99,849 research outputs found
Polarization-dependent discharge in fibers of semiconducting ladder-type polymer
We report results on polarization-dependent photoinduced discharge in
oriented fibers and films of ladder-type, electron-transporting polymer poly
(benzimidazobenzophenanthroline), BBL. The photocarrier generation efficiency
in the fiber which is indicated by the rate of discharge, is found to be
distinctly higher for light polarized parallel to the fiber axis as compared to
the radially perpendicular direction . Similar results, with photocarrier
generation efficiency anisotropy ~ 10 are obtained for oriented films. These
observations are different from previously obtained results on
polyparaphenylenevinylene (PPV). The results are compared with the
polarization-dependent steady- state photoconductivity measurements. We
interpret these results on the basis of molecular and macroscopic features of
the material.Comment: This article has been accepted for publication in applied physics
letters and tentatively to be published in March 12, 2001 issu
Simultaneous EUV and Radio Observations of Bidirectional Plasmoids Ejection During Magnetic Reconnection
We present a multiwavelength study of the X-class flare, which occurred in
active region (AR) NOAA 11339 on 3 November 2011. The EUV images recorded by
SDO/AIA show the activation of a remote filament (located north of the AR) with
footpoint brightenings about 50 min prior to the flare occurrence. The kinked
filament rises-up slowly and after reaching a projected height of ~49 Mm, it
bends and falls freely near the AR, where the X-class flare was triggered.
Dynamic radio spectrum from the Green Bank Solar Radio Burst Spectrometer
(GBSRBS) shows simultaneous detection of both positive and negative drifting
pulsating structures (DPSs) in the decimetric radio frequencies (500-1200 MHz)
during the impulsive phase of the flare. The global negative DPSs in solar
flares are generally interpreted as a signature of electron acceleration
related to the upward moving plasmoids in the solar corona. The EUV images from
AIA 94 \AA reveal the ejection of multiple plasmoids, which move simultaneously
upward and downward in the corona during the magnetic reconnection. The
estimated speeds of the upward and downward moving plasmoids are ~152-362 and
~83-254 km/s, respectively. These observations strongly support the recent
numerical simulations of the formation and interaction of multiple plasmoids
due to tearing of the current-sheet structure. On the basis of our analysis, we
suggest that the simultaneous detection of both the negative and positive DPSs
is most likely generated by the interaction/coalescence of the multiple
plasmoids moving upward and downward along the current-sheet structure during
the magnetic reconnection process. Moreover, the differential emission measure
(DEM) analysis of the active region reveals presence of a hot flux-rope
structure (visible in AIA 131 and 94 \AA) prior to the flare initiation and
ejection of the multi-temperature plasmoids during the flare impulsive phase.Comment: A&A (accepted), 13 pages, 9 figure
A Compact 1:4 Lossless T-Junction Power Divider Using Open Complementary Split Ring Resonator
This paper presents the size miniaturized and harmonic suppressed lossless 1:4 T-junction unequal power divider using an open complementary split ring resonator (OCSRR). By embedding the OCSRR structure in the microstrip transmission line, slow wave effect is introduced and thereby size reduction is achieved. The dimensions of OCSRR are optimized to reduce the length of high impedance and low impedance quarter-wavelength transmission lines. In our design high impedance line length is reduced to 58.6%, and low impedance line length is reduced to 12% when compared to the conventional quarter wavelength lines. The proposed power divider is having small dimensions of 0.18 λg × 0.33 λg and is 51.94% smaller than the conventional unequal power divider
Parallel matrix inversion techniques
In this paper, we present techniques for inverting sparse, symmetric and positive definite matrices on parallel and distributed computers. We propose two algorithms, one for SIMD implementation and the other for MIMD implementation. These algorithms are modified versions of Gaussian elimination and they take into account the sparseness of the matrix. Our algorithms perform better than the general parallel Gaussian elimination algorithm. In order to demonstrate the usefulness of our technique, we implemented the snake problem using our sparse matrix algorithm. Our studies reveal that the proposed sparse matrix inversion algorithm significantly reduces the time taken for obtaining the solution of the snake problem. In this paper, we present the results of our experimental work
Charged Vaidya-Tikekar model for super compact star
In this work, we explore a class of compact charged spheres that have been
tested against experimental and observational constraints with some known
compact stars candidates. The study is performed by considering the
self-gravitating, charged, isotropic fluids which is more pliability in solving
the Einstein-Maxwell equations. In order to determine the interior geometry, we
utilize the Vaidya-Tikekar geometry for the metric potential with
Riessner-Nordstrom metric as an exterior solution. In this models, we determine
constants after selecting some particular values of M and R, for the compact
objects SAX J1808.4-3658, Her X-1 and 4U 1538-52. The most striking consequence
is that hydrostatic equilibrium is maintained for different forces, and the
situation is clarified by using the generalized Tolman-Oppenheimer-Volkoff
(TOV) equation. In addition to this, we also present the energy conditions,
speeds of sound and compactness of stars that are very much compatible to that
for a physically acceptable stellar model. Arising solutions are also compared
with graphical representations that provide strong evidences for more realistic
and viable models, both at theoretical and astrophysical scale.Comment: 13 Pages, 5 Figures and 4 Table
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