Mirror Reflection Research Articles

Broadband spectral analysis of chiral nanophotonic structures at circularly polarized incidence using DGTD solver

Abstract A transient circularly polarized excitation and its implementation in a generalized dispersive material model based discontinuous Galerkin time-domain solver are proposed for spectral analysis of chiral nanophotonic structures. The expression of a circularly polarized pulse with a certain bandwidth, which is real-valued and enables multi-physics and nonlinearity, is derived comprehensively. Numerical examples of nanophotonic structures are given in this paper. Such as reflection from metallic mirrors, transmission from S-shaped dielectric metasurfaces, and the spin response of C4 symmetrically arranged right-handed enantiomers. These examples demonstrate the accuracy and capability of the proposed method.

Level splitting induced by collective interaction in a waveguide QED system

In waveguide quantum electrodynamics (QED) systems, noninteracting quantum entities can be coupled through the vacuum field of the waveguide, leading to both coherent and dissipative interactions. We systematically demonstrate that the reflection spectrum is clear and direct in representing the collective interaction using the mirror reflection properties of semi-infinite waveguides. Due to the destructive interference with its mirror image, the emitter is decoupled from the waveguide, suppressing the decay so that the reflection spectrum shows an anticrossing phenomenon induced by coherent interaction. Moreover, the reflection spectrum of an anti-parity-time symmetric Hamiltonian caused by dissipative coupling exhibits an unconventional splitting characterized by level attraction transitioning at exceptional points. Our findings highlight the significance of exploring non-Hermitian effects in waveguide quantum systems, offering potential applications in quantum networks reliant on long-distance interactions. Published by the American Physical Society 2024

A theoretical study of the output coupler reflectivity effect on the characteristics of Er+3 laser pulse at passively q-switching

The objective of this study deal the effect of the output coupler mirror reflectivity of laser system on behavior and characteristics (duration and energy) of erbium passive Q-switching laser pulse was studied theoretically. In the methods of the study, virtual passive Q-switching laser system consist of major elements such as erbium doped silica as an active medium, Cr+4: YAG crystal used as a saturable absorber, and the mirrors of resonator. Mathematical rate equations model has been used to describe the physical relationship between this element has been solved numerically by Rung - Kutta –Fehlberg method. The results showed regarding the pulse behavior, the increasing value of output coupler mirror reflectivity lead to decreasing of rising and falling time of pulse, so the emission of pulse occur in an advanced time. While regarding the pulse characteristics, the pulse was distinguishable by short duration and high energy, resulting high power of pulse when the output coupler mirror reflectivity increasing. Regarding of results discussion, the study attributes the results to a decrease of the initial and final population inversion density of active medium that results from the increasing value of output coupler mirror reflectivity. Therefore, it is possible to conclude in order to improve the characteristics of erbium passive Q-switching laser pulse; it is appropriate increase the value of output coupler mirror reflectivity within acceptable limits.

Heliostat Field Optical Efficiency Calculation

Abstract The solar power tower technology has the advantages of green pollution-free and stable power generation, which has gradually attracted extensive attention from researchers in recent years. The quick computation of the solar heliostat field’s optical efficiency carries substantial potential for refining the design of the heliostat field, thereby enhancing the efficiency of power generation. Based on the parallel light hypothesis, we propose a fast algorithm designed to compute the optical efficiency of heliostat field. The algorithm takes into account various optical loss terms such as mirror reflectivity, cosine efficiency, shadowing and blocking efficiency, atmospheric transmittance efficiency and truncation efficiency. When calculating the shadowing and blocking efficiency, the “judgment rectangle” is used to quickly screen the candidate heliostat that may produce shadowing and blocking to the target heliostat. When calculating the truncation efficiency of the receiver surface, the strip discrete method and geometric projection method are used to quickly judge whether the reflected light is intercepted by the receiver, thus improving the calculation speed of optical efficiency. Consider a surrounding heliostat field as a test case, the proposed algorithm is compared with the conventional ray tracing, and the effectiveness and efficiency of the new algorithm are verified. The algorithm proposed in this paper has the advantages of accurate results and high calculation efficiency, and provides valuable insights that can be utilized for optimizing the design of heliostat field and improving the efficiency of tower solar thermal power generation.

