期刊文献+
共找到44篇文章
< 1 2 3 >
每页显示 20 50 100
基于代数三角基的Quasi-Hermite曲线的构造与研究 被引量:1
1
作者 施群 游清宁 马成良 《计算机集成制造系统》 EI CSCD 北大核心 2009年第2期406-411,共6页
数控系统的插补算法中常采用的Hermite样条曲线,由于算法递推速度低且逼近精度较差,限制了它在中高档数控系统实时插补中的应用。通过研究数控系统的样条曲线构造特点及其和CAD/CAM系统的样条曲线之间的关联,采用最佳平方逼近,并结合幅... 数控系统的插补算法中常采用的Hermite样条曲线,由于算法递推速度低且逼近精度较差,限制了它在中高档数控系统实时插补中的应用。通过研究数控系统的样条曲线构造特点及其和CAD/CAM系统的样条曲线之间的关联,采用最佳平方逼近,并结合幅值、相位、摄动量的优化,在代数三角混合空间Γn=span{1,cost,sint,…,cosnt,sinnt}中,构造了一组高精度的基函数,生成了Quasi-Hermite曲线。应用该算法进行的数控系统插补实验中,不仅新样条曲线的递推插补运算速度提高了14.5%,而且逼近精度达到了10-4数量级,结果表明,基于新曲线的插补算法在提高了轮廓加工轨迹精度的同时,也提高了加工效率,满足了中高档数控平台中样条曲线的构造要求。 展开更多
关键词 数控系统 样条曲线 高精度 样条插补 代数三角样条
下载PDF
代数双曲三角函数空间中的一组正交基 被引量:8
2
作者 李亚娟 汪国昭 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2008年第4期464-468,共5页
利用代数双曲三角函数空间Γn=span{1,sin t,cos t,sinh t,cosh t,t,t2,…,tn-4}中拟Bézier基的对称性构造了一组正交基,并给出该正交基和拟B啨zier基之间的转换矩阵.进一步,应用最小二乘法对代数双曲三角B啨zier曲线进行了保端点... 利用代数双曲三角函数空间Γn=span{1,sin t,cos t,sinh t,cosh t,t,t2,…,tn-4}中拟Bézier基的对称性构造了一组正交基,并给出该正交基和拟B啨zier基之间的转换矩阵.进一步,应用最小二乘法对代数双曲三角B啨zier曲线进行了保端点降阶逼近. 展开更多
关键词 代数双曲三角Bézier 正交 转化 保端点 降阶逼近
下载PDF
几乎代数基与有界完备domain 被引量:1
3
作者 陈煜 寇辉 《四川师范大学学报(自然科学版)》 CAS 北大核心 2018年第1期9-14,共6页
研究几乎代数dcpo的性质,并得到如下主要结果:1)具有可数几乎代数弱闭基的有界完备domain构成的范畴是Cartesian闭的;2)对每个具有(可数)几乎代数基的dcpo,其相容下幂domain是一个具有可数几乎代数弱闭基的有界完备domain.
关键词 几乎代数 有界完备domain 相容下幂domain Cartesian闭范畴
下载PDF
代数双曲B样条基的几乎严格全正性 被引量:1
4
作者 魏炜立 汪国昭 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2014年第2期258-262,271,共6页
样条基的几乎严格全正性和曲线插值适定性关系密切,是几何造型中一个基本且重要的问题.文中证明了代数双曲B样条基具有几乎严格全正性:首先引入代数双曲B样条函数,通过嵌入节点算法推导出函数的零点数和变差数之间的关系;进一步,利用数... 样条基的几乎严格全正性和曲线插值适定性关系密切,是几何造型中一个基本且重要的问题.文中证明了代数双曲B样条基具有几乎严格全正性:首先引入代数双曲B样条函数,通过嵌入节点算法推导出函数的零点数和变差数之间的关系;进一步,利用数学归纳法证明了该基具有几乎严格全正性.文中的证明方法直观且具有几何性,为造型中使用代数双曲B样条基奠定了更为完备的理论基础. 展开更多
关键词 嵌入节点算法 几乎严格全正性 系数变差 代数双曲B样条
下载PDF
诱导代数序乘法基与诱导右模序基
5
作者 韩德 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第3期293-300,共8页
通过 2个代数之间存在着的同态关系 ,借助一个代数具有Gr bnerGr bner基理论 ,而构造了另一个代数在一定条件下也具有Gr bner基理论 .同时还讨论了给定一个右R 模M ,并且M具有右Gr bner基理论 ,对于M的子模N ,N的什么性质是使右R 商模M/... 通过 2个代数之间存在着的同态关系 ,借助一个代数具有Gr bnerGr bner基理论 ,而构造了另一个代数在一定条件下也具有Gr bner基理论 .同时还讨论了给定一个右R 模M ,并且M具有右Gr bner基理论 ,对于M的子模N ,N的什么性质是使右R 商模M/N具有右Gr bner基理论的充分必要条件 . 展开更多
关键词 相邻2-项式 uniform元 有序 Groebner理论 K-代数 同态映射 诱导代数序乘法 诱导右模序
下载PDF
代数三角混合的样条曲线 被引量:10
6
作者 陈文喻 汪国昭 《计算机研究与发展》 EI CSCD 北大核心 2006年第4期679-687,共9页
B样条曲线能对多项式参数曲线提供有效的控制,但是它不能表示一些超越曲线,因此,很多文献提供了新的模型来构造曲线,但是这些模型要么只能表示低阶曲线,要么不能表示圆的渐开线和圆锥螺线.对此,在空间Ωk=span{cost,sint,tcost,tsint,1,... B样条曲线能对多项式参数曲线提供有效的控制,但是它不能表示一些超越曲线,因此,很多文献提供了新的模型来构造曲线,但是这些模型要么只能表示低阶曲线,要么不能表示圆的渐开线和圆锥螺线.对此,在空间Ωk=span{cost,sint,tcost,tsint,1,t,t2,…,tk-1}(k≥5)中构造一类曲线,称为节点序列T上的代数三角混合的k阶样条曲线(代数三角样条曲线),该类曲线具有很多与B样条曲线类似的性质,利用这些性质可以通过嵌入新节点对曲线进行逼近,并且可以精确表示圆锥螺线、圆的渐开线等超越曲线. 展开更多
