Asymmetric Little–Parks oscillations in full shell double nanowires

Little–Parks oscillations of a hollow superconducting cylinder are of interest for flux-driven topological superconductivity in single Rashba nanowires. The oscillations are typically symmetric in the orientation of the applied magnetic flux. Using double InAs nanowires coated by an epitaxial superconducting Al shell which, despite the non-centro-symmetric geometry, behaves effectively as one hollow cylinder, we demonstrate that a small misalignment of the applied parallel field with respect to the axis of the nanowires can produce field-asymmetric Little–Parks oscillations. These are revealed by the simultaneous application of a magnetic field perpendicular to the misaligned parallel field direction. The asymmetry occurs in both the destructive regime, in which superconductivity is destroyed for half-integer quanta of flux through the shell, and in the non-destructive regime, where superconductivity is depressed but not fully destroyed at these flux values.

Estimating the Reattachment Length by Realizing a Comparison between URANS k-Omega SST and LES WALE Models on a Symmetric Geometry

In this study, a water reattachment length was calculated by adopting two different models. The first was based on Unsteady Reynolds-Averaged Navier–Stokes (URANS) k-omega with Shear Stress Transport (SST); the second was a Large Eddy Simulation (LES) with Wall-Adapting Local Eddy-Viscosity (WALE). Both models used the same mesh and were checked with Taylor length-scale analysis. After the analysis, the mesh had 11,040,000 hexahedral cells. The geometry was a symmetrical expansion–contraction tube with a 4.28 expansion ratio that created mechanical energy losses, which were taken into account. Moreover, the reattachment length was estimated by analyzing the speed values; the change of speed value from negative to positive was used as the criterion to recognize the reattachment point.

A Low Profile Asterick-Shaped Polarization Free Metamaterial-Inspired Absorber for Penta-Band Characteristics

A penta-band absorber is proposed and developed exhibiting ultra thin and polarization insensitive behavior. It has been designed to be operated in S, C and Ku bands with absorptions peaks at more than 95%. Proposed absorber is processed on a FR4 Glass Epoxy laminate with equivalent electrical thickness of 0.0108 λ0 where λ0 is the wavelength corresponding to the lowest frequency of operation. This confirms the ultra-thin nature of the structure. The absorption pattern of the proposed structure has been characterized under normal and oblique incidence followed by their experimental verification. Presented results demonstrate highly polarization-independent behavior of the proposed absorber due to its symmetric geometry. Also, the electromagnetic field distributions have been studied to acquire better insight of the absorption mechanism corresponding to distinct elements presented in the structure. Then the suggested structure is characterized in terms of its behavior as metamaterial, which ensures the miniaturization. The proposed absorber is suitable to be used in applications like radar cross section reduction, stealth technology, radio frequency identification and electromagnetic compatibility.

Progressive Collapse of a Single Layer Schwedler Dome

Large span domes have always drawn architects’ and engineers’ interest as they provide as easy method of roofing large areas with architectural beauty. Single layer Schwedler Dome composed of Circular Hot Hollow Frame (CHHF) is investigated to understand the effects of individual member removal to the behaviour and stability of single layer dome. The major issues of the structural system are related to its instability phenomena whereby it is vulnerable to snap through buckling. The failure of space structure such as Sultan Zainal Abidin Stadium and Bucharest Dome clearly show an understanding of such failure and the behaviour of the space structure is important to develop a safer structure especially in the future. This study deals with a single layer dome having a diameter of 52 m and the span to depth ratio of ½. The loads subjected on the nodes of the structure consists of dead, live and wind loads and assumed to be 1kN each. Due to the symmetric geometry of the dome, the removals were done on the quarter section of the dome only assumed that the loads distribution patterns are similar for each section. This study required 210 members’ removals and the result obtained has been analysed thoroughly. In order to achieve the objectives of the research, computer programming such as FORMIAN, AutoCAD and SAP2000 V18 have been used to generate the geometry of the dome and afterwards analysed the stability of the structure. The numerical technique is based on redistribution of internal loadings due to member’s failure. Critical members are determined by analyzing the Demand Capacity Ratio (DCR) value of each member and identifying the number of overstressed neighboring members. When the internal load of a neighboring member exceeds its loading capacity, the member becomes overstressed and fails which may lead to major collapse of the entire structure. The value of the DCR and the numbers of overstressed members existed in the structure after the removals show the criticality of the section. As a conclusion, this critical area must be considered during analysis, design and construction stage of the dome.

