A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelaye...A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelayer with an average hardness of~HV 1170 is formed.The hardness was increased by WC and TiN reinforcingparticles,dissolved Co atoms in Ti,and the formation of ultrafine grains.WC particles were incorporated into the Tisubstrate owing to the intense frictional interaction/heating at the tool-plate interface(~1000℃),which led to strengthloss and wear of the tool.The Williamson-Hall analysis of the XRD peaks of the SFSed sample confirmed a significantlysmall crystallite size(~100 nm).Wear tests showed that the wear resistance of the composite structure was about 4.5times higher than that of the CP-Ti.Friction analysis revealed a significant reduction in average value and fluctuations ofthe friction coefficient.展开更多
This paper assesses the various factors contributing to climate change in the region of the Kashaffoud G-WADI Basin in Iron;quanti-fies the local impacts of climate change,especially local water scarcity;and simulates...This paper assesses the various factors contributing to climate change in the region of the Kashaffoud G-WADI Basin in Iron;quanti-fies the local impacts of climate change,especially local water scarcity;and simulates and discusses several proposed methods to combat these impacts.Hydrologic and climatic data are statistically analyzed and VENSIM modeling is used for various simulations of water resources in the basin.Results show that the natural climate changes affecting Kashafroud Basin include increased tempera-ture,less rainfall,more frequent droughts,and changes in rainfall patterns,all of which are local symptoms of climate change in recent years.However,the most important challenge in the basin is the overexploitation of surface and groundwater resources to meet the growing water demands,especially domestic needs.Changes in land use,reallocation of water uses,groundwater depletion,and deg-radation of the quality of surface waters have all contributed to significant changes in the environmental features of this basin,and are the main reason why water demands now exceed the renewal capacity of the basin.Proposed response measures include reallocation of resources among different uses,inter-basin water~ansfers,drawing water from six small dams on the Kashafroud River,reducing groundwater extraction,and replacing groundwater extraction for agriculture by reuse of urban wastewater.This study concludes that although changes in global climatic pararneters have altered environmental features in the basin,local factors,such as water utilization beyond the renewable capacity of the basin,are more significant in worsening the impacts of climate change.展开更多
文摘A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelayer with an average hardness of~HV 1170 is formed.The hardness was increased by WC and TiN reinforcingparticles,dissolved Co atoms in Ti,and the formation of ultrafine grains.WC particles were incorporated into the Tisubstrate owing to the intense frictional interaction/heating at the tool-plate interface(~1000℃),which led to strengthloss and wear of the tool.The Williamson-Hall analysis of the XRD peaks of the SFSed sample confirmed a significantlysmall crystallite size(~100 nm).Wear tests showed that the wear resistance of the composite structure was about 4.5times higher than that of the CP-Ti.Friction analysis revealed a significant reduction in average value and fluctuations ofthe friction coefficient.
文摘This paper assesses the various factors contributing to climate change in the region of the Kashaffoud G-WADI Basin in Iron;quanti-fies the local impacts of climate change,especially local water scarcity;and simulates and discusses several proposed methods to combat these impacts.Hydrologic and climatic data are statistically analyzed and VENSIM modeling is used for various simulations of water resources in the basin.Results show that the natural climate changes affecting Kashafroud Basin include increased tempera-ture,less rainfall,more frequent droughts,and changes in rainfall patterns,all of which are local symptoms of climate change in recent years.However,the most important challenge in the basin is the overexploitation of surface and groundwater resources to meet the growing water demands,especially domestic needs.Changes in land use,reallocation of water uses,groundwater depletion,and deg-radation of the quality of surface waters have all contributed to significant changes in the environmental features of this basin,and are the main reason why water demands now exceed the renewal capacity of the basin.Proposed response measures include reallocation of resources among different uses,inter-basin water~ansfers,drawing water from six small dams on the Kashafroud River,reducing groundwater extraction,and replacing groundwater extraction for agriculture by reuse of urban wastewater.This study concludes that although changes in global climatic pararneters have altered environmental features in the basin,local factors,such as water utilization beyond the renewable capacity of the basin,are more significant in worsening the impacts of climate change.
