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
Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress te...Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress tensor by measuring strain using an HI strain cell.However,existing analytical solutions for stress calculation based on an HI strain cell in a double-layer medium are not applicable when an HI strain cell is used in a three-layer medium,leading to erroneous stress calculations.To address this issue,this paper presents a method for calculating stress tensors in a three-layer medium using numerical simulations,specifically by obtaining a constitutive matrix that relates strain measurements to stress tensors in a three-layer medium.Furthermore,using Latin hypercube sampling (LHS) and orthogonal experimental design strategies,764 groups of numerical models encompassing various stress measurement scenarios have been established and calculated using FLAC^(3D)software.Finally,a surrogate model based on artificial neural network (ANN) was developed to predict constitutive matrices,achieving a goodness of fit (R^(2)) of 0.999 and a mean squared error (MSE) of 1.254.A software program has been developed from this surrogate model for ease of use in practical engineering applications.The method’s accuracy was verified through numerical simulations,analytical solution and laboratory experiment,demonstrating its effectiveness in calculating stress in a three-layer medium.The surrogate model was applied to calculate mining-induced stress in the roadway roof rock of a coal mine,a typical case for stress measurement in a three-layer medium.Errors in stress calculations arising from the use of existing analytical solutions were corrected.The study also highlights the significant errors associated with using double-layer analytical solutions in a three-layer medium,which could lead to inappropriate engineering design.展开更多
This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This researc...This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This research examines the flow of a three-layered viscous fluid,considering the combined influence of heat and solutal buoyancy driven Rayleigh-Bénard convection,as well as thermal and solutal Marangoni convection.The homotopy perturbation method is used to examine and simulate complex fluid flow and transport phenomena,providing important understanding of the fundamental physics and assisting in the optimization of various battery configurations.The inquiry examines the primary elements that influence Marangoni convection and its impact on battery performance,providing insights on possible enhancements in energy storage devices.The findings indicate that the velocity profiles shown graphically exhibit a prominent core zone characterized by the maximum speed,which progressively decreases as it approaches the walls of the channel.This study enhances our comprehension of fluid dynamics and the transmission of heat and mass in intricate systems,which has substantial ramifications for the advancement of sustainable energy solutions.展开更多
This paper raises, for the first time, with a model reading passage, a three-layer passage reading method （3LPRM in brief ） in English reading： reading beyond paragraphs; reading within paragraphs and sentences, an...This paper raises, for the first time, with a model reading passage, a three-layer passage reading method （3LPRM in brief ） in English reading： reading beyond paragraphs; reading within paragraphs and sentences, and reading with coherences of words and expressions. The paper illustrates the definition, contents, characteristics and application of the method which is easy to master and apply. The paper aims at supplying readers especially beginners of E/S/FL （English as second/foreign language） with a practical passage reading method so as to improve their reading efficiency. The paper has some practical significance and directing value.展开更多
Information plays a crucial role in guiding behavioral decisions during public health emergencies. Individuals communicate to acquire relevant knowledge about an epidemic, which influences their decisions to adopt pro...Information plays a crucial role in guiding behavioral decisions during public health emergencies. Individuals communicate to acquire relevant knowledge about an epidemic, which influences their decisions to adopt protective measures.However, whether to disseminate specific information is also a behavioral decision. In light of this understanding, we develop a coupled information–vaccination–epidemic model to depict these co-evolutionary dynamics in a three-layer network. Negative information dissemination and vaccination are treated as separate decision-making processes. We then examine the combined effects of herd and risk motives on information dissemination and vaccination decisions through the lens of game theory. The microscopic Markov chain approach(MMCA) is used to describe the dynamic process and to derive the epidemic threshold. Simulation results indicate that increasing the cost of negative information dissemination and providing timely clarification can effectively control the epidemic. Furthermore, a phenomenon of diminishing marginal utility is observed as the cost of dissemination increases, suggesting that authorities do not need to overinvest in suppressing negative information. Conversely, reducing the cost of vaccination and increasing vaccine efficacy emerge as more effective strategies for outbreak control. In addition, we find that the scale of the epidemic is greater when the herd motive dominates behavioral decision-making. In conclusion, this study provides a new perspective for understanding the complexity of epidemic spreading by starting with the construction of different behavioral decisions.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical m...In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.展开更多
Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision...Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.展开更多
The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environmen...The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systema...At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.展开更多
Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructur...Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructure and composition distribution of the composite interface were investigated.The results show that semi-solid layer with a certain thickness forms near the interface due to the effect of cooling plate,which ensures successful implementation of casting the composite ingot.Two different aluminum alloys are well bonded metallurgically.The mechanical properties of composite interface were measured,the tensile and shearing strengths of composite interface are 105 and 88 MPa,respectively,which proves that the composite interface is a kind of metallurgical bonding.展开更多
As an improvement on the conventional two-layer electrode （active material layerlcurrent collector）, a novel sandwich-like three-layer electrode （conductive layerlactive material layertcurrent collector） for catho...As an improvement on the conventional two-layer electrode （active material layerlcurrent collector）, a novel sandwich-like three-layer electrode （conductive layerlactive material layertcurrent collector） for cathode material LiFePO4/C was introduced in order to improve its electrochemical performance. LiFePO4/C in the three-layer electrode exhibited superior rate capability in comparison with that in the two-layer electrode in accordance with charge-discharge examination. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that Fe3＋/Fe2＋ redox couple for LiFePO4 in the three-layer electrode displayed faster kinetics, better reversibility and much lower charge transfer resistance than that in the two-layer electrode in electrochemical process. For three-layer electrode, the holes in the surface of active material layer were filled by smaller acetylene black grains, which formed electrical connections and provided more pathways to electron transport to/from LiFePO4/C particles exposed to the bulk electrolyte.展开更多
Three-layer6009/7050/6009aluminum alloy clad slab was fabricated by an innovative direct-chill casting process.To study the response of the clad slab to plastic deformation and heat treatments,homogenization annealing...Three-layer6009/7050/6009aluminum alloy clad slab was fabricated by an innovative direct-chill casting process.To study the response of the clad slab to plastic deformation and heat treatments,homogenization annealing,hot rolling,solution and aging were successively performed on the as-cast6009/7050/6009clad samples.The results revealed that excellent metallurgical bonding between7050alloy layer and6009alloy layer was achieved under optimal parameters.The clad ratio obviously decreased when the annealed sample was rolled to55%hot reduction level,and then changed slightly with further rolling.Furthermore,the content of rodlike Zn-rich phases increased significantly in7050alloy layer in the homogenized clad samples after rolling at55%,65%and75%hot reduction levels,and the higher level of hot reduction resulted in narrower diffusion layer.Subsequent solution and aging significantly improved the hardness in7050alloy layer,interfaces and6009alloy layers of the rolled samples except for the thin side for the75%hot reduction sample.展开更多
Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above...Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above by freshwater of finite depth with free surface and below by an infinite layer of water of greater density are considered.In such a situation timeharmonic waves with a given frequency can propagate with three wavenumbers.The sphere is submerged in either of the three layers.Each problem is reduced to an infinite system of linear equations by employing the method of multipoles and the system of equations is solved numerically by standard technique.The hydrodynamic forces(vertical and horizontal forces)are obtained and depicted graphically against the wavenumber.When the density ratio of the upper and middle layer is made to approximately one,curves for vertical and horizontal forces almost coincide with the corresponding curves for the case of a two-layer fluid with a free surface.This means that in the limit,the density ratio of the upper and middle layer goes to approximately one,the solution agrees with the solution for the case of a two-layer fluid with a free surface.展开更多
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
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
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
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funding support from the National Natural Science Foundation of China (Nos. 42477208 and 52079134)the Natural Science Foundation of Hubei Province, China (No. 2024AFA072)+2 种基金the Youth Innovation Promotion Association CAS (No. 2022332)the National Key R&D Program of China (No. 2024YFF0508203)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety (Nos. SKLGME-JBGS2402 and SKLGME022022)。
