用标准件对梯度磁场定标

就标准厚度卡片在霍尔传感器的定标方面的应用作了有益的探讨。在纵向测量微小长度时,霍尔片处于磁场边缘位置,其对磁场的梯度更大,即灵敏度更高,且靠中心位置的线性更好。     

Performance of a sound card as data acquisition system and a lock-in emulated by software in capillary electrophoresis

The performance of fluorescence detectors in capillary electrophoresis is maximized when the excitation light intensity is modulated in time with optimal frequencies. This is especially true when photomultiplier tubes are used to detect the fluorescent light. The photomultiplier tube amplified raw output signal can in principle be captured directly by a personal computer sound card (PCSC) and processed by a lock-in emulated by software. This possibility is demonstrated in the present work and the performance of this new setup is compared with a traditional data acquisition system. The results obtained with this “PCSC and lock-in emulated by software” were of the same quality or even better compared to that obtained by conventional time integrators (Boxcars) and data acquisition boards. With PCSC the limits of detection (LOD) found for both naphthalene-2,3-dicarboxaldehyde-derivatized tyrosine and alanine were 3.3 and 3.5 fmol (injection of 5 nL of samples at 0.66 and 0.70 μmol/L), respectively. This is at least three times better compared to conventional systems when light emitting diodes (LEDs) are used as the excitation source in fluorescence detectors. The PCSC linear response range was also larger compared to conventional data acquisition boards. This scheme showed to be a practical and convenient alternative of data acquisition and signal processing for detection systems used in capillary electrophoresis.     

基于彩色扫描仪的图像光谱重构

针对彩色扫描仪的特点,采用主元分析法(PCA)和反向传播(BP)人工神经网络(ANN)相结合的方法对图像光谱重构进行研究。选择IT8.7/2标准色卡作为训练样本,将该色卡中的另一组色靶作为检验样本以讨论不同网络结构以及不同主元数和训练样本数对光谱重构的影响,再以自然色系统(NCS)色卡为检验样本来分析不同种类的训练和检验样本与光谱重构性能的关系。实验结果表明,采用3-14-6网络结构和6个主元数是最佳选择,训练样本和扫描目标之间的一致性是基于彩色扫描仪图像光谱重构的关键所在。     

A new modified remote user authentication scheme using smart cards

In 2000, a remote user authentication scheme using smart cards was proposed and the masquerade attacks were proved successful on this scheme. Recently, Kumar has suggested the idea of check digits to overcome the above attacks with a new scheme that removes these threats well. In this paper it is pointed out that the weakness still exists in Kumar＇s scheme, and the intruder can login to the remote system through having some information. A new scheme which can overcome these attacks and appears more secure and efficient than Kumar＇s is presented.     

食堂智能卡管理系统

本文全面介绍了通过使用最新推出的智能卡(IC卡)技术，结合51系列单片机而研制的食堂智能卡管理系统，替代了原食堂繁琐的饭票流通，实现了食堂管理的电脑化.     

马尔可夫链模型在信用卡账户行为变化预测中的应用

对信用卡账户行为变化的监控是降低信用卡风险的关键.论文在构建马尔可夫模型的基础上,讨论了在信用卡账户无新增贷款、新增贷款固定不变和新增贷款发生周期性变化的情况下,如何预测信用卡账户不同状态的金额、已偿付态和坏账态的金额、全部应收款的现值及它们的方差计算等内容,为信用卡账户行为变化的预测、管理提供了方法和依据.     

一个安全有效的智能卡远程用户认证方案

2000年,Hwang和Li提出了一个新的智能卡远程用户认证方案,随后Chan和Cheng对该方案进行了成功的攻击.最近Shen,Lin和Hwang针对该方案提出了一种不同的攻击方法,并提供了一个改进方案用于抵御这些攻击.2003年,Leung等认为Shen-Lin-Hwang改进方案仍然不能抵御Chan和Cheng的攻击,他们用改进后的Chang-Hwang攻击方法进行了攻击.文中主要在Hwang-Li方案的基础上,提出了一个新的远程用户认证方案,该方案主要在注册阶段和登录阶段加强了安全性,抵御了类似Chan-Cheng和Chang-Hwang的攻击.     

一种新型的化学离子敏（1）一次性血液电解质钾、钠测试卡片的研制和应用

新型的一次性化学离子敏钾、钠测试卡片，是基于离子选择电极（ＩＳＥ）原理设计制作的一种电化学传感器~［１］。它由测量电池装置、敏感膜、接触衬底（石墨）和盐桥等构件组装而成。采用两点电位测量法。具有一次性使用、简便、快速、精确度高、成本低等优点，对样品不必作预处理，避免了交叉污染，克服了ＩＳＥ重现性差、固有漂移等缺点，发挥了ＩＳＥ选择性好、准确度高等优点。根据临床应用和抽样测试结果，钾、钠测试卡片的精密度±ＳＤ：钾１．０；钠２．０，Ｃ．Ｖ％：钾３．０％；钠２．０％；响应时间为３０ｓ；漂移：钾０．３ｍＶ／ｍｉｎ；钠０．５ｍＶ／ｍｉｎ；回收率为９９．５％，均符合临床应用的基本要求。     

基于多功能数据采集卡和变速PID的转台控制系统设计

为了提高采用转台对惯导系统和惯性仪表进行误差模型标定时的可靠性和精度,对角位置转台的控制系统进行了研究。首先借助NI公司PXI-8101控制器和功能强大的数据采集卡PXIe-6363对转台控制系统进行了硬件设计。随后在对转台常规PID控制方法研究的基础上提出了一种能随系统调节偏差自动改变积分项累加速度的变速PID控制方法。接着又对基于软件实现的双通道旋转变压器轴角解调算法进行了研究并提出了一种粗精组合角纠错方法。最后对本文设计的转台控制系统进行了测试实验,结果表明提出的轴角解调算法具有较好的解码速度和精度,并且变速PID控制方法大大提高了转台控制系统的自学习能力和鲁棒性,显著地改善了转台控制过程的稳定性。     

Raman Spectroscopy Analysis of a Playing Card from the 18th Century

We present the characterization, by means of three complementary experimental techniques (optical microscopy [OM], scanning electron microscopy equipped with energy dispersive X-Ray spectroscopy [SEM-EDX], and micro-Raman spectroscopy [µRaman]), of a card belonging to a deck of the Spanish pattern made in Perú at the time of Virreinato de Perú (18th century). The objective is to obtain detailed information on the pictorial palette used for the decoration of the cards, where two basic colors, red and green, are seen. Small samples from both colored regions were analyzed.