WorldWideScience

Sample records for polarimetric phase curves

  1. Novel Polarimetric SAR Interferometry Algorithms, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...

  2. Novel Polarimetric SAR Interferometry Algorithms, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  3. Interpulse phase coding for improving accuracy of polarimetric SAR

    Science.gov (United States)

    Giuli, Dino; Facheris, Luca

    1993-02-01

    Polarimetric measurements made by Synthetic Aperture Radar (SAR) may be in some cases, depending on the polarimetric response of distributed targets to be imaged, severely limited in their accuracy due to the joint effect of range ambiguities and weak crosspolarized signal response. Due to the utilization of alternate transmission of pulses at orthogonal polarizations, each ambiguous swath gives rise to one different kind of interference, depending whether its order is even or odd. Interference arising from even-order ambiguous swaths, differently from that arising from odd-order swaths, is generated by pulses transmitted on the same polarization channel of the pulse soliciting the desired echo signal, that they corrupt. Evidently, interference arising from odd-order swaths and affecting crosspolar measurements is most harmful, together with that arising from zones at low incidence angle, which carries a strong reflectivity contribution to the total interference on the desired signal. The paper discusses the utility of appropriate interpulse phase coding strategies, depending on the SAR geometry, than can be devised and utilized in the polarimetric interleaved-pulse measurement technique, with the task to reduce the interference generated by range ambiguities and affecting those target scattering matrix elements, whose measurement is expected to be most critical.

  4. The Design and Development of a Polarimetric Phased Array Airborne SAR Sensor

    NARCIS (Netherlands)

    Snoeij, P.; Pouwels, H.; Koomen, P.J.; Vermeulen, B.C.B.; Hoogeboom, P.

    1996-01-01

    A polarimetric C-band airborne SAR has been developed in the Netherlands. The system makes use of a phased array antenna with solid state amplifiers. The project consists of two phases, a definition phase and a realization phase. The definition phase consisted of the actual realization of a SAR

  5. Probing exoplanet clouds with optical phase curves.

    Science.gov (United States)

    Muñoz, Antonio García; Isaak, Kate G

    2015-11-03

    Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve--from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5.

  6. The CASLEO Polarimetric Survey of Main Belt Asteroids: Updated results

    Science.gov (United States)

    Gil-Hutton, R.; Cellino, A.; Cañada-Assandri, M.

    2011-10-01

    We present updated results of the polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina, using the 2.15 m telescope and the Torino and CASPROF polarimeters. The goals of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids belonging to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. The survey began in 2003, and data for a sample of more than 170 asteroids have been obtained, most of them having been polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for several taxonomic classes.

  7. Inferring cardiac phase response curve in vivo

    Science.gov (United States)

    Pikovsky, Arkady; Kralemann, Bjoern; Fruehwirth, Matthias; Rosenblum, Michael; Kenner, Thomas; Schaefer, Jochen; Moser, Maximilian

    2014-03-01

    Characterizing properties of biological oscillators with phase response cirves (PRC) is one of main theoretical tools in neuroscience, cardio-respiratory physiology, and chronobiology. We present a technique that allows the extraction of the PRC from a non-invasive observation of a system consisting of two interacting oscillators, in this case heartbeat and respiration, in its natural environment and under free-running conditions. We use this method to obtain the phase coupling functions describing cardio-respiratory interactions and the phase response curve of 17 healthy humans. We show at which phase the cardiac beat is susceptible to respiratory drive and extract the respiratory-related component of heart rate variability. This non-invasive method of bivariate data analysis for the determination of phase response curves of coupled oscillators may find application in other biological and physical systems.

  8. Spectro-polarimetric study of the early evolutionary phases of the most massive galaxies

    International Nuclear Information System (INIS)

    Vernet, Joel

    2001-01-01

    This research thesis addresses the study of the early phases of evolution of the most massive galaxies (giant elliptic), a fundamental process which is a matter of study for various reasons exposed by the author in his introduction. While presented results are based on spectro-polarimetric observations, the author first presents specific instruments and methods used by spectropolarimetry which provides access to variations of all vectorial properties of light, without loss of information. Then, he reports the study of a near powerful radio-galaxy, Cygnus A, the study of nine radio-galaxies with a high redshift, and the study of a far ultra-luminous infrared galaxy (SMM J02399-0136). Results are then discussed and perspectives of research are proposed. Appendices present the theoretical study of the contribution of massive stars to the diffuse extragalactic ionizing background, and observations made on a near radio-galaxy (NGC 6251)

  9. Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

    Directory of Open Access Journals (Sweden)

    R. A. Stillwell

    2018-02-01

    Full Text Available The unambiguous retrieval of cloud phase from polarimetric lidar observations is dependent on the assumption that only cloud scattering processes affect polarization measurements. A systematic bias of the traditional lidar depolarization ratio can occur due to a lidar system's inability to accurately measure the entire backscattered signal dynamic range, and these biases are not always identifiable in traditional polarimetric lidar systems. This results in a misidentification of liquid water in clouds as ice, which has broad implications on evaluating surface energy budgets. The Clouds Aerosol Polarization and Backscatter Lidar at Summit, Greenland employs multiple planes of linear polarization, and photon counting and analog detection schemes, to self evaluate, correct, and optimize signal combinations to improve cloud classification. Using novel measurements of diattenuation that are sensitive to both horizontally oriented ice crystals and counting system nonlinear effects, unambiguous measurements are possible by over constraining polarization measurements. This overdetermined capability for cloud-phase determination allows for system errors to be identified and quantified in terms of their impact on cloud properties. It is shown that lidar system dynamic range effects can cause errors in cloud-phase fractional occurrence estimates on the order of 30 % causing errors in attribution of cloud radiative effects on the order of 10–30 %. This paper presents a method to identify and remove lidar system effects from atmospheric polarization measurements and uses co-located sensors at Summit to evaluate this method. Enhanced measurements are achieved in this work with non-orthogonal polarization retrievals as well as analog and photon counting detection facilitating a more complete attribution of radiative effects linked to cloud properties.

  10. Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

    Science.gov (United States)

    Stillwell, Robert A.; Neely, Ryan R., III; Thayer, Jeffrey P.; Shupe, Matthew D.; Turner, David D.

    2018-02-01

    The unambiguous retrieval of cloud phase from polarimetric lidar observations is dependent on the assumption that only cloud scattering processes affect polarization measurements. A systematic bias of the traditional lidar depolarization ratio can occur due to a lidar system's inability to accurately measure the entire backscattered signal dynamic range, and these biases are not always identifiable in traditional polarimetric lidar systems. This results in a misidentification of liquid water in clouds as ice, which has broad implications on evaluating surface energy budgets. The Clouds Aerosol Polarization and Backscatter Lidar at Summit, Greenland employs multiple planes of linear polarization, and photon counting and analog detection schemes, to self evaluate, correct, and optimize signal combinations to improve cloud classification. Using novel measurements of diattenuation that are sensitive to both horizontally oriented ice crystals and counting system nonlinear effects, unambiguous measurements are possible by over constraining polarization measurements. This overdetermined capability for cloud-phase determination allows for system errors to be identified and quantified in terms of their impact on cloud properties. It is shown that lidar system dynamic range effects can cause errors in cloud-phase fractional occurrence estimates on the order of 30 % causing errors in attribution of cloud radiative effects on the order of 10-30 %. This paper presents a method to identify and remove lidar system effects from atmospheric polarization measurements and uses co-located sensors at Summit to evaluate this method. Enhanced measurements are achieved in this work with non-orthogonal polarization retrievals as well as analog and photon counting detection facilitating a more complete attribution of radiative effects linked to cloud properties.

  11. The Development of Polarimetric and Nonpolarimetric Multiwavelength Focal Plane Arrays, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance polarimetric and nonpolarimetric sensing is crucial to upcoming NASA missions, including ACE and CLARREO and the multi-agency VIIRS NPP project. The...

  12. Polarimetric Multiwavelength Focal Plane Arrays for ACE and CLARREO, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance polarimetric and nonpolarimetric sensing is crucial to upcoming NASA missions, including ACE and CLARREO and the multi-agency VIIRS NPP project. The...

  13. Analyzing Exoplanet Phase Curve Information Content: Toward Optimized Observing Strategies

    Science.gov (United States)

    Placek, Ben; Angerhausen, Daniel; Knuth, Kevin H.

    2017-10-01

    Secondary eclipses and phase curves reveal information about the reflectivity and heat distribution in exoplanet atmospheres. The phase curve is composed of a combination of reflected and thermally emitted light from the planet, and for circular orbits the phase curve peaks during the secondary eclipse or at an orbital phase of 0.5. Physical mechanisms have been discovered that shift the phase curve maximum of tidally locked close-in planets to the right, or left, of the secondary eclipse. These mechanisms include cloud formations and atmospheric superrotation, both of which serve to shift the thermally bright hot-spot or highly reflective bright spot of the atmosphere away from the sub-stellar point. Here, we present a methodology for optimizing observing strategies for both secondary eclipses and phase curves with the goal of maximizing the information gained about the planetary atmosphere while minimizing the (assumed) continuous observation time. We show that we can increase the duty cycle of observations aimed at the measurements of phase curve characteristics (amplitude, phase offset) by up to 50% for future platforms such as CHaracterising ExOPlanets Satellite (CHEOPS) and JWST. We apply this methodology to the test cases of the Spitzer phase curve of 55-Cancri-e, which displays an eastward shift in its phase curve maximum as well as model-generated observations of an ultra-short period planet observed with CHEOPS.

  14. High Order Mesh Curving and Geometry Access, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — During Phase I, our effort will focus on three software tools; CurveMesh, Geode and SLUGS. These tools will be developed in anticipation of use in the commercial...

  15. Phase Curve Analysis of Super-Earth 55 Cancri e

    Science.gov (United States)

    Angelo, Isabel; Hu, Renyu

    2018-01-01

    One of the primary questions when characterizing Earth-sized and super-Earth-sized exoplanets is whether they have a substantial atmosphere like Earth and Venus, or a bare-rock surface that may come with a tenuous atmosphere like Mercury. Phase curves of the planets in thermal emission provide clues to this question, because a substantial atmosphere would transport heat more efficiently than a bare-rock surface. Analyzing phase curve photometric data around secondary eclipse has previously been used to study energy transport in the atmospheres of hot Jupiters. Here we use phase curve, Spitzer time-series photometry to study the thermal emission properties of the super-Earth exoplanet 55 Cancri e. We utilize a previously developed semi-analytical framework to fit a physical model to infrared photometric data of host star 55 Cancri from the Spitzer telescope IRAC 2 band at 4.5 μm. The model uses various parameters of planetary properties including Bond albedo, heat redistribution efficiency (i.e., the ratio between the radiative timescale and advective timescale of the photosphere), and atmospheric greenhouse factor. The phase curve of 55 Cancri e is dominated by thermal emission with an eastward-shifted hot spot located on the planet surface. We determine the heat redistribution efficiency to be ≈1.47, which implies that the advective timescale is on the same order as the radiative timescale. This requirement from the phase curve cannot be met by the bare-rock planet scenario, because heat transport by currents of molten lava would be too slow. The phase curve thus favors the scenario with a substantial atmosphere. Our constraints on the heat redistribution efficiency translate to a photosphere pressure of ~1.4 bar. The Spitzer IRAC 2 band is thus a window into the deep atmosphere of the planet 55 Cancri e.

  16. On polarimetric radar signatures of deep convection for model evaluation: columns of specific differential phase observed during MC3E

    Energy Technology Data Exchange (ETDEWEB)

    van Lier-Walqui, Marcus; Fridlind, Ann; Ackerman, Andrew S; Collis, Scott; Helmus, Jonathan; MacGorman, Donald R; North, Kirk; Kollias, Pavlos; Posselt, Derek J

    2016-02-01

    The representation of deep convection in general circulation models is in part informed by cloud-resolving models (CRMs) that function at higher spatial and temporal resolution; however, recent studies have shown that CRMs often fail at capturing the details of deep convection updrafts. With the goal of providing constraint on CRM simulation of deep convection updrafts, ground-based remote sensing observations are analyzed and statistically correlated for four deep convection events observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). Since positive values of specific differential phase observed above the melting level are associated with deep convection updraft cells, so-called columns are analyzed using two scanning polarimetric radars in Oklahoma: the National Weather Service Vance WSR-88D (KVNX) and the Department of Energy C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar (C-SAPR). KVNX and C-SAPR volumes and columns are then statistically correlated with vertical winds retrieved via multi-Doppler wind analysis, lightning flash activity derived from the Oklahoma Lightning Mapping Array, and KVNX differential reflectivity . Results indicate strong correlations of volume above the melting level with updraft mass flux, lightning flash activity, and intense rainfall. Analysis of columns reveals signatures of changing updraft properties from one storm event to another as well as during event evolution. Comparison of to shows commonalities in information content of each, as well as potential problems with associated with observational artifacts.

  17. Light Curves and Low Phase Angle Photometry for Jupiter Trojans.

    Science.gov (United States)

    Chatelain, Joseph P.; Henry, Todd J.; Scott, Nicholas J.; French, Linda M.; Stephens, Robert D.

    2012-08-01

    We propose to make light curve observations in both the V and I filters as well as phase curve observations of the 26 brightest Jupiter Trojans, evenly selected from the L4 (Greek) and L5 (Trojan) Lagrangian camps. We are observing these objects as part of a comprehensive effort including 113 Greeks and Trojans using the CTIO 1.0m. With these light curve data we will update previously calculated variation amplitudes and look for color variations that can give details about shapes, orientations, surface features, and ages. None of these targets have published simultaneous color information. The phase information can provide insight into surface detail and composition. These data will also enable calibration of our ongoing photometry program that will reveal the possible origins of the two camps, which remain surprisingly obscure. Furthermore, the light curves are necessary to produce proper phase curves by allowing for the removal of any changes in brightness due to rotation. The proposed observations will comprise a significant portion of the PI's PhD thesis.

  18. SPIDERMAN: Fast code to simulate secondary transits and phase curves

    Science.gov (United States)

    Louden, Tom; Kreidberg, Laura

    2017-11-01

    SPIDERMAN calculates exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. The code uses a geometrical algorithm to solve exactly the area of sections of the disc of the planet that are occulted by the star. Approximately 1000 models can be generated per second in typical use, which makes making Markov Chain Monte Carlo analyses practicable. The code is modular and allows comparison of the effect of multiple different brightness distributions for a dataset.

  19. Studying ice particle growth processes in mixed-phase clouds using spectral polarimetric radar measurements

    NARCIS (Netherlands)

    Pfitzenmaier, L.

    2018-01-01

    Clouds are a prominent part of the Earth hydrological cycle. In the mid latitudes, the ice phase of clouds is highly involved in the formation of precipitation. The ice particles in the clouds fall to earth either as snow flakes, in the winter month, or melting crystals that become rain drops. An

  20. Ice crystal properties retrieval using radar spectral polarimetric measurements within ice/mixed-phase clouds

    NARCIS (Netherlands)

    Dufournet, Y.

    2010-01-01

    In the field of atmospheric research, ground-based radar systems are often employed to study ice/mixed-phase cloud properties based on retrieval techniques. These techniques convert the radar signal backscattered by each bulk of ice crystals being probed within the same radar resolution volume to

  1. Measured coexistence curves of phase-separated polymer solutions

    Science.gov (United States)

    Xia, K.-Q.; An, X.-Q.; Shen, W.-G.

    1996-10-01

    Measurements of the coexistence curves for phase-separated polymer solutions of polymethylmethacrylate in 3-octanone (PMMA/3-OCT) for six different molecular weights of PMMA have been carried out. We have tested the scaling behavior of the order parameter Δφ (the difference between polymer volume fractions in the two coexisting phases) for its dependence on the degree of polymerization N of the polymer chains and the reduced temperature ɛ=(Tc-T)/Tc. The experiments reveal that, in the asymptotic regime, the measured order parameter has power-law dependence on both N and ɛ, i.e., Δφ=3.8N-0.21ɛ0.34. Furthermore, when the symmerization procedure of Sanchez [J. Appl. Phys. 58, 2871 (1985)] is used to analyze the data, it suggests that ɛN0.46 may be used as a scaling variable for phase separated polymer solutions.

  2. Phase response curves for models of earthquake fault dynamics

    International Nuclear Information System (INIS)

    Franović, Igor; Kostić, Srdjan; Perc, Matjaž; Klinshov, Vladimir; Nekorkin, Vladimir; Kurths, Jürgen

    2016-01-01

    We systematically study effects of external perturbations on models describing earthquake fault dynamics. The latter are based on the framework of the Burridge-Knopoff spring-block system, including the cases of a simple mono-block fault, as well as the paradigmatic complex faults made up of two identical or distinct blocks. The blocks exhibit relaxation oscillations, which are representative for the stick-slip behavior typical for earthquake dynamics. Our analysis is carried out by determining the phase response curves of first and second order. For a mono-block fault, we consider the impact of a single and two successive pulse perturbations, further demonstrating how the profile of phase response curves depends on the fault parameters. For a homogeneous two-block fault, our focus is on the scenario where each of the blocks is influenced by a single pulse, whereas for heterogeneous faults, we analyze how the response of the system depends on whether the stimulus is applied to the block having a shorter or a longer oscillation period.

  3. Searching for Jet Emission in LMXBs: A Polarimetric View

    Directory of Open Access Journals (Sweden)

    Maria Cristina Baglio

    2017-10-01

    Full Text Available We present results taken from a study aiming at detecting the emission from relativistic particles jets in neutron star-low mass X-ray binaries using optical polarimetric observations. First, we focus on a polarimetric study performed on the persistent LMXB 4U 0614+091. Once corrected for interstellar effects, we measured an intrinsic linear polarization in the r-band of ~3% at a 3σ confidence level. This is in-line with the observation of an infrared excess in the spectral energy distribution (SED of the source, reported in a previous work, which the authors linked to the optically thin synchrotron emission of a jet. We then present a study performed on the transitional millisecond pulsar PSR J1023+0038 during quiescence. We measured a linear polarization of 1.09 ± 0.27% and 0.90 ± 0.17% in the V and R bands, respectively. The phase-resolved polarimetric curve of the source in the R-band reveals a hint of a sinusoidal modulation at the source orbital period. The NIR -optical SED of the system did not suggest the presence of a jet. We conclude that the optical linear polarization observed for PSR J1023+0038 is possibly due to Thomson scattering with electrons in the disc, as also suggested by the hint of the modulation of the R-band linear polarization at the system orbital period.

  4. On phases and length of curves in a cyclic quantum evolution

    International Nuclear Information System (INIS)

    Pati, A.K.

    1994-01-01

    The concept of a curve traced by a state vector in the Hilbert space is introduced into the general context of quantum evolutions and its length defined. Three important curves are identified and their relation to the dynamical phase, the geometric phase and the total phase are studied. These phases are reformulated in terms of the dynamical curve, the geometric curve and the natural curve. For any arbitrary cyclic evolution of a quantum system, it is shown that the dynamical phase, the geometric phase and their sums and/or differences can be expressed as the integral of the contracted length of some suitably-defined curves. With this, the phases of the quantum mechanical wave function attain new meaning. Also, new inequalities concerning the phases are presented. (author). 18 refs

  5. Macroscopic phase-resetting curves for spiking neural networks

    Science.gov (United States)

    Dumont, Grégory; Ermentrout, G. Bard; Gutkin, Boris

    2017-10-01

    The study of brain rhythms is an open-ended, and challenging, subject of interest in neuroscience. One of the best tools for the understanding of oscillations at the single neuron level is the phase-resetting curve (PRC). Synchronization in networks of neurons, effects of noise on the rhythms, effects of transient stimuli on the ongoing rhythmic activity, and many other features can be understood by the PRC. However, most macroscopic brain rhythms are generated by large populations of neurons, and so far it has been unclear how the PRC formulation can be extended to these more common rhythms. In this paper, we describe a framework to determine a macroscopic PRC (mPRC) for a network of spiking excitatory and inhibitory neurons that generate a macroscopic rhythm. We take advantage of a thermodynamic approach combined with a reduction method to simplify the network description to a small number of ordinary differential equations. From this simplified but exact reduction, we can compute the mPRC via the standard adjoint method. Our theoretical findings are illustrated with and supported by numerical simulations of the full spiking network. Notably our mPRC framework allows us to predict the difference between effects of transient inputs to the excitatory versus the inhibitory neurons in the network.

  6. Enantioseparation of α-Hydroxyallylphosphonates and Phosphonoallylic Carbonate Derivatives on Chiral Stationary Phases Using Sequential UV, Polarimetric, and Refractive Index Detection.

    Science.gov (United States)

    Hamper, Bruce C; Mannino, Michael P; Mueller, Melissa E; Harrison, Liam T; Spilling, Christopher D

    2016-09-01

    Chromatographic separation of the enantiomers of parent compounds dimethyl α-hydroxyallyl phosphonate and 1-(dimethoxyphosphoryl) allyl methyl carbonate was demonstrated by high-performance liquid chromatography (HPLC) using Chiralpak AS-H and ad-H chiral stationary phases (CSP), respectively, using a combination of UV, polarimetric, and refractive index detectors. A comparison was made of the separation efficiency and elution order of enantiomeric α-hydroxyallyl phosphonates and their carbonate derivatives on commercially available polysaccharide AS, ad, OD, IC-3, and Whelk-O 1 CSPs. In general, the α-hydroxyallyl phosphonates were resolved on the AS-H CSP, whereas the carbonate derivatives and were preferentially resolved on the ad-H CSP. The impact of aryl substitution on the resolution of analytes and was evaluated. Thermodynamic parameters determined for enantioselective adsorption hydroxyphosphonates and on the AS-H CSP and carbonate on the ad-H CSP demonstrated enthalpic control for separation of the enantiomers. Chirality 28:656-662, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Polarimetric survey of main-belt asteroids. I. Results for fifty seven S-, L-, and K-type objects

    Science.gov (United States)

    Gil-Hutton, R.; Cañada-Assandri, M.

    2011-05-01

    Aims: We present the first results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties, similar to those shown by the asteroid (234) Barbara. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15 m telescope. The Torino polarimeter is an instrument that allows the simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data on a sample of more than 170 asteroids were obtained. In this paper the results of 57 S-, L-, and K-type objects are presented, most of them are being polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for these taxonomic classes. Furthermore, we also find two candidates, (397) Vienna and (458) Hercynia, that could have a phase-polarization curve with a large inversion angle. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/A+A/529/A86

  8. Polarimetric microlensing of circumstellar discs

    Science.gov (United States)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  9. POLCAL - POLARIMETRIC RADAR CALIBRATION

    Science.gov (United States)

    Vanzyl, J.

    1994-01-01

    Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the

  10. NormaCurve: a SuperCurve-based method that simultaneously quantifies and normalizes reverse phase protein array data.

    Directory of Open Access Journals (Sweden)

    Sylvie Troncale

    Full Text Available MOTIVATION: Reverse phase protein array (RPPA is a powerful dot-blot technology that allows studying protein expression levels as well as post-translational modifications in a large number of samples simultaneously. Yet, correct interpretation of RPPA data has remained a major challenge for its broad-scale application and its translation into clinical research. Satisfying quantification tools are available to assess a relative protein expression level from a serial dilution curve. However, appropriate tools allowing the normalization of the data for external sources of variation are currently missing. RESULTS: Here we propose a new method, called NormaCurve, that allows simultaneous quantification and normalization of RPPA data. For this, we modified the quantification method SuperCurve in order to include normalization for (i background fluorescence, (ii variation in the total amount of spotted protein and (iii spatial bias on the arrays. Using a spike-in design with a purified protein, we test the capacity of different models to properly estimate normalized relative expression levels. The best performing model, NormaCurve, takes into account a negative control array without primary antibody, an array stained with a total protein stain and spatial covariates. We show that this normalization is reproducible and we discuss the number of serial dilutions and the number of replicates that are required to obtain robust data. We thus provide a ready-to-use method for reliable and reproducible normalization of RPPA data, which should facilitate the interpretation and the development of this promising technology. AVAILABILITY: The raw data, the scripts and the normacurve package are available at the following web site: http://microarrays.curie.fr.

  11. Development and Validation of a Polarimetric-MCScene 3D Atmospheric Radiation Model

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., Burlington, MA (United States); Hawes, Frederick [Spectral Sciences, Inc., Burlington, MA (United States); Fox, Marsha [Spectral Sciences, Inc., Burlington, MA (United States)

    2016-03-15

    Polarimetric measurements can substantially enhance the ability of both spectrally resolved and single band imagery to detect the proliferation of weapons of mass destruction, providing data for locating and identifying facilities, materials, and processes of undeclared and proliferant nuclear weapons programs worldwide. Unfortunately, models do not exist that efficiently and accurately predict spectral polarized signatures for the materials of interest embedded in complex 3D environments. Having such a model would enable one to test hypotheses and optimize both the enhancement of scene contrast and the signal processing for spectral signature extraction. The Phase I set the groundwork for development of fully validated polarimetric spectral signature and scene simulation models. This has been accomplished 1. by (a) identifying and downloading state-of-the-art surface and atmospheric polarimetric data sources, (b) implementing tools for generating custom polarimetric data, and (c) identifying and requesting US Government funded field measurement data for use in validation; 2. by formulating an approach for upgrading the radiometric spectral signature model MODTRAN to generate polarimetric intensities through (a) ingestion of the polarimetric data, (b) polarimetric vectorization of existing MODTRAN modules, and (c) integration of a newly developed algorithm for computing polarimetric multiple scattering contributions; 3. by generating an initial polarimetric model that demonstrates calculation of polarimetric solar and lunar single scatter intensities arising from the interaction of incoming irradiances with molecules and aerosols; 4. by developing a design and implementation plan to (a) automate polarimetric scene construction and (b) efficiently sample polarimetric scattering and reflection events, for use in a to be developed polarimetric version of the existing first-principles synthetic scene simulation model, MCScene; and 5. by planning a validation field

  12. Surface roughness of Saturn's rings and ring particles inferred from thermal phase curves

    Science.gov (United States)

    Morishima, Ryuji; Turner, Neal; Spilker, Linda

    2017-10-01

    We analyze thermal phase curves of all the main rings of Saturn (the A, B, C rings, and the Cassini division) measured by both the far-IR and mid-IR detectors of the Cassini Composite InfraRed Spectrometer (CIRS). All the rings show temperature increases toward zero phase angle, known as an opposition effect or thermal beaming. For the C ring and Cassini division, which have low optical depths, intra-particle shadowing is considered the dominant mechanism causing the effect. On the other hand, the phase curves of the optically thick B and A rings steepen significantly with decreasing absolute solar elevation angle from 21° to 14°, suggesting inter-particle shadowing plays an important role in these rings. We employ an analytic roughness model to estimate the degrees of surface roughness of the rings or ring particles. For optically thin rings, an isolated particle covered by spherical segment craters is employed while for the thick rings we approximate a packed particle layer as a slab covered by craters. The particles in the thin rings are found to have generally rough surfaces, except in the middle C ring. Across the C ring, the optical depth correlates with the degree of surface roughness. This may indicate that surface roughness comes mainly from particle clumping, while individual particles have rather smooth surfaces. For the optically thick rings, the surface roughness of the particle layer is found to be moderate. The modeled phase curves of optically thick rings are shallow if the phase angle change is primarily due to change of observer azimuthal angle. On the other hand, the phase curves are steep if the phase angle change is due to change of observer elevation angle, as inter-particle shadows become visible at higher observer elevation. In addition, the area of shadowed facets increases with decreasing solar elevation angle. These combined effects explain the large seasonal change of the phase curve steepness observed for the thick rings. The degrees

  13. On the feasibility of exomoon detection via exoplanet phase curve spectral contrast

    Science.gov (United States)

    Forgan, D. H.

    2017-09-01

    An exoplanet-exomoon system presents a superposition of phase curves to observers - the dominant component varies according to the planetary period, and the lesser component varies according to both the planetary and the lunar periods. If the spectra of the two bodies differ significantly, then it is likely that there are wavelength regimes where the contrast between the moon and planet is significantly larger. In principle, this effect could be used to isolate periodic oscillations in the combined phase curve. Being able to detect the exomoon component would allow a characterization of the exomoon radius, and potentially some crude atmospheric data. We run a parameter survey of combined exoplanet-exomoon phase curves, which shows that for most sets of planet-moon parameters, the lunar component of the phase curve is undetectable to current state-of-the-art transit observations. Even with future transit survey missions, measuring the exomoon signal will most likely require photometric precision of 10 parts per million or better. The only exception to this is if the moon is strongly tidally heated or in some way self-luminous. In this case, measurements of the phase curve at wavelengths greater than a few μm can be dominated by the lunar contribution. Instruments like the James Webb Space Telescope and its successors are needed to make this method feasible.

  14. Testing Atmospheric Circulation Theories with Multi-Wavelength Phase-Curve Observations of WASP-43b

    Science.gov (United States)

    Stevenson, Kevin B.; Bean, Jacob; Line, Michael R.; Fortney, Jonathan J.; Desert, Jean-Michel; Kreidberg, Laura; Showman, Adam P.; Kataria, Tiffany

    2016-01-01

    Interpretation of published Spitzer phase-curve observations suggest a temperature dependence in hot Jupiters' heat redistribution efficiencies. Planets with equilibrium temperatures below ~2000 K typically exhibit less-extreme day-night temperature contrasts, with the one exception being WASP-43b. The conclusion that WASP-43b has inefficient heat redistribution originates from our HST/WFC3 spectroscopic phase-curve measurements and may yet agree with the current view if there is a strong wavelength dependence. We will present new Spitzer phase-curve observations of WASP-43b at 3.6 and 4.5 microns that test this theory. Additionally, using the combined WASP-43b datasets, we will compare thermal and chemical abundance constraints from the day- and night-side emission spectra and discuss the implications of any inconsistencies.

  15. Polarimetric survey of main-belt asteroids. V. The unusual polarimetric behavior of V-type asteroids

    Science.gov (United States)

    Gil-Hutton, R.; López-Sisterna, C.; Calandra, M. F.

    2017-03-01

    Aims: We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the CASPROF and CASPOL polarimeters at the 2.15 m telescope. The CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation and CASPOL is a polarimeter based on a CCD detector, which allows us to observe fainter objects with better signal-to-noise ratio. Results: The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We obtained 55 polarimetric measurements for 28 V-type main belt asteroids, all of them polarimetrically observed for the first time. The data obtained in this survey let us find polarimetric parameters for (1459) Magnya and for a group of 11 small V-type objects with similar polarimetric behavior. These polarization curves are unusual since they show a shallow minimum and a small inversion angle in comparison with (4) Vesta, although they have a steeper slope at α0. This polarimetric behavior could be explained by differences in the regoliths of these asteroids. The observations of (2579) Spartacus, and perhaps also (3944) Halliday, indicate a inversion angle larger than 24-25°. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  16. Polarimetric survey of main-belt asteroids. II. Results for 58 B- and C-type objects

    Science.gov (United States)

    Gil-Hutton, R.; Cañada-Assandri, M.

    2012-03-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico el Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data on a sample of more than 170 asteroids were obtained. In this paper the results for 58 B- and C-type objects are presented, most of them polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for these taxonomic classes. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Tables 1 and 2 are available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A115

  17. Polarimetric neutron scattering

    International Nuclear Information System (INIS)

    Tasset, F.

    2001-01-01

    Polarimetric Neutron Scattering in introduced, both by, explaining methodological issues and the corresponding instrumental developments. After a short overview of neutron spin polarization and the neutron polarization 3d-vector a pictorial approach of the microscopic theory is used to show how a polarized beam interacts with lattice and magnetic Fourier components in a crystal. Examples are given of using Spherical Neutron Polarimetry (SNP) and the corresponding Cryopad polarimeter for the investigation of non-collinear magnetic structures. (R.P.)

  18. Polarimetric imagery collection experiment

    Science.gov (United States)

    Romano, Joao M.; Felton, Melvin; Chenault, David; Sohr, Brian

    2010-04-01

    The Spectral and Polarimetric Imagery Collection Experiment (SPICE) is a collaborative effort between the US Army ARDEC and ARL that is focused on the collection of mid-wave and long-wave infrared imagery using hyperspectral, polarimetric, and broadband sensors. The objective of the program is to collect a comprehensive database of the different modalities over the course of 1 to 2 years to capture sensor performance over a wide variety of weather conditions, diurnal, and seasonal changes inherent to Picatinny's northern New Jersey location. Using the Precision Armament Laboratory (PAL) tower at Picatinny Arsenal, the sensors will autonomously collect the desired data around the clock at different ranges where surrogate 2S3 Self-Propelled Howitzer targets are positioned at different viewing perspectives in an open field. The database will allow for: 1) Understanding of signature variability under adverse weather conditions; 2) Development of robust algorithms; 3) Development of new sensors; 4) Evaluation of polarimetric technology; and 5) Evaluation of fusing the different sensor modalities. In this paper, we will present the SPICE data collection objectives, the ongoing effort, the sensors that are currently deployed, and how this work will assist researches on the development and evaluation of sensors, algorithms, and fusion applications.

  19. One-phase and two-phase homologous curves for coolant pumps of the pressurized light water nuclear reactors

    International Nuclear Information System (INIS)

    Santos, G.A. dos.

    1990-01-01

    The two-phase coolant pump model of pressurized light water nuclear reactors is an important point for the loss of primary coolant accident analysis. The single-phase pump characteristics are an essential feature for operational transients studies, for example, the shut-down and start-up of pump. These parameters, in terms of the homologous curves, set up the complete performance of the pump and are input for transients and accidents analysis thermal-hydraulic codes. This work propose a mathematical model able to predict the single-phase and two-phase homologous curves where it was incorporated geometric and operational pump condition. The results were compared with the experimental tests data from literature and it has showed a good agreement. (author)

  20. The phase curve survey of the irregular saturnian satellites: A possible method of physical classification

    Science.gov (United States)

    Bauer, James M.; Grav, Tommy; Buratti, Bonnie J.; Hicks, Michael D.

    2006-09-01

    During its 2005 January opposition, the saturnian system could be viewed at an unusually low phase angle. We surveyed a subset of Saturn's irregular satellites to obtain their true opposition magnitudes, or nearly so, down to phase angle values of 0.01°. Combining our data taken at the Palomar 200-inch and Cerro Tololo Inter-American Observatory's 4-m Blanco telescope with those in the literature, we present the first phase curves for nearly half the irregular satellites originally reported by Gladman et al. [2001. Nature 412, 163-166], including Paaliaq (SXX), Siarnaq (SXXIX), Tarvos (SXXI), Ijiraq (SXXII), Albiorix (SXVI), and additionally Phoebe's narrowest angle brightness measured to date. We find centaur-like steepness in the phase curves or opposition surges in most cases with the notable exception of three, Albiorix and Tarvos, which are suspected to be of similar origin based on dynamical arguments, and Siarnaq.

  1. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  2. The Far-UV Wavelength Dependence of the Lunar Phase Curve as Seen by LRO LAMP

    Science.gov (United States)

    Liu, Y.; Retherford, K. D.; Greathouse, T. K.; Hendrix, A. R.; Cahill, J. T. S.; Mandt, K. E.; Gladstone, G. R.; Grava, C.; Egan, A. F.; Kaufmann, D. E.; Pryor, W. R.

    2017-10-01

    In this study we discuss the Far-UV wavelength dependence of the lunar phase curves for sample mare and highlands as seen by the LAMP instrument, and we report current derived Hapke parameters at Far-UV wavelengths for the study areas.

  3. The osmotic pressure of 3He-4He mixtures along the phase separation curve

    NARCIS (Netherlands)

    van de Klundert, L.J.M.; Bos, M.R.E.; van der Meij, J.A.M.; Steffens, H.A.

    1977-01-01

    The osmotic pressure of 3He-4He mixtures was measured along the phase separation curve at temperatures up to 500 mK by balancing it with the fountain pressure of pure 4He. The usefullness of the secondary osmotic pressure thermometer was reinvestigated.

  4. POLARIMETRIC OBSERVATIONS OF {sigma} ORIONIS E

    Energy Technology Data Exchange (ETDEWEB)

    Carciofi, A. C.; Faes, D. M. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Townsend, R. H. D. [Department of Astronomy, University of Wisconsin-Madison, Sterling Hall, 475 N. Charter Street, Madison, WI 53706 (United States); Bjorkman, J. E., E-mail: carciofi@usp.br [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States)

    2013-03-20

    Some massive stars possess strong magnetic fields that confine plasma in the circumstellar environment. These magnetospheres have been studied spectroscopically, photometrically, and, more recently, interferometrically. Here we report on the first firm detection of a magnetosphere in continuum linear polarization, as a result of monitoring {sigma} Ori E at the Pico dos Dias Observatory. The non-zero intrinsic polarization indicates an asymmetric structure whose minor elongation axis is oriented 150. Degree-Sign 0 east of the celestial north. A modulation of the polarization was observed with a period of half of the rotation period, which supports the theoretical prediction of the presence of two diametrally opposed, corotating blobs of gas. A phase lag of -0.085 was detected between the polarization minimum and the primary minimum of the light curve, suggestive of a complex shape of the plasma clouds. We present a preliminary analysis of the data with the Rigidly Rotating Magnetosphere model, which could not reproduce simultaneously the photometric and polarimetric data. A toy model comprising two spherical corotating blobs joined by a thin disk proved more successful in reproducing the polarization modulation. With this model we were able to determine that the total scattering mass of the thin disk is similar to the mass of the blobs (2M{sub b}/M{sub d} = 1.2) and that the blobs are rotating counterclockwise on the plane of the sky. This result shows that polarimetry can provide a diagnostic of the geometry of clouds, which will serve as an important constraint for improving the Rigidly Rotating Magnetosphere model.

  5. Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, N.; Rovinsky, J.; Maron, D.M. [Tel-Aviv Univ. (Israel)

    1995-09-01

    The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the `flow monograms` describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the `interface monograms`, whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system `operational monogram`. The `operational monogram` enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop.

  6. Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

    International Nuclear Information System (INIS)

    Brauner, N.; Rovinsky, J.; Maron, D.M.

    1995-01-01

    The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the 'flow monograms' describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the 'interface monograms', whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system 'operational monogram'. The 'operational monogram' enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop

  7. In-phase and anti-phase interference fringes in rocking curves of resonant X-ray dynamical diffraction

    International Nuclear Information System (INIS)

    Negishi, Riichirou; Fukamachi, Tomoe; Yoshizawa, Masami; Hirano, Kenji; Hirano, Keiichi; Kawamura, Takaaki

    2008-01-01

    We have observed the interference fringes that are in phase with each other in the diffracted and transmitted rocking curves of GaAs 200 reflection near the K-absorption edge of As. The fringes are in contrast with the well-known Pendelloesung fringes that are anti-phase with each other in the diffracted and transmitted waves. The origin of the in-phase interference fringe is analyzed to be due to the diffraction only by the imaginary part of the atomic scattering factor. It is also shown that the interference fringes become typical Pendelloesung fringes when the diffraction is caused only by the real part. (author)

  8. Interpretation of bent-crystal rocking curves using phase-space diagrams

    CERN Document Server

    Ren, B; Chapman, L D; Wu, X Y; Zhong, Z; Ivanov, I; Huang, X

    2000-01-01

    In developing a double bent-Laue crystal monochromator for synchrotron-based monochromatic computed tomography system, we applied a special projection of the phase-space diagram to interpret the shape of bent crystal rocking curves. Unlike the rigorous approach of the ray-tracing method, this graphical method provides direct pictures that allow checks of the physical significance of the shapes of the rocking curves, thereby providing quick guidelines for matching two bent crystals. The method's usefulness is demonstrated with our crexperimental results, and its limitations are discussed.

  9. Polarimetric Multispectral Imaging Technology

    Science.gov (United States)

    Cheng, L.-J.; Chao, T.-H.; Dowdy, M.; Mahoney, C.; Reyes, G.

    1993-01-01

    The Jet Propulsion Laboratory is developing a remote sensing technology on which a new generation of compact, lightweight, high-resolution, low-power, reliable, versatile, programmable scientific polarimetric multispectral imaging instruments can be built to meet the challenge of future planetary exploration missions. The instrument is based on the fast programmable acousto-optic tunable filter (AOTF) of tellurium dioxide (TeO2) that operates in the wavelength range of 0.4-5 microns. Basically, the AOTF multispectral imaging instrument measures incoming light intensity as a function of spatial coordinates, wavelength, and polarization. Its operation can be in either sequential, random access, or multiwavelength mode as required. This provides observation flexibility, allowing real-time alternation among desired observations, collecting needed data only, minimizing data transmission, and permitting implementation of new experiments. These will result in optimization of the mission performance with minimal resources. Recently we completed a polarimetric multispectral imaging prototype instrument and performed outdoor field experiments for evaluating application potentials of the technology. We also investigated potential improvements on AOTF performance to strengthen technology readiness for applications. This paper will give a status report on the technology and a prospect toward future planetary exploration.

  10. Modelling the phase curve and occultation of WASP-43b with SPIDERMAN

    Science.gov (United States)

    Louden, Tom

    2017-06-01

    Presenting SPIDERMAN, a fast code for calculating exoplanet phase curves and secondary eclipses with arbitrary two dimensional surface brightness distributions. SPIDERMAN uses an exact geometric algorithm to calculate the area of sub-regions of the planet that are occulted by the star, with no loss in numerical precision. The speed of this calculation makes it possible to run MCMCs to marginalise effectively over the underlying parameters controlling the brightness distribution of exoplanets. The code is fully open source and available over Github. We apply the code to the phase curve of WASP-43b using an analytical surface brightness distribution, and find an excellent fit to the data. We are able to place direct constraints on the physics of heat transport in the atmosphere, such as the ratio between advective and radiative timescales at different altitudes.

  11. Halftone information hiding technology based on phase feature of space filling curves

    Science.gov (United States)

    Hu, Jianhua; Cao, Peng; Dong, Zhihong; Cao, Xiaohe

    2017-08-01

    To solve the problems of the production of interference fringes (namely moiré in printing) and improve the image quality in printing process of halftone screening for information hiding, a halftone screening security technique based on the phase feature of space filling curves is studied in this paper. This method effectively solves the problem of moire and optimizes the quality of the screening, so that the images presented after screening have achieved good visual effect. The pseudo-random scrambling encryption of the plaintext information and the halftone screening technique based on the phase feature of the space filling curves are carried out when screening,which not only eliminates the common moire in the screening but also improves the image quality and the security of information.

  12. EFFECT OF LONGITUDE-DEPENDENT CLOUD COVERAGE ON EXOPLANET VISIBLE WAVELENGTH REFLECTED-LIGHT PHASE CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Matthew W.; Lewis, Nikole K.; Cahoy, Kerri [Department of Earth, Atmospheric, and Planetary Sciences. Massachusetts Institute of Technology (MIT) Cambridge, MA (United States); Marley, Mark [NASA Ames Research Center, Moffett Field, CA (United States); Morley, Caroline; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2015-05-10

    We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. Thermal and cloud properties for these exoplanets are derived using one-dimensional radiative-convective and cloud simulations. The presence of clouds on these exoplanets significantly alters their planetary albedo spectra. We confirm that non-uniform cloud coverage on the dayside of tidally locked exoplanets will manifest as changes to the magnitude and shift of the phase curve. In this work, we first investigate a test case of our model using a Jupiter-like planet, at temperatures consistent to 2.0 AU insolation from a solar type star, to consider the effect of H{sub 2}O clouds. We then extend our application of the model to the exoplanet Kepler-7b and consider the effect of varying cloud species, sedimentation efficiency, particle size, and cloud altitude. We show that, depending on the observational filter, the largest possible shift of the phase curve maximum will be ∼2°–10° for a Jupiter-like planet, and up to ∼30° (∼0.08 in fractional orbital phase) for hot-Jupiter exoplanets at visible wavelengths as a function of dayside cloud distribution with a uniformly averaged thermal profile. The models presented in this work can be adapted for a variety of planetary cases at visible wavelengths to include variations in planet–star separation, gravity, metallicity, and source-observer geometry. Finally, we tailor our model for comparison with, and confirmation of, the recent optical phase-curve observations of Kepler-7b with the Kepler space telescope. The average planetary albedo can vary between 0.1 and 0.6 for the 1300 cloud scenarios that were compared to the observations. Many of these cases cannot produce a high enough albedo to match the observations. We observe that smaller particle size and increasing cloud altitude have a strong effect on increasing albedo. In particular, we show that a set of models where Kepler-7b has roughly half of

  13. Making the Most of Kepler Photometry: Characterizing Exoplanets through Phase Curve Analysis

    Directory of Open Access Journals (Sweden)

    Esteves Lisa J.

    2015-01-01

    Full Text Available The Kepler mission’s long-term monitoring of stars through high-precision photometry has not only revealed a plethora of exoplanet transits but also provided valuable data for characterizing a subset of these planets. Using over four years of Kepler observations, we have derived phase curves for over a dozen planets, and use these measurements to constrain their mass, brightness/temperature and energy redistribution between the day and the night sides. In our new study, we also investigate possible offsets of the peak brightness of the phase curve, which could be indicative of inhomogeneous clouds and/or substantial winds in the planet’s atmosphere. We find significant offsets for over a half-dozen planets. With this growing sample of measured phase curves, we are able to better examine the trends of hot Jupiter energy budgets and albedos, and for the first time relate these properties to the presence of clouds or winds on a planet.

  14. Polarimetric survey of main-belt asteroids. VI. New results from the second epoch of the CASLEO survey

    Science.gov (United States)

    Gil-Hutton, R.; García-Migani, E.

    2017-11-01

    Aims: We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry and to estimate the diversity in the polarimetric properties of asteroids that belong to different taxonomic classes. Methods: The data were obtained using the CASPOL polarimeter at the 2.15 m telescope. CASPOL is a polarimeter based on a CCD detector and a Savart plate. The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. Results: We present and analyze the unpublished results for 128 asteroids of different taxonomic types, 55 of them observed for the first time. The observational data allowed us to find probable new cases of Barbarian objects but also two D-type objects, (565) Marbachia and (1481) Tubingia, that seem to have phase-polarization curves with a large inversion angle. The data obtained combined with data from the literature enabled us to find phase-polarization curves for 121 objects of different taxonomic types and to study the relations between several polarimetric and physical parameters. Using an approximation for the phase-polarization curve we found the index of refraction of the surface material and the scatter separation distance for all the objects with known polarimetric parameters. We also found that the inversion angle is a function of the index of refraction of the surface, while the phase angle where the minimum of polarization is produced provides information about the distance between scatter particles or, to some extent, the porosity of the surface. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la

  15. Radar Measurement of Human Polarimetric Micro-Doppler

    Directory of Open Access Journals (Sweden)

    David Tahmoush

    2013-01-01

    Full Text Available We use polarimetric micro-Doppler for the detection of arm motion, especially for the classification of whether someone has their arms swinging and is thus unloaded. The arm is often bent at the elbow, providing a surface somewhat similar to a dihedral. This is distinct from the more planar surfaces of the body which allows us to isolate the signals of the arm (and knee. The dihedral produces a double bounce that can be seen in polarimetric radar data by measuring the phase difference between HH and VV. This measurement can then be used to determine whether the subject is unloaded.

  16. Knowledge-based sea ice classification by polarimetric SAR

    DEFF Research Database (Denmark)

    Skriver, Henning; Dierking, Wolfgang

    2004-01-01

    Polarimetric SAR images acquired at C- and L-band over sea ice in the Greenland Sea, Baltic Sea, and Beaufort Sea have been analysed with respect to their potential for ice type classification. The polarimetric data were gathered by the Danish EMISAR and the US AIRSAR which both are airborne...... systems. A hierarchical classification scheme was chosen for sea ice because our knowledge about magnitudes, variations, and dependences of sea ice signatures can be directly considered. The optimal sequence of classification rules and the rules themselves depend on the ice conditions/regimes. The use...... of the polarimetric phase information improves the classification only in the case of thin ice types but is not necessary for thicker ice (above about 30 cm thickness)...

  17. Polarimetric survey of main-belt asteroids. IV. New results from the first epoch of the CASLEO survey

    Science.gov (United States)

    Gil-Hutton, R.; Cellino, A.; Bendjoya, Ph.

    2014-09-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 1995, and until 2012 data on a large sample of asteroids were obtained. We here present and analyze the unpublished results for 129 asteroids of different taxonomic types, 56 which were polarimetrically observed for the first time. We find that the asteroids (402) Chloe and (729) Watsonia are Barbarians, and asteroid (269) Justitia shows a phase - polarization curve that seems to have a small inversion angle. Data obtained in UBVRI colors allow us to sketch an analysis of the wavelength dependence of the degree of linear polarization for 31 asteroids, in spite of some large error bars in some cases. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A122

  18. Optical identity authentication scheme based on elliptic curve digital signature algorithm and phase retrieval algorithm.

    Science.gov (United States)

    Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2013-08-10

    An optical identity authentication scheme based on the elliptic curve digital signature algorithm (ECDSA) and phase retrieval algorithm (PRA) is proposed. In this scheme, a user's certification image and the quick response code of the user identity's keyed-hash message authentication code (HMAC) with added noise, serving as the amplitude and phase restriction, respectively, are digitally encoded into two phase keys using a PRA in the Fresnel domain. During the authentication process, when the two phase keys are presented to the system and illuminated by a plane wave of correct wavelength, an output image is generated in the output plane. By identifying whether there is a match between the amplitude of the output image and all the certification images pre-stored in the database, the system can thus accomplish a first-level verification. After the confirmation of first-level verification, the ECDSA signature is decoded from the phase part of the output image and verified to allege whether the user's identity is legal or not. Moreover, the introduction of HMAC makes it almost impossible to forge the signature and hence the phase keys thanks to the HMAC's irreversible property. Theoretical analysis and numerical simulations both validate the feasibility of our proposed scheme.

  19. Revisiting the Phase Curves of WASP-43b: Confronting Re-analyzed Spitzer Data with Cloudy Atmospheres

    DEFF Research Database (Denmark)

    Mendonça, João M.; Malik, Matej; Demory, Brice-Olivier

    2018-01-01

    and have a finite cloud-top pressure. The multi-wavelength phase curves are naturally consistent with our cloudy atmospheres, except for the 4.5 μm phase curve, which requires the presence of enhanced carbon dioxide in the atmosphere of WASP-43b. Multi-phase emission spectra at higher spectral resolution......Recently acquired Hubble and Spitzer phase curves of the short-period hot Jupiter WASP-43b make it an ideal target for confronting theory with data. On the observational front, we re-analyze the 3.6 and 4.5 μm Spitzer phase curves and demonstrate that our improved analysis better removes residual...

  20. Project PHARUS: Towards a polarimetric C-band airborne SAR

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Otten, M.P.G.; Pouwels, H.; Snoeij, P.

    1989-01-01

    A few years ago three institutes in the Netherlands developed a plan to design and build a polarimetric C-band aircraft SAR system of a novel design, called PHARUS (PHased Array Universal SAR), meant as a replacement for our current digital SLAR system. These institutes are the Physics and

  1. SPIDERMAN: an open-source code to model phase curves and secondary eclipses

    Science.gov (United States)

    Louden, Tom; Kreidberg, Laura

    2018-03-01

    We present SPIDERMAN (Secondary eclipse and Phase curve Integrator for 2D tempERature MAppiNg), a fast code for calculating exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. Using a geometrical algorithm, the code solves exactly the area of sections of the disc of the planet that are occulted by the star. The code is written in C with a user-friendly Python interface, and is optimised to run quickly, with no loss in numerical precision. Approximately 1000 models can be generated per second in typical use, making Markov Chain Monte Carlo analyses practicable. The modular nature of the code allows easy comparison of the effect of multiple different brightness distributions for the dataset. As a test case we apply the code to archival data on the phase curve of WASP-43b using a physically motivated analytical model for the two dimensional brightness map. The model provides a good fit to the data; however, it overpredicts the temperature of the nightside. We speculate that this could be due to the presence of clouds on the nightside of the planet, or additional reflected light from the dayside. When testing a simple cloud model we find that the best fitting model has a geometric albedo of 0.32 ± 0.02 and does not require a hot nightside. We also test for variation of the map parameters as a function of wavelength and find no statistically significant correlations. SPIDERMAN is available for download at https://github.com/tomlouden/spiderman.

  2. The Thermal Phase Curve Offset on Tidally and Nontidally Locked Exoplanets: A Shallow Water Model

    Energy Technology Data Exchange (ETDEWEB)

    Penn, James; Vallis, Geoffrey K, E-mail: jp492@exeter.ac.uk, E-mail: g.vallis@exeter.ac.uk [University of Exeter, Exeter, Devon (United Kingdom)

    2017-06-20

    Using a shallow water model with time-dependent forcing, we show that the peak of an exoplanet thermal phase curve is, in general, offset from the secondary eclipse when the planet is rotating. That is, the planetary hot spot is offset from the point of maximal heating (the substellar point) and may lead or lag the forcing; the extent and sign of the offset are functions of both the rotation rate and orbital period of the planet. We also find that the system reaches a steady state in the reference frame of the moving forcing. The model is an extension of the well-studied Matsuno–Gill model into a full spherical geometry and with a planetary-scale translating forcing representing the insolation received on an exoplanet from a host star. The speed of the gravity waves in the model is shown to be a key metric in evaluating the phase curve offset. If the velocity of the substellar point (relative to the planet’s surface) exceeds that of the gravity waves, then the hot spot will lag the substellar point, as might be expected by consideration of forced gravity wave dynamics. However, when the substellar point is moving slower than the internal wave speed of the system, the hottest point may lead the passage of the forcing. We provide an interpretation of this result by consideration of the Rossby and Kelvin wave dynamics, as well as, in the very slowly rotating case, a one-dimensional model that yields an analytic solution. Finally, we consider the inverse problem of constraining planetary rotation rate from an observed phase curve.

  3. GPM Ground Validation NOAA X-band Polarimetric Radar (NOXP) IPHEx V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NOAA X-band dual-Polarimetric radar (NOXP) IPHEx dataset consists of differential reflectivity, differential phase shift, co-polar cross...

  4. Bird Migration Echoes Observed by Polarimetric Radar

    OpenAIRE

    MINDA, Haruya; FURUZAWA, Fumie A.; SATOH, Shinsuke; NAKAMURA, Kenji

    2008-01-01

    A C-band polarimetric radar on Okinawa Island successfully observed large-scale bird migrations over the western Pacific Ocean. The birds generated interesting polarimetric signatures. This paper describes the signatures and speculates bird behavior.

  5. Dynamic Studies of Exoplanet Atmospheres: Revisiting the 3.6 micron Phase Curve of HD209458b

    Science.gov (United States)

    Lewis, Nikole; Knutson, Heather; Cowan, Nicolas; Zellem, Robert; Griffith, Caitlin; Fortney, Jonathan; Showman, Adam

    2013-10-01

    One of the best-characterized exoplanet atmospheres is that of HD209458b, which has been the target of numerous transit, eclipse, and phase-curve observations. Despite this wealth of observational information, the global circulation patterns in the atmosphere of this benchmark planet remain largely unconstrained. To date, only an upper limit on the amplitude of the phase variations of HD209458b at 8 microns has been reported. Recently, phase-curve observations of HD209458b at 3.6 and 4.5 microns were acquired with the hope of better understanding energy transport in this benchmark planetary atmosphere. Unfortunately, the 3.6 micron phase-curve observations have been found to be badly corrupted by an unidentified noise source and have subsequently been declared 'failed' by the SSC. Here we request to re-observe HD209458b's full-orbit phase-curve at 3.6 microns in order to combine it with the phase-curve information at 4.5 and 8 microns to give a clearer picture of the atmospheric processes shaping this planet's emitted flux as a function of pressure and longitude. A comparison of the HD209458b full-orbit phase-curve at 4.5 microns with predictions from global circulation models suggest that both the dayside thermal inversion and a possible lack of strong magnetic effects in the planet's atmosphere could be shaping its global circulation patterns. However, this picture is incomplete without the 3.6 micron phase curve, which probes fundamentally different pressure levels in HD209458b's atmosphere. Only with multi-wavelength phase-curve information can we begin to constrain the radiative, chemical, advective, and possibly magnetic processes shaping HD209458b's atmosphere.[The AORs for this observation are in program 60021.

  6. EXTRASOLAR STORMS: PRESSURE-DEPENDENT CHANGES IN LIGHT-CURVE PHASE IN BROWN DWARFS FROM SIMULTANEOUS HST AND SPITZER OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao; Apai, Dániel; Karalidi, Theodora [Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Marley, Mark S. [NASA Ames Research Center, Naval Air Station, Moffett Field, Mountain View, CA 94035 (United States); Flateau, Davin [Department of Planetary Sciences, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Showman, Adam P. [Department of Planetary Sciences, University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States); Metchev, Stanimir [The University of Western Ontario, Department of Physics and Astronomy, Centre for Planetary Science and Exploration, 1151 Richmond St., London, ON N6A 3K7 (Canada); Buenzli, Esther [Institute for Astronomy, ETH Zürich Wolfgang-Pauli-Str. 27, 8093 Zürich (Switzerland); Radigan, Jacqueline [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Artigau, Étienne [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada); Lowrance, Patrick J. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Burgasser, Adam J., E-mail: haoyang@email.arizona.edu, E-mail: apai@arizona.edu [Center for Astrophysics and Space Science, University of California, San Diego, La Jolla, CA 92093 (United States)

    2016-07-20

    We present Spitzer /Infrared Array Camera Ch1 and Ch2 monitoring of six brown dwarfs during eight different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous Hubble Space Telescope ( HST )/WFC3 G141 grism spectra during two epochs and derived light curves in five narrowband filters. Probing different pressure levels in the atmospheres, the multiwavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 to 13 hr. We compare the shapes of the light curves and estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. The phase differences between the two groups of light curves suggest that the modulations seen at lower and higher pressures may be introduced by different cloud layers.

