Expert system support for environmental assessment of manufacturing products and facilities

The goal of environmentally conscious design for manufacturing is to select materials and processes that minimize environmental impact. This paper describes a general and uniform way to analyze the environmental impact of manufacturing based on the product decomposition, the materials used in the manufacturing processes, and the particular view of the environment. To accomplish this task, we developed a computer program, called EcoSys, that assists manufacturing engineers and environmental reviewers in assessing the environmental consequences of their manufacturing decisions.     

A STEP-based manufacturing information system to share flexible manufacturing resources data

The paper describes the design and implementation of a Manufacturing Information System as a solution to share and exchange manufacturing data. The Manufacturing Information System possesses relevant features for data sharing and exchanging, that are compliant to the standard ISO 10303, known as STEP¹. It is known that manufacturing planning and execution activities require data from machine-tools, robots, ASRSs², AGVs³ and, on the other hand, computer-based applications (CAM⁴, CAPP⁵ or PAC⁶) use proprietary formats to store flexible manufacturing resources data. The way the proprietary formats are built has lead to incompatibilities and interoperability problems among the applications. It is argued that by solving these problems a qualitative functional synergy will result during manufacturing planning and execution activities. The suggested solution is using a STEP-based information system, a server and a prototype client application. These three programs are implemented in Java classes to facilitate data sharing and exchanging of flexible manufacturing resources.This revised version was published in June 2005 with corrected page numbers.     

The steady-state region of attraction under linear feedback control: A numerical approach

In this paper, a numerical approach to operability analysis is developed. Based on the concept of the steady-state region of attraction, which indicates the initial operating conditions that can be driven to a given setpoint, this analysis helps design engineers assess whether a process can be effectively controlled by linear control systems. Using steady-state operating data that are generated with process simulators (such as ASPEN PLUS^®), the steady-state region of attraction are calculated by solving the proposed constrained nonlinear optimization problem. The objective function for the optimization problem is developed using the ellipsoid theory while the constraint functions are formulated from the complement set of the initially defined constraint set and the boundary of the available input space (AIS). Furthermore, as the solution of a nonlinear optimization problem generally depends on the initial starting point, a method of generating a set of ellipsoids in the hyperspace to start the calculation is also developed. The proposed constrained nonlinear optimization problem can be solved using numerical tools such as MATLAB^®. This analysis can be performed based on process flowsheets with process simulators and thus is useful in early stages of process design. The use of the proposed numerical framework is illustrated by a case study of a methyl acetate reactive distillation column.     

Generation of an adaptive simulation driven by product trajectories

The tracking of products trajectories involves major challenges in simulation generation and adaptation. Positioning techniques and technologies have become available and affordable to incorporate more deeply into workshop operations. We present our 2-year effort into developing a general framework in location and manufacturing applications. We demonstrate the features of the proposed applications using a case study, a synthetic flexible manufacturing environment, with product-driven policy, which enables the generation of a location data stream of product trajectories over the whole plant. These location data are mined and processed to reproduce the manufacturing system dynamics in an adaptive simulation scheme. This article proposes an original method for the generation of simulation models in discrete event systems. This method uses the product location data in the running system. The data stream of points (product ID, location, and time) is the starting point for the algorithm to generate a queuing network simulation model.     

A deadlock prevention approach for flexible manufacturing systems without complete siphon enumeration of their Petri net models

Siphons are very important in the analysis and control of deadlocks in a Petri net. However, it is quite time-consuming or even impossible to get the complete siphon enumeration of a Petri net. This paper focuses on the deadlock prevention problems in flexible manufacturing systems that are modeled with S⁴PR, a general class of Petri nets. The analysis of S⁴PR leads us to characterize deadlock situations in terms of insufficiently marked siphons. The method proposed in this paper is an iterative approach. At each iteration, a non-max-marked siphon is computed by solving a mixed integer linear programming problem. Then the siphon is max-marked through a P-invariant by adding a monitor place. This process is carried out until no non-max-marked siphon can be found in the net. As a result all the siphons in the net are max-controlled. Then the net becomes live. Without computing all the siphons, a monitor-based liveness-enforcing Petri net supervisor can be found with more permissive behavior. A number of flexible manufacturing examples are used to demonstrate the proposed methods.     

