422 research outputs found

    Re-verification of a Lip Synchronization Algorithm using robust reachability

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    The timed automata formalism is an important model for specifying and analysing real-time systems. Robustness is the correctness of the model in the presence of small drifts on clocks or imprecision in testing guards. A symbolic algorithm for the analysis of the robustness of timed automata has been implemented. In this paper we re-analyse an industrial case lip synchronization protocol using the new robust reachability algorithm.This lip synchronization protocol is an interesting case because timing aspect are crucial for the correctness of the protocol. Several versions of the model are considered, with an ideal video stream, with anchored jitter, and with non-anchored jitter

    A Probabilistic Framework for Security Scenarios with Dependent Actions

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    This work addresses the growing need of performing meaningful probabilistic analysis of security. We propose a framework that integrates the graphical security modeling technique of attack–defense trees with probabilistic information expressed in terms of Bayesian networks. This allows us to perform probabilistic evaluation of attack–defense scenarios involving dependent actions. To improve the efficiency of our computations, we make use of inference algorithms from Bayesian networks and encoding techniques from constraint reasoning. We discuss the algebraic theory underlying our framework and point out several generalizations which are possible thanks to the use of semiring theory

    A Rewrite Approach for Pattern Containment -- Application to Query Evaluation on Compressed Documents

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    In this paper we introduce an approach that allows to handle the containment problem for the fragment XP(/,//,[ ],*) of XPath. Using rewriting techniques we define a necessary and sufficient condition for pattern containment. This rewrite view is then adapted to query evaluation on XML documents, and remains valid even if the documents are given in a compressed form, as dags

    Doctor of Philosophy

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    dissertationThe motivation for this work is the forward and inverse problem for magnetotellurics, a frequency domain electromagnetic remote-sensing geophysical method used in mineral, geothermal, and groundwater exploration. The dissertation consists of four papers. In the first paper, we prove the existence and uniqueness of a representation of any vector field in H(curl) by a vector lying in H(curl) and H(div). It allows us to represent electric or magnetic fields by another vector field, for which nodal finite element approximation may be used in the case of non-constant electromagnetic properties. With this approach, the system matrix does not become ill-posed for lowfrequency In the second paper, we consider hexahedral finite element approximation of an electric field for the magnetotelluric forward problem. The near-null space of the system matrix for low frequencies makes the numerical solution unstable in the air. We show that the proper solution may obtained by applying a correction on the null space of the curl. It is done by solving a Poisson equation using discrete Helmholtz decomposition. We parallelize the forward code on multicore workstation with large RAM. In the next paper, we use the forward code in the inversion. Regularization of the inversion is done by using the second norm of the logarithm of conductivity. The data space Gauss-Newton approach allows for significant savings in memory and computational time. We show the efficiency of the method by considering a number of synthetic inversions and we apply it to real data collected in Cascade Mountains. The last paper considers a cross-frequency interpolation of the forward response as well as the Jacobian. We consider Pade approximation through model order reduction and rational Krylov subspace. The interpolating frequencies are chosen adaptively in order to minimize the maximum error of interpolation. Two error indicator functions are compared. We prove a theorem of almost always lucky failure in the case of the right hand analytically dependent on frequency. The operator's null space is treated by decomposing the solution into the part in the null space and orthogonal to it

    Re-verification of a Lip Synchronization Protocol using Robust Reachability

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    The timed automata formalism is an important model for specifying and analysing real-time systems. Robustness is the correctness of the model in the presence of small drifts on clocks or imprecision in testing guards. A symbolic algorithm for the analysis of the robustness of timed automata has been implemented. In this paper, we re-analyse an industrial case lip synchronization protocol using the new robust reachability algorithm. This lip synchronization protocol is an interesting case because timing aspects are crucial for the correctness of the protocol. Several versions of the model are considered: with an ideal video stream, with anchored jitter, and with non-anchored jitter

    Correlating Al-Madinah constitution and the development of Islamic cities with the aspirations of sustainability

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    This dissertation examines how early Islamic cities urban planning, resulting from following the Islamic way of life through the foundation of Al-Madinah Constitution, have during times of sincere commitment of Muslims to Islam, naturally yielded aspired benevolent aspects of sustainability as a natural by-product of that commitment. It interprets the re-emergence, of aspirations for positive reform in a global to local sense, to be due to the ‘fitrah’, or natural creation of mankind

    DAG-Based Attack and Defense Modeling: Don't Miss the Forest for the Attack Trees

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    This paper presents the current state of the art on attack and defense modeling approaches that are based on directed acyclic graphs (DAGs). DAGs allow for a hierarchical decomposition of complex scenarios into simple, easily understandable and quantifiable actions. Methods based on threat trees and Bayesian networks are two well-known approaches to security modeling. However there exist more than 30 DAG-based methodologies, each having different features and goals. The objective of this survey is to present a complete overview of graphical attack and defense modeling techniques based on DAGs. This consists of summarizing the existing methodologies, comparing their features and proposing a taxonomy of the described formalisms. This article also supports the selection of an adequate modeling technique depending on user requirements

    The prevalence of metabolic syndrome in the north of Iran. An epidemiologic comparative study

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    Background and Objective: The metabolic syndrome (MetS) increases the risk of cardiovascular diseases and the main aim of this study is to explorer prevalence of it in the north of Iran with comparison of Turkman and non-Turkman ethnic groups in 2012. Material and Methods: This is a cross-sectional study that conducted on the 248 subjects aged 25-70 years (Turkman=88 and non-Turkman=160). Individuals were chosen randomly from 25 clusters. Waist circumference was measured with the subject standing at the end of normal breathing; blood pressure was measured in three times and 5 ml of venous blood drawn after 8-12 h fast in the morning for laboratory test. Biochemical analysis including fasting blood glucose, triglyceride and high-density lipoprotein (HDL) cholesterol was assayed using a commercially kit (Pars Azmoon, Karaj, Iran). ATP-III method and SPSS 16.0 software (Chicago II, USA) were used for diagnosis of MetS and for statistical analyzes, respectively. P-value < 0.05 considered statistically significant. Results: Compare to Turkman group, the mean of FBG (fasting blood glucose), triglyceride and waist circumference are 15.9 mg/dl, 30.2 mg/dl and 6.5 cm were more in non-Turkman group, respectively (P<0.05 for all). The Pearson's correlation coefficient is positive between age and MetS (r=0.287, P=0.01). Generally, MetS was common in 37.9 of subjects and it was 14.7 in non-Turkman more than in Turkman people (P=0.015). Prevalence rate of MetS in men and women was 29.7 and 43.5, respectively (P=0.001). Conclusion: In the north of Iran, the prevalence of MetS is high and it was in non-Turkman ethnic group more than in Turkman group and in women more than in men while gender differences only was shown in non-Turkman ethnic group
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