Jakob Axelsson

This paper describes the step-by-step processes towards the formalization of a core ontology for missions and capabilities in systems of systems, and the development of a specific system of systems domain ontology from the formalized ontology. The study traces the ontology development process through the SABIOx methodology’s requirements, setup, capture, design, and implementation phases. In this process, we demonstrate the core ontology’s usability and reusability. Usability refers to the ontology’s adequacy for specific use as a reference point for SoS knowledge exploration for development and operational purposes, and reusability refers to the ontology’s adequacy for several uses, such as facilitating the understanding of different domain-specific systems of systems. This demonstration is done in three steps: formalization of the core ontology, exploration of the usefulness of this formalization, and development of a domain ontology from the core ontology. These result in: the incorporation of systematic ontology development processes; the application of ontology tools for machine readability; coherence and consistency checking of the ontology artifact; querying support for the ontology knowledge base; and testing of the core knowledge with a domain-specific system of systems. An alignment of these aspects provides different points of view of how a system of systems can be formulated, how the concepts collectively describe the development of an SoS emergent behavior, and how the ontology knowledge base can be explored to support decision frameworks guiding a system of systems.

This paper describes the step-by-step processes towards the formalization of a core ontology for missions and capabilities in a system of systems, and the development of a specific SoS domain ontology from the formalized ontology. The study adopts the SABIOx methodology to trace the different aspects of the ontology development process from requirements, setup, capture, design, and implementation phases. This study also demonstrates the core ontology’s usability and reusability. Usability refers to its adequacy for specific use as a reference point for SoS knowledge exploration for development and operational purposes. Reusability refers to adequacy for several uses, such as facilitating the understanding of different domain-specific systems of systems. This is done in three steps: formalization of the core ontology, exploration of the usefulness of this formalization, and development of a domain ontology from the core ontology. These result in: the application of ontology tools to demonstrate the machine readability, inferences, and possibilities to querying the ontology knowledge base; the incorporation of systematic ontology development processes; and testing of the core knowledge with a domain prompt. An alignment of these aspects provides different points of view of how an SoS can be formulated, how the concepts collectively describe the development of an SoS emergent behavior, and how the ontology knowledge base can be explored to support decision frameworks guiding an SoS.

The systems-of-systems (SoS) field has, over the last few decades, progressed from initial problem awareness, through conceptualization and characterization, into maturation and codification in engineering standards. This has resulted in knowledge that helps in resolving practical complex systems problems. However, research challenges remain that appear difficult to handle within the current practice. This paper looks at the development of SoS engineering through the lens of Kuhn's theory of scientific revolutions. It summarizes some of the key features of the current SoS engineering paradigm and identifies a number of anomalies in it. Based on these anomalies, a new SoS paradigm is suggested, which builds extensively on systems theory, cybernetics, and complexity theory. It views an SoS as a sociotechnical situation, and its elements as agents with different world models. The agents interact in dynamic heterarchical networks, and the SoS is engineered from the inside by its participating agents. The paper thus contributes by pointing out a potential direction in which the field could develop to provide enhanced methods suitable for a broader range of complex SoS applications.

The System Theoretic Accident Model and Processes (STAMP) considers safety as a dynamic problem by focusing on interactions among system components rather than on component failure. However, analyzing complex system risks with STAMP can be challenging due to manual processes. Therefore, software tools supporting STAMP analysis have been developed. An evaluation of five tools (ASTAH, STPA, Capella, XSTAMPP, STPA Master Lite, and Visio Pro) was conducted, focusing on systems of systems (SoS) risk analysis. While all tools demonstrated compliance with the STAMP risk analysis procedure, with some tools offering additional features, a shortcoming in scalability limits the support for risk analysis of SoS. This makes risk analysis with the available STAMP tools challenging for SoS. Recommended enhancements include mechanisms to address SoS characteristics, scalability, collaboration, and improved usability. The study contributes to research on SoS risk analysis and provides direction for advancement in risk analysis tool support.

