The kinetics of oxidation of Ni (Ni + co)-Nbc superalloys represented by the alloy Ni-Nbc and (Ni + co)-Nbc was studied. The alloys were studied in the cast state. It was found that the alloys oxidize according to a p...
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The kinetics of oxidation of Ni (Ni + co)-Nbc superalloys represented by the alloy Ni-Nbc and (Ni + co)-Nbc was studied. The alloys were studied in the cast state. It was found that the alloys oxidize according to a parabolic law. The analysis of diffusion-oxidation processes at a temperature of 1100 degrees c in air indicates an increase in heat resistance as a result of intensification of scale sintering and the formation on the surface of superalloys of a diffusion barrier layer of chromium, aluminum, and niobium oxides. The research result determines the prospects of creating industrial alloys for power engineering based on Ni (Ni + co)-Nbc superalloys.
One can write dependently typed functional programs in coq, and prove them correct in coq;one can write low-level programs in c, and prove them correct with a c verification tool. We demonstrate how to write programs ...
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One can write dependently typed functional programs in coq, and prove them correct in coq;one can write low-level programs in c, and prove them correct with a c verification tool. We demonstrate how to write programs partly in coq and partly in c, and interface the proofs together. The Verified Foreign Function Interface (VeriFFI) guarantees type safety and correctness of the combined program. It works by translating coq function types (and constructor types) along with coq functional models into VST function-specifications;if the user can prove in VST that the c functions satisfy those specs, then the c functions behave according to the user-specified functional models (even though the c implementation might be very different) and the proofs of coq functions that call the ccode can rely on that behavior. To achieve this translation, we employ a novel, hybrid deep/shallow description of coq dependent types.
Separation logic has become an important tool for formally capturing and reasoning about the ownership patterns of imperative programs, originally for paper proof, and now the foundation for industrial static analyses...
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Separation logic has become an important tool for formally capturing and reasoning about the ownership patterns of imperative programs, originally for paper proof, and now the foundation for industrial static analyses and multiple proof tools. However, there has been very little work on program testing of separation- logic specifications in concrete execution. At first sight, separation-logic formulas are hard to evaluate in reasonable time, with their implicit quantification over heap splittings, and other explicit existentials. In this paper we observe that a restricted fragment of separation logic, adopted in the cN proof tool to enable predictable proof automation, also has a natural and readable computational interpretation, that makes it practically usable in runtime testing. We discuss various design issues and develop this as a c+cN source to c source translation, Fulminate. This adds checks - including ownership checks and ownership transfer - for ccode annotated with cN pre- and post-conditions;we demonstrate this on nontrivial examples, including the allocator from a production hypervisor. We formalise our runtime ownership testing scheme, showing (and proving) how its reified ghost state correctly captures ownership passing, in a semantics for a small c-like language.
We introduce the notion of locally parallel sets of elements of c ⁎ -algebras which generalizes that of norm attainment sets of continuous functions, and consider a preserver problem on order isomorphisms of locally p...
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We introduce the notion of locally parallel sets of elements of c ⁎ -algebras which generalizes that of norm attainment sets of continuous functions, and consider a preserver problem on order isomorphisms of locally parallel sets. It is shown that unitary multiplications of Jordan ⁎-isomorphisms give examples of order isomorphisms of locally parallel sets. This is achieved by analyzing the quasi-strong Birkhoff-James orthogonality, a new orthogonality relation between the original Birkhoff-James orthogonality and the strong Birkhoff-James orthogonality. Moreover, it is shown that every order isomorphism of locally parallel sets on the c ⁎ -algebra of all n × n complex matrices is essentially implemented by two unitary matrices provided that n ≥ 3 .
The microstructural evolution and its effect on the impact toughness of Super304H austenitic stainless steel weld metal during long-term aging at 650 °c was investigated in detail. The fractography and preci...
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The microstructural evolution and its effect on the impact toughness of Super304H austenitic stainless steel weld metal during long-term aging at 650 °c was investigated in detail. The fractography and precipitation evolution in the aged samples were characterized by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and transmission electron microscope (TEM). During the aging process, the impact toughness of the weld metal decreased continuously over time, exhibiting a significantly more pronounced tendency towards long-term aging embrittlement compared to the base metal. The main reason for this was the continuous precipitation of M 23 c 6 along the grain boundaries, which formed a network structure distribution. Furthermore, electron backscatter diffraction (EBSD) analysis revealed that the orientation relationship between the M 23 c 6 precipitates along the grain boundaries and the matrix changed from a semi-coherent relationship in the as-welded metal to a non-coherent relationship in the aged metal, which also had an adverse effect on the impact toughness. The precipitation kinetics curve of M 23 c 6 phase in the weld metal during aging was established for investigating the evolution of impact toughness after long-term exposure. Moreover, a novel model between the impact toughness W of weld metal and the M 23 c 6 phase parameter (grain boundary equivalent width, B ) was proposed to further reveal the mechanism for the intergranular fracture caused by the increase of the grain boundary equivalent width (i.e., carbide coarsening) and provide guidance for predicting changes in weld metal toughness during long-term aging.
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