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Full-Text Articles in Engineering

V-Shaped Electro-Optic Response Observed In A Chiral Ferroelectric Smectic Liquid Crystal, V. Manjuladevi, Yuri Panarin, Jang-Kun Song, B. K. Sadashiva Jan 2008

V-Shaped Electro-Optic Response Observed In A Chiral Ferroelectric Smectic Liquid Crystal, V. Manjuladevi, Yuri Panarin, Jang-Kun Song, B. K. Sadashiva

Articles

We report on the observation of V-shaped switching in a ferroelectric liquid crystal cell over a wide range of temperatures. Results of the optical transmittance in the visible region give us the helical pitch for various temperatures of the ferroelectric liquid crystalline compound used. We show that the helical pitch, in addition to the spontaneous polarization (PS) and thickness of the alignment layer of the cell, is an important factor in giving V-shaped switching. A longer or helical compensated mixture gives a better V-shaped switching. © 2008 American Institute of Physics.


Experimental Study Of High-Temperature Smectic-C*F12 Phase In Chiral Smectic Liquid Crystals That Exhibit Phase-Sequence Reversal, K. L. Sandhya, J. K. Song, Yuri Panarin, J. K. Vij, S. Kumar Jan 2008

Experimental Study Of High-Temperature Smectic-C*F12 Phase In Chiral Smectic Liquid Crystals That Exhibit Phase-Sequence Reversal, K. L. Sandhya, J. K. Song, Yuri Panarin, J. K. Vij, S. Kumar

Articles

We report the results of an experimental study of a recently observed phase sequence reversal of smectic-C*FI2 [SmC*(qT=1/2); a four layer antiferroelectric] phase appearing in the temperature range above the smectic-C* (SmC*) phase from the results of optical birefringence, spontaneous polarization, selective reflection, conoscopy, and dielectric spectroscopy. The SmC*FI2 phase is observed in an antiferroelectric liquid crystalline compound, 10OHF, in a temperature range above that of SmC*A phase and is found to be thermodynamically monotropic, i.e., it appears only upon cooling from SmC*A phase. This is also unstable as if it is once transformed to SmC* by the application of …


Extended Nonnegative Tensor Factorisation Models For Musical Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle Jan 2008

Extended Nonnegative Tensor Factorisation Models For Musical Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle

Articles

Recently, shift-invariant tensor factorisation algorithms have been proposed for the purposes of sound source separation of pitched musical instruments. However, in practice, existing algorithms require the use of log-frequency spectrograms to allow shift invariance in frequency which causes problems when attempting to resynthesise the separated sources. Further, it is difficult to impose harmonicity constraints on the recovered basis functions. This paper proposes a new additive synthesis-based approach which allows the use of linear-frequency spectrograms as well as imposing strict harmonic constraints, resulting in an improved model. Further, these additional constraints allow the addition of a source filter model to the …


Analysis Of Financial Data Using Non-Negative Matrix Factorization, Ruairí De Fréin, Konstantinos Drakakis, Scott Rickard, Andrzej Cichocki Jan 2008

Analysis Of Financial Data Using Non-Negative Matrix Factorization, Ruairí De Fréin, Konstantinos Drakakis, Scott Rickard, Andrzej Cichocki

Articles

We apply Non-negative Matrix Factorization (NMF) to the prob-lem of identifying underlying trends in stock market data. NMF is arecent and very successful tool for data analysis including image andaudio processing; we use it here to decompose a mixture a data, thedaily closing prices of the 30 stocks which make up the Dow Jones In-dustrial Average, into its constitute parts, the underlying trends which govern the financial marketplace. We demonstrate how to impose ap-propriate sparsity and smoothness constraints on the components of thedecomposition. Also, we describe how the method clusters stocks to-gether in performance-based groupings which can be used for …


Investigation On The Performance Of Upqc-Q For Voltage Sag Mitigation And Pq Improvement At A Critical Load Point, Malabika Basu, S. P. Das, Gopal Dubey Jan 2008

Investigation On The Performance Of Upqc-Q For Voltage Sag Mitigation And Pq Improvement At A Critical Load Point, Malabika Basu, S. P. Das, Gopal Dubey

