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Product and Commutativity of Slant Toeplitz Operators 被引量:2
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作者 Chaomei LIU Yufeng LU 《Journal of Mathematical Research with Applications》 CSCD 2013年第1期122-126,共5页
In this paper, the product and commutativity of slant Toeplitz operators are discussed. We show that the product of k1^th-order slant Toeplitz operators and k2^th-order slant Toeplitz operators must be a (klk2)^th-o... In this paper, the product and commutativity of slant Toeplitz operators are discussed. We show that the product of k1^th-order slant Toeplitz operators and k2^th-order slant Toeplitz operators must be a (klk2)^th-order slant Toeplitz operator except for zero operators, and the commutativity and essential commutativity of two slant Toeplitz operators with different orders are the same. 展开更多
关键词 Toeplitz operator slant Toeplitz operator PRODUCT commutativity.
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A COMMUTATIVITY CONDITION FOR S-UNITAL RINGS
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作者 Yin Zhiyun Huang Li(Department of Applied Mathematics and Applied Software, Central South University of Technology, Changsha, 410083, China) 《Journal of Central South University》 SCIE EI CAS 1995年第2期81-83,共3页
Let R be an s-unital ring, and we prove a commutativity theorem of R satisfying the following conditions: (l ) For each x, y∈ R,there exist bounded positive integers k =k (x,y), s=s (x,y), t =t (x,y)(where, at least... Let R be an s-unital ring, and we prove a commutativity theorem of R satisfying the following conditions: (l ) For each x, y∈ R,there exist bounded positive integers k =k (x,y), s=s (x,y), t =t (x,y)(where, at least one of k, s, t is not equal to 1) such 展开更多
关键词 s-unital RINGS p-torsion free commutativity
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A Fixed Point Theorem in Intuitionistic Fuzzy Metric Spaces by Using New Commutativity Condition
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作者 Sushil Sharma Bhavana Deshpande 《模糊系统与数学》 CSCD 北大核心 2010年第4期151-161,共11页
We prove a common fixed point theorem for discontinuous,noncompatible mappings on noncomplete intuitionistic fuzzy metric spaces by using a new commutativity condition.We validate our main result by an example.
关键词 Triangular Norms Triangular Conorms Intuitionistic Fuzzy Meuric Spaces (DS)-weak commutativity Common Fixed Points
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Maps Preserving Commutativity up to a Factor on Standard Operator Algebras
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作者 Meiyan JIAO 《Journal of Mathematical Research with Applications》 CSCD 2013年第6期708-716,共9页
Let X, Y be real or complex Banach spaces with dimension greater than 2 and A, B be standard operator algebras on X and Y, respectively. Let φ :A →B be a unital surjective map. In this paper, we characterize the m... Let X, Y be real or complex Banach spaces with dimension greater than 2 and A, B be standard operator algebras on X and Y, respectively. Let φ :A →B be a unital surjective map. In this paper, we characterize the map φ on .4 which satisfies (A - B)R = R(A-B) ξR ((A-B)→ (φ(B))φ(R) =φ(R)((A)- (B)) for A, B, R E .4 and for some scalar 展开更多
关键词 PRESERVERS standard operator algebras commutativity up to a factor.
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Finite Groups with Four Relative Commutativity Degrees
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作者 A. Erfanian M. Farrokhi D.G. 《Algebra Colloquium》 SCIE CSCD 2015年第3期449-458,共10页
It is shown that a finite group G has four relative commutativity degrees if and only if G/Z(G) is a p-group of order p3 and G has no abelian maximal subgroups, or G/Z(G) is a Frobenius group with Frobenius kernel... It is shown that a finite group G has four relative commutativity degrees if and only if G/Z(G) is a p-group of order p3 and G has no abelian maximal subgroups, or G/Z(G) is a Frobenius group with Frobenius kernel and complement isomorphic to Zp × Zp and Zq, respectively, and the Sylow p-subgroup of G is abelian, where p and q are distinct primes. 展开更多
关键词 relative commutativity degree commutativity degree finite group
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Strong Skew Commutativity Preserving Maps on Rings with Involution 被引量:3
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作者 Chang Jing LI Quan Yuan CHEN 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2016年第6期745-752,共8页
Let R be a unital *-ring with the unit I. Assume that R contains a symmetric idempotent P which satisfies ARP= 0 implies A = 0 and AR(I - P) = 0 implies A = 0. In this paper, it is shown that a surjective map Ф:... Let R be a unital *-ring with the unit I. Assume that R contains a symmetric idempotent P which satisfies ARP= 0 implies A = 0 and AR(I - P) = 0 implies A = 0. In this paper, it is shown that a surjective map Ф: R →R is strong skew commutativity preserving (that is, satisfies Ф(A)Ф(B) - Ф(B)Ф(A)* : AB- BA* for all A, B ∈R) if and only if there exist a map f : R → ZSz(R) and an element Z ∈ ZS(R) with Z^2 =I such that Ф(A) =ZA + f(A) for all A ∈ R, where ZS(R) is the symmetric center of R. As applications, the strong skew commutativity preserving maps on unital prime *-rings and von Neumann algebras with no central summands of type I1 are characterized. 展开更多
关键词 Strong skew commutativity preserving von Neumann algebras prime rings
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Two Theorems on the Commutativity of Arbitrary Rings 被引量:1
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作者 Chang Lin FU Xin Song YANG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2001年第1期133-140,共8页
We prove a theorem on the commutativity of the PI ring and use it to generalize a famous theorem of Herstein.
