Nigerian Journal of Technological Development (NJTD)
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    127 research outputs found

    Evaluating the Stability and Adequacy of NIGNET for the Definition of Nigerian Geodetic Reference Frame

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    A set of Continuously Operating Reference Stations (CORS) distributed all over Nigeria constitutes the Nigerian GNSS Reference Network referred to as NIGNET. Global Navigation Satellite System (GNSS) is a system that uses satellites for autonomous position determination, and is a critical component of the modern-day geodetic infrastructure and services. Using CORS provide geodetic controls of comparable accuracy and a better alternative to the classical geodetic network. As the NIGNET infrastructure is utilised for different geodetic applications, it has become necessary to evaluate the suitability of the network data for the definition of a geodetic reference frame (GRF). This study utilised the technique of Precise Point Positioning (PPP) in position estimation, and time series analysis for temporal monitoring of the network. The sufficiency and adequacy of the NIGNET data archive was also evaluated against that of an International GNSS Service (IGS) Station. The temporal stability of the station coordinates measured in terms of standard deviations varied between 10 mm and 22 mm. This analysis suggests a relative stability required for Tiers 1 and 2 CORS in line with the IGS standards. Based on this reported stability, it is concluded that NIGNET is fit for purpose in defining the Nigerian Geodetic Reference Frame. However, despite the good data quality observed, the adequacy of the network has been compromised by infrastructural failures and lack of continuity in data transmission. Accordingly, it is recommended that both practical and policy measures required to ensure the realisation of the goal of the network should be implemented

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    Effects of Temperature and Steeping Time on the Proximate Compositions and Selected Physical Properties of Soybean Flour

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    A study to investigate the effect of temperature (80, 85, 90, 95, and 100oC)  and steeping time (12, 15, 18, 21, and 24 hours) on the proximate composition (ash, crude fibre, fat , protein, and carbohydrate) values (%) and physical properties (bulk density, packed density (g/ml), angle of repose (degrees), and particle size (µm)) on soybean flour was conducted. Response surface Methodology (RSM) was used for the work. Central Composite Design in Design Expert (version 6.0, 2002, Minneapolis, United States) computer software package was used to design the experiment. Analysis was also done and all results were presented with a three dimensional plot. The results showed that the moisture content of the soybeans flour ranged from 3.26 – 7.35, 3.40 – 4.50 for ash, 3.15 – 4.82 for crude fibre, 31.32 – 35.21 for protein, 19.37 – 22.65 for fat, and 29.66 – 35.19% for carbohydrate. Angle of repose for soybeans flour samples ranged from 33.15 – 38.16o, bulk density varied between   0.30-0.36, packed density varied between 0.52 – 0.57g/ml and   particle size distribution varied between 0.44 – .98µm for the different samples. It was observed that longer steeping time and drying temperature resulted to an increase in the protein content and decrease in crude fibre content. Conversely shorter steeping time and lower drying temperature resulted in an increase in the fat content. A nine-point hedonic scale on sensory and acceptability tests showed that sample soaked for 24 hours and dried at 90oC was most preferred in taste and overall acceptability

    The Development and Performance Evaluation of Solar Photovoltaic Module’s Surface-to-Rear Temperature Controlled Valve for Cooling Application

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    This study investigated the effectiveness of the developed solar photovoltaic (PV) module's surface-to-rear temperature-controlled solenoid valves for PV module cooling application. The cooling fluid is regulated by energizing normally closed (NC) solenoid valve with control parameters as modules rear and surface temperatures. ATmega32 microcontroller was utilized as central processing unit with two (2) LM35 as input sensors and solenoid valve as an output device. Each of 2-LM35 temperature sensors were dedicated to measure module's rear and surface temperatures respectively. The measured temperature values were coded as controlled parameters for regulating cooling fluid discharge by energizing a NC solenoid valve. The system was observed to discharge cooling fluid by energizing the solenoid valve under module's surface and rear temperature difference of less than or equal to 1.50C (Ts-Tr≤1.50C). The module's mean surface temperatures of 49.310C and 54.920C were recorded for temperature-controlled PV cooling applications and a standard solar photovoltaic/thermal (PV/T) system. The maximum recorded surface temperatures for temperature-controlled PV cooling and a standard PV/T systems were 54.00C and 57.60C respectively. The mean absorber temperatures of 45.510C and 40.870C were respectively recorded for temperature-controlled PV cooling and standard PV/T. The maximum absorber temperature recorded for temperature-controlled PV cooling and standard PV/T were 48.300C and 41.630C respectively. The solar cells temperature is reduced by 5.38% through solenoid valve temperature controlled solar module cooling application

    The Continuous Sorption of Chromium Ions from Simulated Effluents using Citric Acid Modified Sweet Potato Peels

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    Adsorptive removal of chromium ion in aqueous medium using activated sweet potato peel (SPP) was studied in a laboratory-scale fixed bed column. Specifically, the effect of process parameters such as bed depth, flowrate and chromium ion concentration in aqueous solution, on the adsorption efficiency of the acid modified sweet potato peel was examined. Column adsorption analysis showed that at the flow rate of 0.5 cm3/min, bed height of 6 cm and column influent concentration of 30 mg/dm3, the optimum chromium (VI) ion removal of 87.5% was attained with the equilibrium adsorption capacity of 2.4548 mg/g. Continuous adsorption models such as Yoon-Nelson, Adam-Bohart and the Bed-Depth Service Time (BDST) model, were used to analyse the experimental data and based on correlation coefficient, BDST model best aligned with the obtained experimental data with  correlation coefficient, R2, value of 96.43%. The bed capacity, No, and the rate constant, Ka, were calculated as 4.259 mg/dm3 and 0.01045 L/mgmin respectively at optimum column conditions. Results confirmed that acid modified SPP can be used to remove or reduce concentrations of Cr (VI) ions to allowable limits before disposal into water bodies. &nbsp

