I. A. Fetuga, O. O. Olakoyejo, O. Oluwatusin, A. O. Adelaja, J. K. Gbegudu, K. S. Aderemi, E. A. Adeyemi
This work presents a three-dimensional computational study of nanoparticles (metallic and non-metallic) suspended in blood flowing through a diseased artery with both stenosis and aneurysm. From the perspective of pharmacodynamics and heat transfer, the influence of nanoparticles on hemodynamic indicators was investigated in a diseased artery. The blood was flowing fluid, steady-state, incompressible, homogeneous, and Newtonian, while the artery was a rigid wall. The three-dimensional continuity, Navier-Stokes, and energy equations were solved numerically by using a RAN-based standard k-ω model, which was performed on the ANSYS commercial software package. The influence of different selected nanoparticles (Al2O3, CuO, SiO2, and ZnO), nanoparticle concentration (1.0%-4.0%), and nanoparticle diameters (25 nm - 100 nm) on hemodynamic parameters such as velocity, temperature, turbulence intensity, more particularly skin friction coefficient and Nusselt number of the blood flow on the diseased artery, was also investigated. The streamlines, contours, and plots were adopted to better visualize the blood flow behavior in an artery with stenosis and aneurysm. The numerical results revealed that at a 4.0% nanoparticle concentration, CuO nanoparticles greatly reduced the blood velocity by 1.96% compared to other nanoparticles. About 0.66%-2.05% reduction in the blood velocity could be achieved by increasing the nanoparticle concentration from 1.0% to 4.0%. The SiO2 blood nanofluid showed the best result in augmentation of the Nusselt number by 53.0%. However, the nanoparticle diameter and concentration showed an insignificant effect on the skin friction factor.
{"title":"Computational model of nano-pharmacological particles for the clinical management of stenotic and aneurysmatic coronary artery in the human body","authors":"I. A. Fetuga, O. O. Olakoyejo, O. Oluwatusin, A. O. Adelaja, J. K. Gbegudu, K. S. Aderemi, E. A. Adeyemi","doi":"10.4314/njtd.v20i1.1293","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1293","url":null,"abstract":"This work presents a three-dimensional computational study of nanoparticles (metallic and non-metallic) suspended in blood flowing through a diseased artery with both stenosis and aneurysm. From the perspective of pharmacodynamics and heat transfer, the influence of nanoparticles on hemodynamic indicators was investigated in a diseased artery. The blood was flowing fluid, steady-state, incompressible, homogeneous, and Newtonian, while the artery was a rigid wall. The three-dimensional continuity, Navier-Stokes, and energy equations were solved numerically by using a RAN-based standard k-ω model, which was performed on the ANSYS commercial software package. The influence of different selected nanoparticles (Al2O3, CuO, SiO2, and ZnO), nanoparticle concentration (1.0%-4.0%), and nanoparticle diameters (25 nm - 100 nm) on hemodynamic parameters such as velocity, temperature, turbulence intensity, more particularly skin friction coefficient and Nusselt number of the blood flow on the diseased artery, was also investigated. The streamlines, contours, and plots were adopted to better visualize the blood flow behavior in an artery with stenosis and aneurysm. The numerical results revealed that at a 4.0% nanoparticle concentration, CuO nanoparticles greatly reduced the blood velocity by 1.96% compared to other nanoparticles. About 0.66%-2.05% reduction in the blood velocity could be achieved by increasing the nanoparticle concentration from 1.0% to 4.0%. The SiO2 blood nanofluid showed the best result in augmentation of the Nusselt number by 53.0%. However, the nanoparticle diameter and concentration showed an insignificant effect on the skin friction factor.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46703517","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}
T. A. Olaleye, L. Olatomiwa, O. M. Longe, K. E. Jack
This paper presents a Fuzzy Logic Controller-based energy management system (EMS) to control hybrid energy sources. The design is a single-phase and grid-tied system sized to handle the system's diverse load demands. The design system consists of photovoltaic modules, a grid source and a single-phase standby generator. The system uses energy produced by the PV modules (using Perturbation and Observation MPPT to maximize energy generated from the modules) and power stored in the Energy Storage Unit (ESU) to fulfil the various load needs while prioritizing the selling of excess energy to the grid. The fuzzy controller controls and manages the highlighted operational activities and prevents the ESU from overcharging and undercharging. Simulink is adopted to implement the proposed system within the simulation period; as the irradiation increased from 0W/m2 to 100W/m2, the grid's power supply dropped from 6000W to 4000W because of the amount of PV power generation between 0.6s and 0.8s. The photovoltaic module contributed to the system's overall power consumption while keeping the DC bus voltage between 396V and 406V. The EMS using the fuzzy logic controller provides high levels of energy security, system effectiveness and O &M cost optimization. It has also offered a consistent and uninterrupted power supply.
