1,198 research outputs found
Rolling-element fatigue life with traction fluids and automatic transmission fluid in a high-speed rolling-contact rig
Rolling-element fatigue tests were run in standard and high-speed rolling-contact rigs at bar speeds from 5000 to 50,000 rpm to determine the effects of speed and lubricant film parameter on rolling-element fatigue life. AISI 52100 test bars were tested at a maximum Hertz stress of 4.83 GPa (700,000 psi) with three traction fluids and an automatic transmission fluid. Rolling-element fatigue life increased with speed, with the greatest increases occurring from 10,000 to 50,000 rpm. The life data tended to follow published life-versus-lubricant-film-parameter data up to a film parameter of approximately 3
The Hagedorn Temperature and Partition Thermodynamics
We review the resonance gas formalism of hadron thermodynamics and recall
that an exponential increase of the resonance spectrum leads to a limiting
temperature of hadronic matter. We then show that the number p(n) of ordered
partitions of an integer n grows exponentially with n and satisfies the integer
counterpart of the statistical bootstrap equation. Considering the set of all
partitions as a Gibbs ensemble provides a partition thermodynamics which is
also governed by a limiting temperature, determined by the combinatorial
structure of the problem. Further associating intrinsic quantum numbers to
integers results in a phase diagram equivalent to that found in QCD for
hadronic matter as function of temperature and baryochemical potential.Comment: Dedicated to Rolf Hagedorn, 1919-2003. 11 pages, 3 figures. Final
version accepted for publication in the European Physical Journal
Spinor Algebras
We consider supersymmetry algebras in space-times with arbitrary signature
and minimal number of spinor generators. The interrelation between super
Poincar\'e and super conformal algebras is elucidated. Minimal super conformal
algebras are seen to have as bosonic part a classical semimisimple algebra
naturally associated to the spin group. This algebra, the Spin-algebra,
depends both on the dimension and on the signature of space time. We also
consider maximal super conformal algebras, which are classified by the
orthosymplectic algebras.Comment: References added, misprints corrected. Version to appear in the
Journal of Geometry and Physic
Orbifold resolutions with general profile
A very general class of resolved versions of the C/Z_N, T^2/Z_N and S^1/Z_2
orbifolds is considered and the free theory of 6D chiral fermions studied on
it. As the orbifold limit is taken, localized 4D chiral massless fermions are
seen to arise at the fixed points. Their number, location and chirality is
found to be independent on the detailed profile of the resolving space and to
agree with the result of hep-th/0409229, in which a particular resolution was
employed. As a consistency check of the resolution procedure, the massive
equation is numerically studied. In particular, for S^1/Z_2, the "resolved"
mass--spectrum and wave functions in the internal space are seen to correctly
reproduce the usual orbifold ones, as the orbifold limit is taken.Comment: 28 pages, 3 figures, typos corrected, references adde
Numerical Investigation of Monopole Chains
We present numerical results for chains of SU(2) BPS monopoles constructed
from Nahm data. The long chain limit reveals an asymmetric behavior transverse
to the periodic direction, with the asymmetry becoming more pronounced at
shorter separations. This analysis is motivated by a search for semiclassical
finite temperature instantons in the 3D SU(2) Georgi-Glashow model, but it
appears that in the periodic limit the instanton chains either have
logarithmically divergent action or wash themselves out.Comment: 14 pages, 6 figures; v2 minor changes, published versio
Free tensor multiplets and strings in spontaneously broken six-dimensional (2,0) theory
We first review the representations of the six-dimensional (2,0) superalgebra
on a free tensor multiplet and on a free string. We then construct a
supersymmetric Lagrangian describing a free tensor multiplet. (It also includes
a decoupled anti self-dual part of the three-form field strength.) This field
theory is then rewritten in variables appropriate for analyzing a situation
where the R-symmetry is spontaneously broken by the vacuum expectation values
of the scalar moduli fields. Finally, we construct a supersymmetric and
kappa-symmetric action for a free string.Comment: 15 pages, LaTe
Democratic Supersymmetry
We present generalisations of N-extended supersymmetry algebras in four
dimensions, using Lorentz covariance and invariance under permutation of the N
supercharges as selection criteria.Comment: 26 pages, latex fil
Stringy Derivation of Nahm Construction of Monopoles
We derive the Nahm construction of monopoles from exact tachyon condensation
on unstable D-branes. The Dirac operator used in the Nahm construction is
identified with the tachyon profile in our D-brane approach, and we provide
physical interpretation of the procedures Nahm gave. Crucial is the
introduction of infinite number of brane-antibranes from which arbitrary
D-brane can be constrcuted, exhibitting a unified view of various D-branes. We
explicitly show the equivalence of the D3-brane boundary state with the
monopole profile and the D1-brane boundary state with the Nahm data as
transverse scalars.Comment: 18 pages, 4 eps figures, JHEP style, comments about low energy limits
added, references adde
A new approximation scheme in quantum mechanics
An approximation method which combines the perturbation theory with the
variational calculation is constructed for quantum mechanical problems. Using
the anharmonic oscillator and the He atom as examples, we show that the present
method provides an efficient scheme in estimating both the ground and the
excited states. We also discuss the limitations of the present method.Comment: 14pages, to be published in Eur. J. Phy
- …