Indic, P; Pratap, R; Nampoori, V P N; Pradhan, N(International Journal of Neuroscience, 1999)
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Abstract:
We propose to show in this paper, that the time series obtained from biological systems such as human brain are invariably nonstationary because of different time scales involved in the dynamical process. This makes the invariant parameters time dependent. We made a global analysis of the EEG data obtained from the eight locations on the skull space and studied simultaneously the dynamical characteristics from various parts of the brain. We have proved that the dynamical parameters are sensitive to the time scales and hence in the study of brain one must identify all relevant time scales involved in the process to get an insight in the working of brain.
Reactive extrusion is an attractive means of polymer processing since the shaping
and reaction take place in a single operation. In this paper we report the silane
grafting of polyethylenes in a single screw extruder. The optimum conditions for
silane grafting, viz. temperature, shear rate, silane and DCP concentrations, were
determined on a torque rheometer and then actual extrusion was performed
using these conditions. The study shows that an optimum low level of grafting/
crosslinking can be introduced into polyethylene during its extrusion for better
mechanical behavior and=or thermal stability without affecting the processability.
Sudha Kartha, C; Sreekumar, K; Rani, Joseph; Subramanyan, N V; Nimmi, K P; Pramitha, V(Optical Society of America, April 14, 2009)
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Abstract:
Incorporation of silver ions into a dye-sensitized poly(vinyl alcohol)/acrylamide photopolymer is observed
to give better performance compared to other metal-ion-doped photopolymer holographic recording
media. Plane-wave transmission gratings were recorded in the photopolymer films using a He–Ne
laser, and various holographic parameters were optimized so as to explore maximum potential of the
material for various holographic applications. Silver-doped films showed good energy sensitivity,
and gratings recorded in optimized film exhibited a diffraction efficiency of more than 75%. The
potential of the material for holographic data storage applications is also studied using peristrophic
multiplexing
A simple approach for accurate
determination of the resonant frequencies of
microstrip antennas of regular geometries is
developed and presented. In this approach, a
generalised empirical formula for the
computation of effective dielectric permittivity is
given which takes into account the ratio of the
fringing area to the area of the patch. A
correction to the equivalent side length of an
equilateral triangular patch, previously published,
is modified and a new formula is given. A
correction to the effective dimensions of an
elliptical microstrip antenna is also carried out.
Numerical results obtained for the resonant
frequencies of elliptical, circular, rectangular and
equilateral-triangular microstrip antennas are in
good agreement with the available theoretical and
experimental results reported by others. The
present approach is more efficient, simpler and
more accurate
Description:
IEE Proc.-Microw. Antennas Propag., Vol. 145, No. 2, April 1998
Bright Singh, I S; PhIlip, R(Blackwell Publishing, March 1, 1995)
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Abstract:
Larvae of Macrobrachium rosenbergii (De Man) are
photopositive (Ling 1969a.b) and negatively rheotactic.
While investigating larval diseases of M, rosenbergii
it was observed that weak larvae failed to show both
these responses. It was felt that this lack of response
could be used to develop a device for separating the
weak larvae from the apparently healthy ones. Such a
device would be a valuable tool for assessing the health
of a batch in terms of the percentage of 'healthy' and
'weak' larvae. What follows is a description and mode
of operation of the 'photo-flow' device developed by
the authors
Biju Kumar, S; Raveendranath, U; Mohanan, P; Mathew, K T; Hajian,M; Ligthart, L P(Microwave and Optical Technology Letters, July 20, 2000)
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Abstract:
A simple and efficient method for determining the complex
permittivity of dielectric materials from both reflected and transmitted signals is presented. It is also novel because the technique is implemented using two pyramidal horns without any focusing mechanisms. The dielectric constant of a noninteractive and distributive (NID) mixture of dielectrics is also determined
Wilson,K J; Vallabhan, C P G(IOP Publishing, 1989)
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Abstract:
A simple and inexpensive linear magnetic field sweep generating system suitable for magnetic resonance experiments is described. The circuit, utilising a modified IC bootstrap configuration, generates field sweep over a wide range of sweep durations with excellent sweep linearity.
