基于组合赋权的铁路时间同步网云评估模型及应用

针对模糊综合评价法在铁路时间同步网可靠性评价中的不足,提出了基于组合赋权的铁路时间同步网云评估模型。首先,根据铁路时间同步网的功能结构,构建系统综合能力模型,建立其对应的功能硬件层次结构,从而选取影响铁路时间同步网可靠性的主要评价指标。然后,利用标度扩展AHP法和熵权法分别计算铁路时间同步网各评价指标的主客观权重,并且通过引入欧几里德距离函数计算差异系数,使主、客观权重之间的偏离程度与权重系数一致,从而获得各指标合理的综合权重。最后,计算各指标相对值,并且利用云模型表示,进行云计算得到综合指标云,将该综合指标云与可靠性评价集的云模型进行相似度度量,得到铁路时间同步网综合可靠性评价结果。结果表明,基于组合赋权的铁路时间同步网云评估模型能够实现对铁路时间同步网综合可靠性的评价。     

振动纤维栅除尘器中单纤维振动特性的研究

在振动纤维栅除尘器中,气流绕流纤维时旋涡脱落频率（Re＞40）与纤维的固有频率相近,发生同步效应,使振动纤维栅中的纤维产生共振响应。本根据弦的波动方程,运用振型叠加法计算纤维的振动响应,并与实验结果进行了比较。结果表明,纤维的共振幅响应与固有频率、阻尼比、旋涡脱落频率（Sr数）、流体的作用力有关,并给出了振幅表达式。     

High resolution chromosomes from first trimester trophoblast cultures

A simple method for obtaining prometaphase chromosomes from cultured first trimester cells involves the addition of BrdU and FdU 11 h before harvest and ethidium bromide 1.5 h before harvest. High resolution R-banding is obtained by acridine orange staining.     

Social synchronization of the activity rhythms of honeybees within a colony

Colonies and isolated bees of the Cape honeybee, Apis mellifera capensis Esch., were observed for evidence of circadian rhythmicity under constant conditions. It was found that colonies develop free-running activity rhythms in self-selected light-dark cycles, which are slightly shorter than 24 h. The periods of the activity rhythms of individual isolated bees were longer than 24 h in self-selected light-dark and constant light, while they were shorter than 24 h in constant darkness. A greater variability in period was found in the isolated bees than in the colonies. When the rhythms of colonies and individual bees from these colonies were measured simultaneously, the activities of the isolated bees drifted with respect to that of the colonies, their period being either longer or shorter than that of their own colony. After 12 days of isolation of individual bees from their colony, all coincidence between the phases of the two rhythms was lost. We conclude that the periods of common activity and common rest of the bees within a colony result from a mutual (social) synchronization of the rhythms of the individual bees.