期刊文献+
共找到1,142篇文章
< 1 2 58 >
每页显示 20 50 100
A self-cited pixel summation based image encryption algorithm 被引量:1
1
作者 Guo-Dong Ye Xiao-Ling Huang +1 位作者 Leo Yu Zhang Zheng-Xia Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第1期131-138,共8页
In this paper, a novel image encryption algorithm is presented based on self-cited pixel summation. With the classical mechanism of permutation plus diffusion, a pixel summation of the plain image is employed to make ... In this paper, a novel image encryption algorithm is presented based on self-cited pixel summation. With the classical mechanism of permutation plus diffusion, a pixel summation of the plain image is employed to make a gravity influence on the pixel positions in the permutation stage. Then, for each pixel in every step of the diffusion stage, the pixel summation calculated from the permuted image is updated. The values from a chaotic sequence generated by an intertwining logistic map are selected by this summation. Consequently, the keystreams generated in both stages are dependent on both the plain image and the permuted image. Because of the sensitivity of the chaotic map to its initial conditions and the plain-imagedependent keystreams, any tiny change in the secret key or the plain image would lead to a significantly different cipher image. As a result, the proposed encryption algorithm is immune to the known plaintext attack(KPA) and the chosen plaintext attack(CPA). Moreover, experimental simulations and security analyses show that the proposed permutationdiffusion encryption scheme can achieve a satisfactory level of security. 展开更多
关键词 pixel summation image encryption algorithm intertwining logistic map GRAVITY SECURITY
原文传递
Application of Gaussian Beam Summation Migration in Reflected In-seam Wave Imaging 被引量:1
2
作者 HAN Jianguang LÜQingtian +2 位作者 ZHANG Zhiheng YANG Shun WANG Shuo 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第1期276-284,共9页
The geological conditions for coal mining in China are complex,with various structural issues such as faults and collapsed columns seriously compromising the safety of coal mine production.In-seam wave exploration is ... The geological conditions for coal mining in China are complex,with various structural issues such as faults and collapsed columns seriously compromising the safety of coal mine production.In-seam wave exploration is an effective technique for acquiring detailed information on geological structures in coal seam working faces.However,the existing reflected in-seam wave imaging technique can no longer meet the exploration precision requirements,making it imperative to develop a new reflected in-seam wave imaging technique.This study applies the Gaussian beam summation(GBS)migration method to imaging coal seams'reflected in-seam wave data.Firstly,with regard to the characteristics of the reflected in-seam wave data,methods such as wavefield removal and enveloped superposition are employed for the corresponding wavefield separation,wave train compression and other processing of reflected in-seam waves.Thereafter,imaging is performed using the GBS migration technique.The feasibility and effectiveness of the proposed method for reflected in-seam wave imaging are validated by conducting GBS migration tests on 3D coal-seam fault models with different dip angles and throws.By applying the method to reflected in-seam wave data for an actual coal seam working face,accurate imaging of a fault structure is obtained,thereby validating its practicality. 展开更多
关键词 reflected in-seam wave Gaussian beam summation migration numerical tests fault
在线阅读 下载PDF
Loudness Summation and Weightings for Loudness and Environmental Noise Assessment 被引量:1
3
作者 Juhani Parmanen 《Open Journal of Acoustics》 2014年第3期105-114,共10页
A stationary loudness model has been built up on the basis of the former ISO 226: 1987 concerning equal-loudness-level contours. The loudness and loudness level expressions derived in the study include the same parame... A stationary loudness model has been built up on the basis of the former ISO 226: 1987 concerning equal-loudness-level contours. The loudness and loudness level expressions derived in the study include the same parameters as used when determining the equal-loudness-level contours of the former ISO standard. However, as an additional main idea, a loudness summation rule has been proposed in the study. Moreover, the loudness expressions have been normalised to give the same values for people who have a similar sense of hearing. It has also been found that the loudness expressions include basically two different weightings. The first weighting is a conservative frequency weighting in the domain of sound pressure level, and the second weighting consists of coefficients applied to the weighted sound pressure levels. The latter have the greatest effect on the very low-frequency range. Finally, the paper includes a new way to use the A-weighting which takes into account the compressed character of the equal-loudness-level contours at the low frequency range. This method remarkably transforms the character of the A-weighting as a measure for low-frequency environmental noise. 展开更多
关键词 LOUDNESS LOUDNESS LEVEL LOUDNESS summation FREQUENCY Weightings A-Weighting LOW FREQUENCY Noise
暂未订购
On a Kind of Series Summation Utilizing C-Numbers 被引量:2
4
作者 Leetsch C.HSU Xinrong MA 《Journal of Mathematical Research with Applications》 CSCD 2014年第1期1-11,共11页
This paper provides a pair of summation formulas for a kind of combinatorial series involvingak+b m as a factor of the summand. The construction of formulas is based on a certain series transformation formula [2, 7, ... This paper provides a pair of summation formulas for a kind of combinatorial series involvingak+b m as a factor of the summand. The construction of formulas is based on a certain series transformation formula [2, 7, 9] and by making use of the C-numbers [3]. Various consequences and examples including several remarkable classic identities are presented to illustrate some applications of the formulas obtained. 展开更多
关键词 combinatorial series summation formula diference operator generalized Stirling number C-number.
