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Article
Publication date: 2 January 2018

Abdennacer Ben Messaoud, Samia Talmoudi and Moufida Ksouri-Lahmari

The purpose of this paper is to propose a new method for computing validities in the multimodel approach.

Abstract

Purpose

The purpose of this paper is to propose a new method for computing validities in the multimodel approach.

Design/methodology/approach

The multimodel approach offers an interesting alternative and a powerful tool to bypass the difficulties to model, control and diagnose a nonlinear and complex system. Its idea is defined as the apprehension of a nonlinear behaviour of a system by a set of local models characterizing the system operation in different operating zones. In spite of the success of its application in different fields, many problems related to the synthesis of multimodel approach remain open. These include, in particular, the method of obtaining the contribution degrees, also called validities, of the base-models for the deduction of the multimodel output.

Findings

The presented method may lead to superior results in comparison with the residue approach commonly used in the calculation of validities. Numerical simulation results and an experimental validation on a semi-batch reactor clearly illustrated the effectiveness of the proposed method and proved its impact on the improvement of the performances of the multimodel approach. Moreover, the multimodel approach using the new validities’ computation method can lead to perfect modelling of the process.

Practical implications

The proposed method discussed in the paper has the potential to make the multimodel approach more efficient in the modelling of complex real systems.

Originality/value

A significant contribution of the paper is the formulation of a new constrained optimization problem that can be solved by using a powerful mathematical tool such as the active set method, allowing to estimate the validity indexes in the multimodel approach. The obtained optimal solution can lead to perfect modelling of nonlinear and complex real systems.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 23 August 2011

Raja Ben Mohamed, Hichem Ben Nasr and Faouzi M'Sahli

The purpose of this paper is to present a new concept based on a neural network validity approach in the area of multimodel for complex systems.

Abstract

Purpose

The purpose of this paper is to present a new concept based on a neural network validity approach in the area of multimodel for complex systems.

Design/methodology/approach

The multimodel approach was recently developed in order to solve the modeling problems and the control of complex systems. The strategy of this approach coincides with the usual approach of the engineer which consists in subdividing a complex problem to a set of simple, manageable sub‐problems that can be solved separately. However, this approach still faces some problems in design, especially in determining models and in finding the appropriate method of calculating validities.

Findings

A novel approach based on neural network validity shows very remarkable performances in multimodel for complex systems.

Research limitations/implications

The validity of each model is based on the convergence of each neural network. For a fast convergence the proposed approach can be online to give a good performance in multimodel representation for system with rapid dynamics.

Practical implications

The proposed concept discussed in the paper has the potential to be applied to complex systems.

Originality/value

The suggested approach is implemented and reviewed with a complex dynamic and fast process compared to the residue approach commonly used in the calculation of validities. The results prove to be satisfactory and show a good accuracy.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 4 no. 3
Type: Research Article
ISSN: 1756-378X

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Article
Publication date: 1 December 1996

Wai Ming Tam and Yin Cheong Cheng

Believes that an urgent need for in‐depth understanding of the relationship of staff development to education quality exists in current educational reforms, policy making…

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2500

Abstract

Believes that an urgent need for in‐depth understanding of the relationship of staff development to education quality exists in current educational reforms, policy making, and teacher education. Based on the existing knowledge of education quality, quality management and effective schools, aims to propose a framework to show how staff development can be designed and managed to contribute to the assurance and enhancement of school education quality from the perspective of seven multimodels of school education quality. Different models emphasize different aspects of school education quality and propose different strategies to enhance it. For ensuring long‐term school education quality in a changing educational environment, staff development can be organized and managed according to the major concerns of multimodels. Proposes some practical considerations for designing and implementing school‐based staff development.