Simulation metamodel development using uniform design and neural networks for automated material handling systems in semiconductor wafer fabrication

Simulation is very time consuming, especially for complex and large scale manufacturing systems. The process of collecting adequate sample data places limitations on any analysis. This paper proposes to overcome the problem by developing a neural network simulation metamodel that requires only a comparably small training data set. In the training data set, the configuration of all input data is generated by uniform design and the corresponding output data are the result of simulation runs. A dispatching problem for a complex simulation model of an automated material handling system (AMHS) in semiconductor manufacturing is introduced as an example. In the example, there are 23 4-levels factors, resulting in a total of 4²³ possible configurations. However, by using the method proposed in this paper, only 28 configurations had to be simulated in order to collect the training data. The results show that the average prediction error was 3.12%. The proposed simulation metamodel is efficient and effective in solving a practical application.     

A straightforward method of measuring MPRT using LC test cells

Abstract— A simple method based on integration over time to measure motion‐picture response time (MPRT) has been developed. Liquid‐crystal response time (LCRT) alone cannot express the motion blur perceived by the observer; one must also take into account the transition between intermediate gray levels and the sample‐and‐hold effect. The method shows similar results to other previously reported methods based on temporal integration, while being simpler and more straightforward. Indeed, just monopixel test cells are required for measuring MPRT. This method can be used for comparison between different materials, alignments surfaces, or other manufacturing details with no need of fabricating the whole LCD structure. Nevertheless, the method could also be used for characterization of commercial displays with major changes. A comparison of MPRT values for three different liquid‐crystal materials is presented in this work. The behavior of the MPRT parameter in the case of an ideal liquid‐crystal material with an LCRT equal to zero has also been studied. The results obtained for this material have been used as a reference to establish comparisons with real materials.     

RFID-enabled real-time manufacturing information tracking infrastructure for extended enterprises

In extended enterprises, real-time manufacturing information tracking plays an important role and aims to provide the right information to the right person at the right time in the right format to achieve optimal production management among the involved enterprises. However, many enterprises are caused by lack of timely, accurate and consistent manufacturing data. The laggard information transfer flow and the unmatched information transfer method bring extended enterprises much more uncertainty and unknowingness. This paper proposes a RFID-enabled real-time manufacturing information tracking infrastructure (RTMITI) to address the real-time manufacturing data capturing and manufacturing information processing methods for extended enterprises. Following the proposed infrastructure, the traditional manufacturing resources such as employees, machines and materials are equipped with RFID devices (Readers and Tags) to build the real-time data capturing environment. In addition, a series of manufacturing information processing methods are established to calculate and track the real-time manufacturing information such as real-time manufacturing cost, progress, WIP (Work-in-progress) inventory etc. in parts/assemblies/products at machines/shop floors/enterprises/ extended enterprises levels. Finally, a case study is given to demonstrate the developed framework and corresponding methodologies.     

The implementation of neural network for semiconductor PECVD process

In semiconductor manufacturing, the monitoring system has been developed very excellently and can be used for comprehensively collecting the historical data of process information and quality characteristics of equipment. However, due to the high turnover rate of personnel and the great variance in manufacturing process, the previous control technique by using intuition and experience of engineers for manufacturing process parameter settings to achieve good product quality is no longer appropriate. Therefore, this research establishes a quality predictor for analyzing the relationship between manufacturing process parameter setting and final product quality in the plasma-enhanced chemical vapor deposition (PECVD) of semiconductor manufacturing by applying the back-propagation neural network (BPNN) algorithm and Taguchi method. The experimental data are categorized into 500 pieces of training data and 150 pieces of verifying data. The proposed analysis method for using in the PECVD process of semiconductor manufacturing is verified by comparing the predicted film thickness of SiO₂ and the predicted refractive index of silicon dioxide films with the measured data. According to the comparison result, the proposed model has an excellent prediction capability of final product quality and can be applied in process control for related manufacturing fields.     