  7. The Wavelength Dependence of the Lunar Phase Curve as Seen by the LRO LAMP

    Science.gov (United States)

    Liu, Y.; Retherford, K. D.; Greathouse, T. K.; Hendrix, A. R.; Mandt, K.; Gladstone, R.; Cahill, J. T.; Egan, A.; Kaufmann, D. E.; Grava, C.; Pryor, W. R.

    2016-12-01

    The Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) provides global coverage of both nightside and dayside of the Moon in the far ultraviolet (FUV) wavelengths. The nightside observations use roughly uniform diffuse illumination sources from interplanetary medium Lyman-α sky glow and UV-bright stars so that traditional photometric corrections do not apply. In contrast, the dayside observations use sunlight as its illumination source where bidirectional reflectance is measured. The bidirectional reflectance is dependent on the incident, emission, and phase angles as well as the soil properties. Thus the comparisons of dayside mapping and nightside mapping techniques offer a method for cross-comparing the photometric correction factors because the observations are made under different lighting and viewing conditions. Specifically, the nightside data well constrain the single-scattering coefficient. We'll discuss the wavelength dependence of the lunar phase curve as seen by the LAMP instrument in dayside data. Our preliminary results indicate that the reflectance in the FUV wavelengths decreases with the increasing phase angles from 0° to 90°, similar to the phase curve in the UV-visible wavelengths as studied by Hapke et al. (2012) using LRO wide angle camera (WAC) data, among other visible-wavelength lunar studies. Particularly, we'll report how coherent backscattering and shadow hiding contribute to the opposition surge, given the fact that the albedo at FUV wavelengths is extremely low and thus multiple scattering is significantly less important. Finally, we'll report the derived Hapke parameters at FUV wavelengths for our study areas.

  8. Phase Curves of Nix and Hydra from the New Horizons Imaging Cameras

    Science.gov (United States)

    Verbiscer, Anne J.; Porter, Simon B.; Buratti, Bonnie J.; Weaver, Harold A.; Spencer, John R.; Showalter, Mark R.; Buie, Marc W.; Hofgartner, Jason D.; Hicks, Michael D.; Ennico-Smith, Kimberly; Olkin, Catherine B.; Stern, S. Alan; Young, Leslie A.; Cheng, Andrew; (The New Horizons Team

    2018-01-01

    NASA’s New Horizons spacecraft’s voyage through the Pluto system centered on 2015 July 14 provided images of Pluto’s small satellites Nix and Hydra at viewing angles unattainable from Earth. Here, we present solar phase curves of the two largest of Pluto’s small moons, Nix and Hydra, observed by the New Horizons LOng Range Reconnaissance Imager and Multi-spectral Visible Imaging Camera, which reveal the scattering properties of their icy surfaces in visible light. Construction of these solar phase curves enables comparisons between the photometric properties of Pluto’s small moons and those of other icy satellites in the outer solar system. Nix and Hydra have higher visible albedos than those of other resonant Kuiper Belt objects and irregular satellites of the giant planets, but not as high as small satellites of Saturn interior to Titan. Both Nix and Hydra appear to scatter visible light preferentially in the forward direction, unlike most icy satellites in the outer solar system, which are typically backscattering.

  9. Characterizing dynamic interactions between ultradian glucocorticoid rhythmicity and acute stress using the phase response curve.

    Directory of Open Access Journals (Sweden)

    James Rankin

    Full Text Available The hypothalamic-pituitary-adrenal (HPA axis is a dynamic oscillatory hormone signalling system that regulates the pulsatile secretion of glucocorticoids from the adrenal glands. In addition to regulation of basal levels of glucocorticoids, the HPA axis provides a rapid hormonal response to stress that is vitally important for homeostasis. Recently it has become clear that glucocorticoid pulses encode an important biological signal that regulates receptor signalling both in the central nervous system and in peripheral tissues. It is therefore important to understand how stressful stimuli disrupt the pulsatile dynamics of this system. Using a computational model that incorporates the crucial feed-forward and feedback components of the axis, we provide novel insight into experimental observations that the size of the stress-induced hormonal response is critically dependent on the timing of the stress. Further, we employ the theory of Phase Response Curves to show that an acute stressor acts as a phase-resetting mechanism for the ultradian rhythm of glucocorticoid secretion. Using our model, we demonstrate that the magnitude of an acute stress is a critical factor in determining whether the system resets via a Type 1 or Type 0 mechanism. By fitting our model to our in vivo stress-response data, we show that the glucocorticoid response to an acute noise stress in rats is governed by a Type 0 phase-resetting curve. Our results provide additional evidence for the concept of a deterministic sub-hypothalamic oscillator regulating the ultradian glucocorticoid rhythm, which constitutes a highly responsive peripheral hormone system that interacts dynamically with hypothalamic inputs to regulate the overall hormonal response to stress.

  10. Revisiting the Phase Curves of WASP-43b: Confronting Re-analyzed Spitzer Data with Cloudy Atmospheres

    Science.gov (United States)

    Mendonça, João M.; Malik, Matej; Demory, Brice-Olivier; Heng, Kevin

    2018-04-01

    Recently acquired Hubble and Spitzer phase curves of the short-period hot Jupiter WASP-43b make it an ideal target for confronting theory with data. On the observational front, we re-analyze the 3.6 and 4.5 μm Spitzer phase curves and demonstrate that our improved analysis better removes residual red noise due to intra-pixel sensitivity, which leads to greater fluxes emanating from the nightside of WASP-43b, thus reducing the tension between theory and data. On the theoretical front, we construct cloud-free and cloudy atmospheres of WASP-43b using our Global Circulation Model (GCM), THOR, which solves the non-hydrostatic Euler equations (compared to GCMs that typically solve the hydrostatic primitive equations). The cloud-free atmosphere produces a reasonable fit to the dayside emission spectrum. The multi-phase emission spectra constrain the cloud deck to be confined to the nightside and have a finite cloud-top pressure. The multi-wavelength phase curves are naturally consistent with our cloudy atmospheres, except for the 4.5 μm phase curve, which requires the presence of enhanced carbon dioxide in the atmosphere of WASP-43b. Multi-phase emission spectra at higher spectral resolution, as may be obtained using the James Webb Space Telescope, and a reflected-light phase curve at visible wavelengths would further constrain the properties of clouds in WASP-43b.

  11. CLEAN Technique for Polarimetric ISAR

    Directory of Open Access Journals (Sweden)

    M. Martorella

    2008-01-01

    Full Text Available Inverse synthetic aperture radar (ISAR images are often used for classifying and recognising targets. To reduce the amount of data processed by the classifier, scattering centres are extracted from the ISAR image and used for classifying and recognising targets. This paper addresses the problem of estimating the position and the scattering vector of target scattering centres from polarimetric ISAR images. The proposed technique is obtained by extending the CLEAN technique, which was introduced in radar imaging for extracting scattering centres from single-polarisation ISAR images. The effectiveness of the proposed algorithm, namely, the Polarimetric CLEAN (Pol-CLEAN is tested on simulated and real data.

  12. Polarimetric optimization for clutter suppression in spectral polarimetric weather radar

    NARCIS (Netherlands)

    Yin, J.; Unal, C.M.H.; Russchenberg, H.W.J.

    2017-01-01

    For the polarimetric-Doppler weather radar, sometimes there are artifacts caused by radar system itself or external sources displaying in the radar plan position indicator (PPI). These artifacts are not confined to specific range bins and also they are non-stationary when observed in the Doppler

  13. Non-equilibrium phase stabilization versus bubble nucleation at a nanoscale-curved Interface

    Science.gov (United States)

    Schiffbauer, Jarrod; Luo, Tengfei

    Using continuum dynamic van der Waals theory in a radial 1D geometry with a Lennard-Jones fluid model, we investigate the nature of vapor bubble nucleation near a heated, nanoscale-curved convex interface. Vapor bubble nucleation and growth are observed for interfaces with sufficiently large radius of curvature while phase stabilization of a superheated fluid layer occurs at interfaces with smaller radius. The hypothesis that the high Laplace pressure required for stable equilibrium of very small bubbles is responsible for phase stability is tested by effectively varying the parameter which controls liquid-vapor surface tension. In doing so, the liquid-vapor surface tension- hence Laplace pressure-is shown to have limited effect on phase stabilization vs. bubble nucleation. However, the strong dependence of nucleation on leading-order momentum transport, i.e. viscous dissipation, near the heated inner surface is demonstrated. We gratefully acknowledge ND Energy for support through the ND Energy Postdoctoral Fellowship program and the Army Research Office, Grant No. W911NF-16-1-0267, managed by Dr. Chakrapani Venanasi.

  14. Phase transformation and cooling curves of the mild steel influenced by previous hot rolling

    Directory of Open Access Journals (Sweden)

    S. Rusz

    2016-10-01

    Full Text Available Rods from mild steel S235JR were intensively rolled in the laboratory continuous mill. Specifically defined temperature of phase transformation Ar was determined from the free cooling curves measured by the temperature scanner. The Ar value increased from 763 to 786 °C with rolling temperature descending from 1 200 to 800 °C. The value of Ar = 730 °C was obtained at free cooling of the non-deformed rod of the same diameter 9,8 mm from heating temperature 1 000 °C. The obtained results were compared with continuous cooling transformation (CCT and deformation continuous cooling transformation (DCCT diagrams based on the dilatometric tests.

  15. Learning curve in circular multipolar phased radiofrequency ablation of atrial fibrillation.

    Science.gov (United States)

    Martirosyan, Mihran; Kiss, Alexandra; Nagy-Baló, Edina; Sándorfi, Gábor; Tint, Diana; Édes, István; Csanádi, Zoltán

    2015-01-01

    Although atrial fibrillation (AF) ablation is considered a technically challenging procedure, studies on the learning curve of different pulmonary vein isolation (PVI) techniques are limited. We investigated the time-dependent changes in procedural parameters, complication rates, and in the 1-year clinical outcome during our initial experience with circular multipolar phased radiofrequency (RF) ablation. The first 132 consecutive patients (40 female; age: 56.6 ± 10.4 years) who underwent PVI with phased RF ablation for paroxysmal or persistent AF at our center were included in the study. Procedural parameters and atrial arrhythmia-free survival were compared in the first, second and third group of 44 successive patients. All pulmonary veins were successfully isolated in 44 (100%), 41 (93.8%) and 42 (95.5%) patients in Tierce 1, 2 and 3, respectively (p = 0.233). The number of RF applications (per vein) required for isolation and fluoroscopy times demonstrated a significant decrease with experience, and a trend towards lower procedure times in Tierces 2 and 3 was also observed. Atrial arrhythmia-free survival rates at 12 months postablation were 68.18%, 75%, and 70.75% in Tierce 1, Tierce 2 and Tierce 3, respectively (p = 0.772). Pericardial tamponade requiring percutaneous subxiphoid drainage occurred in 1 patient (Tierce 3) as the only significant procedural complication. A learning curve effect was demonstrated in fluoroscopy times and in the number of RF applications but not in the acute success and in the long-term arrhythmia-free survival with circular multipolar RF ablations.

  16. A Simplified Micromechanical Modeling Approach to Predict the Tensile Flow Curve Behavior of Dual-Phase Steels

    Science.gov (United States)

    Nanda, Tarun; Kumar, B. Ravi; Singh, Vishal

    2017-11-01

    Micromechanical modeling is used to predict material's tensile flow curve behavior based on microstructural characteristics. This research develops a simplified micromechanical modeling approach for predicting flow curve behavior of dual-phase steels. The existing literature reports on two broad approaches for determining tensile flow curve of these steels. The modeling approach developed in this work attempts to overcome specific limitations of the existing two approaches. This approach combines dislocation-based strain-hardening method with rule of mixtures. In the first step of modeling, `dislocation-based strain-hardening method' was employed to predict tensile behavior of individual phases of ferrite and martensite. In the second step, the individual flow curves were combined using `rule of mixtures,' to obtain the composite dual-phase flow behavior. To check accuracy of proposed model, four distinct dual-phase microstructures comprising of different ferrite grain size, martensite fraction, and carbon content in martensite were processed by annealing experiments. The true stress-strain curves for various microstructures were predicted with the newly developed micromechanical model. The results of micromechanical model matched closely with those of actual tensile tests. Thus, this micromechanical modeling approach can be used to predict and optimize the tensile flow behavior of dual-phase steels.

  17. Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

  18. Grating-based x-ray differential phase contrast imaging with twin peaks in phase-stepping curves-phase retrieval and dewrapping.

    Science.gov (United States)

    Yang, Yi; Xie, Huiqiao; Cai, Weixing; Mao, Hui; Tang, Xiangyang

    2016-06-01

    X-ray differential phase contrast CT implemented with Talbot interferometry employs phase-stepping to extract information of x-ray attenuation, phase shift, and small-angle scattering. Since inaccuracy may exist in the absorption grating G2 due to an imperfect fabrication, the effective period of G2 can be as large as twice the nominal period, leading to a phenomenon of twin peaks that differ remarkably in their heights. In this work, the authors investigate how to retrieve and dewrap the phase signal from the phase-stepping curve (PSC) with the feature of twin peaks for x-ray phase contrast imaging. Based on the paraxial Fresnel-Kirchhoff theory, the analytical formulae to characterize the phenomenon of twin peaks in the PSC are derived. Then an approach to dewrap the retrieved phase signal by jointly using the phases of the first- and second-order Fourier components is proposed. Through an experimental investigation using a prototype x-ray phase contrast imaging system implemented with Talbot interferometry, the authors evaluate and verify the derived analytic formulae and the proposed approach for phase retrieval and dewrapping. According to theoretical analysis, the twin-peak phenomenon in PSC is a consequence of combined effects, including the inaccuracy in absorption grating G2, mismatch between phase grating and x-ray source spectrum, and finite size of x-ray tube's focal spot. The proposed approach is experimentally evaluated by scanning a phantom consisting of organic materials and a lab mouse. The preliminary data show that compared to scanning G2 over only one single nominal period and correcting the measured phase signal with an intuitive phase dewrapping method that is being used in the field, stepping G2 over twice its nominal period and dewrapping the measured phase signal with the proposed approach can significantly improve the quality of x-ray differential phase contrast imaging in both radiograph and CT. Using the phase retrieval and dewrapping

  19. Human phase response curve to intermittent blue light using a commercially available device

    Science.gov (United States)

    Revell, Victoria L; Molina, Thomas A; Eastman, Charmane I

    2012-01-01

    Light shifts the timing of the circadian clock according to a phase response curve (PRC). To date, all human light PRCs have been to long durations of bright white light. However, melanopsin, the primary photopigment for the circadian system, is most sensitive to short wavelength blue light. Therefore, to optimise light treatment it is important to generate a blue light PRC. We used a small, commercially available blue LED light box, screen size 11.2 × 6.6 cm at ∼50 cm, ∼200 μW cm−2, ∼185 lux. Subjects participated in two 5 day laboratory sessions 1 week apart. Each session consisted of circadian phase assessments to obtain melatonin profiles before and after 3 days of free-running through an ultradian light–dark cycle (2.5 h wake in dim light, 1.5 h sleep in the dark), forced desynchrony protocol. During one session subjects received intermittent blue light (three 30 min pulses over 2 h) once a day for the 3 days of free-running, and in the other session (control) they remained in dim room light, counterbalanced. The time of blue light was varied among subjects to cover the entire 24 h day. For each individual, the phase shift to blue light was corrected for the free-run determined during the control session. The blue light PRC had a broad advance region starting in the morning and extending through the afternoon. The delay region started a few hours before bedtime and extended through the night. This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world. PMID:22753544

  20. Estimation of error on the cross-correlation, phase and time lag between evenly sampled light curves

    Science.gov (United States)

    Misra, R.; Bora, A.; Dewangan, G.

    2018-04-01

    Temporal analysis of radiation from Astrophysical sources like Active Galactic Nuclei, X-ray Binaries and Gamma-ray bursts provides information on the geometry and sizes of the emitting regions. Establishing that two light-curves in different energy bands are correlated, and measuring the phase and time-lag between them is an important and frequently used temporal diagnostic. Generally the estimates are done by dividing the light-curves into large number of adjacent intervals to find the variance or by using numerically expensive simulations. In this work we have presented alternative expressions for estimate of the errors on the cross-correlation, phase and time-lag between two shorter light-curves when they cannot be divided into segments. Thus the estimates presented here allow for analysis of light-curves with relatively small number of points, as well as to obtain information on the longest time-scales available. The expressions have been tested using 200 light curves simulated from both white and 1 / f stochastic processes with measurement errors. We also present an application to the XMM-Newton light-curves of the Active Galactic Nucleus, Akn 564. The example shows that the estimates presented here allow for analysis of light-curves with relatively small (∼ 1000) number of points.

  1. Discrimination of Closely-Spaced Geosynchronous Satellites - Phase Curve Analysis & New Small Business Innovative Research (SBIR) Efforts

    Science.gov (United States)

    Levan, P.

    2010-09-01

    Geosynchronous objects appear as unresolved blurs even when observed with the largest ground-based telescopes. Due to the lack of any spatial detail, two or more objects appearing at similar brightness levels within the spectral bandpass they are observed are difficult to distinguish. Observing a changing pattern of such objects from one time epoch to another showcases the deficiencies in associating individual objects before and after the configuration change. This paper explores solutions to this deficiency in the form of spectral (under small business innovative research) and phase curve analyses. The extension of the technique to phase curves proves to be a powerful new capability.

  2. An Icon-Based Synoptic Visualization of Fully Polarimetric Radar Data

    Directory of Open Access Journals (Sweden)

    Iain H. Woodhouse

    2012-03-01

    Full Text Available The visualization of fully polarimetric radar data is hindered by traditional remote sensing methodologies for displaying data due to the large number of parameters per pixel in such data, and the non-scalar nature of variables such as phase difference. In this paper, a new method is described that uses icons instead of image pixels to represent the image data so that polarimetric properties and geographic context can be visualized together. The icons are parameterized using the alpha-entropy decomposition of polarimetric data. The resulting image allows the following five variables to be displayed simultaneously: unpolarized power, alpha angle, polarimetric entropy, anisotropy and orientation angle. Examples are given for both airborne and laboratory-based imaging.

  3. Phonon dispersion curves determination in (delta)-phase Pu-Ga alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wong, J; Clatterbuck, D; Occelli, F; Farber, D; Schwartz, A; Wall, M; Boro, C; Krisch, M; Beraud, A; Chiang, T; Xu, R; Hong, H; Zschack, P; Tamura, N

    2006-02-07

    We have designed and successfully employed a novel microbeam on large grain sample concept to conduct high resolution inelastic x-ray scattering (HRIXS) experiments to map the full phonon dispersion curves of an fcc {delta}-phase Pu-Ga alloy. This approach obviates experimental difficulties with conventional inelastic neutron scattering due to the high absorption cross section of the common {sup 239}Pu isotope and the non-availability of large (mm size) single crystal materials for Pu and its alloys. A classical Born von-Karman force constant model was used to model the experimental results, and no less than 4th nearest neighbor interactions had to be included to account for the observation. Several unusual features including, a large elastic anisotropy, a small shear elastic modulus, (C{sub 11}-C{sub 12})/2, a Kohn-like anomaly in the T{sub 1}[011] branch, and a pronounced softening of the T[111] branch towards the L point in the Brillouin are found. These features may be related to the phase transitions of plutonium and to strong coupling between the crystal structure and the 5f valence instabilities. Our results represent the first full phonon dispersions ever obtained for any Pu-bearing material, thus ending a 40-year quest for this fundamental data. The phonon data also provide a critical test for theoretical treatments of highly correlated 5f electron systems as exemplified by recent dynamical mean field theory (DMFT) calculations for {delta}-plutonium. We also conducted thermal diffuse scattering experiments to study the T(111) dispersion at low temperatures with an attempt to gain insight into bending of the T(111) branch in relationship to the {delta} {yields} {alpha}{prime} transformation.

  4. Polarimetric Coherence Optimization for Multibaseline SAR Data

    Science.gov (United States)

    Neumann, M.; Ferro-Famil, L.; Reigber, A.

    2007-03-01

    This paper analyzes different approaches for polarimetric optimization of multibaseline interferometric coherences. Two general methods are developed which simultaneously optimize coherences for more than two datasets. The first method is based on multiset canonical correlation analysis, and it provides every dataset with a distinguished dominant scattering mechanism. The second optimization method is constrained to the use of an identical scattering mechanism for every dataset. A framework for a multibaseline orthogonal optimal scattering mechanisms decomposition is presented. The both methods are evaluated on real data acquired by DLR's ESAR sensor at L-band. As experimental results indicate, preferring simultaneous multibaseline coherence optimization to single-baseline optimization improves the estimation of the dominant scattering mechanisms and their interferometric phases.

  5. Polarimetric Segmentation Using Wishart Test Statistic

    DEFF Research Database (Denmark)

    Skriver, Henning; Schou, Jesper; Nielsen, Allan Aasbjerg

    2002-01-01

    ) approach, which is a merging algorithm for single channel SAR images. The polarimetric version described in this paper uses the above-mentioned test statistic for merging. The segmentation algorithm has been applied to polarimetric SAR data from the Danish dual-frequency, airborne polarimetric SAR, EMISAR......A newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic has been used in a segmentation algorithm. The segmentation algorithm is based on the MUM (merge using moments....... The results show clearly an improved segmentation performance for the full polarimetric algorithm compared to single channel approaches....

  6. ASTEROID POLARIMETRIC DATABASE V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  7. ASTEROID POLARIMETRIC DATABASE V4.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  8. ASTEROID POLARIMETRIC DATABASE V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  9. ASTEROID POLARIMETRIC DATABASE V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  10. New polarimetric and spectroscopic evidence of anomalous enrichment in spinel-bearing calcium-aluminium-rich inclusions among L-type asteroids

    Science.gov (United States)

    Devogèle, M.; Tanga, P.; Cellino, A.; Bendjoya, Ph.; Rivet, J.-P.; Surdej, J.; Vernet, D.; Sunshine, J. M.; Bus, S. J.; Abe, L.; Bagnulo, S.; Borisov, G.; Campins, H.; Carry, B.; Licandro, J.; McLean, W.; Pinilla-Alonso, N.

    2018-04-01

    Asteroids can be classified into several groups based on their spectral reflectance. Among these groups, the one belonging to the L-class in the taxonomic classification based on visible and near-infrared spectra exhibit several peculiar properties. First, their near-infrared spectrum is characterized by a strong absorption band interpreted as the diagnostic of a high content of the FeO bearing spinel mineral. This mineral is one of the main constituents of Calcium-Aluminum-rich Inclusions (CAI) the oldest mineral compounds found in the solar system. In polarimetry, they possess an uncommonly large value of the inversion angle incompatible with all known asteroid belonging to other taxonomical classes. Asteroids found to possess such a high inversion angle are commonly called Barbarians based on the first asteroid on which this property was first identified, (234) Barbara. In this paper we present the results of an extensive campaign of polarimetric and spectroscopic observations of L-class objects. We have derived phase-polarization curves for a sample of 7 Barbarians, finding a variety of inversion angles ranging between 25 and 30°. Spectral reflectance data exhibit variations in terms of spectral slope and absorption features in the near-infrared. We analyzed these data using a Hapke model to obtain some inferences about the relative abundance of CAI and other mineral compounds. By combining spectroscopic and polarimetric results, we find evidence that the polarimetric inversion angle is directly correlated with the presence of CAI, and the peculiar polarimetric properties of Barbarians are primarily a consequence of their anomalous composition.

  11. Science Drivers for Polarimetric Exploration

    Science.gov (United States)

    Yanamandra-Fisher, Padma

    2017-04-01

    The versatility of polarimetric exploration is exploited to address: (1) understanding the formation of planetary systems and their diversity; and (2) search for habitability. Polarized light occurs in three states: unpolarized, linear and circularized. Each mode of polarized light provides information about the scattering medium, from atmospheres to search for signatures of habitability. Spectral dependence of polarization is important to separate the macroscopic (bulk) properties of the scattering medium from the microscopic (particulate) properties of the scattering medium. Linear polarization of reflected light by solar system objects provides insight into the scattering characteristics of aerosols and hazes in atmospheres and surficial properties of atmosphereless objects, circular polarization and related chirality (or handedness, a property of molecules that exhibit mirror-image symmetry, similar to right and left hands) can serve as diagnostic of biological activity. Atmospheric phenomena such as rainbows, clouds and haloes exhibit polarimetric signatures that can be used as diagnostics to probe the atmosphere and may be possible to extend this approach to other planets and exoplanets. Biological molecules exhibit an inherent handedness or circular polarization or chirality, assisting in search for the identification of astrobiological material in the solar system. Polarimetry is also utilized in the exploration of comets, asteroids, dust/regoliths. Renewed efforts for ground-based polarimetry are emerging, from probing planetary atmospheres to the study of magnetic field lines and taxonomy of asteroids. While imaging and spectroscopy are routinely performed by amateurs, there is growing interest and progress in developing polarimetric exploration amongst the amateur community, with encouraging results.I will present a review of these efforts and the goal to create a global " PACA* Polarimetry Network" of observers, modelers and instrument experts to fully

  12. Effect of Phase Response Curve Skew on Synchronization with and without Conduction Delays

    Directory of Open Access Journals (Sweden)

    Carmen eCanavier

    2013-12-01

    Full Text Available A central problem in cortical processing including sensory binding and attentional gating is how neurons can synchronize their responses with zero or near-zero time lag. For a spontaneously firing neuron, an input from another neuron can delay or advance the next spike by different amounts depending upon the timing of the input relative to the previous spike. This information constitutes the phase response curve (PRC. We present a simple graphical method for determining the effect of PRC shape on synchronization tendencies and illustrate it using type 1 PRCs, which consist entirely of advances (delays in response to excitation (inhibition. We obtained the following generic solutions for type 1 PRCs, which include the pulse coupled leaky integrate and fire model. For pairs with mutual excitation, exact synchrony can be stable for strong coupling because of the stabilizing effect of the causal limit region of the PRC in which an input triggers a spike immediately upon arrival. However, synchrony is unstable for short delays, because delayed inputs arrive during a refractory period and cannot trigger an immediate spike. Right skew destabilizes antiphase and enables modes with time lags that grow as the conduction delay is increased. Therefore, right skew favors near-synchrony at short conduction delays and a gradual transition between synchrony and antiphase for pairs coupled by mutual excitation. For pairs with mutual inhibition, zero time lag synchrony is stable for conduction delays ranging from zero to a substantial fraction of the period for pairs. However, for right skew there is a preferred antiphase mode at short delays. In contrast to mutual excitation, left skew destabilizes antiphase for mutual inhibition so that synchrony dominates at short delays as well. These pairwise synchronization tendencies constrain the synchronization properties of neurons embedded in larger networks.

  13. HIGH-RESOLUTION LINEAR POLARIMETRIC IMAGING FOR THE EVENT HORIZON TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Chael, Andrew A.; Johnson, Michael D.; Narayan, Ramesh; Doeleman, Sheperd S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wardle, John F. C. [Brandeis University, Physics Department, Waltham, MA 02454 (United States); Bouman, Katherine L., E-mail: achael@cfa.harvard.edu [Massachusetts Institute of Technology, Computer Science and Artificial Intelligence Laboratory, 32 Vassar Street, Cambridge, MA 02139 (United States)

    2016-09-20

    Images of the linear polarizations of synchrotron radiation around active galactic nuclei (AGNs) highlight their projected magnetic field lines and provide key data for understanding the physics of accretion and outflow from supermassive black holes. The highest-resolution polarimetric images of AGNs are produced with Very Long Baseline Interferometry (VLBI). Because VLBI incompletely samples the Fourier transform of the source image, any image reconstruction that fills in unmeasured spatial frequencies will not be unique and reconstruction algorithms are required. In this paper, we explore some extensions of the Maximum Entropy Method (MEM) to linear polarimetric VLBI imaging. In contrast to previous work, our polarimetric MEM algorithm combines a Stokes I imager that only uses bispectrum measurements that are immune to atmospheric phase corruption, with a joint Stokes Q and U imager that operates on robust polarimetric ratios. We demonstrate the effectiveness of our technique on 7 and 3 mm wavelength quasar observations from the VLBA and simulated 1.3 mm Event Horizon Telescope observations of Sgr A* and M87. Consistent with past studies, we find that polarimetric MEM can produce superior resolution compared to the standard CLEAN algorithm, when imaging smooth and compact source distributions. As an imaging framework, MEM is highly adaptable, allowing a range of constraints on polarization structure. Polarimetric MEM is thus an attractive choice for image reconstruction with the EHT.

  14. Modeling Phase-Aligned Gamma-Ray and Radio Millisecond Pulsar Light Curves

    Science.gov (United States)

    Venter, C.; Johnson, T.; Harding, A.

    2012-01-01

    Since the discovery of the first eight gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope, this population has been steadily expanding. Four of the more recent detections, PSR J00340534, PSR J1939+2134 (B1937+21; the first MSP ever discovered), PSR J1959+2048 (B1957+20; the first discovery of a black widow system), and PSR J2214+3000, exhibit a phenomenon not present in the original discoveries: nearly phase-aligned radio and gamma-ray light curves (LCs). To account for the phase alignment, we explore models where both the radio and gamma-ray emission originate either in the outer magnetosphere near the light cylinder or near the polar caps. Using a Markov Chain Monte Carlo technique to search for best-fit model parameters, we obtain reasonable LC fits for the first three of these MSPs in the context of altitude-limited outer gap (alOG) and two-pole caustic (alTPC) geometries (for both gamma-ray and radio emission). These models differ from the standard outer gap (OG)/two-pole caustic (TPC) models in two respects: the radio emission originates in caustics at relatively high altitudes compared to the usual conal radio beams, and we allow both the minimum and maximum altitudes of the gamma-ray and radio emission regions to vary within a limited range (excluding the minimum gamma-ray altitude of the alTPC model, which is kept constant at the stellar radius, and that of the alOG model, which is set to the position-dependent null charge surface altitude). Alternatively, phase-aligned solutions also exist for emission originating near the stellar surface in a slot gap scenario (low-altitude slot gap (laSG) models). We find that the alTPC models provide slightly better LC fits than the alOG models, and both of these give better fits than the laSG models (for the limited range of parameters considered in the case of the laSG models). Thus, our fits imply that the phase-aligned LCs are likely of caustic origin, produced in the outer magnetosphere, and

  15. MODELING PHASE-ALIGNED GAMMA-RAY AND RADIO MILLISECOND PULSAR LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Venter, C. [Centre for Space Research, North-West University, Potchefstroom Campus, Potchefstroom 2520 (South Africa); Johnson, T. J.; Harding, A. K. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-01-01

    Since the discovery of the first eight gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope, this population has been steadily expanding. Four of the more recent detections, PSR J0034-0534, PSR J1939+2134 (B1937+21; the first MSP ever discovered), PSR J1959+2048 (B1957+20; the first discovery of a black widow system), and PSR J2214+3000, exhibit a phenomenon not present in the original discoveries: nearly phase-aligned radio and gamma-ray light curves (LCs). To account for the phase alignment, we explore models where both the radio and gamma-ray emission originate either in the outer magnetosphere near the light cylinder or near the polar caps. Using a Markov Chain Monte Carlo technique to search for best-fit model parameters, we obtain reasonable LC fits for the first three of these MSPs in the context of 'altitude-limited' outer gap (alOG) and two-pole caustic (alTPC) geometries (for both gamma-ray and radio emission). These models differ from the standard outer gap (OG)/two-pole caustic (TPC) models in two respects: the radio emission originates in caustics at relatively high altitudes compared to the usual conal radio beams, and we allow both the minimum and maximum altitudes of the gamma-ray and radio emission regions to vary within a limited range (excluding the minimum gamma-ray altitude of the alTPC model, which is kept constant at the stellar radius, and that of the alOG model, which is set to the position-dependent null charge surface altitude). Alternatively, phase-aligned solutions also exist for emission originating near the stellar surface in a slot gap scenario ('low-altitude slot gap' (laSG) models). We find that the alTPC models provide slightly better LC fits than the alOG models, and both of these give better fits than the laSG models (for the limited range of parameters considered in the case of the laSG models). Thus, our fits imply that the phase-aligned LCs are likely of caustic origin, produced in the

  16. Target detection and recognition with polarimetric SAR

    NARCIS (Netherlands)

    Dekker, R.J.; Broek, A.C. van den

    2000-01-01

    Target detection and recognition using polarimetric SAR data has been studied by using PHARUS and RAMSES data collected during the MIMEX campaign. Additionally very high-resolution ISAR data was used. A basic detection and recognition scheme has been developed, which includes polarimetric

  17. Comparison of polarimetric cameras

    Science.gov (United States)

    2017-03-01

    and darker objects will have higher degrees of polarization. Quantitative data has been collected on the moon that displays the UMOV effect for...different phases and regions of the moon (Zubko 2011). The effect relates the wavelength, color, and texture of an object to polarization. C. NON-OPTICAL...and registering the photos after saving them. If the trigger mode was unsuccessful the images results cause errors in registration. An attempt at

  18. Atmospheric polarimetric effects on GNSS radio occultations: the ROHP-PAZ field campaign

    Science.gov (United States)

    Padullés, R.; Cardellach, E.; de la Torre Juárez, M.; Tomás, S.; Turk, F. J.; Oliveras, S.; Ao, C. O.; Rius, A.

    2016-01-01

    This study describes the first experimental observations showing that hydrometeors induce polarimetric signatures in global navigation satellite system (GNSS) signals. This evidence is relevant to the PAZ low Earth orbiter, which will test the concept and applications of polarimetric GNSS radio occultation (RO) (i.e. ROs obtained with a dual-polarization antenna). A ground field campaign was carried out in preparation for PAZ to verify the theoretical sensitivity studies on this concept (Cardellach et al., 2015). The main aim of the campaign is to identify and understand the factors that might affect the polarimetric GNSS observables. Studied for the first time, GNSS signals measured with two polarimetric antennas (H, horizontal, and V, vertical) are shown to discriminate between heavy rain events by comparing the measured phase difference between the H and V phase delays (ΔΦ) in different weather scenarios. The measured phase difference indicates higher dispersion under rain conditions. When individual events are examined, significant increases in ΔΦ occur when the radio signals cross rain cells. Moreover, the amplitude of such a signal is much higher than the theoretical prediction for precipitation; thus, other sources of polarimetric signatures have been explored and identified. Modelling of other hydrometeors, such as melting particles and ice crystals, have been proposed to explain the obtained measurements, with good agreement in more than 90 % of the cases.

  19. Polarimetric signatures of sea ice. 1: Theoretical model

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structral, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarmetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies to interpretation of sea ice polarimetric signatures.

  20. Analysis of the Ankle Moment-Angle Curve in Different Gait Speeds and Phases for Designing Ankle-Foot Prosthesis

    Directory of Open Access Journals (Sweden)

    Zahra Safaei-Pour

    2014-01-01

    Full Text Available Objective: Aim of this study was to analysis the ankle moment-angle relation and its characteristics at different gait speeds and phases for using in prosthetic ankle-foot design. Materials & Methods: This was a cross-sectional analytic study in which 20 participants were chosen with assessable sampling method. Gait analysis at different speeds was performed with two force-plates and five high speed cameras. Ankle characteristics including quasi-stiffness and work were estimated at three periods of stance phase based on moment-angle loop. Mean differences were analyzed with repeated measure ANOVA and regression analysis was performed to fit the linear model to the data. Results: Moment-angle curve was clockwise at slower speeds and turned counter-clockwise while speed increased. The best fitted line to the work-walking speed curve had R2=0.81. There were significant differences in quasi-stiffness between fast and normal speed and slower speeds (P<0.001. Conclusion: Moment-angle curve displayed ankle passive function in slower speeds and active function in faster speeds. Results showed ankle characteristics varied at different gait phases and speeds. Thus, at slower speeds a spring-damper model with regulable damping would simulate the ankle function. However, at higher speeds the active elements also should be considered.

  1. The ROHP-PAZ mission and the polarimetric and non-polarimetric effects of rain and other fozen hydrometeors on GNSS Radio-Occultation signals.

    Science.gov (United States)

    De La Torre Juarez, M.; Padulles, R.; Cardellach, E.; Tomás, S.; Turk, J.; Ao, C. O.; Oliveras, S.; Rius, A.

    2015-12-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) will test, for the first time, the new polarimetric radio occultation (RO) concept. This is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) RO payload on board of the Spanish Earth Observation satellite PAZ. The launch of the satellite is scheduled for October 2015, and it will be followed by a 6-month commissioning phase period and has an expected life of 7 years, with a goal of 10 years.The concept is similar to that used in some polarimetric weather radars: to measure the differential phase shift between the two polarimetric components of the received signal, although in this case we will use the forward scattering geometry instead of the backscattering one. It will allow us to retrieve precipitation and other hydrometeors information, and simultaneous thermodynamic vertical profiles which will help to the understanding of the thermodynamic processes beyond heavy rain events. A sensitivity analysis has been performed, showing that the rain-induced effect is above PAZ detectability threshold in 90% of the events with along-ray averaged rain rate higher than 5 mm/h. Also, a ground field campaign has been conducted prior to the launch of the satellite. The measurements from the campaign have shown the first experimental evidences that precipitation and frozen hydrometeors induce a noticeable effect into the polarimetric RO observables. We will present here the actual status of the mission and the results from the field campaign. We will also discuss the results of the theoretical study of the thermodynamics and the effects of rain and frozen hydrometeors into standard and polarimetric RO, based on a large collocation exercise of COSMIC and TerrasSar-X with TRMM, GPM and CloudSat.

  2. Link between interplanetary & cometary dust: Polarimetric observations and space studies with Rosetta & Eye-Sat

    Science.gov (United States)

    Levasseur-Regourd, Anny-Chantal; Gaboriaud, Alain; Buil, Christian; Ressouche, Antoine; Lasue, J.; Palun, Adrien; Apper, Fabien; Elmaleh, Marc

    Intensity and linear polarization observations of the solar light scattered by interplanetary dust, the so-called zodiacal light, provide information on properties of the dust particles, such as their spatial density, local changes, morphology and albedo. Earth-based polarimetric observations, with a resolution of 5° or more, have been used to derive the polarization phase curve of interplanetary dust particles and to establish that the polarization at 90° phase angle increases with increasing solar distance, at least up to 1.5 au in the ecliptic, while the albedo decreases [1, 2]. Analysis of such studies will be revisited. Numerical simulations of the polarimetric behavior of interplanetary dust particles strongly suggest that, in the inner solar system, interplanetary dust particles consist of absorbing (e.g., organic compounds) and less absorbing (e.g., silicates) materials, that radial changes originate in a decrease of organics with decreasing solar distance (probably due to alteration processes), and that a significant fraction of the interplanetary dust is of cometary origin, in agreement with dynamical studies [3, 4]. The polarimetric behaviors of interplanetary dust and cometary dust particles seem to present striking similarities. The properties of cometary dust particles, as derived from remote polarimetric observations of comets including 67P/Churyumov-Gerasimenko, the target of the Rosetta rendezvous mission, at various wavelengths, will be summarized [5, 6]. The ground truth expected from Rosetta dust experiments, i.e., MIDAS, COSIMA, GIADA, about dust particles’ morphology, composition, and evolution (with distance to the nucleus before Philae release and with distance to the Sun before and after perihelion passage) over the year and a half of nominal mission, will be discussed. Finally, the Eye-Sat nanosatellite will be presented. This triple cubesat, developed by students from engineering schools working as interns at CNES, is to be launched

  3. ICP curve morphology and intracranial flow-volume changes: a simultaneous ICP and cine phase contrast MRI study in humans.

    Science.gov (United States)

    Unnerbäck, Mårten; Ottesen, Johnny T; Reinstrup, Peter

    2018-02-01

    The intracranial pressure (ICP) curve with its different peaks has been extensively studied, but the exact physiological mechanisms behind its morphology are still not fully understood. Both intracranial volume change (ΔICV) and transmission of the arterial blood pressure have been proposed to shape the ICP curve. This study tested the hypothesis that the ICP curve correlates to intracranial volume changes. Cine phase contrast magnetic resonance imaging (MRI) examinations were performed in neuro-intensive care patients with simultaneous ICP monitoring. The MRI was set to examine cerebral arterial inflow and venous cerebral outflow as well as flow of cerebrospinal fluid over the foramen magnum. The difference in total flow into and out from the cranial cavity (Flow tot ) over time provides the ΔICV. The ICP curve was compared to the Flow tot and the ΔICV. Correlations were calculated through linear and logarithmic regression. Student's t test was used to test the null hypothesis between paired samples. Excluding the initial ICP wave, P1, the mean R 2 for the correlation between the ΔICV and the ICP was 0.75 for the exponential expression, which had a higher correlation than the linear (p = 0.005). The first ICP peaks correlated to the initial peaks of Flow tot with a mean R 2  = 0.88. The first part, or the P1, of the ICP curve seems to be created by the first rapid net inflow seen in Flow tot while the rest of the ICP curve seem to correlate to the ΔICV.

  4. Is the caloric curve a robust signal of the phase transition in hot nuclei?

    Science.gov (United States)

    Vient, E.

    2017-11-01

    The richness of the data set, collected by the INDRA Collaboration during the last twenty years, enabled us to build a set of caloric curves for nuclei of various sizes, by using, for the first time, a single experimental set-up and a single experimental protocol. We will therefore present the different caloric curves ( E^{\\ast}-T obtained by a new calorimetry, for Quasi-Projectiles produced by symmetric or quasi symmetric reactions at different incident energies (Au + Au, Xe + Sn, Ni + Ni). For all these systems, a clear change of the de-excitation process of hot nuclei is observed but this one is neither a plateau nor a back-bending, but a sudden change of slope.

  5. ASTEROID POLARIMETRIC DATABASE V6.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  6. ASTEROID POLARIMETRIC DATABASE V7.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  7. ASTEROID POLARIMETRIC DATABASE V8.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  8. ASTEROID POLARIMETRIC DATABASE V5.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  9. Polarimetric Emission of Rain Events: Simulation and Experimental Results at X-Band

    Directory of Open Access Journals (Sweden)

    Nuria Duffo

    2009-06-01

    Full Text Available Accurate models are used today for infrared and microwave satellite radiance simulations of the first two Stokes elements in the physical retrieval, data assimilation etc. of surface and atmospheric parameters. Although in the past a number of theoretical and experimental works have studied the polarimetric emission of some natural surfaces, specially the sea surface roughened by the wind (Windsat mission, very limited studies have been conducted on the polarimetric emission of rain cells or other natural surfaces. In this work, the polarimetric emission (four Stokes elements of a rain cell is computed using the polarimetric radiative transfer equation assuming that raindrops are described by Pruppacher-Pitter shapes and that their size distribution follows the Laws-Parsons law. The Boundary Element Method (BEM is used to compute the exact bistatic scattering coefficients for each raindrop shape and different canting angles. Numerical results are compared to the Rayleigh or Mie scattering coefficients, and to Oguchi’s ones, showing that above 1-2 mm raindrop size the exact formulation is required to model properly the scattering. Simulation results using BEM are then compared to the experimental data gathered with a X-band polarimetric radiometer. It is found that the depolarization of the radiation caused by the scattering of non-spherical raindrops induces a non-zero third Stokes parameter, and the differential phase of the scattering coefficients induces a non-zero fourth Stokes parameter.

  10. Circadian phase response curves to light in older and young women and men

    Directory of Open Access Journals (Sweden)

    Rex Katharine M

    2007-07-01

    Full Text Available Abstract Background The phase of a circadian rhythm reflects where the peak and the trough occur, for example, the peak and trough of performance within the 24 h. Light exposure can shift this phase. More extensive knowledge of the human circadian phase response to light is needed to guide light treatment for shiftworkers, air travelers, and people with circadian rhythm phase disorders. This study tested the hypotheses that older adults have absent or weaker phase-shift responses to light (3000 lux, and that women's responses might differ from those of men. Methods After preliminary health screening and home actigraphic recording baselines, 50 young adults (ages 18–31 years and 56 older adults (ages 59–75 years remained in light-controlled laboratory surroundings for 4.7 to 5.6 days, while experiencing a 90-min ultra-short sleep-wake cycle. Following at least 30 h in-lab baseline, over the next 51 h, participants were given 3 treatments with 3000 lux white light, each treatment for 3 h, centered at one of 8 clock times. The circadian rhythms of urinary aMT6s (a melatonin metabolite, free cortisol, oral temperature, and wrist activity were assessed at baseline and after treatment. Results Light (3000 lux for 3 h on 3 days induced maximal phase shifts of about 3 h. Phase shifts did not differ significantly in amplitude among older and young groups or among women and men. At home and at baseline, compared to the young, the older adults were significantly phase-advanced in sleep, cortisol, and aMT6s onset, but not advanced in aMT6s acrophase or the temperature rhythm. The inflection from delays to advances was approximately 1.8 h earlier among older compared to young participants in reference to their aMT6s rhythm peaks, and it was earlier in clock time. Conclusion In these experimental conditions, 3000 lux light could shift the phase of circadian rhythms to about the same extent among older and young adults, but the optimal light timing for

  11. HD 240121 - An ACV variable showing anti-phase variations of the B and V light curves

    Science.gov (United States)

    Gröbel, Rainer; Hümmerich, Stefan; Paunzen, Ernst; Bernhard, Klaus

    2017-01-01

    The variability of HD 240121 = BD+59 2602 was first suspected by Särg and Wramdemark (1970) and later confirmed by Gröbel R. (1992a,b). Because of the observed anti-phase variations of the B and V light curves, the latter author tentatively suggested an ACV type. Apart from its inclusion in the catalog of New Suspected Variables (NSV 25977), no further investigations of the star have been published. HD 240121 was included into our target list of ACV candidates and investigated in order to determine the reason for the observed brightness variations. All available information on HD 240121 were collected via an exhaustive data mining procedure. Data from Gröbel (1992a,b) were re-analysed and photometric observations from the NSVS and Hipparcos archives were procured and investigated. Line-of-sight reddening and stellar parameters were calculated from archival photometric data. HD 240121 is a young, late B-type CP2 star of the silicon subgroup. The observed period, amplitude of light variations and variability pattern (anti-phase variations) are typical of ACV variables. The occurrence of anti-phase variations of the B and V light curves is rarely observed and points to the existence of a null wavelength in the visual spectrum. We therefore strongly encourage further multi-colour photometric observations of this star.

  12. Polarimetric and Interferometric Synthetic Aperture Radar (Pol-InSAR); a new way to quantify three-dimensional structure of Earth and planetary surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This study will employ a three phased approach: SAR image formation and calibration. DBSAR polarimetric and interferometric data analysis. PolInSAR algorithm...

  13. Some OFDM waveforms for a fully polarimetric weather radar

    NARCIS (Netherlands)

    Van Genderen, P.; Krasnov, O.A.; Wang, Z.; Tigrek, R.F.

    2012-01-01

    Retrieval of cloud parameters in weather radar benefits from polarimetric measurements. Most polarimetric radars measure the full backscatter matrix (BSM) using a few alternating polarized sounding signals. Using specially encoded orthogonal frequency division multiplexing (OFDM) signals however,

  14. Evaluation of diastolic phase by left ventricular volume curve using s2-gated equilibrium method among radioisotope angiography

    International Nuclear Information System (INIS)

    Watanabe, Yoshirou; Sakai, Akira; Inada, Mitsuo; Shiraishi, Tomokuni; Kobayashi, Akitoshi

    1982-01-01

    S2-gated (the second heart sound) method was designed by authors. In 6 normal subjects and 16 patients (old myocardial infarction 12 cases, hypertension 2 cases and aortic regurgitation 2 cases), radioisotope (RI) angiography using S2-gated equilibrium method was performed. In RI angiography, sup(99m)Tc-human serum albumin (HSA) 555MBq (15mCi) as tracer, PDP11/34 as minicomputer and PCG/ECG symchromizer (Metro Inst.) were used. Then left ventricular (LV) volume curve by S2-gated and electrocardiogram (ECG) R wave-gated method were obtained. Using LV volume curve, left ventricular ejection fraction (EF), mean ejection rate (mER, s -1 ), mean filling rate (mFR, -1 ) and rapid filling fraction (RFF) were calculated. mFR indicated mean filling rate during rapid filling phase. RFF was defined as the filling fraction during rapid filling phase among stroke volume. S2-gated method was reliable in evaluation of early diastolic phase, compared with ECG-gated method. There was the difference between RFF in normal group and myocardial infarction (MI) group (p < 0.005). RFF in 2 groups were correlated with EF (r = 0.82, p < 0.01). RFF was useful in evaluating MI cases who had normal EF values. The comparison with mER by ECG-gated and mFR by S2-gated was useful in evaluating MI cases who had normal mER values. mFR was remarkably lower than mER in MI group, but was equal to mER in normal group approximately. In conclusion, the evaluation using RFF and mFR by S2-gated method was useful in MI cases who had normal systolic phase indices. (author)

  15. Heavy Rainfall Monitoring by Polarimetric C-Band Weather Radars

    Directory of Open Access Journals (Sweden)

    Roberto Cremonini

    2010-11-01

    Full Text Available Piemonte region, in the north-western Italy, is characterized by complex orography and Mediterranean influence that often causes extreme rainfall event, during the warm season. Although the region is monitored by a dense gauge network (more than one gauge per 100 km2, the ground measurements are often inadequate to properly observe intense and highly variable precipitations. Polarimetric weather radars provide a unique way to monitor rainfall over wide areas, with the required spatial detail and temporal resolution. Nevertheless, most European weather radar networks are operating at C-band, which may seriously limit quantitative precipitation estimation in heavy rainfall due to relevant power signal attenuation. Phase measurements, unlike power measurements, are not affected by signal attenuation. For this reason, polarimetric radars, for which the differential phase shift measurements are available, provide an additional way in which to estimate precipitation, which is immune to signal attenuation. In this work differential phase based rainfall estimation techniques are applied to analyze two flash-floods: the first one occurred on the Ligurian Apennines on 16 August 2006 and the second occurred on 13 September 2008, causing rain accumulations above 270 mm in few hours.

  16. Reducing radiation dose in grating based x-ray phase contrast CT with twin-peaks in its phase stepping curves.

    Science.gov (United States)

    Xie, Huiqiao; Cai, Weixing; Yang, Lily; Mao, Hui; Tang, Xiangyang

    2016-11-01

    Differential phase contrast CT has been recognized as an x-ray imaging method with the potential to greatly improve the differentiation of soft tissues. Talbot interferometry has been one of the promising solutions allowing implementation with commercially available x-ray tubes with a polychromatic spectrum. Mainly due to imperfections in grating fabrication and the polychromatic spectrum of x-ray beam, a twin-peaks phenomenon may exist in phase stepping curves (PSCs) and degrade the performance of phase retrieval. The authors have previously proposed a Fourier analysis based method for phase retrieval in the scenario wherein the twin-peaks phenomenon occurs in PSCs. In this work, the authors propose a 5-step algebraic method for phase retrieval and investigate the potential of reducing radiation dose while both the Fourier and algebraic methods are being utilized for phase retrieval. The algebraic method to deal with the twin-peaks phenomenon, in which a set of linear equations with five unknown variables is needed for phase retrieval, is an extension of the so-called 3-step method that has been used in the scenario wherein only single-peak exists in the PSCs. In addition to a numerical phantom, two sets of experimental data (a phantom made of organic materials and a small animal) acquired by a prototype differential phase contrast CT system are employed to evaluate the performance of the Fourier and algebraic phase retrieval methods and their potential in radiation dose reduction. The evaluation by both numerical phantom and experimental data shows that the algebraic method works as well as the Fourier method in phase retrieval if the twin-peaks phenomenon in the PSCs is appropriately dealt with. In addition, while the radiation dose associated with data acquisition is being reduced via fewer phase shifting steps, the algebraic method can maintain a better performance compared to the Fourier method. Along with the Fourier method, the proposed 5-step algebraic

  17. Spitzer Phase Curve Constraints for WASP-43b at 3.6 and 4.5 μm

    Science.gov (United States)

    Stevenson, Kevin B.; Line, Michael R.; Bean, Jacob L.; Désert, Jean-Michel; Fortney, Jonathan J.; Showman, Adam P.; Kataria, Tiffany; Kreidberg, Laura; Feng, Y. Katherina

    2017-02-01

    Previous measurements of heat redistribution efficiency (the ability to transport energy from a planet’s highly irradiated dayside to its eternally dark nightside) show considerable variation between exoplanets. Theoretical models predict a positive correlation between heat redistribution efficiency and temperature for tidally locked planets; however, recent Hubble Space Telescope (HST) WASP-43b spectroscopic phase curve results are inconsistent with current predictions. Using the Spitzer Space Telescope, we obtained a total of three phase curve observations of WASP-43b (P = 0.813 days) at 3.6 and 4.5 μm. The first 3.6 μm visit exhibits spurious nightside emission that requires invoking unphysical conditions in our cloud-free atmospheric retrievals. The two other visits exhibit strong day-night contrasts that are consistent with the HST data. To reconcile the departure from theoretical predictions, WASP-43b would need to have a high-altitude, nightside cloud/haze layer blocking its thermal emission. Clouds/hazes could be produced within the planet’s cool, nearly retrograde mid-latitude flows before dispersing across its nightside at high altitudes. Since mid-latitude flows only materialize in fast-rotating (≲ 1 day) planets, this may explain an observed trend connecting measured day-night contrast with planet rotation rate that matches all current Spitzer phase curve results. Combining independent planetary emission measurements from multiple phases, we obtain a precise dayside hemisphere H2O abundance (2.5× {10}-5{--}1.1× {10}-4 at 1σ confidence) and, assuming chemical equilibrium and a scaled solar abundance pattern, we derive a corresponding metallicity estimate that is consistent with being solar (0.4-1.7). Using the retrieved global CO+CO2 abundance under the same assumptions, we estimate a comparable metallicity of 0.3-1.7× solar. This is the first time that precise abundance and metallicity constraints have been determined from multiple molecular

  18. Polarimetric synthetic aperture radar application for tropical peatlands classification: a case study in Siak River Transect, Riau Province, Indonesia

    Science.gov (United States)

    Novresiandi, Dandy Aditya; Nagasawa, Ryota

    2017-01-01

    Mapping spatial distributions of tropical peatlands is important for properly estimating carbon emissions and for providing information that aids in the sustainable management of tropical peatlands, particularly in Indonesia. This study evaluated the performance of phased array type L-band synthetic aperture radar (SAR) (PALSAR) dual-polarization and fully polarimetric data for tropical peatlands classification. The study area was in Siak River Transect, Riau Province, Indonesia, a rapidly developing region, where the peatland has been intensively converted mostly into oil palm plantations over the last two decades. Thus, polarimetric features derived after polarimetric decompositions, backscatter coefficients measurements, and the radar vegetation index were evaluated to classify tropical peatlands using the decision tree classifier. Overall, polarimetric features generated by the combination of dual-polarization and fully polarimetric data yielded an overall accuracy (OA) of 69% and a kappa coefficient (K) of 0.57. The integration of an additional feature, "distance to river," to the algorithm increased the OA to 76% and K to 0.66. These results indicated that the methodology in this study might serve as an efficient tool in tropical peatlands classification, especially when involving the use of L-band SAR dual-polarization and fully polarimetric data.

  19. Land Cover Changes Detection in Polarimetric SAR Data Using Algebra, Similarity and Distance Based Methods

    Science.gov (United States)

    Najafi, A.; Hasanlou, M.; Akbari, V.

    2017-09-01

    Monitoring and surveillance changes around the world need powerful methods, so detection, visualization, and assessment of significant changes are essential for planning and management. Incorporating polarimetric SAR images due to interactions between electromagnetic waves and target and because of the high spatial resolution almost one meter can be used to study changes in the Earth's surface. Full polarized radar images comparing to single polarized radar images use amplitude and phase information of the surface in different available polarization (HH, HV, VH, and VV). This study is based on the decomposition of full polarized airborne UAVSAR images and integration of these features with algebra method involves Image Differencing (ID) and Image Ratio (IR) algorithms with the mathematical nature and distance-based method involves Canberra (CA) and Euclidean (ED) algorithms with measuring distance between corresponding vector and similarity-based method involves Taminoto (TA) and Kulczynski (KU) algorithms with dependence corresponding vector for change detecting purposes on two real PolSAR datasets. Assessment of incorporated methods is implemented using ground truth data and different criteria for evaluating such as overall accuracy (OA), area under ROC curve (AUC) and false alarms rate (FAR). The output results show that ID, IR, and CA have superiority to detect changes comparing to other implemented algorithms. Also, numerical results show that the highest performance in two datasets has OA more than 90%. In other assessment criteria, mention algorithms have low FAR and high AUC value indices to detect changes in PolSAR images.

