Open AccessFeature PaperArticle
Reflections on Teaching System Dynamics Modeling to Secondary School Students for over 20 Years
Systems 2018, 6(2), 12; doi:10.3390/systems6020012 -
Abstract
This paper contains the description of a successful system dynamics (SD) modeling approach used for almost a quarter-century in secondary schools, both in algebra classes and in a year-long SD modeling course. Secondary school students have demonstrated an ability to build original models
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This paper contains the description of a successful system dynamics (SD) modeling approach used for almost a quarter-century in secondary schools, both in algebra classes and in a year-long SD modeling course. Secondary school students have demonstrated an ability to build original models from the news, write technical papers explaining their models, and present a newfound understanding of dynamic feedback behavior to an audience. The educational learning theory and instructional methods used for both the algebra and modeling courses are detailed, with examples. Successful student SD modeling experiences suggest the SD approach can expand the sophistication of topics that secondary school students can understand. Full article
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Open AccessArticle
Online Academic Networks as Knowledge Brokers: The Mediating Role of Organizational Support
Systems 2018, 6(2), 11; doi:10.3390/systems6020011 -
Abstract
Placing online academic networks in the framework of social, cultural and institutional “deterritorialization,” the current paper aims at investigating the functionality of these new forms of transnational and trans-organizational aggregations as knowledge brokers. The emphasis is laid on the influence of human collective
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Placing online academic networks in the framework of social, cultural and institutional “deterritorialization,” the current paper aims at investigating the functionality of these new forms of transnational and trans-organizational aggregations as knowledge brokers. The emphasis is laid on the influence of human collective intelligence and consistent knowledge flows on research innovation, considering the role of organizational support within higher education systems. In this respect, the research relied on a questionnaire-based survey with 140 academics from European emerging countries, the data collected being processed via a partial least squares structural equation modelling technique. Evidence was brought that, as knowledge brokers, online academic networks are systems aimed to support the access to human collective intelligence and consistent knowledge flows which exert a positive influence on research innovation, both directly and indirectly, by means of formal and informal organizational support. As facilitators of collaborative environments for individuals with specialized knowledge, competence, expertise and experience, online academic networks have set themselves up as an agora for academics worldwide and as an outlet for their acumen and literacy. Full article
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Open AccessArticle
Efficient and Equitable Climate Change Policies
Systems 2018, 6(2), 10; doi:10.3390/systems6020010 -
Abstract
This report describes the Integrated Assessment Model TIAM-MACRO, which is a Ramsey-type macroeconomic growth model linked with a technology-rich engineering model of the energy-system and with a stylized sub-model of climate change. TIAM-MACRO contributes to coherent and consistent policy analyses at both the
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This report describes the Integrated Assessment Model TIAM-MACRO, which is a Ramsey-type macroeconomic growth model linked with a technology-rich engineering model of the energy-system and with a stylized sub-model of climate change. TIAM-MACRO contributes to coherent and consistent policy analyses at both the world and regional level and correlates demand for energy services to macro-economic developments across regions and time until the end of the 21st century. With the help of this model, two contrasting scenarios are defined related to the reference development (BASE) case and the 2 °C (2DS) case that follow long-term policies on climatic change mitigation in the spirit of the Paris agreement. Finally, we define ex-post market and non-market damages together with the damages related to Local Atmospheric Pollutants (LAP). The stringency of the 2DS case requires the complete restructuring of the energy and transport systems to be relying on carbon-free technologies and fuels together with technologies of negative emissions, at high costs. The study concludes that carbon policies not only consist of an insurance against the risk of climate change but also improve the ambient air quality, as they have secondary benefits that compensate for part of the cost of carbon control. However, the stringency of the 2DS case is so demanding that the cost of climate policies is above benefits. Full article
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Open AccessReview
Floodplains and Complex Adaptive Systems—Perspectives on Connecting the Dots in Flood Risk Assessment with Coupled Component Models
Systems 2018, 6(2), 9; doi:10.3390/systems6020009 -
Abstract
Floodplains, as seen from the flood risk management perspective, are composed of co-evolving natural and human systems. Both flood processes (that is, the hazard) and the values at risk (that is, settlements and infrastructure built in hazardous areas) are dynamically changing over time
