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Showing 2 results for Shahifar
Anita Shahifar, Zahra Ghasemi, Reza Shahifar,
Volume 13, Issue 1 (1-2024)
Abstract
Chitin is an important natural polysaccharide that is found in the cell wall of some organisms including crustaceans. The chitosan polymer, which is extracted from chitin, plays a very important role in the production of a wide range of materials used in food products. The present study aimed to extract chitin from the shell of the farmed shrimp Penaeus vannamei using the chemical method, through the steps of deproteinization, demineralization and deacetylation and using it as a natural coating with no negative effects, for protecting the covering of the fruits. To ensure the standard and determine the quality of the chitosan synthesized, FT-IR test was performed. Then, grape and strawberry fruits were covered by chitosan concentrations of zero (control sample), 0.2 and 0.5% as different treatments. During the two-month storage period at 0-4 degrees Celsius, and to control of the changes in the fruits, the appearance quality factors in fruits were controlled weekly. Based on the results, the efficiency of chitin production from the shell was 58%, chitosan production from chitin was 84% and therefore, the efficiency of chitosan production from the shell was 48%, which is a suitable rate. The control samples of both fruits lost their appearance and shriveled in the first week of the test, and spoiled after three weeks. However, in bothe grapes and strawberries coated with dissolved chitosan with a concentration of 0.5%, the best antibacterial coating was created for the fruits and their appearance quality was maintained during the storage period of two months.
Volume 23, Issue 7 (July 2023)
Abstract
In this paper, a finite-time fault tolerant controller based on sliding mode algorithm, as a robust control method, is presented to control the attitude stabilization of the quadrotor system in the presence of actuator fault and uncertainty. The controller is designed based on the nonlinear model of a quadrotor and its stability analysis is performed according to the Lyapunov stability theorem. Also, regarding some weaknesses of MEMS sensors such as partly high noise and bias error, an extended Kalman filter is designed and implemented in order to merge sensors data and reduce the noise effect on the outputs. To validate the controller performance, the experimental tests is implemented on a full-scale quadrotor in real-time. The evaluation of the designed strategy is carried out in different scenarios, no fault in the actuators and a partial loss of effectiveness of an actuator as well as uncertainty in the quadrotor parameters. The experimental results reveal the superiority of the sliding mode tolerant strategy over feedback linearization in the presence of various faults and uncertainty effects.
