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Anomalies in reflection from periodic structures, well known in optics, result from either the transition from specular reflection to diffraction of light (Rayleigh's anomaly) or by coupling to the leaky surface mode supported by the structure (Wood's anomaly). Experimental observation and detailed analysis of both kinds of anomalies are presented here in the case of antisymmetric Lamb wave (A0) incidence at the 1D periodic structure located along the edge of the elastic plate. A structure with a strong phononic effect has been chosen, which enables the separation of both effects in terms of frequency. Another distinct feature of elastic waves in the periodic structure considered in this work is the existence of several localized modes, which leads to the multiple Wood's anomalies. Here, we report the experimental observation of double Wood's anomaly in addition to the Rayleigh's type of anomaly. [ABSTRACT FROM AUTHOR]

Sensing the interaction between the pilot and the control inceptors can provide important information about the pilot's activity during flight, potentially enabling the objective measurement of the pilot workload, the application of preventive actions against loss of situational awareness, and the identification of the insurgence of adverse couplings with the vehicle dynamics. This work presents an innovative pressure-sensing device developed to be seamlessly integrated into the grips of conventional aircraft control inceptors. The sensor, based on frustrated total internal reflection of light, is composed of low-cost elements and can be easily manufactured to be applicable to different hand pressure ranges. The characteristics of the sensor are first demonstrated in laboratory calibration tests. Subsequently, applications in flight simulator testing are presented, focusing on the objective representation of the pilot's instantaneous workload. [ABSTRACT FROM AUTHOR]

'Mercedes-star' quartz contains abundant long, narrow, randomly oriented rutile inclusions, and is notable for its unusual asterism. In particular, it displays weak three-rayed stars, with rays that meet at the centre as in the Mercedes-Benz emblem. In the classical theory of asterism such stars cannot exist, and they have not been seen in any other gem materials. We examined three samples (two spheres and one egg shaped) of 'Mercedes-star' quartz from Brazil. Ideally, this material displays six three-rayed stars located along two latitude planes parallel to the equatorial plane (perpendicular to the c-axis). In addition, six faint four-rayed stars are located along the equatorial plane. Therefore, in total, this quartz may display 18 stars located on three coaxial circles. The rays of all the stars consist of a path of reflective segments of unknown illumination origin, but which appear to result from double reflection of the light beam, first by Brazil-law twin planes and then by the rutile needles, making the phenomenon uncommon. In addition to the abovementioned stars seen in reflected light (epiasterism), more-transparent 'Mercedes-star' quartz may also show two six-rayed stars with transmitted light (diasterism) when illuminated from behind and viewed parallel to the c-axis. [ABSTRACT FROM AUTHOR]

This paper reports the study of some physical properties of thin films of tin oxide, such as the structural properties, surface morphology and optical transmission and reflection. The thin films of tin oxide were deposited by the method of thermal evaporation under vacuum. Transmission electron microscopy (TEM) was used to study the structural properties and the atomic force microscopy (AFM) method was used to study the surface morphology of thin films of tin oxide. The absorption and extinction coefficients of the investigated thin layers were determined from the transmittance and reflectance spectra recorded in the range of wavelengths between 190 and 1100 nm. [ABSTRACT FROM AUTHOR]

Three-dimensional background-oriented schlieren (3D-BOS) is an effective method for reconstructing 3D density fields from optically measured data, but it has limitations in measuring near-wall regions, where most of the light paths are blocked. This paper proposes a new extension, 3D-BOS using Mirror, which uses a wall as a mirror to provide sufficient light paths. In this paper, first, the conventional formulations are modified for the proposed method to handle the mirror reflections of the light paths. Subsequently, the proposed method is validated using artificially generated model data of an ideal axisymmetric distribution. The proposed method can reconstruct the distribution as accurately as the conventional method for all the number of cameras examined. Finally, the proposed method is experimentally demonstrated using a candle plume. The proposed method can capture cylindrical low-density regions near the wall surface. [ABSTRACT FROM AUTHOR]

Marine data products from the Ocean and Land Color Instrument (OLCI-A) operated onboard the Copernicus Sentinel 3A satellite, were assessed using in situ reference measurements representative of various European Seas. Results from the evaluation of spectral inherent optical properties indicated substantial accuracy for the satellite-derived absorption coefficient of pigmented particles $a_{\text {ph}}^{\text {OLCI-A}}(\lambda)$ , the diffuse attenuation coefficient of downward irradiance $K_{d}^{\text {OLCI-A}}(\lambda)$ , and the backscattering coefficient of marine particles $b_{\text {bp}}^{\text {OLCI-A}}(\boldsymbol {\lambda })$. Conversely, large underestimates were shown for the spectral absorption coefficient of non-water constituents $a_{\text {nw}}^{\text {OLCI-A}}(\lambda)$ and the cumulative absorption coefficient of colored dissolved organic matter and of non-pigmented particles $a_{\text {dg}}^{\text {OLCI-A}}(\lambda)$. [ABSTRACT FROM AUTHOR]