{"title":"An energy management scheme for hybrid energy system using Fuzzy Logic Controller","authors":"T. A. Olaleye, L. Olatomiwa, O. M. Longe, K. E. Jack","doi":"10.4314/njtd.v20i1.1292","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1292","url":null,"abstract":"This paper presents a Fuzzy Logic Controller-based energy management system (EMS) to control hybrid energy sources. The design is a single-phase and grid-tied system sized to handle the system's diverse load demands. The design system consists of photovoltaic modules, a grid source and a single-phase standby generator. The system uses energy produced by the PV modules (using Perturbation and Observation MPPT to maximize energy generated from the modules) and power stored in the Energy Storage Unit (ESU) to fulfil the various load needs while prioritizing the selling of excess energy to the grid. The fuzzy controller controls and manages the highlighted operational activities and prevents the ESU from overcharging and undercharging. Simulink is adopted to implement the proposed system within the simulation period; as the irradiation increased from 0W/m2 to 100W/m2, the grid's power supply dropped from 6000W to 4000W because of the amount of PV power generation between 0.6s and 0.8s. The photovoltaic module contributed to the system's overall power consumption while keeping the DC bus voltage between 396V and 406V. The EMS using the fuzzy logic controller provides high levels of energy security, system effectiveness and O &M cost optimization. It has also offered a consistent and uninterrupted power supply.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46839542","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}
The incorporation of pozzolanic materials in concrete construction is progressively increasing. This is due to technological advancement and climate change problems associated with carbon emissions resulting from the large-scale manufacturing of cement and its usage for concrete production. In this study, metakaolin obtained was used to partially substitute cement in metakaolin-concrete. Calcination temperatures of kaolin were varied from 500°C to 800°C at an interval of 100°C for 60 minutes. The metakaolin obtained was used to partially replace cement at 0, 5, 10, 15, 20 and 25 % by weight using a mix ratio of 1:2:4 and 0.4 water-cement ratio. Compressive strength test was carried out at curing ages of 7, 28 and 90 days, while the flexural strength test was performed at curing ages of 28 and 90 days. For both compressive and flexural strengths, 15 % by weight replacement with metakaolin gave the best strength values at all temperatures. An Increase in temperature led to a significant increase in the strength of metakaolin-concrete. ANOVA showed all factors significantly affected the flexural strength (P < 0.1), whilst the calcination temperature was significant (P < 0.1) to the compressive strength. This study showed that metakaolin is a supplementary cementitious material (SCM) and is a potential alternative to cement and can be used in the construction industry. Also, the calcination temperature of kaolin has a significant effect on the properties of the resulting metakaolin-concrete produced from it.
