Effect Of Incidence Angle Research Articles

Coupled effect of light incidence angle and deformation on the light-induced bending of liquid crystal elastomers plates

In this paper, the light-induced bending of a liquid crystal elastomers (LCEs) plate with the coupled effect of light incidence angle and deformation is studied for the first time. Based on the Reissner-Mindlin plate theory, a finite element model incorporating the coupled effect is developed to investigate the bending behavior of the LCEs plate. Deflections of the LCEs plate subjected to the light illumination with different light incidence angles are given. It is found that the coupled effect will significantly affect the bending deformation of the LCEs plate such as the location of the peak and the bending shape. Comparisons of the spontaneous bending of the LCEs plate with and without the coupled effect demonstrate the necessity of this study, especially for the LCEs plate subjected to the non-normal incidence light.

Graphene-embedded planar and cylindrical Oldenburger–Kolakoski aperiodic photonic crystals

In this paper, we examine the transmission and absorption spectra of light waves in both planar and cylindrical quasiperiodic structures known as Photonic Crystals. In these quasiperiodic multilayers, graphene sheets are inserted between planar and concentric layers of two different dielectric materials (namely TiO2 and SiO2). These structures are called Planar Photonic Crystals (PPCs) and Cylindrical Photonic Crystals (CPCs), respectively. The spatial arrangement of the dielectric layers follows the aperiodic Oldenburger–Kolakoski (O–K) sequence. The transfer matrix method is used to calculate the transmission and absorption spectra of obliquely incident TE and TM waves to investigate the effects of graphene, aperiodic disorder, and incidence angle on the physical behavior of the system. The numerical results reveal that the transmission spectra for cylindrical geometry differ significantly from those for planar geometry, even in the case of a normal incidence angle. Furthermore, the transmission of TM modes is higher than that of TE modes for incidence angles greater than 30°. Finally, we have demonstrated that a substantial number of peaks in the absorption spectra for the CPC case are higher than those for the PPC case, which is a result that may be useful for enhancing the efficiency of optical sensors.

Determination of temperature profile inside a PV module operating under specific conditions using a model coupling internal heating to optical absorption

In this study, the complex dynamics behind heat transfer within photovoltaic (PV) solar modules under spectral solar illumination are investigated. A new model coupling internal heating to optical absorption is derived from equations governing light-matter interaction throughout PV module multilayered structure. Reflection and transmission at each interface between two neighboring layers inside a PV module as well as absorption in each layer are taken into account. Dielectric properties of each interface are used to calculate its wavelength dependent reflectance and transmittance according TE and TM light polarization modes. Optical properties of each layer are utilized to determine its absorption coefficient and internal source of warming. Effects of incidence angle and light polarization modes on internal heat function are also analyzed. Heat equation is then solved in steady state limiting case and Temperature profiles inside a PV module under STC and NOCT conditions are determined.

Exploring mechanochemistry of pharmaceutical cocrystals: effect of incident angle on molecular mixing during simulated indentations of two organic solids.

The solid-state reaction of the active pharmaceutical ingredient theophylline with citric acid is a well-established example of a mechanochemical reaction, leading to a model pharmaceutical cocrystal. Here, classical force field molecular dynamics was employed to investigate the molecular mixing and structural distortion that take place on the mechanically driven indentation of a citric acid nanoparticle on a slab of crystalline theophylline. Through non-equilibrium molecular dynamics simulations, a 6 nm diameter nanoparticle of citric acid was introduced onto an open (001) surface of a theophylline crystal, varying both the angle of incidence of the nanoparticle between 15° and 90° and the indentation speed between 1 m s-1 and 16 m s-1. This theoretical study enabled the evaluation of how these two parameters promote molecular mixing and overall structural deformation upon the mechanical contraction of theophylline and citric acid, both of which are important parameters underlying mechanochemical cocrystallisation. The results show that the angle of incidence plays a key role in the molecular transfer ability between the two species and in the structural disruption of the initially spherical nanoparticles. Changing the indentation speed, however, did not lead to a discernible trend in molecular mixing, highlighting the importance of the incident angle in mechanochemical events in the context of supramolecular chemistry, such as the disruption of the crystal structure and molecular transfer between molecular crystals.

