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On Petrenko's Deviations and Complex Difference Equations
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作者 Lipeng XIAO Chunfang CHEN 《Journal of Mathematical Research with Applications》 2026年第2期209-221,共13页
In this paper,the growth characteristic of meromorphic solutions for the following difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=0 with no dominating coefficient is studied.By imposing certain restriction o... In this paper,the growth characteristic of meromorphic solutions for the following difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=0 with no dominating coefficient is studied.By imposing certain restriction on the entire coefficients associated with Petrenko's deviation of the above equation,we obtain some results and partially address a question posed byⅠ.Laine and C.C.Yang.Furthermore,for the entire solutions f(z)of the difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=F(z),where Aj(z)(j=0,…,n),F(z)are entire functions,we discover a close relationship between the measure of common transcendental directions associated with classical difference operators of f(z)and Petrenko's deviations of the coefficients. 展开更多
关键词 complex difference equation difference operator Petrenko’s deviation transcenden-tal direction
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COMPACT DIFFERENCES OF COMPOSITION OPERATORS ON HOLOMORPHIC FUNCTION SPACES IN THE UNIT BALL 被引量:6
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作者 江良英 欧阳才衡 《Acta Mathematica Scientia》 SCIE CSCD 2011年第5期1679-1693,共15页
We find a lower bound for the essential norm of the difference of two composition operators acting on H 2(BN ) or As2 (BN ) (s 1). This result plays an important role in proving a necessary and sufficient condit... We find a lower bound for the essential norm of the difference of two composition operators acting on H 2(BN ) or As2 (BN ) (s 1). This result plays an important role in proving a necessary and sufficient condition for the difference of linear fractional composition operators to be compact, which answers a question posed by MacCluer and Weir in 2005. 展开更多
关键词 composition operators Hardy space Bergman spaces compact differences
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ENTIRE FUNCTIONS SHARING ONE SMALL FUNCTION CM WITH THEIR SHIFTS AND DIFFERENCE OPERATORS 被引量:3
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作者 崔宁 陈宗煊 《Acta Mathematica Scientia》 SCIE CSCD 2017年第3期786-798,共13页
In this article, we mainly devote to proving uniqueness results for entire functionssharing one small function CM with their shift and difference operator simultaneously. Letf(z) be a nonconstant entire function of ... In this article, we mainly devote to proving uniqueness results for entire functionssharing one small function CM with their shift and difference operator simultaneously. Letf(z) be a nonconstant entire function of finite order, c be a nonzero finite complex constant, and n be a positive integer. If f(z), f(z+c), and △n cf(z) share 0 CM, then f(z+c)≡Af(z), where A(≠0) is a complex constant. Moreover, let a(z), b(z)( O) ∈ S(f) be periodic entire functions with period c and if f(z) - a(z), f(z + c) - a(z), △cn f(z) - b(z) share 0 CM, then f(z + c) ≡ f(z). 展开更多