原文传递
Estimates of three classical summations on the spaces F_p^(α,q)(R^n)(0 < p ≤ 1)
5
作者 GAO Gui-lian ZHONG Yong 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2014年第3期329-338,共10页
We obtain the boundedness on Fp^α,q(R^n)for the Poisson summation and Gauss summation. Their maximal operators are proved to be bounded from Fp^α,q(R^n)to L∞(R^n)For the maximal operator of the Bochner-Riesz ... We obtain the boundedness on Fp^α,q(R^n)for the Poisson summation and Gauss summation. Their maximal operators are proved to be bounded from Fp^α,q(R^n)to L∞(R^n)For the maximal operator of the Bochner-Riesz summation, we prove that it is bounded from Fp^α,q(R^n)to L n-pα/pn,(0〈p≤ 1)∞(R^n). 展开更多
关键词 Poisson summation Gauss summation Bochner-Riesz summation Triebel-Lizorkin space.
在线阅读 下载PDF
ULAM-HYERS-RASSIAS STABILITY AND EXISTENCE OF SOLUTIONS TO NONLINEAR FRACTIONAL DIFFERENCE EQUATIONS WITH MULTIPOINT SUMMATION BOUNDARY CONDITION
6
作者 Syed Sabyel HAIDER Mujeeb Ur REHMAN 《Acta Mathematica Scientia》 SCIE CSCD 2020年第2期589-602,共14页
The purpose of this study is to acquire some conditions that reveal existence and stability for solutions to a class of difference equations with non-integer orderμ∈(1,2].The required conditions are obtained by appl... The purpose of this study is to acquire some conditions that reveal existence and stability for solutions to a class of difference equations with non-integer orderμ∈(1,2].The required conditions are obtained by applying the technique of contraction principle for uniqueness and Schauder’s fixed point theorem for existence.Also,we establish some conditions under which the solution of the considered class of difference equations is generalized Ulam-Hyers-Rassias stable.Example for the illustration of results is given. 展开更多
关键词 Fractional difference equation Green's function existence and uniqueness Ulam-Hyers-Rassias stability summation boundary condition
在线阅读 下载PDF
On the best convergence order of a new class of triangular summation operators
7
作者 孟佳娜 赵连霞 《Journal of Shanghai University(English Edition)》 CAS 2006年第5期399-401,共3页
In this paper, a new class of triangular summation operators based on the equidistant nodes was constructed. It is proved that this class of operators converges uniformly to arbitrary continuous fimctions with the per... In this paper, a new class of triangular summation operators based on the equidistant nodes was constructed. It is proved that this class of operators converges uniformly to arbitrary continuous fimctions with the period 2π on the whole axis, Fttrthermore, the best approximation order and the highest convergence order are obtained. In contrast to certain operators constructed by Bernstein and Kis in the previous works, the convergence properties of the new operator constructed in this paper are superior. 展开更多
关键词 triangular summation operator uniform convergence the best approxdmation order the highest convergence order
在线阅读 下载PDF
The Non-countable Summation Type Hahn-Schur Theorems
8
作者 LUETong-fu HUJian-hua CHOMin-hyung 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2005年第2期137-140,共4页
The classical countable summation type Hahn-Schur theorem is a famous result in summation theory and measure theory. An interesting problem is whether the theorem can be generalized to non-countable summation case? In... The classical countable summation type Hahn-Schur theorem is a famous result in summation theory and measure theory. An interesting problem is whether the theorem can be generalized to non-countable summation case? In this paper, we show that the answer is true. 展开更多
关键词 rton-countable set summation Abelian topological group Hahn-Schur theorem
在线阅读 下载PDF
Summation of Reciprocals Related to Square of Products of Fibonacci Numbers
9
作者 席高文 王淑玉 《Chinese Quarterly Journal of Mathematics》 CSCD 2009年第3期400-406,共7页
By applying the method of on summation by parts,the purpose of this paper is to give several reciprocal summations related to squares of products of the Fibonacci numbers.
