The deployment of Digital Twins (DTs) for decision-making support is rapidly expanding in different industries. DTs are cross-disciplinary hybrid systems that combine elements from various engineering domains. Their diverse services require hybrid modeling and simulation techniques to replicate complex system behaviors. Therefore, their inherent complexity requires comprehensive verification and validation frameworks. In the state-of-the-art, verification and validation of DTs are mostly narrowed down to simulation models. However, it needs to extend beyond that and encompass a broader scope. Thus, it is crucial to accurately identify the scope of verification and validation that encompasses data integration, model fidelity, and service functionality. The main contribution of this paper is to propose a verification and validation framework that synergistically integrates white-box and black-box testing techniques to systematically verify and validate data, models, and services of DTs throughout the development life cycle. It leverages an agile methodology to enable iterative and continuous development, verification, and validation. It employs white-box testing using formal methods and black-box testing using software testing techniques, respectively, for verification and validation. A case study is presented that utilizes the framework to develop, verify, and validate a DT. Ultimately, a set of defined evaluation metrics is tracked throughout the development life cycle in the case study to demonstrate the effectiveness of the agile V&V framework proposed.

Digital Twins are considered a key software system in diverse industries. They allow for replicating the behavior of complex physical systems, thereby enabling real-time monitoring and enhancing decision-making capabilities. The inherent complexity and evolving nature of digital twins pose significant challenges in maintaining their long-term reliability. Consequently, prioritizing the testability of digital twins is crucial to ensure their accuracy over time. Given the novelty of the field, there is a notable research gap in the literature on testing strategies and methods for digital twins. Additionally, most of the research works have adopted a monolithic architecture for the development of digital twins. The internal tight coupling in this architecture and the constant evolution of digital twins results in retesting and redeployment of the entire software after any change. This makes the monolithic architecture inefficient for addressing the testability of complex and dynamic digital twins. This research proposes a microservice-based architecture for digital twins that addresses testability challenges. Furthermore, leveraging testing strategies and design patterns in this architecture can potentially increase testability, modularity, and internal decoupling of digital twins.

The European Climate Law aims to combat energy-inefficient buildings by prohibiting the rental of the most energy-consuming housing units. These restrictions, designed to address greenhouse gas emissions and energy conservation, are at the forefront of metropolitan concerns as part of their efforts toward ecological transition. MUST-B (integrated land Use Model—Transport application to the Urban area) is a Land Use Transport Interaction (LUTI) model that simulates households and workplaces location choices. It models and simulates the interaction of both the population of an urban area through their residential choices with activities and jobs, as well as the various transportation modes to meet daily mobility needs. This agent-based tool allows for understanding the complexity of an urban area based on individual behaviors giving rise to collective phenomena. In this article, our focus is on the “land use” component of the tool, specifically emphasizing the “multi-agent” aspect by developing two populations of agents in close interaction during the simulation: households and their residences. We also explore an example application related to a European regulation for the withdrawal of high-energy-consumption housing.

The increasing use of Digital Twin (DT) solutions in different domains demands for development of Verification and Validation (V&V) frameworks to guarantee the effectiveness of the implemented DTs. However, a considerable research gap has been identified in this field. Current state of the research is mainly concentrated on V&V of models in DTs and excluded important aspects such as data interoperability and functionality of DT services. To extend the scope of V&V, it is crucial to include these aspects. This paper presents a novel framework for V&V of DTs that considers all the mentioned aspects. This framework combines formal methods with software testing methods for V&V. It utilizes formal methods in a top-down manner and it will then use the software testing methods in a bottom-up manner.

Urban transport and housing location are key points for metropolises because they are subject of measures in the context of ecological transition and to reduce greenhouse gas emissions. A LUTI (Land Use and Transport Interaction) model’s objectives is to represent and simulate the interactions between an agglomeration’s population through its residential decisions, and transportation used to meet daily mobility needs. In this article, we propose to extend LUTI models by adding housing and workplaces as agents in order to test European political policies such as low-emission areas or the prohibition on poorly insulated housing.

In order to limit greenhouse gas emissions, urban travel is a central point of interest for metropolises as part of their actions in favor of ecological transition. MUST-B is a land use transport interaction (LUTI) model that simulates the location choices of households and jobs. It models and simulates the interaction both of the population of an agglomeration through its residential choices with activities and jobs, but also the different modes of transport to satisfy daily mobility. This tool based on the agent-based paradigm makes it possible to apprehend the complexity of an urban territory from individual behaviors giving rise to collective phenomena. In this article, we concentrate on the “transport” part of the tool, show how the elaboration and the calibration of this model are done, and study an example of its reaction to a variation of setpoints.

