Non-destructive technologies for fruit and vegetable size determination - a review

Here, we review different methods for non-destructive horticultural produce size determination, focusing on electronic technologies capable of measuring fruit volume. The usefulness of produce size estimation is justified and a comprehensive classification system of the existing electronic techniques to determine dimensional size is proposed. The different systems identified are compared in terms of their versatility, precision and throughput. There is general agreement in considering that online measurement of axes, perimeter and projected area has now been achieved. Nevertheless, rapid and accurate volume determination of irregular-shaped produce, as needed for density sorting, has only become available in the past few years. An important application of density measurement is soluble solids content (SSC) sorting. If the range of SSC in the batch is narrow and a large number of classes are desired, accurate volume determination becomes important. A good alternative for fruit three-dimensional surface reconstruction, from which volume and surface area can be computed, is the combination of height profiles from a range sensor with a two-dimensional object image boundary from a solid-state camera (brightness image) or from the range sensor itself (intensity image). However, one of the most promising technologies in this field is 3-D multispectral scanning, which combines multispectral data with 3-D surface reconstructio

Selecting between Competitors in Multiplication Tasks: An Explanation of the Errors Produced by Adolescents with Learning Difficulties

Two experiments were conducted in order to determine the nature of the difficulties encountered by learning disabled (LD) adolescents in the resolution of multiplication problems ( a b, where a and b vary between 2 and 9). A response production task (Experiment 1) revealed that the incorrect responses generally belonged to the table of one of the two operands, and that the order of difficulty of the problems was the same for the LDs as for normal children, adolescents, and educated adults as reported in the literature. This result suggests that the difficulties are not solely due to memory problems. Experiment 2 tested the hypothesis that these difficulties were caused by a problem in inhibiting the incorrect responses from a set of possible responses. Subjects completed a multiple response task in which the correct response was presented along with three distractors. The level of interference between the correct response and the distractors was varied by manipulating the nature of the distractors (Null Interference, NI: numbers that did not belong to the multiplication table; Weak Interference, WI: numbers belonging to other tables than those of a and b; Strong Interference, SI: numbers belonging to the tables of either a or b). The SI condition resulted in a higher level of errors than the NI and WI conditions and there was no difference between these latter two conditions. This result suggests that the main difficulty encountered by LD subjects is associated with inefficient inhibition of incorrect responses. Thus, the mobilisation of inhibitory processes seems to be an important stage in the development of multiplication skills. </jats:p