Jasmine, Mathew; Dr. Ebenezer, D D(Defence Research and Development Organisation, September , 2011)
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Abstract:
New mathematical methods to analytically investigate linear acoustic radiation
and scattering from cylindrical bodies and transducer arrays are presented. Three
problems of interest involving cylinders in an infinite fluid are studied. In all the three
problems, the Helmholtz equation is used to model propagation through the fluid and the
beam patterns of arrays of transducers are studied.
In the first problem, a method is presented to determine the omni-directional and
directional far-field pressures radiated by a cylindrical transducer array in an infinite
rigid cylindrical baffle. The solution to the Helmholtz equation and the displacement
continuity condition at the interface between the array and the surrounding water are
used to determine the pressure. The displacement of the surface of each transducer is in
the direction of the normal to the array and is assumed to be uniform. Expressions are
derived for the pressure radiated by a sector of the array vibrating in-phase, the entire
array vibrating in-phase, and a sector of the array phase-shaded to simulate radiation
from a rectangular piston. It is shown that the uniform displacement required for
generating a source level of 220 dB ref. μPa @ 1m that is omni directional in the
azimuthal plane is in the order of 1 micron for typical arrays. Numerical results are
presented to show that there is only a small difference between the on-axis pressures
radiated by phased cylindrical arrays and planar arrays. The problem is of interest
because cylindrical arrays of projectors are often used to search for underwater objects.
In the second problem, the errors, when using data-independent, classical, energy
and split beam correlation methods, in finding the direction of arrival (DOA) of a plane
acoustic wave, caused by the presence of a solid circular elastic cylindrical stiffener near
a linear array of hydrophones, are investigated. Scattering from the effectively infinite
cylinder is modeled using the exact axisymmetric equations of motion and the total
pressures at the hydrophone locations are computed. The effect of the radius of the
cylinder, a, the distance between the cylinder and the array, b, the number of
hydrophones in the array, 2H, and the angle of incidence of the wave, α, on the error in
finding the DOA are illustrated using numerical results. For an array that is about 30
times the wavelength and for small angles of incidence (α<10), the error in finding the
DOA using the energy method is less than that using the split beam correlation method
with beam steered to α; and in some cases, the error increases when b increases; and the errors in finding the DOA using the energy method and the split beam correlation
method with beam steered to α vary approximately as a7 / 4 . The problem is of interest
because elastic stiffeners – in nearly acoustically transparent sonar domes that are used to
protect arrays of transducers – scatter waves that are incident on it and cause an error in
the estimated direction of arrival of the wave.
In the third problem, a high-frequency ray-acoustics method is presented and
used to determine the interior pressure field when a plane wave is normally incident on a
fluid cylinder embedded in another infinite fluid. The pressure field is determined by
using geometrical and physical acoustics. The interior pressure is expressed as the sum
of the pressures due to all rays that pass through a point. Numerical results are presented
for ka = 20 to 100 where k is the acoustic wavenumber of the exterior fluid and a is the
radius of the cylinder. The results are in good agreement with those obtained using field
theory. The directional responses, to the plane wave, of sectors of a circular array of
uniformly distributed hydrophones in the embedded cylinder are then computed. The
sectors are used to simulate linear arrays with uniformly distributed normals by using
delays. The directional responses are compared with the output from an array in an
infinite homogenous fluid. These outputs are of interest as they are used to determine the
direction of arrival of the plane wave. Numerical results are presented for a circular array
with 32 hydrophones and 12 hydrophones in each sector. The problem is of interest
because arrays of hydrophones are housed inside sonar domes and acoustic plane waves
from distant sources are scattered by the dome filled with fresh water and cause
deterioration in the performance of the array.
Finla, Chathu; Dr. Paulose, C S(Cochin University of Science and Technology, February , 2007)
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Abstract:
In the present work, the role of oxygen, epinephrine and glucose
supplementation in regulating neurotransmitter contents, adrenergic and glutamate
receptor binding parameters in the cerebral cortex of experimental groups of neonatal
rats were investigated. The study of neurotransmitters and their receptors in the
cerebral cortex and the EEG pattern in the brain regions of neonatal rats were taken as
index for brain damage due to hypoxia, oxygen and epinephrine. Real-Time PCR work was done to confirm the binding parameters. Second messenger, cyclic
Adenosine Monophosphate (cAMP) was assayed to find the functional correlation of
the receptors. Behavioural studies were carried out to confirm the biochemical and
molecular studies. The efficient and timely supplementation of glucose plays a crucial
role in correcting the molecular changes due to hypoxia, oxygen and epinephrine. The
addictive neuronal damage effect due to oxygen and epinephrine treatment is another
important observation. The corrective measures from the molecular study brought to
practice will lead to maintain healthy intellectual capacity during the later
developmental stages, which has immense clinical significance in neonatal care.
