Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and ...Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and healthy lifestyle index (HLI)with BP control among hypertension patients is seldom reported,which needs to provide more evidence by prospective intervention studies.We examined the association of antihypertensive medication use and HLI with BP control among employees with hypertension in China based on a workplace-based multicomponent intervention program.Methods Between January 2013 and December 2014,a cluster randomized clinical trial of a workplace-based multicomponent intervention program was conducted in 60 workplaces across 20 urban areas in China.Workplaces were randomly divided into intervention (n=40) and control (n=20) groups.Basic information on employees at each workplace was collected by trained professionals,including sociodemographic characteristics,medical history,family history,lifestyle behaviors,medication status and physical measurements.After baseline,the intervention group received a 2-year intervention to achieve BP control,which included:(1) a workplace wellness program for all employees;(2) a guidelines-oriented hypertension management protocol.HLI including nonsmoking,nondrinking,adequate physical activity,weight within reference range and balanced diet,were coded on a 5-point scale (range:0-5,with higher score indicating a healthier lifestyle).Antihypertensive medication use was defined as taking drug within the last 2 weeks.Changes in HLI,antihypertensive medication use and BP control from baseline to 24 months were measured after the intervention.Results Overall,4655 employees were included (age:46.3±7.6 years,men:3547 (82.3%)).After 24 months of the intervention,there was a significant improvement in lifestyle[smoking (OR=0.65,95%CI:0.43-0.99;P=0.045),drinking (OR=0.52,95%CI:0.40-0.68;P<0.001),regular exercise (OR=3.10,95%CI:2.53-3.78;P<0.001),excessive intake of fatty food (OR=0.17,95%CI:0.06-0.52;P=0.002),restrictive use of salt (OR=0.26,95%CI:0.12-0.56;P=0.001)].Compare to employees with a deteriorating lifestyle after the intervention,those with an improved lifestyle had a higher BP control.In the intervention group,compared with employees not using antihypertensive medication,those who consistent used (OR=2.34;95%CI:1.16-4.72;P=0.017) or changed from not using to using antihypertensive medication (OR=2.24;95%CI:1.08-4.62;P=0.030) had higher BP control.Compared with those having lower HLI,participants with a same (OR=1.38;95%CI:0.99-1.93;P=0.056) or high (OR=1.79;95%CI:1.27~2.53;P<0.001) HLI had higher BP control.Those who used antihypertensive medication and had a high HLI had the highest BP control (OR=1.88;95%CI:1.32-2.67,P<0.001).Subgroup analysis also showed the consistent effect as the above.Conclusion These findings suggest that adherence to antihypertensive medication treatment and healthy lifestyle were associated with a significant improvement in BP control among employees with hypertension.展开更多
With the growing demand for offshore energy,deepwater drilling has become a vital technology in petroleum engineering.However,conventional drilling systems often face limitations such as delayed bottomhole pressure re...With the growing demand for offshore energy,deepwater drilling has become a vital technology in petroleum engineering.However,conventional drilling systems often face limitations such as delayed bottomhole pressure response and low control precision,particularly under narrow pressure window and complex formation conditions.To address these challenges,Dual-layer Pipe dual-gradient drilling(DGD)technology has been introduced,utilizing a dual-pipe structure and downhole lift pumps to extend the pressure control range.Despite these advantages,current DGD systems lack fast and precise bottomhole pressure control due to their reliance on indirect flow-based methods.This study proposes a bottomhole pressure control method based on backpressure regulation using a hybrid fuzzy-PID control strategy.A dynamic pressure calculation model is developed for the Dual-layer Pipe DGD system,incorporating coupling among choke valve opening,surface backpressure,and bottomhole pressure.The fuzzy-PID controller adjusts valve operation in real-time based on pressure deviation and its rate of change,improving response speed and control accuracy.Simulink-based simulations demonstrate that the proposed system achieves rapid pressure regulation with an overshoot below 5%and steady-state error under 0.12%.Compared to conventional PID control,the fuzzy-PID system shows superior adaptability to pressure variations.This research enhances the theoretical foundation of backpressure control in deepwater DGD operations and provides a practical approach for improving safety and efficiency in complex drilling environments.展开更多
A turbine design method based on pressure controlled vortex design （PCVD） is presented to design a small-size turbine stage. Contrary to the conventional controlled vortex design （CVD） method, the main objective o...A turbine design method based on pressure controlled vortex design （PCVD） is presented to design a small-size turbine stage. Contrary to the conventional controlled vortex design （CVD） method, the main objective of PCVD is to control the axial velocity and radial pressure in the sta- tor rotor gap. Through controlling axial velocity, the PCVD establishes a direct tie to meridional stream surface. Thus stream surface variation is induced, resulting in a large secondary flow vortex covering the full blade passage in the respective stator and rotor. This secondary flow vortex could be dedicated to control the secondary flow mitigation and migration. Through radial pressure, the PCVD is also associated with the macroscopic driving force of fluid motion. So the better benefit of CVD can be achieved. The core concept behind PCVD is to mainly control the spanwise pressure gradient by altering profile loading at various spanwise locations. Therefore not only the local pro- file lift is affected, but also the resulting throat widths, stage reaction degree, and massflow rate are altered or redistributed respectively. With the PCVD method, the global stage efficiency is increased successfully while the mass flow rate keeps constant. Additionally there is no endwall shape optimization, stacking optimization, or pitch/chord variations, concentrating solely on varying blade profile deflections and stagger.展开更多
Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation si...Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation situation,divergence and vertical velocity field,and the vertical profile of temperature and humidity are synthesized and analyzed.The basic characteristics of the circulation and physical field of sea fog under low pressure control(L type sea fog)are obtained,and the results are compared with the sea fog under the control of high pressure(H type sea fog):a)L type sea fogs potential height anomaly disturbance is mainly manifested in the low layer,and its average value is-65.66 gpm,gradually weakening upward;b)L type sea fogs inversion structure is weaker than H type sea fogs when it occurs,the fog layer is thicker and the high relative humidity level is high over the fog layer,while the H type sea fogs fog layer has a relatively obvious dry layer;c)L sea fog has three layers of structure at the vertical direction.The first layer 1000-950 hPa is convergence accompanied by weak rise and subsidence,the second layer 950-850 hPa is divergence accompanied by weak subsidence,and the third layer 850 to 500hPa is gradually strengthened.While there are two layer structures of the H type sea fog.1000 hPa is divergence accompanied by weak rising and sinking movement,950-500 hPa is a uniform subsidence movement.d)Probability density statistical analysis further quantified the vertical movement of L and H type sea fog and the distribution of relative humidity in each layer.These conclusions provide an important reference for forecasting the sea fog in the northwest of the Yellow Sea under the condition of low pressure circulation in summer.展开更多
This paper describes a supervisory hierarchical fuzzy controller （SHFC） for regulating pressure in a real-time pilot pressure control system. The input scaling factor tuning of a direct expert controller is made usi...This paper describes a supervisory hierarchical fuzzy controller （SHFC） for regulating pressure in a real-time pilot pressure control system. The input scaling factor tuning of a direct expert controller is made using the error and process input parameters in a closed loop system in order to obtain better controller performance for set-point change and load disturbances. This on-line tuning method reduces operator involvement and enhances the controller performance to a wide operating range. The hierarchical control scheme consists of an intelligent upper level supervisory fuzzy controller and a lower level direct fuzzy controller. The upper level controller provides a mechanism to the main goal of the system and the lower level controller delivers the solutions to a particular situation. The control algorithm for the proposed scheme has been developed and tested using an ARM7 microcontroller-based embedded target board for a nonlinear pressure process having dead time. To demonstrate the effectiveness, the results of the proposed hierarchical controller, fuzzy controller and conventional proportional-integral （PI） controller are analyzed. The results prove that the SHFC performance is better in terms of stability and robustness than the conventional control methods.展开更多
In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of t...In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of the pressure controller valve cover in different medium environments is unclear,interference between the valve cover and inner pipe may occur and negatively affect the IPP-Coring success rate.To address this issue,we conducted a series of indoor experiments employing a high-speed camera to gain greater insights into the valve cover rotation behavior in different medium environments,e.g.,air,water,and simulated drilling fluids.The results indicated that the variation in the valve cover rotation angle in the air and fluid environments can be described by a one-phase exponential decay function with a constant time parameter and by biphasic dose response function,respectively.The rotation behavior in the fluid environments exhibited distinct elastic and gravitational acceleration zones.In the fluid environments,the density clearly impacted the valve cover closing time and rotation behavior,whereas the effect of viscosity was very slight.This can be attributed to the negligible influence of the fluid viscosity on the drag coefficient found in this study;meanwhile,the density can increase the buoyancy and the time period during which the valve cover experienced a high drag coefficient.Considering these results,control schemes for the valve cover rotation behavior during IPP-Coring were proposed for different layers and geological conditions in which the different drilling fluids should be used,e.g.,the use of a high-density valve cover in high-pore pressure layers.展开更多
Objective Current clinical evidence on the effects of home blood pressure telemonitoring(HBPT)on improving blood pressure control comes entirely from developed countries.Thus,we performed this randomized controlled tr...Objective Current clinical evidence on the effects of home blood pressure telemonitoring(HBPT)on improving blood pressure control comes entirely from developed countries.Thus,we performed this randomized controlled trial to evaluate whether HBPT plus support(patient education and clinician remote hypertension management)improves blood pressure control more than usual care(UC)in the Chinese population.Methods This single-center,randomized controlled study was conducted in Beijing,China.Patients aged 30-75 years were eligible for enrolment if they had blood pressure[systolic(SBP)≥140 mmHg and/or diastolic(DBP)≥90 mmHg;or SBP≥130 mmHg and/or DBP≥80 mmHg with diabetes].We recruited 190 patients randomized to either the HBPT or the UC groups for 12 weeks.The primary endpoints were blood pressure reduction and the proportion of patients achieving the target blood pressure.Results Totally,172 patients completed the study,the HBPT plus support group(n=84),and the UC group(n=88).Patients in the plus support group showed a greater reduction in mean ambulatory blood pressure than those in the UC group.The plus support group had a significantly higher proportion of patients who achieved the target blood pressure and maintained a dipper blood pressure pattern at the12th week of follow-up.Additionally,the patients in the plus support group showed lower blood pressure variability and higher drug adherence than those in the UC group.Conclusion HBPT plus additional support results in greater blood pressure reduction,better blood pressure control,a higher proportion of dipper blood pressure patterns,lower blood pressure variability,and higher drug adherence than UC.The development of telemedicine may be the cornerstone of hypertension management in primary care.展开更多
Water-assisted injection molding（WAIM）,a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving,short cooling circle time and high quality of products.Ex...Water-assisted injection molding（WAIM）,a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving,short cooling circle time and high quality of products.Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM.However,the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system.In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM,the proportional pressure control of the WAIM system is investigated both numerically and experimentally.A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment,the load characteristics and the nonlinearities of water hydraulic system are both considered,then the main factors affecting the injecting pressure and load flow rate are extensively studied.Meanwhile,an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance.In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene（ABS） parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation.The good coincidence between experiment and simulation shows that the AMEsim model is accurate,and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system.The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.展开更多
