2,022 research outputs found

    Evidence that widespread star formation may be underway in G0.253+016, "The Brick"

    Get PDF
    Image cubes of differential column density as a function of dust temperature are constructed for Galactic Centre molecular cloud G0.253+0.016 ("The Brick") using the recently described PPMAP procedure. The input data consist of continuum images from the Herschel Space Telescope in the wavelength range 70-500 μ\mum, supplemented by previously published interferometric data at 1.3 mm wavelength. While the bulk of the dust in the molecular cloud is consistent with being heated externally by the local interstellar radiation field, our image cube shows the presence, near one edge of the cloud, of a filamentary structure whose temperature profile suggests internal heating. The structure appears as a cool (14\sim 14 K) tadpole-like feature, 6\sim 6 pc in length, in which is embedded a thin spine of much hotter (\sim 40-50 K) material. We interpret these findings in terms of a cool filament whose hot central region is undergoing gravitational collapse and fragmentation to form a line of protostars. If confirmed, this would represent the first evidence of widespread star formation having started within this cloud.Comment: 5 pages, 4 figures; accepted for publication in MNRAS Letter

    Merging LANDSAT Derived Land Covers into Quad-referenced Geographic Information Systems

    Get PDF
    An approach for merging multiscene LANDSAT data bases into existing geographic information systems having 5-second or smaller cells is described. The approach uses the output from the State of Maryland's UNIVAC 1180-based LANDSAT classification program ASTEP (Algorithm Simulation Test and Evaluation) developed by NASA. The structure of the technique was designed to address the problems that emerged as part of the LANDSAT classification of the 64,000 square mile Chesapeake water shed involving twelve scenes. The removal of overlap among adjacent scenes, the crossreferencing of ground control points, and the isolation of the appropriate pixels from the LANDSAT data base for subsequent positioning into a file containing ancillary data referenced to a specific USGS 7 1/2 minute quadrangle sheet are described. Examples illustrate the clustering of classified LANDSAT pixels to define the dominant land use for each of 8,100 cells within a series of quadrangle sheets distributed over the State of Maryland. The approach uses a hard copy terminal tied to an ASTEP algorithm through telephone lines. A coordinate digitizing board for inputing the position of ground control points is also valuable, although manual measurements are possible. The approach is quite efficient and should be especially attractive for use on regional scale studies

    A comparison between conventional and LANDSAT based hydrologic modeling: The Four Mile Run case study

    Get PDF
    Models designed to support the hydrologic studies associated with urban water resources planning require input parameters that are defined in terms of land cover. Estimating the land cover is a difficult and expensive task when drainage areas larger than a few sq. km are involved. Conventional and LANDSAT based methods for estimating the land cover based input parameters required by hydrologic planning models were compared in a case study of the 50.5 sq. km (19.5 sq. mi) Four Mile Run Watershed in Virginia. Results of the study indicate that the LANDSAT based approach is highly cost effective for planning model studies. The conventional approach to define inputs was based on 1:3600 aerial photos, required 110 man-days and a total cost of 14,000.TheLANDSATbasedapproachrequired6.9mandaysandcost14,000. The LANDSAT based approach required 6.9 man-days and cost 2,350. The conventional and LANDSAT based models gave similar results relative to discharges and estimated annual damages expected from no flood control, channelization, and detention storage alternatives

    Materijal matrica za tlačno lijevanje

    Get PDF
    In the contribution the stress of die materials of thermal fatigue is defined and material life is derived theoretically and compared with the measured values. The important properties of the die materials as thermal conductivity, coefficient of thermal expansivity, modulus of elasticity and mechanical properties are described. Binding to it single die materials as carbon steels and chrome-tungsten steels are analyzed. As the perspective die material for pressure die casting of ferrous metals appears molybdenum with regard to advantageous properties.U članku je definirano naprezanje materijala pri toplinskom umoru i izveden teorijski životno (radno) vrijeme materijala te uspoređene sa izmjerenim vrijednostima. Opisana su važna svojstva materijala, kao što je toplinska vodljivost, koefi cijent toplinske rastegljivosti, modul elastičnosti i mehanička svojstva. U nastavku su analizirani materijali kao što su ugljični čelici te krom-volframovi čelici. Kao perspektivni materijal za tlačno lijevanje željeznih slitina se pojavljuje molibdan sa prestižnim svojstvima

    Materials on dies for pressure die casting

    Get PDF
    In the contribution the stress of die materials of thermal fatigue is defi ned and material life is derived theoretically and compared with the measured values. The important properties of the die materials as thermal conductivity, coeffi cient of thermal expansivity, modulus of elasticity and mechanical properties are described. Binding to it single die materials as carbon steels and chrome-tungsten steels are analyzed. As the perspective die material for pressure die casting of ferrous metals appears molybdenum with regard to advantageous properties

    Void-mediated formation of Sn quantum dots in a Si matrix

    Get PDF
    Atomic scale analysis of Sn quantum dots (QDs) formed during the molecular beam-epitaxy (MBE) growth of Sn_xSi_(1−x) (0.05 ⩽ x ⩽ 0.1) multilayers in a Si matrix revealed a void-mediated formation mechanism. Voids below the Si surface are induced by the lattice mismatch strain between Sn_xSi_(1−x) layers and Si, taking on their equilibrium tetrakaidecahedron shape. The diffusion of Sn atoms into these voids leads to an initial rapid coarsening of quantum dots during annealing. Since this formation process is not restricted to Sn, a method to grow QDs may be developed by controlling the formation of voids and the diffusion of materials into these voids during MBE growth

    IFRS: Approaching A State Of Convergence

    Get PDF
    In this paper we will discuss the underlying differences that currently exist between IFRS and US GAAP. Our paper is presented with the belief that convergence is within reach at this point, and no longer an unfeasible event. The systematic rules-based approach and the conceptual principles-based approach are important models for this paper, and we refer to them when discussing the differences and developing our beliefs. The differences that we have chosen to discuss are ones, we feel, that could lead to comparability complications once IFRS is acceptable among US firms and International firms with US subsidiaries. Areas of concern involve items regarding financial statement presentation, revenue recognition, expense recognition, assets, and liabilities. Although there are a great deal of similarities between the US GAAP and IFRS reporting requirements, the specific items presented within this paper need to be addressed before commonly accepted accounting standards are used among encompassing countries

    Star Electronics, Inc.: An Excel Based Case Using Financial Statement Analysis To Detect Fraud

    Get PDF
    The demand for forensic accounting within the corporate world is continually increasing. The services performed by forensic accountants help detect and prevent fraud within companies. This case is a study of forensic accounting that utilizes fraud methodology and detection techniques through a simulation engagement. Those who complete this case will proceed through a series of procedures that will lead to the formulation of potential fraudulent activity within the discussed company. The addressed procedures include: understanding the business, determining the areas that may be susceptible to fraud, performing analytical procedures to detect fraud, and creating a report to the board of directors as a follow up to any potential red flags found during the performed testing
    corecore