查询词典 absolute instability

In addition, the absolute/convective instability is studied, and the governing region in the parameter plane is declared. It is shown that the absolute instability may become predominant when the electric field or the surface tension is sufficiently large.

另外，研究了单流体射流的绝对和对流不稳定性，在参数平面上给出了它们的控制区域，发现在电场强度足够大或表面张力足够大时，射流可能由对流不稳定状态进入绝对不稳定状态。

The formation mechanism of the absolute instability and gyrotron backward wave oscillations is analyzed, and the methods to suppress the parasitical modes are discussed.The nonlinear theory model of gyro-TWT is consummated by considering the influence of tapered magnetic field and waveguide radius, electron velocity spread, and waveguide loss on electron beam-wave interaction. The large-signal characteristic of gyro-TWT, such as launching loss and absolute instability, are also analyzed in detail. This work establishes the foundation for the development of a gyro-TWT amplifier.

重点研究了两段损耗波导结构和损耗陶瓷结构回旋行波管中的电子注-波互作用，分析了绝对不稳定性和回旋返波振荡的形成机制和抑制寄生模式的方法；完善了回旋行波管的非线性理论模型，并考虑了磁场和波导半径渐变、速度零散、波导损耗等因素对注-波互作用的影响；详细分析了发射损耗、相位稳定性等回旋行波管的大信号特征，为回旋行波管放大器的研制奠定了基础。

When the conditional symmetric instability lies in the middle level and conditional instability in the lower and upper levels, the circulation will have updrafts through the total column of the atmosphere. The release of conditional instability gives rise to a mesoscale rain belt.

当低层和高层出现条件不稳定，中间呈条件对称不稳定或弱稳定度层结时，从低层到高层出现较深厚的垂直上升气流，湿重力不稳定能量的释放导致了云带的形成。

The results show that the decalescence of catalyst bed affects the process of hydrogen peroxide catalytic decomposition greatly. If the catalyst bed is preheated or made up of materials with low thermal conductivity, that influence can be depressed. At the same time, the response characteristic of catalyst bed and the efficiency of catalytic decomposition can be improved. The low frequency pressure instability of catalyst bed occurs because of the coupling of catalytic decomposition and supplying. The decomposition plane pushes all the way through the catalyst bed during pressure oscillations, causing unreacted liquid hydrogen peroxide to be exhausted from the bed and leading to the appearance of liquid hydrogen peroxide channeling. Consequently, how to prevent or at least limit this channeling is the key to eliminate the pressure instability of catalyst bed. It was found that adding clapboard to the catalyst bed can depress the pressure instability efficiently.

结果表明催化剂床及催化剂的吸热对过氧化氢分解过程影响很大，对催化剂床进行预热或采用热导率低的材料制造催化剂床等措施，可以降低催化剂床壁面吸热对催化分解过程的影响，提高催化剂床的响应特性和催化分解效率；催化剂床的低频不稳定是催化分解过程与供应系统耦合产生的，催化剂床气体界面的波动过程中，液体过氧化氢穿透催化剂床形成过氧化氢液体通道，过氧化氢液体通道的产生和扩大是催化剂床不稳定的主要原因，也是消除催化剂床不稳定的关键，试验中在催化剂床内加入分流板成功地抑制了催化剂床的低频不稳定。

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。

The high frequency combustion instability in liquid rocket engine LRE is analyti cally studied by usin g CFD methods.The comprehensive model and governing equations for numerical simu lation of high frequency combustion instability are presented.The PISO and MacCo rmack algorithms are compared in this study.Both methods can successfully handle combustion instability analysis.

应用CFD方法对液体火箭发动机中的高频燃烧不稳定性进行了分析研究，建立了液体火箭发动机不稳定燃烧数值模拟的综合模型和控制方程，比较了PISO和Ma cCormack两种算法，得出了两种算法均能成功应用于不稳定燃烧分析的结论。

The larger subharmonic component will be introduced into the system after the instability of system periodic motions, the motion of systems will be nonsynchronous precession and the amplitude of alternate stress in the rotor shaft is high. The long-term existence of instability will directly threaten the safe running of the rotor systems. Research on the influence of the change of system parameters on the system dynamical behaviors, the stability of system periodic solutions with the change of system rotational speed and the system motion after instability will have the theoretical and engineering-oriented significance for the long-term safe running of large-scale rotating machinery.

转子系统失稳后会产生较大的低频振动分量，系统运动出现非协调进动，系统转轴中会产生幅值很大的交变应力，转子失稳状态的存在直接影响系统的安全运行，因此研究转子系统自身参数的变化对系统动力稳定性的影响，研究系统周期解随工作转速的变化情况及其失稳后的运动规律，对大型旋转机械的安全稳定运行具有重要的理论意义和工程实用价值。

Overbreak excavation instability and local instability are indicated on the phase of construction about soil nail wall on the base of different instability situation about two cases,when excavation beginning.

结合两个纯土钉墙工程实例，根据工程失稳时新开挖土层的不同失稳现象，提出了土钉墙施工失稳有超挖失稳和局压失稳两种类型。

Fracture is caused by sheet's tensile instability, Hill's totalized instability theories and Swift's diffuse instability theories which based on continuous mechanics are applied to isotropic blank; Marciniak and Kuczynski's theories are applied to orthotropic blank, which introduced thickness imperfections normal to the principal stress and strain direction as a groove pre-existing defects in the material. The stability of each part of blank at each moment is described by numerical method, and the results are shown by computer simulation, thus the fracture in sheet forming can be predicted preciously.

拉裂是由于拉伸失稳引起的，以连续体力学为基础的Hill集中性失稳理论和Swift分散性失稳理论应用到各向同性板料进行失稳判定；将Marciniak和Kuczynski的凹槽损伤失稳理论应用到正交各向异性板料拉伸失稳判定，对板料各处在成型过程中不同时刻的稳定性进行数值化描述，并运用计算机仿真技术进行直观的表现，可以准确地预测板料成型中可能出现的拉裂现象。

Firstly, we simulate the influence of pump waves on two-stream instability occurred at heights of equatorial ionospheric E region. The simulation results show that pump waves can control the two-stream instability, that's to say, pump radio can stabilized or unstabilized this instability.

首先，模拟了加热泵波对赤道电离层E区双流不稳定性的影响，模拟结果定性地表明，在一定条件下，加热泵波对发生在该区域的双流不稳定性有很好的致稳或不稳作用。

Summary In copyright infringement cases,if the alleged infringer uses or even plagiarizes the copyrighted works or parts thereof,which causes no substantially adverse effect on the normal exploitation of the work,nor does it inflict any substantial damages to the right owner,the de minis doctrine should be applied to exempt the liabilities of the defendant and seek the balance of interests between the right owner and the general public embodied by the copyright law.

在侵犯著作权案件中，如果被控侵权行为人虽未经著作权人的同意，使用甚至抄袭了受著作权保护的作品或作品的片段，但若情节轻微，未对该作品的正常使用产生任何实质不利的影响，亦未对权利人的权利造成实质性的损害，则应适用&不计琐细原则&，免除行为人的责任，以寻求在权利人利益与著作权法所体现的社会公共利益之间的平衡。

This new product will become our best seller.

这个新产品会成为我们最畅销的产品。