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| 2. |
- Engelson, Vadim
(author)
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3D graphics and Modelica : an integrated approach
- 2000
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In: Linköping Electronic Articles in Computer and Information Science. - : Linköping University Electronic Press. - 1401-9841. ; 5:9
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Journal article (peer-reviewed)abstract
- The Modelica standard library and available Modelica tools contain some facilities for specification of 3D geometry and 3D graphics. Geometry and graphics is associated with physical objects included in simulated Modelica models. However, important graphics properties are missing from this model. In particular, physical objects cannot change their shape (geometry) and rendering features (graphics) dynamically. The physics of simulation, is often not affected by geometry of physical objects. For instance, a body is often approximated by its center of mass under certain conditions. Either simple predefined shapes or specifications of geometry via external files are used. The last facility leads to separation between the model and the corresponding graphics and geometry. Our proposal is to integrate 3D geometric and graphical features with Modelica models of physical objects. The 3D graphics information is specified explicitly via annotations containing certain graphics primitives or using instances from a specially designed geometry class library. The motivation, syntax and implementation outline for this approach are discussed in this report.
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| 3. |
- Engelson, Vadim, 1965-, et al.
(author)
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A design, simulation and visualization environment for object-oriented mechanical and multi-domain models in Modelica
- 1999
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In: 1999 IEEE International Conference on Information Visualization, Proceedings. - 0769502105 ; , s. 188-193
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Conference paper (peer-reviewed)abstract
- The complexity of mechanical and multi-domain simulation models is rapidly increasing. Therefore new methods and standards are needed for model design. A new language, Modelica, has been proposed by an international design committee as a standard, object oriented, equation based language suitable for description of the dynamics of systems containing mechanical, electrical, chemical and other types of components. However, it is complicated to describe the system models in textual form, whereas CAD systems are convenient tools for this purpose. We have designed an environment that supports the translation from CAD models to standard Modelica notation. This notation is then used for simulation and visualization. Assembly information is extracted from the CAD models, from which a Modelica model is generated. By solving equations expressed in Modelica, the system is simulated. A 3D visualization tool based on OpenGL visualizes expected and actual model behavior, as well as additional parameters. The environment has been applied for robot and flight simulation
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| 4. |
- Engelson, Vadim, 1965-
(author)
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An approach to automatic construction of graphical user interfaces for applications in scientific computing
- 1996
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Licentiate thesis (other academic/artistic)abstract
- Applications in scientific computing perform input and output of large amounts of data of complex structure. Since it is difficult to interpret these data in textual form, a graphical user interface (GUI) for data editing, browsing and visualization is required. The availability of a convenient graphical user interface plays a critical role in the use of scientific computation systems.Most approaches to generating user interfaces provide some interactive layout facility together with a specialized language for describing user interaction. Realistic automated generation approaches are largely lacking, especially for applications in the area of scientific computing.This thesis presents two approaches to automatically generating user interfaces from specifications. The first is a semi-automatic approach, that uses information from object-oriented mathematical models, together with a set of predefined elementary types and manually supplied layout and grouping information. This system is currently in industrial use for generating user interfaces that include forms, pull-down menus and pop-up windows. The current primary application is bearing simulation, which typically accepts several thousand input parameters and produces gigabytes of output data. A serious disadvantage is that some manual changes need to be made after each update of the high-level model.The second approach avoids most of the limitations of the first generation graphical user interface generating system. We have designed a tool, PDGen (Persistence and Display Generator) that automatically creates a graphical user interface from the declarations of data structures used in the application (e.g., C++ class declarations). This largely eliminates the manual update problem. Structuring and grouping information is automatically extracted from the inheritance and part-of relations in the object-oriented model and transferred to PDGen which creates the user interface. The attributes of the generated graphical user interface can be altered in various ways if necessary.This is one of very few existing practical systems for automatically generating user interfaces from type declarations and related object-oriented structure information.
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| 5. |
- Engelson, Vadim, et al.
(author)
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An Easy-to-use Generic Model Configurator for Models in Multiple Tool Formats
- 2004
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Conference paper (peer-reviewed)abstract
- Application models for simulation are usually built by combining and configuring a selection of component models into an application model. This can be done by manually editing the model text representations. However, it is usually much easier to use a graphic editor for selecting och connecting components. The MathModelica tool has such a graphic editor, adapted for components in Modelica libraries. However, since Modelica is a generic model description language, it has been possible to extend the editor to support configuration of components in other modeling tool formats, e.g. ADAMS or ANSYS. When the editor is used in this generic way, the Modelica connections and interfaces are translated into the format of the specific tool. The editor does not need to know anything about the internals of model components that are combined, just the interfaces. The configurator has successfully been used to configure and simulate mechanical bearing models as well as a wheel loader model, currently supporting three different formats: Modelica MBS, ADAMS, and ANSYS, with ongoing development for the SKF BEAST MBS model format
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| 6. |
- Engelson, Vadim, 1965-, et al.