Classical simulation methods become not flexible and performant enough in complex models, necessitating the use of a distributed simulation technique to split the load and heterogeneity into separate sub-components and manage the simulation time between them. In this type of simulation, interoperability and reusability issues arise and should be addressed. The IEEE High-Level Architecture (HLA) standard for distributed simulation emphasizes federates interoperability and reusability, as well as time management and advanced data distribution techniques. This paper presents the methodologies and techniques used to develop the HLA federates, as part of the Simulation Exploration Experience (SEE) project, to virtually recreate a mission on the moon. This project is organized by the National Aeronautics and Space Administration (NASA) and the Simulation Interoperability Standards Organization (SISO). For each SEE component, an HLA interface was developed to make it compliant with other SEE federates and reusable during the simulation run. Based on HLA mechanisms, heterogeneous components with an HLA interface were able to interexchange objects/attributes and interactions/parameters.

Hospitals and other healthcare settings use various simulation methods to improve their operations, management, and training. The COVID-19 pandemic, with the resulting necessity for rapid and remote assessment, has highlighted the critical role of modeling and simulation in healthcare, particularly distributed simulation (DS). DS enables integration of heterogeneous simulations to further increase the usability and effectiveness of individual simulations. This article presents a DS system that integrates two different simulations developed for a hospital intensive care unit (ICU) ward dedicated to COVID-19 patients. AnyLogic has been used to develop a simulation model of the ICU ward using agent-based and discrete event modeling methods. This simulation depicts and measures physical contacts between healthcare providers and patients. The Unity platform has been utilized to develop a virtual reality simulation of the ICU environment and operations. The high-level architecture, an IEEE standard for DS, has been used to build a cloud-based DS system by integrating and synchronizing the two simulation platforms. While enhancing the capabilities of both simulations, the DS system can be used for training purposes and assessment of different managerial and operational decisions to minimize contacts and disease transmission in the ICU ward by enabling data exchange between the two simulations.

In order to limit greenhouse gas emissions and in the objective of the ecological transition, land-use and urban travel is a central point of interest for all metropolises. SIMUTEC is a platform that distinguishes itself from other tools by its strong transdisciplinary. It is a multisectoral agent-based simulation designed to help territories in their decision making. In this paper, we present a platform that integrates the complexity of the urban phenomenon by modeling all the fundamental mechanisms related to the occupation of space, transports and congestion. The objective of this paper is to present the platform architecture from a high-level point of view, and describe opportunities to use distributed simulation in this context. Moreover, in order to help with decision, the platform contain a 3D render engine (M-3D) and a tool for calculating indicators on energy consumption, greenhouse gas emission and pollutants

The digital twins of production systems are one of the pillars of the Indus-try of the Future. Despite numerous on-going research and development initiatives the verification and validation of the digital twin remains a major scientific obstacle. This work proposes a simulation-based approach to achieve this goal: support Digital Twin verification and validation through the definition of a dedicated framework. A simulation model is used in place of the real-world system for ensuring the digital twin behaves as expected and for assessing its proper interoperability with the system to be twinned with. Then the simulation model is replaced by the real-world sys-tem, to interoperate with the verified and validated digital twin. With such an approach, the interoperability middleware, i.e. the IoT between the sys-tem and its digital twin can also be modeled, simulated, verified and vali-dated. Consequently, an optimized solution can be built for an entire value chain, from the system to its digital twin and conversely.

MBSE (Model Based Systems Engineering) is considered a valuable and effective approach not only in engineering domains, although it appears to bring a potential assistance to artistic visions and initiatives. The cross-domain capitalization is the key to further innovation and advances in technology. This paper describes an MBSE approach, applied to the development of a complex multi-component arrangement system, to generate an automated music arrangement for any melody, with a harmonically correct result. The user introduces the melody in the form of a MIDI file. The system analyzes the melody, detects the scale, then follows algorithms based on thorough theoretical and harmonic studies, to finally generate the arrangement based on the selected music genre (classical, jazz, pop, etc.). Compared to other existing systems in the market, the developed system largely reduces the dissonance between the melody and the arrangement, which makes the final arrangement a good accompaniment to the melody.

Different heterogeneous simulation components can be integrated to produce a more effective complex global system. The IEEE High-Level Architecture (HLA) is an international standard that promotes interoperability and reusability for distributed simulation (DS). This paper proposes a DS system that integrates an agent-based and discrete-event simulator with a 3D game engine to build virtual reality (VR) applications that replicate real environments. In this case study, AnyLogic is used as an agent-based and discrete event simulator to simulate the process flow and COVID-19 transmission inside the University Health Network dialysis unit, Toronto, Canada. Unity game engine delivers the 3D modelling replicating the real architecture and environment of the dialysis unit. The HLA standard plays a major role in the integration of AnyLogic and Unity to produce a more effective and powerful DS system for VR applications.

