The addition of 2,5-pyridinedicarboxylic acid(2,5-PDCA)to the Mg-Al LDH coating,which was prepared by one-step hydrothermal synthesis,had extremely enhanced the corrosion protection of AZ31 Mg alloy,although the 2,5-P...The addition of 2,5-pyridinedicarboxylic acid(2,5-PDCA)to the Mg-Al LDH coating,which was prepared by one-step hydrothermal synthesis,had extremely enhanced the corrosion protection of AZ31 Mg alloy,although the 2,5-PDCA could not be intercalated into the interlayer spacing.The corrosion current density of 0.05 mol L^(−1)2,5-PDCA LDH containing LDH coating is 3.18 nA cm^(−2),reduced by two orders of magnitude compared to the LDH coating without inhibitor,and the corrosion inhibition efficiency of the coating is 98.05%.The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers.The innermost layer is a thick layer that consists of Mg(OH)_(2)and the intermediate layer is LDH,which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg.This kind of sediment/LDH/Mg(OH)_(2)three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy.展开更多
This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double...This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.展开更多
Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model ar...Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model are established. The ablation program was written and the experimental data of 70 lb BATES engine platform was used for model validation. The relative errors between the simulation calculation results and the experimental results were −6.83% - 10.20%. The ablation program was applied to study the effects of combustion chamber temperature, pressure, oxidation component concentration, throat particle concentration and particle scouring angle on the nozzle throat liner, which provides a reference for the design of the nozzle throat liner and the estimation of solid rocket motor ablation.展开更多
Short-term traffic flow is one of the core technologies to realize traffic flow guidance. In this article, in view of the characteristics that the traffic flow changes repeatedly, a short-term traffic flow forecasting...Short-term traffic flow is one of the core technologies to realize traffic flow guidance. In this article, in view of the characteristics that the traffic flow changes repeatedly, a short-term traffic flow forecasting method based on a three-layer K-nearest neighbor non-parametric regression algorithm is proposed. Specifically, two screening layers based on shape similarity were introduced in K-nearest neighbor non-parametric regression method, and the forecasting results were output using the weighted averaging on the reciprocal values of the shape similarity distances and the most-similar-point distance adjustment method. According to the experimental results, the proposed algorithm has improved the predictive ability of the traditional K-nearest neighbor non-parametric regression method, and greatly enhanced the accuracy and real-time performance of short-term traffic flow forecasting.展开更多
In this study,the effects of three different particle sizes of wood wastes(A=–8+12 mesh;B=–12+20 mesh;C=–20+30 mesh)and factory shavings(D)on the properties of particleboard were investigated.According to the test ...In this study,the effects of three different particle sizes of wood wastes(A=–8+12 mesh;B=–12+20 mesh;C=–20+30 mesh)and factory shavings(D)on the properties of particleboard were investigated.According to the test results,three-layer particleboard was designed.Particleboard face layers made with mixture of A,B,and C.The core layer made with D.The ratio of core layer to face layers is 50:50.Three-layer particleboard were fabricated with 12%urea-formaldehyde(UF)resins and three different high voltage electrostatic field intensities(0 kv,30 kv,60 kv).The internal bond(IB)strength,modulus of rupture(MOR),modulus of elasticity(MOE),thickness swelling(TS),and water absorption(WA)of particleboard were evaluated.The density distribution of the three-layer particleboard were examined by vertical density profiles(VDP),and the bonding mechanism and functional groups changes in the particles were analyzed by FTIR analysis.The results showed that HVEF treatment intensity play a remarkable role in properties of particleboard.The particleboard with higher electrostatic field intensities treatment has higher MOE,MOR,IB,and TS.Under HVEF treatment(60 kv),the MOR,modulus of MOE,and IB of three-layer particleboard were 23.61 N/mm^(2),2787.09 N/mm^(2),and 0.86 N/mm^(2),respectively.FTIR indicated that the surface activity of wood particles was increased electric field treatment.展开更多
Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environmen...Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environment to the inhibitor have always been the important issues.This study focuses on the preparation,characterization and anti-migration behavior of graphene oxide(GO)/HTPB nanocomposite liner.The GO/HTPB(GH)composite liners affect the migration of small molecules through a tighter cross-linked structure and weakening function of small molecule adsorption.The anti-migration performance of the liner at different temperatures was analyzed,and the influence of the added amount of GO on the anti-migration performance and adhesion performance was also systematically studied.The overall performance of the liner is optimized when the amount of GO filler is 0.3 wt%.After adding 0.3 wt%GO,the concentration of dioctyl sebacate(DOS)migrated into the liner is decreased by 23.28%,and the concentration of water molecules is decreased by 51.89%,indicating that the introduction of GO can significantly improve the anti-migration performance of the liner.In addition,the bond strength is greatly increased from 0.25 MPa to 0.95 MPa,which meets the application requirements of the current propellant system.This research provides an important way for the preparation of structure-function synergistic anti-migration composite liners.展开更多
