Das Bauwerk als Informationscontainer in den frühen Phasen der Bauaufnahme - Ausgangspunkt für die Projektentwicklung und Entwurfsformulierung

Die digitale Unterstützung der Planungsprozesse ist ein aktueller Forschungs- und Arbeitsschwerpunkt der Professur Informatik in der Architektur (InfAR) und der Juniorprofessur Architekturinformatik der Fakultät Architektur an der Bauhaus-Universität Weimar. Verankert in dem DFG Sonderforschungsbereich 524 >Werkzeuge und Konstruktionen für die Revitalisierung von Bauwerken< entstehen Konzepte und Prototypen für eine fachlich orientierte Planungsunterstützung. In dem Beitrag wird ein Konzept und prototypische Realisierung für die durchgängige Unterstützung des gesamten Bauaufnahmeprozesses für Altbausubstanz vorgestellt und diskutiert. Der Fokus liegt auf der frühe Phase in der Bauaufnahme als ein Baustein in einer gesamtheitlichen IT-gestützen Planungsumgebung eingegangen. Durch gezielte Aufnahme planungsrelevanter Parameter und Auswertung hinsichtlich Wirtschaftlichkeit und Wiederverwendbarkeit bzw. der Variantenüberprüfung von Nutungskonzepten, werden gerade in dieser Phase wesentliche Entscheidungen für eine kostengünstige Planung getroffen werden. In der Veröffentlichung wird der Fokus auf folgende Punkte gesetzt: - Strukturierung und Aufnahme der Informationen während der Erstbegehung - Skizzenhafte Abbildung als Basis für die Formulierung erster Entwurfsintensionen/ Variantenuntersuchungen - Navigations- und Informationsumgebung - gezielte Auswertungsmöglichkeiten (bspw. Wirtschaftlichkeitsberechnung, Wiederverwendung von Bauteilen, Kalkulation von Abrissmengen

Kiloparsec-Scale Jets in FR I Radio Galaxies and the Gamma-Ray Background

We discuss the contribution of kiloparsec-scale jets in FR I radio galaxies to the diffuse gamma-ray background radiation. The analyzed gamma-ray emission comes from inverse-Compton scattering of starlight photon fields by the ultrarelativistic electrons whose synchrotron radiation is detected from such sources at radio, optical and X-ray energies. We find that these objects, under the minimum-power hypothesis (corresponding to a magnetic field of 300 muG in the brightest knots of these jets), can contribute about one percent to the extragalactic gamma-ray background measured by EGRET. We point out that this result already indicates that the magnetic fields in kpc-scale jets of low-power radio galaxies are not likely to be smaller than 10 muG on average, as otherwise the extragalactic gamma-ray background would be overproduced.Comment: 18 pages, 3 figures included. ApJ accepte

Is the EGRET source 3EG J1621+8203 the radio galaxy NGC 6251?

We discuss the nature of the unidentified EGRET source 3EG J1621+8203. In an effort to identify the gamma-ray source, we have examined X-ray images of the field from ROSAT PSPC, ROSAT HRI, and ASCA GIS. Of the several faint X-ray point sources in the error circle of 3EG J1621+8203, most are stars or faint radio sources, unlikely to be counterparts to the EGRET source. The most notable object in the gamma-ray error box is the bright FR I radio galaxy NGC 6251. If 3EG J1621+8203 corresponds to NGC 6251, then it would be the second radio galaxy to be detected in high energy gamma rays, after Cen A, which provided the first clear evidence of the detection above 100 MeV of an AGN with a large-inclination jet. If the detection of more radio galaxies by EGRET has been limited by its threshold sensitivity, there exists the exciting possibility that new high energy gamma-ray instruments, with much higher sensitivity, will detect a larger number of radio galaxies in the future.Comment: 7 pages, 6 figures. Accepted for publication in The Astrophysical Journal, August 2002 issu

Contribution from unresolved discrete sources to the Extragalactic Gamma-Ray Background (EGRB)

The origin of the extragalactic gamma-ray background (EGRB) is still an open question, even after nearly forty years of its discovery. The emission could originate from either truly diffuse processes or from unresolved point sources. Although the majority of the 271 point sources detected by EGRET (Energetic Gamma Ray Experiment Telescope) are unidentified, of the identified sources, blazars are the dominant candidates. Therefore, unresolved blazars may be considered the main contributor to the EGRB, and many studies have been carried out to understand their distribution, evolution and contribution to the EGRB. Considering that gamma-ray emission comes mostly from jets of blazars and that the jet emission decreases rapidly with increasing jet to line-of-sight angle, it is not surprising that EGRET was not able to detect many large inclination angle active galactic nuclei (AGNs). Though Fermi could only detect a few large inclination angle AGNs in the first three months' survey, it is expected to detect many such sources in the near future. Since non-blazar AGNs are expected to have higher density as compared to blazars, these could also contribute significantly to the EGRB. In this paper we discuss contributions from unresolved discrete sources including normal galaxies, starburst galaxies, blazars and off-axis AGNs to the EGRB.Comment: 11 pages, 4 figures, accepted for publication in RA