文摘Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress tensor by measuring strain using an HI strain cell.However,existing analytical solutions for stress calculation based on an HI strain cell in a double-layer medium are not applicable when an HI strain cell is used in a three-layer medium,leading to erroneous stress calculations.To address this issue,this paper presents a method for calculating stress tensors in a three-layer medium using numerical simulations,specifically by obtaining a constitutive matrix that relates strain measurements to stress tensors in a three-layer medium.Furthermore,using Latin hypercube sampling (LHS) and orthogonal experimental design strategies,764 groups of numerical models encompassing various stress measurement scenarios have been established and calculated using FLAC^(3D)software.Finally,a surrogate model based on artificial neural network (ANN) was developed to predict constitutive matrices,achieving a goodness of fit (R^(2)) of 0.999 and a mean squared error (MSE) of 1.254.A software program has been developed from this surrogate model for ease of use in practical engineering applications.The method’s accuracy was verified through numerical simulations,analytical solution and laboratory experiment,demonstrating its effectiveness in calculating stress in a three-layer medium.The surrogate model was applied to calculate mining-induced stress in the roadway roof rock of a coal mine,a typical case for stress measurement in a three-layer medium.Errors in stress calculations arising from the use of existing analytical solutions were corrected.The study also highlights the significant errors associated with using double-layer analytical solutions in a three-layer medium,which could lead to inappropriate engineering design.
基金Project(52276068)supported by the National Natural Science Foundation of China。
文摘This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This research examines the flow of a three-layered viscous fluid,considering the combined influence of heat and solutal buoyancy driven Rayleigh-Bénard convection,as well as thermal and solutal Marangoni convection.The homotopy perturbation method is used to examine and simulate complex fluid flow and transport phenomena,providing important understanding of the fundamental physics and assisting in the optimization of various battery configurations.The inquiry examines the primary elements that influence Marangoni convection and its impact on battery performance,providing insights on possible enhancements in energy storage devices.The findings indicate that the velocity profiles shown graphically exhibit a prominent core zone characterized by the maximum speed,which progressively decreases as it approaches the walls of the channel.This study enhances our comprehension of fluid dynamics and the transmission of heat and mass in intricate systems,which has substantial ramifications for the advancement of sustainable energy solutions.
文摘This paper raises, for the first time, with a model reading passage, a three-layer passage reading method （3LPRM in brief ） in English reading： reading beyond paragraphs; reading within paragraphs and sentences, and reading with coherences of words and expressions. The paper illustrates the definition, contents, characteristics and application of the method which is easy to master and apply. The paper aims at supplying readers especially beginners of E/S/FL （English as second/foreign language） with a practical passage reading method so as to improve their reading efficiency. The paper has some practical significance and directing value.
基金Project supported by the National Natural Science Foundation of China (Grant No. 72174121)the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, and the Soft Science Research Project of Shanghai (Grant No. 22692112600)。
文摘Information plays a crucial role in guiding behavioral decisions during public health emergencies. Individuals communicate to acquire relevant knowledge about an epidemic, which influences their decisions to adopt protective measures.However, whether to disseminate specific information is also a behavioral decision. In light of this understanding, we develop a coupled information–vaccination–epidemic model to depict these co-evolutionary dynamics in a three-layer network. Negative information dissemination and vaccination are treated as separate decision-making processes. We then examine the combined effects of herd and risk motives on information dissemination and vaccination decisions through the lens of game theory. The microscopic Markov chain approach(MMCA) is used to describe the dynamic process and to derive the epidemic threshold. Simulation results indicate that increasing the cost of negative information dissemination and providing timely clarification can effectively control the epidemic. Furthermore, a phenomenon of diminishing marginal utility is observed as the cost of dissemination increases, suggesting that authorities do not need to overinvest in suppressing negative information. Conversely, reducing the cost of vaccination and increasing vaccine efficacy emerge as more effective strategies for outbreak control. In addition, we find that the scale of the epidemic is greater when the herd motive dominates behavioral decision-making. In conclusion, this study provides a new perspective for understanding the complexity of epidemic spreading by starting with the construction of different behavioral decisions.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by Anhui Provincial Natural Science Foundation(2408085QA030)Natural Science Research Project of Anhui Educational Committee,China(2022AH050825)+3 种基金Medical Special Cultivation Project of Anhui University of Science and Technology(YZ2023H2C008)the Excellent Research and Innovation Team of Anhui Province,China(2022AH010052)the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology,China(2021yjrc51)Collaborative Innovation Program of Hefei Science Center,CAS,China(2019HSC-CIP006).
