Phase Shift Of Wave Research Articles

Investigation of Phase Shift and Travel Time of Acoustic Waves in the Lower Solar Atmosphere Using Multiheight Velocities

We report and discuss the phase shift and phase travel time of low-frequency (ν < 5.0 mHz) acoustic waves estimated within the photosphere and photosphere–chromosphere interface regions, utilizing multiheight velocities in the quiet Sun. The bisector method has been employed to estimate seven height velocities in the photosphere within the Fe i 6173 Å line scan, while nine height velocities are estimated from the chromospheric Ca ii 8542 Å line scan observations obtained from the narrowband imager instrument installed on the Multi-Application Solar Telescope operational at the Udaipur Solar Observatory, India. Utilizing a fast Fourier transform at each pixel over the full field of view, phase shift and coherence have been estimated. The frequency and height-dependent phase shift integrated over the regions having an absolute line-of-sight magnetic field of less than 10 G indicates the nonevanescent nature of low-frequency acoustic waves within the photosphere and photosphere–chromosphere interface regions. Phase travel time estimated within the photosphere shows nonzero values, aligning with previous simulations and observations. Further, we report that the nonevanescent nature persists beyond the photosphere, encompassing the photospheric–chromospheric height range. We discuss possible factors contributing to the nonevanescent nature of low-frequency acoustic waves. Additionally, our observations reveal a downward propagation of high-frequency acoustic waves indicating refraction from higher layers in the solar atmosphere. This study contributes valuable insights into the understanding of the complex dynamics of acoustic waves within different lower solar atmospheric layers, shedding light on the nonevanescent nature and downward propagation of the acoustic waves.

A diagnostic method of radial electron density distribution based on microwave transmission of cylindrical plasma along multipath

Based on the multipath propagation phase shift of electromagnetic wave in cylindrical plasma, a method to obtain the radial electron density distribution of non-uniform cylindrical plasma is proposed in this paper. Focused lens antennas are used in multipath transmission distribution diagnosis (MTDD), where the propagation area in the plasma is approximately the size of the focal spot. The equivalent propagation thickness at each layer can be calculated for each path based on the propagation region and layer thickness. Combining with Fermat's shortest wavelength principle, electromagnetic waves propagate in a straight line between different layers. The phase shift caused by the propagation of electromagnetic waves in each layer, starting from the outermost layer, can obtain layer by layer electron density. To validate the MTDD method, multipath transmission propagation phase shift was simulated in CST, and the electron density distribution was obtained, which has a good agreement with the preset electron density. In addition, the MTDD method was applied to inductively coupled plasma, and the diagnostic results showed high agreement with the Langmuir probe results. The proposed MTDD method has higher spatial resolution than the transmission diagnosis method and can provide more precise plasma parameter information.

Thermo-hydraulic transport characteristics of non-Newtonian nanofluid flow through wavy channel: Influence of nanoparticle volume fraction and Prandtl number

The present study numerically investigates the thermal-hydraulic transport characteristics of non-Newtonian nanofluid flowing through the trapezoidal wavy channel. Constitutive behavior of non-Newtonian fluid was used to elucidate the power law model. The average Nusselt number, pressure drop, and performance factor are evaluated for varying volume concentration of nanoparticles (0 ≤ ϕ ≤ 0.04) and Prandtl number (Pr = 0.76, 1, 6.39, 20, 50, and 100) at different values of Reynold number (Re = 50 and 500), power index values (n = 0.5, 1, 1.5) and wave phase shift (θ = 0°, 90°and 180°). An increase in average Nusselt number and pressure drop was observed for increasing volume concentration of nanoparticles, Prandtl number, and Reynold number. At the same time, the performance factor decreases with an increase in ϕ, Pr, and Re. The heat transfer rate was observed to be more for shear thinning fluids than shear thickening fluids.