{"title":"Effect of calcination temperatures of kaolin on compressive and flexural strengths of metakaolin-concrete","authors":"Y. Abiodun, J. I. Orisaleye, S. Adeosun","doi":"10.4314/njtd.v20i1.1390","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1390","url":null,"abstract":"The incorporation of pozzolanic materials in concrete construction is progressively increasing. This is due to technological advancement and climate change problems associated with carbon emissions resulting from the large-scale manufacturing of cement and its usage for concrete production. In this study, metakaolin obtained was used to partially substitute cement in metakaolin-concrete. Calcination temperatures of kaolin were varied from 500°C to 800°C at an interval of 100°C for 60 minutes. The metakaolin obtained was used to partially replace cement at 0, 5, 10, 15, 20 and 25 % by weight using a mix ratio of 1:2:4 and 0.4 water-cement ratio. Compressive strength test was carried out at curing ages of 7, 28 and 90 days, while the flexural strength test was performed at curing ages of 28 and 90 days. For both compressive and flexural strengths, 15 % by weight replacement with metakaolin gave the best strength values at all temperatures. An Increase in temperature led to a significant increase in the strength of metakaolin-concrete. ANOVA showed all factors significantly affected the flexural strength (P < 0.1), whilst the calcination temperature was significant (P < 0.1) to the compressive strength. This study showed that metakaolin is a supplementary cementitious material (SCM) and is a potential alternative to cement and can be used in the construction industry. Also, the calcination temperature of kaolin has a significant effect on the properties of the resulting metakaolin-concrete produced from it.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45745271","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}
Prevention of authorized users from interference determine the accurate detection of Spectrum Hole (SH) is of great importance in a Spectrum Shearing Network (SSN). However, multipath fading and shadowing affect the accurate detection of SH resulting in interference. Cluster-Based Cooperative Spectrum Hole Detection (CBCSHD) used to address this problem depends on detector and number of clusters. Hence, comparative analysis of blind detectors in CBCSHD is carried out to evaluate its performance with various blind detectors and number of clusters. The CBCSHD is carried out using six Cognitive Users (CUs) that jointly carry out detection of SH and each of the CUs performs local sensing using Eigenvalue Detector (EVD), Energy Detector (ED) and Cyclostationary Detector (CD). The CUs form clusters to reduce reporting overhead between CUs. The local sensing results from individual user are combined at the Cluster Head (CH) using majority fusion rule. The performance of each of the detectors in CBCSHD is evaluated using Probability of Detection (PD) and Sensing Time (ST). PD values of 0.7661, 0.7160 and 0.6229 are obtained at SNR of 4 dB for ED, CD and EVD, respectively, while ST values of 3.0707, 3.7163 and 4.0907 s are obtained for ED, CD and EVD, respectively. The results obtained show that ED has the highest detection rate, followed by CD, while EVD shows the worst detection rate.
{"title":"Comparative analysis of blind detectors in a cluster-based cooperative Spectrum Hole detection","authors":"S. I. Ojo, Z. K. Adeyemo, R. O. Omowaiye","doi":"10.4314/njtd.v20i1.1300","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1300","url":null,"abstract":"Prevention of authorized users from interference determine the accurate detection of Spectrum Hole (SH) is of great importance in a Spectrum Shearing Network (SSN). However, multipath fading and shadowing affect the accurate detection of SH resulting in interference. Cluster-Based Cooperative Spectrum Hole Detection (CBCSHD) used to address this problem depends on detector and number of clusters. Hence, comparative analysis of blind detectors in CBCSHD is carried out to evaluate its performance with various blind detectors and number of clusters. The CBCSHD is carried out using six Cognitive Users (CUs) that jointly carry out detection of SH and each of the CUs performs local sensing using Eigenvalue Detector (EVD), Energy Detector (ED) and Cyclostationary Detector (CD). The CUs form clusters to reduce reporting overhead between CUs. The local sensing results from individual user are combined at the Cluster Head (CH) using majority fusion rule. The performance of each of the detectors in CBCSHD is evaluated using Probability of Detection (PD) and Sensing Time (ST). PD values of 0.7661, 0.7160 and 0.6229 are obtained at SNR of 4 dB for ED, CD and EVD, respectively, while ST values of 3.0707, 3.7163 and 4.0907 s are obtained for ED, CD and EVD, respectively. The results obtained show that ED has the highest detection rate, followed by CD, while EVD shows the worst detection rate.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42431555","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}
In this study, the main task is to identify the best cutting parameters to improve the machining performance during MQL-turning with various cutting fluids like coconut oil, ground nut oil, sunflower oil, soyabean oil, and blassocut oil. Cutting temperature and surface roughness were used as performance metrics, with the goal of minimizing these responses. To construct an experimental plan for turning AISI4130 with uncoated brazed carbide, full factorial design for three levels and three factors (33) design of experiments was used. The optimalcutting parameter was identified using the response surface approach. Aiming to discover the optimum possible cutting settings, the desirability function method was utilized. It was discovered that the best cutting speed, depth of cut, and feed rate for minimizing the temperature and surface roughness are 72.38 m/min, 0.5 mm, and 0.35 mm/rev respectively. According to the ANOVA findings, the feed and depth of cut have a substantial impact on the tool temperature for MQL-soyabean oil.
