An adaptive EFG-FE coupling method is proposed and developed for the numerical simulation of lateral extrusion and forward-backward extrusion. Initially, the simulation has been implemented by using a conventional FE ...An adaptive EFG-FE coupling method is proposed and developed for the numerical simulation of lateral extrusion and forward-backward extrusion. Initially, the simulation has been implemented by using a conventional FE model. During the deforming process, mesh quality is checked at every incremental step. Distorted elements are automatically converted to EFG nodes, whereas, the less distorted elements are reserved. A new algorithm to generate EFG nodes and interface elements is presented. This method is capable of dealing with large deformation and has higher computational efficiency than using an EFG method wholly. Numerical results demonstrate that the adaptive EFG-FE coupling method has reasonable accuracy and is effective for local bulk metal forming such as extrusion processes.展开更多
The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor...The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.展开更多
A three-dimensional (3-D) coupled physical and biological model was used to investigate the physical processes and their influence on the ecosystem dynamics of the Bohai Sea of China. The physical processes include ...A three-dimensional (3-D) coupled physical and biological model was used to investigate the physical processes and their influence on the ecosystem dynamics of the Bohai Sea of China. The physical processes include M2 tide, time - varying wind forcing and river discharge. Wind records from 1 to 31 May in 1993 were selected to force the model. The biological model is based on a simple, nitrate and phosphate limited, lower trophic food web system. The simulated results showed that variation of residual currents forced by M2 tide, fiver discharge and time-varying wind had great impact on the distribution of phytoplankton biomass in the Laizhou Bay. High phytoplankton biomass appeared in the upwelling region. Numerical experiments based on the barotropic model and baroclinic model with no wind and water discharge were also conducted. Differences in the results by the baroclinic model and the barotropic model were significant: more patches appeared in the baroclinic model comparing with the barotropic model. And in the baroclinic model, the subsurface maximum phytoplankton biomass patches formed in the stratified water.展开更多
The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic re...The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.展开更多
The greatest challenges of rigorously modeling coupled hydro-mechanical(HM)processes in fractured geological media at different scales are associated with computational geometry.These challenges include dynamic sheari...The greatest challenges of rigorously modeling coupled hydro-mechanical(HM)processes in fractured geological media at different scales are associated with computational geometry.These challenges include dynamic shearing and opening of intersecting fractures at discrete fracture scales as a result of coupled processes,and contact alteration along rough fracture surfaces that triggers structural and physical changes of fractures at micro-asperity scale.In this paper,these challenges are tackled by developing a comprehensive modeling approach for coupled processes in fractured geological media based on numerical manifold method(NMM)at multiple scales.Based on their distinct geometric features,fractures are categorized into three different scales:dominant fracture,discrete fracture,and discontinuum asperity scales.Here the scale is relative,that of the fracture relative to that of the research interest or domain.Different geometric representations of fractures at different scales are used,and different governing equations and constitutive relationships are applied.For dominant fractures,a finite thickness zone model is developed to treat a fracture as a porous nonlinear domain.Nonlinear fracture mechanical behavior is accurately modeled with an implicit approach based on strain energy.For discrete fractures,a zero-dimensional model was developed for analyzing fluid flow and mechanics in fractures that are geometrically treated as boundaries of the rock matrix.With the zero-dimensional model,these fractures can be modeled with arbitrary orientations and intersections.They can be fluid conduits or seals,and can be open,bonded or sliding.For the discontinuum asperity scale,the geometry of rough fracture surfaces is explicitly represented and contacts involving dynamic alteration of contacts among asperities are rigorously calculated.Using this approach,fracture alteration caused by deformation,re-arrangement and sliding of rough surfaces can be captured.Our comprehensive model is able to handle the computational challenges with accurate representation of intersections and shearing of fractures at the discrete fracture scale and rigorously treats contacts along rough fracture surfaces at the discontinuum asperity scale.With future development of three-dimensional(3D)geometric representation of discrete fracture networks in porous rock and contacts among multi-body systems,this model is promising as a basis of 3D fully coupled analysis of fractures at multiple scales,for advancing understanding and optimizing energy recovery and storage in fractured geological media.展开更多
