Issac, R C; Varier, G K; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Springer, 1998)
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Abstract:
The dynamics of diffusion of electrons and ions from the laser-produced plasma from a multielement superconducting material, namely YBa2Cu3O7, using a Q-switched Nd:YAG laser is investigated by time-resolved emission-spectroscopic techniques at various laser irradiances. It is observed that beyond a laser irradiance of 2.6 \xC3\x97 1011 W cm-2, the ejected plume collectively drifts away from the target with a sharp increase in velocity to 1.25 \xC3\x97 106 cm s-1, which is twice its velocity observed at lower laser irradiances. This sudden drift apparently occurs as a result of the formation of a charged double layer at the external plume boundary. This diffusion is collective, that is, the electrons and ions inside the plume diffuse together simultaneously and hence it is similar to the ambipolar diffusion of charged particles in a discharge plasma
Anantharaman, M R; Sagar, S; Ganesan, V; Joy, P A; Senoy, Thomas; Liebig, A; Albrecht, M(IOP Publishing LTD, July 30, 2010)
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Abstract:
Manganites belonging to the series Gd1−xSrxMnO3 (x=0.3, 0.4 and 0.5) were
prepared by wet solid-state reaction and their thermoelectric power was evaluated. Thermoelectric
power measurements revealed a peak value at ∼40 K. All the samples exhibited a colossal
thermopower at ∼40K and in that Gd0.5Sr0.5MnO3 exhibited a maximum value of ∼35mV/K,
which is the largest reported for these class of materials at this temperature. Temperaturedependent
magnetisation measurements showed that the samples exhibit a phase transition from
paramagnetic to spin-glass–like state at these temperatures. Plausible mechanisms responsible for
the observed colossal thermoelectric power in Gd-Sr manganites are discussed
Xiong,X Z; Fusco,V F(Microwave and Optical Technology Letters, August 5, 2002)
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Abstract:
In this Letter a new physical model for metal-insulatormetal
CMOS capacitors is presented. In the model the parameters of the
circuit are derived from the physical structural details. Physical behaviors
due to metal skin effect and inductance have been considered. The
model has been confirmed by 3D EM simulator and design rules proposed.
The model presented is scalable with capacitor geometry, allowing
designers to predict and optimize quality factor. The approach has
been verified for MIM CMOS capacitors
Poulose Jacob,K; Sonia, Sunny; David, Peter S(Computer Science, 2013)
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Abstract:
Speech processing and consequent recognition are important areas of Digital Signal Processing
since speech allows people to communicate more natu-rally and efficiently. In this work, a
speech recognition system is developed for re-cognizing digits in Malayalam. For recognizing
speech, features are to be ex-tracted from speech and hence feature extraction method plays an
important role in speech recognition. Here, front end processing for extracting the features is
per-formed using two wavelet based methods namely Discrete Wavelet Transforms (DWT) and
Wavelet Packet Decomposition (WPD). Naive Bayes classifier is used for classification purpose.
After classification using Naive Bayes classifier, DWT produced a recognition accuracy of
83.5% and WPD produced an accuracy of 80.7%. This paper is intended to devise a new
feature extraction method which produces improvements in the recognition accuracy. So, a new
method called Dis-crete Wavelet Packet Decomposition (DWPD) is introduced which utilizes
the hy-brid features of both DWT and WPD. The performance of this new approach is evaluated
and it produced an improved recognition accuracy of 86.2% along with Naive Bayes classifier.
Description:
Computer Science & Information Technology (CS & IT)
Rohith, Raj K; Sona,Kundukulam O; Aanandan,C K; Vasudevan, K; Mohanan, P; Praveen,Kumar(Microwave and Optical Technology Letters, February 20, 2004)
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Abstract:
compact microstrip antenna integrated with an amplifier
having an area reduction of 70%, compared to the standard circular microstrip
patch antenna, is presented. The antenna also provides an enhanced
gain of 10-dB more than its passive counter part. The measured 2:1
VSWR band width is -4% at 790 MHz, which is 2.5 times larger than that
of the passive microstrip antenna
An asymmetric coplanar strip-fed uniplanar antenna for wideband applications is presented. The resulting antenna offers a 2:1 VSWR bandwidth greater than 100% from 1.58 to 5.48 GHz covering the DCS/PCS/IEEE 802.11a/WiMAX bands. The antenna has an overall dimension of 44 × 35 mm2 when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The design equation is also presented in this article. The antenna exhibits good radiation characteristics and moderate gain in the entire operating band.
The design and implementation of a novel asymmetric coplanar
waveguide (ACPW ) band rejection filter using defected ground
structure ( DGS) is presented . The proposed ACPW DGS technology
provides band gap characteristics with only one cell in the lateral
ground plane . The equivalent circuit model of the proposed DGS
unit section is described . Measurements of ACPW DGS showed good
agreement with simulation and the proposed model
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, August 5, 2002)
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Abstract:
Development of a new compact circular-sided microstrip
antenna is presented. This antenna offers considerable area re- TABLE 2. Variation of Resonant Frequencies
duction compared to standard rectangular microstrip antenna designed
for the same frequency. Typical antenna design and
experimental results for circular polarization are also demonstrated.