The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the...The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments. A kind of simple structure, small size, good stability, high sensitivity chemical concentration sensor is obtained.展开更多
In this work,trapped mode frequencies are computed for a submerged horizontal circular cylinder with the hydrodynamic set-up involving an infinite depth three-layer incompressible fluid with layer-wise different densi...In this work,trapped mode frequencies are computed for a submerged horizontal circular cylinder with the hydrodynamic set-up involving an infinite depth three-layer incompressible fluid with layer-wise different densities.The impermeable cylinder is fully immersed in either the bottom layer or the upper layer.The effect of surface tension at the surface of separation is neglected.In this set-up,there exist three wave numbers:the lowest one on the free surface and the other two on the internal interfaces.For each wave number,there exist two modes for which trapped waves exist.The existence of these trapped modes is shown by numerical evidence.We investigate the variation of these trapped modes subject to change in the depth of the middle layer as well as the submergence depth.We show numerically that two-layer and single-layer results cannot be recovered in the double and single limiting cases of the density ratios tending to unity.The existence of trapped modes shows that in general,a radiation condition for the waves at infinity is insufficient for the uniqueness of the solution of the scattering problem.展开更多
The quantum fluctuations of a three-layer Heisenberg model with six sublattices are studied by the retarded Green's function method and the spin-wave theory. The effects of anisotropy on the quantum fluctuations at z...The quantum fluctuations of a three-layer Heisenberg model with six sublattices are studied by the retarded Green's function method and the spin-wave theory. The effects of anisotropy on the quantum fluctuations at zero temperature are discussed. The results show that the interlayer anisotropy plays an important role in balancing the quantum competitions.展开更多
A three-layer model of the thermohaline structure is developed on the basis of the two -layer model of thermocline. The model is able to simulate the depth,thickness and intensity of both thermocline and halocline, an...A three-layer model of the thermohaline structure is developed on the basis of the two -layer model of thermocline. The model is able to simulate the depth,thickness and intensity of both thermocline and halocline, and the temperature and salinity of both upper layer and lower layer in the shallow seas.Camparison of simulation with data is favorable.Detailed analysis is made on a variety of factors affecting the intensity of the thermocline.展开更多
Once more to the lake is a representative work of the American Writer, Elwyn Brooks White, and has been acclaimed by people in the world. The paper offers a three-layered contrasting analysis of the essay. By detailed...Once more to the lake is a representative work of the American Writer, Elwyn Brooks White, and has been acclaimed by people in the world. The paper offers a three-layered contrasting analysis of the essay. By detailed analysis of the contrasts running through the whole essay, the author finds that those contrasts are symbol of White's internal struggle and reflection for life.On the foundation of the three-layered contrasts, the paper presents the theme analysis and clarifies the content of the essay.展开更多
Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave s...Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interracial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.展开更多
Purpose: Comparison of transcutaneous immunization of ovalbumin (OA) between two-and three-layered dissolving microneedles (MN) in rats. Methods: We prepared 500 μm long two-layered and three-layered dissolving micro...Purpose: Comparison of transcutaneous immunization of ovalbumin (OA) between two-and three-layered dissolving microneedles (MN) in rats. Methods: We prepared 500 μm long two-layered and three-layered dissolving microneedle (2-MN and 3-MN, respectively) arrays from chondroitin sulfate as the base, and OA as the model antigen. The 2-MN containing OA at the acral portion and 3-MN with OA at the second portion were administered to rat skin transcutaneously. As a positive control, OA solution was injected subcutaneously (sc). The OA delivery and diffusion in the rat skin were studied using confocal microscopy with fluorescein-conjugated OA (FL-OA). Results: The formulated positions of OA were 0-155 ± 5 μm for 2-MN and 175 ± 4 – 225 ± 5 μm for 3-MN. The administered doses of OA were 2.2 ± 0.1 μg, 12.0 ± 0.2 μg and 22.0 ± 0.2 μg for 2-MN, 1.8 ± 0.2 μg, 12.6 ± 0.7 μg, and 20.4 ± 0.3 μg for 3-MN, 10 μg, 100 μg and 1000 μg for sc injection. At 4 weeks after the first administration, 3-MN showed about 2.5-7.0 fold and 5.4 fold higher total Ig (G + A + M) antibody than 2-MN and sc injection of the OA solution. Conclusions: The 3-MN, which delivered OA to the epidermis, is a useful drug delivery system for transcutaneous antigen delivery.展开更多
