| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1986 |
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| Dyuthi-T0383.pdf | (4.776Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/2128 |
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| Dyuthi-T0488.pdf | (1.352Mb) |
| Abstract: | The aerosols in the atmosphere play major role in the radiation balance of the Earthatmosphere system. Direct and indirect impact of aerosols on the weather and climate still remains as a topic to be investigated in detail. The effect of aerosols on the radiation budget and thereby circulation pattern is important and requires further study. A detailed analysis of the aerosol properties, their variability and meteorological processes that affect the aerosol properties and distribution over the Indian region is performed in the thesis. The doctoral thesis entitled “Characteristics of aerosols over the Indian region and their variability associated with atmospheric conditions” contains 7 chapters. This thesis presents results on the analysis on the distribution (spatial and temporal) and characteristics of the aerosols over the Indian region and adjoining seas. Regional and stationwise data were analysed and methods such as modeling and statistical analysis are implemented to understand the aerosol properties, classification and transportation. Chapter-1 presents a brief introduction on the aerosols, their measurement techniques, impact of aerosols on the atmospheric radiation budget, climatic and geographic features of the study area and the literature review on the previous studies. It provides a basic understanding in the field of study and objective of the thesis. Definition of the aerosols, their sources/sinks and classification of the particles according to optical and microphysical properties are described. Different measurement techniques such as sampling and remote sensing methods are explained in detail. Physical parameters used to describe aerosol properties and effect of aerosols on the radiation distribution are also discussed. The chapter also explains the objectives of the thesis and description of climatic features of the study area. |
| URI: | http://dyuthi.cusat.ac.in/purl/5096 |
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| Dyuthi- T 2162.pdf | (4.707Mb) |
| Abstract: | Laser induced plasma (LIP) emissions from some metal oxide targets were studied with corresponding metal targets of pure quality as a reference. Atomic emissions in the visible region were used in the spectroscopic procedures of LIP characterization. The studies were meant to throw light into LIP dynamics and they provided many experimental results which improved the general awareness of plasma state.When target materials were photo-ablated with an energetically suitable laser pulse, they developed electric charges in them.An electrical signal which was delivered from the target served as an alternative probe signal for the diagnostics of LIP and to track different charged states in the plasma. The signal showed a double peak distribution with positive polarity and a modified time of flight with various voltage levels of a given polarity.The expansion dynamics of LIP in magnetic field were also investigated by monitoring the voltage transients generated at the target. |
| Description: | International School of Photonics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1946 |
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| Dyuthi-T0384.pdf | (2.945Mb) |
| Abstract: | The subject of Photonics is concerned with the generation,control and utilization of photons for performing a variety of tasks.It came to existence as a consequence of the harmonious fusion of optical methods with electronic technology.Wide spread use of laser based methods in electronics is slowly replacing elecrtons with photons in the field of Communication,Control and Computing .Therefore,there is a need to promote the R & D activities in the area of Photonics and to generate well trained manpower in laser related fields.Development and characterization of photonic materials is an important subject of research in the field of Photonics.Optical and thermal characterization of photonic materials using thermal lens technique is a PhD thesis in the field of Photonics in which the author describes how thermal lens effect can be used to characterize themal and optical properties of photonic materials.Plausibility of thermal lens based logic gates is also presented in this thesis. |
| Description: | International School of Photonics, Cochin University of SCience and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2336 |
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| Dyuthi-T0610.pdf | (5.063Mb) |
| Abstract: | The photoacoustic investigations carried out on different photonic materials are presented in this thesis. Photonic materials selected for the investigation are tape cast ceramics, muItilayer dielectric coatings, organic dye doped PVA films and PMMA matrix doped with dye mixtures. The studies are performed by the measurement of photoacoustic signal generated as a result of modulated cw laser irradiation of samples. The gas-microphone scheme is employed for the detection of photoacoustic signal. The different measurements reported here reveal the adaptability and utility of the PA technique for the characterization of photonic materials.Ceramics find applications in the field of microelectronics industry. Tape cast ceramics are the building blocks of many electronic components and certain ceramic tapes are used as thermal barriers. The thermal parameters of these tapes will not be the same as that of thin films of the same materials. Parameters