13,997 research outputs found
Experimental creep data for a built-up aluminum/titanium structure subjected to heating and loading
Experimental creep, temperature, and strain data resulting from a laboratory experiment on a built-up aluminum/titanium structure are presented. The structure and the experiment are described in detail. A heating and loading experiment lasting approximately six hours is conducted on a test structure. Considerable creep strain resulted from compressive stresses in the heated skin. Large residual stresses were found after the experiment was completed. The residual stresses in the substructure frames were large enough to preclude further cycles of creep experiments with this built-up structure because of concern that the frame webs would buckle
WHAT ODD EVEN EFFECTS MEAN IN LOW ENERGY FISSION ?
Odd even effects in fragment quantities from 233U(nth, f), 235U(nth, f) and 239Pu(nth, f) are, explained in terms of a statistical pair breaking mechanism during the descent from saddle to scission point. The probability that no pair will be broken is of the order of 1 per 1000. For 233U(nth, f) and 235U(nth,f), the average number of broken pair are 3.5 and 4., respectively, and the variances of the corresponding distributions are 1.4 and 1.3. The probability for one broken pair to be of protons (neutrons) is proportional to the numbers of proton (neutron) pairs in the system
Breaking a secure communication scheme based on the phase synchronization of chaotic systems
A security analysis of a recently proposed secure communication scheme based
on the phase synchronization of chaotic systems is presented. It is shown that
the system parameters directly determine the ciphertext waveform, hence it can
be readily broken by parameter estimation of the ciphertext signal.Comment: 4 pages, 6 figure
Long-range correlations and trends in Colombian seismic time series
We study long-range correlations and trends in time series extracted from the
data of seismic events occurred from 1973 to 2011 in a rectangular region that
contains mainly all the continental part of Colombia. The long-range
correlations are detected by the calculation of the Hurst exponents for the
time series of interevent intervals, separation distances, depth differences
and magnitude differences. By using a modification of the classical
method that has been developed to detect short-range correlations in time
series, we find the existence of persistence for all the time series considered
except for magnitude differences. We find also, by using the until the
third order, that the studied time series are not influenced by trends.
Additionally, an analysis of the Hurst exponent as a function of the number of
events in the time and the maximum window size is presented.Comment: 21 pages, 6 figures, 2 figures added, types corrected, accepted to be
published in Physica
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