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To provide a broader education for Operational Research PhD students in the UK, the Engineering and Physical Sciences Research Council funds the National Taught Course Centre for Operational Research (NATCOR). This is an initiative led by six UK universities and includes a one-week, residential simulation module taught for the first time in July 2009. We describe the background to NATCOR, summarize...
To graduate students accustomed to working with the numerical solution of partial differential equations using finite difference, finite elements, spectral methods, etc. where time generally progresses in evenly-spaced small intervals, switching paradigms to a discrete-event simulation environment is not only counterintuitive but is also difficult. The SimCenter at the University of Tennessee Chattanooga...
Simulation Modeling may have moved on from its early days as decision aiding and problem investigation. Large models of complex partially understood problems are being commissioned from model builders to enable investigations of the problem the model addresses. This paper raises the issues that need to be considered and thought about such situations.
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...
Agent-based simulation (ABS) is a recent modeling technique that is being widely used in modeling complex social systems. Forrester's System Dynamics (SD) is another longstanding technique for modeling social systems. Several classical models of systems, such as the Kermack-McKendrick model of epidemiology, the Lotka-Volterra equations for modeling predator-prey relationships, and the Bass model for...
Influence diagrams (IDs) are powerful tools for representing and solving complex decision making problems. This paper presents a simulation-based approach for solving decision making problems formulated by hybrid IDs, which involve both discrete and continuous decision and chance variables. In the proposed method, Monte-Carlo simulation is applied in both approximating the expected conditional utility...
Most residential-used electricity is nowadays generated at inefficient central power plants consuming environmental unfriendly resources like coal or natural gas. However, a trend towards distributed generation, distributed storage and demand side load management is seen to improve the energy efficiency. In order to analyze the impact and requirements of these emerging technologies and control methodologies,...
While eigenvalue elasticity analysis can offer insights into System Dynamics model behavior, such analysis is complicated, unwieldy and infeasible for larger models due to superlinear growth of the number of eigenvalue-parameter as the number of stocks rises. To overcome these difficulties, we develop a summary function elasticity analysis method, which aids in analyzing the impact of a parameter...
Models of dynamic systems are often constructed to improve system performance by identifying and modifying structures and parameters that drive system behavior. Once identified, these can be used to design and test policies for performance improvement. A preliminary step in developing policies is the identification of high leverage parameters and structures, the influential model sections that drive...
Coverage profiles help in visualizing what is modeled and how well it is modeled. Two DIME/PMESII models with initial validation results for their conceptual models are compared. The differences in their coverage profiles are examined and related to the differences in the purposes of the models. These results are used to draw conclusions about general models.
Validating social systems is not a trivial task. The paper outlines some of our past efforts in validating models of social systems with cognitively detailed agents. It also presents some of the challenges faced by us. A social system built primarily of cognitively detailed agents can provide multiple levels of correspondence, both at observable and abstract aggregated levels. Such a system can also...
The process of translating socio-cultural understanding and models into improved military effectiveness and expanded capabilities often seems sisyphean in its difficulty. This paper describes the clash of cultures that occurs when the deterministic mindset meets non-deterministic models and in which the desire for prediction can only be met by descriptive models. This disjuncture is exacerbated by...
This paper revisits a technique for determining structural equivalence between simulation models. Specifically brought under scrutiny are the restrictions for applying a rule that expands a compound event vertex when converting a simulation graph model (SGM) into an extended SGM. By checking for interdependencies of state variables within the vertex, one can ensure that the logical structure of the...
Constantly increasing complexity of organizational environments and changing demands of the stakeholders severely affects the strategic capabilities of organizations and reduces their decision making ability dramatically. Large-scale complex systems like energy grids, air-ground traffic control systems and logistics systems are designed in multi-actor environments and hence require various perspectives...
Smart environments are slowly but surely entering our everyday life. Their design provides many challenges. Not only heterogeneous devices acting and interacting in a dynamic environment but also intentions and activities of humans have to be taken into account. Diverse processes are responsible for achieving unobtrusive and pro-active user assistance. Those can be structured into a pipeline of perception,...
Conceptual modelling, one of the first stages in a simulation study, is about understanding the situation under study and deciding what and how to model. We argue that stakeholder involvement as part of conceptual modelling could lead to a more successful simulation study with better prospects for implementation. Our work is mainly applied in health care studies, which are characterized by many stakeholders...
The first phase of the conceptual modeling process is the acquisition of knowledge about the real world system. One issue in this phase is the need for clear communication, between the modeler, and experts on the system being examined. These domain experts may not be versed in modeling techniques or languages. Another issue is the potential benefit offered by the recording of the gathered knowledge,...
In recent years several simulation-based serious games have been developed for mastering new business concepts in operations management. This indicates the high potential of simulation use for pedagogical purposes. Unfortunately, this potential is hardly reflected in simulation methodology. We consider this issue by identifying alternative demands game use of simulation sets for model building and...
The usage of workflows to standardize processes, as well as to increase their efficiency and the quality of the results is a common technique. So far it has only been rarely applied in modeling and simulation. Herein we argue for employing this technique for the creation of various products in modeling and simulation. This includes the creation of models, simulations, modeling languages, and modeling...
Hierarchical component based modeling and simulation holds great promise, especially in terms of modeling efficiency and model reuse. However, in practice, the approach has not yet lived to its potential. After a diagnosis of this state of affairs, a solution inspired from model driven engineering is proposed. The basic architecture of the framework is explained, based on meta-models, models, and...
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