486 research outputs found
IMITATOR II: A Tool for Solving the Good Parameters Problem in Timed Automata
We present here Imitator II, a new version of Imitator, a tool implementing
the "inverse method" for parametric timed automata: given a reference valuation
of the parameters, it synthesizes a constraint such that, for any valuation
satisfying this constraint, the system behaves the same as under the reference
valuation in terms of traces, i.e., alternating sequences of locations and
actions. Imitator II also implements the "behavioral cartography algorithm",
allowing us to solve the following good parameters problem: find a set of
valuations within a given bounded parametric domain for which the system
behaves well. We present new features and optimizations of the tool, and give
results of applications to various examples of asynchronous circuits and
communication protocols.Comment: In Proceedings INFINITY 2010, arXiv:1010.611
Translating UML State Machines to Coloured Petri Nets Using Acceleo: A Report
UML state machines are widely used to specify dynamic systems behaviours.
However its semantics is described informally, thus preventing the application
of model checking techniques that could guarantee the system safety. In a
former work, we proposed a formalisation of non-concurrent UML state machines
using coloured Petri nets, so as to allow for formal verification. In this
paper, we report our experience to implement this translation in an automated
manner using the model-to-text transformation tool Acceleo. Whereas Acceleo
provides interesting features that facilitated our translation process, it also
suffers from limitations uneasy to overcome.Comment: In Proceedings ESSS 2014, arXiv:1405.055
Parametric Schedulability Analysis of Fixed Priority Real-Time Distributed Systems
Parametric analysis is a powerful tool for designing modern embedded systems,
because it permits to explore the space of design parameters, and to check the
robustness of the system with respect to variations of some uncontrollable
variable. In this paper, we address the problem of parametric schedulability
analysis of distributed real-time systems scheduled by fixed priority. In
particular, we propose two different approaches to parametric analysis: the
first one is a novel technique based on classical schedulability analysis,
whereas the second approach is based on model checking of Parametric Timed
Automata (PTA).
The proposed analytic method extends existing sensitivity analysis for single
processors to the case of a distributed system, supporting preemptive and
non-preemptive scheduling, jitters and unconstrained deadlines. Parametric
Timed Automata are used to model all possible behaviours of a distributed
system, and therefore it is a necessary and sufficient analysis. Both
techniques have been implemented in two software tools, and they have been
compared with classical holistic analysis on two meaningful test cases. The
results show that the analytic method provides results similar to classical
holistic analysis in a very efficient way, whereas the PTA approach is slower
but covers the entire space of solutions.Comment: Submitted to ECRTS 2013 (http://ecrts.eit.uni-kl.de/ecrts13
Model-bounded monitoring of hybrid systems
Monitoring of hybrid systems attracts both scientific and practical
attention. However, monitoring algorithms suffer from the methodological
difficulty of only observing sampled discrete-time signals, while real
behaviors are continuous-time signals. To mitigate this problem of sampling
uncertainties, we introduce a model-bounded monitoring scheme, where we use
prior knowledge about the target system to prune interpolation candidates.
Technically, we express such prior knowledge by linear hybrid automata (LHAs) -
the LHAs are called bounding models. We introduce a novel notion of monitored
language of LHAs, and we reduce the monitoring problem to the membership
problem of the monitored language. We present two partial algorithms - one is
via reduction to reachability in LHAs and the other is a direct one using
polyhedra - and show that these methods, and thus the proposed model-bounded
monitoring scheme, are efficient and practically relevant.Comment: This is the author (and slightly extended) version of the manuscript
of the same name published in the proceedings of the 12th ACM/IEEE
International Conference on Cyber-Physical Systems (ICCPS 2021
Dense Integer-Complete Synthesis for Bounded Parametric Timed Automata
Ensuring the correctness of critical real-time systems, involving concurrent
behaviors and timing requirements, is crucial. Timed automata extend
finite-state automata with clocks, compared in guards and invariants with
integer constants. Parametric timed automata (PTAs) extend timed automata with
timing parameters. Parameter synthesis aims at computing dense sets of
valuations for the timing parameters, guaranteeing a good behavior. However, in
most cases, the emptiness problem for reachability (i.e., whether the emptiness
of the parameter valuations set for which some location is reachable) is
undecidable for PTAs and, as a consequence, synthesis procedures do not
terminate in general, even for bounded parameters. In this paper, we introduce
a parametric extrapolation, that allows us to derive an underapproximation in
the form of linear constraints containing not only all the integer points
ensuring reachability, but also all the (non-necessarily integer) convex
combinations of these integer points, for general PTAs with a bounded parameter
domain. We also propose two further algorithms synthesizing parameter
valuations guaranteeing unavoidability, and preservation of the untimed
behavior w.r.t. a reference parameter valuation, respectively. Our algorithms
terminate and can output constraints arbitrarily close to the complete result.
We demonstrate their applicability and efficiency using the tool Rom\'eo on two
classical benchmarks.Comment: This is an extended version of the paper by the same authors
published in the proceedings of the 9th International Workshop on
Reachability Problems (RP 2015
Metal-free catalytic C-H bond activation and borylation of heteroarenes
Transition metal complexes are efficient catalysts for the C-H bond functionalization of heteroarenes to generate useful products for the pharmaceutical and agricultural industries. However, the costly need to remove potentially toxic trace metals from the end products has prompted great interest in developing metal-free catalysts that can mimic metallic systems. We demonstrated that the borane (1-TMP-2-BH2-C6H4)2 (TMP, 2,2,6,6-tetramethylpiperidine) can activate the C-H bonds of heteroarenes and catalyze the borylation of furans, pyrroles, and electron-rich thiophenes. The selectivities complement those observed with most transition metal catalysts reported for this transformation
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