Vermeeren,G; Rogier,H; Olyslager,F; Zutter De,D(IEE Electronics letters,UK, September 13, 2001)
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Abstract:
A single-feed rectangular-ring microstrip antenna is proposed for
indoor communication under the Bluetooth protocol. The
dimensions of the antenna together with the location of the feed
point are optimized through field simulations in order to cover the
Bluetooth bandwidth and to avoid linear polarization. The
performance and the efficiency of the antenna are illustrated in a
real indoor environment
James, Kurian; Balakrishnan, K G; Nair, K G(IOP Publishing LTD, August 19, 1992)
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Abstract:
A simple and inexpensive power supply suitable for characteristics
studies of a klystron is described. The circuit is a modified form of the high voltage
adjustable power supply based on LM 317. This provides the necessary cavity and
repeller voltages over a wide range, with good regulation. The system is protected
aa- ainst short circuits and is ideallv suitable for laboratorv, ex.Deri ments with reflex
klystrons.
Santhi, A; Vinu V, Namboodiri; Radhakrishnan, P; Nampoori, V P N(American Institute of Physics, 2006)
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Abstract:
The authors apply the theory of photothermal lens formation and also that of pure optical nonlinearity to account for the phase modulation in a beam as it traverses a nonlinear medium. It is used to simultaneously determine the nonlinear optical refraction and the thermo-optic coefficient. They demonstrate this technique using some metal phthalocyanines dissolved in dimethyl sulfoxide, irradiated by a Q-switched Nd:YAG laser with 10 Hz repetition rate and a pulse width of 8 ns. The mechanism for reverse saturable absorption in these materials is also discussed.
Kannan, Balakrishnan; Bresar, B; Manoj, Changat; Klavzar, S; Kovse, M; Subhamathi, A R(Wiley Subscription Services, Inc., A Wiley Company, September 1, 2010)
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Abstract:
The distance DG(v) of a vertex v in an undirected graph G is the sum of the
distances between v and all other vertices of G. The set of vertices in G with maximum
(minimum) distance is the antimedian (median) set of a graph G. It is proved that for
arbitrary graphs G and J and a positive integer r 2, there exists a connected graph H
such that G is the antimedian and J the median subgraphs of H, respectively, and that
dH(G, J) = r. When both G and J are connected, G and J can in addition be made
convex subgraphs of H.
Hsieh,Gui-Bin; Chen,Ming-Huang; Wong,Kin-Lu Wong(IEE Electronics letters,UK, June 21, 2001)
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Abstract:
A novel technique for obtaining dual-hand circular polarization
(CP) radiation of a single-feed circular microstrip antenna in
proposed and demonstrated. By embedding two pain of arc shaped
slots of proper lengths close to the boundary of a circular
patch, and protruding one of the arc-shaped slots with a narrow
slit, the circular microstrip antenna can perform dual-hand CP
radiation using a single probe feed. Details of the antenna design
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, June 20, 2000)
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Abstract:
A novel dual frequency dual-polarized square microstrip
patch antenna embedded with a slot is presented. The proposed
antenna offers tunability of the frequency ratio between the two
frequencies by adjusting the slot dimensions. This configuration
also provides a size reduction up to -51 and 35% for the two modes
as compared to a square micro strip patch antenna
In this paper, a new directionally adaptive, learning based, single image super resolution method using
multiple direction wavelet transform, called Directionlets is presented. This method uses directionlets to
effectively capture directional features and to extract edge information along different directions of a set of
available high resolution images .This information is used as the training set for super resolving a low
resolution input image and the Directionlet coefficients at finer scales of its high-resolution image are
learned locally from this training set and the inverse Directionlet transform recovers the super-resolved
high resolution image. The simulation results showed that the proposed approach outperforms standard
interpolation techniques like Cubic spline interpolation as well as standard Wavelet-based learning, both
visually and in terms of the mean squared error (mse) values. This method gives good result with aliased
images also.
