Using virtual reality for requirements validation

Failures of high consequence systems are intolerable. Studies have shown that a significant percentage of safety problems can be traced back to errors in the specification. An important problem that arises during validation is how to include a domain expert in this process. Although the domain experts have exclusive knowledge about the system operation, they may not understand formalisms used for system specification.;Essential type of evidence of the correctness of the formalization process must be provided by human-based calculation. Human calculation can be significantly amplified by shifting from symbolic representation to graphical representations. This, in turn, provides an environment for validation of the system model.;We have developed a virtual environment model for the Production Cell robotic system, which runs in an ImmersaDesk Virtual Reality environment. Although it introduces higher cost in the requirements formalization phase, this approach can be very beneficial in the development of high consequence systems

A Framework To Model Complex Systems Via Distributed Simulation: A Case Study Of The Virtual Test Bed Simulation System Using the High Level Architecture

As the size, complexity, and functionality of systems we need to model and simulate con-tinue to increase, benefits such as interoperability and reusability enabled by distributed discrete-event simulation are becoming extremely important in many disciplines, not only military but also many engineering disciplines such as distributed manufacturing, supply chain management, and enterprise engineering, etc. In this dissertation we propose a distributed simulation framework for the development of modeling and the simulation of complex systems. The framework is based on the interoperability of a simulation system enabled by distributed simulation and the gateways which enable Com-mercial Off-the-Shelf (COTS) simulation packages to interconnect to the distributed simulation engine. In the case study of modeling Virtual Test Bed (VTB), the framework has been designed as a distributed simulation to facilitate the integrated execution of different simulations, (shuttle process model, Monte Carlo model, Delay and Scrub Model) each of which is addressing differ-ent mission components as well as other non-simulation applications (Weather Expert System and Virtual Range). Although these models were developed independently and at various times, the original purposes have been seamlessly integrated, and interact with each other through Run-time Infrastructure (RTI) to simulate shuttle launch related processes. This study found that with the framework the defining properties of complex systems - interaction and emergence are realized and that the software life cycle models (including the spiral model and prototyping) can be used as metaphors to manage the complexity of modeling and simulation of the system. The system of systems (a complex system is intrinsically a system of systems ) continuously evolves to accomplish its goals, during the evolution subsystems co-ordinate with one another and adapt with environmental factors such as policies, requirements, and objectives. In the case study we first demonstrate how the legacy models developed in COTS simulation languages/packages and non-simulation tools can be integrated to address a compli-cated system of systems. We then describe the techniques that can be used to display the state of remote federates in a local federate in the High Level Architecture (HLA) based distributed simulation using COTS simulation packages

Insight generation in simulation studies: an empirical exploration

This thesis presents an empirical research that aims to explore insight generation in discrete-event simulation (DES) studies. It is often claimed that simulation is useful for generating insights. There is, however, almost no empirical evidence to support this claim. The factors of a simulation intervention that affect the occurrence of insight are not clear. A specific claim is that watching the animated display of a simulation model is more helpful in making better decisions than relying on the statistical outcomes generated from simulation runs; but again, there is very limited evidence to support this. To address this dearth of evidence, two studies are implemented: a quantitative and a qualitative study. In the former, a laboratory-based experimental study is used, where undergraduate students were placed in three separate groups and given a task to solve using a model with only animation, a model with only statistical results, or using no model at all. In the qualitative study, semi-structured interviews with simulation consultants were carried out, where participants were requested to account examples of projects in which clients change their problem understanding and generate more effective ideas. The two separated parts of the study found different types of evidence to support that simulation generates insight. The experimental study suggests that insights are generated more rapidly from statistical results than the use of animation. Research outcomes from the interviews include descriptions of: the phase of a simulation study where insight emerges; the role of different methods applied and means used in discovering and overcoming discontinuity in thinking (for instance, the role of consultant s influence in problem understanding); how some factors of a simulation intervention are associated with the processes of uncovering and overcoming discontinuity in thinking (for example, the role of clients team in the selection of methods used to communicate results); and the role of the model and consultant in generating new ideas. This thesis contributes to the limited existing literature by providing a more in depth understanding of insight in the context of simulation and empirical evidence on the insight-enabling benefits of simulation based on an operational definition. The findings of the study provide new insights into the factors of simulation that support fast and creative problem solving

User interfaces and discrete event simulation models.

A user interface is critical to the success of any computer-based system. Numerous studies have shown that interface design has a significant influence on factors such as learning time, performance speed, error rates, and user satisfaction. Computer-based simulation modelling is one of the domains that is particularly demanding in terms of user interfaces. It is also an area that often pioneers new technologies that are not necessarily previously researched in terms of human-computer interaction. The dissertation describes research into user interfaces for discrete event simulation. Issues that influence the 'usability' of such systems are examined. Several representative systems were investigated in order to generate some general assumptions with respect to those characteristics of user interfaces employed in simulation systems. A case study was carried out to gain practical experience and to identify possible problems that can be encountered in user interface development. There is a need for simulation systems that can support the developments of simulation models in many domains, which are not supported by contemporary simulation software. Many user interface deficiencies are discovered and reported. On the basis of findings in this research, proposals are made on how user interfaces for simulation systems can be enhanced to match better the needs specific to the domain of simulation modelling, and on how better to support users in simulation model developments. Such improvements in user interfaces that better support users in simulation model developments could achieve a reduction in the amount of time needed to learn simulation systems, support retention of learned concepts over time, reduce the number of errors during interaction, reduce the amount of time and effort needed for model development, and provide greater user satisfaction