13,014 research outputs found

    Tensor-Scalar Torsion

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    A theory of gravity with torsion is examined in which the torsion tensor is constructed from the exterior derivative of an antisymmetric rank two potential plus the dual of the gradient of a scalar field. Field equations for the theory are derived by demanding that the action be stationary under variations with respect to the metric, the antisymmetric potential, and the scalar field. A material action is introduced and the equations of motion are derived. The correct conservation law for rotational angular momentum plus spin is observed to hold in this theory.Comment: 10 pages, LaTeX, Mod. Phys. Lett. A accepte

    Ride quality systems for commuter aircraft

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    The state-of-the-art in Active Ride Augmentation, specifically in terms of its feasibility for commuter aircraft applications. A literature survey was done, and the principal results are presented here through discussion of different Ride Quality Augmentation System (RQAS) designs and advances in related technologies. Recommended follow-on research areas are discussed, and a preliminary RQAS configuration for detailed design and development is proposed

    Covariance analysis of the airborne laser ranging system

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    The requirements and limitations of employing an airborne laser ranging system for detecting crustal shifts of the Earth within centimeters over a region of approximately 200 by 400 km are presented. The system consists of an aircraft which flies over a grid of ground deployed retroreflectors, making six passes over the grid at two different altitudes. The retroreflector baseline errors are assumed to result from measurement noise, a priori errors on the aircraft and retroreflector positions, tropospheric refraction, and sensor biases

    Advocacy Journalism, the Politics of Humanitarian Intervention and the Syrian War

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    Since 2011, the international media have done much to highlight the suffering of civilians in the on-going war in Syria, through innovative forms of reporting such as VR journalism and news games. However, by the end of 2016, questions were being raised about a number of high-profile news stories, such as the use of chemical weapons, the role of the ‘White Helmets’ relief workers and the bombing of Aleppo and other cities. Amid the claims and counter- claims of propaganda and ‘fake news’, news audiences glimpsed shifting and clashing explanatory framings of the Syrian war. A conflict that had initially been understood against the background of the ‘Arab Spring’ began to be seen as complicated by sectarian religious tensions, the rise of Islamic State, opaque factional and regional alliances, and international tensions reminiscent of the Cold War. An imperative to establish a moral framework for the story seemed to preclude more complex and searching questions about the motivations and actions of local and international actors

    Experimental and numerical study of error fields in the CNT stellarator

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    Sources of error fields were indirectly inferred in a stellarator by reconciling computed and numerical flux surfaces. Sources considered so far include the displacements and tilts (but not the deformations, yet) of the four circular coils featured in the simple CNT stellarator. The flux surfaces were measured by means of an electron beam and phosphor rod, and were computed by means of a Biot-Savart field-line tracing code. If the ideal coil locations and orientations are used in the computation, agreement with measurements is poor. Discrepancies are ascribed to errors in the positioning and orientation of the in-vessel interlocked coils. To that end, an iterative numerical method was developed. A Newton-Raphson algorithm searches for the coils' displacements and tilts that minimize the discrepancy between the measured and computed flux surfaces. This method was verified by misplacing and tilting the coils in a numerical model of CNT, calculating the flux surfaces that they generated, and testing the algorithm's ability to deduce the coils' displacements and tilts. Subsequently, the numerical method was applied to the experimental data, arriving at a set of coil displacements whose resulting field errors exhibited significantly improved quantitative and qualitative agreement with experimental results.Comment: Special Issue on the 20th International Stellarator-Heliotron Worksho

    Assortative mating and artificial selection : a second appraisal

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    Fermion Helicity Flip Induced by Torsion Field

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    We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter

    Design of a digital ride quality augmentation system for commuter aircraft

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    Commuter aircraft typically have low wing loadings, and fly at low altitudes, and so they are susceptible to undesirable accelerations caused by random atmospheric turbulence. Larger commercial aircraft typically have higher wing loadings and fly at altitudes where the turbulence level is lower, and so they provide smoother rides. This project was initiated based on the goal of making the ride of the commuter aircraft as smooth as the ride experienced on the major commercial airliners. The objectives of this project were to design a digital, longitudinal mode ride quality augmentation system (RQAS) for a commuter aircraft, and to investigate the effect of selected parameters on those designs

    Common Graphics Library (CGL). Volume 1: LEZ user's guide

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    Users are introduced to and instructed in the use of the Langley Easy (LEZ) routines of the Common Graphics Library (CGL). The LEZ routines form an application independent graphics package which enables the user community to view data quickly and easily, while providing a means of generating scientific charts conforming to the publication and/or viewgraph process. A distinct advantage for using the LEZ routines is that the underlying graphics package may be replaced or modified without requiring the users to change their application programs. The library is written in ANSI FORTRAN 77, and currently uses a CORE-based underlying graphics package, and is therefore machine independent, providing support for centralized and/or distributed computer systems
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