| Abstract: | The present study is the first attempt to understand population characteristics of the deep-sea pandalid shrimp, P. quasigrandis and to assess the status of these resources off Kerala coast.Total mortality coefficient (Z) of P. quasigrandis estimated by various methods.Natural mortality coefficient (M) calculated was 0.65 and 1.02 by Pauly‟sempirical formula and Srinaths‟s formula respectively The deep-sea shrimp P. quasigrandis exploited from the present fishing ground and their monetary return has started showing a declining trend. By observing the current yield and economic return, there is no further scope for increasing the catch from the present fishing ground. The study indicated that majority of the deep-sea shrimp trawlers, especially targeted for pandalid shrimps still concentrated off Kollam area (Quilon Bank). Even though researchers had located several potential deep-sea fishing grounds based on exploratory surveys in Indian EEZ , fishermen are unaware of these fishing grounds located and hence sharing the information about new potential deep-sea fishing grounds could avert the possible stock decline due to the intensive targeted deep-sea shrimp fishery in the Quilon Bank. Hence, the present study recommended that part of the effort from existing fishing grounds may be shifted to newly located deep-sea fishing grounds which will help in a sustainableexploitation of deep-sea resources off Kerala coast. |
| URI: | http://dyuthi.cusat.ac.in/purl/4995 |
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| Dyuthi-T2064.pdf | (20.62Mb) |
| Abstract: | The present thesis can be divided into three areas:1) the fabrication of a low temperature photo-luminescence and photoconductivity measuring unit 2) photo-luminescence in the chalcopyrite CulnSez and CulnS2 system for defect and composition analysis and 3) photo-luminescence and photo-conductivity of In:JS3. This thesis shows that photo-luminescence is one of most essential semiconductor characterization tool for a scientific group working on photovoltaics. Tools which can be robust, non-destructive, requiring minimal sample preparation for analysis and most informative of the device applications are sought after by industries and this thesis is towards establishing photo-luminescence as "THE" tool for semiconductor characterization. The possible application of photo-luminescence as a tool for compositional and quality analysis of semiconductor thin films has been worked upon by this thesis. Photo-conductivity complement photo-luminescence and together they provide all the information required for the fabrication of an opto-electronic device. |
| Description: | Department of Physics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2521 |
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| Dyuthi-T0680.pdf | (13.78Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5252 |
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| Dyuthi T-2288.pdf | (8.613Mb) |
| Abstract: | The main objective of the Research was to study the Delayering scheme implemented in FACT in all its aspects and to examine wlietlier implementation of delayering has contributed to improvement in organizational performance by improving managerial motivation and team effectiveness. To enable this, a post-delayering impact assessment was done by eliciting views and analyzing the perception of managers affected by the change programme. Organisation-wide Surveys were carried out as part of data collection - prior to, during and after implementation. The methodology adopted was the Case Study approach, which involved a longitudinal study of the Implementation process using tools such- as Observation, Opinion surveys and Interviews and relating the research findings with the theories/ studies on the subject for generalization and for drawing conclusions |
| Description: | School of Management Studies Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3671 |
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| Dyuthi-T1637.pdf | (4.398Mb) |
| Abstract: | Over the past decade, there is a great demand for permission to transmit large bandwidth concurrent with existing narrowband signals. In 2002, the federal communications commission (FCC) decided to permit use of ultrawideband (UWB) systems. UWB systems are unique in their large instantaneous bandwidth and potential for lowcost digital design that enables a single system to operate in different modes as a communication device, radar etc. UWB systems aim at covering the frequency band of 3.1-10.6 GHz defined by the FCC. The addition of more and more features in each new generation communication system demands universal antennas suitable for operation in multiple bands. In this regard, designing a multiband antenna which also covers the UWB range without deteriorating the UWB performance is of great interest. Also, a significant issue in communication systems is to miniaturize the antenna size while providing good performance over the operation bands. The thesis presents three different designs of CPW-fed multiband antennas. The first design uses a fractal concept to achieve multiband operation. In the second and third designs, a slotted circular monopole and a spiral monopole are used respectively for multiband operation with UWB applications. For both these cases, variations from the basic antenna geometry are also proposed in which the frequency of operation is lowered without increase in overall antenna size. Design guidelines are developed for all antennas to facilitate design on substrates of different permittivity and thickness. The antennas are analyzed in both frequency and time domain for complete characterization |
| URI: | http://dyuthi.cusat.ac.in/purl/5217 |
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| Dyuthi T-2252.pdf | (10.45Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5205 |
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| Dyuthi T-2240.pdf | (8.622Mb) |