  20. Polarimetric radar characteristics of storms with and without lightning activity

    Science.gov (United States)

    Mattos, Enrique V.; Machado, Luiz A. T.; Williams, Earle R.; Albrecht, Rachel I.

    2016-12-01

    This paper analyzes the cloud microphysics in different layers of storms as a function of three-dimensional total lightning density. A mobile X-band polarimetric radar and very high frequency (VHF) sources from Lightning Mapping Array (LMA) observations during the 2011/2012 Brazil spring-summer were used to determine the microphysical signatures of radar vertical profiles and lightning density. This study quantified the behavior of 5.3 million vertical profiles of the horizontal reflectivity (ZH), differential reflectivity (ZDR), specific differential phase (KDP), and correlation coefficient (ρHV). The principal changes in the polarimetric variables occurred only for VHF source rate density greater than 14 VHF sources per km2 in 4 min. These storms showed an enhanced positive KDP in the mixed 1 layer (from 0 to -15°C) probably associated with supercooled liquid water signatures, whereas regions with negative ZDR and KDP and moderate ZH in the mixed 2 layer (from -15 to -40°C) were possibly associated with the presence of conical graupel. The glaciated (above -40°C) and upper part of the mixed 2 layers showed a significant trend to negative KDP with an increase in lightning density, in agreement with vertical alignment of ice particle by the cloud electric field. A conceptual model that presents the microphysical signatures in storms with and without lightning activity was constructed. The observations documented in this study provide an understanding of how the combinations of polarimetric variables could help to identify storms with different lightning density and vice versa.

  1. A new approach for determining phase response curves reveals that Purkinje cells can act as perfect integrators.

    Directory of Open Access Journals (Sweden)

    Elena Phoka

    2010-04-01

    Full Text Available Cerebellar Purkinje cells display complex intrinsic dynamics. They fire spontaneously, exhibit bistability, and via mutual network interactions are involved in the generation of high frequency oscillations and travelling waves of activity. To probe the dynamical properties of Purkinje cells we measured their phase response curves (PRCs. PRCs quantify the change in spike phase caused by a stimulus as a function of its temporal position within the interspike interval, and are widely used to predict neuronal responses to more complex stimulus patterns. Significant variability in the interspike interval during spontaneous firing can lead to PRCs with a low signal-to-noise ratio, requiring averaging over thousands of trials. We show using electrophysiological experiments and simulations that the PRC calculated in the traditional way by sampling the interspike interval with brief current pulses is biased. We introduce a corrected approach for calculating PRCs which eliminates this bias. Using our new approach, we show that Purkinje cell PRCs change qualitatively depending on the firing frequency of the cell. At high firing rates, Purkinje cells exhibit single-peaked, or monophasic PRCs. Surprisingly, at low firing rates, Purkinje cell PRCs are largely independent of phase, resembling PRCs of ideal non-leaky integrate-and-fire neurons. These results indicate that Purkinje cells can act as perfect integrators at low firing rates, and that the integration mode of Purkinje cells depends on their firing rate.

  2. Mathematical modeling of two phase stratified flow in a microchannel with curved interface

    Science.gov (United States)

    Dandekar, Rajat; Picardo, Jason R.; Pushpavanam, S.

    2017-11-01

    Stratified or layered two-phase flows are encountered in several applications of microchannels, such as solvent extraction. Assuming steady, unidirectional creeping flow, it is possible to solve the Stokes equations by the method of eigenfunctions, provided the interface is flat and meets the wall with a 90 degree contact angle. However, in reality the contact angle depends on the pair of liquids and the material of the channel, and differs significantly from 90 degrees in many practical cases. For unidirectional flow, this implies that the interface is a circular arc (of constant curvature). We solve this problem within the framework of eigenfunctions, using the procedure developed by Shankar. We consider two distinct cases: (a) the interface meets the wall with the equilibrium contact angle; (b) the interface is pinned by surface treatment of the walls, so that the flow rates determine the apparent contact angle. We show that the contact angle appreciably affects the velocity profile and the volume fractions of the liquids, while limiting the range of flow rates that can be sustained without the interface touching the top/bottom walls. Non-intuitively, we find that the pressure drop is reduced when the more viscous liquid wets the wall.

  3. Science data collection with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Woelders, Kim; Madsen, Søren Nørvang

    1996-01-01

    Discusses examples on the use of polarimetric SAR in a number of Earth science studies. The studies are presently being conducted by the Danish Center for Remote Sensing. A few studies of the European Space Agency's EMAC programme are also discussed. The Earth science objectives are presented......, and the potential of polarimetric SAR is discussed and illustrated with data collected by the Danish airborne EMISAR system during a number of experiments in 1994 and 1995. The presentation will include samples of data acquired for the different studies...

  4. Millimeter Wave Polarimetric Radar Remote Sensing of Ice Clouds.

    Science.gov (United States)

    Tang, Chengxian

    Ice clouds play important roles in many practical and theoretical researches. This thesis investigates the electromagnetic scattering properties of ice crystals at 94 and 220 GHz, and polarimetric radar techniques for ice crystal type discrimination and ice mass content estimation. The scattering amplitude matrix is computed for pristine ice crystals of different sizes and from different incidence directions using the Finite Difference Time Domain method. Hexagonal plates, stellar crystals, and hexagonal columns with empirical aspect ratios are considered. The results show that the co-polarized scattering amplitudes are not sensitive to the azimuthal incidence angle but dependent on the polar incidence angle theta as functions of costheta or sintheta raised to a power which depends on particle size. Cross-polarized scattering amplitudes are negligible when the wave polarization is aligned with respect to the particle symmetry axis. Numerical computations are performed to examine the dependence of polarimetric radar parameters on the parameters in the gamma size and Gaussian canting angle distributions, and on radar elevation angle. The computed Mueller matrix elements related to the cross-correlation of the co-polarized and cross-polarized scattering amplitudes are less than 5% of the total irradiance. The linear depolarization ratio, circular depolarization ratio, and dual-frequency ratio are found depolarization ratio, circular depolarization ratio, and dual-frequency ratio are found useful for differentiating between planar ice crystals and columns. Five relationships between ice mass content and polarimetric radar parameters are derived based on numerical simulations representing various assumed ice mass contents and gamma size distributions. The specific differential phase at incidence angles away from the zenith, and effective reflectivity factor together with dual-frequency ratio can provide reasonable estimates for ice mass content. Simulations based on in

  5. Polarimetric survey of main-belt asteroids⋆. III. Results for 33 X-type objects

    Science.gov (United States)

    Cañada-Assandri, M.; Gil-Hutton, R.; Benavidez, P.

    2012-06-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15 m telescope. The Torino polarimeter is an instrument that allows the simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data of a sample of more than 170 asteroids were obtained. In this paper the results for 33 X-type objects are presented, several of them are being polarimetrically observed for the first time. Using these data we found polarization curves and polarimetric parameters for different groups among this taxonomic class and that there are objects with very different albedo in the sub-classes of the X taxonomic complex. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A11

  6. A SEMI-ANALYTICAL MODEL OF VISIBLE-WAVELENGTH PHASE CURVES OF EXOPLANETS AND APPLICATIONS TO KEPLER- 7 B AND KEPLER- 10 B

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Renyu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Demory, Brice-Olivier [Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Seager, Sara; Lewis, Nikole [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Showman, Adam P., E-mail: renyu.hu@jpl.nasa.gov [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States)

    2015-03-20

    Kepler has detected numerous exoplanet transits by measuring stellar light in a single visible-wavelength band. In addition to detection, the precise photometry provides phase curves of exoplanets, which can be used to study the dynamic processes on these planets. However, the interpretation of these observations can be complicated by the fact that visible-wavelength phase curves can represent both thermal emission and scattering from the planets. Here we present a semi-analytical model framework that can be applied to study Kepler and future visible-wavelength phase curve observations of exoplanets. The model efficiently computes reflection and thermal emission components for both rocky and gaseous planets, considering both homogeneous and inhomogeneous surfaces or atmospheres. We analyze the phase curves of the gaseous planet Kepler- 7 b and the rocky planet Kepler- 10 b using the model. In general, we find that a hot exoplanet’s visible-wavelength phase curve having a significant phase offset can usually be explained by two classes of solutions: one class requires a thermal hot spot shifted to one side of the substellar point, and the other class requires reflective clouds concentrated on the same side of the substellar point. Particularly for Kepler- 7 b, reflective clouds located on the west side of the substellar point can best explain its phase curve. The reflectivity of the clear part of the atmosphere should be less than 7% and that of the cloudy part should be greater than 80%, and the cloud boundary should be located at 11° ± 3° to the west of the substellar point. We suggest single-band photometry surveys could yield valuable information on exoplanet atmospheres and surfaces.

  7. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; hide

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  8. Investigation of Polarimetric and Electrical Characteristics of Natural and Triggered Lightning Strikes

    Science.gov (United States)

    Hyland, P. T.; Biggerstaff, M. I.; Uman, M. A.; Jordan, D. M.; Hill, J. D.; Pilkey, J. T.; Ngin, T.; Blakeslee, R. J.; Krehbiel, P. R.; Rison, W.; Winn, W. P.; Eack, K.; Trueblood, J.; Edens, H. E.

    2013-12-01

    For the past three summers, the University of Oklahoma has deployed three mobile, polarimetric radars to the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida and Langmuir Laboratory near Socorro, New Mexico for the purpose of investigating the relationship between cloud structure and the propagation of triggered and natural lightning channels. This presentation will highlight observations from select natural and triggered events at these two facilities. During the summer of 2012, University of Oklahoma radar operators made a launch recommendation to the ICLRT during the passage of Tropical Storm Debby over northeast Florida that resulted in a successful triggered flash with 11 return strokes. The trigger was attempted as precipitation streamers within the stratiform rainbands of Tropical Storm Debby approached the launch site. According to the National Lightning Detection Network (NLDN), there were no reported natural cloud-to-ground (CG) flashes within 60 km of the ICLRT 20 hours before and eight hours after the triggered flash. The recommendation was made based on previous analyses of the storm structure of trigger attempts from the ICLRT that indicated the coincidence of several successful triggers with descending regions of enhanced radar reflectivity, or descending precipitation packets (DePPs). Polarimetric data from the frequency-agile Rapid-scanning X-band Polarimetric (RaXPol) radar as well as data from the lightning mapping array (LMA) and electric field meter (EFM) networks from the ICLRT for this event will be presented. Past analyses also revealed ice alignment signatures in differential phase and specific differential phase as strong electric fields near the top of electrified clouds cause small ice particles to become vertically aligned. These signatures are especially noticeable for circularly polarized radars. Polarimetric data from the Shared Mobile Atmospheric Research & Teaching (SMART) radar and Ra

  9. The joint inversion of phase dispersion curves and receiver functions at the margin of East European Craton

    Science.gov (United States)

    Chrapkiewicz, Kajetan; Wilde-Piórko, Monika; Polkowski, Marcin

    2017-04-01

    For the first time a joint inversion of Rayleigh-wave phase velocity dispersion curves and P receiver functions has been applied to study the south-western margin of East European Craton (EEC) in Poland. The area of investigation lies in the vicinity of Trans-European Suture Zone (TESZ) regarded as the most prominent lithospheric boundary in Europe separating the Precambrian EEC from assemblage of Phanerozoic-accreted terranes (e.g. Pharaoh, 1999). While the sedimentary and crystalline crust of EEC's margin has been precisely recognized with the borehole and refraction data compilation (Grad et al., 2016), the structure of lithosphere-asthenosphere boundary (LAB) underneath remains poorly understood. To address this issue, the passive seismic experiment „13 BB Star" (2013-2016) was carried out in northern Poland - just at the margin of EEC. For each station of „13 BB Star" network we obtained a credible 1-D shear-wave velocity model with linearized damped least-squares inversion (Herrmann, 2013) down to the depth of 250 km. The joint inversion of receiver functions and surface-wave dispersion curves has proved to be a natural approach when inferring the nature of cratonic LAB (e.g. Bodin et al., 2014). It's sensitive to both absolute velocities and sharp discontinuities and thus provides a better vertical resolution compared to surface wave data alone. The results indicate the presence of steady 4 per cent grow in the shear-wave velocity between 120 and 180 km depth and gradual 6 per cent drop over 180-220 km depth range. The latter may be interpreted as the LAB with depth and absolute-velocity change similar to those reported for other cratons (Kind et al., 2012). National Science Centre Poland provided financial support for this work by NCN grant DEC-2011/02/A/ST10/00284.

  10. Compact Polarimetric SAR Ship Detection with m-δ Decomposition Using Visual Attention Model

    Directory of Open Access Journals (Sweden)

    Lu Xu

    2016-09-01

    Full Text Available A few previous studies have illustrated the potentials of compact polarimetric Synthetic Aperture Radar (CP SAR in ship detection. In this paper, we design a ship detection algorithm of CP SAR from the perspective of computer vision. A ship detection algorithm using the pulsed cosine transform (PCT visual attention model is proposed to suppress background clutter and highlight conspicuous ship targets. It is the first time that a visual attention model is introduced to CP SAR application. The proposed algorithm is a quick and complete framework for practical use. Polarimetric features—the relative phase δ and volume scattering component—are extracted from m-δ decomposition to eliminate false alarms and modify the PCT model. The constant false alarm rate (CFAR algorithm based on lognormal distribution is adopted to detect ship targets, after a clutter distribution fitting procedure of the modified saliency map. The proposed method is then tested on three simulated circular-transmit-linear-receive (CTLR mode images, which covering East Sea of China. Compared with the detection results of SPAN and the saliency map with only single-channel amplitude, the proposed method achieves the highest detection rates and the lowest misidentification rate and highest figure of merit, proving the effectiveness of polarimetric information of compact polarimetric SAR ship detection and the enhancement from the visual attention model.

  11. Assessment of ex-vitro anaerobic digestion kinetics of crop residues through first order exponential models: effect of lag phase period and curve factor

    International Nuclear Information System (INIS)

    Sahito, A.R.; Brohi, K.M.

    2013-01-01

    Kinetic studies of AD (Anaerobic Digestion) process are useful to predict the performance of digesters and design appropriate digesters and also helpful in understanding inhibitory mechanisms of biodegradation. The aim of this study was to assess the anaerobic kinetics of crop residues digestion with buffalo dung. Seven crop residues namely, bagasse, banana plant waste, canola straw, cotton stalks, rice straw, sugarcane trash and wheat straw were selected from the field and were analyzed on MC (Moisture Contents), TS (Total Solids) and VS (Volatile Solids) with standard methods. In present study, three first order exponential models namely exponential model, exponential lag phase model and exponential curve factor model were used to assess the kinetics of the AD process of crop residues and the effect of lag phase and curve factor was analyzed based on statistical hypothesis testing and on information theory. Assessment of kinetics of the AD of crop residues and buffalo dung follows the first order kinetics. Out of the three models, the simple exponential model was the poorest model, while the first order exponential curve factor model is the best fit model. In addition to statistical hypothesis testing, the exponential curve factor model has least value of AIC (Akaike's Information Criterion) and can generate methane production data more accurately. Furthermore, there is an inverse linear relationship between the lag phase period and the curve factor. (author)

  12. Airborne polarimetric Doppler weather radar: trade-offs between various engineering specifications

    Science.gov (United States)

    Vivekanandan, Jothiram; Loew, Eric

    2018-01-01

    NCAR EOL is investigating potential configurations for the next-generation airborne phased array radar (APAR) that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. The APAR will operate at C band. The APAR will use the electronic scanning (e-scan) feature to acquire the optimal number of independent samples for recording research-quality measurements. Since the airborne radar has only a limited time for collecting measurements over a specified region (moving aircraft platform ˜ 100 m s-1), beam multiplexing will significantly enhance its ability to collect high-resolution, research-quality measurements. Beam multiplexing reduces errors in radar measurements while providing rapid updates of scan volumes. Beamwidth depends on the size of the antenna aperture. Beamwidth and directivity of elliptical, circular, and rectangular antenna apertures are compared and radar sensitivity is evaluated for various polarimetric configurations and transmit-receive (T/R) elements. In the case of polarimetric measurements, alternate transmit with alternate receive (single-channel receiver) and simultaneous reception (dual-channel receiver) is compared. From an overall architecture perspective, element-level digitization of T/R module versus digital sub-array is considered with regard to flexibility in adaptive beamforming, polarimetric performance, calibration, and data quality. Methodologies for calibration of the radar and removing bias in polarimetric measurements are outlined. The above-mentioned engineering options are evaluated for realizing an optimal APAR system suitable for measuring the high temporal and spatial resolutions of Doppler and polarimetric measurements of precipitation and clouds.

  13. SMEX02 Aircraft Polarimetric Scanning Radiometer (PSR) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The Polarimetric Scanning Radiometer (PSR) is an airborne microwave imaging radiometer developed and operated by the National Oceanic and Atmospheric Administration...

  14. IHW COMET HALLEY POLARIMETRIC OBSERVATIONS, V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains the polarimetric results reported to the International Halley Watch (IHW) Photometry and Polarimetry Network (PPN) by the various...

  15. CAMEX-3 POLARIMETRIC SCANNING RADIOMETER (PSR) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Polarimetric Scanning Radiometer (PSR) is a versatile airborne microwave imaging radiometer developed by the Georgia Institute of Technology and the NOAA...

  16. Polarimetric Radar Characteristics of Simulated and Observed Intense Convection Between Continental and Maritime Environment

    Science.gov (United States)

    Matsui, T.; Dolan, B.; Tao, W. K.; Rutledge, S. A.; Iguchi, T.; Barnum, J. I.; Lang, S. E.

    2017-12-01

    This study presents polarimetric radar characteristics of intense convective cores derived from observations as well as a polarimetric-radar simulator from cloud resolving model (CRM) simulations from Midlatitude Continental Convective Clouds Experiment (MC3E) May 23 case over Oklahoma and a Tropical Warm Pool-International Cloud Experiment (TWP-ICE) Jan 23 case over Darwin, Australia to highlight the contrast between continental and maritime convection. The POLArimetric Radar Retrieval and Instrument Simulator (POLARRIS) is a state-of-art T-matrix-Mueller-Matrix-based polarimetric radar simulator that can generate synthetic polarimetric radar signals (reflectivity, differential reflectivity, specific differential phase, co-polar correlation) as well as synthetic radar retrievals (precipitation, hydrometeor type, updraft velocity) through the consistent treatment of cloud microphysics and dynamics from CRMs. The Weather Research and Forecasting (WRF) model is configured to simulate continental and maritime severe storms over the MC3E and TWP-ICE domains with the Goddard bulk 4ICE single-moment microphysics and HUCM spectra-bin microphysics. Various statistical diagrams of polarimetric radar signals, hydrometeor types, updraft velocity, and precipitation intensity are investigated for convective and stratiform precipitation regimes and directly compared between MC3E and TWP-ICE cases. The result shows MC3E convection is characterized with very strong reflectivity (up to 60dBZ), slight negative differential reflectivity (-0.8 0 dB) and near-zero specific differential phase above the freezing levels. On the other hand, TWP-ICE convection shows strong reflectivity (up to 50dBZ), slight positive differential reflectivity (0 1.0 dB) and differential phase (0 0.8 dB/km). Hydrometeor IDentification (HID) algorithm from the observation and simulations detect hail-dominant convection core in MC3E, while graupel-dominant convection core in TWP-ICE. This land-ocean contrast

  17. Polarimetric studies of polyethylene terephtalate flexible substrates

    Science.gov (United States)

    Stchakovsky, M.; Garcia-Caurel, E.; Warenghem, M.

    2008-12-01

    Polymer sheets are currently used worldwide in a wide range of applications. The manufacturing process of these sheets involves extruding machines that stretch the material in both lateral and longitudinal directions with respect to the machine direction, thus inducing birefringence. In most cases, the film obtained is optically biaxial. Polarimetric spectroscopy (Ellipsometry and Mueller Matrix) combined with conoscopic observation are the methods of choice to study these properties. In this work we report an analysis of commercially available polyethylene terephtalate (PET) films used as substrate for food packaging as well as for embedded electronic devices such as solar cells or flexible displays. Initial observation of these films through polarizing microscope in conoscopic mode reveals first the trace of optical axis plane with respect to the film surface and second, whether the optical axis is acute or not. This preliminary study allows optimal sample positioning for further polarimetric studies. The measurements and modelling are done in both reflection and transmission mode on several spectroscopic polarimetric setups from UV to NIR. The models give as a main result, the dielectric tensor of the film as well as its orientation with respect to the laboratory reference frame.

  18. Polarimetric Signatures from a Crop Covered Land Surface Measured by an L-band Polarimetric Radiometer

    DEFF Research Database (Denmark)

    Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    This paper describes preliminary results from field measurements of polarimetric azimuth signatures with the EMIRAD L-band polarimetric radiometer, performed over a land test site at the Institut National de la Recherche Agronomique in Avignon, France. Scans of 180 degrees in azimuth were carried...... out in order to identify an eventual dependence of the Stokes vector on the look-direction. Results indicate a clear signature, for bare soil as well as for the crop-covered surface, and variations of more than 10 K are observed....

  19. Quantum simulation of discrete curved spacetime by the Bose-Hubbard model: From analog acoustic black hole to quantum phase transition

    Science.gov (United States)

    Bemani, F.; Roknizadeh, R.; Naderi, M. H.

    2018-01-01

    We present a theoretical scheme to simulate quantum field theory in a discrete curved spacetime based on the Bose-Hubbard model describing a Bose-Einstein condensate trapped inside an optical lattice. Using the Bose-Hubbard Hamiltonian, we first introduce a hydrodynamic presentation of the system evolution in discrete space. We then show that the phase (density) fluctuations of the trapped bosons inside an optical lattice in the superfluid (Mott insulator) state obey the Klein-Gordon equation for a massless scalar field propagating in a discrete curved spacetime. We derive the effective metrics associated with the superfluid and Mott-insulator phases and, in particular, we find that in the superfluid phase the metric exhibits a singularity which can be considered as the manifestation of an analog acoustic black hole. The proposed approach is found to provide a suitable platform for quantum simulation of various spacetime metrics through adjusting the system parameters.

  20. The Bacterial Growth Curve.

    Science.gov (United States)

    Paulton, Richard J. L.

    1991-01-01

    A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)

  1. Polarimetric Edge Detector Based on the Complex Wishart Distribution

    DEFF Research Database (Denmark)

    Skriver, Henning; Schou, Jesper; Nielsen, Allan Aasbjerg

    2001-01-01

    A new edge detector for polarimetric SAR data has been developed. The edge detector is based on a newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic. The new...... for the full polarimetric detector compared to single channel approaches....

  2. Masses of Negative Multinomial Distributions: Application to Polarimetric Image Processing

    Directory of Open Access Journals (Sweden)

    Philippe Bernardoff

    2013-01-01

    Full Text Available This paper derives new closed-form expressions for the masses of negative multinomial distributions. These masses can be maximized to determine the maximum likelihood estimator of its unknown parameters. An application to polarimetric image processing is investigated. We study the maximum likelihood estimators of the polarization degree of polarimetric images using different combinations of images.

  3. Target detection with polarimetric C-band SAR

    NARCIS (Netherlands)

    Broek, A.C. van den; Dekker, R.J.; Smith, A.J.E.; Vries, F.P.P. de

    1999-01-01

    We have studied an optimal target detection procedure for polarimetric SAR data by using PHARUS data collected during the MIMEX campaign. The detection method is especially suitable when no a priory knowledge of the target is available. We have found that polarimetric whitening filtering preceding

  4. Polarimetric Radar Retrievals in Southeast Texas During Hurricane Harvey

    Science.gov (United States)

    Wolff, D. B.; Petersen, W. A.; Tokay, A.; Marks, D. A.; Pippitt, J. L.; Kirstetter, P. E.

    2017-12-01

    Hurricane Harvey hit the Texas Gulf Coast as a major hurricane on August 25, 2017 before exiting the state as a tropical storm on September 1, 2017. In its wake, it left a flood of historic proportions, with some areas measuring 60 inches of rain over a five-day period. Although the storm center stayed west of the immediate Houston area training bands of precipitation impacted the Houston area for five full days. The National Weather Service (NWS) WSR88D dual-polarimetric radar (KHGX), located southeast of Houston, maintained operations for the entirety of the event. The Harris County Flood Warning System (HCFWS) had 150 rain gauges deployed in its network and seven NWS Automated Surface Observing Systems (ASOS) rain gauges are also located in the area. In this study, we used the full radar data set to retrieve daily and event-total precipitation estimates within 120 km of the KHGX radar for the period August 25-29, 2017. These estimates were then compared to the HCFWS and ASOS gauges. Three different polarimetric hybrid rainfall retrievals were used: Ciffeli et al. 2011; Bringi et al. 2004; and, Chen et al. 2017. Each of these hybrid retrievals have demonstrated robust performance in the past. However, both daily and event-total comparisons from each of these retrievals compared to those of HCFWS and ASOS rain gauge networks resulted in significant underestimates by the radar retrievals. These radar underestimates are concerning. Sources of error and variance will be investigated to understand the source of radar-gauge disagreement. One current hypothesis is that due to the large number of small drops often found in hurricanes, the differential reflectivity and specific differential phase are relatively small so that the hybrid algorithms use only the reflectivity/rain rate procedure (so called Z-R relationships), and hence rarely invoke the ZDR or KDP procedures. Thus, an alternative Z-R relationship must be invoked to retrieve accurate rain rate estimates.

  5. Phase transformations by dilatometry: TTT curve of high chromium white cast iron; Transformacoes de fase por dilatometria: curva TTT do ferro fundido branco de alto cromo

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, A.I. [UNESP, Rio Claro, SP (Brazil). Dept. de Fisica; Almeida Rollo, J.M.D. de; Di Lorenzo, P.L. [Sao Paulo Univ., SP (Brazil). Escola Politecnica

    1995-12-31

    The TTT curve of high chromium white cast iron is obtained using high speed quenching dilatometer. Generally, this grade of cast iron is used in abrasive wear resistance component. Thirteen thermal cycles was performed to obtain this curve. The samples were heated up to 1000 deg C whit 15 minutes soaking for homogeneous austenization, and cooling to isothermal temperature. Time transformation was determined for each sample. Metallographic analysis and Vickers hardness measurement were performed to confirm the phase transformation products. Finally, the TTT curve was applied to high chromium white cast iron, with material annealing and quenching performed from 1000 deg C and 60 minutes soaking time in a resistive furnace 8 refs., 4 figs., 1 tab.

  6. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walt; Krajewski, Witek; Wolff, David; Gatlin, Patrick

    2015-04-01

    to efforts using the NPOL radar dataset. The initial portions of the "process" involved dual-polarimetric quality control procedures which employed standard phase and correlation-based approaches to removal of clutter and non-meteorological echo. Calculation of a scale-adaptive KDP was accomplished using the method of Wang and Chandrasekar (2009; J. Atmos. Oceanic Tech.). A dual-polarimetric blockage algorithm based on Lang et al. (2009; J. Atmos. Oceanic Tech.) was then implemented to correct radar reflectivity and differential reflectivity at low elevation angles. Next, hydrometeor identification algorithms were run to identify liquid and ice hydrometeors. After the quality control and data preparation steps were completed several different dual-polarimetric rain estimation algorithms were employed to estimate rainfall rates using rainfall scans collected approximately every two to three minutes throughout the campaign. These algorithms included a polarimetrically-tuned Z-R algorithm that adjusts for drop oscillations (via Bringi et al., 2004, J. Atmos. Oceanic Tech.), and several different hybrid polarimetric variable approaches, including one that made use of parameters tuned to IFloodS 2D Video Disdrometer measurements. Finally, a hybrid scan algorithm was designed to merge the rain rate estimates from multiple low level elevation angle scans (where blockages could not be appropriately corrected) in order to create individual low-level rain maps. Individual rain maps at each time step were subsequently accumulated over multiple time scales for comparison to gauge network data. The comparison results and overall error character depended strongly on rain event type, polarimetric estimator applied, and range from the radar. We will present the outcome of these comparisons and their impact on constructing composited "reference" rainfall maps at select time and space scales.

  7. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walter; Wolff, David; Krajewski, Witek; Gatlin, Patrick

    2015-01-01

    to efforts using the NPOL radar dataset. The initial portions of the "process" involved dual-polarimetric quality control procedures which employed standard phase and correlation-based approaches to removal of clutter and non-meteorological echo. Calculation of a scale-adaptive KDP was accomplished using the method of Wang and Chandrasekar (2009; J. Atmos. Oceanic Tech.). A dual-polarimetric blockage algorithm based on Lang et al. (2009; J. Atmos. Oceanic Tech.) was then implemented to correct radar reflectivity and differential reflectivity at low elevation angles. Next, hydrometeor identification algorithms were run to identify liquid and ice hydrometeors. After the quality control and data preparation steps were completed several different dual-polarimetric rain estimation algorithms were employed to estimate rainfall rates using rainfall scans collected approximately every two to three minutes throughout the campaign. These algorithms included a polarimetrically-tuned Z-R algorithm that adjusts for drop oscillations (via Bringi et al., 2004, J. Atmos. Oceanic Tech.), and several different hybrid polarimetric variable approaches, including one that made use of parameters tuned to IFloodS 2D Video Disdrometer measurements. Finally, a hybrid scan algorithm was designed to merge the rain rate estimates from multiple low level elevation angle scans (where blockages could not be appropriately corrected) in order to create individual low-level rain maps. Individual rain maps at each time step were subsequently accumulated over multiple time scales for comparison to gauge network data. The comparison results and overall error character depended strongly on rain event type, polarimetric estimator applied, and range from the radar. We will present the outcome of these comparisons and their impact on constructing composited "reference" rainfall maps at select time and space scales.

  8. Agricultural Monitoring in Northeastern Ontario, Canada, Using Multi-Temporal Polarimetric RADARSAT-2 Data

    Directory of Open Access Journals (Sweden)

    Jeffrey W. Cable

    2014-03-01

    Full Text Available The purpose of this research is to analyze how changes in acquisition time and incidence angle affect various C-band synthetic aperture radar (SAR polarimetric intensities, co-polarized phase information, polarimetric response plots and decomposition parameters for various crops typical of Northern Ontario, Canada. We examine how these parameters may be used to monitor the growth stages of five common cash crops, namely, barley (Hordeum vulgare, canola (Brassica napus, oat (Avena sativa, soybean (Glycine max and wheat (Triticum spp.. In total, nine RADARSAT-2 polarimetric images were analyzed across a 14-week period beginning in June and ending in September 2011 using two incidence angles of approximately 26° and 41°. As expected, the backscatter intensities for all targets were found to show a higher response when acquired at the steeper incidence angle (26°. All cash crop targets showed a rise and fall in backscatter response over the course of the growing season, coinciding with changing growth stages. Slight phase differences were observed for cereal crops, possibly due to one of the polarizations penetrating between the rows allowing double-bounce to occur. The polarimetric response plots and decompositions offered insight into the scattering mechanisms of each crop type, generally showing an increase in volume scattering as the crops reached maturity. Specifically, the contributions of the crops increased towards the volume scattering component and zones 4 and 2, as the crops matured in regards to the Freeman-Durden and Cloude-Pottier decompositions respectively. Overall, soybean and canola showed a more similar response in comparison to the cereal cash crops. Although the study focused on Northern Ontario, it is anticipated that these results would be relevant in investigations of multi-temporal RADARSAT-2 for agricultural zones with similar crop types.

  9. Plateaus on hardness curves of annealed hypoeutectoid steels at ~0.5 % C as a consequence of the presence оf ~Fe42C interim phase

    Directory of Open Access Journals (Sweden)

    К. Ю. Шазназаров

    2016-11-01

    Full Text Available The article presents numerous experimental data of different researchers depending on the hardness of annealed steels hypoeutectoid on the percentage of carbon content. In addition to the classical Brinell hardness measurement, data  of Jagar hardness, Shore, the width of lines on sclerometry Martens, weight loss during grinding on sandpaper are   given. Selecting tendentiously experimental data we demonstrate the plateaus on the curves of hardness of annealed hypoeutectoid steels vs. % of C at ~0.5 % С. Similar plateaus were discovered by N.S.Kournakov in the curves of properties around FeAl3, Pb3Na, Cu3Zn, which enables one to follow the analogy and declare a ~ Fe42C phase in the Fe-C system. The anomalies of properties observed in the presence of interim phase at ~ 0.5% С are definitely established (such as magnetic susceptibility, electric resistance, density, ductility, etc. for melts and austenite. Their derivative is a ferrite-cementite mixture, which – due to the experimentally established metallurgic heritage – may inherit the anomalies of properties of its parent phase. For the three states described (melt, austenite, mixed phase the anomalies of properties at ~ 0.5 % С should be denoted in some compact way, ascribing them, for example the formula of interim phase of ~ Fe42C. The assumed ~ Fe42С phase has a specific analog in the In-Zn system consisting of eutectic mixture of pure In and Zn, which form an InZn8  phase with their crystal phase, found, similar to ~Fe42С phase under the liquidus bend.

  10. Polarimetric scattering and SAR information retrieval

    CERN Document Server

    Jin, Ya-Qiu

    2013-01-01

    Taking an innovative look at Synthetic Aperture Radar (SAR), this practical reference fully covers new developments in SAR and its various methodologies and enables readers to interpret SAR imagery An essential reference on polarimetric Synthetic Aperture Radar (SAR), this book uses scattering theory and radiative transfer theory as a basis for its treatment of topics. It is organized to include theoretical scattering models and SAR data analysis techniques, and presents cutting-edge research on theoretical modelling of terrain surface. The book includes quantitative app

  11. 3.6 AND 4.5 μm PHASE CURVES OF THE HIGHLY IRRADIATED ECCENTRIC HOT JUPITER WASP-14b

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Ian; Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Lewis, Nikole K. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Kataria, Tiffany [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fortney, Jonathan J.; Laughlin, Gregory [Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95604 (United States); Schwartz, Joel [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Cowan, Nicolas B. [Department of Physics and Astronomy, Amherst College, Amherst, MA 01002 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Désert, Jean-Michel [Department of Astrophysical and Planetary Science, University of Colorado, Boulder, CO 80309 (United States); Fulton, Benjamin J.; Howard, Andrew W. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Todorov, Kamen, E-mail: iwong@caltech.edu [Institute for Astronomy, ETH Zürich, 8093 Zürich (Switzerland)

    2015-10-01

    We present full-orbit phase curve observations of the eccentric (e ∼ 0.08) transiting hot Jupiter WASP-14b obtained in the 3.6 and 4.5 μm bands using the Spitzer Space Telescope. We use two different methods for removing the intrapixel sensitivity effect and compare their efficacy in decoupling the instrumental noise. Our measured secondary eclipse depths of 0.1882% ± 0.0048% and 0.2247% ± 0.0086% at 3.6 and 4.5 μm, respectively, are both consistent with a blackbody temperature of 2402 ± 35 K. We place a 2σ upper limit on the nightside flux at 3.6 μm and find it to be 9% ± 1% of the dayside flux, corresponding to a brightness temperature of 1079 K. At 4.5 μm, the minimum planet flux is 30% ± 5% of the maximum flux, corresponding to a brightness temperature of 1380 ± 65 K. We compare our measured phase curves to the predictions of one-dimensional radiative transfer and three-dimensional general circulation models. We find that WASP-14b’s measured dayside emission is consistent with a model atmosphere with equilibrium chemistry and a moderate temperature inversion. These same models tend to overpredict the nightside emission at 3.6 μm, while underpredicting the nightside emission at 4.5 μm. We propose that this discrepancy might be explained by an enhanced global C/O ratio. In addition, we find that the phase curves of WASP-14b (7.8 M{sub Jup}) are consistent with a much lower albedo than those of other Jovian mass planets with thermal phase curve measurements, suggesting that it may be emitting detectable heat from the deep atmosphere or interior processes.

  12. Does phase 2 of the expiratory PCO2 versus volume curve have diagnostic value in emphysema patients?

    NARCIS (Netherlands)

    A.H. Kars (Alice); G. Goorden; Th. Stijnen (Theo); J.M. Bogaard (Jan); A.F.M. Verbraak (Anton); C. Hilvering

    1995-01-01

    textabstractIt has been postulated that serial inhomogeneity of ventilation in the peripheral airways in emphysema is represented by the shape of expiratory carbon dioxide tension versus volume curve. We examined the diagnostic value of this test in patients with various degrees of emphysema. The

  13. Does phase 2 of the expiratory PCO2 versus volume curve have diagnostic value in emphysema patients?

    NARCIS (Netherlands)

    A.H. Kars (Alice); G. Goorden; Th. Stijnen (Theo); J.M. Bogaard (Jan); A.F.M. Verbraak (Anton); C. Hilvering

    1995-01-01

    textabstractIt has been postulated that serial inhomogeneity of ventilation in the peripheral airways in emphysema is represented by the shape of expiratory carbon dioxide tension versus volume curve. We examined the diagnostic value of this test in patients with various degrees of

  14. Characterization and performance of a LWIR polarimetric imager

    Science.gov (United States)

    Eriksson, Johan; Bergström, David; Renhorn, Ingmar

    2017-10-01

    Polarimetric information has been shown to provide means for potentially enhancing the capacity of electro-optical sensors in areas such as target detection, recognition and identification. The potential benefit must be weighed against the added complexity of the sensor and the occurrence and robustness of polarimetric signatures. While progress in the design of novel systems for snapshot polarimetry may result in compact and lightweight polarimetric sensors, the aim of this work is to report on the design, characterization and performance of a polarimetric imager, primarily designed for polarimetric signature assessment of static scenes in the long wave thermal infrared. The system utilizes the division-of-time principle and is based on an uncooled microbolometer camera and a rotating polarizing filter. Methods for radiometric and polarimetric calibrations are discussed. A significant intrinsic polarization dependency of the microbolometer camera is demonstrated and it is shown that the ability to characterize, model and compensate for various instrument effects play a crucial role for polarimetric signature assessment.

  15. Feature-Based Nonlocal Polarimetric SAR Filtering

    Directory of Open Access Journals (Sweden)

    Xiaoli Xing

    2017-10-01

    Full Text Available Polarimetric synthetic aperture radar (PolSAR images are inherently contaminated by multiplicative speckle noise, which complicates the image interpretation and image analyses. To reduce the speckle effect, several adaptive speckle filters have been developed based on the weighted average of the similarity measures commonly depending on the model or probability distribution, which are often affected by the distribution parameters and modeling texture components. In this paper, a novel filtering method introduces the coefficient of variance ( CV and Pauli basis (PB to measure the similarity, and the two features are combined with the framework of the nonlocal mean filtering. The CV is used to describe the complexity of various scenes and distinguish the scene heterogeneity; moreover, the Pauli basis is able to express the polarimetric information in PolSAR image processing. This proposed filtering combines the CV and Pauli basis to improve the estimation accuracy of the similarity weights. Then, the similarity of the features is deduced according to the test statistic. Subsequently, the filtering is proceeded by using the nonlocal weighted estimation. The performance of the proposed filter is tested with the simulated images and real PolSAR images, which are acquired by AIRSAR system and ESAR system. The qualitative and quantitative experiments indicate the validity of the proposed method by comparing with the widely-used despeckling methods.

  16. Evaluation of the Wishart test statistics for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2003-01-01

    A test statistic for equality of two covariance matrices following the complex Wishart distribution has previously been used in new algorithms for change detection, edge detection and segmentation in polarimetric SAR images. Previously, the results for change detection and edge detection have been...... quantitatively evaluated. This paper deals with the evaluation of segmentation. A segmentation performance measure originally developed for single-channel SAR images has been extended to polarimetric SAR images, and used to evaluate segmentation for a merge-using-moment algorithm for polarimetric SAR data....

  17. Classification and Monitoring of Reed Belts Using Dual-Polarimetric TerraSAR-X Time Series

    Directory of Open Access Journals (Sweden)

    Iris Heine

    2016-06-01

    Full Text Available Synthetic aperture radar polarimetry (PolSAR and polarimetric decomposition techniques have proven to be useful tools for wetland mapping. In this study we classify reed belts and monitor their phenological changes at a natural lake in northeastern Germany using dual-co-polarized (HH, VV TerraSAR-X time series. The time series comprises 19 images, acquired between August 2014 and May 2015, in ascending and descending orbit. We calculated different polarimetric indices using the HH and VV intensities, the dual-polarimetric coherency matrix including dominant and mean alpha scattering angles, and entropy and anisotropy (normalized eigenvalue difference as well as combinations of entropy and anisotropy for the analysis of the scattering scenarios. The image classifications were performed with the random forest classifier and validated with high-resolution digital orthophotos. The time series analysis of the reed belts revealed significant seasonal changes for the double-bounce–sensitive parameters (intensity ratio HH/VV and intensity difference HH-VV, the co-polarimetric coherence phase and the dominant and mean alpha scattering angles and in the dual-polarimetric coherence (amplitude, anisotropy, entropy, and anisotropy-entropy combinations; whereas in summer dense leaves cause volume scattering, in winter, after leaves have fallen, the reed stems cause predominately double-bounce scattering. Our study showed that the five most important parameters for the classification of reed are the intensity difference HH-VV, the mean alpha scattering angle, intensity ratio HH/VV, and the coherence (phase. Due to the better separation of reed and other vegetation (deciduous forest, coniferous forest, meadow, winter acquisitions are preferred for the mapping of reed. Multi-temporal stacks of winter images performed better than summer ones. The combination of ascending and descending images also improved the result as it reduces the influence of the sensor

  18. C- and L-band multi-temporal polarimetric signatures of crops

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Flemming; Thomsen, Anton

    1996-01-01

    Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric SAR (EMISAR) during a number of missions at the Danish test site Foulum during 1994 and 1995. EMISAR has operated in a fully polarimetric mode at C-band since the fall of 1993 and at L-band since the beginn......Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric SAR (EMISAR) during a number of missions at the Danish test site Foulum during 1994 and 1995. EMISAR has operated in a fully polarimetric mode at C-band since the fall of 1993 and at L-band since...... the beginning of 1995. The SAR system is installed on a Danish Air Force Gulfstream aircraft, and a significant amount of polarimetric SAR data have been acquired on various missions. Polarimetric parameters for a number of different agricultural crops are shown, and the advantage of having polarimetric, multi...

  19. Nonlinear Polarimetric Microscopy for Biomedical Imaging

    Science.gov (United States)

    Samim, Masood

    A framework for the nonlinear optical polarimetry and polarimetric microscopy is developed. Mathematical equations are derived in terms of linear and nonlinear Stokes Mueller formalism, which comprehensively characterize the polarization properties of the incoming and outgoing radiations, and provide structural information about the organization of the investigated materials. The algebraic formalism developed in this thesis simplifies many predictions for a nonlinear polarimetry study and provides an intuitive understanding of various polarization properties for radiations and the intervening medium. For polarimetric microscopy experiments, a custom fast-scanning differential polarization microscope is developed, which is also capable of real-time three-dimensional imaging. The setup is equipped with a pair of high-speed resonant and galvanometric scanning mirrors, and supplemented by advanced adaptive optics and data acquisition modules. The scanning mirrors when combined with the adaptive optics deformable mirror enable fast 3D imaging. Deformable membrane mirrors and genetic algorithm optimization routines are employed to improve the imaging conditions including correcting the optical aberrations, maximizing signal intensities, and minimizing point-spread-functions of the focal volume. A field-programmable-gate array (FPGA) chip is exploited to rapidly acquire and process the multidimensional data. Using the nonlinear optical polarimetry framework and the home-built polarization microscope, a few biologically important tissues are measured and analyzed to gain insight as to their structure and dynamics. The structure and distribution of muscle sarcomere myosins, connective tissue collagen, carbohydrate-rich starch, and fruit fly eye retinal molecules are characterized with revealing polarization studies. In each case, using the theoretical framework, polarization sensitive data are analyzed to decipher the molecular orientations and nonlinear optical

  20. A new optimization procedure for the accurate characterization of thermal phase transformation curves based on controlled quenching experiments

    Directory of Open Access Journals (Sweden)

    Peterli Maurice

    2016-01-01

    Full Text Available Precise hardness and phase content prediction for quenched steel with the finite element method requires optimal material data, which is usually obtained from measured continuous cooling transformation (CCT diagrams. However, most software packages that are able to predict final phase composition require time temperature transformation (TTT diagrams. TTT diagrams can be calculated from the chemical composition of the material. With this methods the numerical prediction often result in deviations to reality. A newly developed optimization method can improve the accuracy of phase content and hardness prediction after quenching by optimizing the TTT diagram with measured data of controlled quenching experiments.

  1. CLPX-Airborne: Polarimetric Ku-Band Scatterometer (POLSCAT) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Ku-band polarimetric scatterometer (POLSCAT) data collected as part of the Cold Land Processes Field Experiment (CLPX) to enable the...

  2. Change detection in polarimetric SAR data over several time points

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Skriver, Henning

    2014-01-01

    A test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution is introduced. The test statistic is applied successfully to detect change in C-band EMISAR polarimetric SAR data over four time points....

  3. NAMMA NASA POLARIMETRIC DOPPLER WEATHER RADAR (NPOL) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Polarimetric Radar (NPOL), developed by a research team from Wallops Flight Facility, is a fully transportable and self-contained S-band research radar that...

  4. CLPX-Airborne: Multiband Polarimetric Scanning Radiometer (PSR) Imagery

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides multiband polarimetric brightness temperature images over three 25 x 25 km Meso-cell Study Areas (MSAs) in Northern Colorado. The purpose of...

  5. NAMMA NASA POLARIMETRIC DOPPLER WEATHER RADAR (NPOL) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA NASA Polarimetric Doppler Weather Radar (NPOL) dataset used the NPOL, developed by a research team from Wallops Flight Facility, is a fully transportable...

  6. Digital Beamforming Synthetic Aperture Radar (DBSAR) Polarimetric Upgrade

    Science.gov (United States)

    Rincon, Rafael F.; Perrine, Martin; McLinden, Matthew; Valett, Susan

    2011-01-01

    The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art radar system developed at NASA/Goddard Space Flight Center for the development and implementation of digital beamforming radar techniques. DBSAR was recently upgraded to polarimetric operation in order to enhance its capability as a science instrument. Two polarimetric approaches were carried out which will be demonstrated in upcoming flight campaigns.

  7. Pulse-based internal calibration of polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Skou, Niels; Christensen, Erik Lintz

    1994-01-01

    Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops and devel......Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops...

  8. Forest biomass estimation from polarimetric SAR interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Mette, T.

    2007-07-01

    Polarimetric SAR interferometry (Pol-InSAR) is a radar remote sensing technique that allows extracting forest heights by means of model-based inversions. Forest biomass is closely related to forest height, and can be derived from it with allometric relations. This work investigates the combination of the two methods to estimate forest biomass from Pol-InSAR. It develops a concept for the use of height-biomass allometry, and outlines the Pol-InSAR height inversion. The methodology is validated against a set of forest inventory data and Pol-InSAR data at L-band of the test site Traunstein. The results allow drawing conclusions on the potential of Pol-InSAR forest biomass missions. (orig.)

  9. Polarimetric ISAR: Simulation and image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, David H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-21

    In polarimetric ISAR the illumination platform, typically airborne, carries a pair of antennas that are directed toward a fixed point on the surface as the platform moves. During platform motion, the antennas maintain their gaze on the point, creating an effective aperture for imaging any targets near that point. The interaction between the transmitted fields and targets (e.g. ships) is complicated since the targets are typically many wavelengths in size. Calculation of the field scattered from the target typically requires solving Maxwell’s equations on a large three-dimensional numerical grid. This is prohibitive to use in any real-world imaging algorithm, so the scattering process is typically simplified by assuming the target consists of a cloud of independent, non-interacting, scattering points (centers). Imaging algorithms based on this scattering model perform well in many applications. Since polarimetric radar is not very common, the scattering model is often derived for a scalar field (single polarization) where the individual scatterers are assumed to be small spheres. However, when polarization is important, we must generalize the model to explicitly account for the vector nature of the electromagnetic fields and its interaction with objects. In this note, we present a scattering model that explicitly includes the vector nature of the fields but retains the assumption that the individual scatterers are small. The response of the scatterers is described by electric and magnetic dipole moments induced by the incident fields. We show that the received voltages in the antennas are linearly related to the transmitting currents through a scattering impedance matrix that depends on the overall geometry of the problem and the nature of the scatterers.

  10. Moving towards more intuitive display strategies for polarimetric image data

    Science.gov (United States)

    Ratliff, Bradley M.; Tyo, J. Scott

    2017-09-01

    The display of polarimetric imaging data has been a subject of considerable debate. Display strategies range from direct display of the Stokes vector images (or their derivatives) to false color representations. In many cases, direct interpretation of polarimetric image data using traditional display strategies is not intuitive and can at times result in confusion as to what benefit polarimetric information is actually providing. Here we investigate approaches that attempt to augment the s0 image with polarimetric information, rather than directly display it, as a means of enhancing the baseband s0 image. The benefit is that the polarization-enhanced visible or infrared image maintains a familiar look without the need for complex interpretation of the meaning of the polarimetric data, thus keeping the incorporation of polarimetric information transparent to the end user. The method can be applied to monochromatic or multi-band data, which allows color to be used for representing spectral data in multi- or hyper-spectropolarimetric applications. We take a more subjective approach to image enhancement than current techniques employ by simply seeking to improve contrast and shape information for polarized objects within a scene. We find that such approaches provide clear enhancement to the imagery when polarized objects are contained within the scene without the need for complex interpretation of polarization phenomenology.

  11. Atmospheric and precipitation sounding with polarimetric radio-occultations aboard PAZ LEO

    Science.gov (United States)

    Padulles, Ramon; Cardellach, Estel; Tomás, Sergio; Oliveras, Santi; Rius, Antonio; de la Torre, Manuel; Turk, Joseph; Ao, Chi; Kursinski, Robert; Shreiner, Bill; Ector, Dave; Cucurull, Lidia; Wickert, Jens

    2015-04-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) Radio-Occultation (RO) payload on board of the Spanish Earth Observation satellite PAZ. This will be a new technique that has never been tested before, that aims to improve the knowledge of the precipitation through simultaneous thermodynamic and vertical rain profiles. The concept is similar to that used in some polarimetric weather radars: to measure the differential phase shift between the two polarimetric antennas, although here we will use the forward scattering geometry instead of the backscattering.The depolarization effect increases as the propagation line aligns with the plane of the drops' flattening (nominally perpendicular to the local gravity, i.e., parallel to the local horizon). The RO signals cross the lower troposphere tangentially, i.e., along the local horizon, which should maximize the depolarization effect. The satellite launch is scheduled for March 2015, and it will be followed by a 6-month commissioning phase period and has an expected life of 7 years, with a goal of 10 years. A sensitivity analysis have been performed, showing that we should be able to detect the 90% of all the events with along-ray averaged rain rate higher than 5 mm/h. Also, a ground field campaign has been conducted prior to the launch of the satellite. Results from the campaign also show a good correlation between phase shifts increases and heavy rain events. We will present here the status of the mission, which will have been launched few weeks before the EGU, together with some preliminary data analysis from both the actual satellite data and the prior-to-launch work.

  12. Polarimetric rainfall retrieval from a C-Band weather radar in a tropical environment (The Philippines)

    Science.gov (United States)

    Crisologo, I.; Vulpiani, G.; Abon, C. C.; David, C. P. C.; Bronstert, A.; Heistermann, Maik

    2014-11-01

    We evaluated the potential of polarimetric rainfall retrieval methods for the Tagaytay C-Band weather radar in the Philippines. For this purpose, we combined a method for fuzzy echo classification, an approach to extract and reconstruct the differential propagation phase, Φ DP , and a polarimetric self-consistency approach to calibrate horizontal and differential reflectivity. The reconstructed Φ DP was used to estimate path-integrated attenuation and to retrieve the specific differential phase, K DP . All related algorithms were transparently implemented in the Open Source radar processing software wradlib. Rainfall was then estimated from different variables: from re-calibrated reflectivity, from re-calibrated reflectivity that has been corrected for path-integrated attenuation, from the specific differential phase, and from a combination of reflectivity and specific differential phase. As an additional benchmark, rainfall was estimated by interpolating the rainfall observed by rain gauges. We evaluated the rainfall products for daily and hourly accumulations. For this purpose, we used observations of 16 rain gauges from a five-month period in the 2012 wet season. It turned out that the retrieval of rainfall from K DP substantially improved the rainfall estimation at both daily and hourly time scales. The measurement of reflectivity apparently was impaired by severe miscalibration while K DP was immune to such effects. Daily accumulations of rainfall retrieved from K DP showed a very low estimation bias and small random errors. Random scatter was, though, strongly present in hourly accumulations.

  13. Status of PEM-based polarimetric MSE development at KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jinseok; Chung, Jinil; Oh, Seungtae; Ko, Wonha [National Fusion Research Institute, Daejeon (Korea, Republic of); Bock, Maarten de; Ong, Henry; Lange, Guido [Eindhoven University of Technology, Eindhoven (Netherlands)

    2014-10-15

    A multi-chord PEM (photo elastic modulator)-based polarimetric motional Stark effect (MSE) system is under development for the KSTAR tokamak. The conceptual design for the front optics was optimized to preserve not only the polarization state of the input light for the MSE measurements but also the signal intensity of the existing charge exchange spectroscopy (CES) system that will share the front optics with the MSE. The optics design incorporates how to determine the number of channels and the number of fibers for each channel. A dielectric coating will be applied on the mirror to minimize the relative reflectivity and the phase shift between the two orthogonal polarization components of the incident light. Lenses with low stress-birefringence constants will be adopted to minimize non-linear and random changes in the polarization through the lenses, which is a trade-off with the rather high Faraday rotation in the lenses because the latter effect is linear and can be relatively easily calibrated out. Intensive spectrum measurements and their comparisons with the simulated spectra are done to assist the design of the bandpass filter system that will also use tilting stages to remotely control the passband. Following the system installation in 2014, the MSE measurements are expected to be performed during the 2015 KSTAR campaign.

  14. Pressure drop-flow rate curves for single-phase steam in Combustion Engineering type steam generator U-tubes during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Fynan, Douglas A.; Ahn, Kwang-Il, E-mail: kiahn@kaeri.re.kr

    2016-12-15

    Highlights: • Pressure drop-flow rate curves for superheated steam in U-tubes were generated. • Forward flow of hot steam is favored in the longer and taller U-tubes. • Reverse flow of cold steam is favored in short U-tubes. • Steam generator U-tube bundle geometry and tube diameter are important. • Need for correlation development for natural convention heat transfer coefficient. - Abstract: Characteristic pressure drop-flow rate curves are generated for all row numbers of the OPR1000 steam generators (SGs), representative of Combustion Engineering (CE) type SGs featuring square bend U-tubes. The pressure drop-flow rate curves are applicable to severe accident natural circulations of single-phase superheated steam during high pressure station blackout sequences with failed auxiliary feedwater and dry secondary side which are closely related to the thermally induced steam generator tube rupture event. The pressure drop-flow rate curves which determine the recirculation rate through the SG tubes are dependent on the tube bundle geometry and hydraulic diameter of the tubes. The larger CE type SGs have greater variation of tube length and height as a function of row number with forward flow of steam favored in the longer and taller high row number tubes and reverse flow favored in the short low row number tubes. Friction loss, natural convection heat transfer coefficients, and temperature differentials from the primary to secondary side are dominant parameters affecting the recirculation rate. The need for correlation development for natural convection heat transfer coefficients for external flow over tube bundles currently not modeled in system codes is discussed.

  15. Calibration of a T-History calorimeter to measure enthalpy curves of phase change materials in the temperature range from 40 to 200 °C

    International Nuclear Information System (INIS)

    Rathgeber, Christoph; Schmit, Henri; Hennemann, Peter; Hiebler, Stefan

    2014-01-01

    Thermal energy storage using phase change materials (PCMs) provides high storage capacities in small temperature ranges. For the design of efficient latent heat storage, the enthalpy curve of a PCM has to be measured with high precision. Measurements are most commonly performed with differential scanning calorimetry (DSC). The T-History method, however, proved to be favourable for the characterization of typical PCMs due to large samples and a measuring procedure close to conditions found in applications. As T-History calorimeters are usually individual constructions, performing a careful calibration procedure is decisive to ensure optimal measuring accuracy. We report in this paper on the calibration of a T-History calorimeter with a working range from 40 to 200 °C that was designed and built at our institute. A three-part procedure, consisting of an indium calibration, a measurement of the specific heat of copper and measurements of three solid–liquid PCMs (stearic acid, dimethyl terephthalate and d-mannitol), was performed and an advanced procedure for the correction of enthalpy curves was developed. When comparing T-History enthalpy curves to literature data and DSC step measurements, good agreement within the uncertainty limits demanded by RAL testing specifications was obtained. Thus, our design of a T-History calorimeter together with the developed calibration procedure provides the measuring accuracy that is required to identify the most suitable PCM for a given application. In addition, the dependence of the enthalpy curve on the sample size can be analysed by comparing results obtained with T-History and DSC and the behaviour of the bulk material in real applications can be predicted. (paper)

  16. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 Mobile X-Band Polarimetric Weather Radar dataset was collected by the Mobile X-band Polarimetric Weather Radar on Wheels (X-POW), which is a Doppler...