Neue Techniken in der Bestandserfassung

Die digitale Unterstützung der Planungsprozesse ist ein aktueller Forschungs- und Arbeitsschwerpunkt der Professur Informatik in der Architektur (InfAR) und der Juniorprofessur Architekturinformatik der Fakultät Architektur an der Bauhaus-Universität Weimar. Verankert in dem DFG Sonderforschungsbereich 524 >Werkzeuge und Konstruktionen für die Revitalisierung von Bauwerken< entstehen Konzepte und Prototypen für eine fachlich orientierte Planungsunterstützung. Als ein Teilaspekt wird in diesem Beitrag gezeigt, wie das Handaufmaß unter Einsatz modernen taktiler Erfassungsmethoden eine ganz neue Bedeutung für die Datenerfassung gewinnen kann. Das Potenzial der verschiedenen Verfahren zur Koordinatenbestimmung mit taktilen Werkzeugen wird evaluiert. Daraus wird eine Strategie entwickelt, die für die unterschiedlichen Notwendigkeiten im Planungsfortschritt den optimierten Einsatz der taktilen Erfassung in Kombination mit klassischen Erfassungsmethoden aufzeigt. Die Realisierbarkeit eines derartigen Konzeptes wird durch Fallstudien und mögliche Ablaufszenarien für einzelne Verfahren nachgewiesen. Durch die Integration taktiler Messverfahren in die Bestandserfassung kann erreicht werden, dass - relevante (Geometrie-) Informationen in ein umfassendes Bauwerksmodell integriert werden können, - die Bauaufnahme wieder im direkten Kontakt zum Bauaufnahmeobjekt erfolgen kann und - die Verfahren so einfach und leicht von allen Beteiligten eingesetzt werden können, um die Bauaufnahme und die Planung wieder miteinander zu verzahnen

Physical properties of Southern infrared dark clouds

It is commonly assumed that cold and dense Infrared Dark Clouds (IRDCs) likely represent the birth sites massive stars. Therefore, this class of objects gets increasing attention. To enlarge the sample of well-characterised IRDCs in the southern hemisphere, we have set up a program to study the gas and dust of southern IRDCs. The present paper aims at characterizing the continuuum properties of this sample of objects. We cross-correlated 1.2 mm continuum data from SIMBA@SEST with Spitzer/GLIMPSE images to establish the connection between emission sources at millimeter wavelengths and the IRDCs we see at 8 $\mu$m in absorption against the bright PAH background. Analysing the dust emission and extinction leads to a determination of masses and column densities, which are important quantities in characterizing the initial conditions of massive star formation. The total masses of the IRDCs were found to range from 150 to 1150 $\rm M_\odot$ (emission data) and from 300 to 1750 $\rm M_\odot$ (extinction data). We derived peak column densities between 0.9 and 4.6 $\times 10^{22}$ cm$^{-2}$ (emission data) and 2.1 and 5.4 $\times 10^{22}$ cm$^{-2}$ (extinction data). We demonstrate that the extinction method fails for very high extinction values (and column densities) beyond A$_{\rm V}$ values of roughly 75 mag according to the Weingartner & Draine (2001) extinction relation $R_{\rm V} = 5.5$ model B. The derived column densities, taking into account the spatial resolution effects, are beyond the column density threshold of 3.0 $\times 10^{23}$ cm$^{-2}$ required by theoretical considerations for massive star formation. We conclude that the values for column densities derived for the selected IRDC sample make these objects excellent candidates for objects in the earliest stages of massive star formation.Comment: Accepted for publication in Astronomy & Astrophysic

