- 标题
- 摘要
- 关键词
- 实验方案
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Li-Tect: 3D Monitoring and Shape Detection using Visible Light Sensors
摘要： In this paper, we propose Li-Tect, an algorithm to detect the shape of an object located in an indoor environment using low cost optical elements through sensing the environment's light. The algorithm analyzes, relying on the predictability of optical propagation paths, how much light is expected to propagate in the absence of obstructions caused by the presence of an object. Then, based on the received light when the object is in the room, the algorithm infers the shape of the object. In addition, the algorithm considers the reflected paths from surfaces in order to determine the object's estimated shape. We study five different scenarios characterized by different levels of complexity, room sizes and a range of reflection nodes. The algorithm is also tested in a real prototype where several experiments are carried out in two scenarios to demonstrate the capabilities of Li-Tect in two and three dimensional monitoring and shape detection cases. Finally, the results show that the shape and the detection of objects in the scenarios can be easily acquired with high accuracy, even if the number of transceivers is reduced.
关键词： Visible Light Sensors,Ray Tracing,Monitoring,Visible Light Communications,Shape Detection
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Electron Ray Tracing in a Cylindrical Defector Analyzer for Field Emission Spectroscopy
摘要： Field-emission spectroscopy (FES) is a technique that acquires an energy spectrum of the electrons emitted from a field emitter. A cylindrical deflector analyzer (CDA) is often used for FES. Assuming that the electric field in the CDA is an ideal cylindrical field, it is known that the optimum deflection angle is 127°. In fact, there is a deviation from an ideal cylindrical field in the CDA. In particular, a fringing field occurring at the vicinity of entrance and exit of slits is not negligible. Therefore, herein, we performed three-dimensional (3D) electric field calculations and ray tracing using a 3D boundary charge method (BCM) that we developed previously. Using this approach, the CDA can be optimized to improve the energy resolution of FES.
关键词： field emission spectroscopy,cylindrical deflection angle,electron ray tracing,optimum deflector angle,three-dimensional boundary charge method
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Lighting Design Using Ray Tracing
摘要： This article describes lighting system design using ray tracing. This method can be applied in cases where calculation includes non-diffuse reflective materials, light sources have dimensions comparable to distances from reflective materials and also in case where diffused reflective surfaces influence each other in terms of distribution of light.
关键词： illumination,luminaire,ray tracing,lighting system design
更新于2025-09-23 15:21:21
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An optimized space-time Gaussian beam migration method with dynamic parameter control
摘要： In the Gaussian beam (GB) method, initial beam parameters are principal factors influencing the accuracy and computational efficiency of seismic depth imaging. Various optimized beam parameter strategies for Gaussian beam migration (GBM) have been proposed to improve imaging quality as well as computational efficiency, while optimized space-time Gaussian beam schemes for seismic migration have still not been fully investigated. In this paper, an optimized space-time Gaussian beam approach with dynamic parameter control for seismic depth imaging is developed. We first provide an expression for dynamic beam parameter by taking in account the effect of velocity field variation on the beam forming. Based on dynamic beam parameters, the new space-time adaptive Gaussian beam generated by an arbitrary source wavelet is obtained, which can adaptively calculate the beam width to make the seismic beam energy better focused in the central ray neighborhood. Then, the forward wavefield is constructed in two-dimensional (2D) acoustic media by space-time adaptive Gaussian beam for the implementation of migration. Adhering to the framework of conventional space-time Gaussian beam method, we perform the up-going ray tracing from subsurface imaging points to the receiver surface to compute the asymptotic Green function for the construction of the backward wavefield. Numerical experiments demonstrate that the new presented approach has a superior accuracy for seismic depth imaging in both shallow and deep regions compared to the conventional space-time Gaussian beam migration scheme.
关键词： Space-time Gaussian beam,Green function,Up-going ray tracing,Dynamic beam parameter
更新于2025-09-23 15:21:21
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A Combined Ray Tracing Method for Improving the Precision of the USBL Positioning System in Smart Ocean
摘要： The ultra-short baseline positioning system (USBL) has the advantages of flexible application and easy installation, and it plays an extremely important role in the underwater positioning and communication. The error of the USBL in underwater positioning is mainly caused by a ranging error due to ray tracing, a phase difference error of the USBL, and acoustic noise in the underwater communication. Most of these errors are related to the changes in the sound speed during its propagation through the ocean. Therefore, when using the USBL for underwater detection, it is necessary to correct the sound speed profile in the detection area and optimize the ray tracing. Taking into account the actual conditions, this paper aims at correcting the model of underwater sound speed propagation and improving the tracking method of sound lines when the marine environment in the shallow sea area changes. This paper proposes a combined ray tracing method that can adaptively determine whether to use the constant sound speed ray tracing method or the equal gradient ray tracing method. The theoretical analysis and simulation results show that the proposed method can effectively reduce the error of slant distance in USBL compared with the traditional acoustic tracking method and the constant sound speed ray tracing method. The proposed sound ray correction algorithm solves the contradiction between the number of iterations and the reduction of positioning error and has engineering application value.
关键词： acoustic positioning,constant sound speed ray tracing,ultra-short baseline (USBL),equal gradient ray tracing,sound speed profile
更新于2025-09-23 15:21:01
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Dependence of macro-bending loss on bending configuration of multimode optical fibers studied by ray-tracing simulation
摘要： The macro-bending loss of multimode step-index helical, s-shaped, and figure-of-eight-shaped optical fibers is investigated by ray-tracing simulation. In particular, fibers with the same radius of curvature having the three different configurations are compared. It is found that macro-bending loss strongly depends on the configuration as well as the bending curvature of the fibers. For the same curvature, the macro-bending loss of fibers in different configurations differs markedly. Thus, when comparing or reporting the macro-bending loss of multimode optical fibers, it is necessary to specify the bending radius as well as the fiber configuration.
关键词： Ray-tracing simulation,Macro-bending loss,Optical fiber
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Multipath Propagation Analysis of 5G Systems at Higher Frequencies in Courtyard (Small Cell) Environment
摘要： The main target of this paper is to study the propagation characteristics of an outdoor and indoor user utilizing 5G system at higher frequency in a courtyard surrounded by building walls i.e. small cell environment. This research work is carried out by doing 3D ray tracing simulations utilizing “sAGA” – a 3D ray tracing tool. Unlike the conventional cellular network frequencies, the considered frequencies in the scope of this work are 15 GHz, 28 GHz and 60 GHz. For simulation routes, the results are provided in the form of received signal strength. For static points, the results are presented in the form of power angular spectrum and power delay profile. The achieved simulation results show that an adequate outdoor and indoor service can be provisioned at the considered frequencies. However, it is challenging to provide services to indoor user at 60 GHz using an outdoor base station even in such a small cell environment.
关键词： 3D ray tracing,multipath propagation,small cell,system performance,millimeter wave frequencies,5G
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Kiev (2018.7.2-2018.7.5)] 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Facet Model Processing for Complex Shape Object Scattering Calculation
摘要： The problem of construction a facet model of complex shape object for simulation of scattering electromagnetic is considered. It is proposed to use the approach of ray-tracing and kd-trees in order to take into account the re-reflections between some parts of the object. An algorithm for simplifying the geometric model of the object is proposed in order to reduce the time necessary for modeling. Comparison of calculated fields for identical objects, but with a different number of facets, showed that combining facets accelerates the simulation without violating its accuracy.
关键词： Complex shape object,RCS,facet,ray-tracing,kd-tree
更新于2025-09-23 15:21:01
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Visualizing light trapping within textured silicon solar cells
摘要： Random pyramids are the most widely used texture in commercial monocrystalline silicon solar cells to trap weakly absorbed photons with near-bandgap energies. There has been steady improvement in efforts to model the light-trapping performance of random pyramids, including a shift from an assumed pyramid base angle of 54.7° (ideal-random pyramids) to smaller values that are consistent with measured average angles. However, simulations have not yet considered the effects of a distribution of base angles (real-random pyramids), which all real textured wafers have. In this contribution, we benchmark the light-trapping capability of real-random pyramids against ideal-random pyramids and Lambertian scatterers by performing ray tracing of an accurate three-dimensional topographical map of the surface of a textured silicon wafer measured using atomic force microscopy. The angular distribution function (ADF) of light rays within the wafer, calculated at each pass as rays bounce between the front and rear surfaces, reveals that real-random pyramids are superior to ideal-random pyramids in trapping light precisely because of the distribution in their base angle. In particular, the ADF inside a wafer with real-random pyramids evolves to be Lambertian within just two passes—by the time (non-absorbed) light re-arrives at the front surface. Furthermore, the total path-length enhancement of light reaches nearly 60—exceeding that of a wafer with Lambertian surfaces—for narrow angles of incidence, though it falls short of the Lambertian reference for oblique angles.
关键词： atomic force microscopy,random pyramids,silicon solar cells,light trapping,Lambertian scatterers,ray tracing
更新于2025-09-23 15:19:57
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[IEEE 2019 4th Scientific International Conference Najaf (SICN) - Al-Najef, Iraq (2019.4.29-2019.4.30)] 2019 4th Scientific International Conference Najaf (SICN) - Study Evanescent-field Penetration Depth in Tapered Nano-fiber Optics
摘要： the use of etching in the fabrication of nanofiber optic (NFO) can enable the creation of thinner, longer, bundled, and strong wires. The aim of this etching methodology is to control the reduction of the core diameter and to demonstrate two different reducing methods applied to fabricate NFO. A large penetration depth of an evanescent field (EF) is the explanation of achievement for increasing a fiber-optic evanescent-field sensor (FOEFS). In general, the penetration depth (dp) of an optical fiber, stripped of its cladding, was a relation to the wavelength of the incident light, the refractive index (RI) of the surrounding medium and the incident angle on the basis of the ray-tracing model. Ray tracing analysis of tapered nano fiber optics segments and of combination taper probes make evident that the increases along the length of the taper, creating a segmented sensor with increased excitation light available at the surface for stimulating of ray transmitting. In this work, to study an NFO based on a tapered sensing probe by using the numerical analysis. The light power transmission and ultimate sensitivity of the element sensor are influenced by the incident angle, the numerical aperture (NA), core diameter, and taper ratio (TR). The TR of 0.1 and 0.7 are yield higher dp in certain regions. Then, the optimal result and the maximum dp were obtained with dp =1140 nm in TR=0.1 and a tapering length (L) of position tapering Z=40 mm.
关键词： fabricated nanofiber optics,ray tracing,tapered fiber optics,nanofiber optic sensors
更新于2025-09-23 15:19:57