Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigati...Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.展开更多
Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by us...Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.展开更多
In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engin...In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.展开更多
Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive s...Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.展开更多
Due to the mechanical stability of the PP layer,the oriented PP/PE double-layer film with a row-nucleated crystalline structure can be annealed at a higher temperature than the PE monolayer film.In this work,the effec...Due to the mechanical stability of the PP layer,the oriented PP/PE double-layer film with a row-nucleated crystalline structure can be annealed at a higher temperature than the PE monolayer film.In this work,the effects of annealing temperature within the melting range of PE on the crystalline structure and properties of PP/PE double-layer films were studied.When the annealing temperature is between 100 and 130℃,below the melting point of PE,the crystallinity,the long period,lateral dimension and orientation of the lamellae in the PE layer increase with the annealing temperature due to the melting of thin lamellae and the self-nucleated effect of partially-melted melts during annealing.With the annealing temperature further increasing to 138℃,near the melting ending point of PE,since the lamellae melt completely and the melt memory becomes weak during annealing,some spherulite structures are formed in the annealed sample,resulting in a decrease of orientation.In contrast,the annealing only causes the appearance of a low-temperature endothermic plateau in the PP layer.The improved size and orientation of lamellar structure in the PE layer increase the pore arrangement and porosity of the stretched PP/PE microporous membrane.This study successfully applies the self-nucleation effect of partially-melted polymer melt into the practical annealing process,which is helpful to guide the production of high-performance PP/PE/PP lithium batteries separator and the annealing process of other multilayer products.展开更多
Microwave absorption properties of the nanocrystalline strontium ferrite （SrFe12O19） and iron （α-Fe） microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz 18 GHz....Microwave absorption properties of the nanocrystalline strontium ferrite （SrFe12O19） and iron （α-Fe） microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz 18 GHz. For the singlelayer absorbers, the nanocrystalline SrFe12O19 microfibers show some microwave absorptions at 6 GHz 18 GHz, with a minimum reflection loss （RL） value of -11.9 dB at 14.1 GHz for a specimen thickness of 3.0 mm, while for the nanocrystalline α-Fe microfibers, their absorptions largely take place at 15 GHz-18 GHz with the RL value exceeding -10 dB, with a minimum .RL value of about -24 dB at 17.5 GHz for a specimen thickness of 0.7 mm. For the doublelayer absorber with an absorbing layer of α-Fe microfibers with a thickness of 0.7 mm and matching layer of SrFe12O19 microfibers with a thickness of 1.3 ram, the minimum RL value is about -63 dB at 16.4 GHz and the absorption band width is about 6.7 GHz ranging from 11.3 GHz to 18 GHz with the RL value exceeding -10 dB which covers the whole Ku-band （12.4 GHz 18 GHz） and 27% of X-band （8.2 GHz 12.4 GHz）.展开更多
To develop the microwave absorbing(MA)properties of cementitious material mixed with mine solid waste,the iron tailings cementitious microwave absorbing materials were prepared.The iron tailings was treated into diffe...To develop the microwave absorbing(MA)properties of cementitious material mixed with mine solid waste,the iron tailings cementitious microwave absorbing materials were prepared.The iron tailings was treated into different particle sizes by planetary ball mill,and the physicochemical properties of iron tailings were tested by laser particle size analyzer and scanning electron microscope(SEM).The electromagnetic parameters of iron tailings cementitious materials were characterized by a vector network analyzer and simulated MA properties,and the MA properties of iron tailings-cement composite system with steel fiber as absorber was studied.Based on the design of the single-layer structure,optimum mix ratio and thickness configuration method of double-layer structure were further studied,meanwhile,the mechanical properties and engineering application were analyzed and discussed.The results show that the particle size of iron tailings can afiect its electromagnetic behavior in cementitious materials,and the smaller particles lead the increase of demagnetisation efiect induced by domain wall motion and achieve better microwave absorbing properties in cementitious materials.When the thickness of matching layer and absorbing layer is 5 mm,the optimized microwave absorbing properties of C1/C3 double-layer cementitious material can obtain optimal RL value of-27.61 dB and efiective absorbing bandwidth of 0.97 GHz,which attributes to the synergistic efiect of impedance matching and attenuation characteristics.The double-layer microwave absorbing materials obtain excellent absorbing properties and show great design flexibility and diversity,which can be used as a suitable candidate for the preparation of favorable microwave absorbing cementitious materials.展开更多
Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material co...Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.展开更多
Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of ace...Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82 × 10^-3 Ω. cm and particle grains. The doublelayers structure is designed to fabricate the ZnO：In thin film with low resistivity （2.58 × 10^-3 Ω. cm） and good surface morphology. It is found that the surface morphology of the double-layer ZnO：In film strongly depends on the substratelayer, and the second-layer plays a large part in the resistivity of the doublewlayer ZnO：In thin film. Both total and direct transmittances of the double-layer ZnO：In film are above 80% in the visible light region. Single junction a-Si：H solar cell based on the double-layer ZnO：In as front electrode is also investigated.展开更多
Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair.In this work,T-ZnO_(w) enhanced biphasic calcium phosphate(BCP)scaffolds with triply periodic minimal surfac...Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair.In this work,T-ZnO_(w) enhanced biphasic calcium phosphate(BCP)scaffolds with triply periodic minimal surface(TPMS)-based double-layer porous structure were fabricated by digital light processing(DLP)with high precision.Property of suspension was first discussed to obtain better printing quality.After sintering,T-ZnO_(w) reacts with b-tricalcium phosphate(β-TCP)to form Ca_(19)Zn_(2)(PO_(4))14,and inhibits the phase transition toα-TCP.With the content of T-ZnO_(w) increasing from 0 to 2 wt%,the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress,and have the effect of pulling out as well as fracture toughening.However,excessive whiskers will reduce the cure depth,and cause more printing defects,thus reducing the mechanical strength.Besides,T-ZnO_(w) accelerates the deposition of apatite,and the sample with 2 wt%T-ZnO_(w) shows the fastest mineralization rate.The good biocompatibility has been proved by cell proliferation test.Results confirmed that doping T-ZnO_(w) can improve the mechanical strength of BCP scaffolds,and keep good biological property,which provides a new strategy for better bone repair.展开更多
The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interac...The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interaction numerical methods including Fluid FEM and Fluid BEM were used in this case. The comparison of numerical and theoretical results by the present method shows that ANSYS/Fluid80 is more credible, the NASTRAN/Virtual Mass Method is more suitable for engineering calculations and results of the same-phase vibration by the present method is more accurate.展开更多
The micro-perforated panel(MPP)structure has been widely used in various noise control applications,and thus its acoustic performance prediction has been receiving increasing attention.The acoustic performance of simp...The micro-perforated panel(MPP)structure has been widely used in various noise control applications,and thus its acoustic performance prediction has been receiving increasing attention.The acoustic performance of simple MPP structures,such as a MPPsound absorber,has been predicted using an analytical calculation method.However,this is not a suitable approach toward predicting the acoustic performance of complicated MPP structures,owing to the structural complexity of these structures.Moreover,the many perforations of submillimeter scale diameter render the MPP structures very difficult to analyze using numerical simulation.Thus,this study focused on two different simplified MPP simulation methods:the transfer admittance method and the equivalent fluid method,and their application on double-layer MPP structures.Based on the two simplified MPP simulation methods,the transmission loss value of the double-layer MPP mufflers with two sets of different structural parameters was calculated,respectively.The predicted results were compared with the impedance tube measurements.The results revealed that the two simplified MPP simulation methods could effectively predict the acoustic performance of doublelayer MPP structures.Moreover,the prediction based on the transfer admittance method can outperform the two simplified simulation methods.展开更多
Double-layered thermal barrier coatings(DL-TBCs)have been developed to meet multiple service requirements,such as low thermal conductivity,high thermal stability,and high fracture toughness.Conventional DL-TBCs are of...Double-layered thermal barrier coatings(DL-TBCs)have been developed to meet multiple service requirements,such as low thermal conductivity,high thermal stability,and high fracture toughness.Conventional DL-TBCs are often designed on the basis of equal total thickness to have long lifespans,which may weaken the thermal insulation.The reason is that the single-scale designed structure often has opposite effects on the thermal and mechanical properties.To enhance both the thermal insulation and lifespan,this work designed durable DL-TBCs at multiple scales under equivalent thermal insulation.The macroscopic thickness ratio of the top layer to the bottom layer was tailored to optimize the total and single thicknesses,and the microscopic pore size in the top layer was tailored to resist sintering.Six groups of samples with different thickness ratios were prepared.The thermal cycling test revealed that the lifespan of DL-TBCs first increases but then decreases with increasing thickness ratio.The optimized thickness ratio is 2:3 for DL-TBCs,which have the largest lifespan among the six groups.The cross-sectional morphologies revealed that the failure mode changed from the spallation of the top layer to the delamination of the total double layers.The long lifespan of the optimized DL-TBCs stems from the cotailored thickness ratio and porous structure in the top layer to lower the total cracking driving force.展开更多
