In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values...In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values of normal spectral emissivity of the alloys are in between or higher than those of the pure constituent components. Experiments were conducted on the alloy systems Ni-Ti and Au-Ni. Their emissivity as well as electrical resistivity and enthalpy as a function of temperature is presented.展开更多
There exist a considerable variety of factors affecting the spectral emissivity of an object. The authors have designed an improved combined neural network emissivity model, which can identify the continuous spectral ...There exist a considerable variety of factors affecting the spectral emissivity of an object. The authors have designed an improved combined neural network emissivity model, which can identify the continuous spectral emissivity and true temperature of any object only based on the measured brightness temperature data. In order to improve the accuracy of approximate calculations, the local minimum problem in the algorithm must be solved. Therefore, the authors design an optimal algorithm, i.e. a hybrid chaotic optimal algorithm, in which the chaos is used to roughly seek for the parameters involved in the model, and then a second seek for them is performed using the steepest descent. The modelling of emissivity settles the problems in assumptive models in multi-spectral theory.展开更多
We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation...We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation. It is found that the bunching phenomenon is independent of the biexciton binding energy when it varies from 0.59 meV to nearly zero. The photon bunching takes place when the exeiton photon is not spectrally distinguishable from the biexciton photon, and either of them can trigger the %tart＇ in a Hanbury-Brown and Twiss setup. However, if the exciton energy is spectrally distinguishable from the biexciton, the photon statistics will become asymmetric and a cross-bunching lineshape can be obtained. The theoretical calculations based on a model of three-level rate-equation analysis are consistent with the result of g（2）（τ） correlation function measurements.展开更多
The thermal radiation properties of pyrolytic carbon(PyC)protective coatings for monocrystalline silicon furnace prepared by different processes were tested.The changes of normal emissivity of carbon materials caused ...The thermal radiation properties of pyrolytic carbon(PyC)protective coatings for monocrystalline silicon furnace prepared by different processes were tested.The changes of normal emissivity of carbon materials caused by PyC protective coatings were discussed,and the influence of phase structure and surface appearance on the thermal radiation properties was investigated.The results show that the thermal radiation properties of PyC protective coatings with the wave band of 5-25μm are better than C/C substrate,further,normal spectral emissivity of CVD PyC coating remains basically at 0.85-0.90,and the normal total emissivity can reach0.89,which shows high thermal radiation performance.For resin PyC coating and CVD PyC coating,the degree of graphitization are 44.53%and 16.28%respectively,and the R value of Raman spectrum are 0.964and 1.384 respectively.Relatively disorder graphite structure of the latter causes various vibration modes,and the spectral emissivity is better,so the thermal radiation property of CVD PyC coating is excellent.A lot of spherical particles exists on the surface of the CVD PyC coating,and the more interface and spacing of particles reduce the number of particles per unit volume.Therefore,the scattering of thermal radiation is strongly strengthened,and the spectral emissivity is higher.展开更多
In this paper, a low pressure Ar/N2 shock plasma jet with clearly multicycle al- ternating zones produced by a DC cascade arc discharge has been investigated by an emission spectral method combined with Abel inversion...In this paper, a low pressure Ar/N2 shock plasma jet with clearly multicycle al- ternating zones produced by a DC cascade arc discharge has been investigated by an emission spectral method combined with Abel inversion analysis. Plasma emission intensity, electron, vi- brational and rotational temperatures of the shock plasma have been measured in the expansion and compression zones. The results indicate that the ranges of the measured electron temperature, vibrational temperature and rotational temperature are 1.1 eV to 1.6 eV, 0.2 eV to 0.7 eV and 0.19 eV to 0.22 eV, respectively, and it is found for the first time that the vibrational and rota- tional temperatures increase while the electron temperature decreases in the compression zones. The electron temperature departs from the vibrational and the rotational temperatures due to non-equilibrium plasma effects. Electrons and heavy particles could not completely exchange energy via collisions in the shock plasma jet under the low pressure of 620 Pa or so.展开更多
