194 research outputs found
Granular Trenches and Stone Columns as Ground Improvement Techniques — Case Histories of Field Applications
Vast areas of Deposits of Soft clays and loose sands is a common occurrence generally in all the countries particularly in the Coastal towns of the State of Andhra Pradesh, India. The utility of these deposits for founding structures becomes vital in view of the enormous land cost and their existence in developed areas. The structures resting on these deposits will be subjected to many problems as these deposits possess very low insitu strength. Appropriate ground improvement technique, supported by quality assurance tests after implementation of technique in the field will be a better solution in problematic soils. The paper aims in presenting the field applications of Granular Trenches and Stone Columns for the construction of Bus stations at three different regions
Absence of Magnetism in Hcp Iron-Nickel at 11 K
Synchrotron Mössbauer spectroscopy (SMS) was performed on an hcp-phase alloy of composition Fe92Ni8 at a pressure of 21 GPa and a temperature of 11 K. Density functional theoretical calculations predict antiferromagnetism in both hcp Fe and hcp Fe-Ni. For hcp Fe, these calculations predict no hyperfine magnetic field, consistent with previous experiments. For hcp Fe-Ni, however, substantial hyperfine magnetic fields are predicted, but these were not observed in the SMS spectra. Two possible explanations are suggested. First, small but significant errors in the generalized gradient approximation density functional may lead to an erroneous prediction of magnetic order or of erroneous hyperfine magnetic fields in antiferromagnetic hcp Fe-Ni. Alternately, quantum fluctuations with periods much shorter than the lifetime of the nuclear excited state would prohibit the detection of moments by SMS
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High-Pressure X-ray Diffraction and Raman Spectroscopy of Ice VIII
In situ high-pressure/low-temperature synchrotron x-ray diffraction and optical Raman spectroscopy were used to examine the structural properties, equation of state, and vibrational dynamics of ice VIII. The x-ray measurements show that the pressure-volume relations remain smooth up to 23 GPa at 80 K. Although there is no evidence for structural changes to at least 14 GPa, the unit-cell axial ratio c/a undergoes changes at 10-14 GPa. Raman measurements carried out at 80 K show that the nu(Tz)A(1g)+nu Tx,yEg lattice modes for the Raman spectra of ice VIII in the lower-frequency regions (50-800 cm(-1)) disappear at around 10 GPa, and then a new peak of similar to 150 cm(-1) appears at 14 GPa. The combined data provide evidence for a transition beginning near 10 GPa. The results are consistent with recent synchrotron far-IR measurements and theoretical calculations. The decompressed phase recovered at ambient pressure transforms to low-density amorphous ice when heated to similar to 125 K.Engineering and Applied Science
Lithium Subhydrides Under Pressure and their Superatom-Like Building Blocks
Evolutionary structure searches are used to predict a new class of compounds
in the lithium--rich region of the lithium/hydrogen phase diagram under
pressure. First principles computations show that LimH, 4<m<9, are stabilized
with respect to LiH and Li between 50-100 GPa. The building block of all of the
lithium subhydrides is an Li8H cluster, which can be thought of as a
superalkali. The geometries and electronic structures of these phases is
analogous to that of the well-known alkali metal suboxides.Comment: ChemPlusChem, accepte
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