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Articles 391 - 420 of 438
Full-Text Articles in Electrical and Computer Engineering
Speech-Adaptive Time-Scale Modification For Computer Assisted Language Learning, Olivia Donnellan, Elmar Jung, Eugene Coyle
Speech-Adaptive Time-Scale Modification For Computer Assisted Language Learning, Olivia Donnellan, Elmar Jung, Eugene Coyle
Conference papers
In traditional foreign language learning programmes students are offered a tutor model characterised by slow, deliberate speech. This is insufficient to prepare them to cope with native, colloquial speech. By applying a timescale modification (TSM) algorithm to natural-speed, native speech, students have access to a more desirable, natural speech corpus which permits them to practise essential listening skills in a more focussed manner. This paper presents a method which allows slowing down speech without compromising the quality, pitch or naturalness of the slowed speech by applying different scaling factors to different types of speech segments. The new method is compared …
Quality Challenges In E-Commerce Websites, Ronan Fitzpatrick
Quality Challenges In E-Commerce Websites, Ronan Fitzpatrick
Conference papers
No abstract provided.
Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer
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.
Closed Loop Identification Of A First Order Plus Dead Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
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 …
Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer
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 Dermot Coyle Professor
Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
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.
Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
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 …
Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer
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.
Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See
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.
Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle
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.
Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Dermot Coyle Professor
Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Dermot Coyle Professor
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 Dermot Coyle Professor
A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
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 …
Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer
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.
Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer
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.
Regenerative Magnet Load Power Supply With Utility Friendly Operations, M. Sri Balaji, S. P. Das, Gopal Dubey, Malabika Basu
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 …
A Wideband Monopole For Reconfigurable Multiband Radio Terminals, Max Ammann
A Wideband Monopole For Reconfigurable Multiband Radio Terminals, Max Ammann
Conference papers
A wideband planar monopole employing two broadbanding techniques is investigated, and is shown to yield an impedance bandwidth ratio of 10:1 or greater for a return loss of 8 dB. The radiation pattern bandwidth is also investigated
Experimental Investigation Of Performance Of A Single Phase Upqc For Voltage Sensitive And Non-Linear Loads, Malabika Basu, S. P. Das, Gopal K. Dubey
Experimental Investigation Of Performance Of A Single Phase Upqc For Voltage Sensitive And Non-Linear Loads, Malabika Basu, S. P. Das, Gopal K. Dubey
Conference papers
A unified power quality conditioner (UPQC) is proposed in this paper. It protects the consumer at the load end from supply voltage sag, and provides unity power factor condition at the utility for different values of load power factor. A PC-based closed loop control scheme is proposed and experimental investigation is carried out in the laboratory. Selected experimental results are reported along with control circuit and phasor diagram to validate the proposition.
Comparison Of Two B-Polynomial Methods: Application To The Identification Of Time Delayed Processes, Ruiyao Gao, Aidan O'Dwyer
Comparison Of Two B-Polynomial Methods: Application To The Identification Of Time Delayed Processes, Ruiyao Gao, Aidan O'Dwyer
Conference papers
An extensive literature exists on the estimation of the model parameters of time delayed processes. The objective of this paper is to review the main B-polynomial approaches to the delay estimation problem. More specifically, two algorithms are discussed and compared theoretically and in simulation. The algorithms involve various procedures to assess how the model relates to the observed data, to a priori knowledge, and to the algorithms’ intended use. Simulation results indicate that both the algorithms can suitably identify the model parameters, including the time delay. This paper also discusses advantages and disadvantages of the methods and gives some guidelines …
Pi And Pid Controller Tuning Rule Design For Processes With Delay, To Achieve Constant Gain And Phase Margins For All Values Of Delay, Aidan O'Dwyer
Pi And Pid Controller Tuning Rule Design For Processes With Delay, To Achieve Constant Gain And Phase Margins For All Values Of Delay, Aidan O'Dwyer
Conference papers
This paper will discuss the design of PI and PID controller tuning rules to compensate processes with delay, that are modelled in a number of ways. The rules allow the achievement of constant gain and phase margins as the delay varies.