High-precision image matching techniques are required to fully utilize complementary information from optical and synthetic aperture radar (SAR) images. However, there are notable nonlinear radiometric differences (NRDs) between optical and SAR images because of the various imaging techniques used by the various sensors. The existing template matching method based on the Siamese structure underutilizes the phase structure information, which is less susceptible to NRD, resulting in subpar matching precision. To address this problem, this letter proposes an optical and SAR image-matching method based on phase structure convolutional features that use the log-Gabor filter (LGF) to extract the multiorientation phase structure information (MoPSI) of the image. It constructs a multiscale fusion SiamUNet-7 (MSF SiamUNet-7) network to extract the phase structure convolutional features to fully fuse the local texture information at a large scale and the global structure information at a small scale. The phase structure convolutional features of the optical and SAR images are used to generate the image pair similarity map using the mutual correlation layer, and the peak position in the similarity map is regarded as the best matching result. Experiments showed that, on the cropped Tiny-SEN1-2 dataset, the correct matching rate (CMR) and mean matching error (mME) of the threshold $T\le 4$ of the proposed method were 92.24% and 1.348, respectively, which improved the CMR($T\leq 4$) by 4.51% and reduced the mME by 0.046 compared with the original SiamUNet-9 model. The proposed method can effectively overcome the large NRD between the optical and SAR images and achieve high-precision matching. [ABSTRACT FROM AUTHOR]

Surfaces with light-trapping structures are widely used in solar cells to enhance light capturing and to transform efficiency. The study of light-trapping character is important for light-trapping structures in solar cells. In the present study, the light-trapping character for the regular hemisphere pit arrays (RHPAs) in solar cells was intensively investigated in terms of reducing light reflection, suppressing light escape, and increasing the length of the optical path. Results show that the RHPAs can decrease surface reflectivity by ~54% compared with the plane structure, and can reflect ~33% of the light that has not been absorbed back into the absorption layer of the solar cell. The total optical path of the cell with the RHPAs structure remarkably increased from 2ω to 4ω. To verify the theoretical research conclusions, we produced the glass structure samples with different aspect ratios by using micro/nanometer-processing technology. The reflection ratios for silicon wafers covered by plane and RHPAs glass samples were tested. The test results were compared with the theoretical calculation results, which showed consistency. [ABSTRACT FROM AUTHOR]

This paper presents a modified Bidirectional Reflectance Distribution Function (BRDF) model based on the Cauchy–Lorentz distribution that accurately characterizes the reflected energy distribution of typical materials, such as metals and coatings in hemispherical space. The proposed model overcomes the problem of large errors in classical models when detecting angles far away from the specular reflection angle by dividing the reflected light into specular reflection, directional diffuse reflection, and ideal diffuse reflection components. The newly added directional diffuse reflection component is represented by the Cauchy–Lorentz distribution, and its parameters are directly obtained from experimental measurement curves without distribution fitting. Surface morphology and model parameters are determined through measurements, and the comparison between simulation and actual measurement results shows that the modified BRDF model is in excellent agreement with the measured data. The proposed model not only achieves higher accuracy and universality, but it also represents a significant advancement in the field of BRDF modeling research. Its contributions have profound implications for advancing the state of the art in BRDF modeling, as well as having a broader impact on computer graphics and computer vision domains. [ABSTRACT FROM AUTHOR]

Raman distributed optical fiber temperature sensors possess the unique capability of measuring spatial environmental temperatures, which can be of great interest in several fields of application. The key physics barrier to spatial resolution for most optical time-domain reflection (OTDR) systems is the positioning principle of pulse-time-flight. It obtains the spatial resolution of the existing Raman distributed optical fiber temperature sensor, with the kilometer-level sensing distance being limited to the meter-level. Here, we propose a chaotic laser Raman distributed optical fiber temperature sensing scheme that replaces the traditional OTDR positioning principle used for more than 40 years with the chaotic correlation positioning principle. The proposed scheme possesses the characteristics of the chaos Raman scattering light excited by the chaos signal along the sensing fiber. A novel measurement mechanism based on chaotic time-domain differential reconstruction and chaotic correlation demodulation is developed, and a relationship between the temperature variation information and the chaotic correlation peak is experimentally demonstrated. Importantly, the proposed optics mechanism scheme overcomes the physics limitation of the effect of a wide pulse width on sensing spatial resolution; its spatial resolution is optimized from 50 to 0.3 m under the modulation of a 500 ns pulse width. This scheme provides a new concept for chaos optics and fiber sensing research. [ABSTRACT FROM AUTHOR]

Copyright of Forum Pedagogiczne / Pedagogical Forum is the property of Uniwersytet Kardynala Stefana Wyszynskiego w Warszawie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

GeSe monolayer (ML) has recently attracted much interest due to its unique structure and excellent physical properties that can be effectively tuned through single doping of various elements. However, the co-doping effects on GeSe ML are rarely studied. In this study, the structures and physical properties of Mn-X (X = F, Cl, Br, I) co-doped GeSe MLs are investigated by using first-principle calculations. The formation energy and phonon disspersion analyses reveal the stability of Mn-Cl and Mn-Br co-doped GeSe MLs and instability of Mn-F and Mn-I co-doped GeSe MLs. The stable Mn-X (X = Cl, Br) co-doped GeSe MLs exhibit complex bonding structures with respect to Mn-doped GeSe ML. More importantly, Mn-Cl and Mn-Br co-doping can not only tune magnetic properties, but also change the electronic properties of GeSe MLs, which makes Mn-X co-doped GeSe MLs indirect band semiconductors with anisotropic large carrier mobility and asymmetric spin-dependent band structures. Furthermore, Mn-X (X = Cl, Br) co-doped GeSe MLs show weakened in-plane optical absorption and reflection in the visible band. Our results may be useful for electronic, spintronic and optical applications based on Mn-X co-doped GeSe MLs. [ABSTRACT FROM AUTHOR]

