| Abstract: | This thesis addresses one of the emerging topics in Sonar Signal Processing.,viz.the implementation of a target classifier for the noise sources in the ocean, as the operator assisted classification turns out to be tedious,laborious and time consuming.In the work reported in this thesis,various judiciously chosen components of the feature vector are used for realizing the newly proposed Hierarchical Target Trimming Model.The performance of the proposed classifier has been compared with the Euclidean distance and Fuzzy K-Nearest Neighbour Model classifiers and is found to have better success rates.The procedures for generating the Target Feature Record or the Feature vector from the spectral,cepstral and bispectral features have also been suggested.The Feature vector ,so generated from the noise data waveform is compared with the feature vectors available in the knowledge base and the most matching pattern is identified,for the purpose of target classification.In an attempt to improve the success rate of the Feature Vector based classifier,the proposed system has been augmented with the HMM based Classifier.Institutions where both the classifier decisions disagree,a contention resolving mechanism built around the DUET algorithm has been suggested. |
| Description: | Departement of Electronics,Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2481 |
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| Dyuthi-T0664.pdf | (12.19Mb) |
| Abstract: | The dynamic mechanical properties such as storage modulus, loss modulus and damping properties of blends of nylon copolymer (PA6,66) with ethylene propylene diene (EPDM) rubber was investigated with special reference to the effect of blend ratio and compatibilisation over a temperature range –100°C to 150°C at different frequencies. The effect of change in the composition of the polymer blends on tanδ was studied to understand the extent of polymer miscibility and damping characteristics. The loss tangent curve of the blends exhibited two transition peaks, corresponding to the glass transition temperature (Tg) of individual components indicating incompatibility of the blend systems. The morphology of the blends has been examined by using scanning electron microscopy. The Arrhenius relationship was used to calculate the activation energy for the glass transition of the blends. Finally, attempts have been made to compare the experimental data with theoretical models. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1998 |
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| Dynamic mechanical analysis...pdf | (518.2Kb) |
| Abstract: | We report unusual spectral narrowing and laser emission from polymer thin films doped with Coumarin 540 dye. The laser emission from the polymer films is found to be highly dependent upon the excitation length of the medium. Even a short length of 1.75 mm of the dye doped film gave rise to laser emission with FWHM of 0.3 nm for a pump intensity of 825 kW cm−2. The partial reflections from the broad lateral surfaces of the free standing films provided the optical feedback for the laser emission. Occurrence of well-resolved equally spaced resonant modes confirmed the effect of a Fabry–Perot-like optical cavity between the film surfaces. |
| URI: | http://dyuthi.cusat.ac.in/purl/2420 |
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| Dyuthi-P0267.pdf | (421.1Kb) |
| Abstract: | Even though continental margins cover only about 7–9% of the world ocean area, they are important sites for organic carbon accumulation and hence play a major role in biogeochemical carbon cycling. Surface sediments from the western and eastern continental shelves of India were studied for their total organic matter content and the labile constituents such as total carbohydrates and proteins to get a better understanding of the hydrological and biogeochemical differences of the two regions on the nature of organic matter reaching the surface sediments. The sampling along the west coast was done during September–October 2003, when upwelling signatures were found to be still persisting along the shelf as evidenced by the low-oxygenated, nutrient-rich surface waters. The eastern shelf was sampled during November–December 2002. The shelf was found to be oxygen saturated and oligotrophic during the season. The surface sediments of the west coast contained a greater quantity of total organic matter when compared to the east coast, but the percentages of labile constituents of total organic matter in the sediments were found to be higher in the east coast by a factor of three as compared to the west coast. The differences in the productivity patterns and the hydrographical conditions were found to exert a major influence on the quantity and composition of organic matter in the surface sediments of the western and eastern continental shelves of India. |
