A common method for controlling a group of parallel converters in decentralized control strategy structure in an island microgrid, the use is the droop-down characteristics of frequency ω-P and voltage E-Q. However, the problem with using this method is that the reactive power is not properly distributed (in proportion to the capacity of the micronutrients) between the micronutrients, which may lead to overload in the converters. Microgrids may also suffer from dynamic stability problems such as power fluctuations, which can be increased by switching between active and reactive power control. To avoid this problem, the X / R ratio of transmission lines is an important parameter that should be carefully considered in the design of micronutrient controllers. By linearizing and simplifying conditions, the control system conversion function model becomes a single input-single output system, which is efficient enough to show the relationship between control parameters such as slope of droop characteristics and derivative sentences, virtual impedance, and voltage controllers. Using this model, stability conditions for different parameters are analyzed. Also, to improve power distribution stability, common droop strategies are modified by adjusting the slope as well as adding nonlinear sentence sections. This approach reduces the coupling between active and reactive power control and reduces the dependence of power distribution on grid parameters such as the X / R ratio. To evaluate the reliability of the proposed model, the simulation results in a sample island microgrid in MATLAB software are presented.

Background: Arterial occlusions are divided as acute and chronic. Emboli is the most common cause of acute arterial occlusion, which is treated by perforating embolectomy using fogarty catheter. Some of these cases that are not diagnosed in early phase of the disease (within the first month), should be treated using open surgical techniques, since embolectomy via fogarty catheter is not effective in such instances. Case report: In this study we reported a 55 years old lady with subclavian-axillary artery occlusion who was suffered from critical limb ischemia. For the first time in Iran we used Rotator-Aspirer appreture for thrombectomy in this patient.Conclusion: Following the intervention, distal pulses were pulpated and ischemic signs and symptoms faded completely.

The series robots have nonlinear dynamics with together uncertainties in joints’ forces and robot’s model. For the fuzzy control, two parameters of angular position and angular velocity are usually used as the linguistic variables. This method is similar the PD controller, and, consequently it cannot track a desired trajectory and it have a steady-state error. In the present paper the summation of errors is additionally used as a linguistic variable. Using three linguistic variables of error, error derivative and error integration for the angular position, trajectory tracking of a RR series robot is performed for its uncertain dynamic model. This method is similar the PID controller, and, consequently it can track a desired trajectory. Additionally, the presented fuzzy PID controller is not sensitive to the noise and uncertainty, and, it presents better results than a classic PID controller

Evaluating the cutting rate (CR) of stones is important in the cost estimation and the planning of the stone processing plants. This research used regression models to estimate the stones’ CR based on their physico-mechanical characteristics. Stone processing factories in Mahallat City (Markazi province, Iran) were visited, and the CR of diamond circular saws was recorded on six different travertine stones. Next, the stone block samples were collected from the quarries for laboratory tests. Stones’ porosity (n), uniaxial compressive strength (UCS), and Schmidt hammer hardness (SH) were determined in the laboratory as their physico-mechanical characteristics. Correlation relationships of CR with physico-mechanical characteristics were evaluated using simple and multiple regression analyses, and estimator models were developed. Results showed that multiple regression models are more reliable than simple regression for estimating the stones’ CR. The validity of the developed multiple regression models was verified with the published data of one researcher. The findings indicated that these models are accurate enough for estimating the CR of stones. Consequently, the multiple regression models provide practical advantages for estimating the CR and save time and cost during the planning and design of the stone processing factories.