共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper discusses the propagation of singularity forsemilinear wave equations.By use of the theory of para-differentialoperators and the method of microlocal analysis,some results for generalsemilinear wave equations are obtained. 相似文献
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弹性波作用下渗流多孔介质微粒运移分析是对目前静态流体或稳态多相渗流中微粒运移/捕集的补充,通过分析弹性波对微粒剥离运移捕集过程的影响,建立弹性波作用下微粒运移模型,得到对微粒运移效果和储层物性变化的影响规律。由推导得到的弹性波作用下微粒剥离临界速度可知,当微粒与孔喉半径的比值越小时弹性波导致的振荡附加力影响越大,临界速度与流体粘度、微粒/孔喉半径比成负相关,与基质胶结程度、结构力、微粒半径、微粒密度成正相关。弹性波作用下微粒运移模型需同时考虑多孔介质渗流速度的变化,此时微粒剥离释放速率增加,但随着波衰减和时间延长而降低,微粒在孔隙表面沉积滞留速率先上升后下降,喉道堵塞的速率有所上升,说明弹性波作用下微粒的剥离和悬浮能力增加,但亦增加了微粒在微细孔喉"架桥"堵塞的可能性。研究结论对岩石物理学和工业化波动处理涉及的储层物性研究具有一定指导意义。 相似文献
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Analysis of thermo-mechanical interaction in ceramic membranes subjected to heat deposition using non-Fourier law 
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下载免费PDF全文 In the paper, the influence of stain and heat effect caused by the variation of stresses in the temperature governing equation, and the influence of temperature variation in the constitutive equations and the non-Fourier effect of heat conduction are all considered, and the thermo-mechanical equation of isotropy and linear thermo-elastic material including the temperature gradient is deduced. The influence of relax time on the space-time distributions of temperature increment and stresses are discussed in the ceramic membranes with finite thickness for 1-D transient question which subjects to single pulse heat deposition. The result shows that, for the ceramic, the difference of speed between heat wave and expand wave reaches the order of magnitude, and the couple effect of thermo-mechanics has little influence on the speed of propagation. Since the single pulse heat deposition belongs to the thermal physical quantities, the heat wave is the domain speed of propagation, and the mechanical quantities belong to the high-order small quantities. 相似文献
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For azimuthal anisotropy seismic exploration, it is very important to separate the fast and slow shear waves splitting in this type of anisotropic media. Many researchers have worked on this problem, but their methods are not realistic in exploration. In this paper, a new method of separating the shear waves splitting in EDA media is presented, that can be directly applied to actual use. Through numerical examples, it can be found that the method is highly efficient and accurate. 相似文献
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Two dimensional solid phononic crystals such as plates, shells can be widely applied to the control of vibration and noise as a kind of structural materials. It is very significant to study the band gaps in two dimensional phononic crystals to apply them in the vibration and noise control for structures and as a filter for acoustical signal. The multiple-scattering theory is integrated with wave equations to study the elastic wave band gaps in two-dimensional phononic crystals. The carbon/proxy system is used as numerical example. The results show that a full band gap is presented when carbon cylinder with high propagation velocity is arranged periodically in proxy with low propagation velocity. 相似文献
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不同光波、光源距离及环境温度对异色瓢虫成虫趋光行为的影响 总被引：1，自引：1，他引：1
异色瓢虫(Harmonia axyridis)是一种常见的农田天敌昆虫,了解不同光波、光源距离及环境温度对异色瓢虫成虫趋光行为的影响,为合理设计免伤天敌昆虫的安全杀虫灯提供理论依据。本研究通过设定16 种单色光和2 种固定的对照光波,将试虫置于3 个不同光源距离的感光箱中,并设定稳定的温、湿度,通过多批重复试验,测定不同日龄和不同性别异色瓢虫成虫在不同光波和光源距离条件下的趋光率,同时还研究了不同温度下异色瓢虫对光波趋向性的变化情况。结果表明异色瓢虫成虫最为喜好的光波为500、605、550 nm,而异色瓢虫成虫最为忌避的光波则为473、407 nm;距离光源0.65 m的趋光反应率显著高于距离光源1.15 m与2.15 m处的趋光反应率;高温或低温对异色瓢虫的趋向性有一定的抑制影响。异色瓢虫成虫的趋光行为对光波、光源距离及环境温度具有较强的选择性。 相似文献
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考虑土体液相和固相的耦合作用,将基岩上覆场地土视为两相饱和多孔介质。为了考虑饱和场地土的粘弹性特性,其固相土骨架的应力应变关系利用分数阶Kelvin粘弹性模型来描述,建立了上覆分数阶粘弹性饱和场地土在简谐地震波作用下的运动控制方程。运用分数导数的性质并考虑上覆场地土的边界条件和透水性条件求解了上覆分数阶粘弹性场地土在简谐地震波作用下的振动问题,得到了饱和场地土的位移地震放大系数。采用数值算例分析讨论了分数导数的阶数、液固耦合系数、土体模型参数、基岩土体剪切模量比等参数对位移地震放大系数的影响。研究结果表明,分数导数的阶数、液固耦合系数、土体模型参数、基岩土体剪切模量比对饱和场地土的地震响应有较大的影响,通过压实场地土,可以达到增大液固耦合系数减小地震响应的作用,通过增大饱和场地土的粘性和剪切模量也可以减小地震反应。 相似文献
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《Netherlands Journal of Sea Research》1988,22(3):185-198