| URI: | http://hdl.handle.net/purl/1888 |
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| Biogeochemistry ... diments of the Western.pdf | (479.2Kb) |
| Abstract: | A comparative study of two biopolymer based fiber optic humidity sensors is presented in this paper. Sensing elements Agarose and Chitosan swells in the presence of water vapour and undergoes changes in refractive index and modulates the intensity of light propagating through a fiber with Agarose or Chitosan as cladding. |
| URI: | http://dyuthi.cusat.ac.in/purl/2590 |
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| Dyuthi-P0150.pdf | (563.6Kb) |
| Abstract: | During an interstitial faunal survey along the south-west coast of Kerala, India, gastrotrich fauna were found in abundance. Together with species of the genera Xenotrichula, Halichaetonotus and Tetranchyroderma, were present several undescribed thaumastodermatid gastrotrichs belonging to the buccal palp bearing genus Pseudostomella. Adults of the new species are characterized by the following traits: total body length of about 300 μm; cuticular armature made up of medium sized pentancres covering the entire dorsolateral surface; pre-buccal, grasping palps bearing five, large papillae dorsally and 4-6 smaller papillae ventrally; adhesive apparatus made up of six anterior, 22-24 ventrolateral, two dorsolateral and six posterior adhesive tubes; caudal organ pear-shaped; frontal organ spherical. Pseudostomella cheraensis sp. nov. is the fourth taxon of the genus known from India; however, all the previous species reported hitherto from India have tetrancres instead of pentancres. |
| URI: | http://hdl.handle.net/purl/1890 |
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| A new species of Pseudostomella (Gastrotricha.pdf | (3.938Mb) |
| Abstract: | Highly conductive and transparent thin films of amorphous zinc indium tin oxide are prepared at room temperature by co-sputtering of zinc 10 oxide and indium tin oxide. Cationic contents in the films are varied by adjusting the power to the sputtering targets. Optical transmission study of 11 films showed an average transmission greater than 85% across the visible region. Maximum conductivity of 6×102 S cm−1 is obtained for Zn/In/ 12 Sn atomic ratio 0.4/0.4/0.2 in the film. Hall mobility strongly depends on carrier concentration and maximum mobility obtained is 18 cm2 V−1 s−1 13 at a carrier concentration of 2.1×1020 cm−3. Optical band gap of films varied from 3.44 eV to 3 eV with the increase of zinc content in the film 14 while the refractive index of the films at 600 nm is about 2.0. |
| URI: | http://dyuthi.cusat.ac.in/purl/792 |
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| TSF_24084.pdf | (673.9Kb) |
| Abstract: | Stable, OH free zinc oxide (ZnO) nanoparticles were synthesized by hydrothermal method by varying the growth temperature and concentration of the precursors. The formation of ZnO nanoparticles were confirmed by x-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies. The average particle size have been found to be about 7-24 nm and the compositional analysis is done with inductively coupled plasma atomic emission spectroscopy (ICP-AES). Diffuse reflectance spectroscopy (DRS) results shows that the band gap of ZnO nanoparticles is blue shifted with decrease in particle size. Photoluminescence properties of ZnO nanoparticles at room temperature were studied and the green photoluminescent emission from ZnO nanoparticles can originate from the oxygen vacancy or ZnO interstitial related defects. |
| URI: | http://dyuthi.cusat.ac.in/purl/790 |
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| Synthesis of Zn ... by hydrothermal method.pdf | (1.906Mb) |
| Abstract: | Transparent diode heterojunction on ITO coated glass substrates was fabricated using p-type AgCoO2 and n-type ZnO films by pulsed laser deposition (PLD). The PLD of AgCoO2 thin films was carried out using the pelletized sintered target of AgCoO2 powder, which was synthesized in-house by the hydrothermal process. The band gap of these thin films was found to be ~3.89 eV and they had transmission of~55% in the visible spectral region. Although Hall measurements could only indicate mixed carrier type conduction but thermoelectric power measurements of Seebeck coefficient confirmed the p-type conductivity of the grown AgCoO2 films. The PLD grown ZnO films showed a band gap of ~3.28 eV, an average optical transmission of ~85% and n-type carrier density of~4.6×1019 cm− 3. The junction between p-AgCoO2 and n-ZnO was found to be rectifying. The ratio of forward current to the reverse current was about 7 at 1.5 V. The diode ideality factor was much greater than 2. |
| URI: | http://dyuthi.cusat.ac.in/purl/791 |
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| Synthesis of Zn ... by hydrothermal method.pdf | (1.906Mb) |
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