Mitigating Incidence Angle Effects in Airborne SAR Time-Series Crop Classification: Integrating Transfer Learning and Variational Mode Decomposition

Mitigating Incidence Angle Effects in Airborne SAR Time-Series Crop Classification: Integrating Transfer Learning and Variational Mode Decomposition

Effects of Higher Sloshing Modes on the Response of Rectangular Concrete Water Storage Tanks with Different Aspect Ratios to Near-Field Earthquakes

Near-field earthquakes have been shown to have different effects on structures than far-field events. This study examines the dynamic response of a rectangular concrete liquid storage tank with tapered walls to near-field ground motions, with particular emphasis on the effect of higher sloshing modes. The tank’s numerical modeling, calibrated using experimental results, was performed considering the tank’s wall flexibility. Seven selected near-field records were applied in each case, and the effects of the first five sloshing modes on the tank response at three different locations, including the corner, middle of the long wall, and middle of the short wall, were investigated. The effect of the earthquake incident angle on the tank’s response was also studied by applying major and minor horizontal earthquake components once along the longer and shorter tank walls, respectively, and vice versa. Results show that the tank corner may have a sloshing height up to 50% greater than the middle of the walls and that the maximum sloshing response is substantially influenced by the spectral acceleration value at the first sloshing period. Higher sloshing modes are found to affect the sloshing response, with a maximum R2 score of 0.95, depending on the excitation’s incidence angle.

Effect of variable laser incident angles on microstructure and mechanical properties of laser-cladded Inconel 718

In the laser cladding process of complex components, laser deflection is a significant issue that greatly affects manufacturing quality. This study investigates the influence of different incident angles on the microstructure and wear resistance of laser-clad layers. Firstly, an Inconel 718 coating was prepared on an Inconel 718 substrate using an IPG fiber laser. Next, the macrostructure and microstructure of the coating were observed using electron microscopy. Finally, the microhardness of the coating was measured, and the underlying mechanisms affecting wear resistance due to incident angle were revealed. The results show that with an increase in the laser incident angle, the laser energy distribution becomes more divergent, leading to a shift in the peak energy density and changes in the macroscopic morphology of the melt pool, exhibiting a non-Gaussian distribution and resulting in increased cellular dendrite count and coarsened grains. Laser deflection causes variations in microstructure and properties between inner and external angles, where higher laser energy density and temperature gradients at the inner angle result in finer grains and more numerous smaller secondary dendrites on the dendritic arms, along with less severe element segregation and higher microhardness at the inner angle.

Quasi-BIC based all-dielectric metasurfaces for ultra-sensitive refractive index and temperature sensing

In this paper, an all-dielectric metasurface that measures refractive index and temperature using silicon disks is presented. It can simultaneously produce three resonances excited by a magnetic toroidal dipole, magnetic toroidal quadrupole, and electric toroidal dipole, in the THz region. Asymmetric structures are used to generate two quasi-bound states in the continuum (BIC) resonances with ultra-high-quality factors driven by magnetic and electric toroidal dipoles. We numerically study and show the dominant electromagnetic excitations in the three resonances through near-field analysis and cartesian multipole decomposition. The effects of geometric parameters, scaling properties, polarization angles, incident angles, and silicon losses are also investigated. The proposed metasurface is an excellent candidate for sensing due to the extremely high-quality factor of the quasi-BICs. The results demonstrate that the sensitivities for liquid and gas detection are Sl = 569.1 GHz/RIU and Sg = 529 GHz/RIU for magnetic toroidal dipole, and Sl = 532 GHz/RIU and Sg = 498.3 GHz/RIU for electric toroidal dipole, respectively. Furthermore, the sensitivity for temperature monitoring can reach up to 20.24 nm/°C. This work presents a valuable reference for developing applications in the THz region such as optical modulators, multi-channel biochemical sensing, and optical switches.

