Cepstrum Analysis: An Advanced Technique in Vibration Analysis of Defects in Rotating Machinery

Conventional frequency analysis in machinery vibration is not adequate to find out accurately defects in gears, bearings, and blades where sidebands and harmonics are present. Also such an approach is dependent on the transmission path. On the other hand, cepstrum analysis accurately identifies harmonics and sideband families and is a better technique available for fault diagnosis in gears, bearings, and turbine blades of ships and submarines. Cepstrum represents the global power content of a whole family of harmonics and sidebands when more than one family of sidebands are presents at the same time. Also it is insensitive to the transmission path effects since source and transmission path effects are additive and can be separated in cepstrum. The concept, underlying theory and the measurement and analysis involved for using the technique are briefly outlined. Two cases were taken to demonstrate advantage of cepstrum technique over the spectrum analysis. An LP compressor was chosen to study the transmission path effects and a marine gearbox having two sets of sideband families was studied to diagnose the problematic sideband and its severity

Handbook of Marine Prawns of India

Central Marine Fisheries Research Institute realized the importance of crustaceans as an exportable resource and started concentrating on prawn fisheries research and development since 1960s. CMFRI conducted a 'Symposium on Crustacea' in collaboration with the Marine Biological Association of India (MBAI) in 1965 to get an idea on the existing information on the biology and fisheries of Crustaceans. The Institute also published 'Bulletin 14' entitled 'Prawn Fisheries of India' in 1969 which brought to light the complete information on taxonomy, biology and fisheries of the commercial species of prawns in general and penaeid prawns in particular. Since then many studies were conducted on various aspects of prawn fisheries during the last 40 years. The prawn landings increased from 62,767 t forming 9.2% of the total marine fish landings in 1961 to 4,60,028 t forming 12% of the marine fish landings in 2011. The sea food exports gradually increased from 15,732 t valued at Rs.3.92 crores in 1961-62 to 6,12,641 t valued at Rs.8363.53 crores by 2006-07 and to 8,13,091 t valued at Rs. 12,901.47 crores in 2010-2011. Frozen shrimp continued to be the major export item accounting for 51.35% of the total foreign exchange realizations during 2010-11

Efficacy of Enrofloxacin in the Treatment of Recurrent Pyoderma in Dogs

Dogs with a history of more than three episodes of skin infections in a period of one year were selected for a study on recurrent pyoderma. Oral enrofloxacin along with appropriate simultaneous medication for the underlying associated conditions were chosen as therapy for recurrent pyoderma in dogs. Response to therapy was excellent in all the cases. Improvement was noticed by 12 to 20 days and 20 to 26 days in recurrent superficial and deep pyoderma respectively. Relapse occurred in one dog by 45 days due to re-introduction of allergic food. Enrofloxacin proved to be an effective, safe and convenient antibiotic for the treatment of recurrent pyoderma in dogs

Prawn culture in salt pans in East Godavari district, Andhra pradesh

The paper presents the results of two prawn culture experiments conducted in the salt pans of Andhra Pradesh. The first experiment was conducted ia the salt pans of Neellarevu during June- December 1974. Two adjacent pans of 0.61 ha (pond A) and 0.48 ha (pond B) were stocked with juveniles otPenaeus monodon and P. indicus of 65 mm mean lengths. In these ponds salinity varied from 21.97 ppt to 47.39 ppt and temperature from 29.2°C to 35.0°C. At harvest in December, the mean size oiP. monodon was 165.4 mm and that of P. indicus was 140.7 mm. The production rate of prawns for the 6 months period was 164 kg/ha and 189 kg/ha respectively in the two ponds. The net profit was at the rate of Rs. 980/ha in pond A and Rs. 1113/ha in pond B. In the second experiment conducted at Lakshmipathipuram, 9470 juveniles of P. monodon, mean length at 54.2 mm, were stocked in a salt pan reservoir of 0.26 ha provided with a box type sluice gate in December 1976. The pond water temperature varied from 25.5°C to 31.0°C and salinity from 21.27 ppt to 45.39 ppt. Rice bran at a rate of 13-16% of body weight of the prawn was given as supplementary feed. Growth rate was found to be low in higher salinity (38.72—45.39 ppt). At harvest, P. monodon had mean length of 123.4 mm with about 79.3% survival. After 168 days the yield was 259 kg/ha. A net profit of Rs. 1388 was gained per hectare in 6 months without hampering the salt production

Spawning concentrations of the sardine, Sardinella gibbosa (Bleeker), off the north Andhra Coast in March - April 1969

Adult Sardinella gibbosa in pre-spawning and spawning stages were observed in March 1969 in Waltair - Kakinada region from catches made 15-20 km from shore. Plankton collections made during this period off Kakinada contained eggs which have been assigned to S. gibbosa based on circumstantial evidence and resemblances. Most of the stomachs of 5. ^/'66oM examined during the period were either empty or contained very little food. These indicate that there was extensive spawning of the species off the North Andhra coast in March-April 1969

