Linköping Studies in Science and Technology

Dissertation No. 1337

Contributions to Modelling and Visualisation of Multibody Systems Simulations with Detailed Contact Analysis

by

Alexander Siemers

Department of Computer and Information Science Linköpings universitet

SE-581 83 Linköping, Sweden

Linköping 2010

To my childrenErik, Joel, and Lisa

Abstract

The steadily increasing performance of modern computer systems ishaving a large influence on simulation technologies. It enables increas-ingly detailed simulations of larger and more comprehensive simulationmodels. Increasingly large amounts of numerical data are produced bythese simulations.

This thesis presents several contributions in the field of mechanicalsystem simulation and visualisation. The work described in the thesis isof practical relevance and results have been tested and implemented intools that are used daily in the industry i.e., the BEAST (BEAring Sim-ulation Tool) tool box. BEAST is a multibody system (MBS) simulationsoftware with special focus on detailed contact calculations. Our work isprimarily focusing on these types of systems.

Research in the field of simulation modelling typically focuses on oneor several specific topics around the modelling and simulation work pro-cess. The work presented here is novel in the sense that it provides acomplete analysis and tool chain for the whole work process for simula-tion modelling and analysis of multibody systems with detailed contactmodels. The focus is on detecting and dealing with possible problemsand bottlenecks in the work process, with respect to multibody systemswith detailed contact models. The following primary research questionshave been formulated:

• How to utilise object-oriented techniques for modelling of multibodysystems with special reference to contact modelling?

• How to integrate visualisation with the modelling and simulationprocess of multibody systems with detailed contacts.

• How to reuse and combine existing simulation models to simulatelarge mechanical systems consisting of several sub-systems by meansof co-simulation modelling?

Unique in this work is the focus on detailed contact models. Mostmodelling approaches for multibody systems focus on modelling of bod-ies and boundary conditions of such bodies, e.g., springs, dampers, andpossibly simple contacts. Here an object oriented modelling approachfor multibody simulation and modelling is presented that, in comparisonto common approaches, puts emphasis on integrated contact modellingand visualisation. The visualisation techniques are commonly used toverify the system model visually and to analyse simulation results. Datavisualisation covers a broad spectrum within research and development.The focus is often on detailed solutions covering a fraction of the wholevisualisation process. The novel visualisation aspect of the work pre-sented here is that it presents techniques covering the entire visualisationprocess integrated with modelling and simulation. This includes a noveldata structure for efficient storage and visualisation of multidimensionaltransient surface related data from detailed contact calculations.

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Different mechanical system simulation models typically focus on dif-ferent parts (sub-systems) of a system. To fully understand a completemechanical system it is often necessary to investigate several or all partssimultaneously. One solution for a more complete system analysis is tocouple different simulation models into one coherent simulation. Part ofthis work is concerned with such co-simulation modelling. Co-simulationmodelling typically focuses on data handling, connection modelling, andnumerical stability. This work puts all emphasis on ease of use, i.e., mak-ing mechanical system co-simulation modelling applicable for a largergroup of people. A novel meta-model based approach for mechanicalsystem co-simulation modelling is presented. The meta-modelling pro-cess has been defined and tools and techniques been created to fullysupport the complete process. A component integrator and modellingenvironment are presented that support automated interface detection,interface alignment with automated three-dimensional coordinate trans-lations, and three dimensional visual co-simulation modelling. The inte-grated simulator is based on a general framework for mechanical systemco-simulations that guarantees numerical stability.

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Acknowledgements

The work presented in this thesis is a joint effort between the ProgrammingEnvironment Laboratory (PELAB) at Linkoping University and SKF GroupTechnology Development.

First would I like to thank my advisor Dag Fritzson and co-advisor PeterFritzson for initiating this work and making this thesis possible at all. Specialthanks to Dag Fritzson for co-authoring most of the papers in this thesis.

Thanks to all the people at PELAB for creating a nice working environ-ment at the university. Special thanks go to Iakov Nakhimovski for all BEASTcooperation, team-work in lectures and courses, and interesting discussions. Ialso would like to thank Vadim Engelson for all support and fruitful discussionsaround different topics of this thesis.

Many thanks to current and former BEAST team members at SKF: Lars-Erik Stacke, Mikael Holgerson, Hakan Bastedt, Alexei Jolkin, Jonas Stahl, KlasModin, Pietro Tesini, Stefan Nielsson, and Eric Svensson for all support andhelpful discussions and for making the office such a pleasant working place.

I am also grateful to all the administrative staff at IDA, especially LillemorWallgren and Bodil Mattson-Kihlstrom.

Finally, I would like to thank my wife Ulrika for all support and patience,my parents in Germany, and my friends in different countries around the worldfor all moral support and belief in my ability to finalize this work and write thisthesis.

Alexander SiemersGoteborg

October 2009

This work has been supported by SKF, the Swedish Foundation for StrategicResearch (SSF/ProViking), the Excellence Center in Computer Science andSystems Engineering in Linkoping (ECSEL), and the Knowledge Foundation(KK-stiftelsen/the Industry Graduate School).

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Contents

1 Overview 11.1 BEAST - Tool Box . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Main Contributions . . . . . . . . . . . . . . . . . . . . . . . . . 51.4 Visualisation of Dynamic Multibody Simulation Data . . . . . . 61.5 Meta-Modelling for Mechanical System Co-Simulation . . . . . . 91.6 Object-Oriented Modelling of Mechanical Systems . . . . . . . . 12

2 Overview of the Papers 13

Paper 1 17

3 Introduction 193.1 Multibody Simulation . . . . . . . . . . . . . . . . . . . . . . . 203.2 Overview of the Visualisation Process . . . . . . . . . . . . . . . 203.3 Requirements on the Visualisation System . . . . . . . . . . . . 22

4 Related Work 234.1 General Visualisation Systems . . . . . . . . . . . . . . . . . . . 234.2 Visualisation of Large Data Sets . . . . . . . . . . . . . . . . . . 234.3 Visualisation of CFD and FEA Data . . . . . . . . . . . . . . . 244.4 MSC.ADAMS - Multibody Simulation tool . . . . . . . . . . . . 24

5 Object Oriented Modelling of Multibody Systems 25

6 Surface Representations for Multibody Systems 266.1 Continuous Surface Representations . . . . . . . . . . . . . . . . 266.2 Discrete Surface Representations . . . . . . . . . . . . . . . . . 276.3 Surface Representations Used in this Work . . . . . . . . . . . . 27

7 Classification of Simulation Data 28

8 Data Storage and Access 298.1 Compression of Time-Varying Scalar and Vector Data . . . . . . 298.2 Storage of Scalar and Vector Data for Fast and Selective Access 30

9 Visualisation techniques for different types of data 31

10 The Visualisation System 3210.1 Body and Surface Rendering . . . . . . . . . . . . . . . . . . . . 3210.2 Visualising Multibody Dynamics . . . . . . . . . . . . . . . . . 3310.3 Vector Data (Forces and Motions) . . . . . . . . . . . . . . . . . 33

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10.4 Presenting Visualisation Results . . . . . . . . . . . . . . . . . . 34

10.5 Hardware Requirements for the Visualisation System . . . . . . 35

11 Conclusion 35

Paper 2 39

12 Introduction 41

12.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

12.2 Data Classification . . . . . . . . . . . . . . . . . . . . . . . . . 43

12.3 Organisation of this Paper . . . . . . . . . . . . . . . . . . . . . 45

13 The Visualisation Process 45

13.1 File Storage for Efficient Data Access . . . . . . . . . . . . . . . 46

13.2 Data Compression . . . . . . . . . . . . . . . . . . . . . . . . . 47

13.2.1 Common Compression Techniques . . . . . . . . . . . . . 47

13.2.2 Transient Data Compression in BEAST . . . . . . . . . . 47

13.3 Efficient Memory Management . . . . . . . . . . . . . . . . . . . 48

13.3.1 Performance Evaluation . . . . . . . . . . . . . . . . . . 51

13.3.2 Memory and File Size Evaluation . . . . . . . . . . . . . 51

13.4 Surface Representations . . . . . . . . . . . . . . . . . . . . . . 52

13.4.1 Discrete Surface Representations . . . . . . . . . . . . . 52

13.4.2 BEAST Surface Representations . . . . . . . . . . . . . . 53

13.5 Surface Data Mapping . . . . . . . . . . . . . . . . . . . . . . . 55

13.5.1 Common Methods . . . . . . . . . . . . . . . . . . . . . 56

13.5.2 Surface Data Visualisation . . . . . . . . . . . . . . . . . 56

13.6 Rendering Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

14 Scalability of the Visualisation System 58

15 User Interaction 59

16 Conclusion 60

Paper 3 65

17 Introduction 67

17.1 Sub-Surface Data . . . . . . . . . . . . . . . . . . . . . . . . . . 68

17.2 Parallel Simulation . . . . . . . . . . . . . . . . . . . . . . . . . 68

17.3 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

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18 Related Work 6918.1 Visualisation of Large Data Sets . . . . . . . . . . . . . . . . . . 6918.2 Volume Visualisation . . . . . . . . . . . . . . . . . . . . . . . . 70

19 A Data Structure for Sub-Surface Data 70

20 Visualisation of Sub-Surfaces 71

21 Surface Data Packaging for Parallel Simulation 7221.1 Packing Technique . . . . . . . . . . . . . . . . . . . . . . . . . 72

