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Stubborn Sets, Frozen Actions, and Fair Testing

Valmari Antti, Vogler Walter

Fundamenta Informaticae

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2021

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Vol. 178, nr 1/2

139--172

EN

Many partial order methods use some special condition for ensuring that the analysis is not terminated prematurely. In the case of stubborn set methods for safety properties, implementation of the condition is usually based on recognizing the terminal strong components of the reduced state space and, if necessary, expanding the stubborn sets used in their roots. In an earlier study it was pointed out that if the system may execute a cycle consisting of only invisible actions and that cycle is concurrent with the rest of the system in a non-obvious way, then the method may be fooled to construct all states of the full parallel composition. This problem is solved in this study by a method that “freezes” the actions in the cycle. The new method also preserves fair testing equivalence, making it usable for the verification of many progress properties.

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Influence of the welding joint type on safety properties of the armor steel ARMOX 500t

Lazić Vukić, Arsić Dušan, Nikolić Ružica, Uhričik Milan, Hadzima Branislav

System Safety : Human - Technical Facility - Environment

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2019

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Vol. 1, nr 1

753--759

EN

Steels of the ARMOX class belong into a group of the fine-grained, increased strength steels, which are manufactured by the quenching and low tempering procedure, with intensive thermo-mechanical treatment at high temperatures. Combination of the heat and mechanical treatments provides for the fine grains and exceptionally good properties of these steels, while the low-tempering enables relatively high hardness and good ballistic properties. This is why the welding of these steels can negatively affect the material properties in individual zones of the welded joint, what could lead to worsening of the material's ballistic properties, as well. The model plates were welded with the specially prescribed technology; the joints were the but-joint, corner joint and the joint with the shielding plate. In this paper are presented results obtained from the ballistic tests of the plates welded by the prescribed technology; tests consisted of shooting with three types of live ammunition at different types of the welded joints.

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Synthesis and Safety Properties of New Explosive Coordination Compounds

Wojewódka A., Bełzowski J.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 2

351--360

EN

The present paper details the synthesis of new explosive complexes of the DDT type and the investigation of their sensitiveness to friction and impact. Fourteen new compounds, specifically nitrate and perchlorate complexes of various transition block metals with 5-(2,4,6-trinitrophenylamino)tetrazole, commonly called picrylaminotetrazole (PAT), were synthesised. The nitrate complexes were obtained in yields varying between 8.1% and 75.1%, whereas the perchlorate complexes had yields between 24.9% and 67.3%, with yields typically near the upper bound of the given ranges for both classes of complexes and the low yields obtained for [Co(PAT)3](NO3)3 and [Cd(PAT)3](ClO4)3 being the exception rather than the rule. The structures of these compounds were unambiguously established via XRF and IR spectroscopy, as well as via elemental analysis. Detailed analyses of the safety properties of these new materials were performed in terms of their sensitiveness to friction and impact. In general, the obtained compounds present relatively low sensitivity to mechanical stimuli, like friction and impact, with the nitrate complexes of Ni and Zn exhibiting high sensitivity to impact (1-2 Nm). The rest of the investigated compounds show low sensitivity to mechanical stimuli, comparable to classical blasting materials like PETN, RDX or HMX. It should be noted that, in general, the nitrates were more sensitive to mechanical stimuli than their perchlorate analogues.