Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2007

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 17611 - 17640 of 18552

Full-Text Articles in Entire DC Network

Engineering Science As Opposed To Natural Science, Eugene Coyle, Mike Murphy, William Grimson Jan 2007

Engineering Science As Opposed To Natural Science, Eugene Coyle, Mike Murphy, William Grimson

Presentations

No abstract provided.

Go to article

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 …

Go to article

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.

Go to article

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 …

Go to article

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 …

Go to article

Enhancement Of Maximum Time Delay In One Fiber Segment Slow Light Systems Based On Stimulated Brillouin Scattering, Ronny Henker, Thomas Schneider, Markus Junker, Kai-Uwe Lauterbach, Max Ammann, Andreas Schwarzbacher Jan 2007

Enhancement Of Maximum Time Delay In One Fiber Segment Slow Light Systems Based On Stimulated Brillouin Scattering, Ronny Henker, Thomas Schneider, Markus Junker, Kai-Uwe Lauterbach, Max Ammann, Andreas Schwarzbacher

Conference papers

An effective method to enhance the time delay in SBS-based slow-light systems by decoupling the delay from the Brillouin gain is shown. A drastic improvement of the time delay in one fiber segment was achieved.

Go to article

Investigation Of Fast Light In Long Optical Fibers Based On Stimulated Brillouin Scattering, Kai-Uwe Lauterback, Thomas Schneider, Ronny Henker, Marcus Junker, Max Ammann, Andreas Schwarzbacher Jan 2007

Investigation Of Fast Light In Long Optical Fibers Based On Stimulated Brillouin Scattering, Kai-Uwe Lauterback, Thomas Schneider, Ronny Henker, Marcus Junker, Max Ammann, Andreas Schwarzbacher

Conference papers

A simple method to generate a negative time delay in SBS-based fast-light systems using Brillouin gain and loss is shown. We achieved a maximum negative time delay of 32.4 ns in one long fiber segment.

Go to article

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 …

Go to article

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 …

Go to article

Thermal Control Of An Occupied Room: Investigating The Use Of Carbon Dioxide Concentration As An Auxiliary Control Variable, Kevin O'Connell, Aidan O'Dwyer Jan 2007

Thermal Control Of An Occupied Room: Investigating The Use Of Carbon Dioxide Concentration As An Auxiliary Control Variable, Kevin O'Connell, Aidan O'Dwyer

Conference papers

This paper details the theoretical and experimental work done in the examination of the relationship between human generated carbon dioxide concentration and temperature rise in an occupied room. Generation of carbon dioxide by humans is linked to metabolic rate and heat generation. Therefore, carbon dioxide concentration may be used as an indicator of occupancy in a room. Typically, a heating control system will react slowly to changes in room occupancy if temperature is used as the process variable. The aim of the work was to establish if carbon dioxide concentration in the space could be used as an auxiliary control …

Go to article

Development Of The Analytical Design Method For Single Stage Phase Lead And Phase Lag Compensators, Aidan O'Dwyer Jan 2007

Development Of The Analytical Design Method For Single Stage Phase Lead And Phase Lag Compensators, Aidan O'Dwyer

Conference papers

The design of phase lead and phase lag compensators in the frequency domain, using the Bode diagram, is a commonly used method of designing control systems and is taught in many undergraduate and postgraduate courses in control engineering. The graphical trial and error procedure used may be replaced by an analytical procedure. However, the analytical approach tends to be formulated as a “black-box” approach in textbooks, without engineering insight. This paper presents the full development of the analytical design procedure. The instructional approach has been successfully used by the author over the past two academic years.

Go to article

Transfer Function Modelling: A Student-Centred Learning Approach, Aidan O'Dwyer Jan 2007

Transfer Function Modelling: A Student-Centred Learning Approach, Aidan O'Dwyer

Conference papers

Traditionally, the modelling of real systems in engineering, using transfer functions, has been done in a mathematically intense manner. However, non-traditional learners such as mature students, part-time students and students without a conventional second-level educational background may not have strong mathematical foundations; in addition, all students increasingly expect technical work which is practical and which motivates independent learning. This paper reports on, reflects on and evaluates an innovative experiment developed by the author to estimate a transfer function model of a person’s eye-brain-hand motor response. In the experiment, carried out using a PC with data acquisition capability, the person is …

Go to article

Experiences With Virtual Learning Environments In Control Engineering Education, Aidan O'Dwyer Jan 2007

Experiences With Virtual Learning Environments In Control Engineering Education, Aidan O'Dwyer