关键词 代数三角样条函数 代数三角样条 代数三角样条 圆锥螺线 圆的渐开线
下载PDF
连续信息基(英文)
7
作者 陈学友 李庆国 曹永林 《模糊系统与数学》 CSCD 北大核心 2006年第3期59-63,共5页
D.Scott在20世纪60年代引入了domain理论,并给出了两种等价形式——信息系统和邻域系。在型论(typetheory)基础上,G.Sambin提出了形式拓扑(Formal topology)理论,并证明了一元形式拓扑与代数Scott domain等价,从而推出代数信息基的概念... D.Scott在20世纪60年代引入了domain理论,并给出了两种等价形式——信息系统和邻域系。在型论(typetheory)基础上,G.Sambin提出了形式拓扑(Formal topology)理论,并证明了一元形式拓扑与代数Scott domain等价,从而推出代数信息基的概念,同时作为信息系统与邻域系的推广。本文从信息基的观点出发,提出了连续信息基的概念,证明了它与连续Scott domain的等价性。 展开更多
关键词 SCOTT DOMAIN 代数信息 连续信息 型论
下载PDF
一维双曲守恒律方程的基于指数多项式逼近的间断Petrov-Galerkin方法 被引量:1
8
作者 孙雅洁 高巍 《应用数学进展》 2021年第12期4542-4553,共12页
本文利用间断Petrov-Galerkin方法求解双曲守恒律方程,使用非代数多项式有限元空间(指数多项式基函数)来构造逼近函数进行空间离散,用SSP Runge-Kutta方法进行时间离散,TVB型minmod限制器用来抑制间断解数值计算时的数值振荡。通过对典... 本文利用间断Petrov-Galerkin方法求解双曲守恒律方程,使用非代数多项式有限元空间(指数多项式基函数)来构造逼近函数进行空间离散,用SSP Runge-Kutta方法进行时间离散,TVB型minmod限制器用来抑制间断解数值计算时的数值振荡。通过对典型数值算例的计算,并与代数多项式间断Petrov-Galerkin方法的对比,结果显示本文的数值方法有良好的数值计算效果和数值稳定性。 展开更多
关键词 双曲守恒律 间断Petrov-Galerkin方法 代数多项式 指数多项式
下载PDF
Effect of Excited-state Substituent Constant on the UV Spectra of 1,4-disubstituted Benzenes 被引量:9
9
作者 陈冠凡 曹晨忠 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第4期366-370,447,共6页
A correlation equation between the UV absorption wavenumbers of 1,4-disubstituted benzenes and the excited-state substituent constant was obtained. For 80 sorts of 1,4- disubstituted benzenes, the correlation coeffici... A correlation equation between the UV absorption wavenumbers of 1,4-disubstituted benzenes and the excited-state substituent constant was obtained. For 80 sorts of 1,4- disubstituted benzenes, the correlation coefficient was 0.9805, and the standard deviation was only 672.27 cm^-1. The results imply that the excited-state substituent constant can be used productively for research on UV energy of 1,4-disubstituted benzenes. The present method provides a new avenue to study the UV absorption spectra of aromatic systems with the excited-state substituent constant, and it is helpful to understand the effect of substituent electrostatic effects on the chemical and physical properties of conjugated compounds with multiple substituents in excited state. 展开更多
关键词 Excited-state substituent constant 1 4-disubstituted benzene UV absorption wavenumber Interaction of substituent
下载PDF
Research on Thermodynamic Properties of Polybrominated Diphenylamine by Neural Network 被引量:19
10
作者 堵锡华 庄文昌 +1 位作者 史小琴 冯长君 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2015年第1期59-64,I0001,I0002,共8页
