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Articles 91 - 113 of 113
Full-Text Articles in Engineering
Parallel Operation Of Inverters And Active Power Filters In Distributed Generation System: A Review, Shafiuzzaman Khan Khadem, Malabika Basu, Michael Conlon
Parallel Operation Of Inverters And Active Power Filters In Distributed Generation System: A Review, Shafiuzzaman Khan Khadem, Malabika Basu, Michael Conlon
Articles
In this paper a technical review of parallel operation of power electronics inverters for load sharing conditions in distributed generation (DG) network is presented. Emphasis is given to parallel operation of Active Power Filters (APFs) as they are widely used to mitigate load current disturbances into DG networks. Discussions on recent advances in control strategies as applied to APFs are presented.
Investigation And Experimental Measurement Of Scissor Blade Cutting Forces Using Fiber Bragg Grating Sensors., Dean Callaghan, Ginu Rajan, Mark Mcgrath, Eugene Coyle, Yuliya Semenova, Gerald Farrell
Investigation And Experimental Measurement Of Scissor Blade Cutting Forces Using Fiber Bragg Grating Sensors., Dean Callaghan, Ginu Rajan, Mark Mcgrath, Eugene Coyle, Yuliya Semenova, Gerald Farrell
Articles
This paper investigated the application of FBG sensors in the measurement of scissor blade–tissue interaction forces. Sensor placement at the blade–tissue interaction site provides the basis for increased force measurement accuracy, without compromising the functionality of the instrument. This increased accuracy provided the foundation for in-depth analysis of the force components generated during typical scissor cutting cycles. Theoretical analysis and experimental investigation explored the decoupling of the major forces present during cutting. The isolation of tissue-fracture forces from inter-blade friction forces was carried out. This is useful as knowledge of the fracture properties of biological tissues can be diff cult …
Formation Of Infrared Windows Of Transparency In One-Dimensional Silicon Photonic Crystals, Anna Baldycheva, Vladmir A; Tolmachev, Tatiana S. Perova, Kevin Berwick
Formation Of Infrared Windows Of Transparency In One-Dimensional Silicon Photonic Crystals, Anna Baldycheva, Vladmir A; Tolmachev, Tatiana S. Perova, Kevin Berwick
Articles
The optical properties of three-component one-dimensional photonic crystal (1-D PC) structures were investigated by modeling them as two-component PCs with an additional regular t-layer, using the gap map approach and the transfer matrix method. Numerical results demonstrate that the introduction of the t-layer affects the properties of the high-order photonic band gaps, replacing them with transmission bands and creating regions of transparency over certain wavelength ranges. For the first time, a map of the transmission bands for a three-component 1-D PC was generated. This map constitutes a unique design tool for infrared optical filters for silicon-based photonic integrated …
Lead Silicate Glass Microsphere Resonators With Absorption-Limited Q, Pengfei Wang, Genapathy Murugan, Timothy Lee, Xian Feng, Yuliya Semenova, Qiang Wu, Wei Loh, Gilberto Brambilla, James Wilkinson, Gerald Farrell
Lead Silicate Glass Microsphere Resonators With Absorption-Limited Q, Pengfei Wang, Genapathy Murugan, Timothy Lee, Xian Feng, Yuliya Semenova, Qiang Wu, Wei Loh, Gilberto Brambilla, James Wilkinson, Gerald Farrell
Articles
We report the fabrication and characterization of a lead-silicate glass microsphere resonator. We show that at the wavelengths near 1555 nm high Q modes can be efficiently excited from a 109 μm diameter lead-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of 2 μm. Resonances with Q-factors as high as 0.9×107 were observed. This is very close to the theoretical material-limited Q-factor and is the highest Q-factor reported so far from a nonlinear glass microsphere.