关键词 Entire function SHIFTS difference operators shared values
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CHARACTERIZATIONS OF COMPACT OPERATORS ON SOME EULER SPACES OF DIFFERENCE SEQUENCES OF ORDER m 被引量:2
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作者 Ivana Djolovi Eberhard Malkowsky 《Acta Mathematica Scientia》 SCIE CSCD 2011年第4期1465-1474,共10页
In the past, several authors studied spaces of m-th order difference sequences, among them, H.Polat and F.Basar ([17]) defined the Euler spaces of m-th order difference sequences e r 0 (△ ( m ) ), e r c (△ (... In the past, several authors studied spaces of m-th order difference sequences, among them, H.Polat and F.Basar ([17]) defined the Euler spaces of m-th order difference sequences e r 0 (△ ( m ) ), e r c (△ ( m ) ) and e r ∞ (△ ( m ) ) and characterized some classes of matrix transformations on them. In our paper, we add a new supplementary aspect to their research by characterizing classes of compact operators on those spaces. For that purpose, the spaces are treated as the matrix domains of a triangle in the classical sequence spaces c 0 , c and ∞ . The main tool for our characterizations is the Hausdorff measure of noncompactness. 展开更多
关键词 difference sequence spaces of order m matrix transformations compact operators Hausdorff measure of noncompactness
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LEIBNIZ′FORMULA OF GENERALIZED DIFFERENCE WITH RESPECT TO A CLASS OF DIFFERENTIAL OPERATORS AND RECURRENCE FORMULA OF THEIR GREEN′S FUNCTION 被引量:1
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作者 许跃生 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1984年第3期1359-1364,共6页
In this paper, Leibniz' formula of generalized divided difference with respect to a class of differential operators whose basic sets of solutions have power form, is considered. The recurrence formula of Green fun... In this paper, Leibniz' formula of generalized divided difference with respect to a class of differential operators whose basic sets of solutions have power form, is considered. The recurrence formula of Green function about the operators is also given. 展开更多
关键词 LEIBNIZ S FUNCTION FORMULA OF GENERALIZED difference WITH RESPECT TO A CLASS OF DIFFERENTIAL operators AND RECURRENCE FORMULA OF THEIR GREEN
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MIKUSINSKI'S OPERATORS SOLUTION OF THREE-ORDER LINEAR DIFFERENCE EQUATION WITH VARIABLE COEFFICIENTS
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作者 周之虎 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1994年第1期71-79,共9页
This paper proceeds the papers [3] [4], we make use of the idea of the variable ,number operators and some concepts and conclusions of the shifting operators serieswith variable coefficients in the operational field o... This paper proceeds the papers [3] [4], we make use of the idea of the variable ,number operators and some concepts and conclusions of the shifting operators serieswith variable coefficients in the operational field of Mikusinski, it is devoted to thesolution of the general three-order linear difference equation with variable,coefficients,and it is also devoted to the better solution .formula for the some special three-orderlinear difference equations with variable coefficients, in addition, we try to provide theidea and method for realizing solution of the more than three-order linear differenceequation with variable coefficients. 展开更多
