Vibration testing based on impulse response excited by pulsed-laser ablation: Measurement of frequency response function with detection-free input

2012 ◽  
Vol 331 (6) ◽  
pp. 1355-1365 ◽  
Author(s):  
Naoki Hosoya ◽  
Itsuro Kajiwara ◽  
Takahiko Hosokawa
Keyword(s):  
Laser Ablation ◽  
Frequency Response ◽  
Impulse Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Vibration Testing

Modal identification for superstructure using virtual impulse response

2019 ◽  
Vol 22 (16) ◽  
pp. 3503-3511 ◽  
Author(s):  
Chun-Xu Qu ◽  
Ting-Hua Yi ◽  
Hong-Nan Li
Keyword(s):  
Frequency Response ◽  
Impulse Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Single Point ◽  
Modal Identification ◽  
Eigensystem Realization Algorithm ◽  
Power Spectral ◽  
Practical Engineering ◽  
Spectral Density Functions

In civil engineering, structural modes are identified with the assumption of stationary white noise, which cannot be satisfied in practical engineering. This article proposes a new method, which contains the virtual impulse response and eigensystem realization algorithm. The formulation of virtual impulse response is derived from the inverse Fourier transform of the ratio of the cross-power to auto-power spectral density functions of the measurement responses, which is based on the concept of frequency response function. During the formulation derivation, a single point excitation is only considered. Frequency response function would not change with different excitations and responses, which means that the excitation cannot influence frequency response function. The impulse response is pointed out to only represent the behavior of superstructure. After obtaining impulse responses, eigensystem realization algorithm is then performed to identify the modes of superstructure. The proposed method is validated by a numerical example. The results show that virtual impulse response can have much better free decayed behavior than natural excitation technique and identify very precise modal parameters for superstructure.

Observations on the growth of YBa2Cu3O7-δ thin films on MgO by pulsed-laser ablation

1991 ◽  
Vol 49 ◽  
pp. 1068-1069
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Laser Ablation ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Laser Ablation Process ◽  
Deposition Parameters

Pulsed-laser ablation has been widely used to produce high-quality thin films of YBa2Cu3O7-δ on a range of substrate materials. The nonequilibrium nature of the process allows congruent deposition of oxides with complex stoichiometrics. In the high power density regime produced by the UV excimer lasers the ablated species includes a mixture of neutral atoms, molecules and ions. All these species play an important role in thin-film deposition. However, changes in the deposition parameters have been shown to affect the microstructure of thin YBa2Cu3O7-δ films. The formation of metastable configurations is possible because at the low substrate temperatures used, only shortrange rearrangement on the substrate surface can occur. The parameters associated directly with the laser ablation process, those determining the nature of the process, e g. thermal or nonthermal volatilization, have been classified as ‘primary parameters'. Other parameters may also affect the microstructure of the thin film. In this paper, the effects of these ‘secondary parameters' on the microstructure of YBa2Cu3O7-δ films will be discussed. Examples of 'secondary parameters' include the substrate temperature and the oxygen partial pressure during deposition.

scholarly journals Doping nanoparticles using pulsed laser ablation in a liquid containing the doping agent

2019 ◽  
Vol 1 (10) ◽  
pp. 3963-3972 ◽  
Author(s):  
Arsène Chemin ◽  
Julien Lam ◽  
Gaétan Laurens ◽  
Florian Trichard ◽  
Vincent Motto-Ros ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Doping Agent ◽  
Laser Ablation In Liquids ◽  
Dope Nanoparticles

While doping is crucial for numerous technological applications, its control remains difficult especially when the material is reduced down to the nanometric scale. We suggest a new way to dope nanoparticles using laser ablation in liquids.

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