Peculiar Oscillation Research Articles

Black and gray solitons in holographic superfluids at zero temperature

We construct gray soliton configurations, which move at constant speeds, in holographic superfluids for the first time. Since there should be no dissipation for a moving soliton to exist, we use the simplest holographic superfluid model at zero temperature, considering both the standard and alternative quantizations. For comparison purpose, we first investigate black solitons in the zero temperature holographic superfluids, which are static configurations. Then we focus on the numerical construction of gray solitons under both quantizations, which interpolate between the (static) black solitons and sound waves (moving at the speed of sound). Interestingly, under the standard quantization, a peculiar oscillation of the soliton configurations is observed, very much resembling the Friedel oscillation in fermionic superfluids at the BCS regime. Some implications and other aspects of the soliton configurations are also discussed.

Nonlinear Analysis of Two-layer Fluid Sloshing in a Rectangular Tank Subjected to Width Direction Excitation

This paper describes a nonlinear theory to describe oscillations of two liquid layers formed in a rectangular tank. Nonlinear equations based on the variational principle and the Galerkin method are used, which are written in a form of direct expanding in eigenmodes. Analysis using the equations is described under the experimental conditions reported in a previous study. Both the experiment and the analysis demonstrate a “peculiar oscillation” in which the interface of the two liquids oscillates at 1/5 to 1/7 of the excitation frequency in a particular excitation frequency range. By observing the nonlinear force time series, four eigenmodes are identified to be mainly relevant to the oscillation. An amplitude equation analysis was applied to the four relevant eigenmodes. It was found that this “peculiar oscillation” is one of summed and differential harmonic oscillations (combination oscillation) in which one asymmetric and one symmetric eigenmode excite each other through the mediation of other two asymmetric eigenmodes.

Anomalous Friedel oscillations in a quasihelical quantum dot

The charge and spin patterns of a quantum dot embedded into a spin-orbit coupled quantum wire subject to a magnetic field are investigated. A Luttinger liquid theory is developed, taking into account open boundaries and a finite magnetic field. In the quasihelical regime, when spin-orbit effects dominate over the Zeeman interaction, peculiar states develop at the Fermi surface of the dot. Anomalous Friedel oscillations with twice the expected wavelength develop in the total tunneling rate from a scanning tunneling microscope tip, accompanied by a peculiar oscillation of spin-resolved transport properties. Both effects are analyzed in detail. The stability against electron interactions and magnetic field is investigated. We also discuss how signatures of such states survive in the total charge and spin densities.

Magnetized strongly coupled plasmas and how to realize them in a dusty plasma setup

Strongly coupled plasmas in which the interaction energy exceeds the kinetic energy play an important role in many astrophysical and laboratory systems including compact stars, laser plasmas and dusty plasmas. They exhibit many unusual collective properties, such as liquid or crystalline behaviour, peculiar oscillation spectra and transport properties. Recently, strongly coupled plasmas were studied in the presence of a strong magnetic field by computer simulations, and strong modifications of their transport properties and oscillation spectra were observed. While strong magnetization is common in stellar systems it is practically impossible to achieve in complex plasmas due to the large mass of the dust particles. Here we discuss a recently demonstrated approach to achieve very strong ‘magnetization’ by a rotation of the neutral gas, and we present new results for macroscopic two-dimensional systems.

Numerical analysis of double-diffusive convection in a porous enclosure due to opposing heat and mass fluxes on the vertical walls – Why does peculiar oscillation occur?

Peculiar oscillating convection is observed when two-dimensional double-diffusive convection in porous medium is analysed numerically. The top and bottom walls of an enclosure are insulated, and constant and opposing heat and mass fluxes are prescribed on the vertical walls. The peculiar oscillations are of three types: (1) Chaotic oscillations wherein the main flow is due to temperature; however, the convection due to concentration is strong enough to generate this peculiar oscillation. (2) The ‘sudden steady state case’ caused by the shifts from thermally-driven to concentration-driven forces. (3) The ‘re-oscillation case’ caused by the convection pattern changes from centrosymmetric to non-centrosymmetric.

