微乳液毛细管电动色谱研究

本文研究了两组混合样的微乳液毛细管电动色谱(MEEKC)分离, 较系统地研究了微乳液的内相, 助表面活性剂及其浓度对电动分离的迁移时间、柱效及时间窗的影响, 并与胶束毛细管电动色谱(MEKC)分离进行了比较, 选用由80mmol/L正辛烷-120mmol/L十二烷基硫酸钠-900mmol/L正丁醇-10mmol/L硼砂组成的微乳液, 样品组分电动色谱迁移时间的RSD<0.8%, 峰面积RSD<3.0%.     

高效液相色谱法测定洗手液中水杨酸和对氯间二甲苯酚

建立高效液相色谱仪同时测定洗手液中水杨酸和对氯间二甲苯酚含量的方法。采用Shim-pack Scepter C18柱(250 mm×4.6 mm,5 μm),流动相为甲醇–0.1%磷酸水溶液(体积比为70∶30),流量为1.0 mL/min,柱温为室温,检测器为岛津SPD–M20A二极管阵列检测器,检测波长为280 nm。水杨酸和对氯间二甲苯酚与色谱峰面积呈良好的线性关系,线性范围分别为40~400 μg/mL,20~200 μg/mL,相关系数均为r^2=0.999 9。方法的检出限为0.1 μg/mL,水杨酸和对氯间二甲苯酚测定结果的相对标准偏差分别为0.79%,1.39%(n=5),加标回收率为96.9%~99.8%。该方法方法简便、快速、灵敏度高、重现性好,能同时准确检测洗手液中水杨酸和对氯间二甲苯酚的含量。     

奇摄动半线性系统的边界层和角层性质

一些作者已对纯量边值问题εy"=h(t,y),a相似文献   

非线性边值问题的奇摄动

本文研究边值问题:εy"=f(x,y,y',ε,μ)(μ0(ε,μ)y(x,ε,μ)|(x=1-μ)=φ₁(ε,μ)其中ε,μ是两个正的小参数 在f_y’≤-k<0和其他适当的限制下,存在一个解且满足其中y₀,0(x)是退化问题 f(x,y,y',0,0)=0(01(0,0)的解,而y_i-j,j(x)(j=0,1,…,i;i=1,2,…m)能够从某些线性方程逐次求得.     

SINGULAR PERTURBATION OF NONLINEAR BOUNDARY VALUE PROBLEMS

In this paper we consider the boundary value problem where ε.μ are two positive parameters. Under f_y≤-k<0 and other suitable restrictions, there exists a solution and it satisfied where y_(0,0)(x) is solution of reduced problem while y_i-j,j(x)(j=0,1,...,i;i=1,2,...,m) can be obtained successively from certain linear equations.     

参变极值问题的信息凝聚分布与Boltzmann极大熵函数

该文利用Ｂｏｌｔｚｍａｎｎ 熵概念给出了参变极值问题最优解的一种积分极限表达式和极值函数的极大熵函数,讨论了它们一致收敛性的要求并给出了极大熵函数一致收敛的一个充分条件,将之应用到全局最优解问题得到了全局最优解和最优值的一种显表示,最后还探讨了极大熵函数在一类双层规划问题求解中的应用．     

Dynamical analysis and experimental verification of valley current controlled buck converter

The dynamical behaviours of valley current controlled buck converter are studied by establishing its corresponding discrete iterative map model in this paper. Time-domain waveforms and phase portraits of valley current controlled buck converter are obtained by Runge--Kutta algorithm through a piecewise smooth switching model. The research results indicate that the valley current controlled buck converter exhibits rich nonlinear phenomena, and it has routes to chaos through period-doubling bifurcation and border-collision bifurcation in a wide parameter range. Interesting inverse nonlinear behaviours compared with peak current controlled buck converter are observed in the valley current controlled buck converter. Analysis and simulation results are verified by experimental results.     

A hybrid-stress element based on Hamilton principle

A novel hybrid-stress finite element method is proposed for constructing simple 4-node quadrilateral plane elements, and the new element is denoted as HH4-3fl here. Firstly, the theoretical basis of the traditional hybrid-stress elements, i.e., the Hellinger-Reissner variational principle, is replaced by the Hamilton variational principle, in which the number of the stress variables is reduced from 3 to 2. Secondly, three stress parameters and corresponding trial functions are introduced into the system equations. Thirdly, the displacement fields of the conventional bilinear isoparametric element are employed in the new models. Finally, from the stationary condition, the stress parameters can be expressed in terms of the displacement parameters, and thus the new element stiffness matrices can be obtained. Since the required number of stress variables in the Hamilton variational principle is less than that in the Hellinger-Reissner variational principle, and no additional incompatible displacement modes are considered, the new hybrid-stress element is simpler than the traditional ones. Furthermore, in order to improve the accuracy of the stress solutions, two enhanced post-processing schemes are also proposed for element HH4-3β. Numerical examples show that the proposed model exhibits great improvements in both displacement and stress solutions, implying that the proposed technique is an effective way for developing simple finite element models with high performance.     

激光自混合效应在光纤压力传感中的应用

设计了一种结合半导体激光器自混合效应和光纤传感技术进行测压的方法。通过仿真分析,证明此方法结合了两种技术的优点,具有量程大、抗干扰等特点。测量精度为47.6 N/Hz,可用于建筑、桥梁和道路等大型工程健康状况的监测。     

三(2,6-二叔丁基-4-甲基-苯氧基)镧催化ε-己内酯低温聚合特征及与环碳酸酯嵌段共聚

摘要用三(2,6-二叔丁基-4-甲基-苯氧基)镧[La(OAr)₃]在-15 ℃引发ε-己内酯(CL)的开环聚合, 发现聚合体系具有活性聚合特征. 在第二步聚合过程中继续补加第二种单体三亚甲基环碳酸酯(TMC)或二甲基三亚甲基环碳酸酯(DTC), 可得到CL与环碳酸酯的嵌段共聚物.