WorldWideScience

Sample records for electrochemical rutherford backscattering

  1. Monolayer resolution in Rutherford backscattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, K. [Kyoto Univ. (Japan). Dept. of Engineering Science; Ohshima, K. [Kyoto Univ. (Japan). Dept. of Engineering Science; Nakajima, K. [Kyoto Univ. (Japan). Dept. of Engineering Science; Fujii, Y. [Kyoto Univ. (Japan). Dept. of Engineering Science; Mannami, M. [Kyoto Univ. (Japan). Dept. of Engineering Science; Gossmann, H.J. [AT and T Bell Laboratories, Murray Hill, NJ 07974 (United States)

    1995-05-01

    Conditions for to obtain monolayer resolution in Rutherford backscattering spectroscopy are discussed. It is shown that both high energy resolution and the grazing angle technique are essential to achieve monolayer resolution. A 90 sector magnetic spectrometer ({delta}E/E similar 0.1%) is utilized for high-resolution Rutherford backscattering spectroscopy (HRBS). Energy spectra of scattered 300-keV He ions from single crystals are measured with the spectrometer at grazing exit angles. The ions scattered from successive atomic layers can be resolved as separated peaks in the energy spectra. Results of some applications of HRBS are presented. (orig.).

  2. Improvement of sensitivity in high-resolution Rutherford backscattering spectroscopy.

    Science.gov (United States)

    Hashimoto, H; Nakajima, K; Suzuki, M; Sasakawa, K; Kimura, K

    2011-06-01

    The sensitivity (limit of detection) of high-resolution Rutherford backscattering spectroscopy (HRBS) is mainly determined by the background noise of the spectrometer. There are two major origins of the background noise in HRBS, one is the stray ions scattered from the inner wall of the vacuum chamber of the spectrometer and the other is the dark noise of the microchannel plate (MCP) detector which is commonly used as a focal plane detector of the spectrometer in HRBS. In order to reject the stray ions, several barriers are installed inside the spectrometer and a thin Mylar foil is mounted in front of the detector. The dark noise of the MCP detector is rejected by the coincidence measurement with the secondary electrons emitted from the Mylar foil upon the ion passage. After these improvements, the background noise is reduced by a factor of 200 at a maximum. The detection limit can be improved down to 10 ppm for As in Si at a measurement time of 1 h under ideal conditions. © 2011 American Institute of Physics

  3. A didactic proposal about Rutherford backscattering spectrometry with theoretic, experimental, simulation and application activities

    Science.gov (United States)

    Corni, Federico; Michelini, Marisa

    2018-01-01

    Rutherford backscattering spectrometry is a nuclear analysis technique widely used for materials science investigation. Despite the strict technical requirements to perform the data acquisition, the interpretation of a spectrum is within the reach of general physics students. The main phenomena occurring during a collision between helium ions—with energy of a few MeV—and matter are: elastic nuclear collision, elastic scattering, and, in the case of non-surface collision, ion stopping. To interpret these phenomena, we use classical physics models: material point elastic collision, unscreened Coulomb scattering, and inelastic energy loss of ions with electrons, respectively. We present the educational proposal for Rutherford backscattering spectrometry, within the framework of the model of educational reconstruction, following a rationale that links basic physics concepts with quantities for spectra analysis. This contribution offers the opportunity to design didactic specific interventions suitable for undergraduate and secondary school students.

  4. Accurate determination of quantity of material in thin films by Rutherford backscattering spectrometry.

    Science.gov (United States)

    Jeynes, C; Barradas, N P; Szilágyi, E

    2012-07-17

    Ion beam analysis (IBA) is a cluster of techniques including Rutherford and non-Rutherford backscattering spectrometry and particle-induced X-ray emission (PIXE). Recently, the ability to treat multiple IBA techniques (including PIXE) self-consistently has been demonstrated. The utility of IBA for accurately depth profiling thin films is critically reviewed. As an important example of IBA, three laboratories have independently measured a silicon sample implanted with a fluence of nominally 5 × 10(15) As/cm(2) at an unprecedented absolute accuracy. Using 1.5 MeV (4)He(+) Rutherford backscattering spectrometry (RBS), each lab has demonstrated a combined standard uncertainty around 1% (coverage factor k = 1) traceable to an Sb-implanted certified reference material through the silicon electronic stopping power. The uncertainty budget shows that this accuracy is dominated by the knowledge of the electronic stopping, but that special care must also be taken to accurately determine the electronic gain of the detection system and other parameters. This RBS method is quite general and can be used routinely to accurately validate ion implanter charge collection systems, to certify SIMS standards, and for other applications. The generality of application of such methods in IBA is emphasized: if RBS and PIXE data are analysed self-consistently then the resulting depth profile inherits the accuracy and depth resolution of RBS and the sensitivity and elemental discrimination of PIXE.

  5. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaodong, E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Hayward, Jason P. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Oak Ridge National Lab, Oak Ridge, TN 37831 (United States)

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick’s second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  6. Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

    Science.gov (United States)

    Chawla, Mahak; Aggarwal, Sanjeev; Sharma, Annu

    2017-09-01

    The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100 keV N+ ions at different fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm-2 with beam current density of ∼0.65 μA cm-2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV-Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33 at.% (virgin) to 42 at.% at fluence of 1 × 1017 N+ cm-2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV-Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12 eV (virgin) to 0.25 eV (1 × 1017 N+ cm-2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV-Visible have been further correlated with the outcomes of the RBS characterization.

  7. Profiling measurements of metal ion distribution in thin polymer inclusion membranes by Rutherford backscattering spectrometry

    Science.gov (United States)

    Guedioura, B.; Bendjaballah, N.; Alioui, N.

    2014-05-01

    Polymer inclusion membranes (PIMs) composed of a homogeneous mixture of cellulose triacetate matrix, 2-nitro-phenyl-octyl-ether as plasticizer and tri-octyl-phosphine-oxyde as carrier were synthesized by the spin coating method. Synthesized membranes were doped with molybdenum metal ions and then characterized by four experimental techniques: thermo gravimetric and differential analyses, scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and Rutherford backscattering (RBS) spectrometry using a 3.2 MeV He+ ion beam. The RBS analysis has established both the elemental composition as well as the Mo+ metal profiling of the studied PIMs. The experimental irradiation conditions were optimized in order to determine the ion fluence thresholds resulting in measurable changes in elemental composition of membranes. Changes in physico-chemical properties of the irradiated PIMs vs He+ ion fluence were observed with the ATR-FTIR analysis. Also, the SEM analysis of PIMs surfaces has revealed a porous texture, while the thermal analysis of annealed PIMs at 105°C has showed no significant changes of mass (∼1%) of the studied samples.

  8. Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Tomoaki, E-mail: t-nishi@hosei.ac.jp

    2016-03-15

    A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of {sup 16}O({sup 4}He, {sup 4}He){sup 16}O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

  9. Characterization of gold nanoparticle films: Rutherford backscattering spectroscopy, scanning electron microscopy with image analysis, and atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Pia C. Lansåker

    2014-10-01

    Full Text Available Gold nanoparticle films are of interest in several branches of science and technology, and accurate sample characterization is needed but technically demanding. We prepared such films by DC magnetron sputtering and recorded their mass thickness by Rutherford backscattering spectroscopy. The geometric thickness dg—from the substrate to the tops of the nanoparticles—was obtained by scanning electron microscopy (SEM combined with image analysis as well as by atomic force microscopy (AFM. The various techniques yielded an internally consistent characterization of the films. In particular, very similar results for dg were obtained by SEM with image analysis and by AFM.

  10. Fe-implanted SiC as a potential DMS: X-ray diffraction and rutherford backscattering and channelling study

    Energy Technology Data Exchange (ETDEWEB)

    Dupeyrat, C., E-mail: cyril.dupeyrat@etu.univ-poitiers.f [Laboratoire de Physique des Materiaux (PhyMat), SP2MI, teleport 2, Bvd M. et P. Curie, 86962 Chasseneuil-Futuroscope (France); Declemy, A.; Drouet, M. [Laboratoire de Physique des Materiaux (PhyMat), SP2MI, teleport 2, Bvd M. et P. Curie, 86962 Chasseneuil-Futuroscope (France); Debelle, A.; Thome, L. [Centre de Spectrometrie Nucleaire et Spectrometrie de Masse (CSNSM), Universite Paris-Sud 11, Bat 104, 91405 Orsay (France)

    2010-10-01

    Single crystalline (0 0 0 1)-oriented 6H-SiC samples were implanted at 380 {sup o}C with low-energy Fe ions (in the 100 keV range) with the aim of synthesizing so-called diluted magnetic semiconductors. X-ray diffraction and Rutherford backscattering spectrometry and channeling are used to study the microstructural changes in these Fe-implanted SiC crystals submitted to furnace annealing and laser processing, both treatments being performed in order to eliminate the implantation-induced defects.

  11. In-air Rutherford Backscattering and Particle Induced X-ray Emission for Biophysics and Material Science Research

    Science.gov (United States)

    Becker, James

    2015-03-01

    Rutherford Backscattering (RBS) and Particle Induced X-ray Emission (PIXE) are methods of nondestructive analysis of elemental composition. Rebounding particles or emitted x-rays can be ``collected'' and then analyzed to reveal the number ratio of the elements in a sample. Due to the nondestructive feature of these processes, RBS and PIXE are useful in many diverse fields of study such as archaeology, art, and biology; however, these experiments usually require large, expensive particle accelerators and detectors. Instead, I am attempting to use a radioactive source, photodiodes, and computer software to perform the same methods at a fraction of the cost. I am exploring cost, time, and resolution benefits and losses of my approach versus the traditional accelerator-based approach.

  12. Interaction of europium and nickel with calcite studied by Rutherford Backscattering Spectrometry and Time-Resolved Laser Fluorescence Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, A. [Agence Nationale pour la gestion des Déchets RAdioactifs, 1-7 rue J. Monnet, Parc de la Croix Blanche, 92298 Châtenay-Malabry Cedex (France); Université de Nice Sophia Antipolis, Ecosystèmes Côtiers Marins et Réponses aux Stress (ECOMERS), 28 avenue Valrose, 06108 Nice Cedex 2 (France); Pipon, Y., E-mail: pipon@ipnl.in2p3.fr [Institut de Physique Nucléaire de Lyon (IPNL), Université Lyon 1, CNRS/IN2P3, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); Institut Universitaire de Technologie (IUT) Lyon-1, Université Claude Bernard Lyon 1, 69 622 Villeurbanne Cedex (France); Toulhoat, N. [Institut de Physique Nucléaire de Lyon (IPNL), Université Lyon 1, CNRS/IN2P3, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); CEA/DEN, Saclay, 91191 Gif sur Yvette (France); Lomenech, C. [Université de Nice Sophia Antipolis, Ecosystèmes Côtiers Marins et Réponses aux Stress (ECOMERS), 28 avenue Valrose, 06108 Nice Cedex 2 (France); Jordan, N. [Helmholtz Zentrum Dresden Rossendorf (HZDR), Institute of Resource Ecology (IRE) (Germany); Moncoffre, N. [Institut de Physique Nucléaire de Lyon (IPNL), Université Lyon 1, CNRS/IN2P3, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); Barkleit, A. [Helmholtz Zentrum Dresden Rossendorf (HZDR), Institute of Resource Ecology (IRE) (Germany); and others

    2014-08-01

    This study aims at elucidating the mechanisms regulating the interaction of Eu and Ni with calcite (CaCO{sub 3}). Calcite powders or single crystals (some mm sized) were put into contact with Eu or Ni solutions at concentrations ranging from 10{sup −3} to 10{sup −5} mol L{sup −1} for Eu and 10{sup −3} mol L{sup −1} for Ni. The sorption durations ranged from 1 week to 1 month. Rutherford Backscattering Spectrometry (RBS) well adapted to discriminate incorporation processes such as: (i) adsorption or co precipitation at the mineral surfaces or, (ii) incorporation into the mineral structure (through diffusion for instance), has been carried out. Moreover, using the fluorescence properties of europium, the results have been compared to those obtained by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) on calcite powders. For the single crystals, complementary SEM observations of the mineral surfaces at low voltage were also performed. Results showed that Ni accumulates at the calcite surface whereas Eu is also incorporated at a greater depth. Eu seems therefore to be incorporated into two different states in calcite: (i) heterogeneous surface accumulation and (ii) incorporation at depth greater than 160 nm after 1 month of sorption. Ni was found to accumulate at the surface of calcite without incorporation.

  13. Selective Rutherford backscattering techniques in the study of transition-metal implanted YBa{sub 2}C{sub 3}O{sub 7-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J.W.; Russell, G.J. [New South Wales Univ., Kensington, NSW (Australia). School of Physics; Cohen, D.D.; Evans, P.J. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1993-12-31

    Using a metal-vapor vacuum arc ion source, several as-grown, large single crystal YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were implanted with a dose of 1x10{sup 17} zinc, nickel and iron ions. After implantation the crystal was subjected to two anneal cycles that has allowed to examine crystal structure, superconducting transitions and composition, through X-ray diffraction, rutherford backscattering spectroscopy (RBS) and AC susceptibility measurements respectively. Although RBS discriminates strongly against light elements, such as oxygen, the use of resonant reaction {sup 16}O ({alpha}, {alpha}){sup 16}O at 3.4 MeV was beneficial, as its cross section is nearly 23 times that of the rutherford cross section. 4 figs.

  14. Dislocation and Elastic Strain in an InN Film Characterized by Synchrotron Radiation X-Ray Diffraction and Rutherford Backscattering/Channeling

    Science.gov (United States)

    Cheng, Feng-Feng; Fa, Tao; Wang, Xin-Qiang; Yao, Shu-De

    2012-02-01

    Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-μm-thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD). The minimum yield χmin = 2.5% deduced from the RBS/C results indicates a fairly good crystalline quality. From the SR-XRD results, we obtain the values of the screw and edge densities to be ρscrew = 7.0027 × 109 and ρedge = 8.6115 × 109 cm-2, respectively. The tetragonal distortion of the sample is found to be -0.27% by angular scans, which is close to the -0.28% derived by SR-XRD. The value of |e⊥/e∥| = 0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis, where e∥ is the parallel elastic strain, and e⊥ is the perpendicular elastic strain. Photoluminescence results reveal a main peak of 0.653 eV with the linewidth of 60 meV, additional shoulder band could be due to impurities and related defects.

  15. Rutherford Backscattering Spectrometry Analysis and Structural Properties of ZnxPb1-xS Thin Films Deposited by Chemical Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Abiodun E. Adeoye

    2015-01-01

    Full Text Available Zinc lead sulphide ternary thin films were prepared by chemical spray pyrolysis on soda lime glass substrates using zinc acetate, lead acetate, and thiourea sources precursor. The films were characterized using Rutherford backscattering (RBS spectrometry, energy dispersive X-ray (EDX spectroscopy, scanning electron microscopy (SEM, and X-ray diffractometry (XRD. RBS studies revealed variation in thickness and stoichiometry of the films with respect to compositional substitution between Zn and Pb, thereby giving effective composition ZnxPb1-xS, where x=0, 0.035, 0.069, 0.109, 0.176, and 0.217. Film thickness obtained by length conversion ranged from 81.02 nm to 90.03 nm. Microstructural analyses also indicated that the growth and particle distribution of the films were uniform across substrate’s surface. Diffraction studies showed that the films possess FCC crystalline structure. Crystallite size reduced from 14.28 to 9.8 nm with increase in Zn2+ in the ZnxPb1-xS samples.

  16. A high-resolution electrostatic spectrometer for the investigation of near-surface layers in solids by high-resolution Rutherford backscattering with MeV ions

    Science.gov (United States)

    Enders, Th.; Rilli, M.; Carstanjen, H. D.

    1992-02-01

    The paper reports on a high-resolution electrostatic spectrometer for MeV ions and its use for investigating surfaces and near-surface layers of solids by high-resolution Rutherford backscattering spectroscopy (HRBS). The spectrometer has been set up at the 6 MV Pelletron accelerator of the Max-Planck-Institut für Metallforschung, Stuttgart, over the last few years and has recently been operated successfully. The instrument consists of a cylinder type, 100° electrostatic analyzer (radius: 700 mm, gap width: 20 mm) and a system of electrostatic quadrupole lenses which focus those ions emitted from the target parallel to the optical axis onto the entrance slit of the analyzer, thus minimizing kinematic errors in the energy resolution. A variable slit system allows one to choose between a maximum in energy resolution or in ion count rate. The analyzed ions are registered simultaneously with a position sensitive Si-surface barrier detector. The maximum ion energy to be analyzed is about 2 MeV for singly charged ions. The relative energy resolution of the instrument is better than 3 × 10 -4. The overall resolution as obtained in an actual HRBS measurement with 1 MeV 4He + ions amounts to 1.44 keV, thus providing a depth resolution of 0.88 nm at ion incidence of 22.5° to the surface normal or 0.17 nm for oblique incidence of the ion beam (10° to the normal) in Au. Besides the description of the spectrometer and its capabilities, this paper will give examples of various applications. They include studies of the oxidation of metal surfaces, of island formation on surfaces, and of electron capture processes of fast ions in the near surface region.

  17. Deviations from Vegard's law in semiconductor thin films measured with X-ray diffraction and Rutherford backscattering: The Ge1-ySny and Ge1-xSix cases

    Science.gov (United States)

    Xu, Chi; Senaratne, Charutha L.; Culbertson, Robert J.; Kouvetakis, John; Menéndez, José

    2017-09-01

    The compositional dependence of the lattice parameter in Ge1-ySny alloys has been determined from combined X-ray diffraction and Rutherford Backscattering (RBS) measurements of a large set of epitaxial films with compositions in the 0 zero within experimental error, so that the system follows Vegard's law. This is in qualitative agreement with ab initio theory, but the value of the experimental bowing parameter is significantly smaller than the theoretical prediction. Possible reasons for this discrepancy are discussed in detail.

  18. Rutherford's war

    Science.gov (United States)

    Campbell, John

    2016-02-01

    Seagulls, sea lions and the comic-book hero Professor Radium were all recruited to fight the threat of submarines during the First World War. But as John Campbell explains, it was Ernest Rutherford who led the way a century ago in using acoustics to deter these deadly craft.

  19. Ernest Rutherford

    Indian Academy of Sciences (India)

    degree. At McGill, Canada. The laboratory at McGill was well equipped being generously financed by a tobacco millionaire for whom smoking was a dirty habit. Rutherford considered the laboratory to be the best of its kind in the world and resumed his work on radioactive emission. He became the world's centre of research ...

  20. Rutherford, Prof. Ernest (Lord)

    Indian Academy of Sciences (India)

    Rutherford, Prof. Ernest (Lord) Nobel Laureate (Chemistry) - 1908. Date of birth: 30 August 1871. Date of death: 19 October 1937. YouTube ... Posted on 21 December 2017. ASTROPHYSICS: An Observational View of the Universe. Math Art and Design: MAD about Math, Math Education and Outreach. Math and Finance ...

  1. Earnest Rutherford, the solution

    CERN Multimedia

    2003-01-01

    If you did not make it to the Science & Society talk by John Campbell last week and are still wondering about the spelling of "Earnest", here is the solution: Two months after the birth of his fourth child on 30 August 1871 in Spring Grove, New Zealand, James Rutherford registered his son, who was recorded as "Earnest" in the Birth Register. Presumably the Registrar wrote the name down as it sounded and the father failed to notice the mistake when signing the Register.

  2. Relative Li-ion mobility mapping in Li0.33La0.56TiO3 polycrystalline by electron backscatter diffraction and electrochemical strain microscopy

    Science.gov (United States)

    Sasano, Shun; Ishikawa, Ryo; Sugiyama, Issei; Higashi, Takuma; Kimura, Teiichi; Ikuhara, Yumi H.; Shibata, Naoya; Ikuhara, Yuichi

    2017-06-01

    Li-ion conductivity in a solid-state electrolyte has so far been measured by impedance spectroscopy. In this method, however, it is difficult to obtain microstructural information because of the absence of spatial resolution. Here, we show the relationship between the Li-ion mobility and the crystal orientation in Li0.33La0.56TiO3 polycrystalline by electrochemical strain microscopy combined with electron backscatter diffraction. On the experimentally constructed multivariable regression model, we obtained a qualitative Li-ion mobility map of sub-millimeter width with a 100 nm spatial resolution, which is impossible to achieve by only atomic force microscopy. The proposed method must be useful for identifying the Li-ion diffusion pathway in three dimensions.

  3. A brief history of Lord Rutherford's radium.

    Science.gov (United States)

    Todd, Neil

    2014-09-20

    In this paper I give a brief summary of what is known about the acquisition, use and fate of the radium sources that were in the possession of Lord Rutherford during his lifetime. The account is written in two parts, corresponding to the periods from the discovery of radium in 1898 until his death in 1937 and then from 1937 until recent times. The history of Rutherford's radium closely shadows the history of radioactivity, the evolution of nuclear physics, the race for the bomb, and the development of the nuclear industry.

  4. PREFACE: Rutherford Centennial Conference on Nuclear Physics

    Science.gov (United States)

    Freeman, Sean

    2012-09-01

    Just over one hundred years ago, Ernest Rutherford presented an interpretation of alpha-particle scattering experiments, performed a couple of years earlier by Geiger and Marsden, to the Manchester Literary and Philosophical Society. The work was summarised shortly afterwards in a paper in the Philosophical Magazine. He postulated that a dense speck of matter must exist at the centre of an atom (later to become known as the nucleus) if the details of the experiments, particularly the yield of alpha particles scattered through large angles, were to be explained. The nuclear hypothesis, combined with the experimental work by Moseley on X-rays and Bohr's theoretical ideas, both also initiated at the Victoria University of Manchester, established our view of atomic structure and gave birth to the field of nuclear physics. The Rutherford Centennial Conference on Nuclear Physics was held at The University of Manchester in August 2011 to celebrate this anniversary by addressing the wide range of contemporary topics that characterise modern nuclear physics. This set of proceedings covers areas including nuclear structure and astrophysics, hadron structure and spectroscopy, fundamental interactions studied within the nucleus and results of relativistic heavy-ion collisions. We would like to thank all those who presented their recent research results at the conference; the proceedings stand as a testament to the excitement and interest that still pervades the pursuit of this field of physics. We would also like to thank those who contributed in other ways to the conference. To colleagues at the Manchester Museum of Science and Industry for putting together an exhibition to coincide with the conference that included the manuscript of the 1911 paper, letters, notebooks and equipment used by Rutherford. These items were kindly loaned by Cambridge and Manchester Universities. Winton Capital generously supported this exhibition. We would also like to thank Professor Mary Fowler

  5. CERN celebrates the ‘Rutherford centenary’

    CERN Multimedia

    Maximilien Brice

    2011-01-01

    CERN marked the centenary of the discovery of the atomic nucleus, as published in Ernest Rutherford’s famous paper of 1911, with its Rutherford Centennial Colloquium, held on 15 November in the presence of John Adank, New Zealand’s ambassador to the World Trade Organization in Geneva. After an introduction by CERN’s director-general, Rolf Heuer, the speakers covered topics ranging from Rutherford’s early life in New Zealand, presented by his great grand-daughter Mary Fowler, through to his role as an inspiration to young scientists in his homeland, as seen by New Zealander Mark Kruse, who is now at Duke University and a member of the ATLAS collaboration. Fellow New Zealander, John Campbell, spoke about Rutherford’s road to discovery of the nuclear atom. Rutherford’s scientific legacy in nuclear physics was covered by Sean Freeman, appropriately from Manchester University, where the famous scattering experiment took place. Jerome Friedman delved deeper into matter with his talk detailing the scatt...

  6. Traffic modifications on Routes Rutherford, Democrite and Fermi

    CERN Multimedia

    2015-01-01

    The GS Department would like to inform you that until the end of December, the construction of Building 245 will result in the following traffic modifications: Traffic on Route Rutherford will be partially restricted in front of the construction site, Traffic on Route Democrite will be one-way towards Route Rutherford. Also, please note that due to construction work in front of Building 377, Route Fermi will be closed from Wednesday, 10 June until Friday, 7 August. Thank you for your understanding.

  7. Atomic Energy is "Moonshine": What did Rutherford Really Mean?

    Science.gov (United States)

    Jenkin, John G.

    2011-06-01

    In the 1930s Ernest Rutherford (1871-1937) repeatedly suggested, sometimes angrily, that the possibility of harnessing atomic energy was "moonshine." Yet, as war approached he secretly advised the British government to "keep an eye on the matter." I suggest that Rutherford did not really believe his "moonshine" claim but did have profound reasons for making it. If I am correct, then this casts additional light on his personality, stature, and career.

  8. Traffic modifications on Routes Rutherford, Democrite and Fermi

    CERN Multimedia

    2015-01-01

    The GS Department would like to inform you that, until the end of December, the construction of Building 245 will result in the following traffic modifications: Traffic on Route Rutherford will be partially restricted in front of the construction site, Traffic on Route Democrite will be one-way towards Route Rutherford. Also, please note that due to construction work in front of Building 377, Route Fermi will be closed from Wednesday, 10 June until Friday, 7 August. Thank you for your understanding.

  9. Clinical characteristics of patients with Rutherford category IV, compared with V and VI

    Directory of Open Access Journals (Sweden)

    Taketsugu Tsuchiya

    2015-07-01

    Full Text Available Objective: Patients categorized Rutherford category IV might have different characteristics compared with Rutherford category V and VI. Our study aims were to estimate the clinical differences between Rutherford category IV and Rutherford category V and VI, for those underwent endovascular therapy for isolated infrapopliteal disease, and also to find risk factors for endovascular therapy in Rutherford category IV. Methods: Based on the Japanese multi-center registry data, 1091 patients with 1332 limbs (Rutherford category IV: 226 patients with 315 limbs, Rutherford category V and VI: 865 patients with 1017 limbs were analyzed retrospectively. Results: Patients’ backgrounds and lesions’ characteristics had significant differences. Both freedom rate from major adverse limb event with perioperative death and amputation-free survival rate at 1 year were better in Rutherford category IV than Rutherford category V and VI (93.6% vs 78.3%, 87.7% vs 66.7% and those maintained to 3 years (p  3.0 mg/dL, chronic obstructive pulmonary disease, and coronary artery disease in Rutherford category IV. Conclusion: From the present results, Rutherford category IV should be recognized to have quite different backgrounds and better outcome from Rutherford category V and VI.

  10. Stability of Superconducting Rutherford Cables For accelerator magnets

    CERN Document Server

    Willering, GP; Verweij, A P

    2009-01-01

    The stability of superconducting magnets has a high priority for particle accelerators, since the operational time and operational collision energy depend strongly on it. Local heat dissipation due to beam loss and conductor movement is inevitable, causing local hot spots in the conductor, possibly leading to magnet quench. For stability against local and transient energy deposition, the cable is the most important unit to investigate. Most superconducting accelerator magnets are wound from Rutherford cables with a flat cable layout, consisting of twisted strands. The mechanisms of normal zone propagation in Rutherford cables have been described in detail with experimental and modeling data. The onset of a local normal zone forces current to redistribute in adjacent neighboring superconducting strands, reducing the longitudinal normal zone propagation. Transversal normal zone propagation in adjacent and crossing strands is caused by the redistribution of current and by heat exchange. The mechanism of normal z...

  11. Science & Society: The search for the real Earnest Rutherford*

    CERN Multimedia

    2003-01-01

    Every physicist knows the name Rutherford who radically altered our understanding of nature on three separate occasions. Through brilliantly conceived experiments, and with special insight, he explained the perplexing problem of radioactivity as the spontaneous disintegration of atoms (they were not necessarily stable entities as had been assumed since the time of the ancient Greeks), he determined the structure of the atom and he was the world's first successful alchemist (he converted nitrogen into oxygen). This talk given by John Campbell, however, will cover some of the lesser known aspects of Rutherford's work, including his early wireless signalling, development of what was later improved to be now called the Geiger-Muller tube, his acoustic work for submarine detection during the First World War, the development of particle accelerators and the race to use them, the first use of a coincidence detector, and why he received just one Nobel Prize. Dr Campbell, a condensed matter physicist at the Universi...

  12. The collected papers of Lord Rutherford of Nelson

    CERN Document Server

    Rutherford, Ernest

    1962-01-01

    This is the third of three volumes which together contain the complete range of Lord Rutherford's scientific papers, incorporating in addition addresses, general lectures, letters to editors, accounts of his scientific work and personal recollections by friends and colleagues. The final volume, first published in 1965, covers his period as Cavendish Professor from 1919 to 1937. Following on the immense fertility of his years in Manchester - only overshadowed towards the end by the war - we now turn to his last years as a world figure at the Cavendish Laboratory, where he continued his work on

  13. Experimenting from a distance in the case of Rutherford scattering

    Energy Technology Data Exchange (ETDEWEB)

    Groeber, S; Vetter, M; Eckert, B; Jodl, H-J, E-mail: groeber@rhrk.uni-kl.d [Department of Physics, University of Technology Kaiserslautern, Erwin-Schroedinger-Strasse, 67663 Kaiserslautern (Germany)

    2010-07-15

    The Rutherford scattering experiment plays a central role in working out atomic models in physics and chemistry. Nevertheless, the experiment is rarely performed at school or in introductory physics courses at university. Therefore, we realized this experiment as a remotely controlled laboratory (RCL), i.e. the experiment is set up in reality and can be operated by a computer via the Internet. We present results of measurements and supplementary didactical material. In addition, we make suggestions on how to use the RCL in class and we describe the added value of performing this experiment as an RCL.

  14. Strand critical current degradation in $Nb_{3}$ Sn Rutherford cables

    CERN Document Server

    Barzi, E; Higley, H C; Scanlan, R M; Yamada, R; Zlobin, A V

    2001-01-01

    Fermilab is developing 11 Tesla superconducting accelerator magnets based on Nb/sub 3/Sn superconductor. Multifilamentary Nb/sub 3/Sn strands produced using the modified jelly roll, internal tin, and powder-in-tube technologies were used for the development and test of the prototype cable. To optimize the cable geometry with respect to the critical current, short samples of Rutherford cable with packing factors in the 85 to 95% range were fabricated and studied. In this paper, the results of measurements of critical current, n-value and RRR made on the round virgin strands and on the strands extracted from the cable samples are presented. (5 refs).

  15. Stability Measurements of Rutherford Cables with Various Treatments

    CERN Document Server

    Kim, S W; Wilson, M N; Ghosh, A; Sampson, W B

    1999-01-01

    To improve the stability of Rutherford type superconducting cables, various methods of treating cables were considered and tested. These treatments include strand coating, partial soldering, "barber-pole" insulation and "porous $9 metal" solder filling. To study the effect of these treatments, several cables were prepared and MQE (minimum quench energy) values were measured. Coating, partial soldering or "barber-pole insulation" improved the relative stability $9 for some cables. The "porous metal" filled cables showed higher MQE. However the results suggest that the porous metal process needs to be improved. The measured data for cables with various treatments are presented. (8 refs).

  16. Nonlinear Plasma Response to Resonant Magnetic Perturbation in Rutherford Regime

    Science.gov (United States)

    Zhu, Ping; Yan, Xingting; Huang, Wenlong

    2017-10-01

    Recently a common analytic relation for both the locked mode and the nonlinear plasma response in the Rutherford regime has been developed based on the steady-state solution to the coupled dynamic system of magnetic island evolution and torque balance equations. The analytic relation predicts the threshold and the island size for the full penetration of resonant magnetic perturbation (RMP). It also rigorously proves a screening effect of the equilibrium toroidal flow. In this work, we test the theory by solving for the nonlinear plasma response to a single-helicity RMP of a circular-shaped limiter tokamak equilibrium with a constant toroidal flow, using the initial-value, full MHD simulation code NIMROD. Time evolution of the parallel flow or ``slip frequency'' profile and its asymptotic approach to steady state obtained from the NIMROD simulations qualitatively agree with the theory predictions. Further comparisons are carried out for the saturated island size, the threshold for full mode penetration, as well as the screening effects of equilibrium toroidal flow in order to understand the physics of nonlinear plasma response in the Rutherford regime. Supported by National Magnetic Confinement Fusion Science Program of China Grants 2014GB124002 and 2015GB101004, the 100 Talent Program of the Chinese Academy of Sciences, and U.S. Department of Energy Grants DE-FG02-86ER53218 and DE-FC02-08ER54975.

  17. Backscatter imagery in Jobos Bay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 1x1 meter resolution backscatter mosaic of Jobos Bay, Puerto Rico (in NAD83 UTM 19 North). The backscatter values are in relative 8-bit (0 –...

  18. Collective stimulated Brillouin backscatter

    CERN Document Server

    Lushnikov, Pavel M

    2007-01-01

    We develop the statistical theory of the stimulated Brillouin backscatter (BSBS) instability of a spatially and temporally partially incoherent laser beam for laser fusion relevant plasma. We find a new regime of BSBS which has a much larger threshold than the classical threshold of a coherent beam in long-scale-length laser fusion plasma. Instability is collective because it does not depend on the dynamics of isolated speckles of laser intensity, but rather depends on averaged beam intensity. We identify convective and absolute instability regimes. Well above the incoherent threshold the coherent instability growth rate is recovered. The threshold of convective instability is inside the typical parameter region of National Ignition Facility (NIF) designs although current NIF bandwidth is not large enough to insure dominance of collective instability and suggests lower instability threshold due to speckle contribution. In contrast, we estimate that the bandwidth of KrF-laser-based fusion systems would be larg...

  19. Study of oxidized iron thin films by non-Rutherford elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Villacorta, F. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)]. E-mail: felixjv@icmm.csic.es; Munoz-Martin, A. [Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

    2006-08-15

    Rutherford and non-Rutherford elastic scattering analyses have been performed to characterize oxidized iron thin films grown by sputtering. The oxygen depth profiles along the thickness of all the samples have been studied in order to unravel the oxidation process of these samples. The oxygen concentration along the film was related to the sample preparation parameters, resulting in a strong dependence of oxygen depth profile on the substrate temperature during deposition.

  20. Acoustic backscatter from turbulent microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Seim, H.E.; Gregg, M.C.; Miyamoto, R.T. [Univ. of Washington, Seattle, WA (United States)

    1995-04-01

    Acoustic backscatter has produced spectacular images of internal ocean processes for nearly two decades, but interpretation of the images remains ambiguous because several mechanisms can generate measurable backscatter. The authors present what is thought to be the first simultaneous measurements of calibrated acoustic returns and turbulent microstructure, collected in a set of 20-m-tall billows. The observations are from Admiralty Inlet, a salt-stratified tidal channel near Puget Sound. Scattering due to turbulent microstructure alone is strong enough to explain the measured backscatter at specific sites within the billows. Existing formulations underestimate the strength of acoustic backscatter from turbulent microstructure. Due to a misinterpretation of the high-wavenumber temperature spectrum, some previous formulations underestimate the differential scattering cross section (sigma) when scattering from the viscous-convective subrange. Also, the influence of salinity on refractive-index fluctuations can be as large as or greater than that of temperature when the density stratification is dominated by salinity. Using temperature alone to estimate sigma in coastal and estuarine waters may lead to significant underestimates. A simple formulation is derived that takes these two factors into account. Because of high ambient scattering from zooplankton in Admiralty Inlet, the acoustic data are conditionally sampled along modeled profiler trajectories to avoid using bulk statistics.

  1. ELECTROCHEMICAL PROPERTIES AND ELECTROCHEMICAL ...

    African Journals Online (AJOL)

    b Department of Materials Engineering and Industrial Technologies, University of Trento, 38050. Trento ... KEY WORDS: Conducting polymers, Polypyrrole, Electrochemical impedance spectroscopy, Equivalent- electrical ..... composed of a constant-phase element with exponent values of 0.38-0.67 for PPy/ClO4. -/w and.

  2. Backscatter D [Snippets]--Offshore Bolinas, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bolinas map area, California. Backscatter data are provided as separate grids...

  3. BackscatterA [8101]--Offshore Pacifica, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pacifica map area, California. Backscatter data are provided as two separate grids...

  4. Backscatter B [8101]--Offshore Bolinas, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bolinas map area, California. Backscatter data are provided as separate grids...

  5. BackscatterB [7125]--Offshore Pacifica, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pacifica map area, California. Backscatter data are provided as two separate grids...

  6. Backscatter C [7125]--Offshore Bolinas, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bolinas map area, California. Backscatter data are provided as separate grids...

  7. Backscatter [SWATH]--Offshore Santa Cruz, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Santa Cruz map area, California. Backscatter data are provided as three separate...

  8. Backscatter E [Swath]--Offshore Bolinas, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bolinas map area, California. Backscatter data are provided as separate grids...

  9. Backscatter A [8101]--Offshore San Gregorio, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3306 presents data for the acoustic-backscatter map (see sheet 3, SIM 3306) of the Offshore of San Gregorio map area, California. Backscatter data...

  10. Backscatter [5m]--Offshore Monterey, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Monterey map area, California. Backscatter data are provided as separate grids...

  11. Backscatter B [7125]--Offshore San Gregorio, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3306 presents data for the acoustic-backscatter map (see sheet 3, SIM 3306) of the Offshore of San Gregorio map area, California. Backscatter data...

  12. Nodule bottom backscattering study using multibeam echosounder

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Raju, Y; Nair, R.R.

    A study is carried out to observe the angular dependence of backscattering strength at nodule area where grab sample and photographic data is available. Theoretical study along with the experimentally observed data shows that the backscattering...

  13. Backscatter A [8101]--Offshore Bolinas, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bolinas map area, California. Backscatter data are provided as separate grids...

  14. Backscatter measurements for NIF ignition targets (invited).

    Science.gov (United States)

    Moody, J D; Datte, P; Krauter, K; Bond, E; Michel, P A; Glenzer, S H; Divol, L; Niemann, C; Suter, L; Meezan, N; MacGowan, B J; Hibbard, R; London, R; Kilkenny, J; Wallace, R; Kline, J L; Knittel, K; Frieders, G; Golick, B; Ross, G; Widmann, K; Jackson, J; Vernon, S; Clancy, T

    2010-10-01

    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ∼15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  15. Difference in Stability Between Edge and Center in a Rutherford Cable

    NARCIS (Netherlands)

    Willering, G.P.; Verweij, A.P.; Scheuerlein, C.; den Ouden, A.; ten Kate, Herman H.J.

    Keystoned superconducting Rutherford cables are widely used in accelerator magnets like in the LHC at CERN. An essential requirement in the cable design is its stability against local heat releases in the magnet windings originating from for example, strand movement or beam loss. Beam loss is the

  16. Electrochemical properties and electrochemical impedance ...

    African Journals Online (AJOL)

    Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical ...

  17. Isotropic Chiral Objects With Zero Backscattering

    CERN Document Server

    Karilainen, Antti O

    2012-01-01

    In this paper we study electrically small chiral objects with isotropic response and zero backscattering. A bi-isotropic sphere is used as a simple example and its zero-backscattering conditions are studied. A theoretical model of an object composed of three orthogonal chiral particles made of conducting wire is presented as an analog of the zero-backscattering bi-isotropic sphere. A potential application of the object as a receiving antenna or a sensor with the ability to receive power from an arbitrary direction without backscattering is discussed.

  18. Transient stability of NbTi Rutherford cables for energy storage magnet applications

    Science.gov (United States)

    Bhunia, U.; Pradhan, J.; De, A.; Roy, A.; Khare, V. K.; Dey, M. K.; Thakur, S. K.; Saha, S.; Kanithi, H.

    2017-02-01

    Stability and quench behavior against transient perturbation expected during operation of a fast cycling energy storage magnet is an important issue for its design and safe operation. Understanding of thermal stability in terms of minimum quench energy (MQE) of a superconducting cable under specific operating scenario is of primary importance for its magnet application. Process of current redistribution from quench strand to adjacent strands depends on inductive coupling and has influence on quench development in the cable. The electrodynamic and thermal behavior of a ten-strand Rutherford-type cable for SMES program in the centre is studied numerically in the framework of discrete network modeling. Influence of several parameters such as uncertainties of inter-strand transverse and adjacent resistance, cooling conditions with liquid helium, etc. on MQE and quench behavior of Rutherford cable is discussed in this paper.

  19. Study of Transient Heat Transport Mechanisms in Superfluid Helium Cooled Rutherford-Cables

    CERN Document Server

    AUTHOR|(CDS)2100615

    The Large Hadron Collider leverages superconducting magnets to focus the particle beam or keep it in its circular track. These superconducting magnets are composed of NbTi-cables with a special insulation that allows superfluid helium to enter and cool the superconducting cable. Loss mechanisms, e.g. continuous random loss of particles escaping the collimation system heating up the magnets. Hence, a local temperature increase can occur and lead to a quench of the magnets when the superconductor warms up above the critical temperature. A detailed knowledge about the temperature increases in the superconducting cable (Rutherford type) ensures a secure operation of the LHC. A sample of the Rutherford cable has been instrumented with temperature sensors. Experiments with this sample have been performed within this study to investigate the cooling performance of the helium in the cable due to heat deposition. The experiment uses a superconducting coil, placed in a cryostat, to couple with the magnetic field loss m...

  20. submitter Optimization of Nb$_{3}$Sn Rutherford Cables Geometry for the High Luminosity LHC

    CERN Document Server

    Fleiter, Jerome; Bonasia, Angelo; Bordini, Bernardo; Richter, David

    2017-01-01

    The quadrupole and dipole magnets for the LHC High Luminosity (HL-LHC) upgrade will be based on Nb3Sn Rutherford cables that operate at 1.9 K and experience magnetic fields of up to about 12 T. An important step in the design of these magnets is the development of the high aspect ratio Nb3Sn cables to achieve the nominal field with sufficient margin. The strong plastic deformation of unreacted $Nb_3Sn$ strands during the Rutherford cabling process may induce non negligible $I_c$ and RRR degradation. In this paper, the cabling degradation is investigated as a function of the cable geometry for both PIT and RRP conductors. Based on this analysis, new baseline geometries for both 11 T and QXF magnets of HL-LHC are proposed.

  1. Analysis of Nb3Sn Rutherford cable production and strand deformations

    CERN Document Server

    Peggiani, Sonia; Beghi, Marco

    The development of cutting-edge 11-12 T superconducting magnets made from Nb3Sn technology is one of the major milestones for the upgrade of the Large Hadron Collider at CERN. The upgrade, called High Luminosity LHC Project, was planned in order to reach higher luminosity and discover new particles. Replacing the NbTi superconductor with the Nb3Sn makes it possible to reach a practical operating magnetic field limit of up to 16 T. The superconducting coils are formed by Nb3Sn Rutherford cables with a trapezoidal cross section and composed of 40 strands. Since the superconducting phase of Nb3Sn is very brittle and it is reached after a thermal cycle, the Nb3Sn Rutherford cable needs to be wound in a coil before the thermal treatment. The cabling process is a delicate step in the production of high performing cables that need different systems to control their quality. This work aims to provide practical tools to analyze the Nb3Sn Rutherford cable production and the strands deformations due to the high aspec...

