Gerotor pump is a special kind of internal rotary pump, which contains a trochoid profile (commonly called as cycloid). Generation of trochoid is normally realized by external rolling method, namely a circle rotating ...Gerotor pump is a special kind of internal rotary pump, which contains a trochoid profile (commonly called as cycloid). Generation of trochoid is normally realized by external rolling method, namely a circle rotating on a fixed circle without slipping. This paper proposes derivative process of the trochoid profile by means of internal rolling method, which is that internal surface of a circle contacts with a fixed circle and rotates around it without slipping. Moreover the instantaneous flow rate can be obtained by numerically calculating the change ratio of area between the inner and outer rotors in the outlet region of the gerotor pump, which avoids to complicatedly derivative process.展开更多
Objectives To elucidate the clinical relevance of nonlinear HRV with postoperative arrhythmias in patients undergoing off-pump CABG. Methods Twenty-seven elective off-pump CABG patients were recruited in the present ...Objectives To elucidate the clinical relevance of nonlinear HRV with postoperative arrhythmias in patients undergoing off-pump CABG. Methods Twenty-seven elective off-pump CABG patients were recruited in the present study. Atrial fibrillation （AF）, ventricular tachycardia （VT）, linear and nonlinear HRV were analysed using 24-hour electrocardiogram before and after surgery. Results All time domain （SDNN, pNN50 and rMSSD）, frequency domain （LF and HF） of linear measures of HRV variables and nonlinear measures of HRV variable, the short-term fractal-like correlation α1 decreased significantly after surgery. The postoperative nonlinear HRV variable α1 tended to be lower in patients with postoperative AF （ P = 0. 056 ）. Significant depressed α1 was found in patients with postoperative VT （P = 0. 022 ）. Elder patient＇s age and longer inotropic treatment time negatively correlated with postoperative α1. Conclusions Off-pump CABG procedures resulted in significant depressed of linear and nonlinear HRV variables. The depressed nonlinear HRV variables α1 related to age, inotropic supports and postoperative AF and VT.展开更多
抽水蓄能具有突出的能量密度和功率密度优势。借助其快速响应和灵活调节能力,能够有效平抑新能源出力随机波动,提高系统频率稳定性。针对抽水蓄能如何融入电力系统频率稳定控制问题,提出一种基于转速保护的变速抽蓄自适应综合惯量控制策...抽水蓄能具有突出的能量密度和功率密度优势。借助其快速响应和灵活调节能力,能够有效平抑新能源出力随机波动,提高系统频率稳定性。针对抽水蓄能如何融入电力系统频率稳定控制问题,提出一种基于转速保护的变速抽蓄自适应综合惯量控制策略,并采用优化思想对控制参数进行求解。在考虑短期频率变化率(rate of change of frequency,RoCoF)预测及变速抽蓄自适应综合惯量控制响应系统频率变化的基础上,对传统电力系统低频切泵策略进行改进,提出定速抽蓄自适应低频切泵控制策略。通过不同场景下的仿真验证,结果表明,将变速抽蓄自适应综合惯量调频控制策略与改进低频切泵策略相结合能够更好地适应高比例新能源电力系统,提升系统的频率调节性能。展开更多
文摘Gerotor pump is a special kind of internal rotary pump, which contains a trochoid profile (commonly called as cycloid). Generation of trochoid is normally realized by external rolling method, namely a circle rotating on a fixed circle without slipping. This paper proposes derivative process of the trochoid profile by means of internal rolling method, which is that internal surface of a circle contacts with a fixed circle and rotates around it without slipping. Moreover the instantaneous flow rate can be obtained by numerically calculating the change ratio of area between the inner and outer rotors in the outlet region of the gerotor pump, which avoids to complicatedly derivative process.
文摘Objectives To elucidate the clinical relevance of nonlinear HRV with postoperative arrhythmias in patients undergoing off-pump CABG. Methods Twenty-seven elective off-pump CABG patients were recruited in the present study. Atrial fibrillation （AF）, ventricular tachycardia （VT）, linear and nonlinear HRV were analysed using 24-hour electrocardiogram before and after surgery. Results All time domain （SDNN, pNN50 and rMSSD）, frequency domain （LF and HF） of linear measures of HRV variables and nonlinear measures of HRV variable, the short-term fractal-like correlation α1 decreased significantly after surgery. The postoperative nonlinear HRV variable α1 tended to be lower in patients with postoperative AF （ P = 0. 056 ）. Significant depressed α1 was found in patients with postoperative VT （P = 0. 022 ）. Elder patient＇s age and longer inotropic treatment time negatively correlated with postoperative α1. Conclusions Off-pump CABG procedures resulted in significant depressed of linear and nonlinear HRV variables. The depressed nonlinear HRV variables α1 related to age, inotropic supports and postoperative AF and VT.
文摘抽水蓄能具有突出的能量密度和功率密度优势。借助其快速响应和灵活调节能力,能够有效平抑新能源出力随机波动,提高系统频率稳定性。针对抽水蓄能如何融入电力系统频率稳定控制问题,提出一种基于转速保护的变速抽蓄自适应综合惯量控制策略,并采用优化思想对控制参数进行求解。在考虑短期频率变化率(rate of change of frequency,RoCoF)预测及变速抽蓄自适应综合惯量控制响应系统频率变化的基础上,对传统电力系统低频切泵策略进行改进,提出定速抽蓄自适应低频切泵控制策略。通过不同场景下的仿真验证,结果表明,将变速抽蓄自适应综合惯量调频控制策略与改进低频切泵策略相结合能够更好地适应高比例新能源电力系统,提升系统的频率调节性能。
