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159,649 full-text articles. Page 4739 of 4749.

A Liquid Crystal Coated Tapered Photonic Crystal Fiber Interferometer, Ginu Rajan, Sunish Mathews, Gerald Farrell, Yuliya Semenova 2010 Technological University Dublin

A Liquid Crystal Coated Tapered Photonic Crystal Fiber Interferometer, Ginu Rajan, Sunish Mathews, Gerald Farrell, Yuliya Semenova

Articles

An experimental investigation on liquid crystal coated tapered photonic crystal fiber (PCF) interferometer is presented in this paper. The interferometer is fabricated by tapering a small section of a PCF by collapsing the air holes and thinning down the air hole collapsed region to a micron size. Several interferometers are fabricated from different types of photonic crystal fibers and the temperature dependence studies are carried out to select an intrinsically temperature insensitive interferometer that can be used with liquid crystal (LC) materials. The properties of the LC materials to be used with the tapered PCF interferometers are also discussed. Temperature ...


Temperature Performance Of A Macrobending Single-Mode Fiber-Based Refractometer, Pengfei Wang, Yuliya Semenova, Qiang wu, Zie Zheng, Gerald Farrell 2010 Technological University Dublin

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 ...


Study Of The Effect Of Source Signal Bandwidth On Ratiometric Wavelength Measurement, Qiang wu, Yuliya Semenova, Ginu Rajan, Pengfei Wang, Gerald Farrell 2010 Technological University Dublin

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.


A Voltage Sensor Based On A Singlemode-Multimode-Singlemode Fiber Structure, Agus Hatta, Yuliya Semenova, Ginu Rajan, Gerald Farrell 2010 Technological University Dublin

A Voltage Sensor Based On A Singlemode-Multimode-Singlemode Fiber Structure, Agus Hatta, Yuliya Semenova, Ginu Rajan, Gerald Farrell

Articles

A voltage sensor based on a singlemode-multimodesinglemode (SMS) fiber structure, attached to a piezoelectric (PZT), utilized in a ratiometric optical power measurement scheme is proposed. The elongation of the PZT due to an applied voltage induces a strain on the SMS fiber structure and in turn results in a change in the transmission loss response of the SMS fiber structure. It is found that at selected wavelengths, a strong voltage dependence for the transmission loss of the SMS fiber structure can be achieved. The voltage information can be obtained from the power ratio of the system, assuming the system is ...


Simple Design Technique For A Triangular Fbg Filter Based On A Linearly Chirped Grating, Qiang Wu, Gerald Farrell, Yuliya Semenova 2010 Technological University Dublin

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.


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 2010 Technological University Dublin

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 ...


Experimental Analysis And Demonstration Of A Low Cost Fibre Optic Temperature Sensor System For Engineering Applications, Ginu Rajan, Yuliya Semenova, Jinesh Mathew, Gerald Farrell 2010 Technological University Dublin

Experimental Analysis And Demonstration Of A Low Cost Fibre Optic Temperature Sensor System For Engineering Applications, Ginu Rajan, Yuliya Semenova, Jinesh Mathew, Gerald Farrell

Articles

An epoxy packaged surface mountable fibre temperature sensor for engineering applications is presented in this paper. The temperature sensor is based on a macro-bend single-mode fibre loop employed in a ratiometric power measurement scheme and has a linear characteristic with temperature at a fixed wavelength and bend radius. The sensor head consists of a single turn of a bare bend sensitive single-mode fibre with an applied absorption coating. The temperature of the sensor head is varied up to 80 0C and the linearity of the response is studied with different applied absorption coatings. The sensor head is packaged in a ...


Electron-Electron Scattering In A Double Quantum Dot: Effective Mass Approach, S. Yu. Kruchinin, A. V. Federov, A. V. Baranov, Tatiana Perova, Kevin Berwick 2010 Saint Petersburgh State University of Information Technologies, Mechanics and Optics

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.


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 2010 State University of Informational Technologies,Mechanics and Optics, St. Petersburgh

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.


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 2010 Vavilov State Optical Institute, St. Petersburg

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 2010 St. Petersburgh State University of Information Technologies, Mechanics and Optics

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 ...