  2. Ion to neutral yield ratio in near 180 deg. backscattering of keV He sup + ions from insulating targets

    CERN Document Server

    Morita, K

    2003-01-01

    The ion to neutral yield ratios in near 180 deg. backscattering of keV He sup + ions from NaCl crystals have been measured as a function of the scattering energy at the surface using the co-axial impact collision ion scattering spectroscopy-Rutherford backscattering spectroscopy combined system. It is found that the charge accumulation at the surface of non-heated target during the backscattering yield measurement completely reduces the He sup + ion yield and instead enhances the Na sup + sputtering yield when secondary electron emission is prevented by a static charging up potential at the target surface. Under the condition that secondary electrons are emitted by biasing the electrode at a potential higher than the static charging-up potential, which is placed in the front of the target, the He sup + ion yield recovers and the Na sup + sputtering yield is reduced and the ion factions increase from 0.10 to 0.15 with increasing the scattering energy at the surface, which are almost consistent with those for t...

  3. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

    The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

  4. Electrochemical Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  5. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Science.gov (United States)

    Villanueva, J. R.; Olivares, Marco

    2015-11-01

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.

  6. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Olivares, Marco [Universidad Diego Portales, Avenida Ejercito Libertador 441, Facultad de Ingenieria, Santiago (Chile)

    2015-11-15

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)

  7. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J. R., E-mail: jose.villanuevalob@uv.cl [Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso (Chile); Centro de Astrofísica de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso (Chile); Olivares, Marco, E-mail: marco.olivaresr@mail.udp.cl [Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército Libertador 441, Casilla 298–V, Santiago (Chile)

    2015-11-27

    Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.

  8. Stimulated Raman backscattering at high laser intensities

    Energy Technology Data Exchange (ETDEWEB)

    Skoric, M.M. [Vinca Inst. of Nuclear Sciences, Belgrade (Yugoslavia); Tajima, Toshiki; Sasaki, Akira; Maluckov, A.; Jovanovic, M.

    1998-03-01

    Signatures of Stimulated Raman backscattering of a short-pulse high-intensity laser interacting with an underdense plasma are discussed. We introduce a nonlinear three-wave interaction model that accounts for laser pump depletion and relativistic detuning. A mechanism is revealed based on a generic route to chaos, that predicts a progressive increase of the backscatter complexity with a growing laser intensity. Importance of kinetic effects is outlined and demonstrated in fluid-hybrid and particle simulations. As an application, we show that spectral anomalies of the backscatter, predicted by the above model, are consistent with recent sub-picosecond, high-intensity laser gas-target measurements at Livermore and elsewhere. Finally, a recently proposed scheme for generation of ultra-short, low-prepulse laser pulses by Raman backscattering in a thin foil target, is shown. (author)

  9. Backscatter enhancement in scattering from rough surfaces

    Science.gov (United States)

    Papa, Robert J.; Woodworth, Margaret B.

    1989-06-01

    Stealth technology has advanced to the point where radar target cross sections are so small there is a great need to determine mean clutter cross sections and clutter variability with great accuracy. Established clutter prediction techniques result in forward scatter values that exceed backscatter. There is some new experimental data on light scattering from rough metallic surfaces which shows there is an enhancement of backscattering in the antispecular direction under some conditions. This unusual result has been addressed by several theoretical analyses with varying success at confirmation. In this report an integral form of a physical optics representation is used to simulate the experimental conditions. For a one-dimensional surface height variation this model predicts enhanced backscatter at optical frequencies. Additional calculations for the more significant radar case of microwave frequencies and a dielectric surface again predict an increase in backscatter for large or intermediate surface slope conditions.

  10. Enhanced backscattering of optical vortex fields.

    Science.gov (United States)

    Schwartz, Chaim; Dogariu, Aristide

    2005-06-15

    The effect of an incident field with a phase screw dislocation (a so-called optical vortex) on the shape of the enhanced backscattering cone was studied theoretically and demonstrated experimentally. We show that the correlation function of the incident field acts as a filter that modifies the shape of the enhanced backscattering cone. The peak value is reduced, and its width is increased as the topological charge of the phase dislocation increases.

  11. Realization of strong backscattering homogeneous regions with known backscattering coefficient in synthetic aperture radar images

    Science.gov (United States)

    Lin, Xin; Wang, Kaizhi; Wang, Junfeng; Liu, Xingzhao

    2017-01-01

    The strong backscattering homogeneous region, i.e., a uniform region with a high and constant backscattering coefficient, is important for synthetic aperture radar (SAR) image quality assessment and SAR radiometric calibration, which, however, is difficult to realize in practice with a known backscattering coefficient. We realize a strong backscattering homogeneous region with a known backscattering coefficient in SAR images by utilizing designed metal grids. First, we propose a manmade grid-structure target and realize it with aluminum in practice, which is named the metal grid. Then, the backscattering coefficient of the designed metal grid is simulated in the computer simulation technology (CST) microwave studio and measured by a radar cross-section (RCS) measurement instrument in a microwave anechoic chamber. Both CST simulation results and RCS measurement results confirm the strong backscattering property of the designed target. In addition, by utilizing the designed target, we realize a test field consisting of several strong backscattering homogeneous regions with different sizes at Shanghai Jiao Tong University, Shanghai, China. The spaceborne experiments have been carried out by the TerraSAR-X sensor over the test field in two flight campaigns in X-band with VV polarization. Experimental results demonstrate the strong backscattering property and homogeneity of the realized regions.

  12. Aluminum strand coating for increasing the interstrand contact resistance in Rutherford type superconducting cables

    CERN Document Server

    Scheuerlein, C; Verweij, A; Bonasia, A; Oberli, L; Taborelli, M; Richter, R

    2009-01-01

    The interstrand contact resistance (Rc) in Rutherford type cables for fast cycling superconducting magnets must be sufficiently high in order to limit eddy current losses. The required value for Rc depends on the cable and magnet geometries and on the foreseen cycling rate, but is typically of the order of one mW. Such values can be reached with a dedicated strand coating or with a resistive internal cable barrier. As a possible candidate Al strand coatings have been tested. For a Rutherford type inner conductor cable of the Large Hadron Collider (LHC) made of Al coated strands Rc values higher than 500 Omega are achieved. The native Al2O3 oxide layer formed at ambient temperature in air is sufficient to reach this high contact resistance. A 6 h-200 °C oxidation heat treatment in air with 100% relative humidity further increases Rc to values above 600 μOmega . Due to the high thermal and mechanical stability of Al2O3 only a relatively moderate Rc drop of about 40 % is obtained during a 190 °C heat treatmen...

  13. Low coupling loss core-strengthened Bi 2212\\/Ag Rutherford cables

    CERN Document Server

    Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R

    1999-01-01

    In a comprehensive "vertically integrated" program multifilamentary (MF) high temperature superconducting (HTSC) Bi:2212/Ag strand was fabricated using the powder-in-tube process and heat treated in oxygen by a modified standard $9 procedure. The reaction-heat-treatment (HT) was adjusted to maximize critical current (density), I/sub c/ (J /sub c/), as measured in various magnetic fields, B. A series of Rutherford cables was designed, each of which included a $9 metallic (Nichrome-80) core for strengthening and reduction of coupling loss. Prior to cable winding a series of tests examined the possibility of strand "poisoning" by the core during HT. Small model Rutherford cables were wound, $9 and after HT were prepared for I/sub c/(B) measurement and calorimetric measurement of AC loss and hence interstrand contact resistance I/sub c/(B). It was deduced that, if in direct contact with the strand during HT, the core $9 material can degrade the I/sub c/ of the cable; but steps can be taken to eliminate this probl...

  14. Critical current measurements of High-Jc Nb3Sn Rutherford cables under Transverse Compression

    CERN Document Server

    Bordini, B; Ballarino, A; Bottura, L; Oberli, L

    2013-01-01

    For the LHC upgrade, CERN has launched a large program to develop next generation accelerator magnets based on high-Jc Nb3Sn Rutherford cables. These magnets are characterized by a magnetic field and/or an aperture significantly larger than that of current Nb-Ti LHC magnets. The increased field/aperture will require coil pre-stresses much larger than 100 MPa. Since Nb3Sn cables are extremely sensitive to strain, critical current measurements under traverse compression are essential to estimate the transport current properties of the conductor within the magnet. To this purpose CERN has developed a sample holder (to be used in the FRESCA test station) that allows testing Rutherford cables under a transverse force of up to 2 MN/m. The new holder can house cable samples up to 1.8 m long and 20 mm wide. The large transverse force is only applied over the sample high field region, which is 70 cm long and over which the FRESCA dipole magnet generates a homogeneous fields of up to 10 T. Recently the critical current...

  15. Fabrication and performance of $Nb_{3}Sn$ Rutherford-type cable with Cu added as a separate component

    CERN Document Server

    Coccoli, M; Calvi, M; Caspi, S; Chiesa, L; Hafalia, R R; Higley, H C; Dietderich, D R; Gourlay, S A; Lietzke, A F; McInturff, A D; Sabbi, G L

    2004-01-01

    From the standpoint of overall conductor cost, it is desirable to minimize the amount of Cu that is co-processed with the superconductor during strand fabrication. We are investigating several approaches for fabricating multistrand cables in which the Cu is added at the final, i.e. cabling, stage of manufacture. These include mixed strand Rutherford-type cables with pure Cu strands cabled together with superconductor strands that have a low volume fraction of Cu, Cu added as a core to a Rutherford-type cable, and Cu strip added to the surface of the cable. Results on fabrication of several alternate types of Nb3Sn cables are presented. The more promising types of mixed strand and cored cables are being evaluated in short sample and small magnet tests. These results will be presented and the performance will be compared with conventional Rutherford cables where the Cu is an integral component of the superconductor strand.

  16. Highly resolving Rutherford-scattering spectrometry for the study of ZrO{sub 2} layer growth in the beginning stage; Hochaufloesende Rutherford-Streuspektrometrie zur Untersuchung von ZrO{sub 2}-Schichtwachstum im Anfangsstadium

    Energy Technology Data Exchange (ETDEWEB)

    Vieluf, Maik

    2010-06-15

    By means of High Resolution Rutherford Backscattering Spectrometry (HR-RBS) the diffusion behaviour and layer growth of ZrO{sub 2} on SiO{sub 2} and TiN in the initial regime were investigated. The analysis of concentration profiles in ultrathin layers and interfaces was the focus of this work, made possible by the excellent depth resolution of less than 0.3 nm near the surface. For the first time a two-dimensional position sensitive semiconductor detector was implemented and characterized in the setup of the HR-RBS for the improvement of the quality of the measurement results. Furthermore, a measurement procedure was put into operation that allowed the reduction of ion induced damage. Through the optimization of the experimental conditions and the development of a program package for the support of the analyst, an efficient measurement procedure could be routinely ensured. At the time of a binary collision between the incident ion and the target element with a small impact factor, the charge state changes frequently, especially due to the abruptly decreasing ion velocity of the projectile and the overlapping of the electron clouds. For HR-RBS with an energy-separating dipole magnet, the charge state distribution of the scattered ions must be known for the interpretation of the measured spectra. For the first time a significant dependence of the charge state distribution of the scattered C ions on the layer thickness as well as atomic number of the detected target elements, here from the fourth subgroup, was demonstrated. This new knowledge allowed systematic investigations of the ZrO{sub 2} layer growth in the initial regime. The ZrO{sub 2} layers were produced by means of the atomic layer deposition (ALD). Based on the evidence for agglomeration of ZrO{sub 2} on SiO{sub 2} a method was introduced, which takes local thickness variations into account during the simulation of the HR-RBS spectra. An accurate statement about the ZrO{sub 2}/SiO{sub 2} interface was

  17. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0 ... for capacity losses in lithium ion cells and lithium-alloy cells....

  18. Growth of LiMn{sub 2}O{sub 4} thin films by pulsed-laser deposition and their electrochemical properties in lithium microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Julien, C. [Univ. Pierre et Marie Curie, Paris (France). LMDH; Haro-Poniatowski, E. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico); Camacho-Lopez, M.A. [LMDH, UMR 7603, Universite Pierre et Marie Curie, 4 place Jussieu, 75252, Paris (France); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico (Mexico); Jimenez-Jarquin, J. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico)

    2000-03-01

    Films of LiMn{sub 2}O{sub 4} were grown by pulsed-laser deposition (PLD) onto silicon wafers using sintered targets which consisted in the mixture of LiMn{sub 2}O{sub 4} and Li{sub 2}O powders. The film formation has been studied as a function of the preparation conditions, i.e. composition of the target, substrate temperature, and oxygen partial pressure in the deposition chamber. Composition, morphology and structural properties of PLD films have been investigated using Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray diffraction and Raman scattering spectroscopy. The films deposited from target LiMn{sub 2}O{sub 4}+15% Li{sub 2}O have an excellent crystallinity when deposited onto silicon substrate maintained at 300 C in an oxygen partial pressure of 100 mTorr. It is found that such a film crystallizes in the spinel structure (Fd3m symmetry) as evidenced by X-ray diffraction. Well-textured polycrystalline films exhibit crystallite size of 300 nm. Pulsed-laser deposited LiMn{sub 2}O{sub 4} thin films obtained with a polycrystalline morphology were successfully used as cathode materials in lithium microbatteries. The Li//LiMn{sub 2}O{sub 4} thin film cells have been tested by cyclic voltammetry and galvanostatic charge-discharge techniques in the potential range 3.0-4.2 V. Specific capacity as high as 120 mC/cm{sup 2} {mu}m was measured on polycrystalline films. The chemical diffusion coefficients for the Li{sub x}Mn{sub 2}O{sub 4} thin films appear to be in the range of 10{sup -11}-10{sup -12} cm{sup 2}/s. Electrochemical measurements show a good cycleability of PLD films when cells are charged-discharged at current densities of 5-25 {mu}A/cm{sup 2}. (orig.)

  19. Prediction of deviations from the Rutherford formula for low-energy Coulomb scattering of wavepackets

    Science.gov (United States)

    Hoffmann, Scott E.

    2017-11-01

    We calculate the nonrelativistic scattering of a wavepacket from a Coulomb potential and find deviations from the Rutherford formula in all cases. These generally occur only at low scattering angles, where they would be obscured by the part of the incident beam that emerges essentially unscattered. For a model experiment, the scattering of helium nuclei from a thin gold foil, we find the deviation region is magnified for low incident energies (in the keV range), so that a large shadow zone of low probability around the forward direction is expected to be measurable. From a theoretical perspective, the use of wavepackets makes partial wave analysis applicable to this infinite-range potential. It allows us to calculate the everywhere finite probability for a wavepacket to wavepacket transition and to relate this to the differential cross section. Time delays and advancements in the detection probabilities can be calculated. We investigate the optical theorem as applied to this special case.

  20. Application of the Bayesian analysis to the modified Rutherford equation for NTM stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Urso, L; Fischer, R [MPI fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching, EURATOM-Association (Germany); Isayama, A, E-mail: laura.urso@ipp.mpg.d [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan)

    2010-05-15

    The determination of the free parameters present in the modified Rutherford equation (MRE), which is routinely used for studying the physics of neoclassical tearing mode (NTM) stabilization, is addressed by making use of the Bayesian probability theory. The evaluation of the free coefficients is particularly sensitive to the assumptions used in the modelled equation, to the correlation of various physical parameters and to the uncertainties of the experimental measurements. A probabilistic method was applied for the consistent evaluation of the coefficients and their uncertainties using a large database of discharges and by considering the correlations and the uncertainties of the multiple physical quantities present in the MRE. The estimated values and uncertainties of the coefficients are related to the precise determination of the minimum amount of electron cyclotron current drive power necessary to stabilize NTMs in the International Thermonuclear Experimental Reactor.

  1. Dimensional Changes of Nb3Sn Rutherford Cables During Heat Treatment

    CERN Document Server

    Rochepault, E; Ambrosio, G; Anerella, M; Ballarino, A; Bonasia, A; Bordini, B; Cheng, D; Dietderich, D R; Felice, H; Garcia Fajardo, L; Ghosh, A; Holik, E F; Izquierdo Bermudez, S; Perez, J C; Pong, I; Schmalzle, J; Yu, M

    2016-01-01

    In high field magnet applications, Nb3Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb3Sn phase change. In order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. This paper summarizes measurements of dimensional changes on strands, single Rutherford cables, cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb3Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.

  2. Bathymetry and acoustic backscatter: Estero Bay, California

    Science.gov (United States)

    Hartwell, Stephen R.; Finlayson, David P.; Dartnell, Peter; Johnson, Samuel Y.

    2013-01-01

    Between July 30 and August 9, 2012, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from Estero Bay, San Luis Obispo, California, under PCMSC Field Activity ID S-05-12-SC. The survey was done using the R/V Parke Snavely outfitted with a multibeam sonar for swath mapping and highly accurate position and orientation equipment for georeferencing. This report provides these data in a number of different formats, as well as a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

  3. Core-suppressed AC loss and strand-moderated contact resistance in a Nb-Sn Rutherford cable

    NARCIS (Netherlands)

    Sumption, M.D.; Collings, E.W.; Scanlan, R.M.; Nijhuis, Arend; ten Kate, Herman H.J.

    1999-01-01

    Calorimetric measurements of AC loss and hence interstrand contact resistance (ICR), have been performed on two types of Rutherford cable wound with unplated Nb3Sn strand. One of the cable types was furnished with a thin core of AISI 316L stainless steel and the other was left uncored. The cables

  4. Electrochemical cell

    Science.gov (United States)

    Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

    1992-01-01

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

  5. Benchmark measurements of non-Rutherford proton elastic scattering cross section for boron

    Energy Technology Data Exchange (ETDEWEB)

    Chiari, M. [INFN-Sezione di Firenze, Sesto Fiorentino, Florence I-50019 (Italy); Bianconi, M. [CNR-IMM-UOS di Bologna, Bologna I-40129 (Italy); Bogdanović Radović, I. [Ruder Boskovic Institute, Zagreb 10002 (Croatia); Mayer, M. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-01-15

    In the literature several elastic scattering cross-sections data sets are available for protons on {sup 10}B and {sup 11}B at energies and scattering angles suitable for elastic backscattering spectrometry (EBS) analysis. However, agreement between these different data sets is generally poor, with systematic differences up to 20%, well beyond the stated absolute uncertainties. To resolve the conflict between the different data sets in the absence of the evaluated cross-section data, a benchmark experiment was performed. Proton backscattering spectra were obtained with a thick uniform B{sub 4}C target at beam energies in the range of 2.0–4.0 MeV and at different scattering angles, followed by a standard direct simulation with the SIMNRA code using the available experimental cross-section data. As a result, recommendation on the most appropriate data set to be used in proton EBS analysis of boron is given.

  6. Computer simulation of backscattering spectra from paint

    Science.gov (United States)

    Mayer, M.; Silva, T. F.

    2017-09-01

    To study the role of lateral non-homogeneity on backscattering analysis of paintings, a simplified model of paint consisting of randomly distributed spherical pigment particles embedded in oil/binder has been developed. Backscattering spectra for lead white pigment particles in linseed oil have been calculated for 3 MeV H+ at a scattering angle of 165° for pigment volume concentrations ranging from 30 vol.% to 70 vol.% using the program STRUCTNRA. For identical pigment volume concentrations the heights and shapes of the backscattering spectra depend on the diameter of the pigment particles: This is a structural ambiguity for identical mean atomic concentrations but different lateral arrangement of materials. Only for very small pigment particles the resulting spectra are close to spectra calculated supposing atomic mixing and assuming identical concentrations of all elements. Generally, a good fit can be achieved when evaluating spectra from structured materials assuming atomic mixing of all elements and laterally homogeneous depth distributions. However, the derived depth profiles are inaccurate by a factor of up to 3. The depth range affected by this structural ambiguity ranges from the surface to a depth of roughly 0.5-1 pigment particle diameters. Accurate quantitative evaluation of backscattering spectra from paintings therefore requires taking the correct microstructure of the paint layer into account.

  7. Simulation of ultrasound backscatter images from fish

    DEFF Research Database (Denmark)

    Pham, An Hoai; Stage, Bjarne; Hemmsen, Martin Christian

    2011-01-01

    The objective of this work is to investigate ultrasound (US) backscatter in the MHz range from fis to develop a realistic and reliable simulation model. The long term objective of the work is to develop the needed signal processing for fis species differentiation using US. In in-vitro experiments...... images reproduce most of the important characteristics of the measured US image....

  8. Backscatter C [8101]--Offshore of San Francisco, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of San Francisco map area, California. Backscatter data are provided as separate...

  9. Backscatter B [7125]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  10. BackscatterB [EM300]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  11. BackscatterC [7125]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  12. BackscatterB [7125]--Offshore Scott Creek, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Scott Creek map area, California. Backscatter data are provided as three separate...

  13. Backscatter A [8101]--Offshore of San Francisco, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of San Francisco map area, California. Backscatter data are provided as separate...

  14. BackscatterC [SWATH]--Offshore Pigeon Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pigeon Point map area, California. Backscatter data are provided as three separate...

  15. BackscatterC [SWATH]--Offshore Scott Creek, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Scott Creek map area, California. Backscatter data are provided as three separate...

  16. Backscatter A [8101]--Drakes Bay and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Drakes bay and Vicinity map area, California. Backscatter data are provided as separate grids...

  17. BackscatterB [EM300]--Offshore Aptos, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Aptos map area, California. Backscatter data are provided as two separate grids...

  18. BackscatterA [8101]--Offshore Scott Creek, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Scott Creek map area, California. Backscatter data are provided as three separate...

  19. BackscatterB [7125]--Offshore Pigeon Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pigeon Point map area, California. Backscatter data are provided as three separate...

  20. Backscatter C [Swath]--Offshore of Tomales Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Tomales Point map area, California. Backscatter data are provided as separate...

  1. BackscatterA [SWATH]--Offshore Aptos, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Aptos map area, California. Backscatter data are provided as two separate grids...

  2. Backscatter A [8101]--Offshore Half Moon Bay, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Half Moon Bay map area, California. Backscatter data are provided as two...

  3. Backscatter B [8101]--Offshore of San Francisco, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of San Francisco map area, California. Backscatter data are provided as separate...

  4. Backscatter A [8101]--Offshore of Bodega Head, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Bodega Head map area, California. Backscatter data are provided as separate...

  5. Backscatter C [7125]--Drakes Bay and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Drakes bay and Vicinity map area, California. Backscatter data are provided as separate grids...

  6. Backscatter D [USGS]--Offshore of Tomales Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Tomales Point map area, California. Backscatter data are provided as separate...

  7. Backscatter B [7125]--Offshore Half Moon Bay, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Half Moon Bay map area, California. Backscatter data are provided as two...

  8. BackscatterA [8101]--Offshore Pigeon Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pigeon Point map area, California. Backscatter data are provided as three separate...

  9. Backscatter C [Swath]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  10. Backscatter D [7125]--Offshore of San Francisco, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of San Francisco map area, California. Backscatter data are provided as separate...

  11. Preliminary backscatter results from the hydrosweep multibeam system

    Digital Repository Service at National Institute of Oceanography (India)

    Hagen, R.A.; Chakraborty, B.; Schenke, H.W.

    to 120 degrees, but also adds two new capabilities to the system: collection of sidescan sonar data, and the measurement of seafloor backscatter coefficients. The Hydrosweep backscatter software uses an algorithm developEd. by the Scripps Institution...

  12. Contribution of backscattered electrons to the total electron yield ...

    Indian Academy of Sciences (India)

    It is shown experimentally that under energetic electron bombardment the backscattered electrons from solid targets contribute significantly (∼ 80%) to the observed total electron yield, even for targets of high backscattering coefficients. It is further found that for tungsten ( = 74) with a backscattering coefficient of about 0.50 ...

  13. Electrochemical attosyringe

    Science.gov (United States)

    Laforge, François O.; Carpino, James; Rotenberg, Susan A.; Mirkin, Michael V.

    2007-01-01

    The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10−18 to 10−12 liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems. PMID:17620612

  14. Electrochemical attosyringe.

    Science.gov (United States)

    Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

    2007-07-17

    The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

  15. Experimental results of current distribution in Rutherford-type LHC cables

    CERN Document Server

    Verweij, A P

    2000-01-01

    Current distribution among the wires of multi-strand superconducting cables is an important item for accelerator magnets. A non-uniform distribution could cause additional field distortions in the magnet bore and can as well be one of the reasons of premature quenching. Since two years electrical measurements on superconducting Rutherford-type cables are performed at CERN as part of the reception tests for the Large Hadron Collider (LHC). Cable samples of 2.4 m length are tested at currents up to 32 kA, temperatures around 1.9 and 4.3 K, and fields up to 10 T, applied perpendicularly as well as parallel to the broad face of the cable. Last year, an array of 24 Hall probes was installed in the test set-up in order to measure the self-field of the cable samples along one cable pitch. Each of the probes measures the local field generated by the current in the strands close by, and the results of the all probes reflect therefore the distribution of the strand currents. Experiments are done varying the applied fie...

  16. Current distribution inside Rutherford-type superconducting cables and impact on performance of LHC dipoles

    CERN Document Server

    Schreiner, T

    2002-01-01

    The windings of high--field superconducting accelerator magnets are usually made of Rutherford--type cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. Such a Periodic Field Pattern (PFP) has already been observed in number of superconducting accelerator magnets. Additional unbalanced currents in individual strands of the cable appear to be causing this effect. The present thesis describes the investigation of the PFPs performed with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in the small--scale model magnets with a length of one meter and in full--scale prototypes and pre--series magnets with fifteen meters of length. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. One of the main parameters influencing the properties of the PFP is the cross--...

  17. Interstrand and AC-loss measurements on Rutherford-type cables for accelerator magnet applications

    CERN Document Server

    Otmani, R; Tixador, P

    2001-01-01

    One of the main issues for particle accelerator magnets is the control of interstrand resistances. Too low resistances result in large coupling currents during ramping, which distort field quality, while too large resistances may prevent current redistribution among cable strands, resulting in degraded quench performance. In this paper, we review a series of interstrand resistance and AC-loss measurements performed on four Rutherford-type cables. The four cables have the same number of strands and similar outer dimensions, corresponding to LHC quadrupole cable specifications. The first cable is made from NbTi strands, coated with silver-tin alloy, the second one is made from bare Nb/sub 3/Sn strands, the third one is made also from bare Nb/sub 3/Sn strands but includes a 25- mu m-thick stainless steel core between the strand layers, and the last one is made from Nb/sub 3/Sn strands plated with chromium. To cross-check the two measurement types and assess their consistency, we compare the coupling-current time...

  18. Target studies for the neutrino factory at the Rutherford Appleton laboratory

    CERN Document Server

    Drumm, P V; Bennett, R

    2001-01-01

    Target studies at the Rutherford Appleton Laboratory have concentrated on studies of a solid heavy metal target. The suggestion to use a radiatively cooled target which rotates in beam was made shortly after the first NuFact workshop as a means of dissipating large amounts of power at a high temperature, and as an alternative to the proposed water-cooled rotating band and liquid metal jet targets. This paper examines the proposed drive scheme for the target ring, which uses induced currents and magnetic forces to both levitate and drive the target. Estimates of the power required to levitate and drive the target ring and the forces exerted on the moving ring as it enters the target capture solenoid are given. One of the principle concerns in the operation of a solid target is the severe shock stress experienced due to the impact of an intense energetic proton beam in a short time compared to the transit time of sound in the material. Calculations of the stresses induced in the target ring and their evolution ...

  19. submitter Geometrical Behavior of $Nb_{3}Sn$ Rutherford Cables During Heat Treatment

    CERN Document Server

    Durante, Maria; Ferracin, Paolo; Manil, Pierre; Perez, Juan Carlos; Rifflet, Jean-Michel; Rondeaux, Francoise

    2016-01-01

    In $Nb_{3}Sn$ accelerator magnets, non-superconducting precursor cables are wound into their final coil shape and then heat treated at a high temperature to form the A15 superconducting phase. The growth of cable strands during reaction and the differential thermal dilatation in the coil components lead to both stress in the cable and geometrical deformations of the winding, with possible consequences on magnet performances. An experimental campaign on different types of Rutherford cables has been carried out at CEA Saclay, in collaboration with CERN, in order to measure cable dimension changes in all directions, with respect to cable configuration and winding geometry. A 700-mm-long versatile test bench has been designed for several cable topologies up to 22 mm in width. This paper describes the tooling and presents the results of the experimental campaign led on the cables, made of powder-in-tube and restacked-rod-process strands, of FRESCA2, a 13-T dipole magnet

  20. Characterization of Nb3Sn Rutherford cables for the LHC 11-T Dipole Magnet

    CERN Document Server

    Wuis, A J; Ballarino, A; Oberli, L; Ten Kate, H H J

    2013-01-01

    The so-called CERN-LHC DS upgrade relies on the use of 11 T dipole magnets. For these magnets 40 strands Nb3Sn type Rutherford cables based on 0.7 mm wires are being developed. Recently four samples of the cables were characterized in the CERN FRESCA cable test station. The critical current and the premature quench current due to magneto-thermal instability were measured at 1.9 K and 4.3 K in a background magnetic field between 0 and 9.6 T (the peak magnetic field on the conductor, including the self-field of the cable, ranges from ~ 2 T to ~ 12 T). Two cable samples were based on Powder-In-Tube (PIT) wire and two on Restacked-Rod-Process (RRP) wire. The PIT samples were identical and without a core in the cable while one of the RRP samples features a 25 μm thick stainless steel core. All cables samples tested have a width and a thickness of about 14.7 mm and 1.25 mm, respectively. Cables and sample holders were manufactured at CERN. In this paper we report and discuss the cable test results and compare them...

  1. Influence of strand surface condition on interstrand contact resistance and coupling loss in NbTi-wound Rutherford cables

    CERN Document Server

    Sumption, M D; Scanlan, R M; Nijhuis, A; ten Kate, H H J; Kim, S W; Wake, M; Shintomi, T

    1999-01-01

    Presented in this work are the results of directly measured and AC- loss-derived interstrand contact resistance (ICR) measurements performed magnetically or resistively on bare-Cu and coated-strand pairs, calorimetrically on $9 11-strand Rutherford cables wound with strands that had been coated with various metallic and insulating layers, and calorimetrically and magnetically on 28-strand Rutherford cables (LHC-type) wound with bare-Cu-, Ni-, and $9 stabrite-plated strands. Comparisons are made of the effects of various conditions of heat treatment, HT (time and temperature), and pressure (applied during HT and then either maintained or re-applied during measurement). The $9 resulting ICRs are compared and interpreted in terms of the oxide layer on the strand coating and its response to curing conditions. (66 refs).

  2. Dosimetric characteristics of backscattered electrons in lead

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Calatayud, Jose; Carmona, Vicente [Physics section, Radiation Oncology Department, ' La Fe' University Hospital, Avda Campanar 21, E-46009 Valencia (Spain); Ballester, Facundo [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, C/ Dr. Moliner 50, E-46100 Burjassot (Spain); IFIC-Instituto de Fisica Corpuscular, CSIC-Universitat de Valencia, C/ Dr. Moliner 50, E-46100 Burjassot (Spain). E-mail: Facundo.Ballester at uv.es; Serrano, Miguel A.; Lluch, Jose L. [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, C/ Dr. Moliner 50, E-46100 Burjassot (Spain); Casal, Emilio [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, C/ Dr. Moliner 50, E-46100 Burjassot (Spain); CND, Centro Nacional de Dosimetria, Avda. Campanar 21, E-46009 Valencia (Spain)

    2000-07-01

    In electron beam therapy, tissue overdose due to electrons backscattered from lead has been profusely studied. To quantify this dose enhancement effect, an electron backscatter factor (EBF) wasdefined as the ratio of dose at the tissue-inhomogeneity interface with and without the scatterer present. The dependence of the EBF on energy at the scatterer surface is not well known for energies lower than 3 MeV which is the most frequent clinical situation. In this work, we have done Monte Carlo calculations with the GEANT code to study EBF in lead at this energy range. The applicability of this code and the developed procedure for dose estimation has been experimentally verified. The dependence of the EBF on the beam energy incident on the scatterer has been studied for different nominal beam energies incident at the phantom's surface. The results show a trend of increase of EBF with the beam energy incident on the scatterer between 0.5 and 1.5 MeV, keeping practically constant above this energy up to 3 MeV. Backscattered electron energy spectra and depth dose curves in the 'up-stream' direction have been obtained at the various energies of the primary electron beam striking on the lead scatterer. The results of this work are compared with previously published data. (author)

  3. Backscatter Correction Algorithm for TBI Treatment Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Nieto, B.; Sanchez-Doblado, F.; Arrans, R.; Terron, J.A. [Dpto. Fisiología Médica y Biofísica, Universidad de Sevilla, Avda. Sánchez Pizjuán, 4. E-41009, Sevilla (Spain); Errazquin, L. [Servicio Oncología Radioterápica, Hospital Univ.V. Macarena. Dr. Fedriani, s/n. E-41009, Sevilla (Spain)

    2015-01-15

    The accuracy requirements in target dose delivery is, according to ICRU, ±5%. This is so not only in standard radiotherapy but also in total body irradiation (TBI). Physical dosimetry plays an important role in achieving this recommended level. The semi-infinite phantoms, customarily used for dosimetry purposes, give scatter conditions different to those of the finite thickness of the patient. So dose calculated in patient’s points close to beam exit surface may be overestimated. It is then necessary to quantify the backscatter factor in order to decrease the uncertainty in this dose calculation. The backward scatter has been well studied at standard distances. The present work intends to evaluate the backscatter phenomenon under our particular TBI treatment conditions. As a consequence of this study, a semi-empirical expression has been derived to calculate (within 0.3% uncertainty) the backscatter factor. This factor depends lineally on the depth and exponentially on the underlying tissue. Differences found in the qualitative behavior with respect to standard distances are due to scatter in the bunker wall close to the measurement point.

  4. Periodicity of crossover currents in a Rutherford-type cable subjected to a time-dependent magnetic field. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Akhmetov, A.; Devred, A. [Superconducting Super Collider Lab., Dallas, TX (United States); Ogitsu, T. [Superconducting Super Collider Lab., Dallas, TX (United States)]|[National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1993-09-01

    The behavior Of Rutherford-type cables under a time-dependent magnetic field is studied. Existing models are extended describing the currents flowing through the resistive contacts at the crossovers between the cable strands by considering crossover current distributions which are not uniform along the cable axis. The generalized system of equations are applied to a few cases of practical interest and show that, if not uniform, the crossover current distribution is periodic, with a period equal to the cable pitch length.

  5. Backscatter and attenuation characterization of ventricular myocardium

    Science.gov (United States)

    Gibson, Allyson Ann

    2009-12-01

    This Dissertation presents quantitative ultrasonic measurements of the myocardium in fetal hearts and adult human hearts with the goal of studying the physics of sound waves incident upon anisotropic and inhomogeneous materials. Ultrasound has been used as a clinical tool to assess heart structure and function for several decades. The clinical usefulness of this noninvasive approach has grown with our understanding of the physical mechanisms underlying the interaction of ultrasonic waves with the myocardium. In this Dissertation, integrated backscatter and attenuation analyses were performed on midgestational fetal hearts to assess potential differences in the left and right ventricular myocardium. The hearts were interrogated using a 50 MHz transducer that enabled finer spatial resolution than could be achieved at more typical clinical frequencies. Ultrasonic data analyses demonstrated different patterns and relative levels of backscatter and attenuation from the myocardium of the left ventricle and the right ventricle. Ultrasonic data of adult human hearts were acquired with a clinical imaging system and quantified by their magnitude and time delay of cyclic variation of myocardial backscatter. The results were analyzing using Bayes Classification and ROC analysis to quantify potential advantages of using a combination of two features of cyclic variation of myocardial backscatter over using only one or the other feature to distinguish between groups of subjects. When the subjects were classified based on hemoglobin A1c, the homeostasis model assessment of insulin resistance, and the ratio of triglyceride to high-density lipoprotein-cholesterol, differences in the magnitude and normalized time delay of cyclic variation of myocardial backscatter were observed. The cyclic variation results also suggested a trend toward a larger area under the ROC curve when information from magnitude and time delay of cyclic variation is combined using Bayes classification than when

  6. An Ultrasonic Backscatter Instrument for Cancellous Bone Evaluation in Neonates

    Directory of Open Access Journals (Sweden)

    Chengcheng Liu

    2015-09-01

    Full Text Available Ultrasonic backscatter technique has shown promise as a noninvasive cancellous bone assessment tool. A novel ultrasonic backscatter bone diagnostic (UBBD instrument and an in vivo application for neonatal bone evaluation are introduced in this study. The UBBD provides several advantages, including noninvasiveness, non-ionizing radiation, portability, and simplicity. In this study, the backscatter signal could be measured within 5 s using the UBBD. Ultrasonic backscatter measurements were performed on 467 neonates (268 males and 199 females at the left calcaneus. The backscatter signal was measured at a central frequency of 3.5 MHz. The delay (T1 and duration (T2 of the backscatter signal of interest (SOI were varied, and the apparent integrated backscatter (AIB, frequency slope of apparent backscatter (FSAB, zero frequency intercept of apparent backscatter (FIAB, and spectral centroid shift (SCS were calculated. The results showed that the SOI selection had a direct influence on cancellous bone evaluation. The AIB and FIAB were positively correlated with the gestational age (|R| up to 0.45, P10 µs. Moderate positive correlations (|R| up to 0.45, P10 µs. The T2 mainly introduced fluctuations in the observed correlation coefficients. The moderate correlations observed with UBBD demonstrate the feasibility of using the backscatter signal to evaluate neonatal bone status. This study also proposes an explicit standard for in vivo SOI selection and neonatal cancellous bone assessment.

  7. Structural effects of metallic chromium on its electrochemical behavior

    Directory of Open Access Journals (Sweden)

    VELIMIR RADMILOVIC

    2007-06-01

    Full Text Available Chromium dissolution in aqueous sulfuric acid solution of pH 1 was studied electrochemically on chromium electrodes with different crystallographic structures. A slow potentiodynamic method was used for the electrochemical measurements in deaerated solutions (purgedwith nitrogen,while the Cr(III ions in the solution after the corrosion were determined by atomic absorption spectrometry. Three electrode materials with a very dominant crystallite orientation resembling single crystal structures (i.e., 111 and 110 confirmed by the electron backscattering diffraction (EBSD, were used in the experiments. The (111 structures were somewhat more active electrochemically (both anodic and cathodic than the (110 structure. However, Cr electrochemically deposited in standard plating bath, assumed from literature data to has also the (111 structure, was more than 4 times active for anodic dissolution and, by the same number, less active for cathodic hydrogen evolution. The concentrations of Cr(III ions determined in the solution after definite times of corrosion of all the materials showed almost two times larger dissolution rates than observed electrochemically by three different electrochemical methods (Wagner–Traud, Stern–Geary, electrochemical impedance spectroscopy. This is explained by the simultaneous occurrence of potential independent chemical dissolution of Cr, by a direct reaction of metallic Cr with H2O molecules, proposed a long time ago by Kolotyrkin and coworkers.

  8. Interactive computer analysis of nuclear backscattering spectra

    Science.gov (United States)

    Saunders, Philip A.; Ziegler, J. F.

    1983-12-01

    A review will be made of a computer-based interactive nuclear backscattering analysis system. Users without computer experience can develop moderate competence with the system after only brief instruction because of the menu-driven organization. Publishable quality figures can be obtained without any computer expertise. Among the quantities which can be displayed over the data are depth scales for any element, element identification, relative concentrations and theoretical spectra. Captions and titling can made from a selection of 30 font styles. Lettering is put on the graphs under joy-stick control such that placement is exact without needing complicated commands.

  9. Elementary polarization properties in the backscattering configuration.

    Science.gov (United States)

    Arteaga, Oriol; Garcia-Caurel, Enric; Ossikovski, Razvigor

    2014-10-15

    In the normal incidence backscattering configuration, a polarimetric measurement always preserves the reciprocal symmetry. For a reciprocal Jones matrix, the number of elementary polarization properties is reduced from six to four. In this work, the physical interpretation of these properties is examined and they are compared with the equivalent polarization properties in transmission. It is found that, with the exception of natural optical activity, a polarimetric backreflection experiment can essentially provide the same type of information about the anisotropy of a medium as a transmission analysis, although transmission and backreflection information comes in a completely different form. Experimental examples are provided to illustrate the discussion.

  10. Seafloor backscatter signal simulation and classification

    Digital Repository Service at National Institute of Oceanography (India)

    Mahale, V.; El Dine, W.G.; Chakraborty, B.

    in the backscattered signal. An analysis of the signal envelope fluctuation over several pings can be used to understand the roughness characteristics of the seafloor. In this, primary effort towards classification, we have concentrated only on the normal incidence... in such situations is to use the ground truth data to derive the type of class. Most of these problems are of supervised learning type, i.e. it requires examples of known class types, for the network learning process. In a typical scenario, a neural network...

  11. Reducing parametric backscattering by polarization rotation

    CERN Document Server

    Barth, Ido

    2016-01-01

    When a laser passes through underdense plasmas, Raman and Brillouin Backscattering can reflect a substantial portion of the incident laser energy. This is a major loss mechanism, for example, in inertial confinement fusion. However, by slow rotation of the incident linear polarization, the overall reflectivity can be reduced significantly. Particle in cell simulations show that, for parameters similar to those of indirect drive fusion experiments, polarization rotation reduces the reflectivity by a factor of $5$. A general, fluid-model based, analytical estimation for the reflectivity reduction agrees with simulations.

  12. The aCORN backscatter-suppressed beta spectrometer

    Science.gov (United States)

    Hassan, M. T.; Bateman, F.; Collett, B.; Darius, G.; DeAngelis, C.; Dewey, M. S.; Jones, G. L.; Komives, A.; Laptev, A.; Mendenhall, M. P.; Nico, J. S.; Noid, G.; Stephenson, E. J.; Stern, I.; Trull, C.; Wietfeldt, F. E.

    2017-09-01

    Backscatter of electrons from a beta detector, with incomplete energy deposition, can lead to undesirable effects in many types of experiments. We present and discuss the design and operation of a backscatter-suppressed beta spectrometer that was developed as part of a program to measure the electron-antineutrino correlation coefficient in neutron beta decay (aCORN). An array of backscatter veto detectors surrounds a plastic scintillator beta energy detector. The spectrometer contains an axial magnetic field gradient, so electrons are efficiently admitted but have a low probability for escaping back through the entrance after backscattering. The design, construction, calibration, and performance of the spectrometer are discussed.

  13. Microfluidic electrochemical reactors

    Science.gov (United States)

    Nuzzo, Ralph G [Champaign, IL; Mitrovski, Svetlana M [Urbana, IL

    2011-03-22

    A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

  14. Chiral Receiving Antenna With Low Backscattering Levels

    CERN Document Server

    Karilainen, Antti O

    2011-01-01

    Receiving antennas absorb power from incident waves, but they also re-radiate some power into surrounding space. If a receiving antenna is to be used as a sensor which should not disturb the object under study, it should scatter as little power as possible in the receiving direction. We propose to use a chiral element composed of two orthogonal chiral particles as a low-scattering sensor.The element can transmit and receive circular polarization in all directions with the Huygens' pattern. We derive the vector effective length for the antenna using the small dipole approximation for the chiral particles. We observe that the element does not backscatter, regardless of the polarization, when the incidence direction is normal to the plane of the particles. Scattered fields, scattered axial ratio, and the scattering cross section are presented. We show that the zero-backscattering property holds also for the antenna element when it is capable to receive all the available power with conjugate loading. The approxim...

  15. Separators for electrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Steven Allen; Anakor, Ifenna Kingsley; Farrell, Greg Robert

    2018-01-16

    Provided are separators for use in an electrochemical cell comprising (a) an inorganic oxide and (b) an organic polymer, wherein the inorganic oxide comprises organic substituents. Also provided are electrochemical cells comprising such separators.

