scholarly journals Ensemble Averaging and Resolution Enhancement of Digital Radar and Sonar Signals

10.5772/39409 ◽  
2009 ◽  
Author(s):  
Leiv yehaug ◽  
Roar Skartlie
Keyword(s):  
Resolution Enhancement ◽  
Ensemble Averaging

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

Image resolution enhancement method using multiple interpolations

2014 ◽  
Author(s):  
Won Hee Kim ◽  
Jei Pil Wang ◽  
Jong Nam Kim
Keyword(s):  
Resolution Enhancement ◽  
Image Resolution ◽  
Enhancement Method

Intrinsic Image Decomposition-Based Resolution Enhancement for Mineral Mapping

2020 ◽  
Author(s):  
Puhong Duan ◽  
Pedram Ghamisi ◽  
Robert Jackisch ◽  
Xudong Kang ◽  
Richard Gloaguen ◽  
...  
Keyword(s):  
Resolution Enhancement ◽  
Image Decomposition ◽  
Mineral Mapping

scholarly journals DMAS Beamforming with Complementary Subset Transmit for Ultrasound Coherence-Based Power Doppler Detection in Multi-Angle Plane-Wave Imaging

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4856
Author(s):  
Che-Chou Shen ◽  
Yen-Chen Chu
Keyword(s):  
Plane Wave ◽  
Power Doppler ◽  
P Value ◽  
Low Resolution ◽  
Ensemble Averaging ◽  
Stationary Tissue ◽  
Wave Imaging ◽  
Acquisition Delay ◽  
Complementary Subset ◽  
Low Resolution Images

Conventional ultrasonic coherent plane-wave (PW) compounding corresponds to Delay-and-Sum (DAS) beamforming of low-resolution images from distinct PW transmit angles. Nonetheless, the trade-off between the level of clutter artifacts and the number of PW transmit angle may compromise the image quality in ultrafast acquisition. Delay-Multiply-and-Sum (DMAS) beamforming in the dimension of PW transmit angle is capable of suppressing clutter interference and is readily compatible with the conventional method. In DMAS, a tunable p value is used to modulate the signal coherence estimated from the low-resolution images to produce the final high-resolution output and does not require huge memory allocation to record all the received channel data in multi-angle PW imaging. In this study, DMAS beamforming is used to construct a novel coherence-based power Doppler detection together with the complementary subset transmit (CST) technique to further reduce the noise level. For p = 2.0 as an example, simulation results indicate that the DMAS beamforming alone can improve the Doppler SNR by 8.2 dB compared to DAS counterpart. Another 6-dB increase in Doppler SNR can be further obtained when the CST technique is combined with DMAS beamforming with sufficient ensemble averaging. The CST technique can also be performed with DAS beamforming, though the improvement in Doppler SNR and CNR is relatively minor. Experimental results also agree with the simulations. Nonetheless, since the DMAS beamforming involves multiplicative operation, clutter filtering in the ensemble direction has to be performed on the low-resolution images before DMAS to remove the stationary tissue without coupling from the flow signal.

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