Size effects on plastic deformation behavior in micro radial compression of pure copper

Micro radial compression tests were carried out on cylindrical specimens of pure copper polycrystals with different grain sizes. Experimental results indicated that phenomena of decreasing forming force, increasing scatter of forming force and more irregular surface topography occurred with the increase of grain size. A modified surface model based on dislocations pile-up in surface layer grains, and a flow stress scattering formulation based on standard deviation and grain size distribution were proposed to analyze size effects on forming force in micro compression. The inhomogeneous deformation of surface layer grains was discussed by the main deformation manner of rotation. A good agreement with the experimental results was achieved.

中国农村地区公共卫生资源投入比城市地区更无效吗

基于投入的非径向压缩测度效率结果表明,2005—2009年中国城乡公共卫生服务系统的投入产出技术效率总体呈下降趋势。相对于城市而言,中国农村地区的技术效率较高,说明农村乡镇卫生院和社区卫生服务中心的平均运营效率高于城市医院。无论农村还是城市地区,医疗机构固定资产投入的可压缩比都高于卫生从业人员,说明中国公共卫生医疗机构的设施和设备投入存在着相对结构性"过剩"。进一步的配置无效测度表明,中国城乡公共卫生资源配置无效程度呈现先下降后上升的趋势,其中城市地区的配置无效程度平均要高于农村地区,但差距逐年递减。