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Electrical and Computer Engineering

Technological University Dublin

2007

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Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels Nov 2007

Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels

Articles

This paper presents a method for precise measurement of atomic and molecular nitrogen in an oxygen-nitrogen dc plasma. This is achieved by monitoring the intensities of the atomic nitrogen spectral line at 821.6 nm and the molecular nitrogen bandhead at 337.1 nm, relative to the atomic oxygen spectral line at 844.7 nm. Oxygen is one of the most frequently used gases for surface chemical treatment, including deposition and etching, therefore the ability to measure and control the process and chemical composition of the process is essential. To validate this oxygen actimometry method for N2-xO2 (where x varies from 0 to …


Wireless Positioning Techniques: A Developer's Update, Seamus Rooney, Keith Gardiner, James Carswell Nov 2007

Wireless Positioning Techniques: A Developer's Update, Seamus Rooney, Keith Gardiner, James Carswell

Conference papers

This paper describes the current efforts to develop an open source, privacy sensitive, location determination software component for mobile devices. Currently in mobile computing, the ability of a mobile device to determine its own location is becoming increasingly desirable as the usefulness of such a feature enhances many commercial applications. There have been numerous attempts to achieve this from both the network positioning perspective and also from the wireless beacon angle not to mention the integration of GPS into mobile devices. There are two important aspects to consider when using such a system which are privacy and cost. This paper …


Experimental Measurement Of Overhead Associated With Active Probing Of Wireless Mesh Networks, Brian Keegan, Karol Kowalik Nov 2007

Experimental Measurement Of Overhead Associated With Active Probing Of Wireless Mesh Networks, Brian Keegan, Karol Kowalik

Conference papers

Wireless Mesh Networks (WMNs) represent the next generation wireless networks. The increased capacity of WMNs means that they are now capable of providing backhaul services traditionally maintained by wired networks. The attraction of WMNs is their ease of deployment and ability to self organise, self configure, and self heal. In order to successfully achieve this objective careful consideration must be applied when constructing a WMN. In order to optimise the operation of the network, data should traverse the network by means of the most efficient route. Characterisation and path selection will be determined by the routing algorithm coupled with the …


An Experimental Investigation Of Real-Time Video Transmission Over Ieee 802.11e Wlan Networks Using Txop, Nicola Cranley, Mark Davis Nov 2007

An Experimental Investigation Of Real-Time Video Transmission Over Ieee 802.11e Wlan Networks Using Txop, Nicola Cranley, Mark Davis

Conference papers

Real-time multimedia streaming applications require a strict bounded end-to-end delay and are considered to be bursty as each video frame is typically transmitted as a burst of packets. In this paper we show how the distribution of video frame sizes can be used to efficiently dimension the IEEE 802.11e TXOP limit parameter to efficiently deal with this burstiness in order to enhance the transmission of real-time video streaming services. Through experimental investigation, we show that by using the mean video frame size to dimension the TXOP limit parameter, the transmission delay for the video frame is reduced by 67% under …


The Effects Of Contention Among Stations On Video Streaming Applications Over Wireless Local Area Networks: An Experimental Approach, Nicola Cranley, Tanmoy Debnath Oct 2007

The Effects Of Contention Among Stations On Video Streaming Applications Over Wireless Local Area Networks: An Experimental Approach, Nicola Cranley, Tanmoy Debnath

Conference papers

Multimedia streaming applications have a large impact on the resource requirements of the WLAN. 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. For video streaming applications, packet loss and packets dropped due to excessive delay are the primary factors that affect the received video quality. In this paper, we experimentally analyse the effects of contention on the performance of video streaming applications with a given delay constraint …


The Capability Of The Edca Mechanism To Support Voice Traffic In A Mixed Voice/Data Transmission Over 802.11e Wlans: An Experimental Investigation, Miroslaw Narbutt, Mark Davis Oct 2007

The Capability Of The Edca Mechanism To Support Voice Traffic In A Mixed Voice/Data Transmission Over 802.11e Wlans: An Experimental Investigation, Miroslaw Narbutt, Mark Davis