The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed meth...The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed method of evaluation is based on the statistical significance of the analytical response differences during atomic emission spectroscopy of solid specimens taken from one sample before and after heat treatment using the instruments AtomComp 81 and ARL 4460 with a high-voltage spark excitation. For calculations, the ratio of the line intensity of the analyzed element to the line intensity of the main sample component (in our case Ni<sub>2254</sub>) was used. The difference confidence estimation was made by the averages comparison method in a variance analysis. The study results are presented on the effect of material structure on analytical response during atomic emission spectroscopy of solid specimens. It was proved that the samples before and after heat treatment give statistically differing results while analyzed.展开更多
A simplified method for calculating the spectral emission of nonequilibrium air plasmas is developed.In order to obtain the nonequilibrium energy level populations,the nonequilibrium coefficients are introduced into t...A simplified method for calculating the spectral emission of nonequilibrium air plasmas is developed.In order to obtain the nonequilibrium energy level populations,the nonequilibrium coefficients are introduced into the Saha-Boltzmann equation.These nonequilibrium coefficients are calculated by using several significant radiative processes.An approach to the determination of nonequilibrium electronic energy level populations of diatomic molecules is also presented.Based on the method,spectral emission of atoms and molecules in a typical air plasma cell is investigated.The results reveal that there is a significant difference between the nonequilibrium and equilibrium emission.We apply the method to the nonequilibrium AVCO R-156 experiment.Good agreement with the NEQAIR code and the measured data is shown,indicating that the method is reasonable and has good accuracy.展开更多
（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0...（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2 O3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm^3＋ to Ho^3＋ and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to 3 F4→3 H6 transition of Tm^3＋ and 5 I7→5 I8 transition of Ho^3＋, respectively.Better spectral properties were achieved in Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2O3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm^3＋ and 1 mol% Ho^3＋.展开更多
基金This work is financially supported by the "Austrian Science Fund - FWF", Sensengasse 1, 1090 Vienna, under contract No. P15055
文摘In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values of normal spectral emissivity of the alloys are in between or higher than those of the pure constituent components. Experiments were conducted on the alloy systems Ni-Ti and Au-Ni. Their emissivity as well as electrical resistivity and enthalpy as a function of temperature is presented.
文摘There exist a considerable variety of factors affecting the spectral emissivity of an object. The authors have designed an improved combined neural network emissivity model, which can identify the continuous spectral emissivity and true temperature of any object only based on the measured brightness temperature data. In order to improve the accuracy of approximate calculations, the local minimum problem in the algorithm must be solved. Therefore, the authors design an optimal algorithm, i.e. a hybrid chaotic optimal algorithm, in which the chaos is used to roughly seek for the parameters involved in the model, and then a second seek for them is performed using the steepest descent. The modelling of emissivity settles the problems in assumptive models in multi-spectral theory.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922304the National Natural Science Foundation of China under Grant Nos 11474275 and 11464034
文摘We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation. It is found that the bunching phenomenon is independent of the biexciton binding energy when it varies from 0.59 meV to nearly zero. The photon bunching takes place when the exeiton photon is not spectrally distinguishable from the biexciton photon, and either of them can trigger the %tart＇ in a Hanbury-Brown and Twiss setup. However, if the exciton energy is spectrally distinguishable from the biexciton, the photon statistics will become asymmetric and a cross-bunching lineshape can be obtained. The theoretical calculations based on a model of three-level rate-equation analysis are consistent with the result of g（2）（τ） correlation function measurements.