  17. Multi-Temporal Polarimetric RADARSAT-2 for Land Cover Monitoring in Northeastern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Jeffrey W. Cable

    2014-03-01

    Full Text Available For successful applications of microwave remote sensing endeavors it is essential to understand how surface targets respond to changing synthetic aperture radar (SAR parameters. The purpose of the study is to examine how two particular parameters, acquisition time and incidence angle, influences the response from various land use/land cover types (forests, urban infrastructure, surface water and marsh wetland targets using nine RADARSAT-2 C-band fine-beam (FQ7 and FQ21 fully polarimetric SAR data acquired during the 2011 growing season over northern Ontario, Canada. The results indicate that backscatter from steep incidence angle acquisitions was typically higher than shallow angles. Wetlands showed an increase in HH and HV intensity due to the growth of emergent vegetation over the course of the summer. The forest and urban targets displayed little variation in backscatter over time. The surface water target showed the greatest difference with respect to incidence angle, but was also determined to be the most affected by wind conditions. Analysis of the co-polarized phase difference revealed the urban target as greatly influenced by the incidence angle. The observed phase differences of the wetland target for all acquisitions also suggested evidence of double-bounce interactions, while the forest and surface water targets showed little to no phase difference. In addition, Cloude-Pottier and Freeman-Durden decompositions, when analyzed in conjunction with polarimetric response plots, provided supporting information to confidently identify the various targets and their scattering mechanisms.

  18. Microphysical properties of frozen particles inferred from Global Precipitation Measurement (GPM) Microwave Imager (GMI) polarimetric measurements

    Science.gov (United States)

    Gong, Jie; Wu, Dong L.

    2017-02-01

    Scattering differences induced by frozen particle microphysical properties are investigated, using the vertically (V) and horizontally (H) polarized radiances from the Global Precipitation Measurement (GPM) Microwave Imager (GMI) 89 and 166 GHz channels. It is the first study on frozen particle microphysical properties on a global scale that uses the dual-frequency microwave polarimetric signals.From the ice cloud scenes identified by the 183.3 ± 3 GHz channel brightness temperature (Tb), we find that the scattering by frozen particles is highly polarized, with V-H polarimetric differences (PDs) being positive throughout the tropics and the winter hemisphere mid-latitude jet regions, including PDs from the GMI 89 and 166 GHz TBs, as well as the PD at 640 GHz from the ER-2 Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) during the TC4 campaign. Large polarization dominantly occurs mostly near convective outflow regions (i.e., anvils or stratiform precipitation), while the polarization signal is small inside deep convective cores as well as at the remote cirrus region. Neglecting the polarimetric signal would easily result in as large as 30 % error in ice water path retrievals. There is a universal bell curve in the PD-TBV relationship, where the PD amplitude peaks at ˜ 10 K for all three channels in the tropics and increases slightly with latitude (2-4 K). Moreover, the 166 GHz PD tends to increase in the case where a melting layer is beneath the frozen particles aloft in the atmosphere, while 89 GHz PD is less sensitive than 166 GHz to the melting layer. This property creates a unique PD feature for the identification of the melting layer and stratiform rain with passive sensors.Horizontally oriented non-spherical frozen particles are thought to produce the observed PD because of different ice scattering properties in the V and H polarizations. On the other hand, turbulent mixing within deep convective cores inevitably promotes the random

  19. Polarimetric C-Band SAR Observations of Sea Ice in the Greenland Sea

    DEFF Research Database (Denmark)

    Thomsen, Bjørn Bavnehøj; Nghiem, S.V.; Kwok, R.

    1998-01-01

    The fully polarimetric EMISAR acquired C-band radar signatures of sea ice in the Greenland Sea during a campaign in March 1995. The authors present maps of polarimetric signatures over an area containing various kinds of ice and discuss the use of polarimetric SAR for identification of ice types...

  20. Observations on the polarimetric imagery collection experiment database

    Science.gov (United States)

    Woolley, Mark; Michalson, Jacob; Romano, Joao

    2011-10-01

    The Spectral and Polarimetric Imagery Collection Experiment (SPICE) is an ongoing collaborative effort that commenced in February 2010 between the US Army ARDEC and Army Research Laboratory (ARL). SPICE is focused on the collection of mid-wave and long-wave infrared imagery using hyperspectral, polarimetric, and broadband sensors. The overall objective of SPICE is to collect a comprehensive database of the different modalities spanning multiple years to capture sensor performance encompassing a wide variety of meteorological (MET) conditions, diurnal, and seasonal changes inherent to Picatinny's northern New Jersey location. Utilizing the Precision Armament Laboratory (PAL) tower at Picatinny Arsenal, the sensors are autonomously collecting the desired data around the clock at multiple ranges containing surrogate 2S3 Self-Propelled Howitzer targets positioned at different orientations in an open woodland field. This database allows for: 1) Understanding of signature variability under adverse weather conditions; 2) Development of robust algorithms; 3) Development of new sensors; 4) Evaluation of polarimetric technology; and 5) Evaluation of fusing the different sensor modalities. In this paper, we will revisit the SPICE data collection objectives and the sensors deployed. We will present, in a statistical sense, the integrity of the data in the long-wave infrared (LWIR) polarimetric database collected from February through September 2010 and issues and lessons learned associated with a fully autonomous, around the clock data collection. We will also demonstrate sample LWIR polarimetric imagery and the performance of the Stokes parameters under adverse weather conditions.

  1. Spitzer/MIPS 24 μm Observations of HD 209458b: Three Eclipses, Two and a Half Transits, and a Phase Curve Corrupted by Instrumental Sensitivity Variations

    Science.gov (United States)

    Crossfield, Ian J. M.; Knutson, Heather; Fortney, Jonathan; Showman, Adam P.; Cowan, Nicolas B.; Deming, Drake

    2012-06-01

    We report the results of an analysis of all Spitzer/MIPS 24 μm observations of HD 209458b, one of the touchstone objects in the study of irradiated giant planet atmospheres. Altogether, we analyze two and a half transits, three eclipses, and a 58 hr near-continuous observation designed to detect the planet's thermal phase curve. The results of our analysis are: (1) a mean transit depth of 1.484% ± 0.033%, consistent with previous measurements and showing no evidence of variability in transit depth at the 3% level. (2) A mean eclipse depth of 0.338% ± 0.026%, somewhat higher than that previously reported for this system; this new value brings observations into better agreement with models. From this eclipse depth we estimate an average dayside brightness temperature of 1320 ± 80 K; the dayside flux shows no evidence of variability at the 12% level. (3) Eclipses in the system occur 32 ± 129 s earlier than would be expected from a circular orbit, which constrains the orbital quantity ecos ω to be 0.00004 ± 0.00033. This result is fully consistent with a circular orbit and sets an upper limit of 140 m s-1 (3σ) on any eccentricity-induced velocity offset during transit. The phase curve observations (including one of the transits) exhibit an anomalous trend similar to the detector ramp seen in previous Spitzer/IRAC observations; by modeling this ramp we recover the system parameters for this transit. The long-duration photometry which follows the ramp and transit exhibits a gradual ~0.2% decrease in flux over ~30 hr. This effect is similar to that seen in pre-launch calibration data taken with the 24 μm array and is better fit by an instrumental model than a model invoking planetary emission. The large uncertainties associated with this poorly understood, likely instrumental effect prevent us from usefully constraining the planet's thermal phase curve. Our observations highlight the need for a thorough understanding of detector-related instrumental effects on

  2. Spitzer/MIPS 24 {mu}m OBSERVATIONS OF HD 209458b: THREE ECLIPSES, TWO AND A HALF TRANSITS, AND A PHASE CURVE CORRUPTED BY INSTRUMENTAL SENSITIVITY VARIATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Crossfield, Ian J. M. [Department of Physics, and Astronomy, University of California, Los Angeles, CA 90095 (United States); Knutson, Heather [Caltech Division of Geological and Planetary Sciences, Pasadena, CA 91125 (United States); Fortney, Jonathan [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Showman, Adam P. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Deming, Drake, E-mail: ianc@astro.ucla.edu [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

    2012-06-20

    We report the results of an analysis of all Spitzer/MIPS 24 {mu}m observations of HD 209458b, one of the touchstone objects in the study of irradiated giant planet atmospheres. Altogether, we analyze two and a half transits, three eclipses, and a 58 hr near-continuous observation designed to detect the planet's thermal phase curve. The results of our analysis are: (1) a mean transit depth of 1.484% {+-} 0.033%, consistent with previous measurements and showing no evidence of variability in transit depth at the 3% level. (2) A mean eclipse depth of 0.338% {+-} 0.026%, somewhat higher than that previously reported for this system; this new value brings observations into better agreement with models. From this eclipse depth we estimate an average dayside brightness temperature of 1320 {+-} 80 K; the dayside flux shows no evidence of variability at the 12% level. (3) Eclipses in the system occur 32 {+-} 129 s earlier than would be expected from a circular orbit, which constrains the orbital quantity ecos {omega} to be 0.00004 {+-} 0.00033. This result is fully consistent with a circular orbit and sets an upper limit of 140 m s{sup -1} (3{sigma}) on any eccentricity-induced velocity offset during transit. The phase curve observations (including one of the transits) exhibit an anomalous trend similar to the detector ramp seen in previous Spitzer/IRAC observations; by modeling this ramp we recover the system parameters for this transit. The long-duration photometry which follows the ramp and transit exhibits a gradual {approx}0.2% decrease in flux over {approx}30 hr. This effect is similar to that seen in pre-launch calibration data taken with the 24 {mu}m array and is better fit by an instrumental model than a model invoking planetary emission. The large uncertainties associated with this poorly understood, likely instrumental effect prevent us from usefully constraining the planet's thermal phase curve. Our observations highlight the need for a thorough

  3. A New Ka-Band Scanning Radar Facility: Polarimetric and Doppler Spectra Measurements of Snow Events

    Science.gov (United States)

    Oue, M.; Kollias, P.; Luke, E. P.; Mead, J.

    2017-12-01

    Polarimetric radar analyses offer the capability of identification of ice hydrometeor species as well as their spatial distributions. In addition to polarimetric parameter observations, Doppler spectra measurements offer unique insights into ice particle properties according to particle fall velocities. In particular, millimeter-wavelength radar Doppler spectra can reveal supercooled liquid cloud droplets embedded in ice precipitation clouds. A Ka-band scanning polarimetric radar, named KASPR, was installed in an observation facility at Stony Brook University, located 22 km west of the KOKX NEXRAD radar at Upton, NY. The KASPR can measure Doppler spectra and full polarimetric variables, including radar reflectivity, differential reflectivity (ZDR), differential phase (φDP), specific differential phase (KDP), correlation coefficient (ρhv), and linear depolarization ratio (LDR). The facility also includes a micro-rain radar and a microwave radiometer capable of measuring reflectivity profiles and integrated liquid water path, respectively. The instruments collected initial datasets during two snowstorm events and two snow shower events in March 2017. The radar scan strategy was a combination of PPI scans at 4 elevation angles (10, 20, 45, and 60°) and RHI scans in polarimetry mode, and zenith pointing with Doppler spectra collection. During the snowstorm events the radar observed relatively larger ZDR (1-1.5 dB) and enhanced KDP (1-2 ° km-1) at heights corresponding to a plate/dendrite crystal growth regime. The Doppler spectra showed that slower-falling particles ( 1 m s-1). The weakly increased ZDR could be produced by large, faster falling particles such as quasi-spherical aggregates, while the enhanced KDP could be produced by highly-oriented oblate, slowly-falling particles. Below 2 km altitude, measurements of dual wavelength ratio (DWR) based on Ka and S-band reflectivities from the KASPR and NEXRAD radars were available. Larger DWR (>10 dB) suggested

  4. A Novel Ship Detection Method Using Model-Based Decomposition as a Polarimetric Band-Stop Filter

    Science.gov (United States)

    Sugimoto, Mitsunobu; Marino, Armando; Ouchi, Kazuo; Nakamura, Yasuhiro

    2013-08-01

    In this study, a novel ship detection method using model-based decomposition is suggested. The model-based decomposition is one of the popular analytical methods of POLSAR (polarimetric SAR) data. Since most of the scattering on the sea is surface scattering, the model-based decomposition can be used as a band-stop filter, to block out surface scattering component. As a result, ships, which generally have more complex scattering process, can be detected. Advanced Land Observation Satellite-Phased Array L-band SAR (ALOS-PALSAR) polarimetric SAR data and available reference data for validation are used in the study. The result was processed using adaptive-CFAR (constant false alarm rate) technique and compared with the reference data.

  5. Monte Carlo simulation of dynamic phase transitions and frequency dispersions of hysteresis curves in core/shell ferrimagnetic cubic nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Vatansever, Erol, E-mail: erol.vatansever@deu.edu.tr

    2017-05-10

    By means of Monte Carlo simulation method with Metropolis algorithm, we elucidate the thermal and magnetic phase transition behaviors of a ferrimagnetic core/shell nanocubic system driven by a time dependent magnetic field. The particle core is composed of ferromagnetic spins, and it is surrounded by an antiferromagnetic shell. At the interface of the core/shell particle, we use antiferromagnetic spin–spin coupling. We simulate the nanoparticle using classical Heisenberg spins. After a detailed analysis, our Monte Carlo simulation results suggest that present system exhibits unusual and interesting magnetic behaviors. For example, at the relatively lower temperature regions, an increment in the amplitude of the external field destroys the antiferromagnetism in the shell part of the nanoparticle, leading to a ground state with ferromagnetic character. Moreover, particular attention has been dedicated to the hysteresis behaviors of the system. For the first time, we show that frequency dispersions can be categorized into three groups for a fixed temperature for finite core/shell systems, as in the case of the conventional bulk systems under the influence of an oscillating magnetic field. - Highlights: • Cubic core/shell nanoparticle is considered. • Monte-Carlo simulation with Metropolis algorithm is used. • The particle is subjected to time dependent oscillating magnetic field. • External field destroys the antiferromagnetism in the shell part of particle. • Frequency dispersions of hysteresis loop areas can be categorized into three groups.

  6. Initial assessment of an airborne Ku-band polarimetric SAR.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2013-02-01

    Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.

  7. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    depths. The validity of the scattering models is examined using L-band polarimetric interferometric SAR data acquired with the EMISAR system over an ice cap located in the percolation zone of the Greenland ice sheet. Radar reflectors were deployed on the ice surface prior to the data acquisition in order......This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...... scattering models are similar to the oriented-volume model and the random-volume-over-ground model used in vegetation studies, but the ice models are adapted to the different geometry of land ice. Also, due to compaction, land ice is not uniform; a fact that must be taken into account for large penetration...

  8. On the calibration of the polarimetric slope - albedo relation for asteroids: Work in progress

    Directory of Open Access Journals (Sweden)

    A. Cellino

    2011-09-01

    Full Text Available Asteroid polarimetry is known to be an excellent tool to derive information on the geometric albedo of these objects. This is made possible by the existence of a relation between the albedo and the morphology of the curve which describes the variation of the degree of linear polarization of asteroid light as a function of the illumination conditions. A major problem is that the calibration of the commonly accepted form of the polarization - albedo relation includes numerical coefficients which are affected by fairly high uncertainties. Following some recommendations issued by IAU Commission 15, we are trying to improve the albedo - polarization relation by taking advantage of new polarimetric data obtained in dedicated observation campaigns. We present here some very preliminary results.

  9. Compact polarimetric SAR product and calibration considerations for target analysis

    Science.gov (United States)

    Sabry, Ramin

    2016-10-01

    Compact polarimetric (CP) data exploitation is currently of growing interest considering the new generation of such Synthetic Aperture Radar (SAR) systems. These systems offer target detection and classification capabilities comparable to those of polarimetric SARs (PolSAR) with less stringent requirements. A good example is the RADARSAT Constellation Mission (RCM). In this paper, some characteristic CP products are described and effects of CP mode deviation from ideal circular polarization transmit on classifications are modeled. The latter is important for operation of typical CP modes (e.g., RCM). The developed model can be used to estimate the ellipticity variation from CP measured data, and hence, calibrate the classification products.

  10. Authentication of gold nanoparticle encoded pharmaceutical tablets using polarimetric signatures.

    Science.gov (United States)

    Carnicer, Artur; Arteaga, Oriol; Suñé-Negre, Josep M; Javidi, Bahram

    2016-10-01

    The counterfeiting of pharmaceutical products represents concerns for both industry and the safety of the general public. Falsification produces losses to companies and poses health risks for patients. In order to detect fake pharmaceutical tablets, we propose producing film-coated tablets with gold nanoparticle encoding. These coated tablets contain unique polarimetric signatures. We present experiments to show that ellipsometric optical techniques, in combination with machine learning algorithms, can be used to distinguish genuine and fake samples. To the best of our knowledge, this is the first report using gold nanoparticles encoded with optical polarimetric classifiers to prevent the counterfeiting of pharmaceutical products.

  11. Estimating the Concentration of Large Raindrops from Polarimetric Radar and Disdrometer Observations

    Science.gov (United States)

    Carey, Lawrence D.; Petersen, Walter A; Gatlink, Patrick N.

    2013-01-01

    occurrence of large rain drops (D > 5 mm) in disdrometer observations, either stand alone or networked, generally representative and consistent with polarimetric radar observations? We first show from simulations that the concentration of large (D > 5 mm) rain drops (N(sub T5)) can be estimated from polarimetric observations of specific differential phase (K(sub dp)) and differential reflectivity (Z(sub dr)), N(sub T5)=F(K(sub dp),Z(sub dr)), or horizontal reflectivity (Z(sub h)) and Z(sub dr), N(sub T5)=(Z(sub h),Z(sub dr)). We assess the error associated with polarimetric retrieval of N(sub T5), including sensitivity to D(sub max) parameterization assumptions and measurement error in the radar simulations. Polarimetric measurements at S-band and C-band will then be used to retrieve estimates of N(sub T5) and compared to disdrometer estimates of N(sub T5). After careful consideration of retrieval error, we will check consistency between disdrometer and polarimetric radar estimates of N(sub T5) and the frequency of occurrence of large rain drops in a variety of precipitating regimes using data from NASA's Global Precipitation Measurement (GPM) Ground Validation (GV) program, including field campaigns such as MC3E (Oklahoma) and IFloodS (Iowa) and extended measurements over Huntsville, Alabama and NASA Wallops Flight Facility in coastal Virginia.

  12. Identification of hydrometeor mixtures in polarimetric radar measurements and their linear de-mixing

    Science.gov (United States)

    Besic, Nikola; Ventura, Jordi Figueras i.; Grazioli, Jacopo; Gabella, Marco; Germann, Urs; Berne, Alexis

    2017-04-01

    The issue of hydrometeor mixtures affects radar sampling volumes without a clear dominant hydrometeor type. Containing a number of different hydrometeor types which significantly contribute to the polarimetric variables, these volumes are likely to occur in the vicinity of the melting layer and mainly, at large distance from a given radar. Motivated by potential benefits for both quantitative and qualitative applications of dual-pol radar, we propose a method for the identification of hydrometeor mixtures and their subsequent linear de-mixing. This method is intrinsically related to our recently proposed semi-supervised approach for hydrometeor classification. The mentioned classification approach [1] performs labeling of radar sampling volumes by using as a criterion the Euclidean distance with respect to five-dimensional centroids, depicting nine hydrometeor classes. The positions of the centroids in the space formed by four radar moments and one external parameter (phase indicator), are derived through a technique of k-medoids clustering, applied on a selected representative set of radar observations, and coupled with statistical testing which introduces the assumed microphysical properties of the different hydrometeor types. Aside from a hydrometeor type label, each radar sampling volume is characterized by an entropy estimate, indicating the uncertainty of the classification. Here, we revisit the concept of entropy presented in [1], in order to emphasize its presumed potential for the identification of hydrometeor mixtures. The calculation of entropy is based on the estimate of the probability (pi ) that the observation corresponds to the hydrometeor type i (i = 1,ṡṡṡ9) . The probability is derived from the Euclidean distance (di ) of the observation to the centroid characterizing the hydrometeor type i . The parametrization of the d → p transform is conducted in a controlled environment, using synthetic polarimetric radar datasets. It ensures balanced

  13. Using WSR-88D Polarimetric Data to Identify Bird-Contaminated Doppler Velocities

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2013-01-01

    Full Text Available As an important part of Doppler velocity data quality control for radar data assimilation and other quantitative applications, an automated technique is developed to identify and remove contaminated velocities by birds, especially migrating birds. This technique builds upon the existing hydrometeor classification algorithm (HCA for dual-polarimetric WSR-88D radars developed at the National Severe Storms Laboratory, and it performs two steps. In the first step, the fuzzy-logic method in the HCA is simplified and used to identify biological echoes (mainly from birds and insects. In the second step, another simple fuzzy logic method is developed to detect bird echoes among the biological echoes identified in the first step and thus remove bird-contaminated velocities. The membership functions used by the fuzzy logic method in the second step are extracted from normalized histograms of differential reflectivity and differential phase for birds and insects, respectively, while the normalized histograms are constructed by polarimetric data collected during the 2012 fall migrating season and sorted for bird and insects, respectively. The performance and effectiveness of the technique are demonstrated by real-data examples.

  14. Polarimetric ice sounding at P-band: First results

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2009-01-01

    For polar ice sheets valuable stress and strain information can be deduced from the crystal orientation fabric (COF) and its prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties...

  15. Investigation of Polarimetric SAR Data Acquired at Multiple Incidence Angles

    DEFF Research Database (Denmark)

    Svendsen, Morten Thougaard; Skriver, Henning; Thomsen, A.

    1998-01-01

    The dependence of different polarimetric parameters on the incidence angles in the range of 30° to 60° is investigated for a number of different crops using airborne SAR data. The purpose of the investigation is to determine the effect of the variation of incidence angle within a SAR image when...

  16. Polarimetric synthetic aperture radar data and the complex Wishart distribution

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2003-01-01

    When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart distribu...

  17. Processing of dual-orthogonal cw polarimetric radar signals

    NARCIS (Netherlands)

    Babur, G.

    2009-01-01

    The thesis consists of two parts. The first part is devoted to the theory of dual-orthogonal polarimetric radar signals with continuous waveforms. The thesis presents a comparison of the signal compression techniques, namely correlation and de-ramping methods, for the dual-orthogonal sophisticated

  18. L-Band Polarimetric Correlation Radiometer with Subharmonic Sampling

    DEFF Research Database (Denmark)

    Rotbøll, Jesper; Søbjærg, Sten Schmidl; Skou, Niels

    2001-01-01

    A novel L-band radiometer trading analog complexity for digital ditto has been designed and built. It is a fully polarimetric radiometer of the correlation type and it is based on the sub-harmonic sampling principle in which the L-band signal is directly sampled by a fast A to D converter...

  19. Ice sheet anisotropy measured with polarimetric ice sounding radar

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2010-01-01

    For polar ice sheets, valuable stress and strain information can be deduced from crystal orientation fabrics (COF) and their prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties asso...

  20. The Danish polarimetric SAR for remote sensing applications

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Madsen, Søren Nørvang; Dall, Jørgen

    1994-01-01

    Presents the Danish polarimetric SAR system, EMISAR, and the approach taken in the system design to achieve a reliable high performance system. The design and implementation of the antenna system as well as the analog and digital hardware are discussed. The SAR utilises a dual polarised microstri...

  1. A novel L-band polarimetric radiometer featuring subharmonic sampling

    DEFF Research Database (Denmark)

    Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D...

  2. Saturn's icy satellites investigated by Cassini-VIMS. I. Full-disk properties: 350-5100 nm reflectance spectra and phase curves

    Science.gov (United States)

    Filacchione, G.; Capaccioni, F.; McCord, T.B.; Coradini, A.; Cerroni, P.; Bellucci, G.; Tosi, F.; D'Aversa, E.; Formisano, V.; Brown, R.H.; Baines, K.H.; Bibring, J.-P.; Buratti, B.J.; Clark, R.N.; Combes, M.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, Christophe; Hansen, G.; Hibbitts, K.; Showalter, M.; Newman, S.

    2007-01-01

    Saturn's icy satellites are among the main scientific objectives of the Cassini-VIMS (Visual and Infrared Mapping Spectrometer) experiment. This paper contains a first systematic and comparative analysis of the full-disk spectral properties of Dione, Enceladus, Epimetheus, Hyperion, Iapetus, Mimas, Phoebe, Rhea and Tethys as observed by VIMS from July 2004 to June 2005. The disk integrated properties (350-5100 nm reflectance spectra and phase curves at 550-2232 nm) and images of satellites are reported and discussed in detail together with the observed geometry. In general, the spectra in the visible spectral range are almost featureless and can be classified according to the spectral slopes: from the bluish Enceladus and Phoebe to the redder Iapetus, Hyperion and Epimetheus. In the 1000-1300 nm range the spectra of Enceladus, Tethys, Mimas and Rhea are characterized by a negative slope, consistent with a surface largely dominated by water ice, while the spectra of Iapetus, Hyperion and Phoebe show a considerable reddening pointing out the relevant role played by darkening materials present on the surface. In between these two classes are Dione and Epimetheus, which have a flat spectrum in this range. The main absorption bands identified in the infrared are the 1520, 2020, 3000 nm H2O/OH bands (for all satellites), although Iapetus dark terrains show mostly a deep 3000 nm band while the 1520 and 2020 nm bands are very faint. In this spectral range, the Iapetus spectrum is characterized by a strong reddening. The CO2 band at 4260 nm and the Fresnel ice peak around 3100 nm are evident only on Hyperion, Phoebe and Iapetus. The phase curves at 550 and at 2232 nm are reported for all the available observations in the 0??-144?? range; Rhea shows an opposition surge at visible wavelengths in the 0.5??-1.17?? interval. The improvement on the retrieval of the full-disk reflectance spectra can be appreciated by a direct comparison with ground-based telescopic data available

  3. VLBA polarimetric monitoring of 3C 111

    Science.gov (United States)

    Beuchert, T.; Kadler, M.; Perucho, M.; Großberger, C.; Schulz, R.; Agudo, I.; Casadio, C.; Gómez, J. L.; Gurwell, M.; Homan, D.; Kovalev, Y. Y.; Lister, M. L.; Markoff, S.; Molina, S. N.; Pushkarev, A. B.; Ros, E.; Savolainen, T.; Steinbring, T.; Thum, C.; Wilms, J.

    2018-02-01

    Context. While studies of large samples of jets of active galactic nuclei (AGN) are important in order to establish a global picture, dedicated single-source studies are an invaluable tool for probing crucial processes within jets on parsec scales. These processes involve in particular the formation and geometry of the jet magnetic field as well as the flow itself. Aims: We aim to better understand the dynamics within relativistic magneto-hydrodynamical flows in the extreme environment and close vicinity of supermassive black holes. Methods: We analyze the peculiar radio galaxy 3C 111, for which long-term polarimetric observations are available. We make use of the high spatial resolution of the VLBA network and the MOJAVE monitoring program, which provides high data quality also for single sources and allows us to study jet dynamics on parsec scales in full polarization with an evenly sampled time-domain. While electric vectors can probe the underlying magnetic field, other properties of the jet such as the variable (polarized) flux density, feature size, and brightness temperature, can give valuable insights into the flow itself. We complement the VLBA data with data from the IRAM 30-m Telescope as well as the SMA. Results: We observe a complex evolution of the polarized jet. The electric vector position angles (EVPAs) of features traveling down the jet perform a large rotation of ≳180∘ across a distance of about 20 pc. As opposed to this smooth swing, the EVPAs are strongly variable within the first parsecs of the jet. We find an overall tendency towards transverse EVPAs across the jet with a local anomaly of aligned vectors in between. The polarized flux density increases rapidly at that distance and eventually saturates towards the outermost observable regions. The transverse extent of the flow suddenly decreases simultaneously to a jump in brightness temperature around where we observe the EVPAs to turn into alignment with the jet flow. Also the gradient

  4. Feasibility Study of Rain Rate Monitoring from Polarimetric GNSS Propagation Parameters

    Directory of Open Access Journals (Sweden)

    Hao An

    2016-12-01

    Full Text Available In this work, the feasibility of estimating rain rate based on polarimetric Global Navigation Satellite Systems (GNSS signals is explored in theory. After analyzing the cause of polarimetric signals, three physical-mathematical relation models between co-polar phase shift (KHH, KVV, specific differential phase shift (KDP, and rain rate (R are respectively investigated. These relation models are simulated based on four different empirical equations of nonspherical raindrops and simulated Gamma raindrop size distribution. They are also respectively analyzed based on realistic Gamma raindrop size distribution and maximum diameter of raindrops under three different rain types: stratiform rain, cumuliform rain, and mixed clouds rain. The sensitivity of phase shift with respect to some main influencing factors, such as shape of raindrops, frequency, as well as elevation angle, is also discussed, respectively. The numerical results in this study show that the results by scattering algorithms T-matrix are consistent with those from Rayleigh Scattering Approximation. It reveals that they all have the possibility to estimate rain rate using the KHH-R, KVV-R or KDP-R relation. It can also be found that the three models are all affected by shape of raindrops and frequency, while the elevation angle has no effect on KHH-R. Finally, higher frequency L1 or B1 and lower elevation angle are recommended and microscopic characteristics of raindrops, such as shape and size distribution, are deemed to be important and required for further consideration in future experiments. Since phase shift is not affected by attenuation and not biased by ground clutter cancellers, this method has considerable potential in precipitation monitoring, which provides new opportunities for atmospheric research.

  5. Characterization of Mediterranean hail-bearing storms using an operational polarimetric X-band radar

    Directory of Open Access Journals (Sweden)

    G. Vulpiani

    2015-11-01

    It is based on an iterative approach that uses a very short-length (1 km moving window, allowing proper capture of the observed high radial gradients of the differential phase. The parameterization of the attenuation correction algorithm, which uses the reconstructed differential phase shift, is derived from electromagnetic simulations based on 3 years of drop size distribution (DSD observations collected in Rome (Italy. A fuzzy logic hydrometeor classification algorithm was also adopted to support the analysis of the storm characteristics. The precipitation field amounts were reconstructed using a combined polarimetric rainfall algorithm based on reflectivity and specific differential phase. The first storm was observed on 21 February when a winter convective system that originated in the Tyrrhenian Sea, marginally hit the central-eastern coastline of Sicily, causing a flash flood in Catania. Due to an optimal location (the system is located a few kilometers from the city center, it was possible to retrieve the storm characteristics fairly well, including the amount of rainfall field at the ground. Extemporaneous signal extinction, caused by close-range hail core causing significant differential phase shift in a very short-range path, is documented. The second storm, on 21 August 2013, was a summer mesoscale convective system that originated from a Mediterranean low pressure system lasting a few hours that eventually flooded the city of Syracuse. The undergoing physical process, including the storm dynamics, is inferred by analyzing the vertical sections of the polarimetric radar measurements. The high registered amount of precipitation was fairly well reconstructed, although with a trend toward underestimation at increasing distances. Several episodes of signal extinction were clearly manifested during the mature stage of the observed supercells.

  6. Digital Conically Scanned L-Band Radar, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort seeks to develop a digitally steered polarimetric phased array L-Band radar utilizing a novel, high performance architecture leveraging recent...

  7. Digital Conically Scanned L-Band Radar, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort seeks to develop a digitally steered polarimetric phased array L-Band radar utilizing a novel, high performance architecture leveraging recent...

  8. Do We Need to Clamp the Renal Hilum Liberally during the Initial Phase of the Learning Curve of Robot-Assisted Nephron-Sparing Surgery?

    Directory of Open Access Journals (Sweden)

    Ömer Acar

    2014-01-01

    Full Text Available Objective. We aimed to compare the results of our initial robot-assisted nephron-sparing surgeries (RANSS performed with or without hilar clamping. Material and Method. Charts of the initial RANSSs (n=44, which were performed by a single surgeon, were retrospectively reviewed. R.E.N.A.L. nephrometry system, modified Clavien classification, and M.D.R.D. equation were used to record tumoral complexity, complications, and estimated glomerular filtration rate (eGFR, respectively. Outcomes of the clamped (group 1, n=14 versus off-clamp (group 2, n=30 RANSSs were compared. Results. The difference between the two groups was insignificant regarding mean patient age, mean tumor size, and mean R.E.N.A.L. nephrometry score. Mean operative time, mean estimated blood loss amount, and mean length of hospitalization were similar between groups. A total of 4 patients in each group suffered 11 Clavien grade ≥2 complications early postoperatively. Open conversion rates were similar. The difference between the 2 groups in terms of the mean postoperative change in eGFR was insignificant. We did not encounter any local recurrence after a mean follow-up of 18.9 months. Conclusions. Creating warm-ischemic conditions during RANSS should not be a liberal decision, even in the initial phases of the learning curve for a highly experienced open surgeon.

  9. Polarimetric signatures of a canopy of dielectric cylinders based on first and second order vector radiative transfer theory

    Science.gov (United States)

    Tsang, Leung; Chan, Chi Hou; Kong, Jin AU; Joseph, James

    1992-01-01

    Complete polarimetric signatures of a canopy of dielectric cylinders overlying a homogeneous half space are studied with the first and second order solutions of the vector radiative transfer theory. The vector radiative transfer equations contain a general nondiagonal extinction matrix and a phase matrix. The energy conservation issue is addressed by calculating the elements of the extinction matrix and the elements of the phase matrix in a manner that is consistent with energy conservation. Two methods are used. In the first method, the surface fields and the internal fields of the dielectric cylinder are calculated by using the fields of an infinite cylinder. The phase matrix is calculated and the extinction matrix is calculated by summing the absorption and scattering to ensure energy conservation. In the second method, the method of moments is used to calculate the elements of the extinction and phase matrices. The Mueller matrix based on the first order and second order multiple scattering solutions of the vector radiative transfer equation are calculated. Results from the two methods are compared. The vector radiative transfer equations, combined with the solution based on method of moments, obey both energy conservation and reciprocity. The polarimetric signatures, copolarized and depolarized return, degree of polarization, and phase differences are studied as a function of the orientation, sizes, and dielectric properties of the cylinders. It is shown that second order scattering is generally important for vegetation canopy at C band and can be important at L band for some cases.

  10. NEW CONCEPTS AND TEST METHODS OF CURVE PROFILE AREA DENSITY IN SURFACE: ESTIMATION OF AREAL DENSITY ON CURVED SPATIAL SURFACE

    OpenAIRE

    Hong Shen

    2011-01-01

    The concepts of curve profile, curve intercept, curve intercept density, curve profile area density, intersection density in containing intersection (or intersection density relied on intersection reference), curve profile intersection density in surface (or curve intercept intersection density relied on intersection of containing curve), and curve profile area density in surface (AS) were defined. AS expressed the amount of curve profile area of Y phase in the unit containing surface area, S...

  11. The Impact of Warm-Rain Microphysical Processes on Rain Rate and Polarimetric Observables at X-Band

    Science.gov (United States)

    Xie, Xinxin; Evaristo, Raquel; Troemel, Silke; Simmer, Clemens

    2015-04-01

    Microphysical processes govern the evolution of drop size distribution (DSD) during the development of precipitating systems. Thus, an accurate knowledge on precipitating systems from a microphysical perspective is required for better quantitative precipitation estimates (QPE). Additionally, detection of microphysical processes in 3D polarimetric radar volumes paves the way for better parameterizations in numerical weather predictions (NWP). In this study, we focus on the impact of different microphysical processes on rain rate (RR) and polarimetric observables at X band. Microphysical processes during the evolution of warm-rain precipitating systems, including size sorting, evaporation, coalescence and breakup, are taken into account. Assuming that vertical rain shaft is composed of liquid spheroids distributed in a normalized Gamma size distribution, microphysical processes are reconstructed. The variation of RR governed by microphysical processes is also examined. Unique fingerprints caused by microphysical processes have been identified in polarimetric radar observations. For size sorting, large rain drops concentrating near ground surface or at leading edge induce strong Zdr (differential reflectivity) accompanied by small Zh (reflectivity). A larger mean size in DSD results in stronger Zdr during size sorting. The increasing mean size due to evaporation and coalescence enhances Zdr, while Zh during evaporation is reduced by the depletion of small rain drops. The reduction of Zh ranges between -10 dB and 0 dB considering different DSDs during evaporation. Zh, Zdr and Kdp (specific differential phase) all decrease when large rain drops break up. The evolution of DSD which depends on the ongoing microphysical processes results in a variation in RR. Though size sorting due to differential sedimentation occurs, RR approaches stable within 15 min. Suffering from vertical wind shear, RR is reduced because of the categorization of rain drops with different terminal

  12. AirMOSS: L1 S-0 Polarimetric Data from AirMOSS P-band SAR, La Selva, 2012-2015

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides level 1 (L1) polarimetric radar backscattering coefficient (sigma-0), multilook complex, polarimetrically calibrated, and georeferenced data...

  13. INVENTORY OF IRRIGATED RICE ECOSYSTEM USING POLARIMETRIC SAR DATA

    Directory of Open Access Journals (Sweden)

    P. Srikanth

    2012-08-01

    Full Text Available An attempt has been made in the current study to assess the potential of polarimetric SAR data for inventory of kharif rice and the major competing crop like cotton. In the process, physical process of the scattering mechanisms occurring in rice and cotton crops at different phonological stages was studied through the use of temporal Radarsat 2 Fine quadpol SAR data. The temporal dynamics of the volume, double and odd bounce, entropy, anisotropy, alpha parameters and polarimertic signatures, classification through isodata clustering and Wishart techniques were assessed. The Wishart (H-a classification showed higher overall as well as rice and cotton crop accuracies compared to the isodata clustering from Freeman 3-component decomposition. The classification of temporal SAR data sets independently showed that the rice crop forecasting can be advanced with the use of appropriate single date polarimetric SAR data rather than using temporal SAR amplitude data sets with the single polarization in irrigated rice ecosystems

  14. Multispectral and polarimetric photodetection using a plasmonic metasurface

    Science.gov (United States)

    Pelzman, Charles; Cho, Sang-Yeon

    2018-01-01

    We present a metasurface-integrated Si 2-D CMOS sensor array for multispectral and polarimetric photodetection applications. The demonstrated sensor is based on the polarization selective extraordinary optical transmission from periodic subwavelength nanostructures, acting as artificial atoms, known as meta-atoms. The meta-atoms were created by patterning periodic rectangular apertures that support optical resonance at the designed spectral bands. By spatially separating meta-atom clusters with different lattice constants and orientations, the demonstrated metasurface can convert the polarization and spectral information of an optical input into a 2-D intensity pattern. As a proof-of-concept experiment, we measured the linear components of the Stokes parameters directly from captured images using a CMOS camera at four spectral bands. Compared to existing multispectral polarimetric sensors, the demonstrated metasurface-integrated CMOS system is compact and does not require any moving components, offering great potential for advanced photodetection applications.

  15. Three Dimensional Polarimetric Neutron Tomography of Magnetic Fields

    DEFF Research Database (Denmark)

    Sales, Morten; Strobl, Markus; Shinohara, Takenao

    2018-01-01

    -destructively with the potential to probe the interior of bulk samples which is not amenable otherwise. Using a pioneering polarimetric set-up for ToF neutron instrumentation in combination with a newly developed tailored reconstruction algorithm, the magnetic field generated by a current carrying solenoid has been measured......Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non...... and reconstructed, thereby providing the proof-of-principle of a technique able to reveal hitherto unobtainable information on the magnetic fields in the bulk of materials and devices, due to a high degree of penetration into many materials, including metals, and the sensitivity of neutron polarisation to magnetic...

  16. EMISAR: A Dual-frequency, Polarimetric Airborne SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2002-01-01

    . The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry....... Thermal control and several calibration loops have been built into the system to ensure system stability and absolute calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key......EMISAR is a fully polarimetric, dual frequency (L- and C-band) SAR system designed for remote sensing applications. The data are usually processed to 2×2 m resolution. The system has the capability of C-band cross-track single-pass interferometry and fully polarimetric repeat-pass interferometry...

  17. Retrieval of ice thickness from polarimetric SAR data

    Science.gov (United States)

    Kwok, R.; Yueh, S. H.; Nghiem, S. V.; Huynh, D. D.

    1993-01-01

    We describe a potential procedure for retrieving ice thickness from multi-frequency polarimetric SAR data for thin ice. This procedure includes first masking out the thicker ice types with a simple classifier and then deriving the thickness of the remaining pixels using a model-inversion technique. The technique used to derive ice thickness from polarimetric observations is provided by a numerical estimator or neural network. A three-layer perceptron implemented with the backpropagation algorithm is used in this investigation with several improved aspects for a faster convergence rate and a better accuracy of the neural network. These improvements include weight initialization, normalization of the output range, the selection of offset constant, and a heuristic learning algorithm. The performance of the neural network is demonstrated by using training data generated by a theoretical scattering model for sea ice matched to the database of interest. The training data are comprised of the polarimetric backscattering coefficients of thin ice and the corresponding input ice parameters to the scattering model. The retrieved ice thickness from the theoretical backscattering coefficients is compare with the input ice thickness to the scattering model to illustrate the accuracy of the inversion method. Results indicate that the network convergence rate and accuracy are higher when multi-frequency training sets are presented. In addition, the dominant backscattering coefficients in retrieving ice thickness are found by comparing the behavior of the network trained backscattering data at various incidence angels. After the neural network is trained with the theoretical backscattering data at various incidence anges, the interconnection weights between nodes are saved and applied to the experimental data to be investigated. In this paper, we illustrate the effectiveness of this technique using polarimetric SAR data collected by the JPL DC-8 radar over a sea ice scene.

  18. Change detection in a time series of polarimetric SAR data

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Skriver, Henning

    2014-01-01

    A test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution with an associated probability of finding a smaller value of the test statistic is introduced. Unlike tests based on pairwise comparisons between all temporally consecutive acquisi...... acquisitions the new omnibus test statistic and the probability measure successfully detects change in two short series of L- and C-band polarimetric EMISAR data....

  19. RADARSAT-2 Polarimetric Radar Imaging for Lake Ice Mapping

    Science.gov (United States)

    Pan, F.; Kang, K.; Duguay, C. R.

    2016-12-01

    Changes in lake ice dates and duration are useful indicators for assessing long-term climate trends and variability in northern countries. Lake ice cover observations are also a valuable data source for predictions with numerical ice and weather forecasting models. In recent years, satellite remote sensing has assumed a greater role in providing observations of lake ice cover extent for both modeling and climate monitoring purposes. Polarimetric radar imaging has become a promising tool for lake ice mapping at high latitudes where meteorological conditions and polar darkness severely limit observations from optical sensors. In this study, we assessed and characterized the physical scattering mechanisms of lake ice from fully polarimetric RADARSAT-2 datasets obtained over Great Bear Lake, Canada, with the intent of classifying open water and different ice types during the freeze-up and break-up periods. Model-based and eigen-based decompositions were employed to construct the coherency matrix into deterministic scattering mechanisms. These procedures as well as basic polarimetric parameters were integrated into modified convolutional neural networks (CNN). The CNN were modified via introduction of a Markov random field into the higher iterative layers of networks for acquiring updated priors and classifying ice and open water areas over the lake. We show that the selected polarimetric parameters can help with interpretation of radar-ice/water interactions and can be used successfully for water-ice segmentation, including different ice types. As more satellite SAR sensors are being launched or planned, such as the Sentinel-1a/b series and the upcoming RADARSAT Constellation Mission, the rapid volume growth of data and their analysis require the development of robust automated algorithms. The approach developed in this study was therefore designed with the intent of moving towards fully automated mapping of lake ice for consideration by ice services.

  20. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Directory of Open Access Journals (Sweden)

    J. Grazioli

    2015-01-01

    Full Text Available A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assigned to the appropriate hydrometeor class by means of human interpretation and comparisons with the output of other classification techniques. The main innovation in the proposed method is the unsupervised part: the hydrometeor classes are not defined a priori, but they are learned from data. The approach is applied to data collected by an X-band polarimetric weather radar during two field campaigns (from which about 50 precipitation events are used in the present study. Seven hydrometeor classes (nopt = 7 have been found in the data set, and they have been identified as light rain (LR, rain (RN, heavy rain (HR, melting snow (MS, ice crystals/small aggregates (CR, aggregates (AG, and rimed-ice particles (RI.

  1. Direct experimental evidence for a negative heat capacity in the liquid-to-gas like phase transition in hydrogen cluster ions backbending of the caloric curve

    CERN Document Server

    Gobet, F; Carré, M; Farizon, B; Farizon, M; Gaillard, M J; Maerk, T D; Scheier, P

    2002-01-01

    By (i) selecting specific decay reactions in high energy collisions (60 keV/amu) of hydrogen cluster ions with a helium target (utilizing event-by-event data of a recently developed multi-coincidence experiment) and by (ii) deriving corresponding temperatures for these microcanonical cluster ensembles (analyzing the respective fragment distributions) we are able to construct caloric curves for ii sub 3 sup + (ii sub 2) sub m cluster ions (6 <= m <= 14). All individual curves and the mean of these curves show a backbending in the plateau region thus constituting direct evidence for a negative microcanonical heat capacity in the liquid-to-gas like transition of these finite systems.

  2. Polarimetric mountain based radio-occultation for rain detection: The ROHP-PAZ ground campaign

    Science.gov (United States)

    Padulles, Ramon; Cardellach, Estel; Tomas, Sergio; de la Torre, Manuel; Turk, Joe

    2014-05-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) Radio-Occultation (RO) payload on board of the Spanish Earth Observation satellite PAZ. This will be a new technique that has never been tested before, that aims to improve the knowledge of precipitation through simultaneous thermodynamic and vertical rain profiles. Prior to the launch of the satellite, expected for 2014, a ground experimental campaign is being conducted with the goal of starting the process of identifying and understanding all the factors that might affect the polarimetric RO observables. The campaign is being carried out at the top of Puig Sesolles, a 1667m peak in the Natural Park of Montseny (41º46'24 N, 2º26'17 E), 50 km N-NE from Barcelona, with clear views over the horizon to the South (East to West) direction, an area in which intense precipitation events tend to occur a few times per year. The campaign uses a ICE-CSIC/IEEC's GOLD-RTR open-loop receiver initially designed for collecting GNSS signals reflected off the sea surface. The receiver has been adjusted to track occulting GNSS radio-links. A double polarization (H and V) GNSS antenna has been designed and manufactured by the Polytechnic University of Barcelona (UPC) team for this particular ground-based experiment. The antenna is a phase-array made of 7 elements, each of them being a square patch built using a Rogers 4003 substrate, and symmetrically fed by four probes. It provides a pattern of 12.9 dB peak gain, 45 degrees half-power beam-width, and <-35 dB cross-polar isolation at the peak (better than -30 dB in the main lobe). The preliminary results show that not only precipitation, but also other factors are affecting the GNSS signal, wich means that the polarimetric signal is richer than expected

  3. Integrating polarimetric synthetic aperture radar and imaging spectrometry for wildland fuel mapping in southern California

    Science.gov (United States)

    P.E. Dennison; D.A. Roberts; J. Regelbrugge; S.L. Ustin

    2000-01-01

    Polarimetric synthetic aperture radar (SAR) and imaging spectrometry exemplify advanced technologies for mapping wildland fuels in chaparral ecosystems. In this study, we explore the potential of integrating polarimetric SAR and imaging spectrometry for mapping wildland fuels. P-band SAR and ratios containing P-band polarizations are sensitive to variations in stand...

  4. Spectral Polarimetric Features Analysis of Wind Turbine Clutter in Weather Radar

    NARCIS (Netherlands)

    Yin, J.; Krasnov, O.A.; Unal, C.M.H.; Medagli, S.; Russchenberg, H.W.J.

    2017-01-01

    Wind turbine clutter has gradually become a concern for the radar community for its increasing size and quantity worldwide. Based on the S-band polarimetric Doppler PARSAX radar measurements, this paper demonstrates the micro-Doppler features and spectral-polarimetric characteristic of wind turbine

  5. Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle

    Directory of Open Access Journals (Sweden)

    Takashi Shibayama

    2015-11-01

    Full Text Available This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR, have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

  6. Ground-Based Polarimetric Remote Sensing of Dust Aerosol Properties in Chinese Deserts near Hexi Corridor

    Directory of Open Access Journals (Sweden)

    Hua Xu

    2014-01-01

    Full Text Available One-year observation of dust aerosol properties near Hexi Corridor was obtained from polarimetric measurements by ground-based sunphotometer in the county of Minqin in northwestern China from March 2012 to February 2013. We observed an annual mean AOD of 0.22±0.22 at 0.50 μm and Ångström exponents of 0.1–1.0 fitting a bimode normal distribution centered at 0.18 and 0.50, respectively. The effective radii of fine (0.13–0.17 μm and coarse (2.49–3.49 μm modes were found stable at all seasons together with the appearance of a third mode of particle radius at 0.4–1.0 μm when AOD was larger than 0.6. It is noticeable that the real (1.5–1.7 and imaginary (0.0005 to 0.09 parts of complex refractive indices were higher than other studies performed in other desert regions of China, while single scattering albedo was relatively lower (~0.84–0.89 at wavelengths of 0.44, 0.67, 0.87, and 1.02 μm. This is partially due to calcite or hematite in the soil in Minqin or the influence of anthropogenic aerosols containing carbon. Moreover, from our novel polarimetric measurement, the scattering phase function (F11 and degree of linear polarization for incident unpolarized light (-F12/F11 of dust aerosols were also obtained within this deserted area.

  7. Polsar Land Cover Classification Based on Hidden Polarimetric Features in Rotation Domain and Svm Classifier

    Science.gov (United States)

    Tao, C.-S.; Chen, S.-W.; Li, Y.-Z.; Xiao, S.-P.

    2017-09-01

    Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR) data utilization. Rollinvariant polarimetric features such as H / Ani / text-decoration: overline">α / Span are commonly adopted in PolSAR land cover classification. However, target orientation diversity effect makes PolSAR images understanding and interpretation difficult. Only using the roll-invariant polarimetric features may introduce ambiguity in the interpretation of targets' scattering mechanisms and limit the followed classification accuracy. To address this problem, this work firstly focuses on hidden polarimetric feature mining in the rotation domain along the radar line of sight using the recently reported uniform polarimetric matrix rotation theory and the visualization and characterization tool of polarimetric coherence pattern. The former rotates the acquired polarimetric matrix along the radar line of sight and fully describes the rotation characteristics of each entry of the matrix. Sets of new polarimetric features are derived to describe the hidden scattering information of the target in the rotation domain. The latter extends the traditional polarimetric coherence at a given rotation angle to the rotation domain for complete interpretation. A visualization and characterization tool is established to derive new polarimetric features for hidden information exploration. Then, a classification scheme is developed combing both the selected new hidden polarimetric features in rotation domain and the commonly used roll-invariant polarimetric features with a support vector machine (SVM) classifier. Comparison experiments based on AIRSAR and multi-temporal UAVSAR data demonstrate that compared with the conventional classification scheme which only uses the roll-invariant polarimetric features, the proposed classification scheme achieves both higher classification accuracy and better robustness. For AIRSAR data, the overall classification

  8. Combined interferometric and polarimetric diagnostics for TEXTOR

    International Nuclear Information System (INIS)

    Soltwisch, H.

    1980-01-01

    A method for combining Faraday rotation measurements with a phase modulated HCN interferometer is described. Extended to a multichannel system this technique should allow to investigate the distributions of electron density and poloidal magnetic field in a Tokamak plasma. We discuss the principle of operation and appropriate evaluation of measured data with regard to TEXTOR parameters and give an estimate for the expected experimental accuracy. (orig./GG) 891 GG/orig.- 892 KN

  9. PHARUS : PHased ARray Universal SAR

    NARCIS (Netherlands)

    Paquay, M.H.A.; Vermeulen, B.C.B.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

    1996-01-01

    In the Netherlands, a polarimetric C-band aircraft SAR (Synthetic Aperture Radar) has been developed. The project is called PHARUS, an acronm for PHased ARray Universal SAR. This instrument serves remote sensing applications. The antenna system contains 48 active modules (expandable to 96). A module

  10. Microphysical retrievals from simultaneous polarimetric and profiling radar observations

    Directory of Open Access Journals (Sweden)

    M. P. Morris

    2009-12-01

    Full Text Available The character of precipitation detected at the surface is the final product of many microphysical interactions in the cloud above, the combined effects of which may be characterized by the observed drop size distribution (DSD. This necessitates accurate retrieval of the DSD from remote sensing data, especially radar as it offers large areal coverage, high spatial resolution, and rigorous quality control and testing. Combined instrument observations with a UHF wind profiler, an S-band polarimetric weather radar, and a video disdrometer are analyzed for two squall line events occuring during the calendar year 2007. UHF profiler Doppler velocity spectra are used to estimate the DSD aloft, and are complemented by DSDs retrieved from an exponential model applied to polarimetric data. Ground truth is provided by the disdrometer. A complicating factor in the retrieval from UHF profiler spectra is the presence of ambient air motion, which can be corrected using the method proposed by Teshiba et al. (2009, in which a comparison between idealized Doppler spectra calculated from the DSDs retrieved from KOUN and those retrieved from contaminated wind profiler spectra is performed. It is found that DSDs measured using the distrometer at the surface and estimated using the wind profiler and polarimetric weather radar generally showed good agreement. The DSD retrievals using the wind profiler were improved when the estimates of the vertical wind were included into the analysis, thus supporting the method of Teshiba et al. (2009. Furthermore, the the study presents a method of investigating the time and height structure of DSDs.

  11. Polarimetric purity and the concept of degree of polarization

    Science.gov (United States)

    Gil, José J.; Norrman, Andreas; Friberg, Ari T.; Setälä, Tero

    2018-02-01

    The concept of degree of polarization for electromagnetic waves, in its general three-dimensional version, is revisited in the light of the implications of the recent findings on the structure of polarimetric purity and of the existence of nonregular states of polarization [J. J. Gil et al., Phys Rev. A 95, 053856 (2017), 10.1103/PhysRevA.95.053856]. From the analysis of the characteristic decomposition of a polarization matrix R into an incoherent convex combination of (1) a pure state Rp, (2) a middle state Rm given by an equiprobable mixture of two eigenstates of R, and (3) a fully unpolarized state Ru -3 D, it is found that, in general, Rm exhibits nonzero circular and linear degrees of polarization. Therefore, the degrees of linear and circular polarization of R cannot always be assigned to the single totally polarized component Rp. It is shown that the parameter P3 D proposed formerly by Samson [J. C. Samson, Geophys. J. R. Astron. Soc. 34, 403 (1973), 10.1111/j.1365-246X.1973.tb02404.x] takes into account, in a proper and objective form, all the contributions to polarimetric purity, namely, the contributions to the linear and circular degrees of polarization of R as well as to the stability of the plane containing its polarization ellipse. Consequently, P3 D constitutes a natural representative of the degree of polarimetric purity. Some implications for the common convention for the concept of two-dimensional degree of polarization are also analyzed and discussed.

  12. Beaconless search and rescue using polarimetric synthetic aperture radar

    Science.gov (United States)

    McCandless, Samuel W.; Huxtable, Barton D.; Mansfield, Arthur W.; Wallace, Ronald; Larsen, Rudolph; Rais, Houra

    1996-03-01

    In developing a beaconless search and rescue capability to quickly locate small aircraft that have crashed in remote areas, NASA's Search and Rescue (S&R) Program brings together advanced polarimetric synthetic aperture radar processing, field and laboratory tests, and state-of-the-art automated target detection algorithms. This paper provides the status of this program, which began with experiments conducted in concert with the JPL DC-8 AirSAR in 1989 at the Duke University Forest. The program is being conducted by NASA's Goddard Space Flight Center (GSFC) under the auspices of the Search and Rescue Office.

  13. HAWC+/SOFIA Polarimetric Observations of OMC-1

    Science.gov (United States)

    Chuss, David; Andersson, B.-G.; Bally, John; Dowell, Charles D.; Harper, Doyal; Lazarian, Alex; Michail, Joseph M.; Morris, Mark; Novak, Giles; Siah, Javad; Vaillancourt, John; Werner, Michael; HAWC+ Science Team

    2018-01-01

    Astrophysical dust grains become partially aligned due to magnetic fields that permeate the interstellar medium. Measurements of far-infrared polarized emission provide a tool to characterize magnetic fields and test their effect on star formation in molecular clouds. The HAWC+ camera provides polarimetric imaging capability for SOFIA in four bands between 50 and 300 microns. As part of the science commissioning of the instrument, HAWC+ has obtained more than 1000 independent measurements of polarization in the OMC-1 star forming region. The observations were made at a wavelength of 89 microns with an angular resolution of 8 arcseconds. We present these preliminary data and initial analysis.

  14. Three axis vector atomic magnetometer utilizing polarimetric technique

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Swarupananda, E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India and Homi Bhabha National Institute, Department of Atomic Energy, Mumbai 400094 (India)

    2016-09-15

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  15. Lagrangian Curves on Spectral Curves of Monopoles

    International Nuclear Information System (INIS)

    Guilfoyle, Brendan; Khalid, Madeeha; Ramon Mari, Jose J.

