Mary, Alexander; Dr. Eby Thomas, Thachil(Cochin University of Science & Technology, April , 2008)
[+]
[-]
Abstract:
This research project explores the utilization of cardanol in various capacities for
rubber processing. Cardanol is a phenol with a long side chain in the meta position
of the benzene ring. It is obtained by the vacuum distillation of cashew Hut shell
liquid (CNSL) which is a cheap agro-byproduct. In this study, the plasticizer property
of cardanol was investigated in silica filled and HAF black filled NR, NBR, EPDM
and CR by comparing cure characteristics and mechanical properties of vulcanizates
containing conventional plasticizer with those containing cardanol as plasticizer. The
co-activator, antioxidant and accelerator properties were investigated in gum samples
of NR, NBR, EPDM and CR by comparing the properties of vulcanizates which
contain conventional co-activator, antioxidant and accelerator with those in which
each of them was replaced by cardanol. The general effectiveness of cardanol was
investigated by determination of cure time , measurement of physical and
mechanical properties, ageing studies, crosslink density, extractability, FTIR spectra,
TGA etc.The results show that cardanol can be a substitute for aromatic oil in both silica filled
and HAF black filled NR. Again, it can replace dioctyl phthalate in both silica filled
and HAF black filled NBR. Similarly, cardanol Can replace naphthenic oil in silica
filled as well as HAF black filled EPDM and CR. The cure characteristics and
mechanical properties are comparable in all the eight cases. The co-activator
property of cardanol is comparable to stearic acid in all the four rubbers. The cure
characteristics and mechanical properties in this case are also comparable. The
antioxidant ,property of cardanol is comparable to TQ in all the four rubbers. The
antioxidant property of cardanol is comparable to TQ in all the four case of NBR and
EPDM.The
accelerator property of cardarlol is comparable with CBS in the case of NBR and
EPDM. No accelerator property is observed in the case of NR. The accelerator
property of cardanol in CR is not negligible when compared with TMTD.
Description:
Department of Polymer Science and Rubber Technology,
Cochin University of Science and Technology
Anupam R, Chandran; Dr. Aanandan, C K(Cochin University of Science and Technology, June , 2007)
[+]
[-]
Abstract:
This thesis presents the Radar Cross Section measurements of different geometric structures such as flat plate,cylinder, corner reflector and circular cone loaded with fractal based metallo dielectric structures.Use of different fractal geometris,metallizations of different shapes as well as the frequency tanability is investigated for TE and TM polarization of the incident electromagnetic field.Application of fractal based metallo-dielectric structures results in RCS reduction over a wide range of frequency bands.RCS enhancement of dihedral corner is observed at certain acute and obtuse corner angles.The experimental results are validated using electromagnetic simulation softwares.
Description:
Department of Electronics,
Cochin University of Science and Technology
Baiju, K V; Dr. K G K Warrier(National Institute for Interdisciplinary Science and Technology,CSIR, November , 2007)
[+]
[-]
Abstract:
The present thesis develops from the point of view of titania sol-gel chemistry and an attempt is made to address the modification of the process for better photoactive titania
by selective doping and also demonstration of utilization of the process for the
preparation of supported membranes and self cleaning films.A general introduction to nanomaterials, nanocrystalline titania and sol-gel
chemistry are presented in the first chapter. A brief and updated literature review on
sol-gel titania, with special emphasis on catalytic and photocatalytic properties and
anatase to rutile transformation are covered. Based on critical assessment of the reported
information the present research problem has been defined.The second chapter describes a new aqueous sol-gel method for the preparation
of nanocrystalline titania using titanyl sulphate as precursor. This approach is novel
since no earlier work has been reported in the same lines proposed here. The sol-gel
process has been followed at each step using particle size, zeta potential measurements
on the sol and thermal analysis of the resultant gel. The prepared powders were then
characterized using X-ray diffraction, FTIR, BET surface area analysis and transmission
electron microscopy.The third chapter presents a detailed discussion on the physico-chemical
characterization of the aqueous sol-gel derived doped titania. The effect of dopants such
as tantalum, gadolinium and ytterbium on the anatase to rutile phase transformation,
surface area as well as their influence on photoactivity is also included.
The fourth chapter demonstrates application of the aqueous sol-gel method in
developing titania coatings on porous alumina substrates for controlling the poresize for
use as membrane elements in ultrafiltration. Thin coatings having ~50 nm thickness and
transparency of ~90% developed on glass surface were tested successfully for self
cleaning applications.