基金Sponsored by the National High Technology Research and Development Program of China(863 Program)(Grant No.2009AA035301)the ChinaPostdoctoral Science Foundation(Grant No.2012M511544)
文摘The thermal radiation properties of pyrolytic carbon(PyC)protective coatings for monocrystalline silicon furnace prepared by different processes were tested.The changes of normal emissivity of carbon materials caused by PyC protective coatings were discussed,and the influence of phase structure and surface appearance on the thermal radiation properties was investigated.The results show that the thermal radiation properties of PyC protective coatings with the wave band of 5-25μm are better than C/C substrate,further,normal spectral emissivity of CVD PyC coating remains basically at 0.85-0.90,and the normal total emissivity can reach0.89,which shows high thermal radiation performance.For resin PyC coating and CVD PyC coating,the degree of graphitization are 44.53%and 16.28%respectively,and the R value of Raman spectrum are 0.964and 1.384 respectively.Relatively disorder graphite structure of the latter causes various vibration modes,and the spectral emissivity is better,so the thermal radiation property of CVD PyC coating is excellent.A lot of spherical particles exists on the surface of the CVD PyC coating,and the more interface and spacing of particles reduce the number of particles per unit volume.Therefore,the scattering of thermal radiation is strongly strengthened,and the spectral emissivity is higher.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB109005,2009GB106004)National Natural Science Foundation of China(Nos.11175035,10875023)the Fundamental Research Funds for the Central Universities of China(DUT 12ZD(G)01,DUT 11ZD(G)06)
文摘In this paper, a low pressure Ar/N2 shock plasma jet with clearly multicycle al- ternating zones produced by a DC cascade arc discharge has been investigated by an emission spectral method combined with Abel inversion analysis. Plasma emission intensity, electron, vi- brational and rotational temperatures of the shock plasma have been measured in the expansion and compression zones. The results indicate that the ranges of the measured electron temperature, vibrational temperature and rotational temperature are 1.1 eV to 1.6 eV, 0.2 eV to 0.7 eV and 0.19 eV to 0.22 eV, respectively, and it is found for the first time that the vibrational and rota- tional temperatures increase while the electron temperature decreases in the compression zones. The electron temperature departs from the vibrational and the rotational temperatures due to non-equilibrium plasma effects. Electrons and heavy particles could not completely exchange energy via collisions in the shock plasma jet under the low pressure of 620 Pa or so.
文摘The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed method of evaluation is based on the statistical significance of the analytical response differences during atomic emission spectroscopy of solid specimens taken from one sample before and after heat treatment using the instruments AtomComp 81 and ARL 4460 with a high-voltage spark excitation. For calculations, the ratio of the line intensity of the analyzed element to the line intensity of the main sample component (in our case Ni<sub>2254</sub>) was used. The difference confidence estimation was made by the averages comparison method in a variance analysis. The study results are presented on the effect of material structure on analytical response during atomic emission spectroscopy of solid specimens. It was proved that the samples before and after heat treatment give statistically differing results while analyzed.
基金supported by the National Numerical Windtunnel project(NNW2019ZT3-B07)the National Natural Science Foundation of China(11674395).
文摘A simplified method for calculating the spectral emission of nonequilibrium air plasmas is developed.In order to obtain the nonequilibrium energy level populations,the nonequilibrium coefficients are introduced into the Saha-Boltzmann equation.These nonequilibrium coefficients are calculated by using several significant radiative processes.An approach to the determination of nonequilibrium electronic energy level populations of diatomic molecules is also presented.Based on the method,spectral emission of atoms and molecules in a typical air plasma cell is investigated.The results reveal that there is a significant difference between the nonequilibrium and equilibrium emission.We apply the method to the nonequilibrium AVCO R-156 experiment.Good agreement with the NEQAIR code and the measured data is shown,indicating that the method is reasonable and has good accuracy.
基金Project supported by Zhejiang Provincial Natural Science Foundation of China(LZ14B010001)
文摘（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2 O3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm^3＋ to Ho^3＋ and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to 3 F4→3 H6 transition of Tm^3＋ and 5 I7→5 I8 transition of Ho^3＋, respectively.Better spectral properties were achieved in Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2O3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm^3＋ and 1 mol% Ho^3＋.
