Qualitative Modelling Approach Research Articles

Alternative community structures in a kelp-urchin community: A qualitative modeling approach

Shifts in interaction patterns within a community may result from periodic disturbances and climate. The question arises as to the extent and significance of these shifting patterns. Using a novel approach to link qualitative mathematical models and field data, namely using the inverse matrix to identify the community matrix, we reconstructed community networks from kelp forests off the Oregon Coast. We simulated all ecologically plausible interactions among community members, selected the models whose outcomes match field observations, and identified highly frequent links to characterize the community network from a particular site. We tested all possible biologically reasonable community networks through qualitative simulations, selected those that matched patterns observed in the field, and further reduced the set of possibilities by retaining those that were stable. We found that a community can be represented by a set of alternative structures, or scenarios. From 11,943,936 simulated models, 0.23% matched the field observations; moreover, only 0.006%, or 748 models, were highly reliable in their predictions and met conditions for stability. Predator–prey interactions as well as non-predatory relationships were consistently found in most of the 748 models. These highly frequent connections were useful to characterize the community network in the study site. We suggest that alternative networks provide the community with a buffer to disturbance, allowing it to continuously reorganize to adapt to a variable environment. This is possible due to the fluctuating capacities of foraging species to consume alternate resources. This suggestion is sustained by our results, which indicate that none of the models that matched field observations were fully connected. This plasticity may contribute to the persistence of these communities. We propose that qualitative simulations represent a powerful technique to raise new hypotheses concerning community dynamics and to reconstruct guidelines that may govern community patterns.

A Multi-Criteria Analysis of Spelt Food Processing Alternatives on Small Organic Farms

ABSTRACT The nutritional, technological and processing characteristics of spelt wheat make it suitable for organic farming. Furthermore, spelt wheat can be directly processed into different kinds of food products on the farm itself, and represents additional business and market opportunities for organic farmers. In this paper we examine different spelt processing alternatives on a chosen organic farm in northeastern Slovenia. Simulation modeling, cost-benefit analysis and multi-criteria decision analysis were applied in order to find the most suitable spelt processing solution for the analyzed farm. The presented methodological framework upgrades the standard financial cost-benefit analysis with a quantitative utility function and a qualitative DEX-i modeling approach. The calculation of utility function (u) and DEX-i evaluation produced the following spelt processing project rankings: spelt husking (u = 2,67) spelt cookies (u = 2,18), spelt flour (u = 1,65) and spelt bread (u = 1,63). The proposed methodology enables multi-criteria spelt processing project ranking; however, further studies are suggested for the development of multi-criteria decision analysis-based methods for this topic.

A qualitative dynamical modelling approach to capital accumulation in unregulated fisheries

Capital accumulation has been a major issue in fisheries economics over the last two decades, whereby the interaction of the fish and capital stocks were of particular interest. Because bio-economic systems are intrinsically complex, previous efforts in this field have relied on a variety of simplifying assumptions. The model presented here relaxes some of these simplifications. Problems of tractability are surmounted by using the methodology of qualitative differential equations (QDE). The theory of QDEs takes into account that scientific knowledge about particular fisheries is usually limited, and facilitates an analysis of the global dynamics of systems with more than two ordinary differential equations. The model is able to trace the evolution of capital and fish stock in good agreement with observed patterns, and shows that over-capitalization is unavoidable in unregulated fisheries.

Predicting the effects of perturbations on ecological communities: what can qualitative models offer?

Summary 1 Quantitative predictions of the effects of perturbations on communities of interacting species have often proved to be difficult. However, if precise predictions are not a requirement then qualitative models of community dynamics offer an alternative method for predicting species responses to perturbations. 2 We used two qualitative modelling approaches to predict the effects of predator control on the fledging rate of an endangered New Zealand bird, the North Island kokako. The first approach was based on loop analysis and provided predictions on the probable direction of change in species abundances to single species perturbations. The second approach, ‘fuzzy interaction webs’, used fuzzy logic in the framework of a fuzzy cognitive map to provide predictions on the probable magnitude of change in species abundances to perturbations. 3 Using both methods, we predicted the qualitative change in the equilibrium fledging rates of kokako under various regimes of single- and multispecies predator control (ship rats, brushtail possums and stoats). Single species control was insufficient to lift the fledging rate from ‘low’ to ‘moderate’. However, simultaneous control of both ship rats and possums had the greatest influence on the fledging rates compared with any other combination as a result of the additional indirect effect of ship rat control on stoat abundance. 4 We propose qualitative modelling of community dynamics as a method suitable for predicting the effects of perturbations in complex ecological communities that can encapsulate diverse sources of knowledge about food web interactions. We believe that these methods are a useful set of heuristic tools that can be used to propose testable hypotheses about ecosystem functioning that can complement existing statistical and quantitative modelling approaches.

