This paper develops Brinch-Hansen's concept of a monitor as a method of structuring an operating system. It introduces a form of synchronization, describes a possible method of implementation in terms of semaphores and gives a suitable proof rule. Illustrative examples include a single resource scheduler, a bounded buffer, an alarm clock, a buffer pool, a disk head optimizer, and a version of the problem of readers and writers.

Monitors: An Operating System Structuring Concept

Ontology-based systems engineering: A state-of-the-art review

There are seven different systems that must be acknowledged and understood by those who purport to do systems engineering. The main system to be engineered is the Intervention System that will be designed to solve a real or perceived problem. The Intervention System will be placed in a Context System and must be developed and deployed using a Realization System. The Intervention, when installed in the Context, becomes the Deployed System which is often different in substantial ways from the original intent of the Intervention. This Deployed System will interact with Collaborating Systems to accomplish its own functions. A Sustainment System provides services and materials to keep the Deployed System operational. Finally, there are one or more Competing Systems that may also solve the original problem and will compete for resources with your Deployed System. All seven systems must be properly reckoned with when engineering a system.

3.1.2 The Seven Samurai of Systems Engineering: Dealing with the Complexity of 7 Interrelated Systems

Human factors and ergonomics needs to ensure that its methods are available, usable and used in practice. The majority of our methods tend to be developed by researchers situated in academic institutions, and published in scientific journals, books and conference proceedings. The intended or assumed end-users of HF/E methods, on the other hand, are often practitioners embedded in consultancies, producers, manufacturers, service providers, government departments and so on. The difference in context contributes to a research-practice gap, resulting in a number of issues such as reliance on old methods, low uptake of new methods and application problems. This commentary article outlines three key constraints from our own experience as practitioners and researchers – as tool users and developers – that affect the application of methods in practice. We suggest several implications and ways to improve the availability and actual use of HF/E methods.

https://www.tandfonline.com/doi/pdf/10.1080/1463922X.2016.1155240

Human factors and ergonomics methods in practice: three fundamental constraints

The construction industry uses more resources and produces more waste than any other industrial sector; sustainable development depends on the reduction of both, while providing for a growing global population. The reuse of existing building components could support this goal. However, it is difficult to reclaim components from demolition, and materials remain cheap compared with labour, so new approaches are needed for reuse to be implemented beyond niche projects. This study therefore reviews waste interventions. Multiple case studies, spanning new builds and refurbishment, were undertaken to examine systemic mechanisms that lead to components being discarded. Evidence from fieldwork observations, waste documentation, and interviews indicates that the generators of unwanted components effectively decide their fate, and a failure to identify components in advance, uncertainty over usefulness, the perception of cost and programme risk in reclamation, and the preferential order of the waste hierarchy mean that the decision to discard to waste management goes unchallenged. A triage process is proposed to capture timely information about existing building components to be discarded, make this information visible to a wide community, and determine usefulness by focusing creativity already present in the industry on an exhaustive examination of component reusability and upcyclability.

From Waste Management to Component Management in the Construction Industry

Over the past decades, a common definition of the term system has eluded researchers and practitioners alike. We reviewed over 100 current and historical definitions of system in an effort to understand perspectives and to propose the most comprehensive definition of this term. There is much common ground in different families of definition of system, but there are also important and significant differences. Some stem from different belief systems and worldviews, while others are due to a pragmatic desire to establish a clear definition for system within a particular community, disregarding wider considerations. In either case, it limits the effectiveness of various system communities' efforts to communicate, collaborate, and learn from the experience of other communities. We discovered that by considering a wide typology of systems, Bertalanffy's General Systems Theory provides a basis for a general, self-consistent sensible framework, capable of accommodating and showing the relationships amongst the variety of different definitions of and belief systems pertaining to system. Emergence, the appearance of a new phenomenon or capability as a result of relation or interaction between objects, is key in differentiating between objects that are systems and those that are not. Hence we propose a family of definitions, related by the common theme of emergence, which is in line with both the realist and constructivist worldviews, and covers real and conceptual systems. We believe this better reflects the current scope of systems engineering and is required to support the aspirations expressed in INCOSE SE Vision 2025.

Defining “System”: a Comprehensive Approach

The definition and characteristics of system have eluded humans for a very long time, as different people refer to the concept of system in various ways. A set of surveys conducted by us revealed seven distinct worldviews on system. We describe the surveys, analyze their results, and comment on differences between the responses. Based on the outcomes, we offer a comprehensive definition of system that can be accepted by the various worldview holders as an arrangement of parts or elements that together exhibit behavior or meaning that the individual constituents do not . Further, we present a compiled list of systemness characteristics—features that different worldview holders expect any system to exhibit. Then we present and describe the different worldviews on system, compare them with previous system definitions, and map them to five system domains. We conclude that the various system worldviews offer useful perspectives for systems engineers, who should have the flexibility to accept the fact that different worldviews may be appropriate for different situations and be ready to adopt them as necessary.

System Definition, System Worldviews, and Systemness Characteristics

The System Definition Survey issued to INCOSE Fellows in December 2016 revealed at least five radically distinct worldviews on Systems within a relatively small, but moderately representative, part of the INCOSE community. We describe and analyse the survey results, and comment on differences between the responses from the Fellows and the responses to a similar survey issued to the System Science Working Group a month later. Then we discuss how the different worldviews on “system” revealed by the surveys map onto different areas of the set of system definitions described in a previous paper. We conclude that all the worldviews identified offer useful perspectives for systems engineering, and that Systems Engineers need the flexibility to adopt different worldviews for different situations, or at least to act “as if” different worldviews are true in different situations.

What do we mean by “system”? – System Beliefs and Worldviews in the INCOSE Community

The National Oceanic and Atmospheric Administration (NOAA) in the United States has a very broad charter that includes making “observations” of environmental phenomena worldwide. These observing systems are used to provide accurate and timely information to various stakeholders who depend on this information to make critical decisions about farming, construction, fishing, military operations, traffic safety, and so on. This paper describes a project to develop the NOAA Observing System Architecture to assist NOAA in formulating its strategic plans and invest its funding more effectively. We used “knowledge modeling” as the basic approach to capture information about the systems and other entities associated with the architecture. We are using the Metis enterprise architecture tool along with DOORS for requirements, NOAA Forge for team collaboration, and ArcIMS for geospatial data visualization.

James N Martin

Papers

3.1.2 The Seven Samurai of Systems Engineering: Dealing with the Complexity of 7 Interrelated Systems

Defining “System”: a Comprehensive Approach

System Definition, System Worldviews, and Systemness Characteristics

What do we mean by “system”? – System Beliefs and Worldviews in the INCOSE Community

6.4.1 On the Use of Knowledge Modeling Tools and Techniques to Characterize the NOAA Observing System Architecture