NOPR Collection:

An adaptive scheme for processing multitrace marine seismic data

2000-06-01T00:00:00Z

Title: An adaptive scheme for processing multitrace marine seismic data Authors: Srivastava, Kirti Abstract: A deconvolution method based on the adaptive linear filtering technique has been developed for processing multitrace time-varying seismic data. In this adaptive algorithm the combined filter coefficients are being continuously updated as the seismic trace is being processed. The convergence factor of the adaptive algorithm obtained from the combined trace information is a major controlling parameter that regulates both speed and stability of the adaptive process. This constant convergence factor has been used to process the multitrace information. The developed method has been tested on a field sample of marine seismic data from the western continental margin of India. Results reveal that the methodology is effective in comparison to the conventional method of predictive deconvolution in removing the water bottom multiples. Page(s): 106-110

Computation of diffusion coefficients for water of Ghauthami Godavari estuary using one-dimensional advection-diffusion model

2000-06-01T00:00:00Z

Title: Computation of diffusion coefficients for water of Ghauthami Godavari estuary using one-dimensional advection-diffusion model Authors: Jyothi, D; Murty, T Y Ramana; Sarma, V V; Rao, D P Abstract: An analysis of salinity, salt budget and diffusion coefficients based on the salinity data of Gauthami Godavari estuary for three different months (Nov. '95 Jan. '96, April '96) representing different seasons has been carried out. Diffusion coefficients vary quite randomly with distance between 90 - 4050 m²/s for consecutive months during Nov. '95 - Jan. '96 and between 10-869 m²/s for Jan. '96 - April. '96. The mean values of diffusion coefficients are found to be 1510 m²/s for consecutive months during Nov. '95 - Jan. '96, 174 m²/s for Jan. '96-April '96 and are attributed to the river run-off. The undulations in diffusion coefficients reflect the topographic features. The estuarine salt budget shows an increase of salt content by 62% from Nov. '95 - Jan. '96 and 32% from Jan. '96 - April. Page(s): 185-187

Growth of hatchery raised banana shrimp Penaeus merguiensis (de Man) (Crustac:Decapoda) juveniles under different salinity

2000-06-01T00:00:00Z

Title: Growth of hatchery raised banana shrimp Penaeus merguiensis (de Man) (Crustac:Decapoda) juveniles under different salinity Authors: Saldahana, Christinta M; Achuthankutty, C T Abstract: In order to optimise the conditions for improved production of the banana shrimp Penaeus merguiensis in the farms, effect of salinity on growth and survival was studied for 4 weeks using hatchery reared juveniles. Survival was very poor in salinity < 15 ppt. Weight progressively increased with increase in salinity to record a significantly high growth (P<0.05) in 40 ppt salinity (8.5 times the initial weight in 4 weeks). The results indicate that this species is suitable for cultivation in high saline waters. Page(s): 179-180

Effect of different salting methods on the nutritional and sensory characteristics of hilsa (Hilsa ilisha)

2000-06-01T00:00:00Z

Title: Effect of different salting methods on the nutritional and sensory characteristics of hilsa (Hilsa ilisha) Authors: Rahman, M A; Hossain, M A; Mansur, M A Abstract: A study was conducted to evaluate the overall quality in terms of proximate composition, rancidity, NPN (non protein nitrogen) content, protein digestibility, and sensory characteristics of hilsa (Hilsa ilisha) salted by different methods at ambient temperature (26-30°C). The salting methods included, salting of hilsa with dry crystalline salt, salting with previously prepared unsaturated brine (25g salt in 100ml water w/v) and salting with previously prepared saturated brine (dissolving salt in water until saturation). The hilsa salted with saturated brine showed longest shelf life (12 weeks) while the products by other two methods had shelf lives of 8 weeks only. Rancidity was maximum in the dry salted hilsa. The nonprotein nitrogen content was also highest in the dry salted fish . However, the sensory characteristics of the dry salted hilsa was the best among the three different types, although the sensory characteristics were altered after 8 weeks. Hilsa salted with saturated brine retained its sensory characteristics up to 12 weeks. Despite some biochemical changes and sensory characteristics, hilsa salted with saturated brine is good and ensures a longer shelf life. Page(s): 171-175