Babita Roslind, Jose; Dr.Mythili, P(Cochin University of Science & Technology, January , 2010)
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Abstract:
Analog-to digital Converters (ADC) have an important impact on the overall performance of signal processing system. This research is to explore efficient techniques for the design of sigma-delta ADC,specially for multi-standard wireless tranceivers. In particular, the aim is to develop novel models and algorithms to address this problem and to implement software tools which are avle to assist the designer's decisions in the system-level exploration phase. To this end, this thesis presents a framework of techniques to design sigma-delta analog to digital converters.A2-2-2 reconfigurable sigma-delta modulator is proposed which can meet the design specifications of the three wireless communication standards namely GSM,WCDMA and WLAN. A sigma-delta modulator design tool is developed using the Graphical User Interface Development Environment (GUIDE) In MATLAB.Genetic Algorithm(GA) based search method is introduced to find the optimum value of the scaling coefficients and to maximize the dynamic range in a sigma-delta modulator.
Description:
School of Engineering, Cochin University of Science and Technology
Sunil, Thomas; Dr.Balasundaran, M(Cochin University of Science And Technology, June , 2000)
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Abstract:
Spike disease in sandal is generally diagnosed by the manifestation of
external symptoms. Attempts have been made to detect the diseased plants
by determining the length/breadth ratio of leaves (lyengar, 1961) and
histochemical tests using Mann's stain (Parthasarathi et al., 1966), Dienes'
stain (Ananthapadmanabha et a/., 1973) aniline blue and Hoechst 33258
(Ghosh et a/., 1985, Rangaswamy, 1995). But most of these techniques are
insensitive, indirect detection methods leading to misinterpretation of results.
Moreover, to identify disease resistant sandal trees, highly sensitive
techniques are needed to detect the presence of the pathogen. In sandal
forests, several host plants of sandal like Zizyphus oenop/ea (Fig. 1.3) also
exhibit the yellows type disease symptoms. Immunological and molecular
assays have to be developed to confirm the presence of sandal spike
phytoplasma in such hosts. The major objectives of the present work
includes:In situ detection of sandal spike phytoplasma by epifluorescence
microscopy and scanning electron microscopy.,Purification of sandal spike phytoplasma and production of polyclonal antibodies.,Amino acid and total protein estimation of sandal spike phytoplasma.,Immunological detection of sandal spike phytoplasma.,
Molecular detection of sandal spike phytoplasma.,Screening for phytoplasma in host plants of spike disease affected sandal using immunological and molecular techniques.
Description:
Department of environmental studies, Cochin University of Science And Technology
Thomas, Varghese; Dr.Moli,P Koshy(Cochin University Of Science And Technology, April , 2013)
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Abstract:
This research work was to study the level of awareness of consumers
about health insurance concept and market, consumer perceptions about
health insurance providers, schemes and various factors that influence
buying decision of health insurance.
There is need to bring entire age group – high risk and low risk under
health insurance cover. Widening the cover of health insurance calls for indepth
understanding of consumer thinking and extensive marketing efforts
based on that. Hence the study of consumer perceptions and the impact of
different contributing factors on consumer purchase decision assume
significance to the marketer. Understanding the consumer thinking on
health insurance will also be of relevance to governmental/non
governmental agencies, as affordable health care to all is a policy objective
of the government and new schemes are being launched in this area.
Description:
School of Management 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
Binu, Paul; Dr.Mohanan, P(Cochin University of Science & Technology, September , 2005)
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Abstract:
The thesis explores the outcome of the exhaustive theoretical and experimental investigations performed on Octagonal Microstrip Antenna configurations. Development of the MATLAB TM backed 3D-Conformal Finite Difference Time Domain (CFDTD)Modeller for the numerical computation of the radiation characteristics of the antenna is the theme of the work. The predicted results are verified experimentally and by IE3D TM simulation. The influence of the patch dimensions,feed configurations,feed dimensions and feed positions upon the radiation performance of the antenna is studied in detail. Octagonal Microstrip Antenna configurations suitable for Mobile-Bluetooth application is dealt in detail. A simple design formula for the regular Octagonal geometry is also presented. A compact planar multi band antenna for GPS/DCS/2.4/5.8GHz WLAN application is included as appendix A. Planar near field measurement technique is explained in appendix B.
