Harold S Ruiz

Harold S Ruiz
University of Leicester | LE · Department of Engineering

PhD Applied Physics & Materials Science
Associate Professor on Energy Materials and Power Systems; Director of Electrical Engineering at University of Leicester

About

60
Publications
4,996
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529
Citations
Additional affiliations
January 2014 - present
University of Cambridge
Position
  • Scientific Research Associate

Publications

Publications (60)
Article
Full-text available
When compared with rare-earth coated conductors, magnesium diboride superconducting cables are known to show significant advantages by cost and easy production. However, the inherent difficulty for achieving a significant reduction of their magnetization losses in multifilamentary wires, without degrading the high critical current density that is s...
Preprint
A better understanding of the interaction between three phases is required when developing superconducting cables for high voltage AC systems. With a particular focus on the energy losses of real power transmission cables, in this paper we utilize the so-called H-formulation of Maxwell equations to devise a 2D model for superconducting triaxial cab...
Preprint
The Conductor on Rounded Core (CORC) cables manufactured by Advanced Conductor Technologies with current densities beyond 300 Amm^-2 at 4.2 K, and bending diameter of up to 3.5 cm, are considered as one of the strongest candidates for the next generation of high field power applications and magnets. In this paper, we present a full 3D FEM model for...
Preprint
Conductor on a rounded core (CORC\textsuperscript{\textregistered}) cables with current densities beyond 300 A/mm$^{-2}$ at 4.2 K, and a capacity to retain around 90 $\%$ of critical current after bending to a diameter of 3.5 cm, make them a strong candidate for high field power applications and magnets. In this paper, we present a full 3D-FEM mode...
Article
Full-text available
Improving our understanding of the physical coupling between type-II superconductors (SC) and soft ferromagnetic materials (SFM) is the root for progressing to the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and power transmission systems. However, in the latter, some intriguing and yet unexplain...
Preprint
Improving our understanding of the physical coupling between type-II superconductors (SC) and soft ferromagnetic materials (SFM), is root for progressing onto the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and power transmission systems. However, in the latter some intriguing and yet unexplained...
Preprint
Full-text available
Understanding the physical coupling between the macroscopic electromagnetic properties of type II superconductors (SC) and soft ferromagnetic materials (SFM), is root for progressing onto the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and loss free current transmission systems. However, in the l...
Article
Full-text available
A reliable tool for site-suitability assessment of solar power plants capable to account for the protection of cultural, natural, and ecological conservation areas is proposed. The tool integrates an Analytic Hierarchy Process (AHP) based Multi Criteria Decision Analysis (MCDA) algorithm into a Geographical Information System (GIS) package, which c...
Article
Full-text available
This paper presents a technical and economic feasibility assessment of utility-scale solar photovoltaic (PV) plants in the West Kalimantan Province of Borneo, which is essential for boosting the development of solar PV plants in Indonesia. The assessment was performed based on a previously developed geographical information systems (GIS) package th...
Preprint
Full-text available
A reliable tool for site-suitability assessment of solar power plants capable to account for the sustainable development and protection of cultural and biodiversity conservation areas is proposed. We present a novel Analytic Hierarchy Process (AHP) based approach for the Multi-Decision Criteria Analysis (MDCA) of SSI satellite retrieved data and lo...
Article
Full-text available
A comprehensive study of the quench properties of single laminated wires having a double-layered superconducting structure is presented. In particular, we have focused on the influence of the angle and intensity of an external magnetic field perpendicular to direction of the applied current on the minimum quench energy (MQE) and normal zone propaga...
Article
A noteworthy physical dependence of the hysteresis losses with the axial winding misalignment of superconducting racetrack coils made with commercial second generation high temperature superconducting (2G-HTS) tapes is reported. A comprehensive study on the influence of the turn-to-turn misalignment factor on the local electromagnetic properties of...
Article
Full-text available
In an attempt to unveil the impact of the material law selection on the numerical modelling and analysis of the electromagnetic properties of superconducting coils, in this paper we compare the four most common approaches to the E-J power laws that serve as a modelling tool for the conductivity properties of the second generation of high-temperatur...
Preprint
Full-text available
A noteworthy physical dependence of the hysteresis losses with the axial winding misalignment of superconducting racetrack coils made with commercial \textcolor{black}{Second Generation High Temperature Superconducting (2G-HTS)} tapes is reported. A comprehensive study on the influence of the turn-to-turn misalignment factor on the local electromag...
Article
The AC losses induced by an alternating transport current in type-II superconductors is a well known phenomena which still attracts much attention due to its intrinsic relevance for the proper development of practical applications. In the case of single core superconducting cables of cylindrical crosssection, it is possible to find exact analytical...
Article
Full-text available
The extremely low decay factor on the trapped magnetic field by stacks of second-generation high-temperature superconducting tapes reported in Appl. Phys. Lett. 104, 232602 (2014), is in apparent contradiction with the classical results for the demagnetization of superconducting bulks and thin films, where the samples undergo a severe and progressi...
Article
Full-text available
The extremely low decay factor on the trapped magnetic field by stacks of second-generation high-temperature superconducting tapes reported in Appl. Phys. Lett. 104, 232602 (2014), is in apparent contradiction with the classical results for the demagnetization of superconducting bulks and thin films, where the samples undergo a severe and progressi...
