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Optimal convex approximations of qubit states based on l_(1)-norm of coherence
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作者 Li-Qiang Zhang Yan-Dong Du Chang-Shui Yu 《Chinese Physics B》 2025年第8期475-491,共17页
Determining the minimal distance between the target state and the convex combination of given states is a fundamental problem in quantum resource theory,offering critical guidance for experimental implementations.In t... Determining the minimal distance between the target state and the convex combination of given states is a fundamental problem in quantum resource theory,offering critical guidance for experimental implementations.In this paper,we embark on an in-depth exploration of the use of a quantum state prepared by the convex combination of given qubit states to optimally approximate the l_(1)-norm of coherence of the target quantum state,striving to make the prepared state and the target state as similar as possible.Here,we present the analytical solution for the optimal distance for any N given quantum states.We find that the optimal approximation problem for any N>4 quantum states can be transformed into an optimal approximation problem for no more than four quantum states,which not only significantly streamlines the problem but also proves advantageous for laboratories in terms of material conservation.Ultimately,a one-to-one comparison between the analytical and numerical solutions verifies the effectiveness of our approach. 展开更多
关键词 quantum information processing quantum resource theory quantum coherence optimal convex approximations
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Strong Uniqueness of Best Approximations from RS-sets in Banach Spaces 被引量:1
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作者 何金苏 李冲 《Journal of Southeast University(English Edition)》 EI CAS 2001年第1期70-72,共3页
The problem of strong uniqueness of best approximation from an RS set in a Banach space is considered. For a fixed RS set G and an element x∈X , we proved that the best approximation g * to x from ... The problem of strong uniqueness of best approximation from an RS set in a Banach space is considered. For a fixed RS set G and an element x∈X , we proved that the best approximation g * to x from G is strongly unique. 展开更多
关键词 best approximation RS set strong uniqueness
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Quality-guaranteed Dubins Path Planning for USV Based on Mixed-integer Piecewise linear Programming for Addressing the Extended Minimum-time Intercept Problem
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作者 Xing Zhou Kelin Zhu +3 位作者 Shuang Liu Zhaoqing Li Wenxin Zhang Kang Du 《哈尔滨工程大学学报(英文版)》 2026年第1期216-227,共12页
During the use of robotics in applications such as antiterrorism or combat,a motion-constrained pursuer vehicle,such as a Dubins unmanned surface vehicle(USV),must get close enough(within a prescribed zero or positive... During the use of robotics in applications such as antiterrorism or combat,a motion-constrained pursuer vehicle,such as a Dubins unmanned surface vehicle(USV),must get close enough(within a prescribed zero or positive distance)to a moving target as quickly as possible,resulting in the extended minimum-time intercept problem(EMTIP).Existing research has primarily focused on the zero-distance intercept problem,MTIP,establishing the necessary or sufficient conditions for MTIP optimality,and utilizing analytic algorithms,such as root-finding algorithms,to calculate the optimal solutions.However,these approaches depend heavily on the properties of the analytic algorithm,making them inapplicable when problem settings change,such as in the case of a positive effective range or complicated target motions outside uniform rectilinear motion.In this study,an approach employing a high-accuracy and quality-guaranteed mixed-integer piecewise-linear program(QG-PWL)is proposed for the EMTIP.This program can accommodate different effective interception ranges and complicated target motions(variable velocity or complicated trajectories).The high accuracy and quality guarantees of QG-PWL originate from elegant strategies such as piecewise linearization and other developed operation strategies.The approximate error in the intercept path length is proved to be bounded to h^(2)/(4√2),where h is the piecewise length. 展开更多
关键词 Minimum-time intercept problem Dubins vehicle Mixed-integer piecewise-linear program LINEARIZATION Approximate error trigonometric function USV
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圆形网格抽样和逆近邻优化的密度峰值聚类算法
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作者 赵嘉 何超凡 +2 位作者 肖人彬 曹浩 樊棠怀 《工程科学学报》 北大核心 2026年第1期161-176,共16页
密度峰值聚类(DPC)算法是一种简单高效的聚类算法,因其可直观和快速发现数据集中的类簇而得到广泛关注.但DPC算法需计算所有样本间的欧氏距离,算法的时间复杂度较高;局部密度定义未考虑类簇间密度差异影响,易误选类簇中心;使用链式分配... 密度峰值聚类(DPC)算法是一种简单高效的聚类算法,因其可直观和快速发现数据集中的类簇而得到广泛关注.但DPC算法需计算所有样本间的欧氏距离,算法的时间复杂度较高;局部密度定义未考虑类簇间密度差异影响,易误选类簇中心;使用链式分配策略,易产生错误连带效应.因此,本文提出一种圆形网格抽样和逆近邻优化的密度峰值聚类算法.该算法采用圆形网格抽样得到代表以减少需要计算的样本数,降低算法计算的时间开销,并引入近似K近邻策略加强代表和初始样本的联系,减少抽样导致的聚类精度丢失;利用逆近邻优化局部密度定义策略,根据样本所处环境调节其局部密度的大小,准确找到密度峰值;通过共享逆近邻计算相似性,由相似性矩阵分配代表,避免样本分配策略产生的错误连带效应.设置了复杂形态合成数据集、真实数据集和较大规模数据集进行分组实验.实验结果表明,本文算法在复杂形态、真实及较大规模数据集上聚类优势显著,精度与效率较DPC算法及其他基于DPC的改进算法均有较大提升. 展开更多
