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Full-Text Articles in Engineering

Moisture Migration In Concrete Slabs During Drying, Niall Holmes, Roger West Sep 2002

Moisture Migration In Concrete Slabs During Drying, Niall Holmes, Roger West

Conference papers

This paper presents the profiles of relative humidity (RH) readings taken at various depths in concrete slabs during a time period of over 230 days using probes attached to a humidity-reading device. It also examines the effect ambient conditions have on the drying process. For the experimental work, two sets of slabs were tested, one in a controlled environment with an elevated temperature and the other in a laboratory at room temperatures. It was found, not surprisingly that the slabs in the controlled room appeared to dry out at a much faster rate than those held at room temperature. However, …


Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer Sep 2002

Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer

Conference papers

Abstract: This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.


On The Selection Of Simulation Software For Manufacturing Application, Amr Arisha, Mohie El Baradie Aug 2002

On The Selection Of Simulation Software For Manufacturing Application, Amr Arisha, Mohie El Baradie

Conference papers

The growing complexity of manufacturing along with the need for higher efficiency, greater flexibility, better product quality and lower cost urged the use of simulation in manufacturing systems. The number and variety of simulation software packages on the market increased as well. Consequently, the varieties of these packages led to some bewilderment on the part of potential users when faced the selection process. The present article addresses an overview of material addressed in journals, conferences, and textbooks on the selection of appropriate simulation software. It also suggests a classification of main criteria to be considered in evaluating simulation software packages. …


Closed Loop Identification Of A First Order Plus Dead Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer Jun 2002

Closed Loop Identification Of A First Order Plus Dead Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer

Conference papers

Abstract -- This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the …


Flow Shop Scheduling Problem: A Computational Study, Amr Arisha, Paul Young, Mohie El Baradie Jan 2002

Flow Shop Scheduling Problem: A Computational Study, Amr Arisha, Paul Young, Mohie El Baradie

Conference papers

A computational study has been developed to obtain optimal / near optimal solution for the flow shop scheduling problem with make-span minimization as the primary criterion and the minimization of either the mean completion time, total waiting time or total idle time as the secondary criterion. The objective is to determine a sequence of operations in which to process ‘n’ jobs on ‘m’ machines in same order (flow shop environment) where skipping is allowed. The Simulation approach for deterministic and stochastic flow shop scheduling has been developed. It reads and manipulates data for 500 jobs on 500 machines. Different factorial …


Critical Loading Events For The Assessment Of Medium Span Bridges, Colin C. Caprani, S. A. Grave, E. J. O'Brien, A. J. O'Connor Jan 2002

Critical Loading Events For The Assessment Of Medium Span Bridges, Colin C. Caprani, S. A. Grave, E. J. O'Brien, A. J. O'Connor

Conference papers

This paper describes the simulation of free-flowing traffic across bridges to predict the characteristic values for bridge load effects such as bending moment and shear force. The results of these simulations are then used to demonstrate that, in predicting the characteristic extreme load effects to which a bridge may be subjected, it is not sufficient to solely model one-or two-truck presence events. It is shown that loading events involving three or more trucks may need be included in the model for short to medium spans. The critical loading events for a particular load effect are strongly dependent on the span …


Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See Jan 2002

Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See

Conference papers

A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.


Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer Jan 2002

Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer

Conference papers

Non-linear processes, by their nature, are non-uniform and invariably require custom designed control schemes to deal with individual characteristics. No general theory deals comprehensively with the wide range of non-linear systems encountered. In an attempt to accurately model non-linear dynamical systems, a wide variety of techniques have been developed such as non-linear auto-regressive moving average with exogeneous inputs (NARMAX) models (Chen and Billings, 1989), Weiner models (Schetzen, 1981), Hammerstein models (Billings and Fakhouri, 1982) and Multiple Layer Perceptron (MLP) neural networks (Narendra and Kannan, 1990). While the accuracy of such models offers a potentially significant improvement over linear models, the …


Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Coyle Jan 2002

Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Coyle

Conference papers

A non-linear predictive controller is presented. It judiciously combines predictive controllers with a local model network utilizing a neural-network-like gating system. It avoids the time consuming quadratic optimization calculation, which is normally necessary in non-linear predictive control. A controller simulation on a Continuous Stirred Tank Reactor (CSTR) case study was shown to be satisfactory both in terms of set point tracking and regulation performance over the entire operating range. Moreover, the inherent integration action in the local predictive controller provides zero static offsets.


Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Coyle Jan 2002

Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Coyle

Conference papers

The velocity-based local model (LM) network is a novel modelling approach that overcomes the lack of interpretability associated with the conventional LM network technique. The global dynamics of the nonlinear network are directly related to the underlying sub-model dynamics. Thus, the velocity-based network is ideally suited to the development of local controller (LC) networks. Furthermore, the local models are continuous-time, velocity-based and linear, providing continuity with established linear theory. To date, research has focused on the continuous-time version of the velocity-based network. The application of digital computer is widely popular in the field of control and, therefore, this paper develops …


A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Coyle Jan 2002

A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Coyle

Conference papers

The basic PID controllers have difficulty in dealing with problems that appear in complex non-linear processes. This paper presents a practical non-linear PID controller that deals with these non-linear difficulties. It utilises a local model (LM) network, which combines a set of local models within an artificial neural network structure, to adaptively characterise the process non-linearity. Then a local controller network is formulated through a gating system deduced from the LMN to handle the non-linearity. A continuous stirred tank reaction (CSTR) case study illustrates the practicality of this method in the modelling and control of non-linear processes. PID controllers are …


Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer Jan 2002

Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer

Conference papers

This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI controllers whose parameters are specified using appropriate tuning rules. The gain margin and phase margin of the compensated system, as the ratio of time delay to time constant of the process varies, are calculated for each tuning rule and an expert system is used to recommend a tuning rule for user defined requirements.


Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer Jan 2002

Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the process can …


Regenerative Magnet Load Power Supply With Utility Friendly Operations, M. Sri Balaji, S. P. Das, Gopal Dubey, Malabika Basu Jan 2002

Regenerative Magnet Load Power Supply With Utility Friendly Operations, M. Sri Balaji, S. P. Das, Gopal Dubey, Malabika Basu

Conference papers

In the present paper, a utility friendly regenerative magnet load power supply has been proposed which can tolerate supply voltage dips and long duration sags or undervoltages and maintains unity input power factor under all operating conditions. The harmonics injected into the utility are much less and the total harmonic distortion (THD) complies with IEEE standards. Unity power factor at the input is maintained by using a synchronous link converter (SLC) as the front-end AC to DC converter with regenerative capability. The two-quadrant chopper in the second stage operates in a constant frequency current control mode and takes care of …


Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle Jan 2002

Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle

Conference papers

While Independent Subspace Analysis provides a means of separating sound sources from a single channel signal, making it an effective tool for drum transcription, it does have a number of problems. Not least of these is that the amount of information required to allow separation of sound sources varies from signal to signal. To overcome this indeterminacy and improve the robustness of transcription an extension of Independent Subspace Analysis to include sub-band processing is proposed. The use of this approach is demonstrated by its application in a simple drum transcription algorithm.


Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer Jan 2002

Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer

Conference papers

An extensive though scattered literature exists on the estimation of time delays in signal processing applications. However, it is possible to identify themes that are common to many of the available techniques. The intention of this paper is to provide a framework against which the literature may be viewed. In addition, original work on gradient based time delay estimation is described.


Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer Jan 2002

Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.