Bedrock and concrete lining are typical composite structures in the engineering field and the stability of the geological body and engineering body is directly connected to the mechanical properties of the composite b...Bedrock and concrete lining are typical composite structures in the engineering field and the stability of the geological body and engineering body is directly connected to the mechanical properties of the composite body.Under this background,the study provides the transverse isotropic equivalent model of concrete-granite double-layer composite based on the notion of strain energy equivalence.Assuming that the strength failure of concrete and granite meets the Mohr-Coulomb criterion,then the strength failure model of the combined body considering the joint roughness coefficient(JRC)is derived,and the influences of JRC,the height ratio of concrete to granite,and confining pressure on the strength failure characteristics of the combined body are emphatically analyzed.Finally,the model applicability is illustrated by the uniaxial and triaxial compression tests on concrete monomer,granite monomer and concretegranite composite samples(CGCSs)with different JRCs.The results revealed that the compressive strength of the composite is closer to the concrete with lower strength in the combined body under different confining pressures.Adding interface roughness causes to raise the compressive strength of the composite due to interfacial adhesion between concrete and granite,and a slowing growth trend is observed in compressive strength as roughness.The model can provide a certain reference for the stability design and evaluation of engineering rock mass.展开更多
This article describes a process for the synthesis of diethyl oxalate by a coupling reaction of carbon monoxide, catalyzed by palladium in the presence of ethyl nitrite. The kinetics and mechanism of the coupling and ...This article describes a process for the synthesis of diethyl oxalate by a coupling reaction of carbon monoxide, catalyzed by palladium in the presence of ethyl nitrite. The kinetics and mechanism of the coupling and regeneration reaction are also discussed. This paper presents the results of a scale-up test of the catalyst and the process based on an a priori computer simulation.展开更多
Background and Originality Content Hydrogels,which retain a large amount of water,possess tunable porous three-dimensional nanostructure.They are known to resemble human tissue that can offer many advantages in biomed...Background and Originality Content Hydrogels,which retain a large amount of water,possess tunable porous three-dimensional nanostructure.They are known to resemble human tissue that can offer many advantages in biomedical applications such as tissue engineering,drug delivery and surgical dressings.1141 Stimuli-responsive hydrogels,referred as smart hydrogels can rapidly respond in a controlled manner to external stimuli,such as temperature,pH,light,etc.[s]In particular,the thermal-responsive hydrogels exhibit sol-to-gel phase transition upon heating up to lower critical gelation temperatures(CGTs).展开更多
Plant phenology is a key parameter for accurately modeling ecosystem dynamics.Limited by scarce ground observations and benefiting from the rapid growth of satellite-based Earth observations,satellite data have been w...Plant phenology is a key parameter for accurately modeling ecosystem dynamics.Limited by scarce ground observations and benefiting from the rapid growth of satellite-based Earth observations,satellite data have been widely used for broad-scale phenology studies.Commonly used reflectance vegetation indices represent the emergence and senescence of photosynthetic structures(leaves),but not necessarily that of photosynthetic activities.Leveraging data of the recently emerging solar-induced chlorophyll fluorescence(SIF)that is directly related to photosynthesis,and the traditional MODIS Normalized Difference Vegetation Index(NDVI),we investigated the similarities and differences on the start and end of the growing season(SOS and EOS,respectively)of the Tibetan Plateau.We found similar spatiotemporal patterns in SIF-based SOS(SOS_(SIF))and NDVI-based SOS(SOS_(NDV)I).These spatial patterns were mainly driven by temperature in the east and by precipitation in the west.Yet the two satellite products produced different spatial patterns in EOS,likely due to their different climate dependencies.Our work demonstrates the value of big Earth data for discovering broad-scale spatiotemporal patterns,especially on regions with scarce field data.This study provides insights into extending the definition of phenology and fosters a deeper understanding of ecosystem dynamics from big data.展开更多
This paper presents a computational investigation of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser operated in a novel operating mode of low temperature contact and high catalyst-to-oil ratio...This paper presents a computational investigation of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser operated in a novel operating mode of low temperature contact and high catalyst-to-oil ratio. Through incorporating feedstock vaporization and a 12-lump cracking kinetics model, a validated gas-solid flow model has been extended to the analysis of the hydrodynamic and reaction behavior in an industrial riser. The results indicate that the hydrodynamics, temperature and species concentration exhibit significantly nonuniform behavior inside the riser, especially in the atomization nozzle region. The lump concentration profiles along the riser height provide useful information for riser optimization. Compared to conventional fluid catalytic cracking (FCC) process, feedstock conversion and gasoline yield are respectively increased by 1.9 units and 1.0 unit in the new FCC process, the yield of liquefied petroleum gas is increased by about 1.0 unit while dry gas yield is reduced by about 0.3 unit.展开更多
基金The authors would like to acknowledge financial supports from the National Natural Science Foundation of China(Nos.41941019 and 52274145)Department of Science and Technology of Shaanxi Province(No.2021TD-55)+2 种基金“111”Center,Program of the Ministry of Education of China(No.B18046)Natural Science Foundation of Shaanxi Province(No.2020JQ-373)the Fundamental Research Funds for the Central Universities,CHD(No.300102261101).