Influence of Temperature and Incidence Angle on the Irradiation Cascade Effect of 6H-SiC: Molecular Dynamics Simulations.

SiC devices have been typically subjected to extreme environments and complex stresses during operation, such as intense radiation and large diurnal amplitude differences on the lunar surface. Radiation displacement damage may lead to degradation or failure of the performance of semiconductor devices. In this paper, the effects of temperature and incidence angle on the irradiation cascade effect of 6H-SiC were investigated separately using the principles of molecular dynamics. Temperatures were set to 100 K, 150 K, 200 K, 250 K, 300 K, 350 K, 400 K and 450 K. The incidence direction was parallel to the specified crystal plane, with angles of 8°, 15°, 30°, 45°, 60° and 75° to the negative direction of the Z-axis. In this paper, the six types of defects were counted, and the microscopic distribution images and trajectories of each type of defect were extracted. The results show a linear relationship between the peak of the Frenkel pair and temperature. The recombination rate of Frenkel pairs depends on the local temperature and degree of aggregation at the center of the cascade collision. Increasing the angle of incidence first inhibits and then promotes the production of total defects and Frenkel pairs. The lowest number of total defects, Frenkel pairs and antisite defects are produced at a 45° incident angle. At an incidence angle of 75°, larger size hollow clusters and anti-clusters are more likely to appear in the 6H-SiC.

Analytical Approach to Two‐Dimensional Full Reflections of Fast Magnetosonic Waves Due To Mesoscale Density Boundaries

AbstractPropagation of fast magnetosonic (MS) waves in the equatorial plane has attracted a growing attention in recent studies. Although computer simulations including ray tracing, PIC, and full wave simulations have been utilized to study the propagation of MS waves, analytical approach is needed to investigate the physics insight. In this letter, we first derive the wave equations describing the two‐dimensional propagation of MS waves under the assumption that the mesoscale density inhomogeneity is only along one dimensional. After investigating the essential role of the potential function in the wave equation for the full reflection of MS waves, we find that full reflection can occur when the minimum potential is significantly negative. Finally, we have discussed the effects of incidence angles and wave frequencies on the full reflection. Our results show that MS waves with an incidence angle or wave frequency greater than the critical value would be fully reflected.

Multiband terahertz metamaterial perfect absorber for microorganisms detection

We report a multi-resonant terahertz (THz) metamaterial perfect absorber (MPA)-based biosensor in the working frequency range of 0 - 3.8 THz for sensing of microorganisms (such as fungi, yeast) and wheat pesticides. Nearly 100% absorption is realized at f_1= 1.7THz, f_2= 2.8THz, f_3=3.2THz, and f_4=3.5THz. We designed our THz MPA sensor making resonators’ gap area compatible with the microorganisms’ size. To obtain optimum performance of the MPA, a mapping of amplitudes and shifts in the absorption resonance peaks with different structural parameters of the resonators is carried out. A very high-frequency shift is obtained for microorganisms such as Penicillium chrysogenum (fungi), yeast, and pesticides (Imidacloprid, N, N-Diethyldithiocarbamate sodium salt trihydrate, Daminozide, N, N-Diethyldithiocarbamate sodium salt hydrate, and Dicofol). An equivalent circuit model using Advance Design System (ADS) software is developed. The calculated results through the model show similar trends as obtained in the simulations using CST. Investigations of the effect of incidence angle of THz wave on the absorption spectra of the MPA are also carried out. It is found that incidence angle does not impact the stability of the lower resonance absorption peak (1.79THz). Due to the wide working frequency range, the proposed sensor is extremely suitable for the detection of all range of pesticides because their specific absorption fingerprint lies in the frequency range of 0–3.8THz. We believe that our sensor could be a potential detection tool for detecting pesticide residues in agriculture and food products. The THz MPA-based biosensor is capable of detecting a very small change in the effective dielectric constant of the MPA environment. Therefore, it can also offer huge opportunities in label-free biosensing for future biomedical applications.

