Definitions of physical quantities for fundamental frequency and time metrology - random instabilities 基本頻率和時間計量學(xué)用物理量定義.隨機(jī)不穩(wěn)定性
Test method for moduli of elasticity and fundamental frequencies of carbon and graphite materials by sonic resonance 用音響共振法測定炭精和石墨的彈性模量與基本頻率的試驗(yàn)方法
Because damage and reinforcement change the mass and stiffness of building , they will change frequency . so , what is the regularity of this change and how to apply the regularity in practical work are a problem deserving of public attention . in this paper . regarding the typical steel industry building as the object . applying the dynamic stiffness method to make simulation analysis , the author firstly gets the regularity of frequency change 如何在工程實(shí)際中主動應(yīng)用這些規(guī)律?都是值得研究的問題。本文以典型的鋼結(jié)構(gòu)單層廠房為研究對象,應(yīng)用動力剛度法進(jìn)行計算機(jī)模擬,系統(tǒng)研究損傷和加固對結(jié)構(gòu)基本頻率的影響,探索出一些規(guī)律;并用貢獻(xiàn)理論解釋了這些規(guī)律。
It discusses some kinds of basic frequency synthesis technology such as direct , phase - lock , digital and direct digital frequency synthesis , then give the performance index of the frequency synthesis , and discusses the digital frequency synthesis technology in detail 討論了直接式頻率技術(shù)、鎖相式頻率合成技術(shù)、數(shù)字式頻率合成技術(shù)、直接數(shù)字頻率合成技術(shù)等幾種基本頻率合成技術(shù),給出的衡量頻率合成技術(shù)的各種性能指標(biāo),并對全數(shù)字頻率合成技術(shù)作了較詳細(xì)的討論。