Background The middle ear pneumatic system(MEPS)supports pressure balance,essential for sound conduction.Its volume and surface area are key indicators of pneumatization and ventilation,yet their specific contribution...Background The middle ear pneumatic system(MEPS)supports pressure balance,essential for sound conduction.Its volume and surface area are key indicators of pneumatization and ventilation,yet their specific contributions to pressure regulation need further exploration.Objective To evaluate the accuracy and sensitivity of parameters characterizing the MEPS,including volume(V),surface area(S),and surface-area-to-volume ratio(S/V),in normal ears.Materials and Methods We collected CT images of the temporal bone from 63 normal ears for this study.The volume(V),surface area(S),and surface-area-to-volume ratio(S/V)of the MEPS were measured and calculated using three-dimensional reconstruction technology.Statistical methods were used to process the data and determine the 95%reference range for the S,V,and S/V of the MEPS in the normal ear.At the same time,we analyzed the impact of differences in gender and the left and right sides on the measurements.Results The 95%reference values for the S,V,and S/V of the MEPS in normal ears were 1057.10~18239.16 mm²,609.16~9854.11 mm^(3),and 1.39~2.52 mm^(-1) respectively.There were no significant differences in the measurements between genders and between the left and right sides.Conclusions and Significance This study has established the 95%reference values for the S,V,and S/V of the MEPS in normal ears,which were 1057.10-18239.16 mm²,609.16-9854.11 mm^(3),and 1.39-2.52 mm^(-1) respectively.We found that while there is a wide variation in the V values among normal ears,there is less variability in the S/V values.This structural characteristic suggests that changes in the S/V value may have a more significant impact on the balance of middle ear pressure,and it provides important reference data for the construction and functional reconstruction of three-dimensional models of the MEPS.These findings may aid in diagnosing middle ear disorders,such as otitis media with effusion,and guide interventions to restore pressure balance.展开更多
The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have ...The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.展开更多
The condensation in pneumatic system is a complex physical phenomenon dependant upon status variation and phase transitions,which are related to the parameters of the compressed air,atmospheric conditions and the dime...The condensation in pneumatic system is a complex physical phenomenon dependant upon status variation and phase transitions,which are related to the parameters of the compressed air,atmospheric conditions and the dimensions of the pneumatic components.Up to now,general research method for this problem is to calculate the status variation and movement quantity by numerical simulation and experiment directly.The comprehensive parameters composed of several different effect factors are rarely used to study the condensation.The composed components and the working conditions of each cylinder are different,a large number of experiments and complex calculations are necessary to determine the condensation.Additionally,the transferability of the determined results is poor.In this paper,the charging and discharging systems of serials cylinder with different structure parameters are studied.The condensation of the systems is observed and the effects of the structure parameters on condensation are analyzed.The changing trends of relative humidity,natural frequency and average speed against the structural parameters of the components during discharge of the pneumatic systems are analyzed.Three comprehensive parameters used to analyze and determine condensation composed by structure parameters of components are proposed,namely,the ratio of the effective area of the discharge tube and the container volume,the square root of the effective area of the discharge tube divided by the product of the container volume and the length of the discharge tube,and the discharge dimensionless tube-volume.The experimental results show that these comprehensive parameters can be used to quantitatively determine whether internal,external or zero condensation occurs in a pneumatic system,and can be also used to quantitatively analyze the experimental data of condensation in pneumatic systems directly.At the same time,the effect factors are too much and the effect relationships are very complex,which causes that the conclusions can＇t be put forward by using single effect factor in experimental data processing individually.The three obtained comprehensive parameters can be used to resolve the above problem.The proposed parameters can also resolve the problem of poor transferability in determining the state of condensation in pneumatic systems,and provide a novel method for the further study of condensation theory.展开更多
Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation ...Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation as well as measurement methods should be proposed, and their applicability should be validated. In this paper, firstly, power evaluation and measurement methods of pneumatic system were introduced for the first time. Secondly, based on the proposed methods, power distributions in pneumatic system was analyzed. Thirdly, through the analysis on pneumatic efficiencies of typical compressors and pneumatic components, the applicability of the proposed methods were validated. It can be concluded that, first of all, the proposed methods to evaluation and measurement the power of pneumatic system were efficient. Furthermore, the pneumatic power efficiencies of pneumatic system in the air production and cleaning procedure are respectively about 35%–75% and 85%–90%. Moreover, the pneumatic power efficiencies of pneumatic system in the transmission and consumption procedures are about 70%–85% and 10%–35%. And the total pneumatic power efficiency of pneumatic system is about 2%–20%, which varies largely with the system configuration. This paper provides a method to analyze and measure the power of pneumatic system, lay a foundation for the optimization and energy-saving design of pneumatic system.展开更多
