Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to ...Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.展开更多
The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variat...The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment, The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.展开更多
A linear quadric (LQ) optimal speed control algorithm is proposed for the speed control of a pump controlled motor hydraulic system. The control theme consists of optimal state feedback and disturbing compensation bas...A linear quadric (LQ) optimal speed control algorithm is proposed for the speed control of a pump controlled motor hydraulic system. The control theme consists of optimal state feedback and disturbing compensation based on observation. The optimal state feedback bases on LQ cost function. The disturbing compensation is realized through reconstructing the state of load torque. A series of simulation are performed, and the results show that the control performance is satisfactory and can be maintained under changes of load torque.展开更多
Background Ion pump control system of HIRFL is designed based on the real-time distributed control software,EPICS.The hardware architecture,communication principle,database design and interlock design are introduced a...Background Ion pump control system of HIRFL is designed based on the real-time distributed control software,EPICS.The hardware architecture,communication principle,database design and interlock design are introduced and elaborated in the paper.Methods PLC has been adopted to realize functions such as control monitoring and data communication.Interlock protect ion has been designed for ion pump control system to prevent damaging from high voltage.Results The test results show that the system has fast response function and high-speed data processing during the beam running and tuning.The response time of the system could reach 100 ms,the rate of data acquisition reaches to 10 time/s and the interlock protection time less than 40 ms.Conclusion The reliable and stable long-term operation of the vacuum system indicates that the performance has been constantly improved with the continuous optimization of the ion pump control system.展开更多
This paper simulated the optimal refrigerant charge inventory of a refrigeration system in air-conditioning operation and heat-pump operation respectively,and studied the refrigerant control strategies in this system....This paper simulated the optimal refrigerant charge inventory of a refrigeration system in air-conditioning operation and heat-pump operation respectively,and studied the refrigerant control strategies in this system.The void fraction in two-phase fluid region was calculated by Harms model.And based on distributed parameter model and Harms model,the refrigerant charge inventory in condenser and evaporator were calculated and analyzed in air-conditioning conditions and heat-pump conditions,respectively.The calculating results of different refrigerant mass between refrigeration and heating conditions indicate that the optimal refrigerant charge inventory in heat-pump conditions is lower than that in air-conditioning conditions.To avoid the decrease of COP due to the surplus refrigerant in heating conditions,we introduced the liquid reservoir control method and associate capillary control method.Both of them could increase the heating capacity of the air-source heat pump.The difference of optimal refrigerant charge inventory in air-conditioning and heat-pump system can be controlled by the liquid reservoir or the associate capillary.展开更多
The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation...The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation, the thermal design of ECU for electronic unit pump （EUP） fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time展开更多
The variable pump displacement and variable motor speed electro-hydrostatic actuator(EHA),one of the three types of EHAs,has advantages such as short response time,flexible speed regulation,and high efficiency.However...The variable pump displacement and variable motor speed electro-hydrostatic actuator(EHA),one of the three types of EHAs,has advantages such as short response time,flexible speed regulation,and high efficiency.However,the nonlinearity of its double-input single-output system poses a great challenge for system control.This study proposes a novel EHA with adaptive pump displacement and variable motor speed(EHA-APVM).A closed-loop position is realized using a servomotor.Moreover,the displacement varies with the system pressure;thus,the EHA-APVM is a single-input and single-output system.Firstly,the working principles of the EHA-APVM and the pump used in the system are introduced.Secondly,a nonlinear mathematical model of the proposed EHA-APVM control system is established,and a feedback back-stepping(FBBS)control algorithm is introduced to transform the complex nonlinear system into a linear system on the basis of the back-stepping control theory.Finally,simulation results prove that the EHA-APVM has a quick response and high robustness to variations of the load and the pump displacement.In this work,the size and weight of the motor are significantly reduced because the maximum power requirement is reduced,which is very beneficial for using the actuator in airborne equipment.展开更多
