| Abstract: | Nonlinear dynamics has emerged into a prominent area of research in the past few Decades.Turbulence, Pattern formation,Multistability etc are some of the important areas of research in nonlinear dynamics apart from the study of chaos.Chaos refers to the complex evolution of a deterministic system, which is highly sensitive to initial conditions. The study of chaos theory started in the modern sense with the investigations of Edward Lorentz in mid 60's. Later developments in this subject provided systematic development of chaos theory as a science of deterministic but complex and unpredictable dynamical systems. This thesis deals with the effect of random fluctuations with its associated characteristic timescales on chaos and synchronization. Here we introduce the concept of noise, and two familiar types of noise are discussed. The classifications and representation of white and colored noise are introduced. Based on this we introduce the concept of randomness that we deal with as a variant of the familiar concept of noise. The dynamical systems introduced are the Rossler system, directly modulated semiconductor lasers and the Harmonic oscillator. The directly modulated semiconductor laser being not a much familiar dynamical system, we have included a detailed introduction to its relevance in Chaotic encryption based cryptography in communication. We show that the effect of a fluctuating parameter mismatch on synchronization is to destroy the synchronization. Further we show that the relation between synchronization error and timescales can be found empirically but there are also cases where this is not possible. Studies show that under the variation of the parameters, the system becomes chaotic, which appears to be the period doubling route to chaos. |
| Description: | International School of Photonics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1925 |
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| Dyuthi-T0472.pdf | (4.136Mb) |
| Abstract: | It has been shown recently that systems driven with random pulses show the signature of chaos ,even without non linear dynamics.This shows that the relation between randomness and chaos is much closer than it was understood earlier .The effect of random perturbations on synchronization can be also different. In some cases identical random perturbations acting on two different chaotic systems induce synchronizations. However most commonly ,the effect of random fluctuations on the synchronizations of chaotic system is to destroy synchronization. This thesis deals with the effect of random fluctuations with its associated characteristic timescales on chaos and synchronization. The author tries to unearth yet another manifestation of randomness on chaos and sychroniztion. This thesis is organized into six chapters. |
| Description: | International School of Photonics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3391 |
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| Dyuthi-T1368.pdf | (2.226Mb) |
| Abstract: | The thesis embodies the results of a study on the variations in the parameters of productivity of two test species, a chlorophycean alga and a diatom. The chlorophycean alga Scenedesmus abundans was isolated from a fresh water pond whereas the diatom Nitzschia clausii was from the Cochin backwaters. Their growth parameters and their variations due to the effect of addition of some heavy metals have been studied. The growth parameters include biomass, production, respiration, photosynthetic pigments and end products of photosynthesis. The cell numbers were estimated by using a haemocytometer and production and respiration by oxygen light and dark technique. Spectrophotometric analysis for pigments, anthrone method for carbohydrate and heated biuret method for protein were the different methods employed in the present investigation. The present study is confined to nickel, cobalt, trivalent and hexavalent chromium. Different metals are discharged from various industries in and around Cochin. The effects of these metals individually and in combination are studied. Experiments to determine the effects of interaction of metals in combination enabled the assessment of the antagonistic and synergistic effect of metals on test species. The concentration or accumulation of metals on algae was determined by Atomic Absorption Spectrophotometry. The thesis has been divided into seven chapters. The introductory chapter explains the relevance of the present investigation. Chapter two presents the review of literature based on the work in relation to toxicity. Third chapter gives a detailed description of the material and specialized methods followed for the study. The effects of various metals selected for study - nickel, cobalt, trivalent and hexavalent chromium on the qualitative and quantitative aspects of productivity forms the subject of matter of the fourth chapter. The fifth chapter gives the impact of metals in combination on two species of algae. A general discussion and summary are included in the sixth and seventh chapters |
| Description: | School of Environmental Studies, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3187 |
