深度学习与多信号融合在铣刀磨损状态识别中的研究

为精确地识别刀具磨损状态,提出了一种深度学习与多信号融合相结合的识别方法.以自编码网络为基础,构建了堆叠稀疏自编码网络.采集铣刀不同磨损状态下的力信号、振动信号及声发射信号,并对上述信号进行小波包分解以便获取能够表征铣刀磨损的时频域特征.利用无监督学习和有监督学习对堆叠稀疏自编码网络进行训练,建立了深度学习的铣刀磨损状态识别模型.研究结果表明,多信号融合的深度学习模型对铣刀磨损状态识别准确率达到94.44％.     

深度学习与多信号融合在铣刀磨损状态识别中的研究

为精确地识别刀具磨损状态,提出了一种深度学习与多信号融合相结合的识别方法.以自编码网络为基础,构建了堆叠稀疏自编码网络.采集铣刀不同磨损状态下的力信号、振动信号及声发射信号,并对上述信号进行小波包分解以便获取能够表征铣刀磨损的时频域特征.利用无监督学习和有监督学习对堆叠稀疏自编码网络进行训练,建立了深度学习的铣刀磨损状态识别模型.研究结果表明,多信号融合的深度学习模型对铣刀磨损状态识别准确率达到94.44％.     

基于BiLSTM的铣刀磨损状态监测模型

机械加工中刀具磨损退化直接影响工件质量和生产效率,在线监测刀具状态对于提高生产可靠性和降低刀具成本具有重要意义。为实现铣刀磨损状态在线监测,通过采集的主轴振动和主轴电机驱动电流作为监测信号;使用小波阈值降噪消除信号中的环境噪声干扰成分,并通过冗余提升小波变换保留信号的精确频率局部化信息,以提取更为丰富的频率特征;引入BiLSTM双向长短周期记忆网络对特征信号的时间信息进行编码,通过全连接层预测刀具磨损状态。通过铣刀的全寿命实验验证本文设计的铣刀磨损状态监测模型,结果表明,BiLSTM双向长短周期记忆网络可以有效评估铣刀磨损状态。     

基于小波分析和模糊控制理论的铣刀磨损监控方法

研制了一种铣刀磨损的监控方法.在该系统中信号采集采用声发射传感器,信号的特征提取采用小波分析的方法,将变换后的尺度系数和各个频段的小波系数作为特征,采用自行设计的Sugeno模糊控制系统进行状态识别,模糊控制系统的输出是刀具磨损的具体值.     

自适应随机共振算法的立铣刀磨损信号检测

在对刀具磨损信号的检测过程中,强噪加工环境使得所需特征信号显得非常微弱,给提取微弱特征信号带来了难题,基于此问题提出了利用自适应随机共振算法对立铣刀在磨损过程中产生的磨损信号进行检测,用加速度传感器和力传感器采集振动信号和切削力信号,再将提取的信号进行时频域的特征值提取,以此来分别建立遗传算法和粒子群算法优化的自适应随机共振模型,最后将这两种模型都用在对立铣刀的磨损检测中。实验结果表明,遗传算法和粒子群算法均可检测出立铣刀转动频率和刀齿切入频率,以及这两种频率下所对应的立铣刀磨损信号,为日后立铣刀磨损状态在线监测系统的建立奠定了基础。     

基于铣床主轴弯扭力学信号的铣刀磨损状态监测方法研究

为了及时检测出急剧磨损的铣刀,提高加工效率,保证工件精度和表面质量,设计了一种基于机床主轴弯矩与扭矩信号的铣刀磨损状态监测方法,利用主轴上的扭矩和弯矩传感器对加工过程中的刀具进行实时在线测量,并对采集到的数据进行处理。试验结果表明,将切削力信号融合提取特征作为输入信号,可以提高刀具磨损状态识别的准确性,能够直接和准确地反映刀具磨损状态。     

基于主轴电流信号多特征融合的刀具磨损状态监测

为实现在正常生产条件下进行刀具磨损的长期在线监测,提出了基于主轴电流信号和粒子群优化支持向量机模型(PSO-SVM)的刀具磨损状态间接监测方法。首先对数控机床主轴电机电流信号进行分析,将与刀具磨损相关的主轴电流信号多个特征参数和EMD能量熵进行特征融合作为输入特征向量;其次,通过粒子群寻优算法(PSO)对支持向量机模型(SVM)参数进行优化,建立基于主轴电流信号融合特征和PSO-SVM理论的刀具磨损状态识别模型;最后,通过实验采集某立式加工中心主轴在刀具不同磨损状态下电流信号进行验证,并与传统SVM模型、BP神经网络模型进行了对比分析。结果表明,所提出的方法具有较高的准确率和较好的泛化能力。能够实现正常生产条件下对刀具磨损的长期在线监测。     

特征融合与GA-SVM在刀具状态监测中的应用研究

为保证监测的准确性,刀具监控系统往往采用多个传感器进行监测并采集数据,导致监测成本的增加。通过对一个传感器的信号数据建立多个信号处理模型,将多个模型的特征进行融合,深度挖掘信号中所蕴含有关刀具磨损的敏感特征,提高监测的准确性,降低成本;同时针对将融合所得特征输入支持向量机(SVM)进行刀具磨损状态的识别时,常需要反复调整惩罚参数c和核函数g的问题,采用遗传算法(GA)对惩罚参数c和核函数g进行优化,减少了SVM模型的搭建时间,提高了SVM的识别准确率。     

考虑刀具磨损的数控加工误差的预测研究

将刀具磨损引起的误差通过建立的误差模型进行预测,是虚拟制造中的一项关键技术.通过分析影响刀具磨损的切削参数,针对硬表面的加工材料建立了基于相对切削时间的球头铣刀磨损模型,提出了虚拟制造环境下考虑球头铣刀磨损的复杂曲面加工误差预报方法.实验结果表明:该误差模型预报是有效的,并且为曲面加工误差预测、提高曲面加工精度和效率提供了理论依据.     

基于SOM和HMM结合的刀具磨损状态监测研究

针对端面铣刀磨损状态的识别问题,提出了基于自组织特征映射神经网络和隐马尔可夫模型结合的方法。该方法对铣削力信号进行预处理和相关特征提取,用自组织特征映射对信号特征矢量进行量化编码,所得码本作为隐马尔可夫模型的输入向量,分别训练三个不同磨损阶段的隐马尔可夫模型来对未知的刀具磨损状态进行监测与识别。实验结果表明,该方法能够对刀具磨损状态进行准确的识别,对自动化生产具有现实意义。     

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。     

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....     

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.