A reduced three-degree-of-freedom model simulating the fluid-structure interactions （FSI） of the turbine blades and the on- coming air flows is proposed. The equations of motions consist of the coupling of bending a...A reduced three-degree-of-freedom model simulating the fluid-structure interactions （FSI） of the turbine blades and the on- coming air flows is proposed. The equations of motions consist of the coupling of bending and torsion of a blade as well as a van der Pol oscillation which represents the time-varying of the fluid. The 1：1 internal resonance of the system is analyzed with the multiple scale method, and the modulation equations are derived. The two-parameter bifurcation diagrams are computed. The effects of the system parameters, including the detuning parameter and the reduced frequency, on responses of the struc- ture and fluid are investigated. Bifurcation curves are computed and the stability is determined by examining the eigenvalues of the Jacobian matrix. The results indicate that rich dynamic phenomena of the steady-state solutions including the sad- dle-node and Hopf bifurcations can occur under certain parameter conditions. The parameter region where the unstable solu- tions occur should be avoided to keep the safe operation of the blades. The analytical solutions are verified by the direct nu- merical simulations.展开更多
In the aggressive marine environment over a long-term service period,coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity.This paper investigates the strength reduction of coas...In the aggressive marine environment over a long-term service period,coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity.This paper investigates the strength reduction of coastal bridges,especially focusing on the effects of non-uniform corrosion along the height of bridge piers.First,the corrosion initiation time and the degradation of reinforcement and concrete are analyzed for bridge piers in marine environments.To investigate the various damage modes of the concrete cover,a discretization method with fiber cells is used for calculating time-dependent interaction diagrams of cross-sections of the bridge piers at the atmospheric zone and the splash and tidal zone under a combination of axial force and bending moment.Second,the shear strength of these aging structures is analyzed.Numerical simulation indicates that the strength of a concrete pier experiences dramatic reduction from corrosion initiation to the spalling of the concrete cover.Strength loss in the splash and tidal zone is more significant than in the atmospheric zone when structures’service time is assumed to be the same.展开更多
Displacement control algorithms commonly used to evaluate axial force-bending moment(PM)diagrams may lead to incorrect interpretations of the strength envelopes for asymmetric sections.This paper aims to offer valuabl...Displacement control algorithms commonly used to evaluate axial force-bending moment(PM)diagrams may lead to incorrect interpretations of the strength envelopes for asymmetric sections.This paper aims to offer valuable insights by comparing existing displacement control algorithms with a newly proposed force control algorithm.The main focus is on the PM diagrams of three example sections that exhibit varying degrees of asymmetry.The comparative study indicates that conventional displacement control algorithms inevitably introduce non-zero out-of-plane bending moments.The reported PM diagram in such cases erroneously neglects the out-of-plane moment and fails to represent the strength envelope accurately.This oversight results in significant and unconservative errors when verifying the strength of asymmetric sections.展开更多
To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of indust...To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.展开更多
The ternary phase diagrams of polyetherimide （PEI）/N,N-dimethylacetamide （DMAc） with H2O and BuOH as non-solvent were simulated using solubility parameter and Flory-Huggins theory. The phase diagrams show that 5.5...The ternary phase diagrams of polyetherimide （PEI）/N,N-dimethylacetamide （DMAc） with H2O and BuOH as non-solvent were simulated using solubility parameter and Flory-Huggins theory. The phase diagrams show that 5.5% H2O/BuOH system containing 5% BuOH and 0.5% H2O or 6.5% H2O/BuOH system containing 6.2% BuOH and 0.3% H2O is required to induce liquid- liquid demixing for 20 wt-% PEI/DMAc casting solution. Therefore, BuOH can enhance the phase separation of the PEI casting solution and hereby induce higher porosity of the membrane, and the diffusion of BuOH into the water coagulation bath causes larger pore size easily compared with DMAc. Our predictions that the membrane pure water flux first increases then decreases, and the rejection ratio of bovine serum albumin decreases with the increasing concentration of BuOH were validated by the experiments using the prepared membranes.展开更多
Based on the analysis of element correlation,the Gibbs diagram,hydro-geochemical ion ratios,isoline maps of groundwater and soil,and change patterns of strontium content after normalization,the study examines water-ro...Based on the analysis of element correlation,the Gibbs diagram,hydro-geochemical ion ratios,isoline maps of groundwater and soil,and change patterns of strontium content after normalization,the study examines water-rock interaction of shallow groundwater in Dingtao area.The results suggest that strontium in the study area mainly comes from waterrock interactions,and the strata interacting with groundwater are the top of Quaternary and Neogene.The element correlation analysis shows that the formation of strontium-rich groundwater is sufficiently affected by sulfate and carbonate.The Gibbs diagram suggests that the chemical composition of groundwater is mainly influenced by water-rock interactions,accompanied by evaporation crystallization.c(Ca2++Mg2+)/c(HCO3-+SO42-)reflects that the main reactions in the groundwater system is weathering dissolution of carbonate and sulfate,and ion exchange takes place.c(Na+)/c(Cl-)indicates that Na+in groundwater may have waterrock interactions with rocks it flows through.c(Cl-)/c(Ca2+)indicates that the hydrodynamic condition in the pumping well is poor and the water circulation is slow.The study examines the macro isoline map change patterns,correlation curves of change of strontium content in groundwater and shallow soil,and correlation curves of change of strontium content in groundwater,shallow soil,and deep soil.The results suggest that the strontium content in the study area has the same change pattern in groundwater and in soil,which further indicates that strontium in the study area comes from water-rock interactions.展开更多
基金supported by the National Basic Research Program of China(“973” Project)(Grant No.2015CB057405)the National Natural Science Foundation of China(Grant No.11372082)the State Scholarship Fund of CSC
文摘A reduced three-degree-of-freedom model simulating the fluid-structure interactions （FSI） of the turbine blades and the on- coming air flows is proposed. The equations of motions consist of the coupling of bending and torsion of a blade as well as a van der Pol oscillation which represents the time-varying of the fluid. The 1：1 internal resonance of the system is analyzed with the multiple scale method, and the modulation equations are derived. The two-parameter bifurcation diagrams are computed. The effects of the system parameters, including the detuning parameter and the reduced frequency, on responses of the struc- ture and fluid are investigated. Bifurcation curves are computed and the stability is determined by examining the eigenvalues of the Jacobian matrix. The results indicate that rich dynamic phenomena of the steady-state solutions including the sad- dle-node and Hopf bifurcations can occur under certain parameter conditions. The parameter region where the unstable solu- tions occur should be avoided to keep the safe operation of the blades. The analytical solutions are verified by the direct nu- merical simulations.
