Simulation of service-oriented and distributed manufacturing systems

In this paper modeling and simulation is discussed in the context of distributed manufacturing systems (DiMS). The DiMS concept aims towards efficient and innovative collaboration that integrates design and development activities of manufacturing systems. A DiMS, described formally as a digital manufacturing system, is a competent basis for the modeling and simulation of manufacturing systems. The activities of the simulation model are described on the basis of a service-oriented approach in which content of the services is completely known. Micro, meso, and macro manufacturing levels are applied to the modeling and simulation. By means of these levels the hierarchy of the communication of the services is illustrated. An example is described in which modeling and simulation is used to proceed from ideas to efficiently operated manufacturing systems.     

Work design and analysis for space-based manufacturing: a case analysis of initial design issues

The purpose of the present research was to investigate the nature of potential manufacturing tasks humans may execute in a space environment. The success of space-based manufacturing (SBM) is suggested to be a precursor to permanent human presence in space. A working hypothesis for this study was that human work in the SBM environment would be substantially different from terrestrial manufacturing work. To investigate this hypothesis, a case analysis approach was developed that employed a function allocation and task analysis of a representative SBM process: the production of tailored industrial crystals. This research approach was chosen as the current state of engineering design for SBM is in the conceptual and early flow sheeting phases of a system life cycle. Results of the task analysis and function allocation process suggest response to corrective maintenance functions and to abnormal system conditions should be allocated to humans as opposed to automation. These results are discussed in relation to human factors engineering challenges associated with long-duration human presence in an SBM environment.     

Graphical and text-based design interfaces for parameter design of an I-beam,desk lamp,aircraft wing,and job shop manufacturing system

In this paper we describe four design optimization problems and corresponding design interfaces that have been developed to help assess the impact of fast, graphical interfaces for design space visualization and optimization. The design problems involve the design of an I-beam, desk lamp, aircraft wing, and job shop manufacturing system. The problems vary in size from 2 to 6 inputs and 2 to 7 outputs, where the outputs are formulated as either a multiobjective optimization problem or a constrained, single objective optimization problem. Graphical and text-based design interfaces have been developed for the I-beam and desk lamp problems, and two sets of graphical design interfaces have been developed for the aircraft wing and job shop design problems that vary in the number of input variables and analytical complexity, respectively. Response delays ranging from 0.0 to 1.5 s have been imposed in the interfaces to mimic computationally expensive analyses typical of complex engineering design problems, allowing us to study the impact of delay on user performance. In addition to describing each problem, we discuss the experimental methods that we use, including the experimental factors, performance measures, and protocol. The focus in this paper is to publicize and share our design interfaces as well as our insights with other researchers who are developing tools to support design space visualization and exploration.     

Simulation and graphical animation of advanced manufacturing systems

Automated production systems, known as Flexible Manufacturing Systems (FMS), offer a promising solution for the low productivity of mid-volume, mid-variety batch production. These systems consist of integrated machine modules and material handling equipment under computer control.This paper describes a general purpose discrete-event Flexible Manufacturing Systems Simulator (FMSSIM). The package is programmed in FORTRAN and is capable of simulating different configurations, material handling systems, and topologies including bidirectional tracks. The simulator checks blockage of routes due to interference of carts and simulates random failures and repairs of the various components in the system. The simulator provides the user with a wide range of priority rules to select from, and enables the user to define his own rules if required. The simulator produces reports on various vital system performance statistics and also displays the movement of parts through the system on a refreshed CRT. This simulator is a modular, user-oriented package which allows the designer to evaluate a wide range of systems with varied design parameters and select an efficient flexible manufacturing system. Some general trends in the behaviour of the flexible manufacturing systems are identified and guidelines for their design and operation are suggested.     

