Engineering Commons^™

Meshscan: A Fast And Efficient Handoff Scheme For Ieee 802.11 Wireless Mesh Networks, Yin Chen

Masters

As a next generation network solution, Wireless Mesh Networks (WMN) provides fast Internet access to a large area, which is from university campus to city scale. In order to provide an uninterrupted Internet experience to a mobile client, a process called handoff is required to maintain the network connection from one Mesh Node (MN) to another MN. Ideally, handoff should be completely transparent to mobile users. A critical application like VoIP will require a handoff capability that transfers a call from one mesh node (MN) to another in less than 50 msec. However the current IEEE 802.11 standards do not …

Reconfigurable Antenna With Elevation And Azimuth Beam Switching, S. Shynu, Max Ammann

Articles

A reconfigurable microstrip antenna is proposed for low-cost adaptive beam-switching applications. A small patch-slot-ring structure is used as the radiating element where an asymmetrical arrangement of p-i-n diodes is employed to switch the pattern in four directions. The antenna provides pattern switching of 65° and 45° in its fundamental mode for the elevation and azimuth planes, respectively. By maintaining the resonant frequency and beamwidth as relatively constant, beam switching is realized using a single feed point.

Input-Output Analysis Of Irish Construction Sector Greenhouse Gas Emissions, Adolf Acquaye, Aidan Duffy

Articles

Ireland is committed to limiting its greenhouse gas (GHG) emissions to 113% of 1990 levels over the period 2008-12 and to 84% of 2005 levels by 2020 under the Kyoto Agreement and the EU’s ’20 20’ by 2020 respectively. National policies have targeted many industry sectors but have failed to directly tackle GHG emissions associated with construction activity. This paper estimates energy and GHG emissions intensities of the Irish construction sector and subsectors and estimates its contribution to Irish national emissions. This information is used to identify and assess the impacts of policy measures which would result in a reduction …

Power Quality In Grid Connected Renewable Energy Systems: Role Of Custom Power Devices, Shafiuzzaman Khan Khadem, Malabika Basu, Michael Conlon

Conference papers

This paper deals with the technical review of power quality problems associated with the renewable based distributed generation systems and how the custom power devices like STATCOM, DVR and UPQC play important role in power quality improvement. IEEE and IEC standard for the grid connected renewable energy systems are one of the critical point of interest for the selection of custom power devices. Special attention has been given on the compensation of reactive power, harmonic current and voltage fluctuation during the interconnected as well as islanding mode of operation. As the solar and wind are the most abundant resources therefore …

The Control Of Rotor Side And Grid Side Converters In A Dfig During Network Voltage Unbalance Conditions Using Resonant Current Controllers., Joseph Kearney, Michael Conlon, Eugene Coyle

Conference papers

This paper implements control techniques to enable improved operation of DFIG’s when subjected to the effects of network voltage unbalance conditions. The control scheme involves the integration of a resonant regulator into the PI controllers of both the rotor side and grid side converters in a DFIG. The resonant controller is tuned to twice the network frequency (2ω_e) and designed to mitigate against the oscillations in a DFIG due to network voltage unbalance conditions. The grid side converter controller also incorporates a second resonant controller tuned to three times the grid frequency (3ω_e) to alleviate the …

Measuring Variations Of Mimicry By Means Of Prosodic Cues In Task-Based Scenarios And Conversational Speech, Brian Vaughan, Celine De Looze

Other resources

Here, we address the measurement of mimicry, that is when speakers’ speech variations look like parallel patterns.

As a definition of mimicry, we often read in the literature description such as mimicry is “The situation where the observed behaviours of two inter-actants although dissimilar at the start of the interaction are moving towards behavioral matching”. These types of descriptions imply that mimicry is a linear phenomenon and that speakers tend to imitate over time. However, it can be assumed, especially when studying spontaneous speech, that there are rather phases of mimicry and non-mimicry and that mimicry should be rather …

Evidence Based Evaluation Research In Engineering, Kevin Kelly

Other resources

No abstract provided.

Novel Ac Side P&O Maximum Power Transfer Control For Grid Connected Photovoltaic Systems, Mohamed Moin Hanif, Malabika Basu, Kevin Gaughan

Conference papers

Grid connected Photovoltaic inverters can convert PV energy into electricity with very high efficiencies. Power from the PV panels fluctuates depending on various weather conditions. PV inverters usually include a maximum power point tracker (MPPT) to track this varying power, in order to transfer all the available power to the grid efficiently. Control of power transferred to the grid along with the MPPT plays a crucial role in determining the efficiency of a PV system. This paper discusses about the basic power transfer theory between sources (PV and Grid) and focuses on the need of a DC-DC boost circuit, along …

Miniature Ceramic Pifa For Uwb Band Group 3 And 6, David Kearney, Matthias John, Max Ammann

Articles

A ceramic chip planar inverted-F antenna (PIFA) is proposed for integration into a mobile handset providing UWB functionality across band groups 3 and 6. The antenna design exhibits a total efficiency of greater than 50% across the entire 6.39 GHz bandwidth while maintaining a very small volume of 57.6 mm^3 . The antenna uses a combination of the normal PIFA resonance and a second resonance due to the ceramic block to achieve a broad ultrawideband (UWB) bandwidth.

