105,773 research outputs found
On the Measure in Simplicial Gravity
Functional measures for lattice quantum gravity should agree with their
continuum counterparts in the weak field, low momentum limit. After showing
that the standard simplicial measure satisfies the above requirement, we prove
that a class of recently proposed non-local measures for lattice gravity do not
satisfy such a criterion, already to lowest order in the weak field expansion.
We argue therefore that the latter cannot represent acceptable discrete
functional measures for simplicial geometries.Comment: LaTeX, 15 pages, 2 figure
Nonparametric Regression using the Concept of Minimum Energy
It has recently been shown that an unbinned distance-based statistic, the
energy, can be used to construct an extremely powerful nonparametric
multivariate two sample goodness-of-fit test. An extension to this method that
makes it possible to perform nonparametric regression using multiple
multivariate data sets is presented in this paper. The technique, which is
based on the concept of minimizing the energy of the system, permits
determination of parameters of interest without the need for parametric
expressions of the parent distributions of the data sets. The application and
performance of this new method is discussed in the context of some simple
example analyses.Comment: 10 pages, 4 figure
Non-destructive method for applying and removing instrumentation on helicopter rotor blades
A nondestructive method of applying and removing instrumentation on airfoils
Newtonian Potential in Quantum Regge Gravity
We show how the Newtonian potential between two heavy masses can be computed
in simplicial quantum gravity. On the lattice we compute correlations between
Wilson lines associated with the heavy particles and which are closed by the
lattice periodicity. We check that the continuum analog of this quantity
reproduces the Newtonian potential in the weak field expansion. In the smooth
anti-de Sitter-like phase, which is the only phase where a sensible lattice
continuum limit can be constructed in this model, we attempt to determine the
shape and mass dependence of the attractive potential close to the critical
point in . It is found that non-linear graviton interactions give rise to a
potential which is Yukawa-like, with a mass parameter that decreases towards
the critical point where the average curvature vanishes. In the vicinity of the
critical point we give an estimate for the effective Newton constant.Comment: (47 pages), CERN-TH.7314/9
The asymptotics of an amplitude for the 4-simplex
An expression for the oscillatory part of an asymptotic formula for the
relativistic spin network amplitude for a 4-simplex is given. The amplitude
depends on specified areas for each two-dimensional face in the 4-simplex. The
asymptotic formula has a contribution from each flat Euclidean metric on the
4-simplex which agrees with the given areas. The oscillatory part of each
contribution is determined by the Regge calculus Einstein action for that
geometry.Comment: 5 pages amstex, typos correcte
Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding
The process characteristics of the synergic cold metal transfer (CMT) process
have been examined for welding aluminium alloy. Utilising a simple backlighting
system and through the arc monitoring the droplet transfer modes were
identified. Whilst the modified short circuit mode was evident for the lower
parameter range, a two part transfer mode based upon a combination of spray and
short circuit transfer was observed for the mid to upper parameter range. The
technology was also explored as a cladding process for applying to ternary
alloyed (Al–Cu–Mg) aluminium plate. This alloy system is known to be susceptible
to solidification cracking when MIG welded using the binary Al-2319 (Al–Cu)
filler wire, this being due to the wide element freezing range of the weld
resulting from mixing with the base material. Utilising this filler, weld
dilution ratios for both CMT and pulsed welding were identified across the
examined parameter range. The CMT process exhibited greater control of dilution
that enabled deposition of a quasi-binary (Al–Cu) layer exhibiting a less crack
susceptible composition. Onto this layer conventional MIG welding could be
applied which could potentially eradicate cracking using a binary fi
Tracking radar studies of bird migration
The application of tracking radar for determining the flight paths of migratory birds is discussed. The effects produced by various meteorological parameters are described. Samples of radar scope presentations obtained during tracking studies are presented. The characteristics of the radars and their limitations are examined
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