Systems — Open Access Journal

The simulation of population dynamics and social processes is of great interest in nonlinear systems. Recently, many scholars have paid attention to the possible applications of population dynamics models, such as the competitive Lotka–Volterra equation, in economic, demographic and social sciences. It was found that these models can describe some complex behavioral phenomena such as marital behavior, the stable marriage problem and other demographic processes, possessing chaotic dynamics under certain conditions. However, the introduction of external factors directly into the continuous system can influence its dynamic properties and requires a reformulation of the whole model. Nowadays most of the simulations are performed on digital computers. Thus, it is possible to use special numerical techniques and discrete effects to introduce additional features to the digital models of continuous systems. In this paper we propose a discrete model with controllable phase-space volume based on the competitive Lotka–Volterra equations. This model is obtained through the application of semi-implicit numerical methods with controllable symmetry to the continuous competitive Lotka–Volterra model. The proposed model provides almost linear control of the phase-space volume and, consequently, the quantitative characteristics of simulated behavior, by shifting the symmetry of the underlying finite-difference scheme. We explicitly show the possibility of introducing almost arbitrary law to control the phase-space volume and entropy of the system. The proposed approach is verified through bifurcation, time domain and phase-space volume analysis. Several possible applications of the developed model to the social and demographic problems’ simulation are discussed. The developed discrete model can be broadly used in modern behavioral, demographic and social studies. Full article

This work studies a hybrid manufacturing‒remanufacturing system with a sorting line and disposal. In particular, it models a company that collects used product, remanufactures returned products that have been evaluated as suitable to be recovered, and manufactures new products to satisfy customer demand. Specifically, the system is modeled as a multilevel inventory system, with three types of stock (used products inventory, recoverable inventory, and serviceable inventory), each characterized by an inventory holding cost, and three limited capacity resources: a sorting line, which enables the company to distinguish those returns that are remanufacturable from those that are not; a remanufacturing line to carry out operations on sorted remanufacturable returns; and a manufacturing line to produce new products in order to satisfy customer demand. Each resource is characterized by a setup cost, as well as a constant production rate, while each type of stock is associated with an inventory holding cost. The aim of the paper is to develop a model for the considered production system in order to minimize the setup and inventory holding costs. In particular, the objective is to evaluate the behavior of a controllable disposal rate with the minimization of the total cost function, by considering the effect on the remanufacturing and manufacturing lines. Full article

Geometric-Zeno behaviour is a highly challenging problem in the analysis (including simulation) of hybrid systems. Geometric-Zeno can be defined as an infinite number of discrete mode switches in a finite time interval. Typically, for hybrid models exhibiting geometric-Zeno, the numerical simulation either halts or produces false results, because an infinite number of discrete events occur in a given simulation time-step. In this paper, we provide formal methods for regularization of geometric-Zeno behaviour by using a non-standard analysis. In particular, we provide formal conditions for the existence of geometric-Zeno in hybrid systems, and we propose methods to allow geometric-Zeno executions to be continued beyond geometric-Zeno limit points. The concepts are illustrated with a case study throughout the paper. Full article

In this paper we summarize the research on Systems Thinking for business management and explore several examples of business failures due to a lack of application of Systems Thinking, with an ultimate goal of offering a Systems Thinking approach that is useful to all levels of management. Although there is significant literature aimed at facilitating Systems Thinking in organizational management, there remains a lack of adoption of Systems Thinking in mainstream business practice. This is perhaps because the literature does not reduce high-level Systems Thinking principles to hands-on, practical protocols that are accessible for typical managers, thus limiting the working application of Systems Thinking concepts to researchers and consultants who specialize in the field. The goal of this work is to not only elaborate on the high-level ideals of System Thinking, but also to articulate a more precise and practical hands-on approach that is useful to all levels of business managers. Full article

