Reflection Phenomena Research Articles

Design of output filter device of mine-used high-voltage inverter for long-distance power supply

During the long-distance transmission of the Pulse width modulation ( PWM ) signal of the mine-used inverter, the voltage reflection phenomenon leads to a higher peak voltage at the motor end, which accelerates the insulation aging of the motor and reduces the overall reliability of the system. In this paper, ANSYS is used to simulate the electromagnetic field of cable and cable connector and extract the distributed parameters. On this basis, the simulation model of long-distance power supply system of 3300V mine-used high-voltage inverter is established by MATLAB / Simulink, and the harm caused by peak voltage to motor is analyzed. According to the cable length, the number of cable connectors and the power loss of the device, a design scheme of LRC filter device meeting the power supply distance of 3000m is proposed. Simulation and experimental results verify the effectiveness of the filter device.

Особенности фиксации архитектурного наследия в белорусском изобразительном искусстве (на примере выставки «Мой Минск – мое вдохновение»)

The exhibition titled «My Minsk – My Inspiration» was organized at the Museum of the History of Minsk and the Belarusian Union of Artists and held in 2021 from September 9 to 26 at the Mikhail Savitsky Art Gallery. This exhibition brought together fine arts and cinema: along with pictorial and graphic works, a number of documentaries in Minsk were presented for viewing, as well as feature films shot especially in Minsk. The purpose of the article is to evaluate paintings and graphic works from the collection of the Belarusian Union of artists presented at the exhibition «My Minsk – my inspiration» in the art gallery of Mikhail Savitsky in Minsk. Created between 1945 and 2018, the mentioned works reflect buildings and streets, valuable in terms of urban development. Paintings have historical and artistic value. The article provides the author's definition of the term «artistic reflection». Based on the method of typing the essence of three artistic reflections of the architectural heritage is revealed: «mirror reflection of artistic heritage», «reflection with the phenomena of artistic reflection» and «fiction in the reflection of the architectural heritage», as well as the identification of works to identify signs of artistic reflection.

Parasitic reflection separation deflectometry based on harmonic analysis

In the measurement of transparent planar element using deflectometry, the fringe patterns reflected off the double surfaces of transparent planar element are superimposed on the camera, causing the phenomenon of parasitic reflection. The parasitic reflection makes it difficult for traditional deflectometry to accurately obtain the front surface shape. Previous solutions suffer from inability to reliably measure the element with thickness less than 10 mm. In practice, modulated by the nonlinear response, the signal captured by the camera contains higher-order harmonics, whose frequency difference is larger than that of the fundamental. Therefore, a novel method based on harmonic analysis is proposed. This parasitic issue of thin transparent element can be eliminated by analyzing the harmonic component in power spectrum. The surface shape of element with thickness of 5 mm is measured in experiment. The measurement error is around 80 nm in RMS with a diameter of 52 mm.

Specular Reflection Suppression through the Adjustment of Linear Polarization for Tumor Diagnosis Using Fluorescein Sodium.

In tumor surgery, the edges of the tumor can be visually observed using a fluorescent contrast agent and a fluorescent imaging device. By distinguishing it from normal tissues and blood vessels, it is possible to objectively judge the extent of resection while visually observing it during surgery, and it guarantees safe tumor resection based on more information. However, the main problem of such an imaging device is the specular reflection phenomenon. If specular reflection overlaps with important lesion locations, they are a major factor leading to diagnostic errors. Here, we propose a method to reduce specular reflection that occurs during tumor diagnosis using a linear polarization filter and fluorescent contrast agent. To confirm the effect of removing specular reflection, a self-made fluorescein sodium vial phantom was used, and the reliability of the results was increased using a large animal (pig) test. As a result of the experiment, it was possible to obtain an image in which specular reflection was removed by controlling the rotation angle of the filter by 90° and 270°, and the same results were confirmed in the phantom experiment and the animal experiment.

Unique interface reflection phenomena tailored by nanoscale electromagnetic boundary conditions.

