The high-speed train transmission system,experiencing both the internal excitation originating from gear meshing and the external excitation originating from the wheel-rail interaction,exhibits complex dynamic behavio...The high-speed train transmission system,experiencing both the internal excitation originating from gear meshing and the external excitation originating from the wheel-rail interaction,exhibits complex dynamic behavior in the actual service environment.This paper focuses on the gearbox in the high-speed train to carry out the bench test,in which various operat-ing conditions(torques and rotation speeds)were set up and the excitation condition covering both internal and external was created.Acceleration responses on multiple positions of the gearbox were acquired in the test and the vibration behavior of the gearbox was studied.Meanwhile,a stochastic excitation modal test was also carried out on the test bench under different torques,and the modal parameter of the gearbox was identified.Finally,the sweep frequency response of the gearbox under gear meshing excitation was analyzed through dynamic modeling.The results showed that the torque has an attenuating effect on the amplitude of gear meshing frequency on the gearbox,and the effect of external excitation on the gearbox vibration cannot be ignored,especially under the rated operating condition.It was also found that the torque affects the modal param-eter of the gearbox significantly.The torque has a great effect on both the gear meshing stiffness and the bearing stiffness in the transmission system,which is the inherent reason for the changed modal characteristics observed in the modal test and affects the vibration behavior of the gearbox consequently.展开更多
Background:Due to the wide variety of morphology,size,and dynamics,selecting an optimal valve size and location poses great difficulty in percutaneous pulmonary valve implantation(PPVI).This study aimed to report our ...Background:Due to the wide variety of morphology,size,and dynamics,selecting an optimal valve size and location poses great difficulty in percutaneous pulmonary valve implantation(PPVI).This study aimed to report our experience with in vitro bench testing using patient-specific three-dimensional(3D)-printed models for planning PPVI with the Venus P-valve.Methods:Patient-specific 3D soft models were generated using PolyJet printing with a compliant synthetic material in 15 patients scheduled to undergo PPVI between July 2018 and July 2020 in Central China Fuwai Hospital of Zhengzhou University.Results:3D model bench testing altered treatment strategy in all patients(100%).One patient was referred for surgery because testing revealed that even the largest Venus P-valve would not anchor properly.In the remaining 14 patients,valve size and/or implantation location was altered to avoid valve migration and/or compression coronary artery.In four patients,it was decided to change the point anchoring because of inverted cone-shaped right ventricular outflow tract(RVOT)(n=2)or risk of compression coronary artery(n=2).Concerning sizing,we found that an oversize of 2-5 mm suffices.Anchoring of the valve was dictated by the flaring of the in-and outflow portion in the pulmonary artery.PPVI was successful in all 14 patients(absence of valve migration,no coronary compression,and none-to-mild residual pulmonary regurgitation[PR]).The diameter of the Venus P-valve in the 3D simulation group was significantly smaller than that of the conventional planning group(36[2]vs.32[4],Z=-3.77,P<0.001).Conclusions:In vitro testing indicated no need to oversize the Venus P-valve to the degree recommended by the balloon-sizing technique,as 2-5 mm sufficed.展开更多
Framework and basic parameters of a test bench for motor drive system of electric vehicle (EV) are illuminated. Two kinds of electric drive models, one was for the electric vehicle drived on real road, the other was f...Framework and basic parameters of a test bench for motor drive system of electric vehicle (EV) are illuminated. Two kinds of electric drive models, one was for the electric vehicle drived on real road, the other was for that on test bench, are put forward. Then, dynamic analysis of these models is made in detail. Inertia matching method of the test bench is researched and some useful formulas and graphs are brought forward. The experiment of an electric bus is introduced in order to explain the usage of this inertia matching method.展开更多
A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection co...A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection control method is given out and the control accuracy can be 0.1° crank degree. The bench can test both mechanical unit pump and electronic unit pump. A test model-PLD12 electronic unit pump is tested. Full pump delivery map and some influence factors test is done. Experimental results show that the injection quantity is linear with the delivery angle. The quantity change rate is 15% when fuel temperature increases 30 ℃. The delivery quantity per cycle increases 30 mg at 28 V drive voltage. The average delivery difference for two same type pumps is 5 %. Test results show that the bench can be used for unit pump verification.展开更多