77je antenna has a 3-dB axial ratio bandwidth of 1.5%
A compact Co-Planar Waveguide (CPW) fed antenna operating at 2.4GHz with 300MHz 2:1 VSWR
bandwidth is presented. Compared to a conventional quarter wavelength CPW fed monopole antenna, the aperture
area reduction of the present antenna is 85%. The prototype antenna fabricated on a substrate of εr = 4.4 and
thickness 1.6mm is only 22x10x1.6mm3. This much size reduction and impedance matching is achieved by
adjusting the signal to ground plane separation and meandering the ground plane of a 50Ω CPW transmission line
Description:
General Assembly and Scientific Symposium, 2011 XXXth URSI
Mridula, S; Shameena, V A; Anju, Pradeep; Sarah, Jacob; Lindo, A O; Mohanan, P(Elsevier, March 20, 2011)
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Abstract:
A printed compact coplanar waveguide fed triangular slot antenna for ultra wide band (UWB) communication
systems is presented. The antenna comprises of a triangular slot loaded ground plane with a T
shaped strip radiator to enhance the bandwidth and radiation. This compact antenna has a dimension
of 26mm×26mm when printed on a substrate of dielectric constant 4.4 and thickness 1.6mm. Design
equations are implemented and validated for different substrates. The pulse distortion is insignificant
and is verified by the measured antenna performance with high signal fidelity and virtually steady group
delay. The simulation and experiment reveal that the proposed antenna exhibits good impedance match,
stable radiation patterns and constant gain and group delay over the entire operating band
A compact coplanar waveguide (CPW)-fed uniplanar antenna with harmonic
suppression characteristics is presented. The above characteristics are achieved by properly
modifying the ground plane and adjusting the signal strip of an open-ended CPW-fed transmission
line. The simulated and experimental characteristics of the antenna are presented, compared,
and discussed.
Description:
International Journal of RF and Microwave Computer‐Aided Engineering,vol 21,issue 5,pp 543-550
A compact coplanar waveguide (CPW) fed uniplanar antenna for Quad-band applications is presented.
The Quad-band operation is realized by imposing various current paths in a modified T-shaped radiating
element. The antenna covers GSM 900, DCS 1800, IEEE802.11.a, IEEE802.11.b and HiperLAN-2 bands and
exhibits good radiation characteristics. This low profile antenna has a dimension of 32mm×31mmwhen
printed on a substrate of dielectric constant 4.4 and height 1.6mm. Details of design with experimental
and simulated results are presented
Gijo,Augustin; Shynu, S V; Mohanan, P; Aanandan,C K; Vasudevan, K(Electronics Letters, April 27, 2006)
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Abstract:
A compact dual-band printed antenna covering the 2.4 GHz (2400-2485 MHz) and 5.2 GHz (5150-5350 MHz) WLAN bands is presented. The experimental analysis shows a 2:1 VSWR bandwidth of up to 32 and 8% for 2.4 and 5.2 GHz, respectively. The measured radiation patterns are nearly omnidirectional, with moderate gain in both the WLAN bands.
A compact, dual band coplanar waveguide fed modified T-shaped uniplanar antenna is presented. The antenna has resonances at 1.77 and 5.54 GHz with a wide band from 1.47–1.97 GHz and from 5.13–6.48 GHz with an impedance bandwidth of 34% and 26%, respectively. Also the antenna has an average gain of 3 dBi in lower band and 3.5 dBi in higher band with an average efficiency of 90%.
Design of a compact dual frequency microstrip antenna
is presented. The structure consists of a slotted circular patch with
a dielectric superstrate. The superstrate,not only acts as a radome,
but improves the bandwidth and lowers the resonant frequency also.
The proposed design provides an overall size reduction of about 60%
compared to an unslotted patch along with good efficiency,gain
and bandwidth. The polarization planes at the two resonances are
orthogonal and can be simultaneously excited using a coaxial feed.
Parametric study of this configuration showed that the frequency ratio
of the two resonances can be varied from 1.17 to 1.7 enabling its
applications in the major wireless communication bands like AWS,
DECT,PHS,Wi.Bro, ISM,and DMB. Design equations are also
deduced for the proposed antenna and validated.
Deepti Das, Krishna; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(Electronics Letters, August 3, 2006)
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Abstract:
Design of a dual linearly-polarised microstrip patch antenna, excited
by two orthogonal microstrip feed lines, is presented. A reduction in
patch size of 35% is obtained when compared to a square patch
operating at the same frequency. The polarisations are oriented at +45
and - 45 with an isolation of more than 36 dB between the ports.
Unlike earlier designs, the proposed structure provides better gain.
Aanandan,C K; Mohanan, P; Vasudevan, K; Shynu, S V; Gijo,Augustin(Department of Electronics, 2004)
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Abstract:
A novel design of a computer electronically reconfigurable dual frequency dual polarized single feed hexagonal slot loaded microstrip antenna in L-band is introduced in this chapter. pin diodes are used to switch the operating frequencies considerably without much affecting the radiation characteristics and gain. the antenna can work with a frequency ratio varying in the wide range from 1.2 to 1.4. the proposed design has an added advantage of size reduction up to 72.21% and 46.84% for the two resonating frequencies compared to standard rectangular patches. the design also gives considerable bandwidth of up to 2.82% and 2.42 % for the operating frequencies.
Manju,Paulson; Sona,Kundukulam O; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, October 28, 2002)
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Abstract:
An arrow-shaped microstrip antenna with a pair of narrow
slots embedded near the non-radiating edges gives wide impedance bandwidth.
The experimental and simulated (!E3D) results show that antenna
bandwidth is -3.5 times that of a conventional patch with the added advantage
of reduced antenna size. The radiation characteristics are found to he uniform throughout the operating band
Mridula, S; Shameena, V A; Aanandan,C K; Mohanan, P; Vasudevan, K; Jacob, S(IEEE, September , 2011)
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Abstract:
A Coplanar waveguide fed compact planar
monopole antenna with a modified ground plane is presented.
Measured and simulated results reveal that the antenna operates
in the Ultra Wide Band with almost constant group delay
throughout the band. Developed design equations of the antenna
are validated for different substrates. Time domain performance
of the antenna is also discussed in order to assess its suitability
for impulse radio applications
Description:
General Assembly and Scientific Symposium, 2011 XXXth URSI