WorldWideScience

Sample records for backscattering

  1. Dynamic coherent backscattering mirror

    Energy Technology Data Exchange (ETDEWEB)

    Zeylikovich, I.; Xu, M., E-mail: mxu@fairfield.edu [Physics Department, Fairfield University, Fairfield, CT 06824 (United States)

    2016-02-15

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

  2. Dynamic coherent backscattering mirror

    Science.gov (United States)

    Xu, M.

    2016-01-01

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation. PMID:26937296

  3. THERMAL NEUTRON BACKSCATTER IMAGING.

    Energy Technology Data Exchange (ETDEWEB)

    VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

    2004-10-16

    Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

  4. 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 –...

  5. 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...

  6. Detection of Coaxial Backscattered Electrons in SEM

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the iow energy backscattered electrons and collect the backscattered electrons, which are backscattered close to the incident beam orientation. The main advantage of this geometry is adapted to topographic contrast attenuation and atomic number contrast enhancement. Thus this new SEM is very suitable to analyze the material composition.

  7. Ultrasonic backscatter from cancellous bone: the apparent backscatter transfer function.

    Science.gov (United States)

    Hoffmeister, Brent K; Mcpherson, Joseph A; Smathers, Morgan R; Spinolo, P Luke; Sellers, Mark E

    2015-12-01

    Ultrasonic backscatter techniques are being developed to detect changes in cancellous bone caused by osteoporosis. Many techniques are based on measurements of the apparent backscatter transfer function (ABTF), which represents the backscattered power from bone corrected for the frequency response of the measurement system. The ABTF is determined from a portion of the backscatter signal selected by an analysis gate of width τw delayed by an amount τd from the start of the signal. The goal of this study was to characterize the ABTF for a wide range of gate delays (1 μs ≤ τd ≤ 6 μs) and gate widths (1 μs ≤ τw ≤ 6 μs). Measurements were performed on 29 specimens of human cancellous bone in the frequency range 1.5 to 6.0 MHz using a broadband 5-MHz transducer. The ABTF was found to be an approximately linear function of frequency for most choices of τd and τw. Changes in τd and τw caused the frequency-averaged ABTF [quantified by apparent integrated backscatter (AIB)] and the frequency dependence of the ABTF [quantified by frequency slope of apparent backscatter (FSAB)] to change by as much as 24.6 dB and 6.7 dB/MHz, respectively. τd strongly influenced the measured values of AIB and FSAB and the correlation of AIB with bone density (-0.95 ≤ R ≤ +0.68). The correlation of FSAB with bone density was influenced less strongly by τd (-0.97 ≤ R ≤ -0.87). τw had a weaker influence than τd on the measured values of AIB and FSAB and the correlation of these parameters with bone density.

  8. 3D Backscatter Imaging System

    Science.gov (United States)

    Turner, D. Clark (Inventor); Whitaker, Ross (Inventor)

    2016-01-01

    Systems and methods for imaging an object using backscattered radiation are described. The imaging system comprises both a radiation source for irradiating an object that is rotationally movable about the object, and a detector for detecting backscattered radiation from the object that can be disposed on substantially the same side of the object as the source and which can be rotationally movable about the object. The detector can be separated into multiple detector segments with each segment having a single line of sight projection through the object and so detects radiation along that line of sight. Thus, each detector segment can isolate the desired component of the backscattered radiation. By moving independently of each other about the object, the source and detector can collect multiple images of the object at different angles of rotation and generate a three dimensional reconstruction of the object. Other embodiments are described.

  9. Fundamentals of Acoustic Backscatter Imagery

    Science.gov (United States)

    2011-09-20

    41 6.12 Geocoding ...47 7.6 Errors in Geocoding .............................................................................................................. 47...h = z - R cos6 (39a) and x = rt sin6. (39b) 6.12 Geocoding Acoustic backscatter imagery data are collected by recording the across-track signals

  10. X-ray backscatter imaging

    Science.gov (United States)

    Dinca, Dan-Cristian; Schubert, Jeffrey R.; Callerame, J.

    2008-04-01

    In contrast to transmission X-ray imaging systems where inspected objects must pass between source and detector, Compton backscatter imaging allows both the illuminating source as well as the X-ray detector to be on the same side of the target object, enabling the inspection to occur rapidly and in a wide variety of space-constrained situations. A Compton backscatter image is similar to a photograph of the contents of a closed container, taken through the container walls, and highlights low atomic number materials such as explosives, drugs, and alcohol, which appear as especially bright objects by virtue of their scattering characteristics. Techniques for producing X-ray images based on Compton scattering will be discussed, along with examples of how these systems are used for both novel security applications and for the detection of contraband materials at ports and borders. Differences between transmission and backscatter images will also be highlighted. In addition, tradeoffs between Compton backscatter image quality and scan speed, effective penetration, and X-ray source specifications will be discussed.

  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. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. Nodule bottom backscattering study using multibeam echosounder

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Raju, Y.S.N.; 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...

  3. 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.

  4. Hanle effect in coherent backscattering

    CERN Document Server

    Labeyrie, G; Müller, C A; Sigwarth, O; Delande, D; Kaiser, R

    2002-01-01

    We study the shape of the coherent backscattering (CBS) cone obtained when resonant light illuminates a thick cloud of laser-cooled rubidium atoms in presence of a homogenous magnetic field. We observe new magnetic field-dependent anisotropies in the CBS signal. We show that the observed behavior is due to the modification of the atomic radiation pattern by the magnetic field (Hanle effect in the excited state).

  5. Monte-Carlo simulation of backscattered electrons in Auger electron spectroscopy. Part 1: Backscattering factor calculation

    Energy Technology Data Exchange (ETDEWEB)

    Tholomier, M.; Vicario, E.; Doghmane, N.

    1987-10-01

    The contribution of backscattered electrons to Auger electrons yield was studied with a multiple scattering Monte-Carlo simulation. The Auger backscattering factor has been calculated in the 5 keV-60 keV energy range. The dependence of the Auger backscattering factor on the primary energy and the beam incidence angle were determined. Spatial distributions of backscattered electrons and Auger electrons are presented for a point incident beam. Correlations between these distributions are briefly investigated.

  6. Averaging of Backscatter Intensities in Compounds

    Science.gov (United States)

    Donovan, John J.; Pingitore, Nicholas E.; Westphal, Andrew J.

    2002-01-01

    Low uncertainty measurements on pure element stable isotope pairs demonstrate that mass has no influence on the backscattering of electrons at typical electron microprobe energies. The traditional prediction of average backscatter intensities in compounds using elemental mass fractions is improperly grounded in mass and thus has no physical basis. We propose an alternative model to mass fraction averaging, based of the number of electrons or protons, termed “electron fraction,” which predicts backscatter yield better than mass fraction averaging. PMID:27446752

  7. 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)

  8. Spectral variability of the particulate backscattering ratio

    Science.gov (United States)

    Whitmire, A. L.; Boss, E.; Cowles, T. J.; Pegau, W. S.

    2007-05-01

    The spectral dependency of the particulate backscattering ratio is relevant in the fields of ocean color inversion, light field modeling, and inferring particle properties from optical measurements. Aside from theoretical predictions for spherical, homogeneous particles, we have very limited knowledge of the actual in situ spectral variability of the particulate backscattering ratio. This work presents results from five research cruises that were conducted over a three-year period. Water column profiles of physical and optical properties were conducted across diverse aquatic environments that offered a wide range of particle populations. The main objective of this research was to examine the behavior of the spectral particulate backscattering ratio in situ, both in terms of its absolute magnitude and its variability across visible wavelengths, using over nine thousand 1-meter binned data points for each of five wavelengths of the spectral particulate backscattering ratio. Our analysis reveals no spectral dependence of the particulate backscattering ratio within our measurement certainty, and a geometric mean value of 0.013 for this dataset. This is lower than the commonly used value of 0.0183 from Petzold’s integrated volume scattering data. Within the first optical depth of the water column, the mean particulate backscattering ratio was 0.010.

  9. Reducing parametric backscattering by polarization rotation

    Science.gov (United States)

    Barth, Ido; Fisch, Nathaniel J.

    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 employing lasers 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. However, in identifying the source of the backscatter reduction, it is difficult to disentangle the rotating polarization from the frequency separation based approach used to engineer the beam's polarization. Although the backscatter reduction arises similarly to other approaches that employ frequency separation, in the case here, the intensity remains constant in time.

  10. Incidence angle normalization of radar backscatter data

    Science.gov (United States)

    NASA’s Soil Moisture Passive Active (SMAP) satellite (~2014) will include a radar system that will provide L-band multi-polarization backscatter at a constant incidence angle of 40º. During the pre-launch phase of the project there is a need for observations that will support the radar-based soil mo...

  11. Method for analysis of low energy backscattering spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hnatowicz, V.; Kvitek, J. (Ceskoslovenska Akademie Ved, Rez. Ustav Jaderne Fyziky); Pelikan, L. (Ceske Vysoke Uceni Technicke, Prague (Czechoslavika). Dept. of Microelectronics); Rybka, V.; Krejci, P. (Tesla, Prague (Czechoslovakia))

    1982-04-15

    An analytical formula is proposed describing the shape of the energy spectra of particles backscattered from samples implanted with heavy impurities. The method is suitable for quantitative evaluation of backscattering spectra measured with low energy ions.

  12. 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...

  13. 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...

  14. Backscatter B [7125]--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...

  15. 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...

  16. 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...

  17. 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...

  18. Backscatter B [Swath]--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...

  19. Backscatter A [8101]--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...

  20. Backscatter A [8101]--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. 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...

  2. 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...

  3. 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...

  4. 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...

  5. Backscatter C [Swath]--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...

  6. 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...

  7. 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...

  8. Backscatter B [7125]--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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Backscatter A [8101]--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...

  1. 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...

  2. 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.

    of Oceanography to convert the measured electrical energy into acoustic backscatter energy. This conversion includes corrections for the position, slope, and area of the scattering surface. In this paper we present backscatter data from several areas surveyed...

  3. 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...

  4. 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...

  5. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

    Science.gov (United States)

    Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-07-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

  6. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II:Electromagnetic backscattering model

    Institute of Scientific and Technical Information of China (English)

    谢涛; William Perrie; 赵尚卓; 方贺; 于文金; 何宜军

    2016-01-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface.

  7. Spectra of Particulate Backscattering in Natural Waters

    Science.gov (United States)

    Gordon, Howard, R.; Lewis, Marlon R.; McLean, Scott D.; Twardowski, Michael S.; Freeman, Scott A.; Voss, Kenneth J.; Boynton, Chris G.

    2009-01-01

    Hyperspectral profiles of downwelling irradiance and upwelling radiance in natural waters (oligotrophic and mesotrophic) are combined with inverse radiative transfer to obtain high resolution spectra of the absorption coefficient (a) and the backscattering coefficient (bb) of the water and its constituents. The absorption coefficient at the mesotrophic station clearly shows spectral absorption features attributable to several phytoplankton pigments (Chlorophyll a, b, c, and Carotenoids). The backscattering shows only weak spectral features and can be well represented by a power-law variation with wavelength (lambda): b(sub b) approx. Lambda(sup -n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(sub b), suggest that it is depressed in spectral regions of strong particle absorption. The applicability of the present inverse radiative transfer algorithm, which omits the influence of Raman scattering, is limited to lambda < 490 nm in oligotrophic waters and lambda < 575 nm in mesotrophic waters.

  8. Low-Frequency Electromagnetic Backscattering from Tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Casey, K; Pao, H

    2007-01-16

    Low-frequency electromagnetic scattering from one or more tunnels in a lossy dielectric half-space is considered. The tunnel radii are assumed small compared to the wavelength of the electromagnetic field in the surrounding medium; a tunnel can thus be modeled as a thin scatterer, described by an equivalent impedance per unit length. We examine the normalized backscattering width for cases in which the air-ground interface is either smooth or rough.

  9. 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.

  10. Backscattering Differential Ghost Imaging in Turbid Media

    CERN Document Server

    Bina, M; Molteni, M; Gatti, A; Lugiato, L A; Ferri, F

    2012-01-01

    In this Letter we present experimental results concerning the retrieval of images of absorbing objects immersed in turbid media via differential ghost imaging (DGI) in a backscattering configuration. The method has been applied, for the first time to our knowledge, to the imaging of small thin black objects located at different depths inside a turbid solution of polystyrene nanospheres and its performances assessed via comparison with standard imaging techniques. A simple theoretical model capable of describing the basic optics of DGI in turbid media is proposed.

  11. 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......, a cod (Gadus morhua) was scanned with both a BK Medical ProFocus 2202 ultrasound scanner and a Toshiba Aquilion ONE computed tomography (CT) scanner. The US images of the fis were compared with US images created using the ultrasound simulation program Field II. The center frequency of the transducer...

  12. 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.

  13. Sea Floor Analyses Based On Multibeam Backscatter Strength

    Science.gov (United States)

    Beyer, A.

    Measurements of acoustic backscatter strength can be applied to analyse sea floor coverage on a spatial extent. They provide consistent coverage compared to analy- ses based on only a few surface samples. In particular the spatial validity of surface samples can be determined by analyses based on acoustic backscatter strength and sampling locations representative for the surrounding area can be determined. Dur- ing the cruise ANTXVII/4 of the German RV "Polarstern", a high precision swath bathymetry survey was performed along the European continental margin in the Por- cupine Seabight off southwest Ireland. Within the Porcupine Seabight a number of mound structures have been discovered earlier, most of them being carbonate mounds. The structure and genesis of these mounds are the main objective of recent investiga- tions. The cruise and the subsequent investigations are part of the EU project GEO- MOUND. They focus on the Belgica mound province. Besides the depth measure- ments, the acoustic intensities of the received echos have been recorded. Taking into account the transmitted and received sound level, acoustic beam patterns, and acous- tic attenuation in the water column, the backscatter strength of the ensonified area was calculated. This backscatter information is used to analyse the sea floor cover- age. Based on the data of the systematic survey the spatial variation of the backscatter strength was derived. Regions of equal backscatter characteristic can be combined and functions showing the dependency between backscatter strength and incidence angle of the acoustic wave can be determined. These functions help interpreting sea floor coverage. The mapping of the backscatter strength of the mound area indicates clear changes in backscatter strength. Small and shallow channels show a lower backscat- ter strength than their surroundings. That means the surface coverage of the channels is smooth with respect to the surroundings. One interpretation of this

  14. Demonstration of zero optical backscattering from single nanoparticles

    CERN Document Server

    Person, Steven; Lapin, Zachary; Saenz, Juan Jose; Wicks, Gary; Novotny, Lukas

    2012-01-01

    We present the first experimental demonstration of zero backscattering from nanoparticles at op- tical frequencies as originally discussed by Kerker et. al. [M. Kerker, D. Wang, and C. Giles, J. Opt. Soc. A 73, 765 (1983)]. GaAs pillars were fabricated on a fused silica substrate and the spectrum of the backscattered radiation was measured in the wavelength range 600-1000 nm. Suppression of backscattering occurred at ~725 nm, agreeing with calculations based on the discrete dipole approximation. Particles with zero backscattering provide new functionality for metamaterials and optical antennas.

  15. CRED Acoustic Backscatter Guam 2003, Imagery Extracted from Gridded Bathymetry

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter extracted from gridded bathymetry of the banktops and shelf environments of Guam, of the Mariana Islands Archipelago.

  16. Radar backscatter properties of milo and soybeans

    Science.gov (United States)

    Bush, T. F.; Ulaby, F. T.; Metzler, T.

    1975-01-01

    The radar backscatter from fields of milo and soybeans was measured with a ground based radar as a function of frequency (8-18 GHz), polarization (HH and VV) and angle of incidence (0 deg-70 deg) during the summer of 1974. Supporting ground truth was gathered contemporaneously with the backscatter data. At nadir sigma deg of milo correlated highly, r = 0.96, with soil moisture in the milo field at 8.6 GHz but decreased to a value of r = 0.78 at a frequency of 17.0 GHz. Correlation studies of the variations of sigma deg with soil moisture in the soybean fields were not possible due to a lack of a meaningful soil moisture dynamic range. At the larger angles of incidence, however, sigma deg of soybeans did appear to be dependent on precipitation. It is suggested this phenomenon was caused by the rain altering plant geometry. In general sigma deg of both milo and soybeans had a relatively small dynamic range at the higher angles of incidence and showed no significant dependence on the measured crop parameters.

  17. 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.

  18. Coherent Backscattering of Ultra-cold Atoms

    CERN Document Server

    Jendrzejewski, Fred; Richard, Jérémie; Date, Aditya; Plisson, Thomas; Bouyer, Philippe; Aspect, Alain; Josse, Vincent

    2012-01-01

    We report on the direct observation of coherent backscattering (CBS) of ultra-cold atoms, in a quasi two dimensional configuration. Launching atoms with a well defined momentum in a laser speckle disordered potential, we follow the progressive build up of the momentum scattering pattern, consisting of a ring associated with multiple elastic scattering, and the CBS peak in the backward direction. Monitoring the depletion of the initial momentum component and the formation of the angular ring profile allow us to determine microscopic transport quantities. The time resolved evolution of the CBS peak is studied and is found a fair agreement with predictions, at long times as well as at short times. The observation of CBS can be considered a direct signature of coherence in quantum transport of particles in disordered media. It is responsible for the so called weak localization phenomenon, which is the precursor of Anderson localization.

  19. Electron Backscatter Diffraction in Low Vacuum Conditions

    Energy Technology Data Exchange (ETDEWEB)

    El-Dasher, B S; Torres, S G

    2008-07-17

    Most current scanning electron microscopes (SEMs) have the ability to analyze samples in a low vacuum mode, whereby a partial pressure of water vapor is introduced into the SEM chamber, allowing the characterization of nonconductive samples without any special preparation. Although the presence of water vapor in the chamber degrades electron backscatter diffraction (EBSD) patterns, the potential of this setup for EBSD characterization of nonconductive samples is immense. In this chapter we discuss the requirements, advantages and limitations of low vacuum EBSD (LV-EBSD), and present how this technique can be applied to a two-phase ceramic composite as well as hydrated biominerals as specific examples of when LV-EBSD can be invaluable.

  20. Rutherford backscattering analysis of contaminants in PET

    Science.gov (United States)

    Pierce, D. E.; Pfeffer, R. L.; Sadler, G. D.

    1997-05-01

    Rutherford Backscattering Spectrometry (RBS) was used to understand the sorption and desorption of organic contaminants in the polymer Poly(ethylene terephthalate), or PET. Samples were exposed to a range of organics to simulate contamination of PET that can take place in the post-consumer waste stream. From RBS analysis, concentration depth profiles were shown to vary from a monolayer regime surface layer to a saturation level, depending on the contaminant. Heat treatments were also applied to contaminated polymer to simulate thermal processing steps in the recycling of PET. Heating caused a dramatic decrease in contaminants and in some cases a complete removal of contamination was achieved to the limit of RBS detectability.

  1. 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.

  2. 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.

  3. X-ray backscatter imaging of nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Jeffrey Allen; Gunning, John E; Hollenbach, Daniel F; Ott, Larry J; Shedlock, Daniel

    2014-09-30

    The energy of an X-ray beam and critical depth are selected to detect structural discontinuities in a material having an atomic number Z of 57 or greater. The critical depth is selected by adjusting the geometry of a collimator that blocks backscattered radiation so that backscattered X-ray originating from a depth less than the critical depth is not detected. Structures of Lanthanides and Actinides, including nuclear fuel rod materials, can be inspected for structural discontinuities such as gaps, cracks, and chipping employing the backscattered X-ray.

  4. Portable fluorescence meter with reference backscattering channel

    Science.gov (United States)

    Kornilin, Dmitriy V.; Grishanov, Vladimir N.; Zakharov, Valery P.; Burkov, Dmitriy S.

    2016-09-01

    Methods based on fluorescence and backscattering are intensively used for determination of the advanced glycation end products (AGE) concentration in the biological tissues. There are strong correlation between the AGE concentration and the severity of such diseases like diabetes, coronary heart disease and renal failure. This fact can be used for diagnostic purposes in medical applications. Only few investigations in this area can be useful for development of portable and affordable in vivo AGE meter because the most of them are oriented on using spectrometers. In this study we describe the design and the results of tests on volunteers of portable fluorescence meter based on two photodiodes. One channel of such fluorimeter is used for measurement of the autofluorescence (AF) intensity, another one - for the intensity of elastically scattered radiation, which can be used as a reference. This reference channel is proposed for normalization of the skin autofluorescence signal to the human skin photo type. The fluorimeter, that was developed is relatively compact and does not contain any expensive optical and electronic components. The experimental results prove that proposed tool can be used for the AGE estimation in human skin.

  5. 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...

  6. 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...

  7. Impact of carrier heating on backscattering in inversion layers

    Science.gov (United States)

    Clerc, R.; Palestri, P.; Selmi, L.; Ghibaudo, G.

    2011-11-01

    In this work, Monte Carlo simulations and analytical modeling are used to investigate quasi-ballistic transport in nanometric metal oxide semiconductor field effect transistors (MOSFETs). In particular, we examine how the thermal nature of the distribution functions, which is implicitly assumed in the most common expression for the backscattering coefficient, leads to an underestimation of the backscattering coefficient in high field conditions and erroneous velocity distribution along the channel. An improved analytical model is proposed, which better captures the nonequilibrium nature of the distribution function and its impact on backscattering and by allowing velocity profiles to exceed the thermal limit. The improved model provides additional insights on the impact of several assumptions on backscattering and could serve as the basis for the development of physically based compact models of quasi-ballistic MOSFETs.

  8. 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...

  9. 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....

  10. Detection of buried landmine with X-ray backscatter technique

    Energy Technology Data Exchange (ETDEWEB)

    Yuk, Sunwoo [Department of Electronics and Information Engineering, Korea University, Seoul (Korea, Republic of)]. E-mail: sunwoo@korea.ac.kr; Kim, Kwang Hyun [Chosun University, 375, Seosuk-Dong, Dong-Gu, Gwangju (Korea, Republic of); Yi, Yun [Department of Electronics and Information Engineering, Korea University, Seoul (Korea, Republic of)

    2006-11-30

    We describe a continuously operating scanning X-ray imaging system developed for landmine detection based on a backscatter X-ray principle, thus detection is done from the same side as the source. The source operates at 120 kV p and 3 mA. To study the physics of Compton X-ray backscattering, the photon transport factor, backscatter factor (BSF) and backscatter probability (BSP) were simulated using Monte-Carlo calculations using the generalized particle transport program MCNP. Based on the Monte-Carlo analyses results, a mine detecting system has been designed. It potentially has a low false alarm rate and a high detection probability, and a direct imaging facility.

  11. Backscatter B [USGS]--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...

  12. Backscatter A [CSUMB]--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 of Ventura map area, California. The raster...

  13. 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...

  14. 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...

  15. Aerosol measurement program strategy for global aerosol backscatter model development

    Science.gov (United States)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

  16. Backscatter--Offshore of Refugio Beach Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of SIM 3319 presents data for part of the acoustic-backscatter map (see sheet 3, SIM 3319) of Offshore Refugio Beach map area, California. The raster data...

  17. 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...

  18. 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...

  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. 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...

  1. Analysis of forest backscattering characteristics based on polarization coherence tomography

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    It is difficult to make an inventory of vertical profiles of forest structure parameters in field measurements.However,analysis and understanding of forest backscattering characteristics contribute to estimation and detection of forest vertical structure because of the close relationships between backscattering characteristics and structure parameters.The vertical structure function in the complex interferometric coherence definition,which represents the vertical variation of microwave scattering with the penetration depth at a point in the 2-D radar image and can be used to analyze the forest backscattering characteristics,can be reconstructed from polarization coherence tomography(PCT).Based on PCT,the paper analyzes the forest backscattering characteristics and explores the inherent relationship between the result of PCT and the forest structure parameters from numerical simulation of Random Volume over Ground model(RVoG),Polarimetric SAR interferometry(PolInSAR)simulation of forest scene and PolInSAR data at L-band of the test site Traunstein.Firstly,the effects of the extinction coefficient and surface-to-volume scattering ratio in RVoG model on vertical backscattering characteristics are analyzed by means of numerical simulation.Secondly,by applying PCT to L-band POLInSAR simulations of forest scene,different variations of vertical backscattering due to different extinction coefficients and the ratios of surface-to-volume scattering resulting from different polarizations,forest types and densities are displayed and analyzed.Then a concept of relative average backscattering intensity is presented,and the factors which affect its vertical distribution are also discussed.Preliminary results show that there is high sensitivity of the vertical distribution of forest relative average backscattering intensity to the polarization,forest type and density.Finally,based on repeat pass DLR E-SAR L-band airborne POLInSAR data,the capability of PCT technology for detection

  2. Aerosol Lidar for the Relative Backscatter Amplification Measurements

    Science.gov (United States)

    Razenkov, Igor A.; Banakh, Victor A.; Nadeev, Alexander I.

    2016-06-01

    Backscatter amplification presents only in a turbulent atmosphere, when the laser beam is propagates twice through the same inhomogeneities. We proposed technical solution to detect backscatter amplification. An aerosol micro pulse lidar with a beam expansion via receiving telescope was built to study this effect. Our system allows simultaneous detection of two returns from the same scattering volume: exactly on the axis of the laser beam and off the axis.

  3. A Laboratory Investigation into Microwave Backscattering from Sea Ice

    Science.gov (United States)

    1989-08-01

    froze to form saline slush ice. Continued freezing of * the salty water directly beneath the slush ice led to the formation of columnar-textured...significant influence on backscatter from extremely smooth saline ice at C band. We determined that backscatter at C band from moderately smooth desalinated ...that volume scatter from desalinated ice is important at X band and that it is dominant at Ku band at angles of 100 or more from nadir Conclusions

  4. Criteria of backscattering in chiral one-way photonic crystals

    Science.gov (United States)

    Cheng, Pi-Ju; Chang, Shu-Wei

    2016-03-01

    Optical isolators are important devices in photonic circuits. To reduce the unwanted reflection in a robust manner, several setups have been realized using nonreciprocal schemes. In this study, we show that the propagating modes in a strongly-guided chiral photonic crystal (no breaking of the reciprocity) are not backscattering-immune even though they are indeed insensitive to many types of scatters. Without the protection from the nonreciprocity, the backscattering occurs under certain circumstances. We present a perturbative method to calculate the backscattering of chiral photonic crystals in the presence of chiral/achiral scatters. The model is, essentially, a simplified analogy to the first-order Born approximation. Under reasonable assumptions based on the behaviors of chiral photonic modes, we obtained the expression of reflection coefficients which provides criteria for the prominent backscattering in such chiral structures. Numerical examinations using the finite-element method were also performed and the results agree well with the theoretical prediction. From both our theory and numerical calculations, we find that the amount of backscattering critically depends on the symmetry of scatter cross sections. Strong reflection takes place when the azimuthal Fourier components of scatter cross sections have an order l of 2. Chiral scatters without these Fourier components would not efficiently reflect the chiral photonic modes. In addition, for these chiral propagating modes, disturbances at the most significant parts of field profiles do not necessarily result in the most effective backscattering. The observation also reveals what types of scatters or defects should be avoided in one-way applications of chiral structures in order to minimize the backscattering.

  5. Laser light backscatter from intermediate and high Z plasmas

    Science.gov (United States)

    Berger, R. L.; Constantin, C.; Divol, L.; Meezan, N.; Froula, D. H.; Glenzer, S. H.; Suter, L. J.; Niemann, C.

    2006-09-01

    In experiments at the Omega Laser Facility [J. M. Soures et al., Fusion Technol. 30, 492 (1996)], stimulated Brillouin backscatter (SBS) from gasbags filled with krypton and xenon gases was ten times lower than from CO2-filled gasbags with similar electron densities. The SBS backscatter was a 1%-5% for both 527 and 351nm interaction beams at an intensity of ˜1015W /cm2. The SRS backscatter was less than 1%. The 351nm interaction beam is below the threshold for filamentation and the SBS occurs in the density plateau between the blast waves. Inverse bremsstrahlung absorption of the incident and SBS light account for the lower reflectivity from krypton than from CO2. The 527nm interaction beam filaments in the blowoff plasma before the beam propagates through the blast wave, where it is strongly absorbed. Thus, most of the 527nm SBS occurs in the flowing plasma outside the blast waves.

  6. Effects of optical backscattering on silicon photonic hybrid laser performance

    Science.gov (United States)

    Pacradouni, V.; Klein, J.; Pond, J.

    2016-04-01

    We present numerical results on the effect of backscattering at the junctions of double bus ring resonators in a Vernier ring hybrid laser design. The structure is comprised off a pair of III-V gain media evanescently coupled to a silicon on insulator racetrack comprised of a pair of double bus ring resonators coupled together through straight and flared waveguide sections. We show how the small backscattering at the ring resonator junctions has the effect of splitting and shifting the resonances off the clockwise and counter clockwise propagating modes thereby modifying the feedback spectrum from the ideal case. We then simulate results such as light current (LI) curves, relative intensity noise (RIN) and laser spectrum, and compare the laser performance including backscattering effects with the ideal case.

  7. Backscatter signatures of biological aerosols in the infrared.

    Science.gov (United States)

    Thrush, Evan; Salciccioli, Nicolas; Brown, David M; Siegrist, Karen; Brown, Andrea M; Thomas, Michael E; Boggs, Nathan; Carter, Christopher C

    2012-04-20

    To develop a deeper understanding of the optical signatures of both biological aerosols and potential interferents, we made field measurements of optical cross sections and compared them to model-based predictions. We measured aerosol cross sections by conducting a hard-target calibration of a light detection and ranging system (LIDAR) based on the Frequency Agile Laser (FAL). The elastic backscatter cross sections are estimated at 19 long-wave infrared (LWIR) wavelengths spanning the range from 9.23 to 10.696 μm. The theoretical modeling of the elastic backscatter cross sections is based on the measured refractive index and size distribution of the aerosols, which are used as inputs into Mie calculations. Both model calculations and experimental measurements show good agreement and also indicate the presence of spectral features based on single particle absorption in the backscatter cross sections that can be used as a basis for discrimination for both standoff and point sensors.

  8. Measurement of backscatter factor for diagnostic radiology: methodology and uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, P.H.G.; Nogueira, M.D.S.; Squair, P.L.; Da Silva, T.A. [Centro de Desenvolvimento da Tecnoogia Nuclear (CDTN/CNEN) 30123-970, Minas Gerais (Brazil)]. e-mail: phgr@cdtn.br

    2007-07-01

    Full text: Backscatter factors were experimentally determined for the diagnostic X-ray qualities recommended by the International Electrotechnical Commission (IEC) for primary beams (RQR). Harshaw LiF-1 100H thermoluminescent dosemeters used for determining the backscatter were calibrated against an ionization chamber traceable to the National Metrology Laboratory. A 300mm x 300mm x 150mm PMMA slab phantom was used for deep-doses measurements. To perform the in-phantom measurements, the dosemeters were placed in the central axis of the x-ray beam at five different depths d in the phantom (5, 10, 15, 25 and 35 mm) upstream the beam direction. The typical combined standard uncertainty of the backscatter factor value was 6%. The main sources of uncertainties were the calibration procedure, the TLD dosimetry and the use of deep-dose curves. (Author)

  9. Bruce Thompson: Adventures and advances in ultrasonic backscatter

    Science.gov (United States)

    Margetan, Frank J.

    2012-05-01

    Over the course of his professional career Dr. R. Bruce Thompson published several hundred articles on non-destructive evaluation, the majority dealing with topics in ultrasonics. One longtime research interest of Dr. Thompson, with applications both to microstructure characterization and defect detection, was backscattered grain noise in metals. Over a 20 year period he led a revolving team of staff members and graduate students investigating various aspects of ultrasonic backscatter. As a member of that team I had the privilege of working along side Dr. Thompson for many years, serving as a sort of Dr. Watson to Bruce's Sherlock Holmes. This article discusses Dr. Thompson's general approaches to modeling backscatter, the research topics he chose to explore to systematically elucidate a better understanding of the phenomena, and the many contributions to the field achieved under his leadership. The backscatter work began in earnest around 1990, motivated by a need to improve inspections of aircraft engine components. At that time Dr. Thompson launched two research efforts. The first led to the heuristic Independent Scatterer Model which could be used to estimate the average grain noise level that would be seen in any given ultrasonic inspection. There the contribution from the microstructure was contained in a measureable parameter known as the Figure-of-Merit or FOM. The second research effort, spearheaded by Dr. Jim Rose, led to a formal relationship between FOM and details of the metal microstructure. The combination of the Independent Scattering Model and Rose's formalism provided a powerful tool for investigating backscatter in metals. In this article model developments are briefly reviewed and several illustrative applications are discussed. These include: the determination of grain size and shape from ultrasonic backscatter; grain noise variability in engine-titanium billets and forgings; and the design of ultrasonic inspection systems to improve defect

  10. Recovering an electromagnetic obstacle by a few phaseless backscattering measurements

    Science.gov (United States)

    Li, Jingzhi; Liu, Hongyu; Wang, Yuliang

    2017-03-01

    We consider the electromagnetic scattering from a convex polyhedral PEC or PMC obstacle due to a time-harmonic incident plane wave. It is shown that the modulus of the far-field pattern in the backscattering aperture possesses a certain local maximum behavior. Using the local maximum indicating phenomena, one can determine the exterior unit normal directions, as well as the face areas, of the front faces of the obstacle. Then we propose a recovery scheme of reconstructing the obstacle by phaseless backscattering measurements. This work significantly extends our recent study in Li and Liu (2014 preprint) from two dimensions and acoustic scattering to the more challenging three dimensions and electromagnetic scattering.

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

    Directory of Open Access Journals (Sweden)

    M. S. Twardowski

    2007-07-01

    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 scattering by pure seawater at their respective wavelengths. From a methodological perspective, there were several results:

    bbp 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

  12. 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

  13. Influence of Contractility on Myocardial Ultrasonic Integrated Backscatter and Cyclic Variation in Integrated Backscatter

    Institute of Scientific and Technical Information of China (English)

    毕小军; 邓又斌; 潘敏; 杨好意; 向慧娟; 常青; 黎春雷

    2002-01-01

    Summary: To evaluate the effects of left ventricular contractility on the changes of average image intensity (AII) of the myocardial integrated backscatter (IB) and cyclic variation in IB (CVIB), 7 adult mongrel dogs were studied. The magnitude of AII and CVIB were measured from myocardial IB carves before and after dobutamine or propranolol infusion. Dobutamine or propranolol did not affect the magnitude of AII (13.8±0. 7 vs 14.7±0. 5, P>0. 05 or 14.3±0.5 vs 14.2±0. 4, P>0. 05). However, dobutamine produced a significant increase in the magnitude of CVIB (6.8±0.3 vs 9.5 ± 0. 6, P<0. 001) and propranolol induced significant decrease in the magnitude of CVIB (7.1±0. 2 vs 5.2±0. 3, P<0. 001). The changes of the magnitude of AII and CVIB in the myocardium have been demonstrated to reflect different myocardial physiological and pathological changes respectively. The alteration of contractility did not affect the magnitude of AII but induced significant change in CVIB. The increase of left ventricular contractility resulted in a significant rise of the magnitude of CVIB and the decrease of left ventricular contractility resulted in a significant fall of the magnitude of CVIB.

  14. On the maximum backscattering cross section of passive linear arrays

    DEFF Research Database (Denmark)

    Solymar, L.; Appel-Hansen, Jørgen

    1974-01-01

    The maximum backscattering cross section of an equispaced linear array connected to a reactive network and consisting of isotropic radiators is calculated forn = 2, 3, and 4 elements as a function of the incident angle and of the distance between the elements. On the basis of the results obtained...

  15. Backscatter B [USGS]--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...

  16. 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 tex

  17. Radar Backscatter Across the Gulf Stream Sea Surface Temperature Front

    Science.gov (United States)

    Nghiem, S. V.; Li, F. K.; Walsh, E. J.; Lou, S. H.

    1998-01-01

    Ocean backscatter signatures were measured by the Jet Propulsion Laboratory airborne NUSCAT K(sub u)-band scatterometer across the Gulf Stream sea surface temperature front. The measurements were made during the Surface Wave Dynamics Experiment (SWADE) off the coast of Virginia and Maryland in the winter of 1991.

  18. 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...

  19. 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...

  20. Using Back-Scattering to Enhance Efficiency in Neutron Detectors

    CERN Document Server

    Kittelmann, Thomas; Cai, Xiao Xiao; Kanaki, Kalliopi; Cooper-Jensen, Carsten P; Hall-Wilton, Richard

    2015-01-01

    The principle of using strongly scattering materials to recover efficiency in neutron detectors, via back-scattering of unconverted thermal neutrons, is discussed in general. Feasibility of the method is illustrated through Geant4-based simulations of a specific setup involving a moderator-like material placed behind a single layered boron-10 thin film gaseous detector.

  1. 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...

  2. Transport properties and superconductivity in presence of backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Mattis, D. (Utah Univ., Salt Lake City, UT (United States). Dept. of Physics); Rudin, S. (Army Electronics Technology and Devices Lab., Fort Monmouth, NJ (United States))

    1992-04-20

    In this paper, the authors achieve an exact evaluation of the Kubo formula for electrical resistivity, with a model in which random impurity scattering is parametrized by random back-scattering matrix elements. If the alloy is a superconductor, our theory allows us to correlate T{sub c} with the normal-phase resistivity. The results are in nice agreement with experiment.

  3. Backscatter A [CSUMB]--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 of Ventura map area, California. The raster data...

  4. Simulation of multistatic and backscattering cross sections for airborne radar

    Science.gov (United States)

    Biggs, Albert W.

    1986-07-01

    In order to determine susceptibilities of airborne radar to electronic countermeasures and electronic counter-countermeasures simulations of multistatic and backscattering cross sections were developed as digital modules in the form of algorithms. Cross section algorithms are described for prolate (cigar shape) and oblate (disk shape) spheroids. Backscattering cross section algorithms are also described for different categories of terrain. Backscattering cross section computer programs were written for terrain categorized as vegetation, sea ice, glacial ice, geological (rocks, sand, hills, etc.), oceans, man-made structures, and water bodies. PROGRAM SIGTERRA is a file for backscattering cross section modules of terrain (TERRA) such as vegetation (AGCROP), oceans (OCEAN), Arctic sea ice (SEAICE), glacial snow (GLASNO), geological structures (GEOL), man-made structures (MAMMAD), or water bodies (WATER). AGCROP describes agricultural crops, trees or forests, prairies or grassland, and shrubs or bush cover. OCEAN has the SLAR or SAR looking downwind, upwind, and crosswind at the ocean surface. SEAICE looks at winter ice and old or polar ice. GLASNO is divided into a glacial ice and snow or snowfields. MANMAD includes buildings, houses, roads, railroad tracks, airfields and hangars, telephone and power lines, barges, trucks, trains, and automobiles. WATER has lakes, rivers, canals, and swamps. PROGRAM SIGAIR is a similar file for airborne targets such as prolate and oblate spheroids.

