Morphological Productivity in the Lexicon

In this paper we outline a lexical organization for Turkish that makes use of lexical rules for inflections, derivations, and lexical category changes to control the proliferation of lexical entries. Lexical rules handle changes in grammatical roles, enforce type constraints, and control the mapping of subcategorization frames in valency-changing operations. A lexical inheritance hierarchy facilitates the enforcement of type constraints. Semantic compositions in inflections and derivations are constrained by the properties of the terms and predicates. The design has been tested as part of a HPSG grammar for Turkish. In terms of performance, run-time execution of the rules seems to be a far better alternative than pre-compilation. The latter causes exponential growth in the lexicon due to intensive use of inflections and derivations in Turkish.Comment: 10 pages LaTeX, {lingmacros,avm,psfig}.sty, 1 figure, 1 bibtex fil

A unified creep-plasticity model suitable for thermo-mechanical loading

An experimentally based unified creep-plasticity constitutive model was implemented for 1070 steel. Accurate rate and temperature effects were obtained for isothermal and thermo-mechanical loading by incorporating deformation mechanisms into the constitutive equations in a simple way

A Sign-Based Phrase Structure Grammar for Turkish

This study analyses Turkish syntax from an informational point of view. Sign based linguistic representation and principles of HPSG (Head-driven Phrase Structure Grammar) theory are adapted to Turkish. The basic informational elements are nested and inherently sorted feature structures called signs. In the implementation, logic programming tool ALE (Attribute Logic Engine) which is primarily designed for implementing HPSG grammars is used. A type and structure hierarchy of Turkish language is designed. Syntactic phenomena such a s subcategorization, relative clauses, constituent order variation, adjuncts, nomina l predicates and complement-modifier relations in Turkish are analyzed. A parser is designed and implemented in ALE.Comment: MS. Thesis, Dept. of Computer Engineering, Middle East Technical University, Ankara January, 1996, 97 pages. 5 eps figures, uses avm,psfig,lingmacros,tree-dvips,ulem,QobiTree,alltt ulem.sty,QobiTree.sty,alltt.sty and eps files included in ta

Twin nucleation in Fe-based bcc alloys - Modeling and experiments

We develop an analytical expression for twin nucleation stress in bcc metal and alloys considering generalized planar fault energy and the dislocations bounding the twin nucleus. We minimize the total energy to predict the twinning stress relying only on parameters that are obtained through atomistic calculations, thus excluding the need for any empirical constants. We validate the present approach by means of precise measurements of the onset of twinning in bcc Fe-50at% Cr single crystals showing excellent agreement. The experimental observations of the three activated slip systems of symmetric configuration in relation to the twinning mechanism are demonstrated via transmission electron microscopy techniques along with digital image correlation. We then confirm the validity of the model for Fe, Fe-25at% Ni and Fe-3at% V alloys compared with experiments from the literature to show general applicability

Twin migration in Fe-based bcc crystals: Theory and experiments

We establish an overall energy expression to determine the twin migration stress in bcc metals. Twin migration succeeds twin nucleation often after a load drop, and a model to establish twin migration stress is of paramount importance. We compute the planar fault energy barriers and determine the elastic energies of twinning dislocations including the role of residual dislocations (br) and twin intersection types such as 1 1 0, 1 1 3 and 2 1 0. The energy expression derived provides the twin migration stress in relation to the twin nucleation stress with a ratio of 0.5-0.8 depending on the resultant residual burgers vector and the intersection types. Utilizing digital image correlation, it was possible to differentiate the twin nucleation and twin advancement events experimentally, and transmission electron microscopy observations provided further support to the modelling efforts. Overall, the methodology developed provides an enhanced understanding of twin progression in bcc metals, and most importantly the proposed model does not rely on empirical constants. We utilize Fe-50at.%Cr in our experiments, and subsequently predict the twin migration stress for pure Fe, and Fe-3at.%V from the literature showing excellent agreement with experiments. © 2014 Taylor & Francis

Superelasticity in high strength heterophase single crystals of Ni51.0Ti36.5Hf12.5 alloy

The effect of precipitated disperse H-phase particles on the thermoelastic B2–B19′ martensitic transformation (MT) under compressive load has been studied on [001]-, [236]-, and [223]-oriented single crystals of Ni51.0Ti36.5Hf12.5 (at %) alloy in the initial (as-grown) state. It is established that, in Ni51.0Ti36.5Hf12.5 single crystals containing disperse H-phase particles with dimensions within 125–150 nm at a volume fraction of ~30%, neither the critical stresses of martensite formation nor superelasticity strain depend on the orientation. Fully reversible B2–B19′ MTs in Ni51.0Ti36.5Hf12.5 single crystals have been observed in tests at external axial stresses up to 1700 MPa and temperatures up to Tt ~ 373 K

Modeling of Cyclic Ratchetting Plasticity, Part II: Comparison of Model Simulations With Experiments,"

The material constants of the new plasticity model proposed in the first part of the paper can be divided into two independent groups. The first group, c (,> and. r (l&gt

Multi-scale crack closure measurements with digital image correlation on Haynes 230

An experimental campaign was developed to study fatigue crack growth in Haynes 230, a Ni-based superalloy. The effects of crack closure were investigated with digital image correlation, by applying two different approaches. Initially, full field regression algorithms were applied to extract the effective stress intensity factor ranges from the singular displacement field measured at crack tips. Local closure measurements were then performed by considering crack flanks relative displacements. Two points virtual extensometers were applied in this phase. Experimental results were then compared to the reference da/dN –∆Keff curve: it was found that the correct estimation of crack opening levels shifts all the experimental points on the reference curve, showing that DIC can be successfully applied to measure crack closure effects

Techniques for the analysis of total energy and labor of industrial plants / CAC No. 198

Bibliography: p. 24