New investigation of phase equilibria in the system Al-Cu-Si

The phase equilibria and invariant reactions in the system Al-Cu-Si were investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe micro analysis (EPMA). Isothermal phase equilibria were investigated within two isothermal sections. The isothermal section at 500?°C covers the whole ternary composition range and largely confirms the findings of previous phase diagram investigations. The isothermal section at 700?°C describes phase equilibria only in the complex Cu-rich part of the phase diagram. A new ternary compound τ was found in the region between (Al,Cu)-γ(1) and (Cu,Si)-γ and its solubility range was determined. The solubility of Al in κ-CuSi was found to be extremely high at 700?°C. In contrast, no ternary solubility in the β-phase of Cu-Al was found, although this phase is supposed to form a complete solid solution according to previous phase diagram assessments. Two isopleths, at 10 and 40?at.% Si, were investigated by means of DTA and a partial ternary reaction scheme (Scheil diagram) was constructed, based on the current work and the latest findings in the binary systems Al-Cu and Cu-Si. The current study shows that the high temperature equilibria in the Cu-rich corner are still poorly understood and additional studies in this area would be favorable.     

Power law model for subjective mental workload and validation through air traffic control human-in-the-loop simulation

Cognition, Technology & Work - We provide evidence for a power law relationship between the subjective one-dimensional Instantaneous Self Assessment workload measure (five-level ISA-WL scale)...     

The efficiency of various thermoluminescence dosemeter types to heavy ions

Dose verification in heavy-ion beams using passive dosemeter systems, e.g. thermoluminescence dosemeters (TLDs), is crucial due to the changing efficiency of the dosemeters for different ion species and linear energy transfer (LET) values. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. TLDs can only be established as a 'reference' system in heavy-ion beams or other radiation fields if the efficiency functions for all contributing ion species and LET values are provided. In the framework of a research project of the Atominstitute of the Austrian Universities irradiations with various ions were performed in the years 2001-2003 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute for Radiological Sciences (NIRS) in Chiba, Japan. Efficiency values were recorded in dependence on ion species and LET in a range from 2 to 400 keV microm(-1). The efficiencies of five different commercially available TLD materials namely TLD 600, TLD 700, TLD 700H, TLD 300 and TLD 200 were investigated.     

Quasi-absolute measurement of aspheres with a combined diffractive optical element as reference

We have already reported a method for the quasi-absolute test of rotationally symmetric aspheres by means of combined diffractive optical elements (combo-DOEs). The combo-DOEs carry the information for the ideal shape of an aspheric surface under test as well as a spherical wave for the measurement at the cat's eye position. An experimental demonstration of the procedure is given. Measurements with two different designs of combo-DOEs have been conducted, and their relative advantages and disadvantages are discussed.     

New optimization algorithm for the synthesis of rugate optical coatings

A model of a rugate coating that takes into account production potentialities of the Leybold Syrus Pro 1100 deposition system is presented. An efficient algorithm for the synthesis of rugate coatings is proposed. Numerical results are also presented.     

Absolute calibration in grazing incidence interferometry via rotational averaging

Interferometry in grazing incidence can be used to test cylindrical mantle surfaces. The absolute accuracy of the resulting surface profiles is limited by systematic wavefront aberrations caused in the interferometer, in particular due to an inversion of the test wavefront in an interferometer using diffractive beam splitters. For cylindrical specimens, a calibration method using four positions has therefore been investigated. This test is combined with another method of optical metrology: the rotational averaging procedure. The implementation for grazing incidence is described and measurement results for hollow cylinders are presented. The gain in accuracy is demonstrated.     

Ermittlung des Wasserdampfdiffusionswiderstandes von Baustoffen in Abhängigkeit von der Baustofftemperatur

Determination of the water vapour diffusion permeability of building materials in dependency on the temperature. Investigations concerning the correlation between the water vapour diffusion permeability (μ ‐value) and the temperature were done at two wood based panels (MDF and OSB), an external thermal insulation compound system, a plaster system and an EPS‐insulation. The investigations were made by analogy to the measurement method described in ISO 12572 but at the chosen temperature levels from –10, –5, 0, 10 up to 50 °C. Based on the measured results, it can be concluded, that the μ ‐value is influenced by the temperature.     

Ermüdungsverhalten geschweißter Rohrknoten von Fachwerkverbundbrücken

Im Verbundbrückenbau werden in letzter Zeit anstatt vollwandiger Ausführungsvarianten vermehrt aufgelöste Fachwerkkonstruktionen aus Stahlhohlprofilen eingesetzt, da diese sowohl in Bezug auf gestalterische Grundsätze als auch hinsichtlich konstruktiver Gesichtspunkte Vorteile versprechen. Hierbei wird insbesondere bei Brückenentwürfen, deren Ausgestaltung eine Vielzahl unterschiedlicher Knotengeometrien erfordert, aus wirtschaftlichen Gründen die Verbindung zwischen Füllstab und Gurtrohr bevorzugt mit direkt geschweißten Knoten anstatt mit Stahlgussknoten ausgeführt. Aufgrund der durch die Knotengeometrie bedingten Spannungskonzentration im Bereich der Schweißnahtkerbe wird der Brückenentwurf bei dieser Ausführungsvariante maßgeblich von der dort vorherrschenden Ermüdungsfestigkeit beeinflusst. Nachdem die in den einschlägigen Normen bereitgestellten Nachweisverfahren gegen Ermüdung für die üblichen im Brückenbau verwendeten Abmessungen nicht anwendbar sind, ist die versuchstechnische Untersuchung zur Absicherung eines ausreichenden Ermüdungswiderstandes bisher unabdingbar. Dieser Beitrag bezieht sich auf insgesamt sieben Versuchskörper, die im Rahmen des Neubaus der Autobahnüberführung Suhl–Lichtenfels auf Ermüdung geprüft wurden. Fatigue behaviour of welded pipe intersections in steel‐concrete composite bridges. In the construction of modern steel‐concrete composite bridges, the steel part is increasingly built by circular hollow sections instead of steel plates. This type of bridge design shows advantageous characteristics concerning architectural aspects as well as benefits in the static load transfer. Especially if the design of the truss girder requires a large number of different node geometries, the connection between the braces and the lower and upper chord are for economic reasons preferably build by directly welded nodes instead of cast steel nodes. Due to the local joint discontinuity of the pipe intersections, the stress distribution is enhanced exactly in the area of the welding seams. As a consequence, the limited fatigue behaviour of the pipe intersections represents the critical aspect in the design of tubular truss‐girder bridges. The difficulties in the design of this construction type are due to the fact that the criterions for fatigue verification given in the current codes do not cover the typical dimensions used in bridge design. Therefore until now it is unavoidable to conduct large‐scale tests in order to verify a sufficient fatigue resistance. This article refers to a total of seven specimens tested on fatigue during the construction of the new Highway Overpass Suhl– Lichtenfels.