Rare-Earth Catalyzed C−H Bond Alumination of Terminal Alkynes

Organoaluminum reagents’ application in catalytic C−H bond functionalization is limited by competitive side reactions, such as carboalumination and hydroalumination. Herein, rare-earth tetramethylaluminate complexes are shown to catalyze the exclusive C−H bond metalation of terminal alkynes with the commodity reagents trimethyl-, triethyl-, and triisobutylaluminum. Kinetic experiments probing alkyl-group exchange between rare-earth aluminates and trialkylaluminum, C−H bond metalation of alkynes, and catalytic conversions reveal distinct pathways of catalytic aluminations with triethylaluminum versus trimethylaluminum. Most significantly, kinetic data point to reversible formation of a unique [Ln](AlR₄)₂⋅AlR₃ adduct, followed by turnover-limiting alkyne metalation. That is, C−H bond activation occurs from a more associated organometallic species, rather than the expected coordinatively unsaturated species. These mechanistic conclusions allude to a new general strategy for catalytic C−H bond alumination that make use of highly electrophilic metal catalysts.     

Optimal Control of a Ship for a Course-Changing Maneuver

The steering control of a ship during a course-changing maneuver is formulated as a Bolza optimal control problem, which is solved via the sequential gradient-restoration algorithm (SGRA). Nonlinear differential equations describing the yaw dynamics of a steering ship are employed as the differential constraints, and both amplitude and slew rate limits on the rudder are imposed. Two performance indices are minimized: one measures the time integral of the squared course deviation between the actual ship course and a target course; the other measures the time integral of the absolute course deviation. Numerical results indicate that a smooth transition from the initial set course to the target course is achievable, with a trade-off between the speed of response and the amount of course angle overshoot.     

堆浸工艺中流动-反应-变形-传质耦合过程数值模拟及应用

基于堆浸过程中的孔隙变形,发展了一孔隙发育模型,并建立了堆浸工艺中流动-反应-变形-传质全耦合模型控制方程组,在喷淋强度不变和常水头的的情况下,给出了方程的数值解.数值结果描述了浸出过程矿堆中溶浸液饱和度的分布、溶浸剂浓度和浸出矿石浓度的分布,拟合结果表明:有用矿物浸出百分比与浸出时间之间呈3次关系,这一关系可用来预测堆浸中的有用金属的浸出回收率.     

有界随机噪声激励下一类非线性系统的共振与饱和现象

研究了二自由度非线性系统在有界随机噪声激励下,系统响应的共振与随机饱和现象。用多尺度法分离了系统的快变项,用线性化方法求出了系统响应幅值的一、二阶矩,并给出了系统优化设计的一些建议。数值模拟表明本文提出的方法是有效的。     

分立式色散补偿拉曼放大器增益特性及非线性现象研究

分立式色散补偿拉曼放大器具有兼顾色散补偿和信号放大的特点，在通信系统中展现出广阔的应用前景.对反向抽运的C波段色散补偿分立式拉曼放大器的增益谱形状，增益饱和及受激布里渊散射等特性进行了较为详细的实验研究. 关键词： 分立式色散补偿拉曼放大器 增益饱和 受激布里渊散射 斯托克斯波     

大功率非晶态变压器磁偏饱和的预防方法

概述了非晶态材料的基本特性，深入分析了大功率非晶态变压器出现磁偏移饱和现象的原因，提出了幅值递增法，脉宽递增法和电流积分调宽法等预防磁偏饱和的方法. 关键词： 非晶态磁偏饱和 幅值递增法 脉宽递增法 电流积分调宽法     

球面卷积算子的饱和阶

本文给出了确定球面卷积算子饱和阶的一般方法并举例说明了它的应用．     

The Approximation Properties of Certain Interpolation Operators of Entire Exponential Type （Ⅱ）

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具有外部输入和偏差的细胞神经网络的完全稳定性

本文证明了对于由两个细胞组成的细胞神经网络，外部输入和偏差不影响网络的稳定平衡点的存在性和完全稳定性．     

“四靶串接”类氖锗软X光激光趋向饱和增益的理论研究

介绍了“四靶串接”设计思想,继对接方式之后,又提出了顺接方式来提高X光激光增益,使四靶总长度达到5.6cm。我们研制了程序系列来模拟这一实验,直接给出测点处的X光激光的强度。先用上轮“双靶对接”实验结果检验我们的程序系列,使得23.2nm激光线的结果与实验数据相符合,再用它模拟“四靶串接”实验。在实验之前,对各靶之间距离和角度,以及这些数据对实验结果的敏感程度作了预估,用以指导实验。实验结果证明理论模拟是正确的。23.2nm和23.6nm两条激光线已明显趋于饱和,其小讯号增益长度积GL分别达到18.3和17.6,有效GL分别达到16.4和15.7。X光激光的发散角已减小到3～4mrad,超过美国利弗莫尔实验室(LLNL)已发表的最好结果。