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Acta et Commentationes Universitatis Tartuensis de Mathematica最新文献

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Natural vibrations of circular nanoarches of piecewise constant thickness 片状恒定厚度圆形纳米缝隙的自然振动
IF 0.3
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-08-07 DOI: 10.12697/acutm.2023.27.20
Shahid Mubasshar, J. Lellep
{"title":"Natural vibrations of circular nanoarches of piecewise constant thickness","authors":"Shahid Mubasshar, J. Lellep","doi":"10.12697/acutm.2023.27.20","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.20","url":null,"abstract":"The free vibrations of elastic circular arches made of a nano-material are considered. A method of determination of eigenfrequencies of nanoarches weakened with stable cracks is developed making use of the concept of the massless spring and Eringen's nonlocal theory of elasticity. The aim of the paper is to evaluate the sensitivity of eigenfrequencies on the geometrical and physical parameters of the nanoarch.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"61 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139351453","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
PH approximation of two-barrier ruin probability for Lévy risk having two-sided PH jumps 具有双边PH跳跃的lsamvy风险的双障碍破产概率的PH近似
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.10
Kalev Pärna, Mohammad Jamsher Ali
{"title":"PH approximation of two-barrier ruin probability for Lévy risk having two-sided PH jumps","authors":"Kalev Pärna, Mohammad Jamsher Ali","doi":"10.12697/acutm.2023.27.10","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.10","url":null,"abstract":"In this paper, we study a Lévy risk process consisting of Brownian component together with premiums and claims that are phase-type with many phases. Our aim is to approximate the probability of ruin without touching an upper barrier a. In line with this, the study demonstrates that the described Lévy risk process can essentially be replaced with a simpler risk process in which both premiums and claims are phase-type with just few phases.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135896110","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
(ψ, ϕ)-Wardowski contraction for three maps in Gb-metric spaces Gb-metric空间中三个映射的(ψ， φ)-Wardowski收缩
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.06
Sejal Puvar, Rajendra G. Vyas
{"title":"(ψ, ϕ)-Wardowski contraction for three maps in Gb-metric spaces","authors":"Sejal Puvar, Rajendra G. Vyas","doi":"10.12697/acutm.2023.27.06","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.06","url":null,"abstract":"Introducing (ψ, ϕ) − Gb-Wardowski contraction for three maps, a common fixed point result is obtained for complete Gb-metric spaces. An application related to discontinuous activation function in neural network is also established.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135894866","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
Two types of the second Hankel determinant for the class U and the general class S 两种类型的第二汉克尔行列式为类U和一般类S
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.05
Milutin Obradović, Nikola Tuneski
{"title":"Two types of the second Hankel determinant for the class U and the general class S","authors":"Milutin Obradović, Nikola Tuneski","doi":"10.12697/acutm.2023.27.05","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.05","url":null,"abstract":"In this paper we determine the upper bounds of the Hankel determinants of special type H2(3)(f) and H2(4)(f) for the general class of univalent functions and for the class U.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135894862","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
Further remarks on permissible covariance structures for simultaneous retention of BLUEs in linear models 关于线性模型中同时保留蓝调的允许协方差结构的进一步说明
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.09
Simo Puntanen, Stephen Haslett, Jarkko Isotalo, Augustyn Markiewicz
{"title":"Further remarks on permissible covariance structures for simultaneous retention of BLUEs in linear models","authors":"Simo Puntanen, Stephen Haslett, Jarkko Isotalo, Augustyn Markiewicz","doi":"10.12697/acutm.2023.27.09","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.09","url":null,"abstract":"We consider the partitioned linear model M12(V0) = { y, X1β1 + X2 β2, V0 } and the corresponding small model M1(V0) = { y, X1β1 , V0 } . We define the set V1/12 of nonnegative definite matrices V such that every representation of the best linear unbiased estimator, BLUE, of μ1 = X1β1 under M12(V0) remains BLUE under M12(V) . Correspondingly, we can characterize the set V1 of matrices V such that every BLUE of μ1 = X1β1 under M1(V0) remains BLUE under M1(V). In this paper we focus on the mutual relations between the sets V1 and V1/12 .","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135896103","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