A semantic knowledge management system for laminated composites

The engineering of laminated composite structures is a complex task for design engineers and manufacturers, requiring significant management of manufacturing process and materials information. Ontologies are becoming increasingly commonplace for semantically representing knowledge in a formal manner that facilitates sharing of rich information between people and applications. Moreover, ontologies can support first-order logic and reasoning by rule engines that enhance automation. To support the engineering of laminated composite structures, this work developed a novel Semantic LAminated Composites Knowledge management System (SLACKS) that is based on a suite of ontologies for laminated composites materials and design for manufacturing (DFM) and their integration into a previously developed engineering design framework. By leveraging information from CAD/FEA tools and materials data from online public databases, SLACKS uniquely enables software tools and people to interoperate, to improve communication and automate reasoning during the design process. With SLACKS, this paper shows the power of integrating relevant domains of the product life cycle, such as design, analysis, manufacturing and materials selection through the engineering case study of a wind turbine blade. The integration reveals a usable product-life-cycle knowledge tool that can facilitate efficient knowledge creation, retrieval and reuse from design inception to manufacturing of the product.     

面向产品全生命周期的标准件库研究与实现

设计数据是制造企业产品生命周期管理中的源头数据,设计数据的标准化、 规范化很大程度决定了整个PLM 系统的应用效果。据此,研究了在设计过程中物料信息的产 生及在PLM 系统中的传递过程以及设计工具软件与PLM 系统的单一数据源理论,提出了面 向产品全生命周期管理的标准件库系统的构建与实现方法;以及实现设计工具软件与PLM 系 统协同应用的方法。基于该理论及方法在SOLIDWORKS 的软件平台上开发实现了面向产品 全生命周期的标准件库系统,所开发系统已在某制造企业的设计部门得到应用,效果明显。     

An intelligent method for selecting optimal materials and its application

Material selection is associated with all design and manufacturing problems. This paper presents an intelligent method to deal with the materials selection problems wherein the design configurations, working conditions, as well as the design-relevant information are not precisely known. The presented method is applied to select optimal materials for robotic components at an early stage of design. A computing tool is developed in order to implement the method. Unlike other materials selection methods, the presented method does not require derivation of material indices, extraction of “if … then …” rules, or cumbersome inference calculations. However, like material index based selection method, it uses widely available material property charts as material-relevant information. This way the method is made more user-friendly and realistic.     

Optimum structure with homogeneous optimum cellular material for maximum fundamental frequency

Ultra-light cellular materials exhibit high stiffness/strength to weight ratios and bring opportunity for multifunctional performance. One of their potential applications is to build structure with optimum dynamic performance, which is extremely important for some structural parts in vehicle engineering and attracts a great attention. This paper presents a two-scale optimization method and aims at finding optimal configurations of macro structures and micro-structures of cellular material with maximum structural fundamental frequency. In this method macro and micro densities are introduced as independent design variables for macrostructure and microstructure. Optimizations at two scales are integrated into one system through homogenization theory and base material is distributed between the two scales automatically with optimization model. Microstructure of materials is assumed to be homogeneous at the macro scale to meet today’s manufacture practice and reduce manufacturing cost. Plane structure with homogeneous cellular material and perforated plate are studied. Numerical experiments validate the proposed method and computational model.     

材料测试表征和制备工艺数据库无代码生成系统

许多新材料研发企业的研发设计、制备以及测试表征分处于不同部门,导致材料制备工艺数据、测试表征数据以及研发设计数据呈离散化、碎片化状态,形成信息孤岛,且不能与材料计算有效地关联.开发一个通用的,能将材料测试表征、制备和服役数据深度融合的数据库系统,进而基于数据驱动方法,构建"成分-组织-工艺-性质"预测模型,有着非常重要的意义.然而,材料种类和体系众多,不同材料其测试表征方法以及制备方法多样性,给开发一种通用的融合材料测试表征和制备工艺的数据库系统带来很大挑战.基于此,我们首先参照CSTM材料基因工程数据通则,提出了一个材料测试表征和制备工艺数据库框架,进而基于无代码编程理念和语义UI模板,研发了一个通用的材料测试表征和制备工艺数据库无代码构建系统MatFusion.MatFusion能适用于不同的材料体系,帮助企业快速构建材料专用数据库,并在液态金属测试表征和制备工艺专用数据库的构建中得到了应用.     