Methodologies in conflict: achieving synergies between system dynamics and organizational cybernetics

AbstractCoping with complexity is at the heart of the systems approach. Several methodologies can be discerned which have proved to possess extraordinary power in dealing with complex issues. System dynamics is a general‐purpose methodology for modelling and simulation employed in order to deal with dynamic complexity. Cybernetics has brought forth structural models to enable organizations to deal with the complexity of their environments. The main proposition of this paper is that these two methodological strands show potential synergies. A proposal for leveraging the complementarities of system dynamics and organizational cybernetics is made. The paper also argues that it is necessary to conflate qualitative and quantitative modelling and design approaches, as well as to improve the quality of models and strategies by strengthening the processes of validation. At a higher level of abstraction, the author postulates that, for the sake of relevance, this methodological synthesis is to build upon both the positivist and interpretivist traditions. On this basis, a framework called integrative systems methodology is proposed to help actors at different levels to achieve the requisite variety. Copyright © 2004 John Wiley & Sons, Ltd.

Strategic brand value: Advancing use of brand equity to grow your brand and business

Businesses that intend to reap the benefits of using brand as a driver of business success need to begin the process by identifying and managing, in a more systematic and structured way, the associations that contribute to brand equity and are critical to enhancing the brand's value and the extent that it financially impacts on the business. This paper is designed to acquaint the reader with a more strategic approach to both profiling and managing brand equity over time, using both qualitative and quantitative modelling approaches whose findings are correlated to business performance concerns.

Improvements and critique on Sugeno's and Yasukawa's qualitative modeling

Investigates Sugeno's and Yasukawa's (1993) qualitative fuzzy modeling approach. We propose some easily implementable solutions for the unclear details of the original paper, such as trapezoid approximation of membership functions, rule creation from sample data points, and selection of important variables. We further suggest an improved parameter identification algorithm to be applied instead of the original one. These details are crucial concerning the method's performance as it is shown in a comparative analysis and helps to improve the accuracy of the built-up model. Finally, we propose a possible further rule base reduction which can be applied successfully in certain cases. This improvement reduces the time requirement of the method by up to 16% in our experiments.

Fault Detection of a Diesel Injection System by Qualitative Modelling

The paper presents a method for onboard-diagnosis which combines a model-based diagnostic scheme with a qualitative modelling approach. It is shown how a qualitative model which represents the qualitative, discrete-event behaviour of the system can be set up in a systematic way by abstraction or by qualitative identification. Experimental results are given for the qualitative modelling and fault detection of a Common-Rail diesel injection system.

Qualitative Multi-attribute Modeling and its Application in Housing

Hierarchical multi-attribute models are aimed at the classification or evaluation of options that occur in a decision process. They decompose the problem into smaller and less complex subproblem and represent it by a hierarchy of attributes and utility functions. This article describes a qualitative modeling approach, which is supported by an expert system shell DEX and whose models are characterised by qualitative attributes and if-then rules. The approach is presented using a real-world case: allocation of housing loans at the Housing Fund of the Republic of Slovenia. The article focuses on the design, implementation and evolution of the corresponding multi-attribute models, and presents the lessons learned during the ten years of the system’s exploitation.

