The work condition of nuclear power plant (NPP) is very bad, which makes ithas faults easily. In order to diagnose (he faults real time, the fusion diagnosis system is built.The data fusion fault diagnosis system adop...The work condition of nuclear power plant (NPP) is very bad, which makes ithas faults easily. In order to diagnose (he faults real time, the fusion diagnosis system is built.The data fusion fault diagnosis system adopts data fusion method and divides the fault diagnosisinto three levels, which are data fusion level, feature level and decision level. The feature leveluses three parallel neural networks whose structures are the same. The purpose of using neuralnetworks is mainly to get basic probability assignment ( BPA) of D-S evidence theory, and the neuralnetworks in feature level are used for local diagnosis. D-S evidence theory is adopted to integratethe local diagnosis results in decision level. The reactor coolant system is the study object andwe choose 2# steam generator U-tubes break of the reactor coolant system as a diagnostic example.The experiments prove that the fusion diagnosis system can satisfy the fault diagnosis requirementof complicated system, and verify that the fusion fault diagnosis system can realize the faultdiagnosis of NPP on line timely.展开更多
Previous studies emphasize the important role of a "north-ridge versus south-trough" dipole (affecting the latitudes from 20° to 75° N around the Tibetan Plateau) of anomalous geopotential height (...Previous studies emphasize the important role of a "north-ridge versus south-trough" dipole (affecting the latitudes from 20° to 75° N around the Tibetan Plateau) of anomalous geopotential height ( Z ) in the early-2008 abnormal cryogenic freezing-rain-and-snow events in the southern part of China. The present study intends to extract the leading signal facilitating the dipole based on the numerical outputs of a full Z-linear model for diagnosing the global Z . Using this model built on full primitive equations in spherical-isobaric coordinates, we can further split the anomaly of Z-Zfζ-uβ (representing the Z component not explicitly associated with the Coriolis parameter f and its meridional derivative β ) into 15 components. With the model-output Zfζ-uβ (mainly accounting for the dipole under the geostrophic balance) and Z-Zfζ-uβ matrices as the left and right singular vectors respectively, a maximum covariance analysis (MCA) is performed to extract the significant 2-4-day leading signal carried by the MCA Z-Zfζ-uβ mode in the upstream area of the dipole. This leading signal is mainly attributed to 1) the abnormally strong westerlies centered around the exit region of the Atlantic jet-stream and 2) the corresponding anomalous 950-300 hPa anticyclone to the south of the abnormally strong center of westerlies. The energy of the positive wave center around this jet exit region favors the downstream north-ridge while the energy of the negative wave center associated with the anomalous anticyclone favors the downstream south-trough.展开更多
Objective： The aim of our study was to investigate the value of Diffusion-weighted MR imaging （DWl） for evaluating differential diagnosis of pulmonary isolated lesions. Methods： Twenty-seven consecutive patients e...Objective： The aim of our study was to investigate the value of Diffusion-weighted MR imaging （DWl） for evaluating differential diagnosis of pulmonary isolated lesions. Methods： Twenty-seven consecutive patients enrolled in this study, all of whom underwent single direction DWl examinations and received a histologic and clinical diagnosis. Diffusion factor B value was 300, 500, 800 s/mm2, respectively. DWl images of twenty cases could be satisfied to measurement and diagnosis and success rate was percent 74. Among these, lung tuberculoma 5 cases, harmatoma 3 cases, peripheral lung cancer 12 cases. The apparent diffusion coefficient （ADC） values of the lesions were measured. Statistical analyses were performed with the independent samples t test for comparing difference of ADC values between malignant nodules and benign nodules at different 8 value. Results： DWI images of twenty cases could be satisfied and its success rate was percent 74. When B value was 300 s/mm2, ADC values of malignant nodules and benign nodules were 0.002192±0.0006091 mm2/s, 0.002454 ± 0.0007892 mm2/s, respectively, and P = 0.442. When B value was 500 s/mm2, ADC value of malignant nodules and benign nodules were 0.002065 ± 0.0006769 mm2/s, 0.002871± 0.0007746 mm2/s, respectively, and P = 0.033. When B value was 800 s/mm2, ADC value of malignant nodules and benign nodules were 0.001646 ± 0.0004292 mm2/s, 0.002651 ＋ 0.0008041 mm2/s, respectively, and P = 0.009. There were the most different between malignant nodules and benign nodules at B value 800 and statistical significance. Conclusion： Lung DWl imaging is helpful to diagnosis and differential diagnosis between malignant and benign isolated nodules. The ADC value of benign lesions was statistically higher than that of malignant tumors.展开更多
文摘The work condition of nuclear power plant (NPP) is very bad, which makes ithas faults easily. In order to diagnose (he faults real time, the fusion diagnosis system is built.The data fusion fault diagnosis system adopts data fusion method and divides the fault diagnosisinto three levels, which are data fusion level, feature level and decision level. The feature leveluses three parallel neural networks whose structures are the same. The purpose of using neuralnetworks is mainly to get basic probability assignment ( BPA) of D-S evidence theory, and the neuralnetworks in feature level are used for local diagnosis. D-S evidence theory is adopted to integratethe local diagnosis results in decision level. The reactor coolant system is the study object andwe choose 2# steam generator U-tubes break of the reactor coolant system as a diagnostic example.The experiments prove that the fusion diagnosis system can satisfy the fault diagnosis requirementof complicated system, and verify that the fusion fault diagnosis system can realize the faultdiagnosis of NPP on line timely.