文摘In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.
基金funded by the Beijing Engineering Research Center of Electric Rail Transportation.
文摘Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.
基金supported by the National Key Research and Develop-ment Program(No.2022YFC3701103)the National Natural Science Foundation of China(Nos.42130714 and 41931287).
文摘The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
基金supported by the National Natural Science Foundation of China(Project No.42307555).
文摘At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.
基金Project (2005CB623707) supported by the National Basic Research Program of China
文摘Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructure and composition distribution of the composite interface were investigated.The results show that semi-solid layer with a certain thickness forms near the interface due to the effect of cooling plate,which ensures successful implementation of casting the composite ingot.Two different aluminum alloys are well bonded metallurgically.The mechanical properties of composite interface were measured,the tensile and shearing strengths of composite interface are 105 and 88 MPa,respectively,which proves that the composite interface is a kind of metallurgical bonding.
基金Project(2010ZCO51)supported by Natural Science Foundation of Yunnan ProvinceProject supported by Analysis and Testing Foundation(2009-041)Starting Research Fund(14118245)from Kunming University of Science and Technology
文摘As an improvement on the conventional two-layer electrode （active material layerlcurrent collector）, a novel sandwich-like three-layer electrode （conductive layerlactive material layertcurrent collector） for cathode material LiFePO4/C was introduced in order to improve its electrochemical performance. LiFePO4/C in the three-layer electrode exhibited superior rate capability in comparison with that in the two-layer electrode in accordance with charge-discharge examination. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that Fe3＋/Fe2＋ redox couple for LiFePO4 in the three-layer electrode displayed faster kinetics, better reversibility and much lower charge transfer resistance than that in the two-layer electrode in electrochemical process. For three-layer electrode, the holes in the surface of active material layer were filled by smaller acetylene black grains, which formed electrical connections and provided more pathways to electron transport to/from LiFePO4/C particles exposed to the bulk electrolyte.
基金Projects(51375070,51574058) supported by the National Natural Science Foundation of China
文摘Three-layer6009/7050/6009aluminum alloy clad slab was fabricated by an innovative direct-chill casting process.To study the response of the clad slab to plastic deformation and heat treatments,homogenization annealing,hot rolling,solution and aging were successively performed on the as-cast6009/7050/6009clad samples.The results revealed that excellent metallurgical bonding between7050alloy layer and6009alloy layer was achieved under optimal parameters.The clad ratio obviously decreased when the annealed sample was rolled to55%hot reduction level,and then changed slightly with further rolling.Furthermore,the content of rodlike Zn-rich phases increased significantly in7050alloy layer in the homogenized clad samples after rolling at55%,65%and75%hot reduction levels,and the higher level of hot reduction resulted in narrower diffusion layer.Subsequent solution and aging significantly improved the hardness in7050alloy layer,interfaces and6009alloy layers of the rolled samples except for the thin side for the75%hot reduction sample.
文摘Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above by freshwater of finite depth with free surface and below by an infinite layer of water of greater density are considered.In such a situation timeharmonic waves with a given frequency can propagate with three wavenumbers.The sphere is submerged in either of the three layers.Each problem is reduced to an infinite system of linear equations by employing the method of multipoles and the system of equations is solved numerically by standard technique.The hydrodynamic forces(vertical and horizontal forces)are obtained and depicted graphically against the wavenumber.When the density ratio of the upper and middle layer is made to approximately one,curves for vertical and horizontal forces almost coincide with the corresponding curves for the case of a two-layer fluid with a free surface.This means that in the limit,the density ratio of the upper and middle layer goes to approximately one,the solution agrees with the solution for the case of a two-layer fluid with a free surface.
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.
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.
