Saikou Y. Diallo

Composable M&S Web Services for Net-Centric Applications

Service-oriented architectures promise easier integration of functionality in the form of web services into operational systems than is the case with interface-driven system-oriented approaches. Although the Extensible Markup Language (XML) enables a new level of interoperability among heterogeneous systems, XML alone does not solve all interoperability problems users contend with when integrating services into operational systems. To manage the basic challenges of service interoperation, we developed the Levels of Conceptual Interoperability Model (LCIM) to enable a layered approach and gradual solution improvements. Furthermore, we developed methods of model-based data engineering (MBDE) for semantically consistent service integration as a first step. These methods have been applied in the U.S. in collaboration with industry resulting in proofs of concepts. The results are directly applicable in a net-centric and net-enabled environment.

Reference modelling in support of M&S—foundations and applications

Whether by design or by practice, systems engineering (SE) processes are used more and more often in Modeling and Simulation (M&S). While the two disciplines are very close, there are some differences that must be taken into account in order to successfully reuse practices from one community to another. In this paper, we introduce the M&S System Development Framework (MS-SDF) that unifies SE and M&S processes. The MS-SDF comprises the SE processes of requirements capture, conceptual modelling, and verification and validation (V&V), and extends them to M&S. We use model theory as a deductive apparatus in order to develop the MS-SDF. We discuss the benefits of the MS-SDF especially in the selection between federation development and multi-model approaches and the design of composable models and simulations. Lastly, a real life application example of the framework is provided.

Implied ontological representation within the levels of conceptual interoperability model

The Levels of Conceptual Interoperability Model LCIM has been developed to provide both a metric of the degree of conceptual representation that exists between interoperating systems and also as a guide showing what is necessary to accommodate a targeted degree of conceptual representation between systems. The model was originally developed to support the interoperability of simulation systems, but has been shown to be useful for other domain areas. The model is stratified into seven general levels, and these are introduced and defined. Implied within the model is that the information and processes of one system should be described and that description is then made available to another system. This description of information and processes can take many forms, but is generally an ontological representation. The components of an ontological representation are defined in form and also as elements for the various layers of the LCIM.

You Are What You Tweet: Connecting the Geographic Variation in America’s Obesity Rate to Twitter Content

We conduct a detailed investigation of the relationship among the obesity rate of urban areas and expressions of happiness, diet and physical activity on social media. We do so by analyzing a massive, geo-tagged data set comprising over 200 million words generated over the course of 2012 and 2013 on the social network service Twitter. Among many results, we show that areas with lower obesity rates: (1) have happier tweets and frequently discuss (2) food, particularly fruits and vegetables, and (3) physical activities of any intensity. Additionally, we provide evidence that each of these results offer different and unique insight into the variation of the obesity rate in urban areas within the United States. Our work shows how the contents of social media may potentially be used to estimate real-time, population-scale measures of factors related to obesity.

Supporting Network Enabled Capability by extending the Levels of Conceptual Interoperability Model to an interoperability maturity model

The North Atlantic Treaty Organization (NATO) Network Enabled Capability (NNEC) addresses technical and cognitive abilities of NATO requiring technical and operational interoperability standards and targets for adaptation. Net-enabled Modeling and Simulation (M&S) can support in all life cycle phases. The paper evaluates the contribution of four example technical activities of NATO conducted by different bodies of the Research and Technology Organization: net-enabled M&S by the Modeling and Simulation Group, semantic interoperability by the Information Systems Technology panel, new command and control concepts by the System Analysis & Studies panel, and human factors for NNEC by the Human Factors & Medicine panel. The results request a framework that included technical and operational aspects as well. The technical challenges can be supported by the Levels of Conceptual Interoperability Model, which is extended to an Interoperability Maturity Model. The operational challenges can be supported by the NNEC Command and Control Maturity Model. Both models are aligned to provide the necessary support to address NATO’s technical and cognitive abilities by M&S services.

A Layered Approach to Composition and Interoperation in Complex Systems

This chapter introduces three engineering methods to support the evaluation of composition and interoperation in complex systems. Data engineering deals with conceptualization of entities and their relations. Process engineering deals with conceptualization of functions and behaviors. Constraint engineering deals with valid solution spaces for data and processes. It is shown that all three aspects must be considered and supported by a solution. The Levels of Conceptual Interoperability Model is used as the basis for the engineering methods. Several current solutions to support complex systems in knowledge-based environments are evaluated and compared.

A Conceptual Modeling Method for Critical Infrastructure Modeling

Conceptual Modeling often is perceived as a way of introducing the process of modeling a system, by concentrating on a reduced appreciation of that system, with a necessary reduction in the number of affecting variables and relations making up the model. As an alternative to this approach, rather than reduce the number of variables and relations, it has been found to be useful to include as many as possible variables and relations (resulting from a functional decomposition of a class of like systems) in a Potential Model (which represents the potential of all specific instances of the class of like systems), and then to move towards a Specific Model by applying contextual and situational values to the appropriate variables and relations that apply to the actual case. In so doing, the necessary reduction in variables and relations in moving from Potential Model to Specific Model allows the conceptual model to lead to further steps in the modeling process, ensuring that all relevance to the class of system is retained. This technique has been applied to a critical infrastructure modeling project, with both the method and results being presented here.

Mathematical models towards self-organizing formal federation languages based on conceptual models of information exchange capabilities

Conceptual models capture information that is crucial for composability of legacy solutions that is not formally captured in the derived technical artifacts. It is necessary to make this information available for the selection (or elimination) of available solutions, their orchestration, and their execution. Current standards barely address this class of problems. The approach presented in this paper is the first step towards self-organizing federation languages. The system interfaces are described in form of exchangeable data. The context of information exchange (syntax, semantics, and pragmatics) is captured as metadata. These metadata are used to identify the elements of a formal federation language that links model composability and simulation interoperability based on conceptual model elements. The paper describes the formal process of selection, orchestration, and execution and the underlying mathematics for the information exchange specifications that bridge conceptual and engineering levels of the federation process.

Towards a theory of multi-method m&s approach: part III

This paper is the first from a series of papers that aim to develop a theory of multi-method M&S approach. The aim of this paper is to develop ontological basis for multi-method M&S approach. The first part of this paper discusses terms related to the use of more than a single modeling & simulation (M&S) method. This is to show the ontological ambiguity currently present within the M&S field in the context of using more than a single method. Next section provides the philosophical stance of the authors about the main terms in order to provide clarification and context of the term multi-method M&S approach. The last section takes these previous concepts and proposes a set of definitions relevant to a multi-method M&S approach, including its parent and derivative terms.

Using a formal approach to simulation interoperability to specify languages for ambassador agents

Ambassador agents represent simulation services that are candidates to contribute to the solution of a problem. They need to know and express enough about the simulations to negotiate with other ambassador agents if the represented simulation systems can be composed to contribute to the solution. A formal approach to simulation interoperability based on set theory and date modeling theory was developed. The formal model of data in M&S capturing possible representations of real or imagined things in the world including definitions for existential and transformational dependencies is presented. Existential dependencies capture the relationships within a model while transformational dependencies capture the relationships between interactions with a model. These definitions are used to formally specify interoperation, the ability to exchange information, as a necessary condition for interoperability. The elements needed for a language needed for ambassador agents are derived using the formal approach to interoperability.