Solutions for IPv6-based mobility in the EU project MobyDick

Proceedings of the WTC 2002, 18th World Telecommunications Congress, Paris, France, 22 -27 September, 2002.Mobile Internet technology is moving towards a packet-based or, more precisely, IPv6-based network. Current solutions on Mobile IPv6 and other related QoS and AAA matters do not offer the security and quality users have come to take for granted. The EU IST project Moby Dick has taken on the challenge of providing a solution that integrates QoS, mobility and AAA in a heterogeneous access environment. This paper focuses on the mobility part of the project, describes and justifies the handover approach taken, shows how QoS-aware and secure handover is achieved, and introduces the project's paging concept. It shows that a transition to a fully integrated IP-RAN and IP-Backbone has become a distinct option for the future.Publicad

The Corepressor NCoR1 Antagonizes PGC-1α and Estrogen-Related Receptor α in the Regulation of Skeletal Muscle Function and Oxidative Metabolism

Skeletal muscle exhibits a high plasticity and accordingly can quickly adapt to different physiological and pathological stimuli by changing its phenotype largely through diverse epigenetic mechanisms. The nuclear receptor corepressor 1 (NCoR1) has the ability to mediate gene repression; however, its role in regulating biological programs in skeletal muscle is still poorly understood. We therefore studied the mechanistic and functional aspects of NCoR1 function in this tissue. NCoR1 muscle-specific knockout mice exhibited a 7.2% higher peak oxygen consumption (VO(2peak)), a 11% reduction in maximal isometric force, and increased ex vivo fatigue resistance during maximal stimulation. Interestingly, global gene expression analysis revealed a high overlap between the effects of NCoR1 deletion and peroxisome proliferator-activated receptor gamma (PPARγ) coactivator 1α (PGC-1α) overexpression on oxidative metabolism in muscle. Importantly, PPARβ/δ and estrogen-related receptor α (ERRα) were identified as common targets of NCoR1 and PGC-1α with opposing effects on the transcriptional activity of these nuclear receptors. In fact, the repressive effect of NCoR1 on oxidative phosphorylation gene expression specifically antagonizes PGC-1α-mediated coactivation of ERRα. We therefore delineated the molecular mechanism by which a transcriptional network controlled by corepressor and coactivator proteins determines the metabolic properties of skeletal muscle, thus representing a potential therapeutic target for metabolic diseases

Trajectory planning and tracking via MPC for transient control of liquid-propellant rocket engines

International audienceThe new scenarios associated with launchers reusability force the enhancement of control algorithms for their liquid-propellant rocket engines. The transient phases of these engines are generally executed in open loop. The goal of this paper is to improve the control performance and robustness throughout the fully continuous phase of the start-up transient of a generic gas-generator cycle. The controller has to guarantee an accurate tracking in terms of combustion-chamber pressure and chambers mixture ratios, as well as to satisfy a set of hard operational constraints. The selected strategy comprises a nonlinear preprocessor and a linearised MPC (Model-Predictive Control) controller, making use of nonlinear state-space models of the engine. The former plans the reference trajectory of states and control, which is tracked by the latter. Control goals are attained with sufficient accuracy while verifying constraints within the desired throttling range. Robustness to internal parameters variations is considered in the MPC controller by means of an epigraph formulation of the minimax robust optimisation problem, where a finite set of parameter-variation scenarios is treated

Robust Transient Control of Reusable Liquid-Propellant Rocket Engines

International audienceThe current trend towards a more affordable access to space is generally materialising in reusable launchers and engines. From the control perspective, these reusable liquid-propellant rocket engines (LPRE) imply more demanding robustness requirements than expendable ones, mainly because of their multi-restart and thrust-modulation capabilities. Classically, the control system handles LPRE operation at a finite set of predefined points. That approach reduces their throttability domain to a restricted interval in which they are designed to be safe in nominal conditions. Moreover, the operation of their transient phases, which have a great impact on the duration of engine life, is not robust to the possible engine evolution. Hence, the goal of this work is to develop a control loop which is adapted to the whole set of operating phases, transient and steady-state, and which is robust to internal parametric variations. Several blocks have been assembled to constitute the control loop: engine simulation, reference generation and several controllers. First, simulators representative of the gas-generator-cycle (GG) Vulcain 1 and PROMETHEUS engines were built. The purely thermodynamic modelling of the cycle was subsequently adapted to the control framework, obtaining a nonlinear state-space model. The available actuators are continuously controllable valves, binary igniters and binary starters. These actuators are related to discrete events in transient phases. Regarding the start-up operation, the igniter, starter and valves are activated during the first seconds. Up from the end of those activations, the whole system behaves in a fully continuous way. Hence, a different control strategy is proposed for each sub-phase. For the first and discrete sub-phase, a discrete optimisation of events timing is proposed, in which the time differences between events are adapted according to operation criteria and constraints. This trajectory planning, still under implementation, is to be performed off-line. The subsequent continuous sub-phase is feedback controlled to track pre-computed reference trajectories. Apart from the start-up, throttling scenarios also present a dedicated end-state-tracking algorithm. A model-based control method, Model Predictive Control, has been applied in a linearised manner with robustness guarantees to all these scenarios, in which a set of hard state and control constraints must be respected. Tracking of pressure (thrust) and mixture-ratio operating points within the design envelope is achieved in simulation along the continuous sub-phase while respecting constraints. Robustness to variations of the parameters, which are checked to be predominant according to analyses, is also demonstrated

