A model for the austenite-ferrite phase transition in steel including misfit stress

We present a thermodynamically consistent model to describe the austenite-ferrite phase transition in steel. We consider the influence of the mechanical displacement field due to eigenstrains caused by volumetric expansion. The model equations are derived in a systematical framework. They are based on the conservation laws for mass and momentum and the second law of thermodynamics. By means of numerical computations for a simplified interface controlled model, we examine the influence of the mechanical contributions to the transformation kinetics and the equilibrium states

Temporal homogenization of a nonlinear parabolic system

In this paper we develop are two-scale model for a nonlinear parabolic system. Assuming a rapidly oscillating inhomogeneity with period ε for one equation we carry out a formal periodic expansion to obtain a homogenized equation coupled to a local in time cell problem. We justify the expansion by deriving an error estimate between the original and the two-scale model and show numerical simulations, which confirm the analytically derived error estimate

Conflict or consensus: East Germany, the Soviet Union and Deutschlandpolitik 1958-1984.

http://archive.org/details/conflictorconsen00petzN

Topology optimization subject to additive manufacturing constraints

In Topology Optimization the goal is to find the ideal material distribution in a domain subject to external forces. The structure is optimal if it has the highest possible stiffness. A volume constraint ensures filigree structures, which are regulated via a Ginzburg-Landau term. During 3D Printing overhangs lead to instabilities, which have only been tackled unsatisfactorily. The novel idea is to incorporate an Additive Manufacturing Constraint into the phase field method. A rigorous analysis proves the existence of a solution and leads to first order necessary optimality conditions. With an Allen-Cahn interface propagation the optimization problem is solved iteratively. At a low computational cost the Additive Manufacturing Constraint brings about support structures, which can be fine tuned according to engineering demands. Stability during 3D Printing is assured, which solves a common Additive Manufacturing problem

Topology optimization subject to additive manufacturing constraints

In topology optimization the goal is to find the ideal material distribution in a domain subject to external forces. The structure is optimal if it has the highest possible stiffness. A volume constraint ensures filigree structures, which are regulated via a Ginzburg–Landau term. During 3D printing overhangs lead to instabilities. As a remedy an additive manufacturing constraint is added to the cost functional. First order optimality conditions are derived using a formal Lagrangian approach. With an Allen-Cahn interface propagation the optimization problem is solved iteratively. At a low computational cost the additive manufacturing constraint brings about support structures, which can be fine tuned according to demands and increase stability during the printing process

Topology optimization subject to additive manufacturing constraints

In Topology Optimization the goal is to find the ideal material distribution in a domain subject to external forces. The structure is optimal if it has the highest possible stiffness. A volume constraint ensures filigree structures, which are regulated via a Ginzburg-Landau term. During 3D Printing overhangs lead to instabilities, which have only been tackled unsatisfactorily. The novel idea is to incorporate an Additive Manufacturing Constraint into the phase field method. A rigorous analysis proves the existence of a solution and leads to first order necessary optimality conditions. With an Allen-Cahn interface propagation the optimization problem is solved iteratively. At a low computational cost the Additive Manufacturing Constraint brings about support structures, which can be fine tuned according to engineering demands. Stability during 3D Printing is assured, which solves a common Additive Manufacturing problem

Production of tetra-methylpyrazine using engineered Corynebacterium glutamicum.

Corynebacterium glutamicum ATCC 13032 is an established and industrially-relevant microbial host that has been utilized for the expression of many desirable bioproducts. Tetra-methylpyrazine (TMP) is a naturally occurring alkylpyrazine with broad applications spanning fragrances to resins. We identified an engineered strain of C. glutamicum which produces 5 ​g/L TMP and separately, a strain which can co-produce both TMP and the biofuel compound isopentenol. Ionic liquids also stimulate TMP production in engineered strains. Using a fed batch-mode feeding strategy, ionic liquid stimulated strains produced 2.2 ​g/L of tetra-methylpyrazine. We show that feedback from a specific heterologous gene pathway on host physiology leads to acetoin accumulation and the production of TMP

Smart control of electromagnetically driven dosing pumps

Electromagnetically driven dosing pumps are suitable for metering any kind of liquid in motor vehicles in a precise manner. Due to the working principle and the pump design, an undesired noise occurs when the armature reaches the mechanical end stops. The noise can be reduced by an adequate self-learning control of the supply energy using a position estimation and velocity control. Based on preliminary investigations /1/, a method for noise reduction is realised by using a user-friendly, tiny and cost-efficient hardware, which enables a use in series manufacturing. The method requires only a voltage and current measurement as input signals. The core of the hardware is an 8-bit microcontroller with 8 kilobytes flash memory including necessary peripherals. A smart software development enables an implementation of the entire noise reduction method onto the tiny flash memory

Räumliche Manifestationen sozialer Schließung: Methoden, Daten, Mechanismen

Ein Ziel der Stadt-, bzw. Raumsoziologie sollte es sein, über reine Beschreibung hinausgehende erklärende Mechanismen raumbezogener sozialer Öffnungs- und Schließungsprozesse zu identifizieren. Im folgenden Aufsatz weisen wir darauf hin, dass es in der deutschsprachigen Soziologie bereits einmal Ansätze eine theoriegeleiteten, handlungsbasierten Stadtforschung gab. Wir argumentieren, dass die damals aufgestellten Theorien aufgrund mangelnder Daten und statistischer Methoden nicht adäquat empirisch untersucht werden konnten und daher zu Recht teilweise stark kritisiert wurden. Die gesteigerten Möglichkeiten der soziologischen Nutzung raumbezogener Daten und Methoden eröffnen heute jedoch einen neuen, vielversprechenden, Zugang zu alten Fragestellungen. Wir skizzieren erstens die Grundprinzipien der analytischen Perspektive in der Soziologie, wonach räumlich-physische Konstellationen als das regelmäßige Resultat individueller Handlungen aufgefasst werden können und selbst wiederum neue Handlungsbedingungen darstellen. Zweitens geben wir einen kurzen Überblick über innovative Daten, sowie Erhebungs- und Analysemethoden, die zur Untersuchung raumbezogener sozialer Mechanismen geeignet scheinen. Daraus leiten wir, drittens, schließlich einige Desiderate für die zukünftige Forschung ab