基于灰自助模型的气压动态测量结果评估方法

通过融合灰色模型GM(1,1)、Bootstrap方法以及不确定度评定理论,建立了气压动态测量结果的灰自助评估模型GBM(1,1),并选取估计真值、估计区间和平均不确定度等参数描述其估计结果。实验结果表明,GBM(1,1)模型融合了灰色模型GM(1,1)和Bootstrap方法的优势,可以准确模拟动态测量数据的概率分布,并跟踪动态测量过程中被测量的变化趋势,其估计误差最大值和平均值均小于原始数据的测量误差最大值和平均值。区间估计的可靠度高于96%,估计区间能够较完整地包络被测量的动态波动范围,由此证明GBM(1,1)模型能够提高气压测量精度,并可对动态测量结果的不确定度做出准确评估。     

基于Hertz接触理论的深沟球轴承滑动摩擦生热动力学仿真

通过ANSYS/LS-DYNA建立了深沟球轴承的多体接触动力学有限元模型,利用基于赫兹弹性接触理论的椭圆接触区域滑动模型,计算滚珠与滚道间的差动摩擦生热,对深沟球轴承的滑动摩擦升温进行了动态仿真。以6208深沟球轴承为例,轴承温度场的分布结果与实际情况较为吻合,表明仿真模型能较为准确地反映轴承的温升及分布情况。     

基于灰自助GBM(1,1)的滚动轴承摩擦力矩不确定性的动态预报方法

针对滚动轴承摩擦力矩变异过程的不确定性,通过融合灰预测模型GM(1,1)、自助原理以及扩展不确定度的概念,在乏信息条件下,建立了滚动轴承摩擦力矩不确定性的动态灰自助预报模型GBM(1,1),该模型可以由小样本数据预报大量数据,进而得到摩擦力矩的概率分布,获得给定置信水平下滚动轴承摩擦力矩的动态不确定度。通过试验研究,验证了该模型的正确性与有效性。     

深沟球轴承振动性能不确定性评估的数学模型实验研究

深沟球轴承是旋转器械的关键部件,其振动性能直接影响着与之配套主机的工作稳定性与可靠性。由于深沟球轴承振动性能概率分布与趋势先验信息的缺乏,而使得统计分析难以进行。为此,通过融合模糊理论和范数方法,作者提出了深沟球轴承振动性能不确定性的模糊数学评估方法,可以在概率分布和趋势未知的条件下揭示深沟球轴承振动性能的变异程度,及时发现潜在故障,采取维修及更换措施,降低事故发生率,从而最大限度地减少经济损失。本文对某型号深沟球轴承振动加速度时间序列的实验研究,证明了该方法的正确性与有效性。     

球轴承轴向承载能力研究

针对球轴承额定轴向载荷无精确数据的现状,给出一种基于Hertz接触理论的球轴承轴向承载分析方法。以深沟球轴承6000为实例进行理论计算,并用ANSYS软件对深沟球轴承6000极限轴向承载状况进行有限元仿真,验证理论分析的正确性。根据所给理论对球轴承轴向承载能力的主要影响参数进行分析,得出轴承包角、初始接触角与轴承轴向承载能力的关系,指出可用调整包角与初始接触角的办法提高轴向承载能力。研究结论可为生产实际中球轴承轴向额定承载能力的确定以及球轴承的结构优化设计提供参考。     

滚动轴承噪声的灰自助动态评估

以灰预报和自助再抽样方法为基础,提出灰自助动态评估模型,用于评估滚动轴承的噪声。该模型用动态不确定度、估计区间、估计真值、平均不确定度、平均真值和趋势项测度6个参数,全面描述滚动轴承噪声的基本特征。计算机仿真和工程试验表明,该模型对随机变量的概率分布与趋势项的类型没有任何要求,在平均不确定度为最小的条件下,可有效地分离出趋势项,评估的可信度达到100%。     

沟道形状误差对深沟球轴承振动和噪音的影响

针对深沟球轴承振动及噪音的产生原因以及沟道圆度和波纹度对振动和噪音的影响程度进行分析,为轴承在加工过程中减少振动及噪音提供参考。     

基于GBM(1,1)的大型滚动轴承摩擦力矩动态评估与预报

利用基于灰预报和自助再抽样建立的动态评估模型GBM（1,1）,对大型滚动轴承摩擦力矩进行分析研究,GBM（1,1）模型对样本的概率分布和趋势项的类型没有任何要求,在平均不确定度为最小情况下,可有效分离趋势项。该模型利用估计真值、估计区间和动态不确定度3个指标对滚动轴承的摩擦力矩基本特征进行全面描述。     

低噪声深沟球轴承仿真分析

在深沟球轴承动力学分析基础上,建立了低噪声深沟球轴承动态性能仿真数学模型,利用ADAMS多体动力学分析软件,开发了低噪声深沟球轴承仿真分析软件,对6205型低噪声深沟球轴承进行了仿真分析,探究了轴承径向游隙,内、外沟曲率半径系数,保持架兜孔引导间隙,保持架偏心距,轴向、径向载荷以及转速等参数对轴承振动的影响,结果表明:轴承径向游隙,内、外沟曲率半径系数对轴承本底振动有较大影响;合理的保持架兜孔形状以及兜孔半径均可减小轴承振动;施加一定的轴向载荷能够有效减小轴承振动,提高轴承寿命。     

低噪声深沟球轴承CAD系统

综合考虑现有滚动轴承振动与噪声的研究成果,研制出低噪声深沟球轴承CAD系统。本系统基于AutoCAD2000平台,在ObjectARX和Visual C 6．0开发环境中,采用面向对象技术的设计方法,可以提高低噪声深沟球轴承的设计质量与效率。     

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.     

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....     

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.     

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.