Gastrin is a linear peptide hormone which is secreted mostly in the stomach pyloric antrum G cells. Although the main role of this hormone is the promotion of the secretion of gastric acid from the stomach parietal ce...Gastrin is a linear peptide hormone which is secreted mostly in the stomach pyloric antrum G cells. Although the main role of this hormone is the promotion of the secretion of gastric acid from the stomach parietal cells, gastrin can also behave as a growth factor and stimulate gastric cell proliferation. It is also reported that gastrin promotes β cell neogenesis in the pancreatic ductal complex, modest pancreatic β cell replication, and improvement of glucose tolerance in animal models, in which the remodeling of pancreatic tissues is promoted. These findings suggest the possibility that gastrin has the potential to promote an increase of β cell mass in pancreas, and therefore that gastrin may improve glucose tolerance. Proton pump inhibitors(PPIs) are wildly used clinically for the therapy of gastro-esophageal reflex disease, gastritis due to excess stomach acid, and gastric ulcers. PPIs indirectly elevate serum gastrin levels via a negative feedback effect. Recent evidence has revealed the beneficial effect of PPIs on glycemic control especially in patients with type 2 diabetes mellitus(T2DM), probably via the elevation of the levels of serum gastrin, although the detailed mechanism remains unclear. In addition, the beneficial effects of a combination therapy of gastrin or a PPI with a glucagon-like peptide-1 receptor agonist on glycemic control in animal models have been demonstrated. Although PPIs may be possible candidates for a new approach in the therapy of diabetes, a prospective, longterm, randomized, double-blind, placebo-controlled study is needed to establish the effect of PPIs on glycemic control in a large number of patients with T2 DM.展开更多
To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carri...To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carried out. According to the leaking property of thesystem, a speed offset principle is also proposed to eliminate the cavitation and tension caused bythe leakage and condensation of oil, which makes the system be in the same state as a valvecontrolled circuit. This principle is explained theoretically and experimentally. Further therelationship that the pressures in cylinder chambers change with load and leakage, and therelationship between biasing speed and pre-load pressures in cylinder chambers are established. Theresearch has proved that the new system has similar technique features as those of controlled withservo valves, but due to the elimination of all the throttle lose the efficiency of system can beimproved greatly.展开更多
Automatic Control of pumps is an interesting proposal to operate water pumping stations among many kinds of water pumping stations according to their functions.In this paper,our pumping station is being used for water...Automatic Control of pumps is an interesting proposal to operate water pumping stations among many kinds of water pumping stations according to their functions.In this paper,our pumping station is being used for water supply system. This paper is to introduce the idea of pump controller and the important factors that must be considering when we want to design automatic control system of water pumping stations. Then the automatic control circuit with the function of all components will be introduced.展开更多
In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tr...In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tropical fruits and energy and exergy analyses were made. Drying air temperature changed between 40 oC - 40.2 oC while drying the tropical fruits. Before the drying process in heat pump dryer, initial moisture contents were determined as 4.31 g water / g dry matter for kiwi, 1.51 g water / g dry matter for avocado and 4.71 g water / g dry matter for banana. Then tropical fruits were dried separately in heat pump dryer. Drying air temperature was kept unchanged with the error of +0.2 oC. Drying air velocity changed between 0.3 and 0.4 m/s in a period of 310 min. COPws of the heat pump dryer was calculated as 2.49 for kiwi, 2.47 for banana and 2.41 for avocado during the experiments. EUR changed between 13 % and 28 % for kiwi, 18% and 33% for avocado and 13% and 42% for banana in heat pump dryer.展开更多
In order to compromise the conflicts between control accuracy and system efficiency of conventional electro-hydraulic servo systems,a novel pump-valve coordinated electro-hydraulic servo system was designed and a corr...In order to compromise the conflicts between control accuracy and system efficiency of conventional electro-hydraulic servo systems,a novel pump-valve coordinated electro-hydraulic servo system was designed and a corresponding control strategy was proposed.The system was constituted of a pumpcontrolled part and a valve-controlled part,the pump controlled part is used to adjust the flow rate of oil source and the valve controlled part is used to complete the position tracking control of the hydraulic cylinder.Based on the system characteristics,a load flow grey prediction method was adopted in the pump controlled part to reduce the system overflow losses,and an adaptive robust control method was adopted in the valve controlled part to eliminate the effect of system nonlinearity and parametric uncertainties due to variable hydraulic parameters and system loads on the control precision.The experimental results validated that the adopted control strategy increased the system efficiency obviously with guaranteed high control accuracy.展开更多