关键词 密度峰值聚类 圆形网格抽样 近似K近邻 逆近邻 共享逆近邻
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Operators of Approximations and Approximate Power Set Spaces 被引量:5
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作者 张贤勇 莫智文 舒兰 《Journal of Electronic Science and Technology of China》 CAS 2004年第2期94-96,共3页
Boundary inner and outer operators are introduced, and union, intersection, complement operators of approximations are redefined. The approximation operators have a good property of maintaining union, intersection, co... Boundary inner and outer operators are introduced, and union, intersection, complement operators of approximations are redefined. The approximation operators have a good property of maintaining union, intersection, complement operators, so the rough set theory has been enriched from the operator-oriented and set-oriented views. Approximate power set spaces are defined, and it is proved that the approximation operators are epimorphisms from power set space to approximate power set spaces. Some basic properties of approximate power set space are got by epimorphisms in contrast to power set space. 展开更多
关键词 rough sets approximation operators operators of approximations power set space approximate power set spaces
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POINTWISE CONVERGENCE RATE OF VANISHING VISCOSITY APPROXIMATIONS FOR SCALAR CONSERVATION LAWS WITH BOUNDARY 被引量:3
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作者 刘红霞 潘涛 《Acta Mathematica Scientia》 SCIE CSCD 2009年第1期111-128,共18页
This article is concerned with the pointwise error estimates for vanishing vis- cosity approximations to scalar convex conservation laws with boundary.By the weighted error function and a bootstrap extrapolation techn... This article is concerned with the pointwise error estimates for vanishing vis- cosity approximations to scalar convex conservation laws with boundary.By the weighted error function and a bootstrap extrapolation technique introduced by Tadmor-Tang,an optimal pointwise convergence rate is derived for the vanishing viscosity approximations to the initial-boundary value problem for scalar convex conservation laws,whose weak entropy solution is piecewise C 2 -smooth with interaction of elementary waves and the ... 展开更多
关键词 Scalar conservation laws with boundary vanishing viscosity approximations error estimate pointwise convergence rate transport inequality
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Basic belief assignment approximations using degree of non-redundancy for focal element 被引量:3
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作者 Yi YANG Deqiang HAN Jean DEZERT 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2019年第11期2503-2515,共13页
Dempster-Shafer evidence theory, also called the theory of belief function, is widely used for uncertainty modeling and reasoning. However, when the size and number of focal elements are large, the evidence combinatio... Dempster-Shafer evidence theory, also called the theory of belief function, is widely used for uncertainty modeling and reasoning. However, when the size and number of focal elements are large, the evidence combination will bring a high computational complexity. To address this issue,various methods have been proposed including the implementation of more efficient combination rules and the simplifications or approximations of Basic Belief Assignments(BBAs). In this paper,a novel principle for approximating a BBA into a simpler one is proposed, which is based on the degree of non-redundancy for focal elements. More non-redundant focal elements are kept in the approximation while more redundant focal elements in the original BBA are removed first. Three types of degree of non-redundancy are defined based on three different definitions of focal element distance, respectively. Two different implementations of this principle for BBA approximations are proposed including a batch and an iterative type. Examples, experiments, comparisons and related analyses are provided to validate proposed approximation approaches. 展开更多
关键词 BBA approximation Belief functions Evidence theory Focal element Non-redundancy
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广义离散系统的参数化离散Walsh函数模型降阶方法
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作者 郭海平 郭琦 +1 位作者 余佳微 唐升国 《应用数学》 北大核心 2026年第1期12-21,共10页
针对广义离散系统,提出一种基于离散Walsh函数的参数化降阶新方法.首先将一般的广义离散系统转化为特定类型的广义离散系统,再采用参数嵌入技术,将其转换成离散参数系统.利用嵌入的参数对状态方程进行Taylor级数展开,得到相关的系数方程... 针对广义离散系统,提出一种基于离散Walsh函数的参数化降阶新方法.首先将一般的广义离散系统转化为特定类型的广义离散系统,再采用参数嵌入技术,将其转换成离散参数系统.利用嵌入的参数对状态方程进行Taylor级数展开,得到相关的系数方程.再利用离散Walsh函数及其性质对该所得方程进行展开,得到并求解相应的矩阵方程,以获取离散Walsh函数的系数矩阵.进而通过该系数矩阵计算正交投影矩阵,最终实现广义离散系统的降阶.在理论上证明降阶系统有与原始系统的前几个离散Walsh函数展开系数匹配的性质.选取电力系统电磁暂态仿真对应的微分动力系统进行数值实验,进一步验证提出的方法具有较高的降阶精度和降阶效率. 展开更多
关键词 离散Walsh函数逼近 广义离散系统 模型降阶方法 系数匹配