关键词 Mikusinski operator shift operator difference equation
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Differences of Weighted Composition Operators from Mixed-Norm Spaces to Weighted-Type Spaces
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作者 Xianhao ZHAO Yuxia LIANG 《Journal of Mathematical Research with Applications》 CSCD 2012年第5期615-625,共11页
In this paper, we study the boundedness and estimate the essential norm of the differences of weighted composition operators from mixed-norm spaces to weighted-type spaces on the unit ball of CN.
关键词 weighted composition operator mixed-norm spaces weighted-type space essential norm difference.
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Spectrum of a Class of Difference Operators with Indefinite Weights
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作者 Congmin Yang Yunlan Gao Kang Sun 《Journal of Applied Mathematics and Physics》 2020年第4期727-736,共10页
In this study, we use analytical methods and Sylvester inertia theorem to research a class of second order difference operators with indefinite weights and coupled boundary conditions. The eigenvalue problem with sign... In this study, we use analytical methods and Sylvester inertia theorem to research a class of second order difference operators with indefinite weights and coupled boundary conditions. The eigenvalue problem with sign-changing weight has lasted a long time. The number of eigenvalues and the number of sign changes of the corresponding eigenfunctions of discrete equations under different boundary conditions are mainly studied. For the discrete Sturm-Liouville problems, similar conclusions about the properties of eigenvalues and the number of sign changes of the corresponding eigenfunctions are obtained under different boundary conditions, such as periodic boundary conditions, antiperiodic boundary conditions and separated boundary conditions etc. The purpose of this paper is to extend the similar conclusion to the coupled boundary conditions, which is of great significance to the perfection of the theory of the discrete Sturm-Liouville problems. We came to the following conclusions: first, the eigenvalues of the problem are real and single, the number of the positive eigenvalues is equal to the number of positive elements in the weight function, and the number of negative eigenvalues is equal to the number of negative elements in the weight function. Second, under some conditions, we obtain the sign change of the eigenfunction corresponding to the j-th positive/negative eigenvalue. 展开更多
关键词 SPECTRUM difference OPERATOR Coupled BOUNDARY Conditions INDEFINITE WEIGHT
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四网融合之城际铁路与市域铁路互通运营研究
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作者 陈丽 李瑞林 +2 位作者 任志权 柯斌 樊惠惠 《高速铁路技术》 2026年第2期25-32,共8页
