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Dielectric barrier discharge (DBD) has received more and more attention due to its wide application in many industrial applications, such as medical treatment, materials processing, and environment protection. The coupling of airflow and discharge is an important issue, such as the influence of flow velocities on discharge characteristics and the influence of discharge on airflow characteristics have been extensively studied. In this paper, the airflow of the periodic Karman vortex is constructed and the influence of the airflow on the discharge pattern is studied. Through measuring the discharge signal and relative light intensity under the Karman vortex, it is found that the discharges in the vortex areas are more vulnerable to breakdown and the relative light intensities of the discharges are stronger. In the front of the cylindrical section, the discharge pattern shows the discharge filament following the incoming flow direction. At the rear of the cylindrical section, the discharge pattern is presented as curved discharge wire configuring two rows of vortexes. The dynamic characteristics show that two rows of vortexes are generated and separated alternately, and each row of the vortex is also regularly generated and separated. The movement law of the discharge patterns is basically the same as the Karman vortex simulation. The variation characteristics of the airflow can be basically reflected in the discharge patterns. The dynamic characteristics of dielectric barrier discharge patterns are related to the changes of the spatial domains of the Karman vortex constructed in this paper.

Ionic wind could convert electrical energy to kinetic energy with no need rotating parts, which has attracted wide attention in the field of propulsion, the improvement method of ionic wind thruster performance has been a potential research direction. In this paper, an auxiliary ring electrode structure is designed to adjust the ionization and acceleration process of particles. The reduced electric field and discharge characteristics are investigated to demonstrate the influence of ring electrode to the energy and spatial distribution of particles. Besides, the ionic wind thrust parameters such as ionic wind velocity profiles, thruster and electrical-to-kinetic energy conversion efficiency are further studied to illustrate the improvement effect of auxiliary ring electrode on ionic wind characteristics. These phenomena are investigated by considering the ionization and acceleration process of particles under the effect of auxiliary ring electrode. The results illustrate that the arrangement of auxiliary ring electrode would be a method to improve the ionic wind thrust performance.

In order to solve the problems of retention time delay caused by the direct prediction for users' off-grid state and insufficient information mining caused by the too rough granularity of the monthly statistical features in the past, this paper presents the approach that applies serialized data analysis method to users' records serialized with Day as its granularity. Users' data would be sampled and analyzed by using the sliding windows. Then the churn incline among the users would be predicted in advance by collecting and sorting out their antecedent behavior occurring before their churn. The related experiments were conducted with real mobile communication records of social users and reached 98.22% recall and 0.98 F1(F1-measure) when it reached its highest level. Along with comparing with the traditional modeling which takes month as the granularity for its statistical item, the timeliness and predicting competency of the method presented in this article has been verified both theoretically and by the result of the test.

Lots of research have been carried out since Trichel pulse was presented in 19341,2. In order to obtain some stochastic properties of Trichel pulse in wire-plate negative corona discharge, statistical method is used in this paper to analyze three characteristic parameters of Trichel pulse, which are amplitude A, rising time t r , half-falling time t f .

In this work, effect of dielectric temperature on atmospheric pressure nonequilibrium plasma jets (APNPJs) with different dielectric materials has been investigated1–2. In our experiments, a single-electrode plasma generation equipped with an AC power supply is applied. Two materials, 95% alumina cerami c and quartz are adopted as dielectric tube. To distinguish the APNPJ status from the argon flow rate, the three modes, laminar, transition and turbulent, are separated.

As an emerging source, atmospheric pressure nonthermal plasma jets (APNPJs) have held remarkable promise owing to its wide applications1. At low pressure (∼0.1 Pa), magnetic field i s always introduced into plasmas to affect the discharge current2. However, little works have been reported on the interaction between magnetic field and atmospheric pressure plasmas. In this work, effect of magnetic field on the propagation of Ar APNPJs is investigated through a single-electrode configuration by use of AC power. In order to avoid the interference of the electric field by the permanent magnet, a same size iron is set i n the electric field to replace the permanent magnet when there's no magnetic field. We compare the electrical characteristic with/without iron and with/without magnetic field. As seen in Fig. 1, with the magnetic field, the discharge current is clearly increased, however, with and without the iron, the discharge current show slight difference. It is believed that the enhancement of ionization in the curved and lengthened electron path caused by Lorentz force is the main reason.

Plasma generated by discharge has wide applications, which require the formation of a large-volume discharge in atmospheric pressure. The key to an optimal application performance lies in how to generate stable and diffuse plasma especially in a large-volume and in high-speed airflows1. This paper presents our study of repetitive nanosecond volume discharge behaviors in high-speed airflows.

Plasma jet is one kind of atmospheric pressure discharge which has been studied extensively. The stable /unstable states of plasma jets have been demonstrated in previous studies1. And the plasma jet which can keep in stable stage is important for application. In this study, we are focus on the influence of grounding electrode for the stage of plasma jet.