Magnetometer-Based Measurements of Stray Current Distribution on Cathodically Protected Gas Transmission Pipeline

Currents on gas pipelines are known to arise from intentional sources such as impressed current systems used for cathodic protection and from unintended and often unknown sources including local transit systems, power stations and a range of telluric sources. Under some conditions these stray currents can be large enough to present a potential threat to the integrity of the pipeline through accelerated local corrosion. This is even true for nominally cathodically protected systems if the magnitudes of the stray currents are sufficiently large.</p

PEMFC Fault Diagnosis, Modeling, and Mitigation

This paper introduces fault diagnosis and separation, mitigation, and modeling of a proton exchange membrane fuel cell (PEMFC). Experimental tests of a single PEMFC were performed during this study. Flooding and drying faults were implemented to be detected from the cell voltage and impedance response of the cell. The impedance response at low frequency was used to identify the cause of the fault. The slope of the magnitude and/or the negative phase response of the cell impedance at low frequency were observed to allow separation of a fault. A cell impedance model based on resistive capacitive (C model) and resistive constant-phase-element (CPE model) circuits is developed. The CPE model has a better approximation of the cell impedance. However, the C model is easy to implement since it is well known in most simulation tools (MATLAB/Simulink or PSpice). A power electronic control is designed and tested to mitigate the faults. Pulsing the cell current at low frequency was seen to increase the cell power by 8% during drying

Culture of the sea bass Lates calcarifer

Studies on the growth of Lates calcarifer cultured in coastal ponds and net cages in the three different places at Tuticorin showed an increase of 16.2-23.2 mm/ 18.6- 53.2 g/ month at Karapad, 21.1-29.8mm/19.3- 36.3 g / month at Veppalodai in coastal ponds and 21.6-32.4 mm/ 31.4-55.0 g / month in a net cage in the Tuticorin Bay. The growth in Karapad pond, where supplementary feed was provided was better than in Veppalodai pond. The highest growth rate was obtained in net cage culture at Tuticorin Bay. Length-frequency analysis of samples from commercial catch reveal a faster growth in the wild than in the culture systems. The better growth in the brackishwater culture and in the wild is attributed to the lower salinity and better live feed availability in brackishwater. In the pond system, the growth can be improved by maintaining proper water exchange so as to maintain the salinity equivalent to open sea/bay/ brackishwaters and by providing supplementary feed

Further observations on polyculture of finfishes and Prawns in saltwater ponds and in a net-pen at Mandapam

The paper deals with the results of polyculture experiments with milkfish. mullets, Sillago and prawns in salt water ponds and in a netpen in the coastal waters of Palk Bay at Mandapam, during the period 1979-82. The growth of mullet and Sillago was better in the netpen than in the pond, whereas milkfish showed better growth in the pond. Significant differences in production from fertilized and unfertilized ponds have not been noticed, the result of which is attributed to poor soil conditions of the farm. Mullets sharply reacted to low levels of oxygen in ponds. During 1979-80 period, in experiment I, the production per hectare was 671.1 kg for Chanos chanos, 68.9 kg for Valamugil seheli, 593. 3 kg for Liza macrolepis and 31.1 kg for Penaeus indicus, thereby recorded the total of 1364.4 kg. In experiment II, the production was 1286. 7 kg for C. chanos, 551.1 kg for V. seheli md 26.7 kg for Sillago sihama with the total of 1864.5 kg. In 1980-81 experiment, the total production was 1600 kg with the combination of 1266.7 kg C. chanos and 333.3 kg V. seheli in the fertilized pond and 1422.2 kg with the combination of 1205.5 kg of C. chanos and 216.7 kg of V. seheli in the unfertilized pond. During 1981-82 period, the total production was 1377.8 kg in which C. chanos showed 1288.9 kg and V. seheli 88.9 kg in the fertilized pond, and in the unfertilized pond it was 1469.9 kg with 1405.5 kg of C. chanos and 64.4 kg of V. seheli

