The global gravitational model can be expressed as a series of spherical harmonic coefficients computed up to a certain degree and order.The main ordering characteristic can depend on the degree,order,or type of coeff...The global gravitational model can be expressed as a series of spherical harmonic coefficients computed up to a certain degree and order.The main ordering characteristic can depend on the degree,order,or type of coefficient.When determining the spherical harmonic coefficients using the least squares method,it is essential to analyze the ordering pattern of these coefficients and their positions(e.g.,indices)in the vector or matrix.A systematic analysis on the type of coefficient arrangement is presented in this paper.Moreover,the index algorithm for each coefficient ordering pattern is provided.Additionally,the structure of the normal equation matrix with different coefficient arrangement patterns is analyzed.Based on the analysis and the algorithm presented in this paper:(1)we can calculate the index of each coefficient in the vector or matrix of the normal equation;(2)we can change the structure of the normal equation matrix of the Earth’s gravity field from one type of coefficient arrangement to another.Furthermore,(3)we can directly combine different structures of the normal equation matrix,calculated from different types of gravity satellite missions,to form combined normal equations.This approach is beneficial for the determination of Earth’s gravitational model using multi-type observation data.展开更多
To avoid the negative effects of disturbances on satellites,the characteristics of micro-vibration on flywheels are studied.Considering rotor imbalance,bearing imperfections and structural elasticity,the extended mode...To avoid the negative effects of disturbances on satellites,the characteristics of micro-vibration on flywheels are studied.Considering rotor imbalance,bearing imperfections and structural elasticity,the extended model of micro-vibration is established.In the feature extraction of micro-vibration,singular value decomposition combined with the improved Akaike Information Criterion(AIC-SVD)is applied to denoise.More robust and self-adaptable than the peak threshold denoising,AIC-SVD can effectively remove the noise components.Subsequently,the effective harmonic coefficients are extracted by the binning algorithm.The results show that the harmonic coefficients have great identification in frequency domain.Except for the fundamental frequency caused by rotor imbalance,the harmonics are also caused by the coupling of imperfections on bearing components.展开更多
The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum...The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum size,confinement potential depth and the external environment.The numerical simulation results indicate that the THG coefficient can reach the order of 10~(-12)m~2V~(-2),which strongly relies on the tunable factor,with its resonant peak experiencing a redshift or blueshift.Interestingly,the effect of temperature on the THG coefficient in terms of peak location and size is consistent with the quantum dot radius but contrasts with the hydrostatic pressure.Thus,it is crucial to focus on the influence of internal and external parameters on nonlinear optical effects,and to implement the theory in practical experiments and the manufacture of optoelectronic devices.展开更多
Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films contain...Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a vip exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.展开更多
As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability ...As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability indicator, harmonizing coefficient, grey corretation coefficient and production dominance. This study focused on rational hierarchical structure, the limiting factors and optimal strategies of the model development based on model structure, resource conditions and external market demands. Results showed that rational mechanism of the rubber-tea-chicken ecosystem model mainly included technological contributions, leverage function of dominance component （livestock husbandry）, stability of the model structure and harmony of its components, the model dominant product＇s market demand and government＇s supporting policies. The contributions of fund, technology, information and talent resources played an important role in improving sustainability and productivity of the agro-forestry model.展开更多
基金supported by The National Natural Science Foundation of China(42374004).
文摘The global gravitational model can be expressed as a series of spherical harmonic coefficients computed up to a certain degree and order.The main ordering characteristic can depend on the degree,order,or type of coefficient.When determining the spherical harmonic coefficients using the least squares method,it is essential to analyze the ordering pattern of these coefficients and their positions(e.g.,indices)in the vector or matrix.A systematic analysis on the type of coefficient arrangement is presented in this paper.Moreover,the index algorithm for each coefficient ordering pattern is provided.Additionally,the structure of the normal equation matrix with different coefficient arrangement patterns is analyzed.Based on the analysis and the algorithm presented in this paper:(1)we can calculate the index of each coefficient in the vector or matrix of the normal equation;(2)we can change the structure of the normal equation matrix of the Earth’s gravity field from one type of coefficient arrangement to another.Furthermore,(3)we can directly combine different structures of the normal equation matrix,calculated from different types of gravity satellite missions,to form combined normal equations.This approach is beneficial for the determination of Earth’s gravitational model using multi-type observation data.
基金National Natural Science Foundation of China(No.U1831123)Fundamental Research Funds for the Central Universities,China(No.2232017A3-04)。
文摘To avoid the negative effects of disturbances on satellites,the characteristics of micro-vibration on flywheels are studied.Considering rotor imbalance,bearing imperfections and structural elasticity,the extended model of micro-vibration is established.In the feature extraction of micro-vibration,singular value decomposition combined with the improved Akaike Information Criterion(AIC-SVD)is applied to denoise.More robust and self-adaptable than the peak threshold denoising,AIC-SVD can effectively remove the noise components.Subsequently,the effective harmonic coefficients are extracted by the binning algorithm.The results show that the harmonic coefficients have great identification in frequency domain.Except for the fundamental frequency caused by rotor imbalance,the harmonics are also caused by the coupling of imperfections on bearing components.
基金National Natural Science Foundation of China(Grant Nos.11674312,52174161,51702003,12174161 and 61775087)Anhui University of Science and Technology(Grant No.2023CX2141)。
文摘The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum size,confinement potential depth and the external environment.The numerical simulation results indicate that the THG coefficient can reach the order of 10~(-12)m~2V~(-2),which strongly relies on the tunable factor,with its resonant peak experiencing a redshift or blueshift.Interestingly,the effect of temperature on the THG coefficient in terms of peak location and size is consistent with the quantum dot radius but contrasts with the hydrostatic pressure.Thus,it is crucial to focus on the influence of internal and external parameters on nonlinear optical effects,and to implement the theory in practical experiments and the manufacture of optoelectronic devices.
基金supported by a Start-up Grant from Southeast University to Dr Chao-Zhi Zhang and the Science Foundation of Jiangsu Province of China(No.BK2004085).
文摘Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a vip exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.
基金funded by National Natural Science Foundation of China(Grant No.40971227)International science & Technology Cooperation Program of China (Grant No.2010DFA21880)China Postdoctoral Science Foundation
文摘As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability indicator, harmonizing coefficient, grey corretation coefficient and production dominance. This study focused on rational hierarchical structure, the limiting factors and optimal strategies of the model development based on model structure, resource conditions and external market demands. Results showed that rational mechanism of the rubber-tea-chicken ecosystem model mainly included technological contributions, leverage function of dominance component （livestock husbandry）, stability of the model structure and harmony of its components, the model dominant product＇s market demand and government＇s supporting policies. The contributions of fund, technology, information and talent resources played an important role in improving sustainability and productivity of the agro-forestry model.
