Analytical Investigations 0n Collapse of Cylindrical Submarine Shells

Submarine hull structure is a watertight envelope, under hydrostatic pressure when in operation. Stiffened cylindrical shells constitute the major portion of these submarine hulls and these thin shells under compression are susceptible to buckling failure. Normally loss of stability occurs at the limit point rather than at the bifurcation point and the stability analysis has to consider the change in geometry at each load step. Hence geometric nonlinear analysis of the shell forms becomes. a necessity. External hydrostatic pressure will follow the deformed configuration of the shell and hence follower force effect has to be accounted for. Computer codes have been developed based on all-cubic axisymmetric cylindrical shell finite element and discrete ring stiffener element for linear elastic, linear buckling and geometric nonIinear analysis of stiffened cylindrical shells. These analysis programs have the capability to treat hydrostatic pressure as a radial load and as a follower force. Analytical investigations are carried out on two attack submarine cylindrical hull models besides standard benchmark problems. In each case, the analysis has been carried out for interstiffener, interdeepframe and interbulkhead configurations. The shell stiffener attachment in each of this configuration has been represented by the simply supported-simply supported, clamped-clamped and fixed-fixed boundary conditions in this study. The results of the analytical investigations have been discussed and the observations and conclusions are described. Rotation restraint at the ends is influential for interstiffener and interbulkhead configurations and the significance of axial restraint becomes predominant in the interbulkhead configuration. The follower force effect of hydrostatic pressure is not significant in interstiffener and interdeepframe configurations where as it has very high detrimental effect on buckling pressure on interbulkhead configuration. The geometric nonlinear interbulkhead analysis incorporating follower force effect gives the critical value of buckling pressure and this analysis is recommended for the determination of collapse pressure of stiffened cylindrical submarine shells.

Marine yeasts as source of single cell protein and immunostimulant for application in penaeid prawn culture systems

The study revealed the potential of marine yeasts as a source of single cell protein and immunostimulant for prawns. Prawns fed with the selected marine yeasts were showing more growth compared to the control feed and commercial feed. Yeasts being rich with proteins, vitamins and carbohydrates serve as a growth promoter for prawns as being evidenced in this study. The better performance of marine yeasts, D. hansenii S8 and S100 and C. tropicalis S186 compared to S. cerevisiae S36 as a feed supplement is worth investigating. Besides being a rich nutritional source, yeasts act as immunostimulants by virtue of its high carbohydrate (Beta, 1-3 glucan) and RNA content. Beta, 1-3 glucan, a cell wall component of yeasts /fungi is the most commonly used immunostimulant in aquaculture. The present study shows that even the whole cell yeast could serve as a good immunostimulant when supplied through diet. Extraction of Beta-1,3 glucan results in the removal of nutrients like proteins, vitamins etc. from the cell biomass.Utilization of the yeast biomass as such in the diet would help perform a dual role as nutritional component and immunostimulant for aquaculture applications.

Fabrication of Electrochemical Sensors for the Determination of Pharmaceuticals

Voltammetric sensors are an important class of electrochemical sensors in which the analytical information is obtained from the measurement of current obtained as a result of electrochemical oxidation/reduction.This current is proportional to the concentration of the analyte.Chemically modified electrodes(CMEs) have great significance as important analytical tools for the electrochemical determination of pharmaceuticals.The modification of electrode results in efficient determination of electro-active biomolecules at very lower potential without its major interferences.The operation mechanism of CMEs depends on the properties of the modifier materials that are used to promote selectivity towards the target analytes.Modified electrodes can be prepared by deposition of various compounds such as organic compounds ,conducting polymers,metal oxides,etc. on the various electrode surfaces.The thesis presents the development ,electrochemical characterization and analytical application studies of eight voltammetric sensors developed for six drugs viz.,Ambroxol,Sulfamethoxazole,PAM Chloride, Lamivudine,Metronidazole and Nimesulide.The modification techniques adopted as part of the present work include Multiwalled Carbon Nanotube(MWCNT) based modification.Electropolymerisation and Gold Nanoparticle (AuNP) based modifications.

