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Gavel, Hampus
Publications (10 of 21) Show all publications
Eek, M., Kharrazi, S., Gavel, H. & Ölvander, J. (2015). Study of Industrially Applied Methods for Verification, Validation & Uncertainty Quantification of Simulator Models. International Journal of Modeling, Simulation, and Scientific Computing, 6(2), Article ID 1550014.
Open this publication in new window or tab >>Study of Industrially Applied Methods for Verification, Validation & Uncertainty Quantification of Simulator Models
2015 (English)In: International Journal of Modeling, Simulation, and Scientific Computing, ISSN 1793-9623, E-ISSN 1793-9615, Vol. 6, no 2, article id 1550014Article in journal (Refereed) Published
Abstract [en]

To better utilize the potential of system simulation models and simulators, industrially applicable methods for Verification, Validation and Uncertainty Quantification(VV&UQ) are crucial. This paper presents an exploratory case study of VV&UQ techniquesapplied on models integrated in aircraft system simulators at Saab Aeronauticsand in driving simulators at the Swedish National Road and Transport Research Institute(VTI). Results show that a large number of Verification and Validation (V&V)techniques are applied, some of which are promising for further development and use insimulator credibility assessment. Regarding the application of UQ, a large gap betweenacademia and this part of industry has been identified, and simplified methods areneeded. The applicability of the NASA Credibility Assessment Scale (CAS) at the studied organizations is also evaluated and it can be concluded that the CAS is consideredto be a usable tool for achieving a uniform level of V&V for all models included in asimulator, although its implementation at the studied organizations requires tailoringand coordination.

Place, publisher, year, edition, pages
World Scientific, 2015
Keywords
Simulator credibility; simulation model; verification; validation; uncertainty quantification; V&V; VV&UQ; NASA Credibility Assessment Scale
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-115105 (URN)10.1142/S1793962315500142 (DOI)000365772300005 ()
Projects
NFFP6 2013-01211
Funder
VINNOVA, NFFP6 2013-01211
Available from: 2015-03-09 Created: 2015-03-09 Last updated: 2017-12-04
Carlsson, M., Gavel, H. & Ölvander, J. (2012). Evaluating Model Uncertainty Based on Probabilistic Analysis and Component Output Uncertainty Descriptions. In: ASME (Ed.), Proceedings of the ASME 2012 International Mechanical Engineering Congress & Exposition: IMECE2012-85236. Paper presented at ASME 2012 International Mechanical Engineering Congress & Exposition, IMECE2012, 9-15 November, Houston, Texas, USA.
Open this publication in new window or tab >>Evaluating Model Uncertainty Based on Probabilistic Analysis and Component Output Uncertainty Descriptions
2012 (English)In: Proceedings of the ASME 2012 International Mechanical Engineering Congress & Exposition: IMECE2012-85236 / [ed] ASME, 2012Conference paper, Published paper (Other academic)
Abstract [en]

To support early model validation, this paper describes a method utilizing information obtained from the common practice component level validation to assess uncertainties on model top level. Initiated in previous research, a generic output uncertainty description component, intended for power-port based simulation models of physical systems, has been implemented in Modelica. A set of model components has been extended with the generic output uncertainty description, and the concept of using component level output uncertainty to assess model top level uncertainty has been applied on a simulation model of a radar liquid cooling system. The focus of this paper is on investigating the applicability of combining the output uncertainty method with probabilistic techniques, not only to provide upper and lower bounds on model uncertaintiesbut also to accompany the uncertainties with estimated probabilities.It is shown that the method may result in a significant improvement in the conditions for conducting an assessment of model uncertainties. The primary use of the method, in combination with either deterministic or probabilistic techniques, is in the early development phases when system level measurement data are scarce. The method may also be used to point out which model components contribute most to the uncertainty on model top level. Such information can be used to concentrate physical testing activities to areas where it is needed most. In this context, the method supports the concept of Virtual Testing.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85455 (URN)
Conference
ASME 2012 International Mechanical Engineering Congress & Exposition, IMECE2012, 9-15 November, Houston, Texas, USA
Available from: 2012-11-19 Created: 2012-11-19 Last updated: 2015-01-15Bibliographically approved
Carlsson, M., Andersson, H., Gavel, H. & Ölvander, J. (2012). Methodology for Development and Validation of Multipurpose Simulation Models. In: 50th AIAA Aerospace Sciences Meeting Online Proceedings including the New Horizons Forum and Aerospace Exposition (2012): . Paper presented at 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 9–12 January, 2012, Gaylord Opryland Resort & Convention Center, 9-12 January, Nashville, Tennessee. AIAA
Open this publication in new window or tab >>Methodology for Development and Validation of Multipurpose Simulation Models
2012 (English)In: 50th AIAA Aerospace Sciences Meeting Online Proceedings including the New Horizons Forum and Aerospace Exposition (2012), AIAA , 2012Conference paper, Published paper (Refereed)
Abstract [en]