Thermal Robotic Arm Controlled Spraying Via Robotic Arm And Vision System, Dermot Breen

Doctoral

The Tribology Surface Engineering industry is a worldwide multi billion euro industry with significant health and safety risks. The thermal spraying sector of this industry employs the technique of applying molten surface coating material to a substrate via a thermal spray process which is implemented either by manual spraying or pre-programmed robotic systems. The development of autonomous robotic systems for thermal spraying surface coating would significantly improve production and profitability over pre-programmed systems and improve health and safety over manual spraying. The aim of this research was to investigate and develop through software simulation, physical modelling and testing the development …

Spontaneous Periodic Deformations In Nonchiral Planar-Aligned Bimesogens With A Nematic-Nematic Transition And A Negative Elastic Constant, V. P. Panov, J. K. Vij, Yuri Panarin, A. Kohlmeier, M. G. Tamba, R. A. Lewis, G. H. Mehl

Articles

Hydrocarbon linked mesogenic dimers are found to exhibit an additional nematic phase below the conventional uniaxial nematic phase as confirmed by x-ray diffraction. The phase produces unusual periodic stripe domains in planar cells. The stripes are found to be parallel to the rubbing direction (in rubbed cells) with a well-defined period equal to double the cell gap. The stripes appear without external electromagnetic field, temperature or thickness gradients, rubbing or hybrid alignment treatments. Simple modeling proposes a negative sign for at least one of the two elastic constants: splay and twist, as a necessary condition for the observed pattern.

Blind Single Channel Sound Source Separation, Mark Leddy

Masters

In recent years source separation has become an increasingly popular area of research in the signal processing community. The subject has found applications in a variety of fields such as medical imaging, sound and audio, econometrics and geophysics. This document will discuss the application of source separation techniques to the area of audio. Sound source separation is the process of observing a mixture signal made up of a number of sources, and from this mixture estimating the individual source signals. Audio source separation techniques may be crudely split into the following areas; techniques that utilise attributes of the sources, and …

Single Channel Vocal Separation Using Median Filtering And Factorisation Techniques, Derry Fitzgerald, Mikel Gainza

Articles

This paper deals with the problem of the extraction of vocals from single channel audio signals containing both vocals and other instruments, including both pitched instruments and percussion instruments. A novel median filtering-based approach for the extraction of vocal tracks is described, which is simple and efficient to implement. Further improvements in separation quality are then obtained by the application of tensor factorisation techniques to further extract residual instruments from the vocal mix. Finally, a novel use of non-negative partial matrix cofactorisation is demonstrated as a means of further improving separation quality. Here the original single channel mixture is partially …

Locating Tune Changes And Providing A Semantic Labelling Of Sets Of Irish Traditional Tunes, Cillian Kelly, Mikel Gainza, David Dorran, Eugene Coyle

Conference papers

An approach is presented which provides the tune change loactions within a set of Irish traditional turnes. Also provided are semantic labels for each part of each tune within the set. A set in Irish traditional music is a number of individual tunes played segue. Each of the tunes in the set are made up of structural segments called parts. Musical variation is a prominent characteristic of this genre. However, a certain set of notes known as "set accented tones" are considered impervious to musical variation. Chroma information is extracted at "set accented tone" locations within the music. The resulting …

Exploiting Glottal Formant Parameters For Glottal Inverse Filtering And Parameterization, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

It is crucial for many methods of inverse filtering that the time domain information of the glottal source waveform is known, e.g. the location of the instant of glottal closure. It is often the case that this information is unknown and/or cannot be determined due to e.g. recording conditions which can corrupt the phase spectrum. In these scenarios, alternative strategies are required. This paper describes a method which, given the parameters of the glottal formant of the signal frame, can accurately parameterize the glottal shape source and vocal filter for a broad range of voice quality types and which is …

Harmonic/Percussive Separation Using Median Filtering, Derry Fitzgerald

Conference papers

In this paper, we present a fast, simple and effective method to separate the harmonic and percussive parts of a monaural audio signal.The technique involves the use of median filtering on a spectrogram of the audio signal, with median filtering performed across successive frames to suppress percussive events and enhance harmonic components, while median filtering is also performed across frequency bins to enhance percussive events and supress harmonic components. The two resulting median filtered spectrograms are then used to generate masks which are then applied to the original spectrogram to separate the harmonic and percussive parts of the signal. We …

