Mathematische Modellierung des Spröd-duktil-Übergangs und eine Anwendung auf ferritische Stähle

This thesis contributes to the mathematical modeling of the ductile-brittle-transition by giving two models based on dislocation dynamics and discussing an analogy to superconductivity. Following introductory chapters on the motivation for this work and the connection between fracture and permanent plastic deformation by dislocations, the models are introduced in the third chapter. Both models describe the influence of moving dislocations on the stress field in the vicinity of a static notch or crack. The first model gives a differential equation for the time evolution of the stress intensity at a crack tip, the sum of the external intensity by applied loads and an internal contribution by stress fields of dislocations. The second model describes an area close to a notch tip, in which dislocations can travel fast enough to follow a fixed stress level moving by external loads. Both models show, that plastic deformation has to reach a certain magnitude to influence fracture behavior significantly. Thereby, they explain the differences of fracture toughness values and their scatter between the low temperature regime of cleavage fracture and the transition regime, and the occurence of cleavage in the presence of considerable plastic flow. While the first model gives an explicit transition criterion, the second model shows the transition to be a property of a structure, rather than of a material. Effects of stress triaxiality, size and shape of a specimen can be accounted for in the second model. We give an explanation of Master Curve behavior and the correlation of yield stress shift and fracture toughness shift under irradiation and show, why yield stress and toughness do not correlate as strongly as funtions of temperature. Both models are critically discussed with respect to the limits of their applicability. The final chapter describes the ductile-brittle-transition as a transition of a superconductor of the first kind (brittle) to the second kind (ductile).Diese Dissertation behandelt die mathematische Modellierung des Spröd-duktil-Übergangs, indem zwei Modelle für den Übergang auf versetzungsdynamischer Grundlage und eine Analogie zur Supraleitung beschrieben werden. Nach einführenden Kapiteln über den Hintergrund der Arbeit und den Zusammenhang von Bruchverhalten und plastischer Deformation durch Versetzungen, werden die Modelle im dritten Kapitel vorgestellt. Beide behandeln den Einfluss bewegender Versetzungen auf das Spannungsfeld nahe einer statischen Kerb- oder Rissspitze. Das erste Modell führt auf eine Differentialgleichung für die Zeitabhängigkeit der Spannungsintensität an einer Rissspitze als Summe der von äußeren Kräften und Versetzungen aufgeprägten Spannungsintensität. Das zweite Modell beschreibt eine Region bei einer Kerbspitze, in der sich Versetzungen schnell genug bewegen, um einem festen Spannungsniveau zu folgen. Beide Modelle zeigen, dass sich Plastizität erst ab einer gewissen Stärke merklich auf das Bruchverhalten auswirkt. Dadurch erklären sie die Unterschiede der Bruchzähigkeit und ihrer Streuung zwischen dem Tieftemperaturbereich mit Spaltbruch und dem Übergangsbereich und das Auftreten von Spaltbruch bei erheblicher plastischer Deformation. Während das erste Modell ein explizites Übergangskriterium gibt, zeigt das zweite, dass der Übergang eine Struktur- und keine Materialeigenschaft ist. Der Einfluss von mehrachsigen Spannungszuständen, Größe und Form der Probe können im zweiten Modell berücksichtigt werden. Wir geben eine Exklärung von Masterkurvenverhalten und Korrelation von Fließspannungs- und Bruchzähigkeitsverschiebung bei Bestrahlung und zeigen, warum Fließspannung und Bruchzähigkeit als Funktionen der Temperatur nicht so stark korrelieren. Beide Modelle werden kritisch bezüglich ihrer Anwendbarkeitsgrenzen diskutiert. Das letzte Kapitel beschreibt den Spröd-duktil-Übergang als Übergang eines Supraleiters erster Art (spröde) zu einem zweiter Art (duktil)

Wilde Urbaniten: Tier-Mensch-Regime im Habitat Großstadt

Die rechtlich-administrative und räumlich-planende Regulation des Vorkommens wildlebender Tiere im urbanen Raum lässt sich drei historisch gewachsenen Regimen zuordnen: Das Regime der Hygiene konstituiert die wilden Tiere der Stadt als Schädlinge, Lästlinge oder Nützlinge, das der Jagd als Nutzwild, Raubwild oder Raubzeug und das des Naturschutzes als Schutzobjekte, als heimisch oder fremd und als Leistungsträger oder Schädlinge. Dieses Regimedenken wandelt sich derzeit in der räumlichen Planungspraxis. Es wird mit Ansätzen eines integrierenden, die Wirkmächtigkeit von Tieren anerkennenden und nutzenden sowie offensiv-gestaltenden Umgangs mit Tieren experimentiert. Die interdisziplinäre Planungsmethode Animal-Aided Design berücksichtigt Tiere im Planungsprozess als Akteure, die urbane Räume aktiv mitgestalten und die Lebensqualität in der Stadt aufwerten

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German

The role of constituents in multiword expressions: An interdisciplinary, cross-lingual perspective

Multiword expressions (MWEs), such as noun compounds (e.g. nickname in English, and Ohrwurm in German), complex verbs (e.g. give up in English, and aufgeben in German) and idioms (e.g. break the ice in English, and das Eis brechen in German), may be interpreted literally but often undergo meaning shifts with respect to their constituents. Theoretical, psycholinguistic as well as computational linguistic research remain puzzled by when and how MWEs receive literal vs. meaning-shifted interpretations, what the contributions of the MWE constituents are to the degree of semantic transparency (i.e., meaning compositionality) of the MWE, and how literal vs. meaning-shifted MWEs are processed and computed. This edited volume presents an interdisciplinary selection of seven papers on recent findings across linguistic, psycholinguistic, corpus-based and computational research fields and perspectives, discussing the interaction of constituent properties and MWE meanings, and how MWE constituents contribute to the processing and representation of MWEs. The collection is based on a workshop at the 2017 annual conference of the German Linguistic Society (DGfS) that took place at Saarland University in Saarbrücken, German