Microstrip-Fed Wideband Circularly Polarized Printed Antenna, Xiulong Bao, Max Ammann, Patrick Mcevoy
Microstrip-Fed Wideband Circularly Polarized Printed Antenna, Xiulong Bao, Max Ammann, Patrick Mcevoy
Articles
A wideband circularly-polarized printed antenna is proposed, which employs an asymmetrical dipole and a slit in the ground plane which are fed by an L-shaped microstrip feedline using a via. The proposed antenna geometry is arranged so that the orthogonal surface currents, which are generated in the dipole, feedline and ground plane, have the appropriate phase to provide circular polarization. A parametric study of the key parameters is made and the mechanism for circular polarization is described. The measured results show that the impedance bandwidth is approximately 1.34 GHz (2.45 GHz to 3.79 GHz) and the 3 dB axial ratio …
Validated Real-Time Energy Models For Small-Scale Grid-Connected Pv-Systems, Lacour Ayompe, Aidan Duffy, Sarah Mccormack, Michael Conlon
Validated Real-Time Energy Models For Small-Scale Grid-Connected Pv-Systems, Lacour Ayompe, Aidan Duffy, Sarah Mccormack, Michael Conlon
Articles
This paper presents validated real-time energy models for small-scale grid-connected PV-systems suitable for domestic application. The models were used to predict real-time AC power output from a PV system in Dublin, Ireland using 30-min intervals of measured performance data between April 2009 and March 2010. Statistical analysis of the predicted results and measured data highlight possible sources of errors and the limitations and/or adequacy of existing models, to describe the temperature and efficiency of PV-cells and consequently, the accuracy of power prediction models. PV-system AC output power predictions using empirical models for PV-cell temperature and efficiency prediction showed lower percentage …
Protection Of Upqc Against The Load Side Short Circuits, Iurie Axente, Malabika Basu, Michael Conlon, Kevin Gaughan
Protection Of Upqc Against The Load Side Short Circuits, Iurie Axente, Malabika Basu, Michael Conlon, Kevin Gaughan
Articles
This study presents a protection scheme for protecting the series inverter of a unified power quality conditioner (UPQC). The proposed scheme protects the series inverter from overcurrents and overvoltages, which appear during short-circuit faults on the load side of the UPQC. The main protection element is a crowbar connected across the secondary of the series transformer and consists of a pair of antiparallel connected thyristors, which is governed by a simple Zener diode-based control circuit. In the case of an overvoltage, the crowbar short circuits the secondary of the transformer, thus removing the overvoltage and diverting the fault current from …
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
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 …
Double Quantum Dot Photoluminescence Mediated By Incoherent Reversible Energy Transport, S. Yu Kruchinin, A. V. Federov, A. V. Baranov, T. S. Perova, Kevin Berwick
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 …
Electron-Electron Scattering In A Double Quantum Dot: Effective Mass Approach, S. Yu. Kruchinin, A. V. Federov, A. V. Baranov, Tatiana Perova, Kevin Berwick
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.
Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels
Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels
Articles
The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10–33 W to generate a 1.2–1.6 kV 3.5 μs pulse. An argon discharge breakdown voltage of ∼768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5–10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in …
Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood
Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood
Articles
The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor …
Macrobending Fiber Loss Filter, Ratiometric Wavelength Measurement And Application, Qian Wang, Ginu Rajan, Gerald Farrell, Pengfei Wang, Yuliya Semenova, Thomas Freir
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.
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
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 …
Analysis Of Strain And Intermixing In Single-Layer Ge/Si Quantum Dots Using Polarized Raman Spectroscopy, Anna Baranov, A. V. Federov, Tatiana Perova, R. A. Moore, V. Yam, D. Bouchier, V. Le Thanh, Kevin Berwick
Analysis Of Strain And Intermixing In Single-Layer Ge/Si Quantum Dots Using Polarized Raman Spectroscopy, Anna Baranov, A. V. Federov, Tatiana Perova, R. A. Moore, V. Yam, D. Bouchier, V. Le Thanh, Kevin Berwick
Articles
The built-in strain and composition of as-grown and Si-capped single layers of Ge∕Si dots grown at various temperatures (460–800 °C) are studied by a comparative analysis of the Ge-Ge and Si-Ge modes in the polarized Raman spectra of the dots. A pronounced reduction of the strain and Ge content in the dots after deposition of the cap layer at low temperatures is observed, indicating that strain-induced Si diffusion from the cap layer is occurring. For large dots grown at 700–800 °C the observations are in agreement with a model of the Ge∕Si dot consisting of a Si-rich boundary region and …
Design Of One-Dimensional Composite Photonic Crystals With An Extended Photonic Band Gap, Vladimir Tolmachev, Kevin Berwick
Design Of One-Dimensional Composite Photonic Crystals With An Extended Photonic Band Gap, Vladimir Tolmachev, Kevin Berwick
Articles
A technique for photonic band gap (PBG) extension based on mixing photonic crystals with different lattice constants or filling factors is suggested. For the design of photonic crystals with maximal PBG extension the gap map imposition method is utilized. Gap maps for composite photonic crystals based on Si-air structures are calculated and used to predict optimal structures for fabrication.
Use Of Advanced Synthesis Tools In Teaching Vlsi Design, Kevin Berwick, Dominic Nardone
Use Of Advanced Synthesis Tools In Teaching Vlsi Design, Kevin Berwick, Dominic Nardone
Articles
No abstract provided.
