A multiattribute spreadsheet model for manufacturing technology justification

This paper presents a multiattribute spreadsheet models for the justification of manufacturing technology. The model includes interactive macro modules for AHP, Utility Model, and System Value Model.     

Using an electronic spreadsheet to analyze manufacturing flow systems

Contemporary use of electronic spreadsheets has centered on financial- and accounting-type analysis. Models are described in this paper that facilitate the use of an electronic spreadsheet for analyzing the flow of work in process through manufacturing system. It is shown that the spreadsheet-modeled analytic approach works best for the flow shop configuration: however, some job shop deviations can be considered. Stochastic elements must be approximated, but results are surprisingly close to those that come from the same system modeled with FORTRAN-based languages such as SLAM or INSIGHT. [A. A. Pritsker & C. D. Pegden, Introduction to Simulation and SLAM. Halsted Press, New York (1979); S. D. Roberts, Simulation Modeling and Analysis with INSIGHT. Regenstrief Institute for Health Care, Indianapolis (1982).] The advantages, limitations and assumptions of spreadsheet simulation and analysis models are discussed at length.     

Performance evaluation for manufacturing systems under control-limit maintenance policy

Maintenance decision-making in large manufacturing systems is complex as it requires the integration of various information. A control-limit policy is popular in practice, where maintenance is carried out when the degradation state of a machine reaches a threshold value. In this paper, by developing a framework based on discrete-time Markov chain models, we evaluate the system performance under the control-limit policy, in manufacturing systems that consist of multi-state machines and intermediate buffers. An exact analysis is performed for a two-machine-one-buffer system and an approximation method based on system decomposition is developed for multi-stage systems. Both steady-state and transient performance is analyzed. Numerical examples are presented to demonstrate the accuracy of the proposed method and the impact of different parameters (e.g., buffer capacity, uncertainty in the maintenance duration) on the system performance.     

Performance evaluation of real-time decision-making architectures for computer-integrated manufacturing systems

A general method is proposed for the performance evaluation of a decision-making architecture for computer-integrated manufacturing systems. A decision-making architecture broadens the concept of a control architecture by integrating control, communication and database functions. A modular modeling methodology is developed that captures these features and is applicable to an arbitrary computer-integrated manufacturing architecture. The model is based on generalized stochastic Petri nets and leads to a quantitative evaluation of such performance measures as response time, average utilization of a particular system component, average queue length, etc. The net result is a design tool that can be used to make tradeoffs among the system parameters.

The proposed technique is demonstrated using several real-time decision-making architectures. Several general conclusions are drawn from this investigation. Finally, a Petri net model reduction method is presented for this problem and used to compare the original performance evaluation results with those obtained from the simplified models.     

Performance evaluation and enhancement of multistage manufacturing systems with rework loops

The phenomena of machine failures, defects, multiple rework loops, etc., results in much difficulty in modeling rework systems, and therefore the performance analysis of such systems has been investigated limitedly in the past. We propose an analytical method for the performance evaluation of rework systems with unreliable machines and finite buffers. To characterize the rework flow in the system, a new 3M1B (three-machine and one-buffer) Markov model is first presented. Unlike previous models, it is capable of representing multiple rework loops, and the rework fraction of each loop is calculated based on the quality of material flow in the system. A decomposition method is then developed for multistage rework systems using the proposed 3M1B model as one of the building blocks. The experimental results demonstrate that the decomposition method provides accurate estimates of performance measures such as throughput and Work-In-Process (WIP). We have applied this method to several problems, such as the determination of the optimal inspection location and the identification of bottleneck machines in rework systems.     

A model for manufacturing systems simulation with a control dimension

The objective of this article is related to the potential improvement of computer simulation as applied to manufacturing systems. Through our contacts with the operational environment, we have observed that simulation is not used to its full potential. One remark is that existing tools are not adapted to modelling the decision process: they fall short of offering effective integration into the control process of production. Control is usually limited to scheduling and does not lend itself to practical application. In order to enhance the capabilities of computer simulation and make it more responsive to today’s industrial needs, we present a way of introducing such control into simulation by pursuing generic and applicable concepts. The core concepts that constitute the framework of our research are a global structure supporting the co-ordination and co-operation relations; a local structure presenting a typology of industrial control adapted to our needs; a control centre, the main concept used to introduce control into simulation. The modelling language used is UML and the model is implemented using the object-oriented language JAVA. An industrial application was carried out in the company Alcatel with the help of the Apollo platform.     

Industrial engineering spreadsheet applications from a manufacturing resource planning (MRP-II) system

This paper describes the MRP-II and distributed network initiatives undertaken at the Naval Air Rework Facility, Cherry Point, in the development of modular, integrated database management systems for material management, financial management, workload and work-in-process control, manufacturing scheduling and control, and inventory and kitting of parts back to production. The local area network and workstations using Zenith 248 PCs and bar coding data entry is described.

