Due to its impact on cereal yields,vegetation growth,animal wellbeing,and human health,considerable attention has been paid to diurnal temperature range,focusing on the temporal dimension of surface air temperature.Ho...Due to its impact on cereal yields,vegetation growth,animal wellbeing,and human health,considerable attention has been paid to diurnal temperature range,focusing on the temporal dimension of surface air temperature.However,the characteristics of spatial temperature range and its response to climate change remain unclear,despite its importance to various natural and societal activities.Here,we proposed a daily spatial temperature range(DSTR,difference between spatial maximum and minimum temperature,STmax and STmin)indicator to measure the maximum spatial temperature range within a given region over a day.We analyzed the spatiotemporal pattern of DSTR and its trend under climate change at four scales(global,hemispheric,national,and provincial),with the following main results:(1)DSTR was scale dependent,provincial pattern of which were mainly related to sensible and latent heat fluxes.(2)The key regions affecting DSTR and temporal distribution at different scales were mapped out.(3)Under climate change,DSTR significantly decreased globally,hemispherically,and in several Chinese provinces due to the greater warming of STmin than STmax.The influence of latent heat flux and solar shortwave radiation was larger at global/hemispheric scales,while the albedo was a more critical driver at provincial scale.For the first time,we proposed the DSTR indicator and emphasized the importance of exploring spatial temperature heterogeneity.This spatial information is important to optimize relevant societal activities,and the response of DSTR to climate change has further led to the consideration of the relationship between DSTR and extreme events,biodiversity,etc.展开更多
The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron ...The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） equipped with energy dispersive spectroscope （EDS）, and transmission electron microscopy （TEM）. The typical solidification characteristics are due to the joint influence of both the crystal temperature range and the solidification path. The wide crystallization temperature range contributes to obtaining coarse dendrites in the as-cast Ti47A17Nb2.5V1.0Cr （at%） alloy solidifying through the peritectic reaction. The β-solidifying Ti46A17Nb2.5V1.0Cr （at%） alloy with the narrow crystallization temperature range is attributed to the formation of a homogeneous finegrained microstructure. However, the crystallization temperature range of Ti48A17Nb2.5V1.0Cr （at%） alloy is equivalent to that of Ti46A17Nb2.5V1.0Cr alloy, but it is solidified by peritectic reaction, leading to the formation of finer dendrites.展开更多
We report the magnetostrictive performance of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites.Measurement of M?ssbauer spectra and the XRD results indicate that the easy magnetic direction of the Nd_(0.2)Tb_(0....We report the magnetostrictive performance of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites.Measurement of M?ssbauer spectra and the XRD results indicate that the easy magnetic direction of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)compound is along<111>direction with spontaneous magnetostrictionλ111 of1900 ppm.The<111>-oriented Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites with particle volume fractions of20 vol%-55 vol%were prepared.Magnetization measurements demonstrate that the composite is highly anisotropic.The raw material cost of Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)is about 85%of that of the Terfenol-D(Tb_(0.3)Dy_(0.7)Fe_(2))composition.Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites possess comparable magnetostriction with those composites made of Tb_(0.3)Dy_(0.7)Fe_(2)particles.At room temperature,the magnetostrictionλ_Ⅱof the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composite reaches 420 ppm at a low field of 80 kA/m and about1000 ppm at 239 kA/m.In addition,the composite exhibits a large saturation magnetostrictionλ_Ⅱover1200 ppm from 300 to 100 K,suggesting its potential applications as a low-cost magnetostrictive material in a wide temperature range.Therefore,the current study offers an opportunity to widen the operating temperature range of the magnetostrictive composite.展开更多
基金the financial support from the National Key Research and Development Program of China(Grant No.2023YFB3907402)the Strategic Priority Research Program of the Chinese Academy of Sciences(Category B,Geographic Intelligence,Grant No.XDB0740300)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant No.GZC20241691).
文摘Due to its impact on cereal yields,vegetation growth,animal wellbeing,and human health,considerable attention has been paid to diurnal temperature range,focusing on the temporal dimension of surface air temperature.However,the characteristics of spatial temperature range and its response to climate change remain unclear,despite its importance to various natural and societal activities.Here,we proposed a daily spatial temperature range(DSTR,difference between spatial maximum and minimum temperature,STmax and STmin)indicator to measure the maximum spatial temperature range within a given region over a day.We analyzed the spatiotemporal pattern of DSTR and its trend under climate change at four scales(global,hemispheric,national,and provincial),with the following main results:(1)DSTR was scale dependent,provincial pattern of which were mainly related to sensible and latent heat fluxes.(2)The key regions affecting DSTR and temporal distribution at different scales were mapped out.(3)Under climate change,DSTR significantly decreased globally,hemispherically,and in several Chinese provinces due to the greater warming of STmin than STmax.The influence of latent heat flux and solar shortwave radiation was larger at global/hemispheric scales,while the albedo was a more critical driver at provincial scale.For the first time,we proposed the DSTR indicator and emphasized the importance of exploring spatial temperature heterogeneity.This spatial information is important to optimize relevant societal activities,and the response of DSTR to climate change has further led to the consideration of the relationship between DSTR and extreme events,biodiversity,etc.
基金financially supported by the National Basic Research Program of China(No.2011CB605503)the Program of Introducing Talents of Discipline to Universities(No.B08040)
文摘The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） equipped with energy dispersive spectroscope （EDS）, and transmission electron microscopy （TEM）. The typical solidification characteristics are due to the joint influence of both the crystal temperature range and the solidification path. The wide crystallization temperature range contributes to obtaining coarse dendrites in the as-cast Ti47A17Nb2.5V1.0Cr （at%） alloy solidifying through the peritectic reaction. The β-solidifying Ti46A17Nb2.5V1.0Cr （at%） alloy with the narrow crystallization temperature range is attributed to the formation of a homogeneous finegrained microstructure. However, the crystallization temperature range of Ti48A17Nb2.5V1.0Cr （at%） alloy is equivalent to that of Ti46A17Nb2.5V1.0Cr alloy, but it is solidified by peritectic reaction, leading to the formation of finer dendrites.
基金Project supported by the National Natural Science Foundation of China(11475086,51671102)Project-based Courses in NUAA(20210849A)。
文摘We report the magnetostrictive performance of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites.Measurement of M?ssbauer spectra and the XRD results indicate that the easy magnetic direction of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)compound is along<111>direction with spontaneous magnetostrictionλ111 of1900 ppm.The<111>-oriented Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites with particle volume fractions of20 vol%-55 vol%were prepared.Magnetization measurements demonstrate that the composite is highly anisotropic.The raw material cost of Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)is about 85%of that of the Terfenol-D(Tb_(0.3)Dy_(0.7)Fe_(2))composition.Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites possess comparable magnetostriction with those composites made of Tb_(0.3)Dy_(0.7)Fe_(2)particles.At room temperature,the magnetostrictionλ_Ⅱof the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composite reaches 420 ppm at a low field of 80 kA/m and about1000 ppm at 239 kA/m.In addition,the composite exhibits a large saturation magnetostrictionλ_Ⅱover1200 ppm from 300 to 100 K,suggesting its potential applications as a low-cost magnetostrictive material in a wide temperature range.Therefore,the current study offers an opportunity to widen the operating temperature range of the magnetostrictive composite.