Local interface response effects are neglected based on the traditional electromagnetic boundary conditions (EMBCs) in an abrupt interface model. In this study, generalized nanoscale EMBCs are derived with interface response functions (IRFs) representing field inhomogeneity across the interface based on integral Maxwell's equations. They are rewritten in two different forms that correspond to the equivalent abrupt interface models with interface-induced dipoles or charges and currents. Interesting behaviors of Brewster angle shifting, non-extinction at Brewster angle, and unique absorption or gain effects are revealed based on the advanced Fresnel formula. IRFs-controlled GH-shift and angular GH-shift of a Gaussian beam near the Brewster angles are generated by the gradient interface. These unique phenomena provide some guidance for measuring the IRFs and expanding interface photonics at the nanoscale.

Reduction of Specular Reflection Based on Linear Polarization Control for Fluorescence-Induced Diagnostic Evaluation.

The primary goal of cancer surgery is to completely eliminate tumors. A real-time diagnostic method uses a fluorescence contrast agent and a surgical microscope to assess the status of tumor resection and the patient’s blood circulation. The biggest problem in imaging diagnostics using a microscope is the specular reflection phenomenon. While observing a lesion, the observation field may be obstructed due to specular reflection, making it difficult to obtain accurate results during the diagnostic process. Herein we propose a method to reduce specular reflection during tumor diagnosis by introducing a linearly polarized filter for a surgical microscope system. The method of angular direction adjustment of the filter ensures that only the horizontally polarized light passes through it, thereby obstructing the specular reflection. As a result of removing specular reflection, clear images were obtained at 90° and 270°. This experiment was conducted using phantoms and animals. Our results prove that the proposed method can be applied to imaging cameras used in internal medicine, surgery, and radiology for diagnosis.

Self-assembly of hierarchical MXene@SnO2 nanostructure for enhancing the flame retardancy, solar de-icing, and mechanical property of polyurethane resin

Taking into consideration the frigid and thunderstorms, the flame retardancy and de-icing performance are simultaneously desiderated for some open-air key equipment, such as air fuselage and wind turbine blades. Here, inspired by the anti-reflection phenomenon of moth eyes and cicada wings, a multi-functionalized and biomimetic MXene@SnO2 hierarchical nanostructure is prepared to effectively impart flame retardancy and solar de-icing performance to thermoplastic polyurethane (TPU) resin used widely as the finishing coat of protective materials of open-air equipment. Based on the catalytic effect and barrier function, the addition of hierarchical MXene@SnO2 nanostructures also effectively decreases the release of heat and toxic smoke from PU resin, as confirmed by reductions of 50.5% and 33.1% in the peak heat release rate and smoke production rate, respectively. Due to the appropriate refractive index, the light reflection phenomenon is effectively suppressed, thus promoting solar absorption (∼90% at 0.4 mm film) and photo-thermal conversion (∼74.2 °C with simulated solar illumination of 1.0 kW/m2) in TPU-MXene@SnO2 nanocomposites. Within the environment of −20 °C, the surface temperature of TPU-MXene@SnO2 nanocomposites is still up to 32.7 °C and the surface ice pellet begins to melt at ∼40s, much earlier than 600s of pure TPU resin. In addition, the practical application of functionalized TPU nanocomposites is further improved by the higher mechanical properties, attributed to the strong interfacial interaction. Inspired by moth eyes and cicada wings, flame retardancy and solar de-icing performance are first integrated into polymer materials, thus effectively promoting their application in some extreme environments.

Reflection of temperature rate–dependent coupled thermoelastic waves on a non-local elastic half-space

Based upon the Green–Lindsay (GL) theory of thermoelasticity and the Eringen non-local elasticity theory, we describe the new constitutive relations and the field equations for generalized non-local thermoelastic model. The propagation of harmonically time-dependent thermoelastic plane waves of assigned frequency is studied in a homogeneous, isotropic, non-local infinite elastic solid by employing these equations. Reflection phenomenon of thermoelastic waves at a stress-free thermally insulated or isothermal flat boundary of a non-local thermoelastic solid half-space is also studied in case of incident coupled longitudinal wave. The amplitude ratios of the reflected waves to that of incident wave are determined analytically and numerically by considering an appropriate material. The numerical results are presented graphically to highlight the effects of various parameters of interest.