A Wideband Monopole For Reconfigurable Multiband Radio Terminals, Max Ammann
A Wideband Monopole For Reconfigurable Multiband Radio Terminals, Max Ammann
Conference papers
A wideband planar monopole employing two broadbanding techniques is investigated, and is shown to yield an impedance bandwidth ratio of 10:1 or greater for a return loss of 8 dB. The radiation pattern bandwidth is also investigated
Small Planar Monopole Covers Multiband Brans, Max Ammann, L. E. Doyle
Small Planar Monopole Covers Multiband Brans, Max Ammann, L. E. Doyle
Conference papers
The use of a single antenna which can cover a wide range of frequencies is a desirable feature for future wireless communications systems. The emerging self-organising and ad-hoc networks require more than an octave of bandwidth to facilitate multiband operation. A shorted planar monopole antenna is optimised for future wireless networking bands by suitable choice of planar dimension and feedgap separation. The antenna offers a return-loss greater than 10 dB from 1.60 GHz to 5.90 GHz. The radiation pattern is shown to be quasi-omnidirectional within the 10 dB return-loss bandwidth. Antenna properties are compared with the simple planar monopole.
Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer
Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer
Conference papers
This paper will compare a number of PID and predictive controller strategies to compensate processes modelled in first order lag plus time delay (FOLPD) form. The performance and robustness of the resulting compensated systems are evaluated analytically (where appropriate) and in simulation.
Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer
Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer
Conference papers
An extensive literature exists on the PID compensation of time delayed processes. It is possible to identify themes that are common to many of the available techniques. The intention of the paper is to provide a framework against which the literature may be viewed.
Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood
Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of the parameters of a single input, single output (SISO) process, modelled in first order lag plus delay (FOLPD) form, using gradient methods in the open loop time domain. The paper considers the convergence of the process parameters to the model parameters. The convergence of the model delay is discussed first, when the non-delay model and process parameters are identical. The convergence of all of the model parameters is then considered, when all of the process parameters are unknown.
Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp
Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp
Conference papers
Wet and dry oxidations of (111) crystalline silicon wafers were performed at temperatures between 900°C and 1150°C and subsequently annealed at 700°C. Process parameters such as the withdrawal rate from the furnace and annealing time were varied and the effect on the oxide layer are discussed. The magnitude and nature of the stress in the wafers after thermal oxidation was analysed using micro-Raman spectroscopy. The Full Width at Half Maximum (FWHM) of the Raman peak at ~ 520 cm-1 was also analysed to extract information relating to crystal disorder and defect density caused by the oxidation process. The results obtained …
Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer
Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer
Conference papers
An extensive though scattered literature exists on the estimation of the model parameters of time delayed processes. However, it is possible to identify themes that are common to many of the proposed techniques. The intention of this paper is to provide a framework against which the literature may be viewed.
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer
Conference papers
The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PI control of single input, single output (SISO) processes with time delay is provided in this paper.
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
Conference papers
The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PID control of single input, single output (SISO) processes with time delay is provided in this paper.
Additional Quality Factors For The World Wide Web., Ronan Fitzpatrick
Additional Quality Factors For The World Wide Web., Ronan Fitzpatrick
Conference papers
Web site development is maturing from the enthusiastic experimental practice of early years to a more professional discipline, addressing the needs of Web site visitors and owner organisations. Quality is central to this maturing and it is necessary to have a full understanding of the meaning of quality in the context of the ever-changing Web. This paper identifies five new quality factors for the Web (visibility, credibility, intelligibility, engagibility and differentiation), together with their characteristics and a checklist of enablers, which can be used by specifiers, designers, developers and evaluators to create quality Web sites.
Square Planar Monopole Antenna, Max Ammann
Square Planar Monopole Antenna, Max Ammann
Conference papers
A planar monopole may be realised by replacing the wire element of a conventional monopole with a planar element. In this case, the planar element which is square, is located above a groundplane and fed using an SMA connector as illustrated. The square monopole has a simple geometry and a smaller bandwidth compared to the circular-disc monopole. However, it is still a broadband antenna with a typical impedance bandwidth of 75 % at S band. This broadband antenna shows a constant radiation pattern over the impedance bandwidth. A simple formula for the frequency corresponding to the lower edge of the …