Flexible terahertz phase shifter for optically controlled polydimethylsiloxane-vanadium dioxide composite film

In the terahertz (THz) band, modulation research has become a focal point, with precise control of the phase shift of THz waves playing a pivotal role. In this study, we investigate the optical control of THz phase shift modulation in a polydimethylsiloxane (PDMS)-vanadium dioxide (VO2) flexible material using THz time-domain spectroscopy. Under the influence of an 808-nm continuous wave (CW) laser with power densities ranging from 0 to 2.74 W/cm2, the PDMS-VO2 flexible material exhibits significant phase shift modulation in the frequency range of 0.2 to 1.0 THz. The maximum optical-pumping phase shift reaches 0.27π rad at 1.0 THz in a composite material with a VO2 mass fraction of 5% and a thickness of 360 µm, and the amplitude transmittance from 0.2 THz to 1.0 THz exceeds 70%. Furthermore, the composite material exhibits good stability under at least 640 switching cycle times, as confirmed through repeatability tests. The proposed composite devices offer a new approach for more flexible phase shift modulation owing to the flexibility of the composite material and the non-contact and precise modulation of light control. Additionally, the stress-adjustable characteristics of flexible materials make them highly suitable for use in wearable THz modulators, highlighting their significant application potential.

Nonlinear tunneling of chirped similaritons in non-centrosymmetric waveguides with quadratic-cubic nonlinearity

The nonlinear tunneling of the optical similaritons through both dispersion and nonlinear barriers in a non-centrosymmetric waveguide exhibiting second- and third-order nonlinearity is studied. Within the framework of an inhomogeneous quadratic-cubic nonlinear Schrödinger equation with distributed group velocity dispersion, reciprocal of the group velocity, quadratic-cubic nonlinearity, and gain or loss, we demonstrate the existence of a rich variety of exact similariton solutions in the shape of bright, kink, anti-kink, W-shaped, and gray solutions. The results show that these self-similar waves involve certain control parameters in their amplitude, phase, width, and shift of the inverse group velocity, which enables us to control their evolution dynamics in the waveguide system through a suitable choice of these parameters. It is found that the parameter of reciprocal of the group velocity decides the phase shift and group velocity of these self-similar waves. Also, the stability of the solutions is discussed numerically. Results of this paper are helpful for enriching the similariton theory and understanding the dynamics of self-similar waves in systems with quadratic–cubic nonlinearities.

Reliable formulas for accurately determining the resonance and antiresonance frequencies of thin film bulk acoustic resonators

Expanding upon Lakin’s theory by considering the phase shift of the acoustic waves in the metallic layers, we have developed an impedance formula for a piezoelectric layer covered by a finite thickness of metal layers, enabling the precise determination of its resonant and anti-resonant frequencies. Compared to experimental data and 3D finite element simulations, our formula can accurately and quickly predict resonant, anti-resonant frequencies, and bandwidth across a wide range of piezoelectric and metallic layer thickness combinations.

Model-independent Way to Determine the Hubble Constant and the Curvature from the Phase Shift of Gravitational Waves with DECIGO

In this Letter, we propose a model-independent method to determine the Hubble constant and curvature simultaneously by taking advantage of the possibilities of future spaceborne gravitational-wave detector DECIGO in combination with the radio quasars as standard rulers. Similarly to the redshift drift in the electromagnetic domain, accelerating expansion of the Universe causes a characteristic phase correction to the gravitational waveform detectable by DECIGO. Hence, one would be able to extract the Hubble parameter H(z). This could be used to recover a distance–redshift relation supported by the data not relying on any specific cosmological model. Assuming the FLRW metric and using intermediate-luminosity radio quasars as standard rulers, one achieves an interesting opportunity to directly assess the H 0 and Ω k parameters. To test this method, we simulated a set of acceleration parameters achievable by future DECIGO. Based on the existing sample of 120 intermediate-luminosity radio quasars calibrated as standard rulers, we simulated much bigger samples of such standard rulers possible to obtain with very long baseline interferometry (VLBI). In the case of (N = 100) of radio quasars, which is the size of the currently available sample, the precision of the cosmological parameters determined would be σH0=2.74 km s−1 Mpc−1 and σΩk=0.175 . In the optimistic scenario (N = 1000) achievable by VLBI, the precision of H 0 would be improved to 1%, which is comparable to the result of σH0=0.54 km s−1 Mpc−1 from Planck 2018 TT, TE, EE+lowE+lensing data, and the precision of Ω k would be 0.050. Our results demonstrate that such combined analysis, possible in the future, could be helpful in solving the current cosmological issues concerning the Hubble tension and cosmic curvature tension.

