Reflection Intensity Research Articles

Multi-mode fiber Bragg grating for simultaneous detection of strain, torsion and temperature

In this study, a fiber Bragg grating sensor utilizing multi-mode optical fiber (MM-FBG) is proposed. This sensor can simultaneously detect both temperature and torsion, or strain and torsion. Unlike single-mode fiber, the multiple modes of multi-mode fiber can generate several reflection peaks within the FBG area, increasing data capacity and enabling multi-parameter detection. By monitoring the center wavelength and reflection intensity of the MM-FBG reflection peaks, the sensor can detect temperature, torsion, and strain simultaneously. This approach simplifies parameter characterization compared to traditional methods, reducing signal interference and enhancing the clarity of experimental results. Experimental findings demonstrate that the MM-FBG sensor structure exhibits maximum sensitivities of 0.571 dBm/°/cm for torsion, 12 pm/°C for temperature, and 0.7411 pm/με for strain. Therefore, the fiber sensor proposed in this study shows great potential for monitoring bridge and tunnel structures and for civil engineering applications.

Python Indian Weather Radar Toolkit (pyiwr): An open-source Python library for processing, analyzing and visualizing weather radar data

The Python Indian Weather Radar Toolkit, abbreviated as "pyiwr", is an open-source Python library tailored for the purpose of handling data from the Indian Doppler Weather Radar (DWR). This paper provides a comprehensive overview of the pyiwr, which serves as a toolkit to read, analyze, process, and visualize weather radar data. Apart from this, the toolkit offers a range of robust functions implementing various algorithms covering several aspects of the radar data processing and quality control that facilitate the manipulation and analysis of weather radar data. To demonstrate the practical applicability of pyiwr, various case studies are presented, focusing on processing raw reflectivity data (clutter correction), Quantitative Precipitation Estimation (QPE) using Z-R relationship and time-series analysis of reflectivity and rain intensity, both spatially as well as at a specific location, during various meteorological events. This module enhances the accessibility and compatibility of radar data, enabling researchers, weather forecasters, and hydrologists to efficiently work with DWR data (particularly Indian DWR) that fosters advancements in weather radar research and applications. The open availability of pyiwr's source code on GitHub ensures that researchers and practitioners can not only access the toolkit but also contribute to its ongoing development.

Double-clad optical fiber as a single-point sensor of imaging quality for scanning laser system

We have developed a single-point optical sensor of imaging quality based on a double-clad optical fiber for laser beam scanning imaging systems. The optimal imaging quality, primarily affected by the accurate focusing, is determined by maximizing the ratio of the optical power coupled to the single-mode core and the inner multi-mode cladding of the double-clad fiber collecting the light scattered from the sample. We present simulations of the sensor’s performance at different levels of defocus and validate it experimentally by optimizing focus when imaging a scattering phantom and a living human eye with a scanning laser ophthalmoscope. In contrast to the existing image-based optimization procedures, our sensor provides feedback independent of illumination intensity or sample reflectivity that can be obtained for each image point, thus exceeding the imaging framerate. Importantly, our sensor can seamlessly be integrated with most laser scanning imaging systems, providing online feedback for correction optics.

P‐181: Enhancing the Bragg‐Reflection by Blending Ag Nanoparticles in Polymer Stabilized Cholesteric Liquid Crystals

The coupling between the incident light and the highly reflective nanoparticles is believed to potentially raise the reflective intensity of PSCLCs by creating a channel that causes the incident light to reach the helical CLCs and reflect outward. Therefore, in this research Ag nanoparticles were blended into polymer stabilized cholesteric liquid crystals (PSCLCs) to enhance their reflective intensity. A small amount of blending Ag nanoparticles (less than 1.0 wt%) in PSCLCs that investigated with 1wt% ‐ 3wt% RM 257 polymerization effectively leads to an increase of the reflective intensity of up to 17%, but has little effect on their thermally induced dynamical reflection variations. These results indicate that the blending of Ag nanoparticles in PSCLCs is an adequate method for the investigation of highly reflective PSCLCs.

Comparison of Nitriding Behavior for Austenitic Stainless Steel 316Ti and Super Austenitic Stainless Steel 904L

In situ X-ray diffraction (XRD) was used to compare nitrogen low-energy ion implantation (LEII) into austenitic stainless steel 316Ti and super austenitic stainless steel 904L. While the diffusion and layer growth were very similar, as derived from the decreasing intensity of the substrate reflection, strong variations in the observed lattice expansion—as a function of orientation, the steel alloy, and nitriding temperature—were observed. Nevertheless, a similar resulting nitrogen content was measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Furthermore, for some conditions, the formation of a double layer with two distinct lattice expansions was observed, especially for steel 904L. Regarding the stability of expanded austenite, 316Ti had already decayed in CrN during nitriding at 500 °C, while no such effect was observed for 904L. Thus, the alloy composition has a strong influence only on the lattice expansion and the stability of expanded austenite—but not the diffusion and nitrogen content.

