| 1. |
- Andersson, Lennart, et al.
(författare)
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Praktikfall i reglerteknik - Råspritbränneriet i Nöbbelöv
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- During spring 1998 the course Industrial Case Studies in Control was given at the Department of Automatic Control in Lund. The course consisted of a project at an industry with control applications. This report considers a project at the crude alcohol distillery in Nöbbelöv, where the base product for the liquor Absolut Vodka is produced. The distillery had problems with fluctuations in the concentration of ethanol in the crude alcohol. The purpose of the project was to analyze the cause of the fluctuations, and if possibly eliminate it. The fluctuations were cause by an output limiter on a controller, and were relatively easily eliminated. To examine if control performance could be further improved, a series of experiments was carried out on the plant. The result of the experiments were then used to derive a simple process model, and a suggestion for new controller parameters.
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| 2. |
- Johnsson, Charlotta
(författare)
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A Graphical Language for Batch Control
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis a graphical language for sequential control is presented and its application to batch control is examined and discussed. The name of the language is Grafchart. Its main feature is that it makes it possible to express complicated control problems in a compact and intuitive manner.Grafchart exists in two versions; a basic version and a high-level version. The basic version was available when the work presented in this thesis started. The basic version of Grafchart is mainly based on Grafcet, i.e., it has a clear and intuitive syntax. In addition to this it has support for parameterization and methods and message passing as well as extended facilities for exception handling. The high-level version of Grafchart takes the concepts of the basic version one step further. The concepts of object tokens and multi-dimensional charts are introduced. These features are inspired by high-level Petri nets and constructs from object-oriented programming languages.The main application area of Grafchart is batch control. In the thesis it is shown how Grafchart can be used for recipe structuring and recipe analysis. By using the features of Grafchart in various ways, recipes can be given different structures with different advantages and disadvantages. All structures comply with the international batch standard IEC 61512 (also refered to as ISA S88.01). To test and evaluate the different recipe structures, a real-time batch plant simulation platform was used. The batch recipe structures can be combined with resource allocation and a visualization of the allocation is thereby achieved. By transforming the recipes into an equivalent Petri net structure, formal analysis methods that exist for Petri nets can be used to look for possible deadlock situations.Several commercial batch control systems exist today. They all have a similar approach to recipe structuring, resource allocation and user presentation. The advantages of using Grafchart compared to some of these systems, regarding these features are presented in the thesis. A toolbox implementation of Grafchart exists. It is implemented in G2, an object-oriented programming environment. G2 is also an industrial environment, this makes the toolbox and the results of this thesis directly usable in industry.
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| 3. |
- Johnsson, Charlotta, et al.
(författare)
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Batch Recipe Structuring using High-Level Grafchart
- 1996
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Konferensbidrag (refereegranskat)abstract
- The paper presents how object-oriented sequential function charts can be used to implement a batch control recipe management system. Grafchart, a toolbox based on Grafcet, object-oriented programming ideas and High-level Petri nets, is presented. It is shown how the concepts of H-L Grafchart fit the models defined in the forthcoming ISA batch control standard SP88. A simulated batch process cell scenario is presented together with alternative ways of representing control recipes.
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| 4. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart and Batch Recipe Structures
- 1999
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Konferensbidrag (refereegranskat)abstract
- The paper presents how Grafchart can be used to implement batch recipe structures. Grafchart, a toolbox based on Grafcet/SFC, object-oriented programming constructs and ideas from high-level Petri nets, is presented in the paper. Grafchart exists in two versions, one basic version and one high-level version. By using the different features of Grafchart in various ways, recipes can be given different structures with different advantages and disadvantages. All structures comply with the batch standard ISA S88.01. In the paper four substantially different recipe structures are presented and their advantages and drawbacks are discussed. It is also shown how resource allocation can be handled.
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| 5. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart and Batch Recipe Structures
- 1998
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Konferensbidrag (refereegranskat)abstract
- The paper presents how Grafchart can be used to implement batch recipe structures. Grafchart, a toolbox based on Grafcet/SFC, object-oriented programming constructs and ideas from high-level Petri nets, is presented in the paper. Grafchart exists in two versions, one basic version and one high-level version. By using the different features of Grafchart in various ways, recipes can be given different structures with different advantages and disadvantages. All structures comply with the batch standard ISA S88.01. In the paper four substantially different recipe structures are presented and their advantages and drawbacks are discussed. It is also shown how resource allocation can be handled. This paper is an independent sequel to the paper "Object-oriented SFC and ISA S88.01 recipes" presented at WBF'96. This paper is an independent sequel to the paper "Object-oriented SFC and ISA S88.01 recipes" presented at WBF'96.
