一种简单的基于字符形状的验证码识别技术

针对传统的基于模板匹配和字符结构的验证码识别技术对字符大小、倾斜等因素非常敏感,提出了一种基于字符形状特征的验证码识别方法,该方法是模拟人眼通过事物形状特征来识别事物.通过相应算法提取字符特征,然后根据字符所满足的一系列特征来判断是哪一个字符.与传统识别方法相比,该方法具有不受字符大小、倾斜等因素影响的优点.实验结果表明,基于字符形状特征的验证码识别方法可以避开传统方法的部分弊端,同时具有良好的识别效果.     

非线性优化约束变尺度法新进展

讨论了SQP算法与QP-frec算法的研究背景及现状,介绍,它们的具体步骤及其相应的优缺点,构造了一个特殊的仅含等式约束的QP于问题,提出了相应的修正SQP方法,使之仍然具有求解不等式约束二次规划子问题的SQP方法相应的特点.构造一个特殊的线性方程组子问题,提出了相应的修正QP-free方法,减少了每步求斛的子问题个数.     

基于差分光电技术的人血清PSA检测算法研究

血清前列腺特异性抗原(PSA)是前列腺癌早期诊断的重要指标之一.通过采用免疫层析金标试纸和差分光电技术检测PSA浓度的方法,并用分段线性拟合方法分别拟合浓度为0.5～5 、5～50 和50～100 ng/mL范围内PSA浓度和T/C比值的关系.标定结果显示,在5～50 ng/mL范围内PSA浓度和T/C比值的线性相关性较好,其调整决定系数R2为0.924 27,而在该范围之外,它们的线性相关性都较差,不适合用作PSA检测.在浓度为5～50 ng/mL范围内做了11组检测实验,检测值和真实值的相关系数达到了0.910.实验证明,采用差分光电技术检测PSA浓度并用分段线性拟合方法做数据处理是可行的     

主动授权规则实施支持空间特性的RBAC*

为满足安全策略或者角色定义的变化,系统或模型应该提供一种灵活的机制实施支持空间特性的RBAC。引入了OITE（on-if-then-else）主动授权规则实施支持空间特性的RBAC,定义了支持空间特性的RBAC中各基本元素与OITE之间的映射关系。使用OITE作为实施机制,可以在不同粒度上实施带有空间特性角色约束,并且可以将支持空间特性的RBAC应用在多个领域中。最后简要讨论了授权规则如何从支持空间特性的RBAC安全策略中自动产生。     

Decarburization rate of RH refining for ultra low carbon steel

The decarburization behaviors of ultra low carbon steel in a 210-t RH vacuum degasser were investigated under practical operating conditions.According to the apparent decarburization rate constant (KC) calculated by the carbon content in the samples taken from the hot melt in a ladle at an interval of 1-2 min,it is observed that the total decarburization reaction period in RH can be divided into the quick decarburization period and the stagnant decarburization period,which is quite different from the tradit...     

Additive-aided electrochemical deposition of bismuth telluride in a basic electrolyte

A new basic electrolyte with two cationic plating additives,polydiaminourea and polyaminosulfone,was investigated for the electrochemical deposition of the bismuth telluride film on a nickel-plated copper foil.Tellurium starts to deposit at a higher potential(-0.35 V) than bismuth(-0.5 V) in this electrolyte.The tellurium-to-bismuth ratio increases while the deposition potential declines from-1 to-1.25 V, indicating a kinetically quicker bismuth deposition at higher potentials.The as-deposited film featu...     

高等教育与农村经济发展关联分析

本文从高等教育的角度入手,采用关联分析的方法研究了高等教育对农村经济发展的作用。并根据研究结果得出了一些关于发展高等教育和农村经济的建议。     

非典型SVOC结构构式义分析

根据构式语法,典型SVOC结构（即NP2后是名词短语和形容词短语）的构式义是致使变化。而SVOC结构研究中争议较大之处是如何看待和界定NP2后是非限定结构的情况。根据语义分析,这类情况中有些是属于非典型SVOC结构,其意义仍然是致使变化,而另外一些则应视为其它句式,如SVO。不同的学者从不同的角度出发往往得出不同的结论,这种情况从原型范畴理论的角度来看是完全可以理解并且是非常正常的。     

基于PDCA循环工作法实施科学化管装

针对当前我军科学化管装的现状,本文从提高科学化管装的水平入手,综合运用PDCA循环工作法的相关原理,结合当前的实际,就如何提高科学化管装水平进行了探索性的思考,并提出了相关的改进措施。     

Synthesis and characterization of soluble aromatic azopolyamides containing sulfone and ether units

A series of new polyamides 3a–d containing aryl-azo, ether and sulfone groups in the main chain were synthesized from bis[4-(4-aminophenoxy)phenyl sulfone] 1 and several azo aromatic diacyl chlorides 2a–d by the low temperature solution polycondensation technique. FTIR spectroscopy, nuclear magnetic resonance (NMR) and elemental analyses confirmed the structure of these polymers. Owing to the aryl and amide groups in the main chain, these polymers exhibit photochromic properties as well as excellent thermal stabilities. The transition temperatures (T _g) are between 242 and 265 °C, and the char yields at 800 °C in nitrogen atmosphere were above 39%. Based on incorporation of flexible ether linkages and polar sulfone groups, the polyamides show desirable solubility in organic solvents such as DMAc, N,N-dimethylformamide (DMF), N-methyl-2-pyrroidinone (NMP) and dimethylsulfoxide (DMSO). And it is exemplified that polyamide containing 2 and 2′ substitutes performed better solubility. Funded by the National Natural Science Foundation of China (No. 50572081)