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水表面横向微波一维模型的理论研究 被引量:14
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作者 戴振宏 孙金祚 隋鹏飞 《烟台大学学报(自然科学与工程版)》 CAS 2003年第1期23-28,共6页
利用水下声信号在水表面引起横向微波振幅很小的条件 ,将普遍的流体力学方程线性化 ,推导出水表面一维模型的横向微波色散关系以及波的传播形式 结果表明 :水表面横向微波具有波长短、传播速度小的特点 ,因而可以对入射到表面的激光束... 利用水下声信号在水表面引起横向微波振幅很小的条件 ,将普遍的流体力学方程线性化 ,推导出水表面一维模型的横向微波色散关系以及波的传播形式 结果表明 :水表面横向微波具有波长短、传播速度小的特点 ,因而可以对入射到表面的激光束进行调制 。 展开更多
关键词 水表面横向微波 一维模型 微弱信号检测 理想流体 水声信号检测 流体力学方程
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具有饱和土沉积层的充水河谷对平面瑞雷波的散射 被引量:11
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作者 赵成刚 王磊 李伟华 《地球物理学报》 SCIE EI CSCD 北大核心 2008年第5期1567-1573,共7页
针对具有饱和土沉积层的充水河谷对平面瑞雷波的散射问题,把半空间场地用单相弹性介质模拟,河谷中的饱和土沉积层用Biot饱和多孔介质动力理论模拟,河谷中的水假定为无黏性流体(理想流体),利用波函数展开法在频域内给出了具有饱和土沉积... 针对具有饱和土沉积层的充水河谷对平面瑞雷波的散射问题,把半空间场地用单相弹性介质模拟,河谷中的饱和土沉积层用Biot饱和多孔介质动力理论模拟,河谷中的水假定为无黏性流体(理想流体),利用波函数展开法在频域内给出了具有饱和土沉积层的圆弧形充水河谷对平面瑞雷波散射问题的解析解答.文中给出了算例,计算了不同输入频率和高宽比时河谷谷底的位移幅值.算例表明由于具有饱和土沉积层的充水河谷存在,使得河谷谷底的位移幅值放大4倍多,并且它的幅值随着河谷谷底位置的不同而产生较大的变化. 展开更多
关键词 河谷 平面瑞雷波 散射 饱和土 理想流体
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具有饱和土沉积层的充水河谷对平面波的散射 被引量:10
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作者 李伟华 赵成刚 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2006年第1期212-224,共13页
把波函数展开方法用于地震波散射问题的研究中,首次在频域内给出了具有饱和土沉积层的圆弧形充水河谷对平面P波和SV散射问题的解析解答.其中半空间场地用单相介质弹性动力理论模拟,河谷中的饱和土沉积层用饱和多孔介质的Biot动力学理论... 把波函数展开方法用于地震波散射问题的研究中,首次在频域内给出了具有饱和土沉积层的圆弧形充水河谷对平面P波和SV散射问题的解析解答.其中半空间场地用单相介质弹性动力理论模拟,河谷中的饱和土沉积层用饱和多孔介质的Biot动力学理论模拟,河谷中的水用无黏性流体(理想流体)介质模拟.文中还给出算例,计算了不同高宽比的河谷谷底的位移幅值,分析表明河谷地形的存在使得半空间介质表面的位移幅值随着观察点位置的变化变化较大. 展开更多
关键词 饱和土 理想流体 河谷 平面波 散射
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Artificial Intelligence as a Check on Logic
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作者 Edwin Eugene Klingman 《Journal of Applied Mathematics and Physics》 2024年第9期3148-3162,共15页
Math and physics proceed from assumptions to conclusions via a logical path. Artificial intelligence possesses the ability to follow logic, herein specifically applied to the problem of defining ontologically real 2D ... Math and physics proceed from assumptions to conclusions via a logical path. Artificial intelligence possesses the ability to follow logic, herein specifically applied to the problem of defining ontologically real 2D manifolds in a 3D continuum. Vortices and tori in fluids exhibit effective 2D surfaces, which, treated as manifolds, allow application of calculus on the boundaries of the structures. Recent papers in primordial field theory (PFT) have employed Calabi-Yau geometry and topology to develop a fermion structure. We desire a logical justification of this application and herein explore the use of artificial intelligence to assist in logic verification. A proof is outlined by the author and formalized by the AI. 展开更多
关键词 AI CALABI-YAU YANG-MILLS perfect fluid Fermion Structure MANIFOLD 3D Continuum
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Representation of Physical Fields as Einstein Manifold
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作者 Vu B. Ho 《Journal of Applied Mathematics and Physics》 2023年第3期599-607,共9页
In this work we investigate the possibility to represent physical fields as Einstein manifold. Based on the Einstein field equations in general relativity, we establish a general formulation for determining the metric... In this work we investigate the possibility to represent physical fields as Einstein manifold. Based on the Einstein field equations in general relativity, we establish a general formulation for determining the metric tensor of the Einstein manifold that represents a physical field in terms of the energy-momentum tensor that characterises the physical field. As illustrations, we first apply the general formulation to represent the perfect fluid as Einstein manifold. However, from the established relation between the metric tensor and the energy-momentum tensor, we show that if the trace of the energy-momentum tensor associated with a physical field is equal to zero then the corresponding physical field cannot be represented as an Einstein manifold. This situation applies to the electromagnetic field since the trace of the energy-momentum of the electromagnetic field vanishes. Nevertheless, we show that a system that consists of the electromagnetic field and non-interacting charged particles can be represented as an Einstein manifold since the trace of the corresponding energy-momentum of the system no longer vanishes. As a further investigation, we show that it is also possible to represent physical fields as maximally symmetric spaces of constant scalar curvature. 展开更多
关键词 General Relativity Einstein Manifold Energy-Momentum Tensor Electromagnetic Field perfect fluid Maximally Symmetric Spaces
