Multi-response optimization using weighted principal component

Taguchi method is a very popular offline quality design. However, it cannot solve the multi-response problem which occurs often in today’s society. Research shows that the multi-response problem is still an issue with the Taguchi method. Researchers have tried to find a series of theories and methods in seeking a combination of factors/levels to achieve the situation of optimal multi-response instead of using engineers’ judgement to make a decision in the Taguchi method. In 1997, Su et al. submitted the multivariate method, and in 2000 Antony proposed principal component analysis (PCA), to solve this problem. But with the PCA method, there are still two main shortcomings. In this study, the weighted principal components (WPC) method is proposed to overcome these two shortcomings, and three cases in their papers will be illustrated and compared in the application of WPC method. The result shows that the WPC method offers significant improvements in quality.     

电容式电子清纱器系统的设计

针对目前电子清纱器主要以模拟电路为主,受元器件老化的影响较大,同时检测效率过低等问题,提出了将数字化电路应用到电子清纱器中的设计方法,以电容为传感元件,实现了一种电容式电子清纱器系统的设计。电容式电子清纱器系统以ARM STM32芯片为CPU,通过系统检测模块对纱线的质量进行了检测,将检测的数据传送给中段板,中段板将储存的数据向上传递给上位机,检测模块同时具有报警显示功能。检测模块通过RS-485总线与中段板进行实时通讯,以实现各指令的交换,并接收从上位机发送的配置信息。上位机可通过界面将实时数据进行直观的展现。通过对纱线的检测实验表明,该系统具有高精度、低功耗、实时性的特点,可广泛应用于纱线纺织工业,对纱线质量检测有着较高的水准。     

络筒张力控制系统研究

针对络筒工作过程中纱线张力的随机性和不稳定性,提出并分析了一种基于单片机的闭环式纱线张力控制系统,它可以实现纱线张力的实时控制,并具有结构简单、自动化程度高等特点。     

Experimental modeling and multi-objective optimization of traveling wire electrochemical spark machining (TW-ECSM) process

The present paper attempts to focus an application of a hybrid methodology comprising of Taguchi methodology (TM) coupled with response surface methodology (RSM) for modeling and TM coupled with weighted principal component (WPC) methodology for multiobjective optimization of a self developed traveling wire electro-chemical spark machining (TW-ECSM) process. First optimum level of input parameters is found using TM which is used as the central values in RSM to develop the second-order response model. For multiobjective optimization two quality characteristics surface roughness (R_a) and material removal rate (MRR), which are of opposite nature (R_a is the lower-the-better type, while MRR is the higher-the-better type), have been selected. The WPC is employed for the calculation of weight corresponding to each quality characteristic. The results indicate that the hybrid approaches applied for modeling and optimization of the TW-ECSM process are reasonable.     

Noise separation of the yarn tension signal on twister using FastICA

Some unknown noise will influence the wave appearance of the twist yarn tension signal in different factory environments or production processes. It is difficult to analyse the tension signal pattern and recognize unusual defects by the on-line yarn quality control system. In this paper, the independent component analysis (FastICA: fixed-point independent component analysis) is applied to separate the unknown noise signal from the unusual tension signal on the yarn twist machine. Different from the traditional low-pass filter (e.g., Butterworth filter), FastICA can not only successfully separate the noise with different types but also remain the main tension signal information. Firstly, FastICA algorithm is introduced, and then simulation experiments and on-line tests are carried out to evaluate the performance of this method and traditional low-pass filter.     

基于抖动特征的纱线检测方法研究

针对纺织生产中对运动纱线进行在线识别检测准确性低的问题,提出了一种用红外光电检测技术有效识别纱线的新方法,该方法的提m是基于柔性纱线运动时会以一定频率抖动,而且当纱线位于非均匀光场中,其抖动所导致的位置变换将会改变传感器接收的光信号强度.给出了检测方法流程,详细介绍了检测流程中的一些关键性模块设计方法并通过实验论证了其...     