Fault detection and diagnosis for pneumatic system of automatic productionline are studied. An expert system using fuzzy-neural network and pneumatic circuit fault diagnosisinstrument are deigned. The mathematical mod...Fault detection and diagnosis for pneumatic system of automatic productionline are studied. An expert system using fuzzy-neural network and pneumatic circuit fault diagnosisinstrument are deigned. The mathematical model of various pneumatic faults and experimental deviceare built. In the end, some experiments are done, which shows that the expert system usingfuzzy-neural network can diagnose fast and truly fault of pneumatic circuit.展开更多
In this work, a new device for tidal energy conversion is presented. The main purpose of this research is to investigate the energy conversion of tidal energy into electrical one by building a small scale prototype us...In this work, a new device for tidal energy conversion is presented. The main purpose of this research is to investigate the energy conversion of tidal energy into electrical one by building a small scale prototype using a pneumatic system representing the energy conversion device. The tidal energy conversion device consists of a concrete in cylindrical shape, a moving base that moves inside the concrete cylindrical body and two single acting pistons connected to a power turbine. The system specifications that mainly affect the amount of energy are the spring stiffness and hose diameter. It was found that there is a possibility to convert the tidal energy into electrical energy using the designed prototype. The maximum amount of electricity generated using the proposed prototype was about 5 Volts.展开更多
Pneumatic technology,as one of the core basic industrial automation technologies,has been greatly developed because of its clean,high efficiency,low cost,and easy maintenance advantages.In particular,gas flow control ...Pneumatic technology,as one of the core basic industrial automation technologies,has been greatly developed because of its clean,high efficiency,low cost,and easy maintenance advantages.In particular,gas flow control technology has been widely used in new energy vehicles,the petrochemical industry,and other fields.The typical pneumatic technical principles and electronic pressure/flow controllers are shown in Figure 1.展开更多
Because of significantly changed load and complex and variable driving road conditions of commercial vehicles,pneumatic suspension with lower natural frequencies is widely used in commercial vehicle suspension system....Because of significantly changed load and complex and variable driving road conditions of commercial vehicles,pneumatic suspension with lower natural frequencies is widely used in commercial vehicle suspension system.How ever,traditional pneumatic suspension system is hardly to respond the greatly changed load of commercial vehicles To address this issue,a new Gas-Interconnected Quasi-Zero Stiffness Pneumatic Suspension(GIQZSPS)is presented in this paper to improve the vibration isolation performance of commercial vehicle suspension systems under frequent load changes.This new structure adds negative stiffness air chambers on traditional pneumatic suspension to reduce the natural frequency of the suspension.It can adapt to different loads and road conditions by adjusting the solenoid valves between the negative stiffness air chambers.Firstly,a nonlinear mechanical model including the dimensionless stiffness characteristic and interconnected pipeline model is derived for GIQZSPS system.By the nonlinear mechanical model of GIQZSPS system,the force transmissibility rate is chosen as the evaluation index to analyze characteristics.Furthermore,a testing bench simulating 1/4 GIQZSPS system is designed,and the testing analysis of the model validation and isolating performance is carried out.The results show that compared to traditional pneumatic suspension,the GIQZSPS designed in the article has a lower natural frequency.And the system can achieve better vibration isolation performance under different load states by switching the solenoid valves between air chambers.展开更多
Four-dimensional(4D)printing represents a groundbreaking advancement in manufacturing,yet a persistent challenge is the limited number of stable configurations achievable through spontaneous shape reconstruction.Herei...Four-dimensional(4D)printing represents a groundbreaking advancement in manufacturing,yet a persistent challenge is the limited number of stable configurations achievable through spontaneous shape reconstruction.Herein,we present a novel 4D printing mechanism that utilizes self-adjustable gas pressure to facilitate a wide range of spontaneous and stable multi-shape transformations.The gas is precisely released at designated spatial locations through strategic temperature-controlled degradation of a solid material,which is printed and distributed as needed at the voxel level within a specially designed multi-material structure,consisting of a low degradation temperature material(LDTM),a high degradation temperature soft material(HDTSM),and a high degradation temperature hard material(HDTHM).Each shape configuration is determined and locked in by the maximum temperature experienced during its thermal history.Notably,this shape retains its form robustly,independently of subsequent temperature changes,until a higher temperature threshold is reached,at which point a new shape configuration is triggered.These shapes exhibit a remarkable temperature memory effect,permanently recording the peak temperature reached in their thermal history.Our study comprehensively investigates the underlying principles and key parameters that influence deformation.We present a series of examples demonstrating complex multi-shape transformations modulated by temperature,supported by finite element simulations.This advance in 4D printing has the potential to significantly enhance its functional capabilities,performance,and applicability,opening up new horizons in additive manufacturing and design.展开更多