Measurements of movements during highly repetitive industrial work

In the manufacturing industry highly repetitive movement patterns in the work situation are common. This work situation is often the cause of pain in the neck-arm region. To measure these movement patterns a new method has been developed by registering acceleration during ordinary industrial work. Three small accelerometers were fastened horizontally, transversely and vertically in a small box at the wrist. The data were fed into a computer memory at the work site and analysed later. The method can be used during ordinary work in a factory causing no interference to the work.     

Modular membrane valves for universal integration within thermoplastic devices

While much research has been conducted on elastomeric valves within PDMS microfluidic devices, we rarely see scalable manufacturing processes for integrating such valves into rigid thermoplastic devices. Most thermoplastic materials do not share intrinsic bonding compatibility to flexible elastomer membranes, making it difficult to ensure leak-proof operation of such valves within thermoplastic devices. In order to overcome bonding compatibility issues, we propose decoupling the valve architecture from the fluidic routing device layers. This can be achieved by prefabricating modular valves via molding processes and subsequently inserting them into thermoplastic layers containing valve seats. Thermoplastic layers containing modular valves are then thermally bonded to thermoplastic layers containing the fluidic routing channels, resulting in leak-proof valve integration. At valve actuation pressures of approximately 60 kPa, the modular membrane valves seal fluidic channels operating at a flow rate of 100 µl min^?1. Modular valves that were incorporated into a concentration gradient generator demonstrated dynamically configurable fluid routing at a response frequency of 5 Hz. The integration of modular membrane valves is an effective solution to streamline and cost-down the manufacturing of hybrid elastomer–thermoplastic devices. As this solution does not rely on bonding compatibility between the elastomeric membranes and the thermoplastic device, it can be applied universally to solve integration issues for low-cost thermoplastic device fabrication.     

Run-to-run control and state estimation in high-mix semiconductor manufacturing

In the modeling and control of semiconductor manufacturing, the control engineer must be aware of all influences on the performance of each process. Upstream processes may affect the wafer substrate in a manner that alters performance in downstream operations, and the context within which a process is run may fundamentally change the way the process behaves. Incorporating these influences into a control method ultimately leads to better predictability and improved control performance. Control threads are a way of incorporating these effects into the control of a process by partitioning historical data into groups within which the deterministic sources of variation are uniform. However, if there are many products, which require many threads to be defined, there may be insufficient data to model each thread. This multi-product–multi-tool manufacturing environment (“high-mix”) requires advanced methodologies based on state estimation and recursive least squares. Several such approaches are compared in this paper based on simulation models for a high-mix fab.     

An architecture for an intelligent support system for design validation and manufacturing of aerospace components

This paper presents the architecture of a multi‐agent system that aims to support the design and manufacturing processes of composite material components for the aerospace, automobile, ship and other industries. The major goals are to accelerate the design process while minimising cost; support users in selecting the optimum material in terms of its properties, cost and environmental impact; and enhance the efficiency of the component manufacturing phase by extending the decision support capabilities of the existing real‐time monitoring software. An important requirement for achieving these objectives is to enable the more efficient utilisation of existing distributed information on composite materials. To this end, state‐of‐the‐art advances in metadata concepts were adopted and extended. By implementing metadata structures for each data category available, the searching and retrieval mechanisms are improved both in terms of speed and usage. In addition, large amounts of knowledge about the design and manufacturing processes themselves are incorporated into a multi‐agent environment in order to enhance the ability to support the user groups involved in the various stages of component design and manufacturing. In order to present the system architecture here, an example from the aerospace industry has been used.