{"title":"Optimization of Cutting Parameters using the RSMDesirability Approach in the MQL-Assisted Turning of AISI 4130","authors":"Dr.Nilesh C. Ghuge, D. Palande, P. B. Belkhode","doi":"10.4314/njtd.v19i4.4","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.4","url":null,"abstract":"In this study, the main task is to identify the best cutting parameters to improve the machining performance during MQL-turning with various cutting fluids like coconut oil, ground nut oil, sunflower oil, soyabean oil, and blassocut oil. Cutting temperature and surface roughness were used as performance metrics, with the goal of minimizing these responses. To construct an experimental plan for turning AISI4130 with uncoated brazed carbide, full factorial design for three levels and three factors (33) design of experiments was used. The optimalcutting parameter was identified using the response surface approach. Aiming to discover the optimum possible cutting settings, the desirability function method was utilized. It was discovered that the best cutting speed, depth of cut, and feed rate for minimizing the temperature and surface roughness are 72.38 m/min, 0.5 mm, and 0.35 mm/rev respectively. According to the ANOVA findings, the feed and depth of cut have a substantial impact on the tool temperature for MQL-soyabean oil.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42391770","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}
S. A. Kamilu, L. Olatomiwa, O. M. Longe, S. Ikuforiji
The intermittent nature of the wind resources and reactive power consumptions are major issues associated with squirrel cage induction generator wind power system when operated in an island microgrid mode. The resultant effect of these two issues are continuous fluctuations of load voltage which has adverse effects on electrical devices. This paper proposes a voltage regulation technique based on proportional controller and phase deposition sine pulse width modulation (PDSPWM) for the control of 5-level neutral point clamped multilevel inverter. The instantaneous voltage tracking strategy based on root mean square value of microgrid voltage was adopted to regulate and maintain the output load voltage at 400 𝑉𝑟𝑚𝑠 despite rotor fluctuations with wind speeds. The simulation was carried out in a MATLAB/SIMULINK environment and the performance of the control scheme was found to be excellent.
{"title":"Load Voltage Control of a Wind Turbine-driven Three-phase Squirrel-Cage Induction Generator in an Islanded Microgrid","authors":"S. A. Kamilu, L. Olatomiwa, O. M. Longe, S. Ikuforiji","doi":"10.4314/njtd.v19i4.13","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.13","url":null,"abstract":"The intermittent nature of the wind resources and reactive power consumptions are major issues associated with squirrel cage induction generator wind power system when operated in an island microgrid mode. The resultant effect of these two issues are continuous fluctuations of load voltage which has adverse effects on electrical devices. This paper proposes a voltage regulation technique based on proportional controller and phase deposition sine pulse width modulation (PDSPWM) for the control of 5-level neutral point clamped multilevel inverter. The instantaneous voltage tracking strategy based on root mean square value of microgrid voltage was adopted to regulate and maintain the output load voltage at 400 𝑉𝑟𝑚𝑠 despite rotor fluctuations with wind speeds. The simulation was carried out in a MATLAB/SIMULINK environment and the performance of the control scheme was found to be excellent.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43857969","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}
Flux limiters are widely used in numerical simulations to prevent spurious oscillation in the flow with strong property gradients. However, applying flux limiter on flow without strong property gradient such as advection-diffusion flow can cause errors. This article discusses the errors caused by several flux limiters in advection-diffusion flow solution. A method for applying one-dimensional limiters to two-dimensional unstructured mesh was also suggested. The error was measured by comparing the finite volume solution of a test case with a reference solution. The study shows that the calculation error of second-order finite volume with flux limiter was higher than that of second-order finite volume without limiter. However, the error of third-order finite volume with flux limiter is less than that of second-order without flux limiter. Among the flux limiters tested in this study, Venkatakrishnan’s flux limiter produces the highest error, followed by Van leer’s limiter, EULER and SMART limiter.
