Rejeesh C, John; Dr. Asha, Gopalakrishnan(Cochin University of Science & Technology, February , 2011)
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Abstract:
In this thesis, the concept of reversed lack of memory property and its generalizations
is studied.We we generalize this property which involves operations different
than the ”addition”. In particular an associative, binary operator ” * ” is considered. The
univariate reversed lack of memory property is generalized using the binary operator
and a class of probability distributions which include Type 3 extreme value, power
function, reflected Weibull and negative Pareto distributions are characterized (Asha
and Rejeesh (2009)). We also define the almost reversed lack of memory property
and considered the distributions with reversed periodic hazard rate under the binary
operation. Further, we give a bivariate extension of the generalized reversed lack of
memory property and characterize a class of bivariate distributions which include the
characterized extension (CE) model of Roy (2002a) apart from the bivariate reflected
Weibull and power function distributions. We proved the equality of local proportionality
of the reversed hazard rate and generalized reversed lack of memory property. Study of uncertainty is a subject of interest common to reliability, survival analysis,
actuary, economics, business and many other fields. However, in many realistic
situations, uncertainty is not necessarily related to the future but can also refer to the
past. Recently, Di Crescenzo and Longobardi (2009) introduced a new measure of information
called dynamic cumulative entropy. Dynamic cumulative entropy is suitable
to measure information when uncertainty is related to the past, a dual concept of the
cumulative residual entropy which relates to uncertainty of the future lifetime of a system.
We redefine this measure in the whole real line and study its properties. We also
discuss the implications of generalized reversed lack of memory property on dynamic
cumulative entropy and past entropy.In this study, we extend the idea of reversed lack of memory property to the
discrete set up. Here we investigate the discrete class of distributions characterized by
the discrete reversed lack of memory property. The concept is extended to the bivariate
case and bivariate distributions characterized by this property are also presented. The
implication of this property on discrete reversed hazard rate, mean past life, and discrete past entropy are also investigated.
Description:
Department of Statistics,
Cochin University of Science and Technology
Raji, George; Dr.Jhonson, T P(Cochin University of Science And Technology, September 4, 2013)
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Abstract:
The thesis is divided into nine chapters including introduction.
Mainly
we determine ultra L-topologies in the lattice of L- topologies and
study their properties.
We nd some sublattices in the lattice of L-topologies and study
their properties.
Also we study the lattice structure of the set of all L-closure operators
on a set X.
Description:
Department of Mathematics
Cochin University of Science and Technology
Rajeswari Devi, M B; Dr.Jathavedan, M(Cochin University of Science and Technology, December , 2006)
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Abstract:
In this thesis an attempt is made to study vortex knots based on the work of
Keener . It is seen that certain mistakes have been crept in to the details of this
paper. We have chosen this study for an investigation as it is the first attempt to
study vortex knots. Other works had given attention to this. In chapter 2 we have
considered these corrections in detail. In chapter 3 we have tried a simple extension by introducing vorticity in the evolution of vortex knots. In chapter 4 we have introduced
a stress tensor related to vorticity. Chapter 5 is the general conclusion.Knot theory is a branch of topology and has been developed as an independent
branch of study. It has wide applications and vortex knot is one of them. As pointed
out earlier, most of the studies in fluid dynamics exploits the analogy between vorticity
and magnetic induction in the case of MHD. But vorticity is more general than magnetic
induction and so it is essential to discuss the special properties of vortex knots,
independent of MHD flows. This is what is being done in this thesis.
Description:
Dept.of Mathematics,
Cochin University of Science and Technology
Yoosaf, K; Dr. George Thomas, K(Chemical Sciences and Technology Division,CSIR, January , 2008)
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Abstract:
Most of the procedures reported for the synthesis of metal
nanoparticles involve the use of strong reducing agents or elevated
temperatures. This limits the possibility of developing metal nanoparticle
based sensors for the in situ detection of analytes. One of the objectives of
the present investigations is to (i) develop newer methodologies for the
synthesis of metal nanoparticles in aqueous medium at ambient conditions
and (ii) their use in the detection of metal cations by taking advantage of
the unique coordination ability. Ideally, biocompatible molecules which
possess both the reducing and stabilizing groups are desirable for such
applications. Formation of stable supramolecular assembly, by bringing metal nanoparticles close to each other, results in plasmon coupling and
this strategy can be effectively utilized for the development of metal
nanoparticle based sensors.Another objective of the present study is to understand the
supramolecular organization of molecules on surfaces. Various
noncovalent interactions between the molecules and with surface play a
decisive role in their organizations. An in-depth understanding of these
interactions is essential for device fabrications. Recent photophysical
studies have revealed that phenyleneethynylene based molecular systems
are ideal for device application. The second objective of the thesis focuses
on understanding the (i) organization of phenyleneethynylenes on highly
oriented pyrolytic graphite (HOPG) surface with atomic level precision and
(ii) weak intermolecular interactions which drive their organization.