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Floodplains, as seen from the flood risk management perspective, are composed of co-evolving natural and human systems. Both flood processes (that is, the hazard) and the values at risk (that is, settlements and infrastructure built in hazardous areas) are dynamically changing over time and influence each other. These changes influence future risk pathways. The co-evolution of all of these drivers for changes in flood risk could lead to emergent behavior. Hence, complexity theory and systems science can provide a sound theoretical framework for flood risk management in the 21st century. This review aims at providing an entry point for modelers in flood risk research to consider floodplains as complex adaptive systems. For the systems science community, the actual problems and approaches in the flood risk research community are summarized. Finally, an outlook is given on potential future coupled component modeling approaches that aims at bringing together both disciplines. Full article
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Open AccessArticle
Adding Feedbacks and Non-Linearity to the Neoclassical Growth Model: A New Realm for System Dynamics Applications
Systems 2018, 6(2), 8; doi:10.3390/systems6020008 -
Abstract
Modelling of economic systems is traditionally associated with a mathematical formalism that has its drawbacks and limitations. This study applies system dynamics as a specific modelling technique that enables us to modify and elaborate existing economic models and improve them both from a
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Modelling of economic systems is traditionally associated with a mathematical formalism that has its drawbacks and limitations. This study applies system dynamics as a specific modelling technique that enables us to modify and elaborate existing economic models and improve them both from a theoretical perspective and for practical applications. More specifically, the Solow-Swan growth model is enriched by feedback and non-linearity based on its extension by the energy sector. The influence and role of renewable resources are considered in this enhancement. The developed model is tested in two different scenarios and utilizes sensitivity analysis as the primary tool. Acquired outcomes offer a new perspective on the economy–energy nexus based on real data and demonstrate that system dynamics can be successfully used as a modelling tool even in the theoretical economics as a traditional discipline. Full article
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Open AccessFeature PaperArticle
On the Architecture of Systemology and the Typology of Its Principles
Systems 2018, 6(1), 7; doi:10.3390/systems6010007 -
Abstract
Systems engineering is increasingly challenged by the rising complexity of projects undertaken, resulting in increases in costs, failure rates, and negative unintended consequences. This has resulted in calls for more scientific principles to underpin the methods of systems engineering. In this paper, it
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Systems engineering is increasingly challenged by the rising complexity of projects undertaken, resulting in increases in costs, failure rates, and negative unintended consequences. This has resulted in calls for more scientific principles to underpin the methods of systems engineering. In this paper, it is argued that our ability to improve systems Engineering’s methods depends on making the principles of systemology, of which systems engineering is a part, more diverse and more scientific. An architecture for systemology is introduced, which shows how the principles of systemology arise from interdependent processes spanning multiple disciplinary fields, and on this basis a typology is introduced, which can be used to classify systems principles and systems methods. This framework, consisting of an architecture and a typology, can be used to survey and classify the principles and methods currently in use in systemology, map vocabularies referring to them, identify key gaps, and expose opportunities for further development. It may, thus, serve as a tool for coordinating collaborative work towards advancing the scope and depth of systemology. Full article
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Open AccessArticle
Veterinary Telemedicine: A System Dynamics Case Study
Systems 2018, 6(1), 6; doi:10.3390/systems6010006 -
Abstract
Veterinary telemedicine has existed since the late 1990s. Various scholars have predicted its growth, others its decline. We constructed a system dynamics model of a veterinary telemedicine company providing services in one specialty in the industry. The model showed that severe shortages of
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Veterinary telemedicine has existed since the late 1990s. Various scholars have predicted its growth, others its decline. We constructed a system dynamics model of a veterinary telemedicine company providing services in one specialty in the industry. The model showed that severe shortages of specialists would limit growth in that, even with extensive marketing efforts. This limitation is likely to hold in other aspects of veterinary telemedicine. The paper concludes with recommendations for the company and the industry. Full article
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Open AccessEditorial
Overview and Insights from ‘Systems Education for a Sustainable Planet’
Systems 2018, 6(1), 5; doi:10.3390/systems6010005 -
Abstract
