33,228 research outputs found
Bonded joint and method
An improved joint is described for reducing the peak shear stress in adhesive bonds when adhesives are used to bond two materials which are in a lapped relationship and which differ in value of modulus of elasticity. An insert placed between the adhesive and one of the two materials acts to cushion the discontinuity of material stiffness thereby reducing the peak shear stress in the adhesive bond
Symplectic structure for elastic and chiral conducting cosmic string models
This article is based on the covariant canonical formalism and corresponding
symplectic structure on phase space developed by Witten, Zuckerman and others
in the context of field theory. After recalling the basic principles of this
procedure, we construct the conserved bilinear symplectic current for generic
elastic string models. These models describe current carrying cosmic strings
evolving in an arbitrary curved background spacetime. Particular attention is
paid to the special case of the chiral string for which the worldsheet current
is null. Different formulations of the chiral string action are discussed in
detail, and as a result the integrability property of the chiral string is
clarified.Comment: 18 page
Transonic Elastic Model for Wiggly Goto-Nambu String
The hitherto controversial proposition that a ``wiggly" Goto-Nambu cosmic
string can be effectively represented by an elastic string model of exactly
transonic type (with energy density inversely proportional to its tension
) is shown to have a firm mathematical basis.Comment: 8 pages, plain TeX, no figure
NASTRAN data generation of helicopter fuselages using interactive graphics
The development and implementation of a preprocessor system for the finite element analysis of helicopter fuselages is described. The system utilizes interactive graphics for the generation, display, and editing of NASTRAN data for fuselage models. It is operated from an IBM 2250 cathode ray tube (CRT) console driven by an IBM 370/145 computer. Real time interaction plus automatic data generation reduces the nominal 6 to 10 week time for manual generation and checking of data to a few days. The interactive graphics system consists of a series of satellite programs operated from a central NASTRAN Systems Monitor. Fuselage structural models including the outer shell and internal structure may be rapidly generated. All numbering systems are automatically assigned. Hard copy plots of the model labeled with GRID or elements ID's are also available. General purpose programs for displaying and editing NASTRAN data are included in the system. Utilization of the NASTRAN interactive graphics system has made possible the multiple finite element analysis of complex helicopter fuselage structures within design schedules
Staticity Theorem for Higher Dimensional Generalized Einstein-Maxwell System
We derive formulas for variations of mass, angular momentum and canonical
energy in Einstein (n-2)-gauge form field theory by means of the ADM formalism.
Considering the initial data for the manifold with an interior boundary which
has the topology of (n-2)-sphere we obtained the generalized first law of black
hole thermodynamics. Supposing that a black hole evevt horizon comprisesw a
bifurcation Killing horizon with a bifurcate surface we find that the solution
is static in the exterior world, when the Killing timelike vector field is
normal to the horizon and has vanishing electric or magnetic fields on static
slices.Comment: 10 pages, REVTEX, to published in Phys.Rev. D1
Cosmic Vortons and Particle Physics Constraints
We investigate the cosmological consequences of particle physics theories
that admit stable loops of superconducting cosmic string - {\it vortons}.
General symmetry breaking schemes are considered, in which strings are formed
at one energy scale and subsequently become superconducting in a secondary
phase transition at what may be a considerably lower energy scale. We estimate
the abundances of the ensuing vortons, and thereby derive constraints on the
relevant particle physics models from cosmological observations. These
constraints significantly restrict the category of admissible Grand Unified
theories, but are quite compatible with recently proposed effects whereby
superconducting strings may have been formed close to the electroweak phase
transition.Comment: 33 pages, 2 figures, RevTe
Covariant Vortex In Superconducting-Superfluid-Normal Fluid Mixtures with Stiff Equation of State
The integrals of motion for a cylindrically symmetric stationary vortex are
obtained in a covariant description of a mixture of interacting
superconductors, superfluids and normal fluids. The relevant integrated
stress-energy coefficients for the vortex with respect to a vortex-free
reference state are calculated in the approximation of a ``stiff'', i.e. least
compressible, relativistic equation of state for the fluid mixture. As an
illustration of the foregoing general results, we discuss their application to
some of the well known examples of ``real'' superfluid and superconducting
systems that are contained as special cases. These include Landau's two-fluid
model, uncharged binary superfluid mixtures, rotating conventional
superconductors and the superfluid neutron-proton-electron plasma in the outer
core of neutron stars.Comment: 14 pages, uses RevTeX and amssymb, submitte
Introductory workshops on remote sensing as related to geological problems in Georgia
There are no author-identified significant results in this report
Quantum integrability of quadratic Killing tensors
Quantum integrability of classical integrable systems given by quadratic
Killing tensors on curved configuration spaces is investigated. It is proven
that, using a "minimal" quantization scheme, quantum integrability is insured
for a large class of classic examples.Comment: LaTeX 2e, no figure, 35 p., references added, minor modifications. To
appear in the J. Math. Phy
Geometry of Deformations of Relativistic Membranes
A kinematical description of infinitesimal deformations of the worldsheet
spanned in spacetime by a relativistic membrane is presented. This provides a
framework for obtaining both the classical equations of motion and the
equations describing infinitesimal deformations about solutions of these
equations when the action describing the dynamics of this membrane is
constructed using {\it any} local geometrical worldsheet scalars. As examples,
we consider a Nambu membrane, and an action quadratic in the extrinsic
curvature of the worldsheet.Comment: 20 pages, Plain Tex, sign errors corrected, many new references
added. To appear in Physical Review
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