22 Conclusion 73

Paper 4 77

23 Motivation 79

24 Transmission Line Modelling 80

25 Simulation Framework 81

26 Modelica as Meta-Model Language 8226.1 Meta-Model Class Library . . . . . . . . . . . . . . . . . . . . . 8226.2 Component Modelling . . . . . . . . . . . . . . . . . . . . . . . 8426.3 Meta Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . 8526.4 Meta-Model Translation . . . . . . . . . . . . . . . . . . . . . . 8626.5 Meta-Model Example . . . . . . . . . . . . . . . . . . . . . . . . 86

27 Conclusion 90

Paper 5 93

28 Motivation 95

29 Meta-Modelling 9629.1 Meta Model Representations . . . . . . . . . . . . . . . . . . . . 9729.2 Meta Modelling Language . . . . . . . . . . . . . . . . . . . . . 99

30 Meta-Modelling Environment 10130.1 External Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 10230.2 Interface Alignment . . . . . . . . . . . . . . . . . . . . . . . . . 103

31 Verification 103

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32 Conclusion 104

Paper 6 107

33 Introduction 109

34 Meta-Models 111

34.1 Meta-Model Language . . . . . . . . . . . . . . . . . . . . . . . 113

34.2 Meta-Model Editor . . . . . . . . . . . . . . . . . . . . . . . . . 116

35 Co-Simulation Framework 116

35.1 Requirements on External Model Simulators . . . . . . . . . . . 117

36 Transmission Line Based Co-simulations 118

36.1 TLM Background Theory . . . . . . . . . . . . . . . . . . . . . 119

36.2 Benefits of TLM Element . . . . . . . . . . . . . . . . . . . . . . 121

37 Meta-Model Simulation 122

38 System Verification 124

39 Performance Evaluation 126

40 Conclusion 128

Paper 7 131

41 Introduction 133

42 Grinding Spindle Application 134

43 Meta-Model based Co-Simulation 135

43.1 Meta-Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

44 Co-Simulation Framework 136

44.1 Transmission Line Modelling . . . . . . . . . . . . . . . . . . . . 137

45 Grinding Spindle Model 139

45.1 External Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

45.2 Time and Loading Conditions . . . . . . . . . . . . . . . . . . . 141

46 Results 144

46.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

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Paper 8 149

47 Introduction 15147.1 Modelling and simulation environments . . . . . . . . . . . . . . 15247.2 Structuring of this paper . . . . . . . . . . . . . . . . . . . . . . 152

48 Object-Oriented concepts applied to multibody-systems 15448.1 Associations in object-oriented models . . . . . . . . . . . . . . 155

49 Tools for modelling mechanical system simulations 15549.1 Modelica and BEAST/BML . . . . . . . . . . . . . . . . . . . . 156

50 Contact modelling and encapsulation for 3D mechanics 157

51 Model libraries and model composition 16451.1 Model composition . . . . . . . . . . . . . . . . . . . . . . . . . 165

52 Conclusion 166

Glossary 172

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1 Overview

Simulations of system models offer a cost effective and safe way for the investi-gation of mechanical systems. Accordingly, this approach has gained increasingattention in the industry. Instead of using an expensive and complex test-rig,a simulation program (a virtual test-rig) is used, which often saves time andmoney. Simulation models are generally more flexible than hardware proto-types, i.e., they are easy to adjust to new system properties, and output can begathered on demand. Some of the advantages of simulations are:

• Design modifications are simple. Several designs can be tested withouthigh manufacturing costs.

• Development time can be reduced significantly.

• Some parts within mechanical systems are difficult or impossible to mea-sure. Simulations on the other hand allow investigation of any part of thesystem that can be physically modelled.

• Low risk.

The steadily increasing performance of modern computer systems has a sig-nificant influence on simulation technologies. Increased computer performanceenables more detailed simulations. A growing amount of numerical data isproduced by these simulations. This is especially true for transient (dynamic)simulations, for instance, dynamic multibody simulations.

All parts of the work described in this thesis have practical relevance andhave been tested and implemented in tools that are used daily in the industry,i.e., the BEAST “BEAring Simulation Tool” tool box.

1.1 BEAST - Tool Box

The BEAST project was initiated by SKF with the intention of creating a threedimensional dynamic rolling bearing simulation tool for simulation of bearingsunder predefined loading conditions. A decade later BEAST is a fully functionaldynamic simulation program for different types of multibody systems. BEASTis a “Tool-Box” that consists of several tools for conducting simulations andanalysing simulation results, see Figure 1. The tools are:

Beast is the tool that conducts the numerical simulation. Beast takes a param-eter file as input that describes the model geometry, boundary conditions,and other simulation and model specific parameters. The outcome of thenumerical simulation is large sets (up to several gigabyte) of dynamicdata.

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Input

Output

RunBeast

ViewBeast

Beauty

Beast

Out2In

Figure 1: The BEAST Tool Box.

Beauty is an advanced 3D visualisation and animation tool. It is used for pre-and post-processing of BEAST simulations. All input parameters andall model geometry is defined and verified during pre-processing. Beautysupports different methods for post-processing of simulation data, some ofwhich are: animation of time dependent data, motion magnification, andvisualisation of contact related data such as contact forces and pressuredistributions. Much of the work presented here has been accomplishedwithin the scope of this tool.

Out2In is used to convert simulation output files to input files. This is usefulfor restarting simulation from a certain time step, typically to test differentinput parameters within a certain time frame of the simulation.

RunBeast is used to start and monitor simulations on remote machines. Beastsupports parallel simulation, i.e., simulations are typically submitted toa computer cluster where a single simulation utilises several CPU (Cen-tral Processing Unit) cores simultaneously to shorten simulation time.RunBeast provides the interface to the computer cluster from the usersmachine, where users typically run the BEAST software on a workstationor laptop.

ViewBeast is an advanced tool for two dimensional plotting of simulationdata. Scalars and vectors can be investigated. ViewBeast supports time-frame selection, labelling, storage of plot descriptions, and much more.A calculator is provided to create user defined mathematical expressionsbased on Beast output variables.

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1.2 Objectives

Research in the field of simulation modelling is typically focusing on one orseveral specific topics around the modelling and simulation work process. Thework presented here is novel in the sense that it provides a complete analysis andtool chain for the whole work process for simulation modelling and analysis ofmultibody systems with detailed contact models. The method chosen to achievethis is to analyse the complete work-process for modelling and simulation ofmultibody systems with detailed contact models and focus on possible problemsand bottlenecks. A typical work process for modelling and simulation can bedivided into three steps:

1. Pre-processing (modelling). For mechanical systems with detailedcontacts this preferably involves a graphical user interface with three di-mensional detailed surface modelling and visualisation capabilities. Thisis because calculation of detailed surface contacts requires detailed surfacemodels.

2. Simulation. The actual calculation of detailed contact models oftenrequires long simulation time and might produce a lot of simulation datathat needs to be analysed.

3. Post-processing (data analysis). Data selection and visualisationtechniques are typically used when analysing large amounts of data pro-duced by a simulation program. For mechanical system simulation agraphical user interface with three dimensional visualisation capabilitiesis desirable.

Unique in this work is the focus on detailed contact models. It influences thework process in all its phases and puts special requirements on the multibodysystem model, data handling, and the graphical user interface, including visual-isation techniques. Furthermore, the work presented here addresses mechanicalsystem co-simulation modelling. The fundamental questions addressed in thiswork are:

• How to integrate visualisation with the modelling and simulation processof multibody systems with detailed contacts?Dynamic, or transient, simulations often produce large amounts of data.This is especially true for computation intensive simulations where a sin-gle simulation execution can take up to several days. Re-running suchsimulations is time consuming and thus costly. In such situations it is ad-vantageous to store all information that might be of interest (and that canbe produced) right from the beginning, i.e., to avoid additional simulationexecutions. Visualisation and data-selection techniques are then neededto analyse the large amount of data. Large data sets put special require-ments on a visualisation system. Moreover, detailed contact analysis is

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used to investigate surface related phenomena such as, contact pressuredistribution, rolling contact fatigue, and wear. This puts high demandson the contact geometry, i.e., detailed surface and contact descriptionsare needed. Part of this thesis is concerned with visualisation of largetransient data sets and detailed contact phenomena.

• How to reuse and combine existing simulation models to simulate large me-chanical systems consisting of several sub-systems by means of co-simulationmodelling?Different simulation models typically focus on different parts (sub-systems)of a mechanical system, e.g., the gear-box of a car, the drive-line, or evena single bearing inside the gear-box. To fully understand the completemechanical system it is necessary to investigate several or all parts simul-taneously. This is especially true for transient (dynamic) simulations withseveral interconnected parts. One solution for a more complete systemanalysis is to couple different simulation models to form one coherent sim-ulation. This is sometimes called a coupled simulation or co-simulation.Co-simulations often interconnect two specific simulators where a uniqueinterface between these tools is defined. However, a more general solutionis needed to make co-simulation and co-simulation modelling easy to applyto a larger range of tools. Part of this thesis describes a general approachfor modelling and management of mechanical system co-simulations. Fur-thermore focus co-simulation modelling approaches typically on data han-dling, connection modelling, and numerical stability. Here all emphasis isput on ease of use, i.e., making mechanical system co-simulation modellingapplicable for a larger group of people.

• How to utilise object-oriented techniques for modelling of multibody sys-tems with special reference to contact modelling?At the lowest and most fundamental level of mechanical system mod-elling there are mathematical formulations. More specifically this meansthat the different physical properties of a mechanical system are describedwith mathematics, i.e., equations, mathematical functions, formulae, etc.However, when dealing with modelling of complete systems a pure math-ematical description of the system might be hard to formulate. Higherabstraction is therefore needed for large systems especially with respect toreusability, maintainability, and adjustability, i.e., testing different mathe-matical models, algorithms, and mechanical parts within the same system.Part of this thesis deals with this class of problems through techniques forobject-oriented modelling of mechanical systems. Special focus is put onencapsulation in conjunction with contact modelling.