A one-dimentional three-layer model for the thermal structure in the Huanghai Sea is presented in this study, me model consists of the upper mixed layer caused by heating and wind mixing, the lower mixed layer driven ...A one-dimentional three-layer model for the thermal structure in the Huanghai Sea is presented in this study, me model consists of the upper mixed layer caused by heating and wind mixing, the lower mixed layer driven by tidal mixing, and the thermocline with certain thickness. The entrainment velocities of the upper and lower layers are obtained respectively. The results show that the model is capable of describing the development and decline processes of the seasonal thermocline in the Huanghai Sea, simulating successfully the Huanghai Sea Cold Water Mass, the nearshore front and surface cold water off North Jiangsu and explaining reasonably their formation mechanisms as well as the strong thermocline off Qingdao. It is suggested that the tidal mixing plays key role in the formation of the nearshore front off North Jiangsu and the strong thermocline off Qingdao. The wind mixing and the tidal mixing make the lower layer water with high nutrients go up to the upper layer. This physical process may be significant for biological plant production.展开更多
In the present study, vibration analysis of a three-layered cylindrical shell is performed whose inner and outer layers are composed of functionally graded materials whereas the middle one is assumed to be of isotropi...In the present study, vibration analysis of a three-layered cylindrical shell is performed whose inner and outer layers are composed of functionally graded materials whereas the middle one is assumed to be of isotropic material. This formation of a cylindrical shell influences stiffness modulii and the resultant material properties. The shell problem is formulated from the constitutive relations of stresses and strains with the displacement deformations and they are taken from Love’s thin shell theory. This problem is transformed into the integral form by evaluating the expressions for the strain and kinetic energies of the shell. Rayleigh-Ritz method is employed to solve the shell dynamic equations. Vibration characteristics of these cylindrical shells are investigated for a number of physical parameters and configurations of the fabrication of shells. The axial modal dependence is approximated by the characteristic beam functions that satisfy the boundary conditions. Results evaluated, show good agreement with the open literature.展开更多
Dense pre-hydrated geosynthetic clay liners(DPH GCLs)were manufactured as innovative materials accompanied by the advantage of lower hydraulic conductivity(k).The k of DPH GCLs permeated with de-ionized water(DIW)was ...Dense pre-hydrated geosynthetic clay liners(DPH GCLs)were manufactured as innovative materials accompanied by the advantage of lower hydraulic conductivity(k).The k of DPH GCLs permeated with de-ionized water(DIW)was 9.8×10^(−12) m/s.The effect of Cu^(2+)synthetic solution on DPH GCLs was discussed.Furthermore,the effect mechanism was studied on the basis of test technologies.A significant adverse impact on hydraulic performance of DPH GCLs is found when the concentration of Cu^(2+)is greater than 1 g/L.SEM,XRD,XRF,FTIR,and XPS analyses show that the effect of Cu^(2+)on DPH GCLs includes two steps.Firstly,Cu^(2+)interacts with hydrophobic organic matter(HOM),and the adhesion of bentonite is destroyed,and some holes appear.The Cu^(2+)contacts with bentonite directly,and Cu^(2+)interacts with bentonite through ion exchange.Passivated phenomenon occurs on the surface of the bentonite,and swelling ability of bentonite is reduced,which causes permeable DPH GCLs.展开更多
Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study,...Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study, a multi-section method was proposed to design the spin-compensation liner. The spincompensation rate(SCR) of the liner was defined as the specific angular velocity that a fluted liner can offset. Based on the plain stress theory, SPH numerical method was applied to study the converging process of the 2D fluted structure. The spin-compensation mechanism of the fluted structure was illustrated. Then, nine cross sections were chosen along the liner axis equidistantly. On each of the section, a 2D fluted structure was designed to offset a given initial angular velocity. After, the optimized fluted structures were integrated into a 3D fluted liner. Jet appearances of the normal liner and the fluted liners under different initial angular velocities were compared, which verifies the practicality of the multi-sectional method. The multi-section optimization method provides a new efficient method of designing the shaped charge liner for a specific usage.展开更多