The performance of the designed digital electro-pneumatic cabin pressure control system for the cabin pressure schedule of transport aircraft is investigated.For the purpose of this study,an experimental setup consist...The performance of the designed digital electro-pneumatic cabin pressure control system for the cabin pressure schedule of transport aircraft is investigated.For the purpose of this study,an experimental setup consisting of a simulated hermetic cabin and altitude simulation chamber is configured for cabin pressure control system operation.A series of experimental tests are executed to evaluate the performance of the cabin pressure control system.The parameters of the PID controller are optimized.In the optimization process,the variation regularity of the rate of cabin pressure change under various conditions is considered.An approach to prioritize the control of the rate of change of cabin pressure based on the flight status model is proposed and verified experimentally.The experimental results indicate that the proposed approach can be adopted for the designed digital electro-pneumatic cabin pressure control system to obtain a better cabin pressure schedule and rate of cabin pressure change.展开更多
Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer ...Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer unit is usually equipped. However, the pump motor energy transfer has the characteristics of poor starting and low response, which cause long time of pressure adjustment and large pressure jitter when the transformer is switched to system suddenly and the motor-side pressure has pressure impact when rail of the pump-side is switched. To address these problems, this paper proposes a compound control strategy of feedforward compensation control with Fuzzy-PID to improve the controllability of the multi-level pressure source system. A test rig of the pump motor energy transfer unit is built and the controllability of compound controller and PID controller are compared. The experiment results show that, compared with the traditional PID, the adjustment time and the pressure impact are reduced by 20% and 25% with the proposed compound control strategy. Therefore, the presented compound control strategy can be used to improve starting performance and robustness of the pump motor energy transfer unit control system.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
Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cor...Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cores and cannot guide the development of deep oil and gas resources on Earth. The fundamental reason is the lack of temperature and pressure control in in-situ coring environments. In this paper, a pressure control method of a coring device is studied. The theory and method of deep intelligent temperature-pressure coupling control are innovatively proposed, and a multifield coupling dynamic sealing model is established. The optimal cardinality three term PID (Proportional-Integral-Differential) intelligent control algorithm of pressure system is developed. The temperature-pressure characteristic of the gas-liquid two-phase cavity is analyzed, and the pressure intelligent control is carried out based on three term PID control algorithms. An in-situ condition-preserved coring (ICP-Coring) device is developed, and an intelligent control system for the temperature and pressure of the coring device is designed and verified by experiments. The results show that the temperature-pressure coupling control system can effectively realize stable sealing under temperature-pressure fields of 140 MPa and 150 °C. The temperature-pressure coupling control method can accurately realize a constant pressure inside the coring device. The maximum working pressure is 140 MPa, and the effective pressure compensation range is 20 MPa. The numerical simulation experiment of pressure system control algorithm is carried out, and the optimal cardinality and three term coefficients are obtained. The pressure steady-state error is less than 0.01%. The method of temperature-pressure coupling control has guiding significance for coring device research, and is also the basis for temperature-pressure decoupling control in ICP-Coring.展开更多
In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductanc...In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductance and resistance.The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil,which affects the control precision of coil current.First,considering the heat dissipation mode of coil,the coil temperature model is established from the perspective of heat conduction,and a temperature compensation algorithm for hydraulic system pressure control is put forward.Then the hardware-in-the-loop testbed is set up by using the dSPACE platform,carrying out wheel cylinder pressurization tests with inlet valve fully opened at-40℃ and 20℃,and testing the actual pressure of wheel cylinder with the target pressures at-40℃ and 6 000 kPa/s(pressurization rate).The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure.After the correction,the pressure difference is less than 500 kPa,which can meet the control accuracy requirements of solenoid valve,enriching the linear control characteristic of solenoid valve.展开更多
A pressurizer is one of important equipment in a pressurized water reactor plant. It is used to maintain the pressure of primary coolant within allowed range because the sharp change of coolant pressure affects the se...A pressurizer is one of important equipment in a pressurized water reactor plant. It is used to maintain the pressure of primary coolant within allowed range because the sharp change of coolant pressure affects the security of reactor, therefor, the study of pressurizer’s pressure control methods is very important. In this paper, an adaptive fuzzy controller is presented for pressure control of a presurizer in a nuclear power plant. The controller can on-line tune fuzzy control rules and parameters by self-learning in the actual control process, which possesses the way of thinking like human to make a decision. The simulation results for a pressurized water reactor plant show that the adaptive fuzzy controller has optimum and intelligent characteristics, which prove the controller is effective.展开更多
