Dear Editor,Plant viruses cause great economic losses to tobacco production(Dai et al.,2012).Many types of viruses have been reported to infect tobacco plants,including Tobacco mosaic virus(TMV)(Chen et al.,2014),Cucu...Dear Editor,Plant viruses cause great economic losses to tobacco production(Dai et al.,2012).Many types of viruses have been reported to infect tobacco plants,including Tobacco mosaic virus(TMV)(Chen et al.,2014),Cucumber mosaic virus(CMV)(Dai et al.,2012),Tobacco展开更多
Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,w...Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,which facilitates the non-destructive measurement of oil-film thickness,has been widely studied.However,insufficient spatial resolution around the rolling line contact zone remains a barrier despite the use of miniature piezoelectric transducers.In this study,a finite-element-aided method is utilized to simulate wave propagation through a three-layered structure of roller-oil-raceway under elastohydrodynamic lubrication(EHL)with nonlinear characteristics of the i)deformed curvature of the cylindrical roller and ii)nonuniform distribution of the fluid bulk modulus along the circumference of the oil layer being considered.A load and speed-dependent look-up table is then developed to establish an accurate relationship between the overall reflection coefficient(directly measured by an embedded ultrasonic transducer)and objective variable of the central oil-film thickness.The proposed finite-element-aided method is verified experimentally in a rollerraceway test rig with the ultrasonically measured oil-flm thickness corresponding to the values calculated using the EHLtheory.展开更多
基金supported by the 111 Project of the Education Ministry of China (No. B07049)the National High-tech R&D Program of China (No. 2012AA101504)
文摘Dear Editor,Plant viruses cause great economic losses to tobacco production(Dai et al.,2012).Many types of viruses have been reported to infect tobacco plants,including Tobacco mosaic virus(TMV)(Chen et al.,2014),Cucumber mosaic virus(CMV)(Dai et al.,2012),Tobacco
文摘Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,which facilitates the non-destructive measurement of oil-film thickness,has been widely studied.However,insufficient spatial resolution around the rolling line contact zone remains a barrier despite the use of miniature piezoelectric transducers.In this study,a finite-element-aided method is utilized to simulate wave propagation through a three-layered structure of roller-oil-raceway under elastohydrodynamic lubrication(EHL)with nonlinear characteristics of the i)deformed curvature of the cylindrical roller and ii)nonuniform distribution of the fluid bulk modulus along the circumference of the oil layer being considered.A load and speed-dependent look-up table is then developed to establish an accurate relationship between the overall reflection coefficient(directly measured by an embedded ultrasonic transducer)and objective variable of the central oil-film thickness.The proposed finite-element-aided method is verified experimentally in a rollerraceway test rig with the ultrasonically measured oil-flm thickness corresponding to the values calculated using the EHLtheory.