Low-Density Series Expansion for the Domany-Kinzel Model

Domany-Kinzel (DK) model is a family of the 1+1 dimensional stochastic cellular automata with two parameters p 1 and p 2 , which simulate time evolution of interacting active elements in a random medium. By identifying a set of active sites on the spatio-temporal plane with a percolation cluster, we discuss the directed percolation (DP) transitions in the DK model. We parameterize p 1 = p and p 2 = α p with p ∈[0,1] and α∈[0,2] and calculate the mean cluster size and other quantities characterizing the DP cluster as the series of p up to order 51 for several values of α by using a graphical expansion formula recently given by Konno and Katori. We analyze the series by the first- and second-order differential approximations and the Zinn-Justin method and study the dependence on α of the convergence of estimations of critical values and critical exponents. In the mixed site-bond DP region, 1 ≤α≤ 1.3553, the convergence is excellent. As α→2 slowing down of convergence and as α→0 peculiar oscillation of estim...

Reactor experiments on type-I and type-II BWR stability

Investigations on Type-I (hydrostatic head) and Type-II (density wave) BWR stability characteristics are reported. Experimental data are obtained from the Dodewaard natural-circulation BWR at conditions far away from nominal operating points. The Type-I stability boundary was reached; the Type-II stability boundary was crossed. At this latter unstable condition the reactor power showed peculiar oscillation modulations. Experimentally obtained decay ratios and resonance frequencies are put into context using a physical model. Flashing is shown to be an important phenomenon for driving the coolant flow at start-up conditions and for Type-I stability features. From low-pressure experiments, it appears that the decay ratio is an unsafe measure for Type-II stability close to the stability boundary.

Experimental Study on Oscillation of Single Spike of Magnetic Fluid under Vertical Alternating Magnetic Field.

Experiments were made on the oscillation of a single spike of a magnetic fluid droplet under a vertical alternating magnetic field. A kind of resonance was found to occur in certain ranges of the frequency and the amplitude of the magnetic field. Three types of oscillation patterns were observed, i.e., mode 1 with one node, mode 2 with two nodes and a peculiar oscillation between these modes. The frequencies of models 1 and 2 were twice that of the magnetic field, while the frequency of the peculiar oscillation was the same as that of the magnetic field.

Numerical Simulation of Oscillation of Single Spike of Magnetic Fluid under Vertical Alternating Magnetic Field.

A numerical simulation was made of the oscillation of a spike of a magnetic fluid droplet under a vertical alternating magnetic field, and the time-dependent changes of the droplet shape and the inner flow field were estimated. The resonance was found to occur when the timings of the changes of the magnetic field and the radial flow motion coincide. A peculiar oscillation occurs when an annular peak is formed exactly at the maximum of the magnetic held. The oscillation of mode 2 occurs in when the magnetic field becomes its maximum exactly before the formation of the annular peak. The oscillation of mode 1 occurs when the single peak is formed exactly at the maximum of the magnetic field.

Approximate Analysis of Oscillation of Single Spike of Magnetic Fluid under Vertical Alternating Magnetic Field.

An approximate analysis was made of the oscillation of a single spike of a magnetic fluid droplet under a vertical alternating magnetic field. The shape of the spike was assumed to be semiellipsoidal. Two resonances were found to occur, which corresponded to mode 1 and the peculiar oscillation observed in a previous experiment. The resonance frequencies of both oscillations decreased with the increase in both the amplitude of the magnetic field and the volume of the droplet.

STATISTICAL PROPERTIES OF SU(1,1) COHERENT STATES OF LIGHT AND ITS INFLUENCE ON DYNAMICAL BEHAVIORS OF THE ATOM

In this paper, we study the properties of two kinds of SU(1,1) coherent states of light with Bargman index k=1/4 and k=3/4 and show that they posses different quantum statistical properties. The atomic dynamical behavior in a two-photon Jaynes-Cummings model with initial SU(1,1)coherent state field are discussed. We show that the time evolution of atomic inversion displays peculiar periodic oscillation and pulse which are very different from coherent states of light.

Electrically Induced Shape Oscillation of Drops as a Means of Direct-Contact Heat Transfer Enhancement: Part 1—Drop Dynamics

The shape oscillation of liquid drops passing through an immiscible liquid medium subject to a low-frequency (1 ∼ 16 Hz) alternating electric field having a sinusoidal waveform has been studied experimentally with the intention of investigating the enhancement of the direct-contact heat exchange between the two liquids. We have found that the field can induce, depending on its frequency, not only the resonant oscillation of the second mode of the drops, but also another peculiar oscillation that is related to the resonant oscillation of the third mode superposed on the second-mode oscillation.