Effects of Transverse Magnetic Field with Different Alternating Currents on Heat Flux Density Distributions of Plasma Arc
An external transverse-alternating magnetic field with sinusoidal and triangular alternating currents was applied to a combined plasma arc to create a plasma arc for expanding the cross section of arc column and flatting the distributions of arc temperature. Two mathematical models were developed to describe the heat flux density distributions of the combined plasma arc driven by a transverse-alternating magnetic field with sinusoidal and triangular alternating currents. The behavior of plasma arc under the external transverse-alternating magnetic field imposed perpendicular to the plasma current was discussed theoretically and experimentally by changing various parameters such as working gas flux, arc current, magnetic flux density including its wave form and the standoff from the nozzle to the workpiece. The analytical results show that it is feasible to adjust the shape and heat flux density of the combined plasma arc by the transverse- alternating magnetic field, which expands the region of combined plasma arc thermal treatment and uniforms the heat flux density upon the workpiece. Changing the waveform of the alternating current can also control the heat flux density distribution. As well as, calculated heat flux density distributions of combined plasma arc driven by the external transverse-alternating magnetic field show a good agreement with experimental data. The magnetic field with triangular alternating current can flat the heat flux density distribution on the anode rather than sinusoidal one. This approach to flat the heat flux density distribution on the anode surface will give an effective controllability to the combined plasma arc application.
Classical Mechanics: Applied Mechanics and Mechatronics
Preface.- List of Symbols.- 1. Dynamics in Mechatronic Systems.- 2. Equations of Motion of a Rigid Spherical Body.- 3. Theory of Gyroscopes.- 4. Dynamics and Control of a Gyroscope.- 5. Gyroscopic Control in Self-Guidance Systems of Flying Objects.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.