This paper describes a framework for development and validation of multipurpose simulation models. The presented methodology enables reuse of models in different applications with different purposes. The scope is simulation models representing physical environment, physical aircraft systems or subsystems, avionics equipment, and electronic hardware. The methodology has been developed by a small interdisciplinary team, with experience from Modeling and Simulation (M&S) of vehicle systems as well as development of simulators for verification and training. Special care has been taken to ensure usability of the workflow and method descriptions, mainly by means of 1) a user friendly format, easy to overview and update, 2) keeping the amount of text down, and 3) providing relevant examples, templates, and checklists. A simulation model of the Environmental Control System (ECS) of a military fighter aircraft, the Saab Gripen, is used as an example to guide the reader through the workflow of developing and validating multipurpose simulation models. The methods described in the paper can be used in both military and civil applications, and are not limited to the aircraft industry.

Place, publisher, year, edition, pages
AIAA, 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74716 (URN)10.2514/6.2012-877 (DOI)
Conference
50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 9–12 January, 2012, Gaylord Opryland Resort & Convention Center, 9-12 January, Nashville, Tennessee
Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2016-04-25
Carlsson, M., Gavel, H. & Ölvander, J. (2012). Utilizing Uncertainty Information in Early Model Validation. In: AIAA (Ed.), AIAA Modeling and Simulation Technologies Conference: . Paper presented at AIAA Modeling and Simulation Technologies Conference 2012, 13-16 August, Minneapolis, Minnesota, USA.
Open this publication in new window or tab >>Utilizing Uncertainty Information in Early Model Validation
2012 (English)In: AIAA Modeling and Simulation Technologies Conference / [ed] AIAA, 2012Conference paper, Published paper (Other academic)
Abstract [en]

This paper proposes a pragmatic approach enabling early model validation activities with a limited availability of system level measurement data. The method utilizes information obtained from the common practice of component validation to assess uncertainties on model top level. Focusing on industrial applicability, the method makes use of information normally available to engineers developing simulation models of existing or not yet existing systems. This is in contrast to the traditional sensitivity analysis requiring the user to quantify component parameter uncertainties – a task which, according to the authors’ experience, may be far from intuitive. As the proposed method enables uncertainties to be defined for a component’s outputs (characteristics) rather than its inputs (parameters), it is hereby termed output uncertainty. The method is primarily intended for use in large-scale mathematical 1-D dynamic simulation models of physical systems with or without control software, typically described by Ordinary Differential Equations (ODE) or Differential Algebraic Equations (DAE).It is shown that the method may result in a significant reduction in the number of uncertain parameters that require consideration in a simulation model. The uncertainty quantification of these parameters also becomes more intuitive. Since this implies a substantial improvement in the conditions of conducting sensitivity analysis or optimization on large-scale simulation models, the method facilitates early model validation. In contrast to sensitivity analysis with respect to a model’s original component parameters, which only covers one aspect of model uncertainty, the output uncertainty method enables assessment also of other kinds of uncertainties, such as uncertainties in underlying equations or uncertainties due to model simplifications. To increase the relevance of the method, a simulation model of a radar liquid cooling system is used as an industrial application example.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-80110 (URN)10.2514/6.2012-4852 (DOI)978-162410182-3 (ISBN)
Conference
AIAA Modeling and Simulation Technologies Conference 2012, 13-16 August, Minneapolis, Minnesota, USA
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2015-01-15
Gavel, H. & Ölvander, J. (2010). A quantified and interactive relationship matrix applied to aircraft fuel system conceptual design. International Review of Aerospace Engineering (IREASE), 3(1), 9-18
Open this publication in new window or tab >>A quantified and interactive relationship matrix applied to aircraft fuel system conceptual design
2010 (English)In: International Review of Aerospace Engineering (IREASE), ISSN 1973-7459, E-ISSN 1973-7440, Vol. 3, no 1, p. 9-18Article in journal (Refereed) Published
Abstract [en]

