S. Salimon, G. Adepoju, I. Adebayo, S. O. Ayanlade
Shunt Capacitor (SC) integration in radial distribution networks is a method utilized to minimize power losses and huge voltage drops. In other to obtain these maximum benefits, they should be optimally allocated. To this effect, researchers have used various optimization methods for solving SC allocation problems but most have not considered how the penetration level of SC into the radial distribution system affects these benefits. The goal of the paper, therefore, is to determine the most sensitive buses to reactive compensation and investigate the effect of the penetration level of SC on the techno-economic benefits. Load flow was performed for the base case to determine the steady-state performance of the system and the most sensitive buses were selected using New Voltage Stability Index (NVSI) technique. The size of the SC was increased in step of these buses, in turn, to determine SC penetration level impact on the techno-economic benefits. The approach was implemented on IEEE 33-bus and practical Nigerian radial distribution networks. The results showed that appropriate penetration of SC on networks leads to reduction of power losses, voltage profile improvement as well cost reduction resulting in high net savings.
{"title":"Impact of shunt capacitor penetration level in radial distribution system considering techno-economic benefits","authors":"S. Salimon, G. Adepoju, I. Adebayo, S. O. Ayanlade","doi":"10.4314/njtd.v19i2.1","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.1","url":null,"abstract":"Shunt Capacitor (SC) integration in radial distribution networks is a method utilized to minimize power losses and huge voltage drops. In other to obtain these maximum benefits, they should be optimally allocated. To this effect, researchers have used various optimization methods for solving SC allocation problems but most have not considered how the penetration level of SC into the radial distribution system affects these benefits. The goal of the paper, therefore, is to determine the most sensitive buses to reactive compensation and investigate the effect of the penetration level of SC on the techno-economic benefits. Load flow was performed for the base case to determine the steady-state performance of the system and the most sensitive buses were selected using New Voltage Stability Index (NVSI) technique. The size of the SC was increased in step of these buses, in turn, to determine SC penetration level impact on the techno-economic benefits. The approach was implemented on IEEE 33-bus and practical Nigerian radial distribution networks. The results showed that appropriate penetration of SC on networks leads to reduction of power losses, voltage profile improvement as well cost reduction resulting in high net savings.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48008155","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 June 2018, iCog Labs held its second annual robosoccer competition which featured groups of humanoid robots playing soccer against each other. The authors were members of a team called upon to represent Nigeria with the University of Lagos at the competition which took place in Ethiopia. The work here presents a review of the approach taken to address the problem of automating robot coordination in real-world soccer applications. The design methodology relies on the Robot Operating System (ROS) as the platform upon which an asynchronous communication network between each robot and a central server is built. On the network, each robot is a node that consists of sub nodes for object detection and motion control. For object detection the work makes use of the you only look once (YOLO)v2 deep learning algorithm, and a simple decision-making algorithm for controlling vcv the robot based on the objects detected is devised. To quantify the object detection results, the common objects in context (COCO) evaluation metric is used. The results indicate an average recall and precision of 84% across different IOU. For qualitative results on the robot coordination in the ball’s direction, a reference to the open-source implementation of the work has been provided.
