Nonlinear analysis of a simple amplitude–phase motion equation for power-electronics-based power system

Nonlinear Dynamics - With large-scale application of a large number of renewable energy sources, such as wind turbines, photovoltaics, and various power electronic equipment, the power electric...     

Characteristics of the Decomposition of CO2 in a Dielectric Packed-Bed Plasma Reactor

The decomposition of CO₂ in a dielectric packed-bed plasma reactor has been studied. It was found that the dielectric properties and morphology of packing dielectric pellets play important roles in the reaction due to their influence on the electron energy distribution in the plasma. The acid–base properties of the packing materials also affect the reaction through the chemisorption of CO₂ on basic sites of the materials. Heterogeneous reactions on the solid surfaces of the dielectric materials also play a role in the reaction, which was also confirmed through the investigation of the influence of the discharge length on the reaction. The reverse reaction of CO₂ decomposition, the oxidation of CO, was also investigated to further understand the role of dielectric materials in the plasma and their effect on plasma reactions. Both the decomposition of CO₂ and the oxidation of CO in non-packed or dielectric packed reactors are first-ordered.     

Fe73．5 Cu1 Nb3 Si13．5 B9非晶合金带材的压磁特性

采用电感式压磁效应测试方法直接测试和表征了铁基非晶合金带材的压磁效应。结果表明,铁基非晶合金带材在 f＝1kHz 频率下的压磁效应最大,并且带材对小于0．2 MPa 压应力非常敏感。对带材退火处理后,压磁效应增大。在测试频率 f＝1 kHz、连续压应力加／卸载过程中,随着退火温度的升高,Fe73．5 Cu1 Nb3 Si13．5 B9带材压磁效应值增大。当退火温度550℃时,带材压磁效应最大,其压磁效应值 SI（％）max 为1．4。     

混合模式色谱分离材料的研究及其应用进展

近年来混合模式色谱以其独特的分离特性受到人们越来越多的关注。混合模式色谱的种类主要集中在反相/离子交换混合模式色谱(reversed-phase/ion-exchange mixed-mode chromatography, RPLC/IEX),亲水作用/离子交换混合模式色谱(hydrophilic interaction/ion-exchange mixed-mode chromatography, HILIC/IEX),反相/亲水作用混合模式色谱(reversed-phase/hydrophilic interaction mixed-mode chromatography, RPLC/HILIC)等混合模式。两种或多种机理混合使用,往往在分离选择性和色谱峰形等方面能得到不同于单一模式操作所得到的效果,分离选择性以及色谱峰形等都能得到极大的改善与提高,这使得混合模式色谱渐渐进入研究者们的视野。混合模式色谱的研究多数集中在色谱填料的设计。混合模式色谱填料的应用主要针对生物样品的分离分析。该文综述了近年来混合模式色谱的研究及其应用进展,并展望了混合模式色谱的发展。     

氨水介质和氟处理对铝柱层柱粘土性质的影响

 分别在氨介质和钠介质中制备了层柱蒙脱土和层柱累托石,并用氟化铵、氟硅酸铵和氟铝酸铵对层柱粘土进行处理,考察了处理条件对层柱粘土结构和酸性的影响. NH3-TPD和IR分析结果表明,氨介质中制备的层柱粘土比钠介质中制备的具有更强的酸性,经氟处理后层柱粘土的酸性有较大的提高. 氨介质中制备的层柱粘土的低钠含量是其酸性改善的主要原因,而氟处理对层柱粘土酸性的提高主要来自氟对铝柱的表面作用. 氟处理层柱粘土对异丙苯裂解具有很高的催化活性.     

