22,861 research outputs found
Determination of airplane model structure from flight data by using modified stepwise regression
The linear and stepwise regressions are briefly introduced, then the problem of determining airplane model structure is addressed. The MSR was constructed to force a linear model for the aerodynamic coefficient first, then add significant nonlinear terms and delete nonsignificant terms from the model. In addition to the statistical criteria in the stepwise regression, the prediction sum of squares (PRESS) criterion and the analysis of residuals were examined for the selection of an adequate model. The procedure is used in examples with simulated and real flight data. It is shown that the MSR performs better than the ordinary stepwise regression and that the technique can also be applied to the large amplitude maneuvers
Manifestations of a spatial variation of fundamental constants on atomic clocks, Oklo, meteorites, and cosmological phenomena
The remarkable detection of a spatial variation in the fine-structure
constant, alpha, from quasar absorption systems must be independently confirmed
by complementary searches. In this letter, we discuss how terrestrial
measurements of time-variation of the fundamental constants in the laboratory,
meteorite data, and analysis of the Oklo nuclear reactor can be used to
corroborate the spatial variation seen by astronomers. Furthermore, we show
that spatial variation of the fundamental constants may be observable as
spatial anisotropy in the cosmic microwave background, the accelerated
expansion (dark energy), and large-scale structure of the Universe.Comment: 4 page
The biochemical, physiological, and metabolic effects of Apollo nominal mission and contingency diets on human subjects while on a simulated Apollo mission Final report, Feb. - Jun. 1966
Biochemical, physiological, and metabolic effects of simulated Apollo mission with space diet on human
Limits on cosmological variation of quark masses and strong interaction
We discuss limits on variation of . The results are
obtained by studying -interaction during Big Bang, Oklo natural
nuclear reactor data and limits on variation of the proton -factor from
quasar absorpion spectra.Comment: 5 pages, RevTe
Big bang nucleosynthesis as a probe of fundamental "constants"
Big Bang nucleosynthesis (BBN) is the earliest sensitive probe of the values
of many fundamental particle physics parameters. We have found the leading
linear dependences of primordial abundances on all relevant parameters of the
standard BBN code, including binding energies and nuclear reaction rates. This
enables us to set limits on possible variations of fundamental parameters. We
find that 7Li is expected to be significantly more sensitive than other species
to many fundamental parameters, a result which also holds for variations of
coupling strengths in grand unified (GUT) models. Our work also indicates which
areas of nuclear theory need further development if the values of ``constants''
are to be more accurately probed.Comment: Refereed article to be published in Nuclear Physics in Astrophysics
III Proceedings, J. Phys. G. Special Issue. Based on work in collaboration
with C. Wetterich (Heidelberg). 6 page
Preliminary results of penetrator field test program, Tonopah, Nevada, 16-28 April 1979
Subscale (0.63 scale) penetrators impacted various sizes of volcanic rocks resting on and within compacted plays sediments. All penetrators were identical in size, shape, weight, and impact velocity. Although minor variations in impact angle were documented, the final orientation of the buried penetrators was primarily a consequence of the size, shape, and depth of the rocks encountered during impact. In situ measurements of impacted penetrators revealed that surface and buried layers of rocks having diameters up to 3 times the penetrator diameter caused only small ( 10 deg) angles of deflection. Only large single rocks greater than 10 times the penetrator diameter caused deflections appreciably greater than 10 deg. The large deflection angles followed by the penetrator were strongly influenced by fracture planes that developed in the rock as it broke apart. No catastrophic failure of the penetrator occurred during these tests. A cross section of the path of each penetrator through the ground is shown together with details on orientation before, during, and after the tests. Comparisons are made with results of previous subscale penetrator tests, and conclusions are drawn with respect to full-scale Mars penetrator performance
Field Measurements of Penetrator Seismic Coupling in Sediments and Volcanic Rocks
Field experiments were conducted to determine how well a seismometer installed using a penetrator would be coupled to the ground. A dry-lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were at various distances to generate seismic signals. These signals were detected by the penetrator-mounted geophone assembly and by a reference geophone assembly buried or anchored to surface rock and 1-m from the penetrator. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence, and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology
Fractional Exclusion Statistics for the Multicomponent Sutherland Model
We show by microscopic calculation that thermodynamics of the multicomponent
Sutherland model is equivalent to that of a free particle system with
fractional exclusion statistics at all temperatures. The parameters for
exclusion statistics are given by the strength of the repulsive interaction,
and have both intra- and inter-species components. We also show that low
temperature properties of the system are described in terms of free fractional
particles without the statistical parameters for different species. The
effective exclusion statistics for intra-species at low temperatures depend on
polarization of the system.Comment: 13 pages, using RevTex, 5 figures on reques
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