Aquaranching

Aquaranching is the art of reaping richer crop of shrimp or other aquatic organisms from open waters

Spatiotemporal pattern induced by self and cross-diffusion in a spatial Holling-Tanner model

In this paper, we have made an attempt to provide a unified framework to understand the complex spatiotemporal patterns induced by self and cross diffusion in a spatial Holling-Tanner model forphytoplankton-zooplankton-fish interaction. The effect of critical wave length which can drive the system to instability is investigated. We have examined the criterion between two cross-diffusivity (constant and timevarying)on the stability of the model system and for diffusive instability to occur. Based on these conditions and by performing a series of extensive simulations, we observed the irregular patterns, stationary strips, spots, and strips-spots mixture patterns. Numerical simulation results reveal that the regular strip-spot mixture patterns prevail over the whole domain on increasing the values of self- diffusion coefficients of phytoplankton and zooplankton and the dynamics of the system do not undergo any further changes

Resistivity dependent dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles

High resistivity in nanostructured Pb(Fe0.012Ti0.988)O3 system prepared by using polyvinyl alcohol (PVA) in chemical route is observed. The PVA acts as a surfactant to limit the particle size. The Fe substitution for Ti controls the chemical stoichiometry and reduces the lattice distortion, i.e., c/a ratio, and hence the transition temperature reduces with Fe content. The phase structure, morphology, particle size, dc resistivity, and dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles have been characterized by x-ray diffraction, transmission/scanning electron microscopy, source meter, LCR meter, and vibrating sample magnetometer. The results indicate that the nanosize particles have high resistivity, which improves the dielectric constant at high-frequency region and increases magnetization of the specimens. The observed variable-range-hopping conduction mechanism indicates that Fe doping leads to the occurrence of local defect states in the PbTiO3 lattice. The dispersionless dielectric properties with low loss are observed up to 15 MHz. The dielectric properties are improved than those obtained by the conventional process. The initial permeability values do not exhibit much variation up to ferromagnetic transition temperature after which it falls sharply. The large value of saturation magnetization is observed at room temperature

A Constitutive Modeling and Experimental Effect of Shock Wave on the Microstructural Sub-strengthening of Granular Copper

Micro-sized copper powder (99.95%; O≤0.3) has been shock-processed with explosives of high detonation velocities of the order of 7.5km/s to observe the structural and microstructural sub-strengthening. Axisymmetric shock-consolidation technique has been used to obtain conglomerates of granular Cu. The technique involves the cylindrical compaction system wherein the explosive-charge is in direct proximity with the powder whereas the other uses indirect shock pressure with die-plunger geometry. Numeric simulations have been performed on with Eulerian code dynamics. The simulated results show a good agreement with the experimental observation of detonation parameters like detonation velocity, pressure, particle velocity and shock pressure in the reactive media. A pin contactor method has been utilized to calculate the detonation pressure experimentally. Wide angled x-ray diffraction studies reveal that the crystalline structure (FCC) of the shocked specimen matches with the un-shocked specimen. Field emissive scanning electron microscopic examination of the compacted specimens show a good sub-structural strengthening and complement the theoretical considerations. Laser diffraction based particle size analyzer also points towards the reduced particle size of the shock-processed specimen under high detonation velocities. Micro-hardness tests conducted under variable loads of 0.1kg, 0.05kg and 0.025kg force with diamond indenter optical micrographs indicate a high order of micro-hardness of the order of 159Hv. Nitrogen pycnometry used for the density measurement of the compacts shows that a compacted density of the order of 99.3% theoretical mean density has been achieved