355 research outputs found
Deadlock detection of Java Bytecode
This paper presents a technique for deadlock detection of Java programs. The
technique uses typing rules for extracting infinite-state abstract models of
the dependencies among the components of the Java intermediate language -- the
Java bytecode. Models are subsequently analysed by means of an extension of a
solver that we have defined for detecting deadlocks in process calculi. Our
technique is complemented by a prototype verifier that also covers most of the
Java features.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Designing Secure Ethereum Smart Contracts: A Finite State Machine Based Approach
The adoption of blockchain-based distributed computation platforms is growing
fast. Some of these platforms, such as Ethereum, provide support for
implementing smart contracts, which are envisioned to have novel applications
in a broad range of areas, including finance and Internet-of-Things. However, a
significant number of smart contracts deployed in practice suffer from security
vulnerabilities, which enable malicious users to steal assets from a contract
or to cause damage. Vulnerabilities present a serious issue since contracts may
handle financial assets of considerable value, and contract bugs are
non-fixable by design. To help developers create more secure smart contracts,
we introduce FSolidM, a framework rooted in rigorous semantics for designing
con- tracts as Finite State Machines (FSM). We present a tool for creating FSM
on an easy-to-use graphical interface and for automatically generating Ethereum
contracts. Further, we introduce a set of design patterns, which we implement
as plugins that developers can easily add to their contracts to enhance
security and functionality
New-Physics Effects on Triple-Product Correlations in Lambda_b Decays
We adopt an effective-lagrangian approach to compute the new-physics
contributions to T-violating triple-product correlations in charmless Lambda_b
decays. We use factorization and work to leading order in the heavy-quark
expansion. We find that the standard-model (SM) predictions for such
correlations can be significantly modified. For example, triple products which
are expected to vanish in the SM can be enormous (~50%) in the presence of new
physics. By measuring triple products in a variety of Lambda_b decays, one can
diagnose which new-physics operators are or are not present. Our general
results can be applied to any specific model of new physics by simply
calculating which operators appear in that model.Comment: 20 pages, LaTeX, no figures. Added a paragraph (+ references)
discussing nonfactorizable effects. Conclusions unchange
Nucleation and Growth of the Zn-Fe Alloy from a Chloride Electrolyte
In this study, the kinetics of Zn-Fe codeposition was investigated in chloride acidic solution using
cyclic voltammetry. Anomalous codeposition is detected and this mechanism depends on the Zn(II) / Fe(II)
concentration ratio in the electrolytic bath. The study of early stages of electrodeposition showed that Zn-
Fe follows a theoretical response to instantaneous nucleation evolves into a progressive nucleation
according to the model of Scharifker and Hills. The morphology and structure of the coatings is discussed
using characterization techniques. Dense, uniform, and singlephased Zn-Fe coatings could be obtained
with a Zn-Fe ratio of 1/3.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3531
A theory of normed simulations
In existing simulation proof techniques, a single step in a lower-level
specification may be simulated by an extended execution fragment in a
higher-level one. As a result, it is cumbersome to mechanize these techniques
using general purpose theorem provers. Moreover, it is undecidable whether a
given relation is a simulation, even if tautology checking is decidable for the
underlying specification logic. This paper introduces various types of normed
simulations. In a normed simulation, each step in a lower-level specification
can be simulated by at most one step in the higher-level one, for any related
pair of states. In earlier work we demonstrated that normed simulations are
quite useful as a vehicle for the formalization of refinement proofs via
theorem provers. Here we show that normed simulations also have pleasant
theoretical properties: (1) under some reasonable assumptions, it is decidable
whether a given relation is a normed forward simulation, provided tautology
checking is decidable for the underlying logic; (2) at the semantic level,
normed forward and backward simulations together form a complete proof method
for establishing behavior inclusion, provided that the higher-level
specification has finite invisible nondeterminism.Comment: 31 pages, 10figure
An Abstract Framework for Deadlock Prevention in BIP
Part 6: Session 5: Model CheckingInternational audienceWe present a sound but incomplete criterion for checking deadlock freedom of finite state systems expressed in BIP: a component-based framework for the construction of complex distributed systems. Since deciding deadlock-freedom for finite-state concurrent systems is PSPACE-complete, our criterion gives up completeness in return for tractability of evaluation. Our criterion can be evaluated by model-checking subsystems of the overall large system. The size of these subsystems depends only on the local topology of direct interaction between components, and not on the number of components in the overall system. We present two experiments, in which our method compares favorably with existing approaches. For example, in verifying deadlock freedom of dining philosphers, our method shows linear increase in computation time with the number of philosophers, whereas other methods (even those that use abstraction) show super-linear increase, due to state-explosion
Structure and Microstructure Properties of Ball Milled Fe-Zn
Nanocrystalline Fe10 %Zn and Fe30 %Zn alloys have been prepared from pure elemental powders by
mechanical alloying processing in a high energy planetary ball-mill. Microstructural, structural, and magnetic
characterizations of the powders were investigated by X-ray diffraction, and vibrating sample magnometer.