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| 6. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart and Grafcet: A Comparison Between two Graphical Languages Aimed for Sequential Control Applications
- 1999
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Ingår i: [Host publication title missing]. ; A, s. 19-24
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Konferensbidrag (refereegranskat)abstract
- This paper compares the language Grafcet with the language Grafchart. Both are graphical languages aimed for sequential control applications. Grafcet is aimed for specification of controller structures, i.e., for local level control applications. Grafchart is based on Grafcet, Petri nets and ideas from objectoriented programming and it can be used for any sequential control application, both applications on a local level and on a supervisory level. In addition to this, applications structured with Grafchart can be analyzed with respect to, e.g., deadlock situations, this is thanks to its foundation in Petri nets. In this paper, the similarities and the differences that exit between Grafcet and Grafchart are clarified and discussed.
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| 7. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart and its relations to Grafcet and Petri nets
- 1998
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Konferensbidrag (refereegranskat)abstract
- The paper presents Grafchart, a graphical programming language for sequential control applications. Grafcahrt has been influenced by Grafcet/SFC and Petri nets. In the paper the relations between Grafchart and Grafcet/SFC and between Grafcahrt and Petri nets are presented and discussed.
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| 8. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart Applications
- 1998
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Konferensbidrag (refereegranskat)abstract
- An overview of Grafchart, a graphical language for sequential control applications is given. Grafchart is based on Grafcet/SFC to which it adds concepts from high-level Petri nets, Statecharts and object-oriented programming. Applications of Grafchart in batch control, alarm filtering, decision support, and FMS are briefly presented.
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| 9. |
- Johnsson, Charlotta, et al.
(författare)
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Grafchart for Recipe-Based Batch Control
- 1998
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Ingår i: Computers and Chemical Engineering. ; 22:12, s. 1811-1828
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents how Grafchart, a toolbox based on Grafcet, object-oriented programming ideas and high-level Petri nets, can be used to implement a batch control recipe execution and recipe representation system,. A brief overview of Grafchart is given and it is shown how its concepts fit the models defined in the recent ISA batch control standard S88.01. A simulated batch process cell scenario is presented together with several alternative ways of representing batch recipes.
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| 10. |
- Johnsson, Charlotta, et al.
(författare)
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Object-Tokens in High-Level Grafchart
- 1996
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Konferensbidrag (refereegranskat)abstract
- The paper presents an high-level extension to Grafchart, a Grafcet-based toolbox for supervisory control applications. The extension allows tokens to be objects with attributes. Contrary to most high-level extensions to Petri Nets and Gracet it is not based on inscriptions.
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| 11. |
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| 12. |
- Johnsson, Charlotta, et al.
(författare)
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On Batch recipe Structures Using High-Level Grafchart
- 1998
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Konferensbidrag (refereegranskat)abstract
- Batch processes are very common and important in e.g. the chemical industries. The international standard ISA88.01 defines the terminology, the functionality and the models for batch control systems. The production specification of how to produce a batch, is called a recipe. This paper shows how high-Level Grafchart, a Grafcet and High-Level Petri net based programming language can be used to represent recipes and resource allocation. A number of different ways to represent recipes and resource allocation for multi-purpose batch plants are presented.
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| 13. |
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| 14. |
- Johnsson, Charlotta, et al.
(författare)
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Petri net Analysis of Batch Recipes Structured with Grafchart
- 1998
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Konferensbidrag (refereegranskat)abstract
- Grafchart is a graphical language aimed a sequential control applications. The language is implemented in a toolbox and it has been developed at the Department of Automatic Control in Lund, Sweden since 1991. The language is based on Grafcet and Petri nets and it can be used for sequential control applications on both the local and the supervisory level. The main application so far, has been batch recipe structuring. In this paper it is shown how Petri net analysis methods can be applied to batch recipes that are structured with Grafchart.
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| 15. |
- Johnsson, Charlotta
(författare)
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Recipe-Based Batch Control Using High-Level Grafchart
- 1997
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-Level Grafchart is a graphical programming language for control of sequential processes. Sequential control is important in all kinds of industries: discrete, continuous and batch. Sequential elements show up both on the local control level and on the supervisory control level. High-Level Grafchart combines the graphical syntax of Grafcet/SFC with high-level programming language constructs and ideas from High-Level Petri Nets. High-Level Grafchart can be used to control sequential processes both on the local level and on the supervisory control level. The main application area of High-Level Grafchart is control of batch processes, i.e., batch control. A batch process is a special class of sequential processes frequently occuring in chemical, pharmaceutical and food industries. Batch processes and batch control is currently the subject of large interest. A recent standard, called ISA S88.01, provides an important step towards a formal definition of batch systems. The specification of how to produce a batch is called a recipe. In the thesis it is shown how High-Level Grafchart can be used for recipe strucuring. By using the features of High-Level Grafchart in different ways, recipes can be represented in a number of alternative ways. They still, however, comply with the standard ISA S88.01. The different structures are presented and discussed. A simulation of a multi-purpose, network structured batch plant has served as a test platform. High-Level Grafchart, the recipe-execution system ad the batch plant are implemented in G2, an object-oriented programming environment.