Description:
Department of Biotechnology, Cochin
University of Science and Technology
Ani Das, V; Paulose, C S(Department of Biotechnology, Faculty of Science, August , 2000)
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Abstract:
In the present study, the changes in the brain EPI (Epinephrine), adrenergic receptors and the receptor gene expression were investigated during pancreatic regeneration and insulin secretion. The changes in the pancreatic islet EPI and adrenergic receptors were also studied in the pancreatectomised rats. The regulatory function of EPI in association with Epidermal growth factor (EGF) and glucose were investigated in rat islet cultures. In vitro studies were carried out using antagonists for adrenergic receptor subtypes to see their involvement in the islet DNA synthesis. The mechanism by which the peripheral EPI regulate insulin secretion was also investigated by studying the nuclear binding proteins in the pancreatic islets during pancreatic regeneration and diabetes. The study reveals that EPI can regulate the pancreatic islet cell proliferation by controlling the insulin synthesis and secretion. The brain adrenergic receptor gene expression and functional correlation regulate the pancreatic adrenergic receptors. The functional balance of α and β-adrenergic receptors controls the insulin secretion and pancreatic β-cell proliferation, which will have immense clinical significance in the treatment of Diabetes mellitus.
The present study was undertaken to elucidate the nutritional and pathological changes associated with aflatoxin B1 toxicity in Penaeus monodon and to determine the efficacy of vitamins E and K, and Amrita Bindu, herbal mixture in ameliorating the toxicity of AFB1.
The main objectives the study is to document the pathological and immunological changes in P.monodon fed with AFB1 incorporated diets and to delineate the histological and ultrastructural changes and determine the presence of AFB1 residue in the shrimp body, to evaluate the growth performance of feed efficiency in P. monodon post larvae fed AFB1 added diets, to assess the interactive effect of heavy metals like copper and cadmium at sub-lethal levels in P. monodon postlarve fed AFB1 added diets, to decipher the ameliorative action of Vitamins E & K and a spicy herbal mixture, Amrita Bindu on AFB1 in P.monodon sub-adults. The study has revealed that Aflatoxin B1 significantly affects protein, lipid and carbohydrate metabolism in the shrimp penaeus monodon. The remarkable effect was observed in the immune system, as AFB1 has elevatod the immune response during initial days of exposure and prolonged exposure to the toxin leads to weakening of the animal’s immunity. Aflatoxin B1 level above 50 ppb severely affected the growth and feed utilization which in turn reflects the damage caused to the hepatopancreas as evident from the histological and ultrastructural observations.
Manjusha, K; Dr. Saramma, A V(Cochin University of Science and Technology, July , 2011)
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Abstract:
The thesis presents a detailed account of the alkaline protease produced by Vibrio sp.(V26) a mangrove isolate,and the application of this enzyme in different fields.The protease producer strain was identified on the basis of biochemical characteristice,putative virulence traits and 16S rRNA gene sequencing.The purification and characterization of the protease has been carried out. Along with this, an attempt has been made to identifiy the protease gene. The physical parameters as well as the media components influencing protease production were optimized using Response Surfce Methodology(RSM).The scale up of the application of the protease from Vibrio sp.(V26) in the dissociation of cells in animal cell culture,in the recovery of silver from used X-ray films as well as an ingredient in commercial detergents were investigated.
