Decision development in facilitated modelling workshops

While the facilitated modelling literature recognises the importance of the group process within facilitated modelling workshops, published empirical research rarely examines their dynamic nature. In this paper, we address this gap in the literature in two ways. First, we propose to locate facilitated modelling workshops as the main focus of investigation, and adopt decision development as the analytical lens. Second, we provide guidance regarding how to implement a research strategy that is informed by such a focus. We start by mapping the different conceptualisations of decision development that seem embedded within the facilitated modelling tradition, and contrast them with theoretical models from the group communication field. Our analysis identifies a number of potentially useful areas for the study of facilitated modelling workshops from a decision development perspective, and articulates a number tentative research questions and testable propositions amenable to empirical research. Central to our proposal are research methods for the study of dynamic group processes. We thus discuss the steps required to extract group process data from facilitated modelling workshops that are usable and open to analysis. This includes a review of issues regarding research design, coding scheme development, data coding and choice of analytical techniques. Finally, we offer conclusions and briefly discuss some feasibility issues related to the implementation of our proposal.     

Why modelling and model use matter

When OR/MS analysts develop a model, how are they intending this model to be used? There are many different ways in which OR/MS models may be classified and one important categorisation is the intended use of the model. Some models are intended for routine use on a frequent basis, with little or no human intervention. Others form part of human decision process and provide support to that process. Considering model validation, data requirements, added value and possible pitfalls leads to a theory of model use based on four categories: decision automation, routine decision support, investigation and improvement, and generating insights for debate. A pilot investigation in an OR/MS group demonstrates that this categorisation could provide the basis for empirical research into a theory of model use in operational research. A theory of model use would be of value to academics, who could prioritise their work, and to practitioners, who could place their own work in a broader landscape.     

The use of a modified Petrov-Galerkin method for gas-sold reaction modelling

A new numerical technique for simulating gas-solid reactionsincluding diffusion through the reactant and product layers,reaction on the shrinking surface and internal reaction is presented.Some transformations are introduced, and this model can be reducedto dimensionless form including a selfadjoint, singularly perturbed,two-point boundary-valve problem and two initial-value problems.A combination of the Petrov-Galerkin finite element method andpredictor-corrector method is applied to solve the problem.It is shown that the shrinking-core model including both surfacereaction and product layer diffusion can arise for low initialrelative permeability and the diffusion-controlled shrinking-coremodel occurs when the product layer diffusional resistance islarge relative to the surface reaction. This method is simpleand there is no limit on the range of the parameters. Computedresults are numerically evaluated for comparison with resultsof previous authors.     

Expert and novice facilitated modelling: A case of a Viable System Model workshop in a local food network

This paper provides an empirical study based on action research in which expert and novice facilitators in facilitated modelling workshops are compared. There is limited empirical research analysing the differences between expert and novice facilitators. Aiming to address this gap we study the behaviour of one expert and two novice facilitators during a Viable System Model workshop. The findings suggest common facilitation patterns in the behaviour of experts and novices. This contrasts literature claiming that experts and novices behave and use their available knowledge differently, and empirically supports the claim that facilitation skills can be taught to participants to enable them to self-facilitate workshops. Differences were also found, which led to the introduction of a new dimension—‘internal versus external’ facilitation. The implications of our findings for effective training and facilitation strategies in contexts in which external, expert facilitation is not always possible are also discussed, and limitations of this study are provided.     

On the use of multi-state multi-census techniques for modelling the survival of elderly people in institutional long-term care

^** Corresponding author. Email: chausst{at}wmin.ac.uk A good estimate of the length of stay (LOS) of elderly peoplein institutional long-term care (ILTC) is essential to bothcare providers (care home owners) and purchasers (local authoritiesin the UK) in order to forecast their resource availabilityand future requirements. Existing methods usually rely on cohortdata, which needs to be collected on a continuous basis forseveral years and are often not available electronically. Inthis paper we develop an approach based on multi-census datato fit a Markov model in continuous-time for the LOS of elderlypeople in ILTC (residential and nursing care). We use 3 yearplacement data provided by London Borough of Merton Social Servicesto compare the estimates of the model parameters obtained usingmulti-census data with those derived from cohort data, henceto validate the multi-census approach in this context. The implicationsof the proposed multi-census approach and its advantages inthe context of long-term care planning are discussed.     

Towards governance on noise between municipality and terminal operator by the use of simulation modelling

The development of multimodal transport terminals in urban areas generates various serious environmental problems. The available tools for the analyses of the use of such terminals offer insufficient support for decision-making on the location and design of these terminals from the sustainability perspective. New approaches are needed. This article contributes to satisfy this need, triggered by the planning of a new Barge Terminal in the Dutch city of Tilburg (BTT). Presently, the existing terminal in Tilburg is operating near full capacity and the construction of a new terminal is considered the best strategy to cope with steady growth. The main question concerns the optimal design of the new barge terminal to offer a high operational performance, however without exceeding the environmental quality standards, in particular noise. The article presents a simulation approach to assist in the process of finding a balance between the operational performance and the noise effects of alternative designs of the new terminal.     

Optimal and feedback strategies for managing multicohort populations

A Beverton and Holt type linear cohort dynamics model is integrated and combined with a nonlinear stock-recruitment relationship to obtain a discrete-time multicohort harvesting model. Assuming that each age class is individually controllable, it is shown, subject to certain assumptions, that the optimal harvesting strategy is to drive the population to the maximum sustainable yield solution in one time step. In most fisheries, this controllability assumption is not met and harvesting is agewise nonselective. In this case, it may be preferable to implement a harvesting policy based on suboptimal constant effort or stock level feedback strategies, rather than implement a more complicated optimal policy. This question is addressed through numerical studies on the management of an anchovy fishery.Dedicated to G. LeitmannThe author would like to thank M. Mangel, W. Reed, P. Sullivan, and G. Swartzman for commenting on a draft of this paper.     

