Harikrishnan, K P; Dr.Nandakumaran,V M(Cochin University Of Science And Technology, November 3, 1989)
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Abstract:
Nature is full of phenomena which we call
"chaotic", the weather being a prime example.
What we mean by this is that we cannot predict it
to any significant accuracy, either because the
system is inherently complex, or because some of
the governing factors are not deterministic. However,
during recent years it has become clear that
random behaviour can occur even in very simple
systems with very few number of degrees of freedom,
without any need for complexity or indeterminacy.
The discovery that chaos can be generated even with
the help of systems having completely deterministic
rules - often models of natural phenomena - has
stimulated a lo; of research interest recently. Not
that this chaos has no underlying order, but it is
of a subtle kind, that has taken a great deal of
ingenuity to unravel. In the present thesis, the author
introduce a new nonlinear model, a ‘modulated’
logistic map, and analyse it from the view point of
‘deterministic chaos‘.
Description:
Department of Physics, Cochin University of
Science and Technology
Vijayakrishnan,S; Chakravarti,R S; Thrivikraman,T(Department of Mathematics,Faculty OF Science, 2002)
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Abstract:
The present study on some infinite convex invariants. The origin of convexity can be traced back to the period of Archimedes and Euclid. At the turn of the nineteenth centaury , convexicity became an independent branch of mathematics with its own problems, methods and theories. The convexity can be sorted out into two kinds, the first type deals with generalization of particular problems such as separation of convex sets[EL], extremality[FA], [DAV] or continuous selection Michael[M1] and the second type involved with a multi- purpose system of axioms. The theory of convex invariants has grown out of the
classical results of Helly, Radon and Caratheodory in Euclidean spaces. Levi gave the first general definition of the invariants Helly number and Radon number. The notation of a convex structure was introduced by Jamison[JA4] and that of generating degree was introduced by Van de Vel[VAD8]. We also prove that for a non-coarse convex structure, rank is less than or equal to the generating degree, and also generalize Tverberg’s theorem using infinite partition numbers. Compare the transfinite topological and transfinite convex dimensions
Sajeev, S Nair; Dr.Krishnamoorthy,A(Cochin University of Science and Technology, September 2, 2011)
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Abstract:
In this thesis we have developed a few inventory models in which items are served to the customers after a processing time. This leads to a queue of demand even when items are available. In chapter two we have discussed a problem involving search of orbital customers for providing inventory. Retrial of orbital customers was also considered in that chapter; in chapter 5 also we discussed retrial inventory model which is sans orbital search of customers. In the remaining chapters (3, 4 and 6) we did not consider retrial of customers, rather we assumed the waiting room capacity of the system to be arbitrarily large. Though the models in chapters 3 and 4 differ only in that in the former we consider positive lead time for replenishment of inventory and in the latter the same is assumed to be negligible, we arrived at sharper results in chapter 4. In chapter 6 we considered a production inventory model with production time distribution for a single item and that of service time of a customer following
distinct Erlang distributions. We also introduced protection of production and service stages and investigated the optimal values of the number of stages to be protected.
Description:
Department of Mathematics,
Cochin University of Science And Technology.
Remadevi,S; Narayanan Namboodiri,M N(Department of Mathematics,Faculty of Science, 2003)
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Abstract:
This study is to look the effect of change in the ordering of the Fourier system on Szegö’s classical observations of asymptotic distribution of eigenvalues of finite Toeplitz forms.This is done by checking proofs and Szegö’s properties in the new set up.The Fourier system is unconditional [19], any arbitrary ordering of the Fourier system forms a basis for the Hilbert space L2 [-Π, Π].Here study about the classical Szegö’s theorem.Szegö’s type theorem for operators in L2(R+) and check its validity for certain multiplication operators.Since the trigonometric basis is not available in L2(R+) or in L2(R) .This study discussed about the classes of orderings of Haar System in L2 (R+) and in L2(R) in which Szegö’s Type TheoreT Am is valid for certain multiplication operators.It is divided into two sections. In the first section there is an ordering to Haar system in L2(R+) and prove that with respect to this ordering, Szegö’s Type theorem holds for general class of multiplication operators Tƒ with multiplier ƒ ε L2(R+), subject to some conditions on ƒ.Finally in second section more general classes of ordering of Haar system in L2(R+) and in L2(R) are identified in such a way that for certain classes of multiplication operators the asymptotic distribution of eigenvalues exists.
Veena Gopalan, E; Dr.Anantharaman, M R(Cochin University of Science & Technology, June , 2009)
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Abstract:
This thesis lays importance in the preparation and characterization of a
few selected representatives of the ferrite family in the nanoregime. The candidates being manganese zinc ferrite and cobalt ferrite prepared by coprecipitation
and sol-gel combustion techniques respectively. The thesis not only
stresses importance on the preparation techniques and optimization of the reaction
conditions, but emphasizes in investigating the various properties namely
structural, magnetic and electrical. Passivated nickel nanocomposites are
synthesized using polystyrene beads and adopting a novel route of ion exchange
reduction. The structural and magnetic properties of these magnetic
nanocomposites are correlated. The magnetocaloric effect (MCE) exhibited by
these materials are also investigated with a view to finding out the potential of
these materials as magnetic refrigerants. Calculations using numerical methods
are employed to evaluate the entropy change on selected samples.
