Model and nonlinear dynamic analysis of linear guideway subjected to external periodic excitation in five directions

Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are...     

20倍双组联动变焦距光学系统设计

针对双组联动变焦距系统结构复杂的特点,对其设计过程进行了梳理。在此基础上编制了可视化辅助设计软件,该软件具有高斯解计算、变倍补偿曲线绘制、像差与外形尺寸分析、相对孔径图输出等功能。使用该软件可以方便地完成双组联动变焦系统高斯解的合理选择,并给出各组元承担相对孔径及其变化情况,辅助进行初始结构的确定。利用该辅助设计软件,对一套焦距25~500 mm的20倍可见光波段双组联动连续变焦距系统进行了初始结构设计,并通过整体优化使系统像差得到校正。设计结果系统光学总长478 mm,各焦距位置在50 lp/mm处轴上视场调制传递函数(MTF)大于0.6,边缘视场MTF大于0.4,各项指标满足系统要求。     

化学计量学用于决明子色谱指纹图谱峰纯度的鉴别

应用化学计量学方法鉴别色谱指纹图谱的峰纯度。对背景进行扣除后,用对照组分光谱构建正交投影矩阵对目标色谱峰的光谱进行投影,以目标色谱峰投影后的残余光谱与投影前的原始光谱的夹角余弦为判据鉴别目标色谱峰的峰纯度：用该方法对决明子药材色谱指纹图谱的峰纯度进行识别,鉴别出大黄素、大黄酚和大黄素甲醚三个纯色谱峰。此方法用于色谱指纹图谱峰纯度的鉴别,结果可靠。     

航天光学遥感器在轨调制传递函数神经网络评价方法

通过对航天光学遥感器在轨调制传递函数模型和遥感图像的分析,找出遥感图像中与调制传递函数有关的特征信息,采用神经网络为工具,完成利用遥感器传输下来的任意一幅地面景物图像进行调制传递函数的评价。首先模拟出包含不同调制传递函数等级的遥感图像,组成训练样本集,再从图像中分别提取出直接与调制传递函数有关的特征参量和与景物结构有关的特征参量,作为神经网络的输入,网络通过对训练样本集中模拟出的大量调制传递函数已知的遥感图像训练后,当再次输入一幅调制传递函数未知的遥感图像时,便能够正确估计出其调制传递函数值。这种方法不需要在地面铺设靶标或预先获得调制传递函数已知的同一地面景物的航空图像作为参考,只需获得任意一幅地面景物图像即可完成对遥感器调制传递函数的评价。实验结果表明,当不考虑噪声对调制传递函数的影响时,对调制传递函数的评价误差约为6%,而在考虑噪声时,评价误差约为9%。     

Ultralow interfacial tension for enhanced oil recovery at very low surfactant concentrations

The interfacial tension (IFT) between alkanes and several individual surfactants and their mixtures has been investigated, using three kinds of alkyl hydrocarbons: decane, dodecane, and tetradecane. For individual and mixed surfactant systems, critical micelle concentrations and areas per molecule at the hydrocarbon-aqueous solution interface were calculated; for the mixed surfactant systems, betasigma(LL), the molecular interaction parameter at the hydrocarbon-aqueous solution interface, and beta(M), the molecular interaction parameter in mixed micelle formation, were calculated. It was found that IFT in the 10(-3) mN/m (ultralow) range can be obtained at surfactant concentrations below 0.05 wt % and even at concentrations below 0.01 wt %, when mixtures of certain surfactants are used at the proper ratio. Surfactants with branched-chain alkyl groups show a much better IFT reduction effectiveness than those with straight-chain alkyl groups. Contrary to what has been observed at the air-aqueous solution surface, mixtures of two homologues with two hydrophobic groups show significant molecular interactions, with both betasigma(LL) and beta(M) having negative values in the 4-5 range in some cases, with the betasigma(LL) value more negative than beta(M). The relationship between micellar shape and ultralow IFT was investigated by calculating the critical packing parameter of the surfactants. It was found that ultralow IFT between the surfactant mixtures and the three hydrocarbons investigated could reach ultralow (<10(-2) mN/m) values when the critical packing parameter is very close to 1.     

