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Salameh, A. & Jaradat, O. (2018). A Safety-Centric Change Management Framework by Tailoring Agile and V-Model Processes. In: 36th International System Safety Conference ISSC 2018: . Paper presented at 36th International System Safety Conference ISSC 2018, 13 Aug 2018, Phoenix, AZ, United States.
Open this publication in new window or tab >>A Safety-Centric Change Management Framework by Tailoring Agile and V-Model Processes
2018 (English)In: 36th International System Safety Conference ISSC 2018, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Safety critical systems are evolutionary and subject to preventive, perfective, corrective or adaptive changes during their lifecycle. Changes to any part of those systems can undermine the confidence in safety since changes can refute articulated claims about safety or challenge the supporting evidence on which this confidence relies. Changes to the software components are no exception. In order to maintain the confidence in the safety performance, developers must update their system and its safety case. Agile methodologies are known to embrace changes to software where agilists strive to manage changes, not to prevent them. In this paper, we introduce a novel framework in which we tailor a hybrid process of agile software development and the traditional V-model. The tailored process aims to facilitate the accommodation of non-structural changes to the software parts of safety critical systems. We illustrate our framework in the context of ISO 26262 safety standard.

Keywords
safety case, contracts, impact analysis, change management, agile software development, agile tailoring, V-model, XP, Kanban
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-40880 (URN)
Conference
36th International System Safety Conference ISSC 2018, 13 Aug 2018, Phoenix, AZ, United States
Projects
Future factories in the CloudSafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2019-04-17Bibliographically approved
Jaradat, O. (2018). Contracts-Based Maintenance of Safety Cases. (Doctoral dissertation). Västerås: Mälardalen University
Open this publication in new window or tab >>Contracts-Based Maintenance of Safety Cases
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Safety critical systems are those systems whose failure could result in loss of life, significant property damage, or damage to the environment. System safety is a major property that shall be adequately assured to avoid any severe outcomes in safety critical systems. Safety assurance should provide justified confidence that all potential risks due to system failures are either eliminated or acceptably mitigated. System developers in many domains (e.g., automotive, avionics, railways) should provide convincing arguments regarding the safe performance of their systems to a national or international regulatory authority and obtain approvals before putting the system into service.  Building 'Safety cases' is a proven technique to argue about and communicate systems' safety and it has become a common practice in many safety critical system domains. System developers use safety cases to articulate claims about how systems meet their safety requirements and objectives, collect and document items of evidence, and construct a safety argument to show how the available items of evidence support the claims.

Safety critical systems are evolutionary and constantly subject to preventive, perfective, corrective or adaptive changes during both the development and operational phases. Changes to any part of those systems can undermine the confidence in safety since changes can refute articulated claims about safety or challenge the supporting evidence on which this confidence relies. Hence, safety cases need to be built as living documents that should always be maintained to justify the safety status of the associated system and evolve as these systems evolve. However, building safety cases are costly since they require a significant amount of time and efforts to define the safety objectives, generate the required evidence and conclude the underlying logic behind the safety case arguments. Safety cases document highly dependent elements such as safety goals, assumptions and evidence. Seemingly minor changes may have a major impact. Changes to a system or its environment can necessitate a costly and painstaking impact analysis for systems and their safety cases. In addition, changes may require system developers to generate completely new items of evidence by repeating the verification activities. Therefore, changes can exacerbate the cost of producing and maintaining safety cases.  

Safety contracts have been proposed as a means for helping to manage changes. There have been works that discuss the usefulness of contracts for reusability and maintainability. However, there has been little attention on how to derive them and how exactly they can be utilised for system or safety case maintenance.

