scholarly journals The Time-Domain Integration Method of Digital Subtraction Angiography Images

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Shuo Huang ◽  
Le Cheng ◽  
Bin Zhu ◽  
Ping Zhou ◽  
Yu Sun ◽  
...  
Keyword(s):  
Digital Subtraction Angiography ◽  
Time Domain ◽  
Noise Suppression ◽  
Integration Method ◽  
Enhancement Effect ◽  
Digital Subtraction ◽  
Denoising Method ◽  
Signal Image ◽  
The Time Domain ◽  
Domain Integration

The clarity improvement and the noise suppression of digital subtraction angiography (DSA) images are very important. However, the common methods are very complicated. An image time-domain integration method is proposed in this study, which is based on the blood flow periodicity. In this method, the images of the first cardiac cycle after the injection of the contrast agent are integrated to obtain the time-domain integration image. This method can be used independently or as a postprocessing method of the denoising method on the signal image. The experimental results on DSA data from an aortic dissection patient show that the image time-domain integration method is efficient in image denoising and enhancement, which also has a good real-time performance. This method can also be used to improve the denoising and image enhancement effect of some common models.

scholarly journals Filter Realization of the Time-Domain Average Denoising Method for a Mechanical Signal

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wuwei Feng ◽  
Cuizhu Wang ◽  
Xin Chen ◽  
Yuzhou Shi ◽  
Meng Jiang ◽  
...  
Keyword(s):  
Time Domain ◽  
Large Error ◽  
Processing Technique ◽  
Signal Processing Technique ◽  
Denoising Method ◽  
Practical Applications ◽  
Noise Interference ◽  
Mechanical Signal ◽  
The Time Domain ◽  
Periodic Components

Time-domain averaging (TDA) is an effective signal processing technique in fault diagnosis that can extract the periodic components of interest from signals mixed with noise interference while suppressing other irrelevant periodic signals. However, there are two obvious shortcomings to TDA: first, the acquisition of keyphasor signals is often restricted by the application environment and conditions. Even if the signal is obtained by TDA, owing to the existence of periodic truncation errors, satisfactory results cannot be obtained. Second, due to the velocity fluctuation, the actual mechanical signal is easy to produce a large error in TDA stacking. To solve the above challenges, first, based on the disadvantage of using traditional resampling to solve the TDA synchronization problem, this paper proposes a new method of subsection resampling, which improves the analysis effect of the traditional TDA. Second, to further expand the range of the practical applications, according to the amplitude-frequency map of TDA, a method for realizing TDA function by using the FIR multiband filter is proposed. This approach effectively avoids the requirement of traditional methods to collect the keyphasor signals and broadens the application in practical engineering. Finally, the improved TDA method is compared with the filter implementation technology, and their respective application conditions are given.

scholarly journals EVOLUTION OF ELECTROMAGNETIC AND DIRAC PERTURBATIONS AROUND A BLACK HOLE IN HOŘAVA GRAVITY

2011 ◽  
Vol 26 (22) ◽  
pp. 1645-1656 ◽  
Author(s):  
NIJO VARGHESE ◽  
V. C. KURIAKOSE
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Time Domain ◽  
Quasinormal Modes ◽  
Late Time ◽  
Spacetime Geometry ◽  
Field Evolution ◽  
The Time Domain ◽  
Integration Data ◽  
Domain Integration

The evolution of electromagnetic and massless Dirac perturbations in the spacetime geometry of Kehagias–Sfetsos (KS) black hole in the deformed Hořava–Lifshitz (HL) gravity is investigated and the associated quasinormal modes (QNMs) are evaluated from time domain integration data. We find a considerable deviation in the nature of field evolution in HL theory from that in the Schwarzschild spacetime and QNM region extends over a longer time in HL theory before the power-law tail decay begins. The dependence of the field evolution on the HL parameter α is also studied. In the time domain picture we find that the length of QNM region increases with α. But the late-time decay of field follows the same power-law tail behavior as in the case of Schwarzschild black hole.

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