An announcement by Bosch and Cavana, in Systems, called for new papers to provide updated perspectives about and fresh insights into developments that influence ‘systems education for a sustainable planet’. This paper’s objective is to provide an overview of the 14 papers that
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An announcement by Bosch and Cavana, in Systems, called for new papers to provide updated perspectives about and fresh insights into developments that influence ‘systems education for a sustainable planet’. This paper’s objective is to provide an overview of the 14 papers that were published in the special issue, and present some insights and findings from their content. It does this by classifying the papers into five distinct themes, then analysing their content and the linkages between the themes. This process revealed that: (1) Specialised systems education at a tertiary level is predominantly at graduate level, using a diverse range of approaches; and (2) Delivering specialised systems education remains a challenge for programs that endeavour to provide an integrated and interdisciplinary learning experience. Barriers include current institutional structures and the need for students to be both big picture thinkers and detail-oriented technocrats; (3) Teaching systems approaches outside of specialised programs for students (both young and mature) help to expose systems thinking to a wider demographic; (4) The strong links that exist between systems approaches and sustainability goals are increasingly being recognised. Systems education can help transition towards a sustainable planet, as it helps people appreciate that individual actions are not isolated events but contribute to an interconnected system that determines both the well-being of humans and the planet. Full article
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Open AccessArticle
Rediscovering and Reviving Old Observations and Explanations of Metabolic Scaling in Living Systems
Systems 2018, 6(1), 4; doi:10.3390/systems6010004 -
Abstract
Why the rate of metabolism varies (scales) in regular, but diverse ways with body size is a perennial, incompletely resolved question in biology. In this article, I discuss several examples of the recent rediscovery and (or) revival of specific metabolic scaling relationships and
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Why the rate of metabolism varies (scales) in regular, but diverse ways with body size is a perennial, incompletely resolved question in biology. In this article, I discuss several examples of the recent rediscovery and (or) revival of specific metabolic scaling relationships and explanations for them previously published during the nearly 200-year history of allometric studies. I carry out this discussion in the context of the four major modal mechanisms highlighted by the contextual multimodal theory (CMT) that I published in this journal four years ago. These mechanisms include metabolically important processes and their effects that relate to surface area, resource transport, system (body) composition, and resource demand. In so doing, I show that no one mechanism can completely explain the broad diversity of metabolic scaling relationships that exists. Multi-mechanistic models are required, several of which I discuss. Successfully developing a truly general theory of biological scaling requires the consideration of multiple hypotheses, causal mechanisms and scaling relationships, and their integration in a context-dependent way. A full awareness of the rich history of allometric studies, an openness to multiple perspectives, and incisive experimental and comparative tests can help this important quest. Full article
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Open AccessConcept Paper
How to Disable Mortal Loops of Enterprise Resource Planning (ERP) Implementation: A System Dynamics Analysis
Systems 2018, 6(1), 3; doi:10.3390/systems6010003 -
Abstract
Successful Enterprise Resource Planning (ERP) implementation depends upon various factors known as critical success factors (CSFs). This study developed a system dynamics model of ERP implementation based on CSFs to discuss ERP implementation complexities, which identifies the effect of CSF interrelations on different
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Successful Enterprise Resource Planning (ERP) implementation depends upon various factors known as critical success factors (CSFs). This study developed a system dynamics model of ERP implementation based on CSFs to discuss ERP implementation complexities, which identifies the effect of CSF interrelations on different aspects of ERP project failure. Based on the model hypothesis, CSF interrelations include many causal loop dependencies. Some of these causal loops are called mortal loops, because they may cause the failure of risk reduction efforts to a more severe failure in effect of lack of system thinking on CSFs interrelations. This study discusses how system thinking works as a leverage point for overcoming ERP implementation challenges. Full article
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Open AccessArticle
Compositional Approach to Distributed System Behavior Modeling and Formal Validation of Infrastructure Operations with Finite State Automata: Application to Viewpoint-Driven Verification of Functionality in Waterways
Systems 2018, 6(1), 2; doi:10.3390/systems6010002 -
Abstract
Now that modern infrastructure systems are moving toward an increased use of automation in their day-to-day operations, there is an emerging need for new approaches to the formal analysis and validation of system functionality with respect to correctness of operations. This paper describes
