The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement,insufficient bearing capacity of soaked foundation,collapse and instability of sub...The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement,insufficient bearing capacity of soaked foundation,collapse and instability of sub-grade side slope due to the special properties of loess.As an environment-friendly,low-cost soil modifier with good adhesion and chelation properties,lignin has been considered to be used in highway subgrade construction.In order to explore the effect of lignin on loess,the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test.The improvement mechanism of lignin on loess collapsibility was studied by means of infiltration test and SEM test.The results show that lignin fibers can promote the agglomeration of loose particles and form a network structure in the soil particle pores,enhance the cementation strength between particles and soil skeleton,and reduce the permeability of loess.With the increase of lignin fiber content,the improvement degree of loess collaps ility shows a trend of first increasing and then decreasing.When the lignin fiber content is 2%,the effect is the best,and the improved loess ollapsi-bility is eliminated.展开更多
There has been a rapidly growing demand for low-cost,integrated single-shot spectrometers to be embedded in portable intelligent devices.Even though significant progress has been made in this area,two major problems a...There has been a rapidly growing demand for low-cost,integrated single-shot spectrometers to be embedded in portable intelligent devices.Even though significant progress has been made in this area,two major problems are still remaining,namely the high temperature sensitivity and poor bandwidth-resolution ratio(BRR)that can’t meet the requirement of most applications.In this work,we present an integrated single-shot spectrometer relying on a silicon photonic circuit that has a footprint less than 3mm2,but could achieve broad operation bandwidth about 100 nm and high resolution up to 0.1 nm(with a BRR~1000).Moreover,for the first time,we demonstrate an integrated spectrometer that could operate within a wide temperature range(between 10 and 70 degrees Celsius)without additional power consumption for temperature management.展开更多
In this study,combining the single point diamond turning(SPDT)and spark plasma sintering(SPS),we achieved high-strength diffusion bonding of copper at an ultra-low temperature of 202℃(0.35 T_(m),T_(m):absolute temper...In this study,combining the single point diamond turning(SPDT)and spark plasma sintering(SPS),we achieved high-strength diffusion bonding of copper at an ultra-low temperature of 202℃(0.35 T_(m),T_(m):absolute temperature of the melting point).Additionally,the closure mechanism of interfacial micro-and nano-voids during the Cu-Cu SPS diffusion bonding is systematically revealed for the first time.For micro-voids,the pulsed current is found to induce additional diffusion flux and plastic deformation,thereby facilitating the void closure.Molecular dynamics(MD)simulation revealed that at the atomic scale,high-energy Cu atoms induced by the pulsed current can significantly promote the diffusion of low-energy atoms in their vicinity and accelerate the void closure.This study also proposes a novel“evaporation-deposition”nano-void closure mechanism for the previously unstudied nano-void closure process.The results show that the synergistic effect of the pulsed current and nanoscale surface rough-ness can significantly improve joint strength.At a low temperature of 405℃(0.5 T_(m)),on combining the computerized numerical control(CNC)turning and SPS diffusion bonding,the joint strength can reach 212 MPa,while that for the joint obtained by traditional hot pressing diffusion bonding at the same tem-perature is only 47 MPa.We obtained an ultra-high joint strength of 271 MPa using the combined process of SPDT and SPS diffusion bonding at an ultra-low temperature of 202℃(0.35 T_(m)),which is approximately 600℃ lower than the traditional diffusion bonding process temperature of 800℃(0.79 T_(m)).To sum up,this study provides a novel method and theoretical support for realizing low-temperature high-strength diffusion bonding.展开更多
The polymer waveguide optical biosensor based on the Mach-Zehnder interferometer （MZI） by using spectral splitting effect is investigated. The MZI based biosensor has two unequal width sensing arms. With the differe...The polymer waveguide optical biosensor based on the Mach-Zehnder interferometer （MZI） by using spectral splitting effect is investigated. The MZI based biosensor has two unequal width sensing arms. With the different mode dispersion responses of the two-arm waveguides to the cladding refractive index change, the spectral splitting effect of the output interference spectrum is obtained, inducing a very high sensitivity. The influence of the different mode dispersions between the two-arm waveguides on the spectral splitting characteristic is analyzed. By choosing different lengths of the two unequal width sensing arms, the initial dip wavelength of the interference spectrum and the spectral splitting range can be controlled flexibly. The polymer waveguide optical biosensor is designed, and its sensing property is analyzed. The results show that the sensitivity of the polymer waveguide optical biosensor by using spectral splitting effect is as high as 10^4nm/RIU, with an improvement of 2-3 orders of magnitude compared with the slot waveguide based microring biosensor.展开更多
基金This work was funded under Funding of Science for Earthquake Resilience(Grant No.XH21034)the Special Fund for Innovation Team,Gansu Earthquake Agency(Grant No.2020TD-01-01)+1 种基金the grant of the National Natural Science Foundation of China(Nos.51778590,51408567)the Fundamental Research Funding for the Institute of Earthquake Forecasting,China Earthquake Administration(Grant Nos.2021IESLZ03,2018IESLZ06).