Role of initial density profiles in simulations of coronal wave-coronal hole interactions

Interactions between global coronal waves (CWs) and coronal holes (CHs) reveal many interesting features of reflected waves and coronal hole boundaries (CHB). However, such interactions have scarcely been studied thus far. Magnetohydrodynamic (MHD) simulations can help us to better understand what is happening during these interaction events and thus to achieve a broader understanding of the parameters involved. In this study, we performed the first 2D MHD simulations of a CW–CH interaction that include a realistic initial wave density profile consisting of an enhanced wave component as well as a depleted one. We varied several initial parameters, such as the initial density amplitudes of the incoming wave, the CH density, and the CHB width, which are all based on actual measurements. We analysed the effects of different incident angles on the interaction features and we used the corresponding time-distance plots to detect specific features of the incoming and the reflected waves. We found that the specific combination of a small CH density, a realistic initial density profile, and a sufficiently small incident angle can lead to remarkable interaction features, such as a large density amplitude for the reflected wave and greater phase speed for the reflected wave with respect to the incoming one. The parameter studies in this paper provide a tool for comparing time-distance plots based on observational measurements to those created from simulations. This has enabled us to derive interaction parameters from observed CW–CH interaction events that usually cannot be obtained directly. The simulation results in this study are augmented by analytical expressions for the reflection coefficient of the CW–CH interaction, which allows us to verify the simulations results in an complementary way. This work, with its focus on parameter studies that examine the initial density profile of CWs, is the first of a series of studies aiming to ultimately reconstruct actual observed CW–CH interaction events by means of MHD simulations. These results improve our understanding of the involved interaction parameters in a comprehensive way.

Effect of laser oscillation and beam incident angle on porosity in double-sided filler welding of 2219 aluminum alloy T joint

In the current research, the double-sided laser beam oscillation filler welding (DLBOW) with beam incident angle from 20° to 40° were carried out for 2219 Al-Cu alloy T joint welding. Double-sided laser beam filler welding (DLBW) was conducted as a reference group. 3D computed tomography (CT) scanning analysis method was performed to investigate the precise three-dimensional locations of the porosity defects in the T joints. High-speed photography was conducted to evaluate the keyhole stability. The dynamic behavior of keyhole of DLBW and DLBOW was simulated by Flow-3D to study the formation process of pores. The effects of beam oscillation and beam incident angle on the macrostructure, microstructure, porosity, and mechanical property of T joints were discussed. It was found that beam oscillation and smaller beam incident angle promoted porosity suppression. The mechanical properties of T joints were improved by laser oscillation. With the beam incident angle of 20°, the porosity of T joint welded by DLBOW was lowest (0.26 %). The hoop tensile strength and T-pull tensile strength of the T joint were 403 MPa and 302 MPa, approximately 89.5 % and 71.6 %, in contrast with that of the base metal.

Investigation of NS-single-point laser ablation of bronze under different incidence angles and pulses

A fundamental understanding of ablation in different incidence angles is indispensable to expand the result to volume ablation where nonperpendicular irradiation exists. So far, no study with this orientation has been conducted in the category of volume laser machining. In this study, a nanosecond laser with different fluencies was utilized for single-point ablation experiments. The effect of incidence angles of 0°, 30°, and 60° on the ablation depth and the crater geometry was evaluated. Different laser pulse numbers are also considered. The results show that the ablation depth for 0° and 30° angles is almost in the same range for the initial pulses, but afterward, the ablation depth for the incidence 30° drops considerably. As the number of incident pulses increases, the ablation depth first develops approximately linearly and then grows exponentially. By changing the incident from 0° to 60°, the affecting area changes as well. The affecting area could be categorized into two distinct areas: (1) ablation area (A.A) where the crater ablation depth rapidly increases for the first 20 pulses and then, as more incident pulses arrive, it does not grow anymore and reaches a plateau due to the increase in the ablation depth. The second area (2) is the heat-affected area (H.A.A) of the crater where no further ablation occurs, but due to heat accumulation, it becomes constantly bigger when more incident pulses strike the crater. This heat-affected area tends to stay almost constant for the first incident pulses (up to 10) and, after a sharp increase, tends to enlarge steadily as the number of incident pulses rises to 70.