Attenuation and Reflection of TEM and TE Microwaves Through a Dielectric With Multipactor

A theoretical model in terms of RF and electric field is proposed for the attenuation and reflection of TEM and TE microwaves through a dielectric with multipactor. The reflected power is much lower than the attenuated power. Also, both ratios of reflected and attenuated powers increase dramatically when the RF decreases to be near the cutoff frequency for TE microwaves. The attenuation ratio can be larger than 10% and smaller than 0.1%, while previously, it is usually considered as a small constant. The phenomena of power attenuation and reflection are also observed directly by electromagnetic particle-in-cell simulations, and simulation results are consistent with theoretical results.

Simulation study to improve the sensitivity of surface plasmon resonance sensor by using ferric oxide, nickel and antimonene nanomaterials

In the present paper, a simulation work has been done to study about a hypersensitive Surface Plasmon Resonance (SPR) based sensor device created by the angular interrogation method based on Attenuated Total Reflection (ATR) phenomenon. The numerical analysis has been done by the method of transfer matrix and a plane polarised source of light of wavelength 633 nm approx (632.8 nm wavelength of He-Ne laser) has been used. In this device configuration, glass prism of Calcium fluoride (CaF2) has been used with Silver (Ag) metal using Kretschmann configuration, a diamagnetic material nanosheets of ferric oxide (Fe2O3), nickel (Ni) and a 2D material antimonene is used as a polymeric structure. All the important performing parameters of SPR sensor such as sensitivity, detection accuracy, quality factor has been calculated for different device configuration of SPR sensor. Fe2O3 and Ag layer thickness has been optimized by using genetic algorithms to obtain the highest sensitivity. The configuration gives the highest sensitivity 310°RIU−1 of projected SPR sensor when sensing medium RI varies from 1.330 to 1.335. For proposed design of SPR sensor the sensitivity and FWHM are high as compared to the conventional SPR senor having FWHM value 3.4995 (deg.). For the proposed device configuration bilayer of Ni and antimonene has been used as a polymeric substance to improve the sensitivity and protect device from corrosion. Penetration depth value of 110.5 nm and 3D plot of transverse electric (TM) field intensity has also been plotted. The numerical simulation is based on transfer matrix method and Fresnel equations and the used softwares are MATLAB and COMSOL multiphysics software. The proposed SPR sensor helps to detect the liquid analytes in the field of biomedical and environmental application.

Equiaxed Polycrystalline Ice for Ultrasonic Testing of Solids

Elastic waves traveling through polycrystalline ice Ih can experience distortion due to the transversely isotropic structure of its crystals. This can pose a challenge to nondestructive ultrasonic testing when ice is used as a coupling medium to transfer energy between an ultrasonic source and the solid to be inspected for the presence of damage. Here, it is shown that when ice is grown on a metallic solid using directional freezing techniques, it develops a coarse columnar grain structure, which causes the ultrasonic signals to vary greatly depending on which region of the ice volume is interrogated. On the other hand, if small ice particles are compacted around the solid and saturated with degassed liquid water before directional freezing, an equiaxed grain structure is obtained, which behaves as a homogeneous and isotropic medium. Furthermore, it is demonstrated that ultrasonic transmission through an ice-metal interface can be achieved regardless of the angle formed between the ultrasonic beam and the interface. Therefore, it is possible to overcome one of the fundamental limitations of conventional water coupling, which prevents transmission when the beam is not close to orthogonal to the interface due to the total reflection phenomenon. This property is useful to expand the scope of the application of ultrasonic testing to solids with complex geometries such as those obtained with additive manufacturing methods.

A low-loss passive filter for overvoltage mitigation of inverter-driven motors with ultra-long cables

Variable frequency drives (VFDs) are always considered in industrial applications because of their benefits. However, in applications with long cables, overvoltage spikes appear at the motor terminal due to the reflection phenomenon, causing the premature failure of the motor. Various passive and active techniques have been proposed to solve this issue. Among them, passive techniques are preferred due to their simplicity, low cost and effectiveness. However, the use of passive filters in ultralong cables is limited due to additional power dissipation. In this paper, L-RC filter is presented and shown to be efficient for ultra-long cables. The proposed filter does not have the limitations and problems associated with the conventional L and RC filters. The PWM inverter-fed ac motor drive system is fully modelled to evaluate the performance of the proposed filter. The presented model is simulated in the Matlab software and the effect of different parameters on the filter performance is evaluated. Finally, in an actual 37 kW system, the performance of the proposed filter is compared with that of the conventional filters. The experimental results show the good performance of the proposed filter in reducing the voltage overshoots, increasing the rise time and decreasing power dissipation.

