65,902 research outputs found
High Spectral Purity, Narrow Linewidth Laser Transmitter for Dial Measurements
A laser transmission with very high degree of spectral purity was described. Amplified Spontaneous Emission (ASE) dependence on the oscillator energy and the detuning away from the gain curve center are demonstrated. The effects of both finite laser linewidth and spectral purity on humidity measurements are experimentally demonstrated
Development of Low Temperature and High Magnetic Field X-Ray Diffraction Facility
The current progress of materials science regarding multifunctional materials
(MFM) has put forward the challenges to understand the microscopic origin of
their properties. Most of such MFMs have magneto-elastic correlations. To
investigate the underlying mechanism, it is therefore essential to investigate
the structural properties in the presence of magnetic field. Keeping this in
view low temperature and high magnetic field (LTHM) powder x-ray diffraction
(XRD), a unique state-of-art facility in India has been developed at CSR
Indore. This setup works on symmetric Bragg Brentano geometry using a parallel
incident x-ray beam from a rotating anode source working at 17 kW. Using this
one can do structural studies at non-ambient conditions i.e. at low-
temperatures (2-300 K) and high magnetic field (+8 to -8 T). The available
scattering angle ranges from 5{\deg} to 115{\deg} 2{\theta} with a resolution
better than 0.1{\deg}. The proper functioning of the setup has been checked
using Si sample. The effect of magnetic field on the structural properties has
been demonstrated on Pr0.5Sr0.5MnO3 sample. Clear effect of field induced phase
transition has been observed. Moreover, the effect of zero field cooled and
field cooled conditions is also observed.Comment: DAE-SSPS-2014, AIP Conf.Proc. (2015) (accepted), 4 Pages, 2 figure
Reviewing the Carbonation Resistance of Concrete
The paper reviews the studies on one of the important durability properties of concrete i.e. Carbonation. One of the main causes of deterioration of concrete is carbonation, which occurs when carbon dioxide (CO2) penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Carbonation is a major cause of degradation of concrete structures leading to expensive maintenance and conservation operations. Herein, the importance, process and effect of various parameters such as water/cement ratio, water/binder ratio, curing conditions, concrete cover, super plasticizers, type of aggregates, grade of concrete, porosity, contaminants, compaction, gas permeability, supplementary cementitious materials (SCMs)/ admixtures on the carbonation of concrete has been reviewed. Various methods for estimating the carbonation depth are also reported briefl
Further Series Studies of the Spin-1/2 Heisenberg Antiferromagnet at T=0: Magnon Dispersion and Structure Factors
We have extended our previous series studies of quantum antiferromagnets at
zero temperature by computing the one-magnon dispersion curves and various
structure factors for the linear chain, square and simple cubic lattices. Many
of these results are new; others are a substantial extension of previous work.
These results are directly comparable with neutron scattering experiments and
we make such comparisons where possible.Comment: 15 pages, 12 figures, revised versio
Evaluating the Carbonation Resistance of Self Compacting Concrete made with Recycled Concrete Aggregates
The paper presents the results of an investigation conducted to examine carbonation resistance of Self Compacting Concrete (SCC) made with coarse Recycled Concrete Aggregates (RCA). In total, five SCC mixes were prepared by systematically replacing coarse Natural Aggregates (NA) by RCA at 0, 25, 50, 75 and 100%. In order to measure the carbonation resistance of SCC made with RCA, accelerated carbonation tests were performed for 4 and 12 weeks of exposure to carbon dioxide. The carbonation resistance has been evaluated after curing periods of 28 and 90 days. In addition to this, the compressive strength of all the mixes was also obtained after 7, 28 and 90 days of curing and ultra-sonic pulse velocity tests (UPV) were also conducted. The results indicate that with the increase in the content of RCA as replacement of NA, decrease in the carbonation resistance, compressive strength and UPV was observed for all SCC mixes. It has been observed that the SCC mixes containing low percentages of RCA (i.e. 25%) as replacement of NA do not impart detrimental behaviour in the overall performance but higher replacement levels (50%) have been found to deteriorate the performance in terms of carbonation resistance, compressive strength and UPV
Reviewing the Carbonation Resistance of Concrete
The paper reviews the studies on one of the important durability properties of concrete i.e. Carbonation. One of the main causes of deterioration of concrete is carbonation, which occurs when carbon dioxide (CO2) penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Carbonation is a major cause of degradation of concrete structures leading to expensive maintenance and conservation operations. Herein, the importance, process and effect of various parameters such as water/cement ratio, water/binder ratio, curing conditions, concrete cover, super plasticizers, type of aggregates, grade of concrete, porosity, contaminants, compaction, gas permeability, supplementary cementitious materials (SCMs)/ admixtures on the carbonation of concrete has been reviewed. Various methods for estimating the carbonation depth are also reported briefl
Quantum mechanics without spacetime II : noncommutative geometry and the free point particle
In a recent paper we have suggested that a formulation of quantum mechanics
should exist, which does not require the concept of time, and that the
appropriate mathematical language for such a formulation is noncommutative
differential geometry. In the present paper we discuss this formulation for the
free point particle, by introducing a commutation relation for a set of
noncommuting coordinates. The sought for background independent quantum
mechanics is derived from this commutation relation for the coordinates. We
propose that the basic equations are invariant under automorphisms which map
one set of coordinates to another- this is a natural generalization of
diffeomorphism invariance when one makes a transition to noncommutative
geometry. The background independent description becomes equivalent to standard
quantum mechanics if a spacetime manifold exists, because of the proposed
automorphism invariance. The suggested basic equations also give a quantum
gravitational description of the free particle.Comment: 8 page
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