锭子振动测试的数学模型研究

锭子在纱线卷绕时的振动问题不仅与锭子本身的振动有关,还与纱线卷绕时的纱线作用力有关,本文以纱线在高速卷绕时锭子的振动为研究对象。建立了锭子振动的力学模型,并以此为依据设计锭子振动测试装置。     

细纱机锭子在Solidworks中建模与虚拟装配探究

细纱机锭子是细纱机上加捻卷绕的主要部件之一,细纱锭子的设计水平与生产质量会对相应工序的生产能力及纱线的质量产生直接的影响。通过探讨细纱机锭子在Solidworks中建模与虚拟装配的整个过程,为优化细纱机锭子的结构设计,提高产品质量提供了一种易于掌握又切实可行的方法。     

基于多模态数据全信息的概率主成分分析故障检测研究

针对工业过程复杂的数据分布特性,本文提出了一种基于局部近邻标准化(LNS)的概率主成分分析(PPCA)故障检测方法(LNSPPCA)来解决由于过程数据的多模态特性和不确定性所引起的故障检测效果不理想问题.首先,通过LNS解决数据多模态问题,使标准化后数据尽可能的服从单一高斯分布,然后,使用PPCA方法从概率的角度对数据...     

反射式光电法纱线检测中信号影响因素分析

现今纺织业中机器纺织速度越来越快,传统的人眼识别速度已经不能满足纱线缺陷在线检测的需求,因而在纺织业中推进自动化检测变得尤为重要。针对纱线自动化在线检测中纱线疵点信号判别的需要,利用反射式光电检测原理通过搭建检测结构对纱线表面疵点进行采样并对采样样本特征进行分析。通过分析采样样本中疵点不同轴向尺寸、径向尺寸及灰度差异特征对输出产生的影响,为纱线疵点在线检测信号判断提供依据。经分析发现疵点轴向尺寸与采样样本响应时间呈线性关系,疵点径向尺寸及灰度差异与采样样本响应电压峰值呈线性关系。     

Optimisation of multiple responses for WEDM processes using weighted principal components

Taguchi method is widely used for optimisation of various processes. Using Taguchi method, the parametric settings can be optimised with respect to one performance characteristic (response) at a time, whereas wire electrical discharge machining (WEDM) processes require optimisation of multiple performance characteristics. Researchers have attempted several approaches but determination of the optimal process settings that can optimise multiple performance measures (responses) of WEDM operations still remains an important issue. In this paper, weighted principal component (WPC) method is used to optimise the multiple responses of WEDM processes. The results show that the WPC method offers significantly better overall quality than the other approaches.     

Homogenisation of the undulations of a single yarn. Applications to the modelling of the traction

Considering the yarn as the elementary constituent of fabric at the microscale, the mechanics of single-yarn motion and behaviour is investigated, whereby the impact of the thread undulations on the deformation mechanisms of the yarn are analysed. Considering that the yarn can be modelled as an undulated beam, a perturbation method is involved in order to set up the limit model of a straight yarn. Assuming the undulations to be quasi-periodical at a mesoscopic scale, a zoom is made on a period of undulation, so that the equilibrium problem of the yarn is embedded in a one undulation parameter (the ratio of the curvilinear length of a period to the projected length) series of problem. The limit behaviour for a vanishing undulation parameter is obtained, using the multiscale asymptotic expansion method. Equivalent mechanical rigidity in traction and flexion is further evaluated, the expressions of which reflect the actual undulation of the yarn, via the average over one period of trigonometric functions of the rotation field along the mean line of the beam. Traction curves for a single yarn in a woven structure are simulated, considering different initial shapes of the yarn, that do reflect the essential trends of the observed J-shaped curve behaviour of real fabric samples.     

优化变位卷绕系统及其PCC测控技术的研究

在分析研究化纤生产工艺和卷绕运动规律的基础上,提出了一种优化变位卷绕的卷绕成形原理、数学模型和实用方法。介绍了应用可编程计算机控制器(PCC)和变频调速等实现优化变位卷绕的测控技术和系统设计方案。能在高速纺丝情况下获得成形良好的大容量卷装,高速退绕时不会产生断头和脱圈,从而优化运行工况、改善产品质量、提高经济效益,对于提高现代化纤装备机电一体化的整体技术水平具有重要的理论价值和实用意义。     

Investigation of cross-sectional image analysis method to determine the blending ratio of polyester/cotton yarn