Conference papers

In this paper we experimentally evaluate the capability of the EDCA mechanism to support voice traffic in a mixed voice/data transmission over 802.11e WLANs. In particular we investigate how real-time voice transmission can be supported by tuning four EDCA parameters, namely AIFSN, CWmin, CWmax and TXOP and how this impacts on background data transmission. The experimental set-up involves fifteen VoIP terminals sending bi-directional traffic between wired and wireless subnets and another station injecting various types of heavy background load to the wireless subnet. End-to-end voice transmission quality is predicted from time-varying transmission impairments with the use of the latest Appendix …


Wideband Printed Monopole Design Using A Genetic Algorithm, Matthias John, Max Ammann Sep 2007

Wideband Printed Monopole Design Using A Genetic Algorithm, Matthias John, Max Ammann

Articles

A method for the design and optimisation of wide-band printed planar monopoles using a genetic algorithm is presented. This novel technique employs overlapping sub-patches which ensures electrical contact in such constellations where two sub-patches are touching only at the corner, hence re-ducing losses. The method was usd optimisation of wide-band printed planar monopoles using a genetic algorithm is presented. This novel technique employs overlapping sub-patches which ensures electrical contact in such constellations where two sub-patches are touching only at the corner, hence re-ducing losses. The method was used to design a wideband monopole antenna with application in higher cellular, WLAN …


Video Frame Differentiation For Streamed Multimedia Over Heavilty Loaded Ieee 802.11e Wlan Using Txop, Nicola Cranley, Mark Davis Sep 2007

Video Frame Differentiation For Streamed Multimedia Over Heavilty Loaded Ieee 802.11e Wlan Using Txop, Nicola Cranley, Mark Davis

Conference papers

In this paper we perform an experimental investigation of using video frame differentiation in conjunction with the TXOP facility to enhance the transmission of parallel multimedia streaming sessions in IEEE 802.11e. The delay constraints associated with the audio and video streams that comprise a multimedia session pose the greatest challenge since real-time multimedia is particularly sensitive to delay as the packets require a strict bounded end-to-end delay. Video streaming applications are considered to be bursty. This burstiness is due to the frame rate of vide., the intrinsic hierarchical structure of the constituent video frame types. The TXOP facility is particularly …


Experimental Tuning Of The Aifsn Parameter To Prioritize Voice Over Data Transmission In 802.11e Wlan Networks, Miroslaw Narbutt, Mark Davis Aug 2007

Experimental Tuning Of The Aifsn Parameter To Prioritize Voice Over Data Transmission In 802.11e Wlan Networks, Miroslaw Narbutt, Mark Davis

Conference papers

In this paper we experimentally study the impact of one EDCA parameter, namely AIFSN on a mixed voice/data wireless transmission. In particular we investigate how the tuning of this parameter affects both the voice transmission quality and background data throughput. We predict end-to-end voice transmission quality from time varying transmission impairements using the latest Appendix to the ITU-T E-model. Our experiemental results show that the tuning of the AIFSN parameter can successfully prioritize voice transmission over data in a real 802.11e network. To the best of our knowledge this is the first experimental investigation on tuning of MAC layer parameters …


Experimental Tuning Of Aifsn And Cwmin Parameters To Prioritize Voice Over Data Transmission In 802.11e Wlan Networks, Miroslaw Narbutt, Mark Davis Aug 2007

Experimental Tuning Of Aifsn And Cwmin Parameters To Prioritize Voice Over Data Transmission In 802.11e Wlan Networks, Miroslaw Narbutt, Mark Davis

Conference papers

In this paper we experimentally study the impact of two EDCA parameters, namely AIFSN and CWmin, on a mixed voice/data wireless transmission. In particular we investigate how the tuning of these parameters affects both the voice transmission quality and background data throughput. We predict end-to-end voice transmission quality from time varying transmission impairments using the latest Appendix to the ITU-T E-model. Our experimental results show that the tuning of the EDCA parameters can be used to successfully prioritize voice transmission over data in real 802.11e networks. We also demonstrate that the AIFSN parameter more effectively protects voice calls against background …