The main goal of this thesis is to support the change impact analysis as a key factor to enhance the maintainability of safety cases. We focus on utilising safety contracts to achieve this goal. To address this, we study how safety contracts can support essential factors for any useful change management process, such as (1) identifying the impacted  elements  and  those  that  are  not  impacted, (2) minimising the number of impacted  safety  case  elements, and (3) reducing the  work  needed  to  make  the  impacted  safety  case  elements valid again. The preliminary finding of our study reveals that using safety contracts can be promising to develop techniques and processes to facilitate safety case maintenance. The absence of safety case maintenance guidelines from safety standards and the lack of systematic and methodical maintenance techniques have motivated the work of this thesis. Our work is presented through a set of developed and assessed techniques, where these techniques utilise safety contracts to achieve the overall goal by various contributions. We begin by a framework for evaluation of the impact of change on safety critical systems and safety cases. Through this, we identify and highlight the most sensitive system components to a particular change. We propose new ways to associate system design elements with safety case arguments to enable traceability. How to identify and reduce the propagation of change impact is addressed subsequently.  Our research also uses safety contracts to enable through-life safety assurance by monitoring and detecting any potential mismatch between the design safety assumptions and the actual behaviour of the system during its operational phase. More specifically, we use safety contracts to capture thresholds of selected safety requirements and compare them with the runtime related data (i.e., operational data) to continuously assess and evolve the safety arguments.

In summary, our proposed techniques pave the way for cost-effective maintenance of safety cases upon preventive, perfective, corrective or adaptive changes in safety critical systems thus helping better decision support for change impact analysis.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2018
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 280
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:mdh:diva-41281 (URN)978-91-7485-417-6 (ISBN)
Public defence
2018-12-03, Kappa, Mälardalens högskola, Västerås, 09:30 (English)
Opponent
Supervisors
Projects
SafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2018-11-02 Created: 2018-11-02 Last updated: 2019-04-16Bibliographically approved
Ashjaei, S. M., Clegg, K., Corneo, L., Hawkins, R., Jaradat, O., Gulisano, V. & Nikolakopoulos, Y. (2018). Service Level Agreements for Safe and Configurable Production Environments. In: International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18: . Paper presented at International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18, 04 Sep 2018, Torino, Italy (pp. 1252-1255). , Article ID 8502568.
Open this publication in new window or tab >>Service Level Agreements for Safe and Configurable Production Environments
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2018 (English)In: International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18, 2018, p. 1252-1255, article id 8502568Conference paper, Published paper (Refereed)
Abstract [en]

This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

National Category
Engineering and Technology Computer Systems
Identifiers
urn:nbn:se:mdh:diva-40884 (URN)10.1109/ETFA.2018.8502568 (DOI)000449334500177 ()2-s2.0-85057241752 (Scopus ID)9781538671085 (ISBN)
Conference
International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18, 04 Sep 2018, Torino, Italy
Projects
XPRES - Excellence in Production ResearchFuture factories in the Cloud
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2018-12-27Bibliographically approved
Ashjaei, S. M., Clegg, K., Corneo, L., Hawkins, R., Jaradat, O., Gulisano, V. M. & Nikolakopoulos, Y. (2018). Service Level Agreements for Safe and Configurable Production Environments. In: 2018 IEEE 23RD INTERNATIONAL CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA): . Paper presented at 23rd IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), SEP 04-07, 2018, Politecnico Torino, Torino, ITALY (pp. 1252-1255). IEEE
Open this publication in new window or tab >>Service Level Agreements for Safe and Configurable Production Environments
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2018 (English)In: 2018 IEEE 23RD INTERNATIONAL CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA), IEEE , 2018, p. 1252-1255Conference paper, Published paper (Refereed)
Abstract [en]

This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE International Conference on Emerging Technologies and Factory Automation-ETFA, ISSN 1946-0740
National Category
Computer Systems Other Engineering and Technologies not elsewhere specified Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:mdh:diva-41381 (URN)000449334500177 ()978-1-5386-7108-5 (ISBN)
Conference
23rd IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), SEP 04-07, 2018, Politecnico Torino, Torino, ITALY
Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-18
Jaradat, O. & Punnekkat, S. (2018). Using Safety Contracts to Verify Design Assumptions During Runtime. In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Volume 10873: . Paper presented at 23rd International Conference on Reliable Software Technologies, Ada-Europe 2018, 18-22 June 2018, Lisbon, Portugal (pp. 3-18).
Open this publication in new window or tab >>Using Safety Contracts to Verify Design Assumptions During Runtime
2018 (English)In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Volume 10873, 2018, p. 3-18Conference paper, Published paper (Refereed)
Abstract [en]

