Ocean internal waves interpreted as oscillation travelling waves in consideration of ocean dissipation

Most studies of the synthetic aperture radar remote sensing of ocean internal waves are based on the solitary wave solutions of the Korteweg-de Vries （KdV） equation, and the dissipative term in the KdV equation is not taken into account. However, the dissipative term is very important, both in the synthetic aperture radar images and in ocean models. In this paper, the traveling-wave structure to characterize the ocean internal wave phenomenon is modeled, the results of numerical experiments are advanced, and a theoretical hypothesis of the traveling wave to retrieve the ocean internal wave parameters in the synthetic aperture radar images is introduced.     

Theory of finite-amplitude standing waves

A new approach to the theory of finite-amplitude standingwaves in proposed,and foumulas of steady wave forms are derived fromthe fundamental equations of hydrodynamios,as an endeavor to settle thelong-time disputable situation.     

Spin waves in magnetic Weyl semimetals

Intrinsic magnetic topological materials,namely the stoichiometric magnetic compounds possessing both inherent magnetic order and topological electronic states,have attracted tremendous interest in the research of condensed matter physics and materials science[1].Such materials not only bring new opportunities to realize many exotic topological phenomena under time-reversal symmetry breaking,but also show great potential in applications of quantum technology[2].     

Non-Hermitian topological coupler for elastic waves

Non-Hermitian topological systems,by combining the advantages of topological robustness and sensitivity induced by nonHermiticity,have recently emerged and attracted much research interest.Here,we propose a device based on the topological coupler in elastic waves with non-Hermiticity,which contains two topological domain walls and four ports.In this device,topological robustness routes the transmission of waves,while non-Hermiticity controls the gain or loss of waves as they propagate.These mechanisms result in continuous and quantitative control of the energy distribution ratio of each port.A nonHermitian Hamiltonian is introduced to reveal the coupling mechanism of the topological coupler,and a scattering matrix is proposed to predict the energy distribution ratio of each port.The proposed topological coupler,which provides a new paradigm for the non-Hermitian topological systems,can be employed as a sensitive beam splitter or a coupler switch.Moreover,the topological coupler has potential applications in information processing and logic operation in elastic circuits or networks,and the paradigm also applies to other classical systems.     

Saturation functions of non-linear standing waves

1IntroductionItwasfoundthatalltheharmonicsofanon-linearstandingwaveexhibitsaturationten-dency'esPeciallysignificalltasthefundamentalsoundpressureisraisedoverl5odBre2OpPaor'so,andtheexperimentallawofsaturationwasobtainedbycurve-fittingll].Theformulasobtainedagreedwellwiththeexperimentaldata,within1dBinthewholerange.Theexper-imeotswerecarriedonfundamelltalfrequencies22OHz,294Hzand366Hz,thethird,fourthandforhresonancefrequenciesoftheclosedtube,respectively,denotedbym=3,tn=4,andm=5.Theorderoft…     

Are rogue waves robust against perturbations?

We study the effect of various perturbations on the fundamental rational solution of the nonlinear Schrödinger equation (NLSE). This solution describes generic nonlinear wave phenomena in the deep ocean, including the notorious rogue waves. It also describes light pulses in optical fibres. We find that the solution can survive at least three types of perturbations that are often used in the physics of nonlinear waves. We show that the rational solution remains rational and localized in each direction, thus representing a modified rogue wave.     

Sliding charge density waves in manganites?

We report on the linear and nonlinear conductivity measurements on charge-ordered La_1?xCa_xMnO₃ (x≈0.5 and x=0.75). Upon cooling below room temperature, the onset of charge ordering—T_co is marked by a peak in the logarithmic derivative of the resistivity (d ln ρ/d(1/T)) and by a change in the slope of the thermopower as a function of temperature. The I–V characteristics of samples with negative coefficient of resistivity (x=0.52 and 0.75) was measured by DC and pulsed currents. We show how the nonlinearity of the I–V characteristics vanishes when short, single current pulses are used. This work shows that when searching for dramatic phenomena such as sliding charge density waves in samples with negative temperature coefficient of resistivity, the first step should be to check if the I–V nonlinearity persists when using single, short current pulses.     

Weyl monopoles dance with the spin waves

In a Weyl semimetal(WSM),the conduction and valence bands cross each other near the Fermi energy,and the crossing points,called Weyl points,exhibit a monopole-like distribution of the Berry curvature.The Berry curvature is a fictitious magnetic field in the momentum-space and induces the anomalous velocity to the real-space electron motion.Therefore,Weyl monopoles play essential roles in the charge transport,for example,the anomalous Hall effect(AHE).The anomalous Hall conductivity(AHC)is nearly proportional to the distance between the Weyl point pairs with opposite chirality.The magnetic order and spin structure sensitively modify Weyl point positions and energies.     