It is very important to maintain the level of mean arterial pressure （MAP）. The MAP control is applied in many clinical situations, including limiting bleeding during cardiac surgery and promoting healing for patien...It is very important to maintain the level of mean arterial pressure （MAP）. The MAP control is applied in many clinical situations, including limiting bleeding during cardiac surgery and promoting healing for patient＇ s post-surgery. This paper presents a fuzzy controller-based multiple-model adaptive control system for postoperative blood pressure management. Multiple-model adaptive control （MMAC） algorithm is used to identify the patient model, and it is a feasible system identification method even in the presence of large noise. Fuzzy control （FC） method is used to design controller bank. Each fuzzy controller in the controller bank is in fact a nonlinear proportional-integral （PI） controller,whose proportional gain and integral gain are adjusted continuously according to error and rate of change of error of the plant output, resulting in better dynamic and stable control performance than the regular PI controller, especially when a nonlinear process is involved. For demonstration, a nonlinear, pulsatile-flow patient model is used for simulation, and the results show that the adaptive control system can effectively handle the changes in patient＇s dynamics and provide satisfactory performance in regulation of blood pressure of hypertension patients.展开更多
Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure...Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure and flow rates is valuable to optimize daily monitoring of the cardiovascular system for high-risk patients as well as to set a safe physical exercise intensity for better quality of life.In this study,we constructed an in vivo stress model for a human carotid bifurcation with atherosclerotic plaque,and analyzed the effects of blood pressure,flow rates,plaque stiffness,and stenosis on the elastic stress and fluid viscous stress around the plaque.According to the maximum values of the mechanical stress,we define a risk index to predict the risk level of plaque rupture under different exercise intensities.For a carotid bifurcation where the blood flow divides,the results suggest that the stenosis ratio determines the ratio of the contributions of elastic shear stress and viscous shear stress to plaque rupture.A n increase of the plaque stiffness enhances the maximum elastic shear stress in the plaque,indicating that a high-stiffness plaque is more prone to rupture for given stenosis ratio.High stress co-localization at the shoulder of plaques agrees with the region of plaque injury in clinical observations.It is demonstrated that,due to the stress-shield effect,the rupture risk of a high-stiffness plaque tends to decrease under high-stenosis conditions,suggesting the existence of a specific stenosis corresponding to the maximum risk.This study may help to complement risk stratification of vulnerable plaques in clinical practice and provides a stenosis mechanical property-specific guide for blood pressure control in cardiovascular health management.展开更多
Selection of aptamers with high affinity and good specificity requires multiple rounds of alternating steps of separation and PCR amplification.Herein,we proposed a novel high-efficiency aptamers picking strategy:One-...Selection of aptamers with high affinity and good specificity requires multiple rounds of alternating steps of separation and PCR amplification.Herein,we proposed a novel high-efficiency aptamers picking strategy:One-round pressure controllable selection(OPCS).OPCS integrates four types of screening superiority,high-efficiency separation,one-round selection and PCR amplification,synchronous negative selection and targets competition.The controllable screening pressure can be achieved through two approaches,balanced competition by the regulation of protein concentration,and dominant competition by introducing a predatory protein with high concentration.In OPCS process,two proteins were co-incubated with one ssDNA library,and each protein bound its favorable sequences specifically and formed protein-ss D NA complex re spectively.Meanwhile,one protein could supply/sufferthe picking pressure of affinity and specificity to/from another,which eliminated weakly bound or unbound sequences for each other.Two complexes could be separated and collected conveniently,and aptamers for two proteins obtained synchronously with high affinity and good specificity.This strategy not only provides a more effective way for aptamers selection,but shows great potential in other ligands or drugs selection.展开更多
A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of ...A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition,the geological condition is time-varying.Due to the complex load characteristics of rock or soil,the feeding velocity of TC is related to geological conditions.What is worse,its dynamic model is subjected to uncertainties and its function is unknown.To deal with the particular characteristics of CFS,a novel adaptive fuzzy integral sliding mode control(AFISMC) was designed for feeding pressure control of CFS,which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller.The AFISMC feeding pressure controller is synthesized using the backstepping technique.The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system,integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory.Experiments are conducted on a TC test bench with the AFISMC under different operating conditions.The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ?0.3 MPa.展开更多
This paper presents a technique for controlling the pressure of a molten metal when using a new type of iron casting method called sand mold press casting to realize high productivity and obtain high-quality products....This paper presents a technique for controlling the pressure of a molten metal when using a new type of iron casting method called sand mold press casting to realize high productivity and obtain high-quality products.The past test results using this method showed a casting yield of 90% to 95%,while conventional methods only show a casting yield of 60% to 70%.Although the press casting method does not require a sprue cup or runner channel casting defects such as metal penetration are often caused by the high pressure in the high-velocity pressing part of this casting process.Therefore,we proposed a pressure control method with a mathematical model of molten metal pressure,and with it we achieved experimental confirmation of the successful production of brake drums at different pressing temperatures.Results show that the proposed pressing control method can realize sound,penetration-free casting production.However,the theoretical analysis and design of this pressing process had not previously been studied sufficiently,and therefore this paper presents the theoretical design algorithm for the process as well as its experimental confirmation.展开更多
Control design is important for PEMFC （proton exchange membrane fuel cell） distributed power generator to satisfy user requirement for safe and stable operation. For a complex multi-variable dynamic system, a dynami...Control design is important for PEMFC （proton exchange membrane fuel cell） distributed power generator to satisfy user requirement for safe and stable operation. For a complex multi-variable dynamic system, a dynamic simulation model is first established. In view of close coupling and non-linear relationships between variables, the intelligent auto-adapted PI decoupling control method is used. From the simulation results it is found that, by bringing quadratic performance index in the single neuron, constructing adaptive PI controller, and adjusting gas flow rates through the second pressure relief valve and air compressor coordinately, both anode and cathode pressures can be maintained at ideal levels.展开更多