Description:
Department of Physics,
Cochin University of Science & Technology
Hysen, Thomas; Anantharaman, M R(Cochin University of Science and Technology, June , 2013)
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Abstract:
The development of new materials has been the hall mark of human civilization. The quest for making new devices and new materials has prompted humanity to pursue new methods and techniques that eventually has given birth to modern science and technology. With the advent of nanoscience and nanotechnology, scientists are trying hard to tailor materials by varying their size and shape rather than playing with the composition of the material. This, along with the discovery of new and sophisticated imaging tools, has led to the discovery of several new classes of materials like (3D) Graphite, (2D) graphene, (1D) carbon nanotubes, (0D) fullerenes etc. Magnetic materials are in the forefront of applications and have beencontributing their share to remove obsolescence and bring in new devices based on magnetism and magnetic materials. They find applications in various devices such as electromagnets, read heads, sensors, antennas, lubricants etc. Ferromagnetic as well as ferrimagnetic materials have been in use in the form of various devices. Among the ferromagnetic materials iron, cobalt and nickel occupy an important position while various ferrites finds applications in devices ranging from magnetic cores to sensors.
Description:
Department of Physics, Cochin University of Science and Technology
Abdul Sathar,E I; Muraleedharan Nair,K R(Department of Statistics, Faculty of Science, 2002)
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Abstract:
The present study focuses attention on defining certain measures of income inequality for the truncated distributions and characterization of probability distributions using the functional form of these measures, extension of some measures of inequality and stability to higher dimensions, characterization of bivariate models using the above concepts and estimation of some measures of inequality using the Bayesian techniques. The thesis defines certain measures of income inequality for the truncated distributions and studies the effect of truncation upon these measures. An important measure used in Reliability theory, to measure the stability of the component is the residual entropy function. This concept can advantageously used as a measure of inequality of truncated distributions. The geometric mean comes up as handy tool in the measurement of income inequality. The geometric vitality function being the geometric mean of the truncated random variable can be advantageously utilized to measure inequality of the truncated distributions. The study includes problem of estimation of the Lorenz curve, Gini-index and variance of logarithms for the Pareto distribution using Bayesian techniques.
Rahana, Yoosuf; Dr.Jayaraj, M K(Cochin University of Science & Technology, October , 2007)
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Abstract:
Two stage processes consisting of precursor preparation by thermal
evaporation followed by chalcogenisation in the required atmosphere is
found to be a feasible technique for the PV materials such as n-Beta In2S3,
p-CulnSe2, p-CulnS2 and p-CuIn(Sel_xSx)2. The growth parameters such as
chalcogenisation temperature and duration of chalcogenisation etc have been
optimised in the present study.Single phase Beta-In2S3 thin films can be obtained by sulfurising the indium
films above 300°C for 45 minutes. Low sulfurisation temperatures required
prolonged annealing after the sulfurisation to obtain single phase Beta-1n2S3,
which resulted in high material loss. The maximum band gap of 2.58 eV was
obtained for the nearly stoichiometric Beta-In2S3 film which was sulfurised at
350°C. This wider band gap, n type Beta-In2S3 can be used as an alternative to
toxic CdS as window layer in photovoltaics .The systematic study on the structural optical and electrical properties of
CuInSe2 films by varying the process parameters such as the duration of
selenization and the selenization temperature led to the conclusion that for
the growth of single-phase CuInSe2, the optimum selenization temperature is
350°C and duration is 3 hours. The presence of some binary phases in films
for shorter selenization period and lower selenization temperature may be
due to the incomplete reaction and indium loss. Optical band gap energy of
1.05 eV obtained for the films under the optimum condition.In order to obtain a closer match to the solar spectrum it is desirable to
increase the band gap of the CulnSe2 by a few meV . Further research
works were carried out to produce graded band gap CuIn(Se,S)2 absorber
films by incorporation of sulfur into CuInSe2. It was observed that when the
CulnSe2 prepared by two stage process were post annealed in sulfur atmosphere, the sulfur may be occupying the interstitial positions or forming
a CuInS2 phase along with CuInSe2 phase. The sulfur treatment during the
selenization process OfCu11 ln9 precursors resulted in Culn (Se,S)2 thin films.
A band gap of 1.38 eV was obtained for the CuIn(Se,S)2.The optimised thin films n-beta 1n2S3, p-CulnSe2 and p-Culn(Sel-xSx)2 can be
used for fabrication of polycrystalline solar cells.
Description:
Department of Physics,
Cochin University of Science and Technology
Ajitha, S; Dr.Sugunan, S(Cochin University of Science and Technology, September , 2008)
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Abstract:
Mesoporous materials are of great interest to the materials community because of their potential applications for catalysis,separation of large molecules,medical implants,semiconductors,magnetoelectric devices.The thesis entitled 'Ordered Mesoporous Silica as supports for immobilization of Biocatalyst' presents how the pore size can be tuned without the loss in ordered structure for the entrapment of an industially important biocatalyst-amylase.Immobilization of enzymes on ordered mesoporous material has triggered new ooportunities for stabilizing enzymes with improved intrinsic and operational stabilities.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Kannan, V; Dr. Sreekumar, K(Cochin University of Science & Technology, August , 2011)
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Abstract:
Catalysis is a technologically important field which determines the quality of life in future. Catalyst research in pharmaceutical industry,fine chemical synthesis and emission control demands supported catalysts in bulk quantities.In the present work it was observed that clay supported catalysts mentioned in various chapters could also be used for the synthesis of similar molecules. The K10Ti catalyst can be used for the synthesis similar substituted imidazole derivatives under solvent free conditions and synthetically important Mannich bases of substrates containing various substitutes.Al-pillared saponite can be used for acetalation of other polyhydroxy compounds like glycerol,mannitol etc.Cu-Pd KSF catalyst has found application in C-C bond forming reactions which can be applied to other reactions and similar methods can be adopted for the synthesis of other catalyst by changing the transition metals. Montmorillonite K10 catalysed synthesis of triarylpyridines can be extended to the synthesis tetrasubstuted pyroles.K10Ti can also be utilized for the synthesis of similar heterocycles.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology