12,924 research outputs found
Management of Potential Fishery Resources
The prevailing situation in the fisheries sector in many
countries of the world can be briefly stated as (1) insufficient
information on fish resources, (2) diminishing stock and (3)
conflicting uses of coastal areas and types of fishing. Since
there is free accessibility to the exploitable resources in the sea,
the natural tendency is to make more and more without regard
to the real availability. The need for fishery management
assumed importance in recent years on account of the uncontrolled,
or rather reckless, exploitation of the resources in
many countries [leading to depletion of stock. Although
according to available information the level of exploitation of
the fishery resources in our country in general is far below the
optimum level, there seems to be too much concentration in,
certain areas and in respect to certain specks which perhaps is a
reflection of the lack of fishery management policies or their
implementation
Comparison of post-Newtonian templates for extreme mass ratio inspirals
Extreme mass ratio inspirals (EMRIs), the inspirals of compact objects into
supermassive black holes, are important gravitational wave sources for the
Laser Interferometer Space Antenna (LISA). We study the performance of various
post-Newtonian (PN) template families relative to the high precision numerical
waveforms in the context of EMRI parameter estimation with LISA. Expressions
for the time domain waveforms TaylorT1, TaylorT2, TaylorT3, TaylorT4 and
TaylorEt are derived up to 22PN order, i.e ( is the
characteristic velocity of the binary) beyond the Newtonian term, for a test
particle in a circular orbit around a Schwarzschild black hole. The phase
difference between the above 22PN waveform families and numerical waveforms are
evaluated during two-year inspirals for two prototypical EMRI systems with mass
ratios and . We find that the dephases (in radians) for
TaylorT1 and TaylorT2, respectively, are about () and
() for mass ratio (). This suggests that
using 22PN TaylorT1 or TaylorT2 waveforms for parameter estimation of EMRIs
will result in accuracies comparable to numerical waveform accuracy for most of
the LISA parameter space. On the other hand, from the dephase results, we find
that TaylorT3, TaylorT4 and TaylorEt fare relatively poorly as one approaches
the last stable orbit. This implies that, as for comparable mass binaries using
the 3.5PN phase of waveforms, the 22PN TaylorT3 and TaylorEt approximants do
not perform well enough for the EMRIs. The reason underlying the poor
performance of TaylorT3, TaylorT4 and TaylorEt relative to TaylorT1 and
TaylorT2 is finally examined.Comment: 10 page
Thickness dependent studies of hetero-junction solar cell synthesized on quartz substrate by spray pyrolysis technique
36-43Variable thickness hetero-junction solar cells synthesized on quartz substrate by spray pyrolysis technique synthesized quartz based solar cells have been found to possess cell parameters such as open circuit voltage, saturation current density, fill factor and efficiency in the range of 191 – 449 mV, 2×10-9 – 0.11×10-6 A cm-2, 15 – 20 % and 0.2×10-9 – 3.35×10-6 % at 206 mW/cm2 (at air mass 5.6), respectively. Series and shunt resistance of the solar cells have been found to vary with the thickness of semiconductor films. Thick film solar cells are found to possess reasonably good cell parameters compared to thin film solar cells due to enhancement of charge concentration, mobility, grain size, variation of optical band gap, excesses atomic percentage of Ti, Cu, Te, Sn elements in TiO2, CuO, CdTe, SnS films and less structural defects, increment of activation energy as well as existence of mixed phase at the Schottky barrier. The optical response of hetero-junction solar cells is found to be thickness dependent. Good rectifying characteristic has been reported in the present work for both thick and thin hetero-junction solar cells. All the measurements have been performed in air without protection against oxygen gas or moisture, which shows the stability of spray pyrolyzed thin films
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