Interoperability of manufacturing applications using the Core Manufacturing Simulation Data (CMSD) standard information model

The goal of this paper is to propose an approach to enhance interoperability between manufacturing applications using the Core Manufacturing Simulation Data Information Model (CMSDIM) in order to streamline design and manufacturing activities throughout the product life cycle. To this end, a system framework required to facilitate such interoperability is first presented. The proposed approach, architecture, and developed translators are then illustrated and demonstrated using two separate case studies. The first case study facilitates design for manufacturing and assembly improvements for the development of new products, allowing for part of a discrete event simulation model of a downstream manufacturing and assembly process to be automatically generated from corresponding product assembly information contained in the lean design engineering software. Conceptual design and development of this case study, which extracts outputs from Design Profit™ lean design software and generates a corresponding discrete event simulation model in ProModel™ for a Nikon® L-100 Camera, is then discussed. The second case study demonstrates interoperability of three applications (order and inventory system, Gantt chart scheduler, and discrete event simulation) for a generic job shop operation. Using the considered case studies, this paper also details and demonstrates the benefits of interoperability enhancement using the CMSDIM, which is an important consideration in any product life cycle. Finally, we discuss how future research opportunities integrating additional manufacturing applications can be used to address intellectual challenges present in our current approach.     

Supporting management and maintenance of manufacturing knowledge in design automation systems

Many companies base their business strategy on customized products. To enable a high level of product adaptation in an engineer-to-order approach companies invest time and resources to develop design automation systems. Initially, when implementing a design automation system, the focus is on successfully developing a system that generates design variants based on different customer specifications (i.e. the execution of system embedded knowledge and system output). However, in the long run, two important aspects are the management and maintenance of the knowledge that governs the designs. Further, the increasing emphasis on deploying a holistic view of a product’s properties and functions implies an increasing number of life-cycle requirements. The knowledge to adapt the product to fulfil these requirements should also be used and consequently incorporated into the knowledge-base, allowing for correct decisions to be made. In a system for automated variant design, the implications on the product of these life-cycle requirements have to be expressed as algorithms, production rules and/or computational statements to be intertwined with the design calculations. The number of requirements can be significantly large, and the knowledge scattered over different application systems used for the realisation of the design automation system. This makes it difficult to manage and maintain the system as the product life-cycle environment changes and evolves.In this article, the focus is on the requirements related to manufacturing. For that, an approach for the modelling of manufacturing requirements, supporting both knowledge execution and information management, in systems for automated variant design is introduced. The approach has been applied and refined when developing a design automation system in cooperation with a company to demonstrate and verify the approach’s usability.     

Perturbation analysis for production control and optimization of manufacturing systems

We use stochastic fluid models (SFM) to capture the operation of threshold-based production control policies in manufacturing systems without resorting to detailed discrete event models. By applying infinitesimal perturbation analysis (IPA) to a SFM of a workcenter, we derive gradient estimators of throughput and buffer overflow metrics with respect to production control parameters. It is shown that these gradient estimators are unbiased and independent of distributional information of supply and service processes involved. In addition, based on the fact that they can be evaluated using data from the observed actual (discrete event) system, we use them as approximate gradient estimators in simple iterative schemes for adjusting thresholds (hedging points) on line seeking to optimize an objective function that trades off throughput and buffer overflow costs.     

Production decision support system for computerized manufacturing systems

The introduction of Computerized Manufacturing Systems (CMS) into the mid-volume manufacturing industry has been an important new step in the development of automated manufacturing. CMS's are computer-integrated systems which incorporate Direct Numerical Control (DNC) capabilities with automatic material handling to manufacture parts. Due to its complex nature, the task of production control in an CMS cannot rely on human effort alone. It is essential to develop a software package in the form of a Production Decision Support System (PDSS) to assist the production decision maker in operating this complex manufacturing facility.     

A decision support system for cellular manufacturing system design

With the growth of competitive pressure in the global markets, there has been an increase in demand in industry for cellular manufacturing systems (CMSs) in order to improve productivity and process flexibility. The design of CMSs for industrial applications is a complex and knowledge intensive process as it involves the consideration of many factors including production data and process characteristics. This paper describes the development and implementation of a decision support system for the feasibility and conceptual design of CMSs. The system is based on the knowledge-based system approach, and is able to make recommendations of system feasibility, cell formation techniques and cell types. A case study is also presented to demonstrate the capability of the decision support system.     

The application of manufacturing culture to the design of Asian region oriented machine tools

During the last years the demand for regionally and culturally harmonised machine design is increasingly on the agenda. The problem of localising products like machine tools instantly poses the question for new procedures that allow including the regional and cultural adaptations into the design processes of machine tool companies. How to transform the general insight into the necessity of culture- and region-adapted technologies and how to embed it into a design procedure comprising applicable design attributes is the crucial problem addressed. The paper shows in an exemplary way how ambiguous design attributes can eventually be embodied in a prototype design.     