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1.3 Main Contributions

The main contributions of this work can be summarised as follows:

• Integration of the complete visualisation process for multibody simulationdata including techniques and tools for: surface and data visualisation,data storage, image rendering, and user interfaces. Visualisation researchtypically focuses on one detailed visualisation issue, e.g., a new compres-sion algorithm for 3D meshes. The novel visualisation aspect of the workpresented here is that it presents techniques covering the entire visualisa-tion process integrated with modelling and simulation.

• A novel sparse data structure that supports efficient lossless compressedstorage, access, and network transport of multi dimensional transient datasets that are produced by detailed surface-to-surface contact calculations.One important aspect in visualisation of contact related data is to pro-cess two dimensional data that often has sparse topology. Existing datastructures for sparse 2D data sets, e.g., sparse matrices, are typically opti-mised for efficient data storage but often lack features that are needed fortime continuous simulation and visualisation, e.g., fast random data ac-cess and fast memory reallocation. This is addressed by the data structurepresented here.

• A generic and uniform approach to connect various simulation tools bymeans of a meta-model. Distributed co-simulation implementations of-ten lack flexibility, i.e., they suffer from specialised interfaces betweenthe simulation tools and system dependency, i.e., network parameters,tool dependent parameters, and machine names are stored in the model.The meta-models presented here provide a generic way to connect vari-ous simulation tools. Well defined interfaces are used that allow a uni-form connection of the tools. All operating system, network, or otherco-simulation-platform dependent parameters are strictly separated fromthe meta-model. Furthermore, the meta-model is based on a languagerepresentation with strict notation and grammar. Graphical language el-ements are possible for visual representations of the meta-model.

• A novel meta-model based approach for mechanical system co-simulationmodelling is presented. A meta-modelling process for co-simulation mod-elling has been defined. The different phases of a meta-modelling processhave been identified. This work puts all emphasis on ease of use, i.e.,identifies obstacles in the different phases that might hinder the usage ofco-simulation and co-simulation modelling and presents solutions. Tech-niques and tools for co-simulation meta-modelling have been designed tomake meta-modelling for mechanical system co-simulation applicable, in-

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cluding tools for simulation model encapsulation, model verification, andvisual (3D) meta-modelling.

• Comparison of different object-oriented modelling approaches applied tomultibody system simulations with detailed contact descriptions. Differenttools with support for multibody simulation exist, some of which useobject oriented models for the multibody system. Two such approaches tomodelling have been compared in this work with special focus on surfacecontact modelling and its relation to the object oriented model.

• Implementation of the presented techniques in an industrial multibodysimulation system called BEAST.

1.4 Visualisation of Dynamic Multibody Simulation Data

Visualisation of simulation results is present everywhere in areas of modellingand simulation. There are general simulation tools, such as multi physics sim-ulation tools, i.e., Simulink [9], Ptolemy-II [2], and Modelica [4] based envi-ronments [8] and Dymola [3] that provide block diagrams for the modellingphase and sometimes simple 3D visualisation and animation for the analysis ofmechanical system simulations. Concerning multibody system modelling thesetools suffer from a lack of 3D pre-processing and detailed visual post-processing.Multibody system simulation tools, such as, MSC-ADAMS [10], typically sup-port 3D visualisation both, for pre- and post-processing. These tools have lim-ited capabilities for very detailed analysis of contact related phenomena, e.g.,slip velocity, pressure distribution, fatigue, structural deformations (local andglobal), and material removal. It requires very detailed surface models and visu-alisation. More general visualisation tools, such as, ParaView [7], TechPlot [15],or OpenDX [5], provide many features for multi domain data exploration butcannot handle large transient data sets that contain thousands of variables.Typically, they require to extract and transform certain data sets and time se-ries to be able to analyse the data partially. A more integrated and completeapproach is desirable from a usability point of view.

In the work presented here visualisation is fully integrated with modellingand simulation:

• Models are created using a tool which provides three dimensional repre-sentations of the entire model with detailed contact surface modelling.

• Visualisation is entirely based on the simulation model. Any change inthe model structure directly affects the visual representation of the model.

• Large amounts of dynamic data can be analysed by means of three di-mensional animation, including: selection of data set and time interval,visualisation of system dynamics with geometry changes, etc.

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Part of this thesis deals with the visualisation of data produced by BEAST.Specialised visualisation techniques and tools are advantageous when analysingBEAST data. The core application utilised for the research presented here isBeauty, the 3D visualisation tool of BEAST, see Figure 2. Visualisation ofmechanical systems and related data is not a new problem. Furthermore, thework presented here does not focus on one specific aspect of that field. Insteadthis work is concerned with how several aspects are integrated in one specificapplication area, i.e., multibody system dynamics with detailed contact analy-sis. More specifically concerning visualisation of data produced by simulationsof bearings and bearing related applications. As stated in [6] there is littleprevious work concerned with the understanding of the integrated visualisationprocess itself. In the work presented here the entire visualisation process forthese specific data sets has been analysed and transformed into a complete andworking integrated visualisation system, see Paper 1 and Paper 2 for details.Paper 1 puts more emphasis on the visualisation process with background in-formation while Paper 2 presents the techniques designed and implemented inBeauty in more detail.

Figure 2: Beauty, the 3D visualisation tool of the BEAST tool-box. It offersa model tree view and a full 3D view on the system. Part of a universal-jointmodel with some contact related data is shown.

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Table 1: Performance and programming effort on different application and APIlevels.

Low programming effort Other simulation MSC.ADAMS, ABAQUS,Less performance tools ...

General visualisation Amira, OpenDX,tools ...

Visualisation 3D Master Suite, VTK,libraries ...

High level 3D Open Inventor, Openlibraries Scene Graph, ...

High programming effort low level 3D OpenGL, PEX,High performance libraries Direct3D, ...

Generally, the choice of the visualisation system or architecture is a balancebetween programming effort and performance, see Table 1. On the high endthere are existing simulation tools that solve certain problems and bring theirown visualisation tools. At the low end there are low level 3D libraries thatoffer the best performance but require some programming effort. Differentsolutions have been tested for the data used here. Other simulation tools donot satisfactorily solve the problems addressed by BEAST, at least not regardingintegration and desired detail. We found that general visualisation tools andhigher level visualisation libraries have performance issues with the amount ofdata and number of variables used here. OpenGL [17] has been chosen as thegraphics API for Beauty because it offers good performance, the highest levelof flexibility, and portability.

So, what is a multibody system and what are the specific characteristicsof the data created by BEAST? Multibody systems are used to model and in-vestigate mechanical systems in which several bodies interact with each other.Examples of multibody systems are: rolling bearings, gearboxes, and cars. Sim-ulations are conducted to increase the understanding of the dynamic behaviourand interaction between the bodies. Detailed contact analysis is used to inves-tigate surface related phenomena such as, contact pressure distribution, rollingcontact fatigue, and wear. This puts high demands on the contact geometry,i.e., detailed surface and contact descriptions are needed. For instance, con-tacts between two bodies often result in local surface deformation, e.g., wear,material removal and structural deformation of the body, such as, flexibility orelasticity. To achieve this, new adaptive visualisation techniques for surfaces arepresented in this work, including: dynamic surface meshes with level of detailmethods, see Sections 13.4.2 and Section 15, and user adjustable magnification

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mechanisms, see Section 15. Furthermore, contact calculations are computa-tion intensive and when applied to transient problems result in large amountsof multidimensional data, both in the time domain, i.e., many thousands oftime steps, and in the data domain, e.g., pressure distribution over the surfaceor higher order tensors for material stresses. Techniques for handling this typeof data include: lossless data compression, see Section 13.2, and a new adaptivedata structure for two dimensional surface related data sets, see Section 13.3and Section 13.5.2. Contact stresses between two surfaces affect the materialunderneath the surface. These stresses need to be stored during simulation andvisualised during animation. This work classifies these stresses as sub-surfaces,thus a thin layer volume underneath the surface of the body. Techniques, in-cluding a new data structure, for storage and visualisation of sub-surface dataare described in Paper 3.

It should be noted that BEAST and Beauty are mainly used for bearingapplications with focus on detailed contact modelling. However the techniquespresented in this thesis can also be applied to other application areas wherecontact plays an important role, e.g., gearwheel contacts, ball screws, rollerscrews, and ring grinding applications.

1.5 Meta-Modelling for Mechanical System Co-Simulation

Part of this work is concerned with co-simulation modelling based on a generalframework for meta-model based co-simulations, see Paper 4, Paper 5, and [11]for details about the framework. Existing co-simulation environments typi-cally define communication interfaces by means of network addresses and datatypes and thus introduce system dependent co-simulation models that oftenrequire manual startup of all the simulation tools involved. Furthermore, inthe best case, these environments support two dimensional block diagrams forco-simulation modelling to represent the interconnections between the differentco-simulation components. The work presented here introduces meta-modellingfor mechanical system co-simulation where the meta-model defines the physi-cal interconnections of various external models. An external model is a modeldefined in some specific modelling language supported by modelling and simu-lation tools that can perform a simulation of it. Each external model has oneor more, but can have several external interfaces for connection to other exter-nal models. By interconnecting several external models, the (extended) overallstructure of the system model is created.

