Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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State Estimation of the Nigerian 330kv Transmission Network using the Weighted Least Square Optimization Technique
Get PDFThe state of an electrical power system is the vector of voltage magnitudes and voltage angles at each bus across the entire power system network. The estimates of state variables are very important for online monitoring and control, which are valuable assets in power system operations. The state estimator algorithm is a computational mathematical implementation of a state space technique to process erroneous power system measurements into an estimate of the true power system state vector. It is established, through rigorous research that measurement data obtained from supervisory control and data acquistory systems or Phasor measurement unit are not fit for direct system analysis as they contain errors large enough to give a misrepresentation of the system behavior. To address the issue of erroneous data measurements, this work uses the optimized weighted least square technique to estimate the true state of the power system network. This analysis is achieved by setting up mathematical models of the system network and applying the Weighted Least Square estimation technique to different weights depending on type of measurement. A quantitative and qualitative problem of system observability and error detection in measurement is discussed in this paper. The observability and error quantification process is carried out on the IEEE 14 and the Nigerian transmission grid network through the segmentation of observable islands within the network. This work generates important state results using the MATLAB computational software and run state estimate simulations using the PSAT framework. Using the estimation technique in this work the Nigerian network state space estimation results revealed errors embedded in measurement data with a significant deviation of 1.14 of maximum voltage error in comparison with state estimate result and 16% deviation mean of voltage estimation error in comparison with raw measurement data. The deviation between the raw measurement data and the state estimation results depicts that analysis of power networks without applying that state estimation algorithm may give a misinterpretation of the state variables.
 
Effect of Shea Nutshell Ash on the Mechanical Properties of Cast Al6061
Get PDFAluminium Matrix Composites (AMCs) has attracted much interest in aerospace, defence and automotive applications due to its high strength to weight ratio. However, the manufacturing technique, nature and combination of the matrix and reinforcements play a vital role in the success of AMCs. In this study, the mechanical properties of Aluminium metal matrix composites (AMMCs) reinforced with shea nutshell ash (SSA) was investigated. Different mix ratio constituting 0%, 5%, and 10% of SSA were used as reinforcement, with the matrix being Al6061 to compound different samples. The metal matrix composites were produced by stir casting technique. Mechanical properties such as Hardness, Tensile, Impact and Microstructure examination of the developed composites were evaluated. The results showed that with increasing % of SSA, the hardness, and impact energy of the composite increased for both 5 and 10%. However, with increasing SSA the tensile strength decreased slightly for both 5 and 10% SSA. The hardness and the impact energy increased by 166.74% and 76.38% respectively as the wt% of SSA varied from 0-10tw%. On the other hand, the tensile test showed a decrease from 115.67 N/mm2 to 94.52 N/mm2 as the % of SSA increase from 0-10%; which translates to 18.29% reduction in tensile strength. SSA however promises to be a good reinforcement material for hybrid aluminium matrix composites when the properties desired are hardness and impact energy
Effect of Stress and Load Distribution Analysis on an Isotropic Rectangular Plate
Get PDFStructural failure is discovered to be attributed to the inability of the designer to determine the structural load (critical load) that causes it. The aim of this study is to develop a mathematical model for calculation of the critical lateral imposed load of the plate before deflection reaches the maximum specified limit and its corresponding critical lateral imposed load before plate reaches an elastic yield point . Total potential energy equation of a thick plate was formulated from the static elastic theory of the plate. Direct variation method of analysis was adopted by minimizing the total potential energy obtained to determine the expression for the deflection and shear deformation. By solving the formulated expression, the effect of stress and load distribution analysis of a mild steel rectangular plate with one edge clamped, free at the other and the other opposite edge simply supported (CSFS) are analyzed and discussed. From the established equation, a new model for determination of the critical lateral imposed load of the plate is developed. The result showed that: (i) as the specified thickness of the plate increases, the value of critical lateral imposed load increase (ii) the critical lateral imposed load decrease as the plates span increases. iii) the critical lateral imposed load increase as the plate thickness increases. (iv) increase in the value of the allowable deflection value required for the analysis of the plate reduces the chances of failure of a structural member. It is concluded that the values of critical lateral load obtained by this theory achieve accepted vertical shear stress to the thickness of plate variation and satisfied the transverse flexibility of the condition of the plate while predicting the flexural characteristics for an isotropic rectangular CSFS plate. Numerical comparison was conducted to verify and demonstrate the efficiency of the present theory. The results obtained are in good agreement with those in the literature. This approach is recommended to the practicing engineers as it overcomes the challenges of the conventional practice in the structural analysis/design which involves checking of deflection and shear; the process which is proved unreliable.
 
