截止阀球面密封结构

介绍了截止阀阀瓣球面密封在密封效果、制造工艺和材料选用方面较锥面和平面的结构特点。给出了改进后的几种球面密封结构。     

带座外球面球轴承密封圈的改进

针对带座外球面球轴承密封圈压装过程中出现的问题，改进了密封圈的设计及结构：在密封圈外径唇部增设半圆形减压槽；加大密封圈外径尺寸，使密封圈外径与密封槽过盈配合；增大密封圈内径尺寸，使其接触过盈量适当；按带座外球面球轴承轻窄系列的密封槽尺寸确定密封圈外径唇部厚度。     

O形圈球面密封沟槽设计探讨

结合加工工艺和密封原理对O形圈在球面密封结构的沟槽设计进行了分析,提出了球面密封沟槽的设计方法,并在采油现场进行了球头灵活性和密封性能试验。结果表明,球头摆动灵活,密封性能可靠,验证了球面密封沟槽设计方法的正确性。     

高压作用下换热器管箱球面隔膜密封结构设计分析

通过换热器管箱球面隔膜密封结构几何尺寸关系和功能分析,研究球面隔膜变形的相关结构尺寸,推导了高压换热器管箱球面隔膜密封端口半径的条件式,求得了膜拱高、开口半径与补偿量关系并进行了讨论,公式简明易懂,应用方便。在此基础上,概括了关于球面隔膜结构功能的完整设计技术路线。分析表明,完善的球面隔膜密封设计应进一步考虑球面隔膜与其他因素的相互作用关系。指出管箱端口的密封依靠金属平垫和密封焊作为保证,并通过已运行多年的案例的主要计算过程进行了说明。     

水下连接器球面密封沟槽对O形圈密封性能的影响分析

一种可以实现水下连接角度补偿的球形法兰连接器采用O形圈作为主要的密封元件,位于球面上的密封槽通过影响O形圈的伸长率和压缩率来实现密封效果。槽宽b与槽深h是密封沟槽的主要尺寸,在满足球面沟槽设计准则的前提下,对O形圈球面密封沟槽的尺寸进行了设计计算。基于标准沟槽与球面沟槽体积大小一致的原则,确定了球面密封槽的具体尺寸。密封圈沟槽的尺寸设计主要改变了O形圈的压缩率大小。通过研究压缩率对O形圈密封效果的影响可以确定,17.6%左右的压缩率能够使密封圈的密封效果达到最佳。     

飞机燃油系统高压球面密封的故障分析与改进

针对飞机燃油系统补偿装置中使用的一种球面密封存在的低温下泄漏量大、耐冲击载荷差以及转动力矩太大的问题,对产品的密封材质和密封滑环的结构进行了改进.改进后产品的性能试验表明,产品的旋转力矩达到要求,产品在8 MPa压力下无渗漏,滑环形状无变化,唇边厚度在设计值允许的公差范围内,耐磨性显著提高.     

磨机双列调心球面滚子轴承的润滑与密封设计

讨论了大型磨机双列凋心球面滚子轴承的润滑方式选择及密封结构设计，提出了修正密封间隙的计算公式，为磨机滚动轴承的润滑密封设计提供了设计依据，经生产实践证明润滑方式和密封结构设计正确。     

高可靠的金属-塑料阀芯密封结构设计

为满足火箭发动机在性能上的要求，我所设计了一种耐高压的镶嵌非金属的金属阀芯密封结构，这种结构改进了传统的生产工艺，大大提高了工作效率，降低了生产成本。     

基于液压管接头接触面密封性能及螺纹受力分析的研究

针对60°液压管接头,通过分析锥面密封模型和多组不同弧面半径的球面密封模型,研究锥面密封的密封面应力分布和球面密封接触应力、密封宽度与弧面半径的变化规律,同时分析了液压管接头的连接螺纹取不同圈数时螺纹牙的受力情况。研究结果对液压管接头的设计具有一定指导作用。     

柔性钻杆O形圈球面密封性能研究

柔性钻杆已成为老井改造和增产提效的重要工具,为保障柔性钻杆球面密封的可靠性,对设计的一种O形圈球面密封结构开展数值模拟和试验研究。基于ANSYS有限元分析软件探究密封间隙、流体压力、转动角度以及有无挡环等因素对O形圈von Mises应力、接触应力、有效密封宽度等密封特性参数的影响。结果表明：流体压力与密封间隙存在耦合关系,流体压力越高要求密封间隙越小;往复转动会导致最大von Mises应力和最大接触应力升高,且随着密封间隙增大而影响加剧;挡环的安装可有效防止在密封间隙和流体压力较大时O形圈挤入缝隙。通过室内试验验证了O形圈球面密封结构的可靠性,为现场应用提供了理论依据和技术支撑。     

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。     

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.     

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....     

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.