The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the ...The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality （LMI）. These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.展开更多
We study the controlling of the Goos-Hanchen （GH） shifts in reflected and transmitted light beams in the triple coupled InGaAs/GaAs quantum dot （QD） nanostructures with electron tunneling and incoherent pumping fi...We study the controlling of the Goos-Hanchen （GH） shifts in reflected and transmitted light beams in the triple coupled InGaAs/GaAs quantum dot （QD） nanostructures with electron tunneling and incoherent pumping field. It is shown that the lateral shift can become either large negative or large positive, which can be controlled by the electron tunneling and the rate of incoherent pump field in different incident angles. It is also demonstrated that the properties of the OH shifts are strongly dependent on the probe absorption beam of the intracavity medium due to the switching from superluminal light propagation to subluminal behavior or vice versa. Our suggested system can be considered as a new theoretical method for developing a new nano-optoelectronic sensor.展开更多
Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and ...Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and across production fields, which could have a major impact on fertilizer management strategies. Therefore, uniform application of a fertilizer over the entire field can be both costly and environmentally unsound. Due to their rugged and fool-proof design, crankshaft type piston pumps are widely used in agriculture. The on-the-go outlet flow of these pumps can only be varied by changing the drive shaft speed for each pump stroke setting. But only a limited range of flow rates can be achieved by changing the drive shaft speed. There is a need for an electronic controller, which can adjust the pump stroke on-the-go, for real-time, variable-rate application of crop nutrients. The Clemson “Electro-me-chanical controller for adjusting pump stroke on-the-go” was designed to replace the current manual stroke adjustment system on positive displacement piston pumps. This affordable system can be retrofitted on most John Blue - piston pumps for real-time adjustment of the pump stroke and can be controlled using pre-described position sequences (map-based) or real-time sensor commands (such as optical, pressure, and flow sensors) combined with fertilizer calculation algorithms. In addition, it can adjust pump stroke manually, using an eclectic dial from the tractor’s cab.展开更多
In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array vol...In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array voltage and current being used to generate the reference voltage which should be the PV panel’s operating voltage to get maximum available power. A Takagi-Sugeno (T-S) observer has been proposed and designed with non-measurable premise variables and the conditions of stability are given in terms of Linear Matrix Inequality (LMI). The simulation results show the effectiveness and robustness of the proposed method.展开更多
The performance of the electronic unit pump (EUP) diesel engine is studied, it will be used in the integrated powertrain and its multi parameters are controllable. Both the theoretical analysis and experiment research...The performance of the electronic unit pump (EUP) diesel engine is studied, it will be used in the integrated powertrain and its multi parameters are controllable. Both the theoretical analysis and experiment research are taken. A control unit for the fuel quantity and timing in crankshaft domain is designed on this basis and the engine experiment test has been done. For the constant speed camshaft driving EUP system, the fuel quantity will increase as the supply angle goes up and injection timing has no effect. The control precision can reach 1°CA. The full injection timing MAP and engine peak performance curves are made successfully.展开更多
In this paper, a mathematical model of the photovoltaic （PV） pumping system＇s main components is firstly established. Then, the design of maximum power point tracking （MPPT） stage that ensures battery charging is...In this paper, a mathematical model of the photovoltaic （PV） pumping system＇s main components is firstly established. Then, the design of maximum power point tracking （MPPT） stage that ensures battery charging is described. This work is motivated by the need of photovoltaic generator （PVG） that efficiently extracts maximum power. The PVG is a special source of energy which has nonlinear current-voltage characteristics depending on variations in temperature and solar irradiance. In order to achieve the MPPT operating goals, a special interest is focused on the variable structure sliding mode （SM） control strategy and the classic perturb and observe （P＆O） algorithm. The permanent magnet synchronous motor （PMSM） is selected as a pump driver. The field oriented control is performed as the motor drive strategy. Simulation results show a high level of efficiency, obtained with the proposed PV based pumping system. The performance comparison between SM controller and P＆O controller has been carried out to demonstrate the effectiveness of the former in drawing more energy and a fast response against irradiation disturbances.展开更多
基金The Project Supported by Doctoral Programme Foundation of Institution of Higher Education
文摘Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.