Interactive Music Archive Access System, Martin Gallagher, Derry Fitzgerald, Dan Barry, Matt Cranitch, Eugene Coyle

Conference papers

The goal of the Interactive Music Archive Access System (IMAAS) project was to develop an interactive music archive access system which was capable of allowing an end-user to easily extract rhythmic, melodic and harmonic musical metadata descriptors from audio, and allow the user to interact with the archive contents in a manner not typically allowed in archive access systems. To this end, the IMAAS system incorporates a range of real-time interaction tools which allow the user to modify the retrieved audio in a number of ways including the ability to isolate individual instruments in stereo mixes, pitch and time-scale modification, …

Protection Of Upqc Against The Load Side Short Circuits, Iurie Axente, Malabika Basu, Michael Conlon, Kevin Gaughan

Articles

This study presents a protection scheme for protecting the series inverter of a unified power quality conditioner (UPQC). The proposed scheme protects the series inverter from overcurrents and overvoltages, which appear during short-circuit faults on the load side of the UPQC. The main protection element is a crowbar connected across the secondary of the series transformer and consists of a pair of antiparallel connected thyristors, which is governed by a simple Zener diode-based control circuit. In the case of an overvoltage, the crowbar short circuits the secondary of the transformer, thus removing the overvoltage and diverting the fault current from …

Feasibility Of Using Passive Monitoring Techniques In Mesh Networks For The Support Of Routing, Chenzhe Zhang

Masters

In recent years, Wireless Mesh Networks (WMNs) have emerged as a promising solution to provide low cost access networks that extend Internet access and other networking services. Mesh routers form the backbone connectivity through cooperative routing in an often unstable wireless medium. Therefore, the techniques used to monitor and manage the performance of the wireless network are expected to play a significant role in providing the necessary performance metrics to help optimize the link performance in WMNs. This thesis initially presents an assessment of the correlation between passive monitoring and active probing techniques used for link performance measurement in single …

Development Of A Quality Of Service Framework For Multimedia Streaming Applications, Stuart Wallace

Masters

By the year 2012, it is expected that the majority of all Internet traffic will be video content. Coupled with this is the increasing availability of Wireless Local Area Networks (WLANs) due to their ease of deployment, flexibility and reducing roll out costs. Unfortunately the contention based access mechanism utilised by IEEE 802.11 WLANs does not suit the non-uniform or bursty bandwidth profile of a video stream which can lead to a reduced quality of service (QoS) being experienced by the end-user. In 2005, the IEEE 802.11e protocol was ratified in an attempt to solve this emerging problem. It provides …

The Effects Of Harmonics On Power Quality And Energy Efficiency, Alan Harrison

Other resources

By making our electricity supply more secure, reliable and versatile will mean that we reduce our reliance upon oil, gas and solid fuels, which mostly exist outside of Ireland and the European community. The majority of our fuel is imported and this makes our economy dependent on outside interests and out of our control. Even more importantly as the world’s fossil fuel reserves are running out and electricity demand is ever increasing.

If we make our electricity networks secure and designed to the highest standards we can import and export electrical energy more easily as our demands change, for example …

Connecting Micro-Generators In Parallel To The Low Voltage Distribution Network Utilising Standard En50438 In The Republic Of Ireland, Liam Murphy

Other resources

The green agenda has been much to the fore internationally and has particularly had an influence in Republic of Ireland (ROI) where there are ‘green’ ministers in Government. Mr. Eamon Ryan who is the Minister for Communications, Energy and Natural Resources has particularly championed the idea of self generation. The author’s interest in the subject matter is to investigate the up-take of micro-generation and determine the likely short term future along with the grid tie standard i.e. EN50438.

Issues surrounding micro-generation are considered from the international and national perspective and from a customer and generation utility point of view. The …

A Hybrid Fiber Optic Sensing System For Simultaneous Strain And Temperature Measurement And Its Application, Ginu Rajan, Karolina Milenko, Piotr Lesiak, Yuliya Semenova, Anna Boczkowska, Manjusha Ramakrishnan, Kazimierz Jedrzejewski, Andrzej Domanski, Tomasz Wolinski, Gerald Farrell