文摘The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement,insufficient bearing capacity of soaked foundation,collapse and instability of sub-grade side slope due to the special properties of loess.As an environment-friendly,low-cost soil modifier with good adhesion and chelation properties,lignin has been considered to be used in highway subgrade construction.In order to explore the effect of lignin on loess,the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test.The improvement mechanism of lignin on loess collapsibility was studied by means of infiltration test and SEM test.The results show that lignin fibers can promote the agglomeration of loose particles and form a network structure in the soil particle pores,enhance the cementation strength between particles and soil skeleton,and reduce the permeability of loess.With the increase of lignin fiber content,the improvement degree of loess collaps ility shows a trend of first increasing and then decreasing.When the lignin fiber content is 2%,the effect is the best,and the improved loess ollapsi-bility is eliminated.
基金National Key R&D Program of China(grant No.2021YFB2801500)National Natural Science Foundation of China(grant No.62105149,No.62375126)+2 种基金Fundamental Research Funds for the Central Universities(grant No.NS2022043)Provincial Distinguished Professor Fund of Jiangsu,Natural Science Foundation of Jiangsu Province(grant No.BK20210288)State Key Laboratory of Advanced Optical Communication Systems and Networks,China.
文摘There has been a rapidly growing demand for low-cost,integrated single-shot spectrometers to be embedded in portable intelligent devices.Even though significant progress has been made in this area,two major problems are still remaining,namely the high temperature sensitivity and poor bandwidth-resolution ratio(BRR)that can’t meet the requirement of most applications.In this work,we present an integrated single-shot spectrometer relying on a silicon photonic circuit that has a footprint less than 3mm2,but could achieve broad operation bandwidth about 100 nm and high resolution up to 0.1 nm(with a BRR~1000).Moreover,for the first time,we demonstrate an integrated spectrometer that could operate within a wide temperature range(between 10 and 70 degrees Celsius)without additional power consumption for temperature management.
文摘In this study,combining the single point diamond turning(SPDT)and spark plasma sintering(SPS),we achieved high-strength diffusion bonding of copper at an ultra-low temperature of 202℃(0.35 T_(m),T_(m):absolute temperature of the melting point).Additionally,the closure mechanism of interfacial micro-and nano-voids during the Cu-Cu SPS diffusion bonding is systematically revealed for the first time.For micro-voids,the pulsed current is found to induce additional diffusion flux and plastic deformation,thereby facilitating the void closure.Molecular dynamics(MD)simulation revealed that at the atomic scale,high-energy Cu atoms induced by the pulsed current can significantly promote the diffusion of low-energy atoms in their vicinity and accelerate the void closure.This study also proposes a novel“evaporation-deposition”nano-void closure mechanism for the previously unstudied nano-void closure process.The results show that the synergistic effect of the pulsed current and nanoscale surface rough-ness can significantly improve joint strength.At a low temperature of 405℃(0.5 T_(m)),on combining the computerized numerical control(CNC)turning and SPS diffusion bonding,the joint strength can reach 212 MPa,while that for the joint obtained by traditional hot pressing diffusion bonding at the same tem-perature is only 47 MPa.We obtained an ultra-high joint strength of 271 MPa using the combined process of SPDT and SPS diffusion bonding at an ultra-low temperature of 202℃(0.35 T_(m)),which is approximately 600℃ lower than the traditional diffusion bonding process temperature of 800℃(0.79 T_(m)).To sum up,this study provides a novel method and theoretical support for realizing low-temperature high-strength diffusion bonding.
基金This work was supported in part by the International Science ＆ Technology Cooperation Program of China （No. 2014DFG32590）, National Natural Science Foundation of China （No. 61307040）, National R＆D Program （No. 2012AA040406）, National Research Foundation of China （No. 6140450010305）, Natural Science Foundation of Liaoning Province （No. 2014020002）, and Fundamental Research Funds for the Central Universities （DUT 15ZD231 and DUT2015TD47）.
文摘The polymer waveguide optical biosensor based on the Mach-Zehnder interferometer （MZI） by using spectral splitting effect is investigated. The MZI based biosensor has two unequal width sensing arms. With the different mode dispersion responses of the two-arm waveguides to the cladding refractive index change, the spectral splitting effect of the output interference spectrum is obtained, inducing a very high sensitivity. The influence of the different mode dispersions between the two-arm waveguides on the spectral splitting characteristic is analyzed. By choosing different lengths of the two unequal width sensing arms, the initial dip wavelength of the interference spectrum and the spectral splitting range can be controlled flexibly. The polymer waveguide optical biosensor is designed, and its sensing property is analyzed. The results show that the sensitivity of the polymer waveguide optical biosensor by using spectral splitting effect is as high as 10^4nm/RIU, with an improvement of 2-3 orders of magnitude compared with the slot waveguide based microring biosensor.
