In this article, a method to control power-assisted carts with motor torque limiter that achieves the desired load-reduction ratio even if torque saturation occurs, is proposed to reduce the size and power consumption...In this article, a method to control power-assisted carts with motor torque limiter that achieves the desired load-reduction ratio even if torque saturation occurs, is proposed to reduce the size and power consumption of power-assist systems. This method uses the ratio of the assist-force impulse to the operator-force impulse as an indicator for evaluating proposed method. Proposed method predicts the needs of the operator and delivers the desired load-reduction ratio by predicting operation. The results show that the target load-reduction ratio can be obtained with proposed control method and indicate that the target load-reduction ratio can be obtained with 80% force. By applying our proposed method, short available time of power-assisted carts will be improved.展开更多
Lean premixed combustion,which allows for reducing the production of thermal NOx,is prone to combustion instabilities.There is an extensive research to develop a reduced physical model,which allows-without time-consum...Lean premixed combustion,which allows for reducing the production of thermal NOx,is prone to combustion instabilities.There is an extensive research to develop a reduced physical model,which allows-without time-consuming measurements-to calculate the resonance characteristics of a combustion system consisting of Helmholtz resonator type components (burner plenum,combustion chamber).For the formulation of this model numerical investigations by means of compressible Large Eddy Simulation (LES) were carried out.In these investigations the flow in the combustion chamber is isotherm,non-reacting and excited with a sinusoidal mass flow rate.Firstly a combustion chamber as a single resonator subsequently a coupled system of a burner plenum and a combustion chamber were investigated.In this paper the results of additional investigations of the single resonator are presented.The flow in the combustion chamber was investigated without excitation at the inlet.It was detected,that the mass flow rate at the outlet cross section is pulsating once the flow in the chamber is turbulent.The fast Fourier transform of the signal showed that the dominant mode is at the resonance frequency of the combustion chamber.This result sheds light on a very important source of self-excited combustion instabilities.Furthermore the LES can provide not only the damping ratio for the analytical model but the eigenfrequency of the resonator also.展开更多
文摘In this article, a method to control power-assisted carts with motor torque limiter that achieves the desired load-reduction ratio even if torque saturation occurs, is proposed to reduce the size and power consumption of power-assist systems. This method uses the ratio of the assist-force impulse to the operator-force impulse as an indicator for evaluating proposed method. Proposed method predicts the needs of the operator and delivers the desired load-reduction ratio by predicting operation. The results show that the target load-reduction ratio can be obtained with proposed control method and indicate that the target load-reduction ratio can be obtained with 80% force. By applying our proposed method, short available time of power-assisted carts will be improved.
文摘Lean premixed combustion,which allows for reducing the production of thermal NOx,is prone to combustion instabilities.There is an extensive research to develop a reduced physical model,which allows-without time-consuming measurements-to calculate the resonance characteristics of a combustion system consisting of Helmholtz resonator type components (burner plenum,combustion chamber).For the formulation of this model numerical investigations by means of compressible Large Eddy Simulation (LES) were carried out.In these investigations the flow in the combustion chamber is isotherm,non-reacting and excited with a sinusoidal mass flow rate.Firstly a combustion chamber as a single resonator subsequently a coupled system of a burner plenum and a combustion chamber were investigated.In this paper the results of additional investigations of the single resonator are presented.The flow in the combustion chamber was investigated without excitation at the inlet.It was detected,that the mass flow rate at the outlet cross section is pulsating once the flow in the chamber is turbulent.The fast Fourier transform of the signal showed that the dominant mode is at the resonance frequency of the combustion chamber.This result sheds light on a very important source of self-excited combustion instabilities.Furthermore the LES can provide not only the damping ratio for the analytical model but the eigenfrequency of the resonator also.