Articles

The unified power quality conditioner (UPQC) is one of the major custom power solutions, which is capable of mitigating the effect of supply voltage sag at the load end or at the point of common coupling (PCC) in a distributed network. It also prevents the propagation of the load current harmonics to the utility and improves the input power factor of the load. The control of series compensator (SERC) of the UPQC is such that it injects voltage in quadrature advance to the supply current. Thus, the SERC consumes no active power at steady state. The other advantage of the …


Covert Encryption And Document Authentication Using Texture Coding, Jonathan Blackledge, Mary Hallot Jan 2008

Covert Encryption And Document Authentication Using Texture Coding, Jonathan Blackledge, Mary Hallot

Articles

With the improvements in the quality of Commercial-Off-The-Shelf (COTS) printing and scanning devices, the ability to counterfeit documents has become a widespread problem. Consequently, there has been an increasing demand to develop digital watermarking techniques which can be applied to both electronic and printed images (and documents) that can be authenticated, prevent unauthorized copying and withstand abuse and degradation. In this paper , a new approach to digital watermarking is presented and a range of possible applications are considered. The process is defined by using concepts and techniques borrowed from Cryptography. It is based on computing a 'scramble image' by …


Temperature Dependence Of A Macrobending Edge Filter Based On A High-Bend Loss Fiber, Pengfei Wang, Ginu Rajan, Yuliya Semenova, Gerald Farrell Dec 2007

Temperature Dependence Of A Macrobending Edge Filter Based On A High-Bend Loss Fiber, Pengfei Wang, Ginu Rajan, Yuliya Semenova, Gerald Farrell

Articles

The temperature dependence of a macrobending bare fiber based edge filter is investigated both theoretically and experimentally. The fiber used is a high bend loss fiber, type 1060XP. The experimental results show a good agreement with the proposed theoretical model over a temperature range from 0 to 80oC. It is shown that the strong temperature dependence of a high-bend loss fiber has a significant influence on the performance of a fiber edge filter used in a wavelength measurement application. However it is also concluded that such a temperature dependent performance can be beneficially utilized in a fiber temperature sensing application.


A Coupled Fluid-Structure Model Of A Therapeutic Ultrasound Angioplasty Wire Waveguide, Graham Gavin, Finbar Dolan, M.S. Hashmi, Garrett Mcguinness Dec 2007

A Coupled Fluid-Structure Model Of A Therapeutic Ultrasound Angioplasty Wire Waveguide, Graham Gavin, Finbar Dolan, M.S. Hashmi, Garrett Mcguinness

Articles

Ultrasonic longitudinal displacements, delivered to the distal tips of small diameter wire waveguides, have been shown to be capable of disrupting complicated atherosclerotic plaques during vascular interventions. These ultrasonic displacements can disrupt plaques by direct contact ablation but also by pressure waves, associated cavitation and acoustic streaming developed in the surrounding blood and tissue cavities. The pressure waves developed within the arterial lumen appear to play a major role but are complex to predict as they are determined by the distal tip output of the wire waveguide (both displacement and frequency), the geometric features of the waveguide tip and the …


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 …


Thermal Testing Of Building Insulation Materials, Eoghan Frawley, David Kennedy Nov 2007

Thermal Testing Of Building Insulation Materials, Eoghan Frawley, David Kennedy

Articles

This article explores the testing of building insulation materials and the development of a suitable testing apparatus.


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 …


Resolution Investigation Of A Ratiometric Wavelength Measurement System, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell Sep 2007

Resolution Investigation Of A Ratiometric Wavelength Measurement System, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell

Articles

Theoretical analysis and experimental investigations are presented on the resolution of a ratiometric wavelength measurement system. Theoretical modeling indicates that the resolution of a ratiometric wavelength measurement system is determined by the signal-to-noise ratio of the input signal and the noise of the photodetectors associated with optical-to-electronic conversion. For experimental verification, a ratiometric system employing a macrobending standard single-mode fiber is developed and corresponding results are in good agreement with the theoretical prediction.


