CURRENT ISSUE   Vol. 5 No. 1 – March 2021

Articles


Multilinear Regression Model to Estimate Mud Weight

Oloro J. O. and Akhihiero T. E.

https://doi.org/10.36263/nijest.2021.01.0229

ABSTRACT
Estimation of mud weight poses a serious challenge to mud industries. In this study, a model was developed to tackle the problem of estimation of mud weight using multilinear regression techniques. The model was developed using data obtained from production records. The data include mud weight, water and other chemicals (materials) for nine different samples. The data were analysed to establish linearity and the data was substituted into the multiple regression to form a matrix with nine unknown regression parameters which was substituted into the regression equation to form the model. T-test and F –test was used to validate the model. Results from the test suggest that the developed model was reliable. The model was used to estimate mud weight for four samples and the results are reliable. The effect of each variable was also considered and results also show that each of the variables affects the mud weight.

Keywords: Regression, Fluid, Mud weight, Caustic soda, Barite

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Assessment of Uncharred Palm Kernel Shell as a Filter Medium in Low Rate Filtration

Jeje J. O. and Oladepo K. T.

https://doi.org/10.36263/nijest.2021.01.0246

ABSTRACT
This study examined the use of uncharred palm kernel shells as a filter medium in low rate filtration as a water treatment alternative. The filter column was made of 150 mm diameter PVC pipe about 1.8 m high. The filter medium (uncharred palm kernel shells) with size range 0.15 – 0.60 mm overlying two layers of graded gravels. The raw water passed through the filter medium and the effluent collected in a metal tank. The effluent was evaluated by monitoring the flow rate, turbidity, filtration rate, bacteriological quality and headloss across the filter bed for a daily six hour run for 14 days. The filter bed was cleaned using the throwing-over method after the filtration rate became appreciably very low at 1.20 l/min-m2. It was found from the results obtained that uncharred palm kernel shells could serve as an effective filter for low rate filtration relative to sand. An average hydraulic loading and filtration rate of 120.35 l/min-m2 and 5.5 l/min-m2 were achieved respectively. The turbidity of the filtered water reduced below 5.5 NTU after the eleventh day and the bacteriological treatment level though excessively high at 65 coliform/100 ml showed reducing tendencies (120/100 ml to 65/100 ml).

Keywords: Filtration, Uncharred palm kernel shells, Headloss, Low rate filtration, Potable water

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Electrical Conductivity of PA6/Graphite and Graphite Nanoplatelets Composites using Two Processing Streams

Umar M., Ofem M. I., Anwar A. S. and Usman M. U.

https://doi.org/10.36263/nijest.2021.01.0251

ABSTRACT
The percolation threshold (PT) of any polymer/particulate carbon composite depends on the processing, the dispersed state of the filler, the matrix used and the morphology attained. Sonication technique was used to make PA6/G and PA6/GNP composites employing in situ polymerisation, after which their electrical conductivity behaviours were investigated. While overhead stirring and horn sonication were used to distribute and disperse the carbon fillers, the composites were made in 2 streams 40/10 and 20/20. The 40/10 stream implies that while dispersing the carbon fillers in PA6 monomer, 40% amplitude of sonication was applied for 10 minutes whereas the 20/20 stream implies 20% amplitude of sonication for 20 minutes. In both streams, the dispersing strain imparted on the monomer/carbon mixture was 400 in magnitude. Purely ohmic electrical conductivity behaviour was attained at 9.75 G wt. % for IG 40/10 system. For composites in the IG 20/20 system, same was attained at 10.00 G wt. %. Electrical conductivity sufficient for electrostatic discharge applications was achieved above 15 G wt. % in the IG 40/10 system. Using the power law percolation theory, percolation threshold was attained at 9.7 G wt. % loading in IG 40/10 system, while same was attained at 7.6 G wt. % loading in IG 20/20 system. For the GNP based systems, percolation threshold occurred at 5.2 GNP wt. % in the INP 40/10 system whereas same occurred at 7.4 GNP wt. % in the IG 20/20 system.

Keywords: Electrical-conductivity, Graphite, Percolation-threshold, Amplitude, Sonication

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Vulnerability Assessment of Components in a Typical Rural Nigerian Power Distribution System

Omoroghomwan A. E., Igbinovia S. O. and Odiase F. O.

https://doi.org/10.36263/nijest.2021.01.0237

ABSTRACT
The major aim of any power system is the continuous provision of safe, quality and reliable electric power to the customers. One of the greatest challenges to meeting up with this goal is the failure of components in the system. In this article, the frequency of outages caused by failure of different components in the distribution system was investigated to ascertain the ones that are more susceptible to failure by comparing their proportions in the entire failure events. The outage data obtained from Irrua Transmission Station comprising Ehor, Ubiaja and Uzebba 33kV feeders were analyzed using Microsoft Excel while the hazard rates were measured using the failure rate index. Findings revealed that 93.77% of all the forced outages in the distribution subsystem in the power sector are caused by the high exposure rate of the bare aluminum conductors used in the construction of the various overhead feeders. Subsequently, the yearly failure rates of aluminum conductors, cross arms, relay, insulators, fuses, electric poles, breakers, transformers, isolators, cables lightning surge arresters were found to be 836.0, 17.5, 17.0, 10.3, 4.3, 2.0, 1.5, 1.3, 1.0, 0.5 and 0.3 respectively in the studied network. A comparison between this study and a related work showed that the rural feeders are more prone to faults as compared to the ones in the urban areas. It was therefore recommended that regular tree trimming along the network corridor should be done. Proper conductor size should be used in every subsequent construction and every segment with undersized conductor should be replaced with the appropriate size. This study will help the power system engineers in the design, construction, maintenance and operation of the distribution power system for optimum and improved system performance.

Keywords: Vulnerability assessment, Power system components, Nigeria power sector, NEMSA, Bathtub curve, Failure rate, NERC

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