8,877 research outputs found
Numerical Simulation of III-V Solar Cells Using D-AMPS
Numerical simulation of devices plays a crucial role in their design, performance prediction, and comprehension of the fundamental phenomena ruling their operation. Here, we present results obtained using the code D-AMPS-1D, that was conveniently modified to consider the particularities of III-V solar cell devices. This work, that is a continuation of a previous paper regarding solar cells for space applications, is focused on solar cells structures than find application for terrestrial use under concentrated solar illumination. The devices were fabricated at the Solar Energy Institute of the Technical University of Madrid (UPM). The first simulations results on InGaP cells are presented. The influence of band offsets and band bending at the window-emitter interface on the quantum efficiency was studied. A remarkable match of the experimental quantum efficiency was obtained. Finally, numerical simulation of single junction n-p InGaP-Ge solar cells was performed
Multiplexing of encrypted data using fractal masks
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.37.002895. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawIn this Letter, we present to the best of our knowledge a new all-optical technique for multiple-image encryption and multiplexing, based on fractal encrypting masks. The optical architecture is a joint transform correlator. The multiplexed encrypted data are stored in a photorefractive crystal. The fractal parameters of the key can be easily tuned to lead to a multiplexing operation without cross talk effects. Experimental results that support the potential of the method are presented.This research was performed under grants TWAS-UNESCO Associateship Scheme at Centres of Excellence in the South, CONICET No. 0863 (Argentina), ANCYT PICT 1167 (Argentina), and Facultad de Ingenieria, Universidad Nacional de La Plata No. 11/I125 (Argentina), Sostenibilidad 2011-2012, and CODI (Universidad de Antioquia-Colombia). W. D. Furlan and J. A. Monsoriua acknowledge financial support from Ministerio de Economia y Competitividad (grant FIS2011-23175), Generalitat Valenciana (grant PROMETEO2009-077), and Universitat Politecnica de Valencia (grants PAID-05-11 and PAID-02-11), Spain.Barrera, J.; Tebaldi, M.; Amaya, D.; Furlan, W.; Monsoriu Serra, JA.; Bolognini, NA.; Torroba, RD.... (2012). Multiplexing of encrypted data using fractal masks. Optics Letters. 37(14):2895-2897. doi:10.1364/OL.37.002895S289528973714Refregier, P., & Javidi, B. (1995). Optical image encryption based on input plane and Fourier plane random encoding. Optics Letters, 20(7), 767. doi:10.1364/ol.20.000767Matoba, O., & Javidi, B. (1999). Encrypted optical memory system using three-dimensional keys in the Fresnel domain. Optics Letters, 24(11), 762. doi:10.1364/ol.24.000762Unnikrishnan, G., Joseph, J., & Singh, K. (2000). Optical encryption by double-random phase encoding in the fractional Fourier domain. Optics Letters, 25(12), 887. doi:10.1364/ol.25.000887Nomura, T. (2000). Polarization encoding for optical security systems. Optical Engineering, 39(9), 2439. doi:10.1117/1.1288369Tebaldi, M., Furlan, W. D., Torroba, R., & Bolognini, N. (2009). Optical-data storage-readout technique based on fractal encrypting masks. Optics Letters, 34(3), 316. doi:10.1364/ol.34.000316Situ, G., & Zhang, J. (2005). Multiple-image encryption by wavelength multiplexing. Optics Letters, 30(11), 1306. doi:10.1364/ol.30.001306Liu, Z., & Liu, S. (2007). Double image encryption based on iterative fractional Fourier transform. Optics Communications, 275(2), 324-329. doi:10.1016/j.optcom.2007.03.039Hwang, H.-E., Chang, H. T., & Lie, W.