  5. 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 und

  6. 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...

  7. 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...

  8. BackscatterC [7125]--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...

  9. 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...

  10. 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...

  11. BackscatterB [Swath]--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...

  12. 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.

  13. 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...

  14. 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...

  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. A comparative study of RADAR Ka-band backscatter

    Science.gov (United States)

    Mapelli, D.; Pierdicca, N.; Guerriero, L.; Ferrazzoli, Paolo; Calleja, Eduardo; Rommen, B.; Giudici, D.; Monti Guarnieri, A.

    2014-10-01

    Ka-band RADAR frequency range has not yet been used for Synthetic Aperture Radar (SAR) from space so far, although this technology may lead to important applications for the next generation of SAR space sensors. Therefore, feasibility studies regarding a Ka-band SAR instrument have been started [1][2], for the next generation of SAR space sensors. In spite of this, the lack of trusted references on backscatter at Ka-band revealed to be the main limitation for the investigation of the potentialities of this technology. In the framework of the ESA project "Ka-band SAR backscatter analysis in support of future applications", this paper is aimed at the study of wave interaction at Ka-band for a wide range of targets in order to define a set of well calibrated and reliable Ka-band backscatter coefficients for different kinds of targets. We propose several examples of backscatter data resulting from a critical survey of available datasets at Ka-band, focusing on the most interesting cases and addressing both correspondences and differences. The reliability of the results will be assessed via a preliminary comparison with ElectroMagnetic (EM) theoretical models. Furthermore, in support of future technological applications, we have designed a prototypal software acting as a "library" of earth surface radar response. In our intention, the output of the study shall contribute to answer to the need of a trustworthy Ka-Band backscatter reference. It will be of great value for future technological applications, such as support to instrument analysis, design and requirements' definition (e.g.: Signal to Noise Ratio, Noise Equivalent Sigma Zero).

  17. 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

  18. 3D Visualization of Radar Backscattering Diagrams Based on OpenGL

    Science.gov (United States)

    Zhulina, Yulia V.

    2004-12-01

    A digital method of calculating the radar backscattering diagrams is presented. The method uses a digital model of an arbitrary scattering object in the 3D graphics package "OpenGL" and calculates the backscattered signal in the physical optics approximation. The backscattering diagram is constructed by means of rotating the object model around the radar-target line.

  19. 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.

  20. 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.

  1. Electron backscatter diffraction of a plutonium-gallium alloy

    Science.gov (United States)

    Boehlert, C. J.; Zocco, T. G.; Schulze, R. K.; Mitchell, J. N.; Pereyra, R. A.

    2003-01-01

    An experimental technique has recently been developed to characterize reactive metals, including plutonium (Pu) and cerium, using electron backscatter diffraction (EBSD). Microstructural characterization of Pu and its alloys by EBSD had been previously elusive primarily because of the extreme toxicity and rapid surface oxidation rate associated with Pu metal. The experimental technique, which included ion-sputtering the metal surface using a scanning Auger microprobe (SAM) followed by vacuum transfer of the sample from the SAM to the scanning electron microscope (SEM), used to obtain electron backscatter diffraction Kikuchi patterns and orientation maps for a Pu-gallium alloy is described and the initial microstructural observations based on the analysis are discussed. The phase transformation behavior between the δ (face-centered cubic) and ɛ (body-centered-cubic) structures is explained by combining the SEM and EBSD observations.

  2. Control of coherent backscattering by breaking optical reciprocity

    CERN Document Server

    Bromberg, Y; Popoff, S M; Cao, H

    2015-01-01

    Reciprocity is a universal principle that has a profound impact on many areas of physics. A fundamental phenomenon in condensed-matter physics, optical physics and acoustics, arising from reciprocity, is the constructive interference of quantum or classical waves which propagate along time-reversed paths in disordered media, leading to, for example, weak localization and metal-insulator transition. Previous studies have shown that such coherent effects are suppressed when reciprocity is broken. Here we show that by breaking reciprocity in a controlled manner, we can tune, rather than simply suppress, these phenomena. In particular, we manipulate coherent backscattering of light, also known as weak localization. By utilizing a non-reciprocal magneto-optical effect, we control the interference between time-reversed paths inside a multimode fiber with strong mode mixing, and realize a continuous transition from the well-known peak to a dip in the backscattered intensity. Our results may open new possibilities fo...

  3. 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.

  4. Theoretical Analysis of Rayleigh Backscattering Noise in Fiber Raman Amplifiers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In this paper, a new theoretical model for Rayleigh backscattering (RB) analysis of fiber Raman amplifiers is proposed. The model includes all the interactions among the pumps, signals, and all orders of RB. The results show that the higher order RB has a negligible influence on the performance of the amplifier. The co-propagating and counterpropagating RB power of the signal grow quadratically with the net-gain of the amplifier. The signal to double Rayleigh backscattering noise ratio (OSNRDRB ) of backward-pumped FRAs is better than that of the forward-pumped ones at high net-gain level (> 13 dB), while at low net-gain level the OSNRDrb of the forward-pumped FRAs is slightly better than that of the backward-pumped ones.

  5. 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.

  6. Coherent inelastic backscattering of laser light from three isotropic atoms

    CERN Document Server

    Ketterer, Andreas; Shatokhin, Vyacheslav N

    2014-01-01

    We study the impact of double and triple scattering contributions on coherent backscattering of laser light from saturated isotropic atoms, in the helicity preserving polarization channel. Using the recently proposed diagrammatic pump-probe approach, we analytically derive single-atom spectral responses to a classical polychromatic driving field, combine them self-consistently to double and triple scattering processes, and numerically deduce the corresponding elastic and inelastic spectra, as well as the total backscattered intensities. We find that account of the triple scattering contribution leads to a faster decay of phase-coherence with increasing saturation of the atomic transition as compared to double scattering alone, and to a better agreement with the experiment on strontium atoms.

  7. Reduced Brillouin backscatter in CO2 laser-target interaction

    Science.gov (United States)

    Ng, A.; Offenberger, A. A.; Karttunen, S. J.

    1981-02-01

    A substantially reduced Brillouin reflection has been found for CO2 laser-irradiated high-density gas targets. In contrast to the high reflectivity (60%) previously observed for underdense hydrogen plasma, total backscatter (stimulated plus specular) is found to peak at 30% for incident intensity 5 times 10 to the twelfth W per square centimeter and decrease thereafter to 18% at 10 to the thirteenth W per square centimeter. The ponderomotive effects are postulated to account for these observations.

  8. Pattern matching approach to pseudosymmetry problems in electron backscatter diffraction.

    Science.gov (United States)

    Nolze, Gert; Winkelmann, Aimo; Boyle, Alan P

    2016-01-01

    We demonstrate an approach to overcome Kikuchi pattern misindexing problems caused by crystallographic pseudosymmetry in electron backscatter diffraction (EBSD) measurements. Based on the quantitative comparison of experimentally measured Kikuchi patterns with dynamical electron diffraction simulations, the algorithm identifies the best-fit orientation from a set of pseudosymmetric candidates. Using measurements on framboidal pyrite (FeS2) as an example, we also show the improvement of the orientation precision using this approach.

  9. Surface effects on the microwave backscatter and emission of snow

    Science.gov (United States)

    Fung, A. K.; Stiles, W. H.; Ulaby, F. T.

    1980-01-01

    Measurements were performed with active and passive microwave sensors for both dry and wet snow conditions. A layer of Rayleigh scatterers with irregular surface boundaries is found to be a reasonable model for interpreting passive and active measurements in X- and Ku-bands. It was found that roughness had a significant effect on both backscatter and emission from wet snow; however, only a small effect was noted for dry snow.

  10. Observation of transverse coherent backscattering in disordered photonic structures

    CERN Document Server

    Brake, Sebastian; Leykam, Daniel; Desyatnikov, Anton; Denz, Cornelia

    2015-01-01

    We report on the experimental observation of weak localization in an optically induced disordered (2+1)-dimensional photonic structure. Our flexible method of optical induction is applied with a nondiffracting random intensity distribution. We focus on the analysis of a statistical output spectrum for many probe events with variance of the incoming beam's transverse spatial frequency. For particular spatial frequencies we find considerable signatures of transverse coherent backscattering.

  11. Valley-protected backscattering suppression in silicon photonic graphene

    CERN Document Server

    Chen, Xiao-Dong

    2016-01-01

    In this paper, we study valley degree of freedom in all dielectric silicon photonic graphene. Photonic band gap opening physics under inversion symmetry breaking is revisited by the viewpoint of nonzero valley Chern number. Bulk valley modes with opposite orbital angular momentum are unveiled by inspecting time-varying electric fields. Topological transition is well illustrated through photonic Dirac Hamiltonian. Valley dependent edge states and the associated valley-protected backscattering suppression around Z-shape bend waveguide have been demonstrated.

  12. Simulation Studies of the Backscattering Signal in HSRL Technique

    CERN Document Server

    Georgakopoulou, Angelika

    2012-01-01

    The technique of High Spectral Resolution Lidar (HSRL) for atmospheric monitoring allows the determination of the aerosol to molecular ratio and can be used in UHECR Observatories using air fluorescence telescopes. By this technique a more accurate estimate of the Cherenkov radiation superimposed to the fluorescence signal can be achieved. A laboratory setup was developed to determine the backscattering coefficients using microparticles diluted in water and diffusion interfaces. In this setup we used a CW SLM laser at 532 nm and a 250 mm Newtonian telescope. Simulations of the above experimental configuration have been made using Scatlab\\c{opyright}, FINESSE\\c{opyright} 0.99.8 and MATLAB\\c{opyright} and are presented in this work. We compare the simulated 2-dimensional Fabry-Perot fringe images of the backscattering signal recorded in the CCD sensor with that of experimental ones. Additionally, we simulated the backscattering of the laser beam by the atmosphere at a height of 2000 m and we have studied the in...

  13. Investigation of phonon coherence and backscattering using silicon nanomeshes

    Science.gov (United States)

    Lee, Jaeho; Lee, Woochul; Wehmeyer, Geoff; Dhuey, Scott; Olynick, Deirdre L.; Cabrini, Stefano; Dames, Chris; Urban, Jeffrey J.; Yang, Peidong

    2017-01-01

    Phonons can display both wave-like and particle-like behaviour during thermal transport. While thermal transport in silicon nanomeshes has been previously interpreted by phonon wave effects due to interference with periodic structures, as well as phonon particle effects including backscattering, the dominant mechanism responsible for thermal conductivity reductions below classical predictions still remains unclear. Here we isolate the wave-related coherence effects by comparing periodic and aperiodic nanomeshes, and quantify the backscattering effect by comparing variable-pitch nanomeshes. We measure identical (within 6% uncertainty) thermal conductivities for periodic and aperiodic nanomeshes of the same average pitch, and reduced thermal conductivities for nanomeshes with smaller pitches. Ray tracing simulations support the measurement results. We conclude phonon coherence is unimportant for thermal transport in silicon nanomeshes with periodicities of 100 nm and higher and temperatures above 14 K, and phonon backscattering, as manifested in the classical size effect, is responsible for the thermal conductivity reduction. PMID:28051081

  14. Backscatter LIDAR signal simulation applied to spacecraft LIDAR instrument design

    Science.gov (United States)

    Fochesatto, J.; Ristori, P.; Flamant, P.; Machado, M. E.; Singh, U.; Quel, E.

    2004-01-01

    In the framework of the scientific cooperation between the CEILAP laboratory (Argentina) and IPSL Institut Pierre Simon Laplace (France), devoted to the development of LIDAR techniques for Atmospheric sciences, a new area of scientific research, involving LIDARs, is starting in Argentine space technology. This new research area is under consideration at CEILAP in a joint effort with CONAE, the Argentine space agency, responsible for the development of future space missions. The LIDAR technique is necessary to improve our knowledge of meteorological, dynamic, and radiative processes in the South American region, for the whole troposphere and the lower stratosphere. To study this future mission, a simple model for the prediction of backscatter LIDAR signal from a spacecraft platform has been used to determine dimensions and detection characteristics of the space borne LIDAR instrument. The backscatter signal was retrieved from a modeled atmosphere considering its molecular density profile and taking into account different aerosols and clouds conditions. Signal-to-noise consideration, within the interval of possible dimension of the instrument parameters, allows us to constrain the telescope receiving area and to derive maximum range achievable, integration time and the final spatial and temporal resolutions of backscatter profiles.

  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.

    ) to (bm4) (Figure: a). The backscatter levels of the buried mounds are comparable with the backscatter level obtained from the mounds. Bathymetry wise a pronounced depression is observed south of the mound province having very high backscatter.... The presence of strong backscatter (-30dB) at the slope in the topographically depressed area indirectly attests the presence of active seafloor current which may be guiding coarse material towards the depressions. Two parallel low backscatter bands showing...

  16. Coherent Backscatter Opposition Effect from Scratches on Solid Surfaces

    Science.gov (United States)

    Hapke, B. W.; Piatek, J. L.; Nelson, R. M.; Smythe, W. D.; Hale, A. S.

    2003-05-01

    Shepard and Arvidson [1] discovered that the solid surfaces of rocks exhibit an opposition effect. We have measured the phase curve of a natural surface of a piece of solid basalt between 0.05 and 5 degrees in circularly polarized light using the JPL long arm goniometer and confirmed that it has an opposition effect. The circular polarization ratio (CPR) increased with decreasing phase angle, consistent with a coherent backscatter opposition effect (CBOE) Recent laboratory investigations of the CBOE in planetary regolith analogs [2,3,4] have revealed that the width of the peak is remarkably insensitive to particle size, in strong contrast to theoretical expectations. We have hypothesized that one of the reasons for this might be that multiple scattering between irregularities, such as scratches, on the surfaces of a particle could cause coherent backscatter, in addition to scattering between particles. To test this hypothesis we ground the surface of a piece of plate glass with 5 micrometer abrasive and measured its phase curve. As the phase angle decreases, the intensity increases and the CPR decreases, consistent with specular reflection. However, near zero phase there is a nonlinear rise about 2 degrees wide superimposed on the linear specular peak accompanied by an increase in CPR, showing that coherent backscatter is occuring. A piece of commercial diffusing glass exhibited the same phenomena. These results support our hypothesis and also provide a possible explanation for the observations of opposition effects from the solid surfaces of rocks. This research was supported by a grant from NASA's PGG Program References cited: [1] Shepard and Arvidson, Icarus, 141, 172-178 (1999). [2] Nelson et al, Icarus, 147, 545-558 (2000). [3] Nelson et al, Planet. Space Sci., 50, 849-856 (2002). [4] Piatek et al, Abstract, DPS Conference (2003).

  17. Concentration measurement of yeast suspensions using high frequency ultrasound backscattering.

    Science.gov (United States)

    Elvira, Luis; Vera, Pedro; Cañadas, Francisco Jesús; Shukla, Shiva Kant; Montero, Francisco

    2016-01-01

    This work proposes the use of an ultrasound based technique to measure the concentration of yeasts in liquid suspension. This measurement was achieved by the detection and quantification of ultrasonic echoes backscattered by the cells. More specifically, the technique was applied to the detection and quantification of Saccharomyces cerevisiae. A theoretical approach was proposed to get the average density and sound speed of the yeasts, which were found to be 1116 kg/m(3) and 1679 m/s, respectively. These parameters were needed to model the waves backscattered by each single cell. A pulse-echo arrangement working around 50 MHz, being able to detect echoes from single yeasts was used to characterize experimentally yeast solutions from 10(2) to 10(7)cells/ml. The Non-negative Matrix Factorization denoising technique was applied for data analysis. This technique required a previous learning of the spectral patterns of the echoes reflected from yeasts in solution and the base noise from the liquid medium. Comparison between pulse correlation (without denoising) and theoretical and experimental pattern learning was made to select the best signal processing. A linear relation between ultrasound output and concentration was obtained with correlation coefficient R(2)=0.996 for the experimental learning. Concentrations from 10(4) to 10(7)cells/ml were detected above the base noise. These results show the viability of using the ultrasound backscattering technique to detect yeasts and measure their concentration in liquid cultures, improving the sensitivity obtained using spectrophotometric methods by one order of magnitude.

  18. 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.

  19. 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...this to mean that the plume head and "neck" are defined by the 40-dB contour and that the eastward tilt is part of the bottomside back- scatter region...plume approaches its maximum height. We define this time of altitude stagnation in plume growth as the end of the growth phase and the beginning of the

  20. High resolution backscattering studies of nanostructured magnetic and semiconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, A. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal)]. E-mail: afonseca@itn.pt; Franco, N. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Alves, E. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Barradas, N.P. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Leitao, J.P. [Departamento de Fisica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Sobolev, N.A. [Departamento de Fisica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Banhart, D.F. [Z. E. Elektronenmikroskopie, Universitaet Ulm, Albert-Einstein-Allee 11, D-89069 Ulm (Germany); Presting, H. [Daimler-Chrysler Forschungszentrum, 89081 Ulm (Germany); Ulyanov, V.V. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation); Nikiforov, A.I. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation)

    2005-12-15

    Low dimension structures raises inevitably new technological challenges in materials science. The new structures must fulfill stringent requirements in composition, crystalline quality and interface sharpness among others. We present and discuss the results of Si/Ge quantum structures and FePt/C multilayer structures deposited at different temperatures by ion beam sputtering. Evidence for the presence of FePt nanoparticles embedded in the C matrix and Ge islands in Ge/Si multilayers structures was found. Size and stoichiometry of the nanoparticles and the multilayer periodicity was obtained using Rutherford backscattering at grazing angles of incidence. The strain state of the single crystalline layers was determined by tilt axis channelling.

  1. DUNBID, the Delft University neutron backscattering imaging detector

    Energy Technology Data Exchange (ETDEWEB)

    Bom, V.R. [Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail: vb@iri.tudelft.nl; Eijk, C.W.E. van [Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Ali, M.A. [Atomic Energy Authority, Nuclear Research Center, Reactor and Neutron Physics Department, P.O. Box 13759, Abu Zabal, Cairo (Egypt)

    2005-12-01

    In the search for low-metallic land mines, the neutron backscattering technique may be applied if the soil is sufficiently dry. An advantage of this method is the speed of detection: the scanning speed may be made comparable to that of a metal detector. A two-dimensional position sensitive detector is tested to obtain an image of the back scattered thermal neutron radiation. Results of experiments using a radionuclide neutron source are presented. The on-mine to no-mine signal ratio can be improved by the application of a window on the neutron time-of-flight. Results using a pulsed neutron generator are also presented.

  2. 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)

  3. Combined backscatter and transmission method for nuclear density gauge

    Directory of Open Access Journals (Sweden)

    Golgoun Seyed Mohammad

    2015-01-01

    Full Text Available Nowadays, the use of nuclear density gauges, due to the ability to work in harsh industrial environments, is very common. In this study, to reduce error related to the ρ of continuous measuring density, the combination of backscatter and transmission are used simultaneously. For this reason, a 137Cs source for Compton scattering dominance and two detectors are simulated by MCNP4C code for measuring the density of 3 materials. Important advantages of this combined radiometric gauge are diminished influence of μ and therefore improving linear regression.

  4. HAB detection based on absorption and backscattering properties of phytoplankton

    Science.gov (United States)

    Lei, Hui; Pan, Delu; Bai, Yan; Chen, Xiaoyan; Zhou, Yan; Zhu, Qiankun

    2011-11-01

    The coastal area of East China Sea (ECS) suffers from the harmful algal blooms (HAB) frequently every year in the warm season. The most common causative phytoplankton algal species of HAB in the ECS in recent years are Prorocentrum donghaiense (dinoflagellates), Karenia mikimotoi (dinoflagellates which could produce hemolytic and ichthyotoxins) and Skeletonema costatum (diatom). The discrimination between the dinoflagellates and diatom HAB through ocean color remote sensing approach can add the knowledge of HAB events in ECS and help to the precaution. A series of in-situ measurement consisted of absorption coefficient, total scattering and particulate backscattering coefficient was conducted in the southern coast of Zhejiang Province in May 2009, and the estuary of Changjiang River in August 2009 and December 2010, which encountered two HAB events and a moderate bloom. The Inherent Optical Properties (IOPs) of the bloom waters have significant difference between phytoplankton species in absorption and backscattering properties. The chlorophyll a specific absorption coefficient (a*phy(λ)) for the bloom patches (chlorophyll a concentration >6mg m-3) differ greatly from the adjacent normal seawater, with the a*phy(λ) of bloom water lower than 0.03 m2 mg-1 while the a*phy(λ) of the adjacent normal seawater is much higher (even up to 0.06 m2 mg-1). Meanwhile, the backscattering coefficients at 6 wavebands (420, 442, 470, 510, 590 and 700nm) are also remarkably lower for bloom waters ( 0.02 m-1). The backscattering coefficient ratio (Rbp(λ)) is much lower for diatom bloom waters than for dinoflagellates types (0.01079 vs. 0.01227). A discrimination model based on IOPs is established, and several typical dinoflagellates and diatom bloom events including Prorocentrum donghaiense, Karenia mikimotoi and Skeletonema costatum in the ECS are picked out for testing with the MODIS-L2 and L3 ocean color remote sensing products from NASA website. The result proves that the

  5. 3D Visualization of Radar Backscattering Diagrams Based on OpenGL

    Directory of Open Access Journals (Sweden)

    Yulia V. Zhulina

    2004-03-01

    Full Text Available A digital method of calculating the radar backscattering diagrams is presented. The method uses a digital model of an arbitrary scattering object in the 3D graphics package “OpenGL” and calculates the backscattered signal in the physical optics approximation. The backscattering diagram is constructed by means of rotating the object model around the radar-target line.

  6. Monte Carlo Simulation of the Coaxial Electrons Backscattering from Thin Films

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using the Monte Carlo method, we simulated the trajectories of coaxial backscattering electrons corresponding to a new type of scanning electron microscope. From the calculated results, we obtain a universal expression, which describes with good accuracy the backscattering coefficient versus film thickness under all conditions used. By measuring the coaxial backscattering coefficient and using this universal formula, the thickness of thin films can be determined if the composition is known.

  7. Electron energy loss and diffraction of backscattered electrons from silicon

    Science.gov (United States)

    Winkelmann, Aimo; Aizel, Koceila; Vos, Maarten

    2010-05-01

    Electrons backscattered from crystals can show Kikuchi patterns: variations in intensity for different outgoing directions due to diffraction by the lattice. Here, we measure these effects as a function of their energy loss for 30 keV electrons backscattered from silicon. The change in diffraction contrast with energy loss depends strongly on the scattering geometry. At steep incidence on the sample, diffraction contrast in the observed Kikuchi bands decreases rapidly with energy loss. For an energy loss larger than about 150 eV the contrast is more than 5 times less than the contrast due to electrons near zero energy loss. However, for grazing incidence angles, maximum Kikuchi band contrast is observed for electrons with an energy loss near 60 eV, where the contrast is more than 2.5× larger than near zero energy loss. In addition, in this grazing incidence geometry, the Kikuchi diffraction effects stay significant even for electrons that have lost hundreds of electron volts. For the maximum measured energy loss of 440 eV, the electrons still show a contrast that is 1.5 × larger than that of the electrons near zero energy loss. These geometry-dependent observations of Kikuchi band diffraction contrast are interpreted based on the elastic and inelastic scattering properties of electrons and dynamical diffraction simulations.

  8. 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.)

  9. Discriminant classification of different fish-species backscattering

    Science.gov (United States)

    Zhang, Qiao; Xu, Feng; Liu, Yin; Zhang, Chun

    2012-11-01

    The complex structure of fish and multispecies composition complicate the analysis of acoustic data. Consequently, it is difficult to obtain a highly accurate rate of classification by using current approaches. This paper introduces two discriminating methods: the adaptive segmentation temporal centroid method and the wavelet packet multi-scale information entropy method. To verify and compare these two methods, an ex situ experiment has been performed with three kinds of fish: Crucian carp (Carassius auratus), Yellow-headed catfish (Pelteobagrus fulvidraco) and Bluntnose black bream (Megalobrama amblycephale). The backscattering signals of these fishes are obtained. Then the temporal centroid in the divided sub-segmentation of the backscattering envelope is calculated, and the multi-scale information entropy of the wavelet packet decomposition in different frequency bands is extracted. Finally, three kinds of fish are successfully classified by using a BP neural network. The result shows that the adaptive segmentation temporal centroid method is 4% more accurate than the wavelet packet multi-scale information entropy method.

  10. 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.)

  11. Study of sporadic-E clouds by backscatter radar

    Directory of Open Access Journals (Sweden)

    Z. Houminer

    Full Text Available It is shown that swept-frequency backscatter ionograms covering a range of azimuths can be used to study the dynamics of sporadic-E clouds. A simple technique based on analytic ray tracing can be used to simulate the observed narrow traces associated with Es patches. This enables the location and extent of the sporadic-E clouds to be determined. The motion of clouds can then be determined from a time sequence of records. In order to demonstrate the method, results are presented from an initial study of 5 days of backscatter ionograms from the Jindalee Stage B data base obtained during March-April 1990. Usually 2–3 clouds were observed each day, mainly during the evening and up to midnight. The clouds lasted from 1–4 h and extended between 30°–80° in azimuth and 150-800 km in range. The clouds were mostly stationary or drifted generally westward with velocities of up to 80 m s–1. Only one cloud was observed moving eastward.

  12. Dynamical electron backscatter diffraction patterns. Part I: pattern simulations.

    Science.gov (United States)

    Callahan, Patrick G; De Graef, Marc

    2013-10-01

    A new approach for the simulation of dynamic electron backscatter diffraction (EBSD) patterns is introduced. The computational approach merges deterministic dynamic electron-scattering computations based on Bloch waves with a stochastic Monte Carlo (MC) simulation of the energy, depth, and directional distributions of the backscattered electrons (BSEs). An efficient numerical scheme is introduced, based on a modified Lambert projection, for the computation of the scintillator electron count as a function of the position and orientation of the EBSD detector; the approach allows for the rapid computation of an individual EBSD pattern by bi-linear interpolation of a master EBSD pattern. The master pattern stores the BSE yield as a function of the electron exit direction and exit energy and is used along with weight factors extracted from the MC simulation to obtain energy-weighted simulated EBSD patterns. Example simulations for nickel yield realistic patterns and energy-dependent trends in pattern blurring versus filter window energies are in agreement with experimental energy-filtered EBSD observations reported in the literature.

  13. 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.

  14. 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)

  15. 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.

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

    Science.gov (United States)

    Bristow, William; Hysell, David

    2016-07-01

    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.

  17. 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...

  18. Subgrid-scale backscatter after the shock-turbulence interaction

    Science.gov (United States)

    Livescu, Daniel; Li, Zhaorui

    2017-01-01

    The statistics of the subgrid scales (SGS) are studied in the context of Large Eddy Simulations (LES) of turbulence after the interaction with a nominally normal shock wave. In general, in practical applications, the shock wave width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to resolve the shock wave, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number ≈ 180 are used for an analysis of the SGS backscatter properties. In particular, it is shown that the interaction with the shock wave decreases the asymmetry of the SGS dissipation Probability Density Function (PDF) as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter.

  19. Kinematics of Compton backscattering x-ray source for angiography

    Energy Technology Data Exchange (ETDEWEB)

    Blumberg, L.N.

    1992-05-01

    Calculations of X-Ray production rates, energy spread, and spectrum of Compton-backscattered photons from a Free Electron Laser on an electron beam in a low energy (136-MeV) compact (8.5-m circumference) storage ring indicate that an X-Ray intensity of 34.6 10{sup 7} X-Ray photons per 0.5-mm {times} 0.5-mm pixel for Coronary Angiography near the 33.169-keV iodine K-absorption edge can be achieved in a 4-msec pulse within a scattering cone of 1-mrad half angle. This intensity, at 10-m from the photon-electron interaction point to the patient is about a factor of 10 larger than presently achieved from a 4.5-T superconducting wiggler source in the NSLS 2.5-GeV storage ring and over an area about 5 times larger. The 2.2-keV energy spread of the Compton-backscattered beam is, however, much larger than the 70-eV spread presently attained form the wiggler source and use of a monochromator. The beam spot at the 10-m interaction point-to-patient distance is 20-mm diameter; larger spots are attainable at larger distances but with a corresponding reduction in X-Ray flux. Such a facility could be an inexpensive clinical alternative to present methods of non-invasive Digital Subtraction Angiography (DSA), small enough to be deployed in an urban medical center, and could have other medical, industrial and aerospace applications. Problems with the Compton backscattering source include laser beam heating of the mirror in the FEL oscillator optical cavity, achieving a large enough X-Ray beam spot at the patient, and obtaining radiation damping of the transverse oscillations and longitudinal emittance dilution of the storage ring electron beam resulting from photon-electron collisions without going to higher electron energy where the X-Ray energy spread becomes excessive for DSA. 38 refs.

  20. 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 10x10-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 30

  1. 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 3

  2. Identification of major backscattering sources in trees and shrubs at 10 GHz

    Science.gov (United States)

    Zoughi, R.; Wu, L. K.; Moore, R. K.

    1986-01-01

    A short-range very-fine-resolution FM-CW radar scatterometer has been used to identify the primary contributors to 10-GHz radar backscatter from pine, pin oak, American sycamore and sugar maple trees, and from creeping juniper shrubs. This system provided a range resolution of 11 cm and gave a 16-cm diameter illumination area at the target range of about 4 m. For a pine tree, the needles caused the strongest backscatter as well as the strongest attenuation in the radar signal. Cones, although insignificant contributors to the total backscatter, were more important for backscattering than for attenuation. For the rest of the trees, leaves were the strongest cause of backscattering and attenuation. However, in the absence of leaves, the petioles, small twigs, and branches gave relatively strong backscatter. For American sycamore and sugar maple trees, the fruits did not affect the total backscatter unless they were packed in clusters. For creeping juniper the backscattered energy and attenuation in the radar signal were mainly due to the top two layers of the evergreen scales. The contribution of the tree trunks was not determined.

  3. Simulation-guided optimization of small-angle analyzer geometry in the neutron backscattering spectrometer SPHERES.

    Science.gov (United States)

    Wuttke, Joachim; Zamponi, Michaela

    2013-11-01

    The resolution of neutron backscattering spectrometers deteriorates at small scattering angles where analyzers deviate from exact backscattering. By reducing the azimuth angle range of the analyzers, the resolution can be improved with little loss of peak intensity. Measurements at the spectrometer SPHERES are in excellent agreement with simulations, which proves the dominance of geometric effects.

  4. Simulation-guided optimization of small-angle analyzer geometry in the neutron backscattering spectrometer SPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Wuttke, Joachim; Zamponi, Michaela [Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany)

    2013-11-15

    The resolution of neutron backscattering spectrometers deteriorates at small scattering angles where analyzers deviate from exact backscattering. By reducing the azimuth angle range of the analyzers, the resolution can be improved with little loss of peak intensity. Measurements at the spectrometer SPHERES are in excellent agreement with simulations, which proves the dominance of geometric effects.

  5. Using multi-beam echo sounder backscatter data for sediment classification in very shallow water environments

    NARCIS (Netherlands)

    Amiri-Simkooei, A.R.; Snellen, M.; Simons, D.G.

    2009-01-01

    In a recent work described in Ref. [1], an angle-independent methodology was developed to use the multi-beam echo sounder backscatter (MBES) data for the seabed sediment classification. The method employs the backscatter data at a certain angle to obtain the number of sediment classes and to discrim

  6. Combining angular response classification and backscatter imagery segmentation for benthic biological habitat mapping

    Science.gov (United States)

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

    2012-01-01

    Backscatter information from multibeam echosounders (MBES) have been shown to contain useful information for the characterisation of benthic habitats. Compared to backscatter imagery, angular response of backscatter has shown advantages for feature discrimination. However its low spatial resolution inhibits the generation of fine scale habitat maps. In this study, angular backscatter response was combined with image segmentation of backscatter imagery to characterise benthic biological habitats in Discovery Bay Marine National Park, Victoria, Australia. Angular response of backscatter data from a Reson Seabat 8101 MBES (240 kHz) was integrated with georeferenced underwater video observations for constructing training data. To produce benthic habitat maps, decision tree supervised classification results were combined with mean shift image segmentation for class assignment. The results from mean angular response characteristics show effects of incidence angle at the outer angle for invertebrates (INV) and mixed red and invertebrates (MRI) classes, whilst mixed brown algae (MB) and mixed brown algae and invertebrates (MBI) showed similar responses independent from incidence angle. Automatic segmentation processing produce over segmented results but showed good discrimination between heterogeneous regions. Accuracy assessment from habitat maps produced overall accuracies of 79.6% (Kappa coefficient = 0.66) and 80.2% (Kappa coefficient = 0.67) for biota and substratum classifications respectively. MRI and MBI produced the lowest average accuracy while INV the highest. The ability to combine angular response and backscatter imagery provides an alternative approach for investigating biological information from acoustic backscatter data.

  7. Effect of the cortex on ultrasonic backscatter measurements of cancellous bone

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmeister, Brent K; Holt, Andrew P [Department of Physics, Rhodes College, Memphis, TN (United States); Kaste, Sue C, E-mail: hoffmeister@rhodes.edu [Department of Diagnostic Imaging, St Jude Children' s Research Hospital, Memphis, TN (United States)

    2011-10-07

    Ultrasonic backscatter techniques offer a promising new approach for detecting changes in bone caused by osteoporosis. However, several challenges impede clinical implementation of backscatter techniques. This study examines how the dense outer surface of bone (the cortex) affects backscatter measurements of interior regions of porous (cancellous) bone tissue. Fifty-two specimens of bone were prepared from 13 human femoral heads so that the same region of cancellous bone could be ultrasonically interrogated through the cortex or along directions that avoided the cortex. Backscatter signals were analyzed over a frequency range of 0.8-3.0 MHz to determine two ultrasonic parameters: apparent integrated backscatter (AIB) and frequency slope of apparent backscatter (FSAB). The term 'apparent' means that the parameters are sensitive to the frequency-dependent effects of diffraction and attenuation. Significant (p < 0.001) changes in AIB and FSAB indicated that measurements through the cortex decreased the apparent backscattered power and increased the frequency dependence of the power. However, the cortex did not affect the correlation of AIB and FSAB with the x-ray bone mineral density of the specimens. This suggests that results from many previous in vitro backscatter studies of specimens of purely cancellous bone may be extrapolated with greater confidence to in vivo conditions.

  8. Morphology of pockmarks along the western continental margin of India: Employing multibeam bathymetry and backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Dandapath, S.; Chakraborty, B.; Karisiddaiah, S.M.; Menezes, A.A.A; Ranade, G.; Fernandes, W.A; Naik, D.K.; PrudhviRaju, K.N

    the faults. Besides a possible structural control, the pockmark morphologies are also affected by bottom currents and/or by submarine slumping. The average acoustic backscatter strength from pockmark centre is higher (+ or -35 dB) than the average backscatter...

  9. Applications of the electron backscatter diffraction technique to ceramic materials

    Science.gov (United States)

    Koblischka, M. R.; Koblischka-Veneva, A.

    2013-07-01

    A technique with a relatively high spatial resolution is required for an effective analysis of the microstructure of ceramic materials. The recently developed electron backscatter diffraction (EBSD) technique, which works within a scanning electron microscope, enables a spatially highly resolved study of crystallographic orientations while recording Kikuchi patterns on a user-defined grid. However, such an EBSD texture analysis was until now not often performed on ceramic materials - in contrary, the technique is widely employed in the analysis of metallic materials, including the investigation of various types of steels. The use of ceramics possesses a variety of problems for EBSD investigations like: (i) complicated crystal structure, (ii) difficult surface preparation, and (iii) problems arising from a low conductivity of the ceramic materials. Here, we discuss these problems and present solutions in order to obtain high-quality Kikuchi patterns from such ceramics.

  10. Substrate-mediated zero backscattering from dielectric metasurfaces

    CERN Document Server

    Petrov, Mihail; Baryshnikova, Kseniia; Belov, Pavel

    2015-01-01

    In this work, we study optical properties of all-dielectric metasurfaces on top of the high-index substrate. We show that matching the magnitudes and setting the {\\pi}-phase difference of the electric and magnetic dipole moments in nanoparticles, one can obtain a suppression of reflection from the substrate coated with metasurface. In contrast to homogeneous environment, where zero backscattering, or Kerker effect, is observed when electric and magnetic moments are in-phase, the blooming of the substrate occurs when the out-of-phase condition is satisfied, i.e. for the wavelength between the resonances of electric and magnetic dipole moments. We perform numerical simulations of spherical and disk nanoparticle arrays for different permittivities of the substrate, and confirm our model by numerically separating the contributions into the total reflection from nanoparticle arrays and bare substrate. The influence of high-index substrate is crucial for designing optical metasurfaces and photovoltaic elements with...

  11. Many-beam dynamical simulation of electron backscatter diffraction patterns

    Energy Technology Data Exchange (ETDEWEB)

    Winkelmann, Aimo [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)], E-mail: winkelm@mpi-halle.mpg.de; Trager-Cowan, Carol; Sweeney, Francis [Department of Physics, University of Strathclyde, Glasgow G4 ONG, Scotland (United Kingdom); Day, Austin P. [Aunt Daisy Scientific Ltd., Dixton Rd., Monmouth, Gwent, NP25 3PP (United Kingdom); Parbrook, Peter [EPSRC National Centre for III-V Technologies, University of Sheffield (United Kingdom)

    2007-04-15

    We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{l_brace}0001{r_brace} at 20 kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment.

  12. 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).

  13. 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...