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Late Time Behavior of the Cosmological Model in Modified Theory of Gravity
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作者 Sankarsan Tarai Jagadish Kumar 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2022年第4期1019-1031,共14页
We report a viable exponential gravity model for the accelerated expansion of the universe in Bianchi VI<sub>h</sub> space-time. By considering the estimated physical parameters, the cosmological models ar... We report a viable exponential gravity model for the accelerated expansion of the universe in Bianchi VI<sub>h</sub> space-time. By considering the estimated physical parameters, the cosmological models are constructed and analyzed in detail. We found that the state parameter in both the models increases to a higher negative range in an early epoch of the phantom domain and it goes to the positive domain at a late phase of the evolution. The effective cosmological constant remains in a positive domain for both models, which is a good sign of accelerating expansion of the universe. 展开更多
关键词 f (R T) Gravity Bianchi Type VIh perfect fluid
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Einstein Rosen Mesonic Perfect Fluid Cosmological Model with Time Dependent Λ-Term
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作者 Vijay G. Mete Vijay D. Elkar 《International Journal of Astronomy and Astrophysics》 2016年第1期99-104,共6页
Mesonic perfect fluid solutions are found in general relativity with the aid of Einstein’s Rosen cylindrically symmetric space time. A static vacuum model and a non-static cosmological model corresponding to perfect ... Mesonic perfect fluid solutions are found in general relativity with the aid of Einstein’s Rosen cylindrically symmetric space time. A static vacuum model and a non-static cosmological model corresponding to perfect fluid are investigated. The cosmological term Λ is found to be a decreasing function of time which is supported by the result found from recent type Ia Supernovae observations. The various physical and geometrical features of the model are discussed. 展开更多
关键词 General Relativity perfect fluid Time-Dependent Term Λ
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LRS Bianchi Type-I Universe with Anisotropic Dark Energy in Lyra Geometry
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作者 Kishor S. Adhav 《International Journal of Astronomy and Astrophysics》 2011年第4期204-209,共6页
The exact solutions of the Einstein field equations for dark energy (DE) in Locally Rotationally Symmetric (LRS) Bianchi type-I metric under the assumption on the anisotropy of the fluid are obtained for exponential v... The exact solutions of the Einstein field equations for dark energy (DE) in Locally Rotationally Symmetric (LRS) Bianchi type-I metric under the assumption on the anisotropy of the fluid are obtained for exponential volumetric expansion within the frame work of Lyra manifold for uniform and time varying displacement field. The isotropy of the fluid and space is examined. 展开更多
关键词 LRS Bianchi Type-I Space-Time perfect fluid ANISOTROPIC Dark Energy Lyra Geometry
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About One Discrete Mathematical Model of Perfect Fluid
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作者 Konstantin Eduardovich Plokhotnikov 《Open Journal of Modelling and Simulation》 2016年第3期129-167,共40页
In work, it is constructed a discrete mathematical model of motion of a perfect fluid. The fluid is represented as an ensemble of identical so-called liquid particles, which are in the form of extended geometrical obj... In work, it is constructed a discrete mathematical model of motion of a perfect fluid. The fluid is represented as an ensemble of identical so-called liquid particles, which are in the form of extended geometrical objects: circles and spheres for two-dimensional and three-dimensional cases, respectively. The mechanism of interaction between the liquid particles on a binary level and on the level of the n-cluster is formulated. This mechanism has previously been found by the author as part of the mathematical modeling of turbulent fluid motion. In the turbulence model was derived and investigated the potential interaction of pairs of liquid particles, which contained a singularity of the branch point. Exactly, this is possible to build in this article discrete stochastic-deterministic model of an ideal fluid. The results of computational experiment to simulate various kinds of flows in two-dimensional and three-dimensional ensembles of liquid particles are presented. Modeling was carried out in the areas of quadratic or cubic