Response of impedance parameters on waves in the micropolar thermoelastic medium under modified Green‐Lindsay theory

The present study is focused on devoting a model to estimate the response of impedance parameters in micropolar with modified Green-Lindsay (MMGL) generalized thermoelastic medium. The problem of reflection phenomena is formulated and explained for the considered model. Amplitude ratios of various waves are obtained for the MMGL model, Green-Lindsay (G-L,1972) thermoelastic model, and Lord-Shulman (L-S,1967) thermoelastic model for longitudinal displacement wave (LD-wave), thermal wave (T-wave), coupled transverse (CD-I) wave and coupled micro-rotational (CD-II) wave. These amplitude ratios are the functions of the angle of incidence, frequency, and impedance parameters. The impact of impedance parameters on various reflection coefficients is displayed in the form of a graph. From the present study, certain cases are also deduced.

Propagation of waves at an interface between a nonlocal micropolar thermoelastic rotating half-space and a nonlocal thermoelastic rotating half-space

The present investigation is concerned with the reflection and transmission phenomena of plane waves between a nonlocal micropolar thermoelastic rotating solid half-space and a nonlocal thermoelastic rotating solid half-space. Lord-Shulman’s theory has been employed in addressing mathematical analysis. There are four sets of reflected coupled waves in the medium and three sets of transmitted coupled waves in the medium , propagating with distinct speeds. Using appropriate boundary conditions, the amplitude and energy ratios for the reflected and transmitted waves are derived, and the numerical computations are carried out with the help of MATLAB software. The numerical values of the moduli of reflection and transmission coefficients are presented graphically to estimate and highlight the effects of micropolarity, angular velocity and nonlocal parameter. The expressions of energy ratios obtained in explicit form are shown graphically as a function of the angle of incidence. It has been verified that there is no loss of energy at the interface during reflection and transmission phenomena.

Numerical simulation of flow field characteristics and the improvement of pressure oscillation of rotating detonation engine

Due to the inherent working mode of rotating detonation engine (RDE), the detonation flow field has the characteristics of pressure oscillation and axial kinetic energy loss, which makes it difficult to design nozzle and improve propulsion performance. Therefore, in order to improve the characteristics of detonation flow field, the three-dimensional numerical simulation of annular chamber and hollow chamber is carried out with premixed hydrogen/air as fuel in this paper, and then tries to combine the two chambers to weaken the oscillation characteristics of detonation flow field through the interaction of detonation flow field, which is a new method to regulate the detonation flow field. The results show that there are four states of velocity vectors at the outlet of annular chamber and hollow chamber, which makes RDE be affected by rolling moment and results in the loss of axial kinetic energy. In the external flow field of combined chamber, the phenomenon of cyclic reflection of expansion wave and compression wave on the free boundary is observed, which results in Mach disk structure. Moreover, the pressure monitoring points are set at the external flow field. The pressure signal shows that the high-frequency pressure oscillation at the external flow field of the combined chamber has been greatly weakened. Compared to the annular chamber, the relative standard deviation (RSD) has been reduced from 14.6% to 5.6%. The results thus demonstrate that this method is feasible to adjust the pressure oscillation characteristics of the detonation flow field, and is of great significance to promote the potential of RDE and nozzle design.

Simulation Research on Air-Coupled Ultrasonic Detection of Layered Composite Interface Defects Using Matlab Computer Software

In this paper, a mathematical model and a finite element model are established to describe the dispersion characteristics of acoustic modes in a two-layer medium. Air-coupled ultrasound was used to detect interfacial defects in a laminated composite. An appropriate excitation signal was simulated to locate interface defects by both MATLAB (for the numerical model) and ANSYS (for the finite element model) software tools. The results confirmed that the mode of the excitation wave was consistent with the materials of the layered structure, which ensured propagation of the wave into each layer whereas avoiding the phenomenon of total reflection that prevents complete detection of the interfacial adhesive properties in the layered composite structure. This study demonstrates that the size of an interface defect should be simulated interchangeably using both MATLAB and ANSYS software. As such, it is feasible to detect the interfacial quality of laminated composites by air-coupled ultrasonic waves.