  14. Monte Carlo simulations of landmine detection using neutron backscattering imaging

    Energy Technology Data Exchange (ETDEWEB)

    Datema, Cor P. E-mail: c.datema@iri.tudelft.nl; Bom, Victor R.; Eijk, Carel W.E. van

    2003-11-01

    Neutron backscattering is a technique that has successfully been applied to the detection of non-metallic landmines. Most of the effort in this field has concentrated on single detectors that are scanned across the soil. Here, two new approaches are presented in which a two-dimensional image of the hydrogen distribution in the soil is made. The first method uses an array of position-sensitive {sup 3}He-tubes that is placed in close proximity of the soil. The second method is based on coded aperture imaging. Here, thermal neutrons from the soil are projected onto a detector which is typically placed one to several meters above the soil. Both methods use a pulsed D/D neutron source. The Monte Carlo simulation package GEANT 4 was used to investigate the performance of both imaging systems.

  15. Control of light backscattering in blood during intravenous laser irradiation

    Science.gov (United States)

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

    1997-02-01

    One of the most important problems in modern laser medicine is the determination of system response on laser treatment. Reaction of living system is significant during many kinds of laser procedures like surgery, therapy and biostimulation. Our study was aimed to optimize laser exposure using feed-back fiber system for intravenous laser irradiation of blood (ILIB). This system consisted of helium-neon laser (633 nm, 5 mW) with coupled fiber unit, photodetector and PC interface. Photodetector signals produced due to light backscattering were storaged and processed during all blood irradiation procedure. Significant time-dependent variations were observed within 9-15 min after beginning of treatment procedure and were correlated with number of trials, stage and character of disease. The designed feed-back system allows us to register a human blood response on laser irradiation to achieve better cure effect.

  16. Diffuse Backscattering Mueller Matrices Patterns from Turbid Media

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lian-Shun; ZHU Chen; WANG Zhi-Ping; ZHANG Jing

    2006-01-01

    We present experimental measurements and theory of the diffusely backscattered Mueller matrix patterns that arise from illuminating a turbid medium with a polarized laser beam. Our technique employs polarized light from a He-Ne laser (λ= 632.8 nm) focused onto the surface of the scattering medium. A surface area of approximately 2×2 cm2 centred on the light input point is imaged through polarization analysis optics onto a CCD camera. The Mueller matrix is reconstructed by 49 intensity measurements with various orientations of polarizer and analyser. The measured Mueller matrix of polystyrene spheres is compared with the theory result of incoherent scattering of light by spheres. It shows that the azimuthal patterns of the Mueller matrix are determined by the symmetry of the turbid media and the shape of scattering particles. The result is further proved by experiments with polystyrene spheres of different concentrations in de-ionized water.

  17. Polarized Rayleigh back-scattering from individual semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Duming; Wu Jian; Lu Qiujie; Gutierrez, Humberto R; Eklund, Peter C, E-mail: hur3@psu.edu [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States)

    2010-08-06

    A complete understanding of the interaction between electromagnetic radiation and semiconductor nanowires (NWs) is required in order to further develop a new generation of opto-electronic and photonic devices based on these nanosystems. The reduced dimensionality and high aspect ratio of nanofilaments can induce strong polarization dependence of the light absorption, emission and scattering, leading in some cases to the observation of optical antenna effects. In this work we present the first systematic study of polarized Rayleigh back-scattering from individual crystalline semiconductor NWs with known crystalline structure, orientation and diameters. To explain our experimental Rayleigh polar patterns, we propose a simple theory that relies on a secondary calculation of the volume-averaged internal electromagnetic fields inside the NW. These results revealed that the internal and emitted field can be enhanced depending on the polarization with respect to the NW axis; we also show that this effect strongly depends on the NW diameter.

  18. Results from the Daresbury Compton backscattering X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Laundy, D. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire, WA4 4AD (United Kingdom); Priebe, G. [Max Born Institute, Max-Born-Strasse 2A, 12489 Berlin, DE (Germany); Jamison, S.P. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire, WA4 4AD (United Kingdom); Graham, D.M. [The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Phillips, P.J. [STFC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom); Smith, S.L.; Saveliev, Y. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire, WA4 4AD (United Kingdom); Vassilev, S. [The University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Seddon, E.A., E-mail: elaine.seddon@stfc.ac.uk [The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2012-10-11

    The Daresbury Compton Backscattering X-ray Source uses a high power Ti Sapphire laser interacting in head on geometry with electron bunches in the ALICE energy recovery linear accelerator. X-ray photons with peak energy of 21 keV were generated with the accelerator operating at an energy of 29.6 MeV. The spatial profile of the X-rays emitted near the electron beam axis was measured. The characteristics of the X-ray yield measured as a function of relative timing between the laser pulse and the interacting electron bunch was found to be consistent with the modelled intensity behaviour using measured electron and laser beam parameters.

  19. Determination of RF source power in WPSN using modulated backscattering

    CERN Document Server

    Sreedhar, K

    2012-01-01

    A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations. During RF transmission energy consumed by critically energy-constrained sensor nodes in a WSN is related to the life time system, but the life time of the system is inversely proportional to the energy consumed by sensor nodes. In that regard, modulated backscattering (MB) is a promising design choice, in which sensor nodes send their data just by switching their antenna impedance and reflecting the incident signal coming from an RF source. Hence wireless passive sensor networks (WPSN) designed to operate using MB do not have the lifetime constraints. In this we are going to investigate the system analytically. To obtain interference-free communication connectivity with the WPSN nodes number of RF sources is determined and analyzed i...

  20. 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.

  1. Statistics of vertical backscatter profile of cirrus clouds

    Directory of Open Access Journals (Sweden)

    P. Veglio

    2011-09-01

    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 distributions 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 relation 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 placed near cloud top. As the cloud geometrical thickness increases the BSP maximum shifts towards cloud base. Cloud optical depth and temperature have smaller effect 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.

  2. Feasibility of using backscattered muons for archeological imaging

    Science.gov (United States)

    Bonal, N.; Preston, L. A.

    2013-12-01

    Use of nondestructive methods to accurately locate and characterize underground objects such as rooms and tools found at archeological sites is ideal to preserve these historic sites. High-energy cosmic ray muons are very sensitive to density variation and have been used to image volcanoes and archeological sites such as the Egyptian and Mayan pyramids. Muons are subatomic particles produced in the upper atmosphere that penetrate the earth's crust up to few kilometers. Their absorption rate depends on the density of the materials through which they pass. Measurements of muon flux rate at differing directions provide density variations of the materials between the muon source (cosmic rays and neutrino interactions) and the detector, much like a CAT scan. Currently, muon tomography can resolve features to the sub-meter scale making it useful for this type of work. However, the muon detector must be placed below the target of interest. For imaging volcanoes, the upper portion is imaged when the detector is placed on the earth's surface at the volcano's base. For sites of interest beneath the ground surface, the muon detector would need to be placed below the site in a tunnel or borehole. Placing the detector underground can be costly and may disturb the historical site. We will assess the feasibility of imaging the subsurface using upward traveling muons, to eliminate the current constraint of positioning the detector below the target. This work consists of three parts 1) determine the backscattered flux rate from theory, 2) distinguish backscattered from forward scattered muons at the detector, and 3) validate the theoretical results with field experimentation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. 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.

  4. 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.

  5. Principles of depth-resolved Kikuchi pattern simulation for electron backscatter diffraction.

    Science.gov (United States)

    Winkelmann, A

    2010-07-01

    This paper presents a tutorial discussion of the principles underlying the depth-dependent Kikuchi pattern formation of backscattered electrons in the scanning electron microscope. To illustrate the connections between various electron diffraction methods, the formation of Kikuchi bands in electron backscatter diffraction in the scanning electron microscope and in transmission electron microscopy are compared with the help of simulations employing the dynamical theory of electron diffraction. The close relationship between backscattered electron diffraction and convergent beam electron diffraction is illuminated by showing how both effects can be calculated within the same theoretical framework. The influence of the depth-dependence of diffuse electron scattering on the formation of the experimentally observed electron backscatter diffraction contrast and intensity is visualized by calculations of depth-resolved Kikuchi patterns. Comparison of an experimental electron backscatter diffraction pattern with simulations assuming several different depth distributions shows that the depth-distribution of backscattered electrons needs to be taken into account in quantitative descriptions. This should make it possible to obtain more quantitative depth-dependent information from experimental electron backscatter diffraction patterns via correlation with dynamical diffraction simulations and Monte Carlo models of electron scattering.

  6. Validation of automated supervised segmentation of multibeam backscatter data from the Chatham Rise, New Zealand

    Science.gov (United States)

    Hillman, Jess I. T.; Lamarche, Geoffroy; Pallentin, Arne; Pecher, Ingo A.; Gorman, Andrew R.; Schneider von Deimling, Jens

    2017-01-01

    Using automated supervised segmentation of multibeam backscatter data to delineate seafloor substrates is a relatively novel technique. Low-frequency multibeam echosounders (MBES), such as the 12-kHz EM120, present particular difficulties since the signal can penetrate several metres into the seafloor, depending on substrate type. We present a case study illustrating how a non-targeted dataset may be used to derive information from multibeam backscatter data regarding distribution of substrate types. The results allow us to assess limitations associated with low frequency MBES where sub-bottom layering is present, and test the accuracy of automated supervised segmentation performed using SonarScope® software. This is done through comparison of predicted and observed substrate from backscatter facies-derived classes and substrate data, reinforced using quantitative statistical analysis based on a confusion matrix. We use sediment samples, video transects and sub-bottom profiles acquired on the Chatham Rise, east of New Zealand. Inferences on the substrate types are made using the Generic Seafloor Acoustic Backscatter (GSAB) model, and the extents of the backscatter classes are delineated by automated supervised segmentation. Correlating substrate data to backscatter classes revealed that backscatter amplitude may correspond to lithologies up to 4 m below the seafloor. Our results emphasise several issues related to substrate characterisation using backscatter classification, primarily because the GSAB model does not only relate to grain size and roughness properties of substrate, but also accounts for other parameters that influence backscatter. Better understanding these limitations allows us to derive first-order interpretations of sediment properties from automated supervised segmentation.

  7. A Multivariate Correlation Analysis of High- Frequency Bottom Backscattering Strength Measurements With Geotechnical Parameters

    OpenAIRE

    2007-01-01

    Sound backscattered from the seabed has been measured in a 10x10-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 30 from the horizontal. Fifty bottom-grab samples, representative of the uppermost 20 cm, were taken and analyzed for gravel content, shell content, and grain-size distribution. The backscatter measu...

  8. Diffuse optical microscopy for quantification of depth-dependent epithelial backscattering in the cervix

    Science.gov (United States)

    Bodenschatz, Nico; Lam, Sylvia; Carraro, Anita; Korbelik, Jagoda; Miller, Dianne M.; McAlpine, Jessica N.; Lee, Marette; Kienle, Alwin; MacAulay, Calum

    2016-06-01

    A fiber optic imaging approach is presented using structured illumination for quantification of almost pure epithelial backscattering. We employ multiple spatially modulated projection patterns and camera-based reflectance capture to image depth-dependent epithelial scattering. The potential diagnostic value of our approach is investigated on cervical ex vivo tissue specimens. Our study indicates a strong backscattering increase in the upper part of the cervical epithelium caused by dysplastic microstructural changes. Quantization of relative depth-dependent backscattering is confirmed as a potentially useful diagnostic feature for detection of precancerous lesions in cervical squamous epithelium.

  9. Backscattering factor measurements of gamma rays of the different thickness of pure concrete

    OpenAIRE

    B.A. Almayahi

    2015-01-01

    Backscattering peak is one of the main features of the pulse height spectrum from a gamma ray detector. This arises mainly from materials outside like source baking, photomultiplier tube housing, shielding etc. The effect of source backing on the relative importance of the backscattered peak for gamma ray using a NaI (Tl) scintillation detector is measured. Gamma energies in the range from 0.088 MeV to 1.253 MeV are used. Backscattering factor (Fb) measurements have been carried out (2 > Fb ≥...

  10. Temperature dependence of erythrocyte aggregation in vitro by backscattering nephelometry

    Science.gov (United States)

    Sirko, Igor V.; Firsov, Nikolai N.; Ryaboshapka, Olga M.; Priezzhev, Alexander V.

    1997-05-01

    We apply backscattering nephelometry technique to register the alterations of the scattering signal from a whole blood sample due to appearance or disappearance of different types of erythrocyte aggregates in stasis and under controlled shear stress. The measured parameters are: the characteristic times of linear and 3D aggregates formation, and the strength of aggregates of different types. These parameters depend on the sample temperature in the range of 2 divided by 50 degrees C. Temporal parameters of the aggregation process strongly increase at temperature 45 degrees C. For samples of normal blood the aggregates strength parameters do not significantly depend on the sample temperature, whereas for blood samples from patients suffering Sjogren syndrome we observe high increase of the strength of 3D and linear aggregates and decrease of time of linear aggregates formation at low temperature of the sample. This combination of parameters is opposite to that observed in the samples of pathological blood at room temperature. Possible reasons of this behavior of aggregation state of blood and explanation of the observed effects will be discussed.

  11. Electron backscattering in a cavity: Ballistic and coherent effects

    Science.gov (United States)

    Kozikov, A. A.; Weinmann, D.; Rössler, C.; Ihn, T.; Ensslin, K.; Reichl, C.; Wegscheider, W.

    2016-11-01

    Numerous experimental and theoretical studies have focused on low-dimensional systems locally perturbed by the biased tip of a scanning force microscope. In all cases either open or closed weakly gate-tunable nanostructures have been investigated, such as quantum point contacts, open or closed quantum dots, etc. We study the behavior of the conductance of a quantum point contact with a gradually forming adjacent cavity in series under the influence of a scanning gate. Here, an initially open quantum point contact system gradually turns into a closed cavity system. We observe branches and interference fringes known from quantum point contacts coexisting with irregular conductance fluctuations. Unlike the branches, the fluctuations cover the entire area of the cavity. In contrast to previous studies, we observe and investigate branches under the influence of the confining stadium potential, which is gradually built up. We find that the branches exist only in the area surrounded by cavity top gates. As the stadium shrinks, regular fringes originate from tip-induced constrictions leading to quantized conduction. In addition, we observe arclike areas reminiscent of classical electron trajectories in a chaotic cavity. We also argue that electrons emanating from the quantum point contact spread out like a fan leaving branchlike regions of enhanced backscattering.

  12. Crystallographic Orientation of Cuttlebone Shield Determined by Electron Backscatter Diffraction

    Science.gov (United States)

    Cusack, Maggie; Chung, Peter

    2014-01-01

    In common with many cephalopod mollusks, cuttlefish produce an internal biomineral buoyancy device. This cuttlebone is analogous to a surf board in shape and structure, providing rigidity and a means of controlling buoyancy. The cuttlebone is composed of calcium carbonate in the form of aragonite and comprises an upper dorsal shield and a lower lamellar matrix. The lamellar matrix comprises layers of chambers with highly corrugated walls. The dorsal shield comprises bundles of aragonite needles stacked on top of each other. Electron backscatter diffraction analyses of the dorsal shield reveal that the c-axis of aragonite is parallel with the long axis of the needles in the bundles such that any spread in crystallographic orientation is consistent with the spread in orientation of the fibers as they radiate to form the overall structure of the dorsal shield. This arrangement of c-axis coincident with the long axis of the biomineral structure is similar to the arrangement in corals and in contrast to the situation in the molluskan aragonite nacre of brachiopod calcite where the c-axis is perpendicular to the aragonite tablet or calcite fiber, respectively.

  13. Lattice constant measurement from electron backscatter diffraction patterns.

    Science.gov (United States)

    Saowadee, N; Agersted, K; Bowen, J R

    2017-02-20

    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 analysis. In this study, lattice constants of cubic STN and cubic YSZ in the pure materials and in co-sintered composites were measured from their EBSPs acquired at 10 kV using a silicon single crystal as a calibration reference. The EBSP distortion was corrected by spherical back projection and Kikuchi band analysis was made using in-house software. The error of the lattice constant measurement was determined to be in the range of 0.09-1.12% compared to values determined by XRD and from literature. The confidence level of the method is indicated by the standard deviation of the measurement, which is approximately 0.04 Å. Studying Kikuchi band size dependence of the measurement precision shows that the measurement error decays with increasing band size (i.e. decreasing lattice constant). However, in practice, the sharpness of wide bands tends to be low due to their low intensity, thus limiting the measurement precision. Possible methods to improve measurement precision are suggested.

  14. Simulation of Rutherford backscattering spectrometry from arbitrary atom structures

    Science.gov (United States)

    Zhang, S.; Nordlund, K.; Djurabekova, F.; Zhang, Y.; Velisa, G.; Wang, T. S.

    2016-10-01

    Rutherford backscattering spectrometry in a channeling direction (RBS/C) is a powerful tool for analysis of the fraction of atoms displaced from their lattice positions. However, it is in many cases not straightforward to analyze what is the actual defect structure underlying the RBS/C signal. To reveal insights of RBS/C signals from arbitrarily complex defective atomic structures, we develop here a method for simulating the RBS/C spectrum from a set of arbitrary read-in atom coordinates (obtained, e.g., from molecular dynamics simulations). We apply the developed method to simulate the RBS/C signals from Ni crystal structures containing randomly displaced atoms, Frenkel point defects, and extended defects, respectively. The RBS/C simulations show that, even for the same number of atoms in defects, the RBS/C signal is much stronger for the extended defects. Comparison with experimental results shows that the disorder profile obtained from RBS/C signals in ion-irradiated Ni is due to a small fraction of extended defects rather than a large number of individual random atoms.

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Influence of lithium coating on the optics of Doppler backscatter system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X. H.; Liu, A. D., E-mail: lad@ustc.edu.cn; Zhou, C.; Hu, J. Q.; Wang, M. Y.; Yu, C. X.; Liu, W. D.; Li, H.; Lan, T.; Xie, J. L. [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-10-15

    This paper presents the first investigation of the effect of lithium coating on the optics of Doppler backscattering. A liquid lithium limiter has been applied in the Experimental Advanced Superconducting Tokamak (EAST), and a Doppler backscattering has been installed in the EAST. A parabolic mirror and a flat mirror located in the vacuum vessel are polluted by lithium. An identical optical system of the Doppler backscattering is set up in laboratory. The power distributions of the emission beam after the two mirrors with and without lithium coating (cleaned before and after), are measured at three different distances under four incident frequencies. The results demonstrate that the influence of the lithium coating on the power distributions are very slight, and the Doppler backscattering can work normally under the dosage of lithium during the 2014 EAST campaign.

  1. 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...

  2. Brillouin backscattering from a double-pulse CO/sub 2/ laser incident on planar targets

    Energy Technology Data Exchange (ETDEWEB)

    Decoste, R.; Lavigne, P.; Pepin, H.; Mitchel, G.R.; Kieffer, J.

    1982-05-01

    The Brillouin backscattering instability is studied for a range of preformed plasma conditions and using a CO/sub 2/ laser in the 10/sup 12/--10/sup 13/ W/cm/sup 2/ regime. A short prepulse is incident on a planar target ahead of the main-pulse to produce the preformed plasma. The instability appears in a short burst of back-reflected light. Saturation of the backscatter level is observed for an individual increase of the prepulse energy, main-pulse intensity, and prepulse-to-main-pulse delay. Ion Landau damping is strong and average back-reflected intensities are limited to less than 30% of incident. Backscattered light spectra suggest that the critical surface is involved in the backscatter process when the laser beam is at best focus onto the target surface. Otherwise, the spectral signature is similar to those obtained from underdense plasmas.

  3. Backscattering Light Model of Seawater for Modulated Lidar Based on the Stationarity of Light Field

    Institute of Scientific and Technical Information of China (English)

    JI Hang; MA Yong; LIANG Kun; WANG Hong-yuan

    2007-01-01

    The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultrashort pulsed laser and i t is effective to suppress the backscattering to adopt the coherent detection technology by identifying the modulation envelope. A nonstationary light field is formed in seawater by the ultrashort pulsed laser. The inherent relationship between the nonstationary light field formed by modulated lidar and the stationary light field formed by conventional lidar was discussed and the backscattering light model of the stationary light field for the ultrashort pulsed laser was proposed. The backscattering signal in modulated lidar system was processed and analyzed in the frequency domain on the basis of the model.

  4. 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....

  5. Landmine detection method combined with backscattering neutrons and capture {gamma}-rays from hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yoshiyuki, E-mail: ytaka@rri.kyoto-u.ac.j [Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Misawa, Tsuyoshi; Pyeon, Cheol Ho; Shiroya, Seiji [Research Reactor Institute, Kyoto University, Asashiro-nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Yoshikawa, Kiyoshi [Institute of Advanced Energy, Kyoto University, Gokashou, Uji-shi, Kyoto 611-0011 (Japan)

    2011-07-15

    The usefulness of the measurements of the backscattering neutron and 2.22 MeV capture {gamma}-ray from hydrogen in the landmine detection method is described in this paper. When the soil moisture content is increased, the reaction rates of both the neutron scattering reaction and capture reaction are increased. However, the backscattering neutrons are more influenced than the capture {gamma}-rays by the soil moisture before the reaction with the detector. The facts that the backscattering neutron method is useful in the dry soil case and that the capture {gamma}-ray method is effective in well-wet soil case are confirmed by the experiments and the calculations. The landmine detection efficiency is improved in various soil moisture conditions by combining the backscattering neutron method together with the capture {gamma}-ray method. The effectiveness of the pulse mode operation was confirmed numerically.

  6. Landmine detection method combined with backscattering neutrons and capture γ-rays from hydrogen.

    Science.gov (United States)

    Takahashi, Yoshiyuki; Misawa, Tsuyoshi; Pyeon, Cheol Ho; Shiroya, Seiji; Yoshikawa, Kiyoshi

    2011-07-01

    The usefulness of the measurements of the backscattering neutron and 2.22MeV capture γ-ray from hydrogen in the landmine detection method is described in this paper. When the soil moisture content is increased, the reaction rates of both the neutron scattering reaction and capture reaction are increased. However, the backscattering neutrons are more influenced than the capture γ-rays by the soil moisture before the reaction with the detector. The facts that the backscattering neutron method is useful in the dry soil case and that the capture γ-ray method is effective in well-wet soil case are confirmed by the experiments and the calculations. The landmine detection efficiency is improved in various soil moisture conditions by combining the backscattering neutron method together with the capture γ-ray method. The effectiveness of the pulse mode operation was confirmed numerically.

  7. 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...

  8. Simulation of positron backscattering and implantation profiles using Geant4 code

    Institute of Scientific and Technical Information of China (English)

    黄世娟; 潘子文; 刘建党; 韩荣典; 叶邦角

    2015-01-01

    For the proper interpretation of the experimental data produced in slow positron beam technique, the positron im-plantation properties are studied carefully using the latest Geant4 code. The simulated backscattering coefficients, the implantation profiles, and the median implantation depths for mono-energetic positrons with energy range from 1 keV to 50 keV normally incident on different crystals are reported. Compared with the previous experimental results, our simula-tion backscattering coefficients are in reasonable agreement, and we think that the accuracy may be related to the structures of the host materials in the Geant4 code. Based on the reasonable simulated backscattering coefficients, the adjustable parameters of the implantation profiles which are dependent on materials and implantation energies are obtained. The most important point is that we calculate the positron backscattering coefficients and median implantation depths in amorphous polymers for the first time and our simulations are in fairly good agreement with the previous experimental results.

  9. 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....

  10. 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...

  11. Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment.

    Science.gov (United States)

    Ramnarine, K V; Hoskins, P R; Routh, H F; Davidson, F

    1999-01-01

    The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.

  12. 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...

  13. 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).

  14. NONINVASIVE MEASUREMENT OF LOCAL THERMAL DIFFUSIVITY USING BACKSCATTERED ULTRASOUND AND FOCUSED ULTRASOUND HEATING

    OpenAIRE

    2008-01-01

    Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create...

  15. 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

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

    Science.gov (United States)

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

    2014-01-01

    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 their derivatives

  17. Nonlinear frequency shift in Raman backscattering and its implications for plasma diagnostics

    Science.gov (United States)

    Kaganovich, D.; Hafizi, B.; Palastro, J. P.; Ting, A.; Helle, M. H.; Chen, Y.-H.; Jones, T. G.; Gordon, D. F.

    2016-12-01

    Raman backscattered radiation of intense laser pulses in plasmas is investigated for a wide range of intensities relevant to laser wakefield acceleration. The weakly nonlinear dispersion relation for Raman backscattering predicts an intensity and density dependent frequency shift that is opposite to that suggested by a simple relativistic consideration. This observation has been benchmarked against experimental results, providing a novel diagnostic for laser-plasma interactions.

  18. Nonlinear Frequency Shift in Raman Backscattering and its Implications for Plasma Diagnostics

    CERN Document Server

    Kaganovich, D; Palastro, J P; Ting, A; Helle, M H; Chen, Y -H; Jones, T G; Gordon, D F

    2016-01-01

    Raman backscattered radiation of intense laser pulses in plasma is investigated for a wide range of intensities relevant to laser wakefield acceleration. The weakly nonlinear dispersion relation for Raman backscattering predicts an intensity and density dependent frequency shift that is opposite to that suggested by a simple relativistic consideration. This observation has been benchmarked against experimental results, providing a novel diagnostic for laser-plasma interactions.

  19. 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

  20. Interlaboratory comparison of backscatter coefficient estimates for tissue-mimicking phantoms.

    Science.gov (United States)

    Anderson, Janelle J; Herd, Maria-Teresa; King, Michael R; Haak, Alexander; Hafez, Zachary T; Song, Jun; Oelze, Michael L; Madsen, Ernest L; Zagzebski, James A; O'Brien, William D; Hall, Timothy J

    2010-01-01

    Ultrasonic backscatter is useful for characterizing tissues and several groups have reported methods for estimating backscattering properties. Previous interlaboratory comparisons have been made to test the ability to accurately estimate the backscatter coefficient (BSC) by different laboratories around the world. Results of these comparisons showed variability in BSC estimates but were acquired only for a relatively narrow frequency range, and, most importantly, lacked reference to any independent predictions from scattering theory. The goal of this study was to compare Faran-scattering-theory predictions with cooperatively-measured backscatter coefficients for low-attenuating and tissue-like attenuating phantoms containing glass sphere scatterers of different sizes for which BSCs can independently be predicted. Ultrasonic backscatter measurementswere made for frequencies from 1 to 12 MHz. Backscatter coefficients were estimated using two different planar-reflector techniques at two laboratories for two groups of phantoms. Excellent agreement was observed between BSC estimates from both laboratories. In addition, good agreement with the predictions of Faran's theory was obtained, with average fractional (bias) errors ranging from 8-14%. This interlaboratory comparison demonstrates the ability to accurately estimate parameters derived from the BSC, including an effective scatterer size and the acoustic concentration, both of which may prove useful for diagnostic applications of ultrasound tissue characterization.

  1. Improvement of a 3D radar backscattering model using matrix-doubling method

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Radiative transfer models have been widely used to simulate the radar backscattering from forested areas. A three-dimensional radar backscatter model of forest canopy developed in previous studies takes full account of spatial position of trees in a forest stand, and the interactions among crown, trunk and ground surface. The model predicted well for the co-polarized backscatter measurements, but underestimated the backscattering for cross-polarization, primarily because only the first-order scattering within tree crowns was considered in the model. The backscattering at cross-polarization depends strongly on multiple scatter- ing within tree crowns. To produce good estimations for cross-polarized component, the matrix-doubling method is employed here to compute multiple-scattering within the crown. The modified model is compared with the original model, and the field forest measurements and AIRSAR data are used for validation of the modified model. The cross-polarization backscattering is improved in different degrees for different crown structures and at different bands.

  2. 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.

  3. Combination of multibeam backscatter and bathymetry: A method to characterize the sea floor

    Science.gov (United States)

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

    2003-04-01

    A high resolution multibeam survey was conducted by the RV "Polarstern" in order to identify and map locations of carbonate mounds in the Porcupine Seabight west of Ireland utilizing the multibeam echo sounder Hydrosweep DS-2. The scientific interest of that area rose due to an expected link between the carbonate mounds and subsurface hydrocarbon resources. In addition to the depths measurements the acoustic intensity of the received echo was recorded for individual measurements. After processing of the echo amplitudes by employing NRGCOR software the backscatter strength of the ensonified seafloor is used to identify areas of similar physical properties. Normalization was applied to the backscatter data to obtain acoustic response information which is independent from the incidence angle of the sonar beam. The mapped grey scale variation of the acoustic response is used to separate different types of seafloor. Four distinct types of seafloor have been depicted which are mounds, buried mounds, channel seafloor and inter channel areas. A semi-empirical method was applied to determine shape aspects of the angular backscatter strength. Three parameters, i.e. predicted 20° angular response, slope and coefficient of variation of the angular backscatter responses were computed to understand varying seafloor characteristics. The combination of backscatter and bathymetric data is another significant aspect of this contribution. Applying 3D visualisation techniques enables the user to link acoustic backscatter response to the seafloor morphology.

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

    Science.gov (United States)

    Takahira, Hiroyuki; Ogasawara, Toshiyuki; Mori, Naoto; Tanaka, Moe

    2015-10-01

    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 t0 to a characteristic time of wave propagation tS, η = t0/ts, 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.

  5. Predicting seabed properties from acoustic backscatter on the UK continental shelf (Invited)

    Science.gov (United States)

    McGonigle, C.; Collier, J.

    2010-12-01

    The relationship between backscatter imagery, sediment grain size and measures of biological community diversity are investigated using a quantitative approach at an aggregate extraction site in the Southern North Sea, UK. Previous work conducted at Oban in Scotland (Collier and Brown, 2005) showed the potential for estimating sediment grain size from first order backscatter statistics. In particular this study reported r2 correlation values of 0.531 between mean backscatter and mean sediment grain size, with r2=0.351 between standard deviation backscatter and sediment grain size sorting (n=19). Here we test these simple linear relationships in a different environment where the sediments are coarser and the degree of sorting is lower. We present the analysis of a dataset collected in 2008 off the coast of East Anglia, UK. Beam-time series backscatter imagery was acquired from a 300 kHz source MBES (Kongsberg Simard EM3000D), and ground-truth data obtained from a series of 100 Hamon and 16 Clamshell grabs processed for particle size analysis. Pixels were extracted from 32-bit backscatter imagery at 50 m2 window based on the ground-truth data locations. So far 19 of the 100 Hamon samples have been processed. These show a significant correlation between mean backscatter intensity and mean sediment grain size (r2=0.427). The level of agreement between standard deviation backscatter and grain size distribution however, was lower at r2=0.078. Correlation of univariate measures of biological diversity and mean backscatter were low for the 19 samples; the maximum observed value was r2=0.074 (Fisher’s diversity index). Relative to the standard deviation backscatter, the strongest correlation was r2=0.192 (Brillion’s). The analysis of the Clamshell samples is completed. In this case, the MBES backscatter imagery established a stronger positive correlation (r2=0.628) between the means. The level of agreement observed between the standard deviation of the backscatter and

  6. 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.

  7. 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

  8. 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.

  9. Quantitative measurements of Kikuchi bands in diffraction patterns of backscattered electrons using an electrostatic analyzer.

    Science.gov (United States)

    Went, M R; Winkelmann, A; Vos, M

    2009-09-01

    Diffraction patterns of backscattered electrons can provide important crystallographic information with high spatial resolution. Recently, the dynamical theory of electron diffraction was applied to reproduce in great detail backscattering patterns observed in the scanning electron microscope (SEM). However, a fully quantitative comparison of theory and experiment requires angle-resolved measurements of the intensity and the energy of the backscattered electrons, which is difficult to realize in an SEM. This paper determines diffraction patterns of backscattered electrons using an electrostatic analyzer, operating at energies up to 40 keV with sub-eV energy resolution. Measurements are done for different measurement geometries and incoming energies. Generally a good agreement is found between theory and experiment. This spectrometer also allows us to test the influence of the energy loss of the detected electron on the backscattered electron diffraction pattern. It is found that the amplitude of the intensity variation decreases only slowly with increasing energy loss from 0 to 60 eV.

  10. 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.

  11. 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.

  12. 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.

  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. A real-time measure of cavitation induced tissue disruption by ultrasound imaging backscatter reduction.

    Science.gov (United States)

    Hall, Timothy L; Fowlkes, J Brian; Cain, Charles A

    2007-03-01

    A feedback method for obtaining real-time information on the mechanical disruption of tissue through ultrasound cavitation is presented. This method is based on a substantial reduction in ultrasound imaging backscatter from the target volume as the tissue structure is broken down. Ex-vivo samples of porcine liver were exposed to successive high-intensity ultrasound pulses at a low duty cycle to induce mechanical disruption of tissue parenchyma through cavitation (referred to as histotripsy). At the conclusion of treatment, B-scan imaging backscatter was observed to have decreased by 22.4 +/- 2.3 dB in the target location. Treated samples of tissue were found to contain disrupted tissue corresponding to the imaged hypoechoic volume with no remaining discernable structure and a sharp boundary. The observed, substantial backscatter reduction may be an effective feedback mechanism for assessing treatment efficacy in ultrasound surgery using pulsed ultrasound to create cavitation.

  15. 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.

  16. Generation of attosecond x-ray and gamma-ray via Compton backscattering.

    Science.gov (United States)

    Chung, Sang-Young; Yoon, Moohyun; Kim, Dong Eon

    2009-05-11

    The generation of an isolated attosecond gamma-ray pulse utilizing Compton backscattering of a relativistic electron bunch has been investigated. The energy of the electron bunch is modulated while the electron bunch interacts with a co-propagating few-cycle CEP (carrier envelope phase)-locked laser in a single-period wiggler. The energy-modulated electron bunch interacts with a counter-propagating driver laser, producing Compton back-scattered radiation. The energy modulation of the electron bunch is duplicated to the temporal modulation of the photon energy of Compton back-scattered radiation. The spectral filtering using a crystal spectrometer allows one to obtain an isolated attosecond gamma-ray.

  17. Experimental observation of backscattered light based on different coherence between incident laser beams

    Institute of Scientific and Technical Information of China (English)

    Xiangfu; Meng; Chen; Wang; Honghai; An; Guo; Jia; Huazhen; Zhou; Sizu; Fu

    2013-01-01

    Recent experimental results on NIF revealed a much higher stimulated Brillouin scattering(SBS)and stimulated Raman scattering(SRS)backscatter than expected;one possible reason was due to the coherence between incident laser beams.In our research,two laser beams(~1 ns,~250 J,527 nm in each one)with different coherent degrees between them from the SG-II facility were employed to irradiate an Au plate target;the backscatter of SBS and SRS in the range of the given solid angle had been measured.The results showed that it could change dramatically corresponding to the difference of the coherent degree between the two laser beams,and there was usually more intense backscatter the higher the coherent degree between the incident beams.

  18. 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.

  19. Variations in backscatter observed in PMMA whole-body dosimetry slab phantoms.

    Science.gov (United States)

    Schwahn, Scott O; Gesell, Thomas F

    2008-01-01

    Polymethyl methacrylate (PMMA) is a useful material for dosimetry phantoms in many ways including approximate tissue equivalence, stability, accessibility and ease of use. However, recent studies indicate that PMMA may have some unanticipated variation in backscatter from one phantom to another. While the reasons behind the variations have not been identified, it has been demonstrated that the backscatter from one phantom to another may vary by as much as 15%, resulting in a dosemeter response variation of as much as 5%. This unexpected contribution to uncertainty in delivered dose to a dosemeter may be quite large compared to the normally estimated uncertainty, potentially causing problems with calibration and performance testing. This paper includes data supporting the differences in backscatter among phantoms, and results from tests on the phantoms performed in an effort to identify possible causes.

  20. Low-coherence enhanced backscattering: review of principles and applications for colon cancer screening

    Science.gov (United States)

    Kim, Young L.; Liu, Yang; Turzhitsky, Vladimir M.; Roy, Hemant K.; Wali, Ramesh K.; Subramanian, Hariharan; Pradhan, Prabhakar; Backman, Vadim

    2006-07-01

    The phenomenon of enhanced backscattering (EBS) of light, also known as coherent backscattering (CBS) of light, has been the object of intensive investigation in nonbiological media over the last two decades. However, there have been only a few attempts to explore EBS for tissue characterization and diagnosis. We have recently made progress in the EBS measurements in tissue by taking advantage of low spatial coherence illumination, which has led us to the development of low-coherence enhanced backscattering (LEBS) spectroscopy. In this work, we review the current state of research on LEBS. After a brief discussion of the basic principle of EBS and LEBS, we present an overview of the unique features of LEBS for tissue characterization, and show that LEBS enables depth-selective spectroscopic assessment of mucosal tissue. Then, we demonstrate the potential of LEBS spectroscopy for predicting the risk of colon carcinogenesis and colonoscopy-free screening for colorectal cancer (CRC).

  1. Backscattering factor measurements of gamma rays of the different thickness of pure concrete

    Directory of Open Access Journals (Sweden)

    B.A. Almayahi

    2015-07-01

    Full Text Available Backscattering peak is one of the main features of the pulse height spectrum from a gamma ray detector. This arises mainly from materials outside like source baking, photomultiplier tube housing, shielding etc. The effect of source backing on the relative importance of the backscattered peak for gamma ray using a NaI (Tl scintillation detector is measured. Gamma energies in the range from 0.088 MeV to 1.253 MeV are used. Backscattering factor (Fb measurements have been carried out (2 > Fb ≥ 1 of various pure concrete thickness from 2 cm to 30 cm.

  2. Bathymetry and acoustic backscatter-outer mainland shelf, eastern Santa Barbara Channel, California

    Science.gov (United States)

    Dartnell, Peter; Finlayson, David P.; Ritchie, Andrew C.; Cochrane, Guy R.; Erdey, Mercedes D.

