6,781 research outputs found
Task Specific Uncertainty in Coordinate Measurement
Task specific uncertainty is the measurement uncertainty associated with the measurement of a specific feature using a specific measurement plan. This paper surveys techniques developed to model and estimate task specific uncertainty for coordinate measuring systems, primarily coordinate measuring machines using contacting probes. Sources of uncertainty are also reviewed
Part Form Errors Predicted from Machine Tool Performance Measurements
Machine tool performance testing, as defined by IS0 230 and ANSI B5.54 has been successfully used to maintain and improve the accuracy and repeatability of production-level machine tools. In this study, a controlled series of experiments have been used to test the efficacy of these performance tests in the prediction of part form errors. Results are shown for flatness, squareness, position, and profile tolerances. The experimental results suggest that standard machine tool performance tests can also be used to predict the “best-case” tolerances that can be achieved for particular part features
On the Gerasimov-Drell-Hearn sum rule for the deuteron
The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit
integration up to 550 MeV including contributions from the photodisintegration
channel and from coherent and incoherent single pion production as well. The
photodisintegration channel converges fast enough in this energy range and
gives a large negative contribution, essentially from the resonant
state near threshold. Its absolute value is about the same size as the sum of
proton and neutron GDH values. It is only partially cancelled by the single
pion production contribution. But the incoherent channel has not reached
convergence at 550 MeV.Comment: 6 pages latex including 3 postscript figures, talk at the 15th Int.
Conf. on Few-Body Problems in Physics, Groningen, Netherlands, 22-26 July
1997. To be published in Nucl. Phys.
Effect of pressure cycling on Iron: Signatures of an electronic instability and unconventional superconductivity
High pressure electrical resistivity and x-ray diffraction experiments have
been performed on Fe single crystals. The crystallographic investigation
provides direct evidence that in the martensitic
transition at 14 GPa the become the directions. During a pressure cycle, resistivity shows a
broad hysteresis of 6.5 GPa, whereas superconductivity, observed between 13 and
31 GPa, remains unaffected. Upon increasing pressure an electronic instability,
probably a quantum critical point, is observed at around 19 GPa and, close to
this pressure, the superconducting and the isothermal resistivity
(K) attain maximum values. In the superconducting pressure domain,
the exponent of the temperature power law of resistivity and its
prefactor, which mimics , indicate that ferromagnetic fluctuations may
provide the glue for the Cooper pairs, yielding unconventional
superconductivity
Quasifree pion photoproduction on the deuteron in the region
Photo production of pions on the deuteron is studied in the spectator nucleon
model. The Born terms of the elementary production amplitude are determined in
pseudovector N coupling and supplied with a form factor. The
resonance is considered both in the and the channel. The parameters of
the resonance and the cutoff of the form factors are fixed on the
leading photoproduction multipoles. Results for total and differential cross
sections are compared with experimental data. Particular attention is paid to
the role of Pauli correlations of the final state nucleons in the quasifree
case. The results are compared with those for pion photoproduction on the
nucleon.Comment: 17 pages LateX2e including 5 postscript figure
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