Faculty of Sciences
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/1616
Mon, 27 Apr 2015 13:41:10 GMT2015-04-27T13:41:10ZExploration of Novel Organic Reactions Catalyzed by Nucleophilic Heterocyclic Carbenes (NHCs)
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4941
Exploration of Novel Organic Reactions Catalyzed by Nucleophilic Heterocyclic Carbenes (NHCs)
Sinu, C R; Vijay, Nair, G; Radhakrishnan, K V
The thesis entitled “Exploration of Novel Organic Reactions Catalyzed by
Nucleophilic Heterocyclic Carbenes (NHCs)” embodies the results of the
investigations carried out to explore the synthetic potential of N–heterocyclic carbenes
(NHCs) as organocatalyst towards various electrophiles for the synthesis of heterocyclic
and carbocyclic systems. Recent investigations in the generation of homoenolates by the
addition of NHCs to conjugated aldehydes have made it possible to study the reactivity of
this unique three carbon synthon.
Sat, 22 Nov 2014 00:00:00 GMThttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/49412014-11-22T00:00:00ZStudies on the use of Nanokaolin, MWCNT and Graphene in NBR and SBR
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4940
Studies on the use of Nanokaolin, MWCNT and Graphene in NBR and SBR
Preetha Nair, K; Dr.Rani, Joseph; Dr.Mathiazhagan, A
The current research investigates the possibility of using unmodified and modified nanokaolin, multiwalled carbon nanotube (MWCNT) and graphene as fillers to impart enhancement in mechanical, thermal, and electrical properties to the elastomers. Taking advantage of latex blending method, nanoclay, MWCNT and graphene dispersions, prepared by ultra sound sonication are dispersed in polymer latices. The improvement in material properties indicated better interaction between filler and the polymer.MWCNT and graphene imparted electrical conductivity with simultaneous improvement in mechanical properties. Layered silicates prepared by microwave method also significantly improve the mechanical properties of the nanocomposites. The thesis entitled ‘Studies on the use of Nanokaolin, MWCNT and Graphene in NBR and SBR’ consists of ten chapters. The first chapter is a concise introduction of nanocomposites, nanofillers, elastomeric matrices and applications of polymer nanocomposites. The state-of-art research in elastomer based nanocomposites is also presented. At the end of this chapter the main objectives of the work are mentioned. Chapter 2 outlines the specifications of various materials used, details of experimental techniques employed for preparing and characterizing nanocomposites. Chapter3 includes characterization of the nanofillers, optimsation of cure time of latex based composites and the methods used for the preparation of latex based and dry rubber based nanocomposites. Chapter4 presents the reinforcing effect of the nanofillers in XNBR latex and the characterization of the nanocomposites. Chapter5 comprises the effect of nanofillers on the properties of SBR latex and their characterization Chapter 6 deals with the study of cure characteristics, mechanical and thermal properties and the characterization of NBR based nanocomposites.
Chapter7 is the microwave studies of MWCNT and graphene filled elastomeric nanocomposites. Chapter 8 gives details of the preparation of layered silicates, their characterization and use in different elastomeric matrices. Chapter 9 is the study of mechanical properties of nanoclay incorporated nitrile gloves .Chapter 10 presents the summary and conclusions of the investigation.
