教育元宇宙:教育复杂系统的混合物理模型

元宇宙作为前沿理念聚焦与信息技术融合的载体,可为教育科学体系变革提供支撑。在梳理教育元宇宙现有研究成果的基础上,透过复杂性科学视野审视教育元宇宙。研究认为:教育元宇宙可理解为教育复杂系统的混合物理模型,利用教育复杂系统表征“教育”可以统括教育涉及的一切特性,是认识论层面的升华;通过混合物理模型刻画“元宇宙”能够深刻把握“链上虚拟世界”的本质,是方法论层面的落地。教育元宇宙的架构主要包括教育复杂系统框架和混合物理模型框架:前者的建立涉及复杂系统的结构、功能及机制,其功能维度的需求决定结构维度的设计,通过逻辑推演形成理论层面的概念模型;后者涵盖主观、客观及现实三部分,借助信息技术整合为实践层面的数值模型,其结构维度的计算引发功能维度的演化。教育元宇宙除在深度沉浸、具身交互、时空跨越、虚实融生等方面的教育赋能外,其深层应用在于探明教育复杂系统演化的规律、发展优化和调控教育系统的方法以及建立可解释的教育评价体系。

基于深度学习的高阶思维培养模型研究

近年来高阶思维在基础教育改革中受到高度重视,而深度学习作为信息时代教学变革的必然选择,能够为学生高阶思维的培养提供支持。为此,文章首先明确了高阶思维的内涵,同时基于复杂系统理论将深度学习内涵界定为学习科学视域下的最优整合,并探讨了高阶思维和深度学习的关系。随后,文章结合对影响因素的梳理,分别提出了高阶思维的生成机制和深度学习的生成机制,并从宏观、中观、微观三个层面剖析了这两个生成机制的关系。最后,文章构建了基于深度学习的高阶思维培养模型,包括情境问题的创设、拓展方向的确立、最优整合的趋近、心理机能的升华等四个模块。此模型具有系统性、整体性特征,有助于在基础教育课程中促进学生的深度学习,从而更好地发展学生的高阶思维。

Test and numerical investigations on static and dynamic characteristics of extra-wide concrete self-anchored suspension bridge under vehicle loads

The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite element simulations, the static deformations of different components, stress increments and distributions of the girder, as well as the vibration characteristics and damping ratio of the Hunan Road Bridge were analyzed, which is the widest self-anchored suspension bridge in China at present. The dynamic responses were calculated using the Newmark-β integration method assisted by the simulation models of bridge and vehicles, the influences on the dynamic impact coefficient(DIC) brought by the vehicle parameters, girder width, eccentricity travel and deck flatness were also researched. The spatial effect of the girder is obvious due to the extra width, which performs as the stress increments distribute unevenly along the transverse direction, and the girder deflections and stress increments of the upper plate change as a "V" and "M" shape respectively under the symmetrical vehicle loads affected by the shear lag effect, cross slope and local effect of the wheels, the maximum of stress increments are located in the junctions with the inner webs. The obvious girder torsional deformation and the apparent unevenness of the hanger forces between the two cable planes under the eccentric vehicle loads, together with the mode shapes such as the girder transverse bending and torsion which appear relatively earlier, all reflect the weakened torsional rigidity of the extra-wide girder. The transverse displacements of towers are more obvious than the longitudinal ones. As for the influences on the DIC, the static effect of the heavier vehicles plays a major role when pass through with a higher speed and the changes of vehicle suspension stiffness generate greater impacts than the suspension damp. The values of DIC in the vehicle-running side during the eccentric travel, affected by the restricts from the static effects of the eccentric moving trucks, are significantly smaller than the vehicle-free side, the increase in the road roughness is the most sensitive one among the above influential factors. The results could provide references for the design, static and dynamic response analysis of the similar extra-wide suspension bridges.

Health monitoring and comparative analysis of time-dependent effect using different prediction models for self-anchored suspension bridge with extra-wide concrete girder

The structural health status of Hunan Road Bridge during its two-year service period from April 2015 to April 2017 was studied based on monitored data.The Hunan Road Bridge is the widest concrete self-anchored suspension bridge in China at present.Its structural changes and safety were evaluated using the health monitoring data,which included deformations,detailed stresses,and vibration characteristics.The influences of the single and dual effects comprising the ambient temperature changes and concrete shrinkage and creep(S&C)were analyzed based on the measured data.The ANSYS beam finite element model was established and validated by the measured bridge completion state.The comparative analyses of the prediction results of long-term concrete S&C effects were conducted using CEB-FIP 90 and B3 prediction models.The age-adjusted effective modulus method was adopted to simulate the aging behavior of concrete.Prestress relaxation was considered in the stepwise calculation.The results show that the transverse deviations of the towers are noteworthy.The spatial effect of the extra-wide girder is significant,as the compressive stress variations at the girder were uneven along the transverse direction.General increase and decrease in the girder compressive stresses were caused by seasonal ambient warming and cooling,respectively.The temperature gradient effects in the main girder were significant.Comparisons with the measured data showed that more accurate prediction results were obtained with the B3 prediction model,which can consider the concrete material parameters,than with the CEB-FIP 90 model.Significant deflection of the midspan girder in the middle region will be caused by the deviations of the cable anchoring positions at the girder ends and tower tops toward the midspan due to concrete S&C.The increase in the compressive stresses at the top plate and decrease in the stresses at the bottom plate at the middle midspan will be significant.The pre-deviations of the towers toward the sidespan and pre-lift of the midspan girder can reduce the adverse influences of concrete S&C on the structural health of the self-anchored suspension bridge with extra-wide concrete girder.