Development of Best Practices for Ship Recycling Processes

Ship recycling has been considered as the best means to dispose off an obsolete ship. The current state of art of technology combined with the demands of sustainable developments from the global maritime industrial sector has modified the status of erstwhile ‘ship breaking’ involving ship scrap business to a modern industry undertaking dismantling of ships and recycling/reusing the dismantled products in a supply chain of pre owned product market by following the principles of recycling. Industries will have to formulate a set of best practices and blend them with the engineering activities for producing better quality products, improving the productivity and for achieving improved performances related to sustainable development. Improved performance by industries in a sustainable development perspective is accomplished only by implementing the 4E principles, ie.,. ecofriendliness, engineering efficiency, energy conservation and ergonomics in their core operations. The present study has done a comprehensive investigation into various ship recycling operations for formulating a set of best practices.Being the ultimate life cycle stage of a ship, ship recycling activities incorporate certain commercial procedures well in advance to facilitate the objectives of dismantling and recycling/reusing of various parts of the vessel. Thorough knowledge regarding these background procedures in ship recycling is essential for examining and understanding the industrial business operations associated with it. As a first step, the practices followed in merchant shipping operations regarding the decision on decommissioning have been and made available in the thesis. Brief description about the positioning methods and important preparations for the most feasible ship recycling method ie.,. beach method have been provided as a part of the outline of the background information. Available sources of guidelines, codes and rules & regulations for ship recycling have been compiled and included in the discussion.Very brief summary of practices in major ship recycling destinations has been prepared and listed for providing an overview of the global ship recycling activities. The present status of ship recycling by treating it as a full fledged engineering industry has been brought out to establish the need for looking into the development of the best practices. Major engineering attributes of ship as a unique engineering product and the significant influencing factors on her life cycle stage operations have been studied and added to the information base on ship recycling. Role of ship recycling industry as an important player in global sustainable development efforts has been reviewed by analysing the benefits of ship recycling. A brief synopsis on the state of art of ship recycling in major international ship recycling centres has also been incorporated in the backdrop knowledgebase generation on ship recycling processes.Publications available in this field have been reviewed and classified into five subject categories viz., Infrastructure for recycling yards and methods of dismantling, Rules regarding ship recycling activities, Environmental and safety aspects of ship recycling, Role of naval architects and ship classification societies, Application of information technology and Demand forecasting. The inference from the literature survey have been summarised and recorded. Noticeable observations in the inference include need of creation of a comprehensive knowledgebase on ship recycling and its effective implementation in the industry and the insignificant involvement of naval architects and shipbuilding engineers in ship recycling industry. These two important inferences and the message conveyed by them have been addressed with due importance in the subsequent part of the present study.As a part of the study the importance of demand forecasting in ship recycling has been introduced and presented. A sample input for ship recycling data for implementation of computer based methods of demand forecasting has been presented in this section of the thesis.The interdisciplinary nature of engineering processes involved in ship recycling has been identified as one of the important features of this industry. The present study has identified more than a dozen major stake holders in ship recycling having their own interests and roles. It has also been observed that most of the ship recycling activities is carried out in South East Asian countries where the beach based ship recycling is done in yards without proper infrastructure support. A model of beach based ship recycling has been developed and the roles, responsibilities and the mutual interactions of the elements of the system have been documented as a part of the study Subsequently the need of a generation of a wide knowledgebase on ship recycling activities as pointed out by the literature survey has been addressed. The information base and source of expertise required to build a broad knowledgebase on ship recycling operations have been identified and tabulated. Eleven important ship recycling processes have been identified and a brief sketch of steps involved in these processes have been examined and addressed in detail. Based on these findings, a detailed sequential disassembly process plan of ship recycling has been prepared and charted. After having established the need of best practices in ship recycling initially, the present study here identifies development of a user friendly expert system for ship recycling process as one of the constituents of the proposed best practises. A user friendly expert system has been developed for beach based ship recycling processes and is named as Ship Recycling Recommender (SRR). Two important functions of SRR, first one for the ‘Administrators’, the stake holders at the helm of the ship recycling affairs and second one for the ‘Users’, the stake holders who execute the actual dismantling have been presented by highlighting the steps involved in the execution of the software. The important output generated, ie.,. recommended practices for ship dismantling processes and safe handling information on materials present onboard have been presented with the help of ship recycling reports generated by the expert system. A brief account of necessity of having a ship recycling work content estimation as part of the best practices has been presented in the study. This is supported by a detailed work estimation schedule for the same as one of the appendices.As mentioned earlier, a definite lack of involvement of naval architect has been observed in development of methodologies for improving the status of ship recycling industry. Present study has put forward a holistic approach to review the status of ship recycling not simply as end of life activity of all ‘time expired’ vessels, but as a focal point of integrating all life cycle activities. A new engineering design philosophy targeting sustainable development of marine industrial domain, named design for ship recycling has been identified, formulated and presented. A new model of ship life cycle has been proposed by adding few stages to the traditional life cycle after analysing their critical role in accomplishing clean and safe end of life and partial dismantling of ships. Two applications of design for ship recycling viz, recyclability of ships and her products and allotment of Green Safety Index for ships have been presented as a part of implementation of the philosophy in actual practice.

