We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation per...We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.展开更多
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to ...The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.展开更多
The interface evolution of TiAl/Ti6242 joint produced by transient liquid phase(TLP) bonding with Ti, Cu foils as insert metals was investigated. The results show that the surface oxide layer on TiAl plays a very impo...The interface evolution of TiAl/Ti6242 joint produced by transient liquid phase(TLP) bonding with Ti, Cu foils as insert metals was investigated. The results show that the surface oxide layer on TiAl plays a very important role in the formation process of the joint. A ‘bridge’ effect is observed because of the presence of the oxide layer on the surface of TiAl. The diffusion behavior of Cu atoms in TiAl is strongly controlled by the vacancies beneath the surface of TiAl. Based on the interface diffusion and interface wettability, a mechanism for the effect of bonding pressure, bonding temperature, holding time and stacking sequence of the insert foils on the joint formation process were proposed.展开更多
Mercury （Hg） is present in the marine environment as a natural metal often enhanced through human activities. Depending on its chemical form, Hg can cause a wide range of immunotoxic effects. In this study, the infl...Mercury （Hg） is present in the marine environment as a natural metal often enhanced through human activities. Depending on its chemical form, Hg can cause a wide range of immunotoxic effects. In this study, the influence of methyl-, ethyl- and phenylmercury as well as mercurychloride on immune functions was evaluated. Two parameters of cellular immunity, proliferation and mRNA cytokine expression of interleukin-2, -4, and transforming growth factor β, were investigated in harbor seal lymphocytes after in vitro exposure to Hg compounds. While all Hg compounds had a suppressive effect on proliferation, differences between juvenile and adult seals were found. Lymphocytes from juveniles showed a higher susceptibility to the toxic effect compared to lymphocytes from adults. Furthermore, the degree of inhibition of proliferation varied among the four Hg compounds. The organic compounds seem to be more immunotoxic than the inorganic compound. Finally, for the cytokine expression of methylmercury-incubated lymphocytes, timedependent changes were observed, but no dose-dependency was found. Marine mammals of the North Sea are burdened with Hg, and lymphocytes of harbor seals may be functionally impaired by this metal. The present in vitro study provides baseline information for future studies on the immunotoxic effects of Hg on cellular immunity of harbor seals.展开更多
TiAl has been joined employing the transient liquid phase （TLP） bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, a...TiAl has been joined employing the transient liquid phase （TLP） bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, all the joined zones are composed of five sublayers, i.e. two diffusion zones, two interfacial zones and an interlayer. It has been convinced that the formation process of the transient liquid phase controls the diffusion behavior of melting point depressant （MPD） Cu, Ni, and Fe atoms, which leads to form different interface structures of the joints.展开更多
In most engineering metallic structures,welded joints are often the locations for the crack initiation due to inherent metallurgical,geometrical defects as well as heterogeneity in mechanical properties and presence o...In most engineering metallic structures,welded joints are often the locations for the crack initiation due to inherent metallurgical,geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. In order to maintain structural integrity of welded structures for whole service life of the structure,relationship between welding process,properties(of base metal & weld joint) and performance of the structure(requirements & controlling factors of the service conditions) should be well-understood and established. The quality of the relationship between this 3P is crucial to obtain economic and safe design,fabrication and service life. Specific features of each welding and joining process should ideally be well understood by the designer for a selected material at the early stage of the design. Resulting micro-structural & mechanical and geometrical properties should be obtained to have defined or intended structural performance under either specific environment or stresses. Nowadays,use of advanced welding processes with high performance steels and aluminum alloys together with well established and high quality welding consumables ensures safe and economic design,fabrication,inspection and service of the welded components and structures. Additionally,new developments in the fitness-for-service(FFS) procedures(e. g. BS 7910,R6 and FITNET FFS) and codes have significantly increased the accuracy of the structural integrity assessment of weld flaws. More and more engineering structures are built using multi-material design approach where numbers of materials with significantly different mechanical properties are joined to create weight and cost-efficient structures. Structural safety evaluation of such material-mix structures require sound understanding and description of the welding process,interfacial & weld joint properties in conjunction with global behavior of the component under external loadings. The existing knowledge on the weld strength mismatch will significantly help to design innovative products and resolve complex deformation and fracture problems of such emerging structures. Such structures are expected to perform under severe service conditions with minimum maintenance and safely. This Houdremont Lecture will,therefore,address to the engineering significance of the relationship between different stages of the"life of the welded structure"which I have been describing as 3P(Process-Property-Performance) of welded structures.展开更多