基金supported by grant 2011BAI11B01 from the Projects in the Chinese National Science and Technology Pillar Program during the 12th Five-year Plan Periodby grant 2017-I2M-1-004 from the Chinese Academy of Medical Science Innovation Fund for Medical Sciencesby the Major science and technology special plan project of Yunnan Province (202302AA310045)。
文摘Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and healthy lifestyle index (HLI)with BP control among hypertension patients is seldom reported,which needs to provide more evidence by prospective intervention studies.We examined the association of antihypertensive medication use and HLI with BP control among employees with hypertension in China based on a workplace-based multicomponent intervention program.Methods Between January 2013 and December 2014,a cluster randomized clinical trial of a workplace-based multicomponent intervention program was conducted in 60 workplaces across 20 urban areas in China.Workplaces were randomly divided into intervention (n=40) and control (n=20) groups.Basic information on employees at each workplace was collected by trained professionals,including sociodemographic characteristics,medical history,family history,lifestyle behaviors,medication status and physical measurements.After baseline,the intervention group received a 2-year intervention to achieve BP control,which included:(1) a workplace wellness program for all employees;(2) a guidelines-oriented hypertension management protocol.HLI including nonsmoking,nondrinking,adequate physical activity,weight within reference range and balanced diet,were coded on a 5-point scale (range:0-5,with higher score indicating a healthier lifestyle).Antihypertensive medication use was defined as taking drug within the last 2 weeks.Changes in HLI,antihypertensive medication use and BP control from baseline to 24 months were measured after the intervention.Results Overall,4655 employees were included (age:46.3±7.6 years,men:3547 (82.3%)).After 24 months of the intervention,there was a significant improvement in lifestyle[smoking (OR=0.65,95%CI:0.43-0.99;P=0.045),drinking (OR=0.52,95%CI:0.40-0.68;P<0.001),regular exercise (OR=3.10,95%CI:2.53-3.78;P<0.001),excessive intake of fatty food (OR=0.17,95%CI:0.06-0.52;P=0.002),restrictive use of salt (OR=0.26,95%CI:0.12-0.56;P=0.001)].Compare to employees with a deteriorating lifestyle after the intervention,those with an improved lifestyle had a higher BP control.In the intervention group,compared with employees not using antihypertensive medication,those who consistent used (OR=2.34;95%CI:1.16-4.72;P=0.017) or changed from not using to using antihypertensive medication (OR=2.24;95%CI:1.08-4.62;P=0.030) had higher BP control.Compared with those having lower HLI,participants with a same (OR=1.38;95%CI:0.99-1.93;P=0.056) or high (OR=1.79;95%CI:1.27~2.53;P<0.001) HLI had higher BP control.Those who used antihypertensive medication and had a high HLI had the highest BP control (OR=1.88;95%CI:1.32-2.67,P<0.001).Subgroup analysis also showed the consistent effect as the above.Conclusion These findings suggest that adherence to antihypertensive medication treatment and healthy lifestyle were associated with a significant improvement in BP control among employees with hypertension.
基金the Sichuan Provincial Key R&D Program(Regional Innovation Coop-eration Project 2025YFHZ0306)Open Fund(PLN 2022-46)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)Special Support for Sichuan Postdoctoral Research Projects.
文摘With the growing demand for offshore energy,deepwater drilling has become a vital technology in petroleum engineering.However,conventional drilling systems often face limitations such as delayed bottomhole pressure response and low control precision,particularly under narrow pressure window and complex formation conditions.To address these challenges,Dual-layer Pipe dual-gradient drilling(DGD)technology has been introduced,utilizing a dual-pipe structure and downhole lift pumps to extend the pressure control range.Despite these advantages,current DGD systems lack fast and precise bottomhole pressure control due to their reliance on indirect flow-based methods.This study proposes a bottomhole pressure control method based on backpressure regulation using a hybrid fuzzy-PID control strategy.A dynamic pressure calculation model is developed for the Dual-layer Pipe DGD system,incorporating coupling among choke valve opening,surface backpressure,and bottomhole pressure.The fuzzy-PID controller adjusts valve operation in real-time based on pressure deviation and its rate of change,improving response speed and control accuracy.Simulink-based simulations demonstrate that the proposed system achieves rapid pressure regulation with an overshoot below 5%and steady-state error under 0.12%.Compared to conventional PID control,the fuzzy-PID system shows superior adaptability to pressure variations.This research enhances the theoretical foundation of backpressure control in deepwater DGD operations and provides a practical approach for improving safety and efficiency in complex drilling environments.
文摘A turbine design method based on pressure controlled vortex design （PCVD） is presented to design a small-size turbine stage. Contrary to the conventional controlled vortex design （CVD） method, the main objective of PCVD is to control the axial velocity and radial pressure in the sta- tor rotor gap. Through controlling axial velocity, the PCVD establishes a direct tie to meridional stream surface. Thus stream surface variation is induced, resulting in a large secondary flow vortex covering the full blade passage in the respective stator and rotor. This secondary flow vortex could be dedicated to control the secondary flow mitigation and migration. Through radial pressure, the PCVD is also associated with the macroscopic driving force of fluid motion. So the better benefit of CVD can be achieved. The core concept behind PCVD is to mainly control the spanwise pressure gradient by altering profile loading at various spanwise locations. Therefore not only the local pro- file lift is affected, but also the resulting throat widths, stage reaction degree, and massflow rate are altered or redistributed respectively. With the PCVD method, the global stage efficiency is increased successfully while the mass flow rate keeps constant. Additionally there is no endwall shape optimization, stacking optimization, or pitch/chord variations, concentrating solely on varying blade profile deflections and stagger.
基金supported by National Natural Science Foundation of China(No.41576108 and No.41605006)Natural Science Foundation project of Shandong Province(No.ZR2016DB26).