    2010-01-01

    We study Lagrangian points on smooth holomorphic curves in TP 1 equipped with a natural neutral Kaehler structure, and prove that they must form real curves. By virtue of the identification of TP 1 with the space LE 3 of oriented affine lines in Euclidean 3-space, these Lagrangian curves give rise to ruled surfaces in E 3 , which we prove have zero Gauss curvature. Each ruled surface is shown to be the tangent lines to a curve in E 3 , called the edge of regression of the ruled surface. We give an alternative characterization of these curves as the points in E 3 where the number of oriented lines in the complex curve Σ that pass through the point is less than the degree of Σ. We then apply these results to the spectral curves of certain monopoles and construct the ruled surfaces and edges of regression generated by the Lagrangian curves.

  16. Curves from Motion, Motion from Curves

    Science.gov (United States)

    2000-01-01

    tautochrone and brachistochrone properties. To Descartes, however, the rectification of curves such as the spiral (3) and the cycloid (4) was suspect - they...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012017 TITLE: Curves from Motion, Motion from Curves DISTRIBUTION...Approved for public release, distribution unlimited This paper is part of the following report: TITLE: International Conference on Curves and Surfaces [4th

  17. Ship Discrimination Using Polarimetric SAR Data and Coherent Time-Frequency Analysis

    Directory of Open Access Journals (Sweden)

    Canbin Hu

    2013-12-01

    Full Text Available This paper presents a new approach for the discrimination of ship responses using polarimetric SAR (PolSAR data. The PolSAR multidimensional information is analyzed using a linear Time-Frequency (TF decomposition approach, which permits to describe the polarimetric behavior of a ship and its background area for different azimuthal angles of observation and frequencies of illumination. This paper proposes to discriminate ships from their background by using characteristics of their polarimetric TF responses, which may be associated with the intrinsic nature of the observed natural or artificial scattering structures. A statistical descriptor related to polarimetric coherence of the signal in the TF domain is proposed for detecting ships in different complex backgrounds, including SAR azimuth ambiguities, artifacts, and small natural islands, which may induce numerous false alarms. Choices of the TF analysis direction, i.e., along separate azimuth or range axis, or simultaneously in both directions, are investigated and evaluated. TF decomposition modes including range direction perform better in terms of discriminating ships from range focusing artifacts. In comparison with original full-resolution polarimetric indicators, the proposed TF polarimetric coherence descriptor is shown to qualitatively enhance the ship/background contrast and improve discrimination capabilities. Using polarimetric RADARSAT-2 data acquired over complex scenes, experimental results demonstrate the efficiency of this approach in terms of ship location retrieval and response characterization.

  18. Multi-Frequency Polarimetric SAR Classification Based on Riemannian Manifold and Simultaneous Sparse Representation

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2015-07-01

    Full Text Available Normally, polarimetric SAR classification is a high-dimensional nonlinear mapping problem. In the realm of pattern recognition, sparse representation is a very efficacious and powerful approach. As classical descriptors of polarimetric SAR, covariance and coherency matrices are Hermitian semidefinite and form a Riemannian manifold. Conventional Euclidean metrics are not suitable for a Riemannian manifold, and hence, normal sparse representation classification cannot be applied to polarimetric SAR directly. This paper proposes a new land cover classification approach for polarimetric SAR. There are two principal novelties in this paper. First, a Stein kernel on a Riemannian manifold instead of Euclidean metrics, combined with sparse representation, is employed for polarimetric SAR land cover classification. This approach is named Stein-sparse representation-based classification (SRC. Second, using simultaneous sparse representation and reasonable assumptions of the correlation of representation among different frequency bands, Stein-SRC is generalized to simultaneous Stein-SRC for multi-frequency polarimetric SAR classification. These classifiers are assessed using polarimetric SAR images from the Airborne Synthetic Aperture Radar (AIRSAR sensor of the Jet Propulsion Laboratory (JPL and the Electromagnetics Institute Synthetic Aperture Radar (EMISAR sensor of the Technical University of Denmark (DTU. Experiments on single-band and multi-band data both show that these approaches acquire more accurate classification results in comparison to many conventional and advanced classifiers.

  19. Polarimetric LIDAR with FRI sampling for target characterization

    Science.gov (United States)

    Wijerathna, Erandi; Creusere, Charles D.; Voelz, David; Castorena, Juan

    2017-09-01

    Polarimetric LIDAR is a significant tool for current remote sensing applications. In addition, measurement of the full waveform of the LIDAR echo provides improved ranging and target discrimination, although, data storage volume in this approach can be problematic. In the work presented here, we investigated the practical issues related to the implementation of a full waveform LIDAR system to identify polarization characteristics of multiple targets within the footprint of the illumination beam. This work was carried out on a laboratory LIDAR testbed that features a flexible arrangement of targets and the ability to change the target polarization characteristics. Targets with different retardance characteristics were illuminated with a linearly polarized laser beam and the return pulse intensities were analyzed by rotating a linear analyzer polarizer in front of a high-speed detector. Additionally, we explored the applicability and the limitations of applying a sparse sampling approach based on Finite Rate of Innovations (FRI) to compress and recover the characteristic parameters of the pulses reflected from the targets. The pulse parameter values extracted by the FRI analysis were accurate and we successfully distinguished the polarimetric characteristics and the range of multiple targets at different depths within the same beam footprint. We also demonstrated the recovery of an unknown target retardance value from the echoes by applying a Mueller matrix system model.

  20. Measurement of impulse current using polarimetric fiber optic sensor

    Science.gov (United States)

    Ginter, Mariusz

    2017-08-01

    In the paper the polarimetric current sensing solution used for measurements of high amplitude currents and short durations is presented. This type of sensor does not introduce additional resistance and inductance into the circuit, which is a desirable phenomenon in this type of measurement. The magneto element is a fiber optic coil made of spun fiber optic. The fiber in which the core is twisted around its axis is characterized by a small effect of interfering magnitudes, ie mechanical vibrations and pressure changes on the polarimeter. The presented polarimetric current sensor is completely fiber optic. Experimental results of a proposed sensor construction solution operating at 1550 nm and methods of elimination of influence values on the fiber optic current sensor were presented. The sensor was used to measure the impulse current. The generated current pulses are characterized by a duration of 23μs and amplitudes ranging from 1 to 3.5 kA. The currents in the discharge circuit are shown. The measurement uncertainty of the amplitude of the electric current in the range of measured impulses was determined and estimated to be no more than 2%.

  1. G0-WISHART Distribution Based Classification from Polarimetric SAR Images

    Science.gov (United States)

    Hu, G. C.; Zhao, Q. H.

    2017-09-01

    Enormous scientific and technical developments have been carried out to further improve the remote sensing for decades, particularly Polarimetric Synthetic Aperture Radar(PolSAR) technique, so classification method based on PolSAR images has getted much more attention from scholars and related department around the world. The multilook polarmetric G0-Wishart model is a more flexible model which describe homogeneous, heterogeneous and extremely heterogeneous regions in the image. Moreover, the polarmetric G0-Wishart distribution dose not include the modified Bessel function of the second kind. It is a kind of simple statistical distribution model with less parameter. To prove its feasibility, a process of classification has been tested with the full-polarized Synthetic Aperture Radar (SAR) image by the method. First, apply multilook polarimetric SAR data process and speckle filter to reduce speckle influence for classification result. Initially classify the image into sixteen classes by H/A/α decomposition. Using the ICM algorithm to classify feature based on the G0-Wshart distance. Qualitative and quantitative results show that the proposed method can classify polaimetric SAR data effectively and efficiently.

  2. Algorithm for wind speed estimate with polarimetric radar

    Directory of Open Access Journals (Sweden)

    Ю. А. Авер’янова

    2013-07-01

    Full Text Available The connection of wind speed and drops behavior is substantiated as well as the drop behavior influence onto the polarization characteristics of electromagnetic waves. The expression to calculate the wind speed taking into account the Weber number for the critical regime of drop deformation is obtained. The critical regime of drop deformation is the regime when drop is divided into two parts. The dependency of critical wind speed on the drop diameter is calculated and shown. The concept o polarization spectrum that is introduced in the previous papers is used to estimate the dynamic processes in the atmosphere. At the moment when the drop is under the influence of the wind that is equal to the critical wind speed the drop will be divided into two parts. This process will be reflected as the appearance of the two equal components of polarization spectra of reflected electromagnetic waves at the orthogonal antennas of Doppler Polarimetric Radar. Owing the information about the correspondence of the polarization component energy level to the drop diameter it is possible to estimate the wind speed with the obtained dependency. The process of the wind speed estimate with polarimetric radar is presented with the developed common algorithm

  3. Dual-Polarized Planar Phased Array Analysis for Meteorological Applications

    Directory of Open Access Journals (Sweden)

    Chen Pang

    2015-01-01

    Full Text Available This paper presents a theoretical analysis for the accuracy requirements of the planar polarimetric phased array radar (PPPAR in meteorological applications. Among many factors that contribute to the polarimetric biases, four factors are considered and analyzed in this study, namely, the polarization distortion due to the intrinsic limitation of a dual-polarized antenna element, the antenna pattern measurement error, the entire array patterns, and the imperfect horizontal and vertical channels. Two operation modes, the alternately transmitting and simultaneously receiving (ATSR mode and the simultaneously transmitting and simultaneously receiving (STSR mode, are discussed. For each mode, the polarimetric biases are formulated. As the STSR mode with orthogonal waveforms is similar to the ATSR mode, the analysis is mainly focused on the ATSR mode and the impacts of the bias sources on the measurement of polarimetric variables are investigated through Monte Carlo simulations. Some insights of the accuracy requirements are obtained and summarized.

  4. REMOVAL OF SPECTRO-POLARIMETRIC FRINGES BY TWO-DIMENSIONAL PATTERN RECOGNITION

    International Nuclear Information System (INIS)

    Casini, R.; Judge, P. G.; Schad, T. A.

    2012-01-01

    We present a pattern-recognition-based approach to the problem of the removal of polarized fringes from spectro-polarimetric data. We demonstrate that two-dimensional principal component analysis can be trained on a given spectro-polarimetric map in order to identify and isolate fringe structures from the spectra. This allows us, in principle, to reconstruct the data without the fringe component, providing an effective and clean solution to the problem. The results presented in this paper point in the direction of revising the way that science and calibration data should be planned for a typical spectro-polarimetric observing run.

  5. Correlation methods for the analysis of X-ray polarimetric signals

    Science.gov (United States)

    Massaro, E.; Fabiani, S.; Campana, R.; Costa, E.; Del Monte, E.; Muleri, F.; Soffitta, P.

    2018-03-01

    X-ray polarimetric measurements are based on studying the distribution of the directions of scattered photons or photoelectrons and on the search of a sinusoidal modulation with a period of π. We developed two tools for investigating these angular distributions based on the correlations between counts in phase bins separated by fixed phase distances. In one case we use the correlation between data separated by half of the bin number (one period) which is expected to give a linear pattern. In the other case, the scatter plot obtained by shifting by 1/8 of the bin number (1/4 of period) transforms the sinusoid in a circular pattern whose radius is equal to the amplitude of the modulation. For unpolarized radiation these plots are reduced to a random point distribution centred at the mean count level. This new methods provide direct visual and simple statistical tools for evaluating the quality of polarization measurements and for estimating the polarization parameters. Furthermore they are useful for investigating distortions due to systematic effects.

  6. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobile X-band Polarimetric Weather Radar on Wheels (X-POW)is a Doppler scanning radar operating at 9.3 GHz.with horizontal and vertical polarization. Used for...

  7. GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar OLYMPEX V2

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar OLYMPEX V2 dataset consists of rain rate, reflectivity, Doppler velocity, and other...

  8. GPM GROUND VALIDATION NASA S-BAND DUAL POLARIMETRIC (NPOL) DOPPLER RADAR IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar IFloodS data set was collected from April 30, 2013 to June 16, 2013 near Traer, Iowa as...

  9. GPM GROUND VALIDATION IOWA X-BAND POLARIMETRIC MOBILE DOPPLER WEATHER RADARS IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Iowa X-band Polarimetric Mobile Doppler Weather Radars IFloodS dataset was gathered during the IFloodS campaign from April to June 2013...

  10. CLPX-Airborne: Polarimetric Ku-Band Scatterometer (POLSCAT) Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Ku-band polarimetric scatterometer (POLSCAT) data collected as part of the Cold Land Processes Field Experiment (CLPX) to enable the...

  11. Multiphasic growth curve analysis.

    NARCIS (Netherlands)

    Koops, W.J.

    1986-01-01

    Application of a multiphasic growth curve is demonstrated with 4 data sets, adopted from literature. The growth curve used is a summation of n logistic growth functions. Human height growth curves of this type are known as "double logistic" (n = 2) and "triple logistic" (n = 3) growth curves (Bock

  12. How much cooler would it be with some more neutrons? Exploring the asymmetry dependence of the nuclear caloric curve and the liquid-gas phase transition

    International Nuclear Information System (INIS)

    McIntosh, A.B.; Mabiala, J.; Hagel, K.; Bonasera, A.; Cammarata, P.; Heilborn, L.; May, L.W.; Raphelt, A.; Wuenschel, S.; Zarrella, A.; Yennello, S.J.; Kohley, Z.; Marini, P.; Souliotis, G.A.; Zheng, H.

    2014-01-01

    Despite the long-standing interest in the symmetry energy by the nuclear physics community, much work remains to characterize the equation of state away from the valley of stability and normal density. Although the correlations between the thermodynamic properties (temperature, density, pressure) has been explored, the dependence of these correlations on the neutron-proton asymmetry has only recently been probed experimentally. In this work, we provide evidence for the asymmetry dependence of the nuclear caloric curve using multiple independent probes. Correlations between the temperature, density and pressure when normalized to their critical values exhibit scaling, allowing extraction of the critical point. The location of the critical point shows a dependence on the neutron-proton asymmetry. (orig.)

  13. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    OpenAIRE

    Raupach, Timothy H.; Berne, Alexis

    2016-01-01

    A new technique for estimating the raindrop size distribution (DSD) from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observation...

  14. Polarimetric SAR image classification based on discriminative dictionary learning model

    Science.gov (United States)

    Sang, Cheng Wei; Sun, Hong

    2018-03-01

    Polarimetric SAR (PolSAR) image classification is one of the important applications of PolSAR remote sensing. It is a difficult high-dimension nonlinear mapping problem, the sparse representations based on learning overcomplete dictionary have shown great potential to solve such problem. The overcomplete dictionary plays an important role in PolSAR image classification, however for PolSAR image complex scenes, features shared by different classes will weaken the discrimination of learned dictionary, so as to degrade classification performance. In this paper, we propose a novel overcomplete dictionary learning model to enhance the discrimination of dictionary. The learned overcomplete dictionary by the proposed model is more discriminative and very suitable for PolSAR classification.

  15. Estimating soil moisture using the Danish polarimetric SAR

    DEFF Research Database (Denmark)

    Jiankang, Ji; Thomsen, A.; Skriver, Henning

    1995-01-01

    The results of applying data from the Danish polarimetric SAR (EMISAR) to estimate soil moisture for bare fields are presented. Fully calibrated C-band SAR images for hh, vv and cross polarizations have been used in this study. The measured surface roughness data showed that classical roughness...... autocorrelation functions (Gaussian and Exponential) were not able to fit natural surfaces well. A Gauss-Exp hybrid model which agreed better with the measured data has been proposed. Theoretical surface scattering models (POM, IEM), as well as an empirical model for retrieval of soil moisture and surface rms...... height from coand cross-polarized ratio, have been examined, but the results are less satisfactory. As soil moisture response to backscattering coefficient σo is mainly coupled to surface roughness effect for bare fields, a bilinear model coupling volumetric soil moisture mv and surface rms height σ...

  16. Scattering Mechanism Identification Based on Polarimetric HRRP of Manmade Target

    Directory of Open Access Journals (Sweden)

    Wu Jiani

    2016-04-01

    Full Text Available In this paper, we analyze the space polarization and frequency dispersion characteristics of the polarimetric High Resolution Range Profile (HRRP of manmade targets. We integrate these characteristics and propose a novel scheme for scattering mechanism identification. Using a polarization decomposition technique, the scheme first identifies the scattering mechanism of the scattering centers. Specially, it uses an algorithm to compensate for the polarization orientation angle in order to decrease the errors in judgment caused by the varying azimuth. Then, based on the frequency dispersion characteristics, we design threedimensional parameters to discriminate between the scattering centers, in order to decrease the inaccuracy in the discriminations. Finally, we conduct simulations based on electromagnetic data to validate the feasibility of the proposed scheme and to demonstrate that it provides a basis for practical use in target recognition.

  17. Classification of Polarimetric SAR Data Using Dictionary Learning

    DEFF Research Database (Denmark)

    Vestergaard, Jacob Schack; Nielsen, Allan Aasbjerg; Dahl, Anders Lindbjerg

    2012-01-01

    This contribution deals with classification of multilook fully polarimetric synthetic aperture radar (SAR) data by learning a dictionary of crop types present in the Foulum test site. The Foulum test site contains a large number of agricultural fields, as well as lakes, forests, natural vegetation......, grasslands and urban areas, which make it ideally suited for evaluation of classification algorithms. Dictionary learning centers around building a collection of image patches typical for the classification problem at hand. This requires initial manual labeling of the classes present in the data and is thus...... a method for supervised classification. Sparse coding of these image patches aims to maintain a proficient number of typical patches and associated labels. Data is consecutively classified by a nearest neighbor search of the dictionary elements and labeled with probabilities of each class. Each dictionary...

  18. Analytical Aspects of Total Starch Polarimetric Determination in Some Cereals

    Directory of Open Access Journals (Sweden)

    Rodica Caprita

    2016-10-01

    Full Text Available Starch is the most important digestible polysaccharide present in foods and feeds. The starch concentration in cereals cannot be determined directly, because the starch is contained within a structurally and chemically complex matrix. Fine grinding and boiling in dilute HCl are preparative steps necessary for complete release of the starch granules from the protein matrix. Starch can be determined using simple and inexpensive physical methods, such as density, refractive index or optical rotation assessment. The polarimetric method allows the determination even of small starch contents due to its extremely high specific rotation. For more accurate results, the contribution of free sugars is eliminated by dissolution in 40% (V/V ethanol. The influence of other optically active substances, which might interfere, is removed by filtration/clarification prior to the optical rotation measurement.

  19. Tropical Mangrove Mapping Using Fully-Polarimetric Radar Data

    Directory of Open Access Journals (Sweden)

    Bambang Trisasongko

    2009-09-01

    Full Text Available Although mangrove is one of important ecosystems in the world, it has been abused and exploited by human for various purposes. Monitoring mangrove is therefore required to maintain a balance between economy and conservation and provides up-to-date information for rehabilitation. Optical remote sensing data have delivered such information, however ever-changing atmospheric disturbance may significantly decrease thematic content. In this research, Synthetic Aperture Radar (SAR fully polarimetric data were evaluated to present an alternative for mangrove mapping. Assessment using three statistical trees was performed on both tonal and textural data. It was noticeable that textural data delivered fairly good improvement which reduced the error rate to around 5-6% at L-band. This suggests that insertion of textural data is more important than any information derived from decomposition algorithm.

  20. Segment-based change detection for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2006-01-01

    single-channel SAR images but multi-channel algorithms have also been described. Different approaches have been used for image segmentation. Edge detection combined with region growing is one approach, where segments are created by growing regions from a previously edge detected and edge thinned image....... This method relies primarily on a robust edge detector, which preferably provides a constant false alarm rate. For single-channel SAR images this is fulfilled by the ratio edge detector, and for polarimetric SAR data, an edge detector based on the above mentioned test statistic fulfils this. Another approach......, wetlands, lakes, and urban areas. Also, other test sites over for instance urban areas have been used to assess the improvement by the segment-based change detection method. In the paper, results from pixel-based change detection, i.e. without segmentation, and from segment-based change detection, where...

  1. Polarimetric Exploration of Solar System Small Bodies: Search for Habitability

    Science.gov (United States)

    Yanamandra-Fisher, Padma A.

    2015-08-01

    The overarching goals for the remote sensing and robotic exploration of our solar system and exoplanetary systems are: (1) understanding the formation of planetary systems and their diversity; and (2) search for habitability. These goals can be realized with the inclusion of spectrophotopolarimetry as a complementary approach to standard techniques of imaging and spectroscopy. Since all objects have unique polarimetric signatures, like fingerprints, much can be learned about the scattering object. Although polarization, in general, is elliptical by nature, special cases such as linear and circular polarimetric signatures provide insight into the various types of scattering media and are valuable tools to be developed. Additionally, spectral dependence of polarization is important to separate the macroscopic (bulk) properties of the scattering medium from the microscopic (particulate) properties of the scattering medium. The search for habitability can benefit from spectrophotopolarimetry. While linear polarization of reflected light by solar system objects (planetary atmospheres, satellites, rings systems, comets, asteroids, dust, etc.) provides insight into the scattering characteristics of aerosols and hazes in atmospheres and surficial properties of atmosphereless objects, circular polarization and related chirality) or handedness, a property of molecules that exhibit mirror-image symmetry, similar to right and left hands) can serve as diagnostic of biological activity. All known life forms on earth are chiral and pre-dominantly left-handed. However, many of these applications suffer from lack of detailed observations, instrumentation, dedicated missions and numerical/retrieval methods. I will present a review of the field, with advances made in instrumentation, measurements and applications to prospective missions.

  2. An improved method for polarimetric image restoration in interferometry

    Science.gov (United States)

    Pratley, Luke; Johnston-Hollitt, Melanie

    2016-11-01

    Interferometric radio astronomy data require the effects of limited coverage in the Fourier plane to be accounted for via a deconvolution process. For the last 40 years this process, known as `cleaning', has been performed almost exclusively on all Stokes parameters individually as if they were independent scalar images. However, here we demonstrate for the case of the linear polarization P, this approach fails to properly account for the complex vector nature resulting in a process which is dependent on the axes under which the deconvolution is performed. We present here an improved method, `Generalized Complex CLEAN', which properly accounts for the complex vector nature of polarized emission and is invariant under rotations of the deconvolution axes. We use two Australia Telescope Compact Array data sets to test standard and complex CLEAN versions of the Högbom and SDI (Steer-Dwedney-Ito) CLEAN algorithms. We show that in general the complex CLEAN version of each algorithm produces more accurate clean components with fewer spurious detections and lower computation cost due to reduced iterations than the current methods. In particular, we find that the complex SDI CLEAN produces the best results for diffuse polarized sources as compared with standard CLEAN algorithms and other complex CLEAN algorithms. Given the move to wide-field, high-resolution polarimetric imaging with future telescopes such as the Square Kilometre Array, we suggest that Generalized Complex CLEAN should be adopted as the deconvolution method for all future polarimetric surveys and in particular that the complex version of an SDI CLEAN should be used.

  3. Assessment of GF-3 Polarimetric SAR Data for Physical Scattering Mechanism Analysis and Terrain Classification.

    Science.gov (United States)

    Yin, Junjun; Yang, Jian; Zhang, Qingjun

    2017-12-01

    On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric SAR can fully characterize the backscatter property of targets, and thus it is of great interest to explore the physical scattering mechanisms of terrain types, which is very important in interpreting polarimetric SAR imagery and for its further usages in Earth observations. In this paper, focusing on target scattering characterization and feature extraction, we generalize the Δ α B / α B method, which was proposed under the reflection symmetric assumption, for the general backscatter process to account for both the reflection symmetry and asymmetry cases. Then, we evaluate the performances of physical scattering mechanism analysis methods for GF-3 polarimetric SAR imagery. Radarsat-2 data acquired over the same area is used for cross validation. Results show that GF-3 polarimetric SAR data has great potential for target characterization, especially for ocean area observation.

  4. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    Directory of Open Access Journals (Sweden)

    Pottier E.

    2010-06-01

    Full Text Available SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height

  5. Classification of Forest Regrowth Stage using Polarimetric Decomposition and Foliage Projective Cover

    Science.gov (United States)

    Clewley, D.; Lucas, R.; Bunting, P.; Moghaddam, M.

    2012-12-01

    Within Queensland, Australia extensive clearing of vegetation for agriculture has occurred within the Brigalow Belt Bioregion (BBB), reducing forests dominated by Acacia harpophylla (brigalow) to 10 % of their former extent. Where cleared land is left abandoned or unmanaged regeneration is rapid, Regenerating vegetation represents a more efficient and cost effective method for carbon sequestration than direct planting and offers a number of benefits over plantation forest, particularly in terms of provision of habitat for native fauna. To effectively protect regenerating vegetation, maps of the distribution of forests at different stages of regeneration are required. Whilst mapping approaches have traditionally focused on optical data, the high canopy cover of brigalow regrowth in all but the very early stages limits discrimination of forests at different stages of growth. The combination of optical data, namely Landsat derived Foliage Projective Cover (FPC) and Advanced Land Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (SAR) backscatter data have previously been investigated for mapping regrowth. This study therefore aimed to investigate the potential of the alpha-Entropy (α/H) decomposition (S Cloude and E Pottier, "An entropy based classification scheme for land applications of polarimetric SAR," 1997, IEEE Transactions on Geoscience and Remote Sensing, vol. 35, no. 1, pp. 68-78) applied to polarimetric ALOS PALSAR backscatter for mapping regrowth stage combined with FPC data to account for canopy variations. The study focused on the Tara Downs subregion, located in the Western Darling Downs, within the south of the BBB. PALSAR data were acquired over the study site in fully-polarimetric mode (incidence angle mid swath ~ 26 degrees). From these data α/H layers were generated and stacked with FPC data. Considering only those areas known to contain brigalow prior to clearing and with an FPC > 9 %, k-means clustering was applied, with

  6. Structural Classification of Marshes with Polarimetric SAR Highlighting the Temporal Mapping of Marshes Exposed to Oil

    Directory of Open Access Journals (Sweden)

    Elijah Ramsey

    2015-09-01

    Full Text Available Empirical relationships between field-derived Leaf Area Index (LAI and Leaf Angle Distribution (LAD and polarimetric synthetic aperture radar (PolSAR based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.

  7. Full Polarimetric Synthetic Aperture Radar (SAR) Data for ionosphere observation - A comparative study

    Science.gov (United States)

    Mohanty, S.; Singh, G.

    2017-12-01

    Ionosphere, predominantly, govern the propagation of radio waves, especially at L-band and lower frequencies. Small-scale, rapid fluctuations in the electron density, termed as scintillation phenomenon, cause rapid variations in signal amplitude and phase. Scintillation studies have been done using ground-based radio transmitter and beacon GPS signals. In this work, attempt has been made to utilize full polarimetric synthetic aperture radar (SAR) satellite signal at L-band (1.27 GHz) to develop a new measurement index for SAR signal intensity fluctuation. Datasets acquired from Japan's latest Advanced Land Observation Satellite (ALOS)-2 over the Indian subcontinent on two different dates, with varying ionospheric activities, have been utilized to compare the index. A 20% increase in the index values for a scintillation-affected day has been observed. The result coincides with the nature of ionospheric scintillation pattern typically observed over the equatorial belt. Total electron content values, for the two dates of acquisition, obtained from freely available Ionosphere Exchange (IONEX) data have been used to validate the varying ionospheric activities as well as the trend in index results. Another interesting finding of the paper is the demarcation of the equatorial anomaly belt. The index values are comparatively higher at these latitudes on a scintillation-affected day. Furthermore, the SAR signal intensity fluctuation index has great potential in being used as a preliminary measurement index to identify low frequency SAR data affected by ionospheric scintillation.

  8. Structural classification of marshes with Polarimetric SAR highlighting the temporal mapping of marshes exposed to oil

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.

    2015-01-01

    Empirical relationships between field-derived Leaf Area Index (LAI) and Leaf Angle Distribution (LAD) and polarimetric synthetic aperture radar (PolSAR) based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC) correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.             

  9. Four-Component Scattering Power Decomposition Algorithm with Rotation of Covariance Matrix Using ALOS-PALSAR Polarimetric Data

    Directory of Open Access Journals (Sweden)

    Yasuhiro Nakamura

    2012-07-01

    Full Text Available The present study introduces the four-component scattering power decomposition (4-CSPD algorithm with rotation of covariance matrix, and presents an experimental proof of the equivalence between the 4-CSPD algorithms based on rotation of covariance matrix and coherency matrix. From a theoretical point of view, the 4-CSPD algorithms with rotation of the two matrices are identical. Although it seems obvious, no experimental evidence has yet been presented. In this paper, using polarimetric synthetic aperture radar (POLSAR data acquired by Phased Array L-band SAR (PALSAR on board of Advanced Land Observing Satellite (ALOS, an experimental proof is presented to show that both algorithms indeed produce identical results.

  10. Ammonia-water mixtures at high pressures - Melting curves of ammonia dihydrate and ammonia monohydrate and a revised high-pressure phase diagram for the water-rich region. [in primordial solar system ices

    Science.gov (United States)

    Boone, S.; Nicol, M. F.

    1991-01-01

    The phase relations of some mixtures of ammonia and water are investigated to create a phase diagram in pressure-temperature-composition space relevant to the geophysical study of bodies in the outer solar system. The mixtures of NH3(x)H2O(1-x), where x is greater than 0.30 but less than 0.51, are examined at pressures and temperatures ranging from 0-6.5 GPa and 125-400 K, respectively. The ruby luminescence technique monitors the pressure and a diamond-anvil cell compresses the samples, and the phases are identified by means of normal- and polarized-light optical microscopy. The melting curve for NH3H2O(2) is described by the equation T = 176 + 60P - 8.5P squared for the ranges of 0.06-1.4 GPa and 179-243 K. The equation for NH3H2O is T = 194 + 37P - P squared, which represents a minor correction of a previous description by Johnson et al. (1985). Observed phase transitions are consistent with the high-pressure stability limit of NH3H2O(2), and the transition boundary is found to be linear.

  11. Is 67P/Churyumov-Gerasimenko a Classical JFC? Clues from Recent Polarimetric Observations

    Science.gov (United States)

    Hadamcik, Edith; Levasseur-Regourd, A.; Sen, A.; Gupta, R.; Lasue, J.

    2009-09-01

    Remote observations of the light scattered by comet 67P/Churyumov-Gerasimenko dust coma are of major importance to determine the physical properties of the particles and prepare the rendezvous with the ESA/Rosetta spacecraft in 2014. While dust observations have been made during different apparitions, polarization measurements were only obtained during the 1982 apparition by spectropolarimetry [1-2]. Recent imaging polarimetric observations were conducted at Haute-Provence observatory (France) on 2009 March 17-19 at 35 deg. phase angle and at IUCAA Girawali observatory (India) on 2008 December 25-27 at 36 deg. phase angle and on 2009 April 30-May 1 at 29 deg. phase angle. The imaging technique allows us to follow the intensity and polarization variations through the coma and their evolution. The decrease in intensity as a function of the distance to nucleus in log-log scale is close to -1 on average but important variations with values down to -1.5 are observed in agreement with previous observations in 1982-83 and 1995-96 [3]. Aperture polarization values are nominal before perihelion. Nevertheless, after perihelion, the increase in polarization suggests that an outburst occurred. Finally, comet 67P/C-G results will be compared to those obtained for other comets, including Jupiter Family Comets [4,5]. Polarization and intensity variations in the coma are reminiscent of those noticed for 9P/Tempel 1 (before Deep Impact) and comet C/2000 WM1 [5]. The presence of rather large particles can thus be suggested before and after perihelion. The properties of the particles ejected during post-perihelion will be discussed. [1] Myers and Nordsieck, Icarus 58, 431 (1984) [2] Levasseur-Regourd et al., The New Rosetta Targets, Kluwer, 111 (2004) [3] Schleicher, Icarus 181, 442 (2006) [4] Hadamcik and Levasseur-Regourd, PSS 57, 1118 (2009) [5] Hadamcik and Levasseur-Regourd, JQSRT, 79-80, 661 (2003)

  12. Modelling of adsorption kinetics and calibration curves of gaseous volatile organic compounds with adsorptive solid-phase microextraction fibre: toluene and acetone for indoor air applications.

    Science.gov (United States)

    Mocho, Pierre; Nicolle, Jérôme; Desauziers, Valérie

    2008-09-01

    Solid-phase microextraction (SPME) with adsorptive Carboxen/PDMS fibre is a powerful sampling device for volatile organic compounds (VOCs) at trace levels in air. However, owing to competitive adsorption, quantification remains a challenging task. In this area, a theoretical model, based on Fick's laws and an extended Langmuir equation, is proposed to deal with the adsorption kinetics of acetone/toluene mixture on SPME fibre under various static extraction conditions. The semipredictive model is first used to determine the axial diffusion coefficients of analytes in the sampling device. The model is then tested with a complex VOC mixture, showing good agreement with experimental data.

  13. Fiber-based polarimetric stress sensor for measuring the Young's modulus of biomaterials

    Science.gov (United States)

    Harrison, Mark C.; Armani, Andrea M.

    2015-03-01

    Polarimetric optical fiber-based stress and pressure sensors have proven to be a robust tool for measuring and detecting changes in the Young's modulus (E) of materials in response to external stimuli, including the real-time monitoring of the structural integrity of bridges and buildings. These sensors typically work by using a pair of polarizers before and after the sensing region of the fiber, and often require precise alignment to achieve high sensitivity. The ability to perform similar measurements in natural and in engineered biomaterials could provide significant insights and enable research advancement and preventative healthcare. However, in order for this approach to be successful, it is necessary to reduce the complexity of the system by removing free-space components and the need for alignment. As the first step in this path, we have developed a new route for performing these measurements. By generalizing and expanding established theoretical analyses for these types of sensors, we have developed a predictive theoretical model. Additionally, by replacing the conventional free space components and polarization filters with a polarimeter, we have constructed a sensor system with higher sensitivity and which is semi-portable. In initial experiments, a series of polydimethylsiloxane (PDMS) samples with several base:curing agent ratios ranging from 5:1 up to 30:1 were prepared to simulate tissues with different stiffnesses. By simultaneously producing stress-strain curves using a load frame and monitoring the polarization change of light traveling through the samples, we verified the accuracy of our theoretical model.

  14. Contractibility of curves

    Directory of Open Access Journals (Sweden)

    Janusz Charatonik

    1991-11-01

    Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.

  15. Space-filling Curves

    Indian Academy of Sciences (India)

    In this article some Peano curves are exhibited and some of their recent applications are dis- cussed. A C++ program to draw the Hilbert curve approximately is given. 1. Introduction. A 'continuous curve' in the plane is usually defined as the path traced by a moving point (x (t), Y (t)) as t runs over an interval of the real line, ...

  16. The Jordan Curve Theorem

    Indian Academy of Sciences (India)

    Institute, Calcutta. Apart from mathematics, he likes painting and reading. Unlike most others he dislikes computers. Ritabrata Munshi. Introduction. In this two-part article we will consider one of the classi- cal theorems of mathematics, the Jordan curve theorem. It states that a simple closed curve (i.e., a closed curve which.

  17. ECM using Edwards curves

    DEFF Research Database (Denmark)

    Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja

    2013-01-01

    This paper introduces EECM-MPFQ, a fast implementation of the elliptic-curve method of factoring integers. EECM-MPFQ uses fewer modular multiplications than the well-known GMP-ECM software, takes less time than GMP-ECM, and finds more primes than GMP-ECM. The main improvements above the modular......-arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...

  18. The Impact of Forest Density on Forest Height Inversion Modeling from Polarimetric InSAR Data

    Directory of Open Access Journals (Sweden)

    Changcheng Wang

    2016-03-01

    Full Text Available Forest height is of great significance in analyzing the carbon cycle on a global or a local scale and in reconstructing the accurate forest underlying terrain. Major algorithms for estimating forest height, such as the three-stage inversion process, are depending on the random-volume-over-ground (RVoG model. However, the RVoG model is characterized by a lot of parameters, which influence its applicability in forest height retrieval. Forest density, as an important biophysical parameter, is one of those main influencing factors. However, its influence to the RVoG model has been ignored in relating researches. For this paper, we study the applicability of the RVoG model in forest height retrieval with different forest densities, using the simulated and real Polarimetric Interferometric SAR data. P-band ESAR datasets of the European Space Agency (ESA BioSAR 2008 campaign were selected for experiments. The test site was located in Krycklan River catchment in Northern Sweden. The experimental results show that the forest density clearly affects the inversion accuracy of forest height and ground phase. For the four selected forest stands, with the density increasing from 633 to 1827 stems/Ha, the RMSEs of inversion decrease from 4.6 m to 3.1 m. The RVoG model is not quite applicable for forest height retrieval especially in sparsely vegetated areas. We conclude that the forest stand density is positively related to the estimation accuracy of the ground phase, but negatively correlates to the ground-to-volume scattering ratio.

  19. Application of Deep Networks to Oil Spill Detection Using Polarimetric Synthetic Aperture Radar Images

    Directory of Open Access Journals (Sweden)

    Guandong Chen

    2017-09-01

    Full Text Available Polarimetric synthetic aperture radar (SAR remote sensing provides an outstanding tool in oil spill detection and classification, for its advantages in distinguishing mineral oil and biogenic lookalikes. Various features can be extracted from polarimetric SAR data. The large number and correlated nature of polarimetric SAR features make the selection and optimization of these features impact on the performance of oil spill classification algorithms. In this paper, deep learning algorithms such as the stacked autoencoder (SAE and deep belief network (DBN are applied to optimize the polarimetric feature sets and reduce the feature dimension through layer-wise unsupervised pre-training. An experiment was conducted on RADARSAT-2 quad-polarimetric SAR image acquired during the Norwegian oil-on-water exercise of 2011, in which verified mineral, emulsions, and biogenic slicks were analyzed. The results show that oil spill classification achieved by deep networks outperformed both support vector machine (SVM and traditional artificial neural networks (ANN with similar parameter settings, especially when the number of training data samples is limited.

  20. Fitting a Two-Component Scattering Model to Polarimetric SAR Data

    Science.gov (United States)

    Freeman, A.

    1998-01-01

    Classification, decomposition and modeling of polarimetric SAR data has received a great deal of attention in the recent literature. The objective behind these efforts is to better understand the scattering mechanisms which give rise to the polarimetric signatures seen in SAR image data. In this Paper an approach is described, which involves the fit of a combination of two simple scattering mechanisms to polarimetric SAR observations. The mechanisms am canopy scatter from a cloud of randomly oriented oblate spheroids, and a ground scatter term, which can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, seen through a layer of vertically oriented scatterers. An advantage of this model fit approach is that the scattering contributions from the two basic scattering mechanisms can be estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. The model fit can be applied to polarimetric AIRSAR data at C-, L- and P-Band.

  1. Evaluation of Polarimetric SAR Decomposition for Classifying Wetland Vegetation Types

    Directory of Open Access Journals (Sweden)

    Sang-Hoon Hong

    2015-07-01

    Full Text Available The Florida Everglades is the largest subtropical wetland system in the United States and, as with subtropical and tropical wetlands elsewhere, has been threatened by severe environmental stresses. It is very important to monitor such wetlands to inform management on the status of these fragile ecosystems. This study aims to examine the applicability of TerraSAR-X quadruple polarimetric (quad-pol synthetic aperture radar (PolSAR data for classifying wetland vegetation in the Everglades. We processed quad-pol data using the Hong & Wdowinski four-component decomposition, which accounts for double bounce scattering in the cross-polarization signal. The calculated decomposition images consist of four scattering mechanisms (single, co- and cross-pol double, and volume scattering. We applied an object-oriented image analysis approach to classify vegetation types with the decomposition results. We also used a high-resolution multispectral optical RapidEye image to compare statistics and classification results with Synthetic Aperture Radar (SAR observations. The calculated classification accuracy was higher than 85%, suggesting that the TerraSAR-X quad-pol SAR signal had a high potential for distinguishing different vegetation types. Scattering components from SAR acquisition were particularly advantageous for classifying mangroves along tidal channels. We conclude that the typical scattering behaviors from model-based decomposition are useful for discriminating among different wetland vegetation types.

  2. Polarimetric study of the interstellar medium in Taurus Dark Clouds

    International Nuclear Information System (INIS)

    Hsu, J.

    1985-01-01

    An optical linear polarimetric survey was completed for more than 300 stars in an area of 6.5 0 x 10 0 toward the Taurus Dark Clouds Complex. It was found that the orientation of the magnetic field is roughly perpendicular to the elongation direction of the dust lanes, indicating cloud contraction along the magnetic field lines. The distance to the front edge of the dark clouds in Taurus is determined to be 126 pc. There is only insignificant amount of obscuring material between the cloud complex and the Sun. Besides the polarization data, the reddenings of about 250 stars were also obtained from the UBV photometry. The mean polarization to reddening ratio in the Taurus region is 4.6, which is similar to that of the general interstellar matter. The wavelengths of maximum polarization were determined for 30 stars in Taurus. They show an average value of lambda/sub max/ = 0.57 μm, which is only slightly higher than the mean value of the general interstellar medium, lambda/sub max/ = 0.55 μm. A few stars that show higher values of lambda/sub max/ are found near the small isolated regions of very high extinction. One such highly obscured small region where very complex long chain molecules have been discovered in the ratio spectra, is the Taurus Molecular Cloud 1

  3. Sample Extraction Bsaed on Helix Scattering for Polarimetric SAR Calibratio

    Science.gov (United States)

    Chang, Y.; Yang, J.; Li, P.; Zhao, L.; Shi, L.

    2017-09-01

    Polarimetric calibration (PolCAL) of Synthetic Aperture Radar (SAR) images is a significant preprocessing for further applications. Since the reflection symmetry property of distributed objects can provide stable constraints for PolCAL. It is reasonable to extract these reference samples before calibration. The helix scattering generally appears in complex urban area and disappears for a natural scatterer, making it a good measure to extract distributed objects. In this paper, a novel technique that extracts reflecting symmetry samples is proposed by using helix scattering. The helix scattering information is calculated by Yamaguchi four-component decomposition algorithm. An adaptive threshold selection algorithm based on generalized Gaussian distribution is also utilized to scale the helix scattering components automatically, getting rid of the problem of various numerical range. The extracting results will be taken as PolCAL reference samples and the Quegan method are utilized to calibrate these PolSAR images. A C-band airborne PolSAR data was taken as examples to evaluate its ability in improving calibration precision. Traditional method i.e. extracting samples with span power was also evaluated as contrast experiment. The results showed that the samples extracting method based on helix scattering can improve the Polcal precision preferably.

  4. SAMPLE EXTRACTION BSAED ON HELIX SCATTERING FOR POLARIMETRIC SAR CALIBRATIO

    Directory of Open Access Journals (Sweden)

    Y. Chang

    2017-09-01

    Full Text Available Polarimetric calibration (PolCAL of Synthetic Aperture Radar (SAR images is a significant preprocessing for further applications. Since the reflection symmetry property of distributed objects can provide stable constraints for PolCAL. It is reasonable to extract these reference samples before calibration. The helix scattering generally appears in complex urban area and disappears for a natural scatterer, making it a good measure to extract distributed objects. In this paper, a novel technique that extracts reflecting symmetry samples is proposed by using helix scattering. The helix scattering information is calculated by Yamaguchi four-component decomposition algorithm. An adaptive threshold selection algorithm based on generalized Gaussian distribution is also utilized to scale the helix scattering components automatically, getting rid of the problem of various numerical range. The extracting results will be taken as PolCAL reference samples and the Quegan method are utilized to calibrate these PolSAR images. A C-band airborne PolSAR data was taken as examples to evaluate its ability in improving calibration precision. Traditional method i.e. extracting samples with span power was also evaluated as contrast experiment. The results showed that the samples extracting method based on helix scattering can improve the Polcal precision preferably.

  5. Modeling the photo-polarimetric characteristics of brown dwarfs

    Science.gov (United States)

    Sanghavi, Suniti; Millar-Blanchaer, Max; Jensen-Clem, Rebecca; Shporer, Avi; Nilsson, Ricky; Tinyanont, Samaporn; Riedel, Adric; Kataria, Tiffany; Mawet, Dimitri

    2018-01-01

    An envelope of scatterers like free electrons, atoms/molecules, or haze/clouds affect the Stokes vector of radiation emitted by an oblate body.Due to their high rotation rates, brown dwarfs (BDs) are often considerably oblate. We present a conics-based radiative transfer (RT) scheme for computing the disc-resolved and disc-integrated polarized emission of an oblate body like a BD or extrasolar giant planet (EGP) bearing homogenous or patchy clouds. Using this capability, we theoretically examine the photo-polarimetric signal of BDs as a function of the scattering properties of its atmosphere like cloud optical thickness and grain size concurrently with BD properties like oblateness and inclination angle. The effect of oblateness is examined with and without the temperature gradients caused by gravitational darkening, revealing that the latter can considerably amplify the disc-integrated polarization. The signal depends on both oblateness and inclination angle, with the degree of polarization (DoP) increasing with oblateness and decreasing with inclination, a property useful for assessing the exact spatial orientation of the rotation axis in favorable cases. Our examination of BD cloud properties shows a relative blue-shift in the near-infrared (NIR) for increasing droplet size in optically thick clouds - interesting in view of the observed relative brightening in the J-band for L/T transition BDs. For large cloud grains, the polarization decreases sharply, while the transmitted intensity shows a steady increase, thus reducing the DoP.

  6. Detecting the Depth of a Subsurface Brine Layer in Lop Nur Lake Basin Using Polarimetric L-Band SAR

    Directory of Open Access Journals (Sweden)

    Chang-An Liu

    2015-01-01

    Full Text Available Lop Nur once was a huge lake located in northwestern China. At present, there is no surface water in Lop Nur Lake basin and on SAR images it looks like an “Ear.” The objective of this paper is to retrieve the depth of subsurface brine layer in Lop Nur by copolarized phase difference of surface scattering. Based on field investigation and analysis of sample properties, a two-layer scattering structure was proposed with detailed explanations of scattering mechanisms. The relationship between copolarized phase difference and the brine layer depth in the region of Lop Nur were studied. The copolarized phase difference of surface scattering was extracted by model-based polarimetric decomposition method. A good linear correlation between measured subsurface brine layer depth and copolarized phase difference with R2 reaching 0.82 was found. Furthermore, the subsurface brine layer depth of the entire lake area was analyzed. According to the retrieved maps, some interesting phenomena were found, and several hypotheses about the past water withdrawal process and the environmental evolution had been proposed to theoretically explain these phenomena. Based on the penetration capability of SAR the reconstruction of historical evolution process of Lop Nur will be an interesting topic for future research.

  7. Forest Structure Characterization Using Jpl's UAVSAR Multi-Baseline Polarimetric SAR Interferometry and Tomography

    Science.gov (United States)

    Neumann, Maxim; Hensley, Scott; Lavalle, Marco; Ahmed, Razi

    2013-01-01

    This paper concerns forest remote sensing using JPL's multi-baseline polarimetric interferometric UAVSAR data. It presents exemplary results and analyzes the possibilities and limitations of using SAR Tomography and Polarimetric SAR Interferometry (PolInSAR) techniques for the estimation of forest structure. Performance and error indicators for the applicability and reliability of the used multi-baseline (MB) multi-temporal (MT) PolInSAR random volume over ground (RVoG) model are discussed. Experimental results are presented based on JPL's L-band repeat-pass polarimetric interferometric UAVSAR data over temperate and tropical forest biomes in the Harvard Forest, Massachusetts, and in the La Amistad Park, Panama and Costa Rica. The results are partially compared with ground field measurements and with air-borne LVIS lidar data.

  8. Estimation and Removing of Anisotropic Scattering for Multiaspect Polarimetric SAR Image

    Directory of Open Access Journals (Sweden)

    Li Yang

    2015-06-01

    Full Text Available Multiaspect Synthetic Aperture Radar (SAR can generate high resolution images and target scattering signatures in different azimuth angles from the coherent integration of all subaperture images. However, mixed anisotropic scatters limit the application of traditional imaging theory. Anisotropic scattering may introduce errors in polarimetric parameters by decreasing the reliability of terrain classification and detection of variability. Thus a method is proposed for estimating and removing anisotropic scattering in multiaspect polarimetric SAR images. The proposed algorithm is based on the maximum likelihood and likelihood-ratio tests for the two-class case, while considering the speckle effect, the mechanism of removing the anisotropic scattering, and the monotonicity of the Constant False Alarm Rate (CFAR detection function. We compare the polarimetric entropy before and after removing the anisotropic subapertures, and then validate the algorithm's potential in retrieving the target signature using a P-band quad-pol airborne SAR with circular trajectory.

  9. Fast polarimetric dehazing method for visibility enhancement in HSI colour space

    Science.gov (United States)

    Zhang, Wenfei; Liang, Jian; Ren, Liyong; Ju, Haijuan; Bai, Zhaofeng; Wu, Zhaoxin

    2017-09-01

    Image haze removal has attracted much attention in optics and computer vision fields in recent years due to its wide applications. In particular, the fast and real-time dehazing methods are of significance. In this paper, we propose a fast dehazing method in hue, saturation and intensity colour space based on the polarimetric imaging technique. We implement the polarimetric dehazing method in the intensity channel, and the colour distortion of the image is corrected using the white patch retinex method. This method not only reserves the detailed information restoration capacity, but also improves the efficiency of the polarimetric dehazing method. Comparison studies with state of the art methods demonstrate that the proposed method obtains equal or better quality results and moreover the implementation is much faster. The proposed method is promising in real-time image haze removal and video haze removal applications.

  10. The Potential of Polarimetric and Compact SAR Data in Rice Identification

    International Nuclear Information System (INIS)

    Shao, Y; Li, K; Liu, L; Yang, Z; Brisco, B

    2014-01-01

    Rice is a major food staple in the world, and provides food for more than one-third of the global population. The monitoring and mapping of paddy rice in a timely and efficient manner is very important for governments and decision makers. Synthetic Aperture Radar (SAR) has been proved to be a significant data source in rice monitoring. In this study, RADARSAT-2 polarimetric data were used to simulate compact polarimetry data. The simulated compact data and polarimetric data were then used to evaluate the information content for rice identification. The results indicate that polarimetric SAR can be used for rice identification based on the scattering mechanisms. The compact polarization RH and the RH/RL ratio are very promising for the discrimination of transplanted rice and direct-sown rice. These results require verification in further research

  11. Polarimetric SAR Image Classification Using Multiple-feature Fusion and Ensemble Learning

    Directory of Open Access Journals (Sweden)

    Sun Xun

    2016-12-01

    Full Text Available In this paper, we propose a supervised classification algorithm for Polarimetric Synthetic Aperture Radar (PolSAR images using multiple-feature fusion and ensemble learning. First, we extract different polarimetric features, including extended polarimetric feature space, Hoekman, Huynen, H/alpha/A, and fourcomponent scattering features of PolSAR images. Next, we randomly select two types of features each time from all feature sets to guarantee the reliability and diversity of later ensembles and use a support vector machine as the basic classifier for predicting classification results. Finally, we concatenate all prediction probabilities of basic classifiers as the final feature representation and employ the random forest method to obtain final classification results. Experimental results at the pixel and region levels show the effectiveness of the proposed algorithm.

  12. A high resolution polarimetric L-band SAR-design and first results

    DEFF Research Database (Denmark)

    Skou, Niels; Granholm, Johan; Woelders, Kim

    1995-01-01

    An L-band polarimetric SAR system has been developed as part of the dual frequency (L- and C-band), polarimetric, airborne EMISAR system. The SAR features a unique combination of fine resolution (2×2 m) and wide swath (9.3 km). The transmitter power is 6 kW. From a flight altitude of 41,000 ft...... conventional PIN diode switch matrix able to sustain the 6 kW peak power from the transmitter still exhibiting low loss (0.3 dB) and high isolation (more than 50 dB). Thus system cross talk (between polarizations) is dominated by antenna cross talk and is some -35 dB. Polarimetric imagery has been acquired...

  13. Contribution of polarimetric imaging for the characterization of fibrous surface properties at different scales

    Science.gov (United States)

    Tourlonias, Michel; Bigué, Laurent; Bueno, Marie-Ange

    2010-01-01

    The point in using polarimetric imaging for surface characterization is highlighted in this paper. A method for the evaluation of nonwoven surface properties at microscopic and macroscopic scales is described. This method is based on a polarimetric apparatus and various image processing operations are then performed depending on the studied scale. Polarimetric imaging applied to nonwovens, particularly degree of polarization imaging, highlights texture inhomogeneities. At both scales, image processing techniques were designed to analyze surface zones of different textures. At the macroscopic scale, a basic image processing was developed in order to detect the nonwoven manufacturing process defects. Moreover at the microscopic scale, i.e. at the fiber scale, image processing was adapted to evaluate fiber orientation within nonwovens, which is known to be an important information for mechanical behavior prediction.

  14. Detection of buried pipes by polarimetric borehole radar; Polarimetric borehole radar ni yoru maisetsukan no kenshutsu jikken

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Niitsuma, H. [Tohoku University, Sendai (Japan); Nakauchi, T. [Osaka Gas Co. Ltd., Osaka (Japan)

    1997-05-27

    If the borehole radar is utilized for detection of buried pipes, the underground radar measurement becomes possible even in the situation where the mesurement on the earth surface is difficult, for example, such a place as under the road where there is much traffic. However, since buried pipes are horizontally installed and the existing borehole radar can send/receive only vertical polarization, the measurement conducted comes to be poor in efficiency from a viewpoint of the polarization utilization. Therefore, by introducing the polarimetric borehole radar to the detection of buried pipes, a basic experiment was conducted for the effective detection of horizontal buried pipes. Proposing the use of a slot antenna which can send/receive horizontal polarization in borehole in addition to a dipole antenna which sends/receives vertical polarization, developed was a step frequency type continuous wave radar of a network analyzer basis. As a result of the experiment, it was confirmed that reflection from buried pipes is largely dependent on polarization. Especially, it was found that in the slot dipole cross polarization mesurement, reflection from buried pipes can be emphasized. 4 refs., 5 figs.

  15. Design and Calibration of the PHARUS Polarimetric Airborne SAR

    NARCIS (Netherlands)

    Snoeij, P.; Hoogeboom, P.; Koomen, P.J.; Vermeulen, B.C.B.; Pouwels, H.

    1996-01-01

    The PHARUS system uses a phased array antenna with solid state amplifiers. The project consisted of two phases, a definition phase and a realization phase. The definition phase consisted of the actual realization of a SAR research system called PHARS, which made its first successful testflight in

  16. Complex Wishart distribution based analysis of polarimetric synthetic aperture radar data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Skriver, Henning; Conradsen, Knut

    2007-01-01

    Multi-look, polarimetric synthetic aperture radar (SAR) data are often worked with in the so-called covariance matrix representation. For each pixel this representation gives a 3x3 Hermitian, positive definite matrix which follows a complex Wishart distribution. Based on this distribution a test ...... covering agricultural fields near Foulum, Denmark, are used. Soon the Japanese ALOS, the German TerraSAR-X and the Canadian RADARSAT-2 will acquire space-borne, polarimetric data making analysis based on these methods important....

  17. Comparison between Multitemporal and Polarimetric SAR Data for Land Cover Classification

    DEFF Research Database (Denmark)

    Skriver, Henning

    2008-01-01

    The investigation focuses on the determination of the land cover type using SAR data, including single polarisation, dual polarisation and fully polarimetric data, at L-band. The analysed data set was acquired during the AgriSAR 2006 campaign by the airborne ESAR system over the Gormin agricultural...... site (Northeast Germany). The multitemporal acquisitions significantly improve the classification results for single and dual polarization configurations. The best results for the single and dual polarization configurations are better than for the polarimetric mode. Overall, the cross...

  18. OPTICAL PHOTOMETRIC AND POLARIMETRIC INVESTIGATION OF NGC 1931

    International Nuclear Information System (INIS)

    Pandey, A. K.; Eswaraiah, C.; Sharma, Saurabh; Yadav, Ram Kesh; Samal, M. R.; Chauhan, N.; Chen, W. P.; Jose, J.; Ojha, D. K.; Chandola, H. C.

    2013-01-01

    We present optical photometric and polarimetric observations of stars toward NGC 1931 with the aim of deriving cluster parameters such as distance, reddening, age, and luminosity/mass function as well as understanding dust properties and star formation in the region. The distance to the cluster is found to be 2.3 ± 0.3 kpc and the reddening E(B – V) in the region is found to be variable. The stellar density contours reveal two clusters in the region. The observations suggest a differing reddening law within the cluster region. Polarization efficiency of the dust grains toward the direction of the cluster is found to be less than that for the general diffuse interstellar medium (ISM). The slope of the mass function (–0.98 ± 0.22) in the southern region in the mass range of 0.8 ☉ < 9.8 is found to be shallower in comparison to that in the northern region (–1.26 ± 0.23), which is comparable to the Salpeter value (–1.35). The K-band luminosity function (KLF) of the region is found to be comparable to the average value of the slope (∼0.4) for young clusters obtained by Lada and Lada; however, the slope of the KLF is steeper in the northern region as compared to the southern region. The region is probably ionized by two B2 main-sequence-type stars. The mean age of the young stellar objects (YSOs) is found to be 2 ± 1 Myr, which suggests that the identified YSOs could be younger than the ionizing sources of the region. The morphology of the region, the distribution and ages of the YSOs, and ionizing sources indicate a triggered star formation in the region.

  19. Microphysical Structures of Hurricane Irma Observed by Polarimetric Radar

    Science.gov (United States)

    Didlake, A. C.; Kumjian, M. R.

