As a nondestructive testing technology, γ-photon imaging shows immense potential in the industrial field. However, the limitations of γ-photon imaging theory and detection technology result in various problems, such as low image resolution and edge blur. The technology is particularly difficult to apply to industrial detection that requires high imaging speed and high resolution. Therefore, this study proposes a reconstruction algorithm for regions of interest (ROI) in γ-photon images. The proposed algorithm is suitable for fast industrial detection and is based on the reconstruction algorithm for sinusoidal graph data, that is, the ordered subset expectation maximization (OSEM) image reconstruction algorithm. It is an improvement of the traditional point-and-line system matrix (SM) model. In the application of the proposed algorithm, the probability weight of a pixel is determined by the solid angle of the crystal bar at both ends of the line of response (LOR) to the pixel it passes through. In this work, the known contour parameters of industrial parts are used to describe the area of nuclide distribution as the ROI. Only the pixels through which the LOR passed in the ROI are counted, and the probability weights of these pixels are calculated to construct the SM. Gaussian filters are added in each iteration to suppress the clutter of scattered noise inside the image. The effectiveness of the algorithm was verified in two model experiments. A closed cavity detection experiment on industrial hydraulic parts was also conducted to compare the image reconstruction effects before and after the improvement. Results showed that the proposed algorithm can effectively improve image resolution and image edge contours. In the tee pipe model experiment and cavity detection experiment on hydraulic parts, the image reconstruction speed increased by more than 6 and 10 times, respectively. Hence, the proposed algorithm provided a feasible solution for quickly obtaining images with clear edges and high resolution under a large aperture detector ring.INDEX TERMS γ-photon imaging, OSEM, ROI, system matrix, industrial nondestructive testing
The purpose of this study is to advance an objective evaluation system to describe the acoustic characteristics of Chinese vowels in subjects who had undergone a total laryngectomy and compare the results with those obtained in a control group of subjects who spoke normally. Compared to subjective evaluation system, the new evaluation system would be of important guiding significance for the practice of clinical vocal rehabilitation.
Tracheoesophageal (TE) speech has been the current preferred treatment for speech rehabilitation after total laryngectomy, but due to the lack of objective evaluation criteria, it is tough to operate a qualitative analysis on the effects of postoperative speech rehabilitation. The present paper advanced an objective evaluation system involving acoustic characteristics parameters such as fundamental frequency, formants, jitter, shimmer, harmonics to noise ratio(HNR), the maximum phonation time(MPT), sound intensity and so on. The result showed that compared to subjective evaluation system, the application of objective evaluation system evaluated the effects of speech rehabilitation after total laryngectomy more objectively and precisely.
A methodology for mechanical products assembly design defect identification was presented based on assembly constraint verification tree (ACVT). An identification system framework, which consists of verification tree constructors, modifier, monitor and identification analyzer, was proposed. Modified design parameters were stored into modifier, monitor was employed to supervise design parameters variation in modifier and renew design parameters information in verification tree, identification analyzer decided the start or stop of verification according to stack information in monitor. A prototype system based on above identification system framework was developed, assembly design defects identification results for driving leg of parallel manipulators demonstrate that not only can it enhance identification efficiency for assembly design defects effectively, but also can implement dynamic relating identification for assembly design defects of mechanical products.
The whisper conversion technology is to transform undistinguished whispers with lower SNR into clear normal speech, and it has important application prospect in mobile communication. Because the whisper speech is stirred by the yawp source, its formant position shifts and its bandwidth increases, which induces the problem of formant combination occurs in the whisper conversion. By analyzing the power spectrum, in this article, we proposed a modified adaptive algorithm for formant bandwidth. Based on the rule that the pole power does not change, the algorithm has resolved the problem of formant combination by modifying the formant bandwidth of whisper before implementing formant conversion. The experimental results with six Chinese mandarin monophthong phoneme conversions proved the validity of the algorithm.
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