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Cessna 172 G1000 Aircraft Airfoil Optimization Using Particle Swarm Optimization Method Applying a Direct Airfoil Design Approach to Obtain the Maximum Lift-to-Drag Ratio

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Russian Aeronautics 2023年第4期66卷 789-798页

作者： Zeleke, Dinku Seyoum Asfaw, Abdurehman Yimer Bizuneh, Bethel Lemma Michael, Leul Walelign Addis Ababa Science and Technology University Addis Ababa16417 Ethiopia

Abstract: The paper focuses on optimizing the airfoil shape for the Cessna 172 R G1000 training aircraft in order to get the best lift-to-drag ratio without increasing the applied wing current aerodynamics moment. In order to achieve good aerodynamic performance, a swarm-based approach with shape parametrization is used. Particle swarm optimization is used to examine the optimal solution through evolution, whereas XFOIL is used as the main flow field solver. Airfoils are generated continuously using B-splines airfoil parametrization based on the criteria of the particle swarm optimization algorithm until the desired target has been achieved. After the algorithm has attained the desired goal, more shape smoothening is required, which is accomplished using XFOIL. Finally, ANSYS Fluent and a k–Ε solver are used to test the airfoil. The major emphasis of the flow simulation is to see if there is flow separation at higher angles of attack and to see if XFOIL results in a more robust solver. Even in a very limited space, the data show a 15% increase in lift-to-drag ratio in cruise settings. © Allerton Press, Inc. 2023.

关键词： Airfoils

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Self-healing performance of normal strength concrete with Bacillus subtilis bacteria

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Journal of Building Pathology and Rehabilitation 2024年第1期9卷 1-13页

作者： Zamba, Duresa Dubale Mohammed, Tesfaye Alemu Department of Civil Engineering Addis Ababa Science and Technology University Addis Ababa Ethiopia Construction Quality and Technology Center of Excellence Addis Ababa Science and Technology University Addis Ababa Ethiopia

The use of bacteria to improve the mechanical and durability properties of concrete was investigated in this study. B. subtilis bacteria were incorporated into normal strength concrete at a concentration of 10⁸ cells/ml. A total of 66 concrete specimens were cast and tested for mechanical and durability properties (compressive strength, flexural strength, UPV, water absorption, acid resistance, and salt resistance) at 7, 14, 28, and 56 days. Cracked specimens were also examined using 3D optical microscope until cracks were healed. The results showed that the addition of bacteria to concrete significantly improved its mechanical and durability properties. The compressive, flexural, and UPV values of concrete with bacteria increased to 19.55%, 15.25%, and 5.40%, respectively, compared to the control group at 28 days of curing. At 56 days of curing, the acid and salt resistance of concrete with bacteria increased to 11.38% and 18.78%, respectively. Examination of the cracks in the bacterial concrete using a 3D optical microscope revealed a large white crystalline deposit was formed that almost filled the surface of the crack. This is due to the B. subtilis bacteria producing calcite precipitation, which fills concrete cracks. Overall, the results of this study showed that the use of B. subtilis bacteria can significantly improve the mechanical and durability properties of concrete. This makes bacterial concrete a promising material for use in a variety of applications, such as infrastructure, construction, and civil engineering. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Bacterial concrete Calcite precipitation Durability properties Mechanical properties Self-healing

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Strength and Durability Evaluation of Bacteria-Based Self-Healing Concrete

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Iranian Journal of science and technology - Transactions of Civil Engineering 2025年 1-13页

作者： Zamba, Duresa Dubale Mohammed, Tesfaye Alemu Getu, Yiglet Mebrat Tufa, Dereje Hailu Civil Engineering Department Addis Ababa Science and Technology University Addis Ababa Ethiopia Construction Quality and Technology Center of Excellence Addis Ababa Science and Technology University Addis Ababa Ethiopia Medical Biochemistry Ethiopian Biodiversity Institute Addis Ababa Ethiopia Molecular Biology Ethiopian Biodiversity Institute Addis Ababa Ethiopia

