摘要：Bone screws are devices used to fix implants or bones to ***,conventional screws are mechanically fixed with thread and often face long-term failure due to poor *** improve osseointegration,screws are evolving from solid and smooth to porous and *** manufacturing(AM)offers a high degree of manufacturing freedom,enabling the preparation of predesigned screws that are porous and *** paper provides an overview of the problems currently faced by bone screws:long-term loosening and screw ***,advances in osseointegrated screws are summarized hierarchically(sub-micro,micro,and macro).At the sub-microscale level,we describe surface-modification techniques for enhancing *** the micro level,we summarize the micro-design parameters that affect the mechanical and biological properties of porous osseointegrated screws,including porosity,pore size,and pore *** addition,we highlight three promising pore shapes:triply periodic minimal surface,auxetic structure with negative Poisson ratio,and the Voronoi *** the macro level,we outline the strategies of graded design,gradient design,and topology optimization design to improve the mechanical strength of porous osseointegrated ***,this paper outlines advances in AM technology for enhancing the mechanical properties of porous osseointegrated *** osseointegrated screws with hierarchical design are expected to provide excellent long-term fixation and the required mechanical strength.

摘要：A new approach which adopted the idea of coupling bionics to improve erosion resistance was presented, by taking the desert scorpion as the research object. The anti-erosion characteristic rules and mechanism of desert scorpion's surface under the dynamics effect of gas/solid mixed media were researched, especially the comprehensive influence mechanism of surface morphology, microstructure, creature flexibility and many other factors was studied. Simulation by CFD software was applied to predict the relative erosion severity. Samples with the coupled bionic configurations and flexibility were produced. Experiment optimum design theory was employed to design experiment scheme. Silica sand of particle size of 105-830 m was used as the erodent. The erosion tests were carried out to validate the simulation results obtained. It is shown that the predicted results are in agreement with those obtained from the experiment. And contrast tests were carried out at the best and worst test points of erosion resistance for four samples. Contrast tests show that the erosion resistance trend occurs in such order with the best erosion resistance as coupling sample, groove, smooth and flexibility, and smooth, and the increasing rate of erosion resistances in sequence of 12.08%, 8.87%, 6.03% in the best test point. But in the poorest point, the increasing rate of erosion resistance is in sequence of 15.64%, 9.53%, 6.59%. The morphologies of eroded surface were examined by the scanning electron microscope, and the possible wear mechanism was discussed.

摘要：研究动物鞘翅的内部结构,为复合材料的结构设计提供设计依据,以东方白点花金龟(Protaetia orentalis)、臭蜣螂(Coprisochus)、星天牛(Anoplophora chinensis)和黄缘真龙虱(Cytister bengalensis)为研究对象,利用扫描电子显微镜对鞘翅断面进行了分析,并结合四种昆虫的生活环境,对观察到的鞘翅材料结构进行了分析和总结;针对鞘翅材料的结构特点,概括和总结了纤维模型和层状复合材料模型。研究结果表明:四种昆虫的鞘翅均由层状复合材料组成,在鞘翅内部发现的纤维(束)的形态略有区别。在花金龟鞘翅的纤维(束)形态有T型结构、正交叠层结构和分叉纤维结构;臭蜣螂鞘翅的纤维(束)形态有网状结构、块状凸起结构和刺状纤维结构;星天牛鞘翅的纤维(束)形态有空腔结构、螺旋结构、孔洞结构和刺状结构;龙虱鞘翅的纤维(束)形态有空腔和孔洞结构。这些天然生物纤维结构形式为轻质仿生复合材料的结构设计提供了可供学习和效仿的生物模型;基于四种昆虫鞘翅的内部结构分析,总结了常用的几种纤维模型,即分叉纤维模型和螺旋纤维模型,并对两种模型进行了模型示意,几种结构模型为复合材料特别是层状复合材料和纤维增强复合材料的仿生结构设计提供了依据。

摘要：本文中,我们针对误差为m.相依序列的固定设计的部分线性模型,运用经验似然方法和分组经验似然方法,构造了回归参数的对数经验似然比检验统计量,并且证明了分组经验似然比检验统计量在参数取真值时是渐近地服从卡方分布的.模拟计算表明分组经验似然方法的有效性.