两性孪联表面活性剂的合成及溶液性质

用C10～C16脂肪醇与2-氯-2-氧-1,3,2-二氧磷杂环戊烷低温反应生成环状磷酸酯的中间产物,再用N,N-二甲基十二胺在亲核溶剂中65℃下开环反应合成了4种含N 和磷酸根阴离子的两性孪联表面活性剂C10-C12、C12-C12、C14-C12和C16-C12,其质量收率分别为32%、54%、18%和28%。产物的结构通过1HNMR和元素组成分析,表明两性离子表面活性剂C、H、O、N的分析值与理论计算值偏差不超过0.3%。四种表面活性剂的临界胶束浓度(cmc)在0.0072~0.0125mmol/L之间,临界胶束浓度时表面张力(γcmc)依次为23.90、25.61、27.68和36.08mN/m。其中,C10-C12、C12-C12和C14-C12有较好的界面活性,加入盐可以使表面活性剂与烷烃间的界面张力下降,但下降程度有限,不能达到超低界面张力(10-3mN/m)。     

BP网络光度法测定去痛片中的四组分

应用Levenberg-Marquardt优化算法的BP网络,采用紫外分光光度法测定去痛片中四组分的含量。测定低含量组分咖啡因和苯巴比妥时,结合吸光度减法技术。氨基比林、非那西丁、咖啡因和苯巴比妥的平均回收率和RSD分别为99.3%,1.2%：;100.0%,1.1%;100.3%,1.5%;100.1%,1.3%。     

Fragmentation pathways of protonated coumarin by ESI‐QE‐Orbitrap‐MS/MS coupled with DFT calculations

Coumarin is one of the basic structures of naturally oxygen heterocyclic compound, which was investigated in this paper for its gas‐phase fragmentation behaviors using electrospray quadrupole extractive orbitrap mass spectrometry in the positive mode. The possible fragmentation pathways were proposed based on electrospray ionization (ESI)‐ mass spectrometry (MS)/MS data and theory calculation. The elimination of two CO and CO₂ was observed for protonated coumarin, which was followed by the formation of a stabilized seven‐, six‐, and five‐membered ring carbocation by loss of C2H2. The possible protonation sites occurred at Oxygen 11 atom of coumarin were the main fragmentation pathways. The relative abundance of characteristic fragment ions and the energy‐resolved breakdown curves were used to confirm the cleavage mechanism of protonated coumarin. The methodology and results of present work would contribute to the chemical structure identification of other coumarins.     

多用途、模块化哈特曼波前传感器的研制

分析了哈特曼传感器的主要设计指标,介绍了设计研制的一种多用途、模块化哈特曼传感器,通过将传感器的主要部件,包括光源、准直镜、分光棱镜、缩束光路、微透镜阵列及相机等进行模块化设计,根据不同需求,对各模块增减或更换,实现了一套传感器多种用途的应用.并用该传感器进行了系统波像差及光学元件面形检测实验,通过与Zygo干涉仪的测...     

空间紫外遥感仪器光谱响应度定标环境的研究

为了减小空间紫外遥感仪器(SURSI)光谱响应度定标不确定度,实现SURSI在轨的高精度探测,对SURSI定标环境进行了深入的分析研究。利用光学薄膜的电磁场理论数值计算出铝+氟化镁膜在250～400nm波段,真空和大气两种环境下的反射率值并进行比对。通过构建SURSI真空/大气响应度比对测试研究系统,对SURSI整机光谱响应度在两种环境下的差异进行了实验研究,在250～400nm波段,平均偏差可达3.8%。理论分析及实验结果表明:受仪器内部光学元件铝+氟化镁膜光学性质的影响,SURSI光谱响应度在真空和大气不同环境下存在明显差异,且偏差值具有波长相关性,直接说明SURSI辐射定标在真空环境下完成的必要性。