Electrical and Computer Engineering Commons^™

Reversible Photoluminescence Quenchin Of Cdse/Zns Quantum Dots Embedded In Porous Glass By Ammonia Vapor, A. O. Orlova, Yu A. Gromova, V. G. Maslov, O. V. Andreeva, A. V. Baranov, A. V. Federov, A. V. Prudnikau, M. V. Artemyev, Kevin Berwick

Articles

The photoluminescence response of semiconductor CdSe/ZnS quantum dots embedded in a borosilicate porous glass matrix to exposure to ammonia vapor is investigated. Formation of surface complexes on the quantum dots results in quenching of the photoluminescence and a shortening of the luminescence decay time. The process is reversible, desorption of ammonia molecules from the quantum dot surface causes the photoluminescence to recover. The sensitivity of the quantum dot luminescence intensity and decay time to the interaction time and the reversibility of the photoluminescence changes makes the CdSe/ZnS quantum dot in porous glass system a candidate for use as an optical …

The Influence Of Light Beam Convergence On The Stop-Bands Of A One-Dimensional Photonic Crystal, Vladimir A. Tolmachev, Kevin Berwick, Tatiana S. Perova

Articles

The influence of beam convergence on the photonic band-gaps, or stop-bands (SBs), of onedimensional photonic crystals (1D PCs) is investigated. The investigation is based on an analysis of the gap map obtained from reflection spectra, calculated by the transfer matrix method for various angles of light incidence, φ, The calculated data is compared with reflection spectra taken using Fourier Transform Infrared microspectroscopy. It was found that the introduction of the parameter, Δφ to account for the focused light beam, for angles up to 20°, has little effect on the first, or lowest SB and the SBs adjacent to it. However, …

Financial Forecasting Using The Kolmogorov-Feller Equation, Jonathan Blackledge, Marc Lamphiere, Kieran Murphy, Shaun Overton

Articles

An approach to analysing a financial time series using the Kolmogorov-Feller Equation is considered, in particular, the Generalised Kolmogorov-Feller Equation (GKFE) subject to variations in the Stochastic Volatility. Using the Mittag-Leffler memory function, we derive an expression for the Impulse Response Function associated with a short time window of data which is then used to derive an algorithm for computing a new index using a standard moving window process. It is shown that application of this index to financial time series, subject to a low volatility condition, correlates with the start, direction and end of a trend depending on the …

Selection Of Design Parameters To Reduce The Zero-Sequence Circulating Current Flow In Parallel Operation Of Dc Linked Multiple Shunt Apf Units, Shafiuzzaman Khadem, Malabika Basu, Michael Conlon

Articles

Capacity enhancement and operational flexibility are two of the important limitations of the centralized shunt APF unit. These limitations can be conquered by the operation of multiple APF units in parallel and connected back to back by a common DC link capacitor. In that case, a circulating current (CC) flows within the APF units. This CC flow becomes out of control when the APF units operate in hysteresis based current controlled mode. One of the difficulties of this CC flow control or reduction is the variable switching frequency of the APF units. In this paper the model for CC flow …

Estimation Of Wave Energy From Wind Velocity, Jonathan Blackledge, Eugene Coyle, Derek Kearney, Ronan Mcguirk, Brian Norton

Articles

The aim of this paper is to report on a possible correlation between the Levy index for wind velocity and the mean Energy Density of sea surface waves in the same location. The result is based on data obtained from 6 buoys located around the coast of Ireland and maintained by the Marine Institute of Ireland and a further 144 buoys located at various locations off the coast of the United States of America and maintained by the National Data Buoy Centre. These buoys provide historical data on the wind velocity, wave height and wave period as well as other …

Correspondence: Comparing Led Luminaires, James Duff

Articles

A recent editorial within Lighting Research and Technology 1 suggests the need for ‘a simple set of questions to ask the LED supplier’. This article will present such a set of questions, but also, and perhaps more importantly, a set of responses that might be considered appropriate. The information used to form these questions and answers has been drawn from a number of useful resources 2-7, interaction with various lighting professionals and through the authors own experience. The purpose of these questions is to generate discussion. The author understands the questions posed can be improved upon and it is hoped …

Proximity Heating Effects In Power Cables, Jonathan Blackledge, Eugene Coyle, Kevin O'Connell

Articles

Researchers at Technological University Dublin (DIT) have developed a new modelling system for evaluating the two and three dimensional heating effects in power cables due to harmonic distortion and proximity field effects.