The Effect Of The Internal Field On The Ir Absorption Spectra Of Small Particles In Case Of 3d, 2d And 1d Size Confinement, Igor I. Shaganov, Tatiana S. Perova, R. Alan Moore, Kevin Berwick
The Effect Of The Internal Field On The Ir Absorption Spectra Of Small Particles In Case Of 3d, 2d And 1d Size Confinement, Igor I. Shaganov, Tatiana S. Perova, R. Alan Moore, Kevin Berwick
Articles
The spectral properties of composite materials based on small particles under 1D, 2D, and 3D size confinement are described using a combination of dispersive internal field and effective media theory approaches. Calculations performed for a number of crystalline materials have shown that the peak position and intensity of the vibrational band of the material under conditions of 1D, 2D, and 3D size confinement are changed, whereas the bandwidth of the band remains the same. In the case of 3D confinement, the peak position of the spectrum of isolated “mesoparticles” ( ) appears to be very close to the intrinsic frequency …
An Explicit Mapping Between The Frequency Domain And The Time Domain Representations Of Nonlinear Systems, Marissa Condon, Rossen Ivanov
An Explicit Mapping Between The Frequency Domain And The Time Domain Representations Of Nonlinear Systems, Marissa Condon, Rossen Ivanov
Articles
Explicit expressions are presented that describe the input-output behaviour of a nonlinear system in both the frequency and the time domain. The expressions are based on a set of coefficients that do not depend on the input to the system and are universal for a given system. The anharmonic oscillator is chosen as an example and is discussed for different choices of its physical parameters. It is shown that the typical approach for the determination of the Volterra Series representation is not valid for the important case when the nonlinear system exhibits oscillatory behaviour and the input has a pole …
Design Criteria And Optical Characteristics Of One-Dimensional Photonic Crystals Based On Periodically Grooved Silicon, Vladimir Tolmachev, Tatiana Perova, Kevin Berwick
Design Criteria And Optical Characteristics Of One-Dimensional Photonic Crystals Based On Periodically Grooved Silicon, Vladimir Tolmachev, Tatiana Perova, Kevin Berwick
Articles
Photonic bandgap (PBG) regions have been calculated for periodically grooved Si structures, acting as a one-dimensional photonic crystal. The wavelength range of the PBG as a function of the ratio (DSi/A) is presented, where DSi is the width of the Si walls and A is the grooved silicon lattice constant. The influence of the parameter DSi, the refractive index of the space between the Si walls and the number of structure periods, m, on the forming of PBG regions is discussed. A good correlation between the calculated and the experimentally observed …
Study Of Structure And Quality Of Different Silicon Oxides Using Ftir And Raman Microscopy, C. Moore, T. S. Perova, B. Kennedy, Kevin Berwick, I. I. Shaganov, R. A. Moore
Study Of Structure And Quality Of Different Silicon Oxides Using Ftir And Raman Microscopy, C. Moore, T. S. Perova, B. Kennedy, Kevin Berwick, I. I. Shaganov, R. A. Moore
Articles
In this work, SiO2 and fluorine and phosphorous doped SiO2 thin films are investigated using FTIR and Raman techniques. FTIR spectroscopy was performed at normal and oblique incidence of the probe beam in transmission and reflection modes. The effect of polarisation and angle of incidence of the probe beam is examined for the case of reflection mode. Infrared spectra taken from doped oxides show that the structure changes with the passage of time. Alternate methods to calculate the thickness of the doped film are therefore discussed. Infrared spectra of electron beam evaporated oxides give valuable information on their …
Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick
Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick
Articles
Precise chemical analysis (PCA) was developed to allow the study of non-interconnected atoms on crystalline semiconductor surfaces, such as those produced during rapid thermal processing (RTP) of silicon and electron beam lithography on gallium arsenide (GaAs). The PCA method is based on selectively dissolving the different components present on the semiconductor surface using preferential etchant solutions. After etching, the etchant solution, containing the etched component, is analyzed by a photometric technique. In this paper, we present photometric measurements of the amount of “free” (non-interconnected) atoms that remain on semiconductor surfaces following electron beam and RTP processing. In this context, “free” …
Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble
Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble
Articles
proximity rapid thermal diffusion (RTD). A compressive stress was found on the whole silicon wafer after 15 s RTD. After 165 s RTD, the distribution of the stress across the wafer was found to be different: compressive at the edge and tensile at the middle. Thermal stress was relieved in the RTD wafers via slip dislocations. These slip dislocations were observed in the product wafers using optical microscopy. Slip lines propagated from the wafer edge to the wafer centre in eight preferred positions of maximum induced stress. The thermally induced stress and the slip dislocation density increased with time spent …