Investigation of a Nonlinear XNOR Logic Gate Based on an Induced Nonlinear Phase Shift of Spin Waves

Introduction. Recent years have seen a growing interest in studying the nonlinear properties of spin waves. Nonlinear phenomena, such as envelope solitons, nonlinear frequency shifts of intense spin waves, and etc., have attracted particular attention. However, a number of important issues remain to be underexplored, including the problem of induced nonlinear phase shift of spin waves. The relevance of this problem is related to the need to develop spin-wave logic gates that could be controlled by changing the spin wave phase.Aim. To study a nonlinear XNOR logic gate whose operation is based on the induced nonlinear phase shift of a spin wave.Materials and methods. An original theory is used to simulate the frequency response of a nonlinear XNOR logic gate. The operating principle of the nonlinear XNOR logic gate is substantiated. The possibility of implementing the nonlinear XNOR logic gate in a circuit similar to a spin-wave Mach-Zehnder interferometer is experimentally demonstrated.Results. An experimental study of the induced nonlinear phase shift of operating signals incident on identical nonlinear spin-wave phase shifters located in the arms of the logic gate was carried out. It is shown that an increase in the pump signal power up to 60 mW, supplied to nonlinear phase shifters, changes the induced nonlinear phase shift of the operating signal by more than 180°. Hence, nonlinear phase shifters can be used for constructing spin-wave logic gates. In addition, the operating principle of a spin-wave logic gate was experimentally studied. It is shown that the XNOR logical function is implemented in the low-frequency part of the device’s frequency response characteristic.Conclusion. Numerical simulation of the characteristics of a nonlinear XNOR logic gate based on the Mach-Zehnder interferometer circuit was carried out. It is shown that its logical functions are implemented due to the effect of an induced nonlinear phase shift of spin waves in nonlinear phase shifters located in different arms of the logic gate.

On enhancing the noise-reduction performance of the acoustic lined duct utilizing the phase-modulating metasurface

This work proposes a noise-reduction structure that integrates phase-modulating metasurface (PMM) with acoustic liners (ALs) to enhance the narrow band absorption performance of a duct with relatively small length-diameter ratio. The PMM manipulates the wavefront by introducing different transmission phase shifts based on an array of Helmholtz resonators, so that the spinning wave within the duct can be generated. Compared with the plane wave, the generated spinning wave has a lower group velocity, which results in a greater traveling distance over the ALs in the duct. The optimization design is performed to determine the final structural parameters of the PMM, which is based on the predictions of the amplitude and phase shift of the acoustic wave at the outlet of the PMM using the theory of passive phased array. With the manipulation of the PMM, the incident plane wave is modulated into a spinning wave, and then enters into the acoustic liner duct (ALD), whose structural parameters are optimized by maximizing the transmission loss using the mode-matching technique. Finally, the noise-reduction performance of this combined structure is evaluated by numerical simulations in the presence of grazing flow. The results demonstrate that, compared with the traditional ALD, the proposed structure exhibits a significant increase in transmission loss within the considered frequency band, especially near the peak frequency of the narrow band noise.

Tunable asymmetric transmission of flexural waves in the dual-layer magnetoelastic metasurfaces by modulating magnetic field

In this paper, we have established a design of dual-layer magnetoelastic metasurfaces and achieved the tunable asymmetric transmission of flexural waves by modulating magnetic field. Relying on the adjustable phase shift of flexural waves with a full 2[Formula: see text] range by applied different magnetic fields, the asymmetric transmission of flexural waves (i.e., asymmetric refraction and asymmetric focusing) can be realized without altering the structure based on the generalized Snell’s law. The results show that the proposed magnetoelastic metasurfaces exhibit the asymmetric refraction of flexural waves with the tunable working frequencies and incident angles. In addition, the asymmetric focusing of flexural waves can also be modulated by adjusting magnetic loading. The proposed magnetoelastic metasurfaces can provide a new way for actively controlling the asymmetric transmission of elastic waves, further broadening the potential applications in the field of vibration control as a dynamic tunable diode.