The production and energy coupling system is used to mainly present energy flow, material flow, information flow, and their coupling interaction. Through the modeling and simulation of this system, the performance of ...The production and energy coupling system is used to mainly present energy flow, material flow, information flow, and their coupling interaction. Through the modeling and simulation of this system, the performance of energy flow can be analyzed and optimized in the process industry. In order to study this system, the component based hybrid Petri net methodology (CpnHPN) is proposed, synthesizing a number of extended Petri net methods and using the concept of energy place, material place, and information place. Through the interface place in CpnHPN, the component based encapsulation is established, which enables the production and energy coupling system to be built, analyzed, and optimized on the multi-level framework. Considering the block and brief simulation for hybrid system, the CpnHPN model is simulated with Simulink/Stateflow. To illustrate the use of the proposed methodology, the application of CpnHPN in the energy optimization of chlorine balance system is provided.展开更多
The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the def...The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.展开更多
The West Antarctic Peninsula(WAP)region is one of the most productive marine ecosystems in the Southern Ocean that support the food web for phytoplankton,krill spawning or recruitment and several krill consumers at hi...The West Antarctic Peninsula(WAP)region is one of the most productive marine ecosystems in the Southern Ocean that support the food web for phytoplankton,krill spawning or recruitment and several krill consumers at higher-trophic level like penguins and Antarctic fur seals.Characterized by channels and islands,the complex topography of the WAP generates interconnected circulation patterns,strongly influencing vertical stratification,nutrient availability and distribution of marine organisms.Additionally,rapid climate change associated with major climate modes like the Southern Annular Mode(SAM)and El Niño-Southern Oscillation(ENSO)has significant effects on long-term variations of physical environments and biological production.The objective of this study is to reveal the spatial-temporal variations of phytoplankton biomass in the WAP region and the modulating physical-ecological processes.By using 9-year hydrographic and ecological data of five transects collected by the Palmer Long-Term Ecosystem Research,the horizontal and vertical distributions of several physical and ecological properties,with a particular focus on chlorophyll(Chl)concentration were explored.Regression analysis among area-averaged properties and properties at single stations was performed to reveal the relationship between the interannual variations of physical and ecological processes.The correlation results showed that Chl concentration exhibited a positive relationship with both the circumpolar deep water(CDW)intrusion and vertical stratification,but showed a negative correlation with SAM at some specific stations.However,certain processes or mechanisms may only be dominant for specific stations and not applicable to the entire region.No single physical or ecological factors have been found to significantly influence the Chl distribution throughout the WAP region,which may be attributed to the heterogeneity of sea ice conditions,geometry and hydrodynamic features as well as variations in nutrient sources.展开更多
Basin-mountain coupling is a key issue for basin formation and evolution. The analysis of basin-mountain coupling process, as well as quantitative or semiquantitative restoration of prototype basin and the evolution o...Basin-mountain coupling is a key issue for basin formation and evolution. The analysis of basin-mountain coupling process, as well as quantitative or semiquantitative restoration of prototype basin and the evolution of continental margin, can be used to interpret the geological process of basin-range conversion and reconstruct early prototype basins, which is a difficult and leadin~ scientific oroblem of basin research.展开更多
The coupled thermo-hydro-mechanical and chemical (THMC) processes of stress/deformation,fluid flow,temperature and geochemical reactions of the geological media,namely fractured rocks and soils,play an important role ...The coupled thermo-hydro-mechanical and chemical (THMC) processes of stress/deformation,fluid flow,temperature and geochemical reactions of the geological media,namely fractured rocks and soils,play an important role in design,construction,operation and environmental impact assessments of rock and soil engineering works such as underground nuclear waste repositories,oil/gas production and storage,geothermal energy extraction,landslides and slope stability,hydropower and water conservancy complexes,etc. This paper presents an overview of the international and Chinese experiences in numerical modeling of the coupled THMC processes for both the state-of-the-knowledge,remaining challenges and possible future prospects.展开更多