关键词 PI rings commutativity Strong property F_k
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Hyponormal Block Toeplitz Operators on the Weighted Bergman Space with Circulant Symbols
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作者 FU Guangyang ZHOU Jiang 《数学进展》 北大核心 2026年第1期183-191,共9页
In this paper,we present a necessary and sufficient condition for hyponormal block Toeplitz operators T on the vector-valued weighted Bergman space with symbolsΦ(z)=G^(*)(z)+F(z),where F(z)=∑^(N)_(i)=1 A_(i)z^(i)and... In this paper,we present a necessary and sufficient condition for hyponormal block Toeplitz operators T on the vector-valued weighted Bergman space with symbolsΦ(z)=G^(*)(z)+F(z),where F(z)=∑^(N)_(i)=1 A_(i)z^(i)and G(z)=∑^(N)_(i)=1 A_(−i)z^(i),A_(i)ae culants. 展开更多
关键词 block Toeplitz operator hyponormal weighted Bergman space CIRCULANT COMMUTATOR
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Commutativity Conditions for Rings and Generalized 2-CN Rings
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作者 Hua Yao Jianhua Sun Junchao Wei 《Algebra Colloquium》 SCIE CSCD 2021年第1期51-62,共12页
Firstly,the commutativity of rings is investigated in this paper.Let R be a ring with identity.Then we obtain the following commutativity conditions:(1)if for each x∈R\N(R)and each y∈R,(xy)^(k)=x^(k)y^(k)for k=m,m+1... Firstly,the commutativity of rings is investigated in this paper.Let R be a ring with identity.Then we obtain the following commutativity conditions:(1)if for each x∈R\N(R)and each y∈R,(xy)^(k)=x^(k)y^(k)for k=m,m+1,n,n+1,where m and n are relatively prime positive integers,then R is commutative;(2)if for each x∈R\J(R)and each y∈R,(xy)^(k)=y^(k)x^(k)for k=m,m+1,m+2,where m is a positive integer,then R is commutative.Secondly,generalized 2-CN rings,a kind of ring being commutative to some extent,are investigated.Some relations between generalized 2-CN rings and other kinds of rings,such as reduced rings,regular rings,2-good rings,and weakly Abel rings,are presented. 展开更多
关键词 commutativity conditions generalized 2-CN rings regular rings 2-good rings weakly Abel rings
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Construction of MMC-CLCC Hybrid DC Transmission System and Its Power Flow Reversal Control Strategy
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作者 Yechun Xin Xinyuan Zhao +3 位作者 Dong Ding Shuyu Chen Chuanjie Wang Tuo Wang 《Energy Engineering》 2026年第1期460-474,共15页
To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hyb... To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process. 展开更多
关键词 Hybrid HVDC transmission modular multilevel converter(MMC) controllable line commutated converter(CLCC) online power flow reversal full-bridge and half-bridge submodules new energy through dc transmission system
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A Bilinear Sparse Domination for the Maximal Calder´on Commutator with Rough Kernel
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作者 WANG Meizhong ZHAO Junyan 《数学进展》 北大核心 2025年第5期1059-1074,共16页
LetΩbe homogeneous of degree zero,integrable on S^(d−1) and have vanishing moment of order one,a be a function on R^(d) such that ∇a∈L^(∞)(R^(d)).Let T*_(Ω,a) be the maximaloperator associated with the d-dimensional... LetΩbe homogeneous of degree zero,integrable on S^(d−1) and have vanishing moment of order one,a be a function on R^(d) such that ∇a∈L^(∞)(R^(d)).Let T*_(Ω,a) be the maximaloperator associated with the d-dimensional Calder´on commutator defined by T*_(Ωa)f(x):=sup_(ε>0)|∫_(|x-y|>ε)^Ω(x-y)/|x-y|^(d+1)(a(x)-a(y))f(y)dy.In this paper,the authors establish bilinear sparse domination for T*_(Ω,a) under the assumption Ω∈L∞(Sd−1).As applications,some quantitative weighted bounds for T*_(Ω,a) are obtained. 展开更多
关键词 Calderon commutator Fourier transform multiplier operator approximation bilinear sparse domination rough kernel
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Boundedness of the Commutators of Rough Singular Integral Operators on Triebel–Lizorkin Spaces
