Wronskian formula for confluent second-order supersymmetric quantum mechanics

The confluent second-order supersymmetric quantum mechanics, for which the factorization energies tend to a single value, is studied. We show that the Wronskian formula remains valid if generalized eigenfunctions are taken as seed solutions. The confluent algorithm is used to generate SUSY partners of the Coulomb potential.Comment: 7 pages, 1 figure, to be published in Physics Letters

Second order SUSY transformations with `complex energies'

Second order supersymmetry transformations which involve a pair of complex conjugate factorization energies and lead to real non-singular potentials are analyzed. The generation of complex potentials with real spectra is also studied. The theory is applied to the free particle, one-soliton well and one-dimensional harmonic oscillator.Comment: 11 pages, 2 figures, submitted on 23 August 2002 to Phys. Lett.

New supersymmetric partners for the associated Lame potentials

We obtain exact solutions of the one-dimensional Schrodinger equation for some families of associated Lame potentials with arbitrary energy through a suitable ansatz, which may be appropriately extended for other such a families. The formalism of supersymmetric quantum mechanics is used to generate new exactly solvable potentials.Comment: 8 pages, 2 figures, submitted on 24 November 2004 to Phys. Lett.

Control hardware de una FPGA para el estudio de su comportamiento bajo radiación en entornos hostiles

En la actualidad, los sistemas embebidos han logrado un gran auge gracias a sus diferentes campos de aplicación y a sus bajos costos comparados con sistemas de cómputo tradicionales. Desde su invención en el año 1984, la gran capacidad de reconfiguración y adaptación que ofrecen las FPGA las hace muy atractivas en múltiples sectores, tales como el aeroespacial o el industrial. Sin embargo, los efectos de la radiación en estos dispositivos, cuyo comportamiento viene determinado por una memoria de configuración, pueden ser tan catastróficos que su uso en entornos de alta radiación debe venir acompañado por una serie de técnicas de protección, tanto a nivel tecnológico como de diseño. Por este motivo, y para realizar una posterior investigación sobre el comportamiento de un determinado circuito implementado en una FPGA en entornos hostiles y bajo las condiciones mencionadas, surge este trabajo. Para realizar las pruebas de inyección de fallos, bien a través de plataformas de emulación o de un sistema de aceleración de partículas, es necesario un sistema externo de control del circuito, en particular de los datos de entrada-salida y del reloj del mismo. Este sistema de generación de reloj, que se ha desarrollado en este trabajo, se ha integrado en un sistema global de inyección de errores que permite poner a prueba la vulnerabilidad de cualquier circuito frente a radiación real. En este trabajo se aborda el estudio de la transmisión de una señal de reloj de manera fiable entre dos FPGA a distancia moderada, mediante la implementación de diferentes técnicas, que permiten aumentar la inmunización al ruido impulsivo y la radiación electromagnética. Para alcanzar este propósito se han utilizado varias FPGA de las familias Artix 7 y Virtex 5 del fabricante Xilinx. Por último, se han obtenido y comparado resultados reales del envío de dicha señal a diferentes distancias y frecuencias

Renormalization of spin excitations and Kondo effect in open-shell nanographenes

We study spin excitations and the Kondo effect in open-shell nanographenes, motivated by recent scanning tunneling inelastic spectroscopy experiments. Specifically, we consider three systems: the triangulene, the extended triangulene with rocket shape, both with an S = 1 ground state, and a triangulene dimer with S = 0 on account of intermolecular exchange. We focus on the consequences of hybridization of the nanographene zero modes with a conducting substrate on the dI/dV line shapes associated with spin excitations. The partially filled nanographene zero modes coupled to the conduction electrons in the substrate constitute multiorbital Anderson impurity models that we solve in the one-crossing approximation, which treats the coupling to the substrate to infinite order. We find that the coupling to the substrate leads to (i) renormalization of the spin flip excitation energies of the bare molecule, (ii) broadening of the spectral features, and (iii) the emergence of zero bias Kondo peaks for the S = 1 ground states. The calculated substrate induced shift of the spin excitation energies is found to be significantly larger than their broadening, which implies that this effect has to be considered when comparing experimental results and theory.D.J. acknowledges funding by the Basque Government through grant “Grupos Consolidados UPV/EHU del Gobierno Vasco” (Grant No. IT1249-19). R.O. acknowledges financial support from Generalitat Valenciana and Fondo Social Europeo (Grant No. ACIF/2018/175). J.F.R. acknowledges financial support from Generalitat Valenciana (Prometeo2017/139), and MINECO-Spain (Grant No. PID2019-109539GB-C41). J.F.R. and D.J. acknowledge funding from FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Grant No. P18-FR-4834

