736 research outputs found
Multiscale characterizations of surface anisotropies
Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a EDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies
Sudden vanishing and reappearance of nonclassical effects: General occurrence of finite-time decays and periodic vanishings of nonclassicality and entanglement witnesses
Analyses of phenomena exhibiting finite-time decay of quantum entanglement
have recently attracted considerable attention. Such decay is often referred to
as sudden vanishing (or sudden death) of entanglement, which can be followed by
its sudden reappearance (or sudden rebirth). We analyze various finite-time
decays (for dissipative systems) and analogous periodic vanishings (for unitary
systems) of nonclassical correlations as described by violations of classical
inequalities and the corresponding nonclassicality witnesses (or quantumness
witnesses), which are not necessarily entanglement witnesses. We show that
these sudden vanishings are universal phenomena and can be observed: (i) not
only for two- or multi-mode but also for single-mode nonclassical fields, (ii)
not solely for dissipative systems, and (iii) at evolution times which are
usually different from those of sudden vanishings and reappearances of quantum
entanglement.Comment: 10 pages, 3 figure
Fatigue behavior of hybrid continuous-discontinuous fiber-reinforced sheet molding compound composites under application-related loading conditions
Hybrid continuous-discontinuous sheet molding compound (SMC) composites are considered suitable candidates for structural automotive applications, due to their high mass-specific mechanical properties combined with high geometrical flexibility and low costs. Since structural automotive parts are subject to repeated loading, profound knowledge of their fatigue behavior is required. This paper presents an experimental study on the bending fatigue behavior of hybrid SMC with discontinuous glass fibers in the core and unidirectional continuous carbon fibers in the face layers. Effects of hybridization on the S-N behavior and stiffness degradation have been analyzed in constant amplitude fatigue tests under 3-point bending load at different temperatures and frequencies. Microscopic investigations on polished specimen edges were used to study the damage behavior. The ultimate flexural strength at quasi-static (UFS) and fatigue strain rate (UFS) of the hybrid composite was 54 % and 59 % higher than that of discontinuous SMC, respectively. In contrast, the flexural fatigue strength at 2.6⋅10S cycles increased by 258 %. The relative stiffness degradation of the hybrid composites was smaller during most of their fatigue lives due to the continuous carbon fiber reinforcement. The carbon fiber ply on the compression loaded side was the first ply to fail. Fatigue stress significantly decreased at 80 °C due to early kinking of the continuous carbon fiber-reinforced ply on the compression loaded side. Variation of frequency had no significant effect on the fatigue behavior of both discontinuous and continuous-discontinuous SMC
A lens-coupled scintillation counter in cryogenic environment
In this work we present an elegant solution for a scintillation counter to be
integrated into a cryogenic system. Its distinguishing feature is the absence
of a continuous light guide coupling the scintillation and the photodetector
parts, operating at cryogenic and room temperatures respectively. The prototype
detector consists of a plastic scintillator with glued-in wavelength-shifting
fiber located inside a cryostat, a Geiger-mode Avalanche Photodiode (G-APD)
outside the cryostat, and a lens system guiding the scintillation light
re-emitted by the fiber to the G-APD through optical windows in the cryostat
shields. With a 0.8mm diameter multiclad fiber and a 1mm active area G-APD the
coupling efficiency of the "lens light guide" is about 50%. A reliable
performance of the detector down to 3K is demonstrated.Comment: 14 pages, 11 figure
Magnetic Breakdown in the electron-doped cuprate superconductor NdCeCuO: the reconstructed Fermi surface survives in the strongly overdoped regime
We report on semiclassical angle-dependent magnetoresistance oscillations
(AMRO) and the Shubnikov-de Haas effect in the electron-overdoped cuprate
superconductor NdCeCuO. Our data provide convincing evidence
for magnetic breakdown in the system. This shows that a reconstructed
multiply-connected Fermi surface persists, at least at strong magnetic fields,
up to the highest doping level of the superconducting regime. Our results
suggest an intimate relation between translational symmetry breaking and the
superconducting pairing in the electron-doped cuprate superconductors.Comment: 5 pages, 4 figures, submitted to PR
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