- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Two-parameter expansions and ray representation of the fields diffracted at thin-to-thick curved dielectric layers and conducting bodies
摘要： In this study, we introduce a uni?ed approach that allows to construct the asymptotic procedure for various high-frequency electromagnetic diffraction problems at curved dielectric, conducting, and absorbing layers, and to obtain the curvature correction to solutions. The method proposed is based on the combination of ray representations and the expansions typical for the boundary-layer technique: we seek the ?eld as a ray series, whose coef?cients are the functions of a point in space, the more “stretched” along the normal to one of the boundaries, the thicker layer is. The asymptotics are derived both in 2D and 3D formulations and are validated by comparison with analytical and numerical solutions of canonical problems.
关键词： dielectric layer,curvature,conductors,higher-order diffraction
更新于2025-09-19 17:15:36
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An Efficient Semi-Analytical Solution of a One-Dimensional Curvature Equation that Describes the Human Corneal Shape
摘要： In this paper, a numerical approach is proposed to find a semi analytical solution for a prescribed anisotropic mean curvature equation modeling the human corneal shape. The method is based on an integral operator that is constructed in terms of Green’s function coupled with the implementation of Picard’s or Mann’s fixed point iteration schemes. Using the contraction principle, it will be shown that the method is convergent for both fixed point iteration schemes. Numerical examples will be presented to demonstrate the applicability, efficiency, and high accuracy of the proposed method.
关键词： curvature equation,fixed point iteration,semi-analytical solution,Green’s function
更新于2025-09-19 17:15:36
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Gap-surface Plasmon Metasurfaces for Structured Beams Generation
摘要： The curvature effect of the 3-D layout may result in a severe deterioration of the breakdown voltage in a power lateral double-diffused MOS (LDMOS). In this paper, a novel 3-D analytical model is proposed to provide the physical insight of curvature effect in small radius region by solving the 3-D Poisson in cylindrical coordinates. The proposed model indicates that the curvature effect equivalently changes the drift region doping concentration, thus altering the surface electric field profile. The proposed 3-D model can accurately describe the surface field profile in the fingertip regions of the multifinger layout, and provides an effective way to reveal the influence of curvature effect on the performance of silicon-on-insulator LDMOS. Furthermore, based on the proposed model, a corresponding structure optimization criterion is derived to provide a simple but effective method for the device structure parameters optimization.
关键词： multifinger layout,breakdown voltage (BV),small radius region,curvature effect,3-D model
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Designing of CZTSSe Based SnS Thin Film Solar Cell for Improved Conversion Efficiency: A Simulation Study with SCAPS
摘要： This paper proposes a new computational method for retrieving shapes under unpredictable conditions such as when occlusion, geometric distortion, and differences in image resolution occur simultaneously. The human visual system retrieves shapes from incomplete information in the real world, and it has inspired a lot of computational methods of retrieving shapes. In order to retrieve shapes, the observed shapes are decided to be alike or unlike remembered shapes in memory after the comparison of these shapes. To compare the observed and remembered shapes, they must first be appropriately represented so that the points on each shape can be mapped and compared. For this reason, the shape retrieval process needs an appropriate shape representation and shape mapping methods. Moreover, the shape representations should be normalized before the mapping process. However, a normalization process for representations under unpredictable conditions has not yet been established. In this paper, we describe a shape retrieval method that enables us to retrieve shapes under unpredictable conditions with a suitable normalization process. Using curvature partition and angle-length profile, our shape retrieval method normalizes the shape representation before it does the mapping. As a result, unlike the previously proposed methods, it can be used under unpredictable conditions such as when occlusion, geometric distortion, and differences in image resolution occur simultaneously.
关键词： curvature partition,Shape recognition,geometric parameter,occlusion,shape retrieval
更新于2025-09-19 17:13:59
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Enhanced light-emitting diode induced fluorescence detection system with capillary electrophoresis
摘要： An enhanced fluorescence detection system of capillary electrophoresis (CE) was equipped with a concave silver mirror, by which the detection sensitivity of light-emitting diode induced fluorescence (LEDIF) can be increased greatly. The silver concave mirror and the cathode window in photomultiplier tube (PMT) were accurately set face to face at the same axis. When the two labeled tumor markers exactly moved to the center of detection window, the emission from analytes are excitated by LED source. Currently, the analytes may be regarded as a luminescent source point. When the source point exactly moves to the focus of the concave mirror, the emission of the labeled sample was collected effectively, enhanced by convergence and reflected by the concave mirror. Then it was sensitively detected by the PMT. The optical mechanism of enhancing detection sensitivity was explored. A simple comparative test on sensitivity was carried out, which aimed to compare sensitivity of the new detection system with concave mirror to that without concave mirror but the other conditions were kept the same. Two tumor markers labeled with FITC were selected for the test, using the simple LEDIF detect system. The results (LOD, 150 nM for L-Leu and L-Val) showed that the detection sensitivity matched with concave mirror reached more 16 times than the detection method without concave mirror.
关键词： Curvature radius,Light-emitting diode induced fluorescence,Tumor markers,Concave silver mirror,Polarized light,Highly sensitive optical detector
更新于2025-09-19 17:13:59
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Gate controlled valley polarizer in bilayer graphene
摘要： Sign reversal of Berry curvature across two oppositely gated regions in bilayer graphene can give rise to counter-propagating 1D channels with opposite valley indices. Considering spin and sub-lattice degeneracy, there are four quantized conduction channels in each direction. Previous experimental work on gate-controlled valley polarizer achieved good contrast only in the presence of an external magnetic field. Yet, with increasing magnetic field the ungated regions of bilayer graphene will transit into the quantum Hall regime, limiting the applications of valley-polarized electrons. Here we present improved performance of a gate-controlled valley polarizer through optimized device geometry and stacking method. Electrical measurements show up to two orders of magnitude difference in conductance between the valley-polarized state and gapped states. The valley-polarized state displays conductance of nearly 4e2/h and produces contrast in a subsequent valley analyzer configuration. These results pave the way to further experiments on valley-polarized electrons in zero magnetic field.