  16. Electrochemical kinetics theoretical aspects

    CERN Document Server

    Vetter, Klaus J

    1967-01-01

    Electrochemical Kinetics: Theoretical Aspects focuses on the processes, methodologies, reactions, and transformations in electrochemical kinetics. The book first offers information on electrochemical thermodynamics and the theory of overvoltage. Topics include equilibrium potentials, concepts and definitions, electrical double layer and electrocapillarity, and charge-transfer, diffusion, and reaction overvoltage. Crystallization overvoltage, total overvoltage, and resistance polarization are also discussed. The text then examines the methods of determining electrochemical reaction mechanisms

  17. Bottom Backscattering Strengths Measured in Shallow and Deep Water

    Science.gov (United States)

    2017-01-18

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/7160--17-9701 Bottom Backscattering Strengths Measured in Shallow and Deep Water January...LIMITATION OF ABSTRACT Bottom Backscattering Strengths Measured in Shallow and Deep Water Roger C. Gauss,1 Edward L. Kunz,1 Joseph M. Fialkowski...2 3 B2001 (SHALLOW WATER − NEW JERSEY SHELF) .............................. 4

  18. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between B = 50 eV and 5000 eV. The angle of incidence α and take-off angle are chosen to have ...

  19. Initial backscatter occurrence statistics from the CUTLASS HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available A statistical study of the occurrence of ground and ionospheric backscatter within the fields-of-view of the CUTLASS HF radars, at an operating frequency of 10 MHz, during the first 20 months of operation has been undertaken. The diurnal variation of the occurrence of backscatter and the range at which such backscatter is observed is found to be highly dependent on seasonal changes of the ionospheric electron density in both the E and F region, determined from ionosonde observations. In general, ionospheric backscatter is observed at far ranges during the local day in winter months and at near ranges during the local night in summer months. The Iceland radar observes more near-range E region backscatter than the Finland radar as a consequence of its more zonal look-direction. The dependence of the occurrence of backscatter on geomagnetic activity and radar operating frequency are also investigated. The occurrence of ground and ionospheric backscatter is discussed in terms of HF propagation modes and ionospheric electron densities as well as geophysical processes. A brief assessment of the possible impact of solar cycle variations on the observations is made and frequency management is discussed. Such a study, with its focus on the `instrumental' aspect of backscatter occurrence, is essential for a full interpretation of HF coherent radar observations.

  20. Strong Localization in Disordered Media: Analysis of the Backscattering Cone

    KAUST Repository

    Delgado, Edgar

    2012-06-01

    A very interesting effect in light propagation through a disordered system is Anderson localization of light, this phenomenon emerges as the result of multiple scattering of waves by electric inhomogeneities like spatial variations of index of refraction; as the amount of scattering is increased, light propagation is converted from quasi-diffusive to exponentially localized, with photons confined in a limited spatial region characterized by a fundamental quantity known as localization length. Light localization is strongly related to another interference phenomenon emerged from the multiple scattering effect: the coherent backscattering effect. In multiple scattering of waves, in fact, coherence is preserved in the backscattering direction and produces a reinforcement of the field flux originating an observable peak in the backscattered intensity, known as backscattering cone. The study of this peak provide quantitative information about the transport properties of light in the material. In this thesis we report a complete FDTD ab-initio study of light localization and coherent backscattering. In particular, we consider a supercontinuum pulse impinging on a sample composed of randomly positioned scatterers. We study coherent backscattering by averaging over several realizations of the sample properties. We study then the coherent backscattering cone properties as the relative permittivity of the sample is changed, relating the latter with the light localization inside the sample. We demonstrate important relationships between the width of the backscattering cone and the localization length, which shows a linear proportionality in the strong localization regime.

  1. Over-the-horizon backscatter radar

    Science.gov (United States)

    Stiglitz, Martin R.; Blanchard, Christine

    1990-05-01

    This paper describes a recently constructed over-the-horizon backscatter (OTH-B) radar system covering as many as 4,800,000 sq nautical miles over a distance of 1800 nautical miles. This HF system operates at frequencies from 5 to 28 MHz. The radar's 3630-ft-long transmitting antenna is divided into six subarrays to accommodate different operating frequencies. Three sets of these arrays are located at the east coast radar system transmit site near Moscow, Maine. The transmitter is powered by 12 10-kW tubes per sector, emitting 360 kW of radiated RF power. The signal processing software correlates the receiver radar track data with flight patterns of unknown aircraft and flight plans of friendly aircraft; twenty-nine computers perform the signal analysis and processing function of the receiver.

  2. Reducing parametric backscattering by polarization rotation

    Science.gov (United States)

    Barth, Ido; Fisch, Nathaniel

    2016-10-01

    When a laser passes through underdense plasmas, Raman and Brillouin Backscattering can reflect a substantial portion of the incident laser energy. This is a major loss mechanism, for example, in inertial confinement fusion. However, by slow rotation of the incident linear polarization, the overall reflectivity can be reduced significantly. Particle in cell simulations show that, for parameters similar to those of indirect drive fusion experiments, polarization rotation reduces the reflectivity by a factor of 5. A general, fluid-model based, analytical estimation for the reflectivity reduction agrees with simulations. This work was supported by NNSA Grant No. DE- NA0002948, AFOSR Grant No. FA9550-15-1-0391, and DOE Contract No. DE-AC02-09CH11466.

  3. Electron backscatter diffraction in materials characterization

    Directory of Open Access Journals (Sweden)

    Dejan Stojakovic

    2012-03-01

    Full Text Available Electron Back-Scatter Diffraction (EBSD is a powerful technique that captures electron diffraction patterns from crystals, constituents of material. Captured patterns can then be used to determine grain morphology, crystallographic orientation and chemistry of present phases, which provide complete characterization of microstructure and strong correlation to both properties and performance of materials. Key milestones related to technological developments of EBSD technique have been outlined along with possible applications using modern EBSD system. Principles of crystal diffraction with description of crystallographic orientation, orientation determination and phase identification have been described. Image quality, resolution and speed, and system calibration have also been discussed. Sample preparation methods were reviewed and EBSD application in conjunction with other characterization techniques on a variety of materials has been presented for several case studies. In summary, an outlook for EBSD technique was provided.

  4. CHANGES OF BACKSCATTERING PARAMETERS DURING CHILLING INJURY IN BANANAS

    Directory of Open Access Journals (Sweden)

    NORHASHILA HASHIM

    2014-06-01

    Full Text Available The change in backscattering parameters during the appearance of chilling injury in bananas was investigated. Bananas were stored at a chilling temperature for two days and the degrees of the chilling injuries that appeared were measured before, during and after storage using backscattering imaging and visual assessment. Laser lights at 660 nm and 785 nm wavelengths were shot consecutively onto the samples in a dark room and a camera was used to capture the backscattered lights that appeared on the samples. The captured images were analysed and the changes of intensity against pixel count were plotted into graphs. The plotted graph provides useful information of backscattering parameters such as inflection point (IP, slope after inflection point (SA, and full width at half maximum (FWHM and saturation radius (RSAT. Results of statistical analysis indicated that there were significant changes of these backscattering parameters as chilling injury developed.

  5. A full-angle Monte-Carlo scattering technique including cumulative and single-event Rutherford scattering in plasmas

    Science.gov (United States)

    Higginson, Drew P.

    2017-11-01

    We describe and justify a full-angle scattering (FAS) method to faithfully reproduce the accumulated differential angular Rutherford scattering probability distribution function (pdf) of particles in a plasma. The FAS method splits the scattering events into two regions. At small angles it is described by cumulative scattering events resulting, via the central limit theorem, in a Gaussian-like pdf; at larger angles it is described by single-event scatters and retains a pdf that follows the form of the Rutherford differential cross-section. The FAS method is verified using discrete Monte-Carlo scattering simulations run at small timesteps to include each individual scattering event. We identify the FAS regime of interest as where the ratio of temporal/spatial scale-of-interest to slowing-down time/length is from 10-3 to 0.3-0.7; the upper limit corresponds to Coulomb logarithm of 20-2, respectively. Two test problems, high-velocity interpenetrating plasma flows and keV-temperature ion equilibration, are used to highlight systems where including FAS is important to capture relevant physics.

  6. Determination of ion track and shapes with damage simulations on the base of ellipsometric and backscattering spectrometric measurements

    Energy Technology Data Exchange (ETDEWEB)

    Polgar, O.; Fried, M.; Khanh, N.; Petrik, P.; Barsony, I. [Research Institute for Technical Phisycs and Materials Science, Budapest (Hungary)

    2008-05-15

    On the base of geometrical and statistical considerations a damage simulator was created in order to determine the ion track-radius and -shape of ion-implantation caused damage in single-crystalline Si. Damage vs. dose curves calculated by spectroscopic ellipsometry (SE) and Rutherford backscattering/channeling spectrometry (RBS/C) measurements, using different doses of 100 keV Xe implantation, gave information about the damage profile in depth. Both methods are required, because of dose-dependent discrepancies of SE compared with RBS/C [Fried et al., Thin Solid Films 455/456, 404 (2004)]. Different kinds of damage models were investigated to calculate the ion track-radius and to describe the damages in depth and the shape of ion track. Comparing directly the simulated and the measured damage vs. dose curves, the damage function and the other simulation parameters were optimized and hence the ion track size and even the shape can be determined. The dose dependent mean size of the unchanged crystalline regions, obtained from the simulation was correlated with the complex dielectric functions, obtained from the SE analysis. The results clearly show the effect of decreasing size of the unchanged crystalline regions. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Study on Improvement of Multibeam Backscatter Angular Response Model

    National Research Council Canada - National Science Library

    YAN Jun; ZHANG Hongmei; ZHAO Jianhu; MENG Junxia

    2016-01-01

    Because multibeam backscatter data is greatly affected by the AR (angular response) and the AR correction models are not perfect in the complex seabed, the multibeam image quality is seriously reduced...

  8. Reson 8101 Backscatter imagery of Penguin Bank, Molokai, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery extracted from gridded bathymetry of Penguin Bank, Molokai, Hawaii, USA. These data provide almost complete coverage between 0 and 100 meters....

  9. Backscatter [8101]--Offshore of Monterey Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents 2-m-resolution Reson 8101 data for the acoustic-backscatter map of the Offshore of Monterey map area, California. These metadata...

  10. Backscatter [7125]-- Offshore of Monterey Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents 2-m-resolution Reson 7125 data for the acoustic-backscatter map of Offshore of Monterey map area, California. These metadata describe...

  11. Backscatter [Swath]-- Offshore of Monterey Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents 2-m-resolution SWATHPlus data for the acoustic-backscatter map of Offshore of Monterey map area, California. These metadata describe...

  12. Backscatter B [USGS]--Offshore of Santa Barbara, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3281 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3281) of the Offshore of Santa Barbara map area, California. The...

  13. Backscatter B [USGS]--Offshore of Ventura, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3254 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3254) of the Offshore Ventura map area, California. The raster data...

  14. Backscatter A [CSUMB]--Offshore of Carpinteria, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3261 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3261) of the Offshore of Carpinteria map area, California. The raster...

  15. Backscatter A [CSUMB]--Offshore of Santa Barbara, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3281 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3281) of the Offshore of Santa Barbara map area, California. The...

  16. Photoelectron backscattering from silicon anodes of hybrid photodetector tubes

    CERN Document Server

    D'Ambrosio, C

    2000-01-01

    The impact of photoelectron backscattering on spectral distributions measured with hybrid photodetector tubes has been calculated. The calculations are based on the backscattering coefficient mu , the average number of photoelectrons N/sub phel/ emitted from the photocathode, and on the distribution of the fractional photoelectron energy q absorbed in silicon during the backscattering process. We obtained the following results: the average number of absorbed (measured) photoelectrons N/sub meas/ in the silicon anode amounts to ~88% of the incident N/sub phel/. Photoelectron- and gamma-absorption peaks are broadened by a factor 1.043 due to backscattering. As an example, for photomultiplier tubes, this broadening can amount to an average factor of 1.18 due to statistic and gain fluctuations on the dynode chain. (15 refs).

  17. Bathymetry and Acoustic Backscatter: Northern Santa Barbara Channel, Southern California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This report presents bathymetry and acoustic backscatter data collected in July 2008 in the northern Santa Barbara Channel, California, using a bathymetric sidescan...

  18. Optical Backscattering Measured by Airborne Lidar and Underwater Glider

    Directory of Open Access Journals (Sweden)

    James H. Churnside

    2017-04-01

    Full Text Available The optical backscattering from particles in the ocean is an important quantity that has been measured by remote sensing techniques and in situ instruments. In this paper, we compare estimates of this quantity from airborne lidar with those from an in situ instrument on an underwater glider. Both of these technologies allow much denser sampling of backscatter profiles than traditional ship surveys. We found a moderate correlation (R = 0.28, p < 10−5, with differences that are partially explained by spatial and temporal sampling mismatches, variability in particle composition, and lidar retrieval errors. The data suggest that there are two different regimes with different scattering properties. For backscattering coefficients below about 0.001 m−1, the lidar values were generally greater than the glider values. For larger values, the lidar was generally lower than the glider. Overall, the results are promising and suggest that airborne lidar and gliders provide comparable and complementary information on optical particulate backscattering.

  19. An algorithm to determine backscattering ratio and single scattering albedo

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

    Algorithms to determine the inherent optical properties of water, backscattering probability and single scattering albedo at 490 and 676 nm from the apparent optical property, remote sensing reflectance are presented here. The measured scattering...

  20. Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks.

    Science.gov (United States)

    Lyu, Bin; Yang, Zhen; Gui, Guan; Sari, Hikmet

    2017-06-01

    This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model.

  1. Nanomaterials for Electrochemical Immunosensing.

    Science.gov (United States)

    Pan, Mingfei; Gu, Ying; Yun, Yaguang; Li, Min; Jin, Xincui; Wang, Shuo

    2017-05-05

    Electrochemical immunosensors resulting from a combination of the traditional immunoassay approach with modern biosensors and electrochemical analysis constitute a current research hotspot. They exhibit both the high selectivity characteristics of immunoassays and the high sensitivity of electrochemical analysis, along with other merits such as small volume, convenience, low cost, simple preparation, and real-time on-line detection, and have been widely used in the fields of environmental monitoring, medical clinical trials and food analysis. Notably, the rapid development of nanotechnology and the wide application of nanomaterials have provided new opportunities for the development of high-performance electrochemical immunosensors. Various nanomaterials with different properties can effectively solve issues such as the immobilization of biological recognition molecules, enrichment and concentration of trace analytes, and signal detection and amplification to further enhance the stability and sensitivity of the electrochemical immunoassay procedure. This review introduces the working principles and development of electrochemical immunosensors based on different signals, along with new achievements and progress related to electrochemical immunosensors in various fields. The importance of various types of nanomaterials for improving the performance of electrochemical immunosensor is also reviewed to provide a theoretical basis and guidance for the further development and application of nanomaterials in electrochemical immunosensors.

  2. Lord Rutherford of Nelson, his 1908 Nobel Prize in Chemistry, and why he didn't get a second prize

    Energy Technology Data Exchange (ETDEWEB)

    Jarlskog, Cecilia [Division of Mathematical Physics, LTH, Lund University, Box 118, S-22100 Lund (Sweden)], E-mail: cecilia.jarlskog@matfys.lth.se

    2008-11-01

    'I have dealt with many different transformations with various periods of time, but the quickest that I have met was my own transformation in one moment from a physicist to a chemist.' Ernest Rutherford (Nobel Banquet, 1908) This article is about how Ernest Rutherford (1871-1937) got the 1908 Nobel Prize in Chemistry and why he did not get a second Prize for his subsequent outstanding discoveries in physics, specially the discovery of the atomic nucleus and the proton. Who were those who nominated him and who did he nominate for the Nobel Prizes? In order to put the Prize issue into its proper context, I will briefly describe Rutherford's whereabouts. Rutherford, an exceptionally gifted scientist who revolutionized chemistry and physics, was moulded in the finest classical tradition. What were his opinions on some scientific issues such as Einstein's photon, uncertainty relations and the future prospects for atomic energy? What would he have said about the 'Theory of Everything'? Extended version of an invited talk presented at the conference 'Neutrino 2008', Christchurch, NZ, 25-31 May 2008.

  3. Electrochemical oxidation of cholesterol

    Directory of Open Access Journals (Sweden)

    Jacek W. Morzycki

    2015-03-01

    Full Text Available Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and affords different products depending on the reaction conditions.

  4. Electrochemical cell stack assembly

    Science.gov (United States)

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2010-06-22

    Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

  5. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  6. Use of Local Electrochemical Methods (SECM, EC-STM) and AFM to Differentiate Microstructural Effects (EBSD) on Very Pure Copper

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Lombardia, Esther; Graeve, Iris De; Terryn, Herman [Vrije Universiteit Brussel, Brussels (Belgium); Lapeire, Linsey; Verbeken, Kim; Kestens, Leo [Ghent University, Zwijnaarde (Ghent) (Belgium); Maurice, Vincent; Klein, Lorena; Marcus, Philippe [Institut de Recherche de Chimie Paris, Paris (France); Gonzalez-Garcia, Yaiza; Mol, Arjan [Delft University of Technology, Delft (Netherlands)

    2017-02-15

    When aiming for an increased and more sustainable use of metals a thorough knowledge of the corrosion phenomenon as function of the local metal microstructure is of crucial importance. In this work, we summarize the information presented in our previous publications and present an overview of the different local (electrochemical) techniques that have been proven to be effective in studying the relation between different microstructural variables and their different electrochemical behavior. Atomic force microscopy (AFM), scanning electrochemical microscopy (SECM), and electrochemical scanning tunneling microscopy (EC-STM) were used in combination with electron backscatter diffraction (EBSD). Consequently, correlations could be identified between the grain orientation and grain boundary characteristics, on the one hand, and the electrochemical behavior on the other hand. The grain orientation itself has an influence on the corrosion, and the orientation of the neighboring grains also seems to play a decisive role in the dissolution rate. With respect to intergranular corrosion, only coherent twin boundaries seem to be resistant.

  7. Electrochemical micromachining: An introduction

    Directory of Open Access Journals (Sweden)

    Rebecca J Leese

    2016-01-01

    Full Text Available Electrochemical machining is a relatively new technique, only being introduced as a commercial technique within the last 70 years. A lot of research was conducted in the 1960s and 1970s, but research on electrical discharge machining around the same time slowed electrochemical machining research. The main influence for the development of electrochemical machining came from the aerospace industry where very hard alloys were required to be machined without leaving a defective layer in order to produce a component which would behave reliably. Electrochemical machining was primarily used for the production of gas turbine blades or to machine materials into complex shapes that would be difficult to machine using conventional machining methods. Tool wear is high and the metal removal rate is slow when machining hard materials with conventional machining methods such as milling. This increases the cost of the machining process overall and this method creates a defective layer on the machined surface. Whereas with electrochemical machining there is virtually no tool wear even when machining hard materials and it does not leave a defective layer on the machined surface. This article reviews the application of electrochemical machining with regards to micro manufacturing and the present state of the art micro electrochemical machining considering different machined materials, electrolytes and conditions used.

  8. Electrochemical force microscopy

    Science.gov (United States)

    Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

    2017-01-10

    A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

  9. Study on Improvement of Multibeam Backscatter Angular Response Model

    Directory of Open Access Journals (Sweden)

    YAN Jun

    2016-11-01

    Full Text Available Because multibeam backscatter data is greatly affected by the AR (angular response and the AR correction models are not perfect in the complex seabed, the multibeam image quality is seriously reduced. This paper puts forward an improved AR model and a correction method. Firstly, we average continual pings to obtain the AR curve; Secondly, we give out the extraction method of AR parameters; Thirdly, we use the parameters to establish the improved AR model of different sections of one ping; Finally, we use the model to weaken the AR effect in multibeam backscatter images. The validities of the method have been verified by the experiments of the field multibeam acoustic backscatter.

  10. Development of the Nb3Sn Rutherford Cable for the EuCARD High Field Dipole Magnet FRESCA2

    CERN Document Server

    Oberli, l

    2013-01-01

    This paper reports on the development of the Nb3Sn Rutherford cable for the EuCARD high field dipole magnet FRESCA2 designed to achieve a central field of 13 T at 4.2 K in a 100 mm bore. The FRESCA2 cable is rectangular and made of 40 strands of 1.0 mm diameter. The cable shall be able to carry a current of 15.7 kA at 4.2 K in a field of 15 T. In the first stage of cable development, focus was put on the cable parameters (cable width, cable mid-thickness and pitch length) to provide a cable made with Nb3Sn PIT strands achieving both a minimal critical current reduction of the strand during cabling and a good mechanical stability of the cable for coil winding. In the second stage of cable development, the cable was produced with Nb3Sn RRP strands. The cables, which were produced following an iterative process, were characterized and the results of the critical current measurements of extracted strands are discussed together with the cabling parameters and the type of strand.

  11. Fundamentals of electrochemical science

    CERN Document Server

    Oldham, Keith

    1993-01-01

    Key Features* Deals comprehensively with the basic science of electrochemistry* Treats electrochemistry as a discipline in its own right and not as a branch of physical or analytical chemistry* Provides a thorough and quantitative description of electrochemical fundamentals

  12. Electrochemical Analysis of Neurotransmitters

    Science.gov (United States)

    Bucher, Elizabeth S.; Wightman, R. Mark

    2015-07-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

  13. Effect of curvature on the backscattering from a leaf

    Science.gov (United States)

    Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

    1988-01-01

    Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross-section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

  14. Effect of curvature on the backscattering from leaves

    Science.gov (United States)

    Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

    1988-01-01

    Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

  15. Enhanced compton backscattering by confocal multipath laser cavity

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu [Himeji Institute of Technology, Laboratory of Advanced Science Technology for Industry, Kamigori, Hyogo (Japan)

    2001-10-01

    The design considerations of a confocal multipath laser cavity to enhance Compton backscattering are presented. Laser pulses are superposed at a confocal point of the cavity and enhance laser peak filed there. Ray trace simulation results predicted that the 29 - 14-fold enhanced laser filed could be achieved with the mode locked laser pulses whose repetition rate and duration time were 89.25 MHz and 10 ps, respectively. As a result, Compton backscattered X-rays generated by interaction of this intense laser field with a relativistic electron beam, will be enhanced efficiently by a factor of more than 10 at least. (author)

  16. Ultrasonic backscatter from elongated grains using line focused ultrasound.

    Science.gov (United States)

    Kube, Christopher M; Arguelles, Andrea P; Turner, Joseph A

    2018-01-01

    Ultrasonic backscattering from polycrystalline materials with elongated grains is investigated. A normal incident line-focus transducer is employed such that refracted longitudinal and transverse waves are focused within the polycrystal and scatter at grain boundaries back to the transducer. A ray-based scattering model is developed to explain the dependence of the statistics of scattering measurements on grain elongation. The spatial variance of measured scattered signals from Al alloy (7475-T7) is compared to the model. This work promotes the ultrasonic backscatter technique for monitoring grain elongation of metals using one transducer with access to a single sample face. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Ultrasound attenuation estimation using backscattered echoes from multiple sources

    OpenAIRE

    Bigelow, Timothy A.

    2008-01-01

    The objective of this study was to devise an algorithm that can accurately estimate the attenuation along the propagation path (i.e., the total attenuation) from backscattered echoes. It was shown that the downshift in the center frequency of the backscattered ultrasound echoes compared to echoes obtained in a water bath was calculated to have the form Δf=mfo+b after normalizing with respect to the source bandwidth where m depends on the correlation length, b depends on the total attenuation,...

  18. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  19. Solid state electrochemical composite

    Science.gov (United States)

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2009-06-30

    Provided is a composite electrochemical device fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems including oxygen generation system.

  20. Analysis of the quench propagation along Nb3Sn Rutherford cables with the THELMA code. Part II: application to the quench longitudinal propagation

    CERN Document Server

    Manfreda, G.; Bajas, H.; Perez, J.C.

    2016-01-01

    To improve the technology of the new generation of accelerator magnets, prototypes are being manufactured and tested in several laboratories. In parallel, many numerical analyses are being carried out to predict the magnets behaviour and interpret the experimental results. This paper focuses on the quench propagation velocity, which is a crucial parameter as regards the energy dissipation along the magnet conductor. The THELMA code, originally developed for cable-in-conduit conductors for fusion magnets, has been used to study such quench propagation. To this purpose, new code modules have been added to describe the Rutherford cable geometry, the material non-linear thermal properties and to describe the thermal conduction problem in transient regime. THELMA can describe the Rutherford cable at the strand level, modelling both the electrical and thermal contact resistances between strands and enabling the analysis of the effects of local hot spots and quench heaters. This paper describes the model application...

  1. Optical backscattering properties of the "clearest" natural waters

    Directory of Open Access Journals (Sweden)

    M. S. Twardowski

    2007-11-01

    Full Text Available During the BIOSOPE field campaign October–December 2004, measurements of inherent optical properties from the surface to 500 m depth were made with a ship profiler at stations covering over 8000 km through the Southeast Pacific Ocean. Data from a ~3000 km section containing the very clearest waters in the central gyre are reported here. The total volume scattering function at 117°, βt(117°, was measured with a WET Labs ECO-BB3 sensor at 462, 532, and 650 nm with estimated uncertainties of 2×10-5, 5×10-6, and 2×10-6 m−1 sr−1, respectively. These values were approximately 6%, 3%, and 3% of the volume scattering by pure seawater at their respective wavelengths. From a methodological perspective, there were several results:

    – distributions were resolvable even though some of the values from the central gyre were an order of magnitude lower than the lowest previous measurements in the literature;
    – Direct in-situ measurements of instrument dark offsets were necessary to accurately resolve backscattering at these low levels;
    – accurate pure seawater backscattering values are critical in determining particulate backscattering coefficients in the open ocean (not only in these very clear waters; the pure water scattering values determined by Buiteveld et al. (1994 with a [1+0.3S/37] adjustment for salinity based on Morel (1974 appear to be the most accurate estimates, with aggregate accuracies as low as a few percent; and
    – closure was demonstrated with subsurface reflectance measurements reported by Morel et al. (2007 within instrument precisions, a useful factor in validating the backscattering measurements.

    This methodology enabled several observations with respect to the hydrography and the use of backscattering as a biogeochemical proxy:

    –The clearest waters sampled were found at depths between 300 and 350 m, from 23.5° S

  2. Angioplastia infra-inguinal em pacientes com isquemia crítica grau III, categoria 5 de Rutherford Infra-inguinal angioplasty in patients with critical limb ischemia Rutherford grade III, category 5

    Directory of Open Access Journals (Sweden)

    Abdo Farret Neto

    2008-06-01

    Full Text Available OBJETIVO: Analisar a eficiência da angioplastia primária infra-inguinal como método de salvamento de membros em pacientes portadores de lesões tróficas por isquemia crítica. MATERIAIS E MÉTODOS: Foram analisados 36 pacientes submetidos a angioplastias primárias sem stent. Todos os pacientes apresentavam isquemia crítica com lesão trófica - grau III, categoria 5 de Rutherford -, sendo 17 lesões na artéria femoral superficial, 16 na artéria poplítea e 51 em artérias da perna, totalizando 84 angioplastias. Foram analisadas também as prevalências em relação a sexo, membro afetado, idade e principais comorbidades, sendo tecidas considerações técnicas sobre os procedimentos, assim como os materiais utilizados. RESULTADOS: Considerou-se sucesso quando a lesão trófica que motivou a angioplastia cicatrizou, ou o nível de amputação limitou-se a artelhos ou ao antepé, sem ter havido necessidade de procedimento cirúrgico de reconstituição do fluxo sanguíneo (bypass, independentemente de tempo, drogas associadas e números de desbridamentos realizados. CONCLUSÃO: As angioplastias no segmento femoropoplíteo e infrapoplíteo são procedimentos de elevado sucesso técnico, baixa morbidade e mortalidade, constituindo-se procedimento eficaz em pacientes com isquemia crítica de membro inferior.OBJECTIVE: To evaluate the efficacy of infra-inguinal, primary angioplasty as a method of limb salvage in patients with trophic lesions secondary to critical ischemia. MATERIALS AND METHODS: Thirty-six patients submitted to primary percutaneous transluminal angioplasty without stenting were evaluated. All of them presented critical limb ischemia with trophic lesion (Rutherford grade III, category 5. Eighty-four angioplasties were performed for 17 lesions in superficial femoral artery, 16 lesions in popliteal artery, and 51 lesions in below-knee arteries. Additionally, prevalence in relation to sex, age, limb involved and main comorbidities

  3. Formation of Nanoporous Gold Studied by Transmission Electron Backscatter Diffraction

    NARCIS (Netherlands)

    de Jeer, Leo T. H.; Gomes, Diego Ribas; Nijholt, Jorrit E.; van Bremen, Rik; Ocelik, Vaclav; De Hosson, Jeff Th. M.

    2015-01-01

    Transmission electron backscatter diffraction (t-EBSD) was used to investigate the effect of dealloying on the microstructure of 140-nm thin gold foils. Statistical and local comparisons of the microstructure between the nonetched and nanoporous gold foils were made. Analyses of crystallographic

  4. Method and Apparatus for Computed Imaging Backscatter Radiography

    Science.gov (United States)

    Shedlock, Daniel (Inventor); Meng, Christopher (Inventor); Sabri, Nissia (Inventor); Dugan, Edward T. (Inventor); Jacobs, Alan M. (Inventor)

    2013-01-01

    Systems and methods of x-ray backscatter radiography are provided. A single-sided, non-destructive imaging technique utilizing x-ray radiation to image subsurface features is disclosed, capable of scanning a region using a fan beam aperture and gathering data using rotational motion.

  5. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    a new interest has grown in recent years as its properties have become important in electron beam lithography [8] and scanning electron microscopy (SEM) [9]. Ob- servable properties of backscattered electrons (BEs) consist of their absolute yield per incident electron (the BE coefficient η), their angular and energy ...

  6. Backscatter A [CSUMB]--Offshore Coal Oil Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3302 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3302) of the Offshore of Coal Oil Point map area, California. The...

  7. Fine Scale Measurements of Microwave Backscatter from the Ocean Surface

    Science.gov (United States)

    1993-05-13

    Radar ( SAR ) but would form the image so rapidly that distortion due to ocean surface motion would be essentially eliminated. Following discussions...swells present throughout the day. Figure 7 is a backscatter intensity image made at a range of 300-400 m. This image was despeckled by averaging

  8. The Growth and Decay of Equatorial Backscatter Plumes.

    Science.gov (United States)

    1980-02-01

    spatially connected to bottomside backscatter, a feature noted in Jica- marca radar observations that led Woodman and La Hoz (1976) to speculate that...described in Section Ill-B, this pattern of plume growth resembles the "C-shaped" and "fishtail" patterns found in Jica- marca radar RTI displays of 50-MHz

  9. Lattice constant measurement from electron backscatter diffraction patterns

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.

    2017-01-01

    Kikuchi bands in election backscattered diffraction patterns (EBSP) contain information about lattice constants of crystallographic samples that can be extracted via the Bragg equation. An advantage of lattice constant measurement from EBSPs over diffraction (XRD) is the ability to perform local ...

  10. Ultrasonic Characterization of Tissues via Backscatter Frequency Dependence

    DEFF Research Database (Denmark)

    Stetson, Paul F.; Sommer, F.G.

    1997-01-01

    Phantom and patient studies were performed to assess the potential of backscatter frequency dependence as a useful parameter for tissue characterization. A commercial phased-array ultrasonic scanner was adapted to allow digitization of the intermediate-frequency ultrasonic data, Studies of agar...

  11. Backscatter C [Fugro]--Offshore of Coal Oil Point, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3302 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3302) of the Offshore of Coal Oil Point map area, California. The...

  12. Impact of diurnal variation in vegetation water content on radar backscatter from maize during water stress

    NARCIS (Netherlands)

    Van Emmerik, T.H.M.; Dunne, S.C.; Judge, J.; van de Giesen, N.C.

    2014-01-01

    Microwave backscatter from vegetated surfaces is influenced by vegetation structure and vegetation water content (VWC), which varies with meteorological conditions and moisture in the root zone. Radar backscatter observations are used for many vegetation and soil moisture monitoring applications

  13. BackscatterA [USGS SWATH]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  14. BackscatterD [CSUMB Swath]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  15. Multibeam Backscatter Data for Selected U.S. Locations in the Pacific

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry for selected U.S. locations in the Pacific. The backscatter datasets include data collected using the...

  16. BackscatterC [7125]--Offshore of Salt Point Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Salt Point map area, California. Backscatter data are provided as separate...

  17. Acoustic backscatter from 2013 interferometric swath bathymetry systems survey of Columbia River Mouth, Oregon and Washington

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the USGS data release presents acoustic backscatter data for the Columbia River Mouth, Oregon and Washington. The acoustic backscatter data of the...

  18. BackscatterA [8210]--Offshore of Salt Point Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Salt Point map area, California. Backscatter data are provided as separate...

  19. BackscatterA [8101]--Offshore of Point Reyes Map Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Point Reyes map area, California. Backscatter data are provided as separate...

  20. BackscatterB [Swath]--Offshore of Point Reyes Map Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Point Reyes map area, California. Backscatter data are provided as separate...

  1. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen

    2015-08-19

    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  2. Differential scattering cross-sections, inelastic energy losses and ion fractions in backscattering of keV He sup + ions from monolayer metal adsorbates on solid surfaces measured by means of CAICISS

    CERN Document Server

    Kishi, N

    2002-01-01

    Energy spectra of He atoms and He sup + ions backscattered at an angle of approx 180 deg. by monolayer metal adsorbates (Ag, Sn, Sb, Pb and Bi) on the Si(1 1 1)-sq root 3x sq root 3 surfaces and monolayer Si atoms on the graphite surface have been measured by means of the coaxial impact collision ion scattering spectroscopy technique combined with low energy electron diffraction, Auger electron spectroscopy and Rutherford backscattering spectrometry techniques in the energy range from 0.5 to 3.0 keV. It is found from their data analysis that the ratios of the experimental scattering cross-section to the magic formula of the Thomas-Fermi cross-section for different adsorbates deviate from unity: for instance 1.2 for Si, 0.8 for Ag, 1.5 for Sn, 1.2 for Sb, 1.2 for Pb and 1.6 for Bi. It is also found that the average inelastic energy loss for Si increases monotonically with increasing the incident energy, while those for the other adsorbates increase stepwisely at around 1.0 keV and thereafter gradually. Moreove...

  3. Drivers of ASCAT C band backscatter variability in the dry snow zone of Antarctica

    NARCIS (Netherlands)

    Fraser, Alexander D.; Nigro, Melissa A.; Ligtenberg, Stefan R. M.; Legresy, Benoit; Inoue, Mana; Cassano, John J.; Munneke, Peter Kuipers; Lenaerts, Jan T. M.; Young, Neal W.; Treverrow, Adam; Van Den Broeke, Michiel; Enomot, Hiroyuki

    2016-01-01

    C band backscatter parameters contain information about the upper snowpack/firn in the dry snow zone. The wide incidence angle diversity of the Advanced Scatterometer (ASCAT) gives unprecedented characterisation of backscatter anisotropy, revealing the backscatter response to climatic forcing. The A

  4. Electrochemical energy storage

    CERN Document Server

    Tarascon, Jean-Marie

    2015-01-01

    The electrochemical storage of energy has become essential in assisting the development of electrical transport and use of renewable energies. French researchers have played a key role in this domain but Asia is currently the market leader. Not wanting to see history repeat itself, France created the research network on electrochemical energy storage (RS2E) in 2011. This book discusses the launch of RS2E, its stakeholders, objectives, and integrated structure that assures a continuum between basic research, technological research and industries. Here, the authors will cover the technological

  5. Electrochemical nitridation of metal surfaces

    Science.gov (United States)

    Wang, Heli; Turner, John A.

    2015-06-30

    Electrochemical nitridation of metals and the produced metals are disclosed. An exemplary method of electrochemical nitridation of metals comprises providing an electrochemical solution at low temperature. The method also comprises providing a three-electrode potentiostat system. The method also comprises stabilizing the three-electrode potentiostat system at open circuit potential. The method also comprises applying a cathodic potential to a metal.

  6. Rutherford and Bohr*

    Indian Academy of Sciences (India)

    IAS Admin

    language. He had a loud and booming voice, and it is said that in the days when counting circuits tended to be sensitive to noise, the performance of his collaborators' equipment went wrong whenever he entered their research rooms. He made decisions easily and firmly, and once a matter was decided, did not give it any ...

  7. Retrieval of Ocean Subsurface Particulate Backscattering Coefficient from Space-Borne CALIOP Lidar Measurement

    Science.gov (United States)

    Lu, Xiaomei; Hu, Yongxiang; Pelon, Jacques; Trepte, Chip; Liu, Katie; Rodier, Sharon; Zeng, Shan; Luckher, Patricia; Verhappen, Ron; Wilson, Jamie; hide

    2016-01-01

    A new approach has been proposed to determine ocean subsurface particulate backscattering coefficient bbp from CALIOP 30deg off-nadir lidar measurements. The new method also provides estimates of the particle volume scattering function at the 180deg scattering angle. The CALIOP based layer-integrated lidar backscatter and particulate backscattering coefficients are compared with the results obtained from MODIS ocean color measurements. The comparison analysis shows that ocean subsurface lidar backscatter and particulate backscattering coefficient bbp can be accurately obtained from CALIOP lidar measurements, thereby supporting the use of space-borne lidar measurements for ocean subsurface studies.

  8. Retrieval of ocean subsurface particulate backscattering coefficient from space-borne CALIOP lidar measurements.

    Science.gov (United States)

    Lu, Xiaomei; Hu, Yongxiang; Pelon, Jacques; Trepte, Charles; Liu, Katie; Rodier, Sharon; Zeng, Shan; Lucker, Patricia; Verhappen, Ron; Wilson, Jamie; Audouy, Claude; Ferrier, Christophe; Haouchine, Said; Hunt, Bill; Getzewich, Brian

    2016-12-12

    A new approach has been proposed to determine ocean subsurface particulate backscattering coefficient bbp from CALIOP 30° off-nadir lidar measurements. The new method also provides estimates of the particle volume scattering function at the 180° scattering angle. The CALIOP based layer-integrated lidar backscatter and particulate backscattering coefficients are compared with the results obtained from MODIS ocean color measurements. The comparison analysis shows that ocean subsurface lidar backscatter and particulate backscattering coefficient bbp can be accurately obtained from CALIOP lidar measurements, thereby supporting the use of space-borne lidar measurements for ocean subsurface studies.

  9. Lidar extinction-to-backscatter ratio of the ocean.

    Science.gov (United States)

    Churnside, James H; Sullivan, James M; Twardowski, Michael S

    2014-07-28

    Bio-optical models are used to develop a model of the lidar extinction-to-backscatter ratio applicable to oceanographic lidar. The model is based on chlorophyll concentration, and is expected to be valid for Case 1 waters. The limiting cases of narrow- and wide-beam lidars are presented and compared with estimates based on in situ optical measurements. Lidar measurements are also compared with the model using in situ or satellite estimates of chlorophyll concentration. A modified lidar ratio is defined, in which the properties of pure sea water are removed. This modified ratio is shown to be nearly constant for wide-beam lidar operating in low-chlorophyll waters, so accurate inversion to derive extinction and backscattering is possible under these conditions. This ratio can also be used for lidar calibration.

  10. Present State of Electron Backscatter Diffraction and Prospective Developments

    Energy Technology Data Exchange (ETDEWEB)

    Schwarzer, R A; Field, D P; Adams, B L; Kumar, M; Schwartz, A J

    2008-10-24

    Electron backscatter diffraction (EBSD), when employed as an additional characterization technique to a scanning electron microscope (SEM), enables individual grain orientations, local texture, point-to-point orientation correlations, and phase identification and distributions to be determined routinely on the surfaces of bulk polycrystals. The application has experienced rapid acceptance in metallurgical, materials, and geophysical laboratories within the past decade (Schwartz et al. 2000) due to the wide availability of SEMs, the ease of sample preparation from the bulk, the high speed of data acquisition, and the access to complementary information about the microstructure on a submicron scale. From the same specimen area, surface structure and morphology of the microstructure are characterized in great detail by the relief and orientation contrast in secondary and backscatter electron images, element distributions are accessed by energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), or cathodoluminescence analysis, and the orientations of single grains and phases can now be determined, as a complement, by EBSD.

  11. Bathymetry and acoustic backscatter: Elwha River Delta, Washington

    Science.gov (United States)

    Finlayson, David P.; Miller, Ian M.; Warrick, Jonathan A.

    2011-01-01

    Between February 22 and March 3, 2010, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from the Elwha River Delta, Strait of Juan de Fuca, Washington, under PCMSC Field Activity ID S-6-10-PS. Three ancillary surveys were conducted when sea conditions were too rough for surveying outside the harbor breakwaters. The first ancillary survey was of the area surrounding the abandoned Rayonier Pier site in Port Angeles Harbor, a former log-storage facility on the southern side of Ediz Hook near the Port Angeles Coast Guard Station. Finally, several lines of bathymetry and backscatter data were collected on the outer face of Ediz Hook as the vessel transited to and from the Elwha River Delta. These data were collected to inspect failure features along the northern edge of Ediz Hook that were first observed in 2005 during USGS cruise K-1-05-PS.

  12. RFID tag modification for full depth backscatter modulation

    Science.gov (United States)

    Scott, Jeffrey Wayne [Pasco, WA; Pratt, Richard M [Richland, WA

    2010-07-20

    A modulated backscatter radio frequency identification device includes a diode detector configured to selectively modulate a reply signal onto an incoming continuous wave; communications circuitry configured to provide a modulation control signal to the diode detector, the diode detector being configured to modulate the reply signal in response to be modulation control signal; and circuitry configured to increase impedance change at the diode detector which would otherwise not occur because the diode detector rectifies the incoming continuous wave while modulating the reply signal, whereby reducing the rectified signal increases modulation depth by removing the reverse bias effects on impedance changes. Methods of improving depth of modulation in a modulated backscatter radio frequency identification device are also provided.

  13. Electrochemical Power Sources

    Indian Academy of Sciences (India)

    Motor-vehicle industry is presently pursuing technologies capable of eliminating emissions with higher fuel-efficien- cies. Fuel cells and more recently, electrochemical supercapacitors have been found to be attractive options for electric vehicles. Fuel cells convert the chemical energy of a fuel directly into dc electricity with ...

  14. Electrochemical Power Sources

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 7. Electrochemical Power Sources - Rechargeable Batteries. A K Shukla S K Martha. General Article Volume 6 Issue 7 July 2001 pp 52-63. Fulltext. Click here to view fulltext PDF. Permanent link:

  15. Electrochemical micro actuator

    NARCIS (Netherlands)

    Hamberg, M.W.; Hamberg, M.W.; Rusu, C.R.; Gardeniers, Johannes G.E.; Ijntema, D.J.; IJntema, D.J.; Elwenspoek, Michael Curt

    1995-01-01

    In this paper an investigation of the feasibility of a new electrochemical micro actuator is presented. The actuator is fabricated using silicon micro-machining techniques. A gas pressure is generated by electrolysis of an aqueous electrolyte solution. The build up pressure is used to change the

  16. ELECTROCHEMICAL BEHAVIOUR AND VOLTAMMETRIC ...

    African Journals Online (AJOL)

    The electrochemical behaviour of Geshoidin was investigated at a glassy carbon electrode in mixtures of citric acid and di-sodium hydrogen orthophosphate aqueous buffer system over a wide pH range (pH 2-11) using cyclic voltammetry. Chemically irreversible single oxidation and reduction peaks were obtained in the ...