Dynamic rate analysis for low frequency operation of chemical reactors

Periodic operation of chemical reactors can enhance reactant conversion and product selectivity. It is desirable to identify reaction kinetics and networks that may benefit from non-steady state operation and to quantify the extent of that enhancement without extensive computations. In this study, we describe a simple method to establish approximate functional dependencies of isothermal point reaction enhancement on dynamic and kinetic parameters during low frequency operation. Low frequency operation permits the use of steady state as opposed to transient conservation equations to identify limits of fractional rate enhancement. By approximating local dynamic rates as square waves modulating between two steady states, an analytical function can be derived from global rate expressions. The function relates fractional rate enhancement to concentration wave amplitudes, phase shifts, cyclic averages, duty cycles and reaction orders for one or more dynamically-fed reactants. We show that the method may be applied to predict integral conversion enhancement for ideal reactors. During integral operation, nonstoichiometric concentration waves may change phase through disproportionate consumption of reactants at wave maxima and minima, hence inverting waves out-of-phase (180°) from their initial waveform. This may cause local rate enhancement to transition to rate diminishment. Three experimental examples involving catalytic oxidations are described that illustrate selected theoretical aspects of the study.

Stratosphere‐Troposphere Coupling of Extreme Stratospheric Wave Activity in CMIP6 Models

AbstractExtreme stratospheric wave activity has been suggested to be connected to surface temperature anomalies, but some key processes are not well understood. Using observations, we show that the stratospheric events featuring weaker‐than‐normal wave activity are associated with increased North American (NA) cold extreme risks before and near the event onset, accompanied by less frequent atmospheric river (AR) events on the west coast of the United States. Strong stratospheric wave events, on the other hand, exhibit a tropospheric weather regime transition. They are preceded by NA warm anomalies and increased AR frequency over the west coast, followed by increased risks of NA cold extremes and north‐shifted ARs over the Atlantic. Moreover, these links between the stratosphere and troposphere are attributed to the vertical structure of wave coupling. Weak wave events show a wave structure of westward tilt with increasing altitudes, while strong wave events feature a shift from westward tilt to eastward tilt during their life cycle. This wave phase shift indicates vertical wave coupling and likely regional planetary wave reflection. Further examinations of CMIP6 models show that models with a degraded representation of stratospheric wave structure exhibit biases in the troposphere during strong wave events. Specifically, models with a stratospheric ridge weaker than the reanalysis exhibit a weaker tropospheric signal. Our findings suggest that the vertical coupling of extreme stratospheric wave activity should be evaluated in the model representation of stratosphere‐troposphere coupling.

Permeability enhancement related to the 2021 Mw 7.4 Maduo earthquake: Insights from water-level tidal response and multi-depth temperature observations

Permeability, which is an important property that controls the transportation processes in the shallow crust, is known to change during large earthquakes. Several studies have independently documented changes in permeability or groundwater motion through water level, streamflow, water temperature, and geochemical observations. In this study, we first compared water level data from three wells located in the Longmenshan Fault zone, where the 2008 Mw 7.9 Wenchuan earthquake occurred. We then analyzed the changes in aquifer permeability associated with the 2021 Mw 7.4 Maduo earthquake, which occurred 640 km away from the study area, using water-level tidal response and multi-depth temperature observations from one of the three wells. Tidal response analysis of water-level data indicated a great increase in the phase shift of the M2 wave from negative to positive, reflecting an enhancement in vertical permeability of the aquifer due to the Maduo earthquake. Multi-depth temperature observations indicated that the co-seismic water temperature increased successively from deeper to shallower depths, indicating the upward migration of the water (at a transient rate of 1.5–2.3 × 10−2 m/s) in observation section. The results indicated that our method is effective for studying changes in the permeability of groundwater motion in an aquifer related to an earthquake.