    2012-01-01

    In 2010 and 2011, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from the outer shelf region of the eastern Santa Barbara Channel, California. These surveys were conducted in cooperation with the Bureau of Ocean Energy Management (BOEM). BOEM is interested in maps of hard-bottom substrates, particularly natural outcrops that support reef communities in areas near oil and gas extraction activity. The surveys were conducted using the USGS R/V Parke Snavely, outfitted with an interferometric sidescan sonar for swath mapping and real-time kinematic navigation equipment. This report provides the bathymetry and backscatter data acquired during these surveys in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

  3. Laser remote sensing of tropospheric aerosol over Southern Ireland using a backscatter Raman LIDAR

    Science.gov (United States)

    Ruth, Albert A.; Acheson, Karen; Apituley, Arnoud; Chaikovsky, Anatoli; Nicolae, Doina; Ortiz-Amezcua, Pablo; Stoyanov, Dimitar; Trickl, Thomas

    2016-04-01

    Raman backscatter coefficients, extinction coefficients and lidar ratios were measured with a ground based Raman lidar system at University College Cork, Ireland, during the periods of July 2012 - August 2012, April 2013 - December 2013 and March 2014 - May 2014. Statistical analysis of these parameters in this time provided information about seasonal effects of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer. The mean of the altitude of the top of the planetary boundary layer over these time periods is 950 ± 302 m. The values are larger in summer, 1206 ± 367 m, than in winter, 735 m. The altitude of the top of the planetary boundary layer measured at Cork is lower than most EARLINET stations. Raman backscatter coefficients above and altitude of 2 km are highest in summer and spring where the values are greater than 0.28 Mm-1 sr-1. Winter values of Raman backscatter coefficient are less than 0.06 Mm-1 sr-1. These seasonal effects are consistent with most EARLINET stations. Large aerosol loads were detected in July 2013 due to a Canadian forest fire event. HYSPLIT air-mass back trajectory models were used to trace the origin of the detected aerosol layers. The aerosol forecast model, MACC, was used to further investigate and verify the propagation of the smoke. The Lidar ratio values and Klett and Raman backscatter coefficients at Cork, for the 4th July, the 7th to 9th of July and the 11th July were compared with observations at Cabauw, Minsk, Granada, Bucharest, Sofia and Garmisch. Lidar ratio values for the smoke detected at Cork were determined to be between 33 sr and 62 sr. The poster will discuss the seasonal changes of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer at Cork. An investigation of a Canadian forest fire event measured at Cork will be compared with other data from the EARLINET database.

  4. 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.

  5. 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

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

    Science.gov (United States)

    Beyer, Andreas; Chakraborty, Bishwajit; Schenke, Hans Werner

    2007-02-01

    In this study multibeam angular backscatter data acquired in the eastern slope of the Porcupine Seabight are analysed. Processing of the angular backscatter data using the ‘NRGCOR’ software was made for 29 locations comprising different geological provinces like: carbonate mounds, buried mounds, seafloor channels, and inter-channel areas. A detailed methodology is developed to produce a map of angle-invariant (normalized) backscatter data by correcting the local angular backscatter values. The present paper involves detailed processing steps and related technical aspects of the normalization approach. The presented angle-invariant backscatter map possesses 12 dB dynamic range in terms of grey scale. A clear distinction is seen between the mound dominated northern area (Belgica province) and the Gollum channel seafloor at the southern end of the site. Qualitative analyses of the calculated mean backscatter values i.e., grey scale levels, utilizing angle-invariant backscatter data generally indicate backscatter values are highest (lighter grey scale) in the mound areas followed by buried mounds. The backscatter values are lowest in the inter-channel areas (lowest grey scale level). Moderate backscatter values (medium grey level) are observed from the Gollum and Kings channel data, and significant variability within the channel seafloor provinces. The segmentation of the channel seafloor provinces are made based on the computed grey scale levels for further analyses based on the angular backscatter 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 computed at 20° is the highest for the mound areas. The coefficient of variation (CV) of the mean backscatter response is also the highest for the mound areas. Interestingly, the slope value of the buried mound areas are

  7. Revisit to the symmetry relations in diffusely backscattered polarization patterns of turbid media

    Institute of Scientific and Technical Information of China (English)

    Yinqi Feng

    2006-01-01

    As there exists an inconsistency in claiming the symmetrical relations in the 16 Mueller matrix elements used to describe a turbid medium, the author restudies the symmetrical relationships between diffusely backscattered polarization patterns in isotropic turbid media and simulates all two-dimensional elements of diffusely backscattered Mueller matrix in both cases of Rayleigh and Mie scatterings using the doublescattering approximation and the Monte Carlo algorithm, respectively. The previous experimental observatious are compared with the numerically determined matrix elements, showing a good agreement in both double-scattering model and Monte Carlo simulation. The symmetrical relations between the Mueller matrix elements are clarified.

  8. Relationship between the fraction of backscattered light and the asymmetry parameter

    Science.gov (United States)

    Horvath, Helmuth

    2015-04-01

    The fraction of backscattered light is defined as the ratio of the integral of the volume scattering function over the backward half solid angle divided by the integral of the volume scattering function over the full solid angle. It can be measured with an integrating nephelometer. On the other hand the asymmetry parameter is the integral over the full solid angle of the volume scattering function weighted with the cosine of the scattering angle divided by the integral of the volume scattering function. To determine the asymmetry parameter the measurement of the angular dependence of the volume scattering function is needed, which can be obtained e.g. with a polar nephelometer. The asymmetry parameter is an important input parameter for radiative transfer calculations in order to obtain information of effects of the atmospheric aerosol effects (climate, screening, visibility, and others). Unfortunately measurements of the asymmetry parameter of the atmospheric aerosol are scarce. It is obvious, that a relation between the asymmetry parameter and the backscattered fraction should exist: the smaller the backscattered fraction, the more asymmetric the scattering, thus the larger the asymmetry parameter. A large set of 6500 angular scattering data have been obtained at various locations of the world: Vienna (Austria), Kyoto (Japan), Granada (Spain) and Palencia (Spain). The aerosols in these locations were considerably different, ranging from continental, urban, maritime, to desert dust. The volume scattering function has been measured between 5° and 175° , the values for 0° to 5° and 175° to 180° have been obtained by extrapolation of the shape of the curve, thus the whole range of scattering angles was available for calculating the backscattered fraction and the asymmetry parameter of the aerosol. PIC A summary of all data is shown in figure 1. The majority of the data points suggest an unanimous relation between backscattering and asymmetry parameter. The

  9. Inversion of dielectric constant and moisture of bare soil surface from backscattering coefficient

    Institute of Scientific and Technical Information of China (English)

    李宗谦; 冯孔豫

    1997-01-01

    An inverse method of dielectric constant and moisture of bare wet soil surface from backscattering coefficients is presented, which is based upon the small perturbation model of electromagnetic wave scattering from rough surfaces and the empirical and dielectric mixing models of wet soil. Some sets of curves which describe the relation between the moisture of soil and the ratio of like polarization backscattering coefficients σvv and σhh are obtained, and some principles on how to choose the incident frequencies and the incident angles of the electromagnetic wave are given Analysis and calculation show that the mam advantage of this inverse method is its efficiency and simplicity.

  10. [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

  11. Elimination of coherent Rayleigh backscatter induced noise in fibre Michelson interferometers

    Science.gov (United States)

    Marrone, M. J.; Kersey, A. D.; Villarruel, C. A.; Kirkendall, C. K.; Dandridge, A.

    1992-09-01

    Attention is given to a technique for the elimination of coherent Rayleigh backscatter induced phase noise in remotely addressed Michelson interferometer systems. The technique, which allows high sensitivity measurements over long input/output fiber leads, is based on the use of commercial polarization insensitive isolators and is completely passive in its operation. Faraday-rotator and mirror devices for the reflectors in the Michelson interferometer are used to demonstrate a practical fiber sensor configuration for remote applications that is both free of polarization-induced signal fading and insensitive to Rayleigh backscattering effects.

  12. Calculations of Backscattering Mueller Matrices for Turbid Media with a Sphere Queue Model

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-Hua; LI Zhen-Hua; LAI Jian-Cheng; ZHANG Ying-Ying; HE An-Zhi

    2006-01-01

    A sphere queue model is introduced to calculate Mueller matrices of turbid media. Combined with the single scattering approximation, the backscattering Mueller matrices of turbid media can be computed rapidly by Mie theory. The numerical results agree with the azimuthal dependences of backscattering Mueller matrices' patterns from turbid media, which indicates that the major contribution to the Mueller matrices' patterns comes from the single scattering of the sphere queue, and the multiple scattering considered as a high-order correction does not change the patterns. The numerical analysis reveals that the contrast of Mueller matrices' patterns will decrease with increase of the concentration of media and the distance from the incident point.

  13. Three-dimensional imaging of hidden objects using positron emission backscatter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwon [Los Alamos National Laboratory; Cowee, Misa [Los Alamos National Laboratory; Fenimore, Ed [Los Alamos National Laboratory; Galassi, Mark [Los Alamos National Laboratory; Looker, Quinn [Los Alamos National Laboratory; Mcneil, Wendy V [Los Alamos National Laboratory; Stonehill, Laura [Los Alamos National Laboratory; Wallace, Mark [Los Alamos National Laboratory

    2009-01-01

    Positron emission backscatter imaging is a technique for interrogation and three-dimensional (3-D) reconstruction of hidden objects when we only have access to the objects from one side. Using time-of-flight differences in detected direct and backscattered positron-emitted photons, we construct 3-D images of target objects. Recently at Los Alamos National Laboratory, a fully three-dimensional imaging system has been built and the experimental results are discussed in this paper. Quantitative analysis of images reconstructed in both two- and three-dimensions are also presented.

  14. Experimental results and Monte Carlo simulations of a landmine localization device using the neutron backscattering method

    Energy Technology Data Exchange (ETDEWEB)

    Datema, C.P. E-mail: c.datema@iri.tudelft.nl; Bom, V.R.; Eijk, C.W.E. van

    2002-08-01

    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.

  15. 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.

  16. Monte-Carlo simulations of elastically backscattered neutrons from hidden explosives using three different neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    ElAgib, I. [College of Science, King Saud University, P.O. Box 2455 (Saudi Arabia)], E-mail: elagib@ksu.edu.sa; Elsheikh, N. [College of Applied and Industrial Science, University of Juba, Khartoum, P.O. Box 321 (Sudan); AlSewaidan, H. [College of Science, King Saud University, P.O. Box 2455 (Saudi Arabia); Habbani, F. [Faculty of Science, Physics Department, University of Khartoum, Khartoum, P.O. Box 321 (Sudan)

    2009-01-15

    Calculations of elastically backscattered (EBS) neutrons from hidden explosives buried in soil were performed using Monte-Carlo N-particle transport code MCNP5. Three different neutron sources were used in the study. The study re-examines the performance of the neutron backscattering methods in providing identification of hidden explosives through their chemical composition. The EBS neutron energy spectra of fast and slow neutrons of the major constituent elements in soil and an explosive material in form of TNT have shown definite structures that can be used for the identification of a buried landmine.

  17. Random matrix theory applied to acoustic backscattering and imaging in complex media.

    Science.gov (United States)

    Aubry, Alexandre; Derode, Arnaud

    2009-02-27

    The singular values distribution of the propagation operator in a random medium is investigated in a backscattering configuration. Experiments are carried out with pulsed ultrasonic waves around 3 MHz, using an array of transducers. Coherent backscattering and field correlations are taken into account. Interestingly, the distribution of singular values shows a dramatically different behavior in the single and multiple-scattering regimes. Based on a matrix separation of single and multiple-scattered waves, an experimental illustration of imaging through a highly scattering slab is presented.

  18. 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.

  19. Backscatter tolerant squeezed light source for advanced gravitational-wave detectors.

    Science.gov (United States)

    Chua, Sheon S Y; Stefszky, Michael S; Mow-Lowry, Conor M; Buchler, Ben C; Dwyer, Sheila; Shaddock, Daniel A; Lam, Ping Koy; McClelland, David E

    2011-12-01

    We report on the performance of a dual-wavelength resonant, traveling-wave optical parametric oscillator to generate squeezed light for application in advanced gravitational-wave interferometers. Shot noise suppression of 8.6±0.8 dB was measured across the detection band of interest to Advanced LIGO, and controlled squeezing measured over 5900 s. Our results also demonstrate that the traveling-wave design has excellent intracavity backscattered light suppression of 47 dB and incident backscattered light suppression of 41 dB, which is a crucial design issue for application in advanced interferometers.

  20. Statistical Properties of a Ring Laser with Injected Signal and Backscattering

    Institute of Scientific and Technical Information of China (English)

    LENG Feng; ZHU Shi-Qun

    2001-01-01

    The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements.Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light.``

  1. Coherent backscattering of inelastic photons from atoms and their mirror images

    CERN Document Server

    Moriya, P H; Teixeira, R Celistrino; Máximo, C E; Piovella, N; Bachelard, R; Kaiser, R; Courteille, Ph W

    2016-01-01

    Coherent backscattering is a coherence effect in the propagation of waves through disordered media involving two or more scattering events. Here, we report on the observation of coherent backscattering from individual atoms and their mirror images. This system displays two important advantages: First, the effect can be observed at low optical densities, which allows to work in very dilute clouds or far from resonance. Second, due to the fact that the radiation of an atom interferes constructively with that of its own image, the phenomenon is much more robust to dephasing induced by strong saturation. In particular, the contribution of inelastically scattered photons to the interference process is demonstrated.

  2. Influence of single scattering and multiple scattering on backscattered Mueller matrix in turbid media

    Institute of Scientific and Technical Information of China (English)

    Lanqing Xu; Hui Li; Yongping Zheng

    2009-01-01

    Monte Carlo algorithm and Stokes-Mueller formalism are used to simulate the propagation behavior of polarized light in turbid media. The influence of single scattering and multiple scattering on backscattered Mueller matrix in turbid media is discussed. Single and double scattering photons form the major part of backscattered polarization patterns, while multiple scattering photons present more likely as background. Further quantitative analyses show that single scattering approximation and double scattering approxima tion are quite accurate when discussing the polarization patterns near the incident point.

  3. Numerical Analysis of Ultrasound Backscattered Waves in Cancellous Bone Using a Finite-Difference Time-Domain Method: Isolation of the Backscattered Waves From Various Ranges of Bone Depths.

    Science.gov (United States)

    Hosokawa, Atsushi

    2015-06-01

    Using a finite-difference time-domain method, ultrasound backscattered waves inside cancellous bone were numerically analyzed to investigate the backscatter mechanism. Two bone models with different thicknesses were modeled with artificial absorbing layers positioned at the back surfaces of the model, and an ultrasound pulse wave was transmitted toward the front surface. By calculating the difference between the simulated waveforms obtained using the two bone models, the backscattered waves from a limited range of depths in cancellous bone could be isolated. The results showed that the fast and slow longitudinal waves, which have previously been observed only in the ultrasound waveform transmitted through the bone, could be distinguished in the backscattered waveform from a deeper bone depth when transmitting the ultrasound wave parallel to the main orientation of the trabecular network. The amplitudes of the fast and slow backscattered waves were more closely correlated with the bone porosity [R2 = 0.84 and 0.66 (p different times.

  4. Calibrated integrated backscatter and myocardial fibrosis in patients undergoing cardiac surgery

    NARCIS (Netherlands)

    Prior, David L; Somaratne, Jithendra B; Jenkins, Alicia J; Yii, Michael; Newcomb, Andrew E; Schalkwijk, Casper G; Black, Mary J; Kelly, Darren J; Campbell, Duncan J

    2015-01-01

    OBJECTIVE: The reported association between calibrated integrated backscatter (cIB) and myocardial fibrosis is based on study of patients with dilated or hypertrophic cardiomyopathy and extensive (mean 15-34%) fibrosis. Its association with lesser degrees of fibrosis is unknown. We examined the rela

  5. Dependence of {alpha}-particle backscattering on energy and source backing

    Energy Technology Data Exchange (ETDEWEB)

    Timon, A. Fernandez [ESCET, Universidad Rey Juan Carlos, C/ Tulipan s/n, 28933 Mostoles, Madrid (Spain)], E-mail: alfonso.fernandez@urjc.es; Vargas, M. Jurado [Departamento de Fisica, Universidad de Extremadura, Avda. Elvas s/n, 06071 Badajoz (Spain)

    2007-09-21

    Measurement of {alpha}-particle sources using 2{pi} counting detectors requires corrections for backscattering, and these depend on the material used as source backing and on the {alpha}-particle energy. This dependence has been analyzed theoretically by some authors, although assuming some simplifying approximations. In this work, we analyze the dependence of the backscattering coefficient B on energy and source backing, but by means of the Monte Carlo simulation code SRIM, thus avoiding the simplifying approximations assumed in the theoretical models. To study the dependence on the backing, we simulated {sup 210}Po point sources deposited on various backing materials with atomic numbers ranging from 4 to 79. The dependence on energy was studied by simulating {alpha}-particle point sources deposited on a platinum backing, with energies between 3 and 8 MeV. We found that the dependence of the backscattering coefficient B on {alpha}-particle energy and also on the mass number A of the backing approximately follows power function laws, in concordance with the theoretical models, although with exponents somewhat different from those established theoretically. In addition, although it was found that the scattering angle distribution is not Gaussian, our results confirm that there is a linear relationship between the backscattering coefficient B and the mean scattering angle {phi}, as suggested by the Crawford theory.

  6. 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...

  7. 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

    1987-01-01

    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

  8. On the optimum resolution of transmission-electron backscattered diffraction (t-EBSD)

    NARCIS (Netherlands)

    van Bremen, R.; Gomes, D. Ribas; de Jeer, L. T. H.; Ocelik, V.; De Hosson, J. Th. M.

    2016-01-01

    The work presented aims at determining the optimum physical resolution of the transmission-electron backscattered diffraction (t-EBSD) technique. The resolution depends critically on intrinsic factors such as the density, atomic number and thickness of the specimen but also on the extrinsic experime

  9. Processing ultrasound backscatter to monitor high-intensity focused ultrasound (HIFU) therapy

    Science.gov (United States)

    Kaczkowski, Peter J.; Anand, Ajay; Bailey, Michael R.

    2005-09-01

    The development of new noninvasive surgical methods such as HIFU for the treatment of cancer and internal bleeding requires simultaneous development of new sensing approaches to guide, monitor, and assess the therapy. Ultrasound imaging using echo amplitude has long been used to map tissue morphology for diagnostic interpretation by the clinician. New quantitative ultrasonic methods that rely on amplitude and phase processing for tissue characterization are being developed for monitoring of ablative therapy. We have been developing the use of full wave ultrasound backscattering for real-time temperature estimation, and to image changes in tissue backscatter spectrum as therapy progresses. Both approaches rely on differential processing of the backscatter signal in time, and precise measurement of phase differences. Noise and artifacts from motion and nonstationary speckle statistics are addressed by constraining inversions for tissue parameters with physical models. We present results of HIFU experiments with static point and scanned HIFU exposures in which temperature rise can be accurately mapped using a new heat transfer equation (HTE) model-constrained inverse approach. We also present results of a recently developed spectral imaging method that elucidates microbubble-mediated nonlinearity not visible as a change in backscatter amplitude. [Work supported by Army MRMC.

  10. Backscatter from ice growing on shallow tundra lakes near Barrow, Alaska, winter 1991-1992

    Science.gov (United States)

    Jeffries, M. O.; Wakabayashi, H.; Weeks, W. F.; Morris, K.

    1993-01-01

    The timing of freeze-up and break-up of Arctic lake ice is a potentially useful environmental indicator that could be monitored using SAR. In order to do this, it is important to understand how the properties and structure of the ice during its growth and decay affect radar backscatter and thus lake ice SAR signatures. The availability of radiometrically and geometrically calibrated digital SAR data time series from the Alaska SAR Facility has made it possible for the first time to quantify lake ice backscatter intensity (sigma(sup o)) variations. This has been done for ice growing on shallow tundra lakes near Barrow, NW Alaska, from initial growth in September 1991 until thawing and decay in June 1992. Field and laboratory observations and measurements of the lake ice were made in late April 1992. The field investigations of the coastal lakes near Barrow confirmed previous findings that, (1) ice frozen to the lake bottom had a dark signature in SAR images, indicating weak backscatter, while, (2) ice that was floating had a bright signature, indicating strong backscatter. At all sites, regardless of whether the ice was grounded or floating, there was a layer of clear, inclusion-free ice overlaying a layer of ice with dense concentrations of vertically oriented tubular bubbles. At some sites, there was a third layer of porous, snow-ice overlaying the clear ice.

  11. Flat ended steel wires, backscattering targets for calibrating over a large dynamic range

    NARCIS (Netherlands)

    Lubbers, Jaap; Graaff, Reindert

    2006-01-01

    A series of flat ended stainless steel wires was constructed and experimentally evaluated as point targets giving a calibrated backscattering over a large range (up to 72 dB) for ultrasound frequencies in the range 2 to 10 MHz. Over a range of 36 dB, theory was strictly followed (within 1 dB), givin

  12. A MONTE CARLO SIMULATION OF SECONDARY ELECTRON AND BACKSCATTERED ELECTRON IMAGES IN SCANNING ELECTRON MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    H.M. Li; Z.J. Ding

    2005-01-01

    A new parallel Monte Carlo simulation method of secondary electron (SE) and backscattered electron images (BSE) of scanning electron microscopy (SEM) for a complex geometric structure has been developed. This paper describes briefly the simulation method and the modification to the conventional sampling method for the step length. Example simulation results have been obtained for several artificial structures.

  13. 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...

  14. Multi-parameter optimization of a neutron backscattering landmine detection system.

    Science.gov (United States)

    Metwally, Walid A

    2015-11-01

    A study was performed to enhance the neutron moderation and investigate the response of a landmine detection system based on measuring backscattered neutrons with a (3)He detector. Parameters affecting the system's response were simultaneously optimized to improve the sensitivity of the detection system. The optimized sensitivity of the detection system was analyzed for different horizontal and lateral positions of a landmine.

  15. Characterization of highly scattering media by measurement of diffusely backscattered polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Hielscher, A.H.; Mourant, J.R.; Bigio, I.J.

    2000-01-04

    An apparatus and method for recording spatially dependent intensity patterns of polarized light that is diffusely backscattered from highly scattering media are described. These intensity patterns can be used to differentiate different turbid media, such as polystyrene-sphere and biological-cell suspensions. Polarized light from a He-Ne laser ({lambda} = 543 nm) is focused onto the surface of the scattering medium, and a surface area of approximately 4 x 4 cm centered on the light input point is imaged through polarization analysis optics onto a CCD camera. A variety of intensity patterns may be observed by varying the polarization state of the incident laser light and changing the analyzer configuration to detect different polarization components of the backscattered light. Experimental results for polystyrene-sphere and intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, size, and anisotropy factor, g, of the particles constituting the scattering medium. Measurements performed on biological cell suspensions show that intensity patterns can be used to differentiate between suspensions of cancerous and non-cancerous cells. Introduction of the Mueller-matrix for diffusely backscattered light, permits the selection of a subset of measurements which comprehensively describes the optical properties of backscattering media.

  16. Characterization of highly scattering media by measurement of diffusely backscattered polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Hielscher, Andreas H. (Brooklyn, NY); Mourant, Judith R. (Los Alamos, NM); Bigio, Irving J. (Los Alamos, NM)

    2000-01-01

    An apparatus and method for recording spatially dependent intensity patterns of polarized light that is diffusely backscattered from highly scattering media are described. These intensity patterns can be used to differentiate different turbid media, such as polystyrene-sphere and biological-cell suspensions. Polarized light from a He-Ne laser (.lambda.=543 nm) is focused onto the surface of the scattering medium, and a surface area of approximately 4.times.4 cm centered on the light input point is imaged through polarization analysis optics onto a CCD camera. A variety of intensity patterns may be observed by varying the polarization state of the incident laser light and changing the analyzer configuration to detect different polarization components of the backscattered light. Experimental results for polystyrene-sphere and Intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, size, and anisotropy factor, g, of the particles constituting the scattering medium. Measurements performed on biological cell suspensions show that intensity patterns can be used to differentiate between suspensions of cancerous and non-cancerous cells. Introduction of the Mueller-matrix for diffusely backscattered light, permits the selection of a subset of measurements which comprehensively describes the optical properties of backscattering media.

  17. Bathymetry, acoustic backscatter, and seafloor character of Farallon Escarpment and Rittenburg Bank, northern California

    Science.gov (United States)

    Dartnell, Peter; Cochrane, Guy R.; Finlayson, David P.

    2014-01-01

    In 2011, scientists from the U.S. Geological Survey’s Coastal and Marine Geology Program acquired bathymetry and acoustic-backscatter data along the upper slope of the Farallon Escarpment and Rittenburg Bank within the Gulf of the Farallones National Marine Sanctuary offshore of the San Francisco Bay area. The surveys were funded by the National Oceanic and Atmospheric Administration’s Deep Sea Coral Research and Technology Program to identify potential deep sea coral habitat prior to planned sampling efforts. Bathymetry and acoustic-backscatter data can be used to map seafloor geology (rock, sand, mud), and slope of the sea floor, both of which are useful for the prediction of deep sea coral habitat. The data also can be used for the prediction of sediment and contaminant budgets and transport, and for the assessment of earthquake and tsunami hazards. The surveys were conducted aboard National Oceanic and Atmospheric Administration’s National Marine Sanctuary Program’s 67-foot-long research vessel Fulmar outfitted with a U.S. Geological Survey 100-kHz Reson 7111 multibeam-echosounder system. This report provides the bathymetry and backscatter data acquired during these surveys, interpretive seafloor character maps in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee metadata.

  18. 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...

  19. Retrieval of aerosol backscatter and extinction from airborne coherent Doppler wind lidar measurements

    Directory of Open Access Journals (Sweden)

    F. Chouza

    2015-02-01

    Full Text Available A novel method for calibration and quantitative aerosol optical properties retrieval from Doppler wind lidars (DWL is presented in this work. Due to the strong wavelength dependence of the atmospheric molecular backscatter and the low sensitivity of the coherent detection to spectrally broad signals, calibration methods for aerosol lidars cannot be applied to a coherent DWLs usually operating at wavelengths between 1.5–2 μm. Instead, concurrent measurements of an airborne DWL at 2 μm and the POLIS ground-based aerosol lidar at 532 nm are used in this work, in combination with sun photometer measurements, for the calibration and retrieval of aerosol backscatter and extinction profiles. The proposed method was applied to measurements from the SALTRACE experiment in June–July 2013, which aimed at quantifying the aerosol transport and change in aerosol properties from the Sahara desert to the Caribbean. The retrieved backscatter and extinction coefficient profiles from the airborne DWL are within 20% of POLIS aerosol lidar and CALIPSO satellite measurements. Thus the proposed method extends the capabilities of coherent DWL to measure profiles of the horizontal and vertical wind towards aerosol backscatter and extinction profiles, which is of high benefit for aerosol transport studies.

  20. Ultrasound characterization of arterial wall structures based on integrated backscatter profiles

    Science.gov (United States)

    Pedersen, Peder C.; Chakareski, Jacob; Lara-Montalvo, Ruben

    2003-05-01

    Studies suggest that the composition of atherosclerotic plaque in the carotid arteries is predictive of stroke risk. The goal of this investigation has been to explore how well the true integrated backscatter (IBS) from plaque regions can be measured non-invasively using ultrasound, based on which plaque composition may be inferred. To obtain the true arterial IBS non-invasively, the scattering and aberrating effect of the intervening tissue layers must be overcome. This is achieved by using the IBS from arterial blood as a reference backscatter, specifically the backscatter from a blood volume along the same scan line as and adjacent to the region of interest. The arterial blood IBS is obtained as an estimated mean of a stochastic process, after clutter removal. We have shown that the variance of the IBS estimate of the blood backscatter signal can be quantified and reduced to a tolerable level. The results are in the form of IBS profiles along the vessel. IBS profiles not normalized with the IBS of the blood-mimicking fluid have been measured for vessels phantom, with and without an intervening inhomogeneous medium; these results are contrasted with the corresponding normalized IBS profiles.

  1. 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.

  2. Energy Filtering and Coaxial Detection of the Backscattered Electrons in Scanning Electron Microscope

    Institute of Scientific and Technical Information of China (English)

    JIANG Chang-Zhong; P. Morin; N. Rosenberg

    2000-01-01

    A new detection system in scanning electron microscope, which filters in energy and detects the backscattered electrons close to the microscope axis, is described. This technique ameliorates the dependence of the back. scat tering coefficient on atomic number, and suppresses effectively the relief contrast at the same time. Therefore this new method is very suitable to the composition analysis.

  3. 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...

  4. On the backscatter of solar He II, 304 A radiation from interplanetary He/+/.

    Science.gov (United States)

    Paresce, F.; Bowyer, S.

    1973-01-01

    Backscatter of solar He II, 304 A radiation by interplanetary positive helium ions is shown to be insufficient to account for recent observations of this airglow radiation in the night sky at rocket altitudes. In fact, for most viewing directions, the expected intensities probably fall well below the sensitivity threshold of existing extreme ultraviolet instrumentation.

  5. Multi-beam backscatter data to characterize the mound and channel provinces of the Porcupine Seabight - northeast Atlantic margin

    Science.gov (United States)

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

    2003-04-01

    Large scale oceanographic explorations are presently continuing around the Porcupine Seabight area, which is located towards the south-west Ireland. This area is an embayment of the north Atlantic continental margins. It's importance due to the dominant hydrocarbon resources are not unknown, and on-going experiments are important due to the involvement of higher order variability (in terms of physical and geological settings) around this area. Multi-beam angular backscatter study to characterize the eastern slope seafloor of the Porcupine Seabight is initiated first time. Backscatter data acquired from twenty-nine locations of the carbonate mounds and associated buried mounds (Belgica province), and channel seafloors like: Kings channel and Gollum channels are analysed in this paper. Processing details of the angular backscatter data was carried out to apply the scattering models to determine seafloor roughness. Employed normalization to the angular backscatter data to obtain shape invariant seafloor indicate distinct grey levels for mound, buried mound, and various channel seafloors (four distinct types of seafloors) within the backscatter dynamic range of 12 dB. The backscatter levels are the highest for the mound areas followed by the buried mounds, channel seafloor, and inter-channel areas. Present study was further substantiated by employing a semi-empirical method to determine the shape aspects of the area backscatter strengths. Estimated three parameters like: predicted 20 degree angular backscatter response, slope and coefficient of variations of the angular backscatter responses are computed to understand general seafloor characteristics of the varying area seafloor. The use of Helmholtz-Kirchhoff's angular backscatter theory which is a functional of the power law are carried out to estimate sea water floor interface roughness parameters. The sediment volume inhomogeneity parameters are also determined by use of curve fitting to the overlaying interface

  6. 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

  7. Shallow water acoustic backscatter and reverberation measurements using a 68-kHz cylindrical array

    Science.gov (United States)

    Gallaudet, Timothy Cole

    2001-10-01

    The characterization of high frequency, shallow water acoustic backscatter and reverberation is important because acoustic systems are used in many scientific, commercial, and military applications. The approach taken is to use data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz multibeam sonar capable of 360° imaging in a vertical plane perpendicular to its direction of travel. With this unique capability, acoustic backscatter imagery of the seafloor, sea surface, and horizontal and vertical planes in the volume are constructed from data obtained in 200m deep waters in the Northeastern Gulf of Mexico when the TVSS was towed 78m below the surface, 735m astern of a towship. The processed imagery provide a quasi-synoptic characterization of the spatial and temporal structure of boundary and volume acoustic backscatter and reverberation. Diffraction, element patterns, and high sidelobe levels are shown to be the most serious problems affecting cylindrical arrays such as the TVSS, and an amplitude shading method is presented for reducing the peak sidelobe levels of irregular-line and non-coplanar arrays. Errors in the towfish's attitude and motion sensor, and irregularities in the TVSS's transmitted beampattern produce artifacts in the TVSS-derived bathymetry and seafloor acoustic backscatter imagery. Correction strategies for these problems are described, which are unique in that they use environmental information extracted from both ocean boundaries. Sea surface and volume acoustic backscatter imagery are used to explore and characterize the structure of near-surface bubble clouds, schooling fish, and zooplankton. The simultaneous horizontal and vertical coverage provided by the TVSS is shown to be a primary advantage, motivating further use of multibeam sonars in these applications. Whereas boundary backscatter fluctuations are well described by Weibull, K, and Rayleigh mixture probability distributions, those corresponding to volume backscatter are

  8. Backscattered Acoustic Energy by Monobubbles Experimental Approach and Statistical Study of the Attenuation

    Directory of Open Access Journals (Sweden)

    Ali Khelil

    2009-01-01

    Full Text Available Problem statement: As the number of air bubbles in the sea is very high, they are so many acoustic diffusers who make illegible the recordings the purpose of which is to quantify the alive bodies. The signals backscattered by air bubbles constitute a parasite in offshore recordings and must be eliminated. It is planned to finalize techniques allowing the localization and the identification of a signal backscattered by an air bubble. Once this type of signal was localized and identified on an offshore recording, it is easy to eliminate it. From then, we could have recordings where the only diffusers would be alive bodies like the zooplankton. Approach: We began a work of characterization of signals of bubbles to discriminate between them and those backscattered by alive diffusers. We realized in laboratory a bench test then we finalized an original method of production of air bubbles with known size in a liquid medium. Five types of monobubbles were generated in a water column by a technique using a peristaltic pump. This technique allowed obtaining a continuous water flow carrying same-sized air bubble. The bubbles radii were calculated from the measure of rise limit speed. The acoustic responses of these bubbles (to a frequent wide bandwidth ultrasonic wave were studied by statistical methods in order to determine the variation of the energy backscattered by a calibrated bubble according to its depth. Results: Besides the production technique of calibrated bulles that was finalized, we established that the variation of backscattered energy according to depth can be explained by simple exponential models which permitted to estimate the constant of absorption. Conclusion: The coming step will be to correct the signal of the effect of the absorption of energy by the middle, then to elaborate a protocol of localization of the signals of bubbles on recordings where multiple diffusers appear. The results had to be refined and adapted for in

  9. Ceilometer-lidar inter-comparison: backscatter coefficient retrieval and signal-to-noise ratio determination

    Directory of Open Access Journals (Sweden)

    B. Heese

    2010-08-01

    Full Text Available The potential of a new generation of ceilometer instruments for aerosol monitoring has been studied in the Ceilometer-Lidar Inter- Comparison (CLIC study. The ceilometer is of type CHM15k from Jenoptik, Germany, which uses a solid state laser at the wavelength of 1064 nm and an avalanche photodiode for photon counting detection. The German Meteorological Service is in progress of setting up a ceilometer network for aerosol monitoring in Germany. The intercomparison study was performed to determine whether the ceilometers are capable to deliver quality assured particle backscatter coefficient profiles. For this, the derived ceilometer profiles were compared to simultaneously measured lidar profiles at the same wavelength. The lidar used for this intercomparison was IfTs multi-wavelengths Raman lidar PollyXT. During the EARLINET lidar intercomparison campaign EARLI 09 in Leipzig, Germany, a new type of the Jenoptik ceilometer, the CHM15k-X, took part. This new ceilometer has a new optical setup resulting in a complete overlap at 150 m. The derived particle backscatter profiles were compared to profiles derived from PollyXTs measurements, too. The elastic daytime particle backscatter profiles as well as the less noisy night-time Raman particle backscatter profiles compare well with the ceilometers profiles in atmospheric structures like aerosol layers or the boundary layer top height. The calibration of the ceilometer profiles by an independent measurement of the aerosol optical depth (AOD by a sun photometer is necessary to determine the correct magnitude of the particle backscatter coefficient profiles. A comprehensive signal-to-noise ratio study was carried out to characterize the ceilometers signal performance with increasing altitude.

  10. 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.

  11. Variations in Optical Scattering and Backscattering by Organic and Inorganic Particulates in Chinese Lakes of Taihu, Chaohu and Dianchi

    Institute of Scientific and Technical Information of China (English)

    LYU Heng; WANG Qiao; WU Chuanqing; ZHU Li; LI Yunmei; HUANG Jiazhu

    2015-01-01

    This stu dy presents an investigation of the scattering and backscattering properties of the particulates in three Chinese inlandlakes (the Taihu Lake,the Chaohu Lake and the Dianchi Lake) based on in situ measurements taken at 119 sites.We modeled the particulate scattering spectra using a wavelength-dependent power-law function,finding that the power-law exponents in the Taihu Lake and the Chaohu Lake differ from those in the Dianchi Lake but are similar to the values in the U.S.coastal waters.In contrast to the open ocean,the backscattering properties in the three lakes can not be determined only from chlorophyll-a concentration.The backscattering ratio spectra exhibit a wavelength dependence feature in all three lakes,generally decreasing with the increasing wavelength.Analysis results of the correlations between the backscattering ratio and the individual water quality parameters clearly show that there are distinctive relations among the three lakes,attributed primarily to different compositions of optically active materials in the three lakes.Analysis of the mass-specific scattering and backscattering coefficients shows that the coefficients at wavelength 532 nm in the Taihu Lake and Chaohu Lake are similar,but they are apparently different from those in the Dianehi Lake.Lastly,Model I multiple linear regressions were adopted to partition the mass-specific cross-sections for scattering and backscattering into organic and inorganic cross-sections to further interpret the scattering and backscattering properties.The relative contribution of organic and inorganic particulates to scattering and backscattering is clearly different among the three lakes.The scattering and backscattering properties of the particulates in the three inland lakes vary significantly based on our collected data.The results indicated that the existing semi-analytical water quality retrieval models of the Taihu Lake can not be applied perfectly to the Chaohu Lake and the Dianchi Lake.

  12. Assessment of blood coagulation under various flow conditions with ultrasound backscattering.

    Science.gov (United States)

    Huang, Chih-Chung; Wang, Shyh-Hau

    2007-12-01

    Several in vitro studies have employed ultrasonic techniques to detect varying properties of coagulating blood under static or stirred conditions. Most of those studies mainly addressed on the development and feasibility of modalities and however were not fully considering the effect of blood flow. To better elucidate this issue, ultrasonic backscattering were measured from the coagulating porcine blood circulated in a mock flow loop with various steady laminar flows at mean shear rates from 10 to 100 s(-1). A 3 ml of 0.5 M CaCl2 solution for inducing blood coagulation was added to that of 30 ml blood circulated in the conduit. For each measurement carried out with a 10-MHz transducer, backscattered signals digitized at 100-MHz sampling frequency were acquired for a total of 20 min at temporal resolution of 50 A-lines per s. The integrated backscatter (IB) was calculated for assessing backscattering properties of coagulating blood. The results show that blood coagulation tended to be increased corresponding to the addition of CaCl2 solution: the IB was increased approximately 6.1 +/- 0.6 (mean +/- standard deviation), 5.4 +/- 0.9, and 4.5 +/- 1.2 dB at 310 +/- 62, 420 +/- 88, and 610 +/- 102 s associated with mean shear rates of 10, 40, and 100 s(-1), respectively. The rate of increasing IB for evaluating the growth of clot was estimated to be 0.075 +/- 0.017, 0.052 +/- 0.027, and 0.038 +/- 0.012 delta dB delta s(-1) corresponding to the increase of mean shear rates. These results consistently demonstrate that higher shear rate tends to prolong the duration for the flowing blood to be coagulated and to decrease the rate of IB. Moreover, the laminar flow was changed to turbulent flow during that the blood was clotting discerned by spatial variations of ultrasound backscattering in the conduit. All these results validate that ultrasound backscattering is feasible to be utilized for detecting and assessing blood coagulation under dynamic conditions.

