scholarly journals High-frequency source localization in the Strait of Sicily

2002 ◽  
Author(s):  
C. Soares ◽  
M. Siderius ◽  
S.M. Jesus
Keyword(s):  
Source Localization ◽  
High Frequency ◽  
Strait Of Sicily ◽  
Frequency Source

scholarly journals An Improved Algorithm for Noise Source Localization Based on Equivalent Source Method

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Zhongming Xu ◽  
Qinghua Wang ◽  
Yansong He ◽  
Zhifei Zhang ◽  
Shu Li ◽  
...  
Keyword(s):  
Source Localization ◽  
High Frequency ◽  
Noise Source ◽  
Near Field ◽  
Low Frequency ◽  
Equivalent Source ◽  
Source Method ◽  
Functional Equivalent ◽  
Acoustical Holography ◽  
Equivalent Source Method

Near-field acoustical holography (NAH) based on the equivalent source method (ESM) is an efficient method applied for noise source identification. Asl2-norm-based regularization cannot produce a satisfactory solution of the ill-conditioned problem in high frequency, the conventional ESM is restricted to relatively low frequency, and the resolution of conventional ESM in middle to high frequency remains a limitation open to investigation. This article presents an algorithm known as improved functional equivalent source method (IFESM), designed to enhance the resolution of conventional ESM. This method is developed in the framework of wideband acoustical holography (WBH) combining with functional beamforming (FB). Through numerical simulations, it is proved that the proposed method can localize noise with higher resolution compared with WBH and conventional ESM, and the ghosts on noise source map can be suppressed effectively. The validity and the feasibility of the proposed method are manifested by experiments including single-source and coherent-source localization.

scholarly journals Unveiling the high-frequency radio source population with the AT20G survey

2013 ◽  
Vol 9 (S304) ◽  
pp. 205-208
Author(s):  
Elizabeth K. Mahony
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
High Frequency ◽  
Gamma Ray ◽  
Low Frequency ◽  
Radio Sources ◽  
Source Population ◽  
Frequency Source ◽  
Galaxy Population ◽  
5 Ghz

AbstractUntil recently, the radio sky above 5 GHz was relatively unexplored. This has changed with the completion of the Australia Telescope 20 GHz survey (AT20G; Murphy et al., 2010); a blind survey of the southern sky down to a limiting flux density of 40 mJy. The AT20G survey provides by far the largest and most complete sample of high-frequency radio sources yet obtained, offering new insights into the nature of the high-frequency active galaxy population. Whilst the radio data provides a unique sample of objects, these data alone are insufficient to completely constrain models of radio source properties and the evolution of radio galaxies. Complementary multiwavelength data is vital in understanding the physical properties of the central black hole.In this talk I will provide a brief overview of the AT20G survey, followed by a discussion of the multiwavelength properties of the high-frequency source population. In particular, I will focus on the optical properties of AT20G sources, which are very different to those of a low-frequency selected sample, along with the gamma-ray properties where we find a correlation between high-frequency radio flux density and gamma-ray flux density. By studying the multiwavelength properties of a large sample of high-frequency radio sources we gain a unique perspective on the inner dynamics of some of the most active AGN.

scholarly journals Imaging zero-offset 3-D P-cable data with CRS method

2019 ◽  
Vol 219 (3) ◽  
pp. 1876-1884 ◽  
Author(s):  
M Glöckner ◽  
J Walda ◽  
S Dell ◽  
D Gajewski ◽  
J Karstens ◽  
...  
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Kinematic Wave ◽  
Data Set ◽  
Time Migration ◽  
Seismic Acquisition ◽  
Common Reflection Surface ◽  
Frequency Source ◽  
Zero Offset ◽  
Migration Velocities

SUMMARY Standard seismic acquisition and processing require appropriate source–receiver offsets. P-cable technology represents the opposite, namely, very short source–receiver offsets at the price of increased spatial and lateral resolution with a high-frequency source. To use this advantage, a processing flow excluding offset information is required. This aim can be achieved with a processing tuned to diffractions because point diffractions scatter the same information in the offset and midpoint direction. Usually, diffractions are small amplitude events and a careful diffraction separation is required as a first step. We suggest the strategy to use a multiparameter stacking operator, for example, common-reflection surface, and stack along the midpoint direction. The obtained kinematic wave-front attributes are used to calculate time-migration velocities. A diffractivity map serves as a filter to refine the velocities. This strategy is applied to a 3-D P-cable data set to obtain a time-migrated image.

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