Engineering Commons^™

A Study Of The Effect Of The Position Of An Edge Filter Within A Ratiometric Wavelength Measurement System, Qiang Wu, Pengfei Wang, Yuliya Semenova, Gerald Farrell

Articles

The effect of the position of an edge filter within a ratiometric wavelength measurement system was investigated based on three cases: (1) the reflected fibre Bragg grating (FBG) signal passes through both the reference arm and the edge filter arm, (2) the reflected FBG signal is connected directly to the edge filter arm and does not pass through the reference arm, (3) the edge filter sits in line with the FBG and thus the source power is filtered prior to reaching the FBG. Both numerical simulations and experimental results show that cases 1 and 2 have similar system performance whilst …

Strain Sensor Based On A Pair Of Single-Mode-Multimode-Single-Mode Fiber Structures In A Ratiometric Power Measurement Scheme, Agus Hatta, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The strain and temperature dependencies of a step-index single-mode–multimode–single-mode (SMS) fiber structure are investigated numerically and experimentally. For intensity-based strain measurement using a single SMS fiber structure, at a selected wavelength, it is found that there is a high strain dependence, but also a temperature dependence that will induce strain measurement error. To minimize the temperature-induced strain measurement error, two SMS fiber structures are proposed and demonstrated in a ratiometric power measurement scheme; one SMS structure acts as the strain sensor, and the other SMS structure acts as the temperature monitor. The extracted temperature information is used to determine a …

Study Of The Effect Of Source Signal Bandwidth On Ratiometric Wavelength Measurement, Qiang Wu, Yuliya Semenova, Ginu Rajan, Pengfei Wang, Gerald Farrell

Articles

We derive an analytic equation for a ratiometric wavelength measurement system and analyze the influence of the optical source signal bandwidth. Our investigation shows that in a particular optical sensing system, the higher the bandwidth of the optical signal, the better resolution the system will achieve. Experiments based on two types of optical signals (output signal of a tunable laser and a fiber Bragg grating) were carried out, and experimental results verified both the simulation results and the theoretical analysis.

Temperature Performance Of A Macrobending Single-Mode Fiber-Based Refractometer, Pengfei Wang, Yuliya Semenova, Qiang Wu, Zie Zheng, Gerald Farrell

Articles

The temperature dependence of polarization-dependent loss (PDL) for a macrobending standard single-mode fiber (SMF28) is investigated both theoretically and experimentally. The experimental results show an overall agreement with the proposed theoretical model over a temperature range from 0 C to 70 C. An SMF28-based edge filter is used as an example regarding temperature- dependent PDL performance. It is shown that the temperature variations have a significant influence on the polarization dependence of macrobending loss, and further impact on such a fiber bend loss edge filter used in a wavelength measurement application. It is also concluded that by using the proposed …

Simple Design Technique For A Triangular Fbg Filter Based On A Linearly Chirped Grating, Qiang Wu, Gerald Farrell, Yuliya Semenova

Articles

A novel and simple design technique for triangular spectrum response of fibre Bragg grating (FBG) is pre- 21 sented based on a linear chirped grating. It is shown that this method is fast and can give a straightfor- 22 ward solution to meet a design target. The numerical simulation examples verified the effectiveness of 23 the design method. A general approach to design for multichannel triangular spectral responses for 24 FBG filters is proposed, which provides a solution that achieves a minimum change of refractive index 25 for the fibre.

Dissociative Cdse/Zns Quantum Dot-Molecule Complex For Luminescent Sensing Of Metal Ions In Aqueous Solutions, A. V. Baranov, A. O. Orlova, V. G. Maslov, Yu. A. Toporova, E. V. Ushakova, A. Federov, M. V. Artemyev, T. S. Perova, Kevin Berwick

Articles

The optical properties of dissociative luminescent sensors based on a complex consisting of highly luminescent hydrophobic core/shell CdSe/ZnS quantum dots (QDs) and 1-(2-pyridilazo)-2-naphtol (PAN) molecules in organic solutions and a polymer film are reported. It is demonstrated, using Ni²⁺ and Co²⁺ ions as an illustrative example, that the QD/PAN sensor may have applications in the quantitative luminescent sensing of metal ions in aqueous solutions.

