4,303 research outputs found
Determination of orbits of planetary artificial satellites and planetary gravitational fields
Orbit determination of planetary artificial satellites and planetary gravitational field
Higher compressive strengths and the Bauschinger effect in conformally passivated copper nanopillars
Our current understanding of size-dependent strength in nano- and microscale crystals is centered around the idea that the overall strength is determined by the stress required to propagate dislocation sources. The nature and type of these dislocation sources is the subject of extensive debate, however, one commonality amongst these theories is that the ability of the free surface to absorb dislocations is a necessary condition for transition to a source controlled regime. In this work we demonstrate that atomic layer deposition (ALD) of conformal 5–25 nm thick TiO_2/Al_(2)O_3 coatings onto electroplated single crystalline copper pillars with diameters ranging from 75 nm to 1 μm generally inhibits the ability of a dislocation to vanish at the free surface. Uniaxial compression tests reveal increased strength and hardening relative to uncoated pillars at equivalent diameters, as well as a notable recovery of plastic strain during unloading, i.e. the Bauschinger effect. Unlike previous reports, these coated pillars retained the stochastic signature in their stress–strain curves. We explain these observations within the framework of a size-dependent strength theory based on a single arm source model, dislocation theory, and microstructural analysis by transmission electron microscopy
Labelling, Deviance and Media
Labelling theory is a perspective that emerged as a distinctive approach to criminology during the 1960s, and was a major seedbed of the radical and critical perspectives that became prominent in the 1970s. It represented the highpoint of an epistemological shift within the social sciences away from positivism – which had dominated criminological enquiry since the late-1800s – and toward an altogether more relativistic stance on the categories and concepts of crime and control. It inspired a huge amount of work throughout the 1960s and 1970s, and still resonates powerfully today. This short chapter maps out some of the ways in which labelling, deviance, media and justice interact at the levels of definition and process. It presents an overview and analysis of key mediatised labelling processes, such as the highly influential concept of moral panics. It discusses how the interconnections between labelling, crime and criminal justice are changing in a context of technological development, cultural change and media proliferation. The conclusion offers an assessment and evaluation of labelling theory’s long-term impact on criminology
Structural Color 3D Printing By Shrinking Photonic Crystals
The rings, spots and stripes found on some butterflies, Pachyrhynchus
weevils, and many chameleons are notable examples of natural organisms
employing photonic crystals to produce colorful patterns. Despite advances in
nanotechnology, we still lack the ability to print arbitrary colors and shapes
in all three dimensions at this microscopic length scale. Commercial nanoscale
3D printers based on two-photon polymerization are incapable of patterning
photonic crystal structures with the requisite ~300 nm lattice constant to
achieve photonic stopbands/ bandgaps in the visible spectrum and generate
colors. Here, we introduce a means to produce 3D-printed photonic crystals with
a 5x reduction in lattice constants (periodicity as small as 280 nm), achieving
sub-100-nm features with a full range of colors. The reliability of this
process enables us to engineer the bandstructures of woodpile photonic crystals
that match experiments, showing that observed colors can be attributed to
either slow light modes or stopbands. With these lattice structures as 3D color
volumetric elements (voxels), we printed 3D microscopic scale objects,
including the first multi-color microscopic model of the Eiffel Tower measuring
only 39-microns tall with a color pixel size of 1.45 microns. The technology to
print 3D structures in color at the microscopic scale promises the direct
patterning and integration of spectrally selective devices, such as photonic
crystal-based color filters, onto free-form optical elements and curved
surfaces
Wind tunnel investigation of static longitudinal and lateral characteristics of a full scale mockup of a light single engine high wing airplane
The model was a full-scale mockup of a light single-engine high-wing monoplane. Tests were made over an angle-of-attack range of -4 deg to 24 deg and over a sideslip range of plus or minus 8 deg at thrust coefficients of 0, 0.14, and 0.30. Control effectiveness and hinge moments were taken on the aileron, elevator, and rudder for a full range of deflections. Downwash measurements at the tail were obtained for the range of thrust coefficient and flap deflection
A Multi-Wavelength Mass Analysis of RCS2 J232727.6-020437, a ~3x10M Galaxy Cluster at z=0.7
We present an initial study of the mass and evolutionary state of a massive
and distant cluster, RCS2 J232727.6-020437. This cluster, at z=0.6986, is the
richest cluster discovered in the RCS2 project. The mass measurements presented
in this paper are derived from all possible mass proxies: X-ray measurements,
weak-lensing shear, strong lensing, Sunyaev Zel'dovich effect decrement, the
velocity distribution of cluster member galaxies, and galaxy richness. While
each of these observables probe the mass of the cluster at a different radius,
they all indicate that RCS2 J232727.6-020437 is among the most massive clusters
at this redshift, with an estimated mass of M_200 ~3 x10^15 h^-1 Msun. In this
paper, we demonstrate that the various observables are all reasonably
consistent with each other to within their uncertainties. RCS2 J232727.6-020437
appears to be well relaxed -- with circular and concentric X-ray isophotes,
with a cool core, and no indication of significant substructure in extensive
galaxy velocity data.Comment: 19 pages, 15 figures, submitted to ApJ on March 5, 2015; in press.
Manuscript revised following the referee revie
- …