In a one-dimensional analytical model the origin of constant flows between connected tidal basins, as well as the origin of the associated residual levels, is examined. Linearized shallow water equations are used to describe the propagation and damping of a tidal wave in schematized (uniform width and depth) connected basins. Analytical expressions are derived for the tidal stress terms, including the contribution of the non-linear bottom-friction term, which serve as the forcing functions in the equations for the mean field. It is shown that in a first approximation the residual levels in the tidal inlets, which give boundary conditions for the tidally-averaged equations, are dependent on the tidal velocities in the inlet because of a “Bernoulli effect”. The model shows that in general differences between the fluctuating water levels at the inlets influence the residual flow more than morphological differences between two connected basins. The tidally-driven mass transport in the western Dutch Wadden Sea, directed southwards from the Vlie basin towards the Marsdiep basin, can be explained from the larger water-level amplitude at the inlet of the Vlie basin. 相似文献
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The parallel operation mechanism of 13 Bit lattice gas automata model, which can quickly compute and include more sites, is presented. Via coding and computing for particles of sites by bit, the parallel computing is achieved by transfering the particles propagation and collision into its backup and reloading. This mechanism can simulate correctly and validly some fluid motion with complex geometry boundary, such as flow through coke porous media. [WT5HZ] 相似文献
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Stress wave effect in numerical simulation on rock breaking under high pressure water jet 总被引：1，自引：0，他引：1
The evolvement of rock damage struck by a high pressure water jet is characterized by nonlinear properties, thus making it a complicated dynamic problem. Based on a nonlinear finite element and elastic plasticity theory, a computational model was established. The dynamic load striking the rock by a high pressure water jet was simulated by the dynamic contact method. Furthermore, the propagation of a stress wave in the same rock was simulated at different impact velocities. The results show that the propagation velocity of a stress wave is proportional to the impact velocity of the high pressure water jet. The effects of a stress wave in sandstone and coal impacted by high pressure water jets of the same velocity were simulated.The effect of a stress wave in coal was stronger than in sandstone, while the region of propagation of stress wave in coal was smaller. 相似文献
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The dynamic response of an underground powerhouse under seismic waves is studied by time domain BEM for anisotropic media. The responses of displacements and stresses are evaluated. The effects of angle and frequency of incident waves and the degree of media anisotropy on dynamic response of the underground structure are analyzed in detail. Some important findings for engineering are obtained. 相似文献
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According to the importance of electromechancial behavior of bone on clinical medical treatment, the physiological structure of bone tissue is studied. Then the biphasic porous media theory associated with electro kinetics is used to model the electromechanical effects in bone tissue. The finite element governing equations are built up through Galerkin method and the penalty method. The distortion of skeleton, interstitial fluid flow and the streaming potential in bone tissue are numerically computed and simulated. 相似文献
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基本培养基及附加物对蝴蝶兰原球茎增殖效果的影响 总被引：15，自引：0，他引：15
以白色花系蝴蝶兰(Phalaenopsis)的原球茎为外植体进行培养,比较不同基本培养基(1/3 MS,1/2 MS,MS,改良VW),有机添加物(椰乳,香蕉,马铃薯,苹果)和植物激素(BA,NAA)等因子对影响蝴蝶兰原球茎(Protocorm-like body,简称PLB)增殖效果进行了研究.结果表明:以改良VW为基本培养基对促进PLB增殖的效果优于MS基本培养基,在MS为基本培养时,削减大量元素的用量即降低无机盐的浓度有利于PLB的增殖.使用有机添加物对PLB增殖有影响,其中以椰乳增殖效果最好,其次为马铃薯、香蕉,苹果对PLB的增殖没有促进作用.BA及NAA的使用浓度决定PLB继续增殖或分化的方向以及进行的速度. 相似文献
