Research on the Residual Error Evaluation Method for Deterministic Polishing of Aspheric Optics

研究非球面光学元件确定性抛光中表面残余误差的评价方法。对两种非球面残余误差的评价方法,分别为轴向误差法和法向误差法,进行理论研究。指出非球面的残余误差理论上应使用法向误差法来评价,并提出一种基于轴向残余误差求解法向残余误差的方法,继而对二者进行比较发现两者存在一定的偏差,并且差值从非球面的中心向边缘方向逐渐增大。以气囊抛光和数控小磨头抛光为例,通过试验表明使用轴向误差法评价残余误差,进行确定性抛光引入了不同程度的加工误差,引入的加工误差的大小与非球面光学元件的口径和顶点曲率半径的比值(即“相对孔径“)成正相关,故对于相对孔径较小的非球面光学元件在确定性抛光中可使用轴向误差法替代法向误差法作为残余误差的评价方法,反之,则应使用法向误差法。Residual error evaluation method for deterministic polishing of aspheric optics is studied.Two residual error evaluation methods, which are axis-direction error method and normal error method respectively, are researched theoretically.It's inferred that the residual error of aspheric surface should be evaluated by normal error method.A new approach is proposed to calculate normal direction residual error on the basis of the axis-direction residual error of the aspheric surface.There exists difference between these two kinds of error which increases from the center of the aspheric optic to the edge through the comparison of them.Taking bonnet polishing and numerical controlled small tool polishing as examples, experiments are made to quantitatively prove that using axis-direction error method to evaluate residual error in deterministic polishing would introduce different degrees of processing error.It's found that the processing error is positively correlated with the relative aperture of aspheric optics, which is the ratio of the optic's aperture and vertex's curvature radius.Therefore, it is recommended to use axis-direction error method instead of normal error method as the evaluation method of the residual error during deterministic polishing aspheric optics with relatively small relative aperture; the opposite is the other way around.国家科技重大专项资助项目(2013ZX04006011-206

Dynamic Removal Function Modeling of Bonnet Tool Polishing on Optics Elements

目前对于光学元件气囊抛光系统驻留时间的求解都是基于静态的去除函数,然而实际抛光过程中,抛光头不断地移动,故对于动态去除函数的研究显得尤为必要。通过有限元仿真分析的方法得到动静态接触区的轮廓和接触应力分布数据,发现对于平面工件,动静态接触区均为圆形,而且大小基本一致,且动态接触区应力分布与静态接触区应力分布相比,其峰值点沿抛光头移动的相反方向偏移。在此基础上,根据静态接触区应力呈类高斯分布的理论,利用最小二乘拟合的方法,推导出动态接触区的应力分布函数。通过搭建动静态接触区轮廓提取装置,设计不同下压量下动静态接触区的轮廓提取试验,验证有限元仿真结果的准确性。基于仿真和试验结果推导出动态去除函数,对其进行数值仿真,并与静态去除函数进行对比,发现前者去除率偏小,而且最低点也发生偏移。The dwell time function of the bonnet tool polishing on optics elements is achieved based on static removal function in recent studies.But the polishing tool keeps moving during the process,it's necessary to do the research on dynamic removal function.The static and dynamic contact zone is acquired through finite element simulation analysis,and so is the contact pressure.Both of the contact zones are circle and the size of them are almost the same.The peak point of the dynamic contact pressure has an offset contrary to the direction of the tool movement compared to the static contact pressure.The dynamic contact pressure distribution function is deduced by using the least square method based on the theory that the static pressure distribution function is a modified Gaussian function.The device which can extract both the dynamic and static contact zone is set up to capture them on the condition of different offset.Then the simulation results are verified.The dynamic removal function is deduced and numerical simulated based on the forward simulation and experiment results.The removal rate of the dynamic removal function is smaller than the static removal function and its nadir has a deflection compared to the latter.国家自然科学基金(51075343); 厦门市科技计划(3502Z20113007)资助项

Control Techniques of Bonnet Polishing for Free-form Optical Lenses with Precession

针对自由曲面光学元件的加工特点,研究气囊抛光自由曲面光学元件进动运动控制技术,用于求出气囊工具进动过程中两虚拟轴的转角,实现对气囊自转轴空间位置的控制。以气囊自转轴为研究对象,由于自由曲面光学元件上每个点的法线三维坐标都不相同且气囊进动抛光过程中气囊自转轴与工件加工点局部法线夹角不变,提出建立基坐标系和抛光点对应三维空间坐标系的方法,得到抛光过程中气囊自转轴的空间位置变化情况,而后利用旋转坐标变换得到气囊抛光进动运动控制模型;在所建立的自由曲面光学元件气囊抛光进动运动控制模型中加入控制算法,求出抛光自由曲面光学元件各点时气囊工具两个虚拟旋转轴的转角。利用MATlAb对自由曲面光学元件不同方向截面进行仿真抛光试验,得到自由曲面各方向上气囊抛光进动运动曲线以及仿真进动角曲线,结果证明了自由曲面光学元件气囊抛光进动运动控制模型及控制算法的正确性。Control techniques of bonnet polishing free-form optical lenses with 'precession' is studied,according to the processing characters of free-form optical lenses,to figure out the rotating angles of two virtual axes of bonnet tool,which lead to the controllability of spin axis of bonnet tool.The spin axis of bonnet tool is taken as the object,due to the difference of the local normal of each polishing point and the angle between the spin axis of bonnet tool and local normal is keeping constant in polishing process,a method about how to set up basic coordinate and corresponding coordinate of polishing point is proposed,aiming to get the positions of spin axis of bonnet tool in polishing process,by which a movement model can be obtained by combining with rotating coordinate transformation;Then control algorithm is added to the movement model,and rotating angles of two virtual axes of bonnet tool when polishing each point on free-form optical lenses are calculated.At the end,simulations in polishing different directions of free-form optical lens in Matlab are carried out,to get the curves of precession control and the simulated precession angles,the results reveal that the movement model and control algorithm presented are both correct.国家自然科学基金(51075343); 厦门市科技计划(3502Z20113007)资助项

