Sunny, Kuriakose; Dr.Abdul Rasheed, T M(Cochin University Of Science And Technology, October 7, 2003)
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Abstract:
Vibrational overtone spectroscopy of molecules containing X-H oscillators
(X = C, N, O...) has become an effective tool for the study of molecular structure,
dynamics, inter and intramolecular interactions, conformational aspects and
substituent effects in aliphatic and aromatic compounds. In the present work, the author studied the NIR overtone spectra of some liquid phase organic compounds. The analysis of the CH, NH and OH overtones yielded important structural
information about these systems. In an attempt to get information on electronic
energy levels, we studied the pulsed Nd:YAG laser induced fluorescence spectra
of certain organic compounds. The pulsed laser Raman spectra of some organic
compounds are also studied. The novel high resolution technique of near infrared
tunable diode laser absorption spectroscopy (TDLAS) is used to record the
rotational structure of the second OH overtone spectrum of 2-propanol. The
spectral features corresponding to the different molecular conformations could be
identified from the high resolution spectrum.
The whole work described in this thesis is divided into five chapters.
Description:
Department of Physics
Cochin University of Science and Technology
Sudha Kartha, C; Dr.Sathianandan, K(Cochin University of Science and Technology, February , 1984)
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Abstract:
The present study is mainly concéntrated on the visible
fluorescence of Ho3+ ,nd 3+ and Er 3+rare earths in
alkaline earth fluoride hosts(caF2,srF2,BaF2)
using a nitrogen laser excitation. A nitrogen laser was fabricated and its parametric studies were first carried out.
Description:
Department of Physics, Cochin University of Science and Technology
Paulraj,M; Dr.Vijayakumar, K P(Department of Physics, Faculty of Science, December , 2004)
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Abstract:
Materials and equipment which fail to achieve the design requirements or projected life due to undetected defects may require expensive repair or early replacement. Such defects may also be the cause of unsafe conditions or catastrophic unexpected failure, and will lead to loss of revenue due to plant shutdown. Non-Destructive Evaluation (NDE) / Non Destructive Testing (NDT) is used for the examination of materials and components without changing or destroying their usefulness. NDT can be applied to each stage of a system’s construction, to monitor the integrity of the system or structure throughout its life.
Poornima,N; Dr.Sudha Kartha,C(Cochin University Of Science And Technology, November , 2013)
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Abstract:
Photoluminescence (PL) spectroscopy is an optical technique that has
emerged successful in the field of semiconductor material and device
characterization. This technique is quite a powerful one which gives idea about
the defect levels in a material, the band gap of the material, composition as well
as material quality. Over the recent years it has received an elevation as a
mainstream characterization technique.
This thesis is an attempt to characterize each individual layer used in a thin
film solar cell with special focus on the electrical properties. This will be highly
beneficial from the lab as well as industrial point of view because electrical
measurements generally are contact mode measurements which tend to damage
the surface. As far as a thin film solar cell is concerned, the constituent layers are
the transparent conducting oxide (TCO), absorber layer, buffer layer and top
electrode contact. Each layer has a specific role to play and the performance of a
solar cell is decided and limited by the quality of each individual layer. Various
aspects of PL spectroscopy have been employed for studying compound
semiconductor thin films [deposited using chemical spray pyrolysis (CSP)]
proposed for solar cell application. This thesis has been structured in to seven
chapters
Description:
Applied Optics Division,
Department of Physics,
Cochin University of Science and Technology
Venugopalan, P; Dr.Nair, K G(Cochin University of Science and Technology, August , 1991)
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Abstract:
The motivatitni for" the present work is from .a
project sanctioned by TSRO. The work involved the development
of a quick and reliable test procedure using
microwaves, for tflue inspection of cured propellant samples
and a method to monitor the curing conditions of propellant
mix undergoing the curing process.Normal testing CHE the propellant samples involvecuttimg a piece from each carton and testing it for their tensile strength. The values are then compared with standard ones and based on this result the sample isaccepted or rejected. The tensile strength is a measure ofdegree of cure of the propellant mix. But this measurementis a destructive procedure as it involves cutting of the sample. Moreover, it does not guarantee against nonuniform curing due to power failure, hot air-line failure,operator error etc. This necessitated the need for the development of a quick and reliable non-destructive test
procedure.
Description:
Department of Electronics, Cochin University of Science and Technology
Jijo, P U; Dr.Nandakumaran,V M(Cochin University of Science & Technology, August , 2008)
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Abstract:
This thesis presents analytical and numerical results from studies based on the multiple
quantum well laser rate equation model. We address the problem of controlling chaos produced
by direct modulation of laser diodes. We consider the delay feedback control methods
for this purpose and study their performance using numerical simulation. Besides the control
of chaos, control of other nonlinear effects such as quasiperiodicity and bistability using
delay feedback methods are also investigated.A number of secure communication schemes based on synchronization of chaos semiconductor
lasers have been successfully demonstrated theoretically and experimentally. The current
investigations in these field include the study of practical issues on the implementations of
such encryption schemes. We theoretically study the issues such as channel delay, phase mismatch
and frequency detuning on the synchronization of chaos in directly modulated laser
diodes. It would be helpful for designing and implementing chaotic encryption schemes using
synchronization of chaos in modulated semiconductor lasers.