are influenced by the presence of foreign bodies in the matrix and the sample preparation technique. Measurements are done on ceramic tapes of Zirconia, Zirconia-Alumina combination, barium titanate, barium tin titanate, silicon carbide, lead zirconate titanateil'Z'T) and lead magnesium niobate titanate(PMNPT). Various configurations viz. heat reflection geometry and heat transmission geometry of the photoacoustic technique have been used for the evaluation of different thermal parameters of the sample. Heat reflection geometry of the PA cell has been used for the evaluation of thermal effusivity and heat transmission geometry has been made use of in the evaluation of thermal diffusivity. From the thermal diffusivity and thermal effusivity values, thermal conductivity is also calculated. The calculated values are nearly the same as the values reported for pure materials. This shows the feasibility of photoacoustic technique for the thermal characterization of ceramic tapes.Organic dyes find applications as holographic recording medium and as active media for laser operations. Knowledge of the photochemical stability of the material is essential if it has to be used tor any of these applications. Mixing one dye with another can change the properties of the resulting system. Through careful mixing of the dyes in appropriate proportions and incorporating them in polymer matrices, media of required stability can be prepared. Investigations are carried out on Rhodamine 6GRhodamine B mixture doped PMMA samples. Addition of RhB in small amounts is found to stabilize Rh6G against photodegradation and addition of Rh6G into RhB increases the photosensitivity of the latter. The PA technique has been successfully employed for the monitoring of dye mixture doped PMMA sample. The same technique has been used for the monitoring of photodegradation ofa laser dye, cresyl violet doped polyvinyl alcohol also.Another important application of photoacoustic technique is in nondestructive evaluation of layered samples. Depth profiling capability of PA technique has been used for the non-destructive testing of multilayer dielectric films, which are highly reflecting in the wavelength range selected for investigations. Eventhough calculation of thickness of the film is not possible, number of layers present in the system can be found out using PA technique. The phase plot has clear step like discontinuities, the number of which coincides with the number of layers present in the multilayer stack. This shows the sensitivity of PA signal phase to boundaries in a layered structure. This aspect of PA signal can be utilized in non-destructive depth profiling of reflecting samples and for the identification of defects in layered structures. |
| Description: | International School of Photonics, Cochin University of Science & Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2332 |
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| Dyuthi-T0606.pdf | (4.208Mb) |
| Abstract: | Image processing has been a challenging and multidisciplinary research area since decades with continuing improvements in its various branches especially Medical Imaging. The healthcare industry was very much benefited with the advances in Image Processing techniques for the efficient management of large volumes of clinical data. The popularity and growth of Image Processing field attracts researchers from many disciplines including Computer Science and Medical Science due to its applicability to the real world. In the meantime, Computer Science is becoming an important driving force for the further development of Medical Sciences. The objective of this study is to make use of the basic concepts in Medical Image Processing and develop methods and tools for clinicians’ assistance. This work is motivated from clinical applications of digital mammograms and placental sonograms, and uses real medical images for proposing a method intended to assist radiologists in the diagnostic process. The study consists of two domains of Pattern recognition, Classification and Content Based Retrieval. Mammogram images of breast cancer patients and placental images are used for this study. Cancer is a disaster to human race. The accuracy in characterizing images using simplified user friendly Computer Aided Diagnosis techniques helps radiologists in detecting cancers at an early stage. Breast cancer which accounts for the major cause of cancer death in women can be fully cured if detected at an early stage. Studies relating to placental characteristics and abnormalities are important in foetal monitoring. The diagnostic variability in sonographic examination of placenta can be overlooked by detailed placental texture analysis by focusing on placental grading. The work aims on early breast cancer detection and placental maturity analysis. This dissertation is a stepping stone in combing various application domains of healthcare and technology. |
| Description: | Department of Computer Applications Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3892 |
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| Dyuthi-T1784.pdf | (4.406Mb) |