Co-simulation implementations often lack portability and flexibility, i.e.,they suffer from specialised interfaces between the simulation tools and gen-erate system dependent models. The meta-modelling approach presented hereprovides a generic way of connecting various simulation tools. Well definedinterfaces are used that allow a uniform connection of the tools. Common co-simulation environments such as, for instance, Cosimate [16], often exchange

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data using a shared memory model, i.e., two connected simulation tools writedata into a certain memory address that is provided and managed by the co-simulation environment. These connections are defined in terms of memory ad-dresses and data types and do not guarantee numerically stable co-simulation.The external interfaces defined in the work presented here introduce a higherlevel of abstraction by defining unified interfaces in terms of mechanical ve-locity and reaction forces, and provide a numerically stable method by meansof TLM, see also Section 36. One issue of distributed co-simulations is porta-bility, i.e., co-simulation models often contain system dependent parameterssuch as, for instance, network ports and machine names that are needed to runthe different simulation tools and models involved in a co-simulation. In themeta-model approach presented in this work all operating system, network, orother co-simulation-platform dependent parameters are strictly separated fromthe meta-model. Instead, the system requires one initial set-up to be able torun meta-model based co-simulations, see also Section 37. This implies thatthe meta-model based co-simulation could theoretically run on other architec-tures than the presented co-simulation environment as well, e.g., the High-LevelArchitecture [1] (HLA). Furthermore, the meta-model language representation,with strict notation and grammar, allows sharing of meta-model informationbetween different tools and people, see also Section 29.2. Different tools can beadapted to read and process the complete meta-model. Graphical language ele-ments allow for three-dimensional visual representations of the external models.

The early work presented in Paper 4 utilises the Modelica [4] language todescribe the meta-model in an easy to understand, object oriented way. AModelicaXML [12] based translator is used to convert Modelica code to anXML document which is accepted as input by the co-simulation engine. Laterthis work has been further extended to improve meta-model simulation pre-and post-processing, i.e., fully three dimensional model editor and meta-modelanimations, see Paper 4 for details about the modelling environment and thedefined meta-modelling process. Furthermore, the XML based language haslater been redesigned to remove XML-tags for improved readability, addinghierarchical constructs to allow for hierarchical meta-models, and integratinggeometrical elements for improved meta-model visualisation.

Model abstraction, where each external model is represented uniformly andindependently form a simulation-tool, is an important feature of the meta-model. Every external-model can be seen as a black-box, with unified interfaces,representing a particular simulation tool. Meta-models can thus be designed,shared, and discussed without the need to understand the simulation tools thatare involved in the co-simulation.

Meta-models also simplify centralised co-simulation control, where a singlesimulation manager can execute and control the co-simulation based on themeta-model. Correct simulation tool start-up and communication between thetools can be managed and monitored in a better way. This allows a controlled

10

reaction on execution and communication problems and to log all communicateddata. Paper 6 discusses the meta-model based co-simulation environment indetail.

All the work described here is of practical relevance and has been realisedwithin the scope of the BEAST tool box. An example of a meta-model basedco-simulation is presented in Paper 7. A rotor-dynamics application, a grindingspindle arrangement, is presented that contains several non-linear components,e.g., two ball bearings supporting the spindle shaft and a control system deter-mining the rotation of the shaft. A total of four simulation models have beenconnected by means of a meta-model that contains an MSC.ADAMS [10] spin-dle model, two BEAST [14] ball bearings fixing the shaft in the housing, and aSimulink [9] driver that controls the rotation of the shaft.

To advance the applicability of co-simulation meta-modelling the differentphases of the meta-modelling process have been identified. Unique in this workis the focus on the user perspective on the meta-model process for mechanicalsystem co-simulations, i.e., ease of use. Here a classification and partitioningof the process into three stages has been defined: external model design, modelintegration, and meta-model design, see Section 29 and Section 34 for details.To fully support the complete process in all its stages an external model inte-grator and meta-model editor have been created that support, for instance, au-tomated external interface detection, interface alignment with automated threedimensional coordinate translations, and three dimensional visual co-simulationmodelling, see Section 30.

In conclusion, the following methods and tools are utilised to support easeof use in co-simulation modelling:

• Based on a framework that supports numerically stable co-simulation,interface plugin that can be adjusted to many simulation tools, automaticunit adjustment, and more, see Paper 4, Paper 5, and [11] for details.

• Meta-model based co-simulation that provides:

System independent models, Meta-model designer does not need toknow about computer system and network details.

Model abstraction, where each external model is represented uni-formly and independently of a simulation tool.

A generic and uniform way to connect various simulation tools. Alltools implement a single unified external interface.

• Meta-model editor with three dimensional visual representations of theexternal models, all interfaces, connections, and model hierarchy. Exter-nal models are visualised using standard virtual reality markup language(VRML) files.

11

• An external model integrator for easy simulation model encapsulation andintegration. Model files, VRML files, and start method need to be entered.All files are automatically copied into the meta-model archive.

• Automated external interface detection. External interfaces are definedin the specific simulation tools of the external model, e.g., BEAST, MSC-ADAMS, or Modelica. For mechanical system co-simulations correct po-sition and orientation of the interface is required. Also names of interfacesare needed for correct connection modelling. Often the meta-model de-signer does not have knowledge of all the simulation tools involved andmight not have appropriate information about all the interfaces. There-fore the external model integrator can request this information directlyfrom the simulation model through the co-simulation framework.

• External Interface alignment. A correct meta-model requires that any twoconnected TLM interface points have the same start position and orienta-tion relative to the meta-models global inertial coordinate system. In somecases the different modelling tools use different local inertial coordinatesystems. To avoid redesign of the external model in its specific modellingenvironment the meta-model editor allows for the alignment of any twoselected interface points automatically. The calculated transformationsare stored in the meta-model.

• Execution in separate directories. All external models are automaticallyexecuted in separate directories during the co-simulation. This to avoidnaming conflicts, i.e., the same external model can be used more thanonce in a meta-model.

1.6 Object-Oriented Modelling of Mechanical Systems

A mechanical system simulation can be based on several mathematical modelseach of which represents a physical phenomenon. Expressing the behaviour ofa large mechanical system with basic mathematical formulations, i.e., just sys-tems of equations without additional structuring information, is typically hardto achieve. A higher level of abstraction is therefore needed for modelling andsimulation of large mechanical systems. Especially with respect to reusability,maintainability, and adjustability, i.e., testing different mathematical models,algorithms, or system set-ups. One approach to model abstraction is to di-vide the model into several interacting components that can be handled oneby one. A common method for representing mechanical systems as interdepen-dent components is called multibody system modelling. Another, more general,method is called object-oriented modelling [13]. One key concept to handlecomplexity in object-oriented design is encapsulation. Interfaces are defined forthe external interaction of a component, whereas internal details are hidden.

12

Complex systems such as, for instance, cars or airplanes consist of many com-ponents, which in turn consist of many components — hierarchically throughmany levels. Therefore composition is built into modelling languages such asModelica. External interfaces must be defined for external interaction, whereasinternal components cannot be accessed if they are not available through theseinterfaces.

Paper 8 introduces basic object-oriented concepts, with applications to multi-body systems with detailed contact models. Modelica-based tools and theBEAST tool and their application to multi-body system modelling are dis-cussed. Section 50 discusses and compares different concepts of encapsulationand mechanical contacts in the context of multi-body system modelling, withspecial reference to the Modelica and BEAST approaches. It is argued thatinterface propagations as used in Modelica provides clean interface definitionswith data encapsulation and information hiding. This approach works wellfor modelling of many systems but is not sufficient for convenient modellingof multibody contacts where globally accessible interfaces are needed in thecontext of accessible mechanical surfaces and components. It is briefly demon-strated that simple modifications to the Modelica language would allow for moreconvenient connection modelling through multiple hierarchical levels.

2 Overview of the Papers

This thesis consists of several papers, three that present multibody data visual-isation, four addressing meta-modelling for mechanical co-simulation, and onethat is concerned with object oriented modelling of mechanical systems. Herefollows a short overview of the papers:

1. Visualisation of Dynamic Multibody Simulation Data.This paper describes what is needed to create a complete multibody visu-alisation system. The complete visualisation process, from data storage toimage rendering is discussed. Special attention is placed on visualisationof multibody dynamics and contact related vector data, e.g., forces andmoments.

2. Visualisation and Data Representation for Large-Scale Multi-body Simulations with detailed contact analysis.Beauty, an integrated visualisation and simulation tool for multibody-systems with detailed contact analysis applied to transient dynamics ispresented in this paper. The simulation program produces a large amountof data and many time steps which requires data compression. A losslesscompression algorithm specially designed for time-varying data is used.Selective data access is required for visualisation of transient data sets.

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A block based streaming technique with fast selective data access is pre-sented that allows for realistic animations of mechanical system dynamics.Furthermore, different representations of surfaces and surface related dataare presented that are used throughout the visualisation process.

3. Sub-Surface Visualisation and Parallel Simulation.This paper focuses on the visualisation of contact stresses. Contact stressesbetween two surfaces penetrate the material underneath the surface. Thesestresses need to be stored during simulation and visualised during anima-tion. They are classified as sub-surfaces, thus a thin layer volume under-neath the surface. A sub-surface data structure is presented that inheritsproperties of the earlier defined surface data structure and adds addi-tional capabilities for visualisation of volumes. Another topic is parallelsimulation that puts special demands on the surface data and sub-surfacedata structures. Data has to be packed and distributed to the differentsimulation nodes efficiently, in order to achieve good speed-up. Specialattributes of the data are used to minimise the data to be packed. Toachieve fast data transmission, all data is packed into one buffer.

4. Meta-modelling of Mechanical Systems with Transmission LineJoints in Modelica.A framework for meta-modelling with Transmission Line (TLM) joints ispresented. The framework is intended to support transient simulations ofmechanical systems using co-simulation of different tools. The expressivepower of the Modelica language is used to describe the meta-model in aneasy to understand, object oriented way. The main focus is on modellingof co-simulation Meta-Models taking advantage of Modelicas graphicaland object-oriented modelling capabilities.

