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Entropy Generation For Non-Newtonian Fluid With Constant Viscosity 粘性恒定的非牛顿流体的熵生成
African Journal of Mathematics and Statistics Studies Pub Date : 2024-04-03 DOI: 10.52589/ajmss-3fowtmhb
Obi Boniface Inalu
{"title":"Entropy Generation For Non-Newtonian Fluid With Constant Viscosity","authors":"Obi Boniface Inalu","doi":"10.52589/ajmss-3fowtmhb","DOIUrl":"https://doi.org/10.52589/ajmss-3fowtmhb","url":null,"abstract":"In this research, entropy generation for non-Newtonian fluid flow with constant viscosity is considered. The governing nonlinear equations of motion are solved analytically with regular perturbation techniques. Third grade fluid is employed to account for the non-Newtonian influence. The influence of some physical parameters involved in the analysis is studied. Results show that the parameter has the tendency of increasing the velocity of the fluid flow as well as the temperature of the cylindrical pipe. It is observed that as the Brinkman parameter increases, the cylindrical wall temperature is enhanced. Entropy generation number for both heat transfer and fluid friction for various values of and is examined. Results indicate that increase in these parameters increases the temperature of the cylinder, thereby increasing the entropy generation number.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"253 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140746261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Comparative Evaluation of Six Agglomerative Hierarchical Clustering Methods With a Robust Example 以稳健示例比较评估六种聚合分层聚类方法
African Journal of Mathematics and Statistics Studies Pub Date : 2024-04-01 DOI: 10.52589/ajmss-qxph8r1n
Eric U. O., Michael O. O.
{"title":"Comparative Evaluation of Six Agglomerative Hierarchical Clustering Methods With a Robust Example","authors":"Eric U. O., Michael O. O.","doi":"10.52589/ajmss-qxph8r1n","DOIUrl":"https://doi.org/10.52589/ajmss-qxph8r1n","url":null,"abstract":"The agglomerative hierarchical clustering methods are the most popular type of hierarchical clustering used to group objects in clusters based on their similarity. The methods are represented by a bottom-up approach where each object starts in its cluster and pairs of clusters are merged as it moves up the hierarchy. In this paper, we present six agglomerative hierarchical clustering methods namely: the single linkage method, complete linkage method, average linkage method, centroid method, median method, and Ward’s method. We also evaluated how these methods work on a practical basis using a matrix of distance pairs of five points. It was observed that the single linkage method through its dendrogram produced the most similarity measure between x_i and x_j, while Ward’s method produced the highest distance measure between x_i and x_j.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"387 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140778765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Autocovariances and Autocorrelation Properties of Diagonal Vector Autoregressive and Multivariate Autoregressive Distributed Lag Models 对角向量自回归模型和多元自回归分布滞后模型的自变量和自相关特性
African Journal of Mathematics and Statistics Studies Pub Date : 2024-03-13 DOI: 10.52589/ajmss-luf1et0z
Udoh E. D., Usoro A. E.