The complex dense-phase pneumatic conveying of pulverized coal process was studied using an electrical capacitance tomography(ECT) signal that represented the motion characteristics of gas-solid two-phase flow. The fl...The complex dense-phase pneumatic conveying of pulverized coal process was studied using an electrical capacitance tomography(ECT) signal that represented the motion characteristics of gas-solid two-phase flow. The fluctuation characteristics of conveying process signals are inseparable from the flow pattern. The denoised ECT signal and noise signal were obtained by db2 wavelet analysis. It was found that all noise signals were white Gaussian noise. Based on the assumption of the equal probability distribution of pulverized coal concentration, this paper proved that the time series distribution of pulverized coal concentration in the pipeline should obey the normal distribution. Furthermore, through the analysis of the distribution characteristics of the power spectral density function of denoised ECT signals of four flow patterns, they were α-dimensional fractal Brownian motion(fBm) signals, and the parameter α was estimated by the detrended fluctuation analysis. Based on the fBm characteristics of denoised ECT signals and white Gaussian noise, this paper proposed a method for calculating the pulverized coal concentration in the dense-phase pneumatic conveying. In addition to the method of concentration estimation with the significance of engineering guidance, this research can help people to further understand essential characteristics of ECT signals in the dense-phase pneumatic conveying.展开更多
Vibrations or dither's are features of the PWM servo control system in their steady outputs. On the grounds of analyses and experiments of a PWM pneumatic servo control system, the paper puts forward four varietie...Vibrations or dither's are features of the PWM servo control system in their steady outputs. On the grounds of analyses and experiments of a PWM pneumatic servo control system, the paper puts forward four varieties of PWM modulation methods, and concludes on the relationship between dithers and the different methods, and then discusses the influence of friction to the dithers. Results from experiments regarding the dynamic and static responses on the given system support the theories presented.展开更多
A high current, AC waveform controller with C-type body frame of spot welder(75 k VA), was examined for the electrode actuating system whose pneumatically driven system has been redesigned and refitted for the servo b...A high current, AC waveform controller with C-type body frame of spot welder(75 k VA), was examined for the electrode actuating system whose pneumatically driven system has been redesigned and refitted for the servo based system without any vertical spring assistance in the 50 mm movable distance. Moreover, the pressing mechanism was carefully handled during the entire pressing tasks as to ensure that no catastrophic reaction happens for the electrodes' caps, electrodes' holders as well as the other part of mechanical assembly. With the mechanically originated-pneumatic and also the converted-servo systems, the stainless steels are welded for both systems to characterize the improvements. While the welding processes were carried out, the electrical signals have been captured to compute the signals' representation of entire sequences. Later, the welded samples were underwent the tensile shear test, metallurgical observation and hardness test. The analytical results show distinct changes in the force profiles which has led to profound changes in mechanical properties of welded specimens.展开更多
With the price decreasing of the pneumatic proportional valve and the high performance micro controller, the simple structure and high tracking performance pneumatic servo system demonstrates more application potentia...With the price decreasing of the pneumatic proportional valve and the high performance micro controller, the simple structure and high tracking performance pneumatic servo system demonstrates more application potential in many fields. However, most existing control methods with high tracking performance need to know the model information and to use pressure sensor. This limits the application of the pneumatic servo system. An adaptive backstepping slide mode control method is proposed for pneumatic position servo system. The proposed method designs adaptive slide mode controller using backstepping design technique. The controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. A theorem is testified to show that the state of closed-loop system is uniformly bounded, and the closed-loop system is stable. The advantages of the proposed method include that system dynamic model parameters are not required for the controller design, uncertain parameters bounds are not need, and the bulk and expensive pressure sensor is not needed as well. Experimental performance, as compared with some existing methods. results show that the designed controller can achieve better tracking展开更多
