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Miniature High-Sensitivity High-Temperature Fiber Sensor with a Dispersion Compensation Fiber-Based Interferometer
A miniature high-sensitivity, high-temperature fiber sensor with an interferometer based on a bare small-core-diameter dispersion compensation fiber (DCF) is reported. The sensing head is a single-mode-fiber (SMF) DCF configuration formed by a 4 mm long bare DCF with one end connected to the SMF by a fusion splicing technique and the other end cleaved. Due to the large mode index difference and high thermo-optic coefficient induced by two dominative interference modes, a miniature high-temperature fiber sensor with a high sensitivity of 68.6 pm/°C is obtained by monitoring the wavelength shift of the interference spectrum. This type of sensor has the features of small size, high sensitivity, high stability, simple structure, and low cost
First-principles calculations of phase transition, elasticity, and thermodynamic properties for TiZr alloy
tructural transformation, pressure dependent elasticity behaviors, phonon,
and thermodynamic properties of the equiatomic TiZr alloy are investigated by
using first-principles density-functional theory. Our calculated lattice
parameters and equation of state for and phases as well as
the phase transition sequence of
are
consistent well with experiments. Elastic constants of and
phases indicate that they are mechanically stable. For cubic phase,
however, it is mechanically unstable at zero pressure and the critical pressure
for its mechanical stability is predicted to equal to 2.19 GPa. We find that
the moduli, elastic sound velocities, and Debye temperature all increase with
pressure for three phases of TiZr alloy. The relatively large values
illustrate that the TiZr alloy is rather ductile and its ductility is more
predominant than that of element Zr, especially in phase. Elastic wave
velocities and Debye temperature have abrupt increase behaviors upon the
transition at around 10 GPa and exhibit
abrupt decrease feature upon the
transition at higher pressure. Through Mulliken population analysis, we
illustrate that the increase of the \emph{d}-band occupancy will stabilize the
cubic phase. Phonon dispersions for three phases of TiZr alloy are
firstly presented and the phase phonons clearly indicate its
dynamically unstable nature under ambient condition. Thermodynamics of Gibbs
free energy, entropy, and heat capacity are obtained by quasiharmonic
approximation and Debye model.Comment: 9 pages, 10 figure
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