Details

Training for Quality, vol. 4 no. 4
Type: Research Article
ISSN: 0968-4875

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Article
Publication date: 1 December 2002

Martin Hrubý, Radek Kočí, Petr Peringer and Zdena Rábová

The process of creating complex models often requires different modelling methods and tools to be integrated. This paper provides a concise description of an…

Abstract

The process of creating complex models often requires different modelling methods and tools to be integrated. This paper provides a concise description of an object‐oriented environment for creating composite models. The proposed approach is based on using simulation abstractions as basic model building blocks. The basic environment is built up of a Prolog interpreter, SIMLIB and object‐oriented Petri nets.

Details

Kybernetes, vol. 31 no. 9/10
Type: Research Article
ISSN: 0368-492X

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Book part
Publication date: 26 October 2012

Geoffrey P. Morgan and Kathleen M. Carley

We present a simulation designed to capture the impact of both formal authority ties and informal socialization ties on the performance of an organization adapting to a…

Abstract

We present a simulation designed to capture the impact of both formal authority ties and informal socialization ties on the performance of an organization adapting to a turbulent world. We present a summary of three key models that informed our approach and then outline and describe the operation of our resulting simulation. Using an experiment that manipulated both the authority network structure and the stress the organization placed on socialization, we show inefficient authority structures harm performance, and also that socialization has a strong and nonlinear impact on peak organizational performance and on the performance of top management. We also present a case study, instantiating the general model with the specific context of a real-world organization. Finally, our integrated multimodel suggests that companies should pursue different strategies in hiring key strategic actors than they do for other actors.

Details

The Garbage Can Model of Organizational Choice: Looking Forward at Forty
Type: Book
ISBN: 978-1-78052-713-0

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Article
Publication date: 4 January 2011

Alioune Badara Mboup, François Guerin, Dimitri Lefebvre and Pape Alioune Ndiaye

The purpose of this paper is to describe a two‐level hierarchical control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the…

Abstract

Purpose

The purpose of this paper is to describe a two‐level hierarchical control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the control design is to perform the energy transfers, according to the sources power variations and the load characteristics.

Design/methodology/approach

The controller determines the operating mode of the multisource renewable energy system and the power ratio provided by each source to satisfy the load demand. The study is based on an accurate model of the DC/DC converters coupled on the DC bus. The performance of the controller is compared with the usual method based on the measurements of the system variables with sensors (solar radiation, shaft speed, voltages, and currents).

Findings

The proposed method does not need extra sensors to measure the available power for each source.

Research limitations/implications

The method is developed for an hybrid system with two sources (photovoltaic and lead‐acid battery bank) and specific zero voltage switch full‐bridge isolated buck DC/DC power converters but can easily extended to more sources and other classes of DC/DC converters.

Practical implications

The method is assessed through computer simulations using a simple comprehensive model. An experimental device is also developed by the GREAH Research Group of University Le Havre (France). The GREAH also participates to a technologic centre with similar topology on the site of Fecamp (France).

Social implications

The proposed autonomous control schema is suitable to control hybrid systems with several energy sources in remote areas.

Originality/value

The main contributions of this work are first to introduce a two stages controller and second to use the duty cycle value of the power converters as decision criteria to switch off/on the sources.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 March 1977

M. SUGENO and T. TERANO

Using fuzzy measures and fuzzy integrals, the paper presents a mathematical model of learning which is able to learn through fuzzy information. The characteristics of the…

Abstract

Using fuzzy measures and fuzzy integrals, the paper presents a mathematical model of learning which is able to learn through fuzzy information. The characteristics of the model are studied theoretically and in numerical examples, where the model is compared with an ordinary Bayesian learning model. The problem of seeking an extremum of multimodel objective function is given as an example.

Details

Kybernetes, vol. 6 no. 3
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 1 March 1995

Lawrence Mann, Anuj Saxena and Gerald M. Knapp

The focus of preventive maintenance (PM) programmes in industry isshifting from a pure statistical basis to online condition monitoring.Examines the shortcomings of…

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3930

Abstract

The focus of preventive maintenance (PM) programmes in industry is shifting from a pure statistical basis to online condition monitoring. Examines the shortcomings of statistical‐based PM which are contributing to this shift, and the potential benefits of and current research issues within condition‐based PM. Notes that statistics and quality control techniques will continue to play a critical role in this evolution.