The pneumatic pressure control systems have been used in some fields. However, the researches on pneumatic pressure control mainly focus on constant pressure regulation. Poor dynamic characteristics and strong nonline...The pneumatic pressure control systems have been used in some fields. However, the researches on pneumatic pressure control mainly focus on constant pressure regulation. Poor dynamic characteristics and strong nonlinearity of such systems limit its application in the field of pressure tracking control. In order to meet the demand of generating dynamic pressure signal in the application of the hardware-in-the-loop simulation of aerospace engineering, a positive and negative pneumatic pressure servo system is provided to implement dynamic adjustment of sealed chamber pressure. A mathematical model is established with simulation and experiment being implemented afterwards to discuss the characteristics of the system, which shows serious asymmetry in the process of charging and discharging. Based on the analysis of the system dynamics, a fuzzy proportional integral derivative （PID） controller with asymmetric fuzzy compensator is proposed. Different from conventional adjusting mecha- nisms employing the error and change in error of the controlled variable as input parameters, the current cham- ber pressure and charging or discharging state are chosen as inputs of the compensator, which improves adaptability. To verify the effectiveness and performance of the pro- posed controller, the comparison experiments tracking sinusoidal and square wave commands are conducted. Experimental results show that the proposed controller can obtain better dynamic performance and relatively consis- tent control performance across the scope of work （2-140 kPa）. The research proposes a fuzzy control method to overcome asymmetry and enhance adaptability for the positive and negative pneumatic pressure servo system.展开更多
When saving energy in a pneumatic system,the problem of energy losses is usually solved by reducing the air supply pressure.The power-matching method is applied to optimize the air-supply pressure of the pneumatic sys...When saving energy in a pneumatic system,the problem of energy losses is usually solved by reducing the air supply pressure.The power-matching method is applied to optimize the air-supply pressure of the pneumatic system,and the energy-saving effect is verified by experiments.First,the experimental platform of a pneumatic rotary actuator servo-control system is built,and the mechanism of the valve-controlled cylinder system is analyzed.Then,the output power characteristics and load characteristics of the system are derived,and their characteristic curves are drawn.The employed air compressor is considered as a constant-pressure source of a quantitative pump,and the power characteristic of the system is matched.The power source characteristic curve should envelope the output characteristic curve and load characteristic curve.The minimum gas supply pressure obtained by power matching represents the optimal gas supply pressure.The comparative experiments under two different gas supply pressure conditions show that the system under the optimal gas supply pressure can greatly reduce energy losses.展开更多
This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonl...This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and the active control force is constructed by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.展开更多
The pneumatic rotary position system, in which an electro-pneumatic proportional flow valve controled a rotary cylinder, was studied, and its mathematical model was built. The model indicated that the controlled pneum...The pneumatic rotary position system, in which an electro-pneumatic proportional flow valve controled a rotary cylinder, was studied, and its mathematical model was built. The model indicated that the controlled pneumatic system had disadvantages such as inherent non-linearity and variations of system parameters with working points. In order to improve the dynamic performance of the system, feed forward compensation self-tuning pole-placement strategy was adopted to place the poles of the system in a desired position in real time, and a recursive least square method with fixed forgetting factors was also used in the parameter estimation. Experimental results show that the steady state error of the pneumatic rotary position system is within 3% and the identified system parameters can be converged in 5 s. Under different loads, the controlled system has an excellent tracking performance and robustness of anti-disturbance.展开更多
In this paper, a novel control law is presented, which uses neural-network techniques to approximate the affine class nonlinear system having unknown or uncertain dynamics and noise disturbances. It adopts an adaptive...In this paper, a novel control law is presented, which uses neural-network techniques to approximate the affine class nonlinear system having unknown or uncertain dynamics and noise disturbances. It adopts an adaptive control law to adjust the network parameters online and adds another control component according to H-infinity control theory to attenuate the disturbance. This control law is applied to the position tracking control of pneumatic servo systems. Simulation and experimental results show that the tracking precision and convergence speed is obviously superior to the results by using the basic BP-network controller and self-tuning adaptive controller.展开更多
The reliability and safety of the pneumatic ducts are essential for flight safety.A beam element model of the duct system is developed and the factors that impact the stress performance of the duct system are investig...The reliability and safety of the pneumatic ducts are essential for flight safety.A beam element model of the duct system is developed and the factors that impact the stress performance of the duct system are investigated,such as stress check standards,flight acceleration,internal temperature and internal pressure.The results show that the stress synthetic method as the stress check standard can obtain the more safety design results.The maximum stress of straight pipe is affected significantly by the acceleration in a plane perpendicular to straight pipe,while the maximum stress of bend pipe is greatly affected by the acceleration in the direction perpendicular to plane of the bend pipe.Meanwhile,internal pressure has little effect on the maximum stress of bend pipe and straight pipe.Temperature has little effect on the maximum stress of bend pipe while has a big impact on the maximum stress of straight pipe.展开更多
