Nigerian Journal of Technology <h3>Welcome to NIJOTECH Homepage</h3> <p>The <strong><em>Nigerian Journal of Technology</em></strong> (NIJOTECH) is published by University of Nigeria Press Ltd, University of Nigeria, Nsukka. The journal has been publishing technical papers since 1975. The copyright owner of the journal is Faculty of Engineering, University of Nigeria, Nsukka.</p> <p> <span style="font-family: arial,helvetica,sans-serif;"><span style="font-size: large;">p-ISSN:<span lang="EN-GB" style="line-height: 115%;">0331-8443</span> | e-ISSN: 2467-8821 </span></span></p> <p> </p> <p><strong>Quarterly Publications: MARCH, JUNE, SEPTEMBER and DECEMBER</strong></p> <p> </p> University of Nigeria Press Ltd en-US Nigerian Journal of Technology 0331-8443 <p><strong>The contents of the articles are the sole opinion of the author(s) and not of NIJOTECH.</strong></p> <p><strong>NIJOTECH allows open access for distribution of the published articles in any media so long as whole (not part) of articles are distributed.</strong></p> <p>A copyright and statement of originality documents will need to be filled out clearly and signed prior to publication of an accepted article. The Copyright form can be downloaded from&nbsp; while the Statement of Originality is in</p> <p>&nbsp;</p> <p>For articles that were developed from funded research, a clear acknowledgement of such support should be mentioned in the article with relevant references. Authors are expected to provide complete information on the sponsorship and intellectual property rights of the article together with all exceptions.</p> <p>&nbsp;</p> <p><strong>It is forbidden to publish the same research report in more than one journal.</strong></p> OPTO-ELECTRONIC AND ELECTROCHEMICAL EVALUATIONS OF PARTICULATE WO3 AND SnO2 IN ELECTROCODEPOSITED Zn- TiO2 NANOCOMPOSITES COATINGS FOR SENSOR APPLICATION <p><em>This study synthesized, characterized and determined the electronic and optical properties of Zn-TiO<sub>2</sub>, Zn-TiO<sub>2</sub>-WO<sub>3 </sub>and Zn-TiO<sub>2</sub>-SnO<sub>2</sub> nano-composite coatings on low carbon steel. It has also determined the effect of these coatings on the corrosion of mild steel in saline environment. This was with a view to produce an active coating to providing alternative to hazardous chromium coating. Active multi functional nano crystalline coatings of the composites were electrolytically fabricated on low carbon steel from Zinc bath, with its Cation and nanoparticulates of TiO<sub>2</sub>, SnO<sub>2</sub> and WO<sub>3</sub> were uniformly codeposited in the Zn matrix. The nano-powders were characterized with Scanning Electron Microscope/Energy Dispersive Spectrometer (SEM/EDS) analyses for confirmation of the chemical compositions and purity. The electrocodeposition bath compositions were developed with 120 gram per litre of ZnCl<sub>2</sub>, 30 gram per litre of KCl along sides with the nanopowders. Other additives including cetylpridinum chloride, 2- Butyne 1,4diol were added as surfactants and Thiourea was added as stabilizer. The coated specimens were sectioned into parts, some of which were characterized with electrical meters and solar simulator to determine the electrical conductivity and solar response of the coated samples respectively. Samples were also subjected to corrosion experiment in 3.5% NaCl (saline) media to study their corrosion resistance properties in the test media through Potentiodynamic polarization method. The results, the electrical conductivity of the generated nano-composite coatings displayed a better electrical conductivity of 2.45E-01Ω<sup>-1</sup>m<sup>-1</sup> which made it a better sensor material and outstanding corrosion resistance with corrosion rate at 0.10116 mm/year. The study concluded that both matrices with the Nano Particulate WO<sub>3</sub> and SnO<sub>2</sub> can be use as sensor materials but the WO<sub>3 </sub>matrix showed a better electrical conductivity both in the presence and absence of uv light and enhanced corrosion protection under light and dark conditions, thus a better sensor’s material.