| 1. |
- Asplund, Olof, et al.
(author)
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Islet Gene View-a tool to facilitate islet research
- 2022
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In: Life Science Alliance. - : Life Science Alliance, LLC. - 2575-1077. ; 5:12
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Journal article (peer-reviewed)abstract
- Characterization of gene expression in pancreatic islets and its alteration in type 2 diabetes (T2D) are vital in understanding islet function and T2D pathogenesis. We leveraged RNA sequencing and genome-wide genotyping in islets from 188 donors to create the Islet Gene View (IGW) platform to make this information easily accessible to the scientific community. Expression data were related to islet phenotypes, diabetes status, other islet-expressed genes, islet hormone-encoding genes and for expression in insulin target tissues. The IGW web application produces output graphs for a particular gene of interest. In IGW, 284 differentially expressed genes (DEGs) were identified in T2D donor islets compared with controls. Forty percent of DEGs showed cell-type enrichment and a large proportion significantly co-expressed with islet hormone-encoding genes; glucagon (GCG, 56%), amylin (IAPP, 52%), insulin (INS, 44%), and somatostatin (SST, 24%). Inhibition of two DEGs, UNC5D and SERPINE2, impaired glucose-stimulated insulin secretion and impacted cell survival in a human beta-cell model. The exploratory use of IGW could help designing more comprehensive functional follow-up studies and serve to identify therapeutic targets in T2D.
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| 2. |
- Baer, Katharina, 1984-, et al.
(author)
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Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
- 2020
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In: Engineering optimization (Print). - : Taylor & Francis. - 0305-215X .- 1029-0273. ; 52:3, s. 446-464
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Journal article (peer-reviewed)abstract
- Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.
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| 3. |
- Braun, Robert, 1984-, et al.
(author)
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Hopsan: An Open-Source Tool for Rapid Modelling and Simulation of Fluid and Mechatronic Systems
- 2020
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In: <em>Proceedings of the BATH/ASME 2020 Symposium on Fluid Power and Motion Control</em>. - 9780791883754
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Conference paper (peer-reviewed)abstract
- Hopsan is an open-source simulation package developed as a collaboration project between industry and academia. The simulation methodology is based on transmission line modelling, which provides several benefits such as linear model scalability, numerical robustness and parallel simulation. All sub-models are pre-compiled, so that no compilation is required prior to starting a simulation. Default component libraries are available for hydraulic, mechanic, pneumatic, electric and signal domains. Custom components can be written in C++ or generated from Modelica and Mathematica. Support for simulation-based optimization is provided using population-based, evolutionary or direct-search algorithms. Recent research has largely focused on co-simulation with other simulation tools. This is achieved either by using the Functional Mock-up Interface standard, or by tool-to-tool communications. This paper provides a description of the program and its features, the current status of the project, and an overview of recent and ongoing use cases from industry and academia.
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| 4. |
- Hällqvist, Robert, 1983-
(author)
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On the Realization of Credible Simulations in Aircraft Development : Efficient and Independent Validation Enabled by Automation
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Designing modern aircraft is not an easy task. Today, it is not enough to optimize aircraft subsystems at a subsystem level. Instead, a holistic approach is necessary whereby the constituent subsystems need to be designed for the best joint performance. The State-of-the-Art (SotA) in simulating and ex-changing simulation models is moving forward at a fast pace. As such, the feasible use of simulation models has increased and additional benefits can be exploited, such as analyzing coupled subsystems in simulators. Furthermore, if aircraft subsystem simulation models are to be utilized to their fullest extent, open-source tooling and the use of open standards, interoperability between domain specific modeling tools, alongside efficient and automated processes for model Verification and Validation (V&V) and credibility assessment are required.The financial and safety related risks associated with aircraft development and operation require well founded design and operational decisions. If those decisions are to be founded upon information provided by models and simulators, then the credibility of that information needs to be assessed and communicated. Today, the large number of sensors available in modern aircraft enable model validation and credibility assessment on a different scale than what has been possible up to this point. This thesis aims to identify and address challenges to allow for automated, independent, and objective methods of integrating subsystem models into simulators while assessing and conveying the constituent models aggregated credibility.The results of the work include a proposed method for presenting the individual models’ aggregated credibility in a simulator. As the communicated credibility of simulators here relies on the credibility of each included model, the assembly procedure itself cannot introduce unknown discrepancies with respect to the System of Interest (SoI). Available methods for the management, distribution, and accurate simulation of coupled models are therefore exploited and tailored to the applications of aircraft development under consideration. Finally, a framework for automated model validation is outlined and established that supports both on-line and on-line simulator credibility assessment.
