@inproceedings{OhrnbergerWassermannRichter2006, author = {Ohrnberger, Matthias and Wassermann, Joachim and Richter, Gudrun}, title = {Automatic detection and classification of seismic signals for monitoring purposes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7294}, year = {2006}, abstract = {Interdisziplin{\"a}res Zentrum f{\"u}r Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006}, language = {en} } @inproceedings{IgnaceGayley2007, author = {Ignace, R. and Gayley, K. G.}, title = {Circumstellar Magnetic Field Diagnostics from Line Polarization}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18066}, year = {2007}, language = {en} } @inproceedings{MillsHealey2006, author = {Mills, Gregory J. and Healey, Patrick G. T.}, title = {Clarifying spatial descriptions : local and global effects on semantic co-ordination}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-10414}, year = {2006}, abstract = {A key problem for models of dialogue is to explain the mechanisms involved in generating and responding to clarification requests. We report a 'Maze task' experiment that investigates the effect of 'spoof' clarification requests on the development of semantic co-ordination. The results provide evidence of both local and global semantic co-ordination phenomena that are not captured by existing dialogue co-ordination models.}, language = {en} } @inproceedings{Reimer2007, author = {Reimer, A.}, title = {Clumping effects on non-thermal particle spectra in massive star systems}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18246}, year = {2007}, abstract = {Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.}, language = {en} } @inproceedings{LiermannHamann2007, author = {Liermann, A. and Hamann, Wolf-Rainer}, title = {Clumping in Galactic WN stars : a comparison of mass loss rates from UV/optical \& radio diagnostics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17816}, year = {2007}, abstract = {The mass loss rates and other parameters for a large sample of Galactic WN stars have been revised by Hamann et al. (2006), using the most up-to date Potsdam Wolf-Rayet (PoWR) model atmospheres. For a sub-sample of these stars exist measurements of their radio free-free emission. After harmonizing the adopted distance and terminal wind velocities, we compare the mass loss rates obtained from the two diagnostics. The differences are discussed as a possible consequence of different clumping contrast in the line-forming and radio-emitting regions.}, language = {en} } @inproceedings{OPUS4-1574, title = {Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007}, editor = {Hamann, Wolf-Rainer and Feldmeier, Achim and Oskinova, Lida}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-33-1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13981}, pages = {254}, year = {2007}, abstract = {Stellar winds play an important role for the evolution of massive stars and their cosmic environment. Multiple lines of evidence, coming from spectroscopy, polarimetry, variability, stellar ejecta, and hydrodynamic modeling, suggest that stellar winds are non-stationary and inhomogeneous. This is referred to as 'wind clumping'. The urgent need to understand this phenomenon is boosted by its far-reaching implications. Most importantly, all techniques to derive empirical mass-loss rates are more or less corrupted by wind clumping. Consequently, mass-loss rates are extremely uncertain. Within their range of uncertainty, completely different scenarios for the evolution of massive stars are obtained. Settling these questions for Galactic OB, LBV and Wolf-Rayet stars is prerequisite to understanding stellar clusters and galaxies, or predicting the properties of first-generation stars. In order to develop a consistent picture and understanding of clumped stellar winds, an international workshop on 'Clumping in Hot Star Winds' was held in Potsdam, Germany, from 18. - 22. June 2007. About 60 participants, comprising almost all leading experts in the field, gathered for one week of extensive exchange and discussion. The Scientific Organizing Committee (SOC) included John Brown (Glasgow), Joseph Cassinelli (Madison), Paul Crowther (Sheffield), Alex Fullerton (Baltimore), Wolf-Rainer Hamann (Potsdam, chair), Anthony Moffat (Montreal), Stan Owocki (Newark), and Joachim Puls (Munich). These proceedings contain the invited and contributed talks presented at the workshop, and document the extensive discussions.}, language = {en} } @inproceedings{PulsMarkovaNajarroetal.2007, author = {Puls, Joachim and Markova, N. and Najarro, F. and Hanson, M. M.}, title = {Clumping in O-star winds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17683}, year = {2007}, abstract = {We review various diagnostics of clumping in O-star winds, with special emphasis on its radial stratification. Implications and problems are discussed, and promising NIR methods are presented.}, language = {en} } @inproceedings{BouretLanzHillieretal.2007, author = {Bouret, J.-C. and Lanz, T. and Hillier, D. J. and Foellmi, C.}, title = {Clumping in O-type Supergiants}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17662}, year = {2007}, abstract = {We have analyzed the spectra of seven Galactic O4 supergiants, with the NLTE wind code CMFGEN. For all stars, we have found that clumped wind models match well lines from different species spanning a wavelength range from FUV to optical, and remain consistent with Hα data. We have achieved an excellent match of the P V λλ1118, 1128 resonance doublet and N IV λ1718, as well as He II λ4686 suggesting that our physical description of clumping is adequate. We find very small volume filling factors and that clumping starts deep in the wind, near the sonic point. The most crucial consequence of our analysis is that the mass loss rates of O stars need to be revised downward significantly, by a factor of 3 and more compared to those obtained from smooth-wind models.}, language = {en} } @inproceedings{UrbanejaKudritzkiPuls2007, author = {Urbaneja, M. A. and Kudritzki, R.-P. and Puls, Joachim}, title = {Clumping in the winds of O-type CSPNs}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17801}, year = {2007}, abstract = {Recent studies of massive O-type stars present clear evidences of inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary nebulae (CSPNs) are in some ways the low mass-low luminosity analogous of those massive stars. In this contribution, we present preliminary results of our on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic CSPNs. Particular emphasis will be given to the clumping factors derived by means of optical lines (Hα and Heii 4686) and "classic" FUV (and UV) lines.}, language = {en} } @inproceedings{BandaGallagher2010, author = {Banda, Gourinath and Gallagher, John P.}, title = {Constraint-based abstraction of a model checker for infinite state systems}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-41516}, year = {2010}, abstract = {Abstract interpretation-based model checking provides an approach to verifying properties of infinite-state systems. In practice, most previous work on abstract model checking is either restricted to verifying universal properties, or develops special techniques for temporal logics such as modal transition systems or other dual transition systems. By contrast we apply completely standard techniques for constructing abstract interpretations to the abstraction of a CTL semantic function, without restricting the kind of properties that can be verified. Furthermore we show that this leads directly to implementation of abstract model checking algorithms for abstract domains based on constraints, making use of an SMT solver.}, language = {en} }