基金This project is supported by National Natural Science Foundation of China (No.50275102)Opening Foundation of State Key Lab of Fluid Power Transmission and Control of Zhejiang University, China (No.GZKF2002004).
文摘The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment, The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.
文摘A linear quadric (LQ) optimal speed control algorithm is proposed for the speed control of a pump controlled motor hydraulic system. The control theme consists of optimal state feedback and disturbing compensation based on observation. The optimal state feedback bases on LQ cost function. The disturbing compensation is realized through reconstructing the state of load torque. A series of simulation are performed, and the results show that the control performance is satisfactory and can be maintained under changes of load torque.
基金National Nature Science Foundation of China under Grant No.U1632141 and Western Light Foundation of Chinese Academy of Science under Grant No.29Y926040.
文摘Background Ion pump control system of HIRFL is designed based on the real-time distributed control software,EPICS.The hardware architecture,communication principle,database design and interlock design are introduced and elaborated in the paper.Methods PLC has been adopted to realize functions such as control monitoring and data communication.Interlock protect ion has been designed for ion pump control system to prevent damaging from high voltage.Results The test results show that the system has fast response function and high-speed data processing during the beam running and tuning.The response time of the system could reach 100 ms,the rate of data acquisition reaches to 10 time/s and the interlock protection time less than 40 ms.Conclusion The reliable and stable long-term operation of the vacuum system indicates that the performance has been constantly improved with the continuous optimization of the ion pump control system.
基金Supported by Hubei Provincial Natural Science Foundation(2008CDB363)
文摘This paper simulated the optimal refrigerant charge inventory of a refrigeration system in air-conditioning operation and heat-pump operation respectively,and studied the refrigerant control strategies in this system.The void fraction in two-phase fluid region was calculated by Harms model.And based on distributed parameter model and Harms model,the refrigerant charge inventory in condenser and evaporator were calculated and analyzed in air-conditioning conditions and heat-pump conditions,respectively.The calculating results of different refrigerant mass between refrigeration and heating conditions indicate that the optimal refrigerant charge inventory in heat-pump conditions is lower than that in air-conditioning conditions.To avoid the decrease of COP due to the surplus refrigerant in heating conditions,we introduced the liquid reservoir control method and associate capillary control method.Both of them could increase the heating capacity of the air-source heat pump.The difference of optimal refrigerant charge inventory in air-conditioning and heat-pump system can be controlled by the liquid reservoir or the associate capillary.
文摘The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation, the thermal design of ECU for electronic unit pump （EUP） fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time
基金financially supported by the National Natural Science Foundation of China(No’s.51375029 and 51775013).
文摘The variable pump displacement and variable motor speed electro-hydrostatic actuator(EHA),one of the three types of EHAs,has advantages such as short response time,flexible speed regulation,and high efficiency.However,the nonlinearity of its double-input single-output system poses a great challenge for system control.This study proposes a novel EHA with adaptive pump displacement and variable motor speed(EHA-APVM).A closed-loop position is realized using a servomotor.Moreover,the displacement varies with the system pressure;thus,the EHA-APVM is a single-input and single-output system.Firstly,the working principles of the EHA-APVM and the pump used in the system are introduced.Secondly,a nonlinear mathematical model of the proposed EHA-APVM control system is established,and a feedback back-stepping(FBBS)control algorithm is introduced to transform the complex nonlinear system into a linear system on the basis of the back-stepping control theory.Finally,simulation results prove that the EHA-APVM has a quick response and high robustness to variations of the load and the pump displacement.In this work,the size and weight of the motor are significantly reduced because the maximum power requirement is reduced,which is very beneficial for using the actuator in airborne equipment.
