This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feed...This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feedback loop and to solve the problem of phase ambiguity,the tracking performance of the algorithm has been improved greatly. Only a few preambles are needed in the al-gorithm since the preambles are not used to estimate the frequency offset but used to provide the variation information of the phase due to the presence of frequency offset. Simulations verify that the algorithm has low SNR bound for tracking as well as high tracking accuracy and the tracking range is expanded to 30% of one subcarrier spacing.展开更多
Mechanical ventilation is an effective medical means in the treatment of patients with critically ill,COVID-19 and other pulmonary diseases.During the mechanical ventilation and the weaning process,the conduct of pulm...Mechanical ventilation is an effective medical means in the treatment of patients with critically ill,COVID-19 and other pulmonary diseases.During the mechanical ventilation and the weaning process,the conduct of pulmonary rehabilitation is essential for the patients to improve the spontaneous breathing ability and to avoid the weakness of respiratory muscles and other pulmonary functional trauma.However,inappropriate mechanical ventilation strategies for pulmonary rehabilitation often result in weaning difficulties and other ventilator complications.In this article,the mechanical ventilation strategies for pulmonary rehabilitation are studied based on the analysis of patient-ventilator interaction.A pneumatic model of the mechanical ventilation system is established to determine the mathematical relationship among the pressure,the volumetric flow,and the tidal volume.Each ventilation cycle is divided into four phases according to the different respiratory characteristics of patients,namely,the triggering phase,the inhalation phase,the switching phase,and the exhalation phase.The control parameters of the ventilator are adjusted by analyzing the interaction between the patient and the ventilator at different phases.A novel fuzzy control method of the ventilator support pressure is proposed in the pressure support ventilation mode.According to the fuzzy rules in this research,the plateau pressure can be obtained by the trigger sensitivity and the patient’s inspiratory effort.An experiment prototype of the ventilator is established to verify the accuracy of the pneumatic model and the validity of the mechanical ventilation strategies proposed in this article.In addition,through the discussion of the patient-ventilator asynchrony,the strategies for mechanical ventilation can be adjusted accordingly.The results of this research are meaningful for the clinical operation of mechanical ventilation.Besides,these results provide a theoretical basis for the future research on the intelligent control of ventilator and the automation of weaning process.展开更多
基金the Natural Science Foundation of Jiangsu Province (BK2006701)the National Natural Science Foundation of China (No.60672079).
文摘This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feedback loop and to solve the problem of phase ambiguity,the tracking performance of the algorithm has been improved greatly. Only a few preambles are needed in the al-gorithm since the preambles are not used to estimate the frequency offset but used to provide the variation information of the phase due to the presence of frequency offset. Simulations verify that the algorithm has low SNR bound for tracking as well as high tracking accuracy and the tracking range is expanded to 30% of one subcarrier spacing.
基金supported by the National Natural Science Foundation of China(Grant No.52005015)the China Postdoctoral Science Foundation(Grant No.2019M660391)+3 种基金the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201920)the Outstanding Young Scientists in Beijing(Grant No.BJJWZYJH01201910006021)the National Key Research and Development Project(Grant No.2019YFC0121700)the Clinical research support project of PLA General Hospital(Grant Nos.2019-XXJSYX-13 and2019XXMBD-013)。
文摘Mechanical ventilation is an effective medical means in the treatment of patients with critically ill,COVID-19 and other pulmonary diseases.During the mechanical ventilation and the weaning process,the conduct of pulmonary rehabilitation is essential for the patients to improve the spontaneous breathing ability and to avoid the weakness of respiratory muscles and other pulmonary functional trauma.However,inappropriate mechanical ventilation strategies for pulmonary rehabilitation often result in weaning difficulties and other ventilator complications.In this article,the mechanical ventilation strategies for pulmonary rehabilitation are studied based on the analysis of patient-ventilator interaction.A pneumatic model of the mechanical ventilation system is established to determine the mathematical relationship among the pressure,the volumetric flow,and the tidal volume.Each ventilation cycle is divided into four phases according to the different respiratory characteristics of patients,namely,the triggering phase,the inhalation phase,the switching phase,and the exhalation phase.The control parameters of the ventilator are adjusted by analyzing the interaction between the patient and the ventilator at different phases.A novel fuzzy control method of the ventilator support pressure is proposed in the pressure support ventilation mode.According to the fuzzy rules in this research,the plateau pressure can be obtained by the trigger sensitivity and the patient’s inspiratory effort.An experiment prototype of the ventilator is established to verify the accuracy of the pneumatic model and the validity of the mechanical ventilation strategies proposed in this article.In addition,through the discussion of the patient-ventilator asynchrony,the strategies for mechanical ventilation can be adjusted accordingly.The results of this research are meaningful for the clinical operation of mechanical ventilation.Besides,these results provide a theoretical basis for the future research on the intelligent control of ventilator and the automation of weaning process.