An MPC Approach to Transient Control of Liquid-Propellant Rocket Engines

International audienceThe current context of launchers reusability requires the improvement of control algorithms for their liquid-propellant rocket engines. Their transient phases are generally still performed in open loop. In this paper, it is aimed at enhancing the control performance and robustness during the fully continuous phase of the start-up transient of a generic gas-generator cycle. The main control goals concern end-state tracking in terms of combustion-chamber pressure and chambers mixture ratios, as well as the verification of a set of hard operational constraints. A controller based on a nonlinear preprocessor and on linear MPC (Model-Predictive Control) has been synthesised, making use of nonlinear state-space models of the engine. The former generates the full-state reference to be tracked while the latter achieves the aforementioned goals with sufficient accuracy and verifying constraints for the required pressure levels. Robustness considerations are included in the MPC algorithm via an epigraph formulation of the minimax robust optimisation problem, where a finite set of perturbation scenarios is considered

Primer yacimiento con huellas de dinosaurio del Cretácico Inferior del Alto Atlas Occidental (Marruecos)

Eight vertebrate trackways were found near the Imi-n-Tanout village, in the proximity of the two Marrakesh-Agadir roads: three theropod, two sauropods trackways; and three of an unknown bipedal trackmaker. The outcrop is the first Early Cretaceous dinosaur tracksite found in Morocco and the second (Barremian-early Aptian) site of Africa. This preliminary report provides morphometric and biomorphic descriptions of the footprints and trackways, their classification, and an interpretation on the formation of the two “pes-only” sauropod trackwaysSe han descubierto ocho rastrilladas de vertebrados cerca del pueblo de Imi-n-Tanout, en la vecindad de las dos carreteras que unen Marrakesh y Agadir. El contenido icnológico incluye: tres rastrilladas terópodas; dos de saurópodos; y tres de icnopoyetas bípedos no identificados. Es el primer yacimiento encontrado con huellas de dinosaurio del Cretácico Inferior de Marruecos y el segundo (Barremiense-Aptiense inferior) del continente africano. En el trabajo se proporcionan los datos morfométricos y biomórficos de las icnitas, su clasificación y una interpretación sobre la génesis de las dos rastrilladas saurópodas “solo de pies

Shape: automatic conformation prediction of carbohydrates using a genetic algorithm

<p>Abstract</p> <p>Background</p> <p>Detailed experimental three dimensional structures of carbohydrates are often difficult to acquire. Molecular modelling and computational conformation prediction are therefore commonly used tools for three dimensional structure studies. Modelling procedures generally require significant training and computing resources, which is often impractical for most experimental chemists and biologists. <monospace>Shape</monospace> has been developed to improve the availability of modelling in this field.</p> <p>Results</p> <p>The <monospace>Shape</monospace> software package has been developed for simplicity of use and conformation prediction performance. A trivial user interface coupled to an efficient genetic algorithm conformation search makes it a powerful tool for automated modelling. Carbohydrates up to a few hundred atoms in size can be investigated on common computer hardware. It has been shown to perform well for the prediction of over four hundred bioactive oligosaccharides, as well as compare favourably with previously published studies on carbohydrate conformation prediction.</p> <p>Conclusion</p> <p>The <monospace>Shape</monospace> fully automated conformation prediction can be used by scientists who lack significant modelling training, and performs well on computing hardware such as laptops and desktops. It can also be deployed on computer clusters for increased capacity. The prediction accuracy under the default settings is good, as it agrees well with experimental data and previously published conformation prediction studies. This software is available both as open source and under commercial licenses.</p

An algorithm that constructs irreducible triangulations of once-punctured surfaces

A triangulation of a surface is irreducible if there is no edge whose contraction produces another triangulation of the surface. In this work we propose an algorithm that constructs the set of irreducible triangulations of any surface with precisely one boundary component.Plan Andaluz de Investigación (Junta de Andalucía