| 1 |
Author(s):
T. O. Awodola, B. B. Awe, S. A. Jimoh.
Page No : 1-19
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Vibration of Non-Uniform Bernoulli-Euler Beam Under Moving Distributed Masses Resting on Pasternak Elastic Foundation Subjected to Variable Magnitude
Abstract
This paper investigates the dynamic response of a clamped-clamped non-uniform Bernoulli-Euler beam resting on a Pasternak elastic foundation to variable magnitude moving distributed masses. The predicament is dictated by a partial differential equation of fourth order, which features coefficients that are both variable and singular. The primary aim is to derive an analytical solution for this category of a dynamic problem. To achieve this, we employ the method of Galerkin with a series representation of the Heaviside function to reduce the equation to second-order ordinary differential equations with variable coefficients. We simplify these transformed equations using (i) the Laplace transformation technique in conjunction with convolution theory for solving moving force problems, and (ii) finite element analysis in conjunction with the Newmark method for solving analytically unsolvable moving mass problems due to their harmonic nature. We first solve the moving force problem using the finite element method and compare it against analytical solutions as validation for its accuracy in solving analytically unsolvable moving mass problems. The numerical solution obtained from the finite element method is shown to be comparable favorably against analytical solutions of our moving force problem. Lastly, we calculate displacement response curves for both moving distributed force and mass models at various time t for our dynamical problem presentation purposes.
| 2 |
Author(s):
Uyodhu A. Victor-Edema, Onoriode E. Akehwe.
Page No : 20-32
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Application Of Linear Programming in the Minimization of Transportation Cost in Dangote Cement, Port Harcourt
Abstract
This study delved into the optimization of transportation expenses for Dangote Cement in Port Harcourt, Rivers State. It aligned the quantities of products required by national distributors with the supply available from their depots, employing linear programming techniques to achieve cost minimization. Three sources (depots) - Onne, Rumuodumaya and Trans Amadi as well as six destinations (national distributors) - Aluu, Bori, Elelewon, Omagwa, Oyibo and Rumuola were examined. The secondary data was obtained from a field survey and it contained the unit cost (in Naira) of transporting the products per bag from their various sources to various destinations as at October, 2023. Also, the data obtained from Dangote Cement National Consumer Promotion 2020 (Redemption Centres Detail) contained the list of eleven national distributors in Port Harcourt; however, only six of the national distributors were used in this research. Initial feasible solutions for the secondary data collected were determined through the application of the North-West Corner Method, the Least Cost Method, and the Vogel Approximation Method resulting in values of ₦452,000, ₦380,750, and ₦370,500, respectively. Upon analyzing the outcomes, it was established that the allocation strategy proposed by the Vogel Approximation Method is the most advantageous for optimizing the company's transportation costs. As such, it is recommended to the company as it offers the potential to reduce transportation expenses to a minimum of ₦370,500.
| 3 |
Author(s):
Jelten B. Naphtali, Enoch Suleiman, Hassan Sade .B., Adamu Danbaba.
Page No : 33-49
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On the Commutativity Degree of Finite Groups of Order via Degree Equation
Abstract
Abstract
| 4 |
Author(s):
Ahmed Haroon Khaleel .
Page No : 50-63
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The Frechet Reliability for (2+2) Cascade Model
Abstract
In this paper In this paper, a reliability function was found for one of the cascade models was found, the model consists of two basic components (B_1 and B_2 ) and two spare components (B_3 and B_4 ), and it is sufficient for the model to be in a working state with the presence of two active components and in case of failure of one of the two basic components, it is compensated with one of the two standby components to keep the model running. It was assumed that the strength-stress factors trace the Frechet, the parameters of the Frechet were estimated by three different estimation methods (Moments, Least Squares and Weighted Least Square,), after which the reliability of the model is estimated. Monte Carlo simulations were also conducted to compare the results and find out which estimation methods are the best to estimate the reliability of the model using two statistical criteria: MSE and MAPE, where it presented that least square estimation is the preferred for estimating the function of reliability.
| 5 |
Author(s):
A. Atama Madaki, B. Sani.
Page No : 64-79
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A Production Inventory Model with Linear Time Dependent Production Rate, Linear Level Dependent Demand and Demand and Constant Holding Cost
Abstract
In this paper, a production inventory model with linear time dependent production rate is considered. The market demand is assumed to be linear level dependent while the holding cost is a constant. The model considered a small amount of decay without having any shortage. Production starts with a buffer stock reaching its maximum desired level and then the inventory begins to deplete due to demand and deterioration. The model is formulated using a system of differential equations and typical integral calculus was used to analyze the inventory problems. These differential equations were solved to give the best cycle length T_1^*=0.8273(303 days), Optimal time for maximum inventory t_1^*= 0.7015, Optimal order quantity Q_1^*=38.3404 and total average inventory cost per unit time TC(T_1)* =170.5004. The cost function has been shown to be convex and a numerical example to show the application of the model has been given. A sensitivity analysis is then carried out to see the effects of parameter changes
| 6 |
Author(s):
Chukwudi Anderson Ugomma.