Description:
International School of Photonics,
Cochin university of Science & Technology
Parvathi, M R; Dr.Nandakumaran,V M(Cochin University of Science & Technology, May , 2009)
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Abstract:
In this thesis we have presented some aspects of the nonlinear dynamics of
Nd:YAG lasers including synchronization, Hopf bifurcation, chaos control
and delay induced multistability.We have chosen diode pumped Nd:YAG
laser with intracavity KTP crystal operating with two mode and three mode
output as our model system.Different types of orientation for the laser cavity
modes were considered to carry out the studies. For laser operating with two
mode output we have chosen the modes as having parallel polarization and
perpendicular polarization. For laser having three mode output, we have
chosen them as two modes polarized parallel to each other while the third
mode polarized orthogonal to them.
Description:
International School of Photonics,
Cochin University of Science and Technology
Rajesh, S; Nandakumaran, V M(International School of Photonics, January , 2005)
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Abstract:
Nonlinear dynamics of laser systems has become an interesting area of research in recent
times. Lasers are good examples of nonlinear dissipative systems showing many kinds of
nonlinear phenomena such as chaos, multistability and quasiperiodicity. The study of these
phenomena in lasers has fundamental scientific importance since the investigations on these
effects reveal many interesting features of nonlinear effects in practical systems. Further,
the understanding of the instabilities in lasers is helpful in detecting and controlling such
effects.
Chaos is one of the most interesting phenomena shown by nonlinear deterministic systems.
It is found that, like many nonlinear dissipative systems, lasers also show chaos for
certain ranges of parameters. Many investigations on laser chaos have been done in the last
two decades. The earlier studies in this field were concentrated on the dynamical aspects
of laser chaos. However, recent developments in this area mainly belong to the control
and synchronization of chaos. A number of attempts have been reported in controlling
or suppressing chaos in lasers since lasers are the practical systems aimed to operated in
stable or periodic mode. On the other hand, laser chaos has been found to be applicable in
high speed secure communication based on synchronization of chaos. Thus, chaos in laser
systems has technological importance also.
Semiconductor lasers are most applicable in the fields of optical communications among
various kinds of laser due to many reasons such as their compactness, reliability modest cost
and the opportunity of direct current modulation. They show chaos and other instabilities
under various physical conditions such as direct modulation and optical or optoelectronic
feedback. It is desirable for semiconductor lasers to have stable and regular operation.
Thus, the understanding of chaos and other instabilities in semiconductor lasers and their
xi
control is highly important in photonics.
We address the problem of controlling chaos produced by direct modulation of laser
diodes. We consider the delay feedback control methods for this purpose and study their
performance using numerical simulation. Besides the control of chaos, control of other
nonlinear effects such as quasiperiodicity and bistability using delay feedback methods are
also investigated.
A number of secure communication schemes based on synchronization of chaos semiconductor
lasers have been successfully demonstrated theoretically and experimentally. The
current investigations in these field include the study of practical issues on the implementations
of such encryption schemes. We theoretically study the issues such as channel delay,
phase mismatch and frequency detuning on the synchronization of chaos in directly modulated
laser diodes. It would be helpful for designing and implementing chaotic encryption
schemes using synchronization of chaos in modulated semiconductor laser
Elizabeth, C V; Dr. Sreekumar, K(Cochin University of Science and Technology, September 29, 2010)
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Abstract:
Present thesis has discussed the design and synthesis of polymers suitable for nonlinear optics. Most of the molecules that were studied have shown good nonlinear optical activity. The second order nonlinear optical activity of the polymers was measured experimentally by Kurtz and Perry powder technique. The thesis comprises of eight chapters.The theory of NLO phenomenon and a review about the various nonlinear optical polymers has been discussed in chapter 1. The review has provided a survey of NLO active polymeric materials with a general introduction, which included the principles and the origin of nonlinear optics, and has given emphasis to polymeric materials for nonlinear optics, including guest-host systems, side chain polymers, main chain polymers, crosslinked polymers, chiral polymers etc.Chapter 2 has discussed the stability of the metal incorporated tetrapyrrole molecules, porphyrin, chlorin and bacteriochlorin.Chapter 3 has provided the NLO properties of certain organic molecules by computational tools. The chapter is divided into four parts. The first part has described the nonlinear optical properties of chromophore (D-n-A) and bichromophore (D-n-A-A-n-D) systems, which were separated by methylene spacer, by making use of DPT and semiempirical calculations.Chapter 4: A series of polyurethanes was prepared from cardanol, a renewable resource and a waste of the cashew industry by previously designed bifunctional and multifunctional polymers using quantum theoretical approach.Chapter 5: A series of chiral polyurethanes with main chain bis azo diol groups in the polymer backbone was designed and NLO activity was predicted by ZlNDO/ CV methods.In Chapter 7, polyurethanes were first designed by computational methods and the NLO properties were predicted by correction vector method. The designed bifunctional and multifunctional polyurethanes were synthesized by varying the chiral-achiral diol compositions
