全频段亚纳米精度氟化钙材料加工

考虑用CaF_2材料制作投影光刻物镜可以明显提高其性能指标,本文研究了CaF_2材料加工工艺的全流程,以实现CaF_2材料的全频段高精度加工。首先,利用沥青抛光膜和金刚石微粉使CaF_2元件有较好的面形和表面质量。然后,优化转速、抛光盘移动范围、压力等加工工艺参数,并使用硅溶胶溶液抛光进一步降低CaF_2元件的高频误差,逐渐去除加工中产生的划痕并且获得极小中频误差(Zernike残差)和高频粗糙度。最后,在不改变CaF_2元件高频误差的同时利用离子束加工精修元件面形。对100mm口径氟化钙材料平面进行了加工和测试。结果表明:其Zernike 37项拟合面形误差RMS值可达0.39nm,Zernike残差RMS值为0.43nm,高频粗糙度均值为0.31nm,实现了对CaF_2元件的亚纳米精度加工,为研发高性能深紫外投影光刻物镜奠定了良好基础。     

离子束抛光去除函数计算与抛光实验

由于传统的离子抛光工艺采用的确定去除函数的方法操作复杂且成本很高,本文提出了利用法拉第杯对离子束流空间分布进行测量、标定的方法,并计算得到不同离子源工作参数对应的去除函数。首先,基于离子束抛光材料去除原理,研究了离子束抛光过程中束流分布与能量对去除函数的影响,并提出简化的离子束抛光去除函数模型。然后,设计实验并得出离子束流空间分布与去除函数相关参数间的关系,计算得到了不同离子源工作参数产生的离子束流对应的去除函数。对硅和融石英玻璃的相关实验表明:利用法拉第杯扫描结果计算相同材料的去除函数的单位时间体积去除率与实际测量值误差小于2%。结合抛光实验,对Φ800mm碳化硅表面硅改性层平面镜进行抛光,得到的初始面形误差均方根(RMS)值为57.886nm,两次抛光后RMS值为11.837nm,收敛率达到4.89,满足精密光学加工对去除函数的确定性及精度的要求,并大大提升了确定去除函数的效率。     

一种光学材料高效超精密加工方法

提出了结合磁流变光整加工(MRF)与在线电解修整(ELID)磨削对各种光学材料进行超精密加工的方法,即采用ELID磨削进行预抛光以获得高质量表面,然后采用MRF进行精密抛光以进一步减小表面粗糙度和形状误差.利用该组合工艺对BK7玻璃、硅晶玻璃、碳化硅等光学材料进行了超精密加工实验,可以在短时间内使光学材料工件表面得到亚纳米级的表面粗糙度和峰谷值为λ/20(λ为单位波长,λ=632.8nm)的形状精度.     

光学材料磨削的亚表面损伤预测

基于压痕断裂力学理论,建立了工件表面粗糙度与亚表层损伤深度的理论关系模型,用于预测磨削加工脆性光学材料引起的亚表层损伤深度.利用磁流变角度抛光技术检测了不同磨削加工工艺条件下亚表层的损伤深度,验证了理论模型的正确性.分析了加工工艺参数对工件表面粗糙度及亚表层损伤深度的影响规律,提出了提高材料去除率的磨削加工工艺方案.分析结果表明:脆性材料工件的亚表层损伤深度与工件的表面粗糙度呈非线性单调递增关系.工件亚表层损伤深度及工件表面粗糙度均随着切削深度和进给速度的增加而增加,随着主轴转速的增加而减小.对比实验结果与理论模型预测结果表明,提出的模型可以准确、无损伤地的预测磨削加工引起的工件亚表层损伤深度.     