The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental ...The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental verification are studied.First,considering the stick-slip phenomenon in the clutch engagement process,a detailed 9-degrees-of-freedom(DOF)model including the body,each cylinder of the engine,clutch and friction lining,torsional damper,transmission and other driveline parts is established,and the calculation formula of friction torque in the clutch engagement process is determined.Second,the influence of the friction gradient characteristics on the amplification or attenuation of the automobile friction judder is analyzed,and the corresponding stability analysis and the numerical simulation of different friction gradient values are carried out with MATLAB/Simulink software.Finally,judder bench test equipment and a corresponding damping test program are developed,and the relationship between the friction coefficient gradient characteristics and the system damping is analyzed.After a large number of tests,the evaluation basis of the test is determined.The research results show that the friction lining with negative gradient characteristics of the friction coefficient will have a judder signal.When the friction gradient value is less than-0.005 s/m,the judder signal of the measured clutch cannot be completely attenuated,and the judder phenomenon occurs.When the friction gradient is greater than-0.005 s/m,the judder signal can be significantly suppressed and the system connection tends to be stable.展开更多
The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)project will use 6001.3 GHz fundamental power couplers,which are modified based on TTF-Ⅲ power couplers,for continuous-wave operation with input...The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)project will use 6001.3 GHz fundamental power couplers,which are modified based on TTF-Ⅲ power couplers,for continuous-wave operation with input power up to approximately 7 kW.The first batch of 20 sets of 1.3 GHz coupler prototypes was fabricated from three domestic manufacturers for the SHINE project.To better characterize the radio frequency conditioning phenomena for validating the performance of power couplers,a room temperature test stand was designed,constructed,and commissioned for the SHINE 1.3 GHz power couplers.In addition,a horizontal test cryostat was built to test the 1.3 GHz superconducting cavities,fundamental power couplers,tuners,and other components as a set.The results of these tests indicate that the 1.3 GHz couplers are capable of handling up to 14 kW continuous waves.Herein,the main aspects of the radio frequency design and construction of the test stand,along with the test results of the high-power conditioning of the 1.3 GHz couplers,are described.展开更多
The spherical plain bearing test bench is a necessary detecting equipment in the research process of self?lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of t...The spherical plain bearing test bench is a necessary detecting equipment in the research process of self?lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of the wear?depth detecting system of bearing test benches and then a ect the accuracy of the wear?depth detecting data. However, few researches about the spherical plain bearing test benches can be found with the implementation of the detect?ing error compensation. Based on the self?made modular spherical plain bearing test bench, two main causes of ther?mal errors, the friction heat of bearings and the environmental temperature variation, are analysed. The thermal errors caused by the friction heat of bearings are calculated, and the thermal deformation of the wear?depth detecting sys?tem caused by the varying environmental temperatures is detected. In view of the above results, the environmental temperature variation is the main cause of the two error factors. When the environmental temperatures rise is 10.3 °C, the thermal deformation is approximately 0.01 mm. In addition, the comprehensive compensating model of the thermal error of the wear?depth detecting system is built by multiple linear regression(MLR) and time series analysis. Compared with the detecting data of the thermal errors, the comprehensive compensating model has higher fitting precision, and the maximum residual is only 1 μm. A comprehensive compensating model of the thermal error of the wear?depth detecting system is proposed, which provides a theoretical basis for the improvement of the real?time wear?depth detecting precision of the spherical plain bearing test bench.展开更多
The bench top test is one of the most important and effective methods to evaluate the total thermal protective performance(TPP) of firefighters' protective clothing,which is greatly influenced by the air gaps entr...The bench top test is one of the most important and effective methods to evaluate the total thermal protective performance(TPP) of firefighters' protective clothing,which is greatly influenced by the air gaps entrapped.In this paper,to investigate the effect of air gap width on TPP,a new improved apparatus with two height changeable buttons to hold the thermal sensor was developed to get a series of air gap sizes from 0 mm to 40 mm.The TPP of two types of flame-resistant outer fabrics was measured with TPP test apparatus respectively.Analysis of temperature rise with each air gap width was made to determine the effects of different air gaps on protective performance.It was indicated that air gap size had great effect on TPP of fabrics in the bench top test.An air gap width above 8 mm was suggested for the thermal protective clothing design.展开更多