{"title":"Comparison of Errors Caused by Flux Limiters on the Numerical Solution of Advection-Diffusion Problem","authors":"Adek Tasri","doi":"10.4314/njtd.v19i4.3","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.3","url":null,"abstract":"Flux limiters are widely used in numerical simulations to prevent spurious oscillation in the flow with strong property gradients. However, applying flux limiter on flow without strong property gradient such as advection-diffusion flow can cause errors. This article discusses the errors caused by several flux limiters in advection-diffusion flow solution. A method for applying one-dimensional limiters to two-dimensional unstructured mesh was also suggested. The error was measured by comparing the finite volume solution of a test case with a reference solution. The study shows that the calculation error of second-order finite volume with flux limiter was higher than that of second-order finite volume without limiter. However, the error of third-order finite volume with flux limiter is less than that of second-order without flux limiter. Among the flux limiters tested in this study, Venkatakrishnan’s flux limiter produces the highest error, followed by Van leer’s limiter, EULER and SMART limiter.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41507003","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}
A. B. Nandiyanto, E. S. Soegoto, S. Maulana, Andika Fajar Setiawan, F. S. Almay, M. Hadinata, R. Ragadhita, S. Luckyardi
This study aimed to assess the economic and engineering feasibility of a large-scale biodiesel manufacturing operation from edible oil waste. The edible oil model used for economic analysis in this study is palm oil waste. Several economic parameters (i.e., gross profit margin (GPM), payback period (PBP), break-even point (BEP), cumulative net present value (CNPV), profitability index (PI)), and internal rate return (IRR) were examined to inform the potential production of biodiesel from edible oil waste in ideal condition. To confirm the feasibility of a manufacturing project, the project is estimated from ideal to worst-case conditions in production activities such as analysis of changing raw material, labor, tax, utility, and selling price costs. Based on an engineering perspective, the result indicated that biodiesel production from edible and non-edible oil is feasible. From an economic perspective, economic analysis shows that biodiesel production from edible oil waste is promising because the economic parameters as analyzed show positive results. Our findings are expected to provide an industrial-scale picture of economic evaluation and layout, particularly in the production of biodiesel, which is commonly used as a renewable energy source for fuel in trucks, trains, ships, and barges.
{"title":"Techno-economic Evaluation of Biodiesel Production from Edible Oil Waste via Supercritical Methyl Acetate Transesterification","authors":"A. B. Nandiyanto, E. S. Soegoto, S. Maulana, Andika Fajar Setiawan, F. S. Almay, M. Hadinata, R. Ragadhita, S. Luckyardi","doi":"10.4314/njtd.v19i4.6","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.6","url":null,"abstract":"This study aimed to assess the economic and engineering feasibility of a large-scale biodiesel manufacturing operation from edible oil waste. The edible oil model used for economic analysis in this study is palm oil waste. Several economic parameters (i.e., gross profit margin (GPM), payback period (PBP), break-even point (BEP), cumulative net present value (CNPV), profitability index (PI)), and internal rate return (IRR) were examined to inform the potential production of biodiesel from edible oil waste in ideal condition. To confirm the feasibility of a manufacturing project, the project is estimated from ideal to worst-case conditions in production activities such as analysis of changing raw material, labor, tax, utility, and selling price costs. Based on an engineering perspective, the result indicated that biodiesel production from edible and non-edible oil is feasible. From an economic perspective, economic analysis shows that biodiesel production from edible oil waste is promising because the economic parameters as analyzed show positive results. Our findings are expected to provide an industrial-scale picture of economic evaluation and layout, particularly in the production of biodiesel, which is commonly used as a renewable energy source for fuel in trucks, trains, ships, and barges.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46498843","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}
The goal of cooperative communication is to increase spatial diversity and wireless network coverage. However, in a classical relaying setup, where a single best relay is chosen to receive the source's data in the first time slot and retransmit in the second time slot regardless of channel circumstances, channel mismatch occurs. In this paper, we have developed an enhanced relay selection technique at the relay nodes that incorporates buffers to address the aforementioned problem. The outage probability and throughput computations are derived using closed-form formulas. The results obtained show that the enhanced relay selection technique gives lower values in outage probability and higher values in throughput when compared with the conventional technique, providing it a desirable strategy for use in technical communication.