A modification of the Monin-Obukhov theory is proposed,introducing a two-layer model of the convective atmospheric surface layer(ASL)with a fixed interlayer boundary.The convective ASL is assumed to consist of a frict...A modification of the Monin-Obukhov theory is proposed,introducing a two-layer model of the convective atmospheric surface layer(ASL)with a fixed interlayer boundary.The convective ASL is assumed to consist of a frictional-heat sublayer,adjacent to the underlying surface,and a forced-convection sublayer.Approximations of the turbulent moments are derived independently for each sublayer in the form of truncated Taylor expansions in the modified dimensionless height.The interlayer boundary is fixed and defined on the basis of the bifurcation hypothesis.This hypothesis postulates the existence within the ASL of a domain of strong turbulence,represented by a coherent structure formed by an ensemble of small convective eddies(thermals),and a domain of weak turbulence,represented by eddy-wave motion.According to the bifurcation hypothesis,the strong-turbulence domain corresponds to the forcedconvection sublayer,whereas the weak-turbulence domain corresponds to the frictional-heat sublayer.The proposed approach makes it possible to construct a one-parameter family of approximations for a wide class of turbulent moments.The one-parameter model,validated against available experimental data,shows that the proposed piecewiselinear approximation is accurate across the entire convective ASL and demonstrates a high degree of universality.展开更多
The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tu...The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tube(CT)grids(3D-CTGs)using a 3D porous anodic aluminum oxide template-assisted method as electrodes of electrical double-layer capacitors(EDLCs),showing excellent frequency response performance.The unique design warrants fast ion migration channels,excellent electronic conductivity,and good structural stability.This study achieved one of the highest carbon-based ultrahigh-power EDLCs with the 3D-CTG electrodes,resulting in ultrahigh power of 437 and 1708 W·cm−3 with aqueous and organic electrolytes,respectively.Capacitors constructed with these electrodes would have important application prospects in the ultrahigh-power output.The rational design and fabrication of the 3D-CTGs electrodes have demonstrated their capability to build capacitors with ultrahighpower performance and open up new possibilities for applications requiring high-power output.展开更多
Lignocellulose is an ideal precursor for supercapacitor electrodes due to its diverse structures and abundant availability.For supercapacitors,particularly electric double-layer capacitors(EDLCs),pore structure is cri...Lignocellulose is an ideal precursor for supercapacitor electrodes due to its diverse structures and abundant availability.For supercapacitors,particularly electric double-layer capacitors(EDLCs),pore structure is critical.This review summarizes advances in lignocellulose-derived hierarchical porous carbon(LHPC)for supercapacitors,focusing on pore structure and future research directions.We discuss how pore structure influences supercapacitor performance,the activation methods for creating pores in LHPC,and review studies on optimizing pore structure for high-performance supercapacitors.Hierarchical porous carbon should feature a sufficient micropore surface area along with suitable mesoporous and macroporous surfaces to enhance rate performance while maintaining capacitance.This review is expected to actively advance the selection of lignocellulosic precursors and the development of optimized pore structure models,with the ultimate goal of enabling efficient production of lignocellulose-derived hierarchical porous carbon electrodes with superior properties.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074213 and 11574108)the National Key R&D Program of China(Grant No.2022YFA1403103)+2 种基金the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province(Grant No.ZR2023MA082)the Project of Introduction and Cultivation for Young Innovative Talents in Colleges and Universities of Shandong Province。
文摘Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.
基金National Natural Science Foundation of China(41475068,40805034)Special Scientific Research Project for Public Interest(GYHY201206009)Fundamental Research Funds for the Central Universities of China(lzujbky-2014-203)
文摘Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.
文摘In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.
基金National Natural Science Foundation of China(No.61376017)。
文摘Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.
基金the National Natural Science Foundation of China(Nos.52173033,51773044 and 51603047)Guangzhou Science and Technology Plan Project(No.202102020952)+2 种基金Research and Development Plan for Key Areas in Guangdong Province(No.2019B090914002)the Project of Science Foundation of Guangdong Province(No.2021A1515011914)Foshan Science and technology innovation project(No.FS0AA-KJ919-4402-0145).