Based on the location of bromine substituents and conjugation matrix, a new substituent po- sition index ~X not only was defined, but also molecular shape indexes Km and electronega- tivity distance vectors Mm of diph... Based on the location of bromine substituents and conjugation matrix, a new substituent po- sition index ~X not only was defined, but also molecular shape indexes Km and electronega- tivity distance vectors Mm of diphenylamine and 209 kinds of polybrominated diphenylamine (PBDPA) molecules were calculated. Then the quantitative structure-property relationships (QSPR) among the thermodynamic properties of 210 organic pollutants and 0X, K3, M29, M36 were founded by Leaps-and-Bounds regression. Using the four structural parameters as input neurons of the artificial neural network, three satisfactory QSPR models with network structures of 4:21:1, 4:24:1, and 4:24:1 respectively, were achieved by the back-propagation algorithm. The total correlation coefficients R were 0.9999, 0.9997, and 0.9995 respectively and the standard errors S were 1.036, 1.469, and 1.510 respectively. The relative mean deviation between the predicted value and the experimental value of Sθ, AfHe and △fGθ- were 0.11%, 0.34% and 0.24% respectively, which indicated that the QSPR models had good stability and superior predictive ability. The results showed that there were good nonlinear correlations between the thermodynamic properties of PBDPAs and the four structural pa- rameters. Thus, it was concluded that the ANN models established by the new substituent position index were fully applicable to predict properties of PBDPAs. 展开更多
关键词 Polybrominated diphenylamine Neural networks Molecular shape index Elec-tronegativity distance vector Substituent position index Thermodynamic properties
下载PDF
高速高精度曲线重构与递推插补研究 被引量:5
11
作者 施群 游清宁 +1 位作者 黄宇亮 高胜林 《机械工程学报》 EI CAS CSCD 北大核心 2010年第3期193-198,共6页
为解决中高档计算机数控(Computer numerical control,CNC)中基于多项式基的Hermite样条曲线实时插补算法递推速度低且逼近精度较差的问题,文中利用指数函数e–t快速递推及收敛的优点,在代数指数混合空间构造新的样条曲线并给出基于该... 为解决中高档计算机数控(Computer numerical control,CNC)中基于多项式基的Hermite样条曲线实时插补算法递推速度低且逼近精度较差的问题,文中利用指数函数e–t快速递推及收敛的优点,在代数指数混合空间构造新的样条曲线并给出基于该曲线的递推插补算法。应用该算法进行的插补试验中,与Hermite曲线相比,新样条曲线的递推速度提高1.7~2.1倍,同时逼近精度提高一个数量级。结果表明基于新曲线的插补算法在提高轮廓加工轨迹精度的同时,也提高加工效率,满足中高档计算机数控中样条曲线的构造要求。 展开更多
关键词 计算机数控 高速高精度 样条插补 代数指数样条 快速递推
下载PDF
Lazard ss Elimination Process for Color Lie Superalgebras *
12
作者 周建华 《Journal of Southeast University(English Edition)》 EI CAS 1998年第2期140-143,共4页
A pattern of Lazard*ss elimination theorem for color Lie superalgebras is proved.
