Gregory Zacharewicz

G-DEVS/HLA Environment for Distributed Simulations of Workflows

We present a Workflow environment allowing distributed simulation based on DEVS/G-DEVS formalisms. A description language for Workflow processes and an automatic transformation of a Workflow into a G-DEVS model have been defined. We then introduce a new distributed Workflow Reference Model with HLA-compliant Workflow components. We detail the HLA objects shared between Workflow federates and present the publishing/subscribing status of each of these federates. Finally, we illustrate the use of this distributed environment with an example of a Microelectronic production Workflow.

A model-driven approach to multidisciplinary collaborative simulation for virtual product development

The design and development of complex artifacts and systems is shifting towards a distributed and collaborative paradigm. The simulation environments for such a paradigm, therefore, need to take into account the cooperation between design teams, i.e. supporting multidisciplinary simulation in a distributed environment. However, current simulation tools can not fulfil this requirement as they have been developed to solve the specific problems from different disciplines. Although its already possible to perform multidisciplinary simulations by using several tools together, it is very difficult to implement it when these tools are distributed on the Internet. A solution which can support the integration of distributed simulation models at run-time is presented, involving a computational infrastructure and a high-level modelling approach. Specifically, the infrastructure is constructed by a novel combination of two distributed computing techniques to implement the synchronization of distributed models, as well as to ensure the interoperability at run-time. In addition, a model-driven approach is developed to bridge the high-level model of a simulation system and the infrastructure which implements this model. The solution is evaluated by making a comparison with other approaches, as well as by developing a prototype tool. Its shown in the evaluation that (1) it is viable to develop multidisciplinary simulations in a distributed environment using this solution; (2) the model-driven approach allows designers to focus only on the high-level structure of a design without getting concerned with the details of the infrastructure.

Towards a sustainable interoperability in networked enterprise information systems

Sustaining interoperability in enterprise networks is the next research challenge.Not understanding the impact of a single system change may cause network failures.Pervasive information models and EA can support dynamic interoperability enablers.Combined use of model-driven and knowledge-based approaches can improve NG-EIS.We present and discuss the sustainable interoperability research framework. In a turbulent world, global competition and the uncertainty of markets have led organizations and technology to evolve exponentially, surpassing the most imaginary scenarios predicted at the beginning of the digital manufacturing era, in the 1980s. Business paradigms have changed from a standalone vision into complex and collaborative ecosystems where enterprises break down organizational barriers to improve synergies with others and become more competitive. In this context, paired with networking and enterprise integration, enterprise information systems (EIS) interoperability gained utmost importance, ensuring an increasing productivity and efficiency thanks to a promise of more automated information exchange in networked enterprises scenarios. However, EIS are also becoming more dynamic. Interfaces that are valid today are outdated tomorrow, thus static interoperability enablers and communication software services are no longer the solution for the future. This paper is focused on the challenge of sustaining networked EIS interoperability, and takes up input from solid research initiatives in the areas of knowledge management and model driven development, to propose and discuss several research strategies and technological trends towards next EIS generation.

An ontology-driven framework towards building enterprise semantic information layer

Enterprises Information Systems (EIS) have been applied for decades in Computer-Aided Engineering (CAE) and Computer-Aided Design (CAD), where huge amount of increasing data is stored in the heterogeneous and distributed systems. As systems evaluating, system redesign and reengineering are demanded. A facing challenge is how to interoperate among different systems by overcoming the gap of conceptual heterogeneity. In this article, an enlarged data representation called semantic information layer (SIL) is described for facilitating heterogeneous systems interoperable. SIL plays a role as mediation media and knowledge representation among heterogeneous systems. The SIL building process is based on ontology engineering, including ontology extraction from relational database (RDB), ontology enrichment and ontology alignment. Mapping path will maintain the links between SIL and data source, and query implementation and user interface are for retrieving data and interacting with end users. We described fully a practical ontology-driven framework for building SIL and introduced extensively relevant standards and techniques for implementing the framework. In the core part of ontology development, a dynamic multi-strategies ontology alignment with automatic matcher selection and dynamic similarity aggregation is proposed. A demonstration case study in the scenario of mobile phone industry is used to illustrate the proposed framework.

Product-service systems scenarios simulation based on G-DEVS/HLA: Generalized discrete event specification/high level architecture

In the past decade, personal customers expected manufacturing companies to provide them with a physical product with, nonetheless, some basic additional services. Currently, customers expect a more comprehensive solution, integrating both a physical product and non-physical services, which explains why companies have started to propose Product-Service Systems (PSS). The underlying objective of profitability can be attained if the system is designed, based on system use, to avoid waste, and if services are developed jointly with products. Although all the requisite conditions are well-known, the optimal way to satisfy them is not formalized or even guided by any clear methodology. This paper proposes to create PSS models to be simulated in different service scenarios based on G-DEVS/HLA. The simulation results provide pointers to help decision maker choose between several PSS design scenarios to be manufactured. A case study from the toy industry is used to illustrate the proposed methodology.

