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Articles 1 - 23 of 23
Full-Text Articles in Engineering
Performance Evaluation Of Video Streaming With Background Traffic Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Performance Evaluation Of Video Streaming With Background Traffic Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Conference papers
There is an increasing demand for multimedia streaming applications over WLAN networks. MPEG-4 and H.264 are compression standards targeted at high-quality streamed multimedia services over wireless best-effort IP networks. However, the dynamic nature of wireless networks in terms of fluctuating bandwidth and time-varying delays makes it difficult to provide good quality streaming under such constraints. Multimedia streaming applications are a demanding and challenging service to deliver over wireless networks. There is a trade-off between the capacity of the wireless network and the quality of the multimedia streaming application. In this paper we investigate the effect the background traffic load has …
Performance Evaluation Of Resource Usage For Unicast Video Streaming Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Performance Evaluation Of Resource Usage For Unicast Video Streaming Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Conference papers
Multimedia streaming applications are a demanding and challenging service to deliver over wireless networks. Such services have a large impact on the resource requirements of the WLAN. However, there are many variables involved in video streaming, such as the video content being streamed, how the video is encoded and how it is sent. This makes the role of radio resource management and the provision of QoS guarantees extremely difficult. In this paper we investigate the network resource requirements for three scenarios: a single unicast video streaming session; multiple unicast video streaming sessions and finally multiple unicast streaming sessions in the …
An Assessment Of The Audio Codec Performance In Voice Over Wlan (Vowlan) Systems, Miroslaw Narbutt, Mark Davis
An Assessment Of The Audio Codec Performance In Voice Over Wlan (Vowlan) Systems, Miroslaw Narbutt, Mark Davis
Conference papers
In this paper we present results of experimental investigation into the performance of three audio codecs (ITU-T G.711, G.723.1 and G.729A) under varying load conditions on a Voice over WLAN system utilizing the IEEE 802.11b wireless LAN standard. The analysis is based upon a new technique for estimating user satisfaction of speech quality calculated from packet delay and packet loss/late measurements. We also demonstrate the importance of the de-jitter buffer playout scheme for insuring speech quality. From our results we conclude that the use of the G.711 audio codec in conjunction with the new adaptive playout scheme gives the highest …
Assessing The Quality Of Voip Transmission Affected By Playout Buffer Scheme, Miroslaw Narbutt, Mark Davis
Assessing The Quality Of Voip Transmission Affected By Playout Buffer Scheme, Miroslaw Narbutt, Mark Davis
Conference papers
Delay, echo, encoding scheme, and packet loss all influence perceived quality of conversational speech transmitted over packet networks. Therefore, the choice of a buffer algorithm cannot be solely based on statistical loss/delay trade-off metrics. Also subjective “listening tests” or the newer ITU-T PESQ method, which don’t consider the effect of mouth-to-ear delay are inappropriate. We proposed a method for assessing VoIP call quality by extending the ITU-T E-model concept. This method provides a direct link to perceived conversational speech quality by estimating user satisfaction from the combined effect of information loss, delay and echo.
Multi-Channel Audio Time-Scale Modification, David Dorran, Robert Lawlor, Eugene Coyle
Multi-Channel Audio Time-Scale Modification, David Dorran, Robert Lawlor, Eugene Coyle
Conference papers
Phase vecoder based approaches to audio time-scale modification introduce a reverberant artefact into the time scaled output. Recent techniques have been developed to reduce the presence of this artefact; however, these techniques have the effect of introducing additional issues relating to their application to multi-channel recordings. This paper addresses these issues by collectively analysing all channels prior to time-scaling each individual channel.
