Synthesis of Unsymmetrical 1,3‐Diynes via Pd/Cu‐Catalyzed Cross‐Coupling of Terminal Alkynes at Room Temperature

A facile and practical synthetic route of unsymmetrical 1,3‐diynes via the PdCl/CuI catalyzed oxidative coupling of two different terminal alkynes has been developed by using 3‐(diphenylphosphino)propanoic acid as a ligand in the presence of oxygen. This system is suitable for not only aromatic alkynes but also heteroaromatic and aliphatic alkynes which were transformed into the corresponding unsymmetrical 1,3‐diynes in moderate to good yields at room temperature. Moreover, the unsymmetrical 1,3‐diynes were also obtained on a multi‐gram scale. Mechanistic studies suggest that oxygen plays a key role in the catalytic cycles.     

具有攻击角约束的非奇异终端滑模导引律设计

为了满足导弹拦截高速大机动目标时高精度制导的需求,首先对二维平面内的弹目相对运动方程进行状态扩张,对于影响制导性能的目标总扰动采用了扩张状态观测器的方法进行动态补偿。然后在非奇异终端滑模面的基础上选取了两种滑模趋近律,设计了两种具有攻击角约束的非奇异终端滑模导引律。最后数值仿真结果表明,在观测器对扩张系统状态进行实时有效估计的前提下,针对不同的期望视线角和目标机动方式,所设计的两种导引律在满足期望的性能要求的同时,可实现导弹对目标的高精度快速打击。     

对四类泻流问题的深入研究

对热学中的4类泻流问题进行了详细的计算,并对结果进行了分析讨论.恒温的泻流问题有解析的解,而绝热泻流问题往往受限于数学知识只能得到数值的结果;同时本文也对泻流的近平衡态条件进行了大致的分析.这些将有助于广大师生对于泻流问题的全面认识.     

Liner ship fleet deployment with week-dependent container shipment demand

This paper addresses a practical liner ship fleet deployment problem with week-dependent container shipment demand and transit time constraint, namely, maximum allowable transit time in container routing between a pair of ports. It first uses the space–time network approach to generate practical container routes subject to the transit time constraints. This paper proceeds to formulate the fleet deployment problem based on the practical container routes generated. In view of the intractability of the formulation, two relaxation models providing lower bounds are built: one requires known container shipment demand at the fleet deployment stage, and the other assumes constant container shipment demand over the planning horizon. An efficient global optimization algorithm is subsequently proposed. Extensive numerical experiments on the shipping data of a global liner shipping company demonstrate the applicability of the proposed model and algorithm.     

集装箱翻箱问题的蚁群算法改进

翻箱问题属于NP难问题,基本蚁群算法在求解该问题上收敛困难且寻优能力低。因此,本文提出了一种适合于翻箱模型的改进型蚁群算法,在概率决策机制、解的重构、信息素更新机制三个方面对基本蚁群算法进行改进。最后通过与其他算法的分析比较,验证了该改进算法的可行性与有效性。     

用于ALE有限元模拟的网格更新方法

任意拉格朗日欧拉法(ALE)可以通过定义参考网格的运动,实现自由液面跟踪,完成液体晃动的数值计算. 综合用于更新网格节点的3种基本计算方法,将多方向更新网格速度的技术应用于任意拉格朗日欧拉网格节点的速度计算. 给出了水平圆柱形贮箱和椭圆形贮箱内液体晃动算例,实现了多方向更新网格运动与晃动流场计算的耦合,使ALE方法能胜任复杂几何边界下的自由液面流动的数值模拟.      

储液容器跌落冲击动力学神经网络建模

运用LS-DYNA程序中的ALE算法模拟储液容器在不同的跌落角度、跌落高度、壳体厚度下的跌落冲击过程,获取神经网络预测模型的训练样本集;利用BP神经网络建立储液容器结构参数、跌落冲击参数与接触点最大应力之间的映射关系预测模型,并将各种参数下的接触点最大应力网络预测值与仿真值比较,两者差异较小,表明该方法是有效的,可以为实际生产过程中参数选择提供理论依据.     

Pure Log Terminal Blow-Ups

The existence of a pure log terminal blow-up for a log terminal singularity and a criterion for a singularity to be weakly exceptional are proved.     

手性(salen) Co配合物的合成及其在水解动力学拆分中的应用

综述了近几年来手性(salen) Co金属配合物的合成及其在水解动力学拆分末端环氧化合物中的应用。设计更合适的配体、发展可重复利用的催化剂、对催化剂及催化体系进行理论和模拟是当前乃至今后该领域研究工作的重点。