19 research outputs found
Magnetostriction studies up to megagauss fields using fiber Bragg grating technique
We here report magnetostriction measurements under pulsed megagauss fields
using a high-speed 100 MHz strain monitoring system devised using fiber Bragg
grating (FBG) technique with optical filter method. The optical filter method
is a detection scheme of the strain of FBG, where the changing Bragg wavelength
of the FBG reflection is converted to the intensity of reflected light to
enable the 100 MHz measurement. In order to show the usefulness and reliability
of the method, we report the measurements for solid oxygen, spin-controlled
crystal, and volborthite, a deformed Kagom\'{e} quantum spin lattice, using
static magnetic fields up to 7 T and non-destructive millisecond pulse magnets
up to 50 T. Then, we show the application of the method for the
magnetostriction measurements of CaVO, a two-dimensional
antiferromagnet with spin-halves, and LaCoO, an anomalous spin-crossover
oxide, in the megagauss fields.Comment: 9pages, 6 figures, Conference proceedings for MegaGauss16 at Kashiwa,
Japan in Sept. 201
Digital Sum Problems for the Gray Code Representation of Natural Numbers
We give simple explicit formulas of the power sum and the exponential sum of digital sums of the Gray code representation of natural numbers by use of the distribution function of the singular measure
An Explicit Formula of the Newman-Coquet Exponential Sum
In this paper, we first give an explicit formula of the exponential sum of sum of digits with complex coefficients. As an application of this formula, we obtain a simple expression of Newman-Coquet summation formula related to the number of binary digits in a multiple of three
Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum
The effect of equal-channel angular pressing (ECAP) on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3 of Na2SO4 and 8.46 mol·dm−3 of NaCl (300 ppm Cl−) and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2 revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films