| 1. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 2. |
- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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| 3. |
- Al Mamun, Md Abdullah, 1982, et al.
(författare)
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Engineering the Hardware/Software Interface for Robotic Platforms – A Comparison of Applied Model Checking with Prolog and Alloy
- 2013
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Ingår i: Proceedings of the 4th International Workshop on Domain-Specific Languages and models for ROBotic systems.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Robotic platforms serve different use cases ranging from experiments for prototyping assistive applications up to embedded systems for realizing cyber-physical systems in various domains. We are using 1:10 scale miniature vehicles as a robotic platform to conduct research in the domain of self-driving cars and collaborative vehicle fleets. Thus, experiments with different sensors like e.g. ultra-sonic, infrared, and rotary encoders need to be prepared and realized using our vehicle platform. For each setup, we need to configure the hardware/software interface board to handle all sensors and actors. Therefore, we need to find a specific configuration setting for each pin of the interface board that can handle our current hardware setup but which is also flexible enough to support further sensors or actors for future use cases. In this paper, we show how to model the domain of the configuration space for a hardware/software interface board to enable model checking for solving the tasks of finding any, all, and the best possible pin configuration. We present results from a formal experiment applying the declarative languages Alloy and Prolog to guide the process of engineering the hardware/software interface for robotic platforms on the example of a configuration complexity up to ten pins resulting in a configuration space greater than 14.5 million possibilities. Our results show that our domain model in Alloy performs better compared to Prolog to find feasible solutions for larger configurations with an average time of 0.58s. To find the best solution, our model for Prolog performs better taking only 1.38s for the largest desired configuration; however, this important use case is currently not covered by the existing tools for the hardware used as an example in this article.
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| 4. |
- Al Mamun, Md Abdullah, 1982, et al.
(författare)
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Explicating, Understanding and Managing Technical Debt from Self-Driving Miniature Car Projects
- 2014
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Ingår i: Proceedings of the 30th IEEE International Conference on Software Maintenance and Evolution (ICSME). - Los Alamitos, CA : IEEE. - 9781479967919
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Konferensbidrag (refereegranskat)abstract
- Technical debt refers to various weaknesses in the design or implementation of a system resulting from trade-offs during software development usually for a quick release. Accumulating such debt over time without reducing it can seriously hamper the reusability and maintainability of the software. The aim of this study is to understand the state of the technical debt in the development of self-driving miniature cars so that proper actions can be planned to reduce the debt to have more reusable and maintainable software. A case study on a selected feature from two self-driving miniature car development projects is performed to assess the technical debt. Additionally, an interview study is conducted involving the developers to relate the findings of the case study with the possible root causes. The result of the study indicates that "the lack of knowledge" is not the primary reason for the accumulation of technical debt from the selected code smells. The root causes are rather in factors like time pressure followed by issues related to software/hardware integration and incomplete refactoring as well as reuse of legacy, third party, or open source code.
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| 5. |
- Al Mamun, Md Abdullah, 1982, et al.
(författare)
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MDE-based Sensor Management and Verification for a Self-Driving Miniature Vehicle
- 2013
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Ingår i: 13th ACM Workshop on Domain-Specific Modeling, DSM 2013; Indianapolis, IN; United States. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450326001
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Konferensbidrag (refereegranskat)abstract
- Innovations for today’s vehicle functions are mainly driven by software. They realize comfort systems like automated parking but also safety systems where sensors are continuously monitoring the vehicle's surroundings to brake autonomously for avoiding collisions with cars, pedestrians, or bicyclists. In simulation environments, various traffic situations with alternative sensor setups are imitated before testing them on prototypical cars. In this paper, we are presenting an MDE approach for managing different sensor setups in a cyber-physical system development environment to leverage automated model verification, support system testing, and enable code generation. For example, the models are used as the single point of truth to configure and generate sensor setups for system validations in a 3D simulation environment. After their validation, a considered sensor configuration is transformed into a constraint-satisfaction model to be solved by the logical programming language Prolog. Based on this transformation, the conformance to the embedded system specification is formally verified and possible pin assignments, for how to connect the required sensors are calculated. The approach was validated during the development of a self- driving miniature vehicle using an STM32F4-based embedded system running the real-time operating system ChibiOS as the software/hardware interface to the sensors and actors.
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| 6. |
- Berger, Christian, 1980, et al.
(författare)
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COTS-Architecture with a Real-Time OS for a Self-Driving Miniature Vehicle
- 2013
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Ingår i: Proceedings of Workshop ASCoMS (Architecting Safety in Collaborative Mobile Systems) of the 32nd International Conference on Computer Safety, Reliability and Security. ; , s. 411-422
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Konferensbidrag (refereegranskat)abstract
- The international competition 2007 DARPA Urban Challenge significantly fostered the research and development on intelligent vehicles. Recent prototypes from Google for instance are able to drive fully autonomously through the San Francisco bay area for more than 450,000km. Even if self-driving vehicles are not yet available for purchase for customers, technology spin-offs are increasingly finding their ways into today's vehicles as pedestrian collision warning system, automated parking, or adaptive cruise control with temporary lane following. Thus, the upcoming generation of software and computer engineers needs to be accordingly educated to be already familiar with the concepts and pitfalls of these complex systems. In this article, we describe the architecture of a self-driving miniature vehicle based solely on commercial-off-the-shelf (COTS) components for the hardware and the real-time operating system ChibiOS/RT for the software/hardware interface.
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| 7. |
- Aad, G., et al.
(författare)
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- 2012
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swepub:Mat__t (refereegranskat)
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