电磁扭杆离合器工作沟槽接触应力分析

电磁扭杆离合器工作沟槽既是离合器传递力矩的关键结构,又是影响弹性扭杆组件结合-分离的重要部位.以某新型电磁扭杆离合器为研究对象,提出了工作沟槽优化设计方法.首先通过理论分析计算得到钢球与工作沟槽结合状态时的接触应力;然后利用有限元分析软件ANSYS Workbench进行仿真验证,通过比较理论计算值和仿真分析结果,进一...     

Voluntary intake of several planted pastures by sheep and an assessment of NDF and IVDOM as possible predictors of intake

The aim was to study the quality and quantity of pasture selected by sheep on various planted pastures. A further aim was to assess NDF and IVDOM as easy measurable parameters for use in equations to predict intake. Pasture samples were collected using oesophageal‐fistulated sheep and from knowledge of the in vitro digestibility of these samples and the total faeces voided as measured with faeces bags, intake was calculated. Pastures observed included ryegrass, cocksfoot, C. dactylon, Smuts finger, triticale, E. curvula, Eragrostislucerne combination, lucerne and sainfoin. Nitrogen content of oesophageal samples varied between 2,3 and 5,1%, NDF between 33 and 65% and IVDOM between 50 and 80%. Intake of grass DOM varied from 24,4 to 43,3 g/kg W^0,75/day for lambs and from 29,0 to 37,4 g/kg W^0,75/day for mature wethers. DOM intake on the two legumes was generally poor and varied between 13,7 and 22,9 g/kg W^0,75/day. Although some of the variation in voluntary intake is accounted for by the variation in NDF and IVDOM, these two parameters are of limited value as general predictors, but may be used in selection indices.     

汽车前围上盖板流水槽结构设计

通过对常用前围上盖板流水槽结构介绍,分析其存在的优缺点.由于某车型造型“C”点相对比较靠后,前围上盖板流水槽结构设计需要解决常用流水槽结构强度低的问题.某车型流水槽结构设计与常用结构完全不同,增加上盖板前内板,使前风窗玻璃安装有较好的强度.前围上盖板安装板独特的结构设计,保证能储存一定流水量,阻止雨水流入发动机舱.     

Feline hyperthyroidism — A review

The efficacy of selenium dioxide (SeO₂) was similar to sodium selenate (Na₂SeO₄.10H₂O), in terms of increasing and maintaining blood Se concentrations. when administered orally twice daily to give 0.64 rng of Se/dav to grazing dairy cows for 56 days.     

齿轮泵圆形卸荷槽下的困油压力分析

计算齿轮泵圆形卸荷槽下的卸荷面积和对应的困油压力。以困油的膨胀过程为例,首先通过啮合点位置和圆形槽圆形轮廓与从动轮齿廓和主动轮槽廓的交点位置计算,给出卸荷面积的精确计算方法,其结果由虚拟的测量数据验证;其次由流体体积弹性模量定义所构建的困油模型,对圆形、矩形两卸荷槽下的困油压力分别进行仿真运算,结果则被相关文献提供的试验结果所验证。结果表明:卸荷面积的计算结果与虚拟测量结果非常吻合;困油压力峰值的仿真结果与现有试验结果也非常吻合。当泵采用小侧隙大卸荷槽间距时,应多采用矩形槽,以提供更大的卸荷面积;当泵采用大侧隙小卸荷槽间距时,应当多采用圆形槽,以降低加工维修成本。     

黄土高原集流槽的发育与控制

本文从细沟交汇与分叉和人为耕作作用两方面论叙了集流槽的发生发展机制,在搞清其发生发展规律的基础上,讨论了它在现代侵蚀沟和微地貌分类中的归属问题,指出它应作为细沟、浅沟、切沟系列以外一种特殊的侵蚀微地形。将发生在集流槽底部,宽度30～50cm,其深度与耕作层等深的小侵蚀沟称为浅沟。嗣后讨论了用细沟、浅沟分布的不均匀性拟定的集流槽发育系数d,来鉴别集流槽发育程度的方法,分析了集流槽与细沟侵蚀、浅沟侵蚀的关系。最后提出控制集流槽发展,防止浅沟、切沟侵蚀的两项措施。     

螺旋槽端面密封的刚度特性

为了解决螺旋槽端面密封在不同环境下的刚度设计问题,对其刚度特性进行了数值计算和影响因素分析.采用Possion方程定解的贴体坐标生成计算网格,将螺旋槽不规则曲线边界转换为规则矩形边界.将Reynolds方程转换到计算平面,采用基于贴体坐标系的有限差分方法对Reynolds方程进行数值求解,得到螺旋槽密封刚度特性数值模型,并分析了内外径比和转速对密封刚度特性的影响.结果表明：当其他参数固定,内外径比为0.5～0.6时,流体膜具有最大的刚度;随着密封外径的增大,刚度整体有所提高,内外径比对刚度的影响更为显著;流体膜刚度随转速的升高而线性增大,并且内外径比为0.5～0.6时,刚度增大幅度最大;对于窄面密封,当扰动随转速成比例提高而导致密封刚度不足时,必须提高内外径比才能保证密封的正常工作.     

The Research and Development of the Pilger''s CARD and 3D Modeling

The paper expatiates the principle of the pilger mill roll groove. A math model for optimization is set up based on various factors concerning the roll groove including the deformation theory, design process and selection of the parameters, etc. Meanwhile, the CARD techniques are combined. As a result, a software for the roll groove optimization is developed that provides such functions as groove data management, groove profile plotting and groove data printing, being a basis for relevant technological decision and groove optimization. Meanwhile, the principle and realization of complex curves are discussed. The 3D modeling is achieved by the exchange of data that is based on the CARD system.     

Right subclavian artery anomaly in an adult Friesian horse

This report describes an unusual vascular ring anomaly (VRA) that resulted in repeated oesophageal obstruction in an adult horse. Oesophagoscopy identified a luminal obstruction with secondary mucosal sloughing. Post mortem findings revealed oesophageal and tracheal stenosis secondary to an aberrant right subclavian artery. The presence of the VRA may have resulted in repeated oesophageal impactions in an adult horse and the hereditary potential for this defect should be considered.     

螺旋槽干气密封系统轴向振动响应及结构优化

以密封静环为振子建立了气膜-密封环流固耦合系统轴向振动的计算模型,利用PH线性化方法、复函数分离变量法和小参数迭代法近似求解雷诺方程,求得了气膜动压近似解析式,进而求出了气膜推力.以此推力作为振动方程的激振力,建立了轴向单自由度受迫振动方程;利用龙格-库塔法求解,获得了不同螺旋角和槽深响应的振动相轨图和时间历程图,并分析了螺旋角和槽深对振动位移的影响.研究结果表明：螺旋角和槽深对振动参数均有影响,其中螺旋角对振动最为显著.改变螺旋角和槽深数值可以控制密封环的振幅,通过选择其最佳值可以保证干气密封运行的稳定性.本实例的最佳值为螺旋角74°58′48,″槽深5μm,与试验数据基本一致.