Article
Remarkable features on the magnetic moment of type-II superconducting (SC) wires of cylindrical shape, subjected to direct current conditions (DC) and transverse oscillating (AC) magnetic fields, are reported. We show how for relatively low amplitudes of the applied magnetic field, B a, the superconducting wire rapidly develops a saturation state,...
Article
The macroscopic electromagnetic behavior of a type-II superconducting (SC) wire for alternating current (ac) power transmission under constant magnetic field conditions is captured by the numerical solution of the Maxwell equations under the framework of the critical state principle and the so-called integral formulation, also known as J-formulatio...
Article
Type-II superconductors are expected to be extensively used in the designing of DC power grids due to their reduced use of space, high transport current capability, and nearly zero resistive losses. Nevertheless, these systems will have to share the right of way of the currently installed AC network, reducing the costs of development associated to...
Article
The authors regret that one of the contributors in this paper was not brought in the list of authors, therefore, we will be very grateful to add the following contributor as the third author: Dr. Mehdi Baghdadi Faculty of Engineering, University of Greenwich, London SE10 9LS. [email protected] The new author list should be following: Z. Zhonga, M....
Article
This paper presents a novel method to determine the optimal strategy for the allocation of multiple resistive superconducting fault current limiters (SFCLs) aiming to improve the overall protection of standard power grids. The presented approach allows for the straightforward determination of the optimal resistance of the SFCL, accounting for short...
Article
Nowadays, superconducting high field magnets are used in numerous applications due to their superior properties. High temperature superconductors (HTS) are usually used for production of circular pancake or racetrack coils. However different geometries of HTS coils might be required for some specific applications. In this study, the HTS coil wound...
Article
A fully high temperature superconducting (HTS) motor has been built in the EPEC laboratory at the University of Cambridge, UK. Two different pulsed field magnetization (PFM) strategies have been implemented for studying the magnetization of a cylindrical rotor designed by an asymmetric array of superconducting bulks. Asymmetric or uneven distributi...
Article
Full-text available
The physical understanding and numerical modelling of superconducting devices which exploit the high performance of second generation high temperature superconducting tapes (2G-HTS), is commonly hindered by the lack of accurate functions which allow the consideration of the in-field dependence of the critical current. This is true regardless of the...
Article
High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new c...
Article
Full-text available
The physical understanding and numerical modelling of superconducting devices which exploit the high performance of second generation high temperature superconducting tapes (2G-HTS), is commonly hindered by the lack of accurate functions which allow the consideration of the in-field dependence of the critical current. This is true regardless of the...
Article
Full-text available
Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by c...
Article
High magnetic field can be trapped in a bulk type-II superconductor through different magnetization methods. In our fully high-temperature superconducting (HTS) synchronous motor, the pulsed field magnetization (PFM) method is adopted due to its reduced cost, feasibility, and adaptability on the assembling of our HTS motor system. The HTS rotor was...
Article
Based on the conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on the electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned mod...
Article
Full-text available
In the past few years there has been a significant rise in the short-circuit current levels in transmission and distribution networks, it due to the increasing demands on power and the addition of sources of distributed generations. It leads to the need of integration of novel protection systems such as the superconducting fault current limiters (S...
Article
Full-text available
In recent years, major industrialized countries have begun to be concerned about the need for developing strategies on the integration and protection of the growing power capacity of renewable source energies, attracting back their interest on the development and understanding of superconducting fault current limiters (SFCLs). The reasons for this...
Article
Full-text available
This paper investigates the practical effectiveness of employing superconducting stacked tapes to superconducting electric machinery. The use of superconducting bulks in various practical applications has been addressed extensively in the literature. However, in practice, dramatic decrease in magnetization would occur on superconducting bulks due t...
Article
The Normal zone propagation velocity (NZPV) of a double-layer second generation high temperature superconducting wire manufactured by American Superconductor has been measured by electrical and thermal methods, and the results have been compared and discussed. The NZPV values determined by the voltage traces are ranging from 3.8 mm/s at 0.4 to 19.2...
Article
Full-text available
The crossed-magnetic-field effect on the demagnetization factor of stacked second generation (2G) high temperature superconducting tapes is presented. The superconducting sample was initially magnetized along the c-axis by the field cooling magnetization method and after achieving the magnetic relaxation of the sample, an extensive set of experimen...
Chapter
The high interest concerning the investigation of themacroscopicmagnetic properties of type-II superconductors in the mixed state is markedly associated with its relevance to technological and industrial applications achieving elevated transport currents with no discernible energy dissipation. It relates to a wide list of physical phenomena concern...
Article
Around straight superconducting wire has been used as numerical prototype for pursuing a comprehensive study on the local distribution of current and the density of power losses, attained by the simultaneous action of an ac transport current and an oscillating transverse magnetic field. The numerical simulations have been performed within the quasi...
