In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou...In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou Province, Weizhou Island in Guangxi Province and Ningde City in Fujian Province were analyzed in this paper. Six morphometric traits were measured and the degrees of morphological variations among wild Anthocidaris crassispina groups were compared using four multivariate analyses, one-way ANOVA analysis, variation coefficient method, cluster analysis and discriminant analysis. The results of one-way ANOVA analysis showed that there were significant differences in the six morphometric traits between Weizhou Island＇s population and the other five groups. The variation coefficient analysis showed that the difference between the Weizhou Island＇s population and Hailing Is- land＇s population reached the interspecific level. The results of cluster analysis showed that the morphometric characters of Daly Bay＇s population, Egong Bay＇s population and Nan＇ao＇s population were more similar, but the groups from Weizhou Island and Ningde City were the most divergent. The discriminant analysis showed that the identification accuracy of A. crassispina was 47.8%-86%, and the total dis- criminant accuracy was 65.3%. All the analysis results above suggest that certain morphological variation has been generated among A. crassispina groups from differ- ent origins due to geographical isolation and different environmental factors.展开更多
Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical sol...Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.展开更多
In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis an...In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis and path analysis methods.The results showed that there was a difference on meteorological factors in different altitudes, causing different impacts on chemical components of flue-cured tobacco; contents of nicotine and total nitrogen decreased with the rising of altitude, conversely, total sugar and reducing sugar contents increased with the rising trend of altitude, and the differences on the contents of potassium （K） and chlorine（CI）, and the ratio of K to CI in different altitudes were not significant, at the altitude of 1 250-1 450 m, each chemical component indicator was better. The correlation between main meteorological factors and conventional chemical components of tobacco leaves was as follows： contents of reducing sugar and total sugar increased with the increase of rainfall and relative humidity, and decreased with the increase of sunshine duration; nicotine content increased with the increase of accumulated temperature and sunshine duration; total nitrogen （N） content increased with the increase of daily mean temperature and accumulated temperature; sugar-alkali ratio increased with the increase of rainfall. Path analysis showed that the direct effect of sunshine duration on reducing sugar and total sugar of tobacco leaves was faint, but the indirect effect was obvious; meanwhile, the direct and indirect effects of it on nicotine and total N were the greatest.展开更多
[Objective] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field. [Method] In the research, based on a coherent scattering model （Stile）, we proposed a coherent scat...[Objective] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field. [Method] In the research, based on a coherent scattering model （Stile）, we proposed a coherent scattering model exclusive for corn, in which, physical optics （PO） and infinite-length dielectric cylinder were used to calculate single-scattering matrices of corn leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms were also considered and this coherent model was compared with the Michigan Mi- crowave Canopy Scattering （MIMICS） model. The measured data in a corn filed in Gongzhuling in Jilin Province were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV and HH po- larization at L and C bands and made a comparison between the simulation results. [Result] The simulation results at L-band were poor, which indicated that we could not find regularity at early growth stage of vegetation. In addition, comparisons be- tween coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism was small. [Conclusion] In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle, and further analysis on the differences with change of vegetation and soil needed to be made in future.展开更多
The two-dimensional coupled implicit Navier-Stokes equations and standard k-ε viscous models are used to simulate the angle of attack characteristics of an inte- grated hypersonic vehicle with a hark head configurati...The two-dimensional coupled implicit Navier-Stokes equations and standard k-ε viscous models are used to simulate the angle of attack characteristics of an inte- grated hypersonic vehicle with a hark head configuration under three kinds of working conditions： inlet cut-off, engine through-flow, and engine ignition. Influence of each com- ponent on aero-propulsive performance of the vehicle is discussed. It is concluded that the longitudinal static stability of the vehicle is good, and there is enough lift-to-drag ratio to satisfy the flying requirement of the vehicle. At the same time, it is important to change configurations of engine and upper surface of airframe to improve aero-propulsive ~erformance of the vehicle.展开更多
Discusses the symplectic integration of separable Hamiltonian ordinary and partial differential equations (PDE). Results of a von Neumann analysis; Spectra of linearized Hamiltonian PDEs.
