等截面梁有限变形的传递函数解法

本文应用传递函数方法对等截面梁的有限变形进行了分析,对于等截面梁的有限变形问题,该方法从变分方程出发把问题表述为状态空间的形式,然后利用Gauss积分对轴力进行加速迭代求解,不需要进行增量迭代即可取得具有良好计算精度的数值结果,对简单受力的等截面梁情况该解可以看作是所讨论问题的精确解。对于受力比较复杂或者阶梯变截面梁情况,为减少运算量,可以和有限元法类似,采用多个单元进行拼接,从而得到问题的解。数值算例表明,本方法具有半解析、精度高、收敛快等特点。     

计及二阶效应的门座起重机变幅工况动力学分析

对门座起重机的变幅工况进行了计及二阶效应的大范围运动弹性动力分析。使用柔性多体系统动力学方法描述柔性体的变形和运动,结合非线性有限元理论推导了一般运动柔性单元在局部坐标系下的计及二阶效应的动力学方程,进而使用三结点Euler-Bernoulli梁单元的形函数,推导了柔性梁单元的动力学方程。对该方程进行静力凝聚并使用随动坐标法,得到便于系统动力学方程组集的整体坐标系下的两结点梁单元动力学方程。对某型门座起重机臂架系统的变幅工况进行了计及二阶效应的弹性动力分析,结果表明:二阶弹性位移和内力均为相应线性解上的波动,且波动幅值较大,因此对大柔度重载机械应进行考虑二阶效应的弹性动力分析。     

第一原理研究铝锂金属间化合物

运用密度泛函理论系统地研究了二元铝锂金属间化合物Al₃Li、AlLi、Al₂Li₃和Al₄Li₉的结构、形成热、弹性和电子结构.通过计算四种金属间化合物的形成热,证明了金属间化合物中铝和锂之间具有强烈的化学作用. 在富锂金属间化合物中,随着锂的含量的增加,金属间化合物热力学稳定性呈线性减弱. 计算金属间化合物的单晶弹性常数可以得出四种金属间化合物都是机械稳定的. 运用Voigt-Reuss-Hil     

A NOVEL TITANIUM COMPLEX WITH LINKED β-DIKETONATO-INDENYL LIGAND FOR CATALYTIC SYNDIOSPECIFIC POLYMERIZATION OF STYRENE

A novel ligand (3), in which the indenyl group is linked to a β-diketone moiety through a three-carbon bridge, andits titanium complex (4) were synthesized. The titanium complex was employed as a metallocene analog with co-catalystmethylaluminoxane (MAO) in catalytic syndiospecific polymerization of styrene to give highly syndiotactic polystyrene(s-PS, 96%-97%). Polymerization temperature (T_p) strongly influenced the catalytic activity and syndiotacticity of theproduced PS. The activities of catalyst 4 increase from 1.84×10~6 to 3.26×10~6 gPS/molTi·h with the increase of T_p from60℃ to 80℃ and the syndiotacticities of the produced s-PS also increase slightly. Then, both the catalytic activity and thesyndiotacticity of PS decrease at T_p of 90℃.     

Interfacial structure of oxidized inner pores in precursor-derived Si–C–N ceramics

Inner pore channels were commonly found in precursor-derived Si–C–N ceramics. After annealing in air at 1420 °C, their oxidation structures were investigated by analytical TEM. A carbon-rich ring was frequently observed under the silica layer inside the pore channels, which consisted of graphite-like clusters in size of 20–30 nm. Origin of such interfacial structure is due to the excessive free-carbon in the amorphous Si–C–N matrix that had survived the oxidation process. This graphitic interface could further improve the oxidation resistance of the SiO₂ over-layer. This novel interfacial structure was also found by annealing in N₂, reaffirming the effect of composition of Si–C–N matrix.     

温度梯度法生长氟化钙晶体

用温度梯度法成功生长了直径75mm、完整、透明的氟化钙晶体,对晶体进行了TG-DTA测试分析,确定了其熔点为1413.5℃,并测试了晶体从190nm的紫外波段到40000nm的红外波段的透过率,发现从中紫外波段到红外波段氟化钙晶体的透过率已经能满足各种应用的要求,但在远紫外波段和真空紫外波段(246nm以下)氟化钙晶体的透过率需要进一步提高.     

3-aminoacyl-tetrahydrothiazole-2-thione as an active amide for peptide synthesis (I)

3-Aminoacyl-tetrahydrothiazole-2-thione can be used as an active amide for peptide synthesis. A series of peptides have been synthesized with satisfactory yields by this methods.     

合肥光源储存环上八极磁铁的动力学效应分析

 为达到合肥光源二期工程通用模式的设计流强，在储存环上选择垂直方向β函数比较大的位置增加一组八极磁铁。该组八极磁铁对水平方向动力学孔径影响很小，虽然垂直方向动力学孔径明显减小，但仍然大于物理孔径，不会影响束流的注入积累过程。该组八极磁铁产生的垂直方向振荡频率分散可以提供ms量级的Landau阻尼时间，将明显增强抑制垂直方向束流集体不稳定性的能力。该组八极磁铁投入运行后，合肥光源注入积累过程明显改善，注入流强从无八极磁铁时的约100 mA提高到330 mA左右。     

Synthesis of Benzoxepinoquinolinone Derivatives

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红外飞秒激光诱导Ce3+掺杂闪烁晶体的上转换发光研究

本文研究了红外飞秒激光照射下Ce3+ 掺杂的YAP和LSO两种闪烁晶体的上转换发光现象.实验发现在飞秒激光泵浦下,这两种晶体的荧光均来自于Ce3+离子的5d-4f跃迁.荧光强度与泵浦光功率之间的依赖关系揭示了Ce3+:YAP和Ce3+:LSO晶体的上转换过程皆由三光子吸收过程所主导.分析表明,Ce3+:YAP和Ce3+:LSO晶体中的三光子吸收是三光子同时吸收.