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Well-Posedness and Finite Element Approximations for Elliptic SPDEs with Gaussian Noises 被引量:2
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作者 Yanzhao Cao Jialin Hong Zhihui Liu 《Communications in Mathematical Research》 CSCD 2020年第2期113-127,共15页
The paper studies the well-posedness and optimal error estimates of spectral finite element approximations for the boundary value problems of semi-linear elliptic SPDEs driven by white or colored Gaussian noises.The n... The paper studies the well-posedness and optimal error estimates of spectral finite element approximations for the boundary value problems of semi-linear elliptic SPDEs driven by white or colored Gaussian noises.The noise term is approximated through the spectral projection of the covariance operator,which is not required to be commutative with the Laplacian operator.Through the convergence analysis of SPDEs with the noise terms replaced by the projected noises,the well-posedness of the SPDE is established under certain covariance operator-dependent conditions.These SPDEs with projected noises are then numerically approximated with the finite element method.A general error estimate framework is established for the finite element approximations.Based on this framework,optimal error estimates of finite element approximations for elliptic SPDEs driven by power-law noises are obtained.It is shown that with the proposed approach,convergence order of white noise driven SPDEs is improved by half for one-dimensional problems,and by an infinitesimal factor for higher-dimensional problems. 展开更多
关键词 Elliptic stochastic partial differential equation spectral approximations finite element approximations power-law noise
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Convergence of Invariant Measures of Truncation Approximations to Markov Processes 被引量:2
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作者 Andrew G. Hart Richard L. Tweedie 《Applied Mathematics》 2012年第12期2205-2215,共11页
Let Q be the Q-matrix of an irreducible, positive recurrent Markov process on a countable state space. We show that, under a number of conditions, the stationary distributions of the n × n north-west corner augme... Let Q be the Q-matrix of an irreducible, positive recurrent Markov process on a countable state space. We show that, under a number of conditions, the stationary distributions of the n × n north-west corner augmentations of Q converge in total variation to the stationary distribution of the process. Two conditions guaranteeing such convergence include exponential ergodicity and stochastic monotonicity of the process. The same also holds for processes dominated by a stochastically monotone Markov process. In addition, we shall show that finite perturbations of stochastically monotone processes may be viewed as being dominated by a stochastically monotone process, thus extending the scope of these results to a larger class of processes. Consequently, the augmentation method provides an attractive, intuitive method for approximating the stationary distributions of a large class of Markov processes on countably infinite state spaces from a finite amount of known information. 展开更多
关键词 Invariant Measure TRUNCATION Approximation Augmentation EXPONENTIAL ERGODICITY Stochastic MONOTONICITY MARKOV Process
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A meshless algorithm with moving least square approximations for elliptic Signorini problems 被引量:1
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作者 王延冲 李小林 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第9期35-42,共8页
Based on the moving least square (MLS) approximations and the boundary integral equations (BIEs), a meshless algorithm is presented in this paper for elliptic Signorini problems. In the algorithm, a projection ope... Based on the moving least square (MLS) approximations and the boundary integral equations (BIEs), a meshless algorithm is presented in this paper for elliptic Signorini problems. In the algorithm, a projection operator is used to tackle the nonlinear boundary inequality conditions. The Signorini problem is then reformulated as BIEs and the unknown boundary variables are approximated by the MLS approximations. Accordingly, only a nodal data structure on the boundary of a domain is required. The convergence of the algorithm is proven. Numerical examples are given to show the high convergence rate and high computational efficiency of the presented algorithm. 展开更多
关键词 meshless method Signorini problem moving least square approximations CONVERGENCE
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Generalized Galerkin Approximations for Pseudoinverses and Operator Equations of the First Kind 被引量:1
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作者 DU Nailin 《Wuhan University Journal of Natural Sciences》 CAS 2006年第3期486-492,共7页