  17. High Power Electrochemical Capacitors

    Science.gov (United States)

    2012-03-23

    and Cu surfaces using trimethylamine alane (TMAA) as an organometallic CVD precursor. For this project we further demonstrated that the ALD deposition...this work, we show how the application of nanodiamond (ND) can greatly increase the performance of electrochemically active polymers , such as

  18. Multiple scattering wavelength dependent backscattering of kaolin dust in the IR: Measurements and theory

    Science.gov (United States)

    Ben-David, Avishai

    1992-01-01

    Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.

  19. Ion beam polishing for three-dimensional electron backscattered diffraction

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Ubhi, H.S.

    2013-01-01

    Serial sectioning by focused ion beam milling for three-dimensional electron backscatter diffraction (3D-EBSD) can create surface damage and amorphization in certain materials and consequently reduce the EBSD signal quality. Poor EBSD signal causes longer data acquisition time due to signal avera.......3% of normal 3D-EBSD mapping compared to a significant increase of indexing percentage and pattern quality. The polishing performance in this investigation is discussed, and two potential methods for further improvement are presented....

  20. Myocardial ultrasonic backscatter in hypertension: relation to aldosterone and endothelin.

    Science.gov (United States)

    Kozàkovà, Michaela; Buralli, Simona; Palombo, Carlo; Bernini, Giampaolo; Moretti, Angelica; Favilla, Stefania; Taddei, Stefano; Salvetti, Antonio

    2003-02-01

    A disproportionate accumulation of fibrillar collagen is a characteristic feature of hypertensive heart disease, but the extent of myocardial fibrosis may differ in different models of hypertension. In experimental studies, aldosterone and endothelins emerge as important determinants of myocardial fibrosis. Changes in myocardial extracellular matrix and collagen deposition can be estimated noninvasively by analysis of the ultrasonic backscatter signal, which arises from tissue heterogeneity within the myocardium and describes myocardial texture. This study was designed to investigate the relations between myocardial integrated backscatter and circulating aldosterone and immunoreactive endothelin in human hypertension. The study population consisted of 56 subjects: 14 healthy normotensive volunteers and 42 hypertensive patients (14 with primary aldosteronism, 7 with renovascular hypertension, and 21 with essential hypertension). The patients with essential and secondary hypertension were matched for age, gender, body mass index, and blood pressure. Myocardial integrated backscatter at diastole was 19.8+/-2.0 and 20.8+/-2.9 decibels in normotensive control subjects and patients with essential hypertension and significantly higher in patients with primary aldosteronism (27.4+/-3.8 decibels, P<0.01) and renovascular hypertension (26.8+/-4.8 decibels, P<0.01). In the population as a whole, as well as in the hypertensive subpopulation, myocardial integrated backscatter was directly related to plasma aldosterone (r=0.73 and 0.71, P<0.01 for both) and immunoreactive endothelin (r=0.60 and 0.56, P<0.01 for both). The data of this study suggest that in human hypertension, circulating aldosterone and immunoreactive endothelin may induce alterations in left ventricular myocardial texture, possibly related to increased myocardial collagen content.

  1. Electrochemical systems configured to harvest heat energy

    Science.gov (United States)

    Lee, Seok Woo; Yang, Yuan; Ghasemi, Hadi; Chen, Gang; Cui, Yi

    2017-01-31

    Electrochemical systems for harvesting heat energy, and associated electrochemical cells and methods, are generally described. The electrochemical cells can be configured, in certain cases, such that at least a portion of the regeneration of the first electrochemically active material is driven by a change in temperature of the electrochemical cell. The electrochemical cells can be configured to include a first electrochemically active material and a second electrochemically active material, and, in some cases, the absolute value of the difference between the first thermogalvanic coefficient of the first electrochemically active material and the second thermogalvanic coefficient of the second electrochemically active material is at least about 0.5 millivolts/Kelvin.

  2. Lidar Inversion of Atmospheric Backscatter and Extinction-To-Backscatter Ratios by Use of a Kalman Filter

    Science.gov (United States)

    Rocadenbosch, Francesc; Soriano, Cecilia; Comerón, Adolfo; Baldasano, José-María

    1999-05-01

    A first inversion of the backscatter profile and extinction-to-backscatter ratio from pulsed elastic-backscatter lidar returns is treated by means of an extended Kalman filter (EKF). The EKF approach enables one to overcome the intrinsic limitations of standard straightforward nonmemory procedures such as the slope method, exponential curve fitting, and the backward inversion algorithm. Whereas those procedures are inherently not adaptable because independent inversions are performed for each return signal and neither the statistics of the signals nor a priori uncertainties (e.g., boundary calibrations) are taken into account, in the case of the Kalman filter the filter updates itself because it is weighted by the imbalance between the a priori estimates of the optical parameters (i.e., past inversions) and the new estimates based on a minimum-variance criterion, as long as there are different lidar returns. Calibration errors and initialization uncertainties can be assimilated also. The study begins with the formulation of the inversion problem and an appropriate atmospheric stochastic model. Based on extensive simulation and realistic conditions, it is shown that the EKF approach enables one to retrieve the optical parameters as time-range-dependent functions and hence to track the atmospheric evolution; the performance of this approach is limited only by the quality and availability of the a priori information and the accuracy of the atmospheric model used. The study ends with an encouraging practical inversion of a live scene measured at the Nd:YAG elastic-backscatter lidar station at our premises at the Polytechnic University of Catalonia, Barcelona.

  3. System level electrochemical principles

    Science.gov (United States)

    Thaller, L. H.

    1985-07-01

    The traditional electrochemical storage concepts are difficult to translate into high power, high voltage multikilowatt storage systems. The increased use of electronics, and the use of electrochemical couples that minimize the difficulties associated with the corrective measures to reduce the cell to cell capacity dispersion were adopted by battery technology. Actively cooled bipolar concepts are described which represent some attractive alternative system concepts. They are projected to have higher energy densities lower volumes than current concepts. They should be easier to scale from one capacity to another and have a closer cell to cell capacity balance. These newer storage system concepts are easier to manage since they are designed to be a fully integrated battery. These ideas are referred to as system level electrochemistry. The hydrogen-oxygen regenerative fuel cells (RFC) is probably the best example of the integrated use of these principles.

  4. Electrochemical nanomoulding through proteins

    Science.gov (United States)

    Allred, Daniel B.

    The continued improvements in performance of modern electronic devices are directly related to the manufacturing of smaller, denser features on surfaces. Electrochemical fabrication has played a large role in continuing this trend due to its low cost and ease of scaleability toward ever smaller dimensions. This work introduces the concept of using proteins, essentially monodisperse complex polymers whose three-dimensional structures are fixed by their encoded amino acid sequences, as "moulds" around which nanostructures can be built by electrochemical fabrication. Bacterial cell-surface layer proteins, or "S-layer" proteins, from two organisms---Deinococcus radiodurans and Sporosarcina ureae---were used as the "moulds" for electrochemical fabrication. The proteins are easily purified as micron-sized sheets of periodic molecular complexes with 18-nm hexagonal and 13-nm square unit cell lattices, respectively. Direct imaging by transmission electron microscopy on ultrathin noble metal films without sample preparation eliminates potential artifacts to the high surface energy substrates necessary for high nucleation densities. Characterization involved imaging, electron diffraction, spectroscopy, and three-dimensional reconstruction. The S-layer protein of D. radiodurans was further subjected to an atomic force microscope based assay to determine the integrity of its structure and long-range order and was found to be useful for fabrication from around pH 3 to 12.

  5. ELECTROCHEMICAL POWER FOR TRANSPORTATION

    Energy Technology Data Exchange (ETDEWEB)

    Cairns, Elton J.; Hietbrink, Earl H.

    1981-01-01

    This section includes some historical background of the rise and fall and subsequent rebirth of the electric vehicle; and a brief discussion of current transportation needs, and environmental and energy utilization issues that resulted in the renewed interest in applying electrochemical energy conversion technology to electric vehicle applications. Although energy utilization has evolved to be the most significant and important issue, the environmental issue will be discussed first in this section only because of its chronological occurrence. The next part of the chapter is a review of passenger and commercial electric vehicle technology with emphasis on vehicle design and demonstrated performance of vehicles with candidate power sources being developed. This is followed by a discussion of electrochemical power source requirements associated with future electric vehicles that can play a role in meeting modern transportation needs. The last part of the chapter includes first a discussion of how to identify candidate electrochemical systems that might be of interest in meeting electric vehicle power source requirements. This is then followed by a review of the current technological status of these systems and a discussion of the most significant problems that must be resolved before each candidate system can be a viable power source.

  6. Rutherford cable made of internal magnesium diffusion MgB2 wires sheathed with Al-Al2O3 particulate metal matrix composite

    Science.gov (United States)

    Kováč, P.; Kopera, L.; Kováč, J.; Hain, M.; Melišek, T.; Kulich, M.; Hušek, I.

    2018-01-01

    Rutherford MgB2 cable has been made from 12 single-core wires prepared via the internal magnesium diffusion process with a light outer sheath of Al-Al2O3 particulate metal matrix composite. Initially, critical currents of single-core wires with different diameters (between 1 mm and 0.465 mm) were measured. X-ray tomography was applied for the analysis of the uniformity of a Rutherford cable assembled of 0.465 mm strands. The obtained engineering current density at 4.2 K and 6. 5 T for the present cable (with only 9.6% of MgB2) is ∼3.6 times higher in comparison with a similar cable fabricated via the powder-in-tube in situ process with 19.8% of MgB2 phase. The strain tolerance of the cable by bending has shown a critical diameter of 70 mm. AC losses measured via the calibration-free method have shown apparently lower coupling losses for the cabled conductor. The obtained results are promising for future lightweight, mechanically flexible and low AC loss MgB2 superconductors suitable especially for motors or generators.

  7. Estimation of Mars radar backscatter from measured surface rock populations

    Science.gov (United States)

    Baron, J.E.; Simpson, R.A.; Tyler, G.L.; Moore, H.J.; Harmon, J.K.

    1998-01-01

    Reanalysis of rock population data at the Mars Viking Lander sites has yielded updated values of rock fractional surface coverage (about 0.16 at both sites, including outcrops) and new estimates of rock burial depths and axial ratios. These data are combined with a finite difference time domain (FDTD) numerical scattering model to estimate diffuse backscatter due to rocks at both the Lander l (VL1) and Lander 2 (VL2) sites. We consider single scattering from both surface and subsurface objects of various shapes, ranging from an ideal sphere to an accurate digitized model of a terrestrial rock. The FDTD cross-section calculations explicitly account for the size, shape, composition, orientation, and burial state of the scattering object, the incident wave angle and polarization, and the composition of the surface. We calculate depolarized specific cross sections at 12.6 cm wavelength due to lossless rock-like scatterers of about 0.014 at VL1 and 0.023 at VL2, which are comparable to the measured ranges of 0.019-0.032 and 0.012-0.018, respectively. We also discuss the variation of the diffuse cross section as the local angle of incidence, ??i, changes. Numerical calculations for a limited set of rock shapes indicate a marked difference between the angular backscattering behavior of wavelength-scale surface and subsurface rocks: while subsurface rocks scatter approximately as a cosine power law, surface rocks display a complex variation, often with peak backscattering at high incidence angles (??i = 70??-75??). Copyright 1998 by the American Geophysical Union.

  8. Quantifying Fish Backscattering using SONAR Instrument and Kirchhoff Ray Mode (KRM) Model

    Science.gov (United States)

    Manik, Henry M.

    2016-08-01

    Sonar instrument was used to study backscattering from tuna fish. Extraction of target strength, incidence angle, and frequency dependence of the backscattered signal for individual scatterer was important for biological information. For this purpose, acoustic measurement of fish backscatter was conducted in the laboratory. Characteristics and general trends of the target strength of fish with special reference to tuna fish were investigated by using a Kirchhoff Ray Mode (KRM) model. Backscattering strength were calculated for the KRM having typical morphological and physical parameters of actual fish. Those backscattering amplitudes were shown as frequency, body length, backscattering patterns, the density and sound speed dependences, and orientation dependence. These results were compared with experimentally measured target strength data and good agreement was found. Measurement and model showed the target strength from the fish are depend on the presence of swimbladder. Target Strength increase with increasing the frequency and fish length.

  9. Lensless imaging based on coherent backscattering in random media

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2014-08-01

    Full Text Available We studied lensless imaging due to coherent backscattering in random media both theoretically and experimentally. The point spread function of the lensless imaging system was derived. Parameters such as the volume fraction of the scatterer in the random scattering medium, the diameter of the scatterer, the distance between the object to be imaged and the surface of the random scattering medium were optimized to improve the image contrast and resolution. Moreover, for complicated objects, high contrast and quality images were achieved through the high-order intensity correlation measurement on the image plane, which may propel this imaging technique to practical applications.

  10. Acoustic Coherent Backscatter Enhancement from Aggregations of Point Scatterers

    Science.gov (United States)

    2014-09-30

    one computational element assigned to each scatterer. The computational burden of this approach is set by the inversion of the fully-populated N-by-N...B(φ) is the beamformed output of the receiving array, and [B]excluding peak is the array’s average beamformed output in directions near backscatter...but excluding the ACBE peak. The independent parameters of these investigations are A, k0, σs, s, R, L, φ or ϕ, X, Y, and Z, but the current problem

  11. Using Backscattering to Enhance Efficiency in Neutron Detectors

    DEFF Research Database (Denmark)

    Kittelmann, T.; Kanaki, K.; Klinkby, Esben Bryndt

    2017-01-01

    The principle of using strongly scattering materials to recover efficiency in detectors for neutron instruments, via backscattering of unconverted thermal neutrons, is discussed in general. The feasibility of the method is illustrated through Geant4-based simulations involving thermal neutrons...... impinging on a specific setup with a layer of polyethylene placed behind a single-layered boron-10 thin-film gaseous detector. The results show that detection efficiencies can be as much as doubled in the most ideal scenario, but with associated adverse contributions to spatial and timing resolutions of...

  12. Oscillations in the spectrum of nonlinear Thomson-backscattered radiation

    Directory of Open Access Journals (Sweden)

    C. A. Brau

    2004-02-01

    Full Text Available When an electron beam collides with a high-intensity laser beam, the spectrum of the nonlinear Thomson scattering in the backward direction shows strong oscillations like those in the spectrum of an optical klystron. Laser gain on the backward Thomson scattering is estimated using the Madey theorem, and the results suggest that Thomson-backscatter free-electron lasers are possible at wavelengths extending to the far uv using a terawatt laser beam from a chirped-pulse amplifier and a high-brightness electron beam from a needle cathode.

  13. Bulk media assay using backscattered Pu-Be neutrons

    CERN Document Server

    Csikai, J

    1999-01-01

    Spectral yields of elastically backscattered Pu-Be neutrons measured for graphite, water, polyethylene, liquid nitrogen, paraffin oil, SiO sub 2 , Al, Fe, and Pb slabs show a definite correlation with the energy dependence of the elastic scattering cross sections, sigma sub E sub L (E sub n). The C, N and O can be identified by the different structures in their sigma sub E sub L (E sub n) functions. The integrated spectral yields versus thickness exhibit saturation for each sample. The interrogated volume is limited by the presence of hydrogen in the sample. (author)

  14. A backscatter-suppressed beta spectrometer for neutron decay studies

    Energy Technology Data Exchange (ETDEWEB)

    Wietfeldt, F.E. [Department of Physics, Tulane University, New Orleans, LA 70118 (United States)]. E-mail: few@tulane.edu; Trull, C. [Department of Physics, Tulane University, New Orleans, LA 70118 (United States); Anderman, R. [Physics Department, Hamilton College, Clinton, NY 13323 (United States); Bateman, F.B. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Dewey, M.S. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Komives, A. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Thompson, A.K. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Balashov, S. [Kurchatov Institute, Moscow (Russian Federation); Mostovoy, Yu. [Kurchatov Institute, Moscow (Russian Federation)

    2005-02-11

    We describe a beta electron spectrometer for use in an upcoming experiment that will measure the beta-antineutrino correlation coefficient (a coefficient) in neutron beta decay. Electron energy is measured by a thick plastic scintillator detector. A conical array of plastic scintillator veto detectors is used to suppress events where the electron is backscattered. A Monte Carlo simulation of this device in the configuration of the a coefficient experiment is presented. The design, construction, and testing of a full-scale prototype device is described. We discuss the performance of this spectrometer with respect to its suitability for the experiment.

  15. Electrochemical Sensors for Clinic Analysis

    Directory of Open Access Journals (Sweden)

    Guang Li

    2008-03-01

    Full Text Available Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future.

  16. Measurement of backscattered 100 keV electrons on a solid substrate

    Science.gov (United States)

    Czaplewski, David A.; Ocola, Leonidas E.

    2011-11-01

    We have measured the intensity of backscattered 100 keV electrons on a silicon substrate as a function of distance up to 50 μm from the source. The intensity of backscattered electrons was determined by measuring the thickness changes in pre-exposed, isolated 100 nm crosses in a negative resist using atomic force microscopy. The electron backscattered range was measured to be 31.08 ± 0.30 μm and showed deviation from Gaussian behavior for radii larger than 30 μm. This method produces an accurate measurement of the backscattered range because it is process independent and covers a large data range.

  17. ILC beam energy measurement by means of laser Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Muchnoi, N. [Budker Inst. for Nuclear Physics, Novosibirsk (Russian Federation); Schreiber, H.J.; Viti, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2008-10-15

    A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered {gamma}-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of 10{sup -4} or better on a bunch-to-bunch basis while the electron and positron beams are in collision. (orig.)

  18. Control of collective FSBS and backscatter SRS through plasma composition

    Science.gov (United States)

    Rose, Harvey; Lushnikov, Pavel

    2005-10-01

    Nominal NIF parameters are near the collective forward SBS (FSBS) threshold (P. M. Lushnikov and H. A. Rose, Phys. Rev. Lett. 92, 255003 (2004), ``L&R''). It will be shown that being on this instability edge can be used as a control lever: a small amount of high Z dopant may lead to qualitative change in FSBS regime at fixed laser intensity, possibly reducing backscatter instability losses (Such results have already been observed, but absent SSD, a key aspect of our theory: R. M. Stevenson et al., Phys. Plasmas 11, 2709 (2004); L. J. Suter et al., 2738, ib.). Ponderomotive FSBS regimes are determined by the parameter I=F^2( vosc / vosc ve . - ve )^2( ne / ne nc . - nc ) / ( ne / ne nc . - nc ) ν . - ν, with ν the dimensionless ion acoustic damping coefficient and F the optic f/#. Analytical results will be presented which show a decrease of I1pt's threshold value through the addition of high Z dopant to low Z plasma, owing to increased thermal contribution to FSBS. Alternatively, one may raise the threshold by managing the value of νby, e.g., adding He to SiO2. For nominal NIF parameters, a range of He fraction in SiO2 plasma is predicted to suppress backscatter SRS while maintaining control of forward SBS.

  19. Backscattering measuring system for optimization of intravenous laser irradiation dose

    Science.gov (United States)

    Rusina, Tatyana V.; Popov, V. D.; Melnik, Ivan S.; Dets, Sergiy M.

    1996-11-01

    Intravenous laser blood irradiation as an effective method of biostimulation and physiotherapy becomes a more popular procedure. Optimal irradiation conditions for each patient are needed to be established individually. A fiber optics feedback system combined with conventional intravenous laser irradiation system was developed to control of irradiation process. The system consists of He-Ne laser, fiber optics probe and signal analyzer. Intravenous blood irradiation was performed in 7 healthy volunteers and 19 patients with different diseases. Measurements in vivo were related to in vitro blood irradiation which was performed in the same conditions with force-circulated venous blood. Comparison of temporal variations of backscattered light during all irradiation procedures has shown a strong discrepancy on optical properties of blood in patients with various health disorders since second procedure. The best cure effect was achieved when intensity of backscattered light was constant during at least five minutes. As a result, the optical irradiation does was considered to be equal 20 minutes' exposure of 3 mW He-Ne laser light at the end of fourth procedure.

  20. Pascal's triangle and the simulation of backscattering spectra

    Science.gov (United States)

    Bozoian, Michael

    1994-04-01

    Applying a well-known yield equation to a stack of very thin sublayers allows accurate simulations of homogeneous, thick-target, backscattering spectra. Explicit expressions, accurate to at least third degree in the areal density for the ion energy immediately before scattering and for the detected ion energy, are found. These expressions are in terms of binomial expansions of a quantity equaling the product of the areal density multiplied by a function of stopping cross section derivatives and areal density. One iterative parameter, taken as the near-surface yield, is required to properly normalize the simulation with respect to the experimental spectrum. Several thick target spectra, produced by bombarding helium ions with energies ranging over several MeV, are simulated using both Ziegler's 1977 [J.F. Ziegler, Helium Stopping Powers and Ranges in All Elements (Pergamon, New York, 1977)] and 1985 [J.F. Ziegler, J.P. Biersack and U. Littmark, The Stopping and Range of Ions in Solids (Pergamon, New York, 1985)] stopping compilations to ascertain the impact of these differing stopping cross sections on predictions of backscattering spectra.

  1. Classification of kidney and liver tissue using ultrasound backscatter data

    Science.gov (United States)

    Aalamifar, Fereshteh; Rivaz, Hassan; Cerrolaza, Juan J.; Jago, James; Safdar, Nabile; Boctor, Emad M.; Linguraru, Marius G.

    2015-03-01

    Ultrasound (US) tissue characterization provides valuable information for the initialization of automatic segmentation algorithms, and can further provide complementary information for diagnosis of pathologies. US tissue characterization is challenging due to the presence of various types of image artifacts and dependence on the sonographer's skills. One way of overcoming this challenge is by characterizing images based on the distribution of the backscatter data derived from the interaction between US waves and tissue. The goal of this work is to classify liver versus kidney tissue in 3D volumetric US data using the distribution of backscatter US data recovered from end-user displayed Bmode image available in clinical systems. To this end, we first propose the computation of a large set of features based on the homodyned-K distribution of the speckle as well as the correlation coefficients between small patches in 3D images. We then utilize the random forests framework to select the most important features for classification. Experiments on in-vivo 3D US data from nine pediatric patients with hydronephrosis showed an average accuracy of 94% for the classification of liver and kidney tissues showing a good potential of this work to assist in the classification and segmentation of abdominal soft tissue.

  2. Measuring and modeling the backscattering cross section of a leaf

    Science.gov (United States)

    Senior, T. B. A.; Sarabandi, K.; Ulaby, F. T.

    1987-01-01

    Leaves are a significant feature of any vegetation canopy, and for remote sensing purposes it is important to develop an effective model for predicting the scattering from a leaf. From measurements of the X band backscattering cross section of a coleus leaf in varying stages of dryness, it is shown that a uniform resistive sheet constitutes such a model for a planar leaf. The scattering is determined by the (complex) resistivity which is, in turn, entirely specified by the gravimetric moisture content of the leaf. Using an available asymptotic expression for the scattering from a rectangular resistive plate which includes, as a special case, a metallic plate whose resistivity is zero, the computed backscattering cross sections for both principal polarizations are found to be in excellent agreement with data measured for rectangular sections of leaves with different moisture contents. If the resistivity is sufficiently large, the asymptotic expressions do not differ significantly from the physical optics ones, and for naturally shaped leaves as well as rectangular sections, the physical optics approximation in conjunction with the resistive sheet model faithfully reproduces the dominant feataures of the scattering patterns under all moisture conditions.

  3. Observations of HF backscatter decay rates from HAARP generated FAI

    Science.gov (United States)

    Bristow, W. A.; Hysell, D. L.

    2016-12-01

    Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

  4. Variation of backscatter as an indicator of boundary layer structure

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, M. [UMIST, Dept. of Chemical Engineering, Manchester (United Kingdom); Hunter, G.C. [National Power, Swindon (United Kingdom)

    1997-10-01

    In this work we have developed software to display cross-sections of the variance of backscatter over a given sampling period in addition to its absolute mean. We have analyzed a series of Lidar cross-sections of elevated plumes dispersing into a convective BL and have then derived profiles both of the mean backscatter, , as a function of height and of its relative, shot-to-shot, variation, {radical} /. The latter is a measure of the homogeneity of the aerosol. There is no cheap device for measuring BL depths so we were interested in comparing depths estimated using our Lidar with those predicted by the current ADMS atmospheric dispersion model. This is based on integrating an energy budget to predict the BL development and as such relies on values for the initial lapse rate and for the surface sensible heat flux. A major shortcoming of the model appears to be that, in the absence of measurements, it must assume a default value for the former; the latter may be estimated from surface measurements but is very sensitive to the assumed availability of surface moisture. (LN)

  5. Automated determination of crystal orientations from electron backscattering patterns

    DEFF Research Database (Denmark)

    Lassen, Niels Christian Krieger

    1994-01-01

    The electron backscattering pattern (EBSP) technique is widely accepted as being an extremely powerful tool for measuring the crystallographic orientation of individual crystallites in polycrystalline materials. Procedures which allow crystal orientations to be calculated on the bases of the posi......The electron backscattering pattern (EBSP) technique is widely accepted as being an extremely powerful tool for measuring the crystallographic orientation of individual crystallites in polycrystalline materials. Procedures which allow crystal orientations to be calculated on the bases...... be collected by this method. This thesis describes the development and implementation of a system which enables crystallographic orientations to be obtained fully automatically through the use of computerized analysis and interpretation of EBSPs. More specifically, this thesis will describe the design...... determination of crystallographic orientations from EBSPs is accurate knowledge of three calibration parameters which describe the position of the point from which the patterns are emitted relative to the phosphor screen on which they are recorded. This thesis will describe a novel method by which...

  6. Three-beam aerosol backscatter correlation lidar for wind profiling

    Science.gov (United States)

    Prasad, Narasimha S.; Radhakrishnan Mylapore, Anand

    2017-03-01

    The development of a three-beam aerosol backscatter correlation (ABC) light detection and ranging (lidar) to measure wind characteristics for wake vortex and plume tracking applications is discussed. This is a direct detection elastic lidar that uses three laser transceivers, operating at 1030-nm wavelength with ˜10-kHz pulse repetition frequency and nanosec class pulse widths, to directly obtain three components of wind velocities. By tracking the motion of aerosol structures along and between three near-parallel laser beams, three-component wind speed profiles along the field-of-view of laser beams are obtained. With three 8-in. transceiver modules, placed in a near-parallel configuration on a two-axis pan-tilt scanner, the lidar measures wind speeds up to 2 km away. Optical flow algorithms have been adapted to obtain the movement of aerosol structures between the beams. Aerosol density fluctuations are cross-correlated between successive scans to obtain the displacements of the aerosol features along the three axes. Using the range resolved elastic backscatter data from each laser beam, which is scanned over the volume of interest, a three-dimensional map of aerosol density can be generated in a short time span. The performance of the ABC wind lidar prototype, validated using sonic anemometer measurements, is discussed.

  7. Investigation of sheared liquids by neutron backscattering and reflectivity

    CERN Document Server

    Wolff, M; Hock, R; Frick, B; Zabel, H

    2002-01-01

    We have investigated by neutron scattering structural and dynamical properties of water solutions of the triblock copolymer P85 under shear. To this end a shear cell that suits the requirements for neutron backscattering and another for reflectivity experiments have been built. In reflectivity measurements we find the polymer concentration (nominal concentration of 33% by weight) to vary right at the surface between 12% and 52% for hydrophilic or hydrophobic coated silicon wavers, for temperatures between 18 C and 73 C and for shear rates up to 2500 s sup - sup 1. Additional structural changes deeper in the bulk are also observed. On the backscattering instrument (IN10 at ILL) we find that the liquid appears to stick to the plates of the shear cell, implying an unusual macroscopic velocity distribution that differs from that found earlier for lubrication oils. We report further on changes of the quasielastic line width in the direction of the shear gradient for different temperatures and shear rates. (orig.)

  8. Extinction and backscatter cross sections of biological materials

    Science.gov (United States)

    Thomas, M. E.; Hahn, D. V.; Carr, A. K.; Limsui, D.; Carter, C. C.; Boggs, N. T.; Jackman, J.

    2008-04-01

    Aerosol backscatter and extinction cross-sections are required to model and evaluate the performance of both active and passive detection systems. A method has been developed that begins with laboratory measurements of thin films and suspensions of biological material to obtain the complex index refraction of the biological material from the UV to the LWIR. Using that result with particle size distribution and shape information as inputs to T-matrix or discrete dipole approximation (DDA) calculations yields the extinction cross-section and backscatter cross section as a function of wavelength. These are important inputs to the lidar equation. In a continuing effort to provide validated optical cross-sections, measurements have been made on a number of high purity biological species in the laboratory as well as measurements of material released at recent field tests. The resulting observed differences between laboratory and field measurements aid in distinguishing between intrinsic and extrinsic effects, which can affect the characteristic signatures of important biological aerosols. A variety of biological and test aerosols are examined, including Bacillus atrophaeus (BG), and Erwina, ovalbumin, silica and polystyrene.

  9. Observations of 2D Doppler backscattering on MAST

    CERN Document Server

    Thomas, D A; Freethy, S J; Huang, B K; Shevchenko, V F; Vann, R G L

    2015-01-01

    The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D Doppler backscattering (DBS) experiments on MAST. SAMI actively probes the plasma edge using a wide (+-40 degrees vertical and horizontal) and tuneable (10-35.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24 degrees FWHM at 10-34.5 GHz. This capability is unique to SAMI and is an entirely novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial measurements of phenomena observed on conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch an...

  10. Electrochemical Science and Technology

    CERN Document Server

    Oldham, Keith; Bond, Alan

    2011-01-01

    The book addresses the scientific principles underlying electrochemistry. Starting with the basic concepts of electricity, the early chapters discuss the physics and chemistry of the materials from which electrochemical cells are constructed and the properties that make these materials appropriate as cell components. Much of the importance of electrochemistry lies in the conversion of electrical energy into chemical energy and vice versa; the thermodynamics of these processes is described, in the context of a wide range of applications of these interconversions. An electrode is a surface at wh

  11. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

    Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

    2012-01-01

    The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment....... The curve visually shows students that the best HER catalysts are characterized by an optimal hydrogen binding energy (reactivity), as stated by the Sabatier principle. In addition, students may use this volcano curve to predict the activity of an untested catalyst solely from the catalyst reactivity...

  12. Electrochemical photovoltaic cells and electrodes

    Science.gov (United States)

    Skotheim, Terje A.

    1984-01-01

    Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

  13. Thermodynamics of irreversible electrochemical phenomena

    NARCIS (Netherlands)

    Groot, S.R. de; Mazur, P.; Tolhoek, H.A.

    1953-01-01

    A discussion from first principles is given of the energy and entropy laws in electrochemical systems. It is found that it is possible to clarify such controversial concepts as the form of the second law and the role of the electrochemical potential in the systems concerned.

  14. Electrochemical biosensors for hormone analyses.

    Science.gov (United States)

    Bahadır, Elif Burcu; Sezgintürk, Mustafa Kemal

    2015-06-15

    Electrochemical biosensors have a unique place in determination of hormones due to simplicity, sensitivity, portability and ease of operation. Unlike chromatographic techniques, electrochemical techniques used do not require pre-treatment. Electrochemical biosensors are based on amperometric, potentiometric, impedimetric, and conductometric principle. Amperometric technique is a commonly used one. Although electrochemical biosensors offer a great selectivity and sensitivity for early clinical analysis, the poor reproducible results, difficult regeneration steps remain primary challenges to the commercialization of these biosensors. This review summarizes electrochemical (amperometric, potentiometric, impedimetric and conductometric) biosensors for hormone detection for the first time in the literature. After a brief description of the hormones, the immobilization steps and analytical performance of these biosensors are summarized. Linear ranges, LODs, reproducibilities, regenerations of developed biosensors are compared. Future outlooks in this area are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Plasmonic Imaging of Electrochemical Impedance.

    Science.gov (United States)

    Yuan, Liang; Tao, Nongjian; Wang, Wei

    2017-06-12

    Electrochemical impedance spectroscopy (EIS) measures the frequency spectrum of an electrochemical interface to resist an alternating current. This method allows label-free and noninvasive studies on interfacial adsorption and molecular interactions and has applications in biosensing and drug screening. Although powerful, traditional EIS lacks spatial resolution or imaging capability, hindering the study of heterogeneous electrochemical processes on electrodes. We have recently developed a plasmonics-based electrochemical impedance technique to image local electrochemical impedance with a submicron spatial resolution and a submillisecond temporal resolution. In this review, we provide a systematic description of the theory, instrumentation, and data analysis of this technique. To illustrate its present and future applications, we further describe several selected samples analyzed with this method, including protein microarrays, two-dimensional materials, and single cells. We conclude by summarizing the technique's unique features and discussing the remaining challenges and new directions of its application.

  16. High-Speed Electrochemical Imaging.

    Science.gov (United States)

    Momotenko, Dmitry; Byers, Joshua C; McKelvey, Kim; Kang, Minkyung; Unwin, Patrick R

    2015-09-22

    The design, development, and application of high-speed scanning electrochemical probe microscopy is reported. The approach allows the acquisition of a series of high-resolution images (typically 1000 pixels μm(-2)) at rates approaching 4 seconds per frame, while collecting up to 8000 image pixels per second, about 1000 times faster than typical imaging speeds used up to now. The focus is on scanning electrochemical cell microscopy (SECCM), but the principles and practicalities are applicable to many electrochemical imaging methods. The versatility of the high-speed scan concept is demonstrated at a variety of substrates, including imaging the electroactivity of a patterned self-assembled monolayer on gold, visualization of chemical reactions occurring at single wall carbon nanotubes, and probing nanoscale electrocatalysts for water splitting. These studies provide movies of spatial variations of electrochemical fluxes as a function of potential and a platform for the further development of high speed scanning with other electrochemical imaging techniques.

  17. AC loss properties of Bi-2212 rutherford-type cables; Bi-2212 razafuodo gata asshuku seikei dotai no koryu sonshitsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Y.; Matsumura, K.; Kajikawa, K.; Iwakuma, M.; Funaki, K. [Kyushu Univ., Fukuoka (Japan); Hasegawa, T. [Showa Electric Wire and Cable Co., Ltd., Kanagawa (Japan); Kasahara, H.; Akita, S. [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

    2000-05-29

    With the aim of the application to SMES, it advances the development of the large-capacity oxide superconducting wire rod. A current capacity per 1 is small for present oxide superconducting wire rod. And, it needs the development of method of improving of mechanical strength of wire rod in the large magnet like SMES, because it receives the mighty electromagnetic force. It produced Rutherford type conductor, which made the Ni unit alloy to be the reinforcement using Bi-2212 cross section wire rod as a trial for solving these problems experimentally. In this study, it measured ac loss on produced conductor and the wire, which constitutes this, and it evaluated the electromagnetic property. (NEDO)

  18. Crystallographic preferred orientation (CPO) of gypsum measured by electron backscatter diffraction (EBSD).

    Science.gov (United States)

    Hildyard, R C; Prior, D J; Mariani, E; Faulkner, D R

    2009-12-01

    An investigation by electron backscatter diffraction on gypsum shows that this technique can be used to study the microstructures and crystallographic preferred orientation of gypsum. Presented here are the methods, verification tests and data obtained from a naturally deformed sample of gypsum-rich rock. The electron backscatter diffraction data show the sample has a strong crystallographic preferred orientation.

  19. A multivariate correlation analysis of high-frequency bottom backscattering strength measurements with geotechnical parameters

    NARCIS (Netherlands)

    Simons, D.G.; Snellen, M.; Ainslie, M.A.

    2007-01-01

    Sound backscattered from the seabed has been measured in a 10 × 10-nmi2 region of the North Sea, characterized by a variety of bottom types, including mud, sand, and gravel. The backscattering strength measurements are made by a forward-looking sonar, operating at 100 kHz and tilted at an angle of

  20. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  1. Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography.

    Science.gov (United States)

    Rice, Katherine P; Chen, Yimeng; Prosa, Ty J; Larson, David J

    2016-06-01

    There are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.

  2. Time-of-flight detector for heavy ion backscattering spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, J.A.; Banks, J.C.; Doyle, B.L. [Sandia National Labs., Albuquerque, NM (United States). Ion Solid Interactions and Defect Physics Dept.

    1994-04-01

    This report describes the results of a two-year laboratory directed research and development project to explore advanced concepts in Heavy Ion Backscattering Spectrometry (HIBS), undertaken with the goal of extending the sensitivity of this relatively new technique to levels unattainable by any other existing trace element surface analysis. Improvements in sensitivity are required for the application of HIBS to contamination control in the microelectronics industry. Tools with sensitivity approaching 10{sup 8} atoms/cm{sup 2} are expected to be essential for enabling advanced IC production by the year 2000. During the project the authors developed a new analysis chamber with channeling goniometer and a prototype time-of-flight detector with a demonstrated sensitivity of {approximately} 5 {times} 10{sup 8} atoms/cm{sup 2} for Au on Si and {approximately} 5 {times} 10{sup 10} for Fe, and sufficient mass resolution to separate contributions from Fe and Cu.

  3. Back-scatter based whispering gallery mode sensing.

    Science.gov (United States)

    Knittel, Joachim; Swaim, Jon D; McAuslan, David L; Brawley, George A; Bowen, Warwick P

    2013-10-17

    Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive real-time observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors.

  4. Remote identification of a shipwreck site from MBES backscatter.

    Science.gov (United States)

    Masetti, Giuseppe; Calder, Brian

    2012-11-30

    The method described attempts to remotely identify the shape of an anthropogenic object, such as a wreck of a modern vessel, using reflectivity data from Multi-Beam Echosounder (MBES) systems. In the beam domain, the backscatter strength values - geometrically and radiometrically corrected - are used to extract a large number of Gray Level Co-occurrence Matrix (GLCM) features with different input parameters. Principal Component Analysis (PCA) is applied in order to achieve dimensionality reduction whilst a K-means algorithm clusters as "shipwreck site" a large number of beams for each line. After the geo-referencing process, a K-nearest-neighbors (K-NN) technique is applied as a filter for possible misclassifications. Finally, the shape of the shipwreck site is defined from the georeferenced beams using the α-shape method, constructing an output compatible with Geographic Information Systems (GIS). Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Distribution of atmospheric aerosols and CO2 lidar backscatter simulation

    Science.gov (United States)

    Kent, G. S.; Wang, P. H.; Deepak, A.; Farrukh, U. O.

    1985-01-01

    Development of a Global Wind Measurement Satellite System (WINDSAT) (NOAA, 1981) requires a knowledge of the global characteristics of the free tropospheric and lower stratospheric aerosol. In particular, there is a need to document the behavior of the aerosol backscattering function, at CO2 laser wavelengths, beta sub CO2, as a function of space and time. There is, however, a relative lack of data for the free troposphere, particularly over the remoter regions of the globe, as compared with that for the boundary layer and the stratosphere. Moreover, because of variations in concentration that occur as a function of space and time, large data sets are required to obtain meaningful averages. A recent study by Kent et al. (1985) uses three distinct tropospheric aerosol data sets in order to obtain an improved global model of the general aerosol characteristics, including variation of beta sub CO2 with latitude, season, and altitude. The more important findings are summarized.

  6. Ray-based calculations of laser backscatter in ICF targets

    CERN Document Server

    Strozzi, D J; Hinkel, D E; Froula, D H; London, R A; Callahan, D A

    2008-01-01

    A steady-state model for Brillouin and Raman backscatter along a laser ray path is presented. The daughter plasma waves are treated in the strong damping limit, and have amplitudes given by the (linear) kinetic response to the ponderomotive drive. Pump depletion, inverse-bremsstrahlung damping, bremsstrahlung emission, Thomson scattering off density fluctuations, and whole-beam focusing are included. The numerical code Deplete, which implements this model, is described. The model is compared with traditional linear gain calculations, as well as ``plane-wave'' simulations with the paraxial propagation code pF3D. Comparisons with Brillouin-scattering experiments at the Omega Laser Facility show that laser speckles greatly enhance the reflectivity over the Deplete results. An approximate upper bound on this enhancement is given by doubling the Deplete coupling coefficient. Analysis with Deplete of an ignition design for the National Ignition Facility (NIF), with a peak radiation temperature of 285 eV, shows enco...

  7. Source point calibration from an arbitrary electron backscattering pattern

    DEFF Research Database (Denmark)

    Lassen, Niels Christian Krieger

    1999-01-01

    Precise knowledge of the position of the source point is a requirement if electron backscattering patterns (EBSPs) are to be used for crystal orientation measurements or other types of measurements which demand a geometrical analysis of the patterns. Today, possibly the most popular method...... for locating the source point is a computational technique which uses the positions of a number of indexed Kikuchi bands for calculating the coordinates of the point. A serious limitation of this calibration technique is, however, that the localized bands must first be indexed, which is difficult...... by this new calibration procedure is the same crystallographic information which is used for normal indexing of EBSPs. The procedure is shown to work successfully with patterns from a simple cubic crystal, as well as with patterns from an orthorhombic BiSCCO superconductor. In the former case, four bands...

  8. Backscatter absorption gas imaging systems and light sources therefore

    Energy Technology Data Exchange (ETDEWEB)

    Kulp, Thomas Jan [Livermore, CA; Kliner, Dahv A. V. [San Ramon, CA; Sommers, Ricky [Oakley, CA; Goers, Uta-Barbara [Campbell, NY; Armstrong, Karla M [Livermore, CA

    2006-12-19

    The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

  9. Modeling low-coherence enhanced backscattering using Monte Carlo simulation.

    Science.gov (United States)

    Subramanian, Hariharan; Pradhan, Prabhakar; Kim, Young L; Liu, Yang; Li, Xu; Backman, Vadim

    2006-08-20

    Constructive interference between coherent waves traveling time-reversed paths in a random medium gives rise to the enhancement of light scattering observed in directions close to backscattering. This phenomenon is known as enhanced backscattering (EBS). According to diffusion theory, the angular width of an EBS cone is proportional to the ratio of the wavelength of light lambda to the transport mean-free-path length l(s)* of a random medium. In biological media a large l(s)* approximately 0.5-2 mm > lambda results in an extremely small (approximately 0.001 degrees ) angular width of the EBS cone, making the experimental observation of such narrow peaks difficult. Recently, the feasibility of observing EBS under low spatial coherence illumination (spatial coherence length Lsc path lengths and thus resulting in an increase of more than 100 times in the angular width of low coherence EBS (LEBS) cones. However, a conventional diffusion approximation-based model of EBS has not been able to explain such a dramatic increase in LEBS width. We present a photon random walk model of LEBS by using Monte Carlo simulation to elucidate the mechanism accounting for the unprecedented broadening of the LEBS peaks. Typically, the exit angles of the scattered photons are not considered in modeling EBS in the diffusion regime. We show that small exit angles are highly sensitive to low-order scattering, which is crucial for accurate modeling of LEBS. Our results show that the predictions of the model are in excellent agreement with the experimental data.