| Abstract: | A new procedure for the classification of lower case English language characters is presented in this work . The character image is binarised and the binary image is further grouped into sixteen smaller areas ,called Cells . Each cell is assigned a name depending upon the contour present in the cell and occupancy of the image contour in the cell. A data reduction procedure called Filtering is adopted to eliminate undesirable redundant information for reducing complexity during further processing steps . The filtered data is fed into a primitive extractor where extraction of primitives is done . Syntactic methods are employed for the classification of the character . A decision tree is used for the interaction of the various components in the scheme . 1ike the primitive extraction and character recognition. A character is recognized by the primitive by primitive construction of its description . Openended inventories are used for including variants of the characters and also adding new members to the general class . Computer implementation of the proposal is discussed at the end using handwritten character samples . Results are analyzed and suggestions for future studies are made. The advantages of the proposal are discussed in detail . |
| Description: | Department of Electronics, Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2282 |
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| Dyuthi-T0583.pdf | (5.914Mb) |
| Abstract: | Cancer treatment is most effective when it is detected early and the progress in treatment will be closely related to the ability to reduce the proportion of misses in the cancer detection task. The effectiveness of algorithms for detecting cancers can be greatly increased if these algorithms work synergistically with those for characterizing normal mammograms. This research work combines computerized image analysis techniques and neural networks to separate out some fraction of the normal mammograms with extremely high reliability, based on normal tissue identification and removal. The presence of clustered microcalcifications is one of the most important and sometimes the only sign of cancer on a mammogram. 60% to 70% of non-palpable breast carcinoma demonstrates microcalcifications on mammograms [44], [45], [46].WT based techniques are applied on the remaining mammograms, those are obviously abnormal, to detect possible microcalcifications. The goal of this work is to improve the detection performance and throughput of screening-mammography, thus providing a ‘second opinion ‘ to the radiologists. The state-of- the- art DWT computation algorithms are not suitable for practical applications with memory and delay constraints, as it is not a block transfonn. Hence in this work, the development of a Block DWT (BDWT) computational structure having low processing memory requirement has also been taken up. |
| Description: | Department of Electronics, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/4543 |
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| Dyuthi-T1815.pdf | (11.18Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1307 |
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| Anandan C K 1988.PDF | (284.3Kb) |
| Abstract: | The present study aims at the preparation of an ABS (acrylonitrile-butadiene-styrene) type toughened thermoplastic by melt blending polystyrene (PS) and powdered nitrile rubber (NBR). The product is an interesting class of toughened thermoplastic, which would combine the superior mechanical and processing characteristics of PS and the excellent oil-resistant properties of NBR. In this thesis an attempt has been made to investigate systematically the effect of compatibilisation and dynamic vulcanisation on the morphology and properties of powdered nitrile rubber toughened polystyrene. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2542 |
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| Dyuthi-T0686.pdf | (8.037Mb) |
| Abstract: | Sign language is the primary means of communication for the hard to hear and speak people around the globe. Sign language emphasizes on visual possibilities as the participants are unable to hear sound patterns. Sign language uses different signs, body postures and gestures as opposed to sound patterns for communication, and evolves like any other spoken language. American Sign Language (ASL), British sign language (BSL), Arabic sign language (ArSL), Chinese sign language (CSL) and Indian sign language (ISL) are some of the widely used sign language systems around the world. There exists significant variation between sign languages, and due to these inherent variations, it is not possible to fully adopt a methodology that is found suitable for all. There are enormous complexities in ISL. Contrary to ASL, ISL sentences follow Subject-Object-Verb pattern. For example, the relative positioning of hand on face with respect to nose can convey ‘WOMAN’ or ‘THINK’ in ISL. Such complexities necessitate independent research in ISL. Sign language recognition involves integration of different categories of signs. The signs can be mainly categorized into three groups like static hand gestures, dynamic gestures and facial expression. This research focuses on these three different channels and work to identify the potential of different computational methods to address some of the associated complexities with each channel. These complexities include static gestures with resemblances, static overlaid gestures, differential movement and directional changes in dynamic gestures and facial expression changes. |
| URI: | http://dyuthi.cusat.ac.in/purl/5144 |
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| Dyuthi-T2178.pdf | (6.610Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5237 |
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| Dyuthi T-2273.pdf | (7.868Mb) |
