Simon J. E. Taylor

Simulation model reuse: definitions, benefits and obstacles

Abstract The term ‘simulation model reuse’ can be taken to mean various things from the reuse of small portions of code, through component reuse, to the reuse of complete models. On a more abstract level, component design, model design and modelling knowledge are prime candidates for reuse. The reuse of simulation models is especially appealing, based on the intuitive argument that it should reduce the time and cost for model development. In a discussion with four simulation modelling experts, however, a number of issues were raised that mean these benefits may not be obtainable. These issues include the motivation to develop reusable models, the validity and credibility of models to be reused, and the cost and time for familiarisation. An alternative simulation methodology was proposed, that may lend itself better to model reuse.

Profiling Literature in Healthcare Simulation

The publications that relate to the application of simulation to healthcare have steadily increased over the years. These publications are scattered amongst various journals that belong to several subject categories, including operational research, health economics and pharmacokinetics. The simulation techniques that are applied to the study of healthcare problems are also various. The aim of this study, therefore, is to review healthcare simulation literature that have been published between 1970 and 2007 in high-quality journals belonging to various subject categories and that report on the application of four simulation techniques, namely, Monte Carlo simulation, discrete-event simulation, system dynamics and agent-based simulation. Arguably, journal impact factor is fundamental in assessing the quality of publications. Thus, the 201 publications selected for review have been queried from the ISI Web of Science® bibliographic database of high-impact research journals. Through a review of healthcare simulation literature the following three objectives have been realized: (a) papers have been categorized under the different simulation techniques, and the healthcare problems that each technique is employed to investigate are identified; (b) variables such as authors, article citations, etc., within our dataset of healthcare papers have been profiled; (c) turning point (strategically important) papers and authors have been identified through co-citation analysis of references cited by the papers in our dataset. The above objectives have been realized by devising and then employing a methodology for profiling literature. It is expected that this review paper will help the readers gain a broader understanding of research in healthcare simulation.

Facilitating the Analysis of a UK National Blood Service Supply Chain Using Distributed Simulation

In an attempt to investigate blood unit ordering policies, researchers have created a discrete-event model of the UK National Blood Service (NBS) supply chain in the Southampton area of the UK. The model has been created using Simul8, a commercial off-the-shelf (COTS) discrete-event simulation package (CSP). However, as more hospitals were added to the model, it was discovered that the length of time needed to perform a single simulation severely increased. It has been claimed that distributed simulation, a technique that uses the resources of many computers to execute a simulation model, can reduce simulation runtime. Further, an emerging standardized approach exists that supports distributed simulation with CSPs. These CSP Interoperability (CSPI) standards are compatible with the IEEE 1516 standard, the High Level Architecture (HLA), the de facto interoperability standard for distributed simulation. To investigate if distributed simulation can reduce the execution time of NBS supply chain simulation, this paper presents experiences of creating a distributed version of the CSP Simul8 according to the CSPI/HLA standards. It shows that the distributed version of the simulation does indeed run faster when the model reaches a certain size. Further, we argue that understanding the relationship of model features is key to performance. This is illustrated by experimentation with two different protocols implementations (using Time Advance Request (TAR) and Next Event Request (NER)). Our contribution is therefore the demonstration that distributed simulation is a useful technique in the timely execution of supply chains of this type and that careful analysis of model features can further increase performance.

Enhancing simulation education with intelligent tutoring systems

The demand for education in the area of simulation is in the increase. This paper describes how education in the field of simulation can take advantage of the virtues of intelligent tutoring with respect to enhancing the educational process. For this purpose, this paper gives an overview of what constitutes the objectives and the content of a comprehensive course in discrete event simulation. The architecture of an intelligent tutoring system is presented and it is discussed how these sophisticated learning aids offer individualised student guidance and support within a learning environment. The paper then introduces a prototype intelligent tutoring system, the simulation tutor, and suggests how the system might be developed to enhance education in simulation.

Integrating heterogeneous distributed COTS discrete-event simulation packages: an emerging standards-based approach

This paper reports on the progress made toward the emergence of standards to support the integration of heterogeneous discrete-event simulations (DESs) created in specialist support tools called commercial-off-the-shelf (COTS) discrete-event simulation packages (CSPs). The general standard for heterogeneous integration in this area has been developed from research in distributed simulation and is the IEEE 1516 standard The High Level Architecture (HLA). However, the specific needs of heterogeneous CSP integration require that the HLA is augmented by additional complementary standards. These are the suite of CSP interoperability (CSPI) standards being developed under the Simulation Interoperability Standards Organization (SISO-http://www.sisostds.org) by the CSPI Product Development Group (CSPI-PDG). The suite consists of several interoperability reference models (IRMs) that outline different integration needs of CSPI, interoperability frameworks (IFs) that define the HLA-based solution to each IRM, appropriate data exchange representations to specify the data exchanged in an IF, and benchmarks termed CSP emulators (CSPEs). This paper contributes to the development of the Type I IF that is intended to represent the HLA-based solution to the problem outlined by the Type I IRM (asynchronous entity passing) by developing the entity transfer specification (ETS) data exchange representation. The use of the ETS in an illustrative case study implemented using a prototype CSPE is shown. This case study also allows us to highlight the importance of event granularity and lookahead in the performance and development of the Type I IF, and to discuss possible methods to automate the capture of appropriate values of lookahead.

