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

Influence of the Icelandic Low latitude on the frequency of Greenland tip jet events : implications for Irminger Sea convection

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C04020, doi:10.1029/2006JC003807.The occurrence of Greenland tip jet events has been reported as the dominant factor controlling the formation of intermediate water in the Irminger Sea. It has been suggested that the frequency of these events is correlated with the North Atlantic Oscillation. To examine this process in more detail, we separate the North Atlantic Oscillation into Icelandic Low and Azores High components and carry out a regression fit of the frequency of tip jet events between 1961 and 2005. Our findings suggest that the frequency of Greenland tip jet events is highly dependent on the latitude of the Icelandic Low and the 2-year time-lagged February Icelandic Low latitude, with R2 = 0.48. We find that the winds near the southern tip of Greenland are predominately westerly during years when the Iceland Low is located above 63°N latitude. These conditions also correspond to colder air temperatures in the Labrador and Irminger Seas, implying larger oceanic heat losses due to the Greenland tip jet events and hence stronger convective overturning in the Irminger Sea.R. Pickart gratefully acknowledges support by National Science Foundation grant OCE-0450658 for this research

Upgradation of Reading Skill

Reading is one of the greatest phenomena in a nation’s development in various perspectives. Every nation can get free from illiteracy when citizens of the nation become good readers.  Every nation is in need of great leaders. Great leaders can lead the nation. A great leader reads a lot. Reading not only makes a full man, but produces a great leader. That many of our students lack reading skill is a bitter fact and a matter of great concern. The writing skill of our students has deteriorated a lot, because students lack reading skills. Though reading is a passive language-learning skill, the active language-learning skill ‘writing’ can be developed by means of avid reading. Constant readers become good writers. This research paper begins with an introduction to reading skill and its importance, moves with an analysis on the lack of reading skills of students and ends with some strategies and suggestions that could be advocated for the upgradation of reading skills. Keywords: efficient reading skills, passive reading, comprehending ability, contextual meanings, fluency in reading, filled reading

Technical Writing in English - Some Perspectives

The paper begins with an introduction on the importance of English, moves with a brief outline on technical writing in English, highlights some of the notable differences, in terms of written communication, between general English and technical English, advocates ‘experimented’ strategies for augmenting technical writing in English and ends with a conclusion emphasizing the need for developing the technical writing skills of students. Key words: Technical writing, passivity, technical report, tables and charts, technical English, general Englis

Rare occurrence of diamond back squid Thysanoteuthis rhombus (Troschel, 1867) off Chennai coast

A single female specimen of diamond back squid Thysanoteuthis rhombus (Troschel, 1857) locally called 'thalan kadama' was recorded for the first time in the landings of Kasimedu Fishing Harbour on 9.7.2008. The squid was caught in the drift gill net operated off north Chennai at a depth of around 100 m

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

Retained stones in the common bile duct: results of management

Seventeen patients underwent treatment for retained common bile duct stones. In 7 patients the stones were removed via a T-tube tract using steerable catheters while 5 patients underwent ERCP and sphincterotomy and 5 underwent surgical re-exploration. Considering morbidity, mortality, success rate and patients\u27 stay in the hospital, non-operative modalities should be the treatment of choice for retained common bile duct stones