The impact of camera-monitor system viewing angles on drivers’ distance perception: A simulated driving study

Camera-monitor systems (CMS) are increasingly used in driving. CMS separates the driver's sight line from the camera view, due to the lack of mirror reflection, only changing the camera's visual axis angle may affect the driver's rear view perception. While previous research has explored camera height and field of view, the effects of horizontal and vertical viewing angles alone remain unclear. This study aimed to evaluate how the horizontal viewing angle and vertical viewing angle of CMS camera affect distance estimation and car-following tasks. By changing the horizontal and vertical viewing angle, different self-vehicle references and horizon positions were formed in the image. Two experiments were conducted with the CMS around the steering wheel (Experiment 1) and at the bottom of the A-pillar (Experiment 2). Independent variables were the horizontal viewing angle (reference scale: 1/4, 1/3, 1/2) and vertical viewing angle (horizon position: 1/2, 1/3). Dependent variables included distance estimation error ratio and following distance. Experiment 1 demonstrated a significant interaction effect: a smaller reference scale and higher horizon position reduced distance underestimation. Additionally, a smaller reference scale for the participants' self-vehicle resulted in shorter following distances. In Experiment 2, the distance estimation outcomes on the left display aligned with those of Experiment 1; however, the influence of the viewing angle was diminished on the right display. The study suggests CMS design should balance vehicle reference inclusion with environmental cues, enhancing distance perception and driving safety. The consistency between CMS design and driver familiarity also needs to be considered.

Efficient Fault Warning Model Using Improved Red Deer Algorithm and Attention-Enhanced Bidirectional Long Short-Term Memory Network

The rapid advancement of industrial processes makes ensuring the stability of industrial equipment a critical factor in improving production efficiency and safeguarding operational safety. Fault warning systems, as a key technological means to enhance equipment stability, are increasingly gaining attention across industries. However, as equipment structures and functions become increasingly complex, traditional fault warning methods face challenges such as limited prediction accuracy and difficulties in meeting real-time requirements. To address these challenges, this paper proposes an innovative hybrid fault warning method. The proposed approach integrates a multi-strategy improved red deer optimization algorithm (MIRDA), attention mechanism, and bidirectional long short-term memory network (BiLSTM). Firstly, the red deer optimization algorithm (RDA) is enhanced through improvements in population initialization strategy, adaptive optimal guidance strategy, chaos regulation factor, and double-sided mirror reflection theory, thereby enhancing its optimization performance. Subsequently, the MIRDA is employed to optimize the hyperparameters of the BiLSTM model incorporating an attention mechanism. A predictive model is then constructed based on the optimized Attention-BiLSTM, which, combined with a sliding window approach, provides robust support for fault threshold identification. The proposed algorithm’s efficacy is demonstrated through its application to real-world gas-fired power plant equipment fault cases. Comparative analyses with other advanced algorithms reveal its superior robustness and accuracy in efficiently issuing fault warnings. This research not only provides a more reliable safeguard for the stable operation of industrial equipment but also pioneers a new avenue for the application of metaheuristic algorithms.

Fabrication of optimized partial-reflection coatings for mid-infrared quantum cascade lasers

This study presents both numerical modeling and experimental fabrication of three different partial-reflection (PR) coatings each optimized for quantum cascade lasers (QCLs) that emit radiation in the mid-infrared range. A novel double-layer PR coating comprising silicon dioxide (SiO2) and silicon nitride (Si3N4) was proposed as a potential solution for compatibility with QCLs fabrication processes. Subsequently, the PR coating was compared with two well-known PR coatings: a single layer of aluminum oxide (Al2O3) and a single layer of yttrium oxide (Y2O3). The coatings were designed to reduce the reflectivity of the front laser mirror from 30% to approximately 13%. The thickness of the dielectric layers was optimized for lasers emitting at 4.4 μm, with applicability in the 2.5–6 μm range. The proposed double-layer coating achieved the desired reflectivity while reducing the total coating thickness by 120 nm. By using the presented coatings it will be possible to increase the optical power of Mid-Infrared QCLs.