  10. THE LOW BACKSCATTERING TARGETS CLASSIFICATION IN URBAN AREAS

    Directory of Open Access Journals (Sweden)

    L. Shi

    2012-07-01

    Full Text Available The Polarimetric and Interferometric Synthetic Aperture Radar (POLINSAR is widely used in urban area nowadays. Because of the physical and geometric sensitivity, the POLINSAR is suitable for the city classification, power-lines detection, building extraction, etc. As the new X-band POLINSAR radar, the china prototype airborne system, XSAR works with high spatial resolution in azimuth (0.1 m and slant range (0.4 m. In land applications, SAR image classification is a useful tool to distinguish the interesting area and obtain the target information. The bare soil, the cement road, the water and the building shadow are common scenes in the urban area. As it always exists low backscattering sign objects (LBO with the similar scattering mechanism (all odd bounce except for shadow in the XSAR images, classes are usually confused in Wishart-H-Alpha and Freeman-Durden methods. It is very hard to distinguish those targets only using the general information. To overcome the shortage, this paper explores an improved algorithm for LBO refined classification based on the Pre-Classification in urban areas. Firstly, the Pre-Classification is applied in the polarimetric datum and the mixture class is marked which contains LBO. Then, the polarimetric covariance matrix C3 is re-estimated on the Pre-Classification results to get more reliable results. Finally, the occurrence space which combining the entropy and the phase-diff standard deviation between HH and VV channel is used to refine the Pre-Classification results. The XSAR airborne experiments show the improved method is potential to distinguish the mixture classes in the low backscattering objects.

  11. Statistics of vertical backscatter profiles of cirrus clouds

    Directory of Open Access Journals (Sweden)

    P. Veglio

    2011-12-01

    Full Text Available A nearly global statistical analysis of vertical backscatter and extinction profiles of cirrus clouds collected by the CALIOP lidar, on-board of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, is presented.

    Statistics on frequency of occurrence and distribution of bulk properties of cirrus clouds in general and, for the first time, of horizontally homogeneous (on a 5-km field of view cirrus clouds only are provided. Annual and seasonal backscatter profiles (BSP are computed for the horizontally homogeneous cirri. Differences found in the day/night cases and for midlatitudes and tropics are studied in terms of the mean physical parameters of the clouds from which they are derived.

    The relationship between cloud physical parameters (optical depth, geometrical thickness and temperature and the shape of the BSP is investigated. It is found that cloud geometrical thickness is the main parameter affecting the shape of the mean CALIOP BSP. Specifically, cirrus clouds with small geometrical thicknesses show a maximum in mean BSP curve located near cloud top. As the cloud geometrical thickness increases the BSP maximum shifts towards cloud base. Cloud optical depth and temperature have smaller effects on the shape of the CALIOP BSPs. In general a slight increase in the BSP maximum is observed as cloud temperature and optical depth increase.

    In order to fit mean BSPs, as functions of geometrical thickness and position within the cloud layer, polynomial functions are provided. The impact on satellite radiative transfer simulations in the infrared spectrum when using either a constant ice-content (IWC along the cloud vertical dimension or an IWC profile derived from the BSP fitting functions is evaluated. It is, in fact, demonstrated that, under realistic hypotheses, the mean BSP is linearly proportional to the IWC profile.

  12. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).

  13. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    1996-08-01

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  14. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  15. Seafloor classification of the mound and channel provinces of the Porcupine Seabight: An application of the multibeam angular backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Beyer, A.; Chakraborty, B.; Schenke, H.W.

    strength. Three major parameters are utilized to classify four different seafloor provinces of the Porcupine Seabight by employing a semi-empirical method to analyse multibeam angular backscatter data. The predicted backscatter response, which has been...

  16. Biomedical Perspective of Electrochemical Nanobiosensor

    National Research Council Canada - National Science Library

    Priti Singh Shailendra Kumar Pandey Jyoti Singh Sameer Srivastava Sadhana Sachan Sunil Kumar Singh

    2016-01-01

    Electrochemical biosensor holds great promise in the biomedical area due to its enhanced specificity, sensitivity, label-free nature and cost effectiveness for rapid point-of-care detection of diseases at bedside...

  17. Electrochemical biofilm control: A review

    Science.gov (United States)

    Sultana, Sujala T; Babauta, Jerome T; Beyenal, Haluk

    2015-01-01

    One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are to (1) present the current status of knowledge regarding electrochemical biofilm control, (2) establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it, (3) discuss current proposed mechanisms, and (4) introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing data sets across the literature and generating comparable data sets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use. PMID:26592420

  18. Printed Electrochemical Instruments for Biosensors

    OpenAIRE

    Beni, Valerio; Nilsson, D.; Arven, P.; Norberg, P.; Gustafsson, G.; Turner, Anthony

    2015-01-01

    Mobile diagnostics for healthcare, food safety and environmental monitoring, demand a new generation of inexpensive sensing systems suitable for production in high volume. Herein we report on the development of a new disposable electrochemical instrument exploiting the latest advances in printed electronics and printed biosensors. The current system is manufactured under ambient conditions with all interconnections printed; electrochemical measurements and data elaboration are realized by the...

  19. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    1997-01-01

    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  20. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  1. Relationship of Light Scattering at an Angle in the Backward Direction to the Backscattering Coefficient

    Science.gov (United States)

    Boss, Emmanuel; Pegau, W. Scott

    2001-10-01

    We revisit the problem of computing the backscattering coefficient based on the measurement of scattering at one angle in the back direction. Our approach uses theory and new observations of the volume scattering function (VSF) to evaluate the choice of angle used to estimate bb . We add to previous studies by explicitly treating the molecular backscattering of water (bbw ) and its contribution to the VSF shape and to bb . We find that there are two reasons for the tight correlation between observed scattering near 120 and the backscattering coefficient reported by Oishi [Appl. Opt. 29, 4658, (1990) , namely, that (1) the shape] of the VSF of particles (normalized to the backscattering) does not vary much near that angle for particle assemblages of differing optical properties and size, and (2) the ratio of the VSF to the backscattering is not sensitive to the contribution by water near this angle. We provide a method to correct for the water contribution to backscattering when single-angle measurements are used in the back direction (for angles spanning from near 90 to 160 ) that should provide improved estimates of the backscattering coefficient.

  2. 100 keV electron backscattered range and coefficient for silicon.

    Energy Technology Data Exchange (ETDEWEB)

    Czaplewski, D.A.; Ocola, L.E. (Center for Nanoscale Materials)

    2012-01-01

    The authors have measured the range and intensity of backscattered electrons in silicon from a 100 keV source using a process independent method. Backscattered electrons contributed to the total dose of features written in a negative tone electron beam resist. Instead of measuring the height of the resist and using a contrast curve to convert the resist height to dose, the heights of the features were made equal by adjusting the backscattered contribution through dose assignments. Creating features of equal height eliminated the need to use a contrast curve to convert from resist height to total dose. Also, it allowed for measurements of the backscattered contribution from larger distances. Using a circularly symmetric torus pattern, the three-dimensional backscatter problem was reduced to a 1-dimensional Gaussian form. The authors measured the range of the backscattered electrons, {beta}, to be 31.08 {+-} 0.06 {micro}m. By varying the writing dose of the pattern, we determined the backscatter coefficient, {eta}, to be 0.63 {+-} 0.03.

  3. Gas-Filled Targets to Study Laser Backscatter on the National Ignition Facility

    Science.gov (United States)

    London, R. A.; Williams, E. A.; Hinkel, D. E.; Moody, J. D.; Suter, L. J.

    2009-11-01

    To achieve indirect drive fusion at the National Ignition Facility (NIF), laser beams must propagate through several millimeters of high-density plasma to reach the hohlraum walls. Stimulated Brillouin and Raman backscatter could create problems with energetics and/or symmetry. Laser backscatter at NIF will be diagnosed with full aperture backscatter systems (FABS) and near backscatter imagers (NBI). Several gas-filled targets (``gas pipes'') have been designed to provide backscatter sources to commission the diagnostics. The 7-mm long gas pipes are filled with various gases, including C5H12 and CO2, and are irradiated by a NIF quad with 16 kJ of energy in 2-4 ns pulses. We describe the design of the gas pipes using hydrodynamics and laser-plasma-interaction computer codes. The relationship between the design parameters (gas composition and density and laser pulse shape) and the character of the backscatter (Brillouin versus Raman and narrow versus broad angle) are discussed. Comparisons of predicted and measured backscatter distributions and levels are discussed.

  4. Radar backscatter from plasma irregularities of the lower E region induced by neutral turbulence

    Directory of Open Access Journals (Sweden)

    K. Schlegel

    Full Text Available Recently, one of the authors (A. V. G. developed a theory of low-frequency plasma irregularities which are created as a consequence of neutral turbulence in the D and lower E regions. In the following this theory will be applied to coherent backscatter experiments with radars in a frequency range between 5 and 150 MHz. We discuss the dependence of the backscatter cross-section on ionospheric as well as on turbulence parameters. The backscatter increases strongly with decreasing radar frequency. Above 15 MHz the effects discussed here can probably only be detected by very powerful radars with large antenna arrays.

  5. Fiber sensor identification based on incoherent Rayleigh backscatter measurements in the frequency domain

    Science.gov (United States)

    Koeppel, Max; Engelbrecht, Rainer; Werzinger, Stefan; Schmauss, Bernhard

    2017-04-01

    In this work, a fiber identification method based on incoherent optical frequency domain reflectometry (IOFDR) measurements is introduced. The proposed method uses the characteristic interference pattern of IOFDR Rayleigh backscatter measurements with a broadband light source to unambiguously recognize different initially scanned fiber segments. The recognition is achieved by cross-correlating the spatially resolved Rayleigh backscatter profile of the fiber segment under test with a initially measured and stored backscatter profile. This profile was found to be relatively insensitive to temperature changes. It is shown that identification is possible even if the fiber segment in question is installed subsequent to 300m of lead fiber.

  6. Principal component analysis applied to multiwavelength lidar aerosol backscatter and extinction measurements.

    Science.gov (United States)

    Donovan, D P; Carswell, A I

    1997-12-20

    The use of powerful Raman backscatter lidars enables one to measure the stratospheric aerosol extinction profile independently of the backscatter, thereby obtaining additional information to aid in retrieving the physical characteristics of the sampled aerosol. We used principal component analysis to construct a self-consistent method for the retrieval of aerosol bulk physical and optical properties from multiwavelength elastic and/or inelastic Raman backscatter lidar signals. The procedure is applied to synthetic and actual lidar signals. We found that aerosol surface area and volume can be usefully estimated and that the use of Raman-derived extinction data leads to a notable improvement in the accuracy of the estimations.

  7. Spectroscopic and electrochemical studies of electrochromic hydrated nickel oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Yu, P.C.; Nazri, G.; Lampert, C.M.

    1986-07-01

    The electrochromic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (T/sub p/) can be switched from T/sub p/(bleached) = 0.77 to T/sub p/(colored) = 0.21, and the solar transmittance (T/sub S/) can be switched from T/sub S/(bleached) = 0.73 to T/sub S/(colored = 0.35. Also reported is the near-infrared transmittance (T/sub NIR/), which was found to switch from T/sub NIR/(bleached) = 0.72 to T/sub NIR/(colored) = 0.55 for a film thickness of 500 A. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a composition of NiO/sub 1.0/ (dehydrated). Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(OH)/sub 2/ ..-->.. NiOOH + H/sup +/ + e/sup -/. Voltammetry also showed that the switching of the film is controlled by the diffusion of protons, where OH/sup -/ plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

  8. A Dictionary Approach to Electron Backscatter Diffraction Indexing.

    Science.gov (United States)

    Chen, Yu H; Park, Se Un; Wei, Dennis; Newstadt, Greg; Jackson, Michael A; Simmons, Jeff P; De Graef, Marc; Hero, Alfred O

    2015-06-01

    We propose a framework for indexing of grain and subgrain structures in electron backscatter diffraction patterns of polycrystalline materials. We discretize the domain of a dynamical forward model onto a dense grid of orientations, producing a dictionary of patterns. For each measured pattern, we identify the most similar patterns in the dictionary, and identify boundaries, detect anomalies, and index crystal orientations. The statistical distribution of these closest matches is used in an unsupervised binary decision tree (DT) classifier to identify grain boundaries and anomalous regions. The DT classifies a pattern as an anomaly if it has an abnormally low similarity to any pattern in the dictionary. It classifies a pixel as being near a grain boundary if the highly ranked patterns in the dictionary differ significantly over the pixel's neighborhood. Indexing is accomplished by computing the mean orientation of the closest matches to each pattern. The mean orientation is estimated using a maximum likelihood approach that models the orientation distribution as a mixture of Von Mises-Fisher distributions over the quaternionic three sphere. The proposed dictionary matching approach permits segmentation, anomaly detection, and indexing to be performed in a unified manner with the additional benefit of uncertainty quantification.

  9. Ray-Based Calculations of Backscatter in Laser Fusion Targets

    Energy Technology Data Exchange (ETDEWEB)

    Strozzi, D J; Williams, E A; Hinkel, D E; Froula, D H; London, R A; Callahan, D A

    2008-02-26

    A steady-state model for Brillouin and Raman backscatter along a laser ray path is presented. The daughter plasma waves are treated in the strong damping limit, and have amplitudes given by the (linear) kinetic response to the ponderomotive drive. Pump depletion, inverse-bremsstrahlung damping, bremsstrahlung emission, Thomson scattering off density fluctuations, and whole-beam focusing are included. The numerical code deplete, which implements this model, is described. The model is compared with traditional linear gain calculations, as well as 'plane-wave' simulations with the paraxial propagation code pf3d. Comparisons with Brillouin-scattering experiments at the OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, p. 495 (1997)] show that laser speckles greatly enhance the reflectivity over the deplete results. An approximate upper bound on this enhancement, motivated by phase conjugation, is given by doubling the deplete coupling coefficient. Analysis with deplete of an ignition design for the National Ignition Facility (NIF) [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, p. 755 (1994)], with a peak radiation temperature of 285 eV, shows encouragingly low reflectivity. Doubling the coupling to bound the speckle enhancement suggests a less optimistic picture. Re-absorption of Raman light is seen to be significant in this design.

  10. Diffuse ultrasonic backscatter using a multi-Gaussian beam model.

    Science.gov (United States)

    Li, Xiongbing; Song, Yongfeng; Arguelles, Andrea P; Turner, Joseph A

    2017-07-01

    Diffuse ultrasonic backscatter is widely used to evaluate microstructural parameters of heterogeneous materials. Recent singly scattered response (SSR) models utilize a single-Gaussian beam (SGB) assumption which is expected to have limitations. Following a similar formalism, a model is presented using a multi-Gaussian beam (MGB) assumption to characterize the transducer beam for longitudinal-to-longitudinal scattering at normal incidence through an interface with arbitrary curvature. First, the Wigner transform of the transducer field is defined using conjugate double-layer MGB expressions. The theoretical analysis shows that ten groups of Gaussian beams are sufficient for convergence. Compared with the SGB-SSR curve, the shape of MGB-SSR curve is positive skewed. Differences between the MGB-SSR model and the SGB-SSR model are quantified and shown to be complex functions of frequency, sample curvature, transducer parameters, and focal depth in the material. Finally, both models are used to fit experimental spatial variance data from a 304 stainless steel pipe with planar, convex, and concave surfaces. The results show that the MGB-SSR has some characteristics suggesting a better fit to the experiments. However, both models result in grain size estimates within the uncertainty of the optical microscopy suggesting that the SGB is sufficient for normal incidence pulse-echo measurements.

  11. Taylor Dispersion Analysis of Polysaccharides Using Backscattering Interferometry.

    Science.gov (United States)

    Saetear, Phoonthawee; Chamieh, Joseph; Kammer, Michael N; Manuel, Thomas J; Biron, Jean-Philippe; Bornhop, Darryl J; Cottet, Hervé

    2017-06-20

    Taylor dispersion analysis (TDA) allows the determination of the molecular diffusion coefficient (D) or the hydrodynamic radius (R h ) of a solute from the peak broadening of a plug of solute in a laminar Poiseuille flow. The main limitation plaguing the broader applicability of TDA is the lack of a sensitive detection modality. UV absorption is typically used with TDA but is only suitable for UV-absorbing or derivatized compounds. In this work, we present a development of the TDA method for non-UV absorbing compounds by using a universal detector based on refractive index (RI) sensing with backscattering interferometry (BSI). BSI was interfaced to a capillary electrophoresis-UV instrument using a polyimide coated fused silica capillary and an in-house designed flow-cell assembly. Polysaccharides were selected to demonstrate the application of TDA-BSI for size characterization. Under the conditions of validity of TDA, D and R h average values and the entire R h distributions were obtained from the (poly)saccharide taylorgrams, including non-UV absorbing polymers.

  12. Electrochemical Hydrogen Peroxide Generator

    Science.gov (United States)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials

  13. A comparison of satellite scintillation measurements with HF radar backscatter characteristics

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    2005-12-01

    Full Text Available We examine the correspondence between high latitude ionospheric scintillation measurements made at 250MHz with the occurrence of 10MHz HF coherent radar backscatter, on 13 and 14 December 2002. We demonstrate that when the ionospheric intersection point of the scintillation measurements is co-located with significant HF radar backscatter, the observed scintillation, quantified by the S4 index, is elevated. Conversely, when the radar indicates that backscatter is observed away from the intersection point due to movements of the auroral zone, the observed scintillation is low. This suggests that scintillation is highly location-dependent, being enhanced in the auroral zone and being lower at sub-auroral latitudes. The coexistence of scintillation and HF radar backscatter, produced by ionospheric density perturbations with scale sizes of 100s of metres and ~15 m, respectively, suggests that a broad spectrum of density fluctuations is found in the auroral zone.

  14. High-resolution multibeam backscatter data - northern Channel Islands region, southern California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data release presents data for 5-m resolution acoustic-backscatter data of the northern Channel Islands region, southern California. The raster data files are...

  15. Integrating multibeam backscatter angular response, mosaic and bathymetry data for benthic habitat mapping

    National Research Council Canada - National Science Library

    Che Hasan, Rozaimi; Ierodiaconou, Daniel; Laurenson, Laurie; Schimel, Alexandre

    2014-01-01

    ..., and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth...

  16. Seabottom characterization using multibeam echosounder angular backscatter: An application of the composite roughness theory

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Schenke, H.W.; Kodagali, V.N.; Hagen, R.

    Composite roughness theory is used to characterize Southern Ocean bottom backscatter (multibeam) data. Spectral parameters based on Helmholtz-Kirchhof's theory (1) are determined from measured near-normal incidence values. A splicing technique using...

  17. Multi-beam backscatter image data processing techniques employed to EM 1002 system

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, W.A.; Chakraborty, B.

    due to the presence of inherent artifacts. Generally, angular backscatter strength data show higher values towards the normal incidence angles especially for smooth seafloor compared to outer-beam angles. Therefore, off-line corrections are essential...

  18. Fine scale analyses of a coralline bank mapped using multi-beam backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Menezes, A.A.A.; Naik, M.; Fernandes, W.A.; Haris, K.; Chakraborty, B.; Estiberio, S.; Lohani, R.B.

    unsupervised self-organizing maps (SOM) architecture is used to determine the existence of six classes. Thereafter, 55 segments were identified for data segmentation, employing six profiles selected from the backscatter maps, using the fuzzy c-means (FCM...

  19. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Thomas, US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  20. Backscatter 0.5m TIFF Mosaic of St. Thomas, US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  1. Simrad em3002d Backscatter imagery of Penguin Bank, Molokai, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery extracted from gridded bathymetry of Penguin Bank, Molokai, Hawaii, USA. These data provide almost complete coverage between 0 and 100 meters....

  2. Pseudo sidescan images from backscatter amplitude data of the Hydrosweep multibean sonar system

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.; Hagen, R.; Schenke, H.W.

    Using the rms (root mean square) backscatter amplitude values, a procedure was evolved to generate pseudo sidescan images. A comparison of the pseudo sidescan image with actual Hydrosweep sidescan image, from an area covering a pear shaped seamount...

  3. Assessing the contamination of SuperDARN global convection maps by non-F-region backscatter

    Directory of Open Access Journals (Sweden)

    G. Chisham

    2002-01-01

    Full Text Available Global convection mapping using line-of-sight Doppler velocity data from the Super Dual Auroral Radar Network (SuperDARN is now an accepted method of imaging high-latitude ionospheric convection. This mapping process requires that the flow measured by the radars is defined solely by the convection electric field. This is generally only true of radar backscatter from the ionospheric F-region. We investigate the extent to which the E-region and ground backscatter in the SuperDARN data set may be misidentified as F-region backscatter, and assess the contamination of global convection maps which results from the addition of this non-F-region backscatter. We present examples which highlight the importance of identifying this contamination, especially with regard to the mesoscale structure in the convection maps.Key words. Ionosphere (plasma convection – Radio science (radio wave propagation; instruments and techniques

  4. CRED Reson 8101 multibeam backscatter data from the islands and banks in the Mariana archipelago, 2007.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the Mariana archipelago between the U.S. Territory of Guam and Uracas Island in the Commonwealth...

  5. A Compact In Situ Sensor for Measurement of Absorption and Backscattering in Natural Waters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop an active sensor for in situ measurement of the inherent optical properties (IOPs) absorption and backscattering at multiple wavelengths....

  6. Atmospheric aerosol load morphological classification and retrieved visibility based on lidar backscatter measurements

    CSIR Research Space (South Africa)

    Tesfaye, M

    2010-01-01

    Full Text Available In this paper, the tropospheric aerosol load morphological classification and its impact on temporal variation of visibility are investigated using a continuous 23-hour single channel CSIR-NLC mobile LIDAR backscatter measurement. The trajectory...

  7. Sea Floor Topography and Backscatter Intensity of the Historic Area Remediation Site

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set includes topography and backscatter intensity of the sea floor of the Historic Area Remediation Site (HARS), located offshore of New York and New...

  8. Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

    Science.gov (United States)

    Ansmann, A.; Bosenberg, J.

    1986-01-01

    A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present.

  9. Impact of sound attenuation by suspended sediment on ADCP backscatter calibrations

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Vermeulen, B.

    2012-01-01

    Although designed for velocity measurements, acoustic Doppler current profilers (ADCPs) are widely being used to monitor suspended particulate matter in rivers and in marine environments. To quantify mass concentrations of suspended matter, ADCP backscatter is generally calibrated with in situ

  10. Simrad em300 Backscatter imagery of Ni'ihau Island, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery extracted from gridded bathymetry of Ni'ihau Island, Hawaii, USA. These data provide almost complete coverage between 0 and 100 meters. The...

  11. GLAS/ICESat L1B Global Backscatter Data (HDF5) V033

    Data.gov (United States)

    National Aeronautics and Space Administration — The product includes full 532 nm and 1064 nm calibrated attenuated backscatter profiles at 5 times per second, and from 10 to -1 km, at 40 times per second. Also the...

  12. GLAS/ICESat L1B Global Backscatter Data V033

    Data.gov (United States)

    National Aeronautics and Space Administration — The product includes full 532 nm and 1064 nm calibrated attenuated backscatter profiles at 5 times per second, and from 10 to -1 km, at 40 times per second. Also the...

  13. Backscattered Helium Spectroscopy in the Helium Ion Microscope: Principles, Resolution and Applications

    NARCIS (Netherlands)

    van Gastel, Raoul; Hlawacek, G.; Dutta, S.; Poelsema, Bene

    2015-01-01

    We demonstrate the possibilities and limitations for microstructure characterization using backscattered particles from a sharply focused helium ion beam. The interaction of helium ions with matter enables the imaging, spectroscopic characterization, as well as the nanometer scale modification of

  14. Backscatter 0.5m TIFF Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography...

  15. Assessment of Multiple Delamination in Laminated Composites for Aircrafts using X-ray Backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Noh Yu [College of Medicine, Hanyang University, Cheonan (Korea, Republic of)

    2010-02-15

    A Compton X-ray backscatter technique has been developed to quantitatively assess impact damage in quasi-isotropic laminated composites made by a drop-weight tester. X-ray backscatter imaging system with a slit-type camera is constructed to obtain a cross-sectional profile of impact-damaged laminated composites from the electron-density variation of the cross section. A nonlinear scattering model based on Boltsman equation is introduced to compute Compton X-ray backscattering field for the defect assessment. An adaptive filter is also used to reduce noises from many sources including quantum noise and irregular distributions of fibers and matrix in composites. Delaminations masked or distorted by the first delamination are detected and characterized effectively by the Compton X-ray backscatter technique, both in width and location, by application of error minimization algorithm

  16. Polarimetric Backscattering Behavior of Ground Clutter at X, Ka, and W-band

    National Research Council Canada - National Science Library

    Gatesman, A. J; Goyette, T. M; Dickinson, J. C; Giles, R. H; Waldman, J; Sizemore, J; Chase, R. M; Nixon, W. E

    2005-01-01

    .... In addition to studying terrain backscatter as a function of surface roughness, the dependence on soil moisture content also was characterized by tailoring the dielectric constant of the scale models...

  17. CRED 1 meter resolution Reson 8101 multibeam backscatter data of Wake Island, West Central Pacific, 2007.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of Wake Island, West Central Pacific.These data provide coverage between 0 and 200m meters. The...

  18. P12 V ORBITING RADAR DERIVED BACKSCATTER CROSS SECTION V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of a VICAR2 format image of Venus large-angle radar backscatter cross section, from the side-looking mode of the Pioneer Venus radar mapper...

  19. Electrochemical incineration of wastes

    Science.gov (United States)

    Bhardwaj, R. C.; Sharma, D. K.; Bockris, J. Om.

    1990-08-01

    The novel technology of waste removal in space vehicles by electrochemical methods is presented to convert wastes into chemicals that can be eventually recycled. The important consideration for waste oxidation is to select a right kind of electrode (anode) material that should be stable under anodic conditions and also a poor electrocatalyst for oxygen and chlorine evolution. On the basis of long term electrolysis experiments on seven different electrodes and on the basis of total organic carbon reduced, two best electrodes were identified. The effect of redox ions on the electrolyte was studied. Though most of the experiments were done in mixtures of urine and waste, the experiments with redox couples involved 2.5 M sulfuric acid in order to avoid the precipitation of redox ions by urea. Two methods for long term electrolysis of waste were investigated: (1) the oxidation on Pt and lead dioxide electrodes using the galvanostatic methods; and (2) potentiostatic method on other electrodes. The advantage of the first method is the faster rate of oxidation. The chlorine evolution in the second method is ten times less then in the first. The accomplished research has shown that urine/feces mixtures can be oxidized to carbon dioxide and water, but current densities are low and must be improved. The perovskite and Ti4O7 coated with RuO2 are the best electrode materials found. Recent experiment with the redox agent improves the current density, however, sulphuric acid is required to keep the redox agent in solution to enhance oxidation effectively. It is desirable to reduce the use of acid and/or find substitutes.

  20. Backscattering in a helical liquid induced by Rashba spin-orbit coupling and electron interactions: Locality, symmetry, and cutoff aspects

    Science.gov (United States)

    Kharitonov, Maxim; Geissler, Florian; Trauzettel, Björn

    2017-10-01

    The combination of the time-reversal-symmetric single-particle backscattering field (commonly known as Rashba spin-orbit coupling) and nonbackscattering electron interactions is generally expected to produce inelastic backscattering in one-dimensional helical electron liquids at the edge of two-dimensional topological insulators, as theoretically predicted in a number of works. An opposite conclusion of absent backscattering was reached in a recent work [H.-Y. Xie et al., Phys. Rev. Lett. 116, 086603 (2016), 10.1103/PhysRevLett.116.086603] for the "local" model of the backscattering field and interactions. Motivated to resolve this potential controversy, in the present work, we study backscattering effects employing fermionic perturbation theory and considering quite general forms of the backscattering field and electron interactions. We discover that backscattering effects are crucially sensitive to the locality properties of the backscattering field and electron interactions, to the symmetry of the latter, as well as to the presence or absence of the cutoff of the electron spectrum. We find that backscattering is indeed absent under the following assumptions: (i) local backscattering field; (ii.a) local or (ii.b) SU(2)-symmetric interactions; (iii) absent cutoff of the edge-state spectrum. However, violation of any of these conditions leads to backscattering. This also reconciles with the results based on the bosonization technique. We calculate the associated backscattering current, establish its low-bias scaling behavior, and predict a crossover between two different scaling regimes. The main implication of our findings is that backscattering of some magnitude is inevitable in a real system, although it could be quite suppressed for nearly local backscattering field and interactions.

  1. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    David P. Bloomfield; Brian S. MacKenzie

    2006-05-01

    The Electrochemical Hydrogen Compressor EHC was evaluated against DOE applications for compressing hydrogen at automobile filling stations, in future hydrogen pipelines and as a commercial replacement for conventional diaphragm hydrogen compressors. It was also evaluated as a modular replacement for the compressors used in petrochemical refineries. If the EHC can be made inexpensive, reliable and long lived then it can satisfy all these applications save pipelines where the requirements for platinum catalyst exceeds the annual world production. The research performed did not completely investigate Molybdenum as a hydrogen anode or cathode, it did show that photoetched 316 stainless steel is inadequate for an EHC. It also showed that: molybdenum bipolar plates, photochemical etching processes, and Gortex Teflon seals are too costly for a commercial EHC. The use of carbon paper in combination with a perforated thin metal electrode demonstrated adequate anode support strength, but is suspect in promoting galvanic corrosion. The nature of the corrosion mechanisms are not well understood, but locally high potentials within the unit cell package are probably involved. The program produced a design with an extraordinary high cell pitch, and a very low part count. This is one of the promising aspects of the redesigned EHC. The development and successful demonstration of the hydraulic cathode is also important. The problem of corrosion resistant metal bipolar plates is vital to the development of an inexpensive, commercial PEM fuel cell. Our research suggests that there is more to the corrosion process in fuel cells and electrochemical compressors than simple, steady state, galvanic stability. It is an important area for scientific investigation. The experiments and analysis conducted lead to several recommended future research directions. First, we need a better understanding of the corrosion mechanisms involved. The diagnosis of experimental cells with titration to

  2. Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds

    Science.gov (United States)

    Buscombe, Daniel; Grams, Paul E.; Kaplinski, Matt A.

    2017-01-01

    Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

  3. Backscattering and Polarization Properties of Marine Particles -- Instrument Development and Field Work

    Science.gov (United States)

    2009-01-01

    Functions from 0.08 to 16 deg. for Randomly Shaped Terrigenous 1-21 μm Sediment Grains, Optics Express, v 17, n11, pp8805-8814. Y. C. Agrawal, E...Characterization of scattering from terrigenous size-sorted non-spherical particles; • Field observations of backscattering of marine particles;. WORK COMPLETED...shaped grains; I have completed some observations contrasting backscatter properties of random shaped sediment grains and polystyrene spheres. In

  4. Modeling the effects of laser-beam smoothing on filamentation and stimulated Brillouin backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R.L.; Kaiser, T.B.; Lasinski, B.F. [and others

    1996-06-01

    Using the three-dimensional code (F3D), the authors compute the filamentation and backscattering of laser light. The results show that filamentation can be controlled and stimulated Brillouin backscattering (SBBS) can be reduced by using random phase plates (RPP) and small f-numbers or smoothing by spectral dispersion (SSD) with large bandwidth. An interesting result is that, for uniform plasmas, the SBBS amplification takes place over several laser axial coherence lengths (coherence length = speckle length).

  5. Characterizing biogenous sediments using multibeam echosounder backscatter data - Estimating power law parameter utilizing various models

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Kodagali, V.N.

    ] for multibeam- Sca Beam system Sufficient acoustic pings were collected from each area when ship was stopped for sediment sampling Backscatter and geological sample data collections are made at ocanographically important sites from Southern Oceans. Agulhas... data collection was carried out at a station when ship was stopped for sediment core sampling, and this arrangement of data collection assured the statistical homogeneity ot backscatter data. MODELS USED We present two models, namely, the composite...

  6. Seafloor classification using acoustic backscatter echo-waveform - Artificial neural network applications

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Mahale, V.; Navelkar, G.S.; Desai, R.G.P.

    . This SOFM generated output space is further refined by Learning Vector Quantization (LVQ) an ANN supervised architecture in conjunction with the unsupervised SOFM architecture. LVQ employs reinforced supervised learning for fine-tuning of cluster.../ mixed and fine grain seafloor sediments (high to low backscatter strength and well compressed receiving pulse length). Though we have attempted to understand scattering behavior of the 33 kHz backscatter signal for different seafloor sediments...

  7. Integrating multibeam backscatter angular response, mosaic and bathymetry data for benthic habitat mapping.

    Directory of Open Access Journals (Sweden)

    Rozaimi Che Hasan

    Full Text Available Multibeam echosounders (MBES are increasingly becoming the tool of choice for marine habitat mapping applications. In turn, the rapid expansion of habitat mapping studies has resulted in a need for automated classification techniques to efficiently map benthic habitats, assess confidence in model outputs, and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth. However, studies that make use of the full range of MBES outputs within a single classification process are limited. We present an approach that integrates backscatter angular response with MBES bathymetry, backscatter mosaic and their derivatives in a classification process using a Random Forests (RF machine-learning algorithm to predict the distribution of benthic biological habitats. This approach includes a method of deriving statistical features from backscatter angular response curves created from MBES data collated within homogeneous regions of a backscatter mosaic. Using the RF algorithm we assess the relative importance of each variable in order to optimise the classification process and simplify models applied. The results showed that the inclusion of the angular response features in the classification process improved the accuracy of the final habitat maps from 88.5% to 93.6%. The RF algorithm identified bathymetry and the angular response mean as the two most important predictors. However, the highest classification rates were only obtained after incorporating additional features derived from bathymetry and the backscatter mosaic. The angular response features were found to be more important to the classification process compared to the backscatter mosaic features. This analysis indicates that integrating angular response information with bathymetry and the backscatter mosaic, along with

  8. O the First-Order Amplitude Statistics of Myocardial Ultrasonic Backscatter.

    Science.gov (United States)

    Clifford, Larry Arthur

    Improved understanding of ultrasonic backscatter, particularly of its statistical behavior in the presence of disease, could enhance tissue characterization methods. Historically it has been assumed that the first-order envelope statistics of ultrasonic myocardial backscatter are best described by the Rayleigh probability distribution function (PDF); this assumption has been challenged frequently in recent years, however, the relative goodness-of-fit (GOF) of competing PDFs to actual data has not been tested. This research compares the abilities of five PDFs (the Rayleigh, the Rician, the lognormal, the Nakagami-m, and the K) to describe high-frequency (2.5-15 MHz) ultrasonic backscatter from in vivo canine myocardium, in vitro human myocardium, in vivo (intraoperative) human myocardium, in vivo blood pool, tissue phantoms, and computer simulations. Ordinal GOF rankings of myocardial data from a wide variety of sources show that only in a small minority of cases is the envelope of backscatter from myocardium Rayleigh-distributed, or other than K-distributed. On the other hand, backscatter from sources expected to be Rayleigh-scattering (such as tissue phantom and blood pool) is approximately Rayleigh -distributed, confirming that non-Rayleighness is not simply a system artifact. Furthermore, signal statistics are not found to be sensitive indicators of disease under clinical operating conditions. Analysis of the influence of pulse shape on the backscatter amplitude density using classical Random Walk and probability techniques, followed by application of Monte Carlo methods to the resulting expressions, shows that backscatter statistics depend both on pulse characteristics (in a manner which can be functionally described) and on the heart's collagen microstructure (in a manner which can be approximately modeled). The observed first-order amplitude statistics of myocardial backscatter are thus characterized with new specificity and a theoretical frame offered within

  9. Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds

    Science.gov (United States)

    Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

    2017-10-01

    Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

  10. MEASURING THE PARTICULATE BACKSCATTERING OF INLAND WATERS: A COMPARISON OF TECHNIQUES

    Directory of Open Access Journals (Sweden)

    G. Campbell

    2012-07-01

    Full Text Available The objective of this work was to examine whether the standard particulate backscattering IOP (Inherent Optical Properties measurement method could be simplified. IOP measurements are essential for parameterising several forms of algorithms used to estimate water quality parameters from airborne and satellite images. Field measurements of the backscattering IOPs are more difficult to make than absorption measurements as correction of the raw Hydroscat-6 backscattering sensor observations is required to allow for the systematic errors associated with the water and water quality parameter absorption. The standard approach involves making simultaneous measurement of the absorption and attenuation of the water with an absorption and attenuation meter (ac-9 or making assumptions about the particulate backscattering probability. Recently, a number of papers have been published that use an alternative method to retrieve the particulate backscattering spectrum by using laboratory measured absorption values and in situ spectroradiometric observations. The alternative method inverts a model of reflectance iteratively using non-linear least squares fitting to solve for the particulate backscattering at 532 nm (bbp0(532 and the particulate backscattering spectral slope (γ. In this paper, eleven observations made at Burdekin Falls Dam, Australia are used to compare the alternative reflectance method to the conventional corrected Hydroscat-6 observations. Assessment of the alternative reflectance method showed that the result of the inversions were highly dependent on the starting conditions. To overcome this limitation, Particle Swarm Optimisation, a stochastic search technique which includes a random element in the search approach, was used. It was found that when compared to the conventionally corrected Hydroscat-6 observations, the alternative reflectance method underestimated bbp0(532 by approximately 50% and overestimated γ by approximately 40

  11. Mapping Wetlands in Zambia Using Seasonal Backscatter Signatures Derived from ENVISAT ASAR Time Series

    Directory of Open Access Journals (Sweden)

    Stefan Schlaffer

    2016-05-01

    Full Text Available Wetlands are considered a challenging environment for mapping approaches based on Synthetic Aperture Radar (SAR data due to their often complex internal structures and the diverse backscattering mechanisms caused by vegetation, soil moisture and flood dynamics contributing to the resulting imagery. In this study, a time series of >100 SAR images acquired by ENVISAT during a time period of ca. two years over the Kafue River basin in Zambia was compared to water heights derived from radar altimetry and surface soil moisture from a reanalysis dataset. The backscatter time series were analyzed using a harmonic model to characterize the seasonality in C-band backscatter caused by the interaction of flood and soil moisture dynamics. As a result, characteristic seasonal signatures could be derived for permanent water bodies, seasonal open water, persistently flooded vegetation and seasonally flooded vegetation. Furthermore, the analysis showed that the influence of local incidence angle could be accounted for by a linear shift in backscatter averaged over time, even in wetland areas where the dominant scattering mechanism can change depending on the season. The retrieved harmonic model parameters were then used in an unsupervised classification to detect wetland backscattering classes at the regional scale. A total area of 7800 km2 corresponding to 7.6% of the study area was classified as either one of the wetland backscattering classes. The results demonstrate the value of seasonality parameters extracted from C-band SAR time series for wetland mapping.

  12. Pixelated VLC-Backscattering for Self-Charging Indoor IoT Devices

    Science.gov (United States)

    Shao, Sihua; Khreishah, Abdallah; Elgala, Hany

    2017-01-01

    Visible light communication (VLC) backscatter has been proposed as a wireless access option for Internet of Things (IoT). However, the throughput of the state-of-the-art VLC backscatter is limited by simple single-carrier pulsed modulation scheme, such as on-off keying (OOK). In this paper, a novel pixelated VLC backscatter is proposed and implemented to overcome the channel capacity limitation. In particular, multiple smaller VLC backscatters, switching on or off, are integrated to generate multi-level signals, which enables the usage of more advanced modulation schemes than OOK. Based on experimental results, rate adaptation at different communication distances can be employed to enhance the achievable data rate. Compared to OOK, the data rate can be tripled when 8-PAM is used at 2 meters. In general, $n$-fold throughput enhancement is realized by utilizing $n$ smaller VLC backscatters while incurring negligible additional energy using the same device space as that of a single large backscatter.

  13. Waterfall notch-filtering for restoration of acoustic backscatter records from Admiralty Bay, Antarctica

    Science.gov (United States)

    Fonseca, Luciano; Hung, Edson Mintsu; Neto, Arthur Ayres; Magrani, Fábio José Guedes

    2017-08-01

    A series of multibeam sonar surveys were conducted from 2009 to 2013 around Admiralty Bay, Shetland Islands, Antarctica. These surveys provided a detailed bathymetric model that helped understand and characterize the bottom geology of this remote area. Unfortunately, the acoustic backscatter records registered during these bathymetric surveys were heavily contaminated with noise and motion artifacts. These artifacts persisted in the backscatter records despite the fact that the proper acquisition geometry and the necessary offsets and delays were applied during the survey and in post-processing. These noisy backscatter records were very difficult to interpret and to correlate with gravity-core samples acquired in the same area. In order to address this issue, a directional notch-filter was applied to the backscatter waterfall in the along-track direction. The proposed filter provided better estimates for the backscatter strength of each sample by considerably reducing residual motion artifacts. The restoration of individual samples was possible since the waterfall frame of reference preserves the acquisition geometry. Then, a remote seafloor characterization procedure based on an acoustic model inversion was applied to the restored backscatter samples, generating remote estimates of acoustic impedance. These remote estimates were compared to Multi Sensor Core Logger measurements of acoustic impedance obtained from gravity core samples. The remote estimates and the Core Logger measurements of acoustic impedance were comparable when the shallow seafloor was homogeneous. The proposed waterfall notch-filtering approach can be applied to any sonar record, provided that we know the system ping-rate and sampling frequency.

  14. Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars

    Science.gov (United States)

    Lamarche, Geoffroy; Lurton, Xavier

    2017-05-01

    Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group (Geohab.org) has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working group, and a synopsis of the BSWG Guidelines and Recommendations to date. The paper includes (1) an overview of the current status in sensors and techniques available in seafloor backscatter data from multibeam sonars; (2) the presentation of the BSWG structure and results; (3) recommendations to operators, end-users, sonar manufacturers, and software developers using sonar backscatter for seafloor-mapping applications, for best practice methods and approaches for data acquisition and processing; and (4) a discussion on the development needs for future systems and data processing. We propose for the first time a nomenclature of backscatter processing levels that affords a means to accurately and efficiently describe the data processing status, and to facilitate comparisons of final products from various origins.

  15. Modeling and analysis of ultrasound backscattering by spherical aggregates and rouleaux of red blood cells.

    Science.gov (United States)

    Teh, B G; Cloutier, G

    2000-01-01

    The present study concerns the modeling and analysis of ultrasound backscattering by red blood cell (RBC) aggregates, which under pathological conditions play a significant role in the rheology of blood within human vessels. A theoretical model based on the convolution between a tissue matrix and a point spread function, representing, respectively, the RBC aggregates and the characteristics of the ultrasound system, was used to examine the influence of the scatterer shape and size on the backscattered power. Both scatterers in the form of clumps of RBC aggregates and rouleaux were modeled. For all simulations, the hematocrit was kept constant at 10%, the ultrasound frequency was 10 MHz, the insonification angle was varied from 0 to 90 degrees , and the scatterer size (diameter for clumps and length for rouleaux) ranged from 4 mum to 120 mum. Under Rayleigh scattering by assuming a Poisson distribution of scatterers in space, the ultrasound backscattered power increased linearly with the particle volume. For non-Rayleigh scatterers, the intensity of the echoes diminished as the scatterer volume increased, with the exception of rouleaux at an angle of 90 degrees . As expected, the backscattered power was angularly dependent for anisotropic particles (rouleaux). The ultrasound backscattered power did not always increase with the size of the aggregates, especially when they were no longer Rayleigh scatterers. In the case of rouleaux, the anisotropy of the backscattered power is emphasized in the non-Rayleigh region.