Double Quantum Dot Photoluminescence Mediated By Incoherent Reversible Energy Transport, S. Yu Kruchinin, A. V. Federov, A. V. Baranov, T. S. Perova, Kevin Berwick

Articles

We present a theoretical study of the stationary photoluminescence of two, direct-gap, semiconductor nanocrystals, taking into account electronic excitation energy-transfer processes due to electrostatic interaction. The results obtained here allow for the incoherent reversible energy transport that occurs when the intraband relaxation rate in a quantum dot acceptor is comparable to, or less than, the energy-transfer rate. We investigate the secondary emission of two different electronic level schemes that can be realized experimentally, obtain analytical expressions for the luminescence differential cross section, and perform an analysis of its spectrum. It is shown that when excitation is not in resonance with …

The Fractal Market Hypothesis: Applications To Financial Forecasting, Jonathan Blackledge

Books/Book chapters

No abstract provided.

Audio Thumbnail Generation Of Irish Traditional Music, Cillian Kelly, Mikel Gainza, David Dorran, Eugene Coyle

Conference papers

An approach is presented which generates an audio thumbnail of Irish traditional music. An audio thumbnail is consered to be the most representative segment of the music. For popular music, the chorus is considered to be an ideal audio thumbnail, however in Irish Traditional Music there is no chorus. An Irish Traditional tune consists of tow or mor short structural segments called parts. Parts are repeated to extend the tuen, and the tune itself is also repeated once or more in its entirety. To further extend a performance, tunes are concatenated to form a set of tuens. As a result, …

On The Use Of A Dynamic Hybrid Tempo Detection Model For Beat Tracking, Mikel Gainza

Conference papers

In this paper, an approach that estimates the times at which musical beats occur is presented. The system uses a hybrid multi-band decomposition in order to estimate the music tempo. Following this, beat events are tracked by using a dynamic programming approach, which is updated by using short time tempo estimates. The hybrid decomposition is used in order to calculate the tempo by using different onset detection functions in different frequency bands. In addition, a method that estimates which frequency bands provide reliable periodicities is also presented. The accuracy of the model is evaluated by comparing the presented system against …

Electric Field Induced Biaxiality And The Electro-Optic Effect In A Bent-Core Nematic Liquid Crystal, Mamatha Nagaraj, Yuri Panarin, U. Manna, J. K. Vij, C. Keith, C. Tschierske

Articles

We report the observation of a biaxial nematic phase in a bent-core molecular system using polarizing microscopy, electro-optics, and dielectric spectroscopy, where we find that the biaxiality exists on a microscopic scale. An application of electric field induces a macroscopic biaxiality and in consequence gives rise to electro-optic switching. This electro-optic effect shows significant potential in applications for displays due to its fast high-contrast response. The observed electro-optic switching is explained in terms of the interaction of the ferroelectric clusters with the electric field. © 2010 American Institute of Physics.

E-Fraud Prevention Based On The Self-Authentication Of E-Documents, Jonathan Blackledge, Eugene Coyle

Conference papers

We consider a method for preventing e-Fraud in which a binary image is encrypted with a floating point cipher using a convolution operation and the output quantized into a 1-bit array generating a binary image ciphertext. The output is then ‘embedded’ in a host image to hide the encrypted information. Embedding is undertaken either in the lowest 1-bit layer or multiple 1-bit layers. Decryption is accomplished by: (i) extracting the binary image from the host image; (ii) correlating the result with the original cipher. In principle, any cipher generator can be used for this purpose and the method has been …

Liquid Crystal Display Modes In A Nontilted Bent-Core Biaxial Smectic Liquid Crystal, Mamatha Nagaraj, Yuri Panarin, J. K. Vij, C. Keith, C. Tschierske

Articles

Liquid crystal display (LCD) modes associated with the rotation of the secondary director in nontilted, biaxial smectic phase of an achiral bent-core compound are demonstrated. For LCDs, we find that at least four display modes are possible using SmAPA phase of the studied material, in which the minor directors in adjacent layers are aligned antiferroelectrically. The advantages of these modes include low driving field (1–2 V/ µm), high contrast ratio 1000:1, relatively fast switching time of 0.5 ms and continuous gray scale. The molecular short axis or the polar axis in a negative dielectric, biaxial material is oriented by the …

Simulation Procedure For The Co-Optimization Of Photovoltaic Water Pumping Systems., Brian Norton

Articles

Abstract: Photovoltaic (PV)-powered centrifugal water pumping systems have been modelled based on field experience and analysis of long-term measured performance of several installed PV-powered water pumping systems. This paper presents detailed modelling of a PV array, an inverter, a three-phase induction motor, a centrifugal pump, a well, a storage tank, an overflow controller, and an integrated reverse osmosis desalination unit. The component models were validated using both laboratory measurements and long-term monitored data. All system components have been modelled separately, and the system was modelled in TRNSYS. The models are capable of simulating grid-connected, diesel-powered, and PV-powered water pumping systems, …

Passive All-Fiber Wavelength Measurement Systems: Performance Determination Factors, Ginu Rajan, Yuliya Semenova, Agus Hatta, Gerald Farrell

Books/Book Chapters

No abstract provided.