文摘Gastrin is a linear peptide hormone which is secreted mostly in the stomach pyloric antrum G cells. Although the main role of this hormone is the promotion of the secretion of gastric acid from the stomach parietal cells, gastrin can also behave as a growth factor and stimulate gastric cell proliferation. It is also reported that gastrin promotes β cell neogenesis in the pancreatic ductal complex, modest pancreatic β cell replication, and improvement of glucose tolerance in animal models, in which the remodeling of pancreatic tissues is promoted. These findings suggest the possibility that gastrin has the potential to promote an increase of β cell mass in pancreas, and therefore that gastrin may improve glucose tolerance. Proton pump inhibitors(PPIs) are wildly used clinically for the therapy of gastro-esophageal reflex disease, gastritis due to excess stomach acid, and gastric ulcers. PPIs indirectly elevate serum gastrin levels via a negative feedback effect. Recent evidence has revealed the beneficial effect of PPIs on glycemic control especially in patients with type 2 diabetes mellitus(T2DM), probably via the elevation of the levels of serum gastrin, although the detailed mechanism remains unclear. In addition, the beneficial effects of a combination therapy of gastrin or a PPI with a glucagon-like peptide-1 receptor agonist on glycemic control in animal models have been demonstrated. Although PPIs may be possible candidates for a new approach in the therapy of diabetes, a prospective, longterm, randomized, double-blind, placebo-controlled study is needed to establish the effect of PPIs on glycemic control in a large number of patients with T2 DM.
基金This project is supported by National Natural Science Foundation of China(No.50275102) National Foundation for Abroad Return People, China (No.2001345).
文摘To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carried out. According to the leaking property of thesystem, a speed offset principle is also proposed to eliminate the cavitation and tension caused bythe leakage and condensation of oil, which makes the system be in the same state as a valvecontrolled circuit. This principle is explained theoretically and experimentally. Further therelationship that the pressures in cylinder chambers change with load and leakage, and therelationship between biasing speed and pre-load pressures in cylinder chambers are established. Theresearch has proved that the new system has similar technique features as those of controlled withservo valves, but due to the elimination of all the throttle lose the efficiency of system can beimproved greatly.
文摘Automatic Control of pumps is an interesting proposal to operate water pumping stations among many kinds of water pumping stations according to their functions.In this paper,our pumping station is being used for water supply system. This paper is to introduce the idea of pump controller and the important factors that must be considering when we want to design automatic control system of water pumping stations. Then the automatic control circuit with the function of all components will be introduced.
文摘In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tropical fruits and energy and exergy analyses were made. Drying air temperature changed between 40 oC - 40.2 oC while drying the tropical fruits. Before the drying process in heat pump dryer, initial moisture contents were determined as 4.31 g water / g dry matter for kiwi, 1.51 g water / g dry matter for avocado and 4.71 g water / g dry matter for banana. Then tropical fruits were dried separately in heat pump dryer. Drying air temperature was kept unchanged with the error of +0.2 oC. Drying air velocity changed between 0.3 and 0.4 m/s in a period of 310 min. COPws of the heat pump dryer was calculated as 2.49 for kiwi, 2.47 for banana and 2.41 for avocado during the experiments. EUR changed between 13 % and 28 % for kiwi, 18% and 33% for avocado and 13% and 42% for banana in heat pump dryer.