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Now that modern infrastructure systems are moving toward an increased use of automation in their day-to-day operations, there is an emerging need for new approaches to the formal analysis and validation of system functionality with respect to correctness of operations. This paper describes a compositional approach to the multi-level behavior modeling and formal validation of large-scale distributed system operations with hierarchies and networks of finite state automata. To avoid the well-known state explosion problem, we develop a new procedure for viewpoint-action-process traceability, thereby allowing parts of a behavior model not relevant to a specific decision to be removed from consideration. Key features of the methodology are illustrated through the development of behavior models and validation procedures for polite conversation between two individuals, and lockset- and system-level concerns for ships traversing a large-scale waterway system. Full article
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Open AccessEditorial
Acknowledgement to Reviewers of Systems in 2017
Systems 2018, 6(1), 1; doi:10.3390/systems6010001 -
Abstract
Peer review is an essential part in the publication process, ensuring that Systems maintains high quality standards for its published papers. In 2017, a total of 53 papers were published in the journal.[...] Full article
Open AccessArticle
Using Agent-Based Modeling to Assess Liquidity Mismatch in Open-End Bond Funds
Systems 2017, 5(4), 54; doi:10.3390/systems5040054 -
Abstract
In this paper, we introduce a small-scale heterogeneous agent-based model of the US corporate bond market. The model includes a realistic micro-grounded ecology of investors that trade a set of bonds through dealers. Using the model, we simulate market dynamics that emerge from
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In this paper, we introduce a small-scale heterogeneous agent-based model of the US corporate bond market. The model includes a realistic micro-grounded ecology of investors that trade a set of bonds through dealers. Using the model, we simulate market dynamics that emerge from agent behaviors in response to basic exogenous factors (such as interest rate shocks) and the introduction of regulatory policies and constraints. A first experiment focuses on the liquidity transformation provided by mutual funds and investigates the conditions under which redemption-driven bond sales may trigger market instability. We simulate the effects of increasing mutual fund market shares in the presence of market-wide repricing of risk (in the form of a 100 basis point increase in the expected returns). The simulations highlight robust-yet-fragile aspects of the growing liquidity transformation provided by mutual funds, with an inflection point beyond which redemption-driven negative feedback loops trigger market instability. Full article
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Open AccessArticle
A Conceptual Design of Spatio-Temporal Agent-Based Model for Volcanic Evacuation
Systems 2017, 5(4), 53; doi:10.3390/systems5040053 -
Abstract
The understanding of evacuation processes is important for improving the effectiveness of evacuation plans in the event of volcanic disasters. In terms of social processes, the enactment of evacuations in volcanic crises depends on the variability of individual/household responses. This variability of population
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The understanding of evacuation processes is important for improving the effectiveness of evacuation plans in the event of volcanic disasters. In terms of social processes, the enactment of evacuations in volcanic crises depends on the variability of individual/household responses. This variability of population response is related to the uncertainty and unpredictability of the hazard characteristics of volcanoes—specifically, the exact moment at which the eruption occurs (temporal), the magnitude of the eruption and which locations are impacted (spatial). In order to provide enhanced evacuation planning, it is important to recognise the potential problems that emerge during evacuation processes due to such variability. Evacuation simulations are one approach to understanding these processes. However, experimenting with volcanic evacuations in the real world is risky and challenging, and so an agent-based model is proposed to simulate volcanic evacuation. This paper highlights the literature gap for this topic and provides the conceptual design for a simulation using an agent-based model. As an implementation, an initial evacuation model is presented for Mount Merapi in Indonesia, together with potential applications of the model for supporting volcanic evacuation management, discussion of the initial outcomes and suggestions for future work. Full article
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Open AccessArticle
An Integral Model to Provide Reactive and Proactive Services in an Academic CSIRT Based on Business Intelligence
Systems 2017, 5(4), 52; doi:10.3390/systems5040052 -
Abstract
Cyber-attacks have increased in severity and complexity. That requires, that the CERT/CSIRT research and develops new security tools. Therefore, our study focuses on the design of an integral model based on Business Intelligence (BI), which provides reactive and proactive services in a CSIRT,