Concrete is susceptible to cracking under tension, which can lead to structural deterioration due to the penetration of acidic solutions and chemicals. Self-healing concrete presents an innovative solution by autonomously repairing surface cracks, reducing the need for costly and time-consuming maintenance. This study investigates the potential of Bacillus cereus in enhancing the self-healing and durability properties of C25-grade concrete. B. Cereus bacteria (10⁸ cells/ml) were utilized, and mechanical tests were conducted on both bacterial and control concrete specimens. Six pre-cracked samples from each group were monitored using a 3D optical microscope, and over 60 specimens were tested after 56 days of curing. Results showed that after 28 days, bacterial concrete exhibited increased compressive strength (16.67%), and flexural strength (8.59%) compared to control concrete. After 56 days, acid and salt resistance improved by 5.51% and 7.28%, respectively. Bacterial concrete also demonstrated 28.99% lower water absorption. The addition of bacteria resulted in a regain of compressive strength (17.88%, 5.29%, and 3.63% at 50%, 80%, and 100% loading, respectively) after 28 days. Analysis with a 3D microscope revealed increased white crystal precipitates, indicating effective crack filling facilitated by B. Cereus bacteria and calcite precipitation. These findings demonstrate that B. Cereus-based self-healing concrete enhances mechanical strength and durability, offering a sustainable and cost-effective alternative for resilient infrastructure. This novel technology holds significant potential for extending the lifespan of concrete structures and reducing maintenance demands. © The Author(s), under exclusive licence to Shiraz University 2025.

关键词： Bacillus cereus Bacteria-based Durability Mechanical strength Self-healing concrete

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Prediction of Fatigue Life of Materials Using Machine Learning Approach: A Review 11th

Prediction of Fatigue Life of Materials Using Machine Learni...

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11th EAI International Conference on Advancement of science and technology, ICAST 2023

作者： Tefera, Getaw Ayay Koricho, Ermias Gebrekidan Department of Mechanical Engineering Addis Ababa Science and Technology University Addis Ababa Ethiopia

ISBN: (纸本)9783031641503

Predicting the fatigue life of materials accurately and efficiently remains a challenge due to complex loading conditions, multidimensional stress factors, and the nonlinear properties of composite materials. However, advancements in data-driven modeling, specifically machine learning (ML) techniques, have shown promise in mitigating these limitations. Different ML models have been extensively employed to forecast the fatigue life of materials. This review provides a comprehensive analysis of data sources, ML model types, and evaluation techniques utilized in the field of ML-based fatigue life prediction. It is important to note that all ML models comprise two fundamental elements: datasets and algorithms employed during the training process. The ultimate objective of any ML model is to achieve accurate predictions, which necessitates the optimization of hyperparameters. Hyperparameter tuning is performed using various techniques, as there is no universally recognized rule for maximizing ML model accuracy. The present state of research in this field emphasizes expanding fatigue datasets, refining hyperparameter tuning methods, and identifying influential factors to enhance prediction accuracy while optimizing computational time and cost. This paper aims to provide a comprehensive understanding of the advancements made in ML-based fatigue life prediction, shedding light on potential avenues for future research. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Prediction models

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Insulation effect on post-earthquake fire punching shear behavior of slab–column connections

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Asian Journal of Civil Engineering 2023年第7期24卷 2505-2520页

作者： Mohammed, Tesfaye Alemu Shirtaga, Shewarega Construction Quality and Technology Center of Excellence Addis Ababa Science and Technology University Addis Ababa Ethiopia Department of Civil Engineering Addis Ababa Science and Technology University Addis Ababa Ethiopia

This research work numerically investigates effect of insulation on the punching shear behavior of interior GFRP-reinforced slab–column connections under post-earthquake fire. Two experimental results reported in the literature were used for validation analysis using ANSYS nonlinear finite-element software program. Further, parametric studies on influential variables such as fire exposure duration, application of vermiculite gypsum insulation system, and use of GFRP stirrups around the slab–column connections were performed to get insight into performance gains of using insulation on post-earthquake fire behavior of GFRP-reinforced slab–column connections. Finite-element analysis results showed use of vermiculite gypsum insulation system improved the punching shear capacity of GFRP-reinforced slab–columns by 20.99%. Compared to the control, increasing the thickness of vermiculite gypsum insulation to 11 mm, 15 mm and 20 mm reduced heat transfer in a slab by 72.96%, 76.51% and 79.62%, respectively, whereas the unbalanced drift moment ratio was enhanced in ranges 20.14% to 20.99%. Use of vermiculite gypsum insulation system to improve post-earthquake fire shear behavior of GFRP slab–beam connection is recommended. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Finite-element analysis Fire insulation Punching shear Slab–column connections

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Application of enhanced coagulation in drinking water treatment from the degraded catchment to reduce NOM: a major DBP precursor

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Water Supply 2025年第2期25卷 303-314页

