scholarly journals Measurement of power spectral density of broad-spectrum visible light with heterodyne near field scattering and its scalability to betatron radiation

2015 ◽  
Vol 23 (26) ◽  
pp. 32888 ◽  
Author(s):  
M. Siano ◽  
B. Paroli ◽  
E. Chiadroni ◽  
M. Ferrario ◽  
M. A. C. Potenza
2012 ◽  
Vol 06 (02) ◽  
pp. 1250013 ◽  
Author(s):  
A. A. FATEMI ◽  
A. BAGHERI ◽  
G. GHODRATI AMIRI ◽  
M. GHAFORY-ASHTIANY

The sets of records developed for the SAC Steel Project are classified according to the level of seismic hazard and specific geographic region, and have been used extensively for structural response and seismic hazard analyses. This study presents a parametric analysis of these record data sets for generation of uniform hazard earthquake and near-field records. The record parameters define far-field characteristics such as power spectral density and envelope function, and near-field effects such as acceleration pulse, power spectral density and envelope function. The proposed method for generation of near-field records uses the decomposing capabilities of wavelet transform on earthquake records. A set of uniform hazard earthquake accelerograms and near-field ground motions is generated based on the record parameters. The generated uniform hazard earthquake accelerograms representing a uniform level of seismic hazard for a particular geographic region involves seismic hazard studies, calibrated attenuation relationships, and local site amplification models. In order to assess the reliability and efficiency of the presented method, the statistical response spectra obtained from the generated accelerograms have been compared with those from the actual records. The obtained results showed that there is a good compatibility between the response spectra of the generated and actual records in the most of the frequencies.


2017 ◽  
Vol 25 (22) ◽  
pp. 26591 ◽  
Author(s):  
Shenzhen Wang ◽  
Qiang Yuan ◽  
Fa Zeng ◽  
Xin Zhang ◽  
Junpu Zhao ◽  
...  

2009 ◽  
Vol 2 (1) ◽  
pp. 40-47
Author(s):  
Montasser Tahat ◽  
Hussien Al-Wedyan ◽  
Kudret Demirli ◽  
Saad Mutasher

Author(s):  
Benjamin Yen ◽  
Yusuke Hioka

Abstract A method to locate sound sources using an audio recording system mounted on an unmanned aerial vehicle (UAV) is proposed. The method introduces extension algorithms to apply on top of a baseline approach, which performs localisation by estimating the peak signal-to-noise ratio (SNR) response in the time-frequency and angular spectra with the time difference of arrival information. The proposed extensions include a noise reduction and a post-processing algorithm to address the challenges in a UAV setting. The noise reduction algorithm reduces influences of UAV rotor noise on localisation performance, by scaling the SNR response using power spectral density of the UAV rotor noise, estimated using a denoising autoencoder. For the source tracking problem, an angular spectral range restricted peak search and link post-processing algorithm is also proposed to filter out incorrect location estimates along the localisation path. Experimental results show the proposed extensions yielded improvements in locating the target sound source correctly, with a 0.0064–0.175 decrease in mean haversine distance error across various UAV operating scenarios. The proposed method also shows a reduction in unexpected location estimations, with a 0.0037–0.185 decrease in the 0.75 quartile haversine distance error.


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