A thimble zirconia oxygen sensor electrolyte and their interface were observed with was prepared with YSZ. The surfaces of the Pt electrode, a scanning electron microscope (SEM).The sensor was examined with engine b...A thimble zirconia oxygen sensor electrolyte and their interface were observed with was prepared with YSZ. The surfaces of the Pt electrode, a scanning electron microscope (SEM).The sensor was examined with engine bench test to evaluate the essential performance. The basic function such as electromotive force output and response time was discussed. The oscillograph trace was also obtained and analyzed with four different frequencies. The experimental results reveal that the oxygen sensor has high performances meeting the demands of practical applications..展开更多
This paper presents a simulation and modeling package based on Matlab for a parallel hybrid electric motorcycle (HEM). The package consists of several main detailed models: internal combustion engine (ICE), motor, con...This paper presents a simulation and modeling package based on Matlab for a parallel hybrid electric motorcycle (HEM). The package consists of several main detailed models: internal combustion engine (ICE), motor, continuously variable transmission (CVT), battery, energy management system (EMS) etc . Each component is built as a library, and can be connected together according to the parallel HEM's topology. Simulation results, such as ICE power demand, motor power demand, battery instantaneous state of charge (SOC), pollution emissions etc. are given and discussed. Lastly experimental data verify our simulation results.展开更多
As one of the important ways to utilize hydrogen energy,fuel cells are receiving more and more attention and research from countries and institutions.To meet the practical needs of testing the performance of high-powe...As one of the important ways to utilize hydrogen energy,fuel cells are receiving more and more attention and research from countries and institutions.To meet the practical needs of testing the performance of high-power fuel-cell systems and simulate the actual application environment as much as possible,a fuel-cell system test bench is usually used to test the system performance,in which the cooling-temperature control of the test bench has a great impact on the results of the performance of the fuel-cell system.This paper studies the cooling-temperature control strategy of a 150-kW-class fuel-cell engine test platform,proposes a new test-bench cooling-system structure with a thermostat and heat exchanger as the main heat-dissipation components,and compares and analyzes the impact of coordinated thermostat and heat-exchanger control on the fuel-cell system test performance.The test results show that the control strategy of the coordinated operation of a thermostat and heat exchanger can maintain the steady-state error to within±0.3℃and maintain the temperature variation to within±1.5℃during the loading-condition test,so as to avoid the limitation of system output performance due to excessive cooling-temperature fluctuation and ensure that the fuel-cell engine performance-test process is carried out smoothly and efficiently.展开更多
As a study basis in the field of design and research of harvester prototype,bench cutting test is to provide best parameters for the cutter design.In order to obtain the optimal parameters of cutter of the hemp harves...As a study basis in the field of design and research of harvester prototype,bench cutting test is to provide best parameters for the cutter design.In order to obtain the optimal parameters of cutter of the hemp harvester,cutting tests on hemp stalk were conducted to examine the influences of different geometrical parameters(length and edge type)of blade,different cutting speeds and stalk feeding speeds of reciprocating single movable blade and reciprocating double movable blades on the cutting performances(cutting power,cutting quality and synthesis score)by using self-designed test bench.According to features of different test factors,multi-factors orthogonal test was applied to determine the best combination of blade length,blade edge type and number of movable blade.Then with these parameters fixed,the optimal parameters for the factors of cutting speed and stalk feeding speed were obtained by quadratic-regression rotatable orthogonal test.According to the test results,the best combination of hemp stalk cutting was that using cutter with reciprocating double movable blades of long(120 mm)and serrated-edge at cutting speed of 1.1704 m/s and stalk feeding speed of 0.7079 m/s.The tests and analysis results can be applied into subsequent related researches on hemp harvesters.展开更多
Electrolysers,which convert electricity into hydrogen,have the potential to offer a variety of electrical-grid services,therefore facilitating the integration of intermittent renewables into electrical grids.Among var...Electrolysers,which convert electricity into hydrogen,have the potential to offer a variety of electrical-grid services,therefore facilitating the integration of intermittent renewables into electrical grids.Among various activities that aim to unlock this hidden value,the 3-year European Union project QualyGridS launched in 2017 aims to establish standardized testing protocols for electrolysers to perform electricity-grid services.This paper shares experience and intermediate results of QualyGridS with respect to the testing protocols,test benches and testing results.The results of this work facilitate mutual understanding between the electricity industry and the hydrogen industry,support further development of the cross-sector testing standards,guide the design and selection of grid-service-oriented electrolyser applications and foster the transition towards a fossil-free-energy future based on high shares of hydrogen and other renewable solutions.展开更多