5. A Meta-Modelling Environment for Mechanical System Co-Simulations.This paper presents a general approach for modelling of mechanical systemco-simulations. The concept of meta-modelling is applied to mechanicalco-simulations. Several tool-specific simulation models can be integratedand connected by means of a meta-model, which defines the physical in-terconnections of these models. A fully functional modelling environ-ment is described that features a graphical user interface for co-simulationmodelling with support for three dimensional visual representation of theco-simulation meta-model including all its components. The modellingenvironment supports easy encapsulation and integration of simulationtool-specific models.

6. General Meta-Model Based Co-Simulations Applied to Mechan-ical Systems.The meta-model co-simulation environment that supports integration of

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many different simulation tool specific models into a co-simulation is de-scribed in this paper. The presented approach for mechanical systemco-simulations is based upon a general framework for co-simulation andmeta-modelling. Several tool specific simulation models can be inte-grated and connected by means of a meta-model. A platform indepen-dent, centralised, meta-model simulator is presented that executes andmonitors the co-simulation. All simulation tools that participate in theco-simulation implement a single, well defined, external interface that isbased on a numerically stable method for force/moment interaction.

7. Non-Linear Rotor-Dynamics Modelling using Co-Simulation.This paper describes a rotor-dynamics application, a grinding spindle ar-rangement, that has successfully been modelled and simulated using thegeneral framework for co-simulation and meta-modelling. Four simulationmodels have been connected by means of a meta-model, that contains anMSC.ADAMS spindle model, two BEAST ball bearings fixing the shaft inthe housing, and a Simulink driver that controls the rotation of the shaft.Rotor-dynamics effects, such as, grinding-wheel vibrations and stiffnessare presented to verify the results of the simulation.

8. Object-Oriented Modelling for Mechanical-System Simulations— Comparison of Modelica and BEAST models.The application of object oriented techniques to mechanical system mod-elling is discussed in this paper. The focus is on modelling of multibodysystems. BEAST and Modelica — a language for multi-physics simula-tions, are used as reference, both of which have object oriented modellingsupport, are used as reference. The main differences between these ap-proaches are pointed out and discussed.

References

[1] IEEE Standard 1516-2000. High level architecture (hla) - framework andrules. IEEE Standard for Modeling and Simulation, May 2000.

[2] J. Eker, J. W. Janneck, E. A. Lee, J. Liu, X. Liu, J. Ludvig, S. Neuendorf-fer, S. Sachs, and Xiong Y. Taming heterogeneity—the ptolemy approach.In Proceedings of the IEEE, volume 91. IEEE, January 2003.

[3] H. Elmqvist. Dymola user’s manual - version 5.0a, 2002.http://www.dynasim.com.

[4] P. Fritzson. Object-Oriented Modeling an Simulation with Modelica 2.1.Wiley-Interscience, 2004.

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[5] Opendx - software package for the visualization of scientific, engineeringand analytical data, 2010. http://www.opendx.org.

[6] T.J Jankun-Kelly, Ma Kwan-Liu, and M. Gertz. A model for the visual-ization exploration process. Visualization, 2002. VIS 2002. IEEE, pages323–330, Nov. 2002.

[7] Paraview - an open-source, multi-platform data analysis and visualizationapplication, 2010. http://www.paraview.org.

[8] Mathmodelica - model based design of multi-engineering systems, 2010.http://www.mathcore.com/products/mathmodelica.

[9] Simulink - simulation and model-based design, 2010.http://www.mathworks.com/products/simulink/.

[10] Msc software corporation website, 2008. http://www.mscsoftware.com.

[11] I. Nakhimovski. Contributions to the Modeling and Simulation of Me-chanical Systems with Detailed Contact Analysis. PhD thesis, Linkopingsuniversitet, Sweden, 2006. Dissertation No. 1009.

[12] A. Pop and P. Fritzson. Modelicaxml:a modelica xml representation withapplications. In Modelica 2003 Conference, 2003.

[13] J. Rumbaugh, M. Blaha, W. Premerlani, F. Eddy, and W. Lorensen.Object-Oriented Modeling and Design. Prentice-Hall, Inc., 1991.

[14] L-E. Stacke, D. Fritzson, and P. Nordling. BEAST—a rolling bearingsimulation tool. Proc. Instn Mech. Engrs, part K, Journal of Multi-bodyDynamics, 213:63–71, 1999.

[15] Techplot - powerful analysis and visualization software, 2010.http://www.techplot.com.

[16] TNI-Software. Cosimate co-simulation software. Homepage, 2008.

[17] M. Woo, J. Neider, and T. Davis. OpenGL Programming Guide. Addison-Wesley Publishing Company, Inc., 2nd edition, 1998.

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Department of Computer and Information Science Linköpings universitet

Dissertations

Linköping Studies in Science and Technology

No 14 Anders Haraldsson: A Program Manipulation System Based on Partial Evaluation, 1977, ISBN 91-7372-144-1.

No 17 Bengt Magnhagen: Probability Based Verification of Time Margins in Digital Designs, 1977, ISBN 91-7372-157-3.

No 18 Mats Cedwall: Semantisk analys av process-beskrivningar i naturligt språk, 1977, ISBN 91- 7372-168-9.

No 22 Jaak Urmi: A Machine Independent LISP Compiler and its Implications for Ideal Hardware, 1978, ISBN 91-7372-188-3.

No 33 Tore Risch: Compilation of Multiple File Queries in a Meta-Database System 1978, ISBN 91- 7372-232-4.

No 51 Erland Jungert: Synthesizing Database Structures from a User Oriented Data Model, 1980, ISBN 91-7372-387-8.

No 54 Sture Hägglund: Contributions to the Development of Methods and Tools for Interactive Design of Applications Software, 1980, ISBN 91-7372-404-1.

No 55 Pär Emanuelson: Performance Enhancement in a Well-Structured Pattern Matcher through Partial Evaluation, 1980, ISBN 91-7372-403-3.

No 58 Bengt Johnsson, Bertil Andersson: The Human-Computer Interface in Commercial Systems, 1981, ISBN 91-7372-414-9.

No 69 H. Jan Komorowski: A Specification of an Abstract Prolog Machine and its Application to Partial Evaluation, 1981, ISBN 91-7372-479-3.

No 71 René Reboh: Knowledge Engineering Techniques and Tools for Expert Systems, 1981, ISBN 91-7372-489-0.

No 77 Östen Oskarsson: Mechanisms of Modifiability in large Software Systems, 1982, ISBN 91- 7372-527-7.

No 94 Hans Lunell: Code Generator Writing Systems, 1983, ISBN 91-7372-652-4.

No 97 Andrzej Lingas: Advances in Minimum Weight Triangulation, 1983, ISBN 91-7372-660-5.

No 109 Peter Fritzson: Towards a Distributed Programming Environment based on Incremental Compilation, 1984, ISBN 91-7372-801-2.

No 111 Erik Tengvald: The Design of Expert Planning Systems. An Experimental Operations Planning System for Turning, 1984, ISBN 91-7372- 805-5.

No 155 Christos Levcopoulos: Heuristics for Minimum Decompositions of Polygons, 1987, ISBN 91-7870-133-3.

No 165 James W. Goodwin: A Theory and System for Non-Monotonic Reasoning, 1987, ISBN 91-7870-183-X.

No 170 Zebo Peng: A Formal Methodology for Automated Synthesis of VLSI Systems, 1987, ISBN 91-7870-225-9.

No 174 Johan Fagerström: A Paradigm and System for Design of Distributed Systems, 1988, ISBN 91-7870-301-8.

No 192 Dimiter Driankov: Towards a Many Valued Logic of Quantified Belief, 1988, ISBN 91-7870-374-3.

No 213 Lin Padgham: Non-Monotonic Inheritance for an Object Oriented Knowledge Base, 1989, ISBN 91-7870-485-5.

No 214 Tony Larsson: A Formal Hardware Description and Verification Method, 1989, ISBN 91-7870-517-7.

No 221 Michael Reinfrank: Fundamentals and Logical Foundations of Truth Maintenance, 1989, ISBN 91-7870-546-0.

No 239 Jonas Löwgren: Knowledge-Based Design Support and Discourse Management in User Interface Management Systems, 1991, ISBN 91-7870-720-X.

No 244 Henrik Eriksson: Meta-Tool Support for Knowledge Acquisition, 1991, ISBN 91-7870-746-3.

No 252 Peter Eklund: An Epistemic Approach to Interactive Design in Multiple Inheritance Hierarchies, 1991, ISBN 91-7870-784-6.

No 258 Patrick Doherty: NML3 - A Non-Monotonic Formalism with Explicit Defaults, 1991, ISBN 91-7870-816-8.

No 260 Nahid Shahmehri: Generalized Algorithmic Debugging, 1991, ISBN 91-7870-828-1.

No 264 Nils Dahlbäck: Representation of Discourse-Cognitive and Computational Aspects, 1992, ISBN 91-7870-850-8.

No 265 Ulf Nilsson: Abstract Interpretations and Abstract Machines: Contributions to a Methodology for the Implementation of Logic Programs, 1992, ISBN 91-7870-858-3.

No 270 Ralph Rönnquist: Theory and Practice of Tense-bound Object References, 1992, ISBN 91-7870-873-7.

No 273 Björn Fjellborg: Pipeline Extraction for VLSI Data Path Synthesis, 1992, ISBN 91-7870-880-X.

No 276 Staffan Bonnier: A Formal Basis for Horn Clause Logic with External Polymorphic Functions, 1992, ISBN 91-7870-896-6.

