Performance of 25m large mesh demersal trawl off Veraval, north west coast of India

Performance of a 25m large mesh demersal trawl, with 150mm mesh size in the fore parts of the trawl was evaluated in comparison with one boat high opening trawl of the Bay of Bengal Programme (BOBP) with 360 meshes of 160mm mesh size and 25.6m head rope length. An 8.2% increase in catch was obtained by 25m large mesh demersal trawl. The gear is comparatively cheaper, lighter in construction and offered better horizontal spread with significantly lower towing resistance. Commercial suitability of the gear for efficient harvesting of demersal fish resources of the region is discussed

A study of the effects of Acutalyn R

Call number: LD2668 .T4 1960 F7

Studies on the suitability of HDPE material for gill nets

The suitability of HDPE yarn and HDPE twine in place of nylon for gill nets has been studied. As regards total catch nylon gill net is found to be better than HDPE nets. However, statistical analysis of the catch in respect of quality fishes shows that HDPE yarn nets are equally efficient as nylon nets

Integrated TiO2 resonators for visible photonics

We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators with loaded quality factors of 2x10^4 for the visible wavelengths. The structures were fabricated in sputtered TiO2 thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser. Devices based on this material could serve as integrated optical elements as well as passive platforms for coupling to visible quantum emitters.Comment: 4 pages, 3 figure

Twisted split-ring-resonator photonic metamaterial with huge optical activity

Coupled split-ring-resonator metamaterials have previously been shown to exhibit large coupling effects, which are a prerequisite for obtaining large effective optical activity. By a suitable lateral arrangement of these building blocks, we completely eliminate linear birefringence and obtain pure optical activity and connected circular optical dichroism. Experiments at around 100-THz frequency and corresponding modeling are in good agreement. Rotation angles of about 30 degrees for 205nm sample thickness are derived.Comment: 6 pages, 4 figure

The effects of combined chemical treatments on the mechanical properties of three grades of sisal

Different grades of sisal fibres (S3, STOW, and SUG) were immersed in five different treatment solutions: sodium hydroxide (NaOH) for 24 h; silane for 24 h; and NaOH followed by silane for 6, 12, and 24 h. The treated fibres were tested for bonding strength using the micro-droplet method. It was established that NaOH and silane treatments improved bonding strength with the unsaturated polyester resin that was used. However, it can be concluded that NaOH followed by silane (each for 6 h) produced the highest bonding strength compared with the other combined treatments. This is most likely because of fibre erosion caused by the chemicals in the other treatments, which causes fibres to lose the ability to bond with the resin. Fibres treated with silane had the highest bonding strength. The tensile mechanical properties, characterised using the single-fibre test method according to the ASTM standard C1557-03 (2008), showed that the NaOH treatment improved ultimate tensile strength, while the silane treatment decreased ultimate tensile strength for all sisal grades. Nevertheless, the ultimate tensile strength was reduced when the duration of the combined treatments was increased. The highest results for the mechanical properties were obtained from the combined treatments of NaOH followed by silane (each for 6 h)

A Tale of two topologies: Woodward-Hoffmann rules at your fingertips!

A simple procedure for determining whether a pericyclic reaction is thermally allowed is described. The focus is on the potential aromaticity of the transition state of the process, which is inferred from the topological features of the interacting orbitals and the number of electrons involved

The Abel Inversion of Noisy Data Using Discrete Integral Transforms

The determination of a radially symmetric two-dimensional function from its one dimensional projection is known as Abel inversion. This finds applications in several fields of engineering and science including astronomy, image processing, plasma diagnostics and optics. One radial slice of the function, which completely specifies the two-dimensional function, is the inverse Hankel transform of the Fourier Transform of the projection. With the projection data available as a discrete signal, the Abel inversion can be performed using the discrete Fourier transform and the inverse Hankel transform. The existing techniques to compute inverse Hankel transforms are discussed and a modification to one of those methods is introduced and shown to yield reasonably accurate results with significantly fewer calculations. The efficient fast Fourier transform is used in the evaluation of both the transforms. Experimentally obtained projection data, which is usually noisy and off-center, is dealt with in the Fourier domain using a frequency domain filter and a maximum likelihood estimator derived from the assumed noise characteristics. The maximum likelihood estimator is used to estimate the Fourier transform of the properly centered data. Results of numerical experiments are given to verify the method. The proposed method is computationally more efficient than the existing curve-fitting methods for performing the Abel inversion of noisy data