四网融合有利于发挥轨道交通网络优势,互通运营是四网融合的重难点,目前尚未有针对性的研究。本研究表明,(1)市域铁路与城际铁路由于技术标准不同,城际铁路下线运行至市域铁路需要改建市域铁路相关基础设施,改建难度极大,建议既有铁路... 四网融合有利于发挥轨道交通网络优势,互通运营是四网融合的重难点,目前尚未有针对性的研究。本研究表明,(1)市域铁路与城际铁路由于技术标准不同,城际铁路下线运行至市域铁路需要改建市域铁路相关基础设施,改建难度极大,建议既有铁路不考虑城际铁路下线市域铁路的运行模式,但市域铁路可利用城际铁路富余能力延伸服务范围。新建铁路根据线路利用率及工程投资,综合比选互通运营方案。(2)目前涉及互通运营的车辆、供电、信号、售检票、通信等相关系统设备厂家还需根据互联互通要求开展产品研发、测试、验证、认证及许可等工作。(3)由于管理体制不同,相关技术政策和运营管理差异大,需制定互通管理体制,以支撑四网融合的可持续发展。 展开更多
关键词 四网融合 不同制式 运营互通
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多工况下汽轮机多级轴封溢流流场特性研究
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作者 万红廷 杨智 +4 位作者 赵天 杨君君 范思毅 彭姝璇 付经伦 《工程热物理学报》 北大核心 2026年第2期451-465,共15页
汽轮机轴端密封是汽轮机的关键部件,在灵活运行条件下研究其宽工况范围内的流场特性对提升设备性能、保障安全运行、降低能耗具有重要意义。本文针对不同工况下,高、中压轴端多级密封内流动、密封及溢流特性的演变规律进行分析,通过数... 汽轮机轴端密封是汽轮机的关键部件,在灵活运行条件下研究其宽工况范围内的流场特性对提升设备性能、保障安全运行、降低能耗具有重要意义。本文针对不同工况下,高、中压轴端多级密封内流动、密封及溢流特性的演变规律进行分析,通过数值模拟获得不同压比下轴封蒸汽流量系数和内部流场,分析轴封进出口压比、各级密封结构对泄漏气流流量、组分以及内部流场的影响。结果表明:随着机组进、出口压比的增加,轴封泄漏量增加,流入蒸汽母管流量增大,密封性能较低的1级轴封匹配密封性能较高的2、3级轴封,有利于保证溢流至轴端加热器中的蒸汽占比减小,提高换热效率;随着缸内压力增大,各级轴封内流场结构基本不变,但齿隙处局部马赫数、轴封腔室旋涡强度及旋涡尺寸会随之增大;但同一结构中,涡强度引起的能量耗散对轴封泄漏量的影响小于压比变化对泄漏量的直接影响;在高压比条件下,双短齿与凸台交错的结构使得中压1级轴封流量系数降低1.5%,而在低压比条件下,增加长齿数量使得高压2、3级轴封流量系数降低约27.36%、10.56%。为了实现对该机组轴封泄漏量的快速评估,分别提出了针对该汽轮机机组高、中压1级轴封段流量系数和溢流量的计算模型,该模型可以快速、准确的预测机组轴封泄漏量和溢流量。 展开更多
关键词 汽轮机 轴端密封 溢流特性 不同工况 数值模拟
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符号压力函数与核差结合的红外图像轮廓分割
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作者 李传真 周斌 +2 位作者 王伟明 闫宁 赵明冬 《红外技术》 北大核心 2026年第3期324-329,共6页
针对红外图像中目标与背景对比度低,难以准确提取目标轮廓的问题,提出一种融合符号压力函数和核差的红外图像主动轮廓分割方法。首先,采用最优核差算子捕获红外图像边界信息,结合全局和局部图像将符号压力函数进行融合,通过变分水平集... 针对红外图像中目标与背景对比度低,难以准确提取目标轮廓的问题,提出一种融合符号压力函数和核差的红外图像主动轮廓分割方法。首先,采用最优核差算子捕获红外图像边界信息,结合全局和局部图像将符号压力函数进行融合,通过变分水平集方法最小化能量泛函,并依据梯度下降流迭代更新水平集;其次,将融合的符号压力函数与核差算子结合,更新主动轮廓位置,使图像分割的主动轮廓尽可能贴近目标边缘;最后,采用高斯滤波器进行水平集函数演变,得到分割结果。实验结果表明,论文提出的红外图像轮廓分割模型的平均准确率为92.93%,平均召回率为93.87%,平均Dice相似系数为0.904。 展开更多
关键词 红外图像 主动轮廓分割 符号压力函数 核差算子 水平集变换
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大型压裂船“海洋石油696”技术现状及未来作业模式展望
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作者 刘宝生 杜建波 《西南石油大学学报(自然科学版)》 北大核心 2026年第1期1-11,共11页
由于海洋环境的独特性,存在施工空间小、投资成本高和产量要求高等难题,给海上规模化压裂带来巨大挑战。大型压裂船及配套关键技术能够充分改造劣质储层,规模化、批量化作业模式能够形成集约化产业优势,降低作业成本,实现海上压裂开发... 由于海洋环境的独特性,存在施工空间小、投资成本高和产量要求高等难题,给海上规模化压裂带来巨大挑战。大型压裂船及配套关键技术能够充分改造劣质储层,规模化、批量化作业模式能够形成集约化产业优势,降低作业成本,实现海上压裂开发的低成本“少井高产”,但相匹配的不同压裂作业模式及配套技术体系有待进一步研究。基于未来海上大规模、批量化压裂作业需求,展望了未来压裂船在地质工程一体化、规模化、压裂生产一体化、配套液体及处理工艺等4个方面的发展方向,并通过系统梳理海上主要作业设施,提出了基于“采油平台+模块钻机或钻井船、无人平台+钻井船或修井船、钻井船探井压裂和导管架期间压裂”4种模式下的压裂管柱及配套井口连接解决方案,为压裂船规模化连续作业提供技术借鉴。 展开更多
关键词 大型压裂船 规模化压裂 不同模式压裂 不同海上设施的作业模式
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基于温频耦合效应和斜抛物线-行波模型的输电线路弧垂计算方法
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作者 周原 苟彬 +3 位作者 彭向阳 席荣军 汪皓 范亚洲 《广东电力》 北大核心 2026年第3期83-96,共14页
全天候实时精准监测输电线路弧垂状态是调整“安全-效率”二元矛盾的关键,针对现有弧垂计算方法在准确性、简洁性等方面的不足,提出基于温频耦合效应和斜抛物线-行波模型的输电线路弧垂计算方法。首先,搭建悬挂点不等高时导线的弧垂模型... 全天候实时精准监测输电线路弧垂状态是调整“安全-效率”二元矛盾的关键,针对现有弧垂计算方法在准确性、简洁性等方面的不足,提出基于温频耦合效应和斜抛物线-行波模型的输电线路弧垂计算方法。首先,搭建悬挂点不等高时导线的弧垂模型,结合行波传输理论,建立斜抛物线-行波关系函数和弧垂模型函数;然后,通过有限元仿真分析温度对线路分布式参数的影响规律,建立温度/频率-波速耦合关系曲线,提出可精准获取行波波头时间和中心频率的河马优化-逐次变分模态分解-对称差分能量算子(HO-SVMD-SDEO)算法;最后,以广东省某220 kV输电线路为研究对象,对所提线路弧垂计算方法的准确性进行验证。研究结果表明所提线路弧垂计算方法所得计算值与实际测量值的偏差在0.02 m以内,相对误差小于0.5%,满足实际工程应用需要。 展开更多
关键词 弧垂 行波 悬挂点不等高 温度 逐次变分模态分解 对称差分能量算子
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基于弛豫时间的不同工况下直接甲醇燃料电池性能退化分析
