Étalonnage de la sûreté de fonctionnement des systèmes d’exploitation – Spécifications et mise en oeuvre

Les développeurs des systèmes informatiques, y compris critiques, font souvent appel à des systèmes d’exploitation sur étagère. Cependant, un mauvais fonctionnement d’un système d’exploitation peut avoir un fort impact sur la sûreté de fonctionnement du système global, d’où la nécessité de trouver des moyens efficaces pour caractériser sa sûreté de fonctionnement. Dans cette thèse, nous étudions l’étalonnage de la sûreté de fonctionnement des systèmes d’exploitation par rapport aux comportements défectueux de l’application. Nous spécifions les propriétés qu’un étalon de sûreté de fonctionnement doit satisfaire. Après, nous spécifions les mesures et la mise en oeuvre des trois étalons destinés à comparer la sûreté de fonctionnement de différents systèmes d’exploitation. Ensuite, nous développons les prototypes des trois étalons. Ces prototypes servent à comparer les différents systèmes d’exploitation des familles Windows et Linux, et pour montrer la satisfaction des propriétés identifiées. ABSTRACT : System developers are increasingly resorting to off-the-shelf operating systems, even in critical application domains. Any malfunction of the operating system may have a strong impact on the dependability of the global system. Therefore, it is important to make available information about the operating systems dependability. In our work, we aim to specify dependability benchmarks to characterize the operating systems with respect to the faulty behavior of the application. We specify three benchmarks intended for comparing the dependability of operating systems belonging to different families. We specify the set of measures and the procedures to be followed after defining the set of properties that a dependability benchmark should satisfy. After, we present implemented prototypes of these benchmarks. They are used to compare the dependability of operating systems belonging to Windows and Linux, and to show that our benchmarks satisfy the identified properties

Remote ischemic conditioning: from experimental observation to clinical application: report from the 8th Biennial Hatter Cardiovascular Institute Workshop

In 1993, Przyklenk and colleagues made the intriguing experimental observation that 'brief ischemia in one vascular bed also protects remote, virgin myocardium from subsequent sustained coronary artery occlusion' and that this effect '.... may be mediated by factor(s) activated, produced, or transported throughout the heart during brief ischemia/reperfusion'. This seminal study laid the foundation for the discovery of 'remote ischemic conditioning' (RIC), a phenomenon in which the heart is protected from the detrimental effects of acute ischemia/reperfusion injury (IRI), by applying cycles of brief ischemia and reperfusion to an organ or tissue remote from the heart. The concept of RIC quickly evolved to extend beyond the heart, encompassing inter-organ protection against acute IRI. The crucial discovery that the protective RIC stimulus could be applied non-invasively, by simply inflating and deflating a blood pressure cuff placed on the upper arm to induce cycles of brief ischemia and reperfusion, has facilitated the translation of RIC into the clinical setting. Despite intensive investigation over the last 20 years, the underlying mechanisms continue to elude researchers. In the 8th Biennial Hatter Cardiovascular Institute Workshop, recent developments in the field of RIC were discussed with a focus on new insights into the underlying mechanisms, the diversity of non-cardiac protection, new clinical applications, and large outcome studies. The scientific advances made in this field of research highlight the journey that RIC has made from being an intriguing experimental observation to a clinical application with patient benefit

