<!-- *** Custom HTML *** -->We compared 9 × 9 arrays of bimetallic Ni(Nickel)-Pt(Platinum) nanoantennas for a classic and evolutive dipole configuration. We fabricated the nanoantennas by e-beam lithography and characterized them with a solar simulator to analyze the I − V curves. From these curves, a thermoelectric voltage dependence associated by classic and evolutive dipole configuration was observed. We show that the evolutive dipole nanoantennas (EDN) generate up to three times more voltage in contrast with the classic dipole nanoantenna (CDN). Indeed, the evolutive configuration is 1.3 times more efficient than its classical counterpart. The results are corroborated by absorbance of these nanoantennas in the 20 to 36 THz range, where EDN is 40% more efficient than CDN and 30% in the range of 36.1 to 90 THz. Moreover, the experimental results match the thermoelectric behavior obtained using numerical simulations. The EDN can be used in applications ranging from aerospace technology to energy harvesting, photodetector, and sensors, where high thermoelectric efficiency is needed.
We present an analogy between the one dimensional Poisson equation in inhomogeneous media and the Dirac equation in one space dimension with a Lorentz scalar potential for zero energy. We illustrate how the zero energy state in the Jackiw-Rebbi model can be implemented in a simple one dimensional electrostatic setting by using an inhomogeneous electric permittivity and an infinite charged sheet. Our approach provides a novel insight into the Jackiw-Rebbi zero energy state and provides a helpful way to visualize and teach this important quantum field theory model using basic electrostatics.
Understanding the phenomena that cause jet oscillations inside funnel-type thin-slab molds is essential for ensuring continuous liquid steel delivery, improving flow pattern control, and increasing plant productivity and the quality of the final product. This research aims to study the effect of the nozzle’s internal design on the fluid dynamics of the nozzle-mold system, focusing on suppressing vorticity generation below the nozzle’s tip. The optimized design of the nozzle forms the basis of the results obtained through numerical simulation. Mathematical modeling involves fundamental equations, the Reynolds Stress Model for turbulence, and the Multiphase Volume of Fluid model. The governing equations are discretized and solved using the implicit iterative-segregated method implemented in FLUENT®. The main results demonstrate the possibility of controlling jet oscillations even at high casting speeds and deep dives. The proposed modification in the internal geometry of the nozzle is considered capable of modifying the flow pattern inside the mold. The geometric changes correspond with 106% more elongation than the original nozzle; the change is considered 17% of an inverted trapezoidal shape. Furthermore, there was a 2.5 mm increase in the lower part of both ports to compensate for the inverted trapezoidal shape. The newly designed SEN successfully eliminated the issue of jet oscillations inside the mold by effectively preventing the intertwining of the flow. This improvement is a significant upgrade over the original design. At the microscale, a delicate force balance occurs at the tip of the nozzle’s internal bifurcation, which is influenced by fluctuating speeds and ferrostatic pressure. Disrupting this force balance leads to increased oscillations, causing variations in the mass flow rate from one port to another. Consequently, the proposed nozzle optimization design effectively controls microscale fluctuations above this zone in conjunction with changes in flow speed, jet oscillation, and metal–slag interface instability.
17 October 2019 in Microwave and Optical Technology Letters