查询词典 unstable equilibrium

A new method based on adjoint system and minus system to compute unstable equilibrium points on the stability boundary of power system classical model is proposed.

提出一种基于伴随系统和变号系统的求解电力系统经典模型稳定边界上不稳定平衡点的方法。

These are the potential energy boundary surface method and the controlling unstable equilibrium point method, respectively.

这些都是潜在的能源界面和控制不稳定平衡点法。

Power system ; unstable equilibrium point; critical cut-set ; transient angle stability

电力系统；不稳定平衡点；临界割集；暂态功角稳定性

The dynamic stability of the shell under axial compression is analyzed qualitatively by the linear equation of motion. There are three kinds of equilibrium state with different value dynamic parameter. They are stable,neutral and unstable equilibrium respectively.

利用线性的运动方程对轴压圆柱壳稳定性进行了定性分析，依动力学参数取值范围的不同，方程的解有稳定平衡、中性平衡和不稳定平衡三种情况，并给出了动力学参数与载荷参数之间的依赖关系。

They are stable,neutral and unstable equilibrium respectively. Next for a simply supported shell the relation between dynamic parameter and load parameter is given. damping and external forcing are introduced into the nonlinear equation of motion.

利用线性的运动方程对轴压圆柱壳稳定性进行了定性分析，依动力学参数取值范围的不同，方程的解有稳定平衡、中性平衡和不稳定平衡三种情况，并给出了动力学参数与载荷参数之间的依赖关系。

Secondly, method of Taylor series is used to approximate the slow manifold and the O approximation of the slow manifold is given; slow dynamics such as saddle node bifurcation which has been proven to be the same as that for the full system is analyzed; at the same time, fast dynamics including bifurcation conditions and domain of attractor of the stable equilibrium are also analyzed; the attracting region which consists of the stable manifold of the unstable equilibrium and stable equilibrium is given; we found that when the inner flux decay increases, the domain of attractor is enlarged.

首先，给出了电力系统SMIB模型的时间尺度分解，得到标准的奇异摄动模型；其次，利用幂级数方法，给出了慢流形的O近似M〓，分析了在慢流形M〓上的慢动态，得到了慢子系统的鞍结分支值，并证明此分支值与原系统的鞍结分支值相同；分析了快子系统的平衡点和全局分支的存在条件，给出由不稳定平衡点的稳定流形与稳定平衡点形成的吸引域；并研究内部电压对稳定域的影响，发现稳定域随内部电压增加而扩大；最后给出整个系统的稳定平衡点的近似吸引域。

Aimed at the problem of choosing the initial value when the Newton method is used to compute the controlling unstable equilibrium point, a practical and rigorous solving scheme was presented: by identifying the controlling load bus of the given fault, and using the Thevenin equivalent circuit to represent the rest of the system at the state of the post disturbance stable equilibrium point, using the steady equivalent circuit to represent the induction motor in composite load, and then using the torque characteristics of induction motor, a point near the CUEP is gained to be the initial value. The second order normal forms was used to approximate the stable manifold of CUEP, and the local approximating boundary of the region of attraction of the post disturbance stable equilibrium point was gained. Then just by simulating the state of the system at the fault clearing time, the transient voltage stability of the system could be determined.

针对采用牛顿法求取故障后系统主导不稳定平衡点(controlling unstable equilibrium point，CUEP)存在的初值选取难题，提出一种实用但不失严谨的解决方案：通过识别给定故障的主导负荷母线，对主导负荷母线以外系统由故障后稳定平衡点处的状态进行戴维南等值，对负荷中感应电动机部分采用其稳态等值电路，再由感应电动机的转矩特性求得CUEP附近的一个点作为近似的CUEP，以此为迭代初值可靠求得CUEP；采用二阶正规型来近似CUEP的稳定流形的方法求得近似的局部吸引域边界；由仿真得到故障清除时刻系统的状态并根据该状态是否位于吸引域内判断系统的暂态电压稳定性。

But this is an unstable equilibrium that will probably not be sustained far into next year.

最近油价回落或许是一个信号，表明全球的平衡正向着这个方向偏斜。

The results show that in a predator-prey model, when diffusion is absent, the diffusion is the interior impetus of system for its stable equilibrium state transforming to unstable equilibrium state and is the basis for biological mode forming.

研究结果表明：在捕食－食饵模型中，扩散是使无扩散时稳定的平衡态向不稳定的平衡态转变的系统内动力，是生物模式形成的基础。

A transient angle unstable mode of power system closely relates to a controlling unstable equilibrium point.

电力系统暂态功角失稳模式同相关不稳定平衡点密切相关。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。