Treating Water Contamination Using Ultraviolet Radiation To Control Cryptosporidium And E.Coli, Michael O'Hehir, David Kennedy, Thomas Dunphy Aug 2007

Treating Water Contamination Using Ultraviolet Radiation To Control Cryptosporidium And E.Coli, Michael O'Hehir, David Kennedy, Thomas Dunphy

Articles

Concerns about the quality of drinking water in Ireland have come into sharp focus with the recent Cryptosporidium outbreak in Galway City. This article looks at how ultraviolet radiation can offer a potential solution in the control of Cryptosporidium contamination.


Effect Of Snr Of Input Signal On The Accuracy Of A Ratiometric Wavelength Measurement System, Ginu Rajan, Qian Wang, Gerald Farrell, Yuliya Semenova, Pengfei Wang May 2007

Effect Of Snr Of Input Signal On The Accuracy Of A Ratiometric Wavelength Measurement System, Ginu Rajan, Qian Wang, Gerald Farrell, Yuliya Semenova, Pengfei Wang

Articles

The impact of a change in SNR of the input signal on the accuracy of a ratiometric wavelength measurement system is studied. The variation of the output ratio of the system due to the change in SNR of the input signal is modeled and the experimental investigation has been carried out, and both indicate that the accuracy is influenced significantly by variations in the SNR of the input signal. The demonstration example shows a wavelength shift of 0.055 nm when the SNR of the input signal varies from 47 dB to 42 dB (the measurable range is from 1500 nm …


Polarization Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell Apr 2007

Polarization Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell

Articles

Polarization dependence of bend loss caused by the polymer coating layer for a standard singlemode fiber (SMF28) is investigated theoretically and experimentally. Bend loss for SMF28 for both the TE and TM mode is calculated separately. Normalized polarization dependent loss is proposed for the characterization of the polarization sensitivity of bend loss for different bend radii. Corresponding experimental tests are presented, which agree with the theoretical results. Both the theoretical and experimental results show that the polymer coating layer has a significant influence on the polarization dependence of bend loss.


Performance Characteristics Of A Therapeutic Ultrasound Wire Waveguide, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. Hashmi Mar 2007

Performance Characteristics Of A Therapeutic Ultrasound Wire Waveguide, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. Hashmi

Articles

Therapeutic ultrasound angioplasty has been investigated, clinically, by a number of researchers and represents a potentially promising therapy for the treatment of atherosclerotic lesions. To date, there has been no detailed analysis of the effect of mechanical design parameters, such as wire geometry or damping characteristics, on wire waveguide performance. An apparatus capable of delivering therapeutic ultrasound down small diameter nickel–titanium (NiTi) wire waveguides is described. The output peak-to-peak (p–p) displacements at the distal tip of a 1.0mm diameter waveguide were measured experimentally, by means of an optical microscope and image analysis software. The output was measured for a range …


An Optimized Macrobending Fiber Based Edge Filter, Pengfei Wang, Gerald Farrell, Qian Wang, Ginu Rajan Jan 2007

An Optimized Macrobending Fiber Based Edge Filter, Pengfei Wang, Gerald Farrell, Qian Wang, Ginu Rajan

Articles

An optimized all-fiber edge filter is developed, based on a one-turn macrobending bare fiber structure. The discrimination range (DR) is 16.32 dB over a wavelength range from 1500 to 1600 nm, which can be employed for wavelength measurement applications. It offers a simpler structure compared to the previously developed macrobending fiber loss edge filters, without an increase in the polarization dependent loss (PDL).


An Optimized Macrobending Fiber Based Edge Filter, Pengfei Wang, Gerald Farrell, Qian Wang, Ginu Rajan Jan 2007

An Optimized Macrobending Fiber Based Edge Filter, Pengfei Wang, Gerald Farrell, Qian Wang, Ginu Rajan

Articles

An optimized all-fiber edge filter is developed, based on a one-turn macrobending bare fiber structure. The discrimination range is 16.32 dB over a wavelength range from 1500 to 1600 nm, which can be employed for wavelength measurement applications. It offers a simpler structure compared to the previously developed macrobending fiber loss edge filters, without an increase in the polarization-dependent loss.


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


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.