文摘Due to the mechanical stability of the PP layer,the oriented PP/PE double-layer film with a row-nucleated crystalline structure can be annealed at a higher temperature than the PE monolayer film.In this work,the effects of annealing temperature within the melting range of PE on the crystalline structure and properties of PP/PE double-layer films were studied.When the annealing temperature is between 100 and 130℃,below the melting point of PE,the crystallinity,the long period,lateral dimension and orientation of the lamellae in the PE layer increase with the annealing temperature due to the melting of thin lamellae and the self-nucleated effect of partially-melted melts during annealing.With the annealing temperature further increasing to 138℃,near the melting ending point of PE,since the lamellae melt completely and the melt memory becomes weak during annealing,some spherulite structures are formed in the annealed sample,resulting in a decrease of orientation.In contrast,the annealing only causes the appearance of a low-temperature endothermic plateau in the PP layer.The improved size and orientation of lamellar structure in the PE layer increase the pore arrangement and porosity of the stretched PP/PE microporous membrane.This study successfully applies the self-nucleation effect of partially-melted polymer melt into the practical annealing process,which is helpful to guide the production of high-performance PP/PE/PP lithium batteries separator and the annealing process of other multilayer products.
基金supported by the Aviation Science Foundation,China (Grant No.2009ZF52063)the Research Fund for the Doctoral Program of Higher Education of China (Grant No.20103227110006)the Jiangsu Provincial Postgraduate Cultivation and Innovation Project,China (Grant No.CX10B-257Z)
文摘Microwave absorption properties of the nanocrystalline strontium ferrite （SrFe12O19） and iron （α-Fe） microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz 18 GHz. For the singlelayer absorbers, the nanocrystalline SrFe12O19 microfibers show some microwave absorptions at 6 GHz 18 GHz, with a minimum reflection loss （RL） value of -11.9 dB at 14.1 GHz for a specimen thickness of 3.0 mm, while for the nanocrystalline α-Fe microfibers, their absorptions largely take place at 15 GHz-18 GHz with the RL value exceeding -10 dB, with a minimum .RL value of about -24 dB at 17.5 GHz for a specimen thickness of 0.7 mm. For the doublelayer absorber with an absorbing layer of α-Fe microfibers with a thickness of 0.7 mm and matching layer of SrFe12O19 microfibers with a thickness of 1.3 ram, the minimum RL value is about -63 dB at 16.4 GHz and the absorption band width is about 6.7 GHz ranging from 11.3 GHz to 18 GHz with the RL value exceeding -10 dB which covers the whole Ku-band （12.4 GHz 18 GHz） and 27% of X-band （8.2 GHz 12.4 GHz）.
基金Funded by the Natural Science Foundation of Nanping of China(No.N2021J002)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110304)+3 种基金Guangzhou Science and Technology Plan(No.202102020224)Natural Science Foundation of Fujian Province(No.2020Y0092)Natural Science Foundation of Fujian Province(No.2023J011044)Resource Chemical Industry and Technology Foundation of Nanping(No.N2020Z003)。
文摘To develop the microwave absorbing(MA)properties of cementitious material mixed with mine solid waste,the iron tailings cementitious microwave absorbing materials were prepared.The iron tailings was treated into different particle sizes by planetary ball mill,and the physicochemical properties of iron tailings were tested by laser particle size analyzer and scanning electron microscope(SEM).The electromagnetic parameters of iron tailings cementitious materials were characterized by a vector network analyzer and simulated MA properties,and the MA properties of iron tailings-cement composite system with steel fiber as absorber was studied.Based on the design of the single-layer structure,optimum mix ratio and thickness configuration method of double-layer structure were further studied,meanwhile,the mechanical properties and engineering application were analyzed and discussed.The results show that the particle size of iron tailings can afiect its electromagnetic behavior in cementitious materials,and the smaller particles lead the increase of demagnetisation efiect induced by domain wall motion and achieve better microwave absorbing properties in cementitious materials.When the thickness of matching layer and absorbing layer is 5 mm,the optimized microwave absorbing properties of C1/C3 double-layer cementitious material can obtain optimal RL value of-27.61 dB and efiective absorbing bandwidth of 0.97 GHz,which attributes to the synergistic efiect of impedance matching and attenuation characteristics.The double-layer microwave absorbing materials obtain excellent absorbing properties and show great design flexibility and diversity,which can be used as a suitable candidate for the preparation of favorable microwave absorbing cementitious materials.