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A mathematical model of rock breaking under pulsed jet is established by introducing the Johnson-Holmquist-Concrete constitutive relation and the smoothed particle hydrodynamics method. Based on this model, the formation, propagation and attenuation of stress wave during rock breaking by pulsed jet are simulated. The relations between pressure and time at different points on rock surface and the curve of peak stress wave versus distance to action spot are obtained. Destruction behaviors of rock under pulsed jet and effects on stress wave effect from jet velocity and lithology are studied according to the above calculation results, analysis results show that stress wave effect of pulsed jet acts locally and the peak stress wave shrinks sharply as the acting distance increases. The rock breaking mechanism of stress wave is tensile failure during the high speed process of load-unload. Power and effect range of stress wave is in high direct proportion with jet velocity. There is a threshold velocity before the macroscopic failure. Rocks of different lithologies have different destruction types under pulsed stress wave of pulsed jet. Destruction type of low strength rock like sandstone is crack propagation under the tensile stress during the high speed process of load-unload, while the destruction type of high strength brittle rocks like granite and limestone is vertical failure of stress concentration. 相似文献
16.
Zhang Shide 《保鲜与加工》1990,(3)
This paper studies several kinds of motion equations of nonlinear nonholonomic constraint systems. On the basis of the motion equations of the first order nonholonomic system and the theory of the zero factor of matrix multiplying from the left, the general equations of the system without undetermined multipliers is derived. By applying the method to arbitrary order nonholonomic systems, the motion equations of the systems are gained. 相似文献
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《保鲜与加工》1998,(2):35
This paper presents a discussion on various boundary integral equations reduced from the exterior Neumann problem of Helmholtz equation.The author analyses how the famous difficulty that some equations have no unique solution when the wave number k is an eigenvalue of an interior problem is arised in the course of reducing these equations from Helmholtz representations,and proposes a method of overcoming the difficulty,that is,introducing a direct boundary integral equation which has unique solution for all wave numbers k and is equivalent to the original boundary value problem.Besides,advantages and shortcomings for these integral equations are estimated respectively. 相似文献
18.
Wu Yunfang 《保鲜与加工》1991,(3)
In this paper, a solution of propagation wave in an. unconstrained damping viscoelastic cylindrical shells of infinte length under forced vibration is derived by Fourier integral transform techniques. The power flow transmitted along it is analysed. The power flow in an elastic cylindrical shell and that in a viscoelastic shell are compared. The effects of vibration reduction in two viscoelastic shells with different thickness are compared. The results provide a reference for designer in structural vibration reduction. 相似文献
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文冠果(Xanthoceras sorbifolia Bunge)是中国特有的一种抗旱耐盐的油料绿化树种,千花一果、植株变异大;扦插、嫁接等无性繁殖方式受母株繁殖材料数量和质量限制,组织培养尚存在不定芽增殖系数低、生根困难、试管苗移栽成活率低等问题。本研究基于植物组织培养进程5个阶段,分别研究其关键技术,发现文冠果茎段以有效氯浓度1.0%的二氯异氰尿酸钠水溶液消毒20 min去污染率最高,达46.7%。不定芽在添加6-苄氨基嘌呤0.8 mg/L、吲哚-3-乙酸0.05 mg/L、蔗糖30 g/L的MS培养基上培养30 d,增殖系数达5.22;在IBA 1.0 mg/L的1/2MS草炭、珍珠岩等比例混合基质上培养30 d,生根率达73.3%;在相同处理的琼脂培养基上的生根率为60.0%;在相同处理的琼脂培养基上培养15 d后,转接至活性炭琼脂培养基上培养15 d,生根率为56.7%。混合基质和琼脂培养基上的小植株驯化成活率分别为93.3%和83.3%。本研究为文冠果组织培养工厂化育苗微型快繁技术体系的建立提供基础。 相似文献
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When light spreads in gravitational wave, its frequency is changed. Usually considering frequency gravitational shift, the rest mass of the photon is neglected. According to Proca equations of weight electromagnetic wave the authors investigate the Frequency shift of Proca light. The results of numerical estimation show that frequency shift of the photon has a small change when considering the rest mass of the photon and it is not detected at present experimental condition. 相似文献