  16. Distance effects in electrochemical micromachining

    Science.gov (United States)

    Xu, Lizhong; Pan, Yue; Zhao, Chuanjun

    2016-09-01

    Considering exponential dependence of currents on double-layer voltage and the feedback effect of the electrolyte resistance, a distance effect in electrochemical micromachining is found, namely that both time constant and double-layer voltage depend on the separation of electrodes. The double-layer voltage is the real voltage used in processing. Under DC voltage, the apparent voltages between two electrodes are constant for different separations, but the real voltages change with the separations. Small separations exert substantial effects on the real voltages. Accordingly, a DC-voltage small-separation electrochemical micromachining technique was proposed. The double-layer voltage drops sharply as the small separation increases. Thus, the electrochemical reactions are confined to electrode regions in very close proximity even under DC voltage. The machining precision can be significantly enhanced by reducing the voltage and separation between electrodes. With this technique, the machining of conducting materials with submicrometre precision was achieved.

  17. Microarray of programmable electrochemically active elements

    DEFF Research Database (Denmark)

    McCaskill, John; Maeke, Thomas; Straczek, Lukas

    Possible applications of the MICREAgents Dock, a two dimensional array of programmable electrochemically active elements, to Alife.......Possible applications of the MICREAgents Dock, a two dimensional array of programmable electrochemically active elements, to Alife....

  18. Electrochemical Behaviour of Environmentally Friendly Inhibitor of ...

    African Journals Online (AJOL)

    Electrochemical Behaviour of Environmentally Friendly Inhibitor of Aloe Secundiflora Extract in Corrosion Control of Carbon Steel in Soft Water Media. ... corrosion control in neutral and aerated soft water solutions have been investigated using electrochemical impedance spectroscopy and Tafel polarization techniques.

  19. Effect of cold deformation on the electrochemical behaviour of 304L stainless steel in contaminated sulfuric acid environment

    Science.gov (United States)

    Luo, Hong; Su, Huaizhi; Ying, Guobing; Dong, Chaofang; Li, Xiaogang

    2017-12-01

    The effect of cold deformation on the microstructure and electrochemical corrosion behaviour of 304L stainless steel in contaminated sulfuric acid solutions (simulated proton exchange membrane fuel cells environments) were evaluated using electron backscatter diffraction analyses, electrochemical measurements, and surface analyses. The internal microstructure,including the grain sizes, angles of the grain boundaries, low coincidence site lattice boundaries, and phase transformations, was changed due to the cold deformation. No noticeable modifications of the pitting corrosion potential were observed during the various deformations, except for a slight enhancement in the passive current density with an increase in the deformation. The CrO3 and metal Ni species in the passive film were investigated after deformation. After heavy deformation (greater than 60%), nickel oxides were detected. Moreover, the Cr/Fe and O2-/OH- ratios in the passive film were higher before deformation, and they decreased with an increase in the deformation level.

  20. The Sources That Give Rise to the Backscattering and Its Spectral Variation

    Science.gov (United States)

    Zhang, X.; Gray, D. J.; McKee, D.

    2016-02-01

    While the color of the ocean mainly results from the spectral absorption by particle assemblage in the ocean, it is the volume scattering, particularly, the backscattering that reflect the light, thus making the color observable. In addition, the backscattering and its spectral variations also carry information about the particles that cannot be retreived from the absorption alone. While the backscattering coefficients and its spectral signature have been empirically related to a variety of biogeochemical quantities, such as PIC, POC, SPM, or mean sizes of particulates, theoretical studies show the small particles, most in the operationally dissolved domain, are the main contributor. Thus, the question remains as to the sources of backscattering and its spectral variations, the answer to which is not only important to the sicence of ocean color but can also lead to improvements in its algorithm development and data interpretation. The challenges in addressing this question include, among many, the accurate measurements of backscattering coefficients, the interpretation of angular VSFs, and simulation of scattering by non-spherical and -homogeneous particles. Overcoming some of these challenges, we have measured the spectral VSFs in three coastal waters around US and during the SABOR experiment in North Atlantic ocean. The spectral backscattering coefficients were derived from the VSFs in a varietry of water types, ranging from turbit estuarine to open ocean, from mineral dominant tidal zone to algal bloom. We also applied the inversion technique to partition the measured VSFs into contributions by particle populations of a wide ranges of sizes and composition that are representative of oceanic particles, living and nonliving. This inversion approach allows us to examine the relative importance of various particle populations to the backscattering. Furthermore, we applied forward modeling using non-spherical particles to simulate the spectral backscattering by

  1. A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available A poleward-progressing 630 nm optical feature is observed between approximately 0100 UT and 0230 UT (0400 MLT to 0530 MLT by a meridian-scanning photometer (MSP located at Ny Ålesund, Svalbard. Simultaneous coherent HF radar measurements indicate a region of poleward-expanding backscatter with rapid sunward plasma flow velocity along the MSP meridian. Spatial maps of the backscatter indicate a stationary backscatter feature aligned obliquely with respect to the MSP meridian, which produces an impression of poleward-expansion as the MSP progresses to later MLT. Two interpretations of the observations are possible, depending on whether the arc system is considered to move (time-dependent or to be stationary in time and apparent motion is produced as the MSP meridian rotates underneath it (time-independent. The first interpretation is as a poleward motion of an east-west aligned auroral arc. In this case the appearance of the region of backscatter is not associated with the optical feature, though the velocities within it are enhanced when the two are co-located. The second interpretation is as a polar arc or theta aurora, common features of the polar cap under the prevailing IMF northwards conditions. In this case the backscatter appears as an approximately 150 km wide region adjacent to the optical arc. In both interpretations the luminosity of the optical feature appears related to the magnitude of the plasma flow velocity. The optical features presented here do not generate appreciable HF coherent backscatter, and are only identifiable in the backscatter data as a modification of the flow by the arc electrodynamics.

  2. Monte Carlo investigation of backscatter point spread function for x-ray imaging examinations

    Science.gov (United States)

    Xiong, Zhenyu; Vijayan, Sarath; Rudin, Stephen; Bednarek, Daniel R.

    2017-03-01

    X-ray imaging examinations, especially complex interventions, may result in relatively high doses to the patient's skin inducing skin injuries. A method was developed to determine the skin-dose distribution for non-uniform x-ray beams by convolving the backscatter point-spread-function (PSF) with the primary-dose distribution to generate the backscatter distribution that, when added to the primary dose, gives the total-dose distribution. This technique was incorporated in the dose-tracking system (DTS), which provides a real-time color-coded 3D-mapping of skin dose during fluoroscopic procedures. The aim of this work is to investigate the variation of the backscatter PSF with different parameters. A backscatter PSF of a 1-mm x-ray beam was generated by EGSnrc Monte-Carlo code for different x-ray beam energies, different soft-tissue thickness above bone, different bone thickness and different entrance-beam angles, as well as for different locations on the SK-150 anthropomorphic head phantom. The results show a reduction of the peak scatter to primary dose ratio of 48% when X-ray beam voltage is increased from 40 keV to 120 keV. The backscatter dose was reduced when bone was beneath the soft tissue layer and this reduction increased with thinner soft tissue and thicker bone layers. The backscatter factor increased about 21% as the angle of incidence of the beam with the entrance surface decreased from 90° (perpendicular) to 30°. The backscatter PSF differed for different locations on the SK-150 phantom by up to 15%. The results of this study can be used to improve the accuracy of dose calculation when using PSF convolution in the DTS.

  3. Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought.

    Science.gov (United States)

    Frolking, Steve; Hagen, Stephen; Braswell, Bobby; Milliman, Tom; Herrick, Christina; Peterson, Seth; Roberts, Dar; Keller, Michael; Palace, Michael

    2017-01-01

    Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon's vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999-2009, and low morning backscatter persisted for 2006-2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts.

  4. Materials for electrochemical device safety

    Science.gov (United States)

    Vissers, Daniel R.; Amine, Khalil; Thackeray, Michael M.; Kahaian, Arthur J.; Johnson, Christopher S.

    2015-04-07

    An electrochemical device includes a thermally-triggered intumescent material or a gas-triggered intumescent material. Such devices prevent or minimize short circuits in a device that could lead to thermal run-away. Such devices may include batteries or supercapacitors.

  5. Electrochemical Machining Removes Deep Obstructions

    Science.gov (United States)

    Catania, Mark J.

    1987-01-01

    Electrochemical machining (ECM) is effective way of removing obstructing material between two deep holes supposed to intersect but do not because of misalignment of drilling tools. ECM makes it possible to rework costly castings otherwise scrapped. Method fast even for tough or hard alloys and complicated three-dimensional shapes.

  6. New Materials for Electrochemical Cells.

    Science.gov (United States)

    1987-06-20

    34Electrochemical extraction of lithium ,0 from LiMn 24", Mat. Res. Bull. 19 179 (1984) 𔃾 , (48) J. Fontcuberta , J. Rodriguez, M. Pernet, G. Longworth and...J.B. Goodenough, "Structural and magnetic characterization of the lithiated iron oxide LixFe 304", J. Appl. Phys. 59 1918 (1986) (49) J. Fontcuberta

  7. Electrolytes for magnesium electrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Burrell, Anthony K.; Sa, Niya; Proffit, Danielle Lee; Lipson, Albert; Liao, Chen; Vaughey, John T.; Ingram, Brian J.

    2017-07-04

    An electrochemical cell includes a high voltage cathode configured to operate at 1.5 volts or greater; an anode including Mg.sup.0; and an electrolyte including an ether solvent and a magnesium salt; wherein: a concentration of the magnesium salt in the ether is 1 M or greater.

  8. Some properties of electrochemical nanostructures†

    Indian Academy of Sciences (India)

    Administrator

    tional to the potential of zero charge (pzc), this entails that the pzc of the nanowires is shifted to substantially higher values; of the metals investi- gated, this effect is largest for gold, where the shift is more than 1 eV. Consequently, monoatomic nanowires in electrochemical aqueous solutions carry a negative excess charge ...

  9. Electrochemical Induced Calcium Phosphate Precipitation

    NARCIS (Netherlands)

    Lei, Yang; Song, Bingnan; Weijden, van der Renata D.; Saakes, M.; Buisman, Cees J.N.

    2017-01-01

    Phosphorus (P) is an essential nutrient for living organisms and cannot be replaced or substituted. In this paper, we present a simple yet efficient membrane free electrochemical system for P removal and recovery as calcium phosphate (CaP). This method relies on in situ formation of hydroxide

  10. Graphene-based electrochemical supercapacitors

    Indian Academy of Sciences (India)

    Graphenes prepared by three different methods have been investigated as electrode materials in electrochemical supercapacitors. The samples prepared by exfoliation of graphitic oxide and by the transformation of nanodiamond exhibit high specific capacitance in aq. H2SO4, the value reaching up to 117 F/g. By using an ...

  11. Electrochemical method for transferring graphene

    DEFF Research Database (Denmark)

    2015-01-01

    The present application discloses a method for separating a graphene-support layer laminate from a conducting substrate-graphene-support layer laminate, using a gentle, controllable electrochemical method. In this way, substrates which are fragile, expensive or difficult to manufacture can be used...... - and even re-used - without damage or destruction of the substrate or the graphene....

  12. Synthesis, photophysical, electrochemical and electroluminescence ...

    Indian Academy of Sciences (India)

    ... of Chemical Sciences; Volume 129; Issue 9. Synthesis, photophysical, electrochemical and electroluminescence studies of red emitting phosphorescent Ir(III) heteroleptic complexes. FARMAN ALI PABITRA K NAYAK N PERIASAMY NEERAJ AGARWAL. Regular Aricle Volume 129 Issue 9 September 2017 pp 1391-1398 ...

  13. Stormwater disinfection using Electrochemical oxidation

    OpenAIRE

    WENJUN FENG

    2017-01-01

    This thesis demonstrates that electrochemical oxidation can be a promising stormwater disinfection technique to achieve regulatory water re-uses targets. It discusses the implications for the practical implementation of the technology and identifies areas for future research in regards to optimisation of the technology

  14. Electrochemical Genosensing of Circulating Biomarkers

    Science.gov (United States)

    Campuzano, Susana; Yáñez-Sedeño, Paloma; Pingarrón, José Manuel

    2017-01-01

    Management and prognosis of diseases requires the measurement in non- or minimally invasively collected samples of specific circulating biomarkers, consisting of any measurable or observable factors in patients that indicate normal or disease-related biological processes or responses to therapy. Therefore, on-site, fast and accurate determination of these low abundance circulating biomarkers in scarcely treated body fluids is of great interest for health monitoring and biological applications. In this field, electrochemical DNA sensors (or genosensors) have demonstrated to be interesting alternatives to more complex conventional strategies. Currently, electrochemical genosensors are considered very promising analytical tools for this purpose due to their fast response, low cost, high sensitivity, compatibility with microfabrication technology and simple operation mode which makes them compatible with point-of-care (POC) testing. In this review, the relevance and current challenges of the determination of circulating biomarkers related to relevant diseases (cancer, bacterial and viral infections and neurodegenerative diseases) are briefly discussed. An overview of the electrochemical nucleic acid–based strategies developed in the last five years for this purpose is given to show to both familiar and non-expert readers the great potential of these methodologies for circulating biomarker determination. After highlighting the main features of the reported electrochemical genosensing strategies through the critical discussion of selected examples, a conclusions section points out the still existing challenges and future directions in this field. PMID:28420103

  15. Polarized gamma-rays with laser-Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S. [Electrotechnical Lab., Ibaraki (Japan)] [and others

    1995-12-31

    Polarized gamma-rays were generated through laser-Compton backscattering (LCS) of a conventional Nd:YAG laser with electrons circulating in the electron storage ring TERAS at Electrotechnical Laboratory. We measured the energy, the energy spread, and the yield of the gamma-rays to characterize our gamma-ray source. The gamma-ray energy can be varied by changing the energy of the electrons circulating the storage ring. In our case, the energy of electrons in the storage ring were varied its energy from 200 to 750 MeV. Consequently, we observed gamma-ray energies of 1 to 10 MeV with 1064 run laser photons. Furthermore, the gamma-ray energy was extended to 20 MeV by using the 2nd harmonic of the Nd:YAG laser. This shows a good agreement with theoretical calculation. The gamma-ray energy spread was also measured to be 1% FWHM for -1 MeV gamma-rays and to be 4% FWHM for 10 MeV gamma-rays with a narrow collimator that defined the scattering cone. The gamma-ray yield was 47.2 photons/mA/W/s. This value is consistent with a rough estimation of 59.5 photons/mA/W/s derived from theory. Furthermore, we tried to use these gamma-rays for a nuclear fluorescence experiment. If we use a polarized laser beam, we can easily obtain polarized gamma-rays. Elastically scattered photons from {sup 208} Pb were clearly measured with the linearly polarized gamma-rays, and we could assign the parity of J=1 states in the nucleus. We should emphasize that the polarized gamma-ray from LCS is quit useful in this field, because we can use highly, almost completely, polarized gamma-rays. We also use the LCS gamma-rays to measure the photon absorption coefficients. In near future, we will try to generate a circular polarized gamma-ray. We also have a plan to use an FEL, because it can produce intense laser photons in the same geometric configuration as the LCS facility.

  16. Solar Backscatter UV (SBUV total ozone and profile algorithm

    Directory of Open Access Journals (Sweden)

    P. K. Bhartia

    2013-10-01

    Full Text Available We describe the algorithm that has been applied to develop a 42 yr record of total ozone and ozone profiles from eight Solar Backscatter UV (SBUV instruments launched on NASA and NOAA satellites since April 1970. The Version 8 (V8 algorithm was released more than a decade ago and has been in use since then at NOAA to produce their operational ozone products. The current algorithm (V8.6 is basically the same as V8, except for updates to instrument calibration, incorporation of new ozone absorption cross-sections, and new ozone and cloud height climatologies. Since the V8 algorithm has been optimized for deriving monthly zonal mean (MZM anomalies for ozone assessment and model comparisons, our emphasis in this paper is primarily on characterizing the sources of errors that are relevant for such studies. When data are analyzed this way the effect of some errors, such as vertical smoothing of short-term variability, and noise due to clouds and aerosols diminish in importance, while the importance of others, such as errors due to vertical smoothing of the quasi-biennial oscillation (QBO and other periodic and aperiodic variations, become more important. With V8.6 zonal mean data we now provide smoothing kernels that can be used to compare anomalies in SBUV profile and partial ozone columns with models. In this paper we show how to use these kernels to compare SBUV data with Microwave Limb Sounder (MLS ozone profiles. These kernels are particularly useful for comparisons in the lower stratosphere where SBUV profiles have poor vertical resolution but partial column ozone values have high accuracy. We also provide our best estimate of the smoothing errors associated with SBUV MZM profiles. Since smoothing errors are the largest source of uncertainty in these profiles, they can be treated as error bars in deriving interannual variability and trends using SBUV data and for comparing with other measurements. In the V8 and V8.6 algorithms we derive total

  17. Vertical Resolved Dust Mass Concentration and Backscatter Coefficient Retrieval of Asian Dust Plume Using Quartz Raman Channel in Lidar Measurements

    OpenAIRE

    Noh Young M.; Mueller Detlef; Shin Sungkyun

    2016-01-01

    In this work, we present a method for estimating vertical resolved mass concentration of dust immersed in Asian dust plume using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profiles of the quartz backscatter coefficient. Since the Raman backscatter coefficient was connected with the Raman backscatter differential cross section a...

  18. Quantitative Analysis of Venus Radar Backscatter Data in ArcGIS

    Science.gov (United States)

    Long, S. M.; Grosfils, E. B.

    2005-01-01

    Ongoing mapping of the Ganiki Planitia (V14) quadrangle of Venus and definition of material units has involved an integrated but qualitative analysis of Magellan radar backscatter images and topography using standard geomorphological mapping techniques. However, such analyses do not take full advantage of the quantitative information contained within the images. Analysis of the backscatter coefficient allows a much more rigorous statistical comparison between mapped units, permitting first order selfsimilarity tests of geographically separated materials assigned identical geomorphological labels. Such analyses cannot be performed directly on pixel (DN) values from Magellan backscatter images, because the pixels are scaled to the Muhleman law for radar echoes on Venus and are not corrected for latitudinal variations in incidence angle. Therefore, DN values must be converted based on pixel latitude back to their backscatter coefficient values before accurate statistical analysis can occur. Here we present a method for performing the conversions and analysis of Magellan backscatter data using commonly available ArcGIS software and illustrate the advantages of the process for geological mapping.

  19. Coherent Backscattering and Opposition Effects Observed in Some Atmosphereless Bodies of the Solar System

    Science.gov (United States)

    Dlugach, Zh. M.; Mishchenko, M. I.

    2013-01-01

    The results of photometric and polarimetric observations carried out for some bright atmosphere-less bodies of the Solar system near the zero phase angle reveal the simultaneous existence of two spectacular optical phenomena, the so-called brightness and polarization opposition effects. In a number of studies, these phenomena were explained by the influence of coherent backscattering. However, in general, the interference concept of coherent backscattering can be used only in the case where the particles are in the far-field zones of each other, i.e., when the scattering medium is rather rarefied. Because of this, it is important to prove rigorously and to demonstrate that the coherent backscattering effect may also exist in densely packed scattering media like regolith surface layers of celestial bodies. From the results of the computer modeling performed with the use of numerically exact solutions of the macroscopic Maxwell equations for discrete random media with different packing densities of particles, we studied the origin and evolution of all the opposition phenomena predicted by the coherent backscattering theory for low-packing-density media. It has been shown that the predictions of this theory remain valid for rather high-packing densities of particles that are typical, in particular, of regolith surfaces of the Solar system bodies. The results allow us to conclude that both opposition effects observed simultaneously in some high-albedo atmosphereless bodies of the Solar system are caused precisely by coherent backscattering of solar light in the regolith layers composed of microscopic particles.

  20. User expectations for multibeam echo sounders backscatter strength data-looking back into the future

    Science.gov (United States)

    Lucieer, Vanessa; Roche, Marc; Degrendele, Koen; Malik, Mashkoor; Dolan, Margaret; Lamarche, Geoffroy

    2017-05-01

    With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing capabilities, navigation, and graphic display devices, have improved the resolution and particularly the dynamic range available to sonar and processing software manufacturers. Alongside these improvements the expectations of what the data can deliver has also grown. In this paper, we identify these user-expectations and explore how MBES backscatter is utilized by different communities involved in marine seabed research at present, and the aspirations that these communities have for the data in the future. The results presented here are based on a user survey conducted by the GeoHab (Marine Geological and Biological Habitat Mapping) association. This paper summarises the different processing procedures employed to extract useful information from MBES backscatter data and the various intentions for which the user community collect the data. We show how a range of backscatter output products are generated from the different processing procedures, and how these results are taken up by different scientific disciplines, and also identify common constraints in handling MBES BS data. Finally, we outline our expectations for the future of this unique and important data source for seafloor mapping and characterisation.

  1. Modification of Spalart-Allmaras model with consideration of turbulence energy backscatter using velocity helicity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yangwei, E-mail: liuyangwei@126.com [Group 404, National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics, School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Lu, Lipeng [Group 404, National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics, School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Laboratoire International Associe, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Fang, Le [Laboratoire de Mecanique des Fluides et d' Acoustique, Ecole Centrale de Lyon, 69134 (France); Laboratoire International Associe, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Gao, Feng [Group 404, National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics, School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

    2011-06-13

    The correlation between the velocity helicity and the energy backscatter is proved in a DNS case of 256{sup 3}-grid homogeneous isotropic decaying turbulence. The helicity is then proposed to be employed to improve turbulence models and SGS models. Then Spalart-Allmaras turbulence model (SA) is modified with the helicity to take account of the energy backscatter, which is significant in the region of corner separation in compressors. By comparing the numerical results with experiments, it can be concluded that the modification for SA model with helicity can appropriately represent the energy backscatter, and greatly improves the predictive accuracy for simulating the corner separation flow in compressors. -- Highlights: → We study the relativity between the velocity helicity and the energy backscatter. → Spalart-Allmaras turbulence model is modified with the velocity helicity. → The modified model is employed to simulate corner separation in compressor cascade. → The modification can greatly improve the accuracy for predicting corner separation. → The helicity can represent the energy backscatter in turbulence and SGS models.

  2. Electrochemical synthesis of nanostructured materials for electrochemical energy conversion and storage.

    Science.gov (United States)

    Li, Gao-Ren; Xu, Han; Lu, Xue-Feng; Feng, Jin-Xian; Tong, Ye-Xiang; Su, Cheng-Yong

    2013-05-21

    Electrochemical synthesis represents a highly efficient method for the fabrication of nanostructured energy materials, and various nanostructures, such as nanorods, nanowires, nanotubes, nanosheets, dendritic nanostructures, and composite nanostructures, can be easily fabricated with advantages of low cost, low synthetic temperature, high purity, simplicity, and environmental friendliness. The electrochemical synthesis, characterization, and application of electrochemical energy nanomaterials have advanced greatly in the past few decades, allowing an increasing understanding of nanostructure-property-performance relationships. Herein, we highlight some recent progress in the electrochemical synthesis of electrochemical energy materials with the assistance of additives and templates in solution or grafted onto metal or conductive polymer supports, with special attention to the effects on surface morphologies, structures and, more importantly, electrochemical performance. The methodology for preparing novel electrochemical energy nanomaterials and their potential applications has been summarized. Finally, we outline our personal perspectives on the electrochemical synthesis and applications of electrochemical energy nanomaterials.

  3. Monte Carlo modeling of cavity imaging in pure iron using back-scatter electron scanning microscopy

    Science.gov (United States)

    Yan, Qiang; Gigax, Jonathan; Chen, Di; Garner, F. A.; Shao, Lin

    2016-11-01

    Backscattered electrons (BSE) in a scanning electron microscope (SEM) can produce images of subsurface cavity distributions as a nondestructive characterization technique. Monte Carlo simulations were performed to understand the mechanism of void imaging and to identify key parameters in optimizing void resolution. The modeling explores an iron target of different thicknesses, electron beams of different energies, beam sizes, and scan pitch, evaluated for voids of different sizes and depths below the surface. The results show that the void image contrast is primarily caused by discontinuity of energy spectra of backscattered electrons, due to increased outward path lengths for those electrons which penetrate voids and are backscattered at deeper depths. Size resolution of voids at specific depths, and maximum detection depth of specific voids sizes are derived as a function of electron beam energy. The results are important for image optimization and data extraction.

  4. The complementary use of electron backscatter diffraction and ion channelling imaging for the characterization of nanotwins

    DEFF Research Database (Denmark)

    Alimadadi, Hossein; da Silva Fanta, Alice Bastos; Pantleon, Karen

    2013-01-01

    On the example of electrodeposited nickel films, it is shown that unique information on twins with dimensions on the nanoscale can be obtained by suitable combination of ion channelling imaging and electron backscatter diffraction analysis, whereas both (routine) single techniques cannot meet...... the requirements for analysis of these films. High‐resolution electron backscatter diffraction is inadequate for full characterization of nanotwins, but image quality maps obtained from electron backscatter diffraction at least yield a qualitative estimation of the location and number of nanotwins. Complementing...... this information with ion channelling imaging provides more representative insights into the microstructure, because it supplements the quantitative investigation of the number and width of twin lamellae with additional crystallographic orientation analysis provided by EBSD. To this end, two methods for adjusting...

  5. Improving high-intensity focused ultrasound beam imaging via a backscattering suppression algorithm

    Science.gov (United States)

    Matsui, Kazuhiro; Azuma, Takashi; Fujiwara, Keisuke; Takeuchi, Hideki; Itani, Kazunori; Wang, Junchen; Iwahashi, Toshihide; Kobayashi, Etsuko; Sakuma, Ichiro

    2017-05-01

    In an ultrasound-guided high-intensity focused ultrasound (HIFU) device, a HIFU focal error may be observed in an ultrasound pulse-echo image due to the difference between the HIFU and imaging beam aberrations occurring in the heterogeneous propagative medium, which was verified by simulating the ultrasound beams passing through an abdominal wall. The HIFU focal error could reduce the accuracy of targeting the HIFU focal spot at a tumor. To measure the focal error, HIFU beam imaging based on backscattered wave reconstruction can be used; however, its image qualities deteriorate due to inhomogeneous backscattering. Hence, we proposed a novel backscattering suppression algorithm based on an inverse problem approach to retrieve HIFU beam components. The proposed algorithm was validated in ex vivo experiments in conjunction with focal spot shifts and beam width variations, demonstrating the clear improvement of HIFU beam imaging quality.

  6. Monitoring Everglades freshwater marsh water level using L-band synthetic aperture radar backscatter

    Science.gov (United States)

    Kim, Jin-Woo; Lu, Zhong; Jones, John W.; Shum, C.K.; Lee, Hyongki; Jia, Yuanyuan

    2014-01-01

    The Florida Everglades plays a significant role in controlling floods, improving water quality, supporting ecosystems, and maintaining biodiversity in south Florida. Adaptive restoration and management of the Everglades requires the best information possible regarding wetland hydrology. We developed a new and innovative approach to quantify spatial and temporal variations in wetland water levels within the Everglades, Florida. We observed high correlations between water level measured at in situ gages and L-band SAR backscatter coefficients in the freshwater marsh, though C-band SAR backscatter has no close relationship with water level. Here we illustrate the complementarity of SAR backscatter coefficient differencing and interferometry (InSAR) for improved estimation of high spatial resolution water level variations in the Everglades. This technique has a certain limitation in applying to swamp forests with dense vegetation cover, but we conclude that this new method is promising in future applications to wetland hydrology research.

  7. Comparison of measurements and theory for backscatter from bare and snow-covered saline ice

    Science.gov (United States)

    Bredow, Jonathan W.; Gogineni, Sivaprasad

    1990-01-01

    C-band radar backscatter measurements were made on artificially grown sea ice during the winters of 1987-1988 and 1988-1989. These measurements were made on smooth, rough, and snow-covered saline ice. The measured sigma-deg(theta) of smooth saline ice (rms height less than 0.05 cm) disagreed with small perturbation method (SPM) surface scattering predictions. Using physical parameters of the ice in a simple layer model, it us shown that this discrepancy can be explained by scattering from beneath the surface. A thin (7-cm) dry snow cover had a significant influence on backscatter from the smooth ice sheet. This influence was due to scattering from particles within the snow, and can be predicted by a commonly used empirical layer model for snow. The results of backscatter measurements of a moderately rough saline ice sheet were found to agree with SPM predictions.

  8. Measurements and analysis of acoustic backscattering by elastic cubes and irregular polyhedra

    DEFF Research Database (Denmark)

    Thorne, P D; Sun, S; Zhang, J

    1997-01-01

    Underwater acoustic studies of backscattering by submerged targets have generally focused on bodies with spherical and cylindrical symmetry. However, there are interests in scattering by objects which may be characterized by more angular features, with surfaces that tend to be composed of facets...... and edges. To investigate the scattering properties of such bodies, the backscattering by a number of elastic cubes, and irregularly shaped polyhedra, have been studied. Data were collected by measuring the band limited impulse response of the scatterers, using a broadband transducer, which operated...... as a transceiver, both transmitting and receiving signals. To present the scattering measurements nondimensionally a form function definition has been employed to normalize the backscattered signals. The normalized frequency has been expressed as ka, where k is the acoustic wave number, and a is a characteristic...

  9. A composite L-band HH radar backscattering model for coniferous forest stands

    Science.gov (United States)

    Sun, Guoquing; Simonett, David S.

    1988-01-01

    The radar backscattering model developed by Richards et al. (1987), has been improved and further tested in this research. The trunk term may now be calculated from the exact solution to the electromagnetic wave equations instead of the corner reflector equation. Rough surface models have been introduced into the radar model, so that the forward reflectance and the backscattering from the ground surface are now calculated from the same model and, thus, are consistent. The number of trees in an individual pixel is assumed to be Poisson distributed, with tree height in a stand log-normally distributed. The simulated results show that the match of backscattering coefficients for eight forest stands between SIR-B image data and the simulated results are satisfying, and that the trunk term now seems to be convincingly established as the dominant term in the L-band HH radar return from coniferous forest stands.

  10. Development of a global model for atmospheric backscatter at CO2 wavelengths

    Science.gov (United States)

    Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

    1986-01-01

    The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season.

  11. Development of global model for atmospheric backscatter at CO2 wavelengths

    Science.gov (United States)

    Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

    1985-01-01

    The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere.

  12. Probing insect backscatter cross-section and melanization using kHz optical remote detection system

    Science.gov (United States)

    Gebru, Alem K.; Brydegaard, Mikkel; Rohwer, Erich; Neethling, Pieter

    2016-09-01

    kHz optical remote sensing system is implemented to determine melanization and backscatter cross-section in the near infrared (NIR) and shortwave infrared (SWIR) in situ. It is shown that backscatter cross-section in the SWIR is insensitive to melanization and absolute melanization can be derived from the ratio of backscatter cross-section in two bands (SWIR/NIR). We have shown that insects reflect more strongly in the SWIR as compared to NIR and Visible (VIS) in accordance with previous findings. This is illustrated using three different insects (Snow white moth (spilosoma genus), Fox moth (Macrothylacia) and Leather beetle (Odontotaenius genus)) and it is shown that the reflectance of the Leather beetle in the VIS and NIR is more affected by melanization as compared with snow white moth.

  13. Performance of low-power RFID tags based on modulated backscattering

    Science.gov (United States)

    Mhanna, Zeinab; Sibille, Alain; Contreras, Richard

    2017-02-01

    Ultra Wideband (UWB) modulated backscattering (MBS) passive Radio-Frequency IDentification (RFID) systems provide a promising solution to overcome many limitations of current narrowband RFID devices. This work addresses the performance of such systems from the point of view of the radio channel between the readers and the tags. Such systems will likely combine several readers, in order to provide both the detection and localization of tags operating in MBS. Two successive measurements campaigns have been carried out in an indoor reference scenario environment. The first is intended to verify the methods and serves as a way to validate the RFID backscattering measurement setup. The second represents a real use case for RFID application and allows one to quantitatively analyze the path loss of the backscattering propagation channel. xml:lang="fr"

  14. Changes in backscatter of liver tissue due to thermal coagulation induced by focused ultrasound.

    Science.gov (United States)

    Shishitani, Takashi; Matsuzawa, Ryo; Yoshizawa, Shin; Umemura, Shin-ichiro

    2013-08-01

    Ultrasonic imaging has advantages in its self-consistency in guiding and monitoring ultrasonic treatment such as high-intensity focused ultrasound (HIFU) treatment. Changes in ultrasonic backscatter of tissues due to HIFU treatment have been observed, but their mechanism is still under discussion. In this paper, ultrasonic backscatter of excised and degassed porcine liver tissue was observed before and after HIFU exposure using a diagnostic scanner, and its acoustic impedance was mapped using an ultrasonic microscope. The histology of its pathological specimen was also observed using an optical microscope. The observed decrease in backscatter intensity due to HIFU exposure was consistent with a spatial Fourier analysis of the histology, which also showed changes due to the exposure. The observed increase in acoustic impedance due to the exposure was also consistent with the histological change assuming that the increase was primarily caused by the increase in the concentration of hepatic cells.

  15. Practical analytical backscatter error bars for elastic one-component lidar inversion algorithm.

    Science.gov (United States)

    Rocadenbosch, Francesc; Reba, M Nadzri Md; Sicard, Michaël; Comerón, Adolfo

    2010-06-10

    We present an analytical formulation to compute the total-backscatter range-dependent error bars from the well-known Klett's elastic-lidar inversion algorithm. A combined error-propagation and statistical formulation approach is used to assess inversion errors in response to the following error sources: observation noise (i.e., signal-to-noise ratio) in the reception channel, the user's uncertainty in the backscatter calibration, and in the (range-dependent) total extinction-to-backscatter ratio provided. The method is validated using a Monte Carlo procedure, where the error bars are computed by inversion of a large population of noisy generated lidar signals, for total optical depths tau < or = 5 and typical user uncertainties, all of which yield a practical tool to compute the sought-after error bars.

  16. Calculation of backscatter factors for diagnostic radiology using Monte Carlo methods

    Energy Technology Data Exchange (ETDEWEB)

    Petoussi-Henss, N.; Zankl, M.; Drexler, G.; Panzer, W.; Regulla, D. [GSF-National Research Center for Environment and Health, Institute of Radiation Protection, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    1998-08-01

    Backscatter factors were determined for x-ray beams relevant to diagnostic radiology using Monte Carlo methods. The phantom size considered most suitable for calibration of dosimeters is a cuboid of 30x30cm{sup 2} front surface and 15 cm depth. This phantom size also provides a good approximation to adult patients. Three different media were studied: water, PMMA and ICRU tissue; the source geometry was a point source with varying field size and source-to-phantom distance. The variations of the backscatter factor with phantom medium and field geometry were examined. From the obtained data, a set of backscatter factors was selected and proposed for adoption as a standard set for the calibration of dosimeters to be used to measure diagnostic reference doses. (author)

  17. Direct detection of near-surface faults by migration of back-scattered surface waves

    KAUST Repository

    Yu, Han

    2014-08-05

    We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps are to isolate the back-scattered surface waves, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. A deconvolution filter derived from the data can be used to collapse a dispersive arrival into a non-dispersive event. Results with synthetic data and field records validate the feasibility of this method. Applying this method to USArray data or passively recorded exploration data might open new opportunities in mapping tectonic features over the extent of the array.

  18. Laser-based air data system for aircraft control using Raman and elastic backscatter for the measurement of temperature, density, pressure, moisture, and particle backscatter coefficient.

    Science.gov (United States)

    Fraczek, Michael; Behrendt, Andreas; Schmitt, Nikolaus

    2012-01-10

    Flight safety in all weather conditions demands exact and reliable determination of flight-critical air parameters. Air speed, temperature, density, and pressure are essential for aircraft control. Conventional air data systems can be impacted by probe failure caused by mechanical damage from hail, volcanic ash, and icing. While optical air speed measurement methods have been discussed elsewhere, in this paper, a new concept for optically measuring the air temperature, density, pressure, moisture, and particle backscatter is presented, being independent on assumptions on the atmospheric state and eliminating the drawbacks of conventional aircraft probes by providing a different measurement principle. The concept is based on a laser emitting laser pulses into the atmosphere through a window and detecting the signals backscattered from a fixed region just outside the disturbed area of the fuselage flows. With four receiver channels, different spectral portions of the backscattered light are extracted. The measurement principle of air temperature and density is based on extracting two signals out of the rotational Raman (RR) backscatter signal of air molecules. For measuring the water vapor mixing ratio-and thus the density of the moist air-a water vapor Raman channel is included. The fourth channel serves to detect the elastic backscatter signal, which is essential for extending the measurements into clouds. This channel contributes to the detection of aerosols, which is interesting for developing a future volcanic ash warning system for aircraft. Detailed and realistic optimization and performance calculations have been performed based on the parameters of a first prototype of such a measurement system. The impact and correction of systematic error sources, such as solar background at daytime and elastic signal cross talk appearing in optically dense clouds, have been investigated. The results of the simulations show the high potential of the proposed system for

  19. Quantitative evaluation of myocardial fibrosis by cardiac integrated backscatter analysis in Kawasaki disease.

    Science.gov (United States)

    Xie, Lijian; Wang, Renjian; Huang, Min; Zhang, Yongwei; Shen, Jie; Xiao, Tingting

    2016-01-12

    Kawasaki disease is an acute, systemic vasculitis that affects the coronary arteries. However, the relationship between myocardial fibrosis and Kawasaki disease has been completely unknown until now. We aimed to provide quantitative information about myocardial fibrosis using cardiac integrated backscatter in Han race Kawasaki disease patients. Ninety Kawasaki disease patients and 90 healthy control subjects were recruited. Based on Kawasaki disease status, the patients were categorized into 3 groups: acute, subacute, and convalescence phase. Based on coronary artery status, the Kawasaki disease patients were categorized into 3 groups: without coronary artery lesions, with coronary artery dilation, and with coronary artery aneurysms. All subjects underwent two-dimensional and Doppler examinations to measure clinical echocardiographic parameters. Myocardial fibrosis was detected with calibrated integrated backscatter imaging. Left ventricle systolic functions were normal in both the Kawasaki disease and control participants. The myocardial calibrated integrated backscatter values of the left ventricles of the acute (p Kawasaki disease patients were significantly greater than those of the healthy controls. The left ventricle myocardial calibrated integrated backscatter values were significantly smaller in the Kawasaki disease patients without coronary artery lesions than in the Kawasaki disease patients with coronary artery dilations and coronary artery aneurysms in different phases. The left ventricle myocardial calibrated integrated backscatter results were positively correlated with coronary artery status in the acute (r = 0.331, p Kawasaki disease. Our findings may suggest that myocardial fibrosis occurs during early episodes of Kawasaki disease given uncertainties that exist regarding correlations of calibrated integrated backscatter and myocardial fibrosis.

  20. Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers

    Science.gov (United States)

    Kotthaus, Simone; O'Connor, Ewan; Münkel, Christoph; Charlton-Perez, Cristina; Haeffelin, Martial; Gabey, Andrew M.; Grimmond, C. Sue B.

    2016-08-01

    Ceilometer lidars are used for cloud base height detection, to probe aerosol layers in the atmosphere (e.g. detection of elevated layers of Saharan dust or volcanic ash), and to examine boundary layer dynamics. Sensor optics and acquisition algorithms can strongly influence the observed attenuated backscatter profiles; therefore, physical interpretation of the profiles requires careful application of corrections. This study addresses the widely deployed Vaisala CL31 ceilometer. Attenuated backscatter profiles are studied to evaluate the impact of both the hardware generation and firmware version. In response to this work and discussion within the CL31/TOPROF user community (TOPROF, European COST Action aiming to harmonise ground-based remote sensing networks across Europe), Vaisala released new firmware (versions 1.72 and 2.03) for the CL31 sensors. These firmware versions are tested against previous versions, showing that several artificial features introduced by the data processing have been removed. Hence, it is recommended to use this recent firmware for analysing attenuated backscatter profiles. To allow for consistent processing of historic data, correction procedures have been developed that account for artefacts detected in data collected with older firmware. Furthermore, a procedure is proposed to determine and account for the instrument-related background signal from electronic and optical components. This is necessary for using attenuated backscatter observations from any CL31 ceilometer. Recommendations are made for the processing of attenuated backscatter observed with Vaisala CL31 sensors, including the estimation of noise which is not provided in the standard CL31 output. After taking these aspects into account, attenuated backscatter profiles from Vaisala CL31 ceilometers are considered capable of providing valuable information for a range of applications including atmospheric boundary layer studies, detection of elevated aerosol layers, and model

  1. Cavitation inception by the backscattering of pressure waves from a bubble interface

    Energy Technology Data Exchange (ETDEWEB)

    Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp; Tanaka, Moe [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531 (Japan)

    2015-10-28

    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  2. Long Wavelength SAR Backscatter Modelling Trends as a Consequence of the Emergent Properties of Tree Populations

    Directory of Open Access Journals (Sweden)

    Matthew Brolly

    2014-07-01

    Full Text Available This study describes the novel use of a macroecological plant and forest structure model in conjunction with a Radiative Transfer (RT model to better understand interactions between microwaves and forest canopies. Trends predicted by the RT model, resulting from interactions with mixed age, mono and multi species forests, are analysed in comparison to those predicted using a simplistic structure based scattering model. This model relates backscatter to scatterer cross sectional or volume specifications, dependent on the size. The Spatially Explicit Reiterative Algorithm (SERA model is used to provide a widely varied tree size distribution while maintaining allometric consistency to produce a natural-like forest representation. The RT model is parameterised using structural information from SERA and microwave backscatter simulations are used to analyse the impact of changes to the forest stand. Results show that the slope of the saturation curve observed in the Synthetic Aperture Radar (SAR backscatter-biomass relationship is sensitive to thinning and therefore forest basal area. Due to similarities displayed between the results of the RT and simplistic model, it is determined that forest SAR backscatter behaviour at long microwave wavelengths may be described generally using equations related to total stem volume and basal area. The nature of these equations is such that they describe saturating behaviour of forests in the absence of attenuation in comparable fashion to the trends exhibited using the RT model. Both modelled backscatter trends predict a   relationship to forest basal area from an early age when forest volume is increasing. When this is not the case, it is assumed to be a result of attenuation of the dominant stem-ground interaction due to the presence of excessive numbers of stems. This work shows how forest growth models can be successfully incorporated into existing independent scattering models and reveals, through the RT

  3. Electrochemical treatment of liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    1996-10-01

    Electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This activity consists of five major tasks: (1) evaluation of different electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale size reactor, and (5) analysis and evaluation of testing data. The development program team is comprised of individuals from federal, academic, and private industry. Work is being carried out in DOE, academic, and private industrial laboratories.

  4. Electrochemical promotion of catalytic reactions

    Science.gov (United States)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  5. Electrochemical synthesis of multisegmented nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kok, Kuan-Ying; Ng, Inn-Khuan; Saidin, Nur Ubaidah [Malaysian Nuclear Agency, Bangi, 43000 Kajang (Malaysia)

    2012-11-27

    Electrochemical deposition has emerged as a promising route for nanostructure fabrication in recent years due to the many inherent advantages it possesses. This study focuses on the synthesis of high-aspect-ratio multisegmented Au/Ni nanowires using template-directed sequential electrochemical deposition techniques. By selectively removing the Ni segments in the nanowires, high-yield of pure gold nanorods of predetermined lengths was obtained. Alternatively, the sacrificial Ni segments in the nanowires can be galvanically displaced with Bi and Te to form barbells structures with Bi{sub x}Te{sub y} nanotubes attached to neighbouring gold segments. Detailed studies on the nanostructures obtained were carried out using various microscopy, diffraction and probebased techniques for structural, morphological and chemical characterizations.