Critical infrastructure is a complex system whose disruption or failure results in significant impacts on state interests, i.e., territorial security, economy, and the basic needs of the population. The current European Critical Infrastructure Protection Model does not allow the direct identification of critical elements at the regional level. Based on this, the paper brings a proposal for a unified system of critical infrastructure design based on a bottom-up approach. It is a progressive approach, utilizing contemporary trends in the application of science-based knowledge to critical infrastructure. A holistic view of this issue allows us to take into account the needs and preferences of the population, the preferences of the stakeholders and the local conditions of the region under consideration. The novelty of this approach is seen, in particular, in the identification of regional critical infrastructure elements through an integral assessment of these elements’ failure impact, not only on the dependent subsectors, but also on the population (population equivalent) in the assessed region. The final part of the paper presents a case study demonstrating the practical application of the proposed system to the road infrastructure in the Pardubice Region of the Czech Republic. Full article

Team effectiveness models in the literature are primarily concentrated on traditional teams, with few involving the multiteam system (MTS) level of analysis in the model. Teams achieve their goals by managing both teamwork (e.g., interpersonal, effective, motivational, cognitive) and taskwork (e.g., strategy, goal setting, project management) activities. When MTSs are involved, multiple teams manage their own teamwork and taskwork activities, while leadership must be in place to coordinate these activities within and between teams in order to achieve the organization’s goal (the MTS’s goal). This research study conducted a systematic review of current team effectiveness frameworks and models. A narrative-based method for theorizing was utilized to develop a new MTS team effectiveness framework. This research contributes to the MTS literature by providing a new formula for team effectiveness at both the team level (team effectiveness formula) and the MTS level (MTS team effectiveness formula). This research aids managers, practitioners, and researchers by providing a tool that accounts for all levels and temporal processes. Full article

The myriad of problems facing the world today are increasingly complex, dynamic, and transcend multiple domains. This necessitates the need for trans-disciplinary approaches capable of providing a framework to help solve these problems. Systems thinking provides the skills necessary for people to approach these types of problems. However, a lack of awareness and understanding of systems thinking hinders a potential systems-literate and systems-capable society. Systems thinking is comprised of four underlying concepts or skills: distinction-making, organizing systems, inter-relating, and perspective-taking. The path to becoming a systems thinker follows a process comprised of three levels—sensibility (awareness of systems), literacy (knowledge of systems), and capability (understanding of systems)—repeated across multiple learning phases. During this research study, a method was defined to measure whether non-experts learned the underlying systems thinking concepts according to this learning process. An experiment was conducted with 97 middle and high school students who were asked to draw a fish-tank system before and after being taught to apply the systems thinking concepts as skills for identifying elements, interactions, and roles/purposes. The results provide evidence to conclude that student learning of systems thinking significantly increased from the first drawing to the second drawing. Full article

Levels of Automation (LOA) provide a method for describing authority granted to automated system elements to make individual decisions. However, these levels are technology-centric and provide little insight into overall system operation. The current research discusses an alternate classification scheme, referred to as the Level of Human Control Abstraction (LHCA). LHCA is an operator-centric framework that classifies a system’s state based on the required operator inputs. The framework consists of five levels, each requiring less granularity of human control: Direct, Augmented, Parametric, Goal-Oriented, and Mission-Capable. An analysis was conducted of several existing systems. This analysis illustrates the presence of each of these levels of control, and many existing systems support system states which facilitate multiple LHCAs. It is suggested that as the granularity of human control is reduced, the level of required human attention and required cognitive resources decreases. Thus, it is suggested that designing systems that permit the user to select among LHCAs during system control may facilitate human-machine teaming and improve the flexibility of the system. Full article

System dynamics implementations of financial statements are currently limited by the lack of a simple to use, yet sufficiently detailed model that operationally replicates the accounting reporting process for the income statement, balance sheet, cash flow statement, and statement of changes in owners’ equity. While system dynamics accounting structures exist, they are inconsistently applied in the literature. In this paper, we offer a comprehensive accounting model in the hope that academics and practitioners will use its structures to better represent accounting reports in their projects. Full article