A safety case comprises evidence and argument justifying how each item of evidence supports claims about safety assurance. Supporting claims by untrustworthy or inappropriate evidence can lead to a false assurance regarding the safe performance of a system. Having sufficient confidence in safety evidence is essential to avoid any unanticipated surprise during operational phase. Sometimes, however, it is impractical to wait for high quality evidence from a system’s operational life, where developers have no choice but to rely on evidence with some uncertainty (e.g., using a generic failure rate measure from a handbook to support a claim about the reliability of a component). Runtime monitoring can reveal insightful information, which can help to verify whether the preliminary confidence was over- or underestimated. In this paper, we propose a technique which uses runtime monitoring in a novel way to detect the divergence between the failure rates (which were used in the safety analyses) and the observed failure rates in the operational life. The technique utilises safety contracts to provide prescriptive data for what should be monitored, and what parts of the safety argument should be revisited to maintain system safety when a divergence is detected. We demonstrate the technique in the context of Automated Guided Vehicles (AGVs).

Series
Lecture Notes in Computer Science, ISSN 0302-9743 ; 10873
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-38957 (URN)10.1007/978-3-319-92432-8_1 (DOI)000465823000001 ()2-s2.0-85049008966 (Scopus ID)9783319924311 (ISBN)
Conference
23rd International Conference on Reliable Software Technologies, Ada-Europe 2018, 18-22 June 2018, Lisbon, Portugal
Projects
SafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-05-16Bibliographically approved
Jaradat, O., Sljivo, I., Habli, I. & Hawkins, R. (2017). Challenges of Safety Assurance for Industry 4.0. In: European Dependable Computing Conference EDCC'17: . Paper presented at European Dependable Computing Conference EDCC'17, 04 Sep 2017, Geneva, Switzerland (pp. 103-106). Geneva, Switzerland: IEEE Computer Society
Open this publication in new window or tab >>Challenges of Safety Assurance for Industry 4.0
2017 (English)In: European Dependable Computing Conference EDCC'17, Geneva, Switzerland: IEEE Computer Society , 2017, p. 103-106Conference paper, Published paper (Refereed)
Abstract [en]

The Internet-of-Things (IoT) has enabled Industry 4.0 as a new manufacturing paradigm. The envisioned future of Industry 4.0 and Smart Factories is to be highly configurable and composed mainly of the 'things' that are expected to come with some, often partial, assurance guarantees. However, many factories are categorised as safety-critical, e.g. due to the use of heavy machinery or hazardous substances. As such, some of the guarantees provided by the 'things', e.g. related to performance and availability, are deemed as necessary in order to ensure the safety of the manufacturing processes and the resulting products. In this paper, we explore key safety challenges posed by Industry 4.0 and identify the characteristics that its safety assurance should exhibit. We propose a set of safety assurance responsibilities, e.g. system integrators, cloud service providers and `things' suppliers. Finally, we reflect on the desirable modularity of such a safety assurance approach as a basis for cooperative, on-demand and continuous reasoning for Industry 4.0 architectures and services.

Place, publisher, year, edition, pages
Geneva, Switzerland: IEEE Computer Society, 2017
Keywords
IoT, Cloud computing, Safety cases, Safety, Industry 4.0
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37027 (URN)10.1109/EDCC.2017.21 (DOI)000419858700018 ()2-s2.0-85041224275 (Scopus ID)978-1-5386-0602-5 (ISBN)
Conference
European Dependable Computing Conference EDCC'17, 04 Sep 2017, Geneva, Switzerland
Projects
Future factories in the Cloud
Available from: 2017-11-20 Created: 2017-11-20 Last updated: 2018-02-15Bibliographically approved
Girs, S., Sljivo, I. & Jaradat, O. (2017). Contract-Based Assurance for Wireless Cooperative Functions of Vehicular Systems. In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY: . Paper presented at 43rd Annual Conference of the IEEE Industrial Electronics Society IECON 2017, 30 Oct 2017, Beijing, China (pp. 8391-8396).
Open this publication in new window or tab >>Contract-Based Assurance for Wireless Cooperative Functions of Vehicular Systems
2017 (English)In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2017, p. 8391-8396Conference paper, Published paper (Refereed)
Abstract [en]

