The high-temperature dielectric properties of SiO2/Si3N4 nanocomposites are investigated theoretically and experimentally. Its permittivities and loss tangents at the temperature ranging from room temperature to 1300...The high-temperature dielectric properties of SiO2/Si3N4 nanocomposites are investigated theoretically and experimentally. Its permittivities and loss tangents at the temperature ranging from room temperature to 1300℃ at 9.0 GHz are measured by the resonant cavity method. The SiO2/Si3N4 nanocomposites show complex dielectric behaviour at elevated temperature, and a multi-scale model is proposed to describe the dependence of the dielectric properties in the SiO2/Si3N4 on its compositional variations. Such a theory is needed so that the available property measurements could be extrapolated to other operating frequencies and temperatures.展开更多
Consider the following equations: Where 0 <η< 1,0 <α< 1, and f : [0,1]×[0,∞)→[0,∞), Ii,Li : [0,∞)→R, (i = 1,2,…, k) are continuous functions. We prove the existence of eigenvalues for the prob...Consider the following equations: Where 0 <η< 1,0 <α< 1, and f : [0,1]×[0,∞)→[0,∞), Ii,Li : [0,∞)→R, (i = 1,2,…, k) are continuous functions. We prove the existence of eigenvalues for the problem under a weaker condition, moreover we do not require the monotonicity of the impulsive functions.展开更多
A highly efficient W3 Y-branch filter in a two-dimensional photonic crystal slab with triangular lattice of air holes is designed and fabricated, and its transmission properties are measured. By accurately adjusting t...A highly efficient W3 Y-branch filter in a two-dimensional photonic crystal slab with triangular lattice of air holes is designed and fabricated, and its transmission properties are measured. By accurately adjusting the size of the resonant cavities, the minimum wavelength spacing of 7 nm between two channels is realized. The corresponding resonant wavelengths of the two cavities agree well with the calculated ones. This implies that this kind of fiIter may be promising in integrated wavelength division multiplexing system.展开更多
The quantum tunnelling of magnetization （QTM） in single crystals of the single molecule magnet （Mn1-xCrx）12- Ac （x=0, 0.03, 0.04, 0.05） has been investigated. In comparison with its parent Mnl2-Ac, a greater rat...The quantum tunnelling of magnetization （QTM） in single crystals of the single molecule magnet （Mn1-xCrx）12- Ac （x=0, 0.03, 0.04, 0.05） has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core.展开更多
The high temperature dielectrics of Quartz fiber-reinforced silicon dioxide ceramic (SiO2/SiO2) composites were studied both theoretically and experimentally. A multi-scale theoretical model was developed based on the...The high temperature dielectrics of Quartz fiber-reinforced silicon dioxide ceramic (SiO2/SiO2) composites were studied both theoretically and experimentally. A multi-scale theoretical model was developed based on the theory of dielectrics. It was realized to predict dielectric properties at higher temperature (>1200 °C) by experimental data mining for correlative coefficients in model. The results show that the dielectrics of SiO2/SiO2, which were calculated with the theoretical model, were in agreement with experimental measured value.展开更多
An attempt has been made to construct a novel economy-climate model by combining climate change research with agricultural economy research to evaluate the influence of global climate change on grain yields. The inser...An attempt has been made to construct a novel economy-climate model by combining climate change research with agricultural economy research to evaluate the influence of global climate change on grain yields. The insertion of a climate change factor into the economic C-D (Cobb-Dauglas) production function model yields a novel evaluation model, which connects the climate change factor to the eco-nomic variation factor, and the performance and reasonableness of the novel evaluation model are also preliminarily simulated and verified.展开更多
Carbon tubes were prepared by Ni (or Ti) catalytic pyrolysis of acetylene. The catalytic effect of nanometer nickel powders is related to the reduction temperature in H2 atmosphere. Nanometer nickel powders reduced at...Carbon tubes were prepared by Ni (or Ti) catalytic pyrolysis of acetylene. The catalytic effect of nanometer nickel powders is related to the reduction temperature in H2 atmosphere. Nanometer nickel powders reduced at high temperature have a distinguished catalytic effect, and the yield of the carbon tubes is relatively high; but for the nickel powders reduced at low temperature, the yield of carbon tubes is low, and no tube can be formed. Carbon tubes can only be grown along the edges or on the tips of the Ni (or Ti) sheets reduced at about 770C. But if Ni (or Ti) sheets are etched in acid, at lot of carbon tubes with various forms can be formed on their surface. The structure and morphology of the carbon tubes is studied, and the growth thermodynamics for the straight, curved and helical carbon tubes are systematically investigated for the first time.展开更多
文摘The high-temperature dielectric properties of SiO2/Si3N4 nanocomposites are investigated theoretically and experimentally. Its permittivities and loss tangents at the temperature ranging from room temperature to 1300℃ at 9.0 GHz are measured by the resonant cavity method. The SiO2/Si3N4 nanocomposites show complex dielectric behaviour at elevated temperature, and a multi-scale model is proposed to describe the dependence of the dielectric properties in the SiO2/Si3N4 on its compositional variations. Such a theory is needed so that the available property measurements could be extrapolated to other operating frequencies and temperatures.
