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钢结构人行天桥由于其自重轻,因此对外部激励的振动效应更加明显。在一定的条件下,桥上的行人会由于结构振动而产生不舒适感或不安全感。然而,目前我国有关设计规范中,没有给出人行天桥的振动舒适度评价指标。参考国外相关规范中关于人行天桥舒适度的评价标准,并结合工程实例,论述相关评价标准在人行天桥减振加固设计中的应用。 相似文献
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This paper describes the fabrication, characterization and properties of a novel hybrid poly(ethylene glycol) (PEG) based hydrogel via in situ polymerization. The hybrid hydrogel was fabricated by free-radical redox polymerization using ammonium persulfate (APS) and N, N, N??, N??-tetramethylethylenediamine (TEMED) as initiators and N, N??-methylene bisacrylamide (BIS) as cross-linker at 60°C. To create a hybrid hydrogel, 0.2% (mass fraction) of MgAl layered double hydroxide (LDH) was added to the aqueous solution by ultrasonic dispersion. The physicochemical properties of hybrid hydrogel under vacuum freeze-drying processing were characterized by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM), while swelling kinetics and gel content were calculated. Swelling degree in distilled water varied from 94%?C125% with a gel mass fraction of 83%?C91%. SEM images showed that the micron pore size of hydrogel could be adjusted within the range of several micrometers by changing the cross-linker mass fraction from 2% to 10% (based on glycol). The results showed that the hybrid hydrogels exhibited excellent physicochemical behavior and might be a promising material for applications in tissue engineering and drug delivery. 相似文献
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程江 《石家庄铁道学院学报》2010,23(3):101-105
研究了共因失效修理工多重休假的两相同部件串联系统的可靠性,在假定部件的失效分布服从指数分布,修理工修理时间和休假时间均服从一般连续型分布的条件下,利用补充变量法,得到了该系统的瞬时可用度和稳态可用度、系统的可靠度、系统的瞬时和稳态故障频度等重要可靠性指标。 相似文献
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