2018年6月，iCog实验室举办了第二届年度机器人足球比赛，比赛中，几组人形机器人相互踢足球。这些作者是应邀代表尼日利亚与拉各斯大学参加在埃塞俄比亚举行的比赛的一个小组的成员。这里的工作介绍了在现实世界的足球应用中解决自动化机器人协调问题的方法。设计方法依赖于机器人操作系统(ROS)作为平台，在该平台上建立了每个机器人与中央服务器之间的异步通信网络。在网络中，每个机器人都是一个节点，该节点由用于物体检测和运动控制的子节点组成。在目标检测方面，利用YOLO (you only look once)v2深度学习算法，设计了一种基于检测到的目标控制机器人vcv的简单决策算法。为了量化目标检测结果，使用了上下文公共对象(common objects in context, COCO)评价指标。结果表明，不同借据的平均查全率和查准率为84%。对于机器人在球方向上的协调的定性结果，提供了工作的开源实现参考。
{"title":"Object detection for robot coordination in robotics soccer","authors":"C. Yinka-banjo, O. Ugot, E. Ehiorobo","doi":"10.4314/njtd.v19i2.5","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.5","url":null,"abstract":"In June 2018, iCog Labs held its second annual robosoccer competition which featured groups of humanoid robots playing soccer against each other. The authors were members of a team called upon to represent Nigeria with the University of Lagos at the competition which took place in Ethiopia. The work here presents a review of the approach taken to address the problem of automating robot coordination in real-world soccer applications. The design methodology relies on the Robot Operating System (ROS) as the platform upon which an asynchronous communication network between each robot and a central server is built. On the network, each robot is a node that consists of sub nodes for object detection and motion control. For object detection the work makes use of the you only look once (YOLO)v2 deep learning algorithm, and a simple decision-making algorithm for controlling vcv the robot based on the objects detected is devised. To quantify the object detection results, the common objects in context (COCO) evaluation metric is used. The results indicate an average recall and precision of 84% across different IOU. For qualitative results on the robot coordination in the ball’s direction, a reference to the open-source implementation of the work has been provided.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43172341","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}
O. M. Buraimoh, G. Adewumi, N. Akinyemi, O. Amund, M. O. Ilori, F. C. Michel Jr.
Indiscriminate disposal of wood shavings and sawdust into the Lagos lagoon usually constitute environmental hazard and varying degree of threats to marine biotic communities. In this study we applied terminal-restriction fragment length polymorphism (T-RFLP) and illumina sequencing of 16S ribosomal RNA gene, to describe the microbial ecology of decomposing wood wastes in the Lagos lagoon, Nigeria. The terminal restriction fragments (TRFs) generated corresponds to over 100 bacterial genera and numerous uncultured bacterial clones. Phylogenetic analysis of the TRFs of 16S rRNA gene sequences and cultured bacterial sequences established genetic relatedness and divergent relationships. T-RFLP in combination with illumina sequencing platform identified bacterial species (Acinetobacter sp., Clostridium sp., Planctomyces sp., Escherichia coli, Pantoea agglomerans, Dyella japonica, Ochrobactrum sp., Prevotella sp., Runella slithyformis, Enterobacter aerogenes, Gordonia amicalis, Klebsiella sp., Thalassospira sp. and Serratia sp.) not previously accounted for in culture-dependent analysis. Bacterial strains such as Ruminococcus flavefaciens, Fibrobacter succinogenes, Simiduia agarivorans, Microbulbifer sp. and Cellulomonas fimi further identified in illumina sequences were found to be involved in the biodegradation of lignin and lignin derivatives. Hence, understanding of the diverse autochthonous microbiota of decomposing wood wastes in the Lagos lagoon is essential in the development of effective biotechnology programme, to tackling the menace of sawdust pollution.
