Numerical simulation of inductive heating processes

For product optimization regarding weight reduction, material properties have to be adapted efficiently. To achieve this, new compositions of materials can be created or the manufacturing process can be changed in a way that heterogeneous distributions of material properties are enabled. An example for such an improved process chain is the production of thermo-mechanically graded structures like shafts. The manufacturing method mainly consists of three stages. The first one is characterized by a local temperature increase of the workpiece due to inductive heating. In the second phase the workpiece is deformed and simultaneously cooled throughout the contact with the forming die. In the last step, however, a high pressured air stream is applied, leading to a partial cooling of the workpiece. The inductive heating step is controlled by an alternating current inducing a high frequency magnetic field, which causes a temperature increase due to the resulting eddy currents. To analyse this process, the coupling between the electric and the magnetic field is described by the fully coupled Maxwell equations. Moreover the heat conduction equation is considered to describe thermal effects. To solve this multifield the equations are in the first step decoupled using an additional time differentiation. In the second step an axisymmetric case is considered, motivated by the fact that the inductive heating process of a cylindrical shaft is analysed. Afterwards the resulting equations are spatially discretized by the Galerkin finite element method. The temporal discretization is carried out via the Newmark method so that afterwards the electrical source distribution can be achieved. As a consequence the temperature evolution is determined in a postprocessing step

Activation of gene expression during hypersensitive response (HR) induced by auxin in the grapevine rootstock cultivar 'Börner'

The cultivar ‘Börner’ is one of the very few grape phylloxera (Daktulosphaira vitifoliae Fitch) resistant rootstocks commercially available. In contrast to tolerant or sensitive rootstocks, ‘Börner’ roots react to grape phylloxera attack with a hypersensitive response leading to necroses around the puncture sites. In this study, we identified genes differentially up-regulated during the HR. HR was chemically induced in root cells by the application of indol-acetic-acid (IAA). After a cDNA subtraction of induced and non-induced material, the subtracted cDNA-samples were also hybridized to Arabidopsis microarray chips to identify differentially expressed candidate genes. The microarray data were analyzed and differentially expressed genes were grouped into different functional categories, e.g. signal transduction pathways, transcription factors, defence associated genes. Primers were designed to target genes of interest putatively involved in the HR. So far, 38 ESTs induced in ‘Börner’ roots undergoing a HR have been sequenced and annotated.

Quark mass thresholds in QCD thermodynamics

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.Comment: 14 pages. v2: minor additions and clarifications; published versio

123I-Methyljodbenzylguanidin- (MIBG-) Szintigraphie: Paradoxe Nuklidspeicherung eines onkozytären Nebennierenrindenkarzinoms

Zusammenfassung: Das mit Radiojod markierte Katecholaminanalogon Methyljodbenzylguanidin (MIBG) eignet sich aufgrund seiner selektiven Aufnahme in chromaffine Gewebe in hervorragender Weise für die bildgebende Diagnostik des Phäochromozytoms und besitzt hier nach Literaturangaben eine Sensitivität von etwa 90% und eine Spezifität von annähernd 100%. Die falsch-positive oder paradoxe MIBG-Speicherung einer adrenokortikalen Neoplasie stellt demgegenüber eine Rarität dar. Wir berichten über diese Situation am Beispiel eines metastasierten onkozytären Nebennierenrindenkarzinoms mit teilweise therapeutisch genutzter MIBG-Speicherung in verschiedenen Tumormanifestatione

A mechanism for the non-Fermi-liquid behavior in CeCu_{6-x}Au_x

We propose an explanation for the recently observed non-Fermi-liquid behavior of metallic alloys CeCu_{6-x}Au_x: near x=0.1, the specific heat c is proportional to T \ln (T_0/T) and the resistivity increases linearly with temperature T over a wide range of T. These features follow from a model in which three-dimensional conduction electrons are coupled to two-dimensional critical ferromagnetic fluctuations near the quantum critical point, x_{c}=0.1. This picture is motivated by the neutron scattering data in the ordered phase (x=0.2) and is consistent with the observed phase diagram.Comment: 4 pages, LaTeX, 3 figure

Storage of correlated patterns in a perceptron

We calculate the storage capacity of a perceptron for correlated gaussian patterns. We find that the storage capacity $\alpha_c$ can be less than 2 if similar patterns are mapped onto different outputs and vice versa. As long as the patterns are in general position we obtain, in contrast to previous works, that $\alpha_c \geq 1$ in agreement with Cover's theorem. Numerical simulations confirm the results.Comment: 9 pages LaTeX ioplppt style, figures included using eps

The infrared behaviour of the static potential in perturbative QCD

The definition of the quark-antiquark static potential is given within an effective field theory framework. The leading infrared divergences of the static singlet potential in perturbation theory are explicitly calculated.Comment: 4 pages, 2 postscript figures, uses revtex.st

van der Waals density functionals built upon the electron-gas tradition: Facing the challenge of competing interactions

The theoretical description of sparse matter attracts much interest, in particular for those ground-state properties that can be described by density functional theory (DFT). One proposed approach, the van der Waals density functional (vdW-DF) method, rests on strong physical foundations and offers simple yet accurate and robust functionals. A very recent functional within this method called vdW-DF-cx [K. Berland and P. Hyldgaard, Phys. Rev. B 89, 035412] stands out in its attempt to use an exchange energy derived from the same plasmon-based theory from which the nonlocal correlation energy was derived. Encouraged by its good performance for solids, layered materials, and aromatic molecules, we apply it to several systems that are characterized by competing interactions. These include the ferroelectric response in PbTiO$_3$, the adsorption of small molecules within metal-organic frameworks (MOFs), the graphite/diamond phase transition, and the adsorption of an aromatic-molecule on the Ag(111) surface. Our results indicate that vdW-DF-cx is overall well suited to tackle these challenging systems. In addition to being a competitive density functional for sparse matter, the vdW-DF-cx construction presents a more robust general purpose functional that could be applied to a range of materials problems with a variety of competing interactions

On the Microscopic Origin of Cholesteric Pitch

We present a microscopic analysis of the instability of the nematic phase to chirality when molecular chirality is introduced perturbatively. We show that previously neglected short-range biaxial correlations play a crucial role in determining the cholesteric pitch. We propose an order parameter which quantifies the chirality of a molecule.Comment: RevTeX 3.0, 4 pages, one included eps figure. Published versio