  13. Analysis of Kikuchi band contrast reversal in electron backscatter diffraction patterns of silicon.

    Science.gov (United States)

    Winkelmann, Aimo; Nolze, Gert

    2010-02-01

    We analyze the contrast reversal of Kikuchi bands that can be seen in electron backscatter diffraction (EBSD) patterns under specific experimental conditions. The observed effect can be reproduced using dynamical electron diffraction calculations. Two crucial contributions are identified to be at work: First, the incident beam creates a depth distribution of incoherently backscattered electrons which depends on the incidence angle of the beam. Second, the localized inelastic scattering in the outgoing path leads to pronounced anomalous absorption effects for electrons at grazing emission angles, as these electrons have to go through the largest amount of material. We use simple model depth distributions to account for the incident beam effect, and we assume an exit angle dependent effective crystal thickness in the dynamical electron diffraction calculations. Very good agreement is obtained with experimental observations for silicon at 20keV primary beam energy.

  14. Sensitivity improvement of a laser interferometer limited by inelastic back-scattering, employing dual readout

    CERN Document Server

    Meinders, Melanie

    2015-01-01

    Inelastic back-scattering of stray light is a long-standing problem in high-sensitivity interferometric measurements and a potential limitation for advanced gravitational-wave detectors, in particular at sub-audio-band frequencies. The emerging parasitic interferences cannot be distinguished from a scientific signal via conventional single readout. In this work, we propose and demonstrate the subtraction of inelastic back-scatter signals by employing dual homodyne detection on the output light -- here -- of a table-top Michelson interferometer. The additional readout contains solely parasitic signals and is used to model the scatter source. Subtraction of the scatter signal reduces the noise spectral density and thus improves the measurement sensitivity. Our scheme is qualitatively different from the previously demonstrated vetoing of scatter signals and opens a new path for improving the sensitivity of future gravitational-wave detectors.

  15. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Energy Technology Data Exchange (ETDEWEB)

    Sedao, Xxx, E-mail: sedao.xxx@gmail.com [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Maurice, Claire [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Quey, Romain; Blanc, Gilles [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Pigeon, Florent [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France)

    2014-05-01

    Graphical abstract: -- Highlight: •Lattice rotation and its distribution in laser-induced periodic surface structures (LIPSS) and the subsurface region on a nickel substrate are revealed using electron backscatter diffraction (EBSD). -- Abstract: We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1–3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  16. Direct solution of the backscatter equation for ABS instruments through a Riccati reformulation

    Science.gov (United States)

    Hamilton, L. J.; Hall, M. V.

    2012-09-01

    Measurements of suspended sediment concentration profiles in aquatic environments may be made by remote sensing acoustic backscatter (ABS) instruments. These typically operate at MHz frequencies and narrow beamwidths (1-2°). The backscatter equation for these instruments is not in a closed form. It may be solved by iteration. A direct general solution has previously been presented by recasting into the form of a Bernoulli equation [Thosteson, E.D., Hanes, D.M., 1998. Journal of the Acoustical Society of America 104 (2), 820-830 (Pt. 1)]. It is shown that the direct solution is also enabled by recasting as a Riccati equation. The direct solution obtained by the Riccati formulation has the same form as given previously, but its derivation clarifies inconsistencies in previous work which have disguised its potential usefulness.

  17. AN ANALYSIS OF THE MICROSTRUCTURE CHARACTERISTICS IN HUMAN KIDNEY WITH ULTRASONIC BACKSCATTERING

    Institute of Scientific and Technical Information of China (English)

    Yan Bige; Ta Dean; Wang Rong

    2005-01-01

    Objective To investigate the microstructure characteristics in human kidney with the WD cepstrum of ultrasonic backscattering. Methods By using this method, an analysis of the backscattering signals of normal and pathological human kidney in vitro was made and the mean spacing of the scatterers of biological soft tissues was estimated, then compared the means of this new approach with the means of the AR cepstrum. Results The results show that the mean spacings of the scatterers of the two different kidney tissues are noticeably different, which reveals the fact that the WD cepstrum works more effective than the AR cepstrum in showing the features of the microstructure of soft tissues. Conclusion The WD cepstrum is an effective mean to analyze the ultrasonic scattering signals and determine the features of the mean spacing of the scatterers of soft tissues. This method provides more available clinical diagnosis and improves the results of mean spacing of the scatterers of soft tissues.

  18. Dependence of diffuse ultrasonic backscatter on residual stress in 1080 steel.

    Science.gov (United States)

    Du, Hualong; Turner, Joseph A

    2016-04-01

    In this article, the effects of residual stress on the ultrasonic scattering in a quenched steel sample are investigated by calculating the change of spatial variance amplitudes of ultrasonic signals after removing residual stress via annealing. The experimental results show that the average spatial variance amplitude decreases by about 11.89% for a scan area on the quenched surface after removing residual stress. This quantity was used to estimate the residual stress based on the developed stress-dependent backscatter model. In addition, the residual stress on the whole scan area was mapped by calculating the change of the spatial variance amplitude for each subarea after annealing, respectively. Diffuse ultrasonic backscatter signals show a high sensitivity to residual stress such that this technique has potential as a non-destructive method for measuring residual stress.

  19. 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.

  20. 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

  1. Acoustical and optical backscatter measurements of sediment transport in the 1988 1989 STRESS experiment

    Science.gov (United States)

    Lynch, J. F.; Gross, T. F.; Sherwood, C. R.; Irish, J. D.; Brumley, B. H.

    1997-04-01

    During the 1988-1989 Sediment Transport Events on Shelves and Slopes (STRESS) experiment, a 1-MHz acoustic backscatter system (ABSS), deployed in 90 m of water off the California coast measured vertical profiles of suspended sediment concentration from 1.5 to (nominally) 26 meters above bottom (m.a.b.). An 8-week-long time series was obtained, showing major sediment transport events (storms) in late December and early January. Comparison of the acoustics measurements from 1.5 m.a.b. are made with optical backscatter system (OBS) concentration estimates lower in the boundary layer (0.25 m.a.b.). Correlations between ABSS and OBS concentration measurements and the boundary layer forcing functions (waves, currents, and their non-linear interaction) provided a variety of insights into the nature of the sediment transport of the STRESS site. Transport rates and integrated transport are seen to be dominated by the largest storm events.

  2. Measurements of aerosol distribution by an elastic-backscatter lidar in summer 2008 in Beijing

    Institute of Scientific and Technical Information of China (English)

    Zhenyi Chen; Wenqing Liu; Yujun Zhang; Nanjing Zhao; Junfeng He; Jun Ruan

    2009-01-01

    Elastic lidar observations of profiles of the aerosol extinction,backscattering coefficients,and the lidar ratio have been performed in Beijing.The elastic lidar transmitts wavelengths of 532 and 355 nm.The measurement altitude can reach up to 6 km.The similarity of the extinction and backscattering profiles suggests a close relation between the mean transmission and reflection properties.The lidar ratio on July 22,2008 varied from 10 to 30 sr with the mean value of 20 sr.The profiles of the aerosol properties indicate the cirrus at 6-km altitude and a well-mixed boundary layer from July 22 to 24,2008.The detected boundary layer also agrees well with the high and stable ozone concentration obtained from the differential optical absorption spectroscopy(DOAS)system.

  3. A Field Method for Backscatter Calibration Applied to NOAA's Reson 7125 Multibeam Echo-Sounders

    Science.gov (United States)

    Welton, Briana

    Acoustic seafloor backscatter measurements made by multiple Reson multibeam echo-sounders (MBES) used for hydrographic survey are observed to be inconsistent, affecting the quality of data products and impeding large-scale processing efforts. A method to conduct a relative inter and intea sonar calibration in the field using dual frequency Reson 7125 MBES has been developed, tested, and evaluated to improve the consistency of backscatter measurements made from multiple MBES systems. The approach is unique in that it determines a set of corrections for power, gain, pulse length, and an angle dependent calibration term relative to a single Reson 7125 MBES calibrated in an acoustic test tank. These corrections for each MBES can then be applied during processing for any acquisition setting combination. This approach seeks to reduce the need for subjective and inefficient manual data or data product manipulation during post processing, providing a foundation for improved automated seafloor characterization using data from more than one MBES system.

  4. 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.

  5. A Synthetic Aperture System Based on Backscattering Signals of Compass Navigation Satellite: Concept and Feasibility

    Directory of Open Access Journals (Sweden)

    Wang Hai-yang

    2012-06-01

    Full Text Available A concept of a bi-static geosynchronous synthetic aperture system, which is formed by reusing backscattered signals of Compass Navigation Satellite System (CNSS, is proposed. The geometric relations of a geostationary satellite of CNSS, located on a geosynchronous satellite receiver, which is illuminated by the backscattered energy of a satellite of CNSS, and a ground station is built up, and following the relations as well as principle of synthetic aperture radar, we expatiate the feasibility of the system by considering parameters such as imaging resolution, ratio of signal to noise and link budget, etc.. Besides, the potential remote sensing applications for measurement of terrain humidity, characteristics of space-time dynamics of changing of terrain surface and atmospheric characteristic, etc..

  6. 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.

  7. Quantitative Test of the Evolution of Geant4 Electron Backscattering Simulation

    CERN Document Server

    Basaglia, Tullio; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Sung Hun; Pia, Maria Grazia; Saracco, Paolo

    2016-01-01

    Evolutions of Geant4 code have affected the simulation of electron backscattering with respect to previously published results. Their effects are quantified by analyzing the compatibility of the simulated electron backscattering fraction with a large collection of experimental data for a wide set of physics configuration options available in Geant4. Special emphasis is placed on two electron scattering implementations first released in Geant4 version 10.2: the Goudsmit-Saunderson multiple scattering model and a single Coulomb scattering model based on Mott cross section calculation. The new Goudsmit-Saunderson multiple scattering model appears to perform equally or less accurately than the model implemented in previous Geant4 versions, depending on the electron energy. The new Coulomb scattering model was flawed from a physics point of view, but computationally fast in Geant4 version 10.2; the physics correction released in Geant4 version 10.2p01 severely degrades its computational performance. Evolutions in ...

  8. On the formation mechanisms, spatial resolution and intensity of backscatter Kikuchi patterns.

    Science.gov (United States)

    Zaefferer, S

    2007-01-01

    The present paper is divided into two main sections. In the first, the formation mechanisms of backscatter Kikuchi patterns (BKP) are discussed on the basis of measurements on the sharpness of Kikuchi lines and on the spatial, that means the lateral and depth resolution of the technique. We propose that thermal diffuse scattering is the important incoherent scattering mechanism involved in pattern formation. This mechanism is not considered in the classical description of the origin of backscattered electrons in the scanning electron microscope (SEM) which is why there is in some important points no agreement between classical Monte-Carlo-type electron trajectory simulations and experimental results. We assume that the energy spectrum of the backscattered electrons shows, similar to the spectra in transmission electron microscopy, a sharp zero-loss peak. In the second section, we discuss the intensity of Kikuchi bands in BKP. It is shown that the kinematical theory gives-of course-not the correct intensities, but that these intensities are, on the other hand, not too far off the experimental ones. We subsequently introduce a simple intensity correction procedure that is based on the two-beam dynamical theory, originally proposed by Blackman for transmission electron diffraction patterns. It is shown by examples of diffraction patterns of niobium and silicon that this procedure leads to satisfying results, once two unknown variables (a universal constant and the exit depth of the electrons) have been empirically fit. It is assumed that in the future, this correction will improve the possibilities of phase identification by backscatter Kikuchi diffraction patterns.

  9. Distributed temperature monitoring for liquid sodium leakage detection using OFDR-based Rayleigh backscattering

    Science.gov (United States)

    Boldyreva, E.; Cotillard, R.; Laffont, G.; Ferdinand, P.; Cambet, D.; Jeannot, J.-P.; Charvet, P.; Albaladéjo, S.; Rodriguez, G.

    2014-05-01

    For the first time, a gold coated single mode optical fiber has been used to detect a liquid sodium leakage on a pipe of secondary circuit pipe mock-up of nuclear fast reactor (Gen IV) by means of Optical Frequency Domain Reflectometry-based on Rayleigh backscattering. During 150 min of the experiment we were able to detect and monitor the evolution of a liquid sodium leakage on the surface of the pipe.

  10. Investigation of the solid-state reaction between nickel oxide and alumina by Rutherford backscattering (RBS)

    NARCIS (Netherlands)

    Roos, G. de; Geus, John W.; Fluit, J.M.; Wit, J.H. de

    1980-01-01

    The reaction of NiO and Al2O3 to form NiAl2O4 was investigated by means of Rutherford backscattering of 3 MeV He+-ions. The NiO was obtained by oxidation at 900°C of a nickel film vapour-deposited onto alumina substrates. The reaction of NiO and Al2O3 did not proceed markedly at 900°C. The reaction

  11. Sensitivity of L-Band SAR Backscatter to Aboveground Biomass of Global Forests

    Directory of Open Access Journals (Sweden)

    Yifan Yu

    2016-06-01

    Full Text Available Synthetic Aperture Radar (SAR backscatter measurements are sensitive to forest aboveground biomass (AGB, and the observations from space can be used for mapping AGB globally. However, the radar sensitivity saturates at higher AGB values depending on the wavelength and geometry of radar measurements, and is influenced by the structure of the forest and environmental conditions. Here, we examine the sensitivity of SAR at the L-band frequency (~25 cm wavelength to AGB in order to examine the performance of future joint National Aeronautics and Space Administration, Indian Space Research Organisation NASA-ISRO SAR mission in mapping the AGB of global forests. For SAR data, we use the Phased Array L-Band SAR (PALSAR backscatter from the Advanced Land Observing Satellite (ALOS aggregated at a 100-m spatial resolution; and for AGB data, we use more than three million AGB values derived from the Geoscience Laser Altimeter System (GLAS LiDAR height metrics at about 0.16–0.25 ha footprints across eleven different forest types globally. The results from statistical analysis show that, over all eleven forest types, saturation level of L-band radar at HV polarization on average remains ≥100 Mg·ha−1. Fresh water swamp forests have the lowest saturation with AGB at ~80 Mg·ha−1, while needleleaf forests have the highest saturation at ~250 Mg·ha−1. Swamp forests show a strong backscatter from the vegetation-surface specular reflection due to inundation that requires to be treated separately from those on terra firme. Our results demonstrate that L-Band backscatter relations to AGB can be significantly different depending on forest types and environmental effects, requiring multiple algorithms to map AGB from time series of satellite radar observations globally.

  12. Ultrasonic tissue characterization with integrated backscatter. Acute myocardial ischemia, reperfusion, and stunned myocardium in patients

    Energy Technology Data Exchange (ETDEWEB)

    Milunski, M.R.; Mohr, G.A.; Perez, J.E.; Vered, Z.; Wear, K.A.; Gessler, C.J.; Sobel, B.E.; Miller, J.G.; Wickline, S.A. (Washington Univ., St. Louis, MO (USA))

    1989-09-01

    We have previously shown in studies of experimental animals that myocardium exhibits a cardiac cycle-dependent variation of integrated backscatter that reflects regional myocardial contractile performance and that is blunted promptly after arterial occlusion and recovers after reperfusion. To define the clinical utility of ultrasonic tissue characterization with integrated backscatter for detection of acute myocardial infarction and reperfusion, 21 patients (14 men and seven women) were studied in the cardiac care unit within the first 24 hours (mean time, 11.3 hours; range, 3.5-23.8 hours) after the onset of symptoms indicative of acute myocardial infarction with conventional two-dimensional and M-mode echocardiography and with analysis of integrated backscatter. The magnitude of cyclic variation of integrated backscatter was measured from several sites within acute infarct regions and normal regions remote from the infarct zone for each patient. The average magnitude of cyclic variation among all patients (n = 21) was 4.8 +/- 0.5 dB in normal regions compared with 0.8 +/- 0.3 dB in infarct regions (p less than 0.05) within the first 24 hours after the onset of symptoms. Among the patients who had two studies, 15 (mean, 7.1 days; range, 2-31 days for second study) underwent coronary arteriography to define vessel patency. In patients with vessels with documented patency (n = 10), the magnitude of cyclic variation in infarct regions increased over time from 1.3 +/- 0.6 to 2.5 +/- 0.5 dB from the initial to final study (p less than 0.05). Patients with occluded infarct-related arteries (n = 5) exhibited no significant recovery of cyclic variation (0.3 +/- 0.3-0.6 +/- 0.3 dB). A blinded analysis of standard two-dimensional echocardiographic images revealed no significant recovery of wall thickening in either group over the same time intervals.

  13. SPHERES, Jülich's high-flux neutron backscattering spectrometer at FRM II.

    Science.gov (United States)

    Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kämmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J; Schneider, Harald; Staringer, Simon

    2012-07-01

    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ± 31 μeV, and a signal-to-noise ratio of up to 1750:1.

  14. SPHERES, J\\"ulich's High-Flux Neutron Backscattering Spectrometer at FRM II

    CERN Document Server

    Wuttke, Joachim; Drochner, Matthias; Kämmerling, Hans; Kayser, Franz-Joseph; Pardo, Luis Carlos; Prager, Michael; Ossovyi, Vladimir; Schneider, Gerald J; Schneider, Harald; Staringer, Simon; Richter, Dieter

    2012-01-01

    SPHERES (SPectrometer with High Energy RESolution) is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the J\\"ulich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 micro-eV, a dynamic range of +-31 micro-eV, and a signal-to-noise ratio of up to 1750:1.

  15. SPHERES, Juelich's high-flux neutron backscattering spectrometer at FRM II

    Energy Technology Data Exchange (ETDEWEB)

    Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kaemmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J.; Schneider, Harald; Staringer, Simon [Forschungszentrum Juelich GmbH, 52425 Juelich (Germany)

    2012-07-15

    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 {mu}eV, a dynamic range of {+-} 31 {mu}eV, and a signal-to-noise ratio of up to 1750:1.

  16. The status of the Delft University Neutron Backscatter Landmine Detector (DUNBLAD).

    Science.gov (United States)

    Bom, V R; Datema, C P; van Eijk, C W E

    2004-07-01

    The neutron backscattering technique may be applied to search for non-metallic landmines in relatively dry soils. A detector system using this technique has been constructed. Tests showed that anti-tank mines can reliably be found, but that, depending on the circumstances, anti-personnel mines may escape detection. A first test with a pulsed neutron generator shows that further improvements can be achieved by applying a window on the neutron transit time.

  17. The status of the Delft University Neutron Backscatter Landmine Detector (DUNBLAD)

    Energy Technology Data Exchange (ETDEWEB)

    Bom, V.R. E-mail: vb@iri.tudelft.nl; Datema, C.P. E-mail: cor.datema@philips.com; Eijk, C.W.E. van E-mail: vaneijk@iri.tudelft.nl

    2004-07-01

    The neutron backscattering technique may be applied to search for non-metallic landmines in relatively dry soils. A detector system using this technique has been constructed. Tests showed that anti-tank mines can reliably be found, but that, depending on the circumstances, anti-personnel mines may escape detection. A first test with a pulsed neutron generator shows that further improvements can be achieved by applying a window on the neutron transit time.

  18. Approach to simultaneously denoise and invert backscatter and extinction from photon-limited atmospheric lidar observations.

    Science.gov (United States)

    Marais, Willem J; Holz, Robert E; Hu, Yu Hen; Kuehn, Ralph E; Eloranta, Edwin E; Willett, Rebecca M

    2016-10-10

    Atmospheric lidar observations provide a unique capability to directly observe the vertical column of cloud and aerosol scattering properties. Detector and solar-background noise, however, hinder the ability of lidar systems to provide reliable backscatter and extinction cross-section estimates. Standard methods for solving this inverse problem are most effective with high signal-to-noise ratio observations that are only available at low resolution in uniform scenes. This paper describes a novel method for solving the inverse problem with high-resolution, lower signal-to-noise ratio observations that are effective in non-uniform scenes. The novelty is twofold. First, the inferences of the backscatter and extinction are applied to images, whereas current lidar algorithms only use the information content of single profiles. Hence, the latent spatial and temporal information in noisy images are utilized to infer the cross-sections. Second, the noise associated with photon-counting lidar observations can be modeled using a Poisson distribution, and state-of-the-art tools for solving Poisson inverse problems are adapted to the atmospheric lidar problem. It is demonstrated through photon-counting high spectral resolution lidar (HSRL) simulations that the proposed algorithm yields inverted backscatter and extinction cross-sections (per unit volume) with smaller mean squared error values at higher spatial and temporal resolutions, compared to the standard approach. Two case studies of real experimental data are also provided where the proposed algorithm is applied on HSRL observations and the inverted backscatter and extinction cross-sections are compared against the standard approach.

  19. Influence of backscattering on the spatial resolution of semiconductor X-ray detectors

    Science.gov (United States)

    Hoheisel, M.; Korn, A.; Giersch, J.

    2005-07-01

    Pixelated X-ray detectors using semiconductor layers or scintillators as absorbers are widely used in high-energy physics, medical diagnosis, or non-destructive testing. Their good spatial resolution performance makes them particularly suitable for applications where fine details have to be resolved. Intrinsic limitations of the spatial resolution have been studied in previous simulations. These simulations focused on interactions inside the conversion layer. Transmitted photons were treated as a loss. In this work, we also implemented the structure behind the conversion layer to investigate the impact of backscattering inside the detector setup. We performed Monte Carlo simulations with the program ROSI ( Roentgen Simulation) which is based on the well-established EGS4 algorithm. Line-spread functions of different fully implemented detectors were simulated. In order to characterize the detectors' spatial resolution, the modulation transfer functions (MTF) were calculated. The additional broadening of the line-spread function by carrier transport has been ignored in this work. We investigated two different detector types: a directly absorbing pixel detector where a semiconductor slab is bump-bonded to a readout ASIC such as the Medipix-2 setup with Si or GaAs as an absorbing semiconductor layer, and flat-panel detectors with a Se or a CsI converter. We found a significant degradation of the MTF compared to the case without backscattering. At energies above the K-edge of the backscattering material the spatial resolution drops and can account for the observed low-frequency drop of the MTF. Ignoring this backscatter effect might lead to misinterpretations of the charge sharing effect in counting pixel detectors.

  20. Assessing Seasonal Backscatter Variations with Respect to Uncertainties in Soil Moisture Retrieval in Siberian Tundra Regions

    Directory of Open Access Journals (Sweden)

    Elin Högström

    2014-09-01

    Full Text Available Knowledge of surface hydrology is essential for many applications, including studies that aim to understand permafrost response to changing climate and the associated feedback mechanisms. Advanced remote sensing techniques make it possible to retrieve a range of land-surface variables, including radar retrieved soil moisture (SSM. It has been pointed out before that soil moisture retrieval from satellite data can be challenging at high latitudes, which correspond to remote areas where ground data are scarce and the applicability of satellite data of this type is essential. This study investigates backscatter variability other than associated with changing soil moisture in order to examine the possible impact on soil moisture retrieval. It focuses on issues specific to SSM retrieval in the Arctic, notably variations related to tundra lakes. ENVISAT Advanced Synthetic Aperture Radar (ASAR Wide Swath (WS, 120 m data are used to understand and quantify impacts on Metop (AAdvanced Scatterometer (ASCAT, 25 km soil moisture retrieval during the snow free period. Sites of interest are chosen according to ASAR WS availability, high or low agreement between output from the land surface model ORCHIDEE and ASCAT derived SSM. Backscatter variations are analyzed with respect to the ASCAT footprint area. It can be shown that the low model agreement is related to water fraction in most cases. No difference could be detected between periods with floating ice (in snow off situation and ice free periods at the chosen sites. The mean footprint backscatter is however impacted by partial short term surface roughness change. The water fraction correlates with backscatter deviations (relative to a smooth water surface reference image within the ASCAT footprint areas (R = 0.91

  1. 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.

    : In EM 1002 system online amplifier gain correction is accomplished by applying mean backscattering coefficients such as: BS N and BS O applied at 0º and at crossover incidence angles (normally 25º) - 3 - respectively. Consequently the raw... processing analyses. Hence effort was made to have a processed imagery map for data acquired at NIO, which would support the seafloor geologic processes. The present software is written in C & C++ language and compiled on Dev C++ compiler. In short...

  2. Active-layer thickness estimation from X-band SAR backscatter intensity

    Science.gov (United States)

    Widhalm, Barbara; Bartsch, Annett; Leibman, Marina; Khomutov, Artem

    2017-02-01

    The active layer above the permafrost, which seasonally thaws during summer, is an important parameter for monitoring the state of permafrost. Its thickness is typically measured locally, but a range of methods which utilize information from satellite data exist. Mostly, the normalized difference vegetation index (NDVI) obtained from optical satellite data is used as a proxy. The applicability has been demonstrated mostly for shallow depths of active-layer thickness (ALT) below approximately 70 cm. Some permafrost areas including central Yamal are, however, characterized by larger ALT. Surface properties including vegetation structure are also represented by microwave backscatter intensity. So far, the potential of such data for estimating ALT has not been explored. We therefore investigated the relationship between ALT and X-band synthetic aperture radar (SAR) backscatter of TerraSAR-X (averages for 10 × 10 m window) in order to examine the possibility of delineating ALT with continuous and larger spatial coverage in this area and compare it to the already-established method of using NDVI from Landsat (30 m). Our results show that the mutual dependency of ALT and TerraSAR-X backscatter on land cover types suggests a connection of both parameters. A range of 5 dB can be observed for an ALT range of 100 cm (40-140 cm), and an R2 of 0.66 has been determined over the calibration sites. An increase of ALT with increasing backscatter can be determined. The root mean square error (RMSE) over a comparably heterogeneous validation site with maximum ALT of > 150 cm is 20 cm. Deviations are larger for measurement locations with mixed vegetation types (especially partial coverage by cryptogam crust) with respect to the spatial resolution of the satellite data.

  3. 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.

  4. Study of diffusion of indocyanine green as a photodynamic dye into skin using backscattering spectroscopy

    Science.gov (United States)

    Genina, E. A.; Bashkatov, A. N.; Tuchin, V. V.

    2014-07-01

    One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents.

  5. Study of diffusion of indocyanine green as a photodynamic dye into skin using backscattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Genina, E A; Bashkatov, A N; Tuchin, V V [N.G. Chernyshevsky Saratov State University, Saratov (Russian Federation)

    2014-07-31

    One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents. (laser biophotonics)

  6. Coherent keV backscattering from plasma-wave boosted relativistic electron mirrors

    CERN Document Server

    Li, F Y; Chen, M; Wu, H C; Liu, Y; Meyer-ter-Vehn, J; Mori, W B; Zhang, J

    2014-01-01

    A new parameter regime of laser wakefield acceleration driven by sub-petawatt femotsecond lasers is proposed, which enables the generation of relativistic electron mirrors further accelerated by the plasma wave. Integrated particle-in-cell simulation including the mirror formation and Thomson scattering demonstrates that efficient coherent backscattering up to keV photon energy can be obtained with moderate driver laser intensities and high density gas targets.

  7. Evaluation of the Doppler component contribution in the total backscattered flux for noninvasive medical spectroscopy

    Science.gov (United States)

    Lapitan, Denis; Rogatkin, Dmitry

    2014-05-01

    The widespread introduction of laser noninvasive diagnostic techniques in medicine gave rise interest to theoretical description of light propagation in turbid media. One of the purposes for that is a preliminary simulation of incoming radiation for diagnostic spectrophotometry equipment. For complex diagnostic devices combining the Laser Doppler Flowmetry (LDF) and the tissue reflectance oximetry (TRO) it is necessary to know a ratio of signals in each diagnostic channel for a proper choice of the radiation power of laser sources, sensitivity of photodetectors, etc. In LDF the lightbeating backscattered signal mixed from moving red blood cells and static inhomogeneities inside the tissue is the useful signal, while in TRO both signals from static and moving scatterers are registered in the sum. The aim of our study was an estimation of the ratio between flux with the Doppler shifted signal and the total backscattered flux. For this purpose the simple analytical model describing the backscattered radiation for a two-layered tissue with different levels of blood volume in the second layer was under consideration. The physical model was based on the improved Kubelka-Munk approach. This approach involves an additional parameter of the density of scatterers, so it is useful for the Doppler signal intensity calculation as well. To assess the intensity of the Doppler component the single-scattering approximation inside the tissue's second layer was used. It was found that the fraction of the Doppler component in the total backscattered flux can vary in the range of 1-10% for the blood volume of 1-20%.

  8. 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.

  9. Interface defects in GaN/sapphire studied using Rutherford backscattering spectroscopy and channeling

    Indian Academy of Sciences (India)

    S K Sinha; P K Barhai

    2004-06-01

    GaN on sapphire was grown by MOCVD technique. Rutherford backscattering spectra together with channeling along [0 0 0 1] axis were recorded to study the defects at the interface. Detailed calculation shows that the defects at GaN/sapphire interface are due to dislocations which are distributed into the whole thickness of the film and are mainly aligned on the growth direction.

  10. 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.

  11. Frequency shift of the Bragg and Non-Bragg backscattering from periodic water wave

    Science.gov (United States)

    Wen, Biyang; Li, Ke

    2016-08-01

    Doppler effect is used to measure the relative speed of a moving target with respect to the radar, and is also used to interpret the frequency shift of the backscattering from the ocean wave according to the water-wave phase velocity. The widely known relationship between the Doppler shift and the water-wave phase velocity was deduced from the scattering measurements data collected from actual sea surface, and has not been verified under man-made conditions. Here we show that this ob- served frequency shift of the scattering data from the Bragg and Non-Bragg water wave is not the Doppler shift corresponding to the water-wave phase velocity as commonly believed, but is the water-wave frequency and its integral multiple frequency. The power spectrum of the backscatter from the periodic water wave consists of serials discrete peaks, which is equally spaced by water wave frequency. Only when the water-wave length is the integer multiples of the Bragg wave, and the radar range resolution is infinite, does the frequency shift of the backscattering mathematically equal the Doppler shift according to the water-wave phase velocity.

  12. 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.

  13. The relationship between aboveground biomass and radar backscatter as observed on airborne SAR imagery

    Science.gov (United States)

    Kasischke, Eric S.; Bourgeau-Chavez, Laura L.; Christensen, Norman L., Jr.; Dobson, M. Craig

    1991-01-01

    The initial results of an experiment to examine the dependence of radar image intensity on total above-ground biomass in a southern US pine forest ecosystem are presented. Two sets of data are discussed. First, we examine two L-band (VV-polarization) data sets which were collected 5 years apart. These data sets clearly illustrate the change in backscatter resulting from the growth of a young pine stand. Second, we examine the dependence between radar backscatter and biomass as a function of radar frequency using data from the JPL Airborne Synthetic Aperture Radar (AIRSAR) and ERIM/NADC P-3 SAR systems. These results show that there is a positive correlation between above-ground biomass and radar backscatter and at C-, L-, and P-bands, but very little correlation at C-band. The biomass level for which this positive correlation holds decreases as radar frequency increases. This positive correlation is stronger at HH and HV polarizations that VV polarization at L- and P-bands, but strongest at VV polarization for C-band.

  14. Theory of anomalous backscattering in second harmonic X-mode ECRH experiments

    Science.gov (United States)

    Gusakov, E. Z.; Popov, A. Yu.

    2016-08-01

    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. 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.

  16. 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

    2017-02-01

    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.

  17. 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.

  18. Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar.

    Science.gov (United States)

    Foote, Kenneth G

    2012-05-01

    Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1-6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.

  19. A model for oxygen-dependent backscattering spectroscopic contrast from single red blood cells (Conference Presentation)

    Science.gov (United States)

    Liu, Rongrong; Yi, Ji; Chen, Siyu; Zhang, Hao F.; Backman, Vadim

    2016-03-01

    The oxygen-dependent absorption of hemoglobin provides the fundamental contrast for all label-free techniques measuring blood oxygenation. When hemoglobin is packaged into red blood cells (RBCs), the structure of the cells creates light scattering which also depends on the absorption based on the Kramers-Kronig relationship. Thus a proper characterization of the optical behaviors of blood has been a key to any accurate measurement of blood oxygenation, particularly at the capillary level where RBCs are dispersed individually in contrast to a densely packed whole blood. Here we provided a theoretical model under Born Approximation to characterize the oxygen dependent backscattering spectroscopic contrast from single RBCs. Using this theoretical model, we conducted simulations on both oxygenated and deoxygenated single RBCs with different sizes for standard and possible deformed cell geometries in blood flow, all which suggested similar backscattering spectroscopic contrast and were confirmed by Mie Theory and experiments using visible Optical Coherence Tomography (visOCT). As long as the cell size satisfies Gaussian distribution with a coefficient variance (C.V.) large enough, there is clear absorption contrast between the backscattering spectra of oxygenated and deoxygenated single RBCs calculated by this model, so oxygen saturation can then be characterized. Thus, this theoretical model can be extended to extract absorption features of other scattering particles as long as they satisfy Born Approximation.

  20. Ice Cloud Backscatter Study and Comparison with CALIPSO and MODIS Satellite Data

    Science.gov (United States)

    Ding, Jiachen; Yang, Ping; Holz, Robert E.; Platnick, Steven; Meyer, Kerry G.; Vaughan, Mark A.; Hu, Yongxiang; King, Michael D.

    2016-01-01

    An invariant imbedding T-matrix (II-TM) method is used to calculate the single-scattering properties of 8-column aggregate ice crystals. The II-TM based backscatter values are compared with those calculated by the improved geometric-optics method (IGOM) to refine the backscattering properties of the ice cloud radiative model used in the MODIS Collection 6 cloud optical property product. The integrated attenuated backscatter-to-cloud optical depth (IAB-ICOD) relation is derived from simulations using a CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) lidar simulator based on a Monte Carlo radiative transfer model. By comparing the simulation results and co-located CALIPSO and MODIS (Moderate Resolution Imaging Spectroradiometer) observations, the non-uniform zonal distribution of ice clouds over ocean is characterized in terms of a mixture of smooth and rough ice particles. The percentage of the smooth particles is approximately 6 percent and 9 percent for tropical and mid-latitude ice clouds, respectively.

  1. 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.

  2. Fluctuations in near-surface backscattering to a descending CW radar

    Science.gov (United States)

    Klibansky, Ben-Tsiyon

    1989-05-01

    The operation of a radar-activated proximity fuse in an artillery shell or mortar bomb depends on the Doppler modification of the echo as the projectile approaches the surface. Explosion at the correct height depends on the return signal amplitude, which strongly depends on the surface characteristics. Periodic modulations have been detected in the backscattering amplitude, as the projectile falls. Earth backscatter models were constructed as a basis for designing a fuse with improved distance measurement accuracy. For mortar bombs, most of the land models fit the data recorded, indicating that the sum of the returns from many scatterers creates the observed oscillation pattern. The return amplitude builds up very rapidly as the fuse approaches the earth. For flat trajectory projectiles, there is high frequency modulation of the return, which is attributed to the relatively high horizontal velocity component. Several models were found to fit the recorded surface backscatter data. The relationship between the return signal spectrum and the elevation angle suggests a possibility for improving the design and performance of the fuse electronic processor.

  3. Multiple scattering from Chebyshev particles: Monte Carlo simulations for backscattering in lidar geometry.

    Science.gov (United States)

    Mannoni, A; Flesia, C; Bruscaglioni, P; Ismaelli, A

    1996-12-20

    Lidar measurements are often interpreted on the basis of two fundamental assumptions: absence of multiple scattering and sphericity of the particles that make up the diffusing medium. There are situations in which neither holds true. We focus our interest on multiply-scattered returns from homogeneous layers of monodisperse, randomly oriented, axisymmetric nonspherical particles. T(2) Chebyshev particles have been chosen and their single-scattering properties have been reviewed. A Monte Carlo procedure has been employed to calculate the backscattered signal for several fields of view. Comparisons with the case of scattering from equivalent (equal-volume) spheres have been carried out (narrow polydispersions have been used to smooth the phase functions' oscillations). Our numerical effort highlights a considerable variability in the intensity of the multiply-scattered signal, which is a consequence of the strong dependence of the backscattering cross section on deformation of the particles. Even more striking effects have been noted for depolarization; peculiar behavior was observed at moderate optical depths when particles characterized by a large backscattering depolarization ratio were employed in our simulations. The sensitivity of depolarization to even small departures from sphericity, in spite of random orientation of the particles, has been confirmed. The results obtained with the Monte Carlo codes have been successfully checked with an analytical formula for double scattering.

  4. Height dependence of the observed spectrum of radar backscatter from HF-induced ionospheric Langmuir turbulence

    Science.gov (United States)

    Fejer, J. A.; Sulzer, M. P.; Djuth, F. T.

    1991-09-01

    Results are presented of observations of the spectrum of the 430-MHz radar backscatter from HF-induced Langmuir turbulence with height discrimination. During very stable ionospheric conditions under which the height of the below-threshold backscatter spectrum changed by less than 300 m during a 7-min period, a 20-s-long temporary increase in the HF power from 3 MW ERP to 38-MW-equivalent-radiated HF power is found to result in subsequent strong above-threshold spectra extending to heights up to 1200 m greater than the height of the below-threshold spectrum for more than a minute. The generation of irregularities in the plasma density during the 20 s of enhanced HF power is suggested as a possible cause of this persistence of strong above-threshold spectra at greater heights. The initial temporal evolution of the backscatter spectrum from Langmuir turbulence after the start of HF transmissions is observed for different heights. The observational results are compared with the predictions of existing theories of Langmuir turbulence.

  5. 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

    2017-01-01

    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. PMID:28198389

  6. 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)

  7. Development and demonstration of a high-altitude atmospheric backscatter Lidar system

    Science.gov (United States)

    Dolash, Thomas M.; Garvey, John; Leonelli, Joseph; Bradford, Mark; Rose, Lynn

    1994-06-01

    Battelle has designed and fabricated an upward-looking atmospheric backscatter lidar for high-altitude airborne applications. The compact, rugged system was assembled and integrated into a cupola on top of a Lear 36 aircraft to provide particle backscatter data and aerosol profile distributions of cirrus clouds occurring between 50,000 and 100,000 ft ASL. The high altitude airborne lidar system consists of a laser transmitter operating at 532 and 1064 nm simultaneously with output energy of 75 mJ at both wavelengths and a collecting telescope aperture of 10 inches in diameter. Laser backscatter energy is collected and directed via a dichroic beamsplitter to two avalanche photodetectors (APD) through narrow bandpass optical filters at 532 and 1064 nm. The outputs of the APDs are digitized by a 10-bit, 100-MHz transient digitizer before being recorded to a 1.2-Gbyte hard disk with IRIG timing for data analysis. This paper describes the lidar system design, predicted performance, and some of the operational challenges.