PC spreadsheet applications using the MRP-II database are illustrated. Production status, indirect cost management, and shop loading, using a special program called MAPPER to extract and format the data from the database, are just some of the examples to be described. “Lessons learned” are also related in the development of spreadsheet applications.     

Performance evaluation of client-server systems

A client-server system is a distributed system where a server station receives requests from its client stations, processes the requests and returns replies to the requesting stations. The authors consider client-server systems in which a set of workstations access a file server over a local area network. The systems are modelled by a class of stochastic Petri nets. The mean response time, the throughput and the parametric sensitivities are evaluated for a client-server system based on token ring network and a system based on CSMA/CD network. These models are different from the prevalent performance models of token ring or CSMA/CD network systems because of the message interdependencies introduced by the clients-server structure. An approximate analytic-numeric method rather than simulation is used to solve the models. The solution method and the accuracy of approximation are also discussed     

Performance evaluation of parallel systems

In this paper performance evaluation methodologies that have been applied to the analysis of parallel systems are reviewed together with the specific performance metrics. We concentrate on a few selected performance studies of parallel system components, i.e., processor, memory, interconnection network, input/output, and operating system. We demonstrate the utility of the performance evaluation methodologies for identification of system bottlenecks, performance forecasting, and future system design.     

Hierarchical control model for automated manufacturing systems

A mathematical model is presented to determine the hierarchical computer control requirements for a completely automated flexible manufacturing systems. This model can estimate the number and capacity of hierarchical computers needed to control a specified automated manufacturing system. The hierarchical control system is described by the major operating components common to all controlling computers and computer numerical controlled (CNC) machines: central processing unit, memory, input/output and communications. Each of these components is evaluated with respect to its operating speed and capacity. Costs are then determined as a function of the component's processing speed and capacity.A three-tier control system is examined. Starting with the CNC machines' speeds and capacities, each level of the computer hierarchical control system is modeled and related to the next tier by communication and data requirements. The physical machine layout required for a hierarchical control system is discussed. Part scheduling and process information requirements are also addressed. The model's utility is illustrated by an example using a typical manufacturing system.Optimization of this model is readily obtained using standard dynamic programming techniques. Being totally independent of any specific computer hardware technology, the model can be applied to present and future automated manufacturing systems.     

Multi-robot multi-operator collaborative assembly systems: a performance evaluation model

Journal of Intelligent Manufacturing - In the last decade, collaborative assembly systems (CAS) are becoming increasingly common due to their ability to merge the flexibility of a manual assembly...     

Performance evaluation of a single-stage two-product manufacturing system operating under pull-type control

This paper presents a model to analyze a manufacturing system that is operating under pull-type control. A Markovian polling model with finite queues is devised to represent the manufacturing system and studied under three cyclic service policies: exhaustive, gated, and a type of limited policy. These polling models are solved by two different methods: an exact approach that requires the complete characterization of the system as a Markov chain and a decomposition approach that reduces the size of the Markov chain. A set of numerical experiments show that the decomposition approach is quite accurate in estimating system performance measures.     

A model of computerization of manufacturing systems: an international study

This paper introduces a model of best practice in the computerization of manufacturing systems, by drawing on the practical experience of senior managers of both manufacturing and information management in Taiwan and the UK. The design used both qualitative and quantitative data analysis techniques to examine the implementation and integration of information systems support for manufacturing (ISSM). The investigation was conducted in three main phases. A series of qualitative case studies was conducted on the use of ISSM in 21 Taiwanese companies and 3 government organizations. Within-case and cross-case analysis showed that the six most important elements of ISSM implementation and integration are: the nature of manufacturing systems, ISSM and related software subsystems, barriers to ISSM, facilitators to ISSM, measured benefits from ISSM investment, and the level of ISSM integration. A preliminary development of a model of ISSM was then used to design a questionnaire for case studies analysis to examine ISSM in Taiwan and the UK. A comparison of ISSM in the two countries suggests that Taiwanese manufacturers have created platforms on which to build advanced manufacturing systems, are aware of the problems, and have plans to overcome them. UK firms had more experience with ISSM, and more organizations had achieved highly integrated manufacturing systems. Both countries appear to be moving toward similar designs for their enterprise resource planning and supply chain management systems.     