| Abstract: | This work is aimed at building an adaptable frame-based system for processing Dravidian languages. There are about 17 languages in this family and they are spoken by the people of South India.Karaka relations are one of the most important features of Indian languages. They are the semabtuco-syntactic relations between verbs and other related constituents in a sentence. The karaka relations and surface case endings are analyzed for meaning extraction. This approach is comparable with the borad class of case based grammars.The efficiency of this approach is put into test in two applications. One is machine translation and the other is a natural language interface (NLI) for information retrieval from databases. The system mainly consists of a morphological analyzer, local word grouper, a parser for the source language and a sentence generator for the target language. This work make contributios like, it gives an elegant account of the relation between vibhakthi and karaka roles in Dravidian languages. This mapping is elegant and compact. The same basic thing also explains simple and complex sentence in these languages. This suggests that the solution is not just ad hoc but has a deeper underlying unity. This methodology could be extended to other free word order languages. Since the frame designed for meaning representation is general, they are adaptable to other languages coming in this group and to other applications. |
| URI: | http://dyuthi.cusat.ac.in/purl/978 |
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| Dyuthi-T0048.pdf | (1.404Mb) |
| Abstract: | This is a Named Entity Based Question Answering System for Malayalam Language. Although a vast amount of information is available today in digital form, no effective information access mechanism exists to provide humans with convenient information access. Information Retrieval and Question Answering systems are the two mechanisms available now for information access. Information systems typically return a long list of documents in response to a user’s query which are to be skimmed by the user to determine whether they contain an answer. But a Question Answering System allows the user to state his/her information need as a natural language question and receives most appropriate answer in a word or a sentence or a paragraph. This system is based on Named Entity Tagging and Question Classification. Document tagging extracts useful information from the documents which will be used in finding the answer to the question. Question Classification extracts useful information from the question to determine the type of the question and the way in which the question is to be answered. Various Machine Learning methods are used to tag the documents. Rule-Based Approach is used for Question Classification. Malayalam belongs to the Dravidian family of languages and is one of the four major languages of this family. It is one of the 22 Scheduled Languages of India with official language status in the state of Kerala. It is spoken by 40 million people. Malayalam is a morphologically rich agglutinative language and relatively of free word order. Also Malayalam has a productive morphology that allows the creation of complex words which are often highly ambiguous. Document tagging tools such as Parts-of-Speech Tagger, Phrase Chunker, Named Entity Tagger, and Compound Word Splitter are developed as a part of this research work. No such tools were available for Malayalam language. Finite State Transducer, High Order Conditional Random Field, Artificial Immunity System Principles, and Support Vector Machines are the techniques used for the design of these document preprocessing tools. This research work describes how the Named Entity is used to represent the documents. Single sentence questions are used to test the system. Overall Precision and Recall obtained are 88.5% and 85.9% respectively. This work can be extended in several directions. The coverage of non-factoid questions can be increased and also it can be extended to include open domain applications. Reference Resolution and Word Sense Disambiguation techniques are suggested as the future enhancements |
| Description: | Dept. Of Computer Science Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3698 |
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| Dyuthi-T1663.pdf | (4.368Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5614 |
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| Dyuthi T-2654.pdf | (1.977Mb) |
| Abstract: | The present study shows design and development of a performance evaluation prototype for IT organizations in the context of outsourcing. The main objective of this research is to help an IT organization in the context of outsourcing to realize its current standing, so it can take corrective steps where ever necessary and strive for continuous improvement. Service level management (SLM) process plays a crucial role in controlling the quality provision for IT service. Out sourcing is the process of entrusting the responsibility of providing certain goods and services to an external party. We have tried to identify as many as twenty complexities and categorized in to four headings. Complexities associated with contracts and SLAs,SLM process,SLM organization and complexities due to intrinsic characteristics. In this study it is possible to measure the quality of the performance of an IT organization in an outsourcing environment effectively |
| URI: | http://dyuthi.cusat.ac.in/purl/999 |
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| Dyuthi-T0334.pdf | (6.423Mb) |
| Abstract: | Antennas are indispensable component of any wireless communication device. An antenna is a transducer between the transmitter and the free space waves and vice versa. They efficiently transfer electromagnetic energy from a transmission line into free space. But the present day communication applications require compact and ultra wide band designs which cannot be catered by simple microstrip based designs. PIFAs have solved the problem to some extend, but the field of antennas needs more innovative designs In this thesis the design and development of compact planner antenna are presented. Emphasis is given to the design of the feed as well as the radiator resulting in simple compact uniplanar geometries. The Asymmetric coplanar feed used to excite the antennas is found to be a suitable choice for feeding compact antennas.The main objectives of the study are the design of compact single, dual and multi band antennas with uniplanar structure and extension of the design for practical GSM/WLAN applications and Ultra compact antennas using the above techniques and extension of the design to antennas for practical applications like RFID/DVB-H. All the above objectives are thoroughly studied. Antennas with ultra compact dimensions are obtained as a result of the study. Simple equations are provided to design antennas with the required characteristics. The design equations are verified by designing different antennas for different applications. |