Jalaja, Malayan J; Dr.Sugunan, S(Cochin University of Science and Technology, December , 1994)
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Abstract:
The rare earths have provided fascinating field
for chemists confronted with problems of their separation
and purification. The rare earths become available in
relatively pure form in recent years due to the development
of efficient separation methods, largely as a byproduct of
the atomic energy programmes of various countries. The
rare earths often called lanthanides from La (Z=57) to Lu
(Z=7l) display subtle variation of properties through the
series, while the differences become appreciable for the
elements that are farther apart.
Description:
Department of
Applied Chemistry, Cochin University of Science and
Technology
Ramankutty, C G; Dr.Sugunan, S(Cochin University of Science & Technology, November , 2000)
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Abstract:
The present study describes the surface properties and catalytic activities of
ferrospinels containing Co, Ni and Cu prepared by the low temperature route. Various
physico-chemical methods have been adopted to characterise the systems. The reactions
carried out are the Friedel-Crafts benzoylation of aromatics and the cyclohexanol
decomposition. We have attempted the sulphate modification of the ferrites and have
studied the surface and catalytic properties of the sulphated analogues.The work is presented in six chapters, the last chapter giving the summary and
conclusions of the results presented earlier. Our samples prove as potential catalysts for
the benzoylation of aromatics , for which truly heterogeneous catalysts are rare. Again ,
the materials show remarkable dehydration/dehydrogenation activities during
cyclohexanol decomposition. There is plenty of scope for research in this field, especially
in the development of environmentally benign catalysts for acylation reactions.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Nishamol,Kanat; Sugunan, S(Department of applied chemistry, 2002)
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Abstract:
In recent years considerable advances have been achieved in the study of the surface structure and mechanism of action of environmentally benign heterogeneous catalysts. The study entitled as surface properties and catalytic activity of manganese ferrospinels. In the present study we have prepared manganese ferrospinels of general formula Mn(1-x)BxFe2O4 via low temperature controlled co-precipation method. The study employed low temperature co-precipitation method for the preparation ofMn(1-x)BxFe2O4 specimens, where B is a metal cation such as Cr,Co, Ni,Cu and Zn. The catalytic activities of the systems were investigated for liquid-phase benzoylation of aromatic compounds and phenol hydroxylation and for vapour-phase reactions such as aniline alkylation, phenol methylation and ODH of ethylbenzene. The different series of manganese ferrites are proved to be excellent catalysts for various industrially important reactions such as Friedel-crafts benzoylation of aromatic compounds, methylation of aniline and phenol, hydroxylation of phenol and oxidative dehydrogenation of ethylbenzene. Due to the tightening of the environmental regulations, production of diphenols from phenol hydroxylation and reduction of phenolic pollutants in waste waters using these catalysts can be a promising approach because it demands only simple techniques and produce little environmental pollution.
Renuka, N K; Dr.Sugunan, S(Cochin University of Science & Technology, November , 2000)
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Abstract:
An investigation on the physical and chemical characterisation of rare earth oxide
supported vanadia is attempted in the present study. La2O3, Sm2O3 and DY2O3 serve the
purpose of supports. Supported catalysts were prepared and characterised using various
physico chemical techniques. A detailed investigation of acid base properties is also
carried out. The nature of interaction of vanadia with lanthanide oxide is discussed and
the effect of vanadia loading on the activity of the systems towards reactions of industrial
importance is explored.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Vijayakumar, K P; Dr.Purushothaman, C(Cochin University of Science and Technology, May 28, 1984)
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Abstract:
The thesis aims to present the results of experimental investigations on the changes of optical properties of metallic thin films due to heating. The parameters which are measured are reflectivity, refractive indices and the ellipsometric quantities V and A . The materials used in the studies are metals like Silver, Aluminium and Copper. By applying the optical method the interdiffusion taking place in multilayer
‘films of Aluminium and Silver has also been studied. Special interest has been taken to reveal the mechanisms of the hillock growth and surface roughness caused by heating and their relation with the stress in the film
Description:
Department of Physics, Cochin University of Science and Technology
Raghavan, Lisha; Prof. (Dr.) M. R. Anantharaman(Cochin University of Science and Technology, August 9, 2015)
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Abstract:
Magnetism and magnetic materials have been playing a lead role in the day to day life of human beings. The human kind owes its gratitude to the ‘lodestone’ meaning ‘leading stone’ which lead to the discovery of nations and the onset of modern civilizations. If it was William Gilbert, who first stated that ‘earth was a giant magnet’, then it was the turn of Faraday who correlated electricity and magnetism. Magnetic materials find innumerable applications in the form of inductors, read and write heads, motors, storage devices, magnetic resonance imaging and fusion reactors. Now the industry of magnetic materials has almost surpassed the semiconductor industry and this speaks volumes about its importance. Extensive research is being carried out by scientists and engineers to remove obsolescence and invent new devices. Though magnetism can be categorized based on the response of an applied magnetic field in to diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic; it is ferrimagnetic, ferromagnetic and antiferromagnetic materials which have potential applications. The present thesis focusses on these materials, their composite structures and different ways and means to modify their properties for useful applications.