文摘Bedrock and concrete lining are typical composite structures in the engineering field and the stability of the geological body and engineering body is directly connected to the mechanical properties of the composite body.Under this background,the study provides the transverse isotropic equivalent model of concrete-granite double-layer composite based on the notion of strain energy equivalence.Assuming that the strength failure of concrete and granite meets the Mohr-Coulomb criterion,then the strength failure model of the combined body considering the joint roughness coefficient(JRC)is derived,and the influences of JRC,the height ratio of concrete to granite,and confining pressure on the strength failure characteristics of the combined body are emphatically analyzed.Finally,the model applicability is illustrated by the uniaxial and triaxial compression tests on concrete monomer,granite monomer and concretegranite composite samples(CGCSs)with different JRCs.The results revealed that the compressive strength of the composite is closer to the concrete with lower strength in the combined body under different confining pressures.Adding interface roughness causes to raise the compressive strength of the composite due to interfacial adhesion between concrete and granite,and a slowing growth trend is observed in compressive strength as roughness.The model can provide a certain reference for the stability design and evaluation of engineering rock mass.
文摘This article describes a process for the synthesis of diethyl oxalate by a coupling reaction of carbon monoxide, catalyzed by palladium in the presence of ethyl nitrite. The kinetics and mechanism of the coupling and regeneration reaction are also discussed. This paper presents the results of a scale-up test of the catalyst and the process based on an a priori computer simulation.
基金This work was supported by the National Basic Research Program of China(Nos.2015CB931900,2012CB215500)the National Natural Science Foundation of China(Nos.21632009,21421002)+2 种基金the Key Program of the Chinese Academy of Sciences(No.KGZD-EW-T08)the Key Research Program of Frontier Sciences of CAS(No.QYZDJ-SSWSLH049)the Shanghai Rising-Star Program(No.16QA1404600)for financial support.
文摘Background and Originality Content Hydrogels,which retain a large amount of water,possess tunable porous three-dimensional nanostructure.They are known to resemble human tissue that can offer many advantages in biomedical applications such as tissue engineering,drug delivery and surgical dressings.1141 Stimuli-responsive hydrogels,referred as smart hydrogels can rapidly respond in a controlled manner to external stimuli,such as temperature,pH,light,etc.[s]In particular,the thermal-responsive hydrogels exhibit sol-to-gel phase transition upon heating up to lower critical gelation temperatures(CGTs).
基金This study was supported by the National Natural Science Foundation of China(41861134036,41988101)by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0405)。
文摘Plant phenology is a key parameter for accurately modeling ecosystem dynamics.Limited by scarce ground observations and benefiting from the rapid growth of satellite-based Earth observations,satellite data have been widely used for broad-scale phenology studies.Commonly used reflectance vegetation indices represent the emergence and senescence of photosynthetic structures(leaves),but not necessarily that of photosynthetic activities.Leveraging data of the recently emerging solar-induced chlorophyll fluorescence(SIF)that is directly related to photosynthesis,and the traditional MODIS Normalized Difference Vegetation Index(NDVI),we investigated the similarities and differences on the start and end of the growing season(SOS and EOS,respectively)of the Tibetan Plateau.We found similar spatiotemporal patterns in SIF-based SOS(SOS_(SIF))and NDVI-based SOS(SOS_(NDV)I).These spatial patterns were mainly driven by temperature in the east and by precipitation in the west.Yet the two satellite products produced different spatial patterns in EOS,likely due to their different climate dependencies.Our work demonstrates the value of big Earth data for discovering broad-scale spatiotemporal patterns,especially on regions with scarce field data.This study provides insights into extending the definition of phenology and fosters a deeper understanding of ecosystem dynamics from big data.
基金supports by National Natural Science Foundation of China (Nos. 51025624 and 20976191)111 Project (B12034)Fundamental Research Funds for the Central Universities (11QG26)
文摘This paper presents a computational investigation of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser operated in a novel operating mode of low temperature contact and high catalyst-to-oil ratio. Through incorporating feedstock vaporization and a 12-lump cracking kinetics model, a validated gas-solid flow model has been extended to the analysis of the hydrodynamic and reaction behavior in an industrial riser. The results indicate that the hydrodynamics, temperature and species concentration exhibit significantly nonuniform behavior inside the riser, especially in the atomization nozzle region. The lump concentration profiles along the riser height provide useful information for riser optimization. Compared to conventional fluid catalytic cracking (FCC) process, feedstock conversion and gasoline yield are respectively increased by 1.9 units and 1.0 unit in the new FCC process, the yield of liquefied petroleum gas is increased by about 1.0 unit while dry gas yield is reduced by about 0.3 unit.