Rocks in the continental crust are long lived and have the potential to record a wide span of tectonic history in rock fabric. Mapping rock fabric in situ at depth requires the application of seismic methods. Below depths of microcrack closure seismic anisotropy presumably reflects the shape and crystallographic preferred orientations influenced by deformation processes. Interpretation of seismic observables relevant for anisotropy requires assumptions on the symmetry and orientation of the bulk elastic tensor. We compare commonly made assumptions against a compilation of 95 bulk elastic tensors from laboratory measurements, including electron backscatter diffraction and ultrasound, on crustal rocks. The majority of samples developed fabric at pressures corresponding to middle to lower crustal condition. Tensor symmetry is a function of mineral modal composition, with mica‐rich samples trending toward hexagonal symmetry, amphibole‐rich samples trending toward an increased orthorhombic symmetry component, and quartz‐feldspar‐rich samples showing a larger component of lower symmetries. Seventy‐seven percent of samples have a best fit hexagonal tensor with slow‐axis symmetry, as opposed to mantle deformation fabric that usually has fast‐axis symmetry. The best fit hexagonal approximation for crustal tensors is not elliptical but deviates systematically from elliptical symmetry with increasing anisotropy, an observation that affects the magnitude and orientation of anisotropy inferred from receiver function and surface wave observations. We present empirical linear relationships between anisotropy and ellipticity for crustal rocks. The maximum out‐of‐plane conversion amplitudes in receiver functions scale linearly with degree of anisotropy for nonelliptical symmetry. The elliptical assumption results in a bias of up to 1.4 times true anisotropy.

The response to post-weld heat treatment of an 18%Ni (250 grade) gas tungsten arc weld metal has been investigated. The post-weld heat treatments are (a) direct aging at 480°C/3 h/air cooling, (b) solutionising at 815°C/1 h/air cooling+aging at 480°C/3 h/air cooling and (c) homogenisation at 1150°C/1 h/air cooling+solutionising at 815°C/1 h/air cooling+aging at 480°C/3 h/air cooling. Metallographic characterisation of fusion zone revealed pronounced segregation of titanium and molybdenum along the interdendritic and intercellular boundaries. This led, during subsequent aging, to austenite reversion at temperatures much lower than in wrought (unwelded) material. Solutionised treatment at 815°C does not remove the segregation. Homogenisation treatment (1150°C/1 h/air cooling) succeeded in making the composition become homogenised. Mechanical properties including tensile, hardness and impact toughness were evaluated. Tensile test results showed that directly aged weldments exhibited lower strength but higher ductility than the other cases; this was attributed to the presence of reverted austenite. Homogenisation at 1150°C/1 h/air cooling+solutionising at 815°C/1 h/air cooling+aging at 480°C/3 h/air cooling resulted in optimum tensile properties. A substantial increase in fusion zone toughness was observed after homogenisation+solutionising+aged condition due to a decrease in the content of austenite content compared to the directly aged condition. The reduction in microsegregation by diffusion of alloying elements from cell boundaries to the cell during homogenisation treatment is responsible for the decrease in austenite content.

The role of post-weld heat treatments on the microstructure and mechanical properties of maraging steel laser welds has been investigated. The post-weld heat treatments are (a) direct ageing at 480 • C/3 h/air cooling, (b) solutionizing at 815 • C/1 h/air cooling + at 480 • C/3 h/air cooling, and (c) homogenization at 1150 • C/1 h/air cooling + solutionizing at 815 • C/1 h/air cooling + ageing at 480 • C/3 h/air cooling. The welded + aged and welded + solutionized + aged microstructure consisting of reverted austenite exhibited low strength and toughness. Homogenization treatment resulted in a microstructure free from reverted austenite and subsequent solutionizing and ageing resulted in improved strength and impact toughness.