A Novel Framework For Radio Resource Management In Ieee 802.11 Wireless Lans, Mark Davis, Tristan Raimondi
A Novel Framework For Radio Resource Management In Ieee 802.11 Wireless Lans, Mark Davis, Tristan Raimondi
Conference papers
In this paper we address the need to characterize and quantify resource usage in IEEE 802.11 WLANs in order to support radio resource management. We present a compact and intuitive framework for performance characterization and resource utilization that is based upon the concept of MAC bandwidth components. These MAC bandwidth components are directly related to the transmission rate and serve to quantify the resource requirements associated with accessing the wireless medium. We also introduce a graphical technique for presenting these MAC bandwidth components that illustrates how WLAN stations interact in contending for access to the wireless medium. We demonstrate the …
Performance Analysis Of Network-Level Qos With Encoding Configuration For Unicast Video Streaming Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Performance Analysis Of Network-Level Qos With Encoding Configuration For Unicast Video Streaming Over Ieee 802.11 Wlan Networks, Nicola Cranley, Mark Davis
Conference papers
Video streaming has a large impact on the resource requirements of the WLAN. However, there are many variables involved in video streaming, such as the video content being streamed, how the video is encoded and how it is sent. This makes the role of radio resource management extremely difficult. In this paper we investigate the effect that video encoding configurations has on the network resource requirements for unicast video streaming in a WLAN environment. We compare the network resource requirements of several content types encoded at various encoding configurations with varying I-frame frequencies, target encoding bit rates and hint track …
Onset Detection, Music Transcription And Ornament Detection For The The Traditional Irish Fiddle, Aileen Kelleher, Derry Fitzgerald, Eugene Coyle, Robert Lawlor, Mikel Gainza
Onset Detection, Music Transcription And Ornament Detection For The The Traditional Irish Fiddle, Aileen Kelleher, Derry Fitzgerald, Eugene Coyle, Robert Lawlor, Mikel Gainza
Conference papers
By combining techniques used in previous onset detectors, a system that detects note onsets in traditional Irish fiddle tunes has been implemented. The notes detected also include the most common types of ornamentation played by the fiddle. Ornaments are notes of extremely short duration, at most a fifth the length of a regular note. A Short Time Fourier Transform based sub-band technique, which previously gave good results for the Irish tin whistle, was modified to include a threshold approximation more suitable for the fiddle. This system has been tested on a database of real recorded fiddle tunes and good results …
Development Of A Computer-Based Violin Teaching Aid: Vitool, Jane Charles, Derry Fitzgerald, Eugene Coyle
Development Of A Computer-Based Violin Teaching Aid: Vitool, Jane Charles, Derry Fitzgerald, Eugene Coyle
Conference papers
This paper considers the development of a violin teaching aid, called ViTool, which is based on violin pedagogy, sound analysis, and comparison of beginner and good player recordings. It is a computer based teaching aid and will ultimately consist of at least four task dependent tools. Typical beginner faults have been identified and features, that best describe them for classification purposes, are considered. The ViTool is not intended as a replacement or electronic teacher, but as a teaching aid. Presently, it seems that no such violin learning aid or tool exists and an opportunity exists for the development of such …
Single Channel Source Separation Using Short-Time Independent Component Analysis, Dan Barry, Derry Fitzgerald, Eugene Coyle
Single Channel Source Separation Using Short-Time Independent Component Analysis, Dan Barry, Derry Fitzgerald, Eugene Coyle
Conference papers
In this paper we develop a method for the sound source separation of single channel mixtures using Independent Component Analysis within a time-frequency representation of the audio signal. We apply standard Independent Component Analysis techniques to contiguous magnitude frames of the short-time Fourier transform of the mixture. Provided that the amplitude envelopes of each source are sufficiently different, it can be seen that it is possible to recover the independent short-time power spectra of each source. A simple scoring scheme based on auditory scene analysis cues is then used to overcome the source ordering problem ultimately allowing each of the …
Non-Negative Tensor Factorisation For Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Non-Negative Tensor Factorisation For Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Conference papers
An algorithm for Non-negative Tensor Factorisation is introduced which extends current matrix factorisation techniques to deal with tensors. The effectiveness of the algorithm is then demonstrated through tests on synthetic data. The algorithm is then employed as a means of performing sound source separation on two channel mixtures, and the separation capabilities of the algorithm demonstrated on a two channel mixture containing saxophone, strings and bass guitar.
