ASTU ETD

Adama Science and Technology University Library Electronic Theses & Dissertations (ASTU- ETD) is a new digital institutional repository system that collects, preserve and distribute the scholarly output of the university, mainly postgraduate Electronic Thesis and Dissertation (ETD), articles, proceedings. The system is dedicated to help users to find all the information they might require in order to format and successfully submit their graduate thesis, dissertation and publications electronically. The user friendly web interface enables to maximize & optimize the resource sharing among ASTU different Colleges.

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Recent Submissions

Harnessing Chromogenic Bacteria for Eco-Friendly Textile Dyeing: Pigment Production and Process Optimization
(ASTU, 2026-01)
Birhanu Zeleke
Microbial pigments are emerging as sustainable alternatives to synthetic dyes due to their environmental compatibility and potential for circular bio-economy applications. This study focused on the identification of potent pigment-producing bacterial isolates, the use of agro waste substrates as low-cost substrates, and the optimization of culture parameters to enhance pigment yield. The study systematically explored pigment-producing bacterial isolates from environmental samples, employing morphological, biochemical, and MALDI-TOF analyses for identification. Eco-physiological tolerance was assessed using the one-variable-at-a-time approach, while culture optimization was conducted through Plackett–Burman Design followed by response surface methodology. Agro-waste extracts as low-cost substrates were evaluated via optical density measurements, and pigments were extracted using organic solvents. Pigments were characterized using UV-Vis spectroscopy, LC-MS, and ATR-FTIR. The pigments' stability under varying stressor conditions was assessed by monitoring absorbance at their characteristic wavelengths. Fabrics dyeing were conducted using immersion technique. Dye exhaustion and fixation to fabrics were evaluated via absorbance method after washing and exposure to sunlight. From purified colonies on streak plates, six isolates; namely: Acinetobacter sp., Exiguobacterium aurantiacum, two Kocuria spp. (from different samples), Micrococcus luteus, and one unidentified strain, exhibited chromogenic potential. Among the chromogenic isolates screened, Micrococcus luteus exhibited the highest pigment yield (1.47 g/L) under orange-waste extract cultivation, likely due to the isolate's inherent carotenoid biosynthetic capacity, stress tolerance, and efficient substrate utilization. Optimization of pigment production by Exiguobacterium aurantiacum using tomato-waste extract revealed that agitation rate, pH, and yeast extract concentrations were the most significant factors influencing culture growth (p<0.001), leading to 1.6-fold yield increment compared to un-optimized conditions. The characteristic UV-Visible absorbance peaks (400 550 nm) indicated the pigments are likely carotenoid compounds with functional group signatures (O–H, C–H, C=C, C=O) from infrared spectra analyses. The LC-MS analyses further resolved pigment mixtures, provided molecular weights and fragmentation patterns, indicating pigment heterogeneity. Stability assays of Micrococcus luteus pigment indicated susceptibility to oxidative and thermal stress, while dyeing trials demonstrated vibrant and uniform coloration with moderate fixation on fabrics. While microbial pigment production has been widely reported, existing studies predominantly rely on synthetic media. The present study is fundamentally novel, integrating systematic screening, agro-waste valorization, and multivariate statistical optimization, marking the first such effort in Ethiopia. The findings highlight Micrococcus luteus as a robust candidate for scalable, eco-friendly pigment production under low-cost sustainable culture conditions. The findings highlight the feasibility of low-cost, eco-friendly microbial pigments for industrial applications as promising alternatives to synthetic dyes.
Synthesis of Vanadium Oxide (V₂O₅) Nanoparticles for Degradation of Methylene Blue Dye
(ASTU, 2025-06)
Demise Sorie
Vanadium pentoxide (V₂O₅) nanoparticles were successfully synthesized using ammonium metavanadate as a precursor and Laggera tomentosa leaf extract as a natural reducing agent through a sol–gel method. The obtained nanoparticles were characterized to investigate their morphology, optical properties, functional groups, and structural features using ultraviolet visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FT–IR), Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The photocatalytic performance of the V₂O₅ nanocomposite was evaluated under visible light irradiation for the degradation of methylene blue (MB), with optimization of both catalyst dosage and contact time.
Exploring Performance of Metamaterial Emitters for Applications of Energy Harvesting and Gas Sensing: Modeling and Simulation Approach
(ASTU, 2026-01)
Gemechis Mathewos
This dissertation presents a theoretical investigation into the spectral performance of a multilayer and grating metamaterial composed of tungsten (W) and Aluminumnitride (AlN), hafnium dioxide (HfO₂) designed to enhance thermophotovoltaic (TPV) energy conversion efficiency. Utilizing advanced electromagnetic simulations based on Maxwell‘ s equations, the study explores the optical properties of a W/HfO₂/W metamaterial structure, focusing on its ability to produce high emissivity within the wavelength range of 1.5 to 2.0 μm optimal for interfacing with InGaAsSb TPV cells. The results demonstrate that the metamaterial achieves an average emissivity exceeding 96%, with a peak of 99.9%, primarily driven by resonant mechanisms such as surface plasmon polaritons and magnetic polaritons. The design exhibits polarization independence and maintains high performance across incident angles of 0° to 60°, indicating robustness for practical applications. Furthermore, the study assesses the impact of material