浅析沙角A电厂5号机组FGD装置烟气系统的设计和运行

概述了广东省第一台300MW燃煤机组-沙角A电厂5号机组采用湿法脱硫投产后取得的成效,介绍了石灰石-石膏湿法脱硫装置烟气系统的设计情况,重点介绍烟气系统的运行情况,对存在的问题提出建议。     

An integrated form-feature-based design system for manufacturing

Much of the knowledge that is applied in or communicated between design and manufacturing activities is primarily shape based or shape indexed. Previous attempts to acquire and organize shape knowledge have been mostly concentrated on feature recognition from solid models, group technology (GT) coding schemes, and feature-based modeling. This paper presents the development of an efficient form-feature-based modeling system, and addresses the important issue of utilizing feature information for manufacturing, which has not been extensively discussed by previous work. In this paper we first present a Euler operator-based approach for efficient and effective form-feature encoding and manipulation in a feature-based design environment. Subsequently, a hybrid representation scheme called enhanced CSG tree of feature (ECTOF), which integrates feature model with solid model in a tree structure, is discussed. A feature interference resolution methodology to maintain the correct and consistent feature information in an ECTOF is also deliberated. Finally, we present a machinability-checking module, which employs global accessibility criteria to analyze a feature's machinability on a three-axis machining center. By developing feature interference resolving and machinability testing techniques and integrating with an efficient feature-based design system, this research makes the development of an integrated feature-based design and manufacturing system possible.     

A design of a controller as a component of a robotic manufacturing system

This paper specifies the functional design of a robot or machine tool controller suitable for inclusion in robotic manufacturing systems. The principle interest is the unmanned manufacturing cells which are being developed as major components of new manufacturing facilities. The functional specifications are motivated by recent experiences with the creation of a prototype cell for an open die forging process. There are two key technical design requirements. The first relates to the robot or machine tool being controlled. The controller must direct the machine actions, and, for unmanned operation, the controller must receive and process sensor information for process modification and for fault tolerance. The second relates to communication with the central cell computer (the host). The operation of an unmanned system requires a robot communication channel between the host and the controller; the controller must also respond to a variety of instructions transmitted from the host. Additional controller design requirements are imposed by economics. The proposed controller can be used today, and can develop in an evolutionary manner to meet the needs of future manufacturing systems. The evolutionary development is made possible by modular design, organized in a hierarchical manner.     

A decision analysis based system for formulating manufacturing strategy

Although a substantial number of decision and management science models of production management decisions have been developed, these models have not generally addressed the strategic framework of manufacturing, considered as an integrated pattern of decisions. They have usually been concerned with only one aspect of manufacturing strategy such as capacity or technology choice and have framed that choice using a single dimension of value such as cost. This study develops a comprehensive decision analysis model base which can be implemented as a DSS, to gain insight about the broader manufacturing strategy set. Decision trees, influence diagrams, Monte Carlo risk analysis and multiple criteria utility functions can contribute to a better understanding of and to decision support for manufacturing strategy formulation.     

Simulation aided design of organizational structures in manufacturing systems using structuring strategies

This paper presents a simulation aided approach for designing organizational structures in manufacturing systems. The approach is based on a detailed modeling and characterization of the forecasted order program, especially of elementary processes, activity networks and manufacturing orders. Under the use of the organization modeling system FORM, that has been developed at the ifab-Institute of Human and Industrial Engineering of the University of Karlsruhe, structuring strategies—e.g., a process-oriented strategy—can be applied in order to design organizational structures in manufacturing systems in a flexible and efficient way. Following that, a dynamical analysis of the created manufacturing structures can be carried out with the simulation tool FEMOS, that has also been developed at the ifab-Institute. The evaluation module of FEMOS enables to measure the designed solutions with the help of logistical—e.g., lead time degree—and organizational—e.g., degree of autonomy—key data. This evaluation is the basis for the identification of effective manufacturing systems and also of improvement potentialities. Finally, a case study is presented in this paper designing and analyzing different organizational structures of a manufacturing system where gear boxes and robot grip arms were manufactured.     