Research on mid-infrared quantum cascade lasers spectral beam combining

Quantum cascade lasers (QCLs) in the mid-infrared (MIR) hold significant potential for widespread applications in both military and civilian contexts. However, the utility of present single-chip QCLs is hampered by issues such as low output power and subpar beam quality. This study addresses these limitations by employing spectral beam combining (SBC) based on a diffraction grating, with an aim to enhance both power and beam quality of MIR QCLs. Coaxial power synthesis of three single-chip QCLs (around 4.75 μm) is achieved experimentally, importantly, the beam quality did not decrease after combining, essentially maintaining the same quality as before combining. It is proposed that there are four main factors affecting the combining efficiency, namely operating optical power (or driving current) of the chips, individual differences in QCL chips, diffraction grating, and reflectivity of feedback mirror, and their effects on the combining efficiency are discussed separately. This study confirms that SBC is an effective way to obtain high-power and high-beam quality MIR QCL sources, and lays a research foundation for more beam spectral combining.

On-Line Measurement of Tracking Poses of Heliostats in Concentrated Solar Power Plants.

The tracking pose of heliostats directly affects the stability and working efficiency of concentrated solar power (CSP) plants. Due to occlusion, over-exposure, and uneven illumination caused by mirror reflection, traditional image processing algorithms showed poor performances on the detection and segmentation of heliostats, which impede vision-based 3D measurement of tracking poses of heliostats. To tackle this issue, object detection using deep learning neural networks are exploited. An improved neural network based on YOLO-v5 framework has been designed to solve the on-line detection problem of heliostats. The model achieves a recognition accuracy of 99.7% for the test set, outperforming traditional methods significantly. Based on segmented results, the corner points of each heliostat are found out using Hough Transform and line intersection methods. The 3D poses of each heliostat are then solved out based on the image coordinates of specific feature points and the camera model. Experimental and field test results demonstrate the feasibility of this hybrid approach, which provides a low-cost solution for the monitoring and measurement of tracking poses of the heliostats in CSP.

Calculation of the Critical Liquid Production of Cyclic Steam Stimulation in Heavy Oil Reservoir with Edge Water

Abstract For heavy oil reservoirs with edge water, when the liquid production of cyclic steam stimulation is excessively high, there is a risk of edge-water invasion. Therefore, the liquid production of cyclic steam stimulation is of great significance to the prevention of edge-water invasion in heavy oil reservoir with edge water. Currently, many studies on the critical liquid production in oil reservoir by water flooding are conducted. However, there is few research on the critical liquid production in heavy oil reservoir by cyclic steam stimulation. To fill this gap, The formation after cyclic steam stimulation is divided into the heated zone and the unheated zone. A characterization method for the flow field parameters after cyclic steam stimulation is established. By transforming the length of the thermal swept zone, the comprehensive mobility of the heated zone is equivalently represented as the comprehensive mobility of the unheated zone. On this basis, considering the threshold pressure gradient in heavy oil, a calculation method for the critical liquid production after cyclic steam stimulation in oil reservoir is developed based on the theory of mirror reflection and the superposition of potentials. The results show: (1) Permeability being constant, the critical liquid production rate increases with the increase in cyclic steam injection quality. With a constant cyclic steam injection quality, the critical liquid production rate increases with the increase in permeability; (2) Guided by the established relationship curve diagram between critical liquid production and crude oil mobility, the development plan is designed. As a result, the comprehensive water cut in the oilfield is 8.1%, and no water invasion has occurred; (3) Guided by the established relationship curve diagram between the cumulative liquid production and cumulative heat injection corresponding to different critical liquid production rates, adjustments were made to the oilfield development plan. As a result, the critical liquid production rate for well A1 increased from 110 t/d in the first cycle to 150 t/d in the second cycle.

On the electromagnetic wave interaction with subluminal, luminal, and superluminal mirrors

As predicted by A. Einstein [Ann. Phys. (Leipzig) 17, 891 (1905)], the electromagnetic wave reflected at a moving mirror is frequency-upshifted and intensified as high as the mirror velocity is close to the speed of light in vacuum. However, at this limit the mirror reflectivity vanishes, because the higher the wave frequency the more transparent matter is. To resolve this paradox, we analyse the electromagnetic wave propagation in medium where the refractive index modulation moves at the speed of light in vacuum. Although the luminal and superluminal modulations are unconditionally transparent for the incident radiation, they both can reflect. We find the new type of the electromagnetic wave reflection with the increasing in time frequency inside the luminal mirror. If the modulation disappears the high frequency radiation is released as a short wavepacket.