基金Fund by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (No.2018YFD1101002-03)。
文摘Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.
基金supported by Hi-Tech Research and Development Program of China (Grant Nos. 2007AA05Z436 and 2009AA050602)Science and Technology Support Project of Tianjin (Grant No. 08ZCKFGX03500)+3 种基金the National Basic Research Program of China (Grant Nos. 2011CB201605 and 2011CB201606)the National Natural Science Foundation of China (Grant No. 60976051)International Cooperation Project between China-Greece Government (Grant No. 2009DFA62580)Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0295)
文摘Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82 × 10^-3 Ω. cm and particle grains. The doublelayers structure is designed to fabricate the ZnO：In thin film with low resistivity （2.58 × 10^-3 Ω. cm） and good surface morphology. It is found that the surface morphology of the double-layer ZnO：In film strongly depends on the substratelayer, and the second-layer plays a large part in the resistivity of the doublewlayer ZnO：In thin film. Both total and direct transmittances of the double-layer ZnO：In film are above 80% in the visible light region. Single junction a-Si：H solar cell based on the double-layer ZnO：In as front electrode is also investigated.
基金This work was supported by the financial support from the Major Special Projects of Technological Innovation in Hubei Province(2019AAA002)the National Key R&D Program of China(2018YFB1105503)Fundamental Research Funds for the Central Universities(2019kfyXMPY020,2020kfyFPZX003,2018KFYYXJJ030,and 2019kfyXKJC011).
文摘Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair.In this work,T-ZnO_(w) enhanced biphasic calcium phosphate(BCP)scaffolds with triply periodic minimal surface(TPMS)-based double-layer porous structure were fabricated by digital light processing(DLP)with high precision.Property of suspension was first discussed to obtain better printing quality.After sintering,T-ZnO_(w) reacts with b-tricalcium phosphate(β-TCP)to form Ca_(19)Zn_(2)(PO_(4))14,and inhibits the phase transition toα-TCP.With the content of T-ZnO_(w) increasing from 0 to 2 wt%,the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress,and have the effect of pulling out as well as fracture toughening.However,excessive whiskers will reduce the cure depth,and cause more printing defects,thus reducing the mechanical strength.Besides,T-ZnO_(w) accelerates the deposition of apatite,and the sample with 2 wt%T-ZnO_(w) shows the fastest mineralization rate.The good biocompatibility has been proved by cell proliferation test.Results confirmed that doping T-ZnO_(w) can improve the mechanical strength of BCP scaffolds,and keep good biological property,which provides a new strategy for better bone repair.
基金supported by the Dalian Shipbuilding Industry Co., Ltd
文摘The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interaction numerical methods including Fluid FEM and Fluid BEM were used in this case. The comparison of numerical and theoretical results by the present method shows that ANSYS/Fluid80 is more credible, the NASTRAN/Virtual Mass Method is more suitable for engineering calculations and results of the same-phase vibration by the present method is more accurate.
基金the National Key Laboratory Open Foundation of Tractor Power System(Grant No.SKT2017012)the National Natural Science Foundation of China(Grant No.51575410).
文摘The micro-perforated panel(MPP)structure has been widely used in various noise control applications,and thus its acoustic performance prediction has been receiving increasing attention.The acoustic performance of simple MPP structures,such as a MPPsound absorber,has been predicted using an analytical calculation method.However,this is not a suitable approach toward predicting the acoustic performance of complicated MPP structures,owing to the structural complexity of these structures.Moreover,the many perforations of submillimeter scale diameter render the MPP structures very difficult to analyze using numerical simulation.Thus,this study focused on two different simplified MPP simulation methods:the transfer admittance method and the equivalent fluid method,and their application on double-layer MPP structures.Based on the two simplified MPP simulation methods,the transmission loss value of the double-layer MPP mufflers with two sets of different structural parameters was calculated,respectively.The predicted results were compared with the impedance tube measurements.The results revealed that the two simplified MPP simulation methods could effectively predict the acoustic performance of doublelayer MPP structures.Moreover,the prediction based on the transfer admittance method can outperform the two simplified simulation methods.
基金supported by the National Natural Science Foundation of China(No.52371075)the National Training Program of Innovation and Entrepreneurship for Undergraduates,the Young Elite Scientists Sponsorship Program by CAST(No.YESS20200083)+1 种基金the Young Talent Fund of the University Association for Science and Technology in Shaanxi,China(No.20190403)the Fundamental Research Funds for the Central Universities(No.xzy012022057).
