USING DEEP LEARNING APPROACH
(Mekelle University, 2024-12-28) Lemlem Gebremedhin
The advancement of deep learning has revolutionized natural language processing, with machine translation playing a pivotal role in bridging linguistic barriers. This research focuses on developing a bi-directional English-Nuer machine translation system using deep learning techniques. The primary challenge is the lack of linguistic resources for the Nuer language, hindering its technological representation and global accessibility. To address this, the study constructed a parallel corpus of 46,134 English-Nuer sentence pairs and employed models such as GRU, Bi-GRU, LSTM, LSTM with attention and transformer mechanisms. The findings revealed that the Transformer model achieved superior BLEU scores compared to the other architectures, scoring 0.2567 for Nuer-to-English and 0.2431 for English-to-Nuer translations. The results highlight the potential of the proposed deep learning-based machine translation for low-resource languages. As future work, the researcher highlights to explore integrating speech-to-text and textto-speech capabilities to enhance usability.
Design and Optimization of a Hybrid Polyester Composite for Bus Roof Plates Using Jute and Reused PET Fiber Reinforcement
(Mekelle University, 2025-05-19) Natnael Abera
The automotive sector faces rising fuel consumption and pollution due to the increasing vehicle numbers. To mitigate these challenges, lightweight materials have become imperative to diminish the weight of automotive components. Additionally, addressing the pervasive issue of plastic pollution necessitates innovative solutions, such as recycling or reusing the primary plastic pollutant, polyethylene terephthalate (PET). This study tackles two interconnected issues: reducing vehicular weight through material substitution and mitigating plastic waste by reusing PET from discarded water bottles. The main objective of this study is to design and optimise a hybrid polyester composite material for bus roof plates for the modified ISUZU NPR71 4570cc, utilizing jute and reused PET fibers as reinforcement. Samples were prepared using the hand lay-up method, with fiber-to-matrix weight fractions ranging from 40% to 60%. Five laminates were created, incorporating alkali-treated jute fibers to enhance interfacial adhesion. Through a series of experimental tests, the tensile, compressive, flexural, impact strengths, density, and water absorption rates were conducted. The TOPSIS method was applied to assess and evaluate the properties of prepared laminate samples. Results indicate that the P-J-J-P orientation of NaOH treated jute fiber stands out as the optimal choice. The NaOH-treated jute fiber reduces water absorption by 47% (1.13% compared to 2.13% for untreated jute). A hybrid composite with a PJ-J-P layup and a 0°-90°-0° orientation was used to design a bus roof plate, optimised using Hyper Works-Optistruct and validated through re-analysis with ABAQUS. The optimised jute/PET hybrid polyester composite roof plate achieved a 34.58% weight reduction compared to a mild steel plate, decreasing from 210.38 kg to 137.63 kg, and saved 0.2765 litres of fuel per 100 km. This demonstrates that jute/PET hybrid polyester composites can effectively replace steel structures, offering significant environmental benefits and fuel savings without compromising performance or vehicle load capacity.
DESIGN, DEVELOPMENT, AND EXPERIMENTAL INVESTIGATION OF A PORTABLE MULTI-BLOCK MAKING MACHINE
(Mekelle University, 2025-05-19) Kibrom Gidey
This thesis presents the design, development, and experimental investigation of a Portable MultiBlock Making Machine, aimed at overcoming the limitations of existing single-block and multiblock machines. The innovative design combines portability with high output efficiency and reduced energy consumption, making it suitable for small to medium-scale manufacturers in diverse construction environments. The developed prototype demonstrates the capability to produce five hollow cement blocks simultaneously, adhering to industry standards for block quality and structural integrity.
Finite Element Analysis (FEA) was employed to validate the structural reliability and production efficiency of the machine. Key findings from the FEA indicate that stress distribution, displacement, and strain levels remain well within acceptable limits. The von Mises stress analysis confirms that all components experience stress values significantly below the yield strength of ASTM A36 mild steel, ensuring that the machine operates within the elastic deformation range, thereby preventing permanent failure. Additionally, the displacement analysis reveals minimal deformation across all structural components, indicating robust mechanical stability during operation. The strain analysis further validates effective stress distribution, demonstrating that material selection and design choices mitigate localized strain concentrations, enhancing overall durability.
The Factor of Safety (FOS) analysis provides a minimum safety margin of 1.5, reinforcing the design's compliance with industrial safety standards and its ability to withstand operational loads. The successful fabrication and testing of the prototype confirm that the Portable Multi-Block Making Machine offers a high-output, energy-efficient alternative to conventional block-making methods, significantly improving productivity and lowering operational costs.
Looking ahead, future enhancements should focus on fatigue analysis, structural reinforcement in high-stress areas, and optimization of mold alignment to further boost efficiency and lifespan. The integration of automated control systems and renewable energy sources could also enhance sustainability and operational flexibility.
Experimental Characterization and Finite Element Analysis of Jute and Glass Fiber Reinforced Epoxy Composite Material for Structural Automotive Components.
(Mekelle University, 2025-05-19) Haftom Hailemichael
Using of fiber-reinforced composite materials is rapidly advancing in the automotive and aerospace industries due to their superior properties, including lightweight, high strength-to-weight ratio, high impact strength, corrosion resistance, design flexibility, and dimensional stability. Traditionally, vehicle bodies have been constructed from heavy metals like steel, increasing vehicle weight and fuel consumption. This study focuses on enhancing the mechanical properties of Jute/Glass Fiber reinforced epoxy composites for automotive body applications.
The research evaluates tensile, compression, impact, and flexural strengths of unidirectional jute and glass fiber composites by varying fiber weight ratios, orientation angles, and stacking sequences. Experimentation followed ASTM standards, and the composite car bonnet was designed and analyzed using Classical Laminate Theory and optimization via Opti-Struct in Altair Hyper Mesh 2019.
Results indicated that a 50/50 weight ratio of jute to glass fibers with unidirectional orientation offered the best mechanical properties. Additionally, incorporating ±45° fiber orientations enhanced impact strength in both lateral and transverse directions. The bonnet design optimization led to a 67% weight reduction compared to conventional steel bumpers, resulting in an average fuel savings of 0.0034 L/100 km.
Thermal analysis using FEM Ansys showed that the composite bonnet had lower thermal conductivity and heat flux, with higher temperature distribution at the edges due to constraints. The thermal stress remained within safe limits, indicating no immediate failure risk.
In conclusion, the hybrid composite material with Jute/Glass fibers can effectively replace traditional steel Bonnet, offering significant weight reduction and fuel efficiency improvements without compromising safety.
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.