An Experimental Investigation Of Parallel Multimedia Streams Over Ieee 802.11e Wlan Networks Using Txop, Nicola Cranley, Tanmoy Debnath, Mark Davis Jun 2007

An Experimental Investigation Of Parallel Multimedia Streams Over Ieee 802.11e Wlan Networks Using Txop, Nicola Cranley, Tanmoy Debnath, Mark Davis

Conference papers

In this paper we perform an experimental investigation of the IEEE 802.11 TXOP facility to enhance the transmission of parallel multimedia streaming sessions through efficient bandwidth reservation and explicitly consider both the audio and video streams. The delay constraints associated with the audio and video streams that comprise a multimedia session pose the greatest challenge since real-time multimedia is particularly sensitive to delay as the packets require a strict bounded end-to-end delay. We show how the TXOPlimit parameter can be efficiently dimensioned to reduce the tranmission delay for the video frames. Due to tis frame-based nature, video applications are considered …


Rare: Resource Aware Routing For Mesh, Karol Kowalik, Brian Keegan, Mark Davis Jun 2007

Rare: Resource Aware Routing For Mesh, Karol Kowalik, Brian Keegan, Mark Davis

Conference papers

An important element of any routing protocol used for Wireless Mesh Networks (WMNs) is the link cost function used to represent the radio link characteristic. The majority of the routing protocols for WMNs attempt to accurately characterise the radio link quality by constructing the link cost function from the measurements obtained using active probing techniques, which introduces overhead. In this paper we propose a new approach called Resource Aware Routing for mEsh (RARE) which instead employs passive monitoring to gather radio link information. This results in a smaller overhead than the other methods that require active network probing, and is …


Discontinuous Change In The Smectic Layer Thickness In Ferrielectric Liquid Crystals, V. P. Panov, J. K. Vij, Yuri Panarin, C. Blanc, V. Lorman, J. W. Goodby Jan 2007

Discontinuous Change In The Smectic Layer Thickness In Ferrielectric Liquid Crystals, V. P. Panov, J. K. Vij, Yuri Panarin, C. Blanc, V. Lorman, J. W. Goodby

Articles

The temperature dependence of the thickness of thick free-standing films is studied using a high-resolution film thickness measurement technique. A small discontinuity in the temperature dependence of the smectic layer thickness at every phase transition between ferro-, ferri-, and antiferroelectric phases is observed. We show that the major contribution to it arises from a change in the smectic tilt angle.


Macrobending Fiber Loss Filter, Ratiometric Wavelength Measurement And Application, Qian Wang, Ginu Rajan, Gerald Farrell, Pengfei Wang, Yuliya Semenova, Thomas Freir Jan 2007

Macrobending Fiber Loss Filter, Ratiometric Wavelength Measurement And Application, Qian Wang, Ginu Rajan, Gerald Farrell, Pengfei Wang, Yuliya Semenova, Thomas Freir

Articles

A macrobending standard single-mode fibre (SMF28) is optimized as an edge filter, with the optimal bending radius and length determined according to the bend loss and polarization sensitivity of the bending fibre. An all-fibre ratiometric wavelength system is built and calibrated. The system's accuracy and resolution is discussed with the influence of noise of input signal and photodetectors. Finally, the ratiometric system is employed for the demodulation of FBG strain sensing.


The Role Of Spontaneous Polarization And The Thickness Of Alignment Layers On The V-Shaped Switching In Flc Cells, V. Manjuladevi, J.K. Vij, Yuri Panarin Jan 2007

The Role Of Spontaneous Polarization And The Thickness Of Alignment Layers On The V-Shaped Switching In Flc Cells, V. Manjuladevi, J.K. Vij, Yuri Panarin

Articles

Ferroelectric liquid crystal mixtures with the various values of spontaneous polarizations were prepared, and the substrates were coated with different thicknesses of aligning agent. The frequency dependence of the electrooptic response of these materials in cells with various thickness of alignment layers has been measured. The coercive voltage as well as the contrast ratios are calculated. Our results support the ‘‘electrostatic model’’, according to which both the value of spontaneous polarization and the thickness of the alignment layer play important roles in the V-shaped switching.


