Binoy, Paul; Dr.Girijavallabhan,C P(Cochin University of Science & Technology, February , 2004)
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Abstract:
Nonlinear optical processes in organic compounds have attracted considerable interest in the field of science and technology because of their compelling technological promises in fields of optical communication,computing,switching and signal processing.As a result of the synthesis of novel organic compounds with varying degree of nonlinear optical strength, many practical devices based on these are getting realised giving new theoretical insights into the nonolinear optical behaviour of materials.Organic compounds like phthalocyanines and porphyrins have evoked great deal of interest in the field of photonic technology.The present thesis describes the results obtained from the investigations carried out on the nonlinear optical properties of certain organo-metallic compounds using Z-Scan and DFWM techniques.
Description:
International School of Photonics,
Cochin University of Science & Technology
Mridula, S; Dr.Mohanan, P(Cochin University Of Science And Technology, July 7, 2005)
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Abstract:
The thesis relates to the investigations carried out on Rectangular Dielectric
Resonator Antenna configurations suitable for Mobile Communication applications.
The main objectives of the research are to:
- numerically compute the radiation characteristics of a Rectangular DRA
- identify the resonant modes
- validate the numerically predicted data through simulation and experiment
0 ascertain the influence of the geometrical and material parameters upon the
radiation behaviour of the antenna
° develop compact Rectangular DRA configurations suitable for Mobile
Communication applications
Although approximate methods exist to compute the resonant frequency of
Rectangular DRA’s, no rigorous analysis techniques have been developed so far to
evaluate the resonant modes. In this thesis a 3D-FDTD (Finite Difference Time
Domain) Modeller is developed using MATLAB® for the numerical computation of the radiation characteristics of the Rectangular DRA. The F DTD method is a
powerful yet simple algorithm that involves the discretimtion and solution of the
derivative form of Maxwell’s curl equations in the time domain.
Description:
Department of Electronics, Cochin University of Science and
Technology
Deepti Das, Krishna; Dr.Aanandan, C K(Cochin University of Science and Technology, September , 2010)
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Abstract:
In recent years, there is a visible trend for products/services which demand
seamless integration of cellular networks, WLANs and WPANs. This is a
strong indication for the inclusion of high speed short range wireless technology
in future applications. In this context UWB radio has a significant role
to play as an extension/complement to existing cellular/access technology.
In the present work, we have investigated two major types of wide band
planar antennas: Monopole and Slot. Four novel compact broadband antennas,
suitable for poratble applications, are designed and characterized, namely
1. Elliptical monopole
2. Inverted cone monopole
3. Koch fractal slot
4. Wide band slot
The performance of these designs have been studied using standard simulation
tools used in industry/academia and they have been experimentally verified.
Antenna design guidelines are also deduced by accounting the resonances in
each structure.
In addition to having compact sized, high efficiency and broad bandwidth
antennas, one of the major criterion in the design of impulse-UWB systems
have been the transmission of narrow band pulses with minimum distortion.
The key challenge is not only to design a broad band antenna with constant
and stable gain but to maintain a flat group delay or linear phase response
in the frequency domain or excellent transient response in time domain. One
of the major contributions of the thesis lies in the analysis of the frequency
and time-domain response of the designed UWB antennas to confirm their
suitability for portable pulsed-UWB systems. Techniques to avoid narrowband
interference by engraving narrow slot resonators on the antenna is also
proposed and their effect on a nano-second pulse have been investigated.
Description:
Department of Electronics,
Faculty of Technology,
Cochin University of Science and Technology
Suma,M N; Dr.Mohanan, P(Cochin University of Science & Technology, January , 2008)
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Abstract:
The space constraints on wireless gadgets is a challenge to antenna designers as the ground plane dimensions of the printed monopole significantly affect s the antenna characteristics.Investigations on ground plane truncations have led to the development of an extremely broad band printed monopole antenna.Omnidirectional radiation characteristics with moderate gain makes this antenna highly suitable for mobile/wireless applications .This thesis also highlights the development of UWB printed antenna along with design equations .Optimum ground plane dimensions for compact antenna applications,folding technique for miniaturization and double folding for dual band application are the other highlights of this thesis.