Wed, 17 Jul 2013 00:00:00 GMThttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/49402013-07-17T00:00:00ZProperties of Equilibrium Distributions of Order n
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4939
Properties of Equilibrium Distributions of Order n
Preeth, M; Dr.Unnikrishnan Nair, N
The present work is intended to discuss various properties and reliability aspects of
higher order equilibrium distributions in continuous, discrete and multivariate cases, which contribute to the study on equilibrium distributions. At first, we have to study and consolidate the existing literature on equilibrium distributions. For this we need some basic concepts in reliability. These are being discussed in the 2nd chapter, In Chapter 3, some identities connecting the failure rate functions and moments of residual life of the univariate, non-negative continuous equilibrium distributions of higher order and that of the baseline distribution are derived. These identities are then used to characterize the generalized Pareto model, mixture of exponentials and gamma distribution. An approach using the characteristic functions is also discussed with illustrations. Moreover, characterizations of ageing classes using stochastic orders has been discussed. Part of the results of this chapter has been reported in Nair and Preeth (2009). Various properties of equilibrium distributions of non-negative discrete univariate random variables are discussed in Chapter 4. Then some characterizations of the geo- metric, Waring and negative hyper-geometric distributions are presented. Moreover, the ageing properties of the original distribution and nth order equilibrium distribu- tions are compared. Part of the results of this chapter have been reported in Nair, Sankaran and Preeth (2012). Chapter 5 is a continuation of Chapter 4. Here, several conditions, in terms of stochastic orders connecting the baseline and its equilibrium distributions are derived. These conditions can be used to rede_ne certain ageing notions. Then equilibrium distributions of two random variables are compared in terms of various stochastic orders that have implications in reliability applications.
In Chapter 6, we make two approaches to de_ne multivariate equilibrium distribu-
tions of order n. Then various properties including characterizations of higher order equilibrium distributions are presented. Part of the results of this chapter have been reported in Nair and Preeth (2008). The Thesis is concluded in Chapter 7. A discussion on further studies on equilib- rium distributions is also made in this chapter.
Sun, 01 Jun 2014 00:00:00 GMThttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/49392014-06-01T00:00:00ZA study on semigroup action on fuzzy subsets, inverse fuzzy automata and related topics
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4938
A study on semigroup action on fuzzy subsets, inverse fuzzy automata and related topics
Pamy, Sebastian; Dr.Johnson, T P
This thesis comprises five chapters including the introductory chapter. This includes a brief introduction and basic definitions of fuzzy set theory and its applications, semigroup action on sets, finite semigroup theory, its application in automata theory along with references which are used in this thesis. In the second chapter we defined an S-fuzzy subset of X with the extension of the notion of semigroup action of S on X to semigroup action of S on to a fuzzy subset of X using Zadeh's maximal extension principal and proved some results based on this. We also defined an S-fuzzy morphism between two S-fuzzy subsets of X and they together form a category S FSETX. Some general properties and special objects in this category are studied and finally proved that S SET and S FSET are
categorically equivalent. Further we tried to generalize this concept to the action of a fuzzy semigroup on fuzzy subsets. As an application, using the above idea, we convert a _nite state automaton to a finite fuzzy state automaton. A classical automata determine whether a word is accepted by the automaton where as a _nite fuzzy state automaton determine the degree of acceptance of the word by the automaton. 1.5. Summary of the Thesis 17 In the third chapter we de_ne regular and inverse fuzzy automata, its construction, and prove that the corresponding transition monoids are regular and inverse monoids respectively. The languages accepted by an inverse fuzzy automata is an inverse fuzzy language and we give a characterization of an inverse fuzzy language. We study some of its algebraic properties and prove that the collection IFL on an alphabet does not form a variety since it is not closed under inverse homomorphic images. We also prove some results based on the fact that a semigroup is inverse if and only if idempotents commute and every L-class or R-class contains a unique idempotent. Fourth chapter includes a study of the structure of the automorphism group of a deterministic faithful inverse fuzzy automaton and prove that it is equal to a subgroup of the inverse monoid of all one-one partial fuzzy transformations on the state set. In the fifth chapter we define min-weighted and max-weighted power
automata study some of its algebraic properties and prove that a fuzzy automaton and the fuzzy power automata associated with it have the same transition monoids.
The thesis ends with a conclusion of the work done and the scope of further study.
Mon, 16 Jun 2014 00:00:00 GMThttp://dyuthi.cusat.ac.in:80/xmlui/handle/purl/49382014-06-16T00:00:00Z