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基于新离散公式和OpenMP优化的有限差分声波数值模拟 被引量:1
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作者 郑如秋 王波涛 +1 位作者 冯永照 余卫江 《世界地质》 CAS 2020年第4期896-904,共9页
有限差分法算法是声波数值模拟算法中最广泛的数值计算方法。该方法具有计算速度快、占用内存相对较小、易于编程实现及模拟精度高等优点。规则网格下的有限差分算法相比于近年来提出的新的有限差分算法计算效率最高,消耗内存最少。然而... 有限差分法算法是声波数值模拟算法中最广泛的数值计算方法。该方法具有计算速度快、占用内存相对较小、易于编程实现及模拟精度高等优点。规则网格下的有限差分算法相比于近年来提出的新的有限差分算法计算效率最高,消耗内存最少。然而,引入PML边界,导致常规网格的有限差分离散公式复杂,计算过程需要对计算区域和边界区域进行判断,导致计算效率低。针对这个问题,笔者新推导的离散公式,形式简单,整个模拟区域计算代码一致,可以很好地解决这个问题。OpenMP并行算法,语言简洁和可移植性高,通过结合OpenMP并行算法,对模拟算法进一步优化,可以较大提高数值模拟的计算效率。 展开更多
关键词 有限差分 规则网格 离散公式 OpenMP并行算法 计算效率
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基于正序与离散辛普生积分均值公式的三相瞬时谐波检测算法
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作者 刘传林 侯宁宁 张迎峰 《长沙电力学院学报(自然科学版)》 2005年第3期5-9,共5页
在三相三线制中,三相谐波瞬时无功功率理论ip-iq运算变换的正序有功电流i+p和无功电流i+q只含3k(k为整数)次谐波.根据这一特征,设计应用离散辛普生积分公式计算均值的算法提取正序基波电流直流分量,通过反变换得到正序基波电流分量,再... 在三相三线制中,三相谐波瞬时无功功率理论ip-iq运算变换的正序有功电流i+p和无功电流i+q只含3k(k为整数)次谐波.根据这一特征,设计应用离散辛普生积分公式计算均值的算法提取正序基波电流直流分量,通过反变换得到正序基波电流分量,再从该电流分量重构得到电流谐波分量.该算法可以减少谐波检测过程的计算量,易于实现数字运算.理论分析和MATLAB仿真表明,应用该算法的信号检测有较快的动态响应特性,能实现对三相电路谐波电流的检测. 展开更多
关键词 三相瞬时谐波检测 ip-iq运算方式 离散辛普生积分公式均值算法 MATLAB仿真实验
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交流信号采样离散计算公式 被引量:4
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作者 赵永胜 丛培建 赵正聪 《电子技术应用》 北大核心 2007年第10期75-77,共3页
提出了交流信号的电压有效值、电流有效值、有功功率的离散计算公式,并给出了严格的数学证明,分别得出了有效值和有功功率计算中每周波最少采样点数。
关键词 离散计算公式 每周波最少采样点数
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Lipschitz曲线上Besov-Triebel-Lizorkin空间的嵌入定理(英文)
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作者 邓东皋 颜立新 《数学进展》 CSCD 北大核心 2003年第3期303-310,共8页
本文用离散的Calderón型再生公式。证明了Lipschitz曲线上Beasov空间与Triebel-Lizorkin空间的嵌入定理。
关键词 Lipschitz曲线 Besov-Triebel-Lizorkin空间 嵌入定理 离散Calderón型再生公式 复平面
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二值图像Legendre矩快速算法
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作者 朱斌 董剑 +2 位作者 舒华忠 姜璐 罗立民 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2003年第1期90-93,共4页
提出一种有效的计算二值图像Legendre矩的方法 .首先使用Yang 离散格林公式将二值图像矩计算中区域内求和转换为沿区域边界求和 ;然后提取该图像的边界点 ;再利用Shu提出的公式计算出边界点的Legendre多项式的叠加值 .经过这 3步后 ,二... 提出一种有效的计算二值图像Legendre矩的方法 .首先使用Yang 离散格林公式将二值图像矩计算中区域内求和转换为沿区域边界求和 ;然后提取该图像的边界点 ;再利用Shu提出的公式计算出边界点的Legendre多项式的叠加值 .经过这 3步后 ,二维Legendre矩计算转化为一维Legendre矩计算 ,从而有效地减少计算复杂度 .介绍了用Hatamian滤波器计算一维Legendre矩的方法 . 展开更多
关键词 二值图像 快速算法 LEGENDRE矩 离散格林公式 轮廓跟踪 模式识别 图像处理
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工业反应炉中气体流动压力的数值模型(英文)
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作者 宋昌浩 吴声昌 《工程数学学报》 CSCD 北大核心 2004年第5期803-806,共4页
本文构造了工业反应炉中气体流动压力的离散化方程,同时证明了方程解的存在性和唯一性。
关键词 离散Green公式 Ergun定律 有限元方法
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一类随机差分方程解的稳定性分析
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作者 葛玲玲 廖新元 +1 位作者 陈会利 鲁银霞 《数学理论与应用》 2017年第2期24-31,共8页
研究一类线性随机差分方程解的渐进性态,运用离散的It公式、随机差分比较定理,得到该方程解的随机稳定与不稳定性的充分条件.最后,数值仿真说明所得结论的正确性.
