Nirmala, Paul; Dr.Krishna Pillai, M G(Cochin University Of Science And Technology, December 2, 1981)
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Abstract:
The thesis is a report of the attempts made to
prepare semiconducting and dielectric thin films and to
study their electrical properties. It consists of (i)
studies on the preparation and electrical characteristics
of compound semiconductor thin films of silver sulphide
and ferric hydroxide, and (ii) investigations on the electrical
and dielectric properties of plasma polymerized
thin films of para-toluidine element
Description:
Department
of Physics,Cochin University Of Science And Technology
Matlrew, George; Dr.Anantharaman, M R(Cochin University of Science & Technology, February , 2004)
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Abstract:
Magnetism and magnetic materials have been an ever-attractive
subject area for engineers and scientists alike because of its versatility in
finding applications in useful devices. They find applications in a host of
devices ranging from rudimentary devices like loud speakers to sophisticated
gadgets like waveguides and Magnetic Random Access Memories (MRAM).The one and only material in the realm of magnetism that has been at the
centre stage of applications is ferrites and in that spinel ferrites received the
lions share as far as practical applications are concerned.It has been the endeavour of scientists and engineers to remove
obsolescence and improve upon the existing so as to save energy and
integrate in to various other systems. This has been the hallmark of material
scientists and this has led to new materials and new technologies.In the field of ferrites too there has been considerable interest to
devise new materials based on iron oxides and other compounds. This means
synthesising ultra fine particles and tuning its properties to device new
materials. There are various preparation techniques ranging from top- down
to bottom-up approaches. This includes synthesising at molecular level, self
assembling,gas based condensation. Iow temperature eo-precipitation, solgel
process and high energy ball milling. Among these methods sol-gel
process allows good control of the properties of ceramic materials. The
advantage of this method includes processing at low temperature. mixing at
the molecular level and fabrication of novel materials for various devices.Composites are materials. which combine the good qualities of one
or more components. They can be prepared in situ or by mechanical means
by the incorporation of fine particles in appropriate matrixes. The size of the
magnetic powders as well as the nature of matrix affect the processability
and other physical properties of the final product. These plastic/rubber
magnets can in turn be useful for various applications in different devices.
In applications involving ferrites at high frequencies, it is essential that the
material possesses an appropriate dielectric permittivity and suitable
magnetic permeability. This can be achieved by synthesizing rubber ferrite
composites (RFC's). RFCs are very useful materials for microwave
absorptions. Hence the synthesis of ferrites in the nanoregirne.investigations on their size effects on the structural, magnetic, and electrical
properties and the incorporation of these ferrites into polymer matrixes
assume significance.In the present study, nano particles of NiFe204, Li(!5Fe2S04 and
Col-e-O, are prepared by sol gel method. By appropriate heat treatments,
particles of different grain sizes are obtained. The structural, magnetic and
electrical measurements are evaluated as a function of grain size and
temperature. NiFel04 prepared in the ultrafine regime are then incorporated
in nitrile rubber matrix. The incorporation was carried out according to a
specific recipe and for various loadings of magnetic fillers. The cure
characteristics, magnetic properties, electrical properties and mechanical
properties of these elastomer blends are carried out. The electrical
permittivity of all the rubber samples in the X - band are also conducted.
Description:
Department of Physics,
Cochin University of Science & Technology
Mathew, George; Dr.Anantharaman, M R(Cochin University Of Science And Technology, February 16, 2004)
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Abstract:
In the present study, nano particles of NiFe3O4, I_.l()5Feg5O4 and
CoFegO4 are prepared by sol gel method. By appropriate heat treatments,
particles of different grain sizes are obtained. The structural, magnetic and
electrical measurements are evaluated as a function of grain size and
temperature. NiFe3O4 prepared in the ultrafine regime are then incorporated
in nitrile rubber matrix. The incorporation was carried out according to a
specific recipe and for various loadings of magnetic fillers. The cure
characteristics, magnetic properties, electrical properties and mechanical
properties of these elastomer blends are carried out. The electrical
permittivity of all the rubber samples in the X — band are also conducted
Description:
Department of Physics
Cochin University of Science & Technology
Joseph, John; Sajeev, Sivaraman; Jayalekshmy, S; Anantharaman, M R(Elsevier, July , 2010)
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Abstract:
Plasma polymerization is found to be an excellent technique for the preparation of good quality, pinhole-free, polymer thin films from different monomer precursors. The present work describes the preparation and characterization of polypyrrole (PPy) thin films by ac plasma polymerization technique in their pristine and in situ iodine doped forms. The electrical conductivity studies of the aluminiumpolymeraluminium (AlpolymerAl) structures have been carried out and a space charge limited conduction (SCLC) mechanism is identified as the most probable mechanism of carrier transport in these polymer films. The electrical conductivity shows an enhanced value in the iodine doped sample. The reduction of optical band gap by iodine doping is correlated with the observed conductivity results.
