The air supply and pressure regulating system is a basic part of the physical and chemical regenerative life protection and non-regenerative life protection of manned spacecraft.One of the key systems for the smooth operation of the system.In order to ensure the on-orbit safety and reliability of the high-pressure gas source in the gas supply and pressure regulation system,a two-stage pressure reducing valve is often used to reduce and stabilize the pressure,so as to provide downstream products with low-pressure gas with stable flow and velocity;therefore the pressure reducing valve is an important part to ensure the safety of the gas source.In this paper,based on the structure and principle of a certain type of double-stage pressure reducing valve,the simulation model of the double-stage pressure reducing valve is established by using the pneumatic and pneumatic component design library of AMESim,and the model is compared and verified by experimental data.The results show that the simulation model predicts the working process of the pressure reducing valve well,and the simulation scheme and model are accurate and effective.On this basis,the AMESim simulation model is used to analyze the key process design parameters such as spring stiffness,spool mass and damping hole cross-sectional area of the pressure reducing valve,and the influence laws on the output pressure of the pressure reducing valve and the structural dynamic characteristics are obtained.The findings presented in this paper offer valuable research insights and theoretical support for enhancing the performance of the two-stage pressure reducing valve,as well as providing useful references for future design improvements and on-orbit upgrades.

Objective To evaluate the efficacy of one stage anterior debridement combined with posterior pedicle screw fixation in the treatment of cervical intervertebral space infection.Methods From June 2010 to June 2016,28 cases were fixed by anterior debridement combined with the posterior vertebral pedicle screws for the cervical intervertebral space infection,19 males and 9 females.The average age was 45-74 years (58±14.5 years old).21 cases (75％) were spontaneous infection,of which 6 cases were diabetes mellitus,15 cases were over 60 years old.The remaining 7 cases (25％) were intervertebral space infection after radiofrequency ablation of the cervical spine.All patients were excluded from tuberculosis and Brucella infection.All patients underwent hematological examination,with emphasis on WBC,ESP and CRP.All patients received JOA score before operation,applied antibiotic according to blood culture and drug sensitive test.All patients underwent one stage anterior debridement combined with posterior pedicle screw fixation,and the operative time and bleeding volume were recorded.After the operation,intravenous antibiotic therapy was continued,and the application of antibiotics was guided according to the results of ESP and CRP,and the time for the application of antibiotics was recorded.Follow up was performed at 3 months,6 months and 1 years after operation respectively.The JOA score and postoperative cervical lordosis Cobb angle were recorded.Results All operations were successfully completed in this group.The operation time was 130-225 min,with an average of 145.5±12.7 min.The intraoperative blood loss was 40-100 ml,with an average of 67±35.2 ml.The incision was healed in one stage.The time of application of antibiotics in 28 patients was 21-87 days,with an average of 30.8±8.7 days.The longest application time of antibiotics was 87 days,and no relapse was found during follow-up.The postoperative JOA score increased from 11.3± 1.2 to three months 14.9 ± 1.96 postoperatively and 6 months 15.1 ± 1.55 and 1 years 16.5±0.48 after operation.The JOA score was significantly higher than that before operation.No significant loss and change of the Cobb angle in the cervical spine surgery were found.All cases had good bone graft fusion at 1 years.Conclusion One stage anterior debridement combined with posterior pedicle screw fixation is a safe and effective method for the treatment of cervical vertebra instability and nerve function injury caused by cervical intervertebral space infection.It provides a new way for the treatment of cervical intervertebral space infection.