The technology that can recognize the license plates of vehicles in real time and manage them automatically is a key element of building an intelligent transportation system. License plate recognition is the most important technique in vehicle image processing used to identify a vehicle. Object recognition using a camera is greatly influenced by environmental factors in which the camera is installed. When the vehicle image is acquired, the image is distorted due to the tilting of the license plate, reflection of light, lighting effects, rainy weather, and nighttime, so that it is difficult to accurately recognize the license plate. In addition, when the geometric distortion of the license plate image or the degradation of the image quality is intensified, it may be more difficult to automatically recognize the license plate image. Therefore, in this paper, we propose a deep learning–based vehicles' license plate recognition method to detect license plate and recognize characters accurately in complex and diverse environments. As a deep learning model, the YOLO model can be used to detect robust license plates in a variety of environments and to recognize characters quickly and accurately. It can also be seen that the license plate accurately recognizes the license plate with geometric distortion. [ABSTRACT FROM AUTHOR]

In this study, the photometry of a wide range of conventional and innovative pavements used in urban and interurban areas was characterised with a laboratory gonioreflectometer, both in new condition and after 30 months of natural ageing. An extreme diversity of behaviour with respect to light reflection has been demonstrated, both over time and between pavements. Various lighting studies have been carried out for cases of renewal of lighting installation with the installation of LED luminaires on poles in place. The calculations have shown that the use of typical CIE r -tables almost systematically leads to non-compliance with the EN 13201 standard, particularly in terms of uniformity. On the other hand, taking into account in the calculations, the photometry of the pavement in its stabilised state makes it possible both to respect the challenges of lighting safety and to achieve significant energy savings. As measurements of pavement photometry are rarely carried out, an alternative is to set up a database of urban pavements, which is one of the achievements of this research. [ABSTRACT FROM AUTHOR]

Emission, propagation, and reflection of light are mechanical phenomena; therefore, these phenomena are observed in an inertial frame as in the frame at absolute rest. At Cleveland Laboratory in 1924, Miller performed experiments with a Michelson interferometer employing local sources and sunlight. The fringe shift is zero in experiments such as the Michelson-Morley, where the source and mirrors are at rest in Earth's inertial frame, which explains Miller's experiments with local sources. When the source or/and mirrors are in motion in an inertial frame, there is a fringe shift. The Sun is an inertial frame at relative rest in which its light travels at the speed c in any direction, and Earth travels at the orbital speed v. This is the case of Miller's experiments with sunlight for which this article predicts an unobservable fringe shift in the range of 10 8. Thus, the Cleveland Laboratory experiments involving sunlight and local sources are explained. Miller's observed fringe shift of 0:08 in 1921 and 0:088 in 1925 at Mount Wilson remains unclear, leaving this subject open to theoretical and experimental challenges. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Spatial and temporal knowledge of temperature evolution is crucial in laser beam welding of low-melting materials such as aluminum alloys. Current temperature measurements are restricted to (i) one-dimensional temperature information (e.g., ratio-pyrometers), (ii) a priori knowledge of emissivity (e.g., thermography), and (iii) high-temperature regions (e.g., two-color-thermography). This study presents a ratio-based two-color-thermography system that enables acquiring spatially and temporally resolved temperature information for low-melting temperature ranges (<1200 K). The study demonstrates that temperature can be accurately determined despite variations in signal intensity and emissivity for objects emitting constant thermal radiation. The two-color-thermography system is further transferred into a commercial laser beam welding set-up. Experiments with varying process parameters are conducted, and the ability of the thermal imaging method to measure dynamic temperature behavior is assessed. Image artifacts presumably caused by internal reflections inside the optical beam path limit the direct application of the developed two-color-thermography system during dynamic temperature evolution. [ABSTRACT FROM AUTHOR]

Since the outbreak of COVID-19, as of January 2023, there have been over 670 million cases and more than 6.8 million deaths worldwide. Infections can cause inflammation in the lungs and decrease blood oxygen levels, which can lead to breathing difficulties and endanger life. As the situation continues to escalate, non-contact machines are used to assist patients at home to monitor their blood oxygen levels without encountering others. This paper uses a general network camera to capture the forehead area of a person's face, using the RPPG (remote photoplethysmography) principle. Then, image signal processing of red and blue light waves is carried out. By utilizing the principle of light reflection, the standard deviation and mean are calculated, and the blood oxygen saturation is computed. Finally, the effect of illuminance on the experimental values is discussed. The experimental results of this paper were compared with a blood oxygen meter certified by the Ministry of Health and Welfare in Taiwan, and the experimental results had only a maximum error of 2%, which is better than the 3% to 5% error rates in other studies The measurement time was only 30 s, which is better than the one minute reported using similar equipment in other studies. Therefore, this paper not only saves equipment expenses but also provides convenience and safety for those who need to monitor their blood oxygen levels at home. Future applications can combine the SpO2 detection software with camera-equipped devices such as smartphones and laptops. The public can detect SpO2 on their own mobile devices, providing a convenient and effective tool for personal health management. [ABSTRACT FROM AUTHOR]

Several biochars were synthesized from olive stones and used as supports for TiO2, as an active semiconductor, and Pt as a co-catalyst (Pt/TiO2-PyCF and Pt/TiO2-AC). A third carbon-supported photocatalyst was prepared from commercial mesoporous carbon (Pt/TiO2-MCF). Moreover, a Pt/TiO2 solid based on Evonik P25 was used as a reference. The biochars used as supports transferred, to a large extent, their physical and chemical properties to the final photocatalysts. The synthesized catalysts were tested for hydrogen production from aqueous glycerol photoreforming. The results indicated that a mesoporous nature and small particle size of the photocatalyst lead to better H2 production. The analysis of the operational reaction conditions revealed that the H2 evolution rate was not proportional to the mass of the photocatalyst used, since, at high photocatalyst loading, the hydrogen production decreased because of the light scattering and reflection phenomena that caused a reduction in the light penetration depth. When expressed per gram of TiO2, the activity of Pt/TiO2-PyCF is almost 4-times higher than that of Pt/TiO2 (1079 and 273 mmol H2/gTiO2, respectively), which points to the positive effect of an adequate dispersion of a TiO2 phase on a carbonaceous support, forming a highly dispersed and homogeneously distributed titanium dioxide phase. Throughout a 12 h reaction period, the H2 production rate progressively decreases, while the CO2 production rate increases continuously. This behavior is compatible with an initial period when glycerol dehydrogenation to glyceraldehyde and/or dihydroxyacetone and hydrogen predominates, followed by a period in which comparatively slower C-C cleavage reactions begin to occur, thus generating both H2 and CO2. [ABSTRACT FROM AUTHOR]