A dynamic coupling model for hybrid atomistic-continuum computations

A dynamic coupling model is developed for a hybrid atomistic-continuum computation in micro- and nano-fluidics. In the hybrid atomistic-continuum computation, a molecular dynamics (MD) simulation is utilized in one region where the continuum assumption breaks down and the Navier-Stokes (NS) equations are used in another region where the continuum assumption holds. In the overlapping part of these two regions, a constrained particle dynamics is needed to couple the MD simulation and the NS equations. The currently existing coupling models for the constrained particle dynamics have a coupling parameter, which has to be empirically determined. In the present work, a novel dynamic coupling model is introduced where the coupling parameter can be calculated as the computation progresses rather than inputing a priori. The dynamic coupling model is based on the momentum constraint and exhibits a correct relaxation rate. The results from the hybrid simulation on the Couette flow and the Stokes flow are in good agreement with the data from the full MD simulation and the solutions of the NS equations, respectively. (c) 2007 Elsevier Ltd. All rights reserved

Zooplanktonic diversity in the western Pacific

西太平洋区是全球海洋生物种源中心,许多类群的最高物种多样性都出现于该区域,因此,在该区开展种类多样性的研究不仅重要和必要,而且具有在跨国尺度上进行综合管理和相互合作的迫切性。本文在西太平洋的浮游动物样品鉴定分类、编目、文献资料整理和分析的基础上,记录和编入西太平洋10个浮游动物类群2,658种(含亚种),隶属于206科675属,其中水螅水母类99科251属697种,栉水母类12科22属59种,浮游软体动物14科35属86种,介形类8科89属416种,桡足类51科156属908种,糠虾类4科58属202种,磷虾类2科8属56种,十足类8科22属105种,毛颚类5科8属48种,被囊类5科26属81种。The western Pacific region has been operating as a centre for the origin of marine biodiversity: the richest diversity of many marine taxa was found in these waters.Therefore,biodiversity research and con-servation efforts in this area are necessary in order to promote the integrative and international management of this resource.The present work is a compilation of numbers of all the families,genera and species of ma-jor taxa of zooplankton known in the western Pacific Ocean(106°–150°E,0°–44°N).In all,2,658 zooplank-tonic species(including subspecies) belonging to 206 families and 675 genera have been recorded from taxonomic identifications and literature,99 families,251 genera and 697 species belong to the Medusozoa,12 families,22 genera and 59 species to the Ctenophora,14 families,35 genera and 86 species to the pelagic Molluscs(Pteropoda and Heteropoda),8 families,89 genera and 416 species to the Ostracoda,51 families,156 genera and 908 species to the Copepoda,4 families,58 genera and 202 species to the Mysidcea,2 fami-lies,8 genera and 56 species to the Euphausiacea,8 families,22 genera and 105 species to the Decapoda,5 families,8 genera and 48 species to the Chaetognatha,5 families,26 genera and 81 species to the Tunicata.908专项“中国海洋生物种类名录和图谱”(908-ZC-II-02)和908专项海洋生物样品库;科技部基础工作专项“我国和邻近西北太平洋海洋生物物种编目和分布图集编制”(2006FY220700

Transient Temperature Distribution in a Sheet Metal by Low-Energy Laser Scanning

Low-energy laser-heating techniques are widely used in engineering applications such as, thinfilm deposition, surface treatment, metal forming and micro-structural pattern formation. In this paper,under the conditions of ignoring the thermo-mechanical coupling, a numerical simulation on the spatialand temporal temperature distribution in a sheet metal produced by the laser beam scanning in virtue of thefinite element method is presented. Both the three-dimensional transient temperature field and thetemperature evolution as a function of heat penetrating depth in the metal sheet are calculated. Thetemperature dependence of material properties was taken into account. It was shown that, after taking thetemperature dependence of the material absorbance effect into consideration, the temperature change ratealong the scanning direction and the temperature maximum were both increased

一种新型的碳纤维和碳纳米管化学镀镍工艺

碳纤维是最重要的复合材料增强体之一,而碳纳米管比碳纤维具有更好的力学性能,对他们的表面改性将会对复合材料性能有很大影响.试验实现了一种对碳纤维和碳纳米管通用的化学镀镍工艺.通过对基体较好的预处理,在基体上成功地完成了化学镀镍并且较好的控制了镀层成分.同时还探讨了施镀温度、pH值和搅拌方式等对镀层的影响,试验发现pH值控制在9～10之间,温度控制在70 ℃附近并采用氮气搅拌可以获得较满意的施镀效果

基于ANSYS CFX 的细沟水流切应力分析

为探明细沟断面的发育过程，利用流体力学软件ANSYS CFX 15. 0. 7 对细沟的发育变化过程进行数值仿真， 研究细沟断面水流流速及切应力分布，结合实测细沟发育，分析了细沟断面水流流速特征和切应力特征，从计算流 体力学角度探索了细沟在水流冲刷情况下的断面发育机理。结果表明: 利用CFX 数值仿真建模的方法，得到了染 色法测定细沟水流流速时的修正系数为0. 78。宽浅式细沟断面切应力小于窄深式断面，细沟水流切应力主要集中 在1. 41 ～ 2. 10 Pa 之间。水流切应力决定着细沟断面的发育，断面各点的切应力与断面各点发育较为吻合，切应力 与断面各点的发育密切相关。</p