摘要 :
Regarding to the mistakes that optoelectronic devices such as CCD focal plane arrays devices are often placed on the exit port plane of integrating sphere source to perform calibration, the output irradiance uniformity of integrat...
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Regarding to the mistakes that optoelectronic devices such as CCD focal plane arrays devices are often placed on the exit port plane of integrating sphere source to perform calibration, the output irradiance uniformity of integrating sphere source is analyzed, the basis which rational using the integrating sphere source to calibrate the optoelectronic devices is obtained. Two theoretical output irradiance uniformity models based on numerical analysis method and Monte Carlo method are developed respectively. The models consider two fundamental situations of integrating sphere sources, namely (1) ideal lambertian source and (2) non-ideal lambertian source. The distribution regularity of irradiance uniformity was generalized by contrast of the theoretical data obtained by the models and the measured data obtained by two different actual integrating sphere sources. The results show that when (1) the diameter of optoelectronic device is less than half diameter of the sphere exit port, and (2)the ratio of the distance from device to exit port and the exit port diameter are between 3 and 5, a 99% better output irradiance uniformity can be obtained. The results provide a practical guide to ensure the accuracy of the calibration exercise of optoelectronic devices.
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The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continu...
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The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continuous spectrum light source. The wavelength accuracy of a monochromator is an important indicator of its performance, and the research of wavelength accuracy calibration methods to improve measurement accuracy is a hot theme for researchers around the world.When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared region, low-pressure discharged lamps, such as mercury lamps and neon lamps, are usually used to calibrate on the well-known limited atomic emission lines of lamp to obtain the wavelength deviation value at the wavelength points of these lines.For some high-precision requirements, for example, when measuring the spectral responsivity of a reference solar cell using a tunable laser as light source, it is difficult for these discrete and finite lines to fully satisfy the demand.To solve this problem, a new method based on combination of continuous spectrum light source and fourier transform spectroradiometer was used. A calibrated experimental optical path was successfully built, and the wavelength deviation values of 322 wavelength points from 400 nm to 2000 nm were obtained. The optimal measurement repeatability reached 0.3 pm, which met the need for high-precision measurement requirement. As a comparison, a low-pressure discharged lamp method was also used. Using a mercury lamp and a neon lamp, a wavelength calibration experiment was performed on the same monochromator in the same wavelength range, and only 20 wavelength deviation values were obtained at its atomic emission lines wavelength point. The number of wavelength deviation values is less than 6.5% of that of the new method.The new method proposed in this paper,which not only can significantly improve the quality of the monochromator calibration wavelength deviation values, but in which the obtained values are able to establish traceability to the international SI unit system, is an ideal wavelength accuracy calibration method.
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摘要 :
The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continu...
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The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continuous spectrum light source. The wavelength accuracy of a monochromator is an important indicator of its performance, and the research of wavelength accuracy calibration methods to improve measurement accuracy is a hot theme for researchers around the world.When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared region, low-pressure discharged lamps, such as mercury lamps and neon lamps, are usually used to calibrate on the well-known limited atomic emission lines of lamp to obtain the wavelength deviation value at the wavelength points of these lines.For some high-precision requirements, for example, when measuring the spectral responsivity of a reference solar cell using a tunable laser as light source, it is difficult for these discrete and finite lines to fully satisfy the demand. To solve this problem, a new method based on combination of continuous spectrum light source and fourier transform spectroradiometer was used. A calibrated experimental optical path was successfully built, and the wavelength deviation values of 322 wavelength points from 400 nm to 2000 nm were obtained. The optimal measurement repeatability reached 0.3 pm, which met the need for high-precision measurement requirement. As a comparison, a low-pressure discharged lamp method was also used. Using a mercury lamp and a neon lamp, a wavelength calibration experiment was performed on the same monochromator in the same wavelength range, and only 20 wavelength deviation values were obtained at its atomic emission lines wavelength point. The number of wavelength deviation values is less than 6.5% of that of the new method.The new method proposed in this paper,which not only can significantly improve the quality of th
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For the optical guidance system flying at low altitude and high speed, the calculation of turbulent convection heat transfer over its dome is the key to designing this kind of aircraft. RANS equations-based turbulence models are o...