基金National Natural Science Foundation of China under Grant No.51678197the Major State Basic Research Development Program of China(973 Program)under Grant No.2011CB013604Fundamental Research Funds for the Central Universities of China with Grant No.HIT.BRETIV.201320
文摘In the aggressive marine environment over a long-term service period,coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity.This paper investigates the strength reduction of coastal bridges,especially focusing on the effects of non-uniform corrosion along the height of bridge piers.First,the corrosion initiation time and the degradation of reinforcement and concrete are analyzed for bridge piers in marine environments.To investigate the various damage modes of the concrete cover,a discretization method with fiber cells is used for calculating time-dependent interaction diagrams of cross-sections of the bridge piers at the atmospheric zone and the splash and tidal zone under a combination of axial force and bending moment.Second,the shear strength of these aging structures is analyzed.Numerical simulation indicates that the strength of a concrete pier experiences dramatic reduction from corrosion initiation to the spalling of the concrete cover.Strength loss in the splash and tidal zone is more significant than in the atmospheric zone when structures’service time is assumed to be the same.
基金supported by the Natural Science Foundation of China(52122811).
文摘Displacement control algorithms commonly used to evaluate axial force-bending moment(PM)diagrams may lead to incorrect interpretations of the strength envelopes for asymmetric sections.This paper aims to offer valuable insights by comparing existing displacement control algorithms with a newly proposed force control algorithm.The main focus is on the PM diagrams of three example sections that exhibit varying degrees of asymmetry.The comparative study indicates that conventional displacement control algorithms inevitably introduce non-zero out-of-plane bending moments.The reported PM diagram in such cases erroneously neglects the out-of-plane moment and fails to represent the strength envelope accurately.This oversight results in significant and unconservative errors when verifying the strength of asymmetric sections.
基金supported by the National Natural Science Foundation of China (No.52064029)Yunling Scholarship of Yunnan Province Ten-Thousand Plan,China (No.KKRC201952012)Yunnan Province Ten Thousand Talents Program-Youth Top Talent Project,China (No.2018-73)。
文摘To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.
文摘The ternary phase diagrams of polyetherimide （PEI）/N,N-dimethylacetamide （DMAc） with H2O and BuOH as non-solvent were simulated using solubility parameter and Flory-Huggins theory. The phase diagrams show that 5.5% H2O/BuOH system containing 5% BuOH and 0.5% H2O or 6.5% H2O/BuOH system containing 6.2% BuOH and 0.3% H2O is required to induce liquid- liquid demixing for 20 wt-% PEI/DMAc casting solution. Therefore, BuOH can enhance the phase separation of the PEI casting solution and hereby induce higher porosity of the membrane, and the diffusion of BuOH into the water coagulation bath causes larger pore size easily compared with DMAc. Our predictions that the membrane pure water flux first increases then decreases, and the rejection ratio of bovine serum albumin decreases with the increasing concentration of BuOH were validated by the experiments using the prepared membranes.
基金This paper was supported by project of Customized Agricultural Geological Survey and Evaluation of Yam-Growing Regions in Heze Area of Dingtao County in Shangdong Province from 2016 Heze Ministry of Natural Resource’s financial project at the municipal level.
文摘Based on the analysis of element correlation,the Gibbs diagram,hydro-geochemical ion ratios,isoline maps of groundwater and soil,and change patterns of strontium content after normalization,the study examines water-rock interaction of shallow groundwater in Dingtao area.The results suggest that strontium in the study area mainly comes from waterrock interactions,and the strata interacting with groundwater are the top of Quaternary and Neogene.The element correlation analysis shows that the formation of strontium-rich groundwater is sufficiently affected by sulfate and carbonate.The Gibbs diagram suggests that the chemical composition of groundwater is mainly influenced by water-rock interactions,accompanied by evaporation crystallization.c(Ca2++Mg2+)/c(HCO3-+SO42-)reflects that the main reactions in the groundwater system is weathering dissolution of carbonate and sulfate,and ion exchange takes place.c(Na+)/c(Cl-)indicates that Na+in groundwater may have waterrock interactions with rocks it flows through.c(Cl-)/c(Ca2+)indicates that the hydrodynamic condition in the pumping well is poor and the water circulation is slow.The study examines the macro isoline map change patterns,correlation curves of change of strontium content in groundwater and shallow soil,and correlation curves of change of strontium content in groundwater,shallow soil,and deep soil.The results suggest that the strontium content in the study area has the same change pattern in groundwater and in soil,which further indicates that strontium in the study area comes from water-rock interactions.