Production, Proximate Composition and Sensory Evaluation of Cereal- Legume Based Infant Food
Get PDFIn this study, a cereal-legume based infant food was formulated from millet, malted millet, cowpea, soybeans, and groundnut. The grains used were blended into four infant formulations of different ratios namely: Formulation 1 (70% millet + 30% soybean), Formulation 2 (65% millet 4- 30% soybean + 5% malt), Formulation 3 (70% millet + 20% cowpea + 10% groundnut) and Formulation 4 (65% millet 4- 20% cowpea + 10% groundnut + 5% malt). Standard methods of analysis were used to determine the moisture content, crude fat, crude protein, ash, pH, titrable acidity (TA), total sugar and bulk density contents for the different formulations; whereas the carbohydrate was computed by difference. Each of the samples from the formulations produced was cleaned, toasted, and milled together. The infant formulations were given to 120 mothers residing within Lake Chad Research Institute, Maiduguri and Usmanti area, which is close to Lake Chad Research Institute, Maiduguri. The prepared infant formulations were made into slurry with boiled water and given to the mothers in order to serve their children when slightly cooled. A 9-point hedonic scale was used in the sensory evaluation of the products. Results obtained showed that the moisture content ranged from 4.4 to 6.5%, ash from 1.5 to 1.9%, protein from 13.6 to 22.1%, carbohydrate from 68.6 to 75.5% and fat from 2.3 to 4.9%; whereas the pH and TA values ranged from 5.5 to 5.6, and 0.68 to 0.74, respectively, while the total brix sugar value ranged from 14.2 to 29.8. The results for sensory evaluation indicated that the cereal-legume based formulations were generally accepted by the mothers for their babies in all the parameters determined. The study indicated that Formulations 3 and 4 had the highest scores for overall acceptability.
 
Sensitivities of some Reference Evapotranspiration Models to the Key Climatic Variables in Northeastern Nigeria
Get PDFReference evapotranspiration (ETo) models are fundamental tools in decision-making in agricultural water management. They have potential spacio-temporal variations due to climatic variability that challenges their individual reliability in decision-making. The sensitivities of five ETo models were examined using the factor perturbation simulation approach (FPSA). The examined models were Penman-Monteith (PM), Hargreaves-Samanni (HS), Blaney-Criddle (BC), Jensen-Haise (JH) and Thornthwaite (TW) to alteration of climatic variables (wind speed (U2), maximum and minimum air temperatures (Tmax and Tmin), vapor pressure deficit (VPD), and Solar radiation (Rn). The study utilized ten years meteorological data obtained from Nigerian Meteorological Agency (NIMET) offices in Maiduguri between (2002-2011) for Borno State, Potiskum between (2005-2014) for Yobe State and from the Upper Benue River Basin Development Authority, Yola (UBRBDAY) between (2005-2014) for Adamawa, Taraba, Gombe, and Bauchi states respectively. Thus covering the entire northeastern region of Nigeria. The region was fractionalized in to three zones namely Borno State (zone A), Yobe State (zone B) and Adamawa, Taraba, Gombe, and Bauchi States (zone C). The results from zones A and B showed some distinctive similarities. Additionally, Blaney-Criddle, Hargreaves-Samanni and Jensen-Haise models outperformed Thorntwaite model, signifying that Thornwaite model is not suitable for application in this region. On an annual average, PM model was most sensitive to U2 and least sensitive to Tmean. BC model was highly sensitive to n/N with sensitivity coefficient (S.C.) of 3.640 in Borno and 3.611 in Yobe, and it was least sensitive to RH. The temperature difference (Tmax-Tmin) was found to have affected HS more than Ra. The Thorntwaite model was most sensitive to solar radiation. Similarly, it was observed that U greatly influenced the performances of the studied ETo models. For accurate and reliable output from any ETo model, emphases need to be placed on accurate measurement, documentation and systematic handling of the climatic variables and calibration.
 
