The "karikkadi" fishery of Kerala

Parapenaeopsis stylifera, (called 'Karikkadi Chemmeen' ) is the most important species of prawn contributing to the commercial fishery of Kerala coast. An experimental shrimp trawling conducted for a period of two years has shown that during the non-monsoon period (September/October to May) most of the shrimp stocks occupy the coastal waters within the 20 m depth contour. With the commencement of southwest monsoon and the consequent changes in the environmental conditions, the prawns leave the inshore areas in large numbers to the deeper zones. The wide annual fluctuations observed at important centres, the occurrence of juvenile prawns in large quantities noticed quite often in the fishery, call for proper management and conservation measures

Response of Dome-enclosed Box-type Structure to Underwater Explosion

In the development of underwater sensor systems, the sensor arrays are configured for different shapes like cylindrical, rectangular and spherical depending on the requirement. The rectangular shaped box–type structure discussed here has both top and bottom ends open. Flanges stiffen the top and bottom ends, and gussets are used to connect the flanges with the structure. In this paper, the box-type structure is subjected to non-contact underwater explosion in a shock tank to study the peak free field pressure on the structure. To simulate the actual conditions, the structure is placed in free flooded area and covered with a dome. The free-field peak pressure on the dome and structure are plotted with time. The measured pressure curves are in agreement with the empirical predictions reported in literature. It is concluded that around 85 per cent of the shock impulse acting on the dome is transmitted to the box-type structure. The dome and box-type structure withstood the explosive load, thereby validating their design.Defence Science Journal, 2013, 63(4), pp.381-385, DOI:http://dx.doi.org/10.14429/dsj.63.213

Nonlinear Behaviour of Perforated Plate with Lining

Perforated plate with lining has a construction of plate with perforation and a lining plate welded together to form a single plate. This type of plate is used as an acoustic sonar dome. Perforated plate with lining (PPL) is prone to stress concentration and subsequently such structural system falls into the large strain category. Experimental investigation on PPL is carried out in the present study to determine the static deflection of the plate. Numerical method is also followed for geometric nonlinear analysis using finite element method as an iterative interactive procedure. The deflection obtained from the numerical method is 8 per cent less than that obtained from experimental method. From numerical analysis, von Mises stress and maximum principal stress is also estimated to understanda bout the failure mode characteristics of PPL.Defence Science Journal, 2012, 62(4), pp.248-251, DOI:http://dx.doi.org/10.14429/dsj.62.92

A new educational software tool for robust control design using the QFT method

ABSTRACT We present a new educational software tool for robust control design based on the Quantitative Feedback Design (QFT) method. This is a graphical design methodology for systems with large parametric uncertainty, which has been successfully applied to many complex practical problems. The software tool is implemented in Matlab and may be used to introduce students to robust control methods via small and medium-size design applications. The software is a library of programmable M-files with open access to users and is intended as a test-bed for developing new techniques in this area and for automating parts of the design procedure, such as loop-shaping. A simple design problem is used to illustrate the main features of the software

Fishery and biology of Plesionika quasigrandis Chace, 1985 off Sakthikulangara, south-west coast of India

The fishery and biology of Plesionika quasigrandis Chace, 1985 from Sakthikulangara Fishing Harbour was studied for the period 2006-2008. The average annual catch was 2400 t, forming 28% of the total deep sea shrimp landings at Sakthikulangara. August to November was the most productive period in terms of catch and catch rate. The growth parameters L∞ and K y-1 for males and females were 124 mm, 0.7 and 130 mm, 0.8 respectively. The growth performance index (φ’) and t0 were 4.032, -0.0036 and 4.131, -0.00275 for males and females, respectively with a longevity of 5 years. Recruitment pattern was bimodal with two peaks, one in March and the other in June. The relationship between total length (TL) and total weight (W) revealed an isometric growth in case of females and allometric growth in males. The length at recruitment (Lr) and length at 50% capture (Lc50) was 73; 84.8 mm (males) and 78; 93.4 mm (females), respectively which corresponded to an age (tc) of 1.6 years. The natural mortality, fishing mortality, total mortality, exploitation ratio, exploitation rate and Emax were 0.81, 2.14, 2.95, 0.62, 0.72, 0.90 and 0.88, 2.97, 3.85, 0.71, 0.77, 0.93 for males and females, respectively. The rate of exploitation for P. quasigrandis was found to be lower than the Emax which indicates sustainable utilisation of the resource

Present status of exploitation of fish and shellfish resources: Prawns

The Prawn fishery of the west coast of India is reviewed with particular reference to monsoon season and related management problems based on observations at Cochin, Calicut, Mangalore and Bombay. With an estimated average annual production of about 25,000 tonnes for the period 1984-88, the monsoon season contributes only 15% to the total prawn landings of this coast. While shrimp trawling remains almost completely suspended in most of the centres during this period, it is very active at Cochin and Sakthikulangara in Kerala Coast and moderately active in Bombay Coast

Moments of the B Meson Inclusive Semileptonic Decay Rate using Neutrino Reconstruction

We present a measurement of the composition of B meson inclusive semileptonic decays using 9.4 fb^-1 of e^+e^- data taken with the CLEO detector at the Upsilon(4S) resonance. In addition to measuring the charged lepton kinematics, the neutrino four-vector is inferred using the hermiticity of the detector. We perform a maximum likelihood fit over the full three-dimensional differential decay distribution for the fractional contributions from the B -> X_c l nu processes with X_c = D, D*, D**, and nonresonant X_c, and the process B -> X_u l nu. From the fit results we extract the first and second moments of the M_X^2 and q^2 distributions with minimum lepton-energy requirements of 1.0 GeV and 1.5 GeV. We find = 0.456 +- 0.014 +- 0.045 +- 0.109 (GeV/c^2)^2 with a minimum lepton energy of 1.0 GeV and = 0.293 +- 0.012 +- 0.033 +- 0.048 (GeV/c^2)^2 with minimum lepton energy of 1.5 GeV. The uncertainties are from statistics, detector systematic effects, and model dependence, respectively. As a test of the HQET and OPE calculations, the results for the M^X_c moment as a function of the minimum lepton energy requirement are compared to the predictions.Comment: 26 pages postscript, als available through http://w4.lns.cornell.edu/public/CLNS/, Submitted to PRD (back-to-back with following preprint hep-ex/0403053