The Experts below are selected from a list of 72714 Experts worldwide ranked by ideXlab platform

Catherine Meadows - One of the best experts on this subject based on the ideXlab platform.

Xiaolan Xie - One of the best experts on this subject based on the ideXlab platform.

  • supervisory controller of petri nets under partial observation
    IFAC Proceedings Volumes, 2004
    Co-Authors: Zied Achour, Nidhal Rezg, Xiaolan Xie
    Abstract:

    Abstract We propose in this paper a control synthesis policy for the forbidden state problems of bounded Petri nets (PN) with liveness requirement and uncontrollable / unobservable transitions. The proposed approach computes a maximally permissive PN controller, whenever such a controller exists. The first step, based on a Ramadge-Wonham theory, determines the refined controlled observer reachability graph of the controlled PN. In the second step, the theory of regions is used to generate a set of control places to be added to the plant PN model. These control places guarantee the Desired Behavior. The proposed approach is illustrated on a manufacturing example.

  • design of a live and maximally permissive petri net controller using the theory of regions
    International Conference on Robotics and Automation, 2003
    Co-Authors: Asma Ghaffari, Nidhal Rezg, Xiaolan Xie
    Abstract:

    This paper addresses the forbidden state problem of Petri nets (PN) with liveness requirement and uncontrollable transitions. The proposed approach computes a maximally permissive PN controller, whenever such a controller exists. The first step, based on a Ramadge-Wonham-like reasoning (1989), determines the legal and live maximal Behavior the controlled PN should have. In the second step, the theory of regions is used to design control places to add to the original model to realize the Desired Behavior. Furthermore, necessary and sufficient conditions for the existence of control places realizing the maximum permissive control are given. A parameterized manufacturing application of significant state space is used to show the efficiency of the proposed approach.

Jorge Otavio Trierweiler - One of the best experts on this subject based on the ideXlab platform.

  • multivariable pid controller design for chemical processes by frequency response approximation
    Chemical Engineering Science, 2013
    Co-Authors: Marcelo Escobar, Jorge Otavio Trierweiler
    Abstract:

    Abstract In this paper we propose a systematic approach to designing low order controllers for chemical processes using frequency response approximation. The method consists of four major steps: (i) the Desired Behavior for the closed-loop system in the time domain is specified. The achievable performance of the closed loop is determined to ensure internal stability because of process inherent characteristics, i.e., non-minimum phase elements; (ii) the frequency response of the “ideal” controller, which is usually high order and too complex to be realized, is algebraically determined; (iii) this response is approximated in the frequency domain through a structured low order controller with PID parameters; and finally (iv) a closed loop simulation provides design evaluation. This novel design procedure is demonstrated through two case studies. These successful applications demonstrate its efficiency and applicability to the design of low order multivariable controllers for complex industrial processes.

  • multivariable low order structured controller design by frequency response approximation
    Brazilian Journal of Chemical Engineering, 2000
    Co-Authors: Jorge Otavio Trierweiler, R Muller, S Engell
    Abstract:

    The method presented here offers an effective and time saving tool for multivariable controller design. The relation between controller complexity and closed loop performance can easily be evaluated. The method consists of five steps: 1. A Desired Behavior of the closed loop system is specified. Considering the nonminimum phase part of the process model the closed loop attainable performance is determined. 2. The process model and the attainable performance are scaled by the RPN-scaling procedure. 3. This defines an "ideal" scaled controller, which is usually too complex to be realized. 4. The frequency response of the ideal scaled compensator is approximated by a simpler one with structure and order chosen by the user. 5. Since the approximation in frequency response is performed with the scaled system, it is necessary to return to the original system’s units.

Mirdita N Elstak - One of the best experts on this subject based on the ideXlab platform.

  • flipping the identity coin the comparative effect of perceived projected and Desired organizational identity on organizational identification and Desired Behavior
    2007
    Co-Authors: Mirdita N Elstak
    Abstract:

    textabstractIt is especially during times of uncertainty or change in an organization, that a major concern for organizational management is how to elicit and maintain a high degree of identification and Desired Behavior from their members. Traditionally, scholars have taken a "bottom-up approach" in understanding these organizational processes, where the assumption is that members’ own, private perceptions of who their organization is, i.e. their perceived organizational identity, is the core driver of their identification and Behavior. I challenge this one-sided approach of perceived organizational identity on the grounds that by focusing solely on members’ organizational identity perceptions, we disregard the "top-down approach", i.e. the important role that management plays in setting an overall collective framework that directs and guides members in their identification and Behavior. This dissertation is the first to empirically test the comparative significance of bottom-up and top-down identity types. Through three empirical studies in two different organizational settings, I study this force field between the bottom-up and top-down identity processes. My results indicate that especially during times of threat and organizational change, the role of perceived organizational identity is not nearly as prevalent as generally assumed. It is not only the perceived organizational identity in and of itself that drives identification and Behavior, but also the degree to which members believe that their perceived organizational identity is consistent with the top-down determined identity types of projected and Desired organizational identity. In doing so, this work takes a more integrative approach to organizational identity processes.