{"title":"Analysis of decomposing wood wastes in the Lagos Lagoon using terminal-restriction fragment length polymorphism and illumina sequencing platform","authors":"O. M. Buraimoh, G. Adewumi, N. Akinyemi, O. Amund, M. O. Ilori, F. C. Michel Jr.","doi":"10.4314/njtd.v19i2.3","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.3","url":null,"abstract":"Indiscriminate disposal of wood shavings and sawdust into the Lagos lagoon usually constitute environmental hazard and varying degree of threats to marine biotic communities. In this study we applied terminal-restriction fragment length polymorphism (T-RFLP) and illumina sequencing of 16S ribosomal RNA gene, to describe the microbial ecology of decomposing wood wastes in the Lagos lagoon, Nigeria. The terminal restriction fragments (TRFs) generated corresponds to over 100 bacterial genera and numerous uncultured bacterial clones. Phylogenetic analysis of the TRFs of 16S rRNA gene sequences and cultured bacterial sequences established genetic relatedness and divergent relationships. T-RFLP in combination with illumina sequencing platform identified bacterial species (Acinetobacter sp., Clostridium sp., Planctomyces sp., Escherichia coli, Pantoea agglomerans, Dyella japonica, Ochrobactrum sp., Prevotella sp., Runella slithyformis, Enterobacter aerogenes, Gordonia amicalis, Klebsiella sp., Thalassospira sp. and Serratia sp.) not previously accounted for in culture-dependent analysis. Bacterial strains such as Ruminococcus flavefaciens, Fibrobacter succinogenes, Simiduia agarivorans, Microbulbifer sp. and Cellulomonas fimi further identified in illumina sequences were found to be involved in the biodegradation of lignin and lignin derivatives. Hence, understanding of the diverse autochthonous microbiota of decomposing wood wastes in the Lagos lagoon is essential in the development of effective biotechnology programme, to tackling the menace of sawdust pollution.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46738530","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 need to decentralize power generation and decarbonize the earth in order to have a sustainable global economy are the major reasons for the development of this paper. Considering the flaws of grid-connected power system, the autonomous system becomes a better alternative in rural and isolated areas. Analysis of stand-alone single-phase Asynchronous generator based on d-q model in a stationary reference frame is presented. Asynchronous generator does not have the capability to produce reactive power necessary for excitation and this must be provided by external means. Capacitive method has been considered in this paper due to its simplicity and its economic viability. The effects of magnetic saturation in the airgap has been considered by using the nonlinear relationship between the magnetizing inductance and the magnetizing current of the machine. Under this approach, the mutual inductance varies continuously. The results have shown that steady state condition of the generated voltage is not fixed but depends on the suitable combination of excitation capacitance and the rotor speed.
{"title":"Capacitively-excited single-phase asynchronous generator for autonomous applications","authors":"K. Sanusi, L. Olatomiwa, A. Mohammed, K. A. Sodiq","doi":"10.4314/njtd.v19i2.4","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.4","url":null,"abstract":"The need to decentralize power generation and decarbonize the earth in order to have a sustainable global economy are the major reasons for the development of this paper. Considering the flaws of grid-connected power system, the autonomous system becomes a better alternative in rural and isolated areas. Analysis of stand-alone single-phase Asynchronous generator based on d-q model in a stationary reference frame is presented. Asynchronous generator does not have the capability to produce reactive power necessary for excitation and this must be provided by external means. Capacitive method has been considered in this paper due to its simplicity and its economic viability. The effects of magnetic saturation in the airgap has been considered by using the nonlinear relationship between the magnetizing inductance and the magnetizing current of the machine. Under this approach, the mutual inductance varies continuously. The results have shown that steady state condition of the generated voltage is not fixed but depends on the suitable combination of excitation capacitance and the rotor speed.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41423033","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}
ABSTRACT: Effective lubrication during metal working is critical to mitigating undesirable tool wear and poor surface finish of formed components. This paper investigated the physicochemical characteristics of cashew nut-shell-liquid (CNSL) with a view of determining its suitability for the development of an eco-friendly lubricant used in metal forming. The cashew nut shell oil (CNSO) was extracted by soxhlet method and characterised to determine its physicochemical properties including density, free fatty acid (FFA), and viscosity. In addition, the saponification value, iodine value, pH, flash point and friction coefficient were determined using relevant analytical tools. The results showed that CNSL yield from soxhlet solvent extraction is 45.6%, which is adjudged to be relatively substantial with regard to other extraction processes. Furthermore, the CNSL exhibited critical lubrication characteristics in terms of density (0.94 g/cm3), moisture content (3.96%), acid value (11.32 mg.KOH/g), FFA (3.7%), ester value (127.92 mg.KOH/g), saponification value (139.24 mg.KOH/g), pH value (4.61), iodine value (40.21 gI2/100 g), viscosity at 100 oC (14.12 Pa.s), friction coefficient (0.001) and flash point of 286.63 oC. Given these outcomes in comparison with commercial Chevron soluble oil, it is concluded that CNSL is suitable for use as a viable metal forming lubrication fluid.