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| 5. |
- Hällqvist, Robert, 1983-, et al.
(author)
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Optimal Selection of Model Validation Experiments : Guided by Coverage
- 2021
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In: Journal of Verification, Validation and Uncertainty Quantification. - New York : The American Society of Mechanical Engineers. - 2377-2158 .- 2377-2166. ; 6:3
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Journal article (peer-reviewed)abstract
- Modeling and Simulation (M&S) is seen as a means to mitigate the difficulties associated with increased system complexity, integration, and cross-couplings effects encountered during development of aircraft subsystems. As a consequence, knowledge of model validity is necessary for taking robust and justified design decisions. This paper presents a method for using coverage metrics to formulate an optimal model validation strategy. Three fundamentally different and industrially relevant use-cases are presented. The first use-case entails the successive identification of validation settings, and the second considers the simultaneous identification of n validation settings. The latter of these two use-cases is finally expanded to incorporate a secondary model-based objective to the optimization problem in a third use-case. The approach presented is designed to be scalable and generic to models of industrially relevant complexity. As a result, selecting experiments for validation is done objectively with little required manual effort.
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| 6. |
- Hällqvist, Robert, et al.
(author)
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Realizing Interoperability between MBSE Domains in Aircraft System Development
- 2022
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In: Electronics. - : MDPI. - 2079-9292. ; 11:18
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Journal article (peer-reviewed)abstract
- Establishing interoperability is an essential aspect of the often-pursued shift towards Model-Based Systems Engineering (MBSE) in, for example, aircraft development. If models are to be the primary information carriers during development, the applied methods to enable interaction between engineering domains need to be modular, reusable, and scalable. Given the long life cycles and often large and heterogeneous development organizations in the aircraft industry, a piece to the overall solution could be to rely on open standards and tools. In this paper, the standards Functional Mock-up Interface (FMI) and System Structure and Parameterization (SSP) are exploited to exchange data between the disciplines of systems simulation and geometry modeling. A method to export data from the 3D Computer Aided Design (CAD) Software (SW) CATIA in the SSP format is developed and presented. Analogously, FMI support of the Modeling & Simulation (M&S) tools OMSimulator, OpenModelica, and Dymola is utilized along with the SSP support of OMSimulator. The developed technology is put into context by means of integration with the M&S methodology for aircraft vehicle system development deployed at Saab Aeronautics. Finally, the established interoperability is demonstrated on two different industrially relevant application examples addressing varying aspects of complexity. A primary goal of the research is to prototype and demonstrate functionality, enabled by the SSP and FMI standards, that could improve on MBSE methodology implemented in industry and academia.
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| 7. |
- Hällqvist, Robert, 1983-, et al.
(author)
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Toward Objective Assessment of Simulation Predictive Capability
- 2023
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In: Journal of Aerospace Information Systems. - : American Institute of Aeronautics and Astronautics. - 1940-3151. ; 20:3, s. 152-167
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Journal article (peer-reviewed)abstract
- Two different metrics quantifying model and simulator predictive capability are formulated and evaluated; both metrics exploit results from conducted validation experiments where simulation results are compared to the corresponding measured quantities. The first metric is inspired by the modified nearest neighbor coverage metric and the second by the Kullback-Liebler divergence. The two different metrics are implemented in Python and in a here-developed general metamodel designed to be applicable for most physics-based simulation models. These two implementations together facilitate both offline and online metric evaluation. Additionally, a connection between the two, here separated, concepts of predictive capability and credibility is established and realized in the metamodel. The two implementations are, finally, evaluated in an aeronautical domain context.
