International Journal of Engineering Research in Africa最新文献

{"title":"Network Structure and Water Absorption of Soil Moisture Gel by Coarse-Grained Molecular Dynamics Simulations","authors":"Haifei Jiang","doi":"10.4028/p-r8o1xc","DOIUrl":"https://doi.org/10.4028/p-r8o1xc","url":null,"abstract":"With the wide application of hydrogel materials in agriculture, forestry, flexible electronics, electronic information engineering, environmental detection, flexible electronics, information science, technology and so on, the development of various new functional hydrogel materials has gradually become one of the research hotspots. At present, the research on hydrogel materials is mainly focused on the preparation of various functional hydrogels by experimental methods, there is no fundamental understanding of the relationship between the “stimulus-response” and its inner microstructures. In this paper, the author uses the molecular dynamics simulation method to study the evolution of the hydrogel’s microscopic network structure, the relationship between microstructure and water absorption of hydrogels in the processes of water swelling and “stimulus-response”. The next generation of new super absorbent, high toughness, high strength and other functional hydrogels could be synthesized by the guide of this study, and these new hydrogels have a promising future to apply in new fields of technology such as flexible electronics, and biological medicine.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"63 1","pages":"1 - 12"},"PeriodicalIF":0.7,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46718637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wind Energy Resource Potential Evaluation based on Statistical Distribution Models at Four Selected Locations in Amhara Region, Ethiopia","authors":"Yosef Berhan Jember, Gashaye Lewtie Hailu, Abrham Tadesse Kassie, Destaw Addisu Bimrew","doi":"10.4028/p-bt68b3","DOIUrl":"https://doi.org/10.4028/p-bt68b3","url":null,"abstract":"In Ethiopia, and particularly in the Amhara region, the government as well as the concerned organization would not give special attention to establishing wind energy plants. Lack of scientific research inputs about potential assessment can be one of the reasons behind it. In this paper, a wind energy potential assessment for Debel, Malawa, Enwari, and Ayba Eyesus sites in the Amhara region has been investigated. Five statistical distribution methods namely Weibull 3P, Weibull 2P, Rayleigh 2P, Normal, and Lognormal are used to fit the data to the probability density function and cumulative distribution function. The proposed parameter estimation method, to precisely predict the values of the shape parameter, scale parameter, and location parameter, was the Maximum Likelihood Estimation Method (MLE). To analyze the goodness of fit of the models, Kolmogorov, Andersen Darling, and Chi-Square have been used. The test indicated that Weibull 3P is the best fitting method, except for Ayba Eyesus, which is suited to Weibull 2P. For Debel, Malawa, Enwari, and Ayba Eyesus, the maximum annual average wind power density was found to be 74.291 W/m2, 19.183 W/m2, 68.972 W/m2, and 49.221 W/m2 correspondingly. The evaluations show that VENSYS 87 turbine model has better performance in all three sites except Enwari, where Inox Wind DF 100 is favored. With their best performance turbine, the capacity factor of the sites is determined as 14%, 7%, 12%, and 14% for Debel, Malawa, Enwari, and Ayba Eyesus respectively. Furthermore, Economical analysis by initial cost, lifetime, operation, and maintenance cost, has been carried out to estimate the cost of energy. With VENSYS 87 turbine model, the three sites' present value costs are $5,479,586, while it costs $7,306,115 in Enwari with Inox Wind DF 100 turbine. The cost of electricity per kWh is estimated to be $0.00231, $0.00455, $0.00391, and $0.00312 for Debel, Malawa, Enwari, and Ayba Eyesus respectively, and it is significantly lower than the cost from Ethiopian electric utility (EEU), which is around 0.009$/kwh. Access to electricity in Ethiopia was reported at 45% in 2019. This indicates there is a shortage of energy in the country. This kind of study can help authorities and policymakers in taking into account wind power to mitigate energy poverty in the country.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"63 1","pages":"137 - 158"},"PeriodicalIF":0.7,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70641582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Low-Cost Control Architecture for Buck Converter Fed VSI Based BLDC Motor Drive","authors":"M. Kurre, S. Deshmukh, Rajdeep Tandekar, Pratikanta Mishra, A. Banerjee","doi":"10.4028/p-34izda","DOIUrl":"https://doi.org/10.4028/p-34izda","url":null,"abstract":"In this paper, a novel low-cost digital controller to drive a buck converter fed voltage source inverter (VSI) based brushless DC (BLDC) machine has been proposed. This controller is designed to be implemented solely in digital platforms and has multiple numbers of predefined discrete duty ratios. In conjunction with buck converter fed VSI, the controller is beneficial to enhance the speed and resultant torque profile of BLDC motor drive as compared to conventional bang-bang or on-off controller. The controller also incorporates a current limiter to avoid the over-current loading of the motor. The sampling time and the design of the current limiter are mathematically derived in the paper. The working efficiency of the developed controller for the BLDC motor drive has been examined for various vital and steady-state conditions. The speed ripples, settling time, tolerance to the commanded speed, and load variations are validated and presented in this paper. The proposed controller has been performed and implemented in the field-programmable gate array platform and compared to generic pre-existing controllers to validate the cost-effectiveness of the controller.