  8. Using SnowScat to characterize the backscatter response of water stress in an agricultural canopy

    Science.gov (United States)

    Steele-Dunne, S. C.; Werner, C.; Wiesmann, A.; de Pater, J.; van Emmerik, T. H.; Schuettemeyer, D.; Rommen, B.; Van De Giesen, N.

    2013-12-01

    SnowScat is a ground-based, fully polarimetric, coherent stepped frequency continuous wave scatterometer operating in the range of 9-18GHz. Since 2009, it has been employed in several field campaigns in Switzerland and Finland to investigate the backscatter characteristics of snow. In this presentation, we will give an overview of its first deployment in an agricultural application. In July 2013, it was installed above a maize canopy in Flevoland in the Netherlands. The objective is to characterize the backscatter response of vegetation in response to natural variations in moisture availability. Backscatter is measured hourly at a range of incident and elevation angles. Meteorological data, soil moisture profiles and vegetation stage are combined to quantify water stress. Regular destructive vegetation sampling and dielectric property measurements are used to monitor variations in the canopy water content. Additional ancillary measurements include temperature profiles and NDVI measurements. Here, we will present a description of the installation, a summary of the data collected and some preliminary results.

  9. 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...

  10. 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,...

  11. bh_1mBS.tif: Backscatter Imagery from Sidescan Sonar 1 meter/pixel of Boston Harbor and Approaches

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are high-resolution acoustic backscatter measurements of the seafloor from Boston Harbor and the harbor approaches, Massachusetts. Approximately 170 km²...

  12. 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...

  13. bh_1mBS.tif: Backscatter Imagery from Sidescan Sonar 1 meter/pixel of Boston Harbor and Approaches

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are high-resolution acoustic backscatter measurements of the seafloor from Boston Harbor and the harbor approaches, Massachusetts. Approximately 170 km²...

  14. 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...

  15. 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...

  16. Seafloor Backscatter Image of North of Santa Rosa Island, Channel Islands National Marine Sanctuary (8m resolution tif)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents an 8 meter resolution backscatter of the seafloor south of Santa Rosa Island in Channel Islands National Marine Sanctuary. It was acquired...

  17. CRED Reson 8101 multibeam backscatter data of Johnston 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 lagoon, shelf, and slope environments of Palmyra Atoll, Pacific Island Areas, Central Pacific....

  18. Reson 8101 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 300...

  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. 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...

  1. Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the Inner Continental Borderland, southern California

    Science.gov (United States)

    Dartnell, Peter; Driscoll, Neal W.; Brothers, Daniel S.; Conrad, James E.; Kluesner, Jared; Kent, Graham; Andrews, Brian D.

    2015-01-01

    In late 2013, Scripps Institution of Oceanography collected multibeam bathymetry and acoustic-backscatter data of the Inner Continental Borderland Region, Southern California. The U.S. Geological Survey Pacific Coastal and Marine Science Center processed these data, and this report provides the data in a number of different formats in addition to a set of map sheets. The data catalog provides the new bathymetry and acoustic-backscatter data, collected mainly in the Gulf of Santa Catalina and San Diego Trough, as well as this new bathymetry data merged with other publically available bathymetry data from the region. Sheet 1 displays a colored shaded-relief bathymetry map of the Inner Continental Borderland generated from the merged bathymetry data. Sheet 2 displays the new acoustic-backscatter data along with other available backscatter data in the region. Sheet 3 displays selected perspective views of the bathymetry data highlighting submarine canyon and channel systems, knolls, and tectonic features.

  2. 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...

  3. 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...

  4. 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....

  5. 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...

  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. CRED Reson 8101 multibeam backscatter data of Howland 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 Howland Atoll, Pacific Island Areas, Central Pacific. These...

  8. 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....

  9. Correction: Spectroscopic characteristics of the OSIRIS near-backscattering crystal analyser spectrometer on the ISIS pulsed neutron source.

    Science.gov (United States)

    Telling, Mark T F; Campbell, Stuart I; Engberg, Dennis; Martín Y Marero, David; Andersen, Ken H

    2016-03-21

    Correction for 'Spectroscopic characteristics of the OSIRIS near-backscattering crystal analyser spectrometer on the ISIS pulsed neutron source' by Mark T. F. Telling et al., Phys. Chem. Chem. Phys., 2005, 7, 1255-1261.

  10. The use of multibeam backscatter intensity data as a tool for mapping glacial deposits in the Central North Sea, UK

    Science.gov (United States)

    Stewart, Heather; Bradwell, Tom

    2014-05-01

    Multibeam backscatter intensity data acquired offshore eastern Scotland and north-eastern England have been used to map drumlin fields, large arcuate moraine ridges, smaller scale moraine ridges, and incised channels on the sea floor. The study area includes the catchments of the previously proposed, but only partly mapped, Strathmore, Forth-Tay, and Tweed palaeo-ice streams. The ice sheet glacial landsystem is extremely well preserved on the sea bed and comprehensive mapping of the seafloor geomorphology has been undertaken. The authors demonstrate the value in utilising not only digital terrain models (both NEXTMap and multibeam bathymetry derived) in undertaking geomorphological mapping, but also examining the backscatter intensity data that is often overlooked. Backscatter intensity maps were generated using FM Geocoder by the British Geological Survey. FM Geocoder corrects the backscatter intensities registered by the multibeam echosounder system, and then geometrically corrects and positions each acoustic sample in a backscatter mosaic. The backscatter intensity data were gridded at the best resolution per dataset (between 2 and 5 m). The strength of the backscattering is dependent upon sediment type, grain size, survey conditions, sea-bed roughness, compaction and slope. A combination of manual interpretation and semi-automated classification of the backscatter intensity data (a predictive method for mapping variations in surficial sea-bed sediments) has been undertaken in the study area. The combination of the two methodologies has produced a robust glacial geomorphological map for the study area. Four separate drumlin fields have been mapped in the study area indicative of fast-flowing and persistent ice-sheet flow configurations. A number of individual drumlins are also identified located outside the fields. The drumlins show as areas of high backscatter intensity compared to the surrounding sea bed, indicating the drumlins comprise mixed sediments of

  11. Statistics of the integrated backscatter estimate from a blood-mimicking fluid.

    Science.gov (United States)

    Cakareski, E; Pedersen, P C

    2001-11-01

    This work evaluates the variance of the integrated backscatter (IBS) from moving blood [or blood-mimicking fluid (bmf)] as a way of determining the quality of the mean IBS estimate. The main motivation for this work comes from the fact that absolute IBS values from tissues adjacent to arterial blood can be found by normalizing the measured backscatter energy with the IBS of moving, deaggregated blood. The paper describes the parameters that control the statistics of the IBS estimate, which is calculated for the stochastic ultrasound backscatter signals from flowing blood. It further formulates how the measurement parameters should be specified so that an appropriately low blood IBS variance is ensured or, alternatively, a specified accuracy of the tissue IBS estimate is obtained. First, the paper provides an analytic formulation of the statistics of the IBS, based on a sequence of sampled echoes from a nonstationary Gaussian scattering medium. The analysis incorporates the correlation between the sample values as well as the correlation between the IBS of the individual echoes. The estimate of the mean IBS has been shown to be chi-squared distributed with a determinable order. With the degree of correlation between the samples and between the IBS of individual echoes specified, the number of measurements required to obtain an IBS estimate with a specified variance is readily calculated. Next, a sequence of synthetic echoes is produced and arranged as columns in a data matrix. The echoes are generated such that the second-order statistics along the rows and columns of the matrix match that of actually observed echoes. The actual variance of the mean IBS estimate for the synthetic echoes is calculated and compared with the variance determined from the analytic model, and a good agreement has been found. Finally, sequences of actual backscattered echoes from circulating blood-mimicking fluid are acquired and analyzed to determine the variance of their mean IBS

  12. Clinical Study of Ultrasonic Tissue Characterization with Integrated Backscatter and Echo Intensity in the Diagnosis of Acute Myocardial Infarction

    Institute of Scientific and Technical Information of China (English)

    王志刚; 冉海涛; 黄晶; 陈庆伟; 邹建中; 苏海兵; 蒲世玉; 凌智瑜; 陈永新; 何明菊

    2001-01-01

    Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks after acute myocardial infarction, 35 patients underwent ultrasonic tissue characterization from the papillary short- axis view.The cyclic variation of integrated backscatter and echo intensity of three different myocardial regions perfused by left anterior descending coronary artery, left cir cumflex coronary and right coronary were measured .The value of cyclic variation of integrated backscatter and integrated backscatter and echo intensity ≤ half of the highest value of three different myocardial regions on a same view were define as the criteria for diag nosing acute myocardial infarction , and the results were compared with coronary angiography. The sensitivity of diagnosing acute myocardial infarction by both Ultrasonic tissue characterization with integrated backscatter and echo intensity were 91.43 % . The location of myocardial infarction detected by this technique corresponded with the damaged myocardial region determined by coronary angiography. Conclusions Ultrasonic tissue characterization with integrated backscatter and echo intensity could clinically be used as a noninvasive approach in the diagnosis of acute myocardial infarction.

  13. The Tor Vergata Scattering Model Applied to L Band Backscatter During the Corn Growth Cycle

    Science.gov (United States)

    Joseph, A. T.; van der Velde, R.; Ferrazzoli, P.; Lang, R. H.; Gish, T.

    2013-12-01

    At the USDA's Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) experimental site in Beltsville (Maryland, USA) a field campaign took place throughout the 2002 corn growth cycle from May 10th (emergence of corn crops) to October 2nd (harvest). One of the microwave instruments deployed was the multi-frequency (X-, C- and L-band) quad-polarized (HH, HV, VV, VH) NASA GSFC / George Washington University (GWU) truck mounted radar. During the field campaign, this radar system provided once a week fully polarized C- and L-band (4.75 and 1.6 GHz) backscatter measurements from incidence angle of 15, 35, and 55 degrees. In support of these microwave observations, an extensive ground characterization took place, which included measurements of surface roughness, soil moisture, vegetation biomass and morphology. The field conditions during the campaign are characterized by several dry downs with a period of drought in the month of August. Peak biomass of the corn canopies was reached at July 24, 2002 with a total biomass of approximately 6.5 kg m-2. This dynamic range in both soil moisture and vegetation conditions within the data set is ideal for the validation of discrete medium vegetation scattering models. In this study, we compare the L band backscatter measurements with simulations by the Tor Vergata model (Bracaglia et al., 1995). The measured soil moisture, vegetation biomass and most reliably measured vegetation morphological parameters (e.g. number of leaves, number of stems and stem height) were used as input for the Tor Vergata model. The more uncertain model parameters (e.g. surface roughness, leaf thickness) and the stem diameter were optimized using a parameter estimation routine based on the Levenberg-Marquardt algorithm. As cost function for this optimization, the HH and VV polarized backscatter measured and simulated by the Tor Vergata model for incidence angle of 15, 35 and 55 degrees were used (6 measurements in total). The

  14. Backscattering characteristics Analyses of winter wheat covered area and Drought Monitoring Based on active microwave

    Science.gov (United States)

    Zhang, C., Sr.; Li, L.

    2015-12-01

    The advantage of active microwave remote sensing on the sensitivity of polarization characteristic, backscatter intensity and phase characteristics to soil moisture demonstrates its potential to map and monitor relative soil moisture changes and drought information with high spatial resolution. However, the existence of soil surface condition and vegetation effects confounds the retrieval of soil moisture from active microwave, and therefore limits its applications on soil moisture retrieval and drought monitoring. To research how to reduce the effect of soil roughness and wheat cover with multi- incident angles and multi polarization active microwave remote sensing data, MIMICS and AIEM models were used to simulate the backscattering coefficient of winter wheat covered field. The interaction between winter wheat at main growth stages and microwave was analyzed. The effects of surface roughness and physical parameters of wheat on the backscattering characteristics and the variation of different incident angles and different polarization conditions are simulated and analyzed emphatically. Then scattering coefficient information of winter wheat covered area at different wheat growth stage was measured with a C band ground-based scattering meter. At the same time, biomass, leaf area index and soil rough degree, soil water content and other related parameters are collected. After comparing and analyzing the measured data and the simulated data at different incident angles and different polarization modes, we propose an approach of using multi polarization and multi angle data to eliminate the soil roughness and wheat vegetation effects and performing the inversion of soil moisture. Using the Radarsat2 satellite SAR data and ground-based scatter data gotten at the same period in 2012, soil moisture information of greater area is obtained, and then the drought information is obtained, which is consistent with the measured results.

  15. Investigation of Backscatter X-ray imaging techniques for Uranium Dioxide Fuel Rods

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Timothy D [Rensselaer Polytechnic Institute (RPI); Hollenbach, Daniel F [ORNL; Shedlock, Daniel [Nucsafe, Inc.

    2011-01-01

    Radiography by Selective Detection (RSD), was investigated for its ability to determine the presence and types of defects in a UO{sub 2} fuel rod surrounded by zirconium cladding. Images created using a Monte Carlo model compared favorably with actual X-ray backscatter images from mock fuel rods. A fuel rod was modeled as a rectangular parallelepiped with zirconium cladding, and pencil beam X-ray sources of 160 kVp (79 keV avg) and 480 kVp (218 keV avg) were generated using the Monte Carlo N-Particle Transport Code to attempt to image void and palladium (Pd) defects in the interior and on the surface of the fuel pellet. It was found that the 160 kVp spectrum was unable to detect the presence of interior defects, whereas the 480 kVp spectrum detected them with both the standard and the RSD backscatter methods, though the RSD method was very inefficient. It was also found that both energy spectra were able to detect void and Pd defects on the surface using both imaging methods. Additionally, two mock fuel rods were imaged using a backscatter X-ray imaging system, one consisting of hafnium pellets in a Zircaloy-4 cladding and the other consisting of steel pellets in a Zircalloy-4 cladding which was then encased in a steel cladding (a double encapsulation configuration employed in irradiation and experiments). It was found that the system was capable of detecting individual HfO{sub 2} pellets in a Zircaloy-4 cladding and may be capable of detecting individual steel pellets in the double-encapsulated sample. It is expected that the system would also be capable of detecting individual UO{sub 2} pellets in a Zircaloy-4 cladding, though no UO{sub 2} fuel rod was available for imaging.

  16. Ceilometer lidar comparison: backscatter coefficient retrieval and signal-to-noise ratio determination

    Directory of Open Access Journals (Sweden)

    B. Heese

    2010-12-01

    Full Text Available The potential of a new generation of ceilometer instruments for aerosol monitoring has been studied in the Ceilometer Lidar Comparison (CLIC study. The used ceilometer was developed by Jenoptik, Germany, and is designed to find both thin cirrus clouds at tropopause level and aerosol layers at close ranges during day and night-time. The comparison study was performed to determine up to which altitude the ceilometers are capable to deliver particle backscatter coefficient profiles. For this, the derived ceilometer profiles are compared to simultaneously measured lidar profiles at the same wavelength. The lidar used for the comparison was the multi-wavelengths Raman lidar PollyXT. To demonstrate the capabilities and limits of ceilometers for the derivation of particle backscatter coefficient profiles from their measurements two examples of the comparison results are shown. Two cases, a daytime case with high background noise and a less noisy night-time case, are chosen. In both cases the ceilometer profiles compare well with the lidar profiles in atmospheric structures like aerosol layers or the boundary layer top height. However, the determination of the correct magnitude of the particle backscatter coefficient needs a calibration of the ceilometer data with an independent measurement of the aerosol optical depth by a sun photometer. To characterizes the ceilometers signal performance with increasing altitude a comprehensive signal-to-noise ratio study was performed. During daytime the signal-to-noise ratio is higher than 1 up to 4–5 km depending on the aerosol content. In our night-time case the SNR is higher than 1 even up to 8.5 km, so that also aerosol layers in the upper troposphere had been detected by the ceilometer.

  17. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 1; Methods and Comparisons

    Science.gov (United States)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Leifer, R.

    1998-01-01

    This paper examines the aerosol backscattering and extinction profiles measured at night by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site in April 1994. These lidar data are used to derive aerosol profiles for altitudes between 0.0 1 5 and 5 km. Since this lidar detects Raman scattering from nitrogen and oxygen molecules as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously. The aerosol extinction/backscattering ratio varied between approximately 30 sr and 75 sr at 351 nm. Aerosol optical thicknesses derived by integrating the lidar profiles of aerosol extinction measured at night between 0. I and 5 km are found to be about 10-40% lower than those measured by a Sun photometer during the day. This difference is attributed to the contribution by stratospheric aerosols not included in the lidar estimates as well as to diurnal differences in aerosol properties and concentrations. Aerosol profiles close to the surface were acquired by pointing the lidar nearly horizontally. Measurements of aerosol scattering from a tower-mounted nephelometer are found to be 40% lower than lidar measurements of aerosol extinction over a wide range of relative humidities even after accounting for the difference in wavelengths. The reasons for this difference are not clear but may be due to the inability of the nephelometer to accurately measure scattering by large particles.

  18. Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

    Directory of Open Access Journals (Sweden)

    T. Maruyama

    2006-03-01

    Full Text Available During the SEEK 2 rocket campaign, ionograms were recorded every minute at the Yamagawa Radio Observatory at about 90km west of the region monitored by a VHF (very high frequency coherent backscatter radar. Sporadic E-layer parameters, which include the critical (foEs and blanketing (fbEs frequencies, the layer height (h'Es, and the width of the range spread of sporadic E-traces, were compared with RTI (range-time-intensity plots of VHF quasi-periodic (QP and continuous coherent backscatter echoes. A close relationship was found between the appearance of QP echoes in the RTI plots and the level of spatial inhomogeneity in sporadic E plasma, signified here by the difference between foEs and fbEs. During QP echo events, foEs increased while fbEs decreased, so that the difference foEs-fbEs was enhanced, indicating the development of strong spatial structuring in electron density within a sporadic E-layer. On the other hand, increases in sporadic E range spreading also correlated with the occurrence of QP echoes but the degree of correlation varied from event to event. Continuous radar echoes were observed in association with low altitude sporadic E-layers, located well below 100 km and at times as low as 90 km. During the continuous echo events, both foEs and fbEs were less variable, and the difference foEs-fbEs was small and not as dynamic as in the QP echoes. On the other hand, the Es-layer spread intensified during continuous echoes, which means that some patchiness or corrugation in those low altitude layers is also necessary for the continuous backscatter echoes to take place.

  19. On the collocation between dayside auroral activity and coherent HF radar backscatter

    Directory of Open Access Journals (Sweden)

    J. Moen

    Full Text Available The 2D morphology of coherent HF radar and optical cusp aurora has been studied for conditions of predominantly southward IMF conditions, which favours low-latitude boundary layer reconnection. Despite the variability in shape of radar cusp Doppler spectra, the spectral width criterion of > 220 m s–1 proves to be a robust cusp discriminator. For extended periods of well-developed radar backscatter echoes, the equatorward boundary of the > 220 m s–1 spectral width enhancement lines up remarkably well with the equatorward boundary of the optical cusp aurora. The spectral width boundary is however poorly determined during development and fading of radar cusp backscatter. Closer inspection of radar Doppler profile characteristics suggests that a combination of spectral width and shape may advance boundary layer identification by HF radar. For the two December days studied the onset of radar cusp backscatter occurred within pre-existing 630.0 nm cusp auroral activity and appear to be initiated by sunrise, i.e. favourable radio wave propagation conditions had to develop. Better methods are put forward for analysing optical data, and for physical interpretation of HF radar data, and for combining these data, as applied to detection, tracking, and better understanding of dayside aurora. The broader motivation of this work is to develop wider use by the scientific community, of results of these techniques, to accelerate understanding of dynamic high-latitude boundary-processes. The contributions in this work are: (1 improved techniques of analysis of observational data, yielding meaningfully enhanced accuracy for deduced cusp locations; (2 a correspondingly more pronounced validation of correlation of boundary locations derived from the observational data set; and (3 a firmer physical rationale as to why the good correlation observed should theoretically be expected.

    Key words: Ionosphere (ionospheric

  20. Backscattering/transmission of 2 MeV He{sup ++} ions quantitative correlation study

    Energy Technology Data Exchange (ETDEWEB)

    Berec, V., E-mail: bervesn@gmail.com [Institute of Nuclear Sciences Vinca, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Germogli, G.; Mazzolari, A.; Guidi, V. [INFN Sezione di Ferrara and Dipartimento di Fisica e Scienze della Terra, Via Saragat 1, 44100 Ferrara (Italy); De Salvador, D. [Dipartimento di Fisica, Università di Padova, Via Marzolo n.8, 35131 Padova (Italy); INFN Laboratori Nazionali di Legnaro, Viale Università 2, 35020 Legnaro, PD (Italy); Bacci, L. [INFN Laboratori Nazionali di Legnaro, Viale Università 2, 35020 Legnaro, PD (Italy)

    2015-07-15

    In this work we report on detailed findings of planar channeling oscillations of 2 MeV He{sup ++} particles in (1 1 0) silicon crystal. The exact correlation and coherence mechanism between confined particles oscillating trajectories are analyzed theoretically and experimentally in backscattering/transmission geometry. Regular patterns of channeled He{sup ++} ion planar oscillations are shown to be dominated by the crystal harmonic-oscillator potential and multiple scattering effect. For the first time it was shown that under the planar channeling conditions trajectories of positively charged particles exhibit observable correlation dynamics, including the interference effect. Quantitative estimation of channeling efficiency is performed using path integral method.

  1. Backscattering in a 2D topological insulator and the conductivity of a 2D strip

    Science.gov (United States)

    Magarill, L. I.; Entin, M. V.

    2015-01-01

    A strip of the 2D HgTe topological insulator is studied. The same-spin edge states in an ideal system propagate in opposite directions on different sides of the strip and do not mix by tunneling. Impurities, edge irregularities, and phonons produce transitions between the counterpropagating edge states on different edges. This backscattering determines the conductivity of an infinitely long strip. The conductivity at finite temperature is determined in the framework of the kinetic equation. It is found that the conductivity exponentially grows with the strip width. In the same approximation the nonlocal resistance coefficients of a four-terminal strip are found.

  2. 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.

    , the application of the theory for deep seafloor quantitative backscatter model using multibeam echosounder was initiated [5-7] In the composite roughness model, Jackson et al [9] had applied power law properties of the seafloor roughness spectrum to a H...-K formulation at steep 'angles i.e , angles of incidences in the range 020 The mathematical aspects ot the composite toughness theory are given elsewhere For a small-scale part ofthe seafloor the composite roughness model uses the Rayieigh-Ricc perturbation...

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

    Science.gov (United States)

    Zhang, Xiaodong; Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D.; Hayward, Jason P.

    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.

  4. Characterization of the energy response and backscatter contribution for two electronic personal dosimeter models.

    Science.gov (United States)

    Meier, Joseph; Kappadath, S Cheenu

    2015-11-08

    We characterized the energy response of personal dose equivalent (Hp(10) in mrem) and the contribution of backscatter to the readings of two electronic personal dosimeter (EPD) models with radionuclides commonly used in a nuclear medicine clinic. The EPD models characterized were the RADOS RAD-60R, and the SAIC PD-10i. The experimental setup and calculation of EPD energy response was based on ANSI/HPS N13.11-2009. Fifteen RAD-60R and 2 PD-10i units were irradiated using (99m)Tc, (131)I, and (18)F radionuclides with emission energies at 140 keV, 364 keV, and 511 keV, respectively. At each energy, the EPDs output in Hp(10) [mrem] were recorded with 15 inch thick PMMA to simulate backscatter form the torso. Simultaneous free-in-air exposure rate measurements were also performed using two Victoreen ionization survey meters to calculate the expected EPD Hp(10) values per ANSI/HPS N13.11-2009. The energy response was calculated by taking the ratio of the EPD Hp(10) readings with the expected Hp(10) readings and a two-tailed z-test was used to determine the significance of the ratio deviating away from unity. The contribution from backscatter was calculated by taking the ratio of the EPD Hp(10) readings with and without backscatter material. A paired, two-tailed t-test was used to determine the significance of change in EPD Hp(10) readings. The RAD-60R mean energy response at 140 keV was 0.85, and agreed to within 5% and 11% at 364 and 511 keV, respectively. The PD-10i mean energy response at 140 keV was 1.20, and agreed to within 5% at 364 and 511 keV, respectively. On average, in the presence of acrylic, RAD-60R values increased by 32%, 12%, and 14%, at 140, 364, and 511 keV, respectively; all increases were statistically significant. The PD-10i increased by 25%, 19%, and 10% at 140 keV, 364 keV, and 511 keV, respectively; however, only the 140 keV measurement was statistically significant. Although both EPD models performed within the manufacturers' specifications of

  5. Determination of nitrogen content in thick TiN layers by proton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Havranek, V.; Hnatowicz, V.; Kvitek, J. (Nuclear Physics Inst., Czechoslovak Academy of Sciences, Rez (Czechoslovakia)); Musil, J.; Poulek, V. (Inst. of Physics, Czechoslovak Academy of Sciences, Prague (Czechoslovakia))

    1990-06-01

    Non-Rutherford proton backscattering has been employed for the determination of the nitrogen content in TiN layers of a thickness of several micrometres deposited on a steel backing. The required proton scattering cross section has been measured using standards comprising thin TiN films on a light substrate. The scattering cross section of 2 MeV protons of nitrogen for {theta}{sub lab}=160deg was found to be 5.7 times the Rutherford value. Nitrogen detection limits in thick TiN samples are discussed. (orig.).

  6. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Science.gov (United States)

    Sedao, Xxx; Maurice, Claire; Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie; Quey, Romain; Blanc, Gilles; Pigeon, Florent

    2014-05-01

    We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1-3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  7. Backscattered radiation into a transmission ionization chamber: measurement and Monte Carlo simulation.

    Science.gov (United States)

    Yoshizumi, Maíra T; Yoriyaz, Hélio; Caldas, Linda V E

    2010-01-01

    Backscattered radiation (BSR) from field-defining collimators can affect the response of a monitor chamber in X-radiation fields. This contribution must be considered since this kind of chamber is used to monitor the equipment response. In this work, the dependence of a transmission ionization chamber response on the aperture diameter of the collimators was studied experimentally and using a Monte Carlo (MC) technique. According to the results, the BSR increases the chamber response of over 4.0% in the case of a totally closed collimator and 50 kV energy beam, using both techniques. The results from Monte Carlo simulation confirm the validity of the simulated geometry.

  8. Characteristics of CALIOP attenuated backscatter noise: implication for cloud/aerosol detection

    Directory of Open Access Journals (Sweden)

    D. L. Wu

    2010-07-01

    Full Text Available To study cloud/aerosol features in the upper troposphere and lower stratosphere (UT/LS with the NASA's A-Train sensors, a research algorithm is developed for a re-gridded CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization Level 1 (L1 backscatter dataset. This paper provides a detailed analysis of the measurement noise of this re-gridded dataset in order to compare the lidar measurements with other collocated measurements (e.g., CloudSat, Microwave Limb Sounder. The re-gridded dataset has a manageable data volume for multi-year analysis. It has a fixed (5 km horizontal resolution, and the measurement error is derived empirically from the background-corrected backscatter profile on a profile-by-profile basis. The 532-nm and 1064-nm measurement noises, determined from the data at altitudes above 19 km, are analyzed and characterized in terms of the mean (μ, standard deviation (σ, and normalized probability density function (PDF. These noises show a larger variance over landmasses and bright surfaces during day, and in regions with enhanced flux of energetic particles during night, where the instrument's ability for feature detection is slightly degraded. An increasing trend in the nighttime 1064-nm σ appears to be significant, which likely causes the increasing differences in cloud occurrence frequency between the 532-nm and 1064-nm channels. Most of the CALIOP backscatter noise distributions exhibit a Gaussian-like behavior but the nighttime 532-nm perpendicular measurements show multi-Gaussian characteristics. We apply σ – based thresholds to detect cloud/aerosol features in the UT/LS from the subset L1 data. The observed morphology is similar to that from the Level 2 (L2 05km_CLAY+05km_ALAY product, but the occurrence frequency obtained in this study is slightly lower than the L2 product due to differences in spatial averaging and detection threshold. In the case where the measurement noises of two data sets are different, the

  9. Backscattering of waves of a two-scale rough surface with allowance for rereflections

    Science.gov (United States)

    Zavorotnyi, V. U.

    An analysis is made of wave scattering by a surface with small-scale and large-scale (as compared with the wavelength) roughnesses. Kur'ianov's method is refined by allowing for rereflections. An expression is derived for the mean intensity of the diffuse component of the scattered field in the case of an arbitrary configuration of the large-scale component of the surface. In the case of backscattering there occurs coherent summation of several field components, which is connected with the presence of rereflections on the surface. The results are pertinent to wave scattering by the sea surface.

  10. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    Directory of Open Access Journals (Sweden)

    Tsekeri Alexandra

    2016-01-01

    Full Text Available Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015.

  11. Applications of interferometrically derived terrain slopes: Normalization of SAR backscatter and the interferometric correlation coefficient

    Science.gov (United States)

    Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.

    1994-01-01

    Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.

  12. Phase analysis on dual-phase steel using band slope of electron backscatter diffraction pattern.

    Science.gov (United States)

    Kang, Jun-Yun; Park, Seong-Jun; Moon, Man-Been

    2013-08-01

    A quantitative and automated phase analysis of dual-phase (DP) steel using electron backscatter diffraction (EBSD) was attempted. A ferrite-martensite DP microstructure was produced by intercritical annealing and quenching. An EBSD map of the microstructure was obtained and post-processed for phase discrimination. Band slope (BS), which was a measure of pattern quality, exhibited much stronger phase contrast than another conventional one, band contrast. Owing to high sensitivity to lattice defect and little orientation dependence, BS provided handiness in finding a threshold for phase discrimination. Its grain average gave a superior result on the discrimination and volume fraction measurement of the constituent phases in the DP steel.

  13. Estimation of light transport parameters in biological media using coherent backscattering

    Indian Academy of Sciences (India)

    S Anantha Ramakrishna; K Divakara Rao

    2000-02-01

    The suitability of using the angular peak shape of the coherent backscattered light for estimating the light transport parameters of biological media has been investigated. Milk and methylene blue doped milk were used as tissue phantoms for the measurements carried out with a He–Ne laser (632.8 nm). Results indicate that while the technique accurately estimates the transport length, it can determine the absorption coefficient only when the absorption is moderately high ( > 1 cm-1) for the long transport lengths typical of tissues. Further, the possibility of determining the anisotropy factor by estimating the single scattering contribution to the diffuse background is examined.

  14. Time evolution analysis of the electron distribution in Thomson/Compton back-scattering

    Energy Technology Data Exchange (ETDEWEB)

    Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R. [INFN-Universitá degli Studi Milano, Via Celoria, 16 20133 Milano (Italy)

    2013-07-28

    We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

  15. Time evolution analysis of the electron distribution in Thomson/Compton back-scattering

    Science.gov (United States)

    Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R.

    2013-07-01

    We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

  16. Ultrasound backscatter from free-swimming fish at 1 MHz for fish identification

    DEFF Research Database (Denmark)

    Pham, An Hoai; Lundgren, Bo; Stage, Bjarne

    2012-01-01

    MHz from fish. The system consists of a Reson TC3210 1 MHz single-element transducer, a dual-frequency, multi-beam Blueview P900-2250 sonar, and three Oregon ATC9K cameras. The Reson transducer is connected to an Olympus pulser-receiver monitored by a portable computer through a Picoscope 4226 PC......In the frequency range well below 1 MHz, the swimbladder is often considered the most important part for acoustic fish detection. In this work a portable system was developed to not only detect but also try to identify free-swimming fish. It has been used to measure the ultrasound backscatter at 1...

  17. Raman backscatter as a remote laser power sensor in high-energy-density plasmas

    CERN Document Server

    Moody, J D; Divol, L; Michel, P; Robey, H F; LePape, S; Ralph, J; Ross, J S; Glenzer, S H; Kirkwood, R K; Landen, O L; MacGowan, B J; Nikroo, A; Williams, E A

    2013-01-01

    Stimulated Raman backscatter (SRS) is used as a remote sensor to quantify the instantaneous laser power after transfer from outer to inner cones that cross in a National Ignition Facility (NIF) gas-filled hohlraum plasma. By matching SRS between a shot reducing outer vs a shot reducing inner power we infer that ~half of the incident outer-cone power is transferred to inner cones, for the specific time and wavelength configuration studied. This is the first instantaneous non-disruptive measure of power transfer in an indirect drive NIF experiment using optical measurements.

  18. Application of the Tor Vergata Scattering Model to L Band Backscatter During the Corn Growth Cycle

    Science.gov (United States)

    Joseph, A. T.; vanderVelde, R.; ONeill, P. E.; Lang, R.; Gish, T.

    2010-01-01

    At the USDA's Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) experimental site in Beltsville, Maryland, USA) a field campaign took place throughout the 2002 corn growth cycle from May 10th (emergence of corn crops) to October 2nd (harvest). One of the microwave instruments deployed was the multi-frequency (X-, C- and L-band) quad-polarized (HH, HV, VV, VH) NASA GSFC/George Washington University (GWU) truck mounted radar. During the field campaign, this radar system provided once a week fully polarized C- and L-band (4.75 and 1.6 GHz) backscatter measurements from incidence angle of 15, 35, and 55 degrees. In support of microwave observations, an extensive ground characterization took place, which included measurements of surface roughness, soil moisture, vegetation biomass and morphology. The field conditions during the campaign are characterized by several dry downs with a period of drought in the month of August. Peak biomass the corn canopies was reached on July 24th with a total biomass of approximately 6.5 kg/sq m. This dynamic range in both soil moisture and vegetation conditions within the data set is ideal for the validation of discrete medium vegetation scattering models. In this study, we compare the L band backscatter measurements with simulations by the Tor Vergata model (ferrazzoli and Guerriero 1996). The measured soil moisture, vegetation biomass and most reliably measured vegetation morphological parameters (e.g. number of leaves, number of stems and stem height) were used as input for the Tor Vergata model. The more uncertain model parameters (e.g. surface roughness, leaf thickness) and the stem diameter were optimized using a parameter estimation routine based on the Levenberg-Marquardt algorithm. As cost function for this optimization, the HH and VV polarized backscatter measured and stimulated by the TOR Vergata model for incidence angle of 15, 35, and 55 degrees were used (6 measurements in total). The calibrated

  19. A new gradient monochromator for the IN13 back-scattering spectrometer

    Science.gov (United States)

    Ciampolini, L.; Bove, L. E.; Mondelli, C.; Alianelli, L.; Labbe-Lavigne, S.; Natali, F.; Bée, M.; Deriu, A.

    2005-06-01

    We present new McStas simulations of the back-scattering thermal neutron spectrometer IN13 to evaluate the advantages of a new temperature gradient monochromator relative to a conventional one. The simulations show that a flux gain up to a factor 7 can be obtained with just a 10% loss in energy resolution and a 20% increase in beam spot size at the sample. The results also indicate that a moderate applied temperature gradient (ΔT≃16 K) is sufficient to obtain this significant flux gain.

  20. A new gradient monochromator for the IN13 back-scattering spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ciampolini, L. [Istituto Nazionale per la Fisica della Materia, Unita di Parma (Italy)]. E-mail: ciampolinil@ieee.org; Bove, L.E. [Istituto Nazionale per la Fisica della Materia, OGG, ILL Grenoble (France); Mondelli, C. [Istituto Nazionale per la Fisica della Materia, OGG, ILL Grenoble (France); Alianelli, L. [Istituto Nazionale per la Fisica della Materia, OGG, ILL Grenoble (France); Institut Laue Langevin, Grenoble (France); Labbe-Lavigne, S. [CNRS, Grenoble (France); Natali, F. [Istituto Nazionale per la Fisica della Materia, OGG, ILL Grenoble (France); Bee, M. [Universite Joseph Fourier, Grenoble (France); Deriu, A. [Istituto Nazionale per la Fisica della Materia, Unita di Parma (Italy); Dipartimento di Fisica, Universita di Parma (Italy)

    2005-06-01

    We present new McStas simulations of the back-scattering thermal neutron spectrometer IN13 to evaluate the advantages of a new temperature gradient monochromator relative to a conventional one. The simulations show that a flux gain up to a factor 7 can be obtained with just a 10% loss in energy resolution and a 20% increase in beam spot size at the sample. The results also indicate that a moderate applied temperature gradient ({delta}T{approx}16K) is sufficient to obtain this significant flux gain. n.

  1. Characterization of Rayleigh backscattering arising in various two-mode fibers.

    Science.gov (United States)

    Yu, Dawei; Fu, Songnian; Cao, Zizheng; Tang, Ming; Deng, Lei; Liu, Deming; Giles, Ian; Koonen, Ton; Okonkwo, Chigo

    2016-05-30

    We experimentally characterize the mode dependent characteristics of Rayleigh backscattering (RB) arising in various two-mode fibers (TMFs). With the help of an all-fiber photonic lantern, we are able to measure the RB power at individual modes. Consequently, mode dependent power distribution of RB light caused by arbitrary forward propagation mode superposition can be obtained. The total RB power of the TMFs under test is higher than that of single mode fiber by at least 2 dB over the C band. Meanwhile, the RB light occurs among all guided modes in the TMFs with specific power ratios. The experimental characterization agrees well with the theoretical calculations.