No 277 Kristian Sandahl: Developing Knowledge Manage-ment Systems with an Active Expert Methodology, 1992, ISBN 91-7870-897-4.

No 281 Christer Bäckström: Computational Complexity of Reasoning about Plans, 1992, ISBN 91-7870-979-2.

No 292 Mats Wirén: Studies in Incremental Natural Language Analysis, 1992, ISBN 91-7871-027-8.

No 297 Mariam Kamkar: Interprocedural Dynamic Slicing with Applications to Debugging and Testing, 1993, ISBN 91-7871-065-0.

No 302 Tingting Zhang: A Study in Diagnosis Using Classification and Defaults, 1993, ISBN 91-7871-078-2

No 312 Arne Jönsson: Dialogue Management for Natural Language Interfaces - An Empirical Approach, 1993, ISBN 91-7871-110-X.

No 338 Simin Nadjm-Tehrani: Reactive Systems in Physical Environments: Compositional Modelling and Frame-work for Verification, 1994, ISBN 91-7871-237-8.

No 371 Bengt Savén: Business Models for Decision Support and Learning. A Study of Discrete-Event Manufacturing Simulation at Asea/ABB 1968-1993, 1995, ISBN 91-7871-494-X.

No 375 Ulf Söderman: Conceptual Modelling of Mode Switching Physical Systems, 1995, ISBN 91-7871-516-4.

No 383 Andreas Kågedal: Exploiting Groundness in Logic Programs, 1995, ISBN 91-7871-538-5.

No 396 George Fodor: Ontological Control, Description, Identification and Recovery from Problematic Control Situations, 1995, ISBN 91-7871-603-9.

No 413 Mikael Pettersson: Compiling Natural Semantics, 1995, ISBN 91-7871-641-1.

No 414 Xinli Gu: RT Level Testability Improvement by Testability Analysis and Transformations, 1996, ISBN 91-7871-654-3.

No 416 Hua Shu: Distributed Default Reasoning, 1996, ISBN 91-7871-665-9.

No 429 Jaime Villegas: Simulation Supported Industrial Training from an Organisational Learning Perspective - Development and Evaluation of the SSIT Method, 1996, ISBN 91-7871-700-0.

No 431 Peter Jonsson: Studies in Action Planning: Algorithms and Complexity, 1996, ISBN 91-7871-704-3.

No 437 Johan Boye: Directional Types in Logic Programming, 1996, ISBN 91-7871-725-6.

No 439 Cecilia Sjöberg: Activities, Voices and Arenas: Participatory Design in Practice, 1996, ISBN 91-7871-728-0.

No 448 Patrick Lambrix: Part-Whole Reasoning in Description Logics, 1996, ISBN 91-7871-820-1.

No 452 Kjell Orsborn: On Extensible and Object-Relational Database Technology for Finite Element Analysis Applications, 1996, ISBN 91-7871-827-9.

No 459 Olof Johansson: Development Environments for Complex Product Models, 1996, ISBN 91-7871-855-4.

No 461 Lena Strömbäck: User-Defined Constructions in Unification-Based Formalisms, 1997, ISBN 91-7871-857-0.

No 462 Lars Degerstedt: Tabulation-based Logic Program-ming: A Multi-Level View of Query Answering, 1996, ISBN 91-7871-858-9.

No 475 Fredrik Nilsson: Strategi och ekonomisk styrning - En studie av hur ekonomiska styrsystem utformas och används efter företagsförvärv, 1997, ISBN 91-7871-914-3.

No 480 Mikael Lindvall: An Empirical Study of Require-ments-Driven Impact Analysis in Object-Oriented Software Evolution, 1997, ISBN 91-7871-927-5.

No 485 Göran Forslund: Opinion-Based Systems: The Coop-erative Perspective on Knowledge-Based Decision Support, 1997, ISBN 91-7871-938-0.

No 494 Martin Sköld: Active Database Management Systems for Monitoring and Control, 1997, ISBN 91-7219-002-7.

No 495 Hans Olsén: Automatic Verification of Petri Nets in a CLP framework, 1997, ISBN 91-7219-011-6.

No 498 Thomas Drakengren: Algorithms and Complexity for Temporal and Spatial Formalisms, 1997, ISBN 91-7219-019-1.

No 502 Jakob Axelsson: Analysis and Synthesis of Heteroge-neous Real-Time Systems, 1997, ISBN 91-7219-035-3.

No 503 Johan Ringström: Compiler Generation for Data-Parallel Programming Languages from Two-Level Semantics Specifications, 1997, ISBN 91-7219-045-0.

No 512 Anna Moberg: Närhet och distans - Studier av kom-munikationsmönster i satellitkontor och flexibla kontor, 1997, ISBN 91-7219-119-8.

No 520 Mikael Ronström: Design and Modelling of a Parallel Data Server for Telecom Applications, 1998, ISBN 91-7219-169-4.

No 522 Niclas Ohlsson: Towards Effective Fault Prevention - An Empirical Study in Software Engineering, 1998, ISBN 91-7219-176-7.

No 526 Joachim Karlsson: A Systematic Approach for Prioritizing Software Requirements, 1998, ISBN 91-7219-184-8.

No 530 Henrik Nilsson: Declarative Debugging for Lazy Functional Languages, 1998, ISBN 91-7219-197-x.

No 555 Jonas Hallberg: Timing Issues in High-Level Synthe-sis, 1998, ISBN 91-7219-369-7.

No 561 Ling Lin: Management of 1-D Sequence Data - From Discrete to Continuous, 1999, ISBN 91-7219-402-2.

No 563 Eva L Ragnemalm: Student Modelling based on Col-laborative Dialogue with a Learning Companion, 1999, ISBN 91-7219-412-X.

No 567 Jörgen Lindström: Does Distance matter? On geo-graphical dispersion in organisations, 1999, ISBN 91-7219-439-1.

No 582 Vanja Josifovski: Design, Implementation and Evaluation of a Distributed Mediator System for Data Integration, 1999, ISBN 91-7219-482-0.

No 589 Rita Kovordányi: Modeling and Simulating Inhibitory Mechanisms in Mental Image Reinterpretation - Towards Cooperative Human-Computer Creativity, 1999, ISBN 91-7219-506-1.

No 592 Mikael Ericsson: Supporting the Use of Design Knowledge - An Assessment of Commenting Agents, 1999, ISBN 91-7219-532-0.

No 593 Lars Karlsson: Actions, Interactions and Narratives, 1999, ISBN 91-7219-534-7.

No 594 C. G. Mikael Johansson: Social and Organizational Aspects of Requirements Engineering Methods - A practice-oriented approach, 1999, ISBN 91-7219-541-X.

No 595 Jörgen Hansson: Value-Driven Multi-Class Overload Management in Real-Time Database Systems, 1999, ISBN 91-7219-542-8.

No 596 Niklas Hallberg: Incorporating User Values in the Design of Information Systems and Services in the Public Sector: A Methods Approach, 1999, ISBN 91-7219-543-6.

No 597 Vivian Vimarlund: An Economic Perspective on the Analysis of Impacts of Information Technology: From Case Studies in Health-Care towards General Models and Theories, 1999, ISBN 91-7219-544-4.

No 598 Johan Jenvald: Methods and Tools in Computer-Supported Taskforce Training, 1999, ISBN 91-7219-547-9.

No 607 Magnus Merkel: Understanding and enhancing translation by parallel text processing, 1999, ISBN 91-7219-614-9.

No 611 Silvia Coradeschi: Anchoring symbols to sensory data, 1999, ISBN 91-7219-623-8.

No 613 Man Lin: Analysis and Synthesis of Reactive Systems: A Generic Layered Architecture Perspective, 1999, ISBN 91-7219-630-0.

No 618 Jimmy Tjäder: Systemimplementering i praktiken - En studie av logiker i fyra projekt, 1999, ISBN 91-7219-657-2.

No 627 Vadim Engelson: Tools for Design, Interactive Simulation, and Visualization of Object-Oriented Models in Scientific Computing, 2000, ISBN 91-7219-709-9.

No 637 Esa Falkenroth: Database Technology for Control and Simulation, 2000, ISBN 91-7219-766-8.

No 639 Per-Arne Persson: Bringing Power and Knowledge Together: Information Systems Design for Autonomy and Control in Command Work, 2000, ISBN 91-7219-796-X.

No 660 Erik Larsson: An Integrated System-Level Design for Testability Methodology, 2000, ISBN 91-7219-890-7.

No 688 Marcus Bjäreland: Model-based Execution Monitoring, 2001, ISBN 91-7373-016-5.

No 689 Joakim Gustafsson: Extending Temporal Action Logic, 2001, ISBN 91-7373-017-3.

No 720 Carl-Johan Petri: Organizational Information Provi-sion - Managing Mandatory and Discretionary Use of Information Technology, 2001, ISBN-91-7373-126-9.

No 724 Paul Scerri: Designing Agents for Systems with Ad-justable Autonomy, 2001, ISBN 91 7373 207 9.

No 725 Tim Heyer: Semantic Inspection of Software Artifacts: From Theory to Practice, 2001, ISBN 91 7373 208 7.

No 726 Pär Carlshamre: A Usability Perspective on Require-ments Engineering - From Methodology to Product Development, 2001, ISBN 91 7373 212 5.

No 732 Juha Takkinen: From Information Management to Task Management in Electronic Mail, 2002, ISBN 91 7373 258 3.

No 745 Johan Åberg: Live Help Systems: An Approach to Intelligent Help for Web Information Systems, 2002, ISBN 91-7373-311-3.

No 746 Rego Granlund: Monitoring Distributed Teamwork Training, 2002, ISBN 91-7373-312-1.

No 757 Henrik André-Jönsson: Indexing Strategies for Time Series Data, 2002, ISBN 917373-346-6.