Article
The time-dependent local electromagnetic properties of a type-II superconducting wire subject to the concomitant action of an ac transport current and an oscillating transverse magnetic field in synchronous and asynchronous regimes are thoroughly studied under the critical state approach. Relative double frequency effects between the electromagneti...
Article
Full-text available
Numerical simulations of a type-II superconducting wire subject to an ac transport current and oscillating transverse magnetic field are performed using the theory of the critical state. Time-dependent distributions of the current and the density of magnetic flux, the local power dissipation, and cycles of the magnetic moment are displayed. Noticea...
Article
Full-text available
Contents Preface I Electromagnetism of type II superconductors 1 General Statements Of The Critical State 1.1 The CS In The Maxwell Equations Formalism 1.2 The CS Regime And The MQS Limit 2 Variational Theory for CS Problems 2.1 General Principles Of The Variational Method 2.2 The Material Law: SCs with magnetic anisotropy 2.2.1 Onto the 1D Critica...
Article
Despite the intensive efforts for determining the mechanism that causes high-temperature superconductivity in copper oxide materials, no consensus on the pairing mechanism has been reached. Recent advances in high resolution angle-resolved photoemission spectroscopies have suggested that a sizeable electron-phonon coupling exists as the principal c...
Article
Full-text available
Relying on our theoretical approach for the superconducting critical state problem in 3D magnetic field configurations, we present an exhaustive analysis of the electrodynamic response for the so-called longitudinal transport problem in the slab geometry. A wide set of experimental conditions have been considered, including modulation of the applie...
Article
Full-text available
Numerical simulations of filamentary type II superconducting wires under simultaneous AC transport current and oscillating transverse magnetic fields are performed within the critical state approximation. The time dependences of the current density profiles, magnetic flux lines, local power dissipation and magnetic moment are featured. Noticeable n...
Article
Full-text available
Despite the intensive efforts for determining the mechanism that causes high-temperature superconductiv-ity in copper oxide materials (cuprates), no consensus on the pairing mechanism has been reached. Recent advances in angle-resolved photoemission spectroscopies (ARPES) have suggested that a sizeable electron–phonon coupling ex-ists as the princi...
Article
Full-text available
Several aspects of the general theory for the critical states of a vortex lattice and the magnetic flux dynamics in type-II superconductors are examined by a direct variational optimisation method and widespread physical principles. Our method allows to unify a number of conventional models describing the complex vortex configurations in the critic...
Article
Full-text available
The longitudinal transport problem (the current is applied parallel to some bias magnetic field) in type-II superconductors is analyzed theoretically. Based on analytical results for simplified configurations, and relying on numerical studies for general scenarios, it is shown that a remarkable inversion of the current flow in a surface layer may b...
Article
Full-text available
Despite the intensive efforts for determining the mechanism that causes high-temperature superconductivity in copper oxide materials, no consensus on the pairing mechanism has been reached. Recent advances in high resolution angle-resolved photoemission spectroscopies have suggested that a sizeable electron-phonon coupling exists as the principal c...
Article
Full-text available
The magnetic flux dynamics of type-II superconductors within the critical state regime is posed in a generalized framework, by using a variational theory supported by well established physical principles. The equivalence between the variational statement and more conventional treatments, based on the solution of the differential Maxwell equations t...
Article
Original title, Spanish edition: El Kink en la Espectroscopía de Fotoemisión de Ángulo Resuelto (ARPES) para el BI2212 óptimamente dopado
Article
Full-text available
Original title, Spanish edition: La Resonancia en la Conductividad Óptica de Superconductores Óptimamente Dopados
Article
Original title, Spanish edition: Reajuste Vértice en Espectro Óptico de Superconductores Cuasi-Isotròpicos
Article
Full-text available
The experimental finding of an ubiquitous kink in the nodal direction of angle-resolved photoemission spectroscopies of superconducting cuprates has been reproduced theoretically. Our model is built upon the Migdal-Eliashberg theory for the electron self-energy within the phonon-coupling scenario. Following this perturbative approach, a numerical e...
Article
Full-text available
The relevance of the strong correlations in the high critical temperature superconductors (HTSC) is well experimentally documented. However, if the properties of the normal and superconducting state in HTSC oxides are interpreted in terms of the standard Eliashberg theory, which holds in low temperature superconductor systems, the Migdal–Eliashberg...
Article
Full-text available
Original Title, Spanish edition ACERCAMIENTO AL CÁLCULO DE LA MASA EFECTIVA DE UNA CADENA CLÁSICA LINEAL

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Projects

Projects (4)
Project
This project is supported by the Institutional Links grants program, under the Newton Fund Indonesia partnership. The grant is funded by the UK Department for Business, Energy and Industrial Strategy and the Indonesian Ristekdikti (Kementerian Riset Teknologi, dan Pendidikan Tinggi - Ministry of Research, Technology, Higher Education), and delivered by the British Council.
Project
This project is aimed to develop an integrated Geographic Information System for an accurate setting of surface solar irradiance maps (SSI) provided by the World Bank Group and other GIS and satellite raster databases, merging local sources of information provided by local stakeholders, which will enable the further consideration of vulnerability zones. The output of the projects should provide decision tools for government and industry sectors, aiming the planning of large-scale solar power plants in the West Kalimantan area (Indonesia).