</em></p> Ayodele Daniyan Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 216 221 10.4314/njt.v42i2.8 INCORPORATING GRAIN DETECTION AND SPEED CONTROL MECHANISMS IN HAMMER MILL OPERATIONS <p><em>The traditional way of achieving different grain particle sizes in hammer mills is by manually changing the screen to the desired size. This manual process is a production procedure that is time-consuming, demanding, and resource-draining. This study incorporated a grain identification and speed control mechanism into a hammer mill machine. The grain detection mechanism is a system that recognizes a grain type through an RGB (Red, Green, Blue) colour sensor. The system has been programmed and trained to vary the speed of a 2hp electric motor with a maximum speed of 2800rpm based on the colour-matching result obtained when the grain is scanned on the colour sensor. The machine was evaluated using performance parameters such as power consumption and grain sieve analysis of milled grains using three crops (yellow corn, white corn, and cowpea). The Three crops were programmed for milling at three motor speeds (2800rpm, 2200rpm, and 1800rpm), and the result is presented. This paper showed that fine, medium and coarse aggregates were obtained for all three-grain types by varying motor speeds, eliminating the need to manually change the screen. The system was responsive to grain identification and speed selection as programmed.</em></p> Adekunle Oyelami Adebayo Oluwole Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 222 229 10.4314/njt.v42i2.9 SYNTHESIS AND CHARACTERIZATION OF MEHTYLAMMONIUM BISMUTH IODIDE VIA SOLVENT ENGINEERING <p><em>Hybrid organic–inorganic halide perovskites (OIHPs) are an emerging class of photovoltaic materials that have gained tremendous attention in the field of optoelectronics. This work aims to investigate the characteristics of bismuth-based halide perovskite via solvent engineering for solar cell application. A bismuth-based organo-inorganic perovskite was synthesized and characterized for solar cell application via solvent engineering using Gamma Butyrolactone (GBL) as the based solvent and enhanced with Methylamine (MA) and acetonitrile (ACN). A solution processing facile method was adopted in the synthesis of the perovskite. The solvent engineering aims to tune its band gap and a remarkable band gap of 1.58eV which is within the range of an ideal band gap (1.5-1.6) required for solar cell application. The XRD micrograph exhibited several narrow sharp peaks which indicated crystallinity formation of the synthesized sample with 86% crystallinity. The FESEM/EDS micrograph indicated nature of the formed crystals and the chemical composition of the sample. A multilayer heptagonal crystal was observed. The TGA result showed that the sample is thermally stable at a temperature of 200<sup>o</sup>C before degradation occurred.</em></p> Bello Abdulkareem Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 230 235 10.4314/njt.v42i2.10 LINEAR PROGRAMMING MODEL FOR SCHEDULING BUS RAPID TRANSIT IN LAGOS STATE, NIGERIA <p><em>The amount of time users have to wait influences their mode of transportation choice. Commuters don’t like to wait in the bus station, especially when the weather is terrible and for the purpose of keeping appointments. Scheduling buses to the various bus terminals will meet the commuter’s needs. The aim of the study is to reduce the waiting time of commuters at bus station and to assign buses to each route. A mathematical model called linear programming (LP) was developed to schedule buses to improve the smooth process of the Bus Rapid Transit (BRT) system. The linear programming model was applied to the Lagos Metropolitan Area Transport Authority (LAMATA) data in Lagos State. The proposed method generated three (3) shifts from 6 – 11am in the morning, 11 – 4pm in the midday and 4 – 9pm in the evening subject to two (2) shifts of fifteen (15) hours to reduce the number of hours buses operate per day and also allocated buses for each route for weekdays with five (5) hours per each shift instead of seven (7) hours buses operated per shift. A properly implemented strategy would significantly decrease passengers' long waits at bus stops, reduce the breakdown of buses, man-hours lost, and allows commuters to meet their various schedule for works, meetings, and other assignments.</em></p> Akinlo Mogbojuri Oludolapo Olanrewaju Ademola Adeyeye Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 236 243 10.4314/njt.v42i2.11 DETERMINATION OF BOND WORK INDEX OF BAGEGA GOLD MINERAL DEPOSIT OF ZAMFARA STATE, NIGERIA <p><em>The study determined the bond work index of Begaga gold mineral deposit of Zamfara State Nigeria using Berry and Bruce modified bond method. Sample of gold mineral was sourced using random sampling method. Reference mineral (Granite) of known weight and work index of 15.13Kwh/ton was ground for thirty minutes at a particular speed and power consumed was determined from the power rating of the ball mill. An identical weight of Bagega gold mineral whose work index was to be determined was ground in the same ball mill under same condition as that of reference mineral. Size analysis of the ball mill under same condition as that of the reference mineral was performed. Size analysis of the ball mill feed and discharge for both ores was carried out and 80% passing particle