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A thorough theoretical study of the optical properties of periodic Si nanosphere arrays is undertaken, placing a particular emphasis on the synergy between multipolar, electric and magnetic, Mie resonances, which occur in high-refractive-index nanoparticles and can lead to a rich variety of phenomena ranging from perfect reflection to controlled diffraction. Systematic calculations using the layer-multiple-scattering method, which we properly extended to describe periodic arrays with many different scatterers per unit cell, in conjunction with finite-element simulations are presented. It is shown that rectangular arrays of pairs of Si nanospheres can efficiently diffract light in reflection or transmission mode at large angles as well as split light with minimum backreflection by properly adjusting the geometry of the structure. Our rigorous full-electrodynamic calculations highlight the importance of higher-order multipoles, which are not taken into account in the commonly employed dipole approximation, in the description of these effects. [ABSTRACT FROM AUTHOR]

Optical spectroscopy is commonly used to study the properties of 2D materials. In order to obtain the best signal-to-noise ratio, it is important to optimize the incoupling of the excitation laser and, at the same time, reduce spurious light reflection. We performed Raman spectroscopy on exfoliated hexagonal boron nitride (hBN) flakes of different thicknesses, placed on a 300 nm SiO2 on Si substrate. By changing the hBN layer thickness, we found a specific thickness, where the Raman signals from the substrate and the hBN showed maximum intensity, whereas the backscattered laser light was suppressed. To explain the increased emission, we calculated the reflectivity and transmissivity of the full layer system (air, hBN, SiO2, and Si) as a function of hBN layer thicknesses for different excitation wavelengths (457, 532, and 633 nm), using the transfer-matrix algorithm. To compare theory with the experiment, we performed Raman measurements with these three different excitation wavelengths on different flakes and determined their thicknesses with AFM measurements. The experimental results are in good agreement with the calculations, which shows the importance of thin film interference to obtain optimum spectroscopic conditions. Since interference colors are easily visible in an optical microscope, this facilitates the choice of optimum flakes for a wide range of optical characterization techniques, including Raman, photoluminescence, and single defect spectroscopy. [ABSTRACT FROM AUTHOR]

The rapid progress in deep learning technologies has accelerated the use of object detection models, but most models do not operate satisfactorily in low-light environments. As a result, many studies have been conducted on image enhancement techniques aiming to make objects more visible by increasing contrast, but the process of image enhancement may negatively impact detection as it further strengthens unwanted noises due to indirect factors of light reflection such as overall low brightness, streetlamps, and neon signboards. Therefore, in this study, we propose a technique for improving the performance of object detection in low-light environments. The proposed technique inverts a low-light image to make it similar to a hazy image and then uses a haze removal algorithm based on entropy and fidelity to increase image contrast, clarifying the boundary between the object and the background. In the next step, we used the adaptive 2D Wiener filter (A2WF) to attenuate the noise accidentally strengthened during the image enhancement process and reinforced the boundary between the object and the background to increase detection performance. The test evaluation results showed that the proposed image enhancement scheme significantly increased image perception performance with the perception-based image quality evaluator being 12.73% lower than existing image enhancement techniques. In a comparison of vehicle detection performance, the proposed technique for enhancing nighttime images combined with the detection model proved its effectiveness by increasing the average precision by up to 18.63% against existing detection methods. [ABSTRACT FROM AUTHOR]

One of the primary causes of fires at construction sites is welding sparks. Fire detection systems utilizing computer vision technology offer a unique opportunity to monitor fires in construction sites. However, little effort has been made to date in regard to real-time tracking of small sparks that can lead to major fires at construction sites. In this study, a novel method is proposed to detect welding sparks in real-time contour detection with deep learning parameter tuning. An automatic parameter tuning algorithm employing a convolutional neural network was developed to identify the optimum hue saturation value. Additional filtering methods regarding the non-welding zone and a contour area-based filter were also newly developed to enhance the accuracy of welding spark prediction. The method was evaluated using 230 welding spark images and 104 videos. The results obtained from the welding images indicate that the suggested model for detecting welding sparks achieves a precision of 74.45% and a recall of 63.50% when noise images, such as flashing and reflection light, were removed from the dataset. Furthermore, our findings demonstrate that the proposed model is effective in capturing the number of welding sparks in the video dataset, with a 95.2% accuracy in detecting the moment when the number of welding sparks reaches its peak. These results highlight the potential of automated welding spark detection to enhance fire surveillance at construction sites. [ABSTRACT FROM AUTHOR]

