- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Seismic-physical Modeling Using a Micro Quasi-Michelson Fiber-optic Interferometer
摘要： A micro fiber-optic interferometer was proposed and demonstrated experimentally. The device only comprised a fiber-optic taper containing a refractive index modification (RIM) region that was written by a femtosecond laser. The coupling and recoupling of core-to-cladding modes were improved by the RIM to be 'window-like'. A well-defined interference spectrum was obtained because of the interference between the recoupled high-order modes, based on the quasi-Michelson interference mechanism. Using the spectral-side band filtering technology, the ultrasonic wave (UW) was detected with a high sensitivity by the proposed interferometer. The key to the success of the sensor is that the micro taper sensing fiber is more easily stretched by the UW-induced strain. Moreover, the interferometer was equipped with a cone-shaped horn to further promote the UW sensitivity of the sensor due to its acoustic focusing performance. This sensor offers a better method to realize seismic-physical modeling by scanning detection and reconstructing the echoes.
关键词： Fiber sensor,ultrasonic wave imaging,physical model
更新于2025-09-23 15:22:29
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Computer and Experimental Modelling of Heat Leakage from Porous Substrates of LED Lighting Devices
摘要： In this paper we propose a mathematical and physical model of a porous substrate, evaluate influence of the pores size and quantity on the substrate’s specific surface and present experimental results of the heat leakage kinetics by the porous substrate. Performances of the porous aluminium oxide printed circuit board with the record heat conductivity of 120 W/mK are presented.
关键词： porous substrate,printed board,physical model,heat conductivity,LED lighting device
更新于2025-09-12 10:27:22
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Cloud Shadow Removal Based on Cloud Transmittance Estimation
摘要： This paper proposes a method of cloud shadow removal for multispectral images to retrieve the ground reflectance of areas shadowed by clouds. Cloud shadows are cast when incident direct solar irradiance gets attenuated by clouds. To retrieve the ground reflectance of the shadowed pixels, it is required to estimate pixel-wise attenuation factor for the solar irradiance. Unlike conventional methods, the proposed technique takes the physical model of cloud shadow formation into account to accurately estimate the attenuation factors. According to the physical model, the factors are derived from the transmittance of an occluding cloud. Visual and quantitative results demonstrate that the proposed method outperforms the well-known de-shadowing algorithm. The average correlation coefficient of the corrected image with a reference image is improved from 0.45 to 0.75 by the proposed method as compared to the conventional method. Further, the average spectral angle with a reference image is improved by 10%.
关键词： shadow removal,Cloud,physical model,spectral unmixing
更新于2025-09-10 09:29:36
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Mathematical Modeling and Accuracy Testing of WorldView-2 Level-1B Stereo Pairs without Ground Control Points
摘要： With very high resolution satellite (VHRS) imagery of 0.5 m, WorldView-2 (WV02) satellite images have been widely used in the field of surveying and mapping. However, for the specific WV02 satellite image geometric orientation model, there is a lack of detailed research and explanation. This paper elaborates the construction process of the WV02 satellite rigorous sensor model (RSM), which considers the velocity aberration, the optical path delay and the atmospheric refraction. We create a new physical inverse model based on a double-iterative method. Through this inverse method, we establish the virtual control grid in the object space to calculate the rational function model (RFM) coefficients. In the RFM coefficient calculation process, we apply the correcting characteristic value method (CCVM) and least squares (LS) method to compare the two experiments’ accuracies. We apply two stereo pairs of WV02 Level 1B products in Qinghai, China to verify the algorithm and test image positioning accuracy. Under the no-control conditions, the monolithic horizontal mean square error (RMSE) of the rational polynomial coefficient (RPC) is 3.8 m. This result is 13.7% higher than the original RPC positioning accuracy provided by commercial vendors. The stereo pair horizontal positioning accuracy of both the physical and RPC models is 5.0 m circular error 90% (CE90). This result is in accordance with the WV02 satellite images nominal positioning accuracy. This paper provides a new method to improve the positioning accuracy of the WV02 satellite image RPC model without GCPs.
关键词： WorldView-2,physical model,rational function model,very high-resolution satellites
更新于2025-09-09 09:28:46