A pneumatic actuator is a fast and economical tool that converts compressed air into mechanical motion.In this paper,an extended state observer(ESO)-based sliding mode controller(SMC)is developed to adjust the air pre...A pneumatic actuator is a fast and economical tool that converts compressed air into mechanical motion.In this paper,an extended state observer(ESO)-based sliding mode controller(SMC)is developed to adjust the air pressure of the actua-tor for accurate position control,Specifically,an impedance control module is established to produce desired air pressure based on the relationship between forces and desired positions.Then,the ESO-based SMC is implemented to adjust the air pressure to the required level despite the presence of system uncertainties and disturbances.As a result,the position of the actuator is controlled to a setpoint through the regulation of pressure.The performance of ESO-based SMC is compared with that of a classic active disturbance rciection controller(ADRC)and a SMC.Simulation results demonstrate that the:ESO-based SMC shows comparable performance to ADRC in terms of precise pressure control.In addition,it requires the least control effort ncessary to excite valves among the three controllers.The stability of ESO based SMC is theoretically justifed through Lyapunov approach.展开更多
基金supported by the[National Natural Science Foundation of China]under Grant[number 12172082][Catch up with and surpass technology projects]under Grant[number 2022LCJSGC24]。
文摘Background The middle ear pneumatic system(MEPS)supports pressure balance,essential for sound conduction.Its volume and surface area are key indicators of pneumatization and ventilation,yet their specific contributions to pressure regulation need further exploration.Objective To evaluate the accuracy and sensitivity of parameters characterizing the MEPS,including volume(V),surface area(S),and surface-area-to-volume ratio(S/V),in normal ears.Materials and Methods We collected CT images of the temporal bone from 63 normal ears for this study.The volume(V),surface area(S),and surface-area-to-volume ratio(S/V)of the MEPS were measured and calculated using three-dimensional reconstruction technology.Statistical methods were used to process the data and determine the 95%reference range for the S,V,and S/V of the MEPS in the normal ear.At the same time,we analyzed the impact of differences in gender and the left and right sides on the measurements.Results The 95%reference values for the S,V,and S/V of the MEPS in normal ears were 1057.10~18239.16 mm²,609.16~9854.11 mm^(3),and 1.39~2.52 mm^(-1) respectively.There were no significant differences in the measurements between genders and between the left and right sides.Conclusions and Significance This study has established the 95%reference values for the S,V,and S/V of the MEPS in normal ears,which were 1057.10-18239.16 mm²,609.16-9854.11 mm^(3),and 1.39-2.52 mm^(-1) respectively.We found that while there is a wide variation in the V values among normal ears,there is less variability in the S/V values.This structural characteristic suggests that changes in the S/V value may have a more significant impact on the balance of middle ear pressure,and it provides important reference data for the construction and functional reconstruction of three-dimensional models of the MEPS.These findings may aid in diagnosing middle ear disorders,such as otitis media with effusion,and guide interventions to restore pressure balance.
基金This project is supported by National Natural Science Foundation of China(No.50575209).
文摘The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.
基金supported by National Natural Science Foundation of China (Grant No.50575209)
文摘The condensation in pneumatic system is a complex physical phenomenon dependant upon status variation and phase transitions,which are related to the parameters of the compressed air,atmospheric conditions and the dimensions of the pneumatic components.Up to now,general research method for this problem is to calculate the status variation and movement quantity by numerical simulation and experiment directly.The comprehensive parameters composed of several different effect factors are rarely used to study the condensation.The composed components and the working conditions of each cylinder are different,a large number of experiments and complex calculations are necessary to determine the condensation.Additionally,the transferability of the determined results is poor.In this paper,the charging and discharging systems of serials cylinder with different structure parameters are studied.The condensation of the systems is observed and the effects of the structure parameters on condensation are analyzed.The changing trends of relative humidity,natural frequency and average speed against the structural parameters of the components during discharge of the pneumatic systems are analyzed.Three comprehensive parameters used to analyze and determine condensation composed by structure parameters of components are proposed,namely,the ratio of the effective area of the discharge tube and the container volume,the square root of the effective area of the discharge tube divided by the product of the container volume and the length of the discharge tube,and the discharge dimensionless tube-volume.The experimental results show that these comprehensive parameters can be used to quantitatively determine whether internal,external or zero condensation occurs in a pneumatic system,and can be also used to quantitatively analyze the experimental data of condensation in pneumatic systems directly.At the same time,the effect factors are too much and the effect relationships are very complex,which causes that the conclusions can＇t be put forward by using single effect factor in experimental data processing individually.The three obtained comprehensive parameters can be used to resolve the above problem.The proposed parameters can also resolve the problem of poor transferability in determining the state of condensation in pneumatic systems,and provide a novel method for the further study of condensation theory.