{"title":"Autocovariances and Autocorrelation Properties of Diagonal Vector Autoregressive and Multivariate Autoregressive Distributed Lag Models","authors":"Udoh E. D., Usoro A. E.","doi":"10.52589/ajmss-luf1et0z","DOIUrl":"https://doi.org/10.52589/ajmss-luf1et0z","url":null,"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.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"46 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140245398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Choice of Maximum Likelihood Estimate among the Lognormal, Weibull and Mixed-Lognormal-Weibull Distributions: An Empirical Examination of Stock Price Returns 在对数正态分布、威布尔分布和混合对数正态-威布尔分布中选择最大似然估计值：股票价格回报率的实证检验
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-12 DOI: 10.52589/ajmss-7kx2rz7r
Chukwudi Anderson Ugomma
{"title":"The Choice of Maximum Likelihood Estimate among the Lognormal, Weibull and Mixed-Lognormal-Weibull Distributions: An Empirical Examination of Stock Price Returns","authors":"Chukwudi Anderson Ugomma","doi":"10.52589/ajmss-7kx2rz7r","DOIUrl":"https://doi.org/10.52589/ajmss-7kx2rz7r","url":null,"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.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"67 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139783725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Choice of Maximum Likelihood Estimate among the Lognormal, Weibull and Mixed-Lognormal-Weibull Distributions: An Empirical Examination of Stock Price Returns 在对数正态分布、威布尔分布和混合对数正态-威布尔分布中选择最大似然估计值：股票价格回报率的实证检验
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-12 DOI: 10.52589/ajmss-7kx2rz7r
Chukwudi Anderson Ugomma
{"title":"The Choice of Maximum Likelihood Estimate among the Lognormal, Weibull and Mixed-Lognormal-Weibull Distributions: An Empirical Examination of Stock Price Returns","authors":"Chukwudi Anderson Ugomma","doi":"10.52589/ajmss-7kx2rz7r","DOIUrl":"https://doi.org/10.52589/ajmss-7kx2rz7r","url":null,"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.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"164 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139843572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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 通过对换群的花环积确定六氯环丙烷化合物全非刚性群的共轭类和特性表
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-12 DOI: 10.52589/ajmss-t9jsevag
Ben O. J., Auta T. J.
{"title":"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","authors":"Ben O. J., Auta T. J.","doi":"10.52589/ajmss-t9jsevag","DOIUrl":"https://doi.org/10.52589/ajmss-t9jsevag","url":null,"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.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"65 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139783736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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 通过对换群的花环积确定六氯环丙烷化合物全非刚性群的共轭类和特性表
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-12 DOI: 10.52589/ajmss-t9jsevag
Ben O. J., Auta T. J.
{"title":"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","authors":"Ben O. J., Auta T. J.","doi":"10.52589/ajmss-t9jsevag","DOIUrl":"https://doi.org/10.52589/ajmss-t9jsevag","url":null,"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.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"131 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139843486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Production Inventory Model with Linear Time Dependent Production Rate, Linear Level Dependent Demand and Demand and Constant Holding Cost 线性随时间变化的生产率、线性随需求变化的需求水平和恒定持有成本的生产库存模型
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-11 DOI: 10.52589/ajmss-8iydeqeu
Atama A. M., Sani B.
{"title":"A Production Inventory Model with Linear Time Dependent Production Rate, Linear Level Dependent Demand and Demand and Constant Holding Cost","authors":"Atama A. M., Sani B.","doi":"10.52589/ajmss-8iydeqeu","DOIUrl":"https://doi.org/10.52589/ajmss-8iydeqeu","url":null,"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","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"104 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139785458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Production Inventory Model with Linear Time Dependent Production Rate, Linear Level Dependent Demand and Demand and Constant Holding Cost 线性随时间变化的生产率、线性随需求变化的需求水平和恒定持有成本的生产库存模型
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-11 DOI: 10.52589/ajmss-8iydeqeu
Atama A. M., Sani B.
{"title":"A Production Inventory Model with Linear Time Dependent Production Rate, Linear Level Dependent Demand and Demand and Constant Holding Cost","authors":"Atama A. M., Sani B.","doi":"10.52589/ajmss-8iydeqeu","DOIUrl":"https://doi.org/10.52589/ajmss-8iydeqeu","url":null,"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","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"45 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139845391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Frechet Reliability for (2+2) Cascade Model 2+2 级联模型的弗雷谢特可靠性
African Journal of Mathematics and Statistics Studies Pub Date : 2024-02-02 DOI: 10.52589/ajmss-fqvgfoiy
Ahmed H. Khaleel
{"title":"The Frechet Reliability for (2+2) Cascade Model","authors":"Ahmed H. Khaleel","doi":"10.52589/ajmss-fqvgfoiy","DOIUrl":"https://doi.org/10.52589/ajmss-fqvgfoiy","url":null,"abstract":"In this paper, a reliability function 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 traced 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 was 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 was presented that least square estimation is the preferred for estimating the function of reliability.","PeriodicalId":251990,"journal":{"name":"African Journal of Mathematics and Statistics Studies","volume":"32 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139868795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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