It has been considered as a great challenge to identify the blending ratio of polyester/cotton yarn in the field of textile industry. A new digital cross-sectional image processing method based on geometrical shape analysis is proposed to improve the measurement accuracy of polyester/cotton blend ratio. A self-developed microscope image capturing system is established to digitalise the cross-sectional images of polyester/cotton blended yarn. One set of image preprocessing algorithm is developed to conduct greyscale inversion, median filtering denoising and binarisation. The specially designed edge detection algorithm is used to identify the continuous profile of fibres. Finally, the roundness value of the cross-sectional fibre is calculated based on the proposed roundness algorithm, it can be used to identify the polyester/cotton fibres and calculate the blending ratio of them. Our experimental results show that the new digital analysis method proposed in this paper is feasible for the measurement of polyester/cotton blended ratio; therefore, it has a good application prospect in the field of textile quality control, including the development of new equipment, methods and standards.     

A multivariate surface roughness modeling and optimization under conditions of uncertainty

Correlated responses can be written in terms of principal component scores, but the uncertainty in the original responses will be transferred and will influence the behavior of the regression function. This paper presents a model building strategy that consider the multivariate uncertainty as weighting matrix for the principal components. The main objective is to increase the value of R² predicted to improve model’s explanation and optimization results. A case study of AISI 52100 hardened steel turning with Wiper tools was performed in a Central Composite Design with three-factors (cutting speed, feed rate and depth of cut) for a set of five correlated metrics (R_a, R_y, R_z, R_q and R_t). Results indicate that different modeling methods conduct approximately to the same predicted responses, nevertheless the response surface to Weighted Principal Component – case b – (WPC1^b) presented the highest predictability.     

Extraction of yarn positional information from three-dimensional CT image of textile fabric using a yarn model for its structure analysis

This paper proposes a novel method for analyzing a textile fabric structure to extract positional information regarding each yarn using three-dimensional X-ray computed tomography (3D CT) image. Positional relationship among the yarns can be reconstructed using the extracted yarn positional information. In this paper, a sequence of points on the center line of each yarn of the sample is defined as the yarn positional information, since the sequence can be regarded as the representative position of the yarn. The sequence is extracted by tracing the yarn. The yarn is traced by estimating the yarn center and direction and correlating the yarn part of the 3D CT image with a 3D yarn model, which is moved along the estimated yarn direction. The trajectory of the center of the yarn model corresponds to the positional information of the yarn. The application of the proposed method is shown by experimentally applying the proposed method to a 3D CT image of a double-layered woven fabric. Furthermore, the experimental results for a plain knitted fabric show that this method can be applied to even knitted fabrics.     

Thermo-viscoelasticity of a twisted yarn

A static analysis is given of the thermo-viscoelastic deformation of a twisted yarn, deformed further by increments of extension and twist. The yarn is assumed to conform to the Thwaites solid rod model. The filaments of the yarn are assumed to be linearly viscoelastic, thermorheologically simple and mechanically incompressible. These assumptions lead to an analytical solution, expressed in terms of Laplace transforms with respect to an “effective” time-scale. Expressions are derived for the axial force and torque in terms of the axial extension and twist, the expansivity of the filaments and their viscoelastic parameters.     

数控机床检测元件故障诊断及维修实例

位置检测元件是数控机床的重要组成部分,检测元件采用直接或间接的方法将数控机床的执行机构或工作台等设备的速度和位移检测出来,并发出反馈信号,与数控系统发出的信号指令相比较．构成闭环（半闲环）系统和补偿执行机构的位置误差,从而提高数控机床加工精度。本文阐述了数控机床检测元件的日常维护及注意事项,通过长期实践总结积累了位置检测元件常见的故障及维修实例。     

改进VPMCD方法在滚动轴承故障诊断中的应用

针对模式识别新方法VPMCD(variable predictive model based class discriminate)在参数估计过程中存在的缺陷,对VPMCD方法进行了改进,用主成分估计法代替原方法中的最小二乘法进行参数估计,消除了预测变量间存在多重线性相关性的影响,可以获得更加稳定的模型参数,从而提高模式识别的精度。采用局部特征尺度分解(LCD)方法对滚动轴承振动信号进行分解得到若干个单分量信号,提取各分量的近似熵组成故障特征向量作为改进VPMCD的输入,以改进VPMCD作为分类器对滚动轴承的工作状态和故障类型进行分类。对正常状态、外圈故障、内圈故障和滚动体故障四种不同工作状态和故障类型下的滚动轴承振动信号进行了分析,结果表明该方法有效。