Dielectric barrier discharge(DBD) attracts lots of attentions for its great application promises,and the rotational temperature is one of its mostly important parameters.In order to measure the rotational temperature ...Dielectric barrier discharge(DBD) attracts lots of attentions for its great application promises,and the rotational temperature is one of its mostly important parameters.In order to measure the rotational temperature of a pulsed DBD in atmospheric air,the temperature is studied by using optical emission spectroscopy(OES).The discharge is excited by a high voltage pulse with 124 ns rise time and 230 ns full width at half maximum(FWHM) at a repetition rate of a few hundred hertz.The rotational temperatures are studied using different voltages,different repetition rates of the pulse power supply,and different gaps between dielectrics: They are in the range from 390 K to 500 K during the whole discharge.When the gap between dielectrics increases,the rotational temperature initially decreases and then increases.The rotational temperature changes complexly when the pulse repetition rate changes.When the voltage increases,the rotational temperature always decreases,which is not expected.These results allow one to predict the rotational temperature at different supply power parameters and electrode configurations,which is useful for the DBD's industrial application.展开更多
Owing to superior coating performance, process cost effectiveness and environmental friendliness, plasma electrolytic oxidation （PEO） attracts increasing attention for the surface treatment of lightweight metals, （...Owing to superior coating performance, process cost effectiveness and environmental friendliness, plasma electrolytic oxidation （PEO） attracts increasing attention for the surface treatment of lightweight metals, （A1, Mg and Ti）, to enhance their physical and mechanical properties. Plasma Electrolytic Oxidation （PEO）, also known as ＂Micro-Arc Oxidation （MAO）＂, is a high voltage plasma-assisted oxidation process uses an aqueous electrolyte to oxidize the metal surfaces to form ceramic oxide coatings which impart a high corrosion and wear resistance. The PEO process of lightweight elements is strongly influenced by such parameters as electrolyte composition and concentration, current or voltage applied and substrate alloy. Generally, these parameters have a direct influence on the discharging behavior： type, size, duration, population density and temperature. The discharges play an essential role in the formation and resulting composition of the 3-layer oxide structure, by influencing phase transformations and crystallization. This, then, affects the physical, mechanical and chemical properties of the coating. A detailed knowledge of the coating mechanisms is extremely important in order to produce a desired coating quality to reach the best performance of the PEO coatings. In PEO process, the ceramic coating grows inwards to the substrate and outwards to the coating surface simultaneously. For the coating growth, there are three simultaneous processes taking place, namely the electrochemical, the plasma chemical reactions and thermal diffusion. Optical emission spectroscopy （OES） was employed for the discharge characterization by following the substrate and electrolyte element present in the plasma discharge during the coating growth, and to determine plasma electron temperatures. The effects of process parameters during the PEO treatment were investigated using OES in the visible and near ultraviolet （NUV） band 285-800 nm. The elements present in the plasma were identified. Stark shifts of spectral lines and line intensity ratios were utilized to determine the plasma electron concentrations and temperatures, respectively.展开更多
In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is propo...In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is proposed for data processing while a blackbody furnace and three optical filters with known spectral transmittance curves were used to make up a true target. The experimental results show that the calculated temperatures are in good agreement with the temperature of the blackbody furnace, and the calculated spectral emissivity curves are in good agreement with the spectral transmittance curves of the filters. The method proposed has been proved to be an effective method for solving the problem of true temperature and emissivity measurement, and it can overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials.展开更多
Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）,...Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）, （111）, and （100） planes, respectively. These structures have been characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, inductively coupled plasma optical emission spectrometry （ICP-OES） and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.展开更多
Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source....Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of Y2O2S:Eu using the light source and the feasibility of the system. The rare earth material Y2O2S:Eu is selected as the material candidate for being the most sensitive.展开更多
Tm^(3+) doped Na_5Lu_9F_(32) single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters ?_t(t=2, 4, 6) were calculated according to the measured absorption s...Tm^(3+) doped Na_5Lu_9F_(32) single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters ?_t(t=2, 4, 6) were calculated according to the measured absorption spectra and physical-chemical properties of the obtained Na_5Lu_9F_(32) single crystal. The stimulated emission cross-section of the ~3F_4→~3H_6 transition(～1.8 μm) is 0.35×10^(-20) cm^2 for Tm^(3+) doped Na_5Lu_9F_(32) single crystal. The emission spectra under the excitation of 790 nm laser diode(LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm^(3+) doped Na_5Lu_9F_(32) single crystal. The research results show that the Tm^(3+) doped Na_5Lu_9F_(32) single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm^(3+)doped Na_5Lu_9F_(32) crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.展开更多
基金Project supported by National Nature Science Foundation of China （11035004）, Double Hundred Talent Foundation of CAEP （2009R0102）, Key Laboratory of Puised Power of CAEP Science and Technology Development Foundation （2008B040237）.