Cooperation of vehicular systems is the stepping stone towards both road and indoor smart transportation systems. It aims at increasing transportation efficiency and safety compared to the stand-alone vehicular systems. The usage of wireless communication as the foundation of such safety-critical cooperation needs to be embraced with all its benefits and flaws compared to the wired communication. The cooperative functions need to be designed to adapt to the varying reliability of the wireless communication channels such that both the stand-alone vehicles as well as the smart transportation system formed by their cooperation are deemed sufficiently safe. In this paper we build upon a contract-based runtime monitoring architecture and propose a methodology for assuring adaptive behaviour of transportation with respect to the wireless communication channel failures. More specifically, we elaborate how safety analysis of the interaction of the wirelessly connected vehicles can be used as the basis for derivation of the adaptive modes and the corresponding contracts. Furthermore, we discuss how such contracts can be used as the basis for assurance of the adaptive wireless cooperation. We illustrate the proposed methodology on a smart transportation system of a factory.

Series
IEEE Industrial Electronics Society, ISSN 1553-572X
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37330 (URN)000427164808041 ()2-s2.0-85046657321 (Scopus ID)978-1-5386-1127-2 (ISBN)
Conference
43rd Annual Conference of the IEEE Industrial Electronics Society IECON 2017, 30 Oct 2017, Beijing, China
Projects
Future factories in the CloudSafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2019-04-17Bibliographically approved
Jaradat, O. & Bate, I. (2017). Using Safety Contracts to Guide the Maintenance of Systems and Safety Cases. In: European Dependable Computing Conference EDCC'17: . Paper presented at European Dependable Computing Conference EDCC'17, 04 Sep 2017, Geneva, Switzerland (pp. 95-102).
Open this publication in new window or tab >>Using Safety Contracts to Guide the Maintenance of Systems and Safety Cases
2017 (English)In: European Dependable Computing Conference EDCC'17, 2017, p. 95-102Conference paper, Published paper (Refereed)
Abstract [en]

Changes to safety-critical systems are inevitable and can impact the safety confidence about a system as their effects can refute articulated claims about safety or challenge the supporting evidence on which this confidence relies. In order to maintain the safety confidence under changes, system developers need to re-analyse and re-verify the system to generate new valid items of evidence. Identifying the effects of a particular change is a crucial step in any change management process as it enables system developers to estimate the required maintenance effort and reduce the cost by avoiding wider analyses and verification than strictly necessary. This paper presents a sensitivity analysis-based technique which aims at measuring the ability of a system to contain a change (i.e., robustness) without the need to make a major re-design. The proposed technique exploits the safety margins in the budgeted failure probabilities of events in a probabilistic fault-tree analysis to compensate for unaccounted deficits or changes due to maintenance. The technique utilises safety contracts to provide prescriptive data for what is needed to be revisited and verified to maintain system safety when changes happen. We demonstrate the technique on an aircraft wheel braking system.

National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37017 (URN)10.1109/EDCC.2017.20 (DOI)000419858700017 ()2-s2.0-85041210865 (Scopus ID)978-1-5386-0602-5 (ISBN)
Conference
European Dependable Computing Conference EDCC'17, 04 Sep 2017, Geneva, Switzerland
Projects
SYNOPSIS - Safety Analysis for Predictable Software Intensive SystemsFuture factories in the CloudSafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2017-11-27 Created: 2017-11-27 Last updated: 2019-04-18Bibliographically approved
Jaradat, O. & Bate, I. (2017). Using Safety Contracts to Guide the Maintenance of Systems and Safety Cases: An Example. Västerås, Sweden: Mälardalen Real-Time Research Centre, Mälardalen University
Open this publication in new window or tab >>Using Safety Contracts to Guide the Maintenance of Systems and Safety Cases: An Example
2017 (English)Report (Other academic)
Abstract [en]