size of the ball mill feed and discharge for the two ores were estimated mathematically using correlation approach. The work index of the Bagega gold mineral was determined by equating the power consumed in the two indexes of the ore. It was found to be approximately 14.24Kwh/ton which is within the acceptable range of 10 - 15.14Kwh/ton indicated in literatures as standard work index range of gold. This value of the work index means that 14.25Kilowatts hour of energy is required to reduced one tonne of the gold ore from 80% passing particle size of 1117.32µm to 80% passing particle size of 800.00µm, it should serve as the work index of Bagega gold. </em></p> Emmanuel Oji A. D. Omah Y. H. Onymisi Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 244 248 10.4314/njt.v42i2.12 Editorial Chidozie Charles Nnaji Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 166 166 10.4314/njt.v42i2.1 VALORIZATION OF FOOD WASTE FOR BIOGAS PRODUCTION; EFFECT OF CO-ENSILING WITH MAIZE STRAW AT DIFFERENT C/N RATIOS <p><em>Food waste (FW) contribute to emission of greenhouse gases as well as environmental pollution. One way of reducing the impact of FW on the environment is by using it for biofuel production. The yield of biofuel from FW can be improved if the substrate is pretreated. In this study, ensiling was used as a cost effective method of pretreating FW for biomethane production. Co-ensiling of FW and maize straw (MS) was carried out at carbon to nitrogen ratios (C/N) of 20, 25, 30 and 35 for 210 days at ambient temperature. Thereafter, the biomethane potential (BMP) of the silages was determined using an automatic biomethane potential test system. Results showed that ensiling reduced both structural and non-structural carbohydrate components of the silages. BMPs of 385.58, 497.39, 520.53, 551.37, 542.16 and 517.29mL/gVS from the unensiled FW, ensiled FW without MS, co-ensiled FW at C/N ratio of 20, co-ensiled FW at C/N ratio of 25, co-ensiled FW at C/N ratio of 30 and co-ensiled FW at C/N ratio of 35 respectively were obtained. A kinetic evaluation showed that the dual pool model gave a better prediction of the experimental BMP of all substrates than the first-order model and the modified Gompertz model.</em></p> Jerome Undiandeye Silas Kiman Musa Askira Abubakar Habiba Mohammed Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 282 288 10.4314/njt.v42i2.17 ASSESSMENT OF SOLID WASTE MANAGEMENT IN OTA, OGUN STATE, NIGERIA <p><em>The rapid rate of population growth and urbanization has impacted the management of municipal solid wastes (MSW) and is increasingly becoming a major concern in many cities in developing countries. Insufficient area coverage for wastes collection, processing system, and unsuitable disposal all appear to be the causal factors. This paper discussed the current situation of solid waste management in Ota municipality as well as the challenges and associated problems. Structured questionnaires, interviews and on-site observations were used for data generation, and subsequently analyzed using descriptive statistics. Results indicated that 28.6% of the respondents incinerate their wastes, while 27.6% of the respondents dispose theirs to public waste bins. About 11.4% deposit their wastes by the road side, while 6.4% dump their wastes in drainages and water bodies. Most respondents incinerate their wastes which would impact negatively on the ozone layer. Results also indicated that 54.3% of the respondents have their wastes disposed regularly, while 66% do not sort their wastes which make them difficult to manage. The city's single dump site was visited in order to have a better understanding of the existing solid waste management measures in place. Other illegal waste dumps in the town were also visited. In order to address the difficulties of solid waste management in the municipality, it is recommended that the state government engage additional Private Service Provider (PSP) operatives to assist with waste collection and transportation, provide suitable facilities, machinery, and equipment, and launch a public awareness campaign.