The stratigraphy, structure, and tectonics of the Cauvery, Godavari-Krishna, Palar, and Mahanadi Basins located on the east coast of India are considered on the basis of up-to-date surface and subsurface data with particular reference to their evolution during the Mesozoic Era.The sediments exposed in the respective basins are limited to their western and northern borders and represent a relatively smaller stratigraphic interval as compared to the sequence known to be present in the subsurface.Each of these basins is bordered to the west by down-to-the-basin faults. The structural style and recognisable regional trends of the respective basins parallel those of the Eastern Ghats which were largely responsible for their evolution during the Jurassic period. The basin morphology during Late Jurassic comprised horsts and grabens formed due to tensional forces leading to basin subsidence with localised uplifts. The close of the Mesozoic was marked by a regional easterly regression and basinal tilt and an almost complete cessation of horst and graben development and the formation of an essentially monoclinal post-Mesozoic sedimentary cover.A close similarity between the Mesozoic sedimentary basins on the east coast of India and those on the west coast of Australia is marked inasmuch as their tectonic setting, structural style, lithologic suites and faunal and palynological assemblages are concerned. The study broadly indicates that during the Late Jurassic-Early Cretaceous period the basins on the east coast of India were bordered by land masses similar to those postulated to the west of the West Australian basins.

Use of Jatropha Oil Methyl Ester and Its Blends as an Alternative Fuel in Diesel Engine

No abstract

The present study is aimed at filling the gaps in scientific understanding of the burnishing process, and also to aid and arrive at technological solutions for the surface modifications based on burnishing of some of the commonly employed engineering materials. The effects of various burnishing parameters on the surface characteristics, surface microstructure, micro hardness are evaluated, reported and discussed in the case of EN Series steels (EN 8, EN 24 and EN 31), Aluminum alloy (AA6061) and Alpha-beta brass. The burnishing parameters considered for studies principally are burnishing speed, burnishing force, burnishing feed and number of passes. Taguchi technique is employed in the present investigation to identify the most influencing parameters on surface roughness. Effort is also made to identify the optimal burnishing parameters and the factors for scientific basis of such optimization. Finally, a brief attempt is made to construct the Burnishing maps with respect to strength level (in this case, average micro hardness of unburnished material).

IntroductionThe purpose of internal combustion engines is the production of mechanical power from the chemical energy contained in the fuel. In internal combustion engines, as distinct from external combustion engines, this energy is released by burning the fuel inside the engine cylinder. The fuel-air mixture before combustion and the burned products after combustion are the actual working fluids. The work transfers which provide the desired power output occur directly between these working fluids and the mechanical components of the engine. Because of their simplicity, ruggedness and high power-to-weight ratio, the internal combustion engines have found wide applications in transportation and power generation.In spite of many unconventional sources of energy developed, petroleum based fuels remain the primary source of energy in the field of power and propulsion all over the world. The demand for the petroleum products in India is increasing at an alarming rate. For instance the demand for the petroleum products was about 3.5 Million Metric Tons (MMT) in 1950-51, and in 1997-98 it has risen to about 84.3 MMT, in 2004-05 it has reached an alarming value of 111 MMT. At this rate it is believed that the demand may reach a staggering 234 MMT by 2019-20. The approximate petroleum reservoirs in the world are 700 MMT. The domestic production of crude oil is about 33 MMT and the diesel consumption is 40 MMT, the petroleum oils worth Rs.102500 crores were imported (Hey Wood, 2007).Conventional fuels for internal combustion engines are getting dwindled at an alarming rate, primarily due to exponential rise in the population of automobile users world-wide. These fuels are likely to prevail for another 50-75 years unless newer reservoirs are explored. Further, these fuels, upon their combustion release toxic gases into the atmosphere, causing severe environmental pollution and degradation of the quality of air of the atmosphere. Effect of LPG Content on the Performance and Emissions of AbstractIn the present work, LPG, a by-product of petroleum refining process is used to replace conventional diesel fuel, partially, for improved combustion efficiency and clean burning. A conventional diesel engine was operated on the dual-fuel mode, using LPG as the primary fuel and diesel as the pilot fuel. A four-stroke, single-cylinder diesel engine, most widely used in agricultural sector, has been considered for the purpose of experimentation. The engine was operated at a constant speed of 1500 rpm at a low engine load of 20% and a high engine load of 80%. Under both these operating conditions, combustion, performance and emission characteristics of the engine have been evaluated and compared with that of baseline diesel fuel operation. At 20 % engine load the brake thermal efficiency of the engine has found to decrease with an increase in the LPG content. On the other hand at 80% engine load, it has increased with an increase in the LPG content. Same trend has been observed with regard to the mechanical efficiency. The volumetric ...