Systems-of-systems are often characterized as systems where the constituent parts have some independence from the whole. Recent research has aimed at clarifying in more detail what this independence means. It has shown that independence requires the constituent systems to be agents that observe the system-of-systems from within and construct internal models of it as a basis for decisions. This view on observers as parts of the system-of-systems parallels development in the field of second-order cybernetics several decades ago, yet the connection between that field and systems-of-systems has not been explored previously. This paper, therefore, summarizes key concepts from second-order cybernetics, including the subtopic autopoiesis. It then discusses what the implications are on systems-of-systems engineering through the identification of 17 concerns. These concerns relate to the physical topology, behavior, and control of the system-of-systems. This paper shows how these concerns directly relate to the theoretical concepts of second-order cybernetics and autopoiesis, and thereby, opens the door to further exploitation of this theoretical foundation.

The concept of a mission is important to system design and development, especially in system of systems (SoS) engineering. However, the diverse usage of the term ’mission’ across disciplines often results in ambiguity regarding its role in practical applications in mission-centric engineering tasks. Clearly defined and precisely represented missions improve communication among stakeholders and help bridge interdisciplinary gaps. This study aims to investigate and analyze the state of the art for mission conceptualizations and representations and proposes a unified mission ontology (UMO) that improves semantic interoperability across various domains. To achieve this goal, we conducted a systematic literature review (SLR) to examine how missions are conceptualized and represented, analyzed the findings to obtain insight about cross-domain concepts related to missions, and developed a UMO that can be adapted to domain specific applications. The UMO facilitates semantic interoperability across domains through a high-level abstraction of shared concepts. To validate the comprehensiveness and adaptability of the UMO, we conducted coverage analysis using semantic similarity estimates to assess the equivalence of ontological concepts. This evaluation quantified the extent to which concepts from various domain-specific ontologies, including the mission engineering guideline, align with those in the UMO.

The concept of a mission is fundamental to system design and development, especially in system of systems (SoS) engineering. However, the diverse usage of the term 'mission' across disciplines, coupled with the absence of universally accepted definitions, often results in ambiguity regarding its core meaning and practical application in mission-centric engineering tasks. Clearly defined and precisely represented missions are essential for improving communication among stakeholders and bridging interdisciplinary gaps. This study aims to develop a unified mission ontology that promotes clarity and improves interoperability across various domains. To achieve this goal, we conducted a systematic literature review (SLR) to examine how missions are conceptualized and represented, followed by a thorough analysis of the findings. Based on the analysis results, we propose a unified mission ontology that can be tailored for domain-specific applications, promoting interoperability across domains through a high-level abstraction of shared concepts. To validate the comprehensiveness and adaptability of the proposed unified mission ontology, we conducted a coverage analysis using semantic similarity estimates to assess the equivalence of ontological concepts. This evaluation quantified the extent to which concepts from various domain-specific ontologies, including the mission engineering guideline, align with those in the proposed unified mission ontology.

In most systems-of-systems (SoS) and ecosystems, peer-to-peer relations are insufficient to provide the desired emergent behavior, but the support of mediators is necessary. Mediators are elements that facilitate the collaboration between the constituents of the SoS or ecosystem, without having a role outside it. The topic has previously been studied in the SoS field, mainly from a software engineering perspective, and separately also in research on software, business, and innovation ecosystems. This paper presents a systematic literature review on mediators across scholarly work in SoS as well as ecosystems. It identifies mediator functionality and implementation concerns, and discusses alternative terminology. Based on findings from the literature, a suggestion for an improved conceptualization is presented, which also includes the information, processing and interactions involved in the mediation.

This paper describes the Architecture Life Cycle Effect Analysis (ALCEA) method, a structured method for evaluating proposed new architectures for software-intensive systems. The method evaluates a proposed architecture by quantifying its effect on the performance of system life-cycle phases. The method is instantiated by identifying (i) the relevant life-cycle phases of the system under investigation and (ii) a set of evaluation functions that capture, in terms of basic factors, the effect of different architectural decisions on key life-cycle performance attributes, such as revenue, operating resources, and investments. The method results in a transparent cost and revenue structure, documented in a tabular form, based on quantifiable factors from the developing organization. The results of the method can be used directly as part of a business case, and their robustness can be estimated by sensitivity analysis. The ALCEA method is designed for system-level architectural analysis, covering both software and hardware aspects. In this paper, we introduce the ALCEA method and provide a detailed example of how to apply it in the evolution of embedded systems. Moreover, we share early experiences of using the method in large-scale industrial settings.