This paper describes how the House of Quality matrix has been quantified for use in conceptual design. The House of Quality matrix is used for visualizing the relationships between subsystem design parameters and top-level requirements. The idea is then to insert quantified values of the subsystems’ characteristics as coupling elements, thus visualizing both the requirements-subsystems relationship and system performance. Here, a spreadsheet program (MS Excel) with a built-in modeling/solver tool has been used to model the subsystems. This makes the matrix interactive, thus facilitating trade studies between requirements and system design. By adding probabilistic analysis it is possible to explore the entire range of system behavior early on, rather than just focusing on one or more worst case scenarios as has previously often been the case, and thus promoting the selection of more optimal solutions. The quantitative approach also opens up for mathematically formal optimization which has been exploited by deriving Pareto fronts for visualization of conflicting objectives, one such objective being. The design application used as illustrative example is conceptual design of an aircraft fuel system.

Keywords
Relationship Matrix, Conceptual Design, Optimization, Aircraft, Fuel System.
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-62604 (URN)
Available from: 2010-11-30 Created: 2010-11-30 Last updated: 2017-12-12Bibliographically approved
Steinkellner, S., Andersson, H., Gavel, H., Lind, I. & Krus, P. (2010). Modeling and Simulation of Saab Gripens Vehicle Systems, Challenges in Processes and Data Uncertainties. Paper presented at 27th Congress of the International Councilof the Aeronautical Sciences, ICAS2010, September 19-24, Nice, France.
Open this publication in new window or tab >>Modeling and Simulation of Saab Gripens Vehicle Systems, Challenges in Processes and Data Uncertainties
Show others...
2010 (English)Conference paper, Published paper (Other academic)
Abstract [en]

In aircraft development, it is crucial to understand and evaluate behaviour, performance, safety and other aspects of subsystems before and after they are physically available for testing. Simulation models are used to gain knowledge in order to make decisions at all development stages.

This paper describes the development of Saab Gripen´s vehicle systems and some methods and challenges related to uncertainties in test and model data. The ability to handle uncertain information and lack of information is the key to success in early design. The vehicle systems comprise fuel, environment control system (ECS), hydraulic, auxiliary power, escape, electrical power and landing gear system.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-60731 (URN)
Conference
27th Congress of the International Councilof the Aeronautical Sciences, ICAS2010, September 19-24, Nice, France
Available from: 2010-10-25 Created: 2010-10-25 Last updated: 2011-05-10Bibliographically approved
Steinkellner, S., Andersson, H., Gavel, H. & Krus, P. (2009). Modeling and simulation of Saab Gripen’s vehicle systems. Paper presented at AIAA Modeling and Simulation Technologies Conference, Chicago, Illinois, Augidy 10-13.
Open this publication in new window or tab >>Modeling and simulation of Saab Gripen’s vehicle systems
2009 (English)Conference paper, Published paper (Other academic)
Abstract [en]