作者： Hailu, Awraris Sishu, Feleke K. Faculty of Chemical and Food Engineering Bahir Dar Institute of Technology Bahir Dar6000 Ethiopia Department of Environmental Engineering Engineering College Addis Ababa Science and Technology University Addis Ababa Ethiopia

The occurrence of dissolved natural organic matter (NOM) in drinking water sources can potentially lead to the formation of disinfection byproducts (DBPs). In regions like the degraded soil of the Ethiopian highlands, which have low humic content, hydrophilic NOM tends to dominate. This study aimed to assess the effectiveness of enhanced coagulation in reducing precursors of DBPs in surface water used for drinking purposes. The Angereb reservoir, part of Gonder City’s water supply in the Ethiopian highlands, was chosen as the study area. Jar testing was conducted to evaluate the NOM removal efficiency of enhanced coagulation methods using ferric chloride and aluminum sulfate coagulants. Water samples were collected during both dry and wet seasons in 2023. Various parameters, such as total organic carbon (TOC), ultraviolet absorbance at a wavelength of 254 nm (UVA@254), pH, and other water quality indicators, were analyzed. Results revealed that the NOM present was primarily hydrophilic, as anticipated, with specific ultraviolet absorbance values below 2 L/mg-1 m-1. The existing treatment process, which involved prechlorination and coagulation with aluminum sulfate, removed less than 28% of TOC and 14% of UVA@254. However, using ferric chloride-enhanced coagulation achieved a removal efficiency of 50% for both TOC and UVA@254. © 2025 The Authors.

关键词： Runoff

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Assessing Cloud Service Quality: An Empirical Study in Ethiopia

Assessing Cloud Service Quality: An Empirical Study in Ethio...

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2024 International Conference on Information and Communication technology for Development for Africa, ICT4DA 2024

作者： Wondafrash, Natnael Gizaw, Solomon Hilcoe School of Computer Science and Technology Department of Computer Science Addis Ababa Ethiopia Addis Ababa University Department of Computer Science Addis Ababa Ethiopia

ISBN: (纸本)9798331527792

The study aimed to identify Cloud service evaluation metrics and evaluate the quality of cloud services in Governmental organizations, Non-Government Organizations, and Companies in Ethiopia. It found that the cloud services used in Ethiopian organizations have good quality based on several criteria. However, there were concerns about data security and portability. The study also showed that Infrastructure as a Service (IaaS) and Software as a Service (SaaS) are the most used service models, and the private cloud is the most used deployment model. Finally, the study proposed recommendations for future work and suggested that the cloud service evaluation metrics and deployment models in Ethiopia can provide valuable information for future studies and companies intending to use cloud services. © 2024 IEEE.

关键词： Cloud platforms

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Integrated municipal solid waste management using ArcGIS tools: A case of akaki-kality sub-city, addis ababa, ethiopia

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Environmental science and Pollution Research 2024年第50期31卷 59906-59930页

作者： Shibeshi, Abebaw Gebreabe, Solomon Tibebu Tiruneh, Amare Kassahun, Estifanos Sime, Takele Department of Environmental Engineering College of Engineering Sustainable Energy Center of Excellence Bioprocess and Biotechnology Center of Excellence Nanotechnology Center of Excellence Addis Ababa Science and Technology University Addis Ababa16417 Ethiopia Innovation Incubation Center and Intellectual Property Right Coordination Office University-Industry Linkage and Technology Transfer Directorate Nanotechnology Center of Excellence Addis Ababa Science and Technology University Addis Ababa16417 Ethiopia

This study aimed to optimize the solid waste collection and transportation system using ArcGIS Network Analyst and location-allocation tools. The generated solid waste was characterized by proximate analysis. The generation rate and composition were determined according to standard methods. The average solid waste generation rates for households, commercial sites, institutions, and recreational places were 0.48 kg/c/day, 15.03 kg/fac/day, 9.32 kg/fac/day, and 22.8 kg/fac/day, respectively. The estimated total generation rate of the sub-city is 207,004.03 kg/day and 712.13 m3/day as discarded base. Composition analysis revealed that food waste is the major component of municipal solid waste, with estimated weight and volume of 134,696.08 kg and 299.46 m3, respectively. Proximate analysis indicated that food and textile wastes have relatively high moisture content and fixed carbon. Candidate pre-collection bin allocations were optimized based on factors such as road network, distribution of solid waste generators, and existing temporary dumping sites, resulting in 1052 potential bin locations. Transfer station allocation was optimized by considering land use-land cover, slope, and geology. Twelve transfer routes and four transport routes were established to efficiently serve the bins and final waste destinations. In conclusion, the study demonstrates that ArcGIS Network Analyst and location-allocation tools can effectively optimize the municipal solid waste collection and transportation system, providing a robust framework for improving waste management efficiency. However, further research is recommended to validate these findings through field application. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Municipal solid waste

