Nigerian Journal of Technology

SETTLEMENT, SLOPE STABILITY AND SEEPAGE ANALYSES BY NUMERICAL MODELLING METHOD AND THEIR APPLICATIONS IN PRACTICE

2023-07-31T21:03:54+00:00

The encountered situations during the design process of a gully erosion control site in Kano State are discussed in this article. The project was to design a rectangular concrete lined drainage channel with short side walls to efficiently convey flood water and prevent embankment erosion. Because of the embankment depth and soil type on the site which are mostly silty/clayey sand, settlement of the huge concrete channel, seepage and the unprotected embankment slope were issues of major concern. Settlement, slope stability and seepage analyses and designs were some of the several activities undertaken for the project. The anticipated total settlement prediction was performed by numerical simulation from which the differential settlement was then calculated. The prediction of the safety factor to determine the stability of the slope was performed by numerical simulation using SLOPE/W. The hydraulic velocity and rate of seepage prediction was performed by numerical modelling using SEEP/W. The use of numerical technique was specifically recommended by the consultants of the funder of the project, the World Bank. It was observed that numerical modelling technique provided accurate results of settlement, factor of safety, hydraulic velocity and rate of seepage and was therefore recommended for both research and practical applications.

GROUNDWATER QUALITY ASSESSMENT OF ABA URBAN AREA

2023-06-24T16:26:48+00:00

This work presents groundwater quality assessment of Aba Urban area and its sources of Contaminants within Aba Urban Area. Aba area was divided into nine parts using a 3x3 grid. Water samples were taken from each of these 9 parts of Aba. Five water samples were taken from household boreholes while four samples were taken from boreholes drilled and cased at the remaining four parts in the course of carrying out this research. Site and laboratory tests were conducted to determine the values water parameters in the samples. The parameters analysed in the laboratory include the Phosphate, ammonium, Lead, cadmium, Manganese, Copper, Mercury, Chromium, and magnesium, Electric conductivity (EC), Dissolved oxygen (DO), Total dissolved solid (TDS), Acidity, Turbidity, Alkalinity, oxidation-reduction potential (ORP), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and E-Coli. It was discovered that more than 75% of the water samples are contaminated by E-Coli. Umuagu sample has Manganese value of 0.775mg/l. This more than the limiting value of 0.4mg/l. The values 252, 524 and 472 mg/l of Magnesium in samples from Estate, Abia Polytechnic and Osisio Ngwa respectively are more than the limiting value of 150mg/l. The DO (mg/l) values of 6,4 and 9 from Ariaria Junction and Abia Polytechnic are outside the range limiting of 6.5mg/l – 8.0 mg/l. The values of TDS, ORP and BOD recorded in all the samples are below the limiting values of 600 mg/l, 357 mV and 1mg/l respectively.

SYNTHESIS AND CHARACTERIZATION OF ALKYD RESINS FROM RUBBER SEED/SOYBEAN OIL BLENDS

2023-05-28T03:00:53+00:00

The polymerization and properties of environmentally friendly resin binders applicable in the surface-coating industry were studied. Rubber seed oil (RSO) and RSO blended with 10% and 20% soybean oil (SBO)-based alkyd resins were synthesized by alcoholysis-polyesterification of the oil with glycerol and phthalic anhydride. Physicochemical properties (such as colour, specific gravity, acid value, saponification value, iodine value, and drying schedule) of the alkyd resins were determined to establish the possible industrial potential of the resins. The saponification value and iodine value ranged from 250.19 mgKOH/g to 279.55 mgKOH/g and 29.58 gI₂/100g to 33.77 gI₂/100g respectively. The drying schedule and chemical resistance of the blended alkyd resins to water, salts, acids, and alkalis were also studied. The blended resins were found to be resistant to water, salt, and acid media, except for alkali media. The colour properties were enhanced as the percentage of the blend increased. FT-IR spectroscopic study of the oil and alkyd resin samples further corroborates our findings. Therefore, the potential of rubber seed oil blended with soybean oil to produce light-coloured alkyd resins could be exploited as raw materials for the Nigerian surface coating industry.