Effect Of Polarisation-Dependent Loss On The Performance Accuracy Of A Ratiometric Wavelength Measurement System, Ginu Rajan, Qian Wang, Yuliya Semenova, Gerald Farrell, Pengfei Wang Jan 2007

Effect Of Polarisation-Dependent Loss On The Performance Accuracy Of A Ratiometric Wavelength Measurement System, Ginu Rajan, Qian Wang, Yuliya Semenova, Gerald Farrell, Pengfei Wang

Articles

The polarisation-dependent loss (PDL) of a ratiometric wavelength measurement system and its influence on system's accuracy are investigated theoretically and experimentally. The PDL of a ratiometric system and the corresponding power ratio fluctuation is modelled, from which the accuracy of the measured wavelength can be estimated. An all-fibre wavelength measurement system is built to allow comparison of modelled and actual results. The measured ratio variation lies within the estimated limits. The measured wavelength error reaches about 1.41 plusmn 0.09 nm at 1550 nm in the demonstrated example (with an edge filter of average slope 0.22 dB/nm), which indicates the significant …


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 …


Small Patch/Slot Antenna With 53% Input Impedance Bandwidth, Xiulong Bao, Max Ammann Jan 2007

Small Patch/Slot Antenna With 53% Input Impedance Bandwidth, Xiulong Bao, Max Ammann

Articles

A small microstrip patch/slot antenna, which achieves a very large bandwidth on a relatively thin substrate (about 0.01lambda0), is presented. The performance is achieved by employing a combination of annular-ring loading on the patch radiator and the use of a crossed-slot for miniaturisation. An additional ring-slot in the ground plane is used to produce the wideband characteristics of the antenna. Simulated and measured results indicate that a 53% fractional impedance bandwidth is achieved with respect to the centre frequency of 1.409 GHz and the size of the antenna is reduced by 50% compared to the conventional circular patch antenna with …


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 …


A Novel Processing Route For The Production Of Nanoparticulate Zinc Oxide, Declan Mccormack, Grainne Duffy, Suresh Pillai Jan 2007

A Novel Processing Route For The Production Of Nanoparticulate Zinc Oxide, Declan Mccormack, Grainne Duffy, Suresh Pillai

Articles

Zinc oxide nanoparticles have been processed from a novel isophthalate
precursor. In contrast to those processed from an oxalate precursor, this
material exhibits three-dimensional, non-directional aggregation behaviour.
Such non-directional aggregation of uniaxial crystallites may allow for the
production of structures with a higher proportion of catalytically active
surfaces than can be prepared through conventional sol–gel methods. XRD,
FTIR, TEM and SEM were used to characterize the synthesized materials.
Zinc oxide particles synthesized by using isophthalic acid
(C6H4-1,3-(COOH)2) are found to be slightly smaller than the previously
reported materials prepared through chelation with oxalic acid
(H2C2O2·2H2O).


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.


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 …


The Effect Of The Rate Of Precursor Production On The Purity And Aggregation Morphology Of Nanoparticulate Zinc Oxide, Grainne Duffy, Suresh Pillai, Declan Mccormack Jan 2007

The Effect Of The Rate Of Precursor Production On The Purity And Aggregation Morphology Of Nanoparticulate Zinc Oxide, Grainne Duffy, Suresh Pillai, Declan Mccormack

Articles

The synthesis of zinc oxide through the decomposition of a solid oxalate precursor was
investigated. It was found that the rate of preparation of the precursor had a quantitative effect on
the morphology and extent of surface ligation of particles produced; contrary to our expectations,
it was found that the slow combination of reagents led to a less pure product. It has been
determined that this time dependence mimics the variation of reactant ratios. Zinc oxide particles
were produced from a number of reactant ratios, and were characterised by TEM, XRD, FT-IR
and DSC. It was found that the size …


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 …


Polarisation Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell Jan 2007

Polarisation Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell

Articles

Polarization dependence of bend loss caused by the polymer coating layer for a standard singlemode fiber (SMF28) is investigated theoretically and experimentally. Bend loss for SMF28 for both the TE and TM mode is calculated separately. Normalized polarization dependent loss is proposed for the characterization of the polarization sensitivity of bend loss for different bend radii. Corresponding experimental tests are presented, which agree with the theoretical results. Both the theoretical and experimental results show that the polymer coating layer has a significant influence on the polarization dependence of bend loss.