The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining ...The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.展开更多
目的:分析血纤维蛋白原(FIB)、肿瘤坏死因子(TNF)-α、D-二聚体(D-D)对急性脑梗死(ACI)患者溶栓后出血性转化(HT)的风险预测价值。方法:收集进行阿替普酶静脉溶栓治疗的急性脑梗死患者166例,根据是否发生HT,分为HT组36例,非HT组130例。...目的:分析血纤维蛋白原(FIB)、肿瘤坏死因子(TNF)-α、D-二聚体(D-D)对急性脑梗死(ACI)患者溶栓后出血性转化(HT)的风险预测价值。方法:收集进行阿替普酶静脉溶栓治疗的急性脑梗死患者166例,根据是否发生HT,分为HT组36例,非HT组130例。对2组的基本资料进行单因素分析,将单因素中差异有统计学意义的指标纳入决策树分析,获得风险因素和决策树模型。使用受试者工作特征(ROC)曲线判定决策树模型的预测价值。结果:2组患者高血压、糖尿病、房颤、脑梗死史、抗血小板药物史、大面积脑梗死史、年龄、溶栓前美国卫生研究院卒中量表(NIHSS)评分及溶栓后24 h的收缩压、白细胞计数、FIB、D-D、TNF-α比较,差异有统计学意义(P均<0.05);决策树分析共获得5层二分类树,包括20个分类节点,10条决策路径:溶栓后24 h D-D>2.58 mg/L、TNF-α>161.74 ng/L、溶栓前NIHSS评分>15分、溶栓后24 h FIB<2.25 mg/L、大面积脑梗死史是ACI患者溶栓后发生HT的独立危险因素(P均<0.05)。该模型的ROC曲线下面积为0.909,95%CI:0.874~0.945,灵敏度86.11%,特异性92.31%。结论:溶栓后24 h D-D、TNF-α、溶栓前NIHSS评分、溶栓后24 h FIB、大面积脑梗死史对ACI静脉溶栓后发生HT具有较高的预测价值。展开更多
基金National Natural Science Foundation of China(No.51675399)。
文摘The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.
文摘目的:分析血纤维蛋白原(FIB)、肿瘤坏死因子(TNF)-α、D-二聚体(D-D)对急性脑梗死(ACI)患者溶栓后出血性转化(HT)的风险预测价值。方法:收集进行阿替普酶静脉溶栓治疗的急性脑梗死患者166例,根据是否发生HT,分为HT组36例,非HT组130例。对2组的基本资料进行单因素分析,将单因素中差异有统计学意义的指标纳入决策树分析,获得风险因素和决策树模型。使用受试者工作特征(ROC)曲线判定决策树模型的预测价值。结果:2组患者高血压、糖尿病、房颤、脑梗死史、抗血小板药物史、大面积脑梗死史、年龄、溶栓前美国卫生研究院卒中量表(NIHSS)评分及溶栓后24 h的收缩压、白细胞计数、FIB、D-D、TNF-α比较,差异有统计学意义(P均<0.05);决策树分析共获得5层二分类树,包括20个分类节点,10条决策路径:溶栓后24 h D-D>2.58 mg/L、TNF-α>161.74 ng/L、溶栓前NIHSS评分>15分、溶栓后24 h FIB<2.25 mg/L、大面积脑梗死史是ACI患者溶栓后发生HT的独立危险因素(P均<0.05)。该模型的ROC曲线下面积为0.909,95%CI:0.874~0.945,灵敏度86.11%,特异性92.31%。结论:溶栓后24 h D-D、TNF-α、溶栓前NIHSS评分、溶栓后24 h FIB、大面积脑梗死史对ACI静脉溶栓后发生HT具有较高的预测价值。
