KDP晶体超精密加工技术的研究

通过对KDP晶体等脆性材料的塑性域切削进行理论分析，研究实现脆性材料塑性域切削的条件。激光核聚变KDP晶体的3项主要技术指标是：表面粗糙度、波纹度和透射波前。通过分析影响这3项技术指标的因素。提出了实现KDP晶体精密加工的超精密机床和工艺参数。通过理论分析与实验。研究了晶向、刀具前角、刀具圆弧半径和进给量等参数对表面粗糙度的影响，最终给出KDP晶体精密加工的最佳工艺参数。     

脆性材料磨削加工损伤及工件强度研究

通过对脆性材料磨削加工损伤机理的分析,说明磨削方向与脆性材料强度分布的各向异性有关。提出一种外圆磨床磨削圆柱类脆性材料的运动模式,并对磨削加工试件进行强度试验、Weibull统计分析和断口显微分析,结果表明对于外圆磨削,改变磨削加工方向,脆性材料工件的轴向抗拉强度可以提高30%。     

KDP晶体光学零件超精密加工技术研究的新进展

KDP晶体作为优质的非线性光学材料 ,被广泛的应用于激光非线性光学领域。由于大型KDP晶体具有一系列不利于光学加工的特点 ,因此被公认为是最难加工的光学零件。本文概述了KDP晶体超精密磨削和磁流变抛光的加工方法 ,阐述了KDP晶体光学零件单点金刚石加工技术的研究现状 ,并详细地分析了单点金刚石切削加工时机床精度、加工工艺参数、装夹变形、晶格方向变化、金刚石刀具几何参数、冷却液等对加工表面质量 (平面度、表面粗糙度、小尺度波纹等 )的影响     

KDP晶体塑性域切削技术研究

通过对KDP晶体等脆性材料压痕实验中的塑性行为分析,说明了实现KDP晶体等脆性材料塑性域切削的可行性.通过对脆性材料的切削模型进行分析,阐明了刀具几何尺寸以及切削用量对KDP晶体切削过程的影响.分析已有模型的不足,同时提出了从微观角度建立材料脆性断裂判据,以完善KDP晶体塑性域切削机理的研究思路.     

脆性材料磨削模式与表面粗糙度

对国内外有关脆性材料的磨削模式及表面粗糙度的研究进展进行了综述 ,为获得高质量的脆性材料产品、实施脆性材料的精密与超精密磨削提供有益的参考。     

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.     

脆性材料磨削加工损伤及工件强度研究

通过汇总脆性材料的磨削数据进行数据分析．说明脆性材料中强度的各种属性与磨削加工的方向有关。并且尝试提供柱状脆性材料的外圆磨床加工方法，对这种加工模式下的实验件进行各项测试和分析。其结果说明了在外圆磨削方式下加工的方向不同，工件各方向下的韧性，强度可增加30％。     

石英玻璃超精密磨削加工的表面完整性研究

为了实现石英玻璃的高效低损伤超精密磨削加工,研究不同粒度金刚石砂轮磨削石英玻璃的表面和亚表面质量,建立表面粗糙度与亚表面损伤深度之间的关系模型。通过石英玻璃磨削试验研究400#、1 500#、2 000#和5 000#金刚石砂轮磨削石英玻璃的表面微观形貌、表面粗糙度及其亚表面损伤深度,分析相应的材料去除方式;基于压痕断裂力学理论分析脆性域磨削石英玻璃时工件表面微观形貌和亚表面微裂纹的形成机理,建立表面粗糙度PV值和亚表面损伤深度SSD之间的定量关系。研究结果表明:随着砂轮粒度的减小,石英玻璃磨削表面的凹坑、微裂纹、深划痕等缺陷逐渐减少,表面粗糙度Ra和PV以及亚表面损伤深度SSD均随之明显减小,从400#砂轮磨削表面的R_a 274.0 nm、PV 5.35μm和SSD 5.73μm降低至5 000#砂轮磨削表面的Ra 1.4 nm、PV 0.02μm和SSD 0.004μm。500#和1 500#砂轮磨削表面的材料去除方式为脆性断裂去除,2 000#砂轮磨削表面的材料去除方式同时包括脆性断裂去除和塑性流动去除,但以塑性流动去除为主,5 000#砂轮磨削表面的材料去除方式为塑性流动去除;脆性域磨削石英玻璃的表面粗糙度PV与亚表面损伤深度SSD之间满足SSD=(0.627～1.356) PV~(4/3)的数学关系。     

电泳磨削技术及其应用

利用超细磨粒的电泳效应实现一种磨削技术称之为电泳磨削,通过超细磨粒电泳吸附层的研究,阐述电泳磨削的机理,提出了自进给电泳磨削新工艺。通过加工实验介绍电泳磨削技术在硬脆性材料精密加工中的应用。研究结果表明,该加工技术能明显改善脆性材料的表面粗糙度和破损率。     

脆性晶体的超精密加工

用单刃金刚石车削试验研究超精密加工脆性晶体材料的机理。通过讨论加工参数和材料特性来研究脆塑性转换机理。重点研究了加工单晶材料时晶向对临界切深、微切削力和表面粗糙度的影响；还探讨了加工多晶材料时晶界台阶的形成。超精密加工各种脆性晶体都可得到各向同性的纳米级表面粗糙度的光学表面。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.