Description:
Dept.of Marine Biology,Microbiology and Biochemistry,Cochin University of Science and Technology
Sreeja,Chellappan; Chandrasekaran,M(Cochin University of Science and Technology, October , 2005)
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Abstract:
The thesis entitled “Alkaline Protease Production by Marine Fungus Engyodontium BTMFS 10”.Proteases are the single class of enzymes, which occupy a pivotal position with respect to their application in both physiological and commercial filed. Protease in the industrial market is expected to increase further in the coming year. The current trend is to use microbial enzymes since they provide a greater diversity of catalytic activities and can be produced more economically. Main objective of theses studies are the optimization of various physicochemical factors in the solid state fermentation for the production of alkaline protease enzyme, characterization of the enzyme, evaluation of the enzyme for various industrial application. The result obtained the during the course of theses study indicate the scope for the utilization of this study Marine Fungus E. Album for extra cellular protease production employing solid state fermentation
Surekha Mariam, Varghese; Dr. Poulose Jacob, K(Cochin University of Science & Technology, March , 2008)
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Abstract:
Modern computer systems are plagued with stability and security
problems: applications lose data, web servers are hacked, and systems crash under
heavy load. Many of these problems or anomalies arise from rare program
behavior caused by attacks or errors. A substantial percentage of the web-based
attacks are due to buffer overflows. Many methods have been devised to detect
and prevent anomalous situations that arise from buffer overflows. The current
state-of-art of anomaly detection systems is relatively primitive and mainly
depend on static code checking to take care of buffer overflow attacks. For
protection, Stack Guards and I-leap Guards are also used in wide varieties.This dissertation proposes an anomaly detection system, based on
frequencies of system calls in the system call trace. System call traces represented
as frequency sequences are profiled using sequence sets. A sequence set is
identified by the starting sequence and frequencies of specific system calls. The
deviations of the current input sequence from the corresponding normal profile in
the frequency pattern of system calls is computed and expressed as an anomaly
score. A simple Bayesian model is used for an accurate detection.Experimental results are reported which show that frequency of system
calls represented using sequence sets, captures the normal behavior of programs
under normal conditions of usage. This captured behavior allows the system to detect anomalies with a low rate of false positives. Data are presented which show
that Bayesian Network on frequency variations responds effectively to induced
buffer overflows. It can also help administrators to detect deviations in program
flow introduced due to errors.
Description:
Department of Computer
Science, Cochin University of Science and Technology.
Saji, K J; Dr.Jayaraj, M K(Cochin University of Science & Technology, October , 2008)
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Abstract:
This work
mainly concentrate to understand the optical and electrical properties of
amorphous zinc tin oxide and amorphous zinc indium tin oxide thin films
for TFT applications. Amorphous materials are promising in achieving
better device performance on temperature sensitive substrates compared
to polycrystalline materials. Most of these amorphous oxides are multicomponent
and as such there exists the need for an optimized chemical
composition. For this we have to make individual targets with required
chemical composition to use it in conventional thin film deposition techniques
like PLD and sputtering. Instead, if we use separate targets for
each of the cationic element and if separately control the power during the
simultaneous sputtering process, then we can change the chemical composition
by simply adjusting the sputtering power. This is what is done in co-sputtering technique. Eventhough there had some reports about thin
film deposition using this technique, there was no reports about the use
of this technique in TFT fabrication until very recent time. Hence in this
work, co-sputtering has performed as a major technique for thin film deposition
and TFT fabrication. PLD were also performed as it is a relatively
new technique and allows the use high oxygen pressure during deposition.
This helps to control the carrier density in the channel and also favours the
smooth film surface. Both these properties are crucial in TFT.Zinc tin oxide material is interesting in the sense that it does not contain
costly indium. Eventhough some works were already reported in ZTO based
TFTs, there was no systematic study about ZTO thin film's various optoelectronic
properties from a TFT manufacturing perspective. Attempts
have made to analyse the ZTO films prepared by PLD and co-sputtering.
As more type of cations present in the film, chances are high to form an
amorphous phase. Zinc indium tin oxide is studied as a multicomponent
oxide material suitable for TFT fabrication.
Description:
Department of Physics,
Cochin University of Science and Technology
Bindu, K; Vijayakumar, K P(Cochin University of Science & Technology, May , 2002)
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Abstract:
In the present work, we describe our efforts to develop device quality
CuInSe2, films through low cost, simple and eco-friendly hybrid techniques. The
most important point to be highlighted here is that the method fully avoids the use
of poisonous gases such as H2Se/Se vapour. Instead, selenisation is achieved
through solid state reaction between amorphous selenium and polycrystalline
metal layers resulting in both binary and ternary selenides. Thin films of
amorphous selenium (a-Se) used for this is deposited using Chemical Bath
Deposition (CBD). CulnSe2 films are prepared through the selenisation process.
Another PV material, indium selenide (In2Se3) thin films are also prepared using
this process.
Description:
Department of Physics, Cochin University of
Science and Technology