Sona, Narayanan; Rani, Joseph; Sreekumar, A; Sudha Kartha, C(Cochin University Of Science And Technology, February , 2015)
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Abstract:
The main focus of the present study was to develop ideal low band gap D-A copolymers for photoconducting and non-linear optical applications. This chapter summarizes the overall research work done. Designed copolymers were synthesized via direct arylation or Suzuki coupling reactions. Copolymers were characterized by theoretical and experimental methods. The suitability of these copolymers in photoconducting and optical limiting devices has been investigated.The results suggest that the copolymers investigated in the present study have a good non-linear optical response and are comparable to or even better than the D-A copolymers reported in the literature and hence could be chosen as ideal candidates with potential applications for non-linear optics. The results also show that the structures of the polymers have great impact on NLO properties. Copolymers studied here exhibits good optical limiting property at 532 nm wavelength due to two-photon absorption (TPA) process. The results revealed that the two copolymers, (P(EDOT-BTSe) and P(PH-TZ)) exhibited strong two-photon absorption and superior optical power limiting properties, which are much better than that of others.
Rekha, James K; Poulose Jacob,K; Sreela Sasi(Cochin University of Science and Technology, January , 2010)
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Abstract:
Most of the commercial and financial data are stored in decimal fonn. Recently, support for decimal arithmetic has received increased attention due to the growing importance in financial analysis, banking, tax calculation, currency conversion, insurance, telephone billing and accounting. Performing decimal arithmetic with systems that do not support decimal computations may give a result with representation error, conversion error, and/or rounding error. In this world of precision, such errors are no more tolerable. The errors can be eliminated and better accuracy can be achieved if decimal computations are done using Decimal Floating Point (DFP) units. But the floating-point arithmetic units in today's general-purpose microprocessors are based on the binary number system, and the decimal computations are done using binary arithmetic. Only few common decimal numbers can be exactly represented in Binary Floating Point (BF P). ln many; cases, the law requires that results generated from financial calculations performed on a computer should exactly match with manual calculations. Currently many applications involving fractional decimal data perform decimal computations either in software or with a combination of software and hardware. The performance can be dramatically improved by complete hardware DFP units and this leads to the design of processors that include DF P hardware.VLSI implementations using same modular building blocks can decrease system design and manufacturing cost. A multiplexer realization is a natural choice from the viewpoint of cost and speed.This thesis focuses on the design and synthesis of efficient decimal MAC (Multiply ACeumulate) architecture for high speed decimal processors based on IEEE Standard for Floating-point Arithmetic (IEEE 754-2008). The research goal is to design and synthesize deeimal'MAC architectures to achieve higher performance.Efficient design methods and architectures are developed for a high performance DFP MAC unit as part of this research.
Description:
Department of Computer Science, Cochin University of Science and Technology
Joseph,P M; Dr.Saseendran Pillai,P R(Cochin University of Science & Technology, May , 1992)
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Abstract:
Systems which employ underwater acoustic energy
for observation or communication are called sonar systems. The active and passive sonars are the two
types of systems used for the detection and localisation
of targets in underwater. Active sonar involves the
transmission of an acoustic signal which, when reflected
from a target, provides the sonar receiver with a basis
for the detection and estimation. Passive sonar bases
its detection and estimation on sounds which emanate
from the target itself--Machinery noise, flow noise,
transmission from its own active sonar etc.Electroacoustic transducers are used in sonar
systems for the transmission and detection of acoustic
energy. The transducer which is used for the transmission
of acoustic energy is called projector and the
one used for reception is called hydrophone. Since a
single transducer is not sufficient enough for long
range and directional transmission, a properly distributed
array of transducers are to be used [9-11].The need and requirement for spatial processing
to generate the most favourable directivity patterns for
transducer systems used in underwater applications have
already been analysed by several investigators [12-21].The desired directivity pattern can be either generated
by the use of suitable focussing techniques or by an
array of non-directional sensor elements, whose arrangements,
spacing and the mode of excitation provide the
required radiation pattern or by the combination of
these.While computing
that
the directivity pattern, it is
assumed strength of the elements are
unaffected by
the
the
source
acoustic pressure at each source.
However, in closely packed a r r a y s , the acoustic interaction
effects experienced among the elements will
modify the behaviour of individual elements and in turn
will reduce the acoust ic source leve 1 wi t h respect to
the maximum t heoret i cal va 1ue a s well as degrade the
beam pa t tern. Th i s ef fect shou 1d be reduced in systems
that are intended to generate high acoustic power output
and unperturbed beam patterns [2,22-31].The work herein presented includes an approach
for designing efficient and well behaved underwater
transd~cer arrays, taking into account the acoustic
interaction effect experienced among the closely packed
multielement arrays.Architectural modifications
reducing the interaction effect
different radiating apertures.
