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
Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a proje...Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy’s law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use;where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.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Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy’s law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use;where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.