DEVELOPMENT OF A MULTIGENERATION SYSTEM WITH INTEGRATED HYDROGEN PRODUCTION: A TYPICAL ANALYSIS

2023-03-30T23:56:27+00:00

Rise in demand for energy and emission from fossil fuels has become a thing of concern to researchers and Engineers. It is one thing to provide the energy needed by the society, and another to produce a clean and eco-friendly power supply. In this study, a thermodynamic and economic modelling of a solar-driven multigeneration power plant (MGPP) integrated with a PEM Electrolyzer for hydrogen production is examined. The performance indicators considered include energy and exergy efficiencies, net work, energetic and exergetic COP, cooling rate. Results of the thermodynamic analysis show that the energy and exergy efficiencies excluding the fuel cell was 28.57% and 34.79% respectively; when the fuel cell was incorporated, the energy and exergy efficiencies were respectively 24.45% and 34.63%. The energetic and exegetic COP was 0.609 and 0.281 respectively. Additionally, net work, cooling rate, and hydrogen production were respectively 52.75kW, 86.83kW, and 0.0114kg/s. The economic analysis indicates a unit cost of electricity (UCOE) at $0.025/kWh, a life cycle cost of $0.1097 and a payback period of 4years was achieved. The developed multigeneration system is technically and economically viable with net zero CO₂ emissions. It can also serve as an alternative option to fossil-powered plants and sectors with less energy demand.

DEVELOPMENT OF QUEUE MANAGEMENT MODEL FOR EFFECTIVE SERVICE DELIVERY IN AUTOMOBILE REPAIR SHOPS

2023-06-06T18:44:00+00:00

In this study, a queue management model/software was developed for automobile repair shops. This software minimizes both waiting time of customers, and idle time of workers. The software groups all jobs done in an automobile repair shop into three sections: mechanical, electrical and air conditioning (A/C) sections. The developed software prioritizes all jobs performed in a typical automobile repair shop in terms of urgency, using the ‘shortest processing time’ scheduling approach. The jobs are then ranked and assigned to workers based on number of available workstations. Also, expected time of delivery of the job is estimated by the software. The software was tested using data obtained over a two weeks period and percentage reduction in waiting time was found to range between: 0.889-0.122, 0.895-0.25 and 1-0.167 for the mechanical, electrical and A/C sections respectively. In the mechanical section, servicing/replacement of piston and rings and changing/servicing of gear box were discovered to be the jobs with maximum delivery time (15 hrs) while changing of engine belt was seen as the job with the least delivery time (0.3 hrs). For the electrical section, changing of alternator, with delivery time of 3 hrs 30 mins and changing of headlamp and fuse breakage with delivery time of 0.15 hrs are the jobs with maximum and minimum delivery times respectively. For the A/C section, changing of freezer with delivery time of 10 hrs and refilling of gas with delivery time of 0.10 hrs are the maximum and minimum respectively. Implementation of this research will reduce time wastage experienced by customers, idle time at service facilities, frustration caused by unnecessary queue, and encourage allocation of resources accordingly.

CHEMICAL AND MINERALOGICAL PROPERTIES OF LEJJA NSUKKA IRON ORE DEPOSITS

2023-08-23T17:25:58+00:00

The ore deposits obtained from Dunoka, Amankwo and Umuakpo in Lejja Nsukka were found to be iron silicate in nature. They were analysedby XRD, XRF, AAS and the ores were found to contain 60.59% Fe, 64.81%Fe and 64.67%Fe respectively. These ores when compared to those iron ore producing nations, they were classified as medium-grade iron ore. Other elements like titanium, magnesium and manganese were present and could be mined for commercial use. Chemical analysis of the ore samples showed that traces of phosphorous of ≤ 0.0079% and were free from the deleterious elements, sulphur and arsenic.