  6. Electrochemical sensing carcinogens in beverages

    CERN Document Server

    Zia, Asif Iqbal

    2016-01-01

    This book describes a robust, low-cost electrochemical sensing system that is able to detect hormones and phthalates – the most ubiquitous endocrine disruptor compounds – in beverages and is sufficiently flexible to be readily coupled with any existing chemical or biochemical sensing system. A novel type of silicon substrate-based smart interdigital transducer, developed using MEMS semiconductor fabrication technology, is employed in conjunction with electrochemical impedance spectroscopy to allow real-time detection and analysis. Furthermore, the presented interdigital capacitive sensor design offers a sufficient penetration depth of the fringing electric field to permit bulk sample testing. The authors address all aspects of the development of the system and fully explain its benefits. The book will be of wide interest to engineers, scientists, and researchers working in the fields of physical electrochemistry and biochemistry at the undergraduate, postgraduate, and research levels. It will also be high...

  7. Electrochemical routes for industrial synthesis

    OpenAIRE

    Sequeira, C. A. C.; Santos, D. M. F.

    2009-01-01

    This review examines the reasons for increasing interest towards electrolyses by the chemical industry, reviews the electrochemical industries as most of them now exist, and provides a status report on the key technological advances which are occurring to meet present and future needs. Classical industries like those of chloroalkali, aluminium, p-aminophenol, adiponitrile, ethylene glycol, anthraquinone, perfluorinated products, glyoxylic acid and L-cysteine are initially covered. Considering...

  8. Electro-chemical capacitor developments

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, T.C.; Kramer, W.E.; Wright, R.B. [Lockheed-Martin Idaho Technologies Co. (United States)

    1996-12-31

    A number of promising materials have been identified for use as electrochemical capacitor (ultracapacitor) electrodes. These include carbon, conducting polymers, metal nitrides, and metal oxides in combinations with aqueous and organic electrolytes. Carbon materials (particles, fibers, foams, and composites) have been investigated more than other active electrode materials for a number of reasons. Carbon can be easily activated and formed into electrodes exhibiting high specific capacity (100-300F/g) and low electronic resistivity (0.01ohm-cm). (author)

  9. Electrochemical Design of Optical Nanoantennas

    Directory of Open Access Journals (Sweden)

    Vasilchenko V.E.

    2015-01-01

    Full Text Available Electrochemical techniques for fabricating tapered gold nanoantennas (tips are discussed. In the paper, the tunable design of nanoantennas is demonstrated. Tip parameters such as a tip apex curvature, mesoscopic morphology, aspect ratio and enhancement factor can be varied with etching electrolyte and applied voltage. The low-cost method makes tipehnahced optical spectroscopy and microscopy feasible for routine optical measurements beyond the diffraction limit.

  10. Experimental results and Monte Carlo simulations of a landmine localization device using the neutron backscattering method

    CERN Document Server

    Datema, C P; Eijk, C W E

    2002-01-01

    Experiments were carried out to investigate the possible use of neutron backscattering for the detection of landmines buried in the soil. Several landmines, buried in a sand-pit, were positively identified. A series of Monte Carlo simulations were performed to study the complexity of the neutron backscattering process and to optimize the geometry of a future prototype. The results of these simulations indicate that this method shows great potential for the detection of non-metallic landmines (with a plastic casing), for which so far no reliable method has been found.

  11. The laser-backscattering equations and their application to the study of the atmospheric structure

    CERN Document Server

    Castrejon, R; Castrejon, J; Morales, A

    2002-01-01

    In this work a method for interpreting backscattering signals acquired by a lidar is described. The method is based on the elastic scattering of laser radiation due to gases and particles suspended in the atmosphere (bulk effects). We propose a space-time diagram which helps to evaluate the arguments of the equation that serves to calculate the lidar signal in terms of the backscattering coefficient. We describe how the system detects gradients on this coefficient, along the laser optical path. To illustrate the method, we present some typical lidar results obtained in the neighborhood of Mexico City. (Author)

  12. High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz

    Science.gov (United States)

    Huang, Chih-Chung

    2010-10-01

    There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r2) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm-1 at 30 MHz to 0.47 Nepers mm-1 at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was maximal around a

  13. Computation of Nonlinear Backscattering Using a High-Order Numerical Method

    Science.gov (United States)

    Fibich, G.; Ilan, B.; Tsynkov, S.

    2001-01-01

    The nonlinear Schrodinger equation (NLS) is the standard model for propagation of intense laser beams in Kerr media. The NLS is derived from the nonlinear Helmholtz equation (NLH) by employing the paraxial approximation and neglecting the backscattered waves. In this study we use a fourth-order finite-difference method supplemented by special two-way artificial boundary conditions (ABCs) to solve the NLH as a boundary value problem. Our numerical methodology allows for a direct comparison of the NLH and NLS models and for an accurate quantitative assessment of the backscattered signal.

  14. Boundary effects on backscattering by a solid aluminum cylinder: experiment and finite element model comparisons (L).

    Science.gov (United States)

    La Follett, Jon R; Williams, Kevin L; Marston, Philip L

    2011-08-01

    Backscattering of sound by a solid aluminum cylinder was measured in the free field and with the cylinder near a flat surface. The target was suspended just below the surface of a water tank to simulate some aspects of backscattering when resting on the seabed. Measurements were compared with predictions made by an approximate hybrid approach based on multiple two-dimensional finite element calculations and the use of images. Many of the spectral features present in the tank data were present in the model. Comparing numerical model predictions with experimental data serves to build credibility for the modeling approach and can assist in developing insight into the underlying physical processes.

  15. High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chih-Chung, E-mail: j648816n@ms23.hinet.ne [Department of Electrical Engineering, Fu Jen Catholic University, Taipei, Taiwan (China)

    2010-10-07

    There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r{sup 2}) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm{sup -1} at 30 MHz to 0.47 Nepers mm{sup -1} at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was

  16. [Backscattering Characteristics of Machining Surfaces and Retrieval of Surface Multi-Parameters].

    Science.gov (United States)

    Tao, Hui-rong; Zhang, Fu-min; Qu, Xing-hua

    2015-07-01

    For no cooperation target laser ranging, the backscattering properties of the long-range and real machined surfaces are uncertain which seriously affect the ranging accuracy. It is an important bottleneck restricting the development of no cooperation ranging technology. In this paper, the backscattering characteristics of three typical machining surfaces (vertidal milling processing method, horizontal milling processing method and plain grinding processing method) under the infrared laser irradiation with 1550 nm were measured. The relation between the surface nachining texture, incident azimuth, roughness and the backscattering distribution were analyzed and the reasons for different processing methods specific backscattering field formed were explored. The experimental results show that the distribution of backscattering spectra is greatly affected by the machined processing methods. Incident angle and roughness have regularity effect on the actual rough surface of each mode. To be able to get enough backscattering, knowing the surface texture direction and the roughness of machined metal is essential for the optimization of the non-contact measurement program in industry. On this basis, a method based on an artificial neural network (ANN) and genetic algorithm (GA), is proposed to retrieve the surface multi-parameters of the machined metal. The generalized regression neural network (GRNN) was investigated and used in this application for the backscattering modeling. A genetic algorithm was used to retrieve the multi-parameters of incident azimuth angle, roughness and processing methods of machined metal sur face. Another processing method of sample (planer processing method) was used to validate data. The final results demonstrated that the method presented was efficient in parameters retrieval tasks. This model can accurately distinguish processing methods and the relative error of incident azimuth and roughness is 1.21% and 1.03%, respectively. The inversion

  17. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: Spin coating vs electrochemical activation

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Montelongo, J., E-mail: jacobo.hernandez@uam.es [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gallach, D.; Naveas, N.; Torres-Costa, V. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Climent-Font, A. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid, Madrid 28049 (Spain); García-Ruiz, J.P. [Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049 (Spain); Manso-Silvan, M. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering. - Highlights: • Proposed cyclic methods produce specific morphologies and CaP phases in biocomposites. • The brushite phase is favored in the biocomposite produced by Cyclic Spin Coating. • The hydroxyapatite phase is favored in the biocomposite produced by Cyclic Electrochemical Activation. • The Ca/P atomic ratio of hydroxyapatite was validated by elastic backscattering spectroscopy. • Cells grown showed morphological and

  18. Attenuation of Bragg backscattering of electromagnetic waves from density fluctuations near the region of polarization degeneracy in magnetoactive plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gospodchikov, E. D., E-mail: egos@appl.sci-nnov.ru; Khusainov, T. A.; Shalashov, A. G. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2016-08-15

    Specific features of Bragg backscattering under conditions of strong polarization degeneracy near the cutoff surface in an anisotropic medium are studied analytically and numerically. It is shown that the linear interaction of normal waves can substantially affect wave scattering by suppressing the amplification of Bragg backscattering near the cutoff region in the case of weak coupling between normal waves.

  19. Comparison of CO2 Lidar Backscatter with Particle Size Distribution and GOES-7 Data in Hurricane Juliette

    Science.gov (United States)

    Jarzembski, Maurice; Pueschel, R. F.; Srivastava, Vandana; McCaul, E. W., Jr.; Cutten, Dean R.; Jedlovec, Gary J.; Atkinson, R. J.

    1999-01-01

    Backscatter measurements using 9.1 and 10.6 micron continuous wave lidars were obtained along with particle size distributions in 1995 Hurricane Juliette at altitude approximately 11.7 km. Agreement between lidar backscatter and cloud particle size distribution was excellent. Measurements also correlated well with concurrent GOES-7 infrared images of cloud top height.

  20. Effects of soil moisture and water depth on ERS SAR backscatter measurements from an Alaskan wetland complex

    Science.gov (United States)

    Eric S. Kasischke; Laura L. Bourgeau-Chavez; Allison R. Rober; Kevin H. Wyatt; James M. Waddington; Merritt R. Turetsky

    2009-01-01

    We conducted a preliminary investigation of the response of ERS C-band SAR backscatter to variations in soil moisture and surface inundation in wetlands of interior Alaska. Data were collected from 5 wetlands over a three-week period in 2007. Results showed a positive correlation between backscatter and soil moisture in sites dominated by herbaceous vegetation cover (r...

  1. Management of processes of electrochemical dimensional processing

    Science.gov (United States)

    Akhmetov, I. D.; Zakirova, A. R.; Sadykov, Z. B.

    2017-09-01

    In different industries a lot high-precision parts are produced from hard-processed scarce materials. Forming such details can only be acting during non-contact processing, or a minimum of effort, and doable by the use, for example, of electro-chemical processing. At the present stage of development of metal working processes are important management issues electrochemical machining and its automation. This article provides some indicators and factors of electrochemical machining process.

  2. Electrochemical components employing polysiloxane-derived binders

    Science.gov (United States)

    Delnick, Frank M.

    2013-06-11

    A processed polysiloxane resin binder for use in electrochemical components and the method for fabricating components with the binder. The binder comprises processed polysiloxane resin that is partially oxidized and retains some of its methyl groups following partial oxidation. The binder is suitable for use in electrodes of various types, separators in electrochemical devices, primary lithium batteries, electrolytic capacitors, electrochemical capacitors, fuel cells and sensors.

  3. Electrochemical ion separation in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Spoerke, Erik David; Ihlefeld, Jon; Waldrip, Karen; Wheeler, Jill S.; Brown-Shaklee, Harlan James; Small, Leo J.; Wheeler, David R.

    2017-12-19

    A purification method that uses ion-selective ceramics to electrochemically filter waste products from a molten salt. The electrochemical method uses ion-conducting ceramics that are selective for the molten salt cations desired in the final purified melt, and selective against any contaminant ions. The method can be integrated into a slightly modified version of the electrochemical framework currently used in pyroprocessing of nuclear wastes.

  4. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  5. Working electrode holder and electrochemical cell

    DEFF Research Database (Denmark)

    2016-01-01

    The present disclosure relates to a holder for a test object, more specifically to a holder for measuring electrochemical properties of the test object. One embodiment relates to a working electrode holder for measuring electrochemical properties of a front surface of a test object in a liquid...... in the bottom surface and configured for passage of said liquid, such that liquid is able to pass onto the electrically contacted front surface. The holder may be used in an electrochemical cell....

  6. Experimental Determination of Dual-Wavelength Mie Lidar Geometric form Factor Combining Side-Scatter and Back-Scatter Signals

    Directory of Open Access Journals (Sweden)

    Wang Zhenzhu

    2016-01-01

    Full Text Available In theory, lidar overlap factor can be derived from the difference between the particle backscatter coefficient retrieved from lidar elastic signal without overlap correction and the actual particle backscatter coefficient, which can be obtained by other measured techniques. The side-scatter signal using a CCD camera is testified to be a powerful tool to detect the particle backscatter coefficient in near ground layer during night time. In experiment, by combining side-scatter and backscatter signals the geometric form factor for vertically-pointing Mie lidar in 532 nm channel is determined successfully, which is corrected by an iteration algorithm combining the retrieved particle backscatter coefficient using CCD sidescatter method and Fernald method. In this study, the method will be expanded to 1064 nm channel in dual-wavelength Mie lidar during routine campaigns. The experimental results in different atmosphere conditions demonstrated that the method present in this study is available in practice.

  7. Electrochemical atomic force microscopy: In situ monitoring of electrochemical processes

    Science.gov (United States)

    Reggente, Melania; Passeri, Daniele; Rossi, Marco; Tamburri, Emanuela; Terranova, Maria Letizia

    2017-08-01

    The in-situ electrodeposition of polyaniline (PANI), one of the most attractive conducting polymers (CP), has been monitored performing electrochemical atomic force microscopy (EC-AFM) experiments. The electropolymerization of PANI on a Pt working electrode has been observed performing cyclic voltammetry experiments and controlling the evolution of current flowing through the electrode surface, together with a standard AFM image. The working principle and the potentialities of this emerging technique are briefly reviewed and factors limiting the studying of the in-situ electrosynthesis of organic compounds discussed.

  8. Lidar monitoring of regions of intense backscatter with poorly defined boundaries

    Science.gov (United States)

    Vladimir A. Kovalev; Alexander Petkov; Cyle Wold; WeiMin Hao

    2011-01-01

    The upper height of a region of intense backscatter with a poorly defined boundary between this region and a region of clear air above it is found as the maximal height where aerosol heterogeneity is detectable, that is, where it can be discriminated from noise. The theoretical basis behind the retrieval technique and the corresponding lidar-data-processing procedures...

  9. Backscattering analysis of high frequency ultrasonic imaging for ultrasound-guided breast biopsy

    Science.gov (United States)

    Cummins, Thomas; Akiyama, Takahiro; Lee, Changyang; Martin, Sue E.; Shung, K. Kirk

    2017-03-01

    A new ultrasound-guided breast biopsy technique is proposed. The technique utilizes conventional ultrasound guidance coupled with a high frequency embedded ultrasound array located within the biopsy needle to improve the accuracy in breast cancer diagnosis.1 The array within the needle is intended to be used to detect micro- calcifications indicative of early breast cancers such as ductal carcinoma in situ (DCIS). Backscattering analysis has the potential to characterize tissues to improve localization of lesions. This paper describes initial results of the application of backscattering analysis of breast biopsy tissue specimens and shows the usefulness of high frequency ultrasound for the new biopsy related technique. Ultrasound echoes of ex-vivo breast biopsy tissue specimens were acquired by using a single-element transducer with a bandwidth from 41 MHz to 88 MHz utilizing a UBM methodology, and the backscattering coefficients were calculated. These values as well as B-mode image data were mapped in 2D and matched with each pathology image for the identification of tissue type for the comparison to the pathology images corresponding to each plane. Microcalcifications were significantly distinguished from normal tissue. Adenocarcinoma was also successfully differentiated from adipose tissue. These results indicate that backscattering analysis is able to quantitatively distinguish tissues into normal and abnormal, which should help radiologists locate abnormal areas during the proposed ultrasound-guided breast biopsy with high frequency ultrasound.

  10. Free-solution, label-free molecular interactions studied by back-scattering interferometry

    DEFF Research Database (Denmark)

    Bornhop, D.J.; Latham, J.C.; Kussrow, A.

    2007-01-01

    Free-solution, label-free molecular interactions were investigated with back-scattering interferometry in a simple optical train composed of a helium-neon laser, a microfluidic channel, and a position sensor. Molecular binding interactions between proteins, ions and protein, and small molecules...

  11. Dominant Channel Occupancy for Wi-Fi Backscatter Uplink in Industrial Internet of Things

    Directory of Open Access Journals (Sweden)

    Jung-Hyok Kwon

    2016-12-01

    Full Text Available This paper presents a dominant channel occupancy (DCO mechanism for the Wi-Fi backscatter uplink in the industrial Internet of things (IIoT. The DCO provides high-priority channel access and reliable burst transmission to the Wi-Fi backscatter devices, thereby enabling the Wi-Fi backscatter tag to deliver its tag information to the Wi-Fi reader without interference from neighboring legacy Wi-Fi devices to guarantee the timeliness and reliability of the IIoT system. For the former, we consider three types of medium access control (MAC configurations: “carrier sense multiple access with collision avoidance (CSMA/CA starting with short inter-frame space (SIFS”, “freezing of the backoff period”, and “reduced CWmin.” In addition, the DCO uses the SIFS between burst packets to guarantee reliable burst transmission. To verify the effectiveness of DCO and determine a proper value for MAC parameters, we conduct experimental simulations under IEEE 802.11n PHY/MAC environments. The simulation results show that the reduced CWmin has the most significant effect on the channel occupancy. The Wi-Fi backscatter devices achieve much higher throughput than the separate cases when two or more configurations are used simultaneously. Moreover, the results exhibit that the use of SIFS between consecutive packets supports reliable burst transmission regardless of the transmission of the legacy Wi-Fi devices in the vicinity.

  12. A compact Compton backscatter X-ray source for mammography and coronary angiography

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, D.C.; Kinross-Wright, J.M.; Weber, M.E.; Volz, S.K. [Los Alamos National Lab., NM (United States); Gierman, S.M.; Hayes, K.; Vernon, W. [Univ. of California, San Diego, CA (United States); Goldstein, D.J. [Univ. of California, Los Angeles, CA (United States)

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objective is to generate a large flux of tunable, monochromatic x-rays for use in mammography and coronary angiography. The approach is based on Compton backscattering of an ultraviolet solid-state laser beam against the high-brightness 20-MeV electron beams from a compact linear accelerator. The direct Compton backscatter approach failed to produce a large flux of x-rays due to the low photon flux of the scattering solid-state laser. The authors have modified the design of a compact x-ray source to the new Compton backscattering geometry with use of a regenerative amplifier free-electron laser. They have successfully demonstrated the production of a large flux of infrared photons and a high-brightness electron beam focused in both dimensions for performing Compton backscattering in a regenerative amplifier geometry.

  13. Sensitivity of Multi-Source SAR Backscatter to Changes in Forest Aboveground Biomass

    Directory of Open Access Journals (Sweden)

    Wenli Huang

    2015-07-01

    Full Text Available Accurate estimates of forest aboveground biomass (AGB after anthropogenic disturbance could reduce uncertainties in the carbon budget of terrestrial ecosystems and provide critical information to policy makers. Yet, the loss of carbon due to forest disturbance and the gain from post-disturbance recovery have not been sufficiently assessed. In this study, a sensitivity analysis was first conducted to investigate: (1 the influence of incidence angle and soil moisture on Synthetic Aperture Radar (SAR backscatter; (2 the feasibility of cross-image normalization between multi-temporal and multi-sensor SAR data; and (3 the possibility of applying normalized backscatter data to detect forest biomass changes. An empirical model was used to reduce incidence angle effects, followed by cross-image normalization procedure to lessen soil moisture effect. Changes in forest biomass at medium spatial resolution (100 m were mapped using both spaceborne and airborne SAR data. Results indicate that (1 the effect of incidence angle on SAR backscatter could be reduced to less than 1 dB by the correction model for airborne SAR data; (2 over 50% of the changes in SAR backscatter due to soil moisture could be eliminated by the cross-image normalization procedure; and (3 forest biomass changes greater than 100 Mg·ha−1 or above 50% of 150 Mg·ha−1 are detectable using cross-normalized SAR data.

  14. Probing insect backscatter cross section and melanization using kHz optical remote detection system

    Science.gov (United States)

    Gebru, Alem; Brydegaard, Mikkel; Rohwer, Erich; Neethling, Pieter

    2017-01-01

    A kHz optical remote sensing system is implemented to determine insect melanization features. This is done by measuring the backscatter signal in the visible and near-infrared (VIS-NIR) and short-wave infrared (SWIR) in situ. It is shown that backscatter cross section in the SWIR is insensitive to melanization and absolute melanization can be derived from the ratio of backscatter cross section of different bands (SWIR/VIS-NIR). We have shown that reflectance from insect is stronger in the SWIR as compared to NIR and VIS. This reveals that melanization plays a big role to determine backscatter cross section. One can use this feature as a tool to improve insect species and age classification. To support the findings, we illustrated melanization feature using three different insects [dead, dried specimens of snow white moth (Spilosoma genus), fox moth (Macrothylacia), and leather beetle (Odontotaenius genus)]. It is shown that reflectance from the leather beetle in the VIS and NIR is more affected by melanization as compared with snow white moth.

  15. The energy loss of medium-energy He+ ions backscattered from a Cu(100) surface

    NARCIS (Netherlands)

    Alkemade, P.F.A.; Turkenburg, W.C.; Weg, W.F. van der

    A model is presented for the shape of the surface peak in the energy spectrum of backscattered ions in a channeling and blocking experiment. The elastic energy loss distribution of the ions is calculated by use of Monte Carlo simulation. The inelastic energy loss distribution is calculated by use of

  16. Relationships of S-Band Radar Backscatter and Forest Aboveground Biomass in Different Forest Types

    Directory of Open Access Journals (Sweden)

    Ramesh K. Ningthoujam

    2017-11-01

    Full Text Available Synthetic Aperture Radar (SAR signals respond to the interactions of microwaves with vegetation canopy scatterers that collectively characterise forest structure. The sensitivity of S-band (7.5–15 cm backscatter to the different forest types (broadleaved, needleleaved with varying aboveground biomass (AGB across temperate (mixed, needleleaved and tropical (broadleaved, woody savanna, secondary forests is less well understood. In this study, Michigan Microwave Canopy Scattering (MIMICS-I radiative transfer model simulations showed strong volume scattering returns from S-band SAR for broadleaved canopies caused by ground/trunk interactions. A general relationship between AirSAR S-band measurements and MIMICS-I simulated radar backscatter with forest AGB up to nearly 100 t/ha in broadleaved forest in the UK was found. Simulated S-band backscatter-biomass relationships suggest increasing backscatter sensitivity to forest biomass with a saturation level close to 100 t/ha and errors between 37 t/ha and 44 t/ha for HV and VV polarisations for tropical ecosystems. In the near future, satellite SAR-derived forest biomass from P-band BIOMASS mission and L-band ALOS-2 PALSAR-2 in combination with S-band UK NovaSAR-S and the joint NASA-ISRO NISAR sensors will provide better quantification of large-scale forest AGB at varying sensitivity levels across primary and secondary forests and woody savannas.

  17. A Laboratory Experiment on EM Backscatter from Farley-Buneman and Gradient Drift Waves

    DEFF Research Database (Denmark)

    Alport, M. J.; D'Angelo, N.; Pécseli, Hans

    1981-01-01

    Results are reported of a laboratory experiment on Bragg backscatter of 3-cm microwaves by turbulent waves driven by the Farley-Buneman and gradient drift instabilities. The present work is the third in a series of laboratory experiments performed to test, under controlled conditions, prevalent i...... ideas on EM scattering by equatorial and high-latitude ionospheric waves and irregularities....

  18. Investigation of the relationship between optical auroral forms and HF radar E region backscatter

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    2000-06-01

    Full Text Available The SuperDARN HF radars have been employed in the past to investigate the spectral characteristics of coherent backscatter from L-shell aligned features in the auroral E region. The present study employs all-sky camera observations of the aurora from Husafell, Iceland, and the two SuperDARN radars located on Iceland, Þykkvibær and Stokkseyri, to determine the optical signature of such backscatter features. It is shown that, especially during quiet geomagnetic conditions, the backscatter region is closely associated with east-west aligned diffuse auroral features, and that the two move in tandem with each other. This association between optical and radar aurora has repercussions for the instability mechanisms responsible for generating the E region irregularities from which radars scatter. This is discussed and compared with previous studies investigating the relationship between optical and VHF radar aurora. In addition, although it is known that E region backscatter is commonly observed by SuperDARN radars, the present study demonstrates for the first time that multiple radars can observe the same feature to extend over at least 3 h of magnetic local time, allowing precipitation features to be mapped over large portions of the auroral zone.Key words: Ionosphere (particle precipitation; plasma waves and instabilities

  19. Super-resolved time-frequency analysis of wideband backscattered data

    DEFF Research Database (Denmark)

    Moore, John; Ling, H.

    1995-01-01

    A time-frequency super-resolution procedure is presented for processing wideband backscattered data containing both scattering center and natural resonance information. In this procedure, Prony's method is first applied in the frequency domain to locate scattering centers. The data is processed one...

  20. Acoustic backscatter by suspended cohesive sediments: Field observations, Seine Estuary, France

    Science.gov (United States)

    Sahin, Cihan; Verney, Romaric; Sheremet, Alexandru; Voulgaris, George

    2017-02-01

    Observations of suspended sediment size and concentration, flow and acoustic backscatter intensity collected on the Seine Estuary (France) are used to study the acoustic response in cohesive-sediment dominated environments. Estimates of suspended sediment concentration based on optical backscatter sensors and water samples are used to calibrate the acoustic backscatter intensity. The vertical structure of suspended sediment concentration is then estimated from acoustic backscatter information. To our knowledge, this is the first field application of the recently proposed model of acoustic scattering by flocculating suspensions based on the variation of particle density (floc-scattering model). The estimates of sediment concentration reproduce well the observations under different tidal (neap/spring) conditions, confirming the applicability of the new model in the field when detailed particle size measurements are available. When particle size measurements are not available, using estimated floc sizes based on the turbulence intensities may provide reasonable SSC profiles. During spring tide events (associated with strong currents, small flocs and large concentrations), the performances of the new floc-scattering model and the previous models given for solid particle-scattering are comparable. The floc-scattering model increases the quality of the SSC estimates especially during low-energy conditions characterized with larger flocs.

  1. The effect of backscattering on the beta dose absorbed by individual quartz grains

    DEFF Research Database (Denmark)

    Autzen, Martin; Guérin, G.; Murray, A. S.

    2017-01-01

    We describe the effect on dose rates and over-dispersion (OD) of changing the spectrum of energies to which grains of various shapes and volumes are exposed during beta irradiation, either by changing the backscattering medium or attenuating the incident spectrum. Dose rates are found to increase...

  2. Multi-angle backscatter classification and sub-bottom profiling for improved seafloor characterization

    Science.gov (United States)

    Alevizos, Evangelos; Snellen, Mirjam; Simons, Dick; Siemes, Kerstin; Greinert, Jens

    2017-06-01

    This study applies three classification methods exploiting the angular dependence of acoustic seafloor backscatter along with high resolution sub-bottom profiling for seafloor sediment characterization in the Eckernförde Bay, Baltic Sea Germany. This area is well suited for acoustic backscatter studies due to its shallowness, its smooth bathymetry and the presence of a wide range of sediment types. Backscatter data were acquired using a Seabeam1180 (180 kHz) multibeam echosounder and sub-bottom profiler data were recorded using a SES-2000 parametric sonar transmitting 6 and 12 kHz. The high density of seafloor soundings allowed extracting backscatter layers for five beam angles over a large part of the surveyed area. A Bayesian probability method was employed for sediment classification based on the backscatter variability at a single incidence angle, whereas Maximum Likelihood Classification (MLC) and Principal Components Analysis (PCA) were applied to the multi-angle layers. The Bayesian approach was used for identifying the optimum number of acoustic classes because cluster validation is carried out prior to class assignment and class outputs are ordinal categorical values. The method is based on the principle that backscatter values from a single incidence angle express a normal distribution for a particular sediment type. The resulting Bayesian classes were well correlated to median grain sizes and the percentage of coarse material. The MLC method uses angular response information from five layers of training areas extracted from the Bayesian classification map. The subsequent PCA analysis is based on the transformation of these five layers into two principal components that comprise most of the data variability. These principal components were clustered in five classes after running an external cluster validation test. In general both methods MLC and PCA, separated the various sediment types effectively, showing good agreement (kappa >0.7) with the Bayesian

  3. Characteristics of CALIOP attenuated backscatter noise: implication for cloud/aerosol detection

    Directory of Open Access Journals (Sweden)

    D. L. Wu

    2011-03-01

    Full Text Available A research algorithm is developed for noise evaluation and feature detection of the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization Level 1 (L1 backscatter data with an emphasis on cloud/aerosol features in the upper troposphere and lower stratosphere (UT/LS. CALIOP measurement noise of the version v2.01 and v2.02 L1 backscatter data aggregated to (5 km horizontal resolution is analyzed with two approaches in this study. One is to compare the observed and modeled molecular scatter profiles by scaling the modeled profile (with a fitted scaling factor α to the observed clear-sky backscatter profiles. This scaling α value is sensitive to errors in the calibrated backscatter and the atmospheric model used. Most of the nighttime 532-nm α values are close to unity, as expected, but an abrupt drop occurred in October 2008 in the daytime 532-nm α, which is likely indicative of a problem in the v2.02 daytime calibrated data. The 1064-nm night α is generally close to 2 while its day α is ~3. The other approach to evaluate the lidar measurement noise is to use the calibrated lidar backscatter data at altitudes above 19 km. With this method, the 532-nm and 1064-nm measurement noises are analyzed and characterized individually for each profile in terms of the mean (μ and standard deviation (σ, showing larger σ values in general over landmasses or bright surfaces during day and in radiation-hard regions during night. A significant increasing trend is evident in the nighttime 1064-nm σ, which is likely responsible for the increasing difference between the feature occurrence frequencies (532-nm vs. 1064-nm derived from this study. For feature detection with the research algorithm, we apply a σ–based method to the aggregated L1 data. The derived morphology of feature occurrence frequency is in general agreement with that obtained from the Level 2 (L2 05 km_CLAY+05 km_ALAY products at 5 km horizontal resolution. Finally, a normalized

  4. Monte Carlo simulation of MOSFET dosimeter for electron backscatter using the GEANT4 code.

    Science.gov (United States)

    Chow, James C L; Leung, Michael K K

    2008-06-01

    The aim of this study is to investigate the influence of the body of the metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter in measuring the electron backscatter from lead. The electron backscatter factor (EBF), which is defined as the ratio of dose at the tissue-lead interface to the dose at the same point without the presence of backscatter, was calculated by the Monte Carlo simulation using the GEANT4 code. Electron beams with energies of 4, 6, 9, and 12 MeV were used in the simulation. It was found that in the presence of the MOSFET body, the EBFs were underestimated by about 2%-0.9% for electron beam energies of 4-12 MeV, respectively. The trend of the decrease of EBF with an increase of electron energy can be explained by the small MOSFET dosimeter, mainly made of epoxy and silicon, not only attenuated the electron fluence of the electron beam from upstream, but also the electron backscatter generated by the lead underneath the dosimeter. However, this variation of the EBF underestimation is within the same order of the statistical uncertainties as the Monte Carlo simulations, which ranged from 1.3% to 0.8% for the electron energies of 4-12 MeV, due to the small dosimetric volume. Such small EBF deviation is therefore insignificant when the uncertainty of the Monte Carlo simulation is taken into account. Corresponding measurements were carried out and uncertainties compared to Monte Carlo results were within +/- 2%. Spectra of energy deposited by the backscattered electrons in dosimetric volumes with and without the lead and MOSFET were determined by Monte Carlo simulations. It was found that in both cases, when the MOSFET body is either present or absent in the simulation, deviations of electron energy spectra with and without the lead decrease with an increase of the electron beam energy. Moreover, the softer spectrum of the backscattered electron when lead is present can result in a reduction of the MOSFET response due to stronger

  5. 3D leaf water content mapping using terrestrial laser scanner backscatter intensity with radiometric correction

    Science.gov (United States)

    Zhu, Xi; Wang, Tiejun; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Niemann, K. Olaf

    2015-12-01

    Leaf water content (LWC) plays an important role in agriculture and forestry management. It can be used to assess drought conditions and wildfire susceptibility. Terrestrial laser scanner (TLS) data have been widely used in forested environments for retrieving geometrically-based biophysical parameters. Recent studies have also shown the potential of using radiometric information (backscatter intensity) for estimating LWC. However, the usefulness of backscatter intensity data has been limited by leaf surface characteristics, and incidence angle effects. To explore the idea of using LiDAR intensity data to assess LWC we normalized (for both angular effects and leaf surface properties) shortwave infrared TLS data (1550 nm). A reflectance model describing both diffuse and specular reflectance was applied to remove strong specular backscatter intensity at a perpendicular angle. Leaves with different surface properties were collected from eight broadleaf plant species for modeling the relationship between LWC and backscatter intensity. Reference reflectors (Spectralon from Labsphere, Inc.) were used to build a look-up table to compensate for incidence angle effects. Results showed that before removing the specular influences, there was no significant correlation (R2 = 0.01, P > 0.05) between the backscatter intensity at a perpendicular angle and LWC. After the removal of the specular influences, a significant correlation emerged (R2 = 0.74, P < 0.05). The agreement between measured and TLS-derived LWC demonstrated a significant reduction of RMSE (root mean square error, from 0.008 to 0.003 g/cm2) after correcting for the incidence angle effect. We show that it is possible to use TLS to estimate LWC for selected broadleaved plants with an R2 of 0.76 (significance level α = 0.05) at leaf level. Further investigations of leaf surface and internal structure will likely result in improvements of 3D LWC mapping for studying physiology and ecology in vegetation.

  6. Multi-Polarization ASAR Backscattering from Herbaceous Wetlands in Poyang Lake Region, China

    Directory of Open Access Journals (Sweden)

    Huiyong Sang

    2014-05-01

    Full Text Available Wetlands are one of the most important ecosystems on Earth. There is an urgent need to quantify the biophysical parameters (e.g., plant height, aboveground biomass and map total remaining areas of wetlands in order to evaluate the ecological status of wetlands. In this study, Environmental Satellite/Advanced Synthetic Aperture Radar (ENVISAT/ASAR dual-polarization C-band data acquired in 2005 is tested to investigate radar backscattering mechanisms with the variation of hydrological conditions during the growing cycle of two types of herbaceous wetland species, which colonize lake borders with different elevation in Poyang Lake region, China. Phragmites communis (L. Trin. is semi-aquatic emergent vegetation with vertical stem and blade-like leaves, and the emergent Carex spp. has rhizome and long leaves. In this study, the potential of ASAR data in HH-, HV-, and VV-polarization in mapping different wetland types is examined, by observing their dynamic variations throughout the whole flooding cycle. The sensitivity of ASAR backscattering coefficients to vegetation parameters of plant height, fresh and dry biomass, and vegetation water content is also analyzed for Phragmites communis (L. Trin. and Carex spp. The research for Phragmites communis (L. Trin. shows that HH polarization is more sensitive to plant height and dry biomass than HV polarization. ASAR backscattering coefficients are relatively less sensitive to fresh biomass, especially in HV polarization. However, both are highly dependent on canopy water content. In contrast, the dependence of HH- and HV- backscattering from Carex community on vegetation parameters is poor, and the radar backscattering mechanism is controlled by ground water level.

  7. Lead-nickel electrochemical batteries

    CERN Document Server

    Glaize, Christian

    2012-01-01

    The lead-acid accumulator was introduced in the middle of the 19th Century, the diverse variants of nickel accumulators between the beginning and the end of the 20th Century. Although old, these technologies are always very present on numerous markets. Unfortunately they are still not used in optimal conditions, often because of the misunderstanding of the internal electrochemical phenomena.This book will show that batteries are complex systems, made commercially available thanks to considerable amounts of scientific research, empiricism and practical knowledge. However, the design of

  8. Printed-Compliant Electrochemical Systems

    Science.gov (United States)

    Gaikwad, Abhinav Machhindra

    Compliant electronic devices such as health monitoring tags, wearable electronics, fabricated using add-on printing techniques or by patterning traditional silicon based electronics in ultrathin format, enable them to flex, stretch and twist without any noticeable change in performance. These devices require a power source---a primary or secondary battery---to power the electronics. Traditional forms of batteries are bulky and negate the advantages of this new class of devices. Herein, I investigate various printing techniques and architectures that enable compliant batteries and study the performance of such batteries under mechanical deformations. Firstly, this dissertation investigates electrochemical-mechanical performance of a dispenser printed micro-battery using a microfluidic cell. Nanoparticulate silver ink was printed and cured to form silver electrodes, which was charged in-situ to form a silver-zinc battery. The electrochemical performance of the silver-zinc micro-battery was similar to macro-sized batteries. The shear stress generated by flow of electrolyte over the electrode was used to emulate the shear stress generated during flexing and was used as a tool to study the shear strength of the silver electrode at different state of charge. The dissertation then investigates supported architecture as a reinforcement to maintain the performance of the battery under strain. We demonstrate a highly flexible Zn-MnO2 alkalinebattery by embedding the electrochemically active particles in a mesh support. The mesh support absorbs the stresses generated during flexing. A Similar principle was used to make a stretchable battery. The backbone of the stretchable electrode was a stretchable fabric with silver-coated fibers weaved through a rubber network, which served as the current collector. The fabric was coated with Zn and MnO2 to form a stretchable electrode. Due to the weave architecture the electrode could stretch by 100% without any loss is contact between

  9. All-Polymer Electrochemical Sensors

    DEFF Research Database (Denmark)

    Kafka, Jan Robert

    This thesis presents fabrication strategies to produce different types of all-polymer electrochemical sensors based on electrodes made of the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Three different systems are presented, fabricated either by using microdrilling or by hot...... arrays towards potassium ferrocyanide. A sensor application was demonstrated by amperometric detection of hydrogen peroxide concentrations in the range of 0.1 to5 mM. Planar electrodes were fabricated by hot embossing of a microfluidic channel with sloped sidewalls into a PEDOT covered COC bulk material...

  10. Electrochemically switchable polypyrrole coated membranes

    Energy Technology Data Exchange (ETDEWEB)

    Weidlich, Claudia, E-mail: weidlich@dechema.d [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany); Mangold, Klaus-Michael [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany)

    2011-04-01

    A method for coating membranes with polypyrrole (PPy) has been developed. Different membranes, such as microfiltration as well as ion exchanger membranes have been coated with PPy to yield electrical conductivity of the membranes. The coated membranes have been investigated by cyclic voltammetry and scanning electron microscopy and their permeability and permselectivity have been tested. The results show that PPy can be tailored as cation or anion exchanger and its porosity can be controlled to avoid any impairment of the membrane by the polymer layer. These PPy coated membranes can be applied as electrochemically switchable, functionalised membranes with controllabel and variable separation properties.

  11. Three dimensional electrochemical system for neurobiological studies

    DEFF Research Database (Denmark)

    Vazquez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

    2009-01-01

    In this work we report a novel three dimensional electrode array for electrochemical measurements in neuronal studies. The main advantage of working with these out-of-plane structures is the enhanced sensitivity of the system in terms of measuring electrochemical changes in the environment of a c...

  12. Electrochemical Promotion of Catalytic Reactions Using

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cleemann, Lars Nilausen

    2007-01-01

    This paper presents the results of a study on electrochemical promotion (EP) of catalytic reactions using Pt/C/polybenzimidazole(H3PO4)/Pt/C fuel cell performed by the Energy and Materials Science Group (Technical University of Denmark) during the last 6 years[1-4]. The development of our...... understanding of the nature of the electrochemical promotion is also presented....

  13. Non-aqueous electrolytes for electrochemical cells

    Science.gov (United States)

    Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

    2016-06-14

    An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

  14. Graphene-Paper Based Electrochemical Sensors

    DEFF Research Database (Denmark)

    Zhang, Minwei; Halder, Arnab; Cao, Xianyi

    2017-01-01

    in electrochemical sensors and energy technologies amongothers. In this chapter, we present some examples to overview recent advances in theresearch and development of two-dimensional (2D) graphene papers as new materialsfor electrochemical sensors. The chapter covers the design, fabrication, functionalizationand...

  15. Electrochemical and Spectroscopic Studies of Molten Halides

    Science.gov (United States)

    1993-01-08

    C. Decroly , A. Mukhtar, and R. Winand, J. Electrochem. Soc., 115, 905 (1968). 10. D. Inman and S. H. White, J. Appl. Electrochen., 8, 375 (1978). 11...R.L.: Ibid., 1966, 44, 1166. 9) Decroly , C., Mukhtar, A. and Winand, R.: J. Electrochem. Soc., 1968, 115, 905. 10) Inman, D. and White, S.A!.: J. Appl

  16. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  17. Space Electrochemical Research and Technology

    Science.gov (United States)

    Wilson, Richard M. (Compiler)

    1996-01-01

    Individual papers presented at the conference address the following topics: development of a micro-fiber nickel electrode for nickel-hydrogen cell, high performance nickel electrodes for space power application, bending properties of nickel electrodes for nickel-hydrogen batteries, effect of KOH concentration and anions on the performance of a Ni-H2 battery positive plate, advanced dependent pressure vessel nickel hydrogen spacecraft cell and battery design, electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery design, a novel unitized regenerative proton exchange membrane fuel cell, fuel cell systems for first lunar outpost - reactant storage options, the TMI regenerable solid oxide fuel cell, engineering development program of a closed aluminum-oxygen semi-cell system for an unmanned underwater vehicle, SPE OBOGS on-board oxygen generating system, hermetically sealed aluminum electrolytic capacitor, sol-gel technology and advanced electrochemical energy storage materials, development of electrochemical supercapacitors for EMA applications, and high energy density electrolytic capacitor.

  18. Electrochemical treatment of liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Savannah River Technology Center, Aiken, SC (United States)

    1997-10-01

    Under this task, electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This technology targets the (1) destruction of nitrates, nitrites and organic compounds; (2) removal of radionuclides; and (3) removal of RCRA metals. The development program consists of five major tasks: (1) evaluation of electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale reactor, and (5) analysis and evaluation of test data. The development program team is comprised of individuals from national laboratories, academic institutions, and private industry. Possible benefits of this technology include: (1) improved radionuclide separation as a result of the removal of organic complexants, (2) reduction in the concentrations of hazardous and radioactive species in the waste (e.g., removal of nitrate, mercury, chromium, cadmium, {sup 99}Tc, and {sup 106}Ru), (3) reduction in the size of the off-gas handling equipment for the vitrification of low-level waste (LLW) by reducing the source of NO{sub x} emissions, (4) recovery of chemicals of value (e.g. sodium hydroxide), and (5) reduction in the volume of waste requiring disposal.

  19. Bussing Structure In An Electrochemical Cell

    Science.gov (United States)

    Romero, Antonio L.