关键词 free color Lie supperalgebra BASE DERIVATION
下载PDF
The Structures of the AR Sequences of Tilted Algebras
13
作者 章璞 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第3期58-65,共8页
In this paper,We give the forms of AR sequences of a tilted algebra with terms all belonging to x(A_T),or all belonging to y(A_T).The sink maps of a tilted algebra which end at the indecompos able projective modules a... In this paper,We give the forms of AR sequences of a tilted algebra with terms all belonging to x(A_T),or all belonging to y(A_T).The sink maps of a tilted algebra which end at the indecompos able projective modules and the source maps of starting at the indecomposable injective modules are also obtained.These results together with the connecting sequecnes given in [3] determine the AR quiver of the tilted algcbra,morever,this can be done directly from the AR quiver of the correspond ing hereditary algebra. 展开更多
关键词 tilted algebra AR sequences
下载PDF
Substituent Effects on Reduction Potentials of Meta-substituted and Para-substituted Benzylideneanilines 被引量:1
14
作者 王琳艳 曹朝暾 曹晨忠 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第2期260-264,I0002,共6页
Effects of meta-substituent of 3,4'/4,3'/3,3'-substituted benzylideneanilines (XBAYs) on the electrochemical reduction potentials (E(Red)) were investigated, in which 49 samples of target compounds were synth... Effects of meta-substituent of 3,4'/4,3'/3,3'-substituted benzylideneanilines (XBAYs) on the electrochemical reduction potentials (E(Red)) were investigated, in which 49 samples of target compounds were synthesized, and their reduction potentials were measured by cyclic voltammetry. The substituent effects on the E(Red) of target compounds were analyzed and an optimality equation with four parameters (Hammett constant a of X, Hammett constant a of Y, excited-state substituent constant σexCC of X, and the substituent specific cross-interaction effect △σexCC2 between X and Y) was obtained. The results show that the factors affecting the E(Red) of 3,4'/4,31/3,3P-substituted XBAYs are different from those of 4,4'-substituted XBAYs. For 3,4'/4,3'/3,3'-substituted XBAYs, σ(X) and σ(Y) must be employed, and the contribution of △σexCC2 is important and not negligible. Compared with 4,4'-substituted XBAYs, X group contributes less to 3,4'/4,3'/3,3'-substituted XBAYs, while Y group contributes more to them. Additionally, it was observed that either para-substituted XBAYs or meta-substituted XBAYs, the substituent effects of X are larger than those of Y on the E(Red) of substituted XBAYs. 展开更多
关键词 3 4r/4 3'/3 3'-substituted benzylideneanilines Substituent effects Electro-chemical reduction potentials Cyclic voltammetry Excited-state substituent constant
下载PDF
Bombyx mori Pyridoxal Kinase cDNA Cloning and Enzymatic Characterization 被引量:1
15
作者 石瑞君 张剑韵 +1 位作者 江昌俊 黄龙全 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第8期683-690,共8页
Pyridoxal kinase (PLK) (EC 2.7.1.35) catalyzes the ATP-dependent phosphorylation of pyridoxal, generating pyridoxal-5'-phosphate (PLP), an important cofactor for many enzymatic reactions. Bombyx mori, similar t... Pyridoxal kinase (PLK) (EC 2.7.1.35) catalyzes the ATP-dependent phosphorylation of pyridoxal, generating pyridoxal-5'-phosphate (PLP), an important cofactor for many enzymatic reactions. Bombyx mori, similar to mammals, relies on a nutritional source of vitamin B6 to synthesize PLP. This article describes how a cDNA encoding PLK was cloned from Bombyx mori using the PCR method (GenBank accession number: DQ452397). The cDNA has an 894 bp open reading frame and encodes a protein of 298 amino acid residues with a molecular mass of 33.1 k.Da. The amino acid sequence shares 48.6% identity with that of human PLK, and it also contains signature conserved motifs of the PLK family. However, the protein is 10 or more amino acids shorter than the PLK from mammals and plants, and several amino acid residues conserved in the PLK from mammals and plants are changed in the protein. The cDNA cloned was expressed successfully in Escherichia coli using the T7 promoter/T7 RNA polymerase expression system, and the crude extracts containing the expressed product were found to have strong PLK enzymatic activity with a value of 30 nmol/min/mg, confirming that the cDNA encodes the functional PLK of Bombyx mori. This is the first identification of a gene encoding PLK in insects. 展开更多