Impact of cellular structure on the thickness and light reflection properties of structural color layers on diverse wood surfaces

ABSTRACT This study employed microsphere self-assembly to fabricate structural color layers on surfaces of seven woods. The wood cell structure, thickness of structural color layers, and optical reflection characteristics were analyzed. It was found that the main reflection wavelengths of structural color layers were all located at 490–500 nm. However, differences were observed in the reflection curves, as the thickness of structural color layers affected the width of reflection peak and the background reflection intensity. The water transport cells on wood surface are vessels in hardwood and tracheids in softwood. When they have larger diameters, higher numbers, and better internal patency, they can transport the emulsion, resulting in overflow and seepage. This reduced the number of microspheres, and led to thinner structural color layers with flatter and lower reflection peaks. The theoretical thickness of structural color layers were also calculated. By comparing the theoretical thickness of the structural color layers in two different crystal forms with the measured thickness, the influence of microsphere filling in vessels/tracheids and emulsion overflow on the thickness and optical reflection characteristics of the structural color layer was verified. This provides support for the development of controllable construction for structural color layers suitable for different woods.

Cationic pre-insertion interlayer engineering of manganese dioxide for highly efficient electromagnetic wave absorption

Interlayer engineering of two-dimensional structural materials provides unique advantages for tuning the electromagnetic properties of metal oxides, injecting unlimited energy into the design of advanced two-dimensional metal oxide electromagnetic wave absorbers. In this study, Manganese dioxide intercalated with alkali metal ions was prepared by a simple molten salt method. The pre-intercalation of ions not only enhances the polarization loss at the heterogeneous interface between cations (point sites) and manganese dioxide (face sites) but also alters the energy band structure of manganese oxide and enhances its electrical conductivity, which in turn enhances the conductive loss of the manganese dioxide. Due to the synergistic effect of multiple polarizations and conductive losses, NaMO exhibits superb electromagnetic wave absorption properties and an effective absorption bandwidth of 5.36 GHz at thinner matched thicknesses. In addition, the RCS simulation result further verifies the excellent electromagnetic wave absorption capability of NaMO. Under the positive incidence of electromagnetic waves, the electromagnetic wave reflection intensity of the metal plate coated with NaMO is effectively reduced. Finally, this work establishes a new way to modulate the electromagnetic properties.

Tunable spatial and angular spin splitting of reflected vortex-beam off hyperbolic metasurface

This paper investigated the spin splitting of the reflected beam with a vortex beam irradiating on a hyperbolic metasurface. This metasurface structure is the periodically rectangular-groove array on the surface of a hyperbolic crystal with the optical axis normal to its surface, where the array is a sub-wavelength biaxially hyperbolic grating with its periodical direction situated in the surface plane. Based on the hexagonal nitride boron crystal, we theoretically and numerically analyzed the spatial and angular spin splittings of the reflected beam, containing those produced by the transverse and longitudinal shifts. We found that the spatial shifts or spin splitting can be obtained in the first-order approximation of beam deflection, but the angular shifts can be described in the second-order approximation so that it enormously varies with the beam waist. Due to the hyperbolic anisotropy of the metasurface and the intrinsic orbital angular momentum in the incident beam, the expressions of spatial and angular shifts are effectively modified, and a unique double reflection effect occurs on the surface. Near certain reflective intensity distribution singularities, extremely asymmetrical spin splitting can be observed. These shifts and spin splitting can be tuned by varying the orientation of the incident plane and the angle of incidence.

Research on the fiber intensity modulation model of superconducting magnetic levitation rotor.

The measurement of the pole axis deviation angle of superconducting magnetic levitation rotors plays a crucial role in the field of high-precision navigation. This article conducts theoretical analysis and experimental research on the diffuse reflection intensity modulation principle of optical fiber sensors and the ideal diffuse reflection modulation model under ideal conditions. First, the structural distribution of optical fiber sensors is presented, and the principle of measuring the polar deviation angle of superconducting magnetic levitation rotors is analyzed. Then, based on the diffuse reflection intensity modulation principle, an optical fiber intensity modulation model for ideal superconducting magnetic levitation rotors is established. The correctness of this model was verified through simulation and calibration experiments, and the error between the simulation and experimental results was less than 8%.