Conference papers

The twin pressures of the need for students to learn a wider variety of concepts, ideally in a self-learning mode, and the reduction in class contact time has led to the use of increased levels of information technology in control engineering education. This paper reports on, reflects on, and evaluates the author’s use of virtual laboratories (computer based laboratories available on the internet) in control engineering modules at DIT Kevin St. The use of the virtual laboratories helps in the ongoing evolution of the teaching approach from a traditional didactic lecture and laboratory course to a more learner-centred approach. The …

Go to article

Stability Analysis And Control Synthesis Of Affine Fuzzy Systems, Ruiyao Gao, Aidan O'Dwyer Jan 2007

Stability Analysis And Control Synthesis Of Affine Fuzzy Systems, Ruiyao Gao, Aidan O'Dwyer

Conference papers

This paper presents an approach to stability analysis and control synthesis of affine fuzzy systems. The analysis is based on quadratic Lyapunov functions. The approach considers the nonlinear offset terms in affine fuzzy systems as non-vanishing perturbations added to the corresponding nominal linear blending systems. The affine fuzzy system is bounded by an ultimate limit if the corresponding linear blending system is exponentially stable. A state feedback controller with an extra term is designed with guaranteed global stability. The ultimate bounds are determined for both the open loop system and the compensated system.

Go to article

Using Controller Tuning Formulae To Improve Performance, Aidan O'Dwyer Jan 2007

Using Controller Tuning Formulae To Improve Performance, Aidan O'Dwyer

Conference papers

The proportional integral derivative (PID) controller is the most dominant form of automatic controller in industrial use today. With this device, it is necessary to adjust the controller parameters according to the nature of the process. Thus, for effective control of a HVDC system, for example, specific values need to be chosen for the P, I and D parameters, which will be different for the values required to control, for example, an induction motor drive. This tailoring of controller to process is known as controller tuning. Controller tuning is easily and effectively performed using tuning rules (i.e. formulae for controller …

Go to article

Biotechnology, Life Sciences And Control Engineering:Some Synthesis Issues, Aidan O'Dwyer Jan 2007

Biotechnology, Life Sciences And Control Engineering:Some Synthesis Issues, Aidan O'Dwyer

Conference papers

The synthesis of biotechnology, life sciences and control engineering is receiving increasing interest. The purpose of this contribution (and the associated poster) is to raise awareness of some of this synthesis work.

Go to article

Sensors For The Detection Of Hazardous Emissions, Aidan O'Dwyer Jan 2007

Sensors For The Detection Of Hazardous Emissions, Aidan O'Dwyer

Conference papers

This contribution will detail recent developments in sensor technology for the detection of hazardous emissions. The accurate measurement of such emissions is necessary if they are to be controlled to the appropriate regulations.

Go to article

Academic Change In Higher Education In Europe, Kevin Kelly, Mike Murphy Jan 2007

Academic Change In Higher Education In Europe, Kevin Kelly, Mike Murphy

Conference papers

This paper analyses academic change in higher education internationally but mainly in Europe. It examines one College in Ireland as it faces major change and examines whether best practice change that has been successful elsewhere might be appropriate in this particular setting, with it’s own culture and history. Research is ongoing, using qualitative inquiry and fourth generation evaluation which seeks to address the concerns and issues of stakeholders. It is an illuminative evaluation project that seeks to allow senior management in the College see what is happening elsewhere and evaluate whether such methods might be appropriate in their own college. …

Go to article

Changing Universities, Kevin Kelly Jan 2007

Changing Universities, Kevin Kelly

Conference papers

No abstract provided.

Go to article

An Approach To Unification Using A Linear Systems Model For The Propagation Of Broad-Band Signals, Jonathan Blackledge Jan 2007

An Approach To Unification Using A Linear Systems Model For The Propagation Of Broad-Band Signals, Jonathan Blackledge

Articles

We review the inhomogeneous scalar Helmholtz equation in three-dimensions and the scattering of scalar wavefields from a scatterer of compact support. An asymptotic solution is then considered representing the effect of the frequency approaching zero when a ‘wavefield’ reduces to a ‘field’. The characteristics of ultra-low frequency Helmholtz scattering are then considered and the physical significance discussed of a model that is based on the scattering of Helmholtz wavefields over a broad frequency spectrum. This is equivalent to using a linear systems approach for modelling the propagation, interaction and detection of broad-band signals and provides an approach to the classification …

Go to article

Diffusion And Fractional Diffusion Based Models For Multiple Light Scattering And Image Analysis, Jonathan Blackledge Jan 2007

Diffusion And Fractional Diffusion Based Models For Multiple Light Scattering And Image Analysis, Jonathan Blackledge

Articles

This paper considers a fractional light diffusion model as an approach to characterizing the case when intermediate scattering processes are present, i.e. the scattering regime is neither strong nor weak. In order to introduce the basis for this approach, we revisit the elements of formal scattering theory and the classical diffusion problem in terms of solutions to the inhomogeneous wave and diffusion equations respectively. We then address the significance of these equations in terms of a random walk model for multiple scattering. This leads to the proposition of a fractional diffusion equation for modelling intermediate strength scattering that is based …

Go to article

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.

