On the groove pressing of Ni-W alloy: microstructure, texture and mechanical properties evolution

International audienceThe microstructure, texture and mechanical properties of the Ni-14%W(wt.%) alloy with two different initial grain sizes and textures were investigated after groove pressing (GP) at 450 °C to 4 cycles using Electron Back Scatter Diffraction (EBSD) and microhardness measurements. The initial first series was characterized by small equiaxed grains and Cube dominant texture component. The second series has elongated grains and β-fiber texture. EBSD analysis has shown that GP processing led to a slight refinement (less than 15%) of equiaxed grains in series I while greater refinement (~55%) of the mean spacing along normal direction was observed in series II. The texture did not drastically change from the initial ones and was characterized by the weakening of the Cube component in series I and rapid decrease of Copper component for series II. GP processing reduces very slightly the plastic anisotropy of the alloy with initial elongated granular microstructure

Quaternary time scales for the Pontocaspian domain: interbasinal connectivity and faunal evolution

The Pontocaspian (Black Sea - Caspian Sea) region has a very dynamic history of basin development and biotic evolution. The region is the remnant of a once vast Paratethys Sea. It contains some of the best Eurasian geological records of tectonic, climatic and paleoenvironmental change. The Pliocene-Quaternary co-evolution of the Black Sea-Caspian Sea is dominated by major changes in water (lake and sea) levels resulting in a pulsating system of connected and isolated basins. Understanding the history of the region, including the drivers of lake level and faunal evolution, is hampered by indistinct stratigraphic nomenclature and contradicting time constraints for regional sedimentary successions. In this paper we review and update the late Pliocene to Quaternary stratigraphic framework of the Pontocaspian domain, focusing on the Black Sea Basin, Caspian Basin, Marmara Sea and the terrestrial environments surrounding these large, mostly endorheic lake-sea systems

A Tutorial on Concept Learning Part 2: Query Directed Learning

Diffusion restreinte 1 The paradigm of query directed learning, introduced by Angluin [Ang87], has received a great deal of attention in the literature [Ang90, AFP92, AP95, AKST97, GST02, GKS03, KA06]. In the standard concept learning framework, the learner is given a set of examples, the so-called training set, which is used to extrapolate an hypothesis that accurately approximates the target concept. By contrast, in the query directed learning model, the learner has access to an oracle that will answer specific kinds of queries about the target concept. From a cognitive viewpoint, the oracle can be thought as an ideal expert who is capable of helping the learner on identifying the target concept. The purpose of the present note is to provide a general overview of the query-directed learning model. We begin to examine the formal ingredients of the model. Next, we illustrate an application of this model in the setting of monotone DNF formulas. Finally, we conclude this note by discussing about several extensions of the model. 1 The Model The query directed learning model can be viewed as a repeated game between the learne

Knowledge Compilation for Model Counting: Affine Decision Trees

Counting the models of a propositional formula is a key issue for a number of AI problems, but few propositional languages offer the possibility to count models efficiently. In order to fill the gap, we introduce the language EADT of (extended) affine decision trees. An extended affine decision tree simply is a tree with affine decision nodes and some specific decomposable conjunction or disjunction nodes. Unlike standard decision trees, the decision nodes of an EADT formula are not labeled by variables but by affine clauses. We study EADT, and several subsets of it along the lines of the knowledge compilation map. We also describe a CNF-to-EADT compiler and present some experimental results. Those results show that the EADT compilation-based approach is competitive with (and in some cases is able to outperform) the model counter Cachet and the d-DNNF compilationbased approach to model counting

Probable Consistency Checking For Sets Of Propositional Clauses

Inconsistencies inevitably arise in knowledge during practical reasoning

A logic for anytime deduction and anytime compilation

One of the main characteristics of logical reasoning in knowledge based systems is its high computational complexity. Anytime deduction and anytime compilation are two attractive approaches that have been proposed for addressing such a difficulty. The first one offers a compromise between the time complexity needed to compute approximate answers and the quality of these answers. The second one proposes a trade-off between the space complexity of the compiled knowledge base and the number of possible answers that can be efficiently processed by this data structure. The purpose of this paper is to define a logic which handles these two approaches by incorporating several major features. First, the logic is semantically founded on the notion of resource which determines both the accuracy and the cost of approximation. Second, a stepwise procedure is included for improving approximate answers and allowing their convergence to the correct answer. Third, both sound approximations and complete ones are covered. Fourth and nally, the reasoning task may be done off-line and compiled theories can be used for answering many queries. This logic is applied to the specifications of anytime deducers and anytime compilers