</em></p> AO David Oreofe Olanrewaju Odagbodo Omobolaji Taofeek Opafola Grace Modupeola Amusan Adekunle Adedayo Badejo Olatunji Sunday Olaniyan Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 289 295 10.4314/njt.v42i2.18 ASSESSMENT OF THE PHYSICO-CHEMICAL QUALITY OF UTURU SECTION OF AKU RIVER IN SOUTHEASTERN NIGERIA <p><em>The physicochemical monitoring of water quality is very key both to aquatic life and public health. To date little is known about the water quality downstream of Aku river, located in Uturu, Isuikwato local government area of Abia state. Therefore the aim of the study is to determine the water quality downstream of Aku river in terms of several physicochemical parameters and heavy metals analysis to ascertain the water quality properties and reveal pollution problems. Samples were collected at 15m, 30m, 45m, 60m, 75m, 90m and 105m interval downstream for both seasons. Results of the study shows that temperature, conductivity, hardness, salinity, Total Dissolve Solid (TDS), Total Suspended Solids (TSS), turbidity, pH, Dissolve Oxygen (DO), chlorine, nitrate, lead, iron, arsenic, copper and zinc, were ranged: 24.19<sup>0</sup>C-26.50<sup>0</sup>C, 165.18-275.46µs/cm, 100.26-139.11mg/L, 520.15-815.24ppt, 380.52-710.08mg/L, 15.12-30.68mg/L, 0.32-1.73NTU, 6.6-7.9, 6.21-11.63mg/L, 1.14-3.30mg/L, 65.01-128.05mg/L, 35.53-58.00mg/L, 0.0002-0.007ppm, 0.02-0.15ppm, 0.002-0.006ppm, 0.44-1.03ppm and 0.1-0.27ppm respectively. The presence of TDS, TSS, turbidity and nitrate above World Health Organization (WHO) tolerance limits, confirmed the presence of contaminants in the water body, and hence not suitable for drinking and thus poses a potential threat to aquatic life.</em></p> Obinna Chinyere Yinka Sanusi Fatai Anafi Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 296 303 10.4314/njt.v42i2.19 MIX DESIGN OPTIMIZATION OF HIGH-PERFORMANCE CONCRETE USING LOCAL MATERIALS <p><em>In this paper, twelve different concrete mixes made from local materials were studied with a view to determining which of the mix designs will produce high-performance concrete. Varied water-cement ratios (w/c) of 0.3, 0.35, and 0.4 were studied with different combinations of particle sizes of coarse aggregates. Twelve concrete mixes were then produced, cast, and cured for 7, 14, 21, 28, 45, and 90 days. Superplasticizer was used to facilitate the workability of the concrete mixes. A slump test was first conducted on the fresh concrete to determine its workability, while compressive, flexural, and tensile strength were determined at the end of each curing age in accordance with relevant standards. The results shows that slump value increased with an increase in w/c ratio, while the concrete with 100% 10 mm particle size coarse aggregate had a minimum slump of 24, 37, and 50 mm at w/c of 0.3, 0.35 and 0.4 respectively, but higher slump values of 70, 76 and 83 mm were obtained with concrete containing larger particle sizes combination i.e. 25% of each of 10, 12, 15 and 19 mm sizes. But strengths reduced with an increase in w/c and aggregate particle sizes. Concrete produced with w/c of 0.3 and 10 mm coarse aggregates had a strength of 52.22N/mm<sup>2</sup> at 28 days, which was about 126% of other strengths obtained from other mixes. Statistical models were then proposed to predict the strength of the best-performed concrete mix. The study concluded that it was possible to produce high-performance concrete using local materials, if the mix is properly optimized.</em></p> Efe Ikponmwosa Kolawole Olonade Abdulgafar Sulaiman Emmanuel Akintunde Numeri Enikanologbon Olusegun Kehinde Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 167 174 10.4314/njt.v42i2.2 FILTER MEDIA ENHANCED ELECTROKINETIC REMEDIATED CRUDE OIL CONTAMINATED SOIL: INVESTIGATION OF ITS ENGINEERING PROPERTIES AND ITS SUITABILITY FOR ROAD CONSTRUCTION <p><em>Research have shown how electrokinetic remediation (EKR) technology attempts to tackle the challenge of soil contamination by crude oil. However, the suitability of the resulting remediated soils for use in road construction have not been well reported. This work investigates the engineering properties of filter media enhanced electrokinetic remediated crude oil contaminated soil (COCS) with a view to ascertain its suitability for use in road construction by comparing the performance of charcoal and active carbon as filter materials. COCS collected at a depth of 1m from the Nigerian Pipeline and Storage Company, Kaduna was remediated by using graphite electrodes to pass 1V DC/cm across EKR setups enhanced by incorporating a 1cm thick charcoal and active carbon separately as filter materials across the setups. Average removal efficiencies of 81.4% and 84.6% were obtained against the 78,600 mg/kg oil content of the COCS from charcoal and active carbon filter media enhancements respectively. This showed that active carbon, with higher removal efficiency, is a better filter medium for COCS than charcoal. The compaction and California bearing ratio (CBR) properties of the COCS also improved with the filter media enhanced EKR. However, the CBR values for the filter media enhanced EKR soils only meet the 20% minimum requirements for Type 2 sub-base course materials specified for light trafficked Nigeria roads. As such, charcoal or active carbon filter media enhanced EKR technology can be adopted for remediating COCS for light trafficked Nigeria road construction in areas not subjected to flooding.