Description:
Department of Electronics,
Cochin University of Science and Technology
Mathiazhagan, A; Dr.Rani,Joseph; Dr.Narayanan, K P(Cochin University of Science & Technology, January , 2011)
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Abstract:
Brasses are widely used as constructional materials in marine environment due to their anticorrosive,antifouling and mechanical properties.However, its resistance to corrosion and fouling may vary according to local marine environmental condition and the seasons.The dezincification of brass is one of the forms of selective corrosion which has attracted the attention of researchers for the last two decades.Many of the dezincification mechanistic studies have been performed in noncomplex media and hence their conclusions cannot be extended to esturine water,which is of great significance since brass is extensively used in marine environment.Inhibited α brasses are largely immune to dezincication and the effect of tin and arsenic addition to α/beta brasses is not so reliable in controlling the dezincification. There have been many cases of dezincification in duplex brasses in both freshwater and seawater.Though there is some protection methods such as inhibitors,electro deposition and electro polymerization,there is no reliable method of inhibiting the dezincification of two-phase brass.Organic coatings are effectively used for the protection metals due to their capacity to act a physical barrieer between the metal surface and corrosive environment.Hence,pure epoxy coating is selected for this as it has antocorrosiion effect on brass.The dezincification behaviour of brass of the present study has been highlighted in terms of corrosion rate,weight gain/loss,corrosion current and polarization resistence,open circuit potential,dezincification factor. The marine fouling as biomass on brass was assessed and presented in this thesis, The physicochemical properties of estuarine water were correlated with corrosion behaviour of brass.The deterioration of the brass subjected to the effect of estuarine water was also investigated as a measure of loss in mechanical properties such as tensile strength,yield strength,percntage elongation and percentage reduction in area.To validate dezincification data,visual observation,spot analysis,surface morphology before and after removal of corrosion products and corrosion product analysis were performed.The dezincification behavior of epoxy coated brass of the present study has beenhighlighted in terms of corrosion rate ,weight gain/loss,corrosion current and polarization resistance,open circuit potential.dezincification factor.The marine fouling as biomass on epoxy coated brass subjeted to the effect of estuarine water was also investigated as ameasure of loss in mechanical properties such as tensile strength,percentage elongation and percentage reduction in area.The results of dezincification behavior of brass and epoxy coated brass in Cochin estuary water has been presented and discussed.Attempt has been made to correlate the dezincification behavior of brass with epoxy coated brass.
Description:
Dept.of Ship Technology,Cochin University of Science and Technology
Abdul Khader, K M; Dr.Mohandas, A(Cochin University of Science & Technology, 1999)
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Abstract:
Instead of developing easily degradable, and low-priced insecticides, we are
going after highly sophisticated chemicals. Here, an attempt is being made to develop
safer formulations of insecticides of botanical origin.
Different parts of the plants were chosen based on their use in countryside and
villages The dried plant materials were extracted with petroleum ether, and were
applied on Tribolium castaneum. The results were statistically analysed.
The active principles from Croton tigilium and Leea sambucina, the most
potential plants, were isolated using Column Chromatography, TLC, and Hydrolysis.
The isolated principles were analysed spectroscopically ( UV-Vis., IR, NMR,
and MS ) to identify their chemical nature. The active principles from Leea and
Croton were identified as a cholisterate derivative and a phorbol derivative
respectively.
In order to ascertain the environmental combatibility of the principles,
degradation by soil bacteria was studied.
The isolated principles were made into three type of formulations using
stabilizers .The formulations were applied on Snake gourd semilooper, Pulse beetle,
and mosquito larvae. Also the biocidal activity of the formulations was studied.
Both Leea derivative and Croton derivative could be formulated effectively
and were effective against a variety of pests. They are eco-friendly, as there is no
artificial chemicals involved.
Description:
School of Environmental Studies,
Cochin University of Science And Technology