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Real-time Target Tracking of Soft Tissues in 3D Ultrasound Images Based on Robust Visual Information and Mechanical Simulation
No full textInternational audienceIn this paper, we present a real-time approach that allows tracking deformable structures in 3D ultrasound sequences. Our method consists in obtaining the target displacements by combining robust dense motion estimation and mechanical model simulation. We perform evaluation of our method through simulated data, phantom data, and real-data. Results demonstrate that this novel approach has the advantage of providing correct motion estimation regarding different ultrasound shortcomings including speckle noise, large shadows and ultrasound gain variation. Furthermore, we show the good performance of our method with respect to state-of-the-art techniques by testing on the 3D databases provided by MICCAI CLUST'14 and CLUST'15 challenges
Designing and proving an EMV-compliant payment protocol for mobile devices
No full textInternational audienceWe devise a payment protocol that can be securely used on mobile devices, even infected by malicious applications. Our protocol only requires a light use of Secure Elements, which significantly simplify certification procedures and protocol maintenance. It is also fully compatible with the EMV SDA protocol and allows off-line payments for the users. We provide a formal model and full security proofs of our protocol using the TAMARIN prover
Intruder deducibility constraints with negation. Decidability and application to secured service compositions
No full textInternational audienceWe consider a problem of automated orchestration of security-aware services under additional constraints. The problem of finding a mediator to compose secured services has been reduced in previous works to the problem of solving deducibility constraints similar to those employed for cryptographic protocol analysis. We extend in this paper the mediator synthesis procedure (i.e. a solution for the orchestration problem) by allowing additional non-disclosure policies that express the fact that some data is not accessible to the mediator at a given point of its execution. We present a decision procedure that answers the question whether a mediator satisfying these policies can be effectively synthesized. The approach presented in this work extends the constraint solving procedure for cryptographic protocol analysis in a significant way as to be able to handle negation of deducibility constraints. It applies to all subterm convergent theories and therefore covers several interesting theories in formal security analysis including encryption, hashing, signature and pairing; it is also expressive enough for some RBAC policies. A variant of this procedure for Dolev Yao theory has been implemented in Cl-Atse, a protocol analysis tool based on constraint solving
Design Methodology of a Printed WPT System for HF-Band Mid-Range Applications Considering Human Safety Regulations
No full textInternational audienceA methodology for the design of printed magnetically coupled resonant wireless power-transfer (WPT) systems is proposed. The design methodology aims at a well-matched system with a maximized power-transfer efficiency for mid-range applications. The system consists of two identical resonant coils driven by high-quality factor loops. The proposed design criteria allows obtaining maximum achievable transfer efficiency and impedance matching at any defined distance without any external matching circuits connected to the driven loops. For validation purposes, a printed WPT system at 10 MHz is fabricated targeting 1-m distance between the transmitting and receiving sides. Its performances in terms of reflection and transmission coefficients, as well as in terms of generated electric and magnetic fields, have been characterized numerically and experimentally. The impact of human body presence on the system has also been investigated observing the splitting in two frequencies of the common resonant frequency of the coils. A dosimetric study has been conducted using a detailed high-resolution anatomical human body model and considering E99, J1 cm2, and specific absorption rate (SAR) (local and whole body averaged SAR) as exposure metrics. It has been observed that peak exposure levels appear in different tissues depending on the body location. Compliance with the international commission on nonionizing radiation protection (ICNIRP) reference level as well as basic restrictions has been studied followed by computing the maximum allowable input power. It has been found that, with the body located 1 m away from the transmitting coil, the maximum allowable input power satisfying E99 is in the order of MW, whereas it reduces to tens of kilowatt when considering SAR and J1 cm2. The latter has been noticed to be the most restrictive dosimetric quantity. © 2016 IEEE
How to Explain Modern Security Concepts to your Children
No full textInternational audienceAt the main cryptography conference CRYPTO in 1989, Quisquater et al. published a paper showing how to explain the complex notion of zero-knowledge proof in a simpler way that children can understand. In the same line of work, we present simple and intuitive explanations of various modern security concepts and technologies, including symmetric encryption, public key encryption, homomorphic encryption, intruder models (CPA, CCA1, CCA2) and security properties (OW, IND, NM). The explanations given in this paper may also serve in demystifying such complex security notions for non-expert adults
Construction of parametric barrier functions for dynamical systems using interval analysis