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作者 LIU Jie GAO Wenhua 《数学进展》 北大核心 2025年第5期1075-1086,共12页
Let Ω be homogeneous of degree zero,integrable on S^(n−1) and have mean value zero,T_(Ω) be the homogeneous singular integral operator with kernel Ω(x)/|x|^(n) and[b,T_(Ω)]be the commutator of T_(Ω)with symbol b∈BMO(... Let Ω be homogeneous of degree zero,integrable on S^(n−1) and have mean value zero,T_(Ω) be the homogeneous singular integral operator with kernel Ω(x)/|x|^(n) and[b,T_(Ω)]be the commutator of T_(Ω)with symbol b∈BMO(R^(n)).In this paper,the authors prove that if sup ζ∈S^(n−1)∫Sn−1^(|Ω(θ)|log^(β)(1/|θ·ζ|)dθ<∞ with β>2,then[b,T_(Ω)]is bounded on Triebel–Lizorkin space F^(0,q)p(R^(n))provided that 1+1/β−1<p,q<β. 展开更多
关键词 rough singular integral operator COMMUTATOR Triebel-Lizorkin space Littlewood-Paley theory
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Compactness of Fractional Calderón Type Commutators on Morrey Spaces
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作者 LI Aobo MEI Ting WEI Qi 《数学进展》 北大核心 2025年第4期858-870,共13页
In this paper,the authors study the fractional Calderon type commutator T_(Ω,α)^(A)and its maximal operator M_(Ω,α)^(A)with kernels having some kinds of Log-type Dini-condition and obtain the compactness on Morrey... In this paper,the authors study the fractional Calderon type commutator T_(Ω,α)^(A)and its maximal operator M_(Ω,α)^(A)with kernels having some kinds of Log-type Dini-condition and obtain the compactness on Morrey spaces L^(p,λ)(R^(n)). 展开更多
关键词 Calderón type commutator COMPACTNESS Log-type Dini-condition Morrey space
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Phragmen-Lindelof Alternative Results for the Linear Viscoelastic Damped Wave Equation
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作者 SHI Jincheng LIU Yan LIN Yiwu 《应用数学》 北大核心 2025年第2期508-516,共9页
In this article,the viscoelastic damped was equation in three-dimensional cylindrical domain were studied by using a second-order differential inequality.We proved a Phragm´en-Lindelof alternative results,i.e.,th... In this article,the viscoelastic damped was equation in three-dimensional cylindrical domain were studied by using a second-order differential inequality.We proved a Phragm´en-Lindelof alternative results,i.e.,the smooth solutions either grow or decay exponentially as the distance from the entry section tends to infinity.Our results can be seen as a version of the Saint-Venant principle. 展开更多
关键词 Fractional integral commutators Variable exponent Herz-Hardy space Variable exponent weak Herz space Variable kernel
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Impact of Short-Term Power Shortage from Low Voltage Ride through and DC Commutation Failure on Power Grid Frequency Stability
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作者 Wenjia Zhang Sixuan Xu +2 位作者 Wanchun Qi Zhuyi Peng Wentao Sun 《Energy Engineering》 2025年第6期2371-2387,共17页
Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation... Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency. 展开更多
关键词 Commutation failure frequency stability LVRT renewable energy short-term power shortage LCCHVDC
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Riding on Four Lanes How a 10-km road expansion project will transform lives in Rwanda’s Masaka and beyond
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作者 《ChinAfrica》 2025年第11期42-43,共2页
For the people of Masaka,Kabuga and Muyumbu in Rwanda,the daily commute often takes longer than it should.A stretch of just 10 km along the Prince House-Giporoso-Masaka road can take half an hour during peak hours.The... For the people of Masaka,Kabuga and Muyumbu in Rwanda,the daily commute often takes longer than it should.A stretch of just 10 km along the Prince House-Giporoso-Masaka road can take half an hour during peak hours.The narrow two-lane artery,clogged with long-haul trucks from the Rwanda-Tanzania border and commuter traffic,has long tested the patience of drivers and pedestrians alike.In May,a long-awaited announcement finally arrived.Rwanda’s Ministry of Infrastructure confirmed plans to expand the road from two lanes to four,adding a 1.2-km flyover at Giporoso-Remera and an underpass to keep tra"c flowing smoothly.The$60.5 million(Rwf86 billion)project will be fully funded by China,a testament to the deepening friendship and cooperation between the two nations.For many residents,it signals the end of years of lost time and daily frustration. 展开更多
