As the differences of sensor＇s precision and some random factors are difficult to control,the actual measurement signals are far from the target signals that affect the reliability and precision of rotating machinery...As the differences of sensor＇s precision and some random factors are difficult to control,the actual measurement signals are far from the target signals that affect the reliability and precision of rotating machinery fault diagnosis.The traditional signal processing methods,such as classical inference and weighted averaging algorithm usually lack dynamic adaptability that is easy for trends to cause the faults to be misjudged or left out.To enhance the measuring veracity and precision of vibration signal in rotary machine multi-sensor vibration signal fault diagnosis,a novel data level fusion approach is presented on the basis of correlation function analysis to fast determine the weighted value of multi-sensor vibration signals.The approach doesn＇t require knowing the prior information about sensors,and the weighted value of sensors can be confirmed depending on the correlation measure of real-time data tested in the data level fusion process.It gives greater weighted value to the greater correlation measure of sensor signals,and vice versa.The approach can effectively suppress large errors and even can still fuse data in the case of sensor failures because it takes full advantage of sensor＇s own-information to determine the weighted value.Moreover,it has good performance of anti-jamming due to the correlation measures between noise and effective signals are usually small.Through the simulation of typical signal collected from multi-sensors,the comparative analysis of dynamic adaptability and fault tolerance between the proposed approach and traditional weighted averaging approach is taken.Finally,the rotor dynamics and integrated fault simulator is taken as an example to verify the feasibility and advantages of the proposed approach,it is shown that the multi-sensor data level fusion based on correlation function weighted approach is better than the traditional weighted average approach with respect to fusion precision and dynamic adaptability.Meantime,the approach is adaptable and easy to use,can be appl展开更多
受激发条件和氢核响应机理的限制,核磁测井原始回波信号极其微弱。高信噪比的回波信号在反演算法中能够更加真实的反映地层信息,于是设计一个高增益、低噪声的接收机非常关键。基于核磁原始回波信号的幅频特性分析,利用低噪声前置放大...受激发条件和氢核响应机理的限制,核磁测井原始回波信号极其微弱。高信噪比的回波信号在反演算法中能够更加真实的反映地层信息,于是设计一个高增益、低噪声的接收机非常关键。基于核磁原始回波信号的幅频特性分析,利用低噪声前置放大器、滤波单元、A/D转换器、改进的数字相敏检波处理单元,设计实现了一个高信噪比多频数字接收机。该接收机已经成功应用于中海油自主研发的核磁共振测井仪(elis magnetic resonance tool,EMRT)上,在渤海油田得到的测井曲线CHI值表明该接收机工作稳定,提取信号信噪比高。展开更多
目的：探讨3.0 T MR扩散加权成像不同b值的信号强度及ADC值下降率对乳腺良恶性病变的诊断价值。方法对东南大学附属中大医院自2010年12月至2012年12月经手术病理证实的152例162个乳腺病灶（恶性85灶，良性77灶）行3.0 T MR DWI扫描，b值...目的：探讨3.0 T MR扩散加权成像不同b值的信号强度及ADC值下降率对乳腺良恶性病变的诊断价值。方法对东南大学附属中大医院自2010年12月至2012年12月经手术病理证实的152例162个乳腺病灶（恶性85灶，良性77灶）行3.0 T MR DWI扫描，b值取0、400、800、1000 s/mm2，分别测量不同b值下乳腺病灶DWI信号强度及ADC值，计算DWI信号强度下降率（SIDR）， SIDR＝（低b值DWI病灶信号强度-高b值DWI病灶信号强度）/低b值DWI病灶信号强度及ADC值下降率（ ADCDR），ADCDR＝（低b值病灶ADC值-高b值病灶ADC值）/低b值病灶ADC值）。对所获得的资料采用两独立样本t检验进行统计学分析并采用ROC曲线评价SIDR值及ADCDR值的诊断效能。结果（1）0～400、400～800和800～1000 s/mm23组b值间良、恶性病灶SIDR差异均有统计学意义（均P＜0.01）。（2）3组b值间的SIDR对良恶性病变诊断的敏感性分别为61.2％、68.2％和67.1％，特异性分别为74.0％、85.7％和67.5％；诊断符合率分别为67.3％、76.5％和67.3％；阳性预测值分别为72.2％、84.1％和69.5％；阴性预测值分别为63.3％、71.0％和65.0％。（3）400～800、800～1000 s/mm2两组 b值间良、恶性病灶ADCDR差异均有统计学意义（均P＜0.01）。（4）两组b值间的ADCDR对良恶性病变诊断的敏感性分别为80.0％、65.9％，特异性分别为72.7％、65.0％；诊断符合率分别为76.5％、65.4％；阳性预测值分别为76.4％、67.5％；阴性预测值分别为76.7％、63.3％。结论不同b值的信号强度下降率及ADC值下降率对乳腺良恶病灶都具有鉴别诊断价值，且诊断效能以400～800 s/mm2间为最佳。展开更多
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2007AA04Z433)Hunan Provincial Natural Science Foundation of China (Grant No. 09JJ8005)Scientific Research Foundation of Graduate School of Beijing University of Chemical and Technology,China (Grant No. 10Me002)
文摘As the differences of sensor＇s precision and some random factors are difficult to control,the actual measurement signals are far from the target signals that affect the reliability and precision of rotating machinery fault diagnosis.The traditional signal processing methods,such as classical inference and weighted averaging algorithm usually lack dynamic adaptability that is easy for trends to cause the faults to be misjudged or left out.To enhance the measuring veracity and precision of vibration signal in rotary machine multi-sensor vibration signal fault diagnosis,a novel data level fusion approach is presented on the basis of correlation function analysis to fast determine the weighted value of multi-sensor vibration signals.The approach doesn＇t require knowing the prior information about sensors,and the weighted value of sensors can be confirmed depending on the correlation measure of real-time data tested in the data level fusion process.It gives greater weighted value to the greater correlation measure of sensor signals,and vice versa.The approach can effectively suppress large errors and even can still fuse data in the case of sensor failures because it takes full advantage of sensor＇s own-information to determine the weighted value.Moreover,it has good performance of anti-jamming due to the correlation measures between noise and effective signals are usually small.Through the simulation of typical signal collected from multi-sensors,the comparative analysis of dynamic adaptability and fault tolerance between the proposed approach and traditional weighted averaging approach is taken.Finally,the rotor dynamics and integrated fault simulator is taken as an example to verify the feasibility and advantages of the proposed approach,it is shown that the multi-sensor data level fusion based on correlation function weighted approach is better than the traditional weighted average approach with respect to fusion precision and dynamic adaptability.Meantime,the approach is adaptable and easy to use,can be appl
文摘受激发条件和氢核响应机理的限制,核磁测井原始回波信号极其微弱。高信噪比的回波信号在反演算法中能够更加真实的反映地层信息,于是设计一个高增益、低噪声的接收机非常关键。基于核磁原始回波信号的幅频特性分析,利用低噪声前置放大器、滤波单元、A/D转换器、改进的数字相敏检波处理单元,设计实现了一个高信噪比多频数字接收机。该接收机已经成功应用于中海油自主研发的核磁共振测井仪(elis magnetic resonance tool,EMRT)上,在渤海油田得到的测井曲线CHI值表明该接收机工作稳定,提取信号信噪比高。