基金Supported by National Natural Science Foundation of China(Grants Nos.51675020,51375028)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems
文摘Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation as well as measurement methods should be proposed, and their applicability should be validated. In this paper, firstly, power evaluation and measurement methods of pneumatic system were introduced for the first time. Secondly, based on the proposed methods, power distributions in pneumatic system was analyzed. Thirdly, through the analysis on pneumatic efficiencies of typical compressors and pneumatic components, the applicability of the proposed methods were validated. It can be concluded that, first of all, the proposed methods to evaluation and measurement the power of pneumatic system were efficient. Furthermore, the pneumatic power efficiencies of pneumatic system in the air production and cleaning procedure are respectively about 35%–75% and 85%–90%. Moreover, the pneumatic power efficiencies of pneumatic system in the transmission and consumption procedures are about 70%–85% and 10%–35%. And the total pneumatic power efficiency of pneumatic system is about 2%–20%, which varies largely with the system configuration. This paper provides a method to analyze and measure the power of pneumatic system, lay a foundation for the optimization and energy-saving design of pneumatic system.
文摘Fault detection and diagnosis for pneumatic system of automatic productionline are studied. An expert system using fuzzy-neural network and pneumatic circuit fault diagnosisinstrument are deigned. The mathematical model of various pneumatic faults and experimental deviceare built. In the end, some experiments are done, which shows that the expert system usingfuzzy-neural network can diagnose fast and truly fault of pneumatic circuit.
文摘In this work, a new device for tidal energy conversion is presented. The main purpose of this research is to investigate the energy conversion of tidal energy into electrical one by building a small scale prototype using a pneumatic system representing the energy conversion device. The tidal energy conversion device consists of a concrete in cylindrical shape, a moving base that moves inside the concrete cylindrical body and two single acting pistons connected to a power turbine. The system specifications that mainly affect the amount of energy are the spring stiffness and hose diameter. It was found that there is a possibility to convert the tidal energy into electrical energy using the designed prototype. The maximum amount of electricity generated using the proposed prototype was about 5 Volts.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0708903)Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology and Advanced Space Propulsion Laboratory of BICE,LabASP-2023-06。
文摘Pneumatic technology,as one of the core basic industrial automation technologies,has been greatly developed because of its clean,high efficiency,low cost,and easy maintenance advantages.In particular,gas flow control technology has been widely used in new energy vehicles,the petrochemical industry,and other fields.The typical pneumatic technical principles and electronic pressure/flow controllers are shown in Figure 1.
基金Supported by National Natural Science Foundation of China (Grant No.51875256)Open Platform Fund of Human Institute of Technology (Grant No.KFA22009)。
文摘Because of significantly changed load and complex and variable driving road conditions of commercial vehicles,pneumatic suspension with lower natural frequencies is widely used in commercial vehicle suspension system.How ever,traditional pneumatic suspension system is hardly to respond the greatly changed load of commercial vehicles To address this issue,a new Gas-Interconnected Quasi-Zero Stiffness Pneumatic Suspension(GIQZSPS)is presented in this paper to improve the vibration isolation performance of commercial vehicle suspension systems under frequent load changes.This new structure adds negative stiffness air chambers on traditional pneumatic suspension to reduce the natural frequency of the suspension.It can adapt to different loads and road conditions by adjusting the solenoid valves between the negative stiffness air chambers.Firstly,a nonlinear mechanical model including the dimensionless stiffness characteristic and interconnected pipeline model is derived for GIQZSPS system.By the nonlinear mechanical model of GIQZSPS system,the force transmissibility rate is chosen as the evaluation index to analyze characteristics.Furthermore,a testing bench simulating 1/4 GIQZSPS system is designed,and the testing analysis of the model validation and isolating performance is carried out.The results show that compared to traditional pneumatic suspension,the GIQZSPS designed in the article has a lower natural frequency.And the system can achieve better vibration isolation performance under different load states by switching the solenoid valves between air chambers.
基金support from the Shenzhen Science and Technology Innovation Commission(Grant No.JCYJ20200109115439775 and JCYJ20230807140459034)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515012645)National Natural Science Foundation of China(Grant No.11872369).
文摘Four-dimensional(4D)printing represents a groundbreaking advancement in manufacturing,yet a persistent challenge is the limited number of stable configurations achievable through spontaneous shape reconstruction.Herein,we present a novel 4D printing mechanism that utilizes self-adjustable gas pressure to facilitate a wide range of spontaneous and stable multi-shape transformations.The gas is precisely released at designated spatial locations through strategic temperature-controlled degradation of a solid material,which is printed and distributed as needed at the voxel level within a specially designed multi-material structure,consisting of a low degradation temperature material(LDTM),a high degradation temperature soft material(HDTSM),and a high degradation temperature hard material(HDTHM).Each shape configuration is determined and locked in by the maximum temperature experienced during its thermal history.Notably,this shape retains its form robustly,independently of subsequent temperature changes,until a higher temperature threshold is reached,at which point a new shape configuration is triggered.These shapes exhibit a remarkable temperature memory effect,permanently recording the peak temperature reached in their thermal history.Our study comprehensively investigates the underlying principles and key parameters that influence deformation.We present a series of examples demonstrating complex multi-shape transformations modulated by temperature,supported by finite element simulations.This advance in 4D printing has the potential to significantly enhance its functional capabilities,performance,and applicability,opening up new horizons in additive manufacturing and design.