A broadband absorber with high optical transparency is proposed and realized using an optimization-designed method. The absorber's reflection, lossy, and dielectric layers are considered for obtaining high optical transparency. First, to maintain microwave absorption, the artificial structures of the reflection layer are designed on the micron scale. Low square resistance and high optical transparency are achieved simultaneously. Then, considering the artificial structure fabrication process [fabricated on polyethylene terephthalate (PET)], high light transmittance polymethyl methacrylate (PMMA) was selected as the material of the dielectric layer. The permittivity of PMMA is similar to that of PET. The light reflection of layer-to-layer is reduced, and the light transmittance is improved. Finally, under the same microwave absorption band and absorption efficiency, the topology structures of the lossy layer are optimized to increase the duty ratio and the light transmittance. Through the above-mentioned design, high optical transparency and broadband microwave absorption are achieved simultaneously. The simulated and measured results prove that more than 90% of the absorption rate is obtained from 4.4 to 11.5 GHz (89.3%) and the average light transmittance reached 80%. The results verify the optimization-designed method's effectiveness and provide technical support for transparent absorbers to be better applied to optical windows. [ABSTRACT FROM AUTHOR]

A lab-scale parallel photoreactor model has been developed for broad applications in organic chemistry. Position, angle, and distance in the reactor are systematically optimized for achieving high reproducibility under the guidance of the Inverse Square Law and Lambert's Cosine Law, which were first applied in the design of the photoreactor. Improvement of photon efficiency is realized via 3-point irradiation and broad-band light reflector of aluminum. Photon flux is measured with an optical power meter with its display and adjustment suggested being integrated into the photoreactor for the first time. [ABSTRACT FROM AUTHOR]

Copyright of Revista Góndola, Enseñanza y Aprendizaje de las Ciencias is the property of Gondola, Ensenanza y Aprendizaje de las Ciencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two-dimensional (2D) van der Waals (vdW) magnetic materials with strong in-plane anisotropy can make possible novel applications such as optospintronics and strain sensors. In this work, the strong in-plane optical anisotropy in 2D vdW antiferromagnet VOCl has been systematically investigated. The optical brightness and absorption coefficient exhibit evident periodic variation with the change of incident polarization, unveiling the strong in-plane anisotropic optical absorption. The Raman intensity in this material shows obvious dependence on the polarization angle of incident laser, demonstrating that the phonon properties possess strong in-plane anisotropy. Besides, we have also realized in-situ visualization of in-plane optical reflection anisotropy in this material. Moreover, the strong second harmonic generation (SHG) signal can only be detected when the incident polarization is along specific in-plane crystal orientations, illustrating the presence of strong in-plane nonlinear optical anisotropy. These findings will benefit the applications of VOCl in the field of polarization-dependent electronics and spintronics. [ABSTRACT FROM AUTHOR]

Exceptional points, where eigenvalues and eigenvectors coalesce, impact the behavior of different photonics components that show, e.g., enhanced sensing, coherent perfect absorption, unidirectional lasing, and chirality. However, only a few passive geometries have been developed that work on these points. Here, we introduce a novel non-Hermitian structure based on a microresonator shaped as the infinity symbol twice coupled to a bus waveguide: the infinity-loop microresonator. Unlike other structures working on an exceptional surface, the infinity-loop microresonator can achieve either high- or low-contrast unidirectional reflection with a negligible or identical reflection for counterpropagating light. It allows an easy walking through the Riemann sheet by simply controlling the phase of the light propagating in the bus waveguide, which makes it a tunable component to build more complex topological structures. Furthermore, the infinity-loop microresonator allows sensors that show the features of both an exceptional point device and a diabolic point device simultaneously. [ABSTRACT FROM AUTHOR]

Since the light is absorbed, reflected and scattered during the transmission process, underwater images are degraded suffering from color casts and low contrast. In the paper, an effective enhancement method for single underwater image is proposed based on the reconstruction technique from gradients. The method firstly corrects color by a simple and effective white-balancing approach after the compensation of red attenuation. And then an improved DCP method is used to estimate the transmission indicating the absorption and reflection of light, based on a combination filter because of edge preservation and high efficiency. Last, the enhanced gradients are obtained based on the estimated transmission, and details enhancement is accomplished by image reconstruction from the enhanced gradients on the luminance layer in Lab color space. Experimental results show that our method achieves better visual results in qualitative and quantitative evaluation, which can effectively recover the color and improve the image contrast even in very dense regions. Additionally, running time shows that our method is competitive and can be applied for real-time tasks. [ABSTRACT FROM AUTHOR]

