2,559 research outputs found
Graph transformation for verification and concurrency
The talk will begin with a brief introduction to Rewriting Logic and use of the Maude language. A case study based on modeling security aspects a remote service toolkit will be used to illustrate the approach to formal modeling and analysis in more detail
Static and Dynamic Strength Properties of a Fiber-Reinforced Compacted Cohesive Soil
Soil reinforcement with randomly oriented, individual synthetic fibers has been applied to laboratory specimens of a compacted cohesive soil. Fiber contents of up to 1.0% by soil dry weight were mixed with the soil. Data from unconfined compression (static) testing and resilient modulus (dynamic) testing have been presented. Experimental work showed that the fibers increased the soil unconfined compressive strength, ductility, toughness, static and dynamic energy absorption capacities, the resilient strain and the number of cycles to failure. The soil resilient modulus and the permanent strain both decreased with the increase in fiber content
Test of the isotropy of the speed of light using a continuously rotating optical resonator
We report on a test of Lorentz invariance performed by comparing the
resonance frequencies of one stationary optical resonator and one continuously
rotating on a precision air bearing turntable. Special attention is paid to the
control of rotation induced systematic effects. Within the photon sector of the
Standard Model Extension, we obtain improved limits on combinations of 8
parameters at a level of a few parts in . For the previously least
well known parameter we find . Within the Robertson-Mansouri-Sexl test theory, our measurement
restricts the isotropy violation parameter to
, corresponding to an eightfold improvement with
respect to previous non-rotating measurements.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let
New CP-violation and preferred-frame tests with polarized electrons
We used a torsion pendulum containing polarized
electrons to search for CP-violating interactions between the pendulum's
electrons and unpolarized matter in the laboratory's surroundings or the sun,
and to test for preferred-frame effects that would precess the electrons about
a direction fixed in inertial space. We find and for AU. Our preferred-frame constraints, interpreted in
the Kosteleck\'y framework, set an upper limit on the parameter eV that should be compared to the benchmark
value eV.Comment: 4 figures, accepted for publication in Physical Review Letter
The Riemann-Cartan space in the O-theory
Nonrelativistic equation of particle with a spin for the Lagrangian on a
nonassociative algebra is obtained. It is shown that in this model arises
Riemann-Cartan space. In the case of central symmetry in addition to the
pseudo-curvature appears torsion as pseudovector that interacts with the spin
of the particle. An estimation of the influence of torsion on the strength of
gravitational attraction in the central gravitational field is given.Comment: 12 page
Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale
We conducted three torsion-balance experiments to test the gravitational
inverse-square law at separations between 9.53 mm and 55 micrometers, probing
distances less than the dark-energy length scale m. We find with 95% confidence
that the inverse-square law holds () down to a length scale
m and that an extra dimension must have a size m.Comment: 4 pages, 6 figure
Spin-Dependent Macroscopic Forces from New Particle Exchange
Long-range forces between macroscopic objects are mediated by light particles
that interact with the electrons or nucleons, and include spin-dependent static
components as well as spin- and velocity-dependent components. We parametrize
the long-range potential between two fermions assuming rotational invariance,
and find 16 different components. Applying this result to electrically neutral
objects, we show that the macroscopic potential depends on 72 measurable
parameters. We then derive the potential induced by the exchange of a new gauge
boson or spinless particle, and compare the limits set by measurements of
macroscopic forces to the astrophysical limits on the couplings of these
particles.Comment: 37 page
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