Investigation on the effectiveness of transpiration cooling under the influence of shock wave

As an advanced active cooling method, transpiration cooling can be used for thermal protection of high-temperature wall. The change of cooling effect caused by the incident shock wave on the transpiration cooling boundary layer is sufficient to affect the safe flight of the aircraft. In this paper, the interaction mechanism between shock wave and transpiration cooling is studied based on the thermal equilibrium model. The effects of shock wave incident angle, coolant injection ratio, Mach number of high enthalpy airflow and coolant type on thermal protection effect were studied respectively. Shock wave incidence in the boundary layer of transpiration cooling can cause the change of coolant flow and heat sink distribution in porous media, and cause the fluctuation of fluid parameters in the boundary layer. The temperature inhomogeneity on the porous wall and the inhomogeneity of the total enthalpy difference are markedly affected by the shock wave intensity. The heat insulation effect of the coolant on the solid surface limits the improvement effect of the increase of the injection ratio on the effective heat absorption power. Hydrogen as a coolant can form a better cooling effect and has less resistance to the mainstream.

A semi-implicit finite volume scheme for blood flow in elastic and viscoelastic vessels

A novel staggered semi-implicit finite volume method for the simulation of one-dimensional blood flow in networks of elastic and viscoelastic vessels is proposed. The one-dimensional blood flow model is split into three subsystems: one containing the nonlinear convective terms, a second one for the viscoelastic terms and a final subsystem for the pressure-related terms. An explicit approach is then employed to discretize the convective subsystem, while the viscous and pressure terms are treated implicitly. This leads to a CFL-type time step restriction which depends only on the bulk velocity of the flow and not on the speed of the pressure waves or on the visco elasticity. As such, the method is computationally efficient in case of low speed index, which is equivalent to a low Mach regime for the Navier-Stokes equations. To extend the proposed methodology to the case of networks, a novel and very simple 3D approach for the treatment of junctions is proposed. Each junction is represented by a unique three-dimensional primal cell and the Euler equations are employed to approximate the velocity and pressure unknowns. A multidimensional numerical flux then takes into account the elementary information of the junction geometry, namely normal vectors and areas of the incident vessels, when approximating the blood flow at the cell interfaces embedded in the 3D cell. As such, the final scheme, based on guaranteeing mass and momentum conservation through the junction, is able to capture reflecting waves properly considering the effect of the different incident angles of vessels at a junction. The proposed methodology is carefully validated in the context of single elastic and viscoelastic vessels and small networks showing a good agreement with available analytical, experimental and numerical data.

Three-dimensional shape optimization of a submerged body under wave diffraction

This study explores the use of shape optimization to reduce wave forces on a submerged floating body subjected to wave diffraction. To this end, gradient-based shape optimization is adopted, in which dimensionless wave excitation forces are the optimization objective. A shape parameterization method based on the Fourier-series expansion is developed that permits the representation of an arbitrary three-dimensional floating body. The discrete adjoint method is utilized to calculate the gradient of the objective function with respect to the shape parameters. Using three-dimensional shape optimization, taking the initial shape to be a hemisphere, a significant reduction in surge, heave, and pitch wave forces is achieved, with a maximum reduction of 48.40%, 68.43%, and 46.22%, respectively. Furthermore, optimization effectively suppresses wave run-up, with a maximum reduction of 15.62%. A comprehensive analysis of parameters is performed to reveal the effects of wave number, incident angle, and shape parameters on the final optimized shape and wave load characteristics. This study provides a solid guide to the optimization of floating offshore platforms and the development of innovative structural systems.

