10,203 research outputs found
The design of a Pulse Position Modulated /PPM/ optical communication system
Design of pulse position modulation optical communication syste
Communication theory for the free space optical channel Interim technical report
Quantum detectors, noise mechanisms, and application to optical communication theor
Computing Matveev's complexity via crystallization theory: the boundary case
The notion of Gem-Matveev complexity has been introduced within
crystallization theory, as a combinatorial method to estimate Matveev's
complexity of closed 3-manifolds; it yielded upper bounds for interesting
classes of such manifolds. In this paper we extend the definition to the case
of non-empty boundary and prove that for each compact irreducible and
boundary-irreducible 3-manifold it coincides with the modified Heegaard
complexity introduced by Cattabriga, Mulazzani and Vesnin. Moreover, via
Gem-Matveev complexity, we obtain an estimation of Matveev's complexity for all
Seifert 3-manifolds with base and two exceptional fibers and,
therefore, for all torus knot complements.Comment: 27 pages, 14 figure
Optical deep space communication via relay satellite
The possible use of an optical for high rate data transmission from a deep space vehicle to an Earth-orbiting relay satellite while RF links are envisioned for the relay to Earth link was studied. A preliminary link analysis is presented for initial sizing of optical components and power levels, in terms of achievable data rates and feasible range distances. Modulation formats are restricted to pulsed laser operation, involving bot coded and uncoded schemes. The advantage of an optical link over present RF deep space link capabilities is shown. The problems of acquisition, pointing and tracking with narrow optical beams are presented and discussed. Mathematical models of beam trackers are derived, aiding in the design of such systems for minimizing beam pointing errors. The expected orbital geometry between spacecraft and relay satellite, and its impact on beam pointing dynamics are discussed
Innovation in risky markets. Multinational and domestic firms in the UK regions
This paper analyses the relationship between firm engagement in innovation and perception of market risk. It points to heterogeneity in the behaviour of multinationals (MNEs) versus single domestic firms, emphasising how this relationship changes across regional contexts
Phenomenological interpolation of the inclusive J/psi cross section to proton-proton collisions at 2.76 TeV and 5.5 TeV
We present a study of the inclusive J/psi cross section at 2.76 TeV and 5.5
TeV. The energy dependence of the cross section, rapidity and transverse
momentum distributions are evaluated phenomenologically. Their knowledge is
crucial as a reference for the interpretation of A-A and p-A J/psi results at
the LHC. Our approach is the following: first, we estimate the energy evolution
of the pt-integrated J/psi cross section at mid-rapidity; then, we evaluate the
rapidity dependence; finally, we study the transverse momentum distribution
trend. Whenever possible, both theory driven (based on pQCD predictions) and
functional form (data driven fits) calculations are discussed. Our predictions
are compared with the recently obtained results by the ALICE collaboration in
pp collisions at 2.76 TeV.Comment: 23 pages, 19 figures, updated text+figures, added comparison to ALICE
measurements at 2.76Te
Calculating the 3D magnetic field of ITER for European TBM studies
The magnetic perturbation due to the ferromagnetic test blanket modules
(TBMs) may deteriorate fast ion confinement in ITER. This effect must be
quantified by numerical studies in 3D. We have implemented a combined finite
element method (FEM) -- Biot-Savart law integrator method (BSLIM) to calculate
the ITER 3D magnetic field and vector potential in detail. Unavoidable geometry
simplifications changed the mass of the TBMs and ferritic inserts (FIs) up to
26%. This has been compensated for by modifying the nonlinear ferromagnetic
material properties accordingly. Despite the simplifications, the computation
geometry and the calculated fields are highly detailed. The combination of
careful FEM mesh design and using BSLIM enables the use of the fields
unsmoothed for particle orbit-following simulations. The magnetic field was
found to agree with earlier calculations and revealed finer details. The vector
potential is intended to serve as input for plasma shielding calculations.Comment: In proceedings of the 28th Symposium on Fusion Technolog
Avaliação de protocolos para extração de DNA de Larvas individuais de helmintos.
A genotipagem de helmintos, parasitas do trato gastrintestinal de ruminantes, permite o conhecimento de polimorfismos moleculares relacionados a características adaptativas, dentre as quais se destaca a resistência a produtos anti-helmínticos. Uma vez que a determinação da freqüência gênica e da freqüência aléIica para os polimorfismos de interesse requer a avaliação individual dos helmintos, dificuldades técnicas têm sido encontradas para a recuperação de quantidade suficiente de DNA a partir de larvas para a aplicação de técnicas moleculares. Dessa maneira, o objetivo deste trabalho foi avaliar diferentes protocolos para a extração de DNA de larvas individuais de helmintos Haemonchus contortus e Trichostrongylus colubriformis no estádio L3. Após cultura de fezes de ovinos, por sete dias, as larvas de helmintos foram recuperadas e destinadas á extração de DNA
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