New refined shear deformation theory effect on non-linear analysis of a thick plate using energy method
Get PDFThis study presents the application of a new refined plate theory in the bending analysis of a thick rectangular plate carrying a uniformly distributed load using the direct energy method. The new refined plate theory which is a combination of trigonometric shear deformation theory and fourth order polynomial displacement function was used to formulate the governing differential equation by employing the principle of elasticity. The total potential energy equation of a thick plate was formulated from the constitutive relations thereafter the three general governing differential equations for the determination of the deflection and shear deformations rotation along the direction of x and y coordinates were obtained. The coefficient of deflection and shear deformation were derived by subjecting the energy equation obtained to direct variation thereafter the actual deflection, in-plane displacement, normal and shear stresses, moment and stress resultants of the rectangular thick plate were determined by substituting the derived coefficient of coefficient of deflection and shear deformation into the displacement, shear force, moment and stresses deduced. The particular plate boundary condition to be anlysed is free support at the third edge and the other three edges simply supported (SSFS). The result shows that thick plate is the one whose span-depth ratio value is 4 up to 25. The results obtained from this work was compared with those obtained from other refined plate theories with the same support condition and obtained showed good agreement with those in the literature
Waste to wealth in building materials development: a review of plastic waste in concrete
Get PDFRecently, there has been a growing interest in the use of post-consumer plastics in the production of concrete. Consequently, a large number of studies reporting the behaviour of concrete containing waste and recycled plastics have been published. These studies have great potential for improving the inherent weakness of concrete, reduction of pressure induced on the environment and creation of employment opportunities for economic development. This paper presents a review of journal publications on the effects of waste and recycled plastic materials on some fresh and hardened properties of concrete. The effects of waste plastic materials on slump, density, compressive strength, tensile/flexural strength and permeability are discussed. It was concluded that Post-consumer plastics can be successfully and effectively utilized to replace conventional concrete. This presents a strong potential for the production of sustainable concrete as well as meeting the goals of sustainable development requiring a waste to resource approach. The study suggests public education and awareness on the prospects of using waste plastic in concrete for economic empowerment among the population
AC-DC Solid-State Conversion and Power Factor Correction using Thyristor-Based Static Var Compensator
Get PDFThis paper presents AC-DC solid states converters with thyristor-based static Var compensator in power factor correction. There is need for solid-state ac–dc converters to improve power quality in terms of power factor correction, reduce total harmonic distortion at input ac mains and precisely regulate dc output. AC-DC converters operating in continuous-conduction mode have become popular because of reduced electromagnetic interference levels resulting from their utilization. The method employs the principle of interleaved converters, as it can be extended to a generic number of legs per winding of the autotransformers and high-power levels. The practical analysis of the converter is then plotted using a Simulink model of Matlab while a comparison of power factor and efficiency with relative to the load is drawn with Steady-State and Dynamic Performance of the Static Var Compensator (SVC). An experimental prototype load varied between 400W to 1 KW is implemented to validate the work. The results obtained indicates that when the output loads were 53KW, 135KW, 270KW, 470KW and 900KW, the efficiency were 55%, 70%, 80%, 90% and 97% respectively. These results confirmed that there was improvement in the power factor and efficiency with increase in the load
Study on the Use of Banana and Pineapple Peel Waste as Biofertilizers: Enhancing soil fertility, Promoting Sustainable Agriculture and Environmental Sanitation
Get PDFIndiscriminate agricultural waste disposal especially fruits peels can cause environmental pollution with increased public health risk. This study deals with managing banana and pineapple peel waste as organic fertilizers towards promoting sustainable environmental sanitation and agriculture production. Waste of banana and pineapple peels were separately collected in households, dumpsites and markets, the collected fruits peels were cleaned, sun dried for 33 days and grounded into powdered form. Three different formulations of organic fertilizers were made from the sun dried and finely grounded fruit peels of banana and pineapple, namely; formulation A containing 100g of banana peels powder; formulation B containing 100g of pineapple peels powder and formulation C containing 100g of a mixture of banana and pineapple peels powder. Four different containers were used to collect 10kg of soil each, three of which were treated with the three formulations and named sample A, B, C and an additional sample D which is control. After 30 days of treating the soil with the different formulations. The result of laboratory soil analysis showed that; Sample A contains 14% Nitrogen, 37% Phosphorus, 7% Potassium, 40% Calcium and 2% Magnesium. Sample B contains 11% Nitrogen, 39% Phosphorus, 8% Potassium, 39% Calcium and % Magnesium. Sample C contains 17% Nitrogen, 35% Phosphorus, 4% Potassium, 43% Calcium and 1% Magnesium. Sample D (Controlled Soil Sample) contains 1% Nitrogen, 17% Phosphorus, 4% Potassium, 45% Calcium and 33% Magnesium. It was revealed that the fruit peel powder formulations can increase the soil fertility which serves as alternative replacement for chemical fertilizers towards sustainable agriculture and the environment. It is recommended that the farmers and general public should make beneficial use of fruits waste as organic fertilizers and not to be discarded indiscriminately.
 
Rainfall-Runoff Modeling for Challawa and Jakara Catchment Areas of Kano City, Nigeria.
Get PDFFor the past decade, the magnitude and frequency of rainfall that resulted into flooding of Kano city have been relatively high and there is need to manage the flood in order to safe life and properties. This research aimed at generating Challawa and Jakara catchment areas runoff for hydrological applications. The two catchments were first delineated and their basic physical properties were extracted from processed 30 m x 30 m Digital Elevation Models (DEMs) of the respective watershed. Basin models of the watersheds were imported from ArcGIS 10.7 to Hydrologic Engineering Center – Hydrologic Modelling System (HEC-HMS) environment, the meteorological models were developed in HEC-HMS with rainfall data and control specifications assigned which defined the period and time step of the simulation run. SCS-Curve Number, Unit Hydrograph and Muskingum methods were used for estimation of loss, runoff and flow routing respectively. The rainfall-runoff simulations were carried out for 31 years of maximum daily rainfall record (1988 – 2018). The simulated flow rate obtained can be used for further hydrological analysis such as flood frequency analysis and in design of safe and economical drainage and flood control facilities or in maintenance of culverts, sewers, bridges and roads for Jakara and Challawa catchment areas. It is recommended that; the catchment areas be gauged while further research should be conducted on the quality of the simulated flow obtained