Lumped Time-Delay Compensation Scheme For Coding Synchronization In The Nonlinear Spectral Quantization-Based All-Optical Analog-To-Digital Conversion, Zhe Khang, Jinhui Yuan, Qiang Wu, Tao Wang, Sha Li, Chongxiu Y, Gerald Farrell

Articles

this paper, we propose a novel lumped time-delay compensation scheme for the all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. By inserting a segment of negative dispersion fiber between the quantization and the coding module, the time delay of different quantized pulses can be accurately compensated with a simple structure compared to the multiple time-delay lines. The simulation results show that the coding pulses can be well synchronized using a span of fiber, with the flattened negative dispersion within the wavelength range of 1558-1620 nm. In addition, the problems of pulse broadening and time error are …

Biaxial Order Parameter In The Homologous Series Of Orthogonal Bent-Core Smectic Liquid Crystals, S. Sreenilayam, Yuri Panarin, J. K. Vij, M. Osipov, A. Lehmann, C. Tschierske

Articles

The fundamental parameter of the uniaxial liquid crystalline state that governs nearly all of its physical properties is the primary orientational order parameter (S) for the long axes of molecules with respect to the director. The biaxial liquid crystals (LCs) possess biaxial order parameters depending on the phase symmetry of the system. In this paper we show that in the first approximation a biaxial orthogonal smectic phase can be described by two primary order parameters: S for the long axes and C for the ordering of the short axes of molecules. The temperature dependencies of S and C are obtained …

Three Dimensional Simulation Of The Radiation Field Patterns Generated By An Integrated Antenna, Jonathan Blackledge, Bazar Babajanov

Articles

Simulating the electromagnetic field patterns generated by integrated antennas uses in mobile phones, for example, is fundamental to understanding their transmission characteristics and thereby engineering designs that optimize the directional properties of electromagnetic propagation. Modern integrated antennas have complex three-dimensional geometry designed to optimize their performance in terms of their multi-band and multi -modal attributes. This geometry, coupled with their close proximity to other component of the device (such as the battery and Printed Circuit Board, for example) produce complex field patterns due to the scattering of the electric (and magnetic) field within a spatial domain that is the same …

Evaluation Of Proximity Heating Effects In Power Cables, Jonathan Blackledge, Eugene Coyle, Kevin O'Connell

Articles

No abstract provided.

Inverter Performance For Small Wind Turbines When Connected In Paralled With The Low-Voltage Distribution System, Jonathan Blackledge, Eugene Coyle, Derek Kearney, Eamonn Murphy

Articles

Small wind turbines have been installed in urban and turbulent locations with surprisingly poor performance and this has been backed up by data from a trial at the Technological University Dublin. In order to develop the small wind turbine industry a careful examination of assessment methods for the wind resource is required. Small wind turbines connected in parallel with the grid use inverters. As the wind turbine is not always at max output, a Weighted Average Efficiency for wind inverters is proposed. Pitfalls associated with developing an accurate weighted average efficiency for an inverter are identified and this will enable …

The Fractional Schrodinger-Klein-Gordon Equation And Intermediate Relativism, Jonathan Blackledge, Bazar Babajanov

Articles

By considering a random walk model compounded in Einstein's evolution equation, we show that both the classical Schrodinger and Klein-Gordon equations can be viewed a s consequence of introducing a memory function.

The purpose of this is to derive a wave equaiton that, on a phenomenological basis at least, describes the transitional characteristics of wave functions for spin-less particles that may exist in the intermediate of "semi relativistic regime.

On The Dirac Scattering Problem, Jonathan Blackledge, Bazar Babajanov

Articles

We consider a method of solving the Dirac scattering problem based on an approach previously used by the authors to solve the Schrodinger scattering problem to develop a conditional exact scattering solution and an unconditional series solution. We transform the Dirac scattering problem into a form that facilitates a soltuion based on the relativistic Lippmann-Schwinger equation using the relativistic Green's function that is transcendental in terms of the scattered field. Using the Dirac operator, this solution is transformed further to yield a modified relativistic Lippman-Schwinger equation that is also transcendental in terms of the scattered field. This modified solution faclitates …

A Review Of Existing Microgrid Architectures, Lubna Mariam, Malabika Basu, Michael Conlon

Articles

The future electricity network must be flexible, accessible, reliable, and economic according to the worldwide smartgrid initiative. This is also echoed by the Sustainable Energy Authority of Ireland (SEAI) and European Electricity Grid Initiative (EEGI). In order to facilitate these objectives and to reduce green house gas (GHG) emission, research on various configurations of microgrid system is gaining importance, particularly with high penetration of renewable energy sources. Depending on the resource availability, geographical locations, load demand, and existing electrical transmission and distribution system, uG can be either connected to 6the grid or can work in an autonomous mode. Storage can …

Dual-Band Omnidirectional Circularly Polarized Antenna, Adam Narbudowicz, Xiulong Bao, Max Ammann