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For the optical guidance system flying at low altitude and high speed, the calculation of turbulent convection heat transfer over its dome is the key to designing this kind of aircraft. RANS equations-based turbulence models are of high computation efficiency and their calculation accuracy can satisfy the engineering requirement. But for the calculation of the flow in the shock layer of strong entropy and pressure disturbances existence, especially of aerodynamic heat, some parameters in the RANS energy equation are necessary to be modified. In this paper, we applied turbulence models on the calculation of the heat flux over the dome of sphere-cone body at zero attack. Based on Billig's results, the shape and position of detached shock were extracted in flow field using multi-block structured grid. The thermal conductivity of the inflow was set to kinetic theory model with respect to temperature. When compared with Klein's engineering formula at the stagnation point, we found that the results of turbulent models were larger. By analysis, we found that the main reason of larger values was the interference from entropy layer to boundary layer. Then thermal conductivity of inflow was assigned a fixed value as equivalent thermal conductivity in order to compensate the overestimate of the turbulent kinetic energy. Based on the SST model, numerical experiments showed that the value of equivalent thermal conductivity was only related with the Mach number. The proposed modification approach of equivalent thermal conductivity for inflow in this paper could also be applied to other turbulence models.
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摘要 :
For the optical guidance system flying at low altitude and high speed, the calculation of turbulent convection heat transfer over its dome is the key to designing this kind of aircraft. RANS equations-based turbulence models are o...
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For the optical guidance system flying at low altitude and high speed, the calculation of turbulent convection heat transfer over its dome is the key to designing this kind of aircraft. RANS equations-based turbulence models are of high computation efficiency and their calculation accuracy can satisfy the engineering requirement. But for the calculation of the flow in the shock layer of strong entropy and pressure disturbances existence, especially of aerodynamic heat, some parameters in the RANS energy equation are necessary to be modified. In this paper, we applied turbulence models on the calculation of the heat flux over the dome of sphere-cone body at zero attack. Based on Billig's results, the shape and position of detached shock were extracted in flow field using multi-block structured grid. The thermal conductivity of the inflow was set to kinetic theory model with respect to temperature. When compared with Klein's engineering formula at the stagnation point, we found that the results of turbulent models were larger. By analysis, we found that the main reason of larger values was the interference from entropy layer to boundary layer. Then thermal conductivity of inflow was assigned a fixed value as equivalent thermal conductivity in order to compensate the overestimate of the turbulent kinetic energy. Based on the SST model, numerical experiments showed that the value of equivalent thermal conductivity was only related with the Mach number. The proposed modification approach of equivalent thermal conductivity for inflow in this paper could also be applied to other turbulence models.
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It's difficult to detect LSS(Low-Small-Slow) target because of its overturning, distortion during movement. Aiming at this problem, this paper proposes a LSS target tracking algorithm based on optical flow detection and polynomial...
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It's difficult to detect LSS(Low-Small-Slow) target because of its overturning, distortion during movement. Aiming at this problem, this paper proposes a LSS target tracking algorithm based on optical flow detection and polynomial fitting relocation. Firstly, target is detected by optical flow method, and then the SVM classifier trained with hog feature and color histogram feature is used to eliminate the false target. Then use TBD strategy to process the target information in the first three frames to confirm the initial location of the target. In follow-up tracking process, the obtained target information is compared with polynomial fitting results to determine whether to trigger the relocation mechanism. In relocation mechanism, the hot spot region will be generated according to the polynomial fitting results, and the salient features of the hot spot region will be extracted to determine the target location. Through the performance on the public data set LaSOT and the image sequence collected by the author, the algorithm in this paper is insensitive to the maneuver and distortion of LSS targets, and the tracking effect is stable. Under certain constraints, the tracking accuracy of the algorithm can reach more than 96%, which has strong application value.