    2017-12-01

    This study examines dual-polarization radar observations of Hurricane Irma as its center passed near the WSR-88D radar in Puerto Rico, capturing needed microphysical information of a mature tropical cyclone. Twenty hours of observations continuously sampled the inner core precipitation features. These data were analyzed by annuli and azimuth, providing a bulk characterization of the primary eyewall, secondary eyewall, and rainbands as they varied around the storm. Polarimetric radar variables displayed distinct signatures of convective and stratiform precipitation in the primary eyewall and rainbands that were organized in a manner consistent with the expected kinematic asymmetry of a storm in weak environmental wind shear but with moderate low-level storm-relative flow. In the front quadrants of the primary eyewall, vertical profiles of differential reflectivity (ZDR) exhibit increasing values with decreasing height consistent with convective precipitation processes. In particular, the front-right quadrant exhibits a signature in reflectivity (ZH) and ZDR indicating larger, sparser drops, which is consistent with a stronger updraft present in this quadrant. In the rear quadrants, a sharply peaked ZDR maximum occurs within the melting layer, which is attributed of stratiform processes. In the rainbands, the convective to stratiform transition can be seen traveling from the front-right to the front-left quadrant. The front-right quadrant exhibits lower co-polar correlation coefficient (ρHV) values in the 3-8 km altitude layer, suggesting larger vertical spreading of various hydrometeors that occurs in convective vertical motions. The front-left quadrant exhibits larger ρHV values, suggesting less diversity of hydrometeor shapes, consistent with stratiform processes. The secondary eyewall did not exhibit a clear signature of processes preferred in a specific quadrant, and a temporal analysis of the secondary eyewall revealed a complex evolution of its structure

  20. Laboratory Measurements of Single-Particle Polarimetric Spectrum

    Science.gov (United States)

    Gritsevich, M.; Penttila, A.; Maconi, G.; Kassamakov, I.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

    2017-12-01

    Measuring scattering properties of different targets is important for material characterization, remote sensing applications, and for verifying theoretical results. Furthermore, there are usually simplifications made when we model targets and compute the scattering properties, e.g., ideal shape or constant optical parameters throughout the target material. Experimental studies help in understanding the link between the observed properties and computed results. Experimentally derived Mueller matrices of studied particles can be used as input for larger-scale scattering simulations, e.g., radiative transfer computations. This method allows to bypass the problem of using an idealized model for single-particle optical properties. While existing approaches offer ensemble- and orientation-averaged particle properties, our aim is to measure individual particles with controlled or known orientation. With the newly developed scatterometer, we aim to offer novel possibility to measure single, small (down to μm-scale) targets and their polarimetric spectra. This work presents an experimental setup that measures light scattered by a fixed small particle with dimensions ranging between micrometer and millimeter sizes. The goal of our setup is nondestructive characterization of such particles by measuring light of multiple wavelengths scattered in 360° in a horizontal plane by an ultrasonically levitating sample, whilst simultaneously controlling its 3D position and orientation. We describe the principles and design of our instrument and its calibration. We also present example measurements of real samples. This study was conducted under the support from the European Research Council, in the frame of the Advanced Grant project No. 320773 `Scattering and Absorption of Electromagnetic Waves in Particulate Media' (SAEMPL).

  1. OIL DETECTION IN A COASTAL MARSH WITH POLARIMETRIC SAR

    Directory of Open Access Journals (Sweden)

    E. Ramsey III

    2012-09-01

    Full Text Available The NASA UAVSAR was deployed June 2010 to support Deep Water Horizon oil spill response activities specifically, oil detection and characterization, oil extent mapping in wetlands, coastal resource impact detection, and ecosystem recovery. The UAVSAR platform demonstrated enhanced capability to act rapidly and provide targeted mapping response. Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band Synthetic Aperture Radar (PolSAR for mapping oil in wetlands, specifically within Barataria Bay in eastern coastal Louisiana. Barataria Bay contained a numerous site observations confirming spatially extensive shoreline oil impacts, multiple oil spill UAVSAR collections, and a near anniversary 2009 collection. PolSAR oil detection relied on decomposition and subsequent classifications of the single look complex (SLC calibrated radar cross sections representing the complex elements of the scattering matrix. Initial analyses results found that shoreline marsh structural damage as well as oil on marsh plants and sediments without canopy structural damage were exhibited as anomalous features on post-spill SLC scenes but were not evident on the pre-spill SLC scene collected in 2009. Pre-spill and post-spill Freeman-Durden (FD and Cloude-Pottier (CP decompositions and the Wishart classifications seeded with the FD and CP classes (Wishart-FD also highlighted these nearshore features as a change in dominate scatter from pre-spill to post-spill. SLC analyses also indicated penetration of oil ladened waters into interior marshes well past the immediate shorelines; however, these post-spill SLC analyses results could not be validated due to the lack of observational data and possible flooding in the pre-spill SLC scene.

  2. Space-filling Curves

    Indian Academy of Sciences (India)

    mathematics and computer applications for the last 20 years. He has been a National Science. Talent awardee of. NCERT in mathematics. GENERAL I ARTICLE. Space-filling Curves. ReMittal. In this article some Peano curves are exhibited and some of their recent applications are dis- cussed. A C++ program to draw the ...

  3. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  4. Tempo curves considered harmful

    NARCIS (Netherlands)

    Desain, P.; Honing, H.

    1993-01-01

    In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression

  5. Power Curve Measurements REWS

    DEFF Research Database (Denmark)

    Federici, Paolo; Georgieva Yankova, Ginka

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to a draft of IEC 61400-12-1 Ed.2.......The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to a draft of IEC 61400-12-1 Ed.2....

  6. GEOMETRIC PROGRESSIONS ON ELLIPTIC CURVES.

    Science.gov (United States)

    Ciss, Abdoul Aziz; Moody, Dustin

    2017-01-01

    In this paper, we look at long geometric progressions on different model of elliptic curves, namely Weierstrass curves, Edwards and twisted Edwards curves, Huff curves and general quartics curves. By a geometric progression on an elliptic curve, we mean the existence of rational points on the curve whose x -coordinate (or y -coordinate) are in geometric progression. We find infinite families of twisted Edwards curves and Huff curves with geometric progressions of length 5, an infinite family of Weierstrass curves with 8 term progressions, as well as infinite families of quartic curves containing 10-term geometric progressions.

  7. Limiting Temperatures, Caloric Curves and Phase Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Hagel, K.; Ma, Y.; Murray, M.; Natowitz, J.; Wada, R.; Kowalski, S.; Materna, T.; Keksis, A.; Makeev, A.; Martin, E.; Qin, L.; Veselsky, M.; Ruangma, A.; Shetty, D.V.; Souliotis, G.; Winchester, E.M.; Yennello, S.J. [Cyclotron Institute, TAMU, College Station (TX) (United States); Cinausero, M.; Prete, E.G.; Fioretton, E. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Fabris, D.; Lunardon, M.; Nebbia, G.; Rizzi, V.; Viesti, G. [INFN and Dipartimento di Fisica dell' Universita di Padova, Padova (Italy); Majka, Z.; Cibor, J.; Staszel, P. [Jagellonian University, M Smoluchowski Institute of Physics, Krakow (Poland); Martinez-Davalos, R.A.; Menchaca-Rocha, A.; Alfarro, R. [Instituto de Fisica, UNAM, Mexico City (Mexico); Keutgen, T.; El Masri, Y. [Universite Catholique de Louvain, FNRS and IPN, Louvain-Neuve (Belgium)

    2003-07-01

    A status report on some experiments designed to probe the dynamic evolution, the degree of equilibration and disassembly modes of hot composite nuclei produced in Fermi energy heavy ion collisions is presented. (authors)

  8. On the Quaternionic Focal Curves

    Directory of Open Access Journals (Sweden)

    Nurten (BAYRAK GÜRSES

    2017-06-01

    Full Text Available In this study, a brief summary about quaternions and quaternionic curves are firstly presented. Also, the definition of focal curve is given. The focal curve of a smooth curve consists of the centers of its osculating hypersphere.  By using this definition and the quaternionic osculating hyperspheres of these curves, the quaternionic focal curves in the spaces $\\Q$ and $\\Q_\

  9. Learning Curve? Which One?

    Directory of Open Access Journals (Sweden)

    Paulo Prochno

    2004-07-01

    Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.

  10. Polarimetric borehole radar measurement near Nojima fault and its application to subsurface crack characterization; Polarimetric borehole radar ni yoru Nojima danso shuhen no chika kiretsu keisoku jikken

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Taniguchi, Y.; Miwa, T.; Niitsuma, H. [Tohoku University, Sendai (Japan); Ikeda, R. [National Research Institute for Disaster Prevention, Tsukuba (Japan); Makino, K. [Geophysical Surveying and Consulting Co. Ltd., Tokyo (Japan)

    1997-05-27

    Practical application of subsurface crack characterization by the borehole radar measurement to which the radar polarimetric method was introduced was attempted to measuring objects for which the borehole radar has not been much used, for example, the inside of low loss rock mass or fracture zone where cracks tightly exist. A system was trially manufactured which makes the radar polarimetric measurement possible in the borehole at a 1000m depth and with a about 10cm diameter, and a field experiment was conducted for realizing the subsurface crack characterization near the Nojima fault. For the measuring experiment by the polarimetric borehole radar, used were Iwaya borehole and Hirabayashi borehole drilled in the north of Awaji-shima, Hyogo-ken. In a comparison of both polarization systems of Hirabayashi borehole, reflected waves at depths of 1038m and 1047m are relatively stronger in both polarization systems than those with the same polarization form and at different depths, whereas reflected waves around a 1017m depth are strong only as to the parallel polarization system. Characteristics of the polarization in this experiment indirectly reflect crack structures. 6 refs., 6 figs., 1 tab.

  11. Evolution of microphysical structure of a subtropical squall line observed by a polarimetric radar and a disdrometer during OPACC in Eastern China

    Science.gov (United States)

    Wen, Jing; Zhao, Kun; Huang, Hao; Zhou, Bowen; Yang, Zhonglin; Chen, Gang; Wang, Mingjun; Wen, Long; Dai, Huaning; Xu, Lili; Liu, Su; Zhang, Guifu; Lee, Wen-Chau

    2017-08-01

    The evolution of the microphysical structures of a subtropical squall line observed during the Observation, Prediction and Analysis of Severe Convection of China (OPACC) field campaign in Eastern China is documented in this paper. The data collected from a C-band, polarimetric Doppler radar (reflectivity Z, differential reflectivity ZDR, and specific differential phase KDP) and a disdrometer are used to investigate the variations of microphysical characteristics within the convective region during the formative, intensifying, and mature stages of the squall line. The microphysical characteristics of the squall line are noticeably different among these three stages. When the squall line develops from the formative stage to the mature stage, its radar-derived drop size distribution (DSD) in the convective region evolves from continental-like convection to more maritime-like convection. Contrary to previous studies, the DSD characteristics of a convective line may not be simply locked to a geographical location but varied extensively throughout its life cycle. The polarimetric radar-derived liquid water content below the freezing level in the convective region is 3 times higher than the ice water content above the freezing level. This, in conjunction with a low cloud base ( 0.68 km) and a high freezing level ( 5 km), indicates a deep warm cloud layer and the dominance of the warm rain process within this squall line.

  12. Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

    Directory of Open Access Journals (Sweden)

    Laode M Golok Jaya

    2017-07-01

    Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

  13. Discrimination of Oil Slicks and Lookalikes in Polarimetric SAR Images Using CNN.

    Science.gov (United States)

    Guo, Hao; Wu, Danni; An, Jubai

    2017-08-09

    Oil slicks and lookalikes (e.g., plant oil and oil emulsion) all appear as dark areas in polarimetric Synthetic Aperture Radar (SAR) images and are highly heterogeneous, so it is very difficult to use a single feature that can allow classification of dark objects in polarimetric SAR images as oil slicks or lookalikes. We established multi-feature fusion to support the discrimination of oil slicks and lookalikes. In the paper, simple discrimination analysis is used to rationalize a preferred features subset. The features analyzed include entropy, alpha, and Single-bounce Eigenvalue Relative Difference (SERD) in the C-band polarimetric mode. We also propose a novel SAR image discrimination method for oil slicks and lookalikes based on Convolutional Neural Network (CNN). The regions of interest are selected as the training and testing samples for CNN on the three kinds of polarimetric feature images. The proposed method is applied to a training data set of 5400 samples, including 1800 crude oil, 1800 plant oil, and 1800 oil emulsion samples. In the end, the effectiveness of the method is demonstrated through the analysis of some experimental results. The classification accuracy obtained using 900 samples of test data is 91.33%. It is here observed that the proposed method not only can accurately identify the dark spots on SAR images but also verify the ability of the proposed algorithm to classify unstructured features.

  14. Wind direction over the ocean determined by an airborne, imaging, polarimetric radiometer system

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    2001-01-01

    The speed and direction of winds over the ocean can be determined by polarimetric radiometers. This has been established by theoretical work and demonstrated experimentally using airborne radiometers carrying out circle flights and thus measuring the full 360° azimuthal response from the sea surf...

  15. Detection and Monitoring of Inundation with Polarimetric L-Band SAR

    Science.gov (United States)

    Chapman, B. D.; Celi, J. E.; Hamilton, S. K.; McDonald, K. C.

    2014-12-01

    It has been known for decades that at wavelengths L-band or longer, SAR is a sensitive indicator of inundation underneath forest canopies. The high resolution detection of below-canopy inundation is difficult to accomplish at regional to continental scales using other types of remote sensing sensors, making it a compelling SAR measurement especially useful for studying wetland inundation dynamics, particularly in difficult-to-reach access, canopy-covered tropical forest environments. Most results have utilized spaceborne SAR observations with less than fully polarimetric data. Since one of the objectives of the NISAR mission is to characterize and understand the fundamental process that drives changes to ecosystems such as wetland inundated areas, we will discuss the sensitivity of L-band SAR to inundation. We will illustrate the detection of inundation using fully polarimetric L-band SAR data from UAVSAR, NASA's airborne SAR, over a tropical forest region in Ecuador and Peru. At the same time as the data collection, measurements were made on the ground to characterize vegetation and inundation characteristics. The field data were used to validate the results of classifying the vanZyl decomposition of the polarimetric data. We compare this classification with that possible with a reduced subset of the polarimetric observations.

  16. Polarimetric Determination of Starch in Raw Materials and Discharged Waste from Beer Production

    Directory of Open Access Journals (Sweden)

    Anca Farcas

    2013-11-01

    Full Text Available Brewer’s spent grain (BGS is a by-product of thebrewing process, consisting of the solid fraction of barley malt remainingafter separation of worth. In this research, raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method.

  17. The Solar Orbiter Mission and its Polarimetric and Helioseismic Imager (SO/PHI)

    Energy Technology Data Exchange (ETDEWEB)

    Gandorfer, Achim; Solanki, Sami K; Woch, Joachim [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany); Pillet, Valentin MartInez [Instituto de Astrofisica de Canarias, C/ VIa Lactea, s/n, E38205 - La Laguna (Tenerife) (Spain); Herrero, Alberto Alvarez [Instituto Nacional de Tecnica Aeroespacial, E-28850, Torrejon de Ardoz, Madrid (Spain); Appourchaux, Thierry, E-mail: gandorfer@mps.mpg.de [Institut d' Astrophysique Spatiale, CNRS-Universite Paris XI UMR8617, 91405 Orsay Cedex (France)

    2011-01-01

    We briefly outline the scientific and instrumental aspects of ESA's Solar Orbiter mission. Special emphasis is given to the Polarimetric and Helioseismic Imager, the instrument with the highest relevance for helioseismology applications, which will observe gas motions and the vector magnetic field in the photosphere at high spatial and temporal resolution.

  18. Applications of Polarimetric Radar to the Hydrometeorology of Urban Floods in St. Louis

    Science.gov (United States)

    Chaney, M. M.; Smith, J. A.; Baeck, M. L.

    2017-12-01

    Predicting and responding to flash flooding requires accurate spatial and temporal representation of rainfall rates. The polarimetric upgrade of all US radars has led to optimism about more accurate rainfall rate estimation from the NEXRAD network of WSR-88D radars in the US. Previous work has proposed different algorithms to do so, but significant uncertainties remain, especially for extreme short-term rainfall rates that control flash floods in urban settings. We will examine the relationship between radar rainfall estimates and gage rainfall rates for a catalog of 30 storms in St. Louis during the period of polarimetric radar measurements, 2012-2016. The storms are selected to provide a large sample of extreme rainfall measurements at the 15-minute to 3-hour time scale. A network of 100 rain gages and a lack of orographic or coastal effects make St. Louis an interesting location to study these relationships. A better understanding of the relationships between polarimetric radar measurements and gage rainfall rates will aid in refining polarimetric radar rainfall algorithms, in turn helping hydrometeorologists predict flash floods and other hazards associated with severe rainfall. Given the fact that St. Louis contains some of the flashiest watersheds in the United States (Smith and Smith, 2015), it is an especially important urban area in which to have accurate, real-time rainfall data. Smith, Brianne K, and James A Smith. "The Flashiest Watersheds in the Contiguous United States." American Meteorological Society (2015): 2365-2381. Web.

  19. Maritime target and sea clutter measurements with a coherent Doppler polarimetric surveillance radar

    NARCIS (Netherlands)

    Smith, A.J.E.; Gelsema, S.J.; Kester, L.J.H.M.; Melief, H.W.; Premel Cabic, G.; Theil, A.; Woudenberg, E.

    2002-01-01

    Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary

  20. Forest mapping using bi-aspect polarimetric SAR data in southwest China

    Science.gov (United States)

    Zhang, Fengli; Xu, Maosong; Xia, Zhongsheng; Wan, Zi; Li, Kun; Li, Xiaofang

    2009-10-01

    Synthetic aperture radar (SAR) provides a powerful tool for forestry inventory because of its all-weather and all-day capabilities. In this paper forest mapping method using bi-aspect polarimetric SAR data acquired from ascending and descending path has been studied. Zhazuo forest farm in Guizhou province was selected as test site and an 8-temporal field experiment was designed to obtain bio-physical parameters and spatial structure parameters of the 12 sample plots. Then the Michigan Microwave Canopy Scattering model (MIMICS) was employed to analyze the seasonal variation of these 4 types of managed forests. Using polarimetric Radarsat 2 data, scattering mechanisms of each forest type were determined and polarimetric variables were extracted and analyzed for forest discrimination. Considering the inherent geometric distortion of SAR imaging in hilly areas, a geometric correction strategy using bi-aspect SAR images and high resolution DEM was proposed. Then support vector machines method was adopted for classification of the whole test area. Experiments show that the bi-aspect geometric strategy is useful for hilly areas especially for shadow elimination in SAR image, and polarimetric SAR data is helpful to forest mapping.

  1. Airborn Ku-band polarimetric radar remote sensing of terrestrial snow cover

    Science.gov (United States)

    Simon H. Yueh; Steve J. Dinardo; Ahmed Akgiray; Richard West; Donald W. Cline; Kelly Elder

    2009-01-01

    Characteristics of the Ku-band polarimetric scatterometer (POLSCAT) data acquired from five sets of aircraft flights in the winter months of 2006-2008 for the second Cold Land Processes Experiment (CLPX-II) in Colorado are described in this paper. The data showed the response of the Ku-band radar echoes to snowpack changes for various types of background vegetation in...

  2. Feature level fusion of polarimetric infrared and GPR data for landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Jong, W. de; Schutte, K.; Yarovoy, A.G.; Kovalenko, V.; Bloemenkamp, R.F.

    2003-01-01

    Feature-level sensor fusion is the process where specific information (i.e. features) from objects detected by different sensors are combined and classified. This paper focuses on the feature-level fusion procedure for a sensor combination consisting of a polarimetric infrared (IR) imaging sensor

  3. Design of a Small, Low Cost, P-Band Airborne Polarimetric Synthetic Aperture Radar

    NARCIS (Netherlands)

    Figueras i Ventura, J.; Hoogeboom, P.

    2004-01-01

    A preliminary study of the design of a small, low cost, P-band airborne, polarimetric Synthetic Aperture Radar desired by the Wageningen University and the Borneo Orangutan Survival Foundation (BOS) to carry out forest biomass monitoring in Indonesia is presented. The requirements of the application

  4. Unsupervised polarimetric synthetic aperture radar image classification based on sketch map and adaptive Markov random field

    Science.gov (United States)

    Shi, Junfei; Li, Lingling; Liu, Fang; Jiao, Licheng; Liu, Hongying; Yang, Shuyuan; Liu, Lu; Hao, Hongxia

    2016-04-01

    Markov random field (MRF) model is an effective tool for polarimetric synthetic aperture radar (PolSAR) image classification. However, due to the lack of suitable contextual information in conventional MRF methods, there is usually a contradiction between edge preservation and region homogeneity in the classification result. To preserve edge details and obtain homogeneous regions simultaneously, an adaptive MRF framework is proposed based on a polarimetric sketch map. The polarimetric sketch map can provide the edge positions and edge directions in detail, which can guide the selection of neighborhood structures. Specifically, the polarimetric sketch map is extracted to partition a PolSAR image into structural and nonstructural parts, and then adaptive neighborhoods are learned for two parts. For structural areas, geometric weighted neighborhood structures are constructed to preserve image details. For nonstructural areas, the maximum homogeneous regions are obtained to improve the region homogeneity. Experiments are taken on both the simulated and real PolSAR data, and the experimental results illustrate that the proposed method can obtain better performance on both region homogeneity and edge preservation than the state-of-the-art methods.

  5. Polarimetric SAR Target Scattering Interpretation in Rotation Domain: Theory and Application

    Directory of Open Access Journals (Sweden)

    Chen Siwei

    2017-10-01

    Full Text Available Backscattering of radar targets is sensitive to the relative geometry between target orientations and the radar line of sight. This scattering diversity makes imaging radar represented by polarimetric Synthetic Aperture Radar (SAR information processing and applications very difficult. This situation has become one of the main bottlenecks in the interpretation of the target scattering mechanism and quantitative applications. In this work, we review and introduce a new interpretation of the target scattering mechanism in the rotation domain along the radar line of sight. This concept includes the recently established uniform polarimetric matrix rotation theory and polarimetric coherence pattern visualization and interpretation in the rotation domain. The core idea of target scattering interpretation in the rotation domain is to extend the amount of target information acquired at a given geometry to the rotation domain, which then provides fundamentals for the deep mining and utilization of target scattering information. This work mainly focuses on the investigation of derived new polarimetric feature sets and application demonstrations. Comparison study results validate the promising potential for the application of the established interpretation framework in the rotation domain with respect to target discrimination and classification.

  6. Polarimetric Determination of Starch in Raw Materials and Discharged Waste from Beer Production

    OpenAIRE

    Anca Farcas; Maria Tofana; Sonia Socaci; Stancuta Scrob; Liana Salanta; Doinita Bors

    2013-01-01

    Brewer’s spent grain (BGS) is a by-product of thebrewing process, consisting of the solid fraction of barley malt remainingafter separation of worth. In this research, raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method.

  7. Comparisons of Circular Transmit and Linear Receive Compact Polarimetric SAR Features for Oil Slicks Discrimination

    Directory of Open Access Journals (Sweden)

    Yu Li

    2015-01-01

    Full Text Available Compact polarimetric (CP synthetic aperture radar (SAR has proven its potential in distinguishing oil slicks and look-alikes. Polarimetric information can be retrieved directly from scattering vector or from reconstructed pseudo-Quad-Pol covariance matrix of CP SAR data. In this paper, we analysed features from Circular Transmit and Linear Receive (CTLR CP SAR data that are derived by taking both of these two methods. K-means clustering followed by accuracy assessment was also implemented for performance evaluation. Through experiments that were conducted based on L-band UAVSAR fully polarimetric data, it was found that optimum extraction methods varied for different features. The histogram analysis and segmentation results also demonstrated the comparable performance of CP SAR features in distinguishing different damping properties within oil slicks. This study proposed a framework of statistically analyzing polarimetric SAR (Pol-SAR features and provided guidelines for determining optimum feature extraction methods from CP SAR data and for marine oil-spills detection and classification.

  8. Probe-Fed Stacked Microstrip Patch Antenna for High-Resolution Polarimetric C-Band SAR

    DEFF Research Database (Denmark)

    Granholm, Johan; Skou, Niels

    2000-01-01

    The paper describes a C-band, dual-linear polarization wideband antenna for use in the next-generation of the Danish high-resolution, airborne polarimetric synthetic aperture radar (SAR) system, EMISAR. The design and performance of a probe-fed, stacked microstrip patch element, operating from 4...

  9. The PHARUS Project; Real Time Digital Processing of Airborne Polarimetric Radar Signals

    NARCIS (Netherlands)

    Pouwels, H.; Hoogeboom, P.; Koomen, P.J.; Snoeij, P.

    1992-01-01

    The Dutch PHARUS project aims for the developrlenÈ of a polarimetric C-band aircraft SAR, to be finalized in 1994. The PHARUS systen consists of three subsystens: the radar, the subsystem for the onboard data processing and recording and the ground-based subsystem for SAR processing. PHARUS is a

  10. Validation of Distributed Soil Moisture: Airborne Polarimetric SAR vs. Ground-based Sensor Networks

    Science.gov (United States)

    Jagdhuber, T.; Kohling, M.; Hajnsek, I.; Montzka, C.; Papathanassiou, K. P.

    2012-04-01

    The knowledge of spatially distributed soil moisture is highly desirable for an enhanced hydrological modeling in terms of flood prevention and for yield optimization in combination with precision farming. Especially in mid-latitudes, the growing agricultural vegetation results in an increasing soil coverage along the crop cycle. For a remote sensing approach, this vegetation influence has to be separated from the soil contribution within the resolution cell to extract the actual soil moisture. Therefore a hybrid decomposition was developed for estimation of soil moisture under vegetation cover using fully polarimetric SAR data. The novel polarimetric decomposition combines a model-based decomposition, separating the volume component from the ground components, with an eigen-based decomposition of the two ground components into a surface and a dihedral scattering contribution. Hence, this hybrid decomposition, which is based on [1,2], establishes an innovative way to retrieve soil moisture under vegetation. The developed inversion algorithm for soil moisture under vegetation cover is applied on fully polarimetric data of the TERENO campaign, conducted in May and June 2011 for the Rur catchment within the Eifel/Lower Rhine Valley Observatory. The fully polarimetric SAR data were acquired in high spatial resolution (range: 1.92m, azimuth: 0.6m) by DLR's novel F-SAR sensor at L-band. The inverted soil moisture product from the airborne SAR data is validated with corresponding distributed ground measurements for a quality assessment of the developed algorithm. The in situ measurements were obtained on the one hand by mobile FDR probes from agricultural fields near the towns of Merzenhausen and Selhausen incorporating different crop types and on the other hand by distributed wireless sensor networks (SoilNet clusters) from a grassland test site (near the town of Rollesbroich) and from a forest stand (within the Wüstebach sub-catchment). Each SoilNet cluster

  11. SRHA calibration curve

    Data.gov (United States)

    U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...

  12. Bond yield curve construction

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available In the broadest sense, yield curve indicates the market's view of the evolution of interest rates over time. However, given that cost of borrowing it closely linked to creditworthiness (ability to repay, different yield curves will apply to different currencies, market sectors, or even individual issuers. As government borrowing is indicative of interest rate levels available to other market players in a particular country, and considering that bond issuance still remains the dominant form of sovereign debt, this paper describes yield curve construction using bonds. The relationship between zero-coupon yield, par yield and yield to maturity is given and their usage in determining curve discount factors is described. Their usage in deriving forward rates and pricing related derivative instruments is also discussed.

  13. 5-day photo-polarimetric WEBT Campaign on Blazar S5 0716+714 - a Study of Microvariabiltiy in Blazar

    Science.gov (United States)

    Bhatta, Gopal; Ostrwoski, Michal; Stawarz, Lukasz; Zola, Staszek; Jableka, Damian; Bachev, R.; Benitez, Erika; Dhalla, Sarah M.; Cason, Andy; Carosati, Daniele; Damljanovic, Goran; Frasca, A.; Hu, Shao Ming; Jorstad, Svetlana G.; Kurtanidze, O.; Larionov, Valeri; Leto, Giuseppe; Marscher, Alan P.; Moody, Joseph; Ohlert, Johhanes; Rizzi, Nicola; Sadun, Alberto C.; Sasada, Mahito; Sergeev, Sergey; Strigachev, Anton; Vince, Oliver; Webb, James Raymond; Whole Earth Blazar Telescope

    2015-01-01

    A whole earth blazar telescope (WEBT) campaign on blazar S5 0716+714 was organized to simultaneously monitor the source in multiple photo-polarimetric filters as a study of the nature of microvariability in blazar. The campaign, starting on March 2nd 2014, lasted for five consecutive days resulting in a rich data set- flux in B,V,R,I and near IR filters, and polarization degree (PD) and position angle (PA) in mainly R filter. Such a rich information provides with an unique opportunity to look deep into the localized emission regions in the jet of the blazar. During the campaign, the source remained active with 0.93 duty cycle and went through an oscillation of 0.3 magnitudes along with 5% change in PD and 50 degrees swing in PA. For 6.19 hrs the activity suddenly stopped in all the filters resulting in a plateau around 14 magnitudes in R filter light curve and then brightens by 0.14 mag in 2.96 hr time. We employed time series analysis in search of possible quasi-periodic oscillations and found some of the significant timescales present in the light curve which could reflect on the physical processes in the turbulent jet environment. In the color-magnitude analysis, we looked for 'bluer-when-brighter' trend widely claimed to be found in some of the blazars including the source. Although we found some of such incidences, they could not claimed to be persistent through out the campaign period. Similarly, no clear trend of correlation between flux and PD, and flux and PA could be established. A modeling of the mini-flares lasting few hours as stochastic synchrotron pulses on top of relative stable back ground emission and that incorporates simultaneous the change of color, PA and PD is underway.

  14. Analysis of Radarsat-2 Full Polarimetric Data for Forest Mapping

    Science.gov (United States)

    Maghsoudi, Yasser

    Forests are a major natural resource of the Earth and control a wide range of environmental processes. Forests comprise a major part of the planet's plant biodiversity and have an important role in the global hydrological and biochemical cycles. Among the numerous potential applications of remote sensing in forestry, forest mapping plays a vital role for characterization of the forest in terms of species. Particularly, in Canada where forests occupy 45% of the territory, representing more than 400 million hectares of the total Canadian continental area. In this thesis, the potential of polarimetric SAR (PolSAR) Radarsat-2 data for forest mapping is investigated. This thesis has two principle objectives. First is to propose algorithms for analyzing the PolSAR image data for forest mapping. There are a wide range of SAR parameters that can be derived from PolSAR data. In order to make full use of the discriminative power offered by all these parameters, two categories of methods are proposed. The methods are based on the concept of feature selection and classifier ensemble. First, a nonparametric definition of the evaluation function is proposed and hence the methods NFS and CBFS. Second, a fast wrapper algorithm is proposed for the evaluation function in feature selection and hence the methods FWFS and FWCBFS. Finally, to incorporate the neighboring pixels information in classification an extension of the FWCBFS method i.e. CCBFS is proposed. The second objective of this thesis is to provide a comparison between leaf-on (summer) and leaf-off (fall) season images for forest mapping. Two Radarsat-2 images acquired in fine quad-polarized mode were chosen for this study. The images were collected in leaf-on and leaf-off seasons. We also test the hypothesis whether combining the SAR parameters obtained from both images can provide better results than either individual datasets. The rationale for this combination is that every dataset has some parameters which may be

  15. The Jordan Curve Theorem

    Indian Academy of Sciences (India)

    We had defined when an arc is said to cross a circle. We broaden the definition of crossing as follows: Definition: Suppose f is a piece-wise circular simple closed curve and, is a piece-wise circular arc. Suppose ..... curve formed by p' pp", q' qq", part of r between p' and q' and part of r between pI! and q", as shown (Figures 6 ...

  16. Power Curve Measurements FGW

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Federici, Paolo

    This report describes power curve measurements carried out on a given turbine in a chosen period. The measurements are carried out in accordance to IEC 61400-12-1 Ed. 1 and FGW Teil 2.......This report describes power curve measurements carried out on a given turbine in a chosen period. The measurements are carried out in accordance to IEC 61400-12-1 Ed. 1 and FGW Teil 2....

  17. Attempts to separate (-)-α-thujone, (+)-β-thujone epimers from camphor enantiomers by enantioselective HPLC with polarimetric detection.

    Science.gov (United States)

    El Montassir, Dahmane; Aamouche, Ahmed; Vanthuyne, Nicolas; Jean, Marion; Vanloot, Pierre; Taourirte, Moha; Dupuy, Nathalie; Roussel, Christian

    2013-03-01

    In a first step, 26 chiral stationary phases (CSPs) have been screened for the separation of (-)-α-thujone, (+)-β-thujone epimers and camphor enantiomers by LC. The separations were monitored by a polarimeter detector. None of these CSPs provided a noticeable resolution for camphor enantiomers. The three components of a test mixture were clearly baseline separated on Chiralpak AS-H, Chiralpak AZ-H and TCI-MBS (poly(N-alpha-(S)-methylbenzylmaleimide) coated on silica gel) in a mobile phase composed of hexane/2-PrOH (99:1 v/v). Interestingly, for a preparative application, the three CSPs produced different elution orders for the three constituents of the mixture. In a second step, it is shown that the use of online polarimetric detection constitutes an unprecedented method to reveal the occurrence and the relative content of thujone epimers and the chirality of the major camphor enantiomer in crude essential oils. A proof of concept is illustrated on crude essential oils from Rosmarinus tournefortii, Artemisia herba alba and A. arborescens, which grow in Morocco and have several traditional uses there. In a third step, pure (+)-β-thujone was quantitatively collected from A. arborescens crude oil by semi-preparative HPLC on Chiralpak AZ-H monitored by a polarimeter. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Design and Characterization of Optical Metamaterials Using Tunable Polarimetric Scatterometry

    Science.gov (United States)

    2012-12-01

    the right column plots represent dispersion curve for AlSb , AlAs, AlN, Al2O3, SiO2 and MgF2 from top to bottom. 40 7 Page Figure 3-3. (a...meets the design constraint. The dotted lines on the right column plots represent dispersion curve for AlSb , AlAs, AlN, Al2O3, SiO2 and MgF2 from top...dotted lines refer to dispersion curves for common dielectrics; from top-to-bottom, they are AlSb , AlAs, AlN, Al2O3, SiO2, and MgF2. The next step in

  19. High Resolution Processing with an Active Phased Array SAR

    NARCIS (Netherlands)

    Nijenboer, F.J.; Otten, M.P.G.

    1999-01-01

    The Dutch PHARUS system is a polarimetric active phased array SAR capable of performing advanced SAR modes. Advanced SAR modes that are being investigated are: spotlight SAR, sliding spotlight SAR, stepped frequency SAR and interferometric SAR. The flight experiments and automatic beam steering

  20. Classification of Polarimetric SAR Image Based on Support Vector Machine Using Multiple-Component Scattering Model and Texture Features

    Directory of Open Access Journals (Sweden)

    Lamei Zhang

    2010-01-01

    Full Text Available The classification of polarimetric SAR image based on Multiple-Component Scattering Model (MCSM and Support Vector Machine (SVM is presented in this paper. MCSM is a potential decomposition method for a general condition. SVM is a popular tool for machine learning tasks involving classification, recognition, or detection. The scattering powers of single-bounce, double-bounce, volume, helix, and wire scattering components are extracted from fully polarimetric SAR images. Combining with the scattering powers of MCSM and the selected texture features from Gray-level cooccurrence matrix (GCM, SVM is used for the classification of polarimetric SAR image. We generate a validity test for the proposed method using Danish EMISAR L-band fully polarimetric data of Foulum Area (DK, Denmark. The preliminary result indicates that this method can classify most of the areas correctly.

  1. GPM GROUND VALIDATION NASA S-BAND DUAL POLARIMETRIC (NPOL) DOPPLER RADAR MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-band Dual Polarimetric (NPOL) Doppler Radar MC3E dataset was collected by the NASA NPOL radar, which was developed by a research...

  2. PolSAR Land Cover Classification Based on Roll-Invariant and Selected Hidden Polarimetric Features in the Rotation Domain

    Directory of Open Access Journals (Sweden)

    Chensong Tao

    2017-07-01

    Full Text Available Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR. Target polarimetric response is strongly dependent on its orientation. Backscattering responses of the same target with different orientations to the SAR flight path may be quite different. This target orientation diversity effect hinders PolSAR image understanding and interpretation. Roll-invariant polarimetric features such as entropy, anisotropy, mean alpha angle, and total scattering power are independent of the target orientation and are commonly adopted for PolSAR image classification. On the other aspect, target orientation diversity also contains rich information which may not be sensed by roll-invariant polarimetric features. In this vein, only using the roll-invariant polarimetric features may limit the final classification accuracy. To address this problem, this work uses the recently reported uniform polarimetric matrix rotation theory and a visualization and characterization tool of polarimetric coherence pattern to investigate hidden polarimetric features in the rotation domain along the radar line of sight. Then, a feature selection scheme is established and a set of hidden polarimetric features are selected in the rotation domain. Finally, a classification method is developed using the complementary information between roll-invariant and selected hidden polarimetric features with a support vector machine (SVM/decision tree (DT classifier. Comparison experiments are carried out with NASA/JPL AIRSAR and multi-temporal UAVSAR data. For AIRSAR data, the overall classification accuracy of the proposed classification method is 95.37% (with SVM/96.38% (with DT, while that of the conventional classification method is 93.87% (with SVM/94.12% (with DT, respectively. Meanwhile, for multi-temporal UAVSAR data, the mean overall classification accuracy of the proposed method is up to 97.47% (with SVM/99.39% (with DT, which is also higher

  3. Power Curve Measurements REWS

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Vesth, Allan

    This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere......This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...

  4. Algebraic curves and cryptography

    CERN Document Server

    Murty, V Kumar

    2010-01-01

    It is by now a well-known paradigm that public-key cryptosystems can be built using finite Abelian groups and that algebraic geometry provides a supply of such groups through Abelian varieties over finite fields. Of special interest are the Abelian varieties that are Jacobians of algebraic curves. All of the articles in this volume are centered on the theme of point counting and explicit arithmetic on the Jacobians of curves over finite fields. The topics covered include Schoof's \\ell-adic point counting algorithm, the p-adic algorithms of Kedlaya and Denef-Vercauteren, explicit arithmetic on

  5. Complementary curves of descent

    Science.gov (United States)

    Mungan, Carl E.; Lipscombe, Trevor C.

    2013-01-01

    The shapes of two wires in a vertical plane with the same starting and ending points are described as complementary curves of descent if beads frictionlessly slide down both of them in the same time, starting from rest. Every analytic curve has a unique complement, except for a cycloid (solution of the brachistochrone problem), which is self complementary. A striking example is a straight wire whose complement is a lemniscate of Bernoulli. Alternatively, the wires can be tracks down which round objects undergo a rolling race. The level of presentation is appropriate for an intermediate undergraduate course in classical mechanics.

  6. Multifrequency Photo-polarimetric WEBT Observation Campaign on the Blazar S5 0716+714: Source Microvariability and Search for Characteristic Timescales

    Science.gov (United States)

    Bhatta, G.; Stawarz, Ł.; Ostrowski, M.; Markowitz, A.; Akitaya, H.; Arkharov, A. A.; Bachev, R.; Benítez, E.; Borman, G. A.; Carosati, D.; Cason, A. D.; Chanishvili, R.; Damljanovic, G.; Dhalla, S.; Frasca, A.; Hiriart, D.; Hu, S.-M.; Itoh, R.; Jableka, D.; Jorstad, S.; Jovanovic, M. D.; Kawabata, K. S.; Klimanov, S. A.; Kurtanidze, O.; Larionov, V. M.; Laurence, D.; Leto, G.; Marscher, A. P.; Moody, J. W.; Moritani, Y.; Ohlert, J. M.; Di Paola, A.; Raiteri, C. M.; Rizzi, N.; Sadun, A. C.; Sasada, M.; Sergeev, S.; Strigachev, A.; Takaki, K.; Troitsky, I. S.; Ui, T.; Villata, M.; Vince, O.; Webb, J. R.; Yoshida, M.; Zola, S.

    2016-11-01

    Here we report on the results of the Whole Earth Blazar Telescope photo-polarimetric campaign targeting the blazar S5 0716+71, organized in 2014 March to monitor the source simultaneously in BVRI and near-IR filters. The campaign resulted in an unprecedented data set spanning ∼110 hr of nearly continuous, multiband observations, including two sets of densely sampled polarimetric data mainly in the R filter. During the campaign, the source displayed pronounced variability with peak-to-peak variations of about 30% and “bluer-when-brighter” spectral evolution, consisting of a day-timescale modulation with superimposed hour-long microflares characterized by ∼0.1 mag flux changes. We performed an in-depth search for quasi-periodicities in the source light curve; hints for the presence of oscillations on timescales of ∼3 and ∼5 hr do not represent highly significant departures from a pure red-noise power spectrum. We observed that, at a certain configuration of the optical polarization angle (PA) relative to the PA of the innermost radio jet in the source, changes in the polarization degree (PD) led the total flux variability by about 2 hr; meanwhile, when the relative configuration of the polarization and jet angles altered, no such lag could be noted. The microflaring events, when analyzed as separate pulse emission components, were found to be characterized by a very high PD (>30%) and PAs that differed substantially from the PA of the underlying background component, or from the radio jet positional angle. We discuss the results in the general context of blazar emission and energy dissipation models. ).

  7. MULTIFREQUENCY PHOTO-POLARIMETRIC WEBT OBSERVATION CAMPAIGN ON THE BLAZAR S5 0716+714: SOURCE MICROVARIABILITY AND SEARCH FOR CHARACTERISTIC TIMESCALES

    Energy Technology Data Exchange (ETDEWEB)

    Bhatta, G.; Stawarz, Ł.; Ostrowski, M. [Astronomical Observatory of Jagiellonian University, ul. Orla 171, 30-244 Krakow (Poland); Markowitz, A. [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0424 (United States); Akitaya, H. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Arkharov, A. A. [Main (Pulkovo) Astronomical Observatory of RAS, Pulkovskoye shosse, 60, 196140 St. Petersburg (Russian Federation); Bachev, R. [Institute of Astronomy, Bulgarian Academy of Sciences, 72, Tsarigradsko Shosse Blvd., 1784 Sofia (Bulgaria); Benítez, E. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Mexico DF (Mexico); Borman, G. A. [Crimean Astrophysical Observatory, P/O Nauchny, Crimea, 298409 (Russian Federation); Carosati, D. [EPT Observatories, Tijarafe, La Palma (Spain); Cason, A. D. [Private address, 105 Glen Pine Trail, Dawnsonville, GA 30534 (United States); Chanishvili, R. [Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia (United States); Damljanovic, G. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Dhalla, S. [Florida International University, Miami, FL 33199 (United States); Frasca, A. [INAF—Osservatorio Astrofisico di Catania (Italy); Hiriart, D. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada (Mexico); Hu, S-M., E-mail: gopalbhatta716@gmail.com [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University at Weihai, 264209 Weihai (China); and others

    2016-11-01

    Here we report on the results of the Whole Earth Blazar Telescope photo-polarimetric campaign targeting the blazar S5 0716+71, organized in 2014 March to monitor the source simultaneously in BVRI and near-IR filters. The campaign resulted in an unprecedented data set spanning ∼110 hr of nearly continuous, multiband observations, including two sets of densely sampled polarimetric data mainly in the R filter. During the campaign, the source displayed pronounced variability with peak-to-peak variations of about 30% and “bluer-when-brighter” spectral evolution, consisting of a day-timescale modulation with superimposed hour-long microflares characterized by ∼0.1 mag flux changes. We performed an in-depth search for quasi-periodicities in the source light curve; hints for the presence of oscillations on timescales of ∼3 and ∼5 hr do not represent highly significant departures from a pure red-noise power spectrum. We observed that, at a certain configuration of the optical polarization angle (PA) relative to the PA of the innermost radio jet in the source, changes in the polarization degree (PD) led the total flux variability by about 2 hr; meanwhile, when the relative configuration of the polarization and jet angles altered, no such lag could be noted. The microflaring events, when analyzed as separate pulse emission components, were found to be characterized by a very high PD (>30%) and PAs that differed substantially from the PA of the underlying background component, or from the radio jet positional angle. We discuss the results in the general context of blazar emission and energy dissipation models.

  8. Carbon Lorenz Curves

    NARCIS (Netherlands)

    Groot, L.F.M.|info:eu-repo/dai/nl/073642398

    2008-01-01

    The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across

  9. Learning curves for insertion

    African Journals Online (AJOL)

    Adele

    Introduction. Both the Unique™ LMA, and lately the Cobra™ PLA, is available in most of the larger state hospitals in South Africa. This study's objective is to evaluate and compare the learning curves for insertion of these two single-use airway devices. This is to ascertain which of these two devices is easier and safer to ...

  10. Power Curve Measurements

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....

  11. Power Curve Measurements

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...

  12. Power Curve Measurements

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Villanueva, Héctor

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine...

  13. Power Curve Measurements, FGW

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....

  14. Power Curve Measurements

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Villanueva, Héctor

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present anal...

  15. Power Curve Measurements REWS

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Vesth, Allan

    This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere...

  16. Power Curve Measurements FGW

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Villanueva, Héctor

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present anal...

  17. Textbook Factor Demand Curves.

    Science.gov (United States)

    Davis, Joe C.

    1994-01-01

    Maintains that teachers and textbook graphics follow the same basic pattern in illustrating changes in demand curves when product prices increase. Asserts that the use of computer graphics will enable teachers to be more precise in their graphic presentation of price elasticity. (CFR)

  18. Power curve report

    DEFF Research Database (Denmark)

    Vesth, Allan; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....

  19. Power Curve Measurements REWS

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    , the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...

  20. Power Curve Measurements, REWS

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    , the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...

  1. Power Curve Measurements FGW

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine...

  2. Nacelle lidar power curve

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Wagner, Rozenn

    This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...

  3. Estimating Forest Vertical Structure from Multialtitude, Fixed-Baseline Radar Interferometric and Polarimetric Data

    Science.gov (United States)

    Treuhaft, Robert N.; Law, Beverly E.; Siqueira, Paul R.

    2000-01-01

    Parameters describing the vertical structure of forests, for example tree height, height-to-base-of-live-crown, underlying topography, and leaf area density, bear on land-surface, biogeochemical, and climate modeling efforts. Single, fixed-baseline interferometric synthetic aperture radar (INSAR) normalized cross-correlations constitute two observations from which to estimate forest vertical structure parameters: Cross-correlation amplitude and phase. Multialtitude INSAR observations increase the effective number of baselines potentially enabling the estimation of a larger set of vertical-structure parameters. Polarimetry and polarimetric interferometry can further extend the observation set. This paper describes the first acquisition of multialtitude INSAR for the purpose of estimating the parameters describing a vegetated land surface. These data were collected over ponderosa pine in central Oregon near longitude and latitude -121 37 25 and 44 29 56. The JPL interferometric TOPSAR system was flown at the standard 8-km altitude, and also at 4-km and 2-km altitudes, in a race track. A reference line including the above coordinates was maintained at 35 deg for both the north-east heading and the return southwest heading, at all altitudes. In addition to the three altitudes for interferometry, one line was flown with full zero-baseline polarimetry at the 8-km altitude. A preliminary analysis of part of the data collected suggests that they are consistent with one of two physical models describing the vegetation: 1) a single-layer, randomly oriented forest volume with a very strong ground return or 2) a multilayered randomly oriented volume; a homogeneous, single-layer model with no ground return cannot account for the multialtitude correlation amplitudes. Below the inconsistency of the data with a single-layer model is followed by analysis scenarios which include either the ground or a layered structure. The ground returns suggested by this preliminary analysis seem

  4. Photometric and polarimetric variability and mass-loss rate of the massive binary Wolf-Rayet star HDE 311884 (WN6 + 05: V)

    International Nuclear Information System (INIS)

    Moffat, A.F.J.; Drissen, L.; Robert, C.; Lamontagne, R.; Coziol, R.

    1990-01-01

    Photometric and polarimetric monitoring of the Wolf-Rayet (W-R) + O-type binary system HDE 311884 = WR 47 over many orbital cycles shows the clear effects of phase-dependent electron scattering of O-star light as the orbiting O companion shines through varying column density of W-R stellar wind material. In contrast to this wind-type eclipse, the stars themselves do not quite eclipse. Both photometry and polarimetry give a consistent estimate of the mass-loss rate of the W-R component: at about 0.00003 solar mass/yr. The orbital inclination, i = 70 deg, along with the previously published velocity orbit, yields high masses: M(WN6) = 48 solar masses and M(O5:V) = 57 solar masses. 33 refs

  5. Investigation of the Capability of Compact Polarimetric SAR Interferometry to Estimate Forest Height

    Science.gov (United States)

    Zhang, Hong; Xie, Lei; Wang, Chao; Chen, Jiehong

    2013-08-01

    The main objective of this paper is to investigate the capability of compact Polarimetric SAR Interferometry (C-PolInSAR) on forest height estimation. For this, the pseudo fully polarimetric interferomteric (F-PolInSAR) covariance matrix is firstly reconstructed, then the three- stage inversion algorithm, hybrid algorithm, Music and Capon algorithm are applied to both C-PolInSAR covariance matrix and pseudo F-PolInSAR covariance matrix. The availability of forest height estimation is demonstrated using L-band data generated by simulator PolSARProSim and X-band airborne data acquired by East China Research Institute of Electronic Engineering, China Electronics Technology Group Corporation.

  6. The effects of thermal equilibrium and contrast in LWIR polarimetric images.

    Science.gov (United States)

    Tyo, J Scott; Ratliff, Bradley M; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P

    2007-11-12

    Long-wave infrared (LWIR) polarimetric signatures provide the potential for day-night detection and identification of objects in remotely sensed imagery. The source of optical energy in the LWIR is usually due to thermal emission from the object in question, which makes the signature dependent primarily on the target and not on the external environment. In this paper we explore the impact of thermal equilibrium and the temperature of (unseen) background objects on LWIR polarimetric signatures. We demonstrate that an object can completely lose its polarization signature when it is in thermal equilibrium with its optical background, even if it has thermal contrast with the objects that appear behind it in the image.

  7. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    Directory of Open Access Journals (Sweden)

    T. H. Raupach

    2017-07-01

    Full Text Available A new technique for estimating the raindrop size distribution (DSD from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed using a double-moment normalisation. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observations. In the three tested domains, in terms of DSD moments, rain rate, and characteristic drop diameter, the proposed method performs similarly to and often better than a state-of-the-art DSD-retrieval technique. The approach is flexible because no specific DSD model is prescribed. In addition, a method is proposed to treat noisy radar data to improve DSD-retrieval performance with radar measurements.

  8. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    Science.gov (United States)

    Raupach, Timothy H.; Berne, Alexis

    2017-07-01

    A new technique for estimating the raindrop size distribution (DSD) from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed using a double-moment normalisation. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observations. In the three tested domains, in terms of DSD moments, rain rate, and characteristic drop diameter, the proposed method performs similarly to and often better than a state-of-the-art DSD-retrieval technique. The approach is flexible because no specific DSD model is prescribed. In addition, a method is proposed to treat noisy radar data to improve DSD-retrieval performance with radar measurements.

  9. Photo-polarimetric sensitivities to layering and mixing of absorbing aerosols

    Directory of Open Access Journals (Sweden)

    O. V. Kalashnikova

    2011-09-01

    Full Text Available We investigate to what extent multi-angle polarimetric measurements are sensitive to vertical mixing/layering of absorbing aerosols, adopting calibration uncertainty of 1.5% in intensity and 0.5% in the degree of linear polarization of Multiangle Spectro-Polarimetric Imager (MSPI. Employing both deterministic and Monte Carlo radiative transfer codes with polarization, we conduct modeling experiments to determine how the measured Stokes vector elements are affected at UV and short visible wavelengths by the vertical distribution, mixing and layering of smoke and dust aerosols for variety of microphysical parameters. We find that multi-angular polarimetry holds the potential to infer dust-layer heights and thicknesses at blue visible channel due to its lesser sensitivity to changes in dust coarse mode optical properties, but higher sensitivity to the dust vertical profiles. Our studies quantify requirements for obtaining simultaneous information on aerosol layer height and absorption under MSPI measurement uncertainties.

  10. Investigation of hydrometeor classification uncertainties through the POLARRIS polarimetric radar simulator

    Science.gov (United States)

    Dolan, B.; Rutledge, S. A.; Barnum, J. I.; Matsui, T.; Tao, W. K.; Iguchi, T.

    2017-12-01

    POLarimetric Radar Retrieval and Instrument Simulator (POLARRIS) is a framework that has been developed to simulate radar observations from cloud resolving model (CRM) output and subject model data and observations to the same retrievals, analysis and visualization. This framework not only enables validation of bulk microphysical model simulated properties, but also offers an opportunity to study the uncertainties associated with retrievals such as hydrometeor classification (HID). For the CSU HID, membership beta functions (MBFs) are built using a set of simulations with realistic microphysical assumptions about axis ratio, density, canting angles, size distributions for each of ten hydrometeor species. These assumptions are tested using POLARRIS to understand their influence on the resulting simulated polarimetric data and final HID classification. Several of these parameters (density, size distributions) are set by the model microphysics, and therefore the specific assumptions of axis ratio and canting angle are carefully studied. Through these sensitivity studies, we hope to be able to provide uncertainties in retrieved polarimetric variables and HID as applied to CRM output. HID retrievals assign a classification to each point by determining the highest score, thereby identifying the dominant hydrometeor type within a volume. However, in nature, there is rarely just one a single hydrometeor type at a particular point. Models allow for mixing ratios of different hydrometeors within a grid point. We use the mixing ratios from CRM output in concert with the HID scores and classifications to understand how the HID algorithm can provide information about mixtures within a volume, as well as calculate a confidence in the classifications. We leverage the POLARRIS framework to additionally probe radar wavelength differences toward the possibility of a multi-wavelength HID which could utilize the strengths of different wavelengths to improve HID classifications. With

  11. On the possibility of noninvasive polarimetric determination of glucose content in skin

    Science.gov (United States)

    Pravdin, A. B.; Spivak, V. A.; Yakovlev, D. A.

    2016-01-01

    Based on real structure and optical properties of the dermis, we analyzed the possibility of polarimetric measurement of glucose content in the skin. It was shown that, at physiological concentrations of glucose in the interstitial fluid, the optical activity of glucose is not manifested in the polarization and optical properties of the tissue, since the optical activity of glucose is almost completely suppressed by the linear birefringence of the dermis.

  12. Approximation by planar elastic curves

    DEFF Research Database (Denmark)

    Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge

    2016-01-01

    We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient-driven...

  13. Carbon Lorenz Curves

    Energy Technology Data Exchange (ETDEWEB)

    Groot, L. [Utrecht University, Utrecht School of Economics, Janskerkhof 12, 3512 BL Utrecht (Netherlands)

    2008-11-15

    The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across countries. These tools allow policy-makers and the general public to grasp at a single glance the impact of conventional distribution rules such as equal caps or grandfathering, or more sophisticated ones, on the distribution of greenhouse gas emissions. Second, using the Samuelson rule for the optimal provision of a public good, the Pareto-optimal distribution of carbon emissions is compared with the distribution that follows if countries follow Nash-Cournot abatement strategies. It is shown that the Pareto-optimal distribution under the Samuelson rule can be approximated by the equal cap division, represented by the diagonal in the Lorenz curve diagram.

  14. Power curve investigation

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report describes the analysis carried out with data from a given turbine in a wind farm and a chosen period. The purpose of the analysis is to correlate the power output of the wind turbine to the wind speed measured by a nacelle-mounted anemometer. The measurements and analysis are not perf......This report describes the analysis carried out with data from a given turbine in a wind farm and a chosen period. The purpose of the analysis is to correlate the power output of the wind turbine to the wind speed measured by a nacelle-mounted anemometer. The measurements and analysis...... are not performed according to IEC 61400-12-1 [1]. Therefore, the results presented in this report cannot be considered a power curve according to the reference standard, and are referred to as “power curve investigation” instead. The measurements have been performed by a customer and the data analysis has been...

  15. Managing curved canals

    Directory of Open Access Journals (Sweden)

    Iram Ansari

    2012-01-01

    Full Text Available Dilaceration is the result of a developmental anomaly in which there has been an abrupt change in the axial inclination between the crown and the root of a tooth. Dilaceration can be seen in both the permanent and deciduous dentitions, and is more commonly found in posterior teeth and in maxilla. Periapical radiographs are the most appropriate way to diagnose the presence of root dilacerations. The controlled regularly tapered preparation of the curved canals is the ultimate challenge in endodontics. Careful and meticulous technique will yield a safe and sufficient enlargement of the curved canals. This article gives a review of the literature and three interesting case reports of root dilacerations.

