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The influence of the cylindrical exposed electrode diameter on distribution and attenuation of the surface charge in surface dielectric barrier discharges is experimentally investigated using the Pockels effect of the Bi12SiO20 crystal. For the actuator with the smaller exposed electrode diameter, more positive charges accumulate closer to the exposed electrode after positive half periodic discharge, while the quantity of positive charges deposited on the surface in a discharge period at the same distance away from the exposed electrode is smaller. At the same time, the smaller the exposed electrode diameter is, the shorter decay time the positive charge filament needs. Combined with thrust generation of actuators, it can be indicated that a positive residual surface charge closer to the exposed electrode may play a more crucial role in the discharge and consequent thrust than one far away from the exposed electrode does. Also, the effect on the discharge of the positive residual surface charge may be greater than that of the negative residual surface charge. More explorations of the residual surface charge have been done by selectively enhancing the discharge of the actuator with a 10 μm exposed electrode using the pulse-AC dual power supply, drawing the same conclusions. [ABSTRACT FROM AUTHOR]

The surface charge distribution in a surface dielectric barrier discharge driven by repetitive pulse bias superimposed on AC voltage is measured using the Pockels effect of an electro-optic crystal. The impact of surface charge on surface-breakdown characteristics is investigated by varying the phase of the pulse superimposition. It is demonstrated that the surface charge accumulation varies at different superimposition phases depending on the potential difference between the two electrodes. The accumulated positive/negative surface charge will facilitate the following surface discharge when the AC voltage polarity changes. In addition, different spatiotemporal characteristics of the surface charge distribution are presented when changing the polarity of superimposed pulses. Positive surface discharges are usually easier to develop than negative surface discharges due to their lower breakdown voltage caused by the accumulation of negative surface charges near the edges of exposed electrodes. The decay of positive surface charge is dominated by neutralization of negative surface charge and negatively charged particles (free electrons and negative ions) from the volume above the dielectric. There are two decay modes of positive surface charge: exponential decay and linear decay. [ABSTRACT FROM AUTHOR]

Perilla is an important homologous plant, and it is also a high quality feed raw material. It is rich in nutrients, mainly crude protein, crude fiber and crude fat. The main compounds in Perilla include volatile oils, flavonoids, phenolic acids, terpenoids, anthocyanins and polysaccharides, with different component activities. Perilla has the functions of antiinflammatory, anti-bacterial, antioxidation, anti-tumor, anti-allergy and other pharmacological activities. The components of rosemary acid, luteolin, apigenin and caffeic acid in Perilla can be used as an animal feed additive, which can increase feed utilization, improve meat quality and lipid metabolism disorders, enhance gastrointestinal function and antioxidant capacity, and improve production performance. In the paper, the nutritional composition, pharmacological activity and application of Perilla in animal feed are reviewed in order to provide a reference for the rational application of Perilla in animal production. [ABSTRACT FROM AUTHOR]

This study explores the discharge uniformity at different cycles under different airflow velocities in nanosecond‐pulsed dielectric barrier discharge. Based on a proper choice of the airflow velocity and discharge parameters, diffuse discharges can be maintained at an air gap of 5–7 mm. At higher airflow velocities, the discharge may transition to a complex mode, in which the diffuse and filamentary regions are maintained simultaneously. When the discharge is operated at a higher frequency, higher voltage, or smaller gas gap, the area of diffuse discharge can be expanded to a certain extent. The discharge characteristics indicate that airflow lowers the gas temperature and modulates the preionization degree, which induces the generation of a diffuse discharge for a properly adjusted airflow velocity. [ABSTRACT FROM AUTHOR]

The time evolution of dielectric barrier discharge driven by nanosecond pulse high-voltage power is investigated by high-speed video analysis, electrical measurements and spectral diagnostics. It is found that the discharge mode generally goes through the evolution process of filamentary discharge → diffuse discharge → filamentary discharge with the increase in discharge cycle. The time-dependent changes in the standard deviation of image gray levels indicate that the discharge uniformity first improves and then deteriorates in this evolution process. The different pre-ionization density and modulated distribution of space charges and surface charges are considered to be the main reasons for the time evolution of discharge uniformity. In addition, the experiments under different frequencies and voltages show that the transition of the discharge mode is more likely to occur at higher frequency and higher voltage. Further measurement and calculation reveal that the discharge at high frequency and high voltage has the same characteristics, that is, high pre-ionization degree, thick filament diameter and short time lag. These characteristics usually lead to higher seed electron density, larger critical avalanche size and weaker lateral inhibition effect, which make the discharge mode transition more likely to occur. [ABSTRACT FROM AUTHOR]