Parallelization of cycle-based logic simulation

Verification of digital circuits by Cycle-based simulation can be performed in parallel. The parallel implementation requires two phases: the compilation phase, that sets up the data needed for the execution of the simulation, and the simulation phase, that consists in executing the parallel simulation of the considered circuit for a certain number of cycles. During the early phase of design, compilation phase has to be repeated each time a bug is found. Thus, if the time of the compilation phase is too high, the advantages stemming from the parallel approach may be lost. In this work we propose an effective version of the compilation phase and compute the corresponding execution time. We also analyze the percentage of execution time required by the different steps of the compilation phase for a set of literature benchmarks. Further, we implemented the simulation phase exploiting the GPU architecture, and we computed the execution times for a set of benchmarks obtaining values comparable with literature ones. Finally, we implemented the sequential version of the Cycle-based simulation in such a way that the execution time is optimized. We used the sequential values to compute the speedup of the parallel version for the considered set of benchmarks

The benefit of high-conductivity materials in film cooled turbine nozzles

This study presents an experimental and numerical investigation of the beneficial effect of higher conductivity materials in HP turbine nozzles. Most of the literature studies focus on the maximum temperature that a nozzle can withstand, whereas the effect of thermal gradients is often neglected. However thermal gradients have higher influence on the life of the components and they have to be given careful consideration. In this work it is shown that thermal gradients are reduced by using high conductivity materials and, as a consequence, the nozzles life is appreciably increased. A representative film cooled leading edge with an internal impingement plate was studied experimentally at Texas AM University. Two materials were used, namely polycarbonate and stainless steel, in order to highlight the impact of conduction on coolant effectiveness. Numerically conjugate heat transfer simulations have been carried out with an in house solver to analyse in detail the impact of conduction and internal convection. Both experimental and numerical results show that by increasing the conductivity in the solid region, the thermal gradients are strongly reduced. Numerically it is shown that using inserts of nickel-aluminide alloys in nozzles may reduce the thermal gradients from 3 to 4 times if compared to nowadays design. © 2012 Elsevier Inc

Tras la pista de lo libertario

Es un hecho bastante común que al momento de abordar la cuestión libertaria, ya sea al nivel de la teoría como en el del sentido común, se la piense como un fenómeno capaz de sobrepasar todo tipo de coto u obstáculo que implique algún recorte en su expresión (sea del orden de lo material, político, cultural, moral o de cualquier otra especie): una especie de absoluto que por su fuerza irrefrenable se colocaría más cerca de lo utópico, más específicamente, como una ensoñación. Esa es una postura susceptible de adoptar diferentes valoraciones axiológicas, siendo el asumirla como uno de los mayores males que encuentran los hombres que quieren vivir en sociedad (de libertino o el de libertinaje) uno de las más recurrentes: lo libertario acaba con los pactos, los acuerdos, las leyes, y demás instituciones que rigen a las sociedades modernas. Obviamente, es una acepción que no contempla lo libertario como posibilidad efectiva de destrucción pero de ordenamientos que generan y reproducen desigualdades, dominaciones, marginalidad y exclusión. Y es tal perspectiva la que aquí nos interesa desarrollar. (Párrafo extraído del texto a modo de resumen)Mesa 3: El esquivo objeto de la ideologíaFacultad de Humanidades y Ciencias de la Educació

Anytime system level verification via parallel random exhaustive hardware in the loop simulation

System level verification of cyber-physical systems has the goal of verifying that the whole (i.e., software + hardware) system meets the given specifications. Model checkers for hybrid systems cannot handle system level verification of actual systems. Thus, Hardware In the Loop Simulation (HILS) is currently the main workhorse for system level verification. By using model checking driven exhaustive HILS, System Level Formal Verification (SLFV) can be effectively carried out for actual systems. We present a parallel random exhaustive HILS based model checker for hybrid systems that, by simulating all operational scenarios exactly once in a uniform random order, is able to provide, at any time during the verification process, an upper bound to the probability that the System Under Verification exhibits an error in a yet-to-be-simulated scenario (Omission Probability). We show effectiveness of the proposed approach by presenting experimental results on SLFV of the Inverted Pendulum on a Cart and the Fuel Control System examples in the Simulink distribution. To the best of our knowledge, no previously published model checker can exhaustively verify hybrid systems of such a size and provide at any time an upper bound to the Omission Probability