关键词 pyridoxal kinase Bombyx mori (silkworm) pyridoxal-5'-phosphate (PLP) vitamin B6 metabolism genomic database
下载PDF
有限维线性赋范空间中的两个特征性质
16
作者 段雪梅 《邵阳学院学报(社会科学版)》 1998年第5期87-88,94,共3页
本文给出了线性赋范空间中线性泛函与“dimX<+∞”有关的两个特征性质。
关键词 线性赋范空间 irmX< +∞ 代数
下载PDF
New Matrix Loop Algebra and Its Application
17
作者 DONG Huan-He XU Yue-Cai 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第8期321-325,共5页
A new matrix Lie algebra and its corresponding Loop algebra are constructed firstly,as its application,the multi-component TC equation hierarchy is obtained,then by use of trace identity the Hamiltonian structure of t... A new matrix Lie algebra and its corresponding Loop algebra are constructed firstly,as its application,the multi-component TC equation hierarchy is obtained,then by use of trace identity the Hamiltonian structure of the above system is presented.Finally,the integrable couplings of the obtained system is worked out by the expanding matrix Loop algebra. 展开更多
关键词 matrix loop algebra Liouville integrable system Hamiltonian structure integrable couplings
下载PDF
A New Descent Algebra for Weyl Groups of Type An
18
作者 Tulay YAGMUR Himmet CAN 《Journal of Mathematics and System Science》 2016年第6期242-247,共6页
In this paper we define an equivalence relation on the set of all xj in order to form a basis for a new descent algebra of Weyl groups of type A,. By means of this, we construct a new commutative and semi-simple desce... In this paper we define an equivalence relation on the set of all xj in order to form a basis for a new descent algebra of Weyl groups of type A,. By means of this, we construct a new commutative and semi-simple descent algebra for Weyl groups of type An generated by equivalence classes arising from this equivalence relation. 展开更多
关键词 Weyl groups type An descent algebra.
下载PDF
Algebraic-Based Nonbinary LDPC Codes with Flexible Field Orders and Code Rates 被引量:3
19
作者 Hengzhou Xu Dan Feng +1 位作者 Cheng Sun Baoming Bai 《China Communications》 SCIE CSCD 2017年第4期111-119,共9页
In this paper, we study the rank of matrices over GF(2~p),and propose two construction methods for algebraic-based nonbinary LDPC codes from an existing LDPC code, referred to as the original code. By multiplying all ... In this paper, we study the rank of matrices over GF(2~p),and propose two construction methods for algebraic-based nonbinary LDPC codes from an existing LDPC code, referred to as the original code. By multiplying all elements of each column of the binary parity-check matrix H corresponding to the original code with the same nonzero element of any field, the first class of nonbinary LDPC codes with flexible field order is proposed. The second method is to replace the nonzero elements of some columns in H with different nonzero field elements in a given field, and then another class of nonbinary LDPC codes with various rates is obtained. Simulation results show that the proposed nonbinary LDPC codes perform well over the AWGN channel with the iterative decoding algorithms. 展开更多
关键词 nonbinary LDPC codes algebraic-based LDPC codes rank iterative algorithms
下载PDF
Super-KN Hierarchy and Its Super-Hamiltonian Structure 被引量:3
20
作者 TAO Si-Xing XIA Tie-Cheng SHI Hui 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第3期391-395,共5页
Based on the basis of the constructed Lie super algebra, the super-isospectral problem of KN hierarchy is considered. Under the frame of the zero curvature equation, the super-KN hierarchy is obtained. Furthermore, it... Based on the basis of the constructed Lie super algebra, the super-isospectral problem of KN hierarchy is considered. Under the frame of the zero curvature equation, the super-KN hierarchy is obtained. Furthermore, its super-Hamiltonian structure is presented by using super-trace identity and it has super-bi-Hamiltonian structure. 展开更多
关键词 Lie super algebra super-trace identity super-integrable system super-Hamiltonian structure
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部