</em></p> Kabiru Adebayo George Moses John Sani Engbonye Bashir Haruna Ibrahim Fatima Balarabe Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 175 184 10.4314/njt.v42i2.3 EFFECTS OF SODIUM CARBONATE ADMIXTURE AND MIX DESIGN RATIOS ON THE COMPRESSIVE STRENGTH OF CONCRETE <p><em>This study aimed to investigate the impact of sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>) admixture on the acceleration and long-term compressive strength of ordinary Portland cement (OPC) concrete at different mix ratios. Concrete cube specimens (150 × 150 × 150mm<sup>3 </sup>size) were cast at three different mix ratios (1:1.5:3, 1:2:4, and 1:3:6) with sodium carbonate admixture added in increasing dosage of 0.5% from 0 to 2.0% by weight of OPC. Compressive strength tests were conducted on the cast specimens after curing under water for 7, 28, 56 and 90days. Additionally, tests were done to see how sodium carbonate would accelerate setting times of OPC paste. The results of the tests showed that Na<sub>2</sub>CO<sub>3</sub> decreased the initial and final setting times of cement paste from 96 to 67mins and 543 to 387mins respectively. Compressive strength test results for 1:2:4 and 1:3:6 mix ratios showed an increasing trend up to 1.0% Na<sub>2</sub>CO<sub>3</sub> admixture, after which there was a decrease. Meanwhile, 1:1.5:3 mix ratio showed a decrease in strength from 21.87 N/mm<sup>2</sup> at 0% to 14.90 N/mm<sup>2</sup> at 1.0% Na<sub>2</sub>CO<sub>3</sub> addition, after which the strength increased with Na<sub>2</sub>CO<sub>3</sub> percent addition. These results suggest that sodium carbonate has an accelerating effect on concrete setting time, and may aid its early strength development, but has negative long-term effects on concrete strength with increasing dosage. An optimal percentage of 1% Na<sub>2</sub>CO<sub>3</sub> by weight of OPC is advised for accelerating effects in concrete, based on the results of this study.</em></p> Omolafe Andrew Oluwafemi Omotayo C. Arum C. M. Ikumapayi Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 185 190 10.4314/njt.v42i2.4 EVALUATION OF COMPRESSIVE STRENGTH AND ABRASIVE PROPERTIES OF RICE HUSK ASH – CEMENT COMPRESSED STABILIZED EARTH BRICKS <p><em>Cement, the most utilized building material in developing countries like Nigeria, is rising daily, making it hard for low-income people to acquire a home. This study aimed at producing compressed stabilized earth bricks (CSEBs) from Rice Husk Ash (RHA) and cement. After uncontrolled calcination of rice husk, the RHA oxide compositions were assessed by X-Ray Fluorescence. Design Expert (RSM) designed mix proportions for seventeen earth brick variables. Cement-RHA-Soil was blended with 0-5% cement and 20-25% water. Box Behnken Design (BDD) of Response Surface Methodology (RSM) in Design Expert Version 6 was used to generate seventeen (17) design mix proportions (variables) for the CSEBs. After damp curing for three days, compressed stabilized earth bricks (CSEBs) were evaluated for compressive strength and abrasion at 28, 56, and 108 days. RHA was pozzolanic because its major oxides (SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, and Fe<sub>2</sub>O<sub>3</sub>) yielded 75.27%. CSEB compressive strength improved with age. RCB16- CSEBs with 2.5% RHA+2.5% Cement+21.25% WC - exhibited the best compressive and abrasion strength. Thus, RHA is a good cement replacement in CSEB production for cheaper and sustainable building.</em></p> Adesola Oluwabunmi Olumodeji Folahan Ayodele Kayode Dele Oluborode Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 191 198 10.4314/njt.v42i2.5 INFLUENCE OF COMPACTIVE EFFORT ON THE STRENGTH CHARACTERISTICS OF LIME TREATED LATERITE SOIL MIXED WITH UNTREATED TEXTILE EFFLUENT <p><em>Industrial waste generated is a major contributor of total waste worldwide. The proper mechanism for management of these waste needs to be established, especially in developing countries. Therefore, this paper attempts to evaluate the influence of compactive effort on the strength characteristics of lime treated laterite soil mixed with untreated textile effluent. The study was carried out on the index properties, unconfined compressive strength (UCS) and California bearing ratio (CBR) in accordance with the procedures specified by BS 1377 (2) 1990, 1924 (2) and Nigeria General Specifications. Three compactive efforts namely; British Standard light (BSL), West African Standard (WAS) and British Standard Heavy (BSH) were used for the strength characteristics. The findings of the study showed that an increase in the values of lime-TE results in general increase in the strength