文摘Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation situation,divergence and vertical velocity field,and the vertical profile of temperature and humidity are synthesized and analyzed.The basic characteristics of the circulation and physical field of sea fog under low pressure control(L type sea fog)are obtained,and the results are compared with the sea fog under the control of high pressure(H type sea fog):a)L type sea fogs potential height anomaly disturbance is mainly manifested in the low layer,and its average value is-65.66 gpm,gradually weakening upward;b)L type sea fogs inversion structure is weaker than H type sea fogs when it occurs,the fog layer is thicker and the high relative humidity level is high over the fog layer,while the H type sea fogs fog layer has a relatively obvious dry layer;c)L sea fog has three layers of structure at the vertical direction.The first layer 1000-950 hPa is convergence accompanied by weak rise and subsidence,the second layer 950-850 hPa is divergence accompanied by weak subsidence,and the third layer 850 to 500hPa is gradually strengthened.While there are two layer structures of the H type sea fog.1000 hPa is divergence accompanied by weak rising and sinking movement,950-500 hPa is a uniform subsidence movement.d)Probability density statistical analysis further quantified the vertical movement of L and H type sea fog and the distribution of relative humidity in each layer.These conclusions provide an important reference for forecasting the sea fog in the northwest of the Yellow Sea under the condition of low pressure circulation in summer.
文摘This paper describes a supervisory hierarchical fuzzy controller （SHFC） for regulating pressure in a real-time pilot pressure control system. The input scaling factor tuning of a direct expert controller is made using the error and process input parameters in a closed loop system in order to obtain better controller performance for set-point change and load disturbances. This on-line tuning method reduces operator involvement and enhances the controller performance to a wide operating range. The hierarchical control scheme consists of an intelligent upper level supervisory fuzzy controller and a lower level direct fuzzy controller. The upper level controller provides a mechanism to the main goal of the system and the lower level controller delivers the solutions to a particular situation. The control algorithm for the proposed scheme has been developed and tested using an ARM7 microcontroller-based embedded target board for a nonlinear pressure process having dead time. To demonstrate the effectiveness, the results of the proposed hierarchical controller, fuzzy controller and conventional proportional-integral （PI） controller are analyzed. The results prove that the SHFC performance is better in terms of stability and robustness than the conventional control methods.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(No.51827901&No.52274133)the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)the Shenzhen National Science Fund for Distinguished Young Scholars(RCJC20210706091948015).
文摘In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of the pressure controller valve cover in different medium environments is unclear,interference between the valve cover and inner pipe may occur and negatively affect the IPP-Coring success rate.To address this issue,we conducted a series of indoor experiments employing a high-speed camera to gain greater insights into the valve cover rotation behavior in different medium environments,e.g.,air,water,and simulated drilling fluids.The results indicated that the variation in the valve cover rotation angle in the air and fluid environments can be described by a one-phase exponential decay function with a constant time parameter and by biphasic dose response function,respectively.The rotation behavior in the fluid environments exhibited distinct elastic and gravitational acceleration zones.In the fluid environments,the density clearly impacted the valve cover closing time and rotation behavior,whereas the effect of viscosity was very slight.This can be attributed to the negligible influence of the fluid viscosity on the drag coefficient found in this study;meanwhile,the density can increase the buoyancy and the time period during which the valve cover experienced a high drag coefficient.Considering these results,control schemes for the valve cover rotation behavior during IPP-Coring were proposed for different layers and geological conditions in which the different drilling fluids should be used,e.g.,the use of a high-density valve cover in high-pore pressure layers.
基金The Project of the National Ministry of Industry and Information Technology[2020-0103-3-1-1]The Project of Beijing Science and technology“capital characteristics”[Z181100001718007]。
文摘Objective Current clinical evidence on the effects of home blood pressure telemonitoring(HBPT)on improving blood pressure control comes entirely from developed countries.Thus,we performed this randomized controlled trial to evaluate whether HBPT plus support(patient education and clinician remote hypertension management)improves blood pressure control more than usual care(UC)in the Chinese population.Methods This single-center,randomized controlled study was conducted in Beijing,China.Patients aged 30-75 years were eligible for enrolment if they had blood pressure[systolic(SBP)≥140 mmHg and/or diastolic(DBP)≥90 mmHg;or SBP≥130 mmHg and/or DBP≥80 mmHg with diabetes].We recruited 190 patients randomized to either the HBPT or the UC groups for 12 weeks.The primary endpoints were blood pressure reduction and the proportion of patients achieving the target blood pressure.Results Totally,172 patients completed the study,the HBPT plus support group(n=84),and the UC group(n=88).Patients in the plus support group showed a greater reduction in mean ambulatory blood pressure than those in the UC group.The plus support group had a significantly higher proportion of patients who achieved the target blood pressure and maintained a dipper blood pressure pattern at the12th week of follow-up.Additionally,the patients in the plus support group showed lower blood pressure variability and higher drug adherence than those in the UC group.Conclusion HBPT plus additional support results in greater blood pressure reduction,better blood pressure control,a higher proportion of dipper blood pressure patterns,lower blood pressure variability,and higher drug adherence than UC.The development of telemedicine may be the cornerstone of hypertension management in primary care.