| Description: | Department of Electronics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1927 |
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| Dyuthi-T0388.pdf | (10.97Mb) |
| Abstract: | The main objective of this thesis is to develop a compact chipless RFID tag with high data encoding capacity. The design and development of chipless RFID tag based on multiresonator and multiscatterer methods are presented first. An RFID tag using using SIR capable of 79bits is proposed. The thesis also deals with some of the properties of SIR like harmonic separation, independent control on resonant modes and the capability to change the electrical length. A chipless RFID reader working in a frequency band of 2.36GHz to 2.54GHz has been designed to show the feasibility of the RFID system. For a practical system, a new approach based on UWB Impulse Radar (UWB IR) technology is employed and the decoding methods from noisy backscattered signal are successfully demonstrated. The thesis also proposes a simple calibration procedure, which is able to decode the backscattered signal up to a distance of 80cm with 1mW output power. |
| URI: | http://dyuthi.cusat.ac.in/purl/4992 |
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| Dyuthi-T2061.pdf | (57.41Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5577 |
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| Dyuthi T-2617.pdf | (15.55Mb) |
| Abstract: | The need of miniaturization in the present day communication industry is challenging. In the present scenario, printed antenna technology is highly suitable for wireless communication due to its low profile and other desirable radiation characteristics. Small monopole type antennas are overruled by compact small antennas for present day mobile communication applications. Coplanar waveguides (CPW) are printed on one side of a dielectric substrate. CPW have attracted the attention of antenna designers due to their excellent properties like ease of integration with ‘MMIC’, low cost, wide bandwidth, flexibility towards multiband operation, low radiation leakage and less dispersion. The requirement of omnidirectional coverage, light weight and low cost made these CPW fed antennas a good candidate for wireless applications. The main focus of the thesis is the study of coplanar waveguide transmission line. Rigorous investigations were performed on both the ground plane and signal strip of a coplanar waveguide transmission line to create effective radiation characteristics. Good amount of works have been done to transform CPW line to antenna suitable for mobile phone applications |
| Description: | Department of Electronics Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3273 |
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| Dyuthi-T1247.pdf | (16.34Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5484 |
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| Dyuthi T-2526.pdf | (13.13Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5271 |
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| Dyuthi T-2307.pdf | (16.54Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5193 |
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| Dyuthi T-2228.pdf | (24.00Mb) |
| Abstract: | In recent years, there is a visible trend for products/services which demand seamless integration of cellular networks, WLANs and WPANs. This is a strong indication for the inclusion of high speed short range wireless technology in future applications. In this context UWB radio has a significant role to play as an extension/complement to existing cellular/access technology. In the present work, three major types of ultra wide band planar antennas are investigated: Monopole and Slot. Three novel compact UWB antennas, suitable for poratble applications, are designed and characterized, namely 1) Ground modified monopole 2) Serrated monopole 3) Triangular slot The performance of these designs have been studied using standard simulation tools used in industry/academia and they have been experimentally verified. Antenna design guidelines are also deduced by accounting the resonances in each structure. In addition to having compact sized, high efficiency and broad bandwidth antennas, one of the major criterion in the design of impulse-UWB systems have been the transmission of narrow band pulses with minimum distortion. The key challenge is not only to design a broad band antenna with constant and stable gain but to maintain a flat group delay or linear phase response in the frequency domain or excellent transient response in time domain. One of the major contributions of the thesis lies in the analysis of the frequency and timedomain response of the designed UWB antennas to confirm their suitability for portable pulsed-UWB systems. Techniques to avoid narrowband interference by engraving narrow slot resonators on the antenna is also proposed and their effect on a nano-second pulse have been investigated |
| Description: | Department of electronics, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3625 |
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| Dyuthi-T1605.pdf | (17.93Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5065 |
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| Dyuthi-T2131.pdf | (83.01Mb) |
