Institute Tecnologias Fisicas Y Of La Informacion

Serrano, Spain

Institute Tecnologias Fisicas Y Of La Informacion

Serrano, Spain
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D. Cardell S.,University of Campinas | Fuster-Sabater A.,Institute Tecnologias Fisicas Y Of La Informacion
Finite Fields and their Applications | Year: 2017

In this work, different decimation-based sequence generators for cryptographic purposes have been analyzed in detail. In fact, the modified self-shrinking generator was first introduced as an improved version of the self-shrinking generator. However, it is here proven that the sequences produced by both generators belong to the same family of sequences, that is the class of the generalized self-shrinking sequences. Thus, both sequences have the same properties as well as the same weaknesses. Moreover, such sequences can be generated by linear structures based on one-dimensional cellular automata. The linearity inherent to the cellular automata-based models can be used to launch a cryptanalytic attack against such non-linear generators. © 2017 Elsevier Inc.

Peinado A.,University of Malaga | Munilla J.,University of Malaga | Fuster-Sabater A.,Institute Tecnologias Fisicas Y Of La Informacion
Sensors (Switzerland) | Year: 2014

This paper analyzes the cryptographic security of J3Gen, a promising pseudo random number generator for low-cost passive Radio Frequency Identification (RFID) tags. Although J3Gen has been shown to fulfill the randomness criteria set by the EPCglobal Gen2 standard and is intended for security applications, we describe here two cryptanalytic attacks that question its security claims: (i) a probabilistic attack based on solving linear equation systems; and (ii) a deterministic attack based on the decimation of the output sequence. Numerical results, supported by simulations, show that for the specific recommended values of the configurable parameters, a low number of intercepted output bits are enough to break J3Gen. We then make some recommendations that address these issues. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

PubMed | Hospital Clinico San Carlos, Institute Tecnologias Fisicas Y Of La Informacion and Massachusetts Institute of Technology
Type: Journal Article | Journal: Ultrasound in medicine & biology | Year: 2016

Accurate measurement of very low cerebrospinal fluid (CSF) white blood cell (WBC) concentration is key to the diagnosis of bacterial meningitis, lethal if not promptly treated. Here we show that high frequency ultrasound (HFUS) can detect CSF WBC invitro in concentrations relevant to meningitis diagnosis with a much finer precision than gold standard manual counting in a Fuchs-Rosenthal chamber. WBC concentrations in a mock CSF model, in the range 0-50 WBC/L, have been tested and compared to gold standard ground truth. In this range, excellent agreement (Cohens kappa []=0.78-90) (Cohen 1960) was observed between HFUS and the gold standard method. The presented experimental set-up allowed us to detect WBC concentrations as low as 2cells/L. HFUS shows promise as a low-cost, reliable and automated technology to measure very low CSF WBCconcentrations for the diagnosis of early meningitis.

Cardell S.D.,University of Alicante | Fuster-Sabater A.,Institute Tecnologias Fisicas Y Of La Informacion
Procedia Computer Science | Year: 2015

In this work, we propose a cryptanalysis of the nonlinear sequence generator called the shrinking generator. The output sequence of this cryptographic generator, the shrunken sequence, can be modelled as one of the output sequences of linear cellular automata (CA). The shrunken sequence and the other sequences generated by the CA can be reduced to a combination of PN-sequences generated by the same characteristic polynomial. Therefore, all these PN-sequences are the same but shifted. We propose an efficient cryptanalysis that takes advantage of the linearity of these PN-sequences and the CA. © The Authors. Published by Elsevier B.V.

Rosado Maria E.,Technical University of Madrid | Munoz Masque J.,Institute Tecnologias Fisicas Y Of La Informacion
Differential Geometry and its Application | Year: 2014

Second-order Lagrangian densities admitting a first-order Hamiltonian formalism are studied; namely, i) necessary and sufficient conditions for the Poincaré-Cartan form of a second-order Lagrangian on an arbitrary fibred manifold p:E→N to be projectable onto J1E are explicitly determined; ii) for each of such Lagrangians, a first-order Hamiltonian formalism is developed and a new notion of regularity is introduced; iii) the variational problems of this class defined by regular Lagrangians are proved to be involutive. © 2014 Elsevier B.V..

Elvira L.,Institute Tecnologias Fisicas Y Of La Informacion | Vera P.,University of Jaén | Canadas F.J.,University of Jaén | Shukla S.K.,Institute Tecnologias Fisicas Y Of La Informacion | Montero F.,Institute Tecnologias Fisicas Y Of La Informacion
Ultrasonics | Year: 2016

This work proposes the use of an ultrasound based technique to measure the concentration of yeasts in liquid suspension. This measurement was achieved by the detection and quantification of ultrasonic echoes backscattered by the cells. More specifically, the technique was applied to the detection and quantification of Saccharomyces cerevisiae. A theoretical approach was proposed to get the average density and sound speed of the yeasts, which were found to be 1116 kg/m3 and 1679 m/s, respectively. These parameters were needed to model the waves backscattered by each single cell. A pulse-echo arrangement working around 50 MHz, being able to detect echoes from single yeasts was used to characterize experimentally yeast solutions from 102 to 107 cells/ml. The Non-negative Matrix Factorization denoising technique was applied for data analysis. This technique required a previous learning of the spectral patterns of the echoes reflected from yeasts in solution and the base noise from the liquid medium. Comparison between pulse correlation (without denoising) and theoretical and experimental pattern learning was made to select the best signal processing. A linear relation between ultrasound output and concentration was obtained with correlation coefficient R2 = 0.996 for the experimental learning. Concentrations from 104 to 107 cells/ml were detected above the base noise. These results show the viability of using the ultrasound backscattering technique to detect yeasts and measure their concentration in liquid cultures, improving the sensitivity obtained using spectrophotometric methods by one order of magnitude. © 2015 Elsevier B.V. All rights reserved.