Water segmentation is a critical task for ensuring the safety of unmanned surface vehicles (USVs). Most existing image-based water segmentation methods may be inaccurate due to light reflection on the water. The fusion-based method combines the paired 2D camera images and 3D LiDAR point clouds as inputs, resulting in a high computational load and considerable time consumption, with limits in terms of practical applications. Thus, in this study, we propose a multimodal fusion water segmentation method that uses a transformer and knowledge distillation to leverage 3D LiDAR point clouds in order to assist in the generation of 2D images. A local and non-local cross-modality fusion module based on a transformer is first used to fuse 2D images and 3D point cloud information during the training phase. A multi-to-single-modality knowledge distillation module is then applied to distill the fused information into a pure 2D network for water segmentation. Extensive experiments were conducted with a dataset containing various scenes collected by USVs in the water. The results demonstrate that the proposed method achieves approximately 1.5% improvement both in accuracy and MaxF over classical image-based methods, and it is much faster than the fusion-based method, achieving speeds ranging from 15 fps to 110 fps. [ABSTRACT FROM AUTHOR]

Structural, electronic, and optical properties of a new combined system of carbon and boron nitride nanotubes are studied using the DFT first principles as implemented in Quantum ESPRESSO codes. The corrections to the quasi-particle energies were studied via GW hybrid functional implemented in the YAMBO code within the many-body perturbation theory. The studies were performed under different interwall distances of 3.0 nm, 2.5 nm, and 1.5 nm between CNTs and BNNTs. The results showed that the structural properties demonstrated high stability of the double-walled carbon boron nitride nanotube (DWCBNNT) systems under interwall distance (IWD) of 3.00 nm, 2.50 nm, and 1.50 nm. Results also demonstrated an inverse variation between the IWD and the diameter of the DWCBNNT system. In terms of the electronic properties, all three configurations of the DWCBNNTs reveal semiconducting behavior under KS-DFT showing a direct band gap of 3.30 eV, 1.79 eV, and 0.81 eV under IWD of 3.0 nm, 2.5 nm, and 1.5 nm, respectively. Furthermore, the band gap of the DWCBNNT increases with an increase in IWD (decrease in inner tube diameter) and decreases with a decrease in IWD (increase in inner tube diameter). In all three cases, the bands are formed by the molecular orbitals of the armchair CBNNT which are transformed to a series of continuous energy levels; the behaviors of electrons that formed the heterostructure are related to the behavior of electrons in B, C, and N atoms. From the optical properties perspective, the studies were conducted in parallel and perpendicular directions to the nanotubes' axes. The presence of static dielectric functions in parallel direction at 3.3, 3.4, and 4.5 for nanotubes under 3.0 nm, 2.5 nm, and 1.5 nm demonstrated optical refraction. Refractions were also observed in directions perpendicular to the nanotubes. Furthermore, optical reflections occur when there is a higher absorption. The ability of these CBNNT hybrid systems to refract in all directions revealed the most exciting properties of the armchair CBNNT suitable to be used in magnifying glass materials. The findings further imply that the optical absorption coefficient is inversely related to the diameter of the nanotubes and is directly correlated to the band gap. [ABSTRACT FROM AUTHOR]

The reflection of light from distributed microplatelets is an effective approach to creating color and controlling the optical properties in paints, security features, and optical filters. However, predictive tools for the design and manufacturing of such composite materials are limited due to the complex light–matter interactions that determine their optical response. Here, the optical reflectance of individual reflective microplatelets and of polymer‐based composites containing these engineered platelets as an aligned, dispersed phase are experimentally studied and analytically calculated. Transfer‐matrix calculations are used to interpret the effect of the platelet architecture, the number of platelets, and their size distribution on the experimentally measured reflectance of composites prepared using a previously established magnetic alignment technique. It is demonstrated that the reflectance of the composites can be understood as the averaged response of an array of Fabry–Pérot resonators, in which the microplatelets act as semi‐transparent flat reflectors and the polymer as cavity medium. By using an analytical model and computer simulations to describe the interaction of light with platelets embedded in a polymer matrix, this work provides useful tools for the design and fabrication of composites with tailored optical reflectance. [ABSTRACT FROM AUTHOR]

Strabismus is a common ophthalmologic disease that affects approximately 1.19% to 5.0% of children; however if the disease is detected early it can be treated effectively. Generally, the automatic detection of strabismus is usually performed only by a single feature, which is, with image deep features or ratio features. However, the accuracy of a strabismus diagnosis with a single feature is unreliable. This study aims to develop an intelligent strabismus detection model driven by corneal light reflection photographs to automatically detect children's strabismus. The proposed multi‐feature fusion model (MFFM) improves the detection performance by fusing the deep features and ratio features extracted from the corneal light reflection photographs to identify strabismus. The experimental results demonstrate that our proposed multi‐feature model outperforms all of the single feature models in strabismus detection. The experiments show that the proposed method achieves an accuracy of 97.17%, sensitivity of 96.06%, specificity of 97.79%, and AUC of 0.969 in strabismus detection. Our evidence shows that it greatly improves the performance of strabismus detection. [ABSTRACT FROM AUTHOR]

A learning sequence from the Interdisciplinary Mathematics and Science (IMS) learning project is presented. A problem was posed for Grade 4/5 students to explore the path and reflection of light: "Can we see things over a tall wall or around the corners of a building?". [ABSTRACT FROM AUTHOR]

Time-varying materials bring an extra degree of design freedom compared to their conventional time-invariant counterparts. However, few discussions have focused on the underlying physical difference between spatial and temporal boundaries. In this letter, we thoroughly investigate those differences from the perspective of conservation laws. By doing so, the building blocks of optics and electromagnetics such as the reflection law, Snell's law, and Fresnel's equations can be analogously derived in a temporal context, but with completely different interpretations. Furthermore, we study the unique features of temporal boundaries, such as their nonconformance to energy conservation and causality. [ABSTRACT FROM AUTHOR]

A method for welding line detection using point cloud data is proposed to automate welding operations combined with a contact sensor. The proposed system targets a fillet weld, in which the joint line between two metal plates attached vertically is welded. In the proposed method, after detecting the position and orientation of two flat plates regarding a single viewpoint as a rough measurement, the flat plates are measured from the optimal shooting position in each plane in detail to detect a precise weld line. When measuring a flat plate from an angle, the 3D point cloud obtained by a depth camera contains measurement errors. For example, a point cloud measuring a plane has a wavy shape or void owing to light reflection. However, by shooting the plane vertically, the point cloud has fewer errors. Using these characteristics, a two-step measurement algorithm for determining weld lines was proposed. The weld line detection results show an improvement of 5 mm compared with the rough and precise measurements. Furthermore, the average measurement error was less than 2.5 mm, and it is possible to narrow the range of the search object contact sensor for welding automation. [ABSTRACT FROM AUTHOR]

Polymer-stabilised cholesteric liquid crystal (PSCLC) films with selective circularly polarised light reflection have attracted much attention for their applications as polarisers, energy-saving windows and for displays. Herein, CLC mixtures were prepared using a nematic LC LC242 and a chiral compound S-6 with enantiotropic SmA and SmC* phases, which exhibited a cholesteric phase with a smectic order. After photopolymerisation, the PSCLC films with fingerprint structure at the surfaces and supramolecular helical structure inside were obtained. Due to the existence of shortrange smectic order in the cholesteric structure, the Bragg reflection bands were broadened. For a CLC mixture, with increasing temperature, the short-range smectic order was suppressed, and the selective Bragg reflection band shifted to the short wavelength. Based on this thermochromic behaviour, colourful PSCLC patterns and gratings were prepared, which were able to be applied in decoration and anti-counterfeiting. Since the PSCLC films can be obtained within several seconds under air, large-area films can be prepared on coating lines at low-cost. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microbottle resonators (MBR) are bottle-like structures fabricated by varying the radius of an optical fiber. MBRs can support whispering gallery modes (WGM) by the total internal reflection of the light coupled into the MBRs. MBRs have a significant advantage in sensing and other advanced optical applications due to their light confinement abilities in a relatively small mode volume and having high Q factors. This review starts with an introduction to MBRs' optical properties, coupling methods, and sensing mechanisms. The sensing principle and sensing parameters of MBRs are discussed here as well. Then, practical MBRs fabrication methods and sensing applications are presented. [ABSTRACT FROM AUTHOR]

Multi-view observations provide complementary clues for 3D object recognition, but also include redundant information that appears different across views due to view-dependent projection, light reflection and self-occlusions. This paper presents a view-relation constrained global representation network (VCGR-Net) for 3D object recognition that can mitigate the view interference problem at all phases, from view-level source feature generation to multi-view feature aggregation. Specifically, we determine inter-view relations via LSTM implicitly. Based on the relations, we construct a two-stage feature selection module to filter features at each view according to their importance to the global representation and their reliability as observations at specific views. The selected features are then aggregated by referring to intra- and inter-view spatial context to generate global representation for 3D object recognition. Experiments on the ModelNet40 and ModelNet10 datasets demonstrate that the proposed method can suppress view interference and therefore outperform state-of-the-art methods in 3D object recognition. [ABSTRACT FROM AUTHOR]

Contrast ratio is the ratio of the brightest part to the darkest part of the image, which can reflect the picture hierarchy. In VR head‐mounted display (HMD), many scenes need to realistically simulate rooms or night environments. High contrast ratio helps to better display details in dark scenes, giving people the ultimate sense of immersion. There are many ways to measure contrast ratio, but still no effective standard to evaluate this indicator. In particular, many VR HMD adopt the emerging solution of folded optical path pancake. Due to the refraction and reflection of light on different interfaces, the pancake module will cause "ghosting", then affect the visual experience. Therefore, it becomes our focus to evaluate the contrast ratio of pancake VR HMD. We present a way to evaluate the contrast ratio of VR HMD by a near‐eye display measurement system, and compares the measurement results of different test methods. It can systematically and objectively evaluate the contrast of VR head‐mounted display devices and provide a useful reference for VR device evaluation. [ABSTRACT FROM AUTHOR]

Photoelectrochemical photocurrent switching (PEPS) effect can regulate the polarity of photocurrent, which has significant potential applications in areas such as logic gates, photosynapse, and artificial intelligence. In this work, it is reported for the first time that a pure Ga2O3 photoelectrochemical system exhibits ambipolar photocurrent behavior induced by deep ultraviolet, which is closely linked to the crystalline phase of Ga2O3 (α or β) and the surface states of oxygen vacancies. Spongy porous nanorod arrays (NRAs) of Ga2O3 designed here not only increase the contact area of Ga2O3 with the electrolyte but also can lower largely the reflection of light and improve light‐trapping capacity. For α phase Ga2O3, the photocurrent is in a forward direction under positive bias and shows a backward direction under negative bias in NaOH solution, exhibiting a distinct ambipolar photocurrent phenomenon, which can be attributed to more oxygen vacancy surface states and lower potential barrier at the semiconductor/electrolyte interface. Furtherly, the effect of the surface states on the ambipolar photocurrent behavior of α‐Ga2O3 NRAs is demonstrated by various treatment times of oxygen plasma, whose switching point moves from 0 V to −0.19 V with treatment for 30 min and continues to move in the negative direction with the increase of treatment time. Moreover, based on the ambipolar photocurrent behavior of α‐Ga2O3 NRAs, adjustable Boolean logic gates with voltage are prepared as the input source, offering a new path for the photoelectric device multifunctional integration needed in the Post‐Moore era, with a high accuracy manipulated by solar‐blind deep ultraviolet light. [ABSTRACT FROM AUTHOR]

Field biology courses—which expose students to concepts through outdoor experimentation and observation—are a staple in undergraduate natural science education. Participation in field courses has been associated with increased academic success, retention, and strengthening of science identity. However, for some students, learning outdoors can pose barriers to comfort, enjoyment, and success and may contribute to alienation and attrition. To better understand the kinds of challenges encountered by students and how those experiences might vary by student demographics and prior experience, we analyzed journal reflections from undergraduates in an introductory field biology course using a mixed‐methods approach. We used open coding to characterize the challenges that students described and found that students identified challenges related to four categories: (1) scientific challenges, concerning concepts, field methods, and data; (2) logistic challenges, relating to factors such as the timing of the course and equipment; (3) conditions challenges, regarding difficulties with organisms, the environment, and inclement weather; and (4) additional challenges, encompassing a broad array of student difficulties. Using multilevel binomial modeling, we examined the effect of course factors (e.g., field lab topic and section) and student factors (e.g., demographics and prior outdoor experience) on the occurrence of each type of challenge within journal reflections. Field lab topic was the only effect likely to increase the presence of all four types of challenges for students. In addition, students with the most prior outdoors experience were less likely to report a logistic challenge compared with their peers in the course who had less outdoors experience. Based on our findings, we offer recommendations for how instructors can support students through challenges they face in introductory field biology. [ABSTRACT FROM AUTHOR]

Nanorings (NRs) with their intrinsic cavities have attracted interest as plasmonic nanoparticles for years, due to the uniform electric field enhancement inside the cavity, lower plasmon damping effects and comparatively high refractive index sensitivities. In the present work, we successfully fabricated a series of Au NR arrays on flexible polydimethylsiloxane substrates by taking advantage of state-of-the-art fabrication methods such as electron beam lithography and wet-etching transfer techniques. In-situ optical measurements on these flexible systems are enabled by implementing a homemade micro-stretcher inside an optical reflection spectroscopy setup. The corresponding dark-field spectra of thin-walled NR arrays exhibit a strong shift to longer wavelengths (i.e., ~ 2.85 nm per 1% strain) under polarization perpendicular to the traction, mainly resulting from the increasing shape deformation of the NRs under strain. Moreover, numerical simulations illustrate that the shifting plasmonic mode has a radially-symmetric charge distribution of the bonding mode and is rather sensitive to the tuning of the NRs' shape as confirmed by a subsequent in-situ scanning electron microscope characterization. These results explore the possibilities of shape-altering flexible plasmonics for nanoparticles with a cavity and indicate potential applications for plasmonic colors and biochemical sensing in future work. [ABSTRACT FROM AUTHOR]

The design of new materials for non-contact temperature sensors is an important task for scientists working in the fields of chemistry, physics, and materials science. In the present paper, a novel cholesteric mixture based on a copolymer doped with a highly luminescent europium complex was prepared and studied. It was found that the spectral position of the selective reflection peak strongly depends on temperature and a shift towards shorter wavelengths is observed upon heating with an amplitude of more than 70 nm, from the red to green spectral range. This shift is associated with the existence and melting of clusters of smectic order, as confirmed by X-ray diffraction investigations. The extreme temperature dependence of the wavelength of selective light reflection provides a high thermosensitivity of the degree of circular polarization of the europium complex emission. The highest values of the dissymmetry factor are observed when the peak of selective light reflection fully overlaps with the emission peak. As a result, the highest sensitivity of 65%/K for luminescent thermometry materials was obtained. In addition, the ability of the prepared mixture to form stable coatings was demonstrated. The obtained experimental results, i.e., the high thermosensitivity of the degree of circular polarization, and the ability to form stable coatings allow us to consider the prepared mixture as a promising material for luminescent thermometry. [ABSTRACT FROM AUTHOR]

A novel design of crossed compound parabolic concentrator (CCPC) that has a rectangular entry aperture is presented, which has the advantage of considerably improved angular response compared to a conventional CCPC that has a square entry aperture. It is found that the half acceptance angle of this novel design is 40° for a 4.0x rectangular concentrator when operating in the "east-west" direction, which is approximately 10° larger than that of a conventional square concentrator of the same concentration ratio. This is a substantial increase and completely unexpected because the design theory for this type of concentrators predicted a much smaller half acceptance angle of 26.6°. Experimental and simulation work reported in this paper confirms this discovery. The results reveals that the observed improvement is attributed to multiple light reflection inside the concentrator, which was not considered in the commonly employed design theory. An important implication of this work is that the multiple light reflection plays an important role in the angular response of the CCPC and its effect cannot be neglected in the design. [ABSTRACT FROM AUTHOR]

Lithium (2 wt.%)-doped cadmium oxide (CdO:Li) film was grown on a glass substrate via a sol-gel processed screen-printing set-up. Through X-ray diffraction, it was demonstrated that the CdO:Li film exhibits reflections from the (111), (200), (220), (311), and (222) CdO cubic phase planes. The SEM image showed irregularly shaped, interconnected, and agglomerated grains on the entire film. The optical diffuse reflection study revealed that the film has a direct transition of the band gap at 2.50 eV. The refractive index of the film varies with photon energy and gains maximum value (~2.3) at 1.5 eV. The electrical attributes of the film were inspected by Hall measurement. It was noticed that the film conveyed n-type conductivity with low resistivity of the order of 10–3 Ω·cm. [ABSTRACT FROM AUTHOR]