文摘Double-layered thermal barrier coatings(DL-TBCs)have been developed to meet multiple service requirements,such as low thermal conductivity,high thermal stability,and high fracture toughness.Conventional DL-TBCs are often designed on the basis of equal total thickness to have long lifespans,which may weaken the thermal insulation.The reason is that the single-scale designed structure often has opposite effects on the thermal and mechanical properties.To enhance both the thermal insulation and lifespan,this work designed durable DL-TBCs at multiple scales under equivalent thermal insulation.The macroscopic thickness ratio of the top layer to the bottom layer was tailored to optimize the total and single thicknesses,and the microscopic pore size in the top layer was tailored to resist sintering.Six groups of samples with different thickness ratios were prepared.The thermal cycling test revealed that the lifespan of DL-TBCs first increases but then decreases with increasing thickness ratio.The optimized thickness ratio is 2:3 for DL-TBCs,which have the largest lifespan among the six groups.The cross-sectional morphologies revealed that the failure mode changed from the spallation of the top layer to the delamination of the total double layers.The long lifespan of the optimized DL-TBCs stems from the cotailored thickness ratio and porous structure in the top layer to lower the total cracking driving force.
基金carried out by Vulfson A.N.within the framework of the Governmental Order to the Water Problems Institute,Russian Academy of Sciences,research project No.FMWZ-2022-0001。
文摘A modification of the Monin-Obukhov theory is proposed,introducing a two-layer model of the convective atmospheric surface layer(ASL)with a fixed interlayer boundary.The convective ASL is assumed to consist of a frictional-heat sublayer,adjacent to the underlying surface,and a forced-convection sublayer.Approximations of the turbulent moments are derived independently for each sublayer in the form of truncated Taylor expansions in the modified dimensionless height.The interlayer boundary is fixed and defined on the basis of the bifurcation hypothesis.This hypothesis postulates the existence within the ASL of a domain of strong turbulence,represented by a coherent structure formed by an ensemble of small convective eddies(thermals),and a domain of weak turbulence,represented by eddy-wave motion.According to the bifurcation hypothesis,the strong-turbulence domain corresponds to the forcedconvection sublayer,whereas the weak-turbulence domain corresponds to the frictional-heat sublayer.The proposed approach makes it possible to construct a one-parameter family of approximations for a wide class of turbulent moments.The one-parameter model,validated against available experimental data,shows that the proposed piecewiselinear approximation is accurate across the entire convective ASL and demonstrates a high degree of universality.
基金supported by the National Natural Science Foundation of China(Nos.91963202,52072372,and 52232007).
文摘The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tube(CT)grids(3D-CTGs)using a 3D porous anodic aluminum oxide template-assisted method as electrodes of electrical double-layer capacitors(EDLCs),showing excellent frequency response performance.The unique design warrants fast ion migration channels,excellent electronic conductivity,and good structural stability.This study achieved one of the highest carbon-based ultrahigh-power EDLCs with the 3D-CTG electrodes,resulting in ultrahigh power of 437 and 1708 W·cm−3 with aqueous and organic electrolytes,respectively.Capacitors constructed with these electrodes would have important application prospects in the ultrahigh-power output.The rational design and fabrication of the 3D-CTGs electrodes have demonstrated their capability to build capacitors with ultrahighpower performance and open up new possibilities for applications requiring high-power output.
基金financial support for this research from the National Key Research Development Program of China(No.2021YFB3800300)Shanghai Pujiang Programme(No.23PJD045)the Shanghai Science and Technology Committee(No.24CL2900600).
文摘Lignocellulose is an ideal precursor for supercapacitor electrodes due to its diverse structures and abundant availability.For supercapacitors,particularly electric double-layer capacitors(EDLCs),pore structure is critical.This review summarizes advances in lignocellulose-derived hierarchical porous carbon(LHPC)for supercapacitors,focusing on pore structure and future research directions.We discuss how pore structure influences supercapacitor performance,the activation methods for creating pores in LHPC,and review studies on optimizing pore structure for high-performance supercapacitors.Hierarchical porous carbon should feature a sufficient micropore surface area along with suitable mesoporous and macroporous surfaces to enhance rate performance while maintaining capacitance.This review is expected to actively advance the selection of lignocellulosic precursors and the development of optimized pore structure models,with the ultimate goal of enabling efficient production of lignocellulose-derived hierarchical porous carbon electrodes with superior properties.
