| 1. |
- Aamodt, K., et al.
(författare)
-
The ALICE experiment at the CERN LHC
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
-
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.
|
|
| 2. |
- Aldea, M., et al.
(författare)
-
FSF : A real-time scheduling architecture framework
- 2006
-
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
-
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.
|
|
| 3. |
- Aravind, Meera, et al.
(författare)
-
An Event-Based Messaging Architecture for Vehicular Internet of Things (IoT) Platforms
- 2017
-
Ingår i: Communications in Computer and Information Science, vol. 778. - Cham : Springer Verlag. - 9783319675961 ; , s. 37-46
-
Konferensbidrag (refereegranskat)abstract
- Internet of Things (IoT) has revolutionized transportation systems by connecting vehicles consequently enabling their tracking, as well as monitoring of driver activities. Such an IoT platform requires a significant amount of data to be send from the on-board vehicle to the off-board servers, contributing to high network usage. The data can be send at regular intervals or in an event-based manner whenever relevant events occur. In interval-based approach, the data is send even if it is not relevant for reporting leading to a wastage of network resources, e.g., when the data does not change considerably compared to the previously sent value. In this paper, we investigate the possibility of using an event-based architecture to send data from the on-board system to the off-board system. The results show that our event-based architecture improves the accuracy of data available at the off-board system, by a careful selection of events. Moreover, we found that our event based architecture significantly decreases the frequency of sending messages, particularly during highway driving, leading to reduced average data transfer rates. Our results enable a customer to perform trade-offs between accuracy and data transfer rates.
|
|
| 4. |
- Aysan, Hüseyin, et al.
(författare)
-
A Cascading Redundancy Approach for Dependable Real-Time Systems
- 2009
-
Ingår i: Proceedings - 15th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2009. - 9780769537870 ; , s. 467-476
-
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.
|
|
| 5. |
- Aysan, Hüseyin, et al.
(författare)
-
A Generalized Task Allocation Framework for Dependable Real-Time Systems
- 2007
-
Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 19th Euromicro Conference on Real-Time Systems (ECRTS 07).
-
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.
|
|
| 6. |
- Aysan, Hüseyin, et al.
(författare)
-
Adding the Time Dimension to Majority Voting Strategies
- 2008
-
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
-
Konferensbidrag (refereegranskat)
|
|
| 7. |
- Aysan, Hüseyin, et al.
(författare)
-
Efficient Fault Tolerant Scheduling on Controller Area Network (CAN)
- 2010
-
Ingår i: Proceedings of the 15th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2010. - Bilbao, Spain. ; , s. Art.nr 5641318-
-
Konferensbidrag (refereegranskat)abstract
- Dependable communication is becoming a critical factor due to the pervasive usage of networked embedded systems that increasingly interact with human lives in many real-time applications. Controller Area Network (CAN) has gained wider acceptance as a standard in a large number of industrial applications, mostly due to its efficient bandwidth utilization, ability to provide real-time guarantees, as well as its fault-tolerant capability. However, the native CAN fault-tolerant mechanism assumes that all messages transmitted on the bus are equally critical, which has an adverse impact on the message latencies, results in the inability to meet user defined reliability requirements, and, in some cases, even leads to violation of timing requirements. As the network potentially needs to cater to messages of multiple criticality levels (and hence varied redundancy requirements), scheduling them in an efficient fault-tolerant manner becomes an important research issue. We propose a methodology which enables the provision of appropriate guarantees in CAN scheduling of messages with mixed criticalities. The proposed approach involves definition of fault-tolerant feasibility windows of execution for critical messages, and off-line derivation of optimal message priorities that fulfill the user specified level of fault-tolerance.
|
|
| 8. |
- Aysan, Hüseyin, et al.
(författare)
-
Error Modeling in Dependable Component-based Systems
- 2008
-
Ingår i: Proceedings - International Computer Software and Applications Conference. - 9780769532622 ; , s. 1309-1314
-
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.
|
|
| 9. |
- Aysan, Hüseyin, 1982-
(författare)
-
Fault-Tolerance Strategies and Probabilistic Guarantees for Real-Time Systems
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ubiquitous deployment of embedded systems is having a substantial impact on our society, since they interact with our lives in many critical real-time applications. Typically, embedded systems used in safety or mission critical applications (e.g., aerospace, avionics, automotive or nuclear domains) work in harsh environments where they are exposed to frequent transient faults such as power supply jitter, network noise and radiation. They are also susceptible to errors originating from design and production faults. Hence, they have the design objective to maintain the properties of timeliness and functional correctness even under error occurrences. Fault-tolerance plays a crucial role towards achieving dependability, and the fundamental requirement for the design of effective and efficient fault-tolerance mechanisms is a realistic and applicable model of potential faults and their manifestations. An important factor to be considered in this context is the random nature of faults and errors, which, if addressed in the timing analysis by assuming a rigid worst-case occurrence scenario, may lead to inaccurate results. It is also important that the power, weight, space and cost constraints of embedded systems are addressed by efficiently using the available resources for fault-tolerance. This thesis presents a framework for designing predictably dependable embedded real-time systems by jointly addressing the timeliness and the reliability properties. It proposes a spectrum of fault-tolerance strategies particularly targeting embedded real-time systems. Efficient resource usage is attained by considering the diverse criticality levels of the systems' building blocks. The fault-tolerance strategies are complemented with the proposed probabilistic schedulability analysis techniques, which are based on a comprehensive stochastic fault and error model.
|
|
| 10. |
- Aysan, Hüseyin, et al.
(författare)
-
Fault Tolerant Scheduling on Control Area Network (CAN) :
- 2010
-
Ingår i: ISORC Workshops 2010 - 2010 13th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing Workshops, Vol. 2. ; , s. 226-232
-
Konferensbidrag (refereegranskat)abstract
- Dependable communications is becoming a critical factor due to the pervasive usage of networked embedded systems that increasingly interact with human lives in one way or the other in many real-time applications. Though many smaller systems are providing dependable services employing uniprocesssor solutions, stringent fault containment strategies etc., these practices are fast becoming inadequate due to the prominence of COTS in hardware and component based development(CBD) in software as well as the increased focus on building 'system of systems'. Hence the repertoire of design paradigms, methods and tools available to the developers of distributed real-time systems needs to be enhanced in multiple directions and dimensions. In future scenarios, potentially a network needs to cater to messages of multiple criticality levels (and hence varied redundancy requirements) and scheduling them in a fault tolerant manner becomes an important research issue. We address this problem in the context of Controller Area Network (CAN), which is widely used in automotive and automation domains, and describe a methodology which enables the provision of appropriate scheduling guarantees. The proposed approach involves definition of fault-tolerant windows of execution for critical messages and the derivation of message priorities based on earliest deadline first (EDF).
|
|
