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There has been considerable interest in non-thermal discharges over the past decade due to the increased number of industrial applications. The properties of discharges in electronegative gases are most frequently used for technological applications. For the improvement of performance in these applications, it is necessary to understand discharge dynamics experimentally and numerically. In this paper, a Monte Carlo simulation is carried out in sulfur hexafluoride (SF₆) in uniform electric fields. The streamer propagation, electron, positive and negative ion distributions and space charge fields are studied in detail as time increases.

The corona discharge commonly occurs in many engineering devices and processes. Their application is still largely based on empirical knowledge; accordingly it is very important to predict the physical properties of corona discharge by the appropriate numerical method. To control corona discharge properly by understanding of corona discharge properties at different discharge stages, time-varying characteristics of discharge which are resulted from electron collision with the gas molecules should be investigated. A numerical study of a corona discharge in nitrogen in a point to plane geometry is presented. It is obtained by Monte Carlo method and concerns space-time evolution of electron and ion densities as well as electric field distributions along the discharge axis.

Modern experiments in hadronic physics require excellent detection and tracking capabilities in very high flux environment. Probing the quark and gluon content of the nucleon indeed necessitates semi-inclusive or exclusive reactions with very small cross-sections. Micromegas detectors have therefore been rapidly identified as natural candidates to equip the hottest region of the COMPASS spectrometer at CERN. Benefitting from several years of smooth operation at COMPASS, the Micromegas have been proposed to equip the future central tracker of the CLAS12 experiment at the Jefferson Laboratory. This project triggered an important R&D on the bulk and resistive technologies and inspired several projects involving cylindrical trackers. This paper focuses on the design and performance of the COMPASS and CLAS12 Micromegas, and reviews the R&D made on the discharge reduction in large hadron fluxes.

It is known that the press formability and the elongation of laser textured sheet are improved, and the service life of textured roll is longer than that of the un-textured roll due to hardening of the treated surface. One of the goals to develop high repetitive rate YAG laser-induced discharge texturing (LIDT) is to get deeper hardening zone. By observing and measuring cross-section of LIDT spots in different discharge conditions, it is found that the single-crater, which is formed by the discharge conditions of anode, which is covered by an oil film and with rectangular current waveform, has the most depth of heat affected zone (HAZ) comparing with other crater shapes when discharge energy is the same. The depth of HAZ is mainly depends on pulse duration when the discharge spot is single-crater. The results are analyzed.

Ultrasonic frequency vibration coupled micro-wire electrical discharge machining (UFV-$\mu$ WEDM) has received enormous consideration due to its zero-tolerance machining. Nickel chromium (Ni–Cr) space alloys are a natural choice within the aerospace industry, which are exposed to high temperatures and high pressure, such as turbine seals and exhaust liners. This study reveals the impact of the UFV-$\mu$ WEDM influencing machining parameters like ultrasonic frequency vibration (UFV), servo voltage ($V_S$), time on ($T_{\mathrm{\text{on}}}$), cutting angle ($A_C$), time off ($T_{\mathrm{\text{off}}}$), and current (I) on the Ni–Cr space alloy in terms of minimum surface undulation (Ra) with maximum material removal rate ($M_{\mathrm{\text{RR}}}$). The cutting trials are carried out by central composite design (CCD). Analysis of variance (ANOVA) is used to find out the proportionate contribution of several factors, and it discloses that $V_S$ was the significant parameter impacting Ra (64.57%) and $M_{\mathrm{\text{RR}}}$ (61.86%). The performance sequence of significant influencing parameters is $V_S>T_{\mathrm{\text{off}}}>A_C>T_{\mathrm{\text{on}}}>I$. According to desirability analysis (DA), optimum parameters for numerous solutions are $T_{\mathrm{\text{on}}}=8$$\mu$s, $V_S=50$V, $T_{\mathrm{\text{off}}}=14$$\mu$s, $I=3$A, and $A_C=30^{\circ }$. The optimum conditions lead to the highest $M_{\mathrm{\text{RR}}}$ (5.72mm³/min) and the lowest Ra (3.42$\mu$m). Scanning electron, 3D topography, and atomic force microscope images are used to analyze the machined surface.

The controlling method for high-voltage pulse form or pulse parameter is extremely important in high speed switching technique. Function generation can repeatedly make various forms and widths of pulse waves such as low-voltage sine wave, square wave, and sawtooth wave. Waveform control is not easy when voltage exceeds a certain amount of kVs. Pulse forming network (PFN) or pulse forming line (PFL) has been used so far along with trigger gap, rail gap, semiconductor switch, ignitron, cyratron, and autocompression switch, which are used as switching device. For PFN, multistep LC circuit is introduced to widen the pulse width, and for PFL, a method to lengthen the charging line is adopted. These methods are difficult to control because a large number of devices are used, and the devices are getting bigger in terms of size. In order to compensate this weakness, the researchers of this study made self-stimulating pulse forms with various pulse widths by actively engrafting the low-voltage two-step or four-step circuits with the AVR one-chip microprocessor technology, which is widely used for two-step or four-step electric network recently with low price.

Surface velocimetry has been steadily increasing interest and research on its applicability to stationary discharge measurement due to its measurement efficiency and economy. However, it has not yet been widely used due to some uncertainties in the measurement of surface velocity. The first is the uncertainty of the relation between the surface and mean velocity, and the others is for wind effect on surface velocity.

In the case of measurement of water surface velocity, the direction and height of the wave on water surface can be changed by wind, which may cause an error in the surface velocity value. For higher velocity in flood flow, the influence of the wind speed is negligible on surface velocity, but as the velocity decreases, the influence of the wind effect on the surface velocity increases relatively.

In this study, in order to analyze the effect of wind speed and direction on the surface velocity under constant flow conditions when measuring discharge using surface velocity meter, wind direction anemometer(150WX of AIRMAR Co.) was installed with radar surface velocimetry(RQ-30 of SOMMER co.) in an test river.

From the results, speed and direction of wind was found to affect the measured surface velocity in low flow condition. Wind speeds of 2.5 m/s or more caused fluctuations of 20.0~71.4 % of the surface velocity depending on the wind direction, while the effect was not significant as 2.9~8.6 % at less than 1 m/s of wind speed. Therefore, for calculating the discharge by measuring the surface velocity, the effect of wind speed and direction should be considered, especially in low flow conditions where the influence of wind is relatively large.

A 26-year-old woman complains of excessive vaginal discharge for two weeks.

• What is the origin of physiological vaginal discharge and how is it distinguished from pathological discharge?
• What conditions may manifest by vaginal discharge?
• When and what laboratory investigations are indicated for vaginal discharge?

The probability of a discharge being pathological increases when other features are present, such as discoloration in the discharge, presence of an odor and/or vulvo-vaginal itch, blood staining in the discharge, post-coital bleeding, and recent onset of dyspareunia.