We report the first experimental observation of Beliaev damping of a collective excitation in a Bose-condensed gas. Beliaev damping is not predicted by the Gross-Pitaevskii equation and so this is one of the few experiments that tests BEC theory beyond the mean field approximation. Measurements of the amplitude of a high frequency scissors mode, show that the Beliaev process transfers energy to...

An important element of mating in the malaria vector Anopheles gambiae Giles in nature is the crepuscular mating aggregation (swarm) composed almost entirely of males, where most coupling and insemination is generally believed to occur. In this study, we mathematically characterize the oscillatory movement of male An. gambiae in terms of an established individual-based mechanistic model that pa...

Abstract In recent years, the penetration rate of installed new energy generation has been increasing, inertia system reduced, damping weakened, and anti-disturbance ability resulting in possible frequency oscillation after disturbance, which brings potential problems to safe steady operation power system. For this problem, a grid-forming control strategy storage converter is proposed, based on...

When we research the suppression problem of subsynchronous oscillation based on time domain simulation method, we find the appropriate parameters for phase compensation and amplitude gaining links are important to the damping effect of the additional damping controllers, supplementary excitation damping controller(SEDC) and subsynchronous supplementary damping controller(SSDC). Some scholars at...

this paper presents a new strategy based on multi-stage fuzzy (msf) pid controller based on artificial bee colony (abc) for damping power system stabilizer (pss) in multi-machine environment. the recent studies in artificial intelligence demonstrated that the abc optimization is strong intelligent method in complicated stability problems. also, finding the parameters of pid controller in power ...

A current source converter (CSC) based static synchronous compensator (STATCOM) is a shunt flexible AC transmission system (FACTS) device, which has a vital role in stability support for transient instability and damping support for undesirable interarea oscillations in an interconnected power network. A robust pole-shifting based controller for CSC-STATCOM with damping stabilizer is proposed. ...

We study the neutrino oscillation problem in the framework of the wave packet formalism. The neutrino state is described by a packet located initially in a region S (source) and detected in another region D at a distance R from S. We examine how the oscillation probability as a function of variable R can be derived from he oscillation probability as a function of time t, the latter being found ...

Nowadays, low frequency oscillation has become a major problem threatening the security of large-scale interconnected power systems.According to generationmechanism, active power oscillation of electric power systems can be classified into two categories: free oscillation and forced oscillation. The former results from poor or negative damping ratio of power system and external periodic disturb...

In this paper, the application of the Prony method for the estimation of dominant inter-area oscillations modes in large power systems is presented. The main goal of this paper is to compare the dominant oscillations modes extracted by the Prony method with those obtained by Eigen-value analysis. In order to achieve that, two testing systems have been designed. The first system is a multimachin...

a chaotic optimization algorithm (coa) based approach for the robust coordinated design of the upfc power oscillation damping controller and the conventional power system stabilizer has been investigated in this paper. chaotic optimization algorithms, which have the features of easy implementation, short execution time and robust mechanisms of escaping from local optimum, is a promising tool fo...