form. On boundary of a region satisfies the condition of elastic reflection liquid particles. The flows with spontaneous separation of particles in a region, various kinds of eddy streams, with the quite unexpected statistical properties of an ensemble of particles characteristic for the Fermi-Pasta-Ulam effect were found. We build and study the flow in which the velocity of the particles is calibrated. It was possible using the appropriate flows of liquid particles of the ensemble to demonstrate the possibility to reproduce any prescribed image by manipulating the parameters of the interaction. Calculations of the flows were performed with using MATLAB software package according to the algorithms presented in this article. 展开更多
关键词 perfect fluid Discrete Model Liquid Particle Branch Point TURBULENCE Interaction in the Cluster The Laws of Conservation Stochastic and Deterministic Components of the Flow Computational Experiment The Separation of Particles The Effect of the Fermi-Pasta-Ulam Calibration of Particle Velocities
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Bianchi Type-V Cosmological Models for Perfect Fluid with Time-Varying Gravitational and Cosmological Constant
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作者 Mohammed Aman Ullah Mohammad Amjad Hossain Mohammad Moksud Alam 《Journal of Applied Mathematics and Physics》 2017年第11期2283-2290,共8页
Einstein’s field equations with variable gravitational and cosmological constants are considered in presence of perfect fluid for locally-rotationally-symmetric (LRS) Bianchi type-V space-time discussion in context o... Einstein’s field equations with variable gravitational and cosmological constants are considered in presence of perfect fluid for locally-rotationally-symmetric (LRS) Bianchi type-V space-time discussion in context of the particle creation. We present new shear free solutions for both absence and presence of particle creation. The solution describes the particle and entropy generation in the anisotropic cosmological models. We observe that time variation of gravitational and cosmological constant is needed for particle creation phenomena. Moreover, we obtained the particle production rate Γ(t) for this model and discussed in detail. 展开更多
关键词 LRS Bianchi Type-V perfect fluid GRAVITATIONAL CONSTANT COSMOLOGICAL CONSTANT Particle Creation
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Dynamics of Bianchi I Universe in Extended Gravity with Scale Factors
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作者 Fakhereh MD. Esmaeili 《Journal of High Energy Physics, Gravitation and Cosmology》 2018年第4期716-730,共15页
In this paper, the dynamical behavior of an anisotropic universe in an extended gravity e.g. the f (R,T ) theory of gravity is studied. We use f (R,T ) = R + 2μT , where R is the Ricci scalar, T is the trace of energ... In this paper, the dynamical behavior of an anisotropic universe in an extended gravity e.g. the f (R,T ) theory of gravity is studied. We use f (R,T ) = R + 2μT , where R is the Ricci scalar, T is the trace of energy-momentum tensor and μ is a constant. Two cosmological models are constructed using the power law expansion and hybrid law cosmology in Bianchi type I universe, where the matter field is considered to be a perfect fluid. It is found that in both the cases the anisotropic behavior is in agreement with the observational results. The state finder diagnostic pair and energy conditions are also calculated and analyzed. 展开更多
关键词 f (R T ) GRAVITY Bianchi Type I perfect fluid ANISOTROPIC UNIVERSE SEC
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Scale Invariant Theory of Gravitation in Einstein-Rosen Space-Time
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作者 Bivudutta Mishra Pradyumn Kumar Sahoo Addepalli Ramu 《Journal of Modern Physics》 2010年第3期185-189,共5页
In this paper, we have studied the perfect fluid distribution in the scale invariant theory of gravitation, when the space-time described by Einstein-Rosen metric with a time dependent gauge function. The cosmological... In this paper, we have studied the perfect fluid distribution in the scale invariant theory of gravitation, when the space-time described by Einstein-Rosen metric with a time dependent gauge function. The cosmological equations for this space-time with gauge function are solved and some physical properties of the model are studied. 展开更多
关键词 Scale INVARIANT SPACE-TIME perfect fluid
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引力塌缩系统的熵变
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作者 张祖全 《武汉大学学报(自然科学版)》 CSCD 1998年第3期351-353,共3页
在共动坐标系下,对引力塌缩系统的熵变进行了研究,证明了理想流体系统的塌缩是等熵过程,有辐射热流的开放系统的塌缩是减熵过程.对非理想流体系统推出了熵变的一般公式,并应用到有辐射中微子的塌缩过程,其总熵是减少的.