OCT Intensity of the Region between Outer Retina Band 2 and Band 3 as a Biomarker for Retinal Degeneration and Therapy.

Optical coherence tomography (OCT) is widely used to probe retinal structure and function. This study investigated the outer retina band (ORB) pattern and reflective intensity for the region between bands 2 and 3 (Dip) in three mouse models of inherited retinal degeneration (Rs1KO, TTLL5KO, RPE65KO) and in human AMD patients from the A2A database. OCT images were manually graded, and reflectivity signals were used to calculate the Dip ratio. Qualitative analyses demonstrated the progressive merging band 2 and band 3 in all three mouse models, leading to a reduction in the Dip ratio compared to wildtype (WT) controls. Gene replacement therapy in Rs1KO mice reverted the ORB pattern to one resembling WT and increased the Dip ratio. The degree of anatomical rescue in these mice was highly correlated with level of transgenic RS1 expression and with the restoration of ERG b-wave amplitudes. While the inner retinal cavity was significantly enlarged in dark-adapted Rs1KO mice, the Dip ratio was not altered. A reduction of the Dip ratio was also detected in AMD patients compared with healthy controls and was also positively correlated with AMD severity on the AMD score. We propose that the ORB and Dip ratio can be used as non-invasive early biomarkers for retina health, which can be used to probe therapeutic gene expression and to evaluate the effectiveness of therapy.

The influence of hydrocarbons on the physical properties of sea bottom sediments of the Black Sea of different stages of diagenesis under conditions of high pressures and temperatures and the degree of saturation

The influence of hydrocarbons on the physical properties of sea bottom sediments of the Black Sea of different stages of diagenesis under conditions of high pressures and temperatures and the degree of saturation

Influence of Infrared Dry Heat Treatment on the Structure and Properties of Potato Starch

AbstractThe current study presents a novel approach to starch modification using infrared dry heat treatment (IR‐DHT). IR‐heating at 200 °C allows one to reduce the processing time to 15 min and does not lead to irreversible amorphization of starch structure. Upon IR‐DHT, an increase in density of starch granules from 1.4888 ± 0.0005 to 1.5038 ± 0.0005 g cm−3 is observed. The crystallinity degree of the starch exposed in water at 20 °C after IR‐DHT does not change compared to the crystallinity of native starch hydrated at the same temperature. However, the exposure in excess of water of native potato starch at 45 °C induces an increase of crystallinity up to 81% (along with a significant increase in the intensity of the d100 reflection), while heat‐treated starch exposed in water at the same temperature has reduced crystallinity (RC = 39%). In addition, the concentration of soluble carbohydrates released during the exposure process (45 °C, excess of water) increases by an order of magnitude for heat‐treated starch compared to the native sample. Hence, IR‐DHT may become a promising way to influence the processes of acid and enzymatic hydrolysis and control starch properties, such as pasting, solubility, and digestibility.

Focusing Algorithm of Range Profile for Plasma-Sheath-Enveloped Target

In this paper, a one-dimensional (1-D) range profile of the hypersonic target enveloped by a plasma sheath is investigated. Firstly, the non-uniform property of the plasma sheath is studied and its impact on the wideband electromagnetic (EM) wave is analyzed. A wideband radar echo model for the plasma-sheath-enveloped hypersonic target is constructed. Then, by exploiting the relationship among the incident depth, reflection intensity, and plasma velocity, it reveals that distinct scatter points in various areas of the target will suffer from varying reflection intensity and coupled velocity, leading to severe defocusing in the range profile. To tackle this issue, a novel focusing algorithm combing the Fractional Fourier Transform (FRFT) with the CLEAN technique is developed, which independently calculates the coupled plasma velocity and compensates for the phase error via a series of iterative procedures. Finally, the influence of the plasma sheath on the 1-D range profile and the effectiveness of the proposed focusing algorithm are validated through simulations.

Structural Color Materials with Color Mixing Effect Using Noble Metal‐Free Plasmonic Particles in SiO2–ZrN System

AbstractStructurally colored materials with a color mixing effect are developed using SiO2–ZrN core–shell particles, where ZrN nanoparticles used as shells exhibited localized surface plasmon resonances (LSPRs). ZrN nanoparticles (10–30 nm) are attached to monodispersed SiO2 particles by modifying SiO2 particles with polymers. The attached ZrN nanoparticles exhibited a plasmon resonance absorption band at 700 nm. These SiO2–ZrN core–shell particles have a highly monodisperse particle size and assemble into a particle‐stacked film with Bragg diffraction light in the visible spectrum. The particle‐stacked film of the SiO2–ZrN core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 core. The ratio of the reflection intensity in the long‐wavelength region corresponding to the ZrN absorption to that in the short‐wavelength region of the particle‐stacked film containing the ZrN shell is less than that of the ratio in only SiO2 particle‐stacked film. The results reveal that these particle‐stacked films exhibit a “color mixing effect” that combines specific wavelength absorption through plasmon resonance and specific wavelength diffraction owing to the periodic structure without using precious metals.

