ഊര്‍ജ്ജാവശ്യകത കുറഞ്ഞ മത്സ്യബന്ധനരീതികള്‍ (Low energy fishing techniques)

Fishing is hard hit by the rise in fuel prices. This is especially true of trawlers. Because of high fuel consumption of trawlers, there has been considerable development in the use of large diameter propellers and nozzles and large reduction gears to improve efficiency.Consequent on the introduction of mechanised boats and modem fishing methods in the late fifties, fishing attained the status of an industry. The widespread use of outboard motors in the eighties brought in marked changes in the traditional sector. The deplojonent of outboard motors enabled the country crafts to go deeper and farther for fishing

A study of vortex diodes at low Reynolds number.

Knowledge of the flow characteristics of geometrically similar vortex diodes of different dimensions is essential in establishing the possible application of miniaturized vortex diodes in the medical field. The objective of this study is to find out whether Reynolds number and Eulers number are sufficient to describe the vortex diode performance and to experimentally verify the results obtained by finite element analysis. The steady-state, incompressible, three-dimensional, confined flow of water through vortex diodes at low Reynolds numbers was numerically and experimentally investigated. Three geometrically similar Plexiglas vortex diodes were constructed and tested for flows at low Reynolds numbers. The pressure drop across each diode was measured for various flow rates. Static characteristics of the vortex diodes for both forward and reverse flows are presented. The results indicate that in the Reynolds number range of 200 $\u3c$ Re $\u3c$ 3000 there is no noticeable scale effect on the static characteristics of the vortex diode. The Reynolds number is defined by the average axial velocity in the axial pipe and its diameter. The results also indicate that, due to the possible influence of viscous effects, the performance ratios are relatively small compared to those obtained at higher Reynolds numbers. There is also good agreement between the numerical and experimental results.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1992 .M275. Source: Masters Abstracts International, Volume: 31-04, page: 1912. Thesis (M.A.Sc.)--University of Windsor (Canada), 1992

Quantum Hall Effect on the Hyperbolic Plane

In this paper, we study both the continuous model and the discrete model of the Quantum Hall Effect (QHE) on the hyperbolic plane. The Hall conductivity is identified as a geometric invariant associated to an imprimitivity algebra of observables. We define a twisted analogue of the Kasparov map, which enables us to use the pairing between $K$-theory and cyclic cohomology theory, to identify this geometric invariant with a topological index, thereby proving the integrality of the Hall conductivity in this case.Comment: AMS-LaTeX, 28 page

Twisted K-theory and K-theory of bundle gerbes

In this note we introduce the notion of bundle gerbe K-theory and investigate the relation to twisted K-theory. We provide some examples. Possible applications of bundle gerbe K-theory to the classification of D-brane charges in non-trivial backgrounds are discussed.Comment: 29 pages, corrected typos, added references, included new section on twisted Chern character in non-torsion cas

Cyclic cocycles on twisted convolution algebras

We give a construction of cyclic cocycles on convolution algebras twisted by gerbes over discrete translation groupoids. For proper \'etale groupoids, Tu and Xu provide a map between the periodic cyclic cohomology of a gerbe-twisted convolution algebra and twisted cohomology groups which is similar to a construction of Mathai and Stevenson. When the groupoid is not proper, we cannot construct an invariant connection on the gerbe; therefore to study this algebra, we instead develop simplicial techniques to construct a simplicial curvature 3-form representing the class of the gerbe. Then by using a JLO formula we define a morphism from a simplicial complex twisted by this simplicial curvature 3-form to the mixed bicomplex computing the periodic cyclic cohomology of the twisted convolution algebras. The results in this article were originally published in the author's Ph.D. thesis.Comment: 39 page

Mesh selectivity for spotted seer, Scomberomorus guttatus (Bloch & Schneider)

An attempt has been made to evolve a suitable mesh size for the commercially significant size group of S. guttatus. To obtain maximum sustainable yield taking biological factors also into consideration, 52 mm mesh bar nets are suggested for exploiting the fishery on both the East coasts of India

Preliminary observations on the lunar and tidal influences on the catches of seer by gill nets

The paper deals with the lunar and tidal influences on the catches of seer by gill nets. The landings during full moon and new moon nights, during low and high tides and during different quarters of the lunar month for three fishing seasons are discussed

Statistical properties of Klauder-Perelomov coherent states for the Morse potential

We present in this paper a realistic construction of the coherent states for the Morse potential using the Klauder-Perelomov approach . We discuss the statistical properties of these states, by deducing the Q- and P-distribution functions. The thermal expectations for the quantum canonical ideal gas of the Morse oscillators are also calculated