AAU Institutional Repository (AAU-ETD)
Addis Ababa University Institutional repository is an open access repository that collects,preserves, and disseminates scholarly outputs of the university. AAU-ETD archives' collection of master's theses, doctoral dissertations and preprints showcase the wide range of academic research undertaken by AAU students over the course of the University's long history.
How to Submit Your Work
The repository contains scholarly work, both unpublished and published, by current or former AAU faculty, staff, and students, including Works by AAU students as part of their masters, doctoral, or post-doctoral research
- All AAU faculty, staff, and students are invited to submit their work to the repository. Please contact the library at your college.
You may contact digirep@aau.edu.et.with any questions about the repository
Colleges,Institutes in AAU-ETD
Select a college,institute to browse its collections.
Recent Submissions
Investigating the Effect of Gluten Content on the Pasting Properties of Wheat Obtained from Different Botanical Sources and Its Impact on Bread Quality
(Addis Ababa University, 2024-09)
Wheat is a cereal grain that comes in different varieties and is widely consumed worldwide. The objective of this study was to investigate the effect of gluten on functional and pasting properties of flour associated to its botanical sources. The study examined the proximate, functional, and pasting properties of three types of botanically varied wheat flours. Five wheat flour samples namely Arsi Wheat flour (AWF), Bale Wheat flour (BWF), Dodola Wheat flour (DWF), Mixed Wheat flour (MWF), and Supermarket Wheat flour (SWF) were developed and evaluated using the standard method. The study showed that the gluten content of DWF was 26.73 ± 0.23% on a wet basis which is the highest among the samples. Whereas, SWF has the lowest gluten content, i.e., 21.44±0.12%. On the other hand, the crude protein content of the BWF sample was found 12.620±0.05% showing the highest among all flour samples. Besides, the SWF sample showed higher water absorption capacity whereas MWF has highest water solubility. The pasting temperatures of AWF (89.1⁰C), BWF (87.25 ⁰C) and DWF (88.8 ⁰C) which was almost lied on similar ranges. However, the BWF sample has a significantly higher final viscosity than AWF and DWF at P< 5% level. It was observed that all wheat flour samples have similar functional groups such as hydroxyl groups (O-H), aliphatic hydrocarbons (C-H), carbonyl groups (C=O) from ketones or aldehydes, and ethers or esters (C-O). In terms of bread quality, bread baked from BWF sample has the best color, texture, taste, flavor, odor, mouth feel and overall acceptability. In addition, bread based on BWF sample got better protein content. The alkaline water retention capacity of the bread samples was decreased as the storage time increased in contrast, the staling rate of the bread samples was increased as the storage time increased. The study concluded that wheat botanical origin influences gluten content which in turn affect the dough properties (elasticity, heat tolerance, leavening) and bread quality (crust, color, sponginess).
Energy Management of Three Wheeler Hybrid Electric Vehicle by Using Model Predictive Controller
(Addis Ababa University, 2024-08)
In response to environmental issues and declining global crude oil reserves researchers and automobile
manufacturers are exploring novel vehicle technologies. Hybrid Electric Vehicles (HEVs) reduce
fuel usage and greenhouse gas emissions. The transportation sector consumes around 66% of global
oil consumption, with small passenger cars and trucks accounting for 50%.
For meeting future energy demands and reducing pollution a power-split hybrid electric car is a
possible solution . It combines features of both conventional and electric vehicles. Energy can be
managed optimally because it comes from two subsystems: the engine and the battery. This thesis
presents a model predictive control approach with constraint handling that outperforms previous
strategies for efficient energy management of hybrid electric vehicles. A comprehensive mathematical
model of a three wheeler Auto Rickshaw power split hybrid electric car is created, including the
engine, planetary gear, motor/generator, and battery.
The presented model utilizes an interior-point optimizer-based nonlinear predictive control approach
with operational limitations and a cost function. The goal is to reduce fuel usage and keep
the battery’s charge within predefined limitations. The generated model was simulated in MATLAB,
including motor, generator, engine speed, and battery SoC. The proposed MPC results for the
HWFET(modified) and EUDC(modified) cycles show specific fuel consumption of 0.5162 and 0.5817
liters/100 km, respectively. The ADVISOR 2003 rule-based method yields 1.00 and 1.1 liters/100 km
for the HWFET(modified) and EUDC(modified) cycles, respectively, supporting these findings.The
suggested MPC improves specific fuel consumption by 48.39% and 47.12% in HWFET(modified)
and EUDC(modified) drive cycles, respectively. So MPC based three wheeler power split HEVs
would play a significant role to significantly lower fuel consumption and environmental pollution and
foreign currency to import fuel.
