Jose-Luis Perez-Diaz | Universidad de Alcalá (original) (raw)

Papers by Jose-Luis Perez-Diaz

Journal of heat transfer, Jun 4, 2010

Drift chambers in the compact muon solenoid (CMS) detector are piled modular structures joined to... more Drift chambers in the compact muon solenoid (CMS) detector are piled modular structures joined together by a structural adhesive. This structure is used for the detection and tracking of high energy particles—particularly muons. According to Fourier’s law, the conductance of a multilayered drift chamber prototype can be measured using a simple device based on the thermal transience between two heat sinks. The heat gradients in the global CMS detector in operation at the European Council for Nuclear Research are estimated in this way. The resultant values are used to determine whether to include a forced cooling device in the CMS.

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Mar 25, 2014

In this study, the mechanical design and analysis of a magnetic levitating linear bearing suitabl... more In this study, the mechanical design and analysis of a magnetic levitating linear bearing suitable for working in the nonhysteretic range of forces is presented. The semi-cylindrical design of the superconductor provides stable equilibrium positioning and restoring forces in all degrees of freedom except for two with a cylindrical magnet floating along the axis of revolution/displacement. Using finite element analysis, it has been proven that the magnet can float stably and passively in a complete non-hysteretic Meissner state. This non-hysteretic passive linear bearing could be suitable for long-stroke precision positioning. The high translational symmetry of the magnetic field seen by the superconductor assures a usable long stroke of around AE90 mm with full performance and AE150 mm with reduced performance. This linear bearing in combination with an actuating system for only one degree of freedom could be used for accurate precision positioning systems for cryogenic environments with zero hysteresis in the movement.

Applied Physics Letters, Oct 1, 2007

The force between a magnetic dipole and a finite superconductor in the Meissner state (H<H... more The force between a magnetic dipole and a finite superconductor in the Meissner state (H<Hc1) is calculated by using an expression based on London’s and Maxwell’s equations. It demonstrates the existence of attractiveness and stability. The finiteness of a piece of superconductor therefore suffices to explain a stability for the levitation of a magnet over it or even the suspension of one of them under the other one. This does not contradict the existence of flux penetration. However, this makes the flux penetration not necessary to explain both stability and attractiveness, as has been assumed until now.

Smart Materials and Structures, Jan 25, 2019

Phase Transitions, Feb 7, 2018

The surface photo charge effect (SPCE) was applied for the first time at structure and phase tran... more The surface photo charge effect (SPCE) was applied for the first time at structure and phase transitions study of hydrogen bonded in dimer liquid crystals (HBDLCs). Due to the high sensitivity of this method, besides firstorder phase transitions, characteristic for the p,n-octyloxibenzoic acids (8OBA), an order transition was definitely detected within the nematic range. We state that the SPCE, arising at the solid-HBDLCs interface due to the double electrical layer, is invariably concomitant with solid surfaceliquid interfaces, and indicates that the changes of the characteristics of this layer, under incident optical irradiation, induce surface charge rearrangement and alternating potential difference. A mechanism of induction of the SPCE at the interface of solid surface-anisotropic liquids is proposed. We also indicate that this mechanism can be adapted for solid surface-isotropic liquid interface, including colloids (milk) and fog (aerosols)-condensed medium.

Journal of Sound and Vibration, Mar 1, 2019

ESA Special Publication, Sep 1, 2015

Harmonic drives are profusely used in aerospace mainly because of their compactness and large red... more Harmonic drives are profusely used in aerospace mainly because of their compactness and large reduction ratio. However, their use in cryogenic environments is still a challenge. Lubrication and fatigue are non-trivial issues under these conditions. The objective of the Magnetic-Superconductor Cryogenic Non-contact Harmonic Drive (MAGDRIVE) project, funded by the EU Space FP7, is to design, build, and test a new concept of MAGDRIVE. Non-contact interactions among magnets, soft magnetic materials, and superconductors are efficiently used to provide a high reduction ratio gear that smoothly and naturally operates at cryogenic environments. The limiting elements of conventional harmonic drives (teeth, flexspline, and ball bearings) are substituted by contactless mechanical components (magnetic gear and superconducting magnetic bearings). The absence of contact between moving parts prevents wear, lubricants are no longer required, and the operational lifetime is greatly increased. This is the first mechanical reducer in mechanical engineering history without any contact between moving parts. In this paper, the test results of a −1:20 inverse reduction ratio MAGDRIVE prototype are reported. In these tests, successful operation at 40 K and 10 −3 Pa was demonstrated for more than 1.5 million input cycles. A maximum torque of 3 N• m and an efficiency of 80% were demonstrated. The maximum tested input speed was 3000 rpm, six times the previous existing record for harmonic drives at cryogenic temperatures.

IEEE Transactions on Applied Superconductivity, Dec 1, 2019

Superconducting magnetic levitation has been used in contactless mechanical components for differ... more Superconducting magnetic levitation has been used in contactless mechanical components for different applications like bearings or positioning devices. This technology is currently being investigated for its potential use as a vibration isolation and thermal disconnect passive mechanism to support the focal plane array of the ESA ATHENA scientific telescope. Although it is well known that superconducting levitation properties depends on temperature, theoretical models have difficulties with complex bearing geometries or capturing inhomogeneity in material properties. In addition, experimental studies focused on the characterization of the mechanical properties of superconducting magnetic bearings are scant and mostly carried out with zero-field-cooled thrust bearing configurations. In order to increase the maturity of the technology for its potential use in space applications, further experimental research of the superconducting levitation properties at different temperatures is required. In this paper, we present the results of an experimental study of the levitation mechanical properties of a journal superconducting suspension in a high vacuum and temperatures from 90 to 12 K. Axial stiffness quadratically increases at lower temperature and linearly in the radial direction. However, the hysteresis loss factor decreases when decreasing the temperature for both axial and radial directions of displacement. These results demonstrate that the temperature influence on superconducting levitation systems is significant, and thus, mechanical engineers must consider it for design of superconducting levitation systems subjected to temperature variations.