This study proposed an analytical model for the tunnel supported with a tangentially yielding liner in viscoelastic ground.The efficiency of the developed analytical model was verified by comparing the calculated resu...This study proposed an analytical model for the tunnel supported with a tangentially yielding liner in viscoelastic ground.The efficiency of the developed analytical model was verified by comparing the calculated results with associated numerical simulation results.Using the analytical model,a comprehensive parameter sensitivity analysis was performed to examine the effects of the rate of tunnel face advancement,concrete liner thickness,installation time of liner,and strength and thickness of yielding elements on the tunnel responses.The results highlight the significant benefit of the tangentially yielding liner to relieve overstress in the tunnel liner and improve the stability of the tunnel.The yield efficiency of the tangentially yielding liner depends highly on the yielding strength and deformable capacity of the yielding elements and less on the installation time.展开更多
With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic ...With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic development.This paper proposed a novel eco-friendly sound absorbing structure(NSAS)liner for noise reduction in elevator shafts.The base layer integrated with the shaft walls is a damping gypsum mortarboard,and a rock wool board and a perforated cement mortarboard are used to compose the NSAS.Based on the acoustic impedance theory of porous materials and perforated panels,the sound absorption theory of the NSAS was proposed;the parameter effects of the rock wool board(flow resistivity,porosity,structure factor)and perforated panel(perforated rates,thickness,density,perforated diameter)on NSAS absorption were discussed theoretically for absorption improvement,and experiments were also conducted.Numerical results showed that the perforation rate,the thickness of the perforated plate,and the porosity,flow resistance,and volume density of the rock wool board played a key issue in the absorption performances of the NSAS.Experiments verified the accuracy of the proposed theoretical model.Wideband sound absorption performance of the NSAS at frequencies between 500–1600 Hz was achieved in both numerical analysis and experiments,and the sound absorption coefficient was improved to 0.72 around 1000 Hz after parameter adjustments.The NSAS proposed in this paper can also be made of other renewable materials with preferable structure strength and still has the potential to broaden the absorption bandwidth.It can provide a reference for controlling the elevator shaft noise.展开更多
文摘The addition of 2,5-pyridinedicarboxylic acid(2,5-PDCA)to the Mg-Al LDH coating,which was prepared by one-step hydrothermal synthesis,had extremely enhanced the corrosion protection of AZ31 Mg alloy,although the 2,5-PDCA could not be intercalated into the interlayer spacing.The corrosion current density of 0.05 mol L^(−1)2,5-PDCA LDH containing LDH coating is 3.18 nA cm^(−2),reduced by two orders of magnitude compared to the LDH coating without inhibitor,and the corrosion inhibition efficiency of the coating is 98.05%.The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers.The innermost layer is a thick layer that consists of Mg(OH)_(2)and the intermediate layer is LDH,which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg.This kind of sediment/LDH/Mg(OH)_(2)three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy.
基金funded by the China Postdoctoral Science Foundation(Grant No.2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(Grant No.KFJJ23-07M)。
文摘This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.
文摘Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model are established. The ablation program was written and the experimental data of 70 lb BATES engine platform was used for model validation. The relative errors between the simulation calculation results and the experimental results were −6.83% - 10.20%. The ablation program was applied to study the effects of combustion chamber temperature, pressure, oxidation component concentration, throat particle concentration and particle scouring angle on the nozzle throat liner, which provides a reference for the design of the nozzle throat liner and the estimation of solid rocket motor ablation.
文摘Short-term traffic flow is one of the core technologies to realize traffic flow guidance. In this article, in view of the characteristics that the traffic flow changes repeatedly, a short-term traffic flow forecasting method based on a three-layer K-nearest neighbor non-parametric regression algorithm is proposed. Specifically, two screening layers based on shape similarity were introduced in K-nearest neighbor non-parametric regression method, and the forecasting results were output using the weighted averaging on the reciprocal values of the shape similarity distances and the most-similar-point distance adjustment method. According to the experimental results, the proposed algorithm has improved the predictive ability of the traditional K-nearest neighbor non-parametric regression method, and greatly enhanced the accuracy and real-time performance of short-term traffic flow forecasting.