A PDMS-encapsulated cylindrical non-closed-packed photonic crystals composite with Bragg-enhanced Fresnel reflectance for optical gain and spectral selection

According to the Fresnel theory, the reflectivity intensity of spherical and cylindrical convex surfaces decreases from their edge to center, and it is noteworthy and interesting for optical gain to study the enhancement of center reflectance. In this paper, a polydimethylsiloxane (PDMS) − encapsulated cylindrical non-closed-packed photonic crystals (NPCs) composite with Bragg-enhanced Fresnel reflectance was designed for spectral selectivity and optical gain. Theoretically and experimentally, the periodically ordered structure of NPCs achieved high-reflection of light in photonic bandgap and high-transmission in other bands, which enhanced Fresnel reflectivity of the convex center to specific bands. Furtherly, the cylindrical NPCs hydrogel with stretchability was applied for the dynamic tuning of optical signals. The reflection peak of the PDMS-encapsulated cylindrical NPCs composite blue-shifted from 608 nm to 413 nm with 50 % tensile strain and achieved a rapid transition of structural color from orange to blue-violet in 60 cycles. The new kind of photonic crystals composite for optical gain and spectral selection broke through the limitations of traditional Fresnel curved mirrors with the lowest central reflectivity and inability to perform spectral selectivity, and have great significance and application prospects in fields of signal transmission, optical measurement, and instrument design.

An Improved Trilateral Localization Technique Fusing Extended Kalman Filter for Mobile Construction Robot

Semi-open and chaotic environments of building sites are considered primary challenges for the localization of mobile construction robots. To mitigate environmental limitations, an improved trilateral localization technique based on artificial landmarks fusing the extended Kalman filters (EKFs) is proposed in this paper. The reflective intensity of the onboard laser is employed to identify artificial landmarks arranged in the ongoing construction environment. A trilateral positioning algorithm is then adopted and evaluated based on artificial landmarks. Multi-sensor fusion, combined with the EKF, is included to improve the positioning accuracy and reliability of the robot in complex conditions. We constructed validation scenarios in the Gazebo simulation environment to verify the required localization functionality. Concurrently, we established simulated testing environments in real-world settings, where the practicality of the proposed technique was validated through the fitting of ideal and actual localization trajectories. The effectiveness of the proposed technique was corroborated through comparative experimental results.

СВОЙСТВА И ФАЗОВЫЙ СОСТАВ ЦЕМЕНТНЫХ РАСТВОРОВ

Introduction of complex antifreezes based on calcium formate, calcium chloride and superplasticizer Polyplast SP-1 into cement masses leads to changes in the phase composition of cement mortars. Of great importance are the developments of complex modifiers that are used for the hardening phase of cement-crushed mixtures, especially at low temperatures (down to –20 °C). The phase and structural characteristics of cement mortars have not been sufficiently studied. In this regard, the work investigated the effect of complex antifreeze additives on the properties and phase composition during the structuring of cement masses. Compressive strength reaches its maximum value (44.8 MPa) with the addition of calcium formate, calcium chloride and superplasticizer to the composition of cement pastes. X-ray diffraction analysis was carried out using a DRON-3 diffractometer. The used methods were standard. The X-ray diffraction patterns of the samples prove the high intensity of reflections of calcium hydrosilicate d = 9.69 Å, portlandite d = 4.921 Å, d = 2.632 Å, which indicates a high degree of hydration of portland cement. The combined use of calcium formate and calcium chloride promotes the activation of hydrolysis, and the addition of superplasticizer SP-1 leads to a decrease in the water-cement ratio to 0.20, which leads to an acceleration of the hardening process. Complex antifreeze additives increase the percentage ratio of crystalline phase to amorphous phase, thus, cement pastes with complex additives of 6 % (HCOO)2Ca, 3 % CaCl2, 2 % SP-1 have the highest value of degree of hydration (0.70) due to the formation of 63 % crystalline phase. Newly formed structures are typical for portlandite and dicalcium hydrosilicates. Complex antifreezes as an additive promote the activation of hydration in cement mortars, and the level of the degree of hydrolysis and the integral value of mass loss confirm this. Synergism of structure formation processes is observed at joint use of antifreeze additives in the composition of cement masses and, as a result, increases the strength of cement mortars used in construction at low climatic temperatures.