Feedback analysis in reserve management: studying local myths using qualitative models

A qualitative modelling approach is used to highlight potential feedback mechanisms and secondary effects of management actions on a number of key species in a large Argentine wetland. The development of this qualitative model, in this case a loop model, was a first step in the creation of an overall management and monitoring programme for this important wetland. The use of loop models is a possible strategy in environmental management and monitoring programmes of large complex natural reserves, in which little quantitative data is available. Based upon observed ecological information, several loop trophic models were constructed and appropriate links made to reflect actual trophic relationships between trophic variables. The potential secondary effects of a hunting ban on caiman in a large shallow lagoon were examined. Indirect secondary effects were found to produce unforeseen negative impacts on other predator species (piscivorous birds, piranha) and species important to the abiotic environment (large bottom dwelling fish). As there are limited quantitative data, field investigations and the development of other types of models are necessary to examine in detail the quantitative variations on the populations in question. The results of this model were found useful to indicate where further study and quantitative data gathering might be best focused.

Syndromes of Global Change: a qualitative modelling approach to assist global environmental management

A novel transdisciplinary approach to investigate Global Change (GC) is presented. The approach rests on the decomposition of the intrigue dynamics of GC into patterns of civilization–nature interactions (“syndromes”) by an iterative scientific process of observations, data and system theoretical analyses, and modelling attempts. We illustrate the approach by a detailed analysis of the Sahel Syndrome, which describes the rural poverty driven overuse of natural resources. The investigation is performed by (i) identifying relevant “symptoms” and interlinkages which are characteristics for this pattern, and (ii) a qualitative model representing the internal dynamics of the essential flywheel. The geographical patchwork of the regions affected by the syndrome which is obtained by global data analysis, proves the high global relevance of this pattern. The qualitative model is employed for an evaluation of basic policy strategies debated in the context of rural poverty driven environmental degradation. It turns out that a mixed policy of combating poverty and introducing soil preserving agricultural techniques and practices is most promising to tackle the syndrome dynamics.

A genetic-based neuro-fuzzy approach for modeling and control of dynamical systems

Linguistic modeling of complex irregular systems constitutes the heart of many control and decision making systems, and fuzzy logic represents one of the most effective algorithms to build such linguistic models. In this paper, a linguistic (qualitative) modeling approach is proposed. The approach combines the merits of the fuzzy logic theory, neural networks, and genetic algorithms (GA's). The proposed model is presented in a fuzzy-neural network (FNN) form which can handle both quantitative (numerical) and qualitative (linguistic) knowledge. The learning algorithm of an FNN is composed of three phases. The first phase is used to find the initial membership functions of the fuzzy model. In the second phase, a new algorithm is developed and used to extract the linguistic-fuzzy rules. In the third phase, a multiresolutional dynamic genetic algorithm (MRD-GA) is proposed and used for optimized tuning of membership functions of the proposed model. Two well-known benchmarks are used to evaluate the performance of the proposed modeling approach, and compare it with other modeling approaches.

Interactive Decision Support System for Building Construction Scheduling

The present paper describes the main findings of a study that focused on the modeling of the logic of building construction schedules and particularly activity dependencies. The work resulted in a scheduling model that provides a theoretical framework for the development of scheduling tools and computer programs. The main features of the new model are the following: (1) Support for strategic, early planning decisions and the systematic preparation of schedules; (2) generic procedures that enable the automatic generation of initial schedules; (3) representations for better understanding of the construction process at the project level; and (4) means to obtain specific reports explaining the logic of a schedule. This model is based on the qualitative modeling approach, findings from the literature, and fieldwork conducted within construction companies. The model has been successfully implemented and tested in the form of a computer program.

Automatic synthesis of batch plant procedures: Process‐oriented approach

AbstractA strategy for the automatic synthesis of plant operating procedures, through the integration of artificial intelligence and mathematical modeling tools is discussed. This “predicative/numerical” modeling paradigm integrates qualitative and quantitative aspects of the problem in a same framework. It uses a “process‐centered” qualitative modeling approach together with MILP optimization techniques to automatically generate operating strategies. The operation procedures network (OP‐Net), formulated in terms of processes from a generic library, describes abstract (hardware‐independent) processing paths leading to the desired operational goals. In this approach, the model assumptions, conservation expressions and data are described at the same level of abstraction, using the same formal representation. This permits the direct, automatic generation and modification of operation procedures in situations involving changes in basic assumptions and initial scenarios. Thus, flexibility, an essential feature of batch processing, is safeguarded.

