Speciflc Heat-Phonon Spectrum Inversion Problem of High T_c Superconductor

The phonon density of states of YBa2Cu3O6.92 is obtained with the method of Fourier decon-volution and Tikhonov-s regularization technique from the experimental specific heat data. The result is compared with that of neutron inelastic scattering.

Modified simulated annealing evolutionary algorithm for fully distributed fiber Bragg grating temperature sensing

In this paper, we present a simple and fast spectra inversion method to reconstruct the temperature distribution along single fiber Bragg grating （FBC） temperature sensor. This is a fully distributed sensing method based on the simulated annealing evolutionary （SAE） algorithm. Several modifications are made to improve the algorithm efficiency, including choosing the most superior chromosome, setting up the boundary of every gene according to the density of resonance peaks of the reflection spectrum, and dynamically modifying the boundary with the algorithm running. Numerical simulation results show that both the convergence rate and the fluctuation are significantly improved. A high spat-ial temperature resolution of 0.25 mm has been achieved at the time cost of 86 s.

Ultra-wideband terahertz fingerprint enhancement sensing and inversion model supported by single-pixel reconfigurable graphene metasurface

The molecular fingerprint sensing technology based on metasurface has unique attraction in the biomedical field.However,in the terahertz(THz)band,existing metasurface designs based on multi-pixel or angle multiplexing usually require more analyte amount or possess a narrower tuning bandwidth.Here,we propose a novel single-pixel graphene metasurface.Based on the synchronous voltage tuning,this metasurface enables ultra-wideband(1.5 THz)fingerprint enhancement sensing of trace analytes,including chiral optical isomers,with a limit of detection(LoD)≤0.64μg/mm2.The enhancement of the fingerprint signal(17.4 dB)originates from the electromagnetically induced transparency(EIT)effect excited by the metasurface,and the ideal overlap between the light field constrained by single-layer graphene(SLG)and ultra-thin analyte.Meanwhile,due to the unique nonlinear enhancement mechanism in graphene tuning,the absorption envelope distortion is inevitable.To solve this problem,a universal fingerprint spectrum inversion model is developed for the first time,and the restoration of standard fingerprints reaches Rmax 2≥0.99.In addition,the asynchronous voltage tuning of the metasurface provides an opportunity for realizing the dynamic reconfiguration of EIT resonance and the slow light modulation in the broadband range.This work builds a bridge for ultra-wideband THz fingerprint sensing of trace analytes,and has potential applications in active spatial light modulators,slow light devices and dynamic imaging equipments.

Thermodynamic functions of ZrW_2O_8 from its heat capacity

It is interesting to maximize the amount of information we can obtain from one experiment on a single sample. In obtaining all the thermodynamic properties of some materials from their experimental heat capacity data only, we aim to get the tempera- ture-independent energy spectrum. However, all the practical measured energy spectra depend on the temperature of experi- ments. One promising method to obtain the temperature-independent energy spectrum is to solve the so-called specific heat-phonon spectrum inversion （SPI） problem. Here we show, by developing a new practical solution method of SPI, the phonon spectrum of the negative thermal expansion material ZrW208 is obtained. This phonon spectrum is tempera- ture-independent and almost method independent. Hence all the thermodynamic properties of ZrW208, such as thermodynamic potential, entropy, Helmholtz free energy, etc. are obtained by heat capacity only.