Articles

A hybrid fiber optic sensor by integrating polarimetric fiber sensors and fiber Bragg grating sensors for simultaneous strain and temperature measurement is presented in this paper. Two types of polarimetric fiber sensors are used; a Panda fiber and a polarization maintaining photonic crystal fiber. The polarimetric strain sensors give the average strain and temperature information, while the fiber Bragg grating sensors give localized strain information. Two applications of the proposed configuration are also demonstrated in this paper. In the composite materials three fiber sensors are used while for other engineering applications a temperature insensitive polarimetric fiber sensor can be used …

A Macrobending Singlemode Fiber Refractive Index Sensor For Low Refractive Index Liquids, Pengfei Wang, Yuliya Semenova, Yong Li, Qiang Wu, Gerald Farrell

Articles

An all-fiber refractive index sensor with a simple configuration is proposed and investigated. The proposed fiber refractometer consists of a full-loop structure of bare high-bend loss singlemode fiber-1060XP, employing the well-known whispering gallery mode (WGM) effect induced by the evanescent wave excitation to measure the refractive index of an external medium. A competitive sensitivity is achieved (average 725.76nm/RIU at a bend diameter of 19.3mm) compared with other fiber-optic sensors, plus benefits resulting from simplicity, low cost and ease of fabrication.

Experimental Demonstration Of A Simple Displacement Sensor Based On A Bent Singlemode-Multimode-Singlemode (Sms) Fiber Structure, Qiang Wu, Yuliya Semenova, Pengfei Wang, Agus Hatta, Gerald Farrell

Articles

A simple displacement sensor based on a bent singlemode-multimode-singlemode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 μm; (2) if interrogated by a …

A Liquid Crystal Coated Tapered Photonic Crystal Fiber Interferometer, Ginu Rajan, Sunish Mathews, Gerald Farrell, Yuliya Semenova

Articles

An experimental investigation on liquid crystal coated tapered photonic crystal fiber (PCF) interferometer is presented in this paper. The interferometer is fabricated by tapering a small section of a PCF by collapsing the air holes and thinning down the air hole collapsed region to a micron size. Several interferometers are fabricated from different types of photonic crystal fibers and the temperature dependence studies are carried out to select an intrinsically temperature insensitive interferometer that can be used with liquid crystal (LC) materials. The properties of the LC materials to be used with the tapered PCF interferometers are also discussed. Temperature …

Bent Sms Fiber Structure For Temperature Measurement, Qiang Wu, Yuliya Semenova, Agus Hatta, Pengfei Wang, Gerald Farrell

Articles

We have proposed a temperature sensor fabricated using a bent SMS fiber structure. Our experimental results show, that by comparison to a sensor based on a straight SMS fiber structure, this temperature sensor has a much higher sensitivity of 31.97 pm/°C over a temperature range from 20 to 80 °C based on the measurement of the mean 3 dB wavelength shift and offers a resolution of 0.1 °C for temperature range from 45 to 80 °C when demodulated by a simple ratiometric interrogation technique.

Use Of A Bent Single Sms Fiber Structure For Simultaneous Measurement Of Displacement And Temperature Sensing, Qiang Wu, Agus Hatta, Pengfei Wang, Yuliya Semenova, Gerald Farrell

Articles

We have proposed the use of a single bent single-multiple-single mode (SMS) fiber structure to measure both displacement and temperature simultaneously and independently. Our experimental results show that this sensor has a sensitivity of 5.89 pm/μm for displacement and 11.6 pm/ºC for temperature.

A Voltage Sensor Based On A Singlemode-Multimode-Singlemode Fiber Structure, Agus Hatta, Yuliya Semenova, Ginu Rajan, Gerald Farrell

Articles

A voltage sensor based on a singlemode-multimodesinglemode (SMS) fiber structure, attached to a piezoelectric (PZT), utilized in a ratiometric optical power measurement scheme is proposed. The elongation of the PZT due to an applied voltage induces a strain on the SMS fiber structure and in turn results in a change in the transmission loss response of the SMS fiber structure. It is found that at selected wavelengths, a strong voltage dependence for the transmission loss of the SMS fiber structure can be achieved. The voltage information can be obtained from the power ratio of the system, assuming the system is …

Optimum Design For Maximun Wavelength Resolution For An Edge Filter Based Ratiometric System, Qiang Wu, Ginu Rajan, Pengfei Wang, Yuliya Semenova, Gerald Farrell

Articles

In this letter, we propose a high resolution temperature insensitive interrogation technique for FBG sensors where one FBG acts as an edge filter to interrogate a separate FBG sensor. A high resolution of better than 5 με in strain measurement range from 0 to 1100 με and the best resolution of better than 1 με were verified by experiments. An error of only ±2.2 με is achieved over a temperature range from 15 to 50 °C, indicating that this strain interrogation technique is temperature insensitive. Using an altered system configuration, the temperature was also measured simultaneously with a resolution better …