Towards a verified compiler prototype for the synchronous language SIGNAL

International audienceSIGNAL belongs to the synchronous languages family which are widely used in the design of safety-critical real-time systems such as avionics, space systems, and nuclear power plants. This paper reports a compiler prototype for SIGNAL. Compared with the existing SIGNAL compiler, we propose a new intermediate representation (named S-CGA, a variant of clocked guarded actions), to integrate more synchronous programs into our compiler prototype in the future. The front-end of the compiler, i.e., the translation from SIGNAL to S-CGA, is presented. As well, the proof of semantics preservation is mechanized in the theorem prover Coq. Moreover, we present the back-end of the compiler, including sequential code generation and multithreaded code generation with time-predictable properties. With the rising importance of multi-core processors in safety-critical embedded systems or cyber-physical systems (CPS), there is a growing need for model-driven generation of multithreaded code and thus mapping on multi-core. We propose a time-predictable multi-core architecture model in architecture analysis and design language (AADL), and map the multi-threaded code to this model

Effect of 165-keV Ar-ion irradiation on microstructural and mechanical properties of zircaloy-4

Cold-worked zircaloy-4 was irradiated by 165 keV Ar ion at room temperature. The aim of the study is to understand the correlation between the dislocation loops induced by irradiation and material hardening. The results revealed ziracloy-4 swelling even at low dose and a strong lattice disorder along and directions. With increasing dose, the microstrain increases while the domain size decreases attributed to the dislocation loops formation. Nanohardness and dislocation density show a similar evolution with the dose, which demonstrate a good correlation between the two parameters. Consequently zircaloy-4 hardening observed at low dose is due to the dislocation loops formation

Structural disorder in sapphire induced by 90.3 MeV xenon ions

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Turbulent Wakes in Turbulent Streams

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Structural disorder in sapphire induced by 90.3 MeV xenon ions

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γ-Ray irradiation effect on GdBO3/silica:Ce3+ composite prepared by sol gel method

Samples of GdBO3 doped with Ce3+ embedded in amorphous silica matrix were obtained by sol gel process and heat-treat at 1000°C for 2h in argon atmosphere. After elaboration, the samples were irradiated with γ-rays using cobalt (60Co) source in the dose range from 1 to 5kGy. The irradiation effect of γ-rays on structural and optical properties of the synthesized samples were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence spectroscopy. XRD and TEM-EDS results reveal that γ-ray irradiation reduces the crystallite size from 55nm to 30nm. It is found from FTIR study that the absorption bands intensity assigned to structural groups containing BO4 and BO3 units as well as the banding of Si-O-Si bond increases with γ-ray dose up to 4kGy. While photoluminescence measurements show that the emission bands attributed to the 5d→4F transition of Ce+3 ion intensity decreases, it is still significant even after irradiation to a dose of 5kGy. From this results it is concluded that the γ-ray irradiation up to a dose of 5kGy improve the structural and morphological quality of the synthesized GdBO3/silica: Ce3+ without altering significantly its luminescence properties

Data consistencies of swift heavy ion induced damage creation in yttrium iron garnet analyzed by different techniques

Pronounced swelling is observed when single crystals of yttrium iron garnet Y3Fe5O12 (YIG) are irradiated in the electronic energy loss regime with various swift heavy ions. The out-of-plane swelling was measured by scanning across the border line between an irradiated and a virgin area of the sample surface with the tip of a profilometer. The step height varied between 20 and 600 nm depending on fluence, electronic energy loss and total range of the ions. The step height divided by the ion range as a function of the ion fluence exhibits a linear increase in the initial phase and saturates at high fluences leading to a density decrease of around 1.7%. With complementary channeling-Rutherford-backscattering experiments (c-RBS), the damage fraction and the corresponding damage cross section were extracted and compared to the cross section deduced from swelling measurements. Irradiation effects were also characterized by scanning force microscopy (SFM). A threshold for damage creation as deduced from all the present physical characterizations is 5.5 ± 1.0 keV/nm. The value is in full agreement with previous measurements confirming that swelling and SFM characterizations can provide information concerning the electronic energy loss threshold for track formation. In contrast, track radii deduced from swelling measurements are smaller and radii from SFM are larger than deduced from c-RBS analysis. The results of Y3Fe5O12 of this work are compared with data obtained for other crystalline oxides and for ionic crystals

Block Library Driven Translation Validation for Dataflow Models in Safety Critical Systems

International audienceModel driven engineering is widely used in the development of complex and safety critical systems. Systems’ designs are specified and validated in domain specific modeling languages and software code is often produced by autocoding. Thus the correctness of the final systems depend on the correctness of those tools. We propose an approach for the formal verification of code generation from dataflow languages, such as Simulink, based on translation validation. It relies on the BlockLibrary DSL for the formal specification and verification of the structure, semantics and variability of the complex block libraries found in these languages. These specifications are then used here for deriving model and block-specific semantic contracts that will be woven into the generated C code. We present two different approaches for performing the block matching and weaving step. Finally, we rely on the Frama-C toolset and state-of-the-art SMT solvers for verifying the annotated code