关键词 Fibonacci numbers summation SQUARE reciprocal
在线阅读 下载PDF
SUMMATION OF TRIGONOMETRIC SERIES BY FOURIER TRANSFORMS
10
作者 钱伟长 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第5期385-397,共13页
This paper gives the theorems concerning the summation of trigonometric series with the help of Fourier transforms. By means of the known results of Fourier transforms, many difficult and complex problems of summation... This paper gives the theorems concerning the summation of trigonometric series with the help of Fourier transforms. By means of the known results of Fourier transforms, many difficult and complex problems of summation of trigonometric series can be solved. This method is a comparatively unusual way to find the summation of trigonometric series, and has been used to establish the comprehensive table of summation of trigonometric series. In this table 10 thousand scries arc given, and most of them are new. 展开更多
关键词 exp summation OF TRIGONOMETRIC SERIES BY FOURIER TRANSFORMS
在线阅读 下载PDF
On a New Family of Trigonometric Summation Polynomials of Bernstein Type
11
作者 袁学刚 何甲兴 《Northeastern Mathematical Journal》 CSCD 2006年第1期99-104,共6页
A new family of trigonometric summation polynomials, Gn,r(f; θ), of Bernstein type is constructed. In contrast to other trigonometric summation polynomials, the convergence properties of the new polynomials are sup... A new family of trigonometric summation polynomials, Gn,r(f; θ), of Bernstein type is constructed. In contrast to other trigonometric summation polynomials, the convergence properties of the new polynomials are superior to others. It is proved that Gn,r(f; θ) converges to arbitrary continuous functions with period 2π uniformly on (-∞ +∞) as n→ ∞. In particular, Gn,r(f; θ) has the best convergence order, and its saturation order is 1/n^2r+4. 展开更多
关键词 trigonometric summation polynomial uniform convergence the best convergence order saturation order
在线阅读 下载PDF
Discrete Vector Calculus and Helmholtz Hodge Decomposition for Classical Finite Difference Summation by Parts Operators
12
作者 Hendrik Ranocha Katharina Ostaszewski Philip Heinisch 《Communications on Applied Mathematics and Computation》 2020年第4期581-611,共31页
In this article,discrete variants of several results from vector calculus are studied for clas-sical finite difference summation by parts operators in two and three space dimensions.It is shown that existence theorems... In this article,discrete variants of several results from vector calculus are studied for clas-sical finite difference summation by parts operators in two and three space dimensions.It is shown that existence theorems for scalar/vector potentials of irrotational/solenoidal vector fields cannot hold discretely because of grid oscillations,which are characterised explicitly.This results in a non-vanishing remainder associated with grid oscillations in the discrete Helmholtz Hodge decomposition.Nevertheless,iterative numerical methods based on an interpretation of the Helmholtz Hodge decomposition via orthogonal projections are pro-posed and applied successfully.In numerical experiments,the discrete remainder vanishes and the potentials converge with the same order of accuracy as usual in other first-order partial differential equations.Motivated by the successful application of the Helmholtz Hodge decomposition in theoretical plasma physics,applications to the discrete analysis of magnetohydrodynamic(MHD)wave modes are presented and discussed. 展开更多