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"161 - 171"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46956728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Static and Dynamic Analysis of Keddara Dam","authors":"Samya Chebout, R. Bahar","doi":"10.4028/p-81xn1p","DOIUrl":"https://doi.org/10.4028/p-81xn1p","url":null,"abstract":"The numerical analysis using finite difference method to study static and dynamic performance of embankment dams is a complex process, in which the materials behavior, soil-dam foundation interaction, hydraulic conditions and saturation effects, should be taken into account. In this study, static and dynamic analysis of Keddara earth dam, located in Boumerdes region (Algeria), is conducted by a numerical analysis using finite difference method (FLAC 3D), with the objective to define its behavior in terms of settlement, strain and pore pressure variation, during its construction and operation. Two stages are considered; the dam construction stage and water filling stage. In this way, two mathematical models are considered for the static analysis; the elastic model and Mohr-Coulomb model. To conduct a coupled dynamic analysis a real earthquake record is used and the interaction between the fluid and solid phases is taken into account.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"71 - 84"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45960476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined Thermal Performance Enhancement of Parabolic Trough Collectors Using Alumina Nanoparticles and Internal Fins","authors":"Mohamed H. Yehia, Muhammed A. Hassan, Nabeel Abed, A. Khalil, N. Bailek","doi":"10.4028/p-63cdb1","DOIUrl":"https://doi.org/10.4028/p-63cdb1","url":null,"abstract":"Parabolic trough collectors are the currently dominant technology for concentrated solar power systems, employed to produce thermal energy at low to medium temperatures (up to 400°C). Extensive research has been carried out to enhance the thermal efficiency and reduce the power production costs of these concentrators. However, there is a lack of studies on combined passive performance enhancement using alternative fluids and absorber designs. In this study, the thermal performance of a full-sized parabolic trough collector is analyzed with the presence of internal longitudinal fins in combination with the use of oil-based nanofluid (Al2O3-Syltherm 800) of different volume fractions. The governing equations are numerically solved using ANSYS FLUENT 17.1 software and the Monte-Carlo ray-tracing (MCRT) model was used to apply the non-uniform heat flux profile over the external surface of the solar receiver. The results show that both techniques enhance thermal energy utilization and reduce radiative and convective thermal losses, resulting in higher thermal efficiency, but also larger pressure losses. The thermal performance is enhanced by 0.1-1.16 % with nanofluid, up to 6.8 % with internal fins, and by up to 7.25 % when both techniques are adopted. These enhancements are attributed to the reduced mean circumferential temperature of the absorber tube.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"107 - 132"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48493740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selection of a Pavement Structure from Technically Established Alternatives Based on Construction Cost, Energy Consumption, and Carbon Footprint","authors":"Wissem Taktak, A. Loulizi","doi":"10.4028/p-xx05a5","DOIUrl":"https://doi.org/10.4028/p-xx05a5","url":null,"abstract":"This paper presents a procedure to select a pavement structure from technically established alternatives. The general proposed process relies on calculating the present worth of total cost resulting from construction, maintenance/rehabilitation, energy consumption and carbon footprint during those activities as well as recycling of the materials at their end life. However, depending on data availability, the general process could be reduced to just the construction phase as is the case in most developing countries where required pavement performance data is scarce. The reduced procedure was validated on four types of pavements for six traffic levels and three subgrade types. Under the conditions considered in this study, it was found that concrete pavements have high construction, embodied energy, and carbon footprint costs (the environmental impact represents about 66% of the total cost) as compared to other pavement types. Full-depth asphalt pavements were found to be the best ecological type, their construction cost is a little higher than the environmental one with a distribution of about 53% and 47%, respectively. Inverted pavements seem to be a good alternative to weak subgrades although the costs associated with environmental effects contribute to about 52% of the total cost.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"85 - 106"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47423300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damping Subsynchronous Oscillations Using a High Voltage Direct Current-Based Multi-Modal Damping Controller","authors":"C. B. Tambwe, R. P. Carpanen","doi":"10.4028/p-530sb3","DOIUrl":"https://doi.org/10.4028/p-530sb3","url":null,"abstract":"Conventional series capacitors in transmission lines are of paramount importance for enhancing power transfer capability. However, the major drawback of series capacitors is the induced subsynchronous resonance phenomenon in power systems. This phenomenon affects nearby turbogenerator shafts and severely limits their reliability. Also, the controls of High Voltage Direct Current links are considered as a potential source of subsynchronous oscillations. This paper investigates the performance of a multimodal damping controller to stabilize unstable torsional modes in combination with a Power System Stabilizer for inertial mode damping. This research uses time-domain simulation-based multimodal damping controller design methods, namely the test signal and phase correction methods. These two methods involve injecting a test signal at a frequency of interest into the rectifier current control loop and measuring its phase difference with the electromagnetic torque, thus providing corresponding compensators to minimize the resulting angle. This work uses Power System Computer-Aided Design for time-domain simulation and Fast Fourier Transforms Analysis to conduct the phase correction method and verify controller performance.