To meet the requirement of“zero speed”for precision sowing,the instantaneous speed of seed falling into the seed bed should be equal to the opposite direction of the forward speed of the machine.Through analyzing th...To meet the requirement of“zero speed”for precision sowing,the instantaneous speed of seed falling into the seed bed should be equal to the opposite direction of the forward speed of the machine.Through analyzing the principle of seed guiding process,the main influencing factors affecting the contour curve of the seed tube were determined to plan the seed guiding path and realize zero speed seed delivery.With the help of EDEM simulation software,taking the inclination angle of seed tube end,operating speed of the metering disc,and machine’s forward speed as the experimental factors,a single-factor simulation test was conducted with the pass rate,replay rate,and missing seeding rate as experimental indexes.The results of the simulation test showed that the range of inclination angle of the seed tube end was 23°-40°,the range of machine forward speed was 5-9 km/h,and the range of operating speed of the metering disc was 15-40 r/min.The quadratic orthogonal rotation combination test method was carried out using the bench test,and a mathematical regression model was established between experimental factors and experimental indexes to determine the priority order of factors,and the best combination of factors.The test results showed that the pass rate was 93.25%,the replay rate was 2.97%and the missing seeding rate was 3.78%under the condition with the inclination angle of seed tube end of 32.28°,the forward speed of the machine of 6.89 km/h and the operating speed of the metering disc of 28.67 r/min,which can meet the requirements of relevant national standards.展开更多
The small size, light weight, irregular shape, and impurities that characterize seed groups increase clogging tendencies in the traditional seed-metering device thereby making it difficult to achieve high-speed precis...The small size, light weight, irregular shape, and impurities that characterize seed groups increase clogging tendencies in the traditional seed-metering device thereby making it difficult to achieve high-speed precision seeding. A pneumatic seed-metering device with good seed-filling performance for carrot was designed in this study. By analyzing the movement state of seeds in the device under the theoretical condition, it was concluded that the minimum critical negative pressure value of air chamber was 0.32 kPa, which provided a theoretical basis for simulation and testing. ANSYS 17.0 Software was used to simulate the shape of the seeding plate hole. By comparing the pressure, air flow stability between the suction surface and the plug removal surface of the convection field, it was concluded that the conical hole was optimal. A bench verification test was conducted on the device. The average qualified rate, missing rate, and replaying rate were 81.48%, 4.07%, and 14.45%, respectively, which provided a strong reference for the design of carrot precision seed-metering device.展开更多
Both seeding performance of seed metering unit and travel speed of seed planter have significant effects on seeding quality,thereby affecting crop growth and yields.In order to determine the effects of different trave...Both seeding performance of seed metering unit and travel speed of seed planter have significant effects on seeding quality,thereby affecting crop growth and yields.In order to determine the effects of different travel speeds on seed spacing uniformity,four different types of seed meters were evaluated at five different travel speeds on seed meter test bench and in field.The tested seed meters included a finger pickup seed meter,a scoop-wheel seed meter,an air-pressure type seed meter and an air-blowing type seed meter.The seeding performance of the horizontal distribution of seeds within a row was described by using the coefficient of variation,the quality of feed index,the multiple index and the miss-seeding index.Experiments were performed in laboratory and field,respectively.Results indicated that different travel speeds have statistically significant effects on seed spacing uniformity.The four types of seed meters performed better on the seed meter test bench than in the field.Coefficient of variation increases and quality of feed index decreases as the travel speed of seed planter increases.The best seed spacing uniformity was obtained with the air-pressure type seed meter,followed with the air-blowing type seed meter,the finger pickup seed meter and the scoop-wheel seed meter.There were considerable differences between the performances of the scoop-wheel seed meter in the bench test and field test;the seeding qualities were much better in the bench test than in the field test.The scoop-wheel seed meter is more sensitive to vibration than the other types of seed meters.展开更多
基金The authors are grateful for the financial support from the National Key Research and Development Program of China(Grant No.2021YFB3400701)the Fundamental Research Funds for the Central Universities(Science and technology leading talent team project,Grant No.2022JBQY007).
