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Qualitative and Quantitative Simulation: Bridging the Gap
 Artificial Intelligence
, 1997
"... Shortcomings of qualitative simulation and of quantitative simulation motivate combining them to do simulations exhibiting strengths of both. The resulting class of techniques is called semiquantitative simulation. One approach to semiquantitative simulation is to use numeric intervals to represe ..."
Abstract

Cited by 43 (1 self)
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Shortcomings of qualitative simulation and of quantitative simulation motivate combining them to do simulations exhibiting strengths of both. The resulting class of techniques is called semiquantitative simulation. One approach to semiquantitative simulation is to use numeric intervals to represent incomplete quantitative information. In this research we demonstrate semiquantitative simulation using intervals in an implemented semiquantitative simulator called Q3. Q3 progressively refines a qualitative simulation, providing increasingly specific quantitative predictions which can converge to a numerical simulation in the limit while retaining important correctness guarantees from qualitative and interval simulation techniques. Q3's simulations are based on a technique we call step size refinement. While a pure qualitative simulation has a very coarse step size, representing the state of a system trajectory at relatively few qualitatively distinct states, Q3 interpolates newly expl...
HigherOrder Derivative Constraints in Qualitative Simulation
 Artificial Intelligence
, 1991
"... Qualitative simulation is a useful method for predicting the possible qualitatively distinct behaviors of an incompletely known mechanism described by a system of qualitative differential equations (QDEs). Under some circumstances, sparse information about the derivatives of variables can lead to in ..."
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Cited by 7 (3 self)
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Qualitative simulation is a useful method for predicting the possible qualitatively distinct behaviors of an incompletely known mechanism described by a system of qualitative differential equations (QDEs). Under some circumstances, sparse information about the derivatives of variables can lead to intractable branching (or "chatter") representing uninteresting or even spurious distinctions among qualitative behaviors. The problem of chatter stands in the way of real applications such as qualitative simulation of models in the design or diagnosis of engineered systems. One solution to this problem is to exploit information about higherorder derivatives of the variables. We demonstrate automatic methods for identification of chattering variables, algebraic derivation of expressions for secondorder derivatives, and evaluation and application of the sign of second and thirdorder derivatives of variables, resulting in tractable simulation of important qualitative models. Caution is requir...
Dynamic Process Monitoring and Fault Diagnosis With Qualitative Models
 IEEE Transactions on Systems, Man, and Cybernetics
, 1994
"... Qualitative Modeling and Interpretation (QMI) and Qmimic are online monitoring and diagnosis systems which use multiple qualitative models of a plant to monitor noisy data streams and rapidly diagnose faults from observed dynamic behavior. Both systems continue monitoring after faults have occurred ..."
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Qualitative Modeling and Interpretation (QMI) and Qmimic are online monitoring and diagnosis systems which use multiple qualitative models of a plant to monitor noisy data streams and rapidly diagnose faults from observed dynamic behavior. Both systems continue monitoring after faults have occurred. QMI simulates normal and faulty plant behavior offline using purely qualitative Qsim models, and uses plant data to select the correct model, yielding a diagnosis. Qmimic incrementally simulates online qualitative models which describe the current behavior of the plant, using plant data to constrain further prediction and select between the models. Although both systems are based on qualitative models of the plant, Qmimic also incorporates semiquantitative data (quantitative ranges and bounding envelopes) into the qualitative simulation in order to achieve better predictions. QMI and Qmimic are described and compared in detail, and both are tested on a simulated chemical reactor. 1 Intr...