DSL : crosstalk estimation techniques, and impact on DSM

DSL systems "Digitial Subscriber Line", take advantage of the long time not used high frequency bands of twisted pairs in order to transmit signals that may go up to 30 MHz. This band is much higher than the traditional voice band of 4 kHz. Going up in frequency allows DSL systems to transmit at a very high Bit-Rates (24 Mbps in ADSL2+, 100 Mbps for VDSL) , however it also poses various challenges. One of the challenges that may occur , is the increase of the interference between different lines, called crosstalk, at higher frequencies. Another drawback of using higher frequencies, is the fact that the direct channels of the twisted pairs are attenuated severly for long lines at higher frequencies. The attenuation of the direct channel gain for longer lines, coupled with crosstalk caused by other shorter lines in proximity would create a Near-Far problem in DSL systems when short and long lines are mixed together. Dynamic Spectrum Management or DSM was proposed to mitigate the effect of crosstalk on DSL systems. DSM exploits the information about the direct line channels, the crosstalk channels, and the ambient noise to improve the total system capacity. We may distinguish two DSM concepts: PSD coordination and Signal coordination. Both concepts necessitate the knowledge of crosstalk channels information, something that is not available under the current DSL systems. In this thesis we consider the application of DSM algorithms under practical and realistic conditions. In the first part we propose the Balanced Capacity concept as a possible solution for the Near-Far problem, then we proceed with the enhancement of several state of the art algorithms regarding DSM implementation. In the second part, we propose several practical estimation techniques for the crosstalk channel estimation. We start by estimating the crosstalk channel gain, which is sufficient for the application of PSD coordination algorithms, and then we proceed by the estimation of the total crosstalk channel which is required for the implementation of a full signal coordination. All of these estimation techniques are based on a passive or on a limited active observation of the DSL lines. Thus these estimators are practical, and can be used with the current DSL systems with minor modifications on the standards or on the users' modems.(COMU 3) -- UCL, 201

Conception d'un logiciel de programmation graphique des robots d'assemblage

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 77936 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

First comprehensive design of XLINK 1

doi: 10.6088/ijaser.0020101008 Abstract: In this article, we present the limitations of HTML hyperlink and how could be solve it by using a new XML based language XLINK. Till now there is neither clear specification nor implementation of thi

Étalonnage de la sûreté de fonctionnement des systèmes d'exploitation (spécifications et mise en oeuvre)

Les développeurs des systèmes informatiques, y compris critiques, font souvent appel à des systèmes d'exploitation sur étagère. Cependant, un mauvais fonctionnement d'un système d'exploitation peut avoir un fort impact sur la sûreté de fonctionnement du système global, d'où la nécessité de trouver des moyens efficaces pour caractériser sa sûreté de fonctionnement. Dans cette thèse, nous étudions l'étalonnage de la sûreté de fonctionnement des systèmes d'exploitation par rapport aux comportements défectueux de l'application. Nous spécifions les propriéte s qu'un étalon de sûreté de fonctionnement doit satisfaire. Après, nous spécifions les mesures et la mise en oeuvre des trois étalons destinés à comparer la sûreté de fonctionnement de différents systèmes d'exploitation. Ensuite, nous développons les prototypes des trois étalons. Ces prototypes servent à comparer les différents systèmes d'exploitation des familles Windows et Linux, et pour montrer la satisfaction des propriétés identifiées.System developers are increasingly resorting to off-the-shelf operating systems, even in critical application domains. Any malfunction of the operating system may have a strong impact on the dependability of the global system. Therefore, it is important to make available information about the operating systems dependability. In our work, we aim to specify dependability benchmarks to characterize the operating systems with respect to the faulty behavior of the application. We specify three benchmarks intended for comparing the dependability of operating systems belonging to different families. We specify the set of measures and the procedures to be followed after defining the set of properties that a dependability benchmark should satisfy. After, we present implemented prototypes of these benchmarks. They are used to compare the dependability of operating systems belonging to Windows and Linux, and to show that our benchmarks satisfy the identified properties.TOULOUSE-ENSEEIHT (315552331) / SudocSudocFranceF

MINIMIZING MOBILES COMMUNICATION TIME USING MODIFIED BINARY EXPONENTIAL BACKOFF ALGORITHM

ABSTRAC

Time Domain Channel Estimation in OFDM Systems Using limited number of Pilot Tones

This paper deals with the time domain estimation of OFDM channels in the case of a limited number of pilot tones. In such situations, time domain estimation suffers from an ill conditioned sample matrix which render the Least Square (LS) algorithm non efficient. To improve the estimation procedure, two algorithms are proposed. The first algorithm improves the conditioning of the LS matrix by adding a corrective term or penalization factor to the LS pseudo inverse matrix. The second algorithm tries to partially remove the effect of the penalization factor iteratively. Computational results are provided for the case of crosstalk channel estimation in DSL system these results show the effectiveness of the different methods