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Although in recent two decades, the concept of Dielectric Barrier Discharges (DBDs) have been developed in ozone production well, air pollution control, plasma screens and control of chemical, and biological and medical processes, employment of this concept for high voltage applications to improve insulation performance as an alternative to the pressurized gas-insulated systems (GIS) utilizing SF6, is still in research phase. In this paper, the enhancement of insulation performance using DBD and with increasing charge densities on the barrier surfaces in uniform electric filed has been statically modeled. This means that the dynamics of the development of space charges and the manner they sit on the barrier surfaces are ignored and only DBD concepts considering different amounts of surface charges on the barrier surfaces are evaluated. Also the influence of various parameters, such as permeability of the dielectric material, its thickness, and length of air gap, on the enhancement of insulation performance are evaluated. Then an algorithm for the formation of space charges, settling on the barrier surfaces and electric filed modification in the air gap for three types of voltage including DC, AC and lightning impulse, is simulated and evaluated using MATLAB. In this modeling, dielectrics are considered as non-insulating with some electrical conductivity.

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This paper deals with experimental measurements of the instantaneous ionic wind velocity induced by Dielectric barrier discharge (DBD) plasma actuator in quiescent air at atmospheric pressure. A parametric study has been performed in order to increase the velocity of the ionic wind induced by the DBD actuators. The electrical and mechanical characteristics of the plasma actuator have been studied under different conditions. The main objective of this work was to help to optimize the geometrical and electrical parameters to obtain more effective ionic wind for flow control. The time averaged velocity profiles of the ionic wind show that the position of the maximum velocity come near the surface by increasing the excitation frequency. Our results indicate that the DBD plasma actuators generate vortices at the same frequency of the excitation frequency of the applied high voltage. The power, of the vortices that are shed from the actuators, increases by increasing duty cycle percentage. Unlike other similar works in this field, this study has examined the behavior of unsteady plasma actuator.

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In flows with high Reynolds inside the U-shaped tubes separation phenomenon occurs in the curvature of tubes that causing pressure loss and in conditions associate with heat transfer causes undesirable increase surface temperature in that region. Due to reduced heat transfer rate from surface to fluid temperature increase occurs that in industrial applications in addition to reduce heat transfer causes damage to surface pipes. in the present study, elimination of the separation zone through body force created by plasma actuators and because it reduce the maximum temperature occurred in this region and changes the Peclet number is simulation in this region. For this purpose, the plasma actuators 5kV, 12kV and 19kV with square voltage function inside U-shaped tube in the three streams with Reynolds 3000, 4500 and 6000 have been placed to Influence of actuators on separation control and maximum temperature occurred at this point be investigated. Calculations with using of proposed model of Suzen with time-dependent numerical procedure has been done. And results during time performance of 0 to 50 have been reported. The results shows that maximum surface temperature that occurs in the region of separation in the presence of plasma actuator near this region has a significant reduction that is due to the elimination and change separation region.

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Dielectric barrier discharge (DBD) plasma actuators are one of the new devices for active flow control, which has received substantial attention during the last decade. The performance of the actuator is optimum when it induces the highest velocity per unit of power consumption. Since the induced velocity and the power consumption of the actuator depend on many different variables, finding the optimal set, which results in the best performance, is of immense importance. In this paper, in order to optimize the performance of these actuators, at first, by using full factorial design of experiments the effect of electrical variables (including voltage and frequency) and geometrical variables (including the gap between electrodes, dielectric thickness, and covered electrode width) on induced flow velocity and power consumption in steady actuation is experimentally investigated. Then, by using the multi-layer perceptron neural network, a model is created for the ratio of induced velocity to power consumption. The model is validated both statistically and experimentally. The results indicate that the coefficient of determination for training and test data is higher than 95 percent. Finally, the surrogate model is optimized by genetic algorithm and the optimal value of electrical and geometrical variables is determined. In order to validate the result, an actuator is designed based on the optimal set of variables and it’s ratio of velocity to power is measured to be
29.71 (m/s)/(kW/m). The difference of 3 percent between the measured and the predicted value demonstrates high accuracy and correctness of the proposed model and method.

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The aim of the present study was to investigate the possibility of the soy protein isolate-carboxy methylcellulose conjugate via non-thermal plasma. Therefore, a 1: 1 mixture of soy protein isolate and carboxymethylcellulose was treated with DBD plasma for 5, 10 and 15 min under the voltages of 16, 18, and 20 kV. Then, the solubility, Emulsifying activity and emulsion stability, the average particle size of the emulsion, the glycation degree, the Fourier transform infrared spectrum (FTIR), and the electrophoretic pattern of the resulting complexes were investigated. The results of electrophoresis, FTIR, and glycation degree proved the formation of soy protein isolate-carboxymethylcellulose conjugate after plasma treatment. The amount of conjugate formation depends on voltage and time of plasma treatment. The resulting conjugates had significant solubility and emulsifying activity compared to the mixture of these two compounds (p <0.05). The smallest droplet size of emulsion was observed in 18 kV treatment for 5 min, which has better stability over time compared to the mixture of soy protein-carboxymethyl cellulose. In general, it can be said that the non-thermal plasma process is able to rapidly form a protein-polysaccharide conjugate with a very good emulsifying ability.

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The present study aims to extract cellulose fibers from the walnut shell using dielectric barrier discharge (DBD) plasma pretreatment and to evaluate its properties. For this purpose, powdered walnut shells were exposed to 18 and 20 kV DBD plasma for 10 min in three stages. First, before sodium hydroxide alkaline treatment, next, before sodium chlorite bleaching treatment, and then, before both alkaline and bleaching treatments. The extraction efficiency, FTIR, XRD, thermal properties, FESEM and diameters of the cellulose fiber were evaluated. Based on the results, the extraction efficiency was significantly affected by applied voltage (p<0.05) and due to plasma destruction of glycosidic, the efficiency was reduced. The removal of peaks related to impurities from the walnut shell and the purity of all extracted cellulose was confirmed with FTIR. The results showed that applying DBD plasma during cellulose extraction did not affect its crystal structure, but the reduction of crystallization index was observed. Furthermore, the effect of plasma on the thermal-gravimetry of the samples was observed at temperatures below 100 ° C, and after the onset temperature of degradation, the behavior of the treated and untreated fibers until the final thermal decomposition was not significantly different. The microstructure of plasma-treated samples showed an increase in cellulose fiber's roughness and swelling, followed by the transformation of microfibrils to nanofibrils with a diameter of 80 nm at the higher voltage. In general, the results showed that applying 20 kV DBD plasma in both stages before the alkaline and delignification process is a more suitable treatment for extracting cellulose and producing cellulose nanofibers.