熔滴过渡光谱信号模式识别分类器的设计

以熔化极气体保护焊电弧光谱信号作为样本,设计了一种熔滴过渡模式识别分类器.首先对光谱信号进行预处理并抽取了多个关键性的特征参数,通过降维分析得到一组新的特征向量.随后建立了相应的识别函数和最小距离法分类器.最后利用检验样本对分类器的性能进行了检验和评价.判别结果表明,利用该分类器能够较好地对MIG焊和C02焊熔滴过渡类型进行自动识别,具有较高的准确性和识别精度,为实现熔化极气体保护焊熔滴过渡自动控制奠定了基础.     

Evaluation of thermal sprayed coating using ultrasonic inspection by means of bottom echo back reflection

Thermal spraying technique is widely used in various mechanical parts as a surface reforming technique. However, as demand to maintain superior mechanical performance in harsh operating environment increases, the need for non-destructive evaluation method for thermal spray coating becomes more important. For this purpose, we thinned the thickness of the thermal sprayed coating by abrasion with blasting and used ultrasonic inspection by means of bottom echo reflection for effective measurement of abrasion quantity in thermal sprayed coating. The results obtained are summarized as follows. When the thickness of thermal sprayed coating becomes thin, the echo height increases. This is because thermal sprayed coatings absorb ultrasonic energy. Ultrasonic energy absorbed by Al₂O₃ is smaller compared with Fe-13Cr coating. Thermal sprayed coatings submerged in water have a lower echo height compared with air. As mentioned above, the thermal sprayed coating thickness can be estimated using ultrasonic inspection by means of bottom echo back reflection.     

Non-destructive investigation of sluices using radar and ultrasonic impulse echo

Radar and ultrasonic impulse echo have been successfully applied for the assessment of two almost 100 year old sluices. The interior condition of the side walls has been investigated with radar enabling the detection of detachments of the faced brickwork as well as the determination of moisture content. With ultrasonic impulse echo working joints were found in the concrete slab of the sluice heads. The results of these investigations gathered comparative data to reduce the number of cores which had to be taken.     

Bayesian decision-based pattern recognition on spectrum signal of metal transfer modes

A software system of pattern recognition on spectrum signal of metal transfer mode has been developed using Visual Basic under Windows environment. On the basis of the coincidence relation between the spectrum signal and metal transfer mode, according to the geometrical pattern feature of the spectrum signal, several key characteristic parameters are extracted. The correspondent recognition function and a minimum distance classifier have been constructed based on Bayesian decision theory. The results show that using this system, the metal transfer mode of MIG, MAG, CO2 welding can be recognized automatically which provides the basis for automatically controlling of the metal gas arc welding metal transfer.     

Evaluation of temper embrittlement by ultrasonic attenuation

Research conducted up to the present time indicates the possibility of predicting the toughness of a material by utilizing ultrasonic attenuation characteristics. However, practically all of the cases concerned involve the investigation of changes in toughness brought about by making large changes in the microstructure of the material. However, the temper embrittlement encountered in Cr---Mo steels and the like are accompanied by large degradations in toughness with virtually no changes in microstructure and tensile strength. For this reason, it has been considered difficult to evaluate temper embrittlement based on ultrasonic attenuation characteristics. In the research reported here, sensitivity was enhanced by increasing the ultrasonic frequency (to 50 MHz) and the correlation between ultrasonic attenuation characteristics and temper embrittlement characteristics has been experimentally clarified.     

Training multilayered perceptrons for pattern recognition: a comparative study of four training algorithms

This paper presents an overview of four algorithms used for training multilayered perceptron (MLP) neural networks and the results of applying those algorithms to teach different MLPs to recognise control chart patterns and classify wood veneer defects. The algorithms studied are Backpropagation (BP), Quickprop (QP), Delta-Bar-Delta (DBD) and Extended-Delta-Bar-Delta (EDBD). The results show that, overall, BP was the best algorithm for the two applications tested.     

Assessment of modification level of hypoeu- tectic Al-Si alloys by pattern recognition of cooling curves

1 Introduction Due to their excellent castability and good mechanical properties, Al-Si alloys are the most important and most widely used casting aluminum alloys. A further increase in mechanical properties can be achieved by means of a modification treatment with Na or Sr. Without this treatment, the eutectic silicon crystallises into an acicular or lamellar morphology with poor properties; when a modifying element is added, it becomes a very fine and fibrous silicon network resulting in a…     

超声波探伤辊道的改进

HFW超声波探伤生产线主要是对热处理后的钢管进行探伤,保证合格钢管的正常生产。探伤机组是通过两组旋转辊道来保证钢管的匀速运送。为了适应不同产品规格,旋转辊道需要转到相应的角度,要求各组辊道的角度偏差小于正负0.5°。原设计万向轴连接的辊道无法满足辊道的角度偏差要求,通过拉杆式传动实现各组辊道的并列连接,进而消除了各组辊道的累积误差,使辊道的角度偏差控制到要求的标准范围内。     

Improving the evaluation sensitivity of an ultrasonic pulse echo technique using a neural network classifier

In this paper, the use of an artificial neural network (ANN) for classifying weak ultrasonic signals has been attempted. The limitations of using a single conventional parameter for signal detection and classification (namely peak amplitude alone) are highlighted. Use of a multi-parameter approach is suggested. The ANN used is a multi-layered, feedforward, error- backpropagation network. Results are compared with those of conventional approaches.     