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作者 王阳达 王建国 +1 位作者 连冠 张大骋 《上海交通大学学报》 北大核心 2026年第2期289-299,共11页
为研究直接甲醇燃料电池(DMFC)在全球统一轻型车辆测试循环(WLTC)和中国轻型汽车测试循环(CLTC)两种不同工况下的性能退化特征,采用极化曲线、等效电路模型和弛豫时间分布(DRT)相结合的方法分析DMFC的退化特征.根据波形演变,利用电化学... 为研究直接甲醇燃料电池(DMFC)在全球统一轻型车辆测试循环(WLTC)和中国轻型汽车测试循环(CLTC)两种不同工况下的性能退化特征,采用极化曲线、等效电路模型和弛豫时间分布(DRT)相结合的方法分析DMFC的退化特征.根据波形演变,利用电化学阻抗谱计算DRT,表征DMFC各极化过程中的退化.结果表明:在WLTC工况下性能的衰退要大于CLTC工况.两种工况下,传质过程阻碍都对DMFC性能退化起主导作用,传质过程阻碍变化率在WLTC工况下为2.39 mΩ/h,CLTC工况下为0.764 mΩ/h;氧还原反应阻碍不受工况影响.在CLTC工况下,其显著的动态波动性和丰富的瞬态工况对质子传输构成较大阻碍,有效降低膜结合水含量,但对传质阻碍的影响较小,促进了氧气扩散速率的提升.根据氧还原反应阻碍的弛豫时间分布,建立一个燃料电池退化模型用于表征DMFC的健康状态,为DMFC运行中的健康状态评估提供了参考. 展开更多
关键词 不同工况 直接甲醇燃料电池 等效电路模型 弛豫时间分布 性能退化特征
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基于双重差分法的铁路客运浮动票价实施效果评价方法研究
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作者 尹璐 孔德越 +2 位作者 王彦驰 刘思佳 王洪业 《铁路计算机应用》 2026年第1期13-17,共5页
为解决铁路客运浮动票价实施与列车运营成效评估过程中存在的潜在内生性问题,提高评估结果的科学性与有效性,提出一种基于双重差分法的浮动票价实施效果评估模型。通过选取不同方向的4条具有代表性的高速铁路线路进行实证分析,在线性回... 为解决铁路客运浮动票价实施与列车运营成效评估过程中存在的潜在内生性问题,提高评估结果的科学性与有效性,提出一种基于双重差分法的浮动票价实施效果评估模型。通过选取不同方向的4条具有代表性的高速铁路线路进行实证分析,在线性回归模型中验证了浮动票价实施效果的显著性,实现了浮动票价策略对铁路客运运营效果影响的定量评价。该方法可为铁路客运管理部门明确政策实施成效、精准施策,以及增运增收提供有效的管理手段与决策支持。 展开更多
关键词 铁路客运浮动票价 铁路运营管理 双重差分法 线性回归 平行趋势检验
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不同工况下安太隧道围岩稳定性数值模拟分析
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作者 王福举 董海龙 +1 位作者 王朋朋 吴骏 《四川建材》 2026年第2期113-116,共4页
以柳州市安太隧道相对薄弱的ZK42+146~ZK42+148段为工程背景,采用ABAQUS动态仿真技术,对无支护工况、实际工况和设计工况条件下,隧道围岩长期稳定性及衬砌单元强度安全系数等进行了数值模拟计算分析。结果表明,隧道围岩在无支护条件下... 以柳州市安太隧道相对薄弱的ZK42+146~ZK42+148段为工程背景,采用ABAQUS动态仿真技术,对无支护工况、实际工况和设计工况条件下,隧道围岩长期稳定性及衬砌单元强度安全系数等进行了数值模拟计算分析。结果表明,隧道围岩在无支护条件下因塑性区快速发展而变形破坏,添加支护后,实际支护强度能够满足控制围岩时间变形的要求,确保其长期稳定;实际及设计工况下的隧道衬砌单元强度安全系数均高于2.3,满足规范要求。研究结果可为安太隧道及类似隧道围岩的稳定性与安全性分析提供参考。 展开更多
关键词 不同工况 安太隧道 稳定性 数值模拟 安全系数
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An Optimal Spatial Finite-Difference Operator which ReducesTruncation Error to a Minimum 被引量:1
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作者 王 元 伍荣生 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2002年第3期468-486,共19页
Highly accurate spatial discretization is essentially required to perform numerical climate and weather prediction. The difference between the differential and the finite-difference operator is however a primitive err... Highly accurate spatial discretization is essentially required to perform numerical climate and weather prediction. The difference between the differential and the finite-difference operator is however a primitive error source in the numerics. This paper presents an optimization of centered finite-difference operator based on the principle of constrained cost function, which can reduce the truncation error to minimum. In the optimization point of view, such optimal operator is in fact an attempt to minimize spatial truncation er-rors in atmospheric modeling, in a simple way and indeed a quite innovative way to implement Variational Continuous Assimilation (VCA) technique. Furthermore, the optimizing difference operator is consciously designed to be meshing-independent, so that it can be used for most Arakawa-mesh configurations, such as un-staggered (Arakawa-A) or com-monly staggered (Arakawa-B, Arakawa-C, Arakawa-D) mesh. But for the calibration purpose, the pro-posed operator is implemented on an un-staggered mesh in which the truncation oscillation is mostly ex-cited, and it thus makes a severe and indeed a benchmark test for the proposed optimal scheme. Both theo-retical investigation and practical modeling indicate that the aforementioned numerical noise can be significantly eliminated. 展开更多
