Drought stress is an important factor affecting plant growth and development.It will provide a theoretical basis for cultivating new stress-resistant varieties and improving water utilization rate of plants by studyin...Drought stress is an important factor affecting plant growth and development.It will provide a theoretical basis for cultivating new stress-resistant varieties and improving water utilization rate of plants by studying the regulation mechanism of osmotic adjustment and water transportation under drought stress,and understanding the physiological and biochemical characteristics and stress resistance mechanism.展开更多
Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,a...Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.展开更多
With the deepening of oil and gas exploration,the importance of depth is increasingly highlighted.The risk of preservation of storage space in deep reservoirs is greater than that in shallow and medium layers.Deep lay...With the deepening of oil and gas exploration,the importance of depth is increasingly highlighted.The risk of preservation of storage space in deep reservoirs is greater than that in shallow and medium layers.Deep layers mean older strata,more complex structural evolution and more complex hydrocarbon accumulation processes,and even adjustment and transformation of oil and gas reservoirs.This paper systematically investigates the current status and research progress of deep oil and gas exploration around the world and looks forward to the future research focus of deep oil and gas.In the deep,especially the ultra-deep layers,carbonate reservoirs play a more important role than clastic rocks.Karst,fault-karst and dolomite reservoirs are the main types of deep and ultra-deep reservoirs.The common feature of most deep large and medium-sized oil and gas reservoirs is that they formed in the early with shallow depth.Fault activity and evolution of trap highs are the main ways to cause physical adjustment of oil and gas reservoirs.Crude oil cracking and thermochemical sulfate reduction(TSR)are the main chemical modification effects in the reservoir.Large-scale high-quality dolomite reservoirs is the main direction of deep oil and gas exploration.Accurate identification of oil and gas charging,adjustment and reformation processes is the key to understanding deep oil and gas distribution.High-precision detection technology and high-precision dating technology are an important guarantee for deep oil and gas research.展开更多
Worldwide trends in mobile electrification will skyrocket demands for lithium-based battery production,driven by the popularity of electric vehicles.However,both lithium metal batteries and lithium ion batteries face ...Worldwide trends in mobile electrification will skyrocket demands for lithium-based battery production,driven by the popularity of electric vehicles.However,both lithium metal batteries and lithium ion batteries face severe safety issues due to dendrite nucleation and growth process.Li deposition is significantly influenced by interfacial factors and charging conditions.In this paper,an electrochemical model considering the internal and external factors is proposed based on Monte Carlo method.The influence of internal solid electrolyte interphase(SEI)porosity,thickness and the external conditions on dendrite growth process is systematically described.The simulation results support that the three factors investigated in this model could synergistically regulate the dendrite growth process.Three competition mechanisms are proposed to tailor lithium deposition for Li-based batteries and numerical solutions for variation pattern of dendrite growth with time are fitted.A three-step process describing kinetic process of lithium deposition is proposed.To achieve dendrite-free charging process,charging strategies and emerging materials design should be considered,including physicochemical materials engineering,artificial SEI,and design for dynamic safety boundary.This work could contribute to the foundation for insights of Li deposition mechanism,which is promising to provide guidelines for next-generation high-energy-density and safe batteries in CHAIN framework.展开更多
An asymmetric actuated 3-PPPS parallel mechanism was analyzed in its application to an aircraft wing adjustment process.The posture alignment precision at the wing ends was enhanced with a kinematic calibration method...An asymmetric actuated 3-PPPS parallel mechanism was analyzed in its application to an aircraft wing adjustment process.The posture alignment precision at the wing ends was enhanced with a kinematic calibration method.A constraint equation was built based on a constraint condition that distances among spherical joints of the mechanism were constant,and further eight groups of analytic forward solutions of all poses of the mechanism were solved.An inverse equation of the posture alignment displacements of aircraft wing parts was built based on space vector chains,and a mapping equation of the pose and geometric errors of the posture alignment mechanism containing 39 error sources was derived by differentiating the kinematic equation of the mechanism.After kinematic calibration experiments,the maximum position error of the posture alignment platform dropped from 2.67 mm to 0.82 mm,the maximum angle error decreased from 0.481° to 0.167°,and the posture alignment precision of the aircraft wing end was improved.展开更多
The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer solution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandst...The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer solution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandstone reservoirs in EOR projects.To alleviate the matching problems between the layer permeability and the injected polymer molecular weight,a molecular weight adjusting device with porous medium was designed on the basis of mechanical degradation principle.In terms of four variables(polymer concentration,pore diameter,length of shear component and flow rate),the rheological behavior of hydrolyzed polyacrylamide(HPAM)solution flowing through the device was investigated in detail.The change of these variables is able to control the shear rate of HPAM solutions through ceramic foam,and achieve the desired degree of shear degradation and the final rheological parameters—viscosity loss,viscoelasticity and pressure drop.Therefore,a linear relationship between viscosity loss and shearing rate was established so as to obtain the targeted viscosity easily.Field tests in the Daqing Oil Field showed that the polymer molecular weight could drop 20%to 50%.In a word,the results could guide the industrial application of the novel device and the further study of polymer degradation flowing through the porous medium.展开更多
基金Supported by Thousand Talents Program for High-end Innovative Talents of Qinghai Province(2020,2022).
文摘Drought stress is an important factor affecting plant growth and development.It will provide a theoretical basis for cultivating new stress-resistant varieties and improving water utilization rate of plants by studying the regulation mechanism of osmotic adjustment and water transportation under drought stress,and understanding the physiological and biochemical characteristics and stress resistance mechanism.
基金supported by the National Natural Science Foundation of China under Grant No.52072196,52002199,52002200,52102106Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No.ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No.ZR2019BEM042,ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No.2020KJA004the Taishan Scholars Program of Shandong Province under No.ts201511034
文摘Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.
基金This study was funded by Innovative Research Groups of the National Natural Science Foundation of China(Grant No.41821002)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA14010305)PetroChina Major Science and Technology Project(Grant No.ZD2019-183-002).
文摘With the deepening of oil and gas exploration,the importance of depth is increasingly highlighted.The risk of preservation of storage space in deep reservoirs is greater than that in shallow and medium layers.Deep layers mean older strata,more complex structural evolution and more complex hydrocarbon accumulation processes,and even adjustment and transformation of oil and gas reservoirs.This paper systematically investigates the current status and research progress of deep oil and gas exploration around the world and looks forward to the future research focus of deep oil and gas.In the deep,especially the ultra-deep layers,carbonate reservoirs play a more important role than clastic rocks.Karst,fault-karst and dolomite reservoirs are the main types of deep and ultra-deep reservoirs.The common feature of most deep large and medium-sized oil and gas reservoirs is that they formed in the early with shallow depth.Fault activity and evolution of trap highs are the main ways to cause physical adjustment of oil and gas reservoirs.Crude oil cracking and thermochemical sulfate reduction(TSR)are the main chemical modification effects in the reservoir.Large-scale high-quality dolomite reservoirs is the main direction of deep oil and gas exploration.Accurate identification of oil and gas charging,adjustment and reformation processes is the key to understanding deep oil and gas distribution.High-precision detection technology and high-precision dating technology are an important guarantee for deep oil and gas research.
基金the financial supports from the National Natural Science Foundation of China(52102470)。
文摘Worldwide trends in mobile electrification will skyrocket demands for lithium-based battery production,driven by the popularity of electric vehicles.However,both lithium metal batteries and lithium ion batteries face severe safety issues due to dendrite nucleation and growth process.Li deposition is significantly influenced by interfacial factors and charging conditions.In this paper,an electrochemical model considering the internal and external factors is proposed based on Monte Carlo method.The influence of internal solid electrolyte interphase(SEI)porosity,thickness and the external conditions on dendrite growth process is systematically described.The simulation results support that the three factors investigated in this model could synergistically regulate the dendrite growth process.Three competition mechanisms are proposed to tailor lithium deposition for Li-based batteries and numerical solutions for variation pattern of dendrite growth with time are fitted.A three-step process describing kinetic process of lithium deposition is proposed.To achieve dendrite-free charging process,charging strategies and emerging materials design should be considered,including physicochemical materials engineering,artificial SEI,and design for dynamic safety boundary.This work could contribute to the foundation for insights of Li deposition mechanism,which is promising to provide guidelines for next-generation high-energy-density and safe batteries in CHAIN framework.
基金supported by the National Natural Science Foundation of China (No.51275234)the Aeronautical Science Foundation of China(No.20131652027)
文摘An asymmetric actuated 3-PPPS parallel mechanism was analyzed in its application to an aircraft wing adjustment process.The posture alignment precision at the wing ends was enhanced with a kinematic calibration method.A constraint equation was built based on a constraint condition that distances among spherical joints of the mechanism were constant,and further eight groups of analytic forward solutions of all poses of the mechanism were solved.An inverse equation of the posture alignment displacements of aircraft wing parts was built based on space vector chains,and a mapping equation of the pose and geometric errors of the posture alignment mechanism containing 39 error sources was derived by differentiating the kinematic equation of the mechanism.After kinematic calibration experiments,the maximum position error of the posture alignment platform dropped from 2.67 mm to 0.82 mm,the maximum angle error decreased from 0.481° to 0.167°,and the posture alignment precision of the aircraft wing end was improved.
基金Supported by the Program for Yangtse River Scholars and Innovative Research Terms in Universities(IRT0936)the National Basic Research Program of China(2009CB219905+2 种基金2009CB219907)the Daqing Oilfield Co.Ltd
文摘The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer solution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandstone reservoirs in EOR projects.To alleviate the matching problems between the layer permeability and the injected polymer molecular weight,a molecular weight adjusting device with porous medium was designed on the basis of mechanical degradation principle.In terms of four variables(polymer concentration,pore diameter,length of shear component and flow rate),the rheological behavior of hydrolyzed polyacrylamide(HPAM)solution flowing through the device was investigated in detail.The change of these variables is able to control the shear rate of HPAM solutions through ceramic foam,and achieve the desired degree of shear degradation and the final rheological parameters—viscosity loss,viscoelasticity and pressure drop.Therefore,a linear relationship between viscosity loss and shearing rate was established so as to obtain the targeted viscosity easily.Field tests in the Daqing Oil Field showed that the polymer molecular weight could drop 20%to 50%.In a word,the results could guide the industrial application of the novel device and the further study of polymer degradation flowing through the porous medium.