  2. The detection of landmines by neutron backscattering: Exploring the limits of the technique

    Energy Technology Data Exchange (ETDEWEB)

    Viesti, G. [Dipartimento di Fisica dell' Universita di Padova and INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy)]. E-mail: giuseppe.viesti@pd.infn.it; Lunardon, M. [Dipartimento di Fisica dell' Universita di Padova and INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [Dipartimento di Fisica dell' Universita di Padova and INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Barbui, M. [INFN, Laboratori Nazionali di Legnaro, Viale dell' Universita 2, I-35020 Legnaro, Padova (Italy); Cinausero, M. [INFN, Laboratori Nazionali di Legnaro, Viale dell' Universita 2, I-35020 Legnaro, Padova (Italy); D' Erasmo, G. [Dipartimento di Fisica dell' Universita di Bari and INFN Sezione di Bari, Via E. Orabona 4, I-70126 Bari (Italy); Palomba, M. [Dipartimento di Fisica dell' Universita di Bari and INFN Sezione di Bari, Via E. Orabona 4, I-70126 Bari (Italy); Pantaleo, A. [Dipartimento di Fisica dell' Universita di Bari and INFN Sezione di Bari, Via E. Orabona 4, I-70126 Bari (Italy); Obhodas, J. [Department of Experimental Physics, Ruder Boskovic Institute, Bijenicka c.54, 10000 Zagreb (Croatia); Valkovic, V. [Department of Experimental Physics, Ruder Boskovic Institute, Bijenicka c.54, 10000 Zagreb (Croatia)

    2006-06-15

    Neutron backscattering (NB) sensors have been proposed for Humanitarian De-mining applications. Recently, a prototype hand-held system integrating a NB sensor in a metal detector has been developed within the EU-funded DIAMINE Project. The results obtained in terms of performance of the NB systems and limitations in its use are presented in this work. It is found that the performance of NB sensors is strongly limited by the presence of the soil moisture and by its small-scale variations. The use of the neutron hit distribution to reduce false alarms is explored.

  3. Theoretical analysis on double Rayleigh backscattering noise in optical fibre Raman amplifiers and its suppression

    Institute of Scientific and Technical Information of China (English)

    Jiang Wen-Ning; Chen Jian-Ping; Li Xin-Wan; Shang Tao

    2004-01-01

    In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fibre Raman amplifier is analysed. Expressions are presented for both forward pumping and backward pumping schemes. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The optimal position for the isolator is determined and is found to be insensitive to the power levels of the signals and pumps. The results show that a reduction of the DRB noise by almost 2 to 3 orders can be reached.

  4. Simulation study of x-ray backscatter imaging of pressure-plate improvised explosive devices

    Science.gov (United States)

    van den Heuvel, Johan; Fiore, Franco

    2012-06-01

    Improvised Explosive Devices (IEDs) triggered by pressure-plates are a serious threat in current theatres of operation. X-ray backscatter imaging (XBI) is a potential method for detecting buried pressure-plates. Monte-Carlo simulation code was developed in-house and has been used to study the potential of XBI for pressure-plate detection. It is shown that pressure-plates can be detected at depths up to 7 cm with high photon energies of 350 keV with reasonable speeds of 1 to 10 km/h. However, spatial resolution is relatively low due to multiple scattering.

  5. Investigating the spectral characteristics of backscattering from heterogeneous spheroidal nuclei using broadband finite-difference time-domain simulations

    Science.gov (United States)

    Chao, Guo-Shan; Sung, Kung-Bin

    2010-02-01

    Backscattered light spectra have been used to extract size distribution of cell nuclei in epithelial tissues for noninvasive detection of precancerous lesions. In existing experimental studies, size estimation is achieved by assuming nuclei as homogeneous spheres or spheroids and fitting the measured data with models based on Mie theory. However, the validity of simplifying nuclei as homogeneous spheres has not been thoroughly examined. In this study, we investigate the spectral characteristics of backscattering from models of spheroidal nuclei under plane wave illumination using three-dimensional finite-difference time-domain (FDTD) simulation. A modulated Gaussian pulse is used to obtain wavelength dependent scattering intensity with a single FDTD run. The simulated model of nuclei consists of a nucleolus and randomly distributed chromatin condensation in homogeneous cytoplasm and nucleoplasm. The results show that backscattering spectra from spheroidal nuclei have similar oscillating patterns to those from homogeneous spheres with the diameter equal to the projective length of the spheroidal nucleus along the propagation direction. The strength of backscattering is enhanced in heterogeneous spheroids as compared to homogeneous spheroids. The degree of which backscattering spectra of heterogeneous nuclei deviate from Mie theory is highly dependent on the distribution of chromatin/nucleolus but not sensitive to nucleolar size, refractive index fluctuation or chromatin density.

  6. Constraining the physical properties of Titan's empty lake basins using nadir and off-nadir Cassini RADAR backscatter

    Science.gov (United States)

    Michaelides, R. J.; Hayes, A. G.; Mastrogiuseppe, M.; Zebker, H. A.; Farr, T. G.; Malaska, M. J.; Poggiali, V.; Mullen, J. P.

    2016-05-01

    We use repeat synthetic aperture radar (SAR) observations and complementary altimetry passes acquired by the Cassini spacecraft to study the scattering properties of Titan's empty lake basins. The best-fit coefficients from fitting SAR data to a quasi-specular plus diffuse backscatter model suggest that the bright basin floors have a higher dielectric constant, but similar facet-scale rms surface facet slopes, to surrounding terrain. Waveform analysis of altimetry returns reveals that nadir backscatter returns from basin floors are greater than nadir backscatter returns from basin surroundings and have narrower pulse widths. This suggests that floor deposits are structurally distinct from their surroundings, consistent with the interpretation that some of these basins may be filled with evaporitic and/or sedimentary deposits. Basin floor deposits also express a larger diffuse component to their backscatter, which is likely due to variations in subsurface structure or an increase in roughness at the wavelength scale (Hayes, A.G. et al. [2008]. Geophys. Res. Lett. 35, 9). We generate a high-resolution altimetry radargram of the T30 altimetry pass over an empty lake basin, with which we place geometric constraints on the basin's slopes, rim heights, and depth. Finally, the importance of these backscatter observations and geometric measurements for basin formation mechanisms is briefly discussed.

  7. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    Science.gov (United States)

    Yu, Han; Huang, Yunsong; Guo, Bowen

    2016-07-01

    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, 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. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green's function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  8. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    KAUST Repository

    Yu, Han

    2016-04-26

    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, 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. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green\\'s function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  9. Evaluation of Four Supervised Learning Methods for Benthic Habitat Mapping Using Backscatter from Multi-Beam Sonar

    Directory of Open Access Journals (Sweden)

    Jacquomo Monk

    2012-11-01

    Full Text Available An understanding of the distribution and extent of marine habitats is essential for the implementation of ecosystem-based management strategies. Historically this had been difficult in marine environments until the advancement of acoustic sensors. This study demonstrates the applicability of supervised learning techniques for benthic habitat characterization using angular backscatter response data. With the advancement of multibeam echo-sounder (MBES technology, full coverage datasets of physical structure over vast regions of the seafloor are now achievable. Supervised learning methods typically applied to terrestrial remote sensing provide a cost-effective approach for habitat characterization in marine systems. However the comparison of the relative performance of different classifiers using acoustic data is limited. Characterization of acoustic backscatter data from MBES using four different supervised learning methods to generate benthic habitat maps is presented. Maximum Likelihood Classifier (MLC, Quick, Unbiased, Efficient Statistical Tree (QUEST, Random Forest (RF and Support Vector Machine (SVM were evaluated to classify angular backscatter response into habitat classes using training data acquired from underwater video observations. Results for biota classifications indicated that SVM and RF produced the highest accuracies, followed by QUEST and MLC, respectively. The most important backscatter data were from the moderate incidence angles between 30° and 50°. This study presents initial results for understanding how acoustic backscatter from MBES can be optimized for the characterization of marine benthic biological habitats.

  10. Detecting changes in ultrasound backscattered statistics by using Nakagami parameters: Comparisons of moment-based and maximum likelihood estimators.

    Science.gov (United States)

    Lin, Jen-Jen; Cheng, Jung-Yu; Huang, Li-Fei; Lin, Ying-Hsiu; Wan, Yung-Liang; Tsui, Po-Hsiang

    2017-02-09

    The Nakagami distribution is an approximation useful to the statistics of ultrasound backscattered signals for tissue characterization. Various estimators may affect the Nakagami parameter in the detection of changes in backscattered statistics. In particular, the moment-based estimator (MBE) and maximum likelihood estimator (MLE) are two primary methods used to estimate the Nakagami parameters of ultrasound signals. This study explored the effects of the MBE and different MLE approximations on Nakagami parameter estimations. Ultrasound backscattered signals of different scatterer number densities were generated using a simulation model, and phantom experiments and measurements of human liver tissues were also conducted to acquire real backscattered echoes. Envelope signals were employed to estimate the Nakagami parameters by using the MBE, first- and second-order approximations of MLE (MLE1 and MLE2, respectively), and Greenwood approximation (MLEgw) for comparisons. The simulation results demonstrated that, compared with the MBE and MLE1, the MLE2 and MLEgw enabled more stable parameter estimations with small sample sizes. Notably, the required data length of the envelope signal was 3.6 times the pulse length. The phantom and tissue measurement results also showed that the Nakagami parameters estimated using the MLE2 and MLEgw could simultaneously differentiate various scatterer concentrations with lower standard deviations and reliably reflect physical meanings associated with the backscattered statistics. Therefore, the MLE2 and MLEgw are suggested as estimators for the development of Nakagami-based methodologies for ultrasound tissue characterization.

  11. Enhancement of phonon backscattering due to confinement of ballistic phonon pathways in silicon as studied with a microfabricated phonon spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Otelaja, O. O. [School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 (United States); Robinson, R. D., E-mail: rdr82@cornell.edu [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2015-10-26

    In this work, the mechanism for enhanced phonon backscattering in silicon is investigated. An understanding of phonon propagation through substrates has implications for engineering heat flow at the nanoscale, for understanding sources of decoherence in quantum systems, and for realizing efficient phonon-mediated particle detectors. In these systems, phonons that backscatter from the bottom of substrates, within the crystal or from interfaces, often contribute to the overall detector signal. We utilize a microscale phonon spectrometer, comprising superconducting tunnel junction emitters and detectors, to specifically probe phonon backscattering in silicon substrates (∼500 μm thick). By etching phonon “enhancers” or deep trenches (∼90 μm) around the detectors, we show that the backscattered signal level increases by a factor of ∼2 for two enhancers versus one enhancer. Using a geometric analysis of the phonon pathways, we show that the mechanism of the backscattered phonon enhancement is due to confinement of the ballistic phonon pathways and increased scattering off the enhancer walls. Our result is applicable to the geometric design and patterning of substrates that are employed in phonon-mediated detection devices.

  12. Backscattered electron imaging at low emerging angles: A physical approach to contrast in LVSEM

    Energy Technology Data Exchange (ETDEWEB)

    Cazaux, J., E-mail: jacques.cazaux@univ-reims.fr [LISM, EA 4695 Faculty of Sciences, BP 1039, 51687 Reims Cedex 2 (France); Kuwano, N. [Malaysia–Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Sato, K. [Steel Research Laboratory, JFE Steel Corporation, 1 Kawasaki-cho, Chuo-ku, Chiba 260-0835 (Japan)

    2013-12-15

    Due to the influence of refraction effects on the escape probability of the Back-Scattered Electrons (BSE), an expression of the fraction of these BSE is given as a function of the beam energy, E°, and emission angle (with respect to the normal) α. It has been shown that these effects are very sensitive to a local change of the work function in particular for low emerging angles. This sensitivity suggests a new type of contrast in Low Voltage Scanning Electron Microscopy (LVSEM for E°<2 keV): the work function contrast. Involving the change of ϕ with crystalline orientation, this possibility is supported by a new interpretation of a few published images. Some other correlated contrasts are also suggested. These are topographical contrasts or contrasts due to subsurface particles and cracks. Practical considerations of the detection system and its optimization are indicated. - Highlights: • Refraction effects experienced by Back-Scattered Electrons at sample/vacuum interfaces are evaluated as a function of energy and angles. • Sensitive to local work function changes with crystalline orientation these effects concern mainly keV-electrons at low emerging angles. • A new type of contrast in SEM is thus deduced and illustrated. • Some other correlated contrasts, topographical contrasts or contrasts due to subsurface particles and cracks are also suggested.

  13. Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR).

    Science.gov (United States)

    Wagner, Wolfgang; Pathe, Carsten; Doubkova, Marcela; Sabel, Daniel; Bartsch, Annett; Hasenauer, Stefan; Blöschl, Günter; Scipal, Klaus; Martínez-Fernández, José; Löw, Alexander

    2008-02-21

    The high spatio-temporal variability of soil moisture is the result of atmosphericforcing and redistribution processes related to terrain, soil, and vegetation characteristics.Despite this high variability, many field studies have shown that in the temporal domainsoil moisture measured at specific locations is correlated to the mean soil moisture contentover an area. Since the measurements taken by Synthetic Aperture Radar (SAR)instruments are very sensitive to soil moisture it is hypothesized that the temporally stablesoil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT AdvancedSynthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located inthe Duero basin, Spain. It is found that a time-invariant linear relationship is well suited forrelating local scale (pixel) and regional scale (50 km) backscatter. The observed linearmodel coefficients can be estimated by considering the scattering properties of the terrainand vegetation and the soil moisture scaling properties. For both linear model coefficients,the relative error between observed and modelled values is less than 5 % and thecoefficient of determination (R²) is 86 %. The results are of relevance for interpreting anddownscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT)and passive (SMOS, AMSR-E) instruments.

  14. Specific absorption and backscatter coefficient signatures in southeastern Atlantic coastal waters

    Science.gov (United States)

    Bostater, Charles R., Jr.

    1998-12-01

    Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.

  15. An open-source engine for the processing of electron backscatter patterns: EBSD-image.

    Science.gov (United States)

    Pinard, Philippe T; Lagacé, Marin; Hovington, Pierre; Thibault, Denis; Gauvin, Raynald

    2011-06-01

    An open source software package dedicated to processing stored electron backscatter patterns is presented. The package gives users full control over the type and order of operations that are performed on electron backscatter diffraction (EBSD) patterns as well as the results obtained. The current version of EBSD-Image (www.ebsd-image.org) offers a flexible and structured interface to calculate various quality metrics over large datasets. It includes unique features such as practical file formats for storing diffraction patterns and analysis results, stitching of mappings with automatic reorganization of their diffraction patterns, and routines for processing data on a distributed computer grid. Implementations of the algorithms used in the software are described and benchmarked using simulated diffraction patterns. Using those simulated EBSD patterns, the detection of Kikuchi bands in EBSD-Image was found to be comparable to commercially available EBSD systems. In addition, 24 quality metrics were evaluated based on the ability to assess the level of deformation in two samples (copper and iron) deformed using 220 grit SiC grinding paper. Fourteen metrics were able to properly measure the deformation gradient of the samples.

  16. Validation of neutron texture data on GEM at ISIS using electron backscattered diffraction

    Science.gov (United States)

    Davies, Peter; Kockelmann, Winfried; Wynne, Brad; Eccleston, Roger; Hutchinson, Bevis; Rainforth, W. Mark

    2008-03-01

    The high solid angular coverage of the general materials (GEM) diffractometer at the ISIS pulsed neutron source located at the UK Rutherford Appleton Laboratory offers the capability of obtaining quantitative bulk crystallographic texture data in a 'single shot' within a matter of minutes. This enables the possibility of in situ texture measurements to be made as a function of temperature to monitor and quantify texture changes during phase transformation or microstructure restoration processes like recrystallization. The purpose of this paper is to determine the quality of the texture data produced from GEM in order to define a level of confidence for subsequent texture model validation. This has been achieved by comparing textures of sections of a 200 mm diameter titanium alloy billet using data obtained from GEM with data obtained using electron backscattered diffraction (EBSD). In both cases, the data were obtained at room temperature. EBSD, unlike time-of-flight neutron diffraction analysis, obtains texture data directly from orientation measurements via backscattered Kikuchi patterns in the scanning electron microscope. In all analysed locations, both methods show near-identical textures, with regard to both the general orientation distributions and the levels of intensity of the distributions. This shows that the GEM diffractometer is capable of accurately determining bulk textures in a single shot, thus confirming its suitability for in situ high temperature experiments.

  17. Transparency Effect of Electrolyte on Light Back-Scattering in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    N. Sharifi

    2015-12-01

    Full Text Available Conventionally, a film of TiO2 particles of ~300 nm size is employed in DSCs as the back reflector film to enhance the light harvesting. In this study, two electrolytes with different transparencies, iodide-based and cobalt-based electrolytes, were used to investigate the transparency effect of electrolytes on light back-scattering from back scattering layer and also to study its effect on the performance of DSCs. The use of cobalt-based electrolyte is recommended from the view point of optical properties as due to the light absorption in electrolytes, the current density losses are 2.9mA/cm2 and 4.2 mA/cm2 in cobalt- and iodide-based electrolytes, respectively, and the transmission of 100% is observed for cobalt-based electrolyte in 500-600 nm in spite of iodide-based electrolyte. Use of light back-scattering layer, unlike iodide-based cell, causes external quantum efficiency in cobalt-base cell to increase for the wavelengths lower than 350 nm since cobalt-base electrolyte has transparency in this region. In addition, optical calculations demonstrate that in the range 400-500 nm, in which dye has a noticeable absorption, absorption loss is 40% and 30% for iodide- and cobalt-based electrolytes, respectively.

  18. Noninvasive measurement of local thermal diffusivity using backscattered ultrasound and focused ultrasound heating.

    Science.gov (United States)

    Anand, Ajay; Kaczkowski, Peter J

    2008-09-01

    Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create a brief local temperature rise of no more than 10 degrees C. Beamformed radio-frequency (RF) data are collected during heating and cooling using a clinical ultrasound scanner. Measurements of the time-varying "acoustic strain", that is, spatiotemporal variations in the RF echo shifts induced by the temperature related sound speed changes, are related to a solution of the heat transfer equation to estimate the thermal diffusivity in the heated zone. Numerical simulations and experiments performed in vitro in tissue mimicking phantoms and excised turkey breast muscle tissue demonstrate agreement between the ultrasound derived thermal diffusivity estimates and independent estimates made by a traditional hot-wire technique. The new noninvasive ultrasonic method has potential applications in thermal therapy planning and monitoring, physiological monitoring and as a means of noninvasive tissue characterization.

  19. Backscatter and depolarization measurements of aerosolized biological simulants using a chamber lidar system

    Science.gov (United States)

    Brown, David M.; Thrush, Evan P.; Thomas, Michael E.; Santarpia, Josh; Quizon, Jason; Carter, Christopher C.

    2010-04-01

    To ensure agent optical cross sections are well understood from the UV to the LWIR, volume integrated measurements of aerosolized agent material at a few key wavelengths is required to validate existing simulations. Ultimately these simulations will be used to assess the detection performance of various classes of lidar technology spanning the entire range of the optical spectrum. The present work demonstrates an optical measurement architecture based on lidar allowing the measurement of backscatter and depolarization ratio from biological aerosols released in a refereed, 1-m cubic chamber. During 2009, various upgrades have been made to the chamber LIDAR system, which operates at 1.064 μm with sub nanosecond pulses at a 120 Hz repetition rate. The first build of the system demonstrated a sensitivity of aerosolized Bacillus atrophaeus (BG) on the order of 5×105 ppl with 1 GHz InGaAs detectors. To increase the sensitivity and reduce noise, the InGaAs detectors were replaced with larger-area silicon avalanche photodiodes for the second build of the system. In addition, computer controlled step variable neutral density filters are now incorporated to facilitate calibrating the system for absolute back-scatter measurements. Calibrated hard target measurements will be combined with data from the ground truth instruments for cross-section determination of the material aerosolized in the chamber. Measured results are compared to theoretical simulations of cross-sections.

  20. Basic study for ultrasound-based navigation for pedicle screw insertion using transmission and backscattered methods.

    Directory of Open Access Journals (Sweden)

    Ziqiang Chen

    Full Text Available The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation in spinal fusion surgery. Fourteen human vertebral specimens were disarticulated from seven un-embalmed cadavers (four males, three females, 73.14 ± 9.87 years, two specimens from each cadaver. Seven specimens were used to measure the transmission, including tests of attenuation and phase velocity, while the other seven specimens were used for backscattered measurements to inspect the depth of penetration and A-Mode signals. Five pairs of unfocused broadband ultrasonic transducers were used for the detection, with center frequencies of 0.5 MHz, 1 MHz, 1.5 MHz, 2.25 MHz, and 3.5 MHz. As a result, good and stable results were documented. With increased frequency, the attenuation increased (P0.05. At about 0.6 cm away from the cortical bone, warning signals were easily observed from the backscattered measurements. In conclusion, the ultrasonic system proved to be an effective, moveable, and real-time imaging navigation system. However, how ultrasonic navigation will benefit pedicle screw insertion in spinal surgery needs to be determined. Therefore, ultrasound-guided pedicle screw implantation is theoretically effective and promising.

  1. Determination of quality parameters in apple `Smoothee Golden Delicious' using backscattering laser imaging

    Science.gov (United States)

    Lafuente, Victoria; Val, Jesús; Urzola, Concha; Negueruela, Ignacio

    2013-11-01

    The objective of this study was to evaluate in `Smoothee Golden Delicious' apples, the use of backscattering images as a non-destructive method to estimate some quality parameters during the ripening process of fruits. In this experiment, 208 apples were collected from an experimental orchard of the Estación Experimental de Aula Dei (CSIC) in Zaragoza (Northeastern, Spain). Backscattering images were kept from samples picked up every 15 days during 7 months until harvest. In the same fruits, soluble solids contents (SSC) and firmness were measured by traditional destructive methods. The light source was a solid state laser diode module emitting at three different spectral bands (670, 785 and 980 nm) PLS calibration methods were used to create the statistical model to predict SSC and firmness. Good results were obtained when PLS calibration was applied to Feret diameter corresponding at different levels of gray. The Rcv2 values were 0.87 for firmness and 0.93 for SSC, which are higher than other reported in the literature for the same commodity.

  2. Study on the backscattered light intensity to airborne laser range-gated imaging

    Science.gov (United States)

    Wang, Ling; Yu, Lei; Kou, Tian; Wu, Xueming

    2016-10-01

    Based on the range-gated technology in the application of airborne laser detection imaging system, sequence relations of the parameters in the model of range gating in detail was analyzed. The effective scope of atmospheric backscatter and the moment before or after pulsing of the unit section was obtained. Horizontal range-gated imaging model was established and the calculation method of backscattered light intensity was given. Then slant distance detection of airborne laser active imaging was revised. By the object-image relation of points on the scattering section, the light path diagram of imaging detection system was built and the corresponding relation of light intensity between scattering points and receiving points was given. The variation regularity and distribution of light intensity on the detector under horizontal and slant detection were gained. Under the idea, the outfield testing platform was set up, and the relative error of data between measured and simulated results was controlled within 5%. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model.

  3. Multibeam volume acoustic backscatter imagery and reverberation measurements in the northeastern Gulf of Mexico

    Science.gov (United States)

    Gallaudet, Timothy C.; deMoustier, Christian P.

    2002-08-01

    Multibeam volume acoustic backscatter imagery and reverberation measurements are derived from data collected in 200-m-deep waters in the northeastern Gulf of Mexico, with the Toroidal Volume Search Sonar (TVSS), a 68-kHz cylindrical sonar operated by the U.S. Navy's Coastal System Station. The TVSS's 360-degree vertical imaging plane allows simultaneous identification of multiple volume scattering sources and their discrimination from backscatter at the sea surface or the seafloor. This imaging capability is used to construct a three-dimensional representation of a pelagic fish school near the bottom. Scattering layers imaged in the mixed layer and upper thermocline are attributed to assemblages of epipelagic zooplankton. The fine scale patchiness of these scatterers is assessed with the two-dimensional variance spectra of vertical volume scattering strength images in the upper and middle water column. Mean volume reverberation levels exhibit a vertical directionality which is attributed to the volume scattering layers. Boundary echo sidelobe interference and reverberation is shown to be the major limitation in obtaining bioacoustic data with the TVSS. Because net tow and trawl samples were not collected with the acoustic data, the analysis presented is based upon comparison to previous biologic surveys in the northeastern Gulf of Mexico and reference to the bioacoustic literature. copyright 2002 Acoustical Society of America.

  4. Imaging near-surface heterogeneities by natural migration of backscattered surface waves: Field data test

    KAUST Repository

    Liu, Zhaolun

    2017-03-06

    We have developed a methodology for detecting the presence of near-surface heterogeneities by naturally migrating backscattered surface waves in controlled-source data. The near-surface heterogeneities must be located within a depth of approximately one-third the dominant wavelength λ of the strong surface-wave arrivals. This natural migration method does not require knowledge of the near-surface phase-velocity distribution because it uses the recorded data to approximate the Green’s functions for migration. Prior to migration, the backscattered data are separated from the original records, and the band-passed filtered data are migrated to give an estimate of the migration image at a depth of approximately one-third λ. Each band-passed data set gives a migration image at a different depth. Results with synthetic data and field data recorded over known faults validate the effectiveness of this method. Migrating the surface waves in recorded 2D and 3D data sets accurately reveals the locations of known faults. The limitation of this method is that it requires a dense array of receivers with a geophone interval less than approximately one-half λ.

  5. Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave-current coupled model

    Science.gov (United States)

    Tao, Xie; Shang-Zhuo, Zhao; William, Perrie; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-06-01

    To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave-current model is derived, based on the mechanism of wave-current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave-current interaction effect of the ocean current is much stronger than that of the nonlinear wave-wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service.

  6. Performance of Dynamically Simulated Reference Patterns for Cross-Correlation Electron Backscatter Diffraction.

    Science.gov (United States)

    Jackson, Brian E; Christensen, Jordan J; Singh, Saransh; De Graef, Marc; Fullwood, David T; Homer, Eric R; Wagoner, Robert H

    2016-08-01

    High-resolution (or "cross-correlation") electron backscatter diffraction analysis (HR-EBSD) utilizes cross-correlation techniques to determine relative orientation and distortion of an experimental electron backscatter diffraction pattern with respect to a reference pattern. The integrity of absolute strain and tetragonality measurements of a standard Si/SiGe material have previously been analyzed using reference patterns produced by kinematical simulation. Although the results were promising, the noise levels were significantly higher for kinematically produced patterns, compared with real patterns taken from the Si region of the sample. This paper applies HR-EBSD techniques to analyze lattice distortion in an Si/SiGe sample, using recently developed dynamically simulated patterns. The results are compared with those from experimental and kinematically simulated patterns. Dynamical patterns provide significantly more precision than kinematical patterns. Dynamical patterns also provide better estimates of tetragonality at low levels of distortion relative to the reference pattern; kinematical patterns can perform better at large values of relative tetragonality due to the ability to rapidly generate patterns relating to a distorted lattice. A library of dynamically generated patterns with different lattice parameters might be used to achieve a similar advantage. The convergence of the cross-correlation approach is also assessed for the different reference pattern types.

  7. Improved backscatter x-ray detection for anti-terrorist applications

    Energy Technology Data Exchange (ETDEWEB)

    Shope, S.L.; Lockwood, G.J.; Selph, M.M.; Wehlburg, J.C.

    1999-12-01

    Currently the most common method to determine the contents of a package suspected of containing an explosive device is to use transmission radiography. This technique requires that an x-ray source and film be placed on opposite sides of the package. This poses a problem if the package is placed so that only one side is accessible, such as against a wall. There is also a threat to personnel and property since explosive devices may be booby trapped. The authors have developed a method to x-ray a package using backscattered x-rays based on similar work for landmine detection. This procedure eliminates the use of film behind the target. All of the detection is done from the same side as the source. Backscatter experiments at Sandia National Laboratories have been conducted on mock bombs in packages. They are able to readily identify the bomb components. The images that are obtained in this procedure are done in real time and the image is displayed on a computer screen. Preliminary experiments have also imaged objects within or behind a wall. They are currently using a scanning x-ray source and scintillating plastic detectors. It can take several hours to image a briefcase size object. This time could be reduced if better x-ray detection methods could be used. They have looked at using pinhole photography and CCD cameras to reduce this time.

  8. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Directory of Open Access Journals (Sweden)

    M. Proksch

    2015-08-01

    Full Text Available The Microwave Emission Model of Layered Snowpacks (MEMLS was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like- and cross-polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS is set up in a way that snow input parameters can be derived by objective measurement methods which avoid fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx (Nordic Snow Radar Experiment campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in Matlab and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  9. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Directory of Open Access Journals (Sweden)

    M. Proksch

    2015-03-01

    Full Text Available The Microwave Emission Model of Layered Snowpacks (MEMLS was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like and cross polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS is set up in a way that snow input parameters can be derived by objective measurement methods which avoids fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in MATLAB and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  10. Lowering the risk of stimulated Brillouin backscatter from NIF hohlraums by re-pointing beams

    Science.gov (United States)

    Berger, Richard; Baker, K. L.; Thomas, C. A.; Milovich, J. L.; Langdon, A. B.; Strozzi, D. J.; Michel, M.

    2015-11-01

    The 64 beams that make a 50 degree angle with the hohlraum axis have been measured to reflect by Stimulated Brillouin Backscatter (SBS) enough laser light to cause optical damage and limit design parameter space. The amount of backscatter has been seen to depend on the initial plasma density filling the hohlraum, the hohlraum wall material, and the laser pulse length. The most important parameter causing SBS is the laser intensity on the hohlraum wall. In previous hohlraum designs, the intensity of the 50 degree beams has been controlled by cross-beam energy transfer (CBET). [P. Michel et al., Phys. Rev. Lett. 102, 025004 (2009)] Recent designs with reduced CBET have experienced an increase in SBS. Here we show that repointing beams can reduce the laser intensity at the wall and still maintain good beam smoothing. The reduction in intensity is achieved by separating the 44 and 50 degree cones of beams along the hohlraum axis and then repointing beams within each cone to reduce overlap while preserving polarization smoothing. PF3D simulations show dramatic reductions of SBS are possible. Experiments will determine whether increased laser entrance hole sizes will be required and whether this technique will open up new design options. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  11. Characterization of the hot electron population with bremsstrahlung and backscatter measurements at the National Ignition Facility

    Science.gov (United States)

    Albert, Felicie; Hohenberger, Matthias; Michel, Pierre; Divol, Laurent; Doeppner, Tilo; Dewald, Edward; Bachmann, Benjamin; Ralph, Joseph; Turnbull, David; Goyon, Clement; Thomas, Cliff; Landen, Otto; Moody, John

    2016-10-01

    In indirect-drive ignition experiments, the hot electron population, produced by laser-plasma interactions, can be inferred from the bremsstrahlung generated by the interaction of the hot electrons with the target. At the National Ignition Facility (NIF), the upgraded filter-fluorescer x-ray diagnostic (FFLEX), a 10-channel, time-resolved hard x-ray spectrometer operating in the 20- to 500-keV range, provides measurements of the bremsstrahlung spectrum. It typically shows a two-temperature distribution of the hot electron population inside the hohlraum. In SRS, where the laser is coupled to an electron plasma wave, the backscattered spectrum, measured with the NIF full-aperture backscatter system (FABS), is used to infer the plasma wave phase velocity. We will present FFLEX time-integrated and time-resolved measurements of the hot electron population low-temperature component. We will correlate them with electron plasma wave phase velocities inferred from FABS spectra for a range of recent shots performed at the National Ignition Facility. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. Study on electromagnetic backscattering and Doppler spectrum of a moving spherical target above time-varying sea surface

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The surface electric current of the sea surface and the first-order scattering field from the spherical target were obtained by employing Physical Optics method and Mie theory,respectively. The backscattering field of the time-evolving sea surface was calculated by using Kirchhoff Approximation. Meanwhile,by taking the ad-vantage of a newly developed technique that utilizes the reciprocity theorem,the difficulty in formulating the secondary coupling scattering fields from the spherical target above the sea surface was reduced. The dependence of the secondary cou-pling backscattering field on the size and the position of the spherical target was discussed,and the characteristic of the Doppler spectrum of the composite back-scattering field with different incident angles was analyzed in detail.

  13. Comparing surficial sediments maps interpreted by experts with dual-frequency acoustic backscatter on the Scotian Shelf, Canada

    Science.gov (United States)

    Cuff, Andrew; Anderson, John T.; Devillers, Rodolphe

    2015-11-01

    Understanding seabed properties is increasingly important to support policy in the marine environment. Such knowledge can be gained from diverse methods, ranging from more traditional expert-interpretations of acoustic and ground-truth data, to maps resulting from fully quantitative analyses of acoustic data. This study directly compares surficial geology maps created through expert-interpretations to near-nadir acoustic backscatter data from two frequencies (38 kHz and 120 kHz) collected using single beam echosounders (SBES) for two 5×1 km study areas on the Scotian Shelf, Canada. Statistical methods were used to analyze and classify both single and dual-frequency acoustic backscatter for comparisons. In particular, spatial scaling of acoustic backscatter responses and acoustic classes created using acoustic seabed classification (ASC) is compared between frequencies and to interpreted sediment units (ISUs) which make up surficial geology maps produced by experts. Seabed morphology layers were included in an ASC approach to reflect the morphological components included in the interpreted geological maps. Results confirmed that higher frequencies and coarser grain sizes generally produced higher backscatter, while more heterogeneous and rougher seabeds produced variable backscatter. Differing acoustic responses within similar substrate units suggest fundamental seabed variations not reflected in the geological interpretations. Spatial scaling of sand and gravel substrates from 38 kHz frequency were closer than the 120 kHz frequency to the spatial scaling of the interpreted geological map. Variable grain size in the sediment volume and surface morphology are both presented as possible reasons for frequency differences. While both frequencies had similar general responses, differences in frequency responses of backscatter occurred at scales of tens to hundreds of meters. Results presented here emphasize the importance of multi-scale seabed mapping and additional

  14. Analytical Model of Doppler Spectra of Light Backscattered from Rotating Convex Bodies of Revolution in the Global Cartesian Coordinate System

    Institute of Scientific and Technical Information of China (English)

    GONG Yan-Jun; WU Zhen-Sen; WU Jia-Ji

    2009-01-01

    We present an analytical model of Doppler spectra in backscattering from arbitrary rough convex bodies of revolution rotating around their axes in the global Cartesian coordinate system. This analytical model is applied to analyse Doppler spectra in backscatter from two cones and two cylinders, as well as two ellipsoids of revolution. We numerically analyse the influences of attitude and geometry size of objects on Doppler spectra. The analytical model can give contribution of the surface roughness, attitude and geometry size of convex bodies of revolution to Doppler spectra and may contribute to laser Doppler velocimetry as well as ladar applications.

  15. Sub-Doppler resonances in the back-scattered light from random porous media infused with Rb vapor

    CERN Document Server

    Villalba, S; Lenci, L; Bloch, D; Lezama, A; Failache, H

    2013-01-01

    We report on the observation of sub-Doppler resonances on the back-scattered light from a random porous glass medium with rubidium vapor filling its interstices. The sub-Doppler spectral lines are the consequence of saturated absorption where the incident laser beam saturates the atomic medium and the back-scattered light probes it. Some specificities of the observed spectra reflect the transient atomic evolution under confinement inside the pores. Simplicity, robustness and potential miniaturization are appealing features of this system as a spectroscopic reference.

  16. The soil moisture and its effect on the detection of buried hydrogenous material by neutron backscattering technique

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei Ochbelagh, D. [Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil (Iran, Islamic Republic of)], E-mail: ddrezaey@yahoo.com; Miri Hakimabad, H.; Izadi Najafabadi, R. [Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2009-05-15

    Among the available nuclear techniques, the neutron backscattering technique, based on the detection of the produced thermal neutrons, is thought to be the most promising for landmine detections. The results obtained from Monte Carlo simulation were used for selection of BF{sub 3} detector and Am-Be neutron source shielding. In addition, soil moisture was discussed as a limitation of the neutron backscattering technique. It was experimentally found that this technique is useful for soil whose water content is lower than 14%.

  17. Backscattering and vegetation water content response of paddy crop at C-band using RISAT-1 satellite data

    Science.gov (United States)

    Kumar, Pradeep; Prasad, Rajendra; Choudhary, Arti; Gupta, Dileep Kumar; Narayan Mishra, Varun; Srivastava, Prashant K.

    2016-04-01

    The study about the temporal behaviour of vegetation water content (VWC) is essential for monitoring the growth of a crop to improve agricultural production. In agriculture, VWC could possibly provide information that can be used to infer water stress for irrigation decisions, vegetation health conditions, aid in yield estimation and assessment of drought conditions (Penuelas et al., 1993). The VWC is an important parameter for soil moisture retrieval in microwave remote sensing (Srivastava et al., 2014). In the present study, the backscattering and VWC response of paddy crop has been investigated using medium resolution (MRS) radar imaging satellite-1 (RISAT-1) synthetic aperture radar (SAR) data in Varanasi, India. The VWC of paddy crop was measured at its five different growth stages started from 15 July 2013 to 23 October 2013 from the transplanting to maturity stage during Kharif season. The whole life of paddy crop was divided into three different major growth stages like vegetative stage, reproductive stage and ripening stage. During vegetative stage, the backscattering coefficients were found increasing behaviour until the leaves became large and dense due to major contribution of stems and the interaction between the stems and water underneath the paddy crop. During reproductive stage, the backscattering coefficients were found to increase slowly due to random scattering by vertical leaves. The increase in the size of leaves cause to cover most of the spaces between plants resulted to quench the contributions from the stems and the water underneath. At the maturity stage, the backscattering showed its decreasing behaviour. The VWC of paddy crop was found increasing up to vegetative to reproductive stages (28 September 2013) and then started decreasing during the ripening (maturity) stage. Similar behaviour was obtained between backscattering coefficients and VWC that showed an increasing trend from vegetative to reproductive stage and then lowering down at

  18. Real-Time Bathymetry and Backscatter Mosaic Software for Towed and Shipboard Mapping Sonars

    Science.gov (United States)

    Davis, R. B.; Appelgate, T. B.; Johnson, P. D.