关键词 随机差分方程 离散的Ito公式 解的随机稳定性
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无功功率算法研究
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作者 蒋淦华 吴志鹏 陈琼 《自动化应用》 2015年第10期109-111,共3页
由于目前测量无功功率的仪器功能单一和精度不高,故在研制仪表校验台多功能表的基础上,详细分析三相交流信号在五种接线方式(三相四线、三相三线、三元90°、二元90°、二元60°)下的向量图,推导出离散化公式。通过多功能... 由于目前测量无功功率的仪器功能单一和精度不高,故在研制仪表校验台多功能表的基础上,详细分析三相交流信号在五种接线方式(三相四线、三相三线、三元90°、二元90°、二元60°)下的向量图,推导出离散化公式。通过多功能表对三相交流信号进行采样,把采样值代入对应的离散化公式中,计算出无功功率。实验数据表明:五种接线方式下的总无功功率测量精度均在0.1%以内。 展开更多
关键词 无功功率 多功能表 五种接线方式 向量图 离散公式
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Unknown parameter’s variance-covariance propagation and calculation in generalized nonlinear least squares problem 被引量:6
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作者 陶华学 郭金运 《Journal of Coal Science & Engineering(China)》 2005年第1期52-55,共4页
The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. Th... The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. The unknown parameter’s vari- ance-covariance propagation formula, considering the two-power terms, was concluded used to evaluate the accuracy of unknown parameter estimators in the generalized nonlinear least squares problem. It is a new variance-covariance formula and opens up a new way to evaluate the accuracy when processing data which have the multi-source, multi-dimensional, multi-type, multi-time-state, different accuracy and nonlinearity. 展开更多
关键词 generalized nonlinear least squares problem unknown parameter vari- ance-covariance propagation
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Scaling Argument of Anisotropic Random Walk
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作者 XUBing-Zhen JINGuo-Jun WANGFei-Feng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3期449-454,共6页
In this paper, we analytically discuss the scaling properties of the average square end-to-end distance < R-2 > for anisotropic random walk in D-dimensional space (D >= 2), and the returning probability P-n(r... In this paper, we analytically discuss the scaling properties of the average square end-to-end distance < R-2 > for anisotropic random walk in D-dimensional space (D >= 2), and the returning probability P-n(r(0)) for the walker into a certain neighborhood of the origin. We will not only give the calculating formula for < R-2 > and P-n(r(0)), but also point out that if there is a symmetric axis for the distribution of the probability density of a single step displacement, we always obtain < R-perpendicular to n(2) > similar to n, where perpendicular to refers to the projections of the displacement perpendicular to each symmetric axes of the walk; in D-dimensional space with D symmetric axes perpendicular to each other, we always have < R-n(2)> similar to n and the random walk will be like a purely random motion; if the number of inter-perpendicular symmetric axis is smaller than < R-n(2)> similar to n(2) the dimensions of the space, we must have n for very large n and the walk will be like a ballistic motion. It is worth while to point out that unlike the isotropic random walk in one and two dimensions, which is certain to return into the neighborhood of the origin, generally there is only a nonzero probability for the anisotropic random walker in two dimensions to return to the neighborhood. 展开更多
关键词 SCALING anisotropic random walk average square end-to-end distance returning probability
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拟线性抛物组具有并行本性的无条件稳定与收敛的差分方法 被引量:3
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作者 周毓麟 沈隆钧 袁光伟 《中国科学(A辑)》 CSCD 北大核心 2003年第4期310-324,共15页
在不作启示性假定下,研究了拟线性抛物型方程组初边值问题的一类具有并行本性的差分格式,利用不动点原理、离散内插公式和先验估计方法,证明了所构造的具有并行本性差分格式解的存在性、惟一性和在离散W_2^(2,1)范数下的无条件稳定性,... 在不作启示性假定下,研究了拟线性抛物型方程组初边值问题的一类具有并行本性的差分格式,利用不动点原理、离散内插公式和先验估计方法,证明了所构造的具有并行本性差分格式解的存在性、惟一性和在离散W_2^(2,1)范数下的无条件稳定性,并证明了一大类具有并行本性的差分格式的解收敛到原始拟线性抛物问题的惟一广义解。 展开更多
关键词 拟线性抛物型方程组 初边值问题 差分格式 并行本性 收敛性 稳定性 不动点原理 离散内插公式
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Queue Size Distribution of Geo/G/1 Queue Under the Min(N,D)-Policy 被引量:14
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作者 GU Jianxiong WEI Yingyuan +1 位作者 TANG Yinghui YU Miaomiao 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2016年第3期752-771,共20页
