The purpose of this work was an attempt to monitor the ripeness process and to investigate the different maturity stages of jackfruit by chemometric treatment of the data obtained from the disposable sensor. Response of the sensor strip fabricated using screenprinting technology was analyzed using Principal Component Analysis (PCA) and the classification model constructed by means of Canonical Discriminant Analysis (CDA) enable unknown maturity stages of jackfruit to be identified. Results generated from the combination of the two classification principles show the capability and the performance of the sensor strip towards jackfruit analysis.

The basic mathematics and structure of heliostat have remained unchanged for many decades. Following the challenge first made by Ries et al., the non-imaging focusing heliostat recently proposed by Chen et al. provides an alternative in the field of concentrated solar energy. This paper investigates the performance of a heliostat field composed of the newly proposed heliostats. In contrast to the dynamic curvature adjustment proposed in our previous work for a solar furnace, a fixed asymmetric curvature is used here with the spinning-elevation tracking method. This restriction is intended to equalize the manufacture cost of the new heliostat with that of traditional heliostats with azimuth-elevation tracking and spherical curvature. Fixing the curvature results in only partial aberration correction, compared to full correction using the dynamic adjustment of curvature. Nevertheless, the case studies presented in this paper show that the new heliostat design can reduce the receiver spillage loss by 10–30%, and provide a much more uniform performance without large variations with time of day.

Abstract The most general form of solar tracking formulae of an arbitrarily oriented heliostat toward an arbitrarily located target on the Earth is presented. With this complete solution, the used azimuth-elevation, spinning-elevation tracking formula, etc., are the special cases of it. Therefore, more application may be sought out for many individual cases in solar engineering. The new form of tracking solution could bring changes in the geometry and structure of the design of heliostat to meet various requirements.