Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile...Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile organic compound(VOC)and nitrogen oxide(NO_(x))emission reduction ratios using the Weather Research and Forecasting-Comprehensive Air Quality Model Extensions model.The emission reduction of VOCs was beneficial for reducing fine particulate matter(PM_(2.5))concentration in January and ozone(O_(3))concentration in June.However,NO_(x)must be reduced by at least 48%and 70%to decrease PM_(2.5)and O_(3)concentrations,respectively,when VOCs are not reduced.The responses of PM_(2.5)and O_(3)concentrations to emission reductions from different sources were also evaluated.The reduction in VOC emissions from different sources decreased the PM_(2.5)concentration in January,and O_(3)concertation in June,while NO_(x)reduction resulted in an increase.Controlling VOC emissions from industry has a positive effect on improving local PM_(2.5)and O_(3),while the emission reductions of NO_(x)from transportation and industry are not conducive to reducing PM_(2.5)and O_(3)concentrations.The synergistic emission reduction pathways for NO_(x)and VOCs during PM_(2.5)and O_(3)combined pollution were also analyzed.The VOC and NO_(x)emission reductions were beneficial for reducing the comprehensive Air Quality Index(sAQI)values.When the NO_(x)emission reduction was large,the sAQI improvement gradually exceeded that of VOCs.A collaborative optimization path should be adopted that focuses on controlling VOCs first,and further control of combined pollution should depend on the deep reduction of NO_(x).展开更多
Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of bette...Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically展开更多
In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the ti...In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the time-dependent properties of a variety of viscoelastic materials, is proposed. Numerical examples are performed to illustrate the sensitivity of the model to material parameters.展开更多
Direct numerical simulations are carried out with different disturbance forms introduced into the inlet of a flat plate boundary layer with the Mach number 4.5. According to the biorthogonal eigenfunction system of th...Direct numerical simulations are carried out with different disturbance forms introduced into the inlet of a flat plate boundary layer with the Mach number 4.5. According to the biorthogonal eigenfunction system of the linearized Navier-Stokes equations and the adjoint equations, the decomposition of the direct numerical simulation results into the discrete normal mode is easily realized. The decomposition coefficients can be solved by doing the inner product between the numerical results and the eigenfunctions of the adjoint equations. For the quadratic polynomial eigenvalue problem, the inner product operator is given in a simple form, and it is extended to an Nth-degree polynomial eigenvalue problem. The examples illustrate that the simplified mode decomposition is available to analyze direct numerical simulation results.展开更多
By the nonlinear finite element analysis （FEA） method, the mechanical properties of the steel fiber reinforced concrete （SFRC） deep beams were discussed in terms of the crack load and ultimate bearing capacity. In...By the nonlinear finite element analysis （FEA） method, the mechanical properties of the steel fiber reinforced concrete （SFRC） deep beams were discussed in terms of the crack load and ultimate bearing capacity. In the simulation process, the ANSYS parametric design language （APDL） was used to set up the finite element model; the model of bond stress-slip relationship between steel bar and concrete was established. The nonlinear FEA results and test results demonstrated that the steel fiber can not only significantly improve the cracking load and ultimate bearing capacity of the concrete but also repress the development of the cracks. Meanwhile, good agreement was found between the experimental data and FEA results, if the unit type, the parameter model and the failure criterion are selected reasonably.展开更多
基金funded by the Shandong Postdoctoral Science Foundation(No.SDCX-ZG-202303008).
文摘Exploring the nonlinear relationship between air pollution and precursor emissions in Qingdao,eastern China is crucial for improving air quality.We simulated 32 emission reduction scenarios based on different volatile organic compound(VOC)and nitrogen oxide(NO_(x))emission reduction ratios using the Weather Research and Forecasting-Comprehensive Air Quality Model Extensions model.The emission reduction of VOCs was beneficial for reducing fine particulate matter(PM_(2.5))concentration in January and ozone(O_(3))concentration in June.However,NO_(x)must be reduced by at least 48%and 70%to decrease PM_(2.5)and O_(3)concentrations,respectively,when VOCs are not reduced.The responses of PM_(2.5)and O_(3)concentrations to emission reductions from different sources were also evaluated.The reduction in VOC emissions from different sources decreased the PM_(2.5)concentration in January,and O_(3)concertation in June,while NO_(x)reduction resulted in an increase.Controlling VOC emissions from industry has a positive effect on improving local PM_(2.5)and O_(3),while the emission reductions of NO_(x)from transportation and industry are not conducive to reducing PM_(2.5)and O_(3)concentrations.The synergistic emission reduction pathways for NO_(x)and VOCs during PM_(2.5)and O_(3)combined pollution were also analyzed.The VOC and NO_(x)emission reductions were beneficial for reducing the comprehensive Air Quality Index(sAQI)values.When the NO_(x)emission reduction was large,the sAQI improvement gradually exceeded that of VOCs.A collaborative optimization path should be adopted that focuses on controlling VOCs first,and further control of combined pollution should depend on the deep reduction of NO_(x).
基金supported by The HongKong Polytechnic University Research Grants(No.1-BB81)grants from National Natural Science Foundation of China,Nos.10872078 and 10832012
文摘Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically
文摘In this paper, a simple nonlinear Maxwell model consisting of a nonlinear spring connected in series with a nonlinear dashpot obeying a power-law with constant material parameters, for representing successfully the time-dependent properties of a variety of viscoelastic materials, is proposed. Numerical examples are performed to illustrate the sensitivity of the model to material parameters.
基金supported by the National Natural Science Foundation of China(Nos.1133200711202147+2 种基金and 9216111)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120032120007)the Open Fund from State Key Laboratory of Aerodynamics(Nos.SKLA201201 and SKLA201301)
文摘Direct numerical simulations are carried out with different disturbance forms introduced into the inlet of a flat plate boundary layer with the Mach number 4.5. According to the biorthogonal eigenfunction system of the linearized Navier-Stokes equations and the adjoint equations, the decomposition of the direct numerical simulation results into the discrete normal mode is easily realized. The decomposition coefficients can be solved by doing the inner product between the numerical results and the eigenfunctions of the adjoint equations. For the quadratic polynomial eigenvalue problem, the inner product operator is given in a simple form, and it is extended to an Nth-degree polynomial eigenvalue problem. The examples illustrate that the simplified mode decomposition is available to analyze direct numerical simulation results.
基金the Science Foundation for Young Scientists of Hubei Province Educational Committee of China (B200514003)
文摘By the nonlinear finite element analysis （FEA） method, the mechanical properties of the steel fiber reinforced concrete （SFRC） deep beams were discussed in terms of the crack load and ultimate bearing capacity. In the simulation process, the ANSYS parametric design language （APDL） was used to set up the finite element model; the model of bond stress-slip relationship between steel bar and concrete was established. The nonlinear FEA results and test results demonstrated that the steel fiber can not only significantly improve the cracking load and ultimate bearing capacity of the concrete but also repress the development of the cracks. Meanwhile, good agreement was found between the experimental data and FEA results, if the unit type, the parameter model and the failure criterion are selected reasonably.