Humidity Sensor Based On A Photonic Crystal Fiber Interferometer, Jinesh Mathew, Yuliya Semenova, Ginu Rajan, Gerald Farrell

Articles

A photonic crystal fiber interferometer that operates in reflection mode for humidity detection is presented for the first time which has the advantage that it does not require the use of any hygroscopic material. The fabrication of the sensor head is therefore simple since it only involves cleaving and splicing. The all-silica nature of the device has the potential for many applications.

Electron-Electron Scattering In A Double Quantum Dot: Effective Mass Approach, S. Yu. Kruchinin, A. V. Federov, A. V. Baranov, Tatiana Perova, Kevin Berwick

Articles

We present a theoretical description of the first-order scattering of interacting electrons and holes in a double quantum dot. Assuming infinitely high walls, strong confinement, and a two-band approximation, we derive general expressions for the two-particle matrix elements of the screened Coulomb potential. We also determine the selection rules for different scattering channels and consider special cases where the corresponding matrix elements can be represented by simple analytical expressions. Numerical calculations of the matrix elements and an analysis of their dependence on the geometrical and material parameters of the double quantum dot have also been performed.

The Size Ellect On The Infrared Spectra Of Condensed Media Under Conditions Of Id, 2d And 3d Dielectric Confinement, Igor I. Shaganov, Tatiana S. Perova, Vasily A. Melnikov, Kevin Berwick

Articles

A general expression for the dielectric loss spectrum of an absorbing composite medium was obtained from a Maxwell-Garnett general equation. This expression was simplified for the cases of one, two and three dimensional dielectric confinement in both ordered and disordered thin layers, rods (wires) and spheres of absorbing medium which are considered as mesoparticles or mesoscopic molecules. This theoretical approach was verified experimentally using high purity organic liquids with strong absorption bands in the infrared range. Three organic liquids, namely benzene, chloroform and carbon disulphide, were measured in various dielectric confinement configurations using Fourier Transform Infrared (FTIR) spectroscopy with a …

Experiences Of Assessment Using Multiple Choice Questions On Advanced Modules Taken By Level 8 And Level 9 Engineering Students, Aidan O'Dwyer

Conference papers

This contribution evaluates the use of multiple-choice questions, in both formative and summative assessment modes, on advanced modules taken by Level 8 and Level 9 engineering students, over the past two academic years. Assessment data, and student experiences with the assessment methods, are reported and analysed.

Estimating The Yield Of Micro Wind Turbines In An Urban Environment: A Methodology, Keith Sunderland, Michael Conlon

Conference papers

Micro wind turbines currently have the majority share of micro (electricity) generation installations in Ireland. These technologies are being installed predominantly in rural environments, and current applications to the Distribution Services Operator (DSO) for connection of all types of micro generator stand at less than 500. Poor market dissemination of information and research findings compounded with poor options for spill payment - as well as onerous planning restrictions do not –it appears - create a platform conducive to encouraging development in this market.

This paper outlines the complexities associated with evaluating the wind resource within an urban environment and investigates …

On The Appearance Of A Positive Real Pole In The Results Of Glottal Closed Phase Linear Prediction, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

Often when performing glottal closed phase covariance linear prediction, a positive real pole can appear in the resulting filter transfer function. The commonly adopted approach is to discard this pole, as it does not fit with the usual model of the all-pole vocal tract filter. However, this real pole describes some aspect of the speech signal; this paper provides a novel perspective on its occurrence. This viewpoint has a useful implication to the speech community, especially from the perspective of fitting a glottal pulse to the inverse filtered signal, as the real pole describes the return phase of the glottal …

Towards A Method To Determine The Glottal Formant Parameters Of Voiced Speech Without Time-Domain Reference, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

This paper presents an approach to estimate the glottal formant parameters of the voicing source in the frequency-domain. The method is based on a simplified pole-zero interpretion of the prevalent Liljencrants-Fant (LF) model of glottal flow, and gives approximations for a broad range of pulses shapes. An advantage of the method is that, unlike other methods, it does not rely on time-domain references.

Interactive Music Archive Access System, Martin Gallagher, Mikel Gainza, 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 timescale modification, …