Description:
Department of Applied Chemistry, Cochin University of Science and Technology
Daly, Davis; Dr. Sreekumar, K(Cochin University Of Science And Technology, September 12, 2005)
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Abstract:
The present work emphasizes the use of chirality as an efficient tool to synthesize
new types of second order nonlinear materials. Second harmonic generation efficiency
(SHG) is used as a measure of second order nonlinear response. Nonlinear optical
properties of polymers have been studied theoretically and experimentally. Polymers
were designed theoretically by ab initio and semiempirical calculations. All the
polymeric systems have been synthesized by condensation polymerization. Second
harmonic generation efficiency of the synthesized systems has been measured
experimentally by Kurtz and Perry powder method
Description:
Department of Applied Chemistry, Cochin University of Science and
Technology
Indic, P; Dr.Nampoori,V P N(Cochin University Of Science And Technology, November 1, 2000)
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Abstract:
Interfacings of various subjects generate new field ofstudy and research that
help in advancing human knowledge. One of the latest of such fields is
Neurotechnology, which is an effective amalgamation of neuroscience, physics,
biomedical engineering and computational methods. Neurotechnology provides a
platform to interact physicist; neurologist and engineers to break methodology and
terminology related barriers. Advancements in Computational capability, wider
scope of applications in nonlinear dynamics and chaos in complex systems enhanced
study of neurodynamics. However there is a need for an effective dialogue among
physicists, neurologists and engineers.
Application of computer based technology in the field of medicine through
signal and image processing, creation of clinical databases for helping clinicians etc
are widely acknowledged. Such synergic effects between widely separated
disciplines may help in enhancing the effectiveness of existing diagnostic methods.
One of the recent methods in this direction is analysis of electroencephalogram with
the help of methods in nonlinear dynamics. This thesis is an effort to understand the
functional aspects of human brain by studying electroencephalogram. The algorithms
and other related methods developed in the present work can be interfaced with a
digital EEG machine to unfold the information hidden in the signal. Ultimately this
can be used as a diagnostic tool.
Description:
International
School of Photonics, Cochin University of Science and Technology
Ansa Alphonsa, Antony; Dr.Sankaran, P G(Cochin University of Science and Technology, September 1, 2005)
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Abstract:
So far, in the bivariate set up, the analysis of lifetime (failure time) data with
multiple causes of failure is done by treating each cause of failure separately. with
failures from other causes considered as independent censoring. This approach is
unrealistic in many situations. For example, in the analysis of mortality data on
married couples one would be interested to compare the hazards for the same cause
of death as well as to check whether death due to one cause is more important for the
partners’ risk of death from other causes. In reliability analysis. one often has
systems with more than one component and many systems. subsystems and
components have more than one cause of failure. Design of high-reliability systems
generally requires that the individual system components have extremely high
reliability even after long periods of time. Knowledge of the failure behaviour of a
component can lead to savings in its cost of production and maintenance and. in
some cases, to the preservation of human life. For the purpose of improving
reliability. it is necessary to identify the cause of failure down to the component
level. By treating each cause of failure separately with failures from other causes
considered as independent censoring, the analysis of lifetime data would be
incomplete. Motivated by this. we introduce a new approach for the analysis of
bivariate competing risk data using the bivariate vector hazard rate of Johnson and
Kotz (1975).
Description:
Department of Statistics, Cochin University of Science and Technology
Sindhu,Mathai; Vijay Nair,G(Regional Research Laboratory(CSIR), 2004)
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Abstract:
The thesis entitled novel 1,3-dipolar cycloaddition reactions of acyclic carbonyl ylides and related chemistry embodies the results of the investigations carried out to explore the reactivity of acyclic carbonyl ylides,generated by the reaction of dicarbomethoxy carbine and aldehydes towards dipolarophiles such as activated styrenes,1,2-and 1,4-quinones. In conclusion ,we have explored the reactivity pattern of acyclic carbonyl ylides derived from dicarbomethoxycarbene and aldehyde towards activated styrenes with a view to develop a stereoselective synthesis of highly substituted tetrahydrofuran derivatives. It was also found that the ylide could be trapped by various 1,2-and 1,4-diones to form dioxolane derivatives. It is noteworthy that the cycloaddition is highly region- and stereoselective. With isatins the ylide preferentially adds to the more electrone deficient carbonyl group making it regiospecific. Hetrocyclic compounds are of pivotal importance in organic chemistry, and enormous efforts have been devoted to develop new methodologies for their synthesis. It is noteworthy in this context that, 1,3-dipolar cycloaddition reaction,otherwise called Huisgen reaction, constitutes one of the most efficient methods for the synthesis of five membered heterocycles. Among the various dipoles, carbonyl ylides have received substiancial attention in recent years largely due to their utility in the synthesis of a wide range of oxygen hetrocycles, which are often found as structural subunits of many bioactive natural products.