文摘Dielectric barrier discharge(DBD) attracts lots of attentions for its great application promises,and the rotational temperature is one of its mostly important parameters.In order to measure the rotational temperature of a pulsed DBD in atmospheric air,the temperature is studied by using optical emission spectroscopy(OES).The discharge is excited by a high voltage pulse with 124 ns rise time and 230 ns full width at half maximum(FWHM) at a repetition rate of a few hundred hertz.The rotational temperatures are studied using different voltages,different repetition rates of the pulse power supply,and different gaps between dielectrics: They are in the range from 390 K to 500 K during the whole discharge.When the gap between dielectrics increases,the rotational temperature initially decreases and then increases.The rotational temperature changes complexly when the pulse repetition rate changes.When the voltage increases,the rotational temperature always decreases,which is not expected.These results allow one to predict the rotational temperature at different supply power parameters and electrode configurations,which is useful for the DBD's industrial application.
文摘Owing to superior coating performance, process cost effectiveness and environmental friendliness, plasma electrolytic oxidation （PEO） attracts increasing attention for the surface treatment of lightweight metals, （A1, Mg and Ti）, to enhance their physical and mechanical properties. Plasma Electrolytic Oxidation （PEO）, also known as ＂Micro-Arc Oxidation （MAO）＂, is a high voltage plasma-assisted oxidation process uses an aqueous electrolyte to oxidize the metal surfaces to form ceramic oxide coatings which impart a high corrosion and wear resistance. The PEO process of lightweight elements is strongly influenced by such parameters as electrolyte composition and concentration, current or voltage applied and substrate alloy. Generally, these parameters have a direct influence on the discharging behavior： type, size, duration, population density and temperature. The discharges play an essential role in the formation and resulting composition of the 3-layer oxide structure, by influencing phase transformations and crystallization. This, then, affects the physical, mechanical and chemical properties of the coating. A detailed knowledge of the coating mechanisms is extremely important in order to produce a desired coating quality to reach the best performance of the PEO coatings. In PEO process, the ceramic coating grows inwards to the substrate and outwards to the coating surface simultaneously. For the coating growth, there are three simultaneous processes taking place, namely the electrochemical, the plasma chemical reactions and thermal diffusion. Optical emission spectroscopy （OES） was employed for the discharge characterization by following the substrate and electrolyte element present in the plasma discharge during the coating growth, and to determine plasma electron temperatures. The effects of process parameters during the PEO treatment were investigated using OES in the visible and near ultraviolet （NUV） band 285-800 nm. The elements present in the plasma were identified. Stark shifts of spectral lines and line intensity ratios were utilized to determine the plasma electron concentrations and temperatures, respectively.
文摘In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is proposed for data processing while a blackbody furnace and three optical filters with known spectral transmittance curves were used to make up a true target. The experimental results show that the calculated temperatures are in good agreement with the temperature of the blackbody furnace, and the calculated spectral emissivity curves are in good agreement with the spectral transmittance curves of the filters. The method proposed has been proved to be an effective method for solving the problem of true temperature and emissivity measurement, and it can overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials.
基金This work was supported by the National Natural Science Foundation of China （Nos. 91127040 and 21221062）, and the State Key Project of Fundamental Research for Nanoscience and Nanotechnology （No. 2011CB932402）.
文摘Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）, （111）, and （100） planes, respectively. These structures have been characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, inductively coupled plasma optical emission spectrometry （ICP-OES） and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50775198, 60102002, 60974115 and 60977061)the Youth Foundation of Education Bureau of Hebei Province (Grant No.2011225)
文摘Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of Y2O2S:Eu using the light source and the feasibility of the system. The rare earth material Y2O2S:Eu is selected as the material candidate for being the most sensitive.
基金supported by the National Natural Science Foundation of China(Nos.51472125 and 51272109)the Natural Science Foundation of Zhejiang Province(No.LZ17E020001)K.C. Wong Magna Fund in Ningbo University
文摘Tm^(3+) doped Na_5Lu_9F_(32) single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters ?_t(t=2, 4, 6) were calculated according to the measured absorption spectra and physical-chemical properties of the obtained Na_5Lu_9F_(32) single crystal. The stimulated emission cross-section of the ~3F_4→~3H_6 transition(～1.8 μm) is 0.35×10^(-20) cm^2 for Tm^(3+) doped Na_5Lu_9F_(32) single crystal. The emission spectra under the excitation of 790 nm laser diode(LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm^(3+) doped Na_5Lu_9F_(32) single crystal. The research results show that the Tm^(3+) doped Na_5Lu_9F_(32) single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm^(3+)doped Na_5Lu_9F_(32) crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.
