Afrika Matematika最新文献_第5页

A comprehensive analysis of transient heat flow around fins 翅片周围瞬态热流的综合分析

IF 0.8

Afrika Matematika Pub Date : 2026-07-11 DOI: 10.1007/s13370-026-01480-4

Ali Raza, Alhussein Ahmed, Raseelo Moitsheki, A. H Kara

{"title":"A comprehensive analysis of transient heat flow around fins","authors":"Ali Raza, Alhussein Ahmed, Raseelo Moitsheki, A. H Kara","doi":"10.1007/s13370-026-01480-4","DOIUrl":"10.1007/s13370-026-01480-4","url":null,"abstract":"<div><p>This study investigates transient heat transfer in longitudinal rectangular fins, where both thermal conductivity and the convective heat transfer coefficient are assumed to vary linearly with temperature. The governing nonlinear partial differential equation (PDE) is analyzed under two distinct boundary conditions: a step change in base temperature and a step change in base heat flux. Lie symmetry methods and conservation laws are used to derive invariant solutions and conserved vectors for various values of the nonlinearity exponent <i>n</i>. The analysis reveals that there are additional symmetries and nontrivial conservation laws for specific cases, notably <span>(n=-1, n=0)</span> and <span>(n=1)</span>, while no conserved vectors are found for <span>(n ge 2)</span>. Closed-form invariant solutions are obtained for the case <span>(n=-1)</span>. To complement the analytical work, a numerical solution is carried out using the Method of Lines (MOL), with finite difference discretization in space, and the transient thermal behavior is visualized through surface and trajectory plots. Furthermore, the modified <span>(left( frac{Z^{prime }}{Z}right) )</span>-expansion method is applied to construct exact traveling wave solutions for the physically relevant case <span>(n=2)</span>, yielding bright, periodic, kink, anti-kink, and rational soliton-type solutions depending on parameter choices. The combined analytical and numerical approaches provide a comprehensive understanding of the nonlinear thermal dynamics in fin systems, offering useful insights for engineering applications involving transient heat dissipation.\u0000</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13370-026-01480-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On JJ-algebras 在JJ-algebras

IF 0.8

Afrika Matematika Pub Date : 2026-07-09 DOI: 10.1007/s13370-026-01479-x

Joemar C. Endam, Joselito O. Jayme

引用次数: 0

AG codes on abelian schemes and quadric fibrations over a curve 曲线上的阿贝尔格式和二次振动的AG码

IF 0.8

Afrika Matematika Pub Date : 2026-07-06 DOI: 10.1007/s13370-026-01475-1

Tohru Nakashima

引用次数: 0

The fractional Hermite–Hadamard type inequalities for uniformly convex functions 一致凸函数的分数阶Hermite-Hadamard型不等式

IF 0.8

Afrika Matematika Pub Date : 2026-07-02 DOI: 10.1007/s13370-026-01477-z

Yamin Sayyari

引用次数: 0

On the convexity of the Berezin range of composition operators and related questions 复合算子Berezin值域的凸性及相关问题

IF 0.8

Afrika Matematika Pub Date : 2026-06-29 DOI: 10.1007/s13370-026-01474-2

Athul Augustine, M. Garayev, P. Shankar

{"title":"On the convexity of the Berezin range of composition operators and related questions","authors":"Athul Augustine, M. Garayev, P. Shankar","doi":"10.1007/s13370-026-01474-2","DOIUrl":"10.1007/s13370-026-01474-2","url":null,"abstract":"<div><p>Let <span>( T )</span> be a bounded linear operator acting on a reproducing kernel Hilbert space (RKHS) <span>( mathcal {H} )</span> over a set <span>( X )</span>. The <i>Berezin range</i> of <span>( T )</span> is defined by </p><div><div><span>$$ textrm{Ber}(T) := { langle T hat{k}_{x}, hat{k}_{x} rangle _{mathcal {H}} : x in X }, $$</span></div></div><p>where <span>( hat{k}_{x} )</span> denotes the normalized reproducing kernel of <span>( mathcal {H} )</span> at <span>( x in X )</span>. In general, the Berezin range need not be convex. In this work, we investigate the convexity properties of the Berezin range for certain composition operators acting on classical functional Hilbert spaces, specifically the Fock space on <span>( mathbb {C} )</span> and the Dirichlet space on the unit disc <span>( mathbb {D} )</span>. We further establish an analogue of the elliptic range theorem for the unitarily equivalent Berezin range associated with operators on two-dimensional reproducing kernel Hilbert spaces. Moreover, we characterize the convexity of the unitarily equivalent Berezin range for a bounded operator <span>( T )</span> on a general RKHS. Finally, we provide a description of the invariant subspaces of the multiple shift operator in terms of the Berezin range of diagonal operators.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380882","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

