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  • 标题:Multipolar synchronous material flow & process simulation in difussed manufacturing systems.
  • 作者:Cotet, Costel Emil ; Dragoi, George ; Abaza, Bogdan Felician
  • 期刊名称:Annals of DAAAM & Proceedings
  • 印刷版ISSN:1726-9679
  • 出版年度:2007
  • 期号:January
  • 语种:English
  • 出版社:DAAAM International Vienna
  • 摘要:Key words: multipolar synchronous simulation, process, material flow, diffused manufacturing systems, productivity.
  • 关键词:Algorithms;Manufacturing;Manufacturing processes;Simulation;Simulation methods

Multipolar synchronous material flow & process simulation in difussed manufacturing systems.


Cotet, Costel Emil ; Dragoi, George ; Abaza, Bogdan Felician 等


Abstract: We had applied in this paper our new algorithm integrating the process simulation using specialized CAM (Computer Aided Manufacturing) software in the material flow simulation on diffused manufacturing systems where are several work points of the same importance in the system. The result is a synchronous simulation model providing more accurate results. In order to optimize manufacturing systems architecture, finally, a multipolar distributed simulation composed of four individual simulations is successfully tested across platforms over the internet.

Key words: multipolar synchronous simulation, process, material flow, diffused manufacturing systems, productivity.

1. INTRODUCTION

As a result of our research in the last few years we determined that if we want to optimize the architecture of a VE usual material flow simulation is not enough (Cotet & al., 2004). One of the main problems is the difference between the algorithms for process and material flow island of simulation. This is the reason why we propose here a new tool, synchronous multipolar simulation, able to evaluate the performances of a VE as an integrated system. The synchronous multipolar simulation analysis is more then concatenating the results of isolated island of simulation. The flow concentrator as it results from the synchronous multipolar simulation may be any one of the concentrators of material flow manufacturing system simulation nodes but may also be a total different one.

2. FOCUS ON THE FIFTH ELEMENT

Five main elements must be defined in order to perform our simulation algorithm.

We define diffused manufacturing systems as architectures with more than two work points connected by transport & transfer systems and using deposits at local or system level (Cotet & Dragoi, 2003).

We agree here with the thesis that within the class of stochastic simulation models, one further distinction is necessary: simulations can be either terminating (sometimes called finite) or nonterminating in nature, with specific algorithms for each category (Sanchez, 2001).

We agree that virtual enterprises could be defined as ephemeral organizations in which several companies collaborate to produce a single product during a project cycle time (Tichkiewitch & al., 2006).

We define as multipolar distributed simulation the integrated monitoring system of more than two material flow simulations interconnected in VE architecture.

Last but not least we consider a material flow and process synchronous simulation the simulation of a model where at the level at the work point the process simulation is concomitant with the material flow simulation.

As reflected in this paper our present research is now focused on this fifth element.

[FIGURE 1 OMITTED]

We built the multipolar synchronous simulation algorithm starting from the multipolar simulation model for virtual enterprises developed in our UPB-PREMINV Research Centre (Cotet & al., 2004). During those previous researches we developed this preliminary model using SADT and tested it in our virtual enterprises oriented partnerships with industrial SMEs. The main improvement to this preliminary model is that in our new algorithm every work point process simulation will be related with the material flow simulation. Actually in this new approach at the level at the work point the process simulation is concomitant with the material flow simulation.

3. A THREE LEVEL ALGORITHM

Three levels of integration are defined in the multipolar synchronous simulation algorithm:

At the first level main parameters for the work points modeling in material flow simulation are provided form CAM simulations describing the manufacturing process (Lee, 1999). This way the material flow simulator is integrating the process simulation results at the level at the work point in order to provide a complete model of the manufacturing system.

At the second level the terminating simulation algorithm (mainly used in diffused related architectures) is applied for each manufacturing system of the virtual enterprise network.

