Studies on a syntax based approach for translation between structurally different languages and the development of a prototype for Malayalam to English translation

This thesis summarizes the results on the studies on a syntax based approach for translation between Malayalam, one of Dravidian languages and English and also on the development of the major modules in building a prototype machine translation system from Malayalam to English. The development of the system is a pioneering effort in Malayalam language unattempted by previous researchers. The computational models chosen for the system is first of its kind for Malayalam language. An in depth study has been carried out in the design of the computational models and data structures needed for different modules: morphological analyzer , a parser, a syntactic structure transfer module and target language sentence generator required for the prototype system. The generation of list of part of speech tags, chunk tags and the hierarchical dependencies among the chunks required for the translation process also has been done. In the development process, the major goals are: (a) accuracy of translation (b) speed and (c) space. Accuracy-wise, smart tools for handling transfer grammar and translation standards including equivalent words, expressions, phrases and styles in the target language are to be developed. The grammar should be optimized with a view to obtaining a single correct parse and hence a single translated output. Speed-wise, innovative use of corpus analysis, efficient parsing algorithm, design of efficient Data Structure and run-time frequency-based rearrangement of the grammar which substantially reduces the parsing and generation time are required. The space requirement also has to be minimised

”Investigations on The Finite Size Effects of Some Inverse Spinels and Studies on Their Composites Based on Nitrile Rubber”

In the present study, nano particles of NiFe3O4, I_.l()5Feg5O4 and CoFegO4 are prepared by sol gel method. By appropriate heat treatments, particles of different grain sizes are obtained. The structural, magnetic and electrical measurements are evaluated as a function of grain size and temperature. NiFe3O4 prepared in the ultrafine regime are then incorporated in nitrile rubber matrix. The incorporation was carried out according to a specific recipe and for various loadings of magnetic fillers. The cure characteristics, magnetic properties, electrical properties and mechanical properties of these elastomer blends are carried out. The electrical permittivity of all the rubber samples in the X — band are also conducted

Studies on laser induced optogalvanic effect in certain gas discharges

Electrical gas discharges have been the subject of numerous investigations from the last century due to their growing interest in technological and fundamental applications. Absorption of electromagnetic radiation by a gas discharge result into a change in electrical impedance due to a significant perturbations in the steady state population of excited levels and the degree of ionization. This change in impedance produced by resonant absorption of radiation is known as optogalvanic COG) effect. where as that is produced by injecting electrons in to the discharge by photoelectric emission is usually known as photoemission optogalvanic (FOG) effect. With the development of lasers and sophisticated electronic equipment. these effects have established their importance in analytical and spectroscopic measurements. The present thesis deals with the work carried out by the author in the field optogalvanic effect during the past few years at the Department of Physics in Cochin University of Science| and "Fechnology. The results and the observation are summarized in nine chapters and the references to the literature is made at the end of each chapter

Studies on High- Tc Superconductors with Inequivalent Conducting Layers

The thesis deals with the study of super conducting properties of layered cuprates within the frame work of a modified Lawrence-Doniach (LD) model. The thesis is organized in seven chapters. Chapter I is a survey of the phenomena and theories of conventional superconductivity which can serve as a springboard for launching the study of the new class of oxide superconductors and it also includes a chronological description of the efforts made to overcome the temperature barrier. Chapter II deals with the structure and properties of the copper oxide superconductors and also the experimental constraints on the theories of high te:::nperature superconductivity. A modified Lawrence-Doniach type of phenomenological model which forms the basis of the presnt study is also discussed. In chapter III~ the temperature dependence of the upper critical field both parallel and perpendicular to the layers is determined and the results are compared with d.c. magnetization measurements on different superconducting compoilllds. The temperature and angular dependence of the lower critical field both parallel and perpendicular to the layers is also discussed. Chapters IV, V and VI deal with thermal fluctuation effects on superconducting properties. Fluctuation specific heat is studied in chapter IV. Paraconductivity both parallel and perpendicular to the layers is discussed in chapter V. Fluctuation diamagnetism is dealt with in chapter VI. Dimensional cross over in the fluctuation regime of all these quantities is also discussed. Chapter VII gives a summary of the results and the conclusions arrived at.

