Photodegradation of methyl orange from wastewater on TiO2/SnS combined powders

The photodegradation of an aqueous solution of methyl orange by the TiO₂/SnS powders was studied in different ratios of SnS against TiO₂. The effects of the initial pH value and light resource were investigated. The SnS extends the light absorption edge of the TiO₂ to ~940 nm of the SnS (1.32 eV). The results indicated that the optimal SnS proportion for the maximum degradation efficiency increased in relation to a decrease in the initial pH in both sunlight and visible light, and decreased when changing from visible light to sunlight. The pure TiO₂ powder had maximum efficiency in conditions of pH 9 and visible light irradiation or in conditions of pH 7 and sunlight irradiation. In visible light, the degradation efficiency on the powders containing the SnS was larger than that on the pure TiO₂ powder in a range of pH 3–7. The maximum efficiency in visible light was found to be in conditions of pH 5 and TiO₂:SnS = 3:2 and 2:3, beyond which the efficiency decreased. The efficiency was, overall, larger in sunlight than in visible light. The mechanism of the effects of pH and light resource was discussed in view of the surface charge of the catalysts.     

带干扰的保费随机收取的双险种风险模型

推广了已有文献中提出的带干扰的双险种复合负二项风险模型,让保费收取次数服从负二项分布,两类险种的索赔也服从负二项分布,得到了带干扰的保费随机收取的双险种风险模型,给出了破产概率的一般表达式和上界．     

反应速率和反应进度的辩证关系——以甲基丙烯酸甲酯自由基聚合为例

化学反应速率与化学反应进度是非常相似的概念和知识点,同时又密切相关。在宏观层面或者说表象层面上看,都描述了过程变化的程度,但二者确具有完全不同的性质,一个是动力学量、一个是热力学量;一个是微观性质、一个是宏观性质。通过甲基丙烯酸甲酯自由基聚合过程的分析,深入讨论和揭示反应速率与反应进度的内涵、意义,明确二者的辩证本质关系,以使学生进一步巩固如何提高聚合物产率、分子量等方面的理论知识,提高学生的学习能力,同时也促进在今后工作中的实践能力和创新能力的提高具有重要的意义。     

Hilbert空间中C_o-半群族指数稳定性

主要讨论了Hilbert空间中Co-半群族Th(t)指数稳定问题,证明了满足||Th(t)||≤Meσt(M,σ与h无关)的半群族Th(t)指数稳定与弱Lp-稳定是等价的,并且给出了另外的三个判定Th(t)指数稳定的等价条件.     

动态DEA方法及其在投资环境风险评估中的应用

基于DEA理论,提出了一种动态评价的模型,实例验证表明该模型具有方法简单有效、结果可靠等特点,同时也为其它事物的动态评价开辟了一条新的途径.