Go to article

Engineering Science As Opposed To Natural And Applied Science, Eugene Coyle, Mike Murphy, William Grimson Jan 2007

Engineering Science As Opposed To Natural And Applied Science, Eugene Coyle, Mike Murphy, William Grimson

Books/Book chapters

In exploring the epistemology of engineering science we propose a model of engineering. This model incorporates the goals of engineering, the approach to engineering (also called the engineering method) and the role of experience in engi-neering. The basis for understanding the nature of engineering science will be ex-plored, and will be contrasted with natural science. To begin, a large-scale engi-neering project that was successfully completed in Ireland many years ago is dis-cussed - specifically, the development of a megalithic passage tomb as an exemplar of the engineering method in structural design, project management and aesthetics. This exemplar firmly demonstrates that …

Go to article

Engineering - An Inherently Philosophical Enterprise, William Grimson Jan 2007

Engineering - An Inherently Philosophical Enterprise, William Grimson

Books/Book chapters

No abstract provided.

Go to article

From Certificates To Doctorates, By Degrees: Dublin Institute Of Technology - A Photographic Memoir, Jimmie Robinson Jan 2007

From Certificates To Doctorates, By Degrees: Dublin Institute Of Technology - A Photographic Memoir, Jimmie Robinson

Books

Jimmie Robinson has photographed visitors and events at Dublin Institute of Technology for 43 years. In this photographic memoir, he chronicles the development of DIT over its first 120 years from behind the lens.

Go to article

Microstructures And Viscoelastic Properties Of Anisotropic Magnetorheological Elastomers, Lin Chen Jan 2007

Microstructures And Viscoelastic Properties Of Anisotropic Magnetorheological Elastomers, Lin Chen

Articles

The microstructures and viscoelastic properties of anisotropic magnetorheological elastomers were investigated in this paper. The measurement results show that their mechanical properties are greatly dependent on the magnetic flux density applied in preparation. A finite-column model was proposed to describe the relations between the microstructures and the viscoelastic properties. The simulation results agree well with the experimental results.

Go to article

Investigation On Magnetorheological Elastomers Based On Natural Rubber, Lin Chen Jan 2007

Investigation On Magnetorheological Elastomers Based On Natural Rubber, Lin Chen

Articles

Magnetorheological Elastomers (MR Elastomers or MREs) are a kind of novel smart material, whose mechanical, electrical, magnetic properties are controllable under applied magnetic fields. They have attracted increasing attentions and broad application prospects. But conventional MREs are limited to wide applications because their MR effects and mechanical performances are not high enough. This paper aims to optimize the fabrication method and to fabricate good natural rubber based MREs with high modulus by investigating the influences of a variety of fabrication conditions on the MREs performances, such as matrix type, external magnetic flux density, and temperature, plasticizer and iron particles. Among …

Go to article

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 …

Go to article

Hologram-Based Humidity Indicator For Domestic And Packaging Applications, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin Jan 2007

Hologram-Based Humidity Indicator For Domestic And Packaging Applications, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin

Conference Papers

A passive indicator for Relative Humidity based on a photopolymer recorded hologram has been developed. The indicator works on the principle that the wavelength reconstructed by a reflection hologram is dependent on the spacing between the fringe planes of the hologram. As the Relative Humidity changes, the hologram swells or shrinks and the apparent colour of the reconstructed image changes. The response time, operational range and reversibility of the indicator have been studied in a controlled humidity environment. Response times from less than a minute to tens of minutes depending on the holograms physical properties have been measured. Indicators with …

Go to article

Risk Reduction Through Technological Control Of Personal Information, Shirley Atkinson Jan 2007

Risk Reduction Through Technological Control Of Personal Information, Shirley Atkinson

School of Engineering, Computing and Mathematics Theses

Abuse and harm to individuals, through harassment and bullying, coexist with Identity Theft as criminal behaviours supported by the ready availability of personal information. Incorporating privacy protection measures into software design requires a thorough understanding about how an individual's privacy is affected by Internet technologies. This research set out to incorporate such an understanding by examining privacy risks for two groups of individuals, for whom privacy was an important issue, domestic abuse survivors and teenagers. The purpose was to examine the reality of the privacy risks for these two groups. This research combined a number of approaches underpinned by a …

Go to article

First Prev Next Last