钇铝石榴石对撞增强型相位共轭腔的研究

报道了一种新型的相位共轭腔——对撞型钇铝石榴石受激布里渊散射相位共轭激光腔,实验结果发现该腔具有较低的启动阈值和100mJ以上的输出能量,它能输出稳定的20ns左右的自调Q脉冲,发散角为1．3mrad。在一定范围内,抽运电压越高,输出脉宽越窄;相位共轭腔越长,输出脉宽越宽;聚焦透镜对输出脉宽也有影响,焦距越短,脉宽越窄;焦距与介质池相对长点,输出能量相对高,远场发散角相对小些。实验给出了不同条件下的输出能量、脉冲宽度和光束发散角的情况。     

多波长双向抽运光纤拉曼放大器的优化设计

通过合理分析提出了便于计算多波长双向抽运光纤拉曼放大器信号及噪声功率的实用数值模型,给出求解信号和噪声功率的快速算法。在定义抽运方向度为前向抽运功率与总抽运功率值的比值后,通过对计算结果的分析发现信道平均放大自发辐射噪声功率随着抽运方向度的提高而单调递减;而信道平均双重瑞利散射噪声功率相对抽运方向度的变化曲线始终成U字形。不同的增益下存在对应的最优抽运方向度,在此抽运方向度下放大器总噪声最低。进而考虑在信号非线性失真的条件下提出了抽运方向度优化的衡量指标。优化后的多波长双向抽运方式不仅能保证对所有信道的平坦放大,而且其综合性能明显高于后向抽运方式。     

Asymmetric Cyanation of Aldehydes,Ketones, Aldimines,and Ketimines Catalyzed by a Versatile Catalyst Generated from Cinchona Alkaloid,Achiral Substituted 2,2′‐Biphenol and Tetraisopropyl Titanate

Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)₄] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved for the Strecker reaction of N‐Ts (Ts=p‐toluenesulfonyl) aldimines and ketimines (up to >99 % yield and >99 % ee) as well as for the cyanation of ketones (up to 99 % yield and 98 % ee). By using CNCOOEt as the alternative cyanide source, cyanation of aldehyde was accomplished and various enantioenriched cyanohydrin carbonates were prepared in up to 99 % yield and 96 % ee. Noteworthy, CNCOOEt was successfully employed for the first time in the asymmetric Strecker reaction of aldimines and ketimines, affording various α‐amino nitriles with excellent yields and ee values (up to >99 % yield and >99 % ee). The merits of current protocol involved facile availability of ligand components, operational simplicity and mild reaction conditions, which made it convenient to prepare synthetically important chiral cyanohydrins and α‐amino nitriles. Furthermore, control experiments and NMR analyses were performed to shed light on the catalyst structure. It is indicated that all the hydroxyl groups in cinchona alkaloid and biphenol complex with Ti^IV, forming the catalyst with the structure of (biphenoxide)Ti(OR*)(OiPr). The absolute configuration adopted by biphenol 4 m in the catalyst was identified as S configuration according to the evidence from control experiments and NMR analyses. Moreover, the roles of the protonic additive (iPrOH) and the tertiary amine in the cinchona alkaloid were studied in detail, and the real cyanide reagent in the catalytic cycle was found to be hydrogen cyanide (HCN). Finally, two plausible catalytic cycles were proposed to elucidate the reaction mechanisms.     

含有NH2CH2CH2CH2NH2和o-C6H4(NH2)2配体的镍配合物的合成、结构和它们在乙烯聚合中的作用

两种镍的配合物[Ni(NH2CH2CH2CH2NH2)3]Cl2 (1)和[Ni(C6H4N2H4)2Cl2] (2)已经被合成并且通过红外和单晶X射线衍射分析对其进行了表征。在配合物1中,镍原子处于手性假八面体[NiN6]的几何构型中,它与三个1,3-丙二胺分子形成了三个六元环。在配合物2中,镍原子除了与两个o-苯二胺分子通过四个Ni-N键形成两个五元环外,它还与两个Cl原子配位形成了反式Ni-Cl2,这不同于以往报道过的镍的二胺配合物。这两个镍的配合物被MAO, MMAO或Et2AlCl活化后,对乙烯的二聚合或三聚合显示了很好的催化活性[对于配合物2,催化活性达到3.59×106 g mol-1 (Ni) h-1]。