Santhosh, B; Dr.Nandakumar, C G(Cochin University of Science & Technology, December , 2010)
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Abstract:
Three dimensional (3D) composites are strong contenders for the structural applications in situations like aerospace,aircraft and automotive industries where multidirectional thermal and mechanical stresses exist. The presence of reinforcement along the thickness direction in 3D composites,increases the through the thickness stiffness and strength properties.The 3D preforms can be manufactured with numerous complex architecture variations to meet the needs of specific applications.For hot structure applications Carbon-Carbon(C-C) composites are generally used,whose property variation with respect to temperature is essential for carrying out the design of hot structures.The thermomechanical behavior of 3D composites is not fully understood and reported.The methodology to find the thermomechanical properties using analytical modelling of 3D woven,3D 4-axes braided and 3D 5-axes braided composites from Representative Unit Cells(RUC's) based on constitutive equations for 3D composites has been dealt in the present study.High Temperature Unidirectional (UD) Carbon-Carbon material properties have been evaluated using analytical methods,viz.,Composite cylinder assemblage Model and Method of Cells based on experiments carried out on Carbon-Carbon fabric composite for a temparature range of 300 degreeK to 2800degreeK.These properties have been used for evaluating the 3D composite properties.From among the existing methods of solution sequences for 3D composites,"3D composite Strength Model" has been identified as the most suitable method.For thegeneration of material properies of RUC's od 3D composites,software has been developed using MATLAB.Correlaton of the analytically determined properties with test results available in literature has been established.Parametric studies on the variation of all the thermomechanical constants for different 3D performs of Carbon-Carbon material have been studied and selection criteria have been formulated for their applications for the hot structures.Procedure for the structural design of hot structures made of 3D Carbon-Carbon composites has been established through the numerical investigations on a Nosecap.Nonlinear transient thermal and nonlinear transient thermo-structural analysis on the Nosecap have been carried out using finite element software NASTRAN.Failure indices have been established for the identified performs,identification of suitable 3D composite based on parametric studies on strength properties and recommendation of this material for Nosecap of RLV based on structural performance have been carried out in this Study.Based on the 3D failure theory the best perform for the Nosecap has been identified as 4-axis 15degree braided composite.
Description:
Dept.of Ship Technology,Cochin University of Science and Technology
Subin P, Joseph; Dr.Jathavedan, M(Cochin University of Science and Technology, January , 2006)
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Abstract:
In this thesis we are studying possible invariants in hydrodynamics and hydromagnetics.
The concept of flux preservation and line preservation of vector fields, especially
vorticity vector fields, have been studied from the very beginning of the study of fluid
mechanics by Helmholtz and others. In ideal magnetohydrodynamic flows the magnetic
fields satisfy the same conservation laws as that of vorticity field in ideal hydrodynamic
flows. Apart from these there are many other fields also in ideal hydrodynamic and magnetohydrodynamic flows which preserves flux across a surface or whose vector lines
are preserved.
A general study using this analogy had not been made for a long time. Moreover
there are other physical quantities which are also invariant under the flow, such as
Ertel invariant. Using the calculus of differential forms Tur and Yanovsky classified
the possible invariants in hydrodynamics. This mathematical abstraction of physical
quantities to topological objects is needed for an elegant and complete analysis of
invariants.Many authors used a four dimensional space-time manifold for analysing fluid flows.
We have also used such a space-time manifold in obtaining invariants in the usual three
dimensional flows.In chapter one we have discussed the invariants related to vorticity field using
vorticity field two form w2 in E4. Corresponding to the invariance of four form w2 ^ w2
we have got the invariance of the quantity E. w. We have shown that in an isentropic
flow this quantity is an invariant over an arbitrary volume.In chapter three we have extended this method to any divergence-free frozen-in
field. In a four dimensional space-time manifold we have defined a closed differential
two form and its potential one from corresponding to such a frozen-in field. Using this
potential one form w1
, it is possible to define the forms dw1 , w1 ^ dw1 and dw1 ^ dw1
.
Corresponding to the invariance of the four form we have got an additional invariant
in the usual hydrodynamic flows, which can not be obtained by considering three
dimensional space.In chapter four we have classified the possible integral invariants associated with
the physical quantities which can be expressed using one form or two form in a three
dimensional flow. After deriving some general results which hold for an arbitrary dimensional
manifold we have illustrated them in the context of flows in three dimensional
Euclidean space JR3. If the Lie derivative of a differential p-form w is not vanishing,then the surface integral of w over all p-surfaces need not be constant of flow. Even
then there exist some special p-surfaces over which the integral is a constant of motion,
if the Lie derivative of w satisfies certain conditions. Such surfaces can be utilised
for investigating the qualitative properties of a flow in the absence of invariance over
all p-surfaces. We have also discussed the conditions for line preservation and surface
preservation of vector fields. We see that the surface preservation need not imply the
line preservation. We have given some examples which illustrate the above results.