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摘要 :
It's difficult to detect LSS(Low-Small-Slow) target because of its overturning, distortion during movement. Aiming at this problem, this paper proposes a LSS target tracking algorithm based on optical flow detection and polynomial...
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It's difficult to detect LSS(Low-Small-Slow) target because of its overturning, distortion during movement. Aiming at this problem, this paper proposes a LSS target tracking algorithm based on optical flow detection and polynomial fitting relocation. Firstly, target is detected by optical flow method, and then the SVM classifier trained with hog feature and color histogram feature is used to eliminate the false target. Then use TBD strategy to process the target information in the first three frames to confirm the initial location of the target. In follow-up tracking process, the obtained target information is compared with polynomial fitting results to determine whether to trigger the relocation mechanism. In relocation mechanism, the hot spot region will be generated according to the polynomial fitting results, and the salient features of the hot spot region will be extracted to determine the target location. Through the performance on the public data set LaSOT and the image sequence collected by the author, the algorithm in this paper is insensitive to the maneuver and distortion of LSS targets, and the tracking effect is stable. Under certain constraints, the tracking accuracy of the algorithm can reach more than 96%, which has strong application value.
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摘要 :
The monochromators, which are able to separate a specific wavelength light from a complex spectrum and a continuous spectrum light source, have been widely used in optical measurements. As one crucial specification, wavelength acc...
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The monochromators, which are able to separate a specific wavelength light from a complex spectrum and a continuous spectrum light source, have been widely used in optical measurements. As one crucial specification, wavelength accuracy has always been a research theme for monochromator users around the world. When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared regions, low-pressure discharged lamps, such as mercury lamps, are usually employed to obtain wavelength deviations at certain wavelength points of atomic emission lines of lamps,which are well-known recognized. For the requirement of monochromator wavelength calibration, a light path based on the low-pressure discharged lamp method was constructed. Three strong radiation flux lines of the mercury lamps were selected and tested,whose wavelength values were 365.015 nm, 435.833 nm, and 546.075 nm. Meanwhile a new method based on continuous spectrum light source and Fourier transform spectrometer was proposed and light path was also built. Near the wavelength value points of the selected atomic emission lines of mercury lamp, a measurement experiment was performed both on the same monochromator and the same experimental conditions, and the wavelength deviation values of the monochromator was obtained. The consistency of the two methods was good, and the best repeatability error was better than 0.005nm. The work of this article is of positive for those measurement laboratories to select suitable approach to perform their monochromators wavelength calibrations.
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Spectral mismatch error should be carefully considered during the calibration of solar cells by means of solar simulator and calibrated reference cell. Even test and reference cells with the same type should be also considered spe...
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Spectral mismatch error should be carefully considered during the calibration of solar cells by means of solar simulator and calibrated reference cell. Even test and reference cells with the same type should be also considered spectral mismatch error to achieve good measurement results. Spectral mismatch error can be calculated with the relative spectral response of the test and reference cells, and the relative spectral irradiance of the simulator and reference solar. The reference solar spectral irradiance distribution was given according to IEC60904-3:2008. Experimental results, two cells, one test and one ref, with two different spectra solar simulators, were presented. The calculation method and experimental data presented could be positive reference to photovoltaic labs to obtain good calibration and test results of solar cells.
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摘要 :
Spectral mismatch error should be carefully considered during the calibration of solar cells by means of solar simulator and calibrated reference cell. Even test and reference cells with the same type should be also considered spe...
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Spectral mismatch error should be carefully considered during the calibration of solar cells by means of solar simulator and calibrated reference cell. Even test and reference cells with the same type should be also considered spectral mismatch error to achieve good measurement results. Spectral mismatch error can be calculated with the relative spectral response of the test and reference cells, and the relative spectral irradiance of the simulator and reference solar. The reference solar spectral irradiance distribution was given according to IEC60904-3:2008. Experimental results, two cells, one test and one ref, with two different spectra solar simulators, were presented. The calculation method and experimental data presented could be positive reference to photovoltaic labs to obtain good calibration and test results of solar cells.
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