Frustrated Drift Of An Anchored Scroll-Wave Filament And The Geodesic Principle, Marcel Wellner, Christian W. Zemlin, Arkady M. Pertsov 2010 Old Dominion University

Frustrated Drift Of An Anchored Scroll-Wave Filament And The Geodesic Principle, Marcel Wellner, Christian W. Zemlin, Arkady M. Pertsov

Bioelectrics Publications

We investigate anchored scroll-wave filaments in an excitable medium whose diffusivity matrix, including its determinant, is spatially nonuniform. The study is motivated by cardiological applications where scroll-wave behavior in the presence of diffusivity gradients is believed to play an important role in the development of severe arrhythmias. A diffusivity gradient is expected to make the filament drift, unless drift is prevented ("frustrated") by anchoring to localized defects in the propagation medium. The resulting stationary filament is a geodesic curve, as demonstrated here in the case of a nonzero but constant gradient. That is, the diffusivity matrix has a determinant that ...


Electroporation-Mediated Delivery Of A Naked Dna Plasmid Expressing Vegf To The Porcine Heart Enhances Protein Expression, W. G. Marshall Jr., B. A. Boone, J. D. Burgos, S. I. Gografe, M. K. Baldwin, M. L. Danielson, M. J. Larson, D. R. Caretto, Y. Cruz, B. Ferraro, L. C. Heller, K. E. Ugen, M. J. Jaroszeski, R. Heller 2010 Old Dominion University

Electroporation-Mediated Delivery Of A Naked Dna Plasmid Expressing Vegf To The Porcine Heart Enhances Protein Expression, W. G. Marshall Jr., B. A. Boone, J. D. Burgos, S. I. Gografe, M. K. Baldwin, M. L. Danielson, M. J. Larson, D. R. Caretto, Y. Cruz, B. Ferraro, L. C. Heller, K. E. Ugen, M. J. Jaroszeski, R. Heller

Bioelectrics Publications

Gene therapy is an attractive method for the treatment of cardiovascular disease. However, using current strategies, induction of gene expression at therapeutic levels is often inefficient. In this study, we show a novel electroporation (EP) method to enhance the delivery of a plasmid expressing an angiogenic growth factor (vascular endothelial growth factor, VEGF), which is a molecule previously documented to stimulate revascularization in coronary artery disease. DNA expression plasmids were delivered in vivo to the porcine heart with or without coadministered EP to determine the potential effect of electrically mediated delivery. The results showed that plasmid delivery through EP significantly ...


Electronic Falls Reporting System Implementation: Evaluating Data Collection Methods And Studying User Acceptance, Yi You Mei 2010 University of Massachusetts Amherst

Electronic Falls Reporting System Implementation: Evaluating Data Collection Methods And Studying User Acceptance, Yi You Mei

Masters Theses 1911 - February 2014

In this research, we detail the development of a novel, easy-to-use system to facilitate electronic patient falls reporting within a long-term residential care facility (LTRCF) using off-the-shelf technology that can be inexpensively implemented in a wide variety of settings. We report the results of four complimentary system evaluation measures that take into consideration varied organizational stakeholders’ perspectives: 1) System-level benefits and costs, 2) System usability, via scenario-based use cases, 3) A holistic assessment of users’ physical, cognitive, and marcoergonomic (work system) challenges in using the system, and 4) User technology acceptance. We report the viability of collecting and analyzing data ...


Terahertz And Microwave Detection Using Metallic Single Wall Carbon Nanotubes, Enrique A. Carrion 2010 University of Massachusetts Amherst

Terahertz And Microwave Detection Using Metallic Single Wall Carbon Nanotubes, Enrique A. Carrion

Masters Theses 1911 - February 2014

Carbon nanotubes (CNTs) are promising nanomaterials for high frequency applications due to their unique physical characteristics. CNTs have a low heat capacity, low intrinsic capacitance, and incredibly fast thermal time constants. They can also exhibit ballistic transport at low bias, for both phonons and electrons, as evident by their fairly long mean free paths. However, despite the great potential they present, the RF behavior of these nanostructures is not completely understood. In order to explore this high frequency regime we studied the microwave (MW) and terahertz (THz) response of individual and bundled single wall nanotube based devices. This thesis is ...