ON THE MODELLING APPROACHES OF BIOMASS BEHAVIOUR IN BIOREACTOR

Abstract This paper offers a critical review of various modelling techniques to describe the behaviour of microorganisms in a bioreactor. Several approaches from the simplest unstructured to the structured stochastic type are examined to highlight the basic methodologies, the capacity to describe the phenomena occurring and the diOiculties on the experimental validation. The effects of macromixing are updated using the chemical reactor methodologies. The inside mechanisms of microorganisms and their interaction with reactor fluid dynamics are outlined in term of comparison of their relaxation time; this suggestion provides a useful tool to analyze continuous bioreactors. Lastly the potentialities of qualitative and semi-quantitative modelling approaches are outlined to study biochemical phenomena and bioreactor features, focusing the attention on “fuzzy” and o[M] (order of magnitude) techniques.

Process modelling for intelligent control

This contribution considers the problem of knowledge representation in intelligent control systems: the kind of knowledge that is required and how this may be encapsulated within an application framework. It is argued that rule-base techniques need to be supplemented by other methods in order to express certain pertinent aspects of the domain. After a brief discussion of qualitative modelling techniques, attention is focused upon numerical models and a relatively new qualitative modelling approach, Qualitative Transfer Functions. The effectiveness of the latter model forms as repositories of deep knowledge are evaluated by application to a simulated distillation plant. The results indicate that although numerical models can provide accurate input-output representations, the integrated framework offered by Qualitative Transfer Functions is capable of carrying more information relevant to decision-making systems.

Logic Modelling of Dependable Systems

Abstract One approach to achieving fault tolerance in a complex engineered system is to include within it an automated Fault Management (sub)System (FMS), in addition to conventional monitoring by human operators. The FMS assists in ensuring an appropriate response to component failures by generating commands to switch system resource usage, control mode, redundancy etc on the basis of sensor data. The specification of the required logical behaviour of the FMS must be derived from a consideration of the total system behaviour in the nominal case and under failure assumptions and should be compatible with operational procedures demanded from human operators. This typically leads to significant levels of complexity due to the proliferation of possible system states. A recently developed computer-based tool, called Integrated Fault Management Environment (IFME), addresses this problem. IFME provides a graphical interface for specifying hierarchical system structure, interdependencies and logical behaviours. The defined logical system model may then be subjected to various analyses supported by the toolset, including batch-type and interactive simulation, diagnostic rule induction, Failure Mode Effects Analysis (FMEA) and operations procedures design. The logic (or qualitative) modelling approach is evaluated and placed in the context of conventional systems and control engineering techniques.

Automatic Synthesis of Chemical Batch Plant Procedures: A Qualitative Process-Centered Approach

This paper describes a system for the synthesis of batch operating procedures that is based on an “process-centered” qualitative modeling approach and MILP optimization. The concept of the Operation Procedures Network (OPNet) is introduced to describe the possible abstract (i.e. hardware independent) processing paths leading to the desired goal from a given starting scenario. The solution method is hierarchically organized into: (1) OPNnet generation, (2) its translation into a mixed integer parametric model (now hardware specific), (3) the “optimal” solution of this MIP problem, and (4) determining the sequence of simple operator actions required to carry out the processing tasks.

Intelligent systems for traffic flow management: A qualitative modeling approach

Presents an approach for the design of intelligent systems for traffic control. The article first discusses the type of problems to be modeled ( behavior in networks and main flow axes). Secondly an approach to the knowledge representation is proposed. Although specific traffic aspects are discussed, the proposed approach can be understood in a more general way as a general reasoning concept for an architecture for management purposes.

Modelling Expertise for KBS Development

The benefits of a qualitative modelling approach to building knowledge-based systems include better project control, communication between participants, more accurate validation and easier maintenance. Knowledge acquisition from experts will be more successful if a conceptual model is developed from a knowledge level description, to act as a publicly examinable basis for system design. Analytical tools are available to structure both content and process knowledge on paper, before any commitment is made to implementation. The role of abstraction in developing models of generic tasks as a set of templates for conceptual model development is reviewed, with particular regard to knowledge acquisition tools. Modelling problem-solving methods, especially for constructive tasks such as planning, is more difficult than modelling content knowledge. Epistemological support for conceptual abstraction, particularly at middle levels, remains inadequate.