Isothermal compression tests are applied to study the deformation mechanisms of TCll titanium alloy with lamellar structure under the deformation temperature range of 890-995 ℃ and strain rate range of 0.01-10 s^-1. ...Isothermal compression tests are applied to study the deformation mechanisms of TCll titanium alloy with lamellar structure under the deformation temperature range of 890-995 ℃ and strain rate range of 0.01-10 s^-1. According to the flow stress data obtained by compression tests, the deformation activations are calculated based on kinetics analysis of high temperature deformation, which are then used for deformation mechanism analysis combined with microstructure investigation. The results show that deformation mechanisms vary with deformation conditions： at low strain rate range, the deformation mechanism is mainly dislocation slip; at low temperature and high strain rate range, twinning is the main mechanism; at high temperature and high strain rate range, the deformation is mainly controlled by diffusion offl phase.展开更多
The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is ...The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is applied to study the meridional displacement of the northern edge of the EASM during the study period,and the results show an interdecadal southward shift around 1993/1994 and an indistinct northward displacement after 2007/2008.To focus on the interdecadal change around 1993/1994,composite analysis using the difference between 1979-1993 and 1994-2007 is employed.Through examination of the differences between these two periods,a significant anticyclonic anomaly is found over Mongolia,suggesting a pronounced interdecadal weakening of the Mongolian low during 1994-2007.Thus,northward advancement of the EASM may have been prevented by the anomalous northerly flow to the east of the weakened Mongolian low after 1993.Further study shows that the interdecadal weakening of the Mongolian low might be attributable to the meridional inhomogeneity of surface warming over the northern part of East Asia.Previous studies suggest that such meridional inhomogeneity would lead to a reduction in local atmospheric baroclinicity,and thus the suppression of extratropical cyclone activity over Mongolia,resulting in a southward withdrawal of the northern edge of the EASM on the interdecadal timescale.展开更多
The flow between a grooved and a flat plate was presented to investigate the effects of groove on the behavior of hydro-viscous drive. The flow was solved by using computational fluid dynamics (CFD) code, Fluent. Para...The flow between a grooved and a flat plate was presented to investigate the effects of groove on the behavior of hydro-viscous drive. The flow was solved by using computational fluid dynamics (CFD) code, Fluent. Parameters related to the flow, such as velocity, pressure, temperature, axial force and viscous torque, are obtained. The results show that pressure at the upstream notch is negative, pressure at the downstream notch is positive and pressure along the film thickness is almost the same. Dynamic pressure peak decreases as groove depth or groove number increases, but increases as output rotary speed increases. Consequently, the groove depth is suggested to be around 0.4 mm. Both the groove itself and groove parameters (i.e. groove depth, groove number) have little effect on the flow temperature. Circumferential pressure gradient induced by the groove weakens the viscous torque on the grooved plate (driven plate) greatly. It has little change as the groove depth increases. However, it decreases dramatically as the groove number increases. The experiment results show that the trend of experimental temperature and pressure are the same with numerical results. And the output rotary speed also has relationship with input flow rate and flow temperature.展开更多
This study presents the performance of a new single-stage scroll compressor used for the heat pump drying of thermally sensitive materials over a wide temperature range. The performance of the new compressor was predi...This study presents the performance of a new single-stage scroll compressor used for the heat pump drying of thermally sensitive materials over a wide temperature range. The performance of the new compressor was predicted by an ARI standard 540 map-based compressor model and verified by a semi-open drying heat pump system constructed for this purpose. A comparison of the experimental data with the predicted data proved that the new scroll compressor used in the drying heat pump works well, can supply a wide range of condensing temperatures （30--80℃） （without auxiliary heating）, and has a minimum coeffi- cient of performance （COP） above 2.0, even in the worst condition.展开更多
文摘Isothermal compression tests are applied to study the deformation mechanisms of TCll titanium alloy with lamellar structure under the deformation temperature range of 890-995 ℃ and strain rate range of 0.01-10 s^-1. According to the flow stress data obtained by compression tests, the deformation activations are calculated based on kinetics analysis of high temperature deformation, which are then used for deformation mechanism analysis combined with microstructure investigation. The results show that deformation mechanisms vary with deformation conditions： at low strain rate range, the deformation mechanism is mainly dislocation slip; at low temperature and high strain rate range, twinning is the main mechanism; at high temperature and high strain rate range, the deformation is mainly controlled by diffusion offl phase.
基金supported by National Key Basic Research and Development Projects of China[grant number 2016YFA0600601]the National Natural Science Foundation of China[grant numbers 41530503,41405045,and 41605027]
文摘The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is applied to study the meridional displacement of the northern edge of the EASM during the study period,and the results show an interdecadal southward shift around 1993/1994 and an indistinct northward displacement after 2007/2008.To focus on the interdecadal change around 1993/1994,composite analysis using the difference between 1979-1993 and 1994-2007 is employed.Through examination of the differences between these two periods,a significant anticyclonic anomaly is found over Mongolia,suggesting a pronounced interdecadal weakening of the Mongolian low during 1994-2007.Thus,northward advancement of the EASM may have been prevented by the anomalous northerly flow to the east of the weakened Mongolian low after 1993.Further study shows that the interdecadal weakening of the Mongolian low might be attributable to the meridional inhomogeneity of surface warming over the northern part of East Asia.Previous studies suggest that such meridional inhomogeneity would lead to a reduction in local atmospheric baroclinicity,and thus the suppression of extratropical cyclone activity over Mongolia,resulting in a southward withdrawal of the northern edge of the EASM on the interdecadal timescale.
基金Project(50475106)supported by the National Natural Science Foundation of China
文摘The flow between a grooved and a flat plate was presented to investigate the effects of groove on the behavior of hydro-viscous drive. The flow was solved by using computational fluid dynamics (CFD) code, Fluent. Parameters related to the flow, such as velocity, pressure, temperature, axial force and viscous torque, are obtained. The results show that pressure at the upstream notch is negative, pressure at the downstream notch is positive and pressure along the film thickness is almost the same. Dynamic pressure peak decreases as groove depth or groove number increases, but increases as output rotary speed increases. Consequently, the groove depth is suggested to be around 0.4 mm. Both the groove itself and groove parameters (i.e. groove depth, groove number) have little effect on the flow temperature. Circumferential pressure gradient induced by the groove weakens the viscous torque on the grooved plate (driven plate) greatly. It has little change as the groove depth increases. However, it decreases dramatically as the groove number increases. The experiment results show that the trend of experimental temperature and pressure are the same with numerical results. And the output rotary speed also has relationship with input flow rate and flow temperature.
基金supported by the National High Technology Research and Development Program of China(Grant No.2012AA10A510)
文摘This study presents the performance of a new single-stage scroll compressor used for the heat pump drying of thermally sensitive materials over a wide temperature range. The performance of the new compressor was predicted by an ARI standard 540 map-based compressor model and verified by a semi-open drying heat pump system constructed for this purpose. A comparison of the experimental data with the predicted data proved that the new scroll compressor used in the drying heat pump works well, can supply a wide range of condensing temperatures （30--80℃） （without auxiliary heating）, and has a minimum coeffi- cient of performance （COP） above 2.0, even in the worst condition.