    2001-06-12

    A bussing structure for bussing current within an electrochemical cell. The bussing structure includes a first plate and a second plate, each having a central aperture therein. Current collection tabs, extending from an electrode stack in the electrochemical cell, extend through the central aperture in the first plate, and are then sandwiched between the first plate and second plate. The second plate is then connected to a terminal on the outside of the case of the electrochemical cell. Each of the first and second plates includes a second aperture which is positioned beneath a safety vent in the case of the electrochemical cell to promote turbulent flow of gasses through the vent upon its opening. The second plate also includes protrusions for spacing the bussing structure from the case, as well as plateaus for connecting the bussing structure to the terminal on the case of the electrochemical cell.

  20. Novel X-ray backscatter technique for detection of dangerous materials: application to aviation and port security

    Science.gov (United States)

    Kolkoori, S.; Wrobel, N.; Osterloh, K.; Zscherpel, U.; Ewert, U.

    2013-09-01

    Radiological inspections, in general, are the nondestructive testing (NDT) methods to detect the bulk of explosives in large objects. In contrast to personal luggage, cargo or building components constitute a complexity that may significantly hinder the detection of a threat by conventional X-ray transmission radiography. In this article, a novel X-ray backscatter technique is presented for detecting suspicious objects in a densely packed large object with only a single sided access. It consists of an X-ray backscatter camera with a special twisted slit collimator for imaging backscattering objects. The new X-ray backscatter camera is not only imaging the objects based on their densities but also by including the influences of surrounding objects. This unique feature of the X-ray backscatter camera provides new insights in identifying the internal features of the inspected object. Experimental mock-ups were designed imitating containers with threats among a complex packing as they may be encountered in reality. We investigated the dependence of the quality of the X-ray backscatter image on (a) the exposure time, (b) multiple exposures, (c) the distance between object and slit camera, and (d) the width of the slit. At the end, the significant advantages of the presented X-ray backscatter camera in the context of aviation and port security are discussed.

  1. Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function

    Science.gov (United States)

    Vijayan, Sarath; Xiong, Zhenyu; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

    2017-03-01

    Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the xray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the nonuniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.

  2. Investigating the backscattering characteristics of individual normal and cancerous cells based on experimentally determined three-dimensional refractive index distributions

    Science.gov (United States)

    Hsu, Wei-Chen; Su, Jing-Wei; Chang, Chih-Chiang; Sung, Kung-Bin

    2012-12-01

    The progression of epithelial dysplasia is accompanied by changes of sub-cellular structures which alter light scattering, particularly backscattering, properties of epithelial cells. In this study, we quantified the refractive index (RI) distributions of normal and cancerous epithelial cells of skin and oral cavity using digital holographic microtomography and investigated the backscattering characteristics of the cells using finite-difference time-domain simulations. The results show that cancerous cells present higher average values of nuclear and nucleolar RI and a higher standard deviation of cytoplasmic RI than normal cells. Both the total scattering and backscattering cross-sections of the cancerous cells are significantly higher than those of the normal cells.

  3. Phase Identification of Dual-Phase (DP980) Steels by Electron Backscatter Diffraction and Nanoindentation Techniques.

    Science.gov (United States)

    Zhang, Fan; Ruimi, Annie; Field, David P

    2016-02-01

    Phase identification of multi-phase materials provides essential information relating the material to its mechanical properties. In this study we selected DP980, a type of dual-phase steel, to investigate the content of martensite and ferrite grains. A combination of advanced techniques was used to provide detailed and precise information of the microstructure. Scanning and transmission electron microscopy were used to provide observations of the sample surface at different scales. Martensite and ferrite phases of DP980 were further identified and characterized using electron backscatter diffraction and scanning probe microscopy. Results obtained with nanoindentation tests confirmed that the differences in nanohardness values in single-phase grains are martensite and ferrite with different surface heights shown by scanning probe microscopy. The similarity shown in the image quality map and scanning probe microscopy proves that a large fraction of martensite can be distinguished in this undeformed material using image quality parameters obtained during electron backscatter diffraction imaging.

  4. Radiological Shielding Design for the Neutron High-Resolution Backscattering Spectrometer EMU at the OPAL Reactor

    Science.gov (United States)

    Ersez, Tunay; Esposto, Fernando; Souza, Nicolas R. de

    2017-09-01

    The shielding for the neutron high-resolution backscattering spectrometer (EMU) located at the OPAL reactor (ANSTO) was designed using the Monte Carlo code MCNP 5-1.60. The proposed shielding design has produced compact shielding assemblies, such as the neutron pre-monochromator bunker with sliding cylindrical block shields to accommodate a range of neutron take-off angles, and in the experimental area - shielding of neutron focusing guides, choppers, flight tube, backscattering monochromator, and additional shielding elements inside the Scattering Tank. These shielding assemblies meet safety and engineering requirements and cost constraints. The neutron dose rates around the EMU instrument were reduced to < 0.5 µSv/h and the gamma dose rates to a safe working level of ≤ 3 µSv/h.

  5. Coherent backscattering and forward-scattering peaks in the quantum kicked rotor

    Science.gov (United States)

    Lemarié, G.; Müller, Cord A.; Guéry-Odelin, D.; Miniatura, C.

    2017-04-01

    We propose and analyze an experimental scheme using the quantum kicked rotor to observe the newly predicted coherent forward-scattering peak together with its long-known twin brother, the coherent backscattering peak. Contrary to coherent backscattering, which arises already under weak-localization conditions, coherent forward scattering is only triggered by Anderson or strong localization. So far, coherent forward scattering has not been observed in conservative systems with elastic scattering by spatial disorder. We propose to turn to the quantum kicked rotor, which has a long and successful history as an accurate experimental platform to observe dynamical localization, i.e., Anderson localization in momentum space. We analyze the coherent forward-scattering effect for the quantum kicked rotor by extensive numerical simulations, both in the orthogonal and unitary class of disordered quantum systems, and show that an experimental realization involving phase-space rotation techniques is within reach of state-of-the-art cold-atom experiments.

  6. Method and apparatus for shadow aperture backscatter radiography (SABR) system and protocol

    Science.gov (United States)

    Shedlock, Daniel (Inventor); Jacobs, Alan M. (Inventor); Jacobs, Sharon Auerback (Inventor); Dugan, Edward (Inventor)

    2010-01-01

    A shadow aperture backscatter radiography (SABR) system includes at least one penetrating radiation source for providing a penetrating radiation field, and at least one partially transmissive radiation detector, wherein the partially transmissive radiation detector is interposed between an object region to be interrogated and the radiation source. The partially transmissive radiation detector transmits a portion of the illumination radiation field. A shadow aperture having a plurality of radiation attenuating regions having apertures therebetween is disposed between the radiation source and the detector. The apertures provide illumination regions for the illumination radiation field to reach the object region, wherein backscattered radiation from the object is detected and generates an image by the detector in regions of the detector that are shadowed by the radiation attenuation regions.

  7. Bulk elastic waves with unidirectional backscattering-immune topological states in a time-dependent superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Swinteck, N., E-mail: swinteck@email.arizona.edu; Matsuo, S.; Runge, K.; Lucas, P.; Deymier, P. A. [Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721 (United States); Vasseur, J. O. [Institut d' Electronique, de Micro-électronique et de Nanotechnologie, UMR CNRS 8520, Cité Scientifique, 59652 Villeneuve d' Ascq Cedex (France)

    2015-08-14

    Recent progress in electronic and electromagnetic topological insulators has led to the demonstration of one way propagation of electron and photon edge states and the possibility of immunity to backscattering by edge defects. Unfortunately, such topologically protected propagation of waves in the bulk of a material has not been observed. We show, in the case of sound/elastic waves, that bulk waves with unidirectional backscattering-immune topological states can be observed in a time-dependent elastic superlattice. The superlattice is realized via spatial and temporal modulation of the stiffness of an elastic material. Bulk elastic waves in this superlattice are supported by a manifold in momentum space with the topology of a single twist Möbius strip. Our results demonstrate the possibility of attaining one way transport and immunity to scattering of bulk elastic waves.

  8. Comparison of aerosol lidar retrieval methods for boundary layer height detection using ceilometer aerosol backscatter data

    Science.gov (United States)

    Caicedo, Vanessa; Rappenglück, Bernhard; Lefer, Barry; Morris, Gary; Toledo, Daniel; Delgado, Ruben

    2017-04-01

    Three algorithms for estimating the boundary layer heights are assessed: an aerosol gradient method, a cluster analysis method, and a Haar wavelet method. Over 40 daytime clear-sky radiosonde profiles are used to compare aerosol backscatter boundary layer heights retrieved by a Vaisala CL31 ceilometer. Overall good agreement between radiosonde- and aerosol-derived boundary layer heights was found for all methods. The cluster method was found to be particularly sensitive to noise in ceilometer signals and lofted aerosol layers (48.8 % of comparisons), while the gradient method showed limitations in low-aerosol-backscatter conditions. The Haar wavelet method was demonstrated to be the most robust, only showing limitations in 22.5 % of all observations. Occasional differences between thermodynamically and aerosol-derived boundary layer heights were observed.

  9. Backscatter Transponder Based on Frequency Selective Surface for FMCW Radar Applications

    Directory of Open Access Journals (Sweden)

    A.Lazaro

    2014-06-01

    Full Text Available This paper describes an actively-controlled frequency selective surface (FSS to implement a backscatter transponder. The FSS is composed by dipoles loaded with switching PIN diodes. The transponder exploits the change in the radar cross section (RCS of the FSS with the bias of the diodes to modulate the backscattered response of the tag to the FMCW radar. The basic operation theory of the system is explained here. An experimental setup based on a commercial X-band FMCW radar working as a reader is proposed to measure the transponders. The transponder response can be distinguished from the interference of non-modulated clutter, modulating the transponder’s RCS. Some FSS with different number of dipoles are studied, as a proof of concept. Experimental results at several distances are provided.

  10. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.

    Key words. Ionosphere (ionospheric irregularities

  11. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    2001-02-01

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.Key words. Ionosphere (ionospheric irregularities

  12. Simultaneous detection of rotational and translational motion in optical tweezers by measurement of backscattered intensity

    CERN Document Server

    Roy, Basudev; Banerjee, Ayan

    2014-01-01

    We describe a simple yet powerful technique of simultaneously measuring both translational and rotational motion of mesoscopic particles in optical tweezers by measuring the backscattered intensity on a quadrant photodiode (QPD). While the measurement of translational motion by taking the difference of the backscattered intensity incident on adjacent quadrants of a QPD is well-known, we demonstrate that rotational motion can be measured very precisely by taking the difference between the diagonal quadrants. The latter measurement eliminates the translational component entirely, and leads to a detection sensitivity of around 50 mdeg at S/N of 2 for angular motion of a driven micro-rod. The technique is also able to resolve the translational and rotational Brownian motion components of the micro-rod in an unperturbed trap, and can be very useful in measuring translation-rotation coupling of micro-objects induced by hydrodynamic interactions.

  13. A three-part geometric model to predict the radar backscatter from wheat, corn, and sorghum

    Science.gov (United States)

    Ulaby, F. T. (Principal Investigator); Eger, G. W., III; Kanemasu, E. T.

    1982-01-01

    A model to predict the radar backscattering coefficient from crops must include the geometry of the canopy. Radar and ground-truth data taken on wheat in 1979 indicate that the model must include contributions from the leaves, from the wheat head, and from the soil moisture. For sorghum and corn, radar and ground-truth data obtained in 1979 and 1980 support the necessity of a soil moisture term and a leaf water term. The Leaf Area Index (LAI) is an appropriate input for the leaf contribution to the radar response for wheat and sorghum, however the LAI generates less accurate values for the backscattering coefficient for corn. Also, the data for corn and sorghum illustrate the importance of the water contained in the stalks in estimating the radar response.

  14. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

    2014-04-01

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

  15. Composite Electrodes for Electrochemical Supercapacitors

    Directory of Open Access Journals (Sweden)

    Yang QuanMin

    2010-01-01

    Full Text Available Abstract Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7–15 mg cm−2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC. The highest SC of 185 F g−1 was obtained at a scan rate of 2 mV s−1 for mass loading of 7 mg cm−2. The SC decreased with increasing scan rate and increasing electrode mass.

  16. Scanning Electrochemical Microscopy in Neuroscience

    Science.gov (United States)

    Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

    2010-07-01

    This article reviews recent work involving the application of scanning electrochemical microscopy (SECM) to the study of individual cultured living cells, with an emphasis on topographical and functional imaging of neuronal and secretory cells of the nervous and endocrine system. The basic principles of biological SECM and associated negative amperometric-feedback and generator/collector-mode SECM imaging are discussed, and successful use of the methodology for screening soft and fragile membranous objects is outlined. The drawbacks of the constant-height mode of probe movement and the benefits of the constant-distance mode of SECM operation are described. Finally, representative examples of constant-height and constant-distance mode SECM on a variety of live cells are highlighted to demonstrate the current status of single-cell SECM in general and of SECM in neuroscience in particular.

  17. Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    1998-01-01

    Full Text Available A common feature of evening near-range ionospheric backscatter in the CUTLASS Iceland radar field of view is two parallel, approximately L-shell-aligned regions of westward flow which are attributed to irregularities in the auroral eastward electrojet region of the ionosphere. These backscatter channels are separated by approximately 100–200 km in range. The orientation of the CUTLASS Iceland radar beams and the zonally aligned nature of the flow allows an approximate determination of flow angle to be made without the necessity of bistatic measurements. The two flow channels have different azimuthal variations in flow velocity and spectral width. The nearer of the two regions has two distinct spectral signatures. The eastern beams detect spectra with velocities which saturate at or near the ion-acoustic speed, and have low spectral widths (less than 100 m s–1, while the western beams detect lower velocities and higher spectral widths (above 200 m s–1. The more distant of the two channels has only one spectral signature with velocities above the ion-acoustic speed and high spectral widths. The spectral characteristics of the backscatter are consistent with E-region scatter in the nearer channel and upper-E-region or F-region scatter in the further channel. Temporal variations in the characteristics of both channels support current theories of E-region turbulent heating and previous observations of velocity-dependent backscatter cross-section. In future, observations of this nature will provide a powerful tool for the investigation of simultaneous E- and F-region irregularity generation under similar (nearly co-located or magnetically conjugate electric field conditions.Key words. Auroral ionosphere · Ionospheric irregularities · Plasma convection

  18. Pathfinder: applying graph theory to consistent tracking of daytime mixed layer height with backscatter lidar

    Science.gov (United States)

    de Bruine, Marco; Apituley, Arnoud; Donovan, David Patrick; Klein Baltink, Hendrik; Jorrit de Haij, Marijn

    2017-05-01

    The height of the atmospheric boundary layer or mixing layer is an important parameter for understanding the dynamics of the atmosphere and the dispersion of trace gases and air pollution. The height of the mixing layer (MLH) can be retrieved, among other methods, from lidar or ceilometer backscatter data. These instruments use the vertical backscatter lidar signal to infer MLHL, which is feasible because the main sources of aerosols are situated at the surface and vertical gradients are expected to go from the aerosol loaded mixing layer close to the ground to the cleaner free atmosphere above. Various lidar/ceilometer algorithms are currently applied, but accounting for MLH temporal development is not always well taken care of. As a result, MLHL retrievals may jump between different atmospheric layers, rather than reliably track true MLH development over time. This hampers the usefulness of MLHL time series, e.g. for process studies, model validation/verification and climatology. Here, we introduce a new method pathfinder, which applies graph theory to simultaneously evaluate time frames that are consistent with scales of MLH dynamics, leading to coherent tracking of MLH. Starting from a grid of gradients in the backscatter profiles, MLH development is followed using Dijkstra's shortest path algorithm (Dijkstra, 1959). Locations of strong gradients are connected under the condition that subsequent points on the path are limited to a restricted vertical range. The search is further guided by rules based on the presence of clouds and residual layers. After being applied to backscatter lidar data from Cabauw, excellent agreement is found with wind profiler retrievals for a 12-day period in 2008 (R2 = 0.90) and visual judgment of lidar data during a full year in 2010 (R2 = 0.96). These values compare favourably to other MLHL methods applied to the same lidar data set and corroborate more consistent MLH tracking by pathfinder.

  19. Mapping Wetlands in Zambia Using Seasonal Backscatter Signatures Derived from ENVISAT ASAR Time Series

    OpenAIRE

    Stefan Schlaffer; Marco Chini; Denise Dettmering; Wolfgang Wagner

    2016-01-01

    Wetlands are considered a challenging environment for mapping approaches based on Synthetic Aperture Radar (SAR) data due to their often complex internal structures and the diverse backscattering mechanisms caused by vegetation, soil moisture and flood dynamics contributing to the resulting imagery. In this study, a time series of >100 SAR images acquired by ENVISAT during a time period of ca. two years over the Kafue River basin in Zambia was compared to water heights derived from radar a...

  20. Backscattering of Ground Terrain and Building Materials at Millimeter-Wave and Terahertz Frequencies

    Science.gov (United States)

    2013-06-01

    for the 0.1 – 0.3 THz region continues to grow. Much work has been done on studying the dielectric and scattering properties of various types of...A preliminary investigation was made of the 100 GHz and 240 GHz radar backscattering coefficient of sand, gravel, topsoil with various moisture...of generic topsoil that consisted of course organic soil as well as some small twigs and stones. The soil was first baked in a vacuum oven at 120

  1. Simulation of radar backscattering from snowpack at X-band and Ku-band

    Science.gov (United States)

    Gay, Michel; Phan, Xuan-Vu; Ferro-Famil, Laurent

    2016-04-01

    This paper presents a multilayer snowpack electromagnetic backscattering model, based on Dense Media Radiative Transfer (DMRT). This model is capable of simulating the interaction of electromagnetic wave (EMW) at X-band and Ku-band frequencies with multilayer snowpack. The air-snow interface and snow-ground backscattering components are calculated using the Integral Equation Model (IEM) by [1], whereas the volume backscattering component is calculated based on the solution of Vector Radiative Transfer (VRT) equation at order 1. Case study has been carried out using measurement data from NoSREx project [2], which include SnowScat data in X-band and Ku-band, TerraSAR-X acquisitions and snowpack stratigraphic in-situ measurements. The results of model simulations show good agreement with the radar observations, and therefore allow the DMRT model to be used in various applications, such as data assimilation [3]. [1] A.K. Fung and K.S. Chen, "An update on the iem surface backscattering model," Geoscience and Remote Sensing Letters, IEEE, vol. 1, no. 2, pp. 75 - 77, april 2004. [2] J. Lemmetyinen, A. Kontu, J. Pulliainen, A. Wiesmann, C. Werner, T. Nagler, H. Rott, and M. Heidinger, "Technical assistance for the deployment of an x- to ku-band scatterometer during the nosrex ii experiment," Final Report, ESA ESTEC Contract No. 22671/09/NL/JA., 2011. [3] X. V. Phan, L. Ferro-Famil, M. Gay, Y. Durand, M. Dumont, S. Morin, S. Allain, G. D'Urso, and A. Girard, "3d-var multilayer assimilation of x-band sar data into a detailed snowpack model," The Cryosphere Discussions, vol. 7, no. 5, pp. 4881-4912, 2013.

  2. Broadband measurements of the acoustic backscatter cross section of sand particles in suspension

    Energy Technology Data Exchange (ETDEWEB)

    He, C.; Hay, A.E. (Memorial Univ. of Newfoundland, St. John' s, Newfoundland (Canada))

    1993-10-01

    A method using a broadband transducer to measure the acoustic backscatter cross section of suspended sand particles is investigated. The frequencies used range from 1.3 to 2.8 MHz, and the sand sizes from 100- to 350-[mu]m diameter. The measurements are made in the transducer near field. The measured form factor is compared with the theoretical result for the movable rigid sphere model, and with previous narrow-band measurements. 29 refs., 8 figs., 3 tabs.

  3. Effect of articular cartilage proteoglycan depletion on high frequency ultrasound backscatter.

    Science.gov (United States)

    Pellaumail, B; Watrin, A; Loeuille, D; Netter, P; Berger, G; Laugier, P; Saïed, A

    2002-07-01

    To study the effect of variations of articular cartilage proteoglycans (PG) on high-frequency ultrasound backscatter. The study was performed on patellar cartilages of immature and mature rats (N=36). The variation of PG content was induced by enzyme digestion. Control and treated cartilages were explored in vitro using a 55MHz scanning acoustic microscopy, then assessed by histology for the fibrillar collagen organization analysis. The variations of proteoglycan and collagen content were evaluated. Thickness measurements performed on both B-scan images and histologic sections were compared. Ultrasonic radio-frequency signals reflected by the cartilage surface and backscattered from its internal matrix were processed to estimate the integrated reflection coefficient (IRC) and apparent integrated backscatter (AIB). Although hyaluronidase treatment of immature and mature cartilages removed approximately 50% of the proteoglycans, the echogenicity level of ultrasound images of degraded cartilages was similar to that of controls. IRC and AIB parameters did not significantly vary. Histologic sections of degraded cartilage displayed no change in collagen fiber organization. The thickness mean values measured by ultrasound in PG-depleted groups were significantly higher than in controls, whereas no significant difference in thickness was detected by histological measurement. The increase in cartilage thickness may potentially be explained by a decrease of speed of sound in PG-depleted cartilages that is more likely subsequent to an increase of water content. Current results indicate that PG depletion has no significant effect on high frequency ultrasound backscattered from rat patellar cartilage. Ultrasound may provide information about variations of PG content via speed of sound measurement. Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

  4. Infrared reflectometry of skin: Analysis of backscattered light from different skin layers

    Science.gov (United States)

    Pleitez, Miguel A.; Hertzberg, Otto; Bauer, Alexander; Lieblein, Tobias; Glasmacher, Mathias; Tholl, Hans; Mäntele, Werner

    2017-09-01

    We have recently reported infrared spectroscopy of human skin in vivo using quantum cascade laser excitation and photoacoustic or photothermal detection for non-invasive glucose measurement . Here, we analyze the IR light diffusely reflected from skin layers for spectral contributions of glucose. Excitation of human skin by an external cavity tunable quantum cascade laser in the spectral region from 1000 to 1245 cm- 1, where glucose exhibits a fingerprint absorption, yields reflectance spectra with some contributions from glucose molecules. A simple three-layer model of skin was used to calculate the scattering intensities from the surface and from shallow and deeper layers using the Boltzmann radiation transfer equation. Backscattering of light at wavelengths around 10 μm from the living skin occurs mostly from the Stratum corneum top layers and the shallow layers of the living epidermis. The analysis of the polarization of the backscattered light confirms this calculation. Polarization is essentially unchanged; only a very small fraction (< 3%) is depolarized at 90° with respect to the laser polarization set at 0°. Based on these findings, we propose that the predominant part of the backscattered light is due to specular reflectance and to scattering from layers close to the surface. Diffusely reflected light from deeper layers undergoing one or more scattering processes would appear with significantly altered polarization. We thus conclude that a non-invasive glucose measurement based on backscattering of IR light from skin would have the drawback that only shallow layers containing some glucose at concentrations only weakly related to blood glucose are monitored.

  5. Study of {sup 60}Co as gamma source in backscatter gamma densitometers

    Energy Technology Data Exchange (ETDEWEB)

    Gholipour Peyvandi, R.; Taheri, A.; Rahmanzadeh Tootkaleh, S.; Askari Lehdarboni, M. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Islami Rad, S.Z. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Univ. of Qom (Iran, Islamic Republic of). Dept. of Physic

    2015-07-15

    In this work the performance of backscatter gamma densitometer is studied using {sup 60}Co as gamma source. The ability of the densitometer to determine the liquid's interfaces in multi-phase flows was assessed. The aim mainly was to investigate the possibility of using {sup 60}Co in this system. Furthermore, a comparison between {sup 60}Co and was done. The obtained results indicate that {sup 60}Co can be advantageous in this regard.

  6. Comparisons of aerosol backscatter using satellite and ground lidars: implications for calibrating and validating spaceborne lidar.

    Science.gov (United States)

    Gimmestad, Gary; Forrister, Haviland; Grigas, Tomas; O'Dowd, Colin

    2017-02-15

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the polar orbiter Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is an elastic backscatter lidar that produces a global uniformly-calibrated aerosol data set. Several Calibration/Validation (Cal/Val) studies for CALIOP conducted with ground-based lidars and CALIOP data showed large aerosol profile disagreements, both random and systematic. In an attempt to better understand these problems, we undertook a series of ground-based lidar measurements in Atlanta, Georgia, which did not provide better agreement with CALIOP data than the earlier efforts, but rather prompted us to investigate the statistical limitations of such comparisons. Meaningful Cal/Val requires intercomparison data sets with small enough uncertainties to provide a check on the maximum expected calibration error. For CALIOP total attenuated backscatter, reducing the noise to the required level requires averaging profiles along the ground track for distances of at least 1,500 km. Representative comparison profiles often cannot be acquired with ground-based lidars because spatial aerosol inhomogeneities introduce systematic error into the averages. These conclusions have implications for future satellite lidar Cal/Val efforts, because planned satellite lidars measuring aerosol backscatter, wind vector, and CO2 concentration profiles may all produce data requiring considerable along-track averaging for meaningful Cal/Val.

  7. Backscattering of linearly polarized light from turbid tissue-like scattering medium with rough surface

    Science.gov (United States)

    Doronin, Alexander; Tchvialeva, Lioudmila; Markhvida, Igor; Lee, Tim K.; Meglinski, Igor

    2016-07-01

    In the framework of further development of a unified computational tool for the needs of biomedical optics, we introduce an electric field Monte Carlo (MC) model for simulation of backscattering of coherent linearly polarized light from a turbid tissue-like scattering medium with a rough surface. We consider the laser speckle patterns formation and the role of surface roughness in the depolarization of linearly polarized light backscattered from the medium. The mutual phase shifts due to the photons' pathlength difference within the medium and due to reflection/refraction on the rough surface of the medium are taken into account. The validation of the model includes the creation of the phantoms of various roughness and optical properties, measurements of co- and cross-polarized components of the backscattered/reflected light, its analysis and extensive computer modeling accelerated by parallel computing on the NVIDIA graphics processing units using compute unified device architecture (CUDA). The analysis of the spatial intensity distribution is based on second-order statistics that shows a strong correlation with the surface roughness, both with the results of modeling and experiment. The results of modeling show a good agreement with the results of experimental measurements on phantoms mimicking human skin. The developed MC approach can be used for the direct simulation of light scattered by the turbid scattering medium with various roughness of the surface.

  8. Retrieving Marine Inherent Optical Properties from Satellites Using Temperature and Salinity-dependent Backscattering by Seawater

    Science.gov (United States)

    Werdell, Paul J.; Franz, Bryan Alden; Lefler, Jason Travis; Robinson, Wayne D.; Boss, Emmanuel

    2013-01-01

    Time-series of marine inherent optical properties (IOPs) from ocean color satellite instruments provide valuable data records for studying long-term time changes in ocean ecosystems. Semi-analytical algorithms (SAAs) provide a common method for estimating IOPs from radiometric measurements of the marine light field. Most SAAs assign constant spectral values for seawater absorption and backscattering, assume spectral shape functions of the remaining constituent absorption and scattering components (e.g., phytoplankton, non-algal particles, and colored dissolved organic matter), and retrieve the magnitudes of each remaining constituent required to match the spectral distribution of measured radiances. Here, we explore the use of temperature- and salinity-dependent values for seawater backscattering in lieu of the constant spectrum currently employed by most SAAs. Our results suggest that use of temperature- and salinity-dependent seawater spectra elevate the SAA-derived particle backscattering, reduce the non-algal particles plus colored dissolved organic matter absorption, and leave the derived absorption by phytoplankton unchanged.

  9. A radar backscattering mechanism of ocean surface in response to rainfall

    Science.gov (United States)

    Liu, Xinan; Zheng, Quanan; Liu, Ren; Duncan, James H.

    2012-11-01

    The characteristics of ocean surface in response to rainfall and its radar back-scatter are simultaneously measured in laboratory. The experiment is carried out in a water pool that is 1.22 m by 1.22 m with a water depth of 0.3 m. Artificial rainfall is generated from an array of hypodermic needles. The surface characteristics including crowns, stalks, secondary droplets and ring waves are measured with a cinematic Laser-Induced-Florescence (LIF) technique. Our experimental results show that impinging raindrops on the water surface generate various water surface structures with different relative sizes. Among them stalks and crowns comprise the dominant radar backscattering. On the basis of these laboratory experiments and theories of radar scattering from a rough surface, a near-resonance radar backscattering model for quantifying the dependence of the radar return intensity on rain rate on the ocean surface is developed. The model explains the radar response to rain rate simultaneously observed by C-band ASAR and ground-based weather radar. The physical model provides reasonable mechanisms to explain the frequency dependence and polarization behavior of radar signatures from rain cells on the ocean surface. This work is supported by the National Science Foundation, Division of Ocean Sciences under grant OCE962107.

  10. A system-based approach to modeling the ultrasound signal backscattered by red blood cells.

    Science.gov (United States)

    Fontaine, I; Bertrand, M; Cloutier, G

    1999-11-01

    A system-based model is proposed to describe and simulate the ultrasound signal backscattered by red blood cells (RBCs). The model is that of a space-invariant linear system that takes into consideration important biological tissue stochastic scattering properties as well as the characteristics of the ultrasound system. The formation of the ultrasound signal is described by a convolution integral involving a transducer transfer function, a scatterer prototype function, and a function representing the spatial arrangement of the scatterers. The RBCs are modeled as nonaggregating spherical scatterers, and the spatial distribution of the RBCs is determined using the Percus-Yevick packing factor. Computer simulations of the model are used to study the power backscattered by RBCs as a function of the hematocrit, the volume of the scatterers, and the frequency of the incident wave (2-500 MHz). Good agreement is obtained between the simulations and theoretical and experimental data for both Rayleigh and non-Rayleigh scattering conditions. In addition to these results, the renewal process theory is proposed to model the spatial arrangement of the scatterers. The study demonstrates that the system-based model is capable of accurately predicting important characteristics of the ultrasound signal backscattered by blood. The model is simple and flexible, and it appears to be superior to previous one- and two-dimensional simulation studies.

  11. Analysis of dose and risk associated with the use of backscatter vans

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Samanda C.A.; Aquino, Josilto O., E-mail: scorrea@cnen.gov.b, E-mail: josilto@cnen.gov.b [Comissao Nacional de Energia Nuclear (DIAPI/CGMI/CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao Geral de Instalacoes Medicas e Industriais. Div. de Aplicacoes Industriais; Souza, Edmilson M., E-mail: emonteiro@nuclear.ufrj.b [Centro Universitario Estadual da Zona Oeste (CAPI/UEZO), Rio de Janeiro, RJ (Brazil); Silva, Ademir X., E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2011-07-01

    In recent years, imaging technology using radiation has been gaining in importance for the screening of persons for security reasons and in order to detect contraband. And currently, new X-ray detection technologies have been introduced such as the Backscatter Van. The Backscatter Van is used in port and border security, force protection, urban surveillance, and other critical security applications in order to seize drugs, explosives, and more. The system is mobile, affordable and the faster, more effective, and less expensive than any mobile screening solution in the marketplace. However, although the application of this equipment in the national security area is indeed relevant, its use has caused a great deal of controversy, especially with regard to the doses absorbed and to the cancer induction risk associated with these exposures. The aim of this study is to use the Monte Carlo MCNPX code and the male adult voxel (MAX) and female adult voxel (FAX) phantoms, to evaluate the absorbed dose, effective dose and cancer induction risk values associated with the exposures of individuals submitted to Backscatter Van. The effective dose values were calculated as recommended by the new ICRP 103 and the cancer induction risk values were estimated through the BEIR VII document. (author)

  12. An adaptive ultrasonic backscattered signal processing technique for instantaneous characteristic frequency detection.

    Science.gov (United States)

    Jin, Bo; Vai, Mang I

    2014-01-01

    Ultrasonic diagnosis that is convenient and nondestructive to the human body is widely used in medicine. In clinical, ultrasonic backscattered signals characteristics are utilized to acquire information of the human body tissues to perform diagnosis. In this paper, an adaptive ultrasonic backscattered signal processing technique for instantaneous characteristic frequency detection based on the marginal spectrum is presented. In the beginning, the ultrasonic backscattered signal is decomposed into a series of intrinsic mode functions (IMFs) by the Ensemble Empirical Mode Decomposition (EEMD) algorithm. Then the Hilbert spectrum is gained by the Hilbert transform on the IMFs decomposed and screened. Finally, the time-frequency information in the Hilbert spectrum is utilized to extract the instantaneous characteristic frequency based on the marginal spectrum features to detect the objective. With this technique, the spacing between tissues can be estimated for tissue characterization by processing multiple echoes even in the complicated environment. In the simulation study, comparing with the FFT, the technique presented shows its strong noise immunity and indicates its validity in instantaneous characteristic frequency detection.

  13. Effects of Spatial Sampling Interval on Roughness Parameters and Microwave Backscatter over Agricultural Soil Surfaces

    Directory of Open Access Journals (Sweden)

    Matías Ernesto Barber

    2016-06-01

    Full Text Available The spatial sampling interval, as related to the ability to digitize a soil profile with a certain number of features per unit length, depends on the profiling technique itself. From a variety of profiling techniques, roughness parameters are estimated at different sampling intervals. Since soil profiles have continuous spectral components, it is clear that roughness parameters are influenced by the sampling interval of the measurement device employed. In this work, we contributed to answer which sampling interval the profiles needed to be measured at to accurately account for the microwave response of agricultural surfaces. For this purpose, a 2-D laser profiler was built and used to measure surface soil roughness at field scale over agricultural sites in Argentina. Sampling intervals ranged from large (50 mm to small ones (1 mm, with several intermediate values. Large- and intermediate-sampling-interval profiles were synthetically derived from nominal, 1 mm ones. With these data, the effect of sampling-interval-dependent roughness parameters on backscatter response was assessed using the theoretical backscatter model IEM2M. Simulations demonstrated that variations of roughness parameters depended on the working wavelength and was less important at L-band than at C- or X-band. In any case, an underestimation of the backscattering coefficient of about 1-4 dB was observed at larger sampling intervals. As a general rule a sampling interval of 15 mm can be recommended for L-band and 5 mm for C-band.

  14. Theory of anomalous backscattering in second harmonic X-mode ECRH experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gusakov, E. Z.; Popov, A. Yu. [Ioffe Institute, 26 Polytekhnicheskaya st., St. Petersburg 194021 (Russian Federation)

    2016-08-15

    A quantitative model explaining generation of the anomalous backscattering signal in the second harmonic X-mode electron cyclotron resonance heating (ECRH) experiments at TEXTOR tokamak as a secondary nonlinear process which accompanies a primary low-threshold parametric decay instability (PDI) leading to excitation of two—upper hybrid (UH)—plasmons trapped in plasma is developed. The primary absolute PDI enhancing the UH wave fluctuations from the thermal noise level is supposed to be saturated due to a cascade of secondary low-threshold decays of the daughter UH wave leading to excitation of the secondary UH waves down-shifted in frequency and the ion Bernstein wave. A set of equations describing the cascade is derived and solved numerically. The results of numerical modelling are shown to be in agreement with the analytical estimations of the growth rate of the initial and secondary parametric decays and the saturation level. The generation of backscattering signal is explained by coupling of the daughter UH waves. The fine details of the frequency spectrum of the anomalously reflected extraordinary wave and the absolute value of the observed backscattering signal in the second harmonic X-mode ECRH experiments at TEXTOR are reproduced.

  15. Electrochemical cell structure including an ionomeric barrier

    Science.gov (United States)

    Lambert, Timothy N.; Hibbs, Michael

    2017-06-20

    An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

  16. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive......, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established...

  17. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen......Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...

  18. Building micro and nanosystems with electrochemical discharges

    Energy Technology Data Exchange (ETDEWEB)

    Wuethrich, Rolf, E-mail: wuthrich@encs.concordia.c [Department of Mechanical and Industrial Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, QC (Canada); Allagui, Anis [Department of Mechanical and Industrial Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, QC (Canada)

    2010-11-30

    Since the discovery of the electrochemical discharge phenomenon by Fizeau and Foucault, several contributions have expanded the wide range of applications associated with this high current density electrochemical process. The complexity of the phenomenon, from the macroscopic to the microscopic scales, led since then to experimental and theoretical studies from different research fields. This contribution reviews the chemical and electrochemical perspectives where a mechanistic model based on results from radiation chemistry of aqueous solutions is proposed. In addition applications to micro-machining and fabrication of nanoparticles are discussed.

  19. NOAA TIFF Graphic - 0.5 meter Backscatter Mosaic of St. John, U.S. Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the southern shore of St. John, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  20. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geotiff represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography...

  1. NOAA ESRI Geotiff - 3m Backscatter Mosaic, Puerto Rico (Isla de Vieques) - UTM 20N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 3 meter resolution backscatter mosaic of selected portions of seafloor around Isla de Vieques, Puerto Rico. NOAA's NOS/NCCOS/CCFHR, in...

  2. CRED Reson 8101 multibeam backscatter data of Jarvis Island, Pacific Remote Island Areas, Central Pacific in netCDF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Jarvis Atoll, Pacific Island Areas, Central Pacific. These...

  3. CRED Reson 8101 multibeam backscatter data of Howland Island, Pacific Remote Island Areas, Central Pacific in netCDF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Howland Island, Pacific Island Areas, Central Pacific. These...

  4. Simulation of L-band and HH microwave backscattering from coniferous forest stands - A comparison with SIR-B data

    Science.gov (United States)

    Sun, Guo-Qing; Simonett, David S.

    1988-01-01

    SIR-B images of the Mt. Shasta region of northern California are used to evaluate a composite L-band HH backscattering model of coniferous forest stands. It is found that both SIR-B and simulated backscattering coefficients for eight stands studied have similar trends and relations to average tree height and average number of trees per pixel. Also, the dispersion and distribution of simulated backscattering coefficients from each stand broadly match SIR-B data from the same stand. Although the limited quality and quantity of experimental data makes it difficult to draw any strong conclusions, the comparisons indicate that a stand-based L-band HH composite model seems promising for explaining backscattering features.

  5. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 1 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team...

  6. NOAA TIFF Image - 4m Multibeam Backscatter for Red Snapper Research Areas in the South Atlantic Bight, 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains unified Multibeam Backscatter GeoTiffs with 4x4 meter cell resolution describing the geomorphology of 15 areas along the shelf edge off the...

  7. L-Band SAR Backscatter Related to Forest Cover, Height and Aboveground Biomass at Multiple Spatial Scales across Denmark

    National Research Council Canada - National Science Library

    Neha P Joshi; Edward T A Mitchard; Johannes Schumacher; Vivian K Johannsen; Sassan Saatchi; Rasmus Fensholt

    2015-01-01

    .... Here, we attempt to quantify the effect of these factors by relating L-band ALOS PALSAR HV backscatter and unique country-wide LiDAR-derived maps of vegetation penetrability, height and AGB over...

  8. Wintertime water dynamics and moonlight disruption of the acoustic backscatter diurnal signal in an ice‐covered Northeast Greenland fjord

    National Research Council Canada - National Science Library

    Petrusevich, Vladislav; Dmitrenko, Igor A; Kirillov, Sergey A; Rysgaard, Søren; Falk‐Petersen, Stig; Barber, David G; Boone, Wieter; Ehn, Jens K

    2016-01-01

    Six and a half month records from three ice‐tethered Acoustic Doppler Current Profilers deployed in October 2013 in Young Sound fjord in Northeast Greenland are used to analyze the acoustic backscatter signal...

  9. CRED Reson 8101 multibeam backscatter data of Johnston Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the lagoon, shelf, and slope environments of Palmyra Atoll, Pacific Island Areas, Central Pacific....

  10. Reson 8101 multibeam backscatter data from portions of the banktop and bank edge environments at Midway Atoll, Hawaii, USA.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of Midway Atoll, Northwestern Hawaiian Islands, USA. These data provide coverage between 0 and 200...

  11. Acoustic Backscatter of the Sacramento River, from the Feather River to Knights Landing, California in February 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents acoustic backscatter data collected on February 1, 2011, in the Sacramento River from the confluence of the Feather River to...

  12. NOAA ESRI Geotiff - 3m Backscatter Mosaic, Puerto Rico (Isla de Vieques) - UTM 20N NAD83 (NCEI Accession 0131852)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 3 meter resolution backscatter mosaic of selected portions of seafloor around Isla de Vieques, Puerto Rico. NOAA's NOS/NCCOS/CCFHR, in...

  13. NOAA TIFF Image - 3m Backscatter Mosaic, Florida Deep Coral Areas - Lost Coast Explorer - (2010), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 3x3 meter cell size representing the backscatter (intensity) of several deep coral priority areas off the Atlantic Coast...

  14. Backscatter Mosaic used to identify, delineate and classify moderate-depth benthic habitats around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 2x2 meter resolution backscatter mosaic of the moderate-depth portion of the NPS's Virgin Islands Coral Reef National Monument, south of St....

  15. NOAA TIFF Image - 50m Backscatter, Charleston Bump - Deep Coral Priority Areas - Nancy Foster - (2006), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 30x30 meter cell size representing the backscatter intensity of the Charleston Bump off of the South Atlantic Bight,...

  16. The range and intensity of backscattered electrons for use in the creation of high fidelity electron beam lithography patterns.

    Science.gov (United States)

    Czaplewski, David A; Holt, Martin V; Ocola, Leonidas E

    2013-08-02

    We present a set of universal curves that predict the range and intensity of backscattered electrons which can be used in conjunction with electron beam lithography to create high fidelity nanoscale patterns. The experimental method combines direct write dose, backscattered dose, and a self-reinforcing pattern geometry to measure the dose provided by backscattered electrons to a nanoscale volume on the substrate surface at various distances from the electron source. Electron beam lithography is used to precisely control the number and position of incident electrons on the surface of the material. Atomic force microscopy is used to measure the height of the negative electron beam lithography resist. Our data shows that the range and the intensity of backscattered electrons can be predicted using the density and the atomic number of any solid material, respectively. The data agrees with two independent Monte Carlo simulations without any fitting parameters. These measurements are the most accurate electron range measurements to date.

  17. The range and intensity of backscattered electrons for use in the creation of high fidelity electron beam lithography patterns

    Science.gov (United States)

    Czaplewski, David A.; Holt, Martin V.; Ocola, Leonidas E.

    2013-08-01

    We present a set of universal curves that predict the range and intensity of backscattered electrons which can be used in conjunction with electron beam lithography to create high fidelity nanoscale patterns. The experimental method combines direct write dose, backscattered dose, and a self-reinforcing pattern geometry to measure the dose provided by backscattered electrons to a nanoscale volume on the substrate surface at various distances from the electron source. Electron beam lithography is used to precisely control the number and position of incident electrons on the surface of the material. Atomic force microscopy is used to measure the height of the negative electron beam lithography resist. Our data shows that the range and the intensity of backscattered electrons can be predicted using the density and the atomic number of any solid material, respectively. The data agrees with two independent Monte Carlo simulations without any fitting parameters. These measurements are the most accurate electron range measurements to date.

  18. CRED Reson 8101 multibeam backscatter data of Baker Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Baker Island, Pacific Island Areas, Central Pacific. These...

  19. Simrad EM300 multibeam backscatter data from portions of the banktop and bank edge environments at Kure Atoll, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of Kure Atoll, Northwestern Hawaiian Islands, USA. These data provide coverage between 0 and 2000...

  20. CRED Simrad em300 multibeam backscatter data from the islands and banks in the Mariana archipelago, 2007.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the Mariana archipelago between the U.S. Territory of Guam and Uracas Island in the Commonwealth...