Testing the optical components for the National Ignition Facility time-resolved soft x-ray opacity spectrometer (OpSpecTR).

Opacity measurements are being carried out at the Z-facility at Sandia National Laboratories and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. The current soft x-ray Opacity Spectrometer (OpSpec) used on the NIF uses two elliptically bent crystals in time-integrated mode on either an image plate or a film. Plans are under way to expand these opacity measurements into a mode of time-resolved detection, called OpSpecTR. Previously, considerations for the available hCMOS detector size and photometrics led to a crystal geometry redesign and the use of a grazing angle x-ray mirror. The mirror acts as a low-pass x-ray energy filter, reducing the contribution of higher energy x rays. The first tests of the mirror and the crystal for OpSpecTR are presented here. The size of the mirror reflection and the reflectivity is tested using a Manson x-ray source. The mirror coupled with the new elliptical crystal shape demonstrates OpSpecTR's spectral coverage. The results from the x-ray optics performance testing are shown along with the intended design.

An efficient improved parrot optimizer for bladder cancer classification

Bladder Cancer (BC) is a common disease that comes with a high risk of morbidity, death, and expense. Primary risk factors for BC include exposure to carcinogens in the workplace or the environment, particularly tobacco. There are several difficulties, such as the requirement for a qualified expert in BC classification. The Parrot Optimizer (PO), is an optimization method inspired by key behaviors observed in trained Pyrrhura Molinae parrots, but the PO algorithm becomes stuck in sub-regions, has less accuracy, and a high error rate. So, an Improved variant of the PO (IPO) algorithm was developed using a combination of two strategies: (1) Mirror Reflection Learning (MRL) and (2) Bernoulli Maps (BMs). Both strategies improve optimization performance by avoiding local optimums and striking a compromise between convergence speed and solution diversity. The performance of the proposed IPO is evaluated against eight other competitor algorithms in terms of statistical convergence and other metrics according to Friedman’s test and Bonferroni–Dunn test on the IEEE Congress on Evolutionary Computation conducted in 2022 (CEC 2022) test suite functions and nine BC datasets from official repositories. The IPO algorithm ranked number one in best fitness and is more optimal than the other eight MH algorithms for CEC 2022 functions. The proposed IPO algorithm was integrated with the Support Vector Machine (SVM) classifier termed (IPO-SVM) approach for bladder cancer classification purposes. Nine BC datasets were then used to confirm the effectiveness of the proposed IPO algorithm. The experiments show that the IPO-SVM approach outperforms eight recently proposed MH algorithms. Using the nine BC datasets, IPO-SVM achieved an Accuracy (ACC) of 84.11%, Sensitivity (SE) of 98.10%, Precision (PPV) of 95.59%, Specificity (SP) of 95.98%, and F-score (F1) of 94.15%. This demonstrates how the proposed IPO approach can help to classify BCs effectively. The open-source codes are available at https://www.mathworks.com/matlabcentral/fileexchange/169846-an-efficient-improved-parrot-optimizer.

Geometry of plastic deformation in metals as piecewise isometric transformations

Deformation mechanisms of crystalline solids has been the subject of research for more than two centuries. The theory of dislocations dominates modern views but still has significant gaps demanding the introduction of additional concepts for the coherent quantitative description of physical phenomena. In this work, we propose a coherent geometric description of motion and deformation in crystalline solids as piecewise isometric transformations (PWIT). The latter only includes operations that, similar to interatomic spacing in crystalline lattice, do not alter distances between reference points, i.e. translations, rotations and mirror reflections. The difference between solid-body translations and plastic deformations is that the isometric transformations have discontinuities that in real-life materials realise through dislocations (termination of shifts), disclinations (termination of rotations), and twins (mirror reflections). The conceptual description of plastic deformations as PWIT can be useful for the better description of physical phenomena, proposing new hypothesis, and for developing predictive analytical models. In this paper, the use of this conceptual description enables proposing new hypothesis about the nature of such interesting phenomena in severe plastic deformation as (i) stationary ‘solid state turbulence’ stage in high pressure torsion, and (ii) rate of mass transfer (mechanically assisted diffusion) in simple-shear deformation.

