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| 1 | 衍射时差图像处理与缺陷识别技术综述显示文摘焊缝是压力容器的质量薄弱环节,焊缝缺陷直接影响压力容器的安全运行。衍射时差(time of flight diffraction,TOFD)检测是目前焊缝质量评价的主要手段。随着TOFD成像检测技术的不断发展,TOFD成像结果自动判读的不足,正成为制约TOFD检测规模化应用的障碍。图像处理和缺陷识别是TOFD成像检测的技术关键。将TOFD图像处理技术归纳为噪声去除、直通波处理、曲线拟合和图像分割,将TOFD缺陷识别技术归纳为特征提取和模式分类,详细介绍了中外的相关研究成果,并对TOFD图像分割、特征提取和缺陷分类识别的研究提出了建议。 | 宋强 李海华 高国刚 贡军民 林森明 | 2021 | 科学技术与工程2021，21，36： | 4 |
| 2 | Comparison of Four Forward Models for Breast Imaging in Ultrasound Computed Tomography显示文摘Ultrasound computed tomography(USCT)is considered to have great potential for breast cancer screening.Compared with ray-based methods,Waveform inversion(WI)methods obtain high spatial resolution images because they consider higher-order diffraction effects.For the WI method,considering more properties of the medium in a forward model can estimate more accurate images.However,longer reconstruction time is required.Therefore,to reduce the reconstruction time,three hypotheses are set in this work to develop the medium under different conditions.We compare the reconstructed images using the four forward models to analyze the effects of the various considered medium properties,which include the sound speed,density of the medium,acoustic absorption and dispersion.To reduce the difficulty of hardware manufacturing,a square border ultrasonic transducer array is adopted in the USCT data acquisition system.Penalized leastsquares optimization problems are constructed to obtain numerical solutions of the sound speed and bulk modulus distributions.The reconstruction of the bulk modulus makes the reconstructed sound speed images more accurate.Computer simulations are conducted to compare reconstructed images using the four forward models under different noise conditions.A numerical breast phantom is used to evaluate the performance.The results suggest that for breast imaging,the forward model(which only considers the heterogeneous sound speed)is a compromise option between image accuracy and computational time. | LI Ruijing CHEN Houjin PENG Yahui LI Jupeng | 2019 | Chinese Journal of Electronics2019，28，4： | 2 |
| 3 | Numerical Study of Square Border Ultrasonic Transducer Element Arrays for Breast Imaging in Ultrasound Computed Tomography with Waveform Inversion Method显示文摘Ultrasound computed tomography (USCT) is a promising approach for early breast cancer screening. Existing studies that estimate breast images using Waveform inversion (WI) methods utilize a Circular ultrasonic transducer element array (CUTA) to collect the measurement data. However, very accurate transducer element positioning and directivity are required for signal calibration in the hardware system of these studies, thereby causing difficulties in hardware manufacturing. The purpose of this study is to estimate high-resolution USCT images using a WI method with a Square border ultrasonic transducer element array (SUTA), which reduces the difficulty of hardware manufacturing and creates accurate correspondence between the continuous and discrete forms of the transducer element positions. Therefore, in this study, an SUTA is adopted to collect the measurement data of breast imaging using the WI method. A penalized least-squares optimization problem is constructed to obtain the numerical solution of a sound speed distribution. Computer simulations are conducted to compare images reconstructed from the measurement data that are collected using an SUTA and a CUTA. The performance is evaluated using a numerical breast phantom. Results suggest that the biases of the images reconstructed are less than 1% with the evenly distributed SUTA and 1% with the CUTA, under a noise condition. | LI Ruijing CHEN Houjin PENG Yahui LI Jupeng | 2019 | Chinese Journal of Electronics2019，28，5： | 2 |
| 4 | Ultrasound Computed Tomography of Knee Joint显示文摘Ultrasound computed tomography(UCT)is considered to have great potential for the early diagnosis of knee joint injuries.Combining prior knowledge and sound speeds of tissues,UCT can diagnose a variety of symptoms and the extent of tissue lesion.However,no existing studies can reconstruct the sound speed distributions of knee joints in UCT.Therefore,in this study,sound speed distributions of knee joints are reconstructed to provide an imaging basis for the formulation of a treatment plan.In addition,Full waveform inversion(FWI)methods are utilized to estimate highresolution images.However,for media with large variations in sound speeds,traditional FWI methods may lead to a cycle-skipping phenomenon and incorrect convergence direction.Hence,this study proposes a multi-centerfrequency source based FWI method to overcome the above limitations.A penalized least-squares optimization problem is constructed to obtain a numerical solution of the sound speed distribution.Computer simulations are conducted to prove the effectiveness and robustness of the proposed method.Furthermore,the reasons for selecting the center frequencies of sources are analyzed.Two numerical knee joint phantoms are used to evaluate the performance.The results suggest that the biases of the reconstructed images are less than 1% under a 5% noise condition. | LI Ruijing CHEN Houjin PENG Yahui LI Jupeng LI Yanfeng | 2020 | Chinese Journal of Electronics2020，29，4： | 0 |
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