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The aim of this paper is to study the effect of dissimilarity of the intrinsic characteristics of the light dependent resistor (LDRs) on optical sun tracking systems, designed for solar power concentration applications such as parabolic trough collectors, Fresnel mirrors concentrators, and concentrated photovoltaic, a comparative study was done between a sun tracker based on LDRs chosen randomly with and without an initial calibration of the offsets, and a sun tracker based on LDRs selected meticulously thanks to a black box test bench, developed especially for this purpose. By choosing two light dependent resistors randomly, the dissimilarity between them can reach 23.2%, which cause a bad sun tracking even with initial offset calibration, in the other hand, and by the use of selected LDRs using the test bench, the dissimilarity drops to 0.06%, which meets requirements of solar power concentration systems. [ABSTRACT FROM AUTHOR]

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This paper presents an in situ moisture content sensor based on a switched-polarization dipole antenna that detects the magnitude of mutual coupling between perpendicular and parallel polarizations. Three aspects of the sensor development are presented: a new closed-form calculation of mutual impedance of perpendicular polarization dipole antenna, an antenna design, and an investigation of performance enhancement. As the sensor detects only the magnitude of mutual coupling, it is low cost and low profile and needs less processing time. Thus, it is suitable for a closed-loop drying system. Our study has shown that the values of the dielectric constants measured by this sensor are comparable to the reference values from the transmission line technique in the previous work. However, there are significant differences in the values of the dielectric loss factors because the structure of the presented sensor is not a closed boundary like the transmission line sensor. Therefore, error compensation has been developed to correct the results. This sensor, in a closed-loop drying system, has shown good performance for in situ monitoring and real-time monitoring. Consequently, it is very suitable for monitoring the moisture content of paddy (rough rice). [ABSTRACT FROM AUTHOR]