超光滑光学表面加工技术

现代科学技术的发展,在许多领域中提出了加工超光滑表面的要求。这种表面不仅要具备较高的面形精度和极低的表面粗糙度,同时要具有完整的表面晶格排布,消除加工损伤层。近年来国际出现了不少成功的超光滑表面加工技术,可以实现表面粗糙度小于1nm,面形精度优于30nm.本文介绍了超光滑表面的主要应用领域；从去除机理的角度讨论了BFP抛光、Teflon抛光、离子束加工、PACE加工、浮法抛光、延展性磨削等六种有代表性的超光滑表面加工技术；并对国内情况作了简单分析。     

化学刻蚀的光学元件面形修复

采用化学加工方法对光学元器件进行面形加工,可以避免传统的抛光工艺带来的亚表面缺陷和表面污染。实验中利用Marangoni界面效应有效控制化学液的驻留时间和驻留面积,并通过数控系统实现编程控制加工,进行了面形修复实验,利用轮廓仪测量了加工前后的表面粗糙度。结果表明,采用拼接小去除量多次加工的方法,有效地降低了面形误差,面形值由1.32 λ(λ=632 nm)减少到0.66 λ,粗糙度基本维持不变。利用此实验装置使基片面形得到修复,避免了传统加工方式带来的亚表面缺陷等问题,有利于强激光系统的使用。     

一种Al_2O_3陶瓷导轨的超精密加工方法

提出了700mm长Al_2O_3陶瓷导轨超精密加工的工艺流程;依次介绍了磨削、研磨使用的工艺方法和检测方法,并详细介绍了采用自行研发的超精密导轨研磨抛光机对导轨抛光的工艺方法、工艺参数和检测方法。采用Zygo平面干涉仪检测导轨面形,通过子孔径拼接技术,得到导轨面700mm×260mm表面面形误差最大峰谷值为0.78λt(λ=632.8nm),面形误差均方根值为0.1λ。     

磁流变抛光消除磨削亚表面损伤层新工艺

针对传统光学加工技术难于精确测量和控制亚表面损伤的特点,提出用磁流变抛光替代研磨工序并直接衔接磨削的新工艺流程。采用自行研制的磁流变抛光机床KDMRF-1000和水基磁流变抛光液KDMRW-2进行了磁流变抛光去除磨削亚表面损伤层的实验研究。结果显示,直径为100mm的K9材料平面玻璃,经过156min的磁流变粗抛,去除了50μm深度的亚表面损伤层,表面粗糙度Ra值进一步提升至0.926nm,经过17.5min磁流变精抛,去除玻璃表面200nm厚的材料,并消除磁流变粗抛产生的抛光纹路,表面粗糙度Ra值提升至0.575nm。由此表明,应用磁流变抛光可以高效消除磨削产生的亚表面损伤层,提出的新工艺流程可以实现近零亚表面损伤和纳米级精度抛光两个工艺目标。     

磁流变抛光消除磨削亚表面损伤层工艺研究

针对传统光学制造技术对亚表面控制局限性和磁流变抛光的特点,提出用磁流变抛光替代研磨工序直接衔接磨削工序的新工艺流程。采用自研的磁流变抛光机床KDMRF−1000和水基磁流变抛光液KDMRW-2进行了磁流变抛光去除磨削亚表面损伤层的实验研究。直径为100mm的K9材料平面玻璃,经过156min的磁流变粗抛,去除50um深度的亚表面损伤层,表面粗糙度Ra值提升至0.926nm,经过17.5min磁流变精抛,去除了200nm深度的材料,并消除磁流变粗抛产生的抛光纹路,表面粗糙度Ra值提升至0.575nm。应用磁流变抛光可以高效消除磨削产生的亚表面损伤层。磁流变抛光替代研磨工序直接衔接磨削工序的新工艺流程可以实现近零亚表面损伤和纳米精度抛光两个工艺目标。     

圆柱型永磁体磁流变抛光头设计及其参数优化

针对传统加工技术存在表面损伤、加工效率低的问题,将极具前景的面接触式超精密磁流变抛光技术应用到3C制造业中。对圆柱型永磁体磁流变抛光头在加工过程中的抛光垫的形貌进行了研究分析,发现圆柱型永磁体磁流变抛光头在加工过程中存在一种"环状效应",利用"环状效应"对圆柱型永磁体磁流变抛光头进行了结构设计,并对其进行了设计理念分析;对圆柱型永磁体抛光头在6061的铝合金工件上进行了单因素抛光实验,通过实验获得了最优参数。研究结果表明:该圆柱型永磁体磁流变抛光头能够实现环状加工区域的高效光滑平坦化加工,工件表面粗糙度达到52 nm,材料去除率达9.1μm/min,大大提高了磁流变抛光的效率,为面形精度在微米级的超光滑平面的制造提供了一种高效的加工方法。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.