Wavelets and splines for modelling the earth's magnetic field

At the present time there is an unprecedented opportunity to use satellite magnetometer data, as for example Oersted and CHAMP records, to improve our knowledge of the Earth's magnetic field and its sources. These measurements contain contributions from the main magnetic field of the Earth, the crustal field as well as contributions coming from different exterior (ionospheric and magnetospheric) sources. For the mathematical analysis of the data it is critical to have in hand appropriate tools which separate these sources and which are able to analyze the different contributions independently. We present in this talk an approach in terms of (spherical) scalar and vectorial scaling functions and wavelets to handle these problems. Examples include crustal field modelling and reconstruction of ionospheric currents. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dynamic modelling and input-energy comparison for the elevator system

The elevator system driven by a permanent magnet synchronous motor (PMSM) is studied in this paper. The mathematical model of the elevator system includes the electrical and mechanical equations, and the dimensionless forms are derived for the purpose of practicable upward and downward movement. In this paper, the trapezoidal, cycloidal, five-degree (5-D) and seven-degree (7-D) polynomial and industry trajectories are designed and compared numerically in various motion and the absolute input energies. From numerical simulations, it is found that the trapezoidal trajectory consumes the minimum energy; the 7-D polynomial trajectory consumes the maximum one. The less end-point constraints are required, the less energy is consumed. Finally, the proposed sliding mode controller (SMC) is employed to demonstrate the robustness and well tracking control performance numerically.     

Ecological-economic modelling for the sustainable management of biodiversity

Terrestrial and marine biodiversity provides the basis for both ecosystems functioning and numerous commodities or services that underpin human well-being. From several decades, alarming trends have been reported worldwide for both biodiversity and ecosystem services. Therefore the sustainable management of biodiversity requires a double viewpoint balancing ecological conservation with the welfare of human societies. Understanding the underlying trade-offs, synergies and interactions imposes the development of interdisciplinary researches and methods. In that respect, bio-economic or ecological economic modeling is likely to play a major role. The present paper intends to elicit the key features, strengths and challenges of bio-economic approaches especially in mathematical and computational terms. It first recall the main bio-economic methods, models and decisional instruments used in these types of analyses. Then the paper shows to what extent bio-economic sustainability lies between equilibrium, viability and optimality mathematical frameworks. It ends up by identifying new major challenges among which the operationalization of ecosystem based management, the precautionary principle and the implementation of governance are especially important.     

Challenges for mathematical and statistical modelling for metrology

There are challenges in disseminating information concerning mathematical and statistical modelling for metrology. We specify these challenges and consider ways they are being met. In addition to journal papers, the value of supporting software and other aspects are indicated. Relevant work in the UK Software Support for Metrology programme is outlined. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mathemetical modelling for the control and prevention of animal production diseases

A computerized information-retrieval system for slaughterhouse-condemnationand meteorological data was established in Northern Irelandin 1986. The system has been used to study the epidemiologyof economically important diseases of cattle, sheep, and pigswhich occur during the production period. The system containsinformation on condemnations recorded in all abattoirs in NorthernIreland since 1969 and a concurrent database of all major prevailingweather variables. The software available on the system enablescomplex time-series analyses of the integrated database on aroutine interactive basis. The computerized system has been used to highlight, to the agriculturalindustry, the continued importance of the control and preventionof a number of animal production diseases. In this paper, wedescribe the formulation of a new mathematical model which accuratelyforecasts the annual prevalence of fasciolosis in cattle. Theforecasts form the basis of specific veterinary advice on thestrategic use of effective control measures.     

Hybrid coordinate approach for the modelling and simulation of multibody systems

The main goal of the present work is to provide an add-on scheme for the formulation of multibody dynamics, based on natural coordinates, in regard to ideally balanced rigid bodies with high rotational spin, e.g. gyroscopes. The underlying aim of this approach is to achieve higher numerical accuracy whenever the preferred axis of rotation coincides with the balanced main axis of the body. This will be achieved by seperating the spin of the balanced rigid body along the denoted axis as an additional angular coordinate, whereas the other rotations will be covered by a carried frame, parameterized via natural coordinates. At the same time the carried frame provides a link to the existing modelling framework in terms of natural coordinates, enabling a straightforward implementation into existing multibody systems (e.g. rotary crane [2]). (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The use of historical control information in modelling dose response relationships in carcinogenesis

An empirical Bayes approach is proposed as a means of utilizing historical control information in modelling the relationship between the level of exposure to the test agent and the rate of tumour occurrence in carcinogenicity bioassays. Using a simple two-parameter linear logistic model, it is shown that when the historical control response rates are tightly clustered around the response rate in the concurrent control group, the empirical Bayes estimator can be considerably more precise than the usual maximum likelihood estimator ignoring the historical data. Efficiency gains were also noted with respect to estimates of quantiles of the dose response curve such as the ED₁₀. With a three-parameter logistic model in which spontaneously occurring lesions are assumed to be stochastically independent of those caused by the test agent, only modest gains in efficiency using historical control data were observed.     

Improved optimization modelling for the closest string and related problems

We present a new integer linear programming model for the closest string problem. This model requires considerably less variables and constraints than the popular binary linear programming model used for this purpose. Due to the reduced size it is easier to handle rounding errors when an LP relaxation technique is used to solve the problem.