基金The Authors acknowledge funding support by the National Key R&D Program of China(2017YFC0703501)The authors wish to acknowledge the National Natural Science Foundation of China(Grant No.32071700).
文摘In this study,the effects of three different particle sizes of wood wastes(A=–8+12 mesh;B=–12+20 mesh;C=–20+30 mesh)and factory shavings(D)on the properties of particleboard were investigated.According to the test results,three-layer particleboard was designed.Particleboard face layers made with mixture of A,B,and C.The core layer made with D.The ratio of core layer to face layers is 50:50.Three-layer particleboard were fabricated with 12%urea-formaldehyde(UF)resins and three different high voltage electrostatic field intensities(0 kv,30 kv,60 kv).The internal bond(IB)strength,modulus of rupture(MOR),modulus of elasticity(MOE),thickness swelling(TS),and water absorption(WA)of particleboard were evaluated.The density distribution of the three-layer particleboard were examined by vertical density profiles(VDP),and the bonding mechanism and functional groups changes in the particles were analyzed by FTIR analysis.The results showed that HVEF treatment intensity play a remarkable role in properties of particleboard.The particleboard with higher electrostatic field intensities treatment has higher MOE,MOR,IB,and TS.Under HVEF treatment(60 kv),the MOR,modulus of MOE,and IB of three-layer particleboard were 23.61 N/mm^(2),2787.09 N/mm^(2),and 0.86 N/mm^(2),respectively.FTIR indicated that the surface activity of wood particles was increased electric field treatment.
基金the financial support of the National Natural Science Foundation of China(grant number 22005145)the Natural Science Foundation of Jiangsu Province(grant number BK20180495,BK20180698)+1 种基金the Opening Project of Key Laboratory of Special Energy Materials(Nanjing University of Science and Technology)the Fundamental Research Funds for the Priority Academic Program Development of Jiangsu Higher Education Institutions(grant number 30919011404)。
文摘Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environment to the inhibitor have always been the important issues.This study focuses on the preparation,characterization and anti-migration behavior of graphene oxide(GO)/HTPB nanocomposite liner.The GO/HTPB(GH)composite liners affect the migration of small molecules through a tighter cross-linked structure and weakening function of small molecule adsorption.The anti-migration performance of the liner at different temperatures was analyzed,and the influence of the added amount of GO on the anti-migration performance and adhesion performance was also systematically studied.The overall performance of the liner is optimized when the amount of GO filler is 0.3 wt%.After adding 0.3 wt%GO,the concentration of dioctyl sebacate(DOS)migrated into the liner is decreased by 23.28%,and the concentration of water molecules is decreased by 51.89%,indicating that the introduction of GO can significantly improve the anti-migration performance of the liner.In addition,the bond strength is greatly increased from 0.25 MPa to 0.95 MPa,which meets the application requirements of the current propellant system.This research provides an important way for the preparation of structure-function synergistic anti-migration composite liners.
文摘The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments. A kind of simple structure, small size, good stability, high sensitivity chemical concentration sensor is obtained.
文摘In this work,trapped mode frequencies are computed for a submerged horizontal circular cylinder with the hydrodynamic set-up involving an infinite depth three-layer incompressible fluid with layer-wise different densities.The impermeable cylinder is fully immersed in either the bottom layer or the upper layer.The effect of surface tension at the surface of separation is neglected.In this set-up,there exist three wave numbers:the lowest one on the free surface and the other two on the internal interfaces.For each wave number,there exist two modes for which trapped waves exist.The existence of these trapped modes is shown by numerical evidence.We investigate the variation of these trapped modes subject to change in the depth of the middle layer as well as the submergence depth.We show numerically that two-layer and single-layer results cannot be recovered in the double and single limiting cases of the density ratios tending to unity.The existence of trapped modes shows that in general,a radiation condition for the waves at infinity is insufficient for the uniqueness of the solution of the scattering problem.
基金Project supported by the Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University,China(Grant No.LZUMMM2010010)the Scientific Foundation of the Educational Department of Liaoning Province,China(Grant No.L2010390)+2 种基金the Natural Science Foundation of Liaoning Province of China(Grant No.20102171)the Scientific Technology Plan of Shenyang,China(Grant No.F10-205-1-33)the Excellent Talents Program of the University of Liaoning Province,China(Grant No.LR201031)
文摘The quantum fluctuations of a three-layer Heisenberg model with six sublattices are studied by the retarded Green's function method and the spin-wave theory. The effects of anisotropy on the quantum fluctuations at zero temperature are discussed. The results show that the interlayer anisotropy plays an important role in balancing the quantum competitions.
