Effective Propagation Distance Research Articles

Understanding the thermal effect of power ultrasound in cement paste

The thermal effect of power ultrasound (PUS) converts acoustic energy into heat energy and promotes cement hydration, whereas the effective propagation distance and mechanisms are poorly understood. This study employed two distinct water-to-cement (w/c) ratios, specifically w/c = 0.30 and 0.50, in conjunction with four ultrasound power levels (0 W, 100 W, 450 W and 900 W) and four varying durations of ultrasound irradiation (0 min, 3 min, 10 min and 30 min), as independent variables. The temperature–time (T-t) curves of cement paste under different treatment conditions were recorded and analyzed. The improved heat evolution model was used to analyze cement hydration evolution at the sonication stage. The results indicated that the effective ultrasonic distance corresponding to significant temperature elevation was below 100 mm. Additionally, the hydration degree of cement paste showed a conspicuous gradient characteristic when subjected to ultrasonic irradiation. Applying 900 W ultrasound irradiation for 10 min resulted in a more homogeneous temperature field compared to the other experimental groups. This work provides the potential of employing the thermal effect for prestressed cement panels.

Dynamic modeling and load transfer prediction of drill-string axial vibration in horizontal well drilling

A three-dimensional finite element dynamics model of drill-string is established considering dynamic friction model and buckling effect. The modified dynamics model is proved to have higher computational accuracy by laboratory experiment. A parameters study is conducted based on the dynamics model. Results show that the exciting force amplitude, drilling fluid density, axial force, friction coefficient, and drill-string dimension have significant effects on the friction reduction performance and effective propagation distance of axial vibration. A prediction model for vibration propagation distance is established, which facilitates efficient optimization of the axial vibration parameters in horizontal well drilling. This study can provide theoretical guidance for axial vibration to safely and efficiently reduce the sliding friction in exploitation of unconventional oil-gas reservoirs.

Idealized four-wave mixing dynamics in a nonlinear Schrödinger equation fiber system

The observation of ideal four-wave mixing dynamics is notoriously difficult to implement experimentally due to the generation of higher-order sidebands and optical loss, which limit the potential interaction distance. Here, we overcome this problem with an experimental technique that uses programmable phase and amplitude shaping to iterate the wave mixing initial conditions injected into an optical fiber. This extends the effective propagation distance by two orders of magnitude, allowing idealized Kerr-driven dynamics to be seen over 50 km of fiber using only one short fiber segment of 500 m. Our experiments reveal the full phase space topology, showing characteristic features of multiple Fermi–Pasta–Ulam recurrence, stationary wave existence, and the system separatrix representing the boundary between two distinct regimes of spatiotemporal evolution. Experiments are in excellent quantitative agreement with numerical solutions of the differential equation system describing the wave evolution. This experimental approach can be readily adapted to study other wave mixing and nonlinear propagation phenomena in optics.

Acoustic Bessel Vortex Beam by Quasi-Three-Dimensional Reflected Metasurfaces.

Vortex beams have a typical characteristic of orbital angular momentum, which provides a new degree of freedom for information processing in remote communication and a form of non-contact manipulation for trapping particles. In acoustics, vortex beams are generally observed on the surface of a metamaterial structure or in a waveguide with a hard boundary owing to the characteristic of easy diffusion in free space. The realization of an acoustic vortex beam with a long-distance propagation in free space still remains a challenge. To overcome this, we report a type of acoustic Bessel vortex (ABV) beam created by a quasi-three-dimensional reflected metasurface in free space based on phase modulation. By using the Bessel and vortex phase profiles, we can realize an ABV beam with the high performances of both Bessel and vortex beams, and its effective propagation distance is larger than 9.2λ in free space. Beyond that, we discuss the bandwidth and topological charge of the ABV beam in detail, and the fractional bandwidth can reach about 0.28. The proposed ABV beam has the advantages of a high-performance vortex, long-distance propagation, and broad bandwidth, which provide a new pathway for designing multifunctional vortex devices with promising applications.

Experimental Research and Numerical Analysis of the Attenuation Law of Ultrasound Propagating in Shale

To study ultrasound’s attenuation law propagating in shale, we first tested the attenuation rate of ultrasound in air and shale by assembling an experimental device by ourselves. The experimentally measured ultrasonic attenuation coefficient in the air is close to the value obtained from most kinds of literature, so our self-assembled practical device is very reliable. By fitting the experimental data, we found that the average attenuation coefficient of ultrasound in the air is 0.0258 dB/m. The average attenuation coefficient in shale is 0.0657 dB/m. As the ultrasonic power increases, the attenuation coefficient of ultrasound gradually increases. Through calculation and analysis using the ultrasonic intensity formula, we found that the effective propagation distance of ultrasound in shale is about 1.2 m.

