In functionally graded materials (FGM), the problem of interface stability caused by the volume deformation is commonly regarded as the key factor for its performance. Based on test results, in terms of finite element...In functionally graded materials (FGM), the problem of interface stability caused by the volume deformation is commonly regarded as the key factor for its performance. Based on test results, in terms of finite element method (FEM) this paper analyzed problems in the shrinkage of functionally graded material interface of shield concrete segment, which was designed and produced by the principle of functionally graded materials. In the analysis model, the total shrinkage of concrete was converted into the thermal shrinkage by means of the method of 'Equivalent Temperature Difference'. Consequently, the shrinkage stress of interface layer was calculated and compared with the bond strength of interface layer. The results indicated that the volume deformation of two-phase materials of functionally graded concrete (FGC) segment, which were the concrete cover and the concrete structure layer, showed better compatibility and the tension stress of interface layer, which was resulted from the shrinkage of concrete and calculated by ANSYS, was less than the bond strength of interface layer. Therefore, the interface stability of functionally graded concrete segment was good and the sliding deformation of interface layer would not generate.展开更多
The nonlinear analysis with an analytical approach on dynamic torsional buckling of stiffened functionally graded thin toroidal shell segments is investigated. The shell is reinforced by inside stiffeners and surround...The nonlinear analysis with an analytical approach on dynamic torsional buckling of stiffened functionally graded thin toroidal shell segments is investigated. The shell is reinforced by inside stiffeners and surrounded by elastic foundations in a thermal environment and under a time-dependent torsional load. The governing equations are derived based on the Donnell shell theory with the yon Karman geometrical nonlinearity, the Stein and McElman assumption, the smeared stiffeners technique, and the Galerkin method. A deflection function with three terms is chosen. The thermal parameters of the uniform temperature rise and nonlinear temperature conduction law are found in an explicit form. A closed-form expression for determining the static critical torsional load is obtained. A critical dynamic torsional load is found by the fourth-order Runge-Kutta method and the Budiansky-Roth criterion. The effects of stiffeners, foundations, material, and dimensional parameters on dynamic responses of shells are considered.展开更多
为突破传统人工阅片诊断的局限性,提高对宫颈癌变的筛查效率与准确率,提出一种利用改进后的视觉几何群网络(visual geometry group network,VGG-16)实现女性宫颈病变分级预测的方法,并对原始图像中女性宫颈部位进行感兴趣区域提取及病...为突破传统人工阅片诊断的局限性,提高对宫颈癌变的筛查效率与准确率,提出一种利用改进后的视觉几何群网络(visual geometry group network,VGG-16)实现女性宫颈病变分级预测的方法,并对原始图像中女性宫颈部位进行感兴趣区域提取及病变位置的定位与分割。在宫颈病变二分类的研究中,通过多次对比试验后,最终测得宫颈病变分级预测的准确率高达92.95%,与未经改进的方法相比,在时间复杂度与空间复杂度上都有明显的降低。试验表明:文中方法不仅能辅助放射科医生进行病变等级诊断,还可提高诊断的效率与准确率,在临床实践中具有重要意义。展开更多
文摘In functionally graded materials (FGM), the problem of interface stability caused by the volume deformation is commonly regarded as the key factor for its performance. Based on test results, in terms of finite element method (FEM) this paper analyzed problems in the shrinkage of functionally graded material interface of shield concrete segment, which was designed and produced by the principle of functionally graded materials. In the analysis model, the total shrinkage of concrete was converted into the thermal shrinkage by means of the method of 'Equivalent Temperature Difference'. Consequently, the shrinkage stress of interface layer was calculated and compared with the bond strength of interface layer. The results indicated that the volume deformation of two-phase materials of functionally graded concrete (FGC) segment, which were the concrete cover and the concrete structure layer, showed better compatibility and the tension stress of interface layer, which was resulted from the shrinkage of concrete and calculated by ANSYS, was less than the bond strength of interface layer. Therefore, the interface stability of functionally graded concrete segment was good and the sliding deformation of interface layer would not generate.
基金supported by the Vietnam National Foundation for Science and Technology Development(No.107.02-2015.11)
文摘The nonlinear analysis with an analytical approach on dynamic torsional buckling of stiffened functionally graded thin toroidal shell segments is investigated. The shell is reinforced by inside stiffeners and surrounded by elastic foundations in a thermal environment and under a time-dependent torsional load. The governing equations are derived based on the Donnell shell theory with the yon Karman geometrical nonlinearity, the Stein and McElman assumption, the smeared stiffeners technique, and the Galerkin method. A deflection function with three terms is chosen. The thermal parameters of the uniform temperature rise and nonlinear temperature conduction law are found in an explicit form. A closed-form expression for determining the static critical torsional load is obtained. A critical dynamic torsional load is found by the fourth-order Runge-Kutta method and the Budiansky-Roth criterion. The effects of stiffeners, foundations, material, and dimensional parameters on dynamic responses of shells are considered.
文摘为突破传统人工阅片诊断的局限性,提高对宫颈癌变的筛查效率与准确率,提出一种利用改进后的视觉几何群网络(visual geometry group network,VGG-16)实现女性宫颈病变分级预测的方法,并对原始图像中女性宫颈部位进行感兴趣区域提取及病变位置的定位与分割。在宫颈病变二分类的研究中,通过多次对比试验后,最终测得宫颈病变分级预测的准确率高达92.95%,与未经改进的方法相比,在时间复杂度与空间复杂度上都有明显的降低。试验表明:文中方法不仅能辅助放射科医生进行病变等级诊断,还可提高诊断的效率与准确率,在临床实践中具有重要意义。