A Reference Guide To Smith Predictor Based Methods For The Compensation Of Dead-Time Processes, Aidan O'Dwyer
A Reference Guide To Smith Predictor Based Methods For The Compensation Of Dead-Time Processes, Aidan O'Dwyer
Conference papers
An extensive literature exists on the compensation of time delayed processes. These compensation methods may be broadly divided into parameter optimised controllers, in which the controller parameters are adapted to the controller structure (the most common such controller is the proportional integral derivative, or PID, controller), and structurally optimised controllers, in which the controller structure and parameters are adapted optimally to the structure and parameters of the process model. Important structurally optimised compensator strategies are the Smith predictor and its variations. The purpose of this paper is to extract the essence of the developments in design, tuning and implementation of …
Pid Controller Tuning Of Networked Computer Based Control Systems, Aidan O'Dwyer
Pid Controller Tuning Of Networked Computer Based Control Systems, Aidan O'Dwyer
Conference papers
This contribution discusses the use of PID controller tuning rules to assist in the implementation of network computer based control systems. Such systems typically have a variable time delay associated with the transfer of information. PID controller tuning rules can be directly implemented with minimal capital investment.
Dual-Band Monopole Antenna With Stagger-Tuned Arms For Broadbanding, Max Ammann, R. Farrell
Dual-Band Monopole Antenna With Stagger-Tuned Arms For Broadbanding, Max Ammann, R. Farrell
Conference papers
The paper describes a dual-band miniaturized printed monopole for integration in modern wireless systems. The printed monopole is augmented with two arms, resonant at slightly different frequencies, providing a broadened response for the upper band. The achieved bandwidth for the high band is 36%. These antennas are proposed for the emerging dual-mode multi-band WLAN transceivers, which operate over a wide range of bands as dictated by national authorities. Measured and simulated data, including return loss, antenna gain and radiation patterns, are presented. The numerical method employed was the finite integration technique.
Comparative Study Of Two Techniques For Determining Critical Frequency Response Characteristics, Niall O'Connor, Aidan O'Dwyer
Comparative Study Of Two Techniques For Determining Critical Frequency Response Characteristics, Niall O'Connor, Aidan O'Dwyer
Conference papers
The paper presents a review of a comparative study of two separate techniques for obtaining important frequency and time domain characteristics of a system consisting of a process in series with a PI/PID controller in closed loop. The first technique involves the use of a Pseudo Random Binary Sequence (PRBS) to obtain the closed loop frequency response of the system. This closed loop frequency information may then be manipulated to obtain both open loop frequency response information and process model parameters. A further mathematical simulation using Matlab may then be performed independent of the actual process in order to obtain …
Smith Predictor Structure Stability Analysis Using Mikhailov Stability Criterion, Pauline Sourdille, Aidan O'Dwyer, Eugene Coyle
Smith Predictor Structure Stability Analysis Using Mikhailov Stability Criterion, Pauline Sourdille, Aidan O'Dwyer, Eugene Coyle
Conference papers
As is well known, stability is an important requirement for control systems. Due to the nature of time-delay processes, common methods to evaluate stability may be difficult to use. In 1938, Mikhailov proved a frequency response criterion, which is sufficient and necessary for the stability of processes described by known n-th order constant coefficient linear differential equations. This paper presents the Mikhailov method and the application of this method to a Smith predictor structure controlled by a PI controller.
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Yue Zhang, Aidan O'Dwyer
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Yue Zhang, Aidan O'Dwyer
Conference papers
All process investigations should start by a determination of the process model. The modeling strategy used will influence the value of the model parameters, which will in turn affect the controller values determined from tuning rules. This paper will describe an analytical method to identify a model of the dynamic characteristics of a process with a delay by using a tangent and point method, as originally suggested by Murrill, 1967. The methodology has been applied to eight benchmark transfer functions suitable for testing PID controllers, as suggested by Åström and Hägglund, 2000. The main advantages of the modeling approach are …
Modelling And Control Of A Suspension System For Vehicle Applications, Padraig Dowds, Aidan O'Dwyer
Modelling And Control Of A Suspension System For Vehicle Applications, Padraig Dowds, Aidan O'Dwyer
Conference papers
This paper discusses the modelling of passive and active suspension systems in a car, and the subsequent design of appropriate feedback controllers for the active suspension system. The models will be investigated using a quarter car model and a full car model approach.
