5 resultados para Controllability of systems

em Universidade Complutense de Madrid


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Reconfigurable HW can be used to build a hardware multitasking system where tasks can be assigned to the reconfigurable HW at run-time according to the requirements of the running applications. Normally the execution in this kind of systems is controlled by an embedded processor. In these systems tasks are frequently represented as subtask graphs, where a subtask is the basic scheduling unit that can be assigned to a reconfigurable HW. In order to control the execution of these tasks, the processor must manage at run-time complex data structures, like graphs or linked list, which may generate significant execution-time penalties. In addition, HW/SW communications are frequently a system bottleneck. Hence, it is very interesting to find a way to reduce the run-time SW computations and the HW/SW communications. To this end we have developed a HW execution manager that controls the execution of subtask graphs over a set of reconfigurable units. This manager receives as input a subtask graph coupled to a subtask schedule, and guarantees its proper execution. In addition it includes support to reduce the execution-time overhead due to reconfigurations. With this HW support the execution of task graphs can be managed efficiently generating only very small run-time penalties.

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We present and formalize a concept of synchronous product for rewrite systems, and also a corresponding concept for general transition systems, used as semantics for the former. A series of examples shows their practical usefulness: for the strategic control of systems, and for modular specification and verification.

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We investigate the critical properties of the four-state commutative random permutation glassy Potts model in three and four dimensions by means of Monte Carlo simulations and a finite-size scaling analysis. By using a field programmable gate array, we have been able to thermalize a large number of samples of systems with large volume. This has allowed us to observe a spin-glass ordered phase in d=4 and to study the critical properties of the transition. In d=3, our results are consistent with the presence of a Kosterlitz-Thouless transition, but also with different scenarios: transient effects due to a value of the lower critical dimension slightly below 3 could be very important.

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In the last decades accumulated clinical evidence has proven that intra-operative radiation therapy (IORT) is a very valuable technique. In spite of that, planning technology has not evolved since its conception, being outdated in comparison to current state of the art in other radiotherapy techniques and therefore slowing down the adoption of IORT. RADIANCE is an IORT planning system, CE and FDA certified, developed by a consortium of companies, hospitals and universities to overcome such technological backwardness. RADIANCE provides all basic radiotherapy planning tools which are specifically adapted to IORT. These include, but are not limited to image visualization, contouring, dose calculation algorithms-Pencil Beam (PB) and Monte Carlo (MC), DVH calculation and reporting. Other new tools, such as surgical simulation tools have been developed to deal with specific conditions of the technique. Planning with preoperative images (preplanning) has been evaluated and the validity of the system being proven in terms of documentation, treatment preparation, learning as well as improvement of surgeons/radiation oncologists (ROs) communication process. Preliminary studies on Navigation systems envisage benefits on how the specialist to accurately/safely apply the pre-plan into the treatment, updating the plan as needed. Improvements on the usability of this kind of systems and workflow are needed to make them more practical. Preliminary studies on Intraoperative imaging could provide an improved anatomy for the dose computation, comparing it with the previous pre-plan, although not all devices in the market provide good characteristics to do so. DICOM.RT standard, for radiotherapy information exchange, has been updated to cover IORT particularities and enabling the possibility of dose summation with external radiotherapy. The effect of this planning technology on the global risk of the IORT technique has been assessed and documented as part of a failure mode and effect analysis (FMEA). Having these technological innovations and their clinical evaluation (including risk analysis) we consider that RADIANCE is a very valuable tool to the specialist covering the demands from professional societies (AAPM, ICRU, EURATOM) for current radiotherapy procedures.

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A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. EChO—the Exoplanet Characterisation Observatory—is a mission concept specifically geared for this purpose. EChO will provide simultaneous, multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures. The use of passive cooling, few moving parts and well established technology gives a low-risk and potentially long-lived mission. EChO will build on observations by Hubble, Spitzer and ground-based telescopes, which discovered the first molecules and atoms in exoplanetary atmospheres. However, EChO’s configuration and specifications are designed to study a number of systems in a consistent manner that will eliminate the ambiguities affecting prior observations. EChO will simultaneously observe a broad enough spectral region—from the visible to the mid-infrared—to constrain from one single spectrum the temperature structure of the atmosphere, the abundances of the major carbon and oxygen bearing species, the expected photochemically-produced species and magnetospheric signatures. The spectral range and resolution are tailored to separate bands belonging to up to 30 molecules and retrieve the composition and temperature structure of planetary atmospheres. The target list for EChO includes planets ranging from Jupiter-sized with equilibrium temperatures T_ eq up to 2,000 K, to those of a few Earth masses, with T _eq \u223c 300 K. The list will include planets with no Solar System analog, such as the recently discovered planets GJ1214b, whose density lies between that of terrestrial and gaseous planets, or the rocky-iron planet 55 Cnc e, with day-side temperature close to 3,000 K. As the number of detected exoplanets is growing rapidly each year, and the mass and radius of those detected steadily decreases, the target list will be constantly adjusted to include the most interesting systems. We have baselined a dispersive spectrograph design covering continuously the 0.4–16 μm spectral range in 6 channels (1 in the visible, 5 in the InfraRed), which allows the spectral resolution to be adapted from several tens to several hundreds, depending on the target brightness. The instrument will be mounted behind a 1.5 m class telescope, passively cooled to 50 K, with the instrument structure and optics passively cooled to \u223c45 K. EChO will be placed in a grand halo orbit around L2. This orbit, in combination with an optimised thermal shield design, provides a highly stable thermal environment and a high degree of visibility of the sky to observe repeatedly several tens of targets over the year. Both the baseline and alternative designs have been evaluated and no critical items with Technology Readiness Level (TRL) less than 4–5 have been identified. We have also undertaken a first-order cost and development plan analysis and find that EChO is easily compatible with the ESA M-class mission framework.