Lisha, Raghavan; Dr M. R. Anantharaman(Cochin University of Science and Technology, June 30, 2016)
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Abstract:
Magnetism and magnetic materials have been playing a lead role in the day to day life of human beings. The human kind owes its gratitude to the ‘lodestone’ meaning ‘leading stone’ which lead to the discovery of nations and the onset of modern civilizations. If it was William Gilbert, who first stated that ‘earth was a giant magnet’, then it was the turn of Faraday who correlated electricity and magnetism. Magnetic materials find innumerable applications in the form of inductors, read and write heads, motors, storage devices, magnetic resonance imaging and fusion reactors. Now the industry of magnetic materials has almost surpassed the semiconductor industry and this speaks volumes about its importance. Extensive research is being carried out by scientists and engineers to remove obsolescence and invent new devices. Though magnetism can be categorized based on the response of an applied magnetic field in to diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic; it is ferrimagnetic, ferromagnetic and antiferromagnetic materials which have potential applications. The present thesis focusses on these materials, their composite structures and different ways and means to modify their properties for useful applications.
In the past, metals like Fe, Ni and Co were sought after for various applications though iron was in the forefront because of its cost effectiveness and abundance. Later, alloys based on Fe and Ni were increasingly employed. They were used in magnetic heads and in inductors. Ferrites entered the arena and subsequently most of the newer applications were based on ferrites, a ferrimagnetic material, whose composition can be tuned to tailor the magnetic properties. In the late 1950s a new class of magnetic material emerged on the magnetic horizon and they were fondly known as metallic glasses. They are well known for their soft magnetic properties. They were synthesized in the form of melt spun ribbons and are amorphous in nature and they are projected to replace the crystalline counterparts.
Arun,V; Dr.Mohammed Yusuff,K K(Cochin University of Science & Technology, June , 2009)
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Abstract:
The thesis deals with studies on the synthesis, characterisation and catalytic
applications of some new transition metal complexes of the Schiff bases derived from 3-hydroxyquinoxaline 2-carboxaldehyde.. Schiff bases which are considered as ‘privileged ligands’ have the ability to stabilize different metals in different oxidation states and thus regulate the performance of metals in a large variety of catalytic transformations. The
catalytic activity of the Schiff base complexes is highly dependant on the environment about
the metal center and their conformational flexibility. Therefore it is to be expected that the
introduction of bulky substituents near the coordination sites might lead to low symmetry complexes with enhanced catalytic properties. With this view new transition metal
complexes of Schiff bases derived from 3-hydroxyquinoxaline-2-carboxaldehyde have been
synthesised. These Schiff bases have more basic donor nitrogen atoms and the presence of
the quinoxaline ring may be presumed to build a favourable topography and electronic
environment in the immediate coordination sphere of the metal. The aldehyde was condensed
with amines 1,8-diaminonaphthalene, 2,3-diaminomaleonitrile, 1,2-diaminocyclohexane,
2-aminophenol and 4-aminoantipyrine to give the respective Schiff bases. The oxovanadium(IV), copper(II) and ruthenium(II)complexes of these Schiff bases were synthesised and characterised.
All the oxovanadium(IV) complexes have binuclear structure with a square pyramidal geometry.
Ruthenium and copper form mononuclear complexes with the Schiff base derived from 4-
aminoantipyrine while binuclear square planar complexes are formed with the other Schiff
bases. The catalytic activity of the copper complexes was evaluated in the hydroxylation of
phenol with hydrogen peroxide as oxidant. Catechol and hydroquinone are the major products. Catalytic properties of the oxovanadium(IV) complexes were evaluated in the
oxidation of cyclohexene with hydrogen peroxide as the oxidant. Here allylic oxidation
products rather than epoxides are formed as the major products. The ruthenium(II)
complexes are found to be effective catalysts for the hydrogenation of benzene and toluene.
The kinetics of hydrogenation was studied and a suitable mechanism has been proposed.
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology