3,501 research outputs found
Gyro spring augmentation system
Spring-loaded piston with provision for hydraulic control of spring action varies the stiffness of hydraulic control systems
Nonradiative limitations to plasmon propagation in chains of metallic nanoparticles
We investigate the collective plasmonic modes in a chain of metallic
nanoparticles that are coupled by near-field interactions. The size- and
momentum-dependent nonradiative Landau damping and radiative decay rates are
calculated analytically within an open quantum system approach. These decay
rates determine the excitation propagation along the chain. In particular, the
behavior of the radiative decay rate as a function of the plasmon wavelength
leads to a transition from an exponential decay of the collective excitation
for short distances to an algebraic decay for large distances. Importantly, we
show that the exponential decay is of a purely nonradiative origin. Our
transparent model enables us to provide analytical expressions for the
polarization-dependent plasmon excitation profile along the chain and for the
associated propagation length. Our theoretical analysis constitutes an
important step in the quest for the optimal conditions for plasmonic
propagation in nanoparticle chains.Comment: 14 pages, 6 figures; v2: published versio
Decay of dark and bright plasmonic modes in a metallic nanoparticle dimer
We develop a general quantum theory of the coupled plasmonic modes resulting
from the near-field interaction between localized surface plasmons in a
heterogeneous metallic nanoparticle dimer. In particular, we provide analytical
expressions for the frequencies and decay rates of the bright and dark
plasmonic modes. We show that, for sufficiently small nanoparticles, the main
decay channel for the dark plasmonic mode, which is weakly coupled to light
and, hence, immune to radiation damping, is of nonradiative origin and
corresponds to Landau damping, i.e., decay into electron-hole pairs.Comment: 9 pages, 3 figures; published versio
Effect of Extrusion Parameters on Properties of Powder Coatings Determined by Infrared Spectroscopy
In polymer extrusion, compounding is a continuous mixing process that is also used to produce highly reactive powder coatings. A premixed batch of powder coating is added to the feeding section and extruded, preferably by a co-rotating twin-screw extruder. One essential parameter in the processing of highly reactive materials is the melt temperature: If it is too high, pre-reactions occur during the extrusion process, which may cause high rejection rates. We studied the melt temperature of an epoxy/carboxyl-based powder coating using a retractable thermocouple at 3 different axial positions along the barrel of a ZSK34 co-rotating twin-screw extruder. The influence of different processing conditions on the reactivity of a highly reactive powder coating was examined by infrared spectroscopy and differential scanning calorimetry. Furthermore, the specific energy input and the color change in the finished powder coating at different processing points were investigated. Multivariate data analysis was used to correlate mid-infrared spectra, melt temperatures, specific energy inputs, enthalpies of reaction and changes in color
Local equilibrium in heavy-ion collisions: microscopic analysis of a central cell versus infinite matter
REVTEX, 27 pages incl. 10 figures and 3 tables; Phys. Rev. C (in press) Journal-ref: Phys.Rev. C62 (2000) 064906. We study the local equilibrium in the central V = 125 fm3 cell in heavy-ion collisions at energies from 10.7 A GeV (AGS) to 160 A GeV (SPS) calculated in the microscopic transport model. In the present paper the hadron yields and energy spectra in the cell are compared with those of infinite nuclear matter, as calculated within the same model. The agreement between the spectra in the two systems is established for times t >= 10 fm/c in the central cell. The cell results do not deviate noticeably from the infinite matter calculations with rising incident energy, in contrast to the apparent discrepancy with predictions of the statistical model (SM) of an ideal hadron gas. The entropy of this state is found to be very close to the maximum entropy, while hadron abundances and energy spectra differ significantly from those of the SM
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STONE 6: Artificial Sedimentary Meteorites in Space
The STONE 6 experiment demonstrated the survivability of carbonaceous and microfossiliferous martian analogue sediments during atmospheric re-entry. Doped endoliths died but their carbonised cells remained
Are we close to the QGP? - Hadrochemical vs. microscopic analysis of particle production in ultrarelativistic heavy ion collisions
Ratios of hadronic abundances are analyzed for pp and nucleus-nucleus collisions at sqrt(s)=20 GeV using the microscopic transport model UrQMD. Secondary interactions significantly change the primordial hadronic cocktail of the system. A comparison to data shows a strong dependence on rapidity. Without assuming thermal and chemical equilibrium, predicted hadron yields and ratios agree with many of the data, the few observed discrepancies are discussed
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