Showing papers on "Reflection (physics) published in 2022"
TL;DR: In this article, the authors examined the complex two-dimensional flow field resulting from the interaction of a plane shock wave entering a symmetrical cavity with a curved end wall, and provided new simulation and experimental evidence of the ignition behavior in various reflectors, supporting the effect of enhancing shock wave focusing on the ignition performance.
49 citations
TL;DR: In this paper, an asymmetric viscoelastic metamaterial constructed from a unit with two distinct resonators selected to isolate elastic waves in a large coupled locally resonant bandgap (LRBG) and simultaneously realize designed unidirectional zero reflection (UZR).
12 citations
TL;DR: In this article, the effect of concentration gradient on detonation re-initiation behavior in a bifurcated tube full of oxyhydrogen mixture was numerically studied by employing an OpenFOAM based solver DCRFoam.
12 citations
TL;DR: In this article, the authors derived the leak-induced reflection coefficient at the measurement point by incorporating the additional damping effect of the reflection wave propagation process along the pipeline, which was then fully validated by MOC-based numerical and experimental laboratory applications.
12 citations
TL;DR: Wang et al. as mentioned in this paper proposed a modified minimum variance method, where waveform information was integrated into algorithm imaging procedure to improve the performance of the LW imaging with a sparse transducer array.
Abstract: Lamb wave minimum variance imaging is a promising method for visual damage identification and localization with a sparse transducer array. Imaging performance of minimum variance is highly dependent on the design accuracy of look-direction to describe amplitude relationship of array reflection signals. Look-direction is the combination of a directivity reflection pattern and an attenuation with propagation distance. However, reflection pattern is closely related to damage parameters (e.g. type, orientation and size) and these parameters are usually unknown beforehand. Therefore, accurate design of look-direction is difficult or even impossible, and design error can significantly degrade imaging performance. To overcome this limitation, a modified minimum variance method is proposed in this study. Besides amplitude information, waveform information is integrated into algorithm imaging procedure. Correlation coefficient between local signal and excitation waveform is calculated to generate the distribution of weights for diagonal loading. Diagonal loading weight is an adjustable coefficient in minimum variance algorithm to control the tolerance for look-direction error. With larger weights for potential damage locations, tolerance for inaccuracy in look-direction is increased, and imaging performance is accordingly improved. Experiments on both aluminum plates and composite laminates are carried out to demonstrate the performance improvement of modified method.
12 citations
TL;DR: In this article, a new form of Aki-Richards approximate reflection equation is derived on the assumption that the inverse of coefficient matrix exists, which avoids inverse of large matrix and improves the precision of density estimation.
10 citations
TL;DR: In this paper, the authors proposed a simulation method for displaying the entire process of multi-field coupling ultrasonic excitation, propagation, and reception based on CT scanning reconstruction of the coal pore-fracture structure model.
7 citations
TL;DR: In this article, the authors show that tilted optical feedback with a misaligned reflection mirror triggers quantum cascade lasers to generate low-frequency oscillations, including irregular pulse oscillations and square wave oscillations.
Abstract: Quantum cascade lasers are highly stable against optical feedback, where the reflection mirror is well aligned with the optical path. Therefore, it is challenging to produce pulse oscillations in quantum cascade lasers through normal optical feedback. In this work, we show that tilted optical feedback with a misaligned reflection mirror triggers quantum cascade lasers to generate low-frequency oscillations, including irregular pulse oscillations and square wave oscillations. The oscillation period is in the microsecond range, and generally decreases with increasing tilt angle. In addition, the duty cycle of the square waves is tunable through varying the tilt angle. It is also found that a weak feedback strength or a low pump current yields rare occurrence of the pulse oscillations.
3 citations
TL;DR: In this article, the authors proposed an analytical approach for optimizing the case-dependent parameters of the implicit relaxation zones in finite-volume-based flow simulations with free-surface waves.
3 citations
TL;DR: In this paper, the authors investigate how launching an acoustic shear wave, they can control the domain wall motion, and they show that at sufficiently large amplitudes of the shear displacement, the speed of the forced DW motion can reach a sizeable fraction of sound speed.
3 citations
TL;DR: In this paper, a three-dimensional time-dependent radiative transfer code, TRINITY (Time-dependent Radiative transfer In Near-Infrared TomographY), for in-vivo diffuse optical tomography (DOT) was developed based on the design of long radiation rays connecting boundaries of a computational domain.