{"title":"Extraction and physicochemical characterization of cashew nut-shell liquid in metal forming","authors":"O. Sekunowo, G. U. Uduh","doi":"10.4314/njtd.v19i2.2","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.2","url":null,"abstract":"ABSTRACT: Effective lubrication during metal working is critical to mitigating undesirable tool wear and poor surface finish of formed components. This paper investigated the physicochemical characteristics of cashew nut-shell-liquid (CNSL) with a view of determining its suitability for the development of an eco-friendly lubricant used in metal forming. The cashew nut shell oil (CNSO) was extracted by soxhlet method and characterised to determine its physicochemical properties including density, free fatty acid (FFA), and viscosity. In addition, the saponification value, iodine value, pH, flash point and friction coefficient were determined using relevant analytical tools. The results showed that CNSL yield from soxhlet solvent extraction is 45.6%, which is adjudged to be relatively substantial with regard to other extraction processes. Furthermore, the CNSL exhibited critical lubrication characteristics in terms of density (0.94 g/cm3), moisture content (3.96%), acid value (11.32 mg.KOH/g), FFA (3.7%), ester value (127.92 mg.KOH/g), saponification value (139.24 mg.KOH/g), pH value (4.61), iodine value (40.21 gI2/100 g), viscosity at 100 oC (14.12 Pa.s), friction coefficient (0.001) and flash point of 286.63 oC. Given these outcomes in comparison with commercial Chevron soluble oil, it is concluded that CNSL is suitable for use as a viable metal forming lubrication fluid.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48465698","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}
Losses such as rotor iron and stator iron losses, magnet eddy current loss, as well as efficiency of a double stator permanent magnet machine having varying rotor pole numbers is estimated and presented in this study. This current investigation would be vital for electrical machine designers in quantifying the amount of losses in the various sections of a given double stator electric machine and as well provide better insight on resulting output efficiency of the machine. Time-stepping finite element analysis (TS-FEA) procedure is adopted in the calculations using ANSYS-MAXWELL simulation software. The compared machines having the same stator teeth/pole number (Ps) and different rotor pole (Pr) numbers are designated as: 6Ps/10Pr, 6Ps/11Pr, 6Ps/13Pr and 6Ps/14Pr. The predicted total loss values at rated current and operating base speed is 13.02 Watts, 13.13 Watts, 13.539 Watts, 13.537 Watts, from the 6Ps/10Pr, 6Ps/11Pr, 6Ps/13Pr and 6Ps/14Pr machine types, respectively. The corresponding efficiency of the machine types at rated working conditions is: 81.76%, 88.17%, 86.95% and 78.61%, respectively. The results show that magnitude of losses in a given machine would largely depend upon factors such as number of rotor poles and hence, the machine’s operating speed, electric loading and angular rotor position of the machine, etc. It is also found that the number of loss waveform cycles (Nc) in an electric revolution of the investigated machine would depend upon its stator and rotor arrangements. The most performing compared machine types are the ones that have 11- and 13-rotor pole numbers, while the least amount of efficiency is obtained from the machine type that has 14-rotor pole number. Above all, the 6Ps/10Pr and 6Ps/14Pr are characterized with high amount of pulsations or ripples and this is detrimental to the overall performance of the machines.
