3,594 research outputs found
Fatigue loading history reconstruction based on the rain-flow technique
Methods are considered for reducing a non-random fatigue loading history to a concise description and then for reconstructing a time history similar to the original. In particular, three methods of reconstruction based on a rain-flow cycle counting matrix are presented. A rain-flow matrix consists of the numbers of cycles at various peak and valley combinations. Two methods are based on a two dimensional rain-flow matrix, and the third on a three dimensional rain-flow matrix. Histories reconstructed by any of these methods produce a rain-flow matrix identical to that of the original history, and as a result the resulting time history is expected to produce a fatigue life similar to that for the original. The procedures described allow lengthy loading histories to be stored in compact form
Commonalities in the psychological factors associated with problem gambling and internet dependence
Fatigue life estimates for helicopter loading spectra
Helicopter loading histories applied to notch metal samples are used as examples, and their fatigue lives are calculated by using a simplified version of the local strain approach. This simplified method has the advantage that it requires knowing the loading history in only the reduced form of ranges and means and number of cycles from the rain-flow cycle counting method. The calculated lives compare favorably with test data
The Vortex Phase Qubit: Generating Arbitrary, Counter-Rotating, Coherent Superpositions in Bose-Einstein Condensates via Optical Angular Momentum Beams
We propose a scheme for generation of arbitrary coherent superposition of
vortex states in Bose-Einstein condensates (BEC) using the orbital angular
momentum (OAM) states of light. We devise a scheme to generate coherent
superpositions of two counter-rotating OAM states of light using known
experimental techniques. We show that a specially designed Raman scheme allows
transfer of the optical vortex superposition state onto an initially
non-rotating BEC. This creates an arbitrary and coherent superposition of a
vortex and anti-vortex pair in the BEC. The ideas presented here could be
extended to generate entangled vortex states, design memories for the OAM
states of light, and perform other quantum information tasks. Applications to
inertial sensing are also discussed.Comment: 4 pages, 4 figures, Revtex4, to be submitted to Phys. Rev. Let
Local and Global Distinguishability in Quantum Interferometry
A statistical distinguishability based on relative entropy characterises the
fitness of quantum states for phase estimation. This criterion is employed in
the context of a Mach-Zehnder interferometer and used to interpolate between
two regimes, of local and global phase distinguishability. The scaling of
distinguishability in these regimes with photon number is explored for various
quantum states. It emerges that local distinguishability is dependent on a
discrepancy between quantum and classical rotational energy. Our analysis
demonstrates that the Heisenberg limit is the true upper limit for local phase
sensitivity. Only the `NOON' states share this bound, but other states exhibit
a better trade-off when comparing local and global phase regimes.Comment: 4 pages, in submission, minor revision
Quantum Clock Synchronization Based on Shared Prior Entanglement
We demonstrate that two spatially separated parties (Alice and Bob) can
utilize shared prior quantum entanglement, and classical communications, to
establish a synchronized pair of atomic clocks. In contrast to classical
synchronization schemes, the accuracy of our protocol is independent of Alice
or Bob's knowledge of their relative locations or of the properties of the
intervening medium.Comment: 4 page
Measurement of Photon Statistics with Live Photoreceptor Cells
We analyzed the electrophysiological response of an isolated rod
photoreceptor of Xenopus laevis under stimulation by coherent and
pseudo-thermal light sources. Using the suction electrode technique for single
cell recordings and a fiber optics setup for light delivery allowed
measurements of the major statistical characteristics of the rod response. The
results indicate differences in average responses of rod cells to coherent and
pseudo-thermal light of the same intensity and also differences in
signal-to-noise ratios and second order intensity correlation functions. These
findings should be relevant for interdisciplinary studies seeking applications
of quantum optics in biology.Comment: 6 pages, 7 figure
Adhesion Improvement of Thermoplastics-Based Composites by Atmospheric Plasma and UV Treatments
The present work is concerned with adhesive bonding of thermoplastic composites used in general aerospace applications, including polyphenylene sulfide (PPS), polyetherimide (PEI) and polyetheretherketone (PEEK) carbon fibre composites. Three different surface treatments have been applied to the PEEK, PPS and PEI-based composites in order to enhance the adhesion: atmospheric plasma, ultraviolet radiation (UV) and isopropanol wiping as a control. Water contact angles and free surface energies were measured following the standard experimental procedure based on the employment of three different liquid droplets. Infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) were subsequently performed to characterize the surface chemistry of the samples after treatment. The single lap joints were manufactured and bonded by an Aerospace grade epoxy-based film adhesive originally developed for use on metals but with the ability to bond treated thermoplastics to good strength (supplied by Henkel Ireland). Quasi-static (QS) tests were conducted. The lap shear strength was evaluated, and the failure mechanisms of the different joints were examined for the range of surface treatments considered. It was found that the performances of the PEEK and PPS joints were considerably improved by the plasma and UV treatments resulting in cohesive and delamination failures, while PEI was unaffected by the plasma and UV treatments and performed very well throughout
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