Automation and autonomous systems are quickly becoming a more engrained aspect of modern society. The need for effective, secure computer code in a timely manner has led to the creation of automated code repair techniques to resolve issues quickly. However, the research to date has largely ignored the human factors aspects of automated code repair. The current study explored trust perceptions, reuse intentions, and trust intentions in code repair with human generated patches versus automated code repair patches. In addition, comments in the headers were manipulated to determine the effect of the presence or absence of comments in the header of the code. Participants were 51 programmers with at least 3 years’ experience and knowledge of the C programming language. Results indicated only repair source (human vs. automated code repair) had a significant influence on trust perceptions and trust intentions. Specifically, participants consistently reported higher levels of perceived trustworthiness, intentions to reuse, and trust intentions for human referents compared to automated code repair. No significant effects were found for comments in the headers. Full article

Recent research on global fisheries has reconfirmed a 2006 study that suggested global fisheries would collapse by 2048 if fisheries were not better managed and trends reversed. While many researchers have endorsed rights-based fishery management as a key ingredient for successful management and rebuilding fisheries, in practice the results are mixed and success varies by geographic region. Rights-based approaches such as individual transferable quota (ITQ) provide a necessary help to the important task of rebuilding fisheries, but we assert that they are sometimes less effective due to the human component of the system. Specifically, we examine the issue of setting an appropriate total allowable catch (TAC) in Individual Transferable Quota (ITQ) systems. ITQ are designed on the premise that economic ownership is sufficient incentive to entice fishers to be stewards of the resource. However, an excessive short-term orientation and an affective risk response by fishers can overwhelm feelings of ownership. In such cases, fishers and fishing communities can exert sufficient pressure on TAC setting and reduce the effectiveness of ITQ fisheries toward rebuilding fish stocks. Based on our analysis that draws on cognitive psychology, short-termism, and affective risk, we suggest heightened and wider democratic involvement by stakeholders in co-managed ITQ fisheries along with potential pilot tests of government-assisted financial transfers to help in transitioning ITQ fisheries to sustainable states. Full article

Systems thinking is an approach to reasoning and treatment of real-world problems based on the fundamental notion of ‘system.’ System here refers to a purposeful assembly of components. Thus, systems thinking is aimed at understanding relationships between components and their overall impact on system outcomes (i.e., intended and unintended) and how a system similarly fits in the broader context of its environment. There are currently several distinct flavors of systems thinking, both in practice and scholarship; most notably in the disciplines of systems science, systems engineering, and systems dynamics. Each of these, while similar in purpose, has a distinct history and a rich set of methods and tools for various application contexts. The WPI Systems Thinking Colloquium held on 2 October 2019 was aimed at exploring the diversity of perspectives on systems thinking from these disciplines. The colloquium brought together world-renowned experts from both industry and academia to share insights from their research and practice. This paper offers a compilation of summaries of the presentations given. Full article

This paper traverses the domains of leadership and decision-making within various types of systems with different levels of complexity. The article presents some background about both leadership and decision-making, and then explores the concept of leadership decision-making and some of the factors involved. The paper then reviews complex systems and provides examples to differentiate complex systems from other systems. Finally, these strands are brought together with a consideration of leadership decision-making in complex systems and presentation of a framework to assist managers faced with decision-making in complexity, based on data collected in a survey. The aim and practical contribution of this paper is to improve the outcomes of leadership decision-making within complex systems, based upon the findings and on a decision aid model derived from them. The paper, therefore, should help people in real life and leaders within organizational settings to improve their decision-making effectiveness within the ever-increasing range of complex situations which are now widely encountered. Full article

The United Nations 2030 Agenda for Sustainable Development set the target of halving per capita global food waste and reducing food losses, including post-harvest losses. Food loss is a significant global challenge rising from the decrease in food quantities available for human consumption because of decisions and actions taken by food manufacturers and suppliers before it even reaches the retail market. Food loss within the Norwegian farmed salmon post-harvest processing system could be reduced by making change in the system’s behavior. This study, by following systems engineering principles, aimed to develop insight into the salmon post-harvest processing system’s behavioral dynamics causing current food loss and to consider conceptual keys to solutions. This study tied the food loss problem to systemic behavior of byproducts downgrading to non-food uses as the major cause. The decisions made on the materials flow are based on product design, quality control, and environmental solutions. Making a decision to conserve byproduct materials by prioritizing keeping them within the human food chain requires supportive data on their true potential as a food source. The system’s information pool that decision makers rely on can be fortified with the system’s engineering multidisciplinary outcomes that will enable the necessary paradigm shift to achieve the quested food loss reduction. Full article