{"title":"Buffer-aided Relay Selection Technique in a Cooperative Communication Network","authors":"S. B. Ajibowu, O. Adeleke, I. A. Ojerinde","doi":"10.4314/njtd.v19i4.8","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.8","url":null,"abstract":"The goal of cooperative communication is to increase spatial diversity and wireless network coverage. However, in a classical relaying setup, where a single best relay is chosen to receive the source's data in the first time slot and retransmit in the second time slot regardless of channel circumstances, channel mismatch occurs. In this paper, we have developed an enhanced relay selection technique at the relay nodes that incorporates buffers to address the aforementioned problem. The outage probability and throughput computations are derived using closed-form formulas. The results obtained show that the enhanced relay selection technique gives lower values in outage probability and higher values in throughput when compared with the conventional technique, providing it a desirable strategy for use in technical communication.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46320589","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}
Nowadays, along with the developments in the industry, many machines and structures are exposed to very high-temperature environments, which has caused various types of thermal load in them. These conditions have led to focused studies on thermal stresses in structures. Heat exchangers are among the structures in which the temperature difference causes thermal stress. In this paper, “finite volume” and “finite element” methods are used to solve flow equations and thermal stress equations in solids, respectively. In addition, the effect of changes in the shape of the annular finned pipe on the thermal stresses in the heat exchanger is investigated. The study results on changing the pipe shape from circular to elliptical show that by changing the pipe shape, the thermal stress in the fin can be significantly reduced; for instance, in the cases reviewed in this paper, the thermal stress has decreased by 9%. Furthermore, the results of thermal stress show that the Maximum Effective Stress point, both before and after changing the shape, is still located at the fin’s base. So, according to the results of this study, examining the effect of pipe shape changing on thermal stress is an imperative measure when designing heat exchangers.
{"title":"Effects of Annular-finned Tube Deformation on Thermal Stresses in a Heat Exchanger","authors":"M. Kashani, A. Hatami, M. Hosseini","doi":"10.4314/njtd.v19i4.2","DOIUrl":"https://doi.org/10.4314/njtd.v19i4.2","url":null,"abstract":"Nowadays, along with the developments in the industry, many machines and structures are exposed to very high-temperature environments, which has caused various types of thermal load in them. These conditions have led to focused studies on thermal stresses in structures. Heat exchangers are among the structures in which the temperature difference causes thermal stress. In this paper, “finite volume” and “finite element” methods are used to solve flow equations and thermal stress equations in solids, respectively. In addition, the effect of changes in the shape of the annular finned pipe on the thermal stresses in the heat exchanger is investigated. The study results on changing the pipe shape from circular to elliptical show that by changing the pipe shape, the thermal stress in the fin can be significantly reduced; for instance, in the cases reviewed in this paper, the thermal stress has decreased by 9%. Furthermore, the results of thermal stress show that the Maximum Effective Stress point, both before and after changing the shape, is still located at the fin’s base. So, according to the results of this study, examining the effect of pipe shape changing on thermal stress is an imperative measure when designing heat exchangers.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41373488","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}
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