The study given in this thesis is a continuation of that started by Vedan et.el. As
mentioned earlier, they have used a four dimensional space-time manifold to obtain
invariants of flow from variational formulation and application of Noether's theorem.
This was from the point of view of hydrodynamic stability studies using Arnold's
method.
The use of a four dimensional manifold has great significance in the study of knots
and links. In the context of hydrodynamics, helicity is a measure of knottedness of
vortex lines. We are interested in the use of differential forms in E4 in the study of
vortex knots and links. The knowledge of surface invariants given in chapter 4 may
also be utilised for the analysis of vortex and magnetic reconnections.
Description:
Department of Mathematics,
Cochin University of Science and Technology
Rekha,A; Krishnamoorthy,A(Department of Mathematics, Faculty of Science, 2000)
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Abstract:
In this thesis T-policy is implemented to the inventory system with random lead time and also repair in the reliability of k-out-of-n system. Inventory system may be considered as the system of keeping records of the amounts of commodities in stock. Reliability is defined as the ability of an entity to perform a required function under given conditions for a given time interval. It is measured by the probability that an entity E can perform a required function under given conditions for the time interval. In this thesis considered k-out-of-n system with repair and two modes of service under T-policy. In this case first server is available always and second server is activated on elapse of T time units. The lead time is exponentially distributed with parameter and T is exponentially distributed with parameter from the epoch at which it was inactivated after completion of repair of all failed units in the previous cycle, or the moment n-k failed units accumulate. The repaired units are assumed to be as good as new. In this study , three different situations, ie; cold system, warm system and hot system. A k-out-of-n system is called cold, warm or hot according as the functional units do not fail, fail at a lower rate or fail at the same rate when system is shown as that when it is up.
Shali, N B; Dr.Sugunan, S(Cochin University of Science and Technology, April , 2006)
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Abstract:
Catalysis is a mature field with extensive practical applications in today's society.indeed,the catalysis of petroleum refining,fine chemical synthesis and emission control demands the production of catalysts in bulk quantities.Future improvement of these well established processes is likely to be incremental.On the other hand,the continuous demand for new products will require additional novel and innovative processes.The need for pollution abatement and prevention also imposes new demands on catalysis, and new processes are periodically advanced for the control of emission of gases as well as for remediation processes such as the cleaning of underground waters. The number of problems where catalysis can have a big impact is constantly growing.In general,science stimulated by the technology has enriched the field of catalysis in a way that has had broad and lasting value.The thesis"Transition metal and rare earth metal modified sol-gel titania: a versatile catalyst for organic transformations" accounts the preparation and characterization studies of both transition metals and rare earth metals modified sol-gel titania and its applications in industrially useful organic reactions.
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Department of Applied Chemistry,
Cochin University of Science and Technology
Manju, Sebastian; Dr.Mohammed Yusuff, K K(Cochin University of Science & Technology, July , 2010)
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Abstract:
Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.The convenient route of synthesis and thermal stability of Schiff base complexes have contributed significantly for their possible applications in catalysis,biology,medicine and photonics.Significant variations in cataltytic activity with structure and type are observed for these complexes.The thesis deals with synthsis and characterization of transition metal complexes of quinoxaline based Schiff base ligands and their catalytic activity study.The Schiff bases synthesized in the present study are quinoxaline-2-carboxalidine-2-amino-5-methylphenol,3-hydroxyquinoxaline-2-carboxalidine-2-amino-5-methylphenol,quinoxaline-2-aminothiophenol.They provide great structural diversity during complexation.To the best of our knowledge, the transition metal complexes of quinoxaline based Schiff bases are poorly utilised in academic and industrial research.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology
Sreesha, Sasi; Dr.Prathapachandra Kurup, M R(Cochin University of Science & Technology, October , 2008)
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Abstract:
Metallo-organic chemistry,incorporating the frontiers of both inorganic and organic chemical aspects,is a topic of utility concern.The first exploration of coordinated metal complexes dates back to the ninettenth century,during the days of Alfred Werner.Thereafter,inorganic chemistry witnessed a great outflow of coordination compounds,with unique structural characteristics and diverse applicatons.The diversity in structures exhibited by the coordination complexes of multidentate ligands have led to their usage as sensors,models for enzyme mimetic centers,medicines etc.The liganda chosen are of prime importance in determining the properties of coordination compounds.Schiff bases are compounds obtained by the condensation of an aidehyde or ketone with an amine.The chemical properties of Schiff bases and their complexes are widely explored in recent years owing to their pharmacological activity,their catalytic activities and so on.On the other hand pseudohalides like azide and thiocyanate are versatile candidates for the construction of dimeric or polymeric complexes having excellent properties and diverse applications.So a combination of the Schiff bases and the pseudohalogens for the synthesis of metal complexes can bring about interesting results.An attempt into this area is the besis of this Ph.D theis.