Background: The purpose of the study was to evaluate the changes of light reflection% on two materials (monolithic zirconia and lithium disilicate) after using two external staining kits following by thermocycling. Methods: Specimens were sectioned from monolithic zirconia (n = 60) and lithium disilicate (n = 60) then divided into six groups (n = 20). Two different types of external staining kits were used and applied to the specimens. The light reflection% was measured before staining, after staining and after thermocycling using a spectrophotometer. Results: The light reflection% of zirconia was significantly higher compared to lithium disilicate at the beginning of the study (p = 0.005), after staining with kit 1 (p = 0.005) and kit 2 (p = 0.005) and after thermocycling (p = 0.005). For both materials, the light reflection% was lower after staining with Kit 1 compared to kit 2 (p < 0.043). After thermocycling, the light reflection% of lithium disilicate increased (p = 0.027) and was unchanged with Zirconia (p = 0.527). Conclusions: There is a difference between the materials regarding light reflection% as the monolithic zirconia showed higher light reflection% comparing lithium disilicate throughout the entire experiment. For lithium disilicate, we recommend using kit 1 as we found that, after thermocycling, the light reflection% of kit 2 was increased. [ABSTRACT FROM AUTHOR]

A classical wave–particle entity (WPE) can be realized experimentally as a droplet walking on the free surface of a vertically vibrating liquid bath, with the droplet's horizontal walking motion guided by its self-generated wave field. These self-propelled WPEs have been shown to exhibit analogs of several quantum and optical phenomena. Using an idealized theoretical model that takes the form of a Lorenz-like system, we theoretically and numerically explore the dynamics of such a one-dimensional WPE in a sinusoidal potential. We find steady states of the system that correspond to a stationary WPE as well as a rich array of unsteady motions, such as back-and-forth oscillating walkers, runaway oscillating walkers, and various types of irregular walkers. In the parameter space formed by the dimensionless parameters of the applied sinusoidal potential, we observe patterns of alternating unsteady behaviors suggesting interference effects. Additionally, in certain regions of the parameter space, we also identify multistability in the particle's long-term behavior that depends on the initial conditions. We make analogies between the identified behaviors in the WPE system and Bragg's reflection of light as well as electron motion in crystals. [ABSTRACT FROM AUTHOR]

Hydroxypropyl cellulose (HPC) derivatives with alkanoyl side chains are known to form thermotropic cholesteric liquid crystals (CLCs) with visible reflection. Although the widely investigated CLCs are requisite for tedious syntheses of chiral and mesogenic compounds from precious petroleum resources, the HPC derivatives easily prepared from biomass resources would contribute to the realization of environment-friendly CLC devices. In this study, we report the linear rheological behavior of thermotropic CLCs of HPC derivatives possessing alkanoyl side chains of different lengths. In addition, the HPC derivatives have been synthesized by the complete esterification of hydroxy groups in HPC. The master curves of these HPC derivatives were almost identical at reference temperatures, with their light reflection at 405 nm. The relaxation peaks appeared at an angular frequency of ~102 rad/s, suggesting the motion of the CLC helical axis. Moreover, the dominant factors affecting the rheological properties of HPC derivatives were strongly dependent on the CLC helical structures. Further, this study provides one of the most promising fabrication strategies for the highly oriented CLC helix by shearing force, which is indispensable to the development of advanced photonic devices with eco-friendliness. [ABSTRACT FROM AUTHOR]

Light has a fascinating property: it always travels the path that takes the least time between any two points. This is the motivating property behind optical phenomena such as reflection and refraction. The unreasonable economic efficiency of light is captured by a single proposition: the principle of least action (PLA) in optics. Unlike reflection and refraction, which emerge from optimizing a one-dimensional function, the PLA emerges from optimizing an infinite-dimensional functional. The PLA can be difficult for students to comprehend, as the formulation of the Lagrangian is often left unexplained. To this end, this paper presents various simulations to demonstrate the action principle, including a numerical solution to a generalization of the brachistochrone problem to an arbitrary refractive profile. The interactive simulations discussed in the paper are available at Ref. 1. [ABSTRACT FROM AUTHOR]

This work is devoted to the effect of pulse hydrogen saturation on a gold film on glass used as a surface plasmon resonance sensor of the "Plasmon-6" spectrophotometer. Due to electrolysis in a 10 % solution of H2SO4 in water, the film was saturated with hydrogen. The surface of the gold film was the cathode, and the carbon electrode was the anode. Electrolysis current pulses lasted 2 s when the time interval between pulses was 1800 s. In this way, several samples were processed. The consequences of the action of five, ten, fifteen and twenty pulses on a gold film were examined as the experimentally obtained spectral curves for treated samples. The surface plasmon resonance is sensitive to changes occurring in the surface layer of the surface plasmon resonance sensor. It is applicable to control and analyze the changes induced by the proposed hydrogen treatment. In the experiments, the plasmon resonance curves shifted to larger angles. Therefore the optical properties modifications of the surface layer of the gold film were recorded. The observed changes gradually increased with the increase of the number of pulses of the electrolysis current. The mathematical approach to light reflection from the gold film was performed to analyze changes in the surface layer of the gold film. The dielectric properties of the surface layer of the gold film were estimated using the effective medium model. It made it possible to simulate changes in the surface layer of the film induced by hydrogen treatment. As a result, theoretical curves of plasmon resonance were obtained. A qualitative correlation between the experimentally observed changes and the theoretical ideas about the processes occurring during hydrogen treatment in the surface layer of the gold film on glass was achieved. [ABSTRACT FROM AUTHOR]