Articles

A dual-band omnidirectional circularly polarized antenna is proposed. The antenna comprises back-to-back microstrip patches fed by a coplanar waveguide. A very low frequency ratio of 1.182 has been achieved, which can be easily tuned by adjusting four lumped capacitors incorporated into the antenna. An analysis of the omnidirectional circular polarization mechanism as well the dual band operation is provided and confirmed by numerical and experimental data. Key parameters to tune the resonant frequencies and the axial ratio have been identified. The prototype antenna provides omnidirectional circular polarization in one plane with cross polar isolation better than 12 dB for both …

Proximity Study Of A Uwb Directional Conformal Antenna On Water Pipe, Domenico Gaetano, Max Ammann, Patrick Mcevoy, Matthias John, Louise Keating, Frances Horgan

Articles

A preliminary study on the conformal properties of an antipodal exponentially tapered antenna placed on the surface of a flow meter system in the UWB range is presented. It was observed that the water effect can be mitigated by shifting the antenna away from the pipe surface.

Chalcogenide Microsphere Fabricated From Fiber Tapers Using Contact With A High-Temperature Ceramic Surface, Pengfei Wang, Ganapathy Murugan, Gilberto Bramilla, Ming Ding, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The fabrication 1 and characterization of a 2 chalcogenide glass microsphere resonator has been demonstrated. 3 At wavelengths near 1550 nm, whispering gallery mode 4 resonances can be efficiently excited in a 74-μm-diameter 5 chalcogenide glass microsphere via evanescent coupling using a 6 tapered silica glass fiber with a waist diameter of circa 2 μm. 7 Resonances with Q-factors greater than 105 were observed. 8 Due to the high nonlinearity properties of the chalcogenide 9 material and the ease of fabrication process, chalcogenide 10 microspheres offer the potential for robustly assembled fully 11 integrated photonic devices. 12 Index Terms—Chalcogenide

Optimized Monopole And Dipole Antennas For Uwb Asset Tag Location Systems, Antoine Dumoulin, Matthias John, Max Ammann, Patrick Mcevoy

Articles

Miniaturized monopole and dipole antenna designs are reported with performances optimized for ultrawideband pulsed radio applications. The geometries are created using Bézier spline shapes, which have been refined with a genetic algorithm to simultaneously take account of both frequency- and time-domain criteria. Time-domain measurements of ultra wideband antennas with uniformly distributed energy across the full 3.1-10.6 GHz mask are reported for the first time and validate a new approach to minimization of pulse dispersion effects in the antenna designs.

Omnidirectional Circularly Polarised Microstrip Patch Antenna, Max Ammann, Adam Narbudowicz, Xiulong Bao

Articles

An omnidirectional circularly-polarised patch antenna is proposed. The antenna radiates right-handed circular-polarisation with an average axial ratio of 2.3 dB over a full 360° . A shallow diagonal CPW inset-feed was used to achieve good matching to the back-to-back coupled patches, providing a measured S11 < -15 dB at the centre frequency. The measured cross-polar performance is better than 13 dB and the realised gain variation is ~3 dB in the plane normal to the substrate.

Antipodal Vivaldi Antenna For Water Pipe Sensor And Telemetry, Giuseppe Ruvio, Domenico Gaetano, Max Ammann, Patrick Mcevoy

Articles

An antipodal Vivaldi antenna operates simultaneously for telemetry and sensing when placed conformally onto PVC pipes. Good radiation efficiency is realised and the antenna impedance matching remains stable when the pipe is empty or contains water. The Fidelity Factor performance based on an input Ultra Wideband Gaussian pulse is a suitable figure of merit to detect water presence. Different water levels and pipe conditions correspond to Fidelity Factors between 90% and 96%, which are a suitable dynamic range for sensing and the appropriate quality for pulse communications for remote monitoring.

A Microfiber Coupler Tip Thermometer, Ming Ding, Pengfei Wang, Gilberto Bramilla

Articles

A compact thermometer based on a broadband microfiber coupler tip is demonstrated. This sensor can measure a broad temperature interval ranging from room temperature to 1283 degrees C with sub-200 mu m spatial resolution. An average sensitivity of 11.96 pm/degrees C was achieved for a coupler tip with similar to 2.5 mu m diameter. This is the highest temperature measured with a silica optical fiber device. (C)2012 Optical Society of America

Characterising Domestic Electricity Consumption Patterns By Dwelling And Occupant Socio-Economic Variables: An Irish Case Study, Fintan Mcloughlin, Aidan Duffy, Michael Conlon

Articles

This paper examines the influence of dwelling and occupant characteristics on domestic electricity consumption patterns by analysing data obtained from a smart metering survey of a representative cross section of approximately 4,200 domestic Irish dwellings. A multiple linear regression model was applied to four parameters: total electricity consumption, maximum demand, load factor and time of use (ToU) of maximum electricity demand for a number of different dwelling and occupant socio-economic variables. In particular, dwelling type, number of bedrooms, head of household (HoH) age, household composition, social class, water heating and cooking type all had a significant influence over total domestic …

