15,800 research outputs found
Large Universality of The Baryon Isgur--Wise Form Factor: The Group Theoretical Approach
In a previous article, it has been proved under the framework of chiral
soliton model that the same Isgur--Wise form factor describes the semileptonic
and decays in the
large limit. It is shown here that this result is in fact independent of
the chiral soliton model and is solely the consequence of the spin-flavor SU(4)
symmetry which arises in the baryon sector in the large limit.Comment: 10 pages in REVTeX, no figure
Viscous wing theory development. Volume 1: Analysis, method and results
Viscous transonic flows at large Reynolds numbers over 3-D wings were analyzed using a zonal viscid-inviscid interaction approach. A new numerical AFZ scheme was developed in conjunction with the finite volume formulation for the solution of the inviscid full-potential equation. A special far-field asymptotic boundary condition was developed and a second-order artificial viscosity included for an improved inviscid solution methodology. The integral method was used for the laminar/turbulent boundary layer and 3-D viscous wake calculation. The interaction calculation included the coupling conditions of the source flux due to the wing surface boundary layer, the flux jump due to the viscous wake, and the wake curvature effect. A method was also devised incorporating the 2-D trailing edge strong interaction solution for the normal pressure correction near the trailing edge region. A fully automated computer program was developed to perform the proposed method with one scalar version to be used on an IBM-3081 and two vectorized versions on Cray-1 and Cyber-205 computers
Linear and nonlinear optical properties of carbon nanotube-coated single-mode optical fiber gratings
This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.002104. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] Single-wall carbon nanotube deposition on the cladding of optical fibers has been carried out to fabricate an all-fiber nonlinear device. Two different nanotube deposition techniques were studied. The first consisted of repeatedly immersing the optical fiber into a nanotube supension, increasing the thickness of the coating in each step. The second deposition involved wrapping a thin film of nanotubes around the optical fiber. For both cases, interaction of transmitted light through the fiber core with the external coating was assisted by the cladding mode resonances of a tilted fiber Bragg grating. Ultrafast nonlinear effects of the nanotube-coated fiber were measured by means of a pump-probe pulses experiment. © 2011 Optical Society of America.This work was financially supported by the European Commission under the FP7 EURO-FOS Network of Excellence (ICT-2007-2-224402), the Ministerio de Educación y Ciencia SINADEC project (TEC2008-06333), and the Natural Sciences and Engineering Research Council of Canada (NSERC). The work of G. E. Villanueva was supported by the Ministerio de Educación y Ciencia Formación de Profesorado Universitario programs. The work of P. Pérez-Millán was supported by the Juan de la Cierva program, JCI-2009-05805.Villanueva Ibáñez, GE.; Jakubinek, M.; Simard, B.; Oton Nieto, CJ.; Matres Abril, J.; Shao, L.; Pérez Millán, P.... (2011). Linear and nonlinear optical properties of carbon nanotube-coated single-mode optical fiber gratings. Optics Letters. 36(11):2104-2106. https://doi.org/10.1364/OL.36.002104S210421063611Sakakibara, Y., Rozhin, A. G., Kataura, H., Achiba, Y., & Tokumoto, M. (2005). Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors. Japanese Journal of Applied Physics, 44(4A), 1621-1625. doi:10.1143/jjap.44.1621Chow, K. K., Yamashita, S., & Song, Y. W. (2009). A widely tunable wavelength converter based on nonlinear polarization rotation in a carbon-nanotube-deposited D-shaped fiber. Optics Express, 17(9), 7664. doi:10.1364/oe.17.007664Set, S. Y., Yaguchi, H., Tanaka, Y., & Jablonski, M. (2004). Ultrafast Fiber Pulsed Lasers Incorporating Carbon Nanotubes. IEEE Journal of Selected Topics in Quantum Electronics, 10(1), 137-146. doi:10.1109/jstqe.2003.822912Chow, K. K., Tsuji, M., & Yamashita, S. (2010). Single-walled carbon-nanotube-deposited tapered fiber for four-wave mixing based wavelength conversion. Applied Physics Letters, 96(6), 061104. doi:10.1063/1.3304789Chow, K. K., & Yamashita, S. (2009). Four-wave mixing in a single-walled carbon-nanotube-deposited D-shaped fiber and its application in tunable wavelength conversion. Optics Express, 17(18), 15608. doi:10.1364/oe.17.015608Choi, S. Y., Rotermund, F., Jung, H., Oh, K., & Yeom, D.