查询词典 periodicity of function

That seem to indicate that there is periodicity in the abundances of measured galaxy redshifts...

&得到提示和确认。。。；这是一篇在网上出现频次很高的论文，用时髦的话来讲&很火

Rhythms are generally characterized by episodicity, cyclicity or periodicity, and make up synthetically differtent development stages.

节律具有突发性和旋回性或周期性，总的构成不同的发展阶段。

The following exciting results are revealed: 1 When considering the influence of some nonlinear elements such as hard-limit of exciters, the effects of some devices such as Power System Stabilizer and Static Var Compensator which can introduce positive damping in power system, the reasonability of system parameter values in simulation, the SNB surface and HB surface on the boundary of SSSR will turn close to each other and even coalesce together; 2 Under some conditions, coupling between slow exciters and shunt capacitors will bring negative damping in power system dynamics, which increases the possibility of oscillatory instability. So the power system with mass shunt compensators is easily subjected to the oscillatory instability. In recent years, chaotic phenomena of power system have been reported many times. Some simulation studies even found chaos existing inside the power system SSSR. In this dissertation, chaotic phenomena in power systems are thoroughly studied in order to make clear the relation of chaos and SSSR. The following results are derived: 1 Based on Li-Yorke Theorem and their definition on the chaos, the existence of chaos in power system is verified; 2 Three possible routes of causing chaos in power system are found and deeply investigated. They are route of cascading period doubling, route of directly initial energizing and route of torus bifurcation (or quasi-periodicity). The latter two routes are investigated for the first time in power system stability studies; 3 When the stability conditions of chaos are broken, it is found they can lead to voltage collapse, angle divergence, or voltage collapse with angle divergence simultaneously.

针对在电力系统小扰动稳定区域内可能存在混沌吸引域的有关报道，本文深入研究了电力系统混沌现象的出现途径和与系统失稳模式之间的关系：1利用Li-Yorke定理和Li-Yorke的混沌定义，从理论上证明了电力系统混沌现象的存在性；2发现了电力系统中导致混沌出现的三种可能途径：倍周期分岔导致混沌、初始能量直接激发混沌和经由环面分岔导致混沌，并对后两种新发现的途径进行了较为细致的研究；3发现了混沌极限环破裂导致电压崩溃、角度失稳以及电压崩溃和角度失稳同时出现的现象，其中混沌极限环破裂导致系统角度失稳和电压崩溃及角度失稳同时出现的现象均属首次报道；4证明由微分-代数方程描述的系统模型，其小扰动稳定域的边界只包含HB、SNB和SIB三种分岔界面，在SSSR的内部和边界上，均不可能存在会导致混沌的点，从而将混沌现象排除在小扰动稳定域的研究之外，简化了后者的研究工作。

The discipline of influenza activity in Changsha is significant, and it shows seasonal nature and periodicity. The vary trend of ILI% can explain the activities of local' influenza much better. The level of ILI% is on its two fastigiums while the activities of influenza virus are just on theirs. The A H1N1 influenza has much more influence to seasonal influenza activities, and the prevention and control emphasis of A H1N1 influenza should be enhanced hereafter.

长沙市流感活动的规律较为明显，存在季节性和周期性；ILI%的变化能够较好地反映当地流感病毒的活动情况，流感病毒活动的两个高峰时期当地的ILI%水平也处于高峰时期；甲型H1N1流感病毒对季节性流感病毒的活动影响较大，今后一段时间内防控的重点应放在甲型H1N1流感的防控中。

The imaginary time formalism has the character of the periodicity ofimaginary time, and the real time formalisms are charactered by the doubling ofdegrees of freedom.

虚时方法的特征是有周期性的虚时间，而各种实时方法的共同特征是倍自由度。

The results show that the hal＆daily and half-monthly tidal wave perio- dicity changed abnormally about one month before the earthquake, with periodicity disappearing and amplitude reducing, but they recovered after it with clearer state than that at normal time.

分析了在2004年12月26日印尼8.7级地震前河北昌黎台记录到的自然电位及电场异常，结果显示昌黎台自电位、电场正常时段观测到的半日、半月潮汐波周期变化在震前1个多月发生畸变，周期消失，变化幅度相应减小，震后快速恢复，且潮汐波记录比震前正常时段更加清晰。

The simulations for the obtaining result in Ku wave band show that the size of the pricipal target affects greatly both the forward sactter and the backward scatter. The influence of the targets around shows definite periodicity. The second scatter field minishes with the increase of distance between two targets. The more near the forward area the rounding target is, the bigger its affect is.

结果表明：本目标的尺寸对前向散射和后向散射均有较大的影响，周围目标的影响呈现出一定的周期性，二次散射随着目标间距的增大而减小，周围目标离前向散射方向越近，对前向散射的影响也越大。

The continuously varying of the refractive index is considered, and according to the property of holographic material, the small wavenumber approximation is utilized and the periodicity of the grating is used.

在矩阵建立过程中考虑了介质折射率是连续变化的，并且根据全息介质的特性采用小波数近似，同时充分利用了光栅结构的周期性特点。

The results show that the high-order effects destroy the periodicity of high-order solitons evolution.

计算结果表明：高阶效应使高阶孤子的演化不再具有周期性特性。

Comes from the evidence of our sens es and stomachs, and the periodicity

就是当我们生活在一个特定的时区所经历的周期性。

We are forbidden from giving money to these shoeless, skinny children, as this will perpetuate begging.

向光着脚，骨瘦如柴的孩子施舍是不可以的，因为要招来无休无止的乞讨。

It would be hard not to fall victim to some sharpeyed policeman.

要想不被某个目光锐利的警察抓到，谈何容易。