Cicada wing-inspired solar transmittance enhancement and hydrophobicity design for graphene-based solar steam generation: A novel gas phase deposition approach

The severe light reflection phenomenon has become a critical challenge for the sufficient utilization of solar energy. For preventing the predation risk, cicada’s wings are gradually evolved into transparent morphology to preferably blend into the natural environment. The high solar transmittance in cicada wings is due to the presence of surface micro/nanostructures which avoids the large change of refractive index between air and wings. Herein, inspired by the high solar transmittance of cicada’s wings, an extremely-simple gaseous phase deposition with low heating temperature is developed to cover graphene film with methyl-modified silicon dioxide (CH3-SiO2) nanospheres that decelerate the refractive index reduction. The destructive interference effect of CH3-SiO2 nanospheres effectively increases the solar transmittance to promote the absorption and conversion of solar energy into heat by graphene nanosheets. As a result, compared to pure graphene film, CH3-SiO2 nanospheres covered graphene (SiO2-graphene) film presents a temperature increase of ∼6.3 °C with solar illumination of 1.0 kW/m2. After being combined with zwitterion-modified cotton fabric, a novel solar steam generation system mainly composed of SiO2-graphene film is prepared. Due to the hydrophobicity of CH3-SiO2 nanosphere and the hydration effect of zwitterionic polymer, the salt precipitation and oil fouling problems regarded as major challenges in solar desalination are simultaneously solved, thus achieving water evaporation rate near 1.40 kg/m2h at oily seawater environment. Most importantly, the solar transmittance enhancement and anti-reflection design inspired by cicada wings provide a valuable reference to promote the solar absorption capacity of other photo-thermal conversion materials.

Understanding of controllable optical memory using 1D InP based photonic structures at three communication windows

The present research realises a controllable optical memory using one dimensional indium phosphate (InP) photonic structures at three optical communication windows (850, 1310 and 1550 nm). The photonic structures comprise 21 layers of InP and air material. The memory applications are realised at both single and dual signals of the communication windows. The physics of the research deals with the materials property including the variation of the refractive indices with respect to the input signal. Similarly, mathematics of the works relies on the analysis of reflectance, transmittance and absorbance phenomena. Further, the light from visible spectrum acts as triggering signal to realise optical memory applications. Finally, it is revealed that InP based photonic structures are suitable for controllable memory applications pertaining to the singlewavelength (850, 1310, 1550 nm) or dual wavelengths (850 and 1310 nm, 1310 and 1550 nm, 1550 and 850 nm).

Acoustic Feedback and Its Impact on Fan Flutter in Short Aeroengine Intakes

The authors have investigated pressure waves being emitted by the structural motion of a rotor blade and their impact on fan flutter sensitivity. This impact results from an acoustic feedback loop caused by reflection phenomena at the intake lip and may lead to a specific form of aeroelastic instability. Harmonic balance simulations of the fan/intake system over a wide operating range and blade eigenfrequencies were carried out. A significant impact on the rotor aerodynamic damping was observed as compared with the isolated rotor analysis due to the presence of the intake. This influence was either stabilizing or destabilizing, depending mainly on the phase relation between the emitted and reflected unsteady pressure fields. Computational fluid dynamics (CFD) data were analyzed accordingly, taking advantage of two-dimensional wave split as well as three-dimensional in-duct modal decomposition techniques. By deriving a simple analytical model based on eigenvalue analysis, a landscape showing regions of aerodynamic damping and excitation could be drawn over the investigated frequency–mass flow range. This analytical model and its verification with CFD data can help in identifying destabilizing areas at an early design stage, and hence support design decisions regarding flutter stability or give indications where analysis with higher fidelity is required.

Mathematical study on reflection and transmission of plane waves in a rotating piezo-thermo-elastic composite structure

The present investigation is concerned with the study of reflection and transmission characteristics of plane waves in two distinct rotating piezo-thermo-elastic substrates under the purview of dual-phase-lag (DPL) model and Lord–Shulman (LS) theory of thermo-elasticity. Mathematical expressions for electric displacements, stresses, amplitudes and energy ratios are derived. The influence of rotation on the amplitude ratios is extensively studied and comparative analyses are performed graphically among DPL and LS theories. Energy conservation law holds in the entire process of reflection and transmission phenomena. This study may be useful in the construction and design of temperature sensors and other piezoelectric surface-acoustic-wave devices.