tests. An improvement in the UCS for 7, 14 and 28days curing period was recorded at peak values of 1531.91, 2199.29 and 2560.48kN/m<sup>2</sup> for BSL, WAS and BSH at soil-lime-TE of 4% lime/75% TE, 8% lime/75% TE and 8% lime/50% TE respectively. For the CBR (soaked), the peak values were recorded at 49.70, 71.13 and 97.25% for BSL, WAS and BSH at soil-lime-TE of 6% lime/50% TE, 6% lime/50% TE and 8% lime/50% TE respectively. Considering the resistance to loss in strength, the values were also peaked at 71.77, 81.74 and 60.63kN/m<sup>2</sup> at mix ratios of 8% lime/100% TE, 6% lime/75% TE and 8% lime/25% TE respectively. On the bases of these test results, it can be concluded that</em><em> the utilization of untreated Textile Effluent positively increased the strength characteristics of the lime treated soil, reduced environmental pollution and save construction cost.</em></p> Faustina Bayang John Sani Omolara Kevin T. Ijimdiya Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 199 208 10.4314/njt.v42i2.6 DETERMINATION OF REFERENCE SERVICE LIFE FOR REINFORCED CONCRETE MULTISTOREY RESIDENTIAL BUILDINGS: CASE STUDY OF AKURE, NIGERIA <p><em>The Service life of a building is the period from commencement of service to the time just before costly maintenance becomes necessary for continued meeting of minimum performance requirements. Knowledge of service life determines whether to demolish and replace a building or major repairs are required and the absence of information on this has led to many building failures. This research therefore aimed to determine the Reference Service Life (RSL); a parameter required for the evaluation of a building’s Service Life. Twenty reinforced concrete multistorey residential buildings around the Federal University of Technology Akure (Nigeria) were assessed via visual inspection, material testing, and structural analysis. Information obtained from the assessment was used to develop a comprehensive open-ended service life database. Non-destructive tests were conducted on the buildings’ structural elements and the results used to determine the service life of each of the buildings with the aid of Life 365 Software. Weighted factors which depend on the quality characteristics, operational conditions and the environment of the buildings were used as a grading system for the assignment of sub-factors for the adjustment of the Life 365 service life values, leading to a value of 29 years as the Reference Service Life (RSL) for the study area. The result obtained will benefit construction professionals and appropriate regulatory authorities in the study area while the procedure can be adopted for service life assessment in other locations lacking appropriate database.</em></p> Joseph Ohiokalode Ilevbaoje Chinwuba Arum Akindele Omoare Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 209 215 10.4314/njt.v42i2.7 AN APPROACH TO CYBERCRIME ISSUES IN DANDUME LOCAL GOVERNMENT AREA OF KATSINA STATE, NIGERIA <p><em>This study investigated cybercrime issues in Dandume Local Government Area of Katsina State. The study aimed to understand the various types of cybercrimes that the community faces and the resulting impacts, particularly educational and psychological effects on the victims. Additionally, the study discussed the main causes of these crimes, particularly among young people. To achieve these aims, the study collected data from 115 residents of Dandume using a structured questionnaire. The collected data was analyzed using statistical tables. The results showed that cybercrime is prevalent in the Dandume community, with many of the participants reporting that they had experienced one form of cybercrime or the other. The most common types of cybercrime reported by the participants were yahoo attack, social media hijacking, credit card threat, government offer scam, and airtime scam. Furthermore, the study revealed that many of the participants were not aware of the various ways they could protect themselves from cybercrime. Furthermore, the study highlighted the effects of these crimes on the victims and discussed the main causes of cybercrimes among users of internet in the area. The paper made some recommendations for minimizing the challenges of cybercrime in Nigeria. The study underscored the importance of community education and awareness-raising on the dangers of cybercrime and suggests the need for increased efforts to implement security measures to protect residents from cybercriminals.