Based on the theory of elastic-plastic finite element method, the high-speed hot continuous rolling process of a billet is simulated and analyzed in vertical and horizontal passes. The billet is dragged into the passe...Based on the theory of elastic-plastic finite element method, the high-speed hot continuous rolling process of a billet is simulated and analyzed in vertical and horizontal passes. The billet is dragged into the passes by contact friction force between the billet and rollers. The rollers and billet are represented by respectively rigid and deformable bodies, and three-dimensional models are developed for the billet and rollers. The distribution of deformation field, effective strain, rolling force and temperature field are accurately calculated for the whole rolling process (including unstable and stable stages). In addition, the rolling pressure on the width symmetry center is compared with that in the in-situ experimental measurements. It is revealed that various heat exchange phenomena among the billet, rollers and surroundings can result in unbalanced temperature distribution on the cross section. Rolling force and strain can change significantly when the billet is moved towards or away from the roller gap, and keep almost invariable in the stable stage. It is expected that the simulation results would be useful for practical manufacture and provide the theoretical foundation for improvement of process planning and optimization of process parameters.展开更多
Decoupling the complicated vibrational-vibrational (V-V) coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our pre...Decoupling the complicated vibrational-vibrational (V-V) coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 (2012)], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.展开更多
CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulf...CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulfuric acid deposited on the porous support. The above process can be expressed as follows: CS2 H2O→ COS H2O→ H2S O2→ S/SO4^2-. H2S oxidation eliminates its prohibition on C52 hydrolysis so that the rate of coupling removal CS2 is 5 times higher than that of CS2 hydrolysis. The same active energy of hydrolysis and coupling reaction also indicates that HES oxidation does not change the reaction mechanism of CS2 hydrolysis. Temperature has obvious effect on the process while the mole ratio of O2 concentration to CS2 concentration (O/S) does not, especially in excess of 2.5. The formation of sulfuric acid on the catalyst surface poisons hydrolysis active sites and causes the decrease of left OH^-1 concentration on the catalysts surface. Lower temperature is suggested for this bi-functional catalyst owing to the low yield ratio of S/SO4^2-.展开更多
The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and ...The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies.展开更多
The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical(THM) coupling phenomena and their influences on the repository safety.In this paper,the high-level waste(HLW) disposal con...The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical(THM) coupling phenomena and their influences on the repository safety.In this paper,the high-level waste(HLW) disposal concept in drifts in clay formation with backfilled bentonite buffer is represented numerically using the CODE BRIGHT developed by the Technical University of Catalonia in Barcelona.The parameters of clay and bentonite used in the simulation are determined by laboratory and in situ experiments.The calculation results are presented to show the hydro-mechanical(HM) processes during the operation phase and the THM processes in the after-closure phase.According to the simulation results,the most probable critical processes for the disposal project have been represented and analyzed.The work also provides an input for additional development regarding the design,assessment and validation of the HLW disposal concept.展开更多
The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element met...The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element method and the finite difference method). By matching the theoretical calculation to an experiment, the nonlinear problem was analyzed and the variable thermophysical parameters concerned was evaluated. The analysis procedure and the evaluation of the parameters were presented in detail. The result of the study showed that by using the method as described in the paper, it was possible to determine the variable (with respect to temperature, moisture content and freezing state) thermophysical parameters which were unknown or difficult to measure as long as the governing equations for a considered process were available. The method can significantly reduces the experiment efforts for determining thermophysical parameters which arc very complicated to measure. The determined variable of the effective heat conductivity of wood particle material was given in the paper. The error of the numerical calculation was also estimated by the comparison with a matched experiment.展开更多
Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global warming. In this study the coupled heat and mass transfer model for(Coup Model) the soil-plant-atmosphere-system...Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global warming. In this study the coupled heat and mass transfer model for(Coup Model) the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the Coup Model for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the Qinghai-Tibet Plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination(R2) is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0–20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water exchanges between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thawing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide protection against active layer deepening in summer, so climate warming will cause the permafrost active layer to become deeper and permafrost degradation.展开更多
Coupling-induced logical stochastic resonance(LSR) can be observed in a noise-driven coupled bistable system where the behaviors of system can be interpreted consistently as a specific logic gate in an appropriate noi...Coupling-induced logical stochastic resonance(LSR) can be observed in a noise-driven coupled bistable system where the behaviors of system can be interpreted consistently as a specific logic gate in an appropriate noise level. Here constant coupling is extended to time-varying coupling, and then we investigate the effect of time-varying coupling on LSR in a periodically driven coupled bistable system. When coupling intensity oscillates periodically with the same frequency with periodic force or relatively high frequency, the system successfully yields the desired logic output. When coupling intensity oscillates irregularly with phase disturbance, large phase disturbance reduces the area of optimal parameter region of coupling intensity and response speed of logic devices. Although the system behaves as a desired logic gate when the frequency of time-periodic coupling intensity is precisely equal to that of periodic force, the desired logic gate is not robust against tiny frequency difference and phase disturbance. Therefore, periodic coupling intensity with high frequency ratio is an optimal option to obtain a reliable and robust logic operation.展开更多
A two-dimensional (2D) fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma (CCP) reactor. The plasma–wall interaction ...A two-dimensional (2D) fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma (CCP) reactor. The plasma–wall interaction (including the deposition) is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N2 /NH3 ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing the electron density significantly.展开更多
基金National Natural Science Foundation of China(No.50575143)Specialized Research Fund for the Doctoral Program of HigherEducation (No.20040248005).
文摘An adaptive EFG-FE coupling method is proposed and developed for the numerical simulation of lateral extrusion and forward-backward extrusion. Initially, the simulation has been implemented by using a conventional FE model. During the deforming process, mesh quality is checked at every incremental step. Distorted elements are automatically converted to EFG nodes, whereas, the less distorted elements are reserved. A new algorithm to generate EFG nodes and interface elements is presented. This method is capable of dealing with large deformation and has higher computational efficiency than using an EFG method wholly. Numerical results demonstrate that the adaptive EFG-FE coupling method has reasonable accuracy and is effective for local bulk metal forming such as extrusion processes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11447165,11373047 and 11265009the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2016056
文摘The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.
基金This work was supported by the National Natural Science Foundation of China under contract Nos 40531006 and 40376039; LOPSO Open Fund of the Second Institute of Oceanography of State Oceanic Administration;Part of the work was conducted at the Marine Department of University of Georgia USA.
文摘A three-dimensional (3-D) coupled physical and biological model was used to investigate the physical processes and their influence on the ecosystem dynamics of the Bohai Sea of China. The physical processes include M2 tide, time - varying wind forcing and river discharge. Wind records from 1 to 31 May in 1993 were selected to force the model. The biological model is based on a simple, nitrate and phosphate limited, lower trophic food web system. The simulated results showed that variation of residual currents forced by M2 tide, fiver discharge and time-varying wind had great impact on the distribution of phytoplankton biomass in the Laizhou Bay. High phytoplankton biomass appeared in the upwelling region. Numerical experiments based on the barotropic model and baroclinic model with no wind and water discharge were also conducted. Differences in the results by the baroclinic model and the barotropic model were significant: more patches appeared in the baroclinic model comparing with the barotropic model. And in the baroclinic model, the subsurface maximum phytoplankton biomass patches formed in the stratified water.
基金the support from Clariant International Ltd.the National Natural Science Foundation of China (Nos.22022811,21938008,and U21B2096)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.