模糊集合运算在冲压件工艺特征判断中的运用

针对目前的冲压工艺智能设计和特征识别的需要,提出了一种采用模糊集合运算的方法来进行冲压件工艺特征的判断。该方法适用于判断由多个因素的布尔关系决定的特征。运用本方法,首先将各个因素模糊化;然后选择合适的布尔运算和算子来进行模糊集合布尔运算;最后选择合适的λ进行λ截集,来实现工艺特征的判断。以悬臂和窄槽的判断为例,介绍了具体的计算过程。和以往的方法相比,该方法更加贴合工程实际,计算方便,灵活。     

Method of weld recognition based on textural feature matching

In this paper an automatic visual method of seam recognizing and seam tracking based on textural feature matching was proposed,in order to recognize the weld of multi-layer or multi-pass welding in which the weld is difficult to be recognized by conventional visual methods.This method focuses on the obvious difference of image textural feature between the weld region and the base metal region,as well as the similarity of the textural features along the welding direction.The method consists of the following steps: setting image template and choosing the edge region as ROI (region of interest),extracting the image textural feature of the template and the edge region,feature matching,and recognition of weld region.Experiment showed that the method proposed was effective for weld seam recognition in multi-layer welding.     

Molten salt phase diagram evaluation by pattern recognition:Part Ⅰ Divalent rare earth halide and alkali metal halide binary systems

At present CALPHAD (CALculation of PHAse Diagram) technique is not capable of predicting whether there exists intermediate compound, much less predicting the formulae, the number, and the melting congruence of intermediate compounds. To solve this problem, a new approach called the phase diagram evaluation by pattern recognition (PDEPR) was improved. The micro-parameters, such as the radius and the electronegativity of the element, were used as original features and then they were transformed and spanned to the different features in multi-dimensional space.Then a set of classifying functions were obtained to predict the information of intermediate compounds in REX2-AX systems (RE-rare earth element; A-Li, Na, K, Rb, and Cs; X F, Cl, Br, and 1). It is comparatively important for the design of materials.     

Molten salt phase diagram evaluation by pattern recognition：Part I Divalent rare earth halide and alkali metal halide binary systems

At present CALPHAD (CALculation of PHAse Diagram) technique is not capable of predicting whether there exists intermediate compound, much less predicting the formulae, the number, and the melting congruence of intermediate compounds. To solve this problem, a new approach called the phase diagram evaluation by pattern recognition (PDEPR) was improved. The micro-parameters, such as the radius and the electronegativity of the element, were used as original features and then they were transformed and spanned to the different features in multi-dimensional space. Then a set of classifying functions were obtained to predict the information of intermediate compounds in REX2-AX systems (RE-rare earth element; A--Li, Na, K, Rb, and Cs; X--F, CI, Br, and I). It is comparatively important for the design of materials.     

海洋平台构件单面焊焊缝超声检测根部回波的影响分析

海洋石油平台在建造过程中会大量使用只从一面焊接的管纵焊缝接头和TKY型管状接头.该类接头焊缝往往要求进行100％的超声检测,以确定焊缝中是否存在缺陷.受根部钝边角度和探头扫查面曲率变化的影响,焊缝根部的超声回波十分复杂.制作了含有不同倾角的根部钝边反射体试块,并对由根部反射面倾角变化引起的根部超声回波进行了分析.     

热电厂薄壁小径管的相控阵超声检测

通过在薄壁小径管上预制模拟缺陷,采用数字射线检测和相控阵超声检测技术对其进行检测比对,验证了相控阵超声检测工艺的有效性.结果表明:相控阵超声检测技术操作简便,缺陷检出率高,且可以通过积累图谱,为缺陷的定性提供参考依据.     

Evaluation of TiAI and 40Cr diffusion bonding quality using ultrasonic reflection spectrum

Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coeffwient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coeffwient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials.     

Evaluation of TiAl and 40Cr diffusion bonding quality using ultrasonic reflection spectrum

Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coefficient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coefficient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials.     

中厚板超声波在线自动探伤的研究与实践

针对中厚板手工探伤劳动强度大,漏探、误探率高的缺点,柳钢中板厂进行了多通道在线自动探伤的研究。通过采用多项先进技术,如增加探头数量、自动判伤功能、探头跟踪装置等,明显降低了漏探、误探率。     

固结磨料抛光垫的凸起图案对其加工性能的影响

抛光垫是化学机械抛光中的重要组成部分,其磨损均匀性能是影响加工后工件平面度的重要因素。本文比较了具有优化凸起图案的固结磨料抛光垫、凸起均布的固结磨料抛光垫和聚氨酯抛光垫的研磨抛光性能,结果表明:利用优化凸起图案的固结磨料抛光垫加工,可以得到更加优异且稳定的表面质量,材料去除效率远高于聚氨脂抛光垫游离磨料的加工方式。