Studies On Some New Transition Metai. Complexes Of The Schiff Bases Derived From Ouinoxaline - 2 - Carboxaldehyde

This thesis deals with the synthesis, characterisation and catalytic activity studies of some new transition metal complexes of the Schiff bases, derived from quinoxaline—2—carboxaldehyde. The model complexes derived from specially designed and synthesised Schiff bases help us to understand the chemistry of biological systems. Schiff bases derived from heterocyclic aldehydes like quinoxaline-2-carboxaldehyde provide great structural diversity during complexation. The Schiff bases synthesised in the present study ' are quinoxaline—2—carboxa.lidene-2-aminophenol (QAP). quinoxaline—2carboxaldehyde semicarbazone (QSC), quinoxaline-2—carboxalidene—o— phenylenediamine (QOD) and quinoxaline-2-carboxalidene-2-furfurylamine (QFA). The elucidation of the structure of these complexes is done using conductance, magnetic susceptibility measurements. infrared, UV—Vis and EPR spectral studies.

" Studies on Laser induced Phatothermal Phenomena in Selected Organic Compounds and Fullerenes"

In the pre—laser era it was difficult to believe that the optical properties of a medium depend upon the intensity of the radiation incident on it. The basis for this conclusion is that the electric field strength associated with the conventional light sources used before the advent of lasers was much smaller than (103 V/cm) the field sttrengths of atomic or interatomic fields (2 107 —- 10” V/cm). The radiation with such low intensity is not able to affect atomic fields to the extent of changing optical parameters. The invention of laser in 1960 was a turning point. The high degree of coherence of the laser radiation provides high spatial concentration of optical power. With the availability of the femtosecond lasers it has become possible to get extremely high peak powers 2 1013 W/cmz). At such high fields, the relationship between electric ‘polarization P and the electric field strength E ceases to be linear and several nonlinear effects begin to occur. Nonlinear absorption, a branch of nonlinear optics, refers to the interaction between radiation and matter accompanied by absorption of more than one photon. Nonlinear absorption has acquired great importance after the invention of high power lasers. One of the objectives of the present work is to investigate the nonlinear absorption processes occurring in fullerene, selected organic solvents and laser dyes. Fullerenes and laser dyes were chosen because of their highly nonlinear behaviour. Fullerenes, the most beautiful among molecules, offer fascinating field of research owinglto their significant structural properties. As toluene, benzene and carbon disulphide are themost widely used solvents for fullerenes, it seems important to study the nonlinear properties of these liquids as well. Like fullerenes, laser dyes also possess highly delocalized 7r electrons which are responsible for their nonlinear absorption. Dye lasers were the fulfillment of an experimenter’s pipe dream - to have a laser that is easily tunable over a wide range of wavelengths. A better understandingof the photophysical properties of laser dyes can significantly enhance the development and technology of dye lasers. We studied the nonlinear absorption properties of two rhodamine dyes to have some insight into their nonlinear optical properties.

“Studies on short polyester fiber - polyurethane elastomer composite with different interfacial bonding agents”

The work presented in this thesis is regarding the development and evaluation of new bonding agents for short polyester fiber - polyurethane elastomer composites. The conventional bonding system based on hexamethylenetetramine, resorcinol and hydrated silica was not effective as a bonding agent for the composite, as the water eliminated during the formation of the RF resin hydrolysed the urethane linkages. Four bonding agents based on MDI/'I‘DI and polypropyleneglycol, propyleneglycol and glycerol were prepared and the composite recipe was optimised with respect to the cure characteristics and mechanical properties. The flow properties, stress relaxation pattern and the thermal degradation characteristics of the composites containing different bonding agents were then studied in detail to evaluate the new bonding systems. The optimum loading of resin was 5 phr and the ratio of the -01 to isocyanate was 1:1. The cure characteristics showed that the optimum combination of cure rate and processability was given by the composite with the resin based on polypropyleneglycol/ glycerol/ 4,4’diphenylmethanediisocynate (PPG/GL/MDI). From the rheological studies of the composites with and without bonding agents it was observed that all the composites showed pseudoplastic nature and the activation energy of flow of the composite was not altered by the presence of bonding agents. Mechanical properties such as tensile strength, modulus, tear resistance and abrasion resistance were improved in the presence of bonding agents and the effect was more pronounced in the case of abrasion resistance. The composites based on MDI/GL showed better initial properties while composites with resins based on MDI/PPG showed better aging resistance. Stress relaxation showed a multistage relaxation behaviour for the composite. Within the-strain levels studied, the initial rate of relaxation was higher and the cross over time was lesser for the composite containing bonding agents. The bonding agent based on MDI/PPG/GL was found to be a better choice for improving stress relaxation characteristics with better interfacial bonding. Thennogravimetirc analysis showed that the presence of fiber and bonding agents improved the thennal stability of the polyurethane elastomer marginally and it was maximum in the case of MDI / GL based bonding agents. The kinetics of degradation was not altered by the presence of bonding agents

