非局部非对称弹性理论混合边值问题的提法

从完全的虚功和虚功率原理以及广义Ｐｉｏｌａ定理出发一并推导出非局部非对称弹性理论的运动方程、所有边界条件和全能量方程。把这时给出的边界条件和高键,戴天民的相应结果加在一超即可表述非局部非对称线性弹性理论的混合边值问题。     

Rhodium-catalyzed asymmetric hydrogenation of olefins with PhthalaPhos, a new class of chiral supramolecular ligands

A library of 19 binol-derived chiral monophosphites that contain a phthalic acid diamide group (PhthalaPhos) has been designed and synthesized in four steps. These new ligands were screened in the rhodium-catalyzed enantioselective hydrogenation of prochiral dehydroamino esters and enamides. Several members of the library showed excellent enantioselectivity with methyl 2-acetamido acrylate (6 ligands gave >97% ee), methyl (Z)-2-acetamido cinnamate (6 ligands gave >94% ee), and N-(1-phenylvinyl)acetamide (9 ligands gave >95% ee), whilst only a few representatives afforded high enantioselectivities for challenging and industrially relevant substrates N-(3,4-dihydronaphthalen-1-yl)-acetamide (96% ee in one case) and methyl (E)-2-(acetamidomethyl)-3-phenylacrylate (99% ee in one case). In most cases, the new ligands were more active and more stereoselective than their structurally related monodentate phosphites (which are devoid of functional groups that are capable of hydrogen-bonding interactions). Control experiments and kinetic studies were carried out that allowed us to demonstrate that hydrogen-bonding interactions involving the diamide group of the PhthalaPhos ligands strongly contribute to their outstanding catalytic properties. Computational studies carried out on a rhodium precatalyst and on a conceivable intermediate in the hydrogenation catalytic cycle shed some light on the role played by hydrogen bonding, which is likely to act in a substrate-orientation effect.     

铝合金矩形薄壁梁压溃实验及理论与数值分析

平均压溃力反映乘用车纵梁在碰撞过程中吸收能量的能力,而矩形薄壁梁具有较高的溃缩吸能比,被广泛应用于纵梁的结构设计。本文通过轴向压溃实验研究了矩形薄壁梁的压溃性能,采用非对称超折叠单元理论对矩形薄壁梁平均压溃力进行公式推导,之后对矩形薄壁梁进行有限元压溃数值模拟,得到矩形薄壁梁平均压溃力的实验值、理论值及模拟值。通过对结果的比较可以得出,平均压溃力的理论结果和数值计算结果均与实验测得的结果吻合,这为矩形薄壁梁前期的结构设计提供了有效的理论指导。