Stock assessment of the penaeid prawn Metapenaeus monoceros Fabricius along the Indian coast

The annual average production oi Metapenaeus monoceros during 1985-89 was 10 286 tonnes, nearly 7.2% of the penaeid prawn landings in the country. Tlie west coast accounted for 71.2% and the east coast for the rest. Among the maritime states, Maharashtra ranked first in production (27.2%) followed by Kamataka (22.3%) and Andhra Pradesh (21.3 %). The estimates of von Benalanffy growth parameters, L" and K (annual) were 180 mm and 1.8 for males, and 210 mm and 1.8 for females. This prawn attained a size of 149 mm and 173 mm in males and females, respectively, at the end of 1 year. The instantaneous total mortality coefficient (Z) ranged between 4.28 and 8.05 in males, and between 4.17 and 6.33 in females. Natural mortality coefficient (M) was 1.8 in both the sexes. Yield per recruit studies indicated that for an age of 0.59 year at first capture the fishery generated a steadily increasing yield up to 10 000 tonnes for an annual effort of 1 578 000 boat trips (16 670 000 fishing hours) at which the annual fishing mortality (F) is 3.76 and the exploitation ratio (E) is 0.67. Beyond this level of exploitation the increase in yield was only marginal. Even though the average aimual yield during 1985-89 was marginally lower than the maximum sustainable yield (MSY) of 10 993 t, the catch during 1987 and 1988 exceeded MSY level. Hence the desirability of maintaining the effort at the present level to obtain sustainable yields is mentioned

Stock assessment of Penaeus spp. off the east coast of India

Penaeid prawn Sandingi increased from 20 744 tonnes in 1980 to 37 410 tonnes in 1986 and then declined to 31 029 tonnes in 1989 (average 29 642 tonnes), Prawns of the genus Penaeus supported good fishery all along the east coast of India forming 40% of the penaeid prawn landings. lite three commercially important species, viz. Penaeus indicus, P. semisulcatus and P. monodon, contributed 5 849, 4 387 and 639 tonnes, respectively, to the annual penaeid prawn landings of the east coast. Tamil Nadu with annual landings of 7 880 tonnes was the major contributor to the Penaeus landings of the east coast followed by Andhra Pradesh (1 639 tonnes), Orissa (387 tormes), Pondicherry (119 tonnes) and large trawlers (850 tonnes). Past work on biological aspects such as postlarval immigration, juvenile emigration, i'ood and feeding habits and maturation and spawning has been reviewed. Age and growth parameters of P.indicus and P. semisulcatus were estimated by employing ELEFAN I method. Population estimates of P.indicus and P. semisulcatus showed very high fishing mortality and declining yidd while those of P. monodon indicated scope for increasing the landings. HSY estimates for P. indicus, P. semisulcatus and P. monodon are S 961 tonnes, 4 681 tonnes and 652 tonnes respectively. Species-wise and state-wise catch quotas have been suggested based on MSY and the present landings

Magnitude of lobster resources of India

Lobsters inhabit our tropical waters in different concentrations in some parts of our coasts. The average annual catch of lobsters during the 10 year period of 1975-84 was 1763 toni.es forming 0.82% among the crustaceans ano 0.12 % in the total marire fish landings. Of these 73.56 % was from Gujarat and Maharashtra and 19.45 % from Tamil Nadu. Of the 6 species of spiny lobsters recorded, only 3 of them ana one species of slipper lobster support the fishery of this country. The catches of Panulirus polyphagus and Thenus orientalis were substantial forming about 46.71% and 46.44% respectively. The catch of Panulirus homarus was poor contributing to only 5.89% while that of Panulirus ornatus was almost negligible, being 0.96%. The magnitude of the catch for P. homarus and P. ornatus is so small that they should not be exploited more than the existing rate from the present fishing grounds. Either new grounds have to be found or the population should be raised by culture practices to meet the demand of the market

Packages of Practices for Sustainable, Ecofriendly Mariculture (Land-based Saline Aquaculture and Seafarming)

The problems of fast growing human population and protein deficit, particularly in the developing countries continue to exert pressure on the fisheries resources available for exploitation in the wild water bodies. The increasingly limited opportunities in the capture fisheries sector have generated considerable interest in aquaculture

Review on cephalopod resources, biology and stock assessment in Indian seas

Cephalopods are fished from the seas around India from very early times and at present contribute one of the most important exploited marine fishery resources oj the country (between 4 and 5% of the all India production). The production, which remained at very low level up to the early seventies, has shown a remarkable increase crossing the 1,00,000 tonne mark in 1994. The taxonomy, biology and stock assessment of the various exploited species have been studied since the early seventies by the CMFRI. Studies indicate that uplo 1994 tlie exploitation has remained within rational limits in almost all maritime states. The recent rapid increase in production warrants close monitoring of this short-lived resource from the viewpoint of Judicious management