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关键词： 负摩阻力   群桩效应系数   模型试验   群桩   斜桩   隔离桩  

摘要： 边载作用会导致群桩基础产生负摩阻力,可能危及桩基及上部结构,了解不同形式群桩的边载负摩阻力至关重要.设计了边载作用下单桩、直桩群桩(3×2)、斜直群桩(3×2)以及叉桩的室内模型试验,测量了桩身轴力和弯矩,讨论了桩身负摩阻力特性和边载负摩阻力群桩效应.结果表明,相较单直桩,单斜桩最大弯矩和平均负摩阻力分别增大6.7%和8.2%;布置隔离桩后,单桩平均负摩阻力减小接近5%,直桩群桩的负摩阻力群桩效应系数减小10.4%~23.5%;与直桩群桩相比,斜直群桩的前排角桩、边桩的负摩阻力群桩效应系数分别增大6.98%和9.59%,后排基桩承载差异相对较小;叉桩、半叉桩的负摩阻力群桩效应系数分别为0.98~1.12和0.94~1.08.边载作用下叉桩结构顶部沉降小、负摩阻力作用明显,建议采用必要的消减措施.

关键词： 家庭教育指导服务   家校社协同育人   IAD框架   SES框架  

摘要： 我国家庭教育指导服务已形成多元主体协同的供给模式,但仍存在主体权责划分不清、区域供给不协调、服务内容同质化、监督评价机制缺乏等困境。基于“IAD+SES”框架的家庭教育指导服务网络化供给模式是一种基于主体间合作伙伴关系实现资源共享、区域联动的创新模式,能够动态分析家庭教育指导服务的供给过程,识别外部环境、行动舞台、结果产出等层次的关键要素,探究要素间的互动关系,动态调整供给网络策略,可以有效解决上述困境。基于“IAD+SES”框架,家庭教育指导服务各主体应加强子网络区域特色建设,保障监督评价动态多元化,创立家庭教育责任联盟,为家庭教育指导服务的高质量发展提供实践支持。

关键词： 中职教育   技能学业水平考试   职业能力评价   产教融合  

摘要： 在“中国制造2025”战略和数字经济快速发展的背景下,中职学业水平考试亟须转向以考查职业能力和核心素养为核心的评价体系。纵观中职技能学考的发展历程,传统的中职学考模式面临诸如师资建设与学考高标准要求的契合度不足、学考方式对岗位职业能力的提升效度不够、学考内容与地区产业发展需求之间匹配度不高等现实挑战。为精准对接人才培养与市场需求,推动职业教育从“知识传授”向“能力培养”转型,需重点围绕构建教师发展共同体、创新智能化考核模式、深化产教融合等路径进行改革创新。

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： Helicopters  

摘要： Aiming at the problem of insufficient consideration of helicopter/engine coupling relationship in the traditional overall parameter design process of turboshaft engines and the lack of boundary restrictions on the feasible region of alternative design parameters，this paper proposes a method for optimizing the overall parameters of turboshaft engines based on the requirements of helicopter flight missions， and reasonably limits the feasible region of design parameter optimization according to the development of turboshaft engines. The method consists of four modules: constraint analysis，task analysis，parameter cycle calculation and optimization iteration. The optimization iteration module involves dynamic adjustment of design parameters，which makes the designed engine more matched with the task requirements. Firstly，the basic principles of the above four modules are derived. Then，based on the given helicopter flight mission profile，the proposed design method is verified by an example. Finally，the results are compared with other design methods for the same flight mission. The research shows that the proposed feasible region boundary of design parameters can reasonably limit the selection range of design parameters and can be used as a basis for the selection of design parameters. The proposed optimization design method of the overall parameters of the turboshaft engine makes up for the shortcomings of other overall design methods of the turboshaft engine，such as the design parameters are not involved in the iterative update and the lack of consideration of the coupling relationship between the helicopter/turboshaft engine performance. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： 消费需求波动   供应链韧性   影响因素   风险对冲策略  

摘要： 在全球经济不确定性攀升、消费市场加速变革背景下,消费需求波动变得常态化,给供应链韧性带来了持续的冲击。在此背景下,研究供应链韧性影响因素及对冲策略,对保障企业稳定运营、提升抗风险能力具有重要现实意义。基于此,本文从消费需求波动的特征与传导路径、供应链韧性的内涵与评价维度、消费需求波动与供应链韧性的相互作用关系三个维度,探究消费需求波动对供应链韧性的影响机制;分析了消费需求波动下供应链韧性的关键影响因素,主要包括内部因素和外部因素,如生产计划的拟定、库存管理、市场环境相关因素等。文章最后提出了消费需求波动下供应链韧性的风险对冲策略,如优化供应链网络结构、加强供应链协同管理、提升供应链信息技术应用水平、建立供应链风险预警与应急机制,以期为增强企业供应链韧性提供理论指导与实践借鉴。