文摘The high-speed train transmission system,experiencing both the internal excitation originating from gear meshing and the external excitation originating from the wheel-rail interaction,exhibits complex dynamic behavior in the actual service environment.This paper focuses on the gearbox in the high-speed train to carry out the bench test,in which various operat-ing conditions(torques and rotation speeds)were set up and the excitation condition covering both internal and external was created.Acceleration responses on multiple positions of the gearbox were acquired in the test and the vibration behavior of the gearbox was studied.Meanwhile,a stochastic excitation modal test was also carried out on the test bench under different torques,and the modal parameter of the gearbox was identified.Finally,the sweep frequency response of the gearbox under gear meshing excitation was analyzed through dynamic modeling.The results showed that the torque has an attenuating effect on the amplitude of gear meshing frequency on the gearbox,and the effect of external excitation on the gearbox vibration cannot be ignored,especially under the rated operating condition.It was also found that the torque affects the modal param-eter of the gearbox significantly.The torque has a great effect on both the gear meshing stiffness and the bearing stiffness in the transmission system,which is the inherent reason for the changed modal characteristics observed in the modal test and affects the vibration behavior of the gearbox consequently.
基金Henan Province health science and technology innovation talents training project(No.YXKC 2020047)
文摘Background:Due to the wide variety of morphology,size,and dynamics,selecting an optimal valve size and location poses great difficulty in percutaneous pulmonary valve implantation(PPVI).This study aimed to report our experience with in vitro bench testing using patient-specific three-dimensional(3D)-printed models for planning PPVI with the Venus P-valve.Methods:Patient-specific 3D soft models were generated using PolyJet printing with a compliant synthetic material in 15 patients scheduled to undergo PPVI between July 2018 and July 2020 in Central China Fuwai Hospital of Zhengzhou University.Results:3D model bench testing altered treatment strategy in all patients(100%).One patient was referred for surgery because testing revealed that even the largest Venus P-valve would not anchor properly.In the remaining 14 patients,valve size and/or implantation location was altered to avoid valve migration and/or compression coronary artery.In four patients,it was decided to change the point anchoring because of inverted cone-shaped right ventricular outflow tract(RVOT)(n=2)or risk of compression coronary artery(n=2).Concerning sizing,we found that an oversize of 2-5 mm suffices.Anchoring of the valve was dictated by the flaring of the in-and outflow portion in the pulmonary artery.PPVI was successful in all 14 patients(absence of valve migration,no coronary compression,and none-to-mild residual pulmonary regurgitation[PR]).The diameter of the Venus P-valve in the 3D simulation group was significantly smaller than that of the conventional planning group(36[2]vs.32[4],Z=-3.77,P<0.001).Conclusions:In vitro testing indicated no need to oversize the Venus P-valve to the degree recommended by the balloon-sizing technique,as 2-5 mm sufficed.
文摘Framework and basic parameters of a test bench for motor drive system of electric vehicle (EV) are illuminated. Two kinds of electric drive models, one was for the electric vehicle drived on real road, the other was for that on test bench, are put forward. Then, dynamic analysis of these models is made in detail. Inertia matching method of the test bench is researched and some useful formulas and graphs are brought forward. The experiment of an electric bus is introduced in order to explain the usage of this inertia matching method.
基金the Ministerial Level Advanced Research Foundation (404050301 .4)
文摘A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection control method is given out and the control accuracy can be 0.1° crank degree. The bench can test both mechanical unit pump and electronic unit pump. A test model-PLD12 electronic unit pump is tested. Full pump delivery map and some influence factors test is done. Experimental results show that the injection quantity is linear with the delivery angle. The quantity change rate is 15% when fuel temperature increases 30 ℃. The delivery quantity per cycle increases 30 mg at 28 V drive voltage. The average delivery difference for two same type pumps is 5 %. Test results show that the bench can be used for unit pump verification.