At the third level the virtual enterprise material flow is simulated. In this model the work points are the terminating simulation models describing the virtual enterprise partners manufacturing systems material flows. At this level the complexity of synchronizing process and material flow simulation is higher then in concentrate manufacturing systems with a single work point. The stochastic laws describing the MTBF (mean down interval) and MTTR (mean repair time) for every work point for every industrial partner activating as a virtual enterprise network node must be corroborate with the laws describing the integrated multipolar model work points (describing the material flow at the level of each enterprise as well as for the entire virtual enterprise architecture). The first case study that allowed us to test our model was provided by one of our research projects implying four industrial partners working in a virtual enterprise environment.

[FIGURE 2 OMITTED]

4. LOCAL & MULTIPOLAR SYNCHRONOUS MODELS

In our case study four diffused manufacturing systems are implied. For each of those manufacturing systems synchronizing process and material flow simulation is based on modeling using two software solutions: CATIA and Witness.

At the end of this local synchronizing process the material flow simulation using Witness software as well as the CAM simulation allowed us to change some of the manufacturing cycles introducing stochastic distribution laws values for MTBF or MTTR adapted to each work point characteristics. In figure 2 is presented one of those manufacturing systems synchronous simulation models. Based on those four models we built then the multipolar model. In this model describing the manufacturing processes and the material flow of the entire virtual enterprise architecture the model of each manufacturing system acts like a work point. Based on the four local models stochastic laws are describing specific parameters characterizing the activity of each enterprise. For example taking into account that the flexible manufacturing system presented in figure 2 is producing two kinds of parts, the failed parts number for each type will be described by a Beta stochastic distribution law with specific parameters as one can see in figure 4. Because of specific parameters describing the activities performed by each manufacturing system acting like a node of the virtual enterprise network the multipolar model use different stochastic laws then the usual MTBF or MTR ones.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

The multipolar model describing the activity of the virtual enterprise network will be acting like a diffused manufacturing system where the work points are the four manufacturing systems models.

5. CONCLUSION

The main goal of our research was to propose an algorithm able to increase the productivity of virtual enterprises architecture by improving the discrete material flow management. As in our previous material flow simulation based algorithms in this new algorithm one can analyze the results of the material flow simulation, identify the flow concentrator for the diffused manufacturing architecture and propose an architecture modification as a solution for this problem. A second simulation to validate the optimized architecture and the obtained increase of productivity is necessary as well as a financial analysis must confirm the profitability of such a solution.

The main innovative character of our new multipolar synchronous simulation algorithm is given by the three kinds of synchronic simulation identified and used by us in building our model.

First of all at the level of each manufacturing system the CATIA process simulation for each work point is synchronic with the material flow simulation describing the entire system activity.

Secondly the simulation of the material flow multipolar model and the simulation of material flow for each manufacturing system model are synchronous.

Last but not least the integrated multipolar model is synchronizing the material flow and process simulation models for all the work points of the virtual enterprise architecture.

6. REFERENCES

Cotet, C.E., Dragoi, G.S. (2003). Material Flow Management in Validating Concentrate and Diffused FMS Architectures, In: International Journal of Simulation Modelling IJSIMM, no. 4, December 2003, pp.109-120, ISSN 1726-4529, Vienna.

Cotet C.E., Abaza B.F., Carutasu N.L. (2004)--Multipolar Distributed Simulation for Concentrate and Diffused FMS-Romanian Journal of Technical Sciences--Applied Mechanics, Tome 49, Editura Academiei Romane, 2004, p. 647-650. ISBN 973-27-1102-7; ISSN 0035-4074, Bucharest.

Lee, K. (1999). Principles of CAD/CAM/CAE Systems, Addison Wesley Longman, Inc., ISBN 0-201-38036-6, USA.

Sanchez, S. M. (2001). ABC's of output analysis, Proceedings of The 2001 Winter Simulation 2001, Peters, B.A., Smith, J.S., Medeiros D.J., CD-ROM, Presses Association for Computing Machinery (ACM), New York.

Tichkiewitch, S.; Radulescu, B. & Dragoi, G. (2006). Knowledge management for a cooperative design system, Advances in Design, ElMaraghy & Hoda A. Eds., pp. 97-110, Springer Verlag, ISBN 1-84628-004-4.
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