539 research outputs found
On the Effect of Communication Delays in Failure Diagnosis of Decentralized Discrete Event Systems
No full textWe study the effect of communication delays on the performance of a coordinated decentralized architecture for failure diagnosis of untimed discrete event systems. The architecture consists of local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the system. A protocol that realizes the architecture is defined by the diagnostic information generated at the local sites, the communication rules used by the local sites, and the decision rule used by the coordinator to infer the occurrence of failures. Our prior work (Debouk et al., 2000) has addressed the performance of a set of protocols under the assumption that messages are received by the coordinator in the order in which they are sent globally. In this work we relax the abovementioned assumption. We modify the coordinator's decision rule for two of the protocols analyzed in Debouk et al. (2000) to account for the reception of out of order messages. We discover conditions on the system structure under which the modified protocols perform as well as the centralized diagnostic scheme proposed in Sampath et al. (1995).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45079/1/10626_2004_Article_5124357.pd
Review of the Latest Developments in Automotive Safety Standardization for Driving Automation Systems
No full textThe ISO 26262: Functional Safety – Road Vehicles Standard has been the de-facto automotive functional safety standard since it was first released in 2011. With the introduction of complex driving automation systems, new standardization efforts to deal with safety of these systems have been initiated to address emerging gaps such as the human/automation roles and responsibilities in the presence/absence of the driver/user, the impact of the technological limitations and the verification and validation needs of automation systems to name a few. This paper highlights some of these gaps and introduces some of the latest developments in automotive safety standardization for driving automation systems
Overview of the Second Edition of ISO 26262: Functional Safety— Road Vehicles
No full textFunctional safety is of the utmost importance in the development of safety-critical automotive systems, especially with the introduction of driver assist and automated driving systems. ISO 26262: Functional Safety – Road Vehicles, has been the de facto standard for functional safety in the automotive electronics domain since the release of its first edition in 2011. It is currently available in its second edition, published in December 2018.
In this paper, we present an overview of the standard, which applies to all activities during the safety lifecycle of system development. In the concept phase of ISO 26262, the hazard and risk assessment process focuses on identifying possible hazards caused by malfunctioning behavior of electrical/electronic (E/E) safety-related systems and mitigating them through the identification of safety goals. The design phase includes system, hardware, and software development, with requirements developed from the safety goals. ISO 26262 also prescribes the functional safety management activities to be performed during the safety lifecycle and provides requirements for the supporting processes.
In addition to presenting an overview of the standard, this paper highlights some major changes introduced in the second edition of ISO 26262
Failure diagnosis of decentralized discrete event systems.
No full textWe address the problem of failure diagnosis in discrete event systems with decentralized information. We propose a coordinated decentralized architecture consisting of local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the system. We extend the notion of diagnosability, originally introduced in Sampath et al. (IEEE Trans. on Automatic Control, Sep. 1995) for centralized systems, to the proposed coordinated decentralized architecture. We specify three protocols that realize the proposed architecture; each protocol is defined by the diagnostic information generated at the local sites, the communication rules used by the local sites, and the coordinator's decision rule. We analyze the diagnostic properties of each protocol. We state and prove conditions for a language to be diagnosable under each protocol. These conditions are verifiable off-line. The on-line diagnostic process is carried out using the diagnosers introduced in Sampath et al. or a slight variation of these diagnosers. The key features of the proposed protocols are: (i) they achieve, each under a set of assumptions, the same diagnostic performance as the centralized diagnoser; and (ii) they highlight the performance vs. complexity tradeoff that arises in coordinated decentralized architectures. The correctness of two of the protocols relies on some stringent global ordering assumption on message reception at the coordinator's site, the relaxation of which is analyzed. We present an algorithm that attempts the ordering of messages at the coordinator site without the use of timing information. We prove that the algorithm may degrade the diagnostic performance of a protocol. Moreover, the implementation of the algorithm requires considerable additional memory and processing power at the coordinator site. We also study an optimization problem in sensor selection that could be applied to the area of failure diagnosis. We formulate the sensor selection problem as a Markovian decision problem and identify one instance where the optimal solution can be analytically determined.PhDApplied SciencesSystems scienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132769/2/9990876.pd
Product Market Fit Material Serat Rami Sebagai Elemen Material Berkelanjutan Pada Penerapan Desain Furniture
No full textThe proliferation of research and applications of sustainable materials within society has seen a notable increase, leading to constant updates in product segments featuring sustainable materials. This trend is further supported by the growing awareness among the public regarding environmental degradation. Ramie fiber is one such sustainable material serving as an alternative to the dependence on cotton materials in the textile industry. Collaborating with Armonie Ronche from Universitas Padjajaran, the author undertook a series of processes to implement ramie fiber in a furniture product, emphasizing the creation of products with good market value. Over a period of four months, the development process resulted in a living room set where a combination of hemp fiber and teak wood served as the primary elements in the design, globally marketable, and modern Jengki-style furniture.Maraknya riset dan aplikasi material berkelanjutan yang digunakan oleh masyarakat semakin tinggi yang terlihat selalu muncul pembaruan pada segmen produk dengan material berkelanjutan. Hal ini juga didukung oleh tingkat kesadaran masyarakat akan kerusakan yang terjadi pada lingkungan sekitar. Serat rami merupakan salah satu material berkelanjutan sebagai alternatif dari ketergantungan penggunaan material kapas yang ada pada industri tekstil. Bekerjasama dengan Armonie Ronche dari Universitas Padjajaran penulis melakukan serangkaian proses pengimplementasian serat rami pada sebuah produk furniture dengan mengedepankan produk yang memiliki nilai jual yang baik di masyarakat. Selama empat bulan proses pengembangan didapatkan sebuah set ruang keluarga dimana padu padan antara material rami dengan material jati sebagai elemen utama dalam perancangan mebel bergaya modern jengki yang siap dipasarkan secara global
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