4,117 research outputs found
Stellar winds driven by multi-line scattering
This paper presents a model of a radiation-driven stellar wind with overlapping spectral lines. It is based on the Castor, Abbott, and Klein (CAK) theory. The presence of overlapping lines allows a photon to be scattered many times in different lines. The properties of the wind at any point depend on the wavelength-averaged intensity, which in turn depends on the structure of the wind. A self-consistent wind model is found. The mass loss rate does not saturate as line overlap becomes more pronounced, but continues to increase. The terminal velocity is much larger than in the CAK model, while the velocity law is shallower. This model might help explain the massive winds from Wolf-Rayet stars
An LED pulser for measuring photomultiplier linearity
A light-emitting diode (LED) pulser for testing the low-rate response of a
photomultiplier tube (PMT) to scintillator-like pulses has been designed,
developed, and implemented. This pulser is intended to simulate 80 ns full
width at half maximum photon pulses over the dynamic range of the PMT, in order
to precisely determine PMT linearity. This particular design has the advantage
that, unlike many LED test rigs, it does not require the use of multiple
calibrated LEDs, making it insensitive to LED gain drifts. Instead, a
finite-difference measurement is made using two LEDs which need not be
calibrated with respect to one another. These measurements give a better than
1% mapping of the response function, allowing for the testing and development
of particularly linear PMT bases.Comment: 5 pages, 5 figure
Paper Session I-D Leveraging Space for Improved Science Programs
This paper provides an overview of a program at Boeing\u27s Reusable Space Systems unit which was created and designed to show educators and students how science and engineering classes, lessons, and education can be made fun while teaching not only basic scientific principles, but how the principles may be applied in the real world. This program, called DiscoverE, for Discover Engineering, is an offshoot of the national program administered by the National Engineers Week organization which is comprised of several corporate affiliates, of which Boeing is one. The Discover Engineering program at Boeing-RSS consists of three basic segments and is a year-round activity. The three segments are an Educator Enrichment Day (EED), classroom visitations by Boeing engineers, and a Summer Science Camp. EED is normally scheduled to coincide with Engineers Week in February, and provides over 500 elementary and middle school educators with lessons, lesson plans, and access to resources with which they may not have been familiar. Science Camp is scheduled annually over three consecutive Fridays and Saturdays in July and August and typically has over 200 participants. Classroom visitations by engineers occur on an as requested basis year-round. The program leverages the expertise of the engineers, the corporate presence of Boeing, access to space related resources, and volunteerism to create a showcase program that, judging by reviews of the educators and students touched, is very successful. The program is described, workshop outlines and sample lessons are provided, and a student project which flew on the Space Shuttle is described
Virtual Reality and its Applications in the Mockup Process: A Case Study
Mockups are an important part of the construction process as they provide numerous benefits in both constructability review and aesthetic approval. Virtual Reality is an emerging technology that could prove to be a valuable addition to the mockup process. Many construction firms are attempting to incorporate virtual reality into any process they can --ranging from impressing owners in order to procure jobs to training employees so they can more adeptly adjust to field conditions. This paper will introduce virtual reality and some of its applications in the construction industry, specifically analyzing virtual reality and its applications in the mockup process via a case study. While the projects were met largely with success, they had their share of challenges in implementation. VR mockups proved valuable for aesthetic review purposes. They also improved the design-approval process which, in turn, reduced both cost and time. The technology was still met with challenges in implementation. The primary challenges were: aversion to the new technology, illness/nausea, hesitation about increased investment earlier in the project, and the reliance on available technology
Why Are You Really Winning and Losing Deals: A Customer Perspective on Determinants of Sales Failure
Understanding the determinants of sales success and sales failure has organization wide implications, ranging from an improved salesforce to improved corporate performance. However, a paucity of research on sales failure has resulted in an under-conceptualized field largely built on assumptions. This research proposes to overcome salesforce failure attribution biases by collecting data from the industrial buyer’s perspective. Thirty five post-mortem interviews with procurement decision makers from buying organizations were collected following a failed sales proposal. The context of these failed sales proposals was for multi-year industrial service key account contracts (\u3e$5 Million). The result of this naturalistic inquiry is a model which outlines the determinant attributes of sales failure: price, adaptability and relationship-potential. An experimental design was conducted following this exploratory research in order to test the derived drivers of sales failure and success, as well as provide a trade-off analysis of the three emergent sales proposal themes. Results indicate that a lack of adaptability has the strongest impact on the sales failure outcome variable, as well as buyer characteristics have a potentially moderating impact on the relative trade-off weights between price/adaptability and price/relationship-potential
The geology and petrogenesis of the southern closepet granite
The Archaean Closepet Granite is a polyphase body intruding the Peninsular Gneiss Complex and the associated supracrustal rocks. The granite out-crop runs for nearly 500 km with an approximate width of 20 to 25 km and cut across the regional metamorphic structure passing from granulite facies in the South and green schist facies in the north. In the amphibolite-granulite facies transition zone the granite is intimately mixed with migmatites and charnockite. Field observations suggests that anatexis of Peninsular gneisses led to the formation of granite melt, and there is a space relationship between migmatite formation, charnockite development and production and emplacement of granite magma. Based on texture and cross cutting relationships four major granite phases are recognized: (1) Pyroxene bearing dark grey granite; (2) Porphyritec granite; (3) Equigranular grey granite; and (4) Equigranular pink granite. The granite is medium to coarse grained and exhibit hypidiomorphic granular to porphyritic texture. The modal composition varies from granite granodiorite to quartz monzonite. Geochemical variation of the granite suite is consistent with either fractional crystallization or partial melting, but in both the cases biotite plus feldspar must be involved as fractionating or residual phases during melting to account trace element chemistry. The trace element data has been plotted on discriminant diagrams, where majority of samples plot in volcanic arc and within plate, tectonic environments. The granite show distinct REE patterns with variable total REE content. The REE patterns and overall abundances suggests that the granite suite represents a product of partial melting of crustal source in which fractional crystallization operated in a limited number of cases
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