When testing an electrohydraulic proportional valve,it is necessary to test the high frequency dynamic flow with bias.Because of the limitation of the piston stroke,a no-load hydraulic cylinder is only suitable for a ...When testing an electrohydraulic proportional valve,it is necessary to test the high frequency dynamic flow with bias.Because of the limitation of the piston stroke,a no-load hydraulic cylinder is only suitable for a reciprocating symmetrical dynamic flow test.Since the traditional differential pressure flowmeter is affected by viscosity and inertia of the fluid,it is only suitable for measuring steady flow.Therefore,a new type of double pressure differential dynamic flowmeter is designed to improve the traditional differential pressure flowmeter.The influence of fluid viscosity and inertia in the flow process are negated by subtracting the differential pressure in section expansion from the differential pressure in section contraction.The double differential pressure flowmeter is modeled and a flow meter prototype is designed.Then,the flow coefficients are identified and corrected by a practical test.Finally,the dynamic performance and steady-state precision of the flowmeter are verified by comparing with the test results of the no-load hydraulic cylinder.The double differential pressure dynamic flowmeter is proven to measure dynamic flow accurately,especially at higher dynamic frequencies.展开更多
Under the flipped classroom teaching theory, the aim of this paper is to explore whether the teaching model of“student-oriented, teacher-led” can help improve the learning effect of Japanese major students by adopti...Under the flipped classroom teaching theory, the aim of this paper is to explore whether the teaching model of“student-oriented, teacher-led” can help improve the learning effect of Japanese major students by adopting themixed online and offline teaching method of rain classroom. Two Japanese majors classes of Grade 19 in BISUwere taken as the research objects of the one-semester comparative experiment. The study found there wereobvious differences in learning effect and learning experience between the two classes. The experiment proves thatthe role of teachers in flipped classroom is more obvious than that of traditional teaching. If teachers can activelyplay the role of teacher-student interaction, Japanese professional level of the students can be effectively improved.展开更多
基金Supported by the National Natural Science Foundation of China(No.51875498)Hebei Provincial Natural Science Fund Key Project(No.E2018203339)Hebei Provincial Natural Science Foundation Steel Joint Research Fund(No.E2017203079)
文摘When testing an electrohydraulic proportional valve,it is necessary to test the high frequency dynamic flow with bias.Because of the limitation of the piston stroke,a no-load hydraulic cylinder is only suitable for a reciprocating symmetrical dynamic flow test.Since the traditional differential pressure flowmeter is affected by viscosity and inertia of the fluid,it is only suitable for measuring steady flow.Therefore,a new type of double pressure differential dynamic flowmeter is designed to improve the traditional differential pressure flowmeter.The influence of fluid viscosity and inertia in the flow process are negated by subtracting the differential pressure in section expansion from the differential pressure in section contraction.The double differential pressure flowmeter is modeled and a flow meter prototype is designed.Then,the flow coefficients are identified and corrected by a practical test.Finally,the dynamic performance and steady-state precision of the flowmeter are verified by comparing with the test results of the no-load hydraulic cylinder.The double differential pressure dynamic flowmeter is proven to measure dynamic flow accurately,especially at higher dynamic frequencies.
文摘Under the flipped classroom teaching theory, the aim of this paper is to explore whether the teaching model of“student-oriented, teacher-led” can help improve the learning effect of Japanese major students by adopting themixed online and offline teaching method of rain classroom. Two Japanese majors classes of Grade 19 in BISUwere taken as the research objects of the one-semester comparative experiment. The study found there wereobvious differences in learning effect and learning experience between the two classes. The experiment proves thatthe role of teachers in flipped classroom is more obvious than that of traditional teaching. If teachers can activelyplay the role of teacher-student interaction, Japanese professional level of the students can be effectively improved.