{"title":"Estimation of losses and efficiency of double-stator switched flux permanent magnet machines","authors":"C. Awah, O. Okoro, A. Onah, G. Diyoke","doi":"10.4314/njtd.v19i2.7","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.7","url":null,"abstract":"Losses such as rotor iron and stator iron losses, magnet eddy current loss, as well as efficiency of a double stator permanent magnet machine having varying rotor pole numbers is estimated and presented in this study. This current investigation would be vital for electrical machine designers in quantifying the amount of losses in the various sections of a given double stator electric machine and as well provide better insight on resulting output efficiency of the machine. Time-stepping finite element analysis (TS-FEA) procedure is adopted in the calculations using ANSYS-MAXWELL simulation software. The compared machines having the same stator teeth/pole number (Ps) and different rotor pole (Pr) numbers are designated as: 6Ps/10Pr, 6Ps/11Pr, 6Ps/13Pr and 6Ps/14Pr. The predicted total loss values at rated current and operating base speed is 13.02 Watts, 13.13 Watts, 13.539 Watts, 13.537 Watts, from the 6Ps/10Pr, 6Ps/11Pr, 6Ps/13Pr and 6Ps/14Pr machine types, respectively. The corresponding efficiency of the machine types at rated working conditions is: 81.76%, 88.17%, 86.95% and 78.61%, respectively. The results show that magnitude of losses in a given machine would largely depend upon factors such as number of rotor poles and hence, the machine’s operating speed, electric loading and angular rotor position of the machine, etc. It is also found that the number of loss waveform cycles (Nc) in an electric revolution of the investigated machine would depend upon its stator and rotor arrangements. The most performing compared machine types are the ones that have 11- and 13-rotor pole numbers, while the least amount of efficiency is obtained from the machine type that has 14-rotor pole number. Above all, the 6Ps/10Pr and 6Ps/14Pr are characterized with high amount of pulsations or ripples and this is detrimental to the overall performance of the machines.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44285316","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 influence of channel shape on a combined heat sink of three different channel forms is investigated numerically in this work. The channel shapes considered were the trapezoidal, inverse trapezoidal and hexagonal microchannel shapes. The goal of this study was to compare and identify the combined microchannel shape that performed best under conditions of high uniform heat flux. The thermal performance of the combined heat sink was assessed using two criteria: lowest maximum temperature and lowest temperature elevation on the bottom of the combined heat sink where heat is applied. The uniform heat flux applied to the bottom of the combined heat sink was elevated from 100 𝑊/𝑐𝑚2 to1000 𝑊/𝑐𝑚2. For the maximum heat flux of 1000 𝑊/𝑐𝑚2and lowest pressure drop of 10kPa considered, in terms of temperature elevation on the bottom of the heat sink where heat is applied, the trapezoidal combined microchannel heat sink outperformed other channel shapes. When the minimized overall maximum temperature is considered, the hexagonal combined microchannel heat sink was the best combined heat sink.
{"title":"Numerical investigation of thermal performance of a combined heat sink with various microchannel shapes","authors":"A. Lawal, O. Adewumi, O. T. Olakoyejo","doi":"10.4314/njtd.v19i2.9","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.9","url":null,"abstract":"The influence of channel shape on a combined heat sink of three different channel forms is investigated numerically in this work. The channel shapes considered were the trapezoidal, inverse trapezoidal and hexagonal microchannel shapes. The goal of this study was to compare and identify the combined microchannel shape that performed best under conditions of high uniform heat flux. The thermal performance of the combined heat sink was assessed using two criteria: lowest maximum temperature and lowest temperature elevation on the bottom of the combined heat sink where heat is applied. The uniform heat flux applied to the bottom of the combined heat sink was elevated from 100 𝑊/𝑐𝑚2 to1000 𝑊/𝑐𝑚2. For the maximum heat flux of 1000 𝑊/𝑐𝑚2and lowest pressure drop of 10kPa considered, in terms of temperature elevation on the bottom of the heat sink where heat is applied, the trapezoidal combined microchannel heat sink outperformed other channel shapes. When the minimized overall maximum temperature is considered, the hexagonal combined microchannel heat sink was the best combined heat sink.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45026475","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}
Fossil fuels are very important fuel for electricity generation. These fuels are limited in availability and produce emissions that are hazardous to the environment, hence, their usage are required to be minimized. The power system analysis that minimizes the consumption of fossil fuels by generating units in a power system is termed Generation Dispatch. This is a power system planning problem that need to be solved accurately considering different factors and constraints. The Nigerian power system was deregulated more than a decade and half ago and a critical review of its Generation Dispatch Problem (GDP) solutions was carried out in this work. The review x-rayed the types of GDP, factors and/or constraints considered, and the optimization method employed for GDP solutions of Nigerian power system. Results of the review revealed that not much has been done and suggested research directions for work on the GDP of Nigerian power system.
