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关键词： elastic wedge   fluid-structure interaction   water entry slamming   wave-current action  

摘要： In structural strength design of ships, water entry slamming load receives great attention. Here, using computational fluid dynamics - finite element method (CFD-FEM) bidirectional coupling numerical method, the fluid-structure interaction problem of an elastic wedge under gravity entering water in different flow field environments was studied. Firstly, taking wedge slamming in still water as an example, Simulation results were compared with experimental ones to verify the eorreetness of CFD-FEM. Then, slamming forces, structural responses and flow field changes of elastic wedges with different water entry velocities and bottom oblique angles were analyzed when entering water in different flow field environments of still water, flow and waves. The results showed that water entry slamming of wedge in still water is consistent with experimental results of model, so the numerical Simulation has the reliability and feasibility;under action of uniform flow, when a wedge enters water, due to wall reflection of structure to incoming flow, the flow velocity near wedge is different from that far away from incoming flow to generate a pressure difference, bottom of wedge shifts to direction of incoming flow;when entering water at different wave positions, model equilibrium position is in direction of wave velocity, as the relative slamming velocity between wave and wedge increases, the generated slamming load is larger than that in still water, high stress zone is mainly concentrated at wedge bottom and weld position;the study results can provide a guidance for ship structure design and water entry slamming study. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： 基本医疗   全科医学   医院病床   住院服务   供给   利用  

摘要： 住院服务和非住院服务组成了国家和区域医疗服务系统。关注这两个子系统之间的关系是需要深入研究的问题。本文采用国内和国际的主要公开数据,初步分析医院住院服务提供和利用的状况和趋势及其影响因素,以及初级保健与住院服务的关系。结果显示中国住院率与人口老龄化程度和床位供应量呈正相关,且床位供应、利用率及全科医生资源同步增长。各省住院率存在明显差异。住院率高低难以用常用的社会经济、人口结构、卫生资源配置量等指标来解释,不过每百平方公里医院病床数与社会经济和人口指标以及其他资源结构有关。国际上的每千人口医院病床数在高收入国家呈下降趋势,在中收入国家呈增长趋势,在低收入国家维持低水平;住院率与人口老化程度、经济发展程度、医院治理政策等因素有关。世界各国已经意识到过度提供昂贵的住院服务会造成卫生系统不可持续性,均在致力于结构性的改革,将重点放在早期疾病的预防、巩固和加强初级卫生保健和基本医疗、改变医院的传统角色等。高收入国家已经通过各种措施降低了住院服务的供应和利用,中收入国家探讨住院服务的治理,低收入国家则探讨如何应对住院服务供应和利用不足的问题。因此,加强基本医疗服务不必然导致住院服务减少,不断发展基本医疗可以提高区域医疗服务的成本效益和公平性,优化住院服务资源的利用。对住院服务和基本医疗服务进行有效治理、建立和发展有规模和胜任的基本医疗服务、严格执行分级诊疗和守门人制度、针对特定病种和人群采取措施减少可避免住院等,有助于基本医疗促进更合理的住院服务提供和利用。

关键词： JavaScript课程   高职教育   职业需求   教学改革   校企合作  

摘要： 高职JavaScript课程是培养计算机及相关专业学生核心技能的重要组成部分,但现有教学内容难以完全满足企业需求,存在教学目标定位不清、课程内容与行业实践脱节等问题。文章通过分析当前高职JavaScript课程的定位、目标及教学内容与企业需求的匹配度,提出基于职业需求的教学方法改革思路,包括职业需求导向的教学目标设计、教学内容的优化与模块化设计,以及项目驱动式教学方法的引入等。结合任务导向与案例教学、多元化评价体系构建以及校企合作与行业资源整合,提出具体的教学改革实施策略,以期提升学生的职业素养和就业竞争力,促进课程的持续改进与优化。

关键词： 电磁感应   电容器   动态分析  

摘要： 电磁感应中含电容器电路简单模型在稍有不同条件时,其电路、动力学、能量的动态情况是有很大差异的,结果也不同。文中利用基本物理规律、物理思维方法以及数学方法,从电磁感应的简单含容电路模型入手,逐渐增加变化其条件,综合分析其各种情景下的电路情况、受力运动情况,并给出最终的结果。

关键词： 乡村振兴战略   老年人需求   农村社区   老年教育课程  

摘要： 乡村振兴战略的提出,不单推动农村经济发展,同时也对农村社会治理提出更高要求.在老龄化逐步加深的背景下,农村社区内老年人的教育需求日益凸显.农村老年教育既是提高个人素质的途径,也是增强乡村社区凝聚力,提升文化软实力的有效手段.从课程设计原则、课程在乡村振兴中的作用等角度,探讨符合老年人生理与心理特点的教育课程,并结合具体实践,提出有针对性的开发策略,旨在为农村社区提供可持续发展的教育支持.