So where to next? A survey of the future for discrete-event simulation

Discrete-event simulation (DES) has been with us for around 50 years. During this time, the field has seen significant progress as witnessed by the plethora of software packages and reported applications. But what of the future? Where does the field of DES need to go in the next 10 years? As part of this first issue of the Journal of Simulation (JOS), the Editors-in-Chief have surveyed the Editorial Board for their answers to this question. In particular, those surveyed were asked to comment on four areas: simulation technology, simulation experimentation and analysis, simulation applications and simulation practice. The findings from the 13 responses obtained are summarized under these same headings in the JOS 2006 Survey.

Research and commercial opportunities in Web-Based Simulation

Abstract In a few short years, Web-Based Simulation has exhibited explosive growth in the simulation research community. This paper which grew out of a panel discussion at the 2000 WEBSIM Conference, briefly reviews the development of this research area and considers future opportunities, both on the research and commercial sides. On the research side, the area is maturing, but still quite active. Efforts to expanded Web-Based Simulation to include new capabilities beyond those found in conventional simulation technology or provide interoperation with other information processing technology are particularly promising. On the commercial side, a critical mass of research knowledge is now available. However, some catalyst is needed to produce any substantial movement of simulation vendors toward Web-Based Simulation. This could happen quickly under a couple of scenarios: A small simulation vendor focused on Web-Based Simulation could begin to claim significant market share. Alternatively, the development of a “killer-app” to demonstrate a clear advantage to Web-Based Simulation could make this shift happen very quickly.

Simulation modelling is 50! Do we need a reality check?

Simulation modelling is a fascinating research field. The techniques and tools of simulation modelling have been used to research and investigate the behaviour of various systems in a wide range of areas such as commerce, computer networks, defence, health, manufacturing and transportation. Indeed, the study of the use of these techniques and tools, and the development of new forms of these, are a rich source of research in their own right. Simulation modelling is about to reach the 50th anniversary of the development of GSP (General Simulation Program), the first simulation modelling language (Tocher and Owen, 1960). There have been several historical accounts of simulation modelling research. To complement these, we have performed a review of the recent history of simulation modelling. This study targeted three leading journals dedicated to this field. These are the ACM Transactions of Modeling and Computer Simulation, Simulation: Transactions of The Society for Modeling and Simulation International and Simulation Modelling Practice and Theory (formerly Simulation Practice and Theory). The study covered the first 6 years of this century (2000–2005) and included 576 papers. The key observation of this work was the relative lack of ‘real world’ involvement in simulation modelling research and an even greater lack of evidence of ‘real world’ benefit, arguably very alarming outcomes for an applied field. To further investigate this observation two additional surveys were carried out, one to study if real world papers appeared in the more widely known OR/MS literature (837 papers in 12 journals) and one to study if such papers appeared in Manufacturing and Logistics, an application area closely associated with simulation modelling (1077 papers in 10 journals). The results of these surveys confirmed our observations. We ask if this is the natural evolution of a field that has existed for half a century or an indication of a worrying problem? This paper reports on our findings and discusses whether or not simulation modelling research urgently needs to face a ‘reality check.’

Distributed supply chain simulation in GRIDS

Amongst the majority of work done in supply chain simulation, papers have emerged that examine the area of model distribution. The executions of simulations on distributed hosts as a coupled model require both coordination and facilitating infrastructure. A distributed environment, the Generic Runtime Infrastructure for Distributed Simulation (GRIDS) is suggested to provide the bonding requirements for such a model. The advantages of transparently connecting the distributed components of a supply chain simulation allow the construction of a conceptual simulation while releasing the modeler from the complexities of the underlying network. The infrastructure presented demonstrates scalability without losing flexibility for future extensions based on open industry standards.

GRIDS-SCF: An infrastructure for distributed supply chain simulation

Within the context of supply chain simulation, this paper introduces the generic runtime infrastructure for distributed simulation as a novel infrastructure for distributed supply chain simulation that promotes user transparency and extensible service provision. These are discussed with regard to a distributed simulation of a supply chain model (federation) GRIDS-SCF and a case study on supply chain simulation from the automotive industry. The main aim of this work is to provide industry with a business benefit from distributed simulation by making it possible to connect and reuse previously developed models in a supply chain while minimizing technological intervention (additional technological skills required) with the end user simulationist. It is suggested that this approach may pave the way for distributed supply chain simulation that emphasizes simulation methodology rather than technology.