- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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While rotating while cloaking
摘要： Invisible optical and thermal cloaking have been explored as the typical demonstrations of the transformation optics and thermotics theory. However, the existing cloaks are realized by only one-coordinate transformation, and the cloaking layout, i.e. the form of electromagnetic wave/heat passing around the invisible region, is single for a long time. Here, we propose a new rotated thermal cloak which can unify the conventional cloaking and rotating together, and realize the while-rotating–while-cloaking effect. The required anisotropic thermal conductivity tensor is deduced from the new geometric mapping. Though rotated, the heat ?ux can be tuned around the central invisible region perfectly by the proposed rotated thermal cloak. The underlying physics is explored by comprehensive analysis of the distribution of the thermal conductivity tensor, which is further compared with those of the conventional cloak and rotator. The experimental feasibility is also discussed by validating the practical while-rotating–while-cloaking effect through a proof-of-concept design. The proposed rotated thermal cloak is expected to extend the possibility of cloaking scheme, and open avenues for the multiple coordinate transformation in counterpart physical ?elds, like optics, electrics, acoustics, magnetics, mechanics, etc.
关键词： Coordinate transformation,Thermal rotator,Thermal cloak,Transformation thermotics
更新于2025-09-23 15:22:29
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Orientation Dependence of Elastic and Piezoelectric Properties in Rhombohedral BiFeO3
摘要： Through a coordinate transformation approach, crystal orientation dependences of elastic and piezoelectric properties at room temperature have been investigated in a three-dimensional space for rhombohedral bismuth ferrite (BiFeO3). Elastic constants (stiffnesses) c11', c12', c13' and piezoelectric constants d15', d31', d33' along arbitrary orientations were obtained based on crystalline asymmetry characteristics of 3m point group BiFeO3. Parameters along specific orientations obtaining the largest values were presented. The max c11' = 213 × 10^9 N/m^2 could be achieved in planes with φ = 0° and 90°. The max c12' = c13' = 132.2 × 10^9 N/m^2 could be achieved along directions at θ = 13° and θ = 77° inside three mirror planes, respectively. The max d15' = 27.6 × 10^{-12} C/N and the max d31' = 12.67 × 10^{-12} C/N could be both obtained along directions at θ = 69° inside mirror planes. The max d33' = 18 × 10^{-12} C/N could be obtained at θ = 0°, along the spontaneous polarization axis. By adopting optimal directions, the elastic and piezoelectric parameters of BiFeO3 could be significantly enhanced which shows applications for the growth of BeFeO3 films with preferred orientations and enhanced properties.
关键词： piezoelectricity,coordinate transformation,orientation dependence,bismuth ferrite,elasticity
更新于2025-09-23 15:22:29
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A flexible procedure to avoid the boundary materials singularities in 2D transformation-based cloaks
摘要： An out-of-plane coordinate transformation can avoid singular materials in a two-dimensional electromagnetic cloak. Based on numerical simulations of elliptical cylinders, in this paper we show that the use of two different constants to define the out-of-plane stretching can result in anisotropic materials with lower values and yet with a better scattering reduction for a given incident wave direction.
关键词： scattering cross-width,Cloaking,coordinate transformation,electromagnetic metamaterials
更新于2025-09-23 15:21:21
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Study on subsidence monitoring technology using terrestrial 3D laser scanning without a target in a mining area: an example of Wangjiata coal mine, China
摘要： When using a Terrestrial 3D laser scanning (TLS) to monitor the mining subsidence in a mining area, the conventional methods are to set up the public target manually, or to set up the ground control network in advance. However, these have the disadvantages of high labor intensity and low efficiency. In order to overcome the shortcomings of the conventional methods, this paper presents the subsidence monitoring method using TLS without a target in the mining area. Feature points are used to splice the multi-station point clouds in the same phase, and a few station coordinates are used to uniformly transform the multiphase data into a geodetic coordinate system. Afterwards, the surface digital elevation model (DEM) is established by using the point clouds after coordinate transformation, and the dynamic subsidence value and subsidence basin during the period of observation are obtained by DEM subtraction. Compared to traditional methods, this method simplifies the field measurement process, reduces the labor intensity, and transfers the main work to the internal industry. It is suitable for surface subsidence monitoring with a harsh external environment and complicated topographic conditions. Surface deformation values are important basic data for mining area subsidence parameters acquisition, mining area environmental assessment, land reclamation, and ecological restoration. As a consequence, it is of great value to popularize and apply in mining area for subsidence monitoring.
关键词： Coordinate transformation,Registration,Subsidence basin,3D laser scanning technology,Deformation monitoring
更新于2025-09-23 15:21:01
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Design of polarizers with smooth grooves by the coordinate transformation method for ECH&CD system
摘要： We investigate design of polarizers with smooth grooves for the electron cyclotron heating system in this paper. The coordinate transformation method is used and the boundary condition of the polarizer changes for a grooved one to a plane. For a certain polarizer, the shape function of grooves is represented as a Fourier series which is useful for numerical calculation. Two sinusoidal grooved polarizers and two trapezoidal grooved polarizers are designed with the coordinate transformation method and tested with the low power test platform. The test results agree well with the numerical results. The method mentioned in this paper can be used as an optional one for the polarizer design with smooth grooves.
关键词： Polarizers,ECH&CD,Fourier expanding,Coordinate transformation
更新于2025-09-19 17:15:36
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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) - A Novel Approach to Amine-Thiol Molecular Precursors for Fabrication of High Efficiency Thin Film CISSe/CIGSSe Devices
摘要： 3-D coordinate transformation, which is based on aligning two sets of common reference points, is frequently applied in large-scale combined measurement to unify coordinate frames and tie individual measurement systems together. However, it introduces uncertainty into the ?nal measurement results. This uncertainty must be quanti?ed to make the results complete. This paper presents a novel approach to the uncertainty analysis of 3-D coordinate transformation based on the weighted total least squares adjustment. This approach takes full account of the uncertainty characteristics of measuring instruments and is simple in calculation. In this approach, the transformation uncertainty of a point in a world frame is analyzed carefully. The simulations show that the transformation uncertainty has a distribution of concentric ellipsoids and is affected by the measurement uncertainties and layout of common points. Besides, strategies for minimizing transformation uncertainty are recommended. The experimental results from a laser tracker prove that this proposed approach is valid under normal instrument operating conditions and that these strategies are feasible and ef?cient.
关键词： Coordinate transformation,error analysis,uncertainty,large-scale metrology,position measurement,sensor fusion
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Dual-band tunable mid-infrared polarization converter based on U-shaped graphene metamaterial
摘要： 3-D coordinate transformation, which is based on aligning two sets of common reference points, is frequently applied in large-scale combined measurement to unify coordinate frames and tie individual measurement systems together. However, it introduces uncertainty into the ?nal measurement results. This uncertainty must be quanti?ed to make the results complete. This paper presents a novel approach to the uncertainty analysis of 3-D coordinate transformation based on the weighted total least squares adjustment. This approach takes full account of the uncertainty characteristics of measuring instruments and is simple in calculation. In this approach, the transformation uncertainty of a point in a world frame is analyzed carefully. The simulations show that the transformation uncertainty has a distribution of concentric ellipsoids and is affected by the measurement uncertainties and layout of common points. Besides, strategies for minimizing transformation uncertainty are recommended. The experimental results from a laser tracker prove that this proposed approach is valid under normal instrument operating conditions and that these strategies are feasible and ef?cient.
关键词： Coordinate transformation,error analysis,uncertainty,large-scale metrology,position measurement,sensor fusion
更新于2025-09-16 10:30:52
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Using Weighted Total Least Squares and 3-D Conformal Coordinate Transformation to Improve the Accuracy of Mobile Laser Scanning
摘要： With the aid of global position system (GPS), mobile laser scanning (MLS) is able to provide 3-D geo-referenced point cloud that has centimeter-level accuracy. The MLS accuracy, however, degrades signi?cantly due to the trajectory errors of the laser scanner and the residual systematic errors from the geo-referencing transformation process in the GPS-free environments. To solve this problem, this article presents a novel integration algorithm based on the weighted total least squares (WTLS) and the 3-D conformal coordinate transformation (3DCCT). In this new method, the 3-D point measurement model and the error propagation parameter vector in the MLS can be updated in real-time, and they can also adjust the geo-referenced coordinate transformation parameters and eliminate the in?uences of the residual systematic errors during MLS. In this article, the MLS mathematical model is ?rst established, followed up by a detailed analysis for MLS error budget interpreting the effects of the individual error sources. Second, WTLS is used to correct the 3-D point measurement model of MLS and the error of propagation parameter vector; 3DCCT, WTLS, and ground control target feature constraints are applied to eliminate the residual systematic errors in the geo-referencing transformation process. Finally, several data sets from outdoor scenarios are used to evaluate and validate the proposed method. The experimental results demonstrate that the proposed method can signi?cantly improve the overall accuracy of the MLS system.
关键词： mobile laser scanning (MLS),weighted total least squares (WTLS),3-D conformal coordinate transformation (3DCCT)
更新于2025-09-16 10:30:52