Reflectivity measurement of a silicon carbide mirror sample for ITER divertor vacuum ultraviolet spectrometer.

The first mirror is the front-end optic component that reflects light emitted from the plasma to the diagnostic system in fusion plasmas. Silicon carbide (SiC), known for its relatively high mechanical strength and radiation tolerance, has been selected as the substrate material for the first mirror in the ITER divertor vacuum ultraviolet (VUV) spectrometer. To measure the reflectivity of the ellipse cylindrical SiC mirror to be manufactured, a device for reflectivity measurement in the VUV wavelength range was developed. First, the reflectivity of a sample SiC mirror (15mm diameter × 10mm thick) was measured across the ITER-required incidence angles, and the results are reported in this study. A hollow cathode lamp with helium gas was used as the VUV light source in the wavelength range of 23-60nm, and a dedicated VUV spectrometer to select specific wavelengths was developed. The spectrometer utilized laminar-type replica diffraction gratings (Shimadzu 30-006) and two back-illuminated charge-coupled devices (BI-CCD, Andor DO 940P-BEN) for the grating and detector, respectively. A cropping technique with aperture was employed to precisely localize the VUV light's reflection onto the SiC mirror surface. The experimentally measured reflectivity values of SiC at the required incidence angles of VUV light were compared with theoretically calculated reflectivity curves. The oxidation layer (SiO2) formed on the SiC surface and the incidence angle of VUV light to the BI-CCD chip (E2V) would be the factors affecting the accuracy of the reflectivity.

The concept of “spectacularity” in the context of cultural concepts

In our imagination the concept of “spectacularity” is associated with images of a fair, a bright, exciting, cheerful carnival with laughter, joy, bright colors, and mirror refl ections. Certainly, “spectacularity” is not only about positive impressions: it can also be shocking or frightening, as evidenced by the Latin word “specter” (from the Latin “spectrum” — “vision”), meaning “apparition”, “ghost”, which again is one of the synonyms of Russian “spectacularity”. The phenomena of spectacle and spectacularity can be considered as phenomena of society and culture. The article shows approaches to the analysis of the concept of “spectacularity”, which are presented in the cultural and philosophical works of Russian and foreign scientists: M.M. Bakhtin, J. Ortega y Gasset, A.I. Mazaev, N.A. Khrenov, E.V. Salnikova and others. It is revealed that in developing these concepts, the authors rely on an analysis of traditions and rituals associated with festive culture. Often, through the holiday/ mundanity dichotomy, the authors identify the essential characteristics of concepts. Elite and profane, “low” and “high” — these are the characteristics that are used when talking about mass and elite culture. The materials of the article can be used within the disciplines “History of Culture”, “History of Art” and “Aesthetics”

Thermodynamic performance evaluation and optimization of a hybrid system integrating vacuum graphene-anode thermionic converters with direct carbon fuel cells

An efficient hybrid system integrating a direct carbon fuel cell (DCFC) with a vacuum graphene-anode thermionic converter (VGTC) is proposed for cogeneration. The VGTC efficiently recycles waste heat released from the DCFC and generate additional electricity, significantly improving energy utilization efficiency and economic performance. A comprehensive mathematical model is developed to quantitatively assess the thermodynamic performance of the hybrid system, taking into account the overpotential losses of the DCFC and the irreversible energy losses occurring within the system. The results show that at an operating temperature of 923 K, the hybrid system can achieve a maximum power density of 466 W/m2, which is approximately 1.34 times that of a single DCFC, indicating a significant improvement in output performance. Besides, the optimal operating region and parameter selection criteria for the hybrid system are determined using finite-time thermodynamic optimization theory. Furthermore, the effects of essential parameters on the output performance of the hybrid system, such as the operating temperature of the DCFC, the heat transfer coefficient, the Fermi level of graphene, the work function of the cathode, the thermal emissivity, and the reflectivity of the back mirror, are investigated. Finally, the comparative study shows that the proposed hybrid system outperforms other previously reported hybrid systems regarding output electric power and conversion efficiency due to the efficient high-grade waste heat recovery and energy conversion by the VGTC.