A Novel Wideband Semi-Planar Miniaturized Antenna, Giuseppe Ruvio, Max Ammann Jan 2007

A Novel Wideband Semi-Planar Miniaturized Antenna, Giuseppe Ruvio, Max Ammann

Articles

A semi-planar miniaturized antenna which operates over the FCC allocated UWB spectrum is presented. The small antenna comprises a folded conducting element connected to a printed section. Several solutions are introduced which create different current paths increasing the effective dimensions of the antenna. The antenna is examined for the stand-alone case and for the antenna mounted in various locations on a larger handset-type groundplane. The impedance and radiation characteristics show a relative independence of the groundplane size and the antenna location on it. The proposed antenna is a valuable candidate for handset applications due to its compactness. The proposed antenna …


Making Olsr Aware Of Resources, Karol Kowalik, Brian Keegan, Mark Davis Jan 2007

Making Olsr Aware Of Resources, Karol Kowalik, Brian Keegan, Mark Davis

Conference papers

An important element of any routing protocol used for Wireless Mesh Networks (WMNs) is the link cost function used to represent the radio link characteristic. The majority of the routing protocols for WMNs attempt to accurately characterise the radio link quality by constructing the link cost function from the measurements obtained using active probing techniques which introduces overhead. In this paper we present a modified version of the Optimized Link State Routing (OLSR) protocol which uses the link cost function values provided the Resource Aware Routing for mEsh (RARE) module which employs passive monitoring to gather radio link information. This …


Investigation On Proximity-Coupled Microstrip Integrated Pv Antenna, Maria Roo Ons, S. Shynu, Max Ammann, Sarah Mccormack, Brian Norton Jan 2007

Investigation On Proximity-Coupled Microstrip Integrated Pv Antenna, Maria Roo Ons, S. Shynu, Max Ammann, Sarah Mccormack, Brian Norton

Conference papers

The use of polycrystalline silicon solar cells (156 times156 mm) as a groundplane for a proximity-coupled microstrip square patch antenna (30 times 30 mm) is investigated. Four different models that arise from the different possible positions of the cell with respect to patch, were simulated, fabricated and compared to an ideal PEC ground plane antenna of the same size. It was found that the use of the solar cell as ground plane is feasible, yielding similar impedance bandwidth (around 4%, 3.5% for the PEC) with reasonable gain. The feasibility of using poly-crystalline solar cells as a ground plane, instead of …


Investigation On Miniature Wideband Patch Antenna For Portable Wireless And Cellular Applications, Xiulong Bao, Max Ammann Jan 2007

Investigation On Miniature Wideband Patch Antenna For Portable Wireless And Cellular Applications, Xiulong Bao, Max Ammann

Conference papers

A low-profile miniature antenna with very wide bandwidth is proposed for emerging multimode devices. It comprises a small circular patch antenna loaded by a metallic annular-ring and located on a laminate with a slotted ground plane. The design achieves a very compact low-profile antenna with broadband performance. By optimizing the parameters of the annular-ring patch antenna, very broadband characteristics can be obtained. The measured results show that the antenna achieves a 10 dB return loss from 1.383 GHz to 2.210 GHz, (827 MHz) ie about 47% with respect to the centre frequency 1.796 GHz. The measured results are in good …


Low-Profile Rolled Planar Antenna With Wide Bandwidth, Giuseppe Ruvio, Max Ammann Jan 2007

Low-Profile Rolled Planar Antenna With Wide Bandwidth, Giuseppe Ruvio, Max Ammann

Conference papers

A novel size-reduction technique for a planar monopole type antenna is presented. By rolling the planar element of this antenna, a low-profile radiator with broad impedance bandwidth is obtained without excessively perturbing its radiation properties. The proposed antenna is capable of covering frequencies in the range 3.1 GHz to 15 GHz. The antenna yields a high gain with high radiation efficiency across the full bandwidth. Radiation patterns show good omnidirectional features, so it is a remarkable candidate for in-door or vehicular applications where large frequency range is required