基金supported by Laboratory Directed Research and Development(LDRD)funding from Berkeley Labsupported by Open Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z017004)。
文摘The greatest challenges of rigorously modeling coupled hydro-mechanical(HM)processes in fractured geological media at different scales are associated with computational geometry.These challenges include dynamic shearing and opening of intersecting fractures at discrete fracture scales as a result of coupled processes,and contact alteration along rough fracture surfaces that triggers structural and physical changes of fractures at micro-asperity scale.In this paper,these challenges are tackled by developing a comprehensive modeling approach for coupled processes in fractured geological media based on numerical manifold method(NMM)at multiple scales.Based on their distinct geometric features,fractures are categorized into three different scales:dominant fracture,discrete fracture,and discontinuum asperity scales.Here the scale is relative,that of the fracture relative to that of the research interest or domain.Different geometric representations of fractures at different scales are used,and different governing equations and constitutive relationships are applied.For dominant fractures,a finite thickness zone model is developed to treat a fracture as a porous nonlinear domain.Nonlinear fracture mechanical behavior is accurately modeled with an implicit approach based on strain energy.For discrete fractures,a zero-dimensional model was developed for analyzing fluid flow and mechanics in fractures that are geometrically treated as boundaries of the rock matrix.With the zero-dimensional model,these fractures can be modeled with arbitrary orientations and intersections.They can be fluid conduits or seals,and can be open,bonded or sliding.For the discontinuum asperity scale,the geometry of rough fracture surfaces is explicitly represented and contacts involving dynamic alteration of contacts among asperities are rigorously calculated.Using this approach,fracture alteration caused by deformation,re-arrangement and sliding of rough surfaces can be captured.Our comprehensive model is able to handle the computational challenges with accurate representation of intersections and shearing of fractures at the discrete fracture scale and rigorously treats contacts along rough fracture surfaces at the discontinuum asperity scale.With future development of three-dimensional(3D)geometric representation of discrete fracture networks in porous rock and contacts among multi-body systems,this model is promising as a basis of 3D fully coupled analysis of fractures at multiple scales,for advancing understanding and optimizing energy recovery and storage in fractured geological media.
基金Shanghai Municipal Science & Technology Projects, China (No. 09DZ1203300, No. 10JC1415200)
文摘The production and energy coupling system is used to mainly present energy flow, material flow, information flow, and their coupling interaction. Through the modeling and simulation of this system, the performance of energy flow can be analyzed and optimized in the process industry. In order to study this system, the component based hybrid Petri net methodology (CpnHPN) is proposed, synthesizing a number of extended Petri net methods and using the concept of energy place, material place, and information place. Through the interface place in CpnHPN, the component based encapsulation is established, which enables the production and energy coupling system to be built, analyzed, and optimized on the multi-level framework. Considering the block and brief simulation for hybrid system, the CpnHPN model is simulated with Simulink/Stateflow. To illustrate the use of the proposed methodology, the application of CpnHPN in the energy optimization of chlorine balance system is provided.
基金[This work was financially supported by a research grant from the Hong Kong Polytechnic University (No.G-V694).]
文摘The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.
基金supported by the National Natural Science Foundation of China(Grant nos.41941008 and 41876221)the National Key Research and Development Program of China(Grant no.2022YFC2807601).