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| Dyuthi-T1161.pdf | (4.503Mb) |
| Abstract: | The present study has helped in finding out an efficient growth promoting substance for the fry of Liza garsia. 1Zfimethyltestosterone at the dosages of 2 mg/kg diet is the most effective anabolic agent for Liza parsia. The study also shows that by incorporating 8 mg MT/kg of diet the protein level in the diet could be reduced from 35 to 30%. thereby a significant saving in the cost of feed could be obtained. Further, the anabolic effect of MT helps to reduce the rearing period during the production of fingerlings from the fry stage. |
| Description: | Central Marine Fisheries Research Institute |
| URI: | http://dyuthi.cusat.ac.in/purl/3373 |
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| Dyuthi-T1350.pdf | (7.474Mb) |
| Abstract: | The thesis is Studies on the Effect or the Obganophosphorus Pesticide Ekalux(R) EC 25 on the Bacterial Flora or Villorita Cyprinoides Var.Cochinensis (Hanley). For the present investigation, the black clam Villorita gyprinoides var. cochinensis (Hanley), a most common clam genus present in this estuarine system has been selected as test organaism and Ekalux (R) EC 25 as toxicant. The aspects dealt with are 1. Total heterotrophic bacterial population, 2. Generic composition, 3. Hydrolytic enzyme producing bacteria, 4. Antibiotic resistance, 5. Heavy metal resistance, 6. The effect of pesticide concentration on the growth of the bacteria and 7. Effect of temperature, pH and sodium chloride on the growth and phosphate release of selected isolates.The samples for the experiment were collected from the Vembanad Lake, near Kumbalam Island during the period of September 1985 to May '86. The THB of the estuarine water and clams contained 6.5 x I04/ml and 2.975 x l06/g respectively, immediately after collection. Untreated water and clam samples showed enormous increase in THB from 0 hr population. The treated samples (water and clams) contained higher THB than 0 hr. In general, THB was observed to increase tremendously in the samples treated with pesticide when compared to their native flora. With reference to various concentrations of pesticides, THB recorded an increase with increase of concentration in water and clam samples. |
| Description: | School of Marine Sciences, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3248 |
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| Dyuthi-T1222.pdf | (3.792Mb) |
| Abstract: | This thesis Entitled studies on the effect of toxic heavy metal mercury on the physiology and biochemistry of an estuarine crab scylla serrata (Forskal). Evaluate the toxicity of three sub lethal concentrations of mercury, viz., 0.009 mg/l, 0.02 mg/1, and 0.04 mg/l on the mud crab, Scylla serrata through bioaccumulation, and depuration studies. To characterize the biochemical responses to the sub-lethal stress of mercury in chelate muscles, abdominal muscles, hepatopancreas and gills. To study the activity pattern of acid and alkaline phosphatases in mercury-exposed crabs. To evaluate the induced changes in these tissues through histopathological studies,The Cochin backwaters is one of the most productive and biologically active backwater systems, and is the habitat of varieties of fishes, mollusks, and crustaceans, though this water body also receives tons of effluents from factories located on the banks of the river, Periyar.To study the activity levels of acid and alkaline phosphatases in crabs, at three time periods, exposed to three sub lethal concentration of mercury, |
| Description: | School of Environmental Studies, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3115 |
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| Dyuthi-T1089.pdf | (9.625Mb) |
| Abstract: | Bottom trawling is one among the most destructive human induced physical disturbances inflicted to seabed and its living communities. The bottom trawls are designed to tow along the sea floor, which on its operation indiscriminately smashes everything on their way crushing, killing, burying and exposing to predators the benthic fauna. Bottom trawling causes physical and biological damages that are irreversible, extensive and long lasting. The commercial trawling fleet of India consists of 29,241 small and medium-fishing boats. The northwest coast of India has the largest fishing fleet consisting of 23,618 mechanized vessels, especially the bottom trawlers. However, attempts were not made to study the impact of bottom trawling along Northwest coast of India. The estimated optimum fleet size of Gujarat is 1,473 mechanised trawlers while 7402 commercial trawlers are operated from the coast of Gujarat. Veraval port was designed initially for 1,200 fishing trawlers but 2793 trawlers are being operated from this port making it the largest trawler port of Gujarat. The aim of this study was to investigate the effects of bottom trawling on the substratum and the associated benthic communities of commercial trawling grounds of Veraval coast. The study compared the differences between the samples collected before and after