基金Supported by National Key Technology Research and Development Program(2012BAD18B02,2012BAD18B01-2)Special Scientific Research Fund of Marine Public Welfare Profession of China(201205021-3)National Nonprofit Institute Research Grant of CATAS-TCGRI(2015TS05)~~
文摘In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou Province, Weizhou Island in Guangxi Province and Ningde City in Fujian Province were analyzed in this paper. Six morphometric traits were measured and the degrees of morphological variations among wild Anthocidaris crassispina groups were compared using four multivariate analyses, one-way ANOVA analysis, variation coefficient method, cluster analysis and discriminant analysis. The results of one-way ANOVA analysis showed that there were significant differences in the six morphometric traits between Weizhou Island＇s population and the other five groups. The variation coefficient analysis showed that the difference between the Weizhou Island＇s population and Hailing Is- land＇s population reached the interspecific level. The results of cluster analysis showed that the morphometric characters of Daly Bay＇s population, Egong Bay＇s population and Nan＇ao＇s population were more similar, but the groups from Weizhou Island and Ningde City were the most divergent. The discriminant analysis showed that the identification accuracy of A. crassispina was 47.8%-86%, and the total dis- criminant accuracy was 65.3%. All the analysis results above suggest that certain morphological variation has been generated among A. crassispina groups from differ- ent origins due to geographical isolation and different environmental factors.
基金supported by the National Natural Science Foundation of China (50976003,51136005)Doctoral Fund of Ministry of Education of China (20100001120003)
文摘Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.
文摘In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis and path analysis methods.The results showed that there was a difference on meteorological factors in different altitudes, causing different impacts on chemical components of flue-cured tobacco; contents of nicotine and total nitrogen decreased with the rising of altitude, conversely, total sugar and reducing sugar contents increased with the rising trend of altitude, and the differences on the contents of potassium （K） and chlorine（CI）, and the ratio of K to CI in different altitudes were not significant, at the altitude of 1 250-1 450 m, each chemical component indicator was better. The correlation between main meteorological factors and conventional chemical components of tobacco leaves was as follows： contents of reducing sugar and total sugar increased with the increase of rainfall and relative humidity, and decreased with the increase of sunshine duration; nicotine content increased with the increase of accumulated temperature and sunshine duration; total nitrogen （N） content increased with the increase of daily mean temperature and accumulated temperature; sugar-alkali ratio increased with the increase of rainfall. Path analysis showed that the direct effect of sunshine duration on reducing sugar and total sugar of tobacco leaves was faint, but the indirect effect was obvious; meanwhile, the direct and indirect effects of it on nicotine and total N were the greatest.
基金Supported by Hunan Provincial Natural Science Foundation(10JJ4027)Opening Fund of State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing(10R01)~~
文摘[Objective] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field. [Method] In the research, based on a coherent scattering model （Stile）, we proposed a coherent scattering model exclusive for corn, in which, physical optics （PO） and infinite-length dielectric cylinder were used to calculate single-scattering matrices of corn leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms were also considered and this coherent model was compared with the Michigan Mi- crowave Canopy Scattering （MIMICS） model. The measured data in a corn filed in Gongzhuling in Jilin Province were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV and HH po- larization at L and C bands and made a comparison between the simulation results. [Result] The simulation results at L-band were poor, which indicated that we could not find regularity at early growth stage of vegetation. In addition, comparisons be- tween coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism was small. [Conclusion] In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle, and further analysis on the differences with change of vegetation and soil needed to be made in future.
基金supported by the Excellent Graduate Student Innovative Project of National University of Defense Technology (No. B070101)Hunan Provincial Innovation Foundation for Postgraduate(No. 3206)
文摘The two-dimensional coupled implicit Navier-Stokes equations and standard k-ε viscous models are used to simulate the angle of attack characteristics of an inte- grated hypersonic vehicle with a hark head configuration under three kinds of working conditions： inlet cut-off, engine through-flow, and engine ignition. Influence of each com- ponent on aero-propulsive performance of the vehicle is discussed. It is concluded that the longitudinal static stability of the vehicle is good, and there is enough lift-to-drag ratio to satisfy the flying requirement of the vehicle. At the same time, it is important to change configurations of engine and upper surface of airframe to improve aero-propulsive ~erformance of the vehicle.
文摘Discusses the symplectic integration of separable Hamiltonian ordinary and partial differential equations (PDE). Results of a von Neumann analysis; Spectra of linearized Hamiltonian PDEs.
