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冲击地压应力流理论及其数值实现 被引量:16
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作者 齐庆新 王守光 +3 位作者 李海涛 穆鹏宇 杜伟升 杨冠宇 《煤炭学报》 EI CAS CSCD 北大核心 2022年第1期172-179,共8页
冲击地压作为应力敏感型动力灾害,具象化地描述应力在煤岩介质中的空间流动特征,对于冲击地压科学评价与防控具有重要意义。为此,完善了冲击地压应力流理论,指出应力流在时间上表征了应力率,在空间上表征了应力梯度,提出了应力流张量与... 冲击地压作为应力敏感型动力灾害,具象化地描述应力在煤岩介质中的空间流动特征,对于冲击地压科学评价与防控具有重要意义。为此,完善了冲击地压应力流理论,指出应力流在时间上表征了应力率,在空间上表征了应力梯度,提出了应力流张量与应力流矢量的概念及计算公式,指出应力流张量描述了不同位置、不同时刻应力的流动趋势,而应力流矢量总是与应力梯度增量方向相同。理论推导表明应力流越大的区域,应力强度因子变化越大,材料可能更易发生断裂破坏。在非线性有限元程序中开发了应力流矢量计算程序,实现了应力流的可视化,通过数值分析还原了单轴压缩试验、单煤层常规开采条件下的动态应力状态,计算结果表明:岩石单轴压缩过程中,应力流矢量呈近水平分布,向外发散;常规开采过程中,垂直方向应力流较大,由顶底板岩层指向中间煤层,水平方向应力流主要指向工作面前方,当开挖距离增大,采空区附近应力梯度明显增大,应力流矢量分布区随工作面前移。通过单轴压缩试验,发现应力流矢量方向与试样破坏变形方向较为吻合,初步验证了应力流与岩体开裂破坏的内在相关性。最后探讨了工程现场的应力流监测方法。研究成果有望为煤矿冲击危险性定量评价与差异化防治措施制定提供直观的认知形式和实用的理论工具。 展开更多
关键词 应力流张量 应力矢量 开裂破坏 应力梯度 冲击地压
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Partial energies monotonicity and holomorphicity of Hermitian pluriharmonic maps 被引量:1
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作者 YANG GuiLin HAN YingBo DONG YuXin 《Science China Mathematics》 SCIE 2013年第5期1019-1032,共14页
In this paper, we introduce the notion of Hermitian pluriharmonic maps from Hermitian manifold into Kiihler manifold. Assuming the domain manifolds possess some special exhaustion functions and the vecotor field V = J... In this paper, we introduce the notion of Hermitian pluriharmonic maps from Hermitian manifold into Kiihler manifold. Assuming the domain manifolds possess some special exhaustion functions and the vecotor field V = JMδJM satisfies some decay conditions, we use stress-energy tensors to establish some monotonicity formulas of partial energies of Hermitian pluriharmonic maps. These monotonicity inequalities enable us to derive some holomorphicity for these Hermitian pluriharmonic maps. 展开更多
关键词 stress energy tensor monotonicity formula Hermitian pluriharmonic map holomorphic map
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Blood flow of an Oldroyd-B fluid in a blood vessel incorporating a Brownian stress
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作者 ZAMAN Gul ISLAM S. +1 位作者 KANG Yong Han JUNG Il Hyo 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第1期125-131,共7页
The mechanical behavior of non-Newtonian fluids can be modeled by several constitutive differential equations. The Oldroyd model is viewed as one of the successful models for describing the response of a subclass of p... The mechanical behavior of non-Newtonian fluids can be modeled by several constitutive differential equations. The Oldroyd model is viewed as one of the successful models for describing the response of a subclass of polymeric liquids, in particular the non-Newtonian behavior exhibited by these fluids. In this paper, we are concerned with the study of the unsteady flows of an incom-pressible viscoelastic fluid of an Oldroyd-B type in a blood vessel acting on a Brownian force. First we derive the orientation stress tensor considering Hookean dumbbells on Brownian configuration fields. Then we reformulate the three-dimensional Oldroyd-B model with the total stress tensor which consists of the isotropic pressure stress tensor, the shear stress tensor, and the orientation stress tensor. Finally we present the numerical simulations of the model and analyze the effect of the orientation stress tensor in the vessel. 展开更多
关键词 fluid flow total and orientation stress tensor HEMODYNAMICS mathematical models
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f(R) gravity and Maxwell equations from the holographic principle 被引量:1
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作者 MIAO RongXin MENG Jun LI Miao 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第3期375-380,共6页
Extending the holographic program of our previous work,we derive f(R) gravity and the Maxwell equations from the holographic principle,using time-like holographic screens.We find that to derive the Einstein equations ... Extending the holographic program of our previous work,we derive f(R) gravity and the Maxwell equations from the holographic principle,using time-like holographic screens.We find that to derive the Einstein equations and f(R) gravity by a natural holographic approach,the quasi-static condition is necessary.We also find the surface stress tensor and the surface electric current,surface magnetic current on a holographic screen for f(R) gravity and Maxwell's theory,respectively. 展开更多
关键词 entropic gravity f(R) gravity Maxwell equations the holographic principle
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