Numerical Study of Pulsed Dielectric Barrier Discharge at Atmospheric Pressure Under the Needle-Plate Electrode Configuration

In this paper, we study the characteristics of atmospheric-pressure pulsed dielectric barrier discharge （DBD） under the needle-plate electrode configuration using a one-dimensional self-consistent fluid model. The results show that, the DBDs driven by positive pulse, negative pulse and bipolar pulse possess different behaviors. Moreover, the two discharges appearing at the rising and the falling phases of per voltage pulse also have different discharge regimes. For the case of the positive pulse, the breakdown field is much lower than that of the negative pulse, and its propagation characteristic is different from the negative pulse DBD. When the DBD is driven by a bipolar pulse voltage, there exists the interaction between the positive and negative pulses, resulting in the decrease of the breakdown field of the negative pulse DBD and causing the change of the discharge behaviors. In addition, the effects of the discharge parameters on the behaviors of pulsed DBD in the needle-plate electrode configuration are also studied.

Time development of surface enhanced Raman intensities of the adsorbed pyrazine molecules on the silver electrode as the applied voltage varies

In this work,the time development of surface enhanced Raman intensities of the vibrational modes involving the ring skeleton and the C—H motions of the pyrazine molecule as the applied voltage on the silver electrode is shifted between -0.2 V and -0.5 V (vs.saturated calomel electrode)is reported.The observation shows that there are two processes of enhancement involved during this shift of applied voltage.One is vibrational mode dependent while the other is not.The detailed behavior of these two processes of enhancement is discussed along with the retarded response of the Helmholtz double layer structure to the change of the applied voltage on the electrode.

An EEG Acquisition System with Dynamic DC Suppression

A three op-amps instrumentation amplifier(I.A) is one of the most important segments in the electroencephalographic(EEG) acquisition system, which is used to suppress the interference of the common mode noise. However, electrode and op-amps offset voltages could saturate the I.A, so the ability of noise suppression for the I.A might be limited. To compensate for the electrode and op-amps offset voltages and improve the property of the I.A, the optical-isolated technology was used in the present study.This paper described the theory of DC suppression and employed the simulation software(i.e. Multisim10.0.) to demonstrate the constant<urrent source of the optical-isolated device comprised of general-purpose optocouplers.Using this technology we designed and tested an EEG acquisition system.During the test,a constant current was generated by the optocoupler(the MOTOROLA 4N35)when DC offset voltages from 0 to 15 mV were imposed on the input signal in the EEG acquisition system and the value of load resistance in the optical--isolated device was from 3 k to 15 kom.We also found that the IA with the gain of 857 could effectively reject a DC input rangeof±15mV.And An EEG signal is obtained by the EEG acquisition system,and a CMRR of 104.5 dB was achieved without trimmings.