Event cameras are the emerging bio-mimetic sensors with microsecond-level responsiveness in recent years, also known as dynamic vision sensors. Due to the inherent sensitivity of event camera hardware to light sources and interference from various external factors, various types of noises are inevitably present in the camera's output results. This noise can degrade the camera's perception of events and the performance of algorithms for processing event streams. Moreover, since the output of event cameras is in the form of address-event representation, efficient denoising methods for traditional frame images are no longer applicable in this case. Most existing denoising methods for event cameras target background activity noise and sometimes remove real events as noise. Furthermore, these methods are ineffective in handling noise generated by high-frequency flickering light sources and changes in diffused light reflection. To address these issues, we propose an event stream denoising method based on salient region recognition in this paper. This method can effectively remove conventional background activity noise as well as irregular noise caused by diffuse reflection and flickering light source changes without significantly losing real events. Additionally, we introduce an evaluation metric that can be used to assess the noise removal efficacy and the preservation of real events for various denoising methods. [ABSTRACT FROM AUTHOR]

Learning functions defined on non‐flat domains, such as outer surfaces of non‐rigid shapes, is a central task in computer vision and geometry processing. Recent studies have explored the use of neural fields to represent functions like light reflections in volumetric domains and textures on curved surfaces by operating in the embedding space. Here, we choose a different line of thought and introduce a novel formulation of partial shape matching by learning a piecewise smooth function on a surface. Our method begins with pairing sparse landmarks defined on a full shape and its part, using feature similarity. Next, a neural representation is optimized to fit these landmarks, efficiently interpolating between the matched features that act as anchors. This process results in a function that accurately captures the partiality. Unlike previous methods, the proposed neural model of functions is intrinsically defined on the given curved surface, rather than the classical embedding Euclidean space. This representation is shown to be particularly well‐suited for representing piecewise smooth functions. We further extend the proposed framework to the more challenging part‐to‐part setting, where both shapes exhibit missing parts. Comprehensive experiments highlight that the proposed method effectively addresses partiality in shape matching and significantly outperforms leading state‐of‐the‐art methods in challenging benchmarks. Code is available at https://github.com/davidgip74/Learning-Partiality-with-Implicit-Intrinsic-Functions [ABSTRACT FROM AUTHOR]

Objective: Until now, standardized evaluation of cosmetic effects was conducted mainly in still conditions such as pictures. In real life, the consumers' experience of their cosmetics' effects is dynamic and some of the benefits can be better observed under movement. In order to capture motion‐related performance of cosmetics, we developed a video‐based paired comparison on an online platform. Methods: We validated this new tool through the evaluation of eyeshadow with high light reflection and colour gradation, especially visible under motion according to the observer point of view. This formula was compared with two marketed benchmarks. The three products were applied sequentially on the eyelid of eight Japanese women. Videos were taken in standardized light, speed and face position with a rotating camera around the face. The videos were uploaded on an online secured platform and eyelid 3D effect, highlight and colour gradation were evaluated through paired comparison test by 60 Japanese women from home on their PC or tablets. Those results were compared with picture‐based paired comparison by the same observers. Results: Video‐based paired comparison provided higher discrimination of products compared to picture‐based comparison. Conclusion: As compared to still camera acquisition, the evaluation of cosmetics based on videos is closer to real‐life experience and can bring higher discrimination, especially for motion‐related attributes. [ABSTRACT FROM AUTHOR]