关键词 Muyumbu Rwanda Masaka traffic congestion road expansion daily commute expand road Kabuga
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L^(P) BOUNDEDNESS OF COMMUTATOR AND HÖRMANDER CONDITION
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作者 Qixiang YANG Haibo YANG +1 位作者 Chitin HON Tao QIAN 《Acta Mathematica Scientia》 2025年第5期2171-2189,共19页
For 1<p<∞,Coifman-Rochberg-Weiss established L^(p) boundedness of commutators of smooth kernels.Later,many works tried to weaken the smooth condition.In this paper,we extend these mentioned results to the case ... For 1<p<∞,Coifman-Rochberg-Weiss established L^(p) boundedness of commutators of smooth kernels.Later,many works tried to weaken the smooth condition.In this paper,we extend these mentioned results to the case of non-homogeneous but with strong H¨ormander condition.Our main skills lie in wavelet decomposition,wavelet commutators,Hardy-Littlewood maximal operator and Fefferman-Stein's vector-valued maximum function Theorem. 展开更多
关键词 WAVELETS COMMUTATOR Hardy space Hormander condition vector-valued max-imum function Lp boundedness
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Compact Commutators of Bilinear Fractional Integral Operators on Generalized Morrey Spaces
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作者 KU Fuli 《Wuhan University Journal of Natural Sciences》 2025年第5期463-470,共8页
This paper considers compactness of the commutator[b,I_(α)]i(i=1,2),where I_(α)is a bilinear fractional integral operator,and b is a function in generalized Campanato spaces with variable growth condition.The author... This paper considers compactness of the commutator[b,I_(α)]i(i=1,2),where I_(α)is a bilinear fractional integral operator,and b is a function in generalized Campanato spaces with variable growth condition.The author gives sufficient conditions for the compactness of[b,I_(α)],(i=1,2)from the product of generalized Morrey spaces to generalized Morrey spaces. 展开更多
关键词 fractional integral COMMUTATORS COMPACTNESS generalized Campanato spaces generalized Morrey spaces
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COMMUTATOR ESTIMATES FOR VECTOR FIELDS ON BESOV SPACES WITH VARIABLE SMOOTHNESS AND INTEGRABILITY
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作者 BenMahmoud SALAH 《Acta Mathematica Scientia》 2025年第3期771-788,共18页
In this paper we present certain bilinear estimates for commutators on Besov spaces with variable smoothness and integrability,and under no vanishing assumptions on the divergence of vector fields.Such commutator esti... In this paper we present certain bilinear estimates for commutators on Besov spaces with variable smoothness and integrability,and under no vanishing assumptions on the divergence of vector fields.Such commutator estimates are motivated by the study of well-posedness results for some models in incompressible fuid mechanics. 展开更多
关键词 COMMUTATOR vector fields Besov space variable exponent
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Boundedness of the Parametric Littlewood-Paley Operators on Grand Herz-Morrey Spaces with Variable Exponents
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作者 Rui ZHANG Liwei WANG 《Journal of Mathematical Research with Applications》 2025年第5期659-676,共18页
We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish... We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish the boundedness of higher-order commutators ofμ_(S)^(?)andμ_(λ),^(*,?)with BMO functions applying some properties of variable exponents and generalized BMO norms. 展开更多
关键词 parametric Littlewood-Paley operator COMMUTATOR grand Herz-Morrey space variable exponent
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