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关键词： Micropolar elasticity   Sliding friction   Size effect   Indentation   Singular integral equation  

摘要： In this study, the sliding friction contact problems associated with the indentation of an elastic half-plane by rigid cylindrical and flat punches were investigated within the context of the micropolar theory. The micropolar theory of elasticity introduces the characteristic material length and the dimensionless coupling number to describe the size effect. Coulomb's friction law is satisfied by a punch when it is subjected to both normal and tangential forces. Using the Fourier integral transformation technique, these mixed-boundary value problems were reduced to singular integral equations of the second kind in which the unknown quantity is the contact stress on the contact surface. The collocation method was utilized to solve the integral equations numerically. An extensive parametric study was conducted to investigate the effects of the friction coefficient, the characteristic material length, and the dimensionless coupling number on the normal and in-plane stresses. The results show that the contact stress predicted by the micropolar theory differs significantly from those predicted by the couple stress theory and the classical elasticity theory.

关键词： Volumetric locking   Mixed displacement-pressure formulation   EFG method   Irregular pressure node distribution   Hyperelastic materials  

摘要： Rubber-like materials that are commonly used in structural applications are modelled using hyperelastic material models. Most of the hyperelastic materials are nearly incompressible, which poses challenges, i.e., volumetric locking during numerical modelling. There exist many formulations in the context of the finite element method, among which the mixed displacement-pressure formulation is robust. However, such a displacement-pressure formulation is less explored in meshfree methods, which mitigates the problem associated with mesh distortion during large deformation. This work addresses this issue of alleviating volumetric locking in the element-free Galerkin method (EFGM), which is one of the popular meshfree methods. A two-field mixed variational formulation using the perturbed Lagrangian approach within the EFGM framework is proposed for modelling nearly incompressible hyperelastic material models, such as Neo-Hookean and Mooney-Rivlin. Taking advantage of the meshless nature of the EFGM, this work introduces a unique approach by randomly distributing pressure nodes across the geometry, following specific guidelines. A wide spectrum of problems involving bending, tension, compression, and contact is solved using two approaches of the proposed displacement-pressure node formulation involving regular and irregular pressure node distribution. It is observed that both approaches give accurate results compared to the reference results, though the latter offers flexibility in the pressure nodal distribution. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)-(sic)(sic)(sic)(sic)(sic)(si

关键词： 幼小衔接   科学教育   儿童发展   教学方法  

摘要： 幼小衔接阶段是儿童教育中的重要环节,这一时期的教育质量对儿童的认知发展以及科学的生态意识培养具有深远影响。科学教育作为这一阶段的重要组成部分,其有效性直接关系到儿童未来学习的基础和对科学现象的理解能力。尽管已有多项研究关注幼小衔接中的科学教育,但在教学方法、课程设计和教师专业发展等方面仍存在诸多挑战和不足。本文旨在综合分析幼小衔接中的科学教育现状,探讨有效的教学方法及其对儿童发展的影响,以期为教师提供实践指导,促进儿童在这一重要阶段的全面发展,以提升他们的科学素养和创新能力。

关键词： 多期试点   社会政策创新   弹性调适   政策试点   老龄社会治理  

摘要： 随着全球化、城市化与数字化的推进,社会问题的复杂性特征日益凸显,传统政策制定模式难以应对新出现的治理议题。多期试点在政策制定中凝聚多方共识,灵活调适方案,是提升社会政策创新有效性的重要路径。本文通过构建“多期试点—政策调适”分析框架,解析了四种政策调适模式:试点集成—政策叠加、试点微调—政策更新、试点重置—政策转型、试点失灵—政策悬停。通过对老龄社会治理领域四项改革的比较研究,发现多期试点为社会政策创新的适应性调整提供了弹性空间:当试点结果有效时,政府系统启动正反馈循环,采取政策强化或优化机制,加速社会政策的创新迭代。当首轮试点失效时,负反馈循环启动,相关部门延长试点时限,重塑目标,重置方案。本研究提炼了社会政策创新的生成机理,在理论层面丰富了政策过程理论,为理解中国场景下复杂社会问题的治理路径提供新视角;在实践层面为政府优化试点机制、提高政策效能提供参考。

关键词： 高职院校   思想动态   教师队伍建设  

摘要： 随着社会经济快速发展及多元化环境变化,高职院校教师队伍建设面临诸多挑战。为加强高职院校教师队伍建设,围绕职业认同、职业倦怠、职业困境、职业发展、组织认同等五个方面,组织开展教师思想动态调查。通过分析思想动态调查结果,提出加强组织建设、建立激励机制、完善培训体系、优化管理模式、关心教师需求等对策建议,希望能对高职院校教师队伍建设提供有益的借鉴与参考。

关键词： 森林防火   认知水平   科普教育   问卷调查  

摘要： 【目的】森林火灾是生态文明建设成果和森林资源安全的最大威胁,是人类社会面临的共同挑战。小学生对森林火灾的认知和行为习惯正在形成,学校是小学生获得森林防火知识和技能的主要途径。【方法】基于北京市2400名小学生的问卷调研数据,分析不同区域的低年级和高年级小学生森林防火认知现状和科普需求的群体差异。【结果】北京市小学生对森林防火知识的认知水平整体较高,但认知普及仍不够全面,并在不同年级和区域之间存在差异。【结论】未来,森林防火科普教育工作要具有更强的针对性和多元化特点,充分结合实践活动来丰富教学内容和创新课堂教学形式,全方位、多层次地提高森林防火的科普力度和质量,让小学生群体成为保护森林、传承生态文明的有生力量,为可持续发展保驾护航。

关键词： 提振消费   经济高质量发展   品牌融合   花炮故里  

摘要： 原标题:做好品牌融合文章全面激发消费活力大力。提振消费是中央经济工作会议和今年《政府工作报告》的重点任务之首,也是推动高质量发展的重要引擎。萍乡将坚持把提振消费放在突出位置,以“工运摇篮”“花炮故里”“户外天堂”“中国辣都”四张城市名片为主抓手,着力做好品牌融合文章,激发消费新动能,为推动萍乡经济高质量发展注入强劲动力。

关键词： 大国工匠   技术技能人才   国家产业升级   职业本科  

摘要： 随着社会对技术技能人才的需求增加,职业教育正在崛起。职业本科教育作为职业教育的新阶段,其发展不仅关系到人才培养的质量,更关乎国家产业升级和经济增长。从2014年国家首次提出“探索发展本科层次职业教育”。