Ceramics International, Jul 1, 2020

Abstract Superconducting single-domain YBCO and GdBCO/Ag bulks were tested for space and nuclear ... more Abstract Superconducting single-domain YBCO and GdBCO/Ag bulks were tested for space and nuclear applications by an exposition to increasing doses of gamma and neutron radiation in the LVR-15 research reactor. Maximum doses were 3.85E+04 Gy from neutron and 7.00E+05 Gy from gamma radiation, which is much larger dose then can be received in any spacecraft during the standard space mission. Levitation force and trapped field of the irradiated samples as well as non-irradiated samples were measured after each irradiation step. The appearance and phase composition of the surface and interior of all samples were examined by XRD and SEM after the final irradiation. The surface of the ceramics was damaged in respect of visual (SEM) appearance and the phase composition (XRD). Nevertheless, the interior is similar to the standard non-irradiated samples. More importantly, the trapped field and the levitation force remained also comparable for irradiated and non-irradiated samples even after the highest dosage experiment. From the results it is apparent, that the superconducting levitation discs of similar composition, shape and size can be securely used for space applications as well as for nuclear applications when the dose of irradiation is comparable to the undertaken experiments. The attention has to be paid to the very small parts, where the surface damage may cause some problems in performance.

Machines, Sep 7, 2016

Actual aerospace and defense technologies present multiple limitations that need to be overcome i... more Actual aerospace and defense technologies present multiple limitations that need to be overcome in order to evolve to less contaminating and more efficient aircraft solutions. Contactless technologies come with essential advantages such as the absence of wear and friction. This work describes the design, prototype, and performance test according to RTCA-DO-160 of an aeronautical magnetic torque limiter. The results show correct continuous transmission operation (2250 rpm and 24 Nm) from −50 • C to +90 • C. Moreover, overload protection has been demonstrated for more than 200 jamming events without damage or required maintenance to the device.

Journal of Applied Physics, Feb 12, 2013

Forces and torques exerted by a superconducting torus on a permanent magnet have been mapped. It ... more Forces and torques exerted by a superconducting torus on a permanent magnet have been mapped. It is demonstrated that stable orbits exist. Moreover, provided that the magnet remains in any of these orbits, the first critical field in the superconductor is never overpassed and the superconductor remains in the Meissner state. The consequent absence of hysteresis makes these kinds of device perfect candidates for non-frictional bearings or gyroscopes.

Physical review, Sep 15, 1994

The electronic properties of fcc Cu(100) and Co(100) surfaces and of the Co/Cu (100) interface ar... more The electronic properties of fcc Cu(100) and Co(100) surfaces and of the Co/Cu (100) interface are studied by the surface Green function matching method and an empirical tight-binding model. The band structures and layer densities of states allow us to establish the short-range character of surface and interface-induced effects. The Co surface exhibits a slightly reduced magnetic moment. At the interface, the spin polarizations and magnetic moments for both localized d-electrons and nearly free Bp electrons are induced at the Cu layer.

International Journal of Environmental Research and Public Health, Dec 29, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Physical review, May 15, 1996

ABSTRACT

Journal of physics, May 12, 2014

Superconducting magnetic bearings (SMBs) can provide stable levitation without direct contact bet... more Superconducting magnetic bearings (SMBs) can provide stable levitation without direct contact between them and a magnetic source (typically a permanent magnet). In this context, superconducting magnetic levitation provides a new tool for mechanical engineers to design non-contact mechanisms solving the tribological problems associated with contact at very low temperatures. In the last years, different mechanisms have been proposed taking advantage of superconducting magnetic levitation. Flywheels, conveyors or mechanisms for high-precision positioning. In this work the mechanical stiffness of a journal SMBs have been experimentally studied. Both radial and axial stiffness have been considered. The influence of the size and shape of the permanent magnets (PM), the size and shape of the HTS, the polarization and poles configuration of PMs of the journal SMB have been studied experimentally. Additionally, in this work hysteresis behavior and force relaxation are considered because they are essential for mechanical engineer when designing bearings that hold levitating axles.

Physical Review Letters, Apr 11, 1994

The long-wavelength oscillations observed in magnetic multilayers are explained by an indirect Ru... more The long-wavelength oscillations observed in magnetic multilayers are explained by an indirect Ruderman-Kittel-Kasuya-Yosidalike (RKKY) exchange interaction. A perturbative theory of the RKKY-like exchange coupling between two ferromagnetic layers separated by a nonmagnetic slab is derived. The approach includes a realistic description of the multilayer one-electron states, whose wave functions satisfy matching conditions at the ferromagnetic-nonmagnetic interfaces. The quantum-size efFects exhibited by the electron transmission coefBcient give rise to a distinct multilayer wavelength A, which provides the measured long periods.

Microorganisms, Apr 14, 2023

Journal of Applied Physics, May 15, 1994

We have investigated the Fe/Au, Ag, Pt, and Al(001) single interfaces by means of an empirical ti... more We have investigated the Fe/Au, Ag, Pt, and Al(001) single interfaces by means of an empirical tight-binding Hamiltonian within the Green’s function matching formalism. The method is exact and describes equally interface states and bulk resonances. The evolution of the layer density of states indicates a rearrangement of the electronic density at the interface in form of spin polarization of the nonmagnetic layers. The induced magnetic moments in the nonmagnetic layers are only appreciable in Pt and Al, while variations of the interface Fe magnetization are predicted for all the systems.