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| 16. |
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| 17. |
- Simensen, Jo, et al.
(författare)
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A Multiple-View Batch Plant Information Model
- 1997
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Ingår i: Computers and Chemical Engineering. ; 21:SUPPL 1, s. 1209-1214
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a combined control and information model. Existing concepts from the information system area are modified to suit batch applications. The model has been applied to a simulated scenario consisting of a multi-purpose multi-path batch cell. The goal of the information model is to establish a framework for information systems that supports integrated batch plant operation.
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| 18. |
- Viswanathan, Shankar, et al.
(författare)
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Automating operating procedure synthesis for batch processes: Part I. Knowledge representation and planning framework
- 1998
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Ingår i: Computers and Chemical Engineering. ; 22:11, s. 1673-1685
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Tidskriftsartikel (refereegranskat)abstract
- Automating the synthesis of operating procedures for batch processes is very valuable as plant personnel often spend considerable amount of time and effort in preparing and verifying them for correctness and completeness. Towards this goal, a framework for automating operating procedure synthesis for batch processes is proposed in this paper. We propose an approach based on Grafcet, a discrete event modeling concept, to represent procedural knowledge combined with an object-oriented representation of the declarative knowledge. Grafcet is also used to model the information; called inferred knowledge, that is incrementally generated during operating procedure synthesis. The details of the basic components and the advanced features of Grafcet that make it a suitable technique for modeling the procedural and inferred knowledge are presented. A hierarchical planning strategy is proposed that uses the declarative and procedural knowledge to generate the inferred knowledge incrementally, which leads to the synthesis of the operating procedures. The implementa- tion of this framework and its application to an industrial case study are presented in Part II.
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| 19. |
- Viswanathan, Shankar, et al.
(författare)
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Automating Operating Procedure Synthesis for Batch Processes: Part II Implementation and Application
- 1998
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Ingår i: Computers and Chemical Engineering. ; 22:11, s. 1687-1698
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Tidskriftsartikel (refereegranskat)abstract
- A framework for operating procedure synthesis in batch processes was presented in part on of this paper. In this part, we present, iTOPS (intelligent tool for operating procedure synthesis), a knowledge based system for implementing the concepts outlined in the framework. iTOPS has been developed in Gensym's G2 expert system shell. The architecture of iTOPS, that consists of components that closely mirror the strategies of the synthesis framework, is described. The implementation and algorithmic details of each of these components in the iTOPS architecture are explained. Finally the application of iTOPS to on an industrial case study is presented.
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| 20. |
- Viswanathan, S., et al.
(författare)
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Knowledge Representation and Planning Strategies for Batch Plant Operating Procedure Synthesis
- 1996
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Konferensbidrag (refereegranskat)abstract
- Synthesis of operating procedures for batch plants involves systematic generation of step by step instructions which the operator can implement to manage the batch plant safely and optimally. This is a labor and knowledgeintensive task. It often takes weeks of effort by experts to prepare a clear and error free set of instructions even for a moderately complex plant. If this process is automated, it would be possible to develop operating procedures and control sequences more efficiently and accurately. This paper proposes a knowledge-based framework for this problem. The proposed framework has been implemented in Gensym’s object-oriented expert system environment called G2. The salient features of the framework have been tested on a real-life pharmaceutical case study and the results are found to compare favorably with the operating procedures that were developed by the experts.
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| 21. |
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| 22. |
- Årzén, Karl-Erik, et al.
(författare)
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Object-oriented SFC and ISA-S88.01 recipes
- 1996
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Ingår i: ISA Transactions. ; 35:3, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents how object-oriented sequential function charts can be used to implement a batch control recipe management system. Grafchart, a toolbox based on Grafcet, object-oriented programming ideas and High-level Petri nets, is presented. It is shown how the concepts of Grafchart fit the models defined in the ISA batch control standard ISA-S88.01. A simulated batch process cell scenario is presented together with alternative ways of representing control recipes.
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