| Abstract: | With the recent progress and rapid increase in the field of communication, the designs of antennas for small mobile terminals with enhanced radiation characteristics are acquiring great importance. Compactness, efficiency, high data rate capacity etc. are the major criteria for the new generation antennas. The challenging task of the microwave scientists and engineers is to design a compact printed radiating structure having broadband behavior along with good efficiency and enhanced gain. Printed antenna technology has received popularity among antenna scientists after the introduction of planar transmission lines in mid-seventies. When we view the antenna through a transmission line concept, the mechanism behind any electromagnetic radiator is quite simple and interesting. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and orientation of the discontinuities control the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non-resonant. This thesis deals with antennas that are developed from a class of transmission lines known as coplanar strip-CPS, a planar analogy of parallel pair transmission line. The specialty of CPS is its symmetric structure compared to other transmission lines, which makes the antenna structures developed from CPS quite simple for design and fabrication. The structural modifications on either metallic strip of CPS results in different antennas. The first part of the thesis discusses a single band and dual band design derived from open ended slot lines which are very much suitable for 2.4 and 5.2 GHz WLAN applications. The second section of the study is vectored into the development of enhanced gain dipoles. A single band dipole and a wide band enhanced gain dipole suitable for 5.2/5.8 GHZ band and imaging applications are developed and discussed. Last part of the thesis discusses the development of directional UWBs. Three different types of ultra-compact UWBs are developed and almost all the frequency domain and time domain analysis of the structures are discussed. |
| Description: | Department of Electronics Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3994 |
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| Dyuthi-T1803.pdf | (13.14Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5126 |
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| Dyuthi-T 2191.pdf | (2.964Mb) |
| Abstract: | Data mining is one of the hottest research areas nowadays as it has got wide variety of applications in common man’s life to make the world a better place to live. It is all about finding interesting hidden patterns in a huge history data base. As an example, from a sales data base, one can find an interesting pattern like “people who buy magazines tend to buy news papers also” using data mining. Now in the sales point of view the advantage is that one can place these things together in the shop to increase sales. In this research work, data mining is effectively applied to a domain called placement chance prediction, since taking wise career decision is so crucial for anybody for sure. In India technical manpower analysis is carried out by an organization named National Technical Manpower Information System (NTMIS), established in 1983-84 by India's Ministry of Education & Culture. The NTMIS comprises of a lead centre in the IAMR, New Delhi, and 21 nodal centres located at different parts of the country. The Kerala State Nodal Centre is located at Cochin University of Science and Technology. In Nodal Centre, they collect placement information by sending postal questionnaire to passed out students on a regular basis. From this raw data available in the nodal centre, a history data base was prepared. Each record in this data base includes entrance rank ranges, reservation, Sector, Sex, and a particular engineering. From each such combination of attributes from the history data base of student records, corresponding placement chances is computed and stored in the history data base. From this data, various popular data mining models are built and tested. These models can be used to predict the most suitable branch for a particular new student with one of the above combination of criteria. Also a detailed performance comparison of the various data mining models is done.This research work proposes to use a combination of data mining models namely a hybrid stacking ensemble for better predictions. A strategy to predict the overall absorption rate for various branches as well as the time it takes for all the students of a particular branch to get placed etc are also proposed. Finally, this research work puts forward a new data mining algorithm namely C 4.5 * stat for numeric data sets which has been proved to have competent accuracy over standard benchmarking data sets called UCI data sets. It also proposes an optimization strategy called parameter tuning to improve the standard C 4.5 algorithm. As a summary this research work passes through all four dimensions for a typical data mining research work, namely application to a domain, development of classifier models, optimization and ensemble methods. |
| Description: | Department of Computer Science, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3127 |
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| Dyuthi-T1101.pdf | (2.945Mb) |
| Description: | International School of Photonics |
| URI: | http://dyuthi.cusat.ac.in/purl/5026 |
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| Dyuthi-2092.pdf | (10.46Mb) |
| Abstract: | In recent years,photonics has emerged as an essential technology related to such diverse fields like laser technology,fiber optics,communication,optical signal processing,computing,entertainment,consumer electronics etc.Availabilities of semiconductor lasers and low loss fibers have also revolutionized the field of sensor technology including telemetry. There exist fiber optic sensors which are sensitive,reliable.light weight and accurate devices which find applications in wide range of areas like biomedicine,aviation,surgery,pollution monitoring etc.,apart from areas in basic sciences.The present thesis deals with the design,fabrication and characterization of a variety of cost effective and sensitive fiber optic sensors for the trace detetction of certain environment pollutants in air and water.The sensor design is carried out using the techniques like evanescent waves,micro bending and long period gratings. |
| Description: | International School of Photonics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2331 |
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| Dyuthi-T0605.pdf | (6.325Mb) |
