8,707 research outputs found
Using modular decomposition technique to solve the maximum clique problem
In this article we use the modular decomposition technique for exact solving
the weighted maximum clique problem. Our algorithm takes the modular
decomposition tree from the paper of Tedder et. al. and finds solution
recursively. Also, we propose algorithms to construct graphs with modules. We
show some interesting results, comparing our solution with Ostergard's
algorithm on DIMACS benchmarks and on generated graph
Recent Load Calibrations Experience with the YF-12 Airplane
The use of calibrated strain gages to measure wing loads on the YF-12A airplane is discussed as well as structural configurations relative to the thermal environment and resulting thermal stresses. A thermal calibration of the YF-12A is described to illustrate how contaminating thermal effects can be removed from loads equations. The relationship between ground load calibrations and flight measurements is examined for possible errors, and an analytical approach to accommodate such errors is presented
A study of the effect of radical load distributions on calibrated strain gage load equations
For several decades, calibrated strain gages have been used to measure loads on airplanes. The accuracy of the equations used to relate the strain gage measurements to the applied loads has been based primarily on the results of the load calibration. An approach is presented for studying the effect of widely varying load distributions on strain gage load equations. The computational procedure provides a link between the load calibration and the load to be measured in flight. A matrix approach to equation selection is presented, which is based on equation standard error, load distribution, and influence coefficient plots of the strain gage equations, and is applied to a complex, delta-wing structure
Induced subarrays of Latin squares without repeated symbols
We show that for any Latin square L of order 2m, we can partition the rows and columns of L into pairs so that at most (m+3)/2 of the 2x2 subarrays induced contain a repeated symbol. We conjecture that any Latin square of order 2m (where m ≥ 2, with exactly five transposition class exceptions of order 6) has such a partition so that every 2x2 subarray induced contains no repeated symbol. We verify this conjecture by computer when m ≤ 4
Experimental Observation of a Fundamental Length Scale of Waves in Random Media
Waves propagating through a weakly scattering random medium show a pronounced
branching of the flow accompanied by the formation of freak waves, i.e.,
extremely intense waves. Theory predicts that this strong fluctuation regime is
accompanied by its own fundamental length scale of transport in random media,
parametrically different from the mean free path or the localization length. We
show numerically how the scintillation index can be used to assess the scaling
behavior of the branching length. We report the experimental observation of
this scaling using microwave transport experiments in quasi-two-dimensional
resonators with randomly distributed weak scatterers. Remarkably, the scaling
range extends much further than expected from random caustics statistics.Comment: 5 pages, 5 figure
Correlations of electromagnetic fields in chaotic cavities
We consider the fluctuations of electromagnetic fields in chaotic microwave
cavities. We calculate the transversal and longitudinal correlation function
based on a random wave assumption and compare the predictions with measurements
on two- and three-dimensional microwave cavities.Comment: Europhys style, 8 pages, 3 figures (included
Current and vorticity auto correlation functions in open microwave billiards
Using the equivalence between the quantum-mechanical probability density in a
quantum billiard and the Poynting vector in the corresponding microwave system,
current distributions were studied in a quantum dot like cavity, as well as in
a Robnik billiard with lambda=0.4, and an introduced ferrite cylinder. Spatial
auto correlation functions for currents and vorticity were studied and compared
with predictions from the random-superposition-of-plane-waves hypothesis. In
addition different types of vortex neighbour spacing distributions were
determined and compared with theory.Comment: PTP-LaTeX, 10 pages with 6 figures submitted to Progress of
Theoretical Physics Supplemen
Algebraic fidelity decay for local perturbations
From a reflection measurement in a rectangular microwave billiard with
randomly distributed scatterers the scattering and the ordinary fidelity was
studied. The position of one of the scatterers is the perturbation parameter.
Such perturbations can be considered as {\em local} since wave functions are
influenced only locally, in contrast to, e. g., the situation where the
fidelity decay is caused by the shift of one billiard wall. Using the
random-plane-wave conjecture, an analytic expression for the fidelity decay due
to the shift of one scatterer has been obtained, yielding an algebraic
decay for long times. A perfect agreement between experiment and theory has
been found, including a predicted scaling behavior concerning the dependence of
the fidelity decay on the shift distance. The only free parameter has been
determined independently from the variance of the level velocities.Comment: 4 pages, 5 figure
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