叠加法在定解问题求解中的应用

叠加法是一种简单而普遍的数学方法，但它在求解定解问题中却起着极其重要的作用，从最一般的但也比较复杂的振动问题着手分析叠加法在定解问题求解中的作用。     

一种按指标分层决策矩阵的加权归-算法与实现

讨论了按指标分层决策矩阵的多指标综合评价问题,描述了按指标分层的决策矩阵的求解算法,并采用ＶｉｓｕａｌＦｏｘｐｒｏ数据库语言编程实现。     

A novel color image encryption algorithm based on DNA sequence operation and hyper-chaotic system

A new color image encryption algorithm based on DNA (Deoxyribonucleic acid) sequence addition operation is presented. Firstly, three DNA sequence matrices are obtained by encoding the original color image which can be converted into three matrices R, G and B. Secondly, we use the chaotic sequences generated by Chen's hyper-chaotic maps to scramble the locations of elements from three DNA sequence matrices, and then divide three DNA sequence matrices into some equal blocks respectively. Thirdly, we add these blocks by using DNA sequence addition operation and Chen's hyper-chaotic maps. At last, by decoding the DNA sequence matrices and recombining the three channels R, G and B, we get the encrypted color image. The simulation results and security analysis show that our algorithm not only has good encryption effect, but also has the ability of resisting exhaustive attack, statistical attack and differential attack.     

反应合成TiB_2工艺研究

本文就TiB2粉末的反应合成工艺进行初步探讨,采用XRD分析技术对在不同温度下的试样进行相结构组成分析;由气相色谱法测定粉末的C和O2等杂质;通过电子探针对粉末进行扫描形貌（SEM）观察．实验表明：原料配碳（Cm）和合成温度（T）是影响粉末质量的关键因素．     

辐射事故中确定性健康危害的剂量学评价方法(Ⅰ)

确定性效应是辐射事故中主要关心的健康危害。辐射事故照射,除大剂量急性照射情况外,更多的还有受照延续时间不等、照射水平不一的多次受照情况,甚至尚有数天内连续受照的。本文从辐射效应的“线性-平方”模型出发,借助目前已经掌握的确定性效应的剂量阈值,针对剂量的不同时间分布,集中探讨低LET辐射事故中评价确定性健康危害的剂量学方法。引用了分割照射和延续照射的外推剂量概念,提出了外推剂量可加原理和等外推剂量等效应原理。     

Versatile 2-amino-4-substituted-1,3-thiazoles: synthesis and reactions

Syntheses and reactions of 2-amino-4-substituted-1,3-thiazoles are reviewed in a formal way. The title compounds are most easily accessible by various approaches, and even waste-free solid-state procedures have been developed. The substitution in 4-position has synthetic reasons and therefore most interest accumulates around these derivatives of 2-aminothiazole. The high reactivity of both the amino group and the positions 3 and 5 of the 1,3-thiazole ring are used for numerous syntheses in a comprehensive way. The reactions are subdivided in groups that cover reactions at the amino substituent without touching the thiazole ring, reactions which involve both nitrogens in the formal amidine system to give thiazolo-pyrimidinones and -imidazoles as well as more involved polycondensed N,S-heterocycles with multiple possibilities for substituents, and substitution reactions at the 5-position of the thiazole ring. Most of the imaginable reaction types have been successfully applied and used, as many of the synthesized compounds exhibit interesting biological activity in various fields.     

Novel allylic phosphonium salts in free radical accelerated cationic polymerization

In the present study, the synthesis and evaluation of novel allylic phosphonium salts as addition fragmentation agents in combination of conventional (photo-/thermal) free radical source for cationic polymerization are described. The amide based allylic phosphonium salts, namely 2-(N, N-dimethylcaboxy-propenyl) triphenylphosphonium hexafluoroantimonate (DMTPH) and 2-(morpholinocarboxy-propenyl) triphenyl phosphonium hexafluoroantimonate (MTPH) were synthesized and characterized. The thermal and photo-latency of these salts was examined with and without free radical sources in bulk polymerization of cyclohexene oxide (CHO) salts at 70 °C and λ > 290 nm irradiation, respectively. In presence of thermal free radical source, the order of activity was observed as PAT > BPO > AIBN. The order of activity of free radical sources on photopolymerization was found to be benzoin > benzophenone > TMDPO. In addition, photopolymerization of other cationically polymerizable monomers (such as n-butyl vinyl ether, isobutyl vinyl ether, N-vinyl carbazole and glycidyl phenyl ether) was also examined at λ > 290 nm irradiation. It is concluded that the rate of cationic polymerization can be accelerated using novel phosphonium salts with combination of free radical sources, by both thermal and photochemical mode.     

苯乙烯和四氯化碳合成肉桂酸

通过浸渍法制备了CuCl/γ-Al₂O₃ 和CuO/γ-Al₂O₃ 催化剂。在CuCl/γ-Al₂O₃ 和CuO/γ-Al₂O₃ 分别与吡啶组成的催化体系中, 苯乙烯和四氯化碳发生加成反应, 生成1,3 , 3, 3-四氯丙基苯(I)。当CuCl/γ-Al₂O₃ 和CuO/γ-Al₂O₃ 最佳活化温度分别为650 ℃和750 ℃, CuCl 和CuO 的负载质量分数分别为20.0 %和10 .0%时,1, 3, 3 , 3-四氯丙基苯(I)的收率分别为62.8%和70.3%。在对甲苯磺酸-硫酸、FeCl₃·6H₂O、Fe₂(SO₄)₃·7H₂O、ZnCl₂ 和硫酸锌等酸性催化剂存在的情况下, 1, 3 , 3, 3 -四氯丙基苯(I)在醋酸溶液中水解生成肉桂酸(II), 收率分别为87.0 %、48.0%、84 .4%、77 .4%和87 .1%。1, 3 , 3, 3 -四氯丙基苯(I)和肉桂酸(II)的纯度为96 .0%～ 99.0 %。     

模2n加法最佳线性逼近关系研究

该文研究了模2n加法运算的最佳线性逼近问题。利用权位分量函数的线性逼近关系,该文首先给出了模2n加法最佳线性逼近相关值的计算公式。其次通过递归构造得到了模2n加法最佳线性逼近集的生成方法。该文的研究从理论上更清楚地刻画了二元模2n加法最佳线性逼近的内在规律,有助于更好地利用该线性逼近关系实现对实际密码算法的有效分析。     

基于随机加法链的高级加密标准抗侧信道攻击对策

侧信道攻击已经对高级加密标准(AES)的硬件安全造成严重威胁,如何抵御侧信道攻击成为目前亟待解决的问题。字节替换操作作为AES算法中唯一的非线性操作,提高其安全性对整个加密算法有重要意义。该文提出一种基于随机加法链的AES抗侧信道攻击对策,该对策用随机加法链代替之前固定的加法链来实现有限域GF(2⁸)上的乘法求逆操作,在此基础上研究随机加法链对算法安全性和有效性方面的影响。实验表明,所提随机加法链算法比之前固定的加法链算法在抵御侧信道攻击上更加安全、有效。