Dual First and Second Surface Solar Mirrors of Polished WS2 and Silver by Dynamical Chemical Plating Technique on Polycarbonate.

This work proposes for the first time protecting-reflecting on both sides of plated mirrors and a solution to polycarbonate surface vulnerability to weathering and scratching using tungsten disulfide (WS2) by mechanical polishing. The ability of the dynamic chemical plating (DCP) technique to deposit Ag films at the nanometer scale on a polycarbonate (PC) substrate and its characteristics to be metallized is also shown. These deposits hold significant promise for concentrated solar power (CSP) applications. Complementarily, the application of WS2 as a reflective film for CSP by mechanical polishing on smooth polycarbonate surfaces is both novel and practical. This technique is innovative and scalable without needing reactants or electrical potential, making it highly applicable in real-world scenarios, including, potentially, on-site maintenance. The effects of surface morphology and adhesion, and the reflectivity parameters of the silver metallic surfaces were investigated. Wettability was investigated because it is important for polymeric surfaces in the activation and metal deposition immediately after redox reactions. The flame technique improved wettability by modifying the surface with carbonyl and carboxyl functional groups, with PC among the few industrial polymers that resisted such a part of the process. The change in the chemical composition, roughness, and wettability of the surfaces effectively improved the adhesion between the Ag film and the PC substrate. However, it did not significantly affect the adhesion between PC and WS2 and showed its possible implementation as a first surface mirror. Overall, this work provides a scalable, innovative method for improving the durability and reflectivity of polycarbonate-based mirrors, with significant implications for CSP applications.

Ghost crab (Ocypode quadrata) modify their behavior during mirror exposure

Recently, ghost crabs (Ocypode quadrata) were shown to exhibit behavior consistent with passing the mark test, which implies the capacity for self-recognition. Considering this, it seems reasonable to suggest these animals can also distinguish their mirror image from different social stimuli, such as live conspecifics. In the current research, ghost crabs were placed in an experimental tank bisected by a mirror, clear partition separating a conspecific, and non-reflective partition on separate trials. Aggressive threat displays, time spent near partitions, eye cleaning, and partition contact were recorded during each condition. Results showed more aggression in trials with a conspecific present (i.e. clear partition), though this effect was only marginally significant. In addition, eye cleaning was significantly lower in the clear, compared to mirror and non-reflective treatments. Significantly more contact occurred with non-reflective partitions and time near each barrier was similar. These findings might suggest the capacity to distinguish mirror reflections from conspecifics, and mirror self-recognition could promote such ability. This, and other alternatives, are discussed as potential explanations for the observed effects.

Robot-assisted system for non-invasive wide-range flexible eye positioning and tracking in particle radiotherapy.

Particle (proton, carbon ion, or others) radiotherapy for ocular tumors is highly dependent on precise dose distribution, and any misalignment can result in severe complications. The proposed eye positioning and tracking system (EPTS) was designed to non-invasively position eyeballs and is reproducible enough to ensure accurate dose distribution by guiding gaze direction and tracking eye motion. Eye positioning was performed by guiding the gaze direction with separately controlled light sources. Eye tracking was performed by a robotic arm with cameras and a mirror. The cameras attached to its end received images through mirror reflection. To maintain a light weight, certain materials, such as carbon fiber, were utilized where possible. The robotic arm was controlled by a robot operating system. The robotic arm, turntables, and light source were actively and remotely controlled in real time. The videos captured by the cameras could be annotated, saved, and loaded into software. The available range of gaze guidance is 360° (azimuth). Weighing a total of 18.55kg, the EPTS could be installed or uninstalled in 10s. The structure, motion, and electromagnetic compatibility were verified via experiments. The EPTS shows some potential due to its non-invasive wide-range flexible eye positioning and tracking, light weight, non-collision with other equipment, and compatibility with CT imaging and dose delivery. The EPTS can also be remotely controlled in real time and offers sufficient reproducibility. This system is expected to have a positive impact on ocular particle radiotherapy.