Hareeshkumar, P V; Dr.Basil, Mathew(Cochin University of Science And Technology, January , 1992)
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Abstract:
The Arabian Sea is an area of complex air-sea interaction
processes with seasonal reversing monsoons. The associated
thermohaline variability in the upper layers appears to
control the large scale monsoon flow which is not yet
completely understood.
The variability in the thermohaline fields is known to
occur in temporal domain ranging from intra-diurnal to
inter-annual time scales and on spatial domains of few tens of
kilometers to few thousands of kilometers. In the Arabian Sea
though the surface temperature was routinely measured by both
conventional measurements and satellites, the corresponding
information on the subsurface thermohaline field is very
sparse due to the lack cw adequate measurements. In such
cases the numerical models offer promise in providing
information on the subsurface features given an initial
thermohaline field and surface heat flux boundary conditions.
This thesis is an outcome of investigations carried out
on the various aspects of the thermohaline variability on
different time scales. In addition to the description of the
mean annual cycle. the one dimensional numerical models of
Miller (1976) and Price et a1 (1986) are utilised to simulate
the observed mixed layer characteristics at selected locations
in the Arabian Sea on time scales ranging from intra-diurnal
to synoptic scales under variable atmospheric forcing.
Anju, K. Augustine; Dr.Kailasnath, M; Prof. V P N Nampoori(Cochin University of Science and Technology, June 23, 2015)
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Abstract:
In general, linear- optic, thermo- optic and nonlinear- optical studies
on CdSe QDs based nano
uids and their special applications in solar
cells and random lasers have been studied in this thesis. Photo acous-
tic and thermal lens studies are the two characterization methods used
for thermo- optic studies whereas Z- scan method is used for nonlinear-
optical charecterization. In all these cases we have selected CdSe QDs
based nano
uid as potential photonic material and studied the e ect of
metal NPs on its properties.
Linear optical studies on these materials have been done using vari-
ous characterization methods and photo induced studies is one of them.
Thermal lens studies on these materials give information about heat
transport properties of these materials and their suitability for applica-
tions such as coolant and insulators. Photo acoustic studies shows the
e ect of light on the absorption energy levels of the materials. We have
also observed that these materials can be used as optical limiters in the
eld of nonlinear optics. Special applications of these materials have
been studied in the eld of solar cell such as QDSSCs, where CdSe QDs
act as the sensitizing materials for light harvesting. Random lasers have
many applications in the eld of laser technology, in which CdSe QDs
act as scattering media for the gain.
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
Shivaprasad,Amaravayal; Dr.Revichandran,C(Cochin University Of Science And Technology, May , 2013)
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Abstract:
Hydrodynamic characteristics of an estuary resulting from
interaction of tide and river runoff are important since problems
regarding flood, salinity intrusion, water quality, ecosystem and sedimentation are ubiquitous. The present study focuses on such
hydrodynamic aspects in the Cochin estuary.
Most of the estuaries that come under the influence of Indian
Summer Monsoon and for which the salinity is never in a steady
state at any time of the year are generally shallow and convergent,
i.e. the width decreases rapidly from mouth to head. In contrast,
Cochin estuary is wider towards the upstream and has no typical
river mouth, where the rivers are joining the estuary along the length
of its channel .Adding to the complexity it has dual inlets and the
tidal range is 1 m which is lower than other Indian estuaries along
west coast. These typical physical features lead to its unique
hydrodynamic characteristics. Therefore the thesis objectives are: I)
to study the influence of river runoff on tidal propagation using
observations and a numerical model ii) to study stratification and
property distributions in Cochin estuary iii) to understand salinity
distributions and flushing characteristics iv) to understand the
influence of saltwater barrage on tides and salinity v) To evaluate
several classification schemes for the estuary
Description:
National Institute of Oceanography, Regional centre, Cochin- 18
Suresh, V N; Dr.Wilson, P R(Cochin University of Science And Technology, June , 2000)
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Abstract:
Poor project planning, implementation and control and the subsequent cost and time overruns are ubiquitous features that have been posing serious concern at all levels - state, national and international. It results in wastage of the nation's scarce resources and retards the socio-economic progress. Although several studies peripheral on project overruns have been made at the national level, no serious attempt has been made at the state level to identify the magnitude of overruns, their causes and impacts on industrial projects. The present study "Time and Cost Overruns of Industrial Projects in Kerala" is an earnest attempt to probe in depth the time and cost overruns and their impact on industrial projects. The study places emphasise on the identification of the real reasons behind the cost and time overruns. It also covers the present project management practices of industrial projects in Kerala.