-I. (2009). Femtosecond mode-locked fiber laser employing a hollow optical fiber filled with carbon nanotube dispersion as saturable absorber. Optics Express, 17(24), 21788. doi:10.1364/oe.17.021788Chan, C.-F., Chen, C., Jafari, A., Laronche, A., Thomson, D. J., & Albert, J. (2007). Optical fiber refractometer using narrowband cladding-mode resonance shifts. Applied Optics, 46(7), 1142. doi:10.1364/ao.46.001142Kingston, C. T., Jakubek, Z. J., Dénommée, S., & Simard, B. (2004). Efficient laser synthesis of single-walled carbon nanotubes through laser heating of the condensing vaporization plume. Carbon, 42(8-9), 1657-1664. doi:10.1016/j.carbon.2004.02.020Jakubinek, M. B., Johnson, M. B., White, M. A., Guan, J., & Simard, B. (2010). Novel Method to Produce Single-Walled Carbon Nanotube Films and Their Thermal and Electrical Properties. Journal of Nanoscience and Nanotechnology, 10(12), 8151-8157. doi:10.1166/jnn.2010.3014Vallaitis, T., Koos, C., Bonk, R., Freude, W., Laemmlin, M., Meuer, C., … Leuthold, J. (2008). Slow and fast dynamics of gain and phase in a quantum dot semiconductor optical amplifier. Optics Express, 16(1), 170. doi:10.1364/oe.16.00017
Mass spectrometric determination of lithium in seawater
Lithium concentrations in Pacific Ocean waters to depths of over 4,000 m have been determined using isotope dilution techniques with a mass spectrometer. Values varied about 170 µg/L and showed a covariance with the salinity
Twisted and Nontwisted Bifurcations Induced by Diffusion
We discuss a diffusively perturbed predator-prey system. Freedman and
Wolkowicz showed that the corresponding ODE can have a periodic solution that
bifurcates from a homoclinic loop. When the diffusion coefficients are large,
this solution represents a stable, spatially homogeneous time-periodic solution
of the PDE. We show that when the diffusion coefficients become small, the
spatially homogeneous periodic solution becomes unstable and bifurcates into
spatially nonhomogeneous periodic solutions.
The nature of the bifurcation is determined by the twistedness of an
equilibrium/homoclinic bifurcation that occurs as the diffusion coefficients
decrease. In the nontwisted case two spatially nonhomogeneous simple periodic
solutions of equal period are generated, while in the twisted case a unique
spatially nonhomogeneous double periodic solution is generated through
period-doubling.
Key Words: Reaction-diffusion equations; predator-prey systems; homoclinic
bifurcations; periodic solutions.Comment: 42 pages in a tar.gz file. Use ``latex2e twisted.tex'' on the tex
files. Hard copy of figures available on request from
[email protected]
Controlling extended systems with spatially filtered, time-delayed feedback
We investigate a control technique for spatially extended systems combining
spatial filtering with a previously studied form of time-delay feedback. The
scheme is naturally suited to real-time control of optical systems. We apply
the control scheme to a model of a transversely extended semiconductor laser in
which a desirable, coherent traveling wave state exists, but is a member of a
nowhere stable family. Our scheme stabilizes this state, and directs the system
towards it from realistic, distant and noisy initial conditions. As confirmed
by numerical simulation, a linear stability analysis about the controlled state
accurately predicts when the scheme is successful, and illustrates some key
features of the control including the individual merit of, and interplay
between, the spatial and temporal degrees of freedom in the control.Comment: 9 pages REVTeX including 7 PostScript figures. To appear in Physical
Review
Exploring a rheonomic system
A simple and illustrative rheonomic system is explored in the Lagrangian
formalism. The difference between Jacobi's integral and energy is highlighted.
A sharp contrast with remarks found in the literature is pointed out. The
non-conservative system possess a Lagrangian not explicitly dependent on time
and consequently there is a Jacobi's integral. The Lagrange undetermined
multiplier method is used as a complement to obtain a few interesting
conclusion
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