On the dynamic tensile strength of Zirconium

Despite its fundamental nature, the process of dynamic tensile failure (spall) is poorly understood. Spall initiation via cracks, voids, etc, before subsequent coalesce, is known to be highly microstructure-dependant. In particular, the availability of slip planes and other methods of plastic deformation controls the onset (or lack thereof) of spall. While studies have been undertaken into the spall response of BCC and FCC materials, less attention has paid to the spall response of highly anisotropic HCP materials. Here the dynamic behaviour of zirconium is investigated via plate-impact experiments, with the aim of building on an ongoing in-house body of work investigating these highly complex materials. In particular, in this paper the effect of impact stress on spall in a commercially sourced Zr rod is considered, with apparent strain-rate softening highlighted

Report on a sperm whale Physeter macrocephalus (Linnaeus) caught at Chennai coast

In Indian Ocean, sperm whales are distributed in substantial numbers near Madagascar, Mahe banks. East and West coast of India and off Sri Lanka. Instances of sperm whales caught / stranded / sighted are reported from Mahabalipuram, Madras, Tranquebar, Nagapattinam, Pondicherry, Pamban, Manauli Island, Krusadai Island, Quilon, Karwar, Mangalore and Kalpen

Stochastic method for in-situ damage analysis

Based on the physics of stochastic processes we present a new approach for structural health monitoring. We show that the new method allows for an in-situ analysis of the elastic features of a mechanical structure even for realistic excitations with correlated noise as it appears in real-world situations. In particular an experimental set-up of undamaged and damaged beam structures was exposed to a noisy excitation under turbulent wind conditions. The method of reconstructing stochastic equations from measured data has been extended to realistic noisy excitations like those given here. In our analysis the deterministic part is separated from the stochastic dynamics of the system and we show that the slope of the deterministic part, which is linked to mechanical features of the material, changes sensitively with increasing damage. The results are more significant than corresponding changes in eigenfrequencies, as commonly used for structural health monitoring.Comment: This paper is accepted by European Physical Journal B on November 2. 2012. 5 pages, 5 figures, 1 tabl

Numerical Modelling of Beach Erosion Along South West Coast of India During South–West Monsoon

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Numerical Modelling Studies on Tsunami Inundation along the Lakshadweep Islands

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Antibacterial, antifungal and insecticidal activities of some selected medicinal plants of polygonaceae

The antibacterial, antifungal and insecticidal activities of the crude extract of Polygonum persicaria, Rumex hastatus, Rumex dentatus, Rumex nepalensis, Polygonum plebejum and Rheum australe have been studied. Six bacterial species were used, of which Citrobacter frundii, Escherichia coli, Enterobacter aerogenes and Staphylococcus aureus were the most susceptible bacterial species to crude extract with MICs 16, 5.0, 25 and 0.156 mg/ml, respectively. Among the tested fungal species Fusarium solani, Aspergillus flavus and Aspergillus niger were more susceptible to crude extracts with MICs 0.75, 2.15, and 1.75 μg/ml, respectively. The crude extracts of R. dentatus and R. nepalensis show significant insecticidal activity against Sitophilus oryzae; P. persicaria and P. plebejum show significant insecticidal activities against Tribolium castaneum, respectively. The above selected plants were shown by in vitro assays to be a potential source for natural antifungal, antibacterial and insecticidal agents.Key words: Polygonum persicaria, Rumex hastatus, Rumex dentatus, Rumex nepalensis, Polygonum plebejum, Rheum australe, antibacterial, antifungal, insecticidal

Comparative study of stripe magnetic domains in epitaxial Ni(111) and Co(0001) films

The evolution of stripe magnetic domain structures observed by magnetic force microscopy on epitaxial Ni(111) and Co(0001) films as a function of film thickness is successfully explained by a periodic one-dimensional model with tilted partial flux closure domains. The model predicts a sizable fraction of the magnetization not being parallel to the film’s normal, which consequentially results in an in-plane magnetization in agreement with the experimentally observed magnetization for these films. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69860/2/JAPIAU-91-10-7550-1.pd

An unusual bumber catch of white prawn, Penaeus indicus from Kovalam bay near Madras

In the history of the fishing village, namely, Kovalam (lat. 12°47'N long. 80°15'E), formerly known as Covelong, situated 35 km south of Madras City, heavy landings of the Indian white prawn, Penaeus indicus caught with gill net have occurred for the firsi time during 16th-20th December, 1984. Recent mark-recapture experiments on P. indicus have also established the fact that a longer migration of tagged white prawns took place from Cochin, (place of release) to Ovari - Manappad fishing villages on the southeast coast (Tinnaveli coast), covering a distance of 330-380 km in 68 to 103 days at a rate of 3.5 to 5.5 km/day. The southward migration of white prawns during the present study was in conjunction with the prevailing southerly current along the coast

Magnetic racetrack memory: from physics to the cusp of applications within a decade

Racetrack memory (RTM) is a novel spintronic memory-storage technology that has the potential to overcome fundamental constraints of existing memory and storage devices. It is unique in that its core differentiating feature is the movement of data, which is composed of magnetic domain walls (DWs), by short current pulses. This enables more data to be stored per unit area compared to any other current technologies. On the one hand, RTM has the potential for mass data storage with unlimited endurance using considerably less energy than today's technologies. On the other hand, RTM promises an ultrafast nonvolatile memory competitive with static random access memory (SRAM) but with a much smaller footprint. During the last decade, the discovery of novel physical mechanisms to operate RTM has led to a major enhancement in the efficiency with which nanoscopic, chiral DWs can be manipulated. New materials and artificially atomically engineered thin-film structures have been found to increase the speed and lower the threshold current with which the data bits can be manipulated. With these recent developments, RTM has attracted the attention of the computer architecture community that has evaluated the use of RTM at various levels in the memory stack. Recent studies advocate RTM as a promising compromise between, on the one hand, power-hungry, volatile memories and, on the other hand, slow, nonvolatile storage. By optimizing the memory subsystem, significant performance improvements can be achieved, enabling a new era of cache, graphical processing units, and high capacity memory devices. In this article, we provide an overview of the major developments of RTM technology from both the physics and computer architecture perspectives over the past decade. We identify the remaining challenges and give an outlook on its future