experimental trawling to detect the impacts of bottom trawling. Attempts were made to assess the possible impact of bottom trawling on:(i) the sediment characteristics (ii)the sediment heavy metals (iii) epifauna (iv) macrobenthos and (v) meiobenthos. This study is expected to generate information on trawling impacts of the studied area that will help in better management of the biological diversity and integrity of the benthic fauna off Veraval coast. An exhaustive review on the studies conducted around the world and in India on impact of bottom trawling on the benthic fauna is also detailed.In the present study, the bottom trawling induced variations on sediment organic matter, epifauna, macrobenthos and meiobenthos were evident. It was also observed that the seasonal/ natural variations were more prominent masking the trawling effect on sediment texture and heavy metals. Enforcement of control of excess bottom trawlers and popularization of semi pelagic trawls designed to operate a little distance above the sea bottom for off bottom resources will minimize disturbance on the sea bottom. Training and creating awareness in responsible fishing should be made mandatory requirements, to the coastal communities. They should be made wardens to protect the valuable resources for the benefit of sustainability. To protect the biodiversity and ecosystem health, the imminent need is to survey and make catalogue, identification of sensitive areas or hot spots and to adopt management strategies for the conservation and biodiversity protection of benthic fauna. The present study is a pioneering work carried out along Veraval coast. This thesis will provide a major fillip to the studies on impact of bottom trawling on the benthic fauna along the coast of India. |
| URI: | http://dyuthi.cusat.ac.in/purl/2883 |
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| Dyuthi-T0880.pdf | (10.76Mb) |
| Abstract: | This thesis is an attempt by the author to assess the suitability of Metapenaeus dobsoni (Miers), an economically important crustacean species as a sentinel organism of trace metal pollution. The results of detailed investigations on seasonal variation, bioassay, accumulation and depuration of three metals viz., mercury, copper and zinc are presented and discussed. The importance of trace metals in the aquatic environment and their present status in the study area - Cochin backwaters, the significance of crustacean fisheries, the species M. dobsoni and the objectives of the present studies are described in Chapter 1. The methodology adopted during the investigation is given in Chapter 2. Chapter 3 delineates the seasonal variation of Hg, Cu and Zn in the edible and non-edible parts of M. dobsoni collected from Cochin backwaters for a period of one year (June 1984-May 1985). The results of bioassay experiments are given in Chapter 4. Kinetics of accumulation ,retention and depuration of trace metals, their biological half-life, the influence of size group and environmental factors are given in Chapter 5. The effect of these metals on the physiological response of M. dobsoni viz. oxygen consumption is included in Chapter 6. A summary and list of references are also appended. |
| Description: | School of Marine Sciences, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3627 |
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| Dyuthi-T1607.pdf | (3.314Mb) |
| Abstract: | Solid electrolytes for applications like chemical sensing, energy storage, and conversion have been actively investigated and developed since the early sixties. Although of immense potential, solid state protonic conductors have been ignored in comparison with the great interest that has been shown to other ionic conductors like lithium and silver ion conductors. The non-availability of good, stable protonic conductors could be partly the reason for this situation. Although organic solids are better known for their electrical insulating character, ionic conductors of organic origin constitute a recent addition to the class of ionic conductors. However, detailed studies (N1 such conductors are scarce. Also the last decade has witnessed an unprecedented boom in research on organic "conducting polymers". These newly devised materials show conductivity spanning from insulator to metallic regimes, which can be manipulated by appropriate chemical treatment. They find applications in devices ranging from rechargeable batteries to "smart windows". This thesis mainly deals with the synthesis and investigations on the electrical properties of (i) certain organbc protonic conductors derived from ethylenediamine and (ii) substituted polyanilines |
| Description: | Department of Physics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3678 |
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| Dyuthi-T1644.pdf | (2.773Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1143 |
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| Thomas P Thomas 1982.PDF | (718.2Kb) |