Page No : 80-96
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The Choice of Maximum Likelihood Estimate among the Lognormal, Weibull and Mixed-Lognormal-Weibull Distributions: An Empirical Examination of Stock Price Returns
Abstract
This paper compared the maximum likelihood estimates (MLE) of lognormal, Weibull and Mixed-lognormal-weibull distributions. The data for this study were Coca-cola stock price returns obtained from https://ng.www.investing.com/equities/cocacola-bottle-historical-data and the result with the help of Excel package shows that Weibull distributionhas the minimum Mean Squared Error among the lognormal and Mixed-lognormal-weibull distributions; hence, the maximum likelihood estimate of the Weibull distribution is the choice.
| 7 |
Author(s):
Ben O. Johnson, Auta T. Jonathan.
Page No : 97-103
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Determination of the Conjugacy Classes and Character Table of the Full Non-Rigid Group of Hexachlorocyclopropane Chemical Compound via Wreath Product of Pair of Permutation Groups
Abstract
The use of full non-rigid (f.NRG) molecules group theory to study the internal dynamics of molecular structures of chemical compounds is trending in the research space. In this paper, we use computational method to compute the group elements and group table of the Hexachlorocyclopropane molecular (algebraic) structure and thereafter determine the order and conjugacy classes of the group and finally the corresponding symmetry for each permutation group. We considered the point group of the compound which turns out to be isomorphic to the Wreath Products C3wrC2, where Cn denotes a cyclic group of order n. We found that the group has order 18 and 9 conjugacy classes. Investigating the solubility of the components of Hexachlorocyclopropane chemical compound can be considered for further study.
| 8 |
Author(s):
Michael C. Anyanwu, Emmanuel C. Duru.
Page No : 104-113
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Modeling the use of Trace-Test-Isolate-Treat Strategy for Controlling the Spread of Covid-19
Abstract
During the COVID-19 pandemic that ravaged the entire world between 2019 and 2021, the Trace-Test-Isolate-Treat Strategy was devised as an emergency way of managing the spread of the disease. As the name implies, the Trace-Test-Isolate-Treat Strategy involves identifying those who had contact with an infected person through contact tracing, and subsequent isolation and treatment if confirmed to be infected with the disease. This paper aims to model the transmission dynamics of COVID-19, with the Trace-Test-Isolate-Treat Strategy as a control strategy. To do this, we propose a simple nonlinear system of ordinary differential equations that models COVID-19 dynamics and incorporates the Trace-Test-Isolate-Treat strategy as a way of controlling the spread of the disease. The analysis of the model shows that the disease-free equilibrium is locally asymptotically stable if the reproduction number, R_eff is less than one. Furthermore, the model is shown to possess a unique and stable endemic equilibrium if, R_eff>1. This confirms the global asymptotic stability of the disease-free equilibrium and the absence of backward bifurcation in the model. Numerical plots show the effectiveness of isolation and treatment of infected persons in reducing the spread of the disease.
| 9 |
Author(s):
Emediong Udoh, Anthony Usoro.
Page No : 114-142
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Autocovariances and Autocorrelation Properties of Diagonal Vector Autoregressive and Multivariate Autoregressive Distributed Lag Models
Abstract
The primary aim of this study was to conduct a comparative analysis of the performance of parsimonious models, specifically the Diagonal Vector Autoregressive (VAR) and Multivariate Autoregressive Distributed Lag (MARDL) Models, using their respective Autocovariance and Autocorrelation properties. This comparison was driven by the imposition of restrictions on parameters within the coefficient matrices, specifically limiting them to diagonal elements. To assess the efficacy of these novel multivariate lag models, we utilised data derived from key macroeconomic variables, including Nigeria's Gross Domestic Product (GDP), Crude Oil Petroleum (C/PET), Agriculture (AGRIC), and Telecommunication (TELECOM). The data was subjected to first-order differencing of the logarithm of the series to ensure stationarity. Subsequently, the models were estimated, and autocovariances and autocorrelations of the processes were derived for the analysis. The empirical findings revealed notable patterns, particularly the direct converse autocorrelation observed in both VAR and MARDL models. The negative autocorrelation identified in the macroeconomic variables suggests that periods of economic expansion were succeeded by contractions and vice versa. This implies a complementary relationship between the two models in effectively capturing the dynamics of multivariate lag variables. In conclusion, our study underscores the significance of considering the Diagonal Vector Autoregressive and Multivariate Autoregressive Distributed Lag Models with restricted parameters in the diagonal elements when modelling multivariate lag variables. These findings contribute to a nuanced understanding of the interplay between economic variables and provide valuable insights for researchers and practitioners in the field.
| 10 |
Author(s):
Okunowo B. Olukorede, Taiwo A. Ishola, Olatayo T. Olabisi.
Page No : 143-156
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Modelling the Effect of Police Motivating Factors on Effective Crime Management in Nigeria
Abstract
This study investigates the relationship between police motivating factors' and the crime rate in Nigeria. The fixed effect panel data model with geopolitical zones and states as dummy variables results indicated the significance of motivating factors aside from logistics and insurance with multiple R-squared values of 76.65%. The random effect panel data model showed every motivating factor was significant with multiple R-squared values of 53.81%. Therefore, based on multiple R squared values, the fixed effect panel data model explained the variations in crime rate better—random effect study. Conclusively, police motivating factors have a significant impact on the crime rate in Nigeria.