{"title":"Optimization approaches to generation dispatch problems: Review of Nigerian power system","authors":"M. A. Tijani, G. Adepoju, M. Okelola","doi":"10.4314/njtd.v19i2.","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.","url":null,"abstract":"Fossil fuels are very important fuel for electricity generation. These fuels are limited in availability and produce emissions that are hazardous to the environment, hence, their usage are required to be minimized. The power system analysis that minimizes the consumption of fossil fuels by generating units in a power system is termed Generation Dispatch. This is a power system planning problem that need to be solved accurately considering different factors and constraints. The Nigerian power system was deregulated more than a decade and half ago and a critical review of its Generation Dispatch Problem (GDP) solutions was carried out in this work. The review x-rayed the types of GDP, factors and/or constraints considered, and the optimization method employed for GDP solutions of Nigerian power system. Results of the review revealed that not much has been done and suggested research directions for work on the GDP of Nigerian power system.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46038463","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}
Pharming scams are carried out by exploiting the DNS as the main weapon while phishing attacks employ spoofed websites that appear to be legitimate to internet users. Phishing makes use of baits such as fake links but pharming leverages and negotiates on the DNS server to move and redirect internet users to a fake and simulated website.Having seen several challenges through pharming resulting into vulnerable websites, personal emails and accounts on social media, the usage and reliability on internet calls for caution. Against this backdrop, this work aims at enhancing pharming detection strategies by adopting machine learning classification algorithms. To further obtain the best classification results, an ensemble learning approach was adopted. The algorithms used include K-Nearest Neighbors (KNN), Decision Tree, Random Forest, Gaussian Naive Bayes, Logistic Regression, Support Vector Machine, Adaptive Boosting, Gradient Boosting, and Extra Trees Classifier. During the testing process, the classifiers were tested against four popular metrics: accuracy, recall, precision, F1 score, and Log loss. The results demonstrate the performance of all algorithms used, as well as their relationships. The ensemble model that included Logistic Regression, K-Nearest Neighbors, Decision Tree, Support Vector Machine, Gradient Boosting Classifier, AdaBoost Classifier, Extra Trees Classifier, and Random Forest produced the best results after evaluating them on the two datasets. Random Forest Classifiers showed a better performance of the classifiers, with mean accuracies of 0.932 and 0.939, respectively for each of the datasets when compared to 0.476 and 0.519 obtained for Naive Bayes.
{"title":"Identification of pharming in communication networks using ensemble learning","authors":"N. Azeez, S. Oladele, O. Ologe","doi":"10.4314/njtd.v19i2.10","DOIUrl":"https://doi.org/10.4314/njtd.v19i2.10","url":null,"abstract":"Pharming scams are carried out by exploiting the DNS as the main weapon while phishing attacks employ spoofed websites that appear to be legitimate to internet users. Phishing makes use of baits such as fake links but pharming leverages and negotiates on the DNS server to move and redirect internet users to a fake and simulated website.Having seen several challenges through pharming resulting into vulnerable websites, personal emails and accounts on social media, the usage and reliability on internet calls for caution. Against this backdrop, this work aims at enhancing pharming detection strategies by adopting machine learning classification algorithms. To further obtain the best classification results, an ensemble learning approach was adopted. The algorithms used include K-Nearest Neighbors (KNN), Decision Tree, Random Forest, Gaussian Naive Bayes, Logistic Regression, Support Vector Machine, Adaptive Boosting, Gradient Boosting, and Extra Trees Classifier. During the testing process, the classifiers were tested against four popular metrics: accuracy, recall, precision, F1 score, and Log loss. The results demonstrate the performance of all algorithms used, as well as their relationships. The ensemble model that included Logistic Regression, K-Nearest Neighbors, Decision Tree, Support Vector Machine, Gradient Boosting Classifier, AdaBoost Classifier, Extra Trees Classifier, and Random Forest produced the best results after evaluating them on the two datasets. Random Forest Classifiers showed a better performance of the classifiers, with mean accuracies of 0.932 and 0.939, respectively for each of the datasets when compared to 0.476 and 0.519 obtained for Naive Bayes.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44555026","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}
