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乘积度量空间上一类隐式压缩映射的唯一不动点 被引量:3
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作者 朴勇杰 《吉林大学学报(理学版)》 CAS 北大核心 2022年第1期59-63,共5页
通过在[1,∞)^(4)上引入一类实函数G,在乘积度量空间上给出一类隐式压缩映射的唯一不动点存在性定理,并举例说明所得结果的正确性.
关键词 乘积度量空间 不动点 函数类G 隐式压缩
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乘积度量空间上具有唯一不动点的G-隐式压缩映射 被引量:1
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作者 朴勇杰 《延边大学学报(自然科学版)》 CAS 2022年第1期1-5,共5页
通过定义一个四元实函数类G并在乘积度量空间上引进G隐式压缩映射的概念,得到了在完备乘积度量空间上任何满足G隐式压缩条件的映射具有唯一不动点的定理,并由该定理推导出2个C'iric'型不动点定理.最后,通过两个实例验证了所得... 通过定义一个四元实函数类G并在乘积度量空间上引进G隐式压缩映射的概念,得到了在完备乘积度量空间上任何满足G隐式压缩条件的映射具有唯一不动点的定理,并由该定理推导出2个C'iric'型不动点定理.最后,通过两个实例验证了所得结果的正确性. 展开更多
关键词 乘积度量空间 C'iric'拟压缩 G隐式压缩 完备 不动点
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弱可压缩移动粒子半隐式方法对溃坝溢流问题的数值模拟 被引量:1
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作者 王昊 蒋勤 张长宽 《科学技术与工程》 北大核心 2014年第11期65-71,共7页
无网格粒子法(拉格朗日法)是计算流体力学领域最新一代的计算方法。由于不需要生成网格,无网格粒子法能够模拟任意形状的界面及其变形和碎裂,尤其适用于计算如溃坝溢流及波浪破碎等具有复杂自由表面运动的流体力学问题。其中,光滑粒子... 无网格粒子法(拉格朗日法)是计算流体力学领域最新一代的计算方法。由于不需要生成网格,无网格粒子法能够模拟任意形状的界面及其变形和碎裂,尤其适用于计算如溃坝溢流及波浪破碎等具有复杂自由表面运动的流体力学问题。其中,光滑粒子流体动力学方法(SPH)和移动粒子半隐式法(MPS)是无网格计算方法的典型代表。采用基于MPS法的修正弱可压缩移动粒子半隐式法(weakly compressible corrected moving particle semi-implicit method)构建了用于求解自由表面流问题的数值计算模型,并用于模拟干床面与湿床面上的溃坝溢流问题。计算结果与实验结果的对比分析表明,采用基于WCCMPS无网格法建立的数值计算模型对干、湿床面上溃坝溢流的溢流形态、水柱高度以及波前速度等均给出了良好的计算结果。 展开更多
关键词 无网格粒子法 弱可压缩移动粒子半方法(WC-CMPS) 溃坝溢流 自由表面流 数值计算模型
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一种半隐式可压缩空化流场的数值模拟方法 被引量:1
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作者 沈奕哲 刘筠乔 王本龙 《水动力学研究与进展(A辑)》 CSCD 北大核心 2021年第2期303-311,共9页
基于流体体积法(VOF),该文建立了可压缩空化流场半隐式直接数值模拟方法。并结合Zwart空化模型,建立了体积分数和守恒量的相对变化速率之间的关联,修正了各相的动量和能量方程,体现空化过程对动量和能量传递过程的影响,使用预测-校正法... 基于流体体积法(VOF),该文建立了可压缩空化流场半隐式直接数值模拟方法。并结合Zwart空化模型,建立了体积分数和守恒量的相对变化速率之间的关联,修正了各相的动量和能量方程,体现空化过程对动量和能量传递过程的影响,使用预测-校正法求解液相压力的补充方程,并通过质量分数加权汽相的状态方程获得混合相总压力。该文在一维激波管问题上验证了数值模型对激波的捕捉能力。与文献的实验结果对比,该数值方法可以有效预报亚临界和超临界雷诺数流动下的圆柱绕流空化区的大小、形状以及初生位置和尾迹等特征。 展开更多
关键词 空化 压缩 DNS VOF方法
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非完备b-度量空间上四个非连续映射具有唯一公共不动点的定理
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作者 朴勇杰 《中山大学学报(自然科学版)(中英文)》 CAS CSCD 北大核心 2021年第4期146-153,共8页
给出了在非完备的b-度量空间上满足Φ-隐式压缩条件或线性压缩条件的4个非连续的且满足弱相容条件的自映射具有唯一公共不动点的存在定理。所得结果推广和改进了许多相应的公共不动点定理。最后,给出实例支撑本文的主要结果。
关键词 公共不动点 弱相容 b-度量空间 Φ-隐式压缩
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New algorithm for solving 3D incompressible viscous equations based on projection method
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作者 牛晓峰 梁伟 +4 位作者 赵宇宏 侯华 穆彦青 黄志伟 杨伟明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第8期1826-1832,共7页
A new algorithm based on the projection method with the implicit finite difference technique was established to calculate the velocity fields and pressure.The calculation region can be divided into different regions a... A new algorithm based on the projection method with the implicit finite difference technique was established to calculate the velocity fields and pressure.The calculation region can be divided into different regions according to Reynolds number.In the far-wall region,the thermal melt flow was calculated as Newtonian flow.In the near-wall region,the thermal melt flow was calculated as non-Newtonian flow.It was proved that the new algorithm based on the projection method with the implicit technique was correct through nonparametric statistics method and experiment.The simulation results show that the new algorithm based on the projection method with the implicit technique calculates more quickly than the solution algorithm-volume of fluid method using the explicit difference method. 展开更多
关键词 implicit finite difference method 3D incompressible viscous equations projection method nonparametric statistics
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AN HMM BASED ANALYSIS FRAMEWORK FOR SEMANTIC VIDEO EVENTS 被引量:1