    2006-12-01

    The Hawaii Mapping Research Group (HMRG) of the University of Hawaii has developed a bathymetry and backscatter mosaic software package that is suitable for use either in real-time survey operations or non-real- time processing applications. The system was originally developed for use with HMRG's own towed sonar systems but is also compatible with shipboard multibeam systems. It has been operational on R/V Kilo Moana under the supervision of the University's Ocean Technology Group marine science technicians for well over a year in support of that vessel's Kongsberg/Simrad EM120 and EM1002 multibeams. The software grids and renders incoming data in geo-referenced chart-like displays. Data are typically processed in three operator-selectable resolutions limited only by the processing and storage capabilities of the Linux- or Unix-based host computer system. A master navigation chart shows survey tracklines and swath coverage -- from this chart the user can simultaneously open multiple mosaic views into the underlying bathymetry and backscatter datasets with independent resolutions and display properties (e.g., contour color key and interval for bathymetry, grayscale mapping for backscatter, region of interest, etc.) All displays are optimized for quick pan and zoom operations and include on-screen interface control features which permit numerous display parameters to be rapidly changed. All mosaic views, as well as the master navigation display, can be updated in real-time as new data are supplied by the mapping instrument and can also display a background reference dataset for comparison with incoming instrument data. The software also includes survey-planning features which permit new survey waypoints to be generated interactively with reference to incoming and/or historical background data. Aboard R/V Kilo Moana a pair of dual-monitor computer systems, one for the EM120 and one for the EM1002, are available for the processing and display of incoming data from

  19. Characteristics of aerosol size distribution and vertical backscattering coefficient profile during 2014 APEC in Beijing

    Science.gov (United States)

    Zhang, Jiaoshi; Chen, Zhenyi; Lu, Yihuai; Gui, Huaqiao; Liu, Jianguo; Liu, Wenqing; Wang, Jie; Yu, Tongzhu; Cheng, Yin; Chen, Yong; Ge, Baozhu; Fan, Yu; Luo, Xisheng

    2017-01-01

    During the 2014 Asia-Pacific Economic Cooperation (APEC) conference period, Beijing's air quality was greatly improved as a result of a series of tough emission control measures being implemented in Beijing and its surrounding provinces. However, a moderate haze occurred during the period of 4-5 November. In order to evaluate the emission control measures and study the formation mechanism of the haze, a comprehensive field observation based on a supersite and a lidar network was carried out from 25 October 2014 to 20 January 2015. By investigating the variations in aerosol number concentration and mean backscattering coefficient before, during and after the APEC period, it was found that number concentration of accumulation mode and coarse mode particles experienced the most significant decrease by 47% and 68%, and mean backscattering coefficient below 1 km decreased by 34% during the APEC period. Being characterized as "rapidly accumulating and rapidly dispersing", the moderate haze occurred during the APEC period was probably initiated by a wind direction change to south and an increase of wind speed to 4 m/s. Sulfur dioxide involved plume nucleation without growth in size as well as a burst of particles ranging between 100 and 300 nm were observed simultaneously during the haze episode. The elevation of sulfur dioxide concentration and particle number concentration was highly correlated with the southerly wind, signifying the contribution of regional transport. It was observed by the lidar network that the aerosol backscattering coefficient increased in sequence among three sites along the southwest pathway, suggesting that aerosols might be transported from the southwest to the northeast of Beijing with a speed of approximately 17 km/h, which agreed with the movement of air masses modeled by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). The dual-wavelength lidar (355 and 532 nm) observation suggested that transportation of fine particles

  20. Monitoring spatial and temporal variations of the rice backscatter coefficient (σ0) at different phenological stages in Sungai Burong and Sawah Sempadan, Kuala Selangor.

    Science.gov (United States)

    Aishah Mohd Rasit, Siti; Shariff, Abdul Rashid Mohammed; Razak, Janatul Aziera Abdul; Ghani, Aisyah Afiqah Abdul; Fikri Abdullah, Ahmad; Wayayok, Aimrun

    2016-06-01

    Monitoring rice growth and yield estimation using optical remote sensing data constitutes a big challenge largely due to cloud conditions that are typical of tropical regions. Using Radar remote sensing data helps because it overcomes the cloud issue and distinguishes the behaviour of the radar backscattering of rice crops specifically. This study indicated the temporal change of rice backscatter (σ°) at two different growth stages using HH polarimetric Radarsat-2. The aims of this study are: (1) to identify crop with different life spans based on the backscatter coefficient's values from a single polarisation for understanding the backscatter characteristic of rice over the entire growth cycle, and (2) to understand the advantages and limitations using the RADARSAT-2, C band with HH polarisation. The values of backscattering coefficients have been related to the Malaysia rice crop calendar to get the information of the growth status. The result shows strong backscatter coefficient values on the 21st of May that referred to the reproductive-maturity of rice in the Sawah Sempadan area, and out of season for the Sungai Burong area. While for the August 1st imagery, the result shows weak backscatter values which refers to early vegetative and vegetative-reproductive. The values of backscattering coefficient are found to be much less for early vegetation compare to mature rice crop. In this paper, we have also performed a classification of a rice field using Landsat 8 OLI.

  1. Use of Reciprocal Lattice Layer Spacing in Electron Backscatter Diffraction Pattern Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Eades, J.A.; Michael, J.R.

    1999-05-10

    In the scanning electron microscope (SEM), using electron backscattered diffraction (EBSD), it is possible to measure the spacing of the layers in the reciprocal lattice. These values are of great use in confirming the identification of phases. The technique derives the layer spacing from the HOLZ rings which appear in patterns from many materials. The method adapts results from convergent-beam electron diffraction (CBED) in the transmission electron microscope (TEM). For many materials the measured layer spacing compares well with the calculated layer spacing. A noted exception is for higher atomic number materials. In these cases an extrapolation procedure is described that requires layer spacing measurements at a range of accelerating voltages. This procedure is shown to improves the accuracy of the technique significantly. The application of layer spacing measurements in EBSD is shown to be of use for the analysis of two polytypes of SiC.

  2. Improved angular resolution in electron backscatter diffraction analysis by use of image correlation techniques

    Institute of Scientific and Technical Information of China (English)

    CUI HY; Andrew GODFREY; WANG W

    2008-01-01

    In this paper we describe a method for improving the angular resolution of the electron backscatter diffraction(EBSD)technique based on a correlative matching of EBSD patterns.Standard image interpolation methods are used to detect shifts between selected regions of the EBSD patterns to an accuracy of one tenth of a pixel.Simulated data sets are used to show that such accuracy,combined with a small angle approximation in calculation of the rotation angle,allows determination of the misorientation between patterns to an accuracy of 0.01 degrees.The method is tested on samples of both single crystal aluminum and recrystallized nickel.The results demonstrate the accuracy and stability of the new method compared to the conventional method.

  3. A Micropulse eye-safe all-fiber molecular backscatter coherent temperature lidar

    Directory of Open Access Journals (Sweden)

    Abari Cyrus F.

    2016-01-01

    Full Text Available In this paper, we analyze the performance of an all-fiber, micropulse, 1.5 μm coherent lidar for remote sensing of atmospheric temperature. The proposed system benefits from the recent advances in optics/electronics technology, especially an all-fiber image-reject homodyne receiver, where a high resolution spectrum in the baseband can be acquired. Due to the presence of a structured spectra resulting from the spontaneous Rayleigh-Brillouine scattering, associated with the relevant operating regimes, an accurate estimation of the temperature can be carried out. One of the main advantages of this system is the removal of the contaminating Mie backscatter signal by electronic filters at the baseband (before signal conditioning and amplification. The paper presents the basic concepts as well as a Monte-Carlo system simulation as the proof of concept.

  4. Multi-channel Doppler backscattering measurements in the C-2 field reversed configuration.

    Science.gov (United States)

    Schmitz, L; Ruskov, E; Deng, B H; Gota, H; Gupta, D; Tuszewski, M; Douglass, J; Peebles, W A; Binderbauer, M; Tajima, T

    2014-11-01

    A versatile heterodyne Doppler Backscattering (DBS) system is used to measure density fluctuation levels (in the wavenumber range kρs ≤ 50), and the toroidal E × B flow velocity in the C-2 Field-Reversed Configuration (FRC). Six tunable frequencies in three waveguide bands (26 GHz ≤ f ≤ 90 GHz) are launched using monostatic beam optics, via a quasi-optical beam combiner/polarizer and an adjustable parabolic focusing mirror (inside the vacuum enclosure) achieving Gaussian beam spot sizes of 3-5.5 cm at the X/O-mode cutoff. The DBS system covers plasma densities of 0.8 × 10(13) ≤ ne ≤ 1 × 10(14) cm(-3), and provides access to the FRC core (up to the field null) and across the FRC separatrix into the scrape-off layer plasma.

  5. Electron backscatter diffraction study of polycrystalline YBa 2Cu 3O 7- δ ceramics

    Science.gov (United States)

    Koblischka-Veneva, Anjela; Koblischka, Michael R.; Simon, Petra; Mücklich, Frank; Murakami, Masato

    2002-11-01

    The electron backscatter diffraction (EBSD) technique was applied to polycrystalline YBa 2Cu 3O 7- δ ceramics. To obtain good quality EBSD Kikuchi patterns on the ceramic superconductors, a new sample polishing route was established. Samples with and without KClO 3-doping were investigated; and the crystallographic orientations of the grains were analyzed using pole figures and EBSD orientation mapping. On the polycrystalline KClO 3-doped YBa 2Cu 3O 7- δ samples we found two major orientations (0 0 1) and (1 0 0) normal to the sample surface, while the undoped sample did not exhibit any orientation maxima. We ascribe this observation to the effect of a liquid phase due to the KClO 3-additive during the preparation process.

  6. Experimental observation of the strong influence of crystal orientation on Electron Rutherford Backscattering Spectra

    Science.gov (United States)

    Vos, Maarten; Aizel, Koceila; Winkelmann, Aimo

    2010-06-01

    In Electron Rutherford Backscattering Spectroscopy (ERBS) energetic electrons (in our case up to 40 keV) impinge on a target and one measures the energy of elastically scattered electrons. This energy depends on the mass of the scattering atom, due to the recoil effect. This technique thus provides information about the sample composition. For single crystals the interaction of the projectile electron with the crystal potential modifies the angular intensity distribution of the scattered electrons. This leads, for example, to the well-known Kikuchi patterns. Here we investigate if such modified angular distribution has any influence on the intensity ratio of the observed elastic peaks in ERBS. Dramatic effects are found. Implications of these observations for quantitative surface analysis using energetic electrons are discussed.

  7. Misorientations in [001] magnetite thin films studied by electron backscatter diffraction and magnetic force microscopy

    Science.gov (United States)

    Koblischka-Veneva, A.; Koblischka, M. R.; Wei, J. D.; Zhou, Y.; Murphy, S.; Mücklich, F.; Hartmann, U.; Shvets, I. V.

    2007-05-01

    Magnetite thin films grown on [001] oriented MgO substrates are analyzed by means of electron backscatter diffraction (EBSD) analysis and magnetic force microscopy in applied fields. The EBSD technique enables the crystallographic orientation of individual grains to be determined with a high spatial resolution up to 20nm on such ceramic samples. A high image quality of the recorded Kikuchi patterns was achieved enabling multiphase scans and high spatial resolution measurements. Upon annealing in air, the magnetic properties of the magnetite thin films were found to change considerably. Using the EBSD analysis, we find that misoriented grains remaining after the annealing step form small islands with a size of about 100nm. The size and distribution of these islands correspond well to the observations of antiferromagnetic pinning centers within the magnetic domain structures carried out by magnetic force microscopy on the same samples.

  8. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    Science.gov (United States)

    Wang, Xiaoqing; Chou, Kevin

    2017-02-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  9. Thin film depth profiling using simultaneous particle backscattering and nuclear resonance profiling

    Science.gov (United States)

    Barradas, N. P.; Mateus, R.; Fonseca, M.; Reis, M. A.; Lorenz, K.; Vickridge, I.

    2010-06-01

    We report an important extension to the DataFurnace code for Ion Beam Analysis which allows users to simultaneously and self-consistently analyse Rutherford (RBS) or non-Rutherford (EBS) elastic backscattering together with particle-induced gamma-ray (PIGE) spectra. We show that the code works correctly with a well-known sample. Previously it has not been feasible to self-consistently treat PIGE and RBS/EBS data to extract the depth profiles. The PIGE data can be supplied to the code in the usual way as counts versus beam energy, but the differential cross-sections for the PIGE reaction are required. We also compared the results obtained by the new routine with high resolution narrow resonance profiling (NRP) simulations obtained with the stochastic model of energy loss.

  10. The sensitivity of backscattering coefficients to elastic scattering cross-sections and electron stopping powers.

    Science.gov (United States)

    Walker, C G H; Matthew, J A D; El-Gomati, M M

    2014-01-01

    The sensitivity of Monte Carlo estimates of backscattering coefficients η to the accuracy of their input data is examined by studying the percentage change in η due to changes of 10% and 20% in the differential elastic scattering cross-section dσ/dΩ and corresponding changes in the stopping power S(E) in the primary energy range 200-10,000 eV. To a good approximation equivalent elastic and inelastic scattering changes produce equal and opposite shifts in η, a result consistent with predictions of transport theory. For medium to high atomic numbers an x% error in the specification of either S(E) or dσ/dΩ produces a percentage change in η significantly less than x%, while at low atomic number Δη/η increases approximately linearly with ln E so that Monte Carlo predictions are then more sensitive to parameter precision at high energy.

  11. Preliminary Thermal Characterization of a Fully-Passive Wireless Backscattering Neuro-Recording Microsystem

    Science.gov (United States)

    Schwerdt, H. N.; Xu, W.; Shekhar, S.; Chae, J.; Miranda, F. A.

    2011-01-01

    We present analytical and experimental thermal characteristics of a battery-less, fully-passive wireless backscattering microsystem for recording of neuropotentials. A major challenge for cortically implantable microsystems involves minimizing the heat dissipated by on-chip circuitry, which can lead to permanent brain damage. Therefore, knowledge of temperature changes induced by implantable microsystems while in operation is of utmost importance. In this work, a discrete diode appended to the neuro-recording microsystem has been used to indirectly monitor the aforesaid temperature changes. Using this technique, the maximum temperature rise measured for the microsystem while in operation was 0.15 +/- 0.1 C, which is significantly less than current safety guidelines. Specific absorption ratio (SAR) due to the microsystem was also computed to further demonstrate fully-passive functionality of the neuro-recording microsystem.

  12. Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish

    Directory of Open Access Journals (Sweden)

    Masahiko Furusawa

    2015-01-01

    Full Text Available Quantitative echosounders operating at multiple frequencies (e.g., 18, 38, 70, 120, 200, 333, and 710 kHz are often used to observe fish and zooplankton and identify their species. At frequencies above 100 kHz, the absorption attenuation increases rapidly and decreases the signal-to-noise ratio (SNR. Also, incomplete compensation for the attenuation may result in measurement error. This paper addresses the effects of the attenuation and noise on high frequency measurements of acoustic backscatter from fish. It is shown that measurements of a fish with target strength of −40 dB at 200 m depth are limited by SNR to frequencies up to about 100 kHz. Above 100 kHz, absorption coefficients must be matched to local environmental conditions.

  13. Transfer matrix analysis of backscattering and reflection effects on WDM-PON systems.

    Science.gov (United States)

    Simatupang, Joni Welman; Lee, San-Liang

    2013-11-18

    This paper proposes using power transfer matrix analysis to characterize the effects of Rayleigh backscattering and Fresnel reflection on WDM-PON systems. The modeling of a WDM-PON system can be carried out simply by matrix multiplication of the corresponding matrices for all the building blocks, where all possible guided backward lights and resonant configurations along the optical network can be accounted for. The total sum of all interferences affecting the bidirectional transmission that leads to an optical crosstalk-to-signal (C/S) ratio can be modeled as back-reflections through cascaded two-port networks for the downstream and upstream signals. This approach is simple, robust, efficient, and also accurate. Its accuracy is verified for simple system architectures and then applied to study more complicated cases. The results show its versatility to analyze a wide variety of bidirectional optical transmission systems.

  14. Impact of backscattered light in a squeezing-enhanced interferometric gravitational-wave detector

    CERN Document Server

    Chua, S S Y; Barsotti, L; Sigg, D; Schofield, R M S; Frolov, V V; Kawabe, K; Evans, M; Meadors, G D; Factourovich, M; Gustafson, R; Smith-Lefebvre, N; Vorvick, C; Landry, M; Khalaidovski, A; Stefszky, M S; Mow-Lowry, C M; Buchler, B C; Shaddock, D A; Lam, P K; Schnabel, R; Mavalvala, N; McClelland, D E

    2014-01-01

    Squeezed states of light have been recently used to improve the sensitivity of laser interferometric gravitational-wave detectors beyond the quantum limit. To completely establish quantum engineering as a realistic option for the next generation of detectors, it is crucial to study and quantify the noise coupling mechanisms which injection of squeezed states could potentially introduce. We present a direct measurement of the impact of backscattered light from a squeezed-light source deployed on one of the 4 km long detectors of the Laser Interferometric Gravitational Wave Observatory (LIGO). We also show how our measurements inform the design of squeezed light sources compatible with the even more sensitive advanced detectors currently under construction, such as Advanced LIGO.

  15. Probing Dynamics at Interfaces: Molecular Motions in Lipid Bilayers studied by Neutron Backscattering

    CERN Document Server

    Rheinstädter, M C; Salditt, T; Rheinst\\"adter, Maikel C.; Seydel, Tilo; Salditt, Tim

    2004-01-01

    Lipid membranes in a physiological context cannot be understood without taking into account their mobile environment. Here, we report on a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid supported phospholipid bilayers of the model system DMPC -d54 (deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine). This technique allows discriminating the Q-dependent onset of mobility and provides a benchmark test regarding the feasibility of dynamical neutron scattering investigations on these sample systems. Apart from freezing of the lipid acyl-chains, we could observe a second freezing temperature that we attribute to the hydration water in between the membrane stacks. The freezing is lowered several degrees as compared to (heavy) bulk water.

  16. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    Science.gov (United States)

    Wang, Xiaoqing; Chou, Kevin

    2016-11-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  17. Thomson backscattering diagnostics of nanosecond electron bunches in high space charge regime

    CERN Document Server

    Paroli, B

    2012-01-01

    The intra-beam repulsions play a significant role in determining the performances of free-electron devices when an high brilliance of the beam is required. The transversal and longitudinal spread of the beam, its energy and density are fundamental parameters in any beam experiment and different beam diagnostics are available to measure such parameters. A diagnostic method based on the Thomson backscattering of a laser beam impinging on the particle beam is proposed in this work for the study of nanosecond electron bunches in high space charge regime. This diagnostics, aimed to the measurement of density, energy and energy spread, was set-up in a Malmberg-Penning trap (generally used for the electron/ion confinment) in two different configurations designed to optimize sensitivity, spatial resolution and electron-beam coincidence in space and time. To this purpose an electron bunch (pulse time <4ns), produced by a photocathode source, was preliminary characterized with different electrostatic diagnostics and...

  18. Hydrogen release from sodium alanate observed by time-resolved neutron backscattering.

    Science.gov (United States)

    Léon, Aline; Wuttke, Joachim

    2011-06-29

    Innermolecular motion in Na(3)AlH(6) gives rise to a Lorentzian spectrum with a wavenumber-independent width of about 1  µeV at 180 °C, which is probably due to the rotation of AlH(6) tetrahedra. There is no such quasielastic line in NaAlH(4) or NaH. Based on this finding, time-resolved measurements on the neutron backscattering spectrometer SPHERES were used to monitor the decomposition kinetics of sodium alanate, [Formula: see text] NaH. Both reaction steps were found to be accelerated by autocatalysis, most likely at the surfaces of Na(3)AlH(6) and NaH crystallites.

  19. Hydrogen release from sodium alanate observed by time-resolved neutron backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Aline [Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Wuttke, Joachim, E-mail: aline.leon@kit.edu, E-mail: j.wuttke@fz-juelich.de [Juelich Centre for Neutron Science JCNS, Forschungszentrum Juelich GmbH, Outstation at FRM II, Lichtenbergstrasse 1, 85747 Garching (Germany)

    2011-06-29

    Innermolecular motion in Na{sub 3}AlH{sub 6} gives rise to a Lorentzian spectrum with a wavenumber-independent width of about 1 {mu}eV at 180 {sup 0}C, which is probably due to the rotation of AlH{sub 6} tetrahedra. There is no such quasielastic line in NaAlH{sub 4} or NaH. Based on this finding, time-resolved measurements on the neutron backscattering spectrometer SPHERES were used to monitor the decomposition kinetics of sodium alanate, NaAlH{sub 4{yields}}Na{sub 3}AlH{sub 6{yields}} NaH. Both reaction steps were found to be accelerated by autocatalysis, most likely at the surfaces of Na{sub 3}AlH{sub 6} and NaH crystallites.

  20. Analysis of Orange Peel Defect in St14 Steel Sheet by Electron Backscattered Diffraction (EBSD)

    Institute of Scientific and Technical Information of China (English)

    Shengquan CAO; Jinxu ZHANG; Jiansheng WU; Jiaguang CHEN

    2005-01-01

    In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110>orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.

  1. Validation of neutron data libraries by backscattered spectra of Pu-Be Neutrons

    CERN Document Server

    El-Agib, I

    1999-01-01

    Elastically backscattered spectra of Pu-Be neutrons have been measured for SiO sub 2 , water, graphite, paraffin oil and Al slabs using a proton recoil spectrometer. The results were compared with the calculated spectra obtained by the three-dimensional Monte-Carlo transport code MCNP-4B and point-wise cross sections from the ENDF/B-V, ENDF/B-VI, JENDL-3.1 and BROND-2 data libraries. The good agreement between the measured and calculated results indicates that this procedure can be used for validation of different data libraries. This simple method renders possible the detection of oxygen, carbon and hydrogen in bulk samples. (author)

  2. Radar altimetry backscattering signatures at Ka, Ku, C, and S bands over West Africa

    Science.gov (United States)

    Frappart, F.; Fatras, C.; Mougin, E.; Marieu, V.; Diepkilé, A. T.; Blarel, F.; Borderies, P.

    This study presents a comprehensive comparison of radar altimetry signatures at Ka-, Ku-, C-, and S-bands using SARAL, ENVISAT and Jason-2 data over the major bioclimatic zones, soil and vegetation types encountered in West-Africa, with an emphasis on the new information at Ka-band provided by the recently launched SARAL-Altika mission. Spatio-temporal variations of the radar altimetry responses were related to changes in surface roughness, land cover and soil wetness. Analysis of time series of backscattering coefficients along the West African bioclimatic gradient shows that radar echoes at nadir incidence are well correlated to soil moisture in semi-arid savannah environments. Radar altimeters are able to detect the presence of water even under a dense canopy cover at all frequencies. But only measurements at Ka-band are able to penetrate underneath the canopy of non-inundated tropical evergreen forests.

  3. Fluctuation spectra and velocity profile from Doppler backscattering on Tore Supra

    Science.gov (United States)

    Hennequin, P.; Honoré, C.; Truc, A.; Quéméneur, A.; Fenzi-Bonizec, C.; Bourdelle, C.; Garbet, X.; Hoang, G. T.; Tore Supra Team

    2006-09-01

    Backscattering of a microwave beam close to the cut-off allows for measurement of density fluctuations \\tilde n(\\vec k_\\perp) at a specified wave-number, selected by the scattering geometry \\vec k_\\perp=-2\\vec k_i , where ki is the beam wave-number at the reflection layer. On the Doppler reflectometry system installed on Tore Supra, both the scattering wave-number k⊥ and the scattering localization (r/a) can be changed during the shot owing to the steppable probing frequency and the motorized antenna. Operating in O mode, the spatial and wave-number ranges depend essentially on density profile, typically probing 0.5 electric field distribution. The dynamics of the fluctuation velocity can be studied from the time frequency analysis of the signal, for investigating intermittent behaviour and transient regimes.

  4. On the relationship of radar backscatter to wind speed and fetch. [ocean wave generation

    Science.gov (United States)

    Ross, D.; Jones, W. L.

    1978-01-01

    The physics of the interaction of electromagnetic waves with the ocean surface has been an active area of research for a number of years. This paper contains the results of satellite and aircraft experiments to investigate the ability of active microwave radars to infer surface wind speeds remotely. Data obtained from the recent National Aeronautics and Space Administration (NASA) Skylab experiment are compared with surface wind speeds measured by low-flying aircraft and ships-of-opportunity and found to give useful estimates of the ocean wind field. Also investigated was the influence of varying wave height on radar measurements of wind speed by measuring the backscattering cross-section for constant wind speed but variable wave conditions. It is found that this effect is of little importance.

  5. Enhanced backscattering for infrared detection using photonic crystal based flat lens.

    Science.gov (United States)

    Oden, Jonathan; Hofman, Maxence; Mélique, Xavier; Lippens, Didier; Vanbésien, Olivier

    2012-08-10

    An n=-1 flat lens based on photonic crystal semiconductor technology is evaluated for infrared detection purposes. The idea consists in exploiting the backscattered waves of an incident plane wave impinging on a target placed in the focal region of a flat lens. It is shown that subwavelength detection of micronic dielectric targets can be obtained at 1.55 μm using the double focus of reflected waves induced by negative refraction. Complex relations among the intrinsic nature, the shape and size of the target, and detection efficiency are interpreted in terms of target eigenmode excitation. Reflectivity is modulated by the intrinsic mode nature, transverse, circular, or longitudinal, with an enhancement of the detection sensitivity in the case of whispering-gallery modes. It is believed that such a study paves the way to the definition of original noninvasive infrared sensors.

  6. Use of mercuric iodide X-ray detectors with alpha backscattering spectrometers for space applications

    Science.gov (United States)

    Iwanczyk, J. S.; Wang, Y. J.; Dorri, N.; Dabrowski, A. J.; Economou, T. E.

    1991-01-01

    The authors present X-ray fluorescence (XRF) spectra of different extraterrestrial samples taken with a mercuric iodide (HgI2) spectrometer inserted into an alpha backscattering instrument identical to that used in the Soviet Phobos mission. The results obtained with the HgI2 ambient temperature detector are compared with those obtained using an Si(Li) cryogenically cooled detector. Efforts to design an optimized instrument for space application are also described. The results presented indicate that the energy resolution and sensitivity of HgI2 detectors are adequate to meet the performance needs of a number of proposed space applications, particularly those in which cooled silicon X-ray detectors are impractical or even not usable, such as for the target science programs on geoscience opportunities for lunar surface, Mars surface, and other comet and planetary missions being planned by NASA and ESA.

  7. The resolution of the tof-backscattering spectrometer OSIRIS: Monte Carlo simulations and analytical calculations

    Science.gov (United States)

    Demmel, F.; Pokhilchuk, K.

    2014-12-01

    The energy resolution of an indirect time of flight (tof) spectrometer is determined mainly by the pulse shape of the incoming pulse and the contribution of the crystal analyser. We performed extensive Monte Carlo simulations for the indirect near-backscattering spectrometer OSIRIS utilising the McStas neutron ray-traycing package. The simulations are accompanied by analytical calculations for the energy resolution. From simulation and calculation an excellent description for the width of the line is achieved for the PG002 and PG004 energy setting. The simulations and calculations reveal that the secondary spectrometer and hence the analyser geometry is the dominating term for the energy resolution at zero energy transfer. The remaining differences in the lineshape can be traced to a not perfectly modeled hydrogen moderator. The simulations and calculations predict a superb energy resolution of less than 100 μeV at an energy transfer of 15 meV.

  8. The resolution of the tof-backscattering spectrometer OSIRIS: Monte Carlo simulations and analytical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Demmel, F., E-mail: franz.demmel@stfc.ac.uk [ISIS Facility, Didcot, OX11 0QX (United Kingdom); Pokhilchuk, K. [ISIS Facility, Didcot, OX11 0QX (United Kingdom); Loughborough University, Loughborough (United Kingdom)

    2014-12-11

    The energy resolution of an indirect time of flight (tof) spectrometer is determined mainly by the pulse shape of the incoming pulse and the contribution of the crystal analyser. We performed extensive Monte Carlo simulations for the indirect near-backscattering spectrometer OSIRIS utilising the McStas neutron ray-traycing package. The simulations are accompanied by analytical calculations for the energy resolution. From simulation and calculation an excellent description for the width of the line is achieved for the PG002 and PG004 energy setting. The simulations and calculations reveal that the secondary spectrometer and hence the analyser geometry is the dominating term for the energy resolution at zero energy transfer. The remaining differences in the lineshape can be traced to a not perfectly modeled hydrogen moderator. The simulations and calculations predict a superb energy resolution of less than 100 μeV at an energy transfer of 15 meV.

  9. An atmospheric backscatter model on wind measurements using far-field approximation method

    Institute of Scientific and Technical Information of China (English)

    SHU Weiping; ZHAO Zhengyu

    2007-01-01

    A backscatter model was developed for measuring wind field with the far-field approximation method.The theoretical computation and computer simulations with one spatial dimension show that this model can realistically describe the physical meaning and process of the three methods in wind measurements including the spaced antenna (SA) method,Doppler beam swing (DBS) method,and spaced interferometry (SI).The computational difficulties of the traditional theoretical model cannot only be smoothed away,but common characteristics and differences of the three methods can be compared deeply.The comparison of the numerical results between the Wuhan medium frequency (MF) radar (30° N,114° E) observation and the computer simulation of the full correlation analysis (FCA) of the SA method indicates that the two results agree very well and this model has practical application.

  10. Distributed Temperature and Strain Discrimination with Stimulated Brillouin Scattering and Rayleigh Backscatter in an Optical Fiber

    Directory of Open Access Journals (Sweden)

    Xiaoyi Bao

    2013-01-01

    Full Text Available A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR. These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved.

  11. Imaging near-surface heterogeneities by natural migration of backscattered surface waves

    KAUST Repository

    AlTheyab, Abdullah

    2016-02-01

    We present a migration method that does not require a velocity model to migrate backscattered surface waves to their projected locations on the surface. This migration method, denoted as natural migration, uses recorded Green\\'s functions along the surface instead of simulated Green\\'s functions. The key assumptions are that the scattering bodies are within the depth interrogated by the surface waves, and the Green\\'s functions are recorded with dense receiver sampling along the free surface. This natural migration takes into account all orders of multiples, mode conversions and non-linear effects of surface waves in the data. The natural imaging formulae are derived for both active source and ambient-noise data, and computer simulations show that natural migration can effectively image near-surface heterogeneities with typical ambient-noise sources and geophone distributions.

  12. The sapphire backscattering monochromator at the Dynamics beamline P01 of PETRA III

    Science.gov (United States)

    Alexeev, P.; Asadchikov, V.; Bessas, D.; Butashin, A.; Deryabin, A.; Dill, F.-U.; Ehnes, A.; Herlitschke, M.; Hermann, R. P.; Jafari, A.; Prokhorov, I.; Roshchin, B.; Röhlsberger, R.; Schlage, K.; Sergueev, I.; Siemens, A.; Wille, H.-C.

    2016-12-01

    We report on a high resolution sapphire backscattering monochromator installed at the Dynamics beamline P01 of PETRA III. The device enables nuclear resonance scattering experiments on Mössbauer isotopes with transition energies between 20 and 60 keV with sub-meV to meV resolution. In a first performance test with 119Sn nuclear resonance at a X-ray energy of 23.88 keV an energy resolution of 1.34 meV was achieved. The device extends the field of nuclear resonance scattering at the PETRA III synchrotron light source to many further isotopes like 151Eu, 149Sm, 161Dy, 125Te and 121Sb.

  13. Adaptive characterization of recrystallization kinetics in IF steel by electron backscatter diffraction.

    Science.gov (United States)

    Kim, Dong-Kyu; Park, Won-Woong; Lee, Ho Won; Kang, Seong-Hoon; Im, Yong-Taek

    2013-12-01

    In this study, a rigorous methodology for quantifying recrystallization kinetics by electron backscatter diffraction is proposed in order to reduce errors associated with the operator's skill. An adaptive criterion to determine adjustable grain orientation spread depending on the recrystallization stage is proposed to better identify the recrystallized grains in the partially recrystallized microstructure. The proposed method was applied in characterizing the microstructure evolution during annealing of interstitial-free steel cold rolled to low and high true strain levels of 0.7 and 1.6, respectively. The recrystallization kinetics determined by the proposed method was found to be consistent with the standard method of Vickers microhardness. The application of the proposed method to the overall recrystallization stages showed that it can be used for the rigorous characterization of progressive microstructure evolution, especially for the severely deformed material.

  14. High-energy gamma-ray beams from Compton-backscattered laser light

    Energy Technology Data Exchange (ETDEWEB)

    Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G.; Matone, G.

    1983-01-01

    Collisions of light photons with relativistic electrons have previously been used to produce polarized ..gamma..-ray beams with modest (-10%) resolution but relatively low intensity. In contrast, the LEGS project (Laser + Electron Gamma Source) at Brookhaven will produce a very high flux (>2 x 10/sup 7/ s/sup -1/) of background-free polarized ..gamma.. rays whose energy will be determined to a high accuracy (..delta..E = 2.3 MeV). Initially, 300(420)-MeV ..gamma.. rays will be produced by backscattering uv light from the new 2.5(3.0)-GeV X-ray storage ring of the National Synchrotron Light Source (NSLS). The LEGS facility will operate as one of many passive users of the NSLS. In a later stage of the project, a Free Electron Laser is expectred to extend the ..gamma..-ray energy up to 700 MeV.

  15. Probing multifractality in depth-resolved refractive index fluctuations in biological tissues using backscattering spectral interferometry

    Science.gov (United States)

    Das, Nandan Kumar; Dey, Rajib; Chakraborty, Semanti; Panigrahi, P. K.; Ghosh, Nirmalya

    2016-12-01

    Fourier domain low coherence interferometry is a promising method for quantification of the depth distribution of the refractive index in a layered scattering medium such as biological tissue. Here, we have explored backscattering spectral interferometric measurement in combination with multifractal detrended fluctuation analysis to probe and quantify multifractality in depth distribution of the refractive index in tissue. The depth resolution of the experimental system was validated on model systems comprising of polystyrene microspheres and mica sheet, and was initially tested on turbid collagen layer, the main building blocks of the connective tissue. Following successful evaluation, the method was applied on ex vivo tissues of human cervix. The derived multifractal parameters of depth-resolved index fluctuations of tissue, namely, the generalized Hurst exponent and the width of the singularity spectrum showed interesting differences between tissues having different grades of precancers. The depth-resolved index fluctuations exhibited stronger multifractality with increasing pathological grades, demonstrating its promise as a potential biomarker for precancer detection.

  16. Multi-channel Doppler backscattering measurements in the C-2 field reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, L., E-mail: lschmitz@ucla.edu; Peebles, W. A. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States); Ruskov, E. [Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697 (United States); Deng, B. H.; Gota, H.; Gupta, D.; Tuszewski, M.; Douglass, J.; Binderbauer, M.; Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

    2014-11-15

    A versatile heterodyne Doppler Backscattering (DBS) system is used to measure density fluctuation levels (in the wavenumber range kρ{sub s} ≤ 50), and the toroidal E × B flow velocity in the C-2 Field-Reversed Configuration (FRC). Six tunable frequencies in three waveguide bands (26 GHz ≤ f ≤ 90 GHz) are launched using monostatic beam optics, via a quasi-optical beam combiner/polarizer and an adjustable parabolic focusing mirror (inside the vacuum enclosure) achieving Gaussian beam spot sizes of 3–5.5 cm at the X/O-mode cutoff. The DBS system covers plasma densities of 0.8 × 10{sup 13} ≤ n{sub e} ≤ 1 × 10{sup 14} cm{sup −3}, and provides access to the FRC core (up to the field null) and across the FRC separatrix into the scrape-off layer plasma.

  17. Experimental investigation of the dependence of radar backscattering on wind speed, wind stress and wave height

    Science.gov (United States)

    Gogineni, S. P.; Katsaros, K. B.

    1989-01-01

    During summer 1988, radar measurements were performed in conjunction with detailed environmental observations on Lake Washington at the University of Washington Sand Point field station. Radar data were collected at 5.3 and 10 GHz for incidence angles between 30 and 60 deg with VV-polarization. The environmental measurements included wind speed and direction, large-wave heights, the high-frequency portion of the wave spectrum, humidity, and air and water temperatures. The small-scale wave spectrum was measured using a resistance wire gauge. The results show that backscatter increased with wind speed as expected. However, little difference was observed in the scattering coefficient for upwind and crosswind directions. The results also indicated an increase in the amplitude of small waves with friction velocity.

  18. A Compact, Backscattering Deplolarization Cloud Spectrometer for Ice and Water Discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, David

    2014-05-15

    This project was to develop a compact optical particle spectrometer, small enough for operation on UAVS, that measures the optical diameter of cloud hydrometeors and differentiates their water phase (liquid or solid). To reach this goal, a work plan was laid out that would complete three objectives: 1) Evaluation of designs for an optical particle spectrometer that measures the component of light backscattered at two polarization angles. 2) Testing of selected designs on an optical bench. 3) Construction and preliminary testing of a prototype instrument based on the selected, optimum design. A protoype instrument was developed and tested in an icing wind tunnel where the results showed good measurement of cloud droplets and ice particles.

  19. On mathematical and physical principles of transformations of the coherent radar backscatter matrix

    CERN Document Server

    Bebbington, David

    2013-01-01

    The congruential rule advanced by Graves for polarization basis transformation of the radar backscatter matrix is now often misinterpreted as an example of consimilarity transformation. However, consimilarity transformations imply a physically unrealistic antilinear time-reversal operation. This is just one of the approaches found in literature to the description of transformations where the role of conjugation has been misunderstood. In this paper, the different approaches are examined in particular in respect to the role of conjugation. In order to justify and correctly derive the congruential rule for polarization basis transformation and properly place the role of conjugation, the origin of the problem is traced back to the derivation of the antenna hight from the transmitted field. In fact, careful consideration of the role played by the Green's dyadic operator relating the antenna height to the transmitted field shows that, under general unitary basis transformation, it is not justified to assume a scal...

  20. Large area stress distribution in crystalline materials calculated from lattice deformation identified by electron backscatter diffraction.

    Science.gov (United States)

    Shao, Yongliang; Zhang, Lei; Hao, Xiaopeng; Wu, Yongzhong; Dai, Yuanbin; Tian, Yuan; Huo, Qin

    2014-08-05

    We report a method to obtain the stress of crystalline materials directly from lattice deformation by Hooke's law. The lattice deformation was calculated using the crystallographic orientations obtained from electron backscatter diffraction (EBSD) technology. The stress distribution over a large area was obtained efficiently and accurately using this method. Wurtzite structure gallium nitride (GaN) crystal was used as the example of a hexagonal crystal system. With this method, the stress distribution of a GaN crystal was obtained. Raman spectroscopy was used to verify the stress distribution. The cause of the stress distribution found in the GaN crystal was discussed from theoretical analysis and EBSD data. Other properties related to lattice deformation, such as piezoelectricity, can also be analyzed by this novel approach based on EBSD data.