    Computational Schemes in the Design of Novel Materials for Energy Savings

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    Abstract- the current demand for lightweight energy efficient materials in the industry to help in addressing the current challenges faced in reducing green house gas emissions is one of the motivations behind innovative material design. This paper has tried to review in particular the importance of the hierarchical multiscale modelling strategy in the design of novel lightweight materials. It also highlights on one of the hierarchical multiscale modelling methodologies from ab-initio level to macro level in predicting macroscopic material behaviour and the impact this simulation strategy will have on the development of innovative materials. It highlights on the limitations of this modelling strategy such as: the unreasonable computational time associated with the relaxation of polymeric chains or entanglements as well as scale bridging approaches between low level and high level models which are areas of current research interest. &nbsp

    Internal Microclimate: Cumulative Exergy Consumption in a Sandcrete and a Burnt Brick-Walled Structure

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    Current practices of planning and designing of buildings in Nigeria do not consider the thermal comfort, the building energy and exergy demand. There is a need for better understanding of exergy analysis to improve the quality match between building energy demand and supply. The aim of this study is to estimate the exergy consumption value for a hollow sandcrete and a burnt brick-walled structure in a tropical sub-region. The properties of the building were assessed, eQuest software was used to estimate the energy demand of the respective buildings and the exergy analysis was conducted using the exergetic factor of electricity. The cumulative exergy consumptions of the existing sandcrete-walled building, the modelled sandcrete and the burnt brick-walled building were found to be 246,074.4 MJ/year, 128,646 MJ/year, and 128,595.6 MJ/year respectively. The modelled sandcrete-walled building, as well as the burnt brick-walled building, were found to be 48 % more energy efficient than the existing building as a result of improving the airtightness of the building, reducing the solar heat gain, and utilizing extremely efficient systems. However, the exergy analysis suggested that the hollow burnt brick-walled building perform better than the hollow sandcrete-walled building

    Optimal Reconfiguration of Radial Distribution Networks using Improved Genetic Algorithm

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    Reconfiguration of an electrical power radial distribution network is aimed at finding a radial operating structure that minimizes the system active power loss, enhancing the system voltage profile via reducing the active power losses whilst satisfying operating constraints is one of the most important measures of improving the operational performance of a distribution system. In this paper, an efficient approach to solving the problem of reconfiguration considering active power loss, total voltage deviation for a typical distribution network. The method developed is based on improved genetic algorithm to determine the optimal location of tie and sectionalizing switches, with a view to yield an optimal performance for the network. The reconfiguration model was implemented using MATLAB R2016a simulation environment. The effectiveness and validity of the proposed model was tested on a 16, 33 and 69 IEEE-Bus standard systems for distribution network. The results show that with a reduction of 8.86%, 31.15% and 53.53% in active power loss as compared to the initial configuration, whilst a total voltage deviation of 0.0284p.u., 0.0622p.u and 0.0517p.u for 16, 33 and 69 IEEE Bus respectively

    Characterization and Analysis of Propagation Time Delay Range within NigComSat-1R Footprints

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    NigComSat-1R could be part of Networked Control Systems (NCSs) to link plants, controllers, sensors and actuators which may be distributed within the satellite footprints. Associated with NCSs is location-dependent time delay which can drastically reduce system Quality of Performance (QoP), or in the worst case lead to system instability. To ameliorate these effects, the network delay should be taken into consideration at design stage. In order to achieve this, the ranges of propagation time delay incurred within a particular footprint or between two footprints of NigComSat-1R are modelled, simulated, characterized and analyzed. It was observed that the minimum and maximum possible time delays between the boundary of NigComSat-1R footprints and the satellite are 0.1193 sec and 0.141 sec respectively. Also, the minimum possible propagation time delay between any two footprints is that between C-band ECOWAS 1 beam and itself with value of 0.2386 sec while the maximum possible propagation time delay between any two footprints is that between L-band Navigation payload L1 beam and itself or L-band Navigation payload L5 beam and itself with value of 0.2832 sec

    Land Use-Land Cover Effects on Surface Flowing Water Quality: A Statistical Approach

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    The drainage basin surrounding River Kaduna within the middle stretch is known to have numerous land uses and land covers. Several researchers have investigated the water quality of the river with respect to season and surrounding geology. However, none or little on the water quality of the river have been investigated with respect to land use and land cover (LULC). Hence, this paper examined the water quality of the middle stretch of the river in relation to the different land uses and land covers present using statistical techniques. This was achieved by monthly analyzing 10 physicochemical parameters from water samples collected in 15 sampling stations for a period of 12 calendar months using standard methods. The physicochemical parameters considered include; turbidity, total dissolved solids, pH, chloride ion and electrical conductivity. Others include dissolved oxygen, 5-days biochemical oxygen demand, chemical oxygen demand, total nitrogen and total phosphorus. The different LULC of the watershed obtained via ArcGIS 10.5 were agricultural, vegetation, built-up, industrial, water body and bare surface. Spearman’s correlation analysis between laboratory results and the different LULCs determined via SPSS version 20 revealed that Built-up, industrial, and agricultural land uses contributes significantly to the impairment of River Kaduna water quality as the correlation coefficients between these LULCs and water quality deterioration ranged from 0.0281 to 0.6901. Nevertheless, a significant negative correlation (-0.1482 to -0.5490) exist between vegetation (forest coverage) and water quality deterioration, suggesting that forest cover can mitigate the deterioration of water quality to a certain degree


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