Analysis of the error of influencing factors on the result of measuring the moisture content of grain and grain products

The potential to utilize an ultrahigh-frequency method to regulate the humidity of grain and the products of their industrial processing, allowing one to use this method to regulate technological processes in the production environments of grain-processing industries by controlling the material under examination in free space and converting the measured parameters of the electromagnetic wave passed through the material into an electrical signal. The developed functional scheme of the experimental setup based on the ultrahigh-frequency method of dependence of attenuation and phase shift of electromagnetic wave on the volumetric density of wheat grain at different mass fraction of humidity is discussed, it is shown that with increasing volumetric density at a constant value of the mass fraction of moisture decreases the error of grain moisture measurement with increasing volumetric density, where the main component of the total error of the ultrahigh frequency method (amplitude and phase) is associated with the influence of interfering factors and depends mainly on the variable thickness and density of the controlled material. In order to reduce the components of measurement error brought on by various non-informative (interfering factors) parameters on the outcome of measuring the mass moisture ratio of grain and grain products, the method of moisture measurement in both discrete and inline manufacturing is investigated.

Nonzero Phase Shifts of Acoustic Waves in the Lower Solar Atmosphere Measured from Realistic Simulations and Their Role in Local Helioseismology* *Current Version: 0.00.

Previous studies analyzing the evanescent nature of acoustic waves in the lower solar atmosphere, up to 300 km above the photosphere, have shown an unexpected phase shift of an order of 1 s between different heights. Those studies investigated the spectral line Fe i λ6173.3, commonly used for helioseismic measurements. Such phase shifts can contribute to a misinterpretation of the measured travel times in local helioseismology, complicating inferences of, e.g., the deep meridional flow. In this study, we carry out phase shift computations using a simulated, fully radiative, and convective atmosphere from which the Fe i λ6173.3 line is synthesized. The resulting phase shifts as functions of frequency across multiple heights show nonzero values in evanescent waves, similar to what was found in observational data. Comparing the Doppler velocities estimated from the synthesized absorption line with the true velocities directly obtained from the simulated plasma motions, we find substantial differences in phase shifts between the two. This leads us to hypothesize that the nonadiabaticity of the solar atmosphere yields extra phase shift contributions to Doppler velocities. Finally, computing phase differences for different viewing angles reveals a systematic center-to-limb variation, similar to what is present in observations. Overall, this study helps to improve our understanding of the physical cause of the helioseismic center-to-limb effect.

Nonlinear phase shifts induced by pumping spin waves in magnonic crystals

A nonlinear phase shift of low-power spin waves (SWs) induced by a high-power pumping SW excited both inside and outside the magnonic band-gaps of a magnonic crystal has been studied. The magnonic crystal with spatially periodic thickness is fabricated from an yttrium iron garnet film by chemical etching. The results show that the phase shift of the low-power SWs can be effectively controlled by variation of power level of the pumping SW. This induced nonlinear phase shift is weakened if the pump frequency lies in the magnonic bandgap. The data obtained are well explained by contradirectional coupling of the high-power forward and reflected spin waves. A theoretical model for this effect is presented. Our findings are important for the further progress in SW computing.

Influence of Stationary Waves on Precipitation Change in North American Summer during the Last Glacial Maximum