Algorithm for Point Cloud Dust Filtering of LiDAR for Autonomous Vehicles in Mining Area

With the continuous development of the transformation of the “smart mine” in the mineral industry, the use of sensors in autonomous trucks has become very common. However, the driving of trucks causes the point cloud collected by through Light Detection and Ranging (LiDAR) to contain dust points, leading to a significant decline in its detection performance, which makes it easy for vehicles to have failures at the perceptual level. In order to solve this problem, this study proposes a LiDAR point cloud denoising method for the quantitative analysis of laser reflection intensity and spatial structure. This method uses laser reflectivity as the benchmark template, constructs the initial confidence level template and initially screens out the sparse dust point cloud. The results are analyzed through the Euclidean distance of adjacent points, and the confidence level in the corresponding template is reduced for rescreening. The experimental results show that our method can significantly filter dust point cloud particles while retaining the rich environmental information of data. The computational load caused by filtering is far lower than that of other methods, and the overall operation efficiency of the system has no significant delay.

New methods for the identification of malachite pigments with varying particle sizes used in ancient Chinese murals by spectroscopic techniques

This study attempts to propose a simple, low-interventive and higher accuracy identification method for malachite pigments with varying particle sizes based on attenuated total reflection-Fourier transform infrared (ATR-FTIR), and evaluate the accuracy of ATR-FTIR and ultraviolet–visible near-infrared (UV-VIS-NIR) spectroscopy for identifying particle sizes. The micro-morphology, particle size, colour difference, and spectral characteristics of the malachite samples were determined using scanning electron microscopy (SEM), laser particle size analysis, colourimetry, UV-VIS-NIR and ATR-FTIR spectrometry. The principal component analysis (PCA) and mathematical models based on nonlinear curve fitting using UV-VIS-NIR and FTIR spectral data were developed and evaluated for the particle size identification of various malachite samples (pure malachite samples, fresh and aged malachite-rabbit glue samples). SEM morphological results showed that the malachite pigments with smaller particle sizes appear to have irregular flakes with a few loose agglomerated granules attached to the surface. The weight-specific surface area also increased gradually as the pigment particle size decreased. The colour difference results revealed that smaller malachite particle size gradually shifted toward the red–blue regions in CIE L*a*b* colour space. In addition, more intense reflectance and IR spectral absorbance peaks were observed in the case of the smaller particle size. The above proposed methods of particle size identification proved to be highly feasible and effective in predicting pigment particle size, which were confirmed by the PCA identification results and the mathematical model. Also, ATR-FTIR spectroscopy could provide more accurate predictions than UV-VIS-NIR spectroscopy, by keeping prediction errors below 5.5 μm.

Multi-Frequency GPR Data Fusion through a Joint Sliding Window and Wavelet Transform-Weighting Method for Top-Coal Structure Detection

Top-coal structure detection is an important basis for realizing effective mining in fully mechanized cave faces. However, the top-coal structure is very complex and often contains multi-layer gangues, which seriously influence the level of effective mining. For these reasons, this paper proposes a novel multi-frequency ground-penetrating radar (GPR) data-fusing method through a joint sliding window and wavelet transform weighting method to accurately detect the top-coal structure. It possesses the advantages of both high resolution and great detection depth, and it can also integrate multi-frequency GPR data into one composite profile to interpret the internal structure information of top coal in detail. The detection procedure is implemented following several steps: First of all, the multi-frequency GPR data are preprocessed and aligned through a band-pass filter and a zero offset elimination method to establish their spatial correspondences. Secondly, the proposed method is used to determine the time-varying weight values of each frequency GPR signal according to the wavelet energy proportion within the sliding window; also, the edge detection algorithm is introduced to improve the fusion efficiency of the wavelet transform so as to realize the effective fusion of the multi-frequency GPR data. Thirdly, a reflection intensity model of multi-frequency GPR signals traveling in the top-coal is established by using the stratified identification method, and then, the detailed top-coal structure can be inversely interpreted. Finally, the quantitative evaluation criteria, information entropy (IE), space–frequency (SF) and Laplacian gradient (LG), are used to evaluate the multi-frequency GPR data fusion’s effectiveness in laboratory and field environments. The experimental results show that, compared with the genetic, time-varying and wavelet transform fusion method, the fusion performance of the presented method possesses higher values in the IE, SF and LG evaluation criteria, and it also has both the merits of high resolution and great detection depth.