Abstract: We develop a new three-dimensional time-dependent radiative transfer code, TRINITY (Time-dependent Radiative transfer In Near-Infrared TomographY), for in-vivo diffuse optical tomography (DOT). The simulation code is based on the design of long radiation rays connecting boundaries of a computational domain, which allows us to calculate light propagation with little numerical diffusion. We parallelize the code with Message Passing Interface (MPI) using the domain decomposition technique and confirm the high parallelization efficiency, so that simulations with a spatial resolution of ∼ 1 millimeter can be performed in practical time. As a first application, we study the light propagation for a pulse collimated within θ ∼ 15 ∘ in a phantom, which is a uniform medium made of polyurethane mimicking biological tissue. We show that the pulse spreads in all forward directions over ∼ a few millimeters due to the multiple scattering process of photons. Our simulations successfully reproduce the time-resolved signals measured with eight detectors for the phantom. We also introduce the effects of reflection and refraction at the boundary of medium with a different refractive index and demonstrate the faster propagation of photons in an air hole that is an analogue for the respiratory tract.
TL;DR: In this paper, the hydrodynamic performance of composite wavy submerged porous plate attached to a wall is investigated using numerical method multi-domain boundary element method in the linearized water wave theory in which wave past the porous barriers are modeled using Darcy's law.
Abstract:
The hydrodynamic performance of composite wavy submerged porous plate attached to a wall is investigated using numerical method multi-domain boundary element method in the linearized water wave theory in which wave past the porous barriers are modeled using Darcy’s law. Effect of the presence of wall on the hydrodynamic parameters like reflection coefficient, dimensionless wave height, wave force and moment acting on the composite wavy porous structure, and horizontal force on the vertical rigid wall is analyzed for various physical parameters like the number of ripple wavelength, structural porosity, submergence depth, and relative amplitude of composite wavy porous plate. The study demonstrates that the efficiency of hydrodynamic characteristics of the composite wavy porous plate attached to the wall is better compared to a horizontal porous plate attached to the wall of the same applicability conditions (around 27% reduction in wave reflection). Moreover, optimum performance of this kind of breakwater system is increased by considering the lower submergence, higher relative ripple amplitude, appropriate relative amplitude, and suitable moderate porosity of the structure in the range of wavenumber 1 < k0h < 5. Dimensionless wave height, horizontal load on the impermeable wall are reduced to zero, while substantial minimization of vertical load on the structure with suitable consideration of the other influencing parameters of porosity Gp = 0.3, relative amplitude Ds/h = 0.1, relative ripple wavelength m > 3, and submergence depth h1/h = 0.3. The present structural arrangement will be useful for attenuating wave effects on the sea wall.
TL;DR: In this article, five surfaces at different average roughness (Sa) were created on a massive slice of malachite with the final aim to investigate possible variations of spectral features collected through noncontact infrared reflection spectroscopy.
TL;DR: In this article, the reflection and transmission of waves at an interface of piezoelectric (ALN and PZT-5T) half-spaces with microstructures were investigated.
TL;DR: Concave front pile-supported breakwaters, namely, Galveston wall-shaped pilesupported breakwater (GS-PSB) and circular cum parabola-shaped PSB, have proven their feasibility as mentioned in this paper.
Abstract: Concave front pile-supported breakwaters, namely, Galveston wall-shaped pile-supported breakwater (GS-PSB) and circular cum parabola-shaped pile-supported breakwater (CPS-PSB), have proven...
01 Jan 2022
TL;DR: In this article, a variational formulation is employed to find approximations to the solution in all realizations, as well as for the mean energy fluxes, which conform to conservation of energy.
TL;DR: The ability to create subsurface images whose amplitudes are proportional to the elastic wavefield variations recorded within seismic data as a function of reflection angle is fundamental for underwater imaging as mentioned in this paper.
Abstract: The ability to create subsurface images whose amplitudes are proportional to the elastic wavefield variations recorded within seismic data as a function of reflection angle is fundamental f...
DOI•
01 Jan 2022
TL;DR: In this article, the dependence of the upwind and crosswind components of the sea surface slope, as well as the anisotropy of the slope on the range of waves creating them is analyzed.
Abstract: The dependence of the variance of the upwind and crosswind components of the sea surface slope, as well as the anisotropy of the slope on the range of waves creating them is analyzed. We used radio and optical sounding data, as well as in situ measurements (measurements by laser inclinometers, string sensors, and wave buoys). Dependences of the integral characteristics of the slopes created by waves whose lengths are in the range with a changing boundary: from the longest waves to waves of a given length are constructed. It is shown that the estimation of the anisotropy coefficient obtained in the framework of the well-known Cox-Munk model, which is widely used in applications related to the reflection of electromagnetic waves, does not agree with the estimates of this coefficient calculated from in situ measurements.
TL;DR: In this paper, the reflection and transmission of a wave falling onto a stratified medium is analyzed in terms of the RT-matrixes establishing a relation between the wave amplitudes in the asymptotic regions z → ± ∞.