乡村振兴战略中的农村公共体育服务有效供给

乡村振兴战略自党的十九大报告提出后,成为“三农”事业发展的顶层设计,并以产业兴旺、生态宜居、乡风文明、治理有效、生活富裕为总要求。在该战略背景下,我国农村公共体育服务虽已取..

Anti-tension technology of slipway in long-stroke horizontal vibration table

为了解决长行程水平向振动台中管线对滑台牵拉引起的输出波形失真问题,提出一种带动管线跟踪滑台同步运动的随动装置设计方法.建立管线牵拉力作用下的水平向振动台机电耦合动力学模型,计算管线牵拉力对振动台输出波形失真度的影响;设计一种基于光栅尺的滑台随动装置,带动随动平台与滑台做同步运动,滑台上的管线经随动平台后引出,此时管线的牵拉力直接作用在随动平台上,而滑台上受到的牵拉力趋于零.试验结果表明,通过增设滑台随动装置,水平向振动台在做超低频大行程振动时的输出波形失真度得到极大的改善.In order to solve the problem of output waveform distortion due to the pipes and wires' tension in a long-stroke horizontal vibration table,a follow-up-gear design technology was put forward which drove the pipes and wires to move synchronously with the slipway.The electromechanical coupling kinetic model of a horizontal vibration table was analyzed considering the tension of pipes and wires in it,and the influences of tension forces of the pipes and wires on the output waveform distortion of the horizontal vibration table was calculated.A follow-up gear for the slipway was developed based on a precise linear encoder,and drove a following table moving synchronously with the slipway.And the pipes and wires on the slipway were led out through the following table,on which the tension forces directly acted,but the tension force on the slipway drove to zero.The experimental results indicate that the output waveform distortion improves greatly after adding the follow-up gear when the horizontal vibration table works in long-stroke and ultra-low-frequency motion.新世纪优秀人才支持计划资助项目(NCET-08-0494);浙江省“钱江人才计划”资助项目(2009R10026);浙江省重点科技创新团队建设资助项目(2009R50008

Eliminating residual stress in 45 steel quenching specimens by electrical pulse

为了研究电脉冲消除金属材料内部残余应力的效果,通过储能电容器放电产生高能电脉冲,对淬火后的45优质碳素结构钢冷轧薄板件进行放电处理,采用小孔法测定电脉冲处理前后试样内残余应力的变化规律.用于电脉冲处理的脉冲电流为指数衰减的振荡波形,同时满足第一个主峰的电流密度为12.2kA/MM2,单次处理的振荡脉冲持续时间小于0.8MS.试验结果表明,经过电脉冲处理后,45钢淬火件中2个主方向残余应力的幅值均出现较为显著的降低,且两者都出现均化效果.In order to investigate the effect of electrical pulse on eliminating residual stress within metallic material,high-energy electrical pulse was generated by discharging with energy-storage capacitors,and was adopted to treat quenching cold-rolled sheet specimens that were made of 45 high-quality carbon structural steel,and the hole-drilling method was taken to determine the change rule of the residual stress within the specimens before and after electropulse treatment.The pulse current used for electropulse treatment had oscillating waveshape with exponential damping,whose first peak of the current density was 12.2 kA/mm2 and oscillating pulse duration of single treatment was less than 0.8ms.The experimental results show that the amplitude of residual stresses in the two principal directions of 45 steel quenching specimens decrease much more significantly after electropulsing treatment and both of them are homogenized.国家自然科学基金资助项目(50675200);中央高校基本科研业务费专项资金资助项目(2009QNA4002);浙江省重点科技创新团队建设项目资助项目(2009R50008

非光滑叶片对叶栅气动特性影响的实验研究

在低速平面叶栅风洞中对光滑叶片及3种非光滑叶片进行了实验研究,分析了非光滑叶片对叶栅出口流动特性的影响. 实验结果表明,采用非光滑叶片改变了叶栅出口旋涡结构及流动分布,使叶栅出口的流场趋于均匀,叶片可以承受更大的负荷

非光滑叶片对叶栅出口流向涡系的影响

在低速平面叶栅风洞中对光滑叶片及非光滑叶片叶栅进行了实验研究,在叶栅出口进行了详细的测量,通过测量结果对比分析,探讨非光滑叶片对叶栅流向涡系的影响。实验结果表明,与光滑叶片相比,非光滑叶片对叶栅出口流向涡系中,通道涡在节距方向上移向叶栅通道中心处,强度几乎不变,尾缘涡发生展向扩展并分裂,强度明显减弱