This paper considers a discrete-time Geo/G/1 queue under the Min(N, D)-policy in which the idle server resumes its service if either N customers accumulate in the system or the total backlog of the service times of ... This paper considers a discrete-time Geo/G/1 queue under the Min(N, D)-policy in which the idle server resumes its service if either N customers accumulate in the system or the total backlog of the service times of the waiting customers exceeds D, whichever occurs first (Min(N, D)-policy). By using renewal process theory and total probability decomposition technique, the authors study the transient and equilibrium properties of the queue length from the beginning of the arbitrary initial state, and obtain both the recursive expression of the z-transformation of tile transient queue length distribution and the recursive formula for calculating the steady state queue length at arbitrary time epoch n+. Meanwhile, the authors obtain the explicit expressions of the additional queue length distribution, l^trthermore, the important relations between the steady state queue length distributions at different time epochs n , n and n+ are also reported. Finally, the authors give numerical examples to illustrate the effect of system parameters on the steady state queue length distribution, and also show from numerical results that the expressions of the steady state queue length distribution is important in the system capacity design. 展开更多
关键词 Min(N D)-policy discrete-time queue queue length distribution system capacity opti mum design total probability decomposition technique z-transform.
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The spatial scaling effect of the discrete-canopy effective leaf area index retrieved by remote sensing 被引量:5
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作者 FAN WenJie GAI YingYing +1 位作者 XU XiRu YAN BinYan 《Science China Earth Sciences》 SCIE EI CAS 2013年第9期1548-1554,共7页
The leaf area index(LAI) is a critical biophysical variable that describes canopy geometric structures and growth conditions.It is also an important input parameter for climate,energy and carbon cycle models.The scali... The leaf area index(LAI) is a critical biophysical variable that describes canopy geometric structures and growth conditions.It is also an important input parameter for climate,energy and carbon cycle models.The scaling effect of the LAI has always been of concern.Considering the effects of the clumping indices on the BRDF models of discrete canopies,an effective LAI is defined.The effective LAI has the same function of describing the leaf density as does the traditional LAI.Therefore,our study was based on the effective LAI.The spatial scaling effect of discrete canopies significantly differed from that of continuous canopies.Based on the directional second-derivative method of effective LAI retrieval,the mechanism responsible for the spatial scaling effect of the discrete-canopy LAI is discussed and a scaling transformation formula for the effective LAI is suggested in this paper.Theoretical analysis shows that the mean values of effective LAIs retrieved from high-resolution pixels were always equal to or larger than the effective LAIs retrieved from corresponding coarse-resolution pixels.Both the conclusions and the scaling transformation formula were validated with airborne hyperspectral remote sensing imagery obtained in Huailai County,Zhangjiakou,Hebei Province,China.The scaling transformation formula agreed well with the effective LAI retrieved from hyperspectral remote sensing imagery. 展开更多
关键词 The spatial scaling effect of the discrete-canopy effective leaf area index retrieved by remote sensing
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Addition Formulae of Discrete KP,q-KP and Two-Component BKP Systems
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作者 高旭 李传忠 贺劲松 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第4期410-422,共13页
In this paper,we construct the addition formulae for several integrable hierarchies,including the discrete KP,the q-deformed KP,the two-component BKP and the D type Drinfeld–Sokolov hierarchies.With the help of the H... In this paper,we construct the addition formulae for several integrable hierarchies,including the discrete KP,the q-deformed KP,the two-component BKP and the D type Drinfeld–Sokolov hierarchies.With the help of the Hirota bilinear equations and τ functions of different kinds of KP hierarchies,we prove that these addition formulae are equivalent to these hierarchies.These studies show that the addition formula in the research of the integrable systems has good universality. 展开更多
关键词 the discrete KP hierarchy the q-deformed KP hierarchy the two-component BKP hierarchy D type Drinfeld–Sokolov hierarchy addition formula Hirota bilinear equations τ function
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