不确定环境下模具制造项目群随机调度

为确保模具按时交货,通过分析模具制造项目工期、费用与报酬的不确定性,以及项目返修频繁的特点,建立了基于离散时间马尔可夫链的模具制造项目群随机演化模型,并提出了求解该随机动态规划模型的算法框架.通过启发式策略仿真和Q学习,有效解决了"维数灾难"问题.最后结合示例阐述了该算法的执行过程,及其可行性与可靠性.     

模具开发过程的工作流建模与仿真优化

首先介绍了工作流技术,然后运用工作流技术对模具开发过程进行了建模,最后采用工作流仿真软件对所建立的工作流模型进行了仿真分析和优化.通过对模具开发过程进行工作流建模和仿真优化,指出了工作流技术能够为模具企业的生产管理方式变革提供新的思路.     

基于有限元模型的弹性体模具优化设计

应用UG7.0软件建立某弹性体模具总成的三维模型,并通过软件集成技术在有限元软件NX Nastran环境下对模具的重要零件模套进行了有限元分析,获得了该零件在工作状态下的应力分布及位移分布云图,并根据其应力分布情况重新进行了优化设计.仿真结果表明该模套满足强度设计要求,其设计是合理的.这为零部件的结构设计与优化提供了有价值的参考.     

不确定环境下模具群项目计划制定方法

针对模具项目群制造过程的不确定性和资源需求的动态性,建立了基于离散时间Markov的模具制造项目随机演化模型.基于该模型,提出一种分阶段求优的模具项目计划制定方法,将项目群的每一个任务视为一个独立的阶段,以最小化每个阶段的完工时间为目标,利用动态规划方法对每一个阶段的任务求解最优的调度策略.通过仿真算例将该方法与三种启发式算法进行比较分析,结果表明该方法在不确定环境下制定模具项目群项目计划时具有明显的优越性.     

数模比对在复杂模具曲面检测中的应用研究

针对复杂模具表面曲面检测难以及检测要求高等问题,提出了应用数模比对方法进行模具曲面精度检测。以带复杂滚花特征的车用皮带轮作为检测对象,通过激光扫描仪采集获取点云数据模型,在Geomagic Qualify软件平台上对点云数据模型和原始CAD模型进行数模比对,实现对模具整体偏差、重要截面以及尺寸精度的检测。该研究为复杂模具表面的检测提供了快捷、方便、准确的方法。     

基于CATIA的模具结构参数化及虚拟装配

应用参数化驱动建模理论,建立直齿轮冷挤压成形模具三维参数化驱动的模型,并在虚拟现实系统中完成模具装配体的可装配性分析和干涉性分析,对可能出现的装配碰撞和干涉进行检测,该设计对提高设计效率和质量有参考意义.     

隐形眼镜模具超精密加工与测量的集成方法研究

根据隐形眼镜模具的超精密加工原理和高精度要求,对影响模具加工质量和效率的主要因素进行了综合分析,分析和加工试验证明水平方向的对刀误差是其中最关键的因素。以Nanotech 250 UPL机床为加工设备,结合Zygo轮廓仪的精密检测原理,对水平方向的对刀误差构建了一个基于检测数据的计算模型。通过对不同隐形眼镜型号、尺寸的相应模具进行加工试验证明,该数学模型可以快速、精准地表达出微小对刀误差并进行修正,从而将隐形眼镜模具的超精密加工与检测进行有效集成,大大提高了模具的超精密加工质量和生产效率。     

数控加工技术在模具制造中的应用

随着科技的飞速发展,我国数控加工技术日益成熟,并广泛应用于机械加工制造业,特别是机械模具的制造中.模具制造有高精度要求,传统加工技术无法满足实际需求,在机械模具的制造中应用数控加工技术,能有效提升产品质量、加工精度及生产效率.通过简要介绍数控加工技术的应用现状,阐述在模具制造方面的优势,进一步分析该技术在模具制造中的有...     

基于逆向工程和快速成型的硅橡胶模具制造研究

介绍了以实物玩具为初始模型,利用逆向工程和快速成型技术制造该工艺品快速模具的方法.详细叙述了从模型数据采集、CAD建模、快速母模的制造、硅橡胶模具的制造直到产品试制的整个过程,并与传统的硅橡胶模具进行了对比,证实了这种基于逆向工程和快速原型制造技术的硅橡胶模具制造过程及思路的可行性和优越性.     

轮胎模具加工夹具的优化设计与力学分析

为解决轮胎模具加工制造中切割分块的问题,提高生产效率,设计了一副适用于轮胎模具加工的拼接式夹具,该夹具由转动装置、夹紧装置和固定装置3个部分组成,通过改变支撑架的安装位置和调整螺钉装夹不同尺寸的轮胎模具,可快速、准确地定位和装夹轮胎模具.简化夹具结构模型,建立力学分析模型,求解力学数学模型,优化夹具结构.并运用非线性有限元分析软件Abaqus进行受力分析,检验夹具加载荷时应力应变状态,验证了该夹具优化方案的合理性、实用性.该夹具应用于轮胎模具加工,提高生产率,降低劳动强度,增强企业竞争力,提高社会经济效益.     

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.