Quasiclassical calculation of spontaneous current in restricted geometries

Calculation of current and order parameter distribution in inhomogeneous superconductors is often based on a self-consistent solution of Eilenberger equations for quasiclassical Green's functions. Compared to the original Gorkov equations, the problem is much simplified due to the fact that the values of Green's functions at a given point are connected to the bulk ones at infinity (boundary values) by ``dragging'' along the classical trajectories of quasiparticles. In finite size systems, where classical trajectories undergo multiple reflections from surfaces and interfaces, the usefulness of the approach is no longer obvious, since there is no simple criterion to determine what boundary value a trajectory corresponds to, and whether it reaches infinity at all. Here, we demonstrate the modification of the approach based on the Schophol-Maki transformation, which provides the basis for stable numerical calculations in 2D. We apply it to two examples: generation of spontaneous currents and magnetic moments in isolated islands of d-wave superconductor with subdominant order-parameters s and d_{xy}, and in a grain boundary junction between two arbitrarily oriented d-wave superconductors. Both examples are relevant to the discussion of time-reversal symmetry breaking in unconventional superconductors, as well as for application in quantum computing.Comment: 6 pages, Submitted for publication in the proceedings of MS+S2002 conference, Japa

Consumer Perceptions of Apparel Fit Satisfaction and Sizing Based on 3D Body Scanning and Block Garment Assessment

Sizing and fit in ready-to-wear apparel causes issues for retailers and consumers alike. Retailers must strive to better understand their consumers\u27 perceptions of themselves in order to help them purchase properly fitting clothing. If a manufacturer is able to improve their sizing system to provide a better fit for more body sizes, they may be able to help reduce returns and markdowns, as well as boost customer satisfaction and potentially increase sales. A major apparel retailer is working on improving the fit of their clothing in order to better meet the needs of their customers. A key objective of this study was to evaluate the fit of the major retailer\u27s standard block garments by assessing customer satisfaction, and to determine how accurately consumers comprehend their body size by utilizing body scanning technology. Consumer perceptions and preferences with regard to this major retailer\u27s clothing are central to the study

Filtragem adaptativa para a estimação da freqüência em sistemas elétricos de potência

Esta pesquisa apresenta um método para a estimação da freqüência em sistemas elétricos de potência utilizando filtros adaptativos baseados no método dos mínimos quadrados (MMQ). A análise do sistema de potência é realizada através da conversão das tensões trifásicas em um sinal complexo pela aplicação da transformada α β, sendo este direcionado ao algoritmo de filtragem adaptativa. As simulações computacionais, assim como a modelagem dos equipamentos, foram realizadas utilizando-se do software ATP (Alternative Transients Program). Este teve por objetivo, gerar dados das mais diversas e distintas situações para a verificação e análise da metodologia proposta, em comparação a resultados obtidos de um determinado relé comercial, habilitado à supervisão da freqüência do sistema.This research presents a method for frequency estimation in power system using adaptive filter based on the Least Mean Square algorithm (LMS). In power system analysis, the three-phase voltages are converted to a complex signal with the application of α β-transform whose complex form was submitted to the algorithm of adaptive filtering. The computational simulations were accomplished using the software ATP. This utilization had as objective to generate data for the most severe and different situations for the verification and analysis of the proposed methodology. The results were to those of a commercial relay for validation, showing the advantages of the new method.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Distance protection algorithm for multiterminal HVDC systems using the Hilbert–Huang transform

Multiterminal high-voltage direct current (HVDC) systems still need advances in terms of protection in order to improve their reliability. In this context, the distance protection can play a major role by adding selectivity to the existing DC fault detection algorithms. Hence, the present work proposes a non-unit DC distance protection algorithm that uses the frequency of the DC voltage transient oscillation to estimate the distance of the fault. The DC voltage transient frequency is extracted using the Hilbert–Huang transform and compared with a pre-defined frequency/distance curve. The technique was evaluated by simulating faults in a four-terminal symmetric monopole multiterminal HVDC system. In the simulation environment the algorithm was fully selective for faults within the first protection zone and had a correct operation rate of 94% or more for faults located in the second protection zone. To further validate the presented technique, the proposed algorithm was embedded in a digital signal controller, running in real-time. In all performed tests in hardware, the faults were correctly detected and identified as being internal or external. The results indicate that the proposed algorithm could be used in real-world applications, in conjunction with fault detection techniques, adding selectivity to multiterminal DC protection schemes

Quasiclassical calculation of spontaneous current in restricted geometries

Calculation of current and order parameter distribution in inhomogeneous superconductors is often based on a self-consistent solution of Eilenberger equations for quasiclassical Green's functions. Compared to the original Gorkov equations, the problem is much simplified due to the fact that the values of Green's functions at a given point are connected to the bulk ones at infinity (boundary values) by ``dragging'' along the classical trajectories of quasiparticles. In finite size systems, where classical trajectories undergo multiple reflections from surfaces and interfaces, the usefulness of the approach is no longer obvious, since there is no simple criterion to determine what boundary value a trajectory corresponds to, and whether it reaches infinity at all. Here, we demonstrate the modification of the approach based on the Schophol-Maki transformation, which provides the basis for stable numerical calculations in 2D. We apply it to two examples: generation of spontaneous currents and magnetic moments in isolated islands of d-wave superconductor with subdominant order-parameters s and d_{xy}, and in a grain boundary junction between two arbitrarily oriented d-wave superconductors. Both examples are relevant to the discussion of time-reversal symmetry breaking in unconventional superconductors, as well as for application in quantum computing