Abstract Paleo-proxy reconstructions reveal a moistening of the American Southwest during the Last Glacial Maximum (LGM; 21 ka). However, the primary mechanisms driving the moistening trend are still debated, with relatively few studies focused on hypotheses related to synoptic changes in precipitation. Analysis of the Paleoclimate Intercomparison Model Project (PMIP3) simulations shows enhancement of precipitation in the southwest and south-central United States during the winter and summer. Here, we suggest that summertime eastward phase shifting of stationary waves at the LGM enhanced precipitation in the south-central United States and dried the southeastern United States. Mechanism denial experiments performed with version 3 of the Hadley Centre Coupled Model (HadCM3) indicate that the thermodynamic effect of the Laurentide Ice Sheet forced eastward phase shifting of stationary waves. By comparing a synthesis of LGM proxies to the PMIP3 ensemble, we find models that compare more favorably to the reconstructions simulate a weaker Laurentide ice thermodynamic effect, smaller eastward phase shifting of stationary waves, and weaker jet stream anomalies. Significance Statement Our study is motivated by the impact of climate change on hydroclimate in North America, especially in the semiarid areas near the southwestern United States, and the persistent problem of significant disagreements among CMIP model projections. Yet modern models and observations alone cannot tell us the likeliest climate change outcome in this region. Here we analyze precipitation during the LGM reconstructed from proxies and as simulated by the PMIP3, which reveal a precipitation trend with wetting in the southwestern United States and drying in the southeastern United States. Our interpretation of the PMIP3 simulations involves application of simple theories for midlatitude stationary waves, and indicates that the LGM precipitation is generated by the phase shift of stationary waves from the enhancement of jet speeds. Our model–data comparison also suggests that in the PMIP3 simulations, weak LGM jet stream anomalies, due to weak polar amplification, compare more favorably to the proxies.

Study of X(6900) with unitarized coupled channel scattering amplitudes

In this paper, we study the resonant state X(6900). The scattering amplitudes of coupled channels, J/psi J/psi -J/psi psi (2S)-J/psi psi (3770), are constructed with the interaction of four vector mesons described by effective Lagrangians. The amplitudes are calculated up to one loop, decomposed by partial wave projection, and unitarized by Padacute{e} approximation. These amplitudes are fitted to the latest experimental data sets of di-J/psi and J/psi psi (2S) invariant mass spectra of LHCb, CMS, and ATLAS. High-quality solutions are obtained. With these partial wave amplitudes, we extract the pole parameters of the X(6900). Its quantum number is likely to be 0^{++}. According to the pole counting rule as well as analysis of the phase shifts of the partial waves, it supports our previous conclusion that the X(6900) prefers to be a compact tetra-quark.

Traveling Wave Solutions and Conservation Laws of a Generalized Chaffee–Infante Equation in (1+3) Dimensions

This paper aims to analyze a generalized Chaffee–Infante equation with power-law nonlinearity in (1+3) dimensions. Ansatz methods are utilized to provide topological and non-topological soliton solutions. Soliton solutions to nonlinear evolution equations have several practical applications, including plasma physics and the diffusion process, which is why they are becoming important. Additionally, it is shown that for certain values of the parameters, the power-law nonlinearity Chaffee–Infante equation allows solitons solutions. The requirements and restrictions for soliton solutions are also mentioned. Conservation laws are derived for the aforementioned equation. In order to comprehend the dynamics of the underlying model, we graphically show the secured findings. Hirota’s perturbation method is included in the multiple exp-function technique that results in multiple wave solutions that contain new general wave frequencies and phase shifts.

Elastic scattering of positive muons from He3 and He4

The study of positive muon ${\ensuremath{\mu}}^{+}$-He scattering plays an important role in precision experiments involving positive muons. In this paper, we employed the confined variational method to investigate $S$-wave ${\ensuremath{\mu}}^{+}$-He scattering with scattering momenta below $0.1{a}_{0}^{\ensuremath{-}1}$, where ${a}_{0}$ denotes the Bohr radius. Our approach yielded accurate $S$-wave phase shifts and scattering lengths. By utilizing the modified effective range formula, we determined the $S$-wave scattering lengths to be $\ensuremath{-}12.3{a}_{0}$ and $\ensuremath{-}10.6{a}_{0}$ for ${\ensuremath{\mu}}^{+}\text{\ensuremath{-}}^{4}\mathrm{He}$ and ${\ensuremath{\mu}}^{+}\text{\ensuremath{-}}^{3}\mathrm{He}$ scattering, respectively. Furthermore, we examined the distortion effects on helium induced by ${\ensuremath{\mu}}^{+}$.