关键词 summation by parts Vector calculus Helmholtz Hodge decomposition Mimetic properties Wave mode analysis
在线阅读 下载PDF
OPTIMAL SUMMATION INTERVAL AND NONEXISTENCE OF POSITIVE SOLUTIONS TO A DISCRETE SYSTEM
13
作者 陈晓莉 郑雄军 《Acta Mathematica Scientia》 SCIE CSCD 2014年第6期1720-1730,共11页
In this paper, we are concerned with properties of positive solutions of the following Euler-Lagrange system associated with the weighted Hardy-Littlewood-Sobolev inequality in discrete form{uj =∑ k ∈Zn vk^q/(1 + ... In this paper, we are concerned with properties of positive solutions of the following Euler-Lagrange system associated with the weighted Hardy-Littlewood-Sobolev inequality in discrete form{uj =∑ k ∈Zn vk^q/(1 + |j|)^α(1 + |k- j|)^λ(1 + |k|)^β,(0.1)vj =∑ k ∈Zn uk^p/(1 + |j|)^β(1 + |k- j|)^λ(1 + |k|)^α,where u, v 〉 0, 1 〈 p, q 〈 ∞, 0 〈 λ 〈 n, 0 ≤α + β≤ n- λ,1/p+1〈λ+α/n and 1/p+1+1/q+1≤λ+α+β/n:=λ^-/n. We first show that positive solutions of(0.1) have the optimal summation interval under assumptions that u ∈ l^p+1(Z^n) and v ∈ l^q+1(Z^n). Then we show that problem(0.1) has no positive solution if 0 〈λˉ pq ≤ 1 or pq 〉 1 and max{(n-λ^-)(q+1)/pq-1,(n-λ^-)(p+1)/pq-1} ≥λ^-. 展开更多
关键词 summation optimal interval nonexistence weighted Hardy-Littlewood-Sobolev inequality
在线阅读 下载PDF
The Proof and Application of a Summation Formula
14
作者 Yongmin Wang 《Advances in Pure Mathematics》 2022年第9期541-559,共19页
In this paper, some conclusions related to the prime number theorem, such as the Mertens formula are improved by the improved Abelian summation formula, and some problems such as “Dirichlet” function and “W(n)” fu... In this paper, some conclusions related to the prime number theorem, such as the Mertens formula are improved by the improved Abelian summation formula, and some problems such as “Dirichlet” function and “W(n)” function are studied. 展开更多
关键词 Abel summation Formula Mertens a Prime Number Theorem Dirichlet Function Conclusion Improvement
在线阅读 下载PDF
On the Implementation of Exponential B-Splines by Poisson Summation Formula
15
作者 Sinuk Kang 《Journal of Applied Mathematics and Physics》 2016年第4期637-640,共4页
Polynomial splines have played an important role in image processing, medical imaging and wavelet theory. Exponential splines which are of more general concept have been recently investigated.We focus on cardinal expo... Polynomial splines have played an important role in image processing, medical imaging and wavelet theory. Exponential splines which are of more general concept have been recently investigated.We focus on cardinal exponential splines and develop a method to implement the exponential B-splines which form a Riesz basis of the space of cardinal exponential splines with finite energy. 展开更多