Distributed simulation platform to design advanced RFID based freight transportation systems

RFID systems, known to improve supply chains performances, are little implemented so far in industry, particularly in the field of transport, due to the high economic investment it requests in comparison to other existing solutions. However, their benefits may be theoretically proved by using a distributed simulation platform to support the design and test of any technical solution and organizational approach devoted to optimize RFID-based logistics systems. This paper deals with the development of this simulation platform, based on Generalized Discrete Event Specification (G-DEVS) models and HLA (High Level Architecture) standard. The different partners components of the networked logistics enterprise are described. The proposed solution is applied to a freight transportation system and emulates the behaviour of the various components (RFID coupled to geolocation and mobile technology) required to optimize the products routing. The behaviour of the main components is G-DEVS formalized including the logistics supplier server, the smart product and the vehicle onboard device to interface the products with a centralized server. Delivery scenarios are then elaborated and simulated to check the behaviour and the intensity of communication network use between distributed G-DEVS models and other simulation components. The strength of the approach lies in the interoperability of the platform to simulate scenarios including discrete event models, real software and hardware devices all linked via an HLA connection. From these results, a discussion is given to validate or reject the conceptual choices about logistics components behaviour and their network bandwidth requirement regarding GSM, GPRS, Bluetooth and RFID networks theoretical capacities.

A Generalized Discrete Event System (G-DEVS) Flattened Simulation Structure: Application to High-Level Architecture (HLA) Compliant Simulation of Workflow

The objective of the paper is to specify a new flattened Generalized Discrete Event System simulation engine structure and the Workflow modeling and simulation environment embedding it. We express first the new flattened simulation structure and give the corresponding transformation functions. We analyze performance tests conducted on this new simulation structure to measure its efficiency. Then, having selected the essential concepts in the elaboration of the Workflow, we present a language of description to define the Workflow processes. Finally, we define a distributed Workflow Reference Model that interfaces components of the Workflow with respect to the High-Level Architecture standard. Today enterprises can take advantage of this platform in the context of networking where interoperability, flexibility, and efficiency are challenging concepts.

Short-Lived Ontology Approach for Agent/HLA Federated Enterprise Interoperability

This paper aims at proposing an implementation of the Federation oriented Enterprise Interoperability concept, using the rising notion of Short-Lived Ontology. We give first, a review of ongoing researches on Enterprise Interoperability. Then, we recall on Artificial Agent Concept and HLA Standard that appear to be adequate to support execution of the studied con-cept. Indeed, on the one hand Agent dialogue fits the concept of information exchange in a federated enterprise interoperability approach, on the other hand the HLA standard, initially designed for military M&S purpose, can be transposed for enterprise interoperability at the implementation level, reusing the years of experiences in distributed systems. From these post-ulates, we propose the first Agent/HLA framework Short-Lived Ontology based to implement distributed enterprise models from the conceptual level of federated enterprise interoperability approach.

Improving the lookahead computation in G-DEVS/HLA environment

In this paper, we present an improvement to evaluate the HLA lookahead for distributed DEVS/G-DEVS models in a HLA-compliant environment. The models considered in this distributed simulation have state lifetimes functions of several state variables. We use the graph theory Dijkstra search to compute the different values of the state variables and a mathematical function analysis to determine the lookahead for the model states. We illustrate on an example how this solution extends the range of DEVS/G-DEVS models that can be involved into distributed simulations.

Developing a web-enabled HLA federate based on portico RTI

This paper presents an approach to implement distributed simulation software to test, validate and improve information exchange between enterprises. The approach assumes some of the recently released HLA Evolved standard web service requirements. The implementation is based on improving the open source poRTIco HLA RTI tool. The paper mainly focuses on the presentation of the HLA web-enabled federate proposed to fulfill the web service needs of the brand new HLA 1516-2010 standard. The idea is that a federate is being connected to an HLA federation based on previous HLA standards version (1516- 2000 or 1.3) and, in parallel, to other federates outside the LAN federation via the WAN. This approach intends to improve federate components interoperability and agility in a heterogeneous, distributed and dynamic context. To achieve that goal, time management mechanisms have been developed. The concept is validated through distributed simulation of a car selling enterprise modeling test case.