Electromagnetic waves in the Kerr–Schild metric

A short electromagnetic wavelength approximation is used to obtain general solutions to the Maxwell equations for electromagnetic radiation in a Kerr–Schild plane gravitational wave metric. Their properties are then investigated for the specific case of a light beam in a weak, harmonic gravitational wave.     

An experiment to detect “empty” waves

An experiment has been conducted to test the speculation that empty waves suffer attenuation in their propagation relative to waves which carry singularities. This speculation leads to the prediction that the contrast of interference fringes should decrease exponentially with free independent path length. A double-slit experiment has been carried out in which the distance between the slits and the observation plane has been varied over a wide range. High contrast interference fringes have been recorded and the contrast measured as a function of distance between the slits and the observation plane. No convincing evidence is found for attentuated empty waves.     

Controllability of shock waves in one-dimensional polariton condensates

In one-dimensional incoherent pumped exciton–polariton condensates, we realize the generation and control of supersonic shock waves. By choosing a suitable initial input wave, we obtain the region of existence of various shock waves as a function of the phase of the initial wave, the coefficient of polariton interaction, the coefficient of the interaction between polariton and reservoir and the condensation rate and intensity of pumping. Using these results, we discuss the effect of different pa...     

Propagation of Lamb waves in pure longitudinal modes

I.IntroductionSinceLambwaveshavewideaPplicationinnondestructiveinspectionandsensors1interestsintheinvestigationofit8propagationaredeveloped.VictorovI1lhaspointedoutthatastohomogeneous,whformsolidplateinunersedillliquld,theverticaldisplacementoftheplate'ssurfaCemaybezerowhenthephasevelocityisequaltotheplatelongitudinalwavespeed.ThisconclusionhasimportantaPplication.RecelltlyPilaskietc.I2]aPproveditbyusing.thefree-boundaryLambwavtheoryandgavetheconditionstoreachit.ItisknownthatthedisaPpeara…     

Are there waves in elastic wave turbulence?

An thin elastic steel plate is excited with a vibrator and its local velocity displays a turbulentlike Fourier spectrum. This system is believed to develop elastic wave turbulence. We analyze here the motion of the plate with a two-point measurement in order to check, in our real system, a few hypotheses required for the Zakharov theory of weak turbulence to apply. We show that the motion of the plate is indeed a superposition of bending waves following the theoretical dispersion relation of the linear wave equation. The nonlinearities seem to efficiently break the coherence of the waves so that no modal structure is observed. Several hypotheses of the weak turbulence theory seem to be verified, but nevertheless the theoretical predictions for the wave spectrum are not verified experimentally.     

Theoretical investigation of laser-generated guided waves in hollow cylinders

IIntroductlon Corroslon and pitting defects In plpework are major problems In the oil,gajs,chemicaland other Industries.They m叫 lead to serious consequences lfthey would not be detected Intime.Although the ultrasonic nondestructlve testing technique and lash radlography methodhave been used In steel Industry tor the postproductlon Inspection of tubing,these traditionalmethods or techniques are Inefficient and prohlbltlvely expensive It Is obviously unpractical toInspect of pipe;which Is …     

Radio waves and γ-ray emission from astrophysical sources

A mechanism of X- and γ-ray emission by relativistic electrons at interaction with astrophysical objects (maser clouds) is considered and the contribution of this mechanism to the formation of a continuous spectrum and its correlation with radio-wave radiation are investigated. The radiation yield upon deexcitation of a quantum system by an electron exceeds that of “conventional” (i.e., without a change in the quantum-system state) bremsstrahlung at small nuclear charges (Z < 10) and may be about 8% of the total γ-ray intensity. It is shown that in the direction in which the γ-ray intensity increases, one should observe radio waves corresponding to a particular maser source.     

Magnetically tunable Airy-like beam of magnetostatic surface spin waves

In this Letter,we report an Airy-like beam of magnetostatic surface spin wave(Ai BMSSW)supported on the ferromagnetic film,which is transferred from the optical field.The propagation properties of Ai BMSSW were verified with micromagnetic simulation.From simulation results,the typical parabolic trajectory of the Airy-type beam was observed with an exciting source encoding 3/2 phase pattern.The simulation results coincide well with design parameters.Furthermore,simulated results showed that the trajectories of the Ai BMSSW could be tuned readily with varied external magnetic fields.This work can extend the application scenario of spin waves.