2,358 research outputs found
Wideband Anti-Jamming Based on Free Space Optical Communication and Photonic Signal Processing
We propose and demonstrate an anti-jamming system to defend against wideband jamming attack. Free space optical communication is deployed to provide a reference for jamming cancellation. The mixed signal is processed and separated with photonic signal processing method to achieve large bandwidth. As an analog signal processing method, the cancellation system introduces zero latency. The radio frequency signals are modulated on optical carriers to achieve wideband and unanimous frequency response. With wideband and zero latency, the system meets the key requirements of high speed and real-time communications in transportation systems
Quark-quark Double Scattering and Modified (Anti-)Quark Fragmentation Functions in Nuclei
Quark-quark double scattering in eA DIS and its contribution to quark and
anti-quark fragmentation functions are investigated with the generalized
factorization of the relevant twist-four processes in pQCD. It is shown that
the resulting modifications to quark and anti-quark fragmentation functions are
different. While the numerical size of these effects cannot be determined from
pQCD, the structure of our result leads to a number of qualitative predictions
for the relative size of the effect for different hadrons. These qualitative
predictions agree with the multiplicity ratios for positive and negative
hadrons as observed by HERMES.Comment: 4 pages, 1 figure, talk at "Hard Probes 2006", Asilomar, California,
USA, June 9-16, 200
Parton Energy Loss at Twist-Six in Deeply Inelastic e-A Scattering
Within the framework of the generalized factorization in pQCD, we investigate
the multiple parton scattering and induced parton energy loss at twist-6 in
deeply inelastic e-A scattering with the helicity amplitude approximation. It
is shown that twist-6 processes will give rise to additional nuclear size
dependence of the parton energy loss due to LPM interference effect while its
contribution is power suppressed.Comment: 6 pages, 2 figure
Virtuous medical practice : research report
The Jubilee Centre’s new report, Virtuous Medical Practice, examines the place of character and values in the medical profession in Britain today. Its findings are drawn from a UK-focused multi-methods study of 549 doctors and aspiring doctors at three career stages, first and final year students and experienced doctors
A systematic study of direct photon production in heavy ion collisions
A theoretical derivation of photon bremsstrahlung, induced by the
interactions of an energetic quark in a hot and dense quark-gluon plasma, is
given in the framework of the reaction operator approach. For the physically
relevant case of hard jet production, followed by few in-medium interactions,
we find that the Landau-Pomeranchuk-Migdal suppression of the bremsstrahlung
photon intensity is much stronger than in the previously discussed limit of
on-shell quarks and a large number of soft scatterings. We present the first
systematic study of direct photon production in minimum bias d+Cu and d+Au and
central Cu+Cu and Au+Au heavy ion collisions at the Relativistic Heavy Ion
Collider at center of mass energies of 62.4 GeV and 200 GeV. We find that the
contribution of the final-state photon production at pT < 5 GeV is limited to
35%, and at high transverse momenta, the modification of the direct photon
cross section is dominated by initial-state cold nuclear matter effects.Comment: Final version published in PLB. Added comments, 2 references and
discussion in relation to SDIS observable
Hybrid phase-change Lattice Boltzmann simulation of vapor condensation on vertical subcooled walls
Saturated vapor condensation on homogenous and heterogeneous subcooled walls is presented in this study by adopting a hybrid phase-change multiple-relaxation-time Lattice Boltzmann model. The effects of wall wettability on the condensation process, including droplets’ growth, coalescence and falling, and the influence of vapor flow to condensation are investigated. The results demonstrate that the heat fluxes around the triple-phase contact lines are higher than that in other cold areas in homogeneous subcooled walls, which actually indicates the fact that filmwise condensation is preventing the continuous condensation process. Furthermore, the dropwise condensation can be formed more easily on the heterogeneous surface with a mixed surface wettability. At last, the dynamic process of condensation of continuous vapor flow is also investigated by considering the homogenous and heterogeneous subcooled surfaces. The results show that the heterogeneous surface with mixed wettability doesn’t contribute to the formation, growth of droplets, when compared to the homogeneous surface. It is expected that this study can bring more attentions to simulate condensation using multiphase LBM for complex geometries in heat transfer community
- …