In-Situ Nuclear Magnetic Resonance Investigation of Strain, Temperature, and Strain-Rate Variations of Deformation-Induced Vacancy Concentration in Aluminum

Critical strain to serrated flow in solid solution alloys exhibiting dynamic strain aging (DSA) or Portevin–LeChatelier effect is due to the strain-induced vacancy production. Nuclear magnetic resonance (NMR) techniques can be used to monitor in situ the dynamical behavior of point and line defects in materials during deformation, and these techniques are nondestructive and noninvasive. The new CUT-sequence pulse method allowed an accurate evaluation of the strain-enhanced vacancy diffusion and, thus, the excess vacancy concentration during deformation as a function of strain, strain rate, and temperature. Due to skin effect problems in metals at high frequencies, thin foils of Al were used and experimental results correlated with models based on vacancy production through mechanical work (vs thermal jogs), while in situ annealing of excess vacancies is noted at high temperatures. These correlations made it feasible to obtain explicit dependencies of the strain-induced vacancy concentration on test variables such as the strain, strain rate, and temperature. These studies clearly reveal the power and utility of these NMR techniques in the determination of deformation-induced vacancies in situ in a noninvasive fashion.

MICROANGIOGRAM VIDEO COMPRESSION USING ADAPTIVE PREDICTION

Coronary angiography is an X-ray examination of the heart\u27s arteries. This is an essential technique for diagnosis of heart damages. Image sequences from digital angiography contain areas of high diagnostic interest. Loss of information due to compression for regions of interest (ROI) in angiograms is not tolerable. Since Commercially available technology such as JPEG and MPEG do not satisfy medical requirements due to their severe blockartifacts. In this paper, a new compression algorithm that achieves high compression ratio and excellent reconstruction quality for video rate or sub-video rate angiograms is developed. The proposed algorithm exploits temporal spatial and spectral redundancies in backward adaptive fashion with Extremely low side information. An experimental result shows that the proposed scheme provides significant improvements in compression efficiencies

Some three dimensional elasto-dynamic solutions of layered shells

Three dimensional solutions for natural frequencies and mode shapes of layered composite shells obtained by using the finite layer method, are presented in this paper. Higher order theories for laminated shells are discussed

A Geometric Problem in Simplicial Cones with Applications to Linear Complementarity Problems

We consider the following geometric question: suppose we are given a simplicial cone K in R^n. Can we find a point @) in the interior of K satisfying the property that the orthogonal projection of @) onto the linear hull of every face of K is in the relative interior of that fence? This question plays an important role in determining whether a certain class of linear complementarity problems (LCP 's) can be solved efficiently by a pivotal algorithm. The answer to this question is always in the affirmative if n=2, but not so for n=3. We establish some conditions for the answer to this question to be yes, and relate them to other well known properties of square matrices. e.g., world: simplicial cones, orthogonal projections, faces, linear complementarity problem, LCP, pivotal algorithms, P-matrices, symmetric positive definite matrices, 2-matrices, M-matrices

A POSSIBLE TSUNAMI IN THE LABRADOR SEA RELATED TO THE DRAINAGE OF GLACIAL LAKE AGASSIZ ~8400 YEARS B.P.

For thousands of years, the thick Laurentide Ice Sheet covered a large part of northern North America, damming northward-draining rivers. As this ice retreated, large lakes formed along its margin. Glacial Lake Agassiz was the largest of these ice-marginal lakes, covering an area of >800,000 km2 (more than twice the size of the largest lake in the modern world, the Caspian Sea) before it drained catastrophically into the Labrador Sea. Even before that, Lake Agassiz had periodically released large volumes of water into the ocean via the Great Lakes-St. Lawrence and the Athabasca-Mackenzie River systems. The last and largest of these outbursts released >150,000 km3 through Hudson Bay and Hudson Strait in 6-12 months; the average flux over that period was ~5 Sv (1 Sv = 1×106 m3s-1).When a volume of water this large is discharged into a coastal sea like the Labrador Sea, it may generate a surface flood wave or a tsunami if the water mass is large enough and introduced in a short time. To our knowledge no previous calculations have been made to estimate the potential impact of a flood burst on the generation of solitary waves. Using analogies of tsunamis generated by submarine landslides and ocean earthquakes, the amplitude of a Lake Agassiz generated tsunami is estimated to have been at least 2 m. Directionality considerations, as well as the effect of the Coriolis Force in the Northern Hemisphere, suggest that the resulting tsunami probably traveled 50-100 km along the west coast of the Labrador Sea, south of Hudson Strait where the outburst entered the ocean, before being dissipated. The erosional and depositional affects of historic and prehistoric tsunamis are present in the geological record, and provide guidance in seeking evidence for the Lake Agassiz flood burst and subsequent tsunami. This record may be found along the western coast of the Labrador Sea as well as along the shores of Hudson Strait

Effect of Substituents on Rates of Reactions: Kinetics of Oxidation of Substituted Benzaldehydes by Vanadium(V)

1073-107

India\u27s First Venture Relating to Subsurface Drainage by Horizontal Drains

Landslides in the Nilgiris district in 1978-79 1 caused heavy damages to property and human life. The field studies indicated that in certain spots, the build up of excess hydrostatic pressure, caused by direct and indirect ingress of water into the soil mantle, is the main cause for certain landslides in the region. The paper attempts to give the total case history relating to a pioneering venture of its kind towards the correction of landslides undertaken in India. The case history assumes special significance in as much as the horizontal drains successfully installed for the first time in this country, provided the needed ocular demonstration of the efficacy of horizontal drains to the practicing engineers in India

Control of Surficial Slides by Different Erosion Control Techniques

Many natural and embankment slopes fall due to the erosion of the top surficial soil mantle. Denudation of vegetation from soil slopes combined with the further steepening of slopes due to natural and man-made causes such as cuts result in such a type of failure. Essentially, the corrective measures appropriate for stabilizing these slopes comprise erosion control by establishing vegetation on the slope. The methods of vegetative turfing include asphalt mulch, coir/jute netting, geogrids and stone apron techniques. The paper sets forth the case history giving details of some of the relatively new techniques for erosion control on a hill road in India and evaluates the relative performance and the relative economics of these methods

Measurement of Orbital Decay in the Double Neutron Star Binary PSR B2127+11C

We report the direct measurement of orbital period decay in the double neutron star pulsar system PSR B2127+11C in the globular cluster M15 at the rate of $(-3.95 \pm 0.13) \times 10^{-12}$, consistent with the prediction of general relativity at the $\sim 3$ level. We find the pulsar mass to be $m_p = (1.358 \pm 0.010) M_\odot$ and the companion mass $m_c = (1.354 \pm 0.010) M_\odot$. We also report long-term pulse timing results for the pulsars PSR B2127+11A and PSR B2127+11B, including confirmation of the cluster proper motion.Comment: 12 pages, 4 figures, accepted for publication in ApJ