基金National Key Basic Research Project of China (2009CB421404)a key project of Chinese National Science Foundation (40930950+2 种基金 40730951)Chinese National Science Foundation (40575021)General Program of CAFUC (J2010-29)
文摘Previous studies emphasize the important role of a "north-ridge versus south-trough" dipole (affecting the latitudes from 20° to 75° N around the Tibetan Plateau) of anomalous geopotential height ( Z ) in the early-2008 abnormal cryogenic freezing-rain-and-snow events in the southern part of China. The present study intends to extract the leading signal facilitating the dipole based on the numerical outputs of a full Z-linear model for diagnosing the global Z . Using this model built on full primitive equations in spherical-isobaric coordinates, we can further split the anomaly of Z-Zfζ-uβ (representing the Z component not explicitly associated with the Coriolis parameter f and its meridional derivative β ) into 15 components. With the model-output Zfζ-uβ (mainly accounting for the dipole under the geostrophic balance) and Z-Zfζ-uβ matrices as the left and right singular vectors respectively, a maximum covariance analysis (MCA) is performed to extract the significant 2-4-day leading signal carried by the MCA Z-Zfζ-uβ mode in the upstream area of the dipole. This leading signal is mainly attributed to 1) the abnormally strong westerlies centered around the exit region of the Atlantic jet-stream and 2) the corresponding anomalous 950-300 hPa anticyclone to the south of the abnormally strong center of westerlies. The energy of the positive wave center around this jet exit region favors the downstream north-ridge while the energy of the negative wave center associated with the anomalous anticyclone favors the downstream south-trough.
文摘Objective： The aim of our study was to investigate the value of Diffusion-weighted MR imaging （DWl） for evaluating differential diagnosis of pulmonary isolated lesions. Methods： Twenty-seven consecutive patients enrolled in this study, all of whom underwent single direction DWl examinations and received a histologic and clinical diagnosis. Diffusion factor B value was 300, 500, 800 s/mm2, respectively. DWl images of twenty cases could be satisfied to measurement and diagnosis and success rate was percent 74. Among these, lung tuberculoma 5 cases, harmatoma 3 cases, peripheral lung cancer 12 cases. The apparent diffusion coefficient （ADC） values of the lesions were measured. Statistical analyses were performed with the independent samples t test for comparing difference of ADC values between malignant nodules and benign nodules at different 8 value. Results： DWI images of twenty cases could be satisfied and its success rate was percent 74. When B value was 300 s/mm2, ADC values of malignant nodules and benign nodules were 0.002192±0.0006091 mm2/s, 0.002454 ± 0.0007892 mm2/s, respectively, and P = 0.442. When B value was 500 s/mm2, ADC value of malignant nodules and benign nodules were 0.002065 ± 0.0006769 mm2/s, 0.002871± 0.0007746 mm2/s, respectively, and P = 0.033. When B value was 800 s/mm2, ADC value of malignant nodules and benign nodules were 0.001646 ± 0.0004292 mm2/s, 0.002651 ＋ 0.0008041 mm2/s, respectively, and P = 0.009. There were the most different between malignant nodules and benign nodules at B value 800 and statistical significance. Conclusion： Lung DWl imaging is helpful to diagnosis and differential diagnosis between malignant and benign isolated nodules. The ADC value of benign lesions was statistically higher than that of malignant tumors.