</em></p> Jamilu Garba Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 249 256 10.4314/njt.v42i2.13 LOAD PROFILING OF COMMERCIAL AND RESIDENTIAL BUILDING USING CLUSTERING TECHNIQUE <p><em>Data mining is a promising tool used in processing energy data collected from energy consumers. The knowledge derived from energy data is very pertinent in the formulation of various demand-side management programs. This paper uses clustering techniques to segment the energy consumption patterns of residential and commercial buildings; situated at different geographical locations. The two (2) commonly used clustering techniques: K-Means and Agglomerative Hierarchical Clustering, were employed. The result indicates that the choice of clustering technique for load profiling is highly subjective to the nature of the dataset. Hence, using Davies-Bouldin Index (DB) Index and Silhouette Index (SI) as clustering indicators to select an optimum number of clusters and the best clustering technique. Hierarchical clustering was identified as the most appropriate clustering for the two buildings.</em></p> Abayomi Olawumi Folasade Dahunsi Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 257 263 10.4314/njt.v42i2.14 ADAPTIVE REAL-TIME SPECTRUM SELECTION FRAMEWORK AND HANDOVER DECISION ALGORITHM (RSSF-HDA) FOR HETEROGENEOUS NETWORKS <p><em>Carrier aggregation (CA) is a technology introduced by the Long-Term Evolution-Advanced (LTE-A) system to increase user throughput by combining selected number of component carriers (CCs). Its integration with heterogeneous networks enable the mobile user equipment to take advantage of increased throughput and radio coverage of various access technologies. However, due to the mobility of user equipment, these innovations have increased the likelihood of handoff scenarios, resulting in a high outage probability and low throughput.</em> <em>Handover is a crucial part of mobility management since it enables users to move from one cell to another while maintaining connections.</em> <em>However, no single access technique can provide seamless communication without interruption or delay.</em> <em>As a result, creating a suitable handover decision algorithm is necessary for ensuring high-quality service continuity and dependable user equipment access to the network at all times.</em> <em>An Adaptive Real-Time Spectrum Selection Framework and Handover Decision Algorithm (RSSF-HDA) with optimal resource allocation to the deployed system model is presented in this paper. This effort is geared toward preventing communication failure and improving system performance. It further positions the 4G LTE-A framework for inclusive coexistence with the current 5G New Radio enhanced Mobile Broadband (eMBB) use case scenario. </em> <em>The results of the simulation reveal that this method increases system performance in terms of Cell edge spectral efficiency, and Handover success rate above 10% and 13% respectively when compared to Conventional Handover Decision Algorithm (Conv-HDA) and Multi-Influence Factor Handover Decision Algorithms (MIF-HDA).</em></p> Victor Nkeleme L. I. Oborkhale G. Sani Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 264 273 10.4314/njt.v42i2.15 OPTIMAL DESIGN ANALYSIS OF SUBSTATION GROUND GRID MESH <p><em>Substations are grounded by means of earth-embedded electrodes in order to provide safety during normal or fault conditions. Electric substations are effectively grounded to guarantee the proper operation of electrical devices, minimize the likelihood of flash-over during transient conditions as well as dispel lightning strokes. A structure is termed grounded if it is electrically bonded to earth-embedded metallic frames. The earth-embedded metallic frames provide a conducting pathway of electricity to the earth and it is called a ground grid system. Substation ground grid mesh is comprised of vertical and horizontal conductors as well as vertical rods buried beneath the substation ground. Electric current flow through the human body is hazardous. Therefore, ground grid systems should be designed such that the likely electric body current in an operator or passer-by should not exceed the standard defined limits under any foreseeable harmful circumstances and as well provide protection of equipment. The objective of this study is to determine substation, safe ground grid system parameters as well as the cost-effectiveness of designing substation ground grids by comparing the IEEE Std. 80-2000/2013 and the Finite Element Method (FEM). ETAP 16.0 Power Tool is employed in carrying out this analysis. The substation expected maximum short circuit current is stated. The design analysis using both methods is presented separately and suggestions are made with reference to the most cost effective and safest method for the effective designing of the substation ground grid system.</em></p> Abraham Akhikpemelo Copyright (c) 2023 Nigerian Journal of Technology 2023-07-31 2023-07-31 42 2 274 281 10.4314/njt.v42i2.16