31,914 research outputs found
Analytical mode normalization and resonant state expansion for optical fibers - an efficient tool to model transverse disorder
We adapt the resonant state expansion to optical fibers such as capillary and
photonic crystal fibers. As a key requirement of the resonant state expansion
and any related perturbative approach, we derive the correct analytical
normalization for all modes of these fiber structures, including leaky modes
that radiate energy perpendicular to the direction of propagation and have
fields that grow with distance from the fiber core. Based on the normalized
fiber modes, an eigenvalue equation is derived that allows for calculating the
influence of small and large perturbations such as structural disorder on the
guiding properties. This is demonstrated for two test systems: a capillary
fiber and an endlessly single mode fiber.Comment: 10 pages, 4 figure
Characterization of solar cells for space applications. Volume 1: Electrical characteristics of OCLI violet solar cells as a function of intensity and temperature
Electrical characteristics of OCLI violet N/P silicon solar cells are presented in graphical and tabular format as function of solar illumination intensity and temperature
Characterization of solar cells for space applications. Volume 5: Electrical characteristics of OCLI 225-micron MLAR wraparound cells as a function of intensity, temperature, and irradiation
Computed statistical averages and standard deviations with respect to the measured cells for each intensity temperature measurement condition are presented. Display averages and standard deviations of the cell characteristics in a two dimensional array format are shown: one dimension representing incoming light intensity, and another, the cell temperature. Programs for calculating the temperature coefficients of the pertinent cell electrical parameters are presented, and postirradiation data are summarized
Comparison of Josephson vortex flow transistors with different gate line configurations
We performed numerical simulations and experiments on Josephson vortex flow
transistors based on parallel arrays of YBa2Cu3O(7-x) grain boundary junctions
with a cross gate-line allowing to operate the same devices in two different
modes named Josephson fluxon transistor (JFT) and Josephson fluxon-antifluxon
transistor (JFAT). The simulations yield a general expression for the current
gain vs. number of junctions and normalized loop inductance and predict higher
current gain for the JFAT. The experiments are in good agreement with
simulations and show improved coupling between gate line and junctions for the
JFAT as compared to the JFT.Comment: 3 pages, 6 figures, accept. for publication in Appl. Phys. Let
Paraunitary oversampled filter bank design for channel coding
Oversampled filter banks (OSFBs) have been considered for channel coding, since their redundancy can be utilised to permit the detection and correction of channel errors. In this paper, we propose an OSFB-based channel coder for a correlated additive Gaussian noise channel, of which the noise covariance matrix is assumed to be known. Based on a suitable factorisation of this matrix, we develop a design for the decoder's synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction through paraunitarity of the filter bank. We demonstrate that this approach can lead to a significant reduction of the noise interference by exploiting both the correlation of the channel and the redundancy of the filter banks. Simulation results providing some insight into these mechanisms are provided
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