Description:
Department of Applied Chemistry,
Cochln University of Science and Technology
Suja, Krishnan; Dr. Prathapachandra Kurup, M R(Cochin University of Science and Technology, June , 2008)
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Abstract:
Coordination chemistry of pentadentate 2,6-diacetylpyridine
bis(thiosemicarbazone) Schiff base ligands has been intensively studied due to the versatility of the molecular chain in order to obtain very different
geometries as well as their broad therapeutic activity. Metal complexes of
thiosemicarbazone with aldehydes and ketones have been widely reported.
But there have been fewer reports on potential pentadentate
bis(thiosemicarbazones) formed from 2,6-diacetylpyridine. Keeping these in
view, we have synthesized four bis(thiosemicarbazone) systems with
2,6-diacetylpyridine. In the present work, the chelating behavior of
bis(thiosemicarbazones) are studied, with the aim of investigating the
influence of coordination exerts on their conformation and or configuration, in
connection with the nature of the metal and of the counter ion. The selection
of the 2,6-diacetylpyridine as the ketonic part was based on its capability to
form polynuclear complexes with different coordination number. The doubled
armed bis(thiosemicarbazones) can coordinate to a metal centre as dianionic
ligand by losing its amide protons or it can coordinate as monoanionic ligand
by losing its amide proton from one of the thiosemicarbazone moiety or it can
also be coordinate as neutral ligand. Hence it is interesting to explore the
coordinating capabilities of these ligands whether in neutral form or anionic
form and to study the structural variations occurring in the ligands during
complexation such as change in conformation.
Description:
Department of Applied Chemistry,
Cochin university of Science and Technology
Laly, K; Dr. Prathapachandra Kurup, M R(Cochin University of Science and Technology, July , 2011)
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Abstract:
In the present work,the chelating behaviour of thiosemicarbazones of a heterocyclic diketone, 2,6-diacetylpyridine is studied,with the aim of investigating the influence coordination exerts on their conformation and /or configuration, in connection with the nature of the metal and of the counter ion.The various possibilities like unsubstitution,ring incorporation at terminal nitrogen and condensation of one of the ketone group alone have been tried for ligand selection.Mainly first row transition metals like manganese,iron,nickel,copper,zinc and cadmium are studied.Metals like cobalt also were studied but could not result in fruitful isolation of the compound due to solubility problems.Different spectroscopic and characterization techniques have been utilized to reveal the nature of the metal and the ligands in coordinated metal complex.
Description:
Department of Applied Chemistry,Cochin University of Science and Technology
Philip,M P; George,K K(Department of Applied Economics, 2006)
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Abstract:
The study documents the long-term trends in financial intermediation by the principal player in Kerala’s credit system i.e., banking. The process of financial intermediation by the banking system, involving mobilization of deposits from savers and disbursal of credit to investors, is considered to be crucial in the process of economic development. The objective of the study is to explore the interrelationship between financial intermediation and economic growth in Kerala. In order to pursue this objective, the study examine, the trends in intermediation by the banking system in Kerala over a long period, the trend and pattern of bank deposits and credit in the State and Kerala’s economic growth, the trend in the growth and performance of financial intermediaries like the All India Financial Institutions, the links between banking and economic variables, and the difference in the growth trends of banking and economic variables between Kerala and India and the probable reasons for the difference
Mini, Kuriakose; Dr. Prathapachandra Kurup, M R(Cochin University of Science & Technology, December , 2006)
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Abstract:
The present work deals with the complexation of Schiff
bases of aroylhydrazides with various transition metal ions. The hydrazone
systems selected for study are capable of forming bridged polymeric structures
which is one of the fascinating subjects in the crystal engineering of coordination
polymers owing to their attractive new topologies and intriguing structural
features. Complexation with metal ions like copper, manganese, vanadium,
nickel, palladium, zinc and cadmium are tried. Various spectral techniques are
employed for characterization. The structures of some complexes have been well
established by single crystal X-ray diffraction studies.The work is presented in seven chapters and the last section deals with
summary and conclusion. The studies reveal that the aroylhydrazone systems vary
in their geometrical configuration depending on the substituents. The coordination
modes of the ligands also differ upon chelating with metal ions. One of the
hydrazone system selected for study proved that it could give rise to polymeric
metal complexes.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology