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Zhao F.,Key Laboratory of Precision Opto mechatronics Technology | Zhao F.,CAS Institute of Remote Sensing Applications | Gu X.,CAS Institute of Remote Sensing Applications | Verhoef W.,National Aerospace Laboratory Netherlands | And 6 more authors.
Remote Sensing of Environment | Year: 2010

A computationally efficient reflectance model for row planted canopies is developed in this paper through separating the contributions of incident direct and diffuse radiation scattered by row canopies. The row model allows calculating the reflectance spectrum in any given direction for the optical spectral region. The performance of the model is evaluated through comparisons with field measurements of winter wheat as well as with an established 3D computer simulation model. Especially the systematic comparisons with the computer simulation model demonstrate that the model can adequately simulate the characteristic distribution of directional reflectance factors of row canopies, which is shown in the polar map of reflectance as a high or low value stripe approximately parallel to the row orientation, besides the hotspot effect. Physical mechanisms causing the dynamics were proposed and supported by comparison studies. The features of reflectance distributions of row canopies, which are distinctively different from those of homogeneous canopy, imply that it is problematic to use one-dimensional radiation transfer model to interpret radiation data and estimate the structural or spectral parameters of row canopies from reflectance measurements. Finally, further improvements needed for the current model are briefly discussed. © 2009 Elsevier Inc. Source


Wei D.,China Aerospace Geophysical Survey and Remote Sensing Center for Land and Resources | Gan F.,China Aerospace Geophysical Survey and Remote Sensing Center for Land and Resources | Zhang Z.,China Aerospace Geophysical Survey and Remote Sensing Center for Land and Resources | Xiao C.,China Aerospace Geophysical Survey and Remote Sensing Center for Land and Resources | And 6 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015

Infrared spectrums play an important role in the information extraction of rock and minerals. Spectrum simulation is a fundamental issue of land surface scene simulation and image simulation of remote sensing systems. Signal to Noise Ratio is regarded as an essential parameter of instrument and remote sensing image. In this study, we used MODTRAN to simulate apparent radiance and different levels of additive white Gaussian noise was added to the simulated spectrum. In the section of noise impact on object recognition, Spectral Feature Fitting was chosen to compare the fit of simulated spectra with different noise levels to reference apparent radiance spectra without noise. Relative error is also calculated for the accuracy assessment which is helpful for validation and improvement of instrument parameters. © 2015 IEEE. Source


Zhanshe G.,Beihang University | Zhanshe G.,Key Laboratory of Precision Opto mechatronics Technology | Zhanshe G.,Key Laboratory of Inertial Science and Technology for National Defence | Zhou F.,Beihang University | And 8 more authors.
Microsystem Technologies | Year: 2011

This paper introduces a new theoretical model of plate capacitor for MEMS comb actuator. In this model, bulk fabrication process and edge effect are both considered using integration method and conformal transformation theory. In order to verify the correctness of the model, FEM software is used to calculate the value of the capacitance of the MEMS comb actuator. The simulated result is 1.441 pF. Relative errors to the model calculated result 1.401 pF and ideal model calculated result 1.267 pF are 2.78 and 12.07% respectively. Then, high precision capacitance measuring device is used to measure the micro-fabricated comb actuator. The tested result is 1.517 pF. Its relative error to the rectified value is 7.65%, much less than the relative error to ideal result 16.48%. This further indicates the correctness of the rectified model. © 2010 Springer-Verlag. Source


Jie J.,Key Laboratory of Precision Opto mechatronics Technology | Guangjun Z.,Key Laboratory of Precision Opto mechatronics Technology | Zhiming W.,Key Laboratory of Precision Opto mechatronics Technology | Qiaoyun F.,Key Laboratory of Precision Opto mechatronics Technology | Xinguo W.,Key Laboratory of Precision Opto mechatronics Technology
Optics and Lasers in Engineering | Year: 2010

A novel attitude sensor optical system employing a microlens array (MLA) based on the Fraunhofer diffraction theory was developed. To analyze the irradiance distribution of the focal plane, a mathematic model was established by using the Fresnel-Kirchhoff formula. A numerical simulation showed that this optical system provided high accuracy and would ensure a large field of view. © 2009 Elsevier Ltd. All rights reserved. Source


Guo Z.-S.,Beihang University | Guo Z.-S.,Key Laboratory of Precision Opto mechatronics Technology | Feng Z.,Beihang University | Feng Z.,Key Laboratory of Precision Opto mechatronics Technology | And 6 more authors.
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2010

With plate capacitor theory and calculus method, the capacitance of micro electro-mechanical system (MEMS) electrostatic comb actuator is studied. Considering the affections of fabrication technology and edge effect, a calculating model is built, by which the calculations for the fabricated comb actuator are carried out under the ideal condition and the condition of considering border effect and fabricating technology. The calculated results are 1.2673 pF and 1.4403 pF respectively, of which the relative errors with the high precision LCR device measured value 1.5172 pF are 16.47% and 5.07%. This indicates that the model can be used to get higher precision, if the border effect and fabrication process are taken into account. Source

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