  • the comparative effect of perceived projected and Desired organizational identity on organizational identification and Desired Behavior
    2001
    Co-Authors: C B M Van Riel, Mirdita N Elstak
    Abstract:

    It is especially during times of uncertainty or change in an organization, that a major concern for organizational management is how to elicit and maintain a high degree of identification and Desired Behavior from their members. Traditionally, scholars have taken a “bottom-up approach” in understanding these organizational processes, where the assumption is that members’ own, private perceptions of who their organization is, i.e. their perceived organizational identity, is the core driver of their identification and Behavior. I challenge this one-sided approach of perceived organizational identity on the grounds that by focusing solely on members’ organizational identity perceptions, we disregard the “top-down approach”, i.e. the important role that management plays in setting an overall collective framework that directs and guides members in their identification and Behavior. This dissertation is the first to empirically test the comparative significance of bottom-up and top-down identity types. Through three empirical studies in two different organizational settings, I study this force field between the bottom-up and top-down identity processes. My results indicate that especially during times of threat and organizational change, the role of perceived organizational identity is not nearly as prevalent as generally assumed. It is not only the perceived organizational identity in and of itself that drives identification and Behavior, but also the degree to which members believe that their perceived organizational identity is consistent with the top-down determined identity types of projected and Desired organizational identity. In doing so, this work takes a more integrative approach to organizational identity processes.

M. A. Keane - One of the best experts on this subject based on the ideXlab platform.

  • Automatic Design of Analog Electrical Circuits Using . . .
    2000
    Co-Authors: J. R. Koza, F. H Bennett, D. Andre, M. A. Keane
    Abstract:

    The design (synthesis) of analog electrical circuits entails the creation of both the topology and sizing (numerical values) of all of the circuit's components. There has previously been no general automated technique for automatically designing an analog electrical circuit from a high-level statement of the circuit's Desired Behavior. This chapter introduces genetic programming and shows how it can be used to automate the design of both the topology and sizing of a suite of five prototypical analog circuits, including a lowpass filter, a tri-state frequency discriminator circuit, a 60 dB amplifier, a computational circuit for the square root, and a time-optimal robot controller circuit. The problem-specific information required for each of the eight problems is minimal and consists primarily of the number of inputs and outputs of the Desired circuit, the types of available components, and a fitness measure that restates the high-level statement of the circuit's Desired Behavior as a measurable mathematical quantity. All five of these genetically evolved circuits constitute instances of an evolutionary computation technique solving a problem that is usually thought to require human intelligence

  • Synthesis of Topology and Sizing of Analog Electrical Circuits by Means of Genetic Programming
    1998
    Co-Authors: J. R. Koza, F. H Bennett, D. Andre, M. A. Keane
    Abstract:

    The design (synthesis) of an analog electrical circuit entails the creation of both the topology and sizing (numerical values) of all of the circuit's components. There has previously been no general automated technique for automatically creating the design for an analog electrical circuit from a high-level statement of the circuit's Desired Behavior. This paper shows how genetic programming can be used to automate the design of eight prototypical analog circuits, including a lowpass filter, a highpass filter, a bandstop filter, a tristate frequency discriminator circuit, a frequency-measuring circuit, a 60 dB amplifier, a computational circuit for the square root function, and a time-optimal robot controller circuit

  • Evolutionary design of analog electrical circuits using genetic programming
    Springer Verlag, 1998
    Co-Authors: J. R. Koza, F. H Bennett, D. Andre, M. A. Keane
    Abstract:

    Abstract. The design (synthesis) of analog electrical circuits entails the creation of both the topology and sizing (numerical values) of all of the circuit's components. There has previously been no general automated technique for automatically designing an analog electrical circuit from a high-level statement of the circuit's Desired Behavior. This paper shows how genetic programming can be used to automate the design of both the topology and sizing of a suite of five prototypical analog circuits, including a lowpass filter, a tri-state frequency discriminator circuit, a 60 dB amplifier, a computational circuit for the square root, and a timeoptimal robot controller circuit. All five of these genetically evolved circuits constitute instances of an evolutionary computation technique solving a problem that is usually thought to require human intelligence. 1

  • Automated Synthesis of Analog Electrical Circuits by Means of Genetic Programming
    1997
    Co-Authors: J. R. Koza, F. H Bennett, D. Andre, M. A. Keane, Frank Dunlap
    Abstract:

    The design (synthesis) of analog electrical circuits starts with a highlevel statement of the circuit's Desired Behavior and requires creating a circuit that satisfies the specified design goals. Analog circuit synthesis entails the creation of both the topology and the sizing (numerical values) of all of the circuit's components. The difficulty of the problem of analog circuit synthesis is well known and there is no previously known general automated technique for synthesizing an analog circuit from a high-level statement of the circuit's Desired Behavior. This paper presents a single uniform approach using genetic programming for the automatic synthesis of both the topology and sizing of a suite of eight different prototypical analog circuits, including a lowpass filter, a crossover (woofer and tweeter) filter, a source identification circuit, an amplifier, a computational circuit, a timeoptimal controller circuit, a temperature-sensing circuit, and a voltage reference circuit. The problem-specific information required for each of the eight problems is minimal and consists primarily of the number of inputs and outputs of the Desired circuit, the types of available components, and a fitness measure that restates the highleve