Description:
Department of Electroncis,
Cochin University of Science and Technology
Lethakumary,B; Dr.Mohanan, P(Cochin University of Science & Technology, December , 2004)
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Abstract:
The thesis is the outcome of the experimental and
theoretical Investigations on novel feeding
techniques for bandwidth enhancement of
microstrip patches. The new feeding techniques
provide bandwidth enhancement without
deteriorating the radiation characteristics of the
antenna. The antenna is analysed using finite
Difference Time Domain (FDTD) method. The
predicated results are compared with the
experimental results and excellent agreement is
observed. The results are also verified using IE3D
simulation software. The antenna is suitable for
personal and broadband communications.
Description:
Dept.of Electronics, Cochin University of Science and Technology
Rajesh, M V; Dr.Gopikakumari, R; Dr.Unnikrishnan, A(Cochin University of Science & Technology, December , 2010)
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Abstract:
Identification and Control of Non‐linear dynamical systems are challenging problems to the control engineers.The topic is equally relevant in communication,weather prediction ,bio medical systems and even in social systems,where nonlinearity is an integral part of the system behavior.Most of the real world systems are nonlinear in nature and wide applications are there for nonlinear system identification/modeling.The basic approach in analyzing the nonlinear systems is to build a model from known behavior manifest in the form of system output.The problem of modeling boils down to computing a suitably parameterized model,representing the process.The parameters of the model are adjusted to optimize a performanace function,based on error between the given process output and identified process/model output.While the linear system identification is well established with many classical approaches,most of those methods cannot be directly applied for nonlinear system identification.The problem becomes more complex if the system is completely unknown but only the output time series is available.Blind recognition problem is the direct consequence of such a situation.The thesis concentrates on such problems.Capability of Artificial Neural Networks to approximate many nonlinear input-output maps makes it predominantly suitable for building a function for the identification of nonlinear systems,where only the time series is available.The literature is rich with a variety of algorithms to train the Neural Network model.A comprehensive study of the computation of the model parameters,using the different algorithms and the comparison among them to choose the best technique is still a demanding requirement from practical system designers,which is not available in a concise form in the literature.The thesis is thus an attempt to develop and evaluate some of the well known algorithms and propose some new techniques,in the context of Blind recognition of nonlinear systems.It also attempts to establish the relative merits and demerits of the different approaches.comprehensiveness is achieved in utilizing the benefits of well known evaluation techniques from statistics. The study concludes by providing the results of implementation of the currently available and modified versions and newly introduced techniques for nonlinear blind system modeling followed by a comparison of their performance.It is expected that,such comprehensive study and the comparison process can be of great relevance in many fields including chemical,electrical,biological,financial and weather data analysis.Further the results reported would be of immense help for practical system designers and analysts in selecting the most appropriate method based on the goodness of the model for the particular context.
Description:
Division of Electronics Engineering,
School of Engineering,
Cochin University of Science & Technology
Laila, D; Dr.Mohanan, P(Cochin University of Science And Technology, October , 2012)
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Abstract:
Antennas, the key element in wireless communication devices had
undergone amazing developments especially in the direction of compactness
and safety aspects. In the last two decades, the use of the cellular phones has
become the most popular mode of communication across the globe. At the same
time, the concerns about the radiation effects have increased in the general
public. The main concern of this thesis is to develop a mobile antenna which
gives reduced RF interference to the user. The reduction of the power absorbed
by the user can tremendously avoid any possible health hazards.
The radiation characteristic of a monopole antenna is modified with good
radiation characteristics suitable for a mobile handset. The modification is
implemented by using different resonating structures which provides reduced
radiation along one direction. The direction of less radiation can be changed by
modifying the planar antenna structure to a ground folded antenna. This
modified structure with excellent radiation characteristic is suitable for modern
wireless handheld devices with less user RF interference. Specific Absorption
Rate (SAR) is an important parameter for mobile handset. The SAR is
estimated for the newly developed antenna for different conditions and
discussed in this thesis.
Description:
Department of Electronics, Cochin University of Science And Technology