Cross-cultural analysis in online community research: A literature review

Cross-cultural online community research can support theoretical generalizability, increase methodological robustness and give insights into user online behavior. The objective of this paper is to review the existing literature on comparative cross-cultural online community research in order to investigate the current state of the literature, extract conceptual patterns and identify methodological and emergent issues. This will inform the development of the field, map out research delimiters, and set out guidelines for future research. The findings from the literature review demonstrated five key areas of methodological difficulty in cross-cultural online community comparative analysis; sampling form, country selection, number of cultures compared, participant type and interpretation of data. Key themes that emerged from the literature included the use of the nation state as a unit of culture, a lack of definition of the concept of online community, and the impact of current theory on cross-cultural online community analyses. Recommendations in the areas of methodology, definition and theory are provided. These findings should be of interest to both specific online community researchers, and those in other multidisciplinary fields where online communities are being used as a research environment.     

Stochastic cellular manufacturing system design subject to maximum acceptable risk level

In this study, a non-linear mathematical model is proposed to solve the stochastic cellular manufacturing system (CMS) design problem. The problem is observed in both machine and labor-intensive cells, where operation times are probabilistic in addition to uncertain customer demand. We assume that processing times and customer demand are normally distributed. The objective is to design a CMS with product families that are formed with most similar products and minimum number of cells and machines for a specified risk level. Various experiments are carried out to study the impact of risk level on CMS design. As the risk level increases, lower number of cells and product families are formed and average cell utilization increases. However, this leads to poor performance in cells, where standard deviations of capacity requirements are high. Later, the deterministic approach proposed by Suer, Huang, and Sripathi (2010) and the proposed stochastic model with various risk levels are compared. Both of the models’ results are simulated with Arena Simulation Software. Simulation is performed to validate models and assess the performance of designed CMSs with respect to following measures: cell utilization, WIP, total waiting time and total number waiting. Stochastic CMS design with 10% risk formed a better CMS in all of the performance measures according to the results obtained from simulation experiments.     

Lumber yield optimization software validation and performance review

Exhaustive search algorithms in simulation models are used by the secondary wood industry to find the optimal cutting pattern to cut lumber into dimension parts. Finding the optimum cut-up solution is of paramount importance to the industry for controlling product costs. For this purpose, the USDA Forest Service created the ROugh MIll RIP-first simulator (ROMI-RIP), a simulation model providing near optimum lumber cut-up solutions. However, ROMI-RIP was never truly validated nor was its performance directly proven. This study used data derived from a state-of-the-art rough mill to validate the program and to show its performance. Results show that ROMI-RIP outperformed the rough mill by more than 7% yield (71.1% versus 64.0%). Manufacturers of solid-wood products can realize significant yield gains by using ROMI-RIP. Additional benefits include lower production costs and significant savings in raw materials.     

Simulation modelling and analysis of part and tool flow control decisions in a flexible manufacturing system

This paper presents the details of a simulation study carried out for analyzing the impact of scheduling rules that control part launching and tool request selection decisions of a flexible manufacturing system (FMS) operating under tool movement along with part movement policy. Two different scenarios have been investigated with respect to the operation of FMS. In scenario 1, the facilities such as machines, tool transporter and part transporter are assumed to be continuously available without breakdowns, whereas in scenario 2, these facilities are prone to failures. For each of these scenarios, a discrete-event simulation model is developed for the purpose of experimentation. A number of scheduling rules are incorporated in the simulation models for the part launching and tool request selection decisions. The performance measures evaluated are mean flow time, mean tardiness, mean waiting time for tool and percentage of tardy parts. The results obtained through the simulation have been statistically analyzed. The best possible scheduling rule combinations for part launching and tool request selection have been identified for the chosen FMS.     

面向STEP-NC的数据处理与仿真平台研发

介绍了STEP-NC数据模型的基本特点，分析了数控程序中的信息类型，研究了从STEP-NC文件中直接提取制造信息的基本方法，建立了基于特征的数控加工几何仿真模型，并讨论了相应的实现方法和技术。最后在ST-Developer环境下开发了一个基本的STEP-NC支持平台，其基本功能包括STEP-NC文件的翻译、制造信息的提取、组织和图形化显示等，并能以工步为单位进行仿真。