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Articles 991 - 1012 of 1012
Full-Text Articles in Engineering
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Morena Stolfa, Aidan O'Dwyer
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Morena Stolfa, Aidan O'Dwyer
Conference papers
In this paper, we present three different approaches to fit the experimental data of a process with time delay in the time domain. Two of the proposed methods are based on the step response, and the third is based on the pulse response. The effectiveness of these techniques is verified by simulation results and by real-time experimental data. Only first order lag plus time delay models are considered in this paper.
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 1: Parameter Optimised Controllers, Aidan O'Dwyer, John Ringwood
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 1: Parameter Optimised Controllers, Aidan O'Dwyer, John Ringwood
Conference papers
An extensive literature exists on the compensation of time delayed processes. It is possible to identify themes that are common to many of the available techniques. The intention of the two parts of this paper is to provide a framework against which the literature may be viewed; Part 1 of the paper considers the use of parameter optimised controllers for the compensation problem, with Part 2 of the paper considering the use of structurally optimised compensators. Conclusions are drawn at the end of Part 2.
Robust Controller Design For Time Delay Systems Using H-Infinity Techniques, Susan Carr, Aidan O'Dwyer
Robust Controller Design For Time Delay Systems Using H-Infinity Techniques, Susan Carr, Aidan O'Dwyer
Conference papers
Using H-infinity control, the design problem is formulated in terms of user defined weighting polynomials on the process closed-loop sensitivity functions to achieve desired closed-loop performance and robust stability in the presence of process modelling error. In this paper stability conditions , in terms of the process sensitivity functions, are derived for processes containing a pure time delay for the following three design scenarios i) the time delay is neglected in the control design and is considered as part of the unmodelled process dynamics ii) A Pade approximation of the delay is included in the controller design and the effect …
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 …
A Process For Appraising Commerical Usability Evaluation Methods., Ronan Fitzpatrick, Alan Dix
A Process For Appraising Commerical Usability Evaluation Methods., Ronan Fitzpatrick, Alan Dix
Conference papers
Recent international quality standards and European Community legislation have identified new software quality factors. These new factors include suitability, installability and adaptability. Other quality factors need to be reviewed in the light of these developments. This has impacted on established commercial usability evaluation methods to the extent that it is appropriate to ask if these evaluation methods comply with the new standards and legislation. In order to answer this question the commercial evaluation methods need to be appraised (meta-evaluation) using a suitable method appraisal process. This paper describes such an appraisal process which specifically addresses the many considerations raised by …
Fighting Back In Hard Times: The 1990 Strike In Waterford Crystal, Eddie Conlon
Fighting Back In Hard Times: The 1990 Strike In Waterford Crystal, Eddie Conlon
Conference papers
No abstract provided.
Performance And Robustness Issues In The Compensation Of Folpd Processes With Pi And Pid Controllers, Aidan O'Dwyer
Performance And Robustness Issues In The Compensation Of Folpd Processes With Pi And Pid Controllers, Aidan O'Dwyer
Conference papers
This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI and PID controllers whose parameters are specified using appropriate tuning rules. The gain margin, phase margin and maximum sensitivity of the compensated system as the ratio of time delay to time constant of the process varies, are used as ways of judging the performance and robustness of the system.
The Gain Scheduled Piece-Wise Adaptive Digital Control Of A Ph Process, Eugene O'Shaughnessy, Aidan O'Dwyer
The Gain Scheduled Piece-Wise Adaptive Digital Control Of A Ph Process, Eugene O'Shaughnessy, Aidan O'Dwyer
Conference papers
The compensation of a pH process is complicated by the non-linear nature of the process titration curve and the significant time delays that typically exist in such processes. This paper will propose the use of a gain scheduled piecewise adaptive PI controller to compensate the process. A pilot plant is controlled, with the control algorithm implemented on a programmable controller. SCADA software displays and trends the plant and controller signals.
Usable Software And It's Attributes: A Synthesis Of Software Quality: European Community Law And Human-Computer Interaction., Ronan Fitzpatrick, Catherine Higgins
Usable Software And It's Attributes: A Synthesis Of Software Quality: European Community Law And Human-Computer Interaction., Ronan Fitzpatrick, Catherine Higgins
Conference papers
Strategic managers and IS professionals who are responsible for specifying, acquiring and producing quality software products are not supported by the endless flow of new international standards, legislation and user requirements. In order to clarify the current situation for everybody concerned with software quality, and especially those interested in usability, there is a need for a new review and evaluation of the various strands that contribute to software quality. By way of review this paper recalls the original software quality factors which were defined twenty years ago by McCall et al. and presents a methodical analysis and synthesis of three …
A Comparison Of Some Low Cost Laminates For Antennas Operating In The 2.45 Ghz Ism Band, Max Ammann
A Comparison Of Some Low Cost Laminates For Antennas Operating In The 2.45 Ghz Ism Band, Max Ammann
Conference papers
An evaluation of some low-cost laminates suitable for microstrip patch antennas is presented. Criteria for the selection of substrates for antenna fabrication are given careful consideration. A coaxial-probe fed linearly-polarized rectangular microstrip patch operating at a frequency of 2.45 GHz was fabricated on four different low cost laminates. The substrates used were polyester, epoxy glass (FR-4), a ceramic filled PTFE composite and a woven glass-reinforced hydrocarbon and ceramic thermoset material. Material properties are discussed and the antenna performances are evaluated and compared to one fabricated on a thick glass-loaded microfiber PTFE substrate. An evaluation of some inexpensive microstrip antenna CAD …
Compensation Of Processes With Time Delays, Thomas Heeg, Aidan O'Dwyer
Compensation Of Processes With Time Delays, Thomas Heeg, Aidan O'Dwyer
Conference papers
Methods which allow comparisons in the use of PI and PID controller strategies for the control of first order lag plus time delay processes (FOLPD) are worthy of investigation because of the relative lack of work done in this area. In this paper, strategies for comparing performance and robustness for a PI or PID controlled FOLPD process are analysed and designed. The use of different PID controller structures for processes with time delay is also worth considering in detail. Various PID controller structures are compared by means of servo and regulator time responses, Bode plots and Nyquist plots.