selection and structural parameters on emissivity characteristics, emphasizing the potential of engineered metamaterials to significantly improve thermal radiation control. The findings suggest that the proposed W/HfO₂/W metamaterial has promising implications for advancing high-efficiency TPV systems, contributing to sustainable energy solutions through optimized thermal emission engineering. Additionally, it presents the design and simulation of a terahertz metamaterial-based gas sensor aimed at detecting toxic atmospheric gases such as ozone (O₃) and nitric oxide (NO). Utilizing a metal-dielectric metal (MDM) structure composed of tungsten and hafnium dioxide, the sensor exhibits dual resonance frequencies with absorption rates approaching 99%. Finite Element Method (FEM) simulations demonstrate high sensitivity to variations in refractive index, with sensitivities up to 4.58 THz/RIU and a figure of merit exceeding 11.82/RIU. Distinct resonance shifts corresponding to different gases affirm the sensor‘s potential for real time, selective gas detection. The findings underscore the effectiveness of metamaterials in environmental monitoring applications and lay the groundwork for developing practical, hi gh-performance gas sensors for air quality assessment.
Strategic Mitigation Of Cost Overruns In Road Construction: An Integrated Ahp-Dematel Framework For Arsi Zone, Ehiopia
(ASTU, 2026)
Girma Geleta
Cost overruns are a chronic and pervasive challenge in the global construction industry, posing a significant threat to the successful delivery of critical infrastructure, particularly in developing nations like Ethiopia. Existing research often identifies numerous contributing factors but frequently fails to analyze their complex interrelationships, limiting the development of effective, context-specific mitigation strategies. This thesis aims to address this gap by developing and validating a data-driven strategic framework for mitigating cost overruns in road construction projects within the Arsi Zone. The study employs an integrated Analytic Hierarchy Process (AHP) and Decision-Making Trial and Evaluation Laboratory (DEMATEL) approach. Data was collected through structured surveys with a purposively selected panel of 12 experienced industry experts representing clients, contractors, and consultants. The analysis was conducted using MS Excel for data organization and Python programming for the core AHP and DEMATEL computations. The AHP results identified Ineffective Right-of-Way Management as the single most critical factor, with a global importance weight of 29.28%, highlighting its status as a systemic bottleneck. The DEMATEL analysis further uncovered the underlying causal architecture, distinguishing foundational drivers, such as Political Instability and Interference and Weak Capacity of Local Firms, from their highly visible but largely symptomatic effects, like Financial Difficulties of Contractor. The novelty of this study lies in the integrated analysis, which reveals a critical strategic paradox: foundational drivers perceived as having low importance by stakeholders are, in fact, the most influential root causes. This disconnect explains the industry's tendency toward reactive firefighting of symptoms rather than proactively addressing root causes. The final validated framework translates these findings into actionable recommendations for key beneficiaries, including the Ethiopian Roads Authority, contractors, and supervising consultants, providing a clear roadmap to shift from a reactive to a proactive, cause-driven management paradigm. The primary conclusion is that effective cost overrun mitigation requires prioritizing interventions that target these foundational drivers to achieve sustainable and long-term improvements in project cost performance.
Key Practices For Effective Right-Of-Way Acquisition Management In Construction Projects: Hierarchical Importance And Interrelationships
(ASTU, 2026)
Sebona Bekena
Right-of-Way acquisition is a major challenge in Ethiopian road construction projects, especially in the Arsi Zone, where delays caused by compensation disputes, weak stakeholder coordination, and inadequate planning often results cost and time overruns. To identify solutions for these challenges, the study focuses on assessing and ranking key management practices for effective Right-of-Way acquisition by combining the Analytic Hierarchy Process and Interpretive Structural Modeling. Analytic Hierarchy Process was used to prioritize practices based on their perceived importance, while the Interpretive Structural Modeling method assessed their interrelationships. For this study Primary data were collected from 25 experts and practitioners directly involved in road construction, especially in Right-of-Way management, through structured questionnaires. The first Analytic Hierarchy Process results ranked Conduct pre-acquisition public involvement, provide fair, reasonable, and adequate compensation, and Encourage property valuation based on current market values as the top three critical management practices. The Interpretive Structural Modeling analysis showed that creating legally binding policies that require stakeholder coordination, providing training for all levels of Right-of-Way staff, and using modern software systems to manage Right-of Way activities are highly influential drivers of other practices. When integrating both analyses through quadrant analysis, eight practices fell into the Keep Up the Good Work quadrant, indicating high importance and strong influence. These management practices include early public involvement, fair and timely compensation, transparent valuation, ongoing communication, legal reform, dispute resolution support, staff capacity building, and adoption of digital Right-of-Way management tools. By combining these methodologies, this study provides a comprehensive framework to guide contractors and road authorities in Ethiopia to address Right-of-Way related challenges and improve the success rate of road construction projects