We explain the anomalous outburst activity of comet 29P/Schwassmann–Wachmann 1 by the existence of satellites touching the surface of the comet nucleus at the pericenters of their orbits. It is assumed that the satellites move in eccentric orbits and a large amount of dust, the reflection of light from which causes periodic outbursts in brightness (BAA 2023), is ejected as a result of their collisions with the dust layer of the nucleus. Depending on the depth of penetration of the satellites into the dust layer, outbursts in comet brightness of various intensities occur. An improvement of the comet orbit by invoking positional observations allows the preferred direction of the ejection of material to be determined from the photocenter offset, which we interpret as the direction of the velocity vector of the largest satellite at the pericenter. The results of our numerical simulations of the ejection and subsequent motion of dust particles caused by the contact of the satellite with the dust layer of the comet nucleus explain the formation of the structures observed in the comet: the dust jets and their mirror symmetry as well as the extent of the region of material ejection from the surface of the comet nucleus. [ABSTRACT FROM AUTHOR]

This study reviews the methods of studying a microwave field power density distribution inside microwave heat treatment units and identifies shortcomings of these methods. It proposes a technique of extending the thermal-indication capabilities of standard thermal paper, according to which we provide an example of a study of temperature distribution when a three-layer thermal indicator assembly is heated in a microwave beam-type chamber of approximately 600 W. Temperature variations in the range of 25–400°C with the optical density of standard thermal paper have been experimentally studied by means of reflectance densitometry. Based on the analysis of the temperature dependence on the change in optical reflection density, six regions of the standard thermal paper conversion were identified, namely temperature ranges of 25–70°C, 70–100°C, 100–150°C, 150–210°C, 210–290°C, 290–400°C and optical densities of 0.06–0.07, 0.08–0.90, 0.91–0.99, 0.71–0.91, 0.21–0.70, and 0.20–0.38 B, respectively. In region 1, the optical density of the thermal paper does not change relative to the initial surface, and in region 2, an initial increase in the optical density is observed. In regions 3 and 4, the maximum optical density is achieved due to darkening of a leuco dye, while in region 3, there is a smooth surface of the thermal paper; in region 4, there is a velvety surface of the thermal paper due to formation of microcrystals and clots of the thermosensitive layer material. In region 5, a sharp decrease in optical density is observed as a result of discoloration of a leuco dye, and in region 6, a secondary increase in optical density is observed due to carbonization of the paper backing. The results obtained can be used to design microwave equipment as well as optimize microwave treatment conditions for materials and articles for the food, chemical, electronic, and other industries. The developed technique is also relevant for local measurements of inhomogeneity in the distribution of temperature fields when other thermometry methods cannot be used. [ABSTRACT FROM AUTHOR]

Traditional fiber scattering models, based on ray optics, are missing some important visual aspects of fiber appearance. Previous work [Xia et al. 2020] on wave scattering from ideal extrusions demonstrated that diffraction produces strong forward scattering and colorful effects that are missing from ray-based models. However, that work was unable to include some important surface characteristics such as surface roughness and tilted cuticle scales, which are known to be important for fiber appearance. In this work, we take an important step to study wave effects from rough fibers with arbitrary 3D microgeometry. While the full-wave simulation of realistic 3D fibers remains intractable, we developed a 3D wave optics simulator based on a physical optics approximation, using a GPU-based hierarchical algorithm to greatly accelerate the calculation. It simulates surface reflection and diffractive scattering, which are present in all fibers and typically dominate for darkly pigmented fibers. The simulation provides a detailed picture of first order scattering, but it is not practical to use for production rendering as this would require tabulation per fiber geometry. To practically handle geometry variations in the scene, we propose a model based on wavelet noise, capturing the important statistical features in the simulation results that are relevant for rendering. Both our simulation and practical model show similar granular patterns to those observed in optical measurement. Our compact noise model can be easily combined with existing scattering models to render hair and fur of various colors, introducing visually important colorful glints that were missing from all previous models. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

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]

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.)

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]

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]

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]

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]

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]

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]

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]

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]

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]