基金supported by National Natural Science Foundation of China (Grant No. 50775199)National Hi-tech Research and Development Program of China (863 Program,Grant No. 2008AA042703)
文摘Water-assisted injection molding（WAIM）,a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving,short cooling circle time and high quality of products.Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM.However,the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system.In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM,the proportional pressure control of the WAIM system is investigated both numerically and experimentally.A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment,the load characteristics and the nonlinearities of water hydraulic system are both considered,then the main factors affecting the injecting pressure and load flow rate are extensively studied.Meanwhile,an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance.In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene（ABS） parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation.The good coincidence between experiment and simulation shows that the AMEsim model is accurate,and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system.The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.
文摘The performance of the designed digital electro-pneumatic cabin pressure control system for the cabin pressure schedule of transport aircraft is investigated.For the purpose of this study,an experimental setup consisting of a simulated hermetic cabin and altitude simulation chamber is configured for cabin pressure control system operation.A series of experimental tests are executed to evaluate the performance of the cabin pressure control system.The parameters of the PID controller are optimized.In the optimization process,the variation regularity of the rate of cabin pressure change under various conditions is considered.An approach to prioritize the control of the rate of change of cabin pressure based on the flight status model is proposed and verified experimentally.The experimental results indicate that the proposed approach can be adopted for the designed digital electro-pneumatic cabin pressure control system to obtain a better cabin pressure schedule and rate of cabin pressure change.
基金Supported by the National Natural Science Foundation of China(No.51575471)the Key Project of Science and Technology Plan of Higher Education of Hebei Education Department(No.ZD2017077)
文摘Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer unit is usually equipped. However, the pump motor energy transfer has the characteristics of poor starting and low response, which cause long time of pressure adjustment and large pressure jitter when the transformer is switched to system suddenly and the motor-side pressure has pressure impact when rail of the pump-side is switched. To address these problems, this paper proposes a compound control strategy of feedforward compensation control with Fuzzy-PID to improve the controllability of the multi-level pressure source system. A test rig of the pump motor energy transfer unit is built and the controllability of compound controller and PID controller are compared. The experiment results show that, compared with the traditional PID, the adjustment time and the pressure impact are reduced by 20% and 25% with the proposed compound control strategy. Therefore, the presented compound control strategy can be used to improve starting performance and robustness of the pump motor energy transfer unit control system.
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.
基金supported by the National Natural Science Foundation of China(grant numbers 51827901,51805340)funded by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)Shenzhen Basic Research Program(General Program)(No.JCYJ20190808153416970).
文摘Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cores and cannot guide the development of deep oil and gas resources on Earth. The fundamental reason is the lack of temperature and pressure control in in-situ coring environments. In this paper, a pressure control method of a coring device is studied. The theory and method of deep intelligent temperature-pressure coupling control are innovatively proposed, and a multifield coupling dynamic sealing model is established. The optimal cardinality three term PID (Proportional-Integral-Differential) intelligent control algorithm of pressure system is developed. The temperature-pressure characteristic of the gas-liquid two-phase cavity is analyzed, and the pressure intelligent control is carried out based on three term PID control algorithms. An in-situ condition-preserved coring (ICP-Coring) device is developed, and an intelligent control system for the temperature and pressure of the coring device is designed and verified by experiments. The results show that the temperature-pressure coupling control system can effectively realize stable sealing under temperature-pressure fields of 140 MPa and 150 °C. The temperature-pressure coupling control method can accurately realize a constant pressure inside the coring device. The maximum working pressure is 140 MPa, and the effective pressure compensation range is 20 MPa. The numerical simulation experiment of pressure system control algorithm is carried out, and the optimal cardinality and three term coefficients are obtained. The pressure steady-state error is less than 0.01%. The method of temperature-pressure coupling control has guiding significance for coring device research, and is also the basis for temperature-pressure decoupling control in ICP-Coring.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2012AA110903)Jilin Key Scientific and Technological Project(20170204085GX)Jilin Industrial Technology Innovation Strategic Alliance Program(20150309013GX)
文摘In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductance and resistance.The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil,which affects the control precision of coil current.First,considering the heat dissipation mode of coil,the coil temperature model is established from the perspective of heat conduction,and a temperature compensation algorithm for hydraulic system pressure control is put forward.Then the hardware-in-the-loop testbed is set up by using the dSPACE platform,carrying out wheel cylinder pressurization tests with inlet valve fully opened at-40℃ and 20℃,and testing the actual pressure of wheel cylinder with the target pressures at-40℃ and 6 000 kPa/s(pressurization rate).The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure.After the correction,the pressure difference is less than 500 kPa,which can meet the control accuracy requirements of solenoid valve,enriching the linear control characteristic of solenoid valve.
文摘A pressurizer is one of important equipment in a pressurized water reactor plant. It is used to maintain the pressure of primary coolant within allowed range because the sharp change of coolant pressure affects the security of reactor, therefor, the study of pressurizer’s pressure control methods is very important. In this paper, an adaptive fuzzy controller is presented for pressure control of a presurizer in a nuclear power plant. The controller can on-line tune fuzzy control rules and parameters by self-learning in the actual control process, which possesses the way of thinking like human to make a decision. The simulation results for a pressurized water reactor plant show that the adaptive fuzzy controller has optimum and intelligent characteristics, which prove the controller is effective.
