505 research outputs found
Modeling a Slicer Mirror Using Zemax User-Defined Surface
A slicer mirror is a complex surface composed by many tilted and decentered
mirrors sub-surfaces. The major difficulty to model such a complex surface is
the large number of parameters used to define it. The Zemax's
multi-configuration mode is usually used to specify each parameters (tilts,
curvatures, decenters) for each mirror sub-surface which are then considered
independently. Otherwise making use of the User-Defined Surface (UDS-DLL) Zemax
capability, we are able to consider the set of sub-surfaces as a whole surface.
In this paper, we present such a UDS-DLL tool comparing its performance with
those of the classical multi-configuration mode. In particular, we explore the
use of UDS-DLL to investigate the cross-talk due to the diffraction on the
slicer array mirrors which has been a burden task when using
multi-configuration mode.Comment: Submitted to the proceedings of the Durham Integral Field
Spectroscopy Workshop July 4th-8th 200
Development of an experimental 10 T Nb3Sn dipole magnet for the CERN LHC
An experimental 1-m long twill aperture dipole magnet developed using a high-current Nb3Sn conductor in order to attain a magnetic field well beyond 10 T at 4.2 K is described. The emphasis in this Nb3Sn project is on the highest possible field within the known Large Hadron Collider (LHC) twin-aperture configuration. A design target of 11.5 T was chosen
Projectrapportage Cooperatief pootvis productiecentrum voor de Nederlandse mariene viskweek sector
Het doel van dit project is het demonstreren van de haalbaarheid van een coöperatief productiecentrum voor tarbot en tong pootvis ten behoeve van de Nederlandse platviskweek sector. De rapportage gaat voornamelijk in op de kennisvragen m.b.t. de kosten en de technische haalbaarheid van een pootvis productiesysteem
Polymer translocation through a nanopore - a showcase of anomalous diffusion
The translocation dynamics of a polymer chain through a nanopore in the
absence of an external driving force is analyzed by means of scaling arguments,
fractional calculus, and computer simulations. The problem at hand is mapped on
a one dimensional {\em anomalous} diffusion process in terms of reaction
coordinate (i.e. the translocated number of segments at time ) and shown
to be governed by an universal exponent whose
value is nearly the same in two- and three-dimensions. The process is described
by a {\em fractional} diffusion equation which is solved exactly in the
interval with appropriate boundary and initial conditions. The
solution gives the probability distribution of translocation times as well as
the variation with time of the statistical moments: , and which provide full description of the diffusion process. The
comparison of the analytic results with data derived from extensive Monte Carlo
(MC) simulations reveals very good agreement and proves that the diffusion
dynamics of unbiased translocation through a nanopore is anomalous in its
nature.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev.
Driven polymer translocation through a nanopore: a manifestation of anomalous diffusion
We study the translocation dynamics of a polymer chain threaded through a
nanopore by an external force. By means of diverse methods (scaling arguments,
fractional calculus and Monte Carlo simulation) we show that the relevant
dynamic variable, the translocated number of segments , displays an {\em
anomalous} diffusive behavior even in the {\em presence} of an external force.
The anomalous dynamics of the translocation process is governed by the same
universal exponent , where is the Flory
exponent and - the surface exponent, which was established recently
for the case of non-driven polymer chain threading through a nanopore. A closed
analytic expression for the probability distribution function , which
follows from the relevant {\em fractional} Fokker - Planck equation, is derived
in terms of the polymer chain length and the applied drag force . It is
found that the average translocation time scales as . Also the corresponding time dependent
statistical moments, and reveal unambiguously the anomalous nature of the translocation
dynamics and permit direct measurement of in experiments. These
findings are tested and found to be in perfect agreement with extensive Monte
Carlo (MC) simulations.Comment: 6 pages, 4 figures, accepted to Europhys. Lett; some references were
supplemented; typos were correcte
Effect of External Noise Correlation in Optical Coherence Resonance
Coherence resonance occurring in semiconductor lasers with optical feedback
is studied via the Lang-Kobayashi model with external non-white noise in the
pumping current. The temporal correlation and the amplitude of the noise have a
highly relevant influence in the system, leading to an optimal coherent
response for suitable values of both the noise amplitude and correlation time.
This phenomenon is quantitatively characterized by means of several statistical
measures.Comment: RevTeX, 4 pages, 7 figure
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