The reconstructed temperature anomalies in the eastern China were compared with the output from a 1000-year model simulation in an attempt to evaluate the model’s regional simulation skills and to understand the caus...The reconstructed temperature anomalies in the eastern China were compared with the output from a 1000-year model simulation in an attempt to evaluate the model’s regional simulation skills and to understand the causes of climate change in China over the last millennium. The reconstructed data are the winter half-year temperature anomalies in the central region of eastern China (25°-40°N, east of 105°E) for the last 1000 years with a 30-year resolu- tion. The model used is the global atmosphere-ocean coupled climate model, ECHO-G, which was driven by time-varying external forcings including solar radiation, volcanic erup- tions, and greenhouse gas concentrations (CO2 and CH4) for the same period. The correlation coefficient between the simulated and reconstructed time series is 0.37, which is sta- tistically significant at a confidence level of 97.5%. The Me- dieval Warm Period (MWP) during 1000-1300 A.D., the Little Ice Age (LIA) during 1300-1850 A.D. and the modern warming period after 1900 A.D. are all recognizable from both the simulated and reconstructed temperatures. The anomalies associated with the LIA and the modern warming simulated by the model are in good consistency with the re- constructed counterpart. In particular during the Maunder sun-spot minimum (1670-1710 A.D.), both the simulated and reconstructed temperature anomalies reach their min- ima without any phase difference. But in the earlier MWP, significant discrepancies exist between the simulation and the reconstruction, which might reflect the degrading quality of the reconstruction data. The range of the simulated anoma- lies (1.62 K) is comparable with that of reconstructed (2.0 K). Diagnosis of the model results indicates that, during the last millennium, variations in solar radiation and volcanic activ- ity are the main controlling factors on regional temperature change, while in the recent 100 years, the change of the con- centration of greenhouse gases plays most important role in explaining the rapid temperature rising.展开更多
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.KZCX1-YW-12-01KZCX2-YW-BR-04)+1 种基金the National Natural Science Foundation of China (Nos.40876007,40806006)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.
文摘The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.
文摘The interface evolution of TiAl/Ti6242 joint produced by transient liquid phase(TLP) bonding with Ti, Cu foils as insert metals was investigated. The results show that the surface oxide layer on TiAl plays a very important role in the formation process of the joint. A ‘bridge’ effect is observed because of the presence of the oxide layer on the surface of TiAl. The diffusion behavior of Cu atoms in TiAl is strongly controlled by the vacancies beneath the surface of TiAl. Based on the interface diffusion and interface wettability, a mechanism for the effect of bonding pressure, bonding temperature, holding time and stacking sequence of the insert foils on the joint formation process were proposed.
文摘Mercury （Hg） is present in the marine environment as a natural metal often enhanced through human activities. Depending on its chemical form, Hg can cause a wide range of immunotoxic effects. In this study, the influence of methyl-, ethyl- and phenylmercury as well as mercurychloride on immune functions was evaluated. Two parameters of cellular immunity, proliferation and mRNA cytokine expression of interleukin-2, -4, and transforming growth factor β, were investigated in harbor seal lymphocytes after in vitro exposure to Hg compounds. While all Hg compounds had a suppressive effect on proliferation, differences between juvenile and adult seals were found. Lymphocytes from juveniles showed a higher susceptibility to the toxic effect compared to lymphocytes from adults. Furthermore, the degree of inhibition of proliferation varied among the four Hg compounds. The organic compounds seem to be more immunotoxic than the inorganic compound. Finally, for the cytokine expression of methylmercury-incubated lymphocytes, timedependent changes were observed, but no dose-dependency was found. Marine mammals of the North Sea are burdened with Hg, and lymphocytes of harbor seals may be functionally impaired by this metal. The present in vitro study provides baseline information for future studies on the immunotoxic effects of Hg on cellular immunity of harbor seals.