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| 8. |
- Jouannet, Christopher, et al.
(author)
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SUSTAINABLE AVIATION FOR SWEDEN - TECHNOLOGY & CAPABILITY ASSESSMENT TARGETING 2045
- 2022
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In: 33rd CONGRESS OF THE INTERNATIONAL COUNCIL OF THE AERONAUTICAL SCIENCES. - 2958-4647.
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Conference paper (peer-reviewed)abstract
- The goal of this project is to analyse the possibilities offered by different technological solutions to achieve zero emission aviation, firstly in the Swedish/Nordic network context and secondly extend this to the European context. This project will investigate the potential and feasibility of new or upgraded aircraft types based on the different technologies mapped from both, various published roadmaps and national expertise from Swedish aerospace universities and companies. This involves developing aircraft conceptual designs studies and trade analysis with regards to different fuel types, propulsion technologies, structure, operations, network and fleet management, and all relevant technologies. The project will, on a common technology basis, analyse a range of zero carbon fuels and associated technologies through operational studies and optimization to accelerate the introduction of fossil free aircraft technology and choosing optimal paths for making aviation sustainable.
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| 9. |
- Jung, Taerang, et al.
(author)
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Boom energy recuperation system and control strategy for hydraulic hybrid excavators
- 2022
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In: Automation in Construction. - : ELSEVIER. - 0926-5805 .- 1872-7891. ; 135
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Journal article (peer-reviewed)abstract
- In this paper, a boom potential energy recovery hydraulic system for an excavator and its controller is proposed and evaluated. It is a trend in the construction machinery sector to adopt hybrid systems to recuperate potential energy from heavy loads. Many studies have been conducted to improve the efficiency of boom potential energy recovery. However, most of the proposed solutions have limitations regarding commercialization due to low controllability and high cost. The proposed system in this paper uses only electronically controlled hydraulic components. Different operation modes are defined to increase performance, efficiency or a balance between the two. The system is mathematically analysed to derive a control strategy that is able to increase machine efficiency and control performance while maintaining its controllability. The system and control strategy are applied to a prototype machine, a Volvo 30-ton class excavator, to verify the effectiveness of the proposed approach. Experimental results demonstrate that the working cycle becomes around 3% faster, and the fuel consumption becomes around 9% lower than the operation in non-hybrid mode.
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| 10. |
- Kindström Andersson, Karl, et al.
(author)
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System of systems lessons to be learned in the development of air power for the future : a small state’s perspective
- 2022
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Conference paper (other academic/artistic)abstract
- Sweden, as a small alliance free state with powerful neighbors, has a military history of what we nowadays call systems of systems thinking. Since the beginning of the Cold War thishas been expressed in an air force on the forefront of exploiting military innovations, not least with regard to sensor networks, datalinks, information sharing and distributed decision making. How can this history and the lessons learned come to use when future systems and technologies are to be developed to meet the uncertain future and changing threats? How does this fit with current trends such as capability-based approach and system of systemsengineering methodology? What could this mean for the development of the next generation fighter aircraft - after the Gripen E and contemporary aircraft? These questions have been studied from both a government and industry perspective, following the trend in the defense sector of a more intertwined relationship between the two, necessitated by adopting acapability view on aircraft development. This paper presents preliminary lessons identified from a case study on the project Flygvapnet 2000 (FV2000), which preceded the Net Centric Warfare era at the turn of the millennium. The analysis was based on characteristics of best practice systems of systems engineering derived from a review of literature presenting the methodology theory on capability-based approaches for analyzing, acquiring, developing, and managing military capabilities. The findings from this project will contribute to the development of systems of systems engineering methods and will spur proposals for future research.
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