“Studies on new base materials for microcellular soles"

The most important part of any footwear is the sole (or sole and heel) which withstands all the hannful external factors such as rouglmess of the ground or road, sharp objects, thorns and stones, heat, dampness and cold during walking. The properties desirable in soling material, therefore, would be 1. lightness 2. resistance to wear and tear for long service life 3. flexibility/softness for wearing comfort 4. thennal insulation Rubber soling surpasses all other soling materials in better performance and lower cost. Because MC sole is soft and very light, and has good abrasion resistance, flex properties and set behaviour it has become very popular all over the world and demand for better quality product is ever increasing. Due to the traditional approach adopted by the footwear industry in foot wear design, the rubber based footwear export surprisingly contributes only a small percentage. The essence of success for any industry lies in the expansion of the export market. Microcellular soles are manufactured for the last three decades without much change in the traditional design and colour pattern. In recent years domestic customers have also started demanding better quality products. In view of the changing taste of the customer and growing competition from other countries, substantial improvement in the export potential will require new base materials for regular or fashion rubber based footwears. The main objective of the present study is to develop new base materials for making MC soles with good quality, viz., light weight, durability and bright colours

Studies on the induction of variation through in vitro culture in Jatropha curcas L

Given the economic importance of Jatropha curcas, and its limited availability in the wild, it would be desirable to establish plantations ofthe tree so as to obtain assured supply of raw material for extraction of phytochemicals, and seeds for production of biodiesel. However both seed propagation as well as propagation by cuttings is unsatisfactory in this tree species. Seeds have poor viability and are genetically heterozygous leading to genetic variability in terms of growth, biomass, seed yield, and oil content. Stern cuttings have poor roots and the trees are easily uprooted. Tissue culture techniques could possibly be gainfully employed in the propagation of elite plants ofJaIropha. When plant tissue is passaged through in vitro culture, there is possibility of induction of variations. An estimation of somaclonal variability is useful in a determination of culture protocols. Molecular markers could be employed to estimate the amount of variations induced in callus and regenerants by different honnonal combinations used in culture. In this context the present study aims to develop an in vitro propagation protocol for the production of plantlets and to evaluate the variation induced in callus and regenerants in comparison with mother plant by the use of molecular markers and by studying phytochemicals and bio active compounds present in callus and regenerated plants

Studies On In Vitfio Production Of Secondary Metabolites From Medicinal Plants

In the light of the very huge demand for natural ephedrine and pseudoephidrine, a search for an angiosperm plant containing the alkaloid ephedrine was made and could locate Sida spp. of malvaceae family. Sida is a large genus of, herbs and shrubs distributed throughout the tropics. About a dozen species occur in India. The medicinally important species known are S.rhombrfolia S.cordata and S.spinosa (Anon, 1972). Among the various species, S.rh0mbIfolia is the most widely used one in the traditional system of medicine. An attempt was made in the present study to develop an ideal bioprocess for the in vitro production of ephedrine from the cell culture system of Sida rhombrfolia Linn. ssp. retusa. The callus and suspension culture were initiated and attempts were made to enhance the yield positively by employing various strategies like mutagenesis, immobilization and addition of precursors, elicitors and penneabilizing agents.