The James Clerk Maxwell Telescope Spectral Legacy Survey

Original article can be found at: http://www.journals.uchicago.edu/loi/pasp Copyright University of Chicago Press / AAS. DOI: 10.1086/511161Stars form in the densest, coldest, most quiescent regions of molecular clouds. Molecules provide the only probes that can reveal the dynamics, physics, chemistry, and evolution of these regions, but our understanding of the molecular inventory of sources and how this is related to their physical state and evolution is rudimentary and incomplete. The Spectral Legacy Survey (SLS) is one of seven surveys recently approved by the James Clerk Maxwell Telescope (JCMT) Board of Directors. Beginning in 2007, the SLS will produce a spectral imaging survey of the content and distribution of all the molecules detected in the 345 GHz atmospheric window (between 332 and 373 GHz) toward a sample of five sources. Our intended targets are a low-mass core (NGC 1333 IRAS 4), three high-mass cores spanning a range of star-forming environments and evolutionary states (W49, AFGL 2591, and IRAS 20126), and a photodissociation region (the Orion Bar). The SLS will use the unique spectral imaging capabilities of HARP-B/ACSIS (Heterodyne Array Receiver Programme B/Auto- Correlation Spectrometer and Imaging System) to study the molecular inventory and the physical structure of these objects, which span different evolutionary stages and physical environments and to probe their evolution during the star formation process. As its name suggests, the SLS will provide a lasting data legacy from the JCMT that is intended to benefit the entire astronomical community. As such, the entire data set (including calibrated spectral data cubes, maps of molecular emission, line identifications, and calculations of the gas temperature and column density) will be publicly available.Peer reviewe

The SCUBA-2 Ambitious Sky Survey: a catalogue of beam-sized sources in the Galactic longitude range 120° to 140°

The SCUBA-2 Ambitious Sky Survey (SASSy) is composed of shallow 850-µm imaging using the Sub-millimetre Common-User Bolometer Array 2 (SCUBA-2) on the James Clerk Maxwell Telescope. Here we describe the extraction of a catalogue of beam-sized sources from a roughly 120 deg2 region of the Galactic plane mapped uniformly (to an rms level of about 40 mJy), covering longitude 120° l b| IRAS Point Source Catalogue, to determine which sources discovered in this field might be new, and hence potentially cold regions at an early stage of star formation

An Unbiased Survey of 500 Nearby Stars for Debris Disks: A JCMT Legacy Program

We present the scientific motivation and observing plan for an upcoming detection survey for debris disks using the James Clerk Maxwell Telescope. The SCUBA-2 Unbiased Nearby Stars (SUNS) Survey will observe 500 nearby main sequence and sub-giant stars (100 of each of the A, F, G, K and M spectral classes) to the 850 micron extragalactic confusion limit to search for evidence of submillimeter excess, an indication of circumstellar material. The survey distance boundaries are 8.6, 16.5, 22, 25 and 45 pc for M, K, G, F and A stars, respectively, and all targets lie between the declinations of -40 deg to 80 deg. In this survey, no star will be rejected based on its inherent properties: binarity, presence of planetary companions, spectral type or age. This will be the first unbiased survey for debris disks since IRAS. We expect to detect ~125 debris disks, including ~50 cold disks not detectable in current shorter wavelength surveys. A substantial amount of complementary data will be required to constrain the temperatures and masses of discovered disks. High resolution studies will likely be required to resolve many of the disks. Therefore, these systems will be the focus of future observational studies using a variety of observatories to characterize their physical properties. For non-detected systems, this survey will set constraints (upper limits) on the amount of circumstellar dust, of typically 200 times the Kuiper Belt mass, but as low as 10 times the Kuiper Belt mass for the nearest stars in the sample (approximately 2 pc).Comment: 11 pages, 7 figures (3 color), accepted by the Publications of the Astronomical Society of the Pacifi

The Case for a Low Extragalactic Gamma-ray Background

Measurements of the diffuse extragalactic gamma-ray background (EGRB) are complicated by a strong Galactic foreground. Estimates of the EGRB flux and spectrum, obtained by modeling the Galactic emission, have produced a variety of (sometimes conflicting) results. The latest analysis of the EGRET data found an isotropic flux I_x=1.45+-0.05 above 100 MeV, in units of 10^-5 s^-1 cm^-2 sr^-1. We analyze the EGRET data in search for robust constraints on the EGRB flux, finding the gamma-ray sky strongly dominated by Galactic foreground even at high latitudes, with no conclusive evidence for an additional isotropic component. The gamma-ray intensity measured towards the Galactic poles is similar to or lower than previous estimates of I_x. The high latitude profile of the gamma-ray data is disk-like for 40<|b[deg]|<70, and even steeper for |b|>70; overall it exhibits strong Galactic features and is well fit by a simple Galactic model. Based on the |b|>40 data we find that I_x<0.5 at a 99% confidence level, with evidence for a much lower flux. We show that correlations with Galactic tracers, previously used to identify the Galactic foreground and estimate I_x, are not satisfactory; the results depend on the tracers used and on the part of the sky examined, because the Galactic emission is not linear in the Galactic tracers and exhibits spectral variations across the sky. The low EGRB flux favored by our analysis places stringent limits on extragalactic scenarios involving gamma-ray emission, such as radiation from blazars, intergalactic shocks and production of ultra-high energy cosmic rays and neutrinos. We suggest methods by which future gamma-ray missions such as GLAST and AGILE could indirectly identify the EGRB.Comment: Accepted for publication in JCAP. Increased sizes of polar regions examined, and added discussion of spectral data. Results unchange