作业车间瓶颈簇识别方法

针对传统作业车间调度瓶颈识别方法划定多瓶颈候选集时缺乏科学的划分范围、划分层次和划分依据等问题,提出机器簇、瓶颈簇、主瓶颈簇及阶次的概念,建立了作业车间瓶颈簇的识别模型.考虑机器的主次之分和多维特征属性,基于聚类思想及多属性决策理论提出了作业车间瓶颈簇的识别方法.选择识别瓶颈的机器特征属性,采用免疫进化算法获得调度优化方案并计算机器的特征属性值;采用层次聚类法,获得不同距离下机器簇的集合及其树状结构图;基于理想解相似度顺序偏好法确定并比较机器簇的簇中心,识别出瓶颈簇和非瓶颈簇;对瓶颈簇的子簇依次进行比较,通过多次识别逐步确定出多阶主瓶颈簇集合.最后,采用24组作业车间调度问题标准算例,将所提方法与移动瓶颈识别法、正交试验识别法、机器负荷识别法等进行比较,证明了其可行性及优势.     

A particle swarm approach for grinding process optimization analysis

Optimization is necessary for the control of any process to achieve better product quality, high productivity with low cost. The grinding of silicon carbide is not an easy task due to its low fracture toughness, therefore making the material sensitive to cracking. The efficient grinding involves the optimal selection of operating parameters to maximize the material removal rate (MRR) while maintaining the required surface finish and limiting surface damage. In this work, optimization based on the available model has been carried out to obtain optimum parameters for silicon carbide grinding via particle swarm optimization (PSO) based on the objective of maximizing MRR with reference to surface finish and damage. Based on statistical analysis for various constraint values of surface roughness and number of flaws, simulation results obtained for this machining process for PSO are comparatively better to genetic algorithm (GA) approach. In addition, the post-optimal robustness of PSO has also been studied. From simulation results together with the proposed robustness measurement method, it has been shown that PSO is a convergent stable algorithm.     

A novel approach for correlative light electron microscopy analysis

Correlative light and electron microscopy (CLEM) is a multimodal technique of increasing utilization in functional, biochemical, and molecular biology. CLEM attempts to combine multidimensional information from the complementary fluorescence light microscopy (FLM) and electron microscopy (EM) techniques to bridge the various resolution gaps. Within this approach the very same cell/structure/event observed at level can be analyzed as well by FLM and EM. Unfortunately, these studies turned out to be extremely time consuming and are not suitable for statistical relevant data. Here, we describe a new CLEM method based on a robust specimen preparation protocol, optimized for cryosections (Tokuyasu method) and on an innovative image processing toolbox for a novel type of multimodal analysis. Main advantages obtained using the proposed CLEM method are: (1) hundred times more cells/structures/events that can be correlated in each single microscopy session; (2) three‐dimensional correlation between FLM and EM, obtained by means of ribbons of serial cryosections and electron tomography microscopy (ETM); (3) high rate of success for each CLEM experiment, obtained implementing protection of samples from physical damage and from loss of fluorescence; (4) compatibility with the classical immunogold and immunofluorescence labeling techniques. This method has been successfully validated for the correlative analysis of Russel Bodies subcellular compartments. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.     

Rapid structural mapping of ternary metallic alloy systems using the combinatorial approach and cluster analysis

We are developing a procedure for the quick identification of structural phases in thin film composition spread experiments which map large fractions of compositional phase diagrams of ternary metallic alloy systems. An in-house scanning x-ray microdiffractometer is used to obtain x-ray spectra from 273 different compositions on a single composition spread library. A cluster analysis software is then used to sort the spectra into groups in order to rapidly discover the distribution of phases on the ternary diagram. The most representative pattern of each group is then compared to a database of known structures to identify known phases. Using this method, the arduous analysis and classification of hundreds of spectra is reduced to a much shorter analysis of only a few spectra.     

布局问题的聚块算法

聚块布局法是解决布局问题的方法之一。本文对聚块布局法的关键点－聚块函数和模块组合进行了研究并提出了聚块算法,从而为模块组合和模块内布局物体位置的确定提供了一个定量的评价依据。     

A robust data treatment approach for fuel cells system analysis

This paper describes the implementation of a practical approach for fuel cells system data analysis. A number of data treatment techniques such as data management and treatment, data synchronization, and data reconciliation are introduced and discussed in order to solve the issues raised in the practical case. These techniques are integrated in a software environment which provides user a fast, efficient, and rational electrochemical investigation. The performance of the approach is illustrated using an industrial fuel cell stack test system.     

A framework for automated finite element analysis with an ontology-based approach

To obtain accurate and reliable results of finite element analysis (FEA) requires a high level of expertise and the full-scale physical context information, which are bottlenecks restricting the application of achievements of FEA in industry. This paper proposes an ontology-based framework including a hierarchy transfer approach and a three-stage automated finite element analysis method to solve these problems. The hierarchy transfer approach is proposed to create different transfer formats according to the data, information, and knowledge, to carry out the integration at different levels. The knowledge found in design and FEA theories is presented by ontology in order to uniformly describe the physical phenomenon with the same semantic meanings. This involves the development of a shared design and FEA ontology, as well as, specific application ontologies in the Ontology Web Language (OWL). The three-stage automated finite element analysis method is applied to mark up artifact in problem definition, to reuse domain knowledge in problem formulation, and to enable the automation of the FEM analysis process in the solution routine with the application of AI techniques. The feasibility and effectiveness of the framework and concepts are empirically validated by a case study.     