This paper gives an overview of the modeling and simulation work for the military aircraft JAS 39 Gripen´s vehicle systems. The vehicle systems comprise fuel, ECS, hydraulic, and auxiliary power systems and also landing gear. Vehicle systems have several modeling  challenges such as both compressible air and less compressible fluids that give stiff differential equations, gforce effects, nonlinear cavitation and saturation. It is also a complex system of integrated systems that requires models with integrated system software. Dynamic models based on physical differential equations have generally been used. The physical systems were previously modeled in Easy5 and the software in MATRIXx. Changes in tools where the physical systems are modeled in Dymola and the control algorithms are modeled in Simulink have opened up for new possibilities for more advanced and more complete system simulations. Simulations have been performed during the whole development cycle of the aircraft from concept evaluation to qualification tests. The paper gives some examples from the simulations where system performance and the internal states of the system are calculated.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-52165 (URN)
Conference
AIAA Modeling and Simulation Technologies Conference, Chicago, Illinois, Augidy 10-13
Available from: 2009-12-08 Created: 2009-12-08 Last updated: 2011-05-10Bibliographically approved
Gavel, H., Ölvander, J. & Krus, P. (2008). A quantified relationship matrix aided by optimization and probabilistic design. In: 26th Congress of the International Council of the Aeronautical Sciences,2008. Anchorage: ICAS
Open this publication in new window or tab >>A quantified relationship matrix aided by optimization and probabilistic design
2008 (English)In: 26th Congress of the International Council of the Aeronautical Sciences,2008, Anchorage: ICAS , 2008Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Anchorage: ICAS, 2008
Keywords
aircraft fuel-system, probabilistic design, optimization
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-43917 (URN)75080 (Local ID)75080 (Archive number)75080 (OAI)
Available from: 2009-10-10 Created: 2009-10-10
Gavel, H., Ölvander Andersson, J., Johansson Lundén, B. & Krus, P. (2007). Aircraft fuel system synthesis aided by interactive morphology and optimization. In: 45th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA: . Reno,USA: AIAA (AIAA-2007-0653)
Open this publication in new window or tab >>Aircraft fuel system synthesis aided by interactive morphology and optimization
2007 (English)In: 45th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA, Reno,USA: AIAA , 2007, no AIAA-2007-0653Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Reno,USA: AIAA, 2007
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-12983 (URN)
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2009-04-28
Gavel, H. (2007). On aircraft fuel systems: conceptual design and modeling. (Doctoral dissertation). : Institutionen för ekonomisk och industriell utveckling
Open this publication in new window or tab >>On aircraft fuel systems: conceptual design and modeling
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The largest and most important fluid system in an aircraft is the fuel system. Obviously, future aircraft projects involve the design of fuel system to some degree. In this project design methodologies for aircraft fuel systems are studied, with the aim to shortening the system development time.

This is done by means of illustrative examples of how optimization and the use of matrix methods, such as the morphological matrix, house of quality and the design structure matrix, have been developed and implemented at Saab Aerospace in the conceptual design of aircraft fuel systems. The methods introduce automation early in the development process and increase understanding of how top requirements regarding the aircraft level impact low-level engineering parameters such as pipe diameter, pump size, etc. The morphological matrix and the house of quality matrix are quantified, which opens up for use of design optimization and probabilistic design.

The thesis also discusses a systematic approach when building a large simulation model of a fluid system where the objective is to minimize the development time by applying a strategy that enables parallel development and collaborative engineering, and also by building the model to the correct level of detail. By correct level of detail is meant the level that yields a simulation outcome that meets the stakeholders’ expectations. The experienced gained at Saab in building a simulation model, mainly from the Gripen fuel system, but also the accumulated experience from other system models, is condensed and fitted into an overall process.

Place, publisher, year, edition, pages
Institutionen för ekonomisk och industriell utveckling, 2007
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1067
Keywords
Aircraft, morphological matrix, simulation, Saab, Gripen
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:liu:diva-11146 (URN)978-91-85643-04-2 (ISBN)
Public defence
2007-02-23, C3, Hus C, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2009-04-08
Organisations

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