Flare gas utilization has been a topic of discussion among stakeholders of the Nigerian Petroleum Industry and one of the simplest technical and commercial strategies is to send these gases to an existing gas pipeline with spare capacity. Peculiarities of flare gas can pose different challenges but the feasibility of the project depends on exogenous factors such as proximity to gas pipeline and availability of markets. In this work, an energy integrated methanol-based gas processing method for treatment and recovery of Liquefied Petroleum Gas (LPG) is presented using a high flaring intensity Nigerian Marginal oilfield close to an existing gas pipeline. A capacity of 60 MMscfd was determined using the flaring profile of the oilfield and a propane refrigeration system was selected as the cold process. ASPEN HYSYS V9 Cubic Plus Association (CPA) equation of state was used to optimally predict methanol (used as a hydrate inhibitor) partitioning in the methanol-hydrocarbon system. This process produced 57.15 MMscfd of natural gas, 163.7 tonne/day of LPG, and 33.19 tonne/day of stabilized condensate in line with Nigerian gas transport code specifications. The equipment count in comparison to other gas processing schemes, operational flexibility, and ease of scalability indicates that it is an economic technology that will be well suited for solving the gas flare scenario in the Niger Delta region by converting these wasted gas into more useful products.
火炬气的利用一直是尼日利亚石油工业利益相关者讨论的话题，最简单的技术和商业策略之一是将这些气体输送到具有备用容量的现有天然气管道。火炬气的特殊性可能会带来不同的挑战，但项目的可行性取决于外部因素，如靠近天然气管道和市场的可用性。在这项工作中，利用靠近现有天然气管道的尼日利亚边际油田的高燃烧强度，提出了一种用于液化石油气（LPG）处理和回收的能量集成甲醇基天然气处理方法。使用油田的燃烧剖面确定了60 MMscfd的容量，并选择丙烷制冷系统作为冷工艺。ASPEN HYSYS V9 Cubic Plus Association（CPA）状态方程用于最佳预测甲醇（用作水合物抑制剂）在甲醇-烃系统中的分配。该工艺生产了57.15 MMscfd的天然气、163.7吨/天的液化石油气和33.19吨/天稳定凝析油，符合尼日利亚天然气运输规范。与其他天然气处理方案相比，设备数量、操作灵活性和易于扩展性表明，这是一种经济技术，非常适合通过将这些废气转化为更有用的产品来解决尼日尔三角洲地区的天然气火炬情况。
{"title":"Production of natural gas and liquefied petroleum gas from flare gas using methanol based process","authors":"P. U. Ndunagu, O. Joel, O. Akuma, E. E. Alaike","doi":"10.4314/njtd.v19i1.7","DOIUrl":"https://doi.org/10.4314/njtd.v19i1.7","url":null,"abstract":"Flare gas utilization has been a topic of discussion among stakeholders of the Nigerian Petroleum Industry and one of the simplest technical and commercial strategies is to send these gases to an existing gas pipeline with spare capacity. Peculiarities of flare gas can pose different challenges but the feasibility of the project depends on exogenous factors such as proximity to gas pipeline and availability of markets. In this work, an energy integrated methanol-based gas processing method for treatment and recovery of Liquefied Petroleum Gas (LPG) is presented using a high flaring intensity Nigerian Marginal oilfield close to an existing gas pipeline. A capacity of 60 MMscfd was determined using the flaring profile of the oilfield and a propane refrigeration system was selected as the cold process. ASPEN HYSYS V9 Cubic Plus Association (CPA) equation of state was used to optimally predict methanol (used as a hydrate inhibitor) partitioning in the methanol-hydrocarbon system. This process produced 57.15 MMscfd of natural gas, 163.7 tonne/day of LPG, and 33.19 tonne/day of stabilized condensate in line with Nigerian gas transport code specifications. The equipment count in comparison to other gas processing schemes, operational flexibility, and ease of scalability indicates that it is an economic technology that will be well suited for solving the gas flare scenario in the Niger Delta region by converting these wasted gas into more useful products.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43246193","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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