6,776 research outputs found

    Gaia ventures business plan building blocks

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    http://deepblue.lib.umich.edu/bitstream/2027.42/96951/1/MBA_WatsonF_1996Final.pd

    Configurations and relative efficiencies of shrimp trawls employed in southeastern United States waters

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    Common shrimp trawl designs employed in the southeastern United States shrimp fishery are the flat, balloon, semiballoon, jib, and super X-3. Recent innovations in trawl design and rigging, including the twin trawl rigging and tongue trawl design, have improved the efficiency of shrimp trawling gear. A description of the construction techniques for the different designs indicate differences which affect gear performance. Measurements of horizontal spread and vertical opening for 76 trawl configurations indicate the relative efficiencies of the different designs. Maximum horizontal spreading efficiency was achieved by the "twin" and "tongue" trawl designs followed by the super X-3, jib, balloon, and semiballoon designs. Designs having the greatest vertical openings were the tongue and flat trawl designs followed by the semiballoon. Maximum total gape dimension was demonstrated by the "Mongoose" tongue trawl. Comparison of trawl spreading efficiency and door area to headrope length ratio indicates that a range of 70-80 in square (per door) of door area is required for each foot of trawl headrope length for maximum efficiency with conventional trawl designs and 66-75 in square per foot of headrope for tongue trawl designs. (PDF file contains 18 pages.

    Strong Upper Limits on Sterile Neutrino Warm Dark Matter

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    Sterile neutrinos are attractive dark matter candidates. Their parameter space of mass and mixing angle has not yet been fully tested despite intensive efforts that exploit their gravitational clustering properties and radiative decays. We use the limits on gamma-ray line emission from the Galactic Center region obtained with the SPI spectrometer on the INTEGRAL satellite to set new constraints, which improve on the earlier bounds on mixing by more than two orders of magnitude, and thus strongly restrict a wide and interesting range of models.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in Physical Review Letter

    The selection of a suitable maintenance strategy for wind turbines.

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    Common maintenance strategies applied to wind turbines include 'Time-Based' which involves carrying out maintenance tasks at predetermined regular-intervals and 'Failur-Based' which entails using a wind turbine until it fails. However, the consequence of failure of critical components limits the adequacy of these strategies to support the current commercial drivers of the wind industry. Reliability-Centred Maintenance (RCM) is a technique used mostly to select appropriate maintenance strategies for physical assets. In this paper, a hybrid of an RCM approach and Asset Life-Cycle Analysis technique is applied to Horizontal-Axis Wind Turbines to identify possible failure modes, causes and the resultant effects on system operation. The failure consequences of critical compenents are evaluated and expressed in financial terms. Suitable Condition-Based Maintenance activities are identified and assessed over the life cycle of wind turbines to maximise the return on investment in wind farms

    Reviews

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    The following publications have been reviewed by the mentioned authors;The Art of Print Making by Erich Rhein, reviewed by John LancasterDevelopments in Art Teaching by Terence Wooff, reviewed by John LancasterResources by Jack Bainbridge, reviewed by Michael SayerPower by Jack Bainbridge, reviewed by Michael SayerThe Potter's Complete Book of Clay and Glazes by James Chappell, reviewed by Michael PaffardWriting and Illuminating Lettering by Edward Johnston, reviewed by John LancasterBasic Mathematics for Technicians by C. W. Schofield, reviewed by F. R. WatsonDesign and Technology - Plastics by R. Millett, reviewed by Michael SayerObjective and Completion Tests in CSE Woodwork Theory by Ernest Clarke, reviewed by Denis TabernerObjectice and Completion Tests in CSE Metalwork Theory by Ernest Clarke, reviewed by Denis Taberne

    Human-Centered Design Using System Modeling Language

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    The human user is important to consider during system design. However, common system design models, such as the system modeling language, typically represent human users and operators as external actors, rather than as internal to the system. This research presents a method for integrating human considerations into system models through human-centered design. A specific system is selected to serve as the case study for demonstrating the methodology. The sample system is analyzed to identify the task and information flow. Then, both system- and human-centered diagrams are separately created to represent different viewpoints of the system. These diagrams are compared and analyzed, and new diagrams are created that incorporate both system and human considerations into one concordant representation of the system model. These new views allow systems engineers and human factors engineers to effectively communicate the role of the user during early system design trades

    On the forward cone quantization of the Dirac field in "longitudinal boost-invariant" coordinates with cylindrical symmetry

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    We obtain a complete set of free-field solutions of the Dirac equation in a (longitudinal) boost-invariant geometry with azimuthal symmetry and use these solutions to perform the canonical quantization of a free Dirac field of mass MM. This coordinate system which uses the 1+1 dimensional fluid rapidity η=1/2ln[(tz)/(t+z)]\eta = 1/2 \ln [(t-z)/(t+z)] and the fluid proper time τ=(t2z2)1/2\tau = (t^2-z^2)^{1/2} is relevant for understanding particle production of quarks and antiquarks following an ultrarelativistic collision of heavy ions, as it incorporates the (approximate) longitudinal "boost invariance" of the distribution of outgoing particles. We compare two approaches to solving the Dirac equation in curvilinear coordinates, one directly using Vierbeins, and one using a "diagonal" Vierbein representation

    Recurrent \u3cem\u3eStreptococcus equi\u3c/em\u3e subsp. \u3cem\u3ezooepidemicus\u3c/em\u3e Bacteremia in an Infant

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    We describe a case of an infant with recurrent bacteremia caused by Streptococcus equi subsp. zooepidemicus, likely transmitted from mother to infant. Our case highlights the importance of an epidemiological history and molecular diagnostics in ascertaining insights into transmission, pathogenesis, and optimal management
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