Holographic Imaging of Crowded Fields: High Angular Resolution Imaging with Excellent Quality at Very Low Cost

We present a method for speckle holography that is optimised for crowded fields. Its two key features are an iterativ improvement of the instantaneous Point Spread Functions (PSFs) extracted from each speckle frame and the (optional) simultaneous use of multiple reference stars. In this way, high signal-to-noise and accuracy can be achieved on the PSF for each short exposure, which results in sensitive, high-Strehl re- constructed images. We have tested our method with different instruments, on a range of targets, and from the N- to the I-band. In terms of PSF cosmetics, stability and Strehl ratio, holographic imaging can be equal, and even superior, to the capabilities of currently available Adaptive Optics (AO) systems, particularly at short near-infrared to optical wavelengths. It outperforms lucky imaging because it makes use of the entire PSF and reduces the need for frame selection, thus leading to higher Strehl and improved sensitivity. Image reconstruction a posteriori, the possibility to use multiple reference stars and the fact that these reference stars can be rather faint means that holographic imaging offers a simple way to image large, dense stellar fields near the diffraction limit of large telescopes, similar to, but much less technologically demanding than, the capabilities of a multi-conjugate adaptive optics system. The method can be used with a large range of already existing imaging instruments and can also be combined with AO imaging when the corrected PSF is unstable.Comment: Accepted for publication in MNRAS on 15 Nov 201

Preliminary experiments on the culture of grey mullets at Mandapam

The paper deals with experiments on the culture of grey mullets Valamugil seheli, Liza vaigiensis and Liza macrolepis in monoculture and polyculture systems in seawater ponds and a pen erected in coastal waters at Mandapam

Studies on diurnal variations in the occurrence of grey mullet seed at Mandapam

In order to study the diurnal variations in the occurrence of mullet seed, collections were made With a drag net once in a fortnight 3 to 6 days after the full moon and new moon days from august 1978 to July 1979 and also 2-3 days before full and new moon days from August 1979 to October 1979 in addition to the regular collections made on other days, at Theedai near Mandapam along the Palk bay

Major and minor fisheries harbours of India. 6. The fisheries harbour and fishery at Tuticorin

The Tuticorin Fisheries Harbour Is one of the old and important fishery ports of India located on the southern Tamil Nadu coast and on the western side of the Gulf of Mannar. Now owing to its commercial and economic importance from the marine fisheries point of view it is considered as one of the major fisheries harbours on the east coast of India. The harbour was constructed at a cost of Rs. 2.1 crore in 1968 in a total area of 17 acres, out of which the berthing area is 2.7 acres. This harbour has a berthing facility to accommodate 450 medium sized mechanised wooden trawlers. The total length of the jetty is 800 m and the depth in the area of berthing is 3m

Threadfin breams and lizard fish resources in the shelf waters of the Indian EEZ

The regional and seasonal distribution and abundance of threadfin breams and lizard fish are presented as revealed by the bottom trawling operations of FORV Sagar Sampada during cruises 56-91 (1989 and 1992). The threadfin breams occurred in 49 and lizard fish in 25% of the total number of bottom trawhng stations surveyed. The most productive grounds for threadfin breams were located in the southwest coast between 8° and 15° N latitudinal zones, with the area 11775° yielding the highest average catch rate of 1794 kg/hr. Very high congregation and concentration of threadfin breams, composed mainly of Nemipterus mesoprion and N. japonicus, was observed in the southwest in 41- 80 m depth zones during southwest monsoon period. Lizard fish resources, composed mainly of Saurida tumbil and S. undosquamis were also relatively more dominant in the southwest coast than along the east coast and in the EEZ of Andaman-Nicobar islands. The size distribution of N. japonicus and A', mesoprion showed that smaller modal groups were dominant in shallower depth zones. The potential yield of threadfin breams in the southwest zone was estimated to be 2.05 x 10