  16. Research on visible and near infrared spectral-polarimetric properties of soil polluted by crude oil

    Science.gov (United States)

    Shen, Hui-yan; Zhou, Pu-cheng; Pan, Bang-long

    2017-10-01

    Hydrocarbon contaminated soil can impose detrimental effects on forest health and quality of agricultural products. To manage such consequences, oil leak indicators should be detected quickly by monitoring systems. Remote sensing is one of the most suitable techniques for monitoring systems, especially for areas which are uninhabitable and difficulty to access. The most available physical quantities in optical remote sensing domain are the intensity and spectral information obtained by visible or infrared sensors. However, besides the intensity and wavelength, polarization is another primary physical quantity associated with an optical field. During the course of reflecting light-wave, the surface of soil polluted by crude oil will cause polarimetric properties which are related to the nature of itself. Thus, detection of the spectralpolarimetric properties for soil polluted by crude oil has become a new remote sensing monitoring method. In this paper, the multi-angle spectral-polarimetric instrument was used to obtain multi-angle visible and near infrared spectralpolarimetric characteristic data of soil polluted by crude oil. And then, the change rule between polarimetric properties with different affecting factors, such as viewing zenith angle, incidence zenith angle of the light source, relative azimuth angle, waveband of the detector as well as different grain size of soil were discussed, so as to provide a scientific basis for the research on polarization remote sensing for soil polluted by crude oil.

  17. IMPROVED SEARCH OF PRINCIPAL COMPONENT ANALYSIS DATABASES FOR SPECTRO-POLARIMETRIC INVERSION

    International Nuclear Information System (INIS)

    Casini, R.; Lites, B. W.; Ramos, A. Asensio; Ariste, A. López

    2013-01-01

    We describe a simple technique for the acceleration of spectro-polarimetric inversions based on principal component analysis (PCA) of Stokes profiles. This technique involves the indexing of the database models based on the sign of the projections (PCA coefficients) of the first few relevant orders of principal components of the four Stokes parameters. In this way, each model in the database can be attributed a distinctive binary number of 2 4n bits, where n is the number of PCA orders used for the indexing. Each of these binary numbers (indices) identifies a group of ''compatible'' models for the inversion of a given set of observed Stokes profiles sharing the same index. The complete set of the binary numbers so constructed evidently determines a partition of the database. The search of the database for the PCA inversion of spectro-polarimetric data can profit greatly from this indexing. In practical cases it becomes possible to approach the ideal acceleration factor of 2 4n as compared to the systematic search of a non-indexed database for a traditional PCA inversion. This indexing method relies on the existence of a physical meaning in the sign of the PCA coefficients of a model. For this reason, the presence of model ambiguities and of spectro-polarimetric noise in the observations limits in practice the number n of relevant PCA orders that can be used for the indexing

  18. Assessment of Polarimetric SAR Interferometry for Improving Ship Classification based on Simulated Data

    Directory of Open Access Journals (Sweden)

    Jordi J. Mallorqui

    2008-12-01

    Full Text Available This paper uses a complete and realistic SAR simulation processing chain, GRECOSAR, to study the potentialities of Polarimetric SAR Interferometry (POLInSAR in the development of new classification methods for ships. Its high processing efficiency and scenario flexibility have allowed to develop exhaustive scattering studies. The results have revealed, first, vessels’ geometries can be described by specific combinations of Permanent Polarimetric Scatterers (PePS and, second, each type of vessel could be characterized by a particular spatial and polarimetric distribution of PePS. Such properties have been recently exploited to propose a new Vessel Classification Algorithm (VCA working with POLInSAR data, which, according to several simulation tests, may provide promising performance in real scenarios. Along the paper, explanation of the main steps summarizing the whole research activity carried out with ships and GRECOSAR are provided as well as examples of the main results and VCA validation tests. Special attention will be devoted to the new improvements achieved, which are related to simulations processing a new and highly realistic sea surface model. The paper will show that, for POLInSAR data with fine resolution, VCA can help to classify ships with notable robustness under diverse and adverse observation conditions.

  19. Segmentation of Polarimetric SAR Images Usig Wavelet Transformation and Texture Features

    Science.gov (United States)

    Rezaeian, A.; Homayouni, S.; Safari, A.

    2015-12-01

    Polarimetric Synthetic Aperture Radar (PolSAR) sensors can collect useful observations from earth's surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR) are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT). Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM) and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  20. Effects of surface materials on polarimetric-thermal measurements: applications to face recognition.

    Science.gov (United States)

    Short, Nathaniel J; Yuffa, Alex J; Videen, Gorden; Hu, Shuowen

    2016-07-01

    Materials, such as cosmetics, applied to the face can severely inhibit biometric face-recognition systems operating in the visible spectrum. These products are typically made up of materials having different spectral properties and color pigmentation that distorts the perceived shape of the face. The surface of the face emits thermal radiation, due to the living tissue beneath the surface of the skin. The emissivity of skin is approximately 0.99; in comparison, oil- and plastic-based materials, commonly found in cosmetics and face paints, have an emissivity range of 0.9-0.95 in the long-wavelength infrared part of the spectrum. Due to these properties, all three are good thermal emitters and have little impact on the heat transferred from the face. Polarimetric-thermal imaging provides additional details of the face and is also dependent upon the thermal radiation from the face. In this paper, we provide a theoretical analysis on the thermal conductivity of various materials commonly applied to the face using a metallic sphere. Additionally, we observe the impact of environmental conditions on the strength of the polarimetric signature and the ability to recover geometric details. Finally, we show how these materials degrade the performance of traditional face-recognition methods and provide an approach to mitigating this effect using polarimetric-thermal imaging.

  1. Polarimetric infrared imaging simulation of a synthetic sea surface with Mie scattering.

    Science.gov (United States)

    He, Si; Wang, Xia; Xia, Runqiu; Jin, Weiqi; Liang, Jian'an

    2018-03-01

    A novel method to simulate the polarimetric infrared imaging of a synthetic sea surface with atmospheric Mie scattering effects is presented. The infrared emission, multiple reflections, and infrared polarization of the sea surface and the Mie scattering of aerosols are all included for the first time. At first, a new approach to retrieving the radiative characteristics of a wind-roughened sea surface is introduced. A two-scale method of sea surface realization and the inverse ray tracing of light transfer calculation are combined and executed simultaneously, decreasing the consumption of time and memory dramatically. Then the scattering process that the infrared light emits from the sea surface and propagates in the aerosol particles is simulated with a polarized light Monte Carlo model. Transformations of the polarization state of the light are calculated with the Mie theory. Finally, the polarimetric infrared images of the sea surface of different environmental conditions and detection parameters are generated based on the scattered light detected by the infrared imaging polarimeter. The results of simulation examples show that our polarimetric infrared imaging simulation can be applied to predict the infrared polarization characteristics of the sea surface, model the oceanic scene, and guide the detection in the oceanic environment.

  2. SEGMENTATION OF POLARIMETRIC SAR IMAGES USIG WAVELET TRANSFORMATION AND TEXTURE FEATURES

    Directory of Open Access Journals (Sweden)

    A. Rezaeian

    2015-12-01

    Full Text Available Polarimetric Synthetic Aperture Radar (PolSAR sensors can collect useful observations from earth’s surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT. Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  3. Twists of Elliptic Curves

    Science.gov (United States)

    Kronberg, Max; Soomro, Muhammad Afzal; Top, Jaap

    2017-10-01

    In this note we extend the theory of twists of elliptic curves as presented in various standard texts for characteristic not equal to two or three to the remaining characteristics. For this, we make explicit use of the correspondence between the twists and the Galois cohomology set H^1\\big({G}_{\\overline{K}/K}, \\operatorname{Aut}_{\\overline{K}}(E)\\big). The results are illustrated by examples.

  4. Transvaginal cholecystectomy learning curve.

    Science.gov (United States)

    Wood, Stephanie G; Dai, Feng; Dabu-Bondoc, Susan; Mikhael, Hosni; Vadivelu, Nalini; Duffy, Andrew; Roberts, Kurt E

    2015-07-01

    There are few surgeons in the United States, within private practice and academic centers, currently performing transvaginal cholecystectomies (TVC). The lack of exposure to TVC during residency or fellowship training, coupled with a poorly defined learning curve, further limits interested surgeons who want to apply this technique to their practice. This study describes the learning curve encountered during the introduction of TVC to our academic facility. This study is an analysis of consecutive TVCs performed between August 14, 2009 and August 3, 2012 at an academic center. The TVC patients were divided into sequential quartiles (n = 15/16). The learning curve outcome was measured as the operative time of TVC patients and compared to the operative time of female laparoscopic cholecystectomy (LC) patients performed during the same time period. Sixty-one patients underwent a TVC with a mean age of 38 ± 12 years and mean BMI was 29 ± 6 kg/m(2). Sixty-seven female patients who underwent a LC with average age 41 ± 15 years and average BMI 33 ± 12 kg/m(2). The average operative time of LC patients and TVC patients was 48 ± 20 and 60 ± 17 min, respectively. Significant improvement in TVC operative times was seen between the first (n = 15 TVCs) and second quartiles (p = 0.04) and stayed relatively constant for third quartile, during which there was no statistically significant difference between the mean LC operative time for the second and third TVC quartiles The learning curve of a fellowship-trained surgeon introducing TVC to their surgical repertoire, as measured by improved operative times, can be achieved with approximately 15 cases.

  5. Dynamics of curved fronts

    CERN Document Server

    Pelce, Pierre

    1989-01-01

    In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.

  6. LCC: Light Curves Classifier

    Science.gov (United States)

    Vo, Martin

    2017-08-01

    Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.

  7. Passive Polarimetric Remote Sensing of Snow and Ice

    Science.gov (United States)

    1997-09-30

    ice and snow, we proposed to measure the Stokes parameters, as a function of incidence angle, for growing ice, desalinated ice, new snow, and...orientation of ice crystals, brine channels and air pockets. Although the CRREL facility is well equipped to artificially generate ice (via refrigeration of...calibration and early growth phase of new ice (See figure 2) 26-Feb Growth phase of new ice 26-Feb Old, desalinated ice (See figure 3) Slight surface

  8. Wolff: straight not curved.

    Science.gov (United States)

    Hammer, A

    2017-11-01

    It was 140 years ago that George von Meyer presented his anatomical diagrams of human bones to a meeting in Zurich. There he was told by Prof. Karl Culmann that the trabecular lines shown within the diagram of the upper femur closely resembled those lines of force which Culmann had determined with Graphic Statics to be passing through a curved, loaded Fairbairn crane. This drew the attention of Julius Wolff, who used this as the basis for his 'Trajectorial theory' which was widely accepted and, to date, has been the underlying basis for all biomechanical investigations of this region. Following Wolff and Culmann, the upper femur is considered to be a curved structure and is investigated as such. Unfortunately, this concept is wrong. The upper femur is not curved but is angular. It is formed by the junction of two straight bones, the femoral neck and the femoral shaft, as may be simply seen as the neck/shaft angle constructed on the antero-posterior radiograph of any normal femur. The internal trabecular bone forms only part of the load bearing structure of the femoral neck. The configuration of this trabecular substance in this region suggests that it is related specifically to the force present during flexion and extension movements of the hip joint. This being so, combined with the delayed timing of the appearance of the trabecular columns, it must be questioned as to whether the remodelling of the upper femur is in response to one or to two distinct forces.

  9. The GNSS polarimetric radio-occultation technique to sense precipitation events: a new concept to be tested aboard PAZ Low Earth Satellite

    Science.gov (United States)

    Tomás, Sergio; Oliveras, Santi; Cardellach, Estel; Rius, Antonio

    2013-04-01

    based on the asymmetry between the vertical and horizontal axis of the rain droplets, especially when intense rates of precipitation occur. As a first approximation, the RO signals propagate across the precipitation-volume tangentially, that is, along the local horizontal axis of the droplets. Forward scattering models have been implemented to quantify the sensitivity of L-band signals to different rain rates and precipitation extension being crossed by the signals. The observable considered so far is the polarimetric phase shift: difference between the phase delay suffered by the H- and V-polarizations. Real RO events have been collocated with TRMM precipitation data. The path traveled by the RO signal under a given altitude has been projected on the TRMM grid of observations, to obtain a profile of the precipitation being crossed by the RO link at a given moment of the occultation event. This mechanism has been used to feed the propagation models and thus estimate the polarimetric phase shift that each precipitation event would have induced into the occultation observation. This simulation exercise permits to determine the detectability thresholds and the expected statistics of such collocated events. Methodology and results will be presented.

  10. Light Curve Analysis of SAO23229

    Directory of Open Access Journals (Sweden)

    Ho-Il Kim

    1993-06-01

    Full Text Available We have made UBV light curves of a newly discovered eclipsing binary, SAO23229 at Sobaeksan Astronomy Observatory. We determined a minimum light time of HJD2448636.1170+/-0.0005 that is 3 minutes later than predicted time, and founda peculiar light variation at phase 0.75 that may not be secondary eclipse. Orbital period of SAO23229 would be 4.2 days rather than 2.1 days. Our analysis of the light curves shows that SAO23229 has a detached configuration consisting of two almost identical F type main sequence stars.

  11. Minimal genus one curves

    OpenAIRE

    Sadek, Mohammad

    2012-01-01

    In this paper we consider genus one equations of degree $n$, namely a (generalised) binary quartic when $n=2$, a ternary cubic when $n=3$, and a pair of quaternary quadrics when $n=4$. A new definition for the minimality of genus one equations of degree $n$ over local fields is introduced. The advantage of this definition is that it does not depend on invariant theory of genus one curves. We prove that this definition coincides with the classical definition of minimality for all $n\\le4$. As a...

  12. Learning from uncertain curves

    DEFF Research Database (Denmark)

    Mallasto, Anton; Feragen, Aasa

    2017-01-01

    We introduce a novel framework for statistical analysis of populations of nondegenerate Gaussian processes (GPs), which are natural representations of uncertain curves. This allows inherent variation or uncertainty in function-valued data to be properly incorporated in the population analysis....... Using the 2-Wasserstein metric we geometrize the space of GPs with L2 mean and covariance functions over compact index spaces. We prove uniqueness of the barycenter of a population of GPs, as well as convergence of the metric and the barycenter of their finite-dimensional counterparts. This justifies...

  13. Estimation of Paddy Rice Variables with a Modified Water Cloud Model and Improved Polarimetric Decomposition Using Multi-Temporal RADARSAT-2 Images

    Directory of Open Access Journals (Sweden)

    Zhi Yang

    2016-10-01

    Full Text Available Rice growth monitoring is very important as rice is one of the staple crops of the world. Rice variables as quantitative indicators of rice growth are critical for farming management and yield estimation, and synthetic aperture radar (SAR has great advantages for monitoring rice variables due to its all-weather observation capability. In this study, eight temporal RADARSAT-2 full-polarimetric SAR images were acquired during rice growth cycle and a modified water cloud model (MWCM was proposed, in which the heterogeneity of the rice canopy in the horizontal direction and its phenological changes were considered when the double-bounce scattering between the rice canopy and the underlying surface was firstly considered as well. Then, three scattering components from an improved polarimetric decomposition were coupled with the MWCM, instead of the backscattering coefficients. Using a genetic algorithm, eight rice variables were estimated, such as the leaf area index (LAI, rice height (h, and the fresh and dry biomass of ears (Fe and De. The accuracy validation showed the MWCM was suitable for the estimation of rice variables during the whole growth season. The validation results showed that the MWCM could predict the temporal behaviors of the rice variables well during the growth cycle (R2 > 0.8. Compared with the original water cloud model (WCM, the relative errors of rice variables with the MWCM were much smaller, especially in the vegetation phase (approximately 15% smaller. Finally, it was discussed that the MWCM could be used, theoretically, for extensive applications since the empirical coefficients in the MWCM were determined in general cases, but more applications of the MWCM are necessary in future work.

  14. The genus curve of the Abell clusters

    Science.gov (United States)

    Rhoads, James E.; Gott, J. Richard, III; Postman, Marc

    1994-01-01

    We study the topology of large-scale structure through a genus curve measurement of the recent Abell catalog redshift survey of Postman, Huchra, and Geller (1992). The structure is found to be spongelike near median density and to exhibit isolated superclusters and voids at high and low densities, respectively. The genus curve shows a slight shift toward 'meatball' topology, but remains consistent with the hypothesis of Gaussian random phase initial conditions. The amplitude of the genus curve corresponds to a power-law spectrum with index n = 0.21(sub -0.47 sup +0.43) on scales of 48/h Mpc or to a cold dark matter power spectrum with omega h = 0.36(sub -0.17 sup +0.46).

  15. Calibration of Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) polarization measurements, and in-flight comparisons with the Research Scanning Polarimeter (RSP) and the Spectropolarimeter for Planetary EXploration (SPEX)

    Science.gov (United States)

    van Harten, G.; Diner, D. J.; Rheingans, B. E.; Daugherty, B. J.; Xu, F.; Bull, M. A.; Tkatcheva, I. N.; Garay, M. J.; Seidel, F.; Chipman, R. A.; Smit, M.

    2016-12-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is a remote sensing instrument for the characterization of atmospheric aerosols and clouds. AirMSPI, flying onboard the NASA ER-2 aircraft at 20 km altitude, participates in field campaigns since 2013, including ORACLES (2016). The pushbroom camera is mounted on a programmable, motorized gimbal for multi-angle observations at 10x10 m2 resolution. Eight spectral bands within 355-935 nm are recorded, 3 of which also measure linear polarization. Photoelastic modulators (PEMs) encode the polarized and total intensities in each polarimetric pixel as the amplitude and offset of a modulated intensity pattern, such that the ratio of the two is insensitive to pixel-to-pixel differences. This technique, developed to enable the high-accuracy imaging polarimetry required for aerosol species discrimination, will also be applied in the Multi-Angle Imager for Aerosols (MAIA) satellite instrument. We present the calibration and accuracy validation of AirMSPI polarization measurements. The main calibration, describing the instrument's response to any degree (DoLP) and angle of linear polarization, is performed in the lab using a recently updated, carefully designed and characterized polarization state generator (PSG-2). Validation measurements using an independent polarimeter show agreement in DoLP to within 0.001 for several DoLPs across the 0-1 range. The PEMs' retardances and phases, which are different and not necessarily stable in flight, are extracted from measurements of the on-board validator, a partially polarized light source located inside the instrument housing, which is viewed before and after each target. Although this calibration does not rely on the validator's DoLP, and the validator was not designed for DoLP calibration, the frequent measurements of its DoLP provide an upper limit for AirMSPI's in-flight polarimetric stability, which is 0.001. A correction for the actual PEM retardances and phases in the

  16. The Characteristic Curves of Water

    Science.gov (United States)

    Neumaier, Arnold; Deiters, Ulrich K.

    2016-09-01

    In 1960, E. H. Brown defined a set of characteristic curves (also known as ideal curves) of pure fluids, along which some thermodynamic properties match those of an ideal gas. These curves are used for testing the extrapolation behaviour of equations of state. This work is revisited, and an elegant representation of the first-order characteristic curves as level curves of a master function is proposed. It is shown that Brown's postulate—that these curves are unique and dome-shaped in a double-logarithmic p, T representation—may fail for fluids exhibiting a density anomaly. A careful study of the Amagat curve (Joule inversion curve) generated from the IAPWS-95 reference equation of state for water reveals the existence of an additional branch.

  17. A Classification Method Based on Polarimetric Entropy and GEV Mixture Model for Intertidal Area of PolSAR Image

    Directory of Open Access Journals (Sweden)

    She Xiaoqiang

    2017-10-01

    Full Text Available This paper proposes a classification method for the intertidal area using quad-polarimetric synthetic aperture radar data. In this paper, a systematic comparison of four well-known multipolarization features is provided so that appropriate features can be selected based on the characteristics of the intertidal area. Analysis result shows that the two most powerful multipolarization features are polarimetric entropy and anisotropy. Furthermore, through our detailed analysis of the scattering mechanisms of the polarimetric entropy, the Generalized Extreme Value (GEV distribution is employed to describe the statistical characteristics of the intertidal area based on the extreme value theory. Consequently, a new classification method is proposed by combining the GEV Mixture Models and the EM algorithm. Finally, experiments are performed on the Radarsat-2 quad-polarization data of the Dongtan intertidal area, Shanghai, to validate our method.

  18. Curved-Duct

    Directory of Open Access Journals (Sweden)

    Je Hyun Baekt

    2000-01-01

    Full Text Available A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a 90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a 90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.

  19. Magnetism in curved geometries

    Science.gov (United States)

    Streubel, Robert

    Deterministically bending and twisting two-dimensional structures in the three-dimensional (3D) space provide means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape. The recent developments of 3D curved magnetic geometries, ranging from theoretical predictions over fabrication to characterization using integral means as well as advanced magnetic tomography, will be reviewed. Theoretical works predict a curvature-induced effective anisotropy and effective Dzyaloshinskii-Moriya interaction resulting in a vast of novel effects including magnetochiral effects (chirality symmetry breaking) and topologically induced magnetization patterning. The remarkable development of nanotechnology, e.g. preparation of high-quality extended thin films, nanowires and frameworks via chemical and physical deposition as well as 3D nano printing, has granted first insights into the fundamental properties of 3D shaped magnetic objects. Optimizing magnetic and structural properties of these novel 3D architectures demands new investigation methods, particularly those based on vector tomographic imaging. Magnetic neutron tomography and electron-based 3D imaging, such as electron holography and vector field electron tomography, are well-established techniques to investigate macroscopic and nanoscopic samples, respectively. At the mesoscale, the curved objects can be investigated using the novel method of magnetic X-ray tomography. In spite of experimental challenges to address the appealing theoretical predictions of curvature-induced effects, those 3D magnetic architectures have already proven their application potential for life sciences, targeted delivery, realization of 3D spin-wave filters, and magneto-encephalography devices, to name just a few. DOE BES MSED (DE-AC02-05-CH11231).

  20. Titration Curves: Fact and Fiction.

    Science.gov (United States)

    Chamberlain, John

    1997-01-01

    Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

  1. Crystals and liquid crystals confined to curved geometries

    OpenAIRE

    Koning, Vinzenz; Vitelli, Vincenzo

    2014-01-01

    This review introduces the elasticity theory of two-dimensional crystals and nematic liquid crystals on curved surfaces, the energetics of topological defects (disclinations, dislocations and pleats) in these ordered phases, and the interaction of defects with the underlying curvature. This chapter concludes with two cases of three-dimensional nematic phases confined to spaces with curved boundaries, namely a torus and a spherical shell.

  2. Critical Factors for Inducing Curved Somatosensory Saccades

    Directory of Open Access Journals (Sweden)

    Tamami Nakano

    2011-10-01

    Full Text Available We are able to make a saccade toward a tactile stimuli to one hand, but trajectories of many saccades curved markedly when the arms were crossed (Groh & Sparks, 2006. However, it remains unknown why some curved and others did not. We therefore examined critical factors for inducing the curved somatosensory saccades. Participants made a saccade as soon as possible from a central fixation point toward a tactile stimulus delivered to one of the two hands, and switched between arms-crossed and arms-uncrossed postures every 6 trials. Trajectories were generally straight when the arms were uncrossed, but all participants made curved saccades when the arms were crossed (12–64%. We found that the probability of curved saccades depended critically on the onset latency: the probability was less than 5% when the latency was larger than 250 ms, but the probability increased up to 70–80% when the onset latency was 160 ms. This relationship was shared across participants. The results suggest that a touch in the arms-crossed posture was always mapped to the wrong hand in the initial phase up to 160 ms, and then remapped to the correct hand during the next 100 ms by some fundamental neural mechanisms shared across participants.

  3. A Journey Between Two Curves

    Directory of Open Access Journals (Sweden)

    Sergey A. Cherkis

    2007-03-01

    Full Text Available A typical solution of an integrable system is described in terms of a holomorphic curve and a line bundle over it. The curve provides the action variables while the time evolution is a linear flow on the curve's Jacobian. Even though the system of Nahm equations is closely related to the Hitchin system, the curves appearing in these two cases have very different nature. The former can be described in terms of some classical scattering problem while the latter provides a solution to some Seiberg-Witten gauge theory. This note identifies the setup in which one can formulate the question of relating the two curves.

  4. A test statistic in the complex Wishart distribution and its application to change detection in polarimetric SAR data

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Schou, Jesper

    2003-01-01

    . Based on this distribution, a test statistic for equality of two such matrices and an associated asymptotic probability for obtaining a smaller value of the test statistic are derived and applied successfully to change detection in polarimetric SAR data. In a case study, EMISAR L-band data from April 17...... to HH, VV, or HV data alone, the derived test statistic reduces to the well-known gamma likelihood-ratio test statistic. The derived test statistic and the associated significance value can be applied as a line or edge detector in fully polarimetric SAR data also....

  5. Spaceborne Polarimetric SAR Interferometry: Performance Analysis and Mission Concepts

    Directory of Open Access Journals (Sweden)

    Shane R. Cloude

    2005-12-01

    Full Text Available We investigate multichannel imaging radar systems employing coherent combinations of polarimetry and interferometry (Pol-InSAR. Such systems are well suited for the extraction of bio- and geophysical parameters by evaluating the combined scattering from surfaces and volumes. This combination leads to several important differences between the design of Pol-InSAR sensors and conventional single polarisation SAR interferometers. We first highlight these differences and then investigate the Pol-InSAR performance of two proposed spaceborne SAR systems (ALOS/PalSAR and TerraSAR-L operating in repeat-pass mode. For this, we introduce the novel concept of a phase tube which enables (1 a quantitative assessment of the Pol-InSAR performance, (2 a comparison between different sensor configurations, and (3 an optimization of the instrument settings for different Pol-InSAR applications. The phase tube may hence serve as an interface between system engineers and application-oriented scientists. The performance analysis reveals major limitations for even moderate levels of temporal decorrelation. Such deteriorations may be avoided in single-pass sensor configurations and we demonstrate the potential benefits from the use of future bi- and multistatic SAR interferometers.

  6. Spaceborne Polarimetric SAR Interferometry: Performance Analysis and Mission Concepts

    Science.gov (United States)

    Krieger, Gerhard; Papathanassiou, Konstantinos Panagiotis; Cloude, Shane R.

    2005-12-01

    We investigate multichannel imaging radar systems employing coherent combinations of polarimetry and interferometry (Pol-InSAR). Such systems are well suited for the extraction of bio- and geophysical parameters by evaluating the combined scattering from surfaces and volumes. This combination leads to several important differences between the design of Pol-InSAR sensors and conventional single polarisation SAR interferometers. We first highlight these differences and then investigate the Pol-InSAR performance of two proposed spaceborne SAR systems (ALOS/PalSAR and TerraSAR-L) operating in repeat-pass mode. For this, we introduce the novel concept of a phase tube which enables (1) a quantitative assessment of the Pol-InSAR performance, (2) a comparison between different sensor configurations, and (3) an optimization of the instrument settings for different Pol-InSAR applications. The phase tube may hence serve as an interface between system engineers and application-oriented scientists. The performance analysis reveals major limitations for even moderate levels of temporal decorrelation. Such deteriorations may be avoided in single-pass sensor configurations and we demonstrate the potential benefits from the use of future bi- and multistatic SAR interferometers.

  7. Discussion on Application of Polarimetric Synthetic Aperture Radar in Marine Surveillance

    Directory of Open Access Journals (Sweden)

    Zhang Jie

    2016-12-01

    Full Text Available Synthetic Aperture Radar (SAR, an important earth observation sensor, has been used in a wide range of applications for land and marine surveillance. Polarimetric SAR (PolSAR can obtain abundant scattering information of a target to improve the ability of target detection, classification, and quantitative inversion. In this paper, the important role of PolSAR in ocean monitoring is discussed with factors such as sea ice, ships, oil spill, waves, internal waves, and seabed topography. Moreover, the future development direction of PolSAR is put forward to get an inspiration for further research of PolSAR in marine surveillance applications.

  8. Processing and Analysis of Polarimetric Ship Signatures from MARSIE: Report on Results for Polar Epsilon

    Science.gov (United States)

    2006-10-01

    observations de la surface équivalente radar de navires cibles pour les canaux de copolarisation et de polarisation croisée, la réduction de la...motion, environmental conditions, etc. on the observed polarimetric signatures; • The differences in the elemental scatterer distributions among the...calculée pour plusieurs navires. Les valeurs estimées de SER totale pour les canaux HV et VH étaient d’environ 10 dB inférieures aux valeurs

  9. Fitting a Two-Component Scattering Model to Polarimetric SAR Data from Forests

    Science.gov (United States)

    Freeman, Anthony

    2007-01-01

    Two simple scattering mechanisms are fitted to polarimetric synthetic aperture radar (SAR) observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry and a ground scatter term that can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, which is seen through a layer of vertically oriented scatterers. The model is shown to represent the behavior of polarimetric backscatter from a tropical forest and two temperate forest sites by applying it to data from the National Aeronautic and Space Agency/Jet Propulsion Laboratory's Airborne SAR (AIRSAR) system. Scattering contributions from the two basic scattering mechanisms are estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. This model fit approach is justified as a simplification of more complicated scattering models, which require many inputs to solve the forward scattering problem. The model is used to develop an understanding of the ground-trunk double-bounce scattering that is present in the data, which is seen to vary considerably as a function of incidence angle. Two parameters in the model fit appear to exhibit sensitivity to vegetation canopy structure, which is worth further exploration. Results from the model fit for the ground scattering term are compared with estimates from a forward model and shown to be in good agreement. The behavior of the scattering from the ground-trunk interaction is consistent with the presence of a pseudo-Brewster angle effect for the air-trunk scattering interface. If the Brewster angle is known, it is possible to directly estimate the real part of the dielectric constant of the trunks, a key variable in forward modeling of backscatter from forests. It is also shown how, with a priori knowledge of the forest height, an estimate for the

  10. Soil Water Retention Curve

    Science.gov (United States)

    Johnson, L. E.; Kim, J.; Cifelli, R.; Chandra, C. V.

    2016-12-01

    Potential water retention, S, is one of parameters commonly used in hydrologic modeling for soil moisture accounting. Physically, S indicates total amount of water which can be stored in soil and is expressed in units of depth. S can be represented as a change of soil moisture content and in this context is commonly used to estimate direct runoff, especially in the Soil Conservation Service (SCS) curve number (CN) method. Generally, the lumped and the distributed hydrologic models can easily use the SCS-CN method to estimate direct runoff. Changes in potential water retention have been used in previous SCS-CN studies; however, these studies have focused on long-term hydrologic simulations where S is allowed to vary at the daily time scale. While useful for hydrologic events that span multiple days, the resolution is too coarse for short-term applications such as flash flood events where S may not recover its full potential. In this study, a new method for estimating a time-variable potential water retention at hourly time-scales is presented. The methodology is applied for the Napa River basin, California. The streamflow gage at St Helena, located in the upper reaches of the basin, is used as the control gage site to evaluate the model performance as it is has minimal influences by reservoirs and diversions. Rainfall events from 2011 to 2012 are used for estimating the event-based SCS CN to transfer to S. As a result, we have derived the potential water retention curve and it is classified into three sections depending on the relative change in S. The first is a negative slope section arising from the difference in the rate of moving water through the soil column, the second is a zero change section representing the initial recovery the potential water retention, and the third is a positive change section representing the full recovery of the potential water retention. Also, we found that the soil water moving has traffic jam within 24 hours after finished first

  11. Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations

    Science.gov (United States)

    Bolen, Steve; Chandrasekar, V.

    2002-01-01

    Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for

  12. POLARIMETRIC DETECTION OF EXOPLANETS TRANSITING T AND L BROWN DWARFS

    International Nuclear Information System (INIS)

    Sengupta, Sujan

    2016-01-01

    While scattering of light by atoms and molecules yields large amounts of polarization at the B-band of both T and L dwarfs, scattering by dust grains in the cloudy atmosphere of L dwarfs gives rise to significant polarization at the far-optical and infrared wavelengths where these objects are much brighter. However, the observable disk-averaged polarization should be zero if the clouds are uniformly distributed and the object is spherically symmetric. Therefore, in order to explain the observed large polarization of several L dwarfs, rotation-induced oblateness or horizontally inhomogeneous cloud distribution in the atmosphere is invoked. On the other hand, when an extra-solar planet of Earth-size or larger transits the brown dwarf along the line of sight, the asymmetry induced during the transit gives rise to a net non-zero, time-dependent polarization. Employing atmospheric models for a range of effective temperature and surface gravity appropriate for T and L dwarfs, I derive the time-dependent polarization profiles of these objects during the transit phase and estimate the peak amplitude of polarization that occurs during the inner contact points of the transit ingress/egress phase. It is found that peak polarization in the range of 0.2%–1.0% at I and J band may arise of cloudy L dwarfs occulted by Earth-size or larger exoplanets. Such an amount of polarization is higher than what can be produced by rotation-induced oblateness of even rapidly rotating L dwarfs. Hence, I suggest that time-resolved imaging polarization could be a potential technique for detecting transiting exoplanets around L dwarfs.

  13. POLARIMETRIC DETECTION OF EXOPLANETS TRANSITING T AND L BROWN DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Sujan, E-mail: sujan@iiap.res.in [Indian Institute of Astrophysics, Koramangala 2nd Block, Bangalore 560 034 (India)

    2016-10-01

    While scattering of light by atoms and molecules yields large amounts of polarization at the B-band of both T and L dwarfs, scattering by dust grains in the cloudy atmosphere of L dwarfs gives rise to significant polarization at the far-optical and infrared wavelengths where these objects are much brighter. However, the observable disk-averaged polarization should be zero if the clouds are uniformly distributed and the object is spherically symmetric. Therefore, in order to explain the observed large polarization of several L dwarfs, rotation-induced oblateness or horizontally inhomogeneous cloud distribution in the atmosphere is invoked. On the other hand, when an extra-solar planet of Earth-size or larger transits the brown dwarf along the line of sight, the asymmetry induced during the transit gives rise to a net non-zero, time-dependent polarization. Employing atmospheric models for a range of effective temperature and surface gravity appropriate for T and L dwarfs, I derive the time-dependent polarization profiles of these objects during the transit phase and estimate the peak amplitude of polarization that occurs during the inner contact points of the transit ingress/egress phase. It is found that peak polarization in the range of 0.2%–1.0% at I and J band may arise of cloudy L dwarfs occulted by Earth-size or larger exoplanets. Such an amount of polarization is higher than what can be produced by rotation-induced oblateness of even rapidly rotating L dwarfs. Hence, I suggest that time-resolved imaging polarization could be a potential technique for detecting transiting exoplanets around L dwarfs.

  14. Intersection numbers of spectral curves

    CERN Document Server

    Eynard, B

    2011-01-01

    We compute the symplectic invariants of an arbitrary spectral curve with only 1 branchpoint in terms of integrals of characteristic classes in the moduli space of curves. Our formula associates to any spectral curve, a characteristic class, which is determined by the laplace transform of the spectral curve. This is a hint to the key role of Laplace transform in mirror symmetry. When the spectral curve is y=\\sqrt{x}, the formula gives Kontsevich--Witten intersection numbers, when the spectral curve is chosen to be the Lambert function \\exp{x}=y\\exp{-y}, the formula gives the ELSV formula for Hurwitz numbers, and when one chooses the mirror of C^3 with framing f, i.e. \\exp{-x}=\\exp{-yf}(1-\\exp{-y}), the formula gives the topological vertex formula, i.e. the generating function of Gromov-Witten invariants of C^3. In some sense this formula generalizes ELSV formula, and Mumford formula.

  15. Optimization on Spaces of Curves

    DEFF Research Database (Denmark)

    Møller-Andersen, Jakob

    This thesis is concerned with computational and theoretical aspects of Riemannian metrics on spaces of regular curves, and their applications. It was recently proved that second order constant coefficient Sobolev metrics on curves are geodesically complete. We extend this result to the case...... of Sobolev metrics with coefficient functions depending on the length of the curve. We show how to apply this result to analyse a wide range of metrics on the submanifold of unit and constant speed curves. We present a numerical discretization of second order Sobolev metrics on the space of regular curves...... of cardiac deformations. Finally we investigate a new application of Riemannian shape analysis in shape optimization. We setup a simple elliptic model problem, and describe how to apply shape calculus to obtain directional derivatives in the manifold of planar curves. We present an implementation based...

  16. Validation of Forested Inundation Extent Revealed by L-Band Polarimetric and Interferometric SAR Data

    Science.gov (United States)

    Chapman, Bruce; Celi, Jorge; Hamilton, Steve; McDonald, Kyle

    2013-01-01

    UAVSAR, NASA's airborne Synthetic Aperture Radar (SAR), conducted an extended observational campaign in Central and South America in March 2013, primarily related to volcanic deformations along the Andean Mountain Range but also including a large number of flights studying other scientific phenomena. During this campaign, the L-Band SAR collected data over the Napo River in Ecuador. The objectives of this experiment were to acquire polarimetric and interferometric L-Band SAR data over an inundated tropical forest in Ecuador simultaneously with on-the-ground field work ascertaining the extent of inundation, and to then derive from this data a quantitative estimate for the error in the SAR-derived inundation extent. In this paper, we will first describe the processing and preliminary analysis of the SAR data. The polarimetric SAR data will be classified by land cover and inundation state. The interferometric SAR data will be used to identify those areas where change in inundation extent occurred, and to measure the change in water level between two observations separated by a week. Second, we will describe the collection of the field estimates of inundation, and have preliminary comparisons of inundation extent measured in the field field versus that estimated from the SAR data.

  17. Full polarimetric millimetre wave radar for stand-off security screening

    Science.gov (United States)

    Blackhurst, Eddie; Salmon, Neil; Southgate, Matthew

    2017-10-01

    The development and measurements are described of a frequency modulated continuous wave (FMCW) mono-static millimetre wave full polarimetric radar, operating at k-band (18 to 26 GHz). The system has been designed to explore the feasibility of using full polarimetry for the detection of concealed weapons, and person borne improvised explosive devices (PBIED). The philosophy of this scheme is a means to extract the maximum information content from a target which is normally in the single spatial pixel (sometimes sub-pixel) configuration in stand-off (tens of metres) and crowd surveillance scenarios. The radar comprises a vector network analyser (VNA), an orthomode transducer and a conical horn antenna. A calibration strategy is discussed and demonstrated using a variety of known calibration targets with known reflective properties, including a flat metal plate, dihedral reflector, metal sphere, helix and dipole. The orthomode transducer is based on a high performance linear polarizer of the turnstile type with isolation better than - 35dB between orthogonal polarisations. The calibration enables the polarimetric Sinclair scattering matrix to be measured at each frequency for coherent polarimetry, and this can be extended using multiple measurements via the Kennaugh matrix to investigate incoherent full polarimetry.

  18. Handheld SFDI/polarimetric imaging device for objective evaluation of hypertrophic scars (Conference Presentation)

    Science.gov (United States)

    Ramella-Roman, Jessica C.; Montejo, Karla; Sevilla, Nicole; Stoff, Susan; Gonzalez, Mariacarla; Chue-Sang, Joseph

    2017-02-01

    Scars can be debilitating and cause serious functional limitations, significantly reduced physical function and loss of ability to perform normal daily activities. Scar formation is not fully understood and the treatment options have been hampered by the lack of an objective diagnostic tool to assess scars. Presently, assessment of hypertrophic scars has been based on subjective clinician rankings using a four-parameter scale called the Vancouver Scar Scale (VSS) or the Patient Observer Scar Assessment Scale (POSAS) but no objective, standardized tool for quantifying scar severity is available, despite known inadequacies of the subjective scales. We have developed a hand-held multi modal system consisting of a combined Spatial Frequency Domain Imager (SFDI) used for the assessment of tissue molecular components and a polarimeter for structural measurements. The SFDI capability is provided by an Arduino board controlled spectrally and polarimetric diverse Light Emitting Diodes (LED) ring illuminator. For SFDI imagery, the LEDs are combined with sinusoidal patterns. A single pattern snapshot SFDI approach is used to observe and quantify the biological components in the scar tissue including: oxygenated and de oxygenated hemoglobin, water, and melanin. The SFDI system is integrated with a reduced Mueller Matrix polarimetric system, whose illumination is also included in the LED's ring, and providing for the assessment of collagen orientation through Mueller Matrix decomposition. The design of the system and experimental work on phantoms will be presented.

  19. Polarimetric Imaging Of Protoplanetary Disks From The Optical To Sub-Mm

    Science.gov (United States)

    De Boer, Jos; Ménard, F.; Pinte, C.; van der Plas, G.; Snik, F.

    2017-10-01

    To learn how planets form from the smallest building blocks within protoplanetary disks, we first need to know how dust grains grow from micron to mm sizes. Polarimetry across the spectrum has proven to be sensitive to grain properties like dust size distribution and composition and thus can be used to characterize the scattering grains. However, polarization measured with radio interferometric arrays is rarely studied in concert with optical polarimetry. Our team has successfully calibrated the NIR polarimetric imaging mode of VLT/SPHERE, hence upgrading the instrument from a high-contrast imager to a robust tool for quantitative characterization. In this presentation, we will discuss which lessons can be learned by comparing polarimetry in the optical and sub-mm and explore for which science cases both techniques can complement each other. When we combine the polarimetric capabilities of the most advanced optical high-contrast imagers (e.g., Gemini GPI or VLT SPHERE) with that of ALMA we will be able to study the spatial distribution of an extensive range of different grains, which allows us to take an essential step towards a deeper understanding of planet formation.

  20. Algorithm Development for the Optimum Rainfall Estimation Using Polarimetric Variables in Korea

    Directory of Open Access Journals (Sweden)

    Cheol-Hwan You

    2015-01-01

    Full Text Available In this study, to get an optimum rainfall estimation using polarimetric variables observed from Bislsan radar which is the first polarimetric radar in Korea, rainfall cases for 84 hours caused by different conditions, which are Changma front and typhoon, Changma front only, and typhoon only, occurred in 2011, were analyzed. And rainfall algorithms were developed by using long period drop size distributions with six different raindrop axis ratio relations. The combination of the relations between R and Z, ZDR, R and KDP, ZDR, and R and KDP with different rainfall intensity would be an optimum rainfall algorithm if the reference of rainfall would be defined correctly. In the case the reference is not defined adequately, the relation between R and Z, ZDR, KDP, AH and R and Z, KDP, AH can be used as a representative rainfall relation. Particularly if the qualified ZDR is not available, the relation between R and Z, KDP, AH can be used as an optimum rainfall relation in Korea.

  1. Landslide Mapping in Vegetated Areas Using Change Detection Based on Optical and Polarimetric SAR Data

    Directory of Open Access Journals (Sweden)

    Simon Plank

    2016-04-01

    Full Text Available Mapping of landslides, quickly providing information about the extent of the affected area and type and grade of damage, is crucial to enable fast crisis response, i.e., to support rescue and humanitarian operations. Most synthetic aperture radar (SAR data-based landslide detection approaches reported in the literature use change detection techniques, requiring very high resolution (VHR SAR imagery acquired shortly before the landslide event, which is commonly not available. Modern VHR SAR missions, e.g., Radarsat-2, TerraSAR-X, or COSMO-SkyMed, do not systematically cover the entire world, due to limitations in onboard disk space and downlink transmission rates. Here, we present a fast and transferable procedure for mapping of landslides, based on change detection between pre-event optical imagery and the polarimetric entropy derived from post-event VHR polarimetric SAR data. Pre-event information is derived from high resolution optical imagery of Landsat-8 or Sentinel-2, which are freely available and systematically acquired over the entire Earth’s landmass. The landslide mapping is refined by slope information from a digital elevation model generated from bi-static TanDEM-X imagery. The methodology was successfully applied to two landslide events of different characteristics: A rotational slide near Charleston, West Virginia, USA and a mining waste earthflow near Bolshaya Talda, Russia.

  2. Development and Testing of Operational Dual-Polarimetric Radar Based Lightning Initiation Forecast Techniques

    Science.gov (United States)

    Woodard, Crystal; Carey, Lawrence D.; Petersen, Walter A.; Felix, Mariana; Roeder, William P.

    2011-01-01

    Lightning is one of Earth s natural dangers, destructive not only to life but also physical property. According to the National Weather Service, there are on average 58 lightning fatalities each year, with over 300 related injuries (NWS 2010). The ability to forecast lightning is critical to a host of activities ranging from space vehicle launch operations to recreational sporting events. For example a single lightning strike to a Space Shuttle could cause billions of dollars of damage and possible loss of life. While forecasting that provides longer lead times could provide sporting officials with more time to respond to possible threatening weather events, thus saving the lives of player and bystanders. Many researchers have developed and tested different methods and tools of first flash forecasting, however few have done so using dual-polarimetric radar variables and products on an operational basis. The purpose of this study is to improve algorithms for the short-term prediction of lightning initiation through development and testing of operational techniques that rely on parameters observed and diagnosed using C-band dual-polarimetric radar.

  3. Decomposition of Polarimetric SAR Images Based on Second- and Third-order Statics Analysis

    Science.gov (United States)

    Kojima, S.; Hensley, S.

    2012-12-01

    There are many papers concerning the research of the decomposition of polerimetric SAR imagery. Most of them are based on second-order statics analysis that Freeman and Durden [1] suggested for the reflection symmetry condition that implies that the co-polarization and cross-polarization correlations are close to zero. Since then a number of improvements and enhancements have been proposed to better understand the underlying backscattering mechanisms present in polarimetric SAR images. For example, Yamaguchi et al. [2] added the helix component into Freeman's model and developed a 4 component scattering model for the non-reflection symmetry condition. In addition, Arii et al. [3] developed an adaptive model-based decomposition method that could estimate both the mean orientation angle and a degree of randomness for the canopy scattering for each pixel in a SAR image without the reflection symmetry condition. This purpose of this research is to develop a new decomposition method based on second- and third-order statics analysis to estimate the surface, dihedral, volume and helix scattering components from polarimetric SAR images without the specific assumptions concerning the model for the volume scattering. In addition, we evaluate this method by using both simulation and real UAVSAR data and compare this method with other methods. We express the volume scattering component using the wire formula and formulate the relationship equation between backscattering echo and each component such as the surface, dihedral, volume and helix via linearization based on second- and third-order statics. In third-order statics, we calculate the correlation of the correlation coefficients for each polerimetric data and get one new relationship equation to estimate each polarization component such as HH, VV and VH for the volume. As a result, the equation for the helix component in this method is the same formula as one in Yamaguchi's method. However, the equation for the volume

  4. Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar

    Science.gov (United States)

    Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

    2010-05-01

    Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and

  5. Reflection of curved shock waves

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.

  6. VizieR Online Data Catalog: Main-belt asteroids polarimetric survey. II. (Gil-Hutton+, 2012)

    Science.gov (United States)

    Gil-Hutton, R.; Canada-Assandri, M.

    2012-01-01

    Results for the objects observed during the polarimetric survey of main-belt asteroids. The observations were carried out during different observing runs between May 2004 and November 2009 at the 2.15m telescope of the CASLEO, San Juan, Argentina, using the Torino and CASPROF polarimeters. (3 data files).

  7. Use of Radarsat-2 polarimetric SAR images for fuel moisture mapping in the Kruger National Park, South Africa

    CSIR Research Space (South Africa)

    Kong, M

    2015-08-01

    Full Text Available Fully polarimetric Radarsat-2 imagery from wet and dry conditions over the South African Lowveld is compared to assess its value for fuel moisture mapping. Imagery was acquired at two different dates, in May (end of summer, wet) and in August (mid...

  8. Basics and first experiments demonstrating isolation improvements in the agile polarimetric FM-CW radar – PARSAX

    NARCIS (Netherlands)

    Krasnov, O.A.; Babur, G.P.; Wang, Z.; Ligthart, L.P.; Van der Zwan, F.

    2010-01-01

    The article describes the IRCTR PARSAX radar system, the S-band high-resolution Doppler polarimetric frequency modulated continuous wave (FM-CW) radar with dual-orthogonal sounding signals, which has the possibility to measure all elements of the radar target polarization scattering matrix

  9. High-resolution polarimetric X-band weather radar observations at the Cabauw Experimental Site for Atmospheric Research

    NARCIS (Netherlands)

    Otto, T.; Russchenberg, H.W.J.

    2013-01-01

    In 2007, the horizontally scanning polarimetric X-band radar IDRA (IRCTR Drizzle Radar) was installed on top of the 213 m high mast at the Dutch meteorological observatory Cabauw Experimental Site for Atmospheric Research (CESAR) at Netherlands. This radar complements a large variety of measurement

  10. Clustering of Multi-Temporal Fully Polarimetric L-Band SAR Data for Agricultural Land Cover Mapping

    Science.gov (United States)

    Tamiminia, H.; Homayouni, S.; Safari, A.

    2015-12-01

    Recently, the unique capabilities of Polarimetric Synthetic Aperture Radar (PolSAR) sensors make them an important and efficient tool for natural resources and environmental applications, such as land cover and crop classification. The aim of this paper is to classify multi-temporal full polarimetric SAR data using kernel-based fuzzy C-means clustering method, over an agricultural region. This method starts with transforming input data into the higher dimensional space using kernel functions and then clustering them in the feature space. Feature space, due to its inherent properties, has the ability to take in account the nonlinear and complex nature of polarimetric data. Several SAR polarimetric features extracted using target decomposition algorithms. Features from Cloude-Pottier, Freeman-Durden and Yamaguchi algorithms used as inputs for the clustering. This method was applied to multi-temporal UAVSAR L-band images acquired over an agricultural area near Winnipeg, Canada, during June and July in 2012. The results demonstrate the efficiency of this approach with respect to the classical methods. In addition, using multi-temporal data in the clustering process helped to investigate the phenological cycle of plants and significantly improved the performance of agricultural land cover mapping.

  11. An omnibus likelihood test statistic and its factorization for change detection in time series of polarimetric SAR data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2016-01-01

    Based on an omnibus likelihood ratio test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution with an associated p-value and a factorization of this test statistic, change analysis in a short sequence of multilook, polarimetric SAR data...

  12. Comparison of vehicle-mounted forward-looking polarimetric infrared and downward-looking infrared sensors for landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Schavemaker, J.G.M.; Jong, W. de; Schutte, K.

    2003-01-01

    This paper gives a comparison of two vehicle-mounted infrared systems for landmine detection. The first system is a down-ward looking standard infrared camera using processing methods developed within the EU project LOTUS. The second system is using a forward-looking polarimetric infrared camera.

  13. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    International Nuclear Information System (INIS)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-01-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  14. Polarimetric SAR tomography in the X-band by continuous wave multi-baseline SAR tracks in a convex optimization approach

    Science.gov (United States)

    Biondi, Filippo; Sarri, Antonio; Fiori, Luca; Dell'Omodarme, Kevin

    2014-10-01

    SAR Tomography is the extension of the conventional interferometric radar signal processing, extended in the height dimension. In order to improve the vertical resolution with respect to the classical Fourier methods, high resolution approaches, based on the Convex Optimization (CVX), has been implemented. This methods recast in the Compressed Sensing (CS) framework that optimize tomographic smooth profiles via atomic decomposition, in order to obtain sparsity. The optimum solution has been estimated by Interior Point Methods (IPM). The problem for such kind of signal processing is that the tomographic phase information may be suppressed and only the optimized energy information is available. In this paper we propose a method in order to estimate an optimized spectra and phase information projecting each vector components of each tomographic resolution cell spanned in the real and the imaginary component. The tomographic solutions has been performed by processing multi-baseline SAR datasets, in a full polarimetric mode, acquired by a portable small Continuous Wave (CW) radar in the X band.

  15. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    Science.gov (United States)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-08-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  16. On the Use of Generalized Volume Scattering Models for the Improvement of General Polarimetric Model-Based Decomposition

    Directory of Open Access Journals (Sweden)

    Qinghua Xie

    2017-01-01

    Full Text Available Recently, a general polarimetric model-based decomposition framework was proposed by Chen et al., which addresses several well-known limitations in previous decomposition methods and implements a simultaneous full-parameter inversion by using complete polarimetric information. However, it only employs four typical models to characterize the volume scattering component, which limits the parameter inversion performance. To overcome this issue, this paper presents two general polarimetric model-based decomposition methods by incorporating the generalized volume scattering model (GVSM or simplified adaptive volume scattering model, (SAVSM proposed by Antropov et al. and Huang et al., respectively, into the general decomposition framework proposed by Chen et al. By doing so, the final volume coherency matrix structure is selected from a wide range of volume scattering models within a continuous interval according to the data itself without adding unknowns. Moreover, the new approaches rely on one nonlinear optimization stage instead of four as in the previous method proposed by Chen et al. In addition, the parameter inversion procedure adopts the modified algorithm proposed by Xie et al. which leads to higher accuracy and more physically reliable output parameters. A number of Monte Carlo simulations of polarimetric synthetic aperture radar (PolSAR data are carried out and show that the proposed method with GVSM yields an overall improvement in the final accuracy of estimated parameters and outperforms both the version using SAVSM and the original approach. In addition, C-band Radarsat-2 and L-band AIRSAR fully polarimetric images over the San Francisco region are also used for testing purposes. A detailed comparison and analysis of decomposition results over different land-cover types are conducted. According to this study, the use of general decomposition models leads to a more accurate quantitative retrieval of target parameters. However, there

  17. Regular homotopy of Hurwitz curves

    International Nuclear Information System (INIS)

    Auroux, D; Kulikov, Vik S; Shevchishin, V V

    2004-01-01

    We prove that any two irreducible cuspidal Hurwitz curves C 0 adn C 1 (or, more generally, two curves with A-type singularities) in the Hirzebruch surface F N with the same homology classes and sets of singularities are regular homotopic. Moreover, they are symplectically regular homotopic if C 0 and C 1 are symplectic with respect to a compatible symplectic form

  18. Space curves, anholonomy and nonlinearity

    Indian Academy of Sciences (India)

    Walker parallel transport [14] of any vector P moved ... of Fermi–Walker parallel transport to the case of a moving space curve. 4. General curve evolution equations .... ear term of the Lamb equation (eq. (34)) is just the time derivative of the total.

  19. Localized qubits in curved spacetimes

    Science.gov (United States)

    Palmer, Matthew C.; Takahashi, Maki; Westman, Hans F.

    2012-04-01

    We provide a systematic and self-contained exposition of the subject of localized qubits in curved spacetimes. This research was motivated by a simple experimental question: if we move a spatially localized qubit, initially in a state |ψ1>, along some spacetime path Γ from a spacetime point x1 to another point x2, what will the final quantum state |ψ2> be at point x2? This paper addresses this question for two physical realizations of the qubit: spin of a massive fermion and polarization of a photon. Our starting point is the Dirac and Maxwell equations that describe respectively the one-particle states of localized massive fermions and photons. In the WKB limit we show how one can isolate a two-dimensional quantum state which evolves unitarily along Γ. The quantum states for these two realizations are represented by a left-handed 2-spinor in the case of massive fermions and a four-component complex polarization vector in the case of photons. In addition we show how to obtain from this WKB approach a fully general relativistic description of gravitationally induced phases. We use this formalism to describe the gravitational shift in the Colella-Overhauser-Werner 1975 experiment. In the non-relativistic weak field limit our result reduces to the standard formula in the original paper. We provide a concrete physical model for a Stern-Gerlach measurement of spin and obtain a unique spin operator which can be determined given the orientation and velocity of the Stern-Gerlach device and velocity of the massive fermion. Finally, we consider multipartite states and generalize the formalism to incorporate basic elements from quantum information theory such as quantum entanglement, quantum teleportation, and identical particles. The resulting formalism provides a basis for exploring precision quantum measurements of the gravitational field using techniques from quantum information theory.

  20. A New Polarimetric Study of Cygnus A Using JVLA from 2-18GHz

    Science.gov (United States)

    Lerato Sebokolodi, Makhuduga; Perley, Rick; Carilli, Chris; Smirnov, Oleg M.; Makhathini, Sphesihle

    2018-01-01

    Polarimetric studies of Cygnus A [5, 1, 2, 3] have shown that this radio galaxy has unusually large rotation measures ranging from -4000 to +3000 rad m -2 for the eastern lobe (E-lobe) and -2000 to +1300 rad m -2 for western lobe(W-lobe). A challenge since then has been to identify the medium(s) responsible for these high Faraday rotations (FR). Although a majority of the FR must arise from the surrounding cluster gas, an unknown portion may arise either in the sheath or within the lobes. In these cases, some depolarization must result, along with a non λ 2 rotation of the plane of polarization. Detecting such a depolarization will enable an estimate of the internal (and/or sheath) thermal gas density. [1] found significant depolarization associated with the inner regions of the E-lobe and no depolarization associated with the W-lobe. This depolarization could be either internal to the source (Faraday depolarization) or due to unresolved small-scale fluctuations in the foreground screen (beam depolarization) [1]. The former is expected to impose significant deviations in the λ2 -law, none of which have been found to date, nor could have been found due to the limited number of frequencies employed in these studies.Since 2015, new JVLA polarimetric observations of Cygnus A have been taken, in all four configurations, covering the frequency range from 2 to 18GHz. These new data provide thousands of frequency channels at high resolution and sensitivity – opening a new opportunity to study in great detail the physics of the jets, lobes and the magnetic field of the X-ray cluster medium and lobes. Our objective is to analyze these new polarimetric data with the expectation of extending the previous work and more importantly, to investigate the possibility of any significantdeviations from the λ2-law. Initial analysis shows significant deviations from λ2 -law associated with the W-lobe. We will present these results in detail, and also the results from RM

  1. Efficient Estimation of Spectral Moments and the Polarimetric Variables on Weather Radars, Sonars, Sodars, Acoustic Flow Meters, Lidars, and Similar Active Remote Sensing Instruments

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method for estimation of Doppler spectrum, its moments, and polarimetric variables on pulsed weather radars which uses over sampled echo components at a rate...