Nowadays, industries are implementing heterogeneous systems from different domains, backgrounds, and operating systems. Manufacturing systems are becoming more and more complex, which forces engineers to manage the complexity in several aspects. Technical complexities bring interoperability, risk management, and hazards issues that must be taken into consideration, from the business model design to the technical implementation. To solve the complexities and the incompatibilities between heterogeneous components, several distributed and cosimulation standards and tools can be used for data exchange and interconnection. High-level architecture (HLA) and functional mockup interface (FMI) are the main international standards used for distributed and cosimulation. HLA is mainly used in academic and defense domains while FMI is mostly used in industry. In this article, we propose an HLA/FMI implementation with a connection to an external business process-modeling tool called Papyrus. Papyrus is configured as a master federate that orchestrates the subsimulations based on the above standards. The developed framework is integrated with external heterogeneous components through an FMI interface. This framework is developed with the aim of bringing interoperability to a system used in a power generation company.

La modelisation et la simulation (M&S) sont des etapes importantes dans le processus de conception. La complexite grandissante des systemes tend a accroitre le besoin de segmenter les modeles, leurs executions, se dirigeant vers des approches distribuees. Papyrus, un modeleur open source permettant la M&S UML/SysML via le standard fUML. Cependant, Papyrus n'est pas en mesure de gerer la simulation distribuee (SD). Dans cet article, nous proposons une SD composee de plusieurs instances de Papyrus. L'objectif principal est de synchroniser l'execution de ces instances, en utilisant le standard Functional Mock-up Interface (FMI) pour la communication. Neanmoins, la norme FMI n'incluant pas nativement la gestion du temps, nous proposons d'utiliser le standard High-Level Architecture (HLA) pour gerer la temporalite entre les instances de simulation Papyrus, via la communication FMI.

In order to control manufacturing systems, managers need risk and performance evaluation methods and simulation tools. However, these simulation techniques must evolve towards being multiperformance, multiactor, and multisimulation tools, and this requires interoperability between those distributed components. This paper presents an integrated platform that brings interoperability to several simulation components. This work expands the process modeling tool Papyrus to allow it to communicate with external components through both distributed simulation and cosimulation standards. The distributed modeling and simulation framework (DMSF) platform takes its environment into consideration in order to evaluate the sustainability of the system while integrating external heterogeneous components. For instance, a DMSF connection with external IoT devices has been implemented. Moreover, the orchestration of different smart manufacturing components and services is achieved through configurable business models. As a result, an automotive industry case study has successfully been tested to demonstrate the sustainability of smart supply chains and manufacturing factories, allowing better connectivity with their real environments.

Modeling and Simulation (M&S) are important steps in design process. Increasing the complexity of engineered system tend to raise Distributed Simulation. Papyrus, an open source UML/SysML modeler of the Eclipse foundation provides a tool to model and simulate these two languages thanks to the fUML standard. However, Papyrus is not yet able to deal with Distributed Simulation. In this paper, we propose a Distributed Simulation composed of several Papyrus instances. Each made of an UML Profile, a Moka extension, and software architecture. The main objective is to synchronize the execution of these Papyrus instances. We are using Functional Mockup Interface (FMI) to enable communication between them. Nevertheless, the FMI standard does not natively include time management rules. Indeed, we propose to use the High Level Architecture (HLA) standard to handle time management between Papyrus simulations instance, through FMI communication.

Modeling and Simulation (M&S) are important steps in the design of industrial systems and production plants. They help in anticipating and understanding these complex systems in order to make decisions about strategic implementations before effective development. Once the models are satisfyingly built, namely they correctly reflect the system, the simulation can offer many behavioral information to the user. In this paper, we are proposing to integrate risk management, hazard generation, and complexity issues in process modeling with data coming from industrial context: polar power plant design. In this context, risks and hazards must be modeled, but are too large to be in the main model. For this purpose, the paper presents some extensions to the modeling and simulation open source tool: Papyrus. This proposition consists in developing the Papyrus features for outsourcing risks and hazards out of the model, exporting simulation's data in different components for decision making, and implementing distributed simulation mechanisms for dealing with reusability, and interoperability of components.

Modeling and Simulation is attempting to tackle more and more complex systems, which makes their design highly challenging. Complex systems' Modeling and Simulation (M&S) require the consideration of several simultaneous points of view and involve skills from different scientific and technical fields. Distributed Simulation domain answer the question of coupling and running together heterogeneous components, e.g. IEEE 1516-2010 - High Level Architecture is one of the most used standard. Also, Functional Mockup Interface provide standard designed for the coupling of simulation tools (simulator coupling, tool coupling), and coupling with subsystem models, which have been exported by their simulators together with its solvers as runnable code. In this paper, we aim to provide bridge between HLA and FMI standard in order to couple those technologies.