Effect of laser incidence angle on the femtosecond laser ablation characteristics of silicon carbide ceramics

Due to their excellent physical and chemical properties, silicon carbide ceramics have become representative high-performance materials in aerospace, energy power, biomedical, and other fields. However, as a typical hard and brittle material, silicon carbide ceramics possess incredibly high hardness and brittleness, which pose challenges to traditional mechanical processing methods. Laser processing, as a non-contact method, offers a wide processing range and high processing efficiency and has broad application prospects in the field of hard and brittle material processing. In this paper, laser ablations of silicon carbide ceramics with various combinations of process parameters were carried out by using a five-axis infrared femtosecond laser processing system. The changes in the ablation morphology with different incidence angles and laser power were discussed. The results demonstrate that the ablation threshold of silicon carbide ceramics initially increases, then decreases, and finally increases with the increase of laser incident angle. This trend may be attributed to the effect of the incidence angle on the laser absorption rate of silicon carbide ceramics. The ablation morphology of silicon carbide ceramics can be divided into three zones based on color and oxygen distribution: the ablation removal zone, ablation edge zone, and ablation affected zone. At the same laser incidence angle, the ablation range and depth gradually increase with the increase in laser power, but the growth rate gradually decreases. Furthermore, at the same laser power, as the incident angle increases, the laser energy density gradually decreases, and the long axis of the actual ablation area gradually lengthens while the short axis gradually shortens. This work could provides technical and theoretical support for laser surface processing at multiple incidence angles, which is conducive to multi-axis processing of complex curved parts.

Research on evolution process of full-layer incision of skin tissue under different laser incidences.

Considering difficulties of achieving vertical incidence of beam in different positions of skin, it is significant to study potential effects of incidence angles of laser on incisions. Surgical platform with a 1064 nm continuous fiber laser was established. Incident angle was adopted and real-time temperature fluctuations in laser operating area could be monitored. The rats were treated with laser at day 0 and day 3 after incision modeling, and H&E, Masson, Sirius Red, and Immuno-histochemical staining and enzyme-linked immunosorbent assay were adopted at day 3, 7, 14 to analyze the performance of healing. Laser with energy density of 67.54 J/mm2 can effectively accelerate wound healing in vivo, in which a laser with incident angle around 60° can effectively avoid scar hyperplasia. Therefore, the use of low energy laser with a small deflection angle has a good clinical application prospect in promoting wound healing.

Study on transmission and reflection characteristics of plane S1 wave at the interface between saturated frozen soil and elastic solid bedrock

Based on the propagation theory of elastic waves in frozen poroelastic media and elastic media, a theoretical model of saturated frozen soil and elastic solid bedrock is established. The saturated frozen soil is lying on an elastic solid bedrock and is modeled as a porous material containing a three-phase medium that contains two solids (soil skeleton and ice particles) and a compressible viscous fluid. Based on the Helmholtz vector decomposition and the boundary conditions on the interface, the theoretical expressions of the amplitude ratio and displacement of the plane S1 wave incident from the saturated frozen soil to the elastic solid bedrock interface are obtained. The effects of incidence angle, frequency, cementation parameters, saturation, and contact parameters on amplitude ratio and displacement were investigated. The results indicate that only S wave and horizontal displacement exist when the incident angle [Formula: see text] = 0°. As cementation parameters, saturation, porosity, and contact parameters increase, the critical angle appears earlier. Each wave has different degrees of pulses when reaching the critical angle, among which the transmitted P wave and the reflected S2 wave are the most significant. At higher saturation, it is observed that the amplitude ratio of the reflected S2 wave decreases significantly. The horizontal and vertical displacements increase significantly with increasing frequency.