关键词 Finite—difference operator Truncation error OPTIMIZATION
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Properties for Solutions of Nonlinear Functional Difference Equations 被引量:2
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作者 DUANMU Lian-xi 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2005年第3期258-264,共7页
In this paper, some sufficient and necessary conditions are established for the oscillatory of solutions for nonlinear functional difference equations, which extend and improve some corresponding results obtained and ... In this paper, some sufficient and necessary conditions are established for the oscillatory of solutions for nonlinear functional difference equations, which extend and improve some corresponding results obtained and are discrete analogues of the corresponding results for the continuous version. 展开更多
关键词 functional difference equation OSCILLATION increasing operator fixed point theorem
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Finite-difference time-domain studies of low-frequency stop band in superconductor-dielectric superlattice 被引量:1
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作者 王身云 刘少斌 Le-Wei Joshua Li 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第8期374-378,共5页
The transmission coefficients of electromagnetic (EM) waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain (SO-FDTD) method is used in the ... The transmission coefficients of electromagnetic (EM) waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain (SO-FDTD) method is used in the analysis. By using the SO-FDTD method, the transmission spectrum is obtained and its characteristics are investigated for different thicknesses of superconductor layers and dielectric layers, from which a stop band starting from zero frequency can be apparently observed. The relation between this low-frequency stop band and relative temperature, and also the London penetration depth at a superconductor temperature of zero degree are discussed, separately. The low-frequency stop band properties of superconductor-dielectric superlattice thus are well disclosed. 展开更多
关键词 shift operator finite difference time domain method SUPERCONDUCTOR superconductor- dielectric superlattice high-pass filter
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A NOTE ON VALUE DISTRIBUTION OF DIFFERENCE POLYNOMIALS OF MEROMORPHIC FUNCTIONS 被引量:2
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作者 姚丽萍 陈宗煊 《Acta Mathematica Scientia》 SCIE CSCD 2014年第6期1826-1834,共9页
In this paper, we investigate the value distribution of the difference counterpart △f(z)- af(z)^n of f′(z)- af(z)^n and obtain an almost direct difference analogue of result of Hayman.
关键词 shift difference operator order
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