二极管泵浦自启动附加脉冲锁模Nd:YLF激光器

实现了激光二极管泵浦Nd:YLF激光器的自启动附加脉冲锁模,工作波长1053um,得到2.8ps的超短脉冲,重复频率130MHz,有效输出功率70mW.     

基于功图分析的有杆抽油泵故障诊断技术研究

在油井开采中,利用计算机技术准确判断油井井下故障,实现采油系统的数字化与智能化,是当今石油行业急需解决的重大难题之一。通过示功图分析诊断有杆抽油泵故障是油田分析泵况的主要手段,目前,国内外对示功图的识别还是主要依靠人完成,虽然计算机识别技术早已实现,但是,由于其准确度有限,并未得到推广。本文以文献研究为基础,首先介绍了抽油泵故障诊断技术的发展历程,对井下泵功图转换模型建立、泵功图特征值提取方法和特征值匹配方法的国内外功图识别技术进行了分析,指出了目前有杆泵故障诊断技术中存在的主要问题及今后需要努力的方向。     

Stereoretention in styrene heterodimerisation promoted by one-electron oxidants

Radical cations generated from the oxidation of C C π-bonds are synthetically useful reactive intermediates for C–C and C–X bond formation. Radical cation formation, induced by sub-stoichiometric amounts of external oxidant, are important intermediates in the Woodward–Hoffmann thermally disallowed [2 + 2] cycloaddition of electron-rich alkenes. Using density functional theory (DFT), we report the detailed mechanisms underlying the intermolecular heterodimerisation of anethole and β-methylstyrene to give unsymmetrical, tetra-substituted cyclobutanes. Reactions between trans-alkenes favour the all-trans adduct, resulting from a kinetic preference for anti-addition reinforced by reversibility at ambient temperatures since this is also the thermodynamic product; on the other hand, reactions between a trans-alkene and a cis-alkene favour syn-addition, while exocyclic rotation in the acyclic radical cation intermediate is also possible since C–C forming barriers are higher. Computations are consistent with the experimental observation that hexafluoroisopropanol (HFIP) is a better solvent than acetonitrile, in part due to its ability to stabilise the reduced form of the hypervalent iodine initiator by hydrogen bonding, but also through the stabilisation of radical cationic intermediates along the reaction coordinate.

A computational study details the mechanism, catalytic cycle and origins of stereoselectivity underlying hole-catalyzed intermolecular alkene heterodimerisation to give unsymmetrical, tetra-substituted cyclobutanes.     

水系锌离子电池用钒基正极材料的研究进展

水系锌离子电池(aqueous zinc-ion batteries,AZIBs)具有高安全性、低生产成本、锌资源丰富和环境友好等优点,被认为是未来大规模储能系统中极具发展前景的储能装置。目前,AZIBs的研究关键之一在于开发具有稳定结构和高容量的锌离子可脱嵌正极材料。钒基化合物用作AZIBs正极时,表现出可逆容量高和结构丰富可变等特点,受到了广泛的关注和研究。然而,钒基化合物的储锌机理较复杂,不同材料通常表现出各异的电化学性能和储能机理。在本综述中,我们全面地阐述了钒基化合物的储能机制,并探讨了钒基材料在水系锌离子电池中的应用和发展近况,以及它们的性能优化策略。在此基础上,也进一步地展望了水系锌离子电池及其钒基正极材料的发展方向。     

Acid-mediated three-component aza-Diels-Alder reactions of 2-aminophenols under controlled microwave heating for synthesis of highly functionalized tetrahydroquinolines. Part 9: Chemistry of aminophenols

The aza-Diels-Alder reactions of two 2-aminophenols in combination with six substituted benzaldehydes and two electron-rich cyclic alkenes were investigated under controlled microwave heating. The reactions were carried out in the presence of a catalytic amount of CF₃CO₂H in MeCN at 60 °C for 15 min, affording highly functionalized 8-hydroxy-1,2,3,4-tetrahydroquinolines in 39-59% isolated yields and in 36:64-16:84 diastereomer ratios in favor of the trans isomers. The microwave-heated three-component aza-Diels-Alder reactions completed in significantly reduced reaction time to give the same level of chemical yield and diastereomer ratio obtained from the room temperature reaction.     

K9玻璃低压下的双折射效应研究（Ⅱ）

继文献[1]之后,我们又用激光外差干涉仪测量了K9玻璃低压(0～3.5kg)下的双折射率,发现△~n_o～F和△~n_o～F呈不同的变化规律,这个现象是由样品内部应力分布的不均匀所导致的,反映了实际天文透镜自重引起的双折射率变化。     

基于分布链修正的磁流变弹性体的物理模型

On the basis of distributed chains, the model of MR elastomer was revised. After the potential energy of a chain was analyzed using the local field method, a special function was used to describe the distribution of chains. Then the MR effect of distributed chains as well as the overall MR effect were studied. Concurrently, the effects of the curing magnetic field and the matrix were incorporated into the model of MR elastomer.     

热色液晶无损检测技术

本文介绍了热色液晶在无损检测技术中的应用研究，并获得了非常成功的结果。通过液晶显示出的缺陷周围温度分布的色彩奇异性，可以明显地指示出缺陷的位置。     

Concise Synthesis of JN403, a Novel Nicotinic Acetylcholine Receptor α7 Selective Agonist

A three-step method for the synthesis of (S)-(1-aza-bicyclo[2.2.2]oct-3-yl)carbamic acid (S)-1-(2-fluorophenyl)ethyl ester HCl salt (12) was developed, starting from alcohol 3 and resulting in an overall yield of 50%. A key feature of the present study is the need to use a strong base such as n-butyllithium for neutralizing the HCl salt of 5 during the condensation of 4 with 5.     

基于单像素成像的微小位移测量方法

激光散斑位移测量法是一种重要的现代光学位移测量方法,由于受到图像传感器元件感光性能限制,难以在强干扰光条件下获得有效散斑场信息,进而无法获取位移场数据,因此,基于单像素成像技术,本文提出一种新的激光散斑位移测量方法:对散斑信息进行图案编码调制,并使用单像素探测器采集调制后的光强信息;利用Walsh-Hadamard Transformation(WHT)成像算法对散斑场图像进行重建;最后结合自相关算法确定物体的位移场信息。分别利用商业相机和单像素成像技术对散射介质的单轴微小位移进行测量,结果表明基于单像素成像技术的激光散斑位移测量技术可以获得较好的测量结果。相比于传统测量方法,基于单像素成像技术的激光散斑位移测量方法在复杂环境中具有一定的优势,可实现强光干扰下的位移场测量。