Proving Triptycene Homoconjugation with the Same Chromophore but Different Connectivity to the Core

Homoconjugation is a phenomenon discussed for various π-systems where classical conjugation is broken by e.g. methylene units but still a stabilization by electronic communication exists. In this respect, triptycene with its rigid C3 symmetric geometry is an ideal scaffold to study this phenomenon. Although several studies based on triptycene strengthen the hypothesis of homoconjugation, in all described cases the electronic communication through space relies on different π-blades. Here, two triptycenes are presented having the exact same π-extended chromophore, but differently annulated to the bicyclic core. Both compounds were investigated by spectroscopic as well as computational means and compared with the corresponding model compound, elucidating the influence of the attachment site to the triptycene core on potential homoconjugation.

A Generic Embedding Class-I Model via Karmarkar Condition in f ℛ , T Gravity

In the present work, we investigate the existence of compact star model in the background of f ℛ , T gravity theory, where ℛ represents the Ricci scalar and T refers to the energy-momentum tensor trace. Here, we use Karmarkar condition for the interior stellar setup so that a complete and precise model following the embedding class-I strategy can be obtained. For this purpose, we assume anisotropic matter contents along with static and spherically symmetric geometry of compact star. As Karmarkar embedding condition yields a relationship of metric potentials, therefore we assume a suitable form for one of the metric components as e ϕ = a r 2 + b n − 1 r n + 1 , where a and b represent constants and n is a free parameter, and evaluate the other. We approximate the values of physical parameters like a , A , and B by utilizing the known values of mass and radius for the compact star Vela X-1. The validity of the acquired model is then explored for different values of coupling parameter λ graphically. It is found that the resulting solution is physically interesting and well-behaved.

MULTIBAND METAMATERIAL ABSORBER IN A RING STRUCTURE BASE ON HIGH-ORDER MAGNETIC RESONANCE

We proposed a multiband metamaterial absorber(MMA) based on high-order magnetic resonance using ring-shaped structures. This MMA is not only simple with highly symmetric geometry but also effectively absorptive with multi-band and down- scalability. It was found that the absorption occurred at some specific frequencies, which are three times and five times higher than that of common structures, originates from the magnetic resonances. In particular, the obtained results can be theoretically explained by using the LC circuit model. In addition, by scaling down the unit-cell size, the third- and fifth-order magnetic resonances are created at the THz frequencies. The presence of multiple absorption peaks opens the possibility for MMAs working from the GHz to the THz band.We proposed a multiband metamaterial absorber(MMA) based on high-order magnetic resonance using ring-shaped structures. This MMA is not only simple with highly symmetric geometry but also effectively absorptive with multi-band and down- scalability. It was found that the absorption occurred at some specific frequencies, which are three times and five times higher than that of common structures, originates from the magnetic resonances. In particular, the obtained results can be theoretically explained by using the LC circuit model. In addition, by scaling down the unit-cell size, the third- and fifth-order magnetic resonances are created at the THz frequencies. The presence of multiple absorption peaks opens the possibility for MMAs working from the GHz to the THz band.

PiCOPIC: 2.5-D PARTICLE-IN-CELL CODE, OPTIMIZED FOR SIMULATION OF BEAM-PLASMA INTERACTIONS

Original code optimized forsimulation of interactions between plasma and charged particles beams and bunches, based on particle in cell method described. The code is electromagnetic and fully relativistic with 2.5D axial symmetric geometry. Binary coulomb particle collisions are taken into account. The code is fully parallelized and designed for computer systems with shared memory. Ability to extend supported platforms to systems with distributed memory (like computer clusters or grids) is embedded into code architecture.