643 research outputs found
125 Gbps Pre-Compensated Nonlinear Frequency-Division Multiplexed Transmission
Record-high data rate of 125 Gb/s and SE over 2 bits/s/Hz in burst-mode
single-polarization NFDM transmissions were achieved over 976 km of SSMF with
EDFA-only amplification by transmitting and processing 222 32 QAM-modulated
nonlinear subcarriers simultaneouslyComment: This paper will be presented at ECOC 2017, Gothenburg, Swede
Does the Cross-Talk Between Nonlinear Modes Limit the Performance of NFDM Systems?
We show a non-negligible cross-talk between nonlinear modes in Nonlinear
Frequency-Division Multiplexed system when data is modulated over the nonlinear
Fourier spectrum, both the continuous spectrum and the discrete spectrum, and
transmitted over a lumped amplified fiber link. We evaluate the performance
loss if the cross-talks are neglected.Comment: Invited paper, European Conference on Optical Communication (ECOC
2017), Sept. 2017, p. Th.1.D.
Interaction of point sources and vortices for incompressible planar fluids
We consider a new system of differential equations which is at the same time
gradient and locally Hamiltonian. It is obtained by just replacing a factor in
the equations of interaction for N point vortices, and it is interpreted as an
interaction of N point sources. Because of the local Hamiltonian structure and
the symmetries it obeys, it does possess some of the first integrals that
appear in the N vortex problem. We will show that binary collisions are easily
blown up in this case since the equations of motion are of first order. This
method may be easily generalized to the blow up of higher order collisions. We
then generalize the model further to interactions of sources and vortices.Comment: 9 page
Role perceptions and role performance of instructional supervisors as perceived by teachers and supervisors in the public schools of Qatar.
Euler configurations and quasi-polynomial systems
In the Newtonian 3-body problem, for any choice of the three masses, there
are exactly three Euler configurations (also known as the three Euler points).
In Helmholtz' problem of 3 point vortices in the plane, there are at most three
collinear relative equilibria. The "at most three" part is common to both
statements, but the respective arguments for it are usually so different that
one could think of a casual coincidence. By proving a statement on a
quasi-polynomial system, we show that the "at most three" holds in a general
context which includes both cases. We indicate some hard conjectures about the
configurations of relative equilibrium and suggest they could be attacked
within the quasi-polynomial framework.Comment: 21 pages, 6 figure
Echoes in classical dynamical systems
Echoes arise when external manipulations to a system induce a reversal of its
time evolution that leads to a more or less perfect recovery of the initial
state. We discuss the accuracy with which a cloud of trajectories returns to
the initial state in classical dynamical systems that are exposed to additive
noise and small differences in the equations of motion for forward and backward
evolution. The cases of integrable and chaotic motion and small or large noise
are studied in some detail and many different dynamical laws are identified.
Experimental tests in 2-d flows that show chaotic advection are proposed.Comment: to be published in J. Phys.
Effective action of magnetic monopole in three-dimensional electrodynamics with massless matter and gauge theories of superconductivity
We compute one-loop effective action of magnetic monopole in
three-dimensional electrodynamics of massless bosons and fermions and find that
it contains an infrared logarithm. So, when the number of massless matter
species is sufficiently large, monopoles are suppressed and in the weak
coupling limit charged particles are unconfined. This result provides some
support to gauge theories of high-temperature superconductors. It also provides
a mechanism by which interlayer tunneling of excitations with one unit of the
ordinary electric charge can be suppressed while that of a doubly charged
object is allowed.Comment: 8 pages, LATEX, UCLA/93/TEP/41 (the last sentence of the paragraph
concerning applications at the end of the paper has been deleted; mailing
problems have been corrected
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