车辆发动机可靠性寿命试验数据的预测方法

针对车辆发动机可靠性寿命试验时间长的问题,提出采用灰色系统预测理论对车辆发动机可靠性寿命试验数据进行预测,建立了发动机可靠性寿命试验数据的无偏灰色预测GM(1,1)幂模型,通过采用试验数据序列与预测数据序列总体分布函数相等性检验方法确认无偏灰色预测GM(1,1)幂模型用于发动机可靠性寿命试验数据预测是可行的。算例结果表明,采用灰色理论预测方法预测发动机可靠性寿命试验数据并进行相关的分布函数参数估计有较高的精度,可达到缩短发动机可靠性寿命试验时间和节约试验费用目的。     

综合传动装置油液分析取样时刻预报方法

油液光谱分析是综合传动装置磨损状态监测的重要手段,基于油液分析样本数据量有限和样本值变化具有随机性的特点,选择灰色GM模型进行磨损量预测。根据油液分析数据变化规律,介绍综合传动装置灰色建模的具体步骤和方法,提出当磨损速率偏高时基于灰色建模进行加密取样时刻预报的方法。实验证明,基于灰色建模的加密取样时刻预报方法,能够及时扑捉综合传动装置异常磨损故障征兆,避免重大故障发生。     

滚动轴承磨损寿命数据的灰色预测

为了克服用概率方法对滚动轴承磨损寿命预测数据不足的缺陷,用滚动轴承磨损失效循环次数构造时间序列,提出应用灰色系统理论对少量已有的滚动轴承磨损寿命数据进行预测,扩充样本容量。研究表明利用灰色系统理论能在试验数据较少的情况下,建立灰色预测模型,来构造磨损寿命的数据序列,得到较精确的预测结果。利用此方法可以缩短试验的时间,节约试验的费用,对滚动轴承磨损寿命预测及可靠性评估是有益的。     

车辆动力传动系统故障诊断研究和应用

状态监测和故障诊断是防止机器出现重大事故的重要技术.本文介绍了车辆动力传动系统磨损类故障诊断的应用研究,重点介绍了作者研究的油液光谱分析界限值制定的方法和应用效果.     

车辆动力动系统故障诊断研究和应用

状态监测和故障诊断是防止机器出现重大事故的重要技术。本文介绍了车辆动力传动系统磨损类故障诊断的应用研究,重点介绍了作者研究的油液光谱分析界限值制定的方法和应用效果。     

基于信息熵和灰色系统的车辆变速箱故障诊断和磨损寿命预测

针对基于正态概率分布的润滑油中磨损元素预测容易出现误判的问题,提出基于最大信息熵的油液中各元素最无偏概率密度算法,得出车辆变速箱运行状态监测分界点;建立光谱分析元素浓度灰色系统模型,对车辆变速箱在整个寿命期间各组成元素浓度的变化情况进行预测,为车辆变速箱故障诊断和磨损寿命预测提供了新的方法和依据.     

车辆高里程NVH性能主观评价的灰色理论预测

针对车辆NVH性能主观评价试验往往难以获得完整生命周期评价数据的局限,尝试运用灰色系统理论分析并预测车辆高行驶里程下NVH主观评价数据。介绍灰色预测理论,并根据较少的试验数据,建立灰色GM(1,1)模型,用以预测车辆高行驶里程下NVH性能主观评价数据。理论分析和示例表明,模型精度较高,模型可用,基于灰色理论的车辆NVH主观评价数据的预测方法是可行的。     

重载齿轮系统油液分析数据灰色关联分析研究

油液分析是监测重载齿轮传动系统磨损状态的有效方法。通过油液分析方法获得磨粒浓度(WPC)、黏度、酸值和水分指标,构建磨粒浓度与润滑油理化指标的灰色关联方程及灰色关联动态矩阵,研究各监测时段理化指标与磨粒浓度的关联度动态变化趋势。研究表明,灰色关联动态矩阵能直观反映设备各时段的磨损状态与润滑油品质的动态关联情况,为判断在用润滑油是否满足设备的润滑状态提供理论支持,通过长期监测可建立科学合理油品补充周期。同时,可为铁谱分析中磨粒区分和设备磨损状态的判别提供依据。     

基于改进灰色预测模型的液压泵寿命预测

选取液压油的光谱分析数据作为液压泵的寿命特征信息,针对油液采样间隔不等间距的情况,研究非等间距灰色GM(1,1)模型。对建模数据背景值进行改造,建立改造背景值的非等间距灰色GM(1,1)模型,提高模型的预测精度。研究了油液分析阈值的制定方法,制定液压泵磨损金属元素含量和含量趋势值的阈值。运用改进背景值的非等间距灰色GM(1,1)模型对某型凿岩台车的液压泵进行寿命预测,预测精度达到95.78%。     

角接触轴承寿命的灰色预测分析

文中利用灰色预测研究方法对角接触轴承的寿命进行计算与分析。研究结果表明,灰色预测理论可以在原始实验数据不充分的情况下,通过建立模型构造角接触轴承磨损寿命数据序列,解决由于实验数据不足而造成的结果偏差。利用灰色预测研究方法对角接触轴承进行寿命测试,不但可以减少实验的经费,而且可以缩短试验时间,与传统的可靠性评估相比更具优势。     

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.