Simulator Semantics for System Level Formal Verification

Many simulation based Bounded Model Checking approaches to System Level Formal Verification (SLFV) have been devised. Typically such approaches exploit the capability of simulators to save computation time by saving and restoring the state of the system under simulation. However, even though such approaches aim to (bounded) formal verification, as a matter of fact, the simulator behaviour is not formally modelled and the proof of correctness of the proposed approaches basically relies on the intuitive notion of simulator behaviour. This gap makes it hard to check if the optimisations introduced to speed up the simulation do not actually omit checking relevant behaviours of the system under verification. The aim of this paper is to fill the above gap by presenting a formal semantics for simulators.Comment: In Proceedings GandALF 2015, arXiv:1509.0685

Push & Pull: autonomous deployment of mobile sensors for a complete coverage

Mobile sensor networks are important for several strategic applications devoted to monitoring critical areas. In such hostile scenarios, sensors cannot be deployed manually and are either sent from a safe location or dropped from an aircraft. Mobile devices permit a dynamic deployment reconfiguration that improves the coverage in terms of completeness and uniformity. In this paper we propose a distributed algorithm for the autonomous deployment of mobile sensors called Push&Pull. According to our proposal, movement decisions are made by each sensor on the basis of locally available information and do not require any prior knowledge of the operating conditions or any manual tuning of key parameters. We formally prove that, when a sufficient number of sensors are available, our approach guarantees a complete and uniform coverage. Furthermore, we demonstrate that the algorithm execution always terminates preventing movement oscillations. Numerous simulations show that our algorithm reaches a complete coverage within reasonable time with moderate energy consumption, even when the target area has irregular shapes. Performance comparisons between Push&Pull and one of the most acknowledged algorithms show how the former one can efficiently reach a more uniform and complete coverage under a wide range of working scenarios.Comment: Technical Report. This paper has been published on Wireless Networks, Springer. Animations and the complete code of the proposed algorithm are available for download at the address: http://www.dsi.uniroma1.it/~novella/mobile_sensors

Mauricio Beuchot, La semiótica. Teorías del signo y el lenguaje en la historia, México, Fondo de Cultura Económica, 2004, 208 pp.

Fil: Massini Correas, Carlos I.

On minimising the maximum expected verification time

Cyber Physical Systems (CPSs) consist of hardware and software components. To verify that the whole (i.e., software + hardware) system meets the given specifications, exhaustive simulation-based approaches (Hardware In the Loop Simulation, HILS) can be effectively used by first generating all relevant simulation scenarios (i.e., sequences of disturbances) and then actually simulating all of them (verification phase). When considering the whole verification activity, we see that the above mentioned verification phase is repeated until no error is found. Accordingly, in order to minimise the time taken by the whole verification activity, in each verification phase we should, ideally, start by simulating scenarios witnessing errors (counterexamples). Of course, to know beforehand the set of such scenarios is not feasible. In this paper we show how to select scenarios so as to minimise the Worst Case Expected Verification Tim

Taming transgression: Dionysos in the arts of the modern era

The topic of my research is the irrational and the ways it was accommodated through the visual arts of the modern era. In particular, I explore this theme through the relationship between Dionysos and Apollo. Ever since Nietzsche's 'Die Geburt der Tragodie' (1872), the polarity of the two gods has been codified in Western culture. Yet while their discrepancy as opposites has been widely discussed, they are two sides of the same coin, sharing similar traits since Antiquity. Beginning with an introduction on the cultural climate of the nineteenth-century, I argue that Nietzsche's principles had been anticipated by the exponents of German Romanticism and found earlier sources in the Humanism of fifteenth-century Italy, when Plato's writings in praise of 'madness' were rediscovered. While investigating significant aspects of Western cultural heritage, I trace the sources of Nietzsche's ideas, confronting these with examples from the visual arts. To this end, I first re-consider the ancient Dionysos and his transformation in the Middle Ages. I then analyse which aspects of the god were favoured in the Renaissance and which Dionysian narratives were re-produced. Within this framework, I assess the multifaceted character of the god and the meanings he acquired according to different periods, places and requirements. `Bacchus, id est vinum' recites a popular formula, but from Michelangelo to Caravaggio and beyond, this was not the only Dionysian guise to be known in the modern era. While often represented as a merrymaking god of nature, either alone or participating in Bacchanals and his Triumphs, darker aspects could be chosen to represent his world. It is the madness and disorder, as well as the reasons for their revelation (or omission) in specific contexts that I explore, in the belief that they provided the roots for Nietzsche's dualistic formulations and many a modern coniunctio oppositorum