2,158 research outputs found
Exploratory electromagnetic thruster research, phase 3, 23 June - 23 December 1969
Performance evaluation of MPD arc jets operating in quasi-steady mode
Investigation of pulsed quasi-steady MPD arc jets
Evaluation of magnetohydrodynamic arc thrusters operating in quasi-steady mode with electrode vapor as propellan
Quaternionic Wave Packets
We compare the behavior of a wave packet in the presence of a complex and a
pure quaternionic potential step. This analysis, done for a gaussian
convolution function, sheds new light on the possibility to recognize
quaternionic deviations from standard quantum mechanics.Comment: 9 pages, 1 figur
Soft and hard QCD dynamics in hadroproduction of charmonium
Both hard and soft QCD dynamics are important in charmonium production, as
presented here through a next-to-leading order QCD matrix element calculation
combined with the colour evaporation model. Observed and
distributions of in hadroproduction at fixed target and
collider energies are reproduced. Quite similar results can also be obtained in
a more phenomenologically useful Monte Carlo event generator where the
perturbative production of \ccbar pairs is instead obtained through leading
order matrix elements and the parton shower approximation of the higher order
processes. The soft dynamics may alternatively be described by the soft colour
interaction model, originally introduced in connection with rapidity gaps. We
also discuss the relative rates of different charmonium states and introduce an
improved model for mapping the continuous \ccbar mass spectrum on the physical
charmonium resonances.Comment: 21 pages, 13 eps figure
Soft and hard QCD in charmonium production
Hard and soft QCD dynamics are both important in charmonium hadroproduction,
as presented here through a next-to-leading order QCD matrix element
calculation combined with the colour evaporation model. Observed and
distributions of in hadroproduction are reproduced. Quite
similar results can also be obtained with a Monte Carlo event generator where
\ccbar pairs are instead produced through leading order matrix elements and the
parton shower approximation of higher order processes. The soft dynamics may
alternatively be described by the soft colour interaction model. We also
discuss the relative rates of different charmonium states and introduce an
improved model for mapping the continuous ccbar mass spectrum on the physical
charmonium resonances.Comment: Presented at Pan American Advanced Studies Institute (PASI 2002),
Campos do Jord\~ao, Brazil, January 7-18, 200
Pomerons and Lattices: a Progress Report
We report on some attempts to use lattice QCD to investigate topics in strong
interactions phenomenology which are usually interpreted in terms of soft
Pomeron exchange.Comment: Talk presented at LAT96, 3 pages, Latex, one style file and 2
PostScript pictures include
Multichromatic colour-magnitude diagrams of the globular cluster NGC 6366
We present multichromatic isochrone fits to the colour-magnitude data of the
globular cluster NGC 6366, based on Hubble Space Telescope Advanced Camera for
Surveys/Wide Field Channel and Southern Astrophysical Research photometric
data. We corrected the photometric data for differential reddening and
calculated the mean ridge line of the colour-magnitude diagrams. We compared
the isochrones of Dartmouth Stellar Evolution Database and PAdova and TRieste
Stellar Evolution Code both with microscopic diffusion starting on the main
sequence. Bracketing all previous determinations of this cluster, we tested
metallicities from [Fe/H]=-1.00 to [Fe/H]=-0.50, and ages from 9 to 13 Gyr.
After determining the total to selective extinction ratio only from stars
belonging to this cluster, R_V=3.06+/-0.14, we found the parameters for this
cluster to be E(B-V)=0.69+/-0.02(int)+/-0.04(ext),
(m-M)_V=15.02+/-0.07(int)+/-0.13(ext), Age=11+/-1.15 Gyr. Evolutionary models
fail to reproduce the low-Teff sequence in multiband colour-magnitude diagrams,
indicating that they still have an incomplete physics. We found that the
Dartmouth Stellar Evolution Database isochrones better fit the subgiant branch
and low main sequence than the PAdova and TRieste Stellar Evolution Code.Comment: 9 pages, 5 figure
Investigating the photo-oxidation of model indoor air pollutants using field asymmetric ion mobility spectrometry
We have developed a versatile measurement system utilising field asymmetric ion mobility spectrometry (FAIMS) to study the photocatalytic degradation of VOC’s at concentrations comparable to indoor air. FAIMS allows continuous monitoring of chemical species in the gas phase, whilst having a high separation selectivity and sensitivity, so can be used to identify multiple species concurrently at ppb concentrations, which are clear advantages over traditional characterization techniques used in photocatalytic air purification such as gas chromatography. Here we demonstrate the methodology with the photo-oxidation of 2-propanol, ethanol and acetone using a commercial titanium dioxide felt. To the best of our knowledge, this is the first time FAIMS has been used in photocatalytic air purification applications.The authors are grateful for the financial support from the ERC, under grant number 259619 PHOTO EM and grant number 620298 PHOTO AIR (Proof of Concept).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.jphotochem.2015.07.00
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