Modelling And Computer Simulation Of Radarscreening Using Plasma Clouds, Jonathan Blackledge Jan 2007

Modelling And Computer Simulation Of Radarscreening Using Plasma Clouds, Jonathan Blackledge

Conference papers

Following a brief introduction on the principles of screening an aerospace vehicle using a plasma, we develop models for the Impulse Response Functions (IRFs) associated with microwave (Radar) back-scattering from a strong and weakly ionized plasma screen. For a weakly ionized plasma, the conductivity is determined by the number density of electrons. We develop a model for an electron beam induced plasma that includes the effect of cascade ionization and losses due to diffusion and recombination. Qualitative results are then derived for the number density of a plasma screen over a sub-sonic aerospace vehicle and a numerical simulation considered that …


Comparative Evaluation Of Two Models Of Upqc For Suitable Interface To Enhance Power Quality, Malabika Basu, S. P. Das, Gopal Dubey Jan 2007

Comparative Evaluation Of Two Models Of Upqc For Suitable Interface To Enhance Power Quality, Malabika Basu, S. P. Das, Gopal Dubey

Articles

Majority of the dispersed generations from renewable energy sources are connected to the grid through power electronic interface, which introduce additional harmonics in the distribution systems. Research is being carried out to integrate active filtering with specific interface such that a common power quality (PQ) platform could be achieved. For generalized solution, a unified power quality conditioner (UPQC) could be the most comprehensive PQ protecting device for sensitive non-linear loads, which require quality input supply. Also, load current harmonic isolation needs to be ensured for maintaining the quality of the supply current. The present paper describes two control scheme models …


Optical Performance Of Non-Blocking 4x4 Optical Switch: Simulation And Experiment, V. Alex, A. Dubtsov, Yuri Panarin, T. Wilkinson Jan 2007

Optical Performance Of Non-Blocking 4x4 Optical Switch: Simulation And Experiment, V. Alex, A. Dubtsov, Yuri Panarin, T. Wilkinson

Articles

A prototype of pure non-blocking 4x4 optical LC switch was designed and built. This switch is based on conventional LCD technology, where the each pixel controlled the polarization state of the light beam. An addressing algorithm was described. The optical performance of the switch, such as cross-talk and insertion loss, was simulated and experimentally studied. The suggested approach offers several advantages over the conventional cross-point architecture such as: cost; complexity; size; adjustment; and optical performance.


Spline Based Geometry For Printed Monopole Antennas, Matthias John, Max Ammann Jan 2007

Spline Based Geometry For Printed Monopole Antennas, Matthias John, Max Ammann

Articles

A novel Bezier spline-based geometry for printed monopole antennas is presented. Quadratic curves are used to describe the outline of the radiating element. The geometry is optimised by a genetic algorithm. A small number of control points are used to define the geometry, ensuring a small search space for the GA. The resulting antenna has an impedance bandwidth from 1.44 to 14.7 GHz


Wideband Reconfigurable Rolled Planar Monopole Antenna, Giuseppe Ruvio, Max Ammann, Zhi Ning Chen Jan 2007

Wideband Reconfigurable Rolled Planar Monopole Antenna, Giuseppe Ruvio, Max Ammann, Zhi Ning Chen

Articles

A novel technique to reconfigure the frequency range of a planar monopole antenna is presented. By adjusting the degree of spiral tightness, a shift of the well-matched operating frequency range is achieved. The proposed antenna is capable of covering the frequencies in the range from 2.9 to 15 GHz, depending on the degree of spiral tightness. The antenna yields a high-efficiency across the full operating bandwidth. Radiation patterns show good omni-directional features in all primary cuts and remain relatively stable with the change of antenna configuration, so that it is a remarkable candidate for indoor or mobile applications where a …


Quantum Dot Energy Relaxation Mediated By Plasmon Emission In Doped Covalent Semiconductor Heterostructures, A. V. Fedorov, Anna Baranov, I. D. Rukhlenko, T. S. Perova, Kevin Berwick Jan 2007