OPTIMIZATION OF LEACHING PARAMETERS FOR THE EXTRACTION OF COPPER FROM HEMATITE-DOMINATED COPPER ORE USING RESPONSE SURFACE METHODOLOGY (RSM)

2023-06-24T23:18:38+00:00

The optimization of recovery of copper from Akiri hematite-dominated copper ore using hydrometallurgy was investigated in this study. The Akiri copper ore deposit hosts a high-grade copper mineral from which copper metal can be extracted. However, the ore is dominated by gangue minerals that need to be mechanically reduced for efficient copper recovery. The purpose of this study is to optimize the extraction of the metal from hematite-dominated copper ore. The experiments that were carried out in the course of this study include crushing, pulverization,mineralogical and chemical characterizations of the sample and sulpheric acid leaching. Response surface methodology was used to optimize the system parameters namely;temperature, concentration of the leachant and contact time so that an efficient method will be developed for the extraction of copper.Chalcopyrite, covellite and cuprite are the copper minerals while the gangues minerals were quartz ,mica, hematite,etc.on the characterization of the copper ore. The major oxides in the ore are hematite ,copper oxide and silica and revealed that the ore contains 4.61% copper and 65.8% iron. Effect of three independent factors like concentration ,temperature and contact time for copper extraction from the hematite-dominated copper ore was studied.Central composite design method was applied to the proposed quadratic model that connect the factors used for best copper extraction at the best process condition. The work shows that concentration of the acid was the best efficient factor for copper extraction compare to temperature and contact time. This may be as a result of high value of F-statistics for the concentration of the leachant, which effects to high level of copper extraction.Experimental and predicted values for weight loss from the copper ore were obtained as 39.10% and 39.03% at optimum conditions, respectively. The optimum conditions of 1.5M acid concentration, 90^oC reaction temperature and 90minutes contact time were obtained and from which 6.64%Cu at recovery of 92.0% and 2.31%Fe was obtained without stirring. Also, the ore was subjected to leaching with stirring at 400rpm with the optimum conditions obtained to know the effect. The grade obtained was 7.84%Cu at recovery of 83.51% and iron content 5.47%. This shows that leaching without stirring is the best option against leaching with stirring to extract the copper and to reduce the iron and other gangues contents in the copper ore.The activation energies were estimated as 13.20kJ/mol and 22.67kJ/mol for liquid film diffusion and diffusion product layer respectively, the values indicate that the leaching rate is controlled by diffusion process.

COMPARATIVE ANALYSIS OF ABRASIVE WEAR BETWEEN ALUMINIUM ALLOY AND MILD STEEL IN A PIN-ON-DISC TRIBOLOGICAL TEST

2023-09-04T13:57:14+00:00

A comparative analysis of the abrasive wear of aluminium alloy and mild steel on the pin-on-disc wear test machine has been successfully carried out. An investigation on the effects of wear, stress and strain on the aluminium alloy and the mild steel was conducted. The wear test carried out determined the difference between rate of wear of the aluminium alloy and the mild steel. The input parameters applied in determining the wear rate were time of wear, sliding distance, track diameter of the disc and mass difference before and after the experiment. The finite element analysis developed the stress and elastic strain distribution obtained on the application of 2 kg load (20 N) on the aluminium alloy and mild steel specimen. The equivalent (Von Mises) stress distribution in mild steel had a maximum stress value of 0.023625 Mpa and minimum stress of 1.444×10^-5Mpa while that of the aluminium alloy yielded a maximum and minimum stress of 0.0365 Mpa and 8.5×10^-5Mpa respectively. It was evident that the aluminium alloy recorded a higher magnitude of stress than the mild steel. This showed that the aluminium alloy being relatively light was more stressed than the mild steel. It was discovered that the rate of wear was higher in the aluminium alloy than in the mild steel.