Exploring Fibonacci-stirling and bivariate Fibonacci-Bell polynomials with visual and numerical realms 探索斐波那契-斯特林和二元斐波那契-贝尔多项式的视觉和数值领域

IF 0.8

Afrika Matematika Pub Date : 2026-06-26 DOI: 10.1007/s13370-026-01472-4

Shahid Ahmad Wani, Uğur Duran, Waseem Ahmad Khan, Cheon Seoung Ryoo, Ketan Kotecha

{"title":"Exploring Fibonacci-stirling and bivariate Fibonacci-Bell polynomials with visual and numerical realms","authors":"Shahid Ahmad Wani, Uğur Duran, Waseem Ahmad Khan, Cheon Seoung Ryoo, Ketan Kotecha","doi":"10.1007/s13370-026-01472-4","DOIUrl":"10.1007/s13370-026-01472-4","url":null,"abstract":"<div><p>In recent years, Fibonacci extensions of diverse special polynomials, such as Fibonacci-Hermite, Fibonacci-Euler, Fibonacci-Bernoulli, and Fibonacci-sigmoid polynomials have been defined, and their many relations and properties have been thoroughly analyzed using the content of golden calculus. In this work, we first define the generating function of the Fibonacci-Stirling polynomials of the second kind and investigate diverse properties and relations. These involve summation formulas, addition formulas, golden derivative property, and golden integral representation for the Fibonacci-Stirling polynomials of the second kind. We then consider the generating function of the bivariate Fibonacci-Bell polynomials and investigate various useful properties and identities. These cover summation formulas, addition formulas, golden derivative properties, golden integral representation, symmetric identity, and implicit summation formulas for the bivariate Fibonacci-Bell polynomials. Moreover, we develop multifarious correlations and formulas, including the Fibonacci-Euler polynomials, the Fibonacci-Bernoulli polynomials, the Fibonacci-Stirling polynomials of the second kind, and the Fibonacci-Bell polynomials. Furthermore, we draw the zeros of the bivariate Fibonacci-Bell polynomials, forming 2D and 3D structures, and provide a table including approximate zeros of the bivariate Fibonacci-Bell polynomials. Lastly, we define the Fibonacci differential operator and then provide some Fibonacci differential operator formulas for the Fibonacci-Stirling polynomials of the second kind and the Fibonacci-Bell polynomials.</p></div>","PeriodicalId":46107,"journal":{"name":"Afrika Matematika","volume":"37 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13370-026-01472-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Generalized class of estimators for finite population mean in stratified random sampling 分层随机抽样有限总体均值估计的广义类

IF 0.8

Afrika Matematika Pub Date : 2026-06-18 DOI: 10.1007/s13370-026-01469-z

Pragati Nigam, Housila P. Singh

引用次数: 0

Existence and optimal controls of non-autonomous impulsive integrodifferential evolution equations with nonlocal conditions 非局部条件下非自治脉冲积分微分演化方程的存在性及最优控制

IF 0.7

Afrika Matematika Pub Date : 2026-06-15 DOI: 10.1007/s13370-026-01471-5

Nafy Ngom, Papa Ali Thiam, Khalil Ezzinbi, Mamadou Abdoul Diop

引用次数: 0

Some results on finite dimensional G-fuzzy normed linear spaces 有限维g -模糊赋范线性空间的一些结果