用于地面模拟平台测试光学相机的设计

航空相机检测设备在出厂前需要更高精度相机调试,设计了一种应用于航空相机检测设备-地面模拟平台调试的相机。该相机通过使用非球面镜提高相机的图像质量并减轻整体重量,要达到相同成像效果的球面镜组需要8片透镜,使用非球面镜减轻了相机的重量和体积,设计的光学系预期统焦距为80 mm,最终光学系统的MTF优于34%@91 lp/mm。投入加工并组装相机测试,测试结果表明,非球面镜片达到制造标准,相机的分辨率、成像清晰度和焦距均符合设计要求。     

线性改变切削深度对单晶铜纳米切削的影响

针对单晶铜纳米切削,利用分数阶微积分理论,建立了切削力主趋势分量对切削深度的依赖模型,以描述非线性的尺寸效应。利用近似熵测度,研究了在不同切削阶段中切削力高频扰动的复杂性。研究表明,在切入阶段,切削力经历了由负值到较大正值的突变,工件材料出现弹性失稳以及初期的弹塑性转变;在切削阶段,切削力的主趋势分量呈现明显的低频峰谷现象和非线性的尺寸效应。通过观测工件材料内部的位错形核及位错运动,详细地解释了切削力在线性改变切削深度条件下呈现这种演变特征的根本原因。     

Negative linear compressibility of generic rotating rigid triangles

The compressibility properties of systems consisting of generic rotating rigid triangles are analyzed and discussed.It is shown that these systems which are usually associated with auxeticity can exhibit strongly anisotropic properties for certain conformations, which may give rise to the anomalous property of negative linear compressibility(NLC), that is, the system with particular geometry will expand along one direction when loaded hydrostatically. It is also shown that through carefully choosing the geometric features(i.e. the dimensions and the alignment of the rotating triangles as well as the angles between them) and the direction along which the linear compressibility is measured, one may control the magnitude and range of the NLC. All this provides a novel but effective method of manufacturing the systems which can be tailored to achieve particular values of NLC to fit particular practical applications.