Mathematical Approaches in Functional Safety Assessment for E/E/PE Safety-Related Software

2021 ◽  
pp. 2150043
Author(s):  
Shinji Inoue ◽  
Takaji Fujiwara ◽  
Shigeru Yamada
Keyword(s):  
Software Reliability ◽  
Safety Assessment ◽  
Assessment Method ◽  
Functional Safety ◽  
Reliability Modeling ◽  
Software Failure ◽  
Safety Integrity Level ◽  
Iec 61508 ◽  
Systematic Failure ◽  
Quantitative Safety Assessment

Safety integrity level (SIL)-based functional safety assessment is widely required in designing safety functions and checking their validity of electrical/electronic/programmable electronic (E/E/PE) safety-related systems after being issued IEC 61508 in 2010. For the hardware of E/E/PE safety-related systems, quantitative functional safety assessment based on target failure measures is needed for deciding or allocating the level of SIL. On the other hand, IEC 61508 does not provide any quantitative safety assessment method for allocating SIL for the software of E/E/PE safety-related systems because the software failure is treated as a systematic failure in IEC 61508. We discuss the needfulness of quantitative safety assessment for software of E/E/PE safety-related systems and propose mathematical fundamentals for conducting quantitative SIL-based safety assessment for the software of E/E/PE safety-related systems by applying the notion of software reliability modeling and assessment technologies. We show numerical examples for explaining how to use our approaches.

scholarly journals Application of Software Reliability Model for Safety Assessment of E/E/PE Safety-Related Software

2021 ◽  
Vol 6 (4) ◽  
pp. 1044-1054
Author(s):  
Shinji Inoue ◽  
Takaji Fujiwara ◽  
Shigeru Yamada
Keyword(s):  
Software Reliability ◽  
Safety Assessment ◽  
Quantitative Information ◽  
Software Systems ◽  
Testing Time ◽  
Software Safety ◽  
Time Duration ◽  
Reliability Modeling ◽  
Safety Integrity Level ◽  
Iec 61508

Quantitative and analytical safety assessment methods of E/E/PE safety-related software systems based on the SIL defined by IEC 61508 have been proposed. IEC 61508 does not provide us with quantitative and analytical methods for safety assessment of the software. Our methods give us quantitative information on safety measures for deciding the safety integrity level and testing time duration for achieving certain safety integrity level of E/E/PE software, respectively. Our stochastic modeling approaches are based on software reliability modeling and software reliability assessment techniques. Numerical examples for our methods have been shown for explaining how to use our software safety assessment approaches conforming IEC 61508.

scholarly journals A Functional Safety Assessment Methodology for Explosion Protection with Application to a Variable Frequency Drive System

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7872
Author(s):  
Shiguang Li ◽  
Xiaojie Wu
Keyword(s):  
Safety Assessment ◽  
Assessment Method ◽  
Variable Frequency ◽  
International Electrotechnical Commission ◽  
Functional Safety ◽  
Variable Frequency Drive ◽  
Safety Devices ◽  
Safety Integrity Level ◽  
Protection Technology ◽  
Explosion Protection

Modern explosion protection equipment, protected by traditional explosion protection technology (as defined by the international electrotechnical commission (IEC) publication IEC60079-ff series standards) and electrical/electronic/programmable electronic (E/E/PE) safety-related systems, is becoming ever more complex in coal mine development and petrochemical industry; thus, the possibility of failures in their operation is also growing. It is well-known that E/E/PE safety-related systems can be used to actively control dangerous sources, with real and expected levels of reliability, if they have been qualified according to the IEC61508-ff series standards. To uniformly evaluate the safety integrity level (SIL) of the explosion protection function of traditional explosion protection technology and E/E/PE safety-related system technology, this study analyzed the ability of these types of protection to remove the ignition risk residual, evaluating the failure rates of safety devices. The key objective of this paper is the presentation of a new equipment protection level (EPL) assessment method for explosion protection equipment based on a functional safety assessment. The method is applied to a variable frequency drive (VFD) system, and the results show that the EPL of the explosion protection equipment evaluated by this method is consistent with the EPL corresponding to the traditional explosion protection type of the IEC60079-ff series standard. Meanwhile, the flexible configuration of explosion protection safety devices and E/E/PE safety-related systems enables explosion protection equipment of different EPL levels to be designed.

scholarly journals Effect Of Selected Factors On The Safety Integrity Level (SIL)

2015 ◽  
Vol 35 (1) ◽  
pp. 85-98
Author(s):  
Młynarski Stanisław ◽  
Pilch Robert ◽  
Kaczor Grzegorz ◽  
Smolnik Maksymilian ◽  
Szkoda Maciej ◽  
...  
Keyword(s):  
Failure Rate ◽  
Safety Assessment ◽  
Repair Time ◽  
Functional Safety ◽  
Safety Level ◽  
Reliability Indicators ◽  
Safety Integrity Level ◽  
Iec 61508 ◽  
Technical Systems ◽  
The Impact

Abstract The presented paper concerns the functional safety problems of technical systems. The characteristics of safety assessment, described in IEC 61508 standard are an introduction to the problems associated with the methodology of the calculation of Safety Integrity Levels (SIL). The parameters obtained from reliability indicators, were calculated for the purpose of assessing the impact of repair time for the elements of a given system on the SIL. The calculated values of failure rate and the probability of dangerous failure show the sensitivity of the system at different time to repair values for various reliability-wise configurations. The indicators characterizing the safety level, calculated of the system with no repair time are the basis for demonstrating the influence of repair on the safety integrity level.

Markovian Multiple Change-Point Modeling for Software Reliability Assessment

2020 ◽  
Vol 27 (06) ◽  
pp. 2050017
Author(s):  
Shinji Inoue ◽  
Shigeru Yamada
Keyword(s):  
Software Reliability ◽  
Change Point ◽  
Reliability Assessment ◽  
Testing Time ◽  
Modeling Framework ◽  
Reliability Modeling ◽  
Imperfect Debugging ◽  
Testing Environment ◽  
Software Failure ◽  
Testing Phase

We discuss software reliability modeling reflecting actual situation in a testing phase based on a Markovian software reliability modeling framework. Concretely, we discuss Markovian imperfect debugging modeling for software reliability assessment with multiple changes of testing environment. Testing-time changing the testing environment is called change-point. Taking into account the effect of change-point in software reliability growth modeling is expected to improve the accuracy of software reliability assessment because it is often observed that the stochastic characteristic of software failure-occurrence or fault-detection phenomenon is changed in an actual testing phase. Numerical examples for software reliability assessment based on our proposed approach are also shown by using actual software failure-occurrence time data. Further, we discuss the usefulness of considering the effect of the imperfect debugging and the multiple change-point into software reliability modeling by comparing the estimated behavior of the mean time between software failures based on our model and the existing related models.

SOFTWARE RELIABILITY ASSESSMENT USING EXPONENTIAL-TYPE CHANGE-POINT HAZARD RATE MODELS

2014 ◽  
Vol 21 (04) ◽  
pp. 1450019 ◽  
Author(s):  
SHIHO HAYASHIDA ◽  
SHINJI INOUE ◽  
SHIGERU YAMADA
Keyword(s):  
Exponential Type ◽  
Software Reliability ◽  
Change Point ◽  
Hazard Rate ◽  
Reliability Assessment ◽  
Assessment Method ◽  
Testing Environment ◽  
Software Failure ◽  
Type Change ◽  
Hazard Rate Models

We discuss software hazard rate modeling with a change of testing-environment and a software reliability assessment method based on the proposed software hazard rate models. A software hazard rate model is known as one of the important and useful mathematical models for describing the software failure-occurrence phenomenon and conducting quantitative software reliability assessment. Taking into consideration of the effect of the change in software reliability growth modeling is expected to conduct more accurate software reliability assessment because it is said that such approach enables us to conduct more plausible software reliability assessment reflecting the actual testing-environment. Especially in this paper, we develop exponential-type software hazard rate models with effect of change-point and a software reliability assessment method based on our models. Finally, we show numerical examples for our models and results of model comparisons with existing software hazard rate models by using actual data.

scholarly journals Security Aspects in Verification of the Safety Integrity Level of Distributed Control and Protection Systems

2008 ◽  
Vol 6 (3) ◽  
pp. 25-40
Author(s):  
Barnert Tomasz ◽  
Kosmowski Kazimierz ◽  
Śliwiński Marcin
Keyword(s):  
Information Security ◽  
Distributed Control ◽  
Quantitative Method ◽  
Safety Analysis ◽  
Functional Safety ◽  
Entire System ◽  
Criterion Function ◽  
Safety Integrity Level ◽  
Iec 61508 ◽  
Protection Systems

Security Aspects in Verification of the Safety Integrity Level of Distributed Control and Protection SystemsThe article addresses some important issues of the functional safety analysis, namely the safety integrity level (SIL) verification of distributed control and protection systems with regard to security aspects. A quantitative method for SIL (IEC 61508) verification, based on so called differential factors, is presented. Taking into account SIL and the evaluation assurance level (EAL), which concerns the level of information security within entire system, two parametrical criterion function is defined for the SIL verification.

scholarly journals A functional safety assessment method for cooperative automotive architecture

2021 ◽  
pp. 110991
Author(s):  
Sangeeth Kochanthara ◽  
Niels Rood ◽  
Arash Khabbaz Saberi ◽  
Loek Cleophas ◽  
Yanja Dajsuren ◽  
...  
Keyword(s):  
Safety Assessment ◽  
Assessment Method ◽  
Functional Safety
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