文摘A three-layer model of the thermohaline structure is developed on the basis of the two -layer model of thermocline. The model is able to simulate the depth,thickness and intensity of both thermocline and halocline, and the temperature and salinity of both upper layer and lower layer in the shallow seas.Camparison of simulation with data is favorable.Detailed analysis is made on a variety of factors affecting the intensity of the thermocline.
文摘Once more to the lake is a representative work of the American Writer, Elwyn Brooks White, and has been acclaimed by people in the world. The paper offers a three-layered contrasting analysis of the essay. By detailed analysis of the contrasts running through the whole essay, the author finds that those contrasts are symbol of White's internal struggle and reflection for life.On the foundation of the three-layered contrasts, the paper presents the theme analysis and clarifies the content of the essay.
基金supported by the Natural Science Foundation of Inner Mongolia,China(Grant No 200711020116)Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences(Grant No KLOCAW0805)+1 种基金the Key Program of the Scientific Research Plan of Inner Mongolia University of Technology,China(Grant No ZD200608)National Science Fund for Distinguished Young Scholars of China(Grant No 40425015)
文摘Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interracial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.
文摘Purpose: Comparison of transcutaneous immunization of ovalbumin (OA) between two-and three-layered dissolving microneedles (MN) in rats. Methods: We prepared 500 μm long two-layered and three-layered dissolving microneedle (2-MN and 3-MN, respectively) arrays from chondroitin sulfate as the base, and OA as the model antigen. The 2-MN containing OA at the acral portion and 3-MN with OA at the second portion were administered to rat skin transcutaneously. As a positive control, OA solution was injected subcutaneously (sc). The OA delivery and diffusion in the rat skin were studied using confocal microscopy with fluorescein-conjugated OA (FL-OA). Results: The formulated positions of OA were 0-155 ± 5 μm for 2-MN and 175 ± 4 – 225 ± 5 μm for 3-MN. The administered doses of OA were 2.2 ± 0.1 μg, 12.0 ± 0.2 μg and 22.0 ± 0.2 μg for 2-MN, 1.8 ± 0.2 μg, 12.6 ± 0.7 μg, and 20.4 ± 0.3 μg for 3-MN, 10 μg, 100 μg and 1000 μg for sc injection. At 4 weeks after the first administration, 3-MN showed about 2.5-7.0 fold and 5.4 fold higher total Ig (G + A + M) antibody than 2-MN and sc injection of the OA solution. Conclusions: The 3-MN, which delivered OA to the epidermis, is a useful drug delivery system for transcutaneous antigen delivery.
文摘A one-dimentional three-layer model for the thermal structure in the Huanghai Sea is presented in this study, me model consists of the upper mixed layer caused by heating and wind mixing, the lower mixed layer driven by tidal mixing, and the thermocline with certain thickness. The entrainment velocities of the upper and lower layers are obtained respectively. The results show that the model is capable of describing the development and decline processes of the seasonal thermocline in the Huanghai Sea, simulating successfully the Huanghai Sea Cold Water Mass, the nearshore front and surface cold water off North Jiangsu and explaining reasonably their formation mechanisms as well as the strong thermocline off Qingdao. It is suggested that the tidal mixing plays key role in the formation of the nearshore front off North Jiangsu and the strong thermocline off Qingdao. The wind mixing and the tidal mixing make the lower layer water with high nutrients go up to the upper layer. This physical process may be significant for biological plant production.
文摘In the present study, vibration analysis of a three-layered cylindrical shell is performed whose inner and outer layers are composed of functionally graded materials whereas the middle one is assumed to be of isotropic material. This formation of a cylindrical shell influences stiffness modulii and the resultant material properties. The shell problem is formulated from the constitutive relations of stresses and strains with the displacement deformations and they are taken from Love’s thin shell theory. This problem is transformed into the integral form by evaluating the expressions for the strain and kinetic energies of the shell. Rayleigh-Ritz method is employed to solve the shell dynamic equations. Vibration characteristics of these cylindrical shells are investigated for a number of physical parameters and configurations of the fabrication of shells. The axial modal dependence is approximated by the characteristic beam functions that satisfy the boundary conditions. Results evaluated, show good agreement with the open literature.
