A Response Surface Methodology to Optimize Multiple Discharge Step Parameters for Sinking Electrical Discharge Machining

Conventional die-sinking electrical discharge machining (EDM) employs a single electrode operating under constant discharge conditions. We explored a two-electrode scenario, in which roughing and finishing were coupled. We developed a multiple discharge step (MDS) method that uses three discharge depths. The discharge current is highest in step 1 and lowest in step 3. Response surface methodology (RSM) was employed to optimize the discharge conditions. Experimentally, the MDS method combined with RSM decreased electrode edge wear and surface roughness compared to the conventional method, with no increase in the average discharge current.

Influence of the Condition of the Exposed Electrode Edge in the SDBD on the Discharge Operation Mode in Argon

The paper is devoted to the phenomenological study of the operating modes of a surface barrier discharge in argon in the case of treated by the discharge and new aluminum and copper electrodes. It is shown that without preliminary treating of the edges of the electrodes in the case of copper and aluminum electrodes, the discharge has a different spatial structure determined by the self-organization of the DBD. After erosion cleaning of the electrode edges, the identical operating modes are established. Such effects confirm the former assumption that the key factor determining the mode of the discharge operation for various electrode materials is the surface charge built on the oxides deposited on the edge. The different dynamics of oxides in the case of copper and aluminum electrodes is determined by the resistance of the oxides of these metals to sputtering, which is indirectly confirmed by the estimation of the binding energy for these materials.

Stochastic forcing of the 2D boundary layer by DBD plasma actuator

The paper describes the results of the parametric study of the broadband velocity pulsations, induced by DBD plasma actuator in 2D subsonic boundary layer. The presented data include the analysis of the disturbance growth at various pressure gradients. It is assumed that the broadband pulsations are composed of the elementary disturbances, induced by an individual microdischarges, wandering along the electrode edge. These disturbances have a streak-like structure in a near field, and evolve into a fan of packets of Tollmien-Schliechting waves as one moves downstream. The streamwise length, needed for transition to modal behavior, depends on the stability properties of the boundary layer.

Gas sensors based on dielectrophoresis of graphene, and graphene oxide, and reduced graphene oxide A Review

Dielectrophoresis (DEP) is a label-free, accurate, fast, and low-cost diagnostic technique that uses the principles of polarization and the motion of bioparticles in applied electric fields. DEP occurs when uncharged particles in the solution are subject to a spatially non-uniform alternating-current (AC) electric field, resulting in the motion of particles by creating a polarizability gradient between the particles and the suspending medium. The movement of particles in DEP is based on the difference in polarizability between the particles and the surrounding medium. If the particles move toward the electrode edge, the region of high electric field gradient, the response is called positive DEP (p-DEP). At the same time, if the particles move away from the electrode edge, the response is called negative DEP (n-DEP). This phenomenon provides a powerful and versatile tool for the non-destructive manipulation of nanoscale materials, allowing for the control of the resistance and the type of the assembly. This technique has been proven to be beneficial in various fields, including environmental research, polymer research, sensors, biosensors, microfluidics, medicine, and diagnostics. This paper reviews the fundamentals of DEP and its specific application in the incorporation of graphene, graphene oxide(GO), and reduced graphene oxide(RGO), enabling the assembly of individual two-dimensional nanostructures at predefined locations in microdevices for gas sensor applications. The review provides an essential framework for parallel fabrication approaches of graphene-based devices.

Design of a Schottky Metal-Brim Structure to Optimize 180–220 GHz Broadband Frequency Doubler MMIC

The present work proposes a 180–225 GHz broadband frequency doubler monolithic microwave integrated circuit (MMIC) based on a novel Schottky barrier diode (SBD) terminal structure denoted as a Schottky metal-brim (SMB). Compared with an MMIC adopting the conventional SBD terminal structure, preliminary measurements show that the maximum output power of the MMIC adopting the SMB structure increases from 0.216 mW at 206 GHz to 0.914 mW at 208 GHz. Analysis of the nonlinear current–voltage and capacitance–voltage characteristics of the two terminal structures based on an extended one-dimensional drift-diffusion model, indicates that the SMB structure provides significantly better conversion efficiency than the conventional SBD structure by eliminating the accumulation of charge and additional current paths near the Schottky electrode edge. It provides a feasible scheme for the optimization of MMIC applications requiring high power and high efficiency.