Spin waves excitation at micron-sized, anisotropy modified regions in amorphous Fe80B20 stripes: Local properties and inter-regions coupling

We report on the measurement of the local magnetization dynamics occurring, at units of GHz, in large aspect ratio stripes lithographed from reduced damping amorphous Fe80B20 films. The stripes were submitted to local anisotropy modifications by micrometric beam synchrotron X-ray irradiation. Our results include data on the dispersion relationships and group velocities corresponding to spin waves excited at both the non-irradiated and the irradiated regions. Whereas in the former case we observed standing spin waves with transverse-to-the stripe axis wave vector, in the latter one, for which the wave vector of the spin waves was parallel-to-the stripe axis, propagating spin waves were excited. In both regions, we measured the effective propagation distance of the spin waves, which resulted to be independent of the wave vector orientation. In the spin waves excited at the irradiated region, we also measured the decay time and effective damping coefficient, which was in good agreement with previously reported values obtained from FMR measurements in amorphous Fe80B20 continuous films. We show that the interaction of the non-irradiated and irradiated zones results, at the stripe transverse saturation remanence and under an exciting field frequency of 4 GHz, in the introduction of a π phase shift between the standing spin waves excited at both sides of the irradiated region. This result opens the possibility of using the local, transverse to the stripe axis, magnetic anisotropy easy axis induced by the X-ray irradiation as a crucial constituent of a zero-applied field spin wave phase-shifter.

Low Threshold and Long‐Range Propagation Plasmonic Nanolaser Enhanced by Black Phosphorus Nanosheets

AbstractThis work theoretically proposes a novel surface plasmon polaritons nanolaser enhanced by 2D black phosphorus (BP) nanosheets, which can greatly enhance the local electric field and reduce the normalized mode area. The plasmonic nanolaser is created by integrating few‐layered BP nanosheets into a hybrid waveguide structure consisting of a cadmium sulfide (CdS) semiconductor nanowire, a low‐index dielectric MgF2 buffer film, and a silver substrate. Both the electric field distribution and mode parameters originating from the proposed hybrid structure are systematically studied. The simulation results show that, under the optimal conditions with r = 95 nm, hgap = 2 nm, and d = 1 nm, three key mode parameters (effective mode area, gain threshold, and propagation distance) can be determined to be 0.008 λ2, 0.5997 µm−1, and 3309 nm, respectively. Moreover, the figure of merit of the proposed nanolaser is enhanced by almost 2.3 times compared with the model without BP nanosheets. It can be expected that the proposed plasmonic nanolaser shows great potential in exploring ultrahigh density photonic integrated circuit.

A flexible numerical calculation method of angular spectrum based on matrix product.

Fast Fourier transform (FFT) is the most commonly used mathematical method in numerical calculation, and the FFT-based angular spectrum method (ASM) is also used widely in diffraction calculation. However, the frequency and spatial sampling rules in FFT limit the effective propagation distance and the observation window range of ASM. A novel method for calculating the angular spectrum based on the matrix product is proposed in this Letter. This method realizes the fast calculation of discrete Fourier transform (DFT) based on the matrix product, in which the sampling matrix is orthogonally decomposed into two vectors. Instead of FFT, angular spectrum diffraction calculation is carried out based on the matrix product, which is named the matrix product ASM. The method in this Letter uses a simple mathematical transformation to achieve maximum compression of the sampling interval in the frequency domain, which significantly increases the effective propagation distance of the angular spectrum. Additionally, the size of the observation window can be enlarged to obtain a wider calculation range by changing the spatial sampling of the output plane.

Plasma density profile measurements for ultra-short high power laser beam guiding experiments at SPARC _LAB

External injection is a promising method to achieve high accelerating gradients and to control the beam properties. The energy gain of an electron via the wakefield is proportional to the product of the accelerating field multiplied by the effective propagation distance of the laser. Therefore, in order to bring the electron energy in the order of the GeV, a longer propagation length is required, which can be obtained by guiding the laser pulse in a wave-guide. In the case of SPARC_LAB, a 500 μτη diameter hydrogen-filled capillary discharge is used; to guide the laser beam it is necessary to act on the refractive index of the plasma, depending on its density. In this work measurements of the trend over time of the longitudinal profile of the plasma density within the capillary are presented, along with openFOAM simulations of the gas profile distribution. Preliminary test of laser guiding are also shown, detecting the behaviour of the laser beam at the exit of the capillary with respect to the discharge current value.

