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.

To investigate the response of corn to combined application of chemical fertilizers with rhizobacteria plant growth promoting, an experiment was conducted in 2017 at Research farm of Agricultural and Natural Resources Campus of Tehran University, Karaj, Iran, in a randomized complete block design with four replications. Four nutritional treatments including T1 (control treatment without applying fertilizer), T2 (Just PGPRs), T3 (Use chemical fertilizers based on soil test) and T4 (T3 + PGPRs) were considered. According to the results, the highest total dry weight (3.9 kg/m2), crop growth rate (79.8 g.m-2.day-1), net assimilation rate (15.3 g.m-2.day-1) and grain yield (18.2 ton.ha-1) were observed in T4 treatment and T2 treatment produced the highest  leaf area index (5.3), leaf area duration (205.2) and specific leaf weight (78.5 g.m-2) . Also, the lowest value of all traits was observed in in T1 (control) treatment. The results showed that the presence of rhizobacteria plant growth promotioninduction in the corn nutrition program increased the growth and growth indices of the plant. Combined application of chemical fertilizers with rhizobacteria plant growth promoting resulted in the highest growth and final grain yield of corn.

Tomato leaf miner (Tuta absoluta) is one of the new and important pests of tomato in Iran and every year it reduces the yield and quality of the product in terms of marketability. Therefore, in order to use insecticides that are safer for the environment, consumers and natural enemies, in this study, the effect of spinosad, imidacloprid, indoxacarb and chlorantraniliprole insecticides on Tuta absoluta was evaluated under field conditions. This study was performed in a randomized complete block design with five treatments, one control, and three replications. The results of this study showed that the efficacy of chlorantraniliprole and spinosad was higher than indoxacarb and imidacloprid on the third, seventh, tenth and fourteenth days after spraying. Also, the effect of LC25 of each of the mentioned insecticides on the parasitism rate of tomato leaf miner moth eggs by two species of parasitoid wasps T. brassicae and Trichogramma evanescens was evaluated under laboratory conditions. The rate of reduction of parasitism in spinsad, imidacloprid, indoxacarb and chlorantraniliprole treatments for T. brassicae was 23. 73, 18. 31, 14. 58 and 9. 37%, respectively, and for T. evanescens 24. 02, 18. 65, 13. 78, 9. 75% was determined. The results showed that chlorantraniliprole was less toxic compared to other compounds studied for parasitoid wasps and compared to other insecticides, the rate of parasitism of two species of Trichogramma was less affected. Hence, its use in integrated pest management programs of T. absoluta is recommended.