| Abstract: | ac-qlncnn phosphorylsse is en ilportent enzyme in glycoiysis. It is the first used knows to exhibit ellosteric properties and lance its inhibition end ectivetion have significant effect on the rete ot qlycolysis. The thesis deals with 11 detailed study of the structure. inhibition and control or this snlrlls from rabbit uncle and troll e merino eninelo ‘the thesis is divided into two parts. Port 1 deals with studies on rabbit uncle glycogen phospherylese. After e review of the relevant literetnre (Chapter 1) the inhibition and chancel sodiiicetion studies on rabbit ensyle ere discussed in chepters 2 to 5. Chapter 6. gives the methods used for the study |
| Description: | School of Marine Sciences, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3652 |
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| Dyuthi-T1626.pdf | (10.43Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1172 |
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| Muraleedharan P M 1985.PDF | (343.4Kb) |
| Abstract: | In India, directed research on penaeid prawn nutrition was taken up only recently when the aquaculture of prawns gained momentum. One of the important penaeid prawns sought for culture and has great potential is Penagus indiggs, H.Milne Edwards. The Central Marine Fisheries Research Institute working on different aspects of culture of this species over the past one and half decades, has developed a hatchery technology for mass production of its seed and has suggested several improvements on its farming in the grow-out systems. One of the areas of active research in this direction has been on the nutrition of the species with a view to develop suitable feed not only for hatchery production of seed, but also in the field culture. As part of this investigation, the present study, on the evaluation of different protein and carbohydrate sources and mineral requirements for the juvenile E, indicus was taken up and the results obtained are embodied in the thesis |
| Description: | Central Marine Fisheries Research Institute |
| URI: | http://dyuthi.cusat.ac.in/purl/3646 |
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| Dyuthi-T1622.pdf | (7.347Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1229 |
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| Syed Ahmad Ali 1989.PDF | (586.0Kb) |
| Description: | School of Industrial Fisheries, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2873 |
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| Dyuthi-T0870.pdf | (16.45Mb) |
| Abstract: | ’l‘he reproductive physiology of the female palaemonid prawn M. idella has been investigated by adopting a comprehensive approach to the problem. The major aspects of the study included investigations on breeding biology and process of oogenesis, variations in the biochemical components in relation to maturation, neuroendocrine relations and control over reproduction, and artificial insemination. The prawns used in the present study were procured from Vembanad Lake at Panavally village - a place nearly 20 km. away from Cochin. The studies were carried out using standard histological and biochemical methods. The modern technique of electroejaculation was adopted for extrusion of spermatophores in artificial insemination experiment. |
| Description: | Centre of Advanced Studies in Mariculture, Central Marine Fisheries Research Institute (CMFRI) |
| URI: | http://dyuthi.cusat.ac.in/purl/3647 |
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| Dyuthi-T1633.pdf | (4.813Mb) |
| Abstract: | Kerala has been one of the leading maritime states in India for the exploitation and export of mud crabs (Raj, 1992). Many brackishwater systems like the Ashtamudi lake, Vembanad lake, Cochin backwaters and Korapuzha estuary are well known for their rich population of mud crabs. Realizing the imperative need to build up a strong scientific base for proper management and conservation of the resource and also to develop proper technologiesfor seed production and farming of mud crabs, a detailed study was undertaken on the mud crabs of Kerala coast and the results are described in the thesis. The thesis is presented in four chapters |
| Description: | School Of Marine Sciences Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3668 |
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| Dyuthi-T1555.pdf | (6.848Mb) |
| Abstract: | The present investigations confine to a study of the distribution of foraminifera in the estuarine environment and the interstial area of the sandy beaches of the south west coast of India with a view to correlate the distribution and the intensity of occurrence of the various species with hydrographic conditions and the substrate characteristics of the area. Studies on the foraminifera of the estuarine environment were carried out in the vembanad lake ,a major estuary in the south west coast of india extending for about 60km from cochin barmouth in the north to Alleppey in the south.Fortnightly collections of hydrographical data and grab samples of bottom deposit were made for a period of 2 years (july 1973 to june 1975) from fifteen stations chosen along the length of the lake. |
| Description: | School of marine sciences, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3319 |