Evanescent Field Coupling Between Two Parallel Close Contact Sms Fiber Structures, Qiang Wu, Youqiao Ma, Jinhui Yuan, Yuliya Semenova, Pengfei Wang, Chongxiu Yu, Gerald Farrell

Articles

We proposed a novel optical coupling technique based on two parallel singlemode-multimode- singlemode (SMS) fiber structures. This technique utilizes one SMS structure to excite multiple cladding modes within an output singlemode fiber. The excited multiple cladding modes will be coupled to the input SMF in the second SMS structure by placing the two SMS fiber structures in parallel and in close contact each other. The coupled cladding modes will be re-coupled to a guided core mode by the second SMS fiber structure. Theoretical analysis for such technique was provided and experimentally we have achieved a pass band spectral response with …

Electrically Tunable Fabry-Perot Resonator Based On Microstructured Si Contaning Liquid Crystal, V. A. Tolmachev, V. A. Melnikov, A. V. Baldycheva, Kevin Berwick, T. S. Perova

Articles

We have built Fabry-Pérot resonators based on microstructured silicon and a liquid crystal. The devices exhibit tuning of the resonance peaks over a wide range, with relative spectral shifts of up to Δλ/λ = 10%. In order to achieve this substantial spectral shift, cavity peaks of high order were used. Under applied voltages of up to 15 V, a variation in the refractive index of the nematic liquid crystal E7 from Δn_LC = 0.12 to Δn_LC = 0.17 was observed. These results may have practical applications in the near-, mid and far-infrared range.

High-Q Bismuth-Silicate Nonlinear Glass Microsphere Resonators, Pengfei Wang, Ganapathy Murugan, Timothy Lee, Ming Ding, Gilberto Brambilla, Yuliya Semenova, Qiang Wu, Fumihito Koizumi, Gerald Farrell

Articles

The fabrication and characterization of a bismuth-silicate glass microsphere resonator has been demonstrated. At wavelengths near 1550 nm, high-modes can be efficiently excited in a 179-μm diameter bismuth-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of circa 2 μm. Resonances with Q-factors as high as were observed. The dependence of the spectral response on variations in the input power level was studied in detail to gain an insight into power-dependent thermal resonance shifts. Because of their high nonlinearity and high- factors, bismuth-silicate glass microspheres offer the potential for robustly assembled fully integrated all-optical …

High Temperature Performance Of An Optical Microfibre Coupler And Its Potential Use As A Sensor, Pengfei Wang, Ming Ding, Gilberto Bramilla, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The dependence of the transmission spectrum of an optical microfibre coupler at high temperatures is investigated experimentally. Results show a temperature sensitivity up to 36.59 pm/oC at a taper waist outer diameter of 2.5 μm; such a temperature-dependent performance can be utilized for temperature sensing up to 1000oC.

Optical Fibre Technology, Gerald Farrell

Articles

No abstract provided.

The Use Of A Fiber Comb Filter Fabricated By A Co2 Laser Irradiation To Improve The Resolution Of A Ratiometric Wavelength Measurement System, Pengfei Wang, Gilberto Brambilla, Ming Ding, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

An edge filter-based ratiometric wavelength measurement system is modeled and analyzed in this paper. The results confirm that the noise of input signal and photodetectors limits the resolution of the wavelength measurement system. The achievable resolution is calculated for a given noise level of the input signal and photodetectors' resolution. An improved ratiometric wavelength measurement system consisting of two fiber comb filters is presented both theoretically and experimentally, which performs coarse and fine wavelength measurements simultaneously. The resolution of the system is significantly improved to better than 5 pm while maintaining the potential for high measurement speed and wide measurable …

Germanium Microsphere High-Q Resonator, Pengfei Wang, Timothy Lee, Ming Ding, Anirban Dhar, Thomas Hawkins, Paul Foy, Yuliya Semenova, Qiang Wu, Jayanta Sahu, Gerald Farrell, John Ballato, Gilberto Brambilla

Articles

In this Letter, the fabrication and characterization of a microsphere resonator from the semiconductor germanium is demonstrated. Whispering gallery modes are excited in a 46 μm diameter germanium microsphere resonator using evanescent coupling from a tapered silica optical fiber with a waist diameter of 2 μm. Resonances with Q factors as high as 3.8×104 at wavelengths near 2 μm are observed. Because of their ultrahigh optical nonlinearities and extremely broad transparency window, germanium microsphere resonators offer the potential for optical processing devices, in particular at long wavelengths, such as around 2 μm.