基金Supported by Program for New Century Excellent Talents In University(NCET-12-0049)Beijing Natural Science Foundation(4132034)
文摘In order to compromise the conflicts between control accuracy and system efficiency of conventional electro-hydraulic servo systems,a novel pump-valve coordinated electro-hydraulic servo system was designed and a corresponding control strategy was proposed.The system was constituted of a pumpcontrolled part and a valve-controlled part,the pump controlled part is used to adjust the flow rate of oil source and the valve controlled part is used to complete the position tracking control of the hydraulic cylinder.Based on the system characteristics,a load flow grey prediction method was adopted in the pump controlled part to reduce the system overflow losses,and an adaptive robust control method was adopted in the valve controlled part to eliminate the effect of system nonlinearity and parametric uncertainties due to variable hydraulic parameters and system loads on the control precision.The experimental results validated that the adopted control strategy increased the system efficiency obviously with guaranteed high control accuracy.
文摘The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality （LMI）. These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.
文摘We study the controlling of the Goos-Hanchen （GH） shifts in reflected and transmitted light beams in the triple coupled InGaAs/GaAs quantum dot （QD） nanostructures with electron tunneling and incoherent pumping field. It is shown that the lateral shift can become either large negative or large positive, which can be controlled by the electron tunneling and the rate of incoherent pump field in different incident angles. It is also demonstrated that the properties of the OH shifts are strongly dependent on the probe absorption beam of the intracavity medium due to the switching from superluminal light propagation to subluminal behavior or vice versa. Our suggested system can be considered as a new theoretical method for developing a new nano-optoelectronic sensor.
文摘Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and across production fields, which could have a major impact on fertilizer management strategies. Therefore, uniform application of a fertilizer over the entire field can be both costly and environmentally unsound. Due to their rugged and fool-proof design, crankshaft type piston pumps are widely used in agriculture. The on-the-go outlet flow of these pumps can only be varied by changing the drive shaft speed for each pump stroke setting. But only a limited range of flow rates can be achieved by changing the drive shaft speed. There is a need for an electronic controller, which can adjust the pump stroke on-the-go, for real-time, variable-rate application of crop nutrients. The Clemson “Electro-me-chanical controller for adjusting pump stroke on-the-go” was designed to replace the current manual stroke adjustment system on positive displacement piston pumps. This affordable system can be retrofitted on most John Blue - piston pumps for real-time adjustment of the pump stroke and can be controlled using pre-described position sequences (map-based) or real-time sensor commands (such as optical, pressure, and flow sensors) combined with fertilizer calculation algorithms. In addition, it can adjust pump stroke manually, using an eclectic dial from the tractor’s cab.
文摘In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array voltage and current being used to generate the reference voltage which should be the PV panel’s operating voltage to get maximum available power. A Takagi-Sugeno (T-S) observer has been proposed and designed with non-measurable premise variables and the conditions of stability are given in terms of Linear Matrix Inequality (LMI). The simulation results show the effectiveness and robustness of the proposed method.
文摘The performance of the electronic unit pump (EUP) diesel engine is studied, it will be used in the integrated powertrain and its multi parameters are controllable. Both the theoretical analysis and experiment research are taken. A control unit for the fuel quantity and timing in crankshaft domain is designed on this basis and the engine experiment test has been done. For the constant speed camshaft driving EUP system, the fuel quantity will increase as the supply angle goes up and injection timing has no effect. The control precision can reach 1°CA. The full injection timing MAP and engine peak performance curves are made successfully.
文摘In this paper, a mathematical model of the photovoltaic （PV） pumping system＇s main components is firstly established. Then, the design of maximum power point tracking （MPPT） stage that ensures battery charging is described. This work is motivated by the need of photovoltaic generator （PVG） that efficiently extracts maximum power. The PVG is a special source of energy which has nonlinear current-voltage characteristics depending on variations in temperature and solar irradiance. In order to achieve the MPPT operating goals, a special interest is focused on the variable structure sliding mode （SM） control strategy and the classic perturb and observe （P＆O） algorithm. The permanent magnet synchronous motor （PMSM） is selected as a pump driver. The field oriented control is performed as the motor drive strategy. Simulation results show a high level of efficiency, obtained with the proposed PV based pumping system. The performance comparison between SM controller and P＆O controller has been carried out to demonstrate the effectiveness of the former in drawing more energy and a fast response against irradiation disturbances.