基金Supported by National Natural Science Foundation of China (Grant No.51775249)。
文摘The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental verification are studied.First,considering the stick-slip phenomenon in the clutch engagement process,a detailed 9-degrees-of-freedom(DOF)model including the body,each cylinder of the engine,clutch and friction lining,torsional damper,transmission and other driveline parts is established,and the calculation formula of friction torque in the clutch engagement process is determined.Second,the influence of the friction gradient characteristics on the amplification or attenuation of the automobile friction judder is analyzed,and the corresponding stability analysis and the numerical simulation of different friction gradient values are carried out with MATLAB/Simulink software.Finally,judder bench test equipment and a corresponding damping test program are developed,and the relationship between the friction coefficient gradient characteristics and the system damping is analyzed.After a large number of tests,the evaluation basis of the test is determined.The research results show that the friction lining with negative gradient characteristics of the friction coefficient will have a judder signal.When the friction gradient value is less than-0.005 s/m,the judder signal of the measured clutch cannot be completely attenuated,and the judder phenomenon occurs.When the friction gradient is greater than-0.005 s/m,the judder signal can be significantly suppressed and the system connection tends to be stable.
基金supported by Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)。
文摘The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)project will use 6001.3 GHz fundamental power couplers,which are modified based on TTF-Ⅲ power couplers,for continuous-wave operation with input power up to approximately 7 kW.The first batch of 20 sets of 1.3 GHz coupler prototypes was fabricated from three domestic manufacturers for the SHINE project.To better characterize the radio frequency conditioning phenomena for validating the performance of power couplers,a room temperature test stand was designed,constructed,and commissioned for the SHINE 1.3 GHz power couplers.In addition,a horizontal test cryostat was built to test the 1.3 GHz superconducting cavities,fundamental power couplers,tuners,and other components as a set.The results of these tests indicate that the 1.3 GHz couplers are capable of handling up to 14 kW continuous waves.Herein,the main aspects of the radio frequency design and construction of the test stand,along with the test results of the high-power conditioning of the 1.3 GHz couplers,are described.
基金Supported by National Natural Science Foundation of China(Grant No.51405422)Hebei Provincial Natural Science Foundation of China(Grant No.E2015203113)Technological Innovation Fund of Aviation Industry of China(Grant No.2014E00468R)
文摘The spherical plain bearing test bench is a necessary detecting equipment in the research process of self?lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of the wear?depth detecting system of bearing test benches and then a ect the accuracy of the wear?depth detecting data. However, few researches about the spherical plain bearing test benches can be found with the implementation of the detect?ing error compensation. Based on the self?made modular spherical plain bearing test bench, two main causes of ther?mal errors, the friction heat of bearings and the environmental temperature variation, are analysed. The thermal errors caused by the friction heat of bearings are calculated, and the thermal deformation of the wear?depth detecting sys?tem caused by the varying environmental temperatures is detected. In view of the above results, the environmental temperature variation is the main cause of the two error factors. When the environmental temperatures rise is 10.3 °C, the thermal deformation is approximately 0.01 mm. In addition, the comprehensive compensating model of the thermal error of the wear?depth detecting system is built by multiple linear regression(MLR) and time series analysis. Compared with the detecting data of the thermal errors, the comprehensive compensating model has higher fitting precision, and the maximum residual is only 1 μm. A comprehensive compensating model of the thermal error of the wear?depth detecting system is proposed, which provides a theoretical basis for the improvement of the real?time wear?depth detecting precision of the spherical plain bearing test bench.
基金National Natural Science Foundation of China (No. 50876019)the Research Fund for the Doctoral Program of Higher Education of China (No. 200802550009)Fundamental Research Funds for the Central Universities,China
文摘The bench top test is one of the most important and effective methods to evaluate the total thermal protective performance(TPP) of firefighters' protective clothing,which is greatly influenced by the air gaps entrapped.In this paper,to investigate the effect of air gap width on TPP,a new improved apparatus with two height changeable buttons to hold the thermal sensor was developed to get a series of air gap sizes from 0 mm to 40 mm.The TPP of two types of flame-resistant outer fabrics was measured with TPP test apparatus respectively.Analysis of temperature rise with each air gap width was made to determine the effects of different air gaps on protective performance.It was indicated that air gap size had great effect on TPP of fabrics in the bench top test.An air gap width above 8 mm was suggested for the thermal protective clothing design.
