Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the po...Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the potential distribution patterns of Carex tussocks wetland is vital for their targeted conservation and restoration.The current and future(2050s and 2070s)potential habitats distribution of Carex tussocks in Northeast China were predicted using a Maximum Entropy(Maxent)model based on 68 current data of Carex tussock distributions and three groups of environmental variables(bioclimate,topography,soil properties).Results show that isothermality,seasonal precipitation variability and altitude are important factors that determine the distribution of Carex tussock.The high suitable habitat of Carex tussock is about 5.7×10^(4)km^(2) and mainly distributed in the Sanjiang Plain,Songnen Plain,Changbai Mountains and Da Hinggan Mountains.The area of stable habitats of Carex tussock is significantly higher than the lost and expanded habitats in the future climate scenarios,and the unsuitable habitats mainly occur in Da Hinggan Mountains,Xiao Hinggan Mountains and Changbai Mountains.Overall,Carex tussock wetlands at high altitude and high latitude are more sensitive to climate change,and more attention should be invested in high latitude and high altitude areas.展开更多
In this work,numerical simulation of the die filling and solidification process of AZ91D semisolid alloy was investigated to produce a thin walled connecting rod demanding a high dimensional precision.The Carreau visc...In this work,numerical simulation of the die filling and solidification process of AZ91D semisolid alloy was investigated to produce a thin walled connecting rod demanding a high dimensional precision.The Carreau viscosity model was implemented to simulate the-ow behavior of semisolid slurry during the filling.The fitted constants for the Carreau model were used to verify the simulation results.The predicted results from this model were in good agreement with the experimental results.Then the verified Carreau model was designed to predict die filling,casting defects and casting process.It was found that the predicted results had a good correlation with those in the experiment.The optimum parameters were obtained with a slurry temperature of 590 °C,a die temperature of 250 °C and an injection velocity of 2 m/s.展开更多
基金Under the auspices of the National Natural Science Foundation of China(No.41871101)the Science and Technology Development Project of Jilin Province(No.20190201115JC)the‘Strategic Priority Research Program’of the Chinese Academy of Sciences(No.XDA23060402)。
文摘Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the potential distribution patterns of Carex tussocks wetland is vital for their targeted conservation and restoration.The current and future(2050s and 2070s)potential habitats distribution of Carex tussocks in Northeast China were predicted using a Maximum Entropy(Maxent)model based on 68 current data of Carex tussock distributions and three groups of environmental variables(bioclimate,topography,soil properties).Results show that isothermality,seasonal precipitation variability and altitude are important factors that determine the distribution of Carex tussock.The high suitable habitat of Carex tussock is about 5.7×10^(4)km^(2) and mainly distributed in the Sanjiang Plain,Songnen Plain,Changbai Mountains and Da Hinggan Mountains.The area of stable habitats of Carex tussock is significantly higher than the lost and expanded habitats in the future climate scenarios,and the unsuitable habitats mainly occur in Da Hinggan Mountains,Xiao Hinggan Mountains and Changbai Mountains.Overall,Carex tussock wetlands at high altitude and high latitude are more sensitive to climate change,and more attention should be invested in high latitude and high altitude areas.
基金supported by both the National High Technical Research and Development Program of China (No. 2009AA03Z534)the Nation Basic Research Program of China (No. 2006CB605203)the International Cooperation in Technical Research and Development Program of China (No.2009DFB 50210)
文摘In this work,numerical simulation of the die filling and solidification process of AZ91D semisolid alloy was investigated to produce a thin walled connecting rod demanding a high dimensional precision.The Carreau viscosity model was implemented to simulate the-ow behavior of semisolid slurry during the filling.The fitted constants for the Carreau model were used to verify the simulation results.The predicted results from this model were in good agreement with the experimental results.Then the verified Carreau model was designed to predict die filling,casting defects and casting process.It was found that the predicted results had a good correlation with those in the experiment.The optimum parameters were obtained with a slurry temperature of 590 °C,a die temperature of 250 °C and an injection velocity of 2 m/s.