The main result of this paper is a basic theorem about generalized Galerkin approximations for pseudoinverses and operator equations of the first kind, which is presented as follows :Let H be a Hilbert space, { Hn } ... The main result of this paper is a basic theorem about generalized Galerkin approximations for pseudoinverses and operator equations of the first kind, which is presented as follows :Let H be a Hilbert space, { Hn } a sequence of closed subspaces of H, Pn the orthogonal projection of H onto Hn, A∈B(H) and An∈B(Hn). Suppose s-lim↑n→∞Hn=H, lim↑n→∞||Pn°(A-An) ||n=0,-↑R(An)=R(An)(n∈N). Then the following four propositions are equivalent : (a) sup↑n∈Nv∈An^-1 inf ||υ||〈∞ if un∈R(An) and lim↑n→∞un=0; (b) sup↑n∈N|| An || 〈∞; (c) if un∈R(An) and lim↑n→∞ un=u, then u∈R(A) and s-lim↑n→∞An^-1(un)=A^-1(u); (d) if un∈R(An) and lim↑n→∞un=u.then u∈R(A) and lim↑n→∞Au^+(un)=A^+(u). Furtherrnore, if any of the above propositions holds, we have thin N(A)=s-lim↑n→∞N(An ),R(A) = s-lim↑n→∞R(An ), -↑R(A) =R(A). 展开更多
关键词 Galerkin approximation PSEUDOINVERSE CONVERGENCE
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Notes on Rough Set Approximations and Associated Measures 被引量:1
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作者 YAO Yiyu 《浙江海洋学院学报(自然科学版)》 CAS 2010年第5期399-410,共12页
We review and compare two definitions of rough set approximations.One is defined by a pair of sets in the universe and the other by a pair of sets in the quotient universe.The latter definition,although less studied,i... We review and compare two definitions of rough set approximations.One is defined by a pair of sets in the universe and the other by a pair of sets in the quotient universe.The latter definition,although less studied,is semantically superior for interpreting rule induction and is closely related to granularity switching in granular computing.Numerical measures about the accuracy and quality of approximations are examined.Several semantics difficulties are commented. 展开更多
关键词 Accuracy measures GRANULARITY Rough set approximations ROUGHNESS
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PROJECTION METHODS AND APPROXIMATIONS FOR ORDINARY DIFFERENTIAL EQUATIONS 被引量:1
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作者 A. Bensebah F. Dubeau J. Gelinas 《Analysis in Theory and Applications》 1997年第3期78-90,共13页
A formulation of a differential equation as projection and fixed point pi-Mem alloivs approximations using general piecnvise functions. We prone existence and uniqueness of the up proximate solution* convergence in th... A formulation of a differential equation as projection and fixed point pi-Mem alloivs approximations using general piecnvise functions. We prone existence and uniqueness of the up proximate solution* convergence in the L2 norm and nodal supercnnvergence. These results generalize those obtained earlier by Hulme for continuous piecevjise polynomials and by Delfour-Dubeau for discontinuous pieceuiise polynomials. A duality relationship for the two types of approximations is also given. 展开更多
关键词 PROJECTION METHODS AND approximations FOR ORDINARY DIFFERENTIAL EQUATIONS ODE
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The Influence of the Exchange-Correlation Functional on the Non-Interacting Kinetic Energy and Its Implications for Orbital-Free Density Functional Approximations
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作者 FINZEL Kati BULTINCK Patrick 《物理化学学报》 SCIE CAS CSCD 北大核心 2018年第6期650-655,共6页
In this work it is shown that the kinetic energy and the exchange-correlation energy are mutual dependent on each other.This aspect is first derived in an orbital-free context.It is shown that the total Fermi potentia... In this work it is shown that the kinetic energy and the exchange-correlation energy are mutual dependent on each other.This aspect is first derived in an orbital-free context.It is shown that the total Fermi potential depends on the density only,the individual parts,the Pauli kinetic energy and the exchange-correlation energy,however,are orbital dependent and as such mutually influence each other.The numerical investigation is performed for the orbital-based non-interacting Kohn-Sham system in order to avoid additional effects due to further approximations of the kinetic energy.The numerical influence of the exchange-correlation functional on the non-interacting kinetic energy is shown to be of the orderof a few Hartrees.For chemical purposes,however,the energetic performance as a function of the nuclear coordinates is much more important than total energies.Therefore,the effect on the bond dissociation curve was studied exemplarily for the carbon monoxide.The data reveals that,the mutual influence between the exchange-correlation functional and the kinetic energy has a significant influence on bond dissociation energies and bond distances.Therefore,the effect of the exchange-correlation treatment must be considered in the design of orbital-free density functional approximations for the kinetic energy. 展开更多
关键词 The Influence of the EXCHANGE-CORRELATION FUNCTIONAL the Non-Interacting Kinetic Energy Density FUNCTIONAL approximations