基金Supported by the NNSF of China(10371006) Supported by the Youth Teacher Science Research Foundation of Central University of Nationalities(CUN08A)
文摘Consider the following equations: Where 0 <η< 1,0 <α< 1, and f : [0,1]×[0,∞)→[0,∞), Ii,Li : [0,∞)→R, (i = 1,2,…, k) are continuous functions. We prove the existence of eigenvalues for the problem under a weaker condition, moreover we do not require the monotonicity of the impulsive functions.
基金Supported by the National Key Basic Research Programme of China under Grant No 2006CB921702, the National Natural Science Foundation of China under Grant Nos 10404036, 10525419, and 10634080, and the Supercomputing Center, CNIC, CAS.
文摘A highly efficient W3 Y-branch filter in a two-dimensional photonic crystal slab with triangular lattice of air holes is designed and fabricated, and its transmission properties are measured. By accurately adjusting the size of the resonant cavities, the minimum wavelength spacing of 7 nm between two channels is realized. The corresponding resonant wavelengths of the two cavities agree well with the calculated ones. This implies that this kind of fiIter may be promising in integrated wavelength division multiplexing system.
基金Project supported by the National Natural Science Foundation of China （Grant No 10505029）.
文摘The quantum tunnelling of magnetization （QTM） in single crystals of the single molecule magnet （Mn1-xCrx）12- Ac （x=0, 0.03, 0.04, 0.05） has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core.
基金the National Defense 973 (Grant No.513180303) and National Defense Basic Scientific Research (Grant No. A2220061080)the Na-tional Defense Foundation (Grant No. 5142040205BQ0154).
文摘The high temperature dielectrics of Quartz fiber-reinforced silicon dioxide ceramic (SiO2/SiO2) composites were studied both theoretically and experimentally. A multi-scale theoretical model was developed based on the theory of dielectrics. It was realized to predict dielectric properties at higher temperature (>1200 °C) by experimental data mining for correlative coefficients in model. The results show that the dielectrics of SiO2/SiO2, which were calculated with the theoretical model, were in agreement with experimental measured value.
基金Supported by the National Natural Science Foundation of China (Grant No. 40231006)the Major State Basic Research Development Programme (Grant No. 2006CB400503)the Knowledge Innovation Project of China Academy of Sci-ences (Grant No. KZCX3-SW-218)
文摘An attempt has been made to construct a novel economy-climate model by combining climate change research with agricultural economy research to evaluate the influence of global climate change on grain yields. The insertion of a climate change factor into the economic C-D (Cobb-Dauglas) production function model yields a novel evaluation model, which connects the climate change factor to the eco-nomic variation factor, and the performance and reasonableness of the novel evaluation model are also preliminarily simulated and verified.
基金supported by the National Natural Science Foundations of China.
文摘Carbon tubes were prepared by Ni (or Ti) catalytic pyrolysis of acetylene. The catalytic effect of nanometer nickel powders is related to the reduction temperature in H2 atmosphere. Nanometer nickel powders reduced at high temperature have a distinguished catalytic effect, and the yield of the carbon tubes is relatively high; but for the nickel powders reduced at low temperature, the yield of carbon tubes is low, and no tube can be formed. Carbon tubes can only be grown along the edges or on the tips of the Ni (or Ti) sheets reduced at about 770C. But if Ni (or Ti) sheets are etched in acid, at lot of carbon tubes with various forms can be formed on their surface. The structure and morphology of the carbon tubes is studied, and the growth thermodynamics for the straight, curved and helical carbon tubes are systematically investigated for the first time.