A New Architecture For A Multi Polarized Perpendicularly-Fed Radiating Element, Naftali Herscovici, Francisco Lerma, Max Ammann
A New Architecture For A Multi Polarized Perpendicularly-Fed Radiating Element, Naftali Herscovici, Francisco Lerma, Max Ammann
Conference papers
Planar printed antennas are often required to be fed by parallel feed-networks, which, when printed on the same substrate as the radiating elements, create mutual coupling, spurious radiation and excite surface waves. This considerably affects the array efficiency. Numerous architectures were proposed in the past; some of them use the multilayer structure (which by itself exhibits low efficiency), or perpendicularly fed structures. The latter consist of a substrate for the radiating element and another substrate which for the feed-network. The paper reviews some of the basic configurations proposed until now, and shows the specific improvements introduced by the proposed architecture.
Pid Control: The Early Years, Aidan O'Dwyer
Pid Control: The Early Years, Aidan O'Dwyer
Conference papers
This contribution outlines controller developments 1788 – c.1900; 1900-1950: The role of instrument companies; early theoretical description of the PID controller; early tuning of the PID controller; some further developments since 1950; some conclusions.
Design Of A Wireless System For Patient-Hospital Communciation And Result Validation In Point Of Care Testing, John Mcgrory, Owen Lynch, Eugene Coyle
Design Of A Wireless System For Patient-Hospital Communciation And Result Validation In Point Of Care Testing, John Mcgrory, Owen Lynch, Eugene Coyle
Conference papers
This paper discuses mobile phone (cell phone) and wireless applications for linking patients who manage their healthcare outside the hospital using point of care testing (POCT) to hospital information systems (HIS). Certain medical conditions require patients to manage their healthcare by performing on themselves POC testing and act faithfully on the result. This raises quality control issue, as these POC samples and testing procedures are not independently overseen by professional hospital staff. In hospitals, samples taken by clinicians are validated by hi-tech computerised validation systems to ensure plausibility, before physicians rely on them. Patients in the home must often use …
Maintaining A Balance At Undergraduate Degree Level In The Teaching Of Automation And Classical Control Systems, Eugene Coyle, Aidan O'Dwyer
Maintaining A Balance At Undergraduate Degree Level In The Teaching Of Automation And Classical Control Systems, Eugene Coyle, Aidan O'Dwyer
Conference papers
Advances in the past decade in the development and application of Programmable Logic Controllers (PLCs) and Automation Systems in both high technology industrial plants and in the more mainstream manufacturing sectors, has heightened the importance of ensuring that undergraduate degree programme syllabi are designed to adequately cater for the teaching and training of students in automation. Prior to this growth in automation, delivered syllabi in Control Systems on most Electrical Engineering programmes had a theoretical rigour, reflecting the mathematical nature of the topic. A major challenge currently facing departmental lecturing staff and programme coordinators is that of the design of …
Learning Games Programming With Dalek World., Bryan Duggan, Hugh Mcatamney, Fredrick Mtenzi
Learning Games Programming With Dalek World., Bryan Duggan, Hugh Mcatamney, Fredrick Mtenzi
Conference papers
From September 2005 the School of Computing in the DIT will offer an elective in computer games programming to final year computer science students. This paper demonstrates how students will learn games programming by developing a 3D FPS (First Person Shooter) called Dalek World. Dalek World is developed using Microsoft Visual Studio in C++ and was originally developed by the authors to learn games programming techniques themselves. In developing Dalek World, students will learn Euclidian geometry, 3D graphics programming, object orientated game design, level loading, physics, collision detection, the A* algorithm, perception and enemy AI using finite state machines.