Determination of the Clearance of a Plane Slider Bearing Realizing Maximum Rigidity

The optimum shape of the base of a slider traveling over a plane surface is established. The variational problem of determining the shape of the clearance with an incompressible isothermal lubricant ensuring maximum rigidity of the lubricant layer for a given slider load capacity is formulated and solved.     

Particle size analysis of perfluorocarbon emulsions in a complex whole blood matrix by sedimentation field-flow fractionation

The goal of this study was to show that sedimentation field-flow fractionation (SdFFF) could be used to study changes in the particle size distribution of perfluorocarbon (PFC) emulsion droplets in ex vivo whole blood samples. A PFC emulsion containing 40% w/v perfluorooctyl bromide (PFOB), 20% w/v perfluorodecyl bromide (PFDB), and 6% w/v egg yolk phospholipid (EYP) was manufactured by high pressure homogenization. The emulsion was infused intravenously to rats at a dose of 2.7 g PFC/kg body weight. Blood samples were collected at 0, 3, 6, and 24 h and analyzed (without additional sample manipulation) by SdFFF. Excellent chromatographic separation between the blood components and PFC emulsion droplets was achieved. After infusion, the particle size distribution broadened slightly. With time, the larger sized droplets were selectively removed by circulating monocytes and tissue resident macrophages of the reticuloendothelial system, causing the particle size distribution to shift to lower median diameters. SdFFF is an excellent technique for studying the in vivo stability of colloidal drug particles following intravenous administration.     

机构运动副间隙被动控制研究

将阶跃函数与牛顿二状态相结合 ,考虑曲柄非匀速运转 ,对含间隙平面连杆机构的副间分离与碰撞过程建立了动力学统一模型 ,利用该模型 ,引入粘弹性阻尼被动控制技术 ,通过算例分析了被动控制的效果。分析结果表明 ,在不改变机构基本参数的情况下将粘弹性材料引入到机构的间隙铰接处大大降低碰撞时引起的冲击效应 ,提高了机构运转的的稳定性 ,同时为含间隙机构控制领域的研究提供了新思路     

流体润滑状态下磨粒尺寸对液压泵磨损的影响

本文研究了流体润滑状态下磨粒尺寸对液压泵磨损的影响。结果表明,在液压系统中,泵的磨损主要决定于磨粒与泵内关键运动副动态间隙之间的尺寸关系:尺寸小于动态间隙的磨粒影响很小;尺寸明显比动态间隙大的磨粒不会对泵产生磨损作用;尺寸与动态间隙很接近的磨粒能使泵发生严重磨损。作者还利用扫描电子显微镜对流体润滑状态下三体磨粒磨损中的磨屑形貌进行了观察与分析,并且提出了控制液压系统中磨粒损磨的可行施措。     

The shearing edge of tracked vehicle – Soil interactions in path clearing applications utilizing Multi-Body Dynamics modeling & simulation

Tracked vehicle – soil interactions were modeled and analyzed to compare the mobility of two notional path clearing implements pushed by a tracked vehicle. This exploration assesses the capabilities and limitations of the state-of-the-art in tracked vehicle dynamics modeling and simulation over soft-soil terrain. Unique modeling and simulation methods to stretch the capability of the current state-of-the-art contribute to the overall discussion. One path clearing implement was a roller and rake combination. The other was a quickly rotating flail system that cleared a definitive path by impacting and flinging the soil away. Geotechnical forcing functions implemented Coulomb’s lateral earth pressure theory and Terzaghi passive soil failure models to compute the forces at the soft-soil – implement interfaces. Coulomb theory was reimagined to account for anomalies present when modeling the flail, mainly its arced motion and non-semi-infinite soil resistance zone. The path-clearing implements were simulated over discrete events and compared by means of load and acceleration time histories. The discrete events include side-slopes, grades, half-rounds, potholes, cross country terrain, and ‘V’ shaped ditches (V-ditch). Overall, the flail system experienced lower peak loads at the interface brackets and lower peak accelerations at the vehicle’s center of gravity than the roller-rake system.     

短生命周期产品供应链清仓收入共享契约研究

基于快速反应策略的适时清仓,是提高短生命周期产品供应链运营效率及加速产品更新的有效方法。考虑由一个零售商和多个配件供应商组成的两级短生命周期产品组装供应链系统,当市场需求随机变化时,建立了基于清仓收益共享的决策模型,从集中和分散控制两个角度,比较分析了有清仓收入共享和不考虑清仓收入共享下,供应链的总产量和利润的变化。理论推导和数值解分析表明,在考虑清仓收入共享下,供应链的市场供给量增加;而且,在清仓收入共享契约下,供应链利润依据成员成本比重及所分担风险率而得到合理分配,进而提升了供应链的整体协作效益。     

航空发动机叶尖间隙影像测量系统及其标定

针对航空发动机装配过程中叶尖间隙的测量,设计了一种影像测量系统,采用基于PC+运动控制卡的开放控制系统,通过PID控制实现对相机位置的精确控制。提出基于相机位置的精确快速完成相机标定,可在线准确测量出叶尖间隙值。相比其他光学影像测量系统及传统塞尺,该测量系统无需高精度标定参考物,可实现装配过程在线测量,测量范围为1 mm时误差小于20 m。     

乳化液膜清除未结合胆红素

高未结合胆红素症 (Ｈｙｐｅｒｂｉｌｉｒｕｂｉｎｅｍｉａ)是新生儿常见疾病 .胆红素在血液中的浓度过高 ,会伤害婴儿的大脑 (核黄疸 ) [1].肝昏迷患者的症状与胆红素在血液中含量过高也有直接关系 ,迅速有效地将其清除可使患者症状缓解[2 ],迄今为止 ,清除胆红素的研究主要集中在以吸附剂吸附为基础的血液灌流方法 ,所用的吸附剂主要有活性炭和大孔吸附树脂 ,活性炭的吸附选择性和血液相容性都比较差 ;大孔吸附树脂的吸附选择性和血液相容性等方面有待进一步提高[3],特别是在吸附未结合胆红素时 ,清除率低、清除速度慢 ,难以满足临床方面…     

A free rectangular plate on elastic foundation

In the theory of elastic thin plates, the bending of a rectangular plate on the elastic foundation is also a difficult problem. This paper provides a rigorous solution by the method of superposition. It satisfies the differential equation, the boundary conditions of the edges and the free corners. Thus we are led to a system of infinite simultaneous equations. The problem solved is for a plate with a concentrated load at its center. The reactive forces from the foundation should be made to be in equilibrium with the concentrated force to see whether our calculation is correct or not.     

叶顶间隙对环形叶栅三维粘性流场影响的数值分析

１前言考虑叶顶间隙影响的三维叶栅粘性流场特性的数值模拟是当今比较流行的研究课题。顶部泄漏流动的研究对更准确分析、设计三维叶栅具有重要意义。近年来,国内外的学者使用了多种不同的数值方法及实验方法对叶顶间隙流进行研究。然而,以往的计算往往局限于直列叶栅,...