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581.
高温下混凝土和钢筋强度的统计分析 总被引:2,自引:0,他引:2
通过对我国有关高温下普通混凝土抗压强度、热轧钢筋屈服强度和预应力钢筋极限强度的大量试验数据进行统计分析,发现在绝大多数情况下他们与各自常温强度之比(相对高温强度)均符合正态分布.给出了不同温度作用下上述3类建筑材料相对高温强度的均值和均方差,分别建立了高温下3类建材的相对高温强度均值和具有95%保证率的分位值随温度的定量变化关系.作为基于可靠度的结构抗火设计基础,积极开展高温下各类建筑材料的力学性能统计分析是十分必要的. 相似文献
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不同晶型锰氧化物去除水中亚甲基蓝染料的研究 总被引:14,自引:1,他引:13
利用溶液法和固态合成法制备α、β、γ和δ晶型粉末二氧化锰,借助等电点测定技术、颗粒计数仪、傅立叶-红外光谱、X射线衍射光谱和原子力显微镜对其性质进行了表征;并通过静态吸附平衡实验考察了上述物质对水溶液中阳离子染料亚甲基蓝的去除效能.结果表明,δ二氧化锰去除染料的能力相对最强,试验条件下染料去除率达99.0%,脱色能力受pH变化的影响也最小;其脱色机理可能是染料中的N原子与二氧化锰表面羟基形成的氢键作用,以及静电吸引的叠加,其中氢键去除占主导地位.其它晶型的二氧化锰只在强酸性时存在表面羟基;故只在强酸性时有良好的脱色能力.pH值是影响去除染料能力的关键因素,脱色能力随pH值的变化规律因晶型而异,体系温度和颗粒分布也对去除能力有一定影响. 相似文献
584.
Moisture distributions in municipal sewage sludge, printing and dyeing sludge and paper mill sludge were experimentally studied based on four different methods, i.e., drying test, thermogravimetric-differential thermal analysis (TG-DTA) test, thermogravimetricdifferential scanning calorimetry (TG-DSC) test and water activity test. The results indicated that the moistures in the mechanically dewatered sludges were interstitial water, surface water and bound water. The interstitial water accounted for more than 50% wet basis (wb) of the total moisture content. The bond strength of sludge moisture increased with decreasing moisture content, especially when the moisture content was lower than 50% wb. Furthermore, the comparison among the four different testing methods was presented.The drying test was advantaged by its ability to quantify free water, interstitial water, surface water and bound water; while TG-DSC test, TG-DTA test and water activity test were capable of determining the bond strength of moisture in sludge. It was found that the results from TG-DSC and TG-DTA test are more persuasive than water activity test. 相似文献
585.
The primary emphasis of this research was to investigate the foundations of phthalate(PAEs) pollutant source researches and then firstly confirmed the concept of the coefficient of volatile strength, namely phthalate total content in per unit mass and unit surface area of pollutant sources. Through surveying and evaluating the coefficient of volatile strength of PAEs from typical plastic products, this research carried out reasonable classification of PAEs pollutant sources into three categories and then investigated the relationship amongst the coefficient of volatile strength as well as other environmental factors and the concentration level of total PAEs in indoor air measured in environment chambers.Research obtained phthalate concentration results under different temperature, humidity,the coefficient of volatile strength and the closed time through the chamber experiment. In addition, this study further explored the correlation and ratio of influencing factors that affect the concentration level of total PAEs in environment chambers, including environmental factors, the coefficient of volatile strengths of PAEs and contents of total PAEs in plastic products. The research created an improved database system of phthalate the coefficient of volatile strengths of each type of plastic goods, and tentatively revealed that the volatile patterns of PAEs from different typical plastic goods, finally confirmed that the coefficient of volatile strengths of PAEs is a major factor that affects the indoor air total PAEs concentration, which laid a solid foundation for further establishing the volatile equation of PAEs from plastic products. 相似文献
586.
Wei-Eng Thung Soon-An Ong Li-Ngee Ho Yee-Shian Wong Fahmi Ridwan Yoong-Ling Oon Yoong-Sin Oon Harvinder Kaur Lehl 《环境科学学报(英文版)》2018,30(4):295-300
This study demonstrated the potential of single chamber up-flow membrane-less microbial fuel cell(UFML-MFC) in wastewater treatment and power generation. The purpose of this study was to evaluate and enhance the performance under different operational conditions which affect the chemical oxygen demand(COD) reduction and power generation,including the increase of KCl concentration(MFC1) and COD concentration(MFC2). The results showed that the increase of KCl concentration is an important factor in up-flow membrane-less MFC to enhance the ease of electron transfer from anode to cathode. The increase of COD concentration in MFC2 could led to the drop of voltage output due to the prompt of biofilm growth in MFC2 cathode which could increase the internal resistance. It also showed that the COD concentration is a vital issue in up-flow membrane-less MFC.Despite the COD reduction was up to 96%, the power output remained constrained. 相似文献
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589.
预测结垢趋势是污水回注中的一项重要工作,通常都要计算离子强度,而离子强度的计算量很大,因此提出了一种替代的估算方法———矿化度法。由于矿化度的测定较为容易,计算简便,建立矿化度和离子强度之间的一元线性关系,使计算得以大大简化。通过中原油田的实例详细说明了一元线性关系的建立方法及判定是否适用的标准,并提出:不同水质情况应分别建立各自的一元线性回归方程。 相似文献
590.
高强度开发下的上海农业环境问题与对策 总被引:6,自引:0,他引:6
文章指出高强度开发下上海市郊主要的农业污染问题,并分析了污染形成的原因,提出了符合可持续发展战略的污染探讨对策。 相似文献