Description:
School of management studies, Cochin University of Science And Technology
Subin, Joseph P; 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
Sethulakshmi, N; Dr. Anantharaman, M. R.(Cochin University of Science and Technology, September , 2014)
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Abstract:
The present thesis work focuses on hole doped lanthanum manganites and their thin film forms. Hole doped lanthanum manganites with higher substitutions of sodium are seldom reported in literature. Such high sodium substituted lanthanum manganites are synthesized and a detailed investigation on their structural and magnetic properties is carried out. Magnetic nature of these materials near room
temperature is investigated explicitly. Magneto caloric application potential of these materials are also investigated. After a thorough investigation of the bulk samples, thin films of the bulk counterparts are also investigated. A magnetoelectric composite with ferroelectric and ferromagnetic components is developed using pulsed laser deposition and the variation in the magnetic and electric properties are investigated. It is established that such a composite could be realized as a potential field effect device. The central theme of this thesis is also on manganites and is with the twin objectives of a material study leading to the demonstration of a device. This is taken up for investigation. Sincere efforts are made to synthesize phase pure compounds. Their structural evaluation, compositional verification and evaluation of ferroelectric and ferromagnetic properties are also taken up. Thus the focus of this investigation is related to the investigation of a magnetoelectric and magnetocaloric application potentials of doped lanthanum manganites with sodium substitution. Bulk samples of sodium substituted lanthanum manganites. Bulk samples of sodium substituted lanthanum manganites with Na substitution ranging from 50 percent to 90 percent were synthesized using a modified citrate gel method and were found to be orthorhombic in structure belonging to a pbnm spacegroup. The variation in lattice parameters and unit cell volume with sodium concentration were also dealt with. Magnetic measurements revealed that magnetization decreased with increase in sodium concentrations.
Prabhudeva,K N; Dr.Ravindranatha Menon,N(Cochin University of Science and Technology, August , 1987)
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Abstract:
In this thesis certain important aspects of heavy metal toxicity have been worked out. Recent studies have clearly shown that when experimental media contained more than one heavy metals, such metals could conspicuously influence the toxic reaction of the animals both in terms of quantity and nature. The experimental results available on individual metal toxicity show that, in majority of such results, unrealistically high concentrations of dissolved metals are involved. A remarkable number of factors have been shown to influence metal toxicity such as various environmental factors particularly temperature and salinity, the condition of the organism and the ability of some of the marine organisms to adapt to metallic contamination. Further, some of the more sensitive functions like embryonic and larval development, growth and fecundity, oxygen utilization and the function of various enzymes are found to be demonstrably sensitive in the presence of heavy metals. However, some of the above functions could be compensated for by adaptive process. If it is assumed that the presence of a single metal in higher concentrations could affect the life function of marine animals, more than one metal in the experimental media should manifest such effects in a greater scale. Commonly known as synergism or more than additivity, majority of heavy metals bring about synergistic reaction .The work presented in this thesis comprises lethal and sublethal toxicities of different salt forms of copper and silver on the brown mussel Perna indica. during the present investigation sublethal concentrations of copper and silver in their dent effects on survival, oxygen consumption, filtration, accumulation and depuration on Perna indica. The results are presented under different sections to make the presentation meaningful .
Description:
Division of Marine
Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology
Asha, M R; Dr.Kuttyamma, V J(Cochin University of Science and Technology, 2001)
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Abstract:
Asha M. R
This thesis Entitled Toxicological effects of copper and mercury on the fish macerones gulio
(hamiloton – buchanan).Chapter 1. In this chapter, a broad outline of heavy metal uptake, requirement of a suitable bio — monitoring organism, criteria for a standard test fish, and suitability of Macrones
gulig for the toxicological study are given. Chapter 2. This chapter deals with the lethal toxicity bioassays to find the 96 hr LC 50 of copper and mercury for the fish Macrones gglig. The experimental results indicated that of the two metals tested, copper was more toxic than mercury.Chapter 3. The effect of copper and mercury on the haemoglobin, haematocrit, erythrocyte count, MCV, MCH and MCHC was studied.Chapter 4. The glycogen and protein contents of liver and muscle after exposure to copper and mercury were studied. There was a significant decrease of glycogen in the liver and muscle of metal treated fishes.Chapter 5. The histopathological changes of the tissues like liver, kidney and gill after exposure to copper and mercury were studied.
Description:
School of
Marine Sciences, Department of Marinebiology, Microbiology and Biochemistry, Cochin University of Science and Technology