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Cyber-attacks have increased in severity and complexity. That requires, that the CERT/CSIRT research and develops new security tools. Therefore, our study focuses on the design of an integral model based on Business Intelligence (BI), which provides reactive and proactive services in a CSIRT, in order to alert and reduce any suspicious or malicious activity on information systems and data networks. To achieve this purpose, a solution has been assembled, that generates information stores, being compiled from a continuous network transmission of several internal and external sources of an organization. However, it contemplates a data warehouse, which is focused like a correlator of logs, being formed by the information of feeds with diverse formats. Furthermore, it analyzed attack detection and port scanning, obtained from sensors such as Snort and Passive Vulnerability Scanner, which are stored in a database, where the logs have been generated by the systems. With such inputs, we designed and implemented BI systems using the phases of the Ralph Kimball methodology, ETL and OLAP processes. In addition, a software application has been implemented using the SCRUM methodology, which allowed to link the obtained logs to the BI system for visualization in dynamic dashboards, with the purpose of generating early alerts and constructing complex queries using the user interface through objects structures. The results demonstrate, that this solution has generated early warnings based on the level of criticality and level of sensitivity of malware and vulnerabilities as well as monitoring efficiency, increasing the level of security of member institutions. Full article
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Open AccessArticle
Social Systems: Resources and Strategies
Systems 2017, 5(4), 51; doi:10.3390/systems5040051 -
Abstract
This theoretical article reviews the model describing processes in social systems based on the analysis of their resource base. Application of the system theory can help to explain why some systems are aimed at prevention of type I errors, while others seek to
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This theoretical article reviews the model describing processes in social systems based on the analysis of their resource base. Application of the system theory can help to explain why some systems are aimed at prevention of type I errors, while others seek to decrease the quantity of type II errors. Such differences are manifested in investment of resources either into deep interaction or into wide coverage. Some examples of such strategies in economic, market and production systems are provided in the article. The article introduces some provisions of the system theory in the context of the resource flows. The main indicators that are considered in this article are the characteristics of the sources of the exchanging flows of resources. Their relative frequency and quality are investigated; on the basis of which the most effective strategy of the system is derived; as a mechanism for redistribution of resources. The rigor of the system’s strategy depends on the magnitude of the difference in characteristics. It is explained how exactly it influences the exchange processes, that in reality systems do not interact simultaneously and one of the opposite resource flows is always delayed. It is shown how the system strategy depends on the risks linked with interactions. Also, there are grounds for the need to accumulate resources, including in the situation of their surplus. The model helps also explain shift of economic centers throughout history. Additionally, there is an analogy between systems strategies and the competitive strategies described by M. Porter and outsourcing versus integration. Full article
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Open AccessFeature PaperArticle
The Complementary Perspective of System of Systems in Collaboration, Integration, and Logistics: A Value-Chain Based Paradigm of Supply Chain Management
Systems 2017, 5(4), 50; doi:10.3390/systems5040050 -
Abstract
The importance and complexity of the problems associated with coordinating multiple organizations to configure value propositions for customers has drawn the attention of multiple disciplines. In an effort to clarify and consolidate terms, this conceptual research examines both supply chain management (SCM) and
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The importance and complexity of the problems associated with coordinating multiple organizations to configure value propositions for customers has drawn the attention of multiple disciplines. In an effort to clarify and consolidate terms, this conceptual research examines both supply chain management (SCM) and system of systems (SoS) literature to postulate, from a value-chain perspective, what roles integration and collaboration play in helping supply chains satisfy customer requirements. A literature review analysis was used to identify the commonalities and differences between supply chain management and system of systems approaches to examining interfirm coordination of value creation efforts. Although a framework of integration and collaboration roles in value creation is proposed, further empirical testing of the concept is required to substantiate initial conclusions. The concepts proposed may help clarify where strategic and operational managers need to focus their efforts in coordinating supply chain member firms. The incorporation of SoS engineering into the supply chain field will draw the linkage between the constituent principles, and concepts of Systems Theory as appropriate for the supply chain management field. This is the first effort to reconcile two separate but parallel scholarship streams examining the coordination of multiple organizations in value creation. This research shows that there are some methodologies, principles, and methods from the SoS field that can supplement supply chain management research. Mainly due to a unit of analysis issue, systems based approaches have not been in the mainstream of supply chain management field development. Full article
