Localised projective measurement of a relativistic quantum field in non-inertial frames

We propose a scheme to study the effect of motion on measurements of a quantum field carried out by a finite-size detector. We introduce a model of projective detection of a localised field mode in an arbitrary reference frame. We apply it to extract vacuum entanglement by a pair of counter-accelerating detectors and to estimate the Unruh temperature of a single accelerated detector. The introduced method allows us to directly relate the observed effects with the instantaneous proper acceleration of the detector.Comment: 5 pages, 2 figures. v2 Significant increase in the detail level regarding the motivation of the detector mode

An upper bound for the magnetic force gradient in graphite

Cervenka et al. have recently reported ferromagnetism along graphite steps. We present Magnetic Force microscopy (MFM) data showing that the signal along the steps is independent of an external magnetic field. Moreover, by combining Kelvin Probe Force Microscopy (KPFM) and MFM, we are able to separate the electrostatic and magnetic interactions along the steps obtaining an upper bound for the magnetic force gradient of about16 microN/m, a figure six times lower than the lowest theoretical bound reported by Cervenka et al. Our experiments suggest absence of MFM signal in graphite at room temperature.Comment: 14 pages, including supplemetary informatio

Phenomenological based model of hydrogen production using an alkaline self-pressurized electrolyzer

© 2019 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.The aim of this work is to develop the phenomenological based modeling of a self-pressurized alkaline electrolyser with the objective of predicting the cross-contamination of the gases produced. A proposed model, built in Matlab®, represents the dynamical evolution in real electrolysers, and anticipates operational variables: level, pressure and all concentrations. Dynamic responses in the concentrations of the electrolytic cell, and variations in both level and pressure at the chamber due to the change in current and diffusivity, are reported. The equations by which the variables can be computed are also presented. The proposed model is ready for the corresponding adjustment of parameters based on experimental measurements taken from an available prototype and through a suitable identification process.Peer ReviewedPostprint (author's final draft

Local convexity for second order differential equations on a Lie algebroid

A theory of local convexity for a second order differential equation (SODE) on a Lie algebroid is developed. The particular case when the SODE is homogeneous quadratic is extensively discussed.Comment: 25 pages. To appear in Journal of Geometric Mechanics. arXiv admin note: substantial text overlap with arXiv:1608.0158

Agreement of Tear Break-Up Time and Meniscus Height between Medmont E300 and Visionix VX120+

The goal of this study was to analyze the agreement between the Medmont E300 and the Visionix VX120+ systems in terms of non-invasive tear break-up time (NIBUT) and tear meniscus height (TMH) measurements. A total of 60 eyes (30 healthy subjects) were enrolled. NIBUT and TMH were evaluated with Medmont E300; first NIBUT, NIBUT50%, and TMH were evaluated with Visionix VX120+. Both evaluations were performed in a random order by the same clinician for right, left, and both eyes. The Medmont E300 provided significantly higher NIBUT than Visionix VX120+ for first NIBUT in right, left, and both eyes (p ≤ 0.003) and NIBUT50% in left and both eyes (p ≤ 0.042). The TMH measured with VX120+ was significantly higher than with Medmont E300 considering both eyes (p = 0.037). No significant correlations were found between both devices for either NIBUT (p ≥ 0.11) or TMH (p ≥ 0.09). Passing–Bablok regression analyses revealed poor agreement between devices for NIBUT and TMH outcomes. VX120+ is expected to provide substantial lower first NIBUT values than the NIBUT measured by Medmont E300. Clinicians should consider not using both instruments as interchangeable for dry eye diagnosis.The author D.P.P. has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471. This research received no external funding. E.M.P. has been supported by European Union-NextGenerationEU

In situ chemical modification of C–S–H induced by CO2 laser irradiation

The final publication is available at Springer via http://dx.doi.org/10.1617/s11527-018-1150-yFire-induced compositional changes lead to strength loss and even failure in cement and concrete. Calcium silicate hydrate (C–S–H) gel, the main product of cement hydration, dehydrates at 25–200 °C, while temperatures of 850–900 °C alter its structure. A Raman spectroscopic study of the amorphous and crystalline phases forming after CO2 laser radiation of cement mortar showed that C–S–H dehydration yielded tricalcium silicate at higher, and dicalcium silicate at lower, temperatures. Post-radiation variations were identified in the position of the band generated by Si–O bond stretching vibrations.Peer ReviewedPostprint (author's final draft