Data Fusion For The Problem Of Protein Sidechain Assignment, Yang Lei 2010 University of Massachusetts Amherst

Data Fusion For The Problem Of Protein Sidechain Assignment, Yang Lei

Masters Theses 1911 - February 2014

In this thesis, we study the problem of protein side chain assignment (SCA) given

multiple sources of experimental and modeling data. In particular, the mechanism

of X-ray crystallography (X-ray) is re-examined using Fourier analysis, and a novel

probabilistic model of X-ray is proposed for SCA's decision making. The relationship

between the measurements in X-ray and the desired structure is reformulated in terms

of Discrete Fourier Transform (DFT). The decision making is performed by developing

a new resolution-dependent electron density map (EDM) model and applying

Maximum Likelihood (ML) estimation, which simply reduces to the Least Squares

(LS) solution. Calculation of ...


Route Choice Behavior In A Driving Simulator With Real-Time Information, Hengliang Tian 2010 University of Massachusetts Amherst

Route Choice Behavior In A Driving Simulator With Real-Time Information, Hengliang Tian

Masters Theses 1911 - February 2014

This research studies travelers' route choice behavior in a driving simulator with real-time information en-route. We investigate whether travelers plan strategically for real-time information en-route or simply select a fixed path from origin to destination at the beginning of a trip, and whether network complexity and a parallel driving task affect subjects' strategic thinking ability. In this study, strategic thinking refers to a traveler's route choice decision taking into account future diversion possibilities downstream enabled by information at the diversion node. All of the subjects in this study participated in driving-simulator-based tests while half of the subjects participated in ...


Earthquake Engineering Simulation With Flexible Cladding System, Jun Jie Li 2010 University of Massachusetts Amherst

Earthquake Engineering Simulation With Flexible Cladding System, Jun Jie Li

Masters Theses 1911 - February 2014

This research investigates the interaction between heavy precast cladding units attached to steel framed buildings. Cladding systems are designed as non-structural components and are not expected to contribute to the energy absorption of the primary structure. However, research has indicated that the cladding system may be designed to reduce the response of the primary structure under seismic excitations. The use of flexible connections between the cladding and primary structural frames may be able to provide beneficial effects to the entire structural response. In this study, a series of earthquake engineering simulations were conducted in OPENSEES to analyze the effects of ...


Comparison Of The Iowa State University Effluent Limitation Guidelines Model With The Soil-Plant-Air-Water Model For Evaluating Containment Basin Performance, Daniel S. Andersen, Robert T. Burns, Lara B. Moody, Matthew J. Helmers, Robert Horton Jr. 2010 Iowa State University

Comparison Of The Iowa State University Effluent Limitation Guidelines Model With The Soil-Plant-Air-Water Model For Evaluating Containment Basin Performance, Daniel S. Andersen, Robert T. Burns, Lara B. Moody, Matthew J. Helmers, Robert Horton Jr.

Agricultural and Biosystems Engineering Publications

This article compares results from the Iowa State University Effluent Limitations Guidelines (ISU-ELG) model to results obtained using the Soil-Plant-Air-Water (SPAW) model to simulate feedlot runoff containment basin overflow volume. The objective was to verify that the ISU-ELG model was providing a reasonable prediction of basin overflow. The ISU-ELG model uses a set of guidelines to determine if land application is acceptable, whereas the SPAW model uses a soil moisture criterion. The criterion for determining if a particular day was suitable for land application of basin effluent was investigated to determine the effect on basin overflow volumes. The results show ...


Effect Of Ammonia Soaking Pretreatment And Enzyme Addition On Biochemical Methane Potential Of Switchgrass, Jennifer Nicole Himmelsbach, D. Raj Raman, Robert P. Anex, Robert T. Burns, Carol Rose Faulhaber 2010 Iowa State University

Effect Of Ammonia Soaking Pretreatment And Enzyme Addition On Biochemical Methane Potential Of Switchgrass, Jennifer Nicole Himmelsbach, D. Raj Raman, Robert P. Anex, Robert T. Burns, Carol Rose Faulhaber

Agricultural and Biosystems Engineering Publications

This article presents the biochemical methane potential (BMP) results from the anaerobic digestion (AD) of switchgrass. Triplicate BMP assays were performed on: untreated switchgrass, aqueous ammonia soaking (AAS) pretreated switchgrass (soaked in 29.5% reagent-grade aqueous ammonia at 5 L kg-1 switchgrass for 5 d), and AAS-pretreated switchgrass plus cellulytic enzymes at 12.5, 25, 62.5, and 125 filter paper units (FPU) enzyme g-1 volatile solids (VS). Biogas production and biogas methane content were measured daily in all treatments for 21 d. Both biogas and corrected methane production varied significantly among treatments, especially during the first 7 d of ...


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