基金funding from Shanghai Sailing Program (22YF1417600)Guangxi Science and Technology Major Program (AA23062019)
文摘The complex dense-phase pneumatic conveying of pulverized coal process was studied using an electrical capacitance tomography(ECT) signal that represented the motion characteristics of gas-solid two-phase flow. The fluctuation characteristics of conveying process signals are inseparable from the flow pattern. The denoised ECT signal and noise signal were obtained by db2 wavelet analysis. It was found that all noise signals were white Gaussian noise. Based on the assumption of the equal probability distribution of pulverized coal concentration, this paper proved that the time series distribution of pulverized coal concentration in the pipeline should obey the normal distribution. Furthermore, through the analysis of the distribution characteristics of the power spectral density function of denoised ECT signals of four flow patterns, they were α-dimensional fractal Brownian motion(fBm) signals, and the parameter α was estimated by the detrended fluctuation analysis. Based on the fBm characteristics of denoised ECT signals and white Gaussian noise, this paper proposed a method for calculating the pulverized coal concentration in the dense-phase pneumatic conveying. In addition to the method of concentration estimation with the significance of engineering guidance, this research can help people to further understand essential characteristics of ECT signals in the dense-phase pneumatic conveying.
文摘Vibrations or dither's are features of the PWM servo control system in their steady outputs. On the grounds of analyses and experiments of a PWM pneumatic servo control system, the paper puts forward four varieties of PWM modulation methods, and concludes on the relationship between dithers and the different methods, and then discusses the influence of friction to the dithers. Results from experiments regarding the dynamic and static responses on the given system support the theories presented.
文摘A high current, AC waveform controller with C-type body frame of spot welder(75 k VA), was examined for the electrode actuating system whose pneumatically driven system has been redesigned and refitted for the servo based system without any vertical spring assistance in the 50 mm movable distance. Moreover, the pressing mechanism was carefully handled during the entire pressing tasks as to ensure that no catastrophic reaction happens for the electrodes' caps, electrodes' holders as well as the other part of mechanical assembly. With the mechanically originated-pneumatic and also the converted-servo systems, the stainless steels are welded for both systems to characterize the improvements. While the welding processes were carried out, the electrical signals have been captured to compute the signals' representation of entire sequences. Later, the welded samples were underwent the tensile shear test, metallurgical observation and hardness test. The analytical results show distinct changes in the force profiles which has led to profound changes in mechanical properties of welded specimens.
基金Supported by National Key Scientific and Technological Project(Grant No.2010ZX04001-051-031)Key Program of National Natural Science Foundation of China((Grant No.61533014)the Innovative Research Team of Shaanxi Province,China(Grant No.2013KCT-04)
文摘With the price decreasing of the pneumatic proportional valve and the high performance micro controller, the simple structure and high tracking performance pneumatic servo system demonstrates more application potential in many fields. However, most existing control methods with high tracking performance need to know the model information and to use pressure sensor. This limits the application of the pneumatic servo system. An adaptive backstepping slide mode control method is proposed for pneumatic position servo system. The proposed method designs adaptive slide mode controller using backstepping design technique. The controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. A theorem is testified to show that the state of closed-loop system is uniformly bounded, and the closed-loop system is stable. The advantages of the proposed method include that system dynamic model parameters are not required for the controller design, uncertain parameters bounds are not need, and the bulk and expensive pressure sensor is not needed as well. Experimental performance, as compared with some existing methods. results show that the designed controller can achieve better tracking
基金Supported by National Natural Science Foundation of China(Grant No.51575199)
文摘The pneumatic pressure control systems have been used in some fields. However, the researches on pneumatic pressure control mainly focus on constant pressure regulation. Poor dynamic characteristics and strong nonlinearity of such systems limit its application in the field of pressure tracking control. In order to meet the demand of generating dynamic pressure signal in the application of the hardware-in-the-loop simulation of aerospace engineering, a positive and negative pneumatic pressure servo system is provided to implement dynamic adjustment of sealed chamber pressure. A mathematical model is established with simulation and experiment being implemented afterwards to discuss the characteristics of the system, which shows serious asymmetry in the process of charging and discharging. Based on the analysis of the system dynamics, a fuzzy proportional integral derivative （PID） controller with asymmetric fuzzy compensator is proposed. Different from conventional adjusting mecha- nisms employing the error and change in error of the controlled variable as input parameters, the current cham- ber pressure and charging or discharging state are chosen as inputs of the compensator, which improves adaptability. To verify the effectiveness and performance of the pro- posed controller, the comparison experiments tracking sinusoidal and square wave commands are conducted. Experimental results show that the proposed controller can obtain better dynamic performance and relatively consis- tent control performance across the scope of work （2-140 kPa）. The research proposes a fuzzy control method to overcome asymmetry and enhance adaptability for the positive and negative pneumatic pressure servo system.