DNA Interaction and Catalytic Activity Studies of Some New Transition Metal Complexes of Schiff Bases Derived from Quinoxaline

In this thesis we report the synthsis and characterisation of new transition metal complexes of Pd(II),Cu(II),Ru(II) and Ir(III) of Schiff bases derived from quinoxaline-2-carboxaldehyde/3-hydroxyquinoxaline-2-carboxaldehyde and 5-aminoindazole.6-aminoindazole or 8-aminoquinoline.The complexes have been characterised by spectral and analytical data.Pd(II) and Cu(II) form square planar complexes and Ru(III) and Ir(III) form ctahedral complexes with these Schiff bases.The DNA binding properties of theses synthesised complexes have been studied by various methods including electronic absoption spectroscopy,cyclic voltammetry,different pulse voltammetry and circular dichroism spectra were used.Gel electrophoresis experiments were also performed to investigate the DNA cleavage of theses complexes.Furthermore Ru(III) and Ir(III) complexes find application as oxidation and hydogenation catalsts. The studies on catalytic activities has been presented.The metal complexes presented in this thesis assure significance as they contribute to the development of new DNA binding agents and antibacterial and anticancer drugs.

Thermo-Structural Analysis of 3D Composites

Three dimensional (3D) composites are strong contenders for the structural applications in situations like aerospace,aircraft and automotive industries where multidirectional thermal and mechanical stresses exist. The presence of reinforcement along the thickness direction in 3D composites,increases the through the thickness stiffness and strength properties.The 3D preforms can be manufactured with numerous complex architecture variations to meet the needs of specific applications.For hot structure applications Carbon-Carbon(C-C) composites are generally used,whose property variation with respect to temperature is essential for carrying out the design of hot structures.The thermomechanical behavior of 3D composites is not fully understood and reported.The methodology to find the thermomechanical properties using analytical modelling of 3D woven,3D 4-axes braided and 3D 5-axes braided composites from Representative Unit Cells(RUC's) based on constitutive equations for 3D composites has been dealt in the present study.High Temperature Unidirectional (UD) Carbon-Carbon material properties have been evaluated using analytical methods,viz.,Composite cylinder assemblage Model and Method of Cells based on experiments carried out on Carbon-Carbon fabric composite for a temparature range of 300 degreeK to 2800degreeK.These properties have been used for evaluating the 3D composite properties.From among the existing methods of solution sequences for 3D composites,"3D composite Strength Model" has been identified as the most suitable method.For thegeneration of material properies of RUC's od 3D composites,software has been developed using MATLAB.Correlaton of the analytically determined properties with test results available in literature has been established.Parametric studies on the variation of all the thermomechanical constants for different 3D performs of Carbon-Carbon material have been studied and selection criteria have been formulated for their applications for the hot structures.Procedure for the structural design of hot structures made of 3D Carbon-Carbon composites has been established through the numerical investigations on a Nosecap.Nonlinear transient thermal and nonlinear transient thermo-structural analysis on the Nosecap have been carried out using finite element software NASTRAN.Failure indices have been established for the identified performs,identification of suitable 3D composite based on parametric studies on strength properties and recommendation of this material for Nosecap of RLV based on structural performance have been carried out in this Study.Based on the 3D failure theory the best perform for the Nosecap has been identified as 4-axis 15degree braided composite.

