| 1. |
- Islam, Md Mafijul, et al.
(author)
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Towards benchmarking of functional safety in the automotive industry
- 2013
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In: Lecture Notes in Computr Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783642387883 ; , s. 111-125
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Conference paper (peer-reviewed)abstract
- Functional safety is becoming increasingly important in the automotive industry to deal with the growing reliance on the electrical and/or electronic (E/E) systems and the associated complexities. The introduction of ISO 26262, a new standard for functional safety in road vehicles, has made it even more important to adopt a systematic approach of evaluating functional safety. However, standard assessment methods of benchmarking functional safety of automotive systems are not available as of today. This is where the BeSafe (Benchmarking of Functional Safety) project comes into the picture. BeSafe project aims to lay the foundation for benchmarking functional safety of automotive E/E systems. In this paper, we present a brief overview of the project along with the benchmark targets that we have identified as relevant for the automotive industry, assuming three abstraction layers (model, software, hardware). We then define and discuss a set of benchmark measures. Next, we propose a benchmark framework encompassing fault/error models, methods and the required tool support. This paper primarily focuses on functional safety benchmarking from the Safety Element out of Context (SEooC) viewpoint. Finally, we present some preliminary results and highlight potential future works.
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| 2. |
- Fathollah Nejad Asl, Negin, 1982, et al.
(author)
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On probabilistic analysis of disagreement in synchronous consensus protocols
- 2014
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In: 10th European Dependable Computing Conference, EDCC 2014; Newcastle upon Tyne; United Kingdom; 13 May 2014 through 16 May 2014. - 9781479938032 ; , s. 23-34
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Conference paper (peer-reviewed)abstract
- This paper presents a probabilistic analysis of disagreement for a family of simple synchronous consensus algorithms aimed at solving the 1-of-n selection problem in presence of unrestricted communication failures. In this problem, a set of n nodes are to select one common value among n proposed values. There are two possible outcomes of each node's selection process: decide to select a value or abort. We have disagreement if some nodes select the same value while other nodes decide to abort. Previous research has shown that it is impossible to guarantee agreement among the nodes subjected to an unbounded number of message losses. Our aim is to find decision algorithms for which the probability of disagreement is as low as possible. In this paper, we investigate two different decision criteria, one optimistic and one pessimistic. We assume two communication failure models, symmetric and asymmetric. For symmetric communication failures, we present the closed-form expressions for the probability of disagreement. For asymmetric failures, we analyse the algorithm using a probabilistic model checking tool. Our results show that the choice of decision criterion significantly influences the probability of disagreement for the 1-of-n selection algorithm. The optimistic decision criterion shows a lower probability of disagreement compare to the pessimistic one when the probability of message loss is less than 30% to 70%. On the other hand, the optimistic decision criterion has in general a higher maximum probability of disagreement compared to the pessimistic criterion.
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| 3. |
- Fathollah Nejad Asl, Negin, 1982, et al.
(author)
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On reliability analysis of leader election protocols for virtual traffic lights
- 2013
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In: Dependable Systems and Networks Workshop (DSN-W), 2013 43rd Annual IEEE/IFIP Conference on. - 2325-6648. - 9781479901814
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Conference paper (peer-reviewed)abstract
- This paper addresses the problem of leader electionin virtual traffic lights. A virtual traffic light (VTL) isa self-organizing traffic control system that allows road vehiclesequipped with vehicle-to-vehicle communication facilities toimplement the function of a traffic light without the supportof a roadside installation. Previous research has shown thatit is impossible to construct a leader election protocol thatguarantees agreement among the participating vehicles in thepresence of massive communication failures. The paper addressesthe problem of calculating the probability of disagreement insituations where a large number of protocol messages are lost dueto communication interference, so-called communication greyouts.To this end, we present a probabilistic analysis of a familyof simple round-based consensus algorithms that solve the 1-of-n selection problem. We propose to use these algorithms forthe core logic of a VTL leader election protocol (LEP). Ouranalysis shows that the probability of disagreement depends on:i) the number of vehicles involved in the leader election, ii) thenumber of rounds of message exchange, iii) the probability ofmessage loss, and iv) the decision criterion used by the LEP. Wepropose an optimistic and a pessimistic decision criteria for theproposed 1-of-n selection algorithms. The analysis encompass twoprobabilistic failure models, one for symmetric communicationfailures and one for asymmetric communication failures.
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| 4. |
- Fathollah Nejad Asl, Negin, 1982, et al.
(author)
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Probabilistic Analysis of a 1-of-n Selection Algorithm using a Moderately Pessimistic Decision Criterion
- 2013
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In: Proceedings of IEEE Pacific Rim International Symposium on Dependable Computing, PRDC. - 1541-0110. - 9780769551302 ; , s. 68-77
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Conference paper (peer-reviewed)abstract
- In this paper we are concerned with the fundamental problem of reaching agreement among a set of distributed processes in presence of an unbounded number of communication failures. We present a probabilistic analysis of a family of synchronous consensus algorithms that aim to solve the 1-ofn selection problem. In this problem, a set of n nodes are to select one common value among a set of n proposed values. There are two possible outcomes of each node's selection process: it can decide either to select a value, or to abort. Agreement implies that all nodes select the same value, or all nodes decide to abort. We know from previous research that it is impossible to guarantee agreement if there is no upper bound on the number of communication failures that can occur. Our aim is to study how the probability of disagreement varies for different decision criteria. The decision criterion consists of the logical expressions that determine whether a process will select a value or decide to abort based on its view of the system state. In this paper we propose and analyse a moderately pessimistic decision criterion. We compared this decision criterion with an optimistic and a pessimistic decision criterion, which we have investigated in our previous work. Our results show that the moderately pessimistic decision criterion for most configurations has a lower maximum probability of disagreement compared with the two other decision criteria. Furthermore, it provides a compromise between the optimistic and the pessimistic approaches since it reduces the probability of disagreement without increasing excessively the probability of agreeing to abort.
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