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| Dyuthi-T1290.pdf | (6.972Mb) |
| Abstract: | Investigations on the fracture behaviour of polymer blends is the topic of this thesis. The blends selected are PP/HDPE and PS/HIPS. PP/HDPE blend is chosen due to its commercial importance and PS/HIPS blend is selected to study the transition from brittle fracture to ductile fracture.PP/HDPE blends were prepared at different compositions by melt blending at 180°C and fracture failure process was investigated by conducting notch sensitivity test and tensile test at different strain rates. The effects of two types of modifiers (particulate and elastomer) on the fracture behaviour and notch sensitivity of PP/HDPE blends were studied. The modifiers used are calcium carbonate, a hard particulate filler commonly used in plastics and Ethylene Propylene Diene Monomer (EPDM). They were added in 2%, 4% and 6% by weight of the blends.The study shows that the mechanical properties of PP/HDPE blends can be optimized by selecting proper blend compositions. The selected modifiers are found to alter and improve the fracture behaviour and notch sensitivity of the blends. Particulate fillers like calcium carbonate can be used for making the mechanical behaviour more stable at the various blend compositions. The resistance to notch sensitivity of the blends is found to be marginally lower in the presence of calcium carbonate. The elastomeric modifier EPDM produces a better stability of the mechanical behaviour. A low concentration of EPDM is sufficient to effect such a change. EPDM significantly improves the resistance to notch sensitivity of the blends. The study shows that judicious selection of modifiers can improve the fracture behaviour and notch sensitivity of PP/HDPE blends and help these materials to be used for critical applications.For investigating the transition in fracture behaviour and failure modes, PS/HIPS blends were selected. The blends were prepared by melt mixing followed by injection moulding to prepare the specimens for conducting tensile, impact and flexure tests. These tests were used to simulate the various conditions which promote failure.The tensile behaviour of unnotched and notched PS/HIPS blend samples were evaluated at slow speeds. Tensile strengths and moduli were found to increase at the higher testing speed for all the blend combinations whereas maximum strain at break was found to decrease. For a particular speed of testing, the tensile strength and modulus show only a very slight decrease as HIPS content is increased up to about 40%. However, there is a drastic decrease on increasing the HIPS content thereafter.The maximum strain at break shows only a very slight change up to about 40% HIPS content and thereafter shows a remarkable increase. The notched specimens also follow a comparable trend even though the notch sensitivity is seen high for PS rich blends containing up to 40% HIPS. The notch sensitivity marginally decreases with increase in HIPS content. At the same time, it is found to increase with the increase in strain rate. It is observed that blends containing more than 40% HIPS fail in ductile mode.The impact characteristics of PSIHIPS blends studied were impact strength, the energy absorbed by the test specimen and impact toughness. Remarkable increase in impact strength is observed as HIPS content in the blend exceeds 40%. The energy absorbed by the test specimens and the impact toughness also show a comparable trend.Flexural testing which helps to characterize the load bearing capacity was conducted on PS/HIPS blend samples at the two different testing speeds of 5mmlmin and 10 mm/min. The flexural strength increases with increase in testing speed for all the blend compositions. At both the speeds, remarkable reduction in flexural strength is observed as HIPS content in the blend exceeds 40%. The flexural strain and flexural energy absorbed by the specimens are found to increase with increase in HIPS content. At both the testing speeds, brittle fracture is observed for PS rich blends whereas HIPS rich blends show ductile mode of failure.Photoelastic investigations were conducted on PS/HIPS blend samples to analyze their failure modes. A plane polariscope with a broad source of light was utilized for the study. The coloured isochromatic fringes formed indicate the presence of residual stress concentration in the blend samples. The coverage made by the fringes on the test specimens varies with the blend composition and it shows a reducing trend with the increase in HIPS content. This indicates that the presence of residual stress is a contributing factor leading to brittle fracture in PS rich blends and this tendency gradually falls with increase in HIPS content and leads to their ductile mode of failure. |
| Description: | School of Engineering, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2625 |
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| Dyuthi-T0704.pdf | (5.609Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1152 |
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| Govindan T K 1983.PDF | (109.1Kb) |
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