基金Supported by Henan Province Science and Technology Key Project of China(Grant Nos.202102210081,202102210082)Fundamental Research Funds for Henan Province Colleges and Universities of China(Grant No.NSFRF140120)Doctor Foundation of Henan Polytechnic University(Grant No.B2012-101).
文摘When saving energy in a pneumatic system,the problem of energy losses is usually solved by reducing the air supply pressure.The power-matching method is applied to optimize the air-supply pressure of the pneumatic system,and the energy-saving effect is verified by experiments.First,the experimental platform of a pneumatic rotary actuator servo-control system is built,and the mechanism of the valve-controlled cylinder system is analyzed.Then,the output power characteristics and load characteristics of the system are derived,and their characteristic curves are drawn.The employed air compressor is considered as a constant-pressure source of a quantitative pump,and the power characteristic of the system is matched.The power source characteristic curve should envelope the output characteristic curve and load characteristic curve.The minimum gas supply pressure obtained by power matching represents the optimal gas supply pressure.The comparative experiments under two different gas supply pressure conditions show that the system under the optimal gas supply pressure can greatly reduce energy losses.
文摘This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and the active control force is constructed by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.
基金Project(50375034) supported by the National Natural Science Foundation of China
文摘The pneumatic rotary position system, in which an electro-pneumatic proportional flow valve controled a rotary cylinder, was studied, and its mathematical model was built. The model indicated that the controlled pneumatic system had disadvantages such as inherent non-linearity and variations of system parameters with working points. In order to improve the dynamic performance of the system, feed forward compensation self-tuning pole-placement strategy was adopted to place the poles of the system in a desired position in real time, and a recursive least square method with fixed forgetting factors was also used in the parameter estimation. Experimental results show that the steady state error of the pneumatic rotary position system is within 3% and the identified system parameters can be converged in 5 s. Under different loads, the controlled system has an excellent tracking performance and robustness of anti-disturbance.
基金Guangdong-Hong Kong Technology Cooperation Funding Scheme (No.2005A10207005, IID 2004-0005)the Research Grants Council of Hong Kong (No.9040407)
文摘In this paper, a novel control law is presented, which uses neural-network techniques to approximate the affine class nonlinear system having unknown or uncertain dynamics and noise disturbances. It adopts an adaptive control law to adjust the network parameters online and adds another control component according to H-infinity control theory to attenuate the disturbance. This control law is applied to the position tracking control of pneumatic servo systems. Simulation and experimental results show that the tracking precision and convergence speed is obviously superior to the results by using the basic BP-network controller and self-tuning adaptive controller.
文摘The reliability and safety of the pneumatic ducts are essential for flight safety.A beam element model of the duct system is developed and the factors that impact the stress performance of the duct system are investigated,such as stress check standards,flight acceleration,internal temperature and internal pressure.The results show that the stress synthetic method as the stress check standard can obtain the more safety design results.The maximum stress of straight pipe is affected significantly by the acceleration in a plane perpendicular to straight pipe,while the maximum stress of bend pipe is greatly affected by the acceleration in the direction perpendicular to plane of the bend pipe.Meanwhile,internal pressure has little effect on the maximum stress of bend pipe and straight pipe.Temperature has little effect on the maximum stress of bend pipe while has a big impact on the maximum stress of straight pipe.
文摘A pneumatic actuator is a fast and economical tool that converts compressed air into mechanical motion.In this paper,an extended state observer(ESO)-based sliding mode controller(SMC)is developed to adjust the air pressure of the actua-tor for accurate position control,Specifically,an impedance control module is established to produce desired air pressure based on the relationship between forces and desired positions.Then,the ESO-based SMC is implemented to adjust the air pressure to the required level despite the presence of system uncertainties and disturbances.As a result,the position of the actuator is controlled to a setpoint through the regulation of pressure.The performance of ESO-based SMC is compared with that of a classic active disturbance rciection controller(ADRC)and a SMC.Simulation results demonstrate that the:ESO-based SMC shows comparable performance to ADRC in terms of precise pressure control.In addition,it requires the least control effort ncessary to excite valves among the three controllers.The stability of ESO based SMC is theoretically justifed through Lyapunov approach.