Sagar, S; Dr.Anantharaman, M R(Cochin University of Science & Technology, August , 2010)
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Abstract:
This thesis lays importance in the investigation on the multiferroic and
thermooelectric properties of selected representatives of low bandwidth and
intermediate band width manganites. The first candidate, Strontium doped Gd manganite, is prepared by wet solid state reaction method and the second
candidate, Na doped La manganite, by citrate gel method. In addition to the above
mentioned properties, magneto resistance and dielectric properties are
investigated. Using dielectric spectroscopic the dispersion parameters are
correlated to the relaxation mechanisms and an attempt is made to obtain the grain
and grain boundary contribution to the impedance of the sample through
impedance spectroscopy studies.
Description:
Department of Physics,
Cochin University of Science & Technolog
Palson,T I; Dr.Joy, George(Cochin University Of Science And Technology, February 16, 1987)
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Abstract:
The work reported in this thesis is the preparation,
and the structural, electrical and optical properties
of reactively evaporated lead sulphide and tin telluride
thin films. The three temperature method had been used
for the preparation of these semiconductor thin films.
In this preparation technique constituent elements are
evaporated from separate sources with the substrate kept
at a particular temperature. when one of the constituent
element is a gas near room temperature, the method is
often called reactive evaporation. It has been found for
many materials that a stoichiometric interval exists with
a limited range of flux and substrate temperature. Usually
this technique is used for the preparation of thin films of
high melting point compounds or of materials which decompose
during evaporation. Tin telluride and lead sulphide are
neither high melting point materials nor do they decompose
on melting. But even than reactive evaporation offers the
possibility of changing the ratios of the flux of the constituent
elements within a wide range and studying its
effect on the properties of the films
Description:
Department of Physics, Cochin
University of Science and Technology
Sarin, V P; Dr.Vasudevan, K(Cochin University of Science and Technology, January , 2012)
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Abstract:
With the recent progress and rapid increase in mobile terminals, the design of
antennas for small mobile terminals is acquiring great importance. In view of this
situation, several design concepts are already been addressed by the scientists and
engineers. Compactness and efficiency are the major criteria for mobile terminal
antennas. The challenging task of the microwave scientists and engineers is to device
compact printed radiating systems having broadband behavior, together with good
efficiency. Printed antenna technology has received popularity among antenna
scientists after the introduction of microstrip antenna in 1970s. The successors in this
kind such as printed monopoles and planar inverted F are also equally important.
Scientists and Engineers are trying to explore this technology as a viable coast
effective solution for forthcoming microwave revolution. The transmission line
perspectives of antennas are very interesting. The concept behind any
electromagnetic radiator is simple. Any electromagnetic system with a discontinuity
is radiating electromagnetic energy. The size, shape and the orientation of the
discontinuities controls the radiation characteristics of the system such as radiation
pattern, gain, polarization etc. It can be either resonant or non resonant structure.
Microstrip antennas are suitable for wireless applications due to their low cost,
high gain and ease of fabrication. But the major disadvantage of micro strip antennas is
their inherent narrow bandwidth. A lot of techniques are introduced by the researchers
all over the world to enhance the bandwidth of micro strip patch antennas. The thesis
addresses an attempt to enhance the bandwidth of micro strip patch antennas by
incorporating impedance matching strip as a part of the micro strip patch antenna. The
first part of the thesis deals with the broadband operation of the tilted square slot and
polygonal slot loaded square micro strip patch antennas. The resonant mechanisms are
clearly mentioned using the simulation and experimental studies. The bandwidth of the
polygonal slotted broadband patch antenna is again enhanced by implementing an Lstrip
feed mechanism. In the second major part of the thesis, a novel gain enhancement
technique for single band and broadband square micro strip patch antennas is achieved
by implementing offset stacked configurations.
