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P. K. Saha , A. Bhattacharya , S. N. Ganguly

Abstract

Shorea robusta Gaertn. f. (Sal) seeds remain viable only for 10-days from the date of harvest under natural conditions. The non-viability is due to loss of moisture from the seed coat followed by cotyledon and embryo. Hairs present in the viable seed coat are lost in the non-viable ones. It is possible to store the seeds in, viable condition for two months after harvest at a temperature between l0-12°C. The seeds have been classified into four categoris on the basis of morphological characters. Absorption of water during germination is an important marker in identifying the seed viahility. Gibberellic acids (GA₁, GA₃, GA₅,. GA₁₃,) and indole acetic acid (IAA) in both free and conjugated forms which are present in viable seeds disappear in non-viable ones. The carbohydrates, proteins and acid phosphates which are also present in the viable seeds decline in the non-viable ones along with the denaturation of proteins In the non-viable seeds phenolics as well as fatty acids are formed which act as inhibitors of germination. The loss of moisture from the seed coat causes the loss of membrane integrity and this can be overcome by storing the seeds at cool temperature (10-12°C). Kinetin (0.01 mg/1 treatment is also effective.

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A. Basu ¹, P. K. Saha ², M. Sen ²

Affiliations
1 Department of Mathematics, Ananda Chandra College, Jalpaiguri 735101, IN
2 Department of Mathematics, North Bengal University, Darjeeling 734413, IN

Abstract

A tournament is a complete oriented graph and a tournament that is an interval digraph is an interval tournament. Interval tournaments have been characterized in terms of forbidden subtournaments. It has also been proved that a tournament with n-vertices is an interval tournament if and only if it has a transitive (n−1)-subtournament. We provide here an alternative proof of their characterizations. Our approach helps us to obtain other characterizations of interval tournaments. One of these characterizations is that a tournament is an interval tournament if and only if all of its 3-cycles have a common vertex. We then obtain another characterization in terms of three forbidden subdigraphs. Lastly we characterize the complement of an interval tournament in terms of two-clique circular-arc graphs.

Keywords

Interval Digraph, Interval Bigraph, Interval Tournament, Zero Partition, Transitive Tournament.

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P. K. Saha ¹, B. K. Lahiri ²

Affiliations
1 Department of Mathematics, University of North Bengal, Raja Rammohanpur, Darjeeling, West Bengal, IN
2 Department of Mathematics, University of Kalyani, Kalyani, West Bengal, IN

Abstract

Goffman and Waterman [S] introduced a new topology in the real number space and showed that the approximately continuous functions are continuous in this topology. They called it the density topology or in short d-topology. Subsequently, various properties of d-topology in the real number space were proved by various authors {See for example [6], [13], [14], [18]}. Martin [12] extended the concept of density topology in a measure space and proved some of its topological properties. The concept of density topology was further extended to topological group in [1].

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P. K. Saha ¹, R. K. Ghosh ¹

Affiliations
1 Mechanical Engineering Department, B. E. College, Howrah-711103, IN

Abstract

A numerical method had been used to determine the nonsteady-state temperature distributions in the billet during extrusion and to study the effects of ram speed, friction condition on temperature distribution. The necessary velocity, strain rate, and strain fields were obtained from visioplasticity experimental results. The speed of the billet was also considered in the heat conduction equation. Heat generation due to frictional work and deformation work was considered at a time. Average value of flow stress and average thermal properties of the billet material were used in the heat transfer equation. Heat generation and conduction were approximated in two consecutive steps during equal time increment Δt. The maximum temperature at a point inside the lead billet was found to be 82.14°C after 12.5 sees of extrusion with ambient temperature of 30°C and extrusion ratio=8.07, ram speed=0.042 cm/sec., coefficient of friction at the billet-container interface=0.10, coefficient of friction at die-material interface=0.577, die angle=45°. The procedure for determining the temperature distribution was programmed in FORTRAN IV Language and was run in TDC-316 Digital Computer.

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P. K. Saha ¹

Affiliations
1 Asansol Planning Organisation, IN

Abstract

The concept that organisms and their environment form a system of functional interdependence represent the view of most modern ecologists. In every natural situation the environment affects the organism present in it and the organisms in its turn affect the environment. Man is a very important element in his environment. He almost always has modifying influence over his environment and without proper regulation this influence often becomes destructive. Like other animals man must adjust with his environment for the survival of his species. Currently he is suffering from lack of such adjustments.

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P. K. Saha ¹

Affiliations
1 Bharat Heavy Electricals Limited, IN

Abstract

For non-corrosive fluids like steam, piping material used depends on the temperature of the fluid. Where a number of material grades may be considered, oxidation resistance, freedom from graphitisation, fabricability, weldability and economic availability determine which material grade should have preference for use. In general, use of good quality carbon steel has been restricted to 400°C. For higher temperatures, certain additional properties viz. creep strength and rupture strength come into consideration and these make it imperative to use alloy steel. In this sense, temperatures above 400°C may be considered to be high temperature for piping materials.

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P. K. Saha ¹

Affiliations
1 Bharat Heavy Electricals Limited, IN

Abstract

For non-corrosive fluids like steam, piping material used depends on the temperature of the fluid. Where a number of material grades may be considered oxidation resistance, freedom from graphitisation, fabricability, weldablllty and economic availability determine which material grade should have preference for use. In general, use of good quality carbon steel has been restricted to 400°C. For higher temperatures, certain additional properties viz. creep strength and rupture strength come into consideration and these make it imperative to use alloy steel. In this sense, temperatures above 400°C may be considered to be high temperature for piping materials.

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