Analysis on Morphological Variations among Six Wild Groups of Anthocidaris crassispina from South China Sea

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.

Asymptotic analysis of outwardly propagating spherical flames

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.

Research on the Correlation between Meteorological Factors and Flue-cured Tobacco Chemical Components in Different Altitudes of Lincang Region

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.

陶瓷基复合材料粘接构件超声特征研究方法

新型航天器机体外层陶瓷基复合材料隔热构件在粘贴过程中会产生缺陷,不利于航天器的飞行安全。针对一种陶瓷基多孔复合材料粘接结构构件,利用自主研制的超声C扫描自动检测系统,研究构件粘接层缺陷的超声检测特征。考虑材料多孔性和各向异性会导致超声数据多噪音,采用自适应小波阈值算法对超声信号进行去噪,从而提高透射声波的信噪比。在此基础上,提出采用Hilbert-Huang变换(HHT)和伪Wigner-Ville分布(PWVD)相结合的方法对透射声波进行时频分析,得到时间、频率和幅值的三维分布,从而获得超声透射波最大幅值和对应的时间和频率。通过对比缺陷处与非缺陷处超声透射信号的时频域分布,揭示了该类新型陶瓷基复合材料粘接缺陷对超声信号的影响特点。

Comparison between Microwave Coherent and Incoherent Scattering Models in Corn Field

[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.

厚板齿形零件精冲成形数值模拟与缺陷分析

运用有限元分析软件对厚板齿形零件的精冲过程进行了数值模拟,对比分析了齿顶、齿根部位主要变形区静水应力及应变的分布情况。结果显示,齿顶处静水压应力小于齿根处;齿顶应变区的宽度大于齿根应变区的宽度,齿顶剪切区变形程度大,硬化程度严重。齿根、齿顶处的应变分布与精冲试验所得零件的硬化程度相吻合。探究了齿顶处形成大塌角和易产生撕裂的原因。研究结果为厚板齿形零件的精冲工艺提供了理论指导。

饼形锻件的质量控制

对圆饼形锻件产生密集形缺陷的原因进行了分析，指出其探伤合格率低的原因和其成形过程密切相关，镦粉工步有使锻件缺陷叠加的倾向；提出提高饼形件合格率必须从炼钢人手，减少有害元素含量，同时要改变锻造变形工步，采用Ｖ型板以改变金属纤维流线。

VON NEUMANN STABILITY ANALYSIS OF SYMPLECTIC INTEGRATORS APPLIED TO HAMILTONIAN PDEs

Discusses the symplectic integration of separable Hamiltonian ordinary and partial differential equations (PDE). Results of a von Neumann analysis; Spectra of linearized Hamiltonian PDEs.