-N. (2009). Multiple-image encryption and multiplexing using a modified Gerchberg-Saxton algorithm and phase modulation in Fresnel-transform domain. Optics Letters, 34(24), 3917. doi:10.1364/ol.34.003917Matoba, O., & Javidi, B. (1999). Encrypted optical storage with angular multiplexing. Applied Optics, 38(35), 7288. doi:10.1364/ao.38.007288Fredy Barrera, J., Henao, R., Tebaldi, M., Torroba, R., & Bolognini, N. (2006). Multiplexing encryption–decryption via lateral shifting of a random phase mask. Optics Communications, 259(2), 532-536. doi:10.1016/j.optcom.2005.09.027Henao, R., Rueda, E., Barrera, J. F., & Torroba, R. (2010). Noise-free recovery of optodigital encrypted and multiplexed images. Optics Letters, 35(3), 333. doi:10.1364/ol.35.000333Barrera, J. F., Henao, R., Tebaldi, M., Torroba, R., & Bolognini, N. (2006). Multiple image encryption using an aperture-modulated optical system. Optics Communications, 261(1), 29-33. doi:10.1016/j.optcom.2005.11.055Mosso, F., Barrera, J. F., Tebaldi, M., Bolognini, N., & Torroba, R. (2011). All-optical encrypted movie. Optics Express, 19(6), 5706. doi:10.1364/oe.19.005706Monsoriu, J. A., Saavedra, G., & Furlan, W. D. (2004). Fractal zone plates with variable lacunarity. Optics Express, 12(18), 4227. doi:10.1364/opex.12.00422
Separate ways: The Mass-Metallicity Relation does not strongly correlate with Star Formation Rate in SDSS-IV MaNGA galaxies
We present the integrated stellar mass-metallicity relation (MZR) for more
than 1700 galaxies included in the integral field area SDSS-IV MaNGA survey.
The spatially resolved data allow us to determine the metallicity at the same
physical scale (effective radius in arcsecs, ) using a
heterogeneous set of ten abundance calibrators. Besides scale factors, the
shape of the MZR is similar for all calibrators, consistent with those reported
previously using single-fiber and integral field spectroscopy. We compare the
residuals of this relation against the star formation rate (SFR) and specific
SFR (sSFR). We do not find a strong secondary relation of the MZR with either
SFR or the sSFR for any of the calibrators, in contrast with previous
single-fiber spectroscopic studies. Our results agree with an scenario in which
metal enrichment happens at local scales, with global outflows playing a
secondary role in shaping the chemistry of galaxies and cold-gas inflows
regulating the stellar formation.Comment: 10 pages, 9 Figures. Accepted for publication in Ap
PAINLEVE' ANALYSIS AND EXACT SOLUTIONS FOR THE COUPLET BURGERS SYSTEM
We perform the Painlev\ue8 test to a system of two coupled Burgers-type
equations which fails to satisfy the Painlev\ue8 test. In order to obtain a class of
solutions, we use a slightly modified version of the test. These solutions are
expressed in terms of the Airy functions. We also give the travelling wave
solutions,expressed in terms of the trigonometric and hyperbolic functions
Distribución ecológica de las ascidias en las costas de Cataluña e Islas Baleares (Mediterráneo Occidental)
Event Recognition Using Signal Spectrograms in Long Pulse Experiments
As discharge duration increases, real-time complex analysis of the signal becomes more important. In this context, data acquisition and processing systems must provide models for designing experiments which use event oriented plasma control. One example of advanced data analysis is signal classification. The off-line statistical analysis of a large number of discharges provides information to develop algorithms for the determination of the plasma parameters from measurements of magnetohydrodinamic waves, for example, to detect density fluctuations induced by the Alfvén cascades using morphological patterns. The need to apply different algorithms to the signals and to address different processing algorithms using the previous results necessitates the use of an event-based experiment. The Intelligent Test and Measurement System platform is an example of architecture designed to implement distributed data acquisition and real-time processing systems. The processing algorithm sequence is modeled using an event-based paradigm. The adaptive capacity of this model is based on the logic defined by the use of state machines in SCXML. The Intelligent Test and Measurement System platform mixes a local multiprocessing model with a distributed deployment of services based on Jini
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