Taguchi based fuzzy logic optimization of multiple quality characteristics in laser cutting of Duralumin sheet

Capability of laser cutting mainly depends on optical and thermal properties of work material. Highly reflective and thermally conductive Duralumin sheets are difficult-to-laser-cut. Application of Duralumin sheets in aeronautic and automotive industries due to its high strength to weight ratio demand narrow and complex cuts with high geometrical accuracy. The present paper experimentally investigates the laser cutting of Duralumin sheet with the aim to improve geometrical accuracy by simultaneously minimizing the kerf width and kerf deviations at top and bottom sides. A hybrid approach, obtained by combining robust parameter design methodology and Fuzzy logic theory has been applied to compute the fuzzy multi-response performance index. This performance index is further used for multi-objective optimization. The predicted optimum results have been verified by performing the confirmation tests. The confirmation tests show considerable reduction in kerf deviations at top and bottom sides.     

On the topological equivalence of some fuzzy flows near hyperbolic equilibria

The purpose of this work is to study fuzzy dynamical systems associated with deterministic systems. The Grobman-Hartman theorem states that, near hyperbolic equilibria, there exists a homeomorphism between the nonlinear system's trajectories and the linearized correspondent system's trajectories. That is, these systems are topologically equivalent. A theorem similar to Grobman-Hartman theorem to fuzzy flows is the main result in this article. For fuzzy flows obtained from each system it states that the nonlinear and the linearized are topologically equivalent.     

Fuzzy real valued lacunary I-convergent sequences

In this article, we introduce the concept of lacunary I-convergent sequence of fuzzy real numbers and study some basic properties.     

A note on a Carlson-type inequality for the Sugeno integral

In this short note, we present a general version of Carlson’s inequality for the Sugeno integral, which generalizes some recent results obtained by others.     

基于模糊C均值聚类的天文光谱特征线软离散化

连续数值属性离散化是天文光谱数据预处理中的主要研究内容之一。针对天文光谱特征线,提出了一种基于改进模糊C均值聚类的天文光谱特征线软离散化算法。该算法首先利用样本的密度值选取特征线的候选初始模糊聚类中心,有效地克服了对噪声数据敏感的缺陷;其次采用决策表中的相容性作为评判标准,动态的调节聚类参数,以达到优化的光谱特征线离散化效果;最后采用晚型星、类星体、高红移类星体SDSS天文光谱特征线数据集。实验验证了该算法具有较高的识别率,为天文光谱特征线数据预处理提供了一种新途径。     

Linear matrix differential dynamical systems with fuzzy matrices

In this paper, we investigate linear first-order fuzzy matrix differential dynamical systems where the coefficients matrix is described by a fuzzy matrix. We show some properties of the matrix differential dynamical systems, and their phase portraits are described by means of examples.     

Fuzzy control of original UPOs of unknown discrete chaotic systems

This paper presents a fuzzy algorithm for controlling original unstable periodic orbits of unknown discrete chaotic systems. In the modeling phase, only input–output data pairs provided from the true system are required. The fuzzy model is developed using Gaussian membership functions and consequent functions where the Levenberg–Marquardt computational algorithm is employed for the model parameters calculation. In the controller design phase, the L₂-stability criterion is used, which forms the basis of the main design principle. Simulation results are given to illustrate the effectiveness and control performance of the proposed method.     

Fuzzy multi-objective vendor selection under lean procurement

This paper investigates a fuzzy multi-objective vendor selection program under lean procurement based on cost minimization, delivery schedule violation minimization, and maximizing the quality level of the purchased quantity. Specifically, the paper incorporates the vendor production capacity uncertainty into the model to identify an appropriate selection policy for vendors under practical operating conditions. The use of a soft time-window mechanism for the vendor selection model enables decision makers to further incorporate a time based performance metric for vendor evaluation, based on the degree of urgency or need for a part. A solution algorithm using fuzzy AHP is proposed. The results of a numerical example suggest that decision makers prefer vendors who can promise tighter delivery schedules rather than on cost or quality. A sensitivity analysis of the soft time-window on the achievement of the lean procurement objectives is also conducted.     

基于Fuzzy-Rough-TOPSIS的工程项目投标风险评价模型研究

在工程项目招投标阶段,项目风险评价是建筑施工企业进行投标决策和作出项目选择的重要依据.基于理想化与主客观相结合的思想,提出了一种确定风险评价指标综合权重的方法;采用梯形模糊数处理模糊性信息,并将其与粗集理论和TOPSIS(a technique for order preference by similarity to ideal solution)方法相融合,建立了工程项目风险评价的Fuzzy-Rough-TOPSIS模型.实例运行表明,模型可操作性强,适用于多个项目的风险分析和比较,并能够在一定程度上克服以往模型存在的主观性强、应用条件限制严格等不足.     

区间数型多属性决策相对灰色关联分析方法及其应用

多属性决策时由于掌握的信息不充分,资料不全,加之问题本身的复杂性、不确定性以及人类思维的模糊性,其属性的精确值往往难以获取,常用区间数形式表示.针对基于"理想方案"的灰色关联分析方法存在的不足,根据TOPSIS法原理,提出一种同时考虑"理想方案"和"负理想方案"的区间数型多属性决策相对灰色关联分析法.通过一个实例说明了该方法的应用,并与其它方法进行了对比,得到的结果一致.方法同时考虑了"理想方案"和"负理想方案",概念清晰,数学推导严谨,评价值分辨率高,克服了仅考虑一种方案时排序的不相容问题,更具有客观性和合理性.