文摘The West Antarctic Peninsula(WAP)region is one of the most productive marine ecosystems in the Southern Ocean that support the food web for phytoplankton,krill spawning or recruitment and several krill consumers at higher-trophic level like penguins and Antarctic fur seals.Characterized by channels and islands,the complex topography of the WAP generates interconnected circulation patterns,strongly influencing vertical stratification,nutrient availability and distribution of marine organisms.Additionally,rapid climate change associated with major climate modes like the Southern Annular Mode(SAM)and El Niño-Southern Oscillation(ENSO)has significant effects on long-term variations of physical environments and biological production.The objective of this study is to reveal the spatial-temporal variations of phytoplankton biomass in the WAP region and the modulating physical-ecological processes.By using 9-year hydrographic and ecological data of five transects collected by the Palmer Long-Term Ecosystem Research,the horizontal and vertical distributions of several physical and ecological properties,with a particular focus on chlorophyll(Chl)concentration were explored.Regression analysis among area-averaged properties and properties at single stations was performed to reveal the relationship between the interannual variations of physical and ecological processes.The correlation results showed that Chl concentration exhibited a positive relationship with both the circumpolar deep water(CDW)intrusion and vertical stratification,but showed a negative correlation with SAM at some specific stations.However,certain processes or mechanisms may only be dominant for specific stations and not applicable to the entire region.No single physical or ecological factors have been found to significantly influence the Chl distribution throughout the WAP region,which may be attributed to the heterogeneity of sea ice conditions,geometry and hydrodynamic features as well as variations in nutrient sources.
基金supported by the National Science Foundation of China(grant No.41476053)the China Geological Project(grants No.GZH201400214 and DD20160153)
文摘Basin-mountain coupling is a key issue for basin formation and evolution. The analysis of basin-mountain coupling process, as well as quantitative or semiquantitative restoration of prototype basin and the evolution of continental margin, can be used to interpret the geological process of basin-range conversion and reconstruct early prototype basins, which is a difficult and leadin~ scientific oroblem of basin research.
基金Supported by the Special Funds fo Major State Basic Research Project (2002CB412708).
文摘The coupled thermo-hydro-mechanical and chemical (THMC) processes of stress/deformation,fluid flow,temperature and geochemical reactions of the geological media,namely fractured rocks and soils,play an important role in design,construction,operation and environmental impact assessments of rock and soil engineering works such as underground nuclear waste repositories,oil/gas production and storage,geothermal energy extraction,landslides and slope stability,hydropower and water conservancy complexes,etc. This paper presents an overview of the international and Chinese experiences in numerical modeling of the coupled THMC processes for both the state-of-the-knowledge,remaining challenges and possible future prospects.
基金Funded by National Natural Science Foundation of China (No. 51004047)Scientific Research Fund of Hunan Provincial Education Department (No. 10B020)Provincial Natural Science Foundation of Hunan (No. 09jj4024)
文摘Based on the theory of elastic-plastic finite element method, the high-speed hot continuous rolling process of a billet is simulated and analyzed in vertical and horizontal passes. The billet is dragged into the passes by contact friction force between the billet and rollers. The rollers and billet are represented by respectively rigid and deformable bodies, and three-dimensional models are developed for the billet and rollers. The distribution of deformation field, effective strain, rolling force and temperature field are accurately calculated for the whole rolling process (including unstable and stable stages). In addition, the rolling pressure on the width symmetry center is compared with that in the in-situ experimental measurements. It is revealed that various heat exchange phenomena among the billet, rollers and surroundings can result in unbalanced temperature distribution on the cross section. Rolling force and strain can change significantly when the billet is moved towards or away from the roller gap, and keep almost invariable in the stable stage. It is expected that the simulation results would be useful for practical manufacture and provide the theoretical foundation for improvement of process planning and optimization of process parameters.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60971009 and 61001011)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090142110019)+1 种基金the Natural Science Foundation of Hubei Province, China (Grant No. 2010CDB02701)the Fundamental Research Funds for the Central Universities, China (Grant No. 2012QN083)
文摘Decoupling the complicated vibrational-vibrational (V-V) coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 (2012)], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.
文摘CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulfuric acid deposited on the porous support. The above process can be expressed as follows: CS2 H2O→ COS H2O→ H2S O2→ S/SO4^2-. H2S oxidation eliminates its prohibition on C52 hydrolysis so that the rate of coupling removal CS2 is 5 times higher than that of CS2 hydrolysis. The same active energy of hydrolysis and coupling reaction also indicates that HES oxidation does not change the reaction mechanism of CS2 hydrolysis. Temperature has obvious effect on the process while the mole ratio of O2 concentration to CS2 concentration (O/S) does not, especially in excess of 2.5. The formation of sulfuric acid on the catalyst surface poisons hydrolysis active sites and causes the decrease of left OH^-1 concentration on the catalysts surface. Lower temperature is suggested for this bi-functional catalyst owing to the low yield ratio of S/SO4^2-.