As systems continue to grow in scale and complexity and have to operate safely in challenging disruptive environments, system safety and resilience has become a critical requirement. This recognition has drawn attention to the concept of resilience, which has different definitions and several different interpretations that tend to be domain specific. For example, resilience in health care clinics means something quite different than resilience in self-driving cars, or energy grids. This paper reviews the different characterizations of resilience and assesses their value proposition in realizing engineered resilient systems. This paper emphasizes the importance of systems modeling in engineering resilient systems and presents an overarching methodology that employs different modeling approaches for operational tasks as a function of problem context. This paper specifically focuses on systems modeling in partially observable and potentially hostile environments. It discusses the need for system model verification, which is key to safety, and system flexibility and adaptability, which are key to resilience. It introduces a formal, probabilistic modeling construct called the “resilience contract.” This construct employs a state-based representation that formalizes the concept of resilience while enabling system model verification and affording requisite flexibility for adaptation and learning. The key findings of our research are that different system modeling approaches and algorithms are needed based on mission tasks and operational context; adaptive capacity and continual adaptability are the two promising characterizations of resilience that can be cost-effectively realized in real-world systems; and the resilience contract construct is an effective means for probabilistic verification of system model correctness while affording flexibility needed for adaptation and learning. Collectively, these findings contribute to the body of knowledge in both model-based systems engineering (MBSE) and engineered resilient systems. Full article

New and unsaturated markets are predominantly located in countries with low incomes. To successfully establish businesses in these new markets, an increasing globalization of value creation is necessary. The integration of these new markets is challenged by their dynamics, turbulence and regulation. Above all, an initially low and volatile demand as well as high barriers for market entry must be counteracted by economical small-series production. As market development is a major challenge for Small and Medium Enterprises (SME), knowledge about the impact of local conditions on their production strategy decisions is essential. Therefore, we design a recurrent fuzzy model combining country- and company-specific input factors as well as internal production parameters to obtain a transparent and reproducible impact statement. The model allows a simplified development of the expert knowledge base by mapping the influences in two steps. The application of the designed model is based on the example of the aCar mobility project, within which an electric vehicle was designed for local value creation in Africa. By applying the model for different African countries, strategy sensitivities can be identified, and recommendations derived. Full article

The realization of large-scale complex engineered systems is contingent upon satisfaction of the preferences of the stakeholder. With numerous decisions being involved in all the aspects of the system lifecycle, from conception to disposal, it is critical to have an explicit and rigorous representation of stakeholder preferences to be communicated to key personnel in the organizational hierarchy. Past work on stakeholder preference representation and communication in systems engineering has been primarily requirement-driven. More recent value-based approaches still do not offer a rigorous framework on how to represent stakeholder preferences but assume that an overarching value function that can precisely capture stakeholder preferences exists. This article provides a formalism based on modal preference logic to aid in rigorous representation and communication of stakeholder preferences. Formal definitions for the different types of stakeholder preferences encountered in a systems engineering context are provided in addition to multiple theorems that improve the understanding of the relationship between stakeholder preferences and the solution space. Full article

The operating landscape of 21st century systems is characteristically ambiguous, emergent, and uncertain. These characteristics affect the capacity and performance of engineered systems/enterprises. In response, there are increasing calls for multidisciplinary approaches capable of confronting increasingly ambiguous, emergent, and uncertain systems. System of Systems Engineering (SoSE) is an example of such an approach. A key aspect of SoSE is the coordination and the integration of systems to enable ‘system-of-systems’ capabilities greater than the sum of the capabilities of the constituent systems. However, there is a lack of qualitative studies exploring how coordination and integration are achieved. The objective of this research is to revisit SoSE utility as a potential multidisciplinary approach and to suggest ‘governance’ as the basis for enabling ‘system-of-systems’ coordination and integration. In this case, ‘governance’ is concerned with direction, oversight, and accountability of ‘system-of-systems.’ ‘Complex System Governance’ is a new and novel basis for improving ‘system-of-system’ performance through purposeful design, execution, and evolution of essential metasystem functions.’ Full article