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"133 - 160"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41405592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pilot Implementation of Innovative Proposal for Service Level Improvement in a Spare Parts Trading Company","authors":"Emma Ramos-Valle, André Paulino, Pedro Chavez, J. Alvarez, S. Nallusamy","doi":"10.4028/p-70sd0q","DOIUrl":"https://doi.org/10.4028/p-70sd0q","url":null,"abstract":"In the context in which spare parts trading companies are becoming increasingly competitive, the level of service is essential to be able to compete in the market. This indicator is affected by on-time deliveries, which are a key factor in meeting customer demand, as this determines customer satisfaction and thus has an effect on the company's profitability. For a company to deliver its products on time, the warehouse processes must work efficiently, making the picking process one of the most critical of them. It must also run a proper inventory procurement process in order to have stock on hand to fulfill customer orders. This case study focuses on increasing the level of service in a company that sells spare parts for mining, which was found to have a low service level of 66.1%, in contrast to the recommended level for the sector, which is 85.9%. Therefore, the implementation of the 5S methodology, Systematic layout planning, demand forecasting, and cycle counting are proposed as tools to solve the root causes of the problem. The main results indicated a reduction in picking times of 36.70%, an increase in demand forecast accuracy of 13.45%, and an increase in Inventory Record Accuracy (IRA) of 5.42%.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"173 - 187"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47624216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Waste Glass Powder on Properties of Self-Compacting Repair Mortars","authors":"A. Benyahia, M. Salhi, Toufik Boubekeur","doi":"10.4028/p-1eiar8","DOIUrl":"https://doi.org/10.4028/p-1eiar8","url":null,"abstract":"This paper studies the effects of fine waste glass powder content (WGP) on fresh and hardened properties of self-compacting repair mortar mixes (SCRMs). For this purpose, mortar mixes were prepared to replace cement with waste glass powder ranging from 0 to 30% at 10% interval and tested. Fresh properties were assessed using mini-slump flow and mini V-funnel. Hardened properties assessed for all mixes were water absorption (at 28-days of age), compressive and flexural strengths (at 7, 28 and 56-days of age). In addition, the adhesion between the repair mortar mixes and substrate was conducted using a 3-point flexural test on a composite prism (half mortar/half substrate) at 28 and 56-days of age. The results showed that glass powder had a negative effect on the workability of mortars. However, in the hardened state, it had a good influence on the strength development after 28 days, durability and adhesion of mortars with the substrate for a waste glass powder content not exceeding 20%.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"43 - 56"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48145579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of the Hardness of Pulverized Glass Waste-Reinforced Aluminium Alloy 6061-T6 Friction Stir Welded Joint","authors":"T. Abioye, Ebenezer Olanipekun, A. S. Anasyida","doi":"10.4028/p-j02z6p","DOIUrl":"https://doi.org/10.4028/p-j02z6p","url":null,"abstract":"The purpose of this study is to investigate the friction stir weld quality of pulverized glass waste (PGW)-reinforced AA6061-T6 and develop a model predicting the hardness of the joint. Friction stir welding of PGW-reinforced AA6061-T6 was done within a process window. The process was optimized for the maximum joint hardness. Thereafter, the result of the hardness was used to develop a model using a novel statistical analytical technique. The addition of PGW enhanced the AA6061-T6 friction stir welded joint hardness. The maximum hardness (112 HV) of the PGW-reinforced joint, which was obtained at optimal setting of 900 rpm rotational speed, 40 mm/min traverse speed and 1o tilt angle, is by a factor of 1.72 greater than the unreinforced joint and close to the hardness of the as-received AA6061-T6 (120 HV). The developed model can predict the hardness of the PGW-reinforced AA6061-T6 joint up to an accuracy of 89%. The model shows that the rotational speed, tilt angle and their interaction contributed significantly to the hardness of the PGW-reinforced AA6061-T6 friction stir welded joint. This model is suitable for determining the hardness property of particle-reinforced AA6061-T6 friction stir welded joint at varying processing parameters.","PeriodicalId":45925,"journal":{"name":"International Journal of Engineering Research in Africa","volume":"62 1","pages":"31 - 42"},"PeriodicalIF":0.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48225788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}