熔融堆积成型系统中结构自动生成算法的研究

在熔融堆积成型系统中，零件原型的制作是靠热喷头挤出热熔丝逐层堆积成型的，因此，在零件原型的成过程中，支撑结构的生成是不可避免的。通过利用截面轮廓区域的自动识别、多边形区域的布尔运算以及多边形轮廓的OFFSET运算等几种关键算法，提出了SW2501快速成型系统中支撑结构的自动生成算法。该算法实际应用效果较好。     

基于熔融沉积成型技术的支撑算法设计

针对现有的熔融沉积成型支撑结构生成算法中耗材量大和结构不合理的缺陷,提出了一种支撑结构的生成算法。试验结果表明,该算法基于熔丝能够悬空的最大长度为判断标准来选择模型上的待支撑区域,能够减少打印耗材和打印时间。     

控制FDM成型制件误差的方法研究

快速制模是快速成型的主要应用之一,但成型件的精度难以达到快速制模对原型或型芯尺寸精度和表面精度的要求.系统分析了熔融堆积成型( FDM)工艺成型精度的影响因素,分析产生误差的根源及作用机理.针对FDM产生的误差,通过定性和定量分析,提出减小误差的途径和方法,并通过实例验证了解决翘曲变形和尺寸精度问题的方法,提高了原型的精度,对熔融堆积成型工艺精度的提高具有实际的参考价值.     

SLM快速成型中的支撑结构设计研究

在选择性激光熔融成型中,添加合理的支撑结构对保证具有复杂曲面零件的完整制造有着重要的作用。以最终成型零件的可行性及成型精度为目标,以相关实验验证为依据,对选择性熔融成型中支撑结构设计进行了研究。在STL模型的基础上,针对具有不同复杂曲面的零件,设计了按不同密集度分布的支撑,进行了系统的实验,并对不同参数支撑结构的实验结果进行了分析,得出了支撑密度、支撑当量半径、支撑半径补偿与零件表面倾斜角度间的关系,为选择性激光熔融成型中支撑结构的研究与运用提供理论依据。     

STL模型切片数据的优化技术研究

快速成型技术是一种基于离散/堆积成型原理的制造方法,它是在计算机的控制与管理下,根据零件的CAD模型,采用材料精确堆积的方法制造原型或零件的.目前在快速成型技术中,由于成型机的数据接口问题,通常在切片之前需要将CAD模型转换成STL模型,而STL模型的某些区域存在冗余的三角形,这些三角形的存在增加了切片时候的求交运算量.通过剔除部分狭长的钝角三角形,实现了对STL模型的合理优化,节省了文件存储空间和后续数据处理时间,具有一定的工程意义.     

熔融沉积快速成型的支撑优化工艺方法研究

熔融沉积成型技术(Fused deposition modeling,FDM)近年来在多个领域得到了广泛的应用,但制造过程中的悬空结构需要通过添加支撑用来支持悬空部分使成型过程顺利进行。而支撑结构不仅浪费成型材料,降低成型效率,最后在去除支撑结构时也会破坏制件的表面质量。因此从FDM技术的工艺特点出发,以减少使用支撑结构为目标,通过优化过程规划的工艺参数,提出一种针对熔融沉积成型技术的自适应支撑优化工艺方法。结果表明该方法有效地减少了支撑的使用量。     

FDM 工艺快速成型喷头内熔体的分析研究

熔融沉积快速成型,是利用热塑性材料的热熔性、粘接性特点,在计算机控制下根据实体模型进行层层堆积后成型。基于熔融沉积快速成型过程中熔体对成型制品的质量影响,对成型过程中熔体的流动性及热平衡进行数值分析,优化熔融快速成型工艺熔体参数,为喷头装置的设计提供依据,保证成型制品的质量。     

3D打印中支撑结构因素的技术分析

以FDM(熔融沉积成型)打印技术为例,通过实验分析的方式分析了在KISSlicer切片软件中支撑参数的设置与打印模型表面精度的关系;并通过这种实践经验值的方式研究了面对不同结构特点的打印模型,KISSlicer切片软件中支撑参数该如何设置,才能够将3D打印效果达到最优化。     

SW2501快速成形系统中支撑自动生成算法的研究

在SW2501快速成形系统中，零件原型的制作是靠热喷头挤出热熔丝逐层堆积成形的，这种成形过程，与FDM成形过程相类似。因此，在零件原型的堆积成形过程中，支撑结构的生成是不可避免的。提出一种自动生成支撑结构的软件算法，它通过利用截面轮廓区域的自动识别、多边形区域的布尔运算以及多边形轮廓的OFFSET运算等几种关键算法，介绍了SW2501快速成形系统中支撑结构的自动生成算法，该算法实际应用效果较好。     

基于切片软件新功能优化FDM成型的研究

随着熔融层积成型技术(FDM)近年来受到越来越多的关注,其成型工艺成为了制约其制件应用的重要因素之一。制件成型受诸多因素综合影响,且缺乏明确的量化评价标准。聚焦切片软件的新功能,重点针对挤出、支撑、层厚和填充等常见成型问题,分析了通过几项软件新功能对上述问题实现良好优化的可能性。经理论分析和实验验证,上述软件的新功能能有效提高制件的成型效果。     

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.