| Abstract: | Hevea latex is a natural biological liquid of very complex composition .Besides rubber hydrocarbons,it contains many proteinous and resinous substances,carbohydrates,inorganic matter,water,and others.The Dry Rubber Content (DRC) of latex varies according to season, tapping system,weather,soil conditions ,clone,age of the tree etc. The true DRC of the latex must be determined to ensure fair prices for the latex during commercial exchange.The DRC of Hevea latex is a very familiar term to all in the rubber industry.It has been the basis for incentive payments to tappers who bring in more than the daily agreed poundage of latex.It is an important parameter for rubber and latex processing industries for automation and verious decesion making processes.This thesis embodies the efforts made by me to determine the DRC of rubber latex following different analytical tools such as MIR absorption,thermal analysis.dielectric spectroscopy and NIR reflectance.The rubber industry is still Looking for a compact instrument that is accurate economical,easy to use and environment friendly.I hope the results presented in this thesis will help to realise this goal in the near future. |
| Description: | Department of Instrumentation, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2683 |
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| Dyuthi-T0735.pdf | (4.333Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5579 |
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| Dyuthi T-2619.pdf | (11.13Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5332 |
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| Dyuthi T-2368-a.pdf | (772.1Kb) |
| Dyuthi T-2368-b.pdf | (553.2Kb) |
| Dyuthi T-2368-c.pdf | (7.126Mb) |
| Abstract: | Filters are one of the essential components in the RF and wireless communication systems. Small sized planar lowpass filters with good electrical characteristics along with low cost, light weight and ease of fabrication are highly desirable for the front end of modern communication systems to suppress harmonics and spurious signals. Design of compact lowpass filters with improved performance and diverse specifications for numerous applications is a huge challenge. In this thesis, high performance planar compact lowpass filters using multiple patch resonators on high impedance transmission line are developed. Design techniques of different types of patch resonators and their modifications to enhance the performance of the filters are presented.Patch resonators are designed by using high impedance short circuited stubs and low impedance open circuited patches. In the first stage of filter realization, compact lowpass filter having sharp roll-off using triangular and funnel patch resonators is presented. The structure is modified further to enhance the relative stopband bandwidth of the filter. In the third stage, another resonator has been introduced near the feed line to achieve sharp roll-off for the same cutoff frequency, stopband bandwidth and suppression level. To obtain compactness, high suppression level and wide stopband in filter design, low thickness substrate is tested and proved in the fourth stage. Realizations of planar compact lowpass filter with very sharp roll-off near the cutoff frequency have been presented using stepped impedance polygonal patch resonators. By increasing the patch size and number of resonators, the stopband bandwidth and suppression level have to be enhanced to a great extent. Enhancement of performance characteristics of lowpass filter design is continually being extended. By using high value capacitance patch, the stopband suppression level of the filter with sharp roll-off rate is achieved. Elliptic function lowpass filter with ultra-sharp roll-off is also developed using elliptic shaped patch resonators. Throughout the study, low cost substrate having permittivity 4.4 is used for the filter design. All the designed filters have been fabricated and predicted results are validated by the measurements. |
| URI: | http://dyuthi.cusat.ac.in/purl/5170 |
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| Dyuthi-T2204.pdf | (7.436Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5569 |
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| Dyuthi T-2611.pdf | (9.897Mb) |
| Abstract: | Antennas are necessary and vital components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Reconfigurable antennas can adjust with changing system requirements or environmental conditions and provide additional levels of functionality that may result in wider instantaneous frequency bandwidths, more extensive scan volumes, and radiation patterns with more desirable side lobe distributions. Their agility and diversity created new horizons for different types of applications especially in cognitive radio, Multiple Input Multiple Output Systems, satellites and many other applications. Reconfigurable antennas satisfy the requirements for increased functionality, such as direction finding, beam steering, radar, control and command, within a confined volume. The intelligence associated with the reconfigurable antennas revolved around switching mechanisms utilized. In the present work, we have investigated frequency reconfigurable polarization diversity antennas using two methods: 1. By using low-loss, high-isolation switches such as PIN diode, the antenna can be structurally reconfigured to maintain the elements near their resonant dimensions for different frequency bands and/or polarization. 2. Secondly, the incorporation of variable capacitors or varactors, to overcome many problems faced in using switches and their biasing. The performances of these designs have been studied using standard simulation tools used in industry/academia and they have been experimentally verified. Antenna design guidelines are also deduced by accounting the resonances. One of the major contributions of the thesis lies in the analysis of the designed antennas using FDTD based numerical computation to validate their performance. |
| Description: | Department of Electronics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3085 |
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| Dyuthi-T1059.pdf | (27.41Mb) |
| Abstract: | The main objective of this thesis is to design and develop spectral signature based chipless RFID tags Multiresonators are essential component of spectral signature based chipless tags. To enhance the data coding capacity in spectral signature based tags require large number of resonances in a limited bandwidth. The frequency of the resonators have to be close to each other. To achieve this condition, the quality factor of each resonance needs to be high. The thesis discusses about various types of multiresonators, their practical implementation and how they can be used in design. Encoding of data into spectral domain is another challenge in chipless tag design. Here, the technique used is the presence or absence encoding technique. The presence of a resonance is used to encode Logic 1 and absence of a speci c resonance is used to encode Logic 0. Di erent types of multiresonators such as open stub multiresonators, coupled bunch hairpin resonators and shorted slot ground ring resonator are proposed in this thesis. |