No full textInternational audienceRecently, barrier certificates have been introduced to prove the safety of continuous or hybrid dynamical systems. A barrier certificate needs to exhibit some barrier function, which partitions the state space in two subsets: the safe subset in which the state can be proved to remain and the complementary subset containing some unsafe region. This approach does not require any reachability analysis, but needs the computation of a valid barrier function, which is difficult when considering general nonlinear systems and barriers. This paper presents a new approach for the construction of barrier functions for nonlinear dynamical systems. The proposed technique searches for the parameters of a parametric barrier function using interval analysis. Complex dynamics can be considered without needing any relaxation of the constraints to be satisfied by the barrier function
Power evaluation of asymptotic tests for comparing two binomial proportions to detect direct and indirect association in large-scale studies
No full textInternational audienceAsymptotic tests are commonly used for comparing two binomial proportions when the sample size is sufficiently large. However, there is no consensus on the most powerful test. In this paper, we clarify this issue by comparing the power functions of three popular asymptotic tests: the Pearson’s χ2 test, the likelihood-ratio test and the odds-ratio based test. Considering Taylor decompositions under local alternatives, the comparisons lead to recommendations on which test to use in view of both the experimental design and the nature of the investigated signal. We show that when the design is balanced between the two binomials, the three tests are equivalent in terms of power. However, when the design is unbalanced, differences in power can be substantial and the choice of the most powerful test also depends on the value of the parameters of the two compared binomials. We further investigated situations where the two binomials are not compared directly but through tag binomials. In these cases of indirect association, we show that the differences in power between the three tests are enhanced with decreasing values of the parameters of the tag binomials. Our results are illustrated in the context of genetic epidemiology where the analysis of genome-wide association studies provides insights regarding the low power for detecting rare variants
BIGnav: Bayesian Information Gain for Guiding Multiscale Navigation
No full textInternational audienceThis paper introduces BIGnav, a new multiscale navigation technique based on Bayesian Experimental Design where the criterion is to maximize the information-theoretic concept of mutual information, also known as information gain. Rather than simply executing user navigation commands, BIGnav interprets user input to update its knowledge about the user's intended target. Then it navigates to a new view that maximizes the information gain provided by the user's expected subsequent input. We conducted a controlled experiment demonstrating that BIGnav is significantly faster than conventional pan and zoom and requires fewer commands for distant targets, especially in non-uniform information spaces. We also applied BIGnav to a realistic application and showed that users can navigate to highly probable points of interest on a map with only a few steps. We then discuss the tradeoffs of BIGnav—including efficiency vs. increased cognitive load—and its application to other interaction tasks
Spectro-Polarimetry of Fine-Grained Ice and Dust Surfaces Measured in the Laboratory to Study Solar System Objects and Beyond
No full textInternational audienceThe polarization of the light is very sensitive to the size, morphology, porosity and composition of the scattering particles. As a consequence, polarimetric observations could significantly complement observations performed in total light intensity, providing additional constraints to interpret remote sensing observations of Solar System and extra-solar objects. This presentation will focus on measurements performed in the laboratory on carefully characterized surface samples, providing reference data that can be used to test theoretical models and predict or interpret spectro-polarimetric observations.Using methods developed in the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern, we produce well-characterized and reproducible surfaces made of water ice particles having different grain sizes and porosities, as well as mineral/organic dusts, pure or mixed together, as analogues of planetary or small bodies surfaces. These surface samples are illuminated with a randomly polarized light source simulating the Sun. The polarization of their scattered light is measured at multiple phase angles and wavelengths, allowing to study the shape of the polarimetric phase curves and their spectral dependence, with two recently developed setups:The POLarimeter for Icy Samples (POLICES), at the University of Bern, allows the measurement of the weak polarization of ice surfaces from 400 to 800 nm, with direct application to icy satellites. Using a precision Stokes polarimeter, this setup is also used to study the spectral variations of circular polarization in the light scattered by biotic versus abiotic surfaces.The Spectrogonio radiometer with cHanging Angles for Detection Of Weak Signals (SHADOWS), at IPAG (University of Grenoble Alpes), measures linear polarization spectra from 0.35 to 5 μm in the light scattered by dark meteorite powders or icy samples, with application to primitive objects of the Solar System (asteroids, comets)