文摘TiAl has been joined employing the transient liquid phase （TLP） bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, all the joined zones are composed of five sublayers, i.e. two diffusion zones, two interfacial zones and an interlayer. It has been convinced that the formation process of the transient liquid phase controls the diffusion behavior of melting point depressant （MPD） Cu, Ni, and Fe atoms, which leads to form different interface structures of the joints.
文摘In most engineering metallic structures,welded joints are often the locations for the crack initiation due to inherent metallurgical,geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. In order to maintain structural integrity of welded structures for whole service life of the structure,relationship between welding process,properties(of base metal & weld joint) and performance of the structure(requirements & controlling factors of the service conditions) should be well-understood and established. The quality of the relationship between this 3P is crucial to obtain economic and safe design,fabrication and service life. Specific features of each welding and joining process should ideally be well understood by the designer for a selected material at the early stage of the design. Resulting micro-structural & mechanical and geometrical properties should be obtained to have defined or intended structural performance under either specific environment or stresses. Nowadays,use of advanced welding processes with high performance steels and aluminum alloys together with well established and high quality welding consumables ensures safe and economic design,fabrication,inspection and service of the welded components and structures. Additionally,new developments in the fitness-for-service(FFS) procedures(e. g. BS 7910,R6 and FITNET FFS) and codes have significantly increased the accuracy of the structural integrity assessment of weld flaws. More and more engineering structures are built using multi-material design approach where numbers of materials with significantly different mechanical properties are joined to create weight and cost-efficient structures. Structural safety evaluation of such material-mix structures require sound understanding and description of the welding process,interfacial & weld joint properties in conjunction with global behavior of the component under external loadings. The existing knowledge on the weld strength mismatch will significantly help to design innovative products and resolve complex deformation and fracture problems of such emerging structures. Such structures are expected to perform under severe service conditions with minimum maintenance and safely. This Houdremont Lecture will,therefore,address to the engineering significance of the relationship between different stages of the"life of the welded structure"which I have been describing as 3P(Process-Property-Performance) of welded structures.
基金supported by the Innovation Key Project of Chinese Academy of Sciences(Grant No.KZCX3-SW-321)the National Natural Science Foundation of China(Grant Nos.40272123,40475035,40331013)the lnnovation Project of Nanjing Institute of Geography and Limnology(Grant No.CXNIGLAS-A02-06).
文摘The reconstructed temperature anomalies in the eastern China were compared with the output from a 1000-year model simulation in an attempt to evaluate the model’s regional simulation skills and to understand the causes of climate change in China over the last millennium. The reconstructed data are the winter half-year temperature anomalies in the central region of eastern China (25°-40°N, east of 105°E) for the last 1000 years with a 30-year resolu- tion. The model used is the global atmosphere-ocean coupled climate model, ECHO-G, which was driven by time-varying external forcings including solar radiation, volcanic erup- tions, and greenhouse gas concentrations (CO2 and CH4) for the same period. The correlation coefficient between the simulated and reconstructed time series is 0.37, which is sta- tistically significant at a confidence level of 97.5%. The Me- dieval Warm Period (MWP) during 1000-1300 A.D., the Little Ice Age (LIA) during 1300-1850 A.D. and the modern warming period after 1900 A.D. are all recognizable from both the simulated and reconstructed temperatures. The anomalies associated with the LIA and the modern warming simulated by the model are in good consistency with the re- constructed counterpart. In particular during the Maunder sun-spot minimum (1670-1710 A.D.), both the simulated and reconstructed temperature anomalies reach their min- ima without any phase difference. But in the earlier MWP, significant discrepancies exist between the simulation and the reconstruction, which might reflect the degrading quality of the reconstruction data. The range of the simulated anoma- lies (1.62 K) is comparable with that of reconstructed (2.0 K). Diagnosis of the model results indicates that, during the last millennium, variations in solar radiation and volcanic activ- ity are the main controlling factors on regional temperature change, while in the recent 100 years, the change of the con- centration of greenhouse gases plays most important role in explaining the rapid temperature rising.
