A Spectrum Correction Method Based on Optimizing Turbulence Intensity

Based on the classical spectral representation method of simulating turbulent wind speed fluctuation, a harmonic superposition algorithm was introduced in detail to calculate the homogeneous turbulence wind field simulation in space. From the view of the validity of the numerical simulation results in MATLAB and the simulation efficiency, this paper discussed the reason for the bias existing between three types of turbulence intensity involved in the whole simulation process: simulated turbulence intensity, setting reference turbulence intensity, and theoretical turbulence intensity. Therefore, a novel spectral correction method of a standard deviation compensation coefficient was proposed. The simulation verification of the correction method was carried out based on the Kaimal spectrum recommended by IEC61400-1 by simulating the uniform turbulent wind field in one-dimensional space at the height of the hub of a 15 MW wind turbine and in two-dimensional space in the rotor swept area. The results showed that the spectral correction method proposed in this paper can effectively optimize the turbulence intensity of the simulated wind field, generate more effective simulation points, and significantly improve the simulation efficiency.

The linearization of the relationship between scene luminance and digital camera output levels

This paper presents the results of linearity testing of the integrated image sensor of a CCD-equipped digital camera. The study demonstrated the lack of linearity of the characteristics of the sensor when scaling with the luminance standard signal. In the course of the research the function approximated by the fifth-degree polynomial was determined. After the appropriate transformation, this function would enable the linearization of the signal from the studied image sensor. The study demonstrated the possibility of linearizing the signal of integrated image sensors for correct luminance measurements. Thus, the possibility of reducing the nonlinearity error of integrated image sensors was discussed. Full Text: PDF ReferencesT. Tashiro, S. Kawanobe, T. Kimura-Minoda, S. Kohko, T. Ishikawa, and M. Ayama, "Discomfort glare for white LED light sources with different spatial arrangements," Lighting Research and Technology, vol. 47, no. 3, pp. 316-337, 2015, doi: 10.1177/1477153514532122. 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