The crystallite size reduction to the nanometer scale is accompanied by an increase in the atomic
level strain. The reaction between Fe and Zn leads to the formation of a bcc Fe(Zn) solid solution with a
lattice parameter close to (0.2912 nm for Fe30 %Zn and 0,2885 nm for Fe10 %Zn) after 5 h of milling. The
complete dissolution of the elemental Zn powders in the a-Fe lattice gives rise to the formation of a highly
disordered Fe(Zn) solid solution, where a-Fe(Zn) nanograins have a crystallite size of (229,29 Å for
Fe10 %Zn (24 h) 30,09 Å for Fe30 %Zn (24 h), on prolonged milling time. The coercivity and magnetization
values are 18,90 (Fe10 %Zn)Oe and 26,59 (Fe30 %Zn) emu/g, respectively, after 24 h of milling.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3514
Rigorous System Design: The BIP Approach
Rigorous system design requires the use of a single powerful component framework allowing the representation of the designed system at different levels of detail, from application software to its implementation. This is essential for ensuring the overall coherency and correctness. The paper introduces a rigorous design flow based on the BIP (Behavior, Interaction, Priority) component framework. This design flow relies on several, tool-supported, source-to-source transformations allowing to progressively and correctly transform high level application software towards efficient implementations for specific platforms
Optical performance of the JWST MIRI flight model: characterization of the point spread function at high-resolution
The Mid Infra Red Instrument (MIRI) is one of the four instruments onboard
the James Webb Space Telescope (JWST), providing imaging, coronagraphy and
spectroscopy over the 5-28 microns band. To verify the optical performance of
the instrument, extensive tests were performed at CEA on the flight model (FM)
of the Mid-InfraRed IMager (MIRIM) at cryogenic temperatures and in the
infrared. This paper reports on the point spread function (PSF) measurements at
5.6 microns, the shortest operating wavelength for imaging. At 5.6 microns the
PSF is not Nyquist-sampled, so we use am original technique that combines a
microscanning measurement strategy with a deconvolution algorithm to obtain an
over-resolved MIRIM PSF. The microscanning consists in a sub-pixel scan of a
point source on the focal plane. A data inversion method is used to reconstruct
PSF images that are over-resolved by a factor of 7 compared to the native
resolution of MIRI. We show that the FWHM of the high-resolution PSFs were
5-10% wider than that obtained with Zemax simulations. The main cause was
identified as an out-of-specification tilt of the M4 mirror. After correction,
two additional test campaigns were carried out, and we show that the shape of
the PSF is conform to expectations. The FWHM of the PSFs are 0.18-0.20 arcsec,
in agreement with simulations. 56.1-59.2% of the total encircled energy
(normalized to a 5 arcsec radius) is contained within the first dark Airy ring,
over the whole field of view. At longer wavelengths (7.7-25.5 microns), this
percentage is 57-68%. MIRIM is thus compliant with the optical quality
requirements. This characterization of the MIRIM PSF, as well as the
deconvolution method presented here, are of particular importance, not only for
the verification of the optical quality and the MIRI calibration, but also for
scientific applications.Comment: 13 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes
and Instrumentation 2010: Optical, Infrared, and Millimeter Wav
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