查询词典 oscillations

The theory of accretion disks are important for many astrophysical phenomena, including Quasars, active galatic nucleic, X-ray binary stars, and young stellar objects. The most important branch of accretion djsk theory is the stability properties of djsks. It is widely considered that the luminosity variations of various astronomical objects are associated with the instability of accretion disk. The viscosity plays an important role in the accretion disk theory, and magnetic field exists commonly in astronomical phenomena. A more realistic analysis of the stabihty of the accretion disk should include both the radjal and azimuthal perturbations because of the strong shear of viscous flow.In this paper, according to the luminosity Variations of Various astronomical objects, we study the radial-azimuthal instability of an isothermal with magnetic field. We find that the radial and azimuthal fields B〓,B〓 are mainly responsible for enhancing the instability of the magneto-acoustic modes and non-axisymmetric modes,and that pulsational oscillations are larger in the radial than in the Z direction. The model may be useful in explaining the periodic light variation of FU orionis and. T Tauri stars.

在许多天体物理现象中，例如活动星系核，X-射线双星和年青的恒星理论中，吸积盘理论起着重要的作用，而吸积盘理论中的一个重要分支是吸积盘的不稳定性理论，普遍认为活动天体的周期，准周期光变现象与吸积盘的不稳定性有关，在吸积盘理论中，粘滞起着重要的作用，而磁场是天体物理中普遍存在的现象，对于几何薄吸积盘不稳定性分析，由于强剪切流的缘故，应该包括径向和环向扰动两个方面，本文结合天体物理中的各种周期，准周期光变现象，研究了含磁场的等温薄吸积盘的径向-环向振荡不稳定性，结果表明：磁场的径向和环向分量对磁声模和非轴对称模的不稳定性的增加起着主要的作用，且径向振荡大于轴向振荡，所得结果有利于解释FU Orionis和T Tauri Stars的周期光变现象。

Our findings indicate that theta and alpha band neural oscillations are involved in differentiation between environmental and personal risks.

我们的结果提示theta和alpha频段神经振荡均可区分环境和个人风险。

This project was established based on the first cooperative development of optical in situ real time detecting technique probing the atomic scale layer-by-layer epitaxy growth of oxide film. Over the last three years, we have given full play to the advantages and characteristics of both sides and have finished the assumptions and plans of this subject satisfactorily. 1. In Institute of Physics, we set up advanced oblique-incidence reflectivity difference equipment and wrote one data acquisition procedure that made the simultaneous detection of optical signal and RHEED signal into reality. 2. The first observation of sustained oscillations over hundreds of monolayers in both real and imaginary signals during the epitaxy growth of SrNb0.1Ti0.9O3 on SrTiO3 substrate in LMBE testifies that oblique-incidence is an excellent method to detect and monitor film epitaxy growth real time. 3. For the first time, we verify that oblique-incidence reflectivity difference method can be used to monitor the layer-by-layer growth mode during continuous growth through the correspondence between optical signals to atomic or molecular step edge density on the growth surface. 4. Phenomenological analysis shows that optical signals comprise three parts, the first is proportional to the average thickness of the film and depends on the bulk phase dielectric response; the second is proportional to the coverage of terraces and depends on the dielectric response of atoms or unit cells in the terrace; the third is proportional to the coverage of step edges and depends on the effective dielectric response of atoms or unit cells at step edges. This makes oblique-incident reflectivity difference technique a quantitative macroscopic method to monitor film growth.

中文摘要：本课题是在合作首次发展了氧化物薄膜原子尺度层状外延生长光学原位实时探测方法的基础上立项的，三年来，我们充分发挥双方的优势和特点，圆满完成了课题的设想和计划。1、在物理所建立了一套先进的光反射差法装置，编写了计算机系统的数据采集程序，实现了两路光学信号和RHEED数据的同步采集和显示。2、用激光分子束外延在SrTiO3基底上生长SrNb0.1Ti0.9O3薄膜，首次观测到连续外延几百个原胞层，周期振荡的光反射差实部和虚部信号，证明了光反射差法是一种能原位实时探测与监控薄膜层状外延生长的好方法。3、首次验证了通过对生长表面原子或分子台阶密度的响应，光反射差法可用于原位实时监测在连续生长条件下薄膜的层式生长模式。4、通过唯象理论的研究，证明光反射差信号由三项组成，第一项只与薄膜的平均厚度和宏观光学电介质常数有关；第二项与分子台阶面覆盖度和台阶面上分子层的光学电介质常数有关；第三项与台阶边缘的覆盖度成正比，并和在台阶边缘的分子的有效光学介电常数有关。

Here, we show that the same tSOS applied in the waking brain also induced an increase in endogenous EEG slow oscillations (0.4 1.2 Hz), although in a topographically restricted fashion.

更为有趣的是，在EEG的theta频段(4 8 Hz)，发现活动也有明显而又广泛的增强，而且，与海马相关的记忆能力，也有提高。

This paper extends the analysis for axial-system torsional oscillation into the nonlinear domain,and the research for Hopf ramification phenomena in axial-system torsional oscillation has been made using the time-domain simulating results,it verified the analysis results of similar nonlinear differential equation describing the axial-system torsional oscillations.

文中把发电机轴系扭振的分析扩展到非线性领域，并对轴系扭振中的Hopf分歧现象进行了研究，利用时域仿真结果对从描述轴系扭振的近似非线性微分方程分析所得结果进行了验证。

Oscillations could render the escalator unclimbable, and it may be a terrorist target.

震动会使电梯不可攀爬，并且它可能会成为恐怖分子的袭击目标。

The transmission capability of AC lines is sometimes limited by undamped oscillations under "steady-state" conditions.

有时，交流线路的输电容量受到"稳态"条件下非阻尼振荡的限制。

The resultant audible frequency when two sources of unequal undamped electrical oscillations of constant amplitude act simultaneously in the same circuit.

振幅为常量的非平衡无衰减电子振荡的两个振荡源在同一电路中同步振荡时产生的音频。

However, numerical modeling for nonlinear seismic waves is faced with problems such as steep gradients, shocks and unphysical oscillations. Accordingly, some special treatments have been presented to solve these problems. However, in our knowledge, there is no effective method to overcome these problems by far.

非线性弹性波的数值模拟存在陡峭间断面、数值振荡以及误差的指数级增长等现象而破坏数值解的稳定性、收敛性，能否消减上述现象的不利影响成为制约数值方法有效与否的重要因素。

Moreover, even if the background firing patterns were various and the reagent concentrations used were different, veratridine and aconitine still induced slow wave oscillations and tonic firing patterns, respectively.

这两种不同的放电模式不因背景放电或试剂浓度的不同而发生明显的改变。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。