关键词： Vortex shedding  

摘要： Three-dimensional direct numerical simulations of the vortex-induced vibration of a pin-pin supported near-wall elastic cylinder at a Reynolds number of Re = 300 were conducted using the immersed boundary method based on embedded iteration. The aspect ratio of the slender cylinder was L/D = 25, while the gap ratio G/D ranged from 0. 6 to 1.6. This corresponded to scenarios where the cylinder is fully covered by the boundary layer, partially submerged in the boundary layer, and completely outside the boundary layer, respectively. The results show that in the single-mode vibration regime, the vibration and the lift and drag coefficients of the cylinder at G/D = 0. 6 and G/D= 1. 1 are dominated by a single frequency. In contrast, at G/D= 1.6, two frequency components appear near the natural frequency. In the multi-mode vibration regime, the excitation and superposition of multiple modes cause the vibration and the lift and drag coefficients of the cylinder to exhibit a spatial-temporal distribution characterized by traveling waves. The merge of the upward-curling boundary layer and the wake vortices shed from the upper surface of the cylinder, together with the suppression of the vortices shed from the lower surface, leads to asymmetric vortex shedding. As the gap ratio increases, the suppression of vortex shedding weakens, and the wake sequentially exhibits the "IS", weak "2S", and "2S" vortex-shedding patterns. For multi-mode vibrations, the drag and lift spectra show the multi-frequency features while the streamwise and cross-flow vibrations are decoupled. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： Hopf bifurcation  

摘要： Wheel diameter difference can exacerbate the instability of bogie, and motor elastic frame Suspension structure can effectively improve its stability. Here, to investigate the relation between wheel diameter difference and lateral stability of motor elastic frame Suspension bogie, the wheel-rail nonlinear contact model and the lateral dynamic model of motor elastic frame Suspension bogie were established. Effects of wheel diameter difference and motor Suspension parameters on lateral stability of bogie were analyzed with the above models, and Hopf bifurcation characteristics of wheelsets under different wheel-rail contacts were studied. The study results showed that under in- phase wheel diameter difference, the stability of bogie System exhibits a trend of firstly increasing and then decreasing with increase in motor lateral shift frequency, and the optimal frequency is about 3 Hz;when Vibration frequency of motor is consistent with snake frequency of bogie and the former' s amplitude is lower than that of the latter, the Vibration reduction effect of motor frame Suspension is better, but the generation of wheel diameter difference can reduce this effect;when vehicle speed is too high and wheel diameter difference exceeds 1. 2 mm, wheel-rail can have wheel Hange contact to improve stability of bogie in short term, and exacerbate wheel-rail wear in long term;the larger the wheel diameter difference, the more the balance centerline of wheelset deviates from track centerline, and the more easily the wheelset System converts from subcritical Hopf bifurcation to supercritical Hopf bifurcation;the critical value of wheel diameter difference under in-phase wheel diameter difference condition is 0. 5 mm, and the critical value of wheel diameter difference of front wheelset is 1. 5 mm. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： 铵态氮   硝态氮   树木   氮吸收偏好  

摘要： 氮素(N)是树木生长发育过程所必需的营养元素,是树木合成核酸、蛋白质等的基本组成元素.目前关于树木对不同形态氮吸收偏好是依赖于物种特异性还是土壤氮可利用性仍存在不确定性.归纳整理树木对无机氮吸收的研究成果,分析生物属性(树种、树龄和菌根类型)和环境因素(土壤、水分、温度和光照)对树木氮吸收偏好的影响,研究结果表明,不同实验方法得出的树龄和菌根类型对树木氮吸收偏好的影响结果略有不同.根据现有研究存在的树木菌根类型与氮吸收偏好关系不确定等问题,提出加强树木根系形态与环境和生物因素的相关性分析,明确菌根类型对不同形态氮吸收偏好的影响,为生态系统物种共存、种间竞争和生态位互补等理论提供科学依据.