基于粗糙集理论的航空发动机滑油光谱诊断专家系统知识获取方法研究

针对航空发动机滑油光谱诊断专家系统的知识获取问题,本文建立了基于粗糙集理论的航空发动机滑油光谱诊断专家系统知识获取模型。首先建立反映光谱元素浓度及元浓度梯度与发动机磨损故障之间关系的典型故障样本集;然后运用粗糙集理论的离散、约简及规则提取等算法,从大量的故障样本中自动获取知识规则,并将知识规则存储于专家系统知识库中;最后,建立推理机,运用一定的推理策略实现发动机磨损故障诊断。本文利用航空发动机实测的油样光谱数据对所建立的粗糙集知识获取方法,进行了实例验证。     

显微磨粒图像识别知识规则提取及其应用研究

针对新研制的多功能油液磨粒智能检测系统MIDCS中的磨粒图像识别问题,引入数据挖掘方法获取了磨粒图像识别的知识规则,实现对磨粒类别的智能识别。利用MIDCS系统获取实际航空发动机运行过程中由于滚动轴承磨损而产生的大量典型磨粒,基于图像分析方法提取16个磨粒特征参数,形成标准案例库;利用Weka软件的决策树算法自动提取知识规则,并对知识规则进行优化和简化;对所提取得到的知识规则进行验证和分析。结果表明,所提取的磨粒识别规则符合磨粒识别的统计规律,识别规则不仅简洁,而且具有很高的精度。基于Weka软件的规则提取方法大大提高了MIDCS系统的磨粒识别自动化和智能化水平,对于利用MIDCS进行航空发动机滚动轴承疲劳磨损故障诊断,具有重要的工程实用价值。     

一种航空发动机磨损故障模糊融合诊断方法

为提高航空发动机滚动轴承的磨损故障诊断的精度,综合利用多种油液分析方法的优点,提出一种航空发动机磨损故障的模糊融合诊断方法。首先,针对光谱分析、铁谱分析、颗粒计数分析、理化分析数据的各自特点,基于自定义隶属度函数对油液分析数据进行模糊化处理,从而得到表征光谱分析、铁谱分析、颗粒计数分析、理化分析数据的证据可信度和规则可信度,并得到综合可信度;然后利用D-S证据理论实现对多种油样分析数据的决策级融合诊断。将提出的融合诊断方法应用于航空发动机磨损故障诊断,利用某型发动机不同磨损时期的油液仿真分析数据对算法进行验证,证明了所提的方法具有很高的诊断精度和灵敏度。     

基于油液降噪信息的发动机磨损多特征分析研究

由于难以确定合适的油液检测数据处理方法,应用油液分析监测发动机磨损状态的有效性和针对性不高。为此,根据经小波包降噪的光谱数据和直读铁谱数据,在用新三线值法提取边界特征及用K-means聚类法获取质心特征的基础上,提出了质心-边界多特征分析方法,以确定发动机主要摩擦副的磨损状态。结果表明,多特征分析法比传统三线值法更详细、准确,使磨损状态的识别率提高一倍。信号的相关特征研究表明,活塞环摩擦副的磨损出现了异常,进一步证实了多特征分析的准确性和有效性。     

基于虚拟仪器和模糊SVM的航空发动机润滑系统故障诊断方法

利用虚拟仪器技术实现基于模糊支持向量机的航空发动机润滑系统故障诊断。通过对润滑油油液中磨损元素进行光谱识别与分析,提取故障诊断所需的特征参数作为支持向量机的学习样本,使用ActiveX技术在LabVIEW中调用MATLAB.m文件,完成对润滑系统的故障诊断,并比较了基于BP神经网络的诊断方法与模糊SVM故障诊断方法的诊断结果。结果表明:模糊SVM方法在故障诊断速度和诊断准确性方面都具有明显优势,其平均故障识别率达到95%以上。     

知识工程在油液监测故障诊断中的应用

针对目前油液监测故障诊断智能化、自动化遇到的困难，将知识工程的思想引入到油液监测中，并详细阐述了知识获取、知识表达、知识推理和知识利用在油液监测中的应用，最后将油液监测、知识工程、计算机技术结合起来建立了油液监测知识工程模型，为实现油液监测故障诊断自动化打下了基础。     

基于多维时间序列模型的内燃机磨损状态预测研究

现有的油液光谱数据预测方法仅考虑单一数据内部前后间的联系,忽视不同种类数据间的相互影响。多维时间序列模型能够将多种元素光谱数据融合起来同时进行建模,利用所建模型对光谱数据进行预测,提高预报精度。通过内燃机台架实验获得多种元素的光谱数据,选择典型的磨损元素Fe和Al、污染元素Si以及添加剂元素Mg作为分析元素,通过分析找出相关性较大的元素,利用多维时间序列模型对其进行预报,从而对内燃机的磨损状态进行准确判断。结果表明,将多维时间序列模型引入油液光谱数据预报能对内燃机的磨损状态进行准确预测。     

航空发动机油样光谱分析的PSO-LSSVM组合预测方法

油样光谱分析是航空发动机磨损状态监测与故障诊断的重要技术,基于光谱数据的航空发动机状态预测有利于发现航空发动机的早期磨损故障。根据光谱数据特征,选取AR模型、BP神经网络模型以及GM(1,1)预测模型作为基础模型,建立了基于最小二乘支持向量机的组合预测模型,同时,用粒子群算法对LSSVM的正则化参数以及核函数参数进行了优化。最后利用两组实际的航空发动机光谱分析数据对模型进行了验证,与基础模型的对比结果充分表明,提出的带粒子群优化的最小二乘支持向量机(the Least Squares Support Vector Machines with Particle SwarmOptimization-PSO-LSSVM)的非线性变权重组合预测模型具有更好的预测精度。     

基于粗糙集－集成神经网络的航空发动机磨损故障诊断方法

将粗糙集理论和神经网络相结合并应用到航空发动机磨损故障诊断中,依据属性的重要性和决策表的相容性,用自组织神经网络完成连续数据离散处理这一关键环节,采用粗糙集理论对征兆信息进行属性约简,获取征兆的主要特征,为神经网络结构简化和子神经网络的构成等奠定了基础,通过基于D-S证据理论的方法得到最终的融合结果。将该方法用于某型航空发动机的磨损故障诊断专家系统中,实验证明了该方法的有效性。     

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。     

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.     

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。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.     

OPTIMIZATION METHOD ON IMPELLER MERIDIONAL CONTOUR AND 3D BLADE

An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics (CFD) analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories: the meridional contour design variables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network (ANN) techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller performance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.     

5083H111轧制铝合金的低周疲劳行为

在室温下对5083H111轧制铝合金板三个典型方向——轧制方向(RD方向)、与轧制方向成45°角方向(MD方向)、垂直于轧制方向(TD方向)的试样进行了单轴对称应变控制的低调疲劳试验,研究了不同方向试样的循环变形行为和疲劳寿命差异。结果表明:铝合金板在三个方向上都表现出了明显的循环硬化特性,即在恒定的应变幅下,三个方向的响应应力幅均随着循环次数的增加而增大,并且外加应变幅越大,响应应力幅也越大;三个方向的低周疲劳ε-Nf曲线差别不明显;三参数幂函数寿命模型可以很好地预测5083H111铝合金的低周疲劳寿命。