23,281 research outputs found
Computational fluid dynamics research at the United Technologies Research Center requiring supercomputers
An overview of research activities at the United Technologies Research Center (UTRC) in the area of Computational Fluid Dynamics (CFD) is presented. The requirement and use of various levels of computers, including supercomputers, for the CFD activities is described. Examples of CFD directed toward applications to helicopters, turbomachinery, heat exchangers, and the National Aerospace Plane are included. Helicopter rotor codes for the prediction of rotor and fuselage flow fields and airloads were developed with emphasis on rotor wake modeling. Airflow and airload predictions and comparisons with experimental data are presented. Examples are presented of recent parabolized Navier-Stokes and full Navier-Stokes solutions for hypersonic shock-wave/boundary layer interaction, and hydrogen/air supersonic combustion. In addition, other examples of CFD efforts in turbomachinery Navier-Stokes methodology and separated flow modeling are presented. A brief discussion of the 3-tier scientific computing environment is also presented, in which the researcher has access to workstations, mid-size computers, and supercomputers
On Mirror Symmetry in Three Dimensional Abelian Gauge Theories
We present an identity relating the partition function of N=4 supersymmetric
QED to that of its dual under mirror symmetry. The identity is a generalized
Fourier transform. Many known properties of abelian theories can be derived
from this formula, including the mirror transforms for more general gauge and
matter content. We show that N=3 Chern-Simons QED and N=4 QED with BF-type
couplings are conformal field theories with exactly marginal couplings. Mirror
symmetry acts on these theories as strong-weak coupling duality. After
identifying the mirror of the gauge coupling (sometimes called the ``magnetic
coupling'') we construct a theory which is exactly mirror -- at all scales --
to N=4 SQED. We also study vortex-creation operators in the large limit.Comment: 23 pages; Revision includes a new section discussing multiple mirror
transforms of a single theory ("piecewise" mirror transforms.
Between dirigism and laissez-faire: Effects of implementing the science policy priority for biotechnology in the Netherlands
A Program Committee Biotechnology was established in the Netherlands for the period 1981¿1985, to stimulate biotechnological research and its contribution to innovation. Effects of its activities on researchers and on the research system have been measured in terms of recognition of and commitment to the priorities and approaches of the Program Committee. Results from the questionnaire survey and the interviews are presented, and are used to assess the implementation strategy of the committee and the dynamics of orientation of researchers to new priorities. A consciously orchestrating strategy, with some accommodation to the interests of the field, appears to be productive. This may be a generally useful middle course between dirigism and laissez-faire, because it exploits the leverage that resides in the strategies of scientists to mobilize resources for their work
Knight Shift in the FFLO State of a Two-Dimensional D-Wave Superconductor
We report on the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in
two-dimensional d-wave superconductors with magnetic field parallel to the
superconducting planes. This state occurs at high magnetic field near the
Pauli-Clogston limit and is a consequence of the competition between the pair
condensation and Zeeman energy. We use the quasiclassical theory to
self-consistently compute the spatially nonuniform order parameter. Our
self-consistent calculations show that the FFLO state of a d-wave order
parameter breaks translational symmetry along preferred directions. The
orientation of the nodes in real space is pinned by the nodes of the basis
function in momentum space. Here, we present results for the Knight shift and
discuss the implications for recent nuclear magnetic resonance measurements on
CeCoIn5.Comment: 2 pages, 3 figures: LT-24 Conference, Orlando, Aug. 2005; to appear
in AIP Conference Proceeding
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