发布求助
文献互助 智能选刊 最新文献

Acta et commentationes: Ştiinţe Exacte şi ale Naturii最新文献

筛选
英文 中文
Stability of unperturbed motion governed by the ternary differential system of Lyapunov-Darboux type with nonlinearities of degree four 四阶非线性Lyapunov-Darboux型三元微分系统控制的无扰动运动的稳定性
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.57-67
Natalia Neagu, M. Popa, V. Orlov
{"title":"Stability of unperturbed motion governed by the ternary differential system of Lyapunov-Darboux type with nonlinearities of degree four","authors":"Natalia Neagu, M. Popa, V. Orlov","doi":"10.36120/2587-3644.v14i2.57-67","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.57-67","url":null,"abstract":"For the ternary differential system of Lyapunov-Darboux type with nonlinearities of degree four, using the Lie algebra admitted by this system, was obtained the analytic first integral, determined the Lyapunov function and the conditions of stability of the unperturbed motion.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122992648","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
Schroder T-quasigroups of generalized associativity 广义结合性的Schroder t -拟群
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.47-52
V. Shcherbacov
{"title":"Schroder T-quasigroups of generalized associativity","authors":"V. Shcherbacov","doi":"10.36120/2587-3644.v14i2.47-52","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.47-52","url":null,"abstract":"We prolong research of Schroder quasigroups and Schroder T-quasigroups.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134359666","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
Approximation of solutions of boundary value problems for integro-differential equations of the neutral type using a spline function method 用样条函数法逼近中立型积分微分方程边值问题的解
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.7-14
I. Cherevko, A. Dorosh, Ivan Haiuk, A. Pertsov
{"title":"Approximation of solutions of boundary value problems for integro-differential equations of the neutral type using a spline function method","authors":"I. Cherevko, A. Dorosh, Ivan Haiuk, A. Pertsov","doi":"10.36120/2587-3644.v14i2.7-14","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.7-14","url":null,"abstract":"Boundary value problems for nonlinear integro-differential equations of the neutral type are investigated. A scheme for approximating the boundary value problem solution using cubic splines of defect two is proposed and substantiated. A model example illustrating the proposed approximation scheme is considered.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124715420","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
Centers of cubic differential systems with the line at infinity of maximal multiplicity 无穷远处具有极大多重性的三次微分系统的中心
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.38-46
A. Suba
{"title":"Centers of cubic differential systems with the line at infinity of maximal multiplicity","authors":"A. Suba","doi":"10.36120/2587-3644.v14i2.38-46","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.38-46","url":null,"abstract":"We classify all cubic differential systems with a center-focus critical point and the line at infinity of maximal multiplicity. It is proved that the critical point is of the center type if and only if the divergence of vector field associated to differential system vanishes.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"332 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132301353","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 left product, the right product and the theories of relative torsion 左积，右积和相对扭转理论
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.81-87
A. Turcanu
{"title":"The left product, the right product and the theories of relative torsion","authors":"A. Turcanu","doi":"10.36120/2587-3644.v14i2.81-87","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.81-87","url":null,"abstract":"It is demonstrated that any theory of relative torsion is defined by the left and the right products.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131129331","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 regular operators on Banach lattices Banach格上的正则算子
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.53-56
O. Gok
{"title":"On regular operators on Banach lattices","authors":"O. Gok","doi":"10.36120/2587-3644.v14i2.53-56","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.53-56","url":null,"abstract":"Let $E$ and $F$ be Banach lattices and $X$ and $Y$ be Banach spaces. A linear operator $T: E rightarrow F$ is called regular if it is the difference of two positive operators. $L_{r}(E,F)$ denotes the vector space of all regular operators from $E$ into $F$. A continuous linear operator $T: E rightarrow X$ is called $M$-weakly compact operator if for every disjoint bounded sequence $(x_{n})$ in $E$, we have $lim_{n rightarrowinfty} | Tx_{n} | =0$. $W^{r}_{M}(E,F)$ denotes the regular $M$-weakly compact operators from $E$ into $F$. This paper is devoted to the study of regular operators and $M$-weakly compact operators on Banach lattices. We show that $F$ has a b-property if and only if $L_{r}(E,F)$ has b-property. Also, $W^{r}_{M}(E,F)$ is a $KB$-space if and only if $F$ is a $KB$-space.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124188816","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