Changes to safety critical systems are inevitable and can impact the safety confidence about a system as their effects can refute articulated claims about safety or challenge the supporting evidence on which this confidence relies. In order to maintain the safety confidence due to changes, system developers need to re-analyse and re-verify the system to generate new valid items of evidence. Moreover, identifying the effects of a particular change is a crucial step in any change management process as it enables system developers to estimate the required maintenance effort and reduce the cost by avoiding wider analyses and verification than strictly necessary. This paper presents a sensitivity analysis-based technique which aims at measuring the ability of a system to contain a change (i.e., robustness) without the need to make a major re-design. The technique exploits the safety margins in the assigned failure probabilities to the events of a probabilistic fault-tree analysis to compensate some potential deficits in the overall failure probability budget due to changes. The technique also utilises safety contracts to provide prescriptive data for what is needed to be revisited and verified to maintain system safety when changes happen. We demonstrate the technique on a realistic safety critical system.

Place, publisher, year, edition, pages
Västerås, Sweden: Mälardalen Real-Time Research Centre, Mälardalen University, 2017
Series
MRTC Reports, ISSN 1404-3041
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-35495 (URN)MDH-MRTC-317/2017-1-SE (ISRN)
Projects
SYNOPSIS - Safety Analysis for Predictable Software Intensive SystemsFuture factories in the CloudSafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2019-04-16Bibliographically approved
Jaradat, O. & Bate, I. (2016). Systematic Maintenance of Safety Cases to Reduce Risk. In: Lecture Notes in Computer Science, vol. 9923: . Paper presented at 4th International Workshop on Assurance Cases for Software-intensive Systems ASSURE2016, 20-23 Sep 2016, Trondheim, Norway (pp. 17-29).
Open this publication in new window or tab >>Systematic Maintenance of Safety Cases to Reduce Risk
2016 (English)In: Lecture Notes in Computer Science, vol. 9923, 2016, p. 17-29Conference paper, Published paper (Refereed)
Abstract [en]

The development of safety cases has become common practice in many safety critical system domains. Safety cases are costly since they need a significant amount of time and efforts to be produced. More- over, safety critical systems are expected to operate for a long period of time and constantly subject to changes during both development and operational phases. Hence, safety cases are built as living documents that should always be maintained to justify the safety status of the associated system and evolve as these system evolve. However, safety cases document highly interdependent elements (e.g., safety goals, evidence, assumptions, etc.) and even seemingly minor changes may have a major impact on them, and thus dramatically increase their cost. In this paper, we identify and discuss some challenges in the maintenance of safety cases. We also present two techniques that utilise safety contracts to facilitate the maintenance of safety cases, we discuss the roles of these techniques in coping with some of the identified maintenance challenges, and we finally discuss potential limitations and suggest some solutions.

Series
Lecture Notes in Computer Science, ISSN 0302-9743 ; 9923
Keywords
Safety CaseSafety ArgumentMaintenanceFTASensitivity AnalysisSafety ContractsImpact Analysis
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-32882 (URN)10.1007/978-3-319-45480-1_2 (DOI)000387734000003 ()2-s2.0-84988350318 (Scopus ID)9783319454795 (ISBN)
Conference
4th International Workshop on Assurance Cases for Software-intensive Systems ASSURE2016, 20-23 Sep 2016, Trondheim, Norway
Projects
SYNOPSIS - Safety Analysis for Predictable Software Intensive SystemsFuture factories in the CloudSafeCOP - Safe Cooperating Cyber-Physical Systems using Wireless Communication
Funder
EU, Horizon 2020, 692529 Vinnova
Available from: 2016-08-26 Created: 2016-08-24 Last updated: 2019-04-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9347-1949

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