No 747 Anneli Hagdahl: Development of IT-supported Interorganisational Collaboration - A Case Study in the Swedish Public Sector, 2002, ISBN 91-7373-314-8.

No 749 Sofie Pilemalm: Information Technology for Non-Profit Organisations - Extended Participatory Design of an Information System for Trade Union Shop Stewards, 2002, ISBN 91-7373-318-0.

No 765 Stefan Holmlid: Adapting users: Towards a theory of use quality, 2002, ISBN 91-7373-397-0.

No 771 Magnus Morin: Multimedia Representations of Dis-tributed Tactical Operations, 2002, ISBN 91-7373-421-7.

No 772 Pawel Pietrzak: A Type-Based Framework for Locat-ing Errors in Constraint Logic Programs, 2002, ISBN 91-7373-422-5.

No 758 Erik Berglund: Library Communication Among Pro-grammers Worldwide, 2002, ISBN 91-7373-349-0.

No 774 Choong-ho Yi: Modelling Object-Oriented Dynamic Systems Using a Logic-Based Framework, 2002, ISBN 91-7373-424-1.

No 779 Mathias Broxvall: A Study in the Computational Complexity of Temporal Reasoning, 2002, ISBN 91-7373-440-3.

No 793 Asmus Pandikow: A Generic Principle for Enabling Interoperability of Structured and Object-Oriented Analysis and Design Tools, 2002, ISBN 91-7373-479-9.

No 785 Lars Hult: Publika Informationstjänster. En studie av den Internetbaserade encyklopedins bruksegenska-per, 2003, ISBN 91-7373-461-6.

No 800 Lars Taxén: A Framework for the Coordination of Complex Systems´ Development, 2003, ISBN 91-7373-604-X

No 808 Klas Gäre: Tre perspektiv på förväntningar och förändringar i samband med införande av informationssystem, 2003, ISBN 91-7373-618-X.

No 821 Mikael Kindborg: Concurrent Comics - programming of social agents by children, 2003, ISBN 91-7373-651-1.

No 823 Christina Ölvingson: On Development of Information Systems with GIS Functionality in Public Health Informatics: A Requirements Engineering Approach, 2003, ISBN 91-7373-656-2.

No 828 Tobias Ritzau: Memory Efficient Hard Real-Time Garbage Collection, 2003, ISBN 91-7373-666-X.

No 833 Paul Pop: Analysis and Synthesis of Communication-Intensive Heterogeneous Real-Time Systems, 2003, ISBN 91-7373-683-X.

No 852 Johan Moe: Observing the Dynamic Behaviour of Large Distributed Systems to Improve Development and Testing – An Empirical Study in Software Engineering, 2003, ISBN 91-7373-779-8.

No 867 Erik Herzog: An Approach to Systems Engineering Tool Data Representation and Exchange, 2004, ISBN 91-7373-929-4.

No 872 Aseel Berglund: Augmenting the Remote Control: Studies in Complex Information Navigation for Digital TV, 2004, ISBN 91-7373-940-5.

No 869 Jo Skåmedal: Telecommuting’s Implications on Travel and Travel Patterns, 2004, ISBN 91-7373-935-9.

No 870 Linda Askenäs: The Roles of IT - Studies of Organising when Implementing and Using Enterprise Systems, 2004, ISBN 91-7373-936-7.

No 874 Annika Flycht-Eriksson: Design and Use of Ontolo-gies in Information-Providing Dialogue Systems, 2004, ISBN 91-7373-947-2.

No 873 Peter Bunus: Debugging Techniques for Equation-Based Languages, 2004, ISBN 91-7373-941-3.

No 876 Jonas Mellin: Resource-Predictable and Efficient Monitoring of Events, 2004, ISBN 91-7373-956-1.

No 883 Magnus Bång: Computing at the Speed of Paper: Ubiquitous Computing Environments for Healthcare Professionals, 2004, ISBN 91-7373-971-5

No 882 Robert Eklund: Disfluency in Swedish human-human and human-machine travel booking di-alogues, 2004, ISBN 91-7373-966-9.

No 887 Anders Lindström: English and other Foreign Linguistic Elements in Spoken Swedish. Studies of Productive Processes and their Modelling using Finite-State Tools, 2004, ISBN 91-7373-981-2.

No 889 Zhiping Wang: Capacity-Constrained Production-in-ventory systems - Modelling and Analysis in both a traditional and an e-business context, 2004, ISBN 91-85295-08-6.

No 893 Pernilla Qvarfordt: Eyes on Multimodal Interaction, 2004, ISBN 91-85295-30-2.

No 910 Magnus Kald: In the Borderland between Strategy and Management Control - Theoretical Framework and Empirical Evidence, 2004, ISBN 91-85295-82-5.

No 918 Jonas Lundberg: Shaping Electronic News: Genre Perspectives on Interaction Design, 2004, ISBN 91-85297-14-3.

No 900 Mattias Arvola: Shades of use: The dynamics of interaction design for sociable use, 2004, ISBN 91-85295-42-6.

No 920 Luis Alejandro Cortés: Verification and Scheduling Techniques for Real-Time Embedded Systems, 2004, ISBN 91-85297-21-6.

No 929 Diana Szentivanyi: Performance Studies of Fault-Tolerant Middleware, 2005, ISBN 91-85297-58-5.

No 933 Mikael Cäker: Management Accounting as Constructing and Opposing Customer Focus: Three Case Studies on Management Accounting and Customer Relations, 2005, ISBN 91-85297-64-X.

No 937 Jonas Kvarnström: TALplanner and Other Extensions to Temporal Action Logic, 2005, ISBN 91-85297-75-5.

No 938 Bourhane Kadmiry: Fuzzy Gain-Scheduled Visual Servoing for Unmanned Helicopter, 2005, ISBN 91-85297-76-3.

No 945 Gert Jervan: Hybrid Built-In Self-Test and Test Generation Techniques for Digital Systems, 2005, ISBN: 91-85297-97-6.

No 946 Anders Arpteg: Intelligent Semi-Structured Informa-tion Extraction, 2005, ISBN 91-85297-98-4.

No 947 Ola Angelsmark: Constructing Algorithms for Con-straint Satisfaction and Related Problems - Methods and Applications, 2005, ISBN 91-85297-99-2.

No 963 Calin Curescu: Utility-based Optimisation of Resource Allocation for Wireless Networks, 2005, ISBN 91-85457-07-8.

No 972 Björn Johansson: Joint Control in Dynamic Situations, 2005, ISBN 91-85457-31-0.

No 974 Dan Lawesson: An Approach to Diagnosability Analysis for Interacting Finite State Systems, 2005, ISBN 91-85457-39-6.

No 979 Claudiu Duma: Security and Trust Mechanisms for Groups in Distributed Services, 2005, ISBN 91-85457-54-X.

No 983 Sorin Manolache: Analysis and Optimisation of Real-Time Systems with Stochastic Behaviour, 2005, ISBN 91-85457-60-4.

No 986 Yuxiao Zhao: Standards-Based Application Integration for Business-to-Business Communications, 2005, ISBN 91-85457-66-3.

No 1004 Patrik Haslum: Admissible Heuristics for Automated Planning, 2006, ISBN 91-85497-28-2.

No 1005 Aleksandra Tešanovic: Developing Reusable and Reconfigurable Real-Time Software using Aspects and Components, 2006, ISBN 91-85497-29-0.

No 1008 David Dinka: Role, Identity and Work: Extending the design and development agenda, 2006, ISBN 91-85497-42-8.

No 1009 Iakov Nakhimovski: Contributions to the Modeling and Simulation of Mechanical Systems with Detailed Contact Analysis, 2006, ISBN 91-85497-43-X.

No 1013 Wilhelm Dahllöf: Exact Algorithms for Exact Satisfiability Problems, 2006, ISBN 91-85523-97-6.

No 1016 Levon Saldamli: PDEModelica - A High-Level Lan-guage for Modeling with Partial Differential Equa-tions, 2006, ISBN 91-85523-84-4.

No 1017 Daniel Karlsson: Verification of Component-based Embedded System Designs, 2006, ISBN 91-85523-79-8

No 1018 Ioan Chisalita: Communication and Networking Techniques for Traffic Safety Systems, 2006, ISBN 91-85523-77-1.

No 1019 Tarja Susi: The Puzzle of Social Activity - The Significance of Tools in Cognition and Cooperation, 2006, ISBN 91-85523-71-2.

No 1021 Andrzej Bednarski: Integrated Optimal Code Gener-ation for Digital Signal Processors, 2006, ISBN 91-85523-69-0.

No 1022 Peter Aronsson: Automatic Parallelization of Equa-tion-Based Simulation Programs, 2006, ISBN 91-85523-68-2.

No 1030 Robert Nilsson: A Mutation-based Framework for Automated Testing of Timeliness, 2006, ISBN 91-85523-35-6.

No 1034 Jon Edvardsson: Techniques for Automatic Generation of Tests from Programs and Specifications, 2006, ISBN 91-85523-31-3.

No 1035 Vaida Jakoniene: Integration of Biological Data, 2006, ISBN 91-85523-28-3.

No 1045 Genevieve Gorrell: Generalized Hebbian Algorithms for Dimensionality Reduction in Natural Language Processing, 2006, ISBN 91-85643-88-2.

No 1051 Yu-Hsing Huang: Having a New Pair of Glasses - Applying Systemic Accident Models on Road Safety, 2006, ISBN 91-85643-64-5.

No 1054 Åsa Hedenskog: Perceive those things which cannot be seen - A Cognitive Systems Engineering perspective on requirements management, 2006, ISBN 91-85643-57-2.