Controllable excitations of rogue waves and breathers in an inhomogeneous erbium doped fiber system

We study the generalized nonlinear Schrödinger Maxwell–Bloch equation describing wave propagation in erbium-doped nonlinear fibers and derive the analytical bright and dark rogue wave and breather solutions under certain parametric conditions. We display the propagation properties of the attained solutions by modulating the relation between maximum effective propagation distance ζm and the parameter ζ0 relating to the excitation type of nonlinear waves. Their controllable behaviors such as fast appearance, postponement, sustainment and annihilation for exponentially dispersion decreasing fiber system have been demonstrated. Additionally, we delineate the longitudinal control of rogue waves. Our results may be useful in understanding and enriching the manipulation of rogue waves in resonant erbium-doped optical fibers.

Asymmetries in adaptive optics point spread functions

An explanation for the origin of asymmetry along the preferential axis of the point spread function (PSF) of an AO system is developed. When phase errors from high-altitude turbulence scintillate due to Fresnel propagation, wavefront amplitude errors may be spatially offset from residual phase errors. These correlated errors appear as asymmetry in the image plane under the Fraunhofer condition. In an analytic model with an open-loop AO system, the strength of the asymmetry is calculated for a single mode of phase aberration, which generalizes to two dimensions under a Fourier decomposition of the complex illumination. Other parameters included are the spatial offset of the AO correction, which is the wind velocity in the frozen flow regime multiplied by the effective AO time delay and propagation distance or altitude of the turbulent layer. In this model, the asymmetry is strongest when the wind is slow and nearest to the coronagraphic mask when the turbulent layer is far away, such as when the telescope is pointing low toward the horizon. A great emphasis is made about the fact that the brighter asymmetric lobe of the PSF points in the opposite direction as the wind, which is consistent analytically with the clarification that the image plane electric field distribution is actually the inverse Fourier transform of the aperture plane. Validation of this understanding is made with observations taken from the Gemini Planet Imager, as well as being reproducible in end-to-end AO simulations.

Unidirectional launching and elongating propagation of airy surface plasmon polaritons by a metasurface coupling grating

Plasmonic metasurfaces can be used to control light wavefronts with subwavelength resolution by introducing spatial variations in the optical response of metallic antennas. Here, by taking advantage of Airy surface plasmon polaritons (Airy SPPs) with an ultralong effective propagation distance, we change their coupling grating structures into their plasmonic metasurface analogues, i.e., we introduce T-shaped nano-slits as geometric phase units to replace the conventional grating. Through the metasurface coupling grating, the propagation direction of Airy SPPs can be controlled by selecting the polarization of the excitation light. Furthermore, constructive interference effect occurs by controlling the meeting between two Airy SPPs in two structures, which continues to elongate their effective propagation distance. Effectively exploiting SPP energy and manipulating its propagation could pave the way for ultra-efficient flat optical devices.

Excitation manipulation of three-dimensional completely localized rogue waves in a partially nonlocal and inhomogeneous nonlinear medium

We study a (2 + 1)-dimensional variable-coefficient-coupled partially nonlocal nonlinear Schrodinger equation with nonlinearities localized in x and y-directions and non-localized in z-direction, and set up a one-to-one connection between it and the standard nonlinear Schrodinger equation. Using this one-to-one connection, and with the help of bilinear method, we analytically derive first-order and second-order rogue wave solutions including rogue wave triplet solution, which are completely localized in three-dimensional space. By modulating the maximal value of the effective propagation distance, and comparing this maximal value with the top (peak) position of rogue wave excitation in the exponential diffraction decreasing system, we discuss the excitation manipulation of three-dimensional rogue waves, including original excitation, top excitation, tail excitation and fast complete excitation of single rogue wave and rogue wave triplet.

Excitation management of (2+1)-dimensional breathers for a coupled partially nonlocal nonlinear Schrödinger equation with variable coefficients

The Akhmediev-breather and Ma-breather solutions of a (2+1)-dimensional variable-coefficient coupled partially nonlocal nonlinear Schrodinger equation with non-localized in y-direction nonlinearities and localized in x and z directions are constructed. From these solutions, the excitation management of (2+1)-dimensional breathers including the complete excitation, rear excitation, peak excitation and initial excitation is studied via the comparison of values between the maximum value of effective propagation distance and the location of peak in breathers.

Generalization of Wolf effect of light on arbitrary two-dimensional surface of revolution

Investigation of physics on two-dimensional curved surface has significant meaning in study of general relativity, inasmuch as its realizability in experimental analogy and verification of faint gravitational effects in laboratory. Several phenomena about dynamics of particles and electromagnetic waves have been explored on curved surfaces. Here we consider Wolf effect, a phenomenon of spectral shift due to the fluctuating nature of light fields, on an arbitrary surface of revolution (SOR). The general expression of the propagation of partially coherent beams propagating on arbitrary SOR is derived and the corresponding evolution of light spectrum is also obtained. We investigate the extra influence of surface topology on spectral shift by defining two quantities, effective propagation distance and effective transverse distance, and compare them with longitudinal and transverse proper lengths. Spectral shift is accelerated when the defined effective quantities are greater than real proper lengths, and vice versa. We also employ some typical SORs, cylindrical surfaces, conical surfaces, SORs generated by power function and periodic peanut-shell shapes, as examples to provide concrete analyses. This work generalizes the research of Wolf effect to arbitrary SORs, and provides a universal method for analyzing properties of propagation compared with that in flat space for any SOR whose topology is known.

