Funktionale Sicherheit nach ISO 26262 in der Konzeptphase der Entwicklung von Elektrik/Elektronik Architekturen von Fahrzeugen

Die Entwicklung von softwarebasierten Fahrzeugsystemen unter Befolgung des neuen Standards IO 26262 erfordert ein gemeinsames Verständnis sowie die Verzahnung des Vorgehens in beiden Domänen. Ziel dieser Arbeit ist die Berücksichtigung von Anforderungen der funktionalen Sicherheit während der Modellierung von Elektrik/Elektronik Architekturen, ihre formale Zuteilung zu Modellinhalten sowie die Unterstützung nebenläufiger und nachfolgender Aktivitäten der Fahrzeugentwicklung

Qualifizierung einer Messtechnik zur Erfassung freier Grenzflächen bei Flüssigmetallen

The attempt to detect liquid metal surfaces is confronted with a number of difficulties. The main problems are the high reflectivity in vacuum at simultaneously high flow velocities and rapid surface motions. Currently no measurement methods for this problem providing unique results exist. In Order to develop such a method, a projection method has been modified by adding a second (transparent) screen. The development is completed by measurement of the circular hydraulic jump phenomena (GaInSn)

Qualifizierung einer Messtechnik zur Erfassung freier Grenzflächen bei Flüssigmetallen

Die Erfassung freier Grenzflächen bei Flüssigmetallen, wie sie in zukünftigen Anlagen der Kern- und Fusionstechnik eingesetzt werden sollen, ist einer Reihe von Schwierigkeiten unterworfen. Hauptprobleme bereiten die hohe Reflektivität der Oberfläche und die große Geschwindigkeit der Oberflächenbewegung. Die Beobachtung bestehender Flüssigmetalloberflächen, wie der Flüssigmetalltargets MYRRHA und GSI im KALLA-Labor des Forschungszentrums in Karlsruhe, sowie die Untersuchungen für HILIFE-II von Konkachbaev 2000 und IFMIF von Itoh 1998, legen eine zu fordernde Genauigkeit von ±0.3mm bei 100Hz nah. Für diese Anwendungstypen bestehen keine bekannten Messverfahren. Die Entwicklung des DLP-Verfahrens basiert auf der Ergänzung eines Projektionsverfahrens um einen zweiten (transparenten) Schirm, wobei die abgebildeten Laserquerschnitte von einer Hochgeschwindigkeitskamera als mit der Intensität und Farbe codierte Oberflächeninformation erfasst werden. Dies erlaubt die Erreichung der geforderten Genauigkeiten und konnte durch einen entsprechenden sequentiellen aufgebauten Validierungsprozess nachgewiesen werden. Die Qualifizierung wird durch eine raum- und zeitaufgelöste Erfassung des rotationssymmetrischen hydraulischen Sprungs mit eutektischen Gallium Indium Zinn abgeschlossen

Critical Tasks Facing Western Europe and the United States in a Period of Change and Transition. Address by Martin J. Hillenbrand, Assistant Secretary for European Affairs. Department of State Bulletin, 7 June, 1971

No abstract

AB Doradus C: Age, Spectral Type, Orbit, and Comparison to Evolutionary Models

We expand upon the results of Close et al. 2005 regarding the young, low-mass object AB Dor C and its role as a calibration point for theoretical tracks. We present an improved spectral reduction and a new orbital solution with two additional epochs. Our improved analysis confirms our spectral type of M8 (+/- 1) and mass of 0.090+/-0.003 solar masses for AB Dor C. Comparing the results for AB Dor C with other young, low-mass objects with dynamical masses we find a general trend where current evolutionary models tend to over-predict the temperature (or under-predict the mass) for low mass stars and brown dwarfs. Given our precision, there is a ~99% chance that the mass of AB Dor C is underestimated by the DUSTY tracks in the HR diagram.Comment: 7 pages, 10 figures, proceedings for the workshop "Ultralow-mass star formation and evolution", to be published in Astronomische Nachrichten - Astronomical Note

Proper motion of very low mass stars and brown dwarfs in the Pleiades cluster

We report proper motion measurements for 25 very-low mass (VLM) star and brown dwarf (BD) candidates of the Pleiades cluster previously identified by Bouvier et al. (1998). Proper motions are measured with an accuracy of 9 mas/yr, compared to an expected tangential motion of about 50 mas/yr for Pleiades members. Of the 25 candidates, 15 have a membership probability of 95% or more and 7 are rejected as being field dwarfs. The 3 remaining candidates exhibit independent evidence for membership (lithium absorption or long-term proper motion). From the firm identification of Pleiades VLM and BD members, the cluster's substellar mass function is revised to dN/dM \propto M^{-0.5} in the mass range from 0.04 to 0.3 M_solar.Comment: 7 pages, 2 tables, 2 figures, accepted by A&

Modeling the Formation of Giant Planet Cores I: Evaluating Key Processes

One of the most challenging problems we face in our understanding of planet formation is how Jupiter and Saturn could have formed before the the solar nebula dispersed. The most popular model of giant planet formation is the so-called 'core accretion' model. In this model a large planetary embryo formed first, mainly by two-body accretion. This is then followed by a period of inflow of nebular gas directly onto the growing planet. The core accretion model has an Achilles heel, namely the very first step. We have undertaken the most comprehensive study of this process to date. In this study we numerically integrate the orbits of a number of planetary embryos embedded in a swarm of planetesimals. In these experiments we have included: 1) aerodynamic gas drag, 2) collisional damping between planetesimals, 3) enhanced embryo cross-sections due to their atmospheres, 4) planetesimal fragmentation, and 5) planetesimal driven migration. We find that the gravitational interaction between the embryos and the planetesimals lead to the wholesale redistribution of material - regions are cleared of material and gaps open near the embryos. Indeed, in 90% of our simulations without fragmentation, the region near that embryos is cleared of planetesimals before much growth can occur. The remaining 10%, however, the embryos undergo a burst of outward migration that significantly increases growth. On timescales of ~100,000 years, the outer embryo can migrate ~6 AU and grow to roughly 30 Earth-masses. We also find that the inclusion of planetesimal fragmentation tends to inhibit growth.Comment: Accepted to AJ, 62 pages 11 figure

Stellar Activity in the Broad-Band Ultraviolet

The completion of the GALEX All-Sky Survey in the ultraviolet allows activity measurements to be acquired for many more stars than is possible with the limited sensitivity of ROSAT or the limited sky coverage of Chandra, XMM, or spectroscopic surveys for line emission in the optical or ultraviolet. We have explored the use of GALEX photometry as an activity indicator, using as a calibration sample stars within 50 pc, representing the field, and in selected nearby associations, representing the youngest stages of stellar evolution. We present preliminary relations between UV flux and the optical activity indicator R'_HK and between UV flux and age. We demonstrate that far-UV (FUV, 1350-1780{\AA}) excess flux is roughly proportional to R'_HK. We also detect a correlation between near-UV (NUV, 1780-2830{\AA}) flux and activity or age, but the effect is much more subtle, particularly for stars older than than ~0.5-1 Gyr. Both the FUV and NUV relations show large scatter, ~0.2 mag when predicting UV flux, ~0.18 dex when predicting R'_HK, and ~0.4 dex when predicting age. This scatter appears to be evenly split between observational errors in current state-of-the-art data and long-term activity variability in the sample stars.Comment: 37 pages, 12 figures. To appear in the Astronomical Journa