Sony, George; Dr.V P N Nampoori(Cochin University of Science & Technology, September , 2011)
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Abstract:
The present thesis report the results obtained from the studies carried out on the
laser blow off plasma (LBO) from LiF-C (Lithium Fluoride with Carbon) thin film
target, which is of particular importance in Tokamak plasma diagnostics. Keeping
in view of its significance, plasma generated by the irradiation of thin film target by
nanosecond laser pulses from an Nd:YAG laser over the thin film target has been
characterized by fast photography using intensified CCD. In comparison to other
diagnostic techniques, imaging studies provide better understanding of plasma
geometry (size, shape, divergence etc) and structural formations inside the plume
during different stages of expansion.
Description:
International School of Photonics,Cochin University of Science and Technology
Vinayakan, R; Dr. George Thomas, K(National Institute for Interdisciplinary Science and Technology,CSIR, May , 2009)
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Abstract:
The overall focus of the thesis involves the synthesis and
characterization of CdSe QDs overcoated with shell materials for various
biological and chemical sensing applications. Second chapter deals with the
synthesis and characterization of CdSe and CdSe/ZnS core shell QDs. The
primary attention of this work is to develop a simple method based on
photoinduced charge transfer to optimize the shell thickness. Synthesis of
water soluble CdSe QDs, their cytotoxicity analysis and investigation of
nonlinear optical properties form the subject of third chapter. Final chapter
deals with development of QD based sensor systems for the selective
detection of biologically and environmentally important analytes from
aqueous media.
Sony, George; Ajai, Kumar; Singh, R K; Nampoori, V P N(American Institute of Physics, 2009)
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Abstract:
The dynamics of plasma plume, formed by the laser-blow-off of multicomponent LiF-C thin film
under various ambient pressures ranging from high vacuum to argon pressure of 3 Torr, has been
studied using fast imaging technique. In vacuum, the plume has ellipsoidal shape. With the increase
in the ambient pressure, sharp plume boundary is developed showing a focusing-like confinement
in the lateral space behavior in the front end, which persists for long times. At higher ambient
pressure (> 10−1 Torr ), structures are developed in the plasma plume due to hydrodynamic
instability/turbulences.
Gopikakumari, R; Dr.Sreedhar, C S(Cochin University Of Science And Technology, July 31, 1998)
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Abstract:
This thesis is an outcome of the investigations carried out on the development of an
Artificial Neural Network (ANN) model to implement 2-D DFT at high speed. A new
definition of 2-D DFT relation is presented. This new definition enables DFT computation
organized in stages involving only real addition except at the final stage of computation. The
number of stages is always fixed at 4. Two different strategies are proposed. 1) A visual
representation of 2-D DFT coefficients. 2) A neural network approach.
The visual representation scheme can be used to compute, analyze and manipulate 2D
signals such as images in the frequency domain in terms of symbols derived from 2x2
DFT. This, in turn, can be represented in terms of real data. This approach can help analyze
signals in the frequency domain even without computing the DFT coefficients.
A hierarchical neural network model is developed to implement 2-D DFT. Presently,
this model is capable of implementing 2-D DFT for a particular order N such that ((N))4 = 2.
The model can be developed into one that can implement the 2-D DFT for any order N upto a
set maximum limited by the hardware constraints. The reported method shows a potential in
implementing the 2-D DF T in hardware as a VLSI / ASIC
Description:
Department of Electronics,
Cochin University of Science and Technology