A reverse receptance approach for analysis of vibration of grooved plates

A reverse receptance approach is proposed to solve eigenvalues of a plate with two orthogonally connected through grooves, two parallel through grooves and two parallel internal grooves. The procedure is a modification of the well-known receptance method commonly used to study vibrations of combined structures. In the present paper, vibrations of rectangular plates with grooves in different sizes and boundary conditions are studied analytically to illustrate the approach. A through groove is simulated by a simply supported beam, while an internal groove is simulated by a free–free beam. The accuracy is evaluated by comparing the percent differences between the natural frequencies solved using the reverse receptance method and the standard finite element method.It is verified that the reverse receptance method with both force and moment connections at the interface of each plate–groove pair and with sufficient interaction points is adequate and accurate for solving vibration characteristics of a plate with either through or internal grooves. Parametric study reveals that the percent differences are directly proportional to the length, the width and the depth of the grooves on the plate. It is found that, for good accuracy, the groove width should not exceed 3.6% of the plate width, while the groove depth should not exceed half of the plate thickness. This report demonstrates the potential of reverse receptance concept in the engineering practice of machine design, as a simple numerical or analytical approach to study dynamics of structures with complex geometries.     

A semi-analytical approach for the geometrically nonlinear analysis of trapezoidal plates

This paper presents a semi-analytical approach for the geometrically nonlinear analysis of skew and trapezoidal plates subjected to out-of-plane loads. The thin elastic plate theory with nonlinear von Kármán strains is used for the nonlinear large deflection analysis of the plate. The solution of the governing nonlinear partial differential equations with variable coefficients is reduced to an iterative solution of nonlinear ordinary differential equations using the multi-term extended Kantorovich method. The geometry of the trapezoidal plate is mapped into a rectangular computational domain. Parallelogram (skew) plates are considered as a particular case of the general trapezoidal ones. The capabilities and convergence of the method are numerically examined through comparison with other semi-analytical and numerical methods and with finite element analyses. The applicability of the approach to the nonlinear large deflection analysis of skew and trapezoidal plates is demonstrated through various numerical examples. The numerical study focuses on combinations of geometry, loading and boundary conditions that are beyond the applicability of other semi-analytical methods.     

A non-parametric approach for linear system identification using principal component analysis

This paper considers the applications of principal component analysis (PCA) for signal-based linear system identification. Linear time-invariant (LTI) single-input-single-output (SISO) and multi-input-multi-output (MIMO) system frequency response function (FRF) estimation problems are formulated on the basis of the eigen-value decomposition (EVD) of the input–output measurement spectral correlation matrix. It is demonstrated that resulting algorithms for the SISO and MIMO cases are equivalent to that of the maximum likelihood (ML) and the total least squares (TLS) approaches respectively. Originating from the proposed FRF estimation scheme, a moving-segment EVD procedure is developed for SISO time-varying transfer function estimation. Based on the sensitivity of the time-domain PCA to delays/shifts between signals, an extended lagged-covariance-matrix approach is introduced for delay detection from time series.     

A novel non-probabilistic approach using interval analysis for robust design optimization

A technique for formulation of the objective and constraint functions with uncertainty plays a crucial role in robust design optimization. This paper presents the first application of interval methods for reformulating the robust optimization problem. Based on interval mathematics, the original real-valued objective and constraint functions are replaced with the interval-valued functions, which directly represent the upper and lower bounds of the new functions under uncertainty. The single objective function is converted into two objective functions for minimizing the mean value and the variation, and the constraint functions are reformulated with the acceptable robustness level, resulting in a bi-level mathematical model. Compared with other methods, this method is efficient and does not require presumed probability distribution of uncertain factors or gradient or continuous information of constraints. Two numerical examples are used to illustrate the validity and feasibility of the presented method.     

A modular approach to linear uncertainty analysis

This paper introduces a methodology to simplify the uncertainty analysis of large-scale problems where many outputs and/or inputs are of interest. The modular uncertainty technique presented here can be utilized to analyze the results spanning a wide range of engineering problems with constant sensitivities within parameter uncertainty bounds. The proposed modular approach provides the same results as the traditional propagation of errors methodology with fewer conceptual steps allowing for a relatively straightforward implementation of a comprehensive uncertainty analysis effort. The structure of the modular technique allows easy integration into most experimental/modeling programs or data acquisition systems. The proposed methodology also provides correlation information between all outputs, thus providing information not easily obtained using the traditional uncertainty process based on analyzing one data reduction equation (DRE)/model at a time. Finally, the paper presents a straightforward methodology to obtain the covariance matrix for the input variables using uncorrelated elemental sources of systematic uncertainties along with uncorrelated sources corresponding to random uncertainties.     

