基于集成神经网络的航空发动机故障诊断研究

针对航空发动机单一信息源故障诊断存在诊断效率低和准确率不高的问题,研究了基于油液和振动信息融合的集成神经网络的故障诊断方法,并将其应用到航空发动机的故障诊断中。以某型航空发动机为例,采用振动信息和油液信息融合诊断的思路,研究了集成神经网络故障诊断法在该发动机轴承故障中的应用,并结合具体数据对此诊断方法进行了验证。诊断结果表明,与传统的单一信息源故障诊断方法相比,集成神经网络故障诊断法诊断效率更高,可检测故障模式更多,误诊率更低。     

多源信息融合及其在齿轮泵故障诊断中的应用

针对齿轮泵故障信息的不确定性和模糊性,提出了一种多源信息融合的贝叶斯网络故障诊断方法。在探讨齿轮泵故障机理的基础上提取振动、流量和压力信号作为故障特征,构造故障贝叶斯网络,建立贝叶斯分类器进行多特征信息融合,利用最大后验概率准则判别故障类型。融合结果表明,该方法能够有效实现齿轮泵多种故障的诊断,具有广阔的应用前景。     

基于贝叶斯理论的汽轮发电机密封油系统故障诊断方法

在分析汽轮发电机密封油系统故障特点的基础上,提出了用贝叶斯理论进行故障诊断的方法,给出了求解故障诊断的数学表达式,充分利用样本的先验信息,建立了贝叶斯网络的推理方法,结合Leaky Noisy-OR模型来降低数据需求量,提高了诊断速度和效率。验证了该方法的有效性,实现了故障的前期预报和故障原因的快速诊断。     

基于本体的机械故障诊断贝叶斯网络

针对机械设备维护与故障诊断过程中的不确定性,提出了一种将本体语义表示与贝叶斯网络相结合的故障概率推理模型。从异构多源的维护诊断信息和非结构化的专家经验知识出发,建立语义知识模型并进行概率扩展。利用贝叶斯分类器实现异常工况识别,给出了基于最大可能解释(MPE)的故障概率推理算法,从而根据运行工况、故障征兆和证据信息推理获得故障诊断解释。将本体语义描述的精确性和贝叶斯网络的概率推理能力相结合,既实现了诊断领域知识的形式化描述与共享,又能在一定程度上消除诊断过程的不确定性。某凉水塔风机转子典型故障诊断实例表明,该模型具有较好的故障识别效果。     

基于本体的机械故障诊断贝叶斯网络

针对机械设备维护与故障诊断过程中的不确定性,提出了一种将本体语义表示与贝叶斯网络相结合的故障概率推理模型。从异构多源的维护诊断信息和非结构化的专家经验知识出发,建立语义知识模型并进行概率扩展。利用贝叶斯分类器实现异常工况识别,给出了基于最大可能解释(MPE)的故障概率推理算法,从而根据运行工况、故障征兆和证据信息推理获得故障诊断解释。将本体语义描述的精确性和贝叶斯网络的概率推理能力相结合,既实现了诊断领域知识的形式化描述与共享,又能在一定程度上消除诊断过程的不确定性。某凉水塔风机转子典型故障诊断实例表明,该模型具有较好的故障识别效果。     

贝叶斯网络数据细化的柴油发电机故障诊断

针对传统故障诊断方法在不确定问题诊断方面的不足,提出了基于贝叶斯网络的数据细化的柴油发电机故障诊断法。对柴油发电机转子的某些特定故障,结合专家知识确定转子特定状态下故障与振动频率、幅值及相关描述的依存关系,将获取的观测数据细化处理,利用结构学习,构建了基于贝叶斯网络的柴油发电机故障诊断模型,通过参数学习确定各节点的条件概率。实验结果表明,在已知信息具有模糊性和不完备性时,基于贝叶斯网络数据细化的故障诊断技术可明显提高诊断正确率。     

发动机故障诊断实训系统的构建与应用

为提高汽车发动机故障诊断实训效果,开发了汽车发动机故障诊断实训网络教学系统。系统集成了网络信息、通信、多媒体和数据库等多项先进技术,为电控发动机的故障检测与诊断提供了操作平台。学生通过该教学系统的学习训练,能够达到排除电控发动机真实故障的能力,极大地提升了发动机故障诊断实训教学水平。     

转子故障贝叶斯诊断网络的研究

将贝叶斯网络技术引入到转子故障诊断领域,旨在提高故障诊断中不确定信息的处理能力和推理质量;提出了用于转子故障诊断的一般网络框架,使诊断故障时既考虑了实际的运行工况,又考虑了现场的故障征兆,这符合专家的诊断思路;转子同频故障网络算例验证了其良好的识别效果。     

多特征信息融合的贝叶斯网络故障诊断方法研究

针对轴向柱塞泵故障特征的模糊性和不完备性特点,提出一种多特征信息融合与贝叶斯网络相结合的故障诊断方法。该方法从柱塞泵采集的振动信号中提取出频域和幅域的多个故障特征,并将这些特征当作来自多个不同传感器的多源信息。利用贝叶斯参数估计算法进行多特征信息融合。通过构造贝叶斯网络并建立贝叶斯分类器来简化融合后的结果,通过最大后验概率估计值的计算进行故障识别。经过轴向柱塞泵多故障模式的诊断实验,验证了该方法能够有效地实现柱塞泵柱塞松靴和脱靴故障的诊断。     

基于FMECA知识的故障诊断贝叶斯网络建模研究

为了构建具有较完备知识的贝叶斯网络诊断模型,提出了一种基于FMECA知识的故障诊断贝叶斯网络建模方法,该方法根据产品FMECA分析所得故障模式、故障原因、故障影响之间的因果关系构建贝叶斯网络拓扑结构,通过历史数据确定网络各节点的先验概率和条件概率分布,进而利用建立的贝叶斯网络进行故障诊断推理决策,最后通过某型飞机平视显示器的故障诊断贝叶斯网络建模及诊断实例,验证了方法的正确性及可行性。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

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...