Details

Journal of Quality in Maintenance Engineering, vol. 1 no. 1
Type: Research Article
ISSN: 1355-2511

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Article
Publication date: 13 November 2009

Weida Xu and Tianyuan Xiao

The purpose of this paper is to introduce robust optimization approaches to balance mixed model assembly lines with uncertain task times and daily model mix changes.

Abstract

Purpose

The purpose of this paper is to introduce robust optimization approaches to balance mixed model assembly lines with uncertain task times and daily model mix changes.

Design/methodology/approach

Scenario planning approach is used to represent the input data uncertainty in the decision model. Two kinds of robust criteria are provided: one is min‐max related; and the other is α‐worst scenario based. Corresponding optimization models are formulated, respectively. A genetic algorithm‐based robust optimization framework is designed. Comprehensive computational experiments are done to study the effect of these robust approaches.

Findings

With min‐max related robust criteria, the solutions can provide an optimal worst‐case hedge against uncertainties without a significant sacrifice in the long‐run performance; α‐worst scenario‐based criteria can generate flexible robust solutions: through rationally tuning the value of α, the decision maker can obtain a balance between robustness and conservatism of an assembly line task elements assignment.

Research limitations/implications

This paper is an attempt to robust mixed model assembly line balancing. Some more efficient and effective robust approaches – including robust criteria and optimization algorithms – may be designed in the future.

Practical implications

In an assembly line with significant uncertainty, the robust approaches proposed in this paper can hedge against the risk of poor system performance in bad scenarios.

Originality/value

Using robust optimization approaches to balance mixed model assembly line.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 17 June 2008

Aitor Bilbao‐Guillerna, Manuel de la Sen and Santiago Alonso‐Quesada

The purpose of this paper is to improve the transient response and the inter‐sample behavior of a model reference adaptive control system by an appropriate selection of…

Abstract

Purpose

The purpose of this paper is to improve the transient response and the inter‐sample behavior of a model reference adaptive control system by an appropriate selection of the fractional order hold (FROH) gain β and the multirate gains used in the control reconstruction signal through a fully freely chosen reference model even when the continuous plant possesses unstable zeros.

Design/methodology/approach

A multiestimation adaptive control scheme for linear time‐invariant continuous‐time plant with unknown parameters is presented. The set of discrete adaptive models is calculated from a different combination of the correcting gain β in a FROH and the set of gains to reconstruct the plant input under multirate sampling with fast input sampling. Then the scheme selects online the model with the best continuous‐time tracking performance which includes a measure of the inter‐sample ripple, which is improved. The estimated discrete unstable zeros are avoided through an appropriate design of the multirate gains so that the reference model might be freely chosen with no constraints on potential unstable zeros.

Findings

The scheme is able to select online the discretization model with the best continuous‐time tracking performance without an appropriate initialization.

Research limitations/implications

The switching mechanism among the different models should maintain in operation the active discretization model at least for a minimum residence time in order to guarantee closed‐loop stability. The inter‐sample behavior is improved, but it is not always completely removed.

Practical implications

The transient response and the inter‐sample behavior are improved by using this multiestimation‐based discrete controller compared with a single estimation‐based one. The implementation of discrete controllers makes it easier and cheaper to implement and also more reliable than continuous‐time controllers.

Originality/value

The main innovation of the paper compared with previous background work is that the reference output is supplied by a stable continuous transfer function. Then the scheme is able to partly regulate the continuous‐time tracking error while the controller is essentially discrete‐time and operated by a FROH in general.

Details

Kybernetes, vol. 37 no. 6
Type: Research Article
ISSN: 0368-492X

Keywords

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