Reliability analysis and micromechanics: A coupled approach for composite failure prediction

This work aims at associating two classical approaches for the design of composite materials: first, reliability methods that allow to account for the various uncertainties involved in the composite materials behaviour and lead to a rational estimation of their reliability level; on the other hand, micromechanics that derive macroscopic constitutive laws from micromechanical features. Such approach relies on the introduction of variabilities defined at the microscale and on the investigation of their consequences on the material macroscopic response through an homogenization scheme. Precisely, we propose here a systematic treatment of variability which involves a strong link between micro- and macroscales and provides a more exhaustive analysis of the influence of uncertainties. The paper intends to explain the main steps of such coupling and demonstrate its interests for material engineering, especially for constitutive modelling and composite materials optimization. An application case is developed throughout on the failure of unidirectional carbon fibre-reinforced composites with a comparative analysis between experimental data and simulation results.     

A general method for analysis of planar mechanisms using a modular approach

A method that covers both kinematic, inverse dynamic, dynamic, and static analysis of any type of planar mechanism is presented. The method is based on a subdivision of the mechanism to be analyzed into kinematic chains that are categorized as either neutral or expansion modules. The neutral modules are the well known Assur Groups, characterized by the fact that they have no effect on the degree of freedom of the mechanism. On the contrary each expansion module increases the degree of freedom by one. The coordinates that correspond to the indeterminancy of the expansion modules may be identified as a set of independent coordinates for the subdivided mechanism and used in any type of analysis. The method as it is described in the present paper has been implemented in a menu-controlled PC computer program CADME. A number of practical observations concerning the implementation of a modular approach is made and discussed.     

An approach based on two-dimensional graph theory for structural cluster detection and its histopathological application

An approach based on graph theory is described for detecting clusters of cells in tissue specimens (two-dimensional space). With a set of discrete basic elements (cell nuclei) having several measurable features (area, surface, main and minor axis of best-fitting ellipses) a graph is defined as having attributes associated with edges. Different minimum spanning trees (MSTs) can be constructed using different weight functions on the attributes (attributed MST). Analysis of the MST and of an attributed MST by use of a decomposition function allows detection of image areas with similar local properties. These clusters, which are then clusters of the tree, describe, for example, partial growth in different directions in a case of a human fibrosarcoma assuming that tumour cell nuclei are homogeneous with respect to their configuration and size. The model allows the separation of clusters of tumour cells growing in different directions and the approximation of the different growth angles. This decomposition also allows us to create new (higher) orders of structure (cluster tree).     

A new approach for the analysis solution of dynamic systems containing fractional derivative

Fractional derivative models, which are used to describe the viscoelastic behavior of material, have received considerable attention. Thus it is necessary to put forward the analysis solutions of dynamic systems containing a fractional derivative. Although previously reported such kind of fractional calculus-based constitutive models, it only handles the particularity of rational number in part, has great limitation by reason of only handling with particular rational number field. Simultaneously, the former study has great unreliability by reason of using the complementary error function which can’t ensure uniform real number. In this paper, a new approach is proposed for an analytical scheme for dynamic system of a spring-mass-damper system of single-degree of freedom under general forcing conditions, whose damping is described by a fractional derivative of the order 0< α< 1 which can be both irrational number and rational number. The new approach combines the fractional Green’s function and Laplace transform of fractional derivative. Analytical examples of dynamic system under general forcing conditions obtained by means of this approach verify the feasibility very well with much higher reliability and universality.     

A new approach for bending analysis of thin circular plates with large deflection

This paper is concerned with bending analysis of an axisymmetric simply supported circular plate with large deflection. Based on the linear theory of thin plates, the incremental load technique is developed for solving the bending problem of a thin circular plate with large deflection. In the proposed method, the total applied load is divided into various small load steps. In each load step, the plate stress behavior is simplified to be linear. The incremental formulations are presented for the deflection and stresses of the plate when external loads increase. A numerical example is given to show simplicity and accuracy of the present method. It is found that the proposed method can be an alternative useful tool for engineering applications.     

A novel approach to the geometric feasibility analysis for fast assembly tool reasoning

A product assembly or disassembly is completed by means of proper tools. The selection of feasible tools is an important process in planning a complete assembly or disassembly sequence. A key tooling consideration in assembly or disassembly planning is to reason the available space for a tool application during the assembly or disassembly of a product. Currently, assembly tool reasoning about space mainly depends on simulation-based or user-interactive approaches because of its computational complexity. These approaches are inappropriate in dealing with various what-if scenarios regarding assembly or disassembly planning in a rapid product development. They also depend on users’ expertise or experience in assembly or disassembly. This paper presents a novel approach to the geometric feasibility analysis for fast assembly tool reasoning. Techniques described in this paper are advantageous not only in the aid of generating a complete assembly or disassembly plan but also in the efficient support of such systems as computer-aided assembly planning (CAAP), design for manufacturing (DFM), design for assembly (DFA), design for disassembly (DFD), and computer-aided tool selection (CATS).