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Anders Brandt Marta Berardengo Stefano Manzoni Marcello Vanali Alfredo Cigada 《声与振动》2018,52(3):18-22
Methods for scaling mode shapes determined by operational modal analysis (OMA) have been extensively investigated in the last years. A recent addition to the range of methods for scaling OMA mode shapes is the so-called OMAH technique, which is based on exciting the structure by harmonic forces applied by an actuator. By applying harmonic forces in at least one degree-of-freedom (DOF), and measuring the response in at least one response DOF, while using at least as many frequencies as the number of mode shapes to be scaled, the mode shape scaling (modal mass) of all modes of interest may be determined. In previous publications on the method the authors have proven that the technique is easy and robust to apply to both small scale and large scale structures. Also, it has been shown that the technique is capable of scaling highly coupled modes by using an extended multiple reference formulation. The present paper summarizes the theory of the OMAH method and gives recommendations of how to implement the method for best results. It is pointed out, as has been shown in previous papers, that the accuracy of the mode scaling is increased by using more than one response DOF, and by selecting DOFs with high mode shape coefficients. To determine the harmonic force and responses, it is recommended to use the three-parameter sine fit method. It is shown that by using this method, the measurement time can be kept short by using high sampling frequency and bandpass filtering whereas spectrum based methods require long measurement times. This means that even for structures with low natural frequencies, the extra measurement time for scaling the mode shapes can be kept relatively short. 相似文献
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文章介绍了5G通信中的载波调制和编码技术,包括二相相移键控、四相相移键控、正交振幅调制,低密度奇偶校验码和极化码等,多址技术包括正交多址和非正交多址,说明其基本原理和特点及应用场合。 相似文献
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文章介绍了基于IMS的PoC业务的特性与市场背景,通过与传统数字集群、移动Fetion以及Skype等业务比较,对PoC业务的客户体验、通信运营、技术支撑等业务开展的关键问题进行了分析和阐述。只有在业务开展中突破其中的瓶颈,PoC业务才能真正成为3G网络中的杀手级应用。 相似文献
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目前的网络多媒体业务越来越强调交互,强调用户参与,而多屏业务(手机屏,电脑屏,IPTV电视屏)由于跨越3种异构网络(移动通信网、有线以太网、广电网/电信IPTV网),涉及3种终端,交互在多屏业务中的作用就更加突出了。因此,我们必须给出一套跨越3种异构网络进行交互的方案,能够使用户尽情享受眩彩多屏业务。OMA国际标准中已经规定了交互机制以及异构网络下的设备管理机制,本文就利用OMA国际标准中的交互机制以及设备管理机制构建了一套智能交互式多屏解决方案。 相似文献
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文章首先介绍了IMS提供的业务应用支持能力,重点描述了3GPP IMS的业务架构和OMA定义的OSE架构,并对两者之间的关系进行了分析,最后介绍了基于IMS能力的典型业务实现和相关协议,以及相关标准的进展情况. 相似文献
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用二维OMA系统对He-Ne激光管的侧光辐射进行了空间分辨光谱测量,得到了He-Ne激光器可见激光辐射的小讯号增益及增益饱和的空间分布,研究了增益饱和性质,推算了活体积的大小和饱和光强等参量。 相似文献
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以十八碳醇甲基丙烯酸酯为单体、乙二醇二甲基丙烯酸酯为交联剂,采用原位聚合法合成了一种新型毛细管开管柱固定相,优化了毛细管开管柱的制备参数。柱内表面的电镜图像显示其具有多孔皱褶、质地均匀的结构特征。将其应用于甲苯、乙苯、丙苯、丁苯、戊苯和己苯的分离试验中,6种化合物达到了完全分离,出峰顺序与它们的疏水性一致,表明该柱有明显的疏水色谱作用。在10 mmol/L磷酸盐(pH 8.5,含50%(v/v)乙腈)流动相、16 kV电压下,该开管柱成功地分离了4种抗癫痫类药物,柱效范围为35300~49800 塔板/m,与空柱管相比分离效果明显提高。结果表明通过本实验的原位聚合法可制备具有反相色谱作用的有机基质碳十八开管毛细管电色谱柱。 相似文献