On the identities of Ramanujan – a q-series approach 关于Ramanujan恒等式的一种q级数方法
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.08
None Bhaskar Srivastava
{"title":"On the identities of Ramanujan – a q-series approach","authors":"None Bhaskar Srivastava","doi":"10.12697/acutm.2023.27.08","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.08","url":null,"abstract":"The idea of this paper is to prove two general theorems using q-series and deduce some partial theta identities and false theta identities. Some of the identities of Ramanujan come as special cases.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135896101","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
Some Galois connections arising from Morita contexts of semigroups 由半群的Morita上下文引起的伽罗瓦连接
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-28 DOI: 10.12697/acutm.2023.27.07
Alvin Lepik
{"title":"Some Galois connections arising from Morita contexts of semigroups","authors":"Alvin Lepik","doi":"10.12697/acutm.2023.27.07","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.07","url":null,"abstract":"We show that a unitary surjective Morita context connecting two semigroups yields Galois connections between certain lattices of compatible relations whenever either semigroup has common weak local units. In the event both semigroups have common weak local units, we obtain mutually inverse lattice isomorphisms that preserve reflexivity, symmetricity and transitivity between the lattices of compatible relations on the semigroups.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135894871","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
Implicit-implicit and parametric-implicit surface intersections in Euclidean n-space 欧几里得n空间中隐式-隐式和参数-隐式曲面相交
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-27 DOI: 10.12697/acutm.2023.27.03
Bedia Merih Özçetin, Mustafa Düldül
{"title":"Implicit-implicit and parametric-implicit surface intersections in Euclidean n-space","authors":"Bedia Merih Özçetin, Mustafa Düldül","doi":"10.12697/acutm.2023.27.03","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.03","url":null,"abstract":"In this paper, we study the intersection problem of two surfaces in which at least one surface is given by its implicit equation in Euclidean n-space. We first obtain the curvatures of the transversal intersection curve of two implicit surfaces. Later, the intersection problem is studied for a parametric surface and an implicit surface in n-dimensional Euclidean space. Finally, we present examples as applications of the given methods.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135951042","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
On the distribution of the greatest common divisor of the elements in integral part sets 关于积分部分集合中元素的最大公因数的分布
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-27 DOI: 10.12697/acutm.2023.27.04
Teerapat Srichan
{"title":"On the distribution of the greatest common divisor of the elements in integral part sets","authors":"Teerapat Srichan","doi":"10.12697/acutm.2023.27.04","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.04","url":null,"abstract":"It is a classical result that the probability that two positive integers n, m ≤ x are relatively prime tends to 1/ζ(2) = 6/π2 as x → ∞. In this paper, the same result is still true when n and m are restricted to sub-sequences, i.e. Piatetski–Shapiro sequence, Beatty sequence and the floor function set.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135950871","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
Specht's ratio and logarithmic mean in time scale dynamic inequalities and their retrospective variants 时间尺度动态不等式中的Specht比值和对数均值及其回溯变量
Acta et Commentationes Universitatis Tartuensis de Mathematica Pub Date : 2023-05-26 DOI: 10.12697/acutm.2023.27.01
Deeba Afzal, Muhammad Jibril Sahir
{"title":"Specht's ratio and logarithmic mean in time scale dynamic inequalities and their retrospective variants","authors":"Deeba Afzal, Muhammad Jibril Sahir","doi":"10.12697/acutm.2023.27.01","DOIUrl":"https://doi.org/10.12697/acutm.2023.27.01","url":null,"abstract":"In this research article, we investigate reverse Radon's inequality, reverse Bergström's inequality, the reverse weighted power mean inequality, reverse Schlömilch's inequality, reverse Bernoulli's inequality and reverse Lyapunov's inequality with Specht's ratio on time scales. We also present reverse Rogers--Holder's inequality with logarithmic mean and Specht's ratio on time scales. The time scale dynamic inequalities unify and extend some continuous inequalities and their corresponding discrete and quantum versions.","PeriodicalId":42426,"journal":{"name":"Acta et Commentationes Universitatis Tartuensis de Mathematica","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134922728","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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