Studies On The Effect Of Laser Radiation And Other Mutagens On Plants

The effect of lasers of three wavelengths in the visible region - 476, 488 and 514 nm on mitotic and meiotic cell divisions, growth, yield and activity of specific enzymes were studied in two taxonomically diverse plant species — A/lium cepa L. and Vicia faba. The effect of laser exposures was compared with the effect of two physical mutagens (Gamma and Ultraviolet radiations) and two chemical mutagens (Ethyl Methane Sulphonate and Hydroxyl amine). The study indicated that lasers could be mutagenic causing aberration in the mitotic and meiotic cell divisions while also producing changes in the growth and yield of the plants. Lasers of higher wavelengths 488 and 514 nm caused aberrations in the early stages of mitotic cell division whereas lasers of lower wavelengths (476 nm) caused more aberrations in the later stages of mitotic cell division. Laser exposure of 488 nm wavelength at power density 400 mW induced higher mitotic and meiotic aberrations and also induced higher pollen sterility than lasers of 476 and 514 nm. The frequency of mitotic aberrations induced by lasers was lesser than that caused by y-irradiation but comparable to that induced by EMS and HA. Lasers cause mutations in higher frequencies than UV. Lasers had a stimulatory effect on growth and yield in both plant species. This stimulatory effect of lasers on germination could not however be correlated to the activity of amylase and protease, the key enzymes in seed gennination. Enzymes such as peroxidase and catalase, involved in scavenging of free oxygen radicals often produced by irradiation, did not show increased activity in laser irradiated samples. Further studies are required for elucidating the exact mechanisms by which lasers cause mutations

Biodegradability Studies on LDPE-Starch Blends using Amylase-Producing Vibrios

Low-density polyethylene, (LDPE) was mixed with two grades of tapioca starch–lowgrade and high-grade. Various compositions were prepared and mechanical and thermal studies performed. The biodegradability of these samples was checked using a culture medium containing Vibrios (an amylase-producing bacteria), which was isolated from a marine benthic environment. The soil burial test and reprocessability of these samples were checked. The studies on biodegradability show that these blends are partially biodegradable. These low-density polyethylene-starch blends are reprocessable without sacrificing much of their mechanical properties

Studies On Strength Characteristics Of Soil Mixed With Bio-Waste

Researches are always in quest for finding innovative methods for ground improvement using sustainable and environmental friendly solutions. Theproduction of large quantity of biowastes all over the world faces serious problems of handling and disposal. Coir pith is a biowaste from coir industry and sugarcane baggase is another biowaste obtained after extractingjuice from sugar cane. So the present study is an investigation into the effect of coir pith and sugarcane baggase on some geotechnical properties of red earth. The investigation includes study on variation of properties such as O.M.C, maximum dry density, C.B.R. values,unconfined compressive strength and permeability when these materials are included in soil. Several conclusions are arrived at, on the basis of the experiments conducted and it may be helpful for predicting the behavior of such soil matrix

Magnetic and processability studies on rubber ferrite composites based on natural rubber and mixed ferrite

Polycrystalline single phasic mixed ferrites belonging to the series Ni1−xZnxFe2O4 for various values of x have been prepared by conventional ceramic techniques. Pre-characterized nickel zinc ferrites were then incorporated into a natural rubber matrix according to a specific recipe for various loadings. The processability and cure parameters were then determined. The magnetic properties of the ceramic filler as well as the ferrite loaded rubber ferrite composites (RFC) were evaluated and compared. A general equation for predicting the magnetic properties was also formulated. The validity of these equations were then checked and correlated with the experimental data. The coercivity of the RFCs almost resemble that of the ceramic component in the RFC. Percolation threshold is not reached for a maximum loading of 120 phr (parts per hundred rubber by weight) of the filler. These studies indicate that flexible magnets can be made with appropriate magnetic properties namely saturation magnetisation (Ms) and magnetic field strength (Hc) by a judicious choice of x and a corresponding loading. These studies also suggest that there is no possible interaction between the filler and the matrix at least at the macroscopic level. The formulated equation will aid in synthesizing RFCs with predetermined magnetic

Studies on the optical band gap and cluster size of the polyaniline thin films irradiated with swift heavy Si ions

Polyaniline thin films prepared by RF plasma polymerisation were irradiated with 92MeV Si ions for various fluences of 1 1011, 1 1012 and 1 1013 ions/cm2. FTIR and UV–vis–NIR measurements were carried out on the pristine and Si ion irradiated polyaniline thin films for structural evaluation and optical band gap determination. The effect of swift heavy ions on the structural and optical properties of plasma-polymerised aniline thin film is investigated. Their properties are compared with that of the pristine sample. The FTIR spectrum indicates that the structure of the irradiated sample is altered. The optical studies show that the band gap of irradiated thin film has been considerably modified. This has been attributed to the rearrangement in the ring structure and the formation of CRC terminals. This results in extended conjugated structure causing reduction in optical band gap