For multi-cell curve box girder, the finite strip governing equation was derived on the basis of Novozhilov theory and orthogonal property of harmonious function series. Dynamic Bayesian error function of mechanical p...For multi-cell curve box girder, the finite strip governing equation was derived on the basis of Novozhilov theory and orthogonal property of harmonious function series. Dynamic Bayesian error function of mechanical parameters of multi-cell curve box girder was achieved with Bayesian statistical theory. The corresponding formulas of dynamic Bayesian expectation and variance were obtained. After the one-dimensional optimization search method for the automatic determination of step length of the mechanical parameter was put forward, the optimization identification calculative formulas were also obtained by adopting conjugate gradient method. Then the steps of dynamic Bayesian identification of mechanical parameters of multi-cell curve box girder were stated in detail. Through analysis of a classic example, the dynamic Bayesian identification processes of mechanical parameters are steadily convergent to the true values, which proves that dynamic Bayesian theory and conjugate gradient theory are suitable for the identification calculation and the compiled procedure is correct. It is of significance that the foreknown information of mechanical parameters should be set with reliable practical engineering experiences instead of arbitrary selection.展开更多
Large-scale ocean‒atmosphere circulations(LOACs)have a pronounced effect on the near-surface wind speed(NSWS).In this study,we discussed the contributions of zonal and meridional flows to NSWS changes and identify the...Large-scale ocean‒atmosphere circulations(LOACs)have a pronounced effect on the near-surface wind speed(NSWS).In this study,we discussed the contributions of zonal and meridional flows to NSWS changes and identify the possible association between the Northern Hemisphere Annular Mode(NAM)and the NSWS changes over eastern China from 1979 to 2017.Results show that the reduction in NSWS over eastern China was mainly dominated by the weakening of the zonal wind component.NAM has a considerable effect on the NSWS over eastern China.When the NAM exhibits positive phases,the zonal-mean westerly weakens at low-to-mid-latitudes(10°-40°N).Meanwhile,descending flows prevail near 40°N,and ascending flows persist near 65°N in the troposphere.In the lower troposphere,there are northerly anomalies at low-to-mid-latitudes and southerly anomalies at mid-to-high latitudes(40°-70°N).The anomalous meridional flows transport heat from low to high latitudes and weaken the north‒south air temperature gradient.The decreased air temperature gradient over East Asia reduces the pressure gradient near the surface,decreasing NSWS in eastern China.NAM variations could dominate(32.0±15.8)%of the changes in the annual mean NSWS.Nevertheless,the contribution of NAM to the interannual changes of the zonal component in NSWS could reach(45.0±12.9)%.展开更多
The purpose of this paper is to investigate the bending,buckling,vibration analyses of microcomposite circular-annular sandwich plate with CNT reinforced composite facesheets under hydro-thermo-magneto-mechanical load...The purpose of this paper is to investigate the bending,buckling,vibration analyses of microcomposite circular-annular sandwich plate with CNT reinforced composite facesheets under hydro-thermo-magneto-mechanical loadings are presented using first order shear deformation theory(FSDT)and modified strain gradient theory(MSGT)that includes three material length scale parameters.Also,an isotropic homogeneous core is considered for microcomposite circular-annular sandwich plate.The generalized rule of mixture is employed to predict mechanical,moisture and thermal properties ofmicrocomposite sandwich plate.By using Hamilton’s principle,governing equations are solved by differential quadrature method(DQM)for a circular annular sandwich plate.The predicted results are validated by carrying out the comparison studies for the FGM plates by modified couple stress theory(MCST).The obtained results are given to indicate the influence of the material length scale parameter,core-to-facesheet thickness ratios,magnetic effect,thermal andmoisture effects on the dimensionless deflection,critical buckling load,and natural frequency of microcomposite circular sandwich plate.The results can be employed in solid-state physics,materials science,nano-electronics,and nano electro-mechanical devices such as microactuators,and microsensor.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10772078 and 11072108)the Transportation Science Foundation of Jiangsu Province (Grant No. 09Y012)
文摘For multi-cell curve box girder, the finite strip governing equation was derived on the basis of Novozhilov theory and orthogonal property of harmonious function series. Dynamic Bayesian error function of mechanical parameters of multi-cell curve box girder was achieved with Bayesian statistical theory. The corresponding formulas of dynamic Bayesian expectation and variance were obtained. After the one-dimensional optimization search method for the automatic determination of step length of the mechanical parameter was put forward, the optimization identification calculative formulas were also obtained by adopting conjugate gradient method. Then the steps of dynamic Bayesian identification of mechanical parameters of multi-cell curve box girder were stated in detail. Through analysis of a classic example, the dynamic Bayesian identification processes of mechanical parameters are steadily convergent to the true values, which proves that dynamic Bayesian theory and conjugate gradient theory are suitable for the identification calculation and the compiled procedure is correct. It is of significance that the foreknown information of mechanical parameters should be set with reliable practical engineering experiences instead of arbitrary selection.
基金National Key Research and Development Program of China(2018YFA0606004)Natural Science Foundation of China(42005023,41875178,41865001)+1 种基金Swedish Formas(2019-00509 and 2017-01408)VR(2021-02163 and 2019-03954).
文摘Large-scale ocean‒atmosphere circulations(LOACs)have a pronounced effect on the near-surface wind speed(NSWS).In this study,we discussed the contributions of zonal and meridional flows to NSWS changes and identify the possible association between the Northern Hemisphere Annular Mode(NAM)and the NSWS changes over eastern China from 1979 to 2017.Results show that the reduction in NSWS over eastern China was mainly dominated by the weakening of the zonal wind component.NAM has a considerable effect on the NSWS over eastern China.When the NAM exhibits positive phases,the zonal-mean westerly weakens at low-to-mid-latitudes(10°-40°N).Meanwhile,descending flows prevail near 40°N,and ascending flows persist near 65°N in the troposphere.In the lower troposphere,there are northerly anomalies at low-to-mid-latitudes and southerly anomalies at mid-to-high latitudes(40°-70°N).The anomalous meridional flows transport heat from low to high latitudes and weaken the north‒south air temperature gradient.The decreased air temperature gradient over East Asia reduces the pressure gradient near the surface,decreasing NSWS in eastern China.NAM variations could dominate(32.0±15.8)%of the changes in the annual mean NSWS.Nevertheless,the contribution of NAM to the interannual changes of the zonal component in NSWS could reach(45.0±12.9)%.
基金This work was supported by the University of Kashan[574602/15].
文摘The purpose of this paper is to investigate the bending,buckling,vibration analyses of microcomposite circular-annular sandwich plate with CNT reinforced composite facesheets under hydro-thermo-magneto-mechanical loadings are presented using first order shear deformation theory(FSDT)and modified strain gradient theory(MSGT)that includes three material length scale parameters.Also,an isotropic homogeneous core is considered for microcomposite circular-annular sandwich plate.The generalized rule of mixture is employed to predict mechanical,moisture and thermal properties ofmicrocomposite sandwich plate.By using Hamilton’s principle,governing equations are solved by differential quadrature method(DQM)for a circular annular sandwich plate.The predicted results are validated by carrying out the comparison studies for the FGM plates by modified couple stress theory(MCST).The obtained results are given to indicate the influence of the material length scale parameter,core-to-facesheet thickness ratios,magnetic effect,thermal andmoisture effects on the dimensionless deflection,critical buckling load,and natural frequency of microcomposite circular sandwich plate.The results can be employed in solid-state physics,materials science,nano-electronics,and nano electro-mechanical devices such as microactuators,and microsensor.