Process Optimization for Mass Production of Marine Yeast Candida sp. S 27 and its Nutritional Characterization

The main source of protein for human and animal consumption is from the agricultural sector, where the production is vulnerable to diseases, fluctuations in climatic conditions and deteriorating hydrological conditions due to water pollution. Therefore Single Cell Protein (SCP) production has evolved as an excellent alternative. Among all sources of microbial protein, yeast has attained global acceptability and has been preferred for SCP production. The screening and evaluation of nutritional and other culture variables of microorganisms are very important in the development of a bioprocess for SCP production. The application of statistical experimental design in bioprocess development can result in improved product yields, reduced process variability, closer confirmation of the output response to target requirements and reduced development time and overall cost.The present work was undertaken to develop a bioprocess technology for the mass production of a marine yeast, Candida sp.S27. Yeasts isolated from the offshore waters of the South west coast of India and maintained in the Microbiology Laboratory were subjected to various tests for the selection of a potent strain for biomass production. The selected marine yeast was identified based on ITS sequencing. Biochemical/nutritional characterization of Candida sp.S27 was carried out. Using Response Surface Methodology (RSM) the process parameters (pH, temperature and salinity) were optimized. For mass production of yeast biomass, a chemically defined medium (Barnett and Ingram, 1955) and a crude medium (Molasses-Yeast extract) were optimized using RSM. Scale up of biomass production was done in a Bench top Fermenter using these two optimized media. Comparative efficacy of the defined and crude media were estimated besides nutritional evaluation of the biomass developed using these two optimized media.

Transition metal complexes of quinoxaline based Schiff base ligands: Synthesis,characterization and catalytic activity study

Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.The convenient route of synthesis and thermal stability of Schiff base complexes have contributed significantly for their possible applications in catalysis,biology,medicine and photonics.Significant variations in cataltytic activity with structure and type are observed for these complexes.The thesis deals with synthsis and characterization of transition metal complexes of quinoxaline based Schiff base ligands and their catalytic activity study.The Schiff bases synthesized in the present study are quinoxaline-2-carboxalidine-2-amino-5-methylphenol,3-hydroxyquinoxaline-2-carboxalidine-2-amino-5-methylphenol,quinoxaline-2-aminothiophenol.They provide great structural diversity during complexation.To the best of our knowledge, the transition metal complexes of quinoxaline based Schiff bases are poorly utilised in academic and industrial research.

Investigations on Dezincification of Brass and Epoxy Coated Brass

Brasses are widely used as constructional materials in marine environment due to their anticorrosive,antifouling and mechanical properties.However, its resistance to corrosion and fouling may vary according to local marine environmental condition and the seasons.The dezincification of brass is one of the forms of selective corrosion which has attracted the attention of researchers for the last two decades.Many of the dezincification mechanistic studies have been performed in noncomplex media and hence their conclusions cannot be extended to esturine water,which is of great significance since brass is extensively used in marine environment.Inhibited α brasses are largely immune to dezincication and the effect of tin and arsenic addition to α/beta brasses is not so reliable in controlling the dezincification. There have been many cases of dezincification in duplex brasses in both freshwater and seawater.Though there is some protection methods such as inhibitors,electro deposition and electro polymerization,there is no reliable method of inhibiting the dezincification of two-phase brass.Organic coatings are effectively used for the protection metals due to their capacity to act a physical barrieer between the metal surface and corrosive environment.Hence,pure epoxy coating is selected for this as it has antocorrosiion effect on brass.The dezincification behaviour of brass of the present study has been highlighted in terms of corrosion rate,weight gain/loss,corrosion current and polarization resistence,open circuit potential,dezincification factor. The marine fouling as biomass on brass was assessed and presented in this thesis, The physicochemical properties of estuarine water were correlated with corrosion behaviour of brass.The deterioration of the brass subjected to the effect of estuarine water was also investigated as a measure of loss in mechanical properties such as tensile strength,yield strength,percntage elongation and percentage reduction in area.To validate dezincification data,visual observation,spot analysis,surface morphology before and after removal of corrosion products and corrosion product analysis were performed.The dezincification behavior of epoxy coated brass of the present study has beenhighlighted in terms of corrosion rate ,weight gain/loss,corrosion current and polarization resistance,open circuit potential.dezincification factor.The marine fouling as biomass on epoxy coated brass subjeted to the effect of estuarine water was also investigated as ameasure of loss in mechanical properties such as tensile strength,percentage elongation and percentage reduction in area.The results of dezincification behavior of brass and epoxy coated brass in Cochin estuary water has been presented and discussed.Attempt has been made to correlate the dezincification behavior of brass with epoxy coated brass.