The Identification And Control Of Processes With Time Delay, Susan Carr, Aidan O'Dwyer
The Identification And Control Of Processes With Time Delay, Susan Carr, Aidan O'Dwyer
Conference papers
The identification of the frequency response and process model parameters of systems with time delay using frequency domain techniques is evaluated in this paper. The performance of both Fourier Transform and Power Spectral Density techniques is considered. The benefits of employing modern model based design and delay compensation techniques, based on the identified process data, are assessed.
Anatomy Of A Strike: Waterford Glass 1990, Eddie Conlon
Anatomy Of A Strike: Waterford Glass 1990, Eddie Conlon
Conference papers
No abstract provided.
Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood
Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of process parameters and time delay, in a Smith predictor structure, using gradient algorithms in the time domain. A number of estimation algorithms are outlined and applied in simulation to the estimation of the parameters of an appropriate process model. An analytical exploration of the technique is also provided.
The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood
The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood
Conference papers
A modification is proposed to the Smith predictor compensator structure for the control of a process with time delay. The modification facilitates the achievement of an improved closed loop system regulator response, with little degradation in the corresponding servo response. The compensator design procedure is discussed, and simulation results are provided to demonstrate the applicability of the method.
Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood
Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of the parameters (including the time delay) of single input, single output (SISO) process models from an appropriate number of arbitrarily specified points on the process frequency response. The method involves combining an analytical approach with a least squares approach using a gradient algorithm, to provide accurate and robust estimates of the parameters.
Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood
Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood
Conference papers
A number of approaches have been proposed for parameter and time delay estimation of process models in single input, single output (SISO) control systems using gradient descent algorithms; some of these approaches involve the selection of a rational polynomial that is used to approximate time delay variations. This paper takes a generalised approach to the investigation of the most appropriate choice of the rational polynomial, and the gradient descent algorithm, to be used.
An Expert System-Based Approach To Hospitality Company Diagnosis, Andrew Balfe, Peter O'Connor, Ciaran Mcdonnell
An Expert System-Based Approach To Hospitality Company Diagnosis, Andrew Balfe, Peter O'Connor, Ciaran Mcdonnell
Conference papers
This paper describes the development of a prototype Expert System-based Analysis and Diagnostic (ESAD) package for the Hotel and Catering Industry. This computerised tool aids the hospitality manager in methodically scrutinising the hotel unit and environment, combining key information with systematic reasoning. The system searches through its extensive knowledge base, investigating complicated relationships. The number of possibilities considered is increased which will broaden the depth and breadth of the analysis and therefore should improve the quality of the managers decision making.
A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer
A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer
Conference papers
Traditionally, both explicit and implicit self-tuning controllers have employed time domain techniques for the identification and tracking of plant and controller parameters. The use of the frequency domain provides concise information on the dynamics of the process which has led to its wide acceptance as a domain for controller design. This paper demonstrates a method employing recursive, on-line measurement of the process frequency response, with a straightforward calculation of PID controller parameters. The computational effort involved is comparable with that of a time domain technique.
A Comparison Of Techniques For Time Delay Estimation, Aidan O'Dwyer
A Comparison Of Techniques For Time Delay Estimation, Aidan O'Dwyer
Conference papers
This paper reviews some of the techniques used for the identification of unknown lumped time delays in single input, single output (SISO) control systems and evaluates a number of these techniques in simulation and in implementation. Both off line and on line identification techniques are considered.
Standardised Control Techniques For Induction Generators In Both Grid-Connected And Isolated Applications, John Brazil, Aidan O'Dwyer, M. Murphy
Standardised Control Techniques For Induction Generators In Both Grid-Connected And Isolated Applications, John Brazil, Aidan O'Dwyer, M. Murphy
Conference papers
Induction generators are particularly suitable for small hydro applications and are widely used at present. However, with conventional grid-connected techniques, it is not always possible to use them in regions with weak grids because of excessive connection transients. Consequently, their many advantages cannot be fully exploited in these regions. Standardised control systems have been developed by ECS for isolated applications of induction generators and these will now be further developed to permit reduced-transient grid connections.
Fast Discharges In Thin Liquid Layers, Charles J. Frei, Aidan O'Dwyer
Fast Discharges In Thin Liquid Layers, Charles J. Frei, Aidan O'Dwyer
Conference papers
Several mechanisms can be at work when electrical discharges occur across a thin layer of an insulating liquid. The evidence is derived from the time-lag distributions of series of consecutive discharges when the measurements are performed with a sequence of constant voltage pulses.