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Seismic performance evaluation of steel and GFRP reinforced concrete shear walls at high temperature

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Journal of Engineering and Applied science 2023年第1期70卷 4页

作者： Belay, Asfaw Wondimu, Temesgen Department of Civil Engineering College of Architecture and Civil Engineering Addis Ababa Science and Technology University Addis Ababa16417 Ethiopia

Fire-induced structural damage to the seismic performance of reinforced concrete shear walls is critical in the event of a fire-earthquake scenario. However, only few researchers have studied the seismic performance of reinforced concrete shear walls at high temperatures. This study focuses on the seismic performance of fiber reinforced concrete shear walls at high temperatures by using finite element (FE) software, ABAQUS. The experimental test available in a literature on seismic behavior of shear walls exposed to fire and thermal properties of glass fiber reinforced polymer (GFRP) bars were used to validate the FE model and showed good agreement and thus used in the simulation. The FE results showed that exposure of RC shear wall to fire reduced the strength of the wall. The strength of walls at the maximum applied drift of 3.2% with concrete cover thicknesses of 20 mm, 25 mm, and 30 mm was dropped by about 70%, 76%, and 85% of the reference shear wall, respectively. Similarly, the strength of RC walls was reduced by about 80%, 75%, and 68% of the reference shear wall for the duration of fire exposure of 30 min, 60 min, and 120 min, respectively. Additionally, the strength of walls due to one side, two sides, or all sides’ exposure to fire was decreased by about 68%, 56%, and 50% of the reference shear wall, respectively. It can generally be concluded that the fire exposure sides has largely affected the strength of the shear wall compared to the other parameters and GFRP bars were more sensitive to temperature than steel bars. © 2023, The Author(s).

关键词： Shear walls

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Stirring the hydrogen and butanol production from Enset fiber via simultaneous saccharification and fermentation(SSF)process

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Bioresources and Bioprocessing 2024年第1期11卷 1269-1287页

作者： Nebyat Seid Lea Wießner Habibu Aliyu Anke Neumann Electrobiotechnology Institute of Process Engineering in Life Science 2Karlsruhe Institute of Technology(KIT)76131 KarlsruheGermany School of Chemical and Bio Engineering Addis Ababa Institute of TechnologyAddis Ababa UniversityP.O.B:1176Addis AbabaEthiopia Institute for Biological Interfaces 5 Karlsruhe Institute of Technology(KIT)76344 KarlsruheGermany

Enset fiber is a promising feedstock for biofuel production with the potential to reduce carbon emissions and improve the sustainability of the energy *** study aimed to maximize hydrogen and butanol production from Enset fiber through simultaneous saccharification and fermentation(SSF)process in bottles as well as in *** SSF process in bottles resulted in a higher butanol concentration of 11.36 g/L with a yield of 0.23 g/g and a productivity of 0.16 g/(L h)at the optimal process parameters of 5%(w/v)substrate loading,16 FPU/g cellulase loading,and 100 rpm agitation speed from pretreated Enset ***,a comparable result to the bottle experiment was observed in the bioreactor with pH-uncontrolled SSF process,although with a decreased in butanol productivity to 0.095 g/(L h).However,using the pre-hydrolysis simultaneous saccharification and fermentation(PSSF)process in the bioreactor with a 7%(w/v)substrate loading led to the highest butanol concentration of 12.84 g/L with a productivity of 0.104 g/(L h).Furthermore,optimizing the SSF process parameters to favor hydrogen resulted in an increased hydrogen yield of 198.27 mL/g-Enset fiber at atmospheric pressure,an initial pH of 8.0,and 37°*** general,stirring the SSF process to shift the product ratio to either hydrogen or butanol was possible by adjusting temperature and *** 37°C and atmospheric pressure,the process resulted in an e-mol yield of 12%for hydrogen and 38%for ***,at 30°C and 0.55 bar overpressure,the process achieved a yield of 6%e-mol of hydrogen and 48%e-mol of *** is the first study to produce hydrogen and butanol from Enset fiber using the SSF process and contributes to the development of a circular bioeconomy.

关键词： Hydrogen Butanol Enset fiber C.saccharoperbutylacetonicum SSF PSSF

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