Deepu, V; Dr. Mohanan, P(Cochin University of Science & Technology, April , 2009)
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Abstract:
Antennas are indispensable component of any wireless communication
device. An antenna is a transducer between the transmitter
and the free space waves and vice versa. They efficiently transfer
electromagnetic energy from a transmission line into free space.
But the present day communication applications require compact and ultra wide band designs which cannot be catered by simple microstrip based designs. PIFAs have solved the
problem to some extend, but the field of antennas needs more innovative designs
In this thesis the design and development of compact planner antenna are
presented. Emphasis is given to the design of the feed as well as the radiator
resulting in simple compact uniplanar geometries. The Asymmetric coplanar
feed used to excite the antennas is found to be a suitable choice for feeding compact antennas.The main objectives of the study are the design of compact single, dual and multi band antennas with uniplanar
structure and extension of the design for practical GSM/WLAN
applications and Ultra compact antennas using the above techniques and
extension of the design to antennas for practical applications like
RFID/DVB-H. All the above objectives are thoroughly studied. Antennas with ultra
compact dimensions are obtained as a result of the study. Simple equations are
provided to design antennas with the required characteristics. The design equations are verified by designing different antennas for different applications.
Description:
Department of Electronics, Cochin University of Science and Technology
Arun, V; Dr. Mohammed Yusuff, K K(Cochin University of Science & Technology, June , 2009)
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Abstract:
The thesis deals with studies on the synthesis, characterisation and catalytic
applications of some new transition metal complexes of the Schiff bases derived from 3-hydroxyquinoxaline 2-carboxaldehyde.. Schiff bases which are considered as ‘privileged ligands’ have the ability to stabilize different metals in different oxidation states and thus regulate the performance of metals in a large variety of catalytic transformations. The
catalytic activity of the Schiff base complexes is highly dependant on the environment about
the metal center and their conformational flexibility. Therefore it is to be expected that the
introduction of bulky substituents near the coordination sites might lead to low symmetry complexes with enhanced catalytic properties. With this view new transition metal
complexes of Schiff bases derived from 3-hydroxyquinoxaline-2-carboxaldehyde have been
synthesised. These Schiff bases have more basic donor nitrogen atoms and the presence of
the quinoxaline ring may be presumed to build a favourable topography and electronic
environment in the immediate coordination sphere of the metal. The aldehyde was condensed
with amines 1,8-diaminonaphthalene, 2,3-diaminomaleonitrile, 1,2-diaminocyclohexane,
2-aminophenol and 4-aminoantipyrine to give the respective Schiff bases. The oxovanadium(IV), copper(II) and ruthenium(II)complexes of these Schiff bases were synthesised and characterised.
All the oxovanadium(IV) complexes have binuclear structure with a square pyramidal geometry.
Ruthenium and copper form mononuclear complexes with the Schiff base derived from 4-
aminoantipyrine while binuclear square planar complexes are formed with the other Schiff
bases. The catalytic activity of the copper complexes was evaluated in the hydroxylation of
phenol with hydrogen peroxide as oxidant. Catechol and hydroquinone are the major products. Catalytic properties of the oxovanadium(IV) complexes were evaluated in the
oxidation of cyclohexene with hydrogen peroxide as the oxidant. Here allylic oxidation
products rather than epoxides are formed as the major products. The ruthenium(II)
complexes are found to be effective catalysts for the hydrogenation of benzene and toluene.
The kinetics of hydrogenation was studied and a suitable mechanism has been proposed.
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology
Jayasree, V K; Dr. Radhakrishnan, P(Cochin University of Science and Technology, January , 2009)
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Abstract:
Photoplethysmography (PPG) is a simple and inexpensive optical
technique that can be used to detect blood volume changes in the
microvascular bed of tissues. There has been a resurgence of
interest in the technique in recent years, driven by the demand for low
cost, simple and portable technology for the primary care and
community based clinical settings and the wide availability of low cost
and small semiconductor components, and the advancement of
computer-based pulse wave analysis techniques. The present research work deals with the design of a PPG sensor for recording the
blood volume pulse signals and carry out selected cardiovascular studies based
on these signals. The interaction of light with tissue, early and recent history of PPG,
instrumentation, measurement protocol and pulse wave analysis are also discussed in this study. The effect of aging, mild cold exposure, and variation in the body posture on the PPG
signal have been experimentally studied.
Description:
International School of Photonics, Cochin University of Science and Technology