Description:
Department of Electronics, Cochin University
of Science and Technology.
Thomas Lee, S; Dr.Nampoori,V P N; Dr. Radhakrishnan, P(Cochin University of Science & Technology, May , 2003)
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Abstract:
Advent of lasers together with the advancement in fiber optics technology has revolutionized the sensor technology. Advancement in the telemetric applications of optical fiber based measurements is an added bonus. The present thesis describes variety of fiber based sensors using techniques like micro bending, long period grating and evanescent waves. Sensors to measure various physical and chemical parameters are described in this thesis.
Description:
International School of Photonics,
Cochin University of Science and Technology
Geetha, K; Radhakrishnan, P(International School of Photonics, June , 2006)
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Abstract:
The rapid developments in fields such as fibre optic communication
engineering and integrated optical electronics have expanded the interest and
have increased the expectations about guided wave optics, in which optical
waveguides and optical fibres play a central role. The technology of guided
wave photonics now plays a role in generating information (guided-wave
sensors) and processing information (spectral analysis, analog-to-digital
conversion and other optical communication schemes) in addition to its
original application of transmitting information (fibre optic communication).
Passive and active polymer devices have generated much research
interest recently because of the versatility of the fabrication techniques and
the potential applications in two important areas – short distant
communication network and special functionality optical devices such as
amplifiers, switches and sensors. Polymer optical waveguides and fibres are
often designed to have large cores with 10-1000 micrometer diameter to
facilitate easy connection and splicing.
Large diameter polymer optical fibres being less fragile and vastly
easier to work with than glass fibres, are attractive in sensing applications.
Sensors using commercial plastic optical fibres are based on ideas already
used in silica glass sensors, but exploiting the flexible and cost effective
nature of the plastic optical fibre for harsh environments and throw-away
sensors.
In the field of Photonics, considerable attention is centering on the
use of polymer waveguides and fibres, as they have a great potential to create
all-optical devices. By attaching organic dyes to the polymer system we can
incorporate a variety of optical functions. Organic dye doped polymer
waveguides and fibres are potential candidates for solid state gain media.
High power and high gain optical amplification in organic dye-doped
polymer waveguide amplifier is possible due to extremely large emission
cross sections of dyes. Also, an extensive choice of organic dye dopants is
possible resulting in amplification covering a wide range in the visible region.
Jayaprakash, P; Dr. Menon, A K(Cochin University of Science And Technology, March 15, 1999)
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Abstract:
A GIS has been designed with limited Functionalities; but with a novel approach in
Aits design. The spatial data model adopted in the design of KBGIS is the unlinked
vector model. Each map entity is encoded separately in vector fonn, without referencing
any of its neighbouring entities. Spatial relations, in other words, are not encoded. This
approach is adequate for routine analysis of geographic data represented on a planar map,
and their display (Pages 105-106). Even though spatial relations are not encoded
explicitly, they can be extracted through the specially designed queries.
This work was undertaken as an experiment to study the feasibility of developing a
GIS using a knowledge base in place of a relational database. The source of input spatial
data was accurate sheet maps that were manually digitised. Each identifiable geographic
primitive was represented as a distinct object, with its spatial properties and attributes
defined. Composite spatial objects, made up of primitive objects, were formulated, based
on production rules defining such compositions. The facts and rules were then organised
into a production system, using OPS5
Description:
Department of Computer Science
School of Computer Science Studies
Cochin University of Science and Technology
Rohith, Raj K; Dr.Mohanan, P(Cochin University of Science & Technology, August , 2007)
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Abstract:
The coplanar wave guide is an attractive device in microwave integrated
circuits due to its uniplanar nature, ease of fabrication and low production cost.
Several attempts are already done to explore the radiating modes in coplanar
wave guide transmission lines. Usually coplanar wave guides are excited by an
SMA connector with its centre conductor connected to the exact middle of the
centre strip and the outer ground conductor to the two ground strips. The mode
excited on it is purely a bound mode. The E-field distribution in the two slots are
out of phase and there for cancels at the far field. This thesis addresses an
attempt to excite an in phase E-field distribution in the two slots of the co planar
wave guide by employing a feed asymmetry, in order to get radiation from the two
large slot discontinuities of the coplanar waveguide. The omni directional
distribution of the radiating energy can be achieved by widening the centre strip.The first part of the thesis deals with the investigations on the resonance
phenomena of conventional coplanar waveguides at higher frequency bands.