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Improved Analytical Approximations to the Scattering Solutions of the Schrdinger Equation with a Hyperbolical Potential
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作者 尤源 陆法林 +1 位作者 孙东升 陈昌远 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第9期315-319,共5页
Using an improved approximate formula to the centrifugal term, we present arbitrary l-state scattering solutions of the hyperbolic potential. The approximate analytical formula of scattering phase shifts and normalize... Using an improved approximate formula to the centrifugal term, we present arbitrary l-state scattering solutions of the hyperbolic potential. The approximate analytical formula of scattering phase shifts and normalized wavefunctions are presented. All data calculated by the above approximate analytical formula are compared with those obtained by using the numerical integration method in the scattering state cases. We find that this improved approximate formula is better than previous one since the calculated results are in good agreement with those exact ones. 展开更多
关键词 HYPERBOLIC POTENTIAL SCATTERING SOLUTIONS analytical approximations
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The Caputo–Fabrizio time-fractional Sharma–Tasso–Olver–Burgers equation and its valid approximations
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作者 Kamyar Hosseini Mousa Ilie +3 位作者 Mohammad Mirzazadeh Dumitru Baleanu Choonkil Park Soheil Salahshour 《Communications in Theoretical Physics》 SCIE CAS CSCD 2022年第7期21-29,共9页
Studying the dynamics of solitons in nonlinear time-fractional partial differential equations has received substantial attention,in the last decades.The main aim of the current investigation is to consider the time-fr... Studying the dynamics of solitons in nonlinear time-fractional partial differential equations has received substantial attention,in the last decades.The main aim of the current investigation is to consider the time-fractional Sharma–Tasso–Olver–Burgers(STOB)equation in the Caputo–Fabrizio(CF)context and obtain its valid approximations through adopting a mixed approach composed of the homotopy analysis method(HAM)and the Laplace transform.The existence and uniqueness of the solution of the time-fractional STOB equation in the CF context are investigated by demonstrating the Lipschitz condition forφ(x,t;u)as the kernel and giving some theorems.To illustrate the CF operator effect on the dynamics of the obtained solitons,several two-and threedimensional plots are formally considered.It is shown that the mixed approach is capable of producing valid approximations to the time-fractional STOB equation in the CF context. 展开更多
关键词 time-fractional Sharma-Tasso-Olver-Burgers equation Caputo-Fabrizio context mixed approach existence and uniqueness valid approximations
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Diffusion approximations for multiclass queueing networks under preemptive priority service discipline
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作者 戴万阳 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第10期1331-1342,共12页
We prove a heavy traffic limit theorem to justify diffusion approximations for multiclass queueing networks under preemptive priority service discipline and provide effective stochastic dynamical models for the system... We prove a heavy traffic limit theorem to justify diffusion approximations for multiclass queueing networks under preemptive priority service discipline and provide effective stochastic dynamical models for the systems. Such queueing networks appear typically in high-speed integrated services packet networks about telecommunication system. In the network, there is a number of packet traffic types. Each type needs a number of job classes (stages) of processing and each type of jobs is assigned the same priority rank at every station where it possibly receives service. Moreover, there is no inter-routing among different traffic types throughout the entire network. 展开更多
关键词 queueing network preemptive priority heavy traffic semimartingale re-flecting Brownian motion fluid model diffusion approximation Lyapunov function
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A Study of Weighted Polynomial Approximations with Several Variables (II)
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作者 Ryozi Sakai 《Applied Mathematics》 2017年第9期1239-1256,共18页
In this paper we investigate weighted polynomial approximations with several variables. Our study relates to the approximation for by weighted polynomial. Then we will give some results relating to the Lagrange interp... In this paper we investigate weighted polynomial approximations with several variables. Our study relates to the approximation for by weighted polynomial. Then we will give some results relating to the Lagrange interpolation, the best approximation, the Markov-Bernstein inequality and the Nikolskii- type inequality. 展开更多
关键词 WEIGHTED POLYNOMIAL approximations the LAGRANGE INTERPOLATION the Best of Approximation INEQUALITIES
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