  2. GHRSST Level 3U Global Subskin Sea Surface Temperature from the WindSat Polarimetric Radiometer on the Coriolis satellite (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The WindSat Polarimetric Radiometer, launched on January 6, 2003 aboard the Department of Defense Coriolis satellite, was designed to measure the ocean surface wind...

  3. Computational aspects of algebraic curves

    CERN Document Server

    Shaska, Tanush

    2005-01-01

    The development of new computational techniques and better computing power has made it possible to attack some classical problems of algebraic geometry. The main goal of this book is to highlight such computational techniques related to algebraic curves. The area of research in algebraic curves is receiving more interest not only from the mathematics community, but also from engineers and computer scientists, because of the importance of algebraic curves in applications including cryptography, coding theory, error-correcting codes, digital imaging, computer vision, and many more.This book cove

  4. CYCLING CURVES AND THEIR APPLICATIONS

    Directory of Open Access Journals (Sweden)

    RAICU Lucian

    2015-06-01

    Full Text Available This paper proposes an analysis of the cyclic curves that can be considered as some of the most important regarding their applications in science, technique, design, architecture and art. These curves include the following: cycloid, epicycloid, hypocycloid, spherical cycloid and special cases thereof. In the first part of the paper the main curves of cycloids family are presented with their methods of generating and setting parametric equations. In the last part some of cycloid applications are highlighted in different areas of science, technology and art.

  5. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    Science.gov (United States)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  6. PRELIMINARY RESULTS OF ESTIMATING SOIL MOISTURE OVER BARE SOIL USING FULL-POLARIMETRIC ALOS-2 DATA

    Directory of Open Access Journals (Sweden)

    A. Sekertekin

    2016-10-01

    Full Text Available Synthetic Aperture Radar (SAR imaging system is one of the most effective way for Earth observation. The aim of this study is to present the preliminary results about estimating soil moisture using L-band Synthetic Aperture Radar (SAR data. Full-polarimetric (HH, HV, VV, VH ALOS-2 data, acquired on 22.04.2016 with the incidence angle of 30.4o, were used in the study. Simultaneously with the SAR acquisition, in-situ soil moisture samples over bare agricultural lands were collected and evaluated using gravimetric method. Backscattering coefficients for all polarizations were obtained and linear regression analysis was carried out with in situ moisture measurements. The best correlation coefficient was observed with VV polarization. Cross-polarized backscattering coefficients were not so sensitive to soil moisture content. In the study, it was observed that soil moisture maps can be retrieved with the accuracy about 14% (RMSE.

  7. Bilateral bad pixel and Stokes image reconstruction for microgrid polarimetric imagers

    Science.gov (United States)

    LeMaster, Daniel A.; Ratliff, Bradley M.

    2015-09-01

    Uncorrected or poorly corrected bad pixels reduce the effectiveness of polarimetric clutter suppression. In conventional microgrid processing, bad pixel correction is accomplished as a separate step from Stokes image reconstruction. Here, these two steps are combined to speed processing and provide better estimates of the entire image, including missing samples. A variation on the bilateral filter enables both edge preservation in the Stokes imagery and bad pixel suppression. Understanding the newly presented filter requires two key insights. First, the adaptive nature of the bilateral filter is extended to correct for bad pixels by simply incorporating a bad pixel mask. Second, the bilateral filter for Stokes estimation is the sum of the normalized bilateral filters for estimating each analyzer channel individually. This paper describes the new approach and compares it to our legacy method using simulated imagery.

  8. Space-based detection of space debris by photometric and polarimetric characteristics

    Science.gov (United States)

    Pang, Shuxia; Wang, Hu; Lu, Xiaoyun; Shen, Yang; Pan, Yue

    2017-10-01

    The number of space debris has been increasing dramatically in the last few years, and is expected to increase as much in the future. As the orbital debris population grows, the risk of collision between debris and other orbital objects also grows. Therefore, space debris detection is a particularly important task for space environment security, and then supports for space debris modeling, protection and mitigation. This paper aims to review space debris detection systematically and completely. Firstly, the research status of space debris detection at home and abroad is presented. Then, three kinds of optical observation methods of space debris are summarized. Finally, we propose a space-based detection scheme for space debris by photometric and polarimetric characteristics.

  9. Synergy of optical and polarimetric microwave data for forest resource assessment

    International Nuclear Information System (INIS)

    Miguel-Ayanz, J.S.

    1997-01-01

    Data acquired during the Mac-Europe 91 campaign over the Black Forest ( Germany) are used to study the synergy of optical imaging spectrometer data ( AVIRIS) and polarimetric microwave data ( AIRSAR) for forest resource assessment. Original and new derived bands from AIRSAR and AVIRIS data are used to predict age and biomass. The best predictors ( bands) are selected through a multivariate stepwise regression analysis of each of the datasets separately. Then the joint AIRSAR-AVIRIS dataset is analysed. This study shows how the synergistic use of AIRSAR and AVIRIS data improves significantly the predictions obtained from the individual datasets for both age and biomass over the test site. In the analysis of AVIRIS data a new approach for processing large datasets as those provided by imaging spectrometers is presented, so that maximum likelihood classification of these datasets becomes feasible. (author)

  10. Semi-supervised Learning for Classification of Polarimetric SAR Images Based on SVM-Wishart

    Directory of Open Access Journals (Sweden)

    Hua Wen-qiang

    2015-02-01

    Full Text Available In this study, we propose a new semi-supervised classification method for Polarimetric SAR (PolSAR images, aiming at handling the issue that the number of train set is small. First, considering the scattering characters of PolSAR data, this method extracts multiple scattering features using target decomposition approach. Then, a semi-supervised learning model is established based on a co-training framework and Support Vector Machine (SVM. Both labeled and unlabeled data are utilized in this model to obtain high classification accuracy. Third, a recovery scheme based on the Wishart classifier is proposed to improve the classification performance. From the experiments conducted in this study, it is evident that the proposed method performs more effectively compared with other traditional methods when the number of train set is small.

  11. ESA'S POLarimetric Airborne Radar Ice Sounder (POLARIS): design and first results

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kristensen, Steen Savstrup; Krozer, Viktor

    2010-01-01

    -of-concept campaign was conducted in Greenland. This study outlines the design and implementation of the system, and based on first results it is concluded that in the central dry snow zone of Greenland, POLARIS can resolve shallow and deep internal ice layers, penetrate the thickest ice encountered and detect......The Technical University of Denmark has developed and tested a P-band ice sounding radar for European Space Agency (ESA). With the recent by the International Telecommunication Union (ITU) allocation of a radar band at 435 MHz, increased interest in space-based sounding of the Earth s ice caps has...... been encountered. ESA s POLarimetric Airborne Radar Ice Sounder (POLARIS) is intended to provide a better understanding of P-band scattering and propagation through ice sheets and to verify novel surface clutter suppression techniques in preparation for a potential space-based ice sounding mission...

  12. EMISAR: An Absolutely Calibrated Polarimetric L- and C-band SAR

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Skou, Niels; Dall, Jørgen

    1998-01-01

    and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry. Thermal control and several calibration loops have been built into the system to ensure system stability and absolute......EMISAR is a high-resolution (2×2 m), fully polarimetric, dual-frequency (L- and C-band) synthetic aperture radar (SAR) system designed for remote-sensing applications. The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes...... calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key to most of the current applications. Recent interferometric enhancements are important for many scientific applications...

  13. Oil detection in a coastal marsh with polarimetric Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Suzuoki, Yukihiro; Jones, Cathleen E.

    2011-01-01

    The National Aeronautics and Space Administration's airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR) sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  14. Oil Detection in a Coastal Marsh with Polarimetric Synthetic Aperture Radar (SAR

    Directory of Open Access Journals (Sweden)

    Cathleen E. Jones

    2011-12-01

    Full Text Available The National Aeronautics and Space Administration’s airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD and Cloude-Pottier (CP decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  15. QuadCam - A Quadruple Polarimetric Camera for Space Situational Awareness

    Science.gov (United States)

    Skuljan, J.

    A specialised quadruple polarimetric camera for space situational awareness, QuadCam, has been built at the Defence Technology Agency (DTA), New Zealand, as part of collaboration with the Defence Science and Technology Laboratory (Dstl), United Kingdom. The design was based on a similar system originally developed at Dstl, with some significant modifications for improved performance. The system is made up of four identical CCD cameras looking in the same direction, but in a different plane of polarisation at 0, 45, 90 and 135 degrees with respect to the reference plane. A standard set of Stokes parameters can be derived from the four images in order to describe the state of polarisation of an object captured in the field of view. The modified design of the DTA QuadCam makes use of four small Raspberry Pi computers, so that each camera is controlled by its own computer in order to speed up the readout process and ensure that the four individual frames are taken simultaneously (to within 100-200 microseconds). In addition, a new firmware was requested from the camera manufacturer so that an output signal is generated to indicate the state of the camera shutter. A specialised GPS unit (also developed at DTA) is then used to monitor the shutter signals from the four cameras and record the actual time of exposure to an accuracy of about 100 microseconds. This makes the system well suited for the observation of fast-moving objects in the low Earth orbit (LEO). The QuadCam is currently mounted on a Paramount MEII robotic telescope mount at the newly built DTA space situational awareness observatory located on Whangaparaoa Peninsula near Auckland, New Zealand. The system will be used for tracking satellites in low Earth orbit and geostationary belt as well. The performance of the camera has been evaluated and a series of test images have been collected in order to derive the polarimetric signatures for selected satellites.

  16. Portable polarimetric fiber stress sensor system for visco-elastic and biomimetic material analysis

    Science.gov (United States)

    Harrison, Mark C.; Armani, Andrea M.

    2015-05-01

    Non-destructive materials characterization methods have significantly changed our fundamental understanding of material behavior and have enabled predictive models to be developed. However, the majority of these efforts have focused on crystalline and metallic materials, and transitioning to biomaterials, such as tissue samples, is non-trivial, as there are strict sample handling requirements and environmental controls which prevent the use of conventional equipment. Additionally, the samples are smaller and more complex in composition. Therefore, more advanced sample analysis methods capable of operating in these environments are needed. In the present work, we demonstrate an all-fiber-based material analysis system based on optical polarimetry. Unlike previous polarimetric systems which relied on free-space components, our method combines an in-line polarizer, polarization-maintaining fiber, and a polarimeter to measure the arbitrary polarization state of the output, eliminating all free-space elements. Additionally, we develop a more generalized theoretical analysis which allows more information about the polarization state to be obtained via the polarimeter. We experimentally verify our system using a series of elastomer samples made from polydimethylsiloxane (PDMS), a commonly used biomimetic material. By adjusting the base:curing agent ratio of the PDMS, we controllably tune the Young's modulus of the samples to span over an order of magnitude. The measured results are in good agreement with those obtained using a conventional load-frame system. Our fiber-based polarimetric stress sensor shows promise for use as a simple research tool that is portable and suitable for a wide variety of applications.

  17. Design and development of a microwave multifrequency polarimetric scatterometer for biosphere remote sensing

    International Nuclear Information System (INIS)

    Stjernman, A.

    1995-05-01

    The main topic of this research report is the design and development of a multifrequency, polarimetric scatterometer for biosphere remote sensing. The system was developed using a standard HP network analyzer, a crossed log-periodic dipole antenna and a reflector. The scatterometer functions in a linear polarization basis between the L- and X-bands and gathers full-polarimetric information. The standard S-parameter measurements using the network analyzer were related to surface and volume scattering coefficients of rough surface, snow cover and vegetation media. The scatterometer measurements were carried out in the frequency domain to make use of narrow band filters in the receiver chain. The fast Fourier transform was used to convert the frequency domain measurements to the time domain. The range resolution of the system was 20 cm; azimuthal and elevation resolutions are determined by the antenna beam widths. Range side lobes were reduced by making use of appropriate weighting (Kaiser-Bessel window) functions. The accuracy of target characterization depends on the quality of scatterometer calibration. A novel technique to estimate the absolute gain and crosstalk of the radar system was developed. Using a distortion matrix approach, the cross-polarization response of the system was improved by 10 to 25 dB. The radar measurements were validated by comparing point target radar observations with the corresponding theoretical values. Also, measurements of fading decorrelation distance and decorrelation bandwidth or rough surfaces were in good agreement with the theory. Backscatter observations of vegetation and snow cover were comparable to earlier published values for a similar environment. 50 refs, 56 figs, 1 tab

  18. WindSat Space Borne Polarimetric Microwave Radiometer: Data Products and System Performance

    Science.gov (United States)

    Truesdale, D.; Gaiser, P.; Bettenhausen, M. H.; Li, L.; Twarog, E.

    2017-12-01

    WindSat, a satellite-based multi-frequency polarimetric microwave radiometer developed by the Naval Research Laboratory for the U.S. Navy and the NPOESS Integrated Program Office (IPO), has collected over 14 years of fully-polarimetric microwave measurements from space since its launch in 2003. The primary WindSat mission was to demonstrate the capability to retrieve the ocean surface wind vector from a space-based microwave radiometer. The WindSat data is now being used to produce near-real-time products for the ocean surface wind vector, sea surface temperature (SST) and atmospheric columnar water vapor and cloud liquid water over the ocean at the U.S. Navy's Fleet Numerical Meteorological and Oceanographic Center (FNMOC). Several groups are assimilating WindSat data products into numerical weather models with positive results. In addition to providing environmental products over the ocean, the WindSat data set has been exploited for retrievals over land and ice. In particular, the WindSat channel set is well suited to retrieving soil moisture and land surface temperature. We have also built on heritage algorithms to derive sea ice concentration. This paper will provide highlights of WindSat environmental products. The success of the WindSat mission is directly traceable to the on-orbit sensor calibration. WindSat was designed with a one-year mission requirement and three year goal. Now in WindSat's fifteenth year on orbit, we continue to monitor the instrument performance and the calibration stability. Key system performance and calibration parameters include the receiver gains and NEDTs. These parameters are susceptible to component aging and changes in the payload thermal behavior. We will present trends in NEDT and receiver gains over the life of the mission. In addition to its primary mission, the long life of WindSat enables it to provide many forms of risk reduction and lessons learned for future microwave imagers.

  19. A Combined Use of Decomposition and Texture for Terrain Classification of Fully Polarimetric SAR Images

    Science.gov (United States)

    Rodionova, N. V.

    2007-03-01

    This p aper presents two-stag e unsupervised terrain classification of fully polarimetr ic SA R data using Freeman and Durden decomposition based on three simp le scattering mechanisms: surface, volume and double bounce (first step), and textur al features (uncorrelated uniformity , contr ast, inv erse mo men t and entropy) obtained from grey lev el co-occurrence matr ices (GLCM) (second step). Textural f eatures ar e defined in moving w indow 5x5 pixels w ith N=32 (N - number of grey lev els) . This algorith m preserves th e purity of domin ant polarimetric scattering properties and defines textural features in each scatter ing category. It is shown better object discrimin ation after app lying textur e w ith in fix ed scattering category. Speckle r eduction is one of th e main mo ments in imag e interpr etation improvement because of its great influen ce on textur e. Results from unfiltered and Lee filtered polar imetr ic SAR imag es show that the v alues of contrast and en tropy decr ease and th e values of uniformity and inverse moment increase with speckle reduction, that's tru e for all polarizations (HH, VV, HV). Th e d iscr imination b etw een objects increases after speckle f ilter ing. Polar ization influen ce on textur e features is def ined by calculating th e features in SAR images w ith HH , VV and HV polarizations before and after speck le filter ing, and then creating RG B images. It is shown mor e polarization inf luence on textur e features (uniformity , inverse mo ment and entropy) before filtering and less influen ce - after speck le f iltering. I t's not true for contrast wher e polar ization influen ce is not ch anged practically w ith filtering. SIR-C/X-SA R SLC L-band imag es of Moscow r egion are used for illustr ation.

  20. Design and development of a microwave multifrequency polarimetric scatterometer for biosphere remote sensing

    Energy Technology Data Exchange (ETDEWEB)

    Stjernman, A.

    1995-05-01

    The main topic of this research report is the design and development of a multifrequency, polarimetric scatterometer for biosphere remote sensing. The system was developed using a standard HP network analyzer, a crossed log-periodic dipole antenna and a reflector. The scatterometer functions in a linear polarization basis between the L- and X-bands and gathers full-polarimetric information. The standard S-parameter measurements using the network analyzer were related to surface and volume scattering coefficients of rough surface, snow cover and vegetation media. The scatterometer measurements were carried out in the frequency domain to make use of narrow band filters in the receiver chain. The fast Fourier transform was used to convert the frequency domain measurements to the time domain. The range resolution of the system was 20 cm; azimuthal and elevation resolutions are determined by the antenna beam widths. Range side lobes were reduced by making use of appropriate weighting (Kaiser-Bessel window) functions. The accuracy of target characterization depends on the quality of scatterometer calibration. A novel technique to estimate the absolute gain and crosstalk of the radar system was developed. Using a distortion matrix approach, the cross-polarization response of the system was improved by 10 to 25 dB. The radar measurements were validated by comparing point target radar observations with the corresponding theoretical values. Also, measurements of fading decorrelation distance and decorrelation bandwidth or rough surfaces were in good agreement with the theory. Backscatter observations of vegetation and snow cover were comparable to earlier published values for a similar environment. 50 refs, 56 figs, 1 tab.

  1. Image Enhancement and Speckle Reduction of Full Polarimetric SAR Data by Gaussian Markov Random Field

    Science.gov (United States)

    Mahdian, M.; Motagh, M.; Akbari, V.

    2013-09-01

    In recent years, the use of Polarimetric Synthetic Aperture Radar (PolSAR) data in different applications dramatically has been increased. In SAR imagery an interference phenomenon with random behavior exists which is called speckle noise. The interpretation of data encounters some troubles due to the presence of speckle which can be considered as a multiplicative noise affecting all coherent imaging systems. Indeed, speckle degrade radiometric resolution of PolSAR images, therefore it is needful to perform speckle filtering on the SAR data type. Markov Random Field (MRF) has proven to be a powerful method for drawing out eliciting contextual information from remotely sensed images. In the present paper, a probability density function (PDF), which is fitted well with the PolSAR data based on the goodness-of-fit test, is first obtained for the pixel-wise analysis. Then the contextual smoothing is achieved with the MRF method. This novel speckle reduction method combines an advanced statistical distribution with spatial contextual information for PolSAR data. These two parts of information are combined based on weighted summation of pixel-wise and contextual models. This approach not only preserves edge information in the images, but also improves signal-to-noise ratio of the results. The method maintains the mean value of original signal in the homogenous areas and preserves the edges of features in the heterogeneous regions. Experiments on real medium resolution ALOS data from Tehran, and also high resolution full polarimetric SAR data over the Oberpfaffenhofen test-site in Germany, demonstrate the effectiveness of the algorithm compared with well-known despeckling methods.

  2. Retrieval of Macro- and Micro-Physical Properties of Oceanic Hydrosols from Polarimetric Observations

    Science.gov (United States)

    Ibrahim, Amir; Gilerson, Alexander; Chowdhary, Jacek; Ahmed, Samir

    2016-01-01

    Remote sensing has mainly relied on measurements of scalar radiance and its spectral and angular features to retrieve micro- and macro-physical properties of aerosols/hydrosols. However, it is recognized that measurements that include the polarimetric characteristics of light provide more intrinsic information about particulate scattering. To take advantage of this, we used vector radiative transfer (VRT) simulations and developed an analytical relationship to retrieve the macro and micro-physical properties of the oceanic hydrosols. Specifically, we investigated the relationship between the observed degree of linear polarization (DoLP) and the ratio of attenuation-to- absorption coefficients (c/a) in water, from which the scattering coefficient can be readily computed (b equals c minus a), after retrieving a. This relationship was parameterized for various scattering geometries, including sensor zenith/azimuth angles relative to the Sun's principal plane, and for varying Sun zenith angles. An inversion method was also developed for the retrieval of the microphysical properties of hydrosols, such as the bulk refractive index and the particle size distribution. The DoLP vs c/a relationship was tested and validated against in-situ measurements of underwater light polarization obtained by a custom-built polarimeter and measurements of the coefficients a and c, obtained using an in-water WET (Western Environmental Technologies) Labs ac-s (attenuation coefficients In-Situ Spectrophotometer) instrument package. These measurements confirmed the validity of the approach, with retrievals of attenuation coefficients showing a high coefficient of determination depending on the wavelength. We also performed a sensitivity analysis of the DoLP at the Top of Atmosphere (TOA) over coastal waters showing the possibility of polarimetric remote sensing application for ocean color.

  3. QUEST1 VARIABILITY SURVEY. III. LIGHT CURVE CATALOG UPDATE

    International Nuclear Information System (INIS)

    Rengstorf, A. W.; Thompson, D. L.; Mufson, S. L.; Honeycutt, R. K.; Adams, B.; Baltay, C.; Gebhard, M.; Andrews, P.; Coppi, P.; Emmet, W.; Vivas, A. K.; Abad, C.; Bongiovanni, A.; Briceno, C.; Bruzual, G.; Prugna, F. Della; Hernandez, J.; Bailyn, C.; Ferrin, I.; Fuenmayor, F.

    2009-01-01

    This paper reports an update to the QUEST1 (QUasar Equatorial Survey Team, Phase 1) Variability Survey (QVS) light curve catalog, which links QVS instrumental magnitude light curves to Sloan Digital Sky Survey (SDSS) objects and photometry. In the time since the original QVS catalog release, the overlap between publicly available SDSS data and QVS data has increased by 8% in sky coverage and 16,728 in number of matched objects. The astrometric matching and the treatment of SDSS masks have been refined for the updated catalog. We report on these improvements and present multiple bandpass light curves, global variability information, and matched SDSS photometry for 214,941 QUEST1 objects.

  4. Elliptic Curves and Number Theory

    Indian Academy of Sciences (India)

    R. Sujatha, School of Mathematics, Tata Institute of Fundamental Research, Mumbai, INDIA

    1. Aim: To explain the connection between a simple ancient problem in number theory and a deep sophisticated conjecture about Elliptic Curves. ('arithmetic Geometry'). Notation: N : set of natural numbers (1,2,3,...) ...

  5. 51Cr - erythrocyte survival curves

    International Nuclear Information System (INIS)

    Paiva Costa, J. de.

    1982-07-01

    Sixteen patients were studied, being fifteen patients in hemolytic state, and a normal individual as a witness. The aim was to obtain better techniques for the analysis of the erythrocytes, survival curves, according to the recommendations of the International Committee of Hematology. It was used the radiochromatic method as a tracer. Previously a revisional study of the International Literature was made in its aspects inherent to the work in execution, rendering possible to establish comparisons and clarify phonomena observed in cur investigation. Several parameters were considered in this study, hindering both the exponential and the linear curves. The analysis of the survival curves of the erythrocytes in the studied group, revealed that the elution factor did not present a homogeneous answer quantitatively to all, though, the result of the analysis of these curves have been established, through listed programs in the electronic calculator. (Author) [pt

  6. Management of the learning curve

    DEFF Research Database (Denmark)

    Pedersen, Peter-Christian; Slepniov, Dmitrij

    2016-01-01

    Purpose – This paper focuses on the management of the learning curve in overseas capacity expansions. The purpose of this paper is to unravel the direct as well as indirect influences on the learning curve and to advance the understanding of how these affect its management. Design/methodology...... the dimensions of the learning process involved in a capacity expansion project and identified the direct and indirect labour influences on the production learning curve. On this basis, the study proposes solutions to managing learning curves in overseas capacity expansions. Furthermore, the paper concludes...... employs qualitative methodology and draws on a longitudinal, factory-level analysis of an in-depth case study of a Danish wind turbine manufacturer. Findings – This study goes beyond a simplistic treatment of the lead time and learning required to establish a new capacity. The authors examined...

  7. Nonlinear mechanics of rigidifying curves.

    Science.gov (United States)

    Al Mosleh, Salem; Santangelo, Christian

    2017-07-01

    Thin shells are characterized by a high cost of stretching compared to bending. As a result isometries of the midsurface of a shell play a crucial role in their mechanics. In turn, curves on the midsurface with zero normal curvature play a critical role in determining the number and behavior of isometries. In this paper, we show how the presence of these curves results in a decrease in the number of linear isometries. Paradoxically, shells are also known to continuously fold more easily across these rigidifying curves than other curves on the surface. We show how including nonlinearities in the strain can explain these phenomena and demonstrate folding isometries with explicit solutions to the nonlinear isometry equations. In addition to explicit solutions, exact geometric arguments are given to validate and guide our analysis in a coordinate-free way.

  8. Early vertical correction of the deep curve of Spee.

    Science.gov (United States)

    Martins, Renato Parsekian

    2017-01-01

    Even though few technological advancements have occurred in Orthodontics recently, the search for more efficient treatments continues. This paper analyses how to accelerate and improve one of the most arduous phases of orthodontic treatment, i.e., correction of the curve of Spee. The leveling of a deep curve of Spee can happen simultaneously with the alignment phase through a method called Early Vertical Correction (EVC). This technique uses two cantilevers affixed to the initial flexible archwire. This paper describes the force system produced by EVC and how to control its side effects. The EVC can reduce treatment time in malocclusions with deep curves of Spee, by combining two phases of the therapy, which clinicians ordinarily pursue sequentially.

  9. Early vertical correction of the deep curve of Spee

    Directory of Open Access Journals (Sweden)

    Renato Parsekian Martins

    Full Text Available ABSTRACT Even though few technological advancements have occurred in Orthodontics recently, the search for more efficient treatments continues. This paper analyses how to accelerate and improve one of the most arduous phases of orthodontic treatment, i.e., correction of the curve of Spee. The leveling of a deep curve of Spee can happen simultaneously with the alignment phase through a method called Early Vertical Correction (EVC. This technique uses two cantilevers affixed to the initial flexible archwire. This paper describes the force system produced by EVC and how to control its side effects. The EVC can reduce treatment time in malocclusions with deep curves of Spee, by combining two phases of the therapy, which clinicians ordinarily pursue sequentially.

  10. Dissolution glow curve in LLD

    International Nuclear Information System (INIS)

    Haverkamp, U.; Wiezorek, C.; Poetter, R.

    1990-01-01

    Lyoluminescence dosimetry is based upon light emission during dissolution of previously irradiated dosimetric materials. The lyoluminescence signal is expressed in the dissolution glow curve. These curves begin, depending on the dissolution system, with a high peak followed by an exponentially decreasing intensity. System parameters that influence the graph of the dissolution glow curve, are, for example, injection speed, temperature and pH value of the solution and the design of the dissolution cell. The initial peak does not significantly correlate with the absorbed dose, it is mainly an effect of the injection. The decay of the curve consists of two exponential components: one fast and one slow. The components depend on the absorbed dose and the dosimetric materials used. In particular, the slow component correlates with the absorbed dose. In contrast to the fast component the argument of the exponential function of the slow component is independent of the dosimetric materials investigated: trehalose, glucose and mannitol. The maximum value, following the peak of the curve, and the integral light output are a measure of the absorbed dose. The reason for the different light outputs of various dosimetric materials after irradiation with the same dose is the differing solubility. The character of the dissolution glow curves is the same following irradiation with photons, electrons or neutrons. (author)

  11. Aerosol Retrieval Sensitivity and Error Analysis for the Cloud and Aerosol Polarimetric Imager on Board TanSat: The Effect of Multi-Angle Measurement

    Directory of Open Access Journals (Sweden)

    Xi Chen

    2017-02-01

    Full Text Available Aerosol scattering is an important source of error in CO2 retrievals from satellite. This paper presents an analysis of aerosol information content from the Cloud and Aerosol Polarimetric Imager (CAPI onboard the Chinese Carbon Dioxide Observation Satellite (TanSat to be launched in 2016. Based on optimal estimation theory, aerosol information content is quantified from radiance and polarization observed by CAPI in terms of the degrees of freedom for the signal (DFS. A linearized vector radiative transfer model is used with a linearized Mie code to simulate observation and sensitivity (or Jacobians with respect to aerosol parameters. In satellite nadir mode, the DFS for aerosol optical depth is the largest, but for mode radius, it is only 0.55. Observation geometry is found to affect aerosol DFS based on the aerosol scattering phase function from the comparison between different viewing zenith angles or solar zenith angles. When TanSat is operated in target mode, we note that multi-angle retrieval represented by three along-track measurements provides additional 0.31 DFS on average, mainly from mode radius. When adding another two measurements, the a posteriori error decreases by another 2%–6%. The correlation coefficients between retrieved parameters show that aerosol is strongly correlated with surface reflectance, but multi-angle retrieval can weaken this correlation.

  12. Considerations for reference pump curves

    International Nuclear Information System (INIS)

    Stockton, N.B.

    1992-01-01

    This paper examines problems associated with inservice testing (IST) of pumps to assess their hydraulic performance using reference pump curves to establish acceptance criteria. Safety-related pumps at nuclear power plants are tested under the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (the Code), Section 11. The Code requires testing pumps at specific reference points of differential pressure or flow rate that can be readily duplicated during subsequent tests. There are many cases where test conditions cannot be duplicated. For some pumps, such as service water or component cooling pumps, the flow rate at any time depends on plant conditions and the arrangement of multiple independent and constantly changing loads. System conditions cannot be controlled to duplicate a specific reference value. In these cases, utilities frequently request to use pump curves for comparison of test data for acceptance. There is no prescribed method for developing a pump reference curve. The methods vary and may yield substantially different results. Some results are conservative when compared to the Code requirements; some are not. The errors associated with different curve testing techniques should be understood and controlled within reasonable bounds. Manufacturer's pump curves, in general, are not sufficiently accurate to use as reference pump curves for IST. Testing using reference curves generated with polynomial least squares fits over limited ranges of pump operation, cubic spline interpolation, or cubic spline least squares fits can provide a measure of pump hydraulic performance that is at least as accurate as the Code required method. Regardless of the test method, error can be reduced by using more accurate instruments, by correcting for systematic errors, by increasing the number of data points, and by taking repetitive measurements at each data point

  13. Curve Digitizer – A software for multiple curves digitizing

    Directory of Open Access Journals (Sweden)

    Florentin ŞPERLEA

    2010-06-01

    Full Text Available The Curve Digitizer is software that extracts data from an image file representing a graphicand returns them as pairs of numbers which can then be used for further analysis and applications.Numbers can be read on a computer screen stored in files or copied on paper. The final result is adata set that can be used with other tools such as MSEXCEL. Curve Digitizer provides a useful toolfor any researcher or engineer interested in quantifying the data displayed graphically. The image filecan be obtained by scanning a document

  14. COMPARISON BETWEEN SPECTRAL, SPATIAL AND POLARIMETRIC CLASSIFICATION OF URBAN AND PERIURBAN LANDCOVER USING TEMPORAL SENTINEL – 1 IMAGES

    Directory of Open Access Journals (Sweden)

    K. Roychowdhury

    2016-06-01

    Full Text Available Landcover is the easiest detectable indicator of human interventions on land. Urban and peri-urban areas present a complex combination of landcover, which makes classification challenging. This paper assesses the different methods of classifying landcover using dual polarimetric Sentinel-1 data collected during monsoon (July and winter (December months of 2015. Four broad landcover classes such as built up areas, water bodies and wetlands, vegetation and open spaces of Kolkata and its surrounding regions were identified. Polarimetric analyses were conducted on Single Look Complex (SLC data of the region while ground range detected (GRD data were used for spectral and spatial classification. Unsupervised classification by means of K-Means clustering used backscatter values and was able to identify homogenous landcovers over the study area. The results produced an overall accuracy of less than 50% for both the seasons. Higher classification accuracy (around 70% was achieved by adding texture variables as inputs along with the backscatter values. However, the accuracy of classification increased significantly with polarimetric analyses. The overall accuracy was around 80% in Wishart H-A-Alpha unsupervised classification. The method was useful in identifying urban areas due to their double-bounce scattering and vegetated areas, which have more random scattering. Normalized Difference Built-up index (NDBI and Normalized Difference Vegetation Index (NDVI obtained from Landsat 8 data over the study area were used to verify vegetation and urban classes. The study compares the accuracies of different methods of classifying landcover using medium resolution SAR data in a complex urban area and suggests that polarimetric analyses present the most accurate results for urban and suburban areas.

  15. Precipitation microphysics characteristics of a Typhoon Matmo (2014) rainband after landfall over eastern China based on polarimetric radar observations

    Science.gov (United States)

    Wang, Mingjun; Zhao, Kun; Xue, Ming; Zhang, Guifu; Liu, Su; Wen, Long; Chen, Gang

    2016-10-01

    The evolution of microphysical characteristics of a rainband in Typhoon Matmo (2014) over eastern China, through its onset, developing, mature, and dissipating stages, is documented using observations from an S band polarimetric Doppler radar and a two-dimensional video disdrometer (2DVD). The drop size distributions observed by the 2DVD and retrieved from the polarimetric radar measurements indicate that the convection in the rainband generally contains smaller drops and higher number concentrations than the typical maritime type convection described in Bringi et al. (2003). The average mass-weighted mean diameter (Dm) of convective precipitation in the rainband is about 1.41 mm, and the average logarithmic normalized intercept (Nw) is 4.67 log10 mm-1 m-3. To further investigate the dominant microphysical processes, the evolution of the vertical structures of polarimetric variables is examined. Results show that complex ice processes are involved above the freezing level, while it is most likely that the accretion and/or coalescence processes dominate below the freezing level throughout the rainband life cycle. A combined examination of the polarimetric measurements and profiles of estimated vertical liquid and ice water contents indicates that the conversion of cloud water into rainwater through cloud water accretion by raindrops plays a dominant role in producing heavy rainfall. The high estimated precipitation efficiency of 50% also suggests that cloud water accretion is the dominant mechanism for producing heavy rainfall. This study represents the first time that radar and 2DVD observations are used together to characterize the microphysical characteristics and precipitation efficiency for typhoon rainbands in China.

  16. Evaluation of Digital Classification of Polarimetric SAR Data for Iron-Mineralized Laterites Mapping in the Amazon Region

    Directory of Open Access Journals (Sweden)

    Cleber G. Oliveira

    2013-06-01

    Full Text Available This study evaluates the potential of C- and L-band polarimetric SAR data for the discrimination of iron-mineralized laterites in the Brazilian Amazon region. The study area is the N1 plateau located on the northern border of the Carajás Mineral Province, the most important Brazilian mineral province which has numerous mineral deposits, particularly the world’s largest iron deposits. The plateau is covered by low-density savanna-type vegetation (campus rupestres which contrasts visibly with the dense equatorial forest. The laterites are subdivided into three units: chemical crust, iron-ore duricrust, and hematite, of which only the latter two are of economic interest. Full polarimetric data from the airborne R99B sensor of the SIVAM/CENSIPAM (L-band system and the RADARSAT-2 satellite (C-band were evaluated. The study focused on an assessment of distinct schemes for digital classification based on decomposition theory and hybrid approach, which incorporates statistical analysis as input data derived from the target decomposition modeling. The results indicated that the polarimetric classifications presented a poor performance, with global Kappa values below 0.20. The accuracy for the identification of units of economic interest varied from 55% to 89%, albeit with high commission error values. In addition, the results using L-band were considered superior compared to C-band, which suggest that the roughness scale for laterite discrimination in the area is nearer to L than to C-band.

  17. EFFECT OF POLARIMETRIC NOISE ON THE ESTIMATION OF TWIST AND MAGNETIC ENERGY OF FORCE-FREE FIELDS

    International Nuclear Information System (INIS)

    Tiwari, Sanjiv Kumar; Venkatakrishnan, P.; Gosain, Sanjay; Joshi, Jayant

    2009-01-01

    The force-free parameter α, also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global value of α for a whole active region gives the degree of twist per unit axial length. We investigate the effect of polarimetric noise on the calculation of global α value and magnetic energy of an analytical bipole. The analytical bipole has been generated using the force-free field approximation with a known value of constant α and magnetic energy. The magnetic parameters obtained from the analytical bipole are used to generate Stokes profiles from the Unno-Rachkovsky solutions for polarized radiative transfer equations. Then we add random noise of the order of 10 -3 of the continuum intensity (I c ) in these profiles to simulate the real profiles obtained by modern spectropolarimeters such as Hinode (SOT/SP), SVM (USO), ASP, DLSP, POLIS, and SOLIS etc. These noisy profiles are then inverted using a Milne-Eddington inversion code to retrieve the magnetic parameters. Hundred realizations of this process of adding random noise and polarimetric inversion is repeated to study the distribution of error in global α and magnetic energy values. The results show that (1) the sign of α is not influenced by polarimetric noise and very accurate values of global twist can be calculated, and (2) accurate estimation of magnetic energy with uncertainty as low as 0.5% is possible under the force-free condition.

  18. Automated chromatographic system with polarimetric detection laser applied in the control of fermentation processes and seaweed extracts characterization

    International Nuclear Information System (INIS)

    Fajer, V.; Naranjo, S.; Mora, W.; Patinno, R.; Coba, E.; Michelena, G.

    2012-01-01

    There are presented applications and innovations of chromatographic and polarimetric systems in which develop methodologies for measuring the input molasses and the resulting product of a fermentation process of alcohol from a rich honey and evaluation of the fermentation process honey servery in obtaining a drink native to the Yucatan region. Composition was assessed optically active substances in seaweed, of interest to the pharmaceutical industry. The findings provide measurements alternative raw materials and products of the sugar industry, beekeeping and pharmaceutical liquid chromatography with automated polarimetric detection reduces measurement times up to 15 min, making it comparable to the times of high chromatography resolution, significantly reducing operating costs. By chromatography system with polarimetric detection (SCDP) is new columns have included standard size designed by the authors, which allow process samples with volumes up to 1 ml and reduce measurement time to 15 min, decreasing to 5 times the volume sample and halving the time of measurement. Was evaluated determining the concentration of substances using the peaks of the chromatograms obtained for the different columns and calculate the uncertainty of measurements. The results relating to the improvement of a data acquisition program (ADQUIPOL v.2.0) and new programs for the preparation of chromatograms (CROMAPOL CROMAPOL V.1.0 and V.1.2) provide important benefits, which allow a considerable saving of time the processing of the results and can be applied in other chromatography systems with the appropriate adjustments. (Author)

  19. A NEW SAR CLASSIFICATION SCHEME FOR SEDIMENTS ON INTERTIDAL FLATS BASED ON MULTI-FREQUENCY POLARIMETRIC SAR IMAGERY

    Directory of Open Access Journals (Sweden)

    W. Wang

    2017-11-01

    Full Text Available We present a new classification scheme for muddy and sandy sediments on exposed intertidal flats, which is based on synthetic aperture radar (SAR data, and use ALOS-2 (L-band, Radarsat-2 (C-band and TerraSAR-X (X-band fully polarimetric SAR imagery to demonstrate its effectiveness. Four test sites on the German North Sea coast were chosen, which represent typical surface compositions of different sediments, vegetation, and habitats, and of which a large amount of SAR is used for our analyses. Both Freeman-Durden and Cloude-Pottier polarimetric decomposition are utilized, and an additional descriptor called Double-Bounce Eigenvalue Relative Difference (DERD is introduced into the feature sets instead of the original polarimetric intensity channels. The classification is conducted following Random Forest theory, and the results are verified using ground truth data from field campaigns and an existing classification based on optical imagery. In addition, the use of Kennaugh elements for classification purposes is demonstrated using both fully and dual-polarization multi-frequency and multi-temporal SAR data. Our results show that the proposed classification scheme can be applied for the discrimination of muddy and sandy sediments using L-, C-, and X-band SAR images, while SAR imagery acquired at short wavelengths (C- and X-band can also be used to detect more detailed features such as bivalve beds on intertidal flats.

  20. Geomorphological mapping of ice-free areas using polarimetric RADARSAT-2 data on Fildes Peninsula and Ardley Island, Antarctica

    Science.gov (United States)

    Schmid, T.; López-Martínez, J.; Guillaso, S.; Serrano, E.; D'Hondt, O.; Koch, M.; Nieto, A.; O'Neill, T.; Mink, S.; Durán, J. J.; Maestro, A.

    2017-09-01

    Satellite-borne Synthetic Aperture Radar (SAR) has been used for characterizing and mapping in two relevant ice-free areas in the South Shetland Islands. The objective has been to identify and characterize land surface covers that mainly include periglacial and glacial landforms, using fully polarimetric SAR C band RADARSAT-2 data, on Fildes Peninsula that forms part of King George Island, and Ardley Island. Polarimetric parameters obtained from the SAR data, a selection of field based training and validation sites and a supervised classification approach, using the support vector machine were chosen to determine the spatial distribution of the different landforms. Eight periglacial and glacial landforms were characterized according to their scattering mechanisms using a set of 48 polarimetric parameters. The mapping of the most representative surface covers included colluvial deposits, stone fields and pavements, patterned ground, glacial till and rock outcrops, lakes and glacier ice. The overall accuracy of the results was estimated at 81%, a significant value when mapping areas that are within isolated regions where access is limited. Periglacial surface covers such as stone fields and pavements occupy 25% and patterned ground over 20% of the ice-free areas. These are results that form the basis for an extensive monitoring of the ice-free areas throughout the northern Antarctic Peninsula region.

  1. Calibration curves for biological dosimetry

    International Nuclear Information System (INIS)

    Guerrero C, C.; Brena V, M. . E-mail cgc@nuclear.inin.mx

    2004-01-01

    The generated information by the investigations in different laboratories of the world, included the ININ, in which settles down that certain class of chromosomal leisure it increases in function of the dose and radiation type, has given by result the obtaining of calibrated curves that are applied in the well-known technique as biological dosimetry. In this work is presented a summary of the work made in the laboratory that includes the calibrated curves for gamma radiation of 60 Cobalt and X rays of 250 k Vp, examples of presumed exposure to ionizing radiation, resolved by means of aberration analysis and the corresponding dose estimate through the equations of the respective curves and finally a comparison among the dose calculations in those people affected by the accident of Ciudad Juarez, carried out by the group of Oak Ridge, USA and those obtained in this laboratory. (Author)

  2. Laffer Curves and Home Production

    Directory of Open Access Journals (Sweden)

    Kotamäki Mauri

    2017-06-01

    Full Text Available In the earlier related literature, consumption tax rate Laffer curve is found to be strictly increasing (see Trabandt and Uhlig (2011. In this paper, a general equilibrium macro model is augmented by introducing a substitute for private consumption in the form of home production. The introduction of home production brings about an additional margin of adjustment – an increase in consumption tax rate not only decreases labor supply and reduces the consumption tax base but also allows a substitution of market goods with home-produced goods. The main objective of this paper is to show that, after the introduction of home production, the consumption tax Laffer curve exhibits an inverse U-shape. Also the income tax Laffer curves are significantly altered. The result shown in this paper casts doubt on some of the earlier results in the literature.

  3. Rational points on elliptic curves

    CERN Document Server

    Silverman, Joseph H

    2015-01-01

    The theory of elliptic curves involves a pleasing blend of algebra, geometry, analysis, and number theory. This book stresses this interplay as it develops the basic theory, thereby providing an opportunity for advanced undergraduates to appreciate the unity of modern mathematics. At the same time, every effort has been made to use only methods and results commonly included in the undergraduate curriculum. This accessibility, the informal writing style, and a wealth of exercises make Rational Points on Elliptic Curves an ideal introduction for students at all levels who are interested in learning about Diophantine equations and arithmetic geometry. Most concretely, an elliptic curve is the set of zeroes of a cubic polynomial in two variables. If the polynomial has rational coefficients, then one can ask for a description of those zeroes whose coordinates are either integers or rational numbers. It is this number theoretic question that is the main subject of this book. Topics covered include the geometry and ...

  4. The New Keynesian Phillips Curve

    DEFF Research Database (Denmark)

    Ólafsson, Tjörvi

    This paper provides a survey on the recent literature on the new Keynesian Phillips curve: the controversies surrounding its microfoundation and estimation, the approaches that have been tried to improve its empirical fit and the challenges it faces adapting to the open-economy framework. The new...... Keynesian Phillips curve has been severely criticized for poor empirical dynamics. Suggested improvements involve making some adjustments to the standard sticky price framework, e.g. introducing backwardness and real rigidities, or abandoning the sticky price model and relying on models of inattentiveness......, learning or state-dependant pricing. The introduction of openeconomy factors into the new Keynesian Phillips curve complicate matters further as it must capture the nexus between price setting, inflation and the exchange rate. This is nevertheless a crucial feature for any model to be used for inflation...

  5. Electro-Mechanical Resonance Curves

    Science.gov (United States)

    Greenslade, Thomas B.

    2018-03-01

    Recently I have been investigating the frequency response of galvanometers. These are direct-current devices used to measure small currents. By using a low-frequency function generator to supply the alternating-current signal and a stopwatch smartphone app to measure the period, I was able to take data to allow a resonance curve to be drawn. This is the sort of project that should provide a fascinating research experience for the introductory physics student. In this article I will discuss the galvanometers that I used in this work, and will show a resonance curve for one of them.

  6. Migration and the Wage Curve:

    DEFF Research Database (Denmark)

    Brücker, Herbert; Jahn, Elke J.

      Based on a wage curve approach we examine the labor market effects of migration in Germany. The wage curve relies on the assumption that wages respond to a change in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously...... with a vocational degree. The wage and employment effects of migration are moderate: a 1 percent increase in the German labor force through immigration increases the aggregate unemployment rate by less than 0.1 percentage points and reduces average wages by less 0.1 percent. While native workers benefit from...... increased wages and lower unemployment, foreign workers are adversely affected....

  7. Shock detachment from curved wedges

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.

  8. The potential of linear discriminative Laplacian eigenmaps dimensionality reduction in polarimetric SAR classification for agricultural areas

    Science.gov (United States)

    Shi, Lei; Zhang, Lefei; Zhao, Lingli; Yang, Jie; Li, PingXiang; Zhang, Liangpei

    2013-12-01

    In this paper, the linear discriminative Laplacian eigenmaps (LDLE) dimensionality reduction (DR) algorithm is introduced to C-band polarimetric synthetic aperture radar (PolSAR) agricultural classification. A collection of homogenous areas of the same crop class usually presents physical parameter variation, such as the biomass and soil moisture. Furthermore, the local incidence angle also impacts a lot on the same crop category when the vegetation layer is penetrable with C-band radar. We name this phenomenon as the "observed variation of the same category" (OVSC). The most common PolSAR features, e.g., the Freeman-Durden and Cloude-Pottier decompositions, show an inadequate performance with OVSC. In our research, more than 40 coherent and incoherent PolSAR decomposition models are stacked into the high-dimensionality feature cube to describe the various physical parameters. The LDLE algorithm is then performed on the observed feature cube, with the aim of simultaneously pushing the local samples of the same category closer to each other, as well as maximizing the distance between local samples of different categories in the learnt subspace. Finally, the classification result is obtained by nearest neighbor (NN) or Wishart classification in the reduced feature space. In the simulation experiment, eight crop blocks are picked to generate a test patch from the 1991 Airborne Synthetic Aperture Radar (AIRSAR) C-band fully polarimetric data from of Flevoland test site. Locality preserving projections (LPP) and principal component analysis (PCA) are then utilized to evaluate the DR results of the proposed method. The classification results show that LDLE can distinguish the influence of the physical parameters and achieve a 99% overall accuracy, which is better than LPP (97%), PCA (88%), NN (89%), and Wishart (88%). In the real data experiment, the Chinese Hailaer nationalized farm RadarSat2 PolSAR test set is used, and the classification accuracy is around 94%, which

  9. Dual Smarandache Curves of a Timelike Curve lying on Unit dual Lorentzian Sphere

    OpenAIRE

    Kahraman, Tanju; Hüseyin Ugurlu, Hasan

    2016-01-01

    In this paper, we give Darboux approximation for dual Smarandache curves of time like curve on unit dual Lorentzian sphere. Firstly, we define the four types of dual Smarandache curves of a timelike curve lying on dual Lorentzian sphere.

  10. Archaeomagnetic SV curve for Belgium

    Science.gov (United States)

    Ech-chakrouni, Souad; Hus, Jozef

    2017-04-01

    Archaeomagnetic secular variation curves have been established for different countries in Europe, especially when different archeological sites are more or less uniformly distributed in time are available. The disadvantage in that case is that data had to be relocated to a single reference site. The proximity of the reference locality Paris to Belgium makes that we used the French archaeomagnetic SV curve for the last three millennia up to the present for archaeomagnetic dating undated baked structures. In total, 85 baked structures have been examined, unearthed in 24 archaeological sites of the territory of Belgium. The ChRM of each sample was obtained by principal component analysis for at least three demagnetisation steps (Kirschvink 1980). Except for some outliers, the ChRM directions are very coherent with a high confidence factor (α95archaeomagnetism. At present, only six baked structures were dated radiometrically and may be considered as reference data for a limited area about 30500 km2 in Western Europe. The ultimate aim is to construct an archaeomagnetic SV curve for Belgium with Uccle as reference locality, where the first measurement of the geomagnetic field was done in 1895. This curve would include all the available reference data in a radius of about 500 km around Uccle. Keywords: secular variation, archaeomagnetic dating, Belgium.

  11. The aeolian dust accumulation curve

    NARCIS (Netherlands)

    Goossens, D.

    2001-01-01

    This article presents a simple physical concept of aeolian dust accumulation, based on the behaviour of the subprocesses of dust deposition and dust erosion. The concept is tested in an aeolian dust wind tunnel. The agreement between the accumulation curve predicted by the model and the accumulation

  12. A Curve for all Reasons

    Indian Academy of Sciences (India)

    The cause-effect relationship for a wide variety of biologi- cal processes from molecular to ecosystem levels can be described by a curvilinear function called the rectangular hyperbola. Although a simple algebraic equation adequately describes this curve, biological models have generated different equations incorporating ...

  13. Survival curves for irradiated cells

    International Nuclear Information System (INIS)

    Gibson, D.K.

    1975-01-01

    The subject of the lecture is the probability of survival of biological cells which have been subjected to ionising radiation. The basic mathematical theories of cell survival as a function of radiation dose are developed. A brief comparison with observed survival curves is made. (author)

  14. Texas curve margin of safety.

    Science.gov (United States)

    2013-01-01

    This software can be used to assist with the assessment of margin of safety for a horizontal curve. It is intended for use by engineers and technicians responsible for safety analysis or management of rural highway pavement or traffic control devices...

  15. Ultrasonic Fetal Cephalometry: Percentiles Curve

    Science.gov (United States)

    Flamme, P.

    1972-01-01

    Measurements by ultrasound of the biparietal diameter of the fetal head during pregnancy are a reliable guide to fetal growth. As a ready means of comparison with the normal we constructed from 4,170 measurements in 1,394 cases a curve showing the percentiles distribution of biparietal diameters for each week of gestation. PMID:5070162

  16. Interpolation and Polynomial Curve Fitting

    Science.gov (United States)

    Yang, Yajun; Gordon, Sheldon P.

    2014-01-01

    Two points determine a line. Three noncollinear points determine a quadratic function. Four points that do not lie on a lower-degree polynomial curve determine a cubic function. In general, n + 1 points uniquely determine a polynomial of degree n, presuming that they do not fall onto a polynomial of lower degree. The process of finding such a…

  17. An appraisal of the learning curve in robotic general surgery.

    Science.gov (United States)

    Pernar, Luise I M; Robertson, Faith C; Tavakkoli, Ali; Sheu, Eric G; Brooks, David C; Smink, Douglas S

    2017-11-01

    Robotic-assisted surgery is used with increasing frequency in general surgery for a variety of applications. In spite of this increase in usage, the learning curve is not yet defined. This study reviews the literature on the learning curve in robotic general surgery to inform adopters of the technology. PubMed and EMBASE searches yielded 3690 abstracts published between July 1986 and March 2016. The abstracts were evaluated based on the following inclusion criteria: written in English, reporting original work, focus on general surgery operations, and with explicit statistical methods. Twenty-six full-length articles were included in final analysis. The articles described the learning curves in colorectal (9 articles, 35%), foregut/bariatric (8, 31%), biliary (5, 19%), and solid organ (4, 15%) surgery. Eighteen of 26 (69%) articles report single-surgeon experiences. Time was used as a measure of the learning curve in all studies (100%); outcomes were examined in 10 (38%). In 12 studies (46%), the authors identified three phases of the learning curve. Numbers of cases needed to achieve plateau performance were wide-ranging but overlapping for different kinds of operations: 19-128 cases for colorectal, 8-95 for foregut/bariatric, 20-48 for biliary, and 10-80 for solid organ surgery. Although robotic surgery is increasingly utilized in general surgery, the literature provides few guidelines on the learning curve for adoption. In this heterogeneous sample of reviewed articles, the number of cases needed to achieve plateau performance varies by case type and the learning curve may have multiple phases as surgeons add more complex cases to their case mix with growing experience. Time is the most common determinant for the learning curve. The literature lacks a uniform assessment of outcomes and complications, which would arguably reflect expertise in a more meaningful way than time to perform the operation alone.

  18. DSD Characteristics of a Mid-Winter Tornadic Storm Using C-Band Polarimetric Radar and Two 2D-Video Disdrometers

    Science.gov (United States)

    Thurai, M.; Petersen, W. A.; Carey, L. A.

    2010-01-01

    Drop size distributions in an evolving tornadic storm are examined using C-band polarimetric radar observations and two 2D-video disdrometers. The E-F2 storm occurred in mid-winter (21 January 2010) in northern Alabama, USA, and caused widespread damage. The evolution of the storm occurred within the C-band radar coverage and moreover, several minutes prior to touch down, the storm passed over a site where several disdrometers including two 2D video disdrometers (2DVD) had been installed. One of the 2DVDs is a low profile unit and the other is a new next generation compact unit currently undergoing performance evaluation. Analyses of the radar data indicate that the main region of precipitation should be treated as a "big-drop" regime case. Even the measured differential reflectivity values (i.e. without attenuation correction) were as high as 6-7 dB within regions of high reflectivity. Standard attenuation-correction methods using differential propagation phase have been "fine tuned" to be applicable to the "big drop" regime. The corrected reflectivity and differential reflectivity data are combined with the co-polar correlation coefficient and specific differential phase to determine the mass-weighted mean diameter, Dm, and the width of the mass spectrum, (sigma)M, as well as the intercept parameter , Nw. Significant areas of high Dm (3-4 mm) were retrieved within the main precipitation areas of the tornadic storm. The "big drop" regime assumption is substantiated by the two sets of 2DVD measurements. The Dm values calculated from 1-minute drop size distributions reached nearly 4 mm, whilst the maximum drop diameters were over 6 mm. The fall velocity measurements from the 2DVD indicate almost all hydrometeors to be fully melted at ground level. Drop shapes for this event are also being investigated from the 2DVD camera data.

  19. Analysis of Dual- and Full-Circular Polarimetric SAR Modes for Rice Phenology Monitoring: An Experimental Investigation through Ground-Based Measurements

    Directory of Open Access Journals (Sweden)

    Yuta Izumi

    2017-04-01

    Full Text Available Circularly polarized synthetic aperture radar (CP-SAR is known to be insensitive to polarization mismatch losses caused by the Faraday rotation effect and antenna misalignment. Additionally, the dual-circular polarimetric (DCP mode has proven to have more polarimetric information than that of the corresponding mode of linear polarization, i.e., the dual-linear polarimetric (DLP mode. Owing to these benefits, this paper investigates the feasibility of CP-SAR for rice monitoring. A ground-based CP-radar system was exploited, and C-band anechoic chamber data of a self-cultivated Japanese rice paddy were acquired from germination to ripening stages. Temporal variations of polarimetric observables derived from full-circular polarimetric (FCP and DCP as well as synthetically generated DLP data are analyzed and assessed with regard to their effectiveness in phenology retrieval. Among different observations, the H / α ¯ plane and triangle plots obtained by three scattering components (surface, double-bounce, and volume scattering for both the FCP and DCP modes are confirmed to have reasonable capability in discriminating the relevant intervals of rice growth.

  20. Improving Wishart Classification of Polarimetric SAR Data Using the Hopfield Neural Network Optimization Approach

    Directory of Open Access Journals (Sweden)

    Íñigo Molina

    2012-11-01

    Full Text Available This paper proposes the optimization relaxation approach based on the analogue Hopfield Neural Network (HNN for cluster refinement of pre-classified Polarimetric Synthetic Aperture Radar (PolSAR image data. We consider the initial classification provided by the maximum-likelihood classifier based on the complex Wishart distribution, which is then supplied to the HNN optimization approach. The goal is to improve the classification results obtained by the Wishart approach. The classification improvement is verified by computing a cluster separability coefficient and a measure of homogeneity within the clusters. During the HNN optimization process, for each iteration and for each pixel, two consistency coefficients are computed, taking into account two types of relations between the pixel under consideration and its corresponding neighbors. Based on these coefficients and on the information coming from the pixel itself, the pixel under study is re-classified. Different experiments are carried out to verify that the proposed approach outperforms other strategies, achieving the best results in terms of separability and a trade-off with the homogeneity preserving relevant structures in the image. The performance is also measured in terms of computational central processing unit (CPU times.