Description:
Department of Electronics
Cochin University of Science and Technology
Sarin, V.P; Dr. K. Vasudevan(Cochin University of Science and Technology, January 14, 2012)
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Abstract:
With the recent progress and rapid increase in mobile terminals, the design of
antennas for small mobile terminals is acquiring great importance. In view of this
situation, several design concepts are already been addressed by the scientists and
engineers. Compactness and efficiency are the major criteria for mobile terminal
antennas. The challenging task of the microwave scientists and engineers is to device
compact printed radiating systems having broadband behavior, together with good
efficiency. Printed antenna technology has received popularity among antenna
scientists after the introduction of microstrip antenna in 1970s. The successors in this
kind such as printed monopoles and planar inverted F are also equally important.
Scientists and Engineers are trying to explore this technology as a viable coast
effective solution for forthcoming microwave revolution. The transmission line
perspectives of antennas are very interesting. The concept behind any
electromagnetic radiator is simple. Any electromagnetic system with a discontinuity
is radiating electromagnetic energy. The size, shape and the orientation of the
discontinuities controls the radiation characteristics of the system such as radiation
pattern, gain, polarization etc. It can be either resonant or non resonant structure.
Vasudevan, K; Dr.Nair, K G(Cochin University of Science and Technology, April 19, 1982)
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Abstract:
Antennas play an important role in determining
the characteristics of any electronic system which depends
on free space as the propagation medium. Basically, an
antenna can be considered as the connecting link between
free space and the transmitter or receiver. For radar and
navigational purposes the directional properties of an
antenna is its most basic requirement as it determines the
distribution of radiated energy. Hence the study of directional properties of antennas has got special significance
and several useful applications.
Description:
Department of Physics, Cochin University of Science and Technology
Joseph, V P; Dr.Mathew, K T(Cochin University of Science And Technology, July , 1999)
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Abstract:
Investigations on the design and development of certain new hollow
dielectric hom antennas of rectangular cross section have been carried out. The main
shortcoming of the existing ordinary hollow dielectric hom antenna (HDH) is the
abrupt discontinuity at the feed-end. A new launching technique using a dielectric rod is
introduced to overcome this limitation. Also a strip loading technique is employed for
further modification of the antenna. Radiation parameters of new I-IDH antennas of Eplane
sectoral, H-plane sectoral and pyramidal types were studied and are found to be
very attractive. Theoretical approach based on Marcatili’s principle and two aperture
theory along with diffraction theory and image theory is used to support the experimental
findings. The HDH is considered as solid horn of effective dielectric constant and the
aperture field is evaluated. The antenna is excited by the open waveguide in the dominant
TE1o mode and so the existence of any hybrid mode is mled-out. The theoretical results
are observed to be in good agreement with the experimental results.
Description:
Department of Electronics, Cochin University of Science and Technology
Gopikrishna, M; Dr.Aanandan, C K(Cochin University of Science & Technology, July , 2010)
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Abstract:
A major challenge in the transmission of narrow pulses is the radiation characteristics
of the antenna. Designing the front ends for UWB systems pose challenges
compared to their narrow and wide band counterparts because in addition to
having electrically small size, high efficiency and band width, the antenna has
to have excellent transient response. The present work deals with the design
of four novel antenna designs- Square Monopole, Semi-Elliptic Slot, Step and
Linear Tapered slot - and an assay on their suitability in UWB Systems. Multiple
resonances in the geometry are matched to UWB by redesigning the ground-patch
interfaces. Techniques to avoid narrow band interference is proposed in the
antenna level and their effect on a nano second pulse have also been investigated.
The thesis proposes design guidelines to design the antenna on laminates of any
permittivity and the analyzes are complete with results in the frequency and time
domains.
Description:
Department of Electronics,
Cochin University of Science and Technology
Jesty, Thomas; Surender, G D; Reddy, M L P(RRL (CSIR), 2000)
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Abstract:
The thesis entitled INVESTIDGATIONS ON THE RECOVERY OF TITANIUM VANADIUM AND IRON VALUES FROM THE WASTE CHILORIDE LIQUORS OF TITANIA INDUSTRY embodies the results of the investigations carried out on the solvent extraction separation of iron (III) vanadium(V) and titanium (IV) chlorides from the waste chloride liquors of titanium minerals processing industry by employing tributylphosphate (TBT) as an extractant. The objective of this study is to generate the knowledge base to achieve the recovery of iron, vanadium and titanium cvalues from multi- metal waste chloride liquors originating from ilmenite mineral beneficiation industries through selective separation and value added material development