| URI: | http://dyuthi.cusat.ac.in/purl/5046 |
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| Dyuthi-T2118.pdf | (22.64Mb) |
| Dyuthi-T2118.pdf | (22.64Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5521 |
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| Dyuthi T-2563.pdf | (7.817Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1697 |
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| Dyuthi-T0055.pdf | (3.662Mb) |
| Abstract: | In this work we present the results of our attempt to build a compact photothermal spectrometer capable of both manual and automated mode of operation.The salient features of the system include the ability to analyse thin film, powder and polymer samples. The tool has been in use to investigate thermal, optical and transport properties. Binary and ternary semiconducting thin films were analysed for their thermal diffusivities. The system could perform thickness measurements nondestructively. Ion implanted semiconductors are widely studied for the effect of radiation induced defects. We could perform nondestructive imaging of defects using our spectrometer.The results reported in his thesis on the above in addition to studies on In2S3 and transparent conducting oxide ZnO have been achieved with this spectrometer. Various polymer samples have been easily analysed for their thermal diffusivities. The technique provided ease of analysis not achieved with conventional techniques like TGA and DSC. Industrial application of the tool has also been proved by analyzing defects of welded joints and adhesion of paints. Indigenization of the expensive lock-in-amplifier and automation has been the significant achievement in the course of this dissertation. We are on our way to prove the noise rejection capabilities of our PC LIA. |
| Description: | Department of Physics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2372 |
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| Dyuthi-T0644.pdf | (8.698Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5568 |
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| Dyuthi T-2610.pdf | (6.362Mb) |
| Abstract: | Electrocardiogram gives the information regarding the health of the patients by monitoring the bioelectric potentials generated by the sinoatrial node in the heart. These signals can be collected by using electrodes suitably placed on the body of a patient. The normal human ECG lie in the frequency range of 0.05-100 Hz and the most useful information is contained in the range of 0.5-45 Hz. Even though a large amount of work has already been done in the field of ECG classification, no classification system has made an attempt in identifying the isolated abnormalities which pose a silent threat to patients. An adaptive filtering technique for denoising the ECG which is based on Genetic Algorithm (GA) tuned Sign-Data Least Mean Square (SD-LMS) algorithm is proposed. This algorithm gave an average signal to noise ratio improvement of 10.75 dB for baseline wander and 24.26 dB for power line interference. It is seen that the step size ‘μ’ optimized with GA helps in obtaining better SNR value without causing any damage to the information content in the ECG. A new wavelet for automatic classification of arrhythmias from electrocardiogram is proposed. This new wavelet is formed as a sum of shifted Gaussians so that it resembles a normal ECG. This shape has been chosen with the aim of extracting maximum information from the ECG under analysis. The classification performance was studied using the most commonly used database, the MIT-BIH Arrhythmia database. The shifted and summed Gaussian wavelet was then optimized using GA. The optimum wavelet for classification was obtained after several runs of the GA algorithm. The ECG class labeling was done according to the Association for the Advancement of Medical Instrumentation (AAMI). The wavelet scales corresponding to the different frequency levels giving maximum classification performance were identified by selecting finer scales. Probabilistic Neural Network classifier was used for classification purpose. The proposed classification system offered better results than that reported in literature by giving an overall sensitivity of 97.01% for Normal beats, 75.20% for Supraventricular beats and 93.06% for Ventricular beats. As mentioned above this technique could exclusively identify some of the isolated abnormalities present in the patient records. |
| URI: | http://dyuthi.cusat.ac.in/purl/5143 |
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| Dyuthi-T2177.pdf | (4.847Mb) |
| Abstract: | The focus of self-assembly as a strategy for the synthesis has been confined largely to molecules, because of the importance of manipulating the structure of matter at the molecular scale. We have investigated the influence of temperature and pH, in addition to the concentration of the capping agent used for the formation of the nano-bio conjugates. For example, the formation of the narrower size distribution of the nanoparticles was observed with the increase in the concentration of the protein, which supports the fact that γ-globulin acts both as a controller of nucleation as well as stabiliser. As analyzed through various photophysical, biophysical and microscopic techniques such as TEM, AFM, C-AFM, SEM, DLS, OPM, CD and FTIR, we observed that the initial photoactivation of γ-globulin at pH 12 for 3 h resulted in small protein fibres of ca. Further irradiation for 24 h, led to the formation of selfassembled long fibres of the protein of ca. 5-6 nm and observation of surface plasmon resonance band at around 520 nm with the concomitant quenching of luminescence intensity at 680 nm. The observation of light triggered self-assembly of the protein and its effect on controlling the fate of the anchored nanoparticles can be compared with the naturally occurring process such as photomorphogenesis.Furthermore,our approach offers a way to understand the role played by the self-assembly of the protein in ordering and knock out of the metal nanoparticles and also in the design of nano-biohybrid materials for medicinal and optoelectronic applications. Investigation of the potential applications of NIR absorbing and water soluble squaraine dyes 1-3 for protein labeling and anti-amyloid agents forms the subject matter of the third chapter of the thesis. The study of their interactions with various proteins revealed that 1-3 showed unique interactions towards serum albumins as well as lysozyme. 