No 1061 Cécile Åberg: An Evaluation Platform for Semantic Web Technology, 2007, ISBN 91-85643-31-9.

No 1073 Mats Grindal: Handling Combinatorial Explosion in Software Testing, 2007, ISBN 978-91-85715-74-9.

No 1075 Almut Herzog: Usable Security Policies for Runtime Environments, 2007, ISBN 978-91-85715-65-7.

No 1079 Magnus Wahlström: Algorithms, measures, and upper bounds for Satisfiability and related problems, 2007, ISBN 978-91-85715-55-8.

No 1083 Jesper Andersson: Dynamic Software Architectures, 2007, ISBN 978-91-85715-46-6.

No 1086 Ulf Johansson: Obtaining Accurate and Comprehensible Data Mining Models - An Evolutionary Approach, 2007, ISBN 978-91-85715-34-3.

No 1089 Traian Pop: Analysis and Optimisation of Distributed Embedded Systems with Heterogeneous Scheduling Policies, 2007, ISBN 978-91-85715-27-5.

No 1091 Gustav Nordh: Complexity Dichotomies for CSP-related Problems, 2007, ISBN 978-91-85715-20-6.

No 1106 Per Ola Kristensson: Discrete and Continuous Shape Writing for Text Entry and Control, 2007, ISBN 978-91-85831-77-7.

No 1110 He Tan: Aligning Biomedical Ontologies, 2007, ISBN 978-91-85831-56-2.

No 1112 Jessica Lindblom: Minding the body - Interacting so-cially through embodied action, 2007, ISBN 978-91-85831-48-7.

No 1113 Pontus Wärnestål: Dialogue Behavior Management in Conversational Recommender Systems, 2007, ISBN 978-91-85831-47-0.

No 1120 Thomas Gustafsson: Management of Real-Time Data Consistency and Transient Overloads in Embedded Systems, 2007, ISBN 978-91-85831-33-3.

No 1127 Alexandru Andrei: Energy Efficient and Predictable Design of Real-time Embedded Systems, 2007, ISBN 978-91-85831-06-7.

No 1139 Per Wikberg: Eliciting Knowledge from Experts in Modeling of Complex Systems: Managing Variation and Interactions, 2007, ISBN 978-91-85895-66-3.

No 1143 Mehdi Amirijoo: QoS Control of Real-Time Data Services under Uncertain Workload, 2007, ISBN 978-91-85895-49-6.

No 1150 Sanny Syberfeldt: Optimistic Replication with For-ward Conflict Resolution in Distributed Real-Time Databases, 2007, ISBN 978-91-85895-27-4.

No 1155 Beatrice Alenljung: Envisioning a Future Decision Support System for Requirements Engineering - A Holistic and Human-centred Perspective, 2008, ISBN 978-91-85895-11-3.

No 1156 Artur Wilk: Types for XML with Application to Xcerpt, 2008, ISBN 978-91-85895-08-3.

No 1183 Adrian Pop: Integrated Model-Driven Development Environments for Equation-Based Object-Oriented Languages, 2008, ISBN 978-91-7393-895-2.

No 1185 Jörgen Skågeby: Gifting Technologies - Ethnographic Studies of End-users and Social Media Sharing, 2008, ISBN 978-91-7393-892-1.

No 1187 Imad-Eldin Ali Abugessaisa: Analytical tools and information-sharing methods supporting road safety organizations, 2008, ISBN 978-91-7393-887-7.

No 1204 H. Joe Steinhauer: A Representation Scheme for De-scription and Reconstruction of Object Configurations Based on Qualitative Relations, 2008, ISBN 978-91-7393-823-5.

No 1222 Anders Larsson: Test Optimization for Core-based System-on-Chip, 2008, ISBN 978-91-7393-768-9.

No 1238 Andreas Borg: Processes and Models for Capacity Requirements in Telecommunication Systems, 2009, ISBN 978-91-7393-700-9.

No 1240 Fredrik Heintz: DyKnow: A Stream-Based Know-ledge Processing Middleware Framework, 2009, ISBN 978-91-7393-696-5.

No 1241 Birgitta Lindström: Testability of Dynamic Real-Time Systems, 2009, ISBN 978-91-7393-695-8.

No 1244 Eva Blomqvist: Semi-automatic Ontology Construc-tion based on Patterns, 2009, ISBN 978-91-7393-683-5.

No 1249 Rogier Woltjer: Functional Modeling of Constraint Management in Aviation Safety and Command and Control, 2009, ISBN 978-91-7393-659-0.

No 1260 Gianpaolo Conte: Vision-Based Localization and Guidance for Unmanned Aerial Vehicles, 2009, ISBN 978-91-7393-603-3.

No 1262 AnnMarie Ericsson: Enabling Tool Support for For-mal Analysis of ECA Rules, 2009, ISBN 978-91-7393-598-2.

No 1266 Jiri Trnka: Exploring Tactical Command and Control: A Role-Playing Simulation Approach, 2009, ISBN 978-91-7393-571-5.

No 1268 Bahlol Rahimi: Supporting Collaborative Work through ICT - How End-users Think of and Adopt Integrated Health Information Systems, 2009, ISBN 978-91-7393-550-0.

No 1274 Fredrik Kuivinen: Algorithms and Hardness Results for Some Valued CSPs, 2009, ISBN 978-91-7393-525-8.

No 1281 Gunnar Mathiason: Virtual Full Replication for Scalable Distributed Real-Time Databases, 2009, ISBN 978-91-7393-503-6.

No 1290 Viacheslav Izosimov: Scheduling and Optimization of Fault-Tolerant Distributed Embedded Systems, 2009, ISBN 978-91-7393-482-4.

No 1294 Johan Thapper: Aspects of a Constraint Optimisation Problem, 2010, ISBN 978-91-7393-464-0.

No 1306 Susanna Nilsson: Augmentation in the Wild: User Centered Development and Evaluation of Augmented Reality Applications, 2010, ISBN 978-91-7393-416-9.

No 1313 Christer Thörn: On the Quality of Feature Models, 2010, ISBN 978-91-7393-394-0.

No 1321 Zhiyuan He: Temperature Aware and Defect-Probability Driven Test Scheduling for System-on-Chip, 2010, ISBN 978-91-7393-378-0.

No 1333 David Broman: Meta-Languages and Semantics for Equation-Based Modeling and Simulation, 2010, ISBN 978-91-7393-335-3.

No 1337 Alexander Siemers: Contributions to Modelling and Visualisation of Multibody Systems Simulations with Detailed Contact Analysis, 2010, ISBN 978-91-7393-317-9.

Linköping Studies in Arts and Sciences No 504 Ing-Marie Jonsson: Social and Emotional

Characteristics of Speech-based In-Vehicle Information Systems: Impact on Attitude and Driving Behaviour, 2009, ISBN 978-91-7393-478-7.

Linköping Studies in Statistics No 9 Davood Shahsavani: Computer Experiments De-

signed to Explore and Approximate Complex Deter-ministic Models, 2008, ISBN 978-91-7393-976-8.

No 10 Karl Wahlin: Roadmap for Trend Detection and As-sessment of Data Quality, 2008, ISBN 978-91-7393-792-4.

No 11 Oleg Sysoev: Monotonic regression for large multivariate datasets, 2010, ISBN 978-91-7393-412-1.

Linköping Studies in Information Science No 1 Karin Axelsson: Metodisk systemstrukturering- att

skapa samstämmighet mellan informationssystem-arkitektur och verksamhet, 1998. ISBN-9172-19-296-8.

No 2 Stefan Cronholm: Metodverktyg och användbarhet - en studie av datorstödd metodbaserad systemutveckling, 1998, ISBN-9172-19-299-2.

No 3 Anders Avdic: Användare och utvecklare - om anveckling med kalkylprogram, 1999. ISBN-91-7219-606-8.

No 4 Owen Eriksson: Kommunikationskvalitet hos infor-mationssystem och affärsprocesser, 2000, ISBN 91-7219-811-7.

No 5 Mikael Lind: Från system till process - kriterier för processbestämning vid verksamhetsanalys, 2001, ISBN 91-7373-067-X.

No 6 Ulf Melin: Koordination och informationssystem i företag och nätverk, 2002, ISBN 91-7373-278-8.

No 7 Pär J. Ågerfalk: Information Systems Actability - Un-derstanding Information Technology as a Tool for Business Action and Communication, 2003, ISBN 91-7373-628-7.

No 8 Ulf Seigerroth: Att förstå och förändra systemutvecklingsverksamheter - en taxonomi för metautveckling, 2003, ISBN91-7373-736-4.

No 9 Karin Hedström: Spår av datoriseringens värden – Effekter av IT i äldreomsorg, 2004, ISBN 91-7373-963-

4. No 10 Ewa Braf: Knowledge Demanded for Action -

Studies on Knowledge Mediation in Organisations, 2004, ISBN 91-85295-47-7.

No 11 Fredrik Karlsson: Method Configuration method and computerized tool support, 2005, ISBN 91-85297-48-8.

No 12 Malin Nordström: Styrbar systemförvaltning - Att organisera systemförvaltningsverksamhet med hjälp av effektiva förvaltningsobjekt, 2005, ISBN 91-85297-60-7.

No 13 Stefan Holgersson: Yrke: POLIS - Yrkeskunskap, motivation, IT-system och andra förutsättningar för polisarbete, 2005, ISBN 91-85299-43-X.

No 14 Benneth Christiansson, Marie-Therese

Christiansson: Mötet mellan process och komponent - mot ett ramverk för en verksamhetsnära kravspecifikation vid anskaffning av komponentbaserade informationssystem, 2006, ISBN 91-85643-22-X.