文摘A thimble zirconia oxygen sensor electrolyte and their interface were observed with was prepared with YSZ. The surfaces of the Pt electrode, a scanning electron microscope (SEM).The sensor was examined with engine bench test to evaluate the essential performance. The basic function such as electromotive force output and response time was discussed. The oscillograph trace was also obtained and analyzed with four different frequencies. The experimental results reveal that the oxygen sensor has high performances meeting the demands of practical applications..
文摘This paper presents a simulation and modeling package based on Matlab for a parallel hybrid electric motorcycle (HEM). The package consists of several main detailed models: internal combustion engine (ICE), motor, continuously variable transmission (CVT), battery, energy management system (EMS) etc . Each component is built as a library, and can be connected together according to the parallel HEM's topology. Simulation results, such as ICE power demand, motor power demand, battery instantaneous state of charge (SOC), pollution emissions etc. are given and discussed. Lastly experimental data verify our simulation results.
文摘As one of the important ways to utilize hydrogen energy,fuel cells are receiving more and more attention and research from countries and institutions.To meet the practical needs of testing the performance of high-power fuel-cell systems and simulate the actual application environment as much as possible,a fuel-cell system test bench is usually used to test the system performance,in which the cooling-temperature control of the test bench has a great impact on the results of the performance of the fuel-cell system.This paper studies the cooling-temperature control strategy of a 150-kW-class fuel-cell engine test platform,proposes a new test-bench cooling-system structure with a thermostat and heat exchanger as the main heat-dissipation components,and compares and analyzes the impact of coordinated thermostat and heat-exchanger control on the fuel-cell system test performance.The test results show that the control strategy of the coordinated operation of a thermostat and heat exchanger can maintain the steady-state error to within±0.3℃and maintain the temperature variation to within±1.5℃during the loading-condition test,so as to avoid the limitation of system output performance due to excessive cooling-temperature fluctuation and ensure that the fuel-cell engine performance-test process is carried out smoothly and efficiently.
基金We greatly appreciate the careful and precise reviews by the anonymous reviewers and editors.This researchwas financially supported by the National Key R&D Program of China(2016YFD0701405-02)China Agriculture Research System for Bast and Leaf Fiber Crops(CARS-19-E22)the Agricultural Science and Technology Innovation Program of Chinese Academy of AgriculturalSciences(ASTIP,CAAS).
文摘As a study basis in the field of design and research of harvester prototype,bench cutting test is to provide best parameters for the cutter design.In order to obtain the optimal parameters of cutter of the hemp harvester,cutting tests on hemp stalk were conducted to examine the influences of different geometrical parameters(length and edge type)of blade,different cutting speeds and stalk feeding speeds of reciprocating single movable blade and reciprocating double movable blades on the cutting performances(cutting power,cutting quality and synthesis score)by using self-designed test bench.According to features of different test factors,multi-factors orthogonal test was applied to determine the best combination of blade length,blade edge type and number of movable blade.Then with these parameters fixed,the optimal parameters for the factors of cutting speed and stalk feeding speed were obtained by quadratic-regression rotatable orthogonal test.According to the test results,the best combination of hemp stalk cutting was that using cutter with reciprocating double movable blades of long(120 mm)and serrated-edge at cutting speed of 1.1704 m/s and stalk feeding speed of 0.7079 m/s.The tests and analysis results can be applied into subsequent related researches on hemp harvesters.
基金This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No.735485This joint undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and Hydrogen Europe and N.ERGHY.
文摘Electrolysers,which convert electricity into hydrogen,have the potential to offer a variety of electrical-grid services,therefore facilitating the integration of intermittent renewables into electrical grids.Among various activities that aim to unlock this hidden value,the 3-year European Union project QualyGridS launched in 2017 aims to establish standardized testing protocols for electrolysers to perform electricity-grid services.This paper shares experience and intermediate results of QualyGridS with respect to the testing protocols,test benches and testing results.The results of this work facilitate mutual understanding between the electricity industry and the hydrogen industry,support further development of the cross-sector testing standards,guide the design and selection of grid-service-oriented electrolyser applications and foster the transition towards a fossil-free-energy future based on high shares of hydrogen and other renewable solutions.