Flexibility in component manufacturing systems: evaluation framework and case study

Traditional component manufacturing systems have been optimized for either small scale craft production or for mass production of a small variety of high volume parts. Trends towards intermediate volumes and larger variety of parts have exposed the need for intelligently embedding flexibility in manufacturing systems and processes. The literature offers only few attempts to value component fabrication flexibility in a systematic way. In this article a 5-step framework for valuing flexibility and ranking of manufacturing processes under uncertainty is developed. A discrete time simulation is used to predict profit, remaining tool value and machine utilization as a function of three probabilistic demand and specification scenarios. A case study demonstrates the simulation and contrasts both a high volume (automotive) and a low volume (aerospace) market situation across six different processes ranging from punching to laser cutting. It is found that for intermediate, uncertain production volumes alternative manufacturing processes that embed flexibility carefully in one or more dimensions can outperform traditional processes that are either completely non-flexible (e.g., stamping) or completely flexible (e.g., laser cutting). It is also shown that flexibility in parts manufacturing is a complex topic because flexibility can be embedded in the parts themselves, in tooling or in the process parameters.     

A methodology for the evaluation of integrated manufacturing systems

The evaluation and selection of equipment for today's integrated manufacturing systems presents management with a complex multiattribute decision problems. This paper presents a spreadsheet based methodology that permits the incorporation of both monetary and non-monetary factors into the decision making process.     

Tolerance evaluation of minimum zone straightness using non-linear programming techniques: a spreadsheet approach

In general, non-linear optimization programs are formulated to evaluate the minimum zone straightness. This paper presents a spreadsheet approach that can be applied to determine the straightness errors of discrete data sampled from a continuous shape. The developed approach is easy to implement, and can obtain the minimum zone straightness based on the international standard, ANSI Y14.5M standard on geometric dimensioning and tolerancing. The primary goal of this spreadsheet implementation attempts to help reduce the possibility of making erroneous inspection decision, and then to precisely reflect the effect of inspection as early as possible for the purpose of quality control. An experimental study is conducted on examples taken from the literature and simulation data sets. Comparisons of the proposed approach against the existing methods in the previous studies are reported. Furthermore, the approach is demonstrated to be a viable tool for straightness verification in terms of the simulation data sets in which the theoretical straightness errors are known as a priori.     

Performance evaluation of fingerprint verification systems

This paper is concerned with the performance evaluation of fingerprint verification systems. After an initial classification of biometric testing initiatives, we explore both the theoretical and practical issues related to performance evaluation by presenting the outcome of the recent fingerprint verification competition (FVC2004). FVC2004 was organized by the authors of this work for the purpose of assessing the state-of-the-art in this challenging pattern recognition application and making available a new common benchmark for an unambiguous comparison of fingerprint-based biometric systems. FVC2004 is an independent, strongly supervised evaluation performed at the evaluators' site on evaluators' hardware. This allowed the test to be completely controlled and the computation times of different algorithms to be fairly compared. The experience and feedback received from previous, similar competitions (FVC2000 and FVC2002) allowed us to improve the organization and methodology of FVC2004 and to capture the attention of a significantly higher number of academic and commercial organizations (67 algorithms were submitted for FVC2004). A new, "light" competition category was included to estimate the loss of matching performance caused by imposing computational constraints. This paper discusses data collection and testing protocols, and includes a detailed analysis of the results. We introduce a simple but effective method for comparing algorithms at the score level, allowing us to isolate difficult cases (images) and to study error correlations and algorithm "fusion." The huge amount of information obtained, including a structured classification of the submitted algorithms on the basis of their features, makes it possible to better understand how current fingerprint recognition systems work and to delineate useful research directions for the future.     

Some kanban-controlled manufacturing systems: a first stabilityanalysis

The blockage/starvation patterns of known instability examples suggest using local demand information-which is precisely what is provided by the widely advocated kanban approach to flow control in manufacturing systems. Therefore, we have re-analyzed for stability the examples described in the 1990 Kumar-Seidman paper when modified by introducing kanban control. It is found that this does not ensure stability and, in fact, some interesting new instability phenomena arise. Counterintuitively, it is possible that increasing some reserve in a stable system may induce instability     

Modular production systems: a new manufacturing paradigm

It is well recognized that manufacturers of consumer goods throughout the world are facing major new demands, including shorter product life-cycles and increasing competition. In response, companies are restructuring and moving away from traditional process-centred work practices in favour of concurrent engineering methods. In particular, design for manufacture has gained widespread recognition as a means of reducing production costs and lead times. However, optimal design for manufacture is difficult to achieve using current-day work organization and business structures. An underlying problem is the lack of a scientific framework for production. To address this need, this paper proposes a radical and far-reaching new manufacturing paradigm based upon on building production systems from standardized modular machines. The manufacturing concept, termed modular production systems (MPS), is aimed specifically at hard low- to medium-technology consumer products, as typified by goods such as childrens toys and kitchen appliances. The rationale for MPS as a means of enabling concurrent product and production system design is put forward, and the long-term implications and work required to establish the concept are discussed.