基金National Key Research and Development Project of China(No.2017FB0310902)。
文摘Dense pre-hydrated geosynthetic clay liners(DPH GCLs)were manufactured as innovative materials accompanied by the advantage of lower hydraulic conductivity(k).The k of DPH GCLs permeated with de-ionized water(DIW)was 9.8×10^(−12) m/s.The effect of Cu^(2+)synthetic solution on DPH GCLs was discussed.Furthermore,the effect mechanism was studied on the basis of test technologies.A significant adverse impact on hydraulic performance of DPH GCLs is found when the concentration of Cu^(2+)is greater than 1 g/L.SEM,XRD,XRF,FTIR,and XPS analyses show that the effect of Cu^(2+)on DPH GCLs includes two steps.Firstly,Cu^(2+)interacts with hydrophobic organic matter(HOM),and the adhesion of bentonite is destroyed,and some holes appear.The Cu^(2+)contacts with bentonite directly,and Cu^(2+)interacts with bentonite through ion exchange.Passivated phenomenon occurs on the surface of the bentonite,and swelling ability of bentonite is reduced,which causes permeable DPH GCLs.
基金supported by the project of National Natural Science Foundation of China (NSFC, Grant No. 12032006)。
文摘Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study, a multi-section method was proposed to design the spin-compensation liner. The spincompensation rate(SCR) of the liner was defined as the specific angular velocity that a fluted liner can offset. Based on the plain stress theory, SPH numerical method was applied to study the converging process of the 2D fluted structure. The spin-compensation mechanism of the fluted structure was illustrated. Then, nine cross sections were chosen along the liner axis equidistantly. On each of the section, a 2D fluted structure was designed to offset a given initial angular velocity. After, the optimized fluted structures were integrated into a 3D fluted liner. Jet appearances of the normal liner and the fluted liners under different initial angular velocities were compared, which verifies the practicality of the multi-sectional method. The multi-section optimization method provides a new efficient method of designing the shaped charge liner for a specific usage.
基金We acknowledge the funding support from the University Transportation Center for Underground Transportation Infrastructure(UTC-UTI)at the Colorado School of Mines and the U.S.Department of Transportation(DOT)(Grant No.69A3551747118).
文摘This study proposed an analytical model for the tunnel supported with a tangentially yielding liner in viscoelastic ground.The efficiency of the developed analytical model was verified by comparing the calculated results with associated numerical simulation results.Using the analytical model,a comprehensive parameter sensitivity analysis was performed to examine the effects of the rate of tunnel face advancement,concrete liner thickness,installation time of liner,and strength and thickness of yielding elements on the tunnel responses.The results highlight the significant benefit of the tangentially yielding liner to relieve overstress in the tunnel liner and improve the stability of the tunnel.The yield efficiency of the tangentially yielding liner depends highly on the yielding strength and deformable capacity of the yielding elements and less on the installation time.
基金supported by Opening Foundation of Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,China(LNTCCMA-20210104)This work was also supported by the Natural Science Foundation of China(Grant No.51408113)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140632).
文摘With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic development.This paper proposed a novel eco-friendly sound absorbing structure(NSAS)liner for noise reduction in elevator shafts.The base layer integrated with the shaft walls is a damping gypsum mortarboard,and a rock wool board and a perforated cement mortarboard are used to compose the NSAS.Based on the acoustic impedance theory of porous materials and perforated panels,the sound absorption theory of the NSAS was proposed;the parameter effects of the rock wool board(flow resistivity,porosity,structure factor)and perforated panel(perforated rates,thickness,density,perforated diameter)on NSAS absorption were discussed theoretically for absorption improvement,and experiments were also conducted.Numerical results showed that the perforation rate,the thickness of the perforated plate,and the porosity,flow resistance,and volume density of the rock wool board played a key issue in the absorption performances of the NSAS.Experiments verified the accuracy of the proposed theoretical model.Wideband sound absorption performance of the NSAS at frequencies between 500–1600 Hz was achieved in both numerical analysis and experiments,and the sound absorption coefficient was improved to 0.72 around 1000 Hz after parameter adjustments.The NSAS proposed in this paper can also be made of other renewable materials with preferable structure strength and still has the potential to broaden the absorption bandwidth.It can provide a reference for controlling the elevator shaft noise.