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241.
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壳聚糖复合絮凝剂处理造纸废水的实验研究 总被引:3,自引:0,他引:3
研究并考察了壳聚糖复合絮凝剂对造纸污水中COD和SS的絮凝效果,结果表明,当复合絮凝剂的配方和处理条件为:聚合硫酸铁(PFS)60 mg/L聚丙烯酰胺(PAM)2 mg/L壳聚糖(CTS)0.4 mg/L,pH为7.5时,其絮凝效果最佳,此时它对水中COD与SS的去除率分别达到57.4%和97.6%, 与传统絮凝剂PAC/PAM相比,COD与SS的去除率分别提高了10.1%和5.2%,药剂成本下降了21.1%,具有明显的经济效益与环境效益。 相似文献
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地冲击荷载作用下双层结构磁流变阻尼器隔震效果的数值模拟 总被引:1,自引:0,他引:1
在抗爆结构中,一般采用单层隔震系统进行隔震,目前单层隔震系统的最大隔震率可以达到90%以上,但在加速度峰值很高的冲击荷载作用下,隔震后的结构响应加速度仍然很大。鉴于这种情况,本文对加入磁流变阻尼器(MRD)的双层隔震系统进行了研究。针对抗爆结构的两种典型荷载,采用改进Bouc-Wen模型和模糊控制方法,利用Matlab Simulink对双层隔震系统进行了数值模拟,计算了不同荷载作用下,不同隔震系统的加速度、位移及结构的振动剂量值(VDV)的响应,并与结构采用单层隔震系统的结果进行了对比。结果表明,与单层隔震系统相比,带有磁流变阻尼器的双层隔震系统没有太多的优越性。 相似文献
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The main focus of this study was to evaluate long term effects of cadmium on forearm bone mineral density after stopping ingestion of cadmium-polluted rice for 10 years in a Chinese population. A total of 532 persons (338 women and 194 men), living in control, moderately and heavily polluted areas, were included in this study. The residents living in the polluted area ceased ingesting cadmium-polluted rice in 1996. All participants were require to answer a questionnaire and the bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of cadmium in urine (UCd) and blood (BCd).The BMD of subjects living in the heavily polluted area was significantly lower than that of those living in control area in both men and women (p < 0.01). For the people living in the moderately polluted area, only the women's BMD was greatly lower compared to that in the control area (p < 0.05). The BMD declined with the increasing BCd and UCd in both sexes, especially in the highest level (BCd > 5 µg/L, UCd > 10 µg/g crea) groups (p < 0.01). It was found that there were significant differences in the prevalence of osteoporosis among the different areas (χ2 = 13.046, p = 0.0003) and different UCd groups (χ2 = 4.511, p = 0.0337) in women, but not in men (χ2 = 0.962, p = 0.3268; χ2 = 1.906, p = 0.1675). But a significant difference exists in the prevalence of osteoporosis among different BCd groups in both genders (χ2 = 9.304, p = 0.00229, in women; χ2 = 4603, p = 0.0319, in men). This study suggested that cadmium could play a long-term role on bone and more attention should be paid to cadmium effects on bone metabolism after reduction of exposure. 相似文献
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Fu-Sheng Liu Zhuo Li Shi-Tao Yu Xiao Cui Cong-Xia Xie Xiao-Ping Ge 《Journal of Polymers and the Environment》2009,17(3):208-211
Alkali-catalyzed methanolysis and hydrolysis of polycarbonate (PC) in a solvent in which PC can substantially dissolve such
as N-methyl-2-pyrrolidone, 1,4-dioxane, tetrahydrofuran and so on were studied. Reaction conditions were optimized for the purpose
of recycling PC in the form of bisphenol A and carbon carbonate. The results showed that both the methanolysis and hydrolysis
of PC could take place under moderate conditions. Under the conditions of reaction temperature 40 °C, m(PC):m(MeOH) = 1:1,
m(PC):m(NaOH) = 50:1, reaction time 35 min and using tetrahydrofuran as solvent, the methanolysis conversion of PC was almost
100% and the yield of bisphenol A was over 95%. Moreover, under the conditions of reaction temperature 100 °C, m(PC):m(H2O) = 1:0.7, m(PC):m(NaOH) = 10:1, reaction time 8 h and using 1,4-dioxane as solvent, the hydrolysis conversion of PC was
almost 100% and the yield of bisphenol A was over 94%. 相似文献
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可靠性理论在公共安全领域的应用研究 总被引:2,自引:0,他引:2
对公共安全体系从系统可靠性的视角,综合运用可靠性方面的知识,构建公共安全系统混联模型;进而将可靠性分配理论与故障树分析方法相结合,根据系统安全目标的要求,确定混联系统的第一层次各单元事件的可靠性目标值,对构成各单元的各个下属单元采取最小工作量可靠度分配方法,从而建立系统中各单元可靠度再分配量化模型。通过建筑物火灾引起人员伤亡事故实例,详述系统各单元可靠性分配的计算过程。研究表明,可靠性理论可以成功地应用到公共安全领域;使系统在给定的目标值条件下达到系统的安全性优化,实现了公共安全保障效能,减小灾害损失。 相似文献