Potential Application of Pin-to-Liquid Dielectric Barrier Discharge Structure in Decomposing Aqueous Phosphorus Compounds for Monitoring Water Quality

Here, we proposed a pin-to-liquid dielectric barrier discharge (DBD) structure that used a water-containing vessel body as a dielectric barrier for the stable and effective treatment of aqueous solutions in an open atmosphere. To obtain an intense pin-to-liquid alternating current discharge using a dielectric barrier, discharge characteristics, including the area and shape of a ground-plate-type electrode, were investigated after filling the vessel with equivalent amounts of water. Consequently, as the area of the ground electrode increased, the discharge current became stronger, and its timing became faster. Moreover, we proposed that the pin-to-liquid DBD reactor could be used to decompose phosphorus compounds in water in the form of phosphate as a promising pretreatment method for monitoring total phosphorus in water. The decomposition of phosphorus compounds using the pin-to-liquid DBD reactor demonstrated excellent performance—comparable to the thermochemical pretreatment method—which could be a standard pretreatment method for decomposing phosphorus compounds in water.

Method of Preparation for Restoration of Worn Nitrided Journals of Crankshafts

The internal combustion engine is the most expensive component of a car, which determines the reliability and efficiency of its use. Studies show that one of the most common reasons for the failure of KAMAZ diesel engines during operation is the underutilization of the crankshaft resource due to wear of parts and couplings that limit its resource. An increase in the resource of crankshafts can be achieved by improving the technological processes of restoration and repair. Full utilization of the resource of KAMAZ nitrided crankshafts is possible by surfacing worn journals only after removing a nitrided layer up to 0.4 mm thick from the journals surface using specialized equipment for electrical discharge machining. Electrical discharge machining is based on the removal of material particles from the surface by an electric discharge pulse between electrodes immersed in a liquid dielectric, in the channel of which a high-temperature plasma is formed.

Systems Theory: Simulation Analysis of Space Charge Generation Mechanisms in Transformer Oil under High Electric Field

Simulation analysis plays an important role in Systems Theory nowadays. In order to reveal the mechanism of space charge injection and generation in the process of liquid dielectric breakdown, the discharge of transformer oil between needle-plane electrodes under high electric field is studied. Based on the 2-D hydrodynamic model and Poisson equation of electric field, the system simulation model of oil discharge by different charge generation mechanism is established, based on which the inception and propagation process of discharge is simulated by COMSOL. By system simulation, the temporal and spatial distribution of the electric field intensity, space charge density, electric potential and temperature of transformer oil is obtained and deeply analyzed. The simulation results prove that the space charge generated by metal field emission and ionic disassociation are neither of the major factor for streamer formation in transformer oil, while the Zener molecular ionization and impact ionization are the major factors. Our research improves the understanding of the inception, propagation and breakdown process for discharge in transformer oil, and also the ionization mechanism in the liquid dielectric