关键词： valley polarizer,quantized conduction channels,gate-controlled,Berry curvature,bilayer graphene
更新于2025-09-19 17:13:59
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Polymer Optical Fiber Sensor System for Multi Plane Bending Angle Assessment
摘要： In this paper, a polymer optical fiber (POF) sensor system for angle estimation in multi-planar movements is proposed. The sensor system comprises of three intensity variation-based POF sensor multiplexed via a time multiplexing technique with the side-coupling of the light sources. A theoretical analysis is performed for the sensor system as well as a numerical analysis using the finite element method (FEM) in order to investigate the cross-sensitivity for multi planar movement and the effect of the sensors positioning on the sensor sensitivity due to the stress distribution on the fiber. Such analyses indicate the possibility of not only increasing the sensor accuracy on single plane angle estimation by combining the responses of two sensors, but also the possibility of obtaining an angle estimation combining the sensor responses for multi plane movements. Then, an experimental analysis is performed on the sensor system, which corroborates the numerical and analytical responses and enable a threefold error reduction when two sensors are used on the single plane estimation instead of one. In addition, errors as low as 1.15% in the best case and 4.30% in the worst case were obtained on the tests with multi plane movement. The results obtained in this paper indicate the possibility of using this sensor system on the shape reconstruction applications in structural health monitoring, robotics and movement analysis.
关键词： Optical fiber sensors,Euler angles,Polymer optical fiber,Curvature sensors
更新于2025-09-12 10:27:22
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A double raster laser scanning strategy for rapid die-less bending of 3D shape
摘要： Double raster scanning approach to 3D laser forming was investigated to obtain a large deformation with one-step laser irradiation, avoiding repetitive scanning. The magnitude of the deformation during raster scanning was found to be strongly dependent on the overlapping between adjacent passes, which can be controlled by changing their spacing and the beam diameter. Therefore, 3D deformation during raster scanning has been analyzed at various overlap ratios, whose effect on the temperature and strain distribution were discussed. As the heat transfer mode significantly influences the uniformity of the bending process, the variations in bending angles with negative and positive overlapping ratios have also been investigated. The ratio of the longitudinal and lateral curvatures decreased with the increasing overlap ratio. Therefore, the effect of the lateral side is more important for specifying the final symmetry of the part, playing a critical role in bending with higher overlap ratios. In a rectangular part, deformation of the lateral side was found to be more difficult, showing strong dependence on the length of the scanning track, compared with the space of the adjacent passes. Through process characterization, the double raster scanning process has been well understood and proved to be a feasible approach to 3D laser forming of rectangular parts.
关键词： Curvature,Overlap,Laser bending,Heat transfer,Laser forming,Raster scanning
更新于2025-09-12 10:27:22
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Growth mechanism of gold nanorods: the effect of tip-surface curvature as revealed by molecular dynamics simulations
摘要： To understand the anisotropic growth mechanism of gold nanorods (AuNRs) during colloidal synthesis is critical for controlling the nanocrystal size and shape and thus has implications in tuning the properties for applications in a wide range of research and technology fields. In order to investigate the role of the cetyltrimethylammonium bromide (CTAB) coating in the anisotropic growth mechanism of AuNRs, we used molecular dynamics (MD) simulations and built a computational model that considered explicitly the effect of the curvature of the gold surface on CTAB adsorption and therefore differentiated the CTAB arrangements on flat and curved surfaces, representing the lateral and tip facets of growing AuNRs, respectively. We verified that on a curved surface, a lower CTAB coverage density and larger intermicellar channels are generated compared to those on a flat surface. Using umbrella sampling simulations, we measured the free energy profile and verified that the environment around a curved surface corresponds to an easier migration from the solution to the gold surface for the [AuBr2]? species than does a flat surface. Long unbiased molecular dynamics simulations also corroborated the umbrella sampling results. Therefore, the [AuBr2]? diffusion through the environment of the tips is much more favorable than in the case of lateral facets. This shows that the surface curvature is an essential component of the anisotropic growth mechanism.
关键词： molecular dynamics,growth mechanism,CTAB,umbrella sampling,surface curvature,gold nanorod synthesis
更新于2025-09-12 10:27:22
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Measurement of electron beam moire fringes with pulsed-dilation framing camera using different lasers
摘要： The electron beam moire fringe (EBMF) is generated by using a pulse-dilation framing camera. Its characteristics are measured via a nanosecond- and a femtosecond-laser. The wavefront curvature radius of the two lasers is calculated based on the measurement of the EMBF rotation angle and this result is discussed in detail. The experiments show that the EBMF rotation angles measure 31.9° and 16.6°, while the wavefront curvature radii are 12.5 mm and 21.1 mm, when the ns-laser and the fs-laser are used, respectively. This study greatly contributes in the development of EBMF-based technologies and proposes novel application directions for the use of pulse-dilation framing cameras.
关键词： Electron beam moire fringe,Ultrafast diagnostic techniques,Wavefront curvature radius,Pulse-Dilation framing camera
更新于2025-09-12 10:27:22