Gopikakumari, R; Dr.Sreedhar, C S(Cochin University Of Science And Technology, July 31, 1998)
[+]
[-]
Abstract:
This thesis is an outcome of the investigations carried out on the development of an
Artificial Neural Network (ANN) model to implement 2-D DFT at high speed. A new
definition of 2-D DFT relation is presented. This new definition enables DFT computation
organized in stages involving only real addition except at the final stage of computation. The
number of stages is always fixed at 4. Two different strategies are proposed. 1) A visual
representation of 2-D DFT coefficients. 2) A neural network approach.
The visual representation scheme can be used to compute, analyze and manipulate 2D
signals such as images in the frequency domain in terms of symbols derived from 2x2
DFT. This, in turn, can be represented in terms of real data. This approach can help analyze
signals in the frequency domain even without computing the DFT coefficients.
A hierarchical neural network model is developed to implement 2-D DFT. Presently,
this model is capable of implementing 2-D DFT for a particular order N such that ((N))4 = 2.
The model can be developed into one that can implement the 2-D DFT for any order N upto a
set maximum limited by the hardware constraints. The reported method shows a potential in
implementing the 2-D DF T in hardware as a VLSI / ASIC
Description:
Department of Electronics,
Cochin University of Science and Technology
Prafulla, V; Dr.Lakshmanan, P T(Central Institute of Fisheries Technology, 2002)
[+]
[-]
Abstract:
The present study entitled "Investigations on the Distribution Characteristics of Heavy Metals in Squid (Loligo spp.) in Relation to Levels in Food Fishes from the West Coast of India with a Perspective on Seafood Safety"attempts to
establish the base line data on metal levels in squids along the west
coast of India. The study is of great relevance in the present context
when utmost importance is being given for producing wholesome
seafoods especially in the export market with a perspective on seafood
safety.The thesis presents a comprehensive account of the base line
data on important heavy metals, viz., Hg, Cd, Pb, Cu, Zn, Fe, Mn Cr
and Ni in the edible and non-edible body components of the most
abundant Loligo species, viz., L. duvauceli caught along the west
coast of India.
Krishnan Nair, P R; Nandakumaran, V M(Cochin University of Science and Technology, October , 1999)
[+]
[-]
Abstract:
This thesis is a study of discrete nonlinear systems represented by one dimensional mappings.As one dimensional interative maps represent Poincarre sections of higher dimensional flows,they offer a convenient means to understand the dynamical evolution of many physical systems.It highlighting the basic ideas of deterministic chaos.Qualitative and quantitative measures for the detection and characterization of chaos in nonlinear systems are discussed.Some simple mathematical models exhibiting chaos are presented.The bifurcation scenario and the possible routes to chaos are explained.It present the results of the numerical computational of the Lyapunov exponents (λ) of one dimensional maps.This thesis focuses on the results obtained by our investigations on combinations maps,scaling behaviour of the Lyapunov characteristic exponents of one dimensional maps and the nature of bifurcations in a discontinous logistic map.It gives a review of the major routes to chaos in dissipative systems,namely, Period-doubling ,Intermittency and Crises.This study gives a theoretical understanding of the route to chaos in discontinous systems.A detailed analysis of the dynamics of a discontinous logistic map is carried out, both analytically and numerically ,to understand the route it follows to chaos.The present analysis deals only with the case of the discontinuity parameter applied to the right half of the interval of mapping.A detailed analysis for the n –furcations of various periodicities can be made and a more general theory for the map with discontinuities applied at different positions can be on a similar footing
Nandini Menon,N; Dr.Ravindranatha Menon,N(Cochin University of Science & Technology, April , 1997)
[+]
[-]
Abstract:
The thesis deals with different aspects connected with the distribution and toxicity of PHC in crude oils in the aquatic environment and marine molluscs. Information has been gathered and presented on the present status of research in the field based on a thorough review of recent literature. It is seen from the literature that the resident time of PHC becomes lesser and lesser when crude oil is discharged in large quantities into the coastal waters where excess oxygenation light penetration, temperature availability and strong tidal currents persist. This results in the reduction of the onslaught of oil pollution. This probably shows that taxic insult of crude oil in tropical shores will be relatively lesser than that occurring in temperate and boreal waters. However, there is no record of major episodal oil pollution comparable in quantum and extent to that of Torrey Canyon or Amoco Cadiz which prevents a more reliable analysis on the issue. Considerable controversy exists on the method of estimation of PHC in seawater. However, Ultra-violet fluorescence spectroscopy has been widely recommended as an analytical tool for the determination of total hydrocarbons. Similarly representation of values as chrysene equivalents has been recognised as the most reliable method of Quantum representation.
Description:
Division of Marine Biology, Microbiology and Biochemistry, school of Marine Sciences, Cochin University of Science and Technology
Anantharaman, M R; Saravanan, S; Joseph, Mathai C; Venkitachalam, S; Prabhakaran, P V(Elsevier, January 11, 2006)
[+]
[-]
Abstract:
Polyaniline is chemically synthesised and doped with camphor sulphonic acid. FTIR studies carried out on these samples indicate that
the aromatic rings are retained after polymerisation. The percentage of crystallinity for polyaniline doped with camphor sulphonic acid
has been estimated from the X-ray diffraction studies and is around 56% with respect to polyaniline emeraldine base. The change in
dielectric permittivity with respect to temperature and frequency is explained on the basis of interfacial polarisation. AC conductivity is
evaluated from the observed dielectric permittivity. The values of AC and DC conductivity and activation energy are calculated. The
activation energy values suggested that the hopping conduction is the prominent conduction mechanism in this system.
Description:
Journal of Physics and Chemistry of Solids 67 (2006) 1496–1501
Nirmala, Paul; Dr.Krishna Pillai, M G(Cochin University Of Science And Technology, December 2, 1981)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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