A LINEAR MODEL-BASED SIMULATION TOOL FOR ESTIMATING NUMBER OF TRIALS NEEDED FOR UPPER LIMB STROKE RECOVERY IN A GIVEN REHABILITATION SESSION

2023-02-22T13:41:06+00:00

Traditional methods for assessing upper-limb functional outcomes in stroke patients often fail to estimate the number of trials required to achieve performance stability of a chosen kinematic metric. Limited non-model-based studies have attempted to tackle this issue. To bridge this gap, this study utilized an iterative learning algorithm (ILA) in MATLAB, employing linear models to represent the muscle dynamics and forearm extension of impaired patients. The reference task space trajectory was set as a straight-line point-point trajectory within a range of 0 - 0.2828m. By using the root mean square error (RMSE) as a metric for evaluating kinematic accuracy, a maximum kinematic deviation error of 0.01m was imposed with respect to the trajectory by the (ILA). Results indicate that over 16 trials, performance stability was obtained with improvement in deviation error from 0.0168m in the first trial to 0.0060 at sixteen trials. The result obtained is in line with similar non-model studies and our findings inform the potential of ILAs with linear models for estimation of trial numbers required to attain performance stability of a selected kinematic metric (i.e., kinematic accuracy).

USER PAIRING IMPACT ON THE PERFORMANCE OF HYBRID BEAMFORMING NOMA SYSTEM

2023-10-17T06:01:24+00:00

This paper proposes a new user pairing technique for a power domain non-orthogonal multiple access (NOMA) deploying fully connected and sub-connected hybrid beamforming (HBF) structures for a typical urban microcell downlink of line-of-sight (LOS) and non-line-of-sight (NLOS) surroundings. NOMA system’s configurations are set up for two (multiple input single output) users per cluster down-linking base station equipped with 128 antennas. HBF processing adopts phased zero forcing (P-ZF) for both fully connected (HBF-NOMA) structure (FCS) and sub-connected (HBF-NOMA) structure (SCS) precoders’ optimization, and successive interference cancellation zero forcing (SIC-ZF) schemes to optimize the SCS-HBF-NOMA precoder exploiting dynamic power allocation. The new users’ pairing exploits users’ distance to the base station, namely near and far clusters different from the benchmark angle of arrival- based users’ pairing. The proposed users’ pairing and the precoding schemes’ impact are investigated for finite-resolution HBF structures operating in LOS and NLOS surroundings. The execution under New York University (NYU) mmW channel model is explored for two users in a cluster with different angles of arrival. Results show that the users’ pairing based on AoA performs better than the newly proposed users’ pairing. However, the proposed users’ pairing scheme performs better than their corresponding OMA counterparts, which still make them beneficial for multiple access technique and a scenario, where one of the far cluster users need to access the base station for high data rate service and vice versa. Finally, the modified Liang processing scheme for quantizing SCS-HBF-NOMA precoder is capable of mitigating the quantization error arising from the NLOS environment and the nature of sub-connected (HBF) structure under a low SNR regime.

COVID-19 CRISIS ERA; ENGINEERING INTERVENTIONS IN SUB-SAHARAN AFRICA

2023-06-06T18:10:52+00:00

Despite numerous notable contributions by Africans during the Corona Virus Disease (COVID-19) outbreak, little effort has been made to document these contributions in a comprehensive publication. Herein this work, an attempt was made to bring together African-based technological interventions proffered in Sub-Saharan Africa during this period. Across Africa generally, different engineering methods were used to develop several contrivances such as ventilators as well as deploying Artificial Intelligence to facilitate contact-free human-human and human-object interactions. Broadly, these approaches center on two key areas which are efforts to mitigate the spread of the infectious disease, and management of the infected, which are the focus of this present work. Indeed, a comprehensive report of these efforts is essential to appraise the contributions of the home-based researchers and to create an archive for future research and decision making across the African continent, thus necessitating the need for this systematic appraisal.