69%, 71% and 49% in the absorption spectra as well as significant quenching in the fluorescence intensity of the dyes 1-3, respectively. Half-reciprocal analysis of the absorption data and isothermal titration calorimetric (ITC) analysis of the titration experiments gave a 1:1 stoichiometry for the complexes formed between the lysozyme and squaraine dyes with association constants (Kass) in the range 104-105 M-1. We have determined the changes in the free energy (ΔG) for the complex formation and the values are found to be -30.78, -32.31 and -28.58 kJmol-1, respectively for the dyes 1, 2 and 3. Furthermore, we have observed a strong induced CD (ICD) signal corresponding to the squaraine chromophore in the case of the halogenated squaraine dyes 2 and 3 at 636 and 637 nm confirming the complex formation in these cases. To understand the nature of interaction of the squaraine dyes 1-3 with lysozyme, we have investigated the interaction of dyes 1-3 with different amino acids. These results indicated that the dyes 1-3 showed significant interactions with cysteine and glutamic acid which are present in the side chains of lysozyme. In addition the temperature dependent studies have revealed that the interaction of the dye and the lysozyme are irreversible. Furthermore, we have investigated the interactions of these NIR dyes 1-3 with β- amyloid fibres derived from lysozyme to evaluate their potential as inhibitors of this biologically important protein aggregation. These β-amyloid fibrils were insoluble protein aggregates that have been associated with a range of neurodegenerative diseases, including Huntington, Alzheimer’s, Parkinson’s, and Creutzfeldt-Jakob diseases. We have synthesized amyloid fibres from lysozyme through its incubation in acidic solution below pH 4 and by allowing to form amyloid fibres at elevated temperature. To quantify the binding affinities of the squaraine dyes 1-3 with β-amyloids, we have carried out the isothermal titration calorimetric (ITC) measurements. The association constants were determined and are found to be 1.2 × 105, 3.6× 105 and 3.2 × 105 M-1 for the dyes, 1-3, respectively. To gain more insights into the amyloid inhibiting nature of the squaraine dyes under investigations, we have carried out thioflavin assay, CD, isothermal titration calorimetry and microscopic analysis. The addition of the dyes 1-3 (5μM) led to the complete quenching in the apparent thioflavin fluorescence, thereby indicating the destabilization of β-amyloid fibres in the presence of the squaraine dyes. Further, the inhibition of the amyloid fibres by the squaraine dyes 1-3, has been evidenced though the DLS, TEM AFM and SAED, wherein we observed the complete destabilization of the amyloid fibre and transformation of the fibre into spherical particles of ca. These results demonstrate the fact that the squaraine dyes 1-3 can act as protein labeling agents as well as the inhibitors of the protein amyloidogenesis. The last chapter of the thesis describes the synthesis and investigation of selfassembly as well as bio-imaging aspects of a few novel tetraphenylethene conjugates 4-6.Expectedly, these conjugates showed significant solvatochromism and exhibited a hypsochromic shift (negative solvatochromism) as the solvent polarity increased, and these observations were justified though theoretical studies employing the B3LYP/6-31g method. We have investigated the self-assembly properties of these D-A conjugates though variation in the percentage of water in acetonitrile solution due to the formation of nanoaggregates. Further the contour map of the observed fluorescence intensity as a function of the fluorescence excitation and emission wavelength confirmed the formation of J-type aggregates in these cases. To have a better understanding of the type of self-assemblies formed from the TPE conjugates 4-6, we have carried out the morphological analysis through various microscopic techniques such as DLS, SEM and TEM. 70%, we observed rod shape architectures having ~ 780 nm in diameter and ~ 12 μM in length as evidenced through TEM and SEM analysis. We have made similar observations with the dodecyl conjugate 5 at ca. 70% and 50% water/acetonitrile mixtures, the aggregates formed from 4 and 5 were found to be highly crystalline and such structures were transformed to amorphous nature as the water fraction was increased to 99%. To evaluate the potential of the conjugate as bio-imaging agents, we have carried out their in vitro cytotoxicity and cellular uptake studies though MTT assay, flow cytometric and confocal laser scanning microscopic techniques. Thus nanoparticle of these conjugates which exhibited efficient emission, large stoke shift, good stability, biocompatibility and excellent cellular imaging properties can have potential applications for tracking cells as well as in cell-based therapies. In summary we have synthesized novel functional organic chromophores and have studied systematic investigation of self-assembly of these synthetic and biological building blocks under a variety of conditions. The investigation of interaction of water soluble NIR squaraine dyes with lysozyme indicates that these dyes can act as the protein labeling agents and the efficiency of inhibition of β-amyloid indicate, thereby their potential as anti-amyloid agents. |
| URI: | http://dyuthi.cusat.ac.in/purl/4949 |
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| Dyuthi-T2025.pdf | (9.970Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5291 |
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| Dyuthi T-2327.pdf | (10.67Mb) |
| Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2998 |
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| Dyuthi-T0978.pdf | (19.43Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5412 |
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| Dyuthi T-2453.pdf | (10.96Mb) |
