30,454 research outputs found

    Helical tape forming device

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    Using a device that is not limited to a minimum thickness or width-to-thickness ratio, a very thin metal tape or ribbon is formed into a continuous flat wound helical coil. The device imparts the desired circular shape by squeeze rolling it with an unequal force across its width

    Low friction magnetic recording tape Patent

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    Development of low friction magnetic recording tap

    The Effects of Age on Red Giant Metallicities Derived from the Near-Infrared Ca II Triplet

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    We have obtained spectra with resolution 2.5 Angstroms in the region 7500-9500 Angstroms for 116 red giants in 5 Galactic globular clusters and 6 old open clusters (5 with published metallicities, and one previously unmeasured). The signal-to-noise ranges from 20 to 85. We measure the equivalent widths of the infrared Ca II triplet absorption lines in each stars and compare to cluster metallicities taken from the literature. With globular cluster abundances on the Carretta & Gratton scale, and open cluster abundances taken from the compilation of Friel and collaborators, we find a linear relation between [Fe/H] and Ca II line strength spanning the range -2 < [Fe/H] < -0.2 and ages from 2.5 - 13 Gyr. No evidence for an age effect on the metallicity calibration is observed. Using this calibration, we find the metallicity of the old open cluster Trumpler 5 to be [Fe/H] = -0.56 +/-0.11. Considering the 10 clusters of known metallicity shifted to a common distance and reddening, we find that the additional metallicity error introduced by the variation of horizontal branch/red clump magnitude with metallicity and age is of order +/-0.05 dex, which can be neglected in comparison to the intrinsic scatter in our method. The results are discussed in the context of abundance determinations for red giants in Local Group galaxies.Comment: Accepted by MNRAS; 21 pages in LaTeX MNRAS style, 6 tables, 6 figure

    Hands on XBRL and Industry Analysis

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    The newest important technology available to accountants and other business executives is eXtensible Business Reporting Language (XBRL). XBRL is a publicly shared computer language that allows us to electronically report, access, and gather financial information. XBRL is now used by accountants to report their financial information, and by analysts to access financial information of other publicly traded companies. It is critical that our students understand and are able to use XBRL

    Reconnaissance Survey of Benthonic Foraminifera from Baffin Island Fiord Environments

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    Benthonic foraminiferal assemblages in 63 grab samples collected in Baffin Island fiord basin environments (67-800 m) are dominated by arenaceous species such as Textularia earlandi and Spiroplectammina biformis. These forms reflect the influence of cold (&lt;=0.0 degrees C) arctic water conditions. Incursions of comparatively warm and saline Atlantic bottom water is marked in the deepest part of some fiord basins by the distribution of several calcareous species such as Melonis zaandamae and Nonionella atlantica. The highest living calcareous species population densities are associated primarily with fiord sills and with inner shelf environments near the mouths of fiords. Conversely, the patchy distribution and low percentages of many calcareous species found in basin sediments suggest passive transport of perhaps both living specimens and empty tests from shallow nearshore (endemic) environments or their occupation of deep basin transitional environments that mark the change from Atlantic to arctic water masses.Key words: foraminifera, Baffin Island, Fiords, arenaceous foraminifera, calcareous foraminiferaMots cl&eacute;s: foraminif&egrave;res, &icirc;le de Baffin, fjords, foraminif&egrave;res ar&eacute;nac&eacute;s, foraminif&egrave;res calcaire

    Small scale model static acoustic investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

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    A static acoustic and propulsion test of a small radius Jacobs-Hurkamp and a large radius Flex Flap combined with four upper surface blowing (USB) nozzles was performed. Nozzle force and flow data, flap trailing edge total pressure survey data, and acoustic data were obtained. Jacobs-Hurkamp flap surface pressure data, flow visualization photographs, and spoiler acoustic data from the limited mid-year tests are reported. A pressure ratio range of 1.2 to 1.5 was investigated for the USB nozzles and for the auxiliary blowing slots. The acoustic data were scaled to a four-engine STOL airplane of roughly 110,000 kilograms or 50,000 pounds gross weight, corresponding to a model scale of approximately 0.2 for the nozzles without deflector. The model nozzle scale is actually reduced to about .17 with deflector although all results in this report assume 0.2 scale factor. Trailing edge pressure surveys indicated that poor flow attachment was obtained even at large flow impingement angles unless a nozzle deflector plate was used. Good attachment was obtained with the aspect ratio four nozzle with deflector, confirming the small scale wind tunnel tests

    Baryon Acoustic Oscillations in 2D: Modeling Redshift-space Power Spectrum from Perturbation Theory

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    We present an improved prescription for matter power spectrum in redshift space taking a proper account of both the non-linear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the non-linear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1~2%, and the growth rate parameter by ~5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription of redshift-space power spectrum including the non-linear corrections can be used as an accurate theoretical template for anisotropic BAOs.Comment: 18 pages, 10 figure

    Improving the Price of Anarchy for Selfish Routing via Coordination Mechanisms

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    We reconsider the well-studied Selfish Routing game with affine latency functions. The Price of Anarchy for this class of games takes maximum value 4/3; this maximum is attained already for a simple network of two parallel links, known as Pigou's network. We improve upon the value 4/3 by means of Coordination Mechanisms. We increase the latency functions of the edges in the network, i.e., if ℓe(x)\ell_e(x) is the latency function of an edge ee, we replace it by ℓ^e(x)\hat{\ell}_e(x) with ℓe(x)≤ℓ^e(x)\ell_e(x) \le \hat{\ell}_e(x) for all xx. Then an adversary fixes a demand rate as input. The engineered Price of Anarchy of the mechanism is defined as the worst-case ratio of the Nash social cost in the modified network over the optimal social cost in the original network. Formally, if \CM(r) denotes the cost of the worst Nash flow in the modified network for rate rr and \Copt(r) denotes the cost of the optimal flow in the original network for the same rate then [\ePoA = \max_{r \ge 0} \frac{\CM(r)}{\Copt(r)}.] We first exhibit a simple coordination mechanism that achieves for any network of parallel links an engineered Price of Anarchy strictly less than 4/3. For the case of two parallel links our basic mechanism gives 5/4 = 1.25. Then, for the case of two parallel links, we describe an optimal mechanism; its engineered Price of Anarchy lies between 1.191 and 1.192.Comment: 17 pages, 2 figures, preliminary version appeared at ESA 201
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