The Maximum Entropy Method in Ultrasonic Non-Destructive Testing—Increasing the Resolution, Image Noise Reduction and Echo Acquisition Rate

Abstract

Abstract:The use of linear methods, for example, the Combined Synthetic Aperture Focusing Technique (C-SAFT), does not allow one to obtain images with high resolution and low noise, especially structural noise in all cases. Non-linear methods should improve the quality of the reconstructed image. Several examples of the application of the maximum entropy (ME) method for ultrasonic echo processing in order to reconstruct the image of reflectors with Rayleigh super-resolution and a high signal-to-noise ratio are considered in the article. The use of the complex phase-shifted Barker code signal as a probe pulse and the compression of measured echoes by the ME method made it possible to increase the signal-to-noise ratio by more than 20 dB for the image of a flat-bottom hole with a diameter of 1 mm in a model experiment. A modification of the ME method for restoring the reflector image by the time-of-flight diffraction (TOFD) method is considered, taking into account the change of the echo signal shape, depending on the depth of the reflector. Using the ME method, 2.5D-images of models of dangling cracks in a pipeline with a diameter of 800 mm were obtained, which make it possible to determine their dimensions. In the object with structural noise, using the ME method, it was possible to increase the signal-to-noise ratio of the reflector image by more than 12 dB. To accelerate the acquisition of echoes in the dual scan mode, it is proposed to use code division multiple access (CDMA) technology based on simultaneous emission by all elements of the array of pseudo-orthogonal signals. The model experiment showed the effectiveness of applying the ME method.

Intelligent Noise Reduction Algorithm to Evaluate the Correlation between Human Fat Deposits and Uterine Fibroids under Ultrasound Imaging

“…In ultrasound imaging, the interference position of the ultrasound echo signal was random. Therefore, the speckle noise on the ultrasound image was also random [ 19 ]. In the resolution unit of the ultrasound image, a Rayleigh distributed random variable could be applied to describe the intensity of the ultrasound echo scattering signal.…”

Development of magnetic image super-resolution model for nondestructive testing

“…The input low-resolution magnetic image X is duplicated and fed into the First DNN block H1 and Block 1 F1. The results of F1(X) and H1() are then added to produce an output of the first stage Y1, as described by equation (4).…”

“…However, the accurate determination of sub-pixel image shift values remains a challenge in this method. Another avenue of research has explored the application of the maximum entropy method to enhance the quality of ultrasonic images, resulting in reduced structural noise of cracks and improved echo signal length [4]. A deep learning DL model was developed to reconstruct ultrasonic Lamb wave images with high spatial resolution [5].…”

“…However, determining the image shift values in the sub-pixel level remains a challenging problem with this method. Another study [4] utilized the maximum entropy method to enhance the quality of ultrasonic images, resulting in a reduction of structural noise of cracks and the duration of echo signal length. In [6], a super-resolution algorithm was combined with NSST to fuse MFL data of double detection boards and improve the quality of crack images.…”

Neuroprotective Effect of Monosialotetrahexosylganglioside (GM1) on Patients with Parkinson’s Disease Anesthetized by Ketamine under Denoising Algorithm-Based Ultrasound Image Diagnosis

“…ere are many forms of diagnosis commonly used in medical diagnosis, and B ultrasound is a very common method. Ultrasonic imaging technology, X-ray diagnostic technology, and isotope technology have been identified as the three latest medical imaging technologies [13]. It is widely used in the pathological diagnosis of cardiovascular disease, the liver, spleen, gallbladder, pleura, and the other parts of the human body and also plays an important role in the diagnosis of fetal morphology in obstetrics department.…”