DESIGN OF A CONCEPTUAL FRAMEWORK FOR CYBERSECURITY CULTURE AMONGST ONLINE BANKING USERS IN NIGERIA

2023-10-17T05:51:20+00:00

This study aims to construct a comprehensive conceptual framework that elucidates the critical human factors influencing cybersecurity culture among online banking users in Nigeria. The research methodology is grounded in a meticulous examination of existing literature in the cybersecurity culture domain, serving as the foundation for this framework. The literature review reveals a conspicuous absence of academic research on cybersecurity culture within Nigeria and underscores the importance of comprehending its unique nuances. Key findings from the literature review highlight the prominence of “cybersecurity awareness,” “cybersecurity policy,” and “cybersecurity education” as influential factors. “Cybersecurity awareness” emerges as the most pivotal factor due to its recurrent emphasis and recognized centrality. “Cybersecurity policy” and “cybersecurity education” secure the second and third positions, respectively, due to their acknowledged significance in cultivating a security-conscious mindset among online banking users. Furthermore, the literature review exposes a research gap concerning the requisite “cybersecurity knowledge” that should permeate organizations and individuals to augment cybersecurity culture. Additionally, it reveals the underexplored influence of “social norms” and “interpersonal trust” in molding cybersecurity culture. This research accentuates the dearth of cybersecurity culture research within Nigeria and underscores the importance of understanding its unique facets. The proposed conceptual framework provides a valuable resource for designing tailored cybersecurity strategies and programs in Nigeria’s online banking sector. It advocates for prioritizing cybersecurity awareness, education, and policy, empowering users with the knowledge and skills needed to safeguard themselves against cyber threats. The model also highlights the relevance of recognizing the role played by social dynamics, interpersonal trust, and social norms in shaping cybersecurity behaviours.

AWARENESS OF CYBERCRIME AMONG ONLINE BANKING USERS IN NIGERIA

2023-09-01T18:23:57+00:00

This study aimed to investigate the awareness of cybercrime among online banking users in Nigeria and provide quantitative data on various aspects related to cybersecurity awareness. A comprehensive survey was conducted among 283 online banking users in Nigeria to gather data. The data were analyzed to identify trends and patterns in cybersecurity awareness among Nigerian online banking users. The study revealed that 82.0% of the respondents were aware of cybercrime, indicating a high level of awareness among Nigerian online banking users. Social media (37.5%) and friends (16.0%) were identified as the primary sources of knowledge about cybercrime. The majority of respondents employed multi-factor authentication methods, such as login + password + biometric, to secure their online banking accounts. However, there was room for improvement in password preferences, as some respondents still used simple passwords. The most used features of online banking were transferring money between accounts (42.4%), checking account balances (26.5%), and paying bills (11.0%). This study contributes new insights to the existing body of knowledge by providing a comprehensive analysis of cybersecurity awareness among Nigerian online banking users. It emphasizes the evolving landscape of cybercrime awareness, the influence of digital platforms in disseminating information, and the importance of targeted awareness campaigns and improved security measures.

AN EXPLORATORY INVESTIGATION INTO THE STATUS OF WATER, SANITATION AND HYGIENE (WASH) OF SCHOOLS IN ENUGU STATE, NIGERIA

2023-10-19T20:52:26+00:00

The status of water, sanitation and hygiene (WASH) facilities was investigated in sixty schools in seven local government areas of Enugu State, Nigeria. A total of sixty schools comprising of twenty-four (24) private schools, twenty (20) government schools and Sixteen (16) mission schools were investigated in this study. Using questionnaire and on-the-spot assessment, WASH facilities in the selected schools were subjected to in-depth scrutiny. The highest number of schools that do not have a water source within the school premises are government schools (10), followed by private schools (7) and then mission schools (2). About seventy-one percent (71%) of the schools investigated rely on self-help water supply sources such as water vendors, rainwater harvesting and private boreholes. Fifty-seven (57) or 95% of the sixty (60) schools of all the schools have toilet facilities ranging from improved pit latrine (10%), flush toilet (31.7%) and pour flush toilet (53.3%). With respect to toilet cleaning, 33%, 17% and 50% of private, government and mission school clean their toilets every day. Fifty-five percent (55%) of all schools always provide handwashing facilities while 13.3% never provide handwashing facilities. Based on school category, the distribution of schools that provide handwashing facilities are as follows: private schools – 54.2%, government schools – 40% and mission schools – 75%. There was a significant correlation (r = 0.85) between availability of toilet facilities and provision of handwashing facilities. There was also a significant correlation (r = 0.555) between the provision of handwashing facilities and the provision of soap.

EDITORIAL

2023-11-01T16:33:57+00:00