Then an offset fed open circuited coplanar waveguide supporting
resonance/radiation phenomena is analyzed. Finally, a novel compact co planar
antenna geometry with dual band characteristics, suitable for mobile terminal
applications is designed and characterized using the inferences from the above
study.
Description:
Department of
Electronics, Cochin University of Science and Technology
Jacob,George; Dr.Mohanan, P(Cochin University of Science & Technology, June , 1998)
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Abstract:
The thesis is the outcome of the experimental and theoretical investigations on a new compact drum-shaped microstrip antenna. A new compact antenna suitable for personal communication system(PCS), Global position System(GPS) and array applications is developed and analysed. The generalised cavity model and spatial fourier transform technique are suitably modified for the analysis of the antenna. The predicted results are compared with experimental results and excellent agreement is observed. The experimental work done by the author in related fields are incorporated as three appendices in this thesis. A single feed dual frequency microstrip antenne is presented in appendix A.Appendix B describes a new broadband dual frequeny microstrip antenna. The bandwidth enhancement effect of microstrip antennas through dielectric resonator loading is demonstarted in Appendix C.
Description:
Department of Electronics,
Cochin University of Science and Technology
Gopakumar,C; Dr.Mathew, K T(Cochin University of Science and Technology, January , 2011)
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Abstract:
This thesis describes the development and analysis of an Isosceles Trapezoidal
Dielectric Resonator Antenna (ITDRA) by realizing different DR orientations with
suitable feed configurations enabling it to be used as multiband, dual band dual
polarized and wideband applications.
The motivation for this work has been inspired by the need for compact, high
efficient, low cost antenna suitable for multi band application, dual band dual polarized
operation and broadband operation with the possibility of using with MICs, and to
ensure less expensive, more efficient and quality wireless communication systems. To
satisfy these challenging demands a novel shaped Dielectric Resonator (DR) is
fabricated and investigated for the possibility of above required properties by trying out
different orientations of the DR on a simple microstrip feed and with slotted ground
plane as well.
The thesis initially discusses and evaluates recent and past developments taken
place within the microwave industry on this topic through a concise review of
literature. Then the theoretical aspects of DRA and different feeding techniques are
described. Following this, fabrication and characterization of DRA is explained.
To achieve the desired requirements as above both simulations and
experimental measurements were undertaken. A 3-D finite element method (FEM)
electromagnetic simulation tool, HFSSTM by Agilent, is used to determine the optimum
geometry of the dielectric resonator. It was found to be useful in producing
approximate results although it had some limitations. A numerical analysis technique,
finite difference time domain (FDTD) is used for validating the results of wide band
design at the end. MATLAB is used for modeling the ITDR and implementing FDTD
analysis.
In conclusion this work offers a new, efficient and relatively simple alternative
for antennas to be used for multiple requirements in the wireless communication
system.
Description:
Department of Electronics, Cochin
University of Science and Technology
Sona,Kundukulam O; Dr.Aanandan, C K(Cochin University of Science and Technology, June , 2002)
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Abstract:
The practical applications of microstrip antennas for mobile systems are in
portable or pocket-size equipment and in vehicles. Antennas for VHFIUHF handheld
portable equipment, such as pagers, portable telephones and transceivers,
must naturally be small in size, light in weight and compact in structure. There is
a growing tendency for portable equipment to be made smaller and smaller as the
demand for personal communication rapidly increases, and the development of
very compact hand-held units has become urgent.In this thesis work, main aim is to develop a more and more reduced sized
microstrip patch antenna. It is well known that the smaller the antenna size, the
lower the antenna efficiency. During the period of work, three different compact
circular sided microstrip patches are developed and analysed, which have a
significant size reduction compared to standard circular disk antenna (the most
compact one of the basic microstrip patch configurations), without much
deterioration of its properties like gain, bandwidth and efficiency. In addition to
this the interesting results, dual port operation and circular polarization are also
observed for some typical designs of these patches. These make the patches
suitable for satellite and mobile communication systems.The theoretical investigations are carried out on these compact patches. The
empirical relations are developed by modifying the standard equations of
rectangular and circular disk microstrip patches, which helps to predict the
resonant frequencies easily.
Description:
Department of
Electronics, Cochin University of Science and Technology