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作者 You Junyong Liu Guizhong Zhang Yaxin 《Journal of Electronics(China)》 2007年第2期271-275,共5页
Semantic video analysis plays an important role in the field of machine intelligence and pattern recognition. In this paper, based on the Hidden Markov Model (HMM), a semantic recognition framework on compressed video... Semantic video analysis plays an important role in the field of machine intelligence and pattern recognition. In this paper, based on the Hidden Markov Model (HMM), a semantic recognition framework on compressed videos is proposed to analyze the video events according to six low-level features. After the detailed analysis of video events, the pattern of global motion and five features in foreground—the principal parts of videos, are employed as the observations of the Hidden Markov Model to classify events in videos. The applications of the proposed framework in some video event detections demonstrate the promising success of the proposed framework on semantic video analysis. 展开更多
关键词 Video semantic analysis Hidden Markov Model (HMM) Event detection
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A unified implicit scheme for kinetic model equations. Part I. Memory reduction technique 被引量:8
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作者 Songze Chen Chuang Zhang +1 位作者 Lianhua Zhu Zhaoli Guo 《Science Bulletin》 SCIE EI CAS CSCD 2017年第2期119-129,共11页
A memory reduction technique is proposed for solving stationary kinetic model equations. As implied by an integral solution of the stationary kinetic equation, a velocity distribution function can be reconstructed fro... A memory reduction technique is proposed for solving stationary kinetic model equations. As implied by an integral solution of the stationary kinetic equation, a velocity distribution function can be reconstructed from given macroscopic variables. Based on this fact, we propose a technique to reconstruct distribution function at discrete level, and employ it to develop an implicit numerical method for kinetic equations. The new implicit method only stores the macroscopic quantities which appear in the collision term, and does not store the distribution functions. As a result, enormous memory requirement for solving kinetic equations is totally relieved. Several boundary conditions, such as, inlet, outlet and isothermal boundaries, are discussed. Some numerical tests demonstrate the validity and efficiency of the technique.The new implicit solver provides nearly identical solution as the explicit kinetic solver, while the memory requirement is on the same order as the Navier–Stokes solver. 展开更多
关键词 Implicit scheme Kinetic equation Memory reduction
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A semi-implicit three-step method based on SUPG finite element formulation for flow in lid driven cavities with different geometries 被引量:1
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作者 Cheng HUAN Dai ZHOU Yan BAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2011年第1期33-45,共13页
A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) ... A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) stabilization scheme is used for the formulation of the Navier-Stokes equations. For the spatial discretization, the convection term is treated explicitly, while the viscous term is treated implicitly, and for the temporal discretization, a three-step method is employed. The present method is applied to simulate the lid driven cavity problems with different geometries at low and high Reynolds numbers. The results compared with other numerical experiments are found to be feasible and satisfactory. 展开更多
关键词 Semi-implicit three-step method Streamline upwind/Petrov-Galerkin (SUPG) finite element method (FEM) Unsteady incompressible flows Lid driven cavity problem
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