Quantum Dot Energy Relaxation Mediated By Plasmon Emission In Doped Covalent Semiconductor Heterostructures, A. V. Fedorov, Anna Baranov, I. D. Rukhlenko, T. S. Perova, Kevin Berwick

Articles

The interaction between interface plasmons within a doped substrate and quantum dot electrons or holes has been theoretically studied in double heterostructures based on covalent semiconductors. The interface plasmon modes, the corresponding dispersion relationship, and the intraband carrier relaxation rate in quantum dots are reported. We find the critical points in the interface plasmon density of states for multilayered structures results in enhanced quantum dot intraband carrier relaxation when compared to that for a single heterostructure. A detailed discussion is made of the relaxation rate and the spectral position dependencies on the quantum dot layer thickness as well as on …


Design Of Compact Multi-Band Ebg Structures, Xiulong Bao, Max Ammann Jan 2007

Design Of Compact Multi-Band Ebg Structures, Xiulong Bao, Max Ammann

Conference papers

Several novel compact multiple-band high-impedance surface EBG structures are presented. By utilizing four S-shape corrugated arms or spiral arms connected to the edge of a small square patch to increase the inductance, the resonant frequency of the EBG structure can be significantly reduced. In order to broaden the width of the stopband and adjust the ratio of the centre frequencies for multi-band EBG a log periodic distance between the S-shape strips is implemented. The effects of the parameters of the EBG structure on the width of stopbands are discussed in detail. The results show that the proposed novel EBG structure …


Dual Frequency Dual Circularly-Polarised Patch Antenna With Wide Beamwidth, Xiulong Bao, Max Ammann Jan 2007

Dual Frequency Dual Circularly-Polarised Patch Antenna With Wide Beamwidth, Xiulong Bao, Max Ammann

Conference papers

A novel probe-fed single-layer annular-ring patch antenna for dual-frequency circular polarization is evaluated numerically and experimentally verified. The proposed antenna consists of a small circular patch surrounded by two concentric annular-rings, which is loaded by an unequal lateral cross-slot ground plane. The circularly-polarized frequency ratio of the two resonant modes is tunable to a small value, suitable for wireless communications systems. The patch size of the proposed antenna is reduced by about 53% compared to the conventional circular patch at a given frequency. The radiation characteristics of the novel antenna are also presented.


Inset-Fed Mircrostrip Patch Antenna With Integrated Polycrystalline Photovoltaic Solar Cell, S. Shynu, Maria Roo Ons, Max Ammann, Sarah Gallagher, Brian Norton Jan 2007

Inset-Fed Mircrostrip Patch Antenna With Integrated Polycrystalline Photovoltaic Solar Cell, S. Shynu, Maria Roo Ons, Max Ammann, Sarah Gallagher, Brian Norton

Conference papers

A novel method of integrating microstrip patch antennas and polycrystalline silicon solar cells for application in autonomous communication systems is presented. The DC and RF functions are intimately linked, by using the silver DC bus bars of the solar cell as the ground plane of the microstrip patch. The performance of the solar antenna is compared with standard microstrip patch. Detailed studies of the effect of the solar cell on the microstrip antenna are then carried out. The effects of solar cell integration, DC loading and variation in incident photon intensity of the silicon layer on the performance of the …


Printed Band-Rejection Uwb Antenna With H-Shaped Slot, Xiulong Bao, Max Ammann Jan 2007

Printed Band-Rejection Uwb Antenna With H-Shaped Slot, Xiulong Bao, Max Ammann

Conference papers

The development of the high data rate wireless communication systems, has placed significant demands on antenna designers, in particular, the requirement for smaller elements with broader bandwidths. In this paper, a novel UWB antenna with notch-band frequency is studied. Effects of the various parameters for antenna performances are also discussed. An optimized compact UWB antenna with notch-frequency function is fabricated and experimentally examined. The measured results show the proposed UWB antenna can achieve a return loss greater than 10 db over an ultrawide bandwidth, of 9.8 GHz, from 2.97 GHz to 12.77 GHz with a tunable notch-frequency band of 5.15 …