非光滑叶片对叶栅出口流向涡系的影响

在低速平面叶栅风洞中对光滑叶片及非光滑叶片叶栅进行了实验研究,在叶栅出口进行了详细的测量,通过测量结果对比分析,探讨非光滑叶片对叶栅流向涡系的影响。实验结果表明,与光滑叶片相比,非光滑叶片对叶栅出口流向涡系中,通道涡在节距方向上移向叶栅通道中心处,强度几乎不变,尾缘涡发生展向扩展并分裂,强度明显减弱

Measurement of Non-uniform Residual Stresses by Incremental Hole-Drilling Method

针对传统的小孔法只能测量试件内沿深度方向均匀分布的残余应力,采用逐层钻孔的小孔法测量试件中的非均匀残余应力,通过有限元法标定计算校准系数矩阵,构建了一种实用的非均匀应力测试技术。首先,用AnSyS软件构造试件和应变花粘贴的三维有限元模型,采用分层加载的办法实现各层校准系数的仿真计算,标定计算出钻孔深度达到H=0.5d使应力完全释放时,用5步逐层钻孔法构造5层不均匀应力所需的校准系数矩阵;然后,利用标定出的校准系数矩阵,采用5步逐层钻孔的实验方法,测量构建Cr12MOV淬火件的5层非均匀残余应力,并与传统的小孔法进行测试比对。结果表明:用有限元仿真的方法可以模拟试件中的非均匀残余应力场,用于标定计算测量所需的校准系数矩阵;通过5步逐层钻孔实验测量,可以构建出Cr12MOV淬火件的5层不均匀残余应力。While conventional hole-drilling methods can only measure uniform residual stresses along a specimen′s depth,an incremental hole-drilling method is used to measure non-uniform residual stresses inside a specimen.The calibration constants matrix is calculated using the finite element calibration method,and a practical measurement technology of non-uniform stress is established.An agglutinate 3-D finite element model of a specimen with rosette is built using ANSYS software,and the calibration constants in each layer are calculated with a dividing-layer loading method.The calibration constants matrix is obtained when the hole depth reaches h=0.5 Dto completely release residual stresses,and is used to form the fivelayer non-uniform stresses with the five-step hole-drilling method.Then,the five-step incremental holedrilling method and the calculated calibration constants matrix are used to experimentally measure the nonuniform residual stresses within the Cr12 MoV quenching specimens.Comparing these measurements with the results of conventional hole-drilling methods shows that the finite element calibration method can simulate non-uniform residual stresses field inner specimen to calculate the calibration constants matrix.In addition,the five-step incremental hole-drilling results show that the five-layer non-uniform residual stresses can be built up in Cr12 MoV quenching specimens.高等学校博士学科点专项科研基金资助项目(20120121120036); 国家自然科学基金资助项目(50675200

非光滑叶片对叶栅流道内通道涡影响的实验研究

在低速平面叶栅风洞中对光滑叶片叶栅及三种非光滑叶片叶栅进行了实验研究,以研究与光滑叶片相比,非光滑叶片对叶栅流道内通道涡发展变化的影响.实验结果表明,与光滑叶片相比,非光滑叶片对叶栅流道内的通道涡有明显的影响,通道涡的位置沿节距方向移向流道中心处,沿叶高方向不变,通道涡的强度有所减弱.分析了非光滑叶片的影响原因

离子吸附型稀土矿开采机理研究进展

离子吸附型稀土矿的开采主要基于离子交换和稀土溶液运移。为实现离子吸附型稀土矿绿色高效开采，研究者们提出了一系列的开采工艺，并建立了相关的稀土运移和渗流理论。本文综述了目前现有或潜在的离子吸附型稀土矿开采工艺，重点分析了浸出动力学、塔板、对流扩散和外加电场驱动等稀土离子运移理论，探讨了开采过程风化壳中稀土溶液的渗流特性及影响因素，提出钙盐镁盐浸出、生物浸出和电动开采等开采工艺的优化思路，即应采用微观谱学、数值模拟和多学科交叉等手段加强稀土离子运移理论和风化壳中稀土溶液渗流特性的基础研究，实现离子吸附型稀土矿绿色高效开采