基金sponsored by the Natural Science Foundation of Shandong Province(Grant No.ZR202111230084)Qingdao Science and Technology Demonstration and Guidance Project(Grant No.2237xdny17nsh)+2 种基金Shandong Science and Technology SMEs Innovation Capacity Improvement Project(Grant No.2021TSGC 1428)Key R&D Plan of Shandong Province(Grant No.2019GNC106056)Key R&D Plan of Shandong Province(Grant No.2017NC212006)and Qingdao Minsheng Science and Technology Plan(Grant No.173352nsh).
文摘To meet the requirement of“zero speed”for precision sowing,the instantaneous speed of seed falling into the seed bed should be equal to the opposite direction of the forward speed of the machine.Through analyzing the principle of seed guiding process,the main influencing factors affecting the contour curve of the seed tube were determined to plan the seed guiding path and realize zero speed seed delivery.With the help of EDEM simulation software,taking the inclination angle of seed tube end,operating speed of the metering disc,and machine’s forward speed as the experimental factors,a single-factor simulation test was conducted with the pass rate,replay rate,and missing seeding rate as experimental indexes.The results of the simulation test showed that the range of inclination angle of the seed tube end was 23°-40°,the range of machine forward speed was 5-9 km/h,and the range of operating speed of the metering disc was 15-40 r/min.The quadratic orthogonal rotation combination test method was carried out using the bench test,and a mathematical regression model was established between experimental factors and experimental indexes to determine the priority order of factors,and the best combination of factors.The test results showed that the pass rate was 93.25%,the replay rate was 2.97%and the missing seeding rate was 3.78%under the condition with the inclination angle of seed tube end of 32.28°,the forward speed of the machine of 6.89 km/h and the operating speed of the metering disc of 28.67 r/min,which can meet the requirements of relevant national standards.
基金supported by the National Key R&D Program of China“Vegetable Intelligent Fine Production Technology and Equipment R&D” (Grant No.2017YFD0701302).
文摘The small size, light weight, irregular shape, and impurities that characterize seed groups increase clogging tendencies in the traditional seed-metering device thereby making it difficult to achieve high-speed precision seeding. A pneumatic seed-metering device with good seed-filling performance for carrot was designed in this study. By analyzing the movement state of seeds in the device under the theoretical condition, it was concluded that the minimum critical negative pressure value of air chamber was 0.32 kPa, which provided a theoretical basis for simulation and testing. ANSYS 17.0 Software was used to simulate the shape of the seeding plate hole. By comparing the pressure, air flow stability between the suction surface and the plug removal surface of the convection field, it was concluded that the conical hole was optimal. A bench verification test was conducted on the device. The average qualified rate, missing rate, and replaying rate were 81.48%, 4.07%, and 14.45%, respectively, which provided a strong reference for the design of carrot precision seed-metering device.
基金supported by the National Natural Science Foundation of China(Grant No.51575515)the National Science and Technology Research Program(2013BAD08B01-3)the National Industry System of Corn Technology of P.R.China(CARS-02).
文摘Both seeding performance of seed metering unit and travel speed of seed planter have significant effects on seeding quality,thereby affecting crop growth and yields.In order to determine the effects of different travel speeds on seed spacing uniformity,four different types of seed meters were evaluated at five different travel speeds on seed meter test bench and in field.The tested seed meters included a finger pickup seed meter,a scoop-wheel seed meter,an air-pressure type seed meter and an air-blowing type seed meter.The seeding performance of the horizontal distribution of seeds within a row was described by using the coefficient of variation,the quality of feed index,the multiple index and the miss-seeding index.Experiments were performed in laboratory and field,respectively.Results indicated that different travel speeds have statistically significant effects on seed spacing uniformity.The four types of seed meters performed better on the seed meter test bench than in the field.Coefficient of variation increases and quality of feed index decreases as the travel speed of seed planter increases.The best seed spacing uniformity was obtained with the air-pressure type seed meter,followed with the air-blowing type seed meter,the finger pickup seed meter and the scoop-wheel seed meter.There were considerable differences between the performances of the scoop-wheel seed meter in the bench test and field test;the seeding qualities were much better in the bench test than in the field test.The scoop-wheel seed meter is more sensitive to vibration than the other types of seed meters.