Using smart cards for authenticating in public services: A comparative study

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-19713-5_37Smart cards are well-known tamper-resistant devices, and as such they represent an excellent platform for implementing strong authentication. Many services requesting high levels of security rely on smart cards, which provide a convenient security token due to their portability. This contribution analyses two Spanish smart card deployments intended to be used for accessing eGoverment services, comparing their respective contents and capabilities.This work has been partially supported by Comunidad de Madrid (Spain) under the project S2013/ICE-3095-CM (CIBERDINE)

Networks based on QKD and weakly trusted repeaters

We study how to use quantum key distribution (QKD) in common optical network infrastructures and propose a method to overcome its distance limitations. QKD is the first technology offering information theoretic secret-key distribution that relies only on the fundamental principles of quantum physics. Point-to-point QKD devices have reached a mature industrial state; however, these devices are severely limited in distance, since signals at the quantum level (e.g. single photons) are highly affected by the losses in the communication channel and intermediate devices. To overcome this limitation, intermediate nodes (i.e. repeaters) are used. Both, quantum-regime and trusted, classical, repeaters have been proposed in the QKD literature, but only the latter can be implemented in practice. As a novelty, we propose here a new QKD network model based on the use of not fully trusted intermediate nodes, referred as weakly trusted repeaters. This approach forces the attacker to simultaneously break several paths to get access to the exchanged key, thus improving significantly the security of the network. We formalize the model using network codes and provide real scenarios that allow users to exchange secure keys over metropolitan optical networks using only passive components

Swirl ratio and post injection strategies to improve late cycle diffusion combustion in a light-duty diesel engine

[EN] Nitrogen oxides (NOx) and soot emissions are the most important pollutants from direct-injection diesel engines. In particular, soot formation and oxidation determine the net engine-out soot emissions. These phenomena are complex and competing processes during diesel combustion. Despite many researches implicate the mechanisms of soot formation with soot emissions, the enhancement of the late cycle soot oxidation is the dominant mechanism for a reduction of engine-out soot emissions. The mixing process and the in-cylinder bulk temperature are two important parameters in the development of soot oxidation process. The current research compares different engine strategies to enhance the late cycle mixing controlled combustion process and therefore enhance soot oxidation while maintaining similar gross indicated efficiency in a light-duty engine. For this purpose, a simplified methodology has been used, which analyzes the effect of mixing process and in-cylinder bulk gas temperature on soot oxidation during the late cycle combustion. For carrying out this research, theoretical and experimental tools were used. In particular, the experimental measurements were made in a single-cylinder direct-injection light-duty diesel engine varying the swirl ratio and the injection pattern as injection pressure, Start of Energizing (SoE), Energizing Time (ET) and number of injections events. To analyze soot emissions, the combustion luminosity was measured by an optoelectronic probe and the optical thickness parameter (KL) was evaluated by the two-color pyrometry method. The apparent combustion time (ACT-1) was used as mixing time tracer. Results show that an increase in swirl ratio implies an improvement on the mixing process and higher values of average bulk temperature during the late-cycle diffusion combustion. Both phenomena produce an enhancement in the soot oxidation process. In the lowest swirl ratio case, a suitable injection strategy based on multiple injections, provides similar results of soot oxidation process (and therefore, the emissions) as high swirl ratio case. (C) 2017 Elsevier Ltd. All rights reserved.Benajes, J.; Martín, J.; García Martínez, A.; Villalta-Lara, D.; Warey, A. (2017). Swirl ratio and post injection strategies to improve late cycle diffusion combustion in a light-duty diesel engine. Applied Thermal Engineering. 123:365-376. doi:10.1016/j.applthermaleng.2017.05.101S36537612