Biochemical Effects of Different Phenolic Compounds on Oreochromis Mossambicus (Peters)

Dept.of Marine Biology,Microbiology & Biochemistry,Cochin University of Science and Technology

Modification of Short Fibre Reinforced pp and HDPE Using Nanosilica

The present study was undertaken to prepare nanosilica by a simple cost effective means and to use it as a potential nanomodifier in thermoplastic matrices and to develop useful composites. Nanosilica was prepared from sodium silicate and dilute hydrochloric acid by polymer induced crystallization technique under controlled conditions. The silica surface was modified by silane coupling agent to decrease the agglomeration and thus to increase the reinforcement with polymer. The pristine nanosilica and modified nanosilica were used to make nano-micro hybrid composites. Short glass fibres and nylon fibres were used as microfillers. The hybrid nanocomposites based on Polypropylene (PP) and High density poly ethylene (HOPE) are prepared. The mechanical, thermal, crystallization and dynamic mechanical properties of the composites are evaluated.

Optimisation of the Mechanical Properties of HDPE/PP Blends and Their Recyclable Composites

This study was undertaken in order to upgrade blends of HDPE and PP, two of the most widely used standard plastics so as to widen their application spectrum. Dicumyl peroxide was used as the modifier for the upgradation. Optimum concentration of dicumyl peroxide required for modification was detennined by measurement of mechanical, rheological, thermal and morphological properties. Selected blends were used to prepare recyclable composites with nylon clothes by compression moulding. The composites were characterized by measurement of mechanical and thermal properties. The composites were recycled and the mechanical propertics of the recycled material were determined.

Development of novel surface coatings based on acrylic copolymers

The present study describes the preparation of Vinyl acetate-Butyl acrylate copolymer lattices of varying compositions and solid contents by semicontinuous emulsion polymerization method. This copolymer lattices were used as binder to develop a new surface coating formulation. The properties of this surface coating were improved by using nano TiO2 colloidal sol as a pigment. Antimicrobial activity of surface coatings was improved by the addition of carboxymethyl chitosan as biocide. Uniformly dispersed tyre crumb was used to give a mat finish to the coating. The mechanical properties adhesive properties, thermal properties etc. of the coatings are presented in thesis.

Algal blooms and zooplankton standing crop along the southwest coast of India

Dept. of Marine Biology, Microbiology and Biochemistry,CUSAT

Studies on Simple and Encapsulated Transition Metal Complexes of Schiff Bases Derived from Diaminonaphthalene

Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.In the present study we have synthesized some new Mn(II),Co(II) and Cu(II) complexes of Schiff bases derived from 1,8-diaminonaphthalene.Even though we could not isolate theses Schiff bases (as they readily cyclise to form the perimidine compounds),we were able to characterize unequivacally the complexes synthesized from these compounds as complexes of Schiff Bases. We Synthesized three perimidine derivatives ,2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine,2-(2,3-dihydro-1H-perimidin-2-yl)-6-methoxyphenol and 4-(2,3-dihyro-1H-perimidin-2-yl)-2-methoxyphenol by the condensation of 1,8-diaminonaphthalene with quinoxaline-2-carboxaldehyde,2- hydroxy-3-methoxybenzaldehyde or 4-hydroxy-3-methoxybenzaldehyde respectively.Theses compounds were used as precursor ligands for the preparation of Schiff base complexes.The complexes were characterized by using elemental analysis ,conductance and magnetic susceptibility measuremets ,infrared and UV-Visible spectroscopy ,thermogravimetric analysis and EPR spectroscopy .We also encapsulated the complexes in zeolite Y matrix and these encapsulated complexes were also characterized. We have also tried theses complexes as catalysts in the oxidation of cyclohexanol and decomposition of hydrogen peroxide.