Description:
International Journal of Artificial Intelligence & Applications (IJAIA), Vol.1, No.4, October 2010
The quantum yields of singlet oxygen production and
lifetimes at the gas–solid interface in silica gel material
are determined. Different photosensitizers (PS) are encapsulated
in parallelepipedic xerogel monoliths (PS-SG). PS were chosen according
to their known photooxidation properties: 9,10-dicyanoanthracene
(DCA), 9,10-anthraquinone (ANT), and a benzophenone
derivative, 4-benzoyl benzoic acid (4BB). These experiments
are mainly based on time-resolved 1O2 phosphorescence detection,
and the obtained FD and tD values are compared with
those of a reference sensitizer for production, 1H-phenalen-1-
one (PN), included in the same xerogel. The trend between their
ability to oxidize organic pollutants in the gas phase and their efficiency
for production is investigated through photooxidation
experiments of a test pollutant dimethylsulfide (DMS). The
FD value is high for DCA-SG relative to the PN reference, whereas
it is slightly lower for 4BB-SG and for ANT-SG. FD is related to
the production of sulfoxide and sulfone as the main oxidation
products for DMS photosensitized oxidation. Additional mechanisms,
leading to C!S bond cleaveage, appear to mainly occur
for the less efficient singlet oxygen sensitizers 4BB-SG and ANTSG.
Litty, Irimpan; Nampoori, V P N; Radhakrishnan, P; Bindu, Krishnan; Deepthy, A(American Institute of Physics, 2008)
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Abstract:
We have investigated the third-order nonlinearity in ZnO nanocolloids with particle sizes in the range 6-18 nm by the z-scan technique. The third-order optical susceptibility χ(3) increases with increasing particle size (R) within the range of our investigations. In the weak confinement regime, an R2 dependence of χ(3) is obtained for ZnO nanocolloids. The optical limiting response is also studied against particle size.
Litty, Irimpan; Nampoori, V P N; Radhakrishnan, P; Deepthy, A; Bindu, Krishnan(American Institute of Physics, 2007)
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Abstract:
In this article we present size dependent spectroscopic observations of nanocolloids of ZnO. ZnO is reported to show two emission bands, an ultraviolet (UV) emission band and another in the green region. Apart from the known band gap 380 nm and impurity 530 nm emissions, we have found some peculiar features in the fluorescence spectra that are consistent with the nanoparticle size distribution. Results show that additional emissions at 420 and 490 nm are developed with particle size. The origin of the visible band emission is discussed. The mechanism of the luminescence suggests that UV luminescence of ZnO colloid is related to the transition from conduction band edge to valence band, and visible luminescence is caused by the transition from deep donor level to valence band due to oxygen vacancies and by the transition from conduction band to deep acceptor level due to impurities and defect states. A correlation analysis between the particle size and spectroscopic observations is also discussed.
Anantharaman, M R; Manoj, Raama Varma; Al-Harthi, S H; Muhammad, Abdul Jamal E; Senoy, Thomas; Saritha, Nair K(IOP Publishing LTD, January 31, 2008)
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Abstract:
Silver silica nanocomposites were obtained by the sol–gel technique using tetraethyl
orthosilicate (TEOS) and silver nitrate (AgNO3) as precursors. The silver nitrate concentration
was varied for obtaining composites with different nanoparticle sizes. The structural and
microstructural properties were determined by x-ray diffractometry (XRD), Fourier transform
infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). X-ray
photoelectron spectroscopic (XPS) studies were done for determining the chemical states of
silver in the silica matrix. For the lowest AgNO3 concentration, monodispersed and spherical
Ag crystallites, with an average diameter of 5 nm, were obtained. Grain growth and an increase
in size distribution was observed for higher concentrations. The occurrence of surface plasmon
resonance (SPR) bands and their evolution in the size range 5–10 nm is studied. For decreasing
nanoparticle size, a redshift and broadening of the plasmon-related absorption peak was
observed. The observed redshift and broadening of the SPR band was explained using modified
Mie scattering theory
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave Engineering Group,Department of Electronics, January 5, 2002)
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Abstract:
A novel dual frequency design of a square microstrip antenna coaxially
fed along the diagonal with a chip capacitor mounted at the bottom of
the stub is introduced. This design provides enhanced area reduction and
good cross-polarization levels. The antenna design can be used as a compact
antenna system where limited size is a major requirement. The details of the
antenna design and experimental results are presented
Mridula, S; Deepu, V; Sujith, R; Mohanan, P(Wiley Subscription Services, Inc., A Wiley Company, July 18, 2008)
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Abstract:
A slot line fed planar dipole antenna with a parasitic
strip for wide band applications is presented. The presented antenna
offers a 2:1 VSWR bandwidth from 1.66 to 2.71 GHz covering the DCS/
PCS/UMTS and IEEE 802.11b/g bands with a gain better than 6.5 dBi.
The uniplanar design, simple feeding, and high gain make it a versatile
antenna for wireless applications
Description:
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 3, March 2009