Accuracy Assessment of digital parcel map for Second-Level Land Demarcated Parcel in Case of Guahgot Kebelle, Eastern Tigray
(Addis Ababa University, 2024-08)
Rural cadastral mapping in Ethiopia has significantly improved since 2003, when a parcelbased
demarcation system replaced the traditional method of registering parcels through written
documents. This rural cadastral map aims to comprehensively document the land’s history and
certify its usage types, including private, communal, state-owned, leased investment lands, and
other holdings. During this process, parcels are delineated using printed Orthophoto images
created from Remote Sensing or photogrammetric data.
This study examines the horizontal positional accuracy and validation of the digital parcel map
using in-situ total station measurements and direct digitization from digital orthophotos. The
digital parcel map’s horizontal accuracy is evaluated according to ASPRS standards and
general boundary criteria, computing the Root Mean Square Error (RMSE) independently for
both datasets and the RMSE in radial linear directions using thirty checkpoints. Additionally, the
validation of the digital parcel map is based on general boundary principles.
The planimetric accuracy of the digital parcel map for selected sample parcels is assessed using
total station measurements, determining the horizontal linear RMSE in the radial direction
errors for these parcel corners are 1.697 meters and 1.633 meters, respectively. Furthermore,
this study validates the area and perimeter of the digital parcel map using data collected through
total station surveys and digital orthophotos. During the validation of area for total parcels
within the kebelle, 8.21% (446 parcels) fall outside the general boundary standard (with errors
exceeding 17%) when compared to field measurements. Additionally, the validation of parcel
perimeters process reveals differences ranging from 3.61% to 0.48% for distances of 135 meters
and 270.547 meters, respectively, when using the total station. Comparing with digital
orthophoto measurements, the differences range from -7.41% to 0.14% for the same distances.
Based on the study findings, the second-level land demarcation process requires modernization
to align with ASPRS fixed boundary standards. To achieve better accuracy in digital parcel map,
the Rural Land Administration should prioritize the exclusive use of digital orthophotos for
large-scale map production.
Development and Using Carbon Fiber Reinforcing Polymer to Strengthen The Flexural Capacity of Damaged Post-Tensioned Beams
(Addis Ababa University, 2024-10)
Post-tensioning is a type of pre-stressing in which high-strength steel strands or bars;
commonly referred to as tendons, are used to reinforce (strengthen) concrete or other
materials. Carbon ber-reinforced polymers on the other hand are incredibly light and
strong ber-reinforced plastics that are used to enhance concrete structures by bonding
the polymer to the concrete member.
Damage to structural members can occur due to di erent reasons in various real-world
applications. Similarly, post-tensioned members can also be subjected to damage due to
various reasons, such as accidental cutting or drilling into tendons, failures in anchorage
and dead end zones resulting from issues like insu cient anti-burst reinforcement, mis-
alignment of the anchor, and improper material utilization. These problems can lead to
the loss of prestressing force in post-tension strands, which in turn can decrease the load
carrying capacity of the elements, particularly their exural capacity. This thesis paper
investigates the potential of Carbon Fiber-Reinforced Polymer (CFRP) strengthening in
enhancing the exural capacity of damaged post-tensioned concrete beams.
Employing an experimental program, the study compares the performance of control
beams to beams strengthened with varying CFRP layers. Results demonstrate a sig-
ni cant increase in exural capacity, averaging 41.5% per CFRP layer, highlighting the
e ectiveness of this strengthening technique. How varying amount of post tensioning
and CFRP wraps a ect cracks and delamination patterns of carbon ber were also stud-
ied and discussed in detail. Further exploration into alternative ber types and testing
con gurations is recommended. .
Enhancing Railway Track Structural Condition Assessment Using Multi-Criteria Decision-Making Method
(Addis Ababa University, 2024-10)
The safety and reliability of railway infrastructure are dependent on diligent maintenance and
inspection practices. A well-organized maintenance approach is imperative in ensuring the
safety and reliability of a railway system. One of the most important aspects of railway
maintenance is the detection and monitoring of track defects, which can lead to catastrophic
failures if left unaddressed. While existing techniques can be beneficial in certain respects,
they are incapable to provide a comprehensive view of the structural conditions of railway
tracks, compromising ride safety and quality. This research addresses this gap by developing
a model for railway track structural condition assessment using Multi-Criteria Decision
Making (MCDM).
Leveraging an extensive literature review the model assigns weights to key track components
and defect categories through the Best-Worst method. Mamdani Fuzzy logic integrates diverse
defect criteria and translates qualitative severity evaluations into numerical scores. The
analysis reveals rails (48.16%) as the most critical component, followed by sleepers (21.05%).
Within rail defects, transverse fissures hold the highest weight (43.75%).
Validated through a case study, the model demonstrates strong agreement with actual results.
A user-friendly application built on FlutterFlow facilitates detailed track condition
assessments, encompassing individual defect categories, component health, and overall track
structure status.
This model empowers data-driven decision-making for railway authorities, enabling them to
prioritize and address track issues effectively. The MCDM approach provides a structured
framework for maintenance planning. Ultimately, this research aims to refine railway track
infrastructure management through a structured and data-driven decision-making process.