Excitation control for three-dimensional Peregrine solution and combined breather of a partially nonlocal variable-coefficient nonlinear Schrödinger equation

A (2 + 1)-dimensional variable-coefficient partially nonlocal nonlinear Schrodinger equation is considered, and analytical Peregrine solution (PS) and combined Akhmediev breather (AB) are presented from a reduced transformation and the Darboux transformation method. Based on these analytical solutions, the excitation control for three-dimensional PS and combined AB is investigated by comparing values between the maximum value of the effective propagation distance $$\zeta _{\max }$$ and the crest position $$\zeta _{0}$$ (for the first-order PS and second-order PS) or the crest position $$\zeta _n(n=1,2,3)$$ (for the combined AB). If $$\zeta _{\max } \zeta _{0}$$, the anterior excitation, crest excitation, and tail excitation of the first-order PS and second-order PS can be studied, respectively. Similarly, if $$\zeta _{\max } \zeta _{n}$$, the anterior excitation, crest excitation, and tail excitation of the first first-order PS, the second-order PS and the second first-order PS in the combined AB can be discussed, respectively. The $$k+1$$-layer excited structures for the first-order PS, second-order PS, and the combined AB can be constructed for the fixed value of the Hermite polynomial parameter k.

Enhancement of Phase-Shifting Nonreciprocity in Metamaterial Lines With Comb-Shaped Capacitive Stubs on the Normally Magnetized Ferrite Substrate

In this paper, enhancement of phase-shifting nonreciprocity is proposed by using metamaterial lines with comb-shaped capacitive stubs on the normally magnetized ferrite substrate. The insertion of capacitive stubs enhances the effective permittivity, i.e., effective propagation distance in one propagation direction due to edge-guided mode propagation along the comb-shaped stub edges. The nonreciprocity of the proposed structure was numerically compared with those of other types of metamaterial lines, and transmission characteristics of the prototype circuit were measured and reproduced by the numerical simulations, verifying the enhancement.

Generation of coupled radio frequency orbital angular momentum beam with an optical-controlled circular antenna array

A circular antenna array (CAA) principle for generating radio frequency orbital angular momentum (RF-OAM) beams with dual-opposite-states is proposed in an optical-controlled system. At this condition, the pre-existing restrictions of antenna amount for CAA system is extended. It is worth noting that the simulative beam patterns show almost no distortion in this superposition states case. In the following control experiment, transmission characteristics, including Error Vector Magnitude (EVM), Signal to Noise Ratio (SNR) and receiving power, are all improved significantly in each proposed coupled OAM channel, compared to ones in single-state OAM beam. The EVM can be decreased from 4.82% to 4.59% in average, and the receiving power is increased by 2.7 dB at the same transmission condition, which indicates effective propagation distance can be increased.

Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

Review of Wireless Personal Communications Radio Propagation Models in High Altitude Mountainous Areas at 2.6 GHz

This paper presents five commonly used radio propagation models (RPMs) which are suitable for the prediction of path loss in macrocell environments of LTE wireless communication systems. These RPMs’ application in high altitude mountainous areas networks (HAMANETs) environment requires further validation and studies. Through using the measured path loss in the HAMANETs at 2.6 GHz to calculate the predicted value of the five RPMs and the measured value’s mean error (ME), root mean square error, and error standard deviation (ESTD), we verified the predicted value of the SPM model that is closer to the actual measurement. On this basis, the empirical propagation model in HAMANETs environment is corrected. When correcting, a method to calculate base station’s effective antenna height and propagation distance is provided by using the altitude above sea level data. This method can reduce the error that the mountainous areas are simplified to the flat-terrain in the existed propagation models. A linear least square method is used to calculate the optimal propagation model. Finally, the ME is the smallest, and the ESTD is less than 8 dB, which indicate that the corrected propagation model is more suitable for the actual environmental path loss’s prediction. The results show that the path loss factor of the test area is about 65 dB, including the influence of the high altitude, mountains, vegetation, and air humidity in HAMANETs environment. The study results can provide useful advice to the evaluation and verification of personal wireless communications in the HAMANETs. Furthermore, using the correction method proposed in this paper can correct propagation models suitable for the different propagation environments to improve the accuracy and efficiency of wireless network optimization.