| Abstract: | The main focus of the present study was to develop ideal low band gap D-A copolymers for photoconducting and non-linear optical applications. This chapter summarizes the overall research work done. Designed copolymers were synthesized via direct arylation or Suzuki coupling reactions. Copolymers were characterized by theoretical and experimental methods. The suitability of these copolymers in photoconducting and optical limiting devices has been investigated.The results suggest that the copolymers investigated in the present study have a good non-linear optical response and are comparable to or even better than the D-A copolymers reported in the literature and hence could be chosen as ideal candidates with potential applications for non-linear optics. The results also show that the structures of the polymers have great impact on NLO properties. Copolymers studied here exhibits good optical limiting property at 532 nm wavelength due to two-photon absorption (TPA) process. The results revealed that the two copolymers, (P(EDOT-BTSe) and P(PH-TZ)) exhibited strong two-photon absorption and superior optical power limiting properties, which are much better than that of others. |
| URI: | http://dyuthi.cusat.ac.in/purl/5007 |
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| Dyuthi-T2074.pdf | (6.531Mb) |
| Abstract: | Most of the commercial and financial data are stored in decimal fonn. Recently, support for decimal arithmetic has received increased attention due to the growing importance in financial analysis, banking, tax calculation, currency conversion, insurance, telephone billing and accounting. Performing decimal arithmetic with systems that do not support decimal computations may give a result with representation error, conversion error, and/or rounding error. In this world of precision, such errors are no more tolerable. The errors can be eliminated and better accuracy can be achieved if decimal computations are done using Decimal Floating Point (DFP) units. But the floating-point arithmetic units in today's general-purpose microprocessors are based on the binary number system, and the decimal computations are done using binary arithmetic. Only few common decimal numbers can be exactly represented in Binary Floating Point (BF P). ln many; cases, the law requires that results generated from financial calculations performed on a computer should exactly match with manual calculations. Currently many applications involving fractional decimal data perform decimal computations either in software or with a combination of software and hardware. The performance can be dramatically improved by complete hardware DFP units and this leads to the design of processors that include DF P hardware.VLSI implementations using same modular building blocks can decrease system design and manufacturing cost. A multiplexer realization is a natural choice from the viewpoint of cost and speed.This thesis focuses on the design and synthesis of efficient decimal MAC (Multiply ACeumulate) architecture for high speed decimal processors based on IEEE Standard for Floating-point Arithmetic (IEEE 754-2008). The research goal is to design and synthesize deeimal'MAC architectures to achieve higher performance.Efficient design methods and architectures are developed for a high performance DFP MAC unit as part of this research. |
| Description: | Department of Computer Science, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3105 |
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| Dyuthi-T1079.pdf | (7.708Mb) |
| Abstract: | Systems which employ underwater acoustic energy for observation or communication are called sonar systems. The active and passive sonars are the two types of systems used for the detection and localisation of targets in underwater. Active sonar involves the transmission of an acoustic signal which, when reflected from a target, provides the sonar receiver with a basis for the detection and estimation. Passive sonar bases its detection and estimation on sounds which emanate from the target itself--Machinery noise, flow noise, transmission from its own active sonar etc.Electroacoustic transducers are used in sonar systems for the transmission and detection of acoustic energy. The transducer which is used for the transmission of acoustic energy is called projector and the one used for reception is called hydrophone. Since a single transducer is not sufficient enough for long range and directional transmission, a properly distributed array of transducers are to be used [9-11].The need and requirement for spatial processing to generate the most favourable directivity patterns for transducer systems used in underwater applications have already been analysed by several investigators [12-21].The desired directivity pattern can be either generated by the use of suitable focussing techniques or by an array of non-directional sensor elements, whose arrangements, spacing and the mode of excitation provide the required radiation pattern or by the combination of these.While computing that the directivity pattern, it is assumed strength of the elements are unaffected by the the source acoustic pressure at each source. However, in closely packed a r r a y s , the acoustic interaction effects experienced among the elements will modify the behaviour of individual elements and in turn will reduce the acoust ic source leve 1 wi t h respect to the maximum t heoret i cal va 1ue a s well as degrade the beam pa t tern. Th i s ef fect shou 1d be reduced in systems that are intended to generate high acoustic power output and unperturbed beam patterns [2,22-31].The work herein presented includes an approach for designing efficient and well behaved underwater transd~cer arrays, taking into account the acoustic interaction effect experienced among the closely packed multielement arrays.Architectural modifications reducing the interaction effect different radiating apertures. |
| Description: | Department of Electronics, Cochin University of Science and Technology. |
| URI: | http://dyuthi.cusat.ac.in/purl/2298 |
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| Dyuthi-T0590.pdf | (2.974Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5225 |
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| Dyuthi T-2260.pdf | (65.15Mb) |
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