Phase portraits of some polynomial differential systems with maximal multiplicity of the line at the infinity 一些多项式微分系统在无穷远处具有极大的直线多重性的相图
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.68-80
Vadim Repesco
{"title":"Phase portraits of some polynomial differential systems with maximal multiplicity of the line at the infinity","authors":"Vadim Repesco","doi":"10.36120/2587-3644.v14i2.68-80","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.68-80","url":null,"abstract":"The present study delves into the investigation of phase portraits of polynomial differential systems, which are systems of differential equations of the form $frac{dx}{dt} = P(x,y), frac{dy}{dt} = Q(x,y)$, where $x$ and $y$ are the dependent variables and $t$ is the independent variable. The functions $P(x,y)$ and $Q(x,y)$ are polynomials in $x$ and $y$. The main objective of this research is to obtain the phase portraits of polynomial differential systems of degree $nin { 3, 4, 5}$ and having an invariant straight line at the infinity of maximal multiplicity.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"57 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126073271","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
Extension of linear operators with application 线性算子的推广及其应用
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.24-37
V. Neagu, Diana Bîclea
{"title":"Extension of linear operators with application","authors":"V. Neagu, Diana Bîclea","doi":"10.36120/2587-3644.v14i2.24-37","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.24-37","url":null,"abstract":"The article presents a method for solving characteristic singular integral equations perturbed with compact operators. The method consists in reducing the solution of these equations to the solution of the systems of singular (unperturbed) equations, which are solved by factoring the coefficients of the obtained systems. The method presented concerns some results of Gohberg and Krupnik and can be used in solving other classes of functional equations with composite operators that fit into the scheme described by Theorem 1.1.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129441058","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
Problems of the theory of invariants and Lie algebras applied in the qualitative theory of differential systems 不变量理论及李代数在微分系统定性理论中的应用问题
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2023-01-01 DOI: 10.36120/2587-3644.v14i2.15-23
M. Popa
{"title":"Problems of the theory of invariants and Lie algebras applied in the qualitative theory of differential systems","authors":"M. Popa","doi":"10.36120/2587-3644.v14i2.15-23","DOIUrl":"https://doi.org/10.36120/2587-3644.v14i2.15-23","url":null,"abstract":"In this work there were formulated 18 problems from the theory of invariant processes, Lie algebras, commutative graded algebras, generating functions and Hilbert series, orbit theory and Lyapunov stability theory that are important to be solved. There was substantiated the necessity of using the solutions of these problems in the qualitative theory of differential systems.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116479658","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
Use of natural pigments obtained from cyanobacteria and algae 使用从蓝藻和藻类中获得的天然色素
Acta et commentationes: Ştiinţe Exacte şi ale Naturii Pub Date : 2022-11-01 DOI: 10.36120/2587-3644.v13i1.110-115
A. Trofim, Anastasia Verdes
{"title":"Use of natural pigments obtained from cyanobacteria and algae","authors":"A. Trofim, Anastasia Verdes","doi":"10.36120/2587-3644.v13i1.110-115","DOIUrl":"https://doi.org/10.36120/2587-3644.v13i1.110-115","url":null,"abstract":"The article reflects data on the use of cyanobacteria pigments in cosmetology. One of the sources of natural antioxidants are the pigments obtained from various algae and cyanobacteria. An essential source for extracting pigments and biologically active substances used in cosmetology, pharmaceuticals, etc. is represented by algae and cyanobacteria. Also, the extracts from cyanobacteria have an important role in the anti-wrinkle effect. Useful pigments include: carotenoids, xanthophylls, astaxanthin, fucoxanthin, chlorophyll, phycoerythrin.","PeriodicalId":340784,"journal":{"name":"Acta et commentationes: Ştiinţe Exacte şi ale Naturii","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126516480","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
下一页 尾页
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整，为了账户安全，请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们：info@booksci.cn Book学术提供免费学术资源搜索服务，方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号：481959085
Book学术官方微信