文摘It is very important to maintain the level of mean arterial pressure （MAP）. The MAP control is applied in many clinical situations, including limiting bleeding during cardiac surgery and promoting healing for patient＇ s post-surgery. This paper presents a fuzzy controller-based multiple-model adaptive control system for postoperative blood pressure management. Multiple-model adaptive control （MMAC） algorithm is used to identify the patient model, and it is a feasible system identification method even in the presence of large noise. Fuzzy control （FC） method is used to design controller bank. Each fuzzy controller in the controller bank is in fact a nonlinear proportional-integral （PI） controller,whose proportional gain and integral gain are adjusted continuously according to error and rate of change of error of the plant output, resulting in better dynamic and stable control performance than the regular PI controller, especially when a nonlinear process is involved. For demonstration, a nonlinear, pulsatile-flow patient model is used for simulation, and the results show that the adaptive control system can effectively handle the changes in patient＇s dynamics and provide satisfactory performance in regulation of blood pressure of hypertension patients.
基金This work was supported by the National Key R&D Program of China(Grant 2017YFE0117100)the National Natural Science Foundation of China(Grants 11872040 and 11232010)+1 种基金the Outstanding Clinical Discipline Project of Shanghai Pudong(Grant PWYgy-2018-08)the Science and Technology Commission of Shanghai Municipality(Grant 18ZR1433900).
文摘Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure and flow rates is valuable to optimize daily monitoring of the cardiovascular system for high-risk patients as well as to set a safe physical exercise intensity for better quality of life.In this study,we constructed an in vivo stress model for a human carotid bifurcation with atherosclerotic plaque,and analyzed the effects of blood pressure,flow rates,plaque stiffness,and stenosis on the elastic stress and fluid viscous stress around the plaque.According to the maximum values of the mechanical stress,we define a risk index to predict the risk level of plaque rupture under different exercise intensities.For a carotid bifurcation where the blood flow divides,the results suggest that the stenosis ratio determines the ratio of the contributions of elastic shear stress and viscous shear stress to plaque rupture.A n increase of the plaque stiffness enhances the maximum elastic shear stress in the plaque,indicating that a high-stiffness plaque is more prone to rupture for given stenosis ratio.High stress co-localization at the shoulder of plaques agrees with the region of plaque injury in clinical observations.It is demonstrated that,due to the stress-shield effect,the rupture risk of a high-stiffness plaque tends to decrease under high-stenosis conditions,suggesting the existence of a specific stenosis corresponding to the maximum risk.This study may help to complement risk stratification of vulnerable plaques in clinical practice and provides a stenosis mechanical property-specific guide for blood pressure control in cardiovascular health management.
基金the National Natural Science Foundation of China(Nos.21675012,21874010 and 21827810)the Young Elite Scientist Sponsorship Program of Beijing Association for Science and Technology。
文摘Selection of aptamers with high affinity and good specificity requires multiple rounds of alternating steps of separation and PCR amplification.Herein,we proposed a novel high-efficiency aptamers picking strategy:One-round pressure controllable selection(OPCS).OPCS integrates four types of screening superiority,high-efficiency separation,one-round selection and PCR amplification,synchronous negative selection and targets competition.The controllable screening pressure can be achieved through two approaches,balanced competition by the regulation of protein concentration,and dominant competition by introducing a predatory protein with high concentration.In OPCS process,two proteins were co-incubated with one ssDNA library,and each protein bound its favorable sequences specifically and formed protein-ss D NA complex re spectively.Meanwhile,one protein could supply/sufferthe picking pressure of affinity and specificity to/from another,which eliminated weakly bound or unbound sequences for each other.Two complexes could be separated and collected conveniently,and aptamers for two proteins obtained synchronously with high affinity and good specificity.This strategy not only provides a more effective way for aptamers selection,but shows great potential in other ligands or drugs selection.
基金Project(2012AA041801)supported by the High-tech Research and Development Program of China
文摘A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition,the geological condition is time-varying.Due to the complex load characteristics of rock or soil,the feeding velocity of TC is related to geological conditions.What is worse,its dynamic model is subjected to uncertainties and its function is unknown.To deal with the particular characteristics of CFS,a novel adaptive fuzzy integral sliding mode control(AFISMC) was designed for feeding pressure control of CFS,which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller.The AFISMC feeding pressure controller is synthesized using the backstepping technique.The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system,integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory.Experiments are conducted on a TC test bench with the AFISMC under different operating conditions.The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ?0.3 MPa.
文摘This paper presents a technique for controlling the pressure of a molten metal when using a new type of iron casting method called sand mold press casting to realize high productivity and obtain high-quality products.The past test results using this method showed a casting yield of 90% to 95%,while conventional methods only show a casting yield of 60% to 70%.Although the press casting method does not require a sprue cup or runner channel casting defects such as metal penetration are often caused by the high pressure in the high-velocity pressing part of this casting process.Therefore,we proposed a pressure control method with a mathematical model of molten metal pressure,and with it we achieved experimental confirmation of the successful production of brake drums at different pressing temperatures.Results show that the proposed pressing control method can realize sound,penetration-free casting production.However,the theoretical analysis and design of this pressing process had not previously been studied sufficiently,and therefore this paper presents the theoretical design algorithm for the process as well as its experimental confirmation.
基金Project supported by National High-Technology Research andDevelopment Program of China (Grant No .2002AA517020)
文摘Control design is important for PEMFC （proton exchange membrane fuel cell） distributed power generator to satisfy user requirement for safe and stable operation. For a complex multi-variable dynamic system, a dynamic simulation model is first established. In view of close coupling and non-linear relationships between variables, the intelligent auto-adapted PI decoupling control method is used. From the simulation results it is found that, by bringing quadratic performance index in the single neuron, constructing adaptive PI controller, and adjusting gas flow rates through the second pressure relief valve and air compressor coordinately, both anode and cathode pressures can be maintained at ideal levels.