Bravo T.,Institute Tecnologias Fisicas Y Of La Informacion | Maury C.,École Centrale Marseille | Pinhede C.,CNRS Laboratory of Mechanics and Acoustics
22nd AIAA/CEAS Aeroacoustics Conference, 2016 | Year: 2016

The prediction and reduction of aerodynamic noise constitutes a continuous research subject since current trends within the automotive and aeronautic transport industries are directed towards integrated end-user and eco-friendly solutions, providing fuel efficiency by means of lighter and stiffer structures. Turbulent Boundary Layer (TBL) constitutes a broadband noise source for an aircraft under cruise conditions that contributes to cabin noise between 500 Hz and 2 kHz. The goal of this paper is to analyse the behavior of acoustic partitions composed of Micro-Perforated Panels (MPP) in situations where acoustic and turbulent excitations coexist. A theoretical model based on a fully-coupled modal expansion has been developed to analyse the response of finite-sized microperforated partitions excited by spatially correlated random fields such as a diffuse field, a TBL and a “rain on the roof” excitation. The analytical predictions have shown that the TL values increase progressively when considering less correlated random excitations. Verification of the analytical model has been carried out in a low-speed wind tunnel subjected to a TBL of 30.7 m/s free stream velocity. We have considered several single, double and triple partitions with the front panel, flush-mounted in the test section, being microperforated or not. For the double-layer configurations, microperforating the front panel of the double partition provides slightly lower overall TL performance with respect to the Panel-Cavity-Panel system. Comparisons between the measurements and the predicted analytical results provide an overall agreement either for a pure acoustic or for a TBL excitation. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

Aparicio C.,Institute Tecnologias Fisicas Y Of La Informacion | Elvira L.,Institute Tecnologias Fisicas Y Of La Informacion | Duran C.,Institute Tecnologias Fisicas Y Of La Informacion | Montero F.,Institute Tecnologias Fisicas Y Of La Informacion | Resa P.,Institute Tecnologias Fisicas Y Of La Informacion
Measurement Science and Technology | Year: 2014

A new ultrasonic resonator called MICRUS for measuring and characterizing liquid samples in continuous flow is presented. High accuracy and thermal stability are obtained by handling small liquid volumes passing through a heat exchanger before reaching the ultrasonic measurement chamber. The core measuring element consists of a resonant quartz flow-cell with LiNbO3piezoelectric discs attached face-to-face. The resonator is operated using pulsed excitation to provide rapid measurements. The software is implemented in LabView, giving a friendly and fully-automated interface well-suited for process monitoring. Different measurements for checking instrument performance (temperature stability, solute detection, measurement repeatability) are performed and a ±0.024 m s-1uncertainty is obtained. Application examples requiring liquid measurement under continuous flow conditions are also presented. When monitoring processes taking place in containers and conduits with uncontrolled thermal conditions, results show that measurement stability can be kept under 0.1 m s-1even when the sample temperature changes by more than 2°C due to environmental variations. © 2014 IOP Publishing Ltd.

Cardell S.D.,University of Campinas | Fuster-Sabater A.,Institute Tecnologias Fisicas Y Of La Informacion
Journal of Cellular Automata | Year: 2016

The self-shrinking generator is a non-linear cryptographic sequence generator designed to be used in stream cipher applications. In this work, its output sequence, the self-shrunken sequence, is computed as one of the output sequences of a linear model based on Cellular Automata. Such Automata are uniform, null, one-dimensional and use rules 102 or 60 for their computations. The linearity of these structures can be advantageous exploited to recover the complete selfshrunken sequence from a number of intercepted bits. Indeed, a Cellular Automata-based reconstruction procedure that is deterministic, does not need the knowledge of the LFSR characteristic polynomial and is performed exclusively by means of XOR operations has been proposed. © 2016 Old City Publishing, Inc.

PubMed | CINVESTAV and Institute Tecnologias Fisicas Y Of La Informacion
Type: Journal Article | Journal: International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group | Year: 2016

The aim of this study was to design an applicator for haemostasis usage needing lower acoustic intensities (<880W/cm(2)) than in previous devices intended for it, which is based on ultrasound propagation FEM modelling using a 2-MHz HIFU transducer.Acoustic field characterisation and numerical simulations in water were performed with and without the proposed applicator. Parameters such as form factor, ellipsoidal shape ratio, and Euclidean distance were used (among others) to compare simulated data with transducer measurements without applicator. A low density polyethylene cone was manufactured from geometries validated from acoustic field modelling. The hollow cone was filled with 10% polyacrylamide gel as a coupling medium with liver phantom or chicken liver. Focal temperature was measured with a thermocouple embedded in the phantom for 1-20W driving powers for 120s. Standing wave ratios (SWR) were used as coupling indexes. Ex vivo experimentation in chicken liver was made at 10-20W.Simulated acoustic patterns showed good concordance with measurements. Experimental focal distance was 20.720.24mm, while the simulated was 19.79mm (4% error). SWR at low power were: 2.01 with transducer emitting in air, 1.53 at applicator tip, and 1.35 after phantom placement. Average SWR at high power was 1.31. Similarity of percentages for data comparison in focal plane was over 60%. Maximum temperature measured at focus was 88.7C with 20W after 85s.Temperatures reached at focus suggest that this applicator has good efficiency, which notably reduces the power typically needed for haemostasis effect.

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