(author)
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Automatic generation of user interfaces from data structure specifications and object-oriented application models
- 1996
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In: ECOOP ’96 — Object-Oriented Programming. - : Springer Berlin/Heidelberg. - 9783540614395 ; , s. 114-141
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Conference paper (peer-reviewed)abstract
- Applications in scientific computing operate with data of complex structure and graphical tools for data editing, browsing and visualization are necessary.Most approaches to generating user interfaces provide some interactive layout facility together with a specialized language for describing user interaction. Realistic automated generation approaches are largely lacking, especially for applications in the area of scientific computing.This paper presents two approaches to automatically generating user interfaces (that include forms, pull-down menus and pop-up windows) from specifications.The first is a semi-automatic approach, that uses information from object-oriented mathematical models, together with a set of predefined elementary types and manually supplied layout and grouping information. This system is currently in industrial use. A disadvantage is that some manual changes need to be made after each update of the model.Within the second approach we have designed a tool, PDGen (Persistence and Display Generator) that automatically creates a graphical user interface and persistence routines from the declarations of data structures used in the application (e.g., C++ class declarations). This largely eliminates the manual update problem. The attributes of the generated graphical user interface can be altered.Now structuring and grouping information is automatically extracted from the object-oriented mathematical model and transferred to PDGen. This is one of very few existing practical systems for automatically generating user interfaces from type declarations and related object-oriented structure information.
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| 7. |
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| 8. |
- Engelson, Vadim, et al.
(author)
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Generating efficient 3D graphics animation code with OpenGL from object oriented models in Mathematica
- 1997
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In: Innovation in Mathematics. ; , s. 129-136
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Conference paper (peer-reviewed)abstract
- Traditionally 3D plots of parametric functions expressed in Mathematica are computed interpretively and saved in a static form before display. This causes low graphic performance. In this paper we describe an approach to generate efficient C++/Fortran90 code from such functions. This code is linked together with a powerful 3D browsing environment and uses OpenGL with possible hardware support. Thus flexibility of interactive exploration of 3D scenes and animation options become available for the end-user. 1 Introduction 1.1 The visualization problem Numerical experiments based on mathematical models is one of the most prevalent classes of applications of high performance computers and workstations. A common problem is however to interpret and make use of numerical data produced from such experiments. High performance numerical programs usually generate vast amounts of data (in our applications 1-2 Gbyte or more).
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| 9. |
- Engelson, Vadim
(author)
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Integration of collision detection with the multibody system library in Modelica
- 2000
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In: Linköping Electronic Articles in Computer and Information Science. - : Linköping University Electronic Press. - 1401-9841. ; 5:10
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Journal article (peer-reviewed)abstract
- Collision detection and response is one of the most difficult areas in simulation of multibody systems. Two known approaches, the impulse-based method and the force-based (penalty) method, can be applied for multibody simulation in Modelica. The impulse-based method requires instantaneous modification of some variables, but such modification is not always possible in Modelica. The force-based method leads to stiff ODE, which can be handled by solvers used with Modelica. We suggest a new way to express the penalty coefficients. The force-based method, however, requires computation of penetration depth which is time-consuming.We also suggest a method that combines the distance between bodies and the penetration depth into a single quantity used for force computation.Calling external functions is a preferable method integrate collision detection algorithms with practical physical models, since body geometry is stored externally. We describe an interface with collision detection tool SOLID.
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| 10. |
- Engelson, Vadim, 1965-, et al.
(author)
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Lossless compression of high-volume numerical data from simulations
- 2000
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In: Proceedings. DCC 2000 Data Compression Conference, 2000. - : IEEE. - 0769505929
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Conference paper (peer-reviewed)abstract
- Summary form only given. We propose a lossless algorithm of delta compression (a variant of predictive coding) that attempts to predict the next point from previous points using higher-order polynomial extrapolation. In contrast to traditional predictive coding our method takes into account varying (non-equidistant) domain (typically, time) steps. To save space and guarantee lossless compression, the actual and predicted values are converted to 64-bit integers. The residual (difference between actual and predicted values) is computed as difference of integers. The unnecessary bits of the residual are truncated, e.g., 1111110101 is replaced by 10101. The length of the bit sequence (510=(000101)2) is prepended
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