الفهرس 
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Abstract
Citrus have been considered among horticultural crop that play a vital role at the level national economy, since they are ranked the first of fruits and third of major crops after cotton and rice consequently, they contribute in increasing the aggregate foreign cash required for financing the programs of economic and social development. They also constitute 35 % out of the fruit cultivated area in Egypt (The fifth Economical conference developing of Agricultural exports 1995 in Arabic Ref.). On the other hand, potato crop is one of the most important vegetable crops not only in Egypt but also in the world. This crop planted at 52 countries in the world and according to production volume potato is occupying the fourth place after wheat, rice and maize (Tyiitchev, 1986). Because of varying the vegetables and fruits in their natural characteristics such the quality of the fruits adversely affect thus, reducing the value of the final aggregate. Therefore, grading the fruits and vegetables is rapidly becoming one of the most important operations, which maintaining the fruit quality and raising the final price of product. There are many methods of grading fruits and vegetables such manual and mechanical grading. Mechanical grading may be classified based on the difference in physical parameters such as length, diameter, width and weight. The machine, which grades length, width and diameter, is more accurate and high throughputs for sphere and like sphere crops. But, it is fewer flexible when changing from one grading police to another, from variety to another and has no ability to grade fruits which oddly in shape. However, the weight grading do not rely on the geometry of the fruit, this method is particularly suitable to grade fruits or tubers which are oddly in shape. On the other side, the weight grading method have been required for passing each fruit singly onto measurement unit which consumes a 3.3 seconds (Radwan, 2000). So studying the geometry specific factors that influence on the productivity and efficiency of grading machines and introducing the modern technology in designing and manufacturing are one of the important items in this field which can be used to solve this problem.