基金MGMR Eighth Five- Year Plan Basic Geology Research Foundation Grant 8502216China National Natural Science Foundation Grant 49173169
文摘The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies.
基金financed and supported by the German research institute "Gesellschaft für Anlagen-und Reaktorsicherheit (GRS) mbH"
文摘The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical(THM) coupling phenomena and their influences on the repository safety.In this paper,the high-level waste(HLW) disposal concept in drifts in clay formation with backfilled bentonite buffer is represented numerically using the CODE BRIGHT developed by the Technical University of Catalonia in Barcelona.The parameters of clay and bentonite used in the simulation are determined by laboratory and in situ experiments.The calculation results are presented to show the hydro-mechanical(HM) processes during the operation phase and the THM processes in the after-closure phase.According to the simulation results,the most probable critical processes for the disposal project have been represented and analyzed.The work also provides an input for additional development regarding the design,assessment and validation of the HLW disposal concept.
文摘The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element method and the finite difference method). By matching the theoretical calculation to an experiment, the nonlinear problem was analyzed and the variable thermophysical parameters concerned was evaluated. The analysis procedure and the evaluation of the parameters were presented in detail. The result of the study showed that by using the method as described in the paper, it was possible to determine the variable (with respect to temperature, moisture content and freezing state) thermophysical parameters which were unknown or difficult to measure as long as the governing equations for a considered process were available. The method can significantly reduces the experiment efforts for determining thermophysical parameters which arc very complicated to measure. The determined variable of the effective heat conductivity of wood particle material was given in the paper. The error of the numerical calculation was also estimated by the comparison with a matched experiment.
基金National Major Scientific Project of China(No.2013CBA01803)Science Fund for Creative Research Groups of National Natural Science Foundation of China(No.41121001)+1 种基金National Natural Science Foundation of China(No.41271081)Foundation of One Hundred Person Project of Chinese Academy of Sciences(No.51Y251571)
文摘Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global warming. In this study the coupled heat and mass transfer model for(Coup Model) the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the Coup Model for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the Qinghai-Tibet Plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination(R2) is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0–20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water exchanges between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thawing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide protection against active layer deepening in summer, so climate warming will cause the permafrost active layer to become deeper and permafrost degradation.
基金supported by the National Natural Science Foundation of China (Grant No. 31601071)。
文摘Coupling-induced logical stochastic resonance(LSR) can be observed in a noise-driven coupled bistable system where the behaviors of system can be interpreted consistently as a specific logic gate in an appropriate noise level. Here constant coupling is extended to time-varying coupling, and then we investigate the effect of time-varying coupling on LSR in a periodically driven coupled bistable system. When coupling intensity oscillates periodically with the same frequency with periodic force or relatively high frequency, the system successfully yields the desired logic output. When coupling intensity oscillates irregularly with phase disturbance, large phase disturbance reduces the area of optimal parameter region of coupling intensity and response speed of logic devices. Although the system behaves as a desired logic gate when the frequency of time-periodic coupling intensity is precisely equal to that of periodic force, the desired logic gate is not robust against tiny frequency difference and phase disturbance. Therefore, periodic coupling intensity with high frequency ratio is an optimal option to obtain a reliable and robust logic operation.
基金Project supported by the China Postdoctoral Science Foundation (Grant No. 2012M511603)the National Natural Science Foundation of China (Grant Nos. 11105057 and 10775025)+1 种基金the Natural Science Foundation of Hubei Province of China (Grant No. 2007ABA035)the Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0073)
文摘A two-dimensional (2D) fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma (CCP) reactor. The plasma–wall interaction (including the deposition) is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N2 /NH3 ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing the electron density significantly.