| Abstract: | Thunderstorm is one of the most spectacular weather phenomena in the atmosphere. Many parts over the Indian region experience thunderstorms at higher frequency during pre-monsoon months (March- May), when the atmosphere is highly unstable because of high temperatures prevailing at lower levels. Most dominant feature of the weather during the pre-monsoon season over the eastern Indo-Gangetic plain and northeast India is the outburst of severe local convective storms, commonly known as ‘Nor’wester’ or ‘Kalbaishakhi’. The severe thunderstorms associated with thunder, squall line, lightning and hail cause extensive losses in agriculture, damage to structure and also loss of life. The casualty due to lightning associated with thunderstorms in this region is the highest in the world. The highest numbers of aviation hazards are reported during occurrence of these thunderstorms. In India, 72% of tornadoes are associated with this thunderstorm. |
| Description: | Department of Computer Science, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3709 |
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| Dyuthi-T1667.pdf | (7.709Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5610 |
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| Dyuthi T-2650.pdf | (33.56Mb) |
| Abstract: | Attempts have been made to attain satisfactory network structures in each of the phases of a rubber blend by minimising the cure rate imbalance by employing methods such as grafting of accelerators to the slow curing rubber, chemically bonding the crosslinking agents to the rubber in which it has lower solubility, functionalisation of the slow curing rubber, masterbatching of the curing agents to the slow curing rubber etc. Functionalisation of the slow curing constituents of NR/IIR and NR/EIPDM blends is tried using novel reagents as the first part of this study. However, the crux of the present study is a more direct approach to attaining a covulcanized state in NR/IIR and NR/EPDM blends: Precuring the slow curing rubber (IIR or EPDM) to a low level when it can still blend with NR and then to ck) the final curing after blending with NR. TNM3 precuring is also likely to minimise the viscosity mismatch. Since a low level of resmmal crosslink density is likely to be present lJ1 reclaimed rubbers, blending heat resistant reclaimed rubber such as butyl reclaim with NR may also have the same effect of precuring IIR, and then blending with NR. Hence use of IIR reclaim for developing blends with NR is also proposed to be investigated in this study |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3635 |
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| Dyuthi-T1614.pdf | (9.855Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1340 |
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| Paulson Chunkapura 1988.PDF | (907.7Kb) |
| Abstract: | There are a large number of commercial examples and property advantages of immiscible elastomer blends.73 Blends of natural rubber (NR) and polybutadiene (BR) have shown various advantages including heat stability, improved elasticity and abrasion resistance. Ethylene-propylene-diene-rubber (EPDM) blended with styrene-butadiene rubber (SBR) has shown improvements in ozone and chemical resistance with better compression set properties. Blends of EPDM and nitrile rubber (NBR) have been cited as a compromise for obtaining moderate oil and ozone resistance with improved low temperature properties. Neoprene (CR)/BR blends offer improved low temperature properties and abrasion resistance with better processing characteristics etc. However, in many of the commercial two-phase elastomer blends, segregation of the crosslinking agents, carbon black or antioxidants preferentially into one phase can result in failure to attain optimum properties. Soluble and insoluble compounding ingredients are found to be preferentially concentrated in one phase. The balance of optimum curing of both phases therefore presents a difficult problem. It has been the aim of this study to improve the performance of commercially important elastomer blends such as natural rubber (NR)/styrene-butadiene rubber (SBR) and natural rubber/polybutadiene rubber (BR) by industrially viable procedures |
| Description: | Department Of Polymer Science And Rubber technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3288 |
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| Dyuthi-T1263.pdf | (9.825Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1308 |
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| Rani Joseph 1988.PDF | (157.1Kb) |
| Abstract: | In the current study, epidemiology study is done by means of literature survey in groups identified to be at higher potential for DDIs as well as in other cases to explore patterns of DDIs and the factors affecting them. The structure of the FDA Adverse Event Reporting System (FAERS) database is studied and analyzed in detail to identify issues and challenges in data mining the drug-drug interactions. The necessary pre-processing algorithms are developed based on the analysis and the Apriori algorithm is modified to suit the process. Finally, the modules are integrated into a tool to identify DDIs. The results are compared using standard drug interaction database for validation. 31% of the associations obtained were identified to be new and the match with existing interactions was 69%. This match clearly indicates the validity of the methodology and its applicability to similar databases. Formulation of the results using the generic names expanded the relevance of the results to a global scale. The global applicability helps the health care professionals worldwide to observe caution during various stages of drug administration thus considerably enhancing pharmacovigilance |
| Description: | Department of Computer Applications, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/4098 |
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| Dyuthi-T1809.pdf | (4.817Mb) |
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