A systematic approach to standard addition methods in instrumental analysis

Nine cases of standard addition methods in instrumental analysis, including linear instruments, a non-linear response, the electrochemical Nernst equation, and radiochemical techniques.

Studies of instrumental spreading in gel permeation chromatography by coupling with a two-angle laser light scattering detector

The instrumental spreading of a high temperature gel permeation chromatograph (GPC) was evaluated by coupling with a two-angle laser light scattering (TALLS) detector, using narrow polystyrene, polyethylene, and syndiotactic polypropylene samples. The determined spreading factor increased with increasing molecular weight of polymers, and no maximum for spreading 174 tor was observed in the studied retention volume, while the spreading factors for single low molecular weight alkanes are independent of their molecular weight. Neglecting of the spreading effect for GPC would not introduce much error in molecular weight calculation when high quality high performance columns were used, especially when equipped with a laser light scattering detector. The scaling relationship between radius of gyration and molecular weight of polymer, determined by GPC with a TALLS detector, was independent of the instrumental spreading.

透镜自重变形引起波像差的有限元分析

在用大口径、长焦距平行光管模拟激光远场特性时，其光组透镜在重力作用下的变形不能忽略，为了分析对出射光束质量的影响，采用有限元分析软件“ANSYS”建立了平行光管光组中声400mm平凸透镜的有限元模型，给出一种分析透镜轴向变形引起的波像差的方法，在不同工况下，计算了平凸透镜在重力作用下轴向变形的峰谷值和均方根值，对轴向变形量均方根值最小工况画出了透镜表面变形的等值线图，计算了声350mm通光口径内的波像差峰谷值和均方根值，对平行光管光组的波像差做出估计，验证了设计的合理性。

Structure approximate based on double weighted neural network

Double weighted neural network; is a kind of new general used neural network, which, compared with BP and RBF network, may approximate the training samples with a move complicated geometric figure and possesses a even greater approximation. capability. we study structure approximate based on double weighted neural network and prove its rationality.

基于度量工具的软件成本估算模型使用方法

输入的主观性以及输入过多是妨碍软件成本估算模型实际应用效果的重要影响因素.针对以上问题,提出了一种基于度量工具的软件成本估算模型使用方法.该方法通过引入统计理论中的工具变量,将度量工具所采集的度量元数据自动转换为软件成本估算模型的输入.这一方面可以避免模型校准和估算过程中输入的主观性与不一致性,提高了估算结果的准确性与可靠性;另一方面能减少估算人员的手工操作,提高工作效率,增加了软件成本估算模型的可用性.结合具体实例说明了所提出方法的可行性与有效性.

Characteristics of electroosmotic flow and migration of neutral solutes under stepwise gradient elution of capillary electrochromatography

A theoretical study on the velocity of electroosmotic flow (EOF) and the retention times of neutral solutes under multiple-step gradient of capillary electrochromatography (CEC) was carried out, focusing on that with three kinds of mobile phases. Through the model computations, the detaining time of the second kind of mobile phase in the column was proved to play an important role in affecting EOF. The variation speed of EOF was shown to be determined by the differences among dead times in different steps. In addition, the prediction of the retention times of 13 aromatic compounds under gradient mode was performed with the deduced equations. A relative error below 3.3% between the calculated and experimental values was obtained, which demonstrated the rationality of the theoretical deduction. Our study could not only improve the comprehension of stepwise gradient elution, but also be of significance for the further optimization of separation conditions in the analysis of complex samples.