Intrinsic spin Hall effect in systems with striped spin-orbit coupling

The Rashba spin-orbit coupling arising from structure inversion asymmetry couples spin and momentum degrees of freedom providing a suitable (and very intensively investigated) environment for spintronic effects and devices. Here we show that in the presence of strong disorder, non-homogeneity in the spin-orbit coupling gives rise to a finite spin Hall conductivity in contrast with the corresponding case of a homogeneous linear spin-orbit coupling. In particular, we examine the inhomogeneity arising from a striped structure for a two-dimensional electron gas, affecting both density and Rashba spin-orbit coupling. We suggest that this situation can be realized at oxide interfaces with periodic top gating.Comment: 9 pages, 8 figure

DEVELOPMENT OF PREDICTIVE MODELS FOR QUALITY CONTROL OF GALA APPLES DURING DRYING

This thesis research project is aimed at setting up prediction models based on NIR spectroscopy, for quality control of organic apple wedges (Malus domestica B., var. Gala) during hot-air drying process (horizontal flow) up to 8 h. Hot-water and microwave blanching were both tested at 95°C for 5 min and 850 W for 45 sec, respectively, as pre-treatments to control the occurrence of enzymatic browning during drying. However, hot-water blanching had a negative impact on the appearance of the apple wedges, which were subjected to non-enzymatic discoloration (e.g. Maillard’s reaction). PLS regression showed good performances for the prediction of aw (RMSE = 0.03-0.04; R2 = 0.97-0.98), moisture (RMSE = 0.04-0.05; R2 = 0.97-0.98), SSC (RMSE = 4.54-4.99 °Brix; R2 = 0.96-0.97) and changes in chroma (RMSE = 2.31-2.75; R2 = 0.81-0.86) during drying. Also PLSDA classification showed very good metrics (total accuracy > 95%) in recognising 3-drying steps, both for control and microwave-treated samples. Features selection by iPLS and iPLSDA algorithms showed results better/equal than models based on full spectrum. For these results, the implementation of low-cost NIR sensors on drier device, seems feasible

3D Homogenized T-A Formulation for Modeling HTS Coils

The estimation of losses in high-temperature superconductors (HTS) is fundamental during the design of superconducting devices since losses can strongly influence the cooling system requirements and operating temperature. Typically, 2D finite element analysis is used to calculate AC losses in HTS, due to the lack of analytical solutions that can accurately represent complex operating conditions such as AC transport current and AC external applied magnetic field in coils. These 2D models are usually a representation of an infinitely long arrangement. Therefore, they cannot be used to analyze end effects and complex 3D configurations. In this publication, we use the T-A homogenization in 3D for the analysis of superconducting coils. This allows simulating complex geometries such as racetrack coils. We show that this approach has lower computation time than the currently available 3D homogenization of the H formulation. The approach is first validated against measurements and 2D axisymmetric solutions. Then, it is used to estimate losses and study the electromagnetic behavior of a racetrack coil

AC loss calculation in high-temperature superconductor wires and windings with analytical and numerical models: Influence of Jc_{c}(B) dependence

Too high loss levels can severely limit the efficiency and the safe operation of several high-temperature superconductor (HTS) AC applications. A reliable estimation of AC losses, which includes the observed field-dependence of the superconductor\u27s critical current density on the magnetic field, is therefore paramount. In this contribution, we use numerical simulations to evaluate the AC losses of HTS coated conductors in a variety of working scenarios: individual wires carrying AC transport current and/or subjected to AC magnetic fields, and wire assemblies like stacks and arrays carrying AC transport current. Numerical results are compared to the corresponding analytical models and to experimental results. This work presents some general guidelines regarding the extent to which the dependence of the critical current density J$_{c}$ on the magnetic flux density B modifies the AC loss characteristics with respect to a constant-J$_{c}$ model based on the superconductor\u27s self-field critical current