关键词 塌缩 黑洞 理想流体 引力塌缩系统
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球对称静态荷电理想流体爱因斯坦方程的严格解
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作者 厉江帆 黄春佳 +1 位作者 方家元 黄祖洪 《长沙水电师院学报(自然科学版)》 2000年第2期69-71,共3页
获得球对称静态荷电理想流体爱因斯坦方程的严格解 ,此解在边界上与Reissner Nordstro··m度规相衔接 ,在球内 ,度规是正则的 ,质量密度、电荷密度、压强是有限的 .作为特例 ,此解包含了以前由Wang(1 987)
关键词 理想流体 爱因斯坦方程 严格解 球对称静态荷电
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非均匀平面对称的Quintessence宇宙模型
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作者 王剑苹 沈明 《福州大学学报(自然科学版)》 CAS 北大核心 2016年第1期12-16,共5页
构造一类特殊的非均匀平面对称度规,利用理想流体的能动量张量,在Quintessence模型的假设下求解Einstein场方程,得到一类带有暗能量性质的非均匀平面对称宇宙模型.此外,通过计算模型的Hubble参数和减速因子等物理量,分析了模型的物理性质.
关键词 EINSTEIN场方程 理想流体 暗能量 Quintessence模型
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荷电流体球的无奇异性解
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作者 厉江帆 《长沙水电师院自然科学学报》 1993年第4期378-382,398,共6页
在本文中,我们获得了广义相对论中静态荷电理想流体球的无奇异性解。此解在边界上与Reissuer—Nordsdrom度规相衔接,在球内满足物理条件。
关键词 荷电流体球 方程 度规 理想流体
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球对称均匀星的引力坍缩
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作者 冯胜奇 《黄冈师范学院学报》 1993年第2期25-29,共5页
本文首先从一般的角度讨论了球对称均匀星的引力坍缩问题,并且将该问题总结为求解两个一阶非线性的微分方程组;然后具体计算了当星体的状态方程为p=βζ(此处β是一个常数)时的坍缩解;最后我们对该问题作了进一步的讨论并指出外部观察... 本文首先从一般的角度讨论了球对称均匀星的引力坍缩问题,并且将该问题总结为求解两个一阶非线性的微分方程组;然后具体计算了当星体的状态方程为p=βζ(此处β是一个常数)时的坍缩解;最后我们对该问题作了进一步的讨论并指出外部观察者是无法观察星体坍缩到Schwarzschild半径之后的情况。 展开更多
关键词 理想流体 引力坍缩 奇点
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Bianchi Type-II, VIII &IX Perfect Fluid Cosmological Models in Brans Dicke Theory of Gravitation
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作者 Velagapudi Uma Maheswara Rao Mandangi Vijaya Santhi 《Journal of Modern Physics》 2011年第10期1222-1228,共7页
Field equations in the presence of perfect fluid distribution are obtained in a scalar tensor theory of gravitation proposed by Brans and Dicke[1] with the aid of Bianchi type-II, VIII & IX metrics. Exact prefect ... Field equations in the presence of perfect fluid distribution are obtained in a scalar tensor theory of gravitation proposed by Brans and Dicke[1] with the aid of Bianchi type-II, VIII & IX metrics. Exact prefect fluid Bianchi type- IX cosmological model is presented since other models doesn’t exist in Brans-Dicke scalar tensor theory of gravitation. Some physical properties of the model are also discussed. 展开更多
关键词 Bianchi TYPE-II VIII & IX Brans Dicke SCALAR Tensor THEORY perfect fluid Distribution
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Gravitational collapse with standard and dark energy in the teleparallel equivalent of general relativity
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作者 Gamal G.L.Nashed 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期57-62,共6页
A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity (TEGR). A spacetime which is not asymptotically fiat is derived. The energ... A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity (TEGR). A spacetime which is not asymptotically fiat is derived. The energy conditions of this spacetime are studied. It is shown that after some time the strong energy condition is not enough to satisfy showing a transition from standard matter to dark energy. The singularities of this solution are discussed. 展开更多
关键词 perfect fluid with self-similarity of second kind teleparallel equivalent of general relativ-ity asymptotically nonflat spacetime energy conditions
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Rotating Squeezed Vacua as Time Machines
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作者 S. Al Saleh L. A. Al Asfar A. Mahroussah 《Journal of Modern Physics》 2016年第3期304-311,共8页
Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticit... Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level. 展开更多
关键词 Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s) because they have a negative energy density. When treated as a perfect fluid rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry but because of violation of ANEC the Cauchy horizon lies outside the system unlike Kerr blackholes giving more emphasis on whether spacetime is multiply connected at the microscopic level.
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