| 1. |
- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 2. |
- Aldea, M., et al.
(författare)
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FSF : A real-time scheduling architecture framework
- 2006
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Ingår i: 12th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS'06). - : Institute of Electrical and Electronics Engineers (IEEE). - 9780769525167 - 0769525164 ; , s. 113-124
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Konferensbidrag (refereegranskat)abstract
- Scheduling theory generally assumes that real-time systems are mostly composed of activities with hard real-time requirements. Many systems are built today by composing different applications or components in the same system, leading to a mixture of many different kinds of requirements with small parts of the system having hard real-time requirements and other larger parts with requirements for more flexible scheduling and for quality of service. Hard real-time scheduling techniques are extremely pessimistic for the latter part of the application, and consequently it is necessary to use techniques that let the system resources be fully utilized to achieve the highest possible quality. This paper presents a framework for a scheduling architecture that provides the ability to compose several applications or components into the system, and to flexibly schedule the available resources while guaranteeing hard real-time requirements. The framework (called FSF) is independent of the underlying implementation, and can run on different underlying scheduling strategies. It is based on establishing service contracts that represent the complex and flexible requirements of the applications, and which are managed by the underlying system to provide the required level of service.
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| 3. |
- Aysan, Hüseyin, et al.
(författare)
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A Cascading Redundancy Approach for Dependable Real-Time Systems
- 2009
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Ingår i: Proceedings - 15th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2009. - 9780769537870 ; , s. 467-476
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Konferensbidrag (refereegranskat)abstract
- Dependable real-time systems typically consist of tasks of multiple criticality levels and scheduling them in a fault-tolerantmanner is a challenging problem. Redundancy in the physical and temporal domains for achieving fault tolerance has been often dealt independently based on the types of errors one needs to tolerate. To our knowledge, there had been no work which tries to integrate fault tolerant scheduling and multiple redundancy mechanisms. In this paper we propose a novel cascading redundancy approach within a generic fault tolerant scheduling framework. The proposed approach is capable of tolerating errors with a wider coverage (with respect to error frequency and error types) than time and space redundancy in isolation, allows tasks with mixed criticality levels, is independent of the scheduling technique and, above all, ensures that every critical task instance can be feasibly replicated in both time and space.
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| 4. |
- Aysan, Hüseyin, et al.
(författare)
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A Generalized Task Allocation Framework for Dependable Real-Time Systems
- 2007
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Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 19th Euromicro Conference on Real-Time Systems (ECRTS 07).
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a general framework which allows the designer to specify a wide range of criteria for allocation. Major factors considered as part of our framework are mixed criticalities of tasks, schedulability, power consumption, fault-tolerance, and dependability requirements in addition to typical functional aspects such as memory constraints. This being a global optimization problem, we are forced to use meta-heuristic algorithms, and we were able to represent these requirements in a very intuitive manner by the usage of energy functions in simulated annealing. We envision the proposed methodology as a quite simple, scalable, as well as computationally effective solution covering a wide range of system architectures and solution spaces.
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| 5. |
- Aysan, Hüseyin, et al.
(författare)
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Adding the Time Dimension to Majority Voting Strategies
- 2008
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Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 14th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS'08), St. Louis, MO, United States. ; , s. 69-73
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Konferensbidrag (refereegranskat)
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| 6. |
- Aysan, Hüseyin, et al.
(författare)
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Error Modeling in Dependable Component-based Systems
- 2008
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Ingår i: Proceedings - International Computer Software and Applications Conference. - 9780769532622 ; , s. 1309-1314
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Konferensbidrag (refereegranskat)abstract
- Component-Based Development (CBD) of software, with its successes in enterprise computing, has the promise of being a good development model due to its cost effectiveness and potential for achieving high quality of components by virtue of reuse. However, for systems with dependability concerns, such as real-time systems, a major challenge in using CBD consists of predicting dependability attributes, or providing dependability assertions, based on the individual component properties and architectural aspects. In this paper, we propose a framework which aims to address this challenge. Specifically, we present a revised error classification together with error propagation aspects, and briefly sketch how to compose errormodels within the context of Component-Based Systems (CBS). The ultimate goal is to perform the analysis on a given CBS, in order to find bottle-necks in achieving dependability requirements and to provide guidelines to the designer on the usage of appropriate error detection and fault tolerance mechanisms.
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| 7. |
- Aysan, Hüseyin, et al.
(författare)
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FT-Feasibility in Fixed Priority Real-Time Scheduling
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Real-time systems typically have to satisfy complex requirements mapped to the timing attributes of the tasks that are eventually guaranteed by the underlying scheduler. These systems consist of a mix of hard and soft tasks with varying criticalities as well as associated fault tolerance (FT) requirements. Often time redundancy techniques are preferred in many embedded applications and hence it is extremely important to devise appropriate methodologies for scheduling real-time tasks under fault assumptions. Additionally, the relative criticality of tasks could undergo changes during the evolution of the system. Hence scheduling decisions under fault assumptions have to reflect all these important factors in addition to the resource constraints.In this paper we propose a framework for 'FTfeasibility', i.e., to provide a priori guarantees that all critical tasks in the system will meet their deadlines even in case of faults. Our main objective here is to ensure FTfeasibility of all critical tasks in the system and do so with minimal costs and without any fundamental changes in the scheduling paradigm. We demonstrate its applicability in scenarios where the FT strategy employed is re-execution of the affected tasks or an alternate action upon occurrence of transient faults or software design faults. We analyse a feasible set of tasks and propose methods to adapt it to varying FT requirements without modifications to the underlying scheduler. We do so by reassigning task attributes to achieve FT-feasibility while keeping the costs minimised.
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| 8. |
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| 9. |
- Aysan, Hüseyin, et al.
(författare)
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VTV -- A Voting Strategy for Real-Time Systems
- 2008
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Ingår i: Proceedings of the 14th IEEE Pacific Rim International Symposium on Dependable Computing, PRDC 2008. - 9780769534480 ; , s. 56-63
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Konferensbidrag (refereegranskat)abstract
- Real-time applications typically have to satisfy high dependability requirements and require fault tolerance in both value and time domains. A widely used approach to ensure fault tolerance in dependable systems is the N-modular redundancy (NMR) which typically uses a majority voting mechanism. However, NMR primarily focuses on producing the correct value, without taking into account the time dimension. In this paper, we propose a new approach, Voting on Time and Value (VTV), applicable to real-time systems, which extends the modular redundancy approach by explicitly considering both value and timing failures, such that correct value is produced at a correct time, under specified assumptions. We illustrate our voting approach by instantiating it in the context of the well-known triple modular redundancy (TMR) approach. Further, we present a generalized version targeting NMR that enables a high degree of customization from the user perspective.
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| 10. |
- Buiu, C, et al.
(författare)
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GENESIS - A Framework for Global Engineering of Embedded Systems
- 2008
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Ingår i: Proceedings - International Conference on Software Engineering. - New York, NY, USA : ACM. - 9781605580760 ; , s. 87-93
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Konferensbidrag (refereegranskat)abstract
- GENESIS is an European initiative involving institutions and personsfrom older and new EU members, and West Balkan countries. It aims atdeveloping a global network of research and education in embeddedsystems. The related research will be coordinated in such a way toaddress hot topics at European and global levels and willconcentrate on the fusion of embedded systems and distributedservices over the Internet. One of the main objectives of GENESIS isto develop a distributed virtual laboratory to be used in embeddedsystems research and education and this is described in detail. Thispaper presents the rationale behind this initiative and the mainactions that are proposed to fulfill the educational, and scientificobjectives of GENESIS.
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