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- Lecturer: Mary Ann Lundteigen
- The first lecture will be held on Tuesday August 19th 8:15-11:00 in VG13
- General information about the course (motivation, learning objectives, and related information) is found here
- The lecture plan for the entire semester is found here
- Course description is found here
Two examples:
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Reliability assessments of safety-critical systems are key services provided by many consultancy companies, such as with Safetec, Lloyd's Register Consulting, and DNV-GL (link to the GL-part of the services), and Lilleaker Consulting. Manufacturers like ABB, Siemens, AkerSolutions, FMC, Kongsberg Maritime and many others need to design systems in light of reliability requirements, and also demonstrate (sometimes with assistance of the consultancy companies) that the reliability requirements are met. End users, like railway service providers like Jernbaneverket, oil companies like Statoil, Det Norske, GDF-Suez, Shell and Conoco-Phillips, and Wintershall, and other industries like smelting plants and water power suppliers must be competent to select proper system design, follow up the system performance and select the most suitable maintenance strategies to keep costs and safety within the accepetable limits.
Topics covered
With the prevailing profile of the course, there are two main subject areas of this course:
- Subject area 1: Reliability assessment methods with focus on the application with safety-critical systems (approximately 60-70% weight)
- Subject area 2: Maintenance optimization models and methods which have a broader application area (approximately 30%-40%)
Lectured topics within these three subject areas are indicated in the lecture plan below. Textbook for subject area 1 is Reliability of Safety-Critical Systems: Theory and Applications, while the compendium, Maintenance optimization lecture notes,
is available for subject area 2.
A collection of formulas is updated after each lecture. This collection may be brought to the exam.
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Subject
area
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1st hour:
- Introduction to the course
- Organization of student groups
(3 persons per group)
2nd-3rd hours
- Introduction to two case studies
- Group work and summary in
plenum
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Inform the students about the course objectives, intended learning outcomes, and practicalities.
- Give a more thorough introduction to two systems (A SIS and a windmill) where the lectured models and methods
may be applicable. - Explain and discuss the technologies involved, with focus on attributes like
reliability, availability, maintenance, and safety - Group work and summary in plenum
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Mary Ann
and Jørn
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- Introduction to
applicable
software tools:
Matlab, Maple,
(and GRIF)
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IEC 61508 is a key standard on design of safety-critical systems, when the technology used include electrical,
electronic, and programmable electronic systems. Many authority regulations Petroleum, railway, nuclear,
automotive, etc) refer to this standard, or standards that are under the "umbrella" of this standard.
The standard introduces several key concepts including equipment under control (EUC), safety integrity level (SIL),
safety lifecycle, functional safety, risk reduction factor, and many more. Safety design principles, such as
fail-safe design and architectural constraints, are also discussed.
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- Problems Chapter 1: 2,5,8,9
- Problems Chapter 2: 1, 11, 12, 19
See http://www.ntnu.edu/web/ross/books/sis/problems
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Safety-critical systems:
Development of SIL
requirements
(chapter 2, plus supplemented material:
IEC 61511-3)
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- Problems chapter 2: 21, 22, NEW (on
risk graph calibration)
See http://www.ntnu.edu/web/ross/books/sis/problems
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Students that take this course are familiar with simplified formulas for calculating the average probability of failure on demand (PFD).
The deriving of these formulas is not repeated here, but extensions are discussed, including:
- IEC 61508-6 formulas
- PDS method
- if time: Fault tree analysis (compensating for the Schwartz' inequality)
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- A SIL verification of a 1oo2 and a 1oo3 system: Comparing the results when using different approaches.
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Safety-critical systems:
Quantification of reliability
for systems operating
on demand - introducing
PetriNets
(Textbook chapter 5 and 8)
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PetriNets is an alternative approach for calculating the the the average probability of failure on demand (PFD).
PetriNets have not been much used for this particular purpose, but the approach is widely used in many
other application areas such as the modeling of communication and software. In our context,
PetriNets have got increased attention as the newest version of IEC 61508 and a new technical guideline published by ISO, the
ISO/TR 12489) mention and give application examples.
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Yiliu
(Mary Ann
at ESREL)
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- Selected
problems
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Common cause failures (CCFs) are often the main contributor to the probability of failure for redundant systems. The students
are already familiar with the beta factor model, and this model is therefore not lectured here. The focus in this lecture
will be on:
- Main attributes of CCFs, including root causes and coupling factors
- The multiple-beta factor model and its application with e.g. the PDS method.
- Methods used to determine the value of beta (checklists and similar)
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- Problems chapter 10: 3 (excluding c)), NEW PROBLEM: Application of the Humphrey's method for determining beta.
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- Selected
problems
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- Selected
problems
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A fail-safe design of a safety-critical system favors a transition to the safe state, which in most
cases is to stop the system being protected. For example, a failure in a railway
signaling system will usually result in a stop of all train traffic, while waiting on an investigation
of why the failure occurred. So, often the result is "the more safe, the more disturbances caused by
the system. It is therefore of interest to also quantify what we refer to as the spurious trip rate,
to ensure that this rate is balanced against the PFD or PFH. This lecture presents primarily the
analytical formulas for quantifying PFH.
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- Selected
problems
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Yiliu
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In this lecture the classical age, block, and minimal repair policies are introduced as a motivation for the modelling. Next we discuss how these models align to the general modelling framework, and the concept of effective failure rate.
Special emphasise will be paid on the calculation of the effective failure rate in various situations. This involves use of renewal theory, use of the law of total probability, and Markov methods.
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This lecture is an introduction to condition based maintenance, that is to say maintenance which is based on a degradation indicator of the system. It mainly concerns preventive maintenance actions which are triggered before failure, in order to avoid failure costs. This kind of maintenance actions are relevant when the failure cost is high compared with the maintenance costs and when at least one degradation indicator is available for the system. This lecture aims at i) giving an overview of useful tools to model degradation (especially continuous state space degradation, e.g. crack propagation), ii) showing how such models can be used for failures prognosis and condition based maintenance optimization.
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Anne
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18.&19.11
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Tutorials & Project
- It is not compulsory to solve problems and hand in solutions, however, problems are provided as part of the course and the tutorial hours in relation to these. The provision of problems is based on student feedback from earlier years.
- There is no compulsory project, however, the students will be organized into groups and given a topic to present in the last lecture. Having oral presentation as part of the course is also based on student feedback from earlier years.
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