Exactly solvable associated Lame potentials and supersymmetric transformations

A systematic procedure to derive exact solutions of the associated Lame equation for an arbitrary value of the energy is presented. Supersymmetric transformations in which the seed solutions have factorization energies inside the gaps are used to generate new exactly solvable potentials; some of them exhibit an interesting property of periodicity defects.Comment: Annals of Phys.(in press); Present e-mail of AG: [email protected]

Quantum mechanical spectral engineering by scaling intertwining

Using the concept of spectral engineering we explore the possibilities of building potentials with prescribed spectra offered by a modified intertwining technique involving operators which are the product of a standard first-order intertwiner and a unitary scaling. In the same context we study the iterations of such transformations finding that the scaling intertwining provides a different and richer mechanism in designing quantum spectra with respect to that given by the standard intertwiningComment: 8 twocolumn pages, 5 figure

Conceptual design of the EU-DEMO dual coolant lithium lead equatorial module

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Within the framework of EUROfusion Program, the Dual Coolant Lithium Lead (DCLL) is one of the four EU breeder blanket concepts that are being investigated as candidates for DEMO. DCLL uses PbLi as the main coolant, tritium breeder, tritium carrier, and neutron multiplier. The main structures, including the first wall, are cooled with helium. The EU program proposed for the next years will consider a DCLL version limited to 550 °C in order to allow the use of conventional materials and technologies. During the first year of EUROfusion activities, a draft design of the DCLL has been proposed. The main blanket performances were adapted to the new specifications and the CAD model of DEMO. The breeder zone has been toroidally divided into four parallel PbLi circuits, separated through stiffening grid radial walls. The PbLi flow routing has been designed to maximize the amount of thermal power extracted by flowing PbLi and to avoid the occurrence of reverse flows due to volumetric heating. Thermal hydraulics, magnetohydrodynamic and neutronics calculations have been performed for the first draft design. The new DCLL design employs Eurofer-alumina-Eurofer sandwich as flow channel insert (FCI).Postprint (published version

Effect of the thermal characteristics of dielectric fluids on the loading capacity of a power transformer

The use of biodegradable dielectric liquids in power transformers has several advantages, such as increased fire safety or their biodegradability in the event of a leak in the tank. However, they also have a higher viscosity that does not benefit their cooling function within these machines. Although there are many references that analyze the transformers hotspot temperature for dynamic loading, there are hardly any references that focus on the dynamic evaluation of the hotspot when the viscosity of the dielectric and cooling fluid changes, with respect to that of the oil of mineral origin. In this work, the algorithms proposed in the bibliography will be combined with the use of computational fluid dynamics software ANSYSFLUENT, which uses the finite volumes method to solve the equations that govern fluid flow. The software tool will be used to calculate the temperatures of a 100MVA transformer winding. Once these temperatures have been calculated, they can be entered into the hotspot temperature estimation algorithm when the machine's load regime is varied. This analysis will be repeated using dielectric liquids with different thermal characteristics. Transformer fleet managers may use the results of this study in order to adapt their procedures when the machines they manage do not have conventional mineral oil insidePart of the work was performed during secondments between University of Valle and the Universidad de Cantabria executed in the framework of the BIOTRAFO project “Raising knowledge and developing technology for the design and deployment of high performance power transformers immersed in biodegradable fluids”, H2020-MSCARISE-2018-823969, 2019–21. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823969. Also, we acknowledge the support of the Spanish Ministry of Science and Innovation by means of the National Research Project Asset management of biodegradable-fluid-based transformers (PID2019-107126RB-C22/AEI/10.13039/501100011033). The authors also want to thank the grant received from the Call for the Development of the 2020 Industrial Doctorate Program of the Universidad de Cantabria