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Open AccessArticle
A Measure of the Non-Determinacy of a Dynamic Neighborhood Model
Systems 2017, 5(4), 49; doi:10.3390/systems5040049 -
Abstract
In this paper we define a non-deterministic dynamic neighborhood model. As a special case, a linear neighborhood model is considered. When a non-deterministic neighborhood model functions, it is possible to introduce a restriction on the number of active layers, which will allow the
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In this paper we define a non-deterministic dynamic neighborhood model. As a special case, a linear neighborhood model is considered. When a non-deterministic neighborhood model functions, it is possible to introduce a restriction on the number of active layers, which will allow the variation of the non-determinism of the model at each moment of time. We give the notion of the non-determinacy measure and prove that it has the properties of a probability measure. We formulate the problem of reachability with partially specified parameters, layer priorities, and the non-determinacy measure. An algorithm for solving the attainability problem for a neighborhood model with variable indeterminacy and layer priorities is presented. An example of its solution is shown, which shows that when the priorities are compared and the measure of non-determinism is used, the solution of the problem can be obtained more quickly than by a method that does not use priorities. Full article
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Open AccessArticle
Packageability as an ‘Ility’ for Systems Engineering
Systems 2017, 5(4), 48; doi:10.3390/systems5040048 -
Abstract
The usefulness of packageability as one of the ‘ilities’ for systems engineering was investigated. It was found that packageability plays an important role in a multitude of systems, and it was investigated in several ways. First, a brief analysis showed that at least
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The usefulness of packageability as one of the ‘ilities’ for systems engineering was investigated. It was found that packageability plays an important role in a multitude of systems, and it was investigated in several ways. First, a brief analysis showed that at least two criteria must be met for something to be considered an ility. These criteria are that the ility often manifests itself after the system is deployed, and that the potential ility must not simply be a persistent physical characteristic. It was shown that packageability meets both requirements. Second, six different systems were examined, revealing nine general ways packageability is used. They provide a way for system engineers to recognize packageability as a non-functional system property. The usefulness of packageability as a top-level non-functional system property is shown, as well as for sub-systems and components. A working definition of packageability is then proposed. Finally, a detailed treatment of packageability is presented for radar systems with transmit–receive modules. Packageability was shown to be a useful ility category that can add value to stakeholders, and that captures real system features that are not captured by other ilities. This work demonstrates that packageability should be considered as an ility for systems engineers. Full article
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Open AccessArticle
On Using Ilities of Non-Functional Properties for Subsystems and Components
Systems 2017, 5(3), 47; doi:10.3390/systems5030047 -
Abstract
The use of ilities for systems engineering of subsystems and components is investigated. Prior work on ilities has emphasized or restricted their application to system level, non-functional properties. The premise of this work is that ilities can be applied with benefit, and in
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The use of ilities for systems engineering of subsystems and components is investigated. Prior work on ilities has emphasized or restricted their application to system level, non-functional properties. The premise of this work is that ilities can be applied with benefit, and in some cases out of necessity, to lower levels of systems as well. The veracity of this premise is established by providing examples that demonstrate how some ilities are passed and used as a non-functional property of electrical and structural subsystems in aircraft. It is further demonstrated that flowing ilities down to the subsystem level is not only a useful practice for systems engineers, it can also be an essential step to ensure that customer needs are actually met by the system under design or service. Systems engineers often lack the detailed knowledge of the subsystems or components required to translate ilities into functional requirements. Thus, the system ilities are passed down and translated from non-functional to functional requirements by subject matter experts. We first discuss the definition, characteristics and scope of ilities. Then, we formulate the application of ilities at a subsystem level. Next, we show aircraft engineering examples for ilities applications. The application process is formalized with diagrams, and ilities’ relation to system architecture engineering is discussed. The work concludes with a summary and suggestions for future work. Full article
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