关键词 Exponential Splines B-SPLINES Poisson summation Formula
在线阅读 下载PDF
草原公路长时程驾驶条件下信息量对驾驶员脑电信号的影响 被引量:1
16
作者 戚春华 苏杭 +1 位作者 李航天 季天行 《公路交通科技》 北大核心 2025年第4期1-7,130,共8页
【目标】为优化草原公路交通工程设施设置,规避长时间单调行车环境带来的行车风险,对不同信息量水平的交通标志在时间累积效应下对驾驶员脑电信号产生的影响规律进行探究。【方法】考虑到草原地区地貌、公路线形及路侧景观特殊,选取具... 【目标】为优化草原公路交通工程设施设置,规避长时间单调行车环境带来的行车风险,对不同信息量水平的交通标志在时间累积效应下对驾驶员脑电信号产生的影响规律进行探究。【方法】考虑到草原地区地貌、公路线形及路侧景观特殊,选取具有典型特征的草原公路路段进行150 min的实驾试验。通过连续采集驾驶过程中10名被试的脑电信号,并选取两个反应驾驶员精神状态和认知过程的敏感指标,对其进行整体趋势变化观察和前后两程组间不同信息量等级的差异分析,并结合时间、信息量进行双因素方差分析。【结果】交通标志信息量处于20~30 bits负荷水平时,驾驶员精神状态较好且对信息感知判断和决策能力受驾驶时间影响较小,为建议信息量等级,范围以外都会导致时间累积效应下疲劳累积加速;双因素方差分析中信息量变化对beta波作用主效应显著,时间累积效应在(alpha+theta)/beta指标上得以反映,而驾驶时间与信息负荷水平交互作用显著。【结论】信息量不足或过载在时间累积效应下负面影响严重威胁驾驶安全,故针对草原特殊长距离行车环境,交通工程设施设计信息量建议衡量设施设置位置不同及驾驶员行车时间的增长进行进一步细致优化。 展开更多
关键词 交通工程 交通标志信息量 时间累积效应 脑电信号 草原公路
原文传递
基于GASF与MSCAM-DenseNet的小样本齿轮故障诊断方法 被引量:1
17
作者 史丽晨 张鹏 +1 位作者 王海涛 周星宇 《计算机集成制造系统》 北大核心 2025年第8期3033-3045,共13页
针对小样本条件下所得样本不足,特征未能有效提取导致诊断精度下降的问题,提出一种GASF与MSCAM-DenseNet相结合的小样本齿轮故障诊断方法。首先,运用格拉姆角和域(GASF)将多源振动信号变换为二维特征,采用二维离散小波变换(2D-DWT)重构... 针对小样本条件下所得样本不足,特征未能有效提取导致诊断精度下降的问题,提出一种GASF与MSCAM-DenseNet相结合的小样本齿轮故障诊断方法。首先,运用格拉姆角和域(GASF)将多源振动信号变换为二维特征,采用二维离散小波变换(2D-DWT)重构多源特征。其次,由于一般的密集连接卷积网络(DenseNet)不具备识别多尺度特征的能力,因而在DenseNet中引入多尺度通道注意力机制(MSCAM),提出一种改进网络模型,即MSCAM-DenseNet。最后,以重构后的GASF作为MSCAM-DenseNet的输入,待特征识别完成后,由网络分类器完成故障特征分类。采用实验室行星齿轮数据集和东南大学齿轮箱数据集对所提模型验证,并与其他诊断模型进行对比。实验结果证明,所提方法在小样本、变工况条件下具有较高的故障识别准确率,较强的泛化能力和抗噪能力。 展开更多
关键词 齿轮 小样本故障诊断 格拉姆角和域 二维离散小波变换 多尺度通道注意力机制
在线阅读 下载PDF
面向国产RISC-V芯片的高效高精度求和与点积算法
18
作者 李骥 邱琪 +4 位作者 张翔 肖调杰 孟祥飞 龚春叶 冯超超 《小型微型计算机系统》 北大核心 2025年第11期2798-2806,共9页
RISC-V作为一种新兴的开源精简指令集架构,是后摩尔时代处理器技术发展与创新的关键之一.浮点求和与点积运算是数值运算的基础组成部分,在众多领域应用广泛.目前RISC-V架构尚未适配兼具高精度和高效率的求和与点积运算算法,这是因为现... RISC-V作为一种新兴的开源精简指令集架构,是后摩尔时代处理器技术发展与创新的关键之一.浮点求和与点积运算是数值运算的基础组成部分,在众多领域应用广泛.目前RISC-V架构尚未适配兼具高精度和高效率的求和与点积运算算法,这是因为现有优化方案难以良好地平衡运算精度和效率,要么侧重于低精度算法效率,要么通过牺牲效率实现高精度运算.本文利用RVV(RISC-V Vector instruction set extension,RVV)矢量扩展指令,设计并实现了一种基于无误差变换技术的高效、高精度求和与点积算法.首先避免使用规约指令以防止运算精度降低,实现并优化两类运算基于RVV的向量化算法;其次根据算法中的数据依赖关系,对寄存器配置参数进行优化.最后针对算法核心步骤进行汇编优化,增加指令级并行度,提高流水线利用率.实验结果表明,与两类运算操作的原始算法相比,优化后的算法运算效率分别提高了4.4和4.2倍.优化后的算法与多精度库MPFR中的四精度算法有相同精度,但其运算效率明显优于后者,其计算速度与OpenBLAS的双精度计算速度相当. 展开更多
关键词 RISC-V 点积 求和 无误差变换 高精度 向量化
在线阅读 下载PDF
与p级数余项幂次相关的级数之和
19
作者 雷冬霞 黄永忠 《大学数学》 2025年第5期77-83,共7页
利用二重和式的换序及Abel分部求和公式,得到与p级数余项的幂次相关的一类级数的求和,并给出几个应用例子.
关键词 二重和式 换序 Abel分部求和公式 BERNOULLI数
在线阅读 下载PDF
基于两次量子搜索的K子集和问题求解
20
作者 叶天语 吴恒 甘志刚 《通信学报》 北大核心 2025年第7期182-190,共9页
针对K子集和问题,提出了一种基于两次量子搜索的高效量子算法。第一次量子搜索通过变异Grover算子生成包含所有元素个数为K的子集的量子叠加态;具体地,首先通过Oracle算子进行相位翻转标记所有含K个元素的子集,然后通过扩散算子放大标... 针对K子集和问题,提出了一种基于两次量子搜索的高效量子算法。第一次量子搜索通过变异Grover算子生成包含所有元素个数为K的子集的量子叠加态;具体地,首先通过Oracle算子进行相位翻转标记所有含K个元素的子集,然后通过扩散算子放大标记的目标子集的概率幅值。第二次量子搜索则通过另一个变异Grover算子从所有元素个数为K的子集中找到K个元素和等于目标值的子集;具体地,首先通过特定的和校验Oracle算子标记所有的元素和等于目标值且只含K个元素的子集,然后通过扩散算子放大标记子集的概率幅值。仿真实验结果表明,所提方法准确率大于或等于89%,较现有方法准确率更高。 展开更多
关键词 K子集和问题 GROVER量子搜索算法 布尔可满足性问题 量子线路
在线阅读 下载PDF
上一页 1 2 58 下一页 到第
使用帮助 返回顶部