A toolkit of designs for mixing discrete event simulation and system dynamics

In recent years there has been significant interest in multimethodology and the mixing of OR/MS methods, including Discrete Event Simulation (DES) with System Dynamics (SD). Several examples of mixing DES and SD are described in the literature but there is no overarching framework which characterises the spectrum of options available to modellers. This paper draws on a sample of published case studies, in conjunction with the theoretical literature on mixing methods, to propose a toolkit of designs for mixing DES and SD which can be implemented as a set of questions which a modeller should ask in order to guide the choice of design and inform the associated project methodology. The impetus for this work was the perceived need to transfer insight from reported practice in order to formalise how the two methods can be and have been mixed

Models of Models: The Symbiotic Relationship between Models and Wargames

Military planning uses wargames to model the processes and decisions of an operation. As these operations become increasingly complex, the wargames similarly become more complex. Complex wargames are difficult to design and execute. As such, computer-based modeling and simulation can aid the wargame development, ensuring smooth execution. In particular, computer-based modeling and simulation can develop and validate the processes, determine initial conditions, evaluate the rules, and aid in validation. In turn, the wargame can provide useful data that can be fed into detailed models that can provide quantitative analysis to decision-makers

Hybrid Simulation Design and Implementation

Hybrid Simulation in the Operational Research (OR) domain can be defined as the combination of two or more of the simulation methods of discrete-event simulation, agent-based simulation and system dynamics. This article examines how this combination might be achieved by reviewing the characteristics of the simulation methods, considering design view options and taking into account software tools for implementation. The purpose is to provide guidance on how hybrid simulation configurations can be designed and implemented

A study of the application of simulation software for business processes

This paper reports on the experiences of using two popular business process simulation (BPS) software packages. BPS is a technique, which assists companies in mimicking their everyday operations to find ways in which to improve and develop them in order to achieve either productivity, financial, or risk-free gains. There are many computer packages available on the market, and it is important to have an idea of the type of software that can promote these benefits further. The two software packages investigated in this study are Witness by the Lanner Group and Simul8 by the Simul8 Corporation. These packages are used by organisations as management tools to optimise their internal practices. A practical evaluation of both packages has been undertaken, using the model building of case studies in both Witness and Simul8. Comparisons were made, with a number of conclusions and recommendations, and the advantages and disadvantages of each package are given. This study is different from other investigations as it focuses on evaluating the user experience rather than a traditional comparison of the statistical output of the reference models

A study of continuous modelling using simulation software for business processes

In this paper, two business process simulation (BPS) software tools have been evaluated and compared in terms of the user experience. BPS is a technique, which assists companies in mimicking their everyday operations to find ways in which to improve and develop them to achieve either productivity, financial or risk-free gains. There are many computer packages available on the market, and it is important to have an idea of the type of software that can promote these benefits further. The two software packages investigated in this study are Witness (the Lanner Group) and Simul8 (Simul8 Corporation). These packages are used by organisations as management tools to optimise their internal operations. A practical evaluation of both packages has been undertaken from the experience gained during the model building of a refinery case study. Comparisons were made with a number of conclusions and recommendations, and the advantages and disadvantages of each package are provided. This study is different from other investigations as it focuses on evaluating the user experience rather than a traditional comparison of the statistical output of the reference models and it also focuses on a continuous-time simulation

Including Generative Mechanisms in Project scheduling using Hybrid Simulation

Scheduling is central to the practice of project management and a topic of significant interest for the operations research and management science academic communities. However, a rigour-relevance gap has developed between the research and practice of scheduling that mirrors similar concerns current in management science. Closing this gap requires a more accommodative philosophy that can integrate both hard and soft factors in the construction of project schedules. This paper outlines one interpretation of how this can be achieved through the combination of discrete event simulation for schedule construction and system dynamics for variable resource productivity. An implementation was built in a readily available modelling environment and its scheduling capabilities tested. They compare well with published results for commercial project scheduling packages. The use of system dynamics in schedule construction allows for the inclusion of generative mechanisms, models that describe the process by which some observed phenomenon is produced. They are powerful tools for answering questions about why things happen the way they do, a type of question very relevant to practic

Interfaces between SD and ABM modules in a hybrid model

Modelers in various disciplines have applied system dynamics (SD) and agent-based models (ABM) to support decision-makers in managing complex adaptive systems. Combining these methods in a hybrid simulation offers an opportunity to overcome the challenges that modelers face using SD or ABM alone. It also provides a complementary view and rich insight into the problems that modelers investigate. Hence, this approach can offer solutions to a plethora of systems problems. One of the limitations of existing frameworks that guide the process of combining SD and ABM is the lack of detailed guidance describing how the two methods can interact and exchange information. This paper provides guidance for interfacing these simulation modeling methods in a hybrid simulation. In this guidance, we describe interface approaches to exchanging information for different types of information flow between SD and ABM

Ergonomists as designers: computational modelling and simulation of complex socio-technical systems

Contemporary ergonomics problems are increasing in scale, ambition, and complexity. Understanding and creating solutions for these multi-faceted, dynamic, and systemic problems challenges traditional methods. Computational modelling approaches can help address this methodological shortfall. We illustrate this potential by describing applications of computational modelling to: (1) teamworking within a multi-team engineering environment; (2) crowd behaviour in different transport terminals; and (3) performance of engineering supply chains. Our examples highlight the benefits and challenges for multi-disciplinary approaches to computational modelling, demonstrating the need for socio-technical design principles. Our experience highlights opportunities for ergonomists as designers and users of computational models, and the instrumental role that ergonomics can play in developing and enhancing complex socio-technical systems. Recognising the challenges inherent in designing computational models, we reflect on practical issues and lessons learned so that computational modelling and simulation can become a standard and valuable technique in the ergonomists’ toolkit