فهرست مطالب amir rajaei

Saffron is one of the most valuable crops on the planet and the most expensive agricultural and medicinal product globally; this plant has a special place among the industrial and export products of Iran. One of the challenges in the production of this plant is timely harvest from the ground as well as red stigmas (branches) separating from other parts of saffron because the flowers are harvested in a brief period. Further, harvesting and separating at a limited time is a critical point. This research has been tried with the help of image processing techniques to discuss and recognize saffron flowers and how to identify them on the ground. In the first step, saffron flowers are recognized by transforming colored spaces. Then, the histogram and the minimum threshold are used to segment and remove extra pixels. For this purpose, to identify flowers, RGB space is converted to YCbCr space, and the combination of HSI and YCbCr color space is used to distinguish other objects in the image; also, a histogram of Cb component for early identification of saffron flowers are used. Then, those pixels which are misidentified are removed by the threshold value. Next step, the saffron flower needle-shaped leaves that are placed on the flowers are restored by morphological operation of the proposed method, and the flowers that overlap are removed. Then, the type of saffron flower (bud, broken, open flower) is determined, and the ability of harvest or suitability of saffron flowers for harvesting has been determined. Finally, the flower center that can be harvested is recognized and used by the saffron harvesting robot. Average results with respect to the accuracy, recall, F-measure, correctness, and correlation coefficient were 99.79, 99.42, 99.60, 99.91, and 99.50 achieved by the proposed method, respectively.

One of the issues that researchers have always considered in the design of storage dams is reducing the kinetic energy of flow passing through the spillways to control the velocity, reduce the destructive energy, and scour depth downstream of spillways. Stepped chutes and flip buckets are the most common energy dissipator structures in emergency spillways at dams. Regarding the effect of scour depth at downstream of these structures on their stability and safety, in the present study, the effect of hydraulic and geometric parameters on variations of scour characteristics downstream of smooth and stepped chutes was investigated experimentally. Experiments were conducted at a hydraulic lab at the University of Guilan in 2020-2021 with a ratio of critical flow depth and step height (yc/h) of 0.53-0.97, bucket exit angles of 15° and 30°, the ratio of tailwater and critical flow depth (ht/yc) ranging from 1.5–2, the ratio of height falling and step height (HF/h) varied in the range of 2-4, and a spillway slope of 1:2 (V: H). The comparison of results demonstrated that implementing steps over a smooth chute profile reduced maximum downstream scour depth of the flip bucket by 15° and 30° exit angles in comparison with a smooth chute for the minimum relative critical flow depth by 22 and 41 percent, respectively, and for the maximum relative critical flow depth, by 14 and 20 percent, respectively. Also, with an increase in the exit angle from 15° to 30°, the maximum scour depth decreases for the minimum and maximum tailwater depths by an average of 18 and 11 percent, respectively, for a smooth chute and by an average of 19 and 17 percent, respectively, for a stepped chute. Furthermore, a regression relationship was derived for predicting the scour depth at downstream of stepped chutes with the flip bucket.