Tennant,A; Dawoud,M M; Anderson,A P(Department of Electronics, April 27, 1994)
[+]
[-]
Abstract:
A genetic algorithm has been used for null steering in phased and
adaptive arrays . It has been shown that it is possible to steer the
array null s precisely to the required interference directions and to
achieve any prescribed null depths . A comparison with the results
obtained from the analytic solution shows the advantages of using
the genetic algorithm for null steering in linear array patterns
Ravindranathan, S; Dr.Unnikrishnan, A(Cochin University of Science & Technology, October , 1991)
[+]
[-]
Abstract:
Neural Network has emerged as the topic of the day.
The spectrum of its application is as wide as from ECG noise
filtering to seismic data analysis and from elementary
particle detection to electronic music composition. The
focal point of the proposed work is an application of a
massively parallel connectionist model network for detection
of a sonar target. This task is segmented into: (i) generation of training patterns from sea noise that
contains radiated noise of a target, for teaching the
network;(ii) selection of suitable network topology and learning
algorithm and (iii) training of the network and its subsequent testing
where the network detects, in unknown patterns applied
to it, the presence of the features it has already
learned in. A three-layer perceptron using backpropagation
learning is initially subjected to a recursive training
with example patterns (derived from sea ambient noise with
and without the radiated noise of a target). On every
presentation, the error in the output of the network is
propagated back and the weights and the bias associated with
each neuron in the network are modified in proportion to
this error measure. During this iterative process, the network converges and extracts the target features which get
encoded into its generalized weights and biases.In every unknown pattern that the converged
network subsequently confronts with, it searches for the
features already learned and outputs an indication for their
presence or absence. This capability for target detection is
exhibited by the response of the network to various test
patterns presented to it.Three network topologies are tried with two
variants of backpropagation learning and a grading of the
performance of each combination is subsequently made.
Description:
Department of Electronics, Cochin University of Science and Technology
Tina, Sebastian; Dr. Sudha Kartha, C; Dr. Vijayakumar, K P(Cochin University of Science & Technology, August , 2009)
[+]
[-]
Abstract:
Aim of the present work was to automate CSP process, to deposit and
characterize CuInS2/In2S3 layers using this system and to fabricate devices using
these films.An automated spray system for the deposition of compound
semiconductor thin films was designed and developed so as to eliminate the manual
labour involved in spraying and facilitate standardization of the method. The system
was designed such that parameters like spray rate, movement of spray head, duration
of spray, temperature of substrate, pressure of carrier gas and height of the spray head
from the substrate could be varied. Using this system, binary, ternary as well as
quaternary films could be successfully deposited.The second part of the work deal with deposition and characterization of
CuInS2 and In2S3 layers respectively.In the case of CuInS2 absorbers, the effects of
different preparation conditions and post deposition treatments on the optoelectronic,
morphological and structural properties were investigated. It was observed
that preparation conditions and post deposition treatments played crucial role in controlling the properties of the films. The studies in this direction were useful in
understanding how the variation in spray parameters tailored the properties of the
absorber layer. These results were subsequently made use of in device fabrication
process.Effects of copper incorporation in
In2S3 films were investigated to find how the diffusion of Cu from CuInS2 to In2S3
will affect the properties at the junction. It was noticed that there was a regular
variation in the opto-electronic properties with increase in copper concentration.Devices were fabricated on ITO coated glass using CuInS2 as absorber and
In2S3 as buffer layer with silver as the top electrode. Stable devices could be
deposited over an area of 0.25 cm2, even though the efficiency obtained was not high.
Using manual spray system, we could achieve devices of area 0.01 cm2 only. Thus
automation helped in obtaining repeatable results over larger areas than those
obtained while using the manual unit. Silver diffusion on the cells before coating the
electrodes resulted in better collection of carriers.From this work it was seen CuInS2/In2S3 junction deposited through
automated spray process has potential to achieve high efficiencies.
Description:
Department of Physics,
Cochin University of Science and Technology
Mohanan,P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
[+]
[-]
Abstract:
A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed.
This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also
improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find
practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio
astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna
characteristics
Mohanan,P; Pravinkumar,P A; K G Nair(Indian Journal of Radio & Space Physics, 1982)
[+]
[-]
Abstract:
A simple technique for obtaining identical E- and H-plane patterns from E-plane sectoral feed horn is presented. Halfpower
beam width and gain of the antenna are also improved considerably. Experimental results for a number of horns with
flanges of various parameters are also presented. This system may find practical application in radar and space communication
systems